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1

Calibration of Magnetometer for Small Satellites Using Neural Network

100%

Kliment T., Praslička D., Lipovský P., Draganová K., Závodský O.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

1129-1131

EN

The article presents the scalar calibration method that uses a neural network for the determination of parameters of the inverse model of the vector magnetometer. Utilization of the one layered, feed-forward neural network with the back propagation algorithm has suppressed the systematic errors of the vector magnetometers, namely the multiplicative, additive, orthogonality and linearity errors. Methodology shown in the article was designed and used for a pre-flight calibration of the magnetometer used in the first Slovak satellite skCUBE, where the magnetometer performs stabilization and navigation tasks. The experiment was performed in a 3D Helmholtz coil system, where the Earth magnetic field was suppressed and at the same time the stimulation field was created. Suppression of the Earth magnetic field was achieved by special positioning of the satellite. Honeywell HMC 5883L was used for the verification of the methodology.

2

Evaluation of Uncertainty Contributions of Measurement Surface and Number of Microphone Positions in Determination of Sound Power Levels

63%

Bilgic E., Mutaf H., Kirbas C., Sadikoglu E.

Acta Physica Polonica A

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2017

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vol. 132

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issue 3

642-649

EN

Sound power level of a noise source is determined by means of sound pressure level or sound intensity level measurements performed in accordance to relevant ISO standards. The determination of sound power level according to ISO 3744, 3745 and 3746 standards is used for free field or for approximated free field conditions. Kinds of measurement surfaces, enveloping the noise source, number of microphones and their positions over the measurement surface are stated in the applied ISO standard. The effects of measurement surface and number of microphone positions on the determination of sound power level were investigated theoretically. As a measurement surface; hemisphere, parallelepiped rectangular box and cylindrical surfaces were selected. Key and additional microphone positions were taken into account in the calculations as well. Sound pressure levels of a commercially available reference sound source were measured in hemi-anechoic room using FFT with 4 Hz steps and also at 1/1, 1/3, 1/12 and 1/24 octave bands for all surfaces defined in ISO 3744 and 3746 standards. Sound power level, directivity index and uncertainty contributions resulting from measurement surfaces and number of microphone positions were calculated by using data obtained in measurements. In this paper the theoretical and experimental results are presented.

3

Determination of Pulse Width and Pulse Amplitude Characteristics of Materials Used in Pendulum Type Shock Calibration Device

63%

Bilgic E.

Acta Physica Polonica A

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2017

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vol. 132

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issue 3

857-860

EN

Calibration of shock and vibration transducers is performed by using the methods described in ISO 16063-13 and 16063-22 standards, at primary and secondary levels respectively. At secondary level, the devices, generating mechanical shock, are pendulum shock calibrator, dropball shock calibrator, pneumatically operated piston shock calibrator and Hopkinson bar shock calibrator. The main parameters and requirements of the shock calibrator devices, named here, are also given in ISO 16063-22 standard. Pulse width and pulse amplitude are the important parameters in calibration of the shock and vibration transducers. Pulse width and shape depend on the material properties. In this paper the determination of pulse width and pulse amplitude characteristics of materials used in pendulum type shock calibration device, designed in TUBİTAK UME, is presented.

4

Estimation of Calibration Uncertainties in the Detector-Based Photometric Calibrations

51%

Sametoglu F.

Acta Physica Polonica A

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2008

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vol. 114

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issue 4

881-901

EN

Uncertainty evaluations in the photometric calibrations and established uncertainty budgets at National Metrology Institute of Turkey (TUBITAK-UME) are presented. Uncertainty analyses are cover calibrations of the luminous intensity, the luminous flux and the luminance properties of the optical light source. The combined uncertainty in each photometric calibration was evaluated using developed uncertainty models. The degrees of freedom in each input and output quantities were also determined. The coefficient of uncertainty contribution h(y,x_i) was finally determined to present the dominant and less important contributions.

5

Time Calibration of the J-PET Detector

51%

Skurzok M., Silarski M., Alfs D., Białas P., Shivani, Curceanu C., Czerwiński E., Dulski K., Gajos A., Głowacz B., Gorgol M., Hiesmayr B., Jasińska B., Kisielewska-Kamińska D., Korcyl G., Kowalski P., Kozik T., Krawczyk N., Krzemień W., Kubicz E., Mohammed M., Pawlik-Niedźwiecka M., Niedźwiecki S., Pałka M., Raczyński L., Raj J., Rudy Z., Sharma N., Sharma S., Shopa R., Wieczorek A., Wiślicki W., Zgardzińska B., Zieliński M., Moskal P.

Acta Physica Polonica A

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2017

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vol. 132

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issue 5

1641-1644

EN

The Jagiellonian positron emission tomograph project carried out in the Institute of Physics of the Jagiellonian University is focused on construction and tests of the first prototype of PET scanner for medical diagnostic which allows for the simultaneous 3D imaging of the whole human body using organic scintillators. The J-PET prototype consists of 192 scintillator strips forming three cylindrical layers which are optimized for the detection of photons from the electron-positron annihilation with high time-and high angular resolutions. In this article we present time calibration and synchronization of the whole J-PET detection system by irradiating each single detection module with a ²²Na source and a small detector providing common reference time for synchronization of all the modules.

6

Improvement of Electronic Compass Accuracy Based on Magnetometer and Accelerometer Calibration

45%

Šipoš M., Roháč J., Nováček P.

Acta Physica Polonica A

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2012

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vol. 121

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issue 4

945-949

EN

This paper describes the process used for an electronic compass compensation according to accelerometer based tilt evaluation. Tilt angles have to be estimated first for sensed magnetic vector components to be aligned and horizontal components evaluated. Therefore the precision of accelerometer based tilt angles plays a key role in this whole process as well as the magnetometer characteristics. Hence accelerometers plus magnetometers have to be calibrated to improve the accuracy of a tilt and an azimuth angle evaluation. The calibration uses Thin-Shell method to determine sensor error models. Both the effect of calibration and precision of estimated error models have been observed and are presented. The electronic compass consisted of tri-axial magnetometer and tri-axial accelerometer contained in the Inertial Measurement Unit ADIS16405 from Analog Devices manufacturer.

7

Neural Approximation of Empirical Functions

38%

Roj J.

Acta Physica Polonica A

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2013

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vol. 124

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issue 3

554-557

EN

The paper presents the results of simulation studies of selected neural network structures used for non-linear function approximation based on a limited accuracy data. There was performed the analysis of the interdependence of the network structure and the size of the set of learning patterns. The approximation inaccuracy was expressed by the uncertainty interval width. The approximation properties of the neural method were compared with those of the piece-wise linear and polynomial: "cubic" and "spline" methods.

8

Normal Force Calibration Method Used for Calibration οf Atomic Force Microscope

38%

Ekwińska M., Rymuza Z.

Acta Physica Polonica A

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2009

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vol. 116

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issue S

S-78-S-81

EN

Development of new technologies for micro/nanostructures is connected with introduction of new materials or with application of already existing ones in micro- and nanoscale. Unfortunately material parameters in macro- and micro/nanoscale are not the same. For this reason it has become crucial to identify nanomechanical properties of materials commonly used in micro- and nanostructures technology. One of the tests used for that purpose is nanowear test made on the atomic force microscope. However, to obtain quantitative results of measurements, precision calibration step is necessary. In this paper a novel approach to calibration of normal force, which is acting on the tip of an atomic force microscope cantilever, is discussed. Presented method is based on application of known normal force directly on the tip using special test structure. Such an approach allows for measurements of nanowear parameters (force, displacement) with uncertainty better than ± 3%. Authors present and discuss different constructions of calibration samples. A comparison of described method with already existing ones is also presented.

Refine search results

Calibration of Magnetometer for Small Satellites Using Neural Network

Evaluation of Uncertainty Contributions of Measurement Surface and Number of Microphone Positions in Determination of Sound Power Levels

Determination of Pulse Width and Pulse Amplitude Characteristics of Materials Used in Pendulum Type Shock Calibration Device

Estimation of Calibration Uncertainties in the Detector-Based Photometric Calibrations

Time Calibration of the J-PET Detector

Improvement of Electronic Compass Accuracy Based on Magnetometer and Accelerometer Calibration

Neural Approximation of Empirical Functions

Normal Force Calibration Method Used for Calibration οf Atomic Force Microscope