A calculation and uncertainty evaluation method for the effective area of a piston rod used in quasi-static pressure calibration

Science.gov (United States)

Gu, Tingwei; Kong, Deren; Shang, Fei; Chen, Jing

2018-04-01

This paper describes the merits and demerits of different sensors for measuring propellant gas pressure, the applicable range of the frequently used dynamic pressure calibration methods, and the working principle of absolute quasi-static pressure calibration based on the drop-weight device. The main factors affecting the accuracy of pressure calibration are analyzed from two aspects of the force sensor and the piston area. To calculate the effective area of the piston rod and evaluate the uncertainty between the force sensor and the corresponding peak pressure in the absolute quasi-static pressure calibration process, a method for solving these problems based on the least squares principle is proposed. According to the relevant quasi-static pressure calibration experimental data, the least squares fitting model between the peak force and the peak pressure, and the effective area of the piston rod and its measurement uncertainty, are obtained. The fitting model is tested by an additional group of experiments, and the peak pressure obtained by the existing high-precision comparison calibration method is taken as the reference value. The test results show that the peak pressure obtained by the least squares fitting model is closer to the reference value than the one directly calculated by the cross-sectional area of the piston rod. When the peak pressure is higher than 150 MPa, the percentage difference is less than 0.71%, which can meet the requirements of practical application.

Adjustable Pitot Probe

Science.gov (United States)

Ashby, George C., Jr.; Robbins, W. Eugene; Horsley, Lewis A.

1991-01-01

Probe readily positionable in core of uniform flow in hypersonic wind tunnel. Formed of pair of mating cylindrical housings: transducer housing and pitot-tube housing. Pitot tube supported by adjustable wedge fairing attached to top of pitot-tube housing with semicircular foot. Probe adjusted both radially and circumferentially. In addition, pressure-sensing transducer cooled internally by water or other cooling fluid passing through annulus of cooling system.

Calibration of atomic force microscope cantilevers using standard and inverted static methods assisted by FIB-milled spatial markers

International Nuclear Information System (INIS)

Slattery, Ashley D; Blanch, Adam J; Quinton, Jamie S; Gibson, Christopher T

2013-01-01

Static methods to determine the spring constant of AFM cantilevers have been widely used in the scientific community since the importance of such calibration techniques was established nearly 20 years ago. The most commonly used static techniques involve loading a trial cantilever with a known force by pressing it against a pre-calibrated standard or reference cantilever. These reference cantilever methods have a number of sources of uncertainty, which include the uncertainty in the measured spring constant of the standard cantilever, the exact position of the loading point on the reference cantilever and how closely the spring constant of the trial and reference cantilever match. We present a technique that enables users to minimize these uncertainties by creating spatial markers on reference cantilevers using a focused ion beam (FIB). We demonstrate that by combining FIB spatial markers with an inverted reference cantilever method, AFM cantilevers can be accurately calibrated without the tip of the test cantilever contacting a surface. This work also demonstrates that for V-shaped cantilevers it is possible to determine the precise loading position by AFM imaging the section of the cantilever where the two arms join. Removing tip-to-surface contact in both the reference cantilever method and sensitivity calibration is a significant improvement, since this is an important consideration for AFM users that require the imaging tip to remain in pristine condition before commencing measurements. Uncertainties of between 5 and 10% are routinely achievable with these methods. (paper)

Calculation of the Pitot tube correction factor for Newtonian and non-Newtonian fluids.

Science.gov (United States)

Etemad, S Gh; Thibault, J; Hashemabadi, S H

2003-10-01

This paper presents the numerical investigation performed to calculate the correction factor for Pitot tubes. The purely viscous non-Newtonian fluids with the power-law model constitutive equation were considered. It was shown that the power-law index, the Reynolds number, and the distance between the impact and static tubes have a major influence on the Pitot tube correction factor. The problem was solved for a wide range of these parameters. It was shown that employing Bernoulli's equation could lead to large errors, which depend on the magnitude of the kinetic energy and energy friction loss terms. A neural network model was used to correlate the correction factor of a Pitot tube as a function of these three parameters. This correlation is valid for most Newtonian, pseudoplastic, and dilatant fluids at low Reynolds number.

14 CFR 121.342 - Pitot heat indication systems.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Pitot heat indication systems. 121.342... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Instrument and Equipment Requirements § 121.342 Pitot... a flight instrument pitot heating system unless the airplane is also equipped with an operable pitot...

14 CFR 23.1326 - Pitot heat indication systems.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Pitot heat indication systems. 23.1326... Instruments: Installation § 23.1326 Pitot heat indication systems. If a flight instrument pitot heating system... provided to indicate to the flight crew when that pitot heating system is not operating. The indication...

14 CFR 125.206 - Pitot heat indication systems.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Pitot heat indication systems. 125.206... Equipment Requirements § 125.206 Pitot heat indication systems. (a) Except as provided in paragraph (b) of... flight instrument pitot heating system unless the airplane is equipped with an operable pitot heat...

14 CFR 25.1326 - Pitot heat indication systems.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Pitot heat indication systems. 25.1326....1326 Pitot heat indication systems. If a flight instrument pitot heating system is installed, an indication system must be provided to indicate to the flight crew when that pitot heating system is not...

14 CFR 135.158 - Pitot heat indication systems.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Pitot heat indication systems. 135.158... Equipment § 135.158 Pitot heat indication systems. (a) Except as provided in paragraph (b) of this section... instrument pitot heating system unless the airplane is also equipped with an operable pitot heat indication...

Numerical Predictions of Static-Pressure-Error Corrections for a Modified T-38C Aircraft

Science.gov (United States)

2014-12-15

but the more modern work of Latif et al . [11] demonstrated that compensated Pitot-static probes can be simulated accurately for subsonic and...what was originally estimated from CFD simulations in Bhamidipati et al . [3] by extracting the static-pressure error in front of the production probe...Aerodynamically Compensating Pitot Tube,” Journal of Aircraft, Vol. 25, No. 6, 1988, pp. 544–547. doi:10.2514/3.45620 [11] Latif , A., Masud, J., Sheikh, S. R., and

Measurement of mass flux in high temperature high pressure steam-water two-phase flow using a combination of Pitot tubes and a gamma densitometer

International Nuclear Information System (INIS)

Chan, A.M.C.; Bzovey, D.

1990-01-01

The design and calibration of a two-phase mass-flux measurement device making use of a Pitot-tube rake and a gamma densitometer are described. Five Pitot tubes and three chordal void-fraction measurements are used. Similar devices have been reported previously. The present device is designed for easy operation and simple data interpretation for both axisymmetric and non-axisymmetric flows under high pressure transient two-phase flow conditions. The device was calibrated using a vertical two-phase flow loop as well as a model-scale pump loop in horizontal orientation. Good agreement between the measured two-phase mass fluxes and the single-phase values was obtained in both cases. (orig.)

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 ...... response to the desired value. The method is demonstrated mathematically on a typical PLL topology and it is extended to SigmaDelta fractional-N PLLs. A set of simulations performed with two different simulators is used to verify the applicability of the method.......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...

Simulated Pitot tube designed to detect blockage by ice, volcanic dust, sand, insects and to clear it: phase 1

Science.gov (United States)

Jackson, David A.

2014-05-01

A simulated coaxial Pitot tube has been developed using fibre optic sensors combined with actuators to monitor and maintain its correct operation under different environmental conditions. Experiments are reported showing that the dynamic and static tubes can be cleared of ice. It is also demonstrated that the dynamic tube can be cleared of dust and sand which is not the case for the static tube in the coaxial configuration. An approach is proposed to overcome this problem involving a conventional configuration where the static tube is operated independently orthogonal to the dynamic tube with a second set of sensors and actuators.

Pressure prediction model based on artificial neural network optimized by genetic algorithm and its application in quasi-static calibration of piezoelectric high-pressure sensor.

Science.gov (United States)

Gu, Tingwei; Kong, Deren; Jiang, Jian; Shang, Fei; Chen, Jing

2016-12-01

This paper applies back propagation neural network (BPNN) optimized by genetic algorithm (GA) for the prediction of pressure generated by a drop-weight device and the quasi-static calibration of piezoelectric high-pressure sensors for the measurement of propellant powder gas pressure. The method can effectively overcome the slow convergence and local minimum problems of BPNN. Based on test data of quasi-static comparison calibration method, a mathematical model between each parameter of drop-weight device and peak pressure and pulse width was established, through which the practical quasi-static calibration without continuously using expensive reference sensors could be realized. Compared with multiple linear regression method, the GA-BPNN model has higher prediction accuracy and stability. The percentages of prediction error of peak pressure and pulse width are less than 0.7% and 0.3%, respectively.

Pitot-tube turbine as wind power plant

Energy Technology Data Exchange (ETDEWEB)

Naake, L

1978-10-19

The use of the Pitot tube turbine as a wind power station is an application of the well known Pitot tube with the turbines built into jet engines. The novelty of this invention lies in the combined nozzle and turbine unit, where the wind is caught in the funnel opening, is accelerated in the narrow flow zone and then acts on the turbine blades. Due to the acceleration, a greater torque is exerted on the turbine than in free air flow. The Pitot tube turbine consists of a casing with a turbine inside, which is fixed by guide vane supports to the casing and which contains one or two stage turbine blades and electrical generators. The whole structure with the rotor is set on a sub-frame and rotation is contained by control surfaces. The subframe can be used as a building.

Modular Rake of Pitot Probes

Science.gov (United States)

Dunlap, Timothy A.; Henry, Michael W.; Homyk, Raymond P.

2004-01-01

The figure presents selected views of a modular rake of 17 pitot probes for measuring both transient and steady-state pressures in a supersonic wind tunnel. In addition to pitot tubes visible in the figure, the probe modules contain (1) high-frequency dynamic-pressure transducers connected through wires to remote monitoring circuitry and (2) flow passages that lead to tubes that, in turn, lead to remote steady-state pressure transducers. Prior pitot-probe rakes were fabricated as unitary structures, into which the individual pitot probes were brazed. Repair or replacement of individual probes was difficult, costly, and time-consuming because (1) it was necessary to remove entire rakes in order to unbraze individual malfunctioning probes and (2) the heat of unbrazing a failed probe and of brazing a new probe in place could damage adjacent probes. In contrast, the modules in the present probe are designed to be relatively quickly and easily replaceable with no heating and, in many cases, without need for removal of the entire rake from the wind tunnel. To remove a malfunctioning probe, one first removes a screw-mounted V-cross-section cover that holds the probe and adjacent probes in place. Then one removes a screw-mounted cover plate to gain access to the steady-state pressure tubes and dynamicpressure wires. Next, one disconnects the tube and wires of the affected probe. Finally, one installs a new probe in the reverse of the aforementioned sequence. The wire connections can be made by soldering, but to facilitate removal and installation, they can be made via miniature plugs and sockets. The connections between the probe flow passages and the tubes leading to the remote pressure sensors can be made by use of any of a variety of readily available flexible tubes that can be easily pulled off and slid back on for removal and installation, respectively.

Calibrating airborne measurements of airspeed, pressure and temperature using a Doppler laser air-motion sensor

Directory of Open Access Journals (Sweden)

W. A. Cooper

2014-09-01

Full Text Available A new laser air-motion sensor measures the true airspeed with a standard uncertainty of less than 0.1 m s−1 and so reduces uncertainty in the measured component of the relative wind along the longitudinal axis of the aircraft to about the same level. The calculated pressure expected from that airspeed at the inlet of a pitot tube then provides a basis for calibrating the measurements of dynamic and static pressure, reducing standard uncertainty in those measurements to less than 0.3 hPa and the precision applicable to steady flight conditions to about 0.1 hPa. These improved measurements of pressure, combined with high-resolution measurements of geometric altitude from the global positioning system, then indicate (via integrations of the hydrostatic equation during climbs and descents that the offset and uncertainty in temperature measurement for one research aircraft are +0.3 ± 0.3 °C. For airspeed, pressure and temperature, these are significant reductions in uncertainty vs. those obtained from calibrations using standard techniques. Finally, it is shown that although the initial calibration of the measured static and dynamic pressures requires a measured temperature, once calibrated these measured pressures and the measurement of airspeed from the new laser air-motion sensor provide a measurement of temperature that does not depend on any other temperature sensor.

Pengembangan Pipa Pitot Sebagai Peraga Pembelajaran Mekanika Fluida

OpenAIRE

Suryadi, Anang; Suyatna, Agus; Suyanto, Eko

2013-01-01

Pitot Pipe teaching media for measure fluid speed was not available at SMAN Way Lima. To complete the purpose of fluid mechanic teaching media, pitot pipe teaching media was develop and provide guide book for teaching fluid concept. Teaching media and guide book development were using Suyanto procedure and combine with BSNP (2006). The procedure that consist of purpose analyse, resource identification, product spesific indentification, product developing, product testing and production. Those...

Spectral Characteristics of Pitot Noise

Science.gov (United States)

Hornung, H. G.; Parziale, N. J.

For experimental studies of transition from laminar to turbulent boundary layer flow it is important to know the ambient noise spectrum in the facility. In supersonic wind tunnels this is often assessed by measuring pitot pressure noise.

Calibration techniques for the hot wire anemometer in a low velocity region

International Nuclear Information System (INIS)

Fujimura, Kaoru; Kawamura, Hiroshi

1980-03-01

In connection with experiments on coolant flow in the core of multi-purpose VHTR, a low-velocity calibration wind tunnel was made, and techniques for the hot wire anemometer in the air were investigated. Following are the results. 1) A technique using the frequency of von Karman vortex street is not recommended because of the irregular mode in a low velocity region. 2) A Pitot tube is valid only for the flow velocities larger than 1 m/s. 3) The thermal trace technique is suitable in a relatively wide range of velocity, if velocity defect in the wake is compensated for. When flow velocity is larger than 1 m/s, the thermal trace technique is consistent with the Pitot tube method. (author)

Numerical and experimental research on pentagonal cross-section of the averaging Pitot tube

Science.gov (United States)

Zhang, Jili; Li, Wei; Liang, Ruobing; Zhao, Tianyi; Liu, Yacheng; Liu, Mingsheng

2017-07-01

Averaging Pitot tubes have been widely used in many fields because of their simple structure and stable performance. This paper introduces a new shape of the cross-section of an averaging Pitot tube. Firstly, the structure of the averaging Pitot tube and the distribution of pressure taps are given. Then, a mathematical model of the airflow around it is formulated. After that, a series of numerical simulations are carried out to optimize the geometry of the tube. The distribution of the streamline and pressures around the tube are given. To test its performance, a test platform was constructed in accordance with the relevant national standards and is described in this paper. Curves are provided, linking the values of flow coefficient with the values of Reynolds number. With a maximum deviation of only  ±3%, the results of the flow coefficient obtained from the numerical simulations were in agreement with those obtained from experimental methods. The proposed tube has a stable flow coefficient and favorable metrological characteristics.

Effect of the collector tube profile on Pitot pump performances

Science.gov (United States)

Komaki, K.; Kanemoto, T.; Sagara, K.; Umekage, T.

2013-12-01

The pitot pump is composed of the rotating casing with the impeller channel and the pitot tube type collector as the discharge line. The radial impeller feeds water to the rotating casing. The water rotating together with the casing is caught by the stationary pitot tube type collector, and then discharges to the outside. This type pump, as the extra high head pump, is provided mainly for boiler feed systems, and has been designed by trial and error. To optimize the pump profiles, it is desirable to investigate not only performances but also internal flow conditions. This paper discusses experimentally and numerically the relation between the pump performances and the flow conditions in the rotating casing. The moderately larger dimensions of the collector make the pump head and the discharge high with the higher hydraulic efficiency. The flow in the casing is almost the forced vortex type whose velocity is in proportion to the radius but the core velocity is affected with the drag force of the stationary collector. Based upon the above results, the profile of the pitot tube type collector was optimized with the numerical simulation.

Effect of the collector tube profile on Pitot pump performances

International Nuclear Information System (INIS)

Komaki, K; Sagara, K; Kanemoto, T; Umekage, T

2013-01-01

The pitot pump is composed of the rotating casing with the impeller channel and the pitot tube type collector as the discharge line. The radial impeller feeds water to the rotating casing. The water rotating together with the casing is caught by the stationary pitot tube type collector, and then discharges to the outside. This type pump, as the extra high head pump, is provided mainly for boiler feed systems, and has been designed by trial and error. To optimize the pump profiles, it is desirable to investigate not only performances but also internal flow conditions. This paper discusses experimentally and numerically the relation between the pump performances and the flow conditions in the rotating casing. The moderately larger dimensions of the collector make the pump head and the discharge high with the higher hydraulic efficiency. The flow in the casing is almost the forced vortex type whose velocity is in proportion to the radius but the core velocity is affected with the drag force of the stationary collector. Based upon the above results, the profile of the pitot tube type collector was optimized with the numerical simulation

Calibration of nozzle for air mass flow measurement

Science.gov (United States)

Uher, Jan; Kanta, Lukáš

2017-09-01

The effort to make calibration measurement of mass flow through a nozzle was not satisfying. Traversing across the pipe radius with Pitot probe was done. The presence of overshoot behind the bend in the pipe was found. The overshoot led to an asymmetric velocity profile.

Numerical and experimental research on pentagonal cross-section of the averaging Pitot tube

International Nuclear Information System (INIS)

Zhang, Jili; Li, Wei; Liang, Ruobing; Zhao, Tianyi; Liu, Yacheng; Liu, Mingsheng

2017-01-01

Averaging Pitot tubes have been widely used in many fields because of their simple structure and stable performance. This paper introduces a new shape of the cross-section of an averaging Pitot tube. Firstly, the structure of the averaging Pitot tube and the distribution of pressure taps are given. Then, a mathematical model of the airflow around it is formulated. After that, a series of numerical simulations are carried out to optimize the geometry of the tube. The distribution of the streamline and pressures around the tube are given. To test its performance, a test platform was constructed in accordance with the relevant national standards and is described in this paper. Curves are provided, linking the values of flow coefficient with the values of Reynolds number. With a maximum deviation of only  ±3%, the results of the flow coefficient obtained from the numerical simulations were in agreement with those obtained from experimental methods. The proposed tube has a stable flow coefficient and favorable metrological characteristics. (paper)

Development and calibration of instruments for measurements in transient two-phase flow

International Nuclear Information System (INIS)

Banerjee, S.; Heidrick, T.R.

1981-01-01

For validation and development of theoretical models for transient two-phase flow, it is necessary to measure local and cross-sectionally averaged thermalhydraulic parameters. Of these parameters, void fraction and mass velocity are the most difficult to measure. In this paper, we present our recent work on various techniques for determining these quantities. The possibility of determining flow regime by using fast neutron transmission is discussed. The development of a miniaturized electrical resistivity probe for measuring local void fraction is described, together with calibrations obtained by integrating the void fraction profile and comparing the cross-sectionally averaged void fraction with direct measurements using two quick closing valves. Results on the calibration of combinations of full-flow turbine meters, Pitot tube rakes and gamma densitometers for measuring cross-sectionally averaged mass velocity in steady steam-water flow are presented. The results are interpreted with a simple model using single-phase calibration factors for the Pitot tube rakes and turbine meters. Calibration experiments were also done in transient steam-water flows and interpretation of the results with the steady state models is also discussed

Multi-gate Pitot tube for the measurement of water flow in cooling systems; Tubo de Pitot multi-puertos para la medicion de flujo de agua en sistemas de enfriamiento

Energy Technology Data Exchange (ETDEWEB)

Figueroa Ibarra, Luis; Rodriguez Martinez, Jose Hugo; Santabarbara Botello, Marcelino [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

2007-07-01

In this article the design of a novel measuring device of water flowing in large diameter pipes is described. A description is made of the instrument commonly used at present for this purpose (simple Pitot tube), whose design is based on the Standard CTI Code ATC-105 published by the Cooling Tower Institute (CTI ATC-105, 2000). The disadvantages of the simple Pitot tube in comparison with the new proposed device are emphasized (Multi-gate Pitot tube), of which its construction and design is described in detail. In the present article are also shown the results obtained of the circulation water flow measurements, performed in the cooling system of a fossil fuel power plant. These results are compared with the results of flow measurement obtained by means of the simulation of the thermodynamic cycle of the power station, using commercial software. [Spanish] En este articulo se describe el diseno de un novedoso medidor de flujo de agua que circula en tuberias de gran diametro. Se hace una descripcion del instrumento comunmente usado en la actualidad para dicho proposito (tubo de Pitot simple), cuyo diseno se basa en el estandar CTI Code ATC-105 publicado por el Cooling Tower Institute (CTI ATC-105, 2000). Se puntualizan las desventajas del tubo de Pitot simple en comparacion con el nuevo dispositivo propuesto (tubo de Pitot Multi-puertos), del cual se describe detalladamente su construccion y diseno. En el presente articulo tambien se muestran los resultados obtenidos de las mediciones de flujo de agua de circulacion, realizadas en el sistema de enfriamiento de una central termoelectrica. Dichos resultados son comparados con los resultados de flujo obtenidos mediante simulacion del ciclo termodinamico de la central, usando un software comercial.

75 FR 7593 - Recent Postings of Broadly Applicable Alternative Test Methods

Science.gov (United States)

2010-02-22

... quality Isokinetic Method. Pollutants for assurance; Prepare Hazardous Waste calibration standards... flow meter of Stack Gas Velocity 60.18(f)(4). in lieu of Method 2. and Volumetric Flow Rate (Type S Pitot Tube). ALT-055 Method 2A--Direct Flares subject to Use a mass flow meter Measurement of Gas 60.18...

Semiempirical method of determining flow coefficients for pitot rake mass flow rate measurements

Science.gov (United States)

Trefny, C. J.

1985-01-01

Flow coefficients applicable to area-weighted pitot rake mass flow rate measurements are presented for fully developed, turbulent flow in an annulus. A turbulent velocity profile is generated semiempirically for a given annulus hub-to-tip radius ratio and integrated numerically to determine the ideal mass flow rate. The calculated velocities at each probe location are then summed, and the flow rate as indicated by the rake is obtained. The flow coefficient to be used with the particular rake geometry is subsequently obtained by dividing the ideal flow rate by the rake-indicated flow rate. Flow coefficients ranged from 0.903 for one probe placed at a radius dividing two equal areas to 0.984 for a 10-probe area-weighted rake. Flow coefficients were not a strong function of annulus hub-to-tip radius ratio for rakes with three or more probes. The semiempirical method used to generate the turbulent velocity profiles is described in detail.

Concept of a Pitot tube able to detect blockage by ice, volcanic ash, sand and insects, and to clear the tube

Science.gov (United States)

Jackson, David A.

2015-12-01

A conceptual coaxial Pitot tube (PT) has been developed using fiber optic sensors combined with actuators to monitor and maintain its correct operation under different environmental conditions. Experiments were performed showing that the dynamic and static tubes can be cleared of ice. It was also demonstrated that the dynamic tube could be cleared of dust and sand which was not the case for the static tube in the coaxial configuration. An approach was proposed to overcome this problem involving a conventional configuration where the static tube was operated independently orthogonal to the dynamic tube, and a second set of sensors and actuators was used. Sensors and associated actuators were developed for temperature and intensity for a linear PT. The aim of this work is to propose a solution for a problem that has caused the loss of the lives of many passengers and crew of aircraft. Resources were not available to test a full implementation of a PT incorporating the proposed modifications.

Response of small pitot tubes in gas-liquid flows

International Nuclear Information System (INIS)

Davis, M.R.

1980-01-01

The pressure rise experienced by a pitot tube immersed in a bubbly gas-liquid mixture flow exceeds that predicted by homogeneous flow analysis under conditions where the pitot is smaller than the mean bubble size. A systematic dependence of the deviation from homogeneous flow analysis exists, depending upon the mixture void fraction. A maximum effect is observed at a void fraction of 0.60, where the pressure rise was found to be 1.73 times the predicted stagnation pressure rise or 0.87 of the mixture momentum flux density. The magnitude of these effects is comparable with similar effects reported elsewhere for gas/solid mixture flow due to relative motion between phases in the vicinity of the sensing probe tip. (orig.)

Experimental and clinical trial of measuring urinary velocity with the pitot tube and a transrectal ultrasound guided video urodynamic system.

Science.gov (United States)

Tsujimoto, Yukio; Nose, Yorihito; Ohba, Kenkichi

2003-01-01

The pitot tube is a common device to measure flow velocity. If the pitot tube is used as an urodynamic catheter, urinary velocity and urethral pressure may be measured simultaneously. However, to our knowledge, urodynamic studies with the pitot tube have not been reported. We experimentally and clinically evaluated the feasibility of the pitot tube to measure urinary velocity with a transrectal ultrasound guided video urodynamic system. We carried out a basal experiment measuring flow velocity in model urethras of 4.5-8.0 mm in inner diameter with a 12-Fr pitot tube. In a clinical trial, 79 patients underwent transrectal ultrasound guided video urodynamic studies with the 12-Fr pitot tube. Urinary velocity was calculated from dynamic pressure (Pd) with the pitot tube formula and the correcting equation according to the results of the basal experiment. Velocity measured by the pitot tube was proportional to the average velocity in model urethras and the coefficients were determined by diameters of model urethras. We obtained a formula to calculate urinary velocity from the basal experiment. The urinary velocity could be obtained in 32 of 79 patients. Qmax was 8.1 +/- 4.3 mL/s (mean +/- SD; range, 18.4-1.3 mL/s), urethral diameter was 7.3 +/- 3.0 mm (mean +/- SD; range, 18.7-4.3 mm) and urinary velocity was 69.4 +/- 43.6 (mean +/- SD; range, 181.3-0 cm/s) at maximum flow rate. The correlation coefficient of Qmax measured by a flowmeter versus Qdv flow rate calculated with urethral diameter and velocity was 0.41 without significant difference. The use of the pitot tube as an urodynamic catheter to a transrectal ultrasound-guided video urodynamic system can measure urethral pressure, diameter and urinary velocity simultaneously. However, a thinner pitot tube and further clinical trials are needed to obtain more accurate results.

In vitro validation of a Pitot-based flow meter for the measurement of respiratory volume and flow in large animal anaesthesia.

Science.gov (United States)

Moens, Yves P S; Gootjes, Peter; Ionita, Jean-Claude; Heinonen, Erkki; Schatzmann, Urs

2009-05-01

To remodel and validate commercially available monitors and their Pitot tube-based flow sensors for use in large animals, using in vitro techniques. Prospective, in vitro experiment. Both the original and the remodelled sensor were studied with a reference flow generator. Measurements were taken of the static flow-pressure relationship and linearity of the flow signal. Sensor airway resistance was calculated. Following recalibration of the host monitor, volumes ranging from 1 to 7 L were generated by a calibration syringe, and bias and precision of spirometric volume was determined. Where manual recalibration was not available, a conversion factor for volume measurement was determined. The influence of gas composition mixture and peak flow on the conversion factor was studied. Both the original and the remodelled sensor showed similar static flow-pressure relationships and linearity of the flow signal. Mean bias (%) of displayed values compared with the reference volume of 3, 5 and 7 L varied between -0.4% and +2.4%, and this was significantly smaller than that for 1 L (4.8% to +5.0%). Conversion factors for 3, 5 and 7 L were very similar (mean 6.00 +/- 0.2, range 5.91-6.06) and were not significantly influenced by the gas mixture used. Increasing peak flow caused a small decrease in the conversion factor. Volume measurement error and conversion factors for inspiration and expiration were close to identity. The combination of the host monitor with the remodelled flow sensor allowed accurate in vitro measurement of flows and volumes in a range expected during large animal anaesthesia. This combination has potential as a reliable spirometric monitor for use during large animal anaesthesia.

78 FR 14640 - Airworthiness Directives; Cessna Aircraft Company Airplanes

Science.gov (United States)

2013-03-07

... AD requires inspecting certain logic modules to determine if certain cabin altitude/pitot static... resetting the pitot switch in the event of pitot heater failure and for total loss of airspeed indication... proposed to require inspecting certain logic modules to determine if certain cabin altitude/pitot static...

Applications of Pitot-meter techniques in two-phase, steam/water, flow

International Nuclear Information System (INIS)

Kastner, W.; Manzano-Ruiz, J.J.

1985-01-01

A simple technique, based on the interpretation of dynamic-pressure readings obtained with local and averaging Pitot-meters (APM) in tow-phase flow, is described and analyzed. The mean dynamic-pressure measurements obtained with an APM allow the calculation of the mass flux of the mixture if the steam quality is known and a combination of two slip-factor correlations is used. The local dynamic-pressure measurements with a multiple Pitot-probe technique provide information on the transition between the most commonly found flow patterns in horizontal piping, i.e. stratified, annular and annular-mist flow

A Comparison of Flight-test Results on a Scout-Bomber Airplane with 4.7 deg and with 10 deg Dihedral in the Wing Outer Panels

Science.gov (United States)

1947-08-01

Calibrated airspeed as used herein is the remling that would.be .. given ly a standsrd Army-Navy airppeed meter ~ou”cted to,a pitot -. .4 static system...Anon.: Specification for Stabillty and Control Characteristics of Airpl=es.SR-l19A, Bur. Aero., April 7, 1$?45. _~--- 4. Pearson, Henry A., and Jones

77 FR 67559 - Airworthiness Directives; Bombardier, Inc. Airplanes

Science.gov (United States)

2012-11-13

... requires replacing certain water accumulator assemblies having a certain part installed on the pitot and... issuing this AD to prevent pitot-static tubing from becoming partially or completely blocked by water... between the pilot and co-pilot's airspeed indicators. We are issuing this AD prevent pitot-static tubing...

Factors Influencing Pitot Probe Centerline Displacement in a Turbulent Supersonic Boundary Layer

Science.gov (United States)

Grosser, Wendy I.

1997-01-01

When a total pressure probe is used for measuring flows with transverse total pressure gradients, a displacement of the effective center of the probe is observed (designated Delta). While this phenomenon is well documented in incompressible flow and supersonic laminar flow, there is insufficient information concerning supersonic turbulent flow. In this study, three NASA Lewis Research Center Supersonic Wind Tunnels (SWT's) were used to investigate pitot probe centerline displacement in supersonic turbulent boundary layers. The relationship between test conditions and pitot probe centerline displacement error was to be determined. For this investigation, ten circular probes with diameter-to-boundary layer ratios (D/delta) ranging from 0.015 to 0.256 were tested in the 10 ft x 10 ft SWT, the 15 cm x 15 cm SWT, and the 1 ft x 1 ft SWT. Reynolds numbers of 4.27 x 10(exp 6)/m, 6.00 x 10(exp 6)/in, 10.33 x 10(exp 6)/in, and 16.9 x 10(exp 6)/m were tested at nominal Mach numbers of 2.0 and 2.5. Boundary layer thicknesses for the three tunnels were approximately 200 mm, 13 mm, and 30 mm, respectively. Initial results indicate that boundary layer thickness, delta, and probe diameter, D/delta play a minimal role in pitot probe centerline offset error, Delta/D. It appears that the Mach gradient, dM/dy, is an important factor, though the exact relationship has not yet been determined. More data is needed to fill the map before a conclusion can be drawn with any certainty. This research provides valuable supersonic, turbulent boundary layer data from three supersonic wind tunnels with three very different boundary layers. It will prove a valuable stepping stone for future research into the factors influencing pitot probe centerline offset error.

Diagnosis of UAV Pitot Tube Defects Using Statistical Change Detection

DEFF Research Database (Denmark)

Hansen, Søren; Blanke, Mogens; Adrian, Jens

2010-01-01

Unmanned Aerial Vehicles need a large degree of tolerance to faults. One of the most important steps towards this is the ability to detect and isolate faults in sensors and actuators in real time and make remedial actions to avoid that faults develop to failure. This paper analyses the possibilit......Unmanned Aerial Vehicles need a large degree of tolerance to faults. One of the most important steps towards this is the ability to detect and isolate faults in sensors and actuators in real time and make remedial actions to avoid that faults develop to failure. This paper analyses...... the possibilities of detecting faults in the pitot tube of a small unmanned aerial vehicle, a fault that easily causes a crash if not diagnosed and handled in time. Using as redundant information the velocity measured from an onboard GPS receiver, the air-speed estimated from engine throttle and the pitot tube...

78 FR 55660 - Airworthiness Directives; Bombardier, Inc. Airplanes

Science.gov (United States)

2013-09-11

... 2 pitot static (PS) probe heater circuit, a number 2 PS probe heater failure may not be detected by... voltage of the number 2 pitot static (PS) probe heater. Since the drain mast heaters are connected in... mast heaters. This same logic circuit is also used to control the line voltage of the number 2 pitot...

Inflight and Preflight Detection of Pitot Tube Anomalies

Science.gov (United States)

Mitchell, Darrell W.

2014-01-01

The health and integrity of aircraft sensors play a critical role in aviation safety. Inaccurate or false readings from these sensors can lead to improper decision making, resulting in serious and sometimes fatal consequences. This project demonstrated the feasibility of using advanced data analysis techniques to identify anomalies in Pitot tubes resulting from blockage such as icing, moisture, or foreign objects. The core technology used in this project is referred to as noise analysis because it relates sensors' response time to the dynamic component (noise) found in the signal of these same sensors. This analysis technique has used existing electrical signals of Pitot tube sensors that result from measured processes during inflight conditions and/or induced signals in preflight conditions to detect anomalies in the sensor readings. Analysis and Measurement Services Corporation (AMS Corp.) has routinely used this technology to determine the health of pressure transmitters in nuclear power plants. The application of this technology for the detection of aircraft anomalies is innovative. Instead of determining the health of process monitoring at a steady-state condition, this technology will be used to quickly inform the pilot when an air-speed indication becomes faulty under any flight condition as well as during preflight preparation.

Miniaturized compact water-cooled pitot-pressure probe for flow-field surveys in hypersonic wind tunnels

Science.gov (United States)

Ashby, George C.

1988-01-01

An experimental investigation of the design of pitot probes for flowfield surveys in hypersonic wind tunnels is reported. The results show that a pitot-pressure probe can be miniaturized for minimum interference effects by locating the transducer in the probe support body and water-cooling it so that the pressure-settling time and transducer temperature are compatible with hypersonic tunnel operation and flow conditions. Flowfield surveys around a two-to-one elliptical cone model in a 20-inch Mach 6 wind tunnel using such a probe show that probe interference effects are essentially eliminated.

COMPARISON OF METHODS FOR GEOMETRIC CAMERA CALIBRATION

Directory of Open Access Journals (Sweden)

J. Hieronymus

2012-09-01

Full Text Available Methods for geometric calibration of cameras in close-range photogrammetry are established and well investigated. The most common one is based on test-fields with well-known pattern, which are observed from different directions. The parameters of a distortion model are calculated using bundle-block-adjustment-algorithms. This methods works well for short focal lengths, but is essentially more problematic to use with large focal lengths. Those would require very large test-fields and surrounding space. To overcome this problem, there is another common method for calibration used in remote sensing. It employs measurements using collimator and a goniometer. A third calibration method uses diffractive optical elements (DOE to project holograms of well known pattern. In this paper these three calibration methods are compared empirically, especially in terms of accuracy. A camera has been calibrated with those methods mentioned above. All methods provide a set of distortion correction parameters as used by the photogrammetric software Australis. The resulting parameter values are very similar for all investigated methods. The three sets of distortion parameters are crosscompared against all three calibration methods. This is achieved by inserting the gained distortion parameters as fixed input into the calibration algorithms and only adjusting the exterior orientation. The RMS (root mean square of the remaining image coordinate residuals are taken as a measure of distortion correction quality. There are differences resulting from the different calibration methods. Nevertheless the measure is small for every comparison, which means that all three calibration methods can be used for accurate geometric calibration.

Comparison of infusion pumps calibration methods

Science.gov (United States)

Batista, Elsa; Godinho, Isabel; do Céu Ferreira, Maria; Furtado, Andreia; Lucas, Peter; Silva, Claudia

2017-12-01

Nowadays, several types of infusion pump are commonly used for drug delivery, such as syringe pumps and peristaltic pumps. These instruments present different measuring features and capacities according to their use and therapeutic application. In order to ensure the metrological traceability of these flow and volume measuring equipment, it is necessary to use suitable calibration methods and standards. Two different calibration methods can be used to determine the flow error of infusion pumps. One is the gravimetric method, considered as a primary method, commonly used by National Metrology Institutes. The other calibration method, a secondary method, relies on an infusion device analyser (IDA) and is typically used by hospital maintenance offices. The suitability of the IDA calibration method was assessed by testing several infusion instruments at different flow rates using the gravimetric method. In addition, a measurement comparison between Portuguese Accredited Laboratories and hospital maintenance offices was performed under the coordination of the Portuguese Institute for Quality, the National Metrology Institute. The obtained results were directly related to the used calibration method and are presented in this paper. This work has been developed in the framework of the EURAMET projects EMRP MeDD and EMPIR 15SIP03.

A Miniature Four-Hole Probe for Measurement of Three-Dimensional Flow with Large Gradients

Directory of Open Access Journals (Sweden)

Ravirai Jangir

2014-01-01

Full Text Available A miniature four-hole probe with a sensing area of 1.284 mm2 to minimise the measurement errors due to the large pressure and velocity gradients that occur in highly three-dimensional turbomachinery flows is designed, fabricated, calibrated, and validated. The probe has good spatial resolution in two directions, thus minimising spatial and flow gradient errors. The probe is calibrated in an open jet calibration tunnel at a velocity of 50 m/s in yaw and pitch angles range of ±40 degrees with an interval of 5 degrees. The calibration coefficients are defined, determined, and presented. Sensitivity coefficients are also calculated and presented. A lookup table method is used to determine the four unknown quantities, namely, total and static pressures and flow angles. The maximum absolute errors in yaw and pitch angles are 2.4 and 1.3 deg., respectively. The maximum absolute errors in total, static, and dynamic pressures are 3.4, 3.9, and 4.9% of the dynamic pressures, respectively. Measurements made with this probe, a conventional five-hole probe and a miniature Pitot probe across a calibration section, demonstrated that the errors due to gradient and surface proximity for this probe are considerably reduced compared to the five-hole probe.

Comparison of pitot traverses taken at varying distances downstream of obstructions.

Science.gov (United States)

Guffey, S E; Booth, D W

1999-01-01

This study determined the deviations between pitot traverses taken under "ideal" conditions--at least seven duct diameter's lengths (i.e., distance = 7D) from obstructions, elbows, junction fittings, and other disturbances to flows--with those taken downstream from commonplace disturbances. Two perpendicular 10-point, log-linear velocity pressure traverses were taken at various distances downstream of tested upstream conditions. Upstream conditions included a plain duct opening, a junction fitting, a single 90 degrees elbow, and two elbows rotated 90 degrees from each other into two orthogonal planes. Airflows determined from those values were compared with the values measured more than 40D downstream of the same obstructions under ideal conditions. The ideal measurements were taken on three traverse diameters in the same plane separated by 120 degrees in honed drawn-over-mandrel tubing. In all cases the pitot tubes were held in place by devices that effectively eliminated alignment errors and insertion depth errors. Duct velocities ranged from 1500 to 4500 ft/min. Results were surprisingly good if one employed two perpendicular traverses. When the averages of two perpendicular traverses was taken, deviations from ideal value were 6% or less even for traverses taken as close as 2D distance from the upstream disturbances. At 3D distance, deviations seldom exceeded 5%. With single diameter traverses, errors seldom exceeded 5% at 6D or more downstream from the disturbance. Interestingly, percentage deviations were about the same at high and low velocities. This study demonstrated that two perpendicular pitot traverses can be taken as close as 3D from these disturbances with acceptable (< or = 5%) deviations from measurements taken under ideal conditions.

Development of a commercially viable piezoelectric force sensor system for static force measurement

Science.gov (United States)

Liu, Jun; Luo, Xinwei; Liu, Jingcheng; Li, Min; Qin, Lan

2017-09-01

A compensation method for measuring static force with a commercial piezoelectric force sensor is proposed to disprove the theory that piezoelectric sensors and generators can only operate under dynamic force. After studying the model of the piezoelectric force sensor measurement system, the principle of static force measurement using a piezoelectric material or piezoelectric force sensor is analyzed. Then, the distribution law of the decay time constant of the measurement system and the variation law of the measurement system’s output are studied, and a compensation method based on the time interval threshold Δ t and attenuation threshold Δ {{u}th} is proposed. By calibrating the system and considering the influences of the environment and the hardware, a suitable Δ {{u}th} value is determined, and the system’s output attenuation is compensated based on the Δ {{u}th} value to realize the measurement. Finally, a static force measurement system with a piezoelectric force sensor is developed based on the compensation method. The experimental results confirm the successful development of a simple compensation method for static force measurement with a commercial piezoelectric force sensor. In addition, it is established that, contrary to the current perception, a piezoelectric force sensor system can be used to measure static force through further calibration.

Improved quasi-static nodal green's function method

International Nuclear Information System (INIS)

Li Junli; Jing Xingqing; Hu Dapu

1997-01-01

Improved Quasi-Static Green's Function Method (IQS/NGFM) is presented, as an new kinetic method. To solve the three-dimensional transient problem, improved Quasi-Static Method is adopted to deal with the temporal problem, which will increase the time step as long as possible so as to decrease the number of times of space calculation. The time step of IQS/NGFM can be increased to 5∼10 times longer than that of Full Implicit Differential Method. In spatial calculation, the NGFM is used to get the distribution of shape function, and it's spatial mesh can be nearly 20 times larger than that of Definite Differential Method. So the IQS/NGFM is considered as an efficient kinetic method

A quasi-static polynomial nodal method for nuclear reactor analysis

International Nuclear Information System (INIS)

Gehin, J.C.

1992-09-01

Modern nodal methods are currently available which can accurately and efficiently solve the static and transient neutron diffusion equations. Most of the methods, however, are limited to two energy groups for practical application. The objective of this research is the development of a static and transient, multidimensional nodal method which allows more than two energy groups and uses a non-linear iterative method for efficient solution of the nodal equations. For both the static and transient methods, finite-difference equations which are corrected by the use of discontinuity factors are derived. The discontinuity factors are computed from a polynomial nodal method using a non-linear iteration technique. The polynomial nodal method is based upon a quartic approximation and utilizes a quadratic transverse-leakage approximation. The solution of the time-dependent equations is performed by the use of a quasi-static method in which the node-averaged fluxes are factored into shape and amplitude functions. The application of the quasi-static polynomial method to several benchmark problems demonstrates that the accuracy is consistent with that of other nodal methods. The use of the quasi-static method is shown to substantially reduce the computation time over the traditional fully-implicit time-integration method. Problems involving thermal-hydraulic feedback are accurately, and efficiently, solved by performing several reactivity/thermal-hydraulic updates per shape calculation

A quasi-static polynomial nodal method for nuclear reactor analysis

Energy Technology Data Exchange (ETDEWEB)

Gehin, Jess C. [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1992-09-01

Modern nodal methods are currently available which can accurately and efficiently solve the static and transient neutron diffusion equations. Most of the methods, however, are limited to two energy groups for practical application. The objective of this research is the development of a static and transient, multidimensional nodal method which allows more than two energy groups and uses a non-linear iterative method for efficient solution of the nodal equations. For both the static and transient methods, finite-difference equations which are corrected by the use of discontinuity factors are derived. The discontinuity factors are computed from a polynomial nodal method using a non-linear iteration technique. The polynomial nodal method is based upon a quartic approximation and utilizes a quadratic transverse-leakage approximation. The solution of the time-dependent equations is performed by the use of a quasi-static method in which the node-averaged fluxes are factored into shape and amplitude functions. The application of the quasi-static polynomial method to several benchmark problems demonstrates that the accuracy is consistent with that of other nodal methods. The use of the quasi-static method is shown to substantially reduce the computation time over the traditional fully-implicit time-integration method. Problems involving thermal-hydraulic feedback are accurately, and efficiently, solved by performing several reactivity/thermal-hydraulic updates per shape calculation.

Standard practice for torque calibration of testing machines and devices

CERN Document Server

American Society for Testing and Materials. Philadelphia

2009-01-01

1.1 This practice covers procedures and requirements for the calibration of torque for static and quasi-static torque capable testing machines or devices. These may, or may not, have torque indicating systems and include those devices used for the calibration of hand torque tools. Testing machines may be calibrated by one of the three following methods or combination thereof: 1.1.1 Use of standard weights and lever arms. 1.1.2 Use of elastic torque measuring devices. 1.1.3 Use of elastic force measuring devices and lever arms. 1.1.4 Any of the methods require a specific uncertainty of measurement and a traceability derived from national standards of mass and length. 1.2 The procedures of 1.1.1, 1.1.2, and 1.1.3 apply to the calibration of the torque-indicating systems associated with the testing machine, such as a scale, dial, marked or unmarked recorder chart, digital display, etc. In all cases the buyer/owner/user must designate the torque-indicating system(s) to be calibrated and included in the repor...

Test description and preliminary pitot-pressure surveys for Langley Test Technique Demonstrator at Mach 6

Science.gov (United States)

Everhart, Joel L.; Ashby, George C., Jr.; Monta, William J.

1992-01-01

A propulsion/airframe integration experiment conducted in the NASA Langley 20-Inch Mach 6 Tunnel using a 16.8-in.-long version of the Langley Test Technique Demonstrator configuration with simulated scramjet propulsion is described. Schlieren and vapor screen visualization of the nozzle flow field is presented and correlated with pitot-pressure flow-field surveys. The data were obtained at nominal free-stream conditions of Re = 2.8 x 10 exp 6 and a nominal engine total pressure of 100 psia. It is concluded that pitot-pressure surveys coupled to schlieren and vapor-screen photographs, and oil flows have revealed flow features including vortices, free shear layers, and shock waves occurring in the model flow field.

Laser transit anemometer and Pitot probe comparative measurements in a sharp cone boundary layer at Mach 4

Science.gov (United States)

Hunter, W. W., Jr.; Ocheltree, S. L.; Russ, C. E., Jr.

1991-01-01

Laser transit anemometer (LTA) measurements of a 7 degree sharp cone boundary layer were conducted in the Air Force/AEDC Supersonic Tunnel A Mach 4 flow field. These measurements are compared with Pitot probe measurements and tricone theory provided by AEDC staff. Measurements were made both in laminar and turbulent boundary layers of the model. Comparison of LTA measurements with theory showed agreement to better than 1 percent for the laminar boundary layer cases. This level of agreement was obtained after small position corrections, 0.01 to 0.6 mm, were applied to the experimental data sets. Pitot probe data when compared with theory also showed small positioning errors. The Pitot data value was also limited due to probe interference with the flow near the model. The LTA turbulent boundary layer data indicated a power law dependence of 6.3 to 6.9. The LTA data was analyzed in the time (Tau) domain in which it was obtained and in the velocity domain. No significant differences were noted between Tau and velocity domain results except in one turbulent boundary layer case.

Calibration method for ion mobility spectrometer

International Nuclear Information System (INIS)

Vasiliev, Valery

2011-01-01

The new method for the calibration of the ion mobility spectrometer has been developed. This article describes the working principle, advantages and disadvantages of the calibration method operating in the mode of explosives detection. This method is most suitable for use in portable detectors, due to the small weight, small size parameters and low power consumption.

Multiple histogram method and static Monte Carlo sampling

NARCIS (Netherlands)

Inda, M.A.; Frenkel, D.

2004-01-01

We describe an approach to use multiple-histogram methods in combination with static, biased Monte Carlo simulations. To illustrate this, we computed the force-extension curve of an athermal polymer from multiple histograms constructed in a series of static Rosenbluth Monte Carlo simulations. From

Effects of Mach number on pitot-probe displacement in a turbulent boundary layer

Science.gov (United States)

Allen, J. M.

1974-01-01

Experimental pitot-probe-displacement data have been obtained in a turbulent boundary layer at a local free-stream Mach number of 4.63 and unit Reynolds number of 6.46 million meter. The results of this study were compared with lower Mach number results of previous studies. It was found that small probes showed displacement only, whereas the larger probes showed not only displacement but also distortion of the shape of the boundary-layer profile. The distortion pattern occurred lower in the boundary layer at the higher Mach number than at the the lower Mach number. The maximum distortion occurred when the center of the probe was about one probe diameter off the test surface. For probes in the wall contact position, the indicated Mach numbers were, for all probes tested, close to the true profile. Pitot-probe displacement was found to increase significantly with increasing Mach number.

Calibration method of radiation monitoring system at TQNPC

International Nuclear Information System (INIS)

Liu Zhengshan; Zhang Qingli; Liu Jinjin; Miao Yuxing; Geng Lixin; Zhuang Yun; Dong Jianfeng; He Change

2009-04-01

The calibration methods and calibration device for standard monitor of radioactive particulate, iodine, noble gas and so on are not yet set up at home. On consideration of the present situation of the radiation monitoring system at the Third Qinshan Nuclear Power Co. Ltd., we have studied the calibration method of these radiation monitoring instruments used for measuring the waste liquid, particulate, iodine and noble gas produced during the operation of nuclear reactor. Through the check against these instruments during the No. 202 and No. 103 overhaul, we got initially the method of the calibration and obtained the transfer coefficient of calibration when secondary solid sources are used for calibration. Through the testing and calibration, the credibility of the radiation monitoring system is enhanced. And at the same time, the problems existing in the calibration are discussed. (authors)

A calibration method for phoswich detectors

CERN Document Server

Gawlikowicz, W; Schröder, W U

2002-01-01

A new method of particle identification and energy calibration is proposed for phoswich detectors consisting of a fast plastic scintillator optically coupled to a CsI(Tl) crystal. In this method, functional relationships between integrated yields of three properly selected portions of the observed composite light output signal are parameterized in terms of three physical components (overlapping in time) of this signal. Then, a complete set of calibration constants is derived, linking these integrated partial yields to particle atomic numbers (Z) and energies (E). The calibration is based on the correlations between partial yields observed in actual data from the physics or 'production' runs, and energy deposits calculated for detector elements. The method is found suitable for a wide range of incident particle species and energies, largely eliminating the need for costly and time-consuming conventional calibration experiments with a variety of beams, targets, and bombarding energies.

An easily implemented static condensation method for structural sensitivity analysis

Science.gov (United States)

Gangadharan, S. N.; Haftka, R. T.; Nikolaidis, E.

1990-01-01

A black-box approach to static condensation for sensitivity analysis is presented with illustrative examples of a cube and a car structure. The sensitivity of the structural response with respect to joint stiffness parameter is calculated using the direct method, forward-difference, and central-difference schemes. The efficiency of the various methods for identifying joint stiffness parameters from measured static deflections of these structures is compared. The results indicate that the use of static condensation can reduce computation times significantly and the black-box approach is only slightly less efficient than the standard implementation of static condensation. The ease of implementation of the black-box approach recommends it for use with general-purpose finite element codes that do not have a built-in facility for static condensation.

A comparison of disturbance levels measured in hypersonic tunnels using a hot-wire anemometer and a pitot pressure probe.

Science.gov (United States)

Stainback, P. C.; Wagner, R. D.

1972-01-01

Disturbance levels were measured in the test section of a Mach 5 blowdown jet using a constant-current, hot-wire anemometer and a pressure transducer. The disturbance levels, measured by the two instruments and normalized by local mean values, agreed within about 30%, with the pitot data higher than the hot-wire data. The rms disturbance levels measured with the hot-wire anemometer and converted to pitot pressures using a quasi-steady flow analysis, were about two-thirds the levels measured with the pitot probe. The variation of the normalized rms disturbance levels with stagnation pressure indicated that transition occurred in the boundary layer on the nozzle wall and influenced the outputs of the instruments located at the exit of the nozzle when the total pressure was about 35 N/sq cm. Below this pressure the disturbance levels decreased markedly. At higher pressures the disturbances were predominantly aerodynamic noise generated by the turbulent boundary layer on the nozzle wall.

Immune Algorithm Complex Method for Transducer Calibration

Directory of Open Access Journals (Sweden)

YU Jiangming

2014-08-01

Full Text Available As a key link in engineering test tasks, the transducer calibration has significant influence on accuracy and reliability of test results. Because of unknown and complex nonlinear characteristics, conventional method can’t achieve satisfactory accuracy. An Immune algorithm complex modeling approach is proposed, and the simulated studies on the calibration of third multiple output transducers is made respectively by use of the developed complex modeling. The simulated and experimental results show that the Immune algorithm complex modeling approach can improve significantly calibration precision comparison with traditional calibration methods.

Methods for preparation of mixtures of gases in air at the parts-per-billion to parts-per-million concentration range for calibration of monitors

International Nuclear Information System (INIS)

Karpas, Z.; Melloul, S.; Pollevoy, Y.; Matmor, A.

1992-05-01

Static and dynamic methods for generating mixture of gases and vapors in air at the parts-per-billion (ppb) to parts-per-million (ppm) concentration range were surveyed. The dynamic methods include: a dynamic flow and mixing system; injection of samples into large volumes of air; exponential dilution; permeation and diffusion tubes; and generation of the target gas by chemical reaction or electrolysis. The static methods include preparation of mixtures by weighing the components, by volumetric mixing and by partial pressure method. The principles governing the utilization of these methods for the appropriate applications were discussed, and examples in which they were used to calibrate an ion mobility spectrometer (IMS) were given. (authors)

Magnetometer and Gyroscope Calibration Method with Level Rotation

Directory of Open Access Journals (Sweden)

Zongkai Wu

2018-03-01

Full Text Available Micro electro mechanical system (MEMS gyroscopes and magnetometers are usually integrated into a sensor module or chip and widely used in a variety of applications. In existing integrated gyroscope and magnetometer calibration methods, rotation in all possible orientations is a necessary condition for a good calibration result. However, rotation around two or more axes is difficult to attain, as it is limited by the range of movement of vehicles such as cars, ships, or planes. To solve this problem, this paper proposes an integrated magnetometer and gyroscope calibration method with level rotation. The proposed method presents a redefined magnetometer output model using level attitude. New gyroscope and magnetometer calibration models are then deduced. In addition, a simplified cubature Kalman filter (CKF is established to estimate calibration parameters. This method possesses important value for application in actual systems, as it only needs level rotation for real-time calibration of gyroscopes and magnetometers. Theoretical analysis and test results verify the validity and feasibility of this method.

Development of pre-critical excore detector linear subchannel calibration method

International Nuclear Information System (INIS)

Choi, Yoo Sun; Goo, Bon Seung; Cha, Kyun Ho; Lee, Chang Seop; Kim, Yong Hee; Ahn, Chul Soo; Kim, Man Soo

2001-01-01

The improved pre-critical excore detector linear subchannel calibration method has been developed to improve the applicability of pre-critical calibration method. The existing calibration method does not always guarantee the accuracy of pre-critical calibration because the calibration results of the previous cycle are not reflected into the current cycle calibration. The developed method has a desirable feature that calibration error would not be propagated in the following cycles since the calibration data determined in previous cycle is incorporated in the current cycle calibration. The pre-critical excore detector linear calibration is tested for YGN unit 3 and UCN unit 3 to evaluate its characteristics and accuracy

Calibration method for a radwaste assay system

International Nuclear Information System (INIS)

Dulama, C.; Dobrin, R.; Toma, Al.; Paunoiu, C.

2004-01-01

A waste assay system entirely designed and manufactured in the Institute for Nuclear Research is used in radwaste treatment and conditioning stream to ensure compliance with national repository radiological requirements. Usually, waste assay systems are calibrated by using various experimental arrangements including calibration phantoms. The paper presents a comparative study concerning the efficiency calibration performed by shell source method and a semiempirical, computational method based on a Monte Carlo algorithm. (authors)

Review of Calibration Methods for Scheimpflug Camera

Directory of Open Access Journals (Sweden)

Cong Sun

2018-01-01

Full Text Available The Scheimpflug camera offers a wide range of applications in the field of typical close-range photogrammetry, particle image velocity, and digital image correlation due to the fact that the depth-of-view of Scheimpflug camera can be greatly extended according to the Scheimpflug condition. Yet, the conventional calibration methods are not applicable in this case because the assumptions used by classical calibration methodologies are not valid anymore for cameras undergoing Scheimpflug condition. Therefore, various methods have been investigated to solve the problem over the last few years. However, no comprehensive review exists that provides an insight into recent calibration methods of Scheimpflug cameras. This paper presents a survey of recent calibration methods of Scheimpflug cameras with perspective lens, including the general nonparametric imaging model, and analyzes in detail the advantages and drawbacks of the mainstream calibration models with respect to each other. Real data experiments including calibrations, reconstructions, and measurements are performed to assess the performance of the models. The results reveal that the accuracies of the RMM, PLVM, PCIM, and GNIM are basically equal, while the accuracy of GNIM is slightly lower compared with the other three parametric models. Moreover, the experimental results reveal that the parameters of the tangential distortion are likely coupled with the tilt angle of the sensor in Scheimpflug calibration models. The work of this paper lays the foundation of further research of Scheimpflug cameras.

Radiation energy calibrating system and method

International Nuclear Information System (INIS)

Jacobson, A.F.

1980-01-01

A radiation energy calibrating system and method which uses a pair of calibrated detectors for measurements of radiation intensity from x-ray tubes for a non-invasive determination of the electrical characteristics; I.E., the tube potential and/or current

Calibration Methods for Reliability-Based Design Codes

DEFF Research Database (Denmark)

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

2004-01-01

The calibration methods are applied to define the optimal code format according to some target safety levels. The calibration procedure can be seen as a specific optimization process where the control variables are the partial factors of the code. Different methods are available in the literature...

Pitot tube and drag body measurements in transient steam--water flows

International Nuclear Information System (INIS)

Fincke, J.R.; Deason, V.A.; Dacus, M.W.

1979-01-01

The use of full-flow drag devices and rakes of water-cooled Pitot tubes to measure the transient two-phase mass flow during loss-of-coolant experiments in pressurized water reactor (PWR) environments has been developed. Mass flow rate measurements have been obtained in high temperature and pressure environments, similar to PWRs, under transient conditions. Comparisons of the measured time integrated value of mass flow to the known system mass before depressurization are made

Calibration and intercomparison methods of dose calibrators used in nuclear medicine facilities

International Nuclear Information System (INIS)

Costa, Alessandro Martins da

1999-01-01

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)

Pitot-Pressure Measurements in Flow Fields Behind a Rectangular Nozzle with Exhaust Jet for Free-Stream Mach Numbers of 0.00, 0.60, and 1.20

Science.gov (United States)

Putnam, L. E.; Mercer, C. E.

1986-01-01

An investigation has been conducted in the Langley 16-Foot Transonic Tunnel to measure the flow field in and around the jet exhaust from a nonaxisymmetric nozzle configuration. The nozzle had a rectangular exit with a width-to-height ratio of 2.38. Pitot-pressure measurements were made at five longitudinal locations downstream of the nozzle exit. The maximum distance downstream of the exit was about 5 nozzle heights. These measurements were made at free-stream Mach numbers of 0.00, 0.60, and 1.20 with the nozzle operating at a ratio of nozzle total pressure to free-stream static pressure of 4.0. The jet exhaust was simulated with high-pressure air that had an exit total temperature essentially equal to the free-stream total temperature.

Unexplored Indoors method for pyranometers calibration traceable to SI

International Nuclear Information System (INIS)

Castillo-Matadamas, H A; Molina-Vazquez, J C; Quintero-Torres, R

2015-01-01

A method to calibrate pyranometers with direct traceability to the International System of Units (SI) is presented, the method use an electrically calibrated pyroelectric detector (ECPR) as standard and offers numerous advantages over outdoors conventional calibration methods, such as reducing the uncertainty from the reference standard and the final uncertainty of the sensitivity coefficient of the calibrated pyranometer; the measurement uncertainty achieved with this method at normal irradiance is 2.1% for a coverage factor k = 2 and could be reduce if one reduces the uncertainty level of the reference standard

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.

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.

Color calibration and color-managed medical displays: does the calibration method matter?

Science.gov (United States)

Roehrig, Hans; Rehm, Kelly; Silverstein, Louis D.; Dallas, William J.; Fan, Jiahua; Krupinski, Elizabeth A.

2010-02-01

Our laboratory has investigated the efficacy of a suite of color calibration and monitor profiling packages which employ a variety of color measurement sensors. Each of the methods computes gamma correction tables for the red, green and blue color channels of a monitor that attempt to: a) match a desired luminance range and tone reproduction curve; and b) maintain a target neutral point across the range of grey values. All of the methods examined here produce International Color Consortium (ICC) profiles that describe the color rendering capabilities of the monitor after calibration. Color profiles incorporate a transfer matrix that establishes the relationship between RGB driving levels and the International Commission on Illumination (CIE) XYZ (tristimulus) values of the resulting on-screen color; the matrix is developed by displaying color patches of known RGB values on the monitor and measuring the tristimulus values with a sensor. The number and chromatic distribution of color patches varies across methods and is usually not under user control. In this work we examine the effect of employing differing calibration and profiling methods on rendition of color images. A series of color patches encoded in sRGB color space were presented on the monitor using color-management software that utilized the ICC profile produced by each method. The patches were displayed on the calibrated monitor and measured with a Minolta CS200 colorimeter. Differences in intended and achieved luminance and chromaticity were computed using the CIE DE2000 color-difference metric, in which a value of ▵E = 1 is generally considered to be approximately one just noticeable difference (JND) in color. We observed between one and 17 JND's for individual colors, depending on calibration method and target.

A simplified method of power calibration

International Nuclear Information System (INIS)

Jones, M.; Elliott, A.

1974-01-01

The Nuclear Reactor Facility, University of Missouri Rolla, has developed a unique method of power calibration for pool type reactors. Since water is incompressible it can be assumed that a rise in the water level of the pool while operating at power can be attributed to the heat input from the reactor core. Water level changes of a small magnitude are easily detectable. This method has proven to be less costly, less time consuming, and more reproducible than the conventional gold foil calibration, and has proven to be more accurate than a heat balance because several problems with heat flow through the walls and to the atmosphere are automatically compensated for with this method. The accuracy of this means of calibration depends upon the accuracy of the measurement of the water level and can normally be expected to be two to four percent. (author)

A simplified method of power calibration

Energy Technology Data Exchange (ETDEWEB)

Jones, M; Elliott, A [University of Missouri-Rolla (United States)

1974-07-01

The Nuclear Reactor Facility, University of Missouri Rolla, has developed a unique method of power calibration for pool type reactors. Since water is incompressible it can be assumed that a rise in the water level of the pool while operating at power can be attributed to the heat input from the reactor core. Water level changes of a small magnitude are easily detectable. This method has proven to be less costly, less time consuming, and more reproducible than the conventional gold foil calibration, and has proven to be more accurate than a heat balance because several problems with heat flow through the walls and to the atmosphere are automatically compensated for with this method. The accuracy of this means of calibration depends upon the accuracy of the measurement of the water level and can normally be expected to be two to four percent. (author)

Investigation of Shock Diffusers at Mach Number 1.85. 1 - Projecting Single Shock Cones

Science.gov (United States)

1947-06-17

cylindrical simulated combustion chamber was used to vary the outlet area of the flow through the diffuser. The pitot -static rake, located as shown in the...and II. Proc. Roy. Soc. (London), ser. A, vol. 139, no 838, Feb. 1, 1933, pp. 278-311. 5. Wyatt, DeMarquis D., and Hunczak, Henry R.: An...Simulated combustion u chamber A 90° W •—Conical damper S Static-pressure orifice ps pitot -static ""rake’ NATIONAL ADVISORY

(HBCU) Thermal-Electric Propulsion With Magnetoplasmadynamic Acceleration

National Research Council Canada - National Science Library

Tabibi, Bagher

1998-01-01

.... An insitu technique, Pitot tube method, was used to measure the total and static pressures of the core flow of the thermal plume in steady state operation in order to characterize and benchmark...

Implementation of the quasi-static method for neutron transport

International Nuclear Information System (INIS)

Alcaro, Fabio; Dulla, Sandra; Ravetto, Piero; Le Tellier, Romain; Suteau, Christophe

2011-01-01

The study of the dynamic behavior of next generation nuclear reactors is a fundamental aspect for safety and reliability assessments. Despite the growing performances of modern computers, the full solution of the neutron Boltzmann equation in the time domain is still an impracticable task, thus several approximate dynamic models have been proposed for the simulation of nuclear reactor transients; the quasi-static method represents the standard tool currently adopted for the space-time solution of neutron transport problems. All the practical applications of this method that have been proposed contain a major limit, consisting in the use of isotropic quantities, such as scalar fluxes and isotropic external neutron sources, being the only data structures available in most deterministic transport codes. The loss of the angular information produces both inaccuracies in the solution of the kinetic model and the inconsistency of the quasi-static method itself. The present paper is devoted to the implementation of a consistent quasi-static method. The computational platform developed by CEA in Cadarache has been used for the creation of a kinetic package to be coupled with the existing SNATCH solver, a discrete-ordinate multi-dimensional neutron transport solver, employed for the solution of the steady-state Boltzmann equation. The work aims at highlighting the effects of the angular treatment of the neutron flux on the transient analysis, comparing the results with those produced by the previous implementations of the quasi-static method. (author)

Calibration and uncertainty in electromagnetic fields measuring methods

International Nuclear Information System (INIS)

Anglesio, L.; Crotti, G.; Borsero, M.; Vizio, G.

1999-01-01

Calibration and reliability in electromagnetic field measuring methods are assured by calibration of measuring instruments. In this work are illustrated systems for generation of electromagnetic fields at low and high frequency, calibration standard and accuracy [it

Calibration methods for ECE systems with microwave sources

International Nuclear Information System (INIS)

Tubbing, B.J.D.; Kissel, S.E.

1987-01-01

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)

An improved EMD method for modal identification and a combined static-dynamic method for damage detection

Science.gov (United States)

Yang, Jinping; Li, Peizhen; Yang, Youfa; Xu, Dian

2018-04-01

Empirical mode decomposition (EMD) is a highly adaptable signal processing method. However, the EMD approach has certain drawbacks, including distortions from end effects and mode mixing. In the present study, these two problems are addressed using an end extension method based on the support vector regression machine (SVRM) and a modal decomposition method based on the characteristics of the Hilbert transform. The algorithm includes two steps: using the SVRM, the time series data are extended at both endpoints to reduce the end effects, and then, a modified EMD method using the characteristics of the Hilbert transform is performed on the resulting signal to reduce mode mixing. A new combined static-dynamic method for identifying structural damage is presented. This method combines the static and dynamic information in an equilibrium equation that can be solved using the Moore-Penrose generalized matrix inverse. The combination method uses the differences in displacements of the structure with and without damage and variations in the modal force vector. Tests on a four-story, steel-frame structure were conducted to obtain static and dynamic responses of the structure. The modal parameters are identified using data from the dynamic tests and improved EMD method. The new method is shown to be more accurate and effective than the traditional EMD method. Through tests with a shear-type test frame, the higher performance of the proposed static-dynamic damage detection approach, which can detect both single and multiple damage locations and the degree of the damage, is demonstrated. For structures with multiple damage, the combined approach is more effective than either the static or dynamic method. The proposed EMD method and static-dynamic damage detection method offer improved modal identification and damage detection, respectively, in structures.

Calibrating page sized Gafchromic EBT3 films

International Nuclear Information System (INIS)

Crijns, W.; Maes, F.; Heide, U. A. van der; Van den Heuvel, F.

2013-01-01

Purpose: The purpose is the development of a novel calibration method for dosimetry with Gafchromic EBT3 films. The method should be applicable for pretreatment verification of volumetric modulated arc, and intensity modulated radiotherapy. Because the exposed area on film can be large for such treatments, lateral scan errors must be taken into account. The correction for the lateral scan effect is obtained from the calibration data itself. Methods: In this work, the film measurements were modeled using their relative scan values (Transmittance, T). Inside the transmittance domain a linear combination and a parabolic lateral scan correction described the observed transmittance values. The linear combination model, combined a monomer transmittance state (T 0 ) and a polymer transmittance state (T ∞ ) of the film. The dose domain was associated with the observed effects in the transmittance domain through a rational calibration function. On the calibration film only simple static fields were applied and page sized films were used for calibration and measurements (treatment verification). Four different calibration setups were considered and compared with respect to dose estimation accuracy. The first (I) used a calibration table from 32 regions of interest (ROIs) spread on 4 calibration films, the second (II) used 16 ROIs spread on 2 calibration films, the third (III), and fourth (IV) used 8 ROIs spread on a single calibration film. The calibration tables of the setups I, II, and IV contained eight dose levels delivered to different positions on the films, while for setup III only four dose levels were applied. Validation was performed by irradiating film strips with known doses at two different time points over the course of a week. Accuracy of the dose response and the lateral effect correction was estimated using the dose difference and the root mean squared error (RMSE), respectively. Results: A calibration based on two films was the optimal balance between

Analysis of thermal power calibration method

International Nuclear Information System (INIS)

Zagar, T.; Ravnik, M.; Persic, A.

2000-01-01

The methods for determining fuel element burnup have recently become interesting because of activities related to the shipment of highly enriched fuel elements back to the United States for final disposal before 2009. The most common and practical method for determining fuel element burnup in research reactors is reactor calculation. Experience has shown that burnup calculations become complicated and biased with uncertainties if a long period of reactor operation must be reproduced. Besides this, accuracy of calculated burnup is always limited with accuracy of reactor power calibration, since burnup calculation is based on calculated power density distribution, which is usually expressed in terms of power released per fuel element and normalised to the reactor power It is obvious that reactor thermal power calibration is very important for precise fuel element burnup calculation. Calculated fuel element burnup is linearly dependent on the thermal reactor power. The reactor power level may be determined from measured absolute thermal flux distribution across the core in the horizontal and vertical planes. Flux distributions are measured with activation of cadmium covered and bare foils irradiated by the steady reactor power. But it should be realised that this method is time consuming and not accurate. This method is practical only for zero power reactors and is in practice very seldom performed for other reactors (e.g. for TRIGA reactor in Ljubljana absolute thermal flux distribution was not performed since reactor reconstruction in 1991). In case of power reactors and research reactors in which a temperature rise across the core is produced and measured than a heat balance method is the most common and accurate method of determining the power output of the core. The purpose of this paper is to analyse the accuracy of calorimetric reactor power calibration method and to analyse the influence of control rod position on nuclear detector reading for TRIGA reactors

Novel crystal timing calibration method based on total variation

Science.gov (United States)

Yu, Xingjian; Isobe, Takashi; Watanabe, Mitsuo; Liu, Huafeng

2016-11-01

A novel crystal timing calibration method based on total variation (TV), abbreviated as ‘TV merge’, has been developed for a high-resolution positron emission tomography (PET) system. The proposed method was developed for a system with a large number of crystals, it can provide timing calibration at the crystal level. In the proposed method, the timing calibration process was formulated as a linear problem. To robustly optimize the timing resolution, a TV constraint was added to the linear equation. Moreover, to solve the computer memory problem associated with the calculation of the timing calibration factors for systems with a large number of crystals, the merge component was used for obtaining the crystal level timing calibration values. Compared with other conventional methods, the data measured from a standard cylindrical phantom filled with a radioisotope solution was sufficient for performing a high-precision crystal-level timing calibration. In this paper, both simulation and experimental studies were performed to demonstrate the effectiveness and robustness of the TV merge method. We compare the timing resolutions of a 22Na point source, which was located in the field of view (FOV) of the brain PET system, with various calibration techniques. After implementing the TV merge method, the timing resolution improved from 3.34 ns at full width at half maximum (FWHM) to 2.31 ns FWHM.

FTIR Calibration Methods and Issues

Science.gov (United States)

Perron, Gaetan

Over the past 10 years, several space-borne FTIR missions were launched for atmospheric research, environmental monitoring and meteorology. One can think of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) launched by the European Space Agency, the Atmospheric Chemistry Experiment (ACE) launched by the Canadian Space Agency, the Tropospheric Emission Spectrometer (TES) launched by NASA and the Infrared Atmospheric Sounding Interferometer (IASI) launched by Eumetsat in Europe. Others are near to be launched, namely the Cross-track Infrared Sounder (CrIS) from the Integrated Program Of- fice in the United States and the Thermal And Near infrared Sensor for carbon Observation (TANSO) from the Japan Aerospace Exploration Agency. Moreover, several missions under definition foresee the use of this technology as sensor, e.g. Meteosat Third Generation (MTG), Eumetsat Polar System (EPS) and the Premier mission, one of the six candidates of the next ESA Earth Explorer Core Mission. In order to produce good quality products, calibration is essential. Calibrated data is the output of three main sub-systems that are tightly coupled: the instrument, the calibration targets and the level 1B processor. Calibration requirements must be carefully defined and propagated to each sub-system. Often, they are carried out by different parties which add to the complexity. Under budget and schedule pressure, some aspects are sometimes neglected and jeopardized final quality. For space-borne FTIR, level 1B outputs are spectra that are radiometrically, spectrally calibrated and geolocated. Radiometric calibration means to assign an intensity value in units to the y-axis. Spectral calibration means to assign to the x-axis the proper frequency value in units. Finally, geolocated means to assign a target position over the earth geoid i.e. longitude, latitude and altitude. This paper will present calibration methods and issues related to space-borne FTIR missions, e.g. two

Utility of the Static-99 and Static-99R With Latino Sex Offenders.

Science.gov (United States)

Leguízamo, Alejandro; Lee, Seung C; Jeglic, Elizabeth L; Calkins, Cynthia

2017-12-01

The predictive validity of the Static-99 measures with ethnic minorities in the United States has only recently been assessed with mixed results. We assessed the predictive validity of the Static-99 and Static-99R with a sample of Latino sex offenders ( N = 483) as well as with two subsamples (U.S.-born, including Puerto Rico, and non-U.S.-born). The overall sexual recidivism rate was very low (1.9%). Both the Static-99 measures were able to predict sexual recidivism for offenders born in the United States and Puerto Rico, but neither was effective in doing so for other Latino immigrants. Calibration analyses ( N = 303) of the Static-99R were consistent with the literature and provided support for the potential use of the measure with Latinos born in the United States and Puerto Rico. These findings and their implications are discussed as they pertain to the assessment of Latino sex offenders.

Method of Calibrating a Force Balance

Science.gov (United States)

Parker, Peter A. (Inventor); Rhew, Ray D. (Inventor); Johnson, Thomas H. (Inventor); Landman, Drew (Inventor)

2015-01-01

A calibration system and method utilizes acceleration of a mass to generate a force on the mass. An expected value of the force is calculated based on the magnitude and acceleration of the mass. A fixture is utilized to mount the mass to a force balance, and the force balance is calibrated to provide a reading consistent with the expected force determined for a given acceleration. The acceleration can be varied to provide different expected forces, and the force balance can be calibrated for different applied forces. The acceleration may result from linear acceleration of the mass or rotational movement of the mass.

Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

Energy Technology Data Exchange (ETDEWEB)

Yeo, Seung Hwa; Lee, Su Ryong; Lee, Choong Hoon [Seoul National University of Science and Technology, Seoul (Korea, Republic of)

2015-01-15

The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100 .deg .C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100 .deg. C.

Effect of gas temperature on flow rate characteristics of an averaging pitot tube type flow meter

International Nuclear Information System (INIS)

Yeo, Seung Hwa; Lee, Su Ryong; Lee, Choong Hoon

2015-01-01

The flow rate characteristics passing through an averaging Pitot tube (APT) while constantly controlling the flow temperature were studied through experiments and CFD simulations. At controlled temperatures of 25, 50, 75, and 100 .deg .C, the flow characteristics, in this case the upstream, downstream and static pressure at the APT flow meter probe, were measured as the flow rate was increased. The flow rate through the APT flow meter was represented using the H-parameter (hydraulic height) obtained by a combination of the differential pressure and the air density measured at the APT flow meter probe. Four types of H-parameters were defined depending on the specific combination. The flow rate and the upstream, downstream and static pressures measured at the APT flow meter while changing the H-parameters were simulated by means of CFD. The flow rate curves showed different features depending on which type of H-parameter was used. When using the constant air density value in a standard state to calculate the H-parameters, the flow rate increased linearly with the H-parameter and the slope of the flow rate curve according to the H-parameter increased as the controlled target air temperature was increased. When using different air density levels corresponding to each target air temperature to calculate the H-parameter, the slope of the flow rate curve according to the H-parameter was constant and the flow rate curve could be represented by a single line. The CFD simulation results were in good agreement with the experimental results. The CFD simulations were performed while increasing the air temperature to 1200 K. The CFD simulation results for high air temperatures were similar to those at the low temperature ranging from 25 to 100 .deg. C.

Calibrating page sized Gafchromic EBT3 films

Energy Technology Data Exchange (ETDEWEB)

Crijns, W.; Maes, F.; Heide, U. A. van der; Van den Heuvel, F. [Department of Radiation Oncology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium); Department ESAT/PSI-Medical Image Computing, Medical Imaging Research Center, KU Leuven, Herestraat 49, 3000 Leuven (Belgium); Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital, Plesmanlaan 121, 1066 CX Amsterdam (Netherlands); Department of Radiation Oncology, University Hospitals Leuven, Herestraat 49, 3000 Leuven (Belgium)

2013-01-15

Purpose: The purpose is the development of a novel calibration method for dosimetry with Gafchromic EBT3 films. The method should be applicable for pretreatment verification of volumetric modulated arc, and intensity modulated radiotherapy. Because the exposed area on film can be large for such treatments, lateral scan errors must be taken into account. The correction for the lateral scan effect is obtained from the calibration data itself. Methods: In this work, the film measurements were modeled using their relative scan values (Transmittance, T). Inside the transmittance domain a linear combination and a parabolic lateral scan correction described the observed transmittance values. The linear combination model, combined a monomer transmittance state (T{sub 0}) and a polymer transmittance state (T{sub {infinity}}) of the film. The dose domain was associated with the observed effects in the transmittance domain through a rational calibration function. On the calibration film only simple static fields were applied and page sized films were used for calibration and measurements (treatment verification). Four different calibration setups were considered and compared with respect to dose estimation accuracy. The first (I) used a calibration table from 32 regions of interest (ROIs) spread on 4 calibration films, the second (II) used 16 ROIs spread on 2 calibration films, the third (III), and fourth (IV) used 8 ROIs spread on a single calibration film. The calibration tables of the setups I, II, and IV contained eight dose levels delivered to different positions on the films, while for setup III only four dose levels were applied. Validation was performed by irradiating film strips with known doses at two different time points over the course of a week. Accuracy of the dose response and the lateral effect correction was estimated using the dose difference and the root mean squared error (RMSE), respectively. Results: A calibration based on two films was the optimal

Studying the method of linearization of exponential calibration curves

International Nuclear Information System (INIS)

Bunzh, Z.A.

1989-01-01

The results of study of the method for linearization of exponential calibration curves are given. The calibration technique and comparison of the proposed method with piecewise-linear approximation and power series expansion, are given

Calibration method for a carbon nanotube field-effect transistor biosensor

International Nuclear Information System (INIS)

Abe, Masuhiro; Murata, Katsuyuki; Ataka, Tatsuaki; Matsumoto, Kazuhiko

2008-01-01

An easy calibration method based on the Langmuir adsorption theory is proposed for a carbon nanotube field-effect transistor (NTFET) biosensor. This method was applied to three NTFET biosensors that had approximately the same structure but exhibited different characteristics. After calibration, their experimentally determined characteristics exhibited a good agreement with the calibration curve. The reason why the observed characteristics of these NTFET biosensors differed among the devices was that the carbon nanotube (CNT) that formed the channel was not uniform. Although the controlled growth of a CNT is difficult, it is shown that an NTFET biosensor can be easy calibrated using the proposed calibration method, regardless of the CNT channel structures

Experimental investigation of turbulent flow in the inlet region of an eccentric annulus

International Nuclear Information System (INIS)

Hartz, U.

1983-08-01

In a fully eccentric annulus with a radius-ratio of Rsub(i)/Rsub(a)=0.86 the mean flow components anti U, anti V, anti W and the 6 components of the Reynolds stress tensor have been measured. These measurements have been made with hot-wire-probes. Besides this the static pressure and the total pressure have been determined by means of static pressure probes and Pitot-tubes. Beginning with X/Dsub(H)=14 (Dsub(H)=14 mm) wallshearstress-measurements have been conducted also using a Pitot-tube with Preston's method. Additionally computations have been made with the codes VELASCO and BODYFIT. The 11 axial plains reached from X/Dsub(H)=0.05 from the entrance to X/Dsub(H)=357 with logarithmic scale. (orig./RW) [de

A New Online Calibration Method Based on Lord's Bias-Correction.

Science.gov (United States)

He, Yinhong; Chen, Ping; Li, Yong; Zhang, Shumei

2017-09-01

Online calibration technique has been widely employed to calibrate new items due to its advantages. Method A is the simplest online calibration method and has attracted many attentions from researchers recently. However, a key assumption of Method A is that it treats person-parameter estimates θ ^ s (obtained by maximum likelihood estimation [MLE]) as their true values θ s , thus the deviation of the estimated θ ^ s from their true values might yield inaccurate item calibration when the deviation is nonignorable. To improve the performance of Method A, a new method, MLE-LBCI-Method A, is proposed. This new method combines a modified Lord's bias-correction method (named as maximum likelihood estimation-Lord's bias-correction with iteration [MLE-LBCI]) with the original Method A in an effort to correct the deviation of θ ^ s which may adversely affect the item calibration precision. Two simulation studies were carried out to explore the performance of both MLE-LBCI and MLE-LBCI-Method A under several scenarios. Simulation results showed that MLE-LBCI could make a significant improvement over the ML ability estimates, and MLE-LBCI-Method A did outperform Method A in almost all experimental conditions.

Optimized star sensors laboratory calibration method using a regularization neural network.

Science.gov (United States)

Zhang, Chengfen; Niu, Yanxiong; Zhang, Hao; Lu, Jiazhen

2018-02-10

High-precision ground calibration is essential to ensure the performance of star sensors. However, the complex distortion and multi-error coupling have brought great difficulties to traditional calibration methods, especially for large field of view (FOV) star sensors. Although increasing the complexity of models is an effective way to improve the calibration accuracy, it significantly increases the demand for calibration data. In order to achieve high-precision calibration of star sensors with large FOV, a novel laboratory calibration method based on a regularization neural network is proposed. A multi-layer structure neural network is designed to represent the mapping of the star vector and the corresponding star point coordinate directly. To ensure the generalization performance of the network, regularization strategies are incorporated into the net structure and the training algorithm. Simulation and experiment results demonstrate that the proposed method can achieve high precision with less calibration data and without any other priori information. Compared with traditional methods, the calibration error of the star sensor decreased by about 30%. The proposed method can satisfy the precision requirement for large FOV star sensors.

Review of control rod calibration methods for irradiated AGRs

Energy Technology Data Exchange (ETDEWEB)

Telford, A. R.R.

1975-10-15

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 spatial effects which have not needed consideration in earlier reactors but which in CAGR would need very careful evaluation.

An Experimental Evaluation of the Performance of Two Combination Pitot Pressure Probes

Science.gov (United States)

Arend, David J.; Saunders, John D.

2009-01-01

Experimental tests have been completed which recorded the ability of two combination steady state and high response time varying Pitot probe designs to accurately measure steady stagnation pressure at a single location in a flow field. Tests were conducted of double-barreled and coannular Prati probes in a 3.5 in. diameter free jet probe calibration facility from Mach 0.1 to 0.9. Geometric symmetry and pitch (-40 deg to 40 deg) and yaw (0 deg to 40 deg) angle actuation were used to fully evaluate the probes. These tests revealed that the double-barreled configuration induced error in its steady state measurement at zero incidence that increased consistently with jet Mach number to 1.1 percent at Mach 0.9. For all Mach numbers, the double-barreled probe nulled at a pitch angle of approximately 7.0 deg and provided inconsistent measurements when yawed. The double-barreled probe provided adequate measurements via both its steady state and high response tubes (within +/- 0.15 percent accuracy) over unacceptable ranges of biased pitch and inconsistent yaw angles which varied with Mach number. By comparison, the coannular probe provided accurate measurements (at zero incidence) for all jet Mach numbers as well as over a flow angularity range which varied from +/- 26.0 deg at Mach 0.3 deg to +/- 14.0 deg at Mach 0.9. Based on these results, the Prati probe is established as the preferred design. Further experimental tests are recommended to document the frequency response characteristics of the Prati probe.

Precision and accuracy of the static GNSS system for surveying networks used in Civil Engineering

Directory of Open Access Journals (Sweden)

Nixon Alexander Correa Muñoz

2018-01-01

Full Text Available A field check was implemented for calibrating surveying equipment. It was geo-referenced with a Total Station Theodolite and by implementing procedures concerning repeatability and reproducibility. We carried out GNSS (Global Navigation Satellite System static positioning with double frequency equipment, sensitizing occupation times, day times, uncorrected coordinates subjected to a differential correction procedure and type of coordinates obtained. This facilitated an evaluation of precision and accuracy for the GNSS positioning with the static method, which gave a global RMSE (root mean square error of 1 cm for conditions with no multipath effect and 4 cm for field calibration points close to buildings. Additionally, optimal results for occupation times of 30 minutes were found, and the need to use planar Cartesian coordinates to ensure compatibility with the surveys using electronic measurement of distances, which allows the use of the static GNSS positioning for geo-referencing precise surveying networks, and can be used in different applications in Civil Engineering.

Calibration of high resolution digital camera based on different photogrammetric methods

International Nuclear Information System (INIS)

Hamid, N F A; Ahmad, A

2014-01-01

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

Real-Time Flight Path Optimization for Tracking Stop-and-Go Targets with Micro Air Vehicles

Science.gov (United States)

2008-03-01

Guard with jealous attention the public liberty. Suspect everyone who approaches that jewel.” Patrick Henry “It is a universal...Kestrel autopilot. Given a known airspeed (from pitot -static data) and GPS ground speed, the wind speed and direction can be readily derived. Wind...automatically without any input from the user. Because the wind data is derived from GPS and pitot - static data, it is calculated onboard the autopilot and is

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.)

Simple and Reliable Method to Estimate the Fingertip Static Coefficient of Friction in Precision Grip.

Science.gov (United States)

Barrea, Allan; Bulens, David Cordova; Lefevre, Philippe; Thonnard, Jean-Louis

2016-01-01

The static coefficient of friction (µ static ) plays an important role in dexterous object manipulation. Minimal normal force (i.e., grip force) needed to avoid dropping an object is determined by the tangential force at the fingertip-object contact and the frictional properties of the skin-object contact. Although frequently assumed to be constant for all levels of normal force (NF, the force normal to the contact), µ static actually varies nonlinearly with NF and increases at low NF levels. No method is currently available to measure the relationship between µ static and NF easily. Therefore, we propose a new method allowing the simple and reliable measurement of the fingertip µ static at different NF levels, as well as an algorithm for determining µ static from measured forces and torques. Our method is based on active, back-and-forth movements of a subject's finger on the surface of a fixed six-axis force and torque sensor. µ static is computed as the ratio of the tangential to the normal force at slip onset. A negative power law captures the relationship between µ static and NF. Our method allows the continuous estimation of µ static as a function of NF during dexterous manipulation, based on the relationship between µ static and NF measured before manipulation.

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....

Evaluation of methods to calibrate radiation survey meters

International Nuclear Information System (INIS)

Robinson, R.C.; Arbeau, N.D.

1987-04-01

Calibration requirements for radiation survey meters used in industrial radiography have been reviewed. Information obtained from a literature search, discussions with CSLD inspectors and firms performing calibrations has been considered. Based on this review a set of minimum calibration requirements was generated which, when met, will determine that the survey meter is suited for measurements described in the current AEC Regulations that apply to industrial radiography equipment. These requirements are presented in this report and may be used as guidelines for evaluating calibration methods proposed or in use in industry. 39 refs

Quasi-static displacement calibration system for a "Violin-Mode" shadow-sensor intended for Gravitational Wave detector suspensions

Science.gov (United States)

Lockerbie, N. A.; Tokmakov, K. V.

2014-10-01

This paper describes the design of, and results from, a calibration system for optical linear displacement (shadow) sensors. The shadow sensors were designed to detect "Violin-Mode" (VM) resonances in the 0.4 mm diameter silica fibre suspensions of the test masses/mirrors of Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave interferometers. Each sensor illuminated the fibre under test, so as to cast its narrow shadow onto a "synthesized split photodiode" detector, the shadow falling over adjacent edges of the paired photodiodes. The apparatus described here translated a vertically orientated silica test fibre horizontally through a collimated Near InfraRed illuminating beam, whilst simultaneously capturing the separate DC "shadow notch" outputs from each of the paired split photodiode detectors. As the ratio of AC to DC photocurrent sensitivities to displacement was known, a calibration of the DC response to quasi-static shadow displacement allowed the required AC sensitivity to vibrational displacement to be found. Special techniques are described for generating the required constant scan rate for the test fibre using a DC motor-driven stage, for removing "jitter" at such low translation rates from a linear magnetic encoder, and so for capturing the two shadow-notch signals at each micrometre of the test fibre's travel. Calibration, across the four detectors of this work, gave a vibrational responsivity in voltage terms of (9.45 ± 1.20) MV (rms)/m, yielding a VM displacement sensitivity of (69 ± 13) pm (rms)/√Hz, at 500 Hz, over the required measuring span of ±0.1 mm.

A Monte Carlo implementation of the predictor-corrector Quasi-Static method

International Nuclear Information System (INIS)

Hackemack, M. W.; Ragusa, J. C.; Griesheimer, D. P.; Pounders, J. M.

2013-01-01

The Quasi-Static method (QS) is a useful tool for solving reactor transients since it allows for larger time steps when updating neutron distributions. Because of the beneficial attributes of Monte Carlo (MC) methods (exact geometries and continuous energy treatment), it is desirable to develop a MC implementation for the QS method. In this work, the latest version of the QS method known as the Predictor-Corrector Quasi-Static method is implemented. Experiments utilizing two energy-groups provide results that show good agreement with analytical and reference solutions. The method as presented can easily be implemented in any continuous energy, arbitrary geometry, MC code. (authors)

Micro manometer and pitot tube for measuring the velocity distribution in a natural convection water stream between two vertical parallel plates (1961); Micromano metre et tube de pitot destines a l'exploration du profil de vitesse dans un ecoulement d'eau de convection naturelle entre deux plaques verticales paralleles (1961)

Energy Technology Data Exchange (ETDEWEB)

Santon, L; Vernier, Ph [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1961-07-01

For heat transfer studies in certain cases of cooling in swimming-pool type nuclear reactors, a knowledge of the distribution of the velocities between two heating elements is of prime importance. A Pitot tube and a micro-manometer have been developed for making these measurements on an experimental model. (authors) [French] Pour l'etude du transfert de chaleur dans certains cas de refroidissement des reacteurs nucleaires du type piscine, la connaissance de la repartition des vitesses entre deux elements chauffants est primordiale. On a mis au point un tube de Pitot et un micromanometre pour effectuer ces mesures sur une maquette experimentale. (auteurs)

Application of effective variance method for contamination monitor calibration

International Nuclear Information System (INIS)

Goncalez, O.L.; Freitas, I.S.M. de.

1990-01-01

In this report, the calibration of a thin window Geiger-Muller type monitor for alpha superficial contamination is presented. The calibration curve is obtained by the method of the least-squares fitting with effective variance. The method and the approach for the calculation are briefly discussed. (author)

The improved quasi-static method vs the direct method: a case study for CANDU reactor transients

International Nuclear Information System (INIS)

Kaveh, S.; Koclas, J.; Roy, R.

1999-01-01

Among the large number of methods for the transient analysis of nuclear reactors, the improved quasi-static procedure is one of the most widely used. In recent years, substantial increase in both computer speed and memory has motivated a rethinking of the limitations of this method. The overall goal of the present work is a systematic comparison between the improved quasi-static and the direct method (mesh-centered finite difference) for realistic CANDU transient simulations. The emphasis is on the accuracy of the solutions as opposed to the computational speed. Using the computer code NDF, a typical realistic transient of CANDU reactor has been analyzed. In this transient the response of the reactor regulating system to a substantial local perturbation (sudden extraction of the five adjuster rods) has been simulated. It is shown that when updating the detector responses is of major importance, it is better to use a well-optimized direct method rather than the improved quasi-static method. (author)

Calibration Method to Eliminate Zeroth Order Effect in Lateral Shearing Interferometry

Science.gov (United States)

Fang, Chao; Xiang, Yang; Qi, Keqi; Chen, Dawei

2018-04-01

In this paper, a calibration method is proposed which eliminates the zeroth order effect in lateral shearing interferometry. An analytical expression of the calibration error function is deduced, and the relationship between the phase-restoration error and calibration error is established. The analytical results show that the phase-restoration error introduced by the calibration error is proportional to the phase shifting error and zeroth order effect. The calibration method is verified using simulations and experiments. The simulation results show that the phase-restoration error is approximately proportional to the phase shift error and zeroth order effect, when the phase shifting error is less than 2° and the zeroth order effect is less than 0.2. The experimental result shows that compared with the conventional method with 9-frame interferograms, the calibration method with 5-frame interferograms achieves nearly the same restoration accuracy.

A novel iterative energy calibration method for composite germanium detectors

International Nuclear Information System (INIS)

Pattabiraman, N.S.; Chintalapudi, S.N.; Ghugre, S.S.

2004-01-01

An automatic method for energy calibration of the observed experimental spectrum has been developed. The method presented is based on an iterative algorithm and presents an efficient way to perform energy calibrations after establishing the weights of the calibration data. An application of this novel technique for data acquired using composite detectors in an in-beam γ-ray spectroscopy experiment is presented

A novel iterative energy calibration method for composite germanium detectors

Energy Technology Data Exchange (ETDEWEB)

Pattabiraman, N.S.; Chintalapudi, S.N.; Ghugre, S.S. E-mail: ssg@alpha.iuc.res.in

2004-07-01

An automatic method for energy calibration of the observed experimental spectrum has been developed. The method presented is based on an iterative algorithm and presents an efficient way to perform energy calibrations after establishing the weights of the calibration data. An application of this novel technique for data acquired using composite detectors in an in-beam {gamma}-ray spectroscopy experiment is presented.

Method and apparatus for calibrating spectrophotometers

NARCIS (Netherlands)

Schreutelkamp, F.H.

2003-01-01

The present invention relates to a method of calibrating spectrophotometers by placing one or more filters in the light path of the spectrophotometer and measuring the amount of radiation by means of a detector. The present invention furthermore relates to an apparatus to be used with such a method.

LOFT ECC Pitot Tube and Thermocouple Rake Penetration thermal analysis

International Nuclear Information System (INIS)

Tolan, B.J.

1977-01-01

A thermal analysis of the LOFT ECC Pitot Tube and Thermocouple Rake Penetration was performed using COUPLE, a two-dimensional finite element computer code. Four transients which conservatively cover all transients the rake will be exposed to were included in this analysis in order to comply with the ASME Code Section III requirements. The transients conservatively cover hot and cold leg operation, and nuclear and nonnuclear operation. The four transients include the LOCE with ECC injection transient, the single control rod drop transient, the scram transient, and the heatup with 0 to 100% load change transient. Temperature distributions in the rake were obtained for each of the four transients and several plots of node temperatures vs. time are given

Design of calibration method in neutron and individual dosimeter

International Nuclear Information System (INIS)

Belkhodia, M.

1984-12-01

Usually albedo dosemeters are calibrated with beam of monoenergetic neutrons. Since neutron energy around neutron sources varies greatly, we applied the calibration method to a mixed field whose energy spectrum lies between 0.025 ev and 10 Mev. The method is based on a mathematical model that deals with the dosimeter response as a function at the neutron energy. The measurements carried out with solid state nuclear track detectors show the dosimeter practical aspect. The albedo dosimeter calibration gave results on good agreement with the international institution recommendations

Latest Developments on Obtaining Accurate Measurements with Pitot Tubes in ZPG Turbulent Boundary Layers

Science.gov (United States)

Nagib, Hassan; Vinuesa, Ricardo

2013-11-01

Ability of available Pitot tube corrections to provide accurate mean velocity profiles in ZPG boundary layers is re-examined following the recent work by Bailey et al. Measurements by Bailey et al., carried out with probes of diameters ranging from 0.2 to 1.89 mm, together with new data taken with larger diameters up to 12.82 mm, show deviations with respect to available high-quality datasets and hot-wire measurements in the same Reynolds number range. These deviations are significant in the buffer region around y+ = 30 - 40 , and lead to disagreement in the von Kármán coefficient κ extracted from profiles. New forms for shear, near-wall and turbulence corrections are proposed, highlighting the importance of the latest one. Improved agreement in mean velocity profiles is obtained with new forms, where shear and near-wall corrections contribute with around 85%, and remaining 15% of the total correction comes from turbulence correction. Finally, available algorithms to correct wall position in profile measurements of wall-bounded flows are tested, using as benchmark the corrected Pitot measurements with artificially simulated probe shifts and blockage effects. We develop a new scheme, κB - Musker, which is able to accurately locate wall position.

A Visual Servoing-Based Method for ProCam Systems Calibration

Directory of Open Access Journals (Sweden)

Jeremie Mosnier

2013-10-01

Full Text Available 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.

A geometry calibration method for rotation translation trajectory

International Nuclear Information System (INIS)

Zhang Jun; Yan Bin; Li Lei; Lu Lizhong; Zhang Feng

2013-01-01

In cone-beam CT imaging system, it is difficult to directly measure the geometry parameters. In this paper, a geometry calibration method for rotation translation trajectory is proposed. Intrinsic parameters are solved from the relationship built on geometry parameter of the system and projection trajectory of calibration object. Parameters of rotation axis are extrapolated from the unified intrinsic parameter, and geometry parameters of the idle trajectory are acquired too. The calibration geometry can be analytically determined using explicit formulae, it can avoid getting into local optimum in iterative way. Simulation experiments are carried out on misaligned geometry, experiment results indicate that geometry artifacts due to misaligned geometry are effectively depressed by the proposed method, and the image quality is enhanced. (authors)

Technical Note: Characterization of a static thermal-gradient CCN counter

Directory of Open Access Journals (Sweden)

G. P. Frank

2007-06-01

Full Text Available The static (parallel-plate thermal-gradient diffusion chamber (SDC was one of the first instruments designed to measure cloud condensation nuclei (CCN concentrations as a function of supersaturation. It has probably also been the most widely used type of CCN counter. This paper describes the detailed experimental characterization of a SDC CCN counter, including calibration with respect to supersaturation and particle number concentration. In addition, we investigated the proposed effect of lowered supersaturation because of water vapor depletion with increasing particle concentration. The results obtained give a better understanding why and in which way it is necessary to calibrate the SDC CCN counter. The calibration method is described in detail and can, in parts, be used for calibrations also for other types of CCN counters.

We conclude the following: 1 it is important to experimentally calibrate SDC CCN counters with respect to supersaturation, and not only base the supersaturation on the theoretical description of the instrument; 2 the number concentration calibration needs to be performed as a function of supersaturation, also for SDC CCN counter using the photographic technique; and 3 we observed no evidence that water vapor depletion lowered the supersaturation.

Quasi-static displacement calibration system for a “Violin-Mode” shadow-sensor intended for Gravitational Wave detector suspensions

International Nuclear Information System (INIS)

Lockerbie, N. A.; Tokmakov, K. V.

2014-01-01

This paper describes the design of, and results from, a calibration system for optical linear displacement (shadow) sensors. The shadow sensors were designed to detect “Violin-Mode” (VM) resonances in the 0.4 mm diameter silica fibre suspensions of the test masses/mirrors of Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave interferometers. Each sensor illuminated the fibre under test, so as to cast its narrow shadow onto a “synthesized split photodiode” detector, the shadow falling over adjacent edges of the paired photodiodes. The apparatus described here translated a vertically orientated silica test fibre horizontally through a collimated Near InfraRed illuminating beam, whilst simultaneously capturing the separate DC “shadow notch” outputs from each of the paired split photodiode detectors. As the ratio of AC to DC photocurrent sensitivities to displacement was known, a calibration of the DC response to quasi-static shadow displacement allowed the required AC sensitivity to vibrational displacement to be found. Special techniques are described for generating the required constant scan rate for the test fibre using a DC motor-driven stage, for removing “jitter” at such low translation rates from a linear magnetic encoder, and so for capturing the two shadow-notch signals at each micrometre of the test fibre's travel. Calibration, across the four detectors of this work, gave a vibrational responsivity in voltage terms of (9.45 ± 1.20) MV (rms)/m, yielding a VM displacement sensitivity of (69 ± 13) pm (rms)/√Hz, at 500 Hz, over the required measuring span of ±0.1 mm

Quasi-static displacement calibration system for a “Violin-Mode” shadow-sensor intended for Gravitational Wave detector suspensions

Energy Technology Data Exchange (ETDEWEB)

Lockerbie, N. A.; Tokmakov, K. V. [SUPA (Scottish Universities Physics Alliance), Department of Physics, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG (United Kingdom)

2014-10-15

This paper describes the design of, and results from, a calibration system for optical linear displacement (shadow) sensors. The shadow sensors were designed to detect “Violin-Mode” (VM) resonances in the 0.4 mm diameter silica fibre suspensions of the test masses/mirrors of Advanced Laser Interferometer Gravitational Wave Observatory gravitational wave interferometers. Each sensor illuminated the fibre under test, so as to cast its narrow shadow onto a “synthesized split photodiode” detector, the shadow falling over adjacent edges of the paired photodiodes. The apparatus described here translated a vertically orientated silica test fibre horizontally through a collimated Near InfraRed illuminating beam, whilst simultaneously capturing the separate DC “shadow notch” outputs from each of the paired split photodiode detectors. As the ratio of AC to DC photocurrent sensitivities to displacement was known, a calibration of the DC response to quasi-static shadow displacement allowed the required AC sensitivity to vibrational displacement to be found. Special techniques are described for generating the required constant scan rate for the test fibre using a DC motor-driven stage, for removing “jitter” at such low translation rates from a linear magnetic encoder, and so for capturing the two shadow-notch signals at each micrometre of the test fibre's travel. Calibration, across the four detectors of this work, gave a vibrational responsivity in voltage terms of (9.45 ± 1.20) MV (rms)/m, yielding a VM displacement sensitivity of (69 ± 13) pm (rms)/√Hz, at 500 Hz, over the required measuring span of ±0.1 mm.

Kinematic parameter calibration method for industrial robot manipulator using the relative position

International Nuclear Information System (INIS)

Ha, In Chul

2008-01-01

A new calibration method for industrial robot system calibration on a manufacturing floor is presented in this paper. To calibrate the robot system, a laser sensor to measure the distance between robot tool and measurement surface is attached to the robot end-effector and a grid is established in the floor. Given two position command pulses for a robot manipulator and using the position difference between two command pulses, the relative position measurement calibration method will find the real robot kinematic parameters. The procedures developed have been applied to an industrial robot. Finally, the effects of the models used to calibrate the robot are discussed. This calibration method represents an effective, low cost and feasible technique for the industrial robot calibration in lab. projects and industrial environments

A method to calibrate a solar pyranometer for measuring reference diffuse irradiance

Energy Technology Data Exchange (ETDEWEB)

Reda, I.; Stoffel, T.; Myers, D. [National Renewable Energy Laboratory, Golden, CO (United States)

2003-02-01

Accurate pyranometer calibrations, traceable to internationally recognized standards, are critical for solar irradiance measurements. One calibration method is the component summation, where the pyranometers are calibrated outdoors under clear sky conditions, and the reference global solar irradiance is calculated as the sum of two reference components, the diffuse and subtended beam solar irradiances. The beam component is measured with pyrheliometers traceable to the World Radiometric Reference, while there is no internationally recognized reference for the diffuse component. In the absence of such a reference, we present a method to consistently calibrate pyranometers for measuring the diffuse component with an estimated uncertainty of {+-} (3% of reading +1 W/m{sup 2}). The method is based on using a modified shade/unshade method, and pyranometers with less than 1 W/m{sup 2} thermal offset errors. We evaluated the consistency of our method by calibrating three pyranometers four times. Calibration results show that the responsivity change is within {+-} 0.52% for the three pyranometers. We also evaluated the effect of calibrating pyranometers unshaded, then using them shaded to measure diffuse irradiance. We calibrated three unshaded pyranometers using the component summation method. Their outdoor measurements of clear sky diffuse irradiance, from sunrise to sundown, showed that the three calibrated pyranometers can be used to measure the diffuse irradiance to within {+-} 1.4 W/m{sup 2} variation from the reference irradiance. (author)

A calibration method for fringe reflection technique based on the analytical phase-slope description

Science.gov (United States)

Wu, Yuxiang; Yue, Huimin; Pan, Zhipeng; Liu, Yong

2018-05-01

The fringe reflection technique (FRT) has been one of the most popular methods to measure the shape of specular surface these years. The existing system calibration methods of FRT usually contain two parts, which are camera calibration and geometric calibration. In geometric calibration, the liquid crystal display (LCD) screen position calibration is one of the most difficult steps among all the calibration procedures, and its accuracy is affected by the factors such as the imaging aberration, the plane mirror flatness, and LCD screen pixel size accuracy. In this paper, based on the deduction of FRT analytical phase-slope description, we present a novel calibration method with no requirement to calibrate the position of LCD screen. On the other hand, the system can be arbitrarily arranged, and the imaging system can either be telecentric or non-telecentric. In our experiment of measuring the 5000mm radius sphere mirror, the proposed calibration method achieves 2.5 times smaller measurement error than the geometric calibration method. In the wafer surface measuring experiment, the measurement result with the proposed calibration method is closer to the interferometer result than the geometric calibration method.

Calibration of NASA Turbulent Air Motion Measurement System

Science.gov (United States)

Barrick, John D. W.; Ritter, John A.; Watson, Catherine E.; Wynkoop, Mark W.; Quinn, John K.; Norfolk, Daniel R.

1996-01-01

A turbulent air motion measurement system (TAMMS) was integrated onboard the Lockheed 188 Electra airplane (designated NASA 429) based at the Wallops Flight Facility in support of the NASA role in global tropospheric research. The system provides air motion and turbulence measurements from an airborne platform which is capable of sampling tropospheric and planetary boundary-layer conditions. TAMMS consists of a gust probe with free-rotating vanes mounted on a 3.7-m epoxy-graphite composite nose boom, a high-resolution inertial navigation system (INS), and data acquisition system. A variation of the tower flyby method augmented with radar tracking was implemented for the calibration of static pressure position error and air temperature probe. Additional flight calibration maneuvers were performed remote from the tower in homogeneous atmospheric conditions. System hardware and instrumentation are described and the calibration procedures discussed. Calibration and flight results are presented to illustrate the overall ability of the system to determine the three-component ambient wind fields during straight and level flight conditions.

Pitot-probe displacement in a supersonic turbulent boundary layer

Science.gov (United States)

Allen, J. M.

1972-01-01

Eight circular pitot probes ranging in size from 2 to 70 percent of the boundary-layer thickness were tested to provide experimental probe displacement results in a two-dimensional turbulent boundary layer at a nominal free-stream Mach number of 2 and unit Reynolds number of 8 million per meter. The displacement obtained in the study was larger than that reported by previous investigators in either an incompressible turbulent boundary layer or a supersonic laminar boundary layer. The large probes indicated distorted Mach number profiles, probably due to separation. When the probes were small enough to cause no appreciable distortion, the displacement was constant over most of the boundary layer. The displacement in the near-wall region decreased to negative displacement in some cases. This near-wall region was found to extend to about one probe diameter from the test surface.

Lateral force calibration in atomic force microscopy: A new lateral force calibration method and general guidelines for optimization

International Nuclear Information System (INIS)

Cannara, Rachel J.; Eglin, Michael; Carpick, Robert W.

2006-01-01

Proper force calibration is a critical step in atomic and lateral force microscopies (AFM/LFM). The recently published torsional Sader method [C. P. Green et al., Rev. Sci. Instrum. 75, 1988 (2004)] facilitates the calculation of torsional spring constants of rectangular AFM cantilevers by eliminating the need to obtain information or make assumptions regarding the cantilever's material properties and thickness, both of which are difficult to measure. Complete force calibration of the lateral signal in LFM requires measurement of the lateral signal deflection sensitivity as well. In this article, we introduce a complete lateral force calibration procedure that employs the torsional Sader method and does not require making contact between the tip and any sample. In this method, a colloidal sphere is attached to a 'test' cantilever of the same width, but different length and material as the 'target' cantilever of interest. The lateral signal sensitivity is calibrated by loading the colloidal sphere laterally against a vertical sidewall. The signal sensitivity for the target cantilever is then corrected for the tip length, total signal strength, and in-plane bending of the cantilevers. We discuss the advantages and disadvantages of this approach in comparison with the other established lateral force calibration techniques, and make a direct comparison with the 'wedge' calibration method. The methods agree to within 5%. The propagation of errors is explicitly considered for both methods and the sources of disagreement discussed. Finally, we show that the lateral signal sensitivity is substantially reduced when the laser spot is not centered on the detector

Influence of probe geometry on pitot-probe displacement in supersonic turbulent flow

Science.gov (United States)

Allen, J. M.

1975-01-01

An experiment was conducted to determine the varying effects of six different probe-tip and support-shaft configurations on pitot tube displacement. The study was stimulated by discrepancies between supersonic wind-tunnel tests conducted by Wilson and Young (1949) and Allen (1972). Wilson (1973) had concluded that these discrepancies were caused by differences in probe geometry. It is shown that in fact, no major differences in profiles of streamwise velocity over streamwise velocity at boundary-layer edge vs normal coordinate over boundary-layer total thickness result from geometry. The true cause of the discrepancies, however, remains to be discovered.

A new systematic calibration method of ring laser gyroscope inertial navigation system

Science.gov (United States)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Xiong, Zhenyu; Long, Xingwu

2016-10-01

Inertial navigation system has been the core component of both military and civil navigation systems. Before the INS is put into application, it is supposed to be calibrated in the laboratory in order to compensate repeatability error caused by manufacturing. Discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed theories of error inspiration and separation in detail and presented a new systematic calibration method for ring laser gyroscope inertial navigation system. Error models and equations of calibrated Inertial Measurement Unit are given. Then proper rotation arrangement orders are depicted in order to establish the linear relationships between the change of velocity errors and calibrated parameter errors. Experiments have been set up to compare the systematic errors calculated by filtering calibration result with those obtained by discrete calibration result. The largest position error and velocity error of filtering calibration result are only 0.18 miles and 0.26m/s compared with 2 miles and 1.46m/s of discrete calibration result. These results have validated the new systematic calibration method and proved its importance for optimal design and accuracy improvement of calibration of mechanically dithered ring laser gyroscope inertial navigation system.

A holistic calibration method with iterative distortion compensation for stereo deflectometry

Science.gov (United States)

Xu, Yongjia; Gao, Feng; Zhang, Zonghua; Jiang, Xiangqian

2018-07-01

This paper presents a novel holistic calibration method for stereo deflectometry system to improve the system measurement accuracy. The reconstruction result of stereo deflectometry is integrated with the calculated normal data of the measured surface. The calculation accuracy of the normal data is seriously influenced by the calibration accuracy of the geometrical relationship of the stereo deflectometry system. Conventional calibration approaches introduce form error to the system due to inaccurate imaging model and distortion elimination. The proposed calibration method compensates system distortion based on an iterative algorithm instead of the conventional distortion mathematical model. The initial value of the system parameters are calculated from the fringe patterns displayed on the systemic LCD screen through a reflection of a markless flat mirror. An iterative algorithm is proposed to compensate system distortion and optimize camera imaging parameters and system geometrical relation parameters based on a cost function. Both simulation work and experimental results show the proposed calibration method can significantly improve the calibration and measurement accuracy of a stereo deflectometry. The PV (peak value) of measurement error of a flat mirror can be reduced to 69.7 nm by applying the proposed method from 282 nm obtained with the conventional calibration approach.

F-16D Pacer Calibration Techniques (SPEED PACER)

Science.gov (United States)

2012-07-01

from the calibration FTTs and therefore, would add flight hours to accomplish. Other variables used in creation of the total costs are as follows: F-16... ZULU Time --- ∆ static source error correction n/d Δ Psic static pressure instrument error correction inHg Δ Ptic total pressure

Model Robust Calibration: Method and Application to Electronically-Scanned Pressure Transducers

Science.gov (United States)

Walker, Eric L.; Starnes, B. Alden; Birch, Jeffery B.; Mays, James E.

2010-01-01

This article presents the application of a recently developed statistical regression method to the controlled instrument calibration problem. The statistical method of Model Robust Regression (MRR), developed by Mays, Birch, and Starnes, is shown to improve instrument calibration by reducing the reliance of the calibration on a predetermined parametric (e.g. polynomial, exponential, logarithmic) model. This is accomplished by allowing fits from the predetermined parametric model to be augmented by a certain portion of a fit to the residuals from the initial regression using a nonparametric (locally parametric) regression technique. The method is demonstrated for the absolute scale calibration of silicon-based pressure transducers.

Verification of the ISO calibration method for field pyranometers under tropical sky conditions

Science.gov (United States)

Janjai, Serm; Tohsing, Korntip; Pattarapanitchai, Somjet; Detkhon, Pasakorn

2017-02-01

Field pyranomters need to be annually calibrated and the International Organization for Standardization (ISO) has defined a standard method (ISO 9847) for calibrating these pyranometers. According to this standard method for outdoor calibration, the field pyranometers have to be compared to a reference pyranometer for the period of 2 to 14 days, depending on sky conditions. In this work, the ISO 9847 standard method was verified under tropical sky conditions. To verify the standard method, calibration of field pyranometers was conducted at a tropical site located in Nakhon Pathom (13.82o N, 100.04o E), Thailand under various sky conditions. The conditions of the sky were monitored by using a sky camera. The calibration results for different time periods used for the calibration under various sky conditions were analyzed. It was found that the calibration periods given by this standard method could be reduced without significant change in the final calibration result. In addition, recommendation and discussion on the use of this standard method in the tropics were also presented.

An investigation of calibration methods for solution calorimetry.

Science.gov (United States)

Yff, Barbara T S; Royall, Paul G; Brown, Marc B; Martin, Gary P

2004-01-28

Solution calorimetry has been used in a number of varying applications within pharmaceutical research as a technique for the physical characterisation of pharmaceutical materials, such as quantifying small degrees of amorphous content, identifying polymorphs and investigating interactions between drugs and carbohydrates or proteins and carbohydrates. A calibration test procedure is necessary to validate the instrumentation; a few of the suggested calibration reactions are the enthalpies of solution associated with dissolving Tris in 0.1 M HCl or NaCl, KCl or propan-1-ol in water. In addition, there are a number of different methods available to determine enthalpies of solution from the experimental data provided by the calorimeter, for example, the Regnault-Pfaundler's method, a graphical extrapolation based on the Dickinson method, or a manual integration-based method. Thus, the aim of the study was to investigate how each of these methods influences the values for the enthalpy of solution. Experiments were performed according to the method outlined by Hogan and Buckton [Int. J. Pharm. 207 (2000) 57] using KCl (samples of 50, 100 and 200 mg), Tris and sucrose as calibrants. For all three materials the manual integration method was found to be the most consistent with the KCl in water (sample mass of 200 mg) being the most precise. Thus, this method is recommended for the validation of solution calorimeters.

Fast film dosimetry calibration method for IMRT treatment plan verification

International Nuclear Information System (INIS)

Schwob, N.; Wygoda, A.

2004-01-01

Intensity-Modulated Radiation Therapy (IMRT) treatments are delivered dynamically and as so, require routinely performed verification measurements [1]. Radiographic film dosimetry is a well-adapted method for integral measurements of dynamic treatments fields, with some drawbacks related to the known problems of dose calibration of films. Classically, several films are exposed to increasing doses, and a Net Optical Density (N.O.D) vs. dose sensitometric curve (S.C.) is generated. In order to speed up the process, some authors have developed a method based on the irradiation of a single film with a non-uniform pattern of O.D., delivered with a dynamic MLC. However, this curve still needs to be calibrated to dose by the means of measurements in a water phantom. It is recommended to make a new calibration for every series of measurements, in order to avoid the processing quality dependence of the film response. These frequent measurements are very time consuming. We developed a simple method for quick dose calibration of films, including a check of the accuracy of the calibration curve obtained

A Simple Method for Static Load Balancing of Parallel FDTD Codes

DEFF Research Database (Denmark)

Franek, Ondrej

2016-01-01

A static method for balancing computational loads in parallel implementations of the finite-difference timedomain method is presented. The procedure is fairly straightforward and computationally inexpensive, thus providing an attractive alternative to optimization techniques. The method is descri...

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...

Two laboratory methods for the calibration of GPS speed meters

International Nuclear Information System (INIS)

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

2015-01-01

The set-ups of two calibration systems are presented to investigate calibration methods of GPS speed meters. The GPS speed meter calibrated is a special type of high accuracy speed meter for vehicles which uses Doppler demodulation of GPS signals to calculate the measured speed of a moving target. Three experiments are performed: including simulated calibration, field-test signal replay calibration, and in-field test comparison with an optical speed meter. The experiments are conducted at specific speeds in the range of 40–180 km h −1 with the same GPS speed meter as the device under calibration. The evaluation of measurement results validates both methods for calibrating GPS speed meters. The relative deviations between the measurement results of the GPS-based high accuracy speed meter and those of the optical speed meter are analyzed, and the equivalent uncertainty of the comparison is evaluated. The comparison results justify the utilization of GPS speed meters as reference equipment if no fewer than seven satellites are available. This study contributes to the widespread use of GPS-based high accuracy speed meters as legal reference equipment in traffic speed metrology. (paper)

High-accuracy self-calibration method for dual-axis rotation-modulating RLG-INS

Science.gov (United States)

Wei, Guo; Gao, Chunfeng; Wang, Qi; Wang, Qun; Long, Xingwu

2017-05-01

Inertial navigation system has been the core component of both military and civil navigation systems. Dual-axis rotation modulation can completely eliminate the inertial elements constant errors of the three axes to improve the system accuracy. But the error caused by the misalignment angles and the scale factor error cannot be eliminated through dual-axis rotation modulation. And discrete calibration method cannot fulfill requirements of high-accurate calibration of the mechanically dithered ring laser gyroscope navigation system with shock absorbers. This paper has analyzed the effect of calibration error during one modulated period and presented a new systematic self-calibration method for dual-axis rotation-modulating RLG-INS. Procedure for self-calibration of dual-axis rotation-modulating RLG-INS has been designed. The results of self-calibration simulation experiment proved that: this scheme can estimate all the errors in the calibration error model, the calibration precision of the inertial sensors scale factor error is less than 1ppm and the misalignment is less than 5″. These results have validated the systematic self-calibration method and proved its importance for accuracy improvement of dual -axis rotation inertial navigation system with mechanically dithered ring laser gyroscope.

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.

On the calibration methods for neutron moisture gauges

International Nuclear Information System (INIS)

Apostol, I.

1975-01-01

Theoretical and experimental calibration methods for devices using neutron sources to measure the water content in subsurface soil and other samples are investigated. Neutron flux density is evaluated by means of the two and three group diffusion and Fermi age theories. The correction criteria for the calibration curves are presented. The agreement of the theoretical curves with the determined experimental data may be considered as excellent. (author)

Practical use of control rod calibration system with the inverse kinetics method

International Nuclear Information System (INIS)

Yamanaka, Haruhiko; Hayashi, Kazuhiko; Motohashi, Jun; Kawashima, Kazuhito; Ichimura, Toshiyuki; Tamai, Kazuo; Takeuti, Mitsuo

2002-01-01

The control rod calibration results in the JRR-3 are used as a reactivity standard to measure and manage the reactivity change in the core. The total travel of all six control rods has been calibrated by an inverse kinetics method (IK method) during an annual maintenance period. The IK method has the great merit in saving measuring time compared with the conventional positive period method (PP method). The JRR-3 control rod calibration system was renovated and put into practical use in order to improve reliability and function by accumulating 10-year experience with the IK method in the JRR-3. The report shows the function, the performance and results of verification of the JRR-3 control rod calibration system. (author)

PEBBLES Simulation of Static Friction and New Static Friction Benchmark

International Nuclear Information System (INIS)

Cogliati, Joshua J.; Ougouag, Abderrafi M.

2010-01-01

Pebble bed reactors contain large numbers of spherical fuel elements arranged randomly. Determining the motion and location of these fuel elements is required for calculating certain parameters of pebble bed reactor operation. This paper documents the PEBBLES static friction model. This model uses a three dimensional differential static friction approximation extended from the two dimensional Cundall and Strack model. The derivation of determining the rotational transformation of pebble to pebble static friction force is provided. A new implementation for a differential rotation method for pebble to container static friction force has been created. Previous published methods are insufficient for pebble bed reactor geometries. A new analytical static friction benchmark is documented that can be used to verify key static friction simulation parameters. This benchmark is based on determining the exact pebble to pebble and pebble to container static friction coefficients required to maintain a stable five sphere pyramid.

Preparatory research to develop an operational method to calibrate airborne sensor data using a network of ground calibration sites

International Nuclear Information System (INIS)

Milton, E.J.; Smith, G.M.; Lawless, K.P.

1996-01-01

The objective of the research is to develop an operational method to convert airborne spectral radiance data to reflectance using a number of well-characterized ground calibration sites located around the UK. The study is in three phases. First, a pilot study has been conducted at a disused airfield in southern England to test the feasibility of the open-quote empirical line close-quote method of sensor calibration. The second phase is developing methods to predict temporal changes in the bidirectional reflectance of ground calibration sites. The final phase of the project will look at methods to extend such calibrations spatially. This paper presents some results from the first phase of this study. The viability of the empirical line method of correction is shown to depend upon the use of ground targets whose in-band reflectance encompasses that of the targets of interest in the spectral band(s) concerned. The experimental design for the second phase of the study, in which methods to predict temporal trends in the bidirectional reflectance of these sites will be developed, is discussed. Finally, it is planned to develop an automated method of searching through Landsat TM data for the UK to identify a number of candidate ground calibration sites for which the model can be tested. 11 refs., 5 figs., 5 tabs

Advanced Method of the Elastomagnetic Sensors Calibration

Directory of Open Access Journals (Sweden)

Mikulas Prascak

2004-01-01

Full Text Available Elastomagnetic method (EM method is a highly sensitive non-contact evaluation method for measuring tensile and compressive stress in steel. The latest development of measuring devices and EM sensors has shown that the thermomagnetic phenomenon has a stron influence on th accuracy during the EM sensor calibration. To eliminate the influence of this effect a two dimensional regression method is presented.

Comparison of the quasi-static method and the dynamic method for simulating fracture processes in concrete

Science.gov (United States)

Liu, J. X.; Deng, S. C.; Liang, N. G.

2008-02-01

Concrete is heterogeneous and usually described as a three-phase material, where matrix, aggregate and interface are distinguished. To take this heterogeneity into consideration, the Generalized Beam (GB) lattice model is adopted. The GB lattice model is much more computationally efficient than the beam lattice model. Numerical procedures of both quasi-static method and dynamic method are developed to simulate fracture processes in uniaxial tensile tests conducted on a concrete panel. Cases of different loading rates are compared with the quasi-static case. It is found that the inertia effect due to load increasing becomes less important and can be ignored with the loading rate decreasing, but the inertia effect due to unstable crack propagation remains considerable no matter how low the loading rate is. Therefore, an unrealistic result will be obtained if a fracture process including unstable cracking is simulated by the quasi-static procedure.

Calibrations of pocket dosemeters using a comparison method

International Nuclear Information System (INIS)

Somarriba V, I.

1996-01-01

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

An Improved Interferometric Calibration Method Based on Independent Parameter Decomposition

Science.gov (United States)

Fan, J.; Zuo, X.; Li, T.; Chen, Q.; Geng, X.

2018-04-01

Interferometric SAR is sensitive to earth surface undulation. The accuracy of interferometric parameters plays a significant role in precise digital elevation model (DEM). The interferometric calibration is to obtain high-precision global DEM by calculating the interferometric parameters using ground control points (GCPs). However, interferometric parameters are always calculated jointly, making them difficult to decompose precisely. In this paper, we propose an interferometric calibration method based on independent parameter decomposition (IPD). Firstly, the parameters related to the interferometric SAR measurement are determined based on the three-dimensional reconstruction model. Secondly, the sensitivity of interferometric parameters is quantitatively analyzed after the geometric parameters are completely decomposed. Finally, each interferometric parameter is calculated based on IPD and interferometric calibration model is established. We take Weinan of Shanxi province as an example and choose 4 TerraDEM-X image pairs to carry out interferometric calibration experiment. The results show that the elevation accuracy of all SAR images is better than 2.54 m after interferometric calibration. Furthermore, the proposed method can obtain the accuracy of DEM products better than 2.43 m in the flat area and 6.97 m in the mountainous area, which can prove the correctness and effectiveness of the proposed IPD based interferometric calibration method. The results provide a technical basis for topographic mapping of 1 : 50000 and even larger scale in the flat area and mountainous area.

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.

Digital Offset Calibration of an OPAMP Towards Improving Static Parameters of 90 nm CMOS DAC

Directory of Open Access Journals (Sweden)

D. Arbet

2014-09-01

Full Text Available In this paper, an on-chip self-calibrated 8-bit R-2R digital-to-analog converter (DAC based on digitally compensated input offset of the operational amplifier (OPAMP is presented. To improve the overall DAC performance, a digital offset cancellation method was used to compensate deviations in the input offset voltage of the OPAMP caused by process variations. The whole DAC as well as offset compensation circuitry were designed in a standard 90 nm CMOS process. The achieved results show that after the self-calibration process, the improvement of 48% in the value of DAC offset error is achieved.

Interferometric methods for mapping static electric and magnetic fields

DEFF Research Database (Denmark)

Pozzi, Giulio; Beleggia, Marco; Kasama, Takeshi

2014-01-01

The mapping of static electric and magnetic fields using electron probes with a resolution and sensitivity that are sufficient to reveal nanoscale features in materials requires the use of phase-sensitive methods such as the shadow technique, coherent Foucault imaging and the Transport of Intensi......) the model-independent determination of the locations and magnitudes of field sources (electric charges and magnetic dipoles) directly from electron holographic data.......The mapping of static electric and magnetic fields using electron probes with a resolution and sensitivity that are sufficient to reveal nanoscale features in materials requires the use of phase-sensitive methods such as the shadow technique, coherent Foucault imaging and the Transport of Intensity...... on theoretical models that form the basis of the quantitative interpretation of electron holographic data. We review the application of electron holography to a variety of samples (including electric fields associated with p–n junctions in semiconductors, quantized magnetic flux in superconductors...

An MLC calibration method using a detector array

International Nuclear Information System (INIS)

Simon, Thomas A.; Kahler, Darren; Simon, William E.; Fox, Christopher; Li, Jonathan; Palta, Jatinder; Liu, Chihray

2009-01-01

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.

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.

Research on the calibration methods of the luminance parameter of radiation luminance meters

Science.gov (United States)

Cheng, Weihai; Huang, Biyong; Lin, Fangsheng; Li, Tiecheng; Yin, Dejin; Lai, Lei

2017-10-01

This paper introduces standard diffusion reflection white plate method and integrating sphere standard luminance source method to calibrate the luminance parameter. The paper compares the effects of calibration results by using these two methods through principle analysis and experimental verification. After using two methods to calibrate the same radiation luminance meter, the data obtained verifies the testing results of the two methods are both reliable. The results show that the display value using standard white plate method has fewer errors and better reproducibility. However, standard luminance source method is more convenient and suitable for on-site calibration. Moreover, standard luminance source method has wider range and can test the linear performance of the instruments.

Assessment of a dynamic reference material for calibration of full-field measurement systems

Science.gov (United States)

Hack, Erwin; Feligiotti, Mara; Davighi, Andrea; Whelan, Maurice; Wang, Weizhuo V.; Patterson, Eann A.

2012-10-01

For holography and speckle interferometry the calibration of the sensitivity is a must, because illumination and observation directions vary across the field of view. A numerical estimate or a static calibration using rigid body motions is standard, and reference materials exist for static strain calibration. Recently, reference materials for the dynamic calibration of optical instruments of displacement and strain measurement were designed and prototypes were manufactured in the European FP7 project ADVISE. We review the properties of the reference material and the concept of traceability for the field of displacement values by using a calibrated single point transducer. The mode shape is assessed using out-of-plane DSPI, Finite Element Analysis as well as analytic solutions of the plate vibration. We present measurements using stroboscopic DSPI on the reference material under acoustic excitation and compare the measured mode shapes to the ones predicted by FE analysis. We apply different comparison methodologies based on point-by-point deviations and on decomposition of the mode shapes into a set of orthogonal basis functions. The latter method is well suited to assess stability and reproducibility of a mode shape. Finally, the deviations are used to estimate the reference material uncertainty which is an essential parameter for determining the calibration uncertainty. Uncertainty contributions of the DSPI set-up are taken into account. To conclude, the application area and limitations of the reference material are discussed.

A flexible calibration method for laser displacement sensors based on a stereo-target

International Nuclear Information System (INIS)

Zhang, Jie; Sun, Junhua; Liu, Zhen; Zhang, Guangjun

2014-01-01

Laser displacement sensors (LDSs) are widely used in online measurement owing to their characteristics of non-contact, high measurement speed, etc. However, existing calibration methods for LDSs based on the traditional triangulation measurement model are time-consuming and tedious to operate. In this paper, a calibration method for LDSs based on a vision measurement model of the LDS is presented. According to the constraint relationships of the model parameters, the calibration is implemented by freely moving a stereo-target at least twice in the field of view of the LDS. Both simulation analyses and real experiments were conducted. Experimental results demonstrate that the calibration method achieves an accuracy of 0.044 mm within the measurement range of about 150 mm. Compared to traditional calibration methods, the proposed method has no special limitation on the relative position of the LDS and the target. The linearity approximation of the measurement model in the calibration is not needed, and thus the measurement range is not limited in the linearity range. It is easy and quick to implement the calibration for the LDS. The method can be applied in wider fields. (paper)

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.

Calibration method for projector-camera-based telecentric fringe projection profilometry system.

Science.gov (United States)

Liu, Haibo; Lin, Huijing; Yao, Linshen

2017-12-11

By combining a fringe projection setup with a telecentric lens, a fringe pattern could be projected and imaged within a small area, making it possible to measure the three-dimensional (3D) surfaces of micro-components. This paper focuses on the flexible calibration of the fringe projection profilometry (FPP) system using a telecentric lens. An analytical telecentric projector-camera calibration model is introduced, in which the rig structure parameters remain invariant for all views, and the 3D calibration target can be located on the projector image plane with sub-pixel precision. Based on the presented calibration model, a two-step calibration procedure is proposed. First, the initial parameters, e.g., the projector-camera rig, projector intrinsic matrix, and coordinates of the control points of a 3D calibration target, are estimated using the affine camera factorization calibration method. Second, a bundle adjustment algorithm with various simultaneous views is applied to refine the calibrated parameters, especially the rig structure parameters and coordinates of the control points forth 3D target. Because the control points are determined during the calibration, there is no need for an accurate 3D reference target, whose is costly and extremely difficult to fabricate, particularly for tiny objects used to calibrate the telecentric FPP system. Real experiments were performed to validate the performance of the proposed calibration method. The test results showed that the proposed approach is very accurate and reliable.

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...

A semi-automatic calibration method for seismic arrays applied to an Alaskan array

Science.gov (United States)

Lindquist, K. G.; Tibuleac, I. M.; Hansen, R. A.

2001-12-01

Well-calibrated, small (less than 22 km) aperture seismic arrays are of great importance for event location and characterization. We have implemented the crosscorrelation method of Tibuleac and Herrin (Seis. Res. Lett. 1997) as a semi-automatic procedure, applicable to any seismic array. With this we are able to process thousands of phases with several days of computer time on a Sun Blade 1000 workstation. Complicated geology beneath elements and elevation differences amonst the array stations made station corrections necessary. 328 core phases (including PcP, PKiKP, PKP, PKKP) were used in order to determine the static corrections. To demonstrate this application and method, we have analyzed P and PcP arrivals at the ILAR array (Eielson, Alaska) between years 1995-2000. The arrivals were picked by PIDC, for events (mb>4.0) well located by the USGS. We calculated backazimuth and horizontal velocity residuals for all events. We observed large backazimuth residuals for regional and near-regional phases. We are discussing the possibility of a dipping Moho (strike E-W, dip N) beneath the array versus other local structure that would produce the residuals.

AN IMPROVED INTERFEROMETRIC CALIBRATION METHOD BASED ON INDEPENDENT PARAMETER DECOMPOSITION

Directory of Open Access Journals (Sweden)

J. Fan

2018-04-01

Full Text Available Interferometric SAR is sensitive to earth surface undulation. The accuracy of interferometric parameters plays a significant role in precise digital elevation model (DEM. The interferometric calibration is to obtain high-precision global DEM by calculating the interferometric parameters using ground control points (GCPs. However, interferometric parameters are always calculated jointly, making them difficult to decompose precisely. In this paper, we propose an interferometric calibration method based on independent parameter decomposition (IPD. Firstly, the parameters related to the interferometric SAR measurement are determined based on the three-dimensional reconstruction model. Secondly, the sensitivity of interferometric parameters is quantitatively analyzed after the geometric parameters are completely decomposed. Finally, each interferometric parameter is calculated based on IPD and interferometric calibration model is established. We take Weinan of Shanxi province as an example and choose 4 TerraDEM-X image pairs to carry out interferometric calibration experiment. The results show that the elevation accuracy of all SAR images is better than 2.54 m after interferometric calibration. Furthermore, the proposed method can obtain the accuracy of DEM products better than 2.43 m in the flat area and 6.97 m in the mountainous area, which can prove the correctness and effectiveness of the proposed IPD based interferometric calibration method. The results provide a technical basis for topographic mapping of 1 : 50000 and even larger scale in the flat area and mountainous area.

Innovative Calibration Method for System Level Simulation Models of Internal Combustion Engines

Directory of Open Access Journals (Sweden)

Ivo Prah

2016-09-01

Full Text Available The paper outlines a procedure for the computer-controlled calibration of the combined zero-dimensional (0D and one-dimensional (1D thermodynamic simulation model of a turbocharged internal combustion engine (ICE. The main purpose of the calibration is to determine input parameters of the simulation model in such a way as to achieve the smallest difference between the results of the measurements and the results of the numerical simulations with minimum consumption of the computing time. An innovative calibration methodology is based on a novel interaction between optimization methods and physically based methods of the selected ICE sub-systems. Therein physically based methods were used for steering the division of the integral ICE to several sub-models and for determining parameters of selected components considering their governing equations. Innovative multistage interaction between optimization methods and physically based methods allows, unlike the use of well-established methods that rely only on the optimization techniques, for successful calibration of a large number of input parameters with low time consumption. Therefore, the proposed method is suitable for efficient calibration of simulation models of advanced ICEs.

Standardization of calibration method of whole-body counter. 1. Calibration by using anthropometric phantoms

International Nuclear Information System (INIS)

Ishikawa, Tetsuo; Matsumoto, Masaki; Uchiyama, Masafumi; Kobayashi, Sadayoshi; Mizushita, Seiichi.

1995-01-01

To standardize the calibration methods of whole-body counters, three anthropometric phantoms were manufactured based on dozens of Japanese average value of body size data. Using these phantoms, the calibrations of some whole-body counters were carried out and the comparison of counting efficiency between anthropometric phantoms and block phantoms, which used to be used for the calibration of whole-body counters generally, was implemented. Five whole-body counters, one scanning system, two stationary systems and two chair systems, were used for this study. The following results were derived: As an example, in NIRS scanning system, the counting efficiency of anthropometric phantom of 162cm height was 12.7% greater than that of block phantom of the same height. This means 137 Cs body burdens in adult men used to be estimated with the excess of about 10%. Body burdens tended to be estimated excessively in adult because the difference of counting efficiency between anthropometric phantom and block phantom increases with increase of height. To standardize body burden data measured with various whole-body counters, the calibration of each whole-body counter should be conducted using anthropometric phantoms and phantoms which used to be used for the calibration of that whole-body counter. (author)

A novel calibration method for non-orthogonal shaft laser theodolite measurement system

Energy Technology Data Exchange (ETDEWEB)

Wu, Bin, E-mail: wubin@tju.edu.cn, E-mail: xueting@tju.edu.cn; Yang, Fengting; Ding, Wen [State Key Laboratory of Precision Measuring Technology and Instruments, Tianjin University, Tianjin 300072 (China); Xue, Ting, E-mail: wubin@tju.edu.cn, E-mail: xueting@tju.edu.cn [College of Electrical Engineering and Automation, Tianjin Key Laboratory of Process Measurement and Control, Tianjin University, Tianjin 300072 (China)

2016-03-15

Non-orthogonal shaft laser theodolite (N-theodolite) is a new kind of large-scale metrological instrument made up by two rotary tables and one collimated laser. There are three axes for an N-theodolite. According to naming conventions in traditional theodolite, rotary axes of two rotary tables are called as horizontal axis and vertical axis, respectively, and the collimated laser beam is named as sight axis. And the difference between N-theodolite and traditional theodolite is obvious, since the former one with no orthogonal and intersecting accuracy requirements. So the calibration method for traditional theodolite is no longer suitable for N-theodolite, while the calibration method applied currently is really complicated. Thus this paper introduces a novel calibration method for non-orthogonal shaft laser theodolite measurement system to simplify the procedure and to improve the calibration accuracy. A simple two-step process, calibration for intrinsic parameters and for extrinsic parameters, is proposed by the novel method. And experiments have shown its efficiency and accuracy.

Effect of cantilever geometry on the optical lever sensitivities and thermal noise method of the atomic force microscope.

Science.gov (United States)

Sader, John E; Lu, Jianing; Mulvaney, Paul

2014-11-01

Calibration of the optical lever sensitivities of atomic force microscope (AFM) cantilevers is especially important for determining the force in AFM measurements. These sensitivities depend critically on the cantilever mode used and are known to differ for static and dynamic measurements. Here, we calculate the ratio of the dynamic and static sensitivities for several common AFM cantilevers, whose shapes vary considerably, and experimentally verify these results. The dynamic-to-static optical lever sensitivity ratio is found to range from 1.09 to 1.41 for the cantilevers studied - in stark contrast to the constant value of 1.09 used widely in current calibration studies. This analysis shows that accuracy of the thermal noise method for the static spring constant is strongly dependent on cantilever geometry - neglect of these dynamic-to-static factors can induce errors exceeding 100%. We also discuss a simple experimental approach to non-invasively and simultaneously determine the dynamic and static spring constants and optical lever sensitivities of cantilevers of arbitrary shape, which is applicable to all AFM platforms that have the thermal noise method for spring constant calibration.

Standard practice of calibration of force-measuring instruments for verifying the force indication of testing machines

CERN Document Server

American Society for Testing and Materials. Philadelphia

2006-01-01

1.1 The purpose of this practice is to specify procedures for the calibration of force-measuring instruments. Procedures are included for the following types of instruments: 1.1.1 Elastic force-measuring instruments, and 1.1.2 Force-multiplying systems, such as balances and small platform scales. Note 1Verification by deadweight loading is also an acceptable method of verifying the force indication of a testing machine. Tolerances for weights for this purpose are given in Practices E 4; methods for calibration of the weights are given in NIST Technical Note 577, Methods of Calibrating Weights for Piston Gages. 1.2 The values stated in SI units are to be regarded as the standard. Other metric and inch-pound values are regarded as equivalent when required. 1.3 This practice is intended for the calibration of static force measuring instruments. It is not applicable for dynamic or high speed force calibrations, nor can the results of calibrations performed in accordance with this practice be assumed valid for...

Calibration of discrete element model parameters: soybeans

Science.gov (United States)

Ghodki, Bhupendra M.; Patel, Manish; Namdeo, Rohit; Carpenter, Gopal

2018-05-01

Discrete element method (DEM) simulations are broadly used to get an insight of flow characteristics of granular materials in complex particulate systems. DEM input parameters for a model are the critical prerequisite for an efficient simulation. Thus, the present investigation aims to determine DEM input parameters for Hertz-Mindlin model using soybeans as a granular material. To achieve this aim, widely acceptable calibration approach was used having standard box-type apparatus. Further, qualitative and quantitative findings such as particle profile, height of kernels retaining the acrylic wall, and angle of repose of experiments and numerical simulations were compared to get the parameters. The calibrated set of DEM input parameters includes the following (a) material properties: particle geometric mean diameter (6.24 mm); spherical shape; particle density (1220 kg m^{-3} ), and (b) interaction parameters such as particle-particle: coefficient of restitution (0.17); coefficient of static friction (0.26); coefficient of rolling friction (0.08), and particle-wall: coefficient of restitution (0.35); coefficient of static friction (0.30); coefficient of rolling friction (0.08). The results may adequately be used to simulate particle scale mechanics (grain commingling, flow/motion, forces, etc) of soybeans in post-harvest machinery and devices.

Static and Dynamic Strain Monitoring of Reinforced Concrete Components through Embedded Carbon Nanotube Cement-Based Sensors

Directory of Open Access Journals (Sweden)

Antonella D’Alessandro

2017-01-01

Full Text Available The paper presents a study on the use of cement-based sensors doped with carbon nanotubes as embedded smart sensors for static and dynamic strain monitoring of reinforced concrete (RC elements. Such novel sensors can be used for the monitoring of civil infrastructures. Because they are fabricated from a structural material and are easy to utilize, these sensors can be integrated into structural elements for monitoring of different types of constructions during their service life. Despite the scientific attention that such sensors have received in recent years, further research is needed to understand (i the repeatability and accuracy of sensors’ behavior over a meaningful number of sensors, (ii testing configurations and calibration methods, and (iii the sensors’ ability to provide static and dynamic strain measurements when actually embedded in RC elements. To address these research needs, this paper presents a preliminary characterization of the self-sensing capabilities and the dynamic properties of a meaningful number of cement-based sensors and studies their application as embedded sensors in a full-scale RC beam. Results from electrical and electromechanical tests conducted on small and full-scale specimens using different electrical measurement methods confirm that smart cement-based sensors show promise for both static and vibration-based structural health monitoring applications of concrete elements but that calibration of each sensor seems to be necessary.

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...

Pitot pressure measurements in flow fields behind circular-arc nozzles with exhaust jets at subsonic free-stream Mach numbers. [langley 16 foot transonic tunnel

Science.gov (United States)

Mason, M. L.; Putnam, L. E.

1979-01-01

The flow field behind a circular arc nozzle with exhaust jet was studied at subsonic free stream Mach numbers. A conical probe was used to measure the pitot pressure in the jet and free stream regions. Pressure data were recorded for two nozzle configurations at nozzle pressure ratios of 2.0, 2.9, and 5.0. At each set of test conditions, the probe was traversed from the jet center line into the free stream region at seven data acquisition stations. The survey began at the nozzle exit and extended downstream at intervals. The pitot pressure data may be applied to the evaluation of computational flow field models, as illustrated by a comparison of the flow field data with results of inviscid jet plume theory.

A New Time Calibration Method for Switched-capacitor-array-based Waveform Samplers.

Science.gov (United States)

Kim, H; Chen, C-T; Eclov, N; Ronzhin, A; Murat, P; Ramberg, E; Los, S; Moses, W; Choong, W-S; Kao, C-M

2014-12-11

We have developed a new time calibration method for the DRS4 waveform sampler that enables us to precisely measure the non-uniform sampling interval inherent in the switched-capacitor cells of the DRS4. The method uses the proportionality between the differential amplitude and sampling interval of adjacent switched-capacitor cells responding to a sawtooth-shape pulse. In the experiment, a sawtooth-shape pulse with a 40 ns period generated by a Tektronix AWG7102 is fed to a DRS4 evaluation board for calibrating the sampling intervals of all 1024 cells individually. The electronic time resolution of the DRS4 evaluation board with the new time calibration is measured to be ~2.4 ps RMS by using two simultaneous Gaussian pulses with 2.35 ns full-width at half-maximum and applying a Gaussian fit. The time resolution dependencies on the time difference with the new time calibration are measured and compared to results obtained by another method. The new method could be applicable for other switched-capacitor-array technology-based waveform samplers for precise time calibration.

Calibration of groundwater vulnerability mapping using the generalized reduced gradient method.

Science.gov (United States)

Elçi, Alper

2017-12-01

Groundwater vulnerability assessment studies are essential in water resources management. Overlay-and-index methods such as DRASTIC are widely used for mapping of groundwater vulnerability, however, these methods mainly suffer from a subjective selection of model parameters. The objective of this study is to introduce a calibration procedure that results in a more accurate assessment of groundwater vulnerability. The improvement of the assessment is formulated as a parameter optimization problem using an objective function that is based on the correlation between actual groundwater contamination and vulnerability index values. The non-linear optimization problem is solved with the generalized-reduced-gradient (GRG) method, which is numerical algorithm based optimization method. To demonstrate the applicability of the procedure, a vulnerability map for the Tahtali stream basin is calibrated using nitrate concentration data. The calibration procedure is easy to implement and aims the maximization of correlation between observed pollutant concentrations and groundwater vulnerability index values. The influence of each vulnerability parameter in the calculation of the vulnerability index is assessed by performing a single-parameter sensitivity analysis. Results of the sensitivity analysis show that all factors are effective on the final vulnerability index. Calibration of the vulnerability map improves the correlation between index values and measured nitrate concentrations by 19%. The regression coefficient increases from 0.280 to 0.485. It is evident that the spatial distribution and the proportions of vulnerability class areas are significantly altered with the calibration process. Although the applicability of the calibration method is demonstrated on the DRASTIC model, the applicability of the approach is not specific to a certain model and can also be easily applied to other overlay-and-index methods. Copyright © 2017 Elsevier B.V. All rights reserved.

A calibration and data assimilation method using the Bayesian MARS emulator

International Nuclear Information System (INIS)

Stripling, H.F.; McClarren, R.G.; Kuranz, C.C.; Grosskopf, M.J.; Rutter, E.; Torralva, B.R.

2013-01-01

Highlights: ► We outline a transparent, flexible method for the calibration of uncertain inputs to computer models. ► We account for model, data, emulator, and measurement uncertainties. ► The method produces improved predictive results, which are validated using leave one-out experiments. ► Our implementation leverages the Bayesian MARS emulator, but any emulator may be substituted. -- Abstract: We present a method for calibrating the uncertain inputs to a computer model using available experimental data. The goal of the procedure is to estimate the posterior distribution of the uncertain inputs such that when samples from the posterior are used as inputs to future model runs, the model is more likely to replicate (or predict) the experimental response. The calibration is performed by sampling the space of the uncertain inputs, using the computer model (or, more likely, an emulator for the computer model) to assign weights to the samples, and applying the weights to produce the posterior distributions and generate predictions of new experiments with confidence bounds. The method is similar to Metropolis–Hastings calibration methods with independently sampled updates, except that we generate samples beforehand and replace the candidate acceptance routine with a weighting scheme. We apply our method to the calibration of a Hyades 2D model of laser energy deposition in beryllium. We employ a Bayesian Multivariate Adaptive Regression Splines (BMARS) emulator as a surrogate for Hyades 2D. We treat a range of uncertainties in our application, including uncertainties in the experimental inputs, experimental measurement error, and systematic experimental timing errors. The resulting posterior distributions agree with our existing intuition, and we validate the results by performing a series of leave-one-out predictions. We find that the calibrated predictions are considerably more accurate and less uncertain than blind sampling of the forward model alone.

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 Overhau...

Application of the cause-consequence diagram method to static systems

International Nuclear Information System (INIS)

Andrews, J.D.; Ridley, L.M.

2002-01-01

In the last 30 years, various mathematical models have been used to identify the effect of component failures on the performance of a system. The most frequently used technique for system reliability assessment is Fault Tree Analysis (FTA) and a large proportion of its popularity can be attributed to the fact that it provides a very good documentation of the way that the system failure logic was developed. Exact quantification of the fault tree, however, can be problematic for very large systems and in such situations, approximations can be used. Alternatively, an exact result can be obtained via the conversion of the fault tree into a binary decision diagram (BDD). The BDD, however, loses all failure logic documentation during the conversion process. This paper outlines the use of the cause-consequence diagram method as a tool for system risk and reliability analysis. As with the FTA method, the cause-consequence diagram documents the failure logic of the system. In addition to this the cause-consequence diagram produces the exact failure probability in a very efficient calculation procedure. The cause-consequence diagram technique has been applied to a static system and shown to yield the same result as those produced by the solution of the equivalent fault tree and BDD. On the basis of this general rules have been devised for the correct construction of the cause-consequence diagram given a static system. The use of the cause-consequence method in this manner has significant implications in terms of efficiency of the reliability analysis and can be shown to have benefits for static systems

PLEIADES ABSOLUTE CALIBRATION : INFLIGHT CALIBRATION SITES AND METHODOLOGY

Directory of Open Access Journals (Sweden)

S. Lachérade

2012-07-01

Full Text Available 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.

Comparative study among calibration methods of clinical applicators of beta radiation

International Nuclear Information System (INIS)

Antonio, Patricia de Lara

2009-01-01

90 Sr+ 90 Y 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)

A laser sheet self-calibration method for scanning PIV

Science.gov (United States)

Knutsen, Anna N.; Lawson, John M.; Dawson, James R.; Worth, Nicholas A.

2017-10-01

Knowledge of laser sheet position, orientation, and thickness is a fundamental requirement of scanning PIV and other laser-scanning methods. This paper describes the development and evaluation of a new laser sheet self-calibration method for stereoscopic scanning PIV, which allows the measurement of these properties from particle images themselves. The approach is to fit a laser sheet model by treating particles as randomly distributed probes of the laser sheet profile, whose position is obtained via a triangulation procedure enhanced by matching particle images according to their variation in brightness over a scan. Numerical simulations and tests with experimental data were used to quantify the sensitivity of the method to typical experimental error sources and validate its performance in practice. The numerical simulations demonstrate the accurate recovery of the laser sheet parameters over range of different seeding densities and sheet thicknesses. Furthermore, they show that the method is robust to significant image noise and camera misalignment. Tests with experimental data confirm that the laser sheet model can be accurately reconstructed with no impairment to PIV measurement accuracy. The new method is more efficient and robust in comparison with the standard (self-) calibration approach, which requires an involved, separate calibration step that is sensitive to experimental misalignments. The method significantly improves the practicality of making accurate scanning PIV measurements and broadens its potential applicability to scanning systems with significant vibrations.

Medical color displays and their color calibration: investigations of various calibration methods, tools, and potential improvement in color difference ΔE

Science.gov (United States)

Roehrig, Hans; Hashmi, Syed F.; Dallas, William J.; Krupinski, Elizabeth A.; Rehm, Kelly; Fan, Jiahua

2010-08-01

Our laboratory has investigated the efficacy of a suite of color calibration and monitor profiling packages which employ a variety of color measurement sensors. Each of the methods computes gamma correction tables for the red, green and blue color channels of a monitor that attempt to: a) match a desired luminance range and tone reproduction curve; and b) maintain a target neutral point across the range of grey values. All of the methods examined here produce International Color Consortium (ICC) profiles that describe the color rendering capabilities of the monitor after calibration. Color profiles incorporate a transfer matrix that establishes the relationship between RGB driving levels and the International Commission on Illumination (CIE) XYZ (tristimulus) values of the resulting on-screen color; the matrix is developed by displaying color patches of known RGB values on the monitor and measuring the tristimulus values with a sensor. The number and chromatic distribution of color patches varies across methods and is usually not under user control. In this work we examine the effect of employing differing calibration and profiling methods on rendition of color images. A series of color patches encoded in sRGB color space were presented on the monitor using color-management software that utilized the ICC profile produced by each method. The patches were displayed on the calibrated monitor and measured with a Minolta CS200 colorimeter. Differences in intended and achieved luminance and chromaticity were computed using the CIE DE2000 color-difference metric, in which a value of ΔE = 1 is generally considered to be approximately one just noticeable difference (JND) in color. We observed between one and 17 JND's for individual colors, depending on calibration method and target. As an extension of this fundamental work1, we further improved our calibration method by defining concrete calibration parameters for the display, using the NEC wide gamut puck, and making sure

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.

A Review on Microdialysis Calibration Methods: the Theory and Current Related Efforts.

Science.gov (United States)

Kho, Chun Min; Enche Ab Rahim, Siti Kartini; Ahmad, Zainal Arifin; Abdullah, Norazharuddin Shah

2017-07-01

Microdialysis is a sampling technique first introduced in the late 1950s. Although this technique was originally designed to study endogenous compounds in animal brain, it is later modified to be used in other organs. Additionally, microdialysis is not only able to collect unbound concentration of compounds from tissue sites; this technique can also be used to deliver exogenous compounds to a designated area. Due to its versatility, microdialysis technique is widely employed in a number of areas, including biomedical research. However, for most in vivo studies, the concentration of substance obtained directly from the microdialysis technique does not accurately describe the concentration of the substance on-site. In order to relate the results collected from microdialysis to the actual in vivo condition, a calibration method is required. To date, various microdialysis calibration methods have been reported, with each method being capable to provide valuable insights of the technique itself and its applications. This paper aims to provide a critical review on various calibration methods used in microdialysis applications, inclusive of a detailed description of the microdialysis technique itself to start with. It is expected that this article shall review in detail, the various calibration methods employed, present examples of work related to each calibration method including clinical efforts, plus the advantages and disadvantages of each of the methods.

Reliably detectable flaw size for NDE methods that use calibration

Science.gov (United States)

Koshti, Ajay M.

2017-04-01

Probability of detection (POD) analysis is used in assessing reliably detectable flaw size in nondestructive evaluation (NDE). MIL-HDBK-1823 and associated mh18232 POD software gives most common methods of POD analysis. In this paper, POD analysis is applied to an NDE method, such as eddy current testing, where calibration is used. NDE calibration standards have known size artificial flaws such as electro-discharge machined (EDM) notches and flat bottom hole (FBH) reflectors which are used to set instrument sensitivity for detection of real flaws. Real flaws such as cracks and crack-like flaws are desired to be detected using these NDE methods. A reliably detectable crack size is required for safe life analysis of fracture critical parts. Therefore, it is important to correlate signal responses from real flaws with signal responses form artificial flaws used in calibration process to determine reliably detectable flaw size.

New Methods for Kinematic Modelling and Calibration of Robots

DEFF Research Database (Denmark)

Søe-Knudsen, Rune

2014-01-01

the accuracy in an easy and accessible way. The required equipment is accessible, since the cost is held to a minimum and can be made with conventional processing equipment. Our first method calibrates the kinematics of a robot using known relative positions measured with the robot itself and a plate...... with holes matching the robot tool flange. The second method calibrates the kinematics using two robots. This method allows the robots to carry out the collection of measurements and the adjustment, by themselves, after the robots have been connected. Furthermore, we also propose a method for restoring......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 maintain...

Misalignment calibration of geomagnetic vector measurement system using parallelepiped frame rotation method

International Nuclear Information System (INIS)

Pang, Hongfeng; Zhu, XueJun; Pan, Mengchun; Zhang, Qi; Wan, Chengbiao; Luo, Shitu; Chen, Dixiang; Chen, Jinfei; Li, Ji; Lv, Yunxiao

2016-01-01

Misalignment error is one key factor influencing the measurement accuracy of geomagnetic vector measurement system, which should be calibrated with the difficulties that sensors measure different physical information and coordinates are invisible. A new misalignment calibration method by rotating a parallelepiped frame is proposed. Simulation and experiment result show the effectiveness of calibration method. The experimental system mainly contains DM-050 three-axis fluxgate magnetometer, INS (inertia navigation system), aluminium parallelepiped frame, aluminium plane base. Misalignment angles are calculated by measured data of magnetometer and INS after rotating the aluminium parallelepiped frame on aluminium plane base. After calibration, RMS error of geomagnetic north, vertical and east are reduced from 349.441 nT, 392.530 nT and 562.316 nT to 40.130 nT, 91.586 nT and 141.989 nT respectively. - Highlights: • A new misalignment calibration method by rotating a parallelepiped frame is proposed. • It does not need to know sensor attitude information or local dip angle. • The calibration system attitude change angle is not strictly required. • It can be widely used when sensors measure different physical information. • Geomagnetic vector measurement error is reduced evidently.

Misalignment calibration of geomagnetic vector measurement system using parallelepiped frame rotation method

Energy Technology Data Exchange (ETDEWEB)

Pang, Hongfeng [Academy of Equipment, Beijing 101416 (China); College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha 410073 (China); Zhu, XueJun, E-mail: zhuxuejun1990@126.com [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha 410073 (China); Pan, Mengchun; Zhang, Qi; Wan, Chengbiao; Luo, Shitu; Chen, Dixiang; Chen, Jinfei; Li, Ji; Lv, Yunxiao [College of Mechatronics Engineering and Automation, National University of Defense Technology, Changsha 410073 (China)

2016-12-01

Misalignment error is one key factor influencing the measurement accuracy of geomagnetic vector measurement system, which should be calibrated with the difficulties that sensors measure different physical information and coordinates are invisible. A new misalignment calibration method by rotating a parallelepiped frame is proposed. Simulation and experiment result show the effectiveness of calibration method. The experimental system mainly contains DM-050 three-axis fluxgate magnetometer, INS (inertia navigation system), aluminium parallelepiped frame, aluminium plane base. Misalignment angles are calculated by measured data of magnetometer and INS after rotating the aluminium parallelepiped frame on aluminium plane base. After calibration, RMS error of geomagnetic north, vertical and east are reduced from 349.441 nT, 392.530 nT and 562.316 nT to 40.130 nT, 91.586 nT and 141.989 nT respectively. - Highlights: • A new misalignment calibration method by rotating a parallelepiped frame is proposed. • It does not need to know sensor attitude information or local dip angle. • The calibration system attitude change angle is not strictly required. • It can be widely used when sensors measure different physical information. • Geomagnetic vector measurement error is reduced evidently.

FEM simulation of static loading test of the Omega beam

Science.gov (United States)

Bílý, Petr; Kohoutková, Alena; Jedlinský, Petr

2017-09-01

The paper deals with a FEM simulation of static loading test of the Omega beam. Omega beam is a precast prestressed high-performance concrete element with the shape of Greek letter omega. Omega beam was designed as a self-supporting permanent formwork member for construction of girder bridges. FEM program ATENA Science was exploited for simulation of load-bearing test of the beam. The numerical model was calibrated using the data from both static loading test and tests of material properties. Comparison of load-displacement diagrams obtained from the experiment and the model was conducted. Development of cracks and crack patterns were compared. Very good agreement of experimental data and the FEM model was reached. The calibrated model can be used for design of optimized Omega beams in the future without the need of expensive loading tests. The calibrated material model can be also exploited in other types of FEM analyses of bridges constructed with the use of Omega beams, such as limit state analysis, optimization of shear connectors, prediction of long-term deflections or prediction of crack development.

SU-E-J-221: Advantages of a New Surface Imaging Calibration Method for SRS Treatments

International Nuclear Information System (INIS)

Paxton, A; Manger, R; Pawlicki, T; Kim, G

2014-01-01

Purpose: The present calibration method used for the AlignRT surface imaging system relies on the placement of a calibration plate at the linac isocenter using isocenter surrogates (crosshairs, room lasers, etc.). This work investigated the potential advantages of a new calibration method that shifts the AlignRT isocenter to be coincident with the linac MV beam isocenter. Methods: To quantify the potential uncertainties associated with the present calibration method for SRS treatments, the calibration plate was intentionally shifted away from isocenter +/−3mm in the longitudinal and lateral directions and +/−1mm in the longitudinal, lateral, and vertical directions. A head phantom was placed in a mock SRS treatment position and monitored with the AlignRT system. The AlignRT-indicated offsets were recorded at 270, 315, 0, 45, and 90° couch angles for each intentional calibration misalignment. The new isocenter calibration was applied after each misalignment, and the measurements were repeated and compared to the previous results. Results: With intentional longitudinal and lateral shifts of +/−3mm and +/−1mm in the calibration plate, the average indicated offsets at couch rotations of +/−90° were 4.3mm and 1.6mm, respectively. This was in agreement with the theoretical offset of sqrt(2)*(intentional shift of the calibration plate). Since vertical shifts were along the rotation axis of the couch, these shifts had little effect on the offsets with changing couch angle. When the new calibration was applied, the indicated offsets were all within 0.5mm for all couch angles. These offsets were in agreement with the known magnitude of couch walkout. Conclusion: The potential pitfalls of the present calibration method have been established, and the advantages of the new calibration method have been demonstrated. This new calibration method effectively removes the potential miscalibration artifacts of the present calibration method, giving the AlignRT user more

K-edge energy-based calibration method for photon counting detectors

Science.gov (United States)

Ge, Yongshuai; Ji, Xu; Zhang, Ran; Li, Ke; Chen, Guang-Hong

2018-01-01

In recent years, potential applications of energy-resolved photon counting detectors (PCDs) in the x-ray medical imaging field have been actively investigated. Unlike conventional x-ray energy integration detectors, PCDs count the number of incident x-ray photons within certain energy windows. For PCDs, the interactions between x-ray photons and photoconductor generate electronic voltage pulse signals. The pulse height of each signal is proportional to the energy of the incident photons. By comparing the pulse height with the preset energy threshold values, x-ray photons with specific energies are recorded and sorted into different energy bins. To quantitatively understand the meaning of the energy threshold values, and thus to assign an absolute energy value to each energy bin, energy calibration is needed to establish the quantitative relationship between the threshold values and the corresponding effective photon energies. In practice, the energy calibration is not always easy, due to the lack of well-calibrated energy references for the working energy range of the PCDs. In this paper, a new method was developed to use the precise knowledge of the characteristic K-edge energy of materials to perform energy calibration. The proposed method was demonstrated using experimental data acquired from three K-edge materials (viz., iodine, gadolinium, and gold) on two different PCDs (Hydra and Flite, XCounter, Sweden). Finally, the proposed energy calibration method was further validated using a radioactive isotope (Am-241) with a known decay energy spectrum.

Noninvasive method for the calibration of the peak voltage (kVp) meters

International Nuclear Information System (INIS)

Macedo, E.M.; Navarro, M.V.T.; Pereira, L.; Garcia, I.F.M.; Navarro, V.C.C.

2015-01-01

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)

Local distribution of wall static pressure and heat transfer on a rough flat plate impinged by a slot air jet

Science.gov (United States)

Meda, Adimurthy; Katti, Vadiraj V.

2017-08-01

The present work experimentally investigates the local distribution of wall static pressure and the heat transfer coefficient on a rough flat plate impinged by a slot air jet. The experimental parameters include, nozzle-to-plate spacing (Z /D h = 0.5-10.0), axial distance from stagnation point ( x/D h ), size of detached rib ( b = 4-12 mm) and Reynolds number ( Re = 2500-20,000). The wall static pressure on the surface is recorded using a Pitot tube and a differential pressure transmitter. Infrared thermal imaging technique is used to capture the temperature distribution on the target surface. It is observed that, the maximum wall static pressure occurs at the stagnation point ( x/D h = 0) for all nozzle-to-plate spacing ( Z/D h ) and rib dimensions studied. Coefficient of wall static pressure ( C p ) decreases monotonically with x/D h . Sub atmospheric pressure is evident in the detached rib configurations for jet to plate spacing up to 6.0 for all ribs studied. Sub atmospheric region is stronger at Z/D h = 0.5 due to the fluid accelerating under the rib. As nozzle to plate spacing ( Z/D h ) increases, the sub-atmospheric region becomes weak and vanishes gradually. Reasonable enhancement in both C p as well as Nu is observed for the detached rib configuration. Enhancement is found to decrease with the increase in the rib width. The results of the study can be used in optimizing the cooling system design.

Neutron kinetics of fluid-fuel systems by the quasi-static method

International Nuclear Information System (INIS)

Dulla, S.; Ravetto, P.; Rostagno, M.M.

2004-01-01

The quasi-static method for the neutron kinetics of nuclear reactors is generalized for application to neutron multiplying systems fueled by a fluid multiplying material, typically a mixture of fissile molten salts. The method is derived by the application of factorization formulae for both the neutron density and the delayed precursor concentrations and the projection of the balance equations upon a weighting function. A physically meaningful weight can be assumed as the solution of the adjoint model, which is constructed for the situation considered, including delayed neutrons. The quasi-static scheme is then applied to calculations of some transients for a typical configuration of a molten-salt reactor, in a multigroup diffusion model with a one-dimensional slug-flow velocity field. The physical features associated to the motion of the fissile material are highlighted

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

International Nuclear Information System (INIS)

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

2015-01-01

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. (paper)

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....

Standardization of Laser Methods and Techniques for Vibration Measurements and Calibrations

International Nuclear Information System (INIS)

Martens, Hans-Juergen von

2010-01-01

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/s 2 ). 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.

An Expectation-Maximization Method for Calibrating Synchronous Machine Models

Energy Technology Data Exchange (ETDEWEB)

Meng, Da; Zhou, Ning; Lu, Shuai; Lin, Guang

2013-07-21

The accuracy of a power system dynamic model is essential to its secure and efficient operation. Lower confidence in model accuracy usually leads to conservative operation and lowers asset usage. To improve model accuracy, this paper proposes an expectation-maximization (EM) method to calibrate the synchronous machine model using phasor measurement unit (PMU) data. First, an extended Kalman filter (EKF) is applied to estimate the dynamic states using measurement data. Then, the parameters are calculated based on the estimated states using maximum likelihood estimation (MLE) method. The EM method iterates over the preceding two steps to improve estimation accuracy. The proposed EM method’s performance is evaluated using a single-machine infinite bus system and compared with a method where both state and parameters are estimated using an EKF method. Sensitivity studies of the parameter calibration using EM method are also presented to show the robustness of the proposed method for different levels of measurement noise and initial parameter uncertainty.

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.

Hybrid Geometric Calibration Method for Multi-Platform Spaceborne SAR Image with Sparse Gcps

Science.gov (United States)

Lv, G.; Tang, X.; Ai, B.; Li, T.; Chen, Q.

2018-04-01

Geometric calibration is able to provide high-accuracy geometric coordinates of spaceborne SAR image through accurate geometric parameters in the Range-Doppler model by ground control points (GCPs). However, it is very difficult to obtain GCPs that covering large-scale areas, especially in the mountainous regions. In addition, the traditional calibration method is only used for single platform SAR images and can't support the hybrid geometric calibration for multi-platform images. To solve the above problems, a hybrid geometric calibration method for multi-platform spaceborne SAR images with sparse GCPs is proposed in this paper. First, we calibrate the master image that contains GCPs. Secondly, the point tracking algorithm is used to obtain the tie points (TPs) between the master and slave images. Finally, we calibrate the slave images using TPs as the GCPs. We take the Beijing-Tianjin- Hebei region as an example to study SAR image hybrid geometric calibration method using 3 TerraSAR-X images, 3 TanDEM-X images and 5 GF-3 images covering more than 235 kilometers in the north-south direction. Geometric calibration of all images is completed using only 5 GCPs. The GPS data extracted from GNSS receiver are used to assess the plane accuracy after calibration. The results after geometric calibration with sparse GCPs show that the geometric positioning accuracy is 3 m for TSX/TDX images and 7.5 m for GF-3 images.

Geometric calibration method for multiple head cone beam SPECT systems

International Nuclear Information System (INIS)

Rizo, Ph.; Grangeat, P.; Guillemaud, R.; Sauze, R.

1993-01-01

A method is presented for performing geometric calibration on Single Photon Emission Tomography (SPECT) cone beam systems with multiple cone beam collimators, each having its own orientation parameters. This calibration method relies on the fact that, in tomography, for each head, the relative position of the rotation axis and of the collimator does not change during the acquisition. In order to ensure the method stability, the parameters to be estimated in intrinsic parameters and extrinsic parameters are separated. The intrinsic parameters describe the acquisition geometry and the extrinsic parameters position of the detection system with respect to the rotation axis. (authors) 3 refs

Research on a high-precision calibration method for tunable lasers

Science.gov (United States)

Xiang, Na; Li, Zhengying; Gui, Xin; Wang, Fan; Hou, Yarong; Wang, Honghai

2018-03-01

Tunable lasers are widely used in the field of optical fiber sensing, but nonlinear tuning exists even for zero external disturbance and limits the accuracy of the demodulation. In this paper, a high-precision calibration method for tunable lasers is proposed. A comb filter is introduced and the real-time output wavelength and scanning rate of the laser are calibrated by linear fitting several time-frequency reference points obtained from it, while the beat signal generated by the auxiliary interferometer is interpolated and frequency multiplied to find more accurate zero crossing points, with these points being used as wavelength counters to resample the comb signal to correct the nonlinear effect, which ensures that the time-frequency reference points of the comb filter are linear. A stability experiment and a strain sensing experiment verify the calibration precision of this method. The experimental result shows that the stability and wavelength resolution of the FBG demodulation can reach 0.088 pm and 0.030 pm, respectively, using a tunable laser calibrated by the proposed method. We have also compared the demodulation accuracy in the presence or absence of the comb filter, with the result showing that the introduction of the comb filter results to a 15-fold wavelength resolution enhancement.

Method for calibration of an axial tomographic scanner

International Nuclear Information System (INIS)

Sparks, R.A.

1977-01-01

The method of calibrating an axial tomographic scanner including frame means having an opening therein in which an object to be examined is to be placed, source and detector means mounted on the frame means for directing one or more beams of penetrating radiation through the object from the source to the detector means, and means to rotate the scanner including the source and detector means about the object whereby a plurality of sets of data corresponding to the transmission or absorption by the object of a plurality of beams of penetrating radiation are collected; the calibration method comprising mounting calibration means supporting an adjustable centering member onto the frame means, positioning the adjustable centering member at approximately the center of rotation of the scanner, placing position-sensitive indicator means adjacent the approximately centered member, rotating the scanner and the calibration means mounted thereon at least one time and, if necessary, adjusting the positioning of the centering member until the centering member is coincident with the center of rotation of the scanner as determined by minimum deflection of the position-sensitive indicator means, rotating and translating the source and detector means and determining for each angular orientation of the frame means supporting the source and detector means the central position of each translational scan relative to the centered member and/or if a plurality of detectors are utilized with the detector means for each planar slice of the object being examined, the central position of each translational scan for each detector relative to the centered member

A simultaneous electron energy and dosimeter calibration method for an electron beam irradiator

International Nuclear Information System (INIS)

Tanaka, R.; Sunaga, H.; Kojima, T.

1991-01-01

In radiation processing using electron accelerators, the reproducibility of absorbed dose in the product depends not only on the variation of beam current and conveyor speed, but also on variations of other accelerator parameters. This requires routine monitoring of the beam current and the scan width, and also requires periodical calibration of routine dosimeters usually in the shape of film, electron energy, and other radiation field parameters. The electron energy calibration is important especially for food processing. The dose calibration method using partial absorption calorimeters provides only information about absorbed dose. Measurement of average electron current density provides basic information about the radiation field formed by the beam scanning and scattering at the beam window, though it does not allow direct dose calibration. The total absorption calorimeter with a thick absorber allows dose and dosimeter calibration, if the depth profile of relative dose in a reference absorber is given experimentally. It also allows accurate calibration of the average electron energy at the surface of the calorimeter core, if electron fluence received by the calorimeter is measured at the same time. This means that both electron energy and dosimeters can be simultaneously calibrated by irradiation of a combined system including the calorimeter, the detector of the electron current density meter, and a thick reference absorber for depth profile measurement of relative dose. We have developed a simple and multifunctional system using the combined calibration method for 5 MeV electron beams. The paper describes a simultaneous calibration method for electron energy and film dosimeters, and describes the electron current density meter, the total absorption calorimeter, and the characteristics of this method. (author). 13 refs, 7 figs, 3 tabs

Differences of Streptococcus mutans adhesion between artificial mouth systems: a dinamic and static methods

Directory of Open Access Journals (Sweden)

Aryan Morita

2016-06-01

Full Text Available Background: Various materials have been used for treating dental caries. Dental caries is a disease that attacks hard tissues of the teeth. The initial phase of caries is a formation of bacterial biofilm, called as dental plaque. Dental restorative materials are expected for preventing secondary caries formation initiated by dental plaque. Initial bacterial adhesion is assumed to be an important stage of dental plaque formation. Bacteria that recognize the receptor for binding to the pellicle on tooth surface are known as initial bacterial colonies. One of the bacteria that plays a role in the early stage of dental plaque formation is Streptococcus mutans (S. mutans. Artificial mouth system (AMS used in bacterial biofilm research on the oral cavity provides the real condition of oral cavity and continous and intermittent supply of nutrients for bacteria. Purpose: This study aimed to compare the profile of S. mutans bacterial adhesion as the primary etiologic agent for dental caries between using static method and using artificial mouth system, a dinamic. method (AMS. Method: The study was conducted at Faculty of Dentistry and Integrated Research and testing laboratory (LPPT in Universitas Gadjah Mada from April to August 2015. Composite resin was used as the subject of this research. Twelve composite resins with a diameter of 5 mm and a width of 2 mm were divided into two groups, namely group using static method and group using dynamic method. Static method was performed by submerging the samples into a 100µl suspension of 1.5 x 108 CFU/ml S. mutans and 200µl BHI broth. Meanwhile AMS method was carried out by placing the samples at the AMS tube drained with 20 drops/minute of bacterial suspension and sterile aquadest. After 72 hours, five samples from each group were calculated for their biofilm mass using 1% crystal violet and read by a spectrofotometer with a wavelength of 570 nm. Meanwhile, one sample from each group was taken for its

Constitutive correlations for wire-wrapped subchannel analysis under forced and mixed convection conditions. Part 1

International Nuclear Information System (INIS)

Cheng, S.K.; Todreas, N.E.

1984-08-01

A simple subchannel analysis method based on the ENERGY series of codes, ENERGY-IV, has been established for predicting the temperature field in a single isolated wire-wrapped Liquid Metal Fast Breeder Reactor (LMFBR) subassembly under steady state forced and mixed convection conditions. The ENERGY-IV is a totally empirical code employed for fast running purposes and requires well calibrated lead length averaged input parameters to achieve satisfactory predictions. These input parameters were identified to be the inlet flow split parameters, the subchannel friction factors, the interchannel mixing parameters, the conduction shape factor, and the transverse velocity at the edge gap. Experiments were performed in a 37-pin wire-wrapped rod bundle with a geometry between that of a typical LMFBR fuel subassembly and blanket subassembly for filling the gap in the available data base for the input parameters. The isokinetic extraction method for measuring subchannel velocity, the pitot-static probe for measuring pressure drop, and the salt tracer injection method for estimating the interchannel mixing, were used in these experiments

Metrology of two-phase flow: different methods

International Nuclear Information System (INIS)

Delhaye, J.M.; Galaup, J.P.; Reocreux, M.; Ricque, R.

Nine papers are presented concerning different methods of measuring two-phase flow. Some of the methods and equipment discussed include: radiation absorption, electromagnetic flowmeter, anemometry, resistance probes, phase indicating microthermocouples, optical probes, sampling methods, and pitot tubes

Quantitative fluorescence kinetic analysis of NADH and FAD in human plasma using three- and four-way calibration methods capable of providing the second-order advantage

Energy Technology Data Exchange (ETDEWEB)

Kang, Chao [School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025 (China); Wu, Hai-Long, E-mail: hlwu@hnu.edu.cn [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Zhou, Chang; Xiang, Shou-Xia; Zhang, Xiao-Hua; Yu, Yong-Jie; Yu, Ru-Qin [State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China)

2016-03-03

The metabolic coenzymes reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are the primary electron donor and acceptor respectively, participate in almost all biological metabolic pathways. This study develops a novel method for the quantitative kinetic analysis of the degradation reaction of NADH and the formation reaction of FAD in human plasma containing an uncalibrated interferent, by using three-way calibration based on multi-way fluorescence technique. In the three-way analysis, by using the calibration set in a static manner, we directly predicted the concentrations of both analytes in the mixture at any time after the start of their reactions, even in the presence of an uncalibrated spectral interferent and a varying background interferent. The satisfactory quantitative results indicate that the proposed method allows one to directly monitor the concentration of each analyte in the mixture as the function of time in real-time and nondestructively, instead of determining the concentration after the analytical separation. Thereafter, we fitted the first-order rate law to their concentration data throughout their reactions. Additionally, a four-way calibration procedure is developed as an alternative for highly collinear systems. The results of the four-way analysis confirmed the results of the three-way analysis and revealed that both the degradation reaction of NADH and the formation reaction of FAD in human plasma fit the first-order rate law. The proposed methods could be expected to provide promising tools for simultaneous kinetic analysis of multiple reactions in complex systems in real-time and nondestructively. - Highlights: • A novel three-way calibration method for the quantitative kinetic analysis of NADH and FAD in human plasma is proposed. • The method can directly monitor the concentration of each analyte in the reaction in real-time and nondestructively. • The method has the second-order advantage. • A

Quantitative fluorescence kinetic analysis of NADH and FAD in human plasma using three- and four-way calibration methods capable of providing the second-order advantage

International Nuclear Information System (INIS)

Kang, Chao; Wu, Hai-Long; Zhou, Chang; Xiang, Shou-Xia; Zhang, Xiao-Hua; Yu, Yong-Jie; Yu, Ru-Qin

2016-01-01

The metabolic coenzymes reduced nicotinamide adenine dinucleotide (NADH) and flavin adenine dinucleotide (FAD) are the primary electron donor and acceptor respectively, participate in almost all biological metabolic pathways. This study develops a novel method for the quantitative kinetic analysis of the degradation reaction of NADH and the formation reaction of FAD in human plasma containing an uncalibrated interferent, by using three-way calibration based on multi-way fluorescence technique. In the three-way analysis, by using the calibration set in a static manner, we directly predicted the concentrations of both analytes in the mixture at any time after the start of their reactions, even in the presence of an uncalibrated spectral interferent and a varying background interferent. The satisfactory quantitative results indicate that the proposed method allows one to directly monitor the concentration of each analyte in the mixture as the function of time in real-time and nondestructively, instead of determining the concentration after the analytical separation. Thereafter, we fitted the first-order rate law to their concentration data throughout their reactions. Additionally, a four-way calibration procedure is developed as an alternative for highly collinear systems. The results of the four-way analysis confirmed the results of the three-way analysis and revealed that both the degradation reaction of NADH and the formation reaction of FAD in human plasma fit the first-order rate law. The proposed methods could be expected to provide promising tools for simultaneous kinetic analysis of multiple reactions in complex systems in real-time and nondestructively. - Highlights: • A novel three-way calibration method for the quantitative kinetic analysis of NADH and FAD in human plasma is proposed. • The method can directly monitor the concentration of each analyte in the reaction in real-time and nondestructively. • The method has the second-order advantage. • A

A calibration rig for multi-component internal strain gauge balance using the new design-of-experiment (DOE) approach

Science.gov (United States)

Nouri, N. M.; Mostafapour, K.; Kamran, M.

2018-02-01

In a closed water-tunnel circuit, the multi-component strain gauge force and moment sensor (also known as balance) are generally used to measure hydrodynamic forces and moments acting on scaled models. These balances are periodically calibrated by static loading. Their performance and accuracy depend significantly on the rig and the method of calibration. In this research, a new calibration rig was designed and constructed to calibrate multi-component internal strain gauge balances. The calibration rig has six degrees of freedom and six different component-loading structures that can be applied separately and synchronously. The system was designed based on the applicability of formal experimental design techniques, using gravity for balance loading and balance positioning and alignment relative to gravity. To evaluate the calibration rig, a six-component internal balance developed by Iran University of Science and Technology was calibrated using response surface methodology. According to the results, calibration rig met all design criteria. This rig provides the means by which various methods of formal experimental design techniques can be implemented. The simplicity of the rig saves time and money in the design of experiments and in balance calibration while simultaneously increasing the accuracy of these activities.

Photometric calibration of the COMBO-17 survey with the Softassign Procrustes Matching method

Science.gov (United States)

Sheikhbahaee, Z.; Nakajima, R.; Erben, T.; Schneider, P.; Hildebrandt, H.; Becker, A. C.

2017-11-01

Accurate photometric calibration of optical data is crucial for photometric redshift estimation. We present the Softassign Procrustes Matching (SPM) method to improve the colour calibration upon the commonly used Stellar Locus Regression (SLR) method for the COMBO-17 survey. Our colour calibration approach can be categorised as a point-set matching method, which is frequently used in medical imaging and pattern recognition. We attain a photometric redshift precision Δz/(1 + zs) of better than 2 per cent. Our method is based on aligning the stellar locus of the uncalibrated stars to that of a spectroscopic sample of the Sloan Digital Sky Survey standard stars. We achieve our goal by finding a correspondence matrix between the two point-sets and applying the matrix to estimate the appropriate translations in multidimensional colour space. The SPM method is able to find the translation between two point-sets, despite the existence of noise and incompleteness of the common structures in the sets, as long as there is a distinct structure in at least one of the colour-colour pairs. We demonstrate the precision of our colour calibration method with a mock catalogue. The SPM colour calibration code is publicly available at https://neuronphysics@bitbucket.org/neuronphysics/spm.git.

Efficient Algorithm for a k-out-of-N System Reliability Modeling-Case Study: Pitot Sensors System for Aircraft Velocity

Directory of Open Access Journals (Sweden)

Wajih Ezzeddine

2017-08-01

Full Text Available The k-out-of-N system is widely applied in several industrial systems. This structure is a part of fault-tolerant systems for which both parallel and series systems are special cases. Because of the importance of industrial systems reliability determination for production and maintenance management purposes, a number of techniques and methods are incorporated to formulate and estimate its analytic expression. In this paper, an algorithm is put forward for a k-out-of-N system with identical components under information about the influence factors that affect the system efficiency. The developed approach is applied in the case of the Pitot sensors system. However, the algorithm application could be generalized for any device which during a mission is subject to environmental and operational factors that affect its degradation process.

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.

Five-hole pitot probe measurements of swirl, confinement and nozzle effects on confined turbulent flow

Science.gov (United States)

Lilley, D. G.; Scharrer, G. L.

1984-01-01

The results of a time-mean flow characterization of nonswirling and swirling inert flows in a combustor are reported. The five-hole pitot probe technique was used in axisymmetric test sections with expansion ratios of 1 and 1.5. A prominent corner recirculation zone identified in nonswirling expanding flows decreased in size with swirling flows. The presence of a downstream nozzle led to an adverse pressure gradient at the wall and a favorable gradient near the centerline. Reducing the expansion ratio reduced the central recirculation length. No significant effect was introduced in the flowfield by a gradual expansion.

Calibration of acoustic sensors in ice using the reciprocity method

Energy Technology Data Exchange (ETDEWEB)

Meures, Thomas; Bissok, Martin; Laihem, Karim; Paul, Larissa; Wiebusch, Christopher; Zierke, Simon [III. Physikalisches Institut, RWTH Aachen (Germany); Semburg, Benjamin [Bergische Universitaet Wuppertal (Germany). Fachbereich C

2010-07-01

Within the IceCube experiment at the South Pole an R and D program investigates new ways of ultra high energy neutrino detection. In particular when aiming for detector volumes of the order of 100 km{sup 3} acoustic or radio detectors are promising approaches. The acoustic detection method relies on the thermo-acoustic effect occurring when high energetic particles interact and deposit heat within a detection medium. This effect is investigated in the Aachen Acoustic Laboratory (AAL). The high energy particle interaction is simulated by a powerful pulsed Nd:YAG LASER shooting into a 3m{sup 3} tank of clear ice (or water). Eighteen acoustic sensors are situated on three rings in different depths and record the generated signals. These sensors serve as reference for later measurements of other devices. The reciprocity method, used for the absolute calibration of these sensors, is independent of an absolutely calibrated reference. This method and its application to the calibration of the AAL sensors are presented and first results are shown.

SU-F-E-19: A Novel Method for TrueBeam Jaw Calibration

Energy Technology Data Exchange (ETDEWEB)

Corns, R; Zhao, Y; Huang, V [Fraser Valley Cancer Centre - BC Cancer Agency, Surrey, BC (United Kingdom)

2016-06-15

Purpose: A simple jaw calibration method is proposed for Varian TrueBeam using an EPID-Encoder combination that gives accurate fields sizes and a homogeneous junction dose. This benefits clinical applications such as mono-isocentric half-beam block breast cancer or head and neck cancer treatment with junction/field matching. Methods: We use EPID imager with pixel size 0.392 mm × 0.392 mm to determine the radiation jaw position as measured from radio-opaque markers aligned with the crosshair. We acquire two images with different symmetric field sizes and record each individual jaw encoder values. A linear relationship between each jaw’s position and its encoder value is established, from which we predict the encoder values that produce the jaw positions required by TrueBeam’s calibration procedure. During TrueBeam’s jaw calibration procedure, we move the jaw with the pendant to set the jaw into position using the predicted encoder value. The overall accuracy is under 0.1 mm. Results: Our in-house software analyses images and provides sub-pixel accuracy to determine field centre and radiation edges (50% dose of the profile). We verified the TrueBeam encoder provides a reliable linear relationship for each individual jaw position (R{sup 2}>0.9999) from which the encoder values necessary to set jaw calibration points (1 cm and 19 cm) are predicted. Junction matching dose inhomogeneities were improved from >±20% to <±6% using this new calibration protocol. However, one technical challenge exists for junction matching, if the collimator walkout is large. Conclusion: Our new TrueBeam jaw calibration method can systematically calibrate the jaws to crosshair within sub-pixel accuracy and provides both good junction doses and field sizes. This method does not compensate for a larger collimator walkout, but can be used as the underlying foundation for addressing the walkout issue.

Calibration

International Nuclear Information System (INIS)

Greacen, E.L.; Correll, R.L.; Cunningham, R.B.; Johns, G.G.; Nicolls, K.D.

1981-01-01

Procedures common to different methods of calibration of neutron moisture meters are outlined and laboratory and field calibration methods compared. Gross errors which arise from faulty calibration techniques are described. The count rate can be affected by the dry bulk density of the soil, the volumetric content of constitutional hydrogen and other chemical components of the soil and soil solution. Calibration is further complicated by the fact that the neutron meter responds more strongly to the soil properties close to the detector and source. The differences in slope of calibration curves for different soils can be as much as 40%

Micro manometer and pitot tube for measuring the velocity distribution in a natural convection water stream between two vertical parallel plates (1961)

International Nuclear Information System (INIS)

Santon, L.; Vernier, Ph.

1961-01-01

For heat transfer studies in certain cases of cooling in swimming-pool type nuclear reactors, a knowledge of the distribution of the velocities between two heating elements is of prime importance. A Pitot tube and a micro-manometer have been developed for making these measurements on an experimental model. (authors) [fr

An accurate calibration method for accelerometer nonlinear scale factor on a low-cost three-axis turntable

International Nuclear Information System (INIS)

Pan, Jianye; Zhang, Chunxi; Cai, Qingzhong

2014-01-01

Strapdown inertial navigation system (SINS) requirements are very demanding on gyroscopes and accelerometers as well as on calibration. To improve the accuracy of SINS, high-accuracy calibration is needed. Adding the accelerometer nonlinear scale factor into the model and reducing estimation errors is essential for improving calibration methods. In this paper, the inertial navigation error model is simplified, including only velocity and tilt errors. Based on the simplified error model, the relationship between the navigation errors (the rates of change of velocity errors) and the inertial measurement unit (IMU) calibration parameters is presented. A tracking model is designed to estimate the rates of change of velocity errors. With a special calibration procedure consisting of six rotation sequences, the accelerometer nonlinear scale factor errors can be computed by the estimates of the rates of change of velocity errors. Simulation and laboratory test results show that the accelerometer nonlinear scale factor can be calibrated with satisfactory accuracy on a low-cost three-axis turntable in several minutes. The comparison with the traditional calibration method highlights the superior performance of the proposed calibration method without precise orientation control. In addition, the proposed calibration method saves a lot of time in comparison with the multi-position calibration method. (paper)

A Design Method for the Tension Side of Statically Loaded, Bolted Beam-to-Column Connections

NARCIS (Netherlands)

Zoetemeijer, P.

1974-01-01

In this paper a design method for the tension side of statically loaded, bolted beam-to-column connections is developed based on the plastic behaviour of the flanges and the bolts under the assumption that the plastification is large enough to allow the adoption of the most favourable static

Design of a Two-Step Calibration Method of Kinematic Parameters for Serial Robots

Science.gov (United States)

WANG, Wei; WANG, Lei; YUN, Chao

2017-03-01

Serial robots are used to handle workpieces with large dimensions, and calibrating kinematic parameters is one of the most efficient ways to upgrade their accuracy. Many models are set up to investigate how many kinematic parameters can be identified to meet the minimal principle, but the base frame and the kinematic parameter are indistinctly calibrated in a one-step way. A two-step method of calibrating kinematic parameters is proposed to improve the accuracy of the robot's base frame and kinematic parameters. The forward kinematics described with respect to the measuring coordinate frame are established based on the product-of-exponential (POE) formula. In the first step the robot's base coordinate frame is calibrated by the unit quaternion form. The errors of both the robot's reference configuration and the base coordinate frame's pose are equivalently transformed to the zero-position errors of the robot's joints. The simplified model of the robot's positioning error is established in second-power explicit expressions. Then the identification model is finished by the least square method, requiring measuring position coordinates only. The complete subtasks of calibrating the robot's 39 kinematic parameters are finished in the second step. It's proved by a group of calibration experiments that by the proposed two-step calibration method the average absolute accuracy of industrial robots is updated to 0.23 mm. This paper presents that the robot's base frame should be calibrated before its kinematic parameters in order to upgrade its absolute positioning accuracy.

Self-Calibration Method Based on Surface Micromaching of Light Transceiver Focal Plane for Optical Camera

Directory of Open Access Journals (Sweden)

Jin Li

2016-10-01

Full Text Available In remote sensing photogrammetric applications, inner orientation parameter (IOP calibration of remote sensing camera is a prerequisite for determining image position. However, achieving such a calibration without temporal and spatial limitations remains a crucial but unresolved issue to date. The accuracy of IOP calibration methods of a remote sensing camera determines the performance of image positioning. In this paper, we propose a high-accuracy self-calibration method without temporal and spatial limitations for remote sensing cameras. Our method is based on an auto-collimating dichroic filter combined with a surface micromachining (SM point-source focal plane. The proposed method can autonomously complete IOP calibration without the need of outside reference targets. The SM procedure is used to manufacture a light transceiver focal plane, which integrates with point sources, a splitter, and a complementary metal oxide semiconductor sensor. A dichroic filter is used to fabricate an auto-collimation light reflection element. The dichroic filter, splitter, and SM point-source focal plane are integrated into a camera to perform an integrated self-calibration. Experimental measurements confirm the effectiveness and convenience of the proposed method. Moreover, the method can achieve micrometer-level precision and can satisfactorily complete real-time calibration without temporal or spatial limitations.

A forecasting performance comparison of dynamic factor models based on static and dynamic methods

Directory of Open Access Journals (Sweden)

Marra Fabio Della

2017-03-01

Full Text Available We present a comparison of the forecasting performances of three Dynamic Factor Models on a large monthly data panel of macroeconomic and financial time series for the UE economy. The first model relies on static principal-component and was introduced by Stock and Watson (2002a, b. The second is based on generalized principal components and it was introduced by Forni, Hallin, Lippi and Reichlin (2000, 2005. The last model has been recently proposed by Forni, Hallin, Lippi and Zaffaroni (2015, 2016. The data panel is split into two parts: the calibration sample, from February 1986 to December 2000, is used to select the most performing specification for each class of models in a in- sample environment, and the proper sample, from January 2001 to November 2015, is used to compare the performances of the selected models in an out-of-sample environment. The metholodogical approach is analogous to Forni, Giovannelli, Lippi and Soccorsi (2016, but also the size of the rolling window is empirically estimated in the calibration process to achieve more robustness. We find that, on the proper sample, the last model is the most performing for the Inflation. However, mixed evidencies appear over the proper sample for the Industrial Production.

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)

Experimental facility and void fraction calibration methods for impedance probes

International Nuclear Information System (INIS)

Oliveira, Fernando L. de; Rocha, Marcelo S.

2013-01-01

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)

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...

Influence of Ultrasonic Nonlinear Propagation on Hydrophone Calibration Using Two-Transducer Reciprocity Method

Science.gov (United States)

Yoshioka, Masahiro; Sato, Sojun; Kikuchi, Tsuneo; Matsuda, Yoichi

2006-05-01

In this study, the influence of ultrasonic nonlinear propagation on hydrophone calibration by the two-transducer reciprocity method is investigated quantitatively using the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation. It is proposed that the correction for the diffraction and attenuation of ultrasonic waves used in two-transducer reciprocity calibration can be derived using the KZK equation to remove the influence of nonlinear propagation. The validity of the correction is confirmed by comparing the sensitivities calibrated by the two-transducer reciprocity method and laser interferometry.

Hot-Wire Calibration at Low Velocities: Revisiting the Vortex Shedding Method

Directory of Open Access Journals (Sweden)

Sohrab S. Sattarzadeh

2013-01-01

Full Text Available The necessity to calibrate hot-wire probes against a known velocity causes problems at low velocities, due to the inherent inaccuracy of pressure transducers at low differential pressures. The vortex shedding calibration method is in this respect a recommended technique to obtain calibration data at low velocities, due to its simplicity and accuracy. However, it has mainly been applied in a low and narrow Reynolds number range known as the laminar vortex shedding regime. Here, on the other hand, we propose to utilize the irregular vortex shedding regime and show where the probe needs to be placed with respect to the cylinder in order to obtain unambiguous calibration data.

Comparison between calibration methods of ionization chamber type pencil in greatness P_K_L

International Nuclear Information System (INIS)

Macedo, E.M.; Pereira, L.C.S.; Ferreira, M.J.; Navarro, V.C.C.; Garcia, I.F.M.; Pires, E.J.; Navarro, M.V.T.

2016-01-01

Calibration of radiation meters is indispensable on Quality Assurance Program in Radiodiagnostic procedures, mainly Computed Tomography. Thus, this study aims evaluate two calibration methods of pencil ionization chambers in terms of Kerma-length Product (P_K_L) (a direct substitution method and an indirect one, through Kerma and length measurements). The results showed a good equivalence, with minimal concordance of 98,5% between calibration factors. About uncertainties, both showed similar results (substitution 2.2% and indirect 2.3%), indicating that the last one is better, due the costs reduction to implant this calibration procedure. (author)

A new calibration method for tri-axial field sensors in strap-down navigation systems

International Nuclear Information System (INIS)

Li, Xiang; Li, Zhi

2012-01-01

This paper presents a novel calibration method for tri-axial field sensors, such as magnetometers and accelerometers, in strap-down navigation systems. Strap-down tri-axial sensors have been widely used as they have the advantages of small size and low cost, but they need to be calibrated in order to ensure their accuracy. The most commonly used calibration method for a tri-axial field sensor is based on ellipsoid fitting, which has no requirement for external references. However, the self-calibration based on ellipsoid fitting is unable to determine and compensate the mutual misalignment between different sensors in a multi-sensor system. Therefore, a novel calibration method that employs the invariance of the dot product of two constant vectors is introduced in this paper. The proposed method, which is named dot product invariance method, brings a complete solution for the error model of tri-axial field sensors, and can solve the problem of alignment in a multi-sensor system. Its effectiveness and superiority over the ellipsoid fitting method are illustrated by numerical simulations, and its application on a digital magnetic compass shows significant enhancement of the heading accuracy. (paper)

Instance Analysis for the Error of Three-pivot Pressure Transducer Static Balancing Method for Hydraulic Turbine Runner

Science.gov (United States)

Weng, Hanli; Li, Youping

2017-04-01

The working principle, process device and test procedure of runner static balancing test method by weighting with three-pivot pressure transducers are introduced in this paper. Based on an actual instance of a V hydraulic turbine runner, the error and sensitivity of the three-pivot pressure transducer static balancing method are analysed. Suggestions about improving the accuracy and the application of the method are also proposed.

Calibration Methods for a Space Borne Backscatter Lidar

NARCIS (Netherlands)

Kunz, G.J.

1996-01-01

Lidar returns from cloud decks and from the Earth's surface are useful for calibrating single scatter lidar signals from space. To this end analytical methods (forward and backward) are presented for inverting lidar waveforms in terms of the path integrated lidar retum and the transmission losses

Calibration of DEM parameters on shear test experiments using Kriging method

Science.gov (United States)

Xavier, Bednarek; Sylvain, Martin; Abibatou, Ndiaye; Véronique, Peres; Olivier, Bonnefoy

2017-06-01

Calibration of powder mixing simulation using Discrete-Element-Method is still an issue. Achieving good agreement with experimental results is difficult because time-efficient use of DEM involves strong assumptions. This work presents a methodology to calibrate DEM parameters using Efficient Global Optimization (EGO) algorithm based on Kriging interpolation method. Classical shear test experiments are used as calibration experiments. The calibration is made on two parameters - Young modulus and friction coefficient. The determination of the minimal number of grains that has to be used is a critical step. Simulations of a too small amount of grains would indeed not represent the realistic behavior of powder when using huge amout of grains will be strongly time consuming. The optimization goal is the minimization of the objective function which is the distance between simulated and measured behaviors. The EGO algorithm uses the maximization of the Expected Improvement criterion to find next point that has to be simulated. This stochastic criterion handles with the two interpolations made by the Kriging method : prediction of the objective function and estimation of the error made. It is thus able to quantify the improvement in the minimization that new simulations at specified DEM parameters would lead to.

An investigation of methods for free-field comparison calibration of measurement microphones

DEFF Research Database (Denmark)

Barrera-Figueroa, Salvador; Moreno Pescador, Guillermo; Jacobsen, Finn

2010-01-01

Free-field comparison calibration of measurement microphones requires that a calibrated reference microphone and a test microphone are exposed to the same sound pressure in a free field. The output voltages of the microphones can be measured either sequentially or simultaneously. The sequential...... method requires the sound field to have good temporal stability. The simultaneous method requires instead that the sound pressure is the same in the positions where the microphones are placed. In this paper the results of the application of the two methods are compared. A third combined method...

A novel enhanced calibration method for DSSSD detectors

Energy Technology Data Exchange (ETDEWEB)

Kaya, Levent; Vogt, Andreas; Reiter, Peter; Birkenbach, Benedikt; Hirsch, Rouven; Seidlitz, Michael; Warr, Nigel [Institut fuer Kernphysik, Universitaet zu Koeln (Germany)

2016-07-01

Double-sided silicon strip detectors (DSSSD) are employed for the detection of charged particles in low-energy nuclear physics providing position and energy information for the impinging particle. Intersecting areas of both p- and n-side strips form individual pixel segments allowing for a high detector granularity. However, due to limitation in fabrication and the response of readout electronics, the performance of different channels may vary. In order to achieve best energy information, a calibration of each p- and n-side strip with a very high precision is mandatory. DSSSD responses are analyzed employing energy correlation matrices between adjacent strips in order to determine charge-sharing and energy-loss effects. A novel calibration method is based on the fact that each event is registered simultaneously on the p- and n-side strips. A two-dimensional calibration procedure allows for a significant enhancement of the energy resolution. In this way, the performance of DSSSDs with position-dependent radiation damage is improved clearly by excluding locally damaged detector areas without losing the information of complete p- or n-side strips.

Calibration of PCB-132 Sensors in a Shock Tube

Science.gov (United States)

Berridge, Dennis C.; Schneider, Steven P.

2012-01-01

While PCB-132 sensors have proven useful for measuring second-mode instability waves in many hypersonic wind tunnels, they are currently limited by their calibration. Until now, the factory calibration has been all that was available, which is a single-point calibration at an amplitude three orders of magnitude higher than a second-mode wave. In addition, little information has been available about the frequency response or spatial resolution of the sensors, which is important for measuring high-frequency instability waves. These shortcomings make it difficult to compare measurements at different conditions and between different sensors. If accurate quantitative measurements could be performed, comparisons of the growth and breakdown of instability waves could be made in different facilities, possibly leading to a method of predicting the amplitude at which the waves break down into turbulence, improving transition prediction. A method for calibrating the sensors is proposed using a newly-built shock tube at Purdue University. This shock tube, essentially a half-scale version of the 6-Inch shock tube at the Graduate Aerospace Laboratories at Caltech, has been designed to attain a moderate vacuum in the driven section. Low driven pressures should allow the creation of very weak, yet still relatively thin shock waves. It is expected that static pressure rises within the range of second-mode amplitudes should be possible. The shock tube has been designed to create clean, planar shock waves with a laminar boundary layer to allow for accurate calibrations. Stronger shock waves can be used to identify the frequency response of the sensors out to hundreds of kilohertz.

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.

Brightness checkerboard lattice method for the calibration of the coaxial reverse Hartmann test

Science.gov (United States)

Li, Xinji; Hui, Mei; Li, Ning; Hu, Shinan; Liu, Ming; Kong, Lingqin; Dong, Liquan; Zhao, Yuejin

2018-01-01

The coaxial reverse Hartmann test (RHT) is widely used in the measurement of large aspheric surfaces as an auxiliary method for interference measurement, because of its large dynamic range, highly flexible test with low frequency of surface errors, and low cost. And the accuracy of the coaxial RHT depends on the calibration. However, the calibration process remains inefficient, and the signal-to-noise ratio limits the accuracy of the calibration. In this paper, brightness checkerboard lattices were used to replace the traditional dot matrix. The brightness checkerboard method can reduce the number of dot matrix projections in the calibration process, thus improving efficiency. An LCD screen displayed a brightness checkerboard lattice, in which the brighter checkerboard and the darker checkerboard alternately arranged. Based on the image on the detector, the relationship between the rays at certain angles and the photosensitive positions of the detector coordinates can be obtained. And a differential de-noising method can effectively reduce the impact of noise on the measurement results. Simulation and experimentation proved the feasibility of the method. Theoretical analysis and experimental results show that the efficiency of the brightness checkerboard lattices is about four times that of the traditional dot matrix, and the signal-to-noise ratio of the calibration is significantly improved.

A comparison of two methods of measuring static coefficient of friction at low normal forces: a pilot study.

Science.gov (United States)

Seo, Na Jin; Armstrong, Thomas J; Drinkaus, Philip

2009-01-01

This study compares two methods for estimating static friction coefficients for skin. In the first method, referred to as the 'tilt method', a hand supporting a flat object is tilted until the object slides. The friction coefficient is estimated as the tangent of the angle of the object at the slip. The second method estimates the friction coefficient as the pull force required to begin moving a flat object over the surface of the hand, divided by object weight. Both methods were used to estimate friction coefficients for 12 subjects and three materials (cardboard, aluminium, rubber) against a flat hand and against fingertips. No differences in static friction coefficients were found between the two methods, except for that of rubber, where friction coefficient was 11% greater for the tilt method. As with previous studies, the friction coefficients varied with contact force and contact area. Static friction coefficient data are needed for analysis and design of objects that are grasped or manipulated with the hand. The tilt method described in this study can easily be used by ergonomic practitioners to estimate static friction coefficients in the field in a timely manner.

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

Directory of Open Access Journals (Sweden)

G. Demurtas

2016-09-01

Full Text Available 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 will also overestimate (underestimate the wind speed when there is a yaw misalignment. The new method leverages the non-linearity of the spinner anemometer algorithm to find the calibration factor Fα by an optimization process that minimizes the dependency of the wind speed on the yaw misalignment. The new calibration method was found to be rather robust, with Fα values within ±2.7 % of the mean value for four successive tests at the same rotor position.

Study on dry-calibration method of ultrasonic flowmeter

International Nuclear Information System (INIS)

Ozaki, Yoshihiko; Yasuda, Hidenori.

1988-01-01

This paper describes a study on a dry-calibration method for application of an ultrasonic flowmeter to the fields such as nuclear or thermal power plants where high temperature and pressurized fluids are used in coolant or feedwater systems. For the measurement of the flow quantity using the ultrasonic flowmeter, it is important to obtain a correction coefficient of the rate of line averaged axial velocity to plane averaged axial velocity. We have developed analytical method to predict the turbulent flow profiles in the cross sections of piping including bends. The method is based on parabolic flow model and k-ε model with wall functions for the near-wall regions. The axial velocity profiles and the correction coefficients predicted by the analytical method were compared with the experimental results for water and liquid sodium in various L/D conditions. The both results were shown to be in approximate agreement within about 5% accuracy for the flow profiles and about 2% accuracy for the correction coefficients, though the piping had the 90degC bend with a very small redius of curvature. In the case of small L/D conditions, it was also shown that the reverse flow effects could not be disregarded in the predominant direction. However, the accuracy of the dry-calibration by using the analytical method was confirmed to be within about 2% as things were. (author)

Active design method for the static characteristics of a piezoelectric six-axis force/torque sensor.

Science.gov (United States)

Liu, Jun; Li, Min; Qin, Lan; Liu, Jingcheng

2014-01-02

To address the bottleneck issues of an elastic-style six-axis force/torque sensor (six-axis force sensor), this work proposes a no-elastic piezoelectric six-axis force sensor. The operating principle of the piezoelectric six-axis force sensor is analyzed, and a structural model is constructed. The static-active design theory of the piezoelectric six-axis force sensor is established, including a static analytical/mathematical model and numerical simulation model (finite element model). A piezoelectric six-axis force sensor experimental prototype is developed according to the analytical mathematical model and numerical simulation model, and selected static characteristic parameters (including sensitivity, isotropic degree and cross-coupling) are tested using this model with three approaches. The measured results are in agreement with the analytical results from the static-active design method. Therefore, this study has successfully established a foundation for further research into the piezoelectric multi-axis force sensor and an overall design approach based on static characteristics.

Comparison of measured and computed pitot pressures in a leading edge vortex from a delta wing

Science.gov (United States)

Murman, Earll M.; Powell, Kenneth G.

1987-01-01

Calculations are presented for a 75-deg swept flat plate wing tested at a freestream Mach number of 1.95 and 10 degrees angle of attack. Good agreement is found between computational data and previous experimental pitot pressure measurements in the core of the vortex, suggesting that the total pressure losses predicted by the Euler equation solvers are not errors, but realistic predictions. Data suggest that the magnitude of the total pressure loss is related to the circumferential velocity field through the vortex, and that it increases with angle of attack and varies with Mach number and sweep angle.

Improvement of Accuracy in Environmental Dosimetry by TLD Cards Using Three-dimensional Calibration Method

Directory of Open Access Journals (Sweden)

HosseiniAliabadi S. J.

2015-06-01

Full Text Available Background: The angular dependency of response for TLD cards may cause deviation from its true value on the results of environmental dosimetry, since TLDs may be exposed to radiation at different angles of incidence from the surrounding area. Objective: A 3D setting of TLD cards has been calibrated isotropically in a standard radiation field to evaluate the improvement of the accuracy of measurement for environmental dosimetry. Method: Three personal TLD cards were rectangularly placed in a cylindrical holder, and calibrated using 1D and 3D calibration methods. Then, the dosimeter has been used simultaneously with a reference instrument in a real radiation field measuring the accumulated dose within a time interval. Result: The results show that the accuracy of measurement has been improved by 6.5% using 3D calibration factor in comparison with that of normal 1D calibration method. Conclusion: This system can be utilized in large scale environmental monitoring with a higher accuracy

A new method to calibrate Lagrangian model with ASAR images for oil slick trajectory.

Science.gov (United States)

Tian, Siyu; Huang, Xiaoxia; Li, Hongga

2017-03-15

Since Lagrangian model coefficients vary with different conditions, it is necessary to calibrate the model to obtain optimal coefficient combination for special oil spill accident. This paper focuses on proposing a new method to calibrate Lagrangian model with time series of Envisat ASAR images. Oil slicks extracted from time series images form a detected trajectory of special oil slick. Lagrangian model is calibrated by minimizing the difference between simulated trajectory and detected trajectory. mean center position distance difference (MCPD) and rotation difference (RD) of Oil slicks' or particles' standard deviational ellipses (SDEs) are calculated as two evaluations. The two parameters are taken to evaluate the performance of Lagrangian transport model with different coefficient combinations. This method is applied to Penglai 19-3 oil spill accident. The simulation result with calibrated model agrees well with related satellite observations. It is suggested the new method is effective to calibrate Lagrangian model. Copyright © 2016 Elsevier Ltd. All rights reserved.

Simple method for absolute calibration of geophones, seismometers, and other inertial vibration sensors

International Nuclear Information System (INIS)

Kann, Frank van; Winterflood, John

2005-01-01

A simple but powerful method is presented for calibrating geophones, seismometers, and other inertial vibration sensors, including passive accelerometers. The method requires no cumbersome or expensive fixtures such as shaker platforms and can be performed using a standard instrument commonly available in the field. An absolute calibration is obtained using the reciprocity property of the device, based on the standard mathematical model for such inertial sensors. It requires only simple electrical measurement of the impedance of the sensor as a function of frequency to determine the parameters of the model and hence the sensitivity function. The method is particularly convenient if one of these parameters, namely the suspended mass is known. In this case, no additional mechanical apparatus is required and only a single set of impedance measurements yields the desired calibration function. Moreover, this measurement can be made with the device in situ. However, the novel and most powerful aspect of the method is its ability to accurately determine the effective suspended mass. For this, the impedance measurement is made with the device hanging from a simple spring or flexible cord (depending on the orientation of its sensitive axis). To complete the calibration, the device is weighed to determine its total mass. All the required calibration parameters, including the suspended mass, are then determined from a least-squares fit to the impedance as a function of frequency. A demonstration using both a 4.5 Hz geophone and a 1 Hz seismometer shows that the method can yield accurate absolute calibrations with an error of 0.1% or better, assuming no a priori knowledge of any parameters

From Static Output Feedback to Structured Robust Static Output Feedback: A Survey

OpenAIRE

Sadabadi , Mahdieh ,; Peaucelle , Dimitri

2016-01-01

This paper reviews the vast literature on static output feedback design for linear time-invariant systems including classical results and recent developments. In particular, we focus on static output feedback synthesis with performance specifications, structured static output feedback, and robustness. The paper provides a comprehensive review on existing design approaches including iterative linear matrix inequalities heuristics, linear matrix inequalities with rank constraints, methods with ...

Research on direct calibration method of eye-to-hand system of robot

Science.gov (United States)

Hu, Xiaoping; Xie, Ke; Peng, Tao

2013-10-01

In the position-based visual servoing control for robot, the hand-eye calibration is very important because it can affect the control precision of the system. According to the robot with eye-to-hand stereovision system, this paper proposes a direct method of hand-eye calibration. The method utilizes the triangle measuring principle to solve the coordinates in the camera coordinate system of scene point. It calculates the estimated coordinates by the hand-eye calibration equation set which indicates the transformational relation from the robot to the camera coordinate system, and then uses the error of actual and estimated coordinates to establish the objective function. Finally the method substitutes the parameters into the function repeatedly until it converged to optimize the result. The related experiment compared the measured coordinates with the actual coordinates, shows the efficiency and the precision of it.

Pitot survey of exhaust flow field of a 2-D scramjet nozzle at Mach 6 with air or freon and argon used for exhaust simulation

Science.gov (United States)

Monta, William J.

1992-01-01

A pitot-rake survey of the simulated exhaust of a half-span scramjet nozzle model was conducted in the Langley 20-Inch Mach 6 Tunnel to provide an additional data set for computational fluid dynamics (CFD) code comparisons. A wind-tunnel model was tested with a 26-tube pitot rake that could be manually positioned along the mid-semispan plane of the model. The model configuration had an external expansion surface of 20 degrees and an internal cowl expansion of 12 degrees; tests were also performed with a flow fence. Tests were conducted at a free-stream Reynolds number of approximately 6.5 x 10(exp 6) per foot and a model angle of attack of -0.75 degrees. The two exhaust gas mediums that were tested were air and a Freon 12-argon mixture. Each medium was tested at two jet total pressures at approximately 28 and 14 psia. This document presents the flow-field survey results in graphical as well as tabular form, and several observations concerning the results are discussed. The surveys reveal the major expected flow-field characteristics for each test configuration. For a 50-percent freon 12 and 50-percent argon mixture by volume (Fr-Ar), the exhaust jet pressures were slightly higher than those for air. The addition of a flow fence slightly raised the pitot pressure for the Fr-Ar mixture, but it produced little change for air. For the Fr-Ar exhaust, the plume was larger and the region between the shock wave and plume was smaller.

Are estimates of wind characteristics based on measurements with Pitot tubes and GNSS receivers mounted on consumer-grade unmanned aerial vehicles applicable in meteorological studies?

Science.gov (United States)

Niedzielski, Tomasz; Skjøth, Carsten; Werner, Małgorzata; Spallek, Waldemar; Witek, Matylda; Sawiński, Tymoteusz; Drzeniecka-Osiadacz, Anetta; Korzystka-Muskała, Magdalena; Muskała, Piotr; Modzel, Piotr; Guzikowski, Jakub; Kryza, Maciej

2017-09-01

The objective of this paper is to empirically show that estimates of wind speed and wind direction based on measurements carried out using the Pitot tubes and GNSS receivers, mounted on consumer-grade unmanned aerial vehicles (UAVs), may accurately approximate true wind parameters. The motivation for the study is that a growing number of commercial and scientific UAV operations may soon become a new source of data on wind speed and wind direction, with unprecedented spatial and temporal resolution. The feasibility study was carried out within an isolated mountain meadow of Polana Izerska located in the Izera Mountains (SW Poland) during an experiment which aimed to compare wind characteristics measured by several instruments: three UAVs (swinglet CAM, eBee, Maja) equipped with the Pitot tubes and GNSS receivers, wind speed and direction meters mounted at 2.5 and 10 m (mast), conventional weather station and vertical sodar. The three UAVs performed seven missions along spiral-like trajectories, most reaching 130 m above take-off location. The estimates of wind speed and wind direction were found to agree between UAVs. The time series of wind speed measured at 10 m were extrapolated to flight altitudes recorded at a given time so that a comparison was made feasible. It was found that the wind speed estimates provided by the UAVs on a basis of the Pitot tube/GNSS data are in agreement with measurements carried out using dedicated meteorological instruments. The discrepancies were recorded in the first and last phases of UAV flights.

New method to calibrate a spinner anemometer

DEFF Research Database (Denmark)

Demurtas, Giorgio; Friis Pedersen, Troels

2014-01-01

The spinner anemometer is a wind sensor, based on three one dimensional sonic sensor probes, mounted on the wind turbine spinner, and an algorithm to convert the wind speeds measured by the three sonic sensors to horizontal wind speed, yaw misalignment and flow inclination angle. The conversion...... algorithm utilizes two constants k1 and k2 that are specific to the spinner and blade root design and to the mounting position of the sonic sensors on the spinner. The two constants are calibrated by means of two different test and instrument set-ups. Both calibrations consider the rotor of the wind turbine...... to be stopped during calibration in order for the rotor induction not to influence on the calibration, so that the spinner anemometer measures ”free” wind values in stopped condition. The calibration of flow angle measurements is made by calibration of the ratio of the two algorithm constants k2=k1 = k...

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

Increasing the Performance of a Sliding Discharge Actuator Through the Application of Multiple Potentials

Science.gov (United States)

2011-09-01

particle image velocimetry (PIV). In probe measurement techniques a probe, either a pitot static probe or a CTA hot wire probe, is inserted into the flow...and pitot probes and noted the differences that resulted between the probe results and the PIV results by seeding material type [20]. The PIV setup...Barrier Discharge Aerodynamic Actuator,” AIAA Paper 2009–4285, 2009. 188 41. Humble, R., Henry , G., and Larson, W., Space Propulsion Analysis and Design

Line-feature-based calibration method of structured light plane parameters for robot hand-eye system

Science.gov (United States)

Qi, Yuhan; Jing, Fengshui; Tan, Min

2013-03-01

For monocular-structured light vision measurement, it is essential to calibrate the structured light plane parameters in addition to the camera intrinsic parameters. A line-feature-based calibration method of structured light plane parameters for a robot hand-eye system is proposed. Structured light stripes are selected as calibrating primitive elements, and the robot moves from one calibrating position to another with constraint in order that two misaligned stripe lines are generated. The images of stripe lines could then be captured by the camera fixed at the robot's end link. During calibration, the equations of two stripe lines in the camera coordinate system are calculated, and then the structured light plane could be determined. As the robot's motion may affect the effectiveness of calibration, so the robot's motion constraints are analyzed. A calibration experiment and two vision measurement experiments are implemented, and the results reveal that the calibration accuracy can meet the precision requirement of robot thick plate welding. Finally, analysis and discussion are provided to illustrate that the method has a high efficiency fit for industrial in-situ calibration.

New aspects in the implementation of the quasi-static method for the solution of neutron diffusion problems in the framework of a nodal method

International Nuclear Information System (INIS)

Caron, D.; Dulla, S.; Ravetto, P.

2016-01-01

Highlights: • The implementation of the quasi-static method in 3D nodal diffusion theory model in hexagonal-z geometry is described. • Different formulations of the quasi-static technique are discussed. • The results presented illustrate the features of the various formulations, highlighting advantages and drawbacks. • A novel adaptive procedure for the selection of the time interval between shape recalculations is presented. - Abstract: The ability to accurately model the dynamic behaviour of the neutron distribution in a nuclear system is a fundamental aspect of reactor design and safety assessment. Due to the heavy computational burden associated to the direct time inversion of the full model, the quasi-static method has become a standard approach to the numerical solution of the nuclear reactor dynamic equations on the full phase space. The present paper is opened by an introductory critical review of the basics of the quasi-static scheme for the general neutron kinetic problem. Afterwards, the implementation of the quasi-static method in the context of a three-dimensional nodal diffusion theory model in hexagonal-z geometry is described, including some peculiar aspects of the adjoint nodal equations and the explicit formulation of the quasi-static nodal equations. The presentation includes the discussion of different formulations of the quasi-static technique. The results presented illustrate the features of the various formulations, highlighting the corresponding advantages and drawbacks. An adaptive procedure for the selection of the time interval between shape recalculations is also presented, showing its usefulness in practical applications.

A method for the energy calibration of a heavy ion accelerator

International Nuclear Information System (INIS)

Martin, B.; Michaelsen, R.; Sethi, R.C.; Ziegler, K.

1985-01-01

A method for the absolute energy calibration of a heavy ion accelerator was developed at VICKSI. The method is based on the use of a suitably selected heavy ion beam to calibrate an analysing magnet. In front of the entrance slit of the analysing system the beam is stripped with a thin carbon foil. The charge states of the resulting ions cover the whole range from the charge state of the injected ions to the charge state of the fully stripped ions. Ion and energy of the beam have been selected in such a way that the rigidities corresponding to the different charge states cover the full rigidity range of the analysing magnet. The field of the analysing magnet is varied and the NMR-frequency corresponding to each transmitted charge state is obtained. For the absolute calibration a standard α-source is used. The functional dependence of the rigidity versus NMR-frequency can be used to compute the energy of any beam. At present this method gives an absolute accuracy of +-0.15%. The various sources of erros are described. (orig.)

Determination of calibration equations by means of the generalized least squares method

International Nuclear Information System (INIS)

Zijp, W.L.

1984-12-01

For the determination of two-dimensional calibration curves (e.g. in tank calibration procedures) or of three dimensional calibration equations (e.g. for the calibration of NDA equipment for enrichment measurements) one performs measurements under well chosen conditions, where all observables of interest (inclusive the values of the standard material) are subject to measurement uncertainties. Moreover correlations in several measurements may occur. This document describes the mathematical-statistical approach to determine the values of the model parameters and their covariance matrix, which fit best to the mathematical model for the calibration equation. The formulae are based on the method of generalized least squares where the term generalized implies that non-linear equations in the unknown parameters and also covariance matrices of the measurement data of the calibration can be taken into account. In the general case an iteration procedure is required. No iteration is required when the model is linear in the parameters and the covariance matrices for the measurements of co-ordinates of the calibration points are proportional to each other

Static Eccentricity Fault Recognition in Three-Phase Line Start Permanent Magnet Synchronous Motor Using Finite Element Method

Directory of Open Access Journals (Sweden)

Mahdi Karami

2014-01-01

Full Text Available This paper is dedicated to investigating static eccentricity in a three-phase LSPMSM. The modeling of LSPMSM with static eccentricity between stator and rotor is developed using finite element method (FEM. The analytical expression for the permeance and flux components of nonuniform air-gap due to static eccentricity fault is discussed. Various indexes for static eccentricity detection using stator current signal of IM and permanent magnet synchronous motor (PMSM are presented. Since LSPMSM is composed of a rotor which is a combination of these two motors, the ability of these features is evaluated for static eccentricity diagnosis in LSPMSM. The simulated stator current signal of LSPMSM in the presence of static eccentricity is analyzed in frequency domain using power spectral density (PSD. It is demonstrated that static eccentricity fault generates a series of low frequency harmonic components in the form of sidebands around the fundamental frequency. Moreover, the amplitudes of these components increase in proportion to the fault severity. According to the mentioned observations, an accurate frequency pattern is specified for static eccentricity detection in three-phase LSPMSM.

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.

Quantitative assessment of contact and non-contact lateral force calibration methods for atomic force microscopy

Energy Technology Data Exchange (ETDEWEB)

Tran Khac, Bien Cuong; Chung, Koo-Hyun, E-mail: khchung@ulsan.ac.kr

2016-02-15

Atomic Force Microscopy (AFM) has been widely used for measuring friction force at the nano-scale. However, one of the key challenges faced by AFM researchers is to calibrate an AFM system to interpret a lateral force signal as a quantifiable force. In this study, five rectangular cantilevers were used to quantitatively compare three different lateral force calibration methods to demonstrate the legitimacy and to establish confidence in the quantitative integrity of the proposed methods. The Flat-Wedge method is based on a variation of the lateral output on a surface with flat and changing slopes, the Multi-Load Pivot method is based on taking pivot measurements at several locations along the cantilever length, and the Lateral AFM Thermal-Sader method is based on determining the optical lever sensitivity from the thermal noise spectrum of the first torsional mode with a known torsional spring constant from the Sader method. The results of the calibration using the Flat-Wedge and Multi-Load Pivot methods were found to be consistent within experimental uncertainties, and the experimental uncertainties of the two methods were found to be less than 15%. However, the lateral force sensitivity determined by the Lateral AFM Thermal-Sader method was found to be 8–29% smaller than those obtained from the other two methods. This discrepancy decreased to 3–19% when the torsional mode correction factor for an ideal cantilever was used, which suggests that the torsional mode correction should be taken into account to establish confidence in Lateral AFM Thermal-Sader method. - Highlights: • Quantitative assessment of three lateral force calibration methods for AFM. • Advantages and disadvantages of three different lateral force calibration method. • Implementation of Multi-Load Pivot method as non-contact calibration technique. • The torsional mode correction for Lateral AFM Thermal-Sader method.

Quantitative assessment of contact and non-contact lateral force calibration methods for atomic force microscopy

International Nuclear Information System (INIS)

Tran Khac, Bien Cuong; Chung, Koo-Hyun

2016-01-01

Atomic Force Microscopy (AFM) has been widely used for measuring friction force at the nano-scale. However, one of the key challenges faced by AFM researchers is to calibrate an AFM system to interpret a lateral force signal as a quantifiable force. In this study, five rectangular cantilevers were used to quantitatively compare three different lateral force calibration methods to demonstrate the legitimacy and to establish confidence in the quantitative integrity of the proposed methods. The Flat-Wedge method is based on a variation of the lateral output on a surface with flat and changing slopes, the Multi-Load Pivot method is based on taking pivot measurements at several locations along the cantilever length, and the Lateral AFM Thermal-Sader method is based on determining the optical lever sensitivity from the thermal noise spectrum of the first torsional mode with a known torsional spring constant from the Sader method. The results of the calibration using the Flat-Wedge and Multi-Load Pivot methods were found to be consistent within experimental uncertainties, and the experimental uncertainties of the two methods were found to be less than 15%. However, the lateral force sensitivity determined by the Lateral AFM Thermal-Sader method was found to be 8–29% smaller than those obtained from the other two methods. This discrepancy decreased to 3–19% when the torsional mode correction factor for an ideal cantilever was used, which suggests that the torsional mode correction should be taken into account to establish confidence in Lateral AFM Thermal-Sader method. - Highlights: • Quantitative assessment of three lateral force calibration methods for AFM. • Advantages and disadvantages of three different lateral force calibration method. • Implementation of Multi-Load Pivot method as non-contact calibration technique. • The torsional mode correction for Lateral AFM Thermal-Sader method.

Corrected direct force balance method for atomic force microscopy lateral force calibration

International Nuclear Information System (INIS)

Asay, David B.; Hsiao, Erik; Kim, Seong H.

2009-01-01

This paper reports corrections and improvements of the previously reported direct force balance method (DFBM) developed for lateral calibration of atomic force microscopy. The DFBM method employs the lateral force signal obtained during a force-distance measurement on a sloped surface and relates this signal to the applied load and the slope of the surface to determine the lateral calibration factor. In the original publication [Rev. Sci. Instrum. 77, 043903 (2006)], the tip-substrate contact was assumed to be pinned at the point of contact, i.e., no slip along the slope. In control experiments, the tip was found to slide along the slope during force-distance curve measurement. This paper presents the correct force balance for lateral force calibration.

Analysis of Applicability of Flow Averaging Pitot Tubes in the Areas of Flow Disturbance

Directory of Open Access Journals (Sweden)

Pochwała Sławomir

2016-03-01

Full Text Available The issues connected with the complex design of various facilities, including up-to-date boiler equipment as well as the ways of organizing the space around them, are the reasons why there is often a lack of room for mounting a flowmeter in accordance with the recommendations of manufacturers. In most cases the problem is associated with ensuring sufficient lengths of straight pipe leading into and out of a flowmeter. When this condition cannot be fulfilled, the uncertainty of measurement increases above the value guaranteed by the manufacturer of the flowmeter. This sort of operation problem has encouraged the authors of this paper to undertake research aimed at the analysis of applicability of averaging Pitot tubes in the areas of flow disturbance.

On Inertial Body Tracking in the Presence of Model Calibration Errors.

Science.gov (United States)

Miezal, Markus; Taetz, Bertram; Bleser, Gabriele

2016-07-22

In inertial body tracking, the human body is commonly represented as a biomechanical model consisting of rigid segments with known lengths and connecting joints. The model state is then estimated via sensor fusion methods based on data from attached inertial measurement units (IMUs). This requires the relative poses of the IMUs w.r.t. the segments-the IMU-to-segment calibrations, subsequently called I2S calibrations-to be known. Since calibration methods based on static poses, movements and manual measurements are still the most widely used, potentially large human-induced calibration errors have to be expected. This work compares three newly developed/adapted extended Kalman filter (EKF) and optimization-based sensor fusion methods with an existing EKF-based method w.r.t. their segment orientation estimation accuracy in the presence of model calibration errors with and without using magnetometer information. While the existing EKF-based method uses a segment-centered kinematic chain biomechanical model and a constant angular acceleration motion model, the newly developed/adapted methods are all based on a free segments model, where each segment is represented with six degrees of freedom in the global frame. Moreover, these methods differ in the assumed motion model (constant angular acceleration, constant angular velocity, inertial data as control input), the state representation (segment-centered, IMU-centered) and the estimation method (EKF, sliding window optimization). In addition to the free segments representation, the optimization-based method also represents each IMU with six degrees of freedom in the global frame. In the evaluation on simulated and real data from a three segment model (an arm), the optimization-based method showed the smallest mean errors, standard deviations and maximum errors throughout all tests. It also showed the lowest dependency on magnetometer information and motion agility. Moreover, it was insensitive w.r.t. I2S position and

Improving agreement between static method and dynamic formula for driven cast-in-place piles.

Science.gov (United States)

2013-06-01

This study focuses on comparing the capacities and lengths of piling necessary as determined with a static method and with a dynamic formula. Pile capacities and their required lengths are determined two ways: 1) using a design and computed method, s...

Velocity-pressure correlation measurements in complex free shear flows

International Nuclear Information System (INIS)

Naka, Yoshitsugu; Obi, Shinnosuke

2009-01-01

Simultaneous measurements of fluctuating velocity and pressure were performed in various turbulent free shear flows including a turbulent mixing layer and the wing-tip vortex trailing from a NACA0012 half-wing. Two different methods for fluctuating static pressure measurement were considered: a direct method using a miniature Pitot tube and an indirect method where static pressure was calculated from total pressure. The pressure obtained by either of these methods was correlated with the velocity measured by an X-type hot-wire probe. The results from these two techniques agreed with each other in the turbulent mixing layer. In the wing-tip vortex case, however, some discrepancies were found, although overall characteristics of the pressure-related statistics were adequately captured by both methods.

76 FR 33658 - Airworthiness Directives; Bombardier, Inc. Model CL-600-2B19 (Regional Jet Series 100 & 440...

Science.gov (United States)

2011-06-09

... substance. But we might have found it necessary to use different words from those in the MCAI to ensure the... after heavy rain, the pitot-static tubing may become partially or completely blocked by water, which...-static system include check valves, which impede the entry of water into the drain bottle. This condition...

EPMT: a portable transfer standard for telemetry system pressure-transducer calibration

International Nuclear Information System (INIS)

Hasbrouck, R.T.

1977-01-01

The LLL developed electronic pressure meter (EPMT) is a portable static-pressure calibration instrument for use with the LLL telemetry transducer system at the Nevada Test Site (NTS). It is significantly more accurate and rugged than the bourdon-tube pressure gauge it replaces, and can be incorporated into a field-use, semi-automatic, pressure calibration system. The process by which a transducer is selected for EPMT use from the inventory of field-service-certified transducers and subjected to an extensive preconditioning and calibration procedure is described. By combining this unusual calibration procedure with a unique, statistically based data-reduction routine, the total uncertainty of the measuring process at each calibration point can be determined with high accuracy

Comparison of two methods of therapy level calibration at 60Co gamma beams

International Nuclear Information System (INIS)

Bjerke, H.; Jaervinen, H.; Grimbergen, T.W.M.; Grindborg, J.E.; Chauvenet, B.; Czap, L.; Ennow, K.; Moretti, C.; Rocha, P.

1998-01-01

The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60 Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60 Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60 Co gamma beams in terms of absorbed dose to water is taken into routine use. (author)

Comparison of two methods of therapy level calibration at 60Co gamma beams

International Nuclear Information System (INIS)

Bjerke, H; Jaervinen, H; Grimbergen, T W M; Grindborg, J-E; Chauvenet, B; Czap, L; Ennow, K; Moretti, C; Rocha, P

1998-01-01

The accuracy and traceability of the calibration of radiotherapy dosimeters is of great concern to those involved in the delivery of radiotherapy. It has been proposed that calibration should be carried out directly in terms of absorbed dose to water, instead of using the conventional and widely applied quantity of air kerma. In this study, the faithfulness in disseminating standards of both air kerma and absorbed dose to water were evaluated, through comparison of both types of calibration for three types of commonly used radiotherapy dosimeters at 60 Co gamma beams at a few secondary and primary standard dosimetry laboratories (SSDLs and PSDLs). A supplementary aim was to demonstrate the impact which the change in the method of calibration would have on clinical dose measurements at the reference point. Within the estimated uncertainties, both the air kerma and absorbed dose to water calibration factors obtained at different laboratories were regarded as consistent. As might be expected, between the SSDLs traceable to the same PSDL the observed differences were smaller (less than 0.5%) than between PSDLs or SSDLs traceable to different PSDLs (up to 1.5%). This can mainly be attributed to the reported differences between the primary standards. The calibration factors obtained by the two methods differed by up to about 1.5% depending on the primary standards involved and on the parameters of calculation used for 60 Co gamma radiation. It is concluded that this discrepancy should be settled before the new method of calibration at 60 Co gamma beams in terms of absorbed dose to water is taken into routine use

Calibration of quantitative neutron radiography method for moisture measurement

International Nuclear Information System (INIS)

Nemec, T.; Jeraj, R.

1999-01-01

Quantitative measurements of moisture and hydrogenous matter in building materials by neutron radiography (NR) are regularly performed at TRIGA Mark II research of 'Jozef Stefan' Institute in Ljubljana. Calibration of quantitative method is performed using standard brick samples with known moisture content and also with a secondary standard, plexiglas step wedge. In general, the contribution of scattered neutrons to the neutron image is not determined explicitly what introduces an error to the measured signal. Influence of scattered neutrons is significant in regions with high gradients of moisture concentrations, where the build up of scattered neutrons causes distortion of the moisture concentration profile. In this paper detailed analysis of validity of our calibration method for different geometrical parameters is presented. The error in the measured hydrogen concentration is evaluated by an experiment and compared with results obtained by Monte Carlo calculation with computer code MCNP 4B. Optimal conditions are determined for quantitative moisture measurements in order to minimize the error due to scattered neutrons. The method is tested on concrete samples with high moisture content.(author)

NEW METHOD FOR THE CALIBRATION OF MULTI-CAMERA MOBILE MAPPING SYSTEMS

Directory of Open Access Journals (Sweden)

A. P. Kersting

2012-07-01

Full Text Available Mobile Mapping Systems (MMS allow for fast and cost-effective collection of geo-spatial information. Such systems integrate a set of imaging sensors and a position and orientation system (POS, which entails GPS and INS units. System calibration is a crucial process to ensure the attainment of the expected accuracy of such systems. It involves the calibration of the individual sensors as well as the calibration of the mounting parameters relating the system components. The mounting parameters of multi-camera MMS include two sets of relative orientation parameters (ROP: the lever arm offsets and the boresight angles relating the cameras and the IMU body frame and the ROP among the cameras (in the absence of GPS/INS data. In this paper, a novel single-step calibration method, which has the ability of estimating these two sets of ROP, is devised. Besides the ability to estimate the ROP among the cameras, the proposed method can use such parameters as prior information in the ISO procedure. The implemented procedure consists of an integrated sensor orientation (ISO where the GPS/INS-derived position and orientation and the system mounting parameters are directly incorporated in the collinearity equations. The concept of modified collinearity equations has been used by few authors for single-camera systems. In this paper, a new modification to the collinearity equations for GPS/INS-assisted multicamera systems is introduced. Experimental results using a real dataset demonstrate the feasibility of the proposed method.

New Method for the Calibration of Multi-Camera Mobile Mapping Systems

Science.gov (United States)

Kersting, A. P.; Habib, A.; Rau, J.

2012-07-01

Mobile Mapping Systems (MMS) allow for fast and cost-effective collection of geo-spatial information. Such systems integrate a set of imaging sensors and a position and orientation system (POS), which entails GPS and INS units. System calibration is a crucial process to ensure the attainment of the expected accuracy of such systems. It involves the calibration of the individual sensors as well as the calibration of the mounting parameters relating the system components. The mounting parameters of multi-camera MMS include two sets of relative orientation parameters (ROP): the lever arm offsets and the boresight angles relating the cameras and the IMU body frame and the ROP among the cameras (in the absence of GPS/INS data). In this paper, a novel single-step calibration method, which has the ability of estimating these two sets of ROP, is devised. Besides the ability to estimate the ROP among the cameras, the proposed method can use such parameters as prior information in the ISO procedure. The implemented procedure consists of an integrated sensor orientation (ISO) where the GPS/INS-derived position and orientation and the system mounting parameters are directly incorporated in the collinearity equations. The concept of modified collinearity equations has been used by few authors for single-camera systems. In this paper, a new modification to the collinearity equations for GPS/INS-assisted multicamera systems is introduced. Experimental results using a real dataset demonstrate the feasibility of the proposed method.

Balanced calibration of resonant piezoelectric RL shunts with quasi-static background flexibility correction

DEFF Research Database (Denmark)

Høgsberg, Jan Becker; Krenk, Steen

2015-01-01

Resonant RL shunt circuits constitute a robust approach to piezoelectric damping, where the performance with respect to damping of flexible structures requires a precise calibration of the corresponding circuit components. The balanced calibration procedure of the present paper is based on equal ...... that the procedure leads to equal modal damping and effective response reduction, even for rather indirect placement of the transducer, provided that the correction for background flexibility is included in the calibration procedure....

A global calibration method for multiple vision sensors based on multiple targets

International Nuclear Information System (INIS)

Liu, Zhen; Zhang, Guangjun; Wei, Zhenzhong; Sun, Junhua

2011-01-01

The global calibration of multiple vision sensors (MVS) has been widely studied in the last two decades. In this paper, we present a global calibration method for MVS with non-overlapping fields of view (FOVs) using multiple targets (MT). MT is constructed by fixing several targets, called sub-targets, together. The mutual coordinate transformations between sub-targets need not be known. The main procedures of the proposed method are as follows: one vision sensor is selected from MVS to establish the global coordinate frame (GCF). MT is placed in front of the vision sensors for several (at least four) times. Using the constraint that the relative positions of all sub-targets are invariant, the transformation matrix from the coordinate frame of each vision sensor to GCF can be solved. Both synthetic and real experiments are carried out and good result is obtained. The proposed method has been applied to several real measurement systems and shown to be both flexible and accurate. It can serve as an attractive alternative to existing global calibration methods

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...

Measurement of mass flux in two-phase flow using combinations of Pitot tubes and gamma densitometers

International Nuclear Information System (INIS)

Hau, K.F.F.L.; Banerjee, S.

1981-01-01

New experimental data indicate that mass flux in cocurrent gas-liquid flows may be determined by the use of Pitot tubes in conjunction with a local mixture density measurement technique. The data were taken over a wide range of flow regimes in a horizontal pipe and included separated patterns such as stratified and annular flows. Local mixture densities were obtained by a computer-assisted algebraic reconstruction technique that used chordal average densities measured by traversing gamma beam attenuation. The results extend the applicability of this mass flux measurement technique well beyond the relatively homogeneous, high-pressure, steam-water flow situations originally studied by S. Banerjee and D.M. Nguyen. 13 refs

[Research on Spectral Polarization Imaging System Based on Static Modulation].

Science.gov (United States)

Zhao, Hai-bo; Li, Huan; Lin, Xu-ling; Wang, Zheng

2015-04-01

The main disadvantages of traditional spectral polarization imaging system are: complex structure, with moving parts, low throughput. A novel method of spectral polarization imaging system is discussed, which is based on static polarization intensity modulation combined with Savart polariscope interference imaging. The imaging system can obtain real-time information of spectral and four Stokes polarization messages. Compared with the conventional methods, the advantages of the imaging system are compactness, low mass and no moving parts, no electrical control, no slit and big throughput. The system structure and the basic theory are introduced. The experimental system is established in the laboratory. The experimental system consists of reimaging optics, polarization intensity module, interference imaging module, and CCD data collecting and processing module. The spectral range is visible and near-infrared (480-950 nm). The white board and the plane toy are imaged by using the experimental system. The ability of obtaining spectral polarization imaging information is verified. The calibration system of static polarization modulation is set up. The statistical error of polarization degree detection is less than 5%. The validity and feasibility of the basic principle is proved by the experimental result. The spectral polarization data captured by the system can be applied to object identification, object classification and remote sensing detection.

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.

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

Science.gov (United States)

Sun, Ting; Xing, Fei; You, Zheng

2013-04-08

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.

Calibration method based on direct radioactivity measurement for radioactive gas monitoring instruments

International Nuclear Information System (INIS)

Yoshida, Makoto; Ohi, Yoshihiro; Chida, Tohru; Wu, Youyang.

1993-01-01

A calibration method for radioactive gas monitoring instruments was studied. In the method, gaseous radioactivity standards were provided on the basis of the direct radioactivity measurement by the diffusion-in long proportional counter method (DLPC method). The radioactivity concentration of the gas mixture through a monitoring instrument was determined by sampling the known volume of the gas mixture into the proportional counter used for the DLPC method. Since oxygen in the gas mixture decreased the counting efficiency in a proportional counter, the influence on calibration was experimentally estimated. It was not serious and able to be easily corrected. By the present method, the relation between radioactivity concentration and ionization current was determined for a gas-flow ionization chamber with 1.5 l effective volume. It showed good agreement with the results in other works. (author)

A three-step calibration method for tri-axial field sensors in a 3D magnetic digital compass

International Nuclear Information System (INIS)

Zhu, Xiaoning; Zhao, Ta; Zhou, Zhijian; Cheng, Defu

2017-01-01

In a 3D magnetic compass, it is important to calibrate the tri-axial magnetometers and accelerometers so the compass will provide accurate heading and attitude information. Previous researchers have used two methods to calibrate these two field sensors separately, i.e. the classic independent ellipsoid fitting method and the independent dot product invariant method, respectively. Both methods are easy to use, and no highly accurate, external equipment is required. However, self-calibration with ellipsoid fitting has the disadvantage that it interfuses an orthogonal matrix, and the dot product invariant method requires the use of pre-calibrated internal field sensors, which may be unavailable in many cases. In this paper, we have introduced and unified an error model of two tri-axial field sensors. Accordingly, the orthogonal matrix caused by ellipsoid fitting was mathematically proved to be the combination of two sources, the mounting misalignment and the rotation misalignment. Moreover, a new method, which we call optimal resultant vector, was proposed to further calibrate multi-sensor systems on the basis of ellipsoid fitting and dot product invariant methods, establishing a new, three-step calibration method. The superiority of the proposed method over the state-of-the-art approaches were demonstrated by simulations and a 3D compass experiment. (paper)

Simultaneous calibration phantom commission and geometry calibration in cone beam CT

Science.gov (United States)

Xu, Yuan; Yang, Shuai; Ma, Jianhui; Li, Bin; Wu, Shuyu; Qi, Hongliang; Zhou, Linghong

2017-09-01

Geometry calibration is a vital step for describing the geometry of a cone beam computed tomography (CBCT) system and is a prerequisite for CBCT reconstruction. In current methods, calibration phantom commission and geometry calibration are divided into two independent tasks. Small errors in ball-bearing (BB) positioning in the phantom-making step will severely degrade the quality of phantom calibration. To solve this problem, we propose an integrated method to simultaneously realize geometry phantom commission and geometry calibration. Instead of assuming the accuracy of the geometry phantom, the integrated method considers BB centers in the phantom as an optimized parameter in the workflow. Specifically, an evaluation phantom and the corresponding evaluation contrast index are used to evaluate geometry artifacts for optimizing the BB coordinates in the geometry phantom. After utilizing particle swarm optimization, the CBCT geometry and BB coordinates in the geometry phantom are calibrated accurately and are then directly used for the next geometry calibration task in other CBCT systems. To evaluate the proposed method, both qualitative and quantitative studies were performed on simulated and realistic CBCT data. The spatial resolution of reconstructed images using dental CBCT can reach up to 15 line pair cm-1. The proposed method is also superior to the Wiesent method in experiments. This paper shows that the proposed method is attractive for simultaneous and accurate geometry phantom commission and geometry calibration.

A new method for automated dynamic calibration of tipping-bucket rain gauges

Science.gov (United States)

Humphrey, M.D.; Istok, J.D.; Lee, J.Y.; Hevesi, J.A.; Flint, A.L.

1997-01-01

Existing methods for dynamic calibration of tipping-bucket rain gauges (TBRs) can be time consuming and labor intensive. A new automated dynamic calibration system has been developed to calibrate TBRs with minimal effort. The system consists of a programmable pump, datalogger, digital balance, and computer. Calibration is performed in two steps: 1) pump calibration and 2) rain gauge calibration. Pump calibration ensures precise control of water flow rates delivered to the rain gauge funnel; rain gauge calibration ensures precise conversion of bucket tip times to actual rainfall rates. Calibration of the pump and one rain gauge for 10 selected pump rates typically requires about 8 h. Data files generated during rain gauge calibration are used to compute rainfall intensities and amounts from a record of bucket tip times collected in the field. The system was tested using 5 types of commercial TBRs (15.2-, 20.3-, and 30.5-cm diameters; 0.1-, 0.2-, and 1.0-mm resolutions) and using 14 TBRs of a single type (20.3-cm diameter; 0.1-mm resolution). Ten pump rates ranging from 3 to 154 mL min-1 were used to calibrate the TBRs and represented rainfall rates between 6 and 254 mm h-1 depending on the rain gauge diameter. All pump calibration results were very linear with R2 values greater than 0.99. All rain gauges exhibited large nonlinear underestimation errors (between 5% and 29%) that decreased with increasing rain gauge resolution and increased with increasing rainfall rate, especially for rates greater than 50 mm h-1. Calibration curves of bucket tip time against the reciprocal of the true pump rate for all rain gauges also were linear with R2 values of 0.99. Calibration data for the 14 rain gauges of the same type were very similar, as indicated by slope values that were within 14% of each other and ranged from about 367 to 417 s mm h-1. The developed system can calibrate TBRs efficiently, accurately, and virtually unattended and could be modified for use with other

A Multi-Projector Calibration Method for Virtual Reality Simulators with Analytically Defined Screens

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Cristina Portalés

2017-06-01

Full Text Available The geometric calibration of projectors is a demanding task, particularly for the industry of virtual reality simulators. Different methods have been developed during the last decades to retrieve the intrinsic and extrinsic parameters of projectors, most of them being based on planar homographies and some requiring an extended calibration process. The aim of our research work is to design a fast and user-friendly method to provide multi-projector calibration on analytically defined screens, where a sample is shown for a virtual reality Formula 1 simulator that has a cylindrical screen. The proposed method results from the combination of surveying, photogrammetry and image processing approaches, and has been designed by considering the spatial restrictions of virtual reality simulators. The method has been validated from a mathematical point of view, and the complete system—which is currently installed in a shopping mall in Spain—has been tested by different users.

Calibrating a combined energy systems analysis and controller design method with empirical data

International Nuclear Information System (INIS)

Murphy, Gavin Bruce; Counsell, John; Allison, John; Brindley, Joseph

2013-01-01

The drive towards low carbon constructions has seen buildings increasingly utilise many different energy systems simultaneously to control the human comfort of the indoor environment; such as ventilation with heat recovery, various heating solutions and applications of renewable energy. This paper describes a dynamic modelling and simulation method (IDEAS – Inverse Dynamics based Energy Assessment and Simulation) for analysing the energy utilisation of a building and its complex servicing systems. The IDEAS case study presented in this paper is based upon small perturbation theory and can be used for the analysis of the performance of complex energy systems and also for the design of smart control systems. This paper presents a process of how any dynamic model can be calibrated against a more empirical based data model, in this case the UK Government's SAP (Standard Assessment Procedure). The research targets of this work are building simulation experts for analysing the energy use of a building and also control engineers to assist in the design of smart control systems for dwellings. The calibration process presented is transferable and has applications for simulation experts to assist in calibrating any dynamic building simulation method with an empirical based method. - Highlights: • Presentation of an energy systems analysis method for assessing the energy utilisation of buildings and their complex servicing systems. • An inverse dynamics based controller design method is detailed. • Method of how a dynamic model can be calibrated with an empirical based model

Validation of a densimeter calibration procedure for a secondary calibration laboratory

International Nuclear Information System (INIS)

Alpizar Herrera, Juan Carlos

2014-01-01

A survey was conducted to quantify the need for calibration of a density measurement instrument at the research units at the Sede Rodrigo Facio of the Universidad de Costa Rica. A calibration procedure was documented for the instrument that presented the highest demand in the survey by the calibration service. A study of INTE-ISO/IEC 17025: 2005 and specifically in section 5.4 of this standard was done, to document the procedure for calibrating densimeters. Densimeter calibration procedures and standards were sought from different national and international sources. The method of hydrostatic weighing or Cuckow method was the basis of the defined procedure. Documenting the calibration procedure and creating other documents was performed for data acquisition log, intermediate calculation log and calibration certificate copy. A veracity test was performed using as reference laboratory a laboratory of calibration secondary national as part of the validation process of the documented procedure. The results of the E_n statistic of 0.41; 0.34 and 0.46 for the calibration points 90%, 50% and 10% were obtained for the densimeter scale respectively. A reproducibility analysis of the method was performed with satisfactory results. Different suppliers were contacted to estimate the economic costs of the equipment and materials, needed to develop the documented method of densimeter calibration. The acquisition of an analytical balance was recommended, instead of a precision scale, in order to improve the results obtained with the documented method [es

Comparing Single-Point and Multi-point Calibration Methods in Modulated DSC

Energy Technology Data Exchange (ETDEWEB)

Van Buskirk, Caleb Griffith [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-06-14

Heat capacity measurements for High Density Polyethylene (HDPE) and Ultra-high Molecular Weight Polyethylene (UHMWPE) were performed using Modulated Differential Scanning Calorimetry (mDSC) over a wide temperature range, -70 to 115 °C, with a TA Instruments Q2000 mDSC. The default calibration method for this instrument involves measuring the heat capacity of a sapphire standard at a single temperature near the middle of the temperature range of interest. However, this method often fails for temperature ranges that exceed a 50 °C interval, likely because of drift or non-linearity in the instrument's heat capacity readings over time or over the temperature range. Therefore, in this study a method was developed to calibrate the instrument using multiple temperatures and the same sapphire standard.

Comparison of methods of calibration of a neutron probe by gravimetry or neutron-capture model

International Nuclear Information System (INIS)

Vachaud, G.; Royer, J.M.; Cooper, J.D.

1977-01-01

This paper presents a systematic analysis of two methods used for determining calibration curves of neutron probes. The uncertainties resulting from the use of the gravimetric method, with a linear correlation between count rates and water content of soil samples, are considered first. Particular care is given to the determination of errors in the values of water content and count rates, and to the difficulties arising from the choice of the correlation technique. The neutron-calibration curve of the soil was also obtained with a technique based on the determination of neutron thermal adsorption and diffusion constants. The importance of errors associated with this method is also analyzed. Different field examples are then presented. It appears that the neutron-capture technique should be particularly well suited for determining the calibration curve of clay soils or heterogeneous materials for which the gravimetric calibration technique cannot be applied with confidence. On the other hand, it is also shown that for a soil with a very well-defined gravimetric calibration curve, the neutron-capture technique gives results still at least as good as with the former method

Calibration method of microgrid polarimeters with image interpolation.

Science.gov (United States)

Chen, Zhenyue; Wang, Xia; Liang, Rongguang

2015-02-10

Microgrid polarimeters have large advantages over conventional polarimeters because of the snapshot nature and because they have no moving parts. However, they also suffer from several error sources, such as fixed pattern noise (FPN), photon response nonuniformity (PRNU), pixel cross talk, and instantaneous field-of-view (IFOV) error. A characterization method is proposed to improve the measurement accuracy in visible waveband. We first calibrate the camera with uniform illumination so that the response of the sensor is uniform over the entire field of view without IFOV error. Then a spline interpolation method is implemented to minimize IFOV error. Experimental results show the proposed method can effectively minimize the FPN and PRNU.

Real-time dynamic calibration of a tunable frequency laser source using a Fabry-Pérot interferometer

Energy Technology Data Exchange (ETDEWEB)

Mandula, Gábor, E-mail: mandula.gabor@wigner.mta.hu; Kis, Zsolt; Lengyel, Krisztián [Wigner Research Centre for Physics of the Hungarian Academy of Sciences, Konkoly-Thege Miklós út 29-33, H-1121 Budapest (Hungary)

2015-12-15

We report on a method for real-time dynamic calibration of a tunable external cavity diode laser by using a partially mode-matched plano-concave Fabry-Pérot interferometer in reflection geometry. Wide range laser frequency scanning is carried out by piezo-driven tilting of a diffractive grating playing the role of a frequency selective mirror in the laser cavity. The grating tilting system has a considerable mechanical inertness, so static laser frequency calibration leads to false results. The proposed real-time dynamic calibration based on the identification of primary- and Gouy-effect type secondary interference peaks with known frequency and temporal history can be used for a wide scanning range (from 0.2 GHz to more than 1 GHz). A concave spherical mirror with a radius of R = 100 cm and a plain 1% transmitting mirror was used as a Fabry-Pérot interferometer with various resonator lengths to investigate and demonstrate real-time calibration procedures for two kinds of laser frequency scanning functions.

Is the molecular statics method suitable for the study of nanomaterials? A study case of nanowires

International Nuclear Information System (INIS)

Chang, I-L; Chen, Y-C

2007-01-01

Both molecular statics and molecular dynamics methods were employed to study the mechanical properties of copper nanowires. The size effect on both elastic and plastic properties of square cross-sectional nanowire was examined and compared systematically using two molecular approaches. It was found consistently from both molecular methods that the elastic and plastic properties of nanowires depend on the lateral size of nanowires. As the lateral size of nanowires decreases, the values of Young's modulus decrease and dislocation nucleation stresses increase. However, it was shown that the dislocation nucleation stress would be significantly influenced by the axial periodic length of the nanowire model using the molecular statics method while molecular dynamics simulations at two distinct temperatures (0.01 and 300 K) did not show the same dependence. It was concluded that molecular statics as an energy minimization numerical scheme is quite insensitive to the instability of atomic structure especially without thermal fluctuation and might not be a suitable tool for studying the behaviour of nanomaterials beyond the elastic limit

Synthetic samples as imitators of elements composition for calibration in nuclear-physical methods of analysis

International Nuclear Information System (INIS)

Lakhov, V.M.; Gerling, V.Eh.; Il'ina, L.K.; Trojnina, G.G.; Galisheva, Eh.P.

1987-01-01

The papers on the problems of developing and application of synthetic standard samples (SS), imitating the substance and material (rocks, ores) element composition aimed at calibration, testing and certification of the equipment as well as check on the results of neutron-activation, X-ray spectral, X-ray radiometric, X-ray fluorescence and other nuclear-physical methods of analysis, are reviewed. It is shown that choice of SS preparation method is defined by peculiarities of analysis method for which calibration SS is designed. Experience in application of SS imitators of element composition in interlaboratory comparisons testifies to potential application of synthetic SS for calibration in different methods of analysis including, nuclear-physical ones

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

Acoustic and wind speed data analysis as an environmental issue

International Nuclear Information System (INIS)

Whitson, R.J.; MacKinnon, A.

1995-01-01

This paper examines how the output from a cup anemometer, used for wind speed measurement, can be recorded on magnetic tape and analysed using instrumentation normally employed to measure acoustic data. The purpose of this being to allow true simultaneous analysis of acoustic and wind speed data. NEL's NWTC (National Wind Turbine Centre) Anemometer Calibration Facility is used to compare pulsed and analogue outputs from a typical anemometer to the data obtained from a pitot/static tube for a range of different wind speeds. The usefulness of 1/24- and 1/12-octave analysis is examined and accuracy limits are derived for the 'acoustic' approach to wind speed measurement. The allowable positions for anemometer locations are also discussed with reference to currently available standards and recommended practices. (Author)

Calibration uncertainty

DEFF Research Database (Denmark)

Heydorn, Kaj; Anglov, Thomas

2002-01-01

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...

Static electricity: A literature review

Science.gov (United States)

Crow, Rita M.

1991-11-01

The major concern with static electricity is its discharging in a flammable atmosphere which can explode and cause a fire. Textile materials can have their electrical resistivity decreased by the addition of antistatic finishes, imbedding conductive particles into the fibres or by adding metal fibers to the yarns. The test methods used in the studies of static electricity include measuring the static properties of materials, of clothed persons, and of the ignition energy of flammable gases. Surveys have shown that there is sparse evidence for fires definitively being caused by static electricity. However, the 'worst-case' philosophy has been adopted and a static electricity safety code is described, including correct grounding procedures and the wearing of anti-static clothing and footwear.

New Systematic CFD Methods to Calculate Static and Single Dynamic Stability Derivatives of Aircraft

Directory of Open Access Journals (Sweden)

Bai-gang Mi

2017-01-01

Full Text Available Several new systematic methods for high fidelity and reliability calculation of static and single dynamic derivatives are proposed in this paper. Angle of attack step response is used to obtain static derivative directly; then translation acceleration dynamic derivative and rotary dynamic derivative can be calculated by employing the step response motion of rate of the angle of attack and unsteady motion of pitching angular velocity step response, respectively. Longitudinal stability derivative calculations of SACCON UCAV are taken as test cases for validation. Numerical results of all cases achieve good agreement with reference values or experiments data from wind tunnel, which indicate that the proposed methods can be considered as new tools in the process of design and production of advanced aircrafts for their high efficiency and precision.

Error Analysis and Calibration Method of a Multiple Field-of-View Navigation System.

Science.gov (United States)

Shi, Shuai; Zhao, Kaichun; You, Zheng; Ouyang, Chenguang; Cao, Yongkui; Wang, Zhenzhou

2017-03-22

The Multiple Field-of-view Navigation System (MFNS) is a spacecraft subsystem built to realize the autonomous navigation of the Spacecraft Inside Tiangong Space Station. This paper introduces the basics of the MFNS, including its architecture, mathematical model and analysis, and numerical simulation of system errors. According to the performance requirement of the MFNS, the calibration of both intrinsic and extrinsic parameters of the system is assumed to be essential and pivotal. Hence, a novel method based on the geometrical constraints in object space, called checkerboard-fixed post-processing calibration (CPC), is proposed to solve the problem of simultaneously obtaining the intrinsic parameters of the cameras integrated in the MFNS and the transformation between the MFNS coordinate and the cameras' coordinates. This method utilizes a two-axis turntable and a prior alignment of the coordinates is needed. Theoretical derivation and practical operation of the CPC method are introduced. The calibration experiment results of the MFNS indicate that the extrinsic parameter accuracy of the CPC reaches 0.1° for each Euler angle and 0.6 mm for each position vector component (1σ). A navigation experiment verifies the calibration result and the performance of the MFNS. The MFNS is found to work properly, and the accuracy of the position vector components and Euler angle reaches 1.82 mm and 0.17° (1σ) respectively. The basic mechanism of the MFNS may be utilized as a reference for the design and analysis of multiple-camera systems. Moreover, the calibration method proposed has practical value for its convenience for use and potential for integration into a toolkit.

Another look at volume self-calibration: calibration and self-calibration within a pinhole model of Scheimpflug cameras

International Nuclear Information System (INIS)

Cornic, Philippe; Le Besnerais, Guy; Champagnat, Frédéric; Illoul, Cédric; Cheminet, Adam; Le Sant, Yves; Leclaire, Benjamin

2016-01-01

We address calibration and self-calibration of tomographic PIV experiments within a pinhole model of cameras. A complete and explicit pinhole model of a camera equipped with a 2-tilt angles Scheimpflug adapter is presented. It is then used in a calibration procedure based on a freely moving calibration plate. While the resulting calibrations are accurate enough for Tomo-PIV, we confirm, through a simple experiment, that they are not stable in time, and illustrate how the pinhole framework can be used to provide a quantitative evaluation of geometrical drifts in the setup. We propose an original self-calibration method based on global optimization of the extrinsic parameters of the pinhole model. These methods are successfully applied to the tomographic PIV of an air jet experiment. An unexpected by-product of our work is to show that volume self-calibration induces a change in the world frame coordinates. Provided the calibration drift is small, as generally observed in PIV, the bias on the estimated velocity field is negligible but the absolute location cannot be accurately recovered using standard calibration data. (paper)

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.

Research on micromanipulator’s clamping force sensing based on static wirerope tension of a surgical robot

Directory of Open Access Journals (Sweden)

Lingtao Yu

2015-04-01

Full Text Available The micromanipulator’s force feedback is one of the key research contents of minimally invasive surgical robotic system. Because the micromanipulator is a kind of compact construction which is suitable for valve installation with small space in surgery, especially for the influence of disinfection method, there are major difficulties and limitations to integrate compact sensors in the end of micromanipulator. This article focuses on the 3-degree-of-freedom micromanipulator’s clamping force sensing, and these three joints are actuated by wirerope driving. A clamping force sensing method is proposed based on static tension of wirerope driving, and a static model between the clamping force and wirerope’s static tension is established considering the influence of real friction resistance in the mechanical system. Finally, an equivalent experimental test platform for 3-degree-of-freedom micromanipulator’s clamping force sensing is set up, and then a series of experiments of the clamping force are studied. The frictional resistances of wirerope between the guide plate and guide pulley mechanism are tested, and a calibration and correction method of the experimental clamping force is proposed. The final experiment results show that the total average accuracy of experimental clamping force is about 78.3%, and it can be the basic measurement force to realize micromanipulator’s clamping force feedback of a minimally invasive surgical robot.

Evaluation of a Pitot type spirometer in helium/oxygen mixtures.

Science.gov (United States)

Søndergaard, S; Kárason, S; Lundin, S; Stenqvist, O

1998-08-01

Mixtures of helium and oxygen are regaining a place in the treatment of obstruction of the upper and lower respiratory tract. The parenchymal changes during the course of IRDS or ARDS may also benefit from the reintroduction of helium/oxygen. In order to monitor and document the effect of low-density gas mixtures, we evaluated the Datex AS/3 Side Stream Spirometry module with D-lite (Datex-Engstrom Instrumentarium Corporation, Finland) against two golden standards. Under conditions simulating controlled and spontaneous ventilation with gas mixtures of He (approx. 80, 50, and 20%)/O2 or N2(approx. 21 and 79%)/02, simultaneous measurements using Biotek Ventilator Tester (Bio-Tek Instr., Vermont, USA) or body plethysmograph (SensorMedics System, Anaheim, USA) were correlated with data from the spirometry module. Data were analyzed according to a statistical regression model resulting in a best-fit equation based on density, voltage, and volume measurements. As expected, the D-lite (a modified Pitot tube) showed density-dependent behaviour. Regression equations and percentage deviation of estimated versus measured values were calculated. Measurements with the D-lite using low-density gases are satisfactorily contained in best-fit equations with a standard deviation of less than 5% during all ventilatory modes and mixtures.

An Improved Calibration Method for a Rotating 2D LIDAR System.

Science.gov (United States)

Zeng, Yadan; Yu, Heng; Dai, Houde; Song, Shuang; Lin, Mingqiang; Sun, Bo; Jiang, Wei; Meng, Max Q-H

2018-02-07

This paper presents an improved calibration method of a rotating two-dimensional light detection and ranging (R2D-LIDAR) system, which can obtain the 3D scanning map of the surroundings. The proposed R2D-LIDAR system, composed of a 2D LIDAR and a rotating unit, is pervasively used in the field of robotics owing to its low cost and dense scanning data. Nevertheless, the R2D-LIDAR system must be calibrated before building the geometric model because there are assembled deviation and abrasion between the 2D LIDAR and the rotating unit. Hence, the calibration procedures should contain both the adjustment between the two devices and the bias of 2D LIDAR itself. The main purpose of this work is to resolve the 2D LIDAR bias issue with a flat plane based on the Levenberg-Marquardt (LM) algorithm. Experimental results for the calibration of the R2D-LIDAR system prove the reliability of this strategy to accurately estimate sensor offsets with the error range from -15 mm to 15 mm for the performance of capturing scans.

Correlated, Static and Dynamic Polarizabilities of Small Molecules. Comparison of Four "Black Box" Methods

DEFF Research Database (Denmark)

Dalskov, Erik K.; Sauer, Stephan P. A.

1998-01-01

Molecular static and dynamic polarizabilities for thirteen small molecules have been calculated using four "black box" ab initio methods, the random phase approximation, RPA, the second-order polarization propagator approximation, SOPPA, the second-order polarization propagator approximation...

Calibration methods for the Hargreaves-Samani equation

Directory of Open Access Journals (Sweden)

Lucas Borges Ferreira

Full Text Available ABSTRACT The estimation of the reference evapotranspiration is an important factor for hydrological studies, design and management of irrigation systems, among others. The Penman Monteith equation presents high precision and accuracy in the estimation of this variable. However, its use becomes limited due to the large number of required meteorological data. In this context, the Hargreaves-Samani equation could be used as alternative, although, for a better performance a local calibration is required. Thus, the aim was to compare the calibration process of the Hargreaves-Samani equation by linear regression, by adjustment of the coefficients (A and B and exponent (C of the equation and by combinations of the two previous alternatives. Daily data from 6 weather stations, located in the state of Minas Gerais, from the period 1997 to 2016 were used. The calibration of the Hargreaves-Samani equation was performed in five ways: calibration by linear regression, adjustment of parameter “A”, adjustment of parameters “A” and “C”, adjustment of parameters “A”, “B” and “C” and adjustment of parameters “A”, “B” and “C” followed by calibration by linear regression. The performances of the models were evaluated based on the statistical indicators mean absolute error, mean bias error, Willmott’s index of agreement, correlation coefficient and performance index. All the studied methodologies promoted better estimations of reference evapotranspiration. The simultaneous adjustment of the empirical parameters “A”, “B” and “C” was the best alternative for calibration of the Hargreaves-Samani equation.

Calibration method of the pulsed X-ray relative sensitivity for ST401 plastic scintillators

International Nuclear Information System (INIS)

Xie Hongwei; Song Guzhou; Wang Kuilu

2011-01-01

The relative sensitivity calibration method of the pulsed X-ray in ST401 plastic scintillator is presented. Experimental relative sensitivity calibrations of the plastic scintillators of different thicknesses from 1 mm to 50 mm are accomplished on the 'Chenguang' pulsed X-ray source and a Co radioactive source, The uncertainty of the calibration data is evaluated, which can be treated as the experimental evidence for the relative sensitivity conversion of ST401 plastic scintillator. (authors)

Hybrid massively parallel fast sweeping method for static Hamilton–Jacobi equations

Energy Technology Data Exchange (ETDEWEB)

Detrixhe, Miles, E-mail: mdetrixhe@engineering.ucsb.edu [Department of Mechanical Engineering (United States); University of California Santa Barbara, Santa Barbara, CA, 93106 (United States); Gibou, Frédéric, E-mail: fgibou@engineering.ucsb.edu [Department of Mechanical Engineering (United States); University of California Santa Barbara, Santa Barbara, CA, 93106 (United States); Department of Computer Science (United States); Department of Mathematics (United States)

2016-10-01

The fast sweeping method is a popular algorithm for solving a variety of static Hamilton–Jacobi equations. Fast sweeping algorithms for parallel computing have been developed, but are severely limited. In this work, we present a multilevel, hybrid parallel algorithm that combines the desirable traits of two distinct parallel methods. The fine and coarse grained components of the algorithm take advantage of heterogeneous computer architecture common in high performance computing facilities. We present the algorithm and demonstrate its effectiveness on a set of example problems including optimal control, dynamic games, and seismic wave propagation. We give results for convergence, parallel scaling, and show state-of-the-art speedup values for the fast sweeping method.

Hybrid massively parallel fast sweeping method for static Hamilton–Jacobi equations

International Nuclear Information System (INIS)

Detrixhe, Miles; Gibou, Frédéric

2016-01-01

The fast sweeping method is a popular algorithm for solving a variety of static Hamilton–Jacobi equations. Fast sweeping algorithms for parallel computing have been developed, but are severely limited. In this work, we present a multilevel, hybrid parallel algorithm that combines the desirable traits of two distinct parallel methods. The fine and coarse grained components of the algorithm take advantage of heterogeneous computer architecture common in high performance computing facilities. We present the algorithm and demonstrate its effectiveness on a set of example problems including optimal control, dynamic games, and seismic wave propagation. We give results for convergence, parallel scaling, and show state-of-the-art speedup values for the fast sweeping method.

Differential computation method used to calibrate the angle-centroid relationship in coaxial reverse Hartmann test

Science.gov (United States)

Li, Xinji; Hui, Mei; Zhao, Zhu; Liu, Ming; Dong, Liquan; Kong, Lingqin; Zhao, Yuejin

2018-05-01

A differential computation method is presented to improve the precision of calibration for coaxial reverse Hartmann test (RHT). In the calibration, the accuracy of the distance measurement greatly influences the surface shape test, as demonstrated in the mathematical analyses. However, high-precision absolute distance measurement is difficult in the calibration. Thus, a differential computation method that only requires the relative distance was developed. In the proposed method, a liquid crystal display screen successively displayed two regular dot matrix patterns with different dot spacing. In a special case, images on the detector exhibited similar centroid distributions during the reflector translation. Thus, the critical value of the relative displacement distance and the centroid distributions of the dots on the detector were utilized to establish the relationship between the rays at certain angles and the detector coordinates. Experiments revealed the approximately linear behavior of the centroid variation with the relative displacement distance. With the differential computation method, we increased the precision of traditional calibration 10-5 rad root mean square. The precision of the RHT was increased by approximately 100 nm.

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

Energy Technology Data Exchange (ETDEWEB)

Yang, Sen; Li, Chengwei, E-mail: heikuanghit@163.com [School of Electrical Engineering and Automation, Harbin Institute of Technology, Harbin 150001 (China)

2016-06-15

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.

Upper Limb Kinematics Using Inertial and Magnetic Sensors: Comparison of Sensor-to-Segment Calibrations

Directory of Open Access Journals (Sweden)

Brice Bouvier

2015-07-01

Full Text Available Magneto-Inertial Measurement Unit sensors (MIMU display high potential for the quantitative evaluation of upper limb kinematics, as they allow monitoring ambulatory measurements. The sensor-to-segment calibration step, consisting of establishing the relation between MIMU sensors and human segments, plays an important role in the global accuracy of joint angles. The aim of this study was to compare sensor-to-segment calibrations for the MIMU-based estimation of wrist, elbow, and shoulder joint angles, by examining trueness (“close to the reference” and precision (reproducibility validity criteria. Ten subjects performed five sessions with three different operators. Three classes of calibrations were studied: segment axes equal to technical MIMU axes (TECH, segment axes generated during a static pose (STATIC, and those generated during functional movements (FUNCT. The calibrations were compared during the maximal uniaxial movements of each joint, plus an extra multi-joint movement. Generally, joint angles presented good trueness and very good precision in the range 5°–10°. Only small discrepancy between calibrations was highlighted, with the exception of a few cases. The very good overall accuracy (trueness and precision of MIMU-based joint angle data seems to be more dependent on the level of rigor of the experimental procedure (operator training than on the choice of calibration itself.

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.

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

International Nuclear Information System (INIS)

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

2014-01-01

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.

Five-hole pitot probe time-mean velocity measurements in confined swirling flows

Science.gov (United States)

Yoon, H. K.; Lilley, D. G.

1983-01-01

Nonswirling and swirling nonreacting flows in an axisymmetric test section with an expansion ratio D/d = 2, which may be equipped with contraction nozzles of area ratios 2 and 4, are investigated. The effects of a number of geometric parameters on the flow-field are investigated, among them side-wall expansion angles of 90 and 45 deg, swirl vane angles of 0, 38, 45, 60, and 70 deg, and contraction nozzle locations L/D = 1 and 2 (if present). Data are acquired by means of a five-hole pitot probe enabling three time-mean velocity components in the axial, radial, and azimuthal directions to be measured. The velocities are extensively plotted and artistic impressions of recirculation zones are set forth. The presence of a swirler is found to shorten the corner recirculation zone and to generate a central recirculation zone followed by a precessing vortex core. A gradual inlet expansion has the effect of encouraging the flow to remain close to the sidewall and shortening the extent of the corner recirculation zone in all cases investigated.

Importance of Calibration Method in Central Blood Pressure for Cardiac Structural Abnormalities.

Science.gov (United States)

Negishi, Kazuaki; Yang, Hong; Wang, Ying; Nolan, Mark T; Negishi, Tomoko; Pathan, Faraz; Marwick, Thomas H; Sharman, James E

2016-09-01

Central blood pressure (CBP) independently predicts cardiovascular risk, but calibration methods may affect accuracy of central systolic blood pressure (CSBP). Standard central systolic blood pressure (Stan-CSBP) from peripheral waveforms is usually derived with calibration using brachial SBP and diastolic BP (DBP). However, calibration using oscillometric mean arterial pressure (MAP) and DBP (MAP-CSBP) is purported to provide more accurate representation of true invasive CSBP. This study sought to determine which derived CSBP could more accurately discriminate cardiac structural abnormalities. A total of 349 community-based patients with risk factors (71±5years, 161 males) had CSBP measured by brachial oscillometry (Mobil-O-Graph, IEM GmbH, Stolberg, Germany) using 2 calibration methods: MAP-CSBP and Stan-CSBP. Left ventricular hypertrophy (LVH) and left atrial dilatation (LAD) were measured based on standard guidelines. MAP-CSBP was higher than Stan-CSBP (149±20 vs. 128±15mm Hg, P curve analyses, MAP-CSBP significantly better discriminated LVH compared with Stan-CSBP (area under the curve (AUC) 0.66 vs. 0.59, P = 0.0063) and brachial SBP (0.62, P = 0.027). Continuous net reclassification improvement (NRI) (P AUC 0.63 vs. 0.56, P = 0.005) and conventional brachial SBP (0.58, P = 0.006), whereas Stan-CSBP provided no better discrimination than conventional brachial BP (P = 0.09). CSBP is calibration dependent and when oscillometric MAP and DBP are used, the derived CSBP is a better discriminator for cardiac structural abnormalities. © American Journal of Hypertension, Ltd 2016. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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.

Method for lateral force calibration in atomic force microscope using MEMS microforce sensor.

Science.gov (United States)

Dziekoński, Cezary; Dera, Wojciech; Jarząbek, Dariusz M

2017-11-01

In this paper we present a simple and direct method for the lateral force calibration constant determination. Our procedure does not require any knowledge about material or geometrical parameters of an investigated cantilever. We apply a commercially available microforce sensor with advanced electronics for direct measurement of the friction force applied by the cantilever's tip to a flat surface of the microforce sensor measuring beam. Due to the third law of dynamics, the friction force of the equal value tilts the AFM cantilever. Therefore, torsional (lateral force) signal is compared with the signal from the microforce sensor and the lateral force calibration constant is determined. The method is easy to perform and could be widely used for the lateral force calibration constant determination in many types of atomic force microscopes. Copyright © 2017 Elsevier B.V. All rights reserved.

An innovative method for coordinate measuring machine one-dimensional self-calibration with simplified experimental process.

Science.gov (United States)

Fang, Cheng; Butler, David Lee

2013-05-01

In this paper, an innovative method for CMM (Coordinate Measuring Machine) self-calibration is proposed. In contrast to conventional CMM calibration that relies heavily on a high precision reference standard such as a laser interferometer, the proposed calibration method is based on a low-cost artefact which is fabricated with commercially available precision ball bearings. By optimizing the mathematical model and rearranging the data sampling positions, the experimental process and data analysis can be simplified. In mathematical expression, the samples can be minimized by eliminating the redundant equations among those configured by the experimental data array. The section lengths of the artefact are measured at arranged positions, with which an equation set can be configured to determine the measurement errors at the corresponding positions. With the proposed method, the equation set is short of one equation, which can be supplemented by either measuring the total length of the artefact with a higher-precision CMM or calibrating the single point error at the extreme position with a laser interferometer. In this paper, the latter is selected. With spline interpolation, the error compensation curve can be determined. To verify the proposed method, a simple calibration system was set up on a commercial CMM. Experimental results showed that with the error compensation curve uncertainty of the measurement can be reduced to 50%.

AFM lateral force calibration for an integrated probe using a calibration grating

International Nuclear Information System (INIS)

Wang, Huabin; Gee, Michelle L.

2014-01-01

Atomic force microscopy (AFM) friction measurements on hard and soft materials remain a challenge due to the difficulties associated with accurately calibrating the cantilever for lateral force measurement. One of the most widely accepted lateral force calibration methods is the wedge method. This method is often used in a simplified format but in so doing sacrifices accuracy. In the present work, we have further developed the wedge method to provide a lateral force calibration method for integrated AFM probes that is easy to use without compromising accuracy and reliability. Raw friction calibration data are collected from a single scan image by continuous ramping of the set point as the facets of a standard grating are scanned. These data are analysed to yield an accurate lateral force conversion/calibration factor that is not influenced by adhesion forces or load deviation. By demonstrating this new calibration method, we illustrate its reliability, speed and ease of execution. This method makes accessible reliable boundary lubrication studies on adhesive and heterogeneous surfaces that require spatial resolution of frictional forces. - Highlights: • We develop a simple and accurate method for lateral force calibration in AFM friction measurements. • We detail the basis of the method and illustrate how to use it and its reliability with example data. • Our method is easy, accurate and accounts for the affects of adhesion on friction measurements. • The method is applicable to integrated probes, as opposed to colloidal probes. • This allows accurate AFM friction measurements on spatially heterogeneous and adhesive surfaces

Micromechanical contact stiffness devices and application for calibrating contact resonance atomic force microscopy

Science.gov (United States)

Rosenberger, Matthew R.; Chen, Sihan; Prater, Craig B.; King, William P.

2017-01-01

This paper reports the design, fabrication, and characterization of micromechanical devices that can present an engineered contact stiffness to an atomic force microscope (AFM) cantilever tip. These devices allow the contact stiffness between the AFM tip and a substrate to be easily and accurately measured, and can be used to calibrate the cantilever for subsequent mechanical property measurements. The contact stiffness devices are rigid copper disks of diameters 2-18 μm integrated onto a soft silicone substrate. Analytical modeling and finite element simulations predict the elastic response of the devices. Measurements of tip-sample interactions during quasi-static force measurements compare well with modeling simulation, confirming the expected elastic response of the devices, which are shown to have contact stiffness 32-156 N m-1. To demonstrate one application, we use the disk sample to calibrate three resonant modes of a U-shaped AFM cantilever actuated via Lorentz force, at approximately 220, 450, and 1200 kHz. We then use the calibrated cantilever to determine the contact stiffness and elastic modulus of three polymer samples at these modes. The overall approach allows cantilever calibration without prior knowledge of the cantilever geometry or its resonance modes, and could be broadly applied to both static and dynamic measurements that require AFM calibration against a known contact stiffness.

A METHOD FOR SELF-CALIBRATION IN SATELLITE WITH HIGH PRECISION OF SPACE LINEAR ARRAY CAMERA

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W. Liu

2016-06-01

Full Text Available At present, the on-orbit calibration of the geometric parameters of a space surveying camera is usually processed by data from a ground calibration field after capturing the images. The entire process is very complicated and lengthy and cannot monitor and calibrate the geometric parameters in real time. On the basis of a large number of on-orbit calibrations, we found that owing to the influence of many factors, e.g., weather, it is often difficult to capture images of the ground calibration field. Thus, regular calibration using field data cannot be ensured. This article proposes a real time self-calibration method for a space linear array camera on a satellite using the optical auto collimation principle. A collimating light source and small matrix array CCD devices are installed inside the load system of the satellite; these use the same light path as the linear array camera. We can extract the location changes of the cross marks in the matrix array CCD to determine the real-time variations in the focal length and angle parameters of the linear array camera. The on-orbit status of the camera is rapidly obtained using this method. On one hand, the camera’s change regulation can be mastered accurately and the camera’s attitude can be adjusted in a timely manner to ensure optimal photography; in contrast, self-calibration of the camera aboard the satellite can be realized quickly, which improves the efficiency and reliability of photogrammetric processing.

Method of energy calibration of the TANSY neutron detectors

International Nuclear Information System (INIS)

Hoek, M.; Drozdowicz, K.; Aronsson, D.

1990-03-01

A method to calibrate an array of scintillation neutron detectors, using a γ source, is presented. The count rate is measured as a function of high voltage at a given discrimination level. The obtained distribution is differentiated and a maximum value is determined which corresponds to the voltage at which the gamma peak passes through the discrimination level. By repeating the measurement at different discrimination levels the experimental dependence between the discrimination level and the high voltage is found as a straight line in a log-log diagram. Two calibration parameter for each detector are determined from a fit of these straight lines. A recalculation from the energy of the used γ source to any other energy is then possible and the obtained relation can be used to calculate discrimination levels and high voltages for each detector. Verification procedures are described. (authors)

Assay of cortisol with a radioimmunoassay method calibrated by isotope dilution-mass spectrometry. A Nordic collaborative study

International Nuclear Information System (INIS)

Lantto, O.; Lindback, B.; Aakvaag, A.; Bjoerkhem, I.; Damkjaer-Nielsen, M.; Pomoell, U.M.; Helsinki University Hospital

1983-01-01

A reference method for serum cortisol, based on isotope dilution-mass spectrometry (ID-MS), was compared with a modified commercial RIA method. The modification solely concerned the calibration standards used in the RIA method. These were replaced by a series of human serum samples, in which the concentration of cortisol had been determined by the reference ID-MS method. Samples were selected to cover the whole range of the standard curve. Serum samples from healthy, untreated subjects with cortisol concentrations 270-1134 nmol/l were analysed with the ID-MS calibrated RIA method in four laboratories, one in each of the four Nordic countries. Mean values based on results from all four laboratories were almost identical with the values obtained with the reference method. Serum samples from 11 patients with endocrine disorders with cortisol concentrations 31-916 nmol/l were analysed in three of the four laboratories. In three of the samples significant differences were observed between the values obtained with the ID-MS and the ID-MS calibrated RIA method. The value obtained with the ID-MS calibrated RIA was however always more accurate than the corresponding value obtained with RIA with the use of a commercial calibration standard. (author)

A Start-up Calibration Method for Generic Current-Steering D/A Converters with Optimal Area Solution

NARCIS (Netherlands)

Radulov, G.I.; Quinn, P.J.; Hegt, J.A.; Roermund, van A.H.M.

2005-01-01

This paper presents a new start-up calibration method for current-steering D/A converters, based on a 1-bit ADC. The paper proposes a new current cell that allows calibration of non-identical current sources by way of a shared calibration apparatus. The current cell uses parallel selfcalibrated unit

Modeling the static fringe field of superconducting magnets.

Science.gov (United States)

Jeglic, P; Lebar, A; Apih, T; Dolinsek, J

2001-05-01

The resonance frequency-space and the frequency gradient-space relations are evaluated analytically for the static fringe magnetic field of superconducting magnets used in the NMR diffusion measurements. The model takes into account the actual design of the high-homogeneity magnet coil system that consists of the main coil and the cryoshim coils and enables a precise calibration of the on-axis magnetic field gradient and the resonance frequency inside and outside of the superconducting coil. Copyright 2001 Academic Press.

In-situ calibration of nuclear-plant platinum resistance thermometers using Johnson noise methods. Final report

International Nuclear Information System (INIS)

Blalock, T.V.; Shepard, R.L.

1983-06-01

Methods for in situ calibration of reactor plant platinum resistance thermometers using Johnson noise measurements were tested in the laboratory and in two operating reactors: Diablo Canyon and Sequoyah. The Johnson noise methods provide an absolute measurement of the thermometer temperature and can be compared with the dc calibration of the thermometers to confirm their calibration without removing the thermometers from the plant coolant loops. Inaccuracies of less than 0.1% were obtained with these methods for ideal situations where the noise measuring equipment could be connected directly to the installed thermometer terminals. For measurements made at the ends of long extension cables, inaccuracies were 0.5 to 1.0%, at best. Extension cables must be optimized and well characterized electrically to achieve such accuracies. Other factors that affect the accuracy of these methods were evaluated

Comparatively Studied Color Correction Methods for Color Calibration of Automated Microscopy Complex of Biomedical Specimens

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T. A. Kravtsova

2016-01-01

Full Text Available The paper considers a task of generating the requirements and creating a calibration target for automated microscopy systems (AMS of biomedical specimens to provide the invariance of algorithms and software to the hardware configuration. The required number of color fields of the calibration target and their color coordinates are mostly determined by the color correction method, for which coefficients of the equations are estimated during the calibration process. The paper analyses existing color calibration techniques for digital imaging systems using an optical microscope and shows that there is a lack of published results of comparative studies to demonstrate a particular useful color correction method for microscopic images. A comparative study of ten image color correction methods in RGB space using polynomials and combinations of color coordinate of different orders was carried out. The method of conditioned least squares to estimate the coefficients in the color correction equations using captured images of 217 color fields of the calibration target Kodak Q60-E3 was applied. The regularization parameter in this method was chosen experimentally. It was demonstrated that the best color correction quality characteristics are provided by the method that uses a combination of color coordinates of the 3rd order. The study of the influence of the number and the set of color fields included in calibration target on color correction quality for microscopic images was performed. Six train sets containing 30, 35, 40, 50, 60 and 80 color fields, and test set of 47 color fields not included in any of the train sets were formed. It was found out that the train set of 60 color fields minimizes the color correction error values for both operating modes of digital camera: using "default" color settings and with automatic white balance. At the same time it was established that the use of color fields from the widely used now Kodak Q60-E3 target does not

An Improved Calibration Method for a Rotating 2D LIDAR System

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Yadan Zeng

2018-02-01

Full Text Available This paper presents an improved calibration method of a rotating two-dimensional light detection and ranging (R2D-LIDAR system, which can obtain the 3D scanning map of the surroundings. The proposed R2D-LIDAR system, composed of a 2D LIDAR and a rotating unit, is pervasively used in the field of robotics owing to its low cost and dense scanning data. Nevertheless, the R2D-LIDAR system must be calibrated before building the geometric model because there are assembled deviation and abrasion between the 2D LIDAR and the rotating unit. Hence, the calibration procedures should contain both the adjustment between the two devices and the bias of 2D LIDAR itself. The main purpose of this work is to resolve the 2D LIDAR bias issue with a flat plane based on the Levenberg–Marquardt (LM algorithm. Experimental results for the calibration of the R2D-LIDAR system prove the reliability of this strategy to accurately estimate sensor offsets with the error range from −15 mm to 15 mm for the performance of capturing scans.

Least square methods and covariance matrix applied to the relative efficiency calibration of a Ge(Li) detector

International Nuclear Information System (INIS)

Geraldo, L.P.; Smith, D.L.

1989-01-01

The methodology of covariance matrix and square methods have been applied in the relative efficiency calibration for a Ge(Li) detector apllied in the relative efficiency calibration for a Ge(Li) detector. Procedures employed to generate, manipulate and test covariance matrices which serve to properly represent uncertainties of experimental data are discussed. Calibration data fitting using least square methods has been performed for a particular experimental data set. (author) [pt

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.

Research on Monte Carlo improved quasi-static method for reactor space-time dynamics

International Nuclear Information System (INIS)

Xu Qi; Wang Kan; Li Shirui; Yu Ganglin

2013-01-01

With large time steps, improved quasi-static (IQS) method can improve the calculation speed for reactor dynamic simulations. The Monte Carlo IQS method was proposed in this paper, combining the advantages of both the IQS method and MC method. Thus, the Monte Carlo IQS method is beneficial for solving space-time dynamics problems of new concept reactors. Based on the theory of IQS, Monte Carlo algorithms for calculating adjoint neutron flux, reactor kinetic parameters and shape function were designed and realized. A simple Monte Carlo IQS code and a corresponding diffusion IQS code were developed, which were used for verification of the Monte Carlo IQS method. (authors)

Static Analysis of Mobile Programs

Science.gov (United States)

2017-02-01

and not allowed, to do. The second issue was that a fully static analysis was never a realistic possibility, because Java , the programming langauge...scale to large programs it had to handle essentially all of the features of Java and could also be used as a general-purpose analysis engine. The...static analysis of imperative languages. • A framework for adding specifications about the behavior of methods, including methods that were

Error Analysis of Relative Calibration for RCS Measurement on Ground Plane Range

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Wu Peng-fei

2012-03-01

Full Text Available Ground plane range is a kind of outdoor Radar Cross Section (RCS test range used for static measurement of full-size or scaled targets. Starting from the characteristics of ground plane range, the impact of environments on targets and calibrators is analyzed during calibration in the RCS measurements. The error of relative calibration produced by the different illumination of target and calibrator is studied. The relative calibration technique used in ground plane range is to place the calibrator on a fixed and auxiliary pylon somewhere between the radar and the target under test. By considering the effect of ground reflection and antenna pattern, the relationship between the magnitude of echoes and the position of calibrator is discussed. According to the different distances between the calibrator and target, the difference between free space and ground plane range is studied and the error of relative calibration is calculated. Numerical simulation results are presented with useful conclusions. The relative calibration error varies with the position of calibrator, frequency and antenna beam width. In most case, set calibrator close to the target may keep the error under control.

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)

Method for calibration measurement in a liquid scintillation counter and carrier used in the method

International Nuclear Information System (INIS)

Reunanen, M.A.

1976-01-01

The present invention relates to a method for use in liquid scintillation measurements to feed an accurately determined amount of radioactive substance to a fluid scintillation system for a calibration measurement. According to the invention an accurately determined amount of radioactive substance is adsorbed to a carrier, which is introduced into the fluid scintillation system. The invention also relates to a carrier for use in the method

A method to derive corpuscular-optics identities as a consequence of the static character of fields

International Nuclear Information System (INIS)

Matyshev, A.A.

2006-01-01

A method to derive identities in static corpuscular optics is described. The essence of the method involves consideration of the particle start time as a parameter. As an example, 12 identities have been derived for a single electrostatic lens in the asymptotic case

A novel PET camera calibration method

International Nuclear Information System (INIS)

Yerian, K.; Hartz, R.K.; Gaeta, J.M.; Marani, S.; Wong, W.H.; Bristow, D.; Mullani, N.A.

1985-01-01

Reconstructed time-of-flight PET images must be corrected for differences in the sensitivity of detector pairs, variations in the TOF gain between groups of detector pairs, and for shifts in the detector-pair timing windows. These calibration values are measured for each detector-pair coincidence line using a positron emitting ring source. The quality of the measured value for a detector pair depends on its statistics. To improve statistics, algorithms are developed which derive individual detector calibration values for efficiency, TOF offsets, and TOF fwhm from the raw detector-pair measurements. For the author's current TOFPET system there are 162,000 detector pairs which are reduced to 720 individual detector values. The data for individual detectors are subsequently recombined, improving the statistical quality of the resultant detector-pair values. In addition, storage requirements are significantly reduced by saving the individual detector values. These parameters are automatically evaluated on a routine basis and problem detectors reported for adjustment or replacement. Decomposing the detector-pair measurements into individual detector values significantly improves the calibration values used to correct camera artifacts in PET imaging

Gravimetric method for in vitro calibration of skin hydration measurements.

Science.gov (United States)

Martinsen, Ørjan G; Grimnes, Sverre; Nilsen, Jon K; Tronstad, Christian; Jang, Wooyoung; Kim, Hongsig; Shin, Kunsoo; Naderi, Majid; Thielmann, Frank

2008-02-01

A novel method for in vitro calibration of skin hydration measurements is presented. The method combines gravimetric and electrical measurements and reveals an exponential dependency of measured electrical susceptance to absolute water content in the epidermal stratum corneum. The results also show that absorption of water into the stratum corneum exhibits three different phases with significant differences in absorption time constant. These phases probably correspond to bound, loosely bound, and bulk water.

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 ...

Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film

Directory of Open Access Journals (Sweden)

Tatsuhiro Gotanda

2016-01-01

Full Text Available Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were −32.336 and −33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.

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...... apart to avoid acoustic interaction. As a part of the project Euromet-792, aiming to investigate and improve methods for secondary free-field calibration of microphones, a sound source suitable for simultaneous secondary free-field calibration has been designed using the Boundary Element Method...... of the Danish Fundamental Metrology Institute (DFM). The design and verification of the source are presented in this communication....

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

is of particular importance to achieve a sound field that reaches both microphones with the same level and that is sufficiently uniform at the microphone positions, in order to reduce the effect of misalignment. An existing sound source has been modeled using the Boundary Element Method, and the simulations have......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...... 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...

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...

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

International Nuclear Information System (INIS)

Gherase, Mihai R; Fleming, David E B

2011-01-01

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 x 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. (note)

A superlinear iteration method for calculation of finite length journal bearing's static equilibrium position

Science.gov (United States)

Zhou, Wenjie; Wei, Xuesong; Wang, Leqin; Wu, Guangkuan

2017-05-01

Solving the static equilibrium position is one of the most important parts of dynamic coefficients calculation and further coupled calculation of rotor system. The main contribution of this study is testing the superlinear iteration convergence method-twofold secant method, for the determination of the static equilibrium position of journal bearing with finite length. Essentially, the Reynolds equation for stable motion is solved by the finite difference method and the inner pressure is obtained by the successive over-relaxation iterative method reinforced by the compound Simpson quadrature formula. The accuracy and efficiency of the twofold secant method are higher in comparison with the secant method and dichotomy. The total number of iterative steps required for the twofold secant method are about one-third of the secant method and less than one-eighth of dichotomy for the same equilibrium position. The calculations for equilibrium position and pressure distribution for different bearing length, clearance and rotating speed were done. In the results, the eccentricity presents linear inverse proportional relationship to the attitude angle. The influence of the bearing length, clearance and bearing radius on the load-carrying capacity was also investigated. The results illustrate that larger bearing length, larger radius and smaller clearance are good for the load-carrying capacity of journal bearing. The application of the twofold secant method can greatly reduce the computational time for calculation of the dynamic coefficients and dynamic characteristics of rotor-bearing system with a journal bearing of finite length.

Fast static field CIPT mapping of unpatterned MRAM film stacks

DEFF Research Database (Denmark)

Kjær, Daniel; Hansen, Ole; Henrichsen, Henrik Hartmann

2015-01-01

Current In-Plane Tunneling (CIPT) method measures both RA and TMR, but the usefulness for uniformity mapping, e.g. for tool optimization, is limited by excessive measurement time. Thus, we develop and demonstrate a fast complementary static magnetic field method focused only on measurement of RA. We...... compare the static field method to the standard CIPT method and find perfect agreement between the extracted RA values and measurement repeatability while the static field method is several times faster. The static field CIPT method is demonstrated for 200 mm wafer mapping showing radial as well...

Method of making self-calibrated displacement measurements

International Nuclear Information System (INIS)

Pedersen, H.N.

1977-01-01

A method for monitoring the displacement of an object having an acoustically reflective surface at least partially submerged in an acoustically conductive medium is described. The reflective surface is designed to have a stepped interface responsive to an incident acoustic pulse to provide separate discrete reflected pulses to a receiving transducer. The difference in the time of flight of the reflected acoustic signals corresponds to the known step height and the time of travel of the signals to the receiving transducer provides a measure of the displacement of the object. Accordingly, the reference step length enables simultaneous calibration of each displacement measurement. 3 claims, 3 figures

Calibrating cellular automaton models for pedestrians walking through corners

Science.gov (United States)

Dias, Charitha; Lovreglio, Ruggiero

2018-05-01

Cellular Automata (CA) based pedestrian simulation models have gained remarkable popularity as they are simpler and easier to implement compared to other microscopic modeling approaches. However, incorporating traditional floor field representations in CA models to simulate pedestrian corner navigation behavior could result in unrealistic behaviors. Even though several previous studies have attempted to enhance CA models to realistically simulate pedestrian maneuvers around bends, such modifications have not been calibrated or validated against empirical data. In this study, two static floor field (SFF) representations, namely 'discrete representation' and 'continuous representation', are calibrated for CA-models to represent pedestrians' walking behavior around 90° bends. Trajectory data collected through a controlled experiment are used to calibrate these model representations. Calibration results indicate that although both floor field representations can represent pedestrians' corner navigation behavior, the 'continuous' representation fits the data better. Output of this study could be beneficial for enhancing the reliability of existing CA-based models by representing pedestrians' corner navigation behaviors more realistically.

An Analysis on a Dynamic Amplifier and Calibration Methods for a Pseudo-Differential Dynamic Comparator

Science.gov (United States)

Paik, Daehwa; Miyahara, Masaya; Matsuzawa, Akira

This paper analyzes a pseudo-differential dynamic comparator with a dynamic pre-amplifier. The transient gain of a dynamic pre-amplifier is derived and applied to equations of the thermal noise and the regeneration time of a comparator. This analysis enhances understanding of the roles of transistor's parameters in pre-amplifier's gain. Based on the calculated gain, two calibration methods are also analyzed. One is calibration of a load capacitance and the other is calibration of a bypass current. The analysis helps designers' estimation for the accuracy of calibration, dead-zone of a comparator with a calibration circuit, and the influence of PVT variation. The analyzed comparator uses 90-nm CMOS technology as an example and each estimation is compared with simulation results.

Methods for calibrating radioactivity well logging tools

International Nuclear Information System (INIS)

Waggoner, J.A.; Turcotte, R.E.; Hunt-Grubbe, R.H.

1981-01-01

Field-calibrating of well-logging tools is achieved by means of a sleeve, which has radioactive material distributed therein, and which envelopes the portion of the tool housing containing the detector. Accurate calibration can be performed and the source can be made considerably weaker than those now in use as it can be brought very close to the detector thus lessening errors. (U.K.)

Influence of Loading Rate on the Calibration of Instrumented Charpy Strikers

Energy Technology Data Exchange (ETDEWEB)

Lucon, E.; Scibetta, M.; McColskey, D.; McCowan, C.

2009-01-15

One of the key factors for obtaining reliable instrumented Charpy results is the calibration of the instrumented striker. The conventional approach for establishing an analytical relationship between strain gage output and force applied to the transducer is the static calibration, which is preferably performed with the striker installed in the pendulum assembly. However, the response of an instrumented striker under static force application may sometimes differ significantly from its dynamic performance during an actual Charpy test. This is typically reflected in a large difference between absorbed energy returned by the pendulum encoder (KV) and calculated under the instrumented force/displacement test record (Wt). Such difference can be either minimized by optimizing the striker design or analytically removed by adjusting forces and displacements until KV = Wt (the so-called 'Dynamic Force Adjustment'). This study investigates the influence of increasing force application rates on the force/voltage characteristics of two instrumented strikers, one at NIST in Boulder, CO and one at SCK-CEN in Mol, Belgium.

Experimental data report for transient flow calibration facility tests IIIA101, IIIA102, IIIA201, and IIIA202

International Nuclear Information System (INIS)

Wambach, J.L.

1980-01-01

Thermal-hydraulic response data are presented for the transient performance tests of an ECC pitot tube rake (IIIA201, IIIA202) and both an ECC pitot tube rake and modular drag disc-turbine transducer (DTT) rake (IIIA101, IIIA102). The tests were conducted in a system which provided full scale simulation of the pressure vessel and intact loop cold leg piping of the Loss of Fluid Test Facility (LOFT). A load cell system was used to provide a reference mass flow rate measurement

Method for Statically Checking an Object-oriented Computer Program Module

Science.gov (United States)

Bierhoff, Kevin M. (Inventor); Aldrich, Jonathan (Inventor)

2012-01-01

A method for statically checking an object-oriented computer program module includes the step of identifying objects within a computer program module, at least one of the objects having a plurality of references thereto, possibly from multiple clients. A discipline of permissions is imposed on the objects identified within the computer program module. The permissions enable tracking, from among a discrete set of changeable states, a subset of states each object might be in. A determination is made regarding whether the imposed permissions are violated by a potential reference to any of the identified objects. The results of the determination are output to a user.

Research on the method of establishing the total radiation meter calibration device

Science.gov (United States)

Gao, Jianqiang; Xia, Ming; Xia, Junwen; Zhang, Dong

2015-10-01

Pyranometer is an instrument used to measure the solar radiation, according to pyranometer differs as installation state, can be respectively measured total solar radiation, reflected radiation, or with the help of shading device for measuring scattering radiation. Pyranometer uses the principle of thermoelectric effect, inductive element adopts winding plating type multi junction thermopile, its surface is coated with black coating with high absorption rate. Hot junction in the induction surface, while the cold junction is located in the body, the cold and hot junction produce thermoelectric potential. In the linear range, the output signal is proportional to the solar irradiance. Traceability to national meteorological station, as the unit of the national legal metrology organizations, the responsibility is to transfer value of the sun and the earth radiation value about the national meteorological industry. Using the method of comparison, with indoor calibration of solar simulator, at the same location, standard pyranometer and measured pyranometer were alternately measured radiation irradiance, depending on the irradiation sensitivity standard pyranometer were calculated the radiation sensitivity of measured pyranometer. This paper is mainly about the design and calibration method of the pyranometer indoor device. The uncertainty of the calibration result is also evaluated.

Development of methods to predict both the dynamic and the pseudo-static response of secondary structures subjected to seismic excitations

International Nuclear Information System (INIS)

Subudhi, M.; Bezler, P.

1984-01-01

Multiple independent support excitation time history formulations have been used to investigate simplified methods to predict the inertial (or dynamic) component of response as well as the pseudo-static (or static) component of response of secondary structures subjected to seismic excitations. For the dynamic component the independent response spectrum method is used with current industry practice for the modal and direction of excitation combinations being adopted and various procedures for the group combination and sequence being investigated. SRSS combination between support groups is found to yield satisfactory results. For the static component, support grouping by elevation for preliminary design followed by support grouping by attachment point for final design assure overall safety in the design

Method of calibrating a fluid-level measurement system

Science.gov (United States)

Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

2010-01-01

A method of calibrating a fluid-level measurement system is provided. A first response of the system is recorded when the system's sensor(s) is (are) not in contact with a fluid of interest. A second response of the system is recorded when the system's sensor(s) is (are) fully immersed in the fluid of interest. Using the first and second responses, a plurality of expected responses of the system's sensor(s) is (are) generated for a corresponding plurality of levels of immersion of the sensor(s) in the fluid of interest.

A static analysis method to determine the availability of kinetic energy from wind turbines

NARCIS (Netherlands)

Rawn, B.G.; Gibescu, M.; Kling, W.L.

2010-01-01

This paper introduces definitions and an analysis method for estimating how much kinetic energy can be made available for inertial response from a wind turbine over a year, and how much energy capture must be sacrificed to do so. The analysis is based on the static characteristics of wind turbines,

Pitot-pressure distributions of the flow field of a delta-wing orbiter

Science.gov (United States)

Cleary, J. W.

1972-01-01

Pitot pressure distributions of the flow field of a 0.0075-scale model of a typical delta wing shuttle orbiter are presented. Results are given for the windward and leeward sides on centerline in the angle-of-attack plane from wind tunnel tests conducted in air. Distributions are shown for three axial stations X/L = .35, .60, and .98 and for angles of attack from 0 to 60 deg. The tests were made at a Mach number of 7.4 and for Reynolds numbers based on body length from 1,500,000 to 9,000,000. The windward distributions at the two survey stations forward of the body boat tail demonstrate the compressive aspects of the flow from the shock wave to the body. Conversely, the distributions at the aft station display an expansion of the flow that is attributed to body boat tail. On the lee side, results are given at low angles of attack that illustrate the complicating aspects of the canopy on the flow field, while results are given to show the effects of flow separation at high angles of attack.

Calibration of reference KAP-meters at SSDL and cross calibration of clinical KAP-meters

International Nuclear Information System (INIS)

Hetland, Per O.; Friberg, Eva G.; Oevreboe, Kirsti M.; Bjerke, Hans H.

2009-01-01

In the summer of 2007 the secondary standard dosimetry laboratory (SSDL) in Norway established a calibration service for reference air-kerma product meter (KAP-meter). The air-kerma area product, PKA, is a dosimetric quantity that can be directly related to the patient dose and used for risk assessment associated with different x-ray examinations. The calibration of reference KAP-meters at the SSDL gives important information on parameters influencing the calibration factor for different types of KAP-meters. The use of reference KAP-meters calibrated at the SSDL is an easy and reliable way to calibrate or verify the PKA indicated by the x-ray equipment out in the clinics. Material and methods. Twelve KAP-meters were calibrated at the SSDL by use of the substitution method at five diagnostic radiation qualities (RQRs). Results. The calibration factors varied from 0.94 to 1.18. The energy response of the individual KAP-meters varied by a total of 20% between the different RQRs and the typical chamber transmission factors ranged from 0.78 to 0.91. Discussion. It is important to use a calibrated reference KAP-meter and a harmonised calibration method in the PKA calibration in hospitals. The obtained uncertainty in the PKA readings is comparable with other calibration methods if the information in the calibration certificate is correct used, corrections are made and proper positioning of the KAP-chamber is performed. This will ensure a reliable estimate of the patient dose and a proper optimisation of conventional x-ray examinations and interventional procedures

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.

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

International Nuclear Information System (INIS)

Kim, Sang In; Kim, Bong Hwan; Kim, Jang Lyul; Lee, Jung Il

2015-01-01

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 252 Californium ( 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

Calibration of resistance factors for drilled shafts for the new FHWA design method.

Science.gov (United States)

2013-01-01

The Load and Resistance Factor Design (LRFD) calibration of deep foundation in Louisiana was first completed for driven piles (LTRC Final Report 449) in May 2009 and then for drilled shafts using 1999 FHWA design method (ONeill and Reese method) (...

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

International Nuclear Information System (INIS)

Kudzia, D.; Wilczynska, B.; 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

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

Where Does Road Salt Go - a Static Salt Model

Science.gov (United States)

Yu, C. W.; Liu, F.; Moriarty, V. W.

2017-12-01

Each winter, more than 15 million tons of road salt is applied in the United States for the de-icing purpose. Considerable amount of chloride in road salt flows into streams/drainage systems with the snow melt runoff and spring storms, and eventually goes into ecologically sensitive low-lying areas in the watershed, such as ponds and lakes. In many watersheds in the northern part of US, the chloride level in the water body has increased significantly in the past decades, and continues an upward trend. The environmental and ecological impact of the elevated chloride level can no longer be ignored. However although there are many studies on the biological impact of elevated chloride levels, there are few investigations on how the spatially distributed road salt application affects various parts of the watershed. In this presentation, we propose a static road salt model as a first-order metric to address spacial distribution of salt loading. Derived from the Topological Wetness Index (TWI) in many hydrological models, this static salt model provides a spatial impact as- sessment of road salt applications. To demonstrate the effectiveness of the static model, National Elevation Dataset (NED) of ten-meter resolution of Lake George watershed in New York State is used to generate the TWI, which is used to compute a spatially dis- tributed "salt-loading coefficient" of the whole watershed. Spatially varying salt applica- tion rate is then aggregated, using the salt-loading coefficients as weights, to provide salt loading assessments of streams in the watershed. Time-aggregated data from five CTD (conductivity-temperature-depth) sensors in selected streams are used for calibration. The model outputs and the sensor data demonstrate a strong linear correlation, with the R value of 0.97. The investigation shows that the static modeling approach may provide an effective method for the understanding the input and transport of road salt to within watersheds.

SU-F-BRA-09: New Efficient Method for Xoft Axxent Electronic Brachytherapy Source Calibration by Pre-Characterizing Surface Applicators

Energy Technology Data Exchange (ETDEWEB)

Pai, S [iCAD Inc., Los Gatos, CA (United States)

2015-06-15

Purpose: The objective is to improve the efficiency and efficacy of Xoft™ Axxent™ electronic brachytherapy (EBT) calibration of the source & surface applicator using AAPM TG-61 formalism. Methods: Current method of Xoft EBT source calibration involves determination of absolute dose rate of the source in each of the four conical surface applicators using in-air chamber measurements & TG61 formalism. We propose a simplified TG-61 calibration methodology involving initial characterization of surface cone applicators. This is accomplished by calibrating dose rates for all 4 surface applicator sets (for 10 sources) which establishes the “applicator output ratios” with respect to the selected reference applicator (20 mm applicator). After the initial time, Xoft™ Axxent™ source TG61 Calibration is carried out only in the reference applicator. Using the established applicator output ratios, dose rates for other applicators will be calculated. Results: 200 sources & 8 surface applicator sets were calibrated cumulatively using a Standard Imaging A20 ion-chamber in accordance with manufacturer-recommended protocols. Dose rates of 10, 20, 35 & 50mm applicators were normalized to the reference (20mm) applicator. The data in Figure 1 indicates that the normalized dose rate variation for each applicator for all 200 sources is better than ±3%. The average output ratios are 1.11, 1.02 and 0.49 for the 10 mm,35 mm and 50 mm applicators, respectively, which are in good agreement with the manufacturer’s published output ratios of 1.13, 1.02 and 0.49. Conclusion: Our measurements successfully demonstrate the accuracy of a new calibration method using a single surface applicator for Xoft EBT sources and deriving the dose rates of other applicators. The accuracy of the calibration is improved as this method minimizes the source position variation inside the applicator during individual source calibrations. The new method significantly reduces the calibration time to less

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

Calibration of Nanopositioning Stages

Directory of Open Access Journals (Sweden)

Ning Tan

2015-12-01

Full Text Available Accuracy is one of the most important criteria for the performance evaluation of micro- and nanorobots or systems. Nanopositioning stages are used to achieve the high positioning resolution and accuracy for a wide and growing scope of applications. However, their positioning accuracy and repeatability are not well known and difficult to guarantee, which induces many drawbacks for many applications. For example, in the mechanical characterisation of biological samples, it is difficult to perform several cycles in a repeatable way so as not to induce negative influences on the study. It also prevents one from controlling accurately a tool with respect to a sample without adding additional sensors for closed loop control. This paper aims at quantifying the positioning repeatability and accuracy based on the ISO 9283:1998 standard, and analyzing factors influencing positioning accuracy onto a case study of 1-DoF (Degree-of-Freedom nanopositioning stage. The influence of thermal drift is notably quantified. Performances improvement of the nanopositioning stage are then investigated through robot calibration (i.e., open-loop approach. Two models (static and adaptive models are proposed to compensate for both geometric errors and thermal drift. Validation experiments are conducted over a long period (several days showing that the accuracy of the stage is improved from typical micrometer range to 400 nm using the static model and even down to 100 nm using the adaptive model. In addition, we extend the 1-DoF calibration to multi-DoF with a case study of a 2-DoF nanopositioning robot. Results demonstrate that the model efficiently improved the 2D accuracy from 1400 nm to 200 nm.

Beyond discrimination: A comparison of calibration methods and clinical usefulness of predictive models of readmission risk.

Science.gov (United States)

Walsh, Colin G; Sharman, Kavya; Hripcsak, George

2017-12-01

Prior to implementing predictive models in novel settings, analyses of calibration and clinical usefulness remain as important as discrimination, but they are not frequently discussed. Calibration is a model's reflection of actual outcome prevalence in its predictions. Clinical usefulness refers to the utilities, costs, and harms of using a predictive model in practice. A decision analytic approach to calibrating and selecting an optimal intervention threshold may help maximize the impact of readmission risk and other preventive interventions. To select a pragmatic means of calibrating predictive models that requires a minimum amount of validation data and that performs well in practice. To evaluate the impact of miscalibration on utility and cost via clinical usefulness analyses. Observational, retrospective cohort study with electronic health record data from 120,000 inpatient admissions at an urban, academic center in Manhattan. The primary outcome was thirty-day readmission for three causes: all-cause, congestive heart failure, and chronic coronary atherosclerotic disease. Predictive modeling was performed via L1-regularized logistic regression. Calibration methods were compared including Platt Scaling, Logistic Calibration, and Prevalence Adjustment. Performance of predictive modeling and calibration was assessed via discrimination (c-statistic), calibration (Spiegelhalter Z-statistic, Root Mean Square Error [RMSE] of binned predictions, Sanders and Murphy Resolutions of the Brier Score, Calibration Slope and Intercept), and clinical usefulness (utility terms represented as costs). The amount of validation data necessary to apply each calibration algorithm was also assessed. C-statistics by diagnosis ranged from 0.7 for all-cause readmission to 0.86 (0.78-0.93) for congestive heart failure. Logistic Calibration and Platt Scaling performed best and this difference required analyzing multiple metrics of calibration simultaneously, in particular Calibration

Static and dynamic efficiency of irreversible health care investments under alternative payment rules.

Science.gov (United States)

Levaggi, R; Moretto, M; Pertile, P

2012-01-01

The paper studies the incentive for providers to invest in new health care technologies under alternative payment systems, when the patients' benefits are uncertain. If the reimbursement by the purchaser includes both a variable (per patient) and a lump-sum component, efficiency can be ensured both in the timing of adoption (dynamic) and the intensity of use of the technology (static). If the second instrument is unavailable, a trade-off may emerge between static and dynamic efficiency. In this context, we also discuss how the regulator could use control of the level of uncertainty faced by the provider as an instrument to mitigate the trade-off between static and dynamic efficiency. Finally, we calibrate the model to study a specific technology and estimate the cost of a regulatory failure. Copyright © 2011 Elsevier B.V. All rights reserved.

CURVE LSFIT, Gamma Spectrometer Calibration by Interactive Fitting Method

International Nuclear Information System (INIS)

Olson, D.G.

1992-01-01

1 - Description of program or function: CURVE and LSFIT are interactive programs designed to obtain the best data fit to an arbitrary curve. CURVE finds the type of fitting routine which produces the best curve. The types of fitting routines available are linear regression, exponential, logarithmic, power, least squares polynomial, and spline. LSFIT produces a reliable calibration curve for gamma ray spectrometry by using the uncertainty value associated with each data point. LSFIT is intended for use where an entire efficiency curve is to be made starting at 30 KeV and continuing to 1836 KeV. It creates calibration curves using up to three least squares polynomial fits to produce the best curve for photon energies above 120 KeV and a spline function to combine these fitted points with a best fit for points below 120 KeV. 2 - Method of solution: The quality of fit is tested by comparing the measured y-value to the y-value calculated from the fitted curve. The fractional difference between these two values is printed for the evaluation of the quality of the fit. 3 - Restrictions on the complexity of the problem - Maxima of: 2000 data points calibration curve output (LSFIT) 30 input data points 3 least squares polynomial fits (LSFIT) The least squares polynomial fit requires that the number of data points used exceed the degree of fit by at least two

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

Near surface illumination method to detect particle size information by optical calibration free remission measurements

Science.gov (United States)

Stocker, Sabrina; Foschum, Florian; Kienle, Alwin

2017-07-01

A calibration free method to detect particle size information is presented. A possible application for such measurements is the investigation of raw milk since there not only the fat and protein content varies but also the fat droplet size. The newly developed method is sensitive to the scattering phase function, which makes it applicable to many other applications, too. By simulating the light propagation by use of Monte Carlo simulations, a calibration free device can be developed from this principle.

The systematic error of temperature noise correlation measurement method and self-calibration

International Nuclear Information System (INIS)

Tian Hong; Tong Yunxian

1993-04-01

The turbulent transport behavior of fluid noise and the nature of noise affect on the velocity measurement system have been studied. The systematic error of velocity measurement system is analyzed. A theoretical calibration method is proposed, which makes the velocity measurement of time-correlation as an absolute measurement method. The theoretical results are in good agreement with experiments

Preliminary Airworthiness Evaluation AH-1S Helicopter with OGEE Tip Shape Rotor Blades

Science.gov (United States)

1980-05-01

ENGINEER PROJECT PILOT HENRY ARNAIZ PROJECT ENGINEER DTIC MAY 1980 ELECTEV SEP 2 I8 Approved for public release; distribution unlimited. A UNITED STATES...compressibility effects between flights. 7. Airspeed and altitude were obtained from a boom-mounted pitot -static probe. Corrections for position error

A new detection method used to calibrate Fabry-Perot interferometers in the infrared range

International Nuclear Information System (INIS)

Talvard, M.; Javon, C.; Garcin, M.; Thouvenin, D.

1993-06-01

Fabry-Perot interferometers are routinely used in the Tore Supra Tokamak in order to measure the time evolution of the electron temperature of the confined plasmas. Calibration of such interferometers requires the detection of very low DC levels (0.1 nV) with signal-to-noise ratios less than 10 -5 , which is generally not compatible with standard detection methods. A new correlation method to achieve this absolute calibration is proposed. It is based on a proper noise auto-correlation technique combined with an optimized signal filtering involving Fourier analysis. The advantages of the method are detailed and experimentally compared to standard averaging techniques, such as coherent addition and synchronous detection. The method can be used in a more general context every time very small amplitude signals are to be measured

A standardized method for the calibration of thermodynamic data for the prediction of gas chromatographic retention times.

Science.gov (United States)

McGinitie, Teague M; Ebrahimi-Najafabadi, Heshmatollah; Harynuk, James J

2014-02-21

A new method for calibrating thermodynamic data to be used in the prediction of analyte retention times is presented. The method allows thermodynamic data collected on one column to be used in making predictions across columns of the same stationary phase but with varying geometries. This calibration is essential as slight variances in the column inner diameter and stationary phase film thickness between columns or as a column ages will adversely affect the accuracy of predictions. The calibration technique uses a Grob standard mixture along with a Nelder-Mead simplex algorithm and a previously developed model of GC retention times based on a three-parameter thermodynamic model to estimate both inner diameter and stationary phase film thickness. The calibration method is highly successful with the predicted retention times for a set of alkanes, ketones and alcohols having an average error of 1.6s across three columns. Copyright © 2014 Elsevier B.V. All rights reserved.

Method of calibration for portable detectors of ionizing radiation

International Nuclear Information System (INIS)

Leal, Carlos; Carrizales, Lila; Guacaran, Douglas; Moreno, Ailed; Duran, Jose

2008-01-01

Full text: The LSCD is beginning a process of accreditation by the national authority of Venezuela (CENCAMER), so we felt the need to modify existing protocols calibration, suggested by the IAEA (Technical Reports Series No 133) to be adjusted in accordance with international standards of ISO 17025 EA-4/02 and Mexican standard NOM-021-NUCL-2002, adapting the calibration procedure of portable radiation detectors to those standards. The procedure used in the LSCD, conducts an intercomparison between measures between the standard reference and to calibrate the instrument, thus verifying the correct operation of the equipment and its usefulness to the individual or environmental radiation monitoring, not to exceed the limits primary for the public and occupationally Staff Exposed (POE), and propose a simple way to perform this calibration procedure and comply with the standard international and national standards, ensuring the proper functioning of the instruments calibrated. One of the calculations that has proven to be a useful tool in the verification of the conditions of operating the same, it is uncertainty, this procedure allows to characterize the response of individual detector, depending on the constraints specified by the manufacturer, to optimize the calibration is necessary to consider the multiple factors that can affect the measure and evaluate the response of the same, so it is vitally important estimating the typical uncertainty associated with the calibration technique employed, but this calculation is not trivial, depends on the type of detector found usually between 5% to 20%, both in uncertainty as the linearity, which are the parameters that are set to consider an instrument in good or bad condition. Typical are calibrated are: monitors air Geiger-Muller, Ionization cameras, detector of Neutron's, Proportional Counter, Personal dosimeters. (author)

Quantization of the Lee static model by the Bogolyubov transformation method

International Nuclear Information System (INIS)

Bornyakov, V.G.

1984-01-01

The Lee static strong-coupling model is studied. The model permits to find an exact solution for the state vector of the system and for the scattering matrix in the first permanent order of expansion in the inverse value of the coupling constant. The Bogolyubov method has been applied to quantize the Lee model with a hamiltonian, provided a high classical constituent of a boson field exists. Ground state of the system and scattering matrix from the obtained bound state are found. The way to avoid additional zero modes arising at Bogolyubov transformation for creation and annihilation operators is shown

One step geometrical calibration method for optical coherence tomography

International Nuclear Information System (INIS)

Díaz, Jesús Díaz; Ortmaier, Tobias; Stritzel, Jenny; Rahlves, Maik; Reithmeier, Eduard; Roth, Bernhard; Majdani, Omid

2016-01-01

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)

Dew Point Calibration System Using a Quartz Crystal Sensor with a Differential Frequency Method.

Science.gov (United States)

Lin, Ningning; Meng, Xiaofeng; Nie, Jing

2016-11-18

In this paper, the influence of temperature on quartz crystal microbalance (QCM) sensor response during dew point calibration is investigated. The aim is to present a compensation method to eliminate temperature impact on frequency acquisition. A new sensitive structure is proposed with double QCMs. One is kept in contact with the environment, whereas the other is not exposed to the atmosphere. There is a thermal conductivity silicone pad between each crystal and a refrigeration device to keep a uniform temperature condition. A differential frequency method is described in detail and is applied to calibrate the frequency characteristics of QCM at the dew point of -3.75 °C. It is worth noting that frequency changes of two QCMs were approximately opposite when temperature conditions were changed simultaneously. The results from continuous experiments show that the frequencies of two QCMs as the dew point moment was reached have strong consistency and high repeatability, leading to the conclusion that the sensitive structure can calibrate dew points with high reliability.

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.

Quasi-static method and finite element method for obtaining the modifications of the spontaneous emission rate and energy level shift near a plasmonic nanostructure.

Science.gov (United States)