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1

Identification of failure transformers 22/0,4 KV and 110/23 KV using SFRA method

Brandt M., Michalík J.

TTS Technika Transportu Szynowego

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2013

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R. 20, nr 10

3505--3512

EN

The article deals with the identification type of faults in power transformer using the method SFRA. The results taken from this transformer are compared with the results taken from experimental distribution transformer.

2

Educational Implementation of a Sound Level Meter in the LabVIEW Environment

Barański R., Wszołek G.

Archives of Acoustics

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2013

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Vol. 38, No. 1

19--26

EN

As a consequence of recent implementations of EU Directives related to noise protection more and more students of various AGH-UST programs are introduced to the basics of acoustic measurements. Students at various levels of theoretical background in the field of acoustic measurements are offered practical training in measurements using digital sound analyzers. The situation would be optimal if each student could have a device at his/her own disposal. Unfortunately, such a situation is not possible at the moment because of various reasons. With the above problem in mind, a dedicated software package has been developed, implemented in the LabVIEW environment, which allows detailed studies of problems related to the acoustic signal measurement using sound level meters, as well as tasks in spectral analysis (1/1 and 1/3 band filters) and narrow-band (FFT) analysis. With such organization during the introductory laboratory classes each student is offered a direct individual contact with a virtual device that is properly pre-programmed for realization of a well-constructed learning process. It definitely facilitates understanding of the essence of acoustic signal measurements and provides a good basis for further laboratory work carried out as a team-activity.

3

Właściwości obwodów typu π1 do rezonansowych wzmacniaczy mocy dla różnych wartości dobroci wypadkowej

Modzelewski J.

Elektronika : konstrukcje, technologie, zastosowania

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2010

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Vol. 51, nr 2

17-23

PL

W artykule przeanalizowano wpływ dobroci wypadkowej na charakterystyki częstotliwościowe impedancji wejściowej i transimpedancji obwodów rezonansowego typu π1 o różnych wartościach przekładni rezystancyjnej. Wyznaczono przebieg charakterystyk częstotliwościowych unormowanej impedancji wejściowej i transimpedancji tego obwodu w otoczeniu częstotliwości rezonansowej dla kilku typowych wartości dobroci wypadkowej i przekładni. Dla obwodów π1 o różnych wartościach przekładni obliczono także zależność współczynników tłumienia drugiej i trzeciej harmonicznej prądu wejściowego od dobroci wypadkowej. Przedstawione charakterystyki pozwalają uprościć projektowanie obwodów Vπ1 do rezonansowych wzmacniaczy mocy klasy AB, klasy B i klasy C.

EN

In the paper an influence of the loaded quality factor on frequency response of input impedance and transimpedance of the π1 resonant circuits with different values of resistance-transformation ratio is analyzed. Normalized input impedance and transimpedance frequency responses in the neighbourhood of the resonant frequency for a few typical values of the loaded quality factor and resistance-transformation ratio are calculated. Attenuation coefficients of the second and third harmonic of the input current versus the loaded quality factor are also determined for the π1 circuits with different values of the resistance transformation ratio. Presented characteristics allow to simplify the design of the π1 circuits for class AB, class B and class C tuned power amplifiers.

4

Time-frequency responses of parallel connection of parametric sections

Piwowar A., Walczak J.

Prace Naukowe Politechniki Śląskiej. Elektryka

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2009

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z. 2

65-69

EN

In this paper the method for determining the frequency responses of parallel connection of parametric sections when assuming that the impulse-responses of elementary sections are known is presented. The results obtained are illustrated by an example.

PL

W artykule opisano metodę wyznaczania charakterystyk częstotliwościowych połączeń równoległych sekcji parametrycznych LTV, przy założeniu że znane są impulsowe funkcje przejścia sekcji elementarnych. Uzyskane wyniki zilustrowano przykładem.

5

Selected Factors Affecting Uncertainty of All-Weather Microphones Research

Wszołek G.

Archives of Acoustics

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2009

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Vol. 34, No. 4

547-557

EN

Testing of devices for acoustic measurements in a free-field are being performed at the stage of designing and type certification. Free-field tests are performed only in a few laboratories – mainly in National Metrology Institutes. These are: Danish Primary Laboratory of Acoustics (DPLA, Denmark), Physikalisch Technische Bundesanstalt in Braunschweig (PTB, Germany), National Physical Laboratory (NPL, United Kingdom) National Institute of Standards and Technology (NIST, United States of America). The Vibroacoustic Laboratory of the Department of Mechanics and Vibroacoustics, AGH is the only place in Poland where this type of tests is performed. This is calibration laboratory, which has an accreditation of Polish Centre for Accreditation (AP 022). Certain factors related to the determination of frequency and directivity responses of all-weather microphones, which have a significant influence on the uncertainty of the obtained results – are presented in the paper. The response values, given below, indicate the calibration accuracy. This accuracy is necessary since the aim of the measurements is to determine corrections and designing of the proper compensating filters, which will allow to eliminate any influence of devices on the acoustic field, the parameters of which are actually under testing. This is directly related to the uncertainty assessment of environmental measurements (e.g. to the accuracy of acoustic maps). The necessity of collaboration of laboratories performing such tests and the need of inter-laboratory comparisons is pointed out in the present paper. The unification of the method of testing and the assessment of the uncertainty of results seems to be necessary.

6

Frequency responses of linear interval plants with delay

Busłowicz M.

Control and Cybernetics

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1999

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Vol. 28, no 2

281-289

EN

The paper gives a simple new method for computing envelopes of the magnitude and phase plots of the family of linear time-invariant interval plants with uncertain delay. The undelayed part of the plant is described by the family of interval transfer functions (the nominator and denominator polynomials are interval polynomials). The proposed method requires the knowledge of the Kharitonov polynomials associated with the nominator and denominator polynomials.