WorldWideScience

Sample records for calibrated heat-pulse method

  1. Calibration of sap flow estimated by the compensation heat pulse method in olive, plum and orange trees: relationships with xylem anatomy.

    Science.gov (United States)

    Fernández, J E; Durán, P J; Palomo, M J; Diaz-Espejo, A; Chamorro, V; Girón, I F

    2006-06-01

    The compensation heat pulse method is widely used to estimate sap flow in conducting organs of woody plants. Being an invasive technique, calibration is crucial to derive correction factors for accurately estimating the sap flow value from the measured heat pulse velocity. We compared the results of excision and perfusion calibration experiments made with mature olive (Olea europaea L. 'Manzanilla de Sevilla'), plum (Prunus domestica L. 'Songal') and orange (Citrus sinensis (L.) Osbeck. 'Cadenero') trees. The calibration experiments were designed according to current knowledge on the application of the technique and the analysis of measured heat pulse velocities. Data on xylem characteristics were obtained from the experimental trees and related to the results of the calibration experiments. The most accurate sap flow values were obtained by assuming a wound width of 2.0 mm for olive and 2.4 mm for plum and orange. Although the three possible methods of integrating the sap velocity profiles produced similar results for all three species, the best results were obtained by calculating sap flow as the weighted sum of the product of sap velocity and the associated sapwood area across the four sensors of the heat-pulse-velocity probes. Anatomical observations showed that the xylem of the studied species can be considered thermally homogeneous. Vessel lumen diameter in orange trees was about twice that in the olive and plum, but vessel density was less than half. Total vessel lumen area per transverse section of xylem tissue was greater in plum than in the other species. These and other anatomical and hydraulic differences may account for the different calibration results obtained for each species. PMID:16510387

  2. Thermal diffusivity measurements of selected fiber reinforced polymer composites using heat pulse method

    OpenAIRE

    G. Wróbel a, S. Pawlak a, *, G. Muzia

    2011-01-01

    Purpose: The objective of this paper was to examine the effect of fiber content on the thermal diffusivity in selected fiber reinforced polymer composites. The influence of fiber type on the thermal diffusivity was also considered and discussed.Design/methodology/approach: The experiments have been performed using a heat pulse method for the thermal diffusivity measurements of engineering materials. For the purpose of the present study, two different types of composite materials with glass or...

  3. [Application of three heat pulse technique-based methods to determine the stem sap flow].

    Science.gov (United States)

    Wang, Sheng; Fan, Jun

    2015-08-01

    It is of critical importance to acquire tree transpiration characters through sap flow methodology to understand tree water physiology, forest ecology and ecosystem water exchange. Tri-probe heat pulse sensors, which are widely utilized in soil thermal parameters and soil evaporation measurement, were applied to implement Salix matsudana sap flow density (Vs) measurements via heat-ratio method (HRM), T-Max method (T-Max) and single-probe heat pulse probe (SHPP) method, and comparative analysis was conducted with additional Grainer's thermal diffusion probes (TDP) measured results. The results showed that, it took about five weeks to reach a stable measurement stage after TPHP installation, Vs measured with three methods in the early stage after installation was 135%-220% higher than Vs in the stable measurement stage, and Vs estimated via HRM, T-Max and SHPP methods were significantly linearly correlated with Vs estimated via TDP method, with R2 of 0.93, 0.73 and 0.91, respectively, and R2 for Vs measured by SHPP and HRM reached 0.94. HRM had relatively higher precision in measuring low rates and reverse sap flow. SHPP method seemed to be very promising to measure sap flow for configuration simplicity and high measuring accuracy, whereas it couldn' t distinguish directions of flow. T-Max method had relatively higher error in sap flow measurement, and it couldn' t measure sap flow below 5 cm3 · cm(-2) · h(-1), thus this method could not be used alone, however it could measure thermal diffusivity for calculating sap flow when other methods were imposed. It was recommended to choose a proper method or a combination of several methods to measure stem sap flow, based on specific research purpose.

  4. Fourier-Analysis of Sawtooth Heat Pulse-Propagation and Comparison with Other Methods Using Jet Data

    NARCIS (Netherlands)

    Mantica, P.; De Luca, F.; Gorini, G.; Jacchia, A.; Hogeweij, G. M. D.; Cardozo, N. J. L.; Kramer, G. J.; Sips, A.C.C.

    1992-01-01

    A new method for the analysis of sawtooth heat pulse propagation is presented. The method is based on Fourier analysis of data where the statistical noise is reduced by a suitable noise reduction procedure. Besides the value of the incremental heat diffusivity (chi(inc)), information on the magnitud

  5. Determining the water use of rambutan and longkong during phenological development by heat-pulse method

    Directory of Open Access Journals (Sweden)

    Sdoodee, S.

    2003-01-01

    Full Text Available The water use of two species of tropical fruit trees: rambutan (Nephelium lappaceum and longkong (Aglaia dookkoo Griff. were investigated by heat-pulse method. The sapflow rate of both species were determined during phenological development. An experiment was established at Prince of Songkla University, Songkhla Province. Characteristics of sapwood in each species and optimum depth for probe implanting on the trunk were investigated. During the measurement period, diurnal changes of photon flux density, leaf water potential and stomatal conductance were recorded. It was found that sapwood of rambutan and longkong were homogeneous. An appropriate probe depth to implant on the trunk was 25 mm from bark. It was found that diurnal changes of sapflow rates of each species varied with the changes of radiation, leaf water potential and stomata conductance. The results of measurement showed that water use decreased at pre-flowering stage, and fruit maturity stage. In rambutan, water use increased during vegetative growth stage followed by flowering stage. The marked increase of water use in rambutan was during fruit development. In longkong, water use increased at the flowering stage followed by vegetative growth stage, and the peak of water use was during fruit development.

  6. Thermal diffusivity measurements of selected fiber reinforced polymer composites using heat pulse method

    Directory of Open Access Journals (Sweden)

    G. Wróbel a, S. Pawlak a, *, G. Muzia

    2011-03-01

    Full Text Available Purpose: The objective of this paper was to examine the effect of fiber content on the thermal diffusivity in selected fiber reinforced polymer composites. The influence of fiber type on the thermal diffusivity was also considered and discussed.Design/methodology/approach: The experiments have been performed using a heat pulse method for the thermal diffusivity measurements of engineering materials. For the purpose of the present study, two different types of composite materials with glass or aramid fiber and with different fiber content were prepared.Findings: For the GFRP composites, the obtained results indicate that the higher is glass fiber content the higher is the thermal diffusivity value. These results shows a linear relationship between fiber content and thermal diffusivity. In the case of KFRP composites, the thermal diffusivity decreases marginally with an increase of fiber content.Research limitations/implications: Due to the relatively high thickness of investigated specimens, in comparison with standard specimens for thermal diffusivity measurements, the obtained values of thermal diffusivity are affected by several factors, e.g. heat losses or temperature-dependent thermo-physical properties. This indicates that the real quantity determined in the present study, was, so-called, apparent thermal diffusivity.Practical implications: The method applied in this work allows to obtain quantitative results, which would be satisfactory to industrial or laboratory applications in the field of non-destructive testing of composite materials.Originality/value: The method initially proposed by Parker et al. in 1961 for the thermal diffusivity measurements of homogeneous solids was successfully applied to determine the thermal diffusivity of non-homogeneous glass and aramid fiber reinforced polymer composites

  7. Using the compensated heat pulse method to monitor trends in stem water content in standing trees.

    Science.gov (United States)

    López-Bernal, Álvaro; Testi, Luca; Villalobos, Francisco J

    2012-11-01

    Studying the dynamics of stem water content (θ) in living trees has an outstanding physiological interest but all the available techniques to measure θ exhibit major drawbacks. In this work, we present a new methodology to estimate variations in θ along with sap velocity using the compensated heat pulse (CHP) technique. One lab experiment was performed on several wooden blocks obtained from three different tree species. Samples were slowly dried and their moisture loss was monitored by both gravimetric approaches and time-domain reflectometry (TDR) or CHP probes in order to contrast the validity of our methodology (volumetric specific heat (VSH)-CHP) over a range of water contents. In addition, a field experiment was conducted to monitor θ fluctuations in standing olive trees (Olea europaea L. cv. 'Arbequina') growing under three different irrigation regimes. In the lab test, the actual θ values deduced gravimetrically differed from the estimates yielded by the VSH-CHP method. However, it could successfully track relative changes in the water stored for the range of θ expected in living wood. Furthermore, the field experiment showed a seasonal change in θ, which was similar in shape and magnitude to those reported in the literature for olive and other Mediterranean tree species. On the other hand, differences in the seasonal patterns of θ between irrigation treatments strongly corresponded with those of sap flow and some leaf water potential measurements. The results of this work suggest that the CHP technique could be employed to monitor the dynamics of both θ and sap flow simultaneously in standing trees and evidence that seasonal changes in θ might be used as a long-term water status indicator. PMID:23095949

  8. Applying the Active Heating Pulse DFOT Method to Drip Irrigation. Characterization of a wetting bulb in drip emitter

    Science.gov (United States)

    Benitez-Buelga, J.; Rodriguez-Sinobas, L.; María Gil-Rodríguez, M.; Sayde, C.; Selker, J. S.

    2011-12-01

    The use of Distributed Fiber Optic Temperature Measurement (DFOT) method for estimating temperature variation along a cable of fiber optic has been largely reported in multiple environmental applications. Recently , its usage has been combined with an active heating pulses technique- measurement of the temperature increase when a certain amount of tension is applied to the stainless jacket surrounding the fiber optic cable-in order to estimate soil water content in field and laboratory conditions with great accuracy . Thus, a methodology potentially capable of monitoring spatial variability and accurately estimates soil water content is created. This study presents a direct application of the Active Heated DFOT method for measuring soil water distribution and wetting bulb of a single drip emitter. In order to do so, three concentric helixes of fiber optics were placed in a hexagonal column of Plexiglas of 0.5 m base radius and 0.6 m height. After being filled up with air-dried loamy soil of controlled bulk density, a pressure compensating drip emitter of 2 L/h discharge was placed on top of the soil column. For an irrigation time of 5 hours and 40 min, 21 heating pulses of 2 minutes and 20W/m, were applied. In addition, soil samples after each heat pulse were also collected. Results showed the potential of this method for monitoring soil water behavior during irrigation and also its capability to estimate soil water content with accuracy.

  9. Detection of volatile impurities in turbine oils by the heat-pulse testing method

    Science.gov (United States)

    Skripov, P. V.; Demin, V. A.; Shangin, V. V.; Starostin, A. A.

    2016-07-01

    The research is aimed at development and implementation of methods and devices to control critical sections of the oil system of the power equipment that operates in the real time mode. The task was to develop a method for rapid detection of volatile impurities in turbine oils. The approach to the study is based on quantitative assessment of the short-term thermal stability of the substance that is formally associated with the content of the volatile impurity. The approach was selected on the basis of the results of search experiments taking into consideration the formulation of requirements for the method and the device, viz., (1) the method should reliably determine the moisture content in the range of 10-150 g of the impurity per ton of oil and (2) the device is to be applicable "in situ." For this purpose, a variant of the method of the controlled pulse heating of a wire probe, a resistance thermometer, has been developed. The advantages of the method are its speed, sensitivity to small contents of volatile impurities regardless of the nature of the impurity, and smallness of methodologically contributed perturbation. The heating conditions of the probe most sensitive to the appearance of moisture— including its trace amounts—in the system, has been defined. The duration of the measurement is on the order of milliseconds; the heat flux density through the surface of the probe reaches 1 MW/m2. The essence of the method consists in measuring, in the characteristic time interval, the temperature of the thermal instability onset associated with the content of the volatile impurity. The approach proposed by the authors is aimed at increasing the lifetime of the oil and preventing unpredictable failures of the operating equipment.

  10. Application of active heat pulse method with fiber optic temperature sensing for estimation of wetting bulbs and water distribution in drip emitters.

    OpenAIRE

    Gil Rodríguez, María; Rodríguez Sinobas, Leonor; Benitez Buelga, Javier; Sánchez Calvo, Raúl

    2013-01-01

    Through the use of the Distributed Fiber Optic Temperature Measurement (DFOT) method, it is possible to measure the temperature in small intervals (on the order of centimeters) for long distances (on the order of kilometers) with a high temporal frequency and great accuracy. The heat pulse method consists of applying a known amount of heat to the soil and monitoring the temperature evolution, which is primarily dependent on the soil moisture content. The use of both methods, which is called t...

  11. Trinocular Calibration Method Based on Binocular Calibration

    Directory of Open Access Journals (Sweden)

    CAO Dan-Dan

    2012-10-01

    Full Text Available In order to solve the self-occlusion problem in plane-based multi-camera calibration system and expand the measurement range, a tri-camera vision system based on binocular calibration is proposed. The three cameras are grouped into two pairs, while the public camera is taken as the reference to build the global coordinate. By calibration of the measured absolute distance and the true absolute distance, global calibration is realized. The MRE (mean relative error of the global calibration of the two camera pairs in the experiments can be as low as 0.277% and 0.328% respectively. Experiment results show that this method is feasible, simple and effective, and has high precision.

  12. Evaluation of the sap flow using heat pulse method to determine transpiration of the Populus euphratica canopy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiaoyou; KANG Ersi; ZHOU Maoxian

    2007-01-01

    The sap flow of the sampled Populus euphratica stems at different radial depths and directions had been studied in Ejina Oasis,in the lower reaches of the Heihe River.Based on sap flow measurements,the transpiration of the entire canopy was calculated.Results showed a linear correlation between the sap flow and the sapwood area of the P.euphratica.Through the analysis of the diameter at breast height in the sample plot,it was found that the distribution of the diameters and the corresponding sapwood area was exponentially correlated,with the coefficient of correlation being 0.976,7.The calculated transpiration of the Populus euphratica canopy was 214.9 mm based on the specific conductivity method.

  13. New method for calibration of sun photometers

    Institute of Scientific and Technical Information of China (English)

    H.H.Asadov; I.G.Chobanzadeh

    2009-01-01

    A new method for calibration of sun photometers based on Bouguer-Beer law is proposed.The developed basic equation of calibration makes it possible to formulate the derivative methods of calibration on the basis of photometric measurements upon optical air masses,the ratio of which is an integer number.

  14. Heat pulse propagation in chaotic 3-dimensional magnetic fields

    OpenAIRE

    del-Castillo-Negrete, D.; Blazevski, D.

    2014-01-01

    Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The rol...

  15. Heat pulse propagation in chaotic 3-dimensional magnetic fields

    CERN Document Server

    del-Castillo-Negrete, D

    2014-01-01

    Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The role of reversed shear configurations on pulse propagation. In all the cases considered there are no magnetic flux surfaces. However, radial transport is observed to depend strongly on $\\epsilon$ due to the presence of high-order magnetic islands and Cantori that act as quasi-transport barriers that preclude the radial penetration of heat pulses within physically relevant time scale. The dependence of the magnetic field connection length, $\\ell_B$, on $\\epsilon$ is studied in detail. The decay rate of the temperature maximum...

  16. Heat pulse propagation studies in JET

    International Nuclear Information System (INIS)

    Heat pulse propagation (HPP) studies in JET have been carried out using a twelve-channel electron cyclotron emission grating (ECE) polychromator. Emphasis is placed on the behaviour of the heat pulse under strong auxiliary heating. The conventional diffusive model for the data-interpretation has been extended so as to take into account the source- and sink terms in the electron power balance equation. It is concluded that the heat pulse is governed by an 'incremental' heat diffusivity, which is related to the incremental confinement time. Experimental results which were obtained during operation of JET are presented, including values of HPP during ohmic heating and HPP during auxiliary heating. These experimental results are discussed with respect to the incremental heat diffusivity. Finally the results of this work are considered in relation to the study of anomalous transport in tokamaks. (U.K.)

  17. Influence of stem temperature changes on heat pulse sap flux density measurements.

    Science.gov (United States)

    Vandegehuchte, Maurits W; Burgess, Stephen S O; Downey, Alec; Steppe, Kathy

    2015-04-01

    While natural spatial temperature gradients between measurement needles have been thoroughly investigated for continuous heat-based sap flow methods, little attention has been given to how natural changes in stem temperature impact heat pulse-based methods through temporal rather than spatial effects. By modelling the theoretical equation for both an ideal instantaneous pulse and a step pulse and applying a finite element model which included actual needle dimensions and wound effects, the influence of a varying stem temperature on heat pulse-based methods was investigated. It was shown that the heat ratio (HR) method was influenced, while for the compensation heat pulse and Tmax methods changes in stem temperatures of up to 0.002 °C s(-1) did not lead to significantly different results. For the HR method, rising stem temperatures during measurements led to lower heat pulse velocity values, while decreasing stem temperatures led to both higher and lower heat pulse velocities, and to imaginary results for high flows. These errors of up to 40% can easily be prevented by including a temperature correction in the data analysis procedure, calculating the slope of the natural temperature change based on the measured temperatures before application of the heat pulse. Results of a greenhouse and outdoor experiment on Pinus pinea L. show the influence of this correction on low and average sap flux densities.

  18. Measuring sap flow and stem water content in trees: a critical analysis and development of a new heat pulse method (Sapflow+)

    OpenAIRE

    Vandegehuchte, Maurits

    2013-01-01

    Just as carbon, water is indispensable for plants to develop and grow. A lack of water causes turgor loss in plant cells which prevents further expansion of these cells and the coupled incorporation of carbon sources in the cell wall. This inhibits growth and, if this water scarcity continues, plant dimensions such as the stem diameter will start to decrease. Finally the plant will lose its vital functions and die. Worldwide, sap flow methods are applied to monitor plant water status and v...

  19. Systems and methods of eye tracking calibration

    DEFF Research Database (Denmark)

    2014-01-01

    Methods and systems to facilitate eye tracking control calibration are provided. One or more objects are displayed on a display of a device, where the one or more objects are associated with a function unrelated to a calculation of one or more calibration parameters. The one or more calibration...... parameters relate to a calibration of a calculation of gaze information of a user of the device, where the gaze information indicates where the user is looking. While the one or more objects are displayed, eye movement information associated with the user is determined, which indicates eye movement of one...... or more eye features associated with at least one eye of the user. The eye movement information is associated with a first object location of the one or more objects. The one or more calibration parameters are calculated based on the first object location being associated with the eye movement information....

  20. Ion Beam Energy Calibration Method for Accelerator

    International Nuclear Information System (INIS)

    Ion beam energy calibration methods, i e : nuclear reaction method, magnetic field method and calorimeter method were elaborated and studied from its advantage and disadvantage in this paper. Ion beam energy calibration method for accelerator using the method of magnetic field on 3 MV Tandem Accelerator have been carried out at Tiara, JAERI, Japan. The result showed that the energy of ion beam current is 43.56 keV. The result of study conclude that nuclear reaction method generally used to calibrate ion beam energy at the accelerator of energy larger than 2 MeV, calorimetric method for the accelerator electron including linac, magnetic field method for all particle type of accelerator. (author)

  1. A transmission calibration method for superconducting resonators

    CERN Document Server

    Cataldo, Giuseppe; Barrentine, Emily M; Brown, Ari D; Moseley, Samuel H; U-Yen, Kongpop

    2014-01-01

    A method is proposed and experimentally explored for \\textit{in-situ} calibration of complex transmission data for superconducting microwave resonators. This cryogenic calibration method accounts for the instrumental transmission response between the vector network analyzer reference plane and the device calibration plane. Once calibrated, the observed resonator response was modeled in detail by two approaches. The first, a phenomenological model based on physically realizable rational functions, enables the extraction of multiple resonance frequencies and widths for coupled resonators without explicit specification of the circuit network. In the second, an ABCD-matrix representation for the distributed transmission line circuit is used to model the observed response from the characteristic impedance and propagation constant. When used in conjunction with electromagnetic simulations, the kinetic inductance fraction can be determined with this method with an accuracy of 2%. Datasets for superconducting microst...

  2. A Method to Test Model Calibration Techniques

    Energy Technology Data Exchange (ETDEWEB)

    Judkoff, Ron; Polly, Ben; Neymark, Joel

    2016-08-26

    This paper describes a method for testing model calibration techniques. Calibration is commonly used in conjunction with energy retrofit audit models. An audit is conducted to gather information about the building needed to assemble an input file for a building energy modeling tool. A calibration technique is used to reconcile model predictions with utility data, and then the 'calibrated model' is used to predict energy savings from a variety of retrofit measures and combinations thereof. Current standards and guidelines such as BPI-2400 and ASHRAE-14 set criteria for 'goodness of fit' and assume that if the criteria are met, then the calibration technique is acceptable. While it is logical to use the actual performance data of the building to tune the model, it is not certain that a good fit will result in a model that better predicts post-retrofit energy savings. Therefore, the basic idea here is that the simulation program (intended for use with the calibration technique) is used to generate surrogate utility bill data and retrofit energy savings data against which the calibration technique can be tested. This provides three figures of merit for testing a calibration technique, 1) accuracy of the post-retrofit energy savings prediction, 2) closure on the 'true' input parameter values, and 3) goodness of fit to the utility bill data. The paper will also discuss the pros and cons of using this synthetic surrogate data approach versus trying to use real data sets of actual buildings.

  3. Field performance of the heat pulse flow meter: Experiences and recommendations

    Science.gov (United States)

    Busse, J.; Paillet, F. L.; Hossack, A.; Bringemeier, D.; Scheuermann, A.; Li, L.

    2016-03-01

    A large extent of groundwater flow in fractured aquifers follows fractures and cleats. The heat pulse flow meter allows the localisation and quantification of in- and outflow along borehole profiles through field measurements and subsequent inverse modelling. In this paper the method is presented and its feasibility is discussed based on the experiences gained from two different field sites. Field work was undertaken on two sites on the East Coast of Australia under different conditions leading to different outcomes. The experiences with the heat pulse flow meter method and concluding recommendations are reported to help improve the performance of the method.

  4. Modulated heat pulse propagation and partial transport barriers in chaotic magnetic fields

    CERN Document Server

    del-Castillo-Negrete, D

    2016-01-01

    Direct numerical simulations of the time dependent parallel heat transport equation modeling heat pulses driven by power modulation in 3-dimensional chaotic magnetic fields are presented. The numerical method is based on the Fourier formulation of a Lagrangian-Green's function method that provides an accurate and efficient technique for the solution of the parallel heat transport equation in the presence of harmonic power modulation. The numerical results presented provide conclusive evidence that even in the absence of magnetic flux surfaces, chaotic magnetic field configurations with intermediate levels of stochasticity exhibit transport barriers to modulated heat pulse propagation. In particular, high-order islands and remnants of destroyed flux surfaces (Cantori) act as partial barriers that slow down or even stop the propagation of heat waves at places where the magnetic field connection length exhibits a strong gradient. Results on modulated heat pulse propagation in fully stochastic fields and across m...

  5. An Optimal Calibration Method for a MEMS Inertial Measurement Unit

    Directory of Open Access Journals (Sweden)

    Bin Fang

    2014-02-01

    Full Text Available An optimal calibration method for a micro-electro-mechanical inertial measurement unit (MIMU is presented in this paper. The accuracy of the MIMU is highly dependent on calibration to remove the deterministic errors of systematic errors, which also contain random errors. The overlapping Allan variance is applied to characterize the types of random error terms in the measurements. The calibration model includes package misalignment error, sensor-to-sensor misalignment error and bias, and a scale factor is built. The new concept of a calibration method, which includes a calibration scheme and a calibration algorithm, is proposed. The calibration scheme is designed by D-optimal and the calibration algorithm is deduced by a Kalman filter. In addition, the thermal calibration is investigated, as the bias and scale factor varied with temperature. The simulations and real tests verify the effectiveness of the proposed calibration method and show that it is better than the traditional method.

  6. A webcam photogrammetric method for robot calibration

    Science.gov (United States)

    Sargeant, Ben; Hosseininaveh, Ali A.; Erfani, Tohid; Robson, Stuart; Boehm, Jan

    2013-04-01

    This paper describes a strategy for accurate robot calibration using close range photogrammetry. A 5-DoF robot has been designed for placement of two web cameras relative to an object. To ensure correct camera positioning, the robot is calibrated using the following strategy. First, a Denavit-Hartenberg method is used to generate a general kinematic robot model. A set of reference frames are defined relative to each joint and each of the cameras, transformation matrices are then produced to represent change in position and orientation between frames in terms of joint positions and unknown parameters. The complete model is extracted by multiplying these matrices. Second, photogrammetry is used to estimate the postures of both cameras. A set of images are captured of a calibration fixture from different robot poses. The camera postures are then estimated using bundle adjustment. Third, the kinematic parameters are estimated using weighted least squares. For each pose a set of equations are extracted from the model and the unknown parameters are estimated in an iterative procedure. Finally these values are substituted back into the original model. This final model is tested using forward kinematics by comparing the model's predicted camera postures for given joint positions to the values obtained through photogrammetry. Inverse kinematics is performed using both least squares and particle swarm optimisation and these techniques are contrasted. Results demonstrate that this photogrammetry approach produces a reliable and accurate model of the robot that can be used with both least squares and particle swarm optimisation for robot control.

  7. Modulated heat pulse propagation and partial transport barriers in chaotic magnetic fields

    Science.gov (United States)

    del-Castillo-Negrete, Diego; Blazevski, Daniel

    2016-04-01

    Direct numerical simulations of the time dependent parallel heat transport equation modeling heat pulses driven by power modulation in three-dimensional chaotic magnetic fields are presented. The numerical method is based on the Fourier formulation of a Lagrangian-Green's function method that provides an accurate and efficient technique for the solution of the parallel heat transport equation in the presence of harmonic power modulation. The numerical results presented provide conclusive evidence that even in the absence of magnetic flux surfaces, chaotic magnetic field configurations with intermediate levels of stochasticity exhibit transport barriers to modulated heat pulse propagation. In particular, high-order islands and remnants of destroyed flux surfaces (Cantori) act as partial barriers that slow down or even stop the propagation of heat waves at places where the magnetic field connection length exhibits a strong gradient. Results on modulated heat pulse propagation in fully stochastic fields and across magnetic islands are also presented. In qualitative agreement with recent experiments in large helical device and DIII-D, it is shown that the elliptic (O) and hyperbolic (X) points of magnetic islands have a direct impact on the spatio-temporal dependence of the amplitude of modulated heat pulses.

  8. Modulated heat pulse propagation and partial transport barriers in chaotic magnetic fields

    OpenAIRE

    del-Castillo-Negrete, D.; Blazevski, D.

    2016-01-01

    Direct numerical simulations of the time dependent parallel heat transport equation modeling heat pulses driven by power modulation in 3-dimensional chaotic magnetic fields are presented. The numerical method is based on the Fourier formulation of a Lagrangian-Green's function method that provides an accurate and efficient technique for the solution of the parallel heat transport equation in the presence of harmonic power modulation. The numerical results presented provide conclusive evidence...

  9. Calibration method for a central catadioptric-perspective camera system.

    Science.gov (United States)

    He, Bingwei; Chen, Zhipeng; Li, Youfu

    2012-11-01

    A central catadioptric-perspective camera system is widely used nowadays. A critical problem is that current calibration methods cannot determine the extrinsic parameters between the central catadioptric camera and a perspective camera effectively. We present a novel calibration method for a central catadioptric-perspective camera system, in which the central catadioptric camera has a hyperbolic mirror. Two cameras are used to capture images of one calibration pattern at different spatial positions. A virtual camera is constructed at the origin of the central catadioptric camera and faced toward the calibration pattern. The transformation between the virtual camera and the calibration pattern could be computed first and the extrinsic parameters between the central catadioptric camera and the calibration pattern could be obtained. Three-dimensional reconstruction results of the calibration pattern show a high accuracy and validate the feasibility of our method.

  10. Calibration methods for rotating shadowband irradiometers and evaluation of calibration duration

    Directory of Open Access Journals (Sweden)

    W. Jessen

    2015-10-01

    Full Text Available Resource assessment for Concentrated Solar Power (CSP needs accurate Direct Normal Irradiance (DNI measurements. An option for such measurement campaigns are Rotating Shadowband Irradiometers (RSIs with a thorough calibration. Calibration of RSIs and Si-sensors in general is complex because of the inhomogeneous spectral response of such sensors and incorporates the use of several correction functions. A calibration for a given atmospheric condition and air mass might not work well for a different condition. This paper covers procedures and requirements for two calibration methods for the calibration of Rotating Shadowband Irradiometers. The necessary duration of acquisition of test measurements is examined in regard to the site specific conditions at Plataforma Solar de Almeria (PSA in Spain. Data sets of several long-term calibration periods from PSA are used to evaluate the deviation of results from calibrations with varying duration from the long-term result. The findings show that seasonal changes of environmental conditions are causing small but noticeable fluctuation of calibration results. Certain periods (i.e. November to January and April to May show a higher likelihood of particularly adverse calibration results. These effects can partially be compensated by increasing the inclusions of measurements from outside these periods. Consequently, the duration of calibrations at PSA can now be selected depending on the time of the year in which measurements are commenced.

  11. Outdoor relative radiometric calibration method using gray scale targets

    Institute of Scientific and Technical Information of China (English)

    DUAN; YiNi; YAN; Lei; YANG; Bin; JING; Xin; CHEN; Wei

    2013-01-01

    The radiometric calibration of remote sensors is a basis and prerequisite of information quantification in remote sensing. This paper proposes a method for outdoor relative radiometric calibration using gray scale targets. In this method, the idea of two substitutions is adopted. Sunlight is used to replace the integrating sphere light source, and gray scale targets are used to re-place the diffuser. In this way, images at different radiance levels obtained outdoors can calculate the relative radiometric cali-bration coefficients using the least square method. The characteristics of this method are as follows. Firstly, compared with la-boratory calibration, it greatly reduces the complexity of the calibration method and the test cost. Secondly, compared with the existing outdoor relative radiometric calibration of a single radiance level, it uses test images of different radiance levels to re-duce errors. Thirdly, it is easy to operate with fewer environmental requirements, has obvious advantages in the rapid calibra-tion of airborne remote sensors before or after flight and is practical in engineering. This paper theoretically and experimental-ly proves the feasibility of this method. Calibration experiments were conducted on the wide-view multispectral imager (WVMI) using this method, and the precision of this method was evaluated by analyzing the corrected images of large uniform targets on ground. The experiment results have demonstrated that the new method is effective and its precision meets the re-quirement of the absolute radiometric calibration.

  12. Research radiometric calibration quantitative transfer methods between internal and external

    Science.gov (United States)

    Guo, Ju Guang; Ma, Yong hui; Zhang, Guang; Yang, Zhi hui

    2015-10-01

    This paper puts forward a method by realizing the internal and external radiation calibration transfer for infrared radiation characteristics quantitative measuring system. Through technological innovation and innovation application to establish a theoretical model of the corresponding radiated transfer method. This method can be well in engineering application for technology conversion process of radiometric calibration that with relatively simple and effective calibration in the half light path radiation instead of complex difficult whole optical path radiometric calibration. At the same time, it also will provide the basis of effective support to further carry out the target radiated characteristics quantitative measurement and application for ground type infrared radiated quantitative measuring system.

  13. Doppler calibration method for Spectral Domain OCT spectrometers

    NARCIS (Netherlands)

    D.J. Faber; T.G. van Leeuwen

    2009-01-01

    We present a calibration method for SD-OCT domain spectrometers based on the M-scan of a moving mirror. This method allows determination of the wavenumber sampling increment which determines the depth axis assigned to the structural image. It also allows wavelength calibration of individual pixels w

  14. Simultaneous multi-headed imager geometry calibration method

    Science.gov (United States)

    Tran, Vi-Hoa; Meikle, Steven Richard; Smith, Mark Frederick

    2008-02-19

    A method for calibrating multi-headed high sensitivity and high spatial resolution dynamic imaging systems, especially those useful in the acquisition of tomographic images of small animals. The method of the present invention comprises: simultaneously calibrating two or more detectors to the same coordinate system; and functionally correcting for unwanted detector movement due to gantry flexing.

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

    Science.gov (United States)

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

    2012-01-01

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

  16. Controlled calibration method for laser induced breakdown spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Li Wang; Chijian Zhang; Yuan Feng

    2008-01-01

    Laser induced breakdown spectroscopy (LIBS) is a potential technique for rapid analysis of samples present in solids, gases and liquids. In the last two decades it was an object of extensive studies. Controlled calibration method used to analysis the LIBS spectra is investigated. Compared with the inner calibration and calibration-free (CF) methods, this new method overcomes "matrix effect", and demonstrates a better ability to cope with the spectra. It is used to analyze natural soil, and errors of the concentration are decreased about 5%. The result shows that the new method is feasible and accurate.

  17. Radioactive standards and calibration methods for contamination monitoring instruments

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Makoto [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-06-01

    Contamination monitoring in the facilities for handling unsealed radioactive materials is one of the most important procedures for radiation protection as well as radiation dose monitoring. For implementation of the proper contamination monitoring, radiation measuring instruments should not only be suitable to the purpose of monitoring, but also be well calibrated for the objective qualities of measurement. In the calibration of contamination monitoring instruments, quality reference activities need to be used. They are supplied in different such as extended sources, radioactive solutions or radioactive gases. These reference activities must be traceable to the national standards or equivalent standards. On the other hand, the appropriate calibration methods must be applied for each type of contamination monitoring instruments. In this paper, the concepts of calibration for contamination monitoring instruments, reference sources, determination methods of reference quantities and practical calibration methods of contamination monitoring instruments, including the procedures carried out in Japan Atomic Energy Research Institute and some relevant experimental data. (G.K.)

  18. The Study of Heat Pulse Propagation on HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    许祎; 胡立群; 万宝年; 石跃江

    2003-01-01

    The propagation of heat pulses originating from sawtooth activity has been studied on the HT-7 tokamak. Two theoretical models are used for determining electron heat diffusivity from the experimental data measured by a diagnostic system of soft x-ray diode-array. The results the signal-to-noise (S/N) ratio of the original signals, over a few tens of sawteeth are averaged to generate nice waveforms. The space-time evolution is found to be diffusive in character, which is consistent with the theoretical model. The electron heat diffusivity determined from heat pulse propagation is larger than that determined from background plasma power balance. The variation of Xe in different discharge phases has been also discussed.

  19. Scatterometer-Calibrated Stability Verification Method

    Science.gov (United States)

    McWatters, Dalia A.; Cheetham, Craig M.; Huang, Shouhua; Fischman, Mark A.; CHu, Anhua J.; Freedman, Adam P.

    2011-01-01

    The requirement for scatterometer-combined transmit-receive gain variation knowledge is typically addressed by sampling a portion of the transmit signal, attenuating it with a known-stable attenuation, and coupling it into the receiver chain. This way, the gain variations of the transmit and receive chains are represented by this loop-back calibration signal, and can be subtracted from the received remote radar echo. Certain challenges are presented by this process, such as transmit and receive components that are outside of this loop-back path and are not included in this calibration, as well as the impracticality for measuring the transmit and receive chains stability and post fabrication separately, without the resulting measurement errors from the test set up exceeding the requirement for the flight instrument. To cover the RF stability design challenge, the portions of the scatterometer that are not calibrated by the loop-back, (e.g., attenuators, switches, diplexers, couplers, and coaxial cables) are tightly thermally controlled, and have been characterized over temperature to contribute less than 0.05 dB of calibration error over worst-case thermal variation. To address the verification challenge, including the components that are not calibrated by the loop-back, a stable fiber optic delay line (FODL) was used to delay the transmitted pulse, and to route it into the receiver. In this way, the internal loopback signal amplitude variations can be compared to the full transmit/receive external path, while the flight hardware is in the worst-case thermal environment. The practical delay for implementing the FODL is 100 s. The scatterometer pulse width is 1 ms so a test mode was incorporated early in the design phase to scale the 1 ms pulse at 100-Hz pulse repetition interval (PRI), by a factor of 18, to be a 55 s pulse with 556 s PRI. This scaling maintains the duty cycle, thus maintaining a representative thermal state for the RF components. The FODL consists

  20. Analysis of Nigeria research reactor-1 thermal power calibration methods

    Energy Technology Data Exchange (ETDEWEB)

    Agbo, Sunday Arome; Ahmed, Yusuf Aminu; Ewa, Ita Okon; Jibrin, Yahaya [Ahmadu Bello University, Zaria (Nigeria)

    2016-06-15

    This paper analyzes the accuracy of the methods used in calibrating the thermal power of Nigeria Research Reactor-1 (NIRR-1), a low-power miniature neutron source reactor located at the Centre for Energy Research and Training, Ahmadu Bello University, Zaria, Nigeria. The calibration was performed at three different power levels: low power (3.6 kW), half power (15 kW), and full power (30 kW). Two methods were used in the calibration, namely, slope and heat balance methods. The thermal power obtained by the heat balance method at low power, half power, and full power was 3.7 ± 0.2 kW, 15.2 ± 1.2 kW, and 30.7 ± 2.5 kW, respectively. The thermal power obtained by the slope method at half power and full power was 15.8 ± 0.7 kW and 30.2 ± 1.5 kW, respectively. It was observed that the slope method is more accurate with deviations of 4% and 5% for calibrations at half and full power, respectively, although the linear fit (slope method) on average temperature-rising rates during the thermal power calibration procedure at low power (3.6 kW) is not fitting. As such, the slope method of power calibration is not suitable at lower power for NIRR-1.

  1. Calibration method of HLS's sensor used in SSRF

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The site of Shanghai Synchrotron Radiation Facility (SSRF) is of complicated geological conditions, and a system to monitor the uneven subsidence of foundation and key parts (different kinds of magnets) of the accelerators is a necessity. Considering actual conditions of the accelerator structure and the assembling place, a new type of sensor of hydrostatic levelling system (HLS) has been designed. In order to obtain the required measurement accuracy, every HLS's sensor was strictly calibrated. In this paper, we introduce the special calibration method to establish the HLS. The method has been used in the calibration for vessel sensor for SSRF.

  2. Calibration methods for ECE systems with microwave sources

    International Nuclear Information System (INIS)

    The authors investigated the feasibility of two methods for calibration of electron cyclotron emission (ECE) systems, both based on the use of a microwave source. In the first method -called the Antenna Pattern Integration (API) method - the microwave source is scanned in space, so as to simulate a large - area - blackbody -source. In the second method -called the Untuned Cavity (UC) method -an untuned cavity, fed by the microwave source, is used to simulate a blackbody. For both methods, the hardware required to perform partly automated calibrations was developed. The microwave based methods were compared with a large area blackbody calibration on two different ECE systems, a Michelson interferometer and a grating polychromator. The API method was found to be more successful than the UC method. (author)

  3. Calibration of omnidirectional cameras in practice: A comparison of methods

    OpenAIRE

    Puig, Luis; Bermúdez, Jesús; Sturm, Peter; Guerrero, Josechu

    2012-01-01

    International audience Omnidirectional cameras are becoming increasingly popular in computer vision and robotics. Camera calibration is a step before performing any task involving metric scene measurement, required in nearly all robotics tasks. In recent years many different methods to calibrate central omnidirectional cameras have been developed, based on different camera models and often limited to a specific mirror shape. In this paper we review the existing methods designed to calibrat...

  4. Method for Accurately Calibrating a Spectrometer Using Broadband Light

    Science.gov (United States)

    Simmons, Stephen; Youngquist, Robert

    2011-01-01

    A novel method has been developed for performing very fine calibration of a spectrometer. This process is particularly useful for modern miniature charge-coupled device (CCD) spectrometers where a typical factory wavelength calibration has been performed and a finer, more accurate calibration is desired. Typically, the factory calibration is done with a spectral line source that generates light at known wavelengths, allowing specific pixels in the CCD array to be assigned wavelength values. This method is good to about 1 nm across the spectrometer s wavelength range. This new method appears to be accurate to about 0.1 nm, a factor of ten improvement. White light is passed through an unbalanced Michelson interferometer, producing an optical signal with significant spectral variation. A simple theory can be developed to describe this spectral pattern, so by comparing the actual spectrometer output against this predicted pattern, errors in the wavelength assignment made by the spectrometer can be determined.

  5. A review of control rod calibration methods for irradiated AGRs

    International Nuclear Information System (INIS)

    Methods of calibrating control rods with particular reference to irradiated CAGR are surveyed. Some systematic spatial effects are found and an estimate of their magnitude made. It is concluded that control rod oscillation provides a promising method of calibrating rods at power which is as yet untried on CAGR. Also the rod drop using inverse kinetics provides a rod calibration but spatial effects may be large and these would be difficult to correct theoretically. The pulsed neutron technique provides a calibration route with small errors due to spatial effects provided a suitable K-tube can be developed. The xenon transient method is shown to have statial effects which have not needed consideration in earlier reactors but which in CAGR would need very careful evaluation. (author)

  6. A Statistic-Based Calibration Method for TIADC System

    Directory of Open Access Journals (Sweden)

    Kuojun Yang

    2015-01-01

    Full Text Available Time-interleaved technique is widely used to increase the sampling rate of analog-to-digital converter (ADC. However, the channel mismatches degrade the performance of time-interleaved ADC (TIADC. Therefore, a statistic-based calibration method for TIADC is proposed in this paper. The average value of sampling points is utilized to calculate offset error, and the summation of sampling points is used to calculate gain error. After offset and gain error are obtained, they are calibrated by offset and gain adjustment elements in ADC. Timing skew is calibrated by an iterative method. The product of sampling points of two adjacent subchannels is used as a metric for calibration. The proposed method is employed to calibrate mismatches in a four-channel 5 GS/s TIADC system. Simulation results show that the proposed method can estimate mismatches accurately in a wide frequency range. It is also proved that an accurate estimation can be obtained even if the signal noise ratio (SNR of input signal is 20 dB. Furthermore, the results obtained from a real four-channel 5 GS/s TIADC system demonstrate the effectiveness of the proposed method. We can see that the spectra spurs due to mismatches have been effectively eliminated after calibration.

  7. Calibrations of pocket dosemeters using a comparison method

    International Nuclear Information System (INIS)

    This monograph is dedicated mainly to the calibration of pocket dosemeters. Various types of radiation sources used in hospitals and different radiation detectors with emphasis on ionization chambers are briefly presented. Calibration methods based on the use of a reference dosemeter were developed to calibrate all pocket dosemeters existing at the Radiation Physics and Metrology Laboratory. Some of these dosemeters were used in personnel dosimetry at hospitals. Moreover, a study was realized about factors that affect the measurements with pocket dosemeters in the long term, such as discharges due to cosmic radiation. A DBASE IV program was developed to store the information included in the hospital's registry

  8. A New Method to Calibrate Robot Visual Measurement System

    OpenAIRE

    Yali Wang; Zhenzhong Wei; Mingwei Shao; Guangjun Zhang

    2013-01-01

    This paper presents a new method to calibrate the robot visual measurement system. In the paper, a laser tracker is used to calibrate the robot twist angles. Each axis of the robot is moved to many positions and the positions measured by the laser tracker fit a plane. The normal vectors of the planes are the directions of the axes. According to the definition of the robot kinematics model parameters, the errors of the twist angles can be calculated. The joint angles zero offsets are calibrate...

  9. IMPROVED CALIBRATION METHOD FOR AIRBORNE ATI-SAR BASELINE

    Institute of Scientific and Technical Information of China (English)

    Wang Xin; Hong Jun

    2012-01-01

    Airborne Along-Track Interferometric Synthetic Aperture Radar (ATI-SAR) baseline error is a main error resource affecting the precision of velocity measurement of moving objects and therefore should be calibrated externally.The Jet Propulsion Laboratory (JPL) has proposed a calibration scheme for tasks of PacRim98 and PacRim2000 based on several static objects on the ground.In this paper,the influence of phase center uncertainty on baseline determination by using PacRim method proposed by JPL is analyzed.According to the analysis,the phase center uncertainty can cause a constant part of error to the result of baseline calibration.In order to deal with this problem,an improved calibration method on the basis of sensitivity equations and some ground moving targets,whose velocities are already known,is proposed in this paper.The simulation results show that our proposed calibration method has improved the accuracy of baseline calibration and has obviously prohibited the effect of antennas' phase center uncertainty.

  10. Two Methods for Self Calibration of Digital Camera

    Science.gov (United States)

    Sampath, A.; Moe, D.; Christopherson, J.

    2012-07-01

    Photogrammetric mapping using Commercial of the Shelf (COTS) cameras is becoming more popular. Their popularity is augmented by the increasing use of Unmanned Aerial Vehicles (UAV) as a platform for mapping. The mapping precision of these methods can be increased by using a calibrated camera. The USGS/EROS has developed an inexpensive, easy to use method, particularly for calibrating short focal length cameras. The method builds on a self-calibration procedure developed for the USGS EROS Data Center by Pictometry (and augmented by Dr. C.S Fraser), that uses a series of coded targets. These coded targets form different patterns that are imaged from nine different locations with differing camera orientations. A free network solution using collinearity equations is used to determine the calibration parameters. For the smaller focal length COTS cameras, the USGS has developed a procedure that uses a small prototype box that contains these coded targets. The design of the box is discussed, along with best practices for calibration procedure. Results of calibration parameters obtained using the box are compared with the parameters obtained using more established standard procedures.

  11. Comparison of different calibration methods suited for calibration problems with many variables

    DEFF Research Database (Denmark)

    Holst, Helle

    1992-01-01

    This paper describes and compares different kinds of statistical methods proposed in the literature as suited for solving calibration problems with many variables. These are: principal component regression, partial least-squares, and ridge regression. The statistical techniques themselves do not...

  12. Site characterization for calibration of radiometric sensors using vicarious method

    Science.gov (United States)

    Parihar, Shailesh; Rathore, L. S.; Mohapatra, M.; Sharma, A. K.; Mitra, A. K.; Bhatla, R.; Singh, R. S.; Desai, Yogdeep; Srivastava, Shailendra S.

    2016-05-01

    Radiometric performances of earth observation satellite/sensors vary from ground pre-launch calibration campaign to post launch period extended to lifetime of the satellite due to launching vibrations. Therefore calibration is carried out worldwide through various methods throughout satellite lifetime. In India Indian Space Research Organization (ISRO) calibrates the sensor of Resourcesat-2 satellite by vicarious method. One of these vicarious calibration methods is the reflectance-based approach that is applied in this study for radiometric calibration of sensors on-board Resouresat-2 satellite. The results of ground-based measurement of atmospheric conditions and surface reflectance are made at Bap, Rajasthan Calibration/Validation (Cal/Val) site. Cal/Val observations at site were carried out with hyper-spectral Spectroradiometer covering spectral range of 350nm- 2500nm for radiometric characterization of the site. The Sunphotometer/Ozonometer for measuring the atmospheric parameters has also been used. The calibrated radiance is converted to absolute at-sensor spectral reflectance and Top-Of-Atmosphere (TOA) radiance. TOA radiance was computed using radiative transfer model `Second simulation of the satellite signal in the solar spectrum' (6S), which can accurately simulate the problems introduced by the presence of the atmosphere along the path from Sun to target (surface) to Sensor. The methodology for band averaged reflectance retrieval and spectral reflectance fitting process are described. Then the spectral reflectance and atmospheric parameters are put into 6S code to predict TOA radiance which compare with Resourcesat-2 radiance. Spectral signature and its reflectance ratio indicate the uniformity of the site. Thus the study proves that the selected site is suitable for vicarious calibration of sensor of Resourcesat-2. Further the study demonstrates the procedure for similar exercise for site selection for Cal/Val analysis of other satellite over India

  13. Method and apparatus for calibrating a linear variable differential transformer

    Science.gov (United States)

    Pokrywka, Robert J.

    2005-01-18

    A calibration apparatus for calibrating a linear variable differential transformer (LVDT) having an armature positioned in au LVDT armature orifice, and the armature able to move along an axis of movement. The calibration apparatus includes a heating mechanism with an internal chamber, a temperature measuring mechanism for measuring the temperature of the LVDT, a fixture mechanism with an internal chamber for at least partially accepting the LVDT and for securing the LVDT within the heating mechanism internal chamber, a moving mechanism for moving the armature, a position measurement mechanism for measuring the position of the armature, and an output voltage measurement mechanism. A method for calibrating an LVDT, including the steps of: powering the LVDT; heating the LVDT to a desired temperature; measuring the position of the armature with respect to the armature orifice; and measuring the output voltage of the LVDT.

  14. An Accurate Projector Calibration Method Based on Polynomial Distortion Representation

    Directory of Open Access Journals (Sweden)

    Miao Liu

    2015-10-01

    Full Text Available In structure light measurement systems or 3D printing systems, the errors caused by optical distortion of a digital projector always affect the precision performance and cannot be ignored. Existing methods to calibrate the projection distortion rely on calibration plate and photogrammetry, so the calibration performance is largely affected by the quality of the plate and the imaging system. This paper proposes a new projector calibration approach that makes use of photodiodes to directly detect the light emitted from a digital projector. By analyzing the output sequence of the photoelectric module, the pixel coordinates can be accurately obtained by the curve fitting method. A polynomial distortion representation is employed to reduce the residuals of the traditional distortion representation model. Experimental results and performance evaluation show that the proposed calibration method is able to avoid most of the disadvantages in traditional methods and achieves a higher accuracy. This proposed method is also practically applicable to evaluate the geometric optical performance of other optical projection system.

  15. A New Full Pose Measurement Method for Robot Calibration

    Directory of Open Access Journals (Sweden)

    Hee-Jun Kang

    2013-07-01

    Full Text Available Identification of robot kinematic errors during the calibration process often requires accurate full pose measurements (position and orientation of robot end-effectors in Cartesian space. This paper proposes a new method of full pose measurement of robot end-effectors for calibration. This method is based on an analysis of the features of a set of target points (placed on a rotating end-effector on a circular trajectory. The accurate measurement is validated by computational simulation results from the Puma robot. Moreover, experimental calibration and validation results for the Hyundai HA-06 robot prove the effectiveness, correctness, and reliability of the proposed method. This method can be applied to robots that have entirely revolute joints or to robots for which only the last joint is revolute.

  16. Method for out-of-focus camera calibration.

    Science.gov (United States)

    Bell, Tyler; Xu, Jing; Zhang, Song

    2016-03-20

    State-of-the-art camera calibration methods assume that the camera is at least nearly in focus and thus fail if the camera is substantially defocused. This paper presents a method which enables the accurate calibration of an out-of-focus camera. Specifically, the proposed method uses a digital display (e.g., liquid crystal display monitor) to generate fringe patterns that encode feature points into the carrier phase; these feature points can be accurately recovered, even if the fringe patterns are substantially blurred (i.e., the camera is substantially defocused). Experiments demonstrated that the proposed method can accurately calibrate a camera regardless of the amount of defocusing: the focal length difference is approximately 0.2% when the camera is focused compared to when the camera is substantially defocused.

  17. A calibration method for PLLs based on transient response

    DEFF Research Database (Denmark)

    Cassia, Marco; Shah, Peter Jivan; Bruun, Erik

    2004-01-01

    A novel method to calibrate the frequency response of a Phase-Locked Loop is presented. The method requires just an additional digital counter and an auxiliary Phase-Frequency Detector (PFD) to measure the natural frequency of the PLL. The measured value can be used to tune the PLL response to th...

  18. A novel calibration method for phase-locked loops

    DEFF Research Database (Denmark)

    Cassia, Marco; Shah, Peter Jivan; Bruun, Erik

    2005-01-01

    A novel method to calibrate the frequency response of a Phase-Locked Loop is presented. The method requires just an additional digital counter to measure the natural frequency of the PLL; moreover it is capable of estimating the static phase offset. The measured value can be used to tune the PLL ...

  19. A Method to Test Model Calibration Techniques: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Judkoff, Ron; Polly, Ben; Neymark, Joel

    2016-09-01

    This paper describes a method for testing model calibration techniques. Calibration is commonly used in conjunction with energy retrofit audit models. An audit is conducted to gather information about the building needed to assemble an input file for a building energy modeling tool. A calibration technique is used to reconcile model predictions with utility data, and then the 'calibrated model' is used to predict energy savings from a variety of retrofit measures and combinations thereof. Current standards and guidelines such as BPI-2400 and ASHRAE-14 set criteria for 'goodness of fit' and assume that if the criteria are met, then the calibration technique is acceptable. While it is logical to use the actual performance data of the building to tune the model, it is not certain that a good fit will result in a model that better predicts post-retrofit energy savings. Therefore, the basic idea here is that the simulation program (intended for use with the calibration technique) is used to generate surrogate utility bill data and retrofit energy savings data against which the calibration technique can be tested. This provides three figures of merit for testing a calibration technique, 1) accuracy of the post-retrofit energy savings prediction, 2) closure on the 'true' input parameter values, and 3) goodness of fit to the utility bill data. The paper will also discuss the pros and cons of using this synthetic surrogate data approach versus trying to use real data sets of actual buildings.

  20. A new method for thread calibration on coordinate measuring machines

    DEFF Research Database (Denmark)

    Carmignato, Simone; De Chiffre, Leonardo

    2003-01-01

    CIRP Annals – Paper proposal temporary reference: P15. This paper presents a new method for the calibration of thread gauges on coordinate measuring machines. The procedure involves scanning of thread profiles using a needle-like probe, achieving traceability by substitution of different thread......-3 gave measuring uncertainties comparable to the values from usual calibration methods on dedicated equipment, e.g. a measuring uncertainty of 1.5 µm was achieved for measurement of the pitch, and 2-2.5 µm for diameter measurements....

  1. A pratical method of data elimination in radiometric calibration

    International Nuclear Information System (INIS)

    The absence of phosphorite standards to uranium radiometric analyses sugests the necessity of intercomparison samples to construct an uranium calibration curve. The intercomparison analysis was performed by delay neutrons, X-rays fluorescence and molecular absorption spectrophotometry in three diferents laboratories. This work intends to stablish rejection criteria for deviating data in order to achieve better precision. Through the comparison from results of the analysis methods, the data outside the confidence intervals, were eliminated. A more accurate calibration curve inside the interval +-1,1% to +-3.0% was obtained with this method. (author)

  2. An Automated Method for Ozonesonde Calibration: New Insights

    Science.gov (United States)

    Schmidlin, F. J.; Hoegger, Bruno A.; Levrat, Gilbert; Baldwin, Tony

    2008-01-01

    An automated method for preparation of the electrochemical concentration cell (ECC) ozonesonde is presented. Development of a computer-controlled system for preparation and calibration of the ECC is an improvement over the manual preparation method, and reduces subjectivity considerably. Preparation measurements in digital form aids analysis of the ECC before release and enhances post-flight data certification. Calibration of ozonesondes over a range of ozone concentrations between 0 mPA and 30 mPA is discussed. This presentation describes the automatic system, gives examples of calibrations. The automated system enables comparison of varying potassium iodide (KI) concentrations that should allow adjustment of earlier ozonesonde data obtained with different KT concentrations used since 1970, i.e., 2, 1.5, 1, and 0.5 percent. Preliminary results indicate ECC accuracy has a strong dependence on the electrolyte concentration and should not be considered linear with altitude.

  3. Fuzzy Interpolation and Other Interpolation Methods Used in Robot Calibrations

    Directory of Open Access Journals (Sweden)

    Ying Bai

    2012-01-01

    Full Text Available A novel interpolation algorithm, fuzzy interpolation, is presented and compared with other popular interpolation methods widely implemented in industrial robots calibrations and manufacturing applications. Different interpolation algorithms have been developed, reported, and implemented in many industrial robot calibrations and manufacturing processes in recent years. Most of them are based on looking for the optimal interpolation trajectories based on some known values on given points around a workspace. However, it is rare to build an optimal interpolation results based on some random noises, and this is one of the most popular topics in industrial testing and measurement applications. The fuzzy interpolation algorithm (FIA reported in this paper provides a convenient and simple way to solve this problem and offers more accurate interpolation results based on given position or orientation errors that are randomly distributed in real time. This method can be implemented in many industrial applications, such as manipulators measurements and calibrations, industrial automations, and semiconductor manufacturing processes.

  4. Flexible Calibration Method for 3D Laser Scanner System

    Institute of Scientific and Technical Information of China (English)

    杨中东; 王鹏; 李晓慧; 孙长库

    2014-01-01

    In this paper, a flexible high-precision calibration method suitable for industrial field was proposed. The complexity of the coordinate transformation was simplified by choosing the camera coordinate system as the unified reference coordinate system. A flexible planar calibration pattern was introduced to the calibration process, which can be arbitrarily placed and from which the known feature points can be extracted to construct other unknown feature points. With the known intrinsic parameters, the laser projector plane equation was fitted by the multi-noncollinear points, which were acquired through the principle of triangulation and the projective invariance of cross ratio. With this method, the strict alignment and multiple times of coordinate transformation can be avoided. Experimental results showed that the arithmetic mean of the root mean square (RMS) error of distance was 0.000 7 mm.

  5. Development of Method for X-band Weather Radar Calibration

    DEFF Research Database (Denmark)

    Nielsen, Jesper Ellerbæk; Thorndahl, Søren Liedtke; Rasmussen, Michael R.

    2013-01-01

    Calibration of the X-band LAWR (Local Area Weather Radar) is traditionally based on an assumed linear relation between the LAWRradar output and the rainfall intensity. However, closer inspections of the data reveal that the validity of this linear assumption is doubtful. Previous studies of this ......Calibration of the X-band LAWR (Local Area Weather Radar) is traditionally based on an assumed linear relation between the LAWRradar output and the rainfall intensity. However, closer inspections of the data reveal that the validity of this linear assumption is doubtful. Previous studies...... of this type of weather radar have also illustrated that the radar commonly has difficulties in estimating high rain rates. Therefore, a new radar–rainfall transformation model and a calibration method have been developed. The new method is based on nonlinear assumptions and is aimed at describing the whole...

  6. Experimental facility and void fraction calibration methods for impedance probes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Fernando L. de; Rocha, Marcelo S., E-mail: floliveira@ipen.br, E-mail: msrocha@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    An experimental facility was designed and constructed with aims of to calibrate a capacitance probe for gas-liquid flow void fraction measurements. The facility is composed of a metallic hack with a vertical 2,300 mm high glass tube with 38 mm ID with stagnant water and compressed air bubbling system simulating the gas phase (vapor). At the lower part, a mixing section with a porous media element releases the air bubbles into the water, and the compressed air flow is measured by two calibrated rotameters. At the upper part a stagnant water tank separates the liquid and gas. Two pressure taps are located near the lower and upper sides of the glass tube for pressure difference measurement. The pressure difference is used for low void fraction values (0-15%) calibration methods, as described in the work. Two electrically controlled quick closing valves are installed between the porous media element and the upward separation tank for high void fraction values measurement (15-50%) used to calibrate the capacitance probe. The experimental facility design, construction, capacitance probe calibration methods and results, as well as flow pattern visualization, are presented. Finally, the capacitance probe will be installed on a natural circulation circuit mounted at the Nuclear Engineering Center (CEN/IPEN/CNEN-SP) for measurement of the instantaneous bulk void. Instantaneous signals generated by the capacitance probe will allow the determination of natural circulation loop global energy balance. (author)

  7. A simple calibration method for mechanically braked cycle ergometers.

    Science.gov (United States)

    Van Praagh, E; Bedu, M; Roddier, P; Coudert, J

    1992-01-01

    The calibration of cycle ergometers should be checked regularly. Some studies have shown calibration errors of more than 40%. A simple, inexpensive calibrating method for mechanically braked cycle ergometers was developed and tried out on a new type of ergocycle. The cycle ergometer was elevated and the crank replaced by a pulley fitted to the shaft. The crank speed (rpm) increased linearly as a function of time when different masses were applied on the pulley. For a given braking force on the cycle ergometer, different accelerations corresponding to the increased pulley forces could be measured. When extrapolating for zero acceleration, it was possible to determine a "limit-force" which allowed the system to be in equilibrium. Additional force creates motion. The same experiments were repeated with increasing braking forces. Using the differently sized gear sprockets of the transmission system, it was possible to calculate the actual force, including all the resistances. The actual force found by the calibrating method was then compared with the indicated force proposed by the manufacturer. With increasing forces, the relative errors decreased from 9.6 to 2.9%. The cycle ergometer calibrated by this technique meets the standards recommended in exercise physiology. PMID:1544728

  8. A stoichiometric calibration method for dual energy computed tomography

    Science.gov (United States)

    Bourque, Alexandra E.; Carrier, Jean-François; Bouchard, Hugo

    2014-04-01

    The accuracy of radiotherapy dose calculation relies crucially on patient composition data. The computed tomography (CT) calibration methods based on the stoichiometric calibration of Schneider et al (1996 Phys. Med. Biol. 41 111-24) are the most reliable to determine electron density (ED) with commercial single energy CT scanners. Along with the recent developments in dual energy CT (DECT) commercial scanners, several methods were published to determine ED and the effective atomic number (EAN) for polyenergetic beams without the need for CT calibration curves. This paper intends to show that with a rigorous definition of the EAN, the stoichiometric calibration method can be successfully adapted to DECT with significant accuracy improvements with respect to the literature without the need for spectrum measurements or empirical beam hardening corrections. Using a theoretical framework of ICRP human tissue compositions and the XCOM photon cross sections database, the revised stoichiometric calibration method yields Hounsfield unit (HU) predictions within less than ±1.3 HU of the theoretical HU calculated from XCOM data averaged over the spectra used (e.g., 80 kVp, 100 kVp, 140 kVp and 140/Sn kVp). A fit of mean excitation energy (I-value) data as a function of EAN is provided in order to determine the ion stopping power of human tissues from ED-EAN measurements. Analysis of the calibration phantom measurements with the Siemens SOMATOM Definition Flash dual source CT scanner shows that the present formalism yields mean absolute errors of (0.3 ± 0.4)% and (1.6 ± 2.0)% on ED and EAN, respectively. For ion therapy, the mean absolute errors for calibrated I-values and proton stopping powers (216 MeV) are (4.1 ± 2.7)% and (0.5 ± 0.4)%, respectively. In all clinical situations studied, the uncertainties in ion ranges in water for therapeutic energies are found to be less than 1.3 mm, 0.7 mm and 0.5 mm for protons, helium and carbon ions respectively, using a generic

  9. A stoichiometric calibration method for dual energy computed tomography

    International Nuclear Information System (INIS)

    The accuracy of radiotherapy dose calculation relies crucially on patient composition data. The computed tomography (CT) calibration methods based on the stoichiometric calibration of Schneider et al (1996 Phys. Med. Biol. 41 111–24) are the most reliable to determine electron density (ED) with commercial single energy CT scanners. Along with the recent developments in dual energy CT (DECT) commercial scanners, several methods were published to determine ED and the effective atomic number (EAN) for polyenergetic beams without the need for CT calibration curves. This paper intends to show that with a rigorous definition of the EAN, the stoichiometric calibration method can be successfully adapted to DECT with significant accuracy improvements with respect to the literature without the need for spectrum measurements or empirical beam hardening corrections. Using a theoretical framework of ICRP human tissue compositions and the XCOM photon cross sections database, the revised stoichiometric calibration method yields Hounsfield unit (HU) predictions within less than ±1.3 HU of the theoretical HU calculated from XCOM data averaged over the spectra used (e.g., 80 kVp, 100 kVp, 140 kVp and 140/Sn kVp). A fit of mean excitation energy (I-value) data as a function of EAN is provided in order to determine the ion stopping power of human tissues from ED–EAN measurements. Analysis of the calibration phantom measurements with the Siemens SOMATOM Definition Flash dual source CT scanner shows that the present formalism yields mean absolute errors of (0.3 ± 0.4)% and (1.6 ± 2.0)% on ED and EAN, respectively. For ion therapy, the mean absolute errors for calibrated I-values and proton stopping powers (216 MeV) are (4.1 ± 2.7)% and (0.5 ± 0.4)%, respectively. In all clinical situations studied, the uncertainties in ion ranges in water for therapeutic energies are found to be less than 1.3 mm, 0.7 mm and 0.5 mm for protons, helium and carbon ions respectively, using a

  10. Calibration method for direct conversion receiver front-ends

    Directory of Open Access Journals (Sweden)

    R. Müller

    2008-05-01

    Full Text Available Technology induced process tolerances in analog circuits cause device characteristics different from specification. For direct conversion receiver front-ends a system level calibration method is presented. The malfunctions of the devices are compensated by tuning dominant circuit parameters. Thereto optimization techniques are applied which use measurement values and special evaluation functions.

  11. Liquid scintillation counting as a calibration method for PAEC monitors

    International Nuclear Information System (INIS)

    Measurements of potential alpha energy concentration (PAEC) of radon progeny are obligatory in Polish coal mines. Very important problem is a proper calibration of PAEC monitors for coal mining industry. It is very know fact, that is no possibility of producing of standard atmosphere of radon progeny. Therefore calibration is usually based on comparison of read-out of PAEC monitor with more counting of this filter immersed in a liquid scintillation counter (LSC) gives as a result an absolute method of PAEC measurements, because of very high efficiency for alpha and beta particles in liquid scintillator (almost 100%). (author). 30 refs, 2 figs

  12. Analysis of TRIGA reactor thermal power calibration method

    International Nuclear Information System (INIS)

    Analysis of thermal power method of the nuclear instrumentation of the TRIGA reactor in Ljubljana is described. Thermal power calibration was performed at different power levels and at different conditions. Different heat loss processes from the reactor pool to the surrounding are considered. It is shown that the use of proper calorimetric calibration procedure and the use of heat loss corrections improve the accuracy of the measurement. To correct the position of the control rods, perturbation factors are introduced. It is shown that the use of the perturbation factors enables power readings from nuclear instrumentation with accuracy better than without corrections.(author)

  13. A non-local model analysis of heat pulse propagation

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, T. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka (Japan); Itoh, S.I.; Yagi, M. [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics; Itoh, K. [National Inst. for Fusion Science, Nagoya (Japan); Stroth, U. [Max-Planck-Institute fuer Plasmaphysik, Garching (Germany)

    1998-08-01

    The anomalous transport in high temperature plasma has been studied for a long time, from the beginning of the fusion research. Since the electron channel in stellarators and tokamaks is clearly anomalous, it is of fundamental importance to investigate the electron heat diffusivity coefficient, {chi}{sub e} and to understand the physical mechanism. Recently, the experimental data for the transient transport of the heat pulse propagation in fusion plasma has been accumulated. An observation was reported on W7-AS which the heat flux changes faster than the change of the temperature profile, responding to the switching on off of the central heating power. The observation on the transient response has simulated the transport modeling, e.g., the critical marginality which implies the existence of a finite threshold in {nabla}T for the excitation of the turbulence, or the model in which the thermal conductivity is assumed to depend on the heating power. Extensive study is made by use of these models, and the critical marginally model seems to be insufficient to explain various transient transport. The rapid change of the plasma state and its hysteresis nature were successfully modeled by a heating-power-dependent model. The foundation of this model, however, is left for future work. The development of the transport modeling remains to be an urgent problem. In this paper, we investigate the role of the non-locality of the plasma transport in the study of the heat pulse propagation. For this purpose, a model equation is proposed, in which the non-local effect is taken into account in the heat flux. The properties of this model are investigated by performing a transport simulation. The organization of this paper is as follows: In Sec. II, the model equation is proposed and the properties of the model are explained. Using the model equation, the switching on off experiment is simulated in Sec. III. Summary and discussion are given in Sec. IV. (author)

  14. Histogram-Based Calibration Method for Pipeline ADCs.

    Directory of Open Access Journals (Sweden)

    Hyeonuk Son

    Full Text Available Measurement and calibration of an analog-to-digital converter (ADC using a histogram-based method requires a large volume of data and a long test duration, especially for a high resolution ADC. A fast and accurate calibration method for pipelined ADCs is proposed in this research. The proposed calibration method composes histograms through the outputs of each stage and calculates error sources. The digitized outputs of a stage are influenced directly by the operation of the prior stage, so the results of the histogram provide the information of errors in the prior stage. The composed histograms reduce the required samples and thus calibration time being implemented by simple modules. For 14-bit resolution pipelined ADC, the measured maximum integral non-linearity (INL is improved from 6.78 to 0.52 LSB, and the spurious-free dynamic range (SFDR and signal-to-noise-and-distortion ratio (SNDR are improved from 67.0 to 106.2dB and from 65.6 to 84.8dB, respectively.

  15. Histogram-Based Calibration Method for Pipeline ADCs.

    Science.gov (United States)

    Son, Hyeonuk; Jang, Jaewon; Kim, Heetae; Kang, Sungho

    2015-01-01

    Measurement and calibration of an analog-to-digital converter (ADC) using a histogram-based method requires a large volume of data and a long test duration, especially for a high resolution ADC. A fast and accurate calibration method for pipelined ADCs is proposed in this research. The proposed calibration method composes histograms through the outputs of each stage and calculates error sources. The digitized outputs of a stage are influenced directly by the operation of the prior stage, so the results of the histogram provide the information of errors in the prior stage. The composed histograms reduce the required samples and thus calibration time being implemented by simple modules. For 14-bit resolution pipelined ADC, the measured maximum integral non-linearity (INL) is improved from 6.78 to 0.52 LSB, and the spurious-free dynamic range (SFDR) and signal-to-noise-and-distortion ratio (SNDR) are improved from 67.0 to 106.2dB and from 65.6 to 84.8dB, respectively. PMID:26070196

  16. An MLC calibration method using a detector array

    Energy Technology Data Exchange (ETDEWEB)

    Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray [Department of Nuclear and Radiological Engineering, University of Florida, 202 Nuclear Science Building, Gainesville, Florida 32611-8300 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States) and Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States); Sun Nuclear Corporation, 425-A Pineda Court, Melbourne, Florida 32940 (United States); Department of Radiation Oncology, Tulane University, 1415 Tulane Ave, HC65, New Orleans, Louisiana 70112 (United States); Department of Radiation Oncology, Health Science Center, University of Florida, P.O. Box 100385, Gainesville, Florida 32610-0385 (United States)

    2009-10-15

    Purpose: The authors have developed a quantitative calibration method for a multileaf collimator (MLC) which measures individual leaf positions relative to the MLC backup jaw on an Elekta Synergy linear accelerator. Methods: The method utilizes a commercially available two-axis detector array (Profiler 2; Sun Nuclear Corporation, Melbourne, FL). To calibrate the MLC bank, its backup jaw is positioned at the central axis and the opposing jaw is retracted to create a half-beam configuration. The position of the backup jaws field edge is then measured with the array to obtain what is termed the radiation defined reference line. The positions of the individual leaf ends relative to this reference line are then inferred by the detector response in the leaf end penumbra. Iteratively adjusting and remeasuring the leaf end positions to within specifications completes the calibration. Using the backup jaw as a reference for the leaf end positions is based on three assumptions: (1) The leading edge of an MLC leaf bank is parallel to its backup jaw's leading edge, (2) the backup jaw position is reproducible, and (3) the measured radiation field edge created by each leaf end is representative of that leaf's position. Data from an electronic portal imaging device (EPID) were used in a similar analysis to check the results obtained with the array. Results: The relative leaf end positions measured with the array differed from those measured with the EPID by an average of 0.11 {+-}0.09 mm per leaf. The maximum leaf positional change measured with the Profiler 2 over a 3 month period was 0.51 mm. A leaf positional accuracy of {+-}0.4 mm is easily attainable through the iterative calibration process. The method requires an average of 40 min to measure both leaf banks. Conclusions: This work demonstrates that the Profiler 2 is an effective tool for efficient and quantitative MLC quality assurance and calibration.

  17. A WEIGHTED ITERATIVE METHOD FOR ROBUST SELF-CALIBRATION

    Institute of Scientific and Technical Information of China (English)

    Liu Shigang; Wu Chengke; Tang Li; Jia Jing

    2006-01-01

    A robust self-calibration method is presented, which can efficiently discard the outliers based on a Weighted Iteration Method (WIM). The method is an iterative process in which the projective reconstruction is obtained based on the weights of all the points, whereas the weights are defined in inverse proportion to the reciprocal of the re-projective errors. The weights of outliers trend to zero after several iterations, and the accurate projective reconstruction is determined. The location of the absolute conic and the camera intrinsic parameters are obtained after the projective reconstruction. The theory and experiments with both simulate and real data demonstrate that the proposed method is very efficient and robust.

  18. Optimised Calibration Method for Six-Port Junction

    Institute of Scientific and Technical Information of China (English)

    XIONG Xiang-zheng; LIAO Cheng; XIAO Hua-qing

    2008-01-01

    A dual-tone technique is used to produce multi-samples in optimising calibration of six-port junction. More accurate results are achieved by using the least-square method and excluding those samples which may cause bigger errors. A 0.80 1.10 GHz microwave integrated circuit (MIC) six-port reflectometer is constructed. Nine test samples are used in the measurement. With Engens calibration procedure, the difference between the HP8510 and the six-port reflectrometer is in the order of 0.20 dB/1.5° for most cases, above 0.50 dB/5.0° at boundary frequency . With the optimised method, the difference is less than 0.10 dB/1.0° for most cases, and the biggest error is 0.42 dB/2.1° for boundary frequencies.

  19. Spectrometric methods used in the calibration of radiodiagnostic measuring instruments

    Energy Technology Data Exchange (ETDEWEB)

    De Vries, W. [Rijksuniversiteit Utrecht (Netherlands)

    1995-12-01

    Recently a set of parameters for checking the quality of radiation for use in diagnostic radiology was established at the calibration facility of Nederlands Meetinstituut (NMI). The establishment of the radiation quality required re-evaluation of the correction factors for the primary air-kerma standards. Free-air ionisation chambers require several correction factors to measure air-kerma according to its definition. These correction factors were calculated for the NMi free-air chamber by Monte Carlo simulations for monoenergetic photons in the energy range from 10 keV to 320 keV. The actual correction factors follow from weighting these mono-energetic correction factors with the air-kerma spectrum of the photon beam. This paper describes the determination of the photon spectra of the X-ray qualities used for the calibration of dosimetric instruments used in radiodiagnostics. The detector used for these measurements is a planar HPGe-detector, placed in the direct beam of the X-ray machine. To convert the measured pulse height spectrum to the actual photon spectrum corrections must be made for fluorescent photon escape, single and multiple compton scattering inside the detector, and detector efficiency. From the calculated photon spectra a number of parameters of the X-ray beam can be calculated. The calculated first and second half value layer in aluminum and copper are compared with the measured values of these parameters to validate the method of spectrum reconstruction. Moreover the spectrum measurements offer the possibility to calibrate the X-ray generator in terms of maximum high voltage. The maximum photon energy in the spectrum is used as a standard for calibration of kVp-meters.

  20. The cryogenic balance design and balance calibration methods

    Science.gov (United States)

    Ewald, B.; Polanski, L.; Graewe, E.

    1992-07-01

    The current status of a program aimed at the development of a cryogenic balance for the European Transonic Wind Tunnel is reviewed. In particular, attention is given to the cryogenic balance design philosophy, mechanical balance design, reliability and accuracy, cryogenic balance calibration concept, and the concept of an automatic calibration machine. It is shown that the use of the automatic calibration machine will improve the accuracy of calibration while reducing the man power and time required for balance calibration.

  1. Evaluating the potential of a novel dual heat-pulse sensor to measure volumetric water use in grapevines under a range of flow conditions

    Science.gov (United States)

    The aim of this study was to validate dual sap flow sensors that combine two heat pulse techniques to measure volumetric water use over the full range of sap flows found in grapevines. The heat ratio method (HRM), which works well at measuring low and reverse flows, was combined with the compensati...

  2. Various methods and developments for calibrating seismological sensors at EOST

    Science.gov (United States)

    JUND, H.; Bès de Berc, M.; Thore, J.

    2013-12-01

    Calibrating seismic sensors is crucial for knowing the quality of the sensor and generating precise dataless files. We present here three calibration methods that we have developed for the short period and broad band sensors included in the temporary and permanent seismic networks in France. First, in the case of a short-period sensor with no electronics and calibration coil, we inject a sine wave signal into the signal coil. After locking the sensor mass, we first connect a voltage generator of signal waves and a series resistor to the coil. Then, a sinusoidal signal is sent to the sensor signal coil output. Both the voltage at the terminal of the resistor, which gives an image of the intensity entering the signal coil, and the voltage at the terminal of the signal coil are measured. The frequency of the generator then varies in order to find a phase shift between both signals of π/2. The output frequency of the generator corresponds to the image of the natural frequency of the sensor. Second, in the case of all types of sensors provided with a calibration coil, we inject different signals into the calibration coil. We usually apply two signals: a step signal and a sweep (or wobble) signal. A step signal into the calibration coil is equivalent to a Dirac excitation in derived acceleration. The response to this Dirac gives the transfer function of the signal coil, derived two times and without absolute gain. We developed a field-module allowing us to always apply the same excitation to various models of seismometers, in order to compare the results from several instruments previously installed on field. A wobble signal is a signal whose frequency varies. By varying the frequency of the input signal around the sensor's natural frequency, we obtain an immediate response of the sensor in acceleration. This method is particularly suitable in order to avoid any disturbances which may modify the signal of a permanent station. Finally, for the determination of absolute

  3. A quick telemanipulator calibration and repeatability method with applications

    Energy Technology Data Exchange (ETDEWEB)

    Jansen, J.F.; Haley, D.C. [Oak Ridge National Lab., TN (United States). Robotics & Process Systems Div.

    1994-09-01

    This paper will present a methodology that was used to calibrate and measure the repeatability of two telemanipulators at Oak Ridge National Laboratory. The global accuracy of the method was 0.05 in. ({approx_equal} 1.3 mm), and the orientation accuracy was approximately 6 min ({approx_equal} 0.002 rads). For most teleoperator systems, these accuracies are more than adequate because of the construction of the mechanism and sensor capabilities (e.g., typically 12 bits of resolution). Although industrial robots require accuracies of about 0.05 mm or better, telemanipulators do not.

  4. A Bionic Polarization Navigation Sensor and Its Calibration Method.

    Science.gov (United States)

    Zhao, Huijie; Xu, Wujian

    2016-01-01

    The polarization patterns of skylight which arise due to the scattering of sunlight in the atmosphere can be used by many insects for deriving compass information. Inspired by insects' polarized light compass, scientists have developed a new kind of navigation method. One of the key techniques in this method is the polarimetric sensor which is used to acquire direction information from skylight. In this paper, a polarization navigation sensor is proposed which imitates the working principles of the polarization vision systems of insects. We introduce the optical design and mathematical model of the sensor. In addition, a calibration method based on variable substitution and non-linear curve fitting is proposed. The results obtained from the outdoor experiments provide support for the feasibility and precision of the sensor. The sensor's signal processing can be well described using our mathematical model. A relatively high degree of accuracy in polarization measurement can be obtained without any error compensation.

  5. A Bionic Polarization Navigation Sensor and Its Calibration Method.

    Science.gov (United States)

    Zhao, Huijie; Xu, Wujian

    2016-01-01

    The polarization patterns of skylight which arise due to the scattering of sunlight in the atmosphere can be used by many insects for deriving compass information. Inspired by insects' polarized light compass, scientists have developed a new kind of navigation method. One of the key techniques in this method is the polarimetric sensor which is used to acquire direction information from skylight. In this paper, a polarization navigation sensor is proposed which imitates the working principles of the polarization vision systems of insects. We introduce the optical design and mathematical model of the sensor. In addition, a calibration method based on variable substitution and non-linear curve fitting is proposed. The results obtained from the outdoor experiments provide support for the feasibility and precision of the sensor. The sensor's signal processing can be well described using our mathematical model. A relatively high degree of accuracy in polarization measurement can be obtained without any error compensation. PMID:27527171

  6. A Bionic Polarization Navigation Sensor and Its Calibration Method

    Science.gov (United States)

    Zhao, Huijie; Xu, Wujian

    2016-01-01

    The polarization patterns of skylight which arise due to the scattering of sunlight in the atmosphere can be used by many insects for deriving compass information. Inspired by insects’ polarized light compass, scientists have developed a new kind of navigation method. One of the key techniques in this method is the polarimetric sensor which is used to acquire direction information from skylight. In this paper, a polarization navigation sensor is proposed which imitates the working principles of the polarization vision systems of insects. We introduce the optical design and mathematical model of the sensor. In addition, a calibration method based on variable substitution and non-linear curve fitting is proposed. The results obtained from the outdoor experiments provide support for the feasibility and precision of the sensor. The sensor’s signal processing can be well described using our mathematical model. A relatively high degree of accuracy in polarization measurement can be obtained without any error compensation. PMID:27527171

  7. Adaptive calibration method with on-line growing complexity

    OpenAIRE

    Šika Z.; Skopec T.

    2011-01-01

    This paper describes a modified variant of a kinematical calibration algorithm. In the beginning, a brief review of the calibration algorithm and its simple modification are described. As the described calibration modification uses some ideas used by the Lolimot algorithm, the algorithm is described and explained. Main topic of this paper is a description of a synthesis of the Lolimot-based calibration that leads to an adaptive algorithm with an on-line growing complexity. The paper contains ...

  8. Method for Ground-to-Space Laser Calibration System

    Science.gov (United States)

    Lukashin, Constantine (Inventor); Wielicki, Bruce A. (Inventor)

    2014-01-01

    The present invention comprises an approach for calibrating the sensitivity to polarization, optics degradation, spectral and stray light response functions of instruments on orbit. The concept is based on using an accurate ground-based laser system, Ground-to-Space Laser Calibration (GSLC), transmitting laser light to instrument on orbit during nighttime substantially clear-sky conditions. To minimize atmospheric contribution to the calibration uncertainty the calibration cycles should be performed in short time intervals, and all required measurements are designed to be relative. The calibration cycles involve ground operations with laser beam polarization and wavelength changes.

  9. Calibration of high resolution digital camera based on different photogrammetric methods

    International Nuclear Information System (INIS)

    This paper presents method of calibrating high-resolution digital camera based on different configuration which comprised of stereo and convergent. Both methods are performed in the laboratory and in the field calibration. Laboratory calibration is based on a 3D test field where a calibration plate of dimension 0.4 m × 0.4 m with grid of targets at different height is used. For field calibration, it uses the same concept of 3D test field which comprised of 81 target points located on a flat ground and the dimension is 9 m × 9 m. In this study, a non-metric high resolution digital camera called Canon Power Shot SX230 HS was calibrated in the laboratory and in the field using different configuration for data acquisition. The aim of the calibration is to investigate the behavior of the internal digital camera whether all the digital camera parameters such as focal length, principal point and other parameters remain the same or vice-versa. In the laboratory, a scale bar is placed in the test field for scaling the image and approximate coordinates were used for calibration process. Similar method is utilized in the field calibration. For both test fields, the digital images were acquired within short period using stereo and convergent configuration. For field calibration, aerial digital images were acquired using unmanned aerial vehicle (UAV) system. All the images were processed using photogrammetric calibration software. Different calibration results were obtained for both laboratory and field calibrations. The accuracy of the results is evaluated based on standard deviation. In general, for photogrammetric applications and other applications the digital camera must be calibrated for obtaining accurate measurement or results. The best method of calibration depends on the type of applications. Finally, for most applications the digital camera is calibrated on site, hence, field calibration is the best method of calibration and could be employed for obtaining accurate

  10. A Method Suitable for Vicarious Calibration of a UAV HyperspectralRemote Sensor

    OpenAIRE

    Zhang, Hao; Li, Haiwei; Yang, Benyong; Chen, Zhengchao

    2015-01-01

    A sensor aboard an unmanned aerial vehicle (UAV) is vulnerable to vibration and natural conditions such as erratic winds. Considering the difference between laboratory and vicarious environments of calibration, a vicarious calibration is closer to the real environment and is a complement to laboratory calibrations for remote sensors. The existing vicarious calibration of UAVs only uses a reflectance-based method, rather than irradiance-based method. Therefore, the error caused by aerosol type...

  11. On-site calibration method for outdoor binocular stereo vision sensors

    Science.gov (United States)

    Liu, Zhen; Yin, Yang; Wu, Qun; Li, Xiaojing; Zhang, Guangjun

    2016-11-01

    Using existing calibration methods for binocular stereo vision sensors (BSVS), it is very difficult to extract target characteristic points in outdoor environments under complex light conditions. To solve the problem, an online calibration method for BSVS based a double parallel cylindrical target and a line laser projector is proposed in this paper. The intrinsic parameters of two cameras are calibrated offline. Laser strips on the double parallel cylindrical target are mediated to calibrate the configuration parameters of BSVS. The proposed method only requires images of laser strips on the target and is suitable for the calibration of BSVS in outdoor environments. The effectiveness of the proposed method is validated through physical experiments.

  12. Improved method of SSC strain gauge calibration at cryogenic temperatures

    International Nuclear Information System (INIS)

    The development of an improved strain gauge calibration station for the SSC dipole magnets will have several advantages. The new design will use significantly less helium, provide for a much higher productivity, and will generate completely automated calibration reports. This will be accomplished by having a finer control over the press pressures, prechilling of the transducers, changing the calibrated transducers for uncalibrated transducers without frosting or warming the press, and the possibility of recovering the spent helium. Five main components make up the system: (1) Test Vessel - non-pressurized cryogenic vessel where the strain gauges are calibrated; (2) Precool Vessel - non-pressurized cryogenic vessel where six strain gauge fixtures are placed for precooling; (3) Fixture - used to hold the two strain gauges that are being calibrated; (4) Hydraulics - dual stage air-over-oil system controlled by an electronic-pneumatic valve; and (5) Computer - controls the electronic-pneumatic valve and records all the readings to calibrate the strain gauges

  13. Simple method for calibrating omnidirectional stereo with multiple cameras

    Science.gov (United States)

    Ha, Jong-Eun; Choi, I.-Sak

    2011-04-01

    Cameras can give useful information for the autonomous navigation of a mobile robot. Typically, one or two cameras are used for this task. Recently, an omnidirectional stereo vision system that can cover the whole surrounding environment of a mobile robot is adopted. They usually adopt a mirror that cannot offer uniform spatial resolution. In this paper, we deal with an omnidirectional stereo system which consists of eight cameras where each two vertical cameras constitute one stereo system. Camera calibration is the first necessary step to obtain 3D information. Calibration using a planar pattern requires many images acquired under different poses so it is a tedious step to calibrate all eight cameras. In this paper, we present a simple calibration procedure using a cubic-type calibration structure that surrounds the omnidirectional stereo system. We can calibrate all the cameras on an omnidirectional stereo system in just one shot.

  14. Heat Fluxes and Evaporation Measurements by Multi-Function Heat Pulse Probe: a Laboratory Experiment

    Science.gov (United States)

    Sharma, V.; Ciocca, F.; Hopmans, J. W.; Kamai, T.; Lunati, I.; Parlange, M. B.

    2012-04-01

    Multi Functional Heat Pulse Probes (MFHPP) are multi-needles probes developed in the last years able to measure temperature, thermal properties such as thermal diffusivity and volumetric heat capacity, from which soil moisture is directly retrieved, and electric conductivity (through a Wenner array). They allow the simultaneous measurement of coupled heat, water and solute transport in porous media, then. The use of only one instrument to estimate different quantities in the same volume and almost at the same time significantly reduces the need to interpolate different measurement types in space and time, increasing the ability to study the interdependencies characterizing the coupled transports, especially of water and heat, and water and solute. A three steps laboratory experiment is realized at EPFL to investigate the effectiveness and reliability of the MFHPP responses in a loamy soil from Conthey, Switzerland. In the first step specific calibration curves of volumetric heat capacity and thermal conductivity as function of known volumetric water content are obtained placing the MFHPP in small samplers filled with the soil homogeneously packed at different saturation degrees. The results are compared with literature values. In the second stage the ability of the MFHPP to measure heat fluxes is tested within a homemade thermally insulated calibration box and results are matched with those by two self-calibrating Heatflux plates (from Huxseflux), placed in the same box. In the last step the MFHPP are used to estimate the cumulative subsurface evaporation inside a small column (30 centimeters height per 8 centimeters inner diameter), placed on a scale, filled with the same loamy soil (homogeneously packed and then saturated) and equipped with a vertical array of four MFHPP inserted close to the surface. The subsurface evaporation is calculated from the difference between the net sensible heat and the net heat storage in the volume scanned by the probes, and the

  15. Adaptive calibration method with on-line growing complexity

    Directory of Open Access Journals (Sweden)

    Šika Z.

    2011-12-01

    Full Text Available This paper describes a modified variant of a kinematical calibration algorithm. In the beginning, a brief review of the calibration algorithm and its simple modification are described. As the described calibration modification uses some ideas used by the Lolimot algorithm, the algorithm is described and explained. Main topic of this paper is a description of a synthesis of the Lolimot-based calibration that leads to an adaptive algorithm with an on-line growing complexity. The paper contains a comparison of simple examples results and a discussion. A note about future research topics is also included.

  16. Sapflow+: a four-needle heat-pulse sap flow sensor enabling nonempirical sap flux density and water content measurements.

    Science.gov (United States)

    Vandegehuchte, Maurits W; Steppe, Kathy

    2012-10-01

    • To our knowledge, to date, no nonempirical method exists to measure reverse, low or high sap flux density. Moreover, existing sap flow methods require destructive wood core measurements to determine sapwood water content, necessary to convert heat velocity to sap flux density, not only damaging the tree, but also neglecting seasonal variability in sapwood water content. • Here, we present a nonempirical heat-pulse-based method and coupled sensor which measure temperature changes around a linear heater in both axial and tangential directions after application of a heat pulse. By fitting the correct heat conduction-convection equation to the measured temperature profiles, the heat velocity and water content of the sapwood can be determined. • An identifiability analysis and validation tests on artificial and real stem segments of European beech (Fagus sylvatica L.) confirm the applicability of the method, leading to accurate determinations of heat velocity, water content and hence sap flux density. • The proposed method enables sap flux density measurements to be made across the entire natural occurring sap flux density range of woody plants. Moreover, the water content during low flows can be determined accurately, enabling a correct conversion from heat velocity to sap flux density without destructive core measurements.

  17. Calibration Methods for Air Coupled Antennas - COST Action TU1208

    Science.gov (United States)

    Marecos, Vânia; Solla, Mercedes; Fontul, Simona; Pajewski, Lara

    2016-04-01

    This work focuses on the comparison of different methods for calibrating air coupled antennas: Coring, Surface Reflection Method (SRM) and Common Mid-Point (CMP) through the analysis of GPR data collected in a test site with different pavement solutions. Research activities have been carried out during a Short Term Scientific Mission (STSM) funded by the COST (European Cooperation in Science and Technology) Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar" in December 2015. The use of GPR in transport infrastructures represents one of the most significant advances for obtaining continuous data along the road, with the advantage of operation at traffic speed and being a non-destructive technique. Its main application has been the evaluation of layer thickness. For the determination of layer thickness, it is necessary to know the velocity of the signal, which depends on the dielectric constant of the material, and the two-way travel time of the reflected signal that is recorded by the GPR system. The calculation of the dielectric value of the materials can be done using different approaches such as: using fixed values based on experience, laboratory determination of dielectric values, applying the SRM, performing back calculation from ground truth references such as cores and test pits, or using the CMP method. The problem with using ground truth is that it is time consuming, labour intensive and intrusive to traffic, in addition, a drill core is not necessarily representative of the whole surveyed area. Regarding the surface reflection technique, one of the problems is that it only measures the dielectric value from the layer surface and not from the whole layer. Recent works already started to address some of these challenges proposing new approaches for GPR layer thickness measurements using multiple antennas to calculate the average dielectric value of the asphalt layer, taking advantage of significant hardware improvements in GPR

  18. Calibrating optical bubble size by the displaced-mass method.

    NARCIS (Netherlands)

    Leifer, I.; Leeuw, G. de; Kunz, G.; Cohen, L.H.

    2003-01-01

    Bubble sizing by optical means is very common, but requires calibration by non-optical means. This is particularly important since apparent bubble size increases with decreasing threshold intensity. A calibration experiment was conducted comparing the displaced water mass from captured bubbles with

  19. A universal method for camera calibration in UITS scenes

    Institute of Scientific and Technical Information of China (English)

    Zhaoxue Chen; Pengfei Shi

    2005-01-01

    @@ A universal approach to camera calibration based on features of some representative lines on traffic ground is presented. It uses only a set of three parallel edges with known intervals and one of their intersected lines with known slope to gain the focal length and orientation parameters of a camera. A set of equations that computes related camera parameters has been derived from geometric properties of the calibration pattern. With accurate analytical implementation, precision of the approach is only decided by accuracy of the calibration target selecting. Final experimental results have showed its validity by a snapshot from real automatic visual traffic surveillance (AVTS) scenes.

  20. One step geometrical calibration method for optical coherence tomography

    International Nuclear Information System (INIS)

    We present a novel one-step calibration methodology for geometrical distortion correction for optical coherence tomography (OCT). A calibration standard especially designed for OCT is introduced, which consists of an array of inverse pyramidal structures. The use of multiple landmarks situated on four different height levels on the pyramids allow performing a 3D geometrical calibration. The calibration procedure itself is based on a parametric model of the OCT beam propagation. It is validated by experimental results and enables the reduction of systematic errors by more than one order of magnitude. In future, our results can improve OCT image reconstruction and interpretation for medical applications such as real time monitoring of surgery. (paper)

  1. Two-Step Camera Calibration Method Developed for Micro UAV'S

    Science.gov (United States)

    Gašparović, M.; Gajski, D.

    2016-06-01

    The development of unmanned aerial vehicles (UAVs) and continuous price reduction of unmanned systems attracted us to this research. Professional measuring systems are dozens of times more expensive and often heavier than "amateur", non-metric UAVs. For this reason, we tested the DJI Phantom 2 Vision Plus UAV. Phantom's smaller mass and velocity can develop less kinetic energy in relation to the professional measurement platforms, which makes it potentially less dangerous for use in populated areas. In this research, we wanted to investigate the ability of such non-metric UAV and find the procedures under which this kind of UAV may be used for the photogrammetric survey. It is important to emphasize that UAV is equipped with an ultra wide-angle camera with 14MP sensor. Calibration of such cameras is a complex process. In the research, a new two-step process is presented and developed, and the results are compared with standard one-step camera calibration procedure. Two-step process involves initially removed distortion on all images, and then uses these images in the phototriangulation with self-calibration. The paper presents statistical indicators which proved that the proposed two-step process is better and more accurate procedure for calibrating those types of cameras than standard one-step calibration. Also, we suggest two-step calibration process as the standard for ultra-wideangle cameras for unmanned aircraft.

  2. Optical geometry calibration method for free-form digital tomosynthesis

    Science.gov (United States)

    Chtcheprov, Pavel; Hartman, Allison; Shan, Jing; Lee, Yueh Z.; Zhou, Otto; Lu, Jianping

    2016-03-01

    Digital tomosynthesis is a type of limited angle tomography that allows 3D information to be reconstructed from a set of x-ray projection images taken at various angles using an x-ray tube, a mechanical arm to rotate the tube about the object, and a digital detector. Tomosynthesis reconstruction requires the precise location of the detector with respect to each x-ray source, forcing all current clinical tomosynthesis systems to use a physically coupled source and detector so the geometry is always known and is always the same. This limits the imaging geometries and its large size is impractical for mobile or field operations. To counter this, we have developed a free form tomosynthesis with a decoupled, free-moving source and detector that uses a novel optical method for accurate and real-time geometry calibration to allow for manual, hand-held tomosynthesis and even CT imaging. We accomplish this by using a camera, attached to the source, to track the motion of the source relative to the detector. Attached to the detector is an optical pattern and the image captured by the camera is then used to determine the relative camera/pattern position and orientation by analyzing the pattern distortion and calculating the source positions for each projection, necessary for 3D reconstruction. This allows for portable imaging in the field and also as an inexpensive upgrade to existing 2D systems, such as in developing countries, to provide 3D image data. Here we report the first feasibility demonstrations of free form digital tomosynthesis systems using the method.

  3. Improvements on the directional characteristics of a calibration sound source using the Boundary Element Method

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Barrera Figueroa, Salvador; Juhl, Peter Møller

    2008-01-01

    The project Euromet-792 aims to investigate and improve methods for secondary free-field calibration of microphones. In this framework, the comparison method is being studied at DFM in relation to the more usual substitution method of microphone calibration. The design of the sound source is of p...

  4. Comparison of pencil-type ionization chamber calibration results and methods between dosimetry laboratories.

    Science.gov (United States)

    Hourdakis, Costas J; Büermann, Ludwig; Ciraj-Bjelac, Olivera; Csete, Istvan; Delis, Harry; Gomola, Igor; Persson, Linda; Novak, Leos; Petkov, Ivailo; Toroi, Paula

    2016-01-01

    A comparison of calibration results and procedures in terms of air kerma length product, PKL, and air kerma, K, was conducted between eight dosimetry laboratories. A pencil-type ionization chamber (IC), generally used for computed tomography dose measurements, was calibrated according to three calibration methods, while its residual signal and other characteristics (sensitivity profile, active length) were assessed. The results showed that the "partial irradiation method" is the preferred method for the pencil-type IC calibration in terms of PKL and it could be applied by the calibration laboratories successfully. Most of the participating laboratories achieved high level of agreement (>99%) for both dosimetry quantities (PKL and K). Estimated relative standard uncertainties of comparison results vary among laboratories from 0.34% to 2.32% depending on the quantity, beam quality and calibration method applied. Detailed analysis of the assigned uncertainties have been presented and discussed.

  5. A direct micropipette-based calibration method for atomic force microscope cantilevers

    OpenAIRE

    Liu, Baoyu; Yu, Yan; Yao, Da-Kang; Shao, Jin-Yu

    2009-01-01

    In this report, we describe a direct method for calibrating atomic force microscope (AFM) cantilevers with the micropipette aspiration technique (MAT). A closely fitting polystyrene bead inside a micropipette is driven by precisely controlled hydrostatic pressures to apply known loads on the sharp tip of AFM cantilevers, thus providing a calibration at the most functionally relevant position. The new method is capable of calibrating cantilevers with spring constants ranging from 0.01 to hundr...

  6. STUDY ON A PRECISE ON-SPOT CALIBRATION METHOD FOR DISTRIBUTED STEREO REFERENCE POSITION-SETTING

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A high precision method used for on-spot calibration of distributed stereo reference position Setting is pre-sented. The high measuring accuracy in stereo reference calibration is derived from using a high precision water level in-strument and an accurate height vernier caliper. It settles the problem of reference calibration effectively and accurately,without using large coordinate measuring machines (CMM). It is more adaptable and precise than traditional calibrationmethods applying theodolites or autocollimators. The error sources of this method are analyzed in detail and severalmethods are developed to eliminate the calibration error. An optimizing swallowtail-like anchor target is developed. Ex-periments show that the calibration accuracy can be limited within 0.06 mm in the range of 3~5 m and 0.03 mm withoptimizing anchor target. This method can be widely used in on-spot calibration.

  7. A New Method for Calibrating the Time Delay of a Piezoelectric Probe

    DEFF Research Database (Denmark)

    Hansen, Bengt Hurup

    1974-01-01

    A simple method for calibrating the time delay of a piezoelectric probe of the type often used in plasma physics is described.......A simple method for calibrating the time delay of a piezoelectric probe of the type often used in plasma physics is described....

  8. Heat pulse propagation studies around magnetic islands induced by the Dynamic Ergodic Divertor in TEXTOR

    NARCIS (Netherlands)

    Spakman, G. W.; Hogeweij, G. M. D.; Jaspers, R. J. E.; Schüller, F. C.; Westerhof, E.; Boom, J. E.; Classen, I.G.J.; Delabie, E.; Domier, C.; Donne, A. J. H.; Kantor, M. Y.; Kramer-Flecken, A.; Liang, Y.; N C Luhmann Jr.,; Park, H. K.; van de Pol, M.J.; Schmitz, O.; Oosterbeek, J. W.

    2008-01-01

    Since the efficiency of the tearing mode suppression by heating depends on the electron heat diffusivity it is important to know if the electron heat transport coefficients inside the island are reduced compared with the ambient plasma. With that aim, modulated ECRH has been employed for heat pulse

  9. Theories and heat pulse experiments of non-Fourier heat conduction

    Directory of Open Access Journals (Sweden)

    Ván Péter

    2016-06-01

    Full Text Available The experimental basis and theoretical background of non-Fourier heat conduction is shortly reviewed from the point of view of non-equilibrium thermodynamics. The performance of different theories is compared in case of heat pulse experiments.

  10. An innovative method to calibrate a spinner anemometer without the use of yaw position sensor

    DEFF Research Database (Denmark)

    Demurtas, Giorgio; Janssen, Nick Gerardus Cornelis

    2016-01-01

    A spinner anemometer can be used to measure the yaw misalignment and flow inclination experienced by a wind turbine. Previous calibration methods used to calibrate a spinner anemometer for flow angle measurements were based on measurements of a spinner anemometer with default settings (arbitrary...... values, generally k1,d  =  1 and k2,d  =  1) and a reference yaw misalignment signal measured with a yaw position sensor. The yaw position sensor is normally present in wind turbines for control purposes; however, such a signal is not always available for a spinner anemometer calibration. Therefore......, an additional yaw position sensor was installed prior to the spinner anemometer calibration. An innovative method to calibrate the spinner anemometer without a yaw positions sensor was then developed. It was noted that a non-calibrated spinner anemometer that overestimates (underestimates) the inflow angle...

  11. Asymptotically Optimal Algorithm for Short-Term Trading Based on the Method of Calibration

    CERN Document Server

    V'yugin, Vladimir

    2012-01-01

    A trading strategy based on a natural learning process, which asymptotically outperforms any trading strategy from RKHS (Reproduced Kernel Hilbert Space), is presented. In this process, the trader rationally chooses his gambles using predictions made by a randomized well calibrated algorithm. Our strategy is based on Dawid's notion of calibration with more general changing checking rules and on some modification of Kakade and Foster's randomized algorithm for computing calibrated forecasts. We use also Vovk's method of defensive forecasting in RKHS.

  12. Standard Test Method for Calibration of Non-Concentrator Photovoltaic Secondary Reference Cells

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method covers calibration and characterization of secondary terrestrial photovoltaic reference cells to a desired reference spectral irradiance distribution. The recommended physical requirements for these reference cells are described in Specification E1040. Reference cells are principally used in the determination of the electrical performance of a photovoltaic device. 1.2 Secondary reference cells are calibrated indoors using simulated sunlight or outdoors in natural sunlight by reference to a primary reference cell previously calibrated to the same desired reference spectral irradiance distribution. 1.3 Secondary reference cells calibrated according to this test method will have the same radiometric traceability as the of the primary reference cell used for the calibration. Therefore, if the primary reference cell is traceable to the World Radiometric Reference (WRR, see Test Method E816), the resulting secondary reference cell will also be traceable to the WRR. 1.4 This test method appli...

  13. Development and application of a heat pulse sensor for in-situ measurement of hyporheic flow

    Science.gov (United States)

    Angermann, L.; Lewandowski, J.; Fleckenstein, J. H.; Krause, S.; Nuetzmann, G.

    2011-12-01

    The riverine system represents a continuum of surface water (SW), shallow groundwater (GW) and the interconnecting hyporheic zone (HZ). Within this conceptual model, the HZ fulfills important ecological and biogeochemical functions caused by the high specific surface of sediment, the abundance of organic matter and steep and dynamic gradients in temperature, redox potential and oxygen content. These milieu conditions are controlled by the type and intensity of GW-SW interaction like GW-discharge, SW infiltration, alternating up- and downwelling or dominantly horizontal flow. Depending on flow regimes, the HZ either acts as mixing layer or transit zone with the respective end-member mixing ratios and residence times. Hyporheic exchange fluxes (HEF) at different scales potentially interact, superimpose and prevail each other. It is therefore crucial to understand the complex interactions of SW-GW exchange fluxes from patterns at stream reach scale down to shallow HEF in the top 20cm streambed. Field measurements of GW-SW exchange are technically challenging, especially at the decimeter scale and below. This study presents a novel heat pulse sensor (HPS) which was developed for measuring shallow HEF. The method is based on a short heat pulse which is emitted into the sediment in the depth of 5 to 10cm. Breakthrough curves of the heat propagating through the sediment are recorded by a 3D sensor array around the heat source and analyzed with an analytical solution of the advective-conductive heat transport equation in a cylindrical coordinate system. Theoretical breakthrough curves are calculated for every sensor and flow velocity and the position of the longitudinal axis, which is defined parallel to flow, are fitted. After validation in controlled lab environment, the method was applied in the streambed of 3 subsections of a 250m stream reach with heterogeneous patterns of mainly sandy sediments, representing characteristic streambed conditions of a meandering lowland

  14. Calibration systems and methods for the ANTARES neutrino telescope

    CERN Document Server

    Fehr, Felix

    2007-01-01

    The ANTARES neutrino telescope is currently being constructed in the Mediterranean Sea. The complete detector will consist of 12 strings, supplemented by an additional instrumentation line. Nine strings are at present deployed of which five are already connected to the shore and operating. Each string is equipped with 75 Optical Modules (OMs) housing the photomultipliers to detect the Cherenkov light induced by the charged particles produced in neutrino reactions. An accurate measurement of the Cherenkov photon arrival times as well as the positions and orientations of the OMs is required for a precise reconstruction of the direction of the detected neutrinos. For this purpose the ANTARES detector is provided with several system s to facilitate the calibration of the detector. The time calibration is performed using light pulses emitted from LED and laser devices. The positioning is done via acoustic triangulation using hydrophones. Additionally, local tilt angles and the orientations of the modules are measu...

  15. A Low Cost Calibration Method for Urban Drainage Models

    DEFF Research Database (Denmark)

    Rasmussen, Michael R.; Thorndahl, Søren; Schaarup-Jensen, Kjeld

    2008-01-01

    The calibration of the hydrological reduction coefficient is examined for a small catchment. The objective is to determine the hydrological reduction coefficient, which is used for describing how much of the precipitation which falls on impervious areas, that actually ends up in the sewer. The re...... to what can be found with intensive in-sewer measurement of rain and runoff. The results also clearly indicate that there is a large variation in hydrological reduction coefficient between different rain events....

  16. A self-sufficient method for calibration of Varian electronic portal imaging device

    Science.gov (United States)

    Sun, Baozhou; Yaddanapudi, Sridhar; Goddu, Sreekrishna M.; Mutic, Sasa

    2015-01-01

    Electronic portal imaging device (EPID) is currently used for dosimetric verification of IMRT fields and linac quality assurance (QA). It is critical to understand the dosimetric response and perform an accurate and robust calibration of EPID. We present the implementation of an efficient method for the calibration and the validation of a Varian EPID, which relies only on data collected with that specific device. The calibration method is based on images obtained with five shifts of EPID panel. With this method, the relative gain (sensitivity) of each element of a detector matrix is calculated and applied on top of the calibration determined with the flood-field procedure. The calibration procedure was verified using a physical wedge inserted in the beam line and the corrected profile shows consistent results with the measurements using a calibrated 2D array. This method does not rely on the beam profile used in the flood-field calibration process, which allows EPID calibration in 10 minutes with no additional equipment compared to at least 2 hours to obtain beam profile and scanning beam equipment requirement with the conventional method.

  17. A self-sufficient method for calibration of Varian electronic portal imaging device

    International Nuclear Information System (INIS)

    Electronic portal imaging device (EPID) is currently used for dosimetric verification of IMRT fields and linac quality assurance (QA). It is critical to understand the dosimetric response and perform an accurate and robust calibration of EPID. We present the implementation of an efficient method for the calibration and the validation of a Varian EPID, which relies only on data collected with that specific device. The calibration method is based on images obtained with five shifts of EPID panel. With this method, the relative gain (sensitivity) of each element of a detector matrix is calculated and applied on top of the calibration determined with the flood-field procedure. The calibration procedure was verified using a physical wedge inserted in the beam line and the corrected profile shows consistent results with the measurements using a calibrated 2D array. This method does not rely on the beam profile used in the flood-field calibration process, which allows EPID calibration in 10 minutes with no additional equipment compared to at least 2 hours to obtain beam profile and scanning beam equipment requirement with the conventional method

  18. Camera calibration method of binocular stereo vision based on OpenCV

    Science.gov (United States)

    Zhong, Wanzhen; Dong, Xiaona

    2015-10-01

    Camera calibration, an important part of the binocular stereo vision research, is the essential foundation of 3D reconstruction of the spatial object. In this paper, the camera calibration method based on OpenCV (open source computer vision library) is submitted to make the process better as a result of obtaining higher precision and efficiency. First, the camera model in OpenCV and an algorithm of camera calibration are presented, especially considering the influence of camera lens radial distortion and decentering distortion. Then, camera calibration procedure is designed to compute those parameters of camera and calculate calibration errors. High-accurate profile extraction algorithm and a checkboard with 48 corners have also been used in this part. Finally, results of calibration program are presented, demonstrating the high efficiency and accuracy of the proposed approach. The results can reach the requirement of robot binocular stereo vision.

  19. In-flight calibration methods used for the Ørsted mission

    DEFF Research Database (Denmark)

    Olsen, Nils; Risbo, Torben; Brauer, Peter;

    2000-01-01

    Several methods have been developed for the in-flight calibration of the Ørsted vector magnetometer. They are based on one of the following principles: a) estimating of the magnetometer constants by means of a scalar calibration (comparison of the vector magnetometer (CSC) with the scalar...

  20. Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities; Metodos de calibracao e de intercomparacao de calibradores de dose utilizados em servicos de medicina nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Alessandro Martins da

    1999-07-01

    Dose calibrators are used in most of the nuclear medicine facilities to determine the amount of radioactivity administered to a patient in a particular investigation or therapeutic procedure. It is therefore of vital importance that the equipment used presents good performance and is regular;y calibrated at a authorized laboratory. This occurs of adequate quality assurance procedures are carried out. Such quality control tests should be performed daily, other biannually or yearly, testing, for example, its accuracy and precision, the reproducibility and response linearity. In this work a commercial dose calibrator was calibrated with solution of radionuclides used in nuclear medicine. Simple instrument tests, such as response linearity and the response variation of the source volume increase at a constant source activity concentration, were performed. This instrument can now be used as a working standard for calibration of other dose calibrators/ An intercomparison procedure was proposed as a method of quality control of dose calibrators used in nuclear medicine facilities. (author)

  1. Calibration methods of plane-parallel ionization chambers used in electron dosimetry

    International Nuclear Information System (INIS)

    The use of linear accelerators in radiotherapy is of great importance in Medicine, and according to international recommendations the electron beam dosimetry has to be performed using plane-parallel ionization chambers, previously calibrated in standard gamma radiation fields at accredited laboratories. In this work, calibration methods of plane-parallel ionization chambers used in dosimetry procedures of high energy electron beams of clinical accelerators were presented, tested and intercompared. The experiments were carried out using gamma radiation beams of 60 Co at the Calibration Laboratory of Clinical Dosemeters at IPEN and electron beams od 4 to 16 MeV at the Radiotherapy Department of Hospital Israelita Albert Einstein, Sao Paulo. A method was chosen to be established at IPEN. Proposals of the calibration procedure, calibration certificate and data sheets are presented. (author)

  2. Improvement on infrared imaging video bolometer by laser calibration method

    International Nuclear Information System (INIS)

    It is necessary to estimate and decrease energy losses while keeping a high performance plasma in a nuclear fusion reactor. Therefore radiation diagnostics are required to estimate the radiation loss as a part of the total energy loss. Our diagnostic, the InfraRed imaging Video Bolometer (IRVB), which has been used in Large Helical Device (LHD), JT-60U and KSTAR, measures the radiation loss from the plasma. First, a metal foil, which is apart of the diagnostic, absorbs radiation energy through an aperture and its temperature risesdue to this energy. An IR camera measures the 2D distribution of the temperature on the foil, then we obtain the irradiance intensity and distribution by solving the heat diffusion equation on the foil. The purpose of our study is the development of the foil calibration analysis with laser for measuring plasma radiation with an IRVB using a Finite Element Model (FEM). This paper shows the improvement from two viewpoints. The first one is from the spatial resolution, and second one is the addition of the time dependent part in the heat diffusion equation with the IRVB calibration of the foil thermal diffusivity. (author)

  3. In Search of Easy-to-Use Methods for Calibrating ADCP's for Velocity and Discharge Measurements

    Science.gov (United States)

    Oberg, K.; ,

    2002-01-01

    A cost-effective procedure for calibrating acoustic Doppler current profilers (ADCP) in the field was presented. The advantages and disadvantages of various methods which are used for calibrating ADCP were discussed. The proposed method requires the use of differential global positioning system (DGPS) with sub-meter accuracy and standard software for collecting ADCP data. The method involves traversing a long (400-800 meter) course at a constant compass heading and speed, while collecting simultaneous DGPS and ADCP data.

  4. Self-calibration method for rotating laser positioning system using interscanning technology and ultrasonic ranging.

    Science.gov (United States)

    Wu, Jun; Yu, Zhijing; Zhuge, Jingchang

    2016-04-01

    A rotating laser positioning system (RLPS) is an efficient measurement method for large-scale metrology. Due to multiple transmitter stations, which consist of a measurement network, the position relationship of these stations must be first calibrated. However, with such auxiliary devices such as a laser tracker, scale bar, and complex calibration process, the traditional calibration methods greatly reduce the measurement efficiency. This paper proposes a self-calibration method for RLPS, which can automatically obtain the position relationship. The method is implemented through interscanning technology by using a calibration bar mounted on the transmitter station. Each bar is composed of three RLPS receivers and one ultrasonic sensor whose coordinates are known in advance. The calibration algorithm is mainly based on multiplane and distance constraints and is introduced in detail through a two-station mathematical model. The repeated experiments demonstrate that the coordinate measurement uncertainty of spatial points by using this method is about 0.1 mm, and the accuracy experiments show that the average coordinate measurement deviation is about 0.3 mm compared with a laser tracker. The accuracy can meet the requirements of most applications, while the calibration efficiency is significantly improved. PMID:27140762

  5. Alternate calibration method of radiochromic EBT3 film for quality assurance verification of clinical radiotherapy treatments

    Science.gov (United States)

    Park, Soah; Kang, Sei-Kwon; Cheong, Kwang-Ho; Hwang, Taejin; Yoon, Jai-Woong; Koo, Taeryool; Han, Tae Jin; Kim, Haeyoung; Lee, Me Yeon; Bae, Hoonsik; Kim, Kyoung Ju

    2016-07-01

    EBT3 film is utilized as a dosimetry quality assurance tool for the verification of clinical radiotherapy treatments. In this work, we suggest a percentage-depth-dose (PDD) calibration method that can calibrate several EBT3 film pieces together at different dose levels because photon beams provide different dose levels at different depths along the axis of the beam. We investigated the feasibility of the film PDD calibration method based on PDD data and compared the results those from the traditional film calibration method. Photon beams at 6 MV were delivered to EBT3 film pieces for both calibration methods. For the PDD-based calibration, the film pieces were placed on solid phantoms at the depth of maximum dose (dmax) and at depths of 3, 5, 8, 12, 17, and 22 cm, and a photon beam was delivered twice, at 100 cGy and 400 cGy, to extend the calibration dose range under the same conditions. Fourteen film pieces, to maintain their consistency, were irradiated at doses ranging from approximately 30 to 400 cGy for both film calibrations. The film pieces were located at the center position on the scan bed of an Epson 1680 flatbed scanner in the parallel direction. Intensity-modulated radiation therapy (IMRT) plans were created, and their dose distributions were delivered to the film. The dose distributions for the traditional method and those for the PDD-based calibration method were evaluated using a Gamma analysis. The PDD dose values using a CC13 ion chamber and those obtained by using a FC65-G Farmer chamber and measured at the depth of interest produced very similar results. With the objective test criterion of a 1% dosage agreement at 1 mm, the passing rates for the four cases of the three IMRT plans were essentially identical. The traditional and the PDD-based calibrations provided similar plan verification results. We also describe another alternative for calibrating EBT3 films, i.e., a PDD-based calibration method that provides an easy and time-saving approach

  6. Calibration methods and tools for KM3NeT

    Directory of Open Access Journals (Sweden)

    Kulikovskiy Vladimir

    2016-01-01

    Full Text Available The KM3NeT detectors, ARCA and ORCA, composed of several thousands digital optical modules, are in the process of their realization in the Mediterranean Sea. Each optical module contains 31 3-inch photomultipliers. Readout of the optical modules and other detector components is synchronized at the level of sub-nanoseconds. The position of the module is measured by acoustic piezo detectors inside the module and external acoustic emitters installed on the bottom of the sea. The orientation of the module is obtained with an internal attitude and heading reference system chip. Detector calibration, i.e. timing, positioning and sea-water properties, is overviewed in this talk and discussed in detail in this conference. Results of the procedure applied to the first detector unit ready for installation in the deep sea will be shown.

  7. Radon in air calibration procedure: A primary method

    International Nuclear Information System (INIS)

    A procedure has been developed for preparing 3- to 9-iota volumes of air under natural conditions with a known concentration of /sup 222/Rn to be used for calibrating radon systems. Air is passed into a plastic bag through a standard /sup 226/Ra solution (prepared by the U.S. National Bureau of Standards) contained in an emanation flask. This plastic bag retains /sup 222/Rn with little loss into or through the bag walls. The mean ratios of the /sup 222/Rn in the air at 2 and 7 days after filling to that immediately after filling were -.992 +- 0.006 and 0.969 +- 0.008, which suggests a rate of radon loss into the bag of 0.4 +- 0.1%/day

  8. Sum of ranking differences (SRD) to ensemble multivariate calibration model merits for tuning parameter selection and comparing calibration methods

    Energy Technology Data Exchange (ETDEWEB)

    Kalivas, John H., E-mail: kalijohn@isu.edu [Department of Chemistry, Idaho State University, Pocatello, ID 83209 (United States); Héberger, Károly [Research Centre for Natural Sciences, Hungarian Academy of Sciences, Pusztaszeri út 59-67, 1025 Budapest (Hungary); Andries, Erik [Center for Advanced Research Computing, University of New Mexico, Albuquerque, NM 87106 (United States); Department of Mathematics, Central New Mexico Community College, Albuquerque, NM 87106 (United States)

    2015-04-15

    Highlights: • Sum of ranking differences (SRD) used for tuning parameter selection based on fusion of multicriteria. • No weighting scheme is needed for the multicriteria. • SRD allows automatic selection of one model or a collection of models if so desired. • SRD allows simultaneous comparison of different calibration methods with tuning parameter selection. • New MATLAB programs are described and made available. - Abstract: Most multivariate calibration methods require selection of tuning parameters, such as partial least squares (PLS) or the Tikhonov regularization variant ridge regression (RR). Tuning parameter values determine the direction and magnitude of respective model vectors thereby setting the resultant predication abilities of the model vectors. Simultaneously, tuning parameter values establish the corresponding bias/variance and the underlying selectivity/sensitivity tradeoffs. Selection of the final tuning parameter is often accomplished through some form of cross-validation and the resultant root mean square error of cross-validation (RMSECV) values are evaluated. However, selection of a “good” tuning parameter with this one model evaluation merit is almost impossible. Including additional model merits assists tuning parameter selection to provide better balanced models as well as allowing for a reasonable comparison between calibration methods. Using multiple merits requires decisions to be made on how to combine and weight the merits into an information criterion. An abundance of options are possible. Presented in this paper is the sum of ranking differences (SRD) to ensemble a collection of model evaluation merits varying across tuning parameters. It is shown that the SRD consensus ranking of model tuning parameters allows automatic selection of the final model, or a collection of models if so desired. Essentially, the user’s preference for the degree of balance between bias and variance ultimately decides the merits used in SRD

  9. A direct micropipette-based calibration method for atomic force microscope cantilevers

    Energy Technology Data Exchange (ETDEWEB)

    Liu Baoyu; Yu Yan; Yao Dakang; Shao Jinyu [Department of Biomedical Engineering, Washington University, Saint Louis, Missouri 63130 (United States)

    2009-06-15

    In this report, we describe a direct method for calibrating atomic force microscope (AFM) cantilevers with the micropipette aspiration technique (MAT). A closely fitting polystyrene bead inside a micropipette is driven by precisely controlled hydrostatic pressures to apply known loads on the sharp tip of AFM cantilevers, thus providing a calibration at the most functionally relevant position. The new method is capable of calibrating cantilevers with spring constants ranging from 0.01 to hundreds of newtons per meter. Under appropriate loading conditions, this new method yields measurement accuracy and precision both within 10%, with higher performance for softer cantilevers. Furthermore, this method may greatly enhance the accuracy and precision of calibration for colloidal probes.

  10. Nanoscale Calibration Standards and Methods: Dimensional and Related Measurements in the Micro- and Nanometer Range

    Science.gov (United States)

    Wilkening, Günter; Koenders, Ludger

    2005-08-01

    The quantitative determination of the properties of micro- and nanostructures is essential in research and development. It is also a prerequisite in process control and quality assurance in industry. The knowledge of the geometrical dimensions of structures in most cases is the base, to which other physical and chemical properties are linked. Quantitative measurements require reliable and stable instruments, suitable measurement procedures as well as appropriate calibration artefacts and methods. The seminar "NanoScale 2004" (6th Seminar on Quantitative Microscopy and 2nd Seminar on Nanoscale Calibration Standards and Methods) at the National Metrology Institute (Physikalisch-Technische Bundesanstalt PTB), Braunschweig, Germany, continues the series of seminars on Quantitative Microscopy. The series stimulates the exchange of information between manufacturers of relevant hard- and software and the users in science and industry. Topics addressed in these proceedings are a) the application of quantitative measurements and measurement problems in: microelectronics, microsystems technology, nano/quantum/molecular electronics, chemistry, biology, medicine, environmental technology, materials science, surface processing b) calibration & correction methods: calibration methods, calibration standards, calibration procedures, traceable measurements, standardization, uncertainty of measurements c) instrumentation and methods: novel/improved instruments and methods, reproducible probe/sample positioning, position-measuring systems, novel/improved probe/detector systems, linearization methods, image processing

  11. Bifurcation physics of magnetic islands and stochasticity explored by heat pulse propagation studies in toroidal plasmas

    Science.gov (United States)

    Ida, K.; Kobayashi, T.; Yoshinuma, M.; Suzuki, Y.; Narushima, Y.; Evans, T. E.; Ohdachi, S.; Tsuchiya, H.; Inagaki, S.; Itoh, K.

    2016-09-01

    Bifurcation physics of a magnetic island was investigated using the heat pulse propagation technique produced by the modulation of electron cyclotron heating. There are two types of bifurcation phenomena observed in a large helical device (LHD) and DIII-D. One is a bifurcation of the magnetic topology between nested and stochastic fields. The nested state is characterized by the bi-directional (inward and outward) propagation of the heat pulse with slow propagation speed. The stochastic state is characterized by the fast propagation of the heat pulse with electron temperature flattening. The other bifurcation is between the magnetic island with larger thermal diffusivity and that with smaller thermal diffusivity. The damping of toroidal flow is observed at the O-point of the magnetic island both in helical plasmas and in tokamak plasmas during a mode locking phase with strong flow shears at the boundary of the magnetic island. Associated with the stochastization of the magnetic field, the abrupt damping of toroidal flow is observed in LHD. The toroidal flow shear shows a linear decay, while the ion temperature gradient shows an exponential decay. This observation suggests that this flow damping is due to the change in the non-diffusive term of momentum transport.

  12. Novel Method for Processing the Dynamic Calibration Signal of Pressure Sensor.

    Science.gov (United States)

    Wang, Zhongyu; Li, Qiang; Wang, Zhuoran; Yan, Hu

    2015-07-21

    Dynamic calibration is one of the important ways to acquire the dynamic performance parameters of a pressure sensor. This research focuses on the processing method for the output of calibrated pressure sensor, and mainly attempts to solve the problem of extracting the true information of step response under strong interference noise. A dynamic calibration system based on a shock tube is established to excite the time-domain response signal of a calibrated pressure sensor. A key processing on difference modeling is applied for the obtained signal, and several generating sequences are established. A fusion process for the generating sequences is then undertaken, and the true information of the step response of the calibrated pressure sensor can be obtained. Finally, by implementing the common QR decomposition method to deal with the true information, a dynamic model characterizing the dynamic performance of the calibrated pressure sensor is established. A typical pressure sensor was used to perform calibration tests and a frequency-domain experiment for the sensor was also conducted. Results show that the proposed method could effectively filter strong interference noise in the output of the sensor and the corresponding dynamic model could effectively characterize the dynamic performance of the pressure sensor.

  13. Calibration Methods Used in Cancer Simulation Models and Suggested Reporting Guidelines

    Science.gov (United States)

    Stout, Natasha K.; Knudsen, Amy B.; Kong, Chung Yin (Joey); McMahon, Pamela M.; Gazelle, G. Scott

    2009-01-01

    Background Increasingly, computer simulation models are used for economic and policy evaluation in cancer prevention and control. A model’s predictions of key outcomes such as screening effectiveness depends on the values of unobservable natural history parameters. Calibration is the process of determining the values of unobservable parameters by constraining model output to replicate observed data. Because there are many approaches for model calibration and little consensus on best practices, we surveyed the literature to catalogue the use and reporting of these methods in cancer simulation models. Methods We conducted a MEDLINE search (1980 through 2006) for articles on cancer screening models and supplemented search results with articles from our personal reference databases. For each article, two authors independently abstracted pre-determined items using a standard form. Data items included cancer site, model type, methods used for determination of unobservable parameter values, and description of any calibration protocol. All authors reached consensus on items of disagreement. Reviews and non-cancer models were excluded. Articles describing analytical models which estimate parameters with statistical approaches (e.g., maximum likelihood) were catalogued separately. Models that included unobservable parameters were analyzed and classified by whether calibration methods were reported and if so, the methods used. Results The review process yielded 154 articles that met our inclusion criteria and of these, we concluded that 131 may have used calibration methods to determine model parameters. Although the term “calibration” was not always used, descriptions of calibration or “model fitting” were found in 50% (n=66) of the articles with an additional 16% (n=21) providing a reference to methods. Calibration target data were identified in nearly all of these articles. Other methodologic details such as the goodness-of-fit metric were discussed in 54% (n=47

  14. Method Specific Calibration Corrects for DNA Extraction Method Effects on Relative Telomere Length Measurements by Quantitative PCR

    Science.gov (United States)

    Holland, Rebecca; Underwood, Sarah; Fairlie, Jennifer; Psifidi, Androniki; Ilska, Joanna J.; Bagnall, Ainsley; Whitelaw, Bruce; Coffey, Mike; Banos, Georgios; Nussey, Daniel H.

    2016-01-01

    Telomere length (TL) is increasingly being used as a biomarker in epidemiological, biomedical and ecological studies. A wide range of DNA extraction techniques have been used in telomere experiments and recent quantitative PCR (qPCR) based studies suggest that the choice of DNA extraction method may influence average relative TL (RTL) measurements. Such extraction method effects may limit the use of historically collected DNA samples extracted with different methods. However, if extraction method effects are systematic an extraction method specific (MS) calibrator might be able to correct for them, because systematic effects would influence the calibrator sample in the same way as all other samples. In the present study we tested whether leukocyte RTL in blood samples from Holstein Friesian cattle and Soay sheep measured by qPCR was influenced by DNA extraction method and whether MS calibration could account for any observed differences. We compared two silica membrane-based DNA extraction kits and a salting out method. All extraction methods were optimized to yield enough high quality DNA for TL measurement. In both species we found that silica membrane-based DNA extraction methods produced shorter RTL measurements than the non-membrane-based method when calibrated against an identical calibrator. However, these differences were not statistically detectable when a MS calibrator was used to calculate RTL. This approach produced RTL measurements that were highly correlated across extraction methods (r > 0.76) and had coefficients of variation lower than 10% across plates of identical samples extracted by different methods. Our results are consistent with previous findings that popular membrane-based DNA extraction methods may lead to shorter RTL measurements than non-membrane-based methods. However, we also demonstrate that these differences can be accounted for by using an extraction method-specific calibrator, offering researchers a simple means of accounting for

  15. Single Vector Calibration System for Multi-Axis Load Cells and Method for Calibrating a Multi-Axis Load Cell

    Science.gov (United States)

    Parker, Peter A. (Inventor)

    2003-01-01

    A single vector calibration system is provided which facilitates the calibration of multi-axis load cells, including wind tunnel force balances. The single vector system provides the capability to calibrate a multi-axis load cell using a single directional load, for example loading solely in the gravitational direction. The system manipulates the load cell in three-dimensional space, while keeping the uni-directional calibration load aligned. The use of a single vector calibration load reduces the set-up time for the multi-axis load combinations needed to generate a complete calibration mathematical model. The system also reduces load application inaccuracies caused by the conventional requirement to generate multiple force vectors. The simplicity of the system reduces calibration time and cost, while simultaneously increasing calibration accuracy.

  16. Quantum efficiency calibration of opto-electronic detector by means of correlated photons method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A new calibration method of detectors can be realized by using correlated photons generated in spontaneous parametric down-conversion (SPDC) effect of nonlinear crystal.An absolute calibration system of detector quantum efficiency is performed.And its principle and experimental setup are introduced.A continuouswave (CW) ultraviolet (351 nm),diode-pumped,frequency-doubled,and solid-state laser is used to pump BBO crystal.The quantum efficiencies of the photomultiplier at 633,702,and 789 nm are measured respectively.The coincidence peaks are observed using coincidence circuit.Some measurement factors including the filter bandwidth of trigger channel,the detector position alignment and polarization of the pump light are analyzed.The uncertainties of this calibration method are also analyzed,and the relative uncertainties of total calibration are less than 5.8%.The accuracy of this method could be improved in the future.

  17. GMI Instrument Spin Balance Method, Optimization, Calibration, and Test

    Science.gov (United States)

    Ayari, Laoucet; Kubitschek, Michael; Ashton, Gunnar; Johnston, Steve; Debevec, Dave; Newell, David; Pellicciotti, Joseph

    2014-01-01

    The Global Microwave Imager (GMI) instrument must spin at a constant rate of 32 rpm continuously for the 3 year mission life. Therefore, GMI must be very precisely balanced about the spin axis and CG to maintain stable scan pointing and to minimize disturbances imparted to the spacecraft and attitude control on-orbit. The GMI instrument is part of the core Global Precipitation Measurement (GPM) spacecraft and is used to make calibrated radiometric measurements at multiple microwave frequencies and polarizations. The GPM mission is an international effort managed by the National Aeronautics and Space Administration (NASA) to improve climate, weather, and hydro-meteorological predictions through more accurate and frequent precipitation measurements. Ball Aerospace and Technologies Corporation (BATC) was selected by NASA Goddard Space Flight Center to design, build, and test the GMI instrument. The GMI design has to meet a challenging set of spin balance requirements and had to be brought into simultaneous static and dynamic spin balance after the entire instrument was already assembled and before environmental tests began. The focus of this contribution is on the analytical and test activities undertaken to meet the challenging spin balance requirements of the GMI instrument. The novel process of measuring the residual static and dynamic imbalances with a very high level of accuracy and precision is presented together with the prediction of the optimal balance masses and their locations.

  18. Automated calibration methods for robotic multisensor landmine detection

    Science.gov (United States)

    Keranen, Joe G.; Miller, Jonathan; Schultz, Gregory; Topolosky, Zeke

    2007-04-01

    Both force protection and humanitarian demining missions require efficient and reliable detection and discrimination of buried anti-tank and anti-personnel landmines. Widely varying surface and subsurface conditions, mine types and placement, as well as environmental regimes challenge the robustness of the automatic target recognition process. In this paper we present applications created for the U.S. Army Nemesis detection platform. Nemesis is an unmanned rubber-tracked vehicle-based system designed to eradicate a wide variety of anti-tank and anti-personnel landmines for humanitarian demining missions. The detection system integrates advanced ground penetrating synthetic aperture radar (GPSAR) and electromagnetic induction (EMI) arrays, highly accurate global and local positioning, and on-board target detection/classification software on the front loader of a semi-autonomous UGV. An automated procedure is developed to estimate the soil's dielectric constant using surface reflections from the ground penetrating radar. The results have implications not only for calibration of system data acquisition parameters, but also for user awareness and tuning of automatic target recognition detection and discrimination algorithms.

  19. A Flexile and High Precision Calibration Method for Binocular Structured Light Scanning System

    Directory of Open Access Journals (Sweden)

    Jianying Yuan

    2014-01-01

    Full Text Available 3D (three-dimensional structured light scanning system is widely used in the field of reverse engineering, quality inspection, and so forth. Camera calibration is the key for scanning precision. Currently, 2D (two-dimensional or 3D fine processed calibration reference object is usually applied for high calibration precision, which is difficult to operate and the cost is high. In this paper, a novel calibration method is proposed with a scale bar and some artificial coded targets placed randomly in the measuring volume. The principle of the proposed method is based on hierarchical self-calibration and bundle adjustment. We get initial intrinsic parameters from images. Initial extrinsic parameters in projective space are estimated with the method of factorization and then upgraded to Euclidean space with orthogonality of rotation matrix and rank 3 of the absolute quadric as constraint. Last, all camera parameters are refined through bundle adjustment. Real experiments show that the proposed method is robust, and has the same precision level as the result using delicate artificial reference object, but the hardware cost is very low compared with the current calibration method used in 3D structured light scanning system.

  20. Comparative study among calibration methods of clinical applicators of beta radiation

    International Nuclear Information System (INIS)

    90Sr+90Y clinical applicators are instruments used in brachytherapy procedures and they have to be periodically calibrated, according to international standards and recommendations. In this work, four calibration methods of dermatological and ophthalmic applicators were studied, comparing the results with those given by the calibration certificates of the manufacturers. The methods included the use of the standard applicator of the Calibration Laboratory (LCI), calibrated by the National Institute of Standards and Technology; an Amersham applicator (LCI) as reference; a mini-extrapolation chamber developed at LCI as an absolute standard; and thermoluminescent dosimetry. The mini-extrapolation chamber and a PTW commercial extrapolation chamber were studied in relation to their performance through quality control tests of their response, as leakage current, repeatability and reproducibility. The distribution of the depth dose in water, that presents high importance in dosimetry of clinical applicators, was determined using the mini extrapolation chamber and the thermoluminescent dosimeters. The results obtained were considered satisfactory for the both cases, and comparable to the data of the IAEA (2002) standard. Furthermore, a dosimetry postal kit was developed for the calibration of clinical applicators using the thermoluminescent technique, to be sent to clinics and hospitals, without the need of the transport of the sources to IPEN for calibration. (author)

  1. A Method to Calibrate Beam Position Monitor at HLS 200 MeV LINAC

    CERN Document Server

    Li, Ji-Hao; He, Duo-hui; Jin, Kai; Lu, Ping; Sun Bao Gen; Wang, Jianping; Wang, Yong; Zheng, P

    2005-01-01

    In order to improve injection efficiency of HLS 200Mev LINAC, we redesign a new strip line beam position monitor system, which is consisted of a strip line structure and a signal processing system. We decide on an online calibration method based on beam to find out the geometry centre displacement and relative gain offset. Before the BPM testing bench has been prepared, we make a simulation based on the model accounted for all factors influencing signal amplitudes and get the calibrating results. At last, we analyze the nonlinearity effect on the calibration results.

  2. Easy calibration method of vision system for in-situ measurement of strain of thin films

    Institute of Scientific and Technical Information of China (English)

    Jun-Hyub PARK; Dong-Joong KANG; Myung-Soo SHIN; Sung-Jo LIM; Son-Cheol YU; Kwang-Soo LEE; Jong-Eun HA; Sung-Hoon CHOA

    2009-01-01

    An easy calibration method was presented for in-situ measurement of displacement in the order of nanometer during micro-tensile test for thin films by using CCD camera as a sensing device. The calibration of the sensing camera in the system is a central element part to measure displacement in the order of nanometer using images taken with the camera. This was accomplished by modeling the optical projection through the camera lens and relative locations between the object and camera in 3D space. A set of known 3D points on a plane where the film is located on is projected to an image plane as input data. These points, known as a calibration points, are then used to estimate the projection parameters of the camera. In the measurement system of the micro-scale by CCD camera, the calibration data acquisition and one-to-one matching steps between the image and 3D planes need precise data extraction procedures and repetitive user's operation to calibrate the measuring devices. The lack of the robust image feature extraction and easy matching prevent the practical use of these methods. A data selection method was proposed to overcome these limitations and offer an easy and convenient calibration of a vision system that has the CCD camera and the 3D reference plane with calibration marks of circular type on the surface of the plane. The method minimizes the user's intervention such as the fine tuning of illumination system and provides an efficient calibration method of the vision system for in-situ axial displacement measurement of the micro-tensile materials.

  3. A new method for the absolute radiance calibration for UV-vis measurements of scattered sunlight

    Science.gov (United States)

    Wagner, T.; Beirle, S.; Dörner, S.; Penning de Vries, M.; Remmers, J.; Rozanov, A.; Shaiganfar, R.

    2015-10-01

    Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds, and the shortwave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV-vis instruments that measure the spectrally resolved sky radiance, for example zenith sky differential optical absorption spectroscopy (DOAS) instruments or multi-axis (MAX)-DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method, clear-sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about < 7 %. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements be constant and known.

  4. Establishment of a primary reference solar cell calibration technique in Korea: methods, results and comparison with WPVS qualified laboratories

    Science.gov (United States)

    Ahn, SeungKyu; Ahn, SeJin; Yun, Jae Ho; Lee, Dong-Hoon; Winter, Stefan; Igari, Sanekazu; Yoon, KyungHoon

    2014-06-01

    A primary reference solar cell calibration technique recently established at the Korea Institute of Energy Research in Korea is introduced. This calibration technique is an indoor method that uses a highly collimated continuous-type solar simulator and absolute cavity radiometer traceable to the World Radiometric Reference. The results obtained using this calibration technique are shown with a precise uncertainty analysis, and the system configuration and calibration procedures are introduced. The calibration technique avoids overestimating the short-circuit current of a reference solar cell due to multiple reflections of incident simulator light using a novel method. In addition, the uncertainty analysis indicates that the calibration technique has an expanded uncertainty of approximately 0.7% with a coverage factor of k = 2 for a c-Si reference cell calibration. In addition, the developed primary reference solar cell calibration technique was compared with other techniques established in the World Photovoltaic Scale (WPVS) qualified calibration laboratories to verify its validity and reliability.

  5. A new and simple calibration-independent method for measuring the beam energy of a cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Gagnon, Katherine, E-mail: kgagnon1@ualberta.c [Cross Cancer Institute, Edmonton PET Centre, University of Alberta, Edmonton, AB, T6G 1Z2 (Canada); Jensen, Mikael; Thisgaard, Helge [Hevesy Laboratory, Risoe-DTU, Technical University of Denmark, Frederiksborgvej 399, DK-4000 Roskilde (Denmark); Publicover, Julia; Lapi, Suzanne [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); McQuarrie, Steve A. [Cross Cancer Institute, Edmonton PET Centre, University of Alberta, Edmonton, AB, T6G 1Z2 (Canada); Ruth, Thomas J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada)

    2011-01-15

    This work recommends a new and simple-to-perform method for measuring the beam energy of an accelerator. The proposed method requires the irradiation of two monitor foils interspaced by an energy degrader. The primary advantage of the proposed method, which makes this method unique from previous energy evaluation strategies that employ the use of monitor foils, is that this method is independent of the detector efficiency calibration. This method was evaluated by performing proton activation of {sup nat}Cu foils using both a cyclotron and a tandem Van de Graaff accelerator. The monitor foil activities were read using a dose calibrator set to an arbitrary calibration setting. Excellent agreement was noted between the nominal and measured proton energies.

  6. A new and simple calibration-independent method for measuring the beam energy of a cyclotron.

    Science.gov (United States)

    Gagnon, Katherine; Jensen, Mikael; Thisgaard, Helge; Publicover, Julia; Lapi, Suzanne; McQuarrie, Steve A; Ruth, Thomas J

    2011-01-01

    This work recommends a new and simple-to-perform method for measuring the beam energy of an accelerator. The proposed method requires the irradiation of two monitor foils interspaced by an energy degrader. The primary advantage of the proposed method, which makes this method unique from previous energy evaluation strategies that employ the use of monitor foils, is that this method is independent of the detector efficiency calibration. This method was evaluated by performing proton activation of (nat)Cu foils using both a cyclotron and a tandem Van de Graaff accelerator. The monitor foil activities were read using a dose calibrator set to an arbitrary calibration setting. Excellent agreement was noted between the nominal and measured proton energies. PMID:20926304

  7. Development of in-situ calibration method's algorithm for thermal imager

    OpenAIRE

    Dzikovska, Yu.; Hots, N.

    2015-01-01

    The effect of impact factors on the output signal of the radiation receiver is analyzed. Necessity to do additional in-situ calibration of thermal imager by using the standard extended area grey emitter is justified. In-situ calibration method's algorithm for thermal imager is developed. It helps to eliminate the effect of impact factors on the measurement results of temperature gradient. The requirements to the standard extended area emitter are formulated.

  8. A Focusing Method in the Calibration Process of Image Sensors Based on IOFBs

    OpenAIRE

    Pedro R. Fernández; Lázaro, José L.; Alfredo Gardel; Ángel E. Cano; Ignacio Bravo

    2009-01-01

    A focusing procedure in the calibration process of image sensors based on Incoherent Optical Fiber Bundles (IOFBs) is described using the information extracted from fibers. These procedures differ from any other currently known focusing method due to the non spatial in-out correspondence between fibers, which produces a natural codification of the image to transmit. Focus measuring is essential prior to carrying out calibration in order to guarantee accurate processing and decoding. Four algo...

  9. Improvements to and Comparison of Static Terrestrial LiDAR Self-Calibration Methods

    Directory of Open Access Journals (Sweden)

    Preston Hartzell

    2013-05-01

    Full Text Available Terrestrial laser scanners are sophisticated instruments that operate much like high-speed total stations. It has previously been shown that unmodelled systematic errors can exist in modern terrestrial laser scanners that deteriorate their geometric measurement precision and accuracy. Typically, signalised targets are used in point-based self-calibrations to identify and model the systematic errors. Although this method has proven its effectiveness, a large quantity of signalised targets is required and is therefore labour-intensive and limits its practicality. In recent years, feature-based self-calibration of aerial, mobile terrestrial, and static terrestrial laser scanning systems has been demonstrated. In this paper, the commonalities and differences between point-based and plane-based self-calibration (in terms of model identification and parameter correlation are explored. The results of this research indicate that much of the knowledge from point-based self-calibration can be directly transferred to plane-based calibration and that the two calibration approaches are nearly equivalent. New network configurations, such as the inclusion of tilted scans, were also studied and prove to be an effective means for strengthening the self-calibration solution, and improved recoverability of the horizontal collimation axis error for hybrid scanners, which has always posed a challenge in the past.

  10. Induced Dual-Nanospray: A Novel Internal Calibration Method for Convenient and Accurate Mass Measurement

    Science.gov (United States)

    Li, Yafeng; Zhang, Ning; Zhou, Yueming; Wang, Jianing; Zhang, Yiming; Wang, Jiyun; Xiong, Caiqiao; Chen, Suming; Nie, Zongxiu

    2013-09-01

    Accurate mass information is of great importance in the determination of unknown compounds. An effective and easy-to-control internal mass calibration method will dramatically benefit accurate mass measurement. Here we reported a simple induced dual-nanospray internal calibration device which has the following three advantages: (1) the two sprayers are in the same alternating current field; thus both reference ions and sample ions can be simultaneously generated and recorded. (2) It is very simple and can be easily assembled. Just two metal tubes, two nanosprayers, and an alternating current power supply are included. (3) With the low-flow-rate character and the versatility of nanoESI, this calibration method is capable of calibrating various samples, even untreated complex samples such as urine and other biological samples with small sample volumes. The calibration errors are around 1 ppm in positive ion mode and 3 ppm in negative ion mode with good repeatability. This new internal calibration method opens up new possibilities in the determination of unknown compounds, and it has great potential for the broad applications in biological and chemical analysis.

  11. Local Strategy Combined with a Wavelength Selection Method for Multivariate Calibration

    Directory of Open Access Journals (Sweden)

    Haitao Chang

    2016-06-01

    Full Text Available One of the essential factors influencing the prediction accuracy of multivariate calibration models is the quality of the calibration data. A local regression strategy, together with a wavelength selection approach, is proposed to build the multivariate calibration models based on partial least squares regression. The local algorithm is applied to create a calibration set of spectra similar to the spectrum of an unknown sample; the synthetic degree of grey relation coefficient is used to evaluate the similarity. A wavelength selection method based on simple-to-use interactive self-modeling mixture analysis minimizes the influence of noisy variables, and the most informative variables of the most similar samples are selected to build the multivariate calibration model based on partial least squares regression. To validate the performance of the proposed method, ultraviolet-visible absorbance spectra of mixed solutions of food coloring analytes in a concentration range of 20–200 µg/mL is measured. Experimental results show that the proposed method can not only enhance the prediction accuracy of the calibration model, but also greatly reduce its complexity.

  12. Local Strategy Combined with a Wavelength Selection Method for Multivariate Calibration.

    Science.gov (United States)

    Chang, Haitao; Zhu, Lianqing; Lou, Xiaoping; Meng, Xiaochen; Guo, Yangkuan; Wang, Zhongyu

    2016-01-01

    One of the essential factors influencing the prediction accuracy of multivariate calibration models is the quality of the calibration data. A local regression strategy, together with a wavelength selection approach, is proposed to build the multivariate calibration models based on partial least squares regression. The local algorithm is applied to create a calibration set of spectra similar to the spectrum of an unknown sample; the synthetic degree of grey relation coefficient is used to evaluate the similarity. A wavelength selection method based on simple-to-use interactive self-modeling mixture analysis minimizes the influence of noisy variables, and the most informative variables of the most similar samples are selected to build the multivariate calibration model based on partial least squares regression. To validate the performance of the proposed method, ultraviolet-visible absorbance spectra of mixed solutions of food coloring analytes in a concentration range of 20-200 µg/mL is measured. Experimental results show that the proposed method can not only enhance the prediction accuracy of the calibration model, but also greatly reduce its complexity. PMID:27271636

  13. A Visual Servoing-Based Method for ProCam Systems Calibration

    Science.gov (United States)

    Berry, Francois; Aider, Omar Ait; Mosnier, Jeremie

    2013-01-01

    Projector-camera systems are currently used in a wide field of applications, such as 3D reconstruction and augmented reality, and can provide accurate measurements, depending on the configuration and calibration. Frequently, the calibration task is divided into two steps: camera calibration followed by projector calibration. The latter still poses certain problems that are not easy to solve, such as the difficulty in obtaining a set of 2D–3D points to compute the projection matrix between the projector and the world. Existing methods are either not sufficiently accurate or not flexible. We propose an easy and automatic method to calibrate such systems that consists in projecting a calibration pattern and superimposing it automatically on a known printed pattern. The projected pattern is provided by a virtual camera observing a virtual pattern in an OpenGL model. The projector displays what the virtual camera visualizes. Thus, the projected pattern can be controlled and superimposed on the printed one with the aid of visual servoing. Our experimental results compare favorably with those of other methods considering both usability and accuracy. PMID:24084121

  14. Calibration Methods for Reliability-Based Design Codes

    DEFF Research Database (Denmark)

    Gayton, N.; Mohamed, A.; Sørensen, John Dalsgaard;

    2004-01-01

    efficient methods. In our approach, the accuracy is balanced with time efficiency by the mean of iterative scheme using approximate methods. The presented ideas are clarified by four numerical examples of parabolic performance function, column buckling, stability of submarine shells and structural elements....

  15. Calibration of the photometric method of heavy ion charge measurements in emulsion using a CCD camera

    CERN Document Server

    Kudzia, D; Wilczynski, H

    2002-01-01

    A previously developed method of heavy ion charge measurements in emulsion has been significantly improved. The charge measurements are based on analysis of photometric profiles of the particle tracks in emulsion. These profiles are obtained using a CCD camera mounted on an optical microscope. So far, the manual charge determination by delta ray counting had to be used for calibration of the photometric method. In this paper a complete procedure for calibration of the photometric method is shown, without resorting to the manual method.

  16. A New Calibration Method for Microphone Array with Gain, Phase, and Position Errors

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Microphone array can be used in sound source localization and separation. But gain, phase, and position errors can seriously influence the performance of localization algorithms such as multiple signal classification (MUSIC) algorithm. In this paper, a new calibration method for microphone array with gain, phase, and position errors is proposed. Unlike traditional calibration methods for antenna array, the proposed method can be used in the broadband and near-field signal model such as microphone array with arbitrary sensor geometries in one plane. Computer simulations are presented and simulation results show the new method having good performance.

  17. [In-Flight Radiometric Calibration for ZY-3 Satellite Multispectral Sensor by Modified Reflectance-Based Method].

    Science.gov (United States)

    Han, Jie; Xie, Yong; Gu, Xing-fa; Yu, Tao; Liu, Qi-yue; Gao, Rong-jun

    2015-03-01

    Through integrating multi-spectral sensor characteristics of ZY-3 satellite, a modified reflectance-based method is proposed and used to achieve ZY-3 satellite multispectral sensor in-flight radiometric calibration. This method chooses level 1A image as data source and establishes geometric model to get an accurate observation geometric parameters at calibration site according to the information provided in image auxiliary documentation, which can reduce the influences on the calibration accuracy from image resampling and observation geometry errors. We use two-point and multi-points methods to calculate the absolute radiometric calibration coefficients of ZY-3 satellite multispectral sensor based on the large campaign at Dongying city, Shan Dong province. Compared with ZY-3 official calibration coefficients, multi-points method has higher accuracy than two-point method. Through analyzing the dispersion between each calibration point and the fitting line, we find that the residual error of water calibration site is larger than others, which of green band is approximately 67.39%. Treating water calibration site as an error, we filter it out using 95.4% confidence level as standard and recalculate the calibration coefficients with multi-points method. The final calibration coefficients show that the relative differences of the first three bands are less than 2% and the last band is less than 5%, which manifests that the proposed radiometric calibration method can obtain accurate and reliable calibration coefficients and is useful for other similar satellites in future.

  18. Calibration of a multichannel MEG system based on the signal space separation method.

    Science.gov (United States)

    Chella, F; Zappasodi, F; Marzetti, L; Della Penna, S; Pizzella, V

    2012-08-01

    For an efficient use of multichannel MEG systems, an accurate sensor calibration is extremely important. This includes the knowledge of both channel sensitivities and channel arrangement, which can deviate from original system plans, e.g., because of thermal stresses. In this paper, we propose a new solution to the calibration of a multichannel MEG sensor array based on the signal space separation (SSS) method. It has been shown that an inaccurate knowledge of sensor calibration limits the performances of the SSS method, resulting in a mismatch between the measured neuromagnetic field and its SSS reconstruction. Given a set of known magnetic sources, we show that an objective function, which strongly depends on sensor geometry, can be derived from the principal angle between the measured vector signal and the SSS basis. Hence, the MEG sensor array calibration is carried out by minimizing the objective function through a standard large-scale optimization technique. Details on the magnetic sources and calibration process are presented here. Finally, an application to the calibration of the 153-channel whole-head MEG system installed at the University of Chieti is discussed. PMID:22797687

  19. An efficient calibration method for SQUID measurement system using three orthogonal Helmholtz coils

    Science.gov (United States)

    Hua, Li; Shu-Lin, Zhang; Chao-Xiang, Zhang; Xiang-Yan, Kong; Xiao-Ming, Xie

    2016-06-01

    For a practical superconducting quantum interference device (SQUID) based measurement system, the Tesla/volt coefficient must be accurately calibrated. In this paper, we propose a highly efficient method of calibrating a SQUID magnetometer system using three orthogonal Helmholtz coils. The Tesla/volt coefficient is regarded as the magnitude of a vector pointing to the normal direction of the pickup coil. By applying magnetic fields through a three-dimensional Helmholtz coil, the Tesla/volt coefficient can be directly calculated from magnetometer responses to the three orthogonally applied magnetic fields. Calibration with alternating current (AC) field is normally used for better signal-to-noise ratio in noisy urban environments and the results are compared with the direct current (DC) calibration to avoid possible effects due to eddy current. In our experiment, a calibration relative error of about 6.89 × 10‑4 is obtained, and the error is mainly caused by the non-orthogonality of three axes of the Helmholtz coils. The method does not need precise alignment of the magnetometer inside the Helmholtz coil. It can be used for the multichannel magnetometer system calibration effectively and accurately. Project supported by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences (Grant No. XDB04020200) and the Shanghai Municipal Science and Technology Commission Project, China (Grant No. 15DZ1940902).

  20. An efficient calibration method for SQUID measurement system using three orthogonal Helmholtz coils

    Science.gov (United States)

    Hua, Li; Shu-Lin, Zhang; Chao-Xiang, Zhang; Xiang-Yan, Kong; Xiao-Ming, Xie

    2016-06-01

    For a practical superconducting quantum interference device (SQUID) based measurement system, the Tesla/volt coefficient must be accurately calibrated. In this paper, we propose a highly efficient method of calibrating a SQUID magnetometer system using three orthogonal Helmholtz coils. The Tesla/volt coefficient is regarded as the magnitude of a vector pointing to the normal direction of the pickup coil. By applying magnetic fields through a three-dimensional Helmholtz coil, the Tesla/volt coefficient can be directly calculated from magnetometer responses to the three orthogonally applied magnetic fields. Calibration with alternating current (AC) field is normally used for better signal-to-noise ratio in noisy urban environments and the results are compared with the direct current (DC) calibration to avoid possible effects due to eddy current. In our experiment, a calibration relative error of about 6.89 × 10-4 is obtained, and the error is mainly caused by the non-orthogonality of three axes of the Helmholtz coils. The method does not need precise alignment of the magnetometer inside the Helmholtz coil. It can be used for the multichannel magnetometer system calibration effectively and accurately. Project supported by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences (Grant No. XDB04020200) and the Shanghai Municipal Science and Technology Commission Project, China (Grant No. 15DZ1940902).

  1. Crystal timing offset calibration method for time of flight PET scanners

    Science.gov (United States)

    Ye, Jinghan; Song, Xiyun

    2016-03-01

    In time-of-flight (TOF) positron emission tomography (PET), precise calibration of the timing offset of each crystal of a PET scanner is essential. Conventionally this calibration requires a specially designed tool just for this purpose. In this study a method that uses a planar source to measure the crystal timing offsets (CTO) is developed. The method uses list mode acquisitions of a planar source placed at multiple orientations inside the PET scanner field-of-view (FOV). The placement of the planar source in each acquisition is automatically figured out from the measured data, so that a fixture for exactly placing the source is not required. The expected coincidence time difference for each detected list mode event can be found from the planar source placement and the detector geometry. A deviation of the measured time difference from the expected one is due to CTO of the two crystals. The least squared solution of the CTO is found iteratively using the list mode events. The effectiveness of the crystal timing calibration method is evidenced using phantom images generated by placing back each list mode event into the image space with the timing offset applied to each event. The zigzagged outlines of the phantoms in the images become smooth after the crystal timing calibration is applied. In conclusion, a crystal timing calibration method is developed. The method uses multiple list mode acquisitions of a planar source to find the least squared solution of crystal timing offsets.

  2. Application of Taguchi Method and Genetic Algorithm for Calibration of Soil Constitutive Models

    Directory of Open Access Journals (Sweden)

    M. Yazdani

    2013-01-01

    Full Text Available A special inverse analysis method is established in order to calibrate soil constitutive models. Taguchi method as a systematic sensitivity analysis is conducted to determine the real values of mechanical parameters. This technique was applied on the hardening soil (as an elastoplastic constitutive model which is calibrated using the results from pressuremeter test performed on “Le Rheu” clayey sand. Meanwhile, a genetic algorithm (GA as a well-known optimization technique is used to fit the computed numerical results and observed data of the soil model. This study indicates that the Taguchi method can reasonably calibrate the soil parameters with minimum number of numerical analyses in comparison with GA which needs plenty of analyses. In addition, the contribution of each parameter on mechanical behavior of soil during the test can be determined through the Taguchi method.

  3. New Methods for Kinematic Modelling and Calibration of Robots

    DEFF Research Database (Denmark)

    Søe-Knudsen, Rune

    2014-01-01

    Improving a robot's accuracy increases its ability to solve certain tasks, and is therefore valuable. Practical ways of achieving this improved accuracy, even after robot repair, is also valuable. In this work, we introduce methods that improve the robot's accuracy and make it possible to maintai...... is our contribution to push the boundaries of user-friendly maintenance of industrial robots without expensive equipment....

  4. A GPS-Based Pitot-Static Calibration Method Using Global Output-Error Optimization

    Science.gov (United States)

    Foster, John V.; Cunningham, Kevin

    2010-01-01

    Pressure-based airspeed and altitude measurements for aircraft typically require calibration of the installed system to account for pressure sensing errors such as those due to local flow field effects. In some cases, calibration is used to meet requirements such as those specified in Federal Aviation Regulation Part 25. Several methods are used for in-flight pitot-static calibration including tower fly-by, pacer aircraft, and trailing cone methods. In the 1990 s, the introduction of satellite-based positioning systems to the civilian market enabled new inflight calibration methods based on accurate ground speed measurements provided by Global Positioning Systems (GPS). Use of GPS for airspeed calibration has many advantages such as accuracy, ease of portability (e.g. hand-held) and the flexibility of operating in airspace without the limitations of test range boundaries or ground telemetry support. The current research was motivated by the need for a rapid and statistically accurate method for in-flight calibration of pitot-static systems for remotely piloted, dynamically-scaled research aircraft. Current calibration methods were deemed not practical for this application because of confined test range size and limited flight time available for each sortie. A method was developed that uses high data rate measurements of static and total pressure, and GPSbased ground speed measurements to compute the pressure errors over a range of airspeed. The novel application of this approach is the use of system identification methods that rapidly compute optimal pressure error models with defined confidence intervals in nearreal time. This method has been demonstrated in flight tests and has shown 2- bounds of approximately 0.2 kts with an order of magnitude reduction in test time over other methods. As part of this experiment, a unique database of wind measurements was acquired concurrently with the flight experiments, for the purpose of experimental validation of the

  5. A quantitative model for heat pulse propagation across large helical device plasmas

    Science.gov (United States)

    Zhu, H.; Dendy, R. O.; Chapman, S. C.; Inagaki, S.

    2015-06-01

    It is known that rapid edge cooling of magnetically confined plasmas can trigger heat pulses that propagate rapidly inward. These can result in large excursion, either positive or negative, in the electron temperature at the core. A set of particularly detailed measurements was obtained in Large Helical Device (LHD) plasmas [S. Inagaki et al., Plasma Phys. Controlled Fusion 52, 075002 (2010)], which are considered here. By applying a travelling wave transformation, we extend the model of Dendy et al., Plasma Phys. Controlled Fusion 55, 115009 (2013), which successfully describes the local time-evolution of heat pulses in these plasmas, to include also spatial dependence. The new extended model comprises two coupled nonlinear first order differential equations for the (x, t) evolution of the deviation from steady state of two independent variables: the excess electron temperature gradient and the excess heat flux, both of which are measured in the LHD experiments. The mathematical structure of the model equations implies a formula for the pulse velocity, defined in terms of plasma quantities, which aligns with empirical expectations and is within a factor of two of the measured values. We thus model spatio-temporal pulse evolution, from first principles, in a way which yields as output the spatiotemporal evolution of the electron temperature, which is also measured in detail in the experiments. We compare the model results against LHD datasets using appropriate initial and boundary conditions. Sensitivity of this nonlinear model with respect to plasma parameters, initial conditions, and boundary conditions is also investigated. We conclude that this model is able to match experimental data for the spatio-temporal evolution of the temperature profiles of these pulses, and their propagation velocities, across a broad radial range from r /a ≃0.5 to the plasma core. The model further implies that the heat pulse may be related mathematically to soliton solutions of the

  6. A robust method for online stereo camera self-calibration in unmanned vehicle system

    Science.gov (United States)

    Zhao, Yu; Chihara, Nobuhiro; Guo, Tao; Kimura, Nobutaka

    2014-06-01

    Self-calibration is a fundamental technology used to estimate the relative posture of the cameras for environment recognition in unmanned system. We focused on the issue of recognition accuracy decrease caused by the vibration of platform and conducted this research to achieve on-line self-calibration using feature point's registration and robust estimation of fundamental matrix. Three key factors in this respect are needed to be improved. Firstly, the feature mismatching exists resulting in the decrease of estimation accuracy of relative posture. The second, the conventional estimation method cannot satisfy both the estimation speed and calibration accuracy at the same tame. The third, some system intrinsic noises also lead greatly to the deviation of estimation results. In order to improve the calibration accuracy, estimation speed and system robustness for the practical implementation, we discuss and analyze the algorithms to make improvements on the stereo camera system to achieve on-line self-calibration. Based on the epipolar geometry and 3D images parallax, two geometry constraints are proposed to make the corresponding feature points search performed in a small search-range resulting in the improvement of matching accuracy and searching speed. Then, two conventional estimation algorithms are analyzed and evaluated for estimation accuracy and robustness. The third, Rigorous posture calculation method is proposed with consideration of the relative posture deviation of each separated parts in the stereo camera system. Validation experiments were performed with the stereo camera mounted on the Pen-Tilt Unit for accurate rotation control and the evaluation shows that our proposed method is fast and of high accuracy with high robustness for on-line self-calibration algorithm. Thus, as the main contribution, we proposed methods to solve the on-line self-calibration fast and accurately, envision the possibility for practical implementation on unmanned system as

  7. Shrinkage calibration method for μPIM manufactured parts

    DEFF Research Database (Denmark)

    Quagliotti, Danilo; Tosello, Guido; Salaga, J.;

    2016-01-01

    were compared with the sintered parts (final products) calculating the percentage of shrinkage after sintering. Successively, the expanded uncertainty of the measured dimensions were evaluated for each single part as well as for the overall parts. Finally, the estimated uncertainty for the shrinkage...... was evaluated propagating the expanded uncertainty previously stated and considering green and sintered parts correlated. Results showed that the proposed method can be effective instating tolerances if it is assumed that the variability on the dimensions induced by the shrinkage equals the propagated...

  8. A simple method for wind tunnel balance calibration including non-linear interaction terms

    Science.gov (United States)

    Ramaswamy, M. A.; Srinivas, T.; Holla, V. S.

    The conventional method for calibrating wind tunnel balances to obtain the coupled linear and nonlinear interaction terms requires the application of combinations of pure components of the loads on the calibration body compensating the deflection of the balance. For a six-component balance, this calls for a complex loading system and an arrangement to translate and tilt the balance support about all three axes. A simple method called the least-square method is illustrated for a three-component balance. The simplicity arises from the fact that application of the pure components of the loads or reorientation of the balance is not required. A single load is applied that has various components whose magnitudes can be easily found knowing the orientation of the calibration body under load and the point of application of the load. The coefficients are obtained by using the least-square-fit approach to match the outputs obtained for various combinations of load.

  9. Rotated-Random-Scanning: a simple method for set-valued model calibration

    NARCIS (Netherlands)

    Janssen PHM; Heuberger PSC; CWM

    1995-01-01

    A simple method is proposed for calibrating models in ill-defined and information-poor situations, which are frequently encountered in environmental applications. The method performs an efficient scan of the parameter space, based on Monte Carlo sampling in cobination with rotations. Software has be

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

    Science.gov (United States)

    Sun, Ting; Xing, Fei; You, Zheng

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Zheng You

    2013-04-01

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

  12. Hybrid calibration method for six-component force/torque transducers of wind tunnel balance based on support vector machines

    Institute of Scientific and Technical Information of China (English)

    Ma Yingkun; Xie Shilin; Zhang Xinong; Luo Yajun

    2013-01-01

    A hybrid calibration approach based on support vector machines (SVM) is proposed to characterize nonlinear cross coupling of multi-dimensional transducer.It is difficult to identify these unknown nonlinearities and crosstalk just with a single conventional calibration approach.In this paper,a hybrid model comprising calibration matrix and SVM model for calibrating linearity and nonlinearity respectively is built up.The calibration matrix is determined by linear artificial neural network (ANN),and the SVM is used to compensate for the nonlinear cross coupling among each dimension.A simulation of the calibration of a multi-dimensional sensor is conducted by the SVM hybrid calibration method,which is then utilized to calibrate a six-component force/torque transducer of wind tunnel balance.From the calibrating results,it can be indicated that the SVM hybrid calibration method has improved the calibration accuracy significantly without increasing data samples,compared with calibration matrix.Moreover,with the calibration matrix,the hybrid model can provide a basis for the design of transducers.

  13. The Three-Transponder Method: A Novel Approach for Traceable (E)RCS Calibration of SAR Transponders

    OpenAIRE

    Björn J. Döring; Reimann, Jens; Raab, Sebastian; Jirousek, Matthias; Rudolf, Daniel; Schwerdt, Marco

    2016-01-01

    The radiometric calibration of synthetic aperture radar (SAR) systems is typically based on the known backscatter of calibration point targets such as transponders. Before a SAR calibration campaign can begin it is therefore necessary to determine the backscatter (radar cross section or RCS) of the transponder itself. Known methods suffer from unnecessarily high uncertainty contributions and therefore also affect the radiometric uncertainty of the calibrated SAR system. In this paper we prese...

  14. Calibration Method for Confocal X-Ray Microanalysis with Polychromatic Excitation

    Directory of Open Access Journals (Sweden)

    C. Sosa

    2015-01-01

    Full Text Available To apply the fundamental parameters method at the confocal setup the knowledge of the sensitivity of the spectrometer is required which depends on the characteristics of two X-ray lenses: one in the excitation channel and another in the detection channel. For the particular case of polychromatic excitation, the theory shows that the focalization properties of the excitation lens for all incident energies affect the X-ray fluorescence intensity. Therefore the traditional calibration method based on the measurement of standard samples becomes unstable since the number of required fitting parameters is too high. To reduce these parameters a previous characterization of the excitation lens by a simulation program was employed giving rise to a simplified confocal setup calibration. The developed calibration method was applied for a confocal spectrometer implemented in the Brazilian Synchrotron Radiation Source (LNLS with white beam. The experimental parameters of the sensitivity were obtained from depth profile analysis of several pure thin films. The calibrated confocal setup was used to quantify reference standards in order to validate the calibration procedure. Our results for elemental concentrations show relative errors less than 15% for the quantitative analysis of a light matrix reference standard.

  15. Standardization of Laser Methods and Techniques for Vibration Measurements and Calibrations

    Science.gov (United States)

    von Martens, Hans-Jürgen

    2010-05-01

    The realization and dissemination of the SI units of motion quantities (vibration and shock) have been based on laser interferometer methods specified in international documentary standards. New and refined laser methods and techniques developed by national metrology institutes and by leading manufacturers in the past two decades have been swiftly specified as standard methods for inclusion into in the series ISO 16063 of international documentary standards. A survey of ISO Standards for the calibration of vibration and shock transducers demonstrates the extended ranges and improved accuracy (measurement uncertainty) of laser methods and techniques for vibration and shock measurements and calibrations. The first standard for the calibration of laser vibrometers by laser interferometry or by a reference accelerometer calibrated by laser interferometry (ISO 16063-41) is on the stage of a Draft International Standard (DIS) and may be issued by the end of 2010. The standard methods with refined techniques proved to achieve wider measurement ranges and smaller measurement uncertainties than that specified in the ISO Standards. The applicability of different standardized interferometer methods to vibrations at high frequencies was recently demonstrated up to 347 kHz (acceleration amplitudes up to 350 km/s2). The relative deviations between the amplitude measurement results of the different interferometer methods that were applied simultaneously, differed by less than 1% in all cases.

  16. Method for pan-tilt camera calibration using single control point.

    Science.gov (United States)

    Li, Yunting; Zhang, Jun; Hu, Wenwen; Tian, Jinwen

    2015-01-01

    The pan-tilt (PT) camera is widely used in video surveillance systems due to its rotatable property and low cost. The rough output of a PT camera may not satisfy the demand of practical applications; hence an accurate calibration method of a PT camera is desired. However, high-precision camera calibration methods usually require sufficient control points not guaranteed in some practical cases of a PT camera. In this paper, we present a novel method to online calibrate the rotation angles of a PT camera by using only one control point. This is achieved by assuming that the intrinsic parameters and position of the camera are known in advance. More specifically, we first build a nonlinear PT camera model with respect to two parameters Pan and Tilt. We then convert the nonlinear model into a linear model according to sine and cosine of Tilt, where each element in the augmented coefficient matrix is a function of the single variable Pan. A closed-form solution of Pan and Tilt can then be derived by solving a quadratic equation of tangent of Pan. Our method is noniterative and does not need features matching; thus its time efficiency is better. We evaluate our calibration method on various synthetic and real data. The quantitative results demonstrate that the proposed method outperforms other state-of-the-art methods if the intrinsic parameters and position of the camera are known in advance.

  17. 光电综合标校系统光轴平行度标校方法%Optical Parallelism Calibration Method of Photoelectric Integrated Calibration System

    Institute of Scientific and Technical Information of China (English)

    郑均杰; 张镭; 李杰然

    2011-01-01

    针对光电综合标校系统的功能组成及标校原理,提出了标校靶标的设计及标校方法,并利用感光相纸对激光光斑进行聚焦采集,实现了对电视/红外/激光三者光轴一致性的标校,检测结果验证了该标校靶标及标校方法的可行性和有效性。%Aiming at the function component and calibration principle of photoelectric integrated calibration system,this paper presents the design and calibration method of calibration drone,and realizes the calibration to the axes consistency of television,infrared and laser by using the photographic papers to focus and collect laser spots.The detection result proves the feasibility and usefulness of the calibration drone and the calibration method.

  18. 利用热脉冲技术测量土壤表层含水率%Measuring soil water content in surface layer with heat-pulse technique

    Institute of Scientific and Technical Information of China (English)

    张晓; 王月月; 任图生

    2015-01-01

    Accurate measurement of near-surface soil water content (0-5 cm) is essential for studying water and heat exchange between land and atmosphere. Heat-pulse technique has potential to measure soil volumetric water content, but only used in laboratory, greenhouse and field at depths below 5 cm. The objective of this study was to test the possibility of heat-pulse technique for measuring water content in near-surface soil layer (0-5 cm) in the field. The experiment was conducted in a sandy loam soil in an experimental plot (2 m×2 m×2 m) in China Agricultural University. Multi-needle heat-pulse sensor was used to measure volumetric heat capacity in various depths above 5 cm and four multi-needle heat-pulse sensors were used. Average volumetric heat capacity from four multi-needle heat-pulse sensors was calculated at each depth and the values at four depths (3, 9, 21 and 39 mm) were extracted to be analyzed. When calculating soil volumetric heat capacity from temperature change versus time data, the pulse infinite line source theory was used at 9, 21 and 39 mm, while for volumetric heat capacity at 3 mm, the pulse infinite line source-adiabatic boundary condition was used because of the soil-air interface effect. Based on the linear relationship of soil volumetric heat capacity and volumetric water content in mineral soil, soil volumetric water content could be calculated from soil volumetric heat capacity, volumetric heat capacity of water, soil bulk density and solid heat capacity, which was named heat-pulse water content method. When the temporal series of soil volumetric heat capacity were measured, the change in soil water content could be calculated without knowledge of soil-specific properties. With the initial water content measured by another independent method, dynamic of soil water content could be determined from the change in soil water content series data and this method was called heat-pulse water content change method. Water contents at those four

  19. New method for computer numerical control machine tool calibration: Relay method

    Institute of Scientific and Technical Information of China (English)

    LIU Huanlao; SHI Hanming; LI Bin; ZHOU Huichen

    2007-01-01

    Relay measurement method,which uses the kilogram-meter (KGM) measurement system to identify volumetric errors on the planes of computer numerical con trol (CNC) machine tools,is verified through experimental tests.During the process,all position errors on the entire plane table are measured by the equipment,which is limited to a small field.All errors are obtained first by measuring the error of the basic position near the original point.On the basis of that positional error,the positional errors far away from the original point are measured.Using this analogy,the error information on the positional points on the entire plane can be obtained.The process outlined above is called the relay meth od.Test results indicate that the accuracy and repeatability are high,and the method can be used to calibrate geometric errors on the plane of CNC machine tools after backlash errors have been well compensated.

  20. Calibration method for a vision guiding-based laser-tracking measurement system

    Science.gov (United States)

    Shao, Mingwei; Wei, Zhenzhong; Hu, Mengjie; Zhang, Guangjun

    2015-08-01

    Laser-tracking measurement systems (laser trackers) based on a vision-guiding device are widely used in industrial fields, and their calibration is important. As conventional methods typically have many disadvantages, such as difficult machining of the target and overdependence on the retroreflector, a novel calibration method is presented in this paper. The retroreflector, which is necessary in the normal calibration method, is unnecessary in our approach. As the laser beam is linear, points on the beam can be obtained with the help of a normal planar target. In this way, we can determine the function of a laser beam under the camera coordinate system, while its corresponding function under the laser-tracker coordinate system can be obtained from the encoder of the laser tracker. Clearly, when several groups of functions are confirmed, the rotation matrix can be solved from the direction vectors of the laser beams in different coordinate systems. As the intersection of the laser beams is the origin of the laser-tracker coordinate system, the translation matrix can also be determined. Our proposed method not only achieves the calibration of a single laser-tracking measurement system but also provides a reference for the calibration of a multistation system. Simulations to evaluate the effects of some critical factors were conducted. These simulations show the robustness and accuracy of our method. In real experiments, the root mean square error of the calibration result reached 1.46 mm within a range of 10 m, even though the vision-guiding device focuses on a point approximately 5 m away from the origin of its coordinate system, with a field of view of approximately 200 mm  ×  200 mm.

  1. Calibration method for a vision guiding-based laser-tracking measurement system

    International Nuclear Information System (INIS)

    Laser-tracking measurement systems (laser trackers) based on a vision-guiding device are widely used in industrial fields, and their calibration is important. As conventional methods typically have many disadvantages, such as difficult machining of the target and overdependence on the retroreflector, a novel calibration method is presented in this paper. The retroreflector, which is necessary in the normal calibration method, is unnecessary in our approach. As the laser beam is linear, points on the beam can be obtained with the help of a normal planar target. In this way, we can determine the function of a laser beam under the camera coordinate system, while its corresponding function under the laser-tracker coordinate system can be obtained from the encoder of the laser tracker. Clearly, when several groups of functions are confirmed, the rotation matrix can be solved from the direction vectors of the laser beams in different coordinate systems. As the intersection of the laser beams is the origin of the laser-tracker coordinate system, the translation matrix can also be determined. Our proposed method not only achieves the calibration of a single laser-tracking measurement system but also provides a reference for the calibration of a multistation system. Simulations to evaluate the effects of some critical factors were conducted. These simulations show the robustness and accuracy of our method. In real experiments, the root mean square error of the calibration result reached 1.46 mm within a range of 10 m, even though the vision-guiding device focuses on a point approximately 5 m away from the origin of its coordinate system, with a field of view of approximately 200 mm  ×  200 mm. (paper)

  2. A geometric calibration method for inverse geometry computed tomography using P-matrices

    Science.gov (United States)

    Slagowski, Jordan M.; Dunkerley, David A. P.; Hatt, Charles R.; Speidel, Michael A.

    2016-03-01

    Accurate and artifact free reconstruction of tomographic images requires precise knowledge of the imaging system geometry. This work proposes a novel projection matrix (P-matrix) based calibration method to enable C-arm inverse geometry CT (IGCT). The method is evaluated for scanning-beam digital x-ray (SBDX), a C-arm mounted inverse geometry fluoroscopic technology. A helical configuration of fiducials is imaged at each gantry angle in a rotational acquisition. For each gantry angle, digital tomosynthesis is performed at multiple planes and a composite image analogous to a cone-beam projection is generated from the plane stack. The geometry of the C-arm, source array, and detector array is determined at each angle by constructing a parameterized 3D-to-2D projection matrix that minimizes the sum-of-squared deviations between measured and projected fiducial coordinates. Simulations were used to evaluate calibration performance with translations and rotations of the source and detector. In a geometry with 1 mm translation of the central ray relative to the axis-of-rotation and 1 degree yaw of the detector and source arrays, the maximum error in the recovered translational parameters was 0.4 mm and maximum error in the rotation parameter was 0.02 degrees. The relative rootmean- square error in a reconstruction of a numerical thorax phantom was 0.4% using the calibration method, versus 7.7% without calibration. Changes in source-detector-distance were the most challenging to estimate. Reconstruction of experimental SBDX data using the proposed method eliminated double contour artifacts present in a non-calibrated reconstruction. The proposed IGCT geometric calibration method reduces image artifacts when uncertainties exist in system geometry.

  3. Respiratory inductance plethysmography in healthy infants: a comparison of three calibration methods.

    Science.gov (United States)

    Poole, K A; Thompson, J R; Hallinan, H M; Beardsmore, C S

    2000-12-01

    Respiratory inductance plethysmography (RIP) measures respiration from body surface movements. Various techniques have been proposed for calibration in order that RIP may be used quantitatively. These include calculation of the proportionality constant of ribcage to abdominal volume change (K). The aims of this study were to 1) establish whether a fixed value of K could be used for calibration, and 2) compare this technique with multiple linear regression (MLR) and qualitative diagnostic calibration (QDC) in normal healthy infants. Recordings of pneumotachograph (PNT) flow and RIP were made during quiet (QS) and active sleep (AS) in 12 infants. The first 5 min in a sleep state were used to calculate calibration factors, which were applied to subsequent validation data. The absolute percentage error between RIP and PNT tidal volumes was calculated. The percentage error was similar over a wide range of K during QS. However, K became more critical when breathing was out of phase. A standard for K of 0.5 was chosen. There was good agreement between calibration methods during QS and AS. In the first minute following calibration during QS, the mean absolute errors were 3.5, 4.1 and 5.3% for MLR, QDC and fixed K respectively. The equivalent errors in AS were 11.5, 13.1 and 13.7% respectively. The simple fixed ratio method can be used to measure tidal volume with similar accuracy to multiple linear regression and qualitative diagnostic calibration in healthy unsedated sleeping infants, although it remains to be validated in other groups of infants, such as those with respiratory disease.

  4. PMT response drift of ATLAS Tile Laser II calibration system: an introduction of a new method

    CERN Document Server

    Di Gregorio, Giulia

    2016-01-01

    In this article I describe the performance of the monitoring diodes of the Laser II system, a new system for run II used to calibrate the gain variation of PMTs in between two cesium scan. I also show a new method to measure the PMT drift response that it is compared to the method used up to now (Clermont-Ferrant) corrected with the Pisa method. The agreement between the two method is within 0.2%.

  5. CEILINEX 2015: Validation of calibration methods during the ceilometer inter-comparison

    Science.gov (United States)

    Hervo, Maxime

    2016-04-01

    In Europe, more than 700 ceilometers are measuring continuously. These instruments can be used for many applications such as detection of cloud base and aerosol layers height, aerosol profiling or for fog now-casting. However, from different manufacturers exist and the results can vary extensively from one type to another. During the CeiLinEx2015 campaign (Ceilometer Performance Experiment at Lindenberg 2015), 6 types of ceilometers (CL31, CL51, CHM15k, CHM15kx CS135 and LD40) were measuring simultaneously at Lindenberg (Germany) from June to September 2015. Each type was represented by two instruments in order to assess the instrument-to-instrument variability. A companion contribution by Mattis et al. presents an overview of the campaign. The monitoring of the temporal and spatial evolution of aerosol layers like the volcanic ash, is crucial to compare measurements from different sites. Therefore, all instruments need to be calibrated in order to provide consistent results. This contribution will focus on the validation and the comparison of state-of-the-art calibration methods. The calibration methods tested were are the cloud calibration (O'Connor et al., 2004) and the Rayleigh calibration Method (Wiegner and Geiß, 2012). Both methods can be applied without on-site intervention and are thus suitable for automatic networks. Operational automated algorithms based on these methods were developed in the framework of the TOPROF project (ESSEM COST Action ES1303)..The Cloud calibration was found more appropriate for analog instruments with analog signal detection measuring at around 905nm (Vaisala CL51 and CL31 and Campbell Scientific CS135). The Rayleigh was more suitable for photon-counting systems measuring at 1064nm (CHM15k, CHM15kx). For the first time, these methods were tested simultaneously on different instrument types and compared amongst each other. For a dust event occurred on the 13/08/2015, the attenuated backscatter coefficient difference amongst all

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

    CERN Document Server

    Hong, Ran; Bagdasarova, Yelena; Flechard, Xavier; Garcia, Alejandro; Mueller, Peter; Knecht, Andreas; Lienard, Etienne; Kossin, Michael; Sternberg, Matthew G; Swanson, H E; Zumwalt, David W

    2016-01-01

    We have developed a position response calibration method for a micro-channel plate (MCP) detector with a delay-line anode position readout scheme. Using an {\\em in situ} calibration mask, an accuracy of 8~$\\mu$m and a resolution of 85~$\\mu$m (FWHM) have been achieved for MeV-scale $\\alpha$ particles and ions with energies of $\\sim$10~keV. For high statistics experiments, this method can be directly employed with the experimental data without any dedicated calibration runs. The improved performance of the MCP detector can find applications in many fields of AMO and nuclear physics. In our case, it helps reducing systematic uncertainties in a high-precision nuclear $\\beta$-decay experiment.

  7. Calibration-free inverse method for depth-profile analysis with laser-induced breakdown spectroscopy

    Science.gov (United States)

    Gaudiuso, R.

    2016-09-01

    The Calibration-free inverse method (CF-IM) is a variant of the classical CF approach that can be used for the determination of the plasma temperature using a single calibration standard. In this work, the IM was suitably modified in order to test its applicability to the depth-resolved elemental analyses of stratified samples. The single calibration standard was used as a sort of reference sample to model the acquisition conditions of the spectra, to investigate the effect of the acquisition geometry, and to account for possible crater-induced changes in the acquired spectra and plasma parameters. Thus, a depth profile of the standard sample was performed in order to obtain a plasma temperature profile, which in turn was employed, together with the experimental electron density profile, for the depth profile calibration-free analysis. The methodology was also applied to archaeological samples, with the purpose of testing the method with weathered and layered samples, and compared with the results of classical LIBS with calibration lines.

  8. An Improved Calibration Method for Hydrazine Monitors for the United States Air Force

    Energy Technology Data Exchange (ETDEWEB)

    Korsah, K

    2003-07-07

    This report documents the results of Phase 1 of the ''Air Force Hydrazine Detector Characterization and Calibration Project''. A method for calibrating model MDA 7100 hydrazine detectors in the United States Air Force (AF) inventory has been developed. The calibration system consists of a Kintek 491 reference gas generation system, a humidifier/mixer system which combines the dry reference hydrazine gas with humidified diluent or carrier gas to generate the required humidified reference for calibrations, and a gas sampling interface. The Kintek reference gas generation system itself is periodically calibrated using an ORNL-constructed coulometric titration system to verify the hydrazine concentration of the sample atmosphere in the interface module. The Kintek reference gas is then used to calibrate the hydrazine monitors. Thus, coulometric titration is only used to periodically assess the performance of the Kintek reference gas generation system, and is not required for hydrazine monitor calibrations. One advantage of using coulometric titration for verifying the concentration of the reference gas is that it is a primary standard (if used for simple solutions), thereby guaranteeing, in principle, that measurements will be traceable to SI units (i.e., to the mole). The effect of humidity of the reference gas was characterized by using the results of concentrations determined by coulometric titration to develop a humidity correction graph for the Kintek 491 reference gas generation system. Using this calibration method, calibration uncertainty has been reduced by 50% compared to the current method used to calibrate hydrazine monitors in the Air Force inventory and calibration time has also been reduced by more than 20%. Significant findings from studies documented in this report are the following: (1) The Kintek 491 reference gas generation system (generator, humidifier and interface module) can be used to calibrate hydrazine detectors. (2) The

  9. An alternative method for calibration of narrow band radiometer using a radiative transfer model

    Energy Technology Data Exchange (ETDEWEB)

    Salvador, J; Wolfram, E; D' Elia, R [Centro de Investigaciones en Laseres y Aplicaciones, CEILAP (CITEFA-CONICET), Juan B. de La Salle 4397 (B1603ALO), Villa Martelli, Buenos Aires (Argentina); Zamorano, F; Casiccia, C [Laboratorio de Ozono y Radiacion UV, Universidad de Magallanes, Punta Arenas (Chile) (Chile); Rosales, A [Universidad Nacional de la Patagonia San Juan Bosco, UNPSJB, Facultad de Ingenieria, Trelew (Argentina) (Argentina); Quel, E, E-mail: jsalvador@citefa.gov.ar [Universidad Nacional de la Patagonia Austral, Unidad Academica Rio Gallegos Avda. Lisandro de la Torre 1070 ciudad de Rio Gallegos-Sta Cruz (Argentina) (Argentina)

    2011-01-01

    The continual monitoring of solar UV radiation is one of the major objectives proposed by many atmosphere research groups. The purpose of this task is to determine the status and degree of progress over time of the anthropogenic composition perturbation of the atmosphere. Such changes affect the intensity of the UV solar radiation transmitted through the atmosphere that then interacts with living organisms and all materials, causing serious consequences in terms of human health and durability of materials that interact with this radiation. One of the many challenges that need to be faced to perform these measurements correctly is the maintenance of periodic calibrations of these instruments. Otherwise, damage caused by the UV radiation received will render any one calibration useless after the passage of some time. This requirement makes the usage of these instruments unattractive, and the lack of frequent calibration may lead to the loss of large amounts of acquired data. Motivated by this need to maintain calibration or, at least, know the degree of stability of instrumental behavior, we have developed a calibration methodology that uses the potential of radiative transfer models to model solar radiation with 5% accuracy or better relative to actual conditions. Voltage values in each radiometer channel involved in the calibration process are carefully selected from clear sky data. Thus, tables are constructed with voltage values corresponding to various atmospheric conditions for a given solar zenith angle. Then we model with a radiative transfer model using the same conditions as for the measurements to assemble sets of values for each zenith angle. The ratio of each group (measured and modeled) allows us to calculate the calibration coefficient value as a function of zenith angle as well as the cosine response presented by the radiometer. The calibration results obtained by this method were compared with those obtained with a Brewer MKIII SN 80 located in the

  10. An alternative method for calibration of narrow band radiometer using a radiative transfer model

    International Nuclear Information System (INIS)

    The continual monitoring of solar UV radiation is one of the major objectives proposed by many atmosphere research groups. The purpose of this task is to determine the status and degree of progress over time of the anthropogenic composition perturbation of the atmosphere. Such changes affect the intensity of the UV solar radiation transmitted through the atmosphere that then interacts with living organisms and all materials, causing serious consequences in terms of human health and durability of materials that interact with this radiation. One of the many challenges that need to be faced to perform these measurements correctly is the maintenance of periodic calibrations of these instruments. Otherwise, damage caused by the UV radiation received will render any one calibration useless after the passage of some time. This requirement makes the usage of these instruments unattractive, and the lack of frequent calibration may lead to the loss of large amounts of acquired data. Motivated by this need to maintain calibration or, at least, know the degree of stability of instrumental behavior, we have developed a calibration methodology that uses the potential of radiative transfer models to model solar radiation with 5% accuracy or better relative to actual conditions. Voltage values in each radiometer channel involved in the calibration process are carefully selected from clear sky data. Thus, tables are constructed with voltage values corresponding to various atmospheric conditions for a given solar zenith angle. Then we model with a radiative transfer model using the same conditions as for the measurements to assemble sets of values for each zenith angle. The ratio of each group (measured and modeled) allows us to calculate the calibration coefficient value as a function of zenith angle as well as the cosine response presented by the radiometer. The calibration results obtained by this method were compared with those obtained with a Brewer MKIII SN 80 located in the

  11. Precision calibration method for binocular vision measurement systems based on arbitrary translations and 3D-connection information

    Science.gov (United States)

    Yang, Jinghao; Jia, Zhenyuan; Liu, Wei; Fan, Chaonan; Xu, Pengtao; Wang, Fuji; Liu, Yang

    2016-10-01

    Binocular vision systems play an important role in computer vision, and high-precision system calibration is a necessary and indispensable process. In this paper, an improved calibration method for binocular stereo vision measurement systems based on arbitrary translations and 3D-connection information is proposed. First, a new method for calibrating the intrinsic parameters of binocular vision system based on two translations with an arbitrary angle difference is presented, which reduces the effect of the deviation of the motion actuator on calibration accuracy. This method is simpler and more accurate than existing active-vision calibration methods and can provide a better initial value for the determination of extrinsic parameters. Second, a 3D-connection calibration and optimization method is developed that links the information of the calibration target in different positions, further improving the accuracy of the system calibration. Calibration experiments show that the calibration error can be reduced to 0.09%, outperforming traditional methods for the experiments of this study.

  12. Calibration Tests of a Sonotrode and Cavitation Erosion Research through Indirect Cavitation Method for a Steel

    Directory of Open Access Journals (Sweden)

    Marian-Dumitru Nedeloni

    2012-09-01

    Full Text Available This paper content the describe of cavitation erosion stand, especially the ultrasonic generator; the calibration tests of a oxidable steel sonotrode and the experimental results for a specimen also from oxidable steel material tested at cavitation erosion through the indirect cavitation method.

  13. A C-arm calibration method with application to fluoroscopic image-guided procedures

    Science.gov (United States)

    Rai, Lav; Gibbs, Jason D.; Wibowo, Henky

    2012-02-01

    C-arm fluoroscopy units provide continuously updating X-ray video images during surgical procedure. The modality is widely adopted for its low cost, real-time imaging capabilities, and its ability to display radio-opaque tools in the anatomy. It is, however, important to correct for fluoroscopic image distortion and estimate camera parameters, such as focal length and camera center, for registration with 3D CT scans in fluoroscopic imageguided procedures. This paper describes a method for C-arm calibration and evaluates its accuracy in multiple C-arm units and in different viewing orientations. The proposed calibration method employs a commerciallyavailable unit to track the C-arm and a calibration plate. The method estimates both the internal calibration parameters and the transformation between the coordinate systems of tracker and C-arm. The method was successfully tested on two C-arm units (GE OEC 9800 and GE OEC 9800 Plus) of different image intensifier sizes and verified with a rigid airway phantom model. The mean distortion-model error was found to be 0.14 mm and 0.17 mm for the respective C-arms. The mean overall system reprojection error (which measures the accuracy of predicting an image using tracker coordinates) was found to be 0.63 mm for the GE OEC 9800.

  14. A simple method for energy calibration of heavy-ion beams

    NARCIS (Netherlands)

    Evers, E.J.; Vries, J.W.; Engelbertink, G.A.P.; Leun, C. van der

    1987-01-01

    A method is described for the calibration of analyzing-magnet systems of heavy-ion accelerators. It makes use of resonances in inverse (p, αγ) reactions, i.e. with heavy-ion beams on hydrogen targets. Instead of a gas target we use the very thin hydrogen-containing surface layer on a gold foil, whic

  15. A novel single-step, multipoint calibration method for instrumented Lab-on-Chip systems

    DEFF Research Database (Denmark)

    Pfreundt, Andrea; Patou, François; Zulfiqar, Azeem;

    2014-01-01

    . The pitfalls of PoC system adoption can be addressed early in the system design phase. They require a multidisciplinary design approach supported by systems engineering tools and methods. Considering this, we here present both a model and an implementation of a simple and rapid calibration scheme...... specifically addresses the important interfaces between a novel microfluidic unit to integrate the sensor array and a mobile-device hardware accessory. A multi-point calibration curve is obtained by generating a defined set of reference concentrations from a single input. By consecutively splitting the flow...

  16. Energy Calibration of the BaBar EMC Using the Pi0 Invariant Mass Method

    Energy Technology Data Exchange (ETDEWEB)

    Tanner, David J.; /Manchester U.

    2007-04-06

    The BaBar electromagnetic calorimeter energy calibration method was compared with the local and global peak iteration procedures, of Crystal Barrel and CLEO-II. An investigation was made of the possibility of {Upsilon}(4S) background reduction which could lead to increased statistics over a shorter time interval, for efficient calibration runs. The BaBar software package was used with unreconstructed data to study the energy response of the calorimeter, by utilizing the {pi}{sup 0} mass constraint on pairs of photon clusters.

  17. A least squares method for CVT calibration in a RLC capacitor discharge circuit.

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Stephen E.; Dickey, Fred McCartney; Pecak, Sara North

    2003-11-01

    In many applications, the ability to monitor the output of a capacitive discharge circuit is imperative to ensuring the reliability and accuracy of the unit. This monitoring is commonly accomplished with the use of a Current Viewing Transformer (CVT). In order to calibrate the CVT, the circuit is assembled with a Current Viewing Transformer (CVR) in addition to the CVT and the peak outputs compared. However, difficulties encountered with the use of CVRs make it desirable to eliminate the use of the CVR from the calibration process. This report describes a method for determining the calibration factor between the current throughput and the CVT voltage output in a capacitive discharge unit from the CVT ringdown data and values of initial voltage and capacitance of the circuit. Previous linear RLC fitting work for determining R, L, and C is adapted to return values of R, L, and the calibration factor, k. Separate solutions for underdamped and overdamped cases are presented and implemented on real circuit data using MathCad software with positive results. This technique may also offer a unique approach to self calibration of current measuring devices.

  18. Virtual point source efficiency calibration method for voluminous sample of radio-xenon based on efficiency function of point source

    International Nuclear Information System (INIS)

    A virtual point source calibration method is developed to finish the calibration of voluminous sample. We used a mixed point source to get the parameters of efficiency function, obtaining the virtual position of voluminous sample. So, the detection efficiency of xenon samples and standard soil samples were calibrated by placing the point source at their virtual position. The Monte Carlo method was also used to simulate the detector efficiency of xenon samples. Deviations between the virtual source method and Monte Carlo simulation are within 2.2 % for xenon samples. Thus, we have developed two robust efficiency calibration methods based on Monte Carlo simulations and virtual point source, respectively. (author)

  19. A curve fitting method for extrinsic camera calibration from a single image of a cylindrical object

    Science.gov (United States)

    Winkler, A. W.; Zagar, B. G.

    2013-08-01

    An important step in the process of optical steel coil quality assurance is to measure the proportions of width and radius of steel coils as well as the relative position and orientation of the camera. This work attempts to estimate these extrinsic parameters from single images by using the cylindrical coil itself as the calibration target. Therefore, an adaptive least-squares algorithm is applied to fit parametrized curves to the detected true coil outline in the acquisition. The employed model allows for strictly separating the intrinsic and the extrinsic parameters. Thus, the intrinsic camera parameters can be calibrated beforehand using available calibration software. Furthermore, a way to segment the true coil outline in the acquired images is motivated. The proposed optimization method yields highly accurate results and can be generalized even to measure other solids which cannot be characterized by the identification of simple geometric primitives.

  20. Method and apparatus for calibrating multi-axis load cells in a dexterous robot

    Science.gov (United States)

    Wampler, II, Charles W. (Inventor); Platt, Jr., Robert J. (Inventor)

    2012-01-01

    A robotic system includes a dexterous robot having robotic joints, angle sensors adapted for measuring joint angles at a corresponding one of the joints, load cells for measuring a set of strain values imparted to a corresponding one of the load cells during a predetermined pose of the robot, and a host machine. The host machine is electrically connected to the load cells and angle sensors, and receives the joint angle values and strain values during the predetermined pose. The robot presses together mating pairs of load cells to form the poses. The host machine executes an algorithm to process the joint angles and strain values, and from the set of all calibration matrices that minimize error in force balance equations, selects the set of calibration matrices that is closest in a value to a pre-specified value. A method for calibrating the load cells via the algorithm is also provided.

  1. A Field Method for Backscatter Calibration Applied to NOAA's Reson 7125 Multibeam Echo-Sounders

    Science.gov (United States)

    Welton, Briana

    Acoustic seafloor backscatter measurements made by multiple Reson multibeam echo-sounders (MBES) used for hydrographic survey are observed to be inconsistent, affecting the quality of data products and impeding large-scale processing efforts. A method to conduct a relative inter and intea sonar calibration in the field using dual frequency Reson 7125 MBES has been developed, tested, and evaluated to improve the consistency of backscatter measurements made from multiple MBES systems. The approach is unique in that it determines a set of corrections for power, gain, pulse length, and an angle dependent calibration term relative to a single Reson 7125 MBES calibrated in an acoustic test tank. These corrections for each MBES can then be applied during processing for any acquisition setting combination. This approach seeks to reduce the need for subjective and inefficient manual data or data product manipulation during post processing, providing a foundation for improved automated seafloor characterization using data from more than one MBES system.

  2. Dynamic linear calibration method for a wide range neutron flux monitor system in ITER

    International Nuclear Information System (INIS)

    As a key part of the diagnosis system in the International Thermonuclear Experimental Reactor (ITER), the neutron flux monitor (NFM), which measures the neutron intensity of the fusion reaction, is a Counting-Campbelling system with a large dynamic counting range. A dynamic linear calibration method is proposed in this paper to solve the problem of cross-over between the different counting and Campbelling channels, and improve the accuracy of the cross-calibration for long-term operation. The experimental results show that the NFM system with the dynamic linear calibration system can obtain the neutron flux of the fusion reactor in real time and realize the seamless measurement area connection between the two channels. (authors)

  3. Method for array gain and phase uncertainties calibration based on ISM and ESPRIT

    Institute of Scientific and Technical Information of China (English)

    Liao Bin; Liao Guisheng

    2009-01-01

    A now method for array calibration of array gain and phase uncertainties, which severely degrade the performance of spatial spectrum estimation, is presented. The method is based on the idea of the instrumental sensors method (ISM), two well-calibrated sensors are added into the original array. By applying the principle of estimation of signal parameters via rotational invariance techniques (ESPRIT), the direction-of-arrivals (DOAs) and uncertainties can be estimated simultaneously through eigen-decomposition. Compared with the conventional ones, this now method has less computational complexity while has higher estimation precision, what's more, it can overcome the problem of ambiguity. Both theoretical analysis and computer simulations show the effectiveness of the proposed method.

  4. One-Port Direct/Reverse Method for Characterizing VNA Calibration Standards

    CERN Document Server

    Monsalve, Raul A; Mozdzen, Thomas J; Bowman, Judd D

    2016-01-01

    This paper introduces a one-port method for estimating model parameters of VNA calibration standards. The method involves measuring the standards through an asymmetrical passive network connected in direct mode and then in reverse mode, and using these measurements to compute the S-parameters of the network. The free parameters of the calibration standards are estimated by minimizing a figure of merit based on the expected equality of the S-parameters of the network when used in direct and reverse modes. The capabilities of the method are demonstrated through simulations, and real measurements are used to estimate the actual offset delay of a 50-$\\mathbf{\\Omega}$ calibration load that is assigned zero delay by the manufacturer. The estimated delay is $38.8$ ps with a $1\\sigma$ uncertainty of $2.1$ ps for this particular load. This result is verified through measurements of a terminated airline. The measurements agree better with theoretical models of the airline when the reference plane is calibrated using th...

  5. Calibration of UHF Sensors for GIS: Comparison of Different Methods and Testing of a Calibration System Based on a Conical Antenna%Calibration of UHF Sensors for GIS: Comparison of Different Methods and Testing of a Calibration System Based on a Conical Antenna

    Institute of Scientific and Technical Information of China (English)

    David Gautschi; Pierre Bertholet

    2011-01-01

    Different methods of calibrating ultra high frequency(UHF) sensors for gas-insulated substations (GIS) were investigated in the past. The first approach was to use strip lines, triplates and TEM calibration cells. These cells had already been in use for years for example to test the electromagnetic compatibility of electronic devices. The smaller the size of the cell, the higher its bandwidth-but the cell should be large enough to not disturb the electric field with the installed sensor under test. To overcome this problem, a calibration procedure using a gigahertz transverse e- lectromagnetic(GTEM) test cell and a pulsed signal source were introduced in 1997. Although this procedure has many advantages and is easy to understand, measurements show several shortcomings of this calibration method. To overcome the disadvantages of the known systems, a calibration cell using a monopole cone antenna and a metallic ground plane were developed and tested. The UHF sensor was placed in a region with minimum distortion of the elec- tric field due to its installation. Experience shows that the new method for calibrating UHF sensors is necessary in or- der to overcome the limits in the calibration of large sensors and to suppress the propagation of higher order modes and reflections. Due to its surprisingly simple structure, its low price and low overall measurement uncertainty, it is the preferred method for calibrating UHF sensors for GIS applications.

  6. Standard test method for calibration of surface/stress measuring devices

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1997-01-01

    Return to Contents page 1.1 This test method covers calibration or verification of calibration, or both, of surface-stress measuring devices used to measure stress in annealed and heat-strengthened or tempered glass using polariscopic or refractometry based principles. 1.2 This test method is nondestructive. 1.3 This test method uses transmitted light, and therefore, is applicable to light-transmitting glasses. 1.4 This test method is not applicable to chemically tempered glass. 1.5 Using the procedure described, surface stresses can be measured only on the “tin” side of float glass. 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  7. Four-step DOAS calibration method of SO2 in flue gas

    Institute of Scientific and Technical Information of China (English)

    Tao Zhou; Bin Liu; Changku Sun

    2009-01-01

    SO2 monitoring in the flue gas of a coal burning boiler is important for environmental protection.The nonlinearity of practical condition causes deviation from theoretical law.On the basis of the Lambert-Beer Law,a new four-step calibration method is introduced. This method includes cross section interpolation,weighting spectral region combination,acquiring the spectrum with new calibration devices,and least-square fitting.Compared with conventional methods,this new method is low cost,convenient,and accurate.In the proof test,SO2 samples with different concentrations are measured.The average errors are less than 1.5%,while the maximum deviation is less than 4.5%.

  8. Method of array shape calibration based on time delay estimation using two auxiliary sources

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; WU Lixin; CUI Jie; Jim Lynch; Arthur Newhall

    2007-01-01

    As for a flexible horizontal array deployed in the sea, it is difficult to obtain each sensor's precise relative position. Therefore a method of array shape calibration is proposed.The method is described as follows. Firstly two separate auxiliary sources are deployed. Secondly time delay of each sensor's received signal is estimated. Finally, with the aid of GPS location of the sources and the horizontal array, relative sensor positions of the horizontal array can be determined. The estimation of relative sensor positions is unbiased. Simultaneously,simulation analysis has been done to estimate its standard variance, and the optimal flare angle of the two sources has been derived. Data of 2001 Asian Sea International Experiment have been used to validate the method. After array calibration, measured source azimuth angle agrees with the real one, and measured array gain agrees with the theoretical gain. In conclusion, the theoretical and experimental results both show that the method can determine each sensor's relative position precisely.

  9. Follow-up investigations of GPHS motion during heat pulse intervals of reentries from gravity-assist trajectories

    International Nuclear Information System (INIS)

    Motion studies of the General Purpose Heat Source Module, GPHS, which were conducted in the heat pulse intervals associated with entries from earth gravity assist trajectories. The APL six-degree-of-freedom reentry program designated TMAGRA6C was used. The objectives of the studies were to (1) determine whether the GPHS module entering the earth's atmosphere from an earth-gravity-assist trajectory has a preferred orientation during the heat pulse of reentry, (2) determine the effect of magnus force on the roll rate and angle of attack of the GPHS during an EGA entry, (3) determine the effect of the magnitude of pitch and roll damping on the GPHS motion

  10. A fully Bayesian method for jointly fitting instrumental calibration and X-ray spectral models

    International Nuclear Information System (INIS)

    Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is 'pragmatic' in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use a principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or γ-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.

  11. Calibration Method for Confocal X-Ray Microanalysis with Polychromatic Excitation

    OpenAIRE

    Sosa, C.; Stoytschew, V.; Leani, J.; H. J. Sánchez; C. A. Pérez; R. D. Perez

    2015-01-01

    To apply the fundamental parameters method at the confocal setup the knowledge of the sensitivity of the spectrometer is required which depends on the characteristics of two X-ray lenses: one in the excitation channel and another in the detection channel. For the particular case of polychromatic excitation, the theory shows that the focalization properties of the excitation lens for all incident energies affect the X-ray fluorescence intensity. Therefore the traditional calibration method bas...

  12. A Fully Bayesian Method for Jointly Fitting Instrumental Calibration and X-Ray Spectral Models

    Science.gov (United States)

    Xu, Jin; van Dyk, David A.; Kashyap, Vinay L.; Siemiginowska, Aneta; Connors, Alanna; Drake, Jeremy; Meng, Xiao-Li; Ratzlaff, Pete; Yu, Yaming

    2014-10-01

    Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is "pragmatic" in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use a principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or γ-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.

  13. A fully Bayesian method for jointly fitting instrumental calibration and X-ray spectral models

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jin; Yu, Yaming [Department of Statistics, University of California, Irvine, Irvine, CA 92697-1250 (United States); Van Dyk, David A. [Statistics Section, Imperial College London, Huxley Building, South Kensington Campus, London SW7 2AZ (United Kingdom); Kashyap, Vinay L.; Siemiginowska, Aneta; Drake, Jeremy; Ratzlaff, Pete [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Connors, Alanna; Meng, Xiao-Li, E-mail: jinx@uci.edu, E-mail: yamingy@ics.uci.edu, E-mail: dvandyk@imperial.ac.uk, E-mail: vkashyap@cfa.harvard.edu, E-mail: asiemiginowska@cfa.harvard.edu, E-mail: jdrake@cfa.harvard.edu, E-mail: pratzlaff@cfa.harvard.edu, E-mail: meng@stat.harvard.edu [Department of Statistics, Harvard University, 1 Oxford Street, Cambridge, MA 02138 (United States)

    2014-10-20

    Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is 'pragmatic' in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use a principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or γ-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.

  14. A Curve-fitting Calibration Method applied for Ultrasonic Flow-meter

    OpenAIRE

    Yong Luo; Rangding Wang; Ling Yao

    2013-01-01

    As the influence of fluid distribution in the internal pipe, the measurement characteristics of theory and practice exist significant differences in Ultrasonic Flow-meter(USF). Through analysis of fluid state, the method of curve-fitting is applied for the calibration of USF. Experimental results show that the USF can achieve level-1 accuracy with just a correction of 5 flow points, and this method performs a low computational complexity and strong practicality.  

  15. A Curve-fitting Calibration Method applied for Ultrasonic Flow-meter

    Directory of Open Access Journals (Sweden)

    Yong Luo

    2013-10-01

    Full Text Available As the influence of fluid distribution in the internal pipe, the measurement characteristics of theory and practice exist significant differences in Ultrasonic Flow-meter(USF. Through analysis of fluid state, the method of curve-fitting is applied for the calibration of USF. Experimental results show that the USF can achieve level-1 accuracy with just a correction of 5 flow points, and this method performs a low computational complexity and strong practicality.  

  16. Development and evaluation of a method of calibrating medical displays based on fixed adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Sund, Patrik, E-mail: patrik.sund@vgregion.se; Månsson, Lars Gunnar; Båth, Magnus [Department of Medical Physics and Biomedical Engineering, Sahlgrenska University Hospital, Gothenburg SE-41345, Sweden and Department of Radiation Physics, University of Gothenburg, Gothenburg SE-41345 (Sweden)

    2015-04-15

    Purpose: The purpose of this work was to develop and evaluate a new method for calibration of medical displays that includes the effect of fixed adaptation and by using equipment and luminance levels typical for a modern radiology department. Methods: Low contrast sinusoidal test patterns were derived at nine luminance levels from 2 to 600 cd/m{sup 2} and used in a two alternative forced choice observer study, where the adaptation level was fixed at the logarithmic average of 35 cd/m{sup 2}. The contrast sensitivity at each luminance level was derived by establishing a linear relationship between the ten pattern contrast levels used at every luminance level and a detectability index (d′) calculated from the fraction of correct responses. A Gaussian function was fitted to the data and normalized to the adaptation level. The corresponding equation was used in a display calibration method that included the grayscale standard display function (GSDF) but compensated for fixed adaptation. In the evaluation study, the contrast of circular objects with a fixed pixel contrast was displayed using both calibration methods and was rated on a five-grade scale. Results were calculated using a visual grading characteristics method. Error estimations in both observer studies were derived using a bootstrap method. Results: The contrast sensitivities for the darkest and brightest patterns compared to the contrast sensitivity at the adaptation luminance were 37% and 56%, respectively. The obtained Gaussian fit corresponded well with similar studies. The evaluation study showed a higher degree of equally distributed contrast throughout the luminance range with the calibration method compensated for fixed adaptation than for the GSDF. The two lowest scores for the GSDF were obtained for the darkest and brightest patterns. These scores were significantly lower than the lowest score obtained for the compensated GSDF. For the GSDF, the scores for all luminance levels were statistically

  17. [Research on absolute calibration of sun channel of sun photometer using laser raster scanning method].

    Science.gov (United States)

    Xu, Wen-Bin; Li, Jian-Jun; Zheng, Xiao-Bing

    2013-01-01

    In the present paper, a new calibration method of absolute spectral irradiance responsivity of sun channel of sun photometer was developed. A tunable laser was used as source and a standard tranfer detector, calibrated against cryogenic absolute radiometer, was used to measure laser beam power. By raster scanning of a single collimated laser beam to generate the uniform irradiance field at the plane of effective aperture stop of sun photometer, the absolute irradiance responsivity of center wavelength of the 870 nm unpolarized sun channels of sun photometer was obtained accurately. The relative spectral irradiance responsivity of corresponding channel was obtained by using lamp-monochromator system and then used to acquire the absolute spectral irradiance responsivity in the laboratory. On the basis of the above results, the top-of-the-atmosphere responsive constant V0 was obtained by integration with extraterrestrial solar spectral irradiance data. Comparing the calibration result with that from GSFC, NASA in 2009, the difference is only 3.75%. In the last, the uncertainties of calibration were evaluated and reached to 2.06%. The principle feasibility of the new method was validated.

  18. A calibration method for proposed XRF measurements of arsenic and selenium in nail clippings.

    Science.gov (United States)

    Gherase, Mihai R; Fleming, David E B

    2011-10-21

    A calibration method for proposed x-ray fluorescence (XRF) measurements of arsenic and selenium in nail clippings is demonstrated. Phantom nail clippings were produced from a whole nail phantom (0.7 mm thickness, 25 × 25 mm(2) area) and contained equal concentrations of arsenic and selenium ranging from 0 to 20 µg g(-1) in increments of 5 µg g(-1). The phantom nail clippings were then grouped in samples of five different masses: 20, 40, 60, 80 and 100 mg for each concentration. Experimental x-ray spectra were acquired for each of the sample masses using a portable x-ray tube and a detector unit. Calibration lines (XRF signal in a number of counts versus stoichiometric elemental concentration) were produced for each of the two elements. A semi-empirical relationship between the mass of the nail phantoms (m) and the slope of the calibration line (s) was determined separately for arsenic and selenium. Using this calibration method, one can estimate elemental concentrations and their uncertainties from the XRF spectra of human nail clippings. PMID:21937772

  19. A calibration method for proposed XRF measurements of arsenic and selenium in nail clippings

    Energy Technology Data Exchange (ETDEWEB)

    Gherase, Mihai R; Fleming, David E B, E-mail: mgherase@mta.ca [Physics Department, Mount Allison University, Sackville, New Brunswick, E4L 1E6 (Canada)

    2011-10-21

    A calibration method for proposed x-ray fluorescence (XRF) measurements of arsenic and selenium in nail clippings is demonstrated. Phantom nail clippings were produced from a whole nail phantom (0.7 mm thickness, 25 x 25 mm{sup 2} area) and contained equal concentrations of arsenic and selenium ranging from 0 to 20 {mu}g g{sup -1} in increments of 5 {mu}g g{sup -1}. The phantom nail clippings were then grouped in samples of five different masses: 20, 40, 60, 80 and 100 mg for each concentration. Experimental x-ray spectra were acquired for each of the sample masses using a portable x-ray tube and a detector unit. Calibration lines (XRF signal in a number of counts versus stoichiometric elemental concentration) were produced for each of the two elements. A semi-empirical relationship between the mass of the nail phantoms (m) and the slope of the calibration line (s) was determined separately for arsenic and selenium. Using this calibration method, one can estimate elemental concentrations and their uncertainties from the XRF spectra of human nail clippings. (note)

  20. A calibration method for proposed XRF measurements of arsenic and selenium in nail clippings

    Science.gov (United States)

    Gherase, Mihai R.; Fleming, David E. B.

    2011-10-01

    A calibration method for proposed x-ray fluorescence (XRF) measurements of arsenic and selenium in nail clippings is demonstrated. Phantom nail clippings were produced from a whole nail phantom (0.7 mm thickness, 25 × 25 mm2 area) and contained equal concentrations of arsenic and selenium ranging from 0 to 20 µg g-1 in increments of 5 µg g-1. The phantom nail clippings were then grouped in samples of five different masses: 20, 40, 60, 80 and 100 mg for each concentration. Experimental x-ray spectra were acquired for each of the sample masses using a portable x-ray tube and a detector unit. Calibration lines (XRF signal in a number of counts versus stoichiometric elemental concentration) were produced for each of the two elements. A semi-empirical relationship between the mass of the nail phantoms (m) and the slope of the calibration line (s) was determined separately for arsenic and selenium. Using this calibration method, one can estimate elemental concentrations and their uncertainties from the XRF spectra of human nail clippings.

  1. Switching field dependence on heating pulse duration in thermally assisted magnetic random access memories

    Energy Technology Data Exchange (ETDEWEB)

    Papusoi, C. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)], E-mail: cristian_papusoi@yahoo.com; Conraux, Y.; Prejbeanu, I.L. [Crocus Technology, 5 Robert Schumann, BP 1510, 38025 Grenoble (France); Sousa, R.; Dieny, B. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)

    2009-08-15

    The minimum applied field H{sub SW} required to reverse the magnetic moment of the ferromagnetic/antiferromagnetic storage layer of a thermally assisted magnetic random access memory (TA-MRAM) device during the application of a heating electric pulse is investigated as a function of pulse power P{sub HP} and duration {delta}. For the same power of the heating pulse P{sub HP} (or, equivalently, for the same temperature of the storage layer), H{sub SW} increases with decreasing heating time {delta}. This behavior is consistently interpreted by a thermally activated propagating domain-wall switching model, corroborated by a real-time study of switching. The increase of H{sub SW} with decreasing pulse width introduces a constraint for the minimum power consumption of a TA-MRAM where writing combines heating and magnetic field application.

  2. Hybrid PSO-ASVR-based method for data fitting in the calibration of infrared radiometer

    Science.gov (United States)

    Yang, Sen; Li, Chengwei

    2016-06-01

    The present paper describes a hybrid particle swarm optimization-adaptive support vector regression (PSO-ASVR)-based method for data fitting in the calibration of infrared radiometer. The proposed hybrid PSO-ASVR-based method is based on PSO in combination with Adaptive Processing and Support Vector Regression (SVR). The optimization technique involves setting parameters in the ASVR fitting procedure, which significantly improves the fitting accuracy. However, its use in the calibration of infrared radiometer has not yet been widely explored. Bearing this in mind, the PSO-ASVR-based method, which is based on the statistical learning theory, is successfully used here to get the relationship between the radiation of a standard source and the response of an infrared radiometer. Main advantages of this method are the flexible adjustment mechanism in data processing and the optimization mechanism in a kernel parameter setting of SVR. Numerical examples and applications to the calibration of infrared radiometer are performed to verify the performance of PSO-ASVR-based method compared to conventional data fitting methods.

  3. Computer aided method for colour calibration and analysis of digital rock photographs

    Directory of Open Access Journals (Sweden)

    Matic Potočnik

    2015-12-01

    Full Text Available The methods used in geology to determine colour and colour coverage are expensive, time consuming, and/ or subjective. Estimates of colour coverage can only be approximate since they are based on rough comparisonbased measuring etalons and subjective estimation, which is dependent upon the skill and experience of the person performing the estimation. We present a method which accelerates, simplifis, and objectifis these tasks using a computer application. It automatically calibrates the colours of a digital photo, and enables the user to read colour values and coverage, even after returning from fild work. Colour identifiation is based on the Munsell colour system. For the purposes of colour calibration we use the X-Rite ColorChecker Passport colour chart placed onto the photographed scene. Our computer application detects the ColorChecker colour chart, and fids a colour space transformation to calibrate the colour in the photo. The user can then use the application to read colours within selected points or regions of the photo. The results of the computerised colour calibration were compared to the reference values of the ColorChecker chart. The values slightly deviate from the exact values, but the deviation is around the limit of human capability for visual comparison. We have devised an experiment, which compares the precision of the computerised colour analysis and manual colour analysis performed on a variety of rock samples with the help of geology students using Munsell Rock-color Chart. The analysis showed that the precision of manual comparative identifiation on multicoloured samples is somewhat problematic, since the choice of representative colours and observation points for a certain part of a sample are subjective. The computer based method has the edge in verifibility and repeatability of the analysis since the application the original photo to be saved with colour calibration, and tagging of colouranalysed points and regions.

  4. Application of heat pulse injections for investigating shallow hyporheic flow in a lowland river

    Science.gov (United States)

    Angermann, Lisa; Krause, Stefan; Lewandowski, Joerg

    2012-10-01

    Hyporheic zone processes can have significant impact on groundwater and surface water resources. Detailed knowledge of exchange flow patterns is crucial for understanding the ecohydrological and biogeochemical functioning of river corridors. In particular, small-scale hyporheic exchange flow is still poorly understood, partially because of the lack of adequate in situ monitoring technology. This paper investigates the spatial heterogeneity of hyporheic exchange flow in a lowland river at multiple scales. It demonstrates the conjunctive use of active heat pulse tracing at shallow depths (15 cm) and vertical hydraulic gradients (VHG) at 120-150 cm streambed depth for improving the understanding of hyporheic exchange flow processes. Generally positive VHG indicated a regional dominance of groundwater up-welling. High and temporally variable VHG were used to identify confined conditions caused by low conductivity layers in the subsurface (low connectivity), while locations with lower and temporally less variable VHG indicated free groundwater up-welling (high connectivity) in highly conductive sediments. A heat pulse sensor (HPS) was applied for identifying shallow hyporheic flow at three locations representative for high versus low streambed connectivity. Shallow hyporheic flow patterns were found to be spatially heterogeneous. Subsurface flow could only partially be explained by streambed topography. Surface water infiltration and horizontal flow coincided with inhibited groundwater up-welling, whereas locations with high streambed connectivity were characterized by increased up-welling. The combined information of spatiotemporal VHG variability and flow vector frequency distribution by HPS has the potential to improve the understanding of impacts of streambed topography and subsurface stratification on hyporheic flow patterns.

  5. A Focusing Method in the Calibration Process of Image Sensors Based on IOFBs

    Directory of Open Access Journals (Sweden)

    Pedro R. Fernández

    2009-12-01

    Full Text Available A focusing procedure in the calibration process of image sensors based on Incoherent Optical Fiber Bundles (IOFBs is described using the information extracted from fibers. These procedures differ from any other currently known focusing method due to the non spatial in-out correspondence between fibers, which produces a natural codification of the image to transmit. Focus measuring is essential prior to carrying out calibration in order to guarantee accurate processing and decoding. Four algorithms have been developed to estimate the focus measure; two methods based on mean grey level, and the other two based on variance. In this paper, a few simple focus measures are defined and compared. Some experimental results referred to the focus measure and the accuracy of the developed methods are discussed in order to demonstrate its effectiveness.

  6. Study and Realization of the Basic Methods of the Calibration in Stereopsis For Augmented Reality

    Directory of Open Access Journals (Sweden)

    Fezani Mustapha

    2007-01-01

    Full Text Available Augmented reality (RA is aimed at ameliorating our perception of the real world by addition of elements which are not a priori observable by the human eye. RA is define as a system able of combining real and virtual pictures, in 3D and real-time. The virtual objects must be cast in a consistent manner in real pictures. In practice, objects are positioned in a landmark linked to the scene, and objective is to determine the point of view of the camera (position and orientation in this landmark, which we are going to see in the next scene of calibration of camera. Camera calibration is a fundamental problem in computer vision. In this paper, we developed a semi automatic calibration method for our augmented reality system, which uses corner detection to extract pixel coordinates of projection points and uses homography to build the correspondence. So my method allows reconstruction 3D of the scene. To find resolution they use projections instead of the Euclidean methods which allow acquiring a good result with average error between the re-projected points and pixel points is round 2 pixels. Potential applications of this method are: applications real-time in the domains of medicine, service of fabricated objects, industry.

  7. Effects of sensor calibration, balancing and parametrization on the signal space separation method

    Energy Technology Data Exchange (ETDEWEB)

    Nurminen, J [BioMag laboratory, Hospital District of Helsinki and Uusimaa HUSLAB, Helsinki University Central Hospital, PL 340, FI-00029 HUS (Finland); Taulu, S [Elekta Neuromag Oy, Helsinki, FI-00510 (Finland); Okada, Y [Biomedical Research and Integrative NeuroImaging (BRaIN Imaging) Center, University of New Mexico, Albuquerque, NM 87131 (United States)], E-mail: jussi@biomag.hus.fi

    2008-04-07

    Signal space separation (SSS) is a novel method for processing multichannel biomagnetic data. It is useful for a variety of applications including interference suppression, movement compensation and conversion of measurements between sensor arrays. The performance of SSS has been examined mainly on a 306-channel whole-head magnetoencephalography system. To facilitate the adaptation of the method to other biomagnetometer systems, the effect of various properties of the sensor array on its performance needs to be studied. To this end, we examined the effects of gradiometer imbalance, sensor calibration errors and erroneous sensor geometry information on SSS using simulations. The results indicate that depending on the application, gradiometer balance on the level of 0.1% to 0.5% may be needed for satisfactory SSS performance. For wire-wound gradiometers, this requires very careful attention in manufacturing. Errors in calibration coefficients and geometry information were found to have less significance.

  8. A New Method to Calibrate the Stellar Color/Surface-Brightness Relation

    CERN Document Server

    Gould, Andrew

    2014-01-01

    I show that the standard microlensing technique to measure the angular radius of a star using color/surface-brightness relations can be inverted, via late-time proper motion measurements, to calibrate these relations. The method is especially useful for very metal-rich stars because such stars are in short supply in the solar neighborhood where other methods are most effective, but very abundant in Galactic bulge microlensing fields. I provide a list of eight spectroscopically identified high-metallicity bulge stars with the requisite finite-source effects, seven of which will be suitable calibrators when the Giant Magellan Telescope comes on line. Many more such sources can be extracted from current and future microlensing surveys.

  9. An Improved Method for the Geometrical Calibration of Parallelogram-based Parallel Robots

    OpenAIRE

    Savoure, Ludovic; Maurine, Patrick; Corbel, David; Krut, Sébastien

    2006-01-01

    International audience This paper presents an improved method for the geometrical calibration of parallel robots for which the structure is based upon some parallelogram mechanisms. Its originality is to identify the complete geometry of the mechanism's parallelograms, and to compensate the positioning error of the TCP (Tool Centre Point), due to the infinitesimal rotation of the traveling plate, induced by the parallelogram geometrical errors. The main difficulties are: (i) to derive the ...

  10. A New Method to Calibrate Attachment Angles of Data Loggers in Swimming Sharks

    OpenAIRE

    Shizuka Kawatsu; Katsufumi Sato; Yuuki Watanabe; Susumu Hyodo; Breves, Jason P.; Bradley K. Fox; E Gordon Grau; Nobuyuki Miyazaki

    2010-01-01

    Recently, animal-borne accelerometers have been used to record the pitch angle of aquatic animals during swimming. When evaluating pitch angle, it is necessary to consider a discrepancy between the angle of an accelerometer and the long axis of an animal. In this study, we attached accelerometers to 17 free-ranging scalloped hammerhead shark (Sphyrna lewini) pups from Kaneohe Bay, Hawaii. Although there are methods to calibrate attachment angles of accelerometers, we confirmed that previous ...

  11. Differential Binary Encoding Method for Calibrating Image Sensors Based on IOFBs

    OpenAIRE

    Ángel Cano; Ignacio Bravo; Felipe Espinosa; José Luis Lázaro-Galilea; Alfredo Gardel; Pedro R. Fernández

    2012-01-01

    Image transmission using incoherent optical fiber bundles (IOFBs) requires prior calibration to obtain the spatial in-out fiber correspondence necessary to reconstruct the image captured by the pseudo-sensor. This information is recorded in a Look-Up Table called the Reconstruction Table (RT), used later for reordering the fiber positions and reconstructing the original image. This paper presents a very fast method based on image-scanning using spaces encoded by a weighted binary code to obta...

  12. Calibration uncertainty

    DEFF Research Database (Denmark)

    Heydorn, Kaj; Anglov, Thomas

    2002-01-01

    uncertainty was verified from independent measurements of the same sample by demonstrating statistical control of analytical results and the absence of bias. The proposed method takes into account uncertainties of the measurement, as well as of the amount of calibrant. It is applicable to all types......Methods recommended by the International Standardization Organisation and Eurachem are not satisfactory for the correct estimation of calibration uncertainty. A novel approach is introduced and tested on actual calibration data for the determination of Pb by ICP-AES. The improved calibration...

  13. A vision-based self-calibration method for robotic visual inspection systems.

    Science.gov (United States)

    Yin, Shibin; Ren, Yongjie; Zhu, Jigui; Yang, Shourui; Ye, Shenghua

    2013-01-01

    A vision-based robot self-calibration method is proposed in this paper to evaluate the kinematic parameter errors of a robot using a visual sensor mounted on its end-effector. This approach could be performed in the industrial field without external, expensive apparatus or an elaborate setup. A robot Tool Center Point (TCP) is defined in the structural model of a line-structured laser sensor, and aligned to a reference point fixed in the robot workspace. A mathematical model is established to formulate the misalignment errors with kinematic parameter errors and TCP position errors. Based on the fixed point constraints, the kinematic parameter errors and TCP position errors are identified with an iterative algorithm. Compared to the conventional methods, this proposed method eliminates the need for a robot-based-frame and hand-to-eye calibrations, shortens the error propagation chain, and makes the calibration process more accurate and convenient. A validation experiment is performed on an ABB IRB2400 robot. An optimal configuration on the number and distribution of fixed points in the robot workspace is obtained based on the experimental results. Comparative experiments reveal that there is a significant improvement of the measuring accuracy of the robotic visual inspection system. PMID:24300597

  14. Calibration of Soil Electromagnetic Conductivity in Inverted Salinity Profiles with an Integration Method

    Institute of Scientific and Technical Information of China (English)

    YAO Rong-Jiang; YANG Jin-Song; LIU Guang-Ming

    2007-01-01

    Various calibration methods have been propounded to determine profiles of apparent bulk soil electrical conductivity (ECa)and soil electrical conductivity of a saturated soil paste extract(ECe)or a 1:5 soil water extract(EC1:5)using an electromagnetic induction instrument(EM38).The modeled coefficients,one of the successful and classical methods hitherto,were chosen to calibrate the EM38 measurements of the inverted salinity profiles of characteristic coastal saline soils at selected sites of Xincao Farm,Jiangsu Province,China.However,this method required three parameters for each depth layer.An integration approach,based on an exponential decay profile model,was proposed and the model was fitted to all the calibration sites.The obtained model can then be used to predict EC1:5 at a certain depth from electromagnetic measurements made using the EM38 device positioned in horizontal and vertical positions at the soil surface.This exponential decay model predicted the EC1:5 well according to the results of a one-way analysis of variance,and the further comparison indicated that the modeled coefficients appeared to be slightly superior to.but not statistically different from,this exponential decay model.Nevertheless,this exponential decay model was more significant and practical because it depended on less empirical parameters and could be used to perform point predictions of EC1:5 continuously with depth.

  15. A vision-based self-calibration method for robotic visual inspection systems.

    Science.gov (United States)

    Yin, Shibin; Ren, Yongjie; Zhu, Jigui; Yang, Shourui; Ye, Shenghua

    2013-12-03

    A vision-based robot self-calibration method is proposed in this paper to evaluate the kinematic parameter errors of a robot using a visual sensor mounted on its end-effector. This approach could be performed in the industrial field without external, expensive apparatus or an elaborate setup. A robot Tool Center Point (TCP) is defined in the structural model of a line-structured laser sensor, and aligned to a reference point fixed in the robot workspace. A mathematical model is established to formulate the misalignment errors with kinematic parameter errors and TCP position errors. Based on the fixed point constraints, the kinematic parameter errors and TCP position errors are identified with an iterative algorithm. Compared to the conventional methods, this proposed method eliminates the need for a robot-based-frame and hand-to-eye calibrations, shortens the error propagation chain, and makes the calibration process more accurate and convenient. A validation experiment is performed on an ABB IRB2400 robot. An optimal configuration on the number and distribution of fixed points in the robot workspace is obtained based on the experimental results. Comparative experiments reveal that there is a significant improvement of the measuring accuracy of the robotic visual inspection system.

  16. A landmark-based method for the geometrical 3D calibration of scanning microscopes

    Energy Technology Data Exchange (ETDEWEB)

    Ritter, M.

    2007-04-27

    This thesis presents a new strategy and a spatial method for the geometric calibration of 3D measurement devices at the micro-range, based on spatial reference structures with nanometersized landmarks (nanomarkers). The new method was successfully applied for the 3D calibration of scanning probe microscopes (SPM) and confocal laser scanning microscopes (CLSM). Moreover, the spatial method was also used for the photogrammetric self-calibration of scanning electron microscopes (SEM). In order to implement the calibration strategy to all scanning microscopes used, the landmark-based principle of reference points often applied at land survey or at close-range applications has been transferred to the nano- and micro-range in the form of nanomarker. In order to function as a support to the nanomarkers, slope-shaped step pyramids have been developed and fabricated by focused ion beam (FIB) induced metal deposition. These FIB produced 3D microstructures have been sized to embrace most of the measurement volume of the scanning microscopes. Additionally, their special design allows the homogenous distribution of the nanomarkers. The nanomarkers were applied onto the support and the plateaus of the slope-step pyramids by FIB etching (milling) as landmarks with as little as several hundreds of nanometers in diameter. The nanomarkers are either of point-, or ring-shaped design. They are optimized so that they can be spatially measured by SPM and CLSM, and, imaged and photogrammetrically analyzed on the basis of SEM data. The centre of the each nanomarker serves as reference point in the measurement data or images. By applying image processing routines, the image (2D) or object (3D) coordinates of each nanomarker has been determined with subpixel accuracy. The correlative analysis of the SPM, CLSM and photogrammetric SEM measurement data after 3D calibration resulted in mean residues in the measured coordinates of as little as 13 nm. Without the coupling factors the mean

  17. Development of an adjoint sensitivity method for site characterization, uncertainty analysis, and code calibration/validation

    Energy Technology Data Exchange (ETDEWEB)

    Lu, A.H.

    1991-09-01

    The adjoint method is applied to groundwater flow-mass transport coupled equations in variably saturated media. The sensitivity coefficients derived by this method can be calculated by a single execution for each performance measure regardless of the number of parameters in question. The method provides an efficient and effective way to rank the importance of the parameters, so that data collection can be guided in support of site characterization programs. The developed code will facilitate the sensitivity/uncertainty analysis in both model prediction and model calibration/validation. 13 refs., 1 tab.

  18. A Calibration Method Based on Linear InGaAs in Fiber Grating Sensors Interrogation System

    Institute of Scientific and Technical Information of China (English)

    TAO Jun; ZHANG Xia

    2009-01-01

    In accordance with the characteristics of wavelength shift detection in fiber grating sensor interrogation system, the wavelength interrogation system which uses linear InGaAs as the spectrum receiver is proposed. Orientation of optic spectrum line affects the silt of volume phase grating and size of InGaAs photosensitive unit, thus the calibration method is needed. Based on an analysis of InGaAs imaging model, least square curve fitting method is proposed to detect spectrum wavelength and InGaAs photosensitive unit position. The experimental results show that the methods are effective and the demodulation system precision is improved.

  19. Calibration method of the time synchronization error of many data acquisition nodes in the chained system

    Science.gov (United States)

    Jiang, Jia-jia; Duan, Fa-jie; Chen, Jin; Zhang, Chao; Wang, Kai; Chang, Zong-jie

    2012-08-01

    Time synchronization is very important in a distributed chained seismic acquisition system with a large number of data acquisition nodes (DANs). The time synchronization error has two causes. On the one hand, there is a large accumulated propagation delay when commands propagate from the analysis and control system to multiple distant DANs, which makes it impossible for different DANs to receive the same command synchronously. Unfortunately, the propagation delay of commands (PDCs) varies in different application environments. On the other hand, the phase jitter of both the master clock and the clock recovery phase-locked loop, which is designed to extract the timing signal, may also cause the time synchronization error. In this paper, in order to achieve accurate time synchronization, a novel calibration method is proposed which can align the PDCs of all of the DANs in real time and overcome the time synchronization error caused by the phase jitter. Firstly, we give a quantitative analysis of the time synchronization error caused by both the PDCs and the phase jitter. Secondly, we propose a back and forth model (BFM) and a transmission delay measurement method (TDMM) to overcome these difficulties. Furthermore, the BFM is designed as the hardware configuration to measure the PDCs and calibrate the time synchronization error. The TDMM is used to measure the PDCs accurately. Thirdly, in order to overcome the time synchronization error caused by the phase jitter, a compression and mapping algorithm (CMA) is presented. Finally, based on the proposed BFM, TDMM and CMA, a united calibration algorithm is developed to overcome the time synchronization error caused by both the PDCs and the phase jitter. The simulation experiment results show the effectiveness of the calibration method proposed in this paper.

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

    Science.gov (United States)

    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.

  1. Semi-automated calibration method for modelling of mountain permafrost evolution in Switzerland

    Science.gov (United States)

    Marmy, A.; Rajczak, J.; Delaloye, R.; Hilbich, C.; Hoelzle, M.; Kotlarski, S.; Lambiel, C.; Noetzli, J.; Phillips, M.; Salzmann, N.; Staub, B.; Hauck, C.

    2015-09-01

    Permafrost is a widespread phenomenon in the European Alps. Many important topics such as the future evolution of permafrost related to climate change and the detection of permafrost related to potential natural hazards sites are of major concern to our society. Numerical permafrost models are the only tools which facilitate the projection of the future evolution of permafrost. Due to the complexity of the processes involved and the heterogeneity of Alpine terrain, models must be carefully calibrated and results should be compared with observations at the site (borehole) scale. However, a large number of local point data are necessary to obtain a broad overview of the thermal evolution of mountain permafrost over a larger area, such as the Swiss Alps, and the site-specific model calibration of each point would be time-consuming. To face this issue, this paper presents a semi-automated calibration method using the Generalized Likelihood Uncertainty Estimation (GLUE) as implemented in a 1-D soil model (CoupModel) and applies it to six permafrost sites in the Swiss Alps prior to long-term permafrost evolution simulations. We show that this automated calibration method is able to accurately reproduce the main thermal condition characteristics with some limitations at sites with unique conditions such as 3-D air or water circulation, which have to be calibrated manually. The calibration obtained was used for RCM-based long-term simulations under the A1B climate scenario specifically downscaled at each borehole site. The projection shows general permafrost degradation with thawing at 10 m, even partially reaching 20 m depths until the end of the century, but with different timing among the sites. The degradation is more rapid at bedrock sites whereas ice-rich sites with a blocky surface cover showed a reduced sensitivity to climate change. The snow cover duration is expected to be reduced drastically (between -20 to -37 %) impacting the ground thermal regime. However

  2. In situ gamma-ray spectrometry for environmental monitoring: A semi empirical calibration method

    International Nuclear Information System (INIS)

    In situ gamma spectrometry using high-purity germanium (HPGe) detectors is a frequently used method for the determination of radionuclide ground deposition levels. Such measurements do, however, require an efficiency calibration based on detector sensitivity and parameters such as soil density and vertical activity distribution. In this work, a novel expression is used for the detector efficiency, incorporating both the influence of photon energy and incidence angle. Detector-specific efficiency data are determined empirically. For the theoretical calculation of the photon fluence at the detector, a three-layer model of finite thickness is developed for the description of soil density and vertical activity distribution. In order to facilitate the calibration of in situ measurements, a PC program has been developed to enable rapid, on-site calculations of radionuclide ground deposition levels. The semi empirical calibration method was tested on in situ measurements with two different detectors, and the results show good agreement with results obtained from traditional soil sampling. (authors)

  3. Methods for Determining the Activity Concentration Calibration Factor for Ventilation Duct in Cyclotron Sites

    International Nuclear Information System (INIS)

    Cyclotrons are commonly used for production of radioactive isotopes for nuclear medicine purposes. The nuclear process requires installation of a ventilation stack. According to the regulations in many countries, the released activity should be monitored and controlled in order to limit air pollution. This requires a stuck radiation detector and determining a converting factor that will translate the radiation detector reading into activity concentration units. Calibrating the conversion factor is done mainly by releasing a known amount of activity. Having a preliminary estimation of the conversion factor, during the site construction stage, is an important option for the duct configuration design, in order to achieve the required detection sensitivity. An algorithm for estimating the stack concentration calibration factor in positron emitting isotopes producing sites was developed. The algorithm which is described in this article is based on three independent methods that consist of MCNP simulations analytical calculations and experimental setup with controlled static calibration releases of gaseous 18F which was produced especially for this purpose by the cyclotron site in Soreq Nuclear Research Center Israel. The specified methods applied on few stack sections with different shapes and sizes

  4. On the Potential of Least Squares Response Method for the Calibration of Superconducting Gravimeters

    Directory of Open Access Journals (Sweden)

    Mahmoud Abd El-Gelil

    2012-01-01

    Full Text Available One of the most important operating procedures after the installation of a superconducting gravimeter (SG is its calibration. The calibration process can identify and evaluate possible time variability in the scale factor and in the hardware anti-aliasing filter response. The SG installed in Cantley, Canada is calibrated using two absolute gravimeters and the data are analysed in the time and frequency domains to estimate the SG scale factor. In the time domain, we use the weighted linear regression method whereas in the frequency domain we use the least squares response method. Rigorous statistical procedures are applied to define data disturbances, outliers, and realistic data noise levels. Using data from JILA-2 and FG5-236 separately, the scale factor is estimated in the time and frequency domains as −78.374±0.012 μGal/V and −78.403±0.075 μGal/V, respectively. The relative accuracy in the time domain is 0.015%. We cannot identify any significant periodicity in the scale factor. The hardware anti-aliasing filter response is tested by injecting known waves into the control electronics of the system. Results show that the anti-aliasing filter response is stable and conforms to the global geodynamics project standards.

  5. Fitness analysis method for magnesium in drinking water with atomic absorption using quadratic curve calibration

    Directory of Open Access Journals (Sweden)

    Esteban Pérez-López

    2014-11-01

    Full Text Available Because of the importance of quantitative chemical analysis in research, quality control, sales of services and other areas of interest , and the limiting of some instrumental analysis methods for quantification with linear calibration curve, sometimes because the short linear dynamic ranges of the analyte, and sometimes by limiting the technique itself, is that there is a need to investigate a little more about the convenience of using quadratic curves for analytical quantification, which seeks demonstrate that it is a valid calculation model for chemical analysis instruments. To this was taken as an analysis method based on the technique and atomic absorption spectroscopy in particular a determination of magnesium in a sample of drinking water Tacares sector Northern Grecia, employing a nonlinear calibration curve and a curve specific quadratic behavior, which was compared with the test results obtained for the same analysis with a linear calibration curve. The results show that the methodology is valid for the determination referred to, with all confidence, since the concentrations are very similar, and as used hypothesis testing can be considered equal.

  6. In situ gamma-ray spectrometry for environmental monitoring: a semi empirical calibration method.

    Science.gov (United States)

    Boson, Jonas; Lidström, Kenneth; Nylén, Torbjörn; Agren, Göran; Johansson, Lennart

    2006-01-01

    In situ gamma spectrometry using high-purity germanium (HPGe) detectors is a frequently used method for the determination of radionuclide ground deposition levels. Such measurements do, however, require an efficiency calibration based on detector sensitivity and parameters such as soil density and vertical activity distribution. In this work, a novel expression is used for the detector efficiency, incorporating both the influence of photon energy and incidence angle. Detector-specific efficiency data are determined empirically. For the theoretical calculation of the photon fluence at the detector, a three-layer model of finite thickness is developed for the description of soil density and vertical activity distribution. In order to facilitate the calibration of in situ measurements, a PC program has been developed to enable rapid, on-site calculations of radionuclide ground deposition levels. The semi empirical calibration method was tested on in situ measurements with two different detectors, and the results show good agreement with results obtained from traditional soil sampling. PMID:16632586

  7. A method for automating calibration and records management for instrumentation and dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    O`Brien, J.M. Jr.; Rushton, R.O.; Burns, R.E. Jr. [Atlan-Tech, Inc., Roswell, GA (United States)

    1993-12-31

    Current industry requirements are becoming more stringent on quality assurance records and documentation for calibration of instruments and dosimetry. A novel method is presented here that will allow a progressive automation scheme to be used in pursuit of that goal. This concept is based on computer-controlled irradiators that can act as stand-alone devices or be interfaced to other components via a computer local area network. In this way, complete systems can be built with modules to create a records management system to meet the needs of small laboratories or large multi-building calibration groups. Different database engines or formats can be used simply by replacing a module. Modules for temperature and pressure monitoring or shipping and receiving can be added, as well as equipment modules for direct IEEE-488 interface to electrometers and other instrumentation.

  8. Heterodyne interferometry method for calibration of a Soleil-Babinet compensator.

    Science.gov (United States)

    Zhang, Wenjing; Zhang, Zhiwei

    2016-05-20

    A method based on the common-path heterodyne interferometer system is proposed for the calibration of a Soleil-Babinet compensator. In this heterodyne interferometer system, which consists of two acousto-optic modulators, the compensator being calibrated is inserted into the signal path. By using the reference beam as the benchmark and a lock-in amplifier (SR844) as the phase retardation collector, retardations of 0 and λ (one wavelength) can be located accurately, and an arbitrary retardation between 0 and λ can also be measured accurately and continuously. By fitting a straight line to the experimental data, we obtained a linear correlation coefficient (R) of 0.995, which indicates that this system is capable of linear phase detection. The experimental results demonstrate determination accuracies of 0.212° and 0.26° and measurement precisions of 0.054° and 0.608° for retardations of 0 and λ, respectively. PMID:27411154

  9. Note: A calibration method to determine the lumped-circuit parameters of a magnetic probe

    Science.gov (United States)

    Li, Fuming; Chen, Zhipeng; Zhu, Lizhi; Liu, Hai; Wang, Zhijiang; Zhuang, Ge

    2016-06-01

    This paper describes a novel method to determine the lumped-circuit parameters of a magnetic inductive probe for calibration by using Helmholtz coils with high frequency power supply (frequency range: 10 kHz-400 kHz). The whole calibration circuit system can be separated into two parts: "generator" circuit and "receiver" circuit. By implementing the Fourier transform, two analytical lumped-circuit models, with respect to these separated circuits, are constructed to obtain the transfer function between each other. Herein, the precise lumped-circuit parameters (including the resistance, inductance, and capacitance) of the magnetic probe can be determined by fitting the experimental data to the transfer function. Regarding the fitting results, the finite impedance of magnetic probe can be used to analyze the transmission of a high-frequency signal between magnetic probes, cables, and acquisition system.

  10. Mathematical methods and algorithms for calibration data processing in the case of spiral scanning

    International Nuclear Information System (INIS)

    Mathematical methods of calibration data processing implemented as CALIBR program are described. This program is intended for weakly testing of the ''Spiral Reader'' automatic device in order to determine its precision and parameters of the transformation between two coordinate systems (Cartesian and polar) in which measurements are made. A new approach consists in introducing a special preliminary transformation of scanned data for nonlinear distortion elimination. Coefficients of this transformation are obtained by processing the artificial straight line data measurements. Algorithms of cross center determining, two-dimensional interpolation, straight line recognition and functional minimizing have been improved. Additional testing of scanned data and of the results of their processing have been introduced. Thus precision improvement has been achieved upto 2 μm over the total scanning range

  11. A sulphur abundance study of NGC 300 by an empirical calibration method

    CERN Document Server

    Christensen, T; Gammelgaard, P; Christensen, Tina; Petersen, Lars; Gammelgaard, Peter

    1996-01-01

    We propose an empirical sulphur abundance determination method based on the strong sulphur emission lines, [S II] 6716, 6731 and [S III] 9069, 9531 in H II regions. From a compilation of literature data we have made a calibration of sulphur abundance versus ([S II] + [S III])/Hbeta, similar to what has been widely used for the more easily observable iso-electronic element oxygen. This enables abundance determinations in extragalactic H II regions without measurements of weak temperature sensitive lines for use in model calculations. As a first application of the empirical calibration 15 spectra covering the wavelength range 3650-10000 AA have been obtained of H II regions at various galactocentric distances in the spiral galaxy NGC 300, by employing specially designed multiaperture slitmasks which allow simultaneous observations of several H II regions. Sulphur and oxygen abundances are determined and an oxygen gradient in agreement with previously published work is found as well as a somewhat steeper sulphur...

  12. Calibration method for measurement of linear nanometric distances by scattered total internal reflection

    International Nuclear Information System (INIS)

    Scattered total internal reflection of visible light is used to measure linear nanometric distance to as small as 10 nm. Specifically, we measure the height of magnetic transducer heads above a rotating glass disk. A breakthrough in the approach to calibration, based on combining the second derivative of the transmittance of the scattered light and parameter fitting, substantially improves the quality of the measurement relative to previous demonstrations of this method. The results agree to 1 nm with an industry-standard three-color interferometer to and including the lowest values measured. The technique in principle remains robust to as low as the zero height. Furthermore the calibration point can be as low as 10 nm, which is especially attractive in practice

  13. Absolute calibration method for fast-streaked, fiber optic light collection, spectroscopy systems.

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, Mark D.; Frogget, Brent (National Security Technologies, Las Vegas, NV); Oliver, Bryan Velten; Maron, Yitzhak (Weizmann Institute of Science, Rehovot, Israel); Droemer, Darryl W. (National Security Technologies, Las Vegas, NV); Crain, Marlon D. (National Security Technologies, Las Vegas, NV)

    2010-04-01

    This report outlines a convenient method to calibrate fast (<1ns resolution) streaked, fiber optic light collection, spectroscopy systems. Such a system is used to collect spectral data on plasmas generated in the A-K gap of electron beam diodes fielded on the RITS-6 accelerator (8-12MV, 140-200kA). On RITS, light is collected through a small diameter (200 micron) optical fiber and recorded on a fast streak camera at the output of 1 meter Czerny-Turner monochromator (F/7 optics). To calibrate such a system, it is necessary to efficiently couple light from a spectral lamp into a 200 micron diameter fiber, split it into its spectral components, with 10 Angstroms or less resolution, and record it on a streak camera with 1ns or less temporal resolution.

  14. Heterodyne interferometry method for calibration of a Soleil-Babinet compensator.

    Science.gov (United States)

    Zhang, Wenjing; Zhang, Zhiwei

    2016-05-20

    A method based on the common-path heterodyne interferometer system is proposed for the calibration of a Soleil-Babinet compensator. In this heterodyne interferometer system, which consists of two acousto-optic modulators, the compensator being calibrated is inserted into the signal path. By using the reference beam as the benchmark and a lock-in amplifier (SR844) as the phase retardation collector, retardations of 0 and λ (one wavelength) can be located accurately, and an arbitrary retardation between 0 and λ can also be measured accurately and continuously. By fitting a straight line to the experimental data, we obtained a linear correlation coefficient (R) of 0.995, which indicates that this system is capable of linear phase detection. The experimental results demonstrate determination accuracies of 0.212° and 0.26° and measurement precisions of 0.054° and 0.608° for retardations of 0 and λ, respectively.

  15. Towards in-vivo K-edge imaging using a new semi-analytical calibration method

    Science.gov (United States)

    Schirra, Carsten; Thran, Axel; Daerr, Heiner; Roessl, Ewald; Proksa, Roland

    2014-03-01

    Flat field calibration methods are commonly used in computed tomography (CT) to correct for system imperfections. Unfortunately, they cannot be applied in energy-resolving CT when using bow-tie filters owing to spectral distortions imprinted by the filter. This work presents a novel semi-analytical calibration method for photon-counting spectral CT systems, which is applicable with a bow-tie filter in place and efficiently compensates pile-up effects at fourfold increased photon flux compared to a previously published method without degradation of image quality. The achieved reduction of the scan time enabled the first K-edge imaging in-vivo. The method employs a calibration measurement with a set of flat sheets of only a single absorber material and utilizes an analytical model to predict the expected photon counts, taking into account factors such as x-ray spectrum and detector response. From the ratios of the measured x-ray intensities and the corresponding simulated photon counts, a look-up table is generated. By use of this look-up table, measured photon-counts can be corrected yielding data in line with the analytical model. The corrected data show low pixel-to-pixel variations and pile-up effects are mitigated. Consequently, operations like material decomposition based on the same analytical model yield accurate results. The method was validated on a experimental spectral CT system equipped with a bow-tie filter in a phantom experiment and an in-vivo animal study. The level of artifacts in the resulting images is considerably lower than in images generated with a previously published method. First in-vivo K-edge images of a rabbit selectively depict vessel occlusion by an ytterbium-based thermoresponsive polymer.

  16. 标校经纬仪航向标定修正方法%Correction method of heading calibration for calibration theodolite

    Institute of Scientific and Technical Information of China (English)

    李淼; 高慧斌

    2011-01-01

    为了准确有效地完成经纬仪航向标定,本文根据标校经纬仪坞内航向标校原理,分析了各单项误差对航向标定的影响,建立了照准差和定向误差同时影响下的航向标定修正模型,给出了具体的修正方法。实验及检测结果表明,用正倒镜法测得的定向误差数值等于定向误差与照准差的差值。文章验证了修正方法的正确性和有效性,规范了坞内航向标定方法,为测量船完成测量任务奠定了基础。%To precisely and effectively complete the heading calibration of a theodolite,this paper analyzes the effect of single error on the heading calibration,and builds a correct model of the heading calibration when the collimating and orientation errors are involved at the same time according to the heading calibration principle.It provides the specific correction and verification methods.Experimental and measurement results indicate that the orientation error measured by positive and inverse pointing methods is equivalent to the error between orientation error and collimating error.The research in this paper proves the feasibility and effectiveness of the correction method and disciplines the method of heading calibration at the dock,which will make sure TTC complete mission successfully.

  17. Method of operational diagnostic state of flow and calculation of calibration Coefficients using artificial neural networks

    Directory of Open Access Journals (Sweden)

    Safarini Osama

    2012-01-01

    Full Text Available An important task of operational management in oil and gas production is the control of fluid flow and technological objects of engineering network (EN. This paper proposed a method for diagnosis of fluid flow measurement and calibration operations. The method is based on the relationship between various parameters of the flow of Engineering Network. To calculate the actual flow rate on other parameters of the flow, such as pressure, temperature, and the parameters that determine the composition of the liquid (oil, it is proposed to use a neural network.

  18. A time-delay calibrated method for cornea hysteresis and intraocular pressure measurement

    Science.gov (United States)

    Wang, Kuo-Jen; Tsai, Che-Liang; Wang, Wai; Hsu, Long; Hsu, Ken-Yuh

    2016-04-01

    The presence of cornea hysteresis (CH) in characterizing the intraocular pressure (IOP) of a human eye deteriorates the accuracy of IOP. To suppress CH, the pressure gauge of a tonometer must be located as close as possible to the cornea. However, this arrangement is unpractical because appropriate working distance to the cornea is required. In this paper, a time-delay calibrated (TDC) method is proposed to counteract the undesired effect of CH in characterizing the IOP. Employing this TDC method, the CH approaches to zero for most eyes measured.

  19. A Rapid Coordinate Transformation Method Applied in Industrial Robot Calibration Based on Characteristic Line Coincidence

    Directory of Open Access Journals (Sweden)

    Bailing Liu

    2016-02-01

    Full Text Available Coordinate transformation plays an indispensable role in industrial measurements, including photogrammetry, geodesy, laser 3-D measurement and robotics. The widely applied methods of coordinate transformation are generally based on solving the equations of point clouds. Despite the high accuracy, this might result in no solution due to the use of ill conditioned matrices. In this paper, a novel coordinate transformation method is proposed, not based on the equation solution but based on the geometric transformation. We construct characteristic lines to represent the coordinate systems. According to the space geometry relation, the characteristic line scan is made to coincide by a series of rotations and translations. The transformation matrix can be obtained using matrix transformation theory. Experiments are designed to compare the proposed method with other methods. The results show that the proposed method has the same high accuracy, but the operation is more convenient and flexible. A multi-sensor combined measurement system is also presented to improve the position accuracy of a robot with the calibration of the robot kinematic parameters. Experimental verification shows that the position accuracy of robot manipulator is improved by 45.8% with the proposed method and robot calibration.

  20. A Rapid Coordinate Transformation Method Applied in Industrial Robot Calibration Based on Characteristic Line Coincidence.

    Science.gov (United States)

    Liu, Bailing; Zhang, Fumin; Qu, Xinghua; Shi, Xiaojia

    2016-01-01

    Coordinate transformation plays an indispensable role in industrial measurements, including photogrammetry, geodesy, laser 3-D measurement and robotics. The widely applied methods of coordinate transformation are generally based on solving the equations of point clouds. Despite the high accuracy, this might result in no solution due to the use of ill conditioned matrices. In this paper, a novel coordinate transformation method is proposed, not based on the equation solution but based on the geometric transformation. We construct characteristic lines to represent the coordinate systems. According to the space geometry relation, the characteristic line scan is made to coincide by a series of rotations and translations. The transformation matrix can be obtained using matrix transformation theory. Experiments are designed to compare the proposed method with other methods. The results show that the proposed method has the same high accuracy, but the operation is more convenient and flexible. A multi-sensor combined measurement system is also presented to improve the position accuracy of a robot with the calibration of the robot kinematic parameters. Experimental verification shows that the position accuracy of robot manipulator is improved by 45.8% with the proposed method and robot calibration. PMID:26901203

  1. A Rapid Coordinate Transformation Method Applied in Industrial Robot Calibration Based on Characteristic Line Coincidence.

    Science.gov (United States)

    Liu, Bailing; Zhang, Fumin; Qu, Xinghua; Shi, Xiaojia

    2016-02-18

    Coordinate transformation plays an indispensable role in industrial measurements, including photogrammetry, geodesy, laser 3-D measurement and robotics. The widely applied methods of coordinate transformation are generally based on solving the equations of point clouds. Despite the high accuracy, this might result in no solution due to the use of ill conditioned matrices. In this paper, a novel coordinate transformation method is proposed, not based on the equation solution but based on the geometric transformation. We construct characteristic lines to represent the coordinate systems. According to the space geometry relation, the characteristic line scan is made to coincide by a series of rotations and translations. The transformation matrix can be obtained using matrix transformation theory. Experiments are designed to compare the proposed method with other methods. The results show that the proposed method has the same high accuracy, but the operation is more convenient and flexible. A multi-sensor combined measurement system is also presented to improve the position accuracy of a robot with the calibration of the robot kinematic parameters. Experimental verification shows that the position accuracy of robot manipulator is improved by 45.8% with the proposed method and robot calibration.

  2. An optimization-based method for geometrical calibration in cone-beam CT without dedicated phantoms

    Science.gov (United States)

    Panetta, D.; Belcari, N.; DelGuerra, A.; Moehrs, S.

    2008-07-01

    In this paper we present a new method for the determination of geometrical misalignments in cone-beam CT scanners, from the analysis of the projection data of a generic object. No a priori knowledge of the object shape and positioning is required. We show that a cost function, which depends on the misalignment parameters, can be defined using the projection data and that such a cost function has a local minimum in correspondence to the actual parameters of the system. Hence, the calibration of the scanner can be carried out by minimizing the cost function using standard optimization techniques. The method is developed for a particular class of 3D object functions, for which the redundancy of the fan beam sinogram in the transaxial midplane can be extended to cone-beam projection data, even at wide cone angles. The method has an approximated validity for objects which do not belong to that class; in that case, a suitable subset of the projection data can be selected in order to compute the cost function. We show by numerical simulations that our method is capable to determine with high accuracy the most critical misalignment parameters of the scanner, i.e., the transversal shift and the skew of the detector. Additionally, the detector slant can be determined. Other parameters such as the detector tilt, the longitudinal shift and the error in the source-detector distance cannot be determined with our method, as the proposed cost function has a very weak dependence on them. However, due to the negligible influence of these latter parameters in the reconstructed image quality, they can be kept fixed at estimated values in both calibration and reconstruction processes without compromising the final result. A trade-off between computational cost and calibration accuracy must be considered when choosing the data subset used for the computation of the cost function. Results on real data of a mouse femur as obtained with a small animal micro-CT are shown as well, proving

  3. Calibration method for division of focal plane polarimeters in the optical and near-infrared regime

    Science.gov (United States)

    York, Timothy; Gruev, Viktor

    2011-06-01

    Advances in nanofabrication allow for the creation of metallic nanowires acting as linear polarizers in the visible and near infrared regime. The monolithic integration of silicon detectors and pixelated nanowire metallic polarization filters allows for an efficient realization of high resolution polarization imaging sensors. These silicon sensors, known as division of focal plane polarimeters, capture polarization information of the imaged environment from ~400nm to 1050nm wavelength. The performance of the polarization sensor can be degraded by both irregularities in the fabrication of the nanowires and possible misalignment errors during the final deposition of the optical nanowire filters on the surface of the imaging sensor. In addition, electronic offsets due to the readout circuitry, electronic crosstalk, and optical crosstalk will also negatively affect the quality of the polarization information. Partial compensation for many of these post-fabrication errors can be accomplished through the use of a camera calibration routine. This paper will describe one such routine, and show how its application can increase the quality of measurements in both the degree of linear polarization and angle of polarization in the visible spectrum. The imaging array of the division of focal plane polarimeter is segmented into two by two blocks of superpixels. The calibration method chooses one of the four pixels as a reference, and then a gain and offset for each of the remaining three is computed based on this reference. The output is a calibration matrix for each pixel in the image array.

  4. Dependence of core heating properties on heating pulse duration and intensity

    Science.gov (United States)

    Johzaki, Tomoyuki; Nagatomo, Hideo; Sunahara, Atsushi; Cai, Hongbo; Sakagami, Hitoshi; Mima, Kunioki

    2009-11-01

    In the cone-guiding fast ignition, an imploded core is heated by the energy transport of fast electrons generated by the ultra-intense short-pulse laser at the cone inner surface. The fast core heating (˜800eV) has been demonstrated at integrated experiments with GEKKO-XII+ PW laser systems. As the next step, experiments using more powerful heating laser, FIREX, have been started at ILE, Osaka university. In FIREX-I (phase-I of FIREX), our goal is the demonstration of efficient core heating (Ti ˜ 5keV) using a newly developed 10kJ LFEX laser. In the first integrated experiments, the LFEX laser is operated with low energy mode (˜0.5kJ/4ps) to validate the previous GEKKO+PW experiments. Between the two experiments, though the laser energy is similar (˜0.5kJ), the duration is different; ˜0.5ps in the PW laser and ˜ 4ps in the LFEX laser. In this paper, we evaluate the dependence of core heating properties on the heating pulse duration on the basis of integrated simulations with FI^3 (Fast Ignition Integrated Interconnecting) code system.

  5. High-temperature potentiometry: modulated response of ion-selective electrodes during heat pulses.

    Science.gov (United States)

    Chumbimuni-Torres, Karin Y; Thammakhet, Chongdee; Galik, Michal; Calvo-Marzal, Percy; Wu, Jie; Bakker, Eric; Flechsig, Gerd-Uwe; Wang, Joseph

    2009-12-15

    The concept of locally heated polymeric membrane potentiometric sensors is introduced here for the first time. This is accomplished in an all solid state sensor configuration, utilizing poly(3-octylthiophene) as the intermediate layer between the ion-selective membrane and underlying substrate that integrates the heating circuitry. Temperature pulse potentiometry (TPP) gives convenient peak-shaped analytical signals and affords an additional dimension with these sensors. Numerous advances are envisioned that will benefit the field. The heating step is shown to give an increase in the slope of the copper-selective electrode from 31 to 43 mV per 10-fold activity change, with a reproducibility of the heated potential pulses of 1% at 10 microM copper levels and a potential drift of 0.2 mV/h. Importantly, the magnitude of the potential pulse upon heating the electrode changes as a function of the copper activity, suggesting an attractive way for differential measurement of these devices. The heat pulse is also shown to decrease the detection limit by half an order of magnitude.

  6. Thermal Response of Tritiated Co-deposits from JET and TFTR to Transient Heat Pulses

    Energy Technology Data Exchange (ETDEWEB)

    C.H. Skinner; N. Bekrisl; J.P. Coad; C.A. Gentile; A. Hassanein; R. Reiswig; S. Willms

    2002-05-30

    High heat flux interactions with plasma-facing components have been studied at microscopic scales. The beam from a continuous wave neodymium laser was scanned at high speed over the surface of graphite and carbon fiber composite tiles that had been retrieved from TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) after D-T plasma operations. The tiles have a surface layer of amorphous hydrogenated carbon that was co-deposited during plasma operations, and laser scanning has released more than 80% of the co-deposited tritium. The temperature rise of the co-deposit was much higher than that of the manufactured material and showed an extended time history. The peak temperature varied dramatically (e.g., 1,436 C compared to >2,300 C), indicating strong variations in the thermal conductivity to the substrate. A digital microscope imaged the co-deposit before, during, and after the interaction with the laser and revealed 100-micron scale hot spots during the interaction. Heat pulse durations of order 100 ms resulted in brittle destruction and material loss from the surface, whilst a duration of =10 ms showed minimal changes to the co-deposit. These results show that reliable predictions for the response of deposition areas to off-normal events such as ELMs (edge-localized modes) and disruptions in next-step devices need to be based on experiments with tokamak generated co-deposits.

  7. Calibration of the laser induced pressure pulse method when using a semiconducting electrode as the laser target

    International Nuclear Information System (INIS)

    Space charge distributions can directly be qualitatively estimated from a laser induced pressure pulse (LIPP) signal. To obtain precise quantitative space charge density, calibration of the LIPP method is necessary which requires an ideal measured signal. However, when a carbon loaded polymer electrode is used as the laser target, a long signal tail can be found. The cause of the signal tail is analyzed in this study and two methods are proposed to correct the experimental signals. According to the calibration procedure introduced, space charge density is obtained respectively by using the two correction methods. Finally, the calculated results are compared and the validity of the calibration and correction methods is confirmed. The correction and calibration procedures proposed can be extended to piezoelectric induced pressure pulse and pulsed electroacoustic methods. (paper)

  8. Standard Test Method for Calibration of Primary Non-Concentrator Terrestrial Photovoltaic Reference Cells Using a Tabular Spectrum

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This test method is intended to be used for calibration and characterization of primary terrestrial photovoltaic reference cells to a desired reference spectral irradiance distribution, such as Tables G173. The recommended physical requirements for these reference cells are described in Specification E1040. Reference cells are principally used in the determination of the electrical performance of photovoltaic devices. 1.2 Primary photovoltaic reference cells are calibrated in natural sunlight using the relative spectral response of the cell, the relative spectral distribution of the sunlight, and a tabulated reference spectral irradiance distribution. 1.3 This test method requires the use of a pyrheliometer that is calibrated according to Test Method E816, which requires the use of a pyrheliometer that is traceable to the World Radiometric Reference (WRR). Therefore, reference cells calibrated according to this test method are traceable to the WRR. 1.4 This test method is a technique that may be used ...

  9. Calibration coefficient of reference brachytherapy ionization chamber using analytical and Monte Carlo methods.

    Science.gov (United States)

    Kumar, Sudhir; Srinivasan, P; Sharma, S D

    2010-06-01

    A cylindrical graphite ionization chamber of sensitive volume 1002.4 cm(3) was designed and fabricated at Bhabha Atomic Research Centre (BARC) for use as a reference dosimeter to measure the strength of high dose rate (HDR) (192)Ir brachytherapy sources. The air kerma calibration coefficient (N(K)) of this ionization chamber was estimated analytically using Burlin general cavity theory and by the Monte Carlo method. In the analytical method, calibration coefficients were calculated for each spectral line of an HDR (192)Ir source and the weighted mean was taken as N(K). In the Monte Carlo method, the geometry of the measurement setup and physics related input data of the HDR (192)Ir source and the surrounding material were simulated using the Monte Carlo N-particle code. The total photon energy fluence was used to arrive at the reference air kerma rate (RAKR) using mass energy absorption coefficients. The energy deposition rates were used to simulate the value of charge rate in the ionization chamber and N(K) was determined. The Monte Carlo calculated N(K) agreed within 1.77 % of that obtained using the analytical method. The experimentally determined RAKR of HDR (192)Ir sources, using this reference ionization chamber by applying the analytically estimated N(K), was found to be in agreement with the vendor quoted RAKR within 1.43%.

  10. Cloned plasmid DNA fragments as calibrators for controlling GMOs: different real-time duplex quantitative PCR methods.

    Science.gov (United States)

    Taverniers, Isabel; Van Bockstaele, Erik; De Loose, Marc

    2004-03-01

    Analytical real-time PCR technology is a powerful tool for implementation of the GMO labeling regulations enforced in the EU. The quality of analytical measurement data obtained by quantitative real-time PCR depends on the correct use of calibrator and reference materials (RMs). For GMO methods of analysis, the choice of appropriate RMs is currently under debate. So far, genomic DNA solutions from certified reference materials (CRMs) are most often used as calibrators for GMO quantification by means of real-time PCR. However, due to some intrinsic features of these CRMs, errors may be expected in the estimations of DNA sequence quantities. In this paper, two new real-time PCR methods are presented for Roundup Ready soybean, in which two types of plasmid DNA fragments are used as calibrators. Single-target plasmids (STPs) diluted in a background of genomic DNA were used in the first method. Multiple-target plasmids (MTPs) containing both sequences in one molecule were used as calibrators for the second method. Both methods simultaneously detect a promoter 35S sequence as GMO-specific target and a lectin gene sequence as endogenous reference target in a duplex PCR. For the estimation of relative GMO percentages both "delta C(T)" and "standard curve" approaches are tested. Delta C(T) methods are based on direct comparison of measured C(T) values of both the GMO-specific target and the endogenous target. Standard curve methods measure absolute amounts of target copies or haploid genome equivalents. A duplex delta C(T) method with STP calibrators performed at least as well as a similar method with genomic DNA calibrators from commercial CRMs. Besides this, high quality results were obtained with a standard curve method using MTP calibrators. This paper demonstrates that plasmid DNA molecules containing either one or multiple target sequences form perfect alternative calibrators for GMO quantification and are especially suitable for duplex PCR reactions.

  11. [Application of calibration curve method and partial least squares regression analysis to quantitative analysis of nephrite samples using XRF].

    Science.gov (United States)

    Liu, Song; Su, Bo-min; Li, Qing-hui; Gan, Fu-xi

    2015-01-01

    The authors tried to find a method for quantitative analysis using pXRF without solid bulk stone/jade reference samples. 24 nephrite samples were selected, 17 samples were calibration samples and the other 7 are test samples. All the nephrite samples were analyzed by Proton induced X-ray emission spectroscopy (PIXE) quantitatively. Based on the PIXE results of calibration samples, calibration curves were created for the interested components/elements and used to analyze the test samples quantitatively; then, the qualitative spectrum of all nephrite samples were obtained by pXRF. According to the PIXE results and qualitative spectrum of calibration samples, partial least square method (PLS) was used for quantitative analysis of test samples. Finally, the results of test samples obtained by calibration method, PLS method and PIXE were compared to each other. The accuracy of calibration curve method and PLS method was estimated. The result indicates that the PLS method is the alternate method for quantitative analysis of stone/jade samples. PMID:25993858

  12. [Application of calibration curve method and partial least squares regression analysis to quantitative analysis of nephrite samples using XRF].

    Science.gov (United States)

    Liu, Song; Su, Bo-min; Li, Qing-hui; Gan, Fu-xi

    2015-01-01

    The authors tried to find a method for quantitative analysis using pXRF without solid bulk stone/jade reference samples. 24 nephrite samples were selected, 17 samples were calibration samples and the other 7 are test samples. All the nephrite samples were analyzed by Proton induced X-ray emission spectroscopy (PIXE) quantitatively. Based on the PIXE results of calibration samples, calibration curves were created for the interested components/elements and used to analyze the test samples quantitatively; then, the qualitative spectrum of all nephrite samples were obtained by pXRF. According to the PIXE results and qualitative spectrum of calibration samples, partial least square method (PLS) was used for quantitative analysis of test samples. Finally, the results of test samples obtained by calibration method, PLS method and PIXE were compared to each other. The accuracy of calibration curve method and PLS method was estimated. The result indicates that the PLS method is the alternate method for quantitative analysis of stone/jade samples.

  13. Application of calibration standardization method to the analysis of diuretic pharmaceutical herbs

    International Nuclear Information System (INIS)

    Calibration standardization of X-ray fluorescence method was carried out for the determination of the anorganic contents in diuretic herbs as called Folia Betulae, Stylus Maydis, Flores Verbasci, Equisetum Arvense and Flos Helichrysi, growing in Turkey. These herbs are widely used in pharmacy and public health for kidney disease therapy. Herb samples were steeped in the water and mixed through the pure cellulose, then pelletized in the intermediate thickness. An annular source of 109Cd (3.7 MBq) was used for excitation of fluorescent K lines of elements lying between potassium and zirconium. Toxic elements in considerable amounts were not found. (author)

  14. A New Method to Calibrate Attachment Angles of Data Loggers in Swimming Sharks

    Directory of Open Access Journals (Sweden)

    Shizuka Kawatsu

    2010-01-01

    Full Text Available Recently, animal-borne accelerometers have been used to record the pitch angle of aquatic animals during swimming. When evaluating pitch angle, it is necessary to consider a discrepancy between the angle of an accelerometer and the long axis of an animal. In this study, we attached accelerometers to 17 free-ranging scalloped hammerhead shark (Sphyrna lewini pups from Kaneohe Bay, Hawaii. Although there are methods to calibrate attachment angles of accelerometers, we confirmed that previous methods were not applicable for hammerhead pups. According to raw data, some sharks ascended with a negative angle, which differs from tank observations of captive sharks. In turn, we developed a new method to account for this discrepancy in swimming sharks by estimating the attachment angle from the relationship between vertical speed (m/s and pitch angle obtained by each accelerometer. The new method can be utilized for field observation of a wide range of species.

  15. A New Method to Calibrate Attachment Angles of Data Loggers in Swimming Sharks

    Science.gov (United States)

    Kawatsu, Shizuka; Sato, Katsufumi; Watanabe, Yuuki; Hyodo, Susumu; Breves, Jason P.; Fox, Bradley K.; Grau, E. Gordon; Miyazaki, Nobuyuki

    2009-12-01

    Recently, animal-borne accelerometers have been used to record the pitch angle of aquatic animals during swimming. When evaluating pitch angle, it is necessary to consider a discrepancy between the angle of an accelerometer and the long axis of an animal. In this study, we attached accelerometers to 17 free-ranging scalloped hammerhead shark ( Sphyrna lewini) pups from Kaneohe Bay, Hawaii. Although there are methods to calibrate attachment angles of accelerometers, we confirmed that previous methods were not applicable for hammerhead pups. According to raw data, some sharks ascended with a negative angle, which differs from tank observations of captive sharks. In turn, we developed a new method to account for this discrepancy in swimming sharks by estimating the attachment angle from the relationship between vertical speed (m/s) and pitch angle obtained by each accelerometer. The new method can be utilized for field observation of a wide range of species.

  16. A calibration method for optical trap force by use of electrokinetic phenomena

    Institute of Scientific and Technical Information of China (English)

    Youli Yu; Zhenxi Zhang; Xiaolin Zhang

    2006-01-01

    @@ An experimental method for calibration of optical trap force upon cells by use of electrokinetic phenomena is demonstrated.An electronkinetic sample chamber system (ESCS) is designed instead of a common sample chamber and a costly automatism stage,thus the experimental setup is simpler and cheaper.Experiments indicate that the range of the trap force measured by this method is piconewton and sub-piconewton,which makes it fit for study on non-damage interaction between light and biological particles with optical tweezers especially.Since this method is relevant to particle electric charge,by applying an alternating electric field,the new method may overcome the problem of correcting drag force and allow us to measure simultaneously optical trap stiffness and particle electric charge.

  17. Calibration period dependence of extreme flood estimations (with a model-based flood frequency method)

    Science.gov (United States)

    Brigode, P.; Bernardara, P.; Paquet, E.; Gailhard, J.; Garavaglia, F.; Ribstein, P.; Micovic, Z.

    2013-12-01

    Extreme floods estimation methods are developed since many years within the hydrological and statistical communities. More recently, approaches based on the statistical analysis of flood streamflow samples simulated by rainfall-runoff models which are forced by simulated rainfall spread in the scientific literature. These approaches, called stochastic simulation methods, are typically composed by a probabilistic rainfall model and a rainfall-runoff model. Each of these two models are calibrated over observed hydrometeorological series such as daily precipitation series for the probabilistic rainfall models or such as daily streamflow, precipitation and temperature series for the rainfall-runoff models. Since extreme flood observations are by definition particularly rare, the validation of the proposed extreme flood estimations is one of the main critical issues, whatever the method - statistical or physically-based - used. Moreover, the observed hydrometeorological series used for the calibration of the stochastic simulation methods may be subject to significant variability over time, due to global climate oscillations such as El Niño Southern Oscillations for example. If the estimation of total involved uncertainty is a difficult task, investigating to what extent the proposed extreme flood values are dependent on the calibration period is an interesting first step. The general aim of this study is to propose a methodology for performing a sensitivity analysis of extreme flood estimations to the variability of observed series used for the model calibrations in a stochastic simulation framework. The methodology proposed is based on the nonparametric bootstrap concept and consists to perform a set of block-bootstrap experiments, thus generating different sets of observed series sub-samples. The generated observed series sub-samples are then used for the calibration of the different models considered within the stochastic simulation method. The main originality of

  18. Direct liquid deposition calibration method for trace cyclotrimethylenetrinitramine using thermal desorption instrumentation.

    Science.gov (United States)

    Field, Christopher R; Lubrano, Adam L; Rogers, Duane A; Giordano, Braden C; Collins, Greg E

    2013-03-22

    A simple method for establishing calibration curves with sorbent-filled thermal desorption tubes has been demonstrated for nitroaromatic and nitramine vapor samples using a thermal desorption system with a cooled inlet system (TDS-CIS), which was coupled to a gas chromatograph (GC) with an electron capture detector (ECD). The method relies upon the direct liquid deposition of standard solutions onto the glass frit at the head of sorbent-filled thermal desorption tubes. Linear calibration results and ideal system conditions for the TDS-CIS-GC-ECD were established for mixtures containing both cyclotrimethylenetrinitramine, a.k.a. RDX, and 2,4,6-trinitrotoluene (TNT). Because of the chemical characteristics of RDX, a higher TDS-CIS flow rate relative to the optimized approach for TNT was required for efficient RDX desorption. Simultaneous quantitation of TNT and RDX using the direct liquid deposition method with optimized instrumentation parameters for RDX were compared to results from a standard split/splitless GC inlet and a CIS. PMID:23415141

  19. Comparing Two Different Methods of Preferential Flow Simulation, Using Calibration Constrained Monte Carlo Uncertainty analysis

    Science.gov (United States)

    Schirmer, M.; Ghasemizade, M.; Radny, D.

    2014-12-01

    Many different methods and approaches have been suggested for simulation of preferential flows. However, most of these methods have been tested in lab scales where boundary conditions and material properties are known and under control. The focus of this study is to compare two different approaches for simulating preferential flows in a weighing lysimeter where the scale of simulation is closer to field scales than simulations done in labs. To do so, we applied dual permeability and spatially distributed heterogeneity as two competitive approaches for simulating slow and rapid flow out of a lysimeter. While the dual permeability approach assumes that there is a structure among soil aggregates and that can be captured as a fraction of the porosity, the other method attributes the existence of preferential flows to heterogeneity distributed within the domain. The two aforementioned approaches were used in order to simulate daily recharge values of a lysimeter. The analysis included a calibration phase, which started from March 2012 until March 2013, and a validation phase which lasted a year following the calibration period. The simulations were performed based on the numerical and 3-D physically based model HydroGeoSphere. The nonlinear uncertainty analysis of the results indicate that they are comparable.

  20. A review of neutron scattering correction for the calibration of neutron survey meters using the shadow cone method

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Sang In; Kim, Bong Hwan; Kim, Jang Lyul; Lee, Jung Il [Health Physics Team, Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-12-15

    The calibration methods of neutron-measuring devices such as the neutron survey meter have advantages and disadvantages. To compare the calibration factors obtained by the shadow cone method and semi-empirical method, 10 neutron survey meters of five different types were used in this study. This experiment was performed at the Korea Atomic Energy Research Institute (KAERI; Daejeon, South Korea), and the calibration neutron fields were constructed using a {sup 252}Californium ({sup 252}Cf) neutron source, which was positioned in the center of the neutron irradiation room. The neutron spectra of the calibration neutron fields were measured by a europium-activated lithium iodide scintillator in combination with KAERI's Bonner sphere system. When the shadow cone method was used, 10 single moderator-based survey meters exhibited a smaller calibration factor by as much as 3.1 - 9.3% than that of the semi-empirical method. This finding indicates that neutron survey meters underestimated the scattered neutrons and attenuated neutrons (i.e., the total scatter corrections). This underestimation of the calibration factor was attributed to the fact that single moderator-based survey meters have an under-ambient dose equivalent response in the thermal or thermal-dominant neutron field. As a result, when the shadow cone method is used for a single moderator-based survey meter, an additional correction and the International Organization for Standardization standard 8529-2 for room-scattered neutrons should be considered.

  1. High Precision Astrometric Millimeter VLBI Using a New Method for Atmospheric Calibration

    CERN Document Server

    Rioja, Maria J

    2011-01-01

    We describe a new method which achieves high precision Very Long Baseline Interferometry (VLBI) astrometry in observations at millimeter wavelengths. It combines fast frequency-switching observations, to correct for the dominant non-dispersive tropospheric fluctuations, with slow source-switching observations, for the remaining ionospheric dispersive terms. We call this method Source-Frequency Phase Referencing. Provided that the switching cycles match the properties of the propagation media, one can recover the source astrometry. We present an analytic description of the two-step calibration strategy, along with an error analysis to characterize its performance. Also, we provide observational demonstrations of a successful application with observations using the Very Long Baseline Array at 86 GHz of the pairs of sources 3C274 & 3C273 and 1308+326 & 1308+328, under various conditions. We conclude that this method is widely applicable to millimeter VLBI observations of many target sources, and unique i...

  2. Automatic Calibration Method of Voxel Size for Cone-beam 3D-CT Scanning System

    CERN Document Server

    Yang, Min; Liu, Yipeng; Men, Fanyong; Li, Xingdong; Liu, Wenli; Wei, Dongbo

    2013-01-01

    For cone-beam three-dimensional computed tomography (3D-CT) scanning system, voxel size is an important indicator to guarantee the accuracy of data analysis and feature measurement based on 3D-CT images. Meanwhile, the voxel size changes with the movement of the rotary table along X-ray direction. In order to realize the automatic calibration of the voxel size, a new easily-implemented method is proposed. According to this method, several projections of a spherical phantom are captured at different imaging positions and the corresponding voxel size values are calculated by non-linear least square fitting. Through these interpolation values, a linear equation is obtained, which reflects the relationship between the rotary table displacement distance from its nominal zero position and the voxel size. Finally, the linear equation is imported into the calibration module of the 3D-CT scanning system, and when the rotary table is moving along X-ray direction, the accurate value of the voxel size is dynamically expo...

  3. Generic precise augmented reality guiding system and its calibration method based on 3D virtual model.

    Science.gov (United States)

    Liu, Miao; Yang, Shourui; Wang, Zhangying; Huang, Shujun; Liu, Yue; Niu, Zhenqi; Zhang, Xiaoxuan; Zhu, Jigui; Zhang, Zonghua

    2016-05-30

    Augmented reality system can be applied to provide precise guidance for various kinds of manual works. The adaptability and guiding accuracy of such systems are decided by the computational model and the corresponding calibration method. In this paper, a novel type of augmented reality guiding system and the corresponding designing scheme are proposed. Guided by external positioning equipment, the proposed system can achieve high relative indication accuracy in a large working space. Meanwhile, the proposed system is realized with a digital projector and the general back projection model is derived with geometry relationship between digitized 3D model and the projector in free space. The corresponding calibration method is also designed for the proposed system to obtain the parameters of projector. To validate the proposed back projection model, the coordinate data collected by a 3D positioning equipment is used to calculate and optimize the extrinsic parameters. The final projecting indication accuracy of the system is verified with subpixel pattern projecting technique. PMID:27410124

  4. An Accurate Calibration Method Based on Velocity in a Rotational Inertial Navigation System.

    Science.gov (United States)

    Zhang, Qian; Wang, Lei; Liu, Zengjun; Feng, Peide

    2015-01-01

    Rotation modulation is an effective method to enhance the accuracy of an inertial navigation system (INS) by modulating the gyroscope drifts and accelerometer bias errors into periodically varying components. The typical RINS drives the inertial measurement unit (IMU) rotation along the vertical axis and the horizontal sensors' errors are modulated, however, the azimuth angle error is closely related to vertical gyro drift, and the vertical gyro drift also should be modulated effectively. In this paper, a new rotation strategy in a dual-axis rotational INS (RINS) is proposed and the drifts of three gyros could be modulated, respectively. Experimental results from a real dual-axis RINS demonstrate that the maximum azimuth angle error is decreased from 0.04° to less than 0.01° during 1 h. Most importantly, the changing of rotation strategy leads to some additional errors in the velocity which is unacceptable in a high-precision INS. Then the paper studies the basic reason underlying horizontal velocity errors in detail and a relevant new calibration method is designed. Experimental results show that after calibration and compensation, the fluctuation and stages in the velocity curve disappear and velocity precision is improved. PMID:26225983

  5. The research on calibration methods of dual-CCD laser three-dimensional human face scanning system

    Science.gov (United States)

    Wang, Jinjiang; Chang, Tianyu; Ge, Baozhen; Tian, Qingguo; Yang, Fengting; Shi, Shendong

    2013-09-01

    In this paper, on the basis of considering the performance advantages of two-step method, we combines the stereo matching of binocular stereo vision with active laser scanning to calibrate the system. Above all, we select a reference camera coordinate system as the world coordinate system and unity the coordinates of two CCD cameras. And then obtain the new perspective projection matrix (PPM) of each camera after the epipolar rectification. By those, the corresponding epipolar equation of two cameras can be defined. So by utilizing the trigonometric parallax method, we can measure the space point position after distortion correction and achieve stereo matching calibration between two image points. Experiments verify that this method can improve accuracy and system stability is guaranteed. The stereo matching calibration has a simple process with low-cost, and simplifies regular maintenance work. It can acquire 3D coordinates only by planar checkerboard calibration without the need of designing specific standard target or using electronic theodolite. It is found that during the experiment two-step calibration error and lens distortion lead to the stratification of point cloud data. The proposed calibration method which combining active line laser scanning and binocular stereo vision has the both advantages of them. It has more flexible applicability. Theory analysis and experiment shows the method is reasonable.

  6. Online Calibration Methods for the DINA Model with Independent Attributes in CD-CAT

    Science.gov (United States)

    Chen, Ping; Xin, Tao; Wang, Chun; Chang, Hua-Hua

    2012-01-01

    Item replenishing is essential for item bank maintenance in cognitive diagnostic computerized adaptive testing (CD-CAT). In regular CAT, online calibration is commonly used to calibrate the new items continuously. However, until now no reference has publicly become available about online calibration for CD-CAT. Thus, this study investigates the…

  7. Absolute calibration of OH density in a nanosecond pulsed plasma filament in atmospheric pressure He-H2O: comparison of independent calibration methods

    Science.gov (United States)

    Verreycken, T.; van der Horst, R. M.; Sadeghi, N.; Bruggeman, P. J.

    2013-11-01

    The absolute density of OH radicals generated in a nanosecond pulsed filamentary discharge in atmospheric pressure He +0.84% H2O is measured independently by UV absorption and laser induced fluorescence (LIF) calibrated with Rayleigh scattering. For the calibration of LIF with Rayleigh scattering, two LIF models, with six levels and four levels, are studied to investigate the influence of the rotational and vibrational energy transfers. In addition, a chemical model is used to deduce the OH density in the afterglow from the relative LIF intensity as function of time. The different models show good correspondence and by comparing these different methods, the accuracy and the effect of assumptions on the obtained OH density are discussed in detail. This analysis includes an analysis of the sensitivity to parameters used in the LIF models.

  8. Calibration of the HSPF model with a new coupled FTABLE generation method

    Institute of Scientific and Technical Information of China (English)

    Jing Zhang; Mark Ross; Ken Trout; Demin Zhou

    2009-01-01

    The hydrological simulation program FORTRAN (HSPF) is a comprehensive watershed model designed to simulate water quantity and quality processes.It is used widely throughout the world.Calculating discharge from a stream reach by HSPF is based mainly on function tables (FTABLEs),which describe the relationship between surface area,stream stage,volume,and discharge.The traditional method of FTABLE generation (using general stream cross-sections and the Manning equation or other discharge relationships) can be time-consuming and inaccurate when there are limited calibration stations and survey data.Recent insights into generalized coupled stage/storage and stage/discharge relationships,however,offer the potential to improve both the speed and accuracy of compiling FTABLEs and thus HSPF models.This study tested the application of these insights in generating FTABLEs.The study domain included 18 gauging stations in a coastal plain environment on the Peace River watershed in West-Central Florida.In the calibration of this model,wetlands were treated as reaches in HSPF with storage-attenuation characteristics.Over the simulation period,the modeled daily flow and stage correlated well with observed data at all ganging stations along the Peace River.The Nash-Sutcliffe efficiency and correlation coefficient computed using observed and simulated daily flows were 0.90 and 0.91,respectively,at the Peace River outlet.Rigorous testing found that the new system for calibrating the FTABLEs improved the model predictive ability and efficiency.Uncertainty in un-calibrated station performance was also reduced.The model parameters obtained in this study could potentially serve as reference values for model application in similar climatic regions.They may also have particular relevance in disaster management,as the simulation period extended over the hurricane season of 2004,and the model domain was within a high hurricane impact zone.The possible effects of hurricanes on discharge are

  9. A new method for the absolute radiance calibration for UV/vis measurements of scattered sun light

    Directory of Open Access Journals (Sweden)

    T. Wagner

    2015-05-01

    Full Text Available Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds and the short wave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV/vis instruments that measure the spectrally resolved sky radiance, like for example zenith sky Differential Optical Absorption Spectroscopy (DOAS- instruments or Multi-AXis (MAX- DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method clear sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about <7%. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements is constant and known.

  10. A new method for the absolute radiance calibration for UV/vis measurements of scattered sun light

    Science.gov (United States)

    Wagner, T.; Beirle, S.; Dörner, S.; Penning de Vries, M.; Remmers, J.; Rozanov, A.; Shaiganfar, R.

    2015-05-01

    Absolute radiometric calibrations are important for measurements of the atmospheric spectral radiance. Such measurements can be used to determine actinic fluxes, the properties of aerosols and clouds and the short wave energy budget. Conventional calibration methods in the laboratory are based on calibrated light sources and reflectors and are expensive, time consuming and subject to relatively large uncertainties. Also, the calibrated instruments might change during transport from the laboratory to the measurement sites. Here we present a new calibration method for UV/vis instruments that measure the spectrally resolved sky radiance, like for example zenith sky Differential Optical Absorption Spectroscopy (DOAS-) instruments or Multi-AXis (MAX-) DOAS instruments. Our method is based on the comparison of the solar zenith angle dependence of the measured zenith sky radiance with radiative transfer simulations. For the application of our method clear sky measurements during periods with almost constant aerosol optical depth are needed. The radiative transfer simulations have to take polarisation into account. We show that the calibration results are almost independent from the knowledge of the aerosol optical properties and surface albedo, which causes a rather small uncertainty of about <7%. For wavelengths below about 330 nm it is essential that the ozone column density during the measurements is constant and known.

  11. A Novel Error Model of Optical Systems and an On-Orbit Calibration Method for Star Sensors

    Directory of Open Access Journals (Sweden)

    Shuang Wang

    2015-12-01

    Full Text Available In order to improve the on-orbit measurement accuracy of star sensors, the effects of image-plane rotary error, image-plane tilt error and distortions of optical systems resulting from the on-orbit thermal environment were studied in this paper. Since these issues will affect the precision of star image point positions, in this paper, a novel measurement error model based on the traditional error model is explored. Due to the orthonormal characteristics of image-plane rotary-tilt errors and the strong nonlinearity among these error parameters, it is difficult to calibrate all the parameters simultaneously. To solve this difficulty, for the new error model, a modified two-step calibration method based on the Extended Kalman Filter (EKF and Least Square Methods (LSM is presented. The former one is used to calibrate the main point drift, focal length error and distortions of optical systems while the latter estimates the image-plane rotary-tilt errors. With this calibration method, the precision of star image point position influenced by the above errors is greatly improved from 15.42% to 1.389%. Finally, the simulation results demonstrate that the presented measurement error model for star sensors has higher precision. Moreover, the proposed two-step method can effectively calibrate model error parameters, and the calibration precision of on-orbit star sensors is also improved obviously.

  12. Transient Method for Determining Indoor Chemical Concentrations Based on SPME: Model Development and Calibration.

    Science.gov (United States)

    Cao, Jianping; Xiong, Jianyin; Wang, Lixin; Xu, Ying; Zhang, Yinping

    2016-09-01

    Solid-phase microextraction (SPME) is regarded as a nonexhaustive sampling technique with a smaller extraction volume and a shorter extraction time than traditional sampling techniques and is hence widely used. The SPME sampling process is affected by the convection or diffusion effect along the coating surface, but this factor has seldom been studied. This paper derives an analytical model to characterize SPME sampling for semivolatile organic compounds (SVOCs) as well as for volatile organic compounds (VOCs) by considering the surface mass transfer process. Using this model, the chemical concentrations in a sample matrix can be conveniently calculated. In addition, the model can be used to determine the characteristic parameters (partition coefficient and diffusion coefficient) for typical SPME chemical samplings (SPME calibration). Experiments using SPME samplings of two typical SVOCs, dibutyl phthalate (DBP) in sealed chamber and di(2-ethylhexyl) phthalate (DEHP) in ventilated chamber, were performed to measure the two characteristic parameters. The experimental results demonstrated the effectiveness of the model and calibration method. Experimental data from the literature (VOCs sampled by SPME) were used to further validate the model. This study should prove useful for relatively rapid quantification of concentrations of different chemicals in various circumstances with SPME. PMID:27476381

  13. Linear and Nonlinear Calibration Methods for Predicting Mechanical Properties of Polypropylene Pellets Using Raman Spectroscopy.

    Science.gov (United States)

    Banquet-Terán, Julio; Johnson-Restrepo, Boris; Hernández-Morelo, Alveiro; Ropero, Jorge; Fontalvo-Gomez, Miriam; Romañach, Rodolfo J

    2016-07-01

    A nondestructive and faster methodology to quantify mechanical properties of polypropylene (PP) pellets, obtained from an industrial plant, was developed with Raman spectroscopy. Raman spectra data were obtained from several types of samples such as homopolymer PP, random ethylene-propylene copolymer, and impact ethylene-propylene copolymer. Multivariate calibration models were developed by relating the changes in the Raman spectra to mechanical properties determined by ASTM tests (Young's traction modulus, tensile strength at yield, elongation at yield on traction, and flexural modulus at 1% secant). Several strategies were evaluated to build robust models including the use of preprocessing methods (baseline correction, vector normalization, de-trending, and standard normal variate), selecting the best subset of wavelengths to model property response and discarding irrelevant variables by applying genetic algorithm (GA). Linear multivariable models were investigated such as partial least square regression (PLS) and PLS with genetic algorithm (GA-PLS) while nonlinear models were implemented with artificial neural network (ANN) preceded by GA (GA-ANN). The best multivariate calibration models were obtained when a combination of genetic algorithms and artificial neural network were used on Raman spectral data with relative standard errors (%RSE) from 0.17 to 0.41 for training and 0.42 to 0.88% validation data sets. PMID:27287847

  14. A Single-Vector Force Calibration Method Featuring the Modern Design of Experiments

    Science.gov (United States)

    Parker, P. A.; Morton, M.; Draper, N.; Line, W.

    2001-01-01

    This paper proposes a new concept in force balance calibration. An overview of the state-of-the-art in force balance calibration is provided with emphasis on both the load application system and the experimental design philosophy. Limitations of current systems are detailed in the areas of data quality and productivity. A unique calibration loading system integrated with formal experimental design techniques has been developed and designated as the Single-Vector Balance Calibration System (SVS). This new concept addresses the limitations of current systems. The development of a quadratic and cubic calibration design is presented. Results from experimental testing are compared and contrasted with conventional calibration systems. Analyses of data are provided that demonstrate the feasibility of this concept and provide new insights into balance calibration.

  15. A method for Kinematic Calibration of a Parallel Robot by using one camera in hand and a spherical object

    OpenAIRE

    Traslosheros Michel, Alberto; Sebastian y Zuñiga, Jose Maria; Castillo, Eduardo; Roberti, Flavio; Carelli, Ricardo

    2011-01-01

    The main purpose of robot calibration is the correction of the possible errors in the robot parameters. This paper presents a method for a kinematic calibration of a parallel robot that is equipped with one camera in hand. In order to preserve the mechanical configuration of the robot, the camera is utilized to acquire incremental positions of the end effector from a spherical object that is fixed in the word reference frame. The positions of the end effector are related to incremental posit...

  16. Sediment Core Extrusion Method at Millimeter Resolution Using a Calibrated, Threaded-rod.

    Science.gov (United States)

    Schwing, Patrick T; Romero, Isabel C; Larson, Rebekka A; O'Malley, Bryan J; Fridrik, Erika E; Goddard, Ethan A; Brooks, Gregg R; Hastings, David W; Rosenheim, Brad E; Hollander, David J; Grant, Guy; Mulhollan, Jim

    2016-01-01

    Aquatic sediment core subsampling is commonly performed at cm or half-cm resolution. Depending on the sedimentation rate and depositional environment, this resolution provides records at the annual to decadal scale, at best. An extrusion method, using a calibrated, threaded-rod is presented here, which allows for millimeter-scale subsampling of aquatic sediment cores of varying diameters. Millimeter scale subsampling allows for sub-annual to monthly analysis of the sedimentary record, an order of magnitude higher than typical sampling schemes. The extruder consists of a 2 m aluminum frame and base, two core tube clamps, a threaded-rod, and a 1 m piston. The sediment core is placed above the piston and clamped to the frame. An acrylic sampling collar is affixed to the upper 5 cm of the core tube and provides a platform from which to extract sub-samples. The piston is rotated around the threaded-rod at calibrated intervals and gently pushes the sediment out the top of the core tube. The sediment is then isolated into the sampling collar and placed into an appropriate sampling vessel (e.g., jar or bag). This method also preserves the unconsolidated samples (i.e., high pore water content) at the surface, providing a consistent sampling volume. This mm scale extrusion method was applied to cores collected in the northern Gulf of Mexico following the Deepwater Horizon submarine oil release. Evidence suggests that it is necessary to sample at the mm scale to fully characterize events that occur on the monthly time-scale for continental slope sediments. PMID:27585268

  17. Towards monolithic scintillator based TOF-PET systems: practical methods for detector calibration and operation

    Science.gov (United States)

    Borghi, Giacomo; Tabacchini, Valerio; Schaart, Dennis R.

    2016-07-01

    Gamma-ray detectors based on thick monolithic scintillator crystals can achieve spatial resolutions  PET), the application of monolithic scintillators has so far been hampered by the lengthy and complex procedures needed for position- and time-of-interaction estimation. Here, the algorithms previously developed in our group are revised to make the calibration and operation of a large number of monolithic scintillator detectors in a TOF-PET system practical. In particular, the k-nearest neighbor (k-NN) classification method for x,y-position estimation is accelerated with an algorithm that quickly preselects only the most useful reference events, reducing the computation time for position estimation by a factor of ~200 compared to the previously published k-NN 1D method. Also, the procedures for estimating the DOI and time of interaction are revised to enable full detector calibration by means of fan-beam or flood irradiations only. Moreover, a new technique is presented to allow the use of events in which some of the photosensor pixel values and/or timestamps are missing (e.g. due to dead time), so as to further increase system sensitivity. The accelerated methods were tested on a monolithic scintillator detector specifically developed for clinical PET applications, consisting of a 32 mm  ×  32 mm  ×  22 mm LYSO : Ce crystal coupled to a digital photon counter (DPC) array. This resulted in a spatial resolution of 1.7 mm FWHM, an average DOI resolution of 3.7 mm FWHM, and a CRT of 214 ps. Moreover, the possibility of using events missing the information of up to 16 out of 64 photosensor pixels is shown. This results in only a small deterioration of the detector performance.

  18. A calibration method of Argo floats based on multiple regression analysis

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Argo floats are free-moving floats that report vertical profiles of salinity, temperature and pressure at regular time intervals. These floats give good measurements of temperature and pressure, but salinity measurements may show significant sensor drifting with time. It is found that sensor drifting with time is not purely linear as presupposed by Wong (2003). A new method is developed to calibrate conductivity data measured by Argo floats. In this method, Wong's objective analysis method was adopted to estimate the background climatological salinity field on potential temperature surfaces from nearby historical data in WOD01. Furthermore, temperature and time factors are taken into account, and stepwise regression was used for a time-varying or temperature-varying slope in potential conductivity space to correct the drifting in these profiling float salinity data. The result shows salinity errors using this method are smaller than that of Wong's method, the quantitative and qualitative analysis of the conductivity sensor can be carried out with our method.

  19. Clustered iterative stochastic ensemble method for multi-modal calibration of subsurface flow models

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-05-01

    A novel multi-modal parameter estimation algorithm is introduced. Parameter estimation is an ill-posed inverse problem that might admit many different solutions. This is attributed to the limited amount of measured data used to constrain the inverse problem. The proposed multi-modal model calibration algorithm uses an iterative stochastic ensemble method (ISEM) for parameter estimation. ISEM employs an ensemble of directional derivatives within a Gauss-Newton iteration for nonlinear parameter estimation. ISEM is augmented with a clustering step based on k-means algorithm to form sub-ensembles. These sub-ensembles are used to explore different parts of the search space. Clusters are updated at regular intervals of the algorithm to allow merging of close clusters approaching the same local minima. Numerical testing demonstrates the potential of the proposed algorithm in dealing with multi-modal nonlinear parameter estimation for subsurface flow models. © 2013 Elsevier B.V.

  20. PRESAGE® as a new calibration method for high intensity focused ultrasound therapy

    International Nuclear Information System (INIS)

    High Intensity Focused ultrasound (HIFU) is a non-invasive cancer therapy that makes use of the mainly thermal effects of ultrasound to destroy tissue. In order to achieve reliable treatment planning, it is necessary to characterise the ultrasound source (transducer) and to understand how the wave propagates in tissue and the energy deposition in the focal region. This novel exploratory study investigated how HIFU affects PRESAGE®, an optical phantom used for radiotherapy dosimetry, which is potentially a rapid method of calibrating the transducer. Samples, of two different formulations, were exposed to focused ultrasound and imaged using Optical Computed Tomography. First results showed that, PRESAGE® changes colour on ultrasound exposure (darker green regions were observed) with the alterations being related to the acoustic power and sample composition. Future work will involve quantification of these alterations and understanding how to relate them to the mechanisms of action of HIFU

  1. A Simple Permittivity Calibration Method for GPR-Based Road Pavement Measurements

    Science.gov (United States)

    Eskelinen, Pekka

    2016-09-01

    Cylindrical resonator principle can be used in GPR asphalt quality measurement calibration. This method relies on ordinary drill core samples that are regularly taken from measured road sections, but now only analyzed for dimensions, density and sometimes chemically. If such a drill sample is covered with proper conductive surfaces, a cylindrical cavity resonator is formed. The baseline of the GPR permittivity recordings can so be found by measuring the resonance behaviour of this covered sample, which can later still be used for those traditional analyses. A clear benefit is the resonator's 1-2 GHz frequency range which equals that of common commercial GPR systems. Example results and reference readings from known dielectric material are shown. The obtained uncertainty in this case study is 0.02 units of permittivity, when measuring the same sample repeatedly.

  2. Methods for Optical Calibration of the BigBite Hadron Spectrometer

    CERN Document Server

    Mihovilovic, M; Anderson, B D; Annand, J R M; Averett, T; Camsonne, A; Chan, R W; Chen, J -P; Chirapatpimol, K; de Jager, C W; Gilad, S; Hamilton, D J; Hansen, J -O; Higinbotham, D W; Juang, J; Jiang, X; Jin, G; Korsch, W; LeRose, J J; Lindgren, R A; Liyanage, N; Long, E; Michaels, R; Moffit, B; Monaghan, P; Nelyubin, V; Norum, B E; Piasetzky, E; Qian, X; Qiang, Y; Riordan, S; Ron, G; Rosner, G; Sawatzky, B; Shabestari, M; Shahinyan, A; Shneor, R; Sirca, S; Subedi, R; Sulkosky, V; Watson, J W; Wojtsekhowski, B; Zhang, Y -W

    2012-01-01

    The techniques for optical calibration of Jefferson Lab's large-acceptance magnetic hadron spectrometer, BigBite, have been examined. The most consistent and stable results were obtained by using a method based on singular value decomposition. In spite of the complexity of the optics, the particles' positions and momenta at the target have been precisely reconstructed from the coordinates measured in the detectors by means of a single back-tracing matrix. The technique is applicable to any similar magnetic spectrometer and any particle type. For 0.55 GeV/c protons, we have established the vertex resolution of 1.2 cm, angular resolutions of 7 mrad and 16 mrad (in-plane and out-of-plane, respectively), and a relative momentum resolution of 1.6%.

  3. Differential Binary Encoding Method for Calibrating Image Sensors Based on IOFBs

    Directory of Open Access Journals (Sweden)

    Ángel Cano

    2012-03-01

    Full Text Available Image transmission using incoherent optical fiber bundles (IOFBs requires prior calibration to obtain the spatial in-out fiber correspondence necessary to reconstruct the image captured by the pseudo-sensor. This information is recorded in a Look-Up Table called the Reconstruction Table (RT, used later for reordering the fiber positions and reconstructing the original image. This paper presents a very fast method based on image-scanning using spaces encoded by a weighted binary code to obtain the in-out correspondence. The results demonstrate that this technique yields a remarkable reduction in processing time and the image reconstruction quality is very good compared to previous techniques based on spot or line scanning, for example.

  4. Methods for Optical Calibration of the BigBite Hadron Spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    M. Mihovilovic, K. Allada, B.D. Anderson, J.R.M. Annand, T. Averett, A. Camsonne, R.W. Chan, J.-P. Chen, K. Chirapatpimol, C.W. de Jager, S. Gilad, D.J. Hamilton, J.-O. Hansen, D.W. Higinbotham, J. Juang, X. Jiang, G. Jin, W. Korsch, J.J. LeRose, R.A. Lindgren, N. Liyanage, E. Long, R. Michaels, B. Moffit, P. Monaghan, V. Nelyubin, B.E. Norum, E. Piasetzky, X. Qian, Y. Qiang, S. Riordan, G. Ron, G. Rosner, B. Sawatzky, M. Shabestari, A. Shahinyan, R. Shneor, S. Sirca, R. Subedi, V. Sulkosky, J.W. Watson, B. Wojtsekhowski, Y.-W. Zhang

    2012-09-01

    The techniques for optical calibration of Jefferson Lab's large-acceptance magnetic hadron spectrometer, BigBite, have been examined. The most consistent and stable results were obtained by using a method based on singular value decomposition. In spite of the complexity of the optics, the particles positions and momenta at the target have been precisely reconstructed from the coordinates measured in the detectors by means of a single back-tracing matrix. The technique is applicable to any similar magnetic spectrometer and any particle type. For 0.55 GeV/c protons, we have established the vertex resolution of 1.2 cm, angular resolutions of 7 mrad and 16 mrad (in-plane and out-of-plane, respectively), and a relative momentum resolution of 1.6%.

  5. Calibration of the RPC charge readout in the ARGO-YBJ experiment with the iso-gradient method

    International Nuclear Information System (INIS)

    The ARGO-YBJ experiment is a full coverage array of Resistive Plate Chambers (RPCs) with an active area of 5800 m2. In order to eliminate the response difference of the charge readout from the RPCs, a calibration procedure is carried out with the iso-gradient method. This method also allows the extension of the absolute calibration with the muon telescope including scintillation detectors to all the RPCs in the array. The overall systematic uncertainty in measurements of the number of particles by the RPCs is 10.7%. In general, the method gives results consistent with those from a totally different approach also used in the experiment

  6. Instrumentation and calibration methods for the multichannel measurement of phase and amplitude in optical tomography

    International Nuclear Information System (INIS)

    In this article, we describe the multichannel implementation of an intensity modulated optical tomography system developed at Helsinki University of Technology. The system has two time-multiplexed wavelengths, 16 time-multiplexed source fibers and 16 parallel detection channels. The gain of the photomultiplier tubes (PMTs) is individually adjusted during the measurement sequence to increase the dynamic range of the system by 104. The PMT used has a high quantum efficiency in the near infrared (8% at 800 nm), a fast settling time, and low hysteresis. The gain of the PMT is set so that the dc anode current is below 80 nA, which allows the measurement of phase independently of the intensity. The system allows measurements of amplitude at detected intensities down to 1 fW, which is sufficient for transmittance measurements of the female breast, the forearm, and the brain of early pre-term infants. The mean repeatability of phase and the logarithm of amplitude (ln A) at 100 MHz were found to be 0.08 deg. and 0.004, respectively, in a measurement of a 7 cm phantom with an imaging time of 5 s per source and source optical power of 8 mW. We describe a three-step method of calibrating the phase and amplitude measurements so that the absolute absorption and scatter in tissue may be measured. A phantom with two small cylindrical targets and a second phantom with three rods are measured and reconstructions made from the calibrated data are shown and compared with reconstructions from simulated data

  7. Evaluation and calibration of functional network modeling methods based on known anatomical connections.

    Science.gov (United States)

    Dawson, Debra Ann; Cha, Kuwook; Lewis, Lindsay B; Mendola, Janine D; Shmuel, Amir

    2013-02-15

    -sensitivities, achieving 59-76% for 17min sessions. With a short resting-state fMRI scan of 8.5min, none of the methods predicted the real network well, with Corr (65%) performing best. With increased complexity of the network from 9 to 36 nodes, multivariate methods including PCorr and BayesNet saw a decrease in performance. Artifact-free regression of the global effect increased the c-sensitivity of the top-performing methods. In an overall evaluation across all tests we performed, correlation methods (Corr, ICOV, and PCorr), Patel's Kappa, and BayesNet method PC set themselves somewhat above all other methods. We propose that data-based calibration based on known anatomical connections be integrated into future network studies, in order to maximize sensitivity and reduce false positives.

  8. Global Calibration Method of a Camera Using the Constraint of Line Features and 3D World Points

    Science.gov (United States)

    Xu, Guan; Zhang, Xinyuan; Li, Xiaotao; Su, Jian; Hao, Zhaobing

    2016-08-01

    We present a reliable calibration method using the constraint of 2D projective lines and 3D world points to elaborate the accuracy of the camera calibration. Based on the relationship between the 3D points and the projective plane, the constraint equations of the transformation matrix are generated from the 3D points and 2D projective lines. The transformation matrix is solved by the singular value decomposition. The proposed method is compared with the point-based calibration to verify the measurement validity. The mean values of the root-mean-square errors using the proposed method are 7.69×10-4, 6.98×10-4, 2.29×10-4, and 1.09×10-3 while the ones of the original method are 8.10×10-4, 1.29×10-2, 2.58×10-2, and 8.12×10-3. Moreover, the average logarithmic errors of the calibration method are evaluated and compared with the former method in different Gaussian noises and projective lines. The variances of the average errors using the proposed method are 1.70×10-5, 1.39×10-4, 1.13×10-4, and 4.06×10-4, which indicates the stability and accuracy of the method.

  9. A new method for calibrating a boron isotope paleo-pH proxy using massive Porites corals

    Science.gov (United States)

    Kubota, Kaoru; Yokoyama, Yusuke; Ishikawa, Tsuyoshi; Suzuki, Atsushi

    2015-09-01

    The boron isotope ratio (δ11B) of marine biogenic carbonates can reconstruct pH and pCO2 of seawater, and potentially CO2 concentration in the atmosphere. To date, δ11B-pHSW calibration has been proposed via culturing experiments, where calcifying organisms are cultured under artificially acidified seawater. However, in scleractinian corals, reconstructed pH values using culture-based calibrations do not agree well with actual observations of seawater CO2 chemistry. Thus, another approach is needed to establish a more reliable calibration method. In this study, we established field-based calibrations for Chichijima and Tahiti, both located in subtropical gyres where surface seawater is close to CO2 equilibrium. We suggest a new approach to calibration of δ11B-pH in which the long-term δ11B variation of massive Porites corals is compared with the decreasing pH trend (i.e., ocean acidification) that has occurred since the Industrial Revolution. This calibration will offer a new avenue for studying seawater CO2 chemistry using coral δ11B in diverse settings, such as upwelling regions, coral reefs, and coastal areas.

  10. A novel INS and Doppler sensors calibration method for long range underwater vehicle navigation.

    Science.gov (United States)

    Tang, Kanghua; Wang, Jinling; Li, Wanli; Wu, Wenqi

    2013-10-28

    Since the drifts of Inertial Navigation System (INS) solutions are inevitable and also grow over time, a Doppler Velocity Log (DVL) is used to aid the INS to restrain its error growth. Therefore, INS/DVL integration is a common approach for Autonomous Underwater Vehicle (AUV) navigation. The parameters including the scale factor of DVL and misalignments between INS and DVL are key factors which limit the accuracy of the INS/DVL integration. In this paper, a novel parameter calibration method is proposed. An iterative implementation of the method is designed to reduce the error caused by INS initial alignment. Furthermore, a simplified INS/DVL integration scheme is employed. The proposed method is evaluated with both river trial and sea trial data sets. Using 0.03°/h(1σ) ring laser gyroscopes, 5 × 10-5 g(1σ) quartz accelerometers and DVL with accuracy 0.5% V ± 0.5 cm/s, INS/DVL integrated navigation can reach an accuracy of about 1‰ of distance travelled (CEP) in a river trial and 2‰ of distance travelled (CEP) in a sea trial.

  11. A Novel INS and Doppler Sensors Calibration Method for Long Range Underwater Vehicle Navigation

    Directory of Open Access Journals (Sweden)

    Wenqi Wu

    2013-10-01

    Full Text Available Since the drifts of Inertial Navigation System (INS solutions are inevitable and also grow over time, a Doppler Velocity Log (DVL is used to aid the INS to restrain its error growth. Therefore, INS/DVL integration is a common approach for Autonomous Underwater Vehicle (AUV navigation. The parameters including the scale factor of DVL and misalignments between INS and DVL are key factors which limit the accuracy of the INS/DVL integration. In this paper, a novel parameter calibration method is proposed. An iterative implementation of the method is designed to reduce the error caused by INS initial alignment. Furthermore, a simplified INS/DVL integration scheme is employed. The proposed method is evaluated with both river trial and sea trial data sets. Using 0.03°/h(1σ ring laser gyroscopes, 5 × 10−5 g(1σ quartz accelerometers and DVL with accuracy 0.5% V ± 0.5 cm/s, INS/DVL integrated navigation can reach an accuracy of about 1‰ of distance travelled (CEP in a river trial and 2‰ of distance travelled (CEP in a sea trial.

  12. Calibration of scattering and absorption properties of a liquid diffusive medium at NIR wavelengths. CW method.

    Science.gov (United States)

    Martelli, Fabrizio; Zaccanti, Giovanni

    2007-01-22

    In spite of many progresses achieved both with theories and with experiments in studying light propagation through diffusive media, a reliable method for accurate measurements of the optical properties of diffusive media at NIR wavelengths is, in our opinion, still missing. It is therefore difficult to create a diffusive medium with well known optical properties to be used as a reference. In this paper we describe a method to calibrate the reduced scattering coefficient, mu'(s) , of a liquid diffusive medium and the absorption coefficient, mu(a), of an absorbing medium with a standard error smaller than 2% both on mu'(s) and on mu(a). The method is based on multidistance measurements of fluence into an infinite medium illuminated by a CW source. The optical properties are retrieved with simple inversion procedures (linear fits) exploiting the knowledge of the absorption coefficient of the liquid into which the diffuser and the absorber are dispersed. In this study Intralipid diluted in water has been used as diffusive medium and Indian ink as absorber. For a full characterization of these media measurements of collimated transmittance have also been carried out, from which the asymmetry factor of the scattering function of Intralipid and the single scattering albedo of Indian ink have been determined. PMID:19532267

  13. Methods of Control-Rod Calibration in the Windscale Advanced Gas-Cooled Reactor

    International Nuclear Information System (INIS)

    Different techniques were used to calibrate control rods and to measure individual rod worths during the commissioning of the WAGR. These methods are described and the results are presented. The methods described are: (a ) Air poisoning - Changes in air pressure allow axial movement of rods at the critical condition. Thus rod movement can be related to pressure variation which is equivalent to a reactivity change. Also, rod slope measurements can be made for different rod insertions. (b) Rod slopes - The rods are withdrawn to make the reactor supercritical; then later they are inserted to make the reactor subcritical. From a measurement of the doubling and halving times the change in reactivity between the super- and subcritical states can be determined.- (c ) Absorber addition and withdrawal - The number of fixed localized absorbers is varied to give a method similar to the use of uniform air poisoning. (d) Pulsatron - This technique is used to give subcritical measurements of rod worth. (e) Rod run-in - The reactor is initially critical, and then the rods are run into the core. Analysis of the flux response relates reactivity to rod movement. (author)

  14. Towards monolithic scintillator based TOF-PET systems: practical methods for detector calibration and operation

    Science.gov (United States)

    Borghi, Giacomo; Tabacchini, Valerio; Schaart, Dennis R.

    2016-07-01

    Gamma-ray detectors based on thick monolithic scintillator crystals can achieve spatial resolutions  NN) classification method for x,y-position estimation is accelerated with an algorithm that quickly preselects only the most useful reference events, reducing the computation time for position estimation by a factor of ~200 compared to the previously published k-NN 1D method. Also, the procedures for estimating the DOI and time of interaction are revised to enable full detector calibration by means of fan-beam or flood irradiations only. Moreover, a new technique is presented to allow the use of events in which some of the photosensor pixel values and/or timestamps are missing (e.g. due to dead time), so as to further increase system sensitivity. The accelerated methods were tested on a monolithic scintillator detector specifically developed for clinical PET applications, consisting of a 32 mm  ×  32 mm  ×  22 mm LYSO : Ce crystal coupled to a digital photon counter (DPC) array. This resulted in a spatial resolution of 1.7 mm FWHM, an average DOI resolution of 3.7 mm FWHM, and a CRT of 214 ps. Moreover, the possibility of using events missing the information of up to 16 out of 64 photosensor pixels is shown. This results in only a small deterioration of the detector performance.

  15. A novel INS and Doppler sensors calibration method for long range underwater vehicle navigation.

    Science.gov (United States)

    Tang, Kanghua; Wang, Jinling; Li, Wanli; Wu, Wenqi

    2013-01-01

    Since the drifts of Inertial Navigation System (INS) solutions are inevitable and also grow over time, a Doppler Velocity Log (DVL) is used to aid the INS to restrain its error growth. Therefore, INS/DVL integration is a common approach for Autonomous Underwater Vehicle (AUV) navigation. The parameters including the scale factor of DVL and misalignments between INS and DVL are key factors which limit the accuracy of the INS/DVL integration. In this paper, a novel parameter calibration method is proposed. An iterative implementation of the method is designed to reduce the error caused by INS initial alignment. Furthermore, a simplified INS/DVL integration scheme is employed. The proposed method is evaluated with both river trial and sea trial data sets. Using 0.03°/h(1σ) ring laser gyroscopes, 5 × 10-5 g(1σ) quartz accelerometers and DVL with accuracy 0.5% V ± 0.5 cm/s, INS/DVL integrated navigation can reach an accuracy of about 1‰ of distance travelled (CEP) in a river trial and 2‰ of distance travelled (CEP) in a sea trial. PMID:24169542

  16. Uncertainty from Model Calibration: Applying a New Method to Transport Energy Demand Modelling

    NARCIS (Netherlands)

    Ruijven, B.; Van der Sluijs, J.P.; Van Vuuren, D.P.; Janssen, P.; Heuberger, P.S.C.; De Vries, B.

    2009-01-01

    Uncertainties in energy demand modelling originate from both limited understanding of the real-world system and a lack of data for model development, calibration and validation. These uncertainties allow for the development of different models, but also leave room for different calibrations of a sin

  17. Calibration of measurement sensitivities of multiple micro-cantilever dynamic modes in atomic force microscopy using a contact detection method

    International Nuclear Information System (INIS)

    An accurate experimental method is proposed for on-spot calibration of the measurement sensitivities of multiple micro-cantilever dynamic modes in atomic force microscopy. One of the key techniques devised for this method is a reliable contact detection mechanism that detects the tip-surface contact instantly. At the contact instant, the oscillation amplitude of the tip deflection, converted to that of the deflection signal in laser reading through the measurement sensitivity, exactly equals to the distance between the sample surface and the cantilever base position. Therefore, the proposed method utilizes the recorded oscillation amplitude of the deflection signal and the base position of the cantilever at the contact instant for the measurement sensitivity calibration. Experimental apparatus along with various signal processing and control modules was realized to enable automatic and rapid acquisition of multiple sets of data, with which the calibration of a single dynamic mode could be completed in less than 1 s to suppress the effect of thermal drift and measurement noise. Calibration of the measurement sensitivities of the first and second dynamic modes of three micro-cantilevers having distinct geometries was successfully demonstrated. The dependence of the measurement sensitivity on laser spot location was also experimentally investigated. Finally, an experiment was performed to validate the calibrated measurement sensitivity of the second dynamic mode of a micro-cantilever.

  18. A likelihood method to cross-calibrate air-shower detectors

    CERN Document Server

    Dembinski, H P; Mariş, I C; Roth, M; Veberič, D

    2016-01-01

    We present a detailed statistical treatment of the energy calibration of hybrid air-shower detectors, which combine a surface detector array and a fluorescence detector, to obtain an unbiased estimate of the calibration curve. The special features of calibration data from air showers prevent unbiased results, if a standard least-squares fit is applied to the problem. We develop a general maximum-likelihood approach, based on the detailed statistical model, to solve the problem. Our approach was developed for the Pierre Auger Observatory, but the applied principles are general and can be transferred to other air-shower experiments, even to the cross-calibration of other observables. Since our general likelihood function is expensive to compute, we derive two approximations with significantly smaller computational cost. In the recent years both have been used to calibrate data of the Pierre Auger Observatory. We demonstrate that these approximations introduce negligible bias when they are applied to simulated t...

  19. An innovative method for 192Ir HDR calibration by farmer chamber, V-film, and solid phantom

    International Nuclear Information System (INIS)

    A simple, practical and economical technique was proposed to calibrate an 192Ir HDR brachytherapy source in terms of air kerma strength. This technique makes use of the 0.6 cm3 Farmer type ion chamber, radiographic film and polystyrene phantom. These tools are commonly used for dosimetry quality assurance of the clinical linear accelerator. In this study, the Exradin A19, PTW N30004 and TM30001 Farmer type ion chambers were used for the calibration of the 192Ir HDR source. To perform the calibration, a 25.4x30.5 cm2 radiographic film was taped on a piece of polystyrene plate, and a straight applicator probe of a HDR brachytherapy unit and the Farmer type ion chamber were affixed to the film envelope. The film was irradiated by the 192Ir source, followed by an exposure in the simulator X-ray beam. The film set with the film removed was then placed on a 5 cm thick polystyrene phantom for calibration measurement. Based on the electrometer reading from the Farmer type ion chamber irradiated by 192Ir and the measured source-to-chamber distance by means of the images on the developed film, we can calculate the air kerma strength of the 192Ir using the new technique. Our calibration results were compared to the data provided by the manufacturer and that of five different well type ion chambers, namely, Sun Nuclear cooperation (SNC) 1008, Nucletron SDS 077.091, SDS 077.094, PTW TN33004 and Standard Imaging (SI) HDR-1000 Plus. The differences were all within 1.6%. Relative to the '7-distance measurement technique' by Stump et al., 2002, our method is more efficient if our empirical formula was used. In summary, our method is simpler and cost-effective to calibrate an 192Ir HDR brachytherapy source for those hospitals without a calibration jig or a well type ion chamber.

  20. a Novel Approach to Camera Calibration Method for Smart Phones Under Road Environment

    Science.gov (United States)

    Lee, Bijun; Zhou, Jian; Ye, Maosheng; Guo, Yuan

    2016-06-01

    Monocular vision-based lane departure warning system has been increasingly used in advanced driver assistance systems (ADAS). By the use of the lane mark detection and identification, we proposed an automatic and efficient camera calibration method for smart phones. At first, we can detect the lane marker feature in a perspective space and calculate edges of lane markers in image sequences. Second, because of the width of lane marker and road lane is fixed under the standard structural road environment, we can automatically build a transformation matrix between perspective space and 3D space and get a local map in vehicle coordinate system. In order to verify the validity of this method, we installed a smart phone in the `Tuzhi' self-driving car of Wuhan University and recorded more than 100km image data on the road in Wuhan. According to the result, we can calculate the positions of lane markers which are accurate enough for the self-driving car to run smoothly on the road.

  1. Application of an Artificial Intelligence Method for Velocity Calibration and Events Location in Microseismic Monitoring

    Science.gov (United States)

    Yang, Y.; Chen, X.

    2013-12-01

    Good quality hydraulic fracture maps are heavily dependent upon the best possible velocity structure. Particle Swarm Optimization inversion scheme, an artificial intelligence technique for velocity calibration and events location could serve as a viable option, able to produce high quality data. Using perforation data to recalibrate the 1D isotropic velocity model derived from dipole sonic logs (or even without them), we are able to get the initial velocity model used for consequential events location. Velocity parameters can be inverted, as well as the thickness of the layer, through an iterative procedure. Performing inversion without integrating available data is unlikely to produce reliable results; especially if there are only one perforation shot and a single poor-layer-covered array along with low signal/noise ratio signal. The inversion method was validated via simulations and compared to the Fast Simulated Annealing approach and the Conjugate Gradient method. Further velocity model refinement can be accomplished while calculating events location during the iterative procedure minimizing the residuals from both sides. This artificial intelligence technique also displays promising application to the joint inversion of large-scale seismic activities data.

  2. Heat-capacity measurements on small samples: The hybrid method

    NARCIS (Netherlands)

    J.C.P. Klaasse; E.H. Brück

    2008-01-01

    A newly developed method is presented for measuring heat capacities on small samples, particularly where thermal isolation is not sufficient for the use of the traditional semiadiabatic heat-pulse technique. This "hybrid technique" is a modification of this heat-pulse method in case the temperature

  3. The Role of Mathematical Methods in Efficiency Calibration and Uncertainty Estimation in Gamma Based Non-Destructive Assay - 12311

    International Nuclear Information System (INIS)

    Mathematical methods are being increasingly employed in the efficiency calibration of gamma based systems for non-destructive assay (NDA) of radioactive waste and for the estimation of the Total Measurement Uncertainty (TMU). Recently, ASTM (American Society for Testing and Materials) released a standard guide for use of modeling passive gamma measurements. This is a testimony to the common use and increasing acceptance of mathematical techniques in the calibration and characterization of NDA systems. Mathematical methods offer flexibility and cost savings in terms of rapidly incorporating calibrations for multiple container types, geometries, and matrix types in a new waste assay system or a system that may already be operational. Mathematical methods are also useful in modeling heterogeneous matrices and non-uniform activity distributions. In compliance with good practice, if a computational method is used in waste assay (or in any other radiological application), it must be validated or benchmarked using representative measurements. In this paper, applications involving mathematical methods in gamma based NDA systems are discussed with several examples. The application examples are from NDA systems that were recently calibrated and performance tested. Measurement based verification results are presented. Mathematical methods play an important role in the efficiency calibration of gamma based NDA systems. This is especially true when the measurement program involves a wide variety of complex item geometries and matrix combinations for which the development of physical standards may be impractical. Mathematical methods offer a cost effective means to perform TMU campaigns. Good practice demands that all mathematical estimates be benchmarked and validated using representative sets of measurements. (authors)

  4. Calibration of X-Ray diffractometer by the experimental comparison method

    Energy Technology Data Exchange (ETDEWEB)

    Dudka, A. P., E-mail: dudka@ns.crys.ras.ru [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation)

    2015-07-15

    A software for calibrating an X-ray diffractometer with area detector has been developed. It is proposed to search for detector and goniometer calibration models whose parameters are reproduced in a series of measurements on a reference crystal. Reference (standard) crystals are prepared during the investigation; they should provide the agreement of structural models in repeated analyses. The technique developed has been used to calibrate Xcalibur Sapphire and Eos, Gemini Ruby (Agilent) and Apex x8 and Apex Duo (Bruker) diffractometers. The main conclusions are as follows: the calibration maps are stable for several years and can be used to improve structural results, verified CCD detectors exhibit significant inhomogeneity of the efficiency (response) function, and a Bruker goniometer introduces smaller distortions than an Agilent goniometer.

  5. A method for the calibration of concave 90Sr+90Y ophthalmic applicators

    International Nuclear Information System (INIS)

    At the Amersham Laboratory (Amersham, UK) absorbed-dose rate in tissue at a depth of 7 mg cm-2 from curved ophthalmic applicators is measured with calibrated scintillator probes (Amersham International 1979, Sinclair and Trott 1956). The probes are approximately 3 mm in diameter, 0.5 mm thick and are covered with 7 mg cm-2 of aluminium. They are calibrated using standard sources whose dose rate has been determined using an extrapolation chamber equipped with a 3 mm diameter collecting electrode. Crucial to this technique is the availability of well calibrated sources of nearly the same geometry and dose rate as the source to be calibrated. A technique is presented here which yields accurate measurement of the surface absorbed-dose rate in a very simple and straightforward fashion. (author)

  6. PLEIADES-HR 1A&1B image quality commissioning: innovative radiometric calibration methods and results

    Science.gov (United States)

    Martin, Vincent; Blanchet, Gwendoline; Kubik, Philippe; Lacherade, Sophie; Latry, Christophe; Lebegue, Laurent; Lenoir, Florie; Porez-Nadal, Florence

    2013-09-01

    PLEIADES is an earth observing system conducted by the French National Space Agency, CNES. It consists of two satellites launched on December 2011 (PHR-1A) and December 2012 (PHR-1B), both designed to provide optical pushbroom imagery on five spectral bands to civilian and defense users, with ground sample distance up to 70 cm. During inflight image quality commissioning, radiometric activities included inter-detector normalization coefficients computation, refocusing operations, MTF assessment and estimation of signal to noise ratios. This paper presents inflight results for both satellites. It focuses on several innovative methods that were implemented, taking advantage of the satellite platform great agility. These methods are based on processing images obtained through dedicated exotic guidance. In particular, slow-motion steering enables an efficient estimation of the instrumental noise model, since during acquisition each detector has been viewing a stable ground target along different time samples. Conversely, rotated retina guidance is used to guarantee that all different elementary detectors have successively viewed the same set of landscape samples during acquisition. Non-uniformity of detector sensitivities can then be characterized, and on-board coefficients used prior to compression can be calibrated in order to prevent vertical striping effects on operational images. Defocus control and Point Spread Function estimation can be easily obtained through processing acquisitions of stars associated to various spectral characteristics, for different adjustments of the refocusing system. All these methods allow an accurate estimation of radiometric performance on the whole range of specified spectral radiances, while drastically reducing the number of required acquisitions on natural targets.

  7. A novel method for the in situ calibration of flow effects on a phosphate passive sampler.

    Science.gov (United States)

    Sara O'Brien, Dominique; Chiswell, Barry; Mueller, Jochen F

    2009-01-01

    Monitoring of nutrients including phosphate in the aquatic environment remains a challenge. In the last decade passive sampling techniques have been developed that facilitates the time integrated monitoring of phosphate (P) through the use of an iron hydroxide (ferrihydrite) to sequester dissolved phosphate from solution. These methods rely on established techniques to negate the effects of flow (and associated turbulence) and control the rate at which chemicals accumulate within passive samplers. In this study we present a phosphate sampler within which a suspension of ferrihydrite is contained behind a commercially available membrane. Accumulation of dissolved phosphates into the P-sampler is governed by the rate at which ions are diffusing through the membrane and the water boundary layer (WBL). As the WBL changes subject to flow we have adopted an in situ calibration technique based on the dissolution of gypsum to predict the change in the rate of uptake dependent on flow. Here we demonstrate that the loss of gypsum from the passive flow monitor (PFM) can be used to predict the sampling rate (the volume of water extracted per day) for phosphate as a function of water velocity. The outcome of this study presents a new in-field tool for more accurate prediction of the effect of flow/turbulence on the uptake kinetics into passive samplers that is controlled by the diffusion of the chemical of interest through the stagnant water boundary layer. PMID:19137160

  8. Radioactivity in environmental samples: calibration standards measurement methods, quality assurance, and data analysis

    International Nuclear Information System (INIS)

    The numerous environmental radioactivity measurements made by and for the U.S. Environmental Protection Agency (U.S.EPA) include measurements on samples of water, urine, food, milk, and air filters. Calibration standards are listed which are available in the form of water solutions and soils for a wide range of radionuclides. Method validation procedures for U.S. EPA approval include protocol development and single-laboratory and multiple-laboratory evaluation for precision and accuracy. Inter-laboratory comparison studies are conducted for both cross-check and performance evaluation samples and involve 295 federal, state, and local laboratories. For water samples, 80% to 90% of the participating laboratories are within the control limits for most of the radionuclides measured; however, some problem areas exist, especially for radium-228 and strontium-89 and -90. For milk and food samples, more than 90% of the laboratories are within control limits for cobalt-60 and cesium-137 but some problems exist for the measurement of strontium-90, iodine-131, and potassium-40. For tritium, 91% of the laboratories are within the control limit for water samples and 87% are within the control limits for the urine samples. The laboratory performance for air filter samples shows some problems for gross beta, strontium-90 and cesium-137 measurements. (author)

  9. Calibration of KE C Value in Acidic Red Soils with Fumigation-Extraction Method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Commonly used KEC value (0.45) of the fumigation-extraction (FE) method was obtained on the basis of temperate neutral soils. To ascertain its applicability to acidic red soils widespread in southern China and other subtropical regions, the KEC value was investigated based on 8 acidic red soils by in situ labelling of native soil microorganisms using 14C-labelled glucose. Realistic KEC value for red soils could be obtained by in situ 14C-labelling as long as an incubation period of 72 h is adopted after addition of 14C glucose to soil. The single KEC values for the eight red soils ranged from 0.27 to 0.35 and averaged 0.31. Lower KEC value obtained in red soils probably resulted from different soil quality, compared with other types of soil,which causes possible changes in microbial community structure and extractability of cellular component.Microbial biomass C contents of the eight red soils measured using a unique and constant KEC value of 0.45 decreased by 22.2%~40% in comparison to those using variable KEC values. The results suggest that microbial biomass C would be significantly underestimated using the present KEC value and a calibration of the KEC value is necessary for red soils.``

  10. Research on autofocusing method with automatic calibration for aerial camera based on imaging resolution

    Science.gov (United States)

    Zhao, Yu-liang; Zhao, Hong-qiang; Li, Shu-jun; Zhang, Yu-ye

    2014-09-01

    Air materiel depot is a warehouse which store consumed all the parts and equipment vault of the plane. In order to ensure the various aviation equipment integrity of the backup piece rate, the inside temperature of depot must be controlled within a certain range. Therefore, the depot must be equipped a self-contained temperature real-time monitoring system. This paper presents a distributed temperature sensing alarm system to apply to real-time measure spatial distribution of temperature field. In order to eliminate influence to the scattering strength from the light source instability and the fiber bending splice loss and to improve temperature measurement accuracy, the system design used dual-channel dual-wavelength comparison method which make Anti-Stokes as signal channel and Stokes as a reference channel to collect signals of two channel respectively and detect the ratio of the two channels' signals. The light of LD directional coupling to the sensing optical fiber in the temperature field to test, domain reflect light from the sensing optical fiber directional coupling to receive channel again, Rayleigh domain reflect light is filtered after optical filter, the Anti-Stokes and Stokes are both taken out, converted and magnified, the two signals is digitalized by A/D Converter, and written to the storage machine , which linear cumulative to the content of the storage unit, The distributed measurement of the temperature field to test is finished. The collected 2900 measuring points real-time on 2km of optical fiber. The spatial resolution of the system was 0.7m, measurement range was -20-370 °C, and measurement error was +/- 2 °C. All index of the system achieved the desired objective. To get an accurate temperature field spatial distribution and the information of temporal variation, the system enabled real-time temperature of aviation depot monitoring and early warning. As a new sensing technology, the distributed fiber optic sensor has the functions of self

  11. In-flight calibration of satellite ion composition data using artificial intelligence methods

    International Nuclear Information System (INIS)

    The scope of this report is to evaluate some of the cognitive analyzing techniques that are available and that might be useful for calibration, validation and data analysis of a satellite measurement system. As an example, these cognitive techniques are used to perform a post launch calibration of the three-dimensional ion composition, TICS, on the Freja satellite. 17 refs, 28 figs, 6 tabs

  12. A Method Suitable for In-Flight Calibration of a UAV Hyperspectral Remote Sensor

    OpenAIRE

    Li, Haiwei; Zhang, Hao; Chen, Zhengchao

    2014-01-01

    Imagery acquired with unmanned aerial vehicles (UAVs) has a great potential for incorporation into natural resource monitoring protocols due to their ability to be deployed quickly and repeatedly. A valid radiometric calibration of radiance measuring instruments is required for physically based analysis of the measured data. In the autumn of 2013, an Unmanned Aerial Vehicle hyperspectral calibration experiment of the HeadWall imaging spectrometer was conducted at a civilian airport in Suizhon...

  13. A Monte Carlo (MC) based individual calibration method for in vivo x-ray fluorescence analysis (XRF)

    Science.gov (United States)

    Hansson, Marie; Isaksson, Mats

    2007-04-01

    X-ray fluorescence analysis (XRF) is a non-invasive method that can be used for in vivo determination of thyroid iodine content. System calibrations with phantoms resembling the neck may give misleading results in the cases when the measurement situation largely differs from the calibration situation. In such cases, Monte Carlo (MC) simulations offer a possibility of improving the calibration by better accounting for individual features of the measured subjects. This study investigates the prospects of implementing MC simulations in a calibration procedure applicable to in vivo XRF measurements. Simulations were performed with Penelope 2005 to examine a procedure where a parameter, independent of the iodine concentration, was used to get an estimate of the expected detector signal if the thyroid had been measured outside the neck. An attempt to increase the simulation speed and reduce the variance by exclusion of electrons and by implementation of interaction forcing was conducted. Special attention was given to the geometry features: analysed volume, source-sample-detector distances, thyroid lobe size and position in the neck. Implementation of interaction forcing and exclusion of electrons had no obvious adverse effect on the quotients while the simulation time involved in an individual calibration was low enough to be clinically feasible.

  14. The use of suitable pseudo-invariant targets for MIVIS data calibration by the empirical line method

    Science.gov (United States)

    Mei, Alessandro; Bassani, Cristiana; Fontinovo, Giuliano; Salvatori, Rosamaria; Allegrini, Alessia

    2016-04-01

    The Empirical Line Method (ELM) enables the calibration of multi- and hyper-airborne/satellite image converting DN or radiance to reflectance values performed by using at ground data. High quality outcome can be reached with the selection of appropriate Pseudo-Invariant Targets (PIT). In this paper, spectral variability of "usual" (asphalt and concrete) and "unusual" (calcareous gravel, basaltic paving, concrete bricks, tartan paving and artificial turf) PITs is retrieved for ELM application. Such PITs are used to calibrate the Multispectral Infrared and Visible Imaging Spectrometer (MIVIS) airborne sensor in 12 different Runs. Firstly, processing of field spectral data enables the evaluation of pseudo-invariance of targets by studying their spectral changes in space and in time. Finally, these surfaces are used as Ground Calibration (GCT) and Validation Targets (GVT) in ELM. High calibration accuracy values are observed in Visible (VIS) range (98.9%) while a general decrease of accuracy in Near-InfraRed (NIR) (96.6%) and Middle-InfraRed (SWIR) (88.1%) are reached. Outcomes show that "usual" surfaces as asphalt and concrete and "unusual" surfaces such as tartan can be successfully used for MIVIS image calibration.

  15. Primary calibration of solar cells based on DSR method at the National Institute of Metrology of China

    Science.gov (United States)

    He, Yingwei; Xiong, Limin; Zhang, Junchao; Meng, Haifeng; Cai, Chuan; Zhang, Bifeng; Xie, Linlin; Liu, Dingpu

    2015-08-01

    A primary standard measurement facility based on differential spectral responsivity (DSR) method for calibration of reference solar cells was realized at National Institute of Metrology (NIM), China. The primary calibration of the critical spectral parameters and short-circuit current of reference cells, not only with WPVS (World photovoltaic Scale) design but with non-regularly shaped, can be performed by this standard facility. The linearity measurement can be carried out by measuring DSR of the solar cells at different bias levels in the spectral range from 300nm to 1200nm. The characterization and performance of the facility were reported. An uncertainty of 0.9% (k=2) for short-circuit current of WPVS reference solar cells was able to be obtained. A more accurate and better calibration service for solar photovoltaic (PV) cells could be provided to local or international solar cell research community, testing labs and industry users and manufacturers.

  16. A novel method for calibration and monitoring of time synchronization of TOF-PET scanners by means of cosmic rays

    CERN Document Server

    Silarski, M; Bednarski, T; Moskal, P; Białas, P; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowal, J; Kowalski, P; Kozik, T; Krzemień, W; Molenda, M; Niedźwiecki, Sz; Pałka, M; Pawlik, M; Raczyński, L; Rudy, Z; Salabura, P; Sharma, N G; Słomski, A; Smyrski, J; Strzelecki, A; Wiślicki, W; Zieliński, M; Zoń, N

    2013-01-01

    All of the present methods for calibration and monitoring of TOF-PET scanner detectors utilize radioactive isotopes such as e.g. $^{22}$Na or $^{68}$Ge, which are placed or rotate inside the scanner. In this article we describe a novel method based on the cosmic rays application to the PET calibration and monitoring methods. The concept allows to overcome many of the drawbacks of the present methods and it is well suited for newly developed TOF-PET scanners with a large longitudinal field of view. The method enables also monitoring of the quality of the scintillator materials and in general allows for the continuous quality assurance of the PET detector performance.

  17. A Bayesian method for calculating real-time quantitative PCR calibration curves using absolute plasmid DNA standards

    Directory of Open Access Journals (Sweden)

    Haugland Richard A

    2008-02-01

    Full Text Available Abstract Background In real-time quantitative PCR studies using absolute plasmid DNA standards, a calibration curve is developed to estimate an unknown DNA concentration. However, potential differences in the amplification performance of plasmid DNA compared to genomic DNA standards are often ignored in calibration calculations and in some cases impossible to characterize. A flexible statistical method that can account for uncertainty between plasmid and genomic DNA targets, replicate testing, and experiment-to-experiment variability is needed to estimate calibration curve parameters such as intercept and slope. Here we report the use of a Bayesian approach to generate calibration curves for the enumeration of target DNA from genomic DNA samples using absolute plasmid DNA standards. Results Instead of the two traditional methods (classical and inverse, a Monte Carlo Markov Chain (MCMC estimation was used to generate single, master, and modified calibration curves. The mean and the percentiles of the posterior distribution were used as point and interval estimates of unknown parameters such as intercepts, slopes and DNA concentrations. The software WinBUGS was used to perform all simulations and to generate the posterior distributions of all the unknown parameters of interest. Conclusion The Bayesian approach defined in this study allowed for the estimation of DNA concentrations from environmental samples using absolute standard curves generated by real-time qPCR. The approach accounted for uncertainty from multiple sources such as experiment-to-experiment variation, variability between replicate measurements, as well as uncertainty introduced when employing calibration curves generated from absolute plasmid DNA standards.

  18. A comparison of methods for calibration and use of multi-component strain gauge wind tunnel balances

    Science.gov (United States)

    Galway, R. D.

    1980-03-01

    A method is presented for calibration of strain-gauge balances which does not require that the components can be loaded independently. Applicable to both 'internal' and 'external' types of balance, the procedure uses a single varying calibration load to determine all linear and non-linear calibration coefficients. Constant 'secondary' loads on one or more components are unnecessary, although they may be used if desired. The usual iterative solution of the second order balance equations is outlined, and an approximate non-iterative scheme is included for completeness, though not recommended. Two methods of accounting for dependency of the calibration coefficients on the signs of the component loads are presented. A concept of 'buoyancy' is introduced to simplify the application of force balance tares, and a procedure for determining the component outputs for absolute zero load (the 'buoyant' offsets) is given. Balance data at a series of model attitudes are used to define these offsets, and also the coefficients in the equations defining the component load distribution of the tare weight at any attitude. The topics covered are ideally suited to formulation and solution by matrix methods, which have been used throughout.

  19. Establishment of a new calibration method of pencil ionization chamber for dosimetry in computed tomography

    International Nuclear Information System (INIS)

    Pencil ionization chambers are used for beam dosimetry in computed tomography equipment (CT). In this study, a new calibration methodology was established, in order to make the Calibration Laboratory of Instituto de Pesquisas Energeticas e Nucleares (LCI) suitable to international metrological standards, dealing with specific procedures for calibration of these chambers used in CT. Firstly, the setup for the new RQT radiation qualities was mounted, in agreement with IEC61267 from the International Electrotechnical Commission (IEC). After the establishment of these radiation qualities, a specific calibration methodology for pencil ionization chambers was set, according to Technical Report Series No. 457, from the International Atomic Energy Agency (IAEA), which describes particularities of the procedure to be followed by the Secondary Standard Dosimetry Laboratories (SSDL's), concerning to collimation and positioning related to the radiation beam. Initially, PPV (kV) measurements and the determination of copper additional filtrations were carried out, measuring the half value layers (HVL) recommended by the IEC 61267 standard, after that the RQT 8, RQT 9 and RQT 10 radiation quality references were established. For additional filters, aluminum and copper of high purity (around 99.9%) were used. RQT's in thickness of copper filters equivalent to the set 'RQR (Al) + Additional Filtration (Cu)' was directly found by an alternative methodology used to determine additional filtrations, which is a good option when RQR's have not the possibility of be setting up. With the establishment of this new methodology for the ionization pencil chambers calibration, the LCI is ready to calibrate these instruments according to the most recent international standards. Therefore, an improvement in calibration traceability, as well as in metrological services offered by IPEN to all Brazil is achieved. (author)

  20. An extended numerical calibration method for an electrochemical probe in thin wavy flow with large amplitude waves

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Ki Yong; No, Hee Cheon [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of)

    1998-12-31

    The calibrating method for an electrochemical probe, neglecting the effect of the normal velocity on the mass transport, can cause large errors when applied to the measurement of wall shear rates in thin wavy flow with large amplitude waves. An extended calibrating method is developed to consider the contributions of the normal velocity. The inclusion of the turbulence-induced normal velocity term is found to have a negligible effect on the mass transfer coefficient. The contribution of the wave-induced normal velocity can be classified on the dimensionless parameter, V. If V is above a critical value of V, V{sub crit}, the effects of the wave-induced normal velocity become larger with an increase in V. While its effects negligible for inversely. The present inverse method can predict the unknown shear rate more accurately in thin wavy flow with large amplitude waves than the previous method. 18 refs., 8 figs. (Author)

  1. Joining direct and indirect inverse calibration methods to characterize karst, coastal aquifers

    Science.gov (United States)

    De Filippis, Giovanna; Foglia, Laura; Giudici, Mauro; Mehl, Steffen; Margiotta, Stefano; Negri, Sergio

    2016-04-01

    Parameter estimation is extremely relevant for accurate simulation of groundwater flow. Parameter values for models of large-scale catchments are usually derived from a limited set of field observations, which can rarely be obtained in a straightforward way from field tests or laboratory measurements on samples, due to a number of factors, including measurement errors and inadequate sampling density. Indeed, a wide gap exists between the local scale, at which most of the observations are taken, and the regional or basin scale, at which the planning and management decisions are usually made. For this reason, the use of geologic information and field data is generally made by zoning the parameter fields. However, pure zoning does not perform well in the case of fairly complex aquifers and this is particularly true for karst aquifers. In fact, the support of the hydraulic conductivity measured in the field is normally much smaller than the cell size of the numerical model, so it should be upscaled to a scale consistent with that of the numerical model discretization. Automatic inverse calibration is a valuable procedure to identify model parameter values by conditioning on observed, available data, limiting the subjective evaluations introduced with the trial-and-error technique. Many approaches have been proposed to solve the inverse problem. Generally speaking, inverse methods fall into two groups: direct and indirect methods. Direct methods allow determination of hydraulic conductivities from the groundwater flow equations which relate the conductivity and head fields. Indirect methods, instead, can handle any type of parameters, independently from the mathematical equations that govern the process, and condition parameter values and model construction on measurements of model output quantities, compared with the available observation data, through the minimization of an objective function. Both approaches have pros and cons, depending also on model complexity. For

  2. A self-calibration method for the edge Thomson scattering diagnostic in ITER

    International Nuclear Information System (INIS)

    Calibration of spectral transmissivity of the collection and transmission optics is one of the most crucial issues for the Thomson scattering diagnostic system. Radioactivation of the vacuum vessel in ITER makes it difficult to calibrate spectral transmissivity in areas near the vacuum vessel. By using an additional calibration laser whose wavelength differs from those of the diagnostic laser and equipping two lasers with Thomson scattering lights, we can obtain the electron temperature and the relative transmissivity of each spectral channel of the polychromator from the Thomson scattering signal itself. A ruby laser is a promising candidate as a calibration laser because the wavelength does not diverge greatly from that of a diagnostic laser and from the lower limit of an observable wavelength. Even if the signal-noise ratio degrades, the available electron temperature data during calibration operations remain largely unaffected. A degrading signal-noise ratio increases statistical error in electron temperature data and relative spectral transmissivity. Even when the spectral transmissivity is unknown, electron temperature data may be obtained within a 10% margin of error, which fulfills the requirements for edge electron temperature measurement in ITER. (author)

  3. A likelihood method to cross-calibrate air-shower detectors

    Science.gov (United States)

    Dembinski, Hans Peter; Kégl, Balázs; Mariş, Ioana C.; Roth, Markus; Veberič, Darko

    2016-01-01

    We present a detailed statistical treatment of the energy calibration of hybrid air-shower detectors, which combine a surface detector array and a fluorescence detector, to obtain an unbiased estimate of the calibration curve. The special features of calibration data from air showers prevent unbiased results, if a standard least-squares fit is applied to the problem. We develop a general maximum-likelihood approach, based on the detailed statistical model, to solve the problem. Our approach was developed for the Pierre Auger Observatory, but the applied principles are general and can be transferred to other air-shower experiments, even to the cross-calibration of other observables. Since our general likelihood function is expensive to compute, we derive two approximations with significantly smaller computational cost. In the recent years both have been used to calibrate data of the Pierre Auger Observatory. We demonstrate that these approximations introduce negligible bias when they are applied to simulated toy experiments, which mimic realistic experimental conditions.

  4. Reproducible methods for calibrating the backscattered electron signal for quantitative assessment of mineral content in bone

    Energy Technology Data Exchange (ETDEWEB)

    Boyce, T.M.; Bloebaum, R.D.; Bachus, K.N.; Skedros, J.G. (VA Medical Center, Salt Lake City, UT (USA))

    1990-09-01

    Backscattered electron (BSE) imaging shows promise for orthopaedic and bone research. BSE images of bone may be captured on-line directly from the scanning electron microscope (SEM), and then analyzed to produce a backscattered electron profile (BSEP), a modified image graylevel histogram which is representative of the mineral content in bone. The goals of this work were (1) develop a reproducible graylevel calibration technique for bone specimens, and (2) determine a conservative time interval during which SEM operating conditions would remain stable. Calibration standards containing pure aluminum and pure magnesium wires were placed in the SEM with human cancellous bone. Baseline imaging conditions were first established by adjusting the SEM until the bone image displayed good resolution and graylevel separation between regions of different mineral content. Microscope brightness and contrast controls were randomly changed to initiate the new operating conditions of another imaging session, and graylevel values from the calibration metals were used to readjust the microscope back to baseline operating conditions. Weighted mean graylevel values of the BSEPs from calibration trials were compared to those of the baseline. Data showed that bone images could be reproduced within 1.2 percent. It was also concluded that our equipment required calibration checks at 20 minute intervals.

  5. Calibration of the laser induced pressure pulse method when using a semiconducting electrode as the laser target

    OpenAIRE

    Ma, Peng; Zhang, Yewen; Holé, Stéphane; Zheng, Feihu; An, Zhenlian

    2016-01-01

    Space charge distributions can directly be qualitatively estimated from a laser induced pressure pulse (LIPP) signal. To obtain precise quantitative space charge density, calibration of the LIPP method is necessary which requires an ideal measured signal. However, when a carbon loaded polymer electrode is used as the laser target, a long signal tail can be found. The cause of the signal tail is analyzed in this study and two methods are proposed to correct the experimental signals. According ...

  6. A comparison of calibration methods for quantifictation of Basmati and non-Basmati rice using microsatellite analysis

    OpenAIRE

    Colyer, Alison; Macarthur, Roy; Lloyd, Joy; Hird, Hez

    2008-01-01

    Abstract The accurate quantitation of non-Basmati rice in Basmati rice is central to the successful prosecution of adulteration, where non-basmati rice has been substituted for Basmati rice. The current method and three alternatives of constructing calibration curves for the measurement of non-Basmati rice in Basmati rice using microsatellite analysis were investigated. The methods compared involved power regression, linear regression (with and without log10 transformation) and h...

  7. Calibration method for a in vivo measurement system using mathematical simulation of the radiation source and the detector

    International Nuclear Information System (INIS)

    A Monte Carlo program which uses a voxel phantom has been developed to simulate in vivo measurement systems for calibration purposes. The calibration method presented here employs a mathematical phantom, produced in the form of volume elements (voxels), obtained through Magnetic Resonance Images of the human body. The calibration method uses the Monte Carlo technique to simulate the tissue contamination, the transport of the photons through the tissues and the detection of the radiation. The program simulates the transport and detection of photons between 0.035 and 2 MeV and uses, for the body representation, a voxel phantom with a format of 871 slices each of 277 x 148 picture elements. The Monte Carlo code was applied to the calibration of in vivo systems and to estimate differences in counting efficiencies between homogeneous and non-homogeneous radionuclide distributions in the lung. Calculations show a factor of 20 between deposition of 241 Am at the back compared with the front of the lung. The program was also used to estimate the 137 Cs body burden of an internally contaminated individual, counted with an 8 x 4 Nal (TI) detector and an 241 Am body burden of an internally contaminated individual, who was counted using a planar germanium detector. (author)

  8. New methods for the calibration of colour indices and O4 absorptions obtained from MAX-DOAS measurements

    Science.gov (United States)

    Wagner, Thomas; Beirle, Steffen; Dörner, Steffen; Remmers, Julia; Shaiganfar, Reza; Wang, Yang

    2015-04-01

    So called colour indices (CI) are defined as ratio of radiances at different wavelengths. CI measurements from Multi-AXis-Differential Absorption Spectroscopy (MAX-DOAS) observations are important for the detection and classification of clouds and aerosols. However, usually, MAX-DOAS instruments are not radiometrically calibrated. Thus the measured CI can not be directly compared to results from radiative transfer simulations. This shortcoming prevents the standardisation of cloud classification schemes. In addition to the CI, also the absorption of the oxygen dimer (O4) can be used for cloud detection, in particular for the detection of optically thick clouds or fog. However, also the retrieved O4 absorption has first to be calibrated (the absorption of the Fraunhofer reference spectrum has to be determined) before it can be used in a standardised way. We developed methods for the calibration of the CI and the O4 absorption derived from MAX-DOAS observations. They are based on the comparison of measurements and simulation results for well-defined atmospheric conditions. We estimate the accuracy of our calibration methods to < 10%.

  9. Novel Calibration Method for Switched Capacitor Arrays Enables Time Measurements with Sub- Picosecond Resolution

    CERN Document Server

    Stricker-Shaver, D A; Pichler, B J

    2014-01-01

    Switched capacitor arrays ASICs are becoming more and more popular for the readout of detector signals, since the sampling frequency of typically several gigasamples per second allows excellent pile-up rejection and time measurements. They suffer however from the fact that their sampling bins are not equidistant in time, given by limitations of the chip process. In the past, this limited time measurements of optimal signals to about 5-25 ps in accuracy, depending on the specific chip, even after careful time calibrations. This paper introduces a novel time calibration, which allows pushing this limit below 1 ps, and also determines the true sampling speed. Various test measurements with different boards based on the DRS4 ASIC indicate that the new calibration is valid over a wide temperature range and stable over time.

  10. Linear model correction: A method for transferring a near-infrared multivariate calibration model without standard samples.

    Science.gov (United States)

    Liu, Yan; Cai, Wensheng; Shao, Xueguang

    2016-12-01

    Calibration transfer is essential for practical applications of near infrared (NIR) spectroscopy because the measurements of the spectra may be performed on different instruments and the difference between the instruments must be corrected. For most of calibration transfer methods, standard samples are necessary to construct the transfer model using the spectra of the samples measured on two instruments, named as master and slave instrument, respectively. In this work, a method named as linear model correction (LMC) is proposed for calibration transfer without standard samples. The method is based on the fact that, for the samples with similar physical and chemical properties, the spectra measured on different instruments are linearly correlated. The fact makes the coefficients of the linear models constructed by the spectra measured on different instruments are similar in profile. Therefore, by using the constrained optimization method, the coefficients of the master model can be transferred into that of the slave model with a few spectra measured on slave instrument. Two NIR datasets of corn and plant leaf samples measured with different instruments are used to test the performance of the method. The results show that, for both the datasets, the spectra can be correctly predicted using the transferred partial least squares (PLS) models. Because standard samples are not necessary in the method, it may be more useful in practical uses. PMID:27380302

  11. Assessment of measurement errors and dynamic calibration methods for three different tipping bucket rain gauges

    Science.gov (United States)

    Shedekar, Vinayak S.; King, Kevin W.; Fausey, Norman R.; Soboyejo, Alfred B. O.; Harmel, R. Daren; Brown, Larry C.

    2016-09-01

    Three different models of tipping bucket rain gauges (TBRs), viz. HS-TB3 (Hydrological Services Pty Ltd.), ISCO-674 (Isco, Inc.) and TR-525 (Texas Electronics, Inc.), were calibrated in the lab to quantify measurement errors across a range of rainfall intensities (5 mm·h- 1 to 250 mm·h- 1) and three different volumetric settings. Instantaneous and cumulative values of simulated rainfall were recorded at 1, 2, 5, 10 and 20-min intervals. All three TBR models showed a substantial deviation (α = 0.05) in measurements from actual rainfall depths, with increasing underestimation errors at greater rainfall intensities. Simple linear regression equations were developed for each TBR to correct the TBR readings based on measured intensities (R2 > 0.98). Additionally, two dynamic calibration techniques, viz. quadratic model (R2 > 0.7) and T vs. 1/Q model (R2 = > 0.98), were tested and found to be useful in situations when the volumetric settings of TBRs are unknown. The correction models were successfully applied to correct field-collected rainfall data from respective TBR models. The calibration parameters of correction models were found to be highly sensitive to changes in volumetric calibration of TBRs. Overall, the HS-TB3 model (with a better protected tipping bucket mechanism, and consistent measurement errors across a range of rainfall intensities) was found to be the most reliable and consistent for rainfall measurements, followed by the ISCO-674 (with susceptibility to clogging and relatively smaller measurement errors across a range of rainfall intensities) and the TR-525 (with high susceptibility to clogging and frequent changes in volumetric calibration, and highly intensity-dependent measurement errors). The study demonstrated that corrections based on dynamic and volumetric calibration can only help minimize-but not completely eliminate the measurement errors. The findings from this study will be useful for correcting field data from TBRs; and may have major

  12. A fast and simple method for calibrating the flip angle in hyperpolarized 13C MRS experiments

    DEFF Research Database (Denmark)

    Giovannetti, Giulio; Frijia, Francesca; Flori, Alessandra;

    2015-01-01

    of technological problems still limits this technology and needs innovative solutions. In particular, the optimization of the signalto-noise ratio during the acquisitions requires the use of pulse sequences with accurate flip angle calibration, which is performed by adjusting the transmit power in the prescan step....... This is even more critical in the case of hyperpolarized studies, because the fast decay of the hyperpolarized signal requires precise determination of the flip angle for the acquisition. This work describes a fast and efficient procedure for transmit power calibration of magnetic resonance acquisitions...

  13. Dual Heat Pulse, Dual Layer Thermal Protection System Sizing Analysis and Trade Studies for Human Mars Entry Descent and Landing

    Science.gov (United States)

    McGuire, Mary Kathleen

    2011-01-01

    NASA has been recently updating design reference missions for the human exploration of Mars and evaluating the technology investments required to do so. The first of these started in January 2007 and developed the Mars Design Reference Architecture 5.0 (DRA5). As part of DRA5, Thermal Protection System (TPS) sizing analysis was performed on a mid L/D rigid aeroshell undergoing a dual heat pulse (aerocapture and atmospheric entry) trajectory. The DRA5 TPS subteam determined that using traditional monolithic ablator systems would be mass expensive. They proposed a new dual-layer TPS concept utilizing an ablator atop a low thermal conductivity insulative substrate to address the issue. Using existing thermal response models for an ablator and insulative tile, preliminary hand analysis of the dual layer concept at a few key heating points indicated that the concept showed potential to reduce TPS masses and warranted further study. In FY09, the followon Entry, Descent and Landing Systems Analysis (EDL-SA) project continued by focusing on Exploration-class cargo or crewed missions requiring 10 to 50 metric tons of landed payload. The TPS subteam advanced the preliminary dual-layer TPS analysis by developing a new process and updated TPS sizing code to rapidly evaluate mass-optimized, full body sizing for a dual layer TPS that is capable of dual heat pulse performance. This paper describes the process and presents the results of the EDL-SA FY09 dual-layer TPS analyses on the rigid mid L/D aeroshell. Additionally, several trade studies were conducted with the sizing code to evaluate the impact of various design factors, assumptions and margins.

  14. TU-A-18A-01: Basic Principles of PET/CT, Calibration Methods and Contrast Recovery Across Multiple Cameras

    Energy Technology Data Exchange (ETDEWEB)

    Kappadath, S [UT MD Anderson Cancer Center, Houston, TX (United States); Nye, J [Emory University, Atlanta, GA (United States)

    2014-06-15

    This continuing education session will discuss the physical principles of PET/CT imaging and characterization of contrast recovery using accreditation phantoms. A detailed overview will be given on the physical principles of PET including positron decay physics, 2D and 3D data acquisition, time-of-flight, scatter correction, CT attenuation correction, and image reconstruction. Instrument quality control and calibration procedures will be discussed. Technical challenges, common image artifacts and strategies to mitigate these issues will also be discussed. Data will be presented on acquisition techniques and reconstruction parameters affecting contrast recovery. The discussion will emphasize the minimization of reconstruction differences in quantification metrics such as SUV and contrast recovery coefficients for the NEMA and ACR clinical trial phantoms. Data from new and older generation scanners will be shown including comparison of contrast recovery measurements to their analytical solutions. The goal of this session is to update attendees on the quality control and calibration of PET/CT scanners, on methods to establish a common calibration for PET/CT scanners to control for instrument variance across multiple sites. Learning Objectives: Review the physical principles of PET/CT, quality control and calibration Gain further understanding on how to apply techniques for improving quantitative agreement across multiple cameras Describe the differences between measured and expected contrast recovery for the NEMA and ACR PET phantoms.

  15. Application of the Langley plot method to the calibration of the solar backscattered ultraviolet instrument on the Nimbus 7 satellite

    Science.gov (United States)

    Bhartia, P. K.; Taylor, S.; Mcpeters, R. D.; Wellemeyer, C.

    1995-01-01

    The concept of the well-known Langley plot technique, used for the calibration of ground-based instruments, has been generalized for application to satellite instruments. In polar regions, near summer solstice, the solar backscattered ultraviolet (SBUV) instrument on the Nimbus 7 satellite samples the same ozone field at widely different solar zenith angles. These measurements are compared to assess the long-term drift in the instrument calibration. Although the technique provides only a relative wavelength-to-wavelength calibration, it can be combined with existing techniques to determine the drift of the instrument at any wavelength. Using this technique, we have generated a 12-year data set of ozone vertical profiles from SBUV with an estimated accuracy of +/- 5% at 1 mbar and +/- 2% at 10 mbar (95% confidence) over 12 years. Since the method is insensitive to true changes in the atmospheric ozone profile, it can also be used to compare the calibrations of similar SBUV instruments launched without temporal overlap.

  16. An innovative method for {sup 192}Ir HDR calibration by farmer chamber, V-film, and solid phantom

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Liyun; Ding, Hueisch-Jy [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Ho, Sheng-Yow, E-mail: shengho@seed.net.tw [Department of Radiation Oncology, Sinlau Christian Hospital, Tainan, Taiwan (China)

    2011-08-01

    A simple, practical and economical technique was proposed to calibrate an {sup 192}Ir HDR brachytherapy source in terms of air kerma strength. This technique makes use of the 0.6 cm{sup 3} Farmer type ion chamber, radiographic film and polystyrene phantom. These tools are commonly used for dosimetry quality assurance of the clinical linear accelerator. In this study, the Exradin A19, PTW N30004 and TM30001 Farmer type ion chambers were used for the calibration of the {sup 192}Ir HDR source. To perform the calibration, a 25.4x30.5 cm{sup 2} radiographic film was taped on a piece of polystyrene plate, and a straight applicator probe of a HDR brachytherapy unit and the Farmer type ion chamber were affixed to the film envelope. The film was irradiated by the {sup 192}Ir source, followed by an exposure in the simulator X-ray beam. The film set with the film removed was then placed on a 5 cm thick polystyrene phantom for calibration measurement. Based on the electrometer reading from the Farmer type ion chamber irradiated by {sup 192}Ir and the measured source-to-chamber distance by means of the images on the developed film, we can calculate the air kerma strength of the {sup 192}Ir using the new technique. Our calibration results were compared to the data provided by the manufacturer and that of five different well type ion chambers, namely, Sun Nuclear cooperation (SNC) 1008, Nucletron SDS 077.091, SDS 077.094, PTW TN33004 and Standard Imaging (SI) HDR-1000 Plus. The differences were all within 1.6%. Relative to the '7-distance measurement technique' by Stump et al., 2002, our method is more efficient if our empirical formula was used. In summary, our method is simpler and cost-effective to calibrate an {sup 192}Ir HDR brachytherapy source for those hospitals without a calibration jig or a well type ion chamber.

  17. In-situ calibration of large heat meters in district heating plants by means of radioisotope flow measuring methods

    International Nuclear Information System (INIS)

    The growing use of district heating network requires a reliable system of calibrated heat meters. Radioactive tracer techniques enable such control and calibration. The standardized methods of liquid flow measuring by means of radioisotope injection are described in ISO Standards 2975/VII and 555/3. The measurement consists in isotope dilution determination in hot water samples, rather than in determination of the flow rate which requires a long distance between the injection and testing point on the heat distribution pipeline. The development project aims at modification and construction of specialized equipment for radioisotopic calibration measurements of large heat meters according to the flow-rate method and dilution method. Testing of the method efficiency is based on comparison with reference measurements of the Danish Technological Institute. Instrumentation is described in detail in the Appendix. All the stages from tracer dosing for injections to the determination of the tracer in the final extracted sample are automatically controlled by a PC software, not included in this report. (EG)

  18. Calculation of depth-dependent elemental concentration with X-ray fluorescence using a layered calibration method

    Science.gov (United States)

    Gherase, M. R.; Fleming, D. E. B.

    2011-05-01

    Depth-dependent elemental concentration can be assessed using either multiple-angle or confocal X-ray fluorescence (XRF) measurements. This work presents a different approach based on a layered calibration method. The depth-dependent elemental concentration was modeled as multiple layers of uniform elemental concentrations. The unknown elemental concentration in each layer can be calculated using a single-angle XRF measurement, layered calibration data, and a priori knowledge of the concentration behavior as a function of depth. The method was verified using a commercial portable X-ray spectrometer and four-layer stacks of polyester resin discs doped with various concentrations of arsenic. This approach is particularly suitable for quantitative in vivo measurements of arsenic and selenium concentrations in the human skin since minimal ionizing radiation exposure constrains the number of XRF measurements.

  19. 糖化血红蛋白分析仪的校准方法%Calibration Method of Glycosylated Hemoglobin

    Institute of Scientific and Technical Information of China (English)

    万卓

    2015-01-01

    This article summarizes up the calibration method of Glycosylated Hemoglobin, and the procedure of the evaluation of measurement uncertainty on detection result was described in detail.%本文阐述了糖化血红蛋白分析仪的校准方法,并对测量结果示值误差的不确定度评定过程进行了详细描述。

  20. Simultaneous Detemination of Atorvastatin Calcium and Amlodipine Besylate by Spectrophotometry and Multivariate Calibration Methods in Pharmaceutical Formulations

    OpenAIRE

    Amir H. M. Sarrafi; Elahe Konoz; Maryam Ghiyasvand

    2011-01-01

    Resolution of binary mixture of atorvastatin (ATV) and amlodipine (AML) with minimum sample pretreatment and without analyte separation has been successfully achieved using a rapid method based on partial least square analysis of UV–spectral data. Multivariate calibration modeling procedures, traditional partial least squares (PLS-2), interval partial least squares (iPLS) and synergy partial least squares (siPLS), were applied to select a spectral range that provided the lowest prediction err...

  1. New Calibration Method Using Low Cost MEM IMUs to Verify the Performance of UAV-Borne MMS Payloads

    Directory of Open Access Journals (Sweden)

    Kai-Wei Chiang

    2015-03-01

    Full Text Available Spatial information plays a critical role in remote sensing and mapping applications such as environment surveying and disaster monitoring. An Unmanned Aerial Vehicle (UAV-borne mobile mapping system (MMS can accomplish rapid spatial information acquisition under limited sky conditions with better mobility and flexibility than other means. This study proposes a long endurance Direct Geo-referencing (DG-based fixed-wing UAV photogrammetric platform and two DG modules that each use different commercial Micro-Electro Mechanical Systems’ (MEMS tactical grade Inertial Measurement Units (IMUs. Furthermore, this study develops a novel kinematic calibration method which includes lever arms, boresight angles and camera shutter delay to improve positioning accuracy. The new calibration method is then compared with the traditional calibration approach. The results show that the accuracy of the DG can be significantly improved by flying at a lower altitude using the new higher specification hardware. The new proposed method improves the accuracy of DG by about 20%. The preliminary results show that two-dimensional (2D horizontal DG positioning accuracy is around 5.8 m at a flight height of 300 m using the newly designed tactical grade integrated Positioning and Orientation System (POS. The positioning accuracy in three-dimensions (3D is less than 8 m.

  2. New calibration method using low cost MEM IMUs to verify the performance of UAV-borne MMS payloads.

    Science.gov (United States)

    Chiang, Kai-Wei; Tsai, Meng-Lun; Naser, El-Sheimy; Habib, Ayman; Chu, Chien-Hsun

    2015-03-19

    Spatial information plays a critical role in remote sensing and mapping applications such as environment surveying and disaster monitoring. An Unmanned Aerial Vehicle (UAV)-borne mobile mapping system (MMS) can accomplish rapid spatial information acquisition under limited sky conditions with better mobility and flexibility than other means. This study proposes a long endurance Direct Geo-referencing (DG)-based fixed-wing UAV photogrammetric platform and two DG modules that each use different commercial Micro-Electro Mechanical Systems' (MEMS) tactical grade Inertial Measurement Units (IMUs). Furthermore, this study develops a novel kinematic calibration method which includes lever arms, boresight angles and camera shutter delay to improve positioning accuracy. The new calibration method is then compared with the traditional calibration approach. The results show that the accuracy of the DG can be significantly improved by flying at a lower altitude using the new higher specification hardware. The new proposed method improves the accuracy of DG by about 20%. The preliminary results show that two-dimensional (2D) horizontal DG positioning accuracy is around 5.8 m at a flight height of 300 m using the newly designed tactical grade integrated Positioning and Orientation System (POS). The positioning accuracy in three-dimensions (3D) is less than 8 m.

  3. New calibration method using low cost MEM IMUs to verify the performance of UAV-borne MMS payloads.

    Science.gov (United States)

    Chiang, Kai-Wei; Tsai, Meng-Lun; Naser, El-Sheimy; Habib, Ayman; Chu, Chien-Hsun

    2015-01-01

    Spatial information plays a critical role in remote sensing and mapping applications such as environment surveying and disaster monitoring. An Unmanned Aerial Vehicle (UAV)-borne mobile mapping system (MMS) can accomplish rapid spatial information acquisition under limited sky conditions with better mobility and flexibility than other means. This study proposes a long endurance Direct Geo-referencing (DG)-based fixed-wing UAV photogrammetric platform and two DG modules that each use different commercial Micro-Electro Mechanical Systems' (MEMS) tactical grade Inertial Measurement Units (IMUs). Furthermore, this study develops a novel kinematic calibration method which includes lever arms, boresight angles and camera shutter delay to improve positioning accuracy. The new calibration method is then compared with the traditional calibration approach. The results show that the accuracy of the DG can be significantly improved by flying at a lower altitude using the new higher specification hardware. The new proposed method improves the accuracy of DG by about 20%. The preliminary results show that two-dimensional (2D) horizontal DG positioning accuracy is around 5.8 m at a flight height of 300 m using the newly designed tactical grade integrated Positioning and Orientation System (POS). The positioning accuracy in three-dimensions (3D) is less than 8 m. PMID:25808764

  4. An Easy Calibration Method for Central Catadioptric Cameras%一种反射折射摄像机的简易标定方法

    Institute of Scientific and Technical Information of China (English)

    邓小明; 吴福朝; 吴毅红

    2007-01-01

    Central catadioptric cameras are widely used in virtual reality and robot navigation, and the camera calibration is a prerequisite for these applications. In this paper, we propose an easy calibration method for central catadioptric cameras with a 2D calibration pattern. Firstly, the bounding ellipse of the catadioptric image and field of view (FOV) are used to obtain the initial estimation of the intrinsic parameters. Then, the explicit relationship between the central catadioptric and the pinhole model is used to initialize the extrinsic parameters. Finally, the intrinsic and extrinsic parameters are refined by nonlinear optimization. The proposed method does not need any fitting of partial visible conic, and the projected images of 2D calibration pattern can easily cover the whole image, so our method is easy and robust. Experiments with simulated data as well as real images show the satisfactory performance of our proposed calibration method.

  5. White-light Interferometry using a Channeled Spectrum: II. Calibration Methods, Numerical and Experimental Results

    Science.gov (United States)

    Zhai, Chengxing; Milman, Mark H.; Regehr, Martin W.; Best, Paul K.

    2007-01-01

    In the companion paper, [Appl. Opt. 46, 5853 (2007)] a highly accurate white light interference model was developed from just a few key parameters characterized in terms of various moments of the source and instrument transmission function. We develop and implement the end-to-end process of calibrating these moment parameters together with the differential dispersion of the instrument and applying them to the algorithms developed in the companion paper. The calibration procedure developed herein is based on first obtaining the standard monochromatic parameters at the pixel level: wavenumber, phase, intensity, and visibility parameters via a nonlinear least-squares procedure that exploits the structure of the model. The pixel level parameters are then combined to obtain the required 'global' moment and dispersion parameters. The process is applied to both simulated scenarios of astrometric observations and to data from the microarcsecond metrology testbed (MAM), an interferometer testbed that has played a prominent role in the development of this technology.

  6. A D-optimal Multi-position Calibration Method for Dynamically Tuned Gyroscopes

    Institute of Scientific and Technical Information of China (English)

    FU Li; ZHU Yongquan; WANG Lingling; WANG Xinling

    2011-01-01

    This paper presents a novel experimental design to greatly improve the calibration accuracy of the acceleration-insensitive bias and the acceleration-sensitive bias of the dynamically tuned gyroscopes (DTGs). In order to reduce experimental cost, the D-optimal criteria with constraints are constructed. The turntable positions and the number of test points are chosen to build D-optimal experimental designs. The D-optimal experimental designs are tested by multi-position calibration experiment for tactical-grade DTGs. Test results show that, with the same cost, the fit uncertainty is reduced by about 50% by using the D-optimal 8-position experimental procedure, compared to using a defacto standard experimental procedure in ANSI/IEEE Std 813-1988. Furthermore, the new experimental procedure almost achieves optimal accuracy with only 12-position which is half the cost of the widely adopted 24-position experimental procedure for achieving optimal accuracy.

  7. New method for the time calibration of an interferometric radio antenna array

    CERN Document Server

    Schröder, F G; Bähren, L; Blümer, J; Bozdog, H; Falcke, H; Haungs, A; Horneffer, A; Huege, T; Isar, P G; Krömer, O; Nehls, S; 10.1016/j.nima.2010.01.072

    2010-01-01

    Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative del...

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

    OpenAIRE

    Zheng You; Fei Xing; Ting Sun

    2013-01-01

    The star tracker is a high-accuracy attitude measurement device widely used in spacecraft. Its performance depends largely on the precision of the optical system parameters. Therefore, the analysis of the optical system parameter errors and a precise calibration model are crucial to the accuracy of the star tracker. Research in this field is relatively lacking a systematic and universal analysis up to now. This paper proposes in detail an approach for the synthetic error analysis of the star ...

  9. Improvements on the directional characteristics of a calibration sound source using the Boundary Element Method

    DEFF Research Database (Denmark)

    Henriquez, Vicente Cutanda; Barrera Figueroa, Salvador; Juhl, Peter Møller

    2008-01-01

    been used to modify the source and make it suitable for this kind of calibration. It has been found that a central plug, already present in the device, can be re-shaped in such a way that makes the sound field on the microphone positions more uniform, even at rather high frequencies. Measurements have...... been carried out in order to verify the goodness of this solution....

  10. A novel method to calibrate DOI function of a PET detector with a dual-ended-scintillator readout.

    Science.gov (United States)

    Shao, Yiping; Yao, Rutao; Ma, Tianyu

    2008-12-01

    The detection of depth-of-interaction (DOI) is a critical detector capability to improve the PET spatial resolution uniformity across the field-of-view and will significantly enhance, in particular, small bore system performance for brain, breast, and small animal imaging. One promising technique of DOI detection is to use dual-ended-scintillator readout that uses two photon sensors to detect scintillation light from both ends of a scintillator array and estimate DOI based on the ratio of signals (similar to Anger logic). This approach needs a careful DOI function calibration to establish accurate relationship between DOI and signal ratios, and to recalibrate if the detection condition is shifted due to the drift of sensor gain, bias variations, or degraded optical coupling, etc. However, the current calibration method that uses coincident events to locate interaction positions inside a single scintillator crystal has severe drawbacks, such as complicated setup, long and repetitive measurements, and being prone to errors from various possible misalignments among the source and detector components. This method is also not practically suitable to calibrate multiple DOI functions of a crystal array. To solve these problems, a new method has been developed that requires only a uniform flood source to irradiate a crystal array without the need to locate the interaction positions, and calculates DOI functions based solely on the uniform probability distribution of interactions over DOI positions without knowledge or assumption of detector responses. Simulation and experiment have been studied to validate the new method, and the results show that the new method, with a simple setup and one single measurement, can provide consistent and accurate DOI functions for the entire array of multiple scintillator crystals. This will enable an accurate, simple, and practical DOI function calibration for the PET detectors based on the design of dual-ended-scintillator readout. In

  11. Validation of the onboard radiometric calibration of the GOES I-M visible channel by reflectance-based vicarious methods

    Science.gov (United States)

    Leisso, Nathan P.; Thome, Kurtis J.; Czapla-Myers, Jeffrey S.

    2007-09-01

    The current generation of the Geostationary Operations Environmental Satellite (GOES) platform employs a total of 5 sensors to monitor and record atmospheric conditions used in predictions of upcoming weather events. Included in this package is a 5-band imager that, from the 36,000-km geosynchronous orbit inhabited by GOES platform, enables multiple fixed full-disc surface images of the earth during the course of a 24-hour day. There is currently no on-board radiometric calibration for the visible bands of the imager and radiometric calibration relies on vicarious approaches. The Remote Sensing Group (RSG) at the University of Arizona uses a vicarious approach that relies on ground-based measurements to determine the radiometric calibration for multiple sun-synchronous and airborne visible and near-infrared sensors. The current work extends the approach to the GOES I-M series of sensor. The paper presents the methods and results of the reflectance-based method applied to the 1-km visible channel of GOES-11using large North American high-desert test sites. Modifications to the RSG's methods to take into account the location of the test sites at large zenith angles within the full-disk GOES image. The work provides an opportunity to evaluate uncertainties of the spectral BRF of the test sites at large view angles and resulting importance to the accurate radiometric calibration of a sensor. In addition, the impact of increased path length caused by the large view angle is evaluated with an emphasis on the increased effect of the atmospheric characterization.

  12. Spiral reader calibration

    International Nuclear Information System (INIS)

    The method to calibrate the spiral reader (SR) is presented. A brief description of the main procedures of the calibration program SCALP, adapted for the IHEP equipment and purposes, is described. The precision characteristics of the IHEP SR have been analysed on the results, presented in the form of diagrams. There is a calibration manual for the user

  13. Hyper-Cam automated calibration method for continuous hyperspectral imaging measurements

    Science.gov (United States)

    Gagnon, Jean-Philippe; Habte, Zewdu; George, Jacks; Farley, Vincent; Tremblay, Pierre; Chamberland, Martin; Romano, Joao; Rosario, Dalton

    2010-04-01

    The midwave and longwave infrared regions of the electromagnetic spectrum contain rich information which can be captured by hyperspectral sensors thus enabling enhanced detection of targets of interest. A continuous hyperspectral imaging measurement capability operated 24/7 over varying seasons and weather conditions permits the evaluation of hyperspectral imaging for detection of different types of targets in real world environments. Such a measurement site was built at Picatinny Arsenal under the Spectral and Polarimetric Imagery Collection Experiment (SPICE), where two Hyper-Cam hyperspectral imagers are installed at the Precision Armament Laboratory (PAL) and are operated autonomously since Fall of 2009. The Hyper-Cam are currently collecting a complete hyperspectral database that contains the MWIR and LWIR hyperspectral measurements of several targets under day, night, sunny, cloudy, foggy, rainy and snowy conditions. The Telops Hyper-Cam sensor is an imaging spectrometer that enables the spatial and spectral analysis capabilities using a single sensor. It is based on the Fourier-transform technology yielding high spectral resolution and enabling high accuracy radiometric calibration. It provides datacubes of up to 320x256 pixels at spectral resolutions of up to 0.25 cm-1. The MWIR version covers the 3 to 5 μm spectral range and the LWIR version covers the 8 to 12 μm spectral range. This paper describes the automated operation of the two Hyper-Cam sensors being used in the SPICE data collection. The Reveal Automation Control Software (RACS) developed collaboratively between Telops, ARDEC, and ARL enables flexible operating parameters and autonomous calibration. Under the RACS software, the Hyper-Cam sensors can autonomously calibrate itself using their internal blackbody targets, and the calibration events are initiated by user defined time intervals and on internal beamsplitter temperature monitoring. The RACS software is the first software developed for

  14. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors.

    Science.gov (United States)

    Waugh, C J; Rosenberg, M J; Zylstra, A B; Frenje, J A; Séguin, F H; Petrasso, R D; Glebov, V Yu; Sangster, T C; Stoeckl, C

    2015-05-01

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule. PMID:26026524

  15. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    International Nuclear Information System (INIS)

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule

  16. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    International Nuclear Information System (INIS)

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule

  17. A method for in situ absolute DD yield calibration of neutron time-of-flight detectors on OMEGA using CR-39-based proton detectors

    Energy Technology Data Exchange (ETDEWEB)

    Waugh, C. J., E-mail: cjwaugh@mit.edu; Zylstra, A. B.; Frenje, J. A.; Séguin, F. H.; Petrasso, R. D. [Plasma Science and Fusion Center, MIT, Cambridge, Massachusetts 02139 (United States); Rosenberg, M. J.; Glebov, V. Yu.; Sangster, T. C.; Stoeckl, C. [Laboratory for Laser Energetics, Rochester, New York 14623 (United States)

    2015-05-15

    Neutron time of flight (nTOF) detectors are used routinely to measure the absolute DD neutron yield at OMEGA. To check the DD yield calibration of these detectors, originally calibrated using indium activation systems, which in turn were cross-calibrated to NOVA nTOF detectors in the early 1990s, a direct in situ calibration method using CR-39 range filter proton detectors has been successfully developed. By measuring DD neutron and proton yields from a series of exploding pusher implosions at OMEGA, a yield calibration coefficient of 1.09 ± 0.02 (relative to the previous coefficient) was determined for the 3m nTOF detector. In addition, comparison of these and other shots indicates that significant reduction in charged particle flux anisotropies is achieved when bang time occurs significantly (on the order of 500 ps) after the trailing edge of the laser pulse. This is an important observation as the main source of the yield calibration error is due to particle anisotropies caused by field effects. The results indicate that the CR-39-nTOF in situ calibration method can serve as a valuable technique for calibrating and reducing the uncertainty in the DD absolute yield calibration of nTOF detector systems on OMEGA, the National Ignition Facility, and laser megajoule.

  18. CoMaLit-V. Mass forecasting with proxies. Method and application to weak lensing calibrated samples

    CERN Document Server

    Sereno, Mauro

    2016-01-01

    Mass measurements of astronomical objects are most wanted but still elusive. We need them to trace the formation and evolution of cosmic structure but we can get direct measurements only for a minority. This lack can be circumvented with a proxy and a scaling relation. The twofold goal of estimating the unbiased relation and finding the right proxy value to plug in can be hampered by systematics, selection effects, Eddington/Malmquist biases and time evolution. We present a Bayesian hierarchical method which deals with these issues. Masses to be predicted are treated as missing data in the regression and are estimated together with the scaling parameters. The calibration subsample with measured masses does not need to be representative of the full sample. We apply the method to forecast weak lensing calibrated masses of the Planck, redMaPPer and MCXC clusters. Planck masses are biased low with respect to weak lensing calibrated masses, with a bias more pronounced for high redshift clusters. MCXC masses are un...

  19. A simple method for calibration of Lucas scintillation cell counting system for measurement of 226Ra and 222Rn

    Directory of Open Access Journals (Sweden)

    N.K. Sethy

    2014-10-01

    Full Text Available Known quantity of radium from high grade ore solution was chemically separated and carefully kept inside the cavity of a Lucas Cell (LC. The 222Rn gradually builds up and attain secular equilibrium with its parent 226Ra. This gives a steady count after a suitable buildup period (>25 days. This secondary source was used to calibrate the radon counting system. The method is validated in by comparison with identical measurement with AlphaGuard Aquakit. The radon counting system was used to evaluate dissolved radon in ground water sample by gross alpha counting in LC. Radon counting system measures the collected radon after a delay of >180 min by gross alpha counting. Simultaneous measurement also carried out by AlphaGuard Aquakit in identical condition. AlphaGuard measures dissolved radon from water sample by constant aeration in a closed circuit without giving any delay. Both the methods are matching with a correlation coefficient of >0.9. This validates the calibration of Lucas scintillation cell counting system by designed encapsulated source. This study provides an alternative for calibration in absence of costly Radon source available in the market.

  20. Sparse calibration of subsurface flow models using nonlinear orthogonal matching pursuit and an iterative stochastic ensemble method

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-06-01

    We introduce a nonlinear orthogonal matching pursuit (NOMP) for sparse calibration of subsurface flow models. Sparse calibration is a challenging problem as the unknowns are both the non-zero components of the solution and their associated weights. NOMP is a greedy algorithm that discovers at each iteration the most correlated basis function with the residual from a large pool of basis functions. The discovered basis (aka support) is augmented across the nonlinear iterations. Once a set of basis functions are selected, the solution is obtained by applying Tikhonov regularization. The proposed algorithm relies on stochastically approximated gradient using an iterative stochastic ensemble method (ISEM). In the current study, the search space is parameterized using an overcomplete dictionary of basis functions built using the K-SVD algorithm. The proposed algorithm is the first ensemble based algorithm that tackels the sparse nonlinear parameter estimation problem. © 2013 Elsevier Ltd.

  1. An investigation of the Eigenvalue Calibration Method (ECM) using GASP for non-imaging and imaging detectors

    CERN Document Server

    Kyne, Gillian; Hallinan, Gregg; Redfern, Michael; Shearer, Andrew

    2015-01-01

    Polarised light from astronomical targets can yield a wealth of information about their source radiation mechanisms, and about the geometry of the scattered light regions. Optical observations, of both the linear and circular polarisation components, have been impeded due to non-optimised instrumentation. The need for suitable observing conditions and the availability of luminous targets are also limiting factors. GASP uses division of amplitude polarimeter (DOAP) (Compain and Drevillon) to measure the four components of the Stokes vector simultaneously, which eliminates the constraints placed upon the need for moving parts during observation, and offers a real-time complete measurement of polarisation. Results from the GASP calibration are presented in this work for both a 1D detector system, and a pixel-by-pixel analysis on a 2D detector system. Following Compain et al. we use the Eigenvalue Calibration Method (ECM) to measure the polarimetric limitations of the instrument for each of the two systems. Conse...

  2. A 3D analysis algorithm to improve interpretation of heat pulse sensor results for the determination of small-scale flow directions and velocities in the hyporheic zone

    Science.gov (United States)

    Angermann, Lisa; Lewandowski, Jörg; Fleckenstein, Jan H.; Nützmann, Gunnar

    2012-12-01

    The hyporheic zone is strongly influenced by the adjacent surface water and groundwater systems. It is subject to hydraulic head and pressure fluctuations at different space and time scales, causing dynamic and heterogeneous flow patterns. These patterns are crucial for many biogeochemical processes in the shallow sediment and need to be considered in investigations of this hydraulically dynamic and biogeochemical active interface. For this purpose a device employing heat as an artificial tracer and a data analysis routine were developed. The method aims at measuring hyporheic flow direction and velocity in three dimensions at a scale of a few centimeters. A short heat pulse is injected into the sediment by a point source and its propagation is detected by up to 24 temperature sensors arranged cylindrically around the heater. The resulting breakthrough curves are analyzed using an analytical solution of the heat transport equation. The device was tested in two laboratory flow-through tanks with defined flow velocities and directions. Using different flow situations and sensor arrays the sensitivity of the method was evaluated. After operational reliability was demonstrated in the laboratory, its applicability in the field was tested in the hyporheic zone of a low gradient stream with sandy streambed in NE-Germany. Median and maximum flow velocity in the hyporheic zone at the site were determined as 0.9 × 10-4 and 2.1 × 10-4 m s-1 respectively. Horizontal flow components were found to be spatially very heterogeneous, while vertical flow component appear to be predominantly driven by the streambed morphology.

  3. 双目视觉的立体标定方法%Stereo calibration method of binocular vision

    Institute of Scientific and Technical Information of China (English)

    刘俸材; 谢明红; 王伟

    2011-01-01

    为实现双目视觉系统的立体标定,分析了摄像机成像模型,并充分考虑了透镜的径向畸变和切向畸变,提出了一种新的立体标定算法.该算法利用张正友的灵活标定算法,初步求取摄像机的内参数,结合Brown算法并提取图像中角点的子像素级坐标,精确求取摄像机内参数和畸变向量.为方便后续的图像校正,基于前面的单个摄像机标定,通过计算空间中的景物点在左右摄像机成像平面上盼位置关系,计算出双目视觉系统中两个摄像机之间的旋转矩阵R和平移向量T,从而实现了立体标定.实验结果表明,该算法能取得较高的精度,可以应用于双目视觉系统.%In order to realize stereo calibration for binocular vision system, firstly, the image model of camera with a full consideration of radial distortion and tangential distortion of lens is analyzed, and a new method of stereo calibration is proposed. The flexible calibration method of Zhang Zhengyou is used to achieve the initial value of the camera's intrinsic parameters, and combined with the arithmetic of Brown, sub-pixel coordinates of images' comer point are extracted. Through this method, it calculates the intrinsic parameters and distortion vector accurately. Hereafter, based on the single camera calibration aforementioned and calculation of the position relationship of spatial point projected to the left and right cameras' imaging planes which helps to work out the rotation matrix R and translation vector T between the two cameras of the binocular stereo vision system, finally the stereo calibration is achieved. All experimental results show that this calculation method acquires higher precision, and can be applied to binocular system.

  4. Calibration of the identiFINDER detector for the iodine measurement in thyroid using the Monte Carlo method

    International Nuclear Information System (INIS)

    This work is based on the determination of the detection efficiency of 125I and 131I in thyroid of the identiFINDER detector using the Monte Carlo method. The suitability of the calibration method is analyzed, when comparing the results of the direct Monte Carlo method with the corrected, choosing the latter because the differences with the real efficiency stayed below 10%. To simulate the detector their geometric parameters were optimized using a tomographic study, what allowed the uncertainties minimization of the estimates. Finally were obtained the simulations of the detector geometry-point source to find the correction factors to 5 cm, 15 cm and 25 cm, and those corresponding to the detector-simulator arrangement for the method validation and final calculation of the efficiency, demonstrating that in the Monte Carlo method implementation if simulates at a greater distance than the used in the Laboratory measurements an efficiency overestimation can be obtained, while if simulates at a shorter distance this will be underestimated, so should be simulated at the same distance to which will be measured in the reality. Also, is achieved the obtaining of the efficiency curves and minimum detectable activity for the measurement of 131I and 125I. In general is achieved the implementation of the Monte Carlo methodology for the identiFINDER calibration with the purpose of estimating the measured activity of iodine in thyroid. This method represents an ideal way to replace the lack of patterns solutions and simulators assuring the capacities of the Internal Contamination Laboratory of the Centro de Proteccion e Higiene de las Radiaciones are always calibrated for the iodine measurement in thyroid. (author)

  5. Integration of Tracer Test Data to Refine Geostatistical Hydraulic Conductivity Fields Using Sequential Self-Calibration Method

    Institute of Scientific and Technical Information of China (English)

    Bill X Hu; Jiang Xiaowei; Wan Li

    2007-01-01

    On the basis of local measurements of hydraulic conductivity, geostatistical methods have been found to be useful in heterogeneity characterization of a hydraulic conductivity field on a regional scale. However, the methods are not suited to directly integrate dynamic production data, such as,hydraulic head and solute concentration, into the study of conductivity distribution. These data, which record the flow and transport processes in the medium, are closely related to the spatial distribution of hydraulic conductivity. In this study, a three-dimensional gradient-based inverse method-the sequential self-calibration (SSC) method-is developed to calibrate a hydraulic conductivity field,initially generated by a geostatistical simulation method, conditioned on tracer test results. The SSC method can honor both local hydraulic conductivity measurements and tracer test data. The mismatch between the simulated hydraulic conductivity field and the reference true one, measured by its mean square error (MSE), is reduced through the SSC conditional study. In comparison with the unconditional results, the SSC conditional study creates the mean breakthrough curve much closer to the reference true curve, and significantly reduces the prediction uncertainty of the solute transport in the observed locations. Further, the reduction of uncertainty is spatially dependent, which indicates that good locations, geological structure, and boundary conditions will affect the efficiency of the SSC study results.

  6. Calibration methods of plane-parallel ionization chambers used in electron dosimetry; Metodos de calibracao de camaras de ionizacao de placas paralelas para dosimetria de feixes de eletrons

    Energy Technology Data Exchange (ETDEWEB)

    Bulla, Roseli Tadeu

    1999-07-01

    The use of linear accelerators in radiotherapy is of great importance in Medicine, and according to international recommendations the electron beam dosimetry has to be performed using plane-parallel ionization chambers, previously calibrated in standard gamma radiation fields at accredited laboratories. In this work, calibration methods of plane-parallel ionization chambers used in dosimetry procedures of high energy electron beams of clinical accelerators were presented, tested and intercompared. The experiments were carried out using gamma radiation beams of {sup 60} Co at the Calibration Laboratory of Clinical Dosemeters at IPEN and electron beams od 4 to 16 MeV at the Radiotherapy Department of Hospital Israelita Albert Einstein, Sao Paulo. A method was chosen to be established at IPEN. Proposals of the calibration procedure, calibration certificate and data sheets are presented. (author)

  7. New method for the time calibration of an interferometric radio antenna array

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, F.G., E-mail: frank.schroeder@kit.ed [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Asch, T. [Karlsruhe Institute of Technology (KIT), Institut fuer Prozessdatenverarbeitung und Elektronik, 76021 Karlsruhe (Germany); Baehren, L. [Radboud University Nijmegen, Department of Astrophysics, 6525 ED Nijmegen (Netherlands); Bluemer, J. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Karlsruhe Institute of Technology (KIT), Institut fuer Experimentelle Kernphysik, 76021 Karlsruhe (Germany); Bozdog, H. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Falcke, H. [Radboud University Nijmegen, Department of Astrophysics, 6525 ED Nijmegen (Netherlands); ASTRON, 7990 AA Dwingeloo (Netherlands); Haungs, A. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Horneffer, A. [Radboud University Nijmegen, Department of Astrophysics, 6525 ED Nijmegen (Netherlands); Huege, T.; Isar, P.G. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany); Kroemer, O. [Karlsruhe Institute of Technology (KIT), Institut fuer Prozessdatenverarbeitung und Elektronik, 76021 Karlsruhe (Germany); Nehls, S. [Karlsruhe Institute of Technology (KIT), Institut fuer Kernphysik, 76021 Karlsruhe (Germany)

    2010-04-11

    Digital radio antenna arrays, like LOPES (LOFAR PrototypE Station), detect high-energy cosmic rays via the radio emission from atmospheric extensive air showers. LOPES is an array of dipole antennas placed within and triggered by the KASCADE-Grande experiment on site of the Karlsruhe Institute of Technology, Germany. The antennas are digitally combined to build a radio interferometer by forming a beam into the air shower arrival direction which allows measurements even at low signal-to-noise ratios in individual antennas. This technique requires a precise time calibration. A combination of several calibration steps is used to achieve the necessary timing accuracy of about 1 ns. The group delays of the setup are measured, the frequency dependence of these delays (dispersion) is corrected in the subsequent data analysis, and variations of the delays with time are monitored. We use a transmitting reference antenna, a beacon, which continuously emits sine waves at known frequencies. Variations of the relative delays between the antennas can be detected and corrected for at each recorded event by measuring the phases at the beacon frequencies.

  8. The Research of Through-casing Resistivity Logging Logging Calibration System Leakage Current Measurement Method

    Directory of Open Access Journals (Sweden)

    ZHANG Jiatian

    2013-07-01

    Full Text Available This paper introduces the logging principle of through-casing resistivity logging technology, finds a phenomenon that the leakage current measurements are susceptible to sufferring interferences. The through-casing resistivity logging technology in Russia and that of Schlumberger are studied, and the system of through-casing resistivity logging is established to improve the accuracy of calibrating, testing and measuring of the instrument. In this paper, distribution parameters of the form is replaced by the lumped parameter, and precision resistor array simulation in formation leakage current and scale pool simulation in different resistivity of formation are conducted, which make the dynamic range of the simulation in formation resistivity of the medium increase to 1- 300 Ω·m and meet the requirement of through-casing resistivity logging technology measurement range, 1 Ω·m ~ 100 Ω·m. Since the measuring signals of calibration acquisition and processing systems are extremely weak and calculation signals need to tell the nV (nanovolts level, the high accurate data acquisition system of 24 digits is applied.

  9. Calibration of Ge(Li) semiconductor detector by method using agar volume source

    International Nuclear Information System (INIS)

    The Ge(Li) semiconductor detector was calibrated for measurements of environmental samples. The radioisotopes used for standard sources are 22Na, 51Cr, 56Co, 57Co, 133Ba, 137Cs, 144Ce and 241Am. These are mixed with hot agar aqueous solution and fixed uniformly in a cylindrical plastic case in cooling. The agar volume source is advantageous in handling over the fluid aqueous source. The prepared cylindrical standard sources are in diameters 6 and 8 cm and thicknesses 1, 5, 10, 20, 30 and 40 mm (only for 8 cm diameter). The radioactivities of prepared standard sources are between 0.03 μCi and 0.2 μCi. It takes only a week to make the calibration except data processing. The obtained full energy peak efficiency curves include 5 - 10% error due to preparation of agar source, reference radioactivity data of purchased standard solutions, reference data of branching ratio of gamma-ray and sum effect. The efficiency curves, however, are sufficient for quantitative analysis of environmental samples. (author)

  10. Comparison between calibration methods of kerma-area product (P{sub KA}); Comparacao entre metodos de calibracao do produto kerma-area (P{sub KA})

    Energy Technology Data Exchange (ETDEWEB)

    Navarro, V.C.C.; Macedo, E.M.; Pereira, L.C.S.; Modesto, I.F.; Ferreira, M.; Navarro, M.V.T., E-mail: valeria@ifba.edu.br [Instituto Federal da Bahia (LABPROSAUD/IFBA), Salvador, BA (Brazil). Laboratorio de Produtos para a Saude

    2015-07-01

    P{sub KA} is a relevant dosimetric quantity utilized mainly in interventional radiology procedures, and it's calibration essential for maintenance of the metrological reliability in measurements. As there are two methods to calibrate this kind of meters (substitution method and directly measuring kerma and area), the goal of this study was to compare them, in order to indicate which is the better option to be implanted at Calibration Laboratory Labprosaud/IFBA. The results showed a good equivalence between two methods, with minimal concordance of 99,2% between calibration factors. However, the substitution method ensure higher metrological reliability with uncertainties 60% lower. This method was implanted at Labprosaud. (author)

  11. Electric field measurement using a non-perturbative method based on a calibrated electric potential sensor

    Energy Technology Data Exchange (ETDEWEB)

    Aydin, A; Stiffell, P B, E-mail: a.aydin@sussex.ac.uk [Centre for Physical Electronics and Quantum Technology, School of Engineering and Design, University of Sussex, Brighton, BN1 9QT (United Kingdom)

    2011-06-23

    We present results of finite element analysis for simple test structures which demonstrate clearly that the measurement situation is complex. The test structure consists of an open geometry parallel plate capacitor within a screened enclosure. Indeed, the presence of earthed objects, even at considerable distances, is shown to have a significant effect on the field geometry close to the source. These simulations are compared with field measurements made using an ultra-high input impedance sensor, the Electric Potential Sensor. A single experimentally determined calibration factor is all that is required to achieve excellent agreement between experimental measurements and the results of the simulations. Given this, the sensor is capable of mapping accurately, and in a non-perturbative manner, the spatial potential both within and outside of the test structure.

  12. New method for atmospheric calibration at the Pierre Auger Observatory using FRAM, a robotic astronomical telescope

    CERN Document Server

    BenZvi, Segev; Connolly, Brian; Grygar, Jiri; Hrabovsky, Miroslav; Karova, Tatiana; Mandat, Dusan; Necesal, Petr; Nosek, Dalibor; Nozka, Libor; Palatka, Miroslav; Pech, Miroslav; Prouza, Michael; Ridky, Jan; Schovanek, Petr; Smida, Radomir; Travnicek, Petr; Vitale, Primo; Westerhoff, Stefan

    2007-01-01

    FRAM - F/(Ph)otometric Robotic Atmospheric Monitor is the latest addition to the atmospheric monitoring instruments of the Pierre Auger Observatory. An optical telescope equipped with CCD camera and photometer, it automatically observes a set of selected standard stars and a calibrated terrestrial source. Primarily, the wavelength dependence of the attenuation is derived and the comparison between its vertical values (for stars) and horizontal values (for the terrestrial source) is made. Further, the integral vertical aerosol optical depth can be obtained. A secondary program of the instrument, the detection of optical counterparts of gamma-ray bursts, has already proven successful. The hardware setup, software system, data taking procedures, and first analysis results are described in this paper.

  13. New method for atmospheric calibration at the Pierre Auger Observatory using FRAM, a robotic astronomical telescope

    Science.gov (United States)

    Trávníček, Petr; Benzvi, Segev; Boháčová, Martina; Connolly, Brian; Grygar, Jiří; Hrabovský, Miroslav; Kárová, Tatiana; Mandát, Dušan; Nečesal, Petr; Nosek, Dalibor; Nožka, Libor; Palatka, Miroslav; sPech, Miroslav; Prouza, Michael; Řídký, Jan; Schovánek, Petr; Šmída, Radomír; Vitale, Primo; Westerhoff, Stefan

    FRAM - F/(Ph)otometric Robotic Atmospheric Monitor is the latest addition to the atmospheric monitoring instruments of the Pierre Auger Observatory. An optical telescope equipped with CCD camera and photometer, it automatically observes a set of selected standard stars and a calibrated terrestrial source. Primarily, the wavelength dependence of the attenuation is derived and the comparison between its vertical values (for stars) and horizontal values (for the terrestrial source) is made. Further, the integral vertical aerosol optical depth can be obtained. A secondary program of the instrument, the detection of optical counterparts of gamma-ray bursts, has already proven successful. The hardware setup, software system, data taking procedures, and first analysis results are described in this paper.

  14. In situ spectral calibration method for the impurity influx monitor (divertor) for ITER using angled physical contact fibers.

    Science.gov (United States)

    Iwamae, A; Ogawa, H; Sugie, T; Kusama, Y

    2011-03-01

    The in situ calibration method for the impurity influx monitor (divertor) is experimentally examined. The total reflectance of the optical path from the focal point of the Cassegrain telescope to the first mirror is derived using a micro retroreflector array. An optical fiber with angled physical contact (APC) connectors reduces the return edge reflection. APC fibers and a multimode coupler increase the signal-to-noise ratio by about one order compared to that of triple-branched fibers and enable measurement of the wavelength dependence of the total reflectance of the optical system even after potential deterioration of mirror surfaces reduces reflectance.

  15. A simple method for calibration of Lucas scintillation cell counting system for measurement of 226Ra and 222Rn

    OpenAIRE

    N.K. Sethy; V.N. Jha; P.M. Ravi; Tripathi, R. M.

    2014-01-01

    Known quantity of radium from high grade ore solution was chemically separated and carefully kept inside the cavity of a Lucas Cell (LC). The 222Rn gradually builds up and attain secular equilibrium with its parent 226Ra. This gives a steady count after a suitable buildup period (>25 days). This secondary source was used to calibrate the radon counting system. The method is validated in by comparison with identical measurement with AlphaGuard Aquakit. The radon counting system was used to eva...

  16. Application of the Gamma Spectrometry Sourceless Efficiency Calibration Method to the Measurement of Radionuclides in Rare Earth Residues

    International Nuclear Information System (INIS)

    The paper investigates and analyses NORM residues from rare earth smelting and separation plants in Jiangsu Province using the high purity germanium gamma spectrometry sourceless efficiency calibration method which was verified by IAEA reference materials. The results show that in the rare earth residues the radioactive equilibrium of uranium and thorium decay series has been broken and the activity concentrations in the samples have obvious differences. Based on the results, the paper makes some suggestions and proposes some protective measures for the disposal of rare earth residues. (author)

  17. An Inexpensive Method for Kinematic Calibration of a Parallel Robot by Using One Hand-Held Camera as Main Sensor

    OpenAIRE

    Ricardo Carelli; Eduardo Castillo; Jesús Torrijos; José María Sebastián; Alberto Traslosheros

    2013-01-01

    This paper presents a novel method for the calibration of a parallel robot, which allows a more accurate configuration instead of a configuration based on nominal parameters. It is used, as the main sensor with one camera installed in the robot hand that determines the relative position of the robot with respect to a spherical object fixed in the working area of the robot. The positions of the end effector are related to the incremental positions of resolvers of the robot motors. A kinematic ...

  18. CALIBRATION METHODS FOR NON-METRIC CAMERAS%非量测相机的检校方法

    Institute of Scientific and Technical Information of China (English)

    谢丹; 程效军

    2014-01-01

    非量测相机应用于摄影测量,内部参数是影响其精度的重要因素。分别通过Matlab标定工具箱进行标定、后方交会解算法、透视变换和后方交会交替法等三种方法对相机进行检校,从而获取畸变参数和内方位元素,最后研究了三种方法在不同数量像片条件下的稳定性及精度。结果表明相比于Matlab标定工具箱标定方法,后方交会解算法及透视变换和后方交会交替法检校精度更高,且当三维控制场像片数量少时,后方交会法解算精度更稳定。%Intrinsic parameters are important factors that affect accuracy when non-measured camera is applied to the field of Photogrammetry. We utilize three methods to calibrate a camera for acquiring distortion parameters and elements of interior orientation which are Camera Calibration Toolbox for Matlab, space resection and the alternate calculation of Perspective Transformation and Resection. The conclusion proves that space resection and the alternate calculation of Perspective Transformation and Resection provide higher precision than Camera Calibration Toolbox for Matlab by considering stability and precision of three methods using different amounts of photos. Space resection also provides higher stability when the number of images for three-dimensional control field is scarce.

  19. New method to remove the electronic noise for absolutely calibrating low gain photomultiplier tubes with a higher precision

    Science.gov (United States)

    Zhang, Xiaodong; Hayward, Jason P.; Laubach, Mitchell A.

    2014-08-01

    A new method to remove the electronic noise in order to absolutely calibrate low gain photomultiplier tubes with a higher precision is proposed and validated with experiments using a digitizer-based data acquisition system. This method utilizes the fall time difference between the electronic noise (about 0.5 ns) and the real PMT signal (about 2.4 ns for Hamamatsu H10570 PMT assembly). Using this technique along with a convolution algorithm, the electronic noise and the real signals are separated very well, even including the very small signals heavily influenced by the electronic noise. One application that this method allows is for us to explore the energy relationship for gamma sensing in Cherenkov radiators while maintaining the fastest possible timing performance and high dynamic range.

  20. Residual gas analyzer calibration

    Science.gov (United States)

    Lilienkamp, R. H.

    1972-01-01

    A technique which employs known gas mixtures to calibrate the residual gas analyzer (RGA) is described. The mass spectra from the RGA are recorded for each gas mixture. This mass spectra data and the mixture composition data each form a matrix. From the two matrices the calibration matrix may be computed. The matrix mathematics requires the number of calibration gas mixtures be equal to or greater than the number of gases included in the calibration. This technique was evaluated using a mathematical model of an RGA to generate the mass spectra. This model included shot noise errors in the mass spectra. Errors in the gas concentrations were also included in the valuation. The effects of these errors was studied by varying their magnitudes and comparing the resulting calibrations. Several methods of evaluating an actual calibration are presented. The effects of the number of gases in then, the composition of the calibration mixture, and the number of mixtures used are discussed.

  1. Gray-Tone Lithography Implementation of Drexhage's Method for Calibrating Radiative and Nonradiative Decay Constants of Fluorophores

    CERN Document Server

    Kwadrin, Andrej; 10.1021/jp3048423

    2013-01-01

    We present a straightforward method to realize non-planar dielectric structures with a controlled height profile for use in calibration of fluorophores. Calibration of fluorescence quantum efficiency and intrinsic radiative and nonradiative decay rates of emitters is possible by using changes in the local density of optical states, provided one can control the emitter-surface distance with nanometer accuracy. We realize a method that is accurate yet fast to implement. We fabricate PMMA wedges (4 mm x 4 mm x 2 \\mu m) by gray-tone UV-lithography of Shipley S1813G2. Its applicability as dielectric spacer is demonstrated in Drexhage experiments for three different emitters in the visible and near-infrared wavelength regime. The decay-rate dependence of the fluorescent state of emitters on the distance to a silver mirror is observed and compared to calculations based on the local density of states. Quantitative values for (non)radiative decay rates and quantum efficiencies are extracted. Furthermore, we discuss ho...

  2. An inexpensive method for kinematic calibration of a parallel robot by using one hand-held camera as main sensor.

    Science.gov (United States)

    Traslosheros, Alberto; Sebastián, José María; Torrijos, Jesús; Carelli, Ricardo; Castillo, Eduardo

    2013-01-01

    This paper presents a novel method for the calibration of a parallel robot, which allows a more accurate configuration instead of a configuration based on nominal parameters. It is used, as the main sensor with one camera installed in the robot hand that determines the relative position of the robot with respect to a spherical object fixed in the working area of the robot. The positions of the end effector are related to the incremental positions of resolvers of the robot motors. A kinematic model of the robot is used to find a new group of parameters, which minimizes errors in the kinematic equations. Additionally, properties of the spherical object and intrinsic camera parameters are utilized to model the projection of the object in the image and thereby improve spatial measurements. Finally, several working tests, static and tracking tests are executed in order to verify how the robotic system behaviour improves by using calibrated parameters against nominal parameters. In order to emphasize that, this proposed new method uses neither external nor expensive sensor. That is why new robots are useful in teaching and research activities. PMID:23921827

  3. An Inexpensive Method for Kinematic Calibration of a Parallel Robot by Using One Hand-Held Camera as Main Sensor

    Directory of Open Access Journals (Sweden)

    Ricardo Carelli

    2013-08-01

    Full Text Available This paper presents a novel method for the calibration of a parallel robot, which allows a more accurate configuration instead of a configuration based on nominal parameters. It is used, as the main sensor with one camera installed in the robot hand that determines the relative position of the robot with respect to a spherical object fixed in the working area of the robot. The positions of the end effector are related to the incremental positions of resolvers of the robot motors. A kinematic model of the robot is used to find a new group of parameters, which minimizes errors in the kinematic equations. Additionally, properties of the spherical object and intrinsic camera parameters are utilized to model the projection of the object in the image and thereby improve spatial measurements. Finally, several working tests, static and tracking tests are executed in order to verify how the robotic system behaviour improves by using calibrated parameters against nominal parameters. In order to emphasize that, this proposed new method uses neither external nor expensive sensor. That is why new robots are useful in teaching and research activities.

  4. Numerical design and testing of a sound source for secondary calibration of microphones using the Boundary Element Method

    DEFF Research Database (Denmark)

    Cutanda Henriquez, Vicente; Juhl, Peter Møller; Barrera Figueroa, Salvador

    2009-01-01

    Secondary calibration of microphones in free field is performed by placing the microphone under calibration in an anechoic chamber with a sound source, and exposing it to a controlled sound field. A calibrated microphone is also measured as a reference. While the two measurements are usually made...

  5. Utilización del "dfot heat pulse method" para el estudio del bulbo mojado en goteros

    OpenAIRE

    Gil Rodríguez, María; Rodríguez Sinobas, Leonor; Benitez Buelga, Javier; Sánchez Calvo, Raúl; Juana Sirgado, Luis; Castañon Lion, Guillermo; Laguna Peñuelas, Francisco

    2011-01-01

    Aunque se conocen muchos métodos precisos para medidas de humedad puntuales, hasta hace muy poco, no existían métodos in situ para la medida del contenido de humedad a escala de metros o de kilómetros, importantes cuando pensamos a nivel de cuenca hidrográfica. La fibra óptica ha sido muy utilizada en el área de las comunicaciones. Sin embargo, entre sus aplicaciones más recientes, destaca la de su uso para medir la temperatura incluso en grandes distancias (hasta 10 km) y con una alt...

  6. Counting particles in tissue sections: Choices of methods and importance of calibration to minimize biases

    OpenAIRE

    von Bartheld, C.S.

    2002-01-01

    Investigators must choose between counting methods to quantify microscopic particles in tissues. The c o nventional profile-based ("model-based" or "2D-") counting methods have been criticized for their potential biases due to assumptions about shapes, sizes, and orientation of particles when converting profile counts into cell numbers. New stereological methods ("designbased" or "3D-") methods such as the optical disector or p hysical disector were initially i...

  7. The Laboratory Complex for the Calibration of Photometers Using the Optical Method for Determination of the Water Vapor Content in the Earth Atmosphere

    CERN Document Server

    Galkin, V D; Nikanorova, I N; Leiterer, U; Niebert, T; Alekseeva, G A; Novikov, V V; Ilyin, G N; Pakhomov, V P

    2010-01-01

    We describe the laboratory complex for the calibration of photometers that are used in weather service to measure the water vapor content in the Earth atmosphere. The complex was built up in Pulkovo Observatory and developed within the framework of collaboration between Pulkovo Observatory and Lindenberg Meteorological Observatory (Meteorologisches Observatorium Lindenberg - Richard-A{\\ss}mann-Observatorium, Lindenberg, Germany). It is used to obtain calibration dependences for individual devices, and also to develop and compare various methods of construction of calibration dependences. These techniques are based on direct calibration of the photometers, on the use of spectral laboratory transmission functions for water vapor, on calculation methods using spectroscopical databases for individual lines. We hope that when the parameters of the equipment are taken into account in detail and new results for the absorptive power of water vapor are used, the accuracy of determination of the water vapor content in ...

  8. Influences of finite probe property on soil thermal property estimated by heat pulse technique%探针有限特性对热脉冲技术测定土壤热特性的影响

    Institute of Scientific and Technical Information of China (English)

    付永威; 卢奕丽; 任图生

    2014-01-01

    Soil thermal properties, including volumetric heat capacity, thermal diffusivity, and thermal conductivity, are basic physical parameters for determining the change rate of soil temperature, heat storage and transfer. The heat pulse technique, with the advantages of relative easy operation, minimal soil disturbance, and making repeated and automatic readings, has been used widely for measuring in-situ soil thermal properties. A heat pulse is emitted from a line source enclosed in a stainless heating needle and the temperature rises with time at a shorter distance from the heater are recorded for a few minutes. Soil thermal properties are then estimated from the temperature change by time data. For simplicity, the heat pulse probe is normally considered as a line source with infinitesimal probe radius and zero heat capacity when soil thermal properties are calculated. In reality, the finite properties of the probe itself, including finite heat capacity and finite probe radius, can lead to biased thermal property estimations. In this study, we compared the results of soil thermal property estimations with the PILS (pulsed-infinite-line-source) theory and ICPC (identical cylindrical perfect conductors) theory, to evaluate the influences of finite properties of the probe on soil thermal property estimations. The heat pulse probe consist of 3 needles with a diameter of 2 mm and a length of 40 mm. Heat pulse measurements were conducted on a sand soil with water content varied from air dry condition to field capacity, and soil heat capacity, thermal diffusivity, and thermal conductivity were estimated with both the PILS and ICPC methods. In addition, heat capacity estimates with the de Vries model were used to evaluate the accuracy of heat capacity measurements. The results indicated that compared with the PILS theory, the ICPC solution significantly reduced the errors in soil thermal property estimations from the temperature change-by-time curves. For water content

  9. Method for calibration of asymmetric jaws in hemi fields techniques and effects in clinical practice; Metodo para la calibracion de las mandibulas asimetricas en tecnicas de hemicampos y efectos en la practica clinica

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Masgrau, V.; Sempau Roma, J.; Abella Cereigido, R.; Lopez Sanchez, M.; Perez Fernandez, M.; Gonzalez Leyba, M.; Artigues Pedrola, M.

    2013-07-01

    This paper presents a method improved very significantly the accuracy of calibration, providing a good homogeneity of the dose distribution in the area of union of fields. Also evaluates the effect that has this new calibration in clinical practice. (Author)

  10. A proficiency test system to improve performance of milk analysis methods and produce reference values for component calibration samples for infrared milk analysis.

    Science.gov (United States)

    Wojciechowski, Karen L; Melilli, Caterina; Barbano, David M

    2016-08-01

    Our goal was to determine the feasibility of combining proficiency testing, analytical method quality-assurance system, and production of reference samples for calibration of infrared milk analyzers to achieve a more efficient use of resources and reduce costs while maximizing analytical accuracy within and among milk payment-testing laboratories. To achieve this, we developed and demonstrated a multilaboratory combined proficiency testing and analytical method quality-assurance system as an approach to evaluate and improve the analytical performance of methods. A set of modified milks was developed and optimized to serve multiple purposes (i.e., proficiency testing, quality-assurance and method improvement, and to provide reference materials for calibration of secondary testing methods). Over a period of years, the approach has enabled the group of laboratories to document improved analytical performance (i.e., reduced within- and between-laboratory variation) of chemical reference methods used as the primary reference for calibration of high-speed electronic milk-testing equipment. An annual meeting of the laboratory technicians allows for review of results and discussion of each method and provides a forum for communication of experience and techniques that are of value to new analysts in the group. The monthly proficiency testing sample exchanges have the added benefit of producing all-laboratory mean reference values for a set of 14 milks that can be used for calibration, evaluation, and troubleshooting of calibration adjustment issues on infrared milk analyzers.

  11. A proficiency test system to improve performance of milk analysis methods and produce reference values for component calibration samples for infrared milk analysis.

    Science.gov (United States)

    Wojciechowski, Karen L; Melilli, Caterina; Barbano, David M

    2016-08-01

    Our goal was to determine the feasibility of combining proficiency testing, analytical method quality-assurance system, and production of reference samples for calibration of infrared milk analyzers to achieve a more efficient use of resources and reduce costs while maximizing analytical accuracy within and among milk payment-testing laboratories. To achieve this, we developed and demonstrated a multilaboratory combined proficiency testing and analytical method quality-assurance system as an approach to evaluate and improve the analytical performance of methods. A set of modified milks was developed and optimized to serve multiple purposes (i.e., proficiency testing, quality-assurance and method improvement, and to provide reference materials for calibration of secondary testing methods). Over a period of years, the approach has enabled the group of laboratories to document improved analytical performance (i.e., reduced within- and between-laboratory variation) of chemical reference methods used as the primary reference for calibration of high-speed electronic milk-testing equipment. An annual meeting of the laboratory technicians allows for review of results and discussion of each method and provides a forum for communication of experience and techniques that are of value to new analysts in the group. The monthly proficiency testing sample exchanges have the added benefit of producing all-laboratory mean reference values for a set of 14 milks that can be used for calibration, evaluation, and troubleshooting of calibration adjustment issues on infrared milk analyzers. PMID:27209129

  12. An Investigation of a Novel Cross-Calibration Method of FY-3C/VIRR against NPP/VIIRS in the Dunhuang Test Site

    Directory of Open Access Journals (Sweden)

    Caixia Gao

    2016-01-01

    Full Text Available Radiometric cross-calibration of Earth observation sensors is an effective approach to evaluate instrument calibration performance, identify and diagnose calibration anomalies, and quantify the consistency of measurements from different sensors. In this study a novel cross-calibration method is proposed, taking into account the spectral and viewing angle differences adequately; the method is applied to the FY-3C/Visible Infrared Radiometer (VIRR, taking the Suomi National Polar-Orbiting Partnership (NPP/Visible Infrared Imaging Radiometer Suite (VIIRS as a reference. The results show that the relative difference between the two sets increases from January to May 2014, and becomes lower for the data on 24 July, 11 September, and 16 September, within approximately 10%. This phenomenon is caused by the updating of the calibration coefficients in the VIRR datasets with results from a vicarious method on June 2014. After performing an approximate estimation of the uncertainty, it is demonstrated that this calibration has a total uncertainty of 5.5%–6.0%, which is mainly from the uncertainty of the Bidirectional Reflectance Distribution Function model.

  13. Rotated-Random-Scanning: a simple method for set-valued model calibration

    NARCIS (Netherlands)

    Janssen PHM; Heuberger PSC; CWM

    1995-01-01

    Een eenvoudige methode wordt voorgesteld voor het kalibreren van modellen in slecht-gedefinieerde en informatie-arme situaties, die veelvuldig worden aangetroffen bij milieu-onderzoek. De methode volvoert een efficiente zoekaktie in de parameterruimte op basis van Monte Carlo trekkingen in combi

  14. Field calibration of cup anemometers

    DEFF Research Database (Denmark)

    Schmidt Paulsen, Uwe; Mortensen, Niels Gylling; Hansen, Jens Carsten;

    2007-01-01

    A field calibration method and results are described along with the experience gained with the method. The cup anemometers to be calibrated are mounted in a row on a 10-m high rig and calibrated in the free wind against a reference cup anemometer. The method has been reported [1] to improve the...... statistical bias on the data relative to calibrations carried out in a wind tunnel. The methodology is sufficiently accurate for calibration of cup anemometers used for wind resource assessments and provides a simple, reliable and cost-effective solution to cup anemometer calibration, especially suited for...

  15. Calibration of UV/Vis spectrophotometers: A review and comparison of different methods to estimate TSS and total and dissolved COD concentrations in sewers, WWTPs and rivers.

    Science.gov (United States)

    Lepot, Mathieu; Torres, Andres; Hofer, Thomas; Caradot, Nicolas; Gruber, Günter; Aubin, Jean-Baptiste; Bertrand-Krajewski, Jean-Luc

    2016-09-15

    UV/Vis spectrophotometers have been used for one decade to monitor water quality in various locations: sewers, rivers, wastewater treatment plants (WWTPs), tap water networks, etc. Resulting equivalent concentrations of interest can be estimated by three ways: i) by manufacturer global calibration; ii) by local calibration based on the provided global calibration and grab sampling; iii) by advanced calibration looking for relations between UV/Vis spectra and corresponding concentrations from grab sampling. However, no study has compared the applied methods so far. This collaborative work presents a comparison between five different methods. A Linear Regression (LR), Support Vector Machine (SVM), EVOlutionary algorithm method (EVO) and Partial Least Squares (PLS) have been applied on various data sets (sewers, rivers, WWTPs under dry, wet and all weather conditions) and for three water quality parameters: TSS, COD total and dissolved. Two criteria (r(2) and Root Mean Square Error RMSE) have been calculated - on calibration and verification data subsets - to evaluate accuracy and robustness of the applied methods. Values of criteria have then been statistically analysed for all and separated data sets. Non-consistent outcomes come through this study. According to the Kruskal-Wallis test and RMSEs, PLS and SVM seem to be the best methods. According to uncertainties in laboratory analysis and ranking of methods, LR and EVO appear more robust and sustainable for concentration estimations. Conclusions are mostly independent of water matrices, weather conditions or concentrations investigated. PMID:27295626

  16. Polarimetric calibration of large mirrors

    CERN Document Server

    Ariste, A Lopez

    2015-01-01

    Aims: To propose a method for the polarimetric calibration of large astronomical mirrors that does not require use of special optical devices nor knowledge of the exact polarization properties of the calibration target. Methods: We study the symmetries of the Mueller matrix of mirrors to exploit them for polarimetric calibration under the assumptions that only the orientation of the linear polarization plane of the calibration target is known with certainty. Results: A method is proposed to calibrate the polarization effects of single astronomical mirrors by the observation of calibration targets with known orientation of the linear polarization. We study the uncertainties of the method and the signal-to-noise ratios required for an acceptable calibration. We list astronomical targets ready for the method. We finally extend the method to the calibration of two or more mirrors, in particular to the case when they share the same incidence plane.

  17. Calibration of a gamma spectrometer for measuring natural radioactivity. Experimental measurements and modeling by Monte-Carlo methods

    International Nuclear Information System (INIS)

    The thesis proceeded in the context of dating by thermoluminescence. This method requires laboratory measurements of the natural radioactivity. For that purpose, we have been using a germanium spectrometer. To refine the calibration of this one, we modelled it by using a Monte-Carlo computer code: Geant4. We developed a geometrical model which takes into account the presence of inactive zones and zones of poor charge-collection within the germanium crystal. The parameters of the model were adjusted by comparison with experimental results obtained with a source of 137Cs. It appeared that the form of the inactive zones is less simple than is presented in the specialized literature. This model was widened to the case of a more complex source, with cascade effect and angular correlations between photons: the 60Co. Lastly, applied to extended sources, it gave correct results and allowed us to validate the simulation of matrix effect. (author)

  18. A Bayesian Calibration-Prediction Method for Reducing Model-Form Uncertainties with Application in RANS Simulations

    CERN Document Server

    Wu, J -L; Xiao, H

    2015-01-01

    Model-form uncertainties in complex mechanics systems are a major obstacle for predictive simulations. Reducing these uncertainties is critical for stake-holders to make risk-informed decisions based on numerical simulations. For example, Reynolds-Averaged Navier-Stokes (RANS) simulations are increasingly used in mission-critical systems involving turbulent flows. However, for many practical flows the RANS predictions have large model-form uncertainties originating from the uncertainty in the modeled Reynolds stresses. Recently, a physics-informed Bayesian framework has been proposed to quantify and reduce model-form uncertainties in RANS simulations by utilizing sparse observation data. However, in the design stage of engineering systems, measurement data are usually not available. In the present work we extend the original framework to scenarios where there are no available data on the flow to be predicted. In the proposed method, we first calibrate the model discrepancy on a related flow with available dat...

  19. Determination of Propranolol Hydrochloride in Pharmaceutical Preparations Using Near Infrared Spectrometry with Fiber Optic Probe and Multivariate Calibration Methods

    Directory of Open Access Journals (Sweden)

    Jucelino Medeiros Marques Junior

    2015-01-01

    Full Text Available A method for determination of propranolol hydrochloride in pharmaceutical preparation using near infrared spectrometry with fiber optic probe (FTNIR/PROBE and combined with chemometric methods was developed. Calibration models were developed using two variable selection models: interval partial least squares (iPLS and synergy interval partial least squares (siPLS. The treatments based on the mean centered data and multiplicative scatter correction (MSC were selected for models construction. A root mean square error of prediction (RMSEP of 8.2 mg g−1 was achieved using siPLS (s2i20PLS algorithm with spectra divided into 20 intervals and combination of 2 intervals (8501 to 8801 and 5201 to 5501 cm−1. Results obtained by the proposed method were compared with those using the pharmacopoeia reference method and significant difference was not observed. Therefore, proposed method allowed a fast, precise, and accurate determination of propranolol hydrochloride in pharmaceutical preparations. Furthermore, it is possible to carry out on-line analysis of this active principle in pharmaceutical formulations with use of fiber optic probe.

  20. Methods of measurement and calibration in personnel dosimetry for external irradiation: presentation of the concept and the results of a test programme in Switzerland

    International Nuclear Information System (INIS)

    In 1986 the Swiss working group on personnel dosimetry issued a recommendation on methods of calibration and measurement in personnel dosimetry for external radiation, based on ICRU report 39. The aim of the report was to give detailed and pragmatic guidance to the dosimetry services and the calibration labs. In the recommendation a definition is given for primary and secondary limited quantities, for calibration quantities and operational quantities as well as for their interrelationships. The second part of the report is a manual for the calibration and evaluation procedures for whole-body and extremity dosemeters for photon and electron radiation. Based on that recommendation an extended test programme has been performed for all dosimetry services in Switzerland. The results show that the legal introduction of the recommended concept has no severe consequences for the dosimetry services although a number of minor modifications are needed. (author)

  1. Estimation of the measurement uncertainty in quantitative determination of ketamine and norketamine in urine using a one-point calibration method.

    Science.gov (United States)

    Ma, Yi-Chun; Wang, Che-Wei; Hung, Sih-Hua; Chang, Yan-Zin; Liu, Chia-Reiy; Her, Guor-Rong

    2012-09-01

    An approach was proposed for the estimation of measurement uncertainty for analytical methods based on one-point calibration. The proposed approach is similar to the popular multiple-point calibration approach. However, the standard deviation of calibration was estimated externally. The approach was applied to the estimation of measurement uncertainty for the quantitative determination of ketamine (K) and norketamine (NK) at a 100 ng/mL threshold concentration in urine. In addition to uncertainty due to calibration, sample analysis was the other major source of uncertainty. To include the variation due to matrix effect and temporal effect in sample analysis, different blank urines were spiked with K and NK and analyzed at equal time intervals within and between batches. The expanded uncertainties (k = 2) were estimated to be 10 and 8 ng/mL for K and NK, respectively.

  2. Implementation of the method air-kerma product area in KAP camera calibration with reference qualities of X-ray series at the SSDL RQR of Mexico

    International Nuclear Information System (INIS)

    The X-Ray machines, at a reference laboratory for the instrument calibration in diagnostic radiology, should compliance with the ISO requirements. Sometimes there is not available as much laboratories as needed in Latin American countries. So this project shows the KAP ionization chamber implementation method using the TRS-457 radiation quality from the IAEA at the SSDL of Mexico. The KAP instruments calibration method consists in doing a substitution comparison using a standard reference with traceability to a primary laboratory and a transmission-monitoring chamber that measures the number of photons of the X-ray primary beam. A KAP chamber calibration requires a special array that consists in collocating the chamber in two different positions of its calibration process. Then, with air kerma-area product coefficient together with a corrected electrometer measure at referential conditions, the patient dosimetry magnitudes are calculated. The dosimetry necessity at hospitals always will be in function of possessing a highly reliable calibration coefficient chamber for making these measures. That dosimetry results will help in reducing the total or partial irradiation emitted to the human body of the patient. This is how stochastic risks will be lessened due to diagnostic studies. The purpose of this project is to have a synergy with calibration for making known that the SSDL of Mexico has the technical capacity to act as a link between primary standard dosimetry laboratories and the ionizing radiation equipment users who require that their KAP chamber have traceability from the primary standard to the user. (author)

  3. Accuracy of the FT-NIR Method in Evaluating the Fat Content of Milk Using Calibration Models Developed for the Reference Methods According to Röse-Gottlieb and Gerber.

    Science.gov (United States)

    Mlcek, Jiri; Dvorak, Lukas; Sustova, Kvetoslava; Szwedziak, Katarzyna

    2016-09-01

    The study examined the effect of the choice of reference method on the functionality and reliability of calibrations in near-IR (NIR) spectroscopy intended for measuring the fat content in raw cow's milk. The fat content in the milk samples was evaluated using methods according to either Röse-Gottlieb or Gerber. The same samples were then subjected to analysis on an Antaris FT-NIR spectrometer. Using a partial least-squares algorithm, calibration models were created for both methods from the values measured. The calibration models show very good values of standard error of calibration: 0.133 for the Gerber method and 0.095 for the Röse-Gottlieb method. These calibrations were subsequently used to analyze 30 new samples of cow's milk of undefined fat content, and the differences in the values were evaluated using statistical paired t-test to a median value at a probability level of α = 0.05. No statistically significant differences were found. It was revealed that the reference method used for calibrating the device evaluating the fat content in raw cow's milk has no effect on the functionality and reliability of the calibration model.

  4. Multi Function Heat Pulse Probes (MFHPP) to Estimate Ground Heat Flux and Reduce Surface Energy Budget Errors

    Science.gov (United States)

    Ciocca, Francesco; Sharma, Varun; Lunati, Ivan; Parlange, Marc B.

    2013-04-01

    Ground heat flux plays a crucial role in surface energy budget: an incorrect estimation of energy storage and heat fluxes in soils occur when probes such as heat flux plates are adopted, and these mistakes can account for up to 90% of the residual variance (Higgins, GRL, 2012). A promising alternative to heat flux plates is represented by Multi Function Heat Pulse Probes (MFHPP). They have proven to be accurate in thermal properties and heat fluxes estimation (e.g. Cobos, VZJ, 2003) and can be used to monitor and quantify subsurface evaporation in field experiments (Xiao et al., VZJ, 2011). We perform a laboratory experiment with controlled temperature in a small Plexiglas column (20cm diameter and 40cm height). The column is packed with homogeneously saturated sandy soil and equipped with three MFHPPs in the upper 4cm and thermocouples and dielectric soil moisture probes deeper. This configuration allows for accurate and simultaneous ground heat flux, soil moisture and subsurface evaporation measurements. Total evaporation is monitored using a precision scale, while an infrared gun and a long wave radiometer measure the soil skin temperature and the outgoing long-short wave radiation, respectively. A fan and a heat lamp placed above the column allow to mimick on a smaller and more controlled scale the field conditions induced by the diurnal cycle. At a reference height above the column relative humidity, wind speed and air temperature are collected. Results are interpreted by means of numerical simulations performed with an ad-hoc-developed numerical model that simulates coupled heat and moisture transfer in soils and is used to match and interpolate the temperature and soil moisture values got at finite depths within the column. Ground heat fluxes are then estimated by integrating over almost continuous, numerically simulated temperature profiles, which avoids errors due to use of discrete data (Lunati et al., WRR, 2012) and leads to a more reliable estimate of

  5. An improved calibration method for the drift of the conductivity sensor on autonomous CTD profiling floats by θ- S climatology

    Science.gov (United States)

    Owens, W. Brechner; Wong, Annie P. S.

    2009-03-01

    An improved method to estimate the time-varying drift of measured conductivity from autonomous CTD profiling floats has been developed. This procedure extends previous methods developed by Wong, Johnson and Owens [2003. Delayed-mode calibration of autonomous CTD profiling float salinity data by θ- S climatology. Journal of Atmospheric and Oceanic Technology, 20, 308-318] and Böhme and Send [2005. Objective analyses of hydrographic data for referencing profiling float salinities in highly variable environments. Deep-Sea Research Part II, 52, 651-664]. It uses climatological salinity interpolated to the float positions and observed θ surfaces and chooses 10 'best' levels that are within well-mixed mode waters or deep homogeneous water masses. A piece-wise linear fit is used to estimate the temporally varying multiplicative adjustment to the float potential conductivities. An objective, statistical method is used to choose the breakpoints in the float time series where there are multiple drift trends. In the previous methods these breakpoints were chosen subjectively by manually splitting the time series into separate segments over which the fits were made. Our statistical procedure reduces the subjectivity by providing an automated way for doing the piece-wise linear fit. Uncertainties in this predicted adjustment are estimated using a Monte-Carlo simulation. Examples of this new procedure as applied to two Argo floats are presented.

  6. Z-correction, a method for achieving ultraprecise self-calibration on large area coordinate measurement machines for photomasks

    Science.gov (United States)

    Ekberg, Peter; Stiblert, Lars; Mattsson, Lars

    2014-05-01

    High-quality photomasks are a prerequisite for the production of flat panel TVs, tablets and other kinds of high-resolution displays. During the past years, the resolution demand has become more and more accelerated, and today, the high-definition standard HD, 1920 × 1080 pixels2, is well established, and already the next-generation so-called ultra-high-definition UHD or 4K display is entering the market. Highly advanced mask writers are used to produce the photomasks needed for the production of such displays. The dimensional tolerance in X and Y on absolute pattern placement on these photomasks, with sizes of square meters, has been in the range of 200-300 nm (3σ), but is now on the way to be <150 nm (3σ). To verify these photomasks, 2D ultra-precision coordinate measurement machines are used with even tighter tolerance requirements. The metrology tool MMS15000 is today the world standard tool used for the verification of large area photomasks. This paper will present a method called Z-correction that has been developed for the purpose of improving the absolute X, Y placement accuracy of features on the photomask in the writing process. However, Z-correction is also a prerequisite for achieving X and Y uncertainty levels <90 nm (3σ) in the self-calibration process of the MMS15000 stage area of 1.4 × 1.5 m2. When talking of uncertainty specifications below 200 nm (3σ) of such a large area, the calibration object used, here an 8-16 mm thick quartz plate of size approximately a square meter, cannot be treated as a rigid body. The reason for this is that the absolute shape of the plate will be affected by gravity and will therefore not be the same at different places on the measurement machine stage when it is used in the self-calibration process. This mechanical deformation will stretch or compress the top surface (i.e. the image side) of the plate where the pattern resides, and therefore spatially deform the mask pattern in the X- and Y-directions. Errors due

  7. Z-correction, a method for achieving ultraprecise self-calibration on large area coordinate measurement machines for photomasks

    International Nuclear Information System (INIS)

    High-quality photomasks are a prerequisite for the production of flat panel TVs, tablets and other kinds of high-resolution displays. During the past years, the resolution demand has become more and more accelerated, and today, the high-definition standard HD, 1920 × 1080 pixels2, is well established, and already the next-generation so-called ultra-high-definition UHD or 4K display is entering the market. Highly advanced mask writers are used to produce the photomasks needed for the production of such displays. The dimensional tolerance in X and Y on absolute pattern placement on these photomasks, with sizes of square meters, has been in the range of 200–300 nm (3σ), but is now on the way to be <150 nm (3σ). To verify these photomasks, 2D ultra-precision coordinate measurement machines are used with even tighter tolerance requirements. The metrology tool MMS15000 is today the world standard tool used for the verification of large area photomasks. This paper will present a method called Z-correction that has been developed for the purpose of improving the absolute X, Y placement accuracy of features on the photomask in the writing process. However, Z-correction is also a prerequisite for achieving X and Y uncertainty levels <90 nm (3σ) in the self-calibration process of the MMS15000 stage area of 1.4 × 1.5 m2. When talking of uncertainty specifications below 200 nm (3σ) of such a large area, the calibration object used, here an 8–16 mm thick quartz plate of size approximately a square meter, cannot be treated as a rigid body. The reason for this is that the absolute shape of the plate will be affected by gravity and will therefore not be the same at different places on the measurement machine stage when it is used in the self-calibration process. This mechanical deformation will stretch or compress the top surface (i.e. the image side) of the plate where the pattern resides, and therefore spatially deform the mask pattern in the X- and Y

  8. Flight Test Results of a GPS-Based Pitot-Static Calibration Method Using Output-Error Optimization for a Light Twin-Engine Airplane

    Science.gov (United States)

    Martos, Borja; Kiszely, Paul; Foster, John V.

    2011-01-01

    As part of the NASA Aviation Safety Program (AvSP), a novel pitot-static calibration method was developed to allow rapid in-flight calibration for subscale aircraft while flying within confined test areas. This approach uses Global Positioning System (GPS) technology coupled with modern system identification methods that rapidly computes optimal pressure error models over a range of airspeed with defined confidence bounds. This method has been demonstrated in subscale flight tests and has shown small 2- error bounds with significant reduction in test time compared to other methods. The current research was motivated by the desire to further evaluate and develop this method for full-scale aircraft. A goal of this research was to develop an accurate calibration method that enables reductions in test equipment and flight time, thus reducing costs. The approach involved analysis of data acquisition requirements, development of efficient flight patterns, and analysis of pressure error models based on system identification methods. Flight tests were conducted at The University of Tennessee Space Institute (UTSI) utilizing an instrumented Piper Navajo research aircraft. In addition, the UTSI engineering flight simulator was used to investigate test maneuver requirements and handling qualities issues associated with this technique. This paper provides a summary of piloted simulation and flight test results that illustrates the performance and capabilities of the NASA calibration method. Discussion of maneuver requirements and data analysis methods is included as well as recommendations for piloting technique.

  9. A spectral synthesis method to suppress aliasing and calibrate for delay errors in Fourier transform correlators

    CERN Document Server

    Kaneko, Tak

    2008-01-01

    Context: Fourier transform (or lag) correlators in radio interferometers can serve as an efficient means of synthesising spectral channels. However aliasing corrupts the edge channels so they usually have to be excluded from the data set. In systems with around 10 channels, the loss in sensitivity can be significant. In addition, the low level of residual aliasing in the remaining channels may cause systematic errors. Moreover, delay errors have been widely reported in implementations of broadband analogue correlators and simulations have shown that delay errors exasperate the effects of aliasing. Aims: We describe a software-based approach that suppresses aliasing by oversampling the cross-correlation function. This method can be applied to interferometers with individually-tracking antennas equipped with a discrete path compensator system. It is based on the well-known property of interferometers where the drift scan response is the Fourier transform of the source's band-limited spectrum. Methods: In this p...

  10. Calibration and Measurement in Turbulence Research by the Hot-Wire Method

    Science.gov (United States)

    Kovasznay, Kaszlo

    1947-01-01

    The problem of turbulence in aerodynamics is at present being attacked both theoretically and experimentally. In view of the fact however that purely theoretical considerations have not thus far led to satisfactory results the experimental treatment of the problem is of great importance. Among the different measuring procedures the hot wire methods are so far recognized as the most suitable for investigating the turbulence structure. The several disadvantages of these methods however, in particular those arising from the temperature lag of the wire can greatly impair the measurements and may easily render questionable the entire value of the experiment. The name turbulence is applied to that flow condition in which at any point of the stream the magnitude and direction of the velocity fluctuate arbitrarily about a well definable mean value. This fluctuation imparts a certain whirling characteristic to the flow.

  11. Correction of interstitial water changes in calibration methods applied to XRF core-scanning major elements in long sediment cores: Case study from the South China Sea

    Science.gov (United States)

    Chen, Quan; Kissel, Catherine; Govin, Aline; Liu, Zhifei; Xie, Xin

    2016-05-01

    Fast and nondestructive X-ray fluorescence (XRF) core scanning provides high-resolution element data that are widely used in paleoclimate studies. However, various matrix and specimen effects prevent the use of semiquantitative raw XRF core-scanning intensities for robust paleoenvironmental interpretations. We present here a case study of a 50.8 m-long piston Core MD12-3432 retrieved from the northern South China Sea. The absorption effect of interstitial water is identified as the major source of deviations between XRF core-scanning intensities and measured element concentrations. The existing two calibration methods, i.e., normalized median-scaled calibration (NMS) and multivariate log-ratio calibration (MLC), are tested with this sequence after the application of water absorption correction. The results indicate that an improvement is still required to appropriately correct the influence of downcore changes in interstitial water content in the long sediment core. Consequently, we implement a new polynomial water content correction in NMS and MLC methods, referred as NPS and P_MLC calibrations. Results calibrated by these two improved methods indicate that the influence of downcore water content changes is now appropriately corrected. We therefore recommend either of the two methods to be applied for robust paleoenvironmental interpretations of major elements measured by XRF-scanning in long sediment sequences with significant downcore interstitial water content changes.

  12. 最小二乘法分段拟合标定反应谱方法%Sectional least square fitting method for calibrating seismic design response spectrum

    Institute of Scientific and Technical Information of China (English)

    郭晓云; 薄景山; 巴文辉; 田启文; 李平

    2012-01-01

    The method of calibrating seismic design response spectrum is related directly to the determination of the characteristic parameters of response spectrum, and seismic design response spectrum based on logical calibrating method can express the real characteristic of earthquake strong motion. So calibration of seismic design response spectrum is the important chain of structures' seismic input determination. This paper advances least square fitting method of calibrating seismic design response spectrum based on coordinate transformation. By calculating the characteristic parameters of typical Wenchuan earthquake strong motion records and comparing different calibrating methods and analyzing the error of different methods, it points out that sectional least square fitting method is a simple and reasonable calibrating method.%反应谱的标定方法直接关系到反应谱特征参数的确定,合理的反应谱标定方法得到的设计反应谱能够真实地表达地震动的特性,是确定地震动输入的重要环节.提出了基于坐标变换的最小二乘法分段拟合方法,通过对汶川大地震不同场地典型强震记录反应谱的标定,对比了反应谱不同的标定方法,根据反应谱标定图形的对比及误差分析认为,最小二乘法分段拟合方法是操作简便且标定结果合理的反应谱标定方法.

  13. Standardisation of data from real-time quantitative PCR methods – evaluation of outliers and comparison of calibration curves

    Directory of Open Access Journals (Sweden)

    Burns Malcolm J

    2005-12-01

    Full Text Available Abstract Background As real-time quantitative PCR (RT-QPCR is increasingly being relied upon for the enforcement of legislation and regulations dependent upon the trace detection of DNA, focus has increased on the quality issues related to the technique. Recent work has focused on the identification of factors that contribute towards significant measurement uncertainty in the real-time quantitative PCR technique, through investigation of the experimental design and operating procedure. However, measurement uncertainty contributions made during the data analysis procedure have not been studied in detail. This paper presents two additional approaches for standardising data analysis through the novel application of statistical methods to RT-QPCR, in order to minimise potential uncertainty in results. Results Experimental data was generated in order to develop the two aspects of data handling and analysis that can contribute towards measurement uncertainty in results. This paper describes preliminary aspects in standardising data through the application of statistical techniques to the area of RT-QPCR. The first aspect concerns the statistical identification and subsequent handling of outlying values arising from RT-QPCR, and discusses the implementation of ISO guidelines in relation to acceptance or rejection of outlying values. The second aspect relates to the development of an objective statistical test for the comparison of calibration curves. Conclusion The preliminary statistical tests for outlying values and comparisons between calibration curves can be applied using basic functions found in standard spreadsheet software. These two aspects emphasise that the comparability of results arising from RT-QPCR needs further refinement and development at the data-handling phase. The implementation of standardised approaches to data analysis should further help minimise variation due to subjective judgements. The aspects described in this paper will

  14. Calibration and validation of ultrasonic reflection methods for thin-film measurement in tribology

    International Nuclear Information System (INIS)

    Interfacial thin liquid films between solid bodies have been measured using ultrasonic reflective techniques in a range of tribological applications such as those present in hydrodynamic bearings, piston rings and mechanical seals (Dwyer-Joyce et al (2004) Tribol. Lett. 17 337–48, Dwyer-Joyce et al (2006) Proc. Instn Mech. Eng. A 220 619–28, Reddyhoff et al (2006) Tribol. Trans. 51 140–49, Harper et al (2005) Tribol. Interface Eng. Ser. 48 305–12). There are two main ultrasonic methods used, the spring model and film resonance techniques. For very thin films (<20 µm) a simple quasi-static spring model has been used to show that the proportion of the wave reflected by the liquid layer depends on the stiffness of the layer. This stiffness can be related to the layer thickness and its material properties. In the film resonance technique the incident ultrasonic wave is used to resonate the liquid layer. The frequency of resonance can then be related to the layer thickness. This paper collates four experiments where oil film thickness is measured by both ultrasonic reflection and an independent method. In the first three experiments the film thickness is measured ultrasonically and this measurement is compared to the thickness inferred from the geometry of the surfaces constraining the liquid film. In the final experiment the ultrasonic results are compared to measurements taken using capacitive and verified laser interferometer techniques. Excellent correlation was observed between the measurement methods in all of the experiments. In particular the film resonance technique showed repeatable and consistent results across a wide range of film thicknesses. The spring model showed a degree of agreement for films above a few microns but this relationship diverged as the film thickness approached the magnitude of the surface roughness. (paper)

  15. Pleiades Absolute Calibration : Inflight Calibration Sites and Methodology

    Science.gov (United States)

    Lachérade, S.; Fourest, S.; Gamet, P.; Lebègue, L.

    2012-07-01

    In-flight calibration of space sensors once in orbit is a decisive step to be able to fulfil the mission objectives. This article presents the methods of the in-flight absolute calibration processed during the commissioning phase. Four In-flight calibration methods are used: absolute calibration, cross-calibration with reference sensors such as PARASOL or MERIS, multi-temporal monitoring and inter-bands calibration. These algorithms are based on acquisitions over natural targets such as African deserts, Antarctic sites, La Crau (Automatic calibration station) and Oceans (Calibration over molecular scattering) or also new extra-terrestrial sites such as the Moon and selected stars. After an overview of the instrument and a description of the calibration sites, it is pointed out how each method is able to address one or several aspects of the calibration. We focus on how these methods complete each other in their operational use, and how they help building a coherent set of information that addresses all aspects of in-orbit calibration. Finally, we present the perspectives that the high level of agility of PLEIADES offers for the improvement of its calibration and a better characterization of the calibration sites.

  16. The Experiment and Simulation Method to Calibrate the Shear Modulus of Individual ZnO Nanorod.

    Science.gov (United States)

    Yu, Guangbin; Jiang, Chengming; Dai, Bing; Song, Jinhui

    2016-04-01

    A general method is presented to directly measure the shear modulus of an individual nanorod using atomic force microscope (AFM). To obtain shear modulus with less experiment error, finite element simulation is employed to simulate the twisting process of a ZnO nanorod. Based on the experimental measurements, the shear modulus of ZnO nanorod with 4 µm in length and 166 nm in radius is characterized to be 9.1 ± 0.2 GPa, which is obviously more accurate than the simple averaged experimental result. PMID:27451763

  17. Stellar color regression: a spectroscopy based method for color calibration to a few mmag accuracy and the recalibration of Stripe 82

    CERN Document Server

    Yuan, Haibo; Xiang, Maosheng; Huang, Yang; Zhang, Huihua; Chen, Bingqiu

    2014-01-01

    In this paper, we propose a spectroscopy based Stellar Color Regression (SCR) method to perform accurate color calibration for modern imaging surveys, taking advantage of millions of stellar spectra now available. The method is straightforward, insensitive to systematic errors in the spectroscopically determined stellar atmospheric parameters, applicable to regions that are effectively covered by spectroscopic surveys, and capable of delivering an accuracy of a few millimagnitudes for color calibration. As an illustration, we have applied the method to the SDSS Stripe 82 data (Ivezic et al; I07 hereafter). With a total number of 23,759 spectroscopically targeted stars, we have mapped out the small but strongly correlated color zero point errors present in the photometric catalog of Stripe 82, and improve the color calibration by a factor of 2 -- 3. Our study also reveals some small but significant magnitude dependence errors in z-band for some CCDs. Such errors are likely to be present in all the SDSS photome...

  18. Multivariate versus classical univariate calibration methods for spectrofluorimetric data: application to simultaneous determination of olmesartan medoxamil and amlodipine besylate in their combined dosage form.

    Science.gov (United States)

    Darwish, Hany W; Backeit, Ahmed H

    2013-01-01

    Olmesartan medoxamil (OLM, an angiotensin II receptor blocker) and amlodipine besylate (AML, a dihydropyridine calcium channel blocker), are co-formulated in a single-dose combination for the treatment of hypertensive patients whose blood pressure is not adequately controlled on either component monotherapy. In this work, four multivariate and two univariate calibration methods were applied for simultaneous spectrofluorimetric determination of OLM and AML in their combined pharmaceutical tablets in all ratios approved by FDA. The four multivariate methods are partial least squares (PLS), genetic algorithm PLS (GA-PLS), principal component ANN (PC-ANN) and GA-ANN. The two proposed univariate calibration methods are, direct spectrofluorimetric method for OLM and isoabsorpitive method for determination of total concentration of OLM and AML and hence AML by subtraction. The results showed the superiority of multivariate calibration methods over univariate ones for the analysis of the binary mixture. The optimum assay conditions were established and the proposed multivariate calibration methods were successfully applied for the assay of the two drugs in validation set and combined pharmaceutical tablets with excellent recoveries. No interference was observed from common pharmaceutical additives. The results were favorably compared with those obtained by a reference spectrophotometric method. PMID:22895851

  19. 一种螺栓拉伸器校准方法研究%A Calibration Method Research for Bolt Tensioners

    Institute of Scientific and Technical Information of China (English)

    赵兴亮; 杨思凡; 李玮; 陈宝有

    2015-01-01

    A calibration method for bolt tensioners is presented. According to the theory of Newton's Third Law, the calibration device is researched and designed to calibrate the bolt tensioners. The meas-urement error and repeatability analysis and uncertainty evaluation show the linearity is good. Considering the measurement error is within ±1%, which meets the calibration requirements for bolt tensioners, the designed calibration device is capable to carry out the calibration work for bolt tensioners.%介绍了螺栓拉伸器的一种校准方法,运用牛顿第三定律的基本原理,研究并设计了一种拉伸器校准装置对螺栓拉伸器进行校准,通过对实验结果的误差和重复性分析,以及不确定度评定,表明该拉伸器校准装置具有良好的线性度,测量误差在±1%以内,符合螺栓拉伸器校准要求,达到了校准螺栓拉伸器的目的,可以开展螺栓拉伸器校准工作。

  20. Developing a method for soft gamma-ray Laue lens assembly and calibration

    CERN Document Server

    Barrière, Nicolas M; Boggs, Steven E; Lowell, Alexander; Wade, Colin; Baugh, Max; von Ballmoos, Peter; Abrosimov, Nikolay V; Hanlon, Lorraine

    2013-01-01

    Laue lenses constitute a promising option for concentrating soft gamma rays with a large collection area and reasonable focal lengths. In astronomy they could lead to increased telescope sensitivity by one to two orders of magnitude, in particular for faint nuclear gamma-ray lines, but also for continua like hard X-ray tails from a variety of compact objects. Other fields like Homeland security and nuclear medicine share the same need for more sensitive gamma-ray detection systems and could find applications for gamma-ray focusing optics. There are two primary challenges for developing Laue lenses: the search for high-reflectivity and reproducible crystals, and the development of a method to accurately orient and fix the thousands of crystals constituting a lens. In this paper we focus on the second topic. We used our dedicated X-ray beamline and Laue lens assembly station to build a breadboard lens made of 15 crystals. This allowed us to test our tools and methods, as well as our simulation code and calibrat...

  1. Boosting iterative stochastic ensemble method for nonlinear calibration of subsurface flow models

    KAUST Repository

    Elsheikh, Ahmed H.

    2013-06-01

    A novel parameter estimation algorithm is proposed. The inverse problem is formulated as a sequential data integration problem in which Gaussian process regression (GPR) is used to integrate the prior knowledge (static data). The search space is further parameterized using Karhunen-Loève expansion to build a set of basis functions that spans the search space. Optimal weights of the reduced basis functions are estimated by an iterative stochastic ensemble method (ISEM). ISEM employs directional derivatives within a Gauss-Newton iteration for efficient gradient estimation. The resulting update equation relies on the inverse of the output covariance matrix which is rank deficient.In the proposed algorithm we use an iterative regularization based on the ℓ2 Boosting algorithm. ℓ2 Boosting iteratively fits the residual and the amount of regularization is controlled by the number of iterations. A termination criteria based on Akaike information criterion (AIC) is utilized. This regularization method is very attractive in terms of performance and simplicity of implementation. The proposed algorithm combining ISEM and ℓ2 Boosting is evaluated on several nonlinear subsurface flow parameter estimation problems. The efficiency of the proposed algorithm is demonstrated by the small size of utilized ensembles and in terms of error convergence rates. © 2013 Elsevier B.V.

  2. Mean-free-paths in concert and chamber music halls and the correct method for calibrating dodecahedral sound sources.

    Science.gov (United States)

    Beranek, Leo L; Nishihara, Noriko

    2014-01-01

    The Eyring/Sabine equations assume that in a large irregular room a sound wave travels in straight lines from one surface to another, that the surfaces have an average sound absorption coefficient αav, and that the mean-free-path between reflections is 4 V/Stot where V is the volume of the room and Stot is the total area of all of its surfaces. No account is taken of diffusivity of the surfaces. The 4 V/Stot relation was originally based on experimental determinations made by Knudsen (Architectural Acoustics, 1932, pp. 132-141). This paper sets out to test the 4 V/Stot relation experimentally for a wide variety of unoccupied concert and chamber music halls with seating capacities from 200 to 5000, using the measured sound strengths Gmid and reverberation times RT60,mid. Computer simulations of the sound fields for nine of these rooms (of varying shapes) were also made to determine the mean-free-paths by that method. The study shows that 4 V/Stot is an acceptable relation for mean-free-paths in the Sabine/Eyring equations except for halls of unusual shape. Also demonstrated is the proper method for calibrating the dodecahedral sound source used for measuring the sound strength G, i.e., the reverberation chamber method. PMID:24437762

  3. A novel LIDAR-based Atmospheric Calibration Method for Improving the Data Analysis of MAGIC

    CERN Document Server

    Fruck, Christian; Zanin, Roberta; Dorner, Daniela; Garrido, Daniel; Mirzoyan, Razmik; Font, Lluis

    2014-01-01

    A new method for analyzing the returns of the custom-made 'micro'-LIDAR system, which is operated along with the two MAGIC telescopes, allows to apply atmospheric corrections in the MAGIC data analysis chain. Such corrections make it possible to extend the effective observation time of MAGIC under adverse atmospheric conditions and reduce the systematic errors of energy and flux in the data analysis. LIDAR provides a range-resolved atmospheric backscatter profile from which the extinction of Cherenkov light from air shower events can be estimated. Knowledge of the extinction can allow to reconstruct the true image parameters, including energy and flux. Our final goal is to recover the source-intrinsic energy spectrum also for data affected by atmospheric extinction from aerosol layers, such as clouds.

  4. A robust and passive method for geometric calibration of large arrays

    CERN Document Server

    Vanwynsberghe, Charles; Marchal, Jacques; Marchiano, Régis; Ollivier, François

    2016-01-01

    This paper presents a complete strategy for the geometry estimation of large microphone arrays of arbitrary shape. Largeness is intended here in both number of microphones (hundreds) and size (few meters). Such arrays can be used for various applications in open or confined spaces like acoustical imaging, source identification, or speech processing. For so large array systems,measuring the geometry by hand is impractical. Therefore a blind passive method is proposed. It is based on the analysis of the background acoustic noise, supposed to be a diffuse field. The proposed strategy is a two-step process. First the pairwise microphone distances are identified by matching their measured coherence function to the one predicted by the diffuse field theory. Second, a robust multidimensional scaling(MDS) algorithm is adapted and implemented. It takes advantage of local characteristics to reduce the set of distances and infer the geometry of the array. This work is an extension of previous studies, and it overcomes u...

  5. The standardization methods of radioactive sources (125I, 131I, 99mTc, and 18F) for calibrating nuclear medicine equipment in Indonesia

    Science.gov (United States)

    Wurdiyanto, G.; Candra, H.

    2016-03-01

    The standardization of radioactive sources (125I, 131I, 99mTc and 18F) to calibrate the nuclear medicine equipment had been carried out in PTKMR-BATAN. This is necessary because the radioactive sources used in the field of nuclear medicine has a very short half-life in other that to obtain a quality measurement results require special treatment. Besides that, the use of nuclear medicine techniques in Indonesia develop rapidly. All the radioactive sources were prepared by gravimetric methods. Standardization of 125I has been carried out by photon- photon coincidence methods, while the others have been carried out by gamma spectrometry methods. The standar sources are used to calibrate a Capintec CRC-7BT radionuclide calibrator. The results shows that calibration factor for Capintec CRC-7BT dose calibrator is 1,03; 1,02; 1,06; and 1,04 for 125I, 131I, 99mTc and 18F respectively, by about 5 to 6% of the expanded uncertainties.

  6. Baseline oxygenation in the brain: Correlation between respiratory-calibration and susceptibility methods.

    Science.gov (United States)

    Fan, Audrey P; Schäfer, Andreas; Huber, Laurentius; Lampe, Leonie; von Smuda, Steffen; Möller, Harald E; Villringer, Arno; Gauthier, Claudine J

    2016-01-15

    New MRI methods for noninvasive imaging of baseline oxygen extraction fraction (OEF) in the brain show great promise. Quantitative O2 imaging (QUO2) applies a biophysical model to measure OEF in tissue from BOLD, cerebral blood flow (CBF), and end-tidal O2 (ETO2) signals acquired during two or more gas manipulations. Alternatively, quantitative susceptibility mapping (QSM) maps baseline OEF along cerebral vessels based on the deoxyhemoblogin (dHb) susceptibility shift between veins and water. However, these approaches have not been carefully compared to each other or to known physiological signals. The aims of this study were to compare OEF values by QUO2 and QSM; and to see if baseline OEF relates to BOLD and CBF changes during a visual task. Simultaneous BOLD and arterial spin labeling (ASL) scans were acquired at 7T in 11 healthy subjects continuously during hypercapnia (5% CO2, 21% O2), hyperoxia (100% O2), and carbogen (5% CO2, 95% O2) for QUO2 analysis. Separate BOLD-ASL scans were acquired during a checkerboard stimulus to identify functional changes in the visual cortex. Gradient echo phase images were also collected at rest for QSM reconstruction of OEF along cerebral veins draining the visual cortex. Mean baseline OEF was (43.5±14)% for QUO2 with two gases, (42.3±17)% for QUO2 with three gases, and (29.4±3)% for QSM across volunteers. Three-gas QUO2 values of OEF correlated with QSM values of OEF (P=0.03). However, Bland-Altman analysis revealed that QUO2 tended to measure higher baseline OEF with respect to QSM, which likely results from underestimation of the hyperoxic BOLD signal and low signal-to-noise ratio of the ASL acquisitions. Across subjects, the percent CBF change during the visual task correlated with OEF measured by 3-gas QUO2 (P<0.04); and by QSM (P=0.035), providing evidence that the new methods measure true variations in brain physiology across subjects.

  7. A new method to calibrate aerodynamic roughness over the Tibetan Plateau using Ensemble Kalman Filter

    Directory of Open Access Journals (Sweden)

    J. H. Lee

    2012-04-01

    Full Text Available Aerodynamic roughness height (Zom is a key parameter required in land surface hydrological model, since errors in heat flux estimations are largely dependent on accurate optimization of this parameter. Despite its significance, it remains an uncertain parameter that is not easily determined. This is mostly because of non-linear relationship in Monin-Obukhov Similarity (MOS and unknown vertical characteristic of vegetation. Previous studies determined aerodynamic roughness using traditional wind profile method, remotely sensed vegetation index, minimization of cost function over MOS relationship or linear regression. However, these are complicated procedures that presume high accuracy for several other related parameters embedded in MOS equations. In order to simplify a procedure and reduce the number of parameters in need, this study suggests a new approach to extract aerodynamic roughness parameter via Ensemble Kalman Filter (EnKF that affords non-linearity and that requires only single or two heat flux measurement. So far, to our knowledge, no previous study has applied EnKF to aerodynamic roughness estimation, while a majority of data assimilation study has paid attention to land surface state variables such as soil moisture or land surface temperature. This approach was applied to grassland in semi-arid Tibetan area and maize on moderately wet condition in Italy. It was demonstrated that aerodynamic roughness parameter can inversely be tracked from data assimilated heat flux analysis. The aerodynamic roughness height estimated in this approach was consistent with eddy covariance result and literature value. Consequently, this newly estimated input adjusted the sensible heat overestimated and latent heat flux underestimated by the original Surface Energy Balance System (SEBS model, suggesting better heat flux estimation especially during the summer Monsoon period. The advantage of this approach over other methodologies is

  8. A case study of an enhanced eutrophication model with stoichiometric zooplankton growth sub-model calibrated by Bayesian method.

    Science.gov (United States)

    Yang, Likun; Peng, Sen; Sun, Jingmei; Zhao, Xinhua; Li, Xia

    2016-05-01

    Urban lakes in China have suffered from severe eutrophication over the past several years, particularly those with relatively small areas and closed watersheds. Many efforts have been made to improve the understanding of eutrophication physiology with advanced mathematical models. However, several eutrophication models ignore zooplankton behavior and treat zooplankton as particles, which lead to the systematic errors. In this study, an eutrophication model was enhanced with a stoichiometric zooplankton growth sub-model that simulated the zooplankton predation process and the interplay among nitrogen, phosphorus, and oxygen cycles. A case study in which the Bayesian method was used to calibrate the enhanced eutrophication model parameters and to calculate the model simulation results was carried out in an urban lake in Tianjin, China. Finally, a water quality assessment was also conducted for eutrophication management. Our result suggests that (1) integration of the Bayesian method and the enhanced eutrophication model with a zooplankton feeding behavior sub-model can effectively depict the change in water quality and (2) the nutrients resulting from rainwater runoff laid the foundation for phytoplankton bloom. PMID:26780061

  9. An X-band radar terrain feature detection method for low-altitude SVS operations and calibration using lidar

    Science.gov (United States)

    Young, Steven D.; Uijt de Haag, Maarten; Campbell, Jacob

    2004-08-01

    To enable safe use of Synthetic Vision Systems at low altitudes, real-time range-to-terrain measurements may be required to ensure the integrity of terrain models stored in the system. This paper reviews and extends previous work describing the application of x-band radar to terrain model integrity monitoring. A method of terrain feature extraction and a transformation of the features to a common reference domain are proposed. Expected error distributions for the extracted features are required to establish appropriate thresholds whereby a consistency-checking function can trigger an alert. A calibration-based approach is presented that can be used to obtain these distributions. To verify the approach, NASA's DC-8 airborne science platform was used to collect data from two mapping sensors. An Airborne Laser Terrain Mapping (ALTM) sensor was installed in the cargo bay of the DC-8. After processing, the ALTM produced a reference terrain model with a vertical accuracy of less than one meter. Also installed was a commercial-off-the-shelf x-band radar in the nose radome of the DC-8. Although primarily designed to measure precipitation, the radar also provides estimates of terrain reflectivity at low altitudes. Using the ALTM data as the reference, errors in features extracted from the radar are estimated. A method to estimate errors in features extracted from the terrain model is also presented.

  10. Calibrating nacelle lidars

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, M.

    2013-01-15

    Nacelle mounted, forward looking wind lidars are beginning to be used to provide reference wind speed measurements for the power performance testing of wind turbines. In such applications, a formal calibration procedure with a corresponding uncertainty assessment will be necessary. This report presents four concepts for performing such a nacelle lidar calibration. Of the four methods, two are found to be immediately relevant and are pursued in some detail. The first of these is a line of sight calibration method in which both lines of sight (for a two beam lidar) are individually calibrated by accurately aligning the beam to pass close to a reference wind speed sensor. A testing procedure is presented, reporting requirements outlined and the uncertainty of the method analysed. It is seen that the main limitation of the line of sight calibration method is the time required to obtain a representative distribution of radial wind speeds. An alternative method is to place the nacelle lidar on the ground and incline the beams upwards to bisect a mast equipped with reference instrumentation at a known height and range. This method will be easier and faster to implement and execute but the beam inclination introduces extra uncertainties. A procedure for conducting such a calibration is presented and initial indications of the uncertainties given. A discussion of the merits and weaknesses of the two methods is given together with some proposals for the next important steps to be taken in this work. (Author)

  11. A method for correcting log-derived temperatures in deep wells, calibrated in the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Waples, D.W.; Pacheco, J.; Vera, A. [Pemex Exploracion y Produccion, Ciudad del Carmen, Campeche (Mexico)

    2004-07-01

    A method for correcting log-derived temperatures In deep wells (3500-6500 m) has been developed by comparing log temperatures from the Gulf of Campeche (Mexican Gulf of Mexico) with DST temperatures in the same wells. The equations developed in this study are modified slightly from those of Waples and Mahadir Ramly (2001), which were calibrated using data from depths <3500 m in Malaysia. The correction depends strongly on time since end of mud circulation (TSC) and, to a much lesser degree, on depth. In this study the true subsurface temperature (Celsius) is given by Ttrue Tsurf +f. }Tmeas-Tsurf 0.001391 }Z-4498 where f=1.32866{sup -0.005289TSC}, Tsurf is the seafloor or land-surface temperature ({sup o}C), Tmeas is the measured log temperature ({sup o}C), TSC is in hours and Z is depth below seafloor in metres. If TSC is unknown, it can be estimated from the trend of TSC with depth. (author)

  12. A method to calibrate channel friction and bathymetry parameters of a Sub-Grid hydraulic model using SAR flood images

    Science.gov (United States)

    Wood, M.; Neal, J. C.; Hostache, R.; Corato, G.; Chini, M.; Giustarini, L.; Matgen, P.; Wagener, T.; Bates, P. D.

    2015-12-01

    Synthetic Aperture Radar (SAR) satellites are capable of all-weather day and night observations that can discriminate between land and smooth open water surfaces over large scales. Because of this there has been much interest in the use of SAR satellite data to improve our understanding of water processes, in particular for fluvial flood inundation mechanisms. Past studies prove that integrating SAR derived data with hydraulic models can improve simulations of flooding. However while much of this work focusses on improving model channel roughness values or inflows in ungauged catchments, improvement of model bathymetry is often overlooked. The provision of good bathymetric data is critical to the performance of hydraulic models but there are only a small number of ways to obtain bathymetry information where no direct measurements exist. Spatially distributed river depths are also rarely available. We present a methodology for calibration of model average channel depth and roughness parameters concurrently using SAR images of flood extent and a Sub-Grid model utilising hydraulic geometry concepts. The methodology uses real data from the European Space Agency's archive of ENVISAT[1] Wide Swath Mode images of the River Severn between Worcester and Tewkesbury during flood peaks between 2007 and 2010. Historic ENVISAT WSM images are currently free and easy to access from archive but the methodology can be applied with any available SAR data. The approach makes use of the SAR image processing algorithm of Giustarini[2] et al. (2013) to generate binary flood maps. A unique feature of the calibration methodology is to also use parameter 'identifiability' to locate the parameters with higher accuracy from a pre-assigned range (adopting the DYNIA method proposed by Wagener[3] et al., 2003). [1] https://gpod.eo.esa.int/services/ [2] Giustarini. 2013. 'A Change Detection Approach to Flood Mapping in Urban Areas Using TerraSAR-X'. IEEE Transactions on Geoscience and Remote

  13. Experimental demonstration of a model-based control design and calibration method for cost optimal euro-VI engine-aftertreatment operation

    NARCIS (Netherlands)

    Mentink, P.R.; Willems, F.P.T.; Kupper, F.; Eijnden, E.A.C. van den

    2013-01-01

    This paper presents a model-based control and calibration design method for online cost-based optimization of engine-aftertreatment operation under all operating conditions. The so-called Integrated Emission Management (IEM) strategy online minimizes the fuel and AbBlue consumption. Based on the act

  14. Application of the Monte Carlo method to the analysis of measurement geometries for the calibration of a HP Ge detector in an environmental radioactivity laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Rodenas, Jose [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Apartado 22012, E-46071 Valencia (Spain)], E-mail: jrodenas@iqn.upv.es; Gallardo, Sergio; Ballester, Silvia; Primault, Virginie [Departamento de Ingenieria Quimica y Nuclear, Universidad Politecnica de Valencia, Apartado 22012, E-46071 Valencia (Spain); Ortiz, Josefina [Laboratorio de Radiactividad Ambiental, Universidad Politecnica de Valencia, Apartado 22012, E-46071 Valencia (Spain)

    2007-10-15

    A gamma spectrometer including an HP Ge detector is commonly used for environmental radioactivity measurements. The efficiency of the detector should be calibrated for each geometry considered. Simulation of the calibration procedure with a validated computer program is an important auxiliary tool for environmental radioactivity laboratories. The MCNP code based on the Monte Carlo method has been applied to simulate the detection process in order to obtain spectrum peaks and determine the efficiency curve for each modelled geometry. The source used for measurements was a calibration mixed radionuclide gamma reference solution, covering a wide energy range (50-2000 keV). Two measurement geometries - Marinelli beaker and Petri boxes - as well as different materials - water, charcoal, sand - containing the source have been considered. Results obtained from the Monte Carlo model have been compared with experimental measurements in the laboratory in order to validate the model.

  15. Comparison among physical and mathematical simulation methods to calibrate the scintillating detector to determine the high energy radionuclides in human body

    International Nuclear Information System (INIS)

    In vivo monitoring of photon emitters requires prior calibration of the detectors in order to obtain factors relate the count rate obtained in measuring the individual with this activity in the body. In this work were compared two calibration methods of a Nal scintillation detector (Tl) 3 x 3 for determination in vivo of 40K: (1) Experimental method using a physical-anthropomorphic simulator called BOMAB and (2) mathematical method using the VMC software (Visual Monte Carlo). Both methods aim at simulation of radionuclide distribution in the human body geometry and interaction of photons with the detector. The obtained results show the similarities and limitations of the evaluated methods for the measurement conditions used

  16. 船载雷达角度零值动态标定方法研究%Research on angle zero dynamic calibration method for ship radar

    Institute of Scientific and Technical Information of China (English)

    李志坚; 胡金辉; 陈小刚

    2013-01-01

    针对船载雷达海上动态环境下角度标校的难题,介绍了船载雷达角度零值动态标定新方法——星体测量法,该方法以高精度的经纬仪为基准,通过雷达与经纬仪联合测量恒星,在同一坐标系下进行数据处理,得到角度零值.同时,本文对各种标定方法的优劣进行研究分析,通过试验验证,与传统坞内标定等方法相比,动态标定新方法优势显著,提高了测角精度.%Aimed at the problem of angle calibration dynamically on the sea for ship radar, the article introduced a new method of angle zero dynamic calibration-star measurement. As a reference,the precision of theodolite was higher. Ship radar and theodolite measured star together and the data was processed in the same coordinate system to get angle zero of radar. The advantages and disadvantages of various calibration method was analyzed. Via the results of experimentation,the angular accuracy of new method was raised obviously compared with traditional dock calibration.

  17. Simultaneous Determination of 6-Mercaptopurine and its Oxidative Metabolites in Synthetic Solutions and Human Plasma using Spectrophotometric Multivariate Calibration Methods

    Directory of Open Access Journals (Sweden)

    Mohammad-Reza Rashidi

    2011-06-01

    Full Text Available Introduction: 6-Mercaptopurine (6MP is an important chemotherapeutic drug in the conventional treatment of childhood acute lymphoblastic leukemia (ALL. It is catabolized to 6-thiouric acid (6TUA through 8-hydroxo-6-mercaptopurine (8OH6MP or 6-thioxanthine (6TX intermediates. Methods: High-performance liquid chromatography (HPLC is usually used to determine the contents of therapeutic drugs, metabolites and other important biomedical analytes in biological samples. In the present study, the multivariate calibration methods, partial least squares (PLS-1 and principle component regression (PCR have been developed and validated for the simultaneous determination of 6MP and its oxidative metabolites (6TUA, 8OH6MP and 6TX without analyte separation in spiked human plasma. Mixtures of 6MP, 8-8OH6MP, 6TX and 6TUA have been resolved by PLS-1 and PCR to their UV spectra. Results: Recoveries (% obtained for 6MP, 8-8OH6MP, 6TX and 6TUA were 94.5-97.5, 96.6-103.3, 95.1-96.9 and 93.4-95.8, respectively, using PLS-1 and 96.7-101.3, 96.2-98.8, 95.8-103.3 and 94.3-106.1, respectively, using PCR. The NAS (Net analyte signal concept was used to calculate multivariate analytical figures of merit such as limit of detection (LOD, selectivity and sensitivity. The limit of detections for 6MP, 8-8OH6MP, 6TX and 6TUA were calculated to be 0.734, 0.439, 0.797 and 0.482 µmol L-1, respectively, using PLS and 0.724, 0.418, 0783 and 0.535 µmol L-1, respectively, using PCR. HPLC was also applied as a validation method for simultaneous determination of these thiopurines in the synthetic solutions and human plasma. Conclusion: Combination of spectroscopic techniques and chemometric methods (PLS and PCR has provided a simple but powerful method for simultaneous analysis of multicomponent mixtures.

  18. Research of Camera Calibration Method Based on Intelligent Optimization%一种基于智能优化的摄像机标定方法研究

    Institute of Scientific and Technical Information of China (English)

    高忠国; 张洪; 王露露; 曹毅

    2011-01-01

    The application of an improved quantum particle swarm optimization algorithm(QPSO)in camera calibration was studied to overcome the drawbacks of traditional optimization algorithms in camera calibration,such as sensitive to original value,poor astringency,and easy to relapse into local optimization.A camera calibration method based on intelligent optimization algorithm was put forward and the calculation procedures were given.Calibration experiments results showed that the method can overcome the drawbacks of traditional optimization algorithms,has higher precision,and meet the application requirements of computer vision in packaging engineering.%针对现有包装设备上对摄像机标定中传统优化算法存在的缺点,如对初始值敏感、收敛性差、易陷入局部最优解等,研究了量子粒子群优化算法在摄像机标定中的应用,提出了一种基于智能优化的摄像机标定方法,并给出了具体的步骤。实验结果表明该标定方法可以克服传统算法的不足,具有较高的精度,可以满足计算机视觉在包装工程中的应用。

  19. A 12-bit, 1 MS/s SAR-ADC for a CZT-based multi-channel gamma-ray imager using a new digital calibration method

    International Nuclear Information System (INIS)

    The successive approximation register-analog to digital converter (SAR-ADC) is widely used in the CdZnTe-based gamma-ray imager because of its outstanding characteristics of low power consumption, relatively high resolution, and small die size. This study proposes a digital bit-by-bit calibration method using an input ramp signal to further improve the conversion precision and power consumption of an SAR-ADC. The proposed method is based on the sub-radix-2 redundant architecture and the perturbation technique. The proposed calibration algorithm is simpler, more stable, and faster than traditional approaches. The prototype chip of the 12-bit, 1 MS/s radiation-hardened SAR-ADC has been designed and fabricated using the TSMC 0.35 μm 2P4M CMOS process. This SAR-ADC consumes 3 mW power and occupies a core area of 856× 802μm2. The digital bit-by-bit calibration algorithm is implemented via MATLAB for testing flexibility. The effective number of bits for this digitally calibrated SAR-ADC reaches 11.77 bits. The converter exhibits high conversion precision, low power consumption, and radiation-hardened design. Therefore, this SAR-ADC is suitable for multi-channel gamma-ray imager applications

  20. Dosimeter calibration facilities and methods at the Radiation Measurement Laboratory of the Centre d'etudes nucleaires, Grenoble

    International Nuclear Information System (INIS)

    At the Centre d'etudes nucleaires, Grenoble, the Radiation Measurement Laboratory, which forms part of the Environmental Protection and Research Department, serves the entire Centre for purposes of dosimetry and the calibration of dose meters. The needs of radiation protection are such that one must have facilities for checking periodically the calibration of radiation-monitoring instruments and developing special dosimetry techniques. It was thought a good idea to arrange for the dosimetry and radiation protection team to assist other groups working at the Centre - in particular, the staff of the biology and radiobiology laboratories - and also bodies outside the framework of the French Commissariat a l'energie atomique. Thus, technical collaboration has been established with, for example, Grenoble's Centre hospitalier universitaire (university clinic), which makes use of the facilities and skills available at the Radiation Measurement Laboratory for solving special dosimetry problems. With the Laboratory's facilities it is possible to calibrate dose meters for gamma, beta and neutron measurements

  1. 精密铂电阻温度计的校准方法%Study of precision platinum resistance thermometer calibration method

    Institute of Scientific and Technical Information of China (English)

    姚丽芳; 陈宇; 郑伟; 朱家良

    2014-01-01

    In this article, we introduce the performance characteristic of precision platinum resistance thermometer and how to calibrate it within 0 to 660.323 degree centigrade. We put forward that the precision platinum resistance thermometer whose upper limit temperature is higher than 450℃ can be annealed at ceiling temperature in instruction manual. When we calibrate precision platinum resistance thermometer with fixed point method, we can use melting point instead of freezing point. And we focus on the feasibility of calibrating precision platinum resistance thermometer with comparison method instead of fixed point method and using simplified formula to get the calibration results. Meanwhile, we point out the thermal effect influence on calibration.%介绍了精密铂电阻温度计的特性及0~660.323℃温度范围内精密铂电阻温度计的校准方法。提出对测量上限温度高于450℃的精密铂电阻温度计可参考使用说明书要求进行上限温度退火,进行定点法校准时,可采用熔化点温坪替代凝固点温坪,对于无法进行定点法校准的精密铂电阻温度计,可采用比较法校准及采用简化公式计算各项参数的可行性,同时指出自热效应对测量的影响。

  2. 混合车流微观仿真模型校正方法研究%A Calibration Method of Microscopic Simulation Models for Mixed Traffic Flow

    Institute of Scientific and Technical Information of China (English)

    李嘉; 王子浜; 董海文

    2011-01-01

    A microscopic method may generate more accurate results in simulation model calibration for the mixed traffic flow with greatly different vehicle characteristics. In this paper, a method for mixed traffic flow is developed, which focuses on sensitivity analysis of model parameters, parameters values calibration, and result evaluations, for different vehicle and link types. An example of calibrating microscopic simulation models is carried out using CORSIM. The results show that, when the average travel time in CORSIM is satisfied with the targets, vehicle-type calibration can effectively calibrate the discrepancy between CORSIM and the actual one, and keep the simulated vehicle types in line with actual vehicle types. The method is proven to be effective.%为了合理准确地模拟车辆间性能差异较大的混合车流,需要从微观层面来校正仿真模型.针对不同车型和不同道路设施单元,提出了一套基于混合车流特性的微观仿真模型校正方法,包括参数的敏感性分析、模型参数的校正及校正效果评价等.最后,借助微观仿真软件CORSIM对高速公路路段仿真模型进行实例验证.结果显示,在所有车辆平均行程时间满足校正目标的情况下,分车型校正能够保证仿真车型合理表达实际车型的交通特性,证实了校正方法的可行性.

  3. Method for the in Situ Calibration of a Passive Phosphate Sampler in Estuarine and Marine Waters

    OpenAIRE

    O'Brien, D. S.; Booij, K.; Hawker, D.W.; Mueller, J.F.

    2011-01-01

    Passive samplers for phosphate were calibrated in the laboratory over a range of flow velocities (0-27 cm s(-1)) and ionic strengths (0-0.62 mol kg(-1)). The observed sampling rates were between 0.006 and 0.20 L d(-1). An empirical model allowed the estimation of these sampling rates with a precision of 8.5%. Passive flow monitors (PFMs), based on gypsum dissolution rates, were calibrated for the same range of flow velocities and ionic strength. Mass loss rates of the PFMs increased with incr...

  4. Segment Based Camera Calibration

    Institute of Scientific and Technical Information of China (English)

    马颂德; 魏国庆; 等

    1993-01-01

    The basic idea of calibrating a camera system in previous approaches is to determine camera parmeters by using a set of known 3D points as calibration reference.In this paper,we present a method of camera calibration in whih camera parameters are determined by a set of 3D lines.A set of constraints is derived on camea parameters in terms of perspective line mapping.Form these constraints,the same perspective transformation matrix as that for point mapping can be computed linearly.The minimum number of calibration lines is 6.This result generalizes that of Liu,Huang and Faugeras[12] for camera location determination in which at least 8 line correspondences are required for linear computation of camera location.Since line segments in an image can be located easily and more accurately than points,the use of lines as calibration reference tends to ease the computation in inage preprocessing and to improve calibration accuracy.Experimental results on the calibration along with stereo reconstruction are reported.

  5. A simple atomic force microscopy calibration method for direct measurement of surface energy on nanostructured surfaces covered with molecularly thin liquid films

    International Nuclear Information System (INIS)

    A simple calibration method is described for the determination of surface energy by atomic force microscopy (AFM) pull-off force measurements on nanostructured surfaces covered with molecularly thin liquid films. The method is based on correlating pull-off forces measured in arbitrary units on a nanostructured surface with pull-off forces measured on macroscopically smooth dip-coated gauge surfaces with known surface energy. The method avoids the need for complex calibration of the AFM cantilever stiffness and the determination of the radius of curvature of the AFM tip. Both of the latter measurements are associated with indirect and less accurate measurements of surface energy based on various contact mechanics adhesion models.

  6. A variable acceleration calibration system

    Science.gov (United States)

    Johnson, Thomas H.

    2011-12-01

    A variable acceleration calibration system that applies loads using gravitational and centripetal acceleration serves as an alternative, efficient and cost effective method for calibrating internal wind tunnel force balances. Two proof-of-concept variable acceleration calibration systems are designed, fabricated and tested. The NASA UT-36 force balance served as the test balance for the calibration experiments. The variable acceleration calibration systems are shown to be capable of performing three component calibration experiments with an approximate applied load error on the order of 1% of the full scale calibration loads. Sources of error are indentified using experimental design methods and a propagation of uncertainty analysis. Three types of uncertainty are indentified for the systems and are attributed to prediction error, calibration error and pure error. Angular velocity uncertainty is shown to be the largest indentified source of prediction error. The calibration uncertainties using a production variable acceleration based system are shown to be potentially equivalent to current methods. The production quality system can be realized using lighter materials and a more precise instrumentation. Further research is needed to account for balance deflection, forcing effects due to vibration, and large tare loads. A gyroscope measurement technique is shown to be capable of resolving the balance deflection angle calculation. Long term research objectives include a demonstration of a six degree of freedom calibration, and a large capacity balance calibration.

  7. Calibration method for a photoacoustic system for real time source apportionment of light absorbing carbonaceous aerosol based on size distribution measurements

    Science.gov (United States)

    Utry, Noemi; Ajtai, Tibor; Pinter, Mate; Orvos, Peter I.; Szabo, Gabor; Bozoki, Zoltan

    2016-04-01

    In this study, we introduce a calibration method with which sources of light absorbing carbonaceous particulate matter (LAC) can be apportioned in real time based on multi wavelength optical absorption measurements with a photoacoustic system. The method is primary applicable in wintry urban conditions when LAC is dominated by traffic and biomass burning. The proposed method was successfully tested in a field campaign in the city center of Szeged, Hungary during winter time where the dominance of traffic and wood burning aerosol has been experimentally demonstrated earlier. With the help of the proposed calibration method a relationship between the measured Aerosol Angström Exponent (AAE) and the number size distribution can be deduced. Once the calibration curve is determined, the relative strength of the two pollution sources can be deduced in real time as long as the light absorbing fraction of PM is exclusively related to traffic and wood burning. This assumption is indirectly confirmed in the presented measurement campaign by the fact that the measured size distribution is composed of two unimodal size distributions identified to correspond to traffic and wood burning aerosols. The proposed method offers the possibility of replacing laborious chemical analysis with simple in-situ measurement of aerosol size distribution data.

  8. STELLAR COLOR REGRESSION: A SPECTROSCOPY-BASED METHOD FOR COLOR CALIBRATION TO A FEW MILLIMAGNITUDE ACCURACY AND THE RECALIBRATION OF STRIPE 82

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Haibo; Liu, Xiaowei [Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871 (China); Xiang, Maosheng; Huang, Yang; Zhang, Huihua; Chen, Bingqiu, E-mail: yuanhb4861@pku.edu.cn, E-mail: x.liu@pku.edu.cn [Department of Astronomy, Peking University, Beijing 100871 (China)

    2015-02-01

    In this paper we propose a spectroscopy-based stellar color regression (SCR) method to perform accurate color calibration for modern imaging surveys, taking advantage of millions of stellar spectra now available. The method is straightforward, insensitive to systematic errors in the spectroscopically determined stellar atmospheric parameters, applicable to regions that are effectively covered by spectroscopic surveys, and capable of delivering an accuracy of a few millimagnitudes for color calibration. As an illustration, we have applied the method to the Sloan Digital Sky Survey (SDSS) Stripe 82 data. With a total number of 23,759 spectroscopically targeted stars, we have mapped out the small but strongly correlated color zero-point errors present in the photometric catalog of Stripe 82, and we improve the color calibration by a factor of two to three. Our study also reveals some small but significant magnitude dependence errors in the z band for some charge-coupled devices (CCDs). Such errors are likely to be present in all the SDSS photometric data. Our results are compared with those from a completely independent test based on the intrinsic colors of red galaxies presented by Ivezić et al. The comparison, as well as other tests, shows that the SCR method has achieved a color calibration internally consistent at a level of about 5 mmag in u – g, 3 mmag in g – r, and 2 mmag in r – i and i – z. Given the power of the SCR method, we discuss briefly the potential benefits by applying the method to existing, ongoing, and upcoming imaging surveys.

  9. Noninvasive method for the calibration of the peak voltage (kVp) meters; Implantacao de metodo nao invasivo para calibracao de medidores de tensao de pico (kVp)

    Energy Technology Data Exchange (ETDEWEB)

    Macedo, E.M.; Navarro, M.V.T.; Pereira, L.; Garcia, I.F.M.; Navarro, V.C.C., E-mail: ematosmacedo@gmail.com [Instituto Federal da Bahia (LABPROSAUD/IFBA), Salvador-BA (Brazil). Laboratorio de Produtos para a Saude

    2015-07-01

    Quality control in diagnostic radiology is one of the mechanisms that minimize radiation exposure, and the measurement of tube voltage is one of the main test in these procedures. So, the calibration of non-invasive tube voltage meters is essential to maintain the metrological reliability of quality control tests. Thus, this work describes the implementation of the calibration methodology of the quantity tube peak voltage by the substitution method, using non-invasive standard meter, at LABPROSAUD-IFBA. The results showed great performance and when compared with calibrations by invasive methods, showed maximum difference of 4%, contemplated in the uncertainty ranges of the calibrations. (author)

  10. 基于OpenCV的摄像机标定方法实现%Camera calibration method based on OpenCV

    Institute of Scientific and Technical Information of China (English)

    王冬; 夏乙; 殷木一; 陈玉林; 郑程; 刘海林

    2013-01-01

    In order to realize the camera calibration in 3D reconstruction system,a calculation method based on an ideal camera model,in which the influences of lens radial distortion and tangential distortion were brought,was adopted,and a camera calibration algorithm based on OpenCV(open source computer vision library)was developed in Visual C++ environment. The calibration result was compared with that based on Matlab camera calibration tool kit. The experimental result shows that the pro⁃posed method has the advantages of high calibration precision and good robust,and can meet the needs of actual application and other computer vision systems.%  为了实现在三维重建系统中的对摄像机进行标定的目的,采用理想摄像机成像模型为基础,在模型中引入透镜径向畸变和切向畸变影响的计算方法。在VC++环境下开发了一种基于OpenCV算法库的摄像机标定算法,并同基于Mat⁃lab摄像机标定工具箱的标定结果进行了比较。实验结果表明,该方法具有标定精度高、鲁棒性好等优点,可以满足增强现实和其他计算机视觉系统的需要。

  11. Camera calibration method based on OpenCV%基于OpenCV的摄像机标定方法实现

    Institute of Scientific and Technical Information of China (English)

    王冬; 夏乙; 殷木一; 陈玉林; 郑程; 刘海林

    2013-01-01

    In order to realize the camera calibration in 3D reconstruction system,a calculation method based on an ideal camera model,in which the influences of lens radial distortion and tangential distortion were brought,was adopted,and a camera calibration algorithm based on OpenCV(open source computer vision library)was developed in Visual C++ environment. The calibration result was compared with that based on Matlab camera calibration tool kit. The experimental result shows that the pro⁃posed method has the advantages of high calibration precision and good robust,and can meet the needs of actual application and other computer vision systems.%  为了实现在三维重建系统中的对摄像机进行标定的目的,采用理想摄像机成像模型为基础,在模型中引入透镜径向畸变和切向畸变影响的计算方法。在VC++环境下开发了一种基于OpenCV算法库的摄像机标定算法,并同基于Mat⁃lab摄像机标定工具箱的标定结果进行了比较。实验结果表明,该方法具有标定精度高、鲁棒性好等优点,可以满足增强现实和其他计算机视觉系统的需要。

  12. A BAYESIAN METHOD FOR CALCULATING REAL-TIME QUANTITATIVE PCR CALIBRATION CURVES USING ABSOLUTE PLASMID DNA STANDARDS

    Science.gov (United States)

    In real-time quantitative PCR studies using absolute plasmid DNA standards, a calibration curve is developed to estimate an unknown DNA concentration. However, potential differences in the amplification performance of plasmid DNA compared to genomic DNA standards are often ignore...

  13. Experimental Approach of Reflectance Based Vicarious Calibration Method for Solar Reflectance Wavelength Region of Sensor Onboard Remote Sensing Satellites

    Directory of Open Access Journals (Sweden)

    Kohei Arai

    2013-12-01

    Full Text Available Experimental approach of reflectance based vicarious calibration of solar reflectance wavelength region of mission instruments onboard remote sensing satellites is conducted. As an example, vicarious calibration of ASTER/VNIR with estimated aerosol refractive index and size distribution that depends on atmospheric conditions is discussed. Strange solution of estimated refractive index and size distribution may occurred due to the fact that solution fell into one of local minima in the inversion process for phase function fitting between measured and estimated with assumed refractive index and size distribution. This paper describes atmospheric conditions that may induce such a situation. Namely, it may occur when the atmospheric optical depth is too thin and or Junge parameter is too small. In such case, refractive index and size distribution estimation accuracy is poor. A relation between refractive index and size distribution estimation accuracy and estimation accuracy of the Top of the Atmosphere (TOA radiance (vicarious calibration accuracy is also clarified in particular for ASTER/VNIR vicarious calibration. It is found that 10% of the refractive index and size distribution estimation error causes approximately 1.3% of TOA radiance estimation error.

  14. The suitable dose range for the calibration of EBT2 film by the PDD method with a comparison of two curve fitting algorithms

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Liyun, E-mail: cliyun2000@gmail.com [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Ho, Sheng-Yow [Department of Radiation Oncology, Chi Mei Medical Center, Liouying, Tainan, Taiwan (China); Lee, Tsair-Fwu [Medical Physics and Informatics Laboratory, Department of Electronics Engineering, National Kaohsiung University of Applied Sciences, Kaohsiung, Taiwan (China); Yeh, Shyh-An [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Department of Radiation Oncology, E-Da Hospital, Kaohsiung, Taiwan (China); Ding, Hueisch-Jy [Department of Medical Imaging and Radiological Sciences, I-Shou University, Kaohsiung, Taiwan (China); Chen, Pang-Yu, E-mail: pangyuchen@yahoo.com.tw [Department of Radiation Oncology, Sinlau Christian Hospital, Tainan, Taiwan (China)

    2015-03-21

    EBT2 film is a convenient dosimetry quality-assurance (QA) tool with high 2D dosimetry resolution and a self-development property for use in verifications of radiation therapy treatment planning and special projects; however, the user will suffer from a relatively higher degree of uncertainty (more than ±6% by Hartmann et al. [29]), and the trouble of cutting one piece of film into small pieces and then reintegrating them each time. To prevent this tedious cutting work, and save calibration time and budget, a dose range analysis is presented in this study for EBT2 film calibration using the Percentage–Depth–Dose (PDD) method. Different combinations of the three dose ranges, 9–26 cGy, 33–97 cGy and 109–320 cGy, with two types of curve fitting algorithms, film pixel values and net optical densities converting into doses, were tested and compared. With the lowest error and acceptable inaccuracy of less than 3 cGy for the clinical dose range (9–320 cGy), a single film calibrated by the net optical density algorithm with the dose range 109–320 cGy was suggested for routine calibration.

  15. Laboratory radiation calibration method of Hadamard transform imaging spectrometer%Hadamard变换成像光谱仪实验室辐射定标方法

    Institute of Scientific and Technical Information of China (English)

    白军科; 刘学斌; 闫鹏; 胡炳樑

    2013-01-01

      Hadamard变换成像光谱仪采用多通道探测数字变换技术实现光谱成像.主要介绍了基于数字微镜阵列器件的Hadamard变换成像光谱仪的工作原理与仪器结构,研究设计了一套适用于该Hadamard变换成像光谱仪的实验室辐射定标方案.用远距点光源光路进行CMOS探测器像元响应不均匀性修正,获得相对定标精度达到4.6%;采用太阳模拟光源和均匀平行光路,用光谱辐射度计实现标准辐射亮度的传递进行光谱辐射定标,绝对定标精度达到8.92%.通过实物成像,Hadamard变换成像光谱仪的实验室辐射定标方法精确、实用.%Hadamard transform imaging spectrometer is a multi -channel detection digital transform spectrometer detection technology. The spectromter used this technology to achieving spectral imaging. Based on the digital micromirror array device of the Hadamard transform spectrometer working principles and the instrument, a series of precision laboratory calibration methods were researched and employed for the Hadamard transform imaging spectrometer. A point light source in long distance was used for the pixel response nonuniformity correction of the CMOS detector. The uncertainty of the relative calibration was 4.6%. Solar simulator and spectral radiometer were used in absolute radiation calibration of the whole system, and the uncertainty of the absolute radiation calibration was 8.92%. Both of the uncertainty of relative calibration and the uncertainty of the absolute radiation calibration met the requirements of the projection. By actual objects imaging, the laboratory calibration methods of the Hadamard transform imaging spectrometer are proved accurate.

  16. On the method of calibration of the energy dispersive EXAFS beamline at Indus-2 and fitting theoretical model to the EXAFS spectrum

    Indian Academy of Sciences (India)

    Abhijeet Gaur; Ajita Johari; B D Shrivastava; D C Gaur; S N Jha; D Bhattacharyya; A Poswal; S K Deb

    2011-06-01

    A procedure for calibration of the recently developed energy dispersive EXAFS beamline at the Indus-2 synchrotron source at RRCAT, Indore, India has been described. The procedure involves recording of absorption spectra of two standard samples, whose absorption edge energies are well-established. Two methods have been considered for calibration. In the first method, the position of the first maximum of the derivative of absorption curve is taken as the position of the edge energy. In the second method, the position of the point at half edge step in the absorption curve is taken as the position of the edge energy. It has been shown that only the first method gives same values of dispersion even when the beam current is varied and should be used for calibrating the experimental spectra. Further, it is recommended that the performance of the beamline for a particular setting should be checked by recording and analysing EXAFS of a standard. Hence, the procedure for analysis and extracting information about the various parameters that can be determined by fitting the EXAFS data with a theoretical model has also been described, by taking the example of -absorption spectra of copper metal foil recorded on this beamline.

  17. Energy calibration via correlation

    CERN Document Server

    Maier, Daniel

    2015-01-01

    The main task of an energy calibration is to find a relation between pulse-height values and the corresponding energies. Doing this for each pulse-height channel individually requires an elaborated input spectrum with an excellent counting statistics and a sophisticated data analysis. This work presents an easy to handle energy calibration process which can operate reliably on calibration measurements with low counting statistics. The method uses a parameter based model for the energy calibration and concludes on the optimal parameters of the model by finding the best correlation between the measured pulse-height spectrum and multiple synthetic pulse-height spectra which are constructed with different sets of calibration parameters. A CdTe-based semiconductor detector and the line emissions of an 241 Am source were used to test the performance of the correlation method in terms of systematic calibration errors for different counting statistics. Up to energies of 60 keV systematic errors were measured to be le...

  18. Scanner calibration revisited

    Directory of Open Access Journals (Sweden)

    Pozhitkov Alexander E

    2010-07-01

    Full Text Available Abstract Background Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2. reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Methods Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. Results We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Conclusions Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides.

  19. Thermal conductivity measurements of high and low thermal conductivity films using a scanning hot probe method in the 3ω mode and novel calibration strategies.

    Science.gov (United States)

    Wilson, Adam A; Muñoz Rojo, Miguel; Abad, Begoña; Perez, Jaime Andrés; Maiz, Jon; Schomacker, Jason; Martín-Gonzalez, Marisol; Borca-Tasciuc, Diana-Andra; Borca-Tasciuc, Theodorian

    2015-10-01

    This work discusses measurement of thermal conductivity (k) of films using a scanning hot probe method in the 3ω mode and investigates the calibration of thermal contact parameters, specifically the thermal contact resistance (R(th)C) and thermal exchange radius (b) using reference samples with different thermal conductivities. R(th)C and b were found to have constant values (with b = 2.8 ± 0.3 μm and R(th)C = 44,927 ± 7820 K W(-1)) for samples with thermal conductivity values ranging from 0.36 W K(-1) m(-1) to 1.1 W K(-1) m(-1). An independent strategy for the calibration of contact parameters was developed and validated for samples in this range of thermal conductivity, using a reference sample with a previously measured Seebeck coefficient and thermal conductivity. The results were found to agree with the calibration performed using multiple samples of known thermal conductivity between 0.36 and 1.1 W K(-1) m(-1). However, for samples in the range between 16.2 W K(-1) m(-1) and 53.7 W K(-1) m(-1), calibration experiments showed the contact parameters to have considerably different values: R(th)C = 40,191 ± 1532 K W(-1) and b = 428 ± 24 nm. Finally, this work demonstrates that using these calibration procedures, measurements of both highly conductive and thermally insulating films on substrates can be performed, as the measured values obtained were within 1-20% (for low k) and 5-31% (for high k) of independent measurements and/or literature reports. Thermal conductivity results are presented for a SiGe film on a glass substrate, Te film on a glass substrate, polymer films (doped with Fe nano-particles and undoped) on a glass substrate, and Au film on a Si substrate.

  20. Thermal conductivity measurements of high and low thermal conductivity films using a scanning hot probe method in the 3ω mode and novel calibration strategies.

    Science.gov (United States)

    Wilson, Adam A; Muñoz Rojo, Miguel; Abad, Begoña; Perez, Jaime Andrés; Maiz, Jon; Schomacker, Jason; Martín-Gonzalez, Marisol; Borca-Tasciuc, Diana-Andra; Borca-Tasciuc, Theodorian

    2015-10-01

    This work discusses measurement of thermal conductivity (k) of films using a scanning hot probe method in the 3ω mode and investigates the calibration of thermal contact parameters, specifically the thermal contact resistance (R(th)C) and thermal exchange radius (b) using reference samples with different thermal conductivities. R(th)C and b were found to have constant values (with b = 2.8 ± 0.3 μm and R(th)C = 44,927 ± 7820 K W(-1)) for samples with thermal conductivity values ranging from 0.36 W K(-1) m(-1) to 1.1 W K(-1) m(-1). An independent strategy for the calibration of contact parameters was developed and validated for samples in this range of thermal conductivity, using a reference sample with a previously measured Seebeck coefficient and thermal conductivity. The results were found to agree with the calibration performed using multiple samples of known thermal conductivity between 0.36 and 1.1 W K(-1) m(-1). However, for samples in the range between 16.2 W K(-1) m(-1) and 53.7 W K(-1) m(-1), calibration experiments showed the contact parameters to have considerably different values: R(th)C = 40,191 ± 1532 K W(-1) and b = 428 ± 24 nm. Finally, this work demonstrates that using these calibration procedures, measurements of both highly conductive and thermally insulating films on substrates can be performed, as the measured values obtained were within 1-20% (for low k) and 5-31% (for high k) of independent measurements and/or literature reports. Thermal conductivity results are presented for a SiGe film on a glass substrate, Te film on a glass substrate, polymer films (doped with Fe nano-particles and undoped) on a glass substrate, and Au film on a Si substrate. PMID:26335503

  1. A Modeling and Calibration Method of Portable Vision Metrology%一种移动视觉测量系统的建模及标定方法

    Institute of Scientific and Technical Information of China (English)

    谭文斌; 李醒飞; 刘超; 朱嘉

    2014-01-01

    针对一种立柱式二维移动视觉测量系统,提出了其数学模型的建立和标定方法。分析了测量原理和系统组成,并通过对运动定位和摄像机成像的独立建模,构建了符合测量原理的整体数学模型。标定时,在完成对定位误差等13项几何误差标定的基础上,通过移动摄像机使圆孔靶标的像平均分布在摄像机的像面上,根据靶标的工作台位置、像点坐标、以及测量时对应的运动机构移动量,利用最小二乘非线性拟合方法实现对摄像机成像模型参数的标定。实验结果表明:经建模和标定后,测量平均误差为1.8μm。利用该方法进行移动视觉测量系统的建模和标定,可以有效地保证系统的测量精度。%A mathematical model and calibration method is proposed for column two-dimensional portable vision metrology. The analysis of the measuring principle and system components is given. The overall mathematical model in line with measuring principle is established based on the exercise of independent positioning and camera imaging model. In the process of calibration, firstly, the calibration of geometric errors such as the positioning error is completed. Then, the image of round hole is evenly distributed in the image plane of the camera by moving the camera. At last, the calibration of camera imaging model parameters is achieved using nonlinear least squares fitting method, according to the target workbench position, pixel coordinates and the amount of the corresponding moving mechanism moves. Results show that the average error of measurement is 1.8μm by modeling and calibration. The modeling and calibration method of portable vision metrology can effectively improve the system accuracy.

  2. An absolute calibration method of an ethyl alcohol biosensor based on wavelength-modulated differential photothermal radiometry

    International Nuclear Information System (INIS)

    In this work, laser-based wavelength-modulated differential photothermal radiometry (WM-DPTR) is applied to develop a non-invasive in-vehicle alcohol biosensor. WM-DPTR features unprecedented ethanol-specificity and sensitivity by suppressing baseline variations through a differential measurement near the peak and baseline of the mid-infrared ethanol absorption spectrum. Biosensor signal calibration curves are obtained from WM-DPTR theory and from measurements in human blood serum and ethanol solutions diffused from skin. The results demonstrate that the WM-DPTR-based calibrated alcohol biosensor can achieve high precision and accuracy for the ethanol concentration range of 0-100 mg/dl. The high-performance alcohol biosensor can be incorporated into ignition interlocks that could be fitted as a universal accessory in vehicles in an effort to reduce incidents of drinking and driving

  3. An absolute calibration method of an ethyl alcohol biosensor based on wavelength-modulated differential photothermal radiometry

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yi Jun; Mandelis, Andreas, E-mail: mandelis@mie.utoronto.ca [Department of Mechanical and Industrial Engineering, Center for Advanced Diffusion-Wave Technologies (CADIFT), University of Toronto, Toronto, Ontario M5S 3G8 (Canada); Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario M5S 3G9 (Canada); Guo, Xinxin [Department of Mechanical and Industrial Engineering, Center for Advanced Diffusion-Wave Technologies (CADIFT), University of Toronto, Toronto, Ontario M5S 3G8 (Canada)

    2015-11-15

    In this work, laser-based wavelength-modulated differential photothermal radiometry (WM-DPTR) is applied to develop a non-invasive in-vehicle alcohol biosensor. WM-DPTR features unprecedented ethanol-specificity and sensitivity by suppressing baseline variations through a differential measurement near the peak and baseline of the mid-infrared ethanol absorption spectrum. Biosensor signal calibration curves are obtained from WM-DPTR theory and from measurements in human blood serum and ethanol solutions diffused from skin. The results demonstrate that the WM-DPTR-based calibrated alcohol biosensor can achieve high precision and accuracy for the ethanol concentration range of 0-100 mg/dl. The high-performance alcohol biosensor can be incorporated into ignition interlocks that could be fitted as a universal accessory in vehicles in an effort to reduce incidents of drinking and driving.

  4. An absolute calibration method of an ethyl alcohol biosensor based on wavelength-modulated differential photothermal radiometry

    Science.gov (United States)

    Liu, Yi Jun; Mandelis, Andreas; Guo, Xinxin

    2015-11-01

    In this work, laser-based wavelength-modulated differential photothermal radiometry (WM-DPTR) is applied to develop a non-invasive in-vehicle alcohol biosensor. WM-DPTR features unprecedented ethanol-specificity and sensitivity by suppressing baseline variations through a differential measurement near the peak and baseline of the mid-infrared ethanol absorption spectrum. Biosensor signal calibration curves are obtained from WM-DPTR theory and from measurements in human blood serum and ethanol solutions diffused from skin. The results demonstrate that the WM-DPTR-based calibrated alcohol biosensor can achieve high precision and accuracy for the ethanol concentration range of 0-100 mg/dl. The high-performance alcohol biosensor can be incorporated into ignition interlocks that could be fitted as a universal accessory in vehicles in an effort to reduce incidents of drinking and driving.

  5. Radiochromic film dosimetry with flatbed scanners: A fast and accurate method for dose calibration and uniformity correction with single film exposure

    International Nuclear Information System (INIS)

    Film dosimetry is an attractive tool for dose distribution verification in intensity modulated radiotherapy (IMRT). A critical aspect of radiochromic film dosimetry is the scanner used for the readout of the film: the output needs to be calibrated in dose response and corrected for pixel value and spatial dependent nonuniformity caused by light scattering; these procedures can take a long time. A method for a fast and accurate calibration and uniformity correction for radiochromic film dosimetry is presented: a single film exposure is used to do both calibration and correction. Gafchromic EBT films were read with two flatbed charge coupled device scanners (Epson V750 and 1680Pro). The accuracy of the method is investigated with specific dose patterns and an IMRT beam. The comparisons with a two-dimensional array of ionization chambers using a 18x18 cm2 open field and an inverse pyramid dose pattern show an increment in the percentage of points which pass the gamma analysis (tolerance parameters of 3% and 3 mm), passing from 55% and 64% for the 1680Pro and V750 scanners, respectively, to 94% for both scanners for the 18x18 open field, and from 76% and 75% to 91% for the inverse pyramid pattern. Application to an IMRT beam also shows better gamma index results, passing from 88% and 86% for the two scanners, respectively, to 94% for both. The number of points and dose range considered for correction and calibration appears to be appropriate for use in IMRT verification. The method showed to be fast and to correct properly the nonuniformity and has been adopted for routine clinical IMRT dose verification

  6. A novel method for the preparation of large-area 90Sr/90Y sources for the calibration of hand contamination monitors

    International Nuclear Information System (INIS)

    This paper describes a method for the preparation of large-area 90Sr/90Y polymer film sources for the calibration of hand contamination monitors. The process consists of solvent extraction of predictable quantity of 90Sr into an organic solvent containing di-tert-butyl-cyclohexano-18-crown-6 (DCH18C6), formation of a polymeric solution of poly(methyl methacrylate) (PMMA), pouring the 90Sr-embedded polymer solution over a surface of a defined area followed by evaporation to create a thin film and peeling-off of the radioactive PMMA film. Quality control tests of the radioactive films were carried out to ensure nonleachability, uniform distribution of activity and stability. Sources having 5 kBq±428 Bq were prepared using this method and routinely used for calibration of contamination monitors. - Highlights: • Preparation of large-area 90Sr/90Y sources for the calibration of hand contamination monitors. • Extraction of 90Sr/90Y activity followed by preparation of a polymeric solution. • Pouring the radioactive polymer solution on a surface of a defined area. • Quality evaluation of the sources

  7. Metrological models and calibration pads in the system of radioecological investigations over large territories by the method of gamma-ray spectrometry

    Science.gov (United States)

    Khaykovich, I. M.; Serykh, A. S.; Luchin, I. A.; Fominykh, V. I.

    1995-10-01

    A comparative evaluation has been earned out on models for the metrological assurance of instrumental methods which are designed to assess the composition of natural formations when studying radiation situations over large territories, and which are based on spectrometric measurements of γ-radiation from natural beds. Recommendations are given concerning the choice of metrological models in relation to the solution of the main radioecological task. i.e. investigation of the distributions of radionuclides of artificial (technogenic) origin and natural radioactive elements. Here we describe the principles for the selection of calibration pads which correspond to the chosen models; also the procedures for their certification and application for calibration measuring instruments—portable, car-borne and airborne γ-ray spectrometers (multi-channel geophysical γ-radiometers).

  8. 基于OpenCV算法库的摄像机标定方法%Camera Calibration Method Based on OpenCV Algorithm Library

    Institute of Scientific and Technical Information of China (English)

    刘国平; 蔡建平

    2011-01-01

    通过分析摄像机的透视投影成像模型和四个笛卡尔坐标系之间的变换关系,从而明确摄像机标定的目的就是求解其内外参数。比较常用标定方法的优缺点,在VC++环境下开发了一种基于OpencV算法库的摄像机标定程序,实验结果表明,该程序能自动、快速、精确地标定摄像机。%Through analyzing the perspective imaging model and coordinate transformations between four different Cartesian coordinate systems, a camera calibration method based on OpenCV algorithm library is presented. The camera calibration aims to solve the intrin

  9. Use of Radiometrically Calibrated Flat-Plate Calibrators in Calibration of Radiation Thermometers

    Science.gov (United States)

    Cárdenas-García, D.; Méndez-Lango, E.

    2015-08-01

    Most commonly used, low-temperature, infrared thermometers have large fields of view sizes that make them difficult to be calibrated with narrow aperture blackbodies. Flat-plate calibrators with large emitting surfaces have been proposed for calibrating these infrared thermometers. Because the emissivity of the flat plate is not unity, its radiance temperature is wavelength dependent. For calibration, the wavelength pass band of the device under test should match that of the reference infrared thermometer. If the device under test and reference radiometer have different pass bands, then it is possible to calculate the corresponding correction if the emissivity of the flat plate is known. For example, a correction of at is required when calibrating a infrared thermometer with a "" radiometrically calibrated flat-plate calibrator. A method is described for using a radiometrically calibrated flat-plate calibrator that covers both cases of match and mismatch working wavelength ranges of a reference infrared thermometer and infrared thermometers to be calibrated with the flat-plate calibrator. Also, an application example is included in this paper.

  10. On chromatic and geometrical calibration

    DEFF Research Database (Denmark)

    Folm-Hansen, Jørgen

    1999-01-01

    we present the implementation of a complete calibration method for an accurate colour texture measurement device called VMX2000, the calibration for uneven laser sheet illumination in a flow measuring system and the use of automatic detection of calibration targets for a DLT/warping in a 3D PIV......The main subject of the present thesis is different methods for the geometrical and chromatic calibration of cameras in various environments. For the monochromatic issues of the calibration we present the acquisition of monochrome images, the classic monochrome aberrations and the various sources...... of non-uniformity of the illumination of the image plane. Only the image deforming aberrations and the non-uniformity of illumination are included in the calibration models. The topics of the pinhole camera model and the extension to the Direct Linear Transform (DLT) are described. It is shown how...

  11. Standardization of 64Cu and 68Ga by the 4π(PC)β-γ coincidence method and calibration of the ionization chamber.

    Science.gov (United States)

    Sahagia, M; Luca, A; Antohe, A; Ivan, C

    2012-09-01

    The paper treats the application of the 4π(PC)β-γ coincidence method for the standardization of the radionuclides (64)Cu and (68)Ga. The general coincidence equations are written. Two types of extrapolation were described and used in measurement: the positron-annihilation coincidence, and the counting of all emitted radiations; both methods are compared with respect to results, advantages and drawbacks. The impurities' content correction was applied. The standardized solutions were used to calibrate the ionization chamber CENTRONIC IG12/20A and to determine the gamma-rays emission intensities.

  12. Calibration of a Soil Water Uptake Model Using Model Ensemble and Prior Information in a Semiarid Environment Using Global and Local Search Methods

    Science.gov (United States)

    Maneta Lopez, M. P.; Wallender, W. W.; Schnabel, S. C.

    2007-12-01

    A common model used to simulate actual evapotranspiration in watershed scale hydrologic models is the Kristensen and Jensen model (e.g. Mike She or MODHMS models). While the Kristensen and Jensen model was originally developed for Nordic climates, it has been extensively used in other types of environments without specific calibration or testing of its performance in climates other than the one for which the model was developed. In semiarid watershed hydrology, evapotranspiration is the main output component of the mass balance and is critical for a correct description of the hydrologic processes during interstorm periods. In this work we calibrate and study the performance of the Kristensen and Jensen model in a semiarid rangeland environment in southwest Spain. For this, a full soil water atmosphere model was used to describe the water fluxes in a column of soil. The model describes variably saturated water flow in the soil using Richards' equation and the van Genuchten soil retention curves. The Kristensen and Jensen model is used to calculate direct evaporation and the water uptake by grass cover. Seven parameters are simultaneously calibrated. Two are for the van Genuchten retention curve and three for the Kristensen and Jensen model. Hydraulic conductivity is assumed to decay exponentially with depth. The decay exponent and the hydraulic conductivity at zero depth are the two remaining parameters to be calibrated. Given the large set of free parameters involved, the calibration set up involves two sources of information: soil moisture measurements at four different depths in the soil column and an auxiliary simple linear model relating maximum daily temperatures and average soil moisture; and two sources of prior information: field capacity measured on soil cores and the maximum dry weight biomass when the soil is fully covered by grass. A global search method (SCE-UA) is used to locate the global minimum in the allowed parameter error space and a local

  13. 车载激光雷达外参数的标定方法%Extrinsic Calibration Method for Multiple Lidars Mounted on Mobile Vehicle

    Institute of Scientific and Technical Information of China (English)

    程金龙; 冯莹; 曹毓; 雷兵; 魏立安

    2013-01-01

    基于多激光雷达的车载三维重建系统在工作时需要对激光雷达的外参数(包括三个旋转参数和三个平移参数)进行标定。针对激光雷达外参数的标定问题,根据激光雷达扫描点不可见、单线式扫描等工作特点,以基于空间向量的三维坐标系转换模型为基础,提出了一种采用三面靶标的激光雷达外参数标定方法,对靶标进行三维重建,利用随机采样一致性(RANSAC)算法进行平面分割和同名向量的提取,采用坐标系转换模型对标定参数求解,实现了激光雷达外参数的标定,并结合仿真结果以及标定前后多激光雷达系统三维重建结果对方法的有效性及精度进行了评估和验证。%Extrinsic calibration of Lidar is necessary for vehicle-mounted 3D reconstruction system using multiple Lidars. Concerned on the extrinsic calibration of Lidar, as the scanning point of Lidar is invisible and scanning mode is single-lined, according to the 3D frame transforming model based on space vectors, a new calibration method is proposed, in which a trihedron target is adopted. The proposed method, which contains reconstruction of the target, segmentation of plane feature and extraction of corresponding vectors using the Random Sample Consensus (RANSAC) algorithm, solving the extrinsic parameters using the transforming model of 3D frame based on space vectors, was applied to extrinsic calibration of Lidar in a 3D reconstruction system. The effectiveness and precision of the method are proved by simulation and 3D reconstruction importing the calibration results.

  14. 红外单光子探测器定标方法研究%CALIBRATION METHOD STUDY FOR INFRARED SINGLE-PHOTON DETECTORS

    Institute of Scientific and Technical Information of China (English)

    马伊平; 宫铖; 丁漪; 冯瑜

    2015-01-01

    紫外激光器输出的355 nm激光泵浦BBO晶体,采用晶体的I类相位匹配,利用晶体的角度调谐特性得到的红外波段光源应用于单光子探测器定标,提出了利用参量下转换产生的纠缠光子对定标SPCM单光子探测器量子效率的方法,介绍了实验原理和定标装置。%355 nm UV laser output laser pumping BBO crystal, using I phase matching crystal, infrared light source utilizing crystal angle tuning characteristics are applied to the single-photon detector calibration. We propose the use of parametric down conversion produce entangled photons calibrate SPCM quantum efficiency of the method. We also introduce the principle and experiment of calibration device.

  15. Manufacture of first wall mock-ups with calibrated defects for fabrication control methods: Development of UT detectable defects

    International Nuclear Information System (INIS)

    A Research and Development program for the ITER Blanket-First Wall has been implemented in Europe to provide input data for the manufacture of the full-scale production components. In this frame, FW mock-ups have been fabricated according to ITER FW design requirements. In order to define acceptance criteria for non-destructive examination (NDE) for the series production, FW mock-ups (FWMU) representative of ITER FW are manufactured with calibrated defects to be validated by heat flux tests to assess the critical defect dimensions able to degrade fatigue performance and lifetime, when located at Be/CuCrZr joint corners and beryllium tile edges, and at the CuCrZr/CuCrZr and CuCrZr/316L SS joints. In order to create the defects of given dimensions, two techniques were studied: alumina and zirconia coating using a PVD technique in one hand; and on the another hand alumina and quartz thicker inserts. The paper describes the different approaches used to manufacture test samples with calibrated defects, before applying on FW mock-ups, and related non-destructive examination (NDE) by ultrasonic examination (UT). High heat flux (HHF) testing is not part of this work.

  16. 一种新的CCD相机与激光相机的标定方法%A New Calibration Method for CCD Camera and Laser Camera

    Institute of Scientific and Technical Information of China (English)

    桑瑞娟

    2012-01-01

    In the intelligent robot' s navigation and positioning system, in order to get more comprehen- sive and accurate information, people generally use multiple sensors to get information, therefore fuse da- tas are needed, the major problem of the fusion of multiple sensors is the coordinates calibration between them. In consideration of the coordinate calibration between CCD camera and laser camera: firstly, the information of special points in the calibration object ject was built, secondly, the corners were detected plane were removed, finally the rotation matrix and was got, then the pane equation of the calibration ob- by harris method, the points which were not in the translation matrix were solved. The results show that%在智能机器人的导航定位系统中,为了得到的信息更加全面和准确,一般采用多种传感器共同获取信息,这就需要进行数据的融合,多传感器的联合标定是数据融合的关键问题。针对CCD相机和激光相机进行标定,首先采集标定靶特殊点的信息,建立标定靶平面方程,其次用harris角点检测算法检测角点,去除不符合平面方程的点,最后求解旋转矩阵和平移矩阵。实验结果表明,该方法能有效去除混合像素,标定结果更加准确。

  17. Regionalisation of a distributed method for flood quantiles estimation: Revaluation of local calibration hypothesis to enhance the spatial structure of the optimised parameter

    Science.gov (United States)

    Odry, Jean; Arnaud, Patrick

    2016-04-01

    The SHYREG method (Aubert et al., 2014) associates a stochastic rainfall generator and a rainfall-runoff model to produce rainfall and flood quantiles on a 1 km2 mesh covering the whole French territory. The rainfall generator is based on the description of rainy events by descriptive variables following probability distributions and is characterised by a high stability. This stochastic generator is fully regionalised, and the rainfall-runoff transformation is calibrated with a single parameter. Thanks to the stability of the approach, calibration can be performed against only flood quantiles associated with observated frequencies which can be extracted from relatively short time series. The aggregation of SHYREG flood quantiles to the catchment scale is performed using an areal reduction factor technique unique on the whole territory. Past studies demonstrated the accuracy of SHYREG flood quantiles estimation for catchments where flow data are available (Arnaud et al., 2015). Nevertheless, the parameter of the rainfall-runoff model is independently calibrated for each target catchment. As a consequence, this parameter plays a corrective role and compensates approximations and modelling errors which makes difficult to identify its proper spatial pattern. It is an inherent objective of the SHYREG approach to be completely regionalised in order to provide a complete and accurate flood quantiles database throughout France. Consequently, it appears necessary to identify the model configuration in which the calibrated parameter could be regionalised with acceptable performances. The revaluation of some of the method hypothesis is a necessary step before the regionalisation. Especially the inclusion or the modification of the spatial variability of imposed parameters (like production and transfer reservoir size, base flow addition and quantiles aggregation function) should lead to more realistic values of the only calibrated parameter. The objective of the work presented

  18. 一种新的单点标定视线估计方法%A Novel Gaze Estimation Method with One-point Calibration

    Institute of Scientific and Technical Information of China (English)

    熊春水; 黄磊; 刘昌平

    2014-01-01

    To solve the problem that the calibration procedures in most current gaze estimation methods are tedious when only a single camera and single light source are used, we propose a novel gaze estimation method with one-point calibration. In our approach, statistical models of multiple points on the screen are built in advance and an interpolation-based method is used to estimate the point of regard (PoR) of the user on the screen. The main contributions of this paper are: 1) we propose a novel one-point calibration gaze estimation model based on statistical method, which reduces the complexity of the calibration procedure; 2) incremental learning method is used to update the model, which could improve the adaptability of different users and head movements. The experimental results show that the proposed method is effective for different users with different head movements.%在单相机单光源条件下,针对现有视线估计方法标定过程复杂的问题,提出一种新的单点标定视线估计方法。该方法预先建立屏幕中多个点的视线估计统计模型,进而通过插值估计用户在屏幕中的视点。主要创新工作有:1)提出一种基于统计的单点标定视线估计模型,降低了标定过程的复杂度;2)采用增量学习方法进一步更新模型,提高模型对不同用户以及头部运动的适应性。实验证明,本文方法在设备简单、允许头部运动的前提下,只需单点标定就能够取得较高精度。

  19. Binary Classifier Calibration: Non-parametric approach

    OpenAIRE

    Naeini, Mahdi Pakdaman; Cooper, Gregory F.; Hauskrecht, Milos

    2014-01-01

    Accurate calibration of probabilistic predictive models learned is critical for many practical prediction and decision-making tasks. There are two main categories of methods for building calibrated classifiers. One approach is to develop methods for learning probabilistic models that are well-calibrated, ab initio. The other approach is to use some post-processing methods for transforming the output of a classifier to be well calibrated, as for example histogram binning, Platt scaling, and is...

  20. Entropic calibration revisited

    Energy Technology Data Exchange (ETDEWEB)

    Brody, Dorje C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)]. E-mail: d.brody@imperial.ac.uk; Buckley, Ian R.C. [Centre for Quantitative Finance, Imperial College, London SW7 2AZ (United Kingdom); Constantinou, Irene C. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom); Meister, Bernhard K. [Blackett Laboratory, Imperial College, London SW7 2BZ (United Kingdom)

    2005-04-11

    The entropic calibration of the risk-neutral density function is effective in recovering the strike dependence of options, but encounters difficulties in determining the relevant greeks. By use of put-call reversal we apply the entropic method to the time reversed economy, which allows us to obtain the spot price dependence of options and the relevant greeks.