Contents of issue 4, vol. 30 (2005)

  1. W. Bochniak, J. Cieślik, Uncertainty in vibration energy flow analysis, Archives of Acoustics, 30, 4, 451-463
  2. Z. Ranachowski, A. Bejger, Fault diagnostics of the fuel injection system of a medium power maritime diesel engine with application of acoustic signal, Archives of Acoustics, 30, 4, 465-472
  3. J. Iwaniec, Uncertainty in structure dynamics resulting from matrix ill-conditioning, Archives of Acoustics, 30, 4, 473-482
  4. M. Iwaniec, The influence of constructional parameters on stiffened plates sound radiation, Archives of Acoustics, 30, 4, 483-494
  5. Z. Damijan, Changes of selected biochemical parameters of blood, densytometric and strength bones of rats under low frequency vibration, Archives of Acoustics, 30, 4, 495-505
  6. Z. Klimonda, M. Lewandowski, A. Nowicki, I. Trots, P.A. Lewin, Direct and post-compressed sound fields for different coded excitations - experimental results, Archives of Acoustics, 30, 4, 507-514
  7. E. Danicki, Spectral theory of unidirectional transducers, Archives of Acoustics, 30, 4, 515-519
  8. A. Snakowska, Appearance of the acoustic and electromagnetic lateral wave in propagation phenomena, Archives of Acoustics, 30, 4, 521-532
  9. R. Panuszka, J. Wiciak, M. Iwaniec, Experimental assessment of coupling loss factors of thin rectangular plates, Archives of Acoustics, 30, 4, 533-551
  10. Chronicle, 5th EAA International Symposium on Hydroacoustics, Archives of Acoustics, 30, 4, 553-565
W. Bochniak, J. Cieślik, Uncertainty in vibration energy flow analysis
AGH University of Science and Technology
Department of Robotics and Machine Dynamics
Al. Mickiewicza 30, 30-059 Kraków, Poland
e-mail: bochniak@agh.edu.pl, cieslik@agh.edu.pl
(received April 30, 2005; accepted October 23, 2005)
Introducing uncertainty considerations into simulation will facilitate exactitude assessment and help to boost the designer's confidence in simulation. The sources of uncertainty marked as the sensitivity parameters have an impact on the vibrational energy flow simulation and must be factored into the solution process. One of these parameters, the excitation frequency, has been identified and analyzed. The techniques for quantifying the effects of uncertainties are presented. The transmission of vibrational energy flow in plates is analyzed by the structural intensity method. A typical case for vehicle structures has been selected as an example: a simply supported plate under tangential force excitation. The relations between the structural intensity distribution and structural mode shapes and the effects of excitation frequency on the changes of energy flow in plate are discussed. Finally, the potential application of the structural intensity technique towards for the design of vehicle structures is discussed.
Key words: vibration energy, structural intensity, uncertainty of energy distribution.


Z. Ranachowski*, A. Bejger**, Fault diagnostics of the fuel injection system of a medium power maritime diesel engine with application of acoustic signal
*Institute of Fundamental Technological Research
Polish Academy of Sciences
Świętokrzyska 21, 00-049 Warszawa, Poland
e-mail: zranach@ippt.gov.pl
**Maritime University of Szczecin
Podgórna 51, 70-205 Szczecin, Poland
e-mail: abejger@am.szczecin.pl
(received May 19, 2005; accepted September 2, 2005)
The possibilities of application of a portable system for registration of the acoustic signal in the frequency range of 1000-10000 Hz for diagnosing common faults of the fuel injection system of the maritime diesel engine are presented. Clear differences in the registered waveforms are occurring when the records of the working fuel injector are compared with the other ones recorded in the injector with blocked nozzle orifice and when insufficient amount of fuel is delivered. Signal signatures of the operating fuel pump at three operating conditions are also presented. A procedure of comparing the acoustic signals registered on the stub of similar faulty and good engine elements is recommended by the authors as efficient and easy for application.
Key words: Diesel engine fault diagnostics, vibration analysis, marine accidents.


J. Iwaniec, Uncertainty in structure dynamics resulting from matrix ill-conditioning
AGH University of Science and Technology
Department of Robotics and Machine Dynamics
Al. Mickiewicza 30, 30-059 Kraków, Poland
e-mail: asical@poczta.onet.pl
(received April 30, 2005; accepted October 23, 2005)
In the paper there are discussed certain issues concerning ill-posed problems that frequently appear in inverse problems, modal analysis, acoustics and other methods making use of matrix algebra. There is presented the mathematical definition, application of the singular value decomposition method to ill-posed problems detecting as well as a new method of improving such problems conditioning by the use of the Tikhonov regularization method. In the paper are presented some results of solution estimation of the Fredholm integral equation of the first kind that is the classical ill-posed problem. Analysis was carried out in the Matlab environment by means of the least squares and Tikhonov regularization methods for both the noiseless and noisy cases.
Key words: ill-posed problem, ill-conditioned matrix, Tikhonov regularization method.


M. Iwaniec, The influence of constructional parameters on stiffened plates sound radiation
AGH University of Science and Technology,
Faculty of Mechanical Engineering and Robotics,
Structural Acoustics and Smart Materials Group
Al. Mickiewicza 30, 30-059 Kraków, Poland
e-mail: iwaniec@uci.agh.edu.pl
(received April 30, 2005; accepted October 23, 2005)
This work concerns the method of the plate parameter selection and the choice of the stiffening set, assuming the minimization or maximization of the energy stored or radiated by a stiffened plate as a criterion. The energy balance equations based on the SEA method were used in order to quickly evaluate the energy flow as a function of chosen constructional parameters. Calculations of mechano-acoustic energy flow were performed in AutoSEA and Matlab environment.
Key words: stiffened plate, energy balance, SEA method, sound power.


Z. Damijan, Changes of selected biochemical parameters of blood, densytometric and strength bones of rats under low frequency vibration
AGH University of Science and Technology,
Faculty of Mechanical Engineering and Robotics
Al. Mickiewicza 30, 30-059 Kraków, Poland
e-mail: damijan@imir.agh.edu.pl
(received April 30, 2005; accepted October 23, 2005)
The aim of the research is to analyze the changes of selected biochemical blood, densitometric parameters and bone strength of rats under exposure to low-frequency vibrations. Experiments were run on 30 Wistar rats randomly divided into three groups: the first group was first exposed to vibrations when rats were 20 days old: _20 - before puberty, the second group was subjected to vibrations from the 70-th day on: _70 - after reaching puberty, the third is the control group: _K. On the 145-th day the rats' _20 and _70 bones were subjected to biochemical examination, followed by densitometric and bone strength tests.
Key words: low-frequency vibrations, biochemical blood, densitometric parameters, bone strength tests.


Z. Klimonda*, M. Lewandowski*, A. Nowicki*, I. Trots*, P.A. Lewin**, Direct and post-compressed sound fields for different coded excitations - experimental results
*Institute of Fundamental Technological Research
Polish Academy of Sciences
Świętokrzyska 21, 00-049 Warszawa, Poland
**Drexel University, Philadelphia, PA (received January 10, 2005; accepted May 31, 2005)
Coded ultrasonography is intensively studied in many laboratories due to its remarkable properties: increased depth penetration, signal-to-noise ratio (SNR) gain and improved axial resolution. However, no data concerning the spatial behavior of the pressure field generated by coded bursts transmissions were reported so far. Five different excitation schemes were investigated. Flat, circular transducer with 15 mm diameter, 2 MHz center frequency and 50\% bandwidth was used. The experimental data was recorded using the PVDF membrane hydrophone and collected with computerized scanning system developed in our laboratory. The results of measured pressure fields before and after compression were then compared to those recorded using standard ultrasonographic short-pulse excitation. The increase in the SNR of the decoded pressure fields is observed. The modification of the spatial pressure field distribution, especially in the intensity and shape of the sidelobes is apparent. Coded sequences are relatively long and, intuitively, the beam shape could be expected to be very similar to the sound field of long-period sine burst. This is true for non-compressed distributions of examined signals. However, as will be shown, the compressed sound fields, especially for the measured binary sequences, are similar rather to field distributions of short, wideband bursts.
Key words: coded excitation, ultrasonic field distribution, pulse compression, matched filtration, medical imaging.


E. Danicki, Spectral theory of unidirectional transducers
Institute of Fundamental Technological Research
Polish Academy of Sciences
Świętokrzyska 21, 00-049 Warszawa, Poland
e-mail: edanicki@ippt.gov.pl (received January 5, 2005; accepted June 20, 2005)
A spectral theory of single-phase unidirectional transducers of the surface acoustic waves is presented. It helps to evaluate the stop-band width where the directionality takes place, and allows one to optimize the transducer structure in order to obtain its symmetric frequency response, with maximum directionality at the stop-band center.
Key words: surface acoustic waves, interdigital transducers.


A. Snakowska, Appearance of the acoustic and electromagnetic lateral wave in propagation phenomena
University of Rzeszów, Institute of Physics
Rejtana 16a, 35-310 Rzeszów, Poland
e-mail: asnak@univ.rzeszow.pl
(received April 30, 2005; accepted October 23, 2005)
The paper presents the appearance of lateral waves of the acoustic and electromagnetic type in various physical phenomena, from the earthquakes up to ultra-high frequency radio-wave propagation in stratified medium. The lateral wave appears in the process of wave refraction to the medium characterized by higher wave speed, if the angle of incidence exceeds the critical value. The lateral wave arrives at the receiver first and in some cases is the only remaining wave at long distances, thus it plays an important role in early warning, wireless communication in lossy environments or ground penetrating radar applications, when geometric optic model leads to significant errors.
Key words: acoustic, electromagnetic lateral wave, two media interface, multilayered media.


R. Panuszka, J. Wiciak, M. Iwaniec, Experimental assessment of coupling loss factors of thin rectangular plates
AGH University of Science and Technology
Laboratory of Structural Acoustics and Intelligent Materials
Al. Mickiewicza 30, 30-059 Kraków, Poland
(received March 9, 2005; accepted September 2, 2005)
Knowledge of Coupling Loss Factors (CLF's) for energy flow evaluation in structural elements of complex mechanical systems is fundamental. Several experiments were conducted to evaluate CLFs of different perpendicular connections of rectangular plates. The method of energy storage was conducted under acoustic free-field conditions, and a large number of thin plates with different designs of junctions were examined. The tests included two types of connections: welded line junction and point junctions. In the first type of connection, the influence of the thickness ratio of plates on CLFs values was tested. In the second type of connection the influence of the point of distribution at junctions on CLFs values were tested. Other tests were done to establish the impact of junction design on CLFs. Welded line junctions have a tendency to decrease the CLFs when the ratio of thickness of plates is increased. The CLFs also increase with density of joining points. Maximal values of CLFs were observed for spot-welded junctions. Mid-values were represented by screw-bolted joints and the lowest values by riveted junctions.
Key words: statistical energy analysis, coupling loss factor, rectangular plates connections, welded junction, point junction, acoustic power flow.


Chronicle, 5th EAA International Symposium on Hydroacoustics
Puck, May 16-19, 2005, Poland
5th EAA International Symposium on Hydroacoustics
The 5th EAA International Symposium on Hydroacoustics together with domestic XXII Symposium on Hydroacoustics took place in Puck at the Sport and Training Centre DELFIN, May 16-19, 2005.
The 5th EAA International Symposium on Hydroacoustics was organized by Naval Academy in Gdynia, Gdańsk University of Technology, European Acoustic Association, Polish Acoustical Society (Gdańsk Division) and Ultrasonic Division of the Committee on Acoustics of the Polish Academy of Sciences. Prof. Grażyna Grelowska, the vice-rector of Naval Academy in Gdynia, was the chairman of the Organizing Committee.
There were professors from famous European universities in the Scientific Committee. The professors arrived from, among others, Germany, Denmark, Russia, France, Italy, Greece, Turkey and Poland. The chairman of Scientific Committee was Prof. Eugeniusz Kozaczka who is the president of Polish Acoustical Society and who represents Poland in European Acoustics Association.
The main aim of the symposium is giving opportunity to exchanging experiences and information among research centres dealing with underwater acoustics and ultrasound.
The Symposium subject included:
  • sound propagation in the sea,
  • ambient and ship noise,
  • nonlinear acoustics,
  • ultrasonic transducers,
  • signal and data processing,
  • sonar systems,
  • other topics related to underwater acoustics.
  • 70 scientists have registered to the Symposium representing research centres mainly from Poland but also from other European countries and Canada.
    30 papers were presented, including 3 following invited papers:
  • E. Kozaczka - Modern applications of maritime technology.
  • A. Bobrowicz - Obrona bierna okrętów Marynarki wojennej RP.
  • I. Didenkulov, S. Muyakshin, D. Selivanovsky - Rotation of small particles in sound field and possible mechanism of sound perception.
  • All accepted papers were published in the periodical "Hydroacoustics". vol. 8.