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Czesław Lewa (1937-2016)

Linde B. B. J.

Postępy Fizyki

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2016

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T. 67, z. 4

188

PL

Czesław Lewa urodził się w 1937 roku w Siporach, W roku 1961 ukończył studia w Wyższej Szkole Pedagogicznej w Gdańsku. Stopień doktora uzyskał w 1969 roku a doktora habilitowanego - w 1977 roku. W roku 1997 Czesław Lewa otrzymał tytuł profesora w zakresie fizyki. Od roku 1961 pracował w Katedrze Fizyki WSP w Gdańsku, która to uczelnia przekształciła się w 1970 roku w Uniwersytet Gdański. W latach 1985 i 1995 pracował również na Uniwersytecie w Rennes w Francji, gdzie w roku 1999 został wyróżniony doktoratem honorowym.

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Modal Analysis of a Trapezoidal Violin Built after the Description of Félix Savart

Duerinck T., Skrodzka E., Linde B.B.J.

Archives of Acoustics

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2014

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Vol. 39, No. 4

623--628

EN

One-dimensional experimental modal analysis of an unvarnished trapezoidal violin built after the description of F. Savart and an anonymous trapezoidal violin on display in the Music Instrument Museum of Brussels is described. The analysis has revealed ten prominent modes. A mode that may potentially play a role of the “tonal barometer” of the instrument is pointed out. The mode shapes are symmetric and of high amplitude, due to the construction of the instrument. Subjective evaluation of the sound quality demonstrated no pronounced difference between the trapezoidal violin and normal violin.

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Effect of Bass Bar Tension on Modal Parameters of a Violin’s Top Plate

Skrodzka E. B., Linde B.B.J., Krupa A.

Archives of Acoustics

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2014

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Vol. 39, No. 1

145--149

EN

Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1−).

4

Modal Parameters of Two Violins with Different Varnish Layers and Subjective Evaluation of Their Sound Quality

Skrodzka E. B., Linde B.B.J., Krupa A.

Archives of Acoustics

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2013

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Vol. 38, No. 1

75--81

EN

Two violins were investigated. The only intentionally introduced difference between them was the type of varnish. One of the instruments was covered with a spirit varnish, the other was oil varnished. Experimental modal analysis was done for unvarnished/varnished violins and a questionnaire inquiry on the instrument’s sound quality was performed. The aim of both examinations was to find differences and similarities between the two instruments in the objective (modal parameters) and subjective domain (subjective evaluation of sound quality). In the modal analysis, three strongly radiating signature modes were taken into account. Varnishing did not change the sequence of mode shapes. Modal frequencies A0 and B(1+) were not changed by oil varnishing compared to the unvarnished condition. For the oil varnished instrument, the frequency of mode B(1+) was lower than that of the same mode of the spirit varnished instrument. Our two violins were not excellent instruments, but before varnishing they were practically identical. However, after varnishing it appeared that the oil-varnished violin was better than the spirit-varnished instrument. Therefore, it can be assumed with a fairly high probability that also in general, the oil-varnished violins sound somewhat better than initially identical spirit-varnished ones.

5

Acoustical investigation of classical kneser liquids

Linde B. B. J., Lezhnev N. B.

Molecular and Quantum Acoustics

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2007

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Vol. 28

187-194

EN

In this paper the experimental values of acoustical parameters determined from ultrasonic spectroscopy for eleven Kneser liquids are presented. The experimental data give the possibility to calculate several values describing acoustical relaxation. From these results it was possible to conclude that in the relaxation process with one relaxation time all vibrational degrees of freedom take part.

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Relaksacja oscylacyjna w związkach halogenopodstawnych benzenu

Linde B.B.J., Lezhnev N.B.

Prace Naukowe Instytutu Telekomunikacji i Akustyki Politechniki Wrocławskiej. Konferencje

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2001

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Vol. 83, nr 27

413-418

EN

The acoustic investigations in the group of halogenated benzenes compounds and particularly research of the dependencies of acoustic parameters and the structure of the organic liquids, demonstrated some interesting regularities in the group of these compounds in gas and liquid states. In this paper the results of research in five cyclic liquids: bromo-, chloro-, fluoro- and jodobenzene were discussed in comparison to the benzene. The acoustic relaxation observed in all the compounds was found to result from Kneser's processes (vibrational relaxation). Based on investigations reported in this paper, as well as other, both experimental and literature data concerning a great number of compounds, one can draw a conclusion that almost all acoustic relaxation (Kneser-type) processes in liquids can be described using one relaxation time. It also seems that all vibrational degrees of freedom of the molecule take part in this process. It is known that arising of differences in transition probabilities could be caused by additional attraction in interaction of molecules having the dipole moments. A high value of dipole moments of halogenobenzenes with adequate benzene could be responsible for the difference of transition probabilities and changes of the relaxation times.