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1

Leak Detection in Waterworks: Comparison Between STFT and FFT with an Overcoming of Limitations

Lay-Ekuakille A., Griffo G., Visconti P., Primiceri P., Velazquez R.

Metrology and Measurement Systems

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2017

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Vol. 24, nr 4

631--644

EN

Detection of leakages in pipelines is a matter of continuous research because of the basic importance for a waterworks system is finding the point of the pipeline where a leak is located and - in some cases - a nature of the leak. There are specific difficulties in finding leaks by using spectral analysis techniques like FFT (Fast Fourier Transform), STFT (Short Term Fourier Transform), etc. These difficulties arise especially in complicated pipeline configurations, e.g. a zigzag one. This research focuses on the results of a new algorithm based on FFT and comparing them with a developed STFT technique. Even if other techniques are used, they are costly and difficult to be managed. Moreover, a constraint in the leak detection is the pipeline diameter because it influences accuracy of the adopted algorithm. FFT and STFT are not fully adequate for complex configurations dealt with in this paper, since they produce ill-posed problems with an increasing uncertainty. Therefore, an improved Tikhonov technique has been implemented to reinforce FFT and STFT for complex configurations of pipelines. Hence, the proposed algorithm overcomes the aforementioned difficulties due to applying a linear algebraic approach.

2

Współczesne sensory magnetyczne w zastosowaniach nawigacyjnych

Felski A.

Logistyka

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2014

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nr 3

1676--1687

PL

Pole magnetyczne Ziemi od dawna uznawane jest za wiarygodne źródło informacji dla ustalania orientacji przestrzennej, co powoduje, że kompas magnetyczny jest stosowany w nawigacji od stuleci i nadal posiadając wiele atrakcyjnych cech, nawet w erze technologii satelitarnych. Jednakże od momentu pojawienia się statków o stalowych kadłubach z napędem mechanicznym ich wykorzystanie stało się kłopotliwe. Obecnie dostępne są kompasy nazywane elektronicznymi, które funkcjonują w oparciu o pomiar pola magnetycznego, jednak zbudowane są odmiennie i posiadają odmienne właściwości. Celem tego opracowania jest przegląd technologii stosowanych do budowy sensorów stosowanych w tych kompasach, a także omówienie źródeł błędów i próby ich modelowania. W efekcie stwierdzono, że zasadniczym źródłem błędów pomiarów nadal jest charakter pola ziemskiego oraz wpływ pola magnetycznego nosiciela, jednak model błędów powinien uwzględniać również specyfikę miernika, w szczególności fakt, iż pomiar dokonywany jest poprzez rozłożenie wektora pola wypadkowego na składowe w osiach przestrzennego układu współrzędnych związanego z nosicielem, co skutkuje modyfikacją zależności znanych z teorii tradycyjnego kompasu magnetycznego.

EN

The Earth magnetic field is recognized as reliable source of information about the spatial orientation for a long time. For this reason the magnetic compass is used in the navigation from centuries and still possessing many attractive features, even in the era of satellite technologies. However from the moment when steel, machine-powered ships appeared their utilization became troublesome. At present so called electronic compasses are accessible and this picture seems be different. Indeed the new compass work basing on the measurement of the magnetic field, however them are constructed in a different manner and possess different proprieties. An aim of this elaboration is the review of technologies used for sensors applied in these compasses, and also the discussion of sources of errors, as well as attempts of their modelling. In the effect of considerations it remained that a main source of errors of measurement was still the character of the Earth field and the influence of the magnetic field of the vehicle. However the model of errors should take into account also the specificity of the new compass, particularly the fact, that measurement are made by the dissolution of the vector of the resultant field in axes of the spatial ship’s coordinate system. This is effective with the need of modification of the mathematical formulas well-known from the theory of the traditional magnetic compass.

3

Application of low-cost magnetic field and acceleration sensors in diagnostics of large-size structures

Szulim P., Mączak J., Rokicki K., Lubikowski K.

Diagnostyka

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2013

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Vol. 14, No. 4

43--49

EN

The paper presents the possibilities of using low-cost magnetic and acceleration sensors in diagnostic systems of large-scale structures made of ferromagnetic materials. It covers typical problems associated with their use as well as the review of commercially available low-cost solutions. A specially designed magnetic sensor equipped with a CAN interface, which allows for connecting a number of transmitters into a measuring network, were tested during the experiment.

PL

W pracy przedstawiono możliwość wykorzystania niskobudżetowych czujników pola magnetycznego i przyspieszeń w systemach diagnostyki konstrukcji wielkogabarytowych wykonanych z materiałów ferromagnetycznych. Przedstawiono typowe problemy występujące podczas ich użycia oraz dokonano przeglądu dostępnych na rynku tanich rozwiązań. W przeprowadzonym eksperymencie przetestowano specjalnie opracowane przetworniki pala magnetycznego wyposażone w interfejs CAN pozwalający nasączenie sieć pomiarową.

4

Zastosowanie niskobudżetowych czujników pola magnetycznego w diagnostyce konstrukcji wielkogabarytowych

Szulim P., Lubikowski K., Mączak J., Rokicki K.

Zeszyty Naukowe Instytutu Pojazdów / Politechnika Warszawska

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2012

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z. 3/89

143--154

PL

W pracy przedstawiono możliwość wykorzystania niskobudżetowych czujników pola magnetycznego i przyspieszeń w systemach diagnostyki konstrukcji wielkogabarytowych wykonanych z materiałów ferromagnetycznych. Przedstawiono typowe problemy występujące podczas ich użycia oraz dokonano przeglądu dostępnych na rynku tanich rozwiązań. W przeprowadzonym eksperymencie przetestowano specjalnie opracowane przetworniki pola magnetycznego wyposażone w interfejs CAN pozwalający na łączenie szeregu przetworników w sieć pomiarową.

EN

The paper presents the possibility of using low-cost magnetic and acceleration sensors for diagnostic systems of large-scale structures made of ferromagnetic materials. Typical problems that occur when they are used, and a review of commercially available low-cost solutions was shown. In the experiment was tested a specially designed magnetic sensor equipped with a CAN interface which allow to connect a number of transmitters in the network measurement.

5

Zakłócenia elektromagnetyczne w elektronicznych systemach alarmowych

Prauzner T.

Przegląd Elektrotechniczny

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2012

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R. 88, nr 12b

205-208

PL

W pracy przedstawione zostały podstawowe problemy związane z zakłóceniami o podłożu elektromagnetycznym, które w sposób istotny mają wpływ na parametry pracy podzespołów elektronicznych wchodzących w zakres budowy układów alarmowych. Poddano analizie zjawiska rozprzestrzeniania się zaburzeń elektromagnetycznych w otoczeniu systemów bezpieczeństwa, wywołujące zamierzone jak i stochastyczne nieprawidłowości mające wpływ na stabilną pracę systemu.

EN

In the paper were presented the fundamental issues of electromagnetic interference on the ground, which significantly affect the parameters of the electronic components within the scope of building alarm systems. We analyzed the phenomenon of propagation of electromagnetic disturbances in the environment of safety, causing intentional and stochastic irregularities affecting the stable operation of the system.

6

Design and fabrication of nanomagnetic sensors based on electrodeposited GMR materials

Nabiyouni G. R.

Metrology and Measurement Systems

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2009

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Vol. 16, nr 3

519-529

EN

The operation of magnetic sensors is based on different physical principles, leading to the fabrication of different magnetic sensor types. Commercially available magnetic sensors such as Hall effect devices, inductive coil and fluxgate magnetometers have their own advantages and limitations. Magnetoresistive sensors are based on the change of the electric resistivity when they are subjected to a magnetic field. We introduce a low-cost method i.e. electrodeposition of magnetic multilayers, in order to fabricate sensitive magnetic sensors. We have successfully grown Co/Cu and Ni/Cu multilayers on n-type (100) Si substrate, from a single electrochemical electrolyte containing either both (Co+2 and Cu+2) or both (Ni+2 and Cu+2) ions, for growing Co/Cu and Ni/Cu multilayers respectively. While a maximum change of 12 percent was observed in the electric resistivity of the Co/Cu films when they were subjected to a magnetic field of 2000 Oe, the maximum change in resistivity for Ni/Cu multilayers was only 3.5 percent. Nevertheless, the sensitivity of multilayer Ni/Cu films in low magnetic fields (up to 100 Oe) was found to be almost twice that obtained for Co/Cu films.

7

Testing of the three axis magnetometers for measurements of the earth's magnetic field

Szewczyk R., Salach J., Bieńkowski A.

Journal of Automation Mobile Robotics and Intelligent Systems

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2009

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Vol. 3, No. 4

96-98

EN

The paper presents experimental setup for testing of the three axis magnetoresisitive magnetometers for measurements of the magnetic field within the range of Earth's magnetic field. Measuring setup integrates three axis Helmholtz coils controlled by the specialized current source. The accuracy of magnetic field generated by the Helmholtz coils is up to 0.6% for the one direction. Presented experimental setup can be also applied for investigation and calibration of the other magnetometers utilizing magnetoresistive, Hall or fluxgate sensors.

8

High frequency magneto-impedance effect in glass-coated amorphous Co83.2 B3.3 Si5.9 Mn7.6 microwires

Lee H., Kim Y. S., Yu S. C.

Materials Science

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2003

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Vol. 21, No. 1

115-121

EN

The measurements of the giant magneto-impedance (GMI) were carried out in the amorphous Co83.2B3.3Si5.9Mn7.6 micro-wires at high frequency range from 100 MHz up to 1 GHz of an accurrent flowing along the wire and at varying axial dc-magnetic field in its range of š120 Oe. The wires, about 15žm in diameter, were fabricated by a glass-coated melt spinning technique. The shape of the impedance curves plotted vs. a dc-field is changing dramatically with the frequency. The phase angle was also strongly dependent on this field. The maximum value of GMI, around 250%, was reached at the frequency of about 500 MHz. The external dc-magnetic field changes the circumferential permeability as well as the penetration depth, both in turn change the impedance of the sample. The increments of GMI at high frequency can be understood in terms of the LC- resonance phenomena. The sudden change of the phase angle, as large as 180°, evidenced the occurrence of the resonance at a given intensity of the external dc-field.

9

Hollow ellipsoid of rotation as a physical model of tubular cylindrical ferromagnetic core

Nichoga V., Dub P., Kaczmarek Z.

Journal of Technical Physics

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2001

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Vol. 42, no 4

449--458

EN

Induction sensors with cores in the shape of hollow cylinder are widely used because of such advantages as decrease of mass and simplicity of manufacturing cores with defined geometry. Replacement of a real tubular cylindrical core by the model in the shape of hollow ellipsoid of rotation with equal values of relative lengths, ferromagnetic volumes and fluxes, that is proposed in the article, allows to find the calculation algorithms for determination of electromagnetic parameters of cylindrical rod with solid and tubular cores. The obtained algorithms take into account the influence of both the geometry and magnetic properties of core material on the electromagnetic parameters and are suitable for engineering calculations.