Separation of piano keyboard vibrations into tonal and broadband components

A new method is presented for splitting musical notes into tonal and broadband components by removing the harmonic peaks from the spectra. This method was used to analyse the key vibrations of eight pianos (four grand and four upright). The broadband component of vibrations was found to be more intense in the upright pianos than in the grand pianos, while no such difference was found in the tonal component. As grands are considered to be superior to uprights, this suggests that it may be possible to improve upright pianos by reducing the strength of the broadband component of vibrations.     

Mural inspection by vibration measurements with TV-holography

A commonly encountered problem in the conservation of historical murals is the identification of sections in the plaster that have detached from the wall and thus threaten to fall off. Commonly, walls are inspected by the acoustic response to a gentle finger-tapping (percussion method). Since this is a costly and cumbersome technique, means for a more automatic inspection are searched for. A TV-holography system of increased sensitivity in combination with acoustic excitation of the object is shown to be a new and powerful tool for monitoring of loose areas. It has the advantage of non-contact and remote operation which, for example, is extremely useful in large buildings. Principles of the method, experimental results obtained at an artificial wall in the laboratory, and a thorough comparison of results from historical sites gained by the traditional percussion method and the new technique are presented. The latter shows very good agreement in the assessment of wall quality and thus is evidence of the suitability of the optical equipment for tasks in conservation.     

Vibration and instability analysis of tubular nano- and micro-beams conveying fluid using nonlocal elastic theory

A nonlocal Euler–Bernoulli elastic beam model is developed for the vibration and instability of tubular micro- and nano-beams conveying fluid using the theory of nonlocal elasticity. Based on the Newtonian method, the equation of motion is derived, in which the effect of small length scale is incorporated. With this nonlocal beam model, the natural frequencies and critical flow velocities for the case of simply supported system and for the case of cantilevered system are obtained. The effect of small length scale (i.e., the nonlocal parameter) on the properties of vibrations is discussed. It is demonstrated that the natural frequencies are generally decreased with increasing values of nonlocal parameter, both for the supported and cantilevered systems. More significantly, the effect of small length scale on the critical flow velocities is visible for fluid-conveying beams with nano-scale length; however, this effect may be neglected for micro-beams conveying fluid.     

A reduced dimensionality model of torsional vibrations in star molecules

The torsional vibrations of star molecules are studied with a reduced dimensionality model. In this model, the molecule is described by two equivalent sets of lumped inertial cylinders and vibrational frequencies are predicted by solution of the coupled equations of motion. Force constants are determined by including them as free parameters in the model and fitting the computed frequencies to their analogs as determined using full normal coordinate analysis at the HFSCF level of theory. Best agreement between the methods occurs when torsional force constants are included for the first two layers of the molecule. This reveals that non-bonded torsional interactions are important in the vibrational dynamics of these systems. Further insight is afforded by an analysis of why simple harmonic oscillator models are sufficient for modeling some related systems but fail to reproduce the trend in global mode frequencies for saturated aliphatic star molecules. The analysis reveals that the origin of this failure lies in backbone flexibility in these branched polymeric systems.     

Measurement of transverse vibrations/visualization of mode shapes in square plate by using digital speckle pattern interferometry and wavelet transform

New filtering scheme is investigated and implemented on digital speckle pattern interferometric fringes to enhance the signal-to-noise ratio (SNR) in the speckle interferograms. To establish the potential of new filtering scheme the experiment was conducted on the vibrating cantilever beam. Experimental results revealed that the new filtering scheme is more powerful than other known filtering schemes (Kumar et al. Opt Laser Eng 2004;41:81–93. Kumar et al. Opt Laser Technol 2001;33:567–571. Shakher et al. Opt Eng 2002;41:176–180. Shakher et al. Proceedings ICICS, Singapore, 9–12 September 1997, p. 953–956. Bowler et al. Proceedings of IEE second international conference on image processing, London, 1986, p. 24–26. Lim. Opt Eng 1981;20:670–678. Devila et al. J Mod Opt 1995;42:1795–1804; Kaufmann et al. Opt Eng 1996;35:9–14). The new scheme reduced the speckle noise and improved SNR in speckle interferograms. Further, the new investigated filtering scheme is implemented to study the mode shapes of square plates under two different boundary conditions. In the first condition all the edges of the square plate were fixed while in the second condition two adjacent edges were fixed and the remaining two edges were free. From the experimental results it is clear that the mode shapes are more distinctly visible with the implementation of the new filtering scheme as compared to other known schemes. Under both the boundary conditions the recorded resonance frequencies were compared with the calculated values of resonance frequencies based on classical theory. The results obtained form DSPI show good agreement with classical theory.     

Thickness-shear vibration of a quartz plate connected to piezoelectric plates and electric field sensing

We study thickness-shear vibration of a quartz plate connected to two piezoelectric ceramic plates with initial deformations caused by a biasing electric field. The theory for small deformations superposed on finite biasing deformations in an electroelastic body is used. It is shown that the resonant frequencies of the incremental thickness-shear vibration of the quartz plate vary with the biasing electric field. The biasing electric field induced frequency shift depends linearly on the field. Therefore this effect may be used for electric field sensing. The dependence of the electric field induced frequency shift on various material and geometric parameters is examined. When the electric field is of the order of 100 V/mm, the relative frequency shift is of the order of 10⁻⁵. The case when the piezoelectric plates are replaced by piezomagnetic plates is also investigated for magnetic field sensing, and similar results are obtained.     

Novel Optical Vibration Sensor Using External Cavity Feedback: Novel Optical Vibration Sensor Using External Cavity Feedback

A novel low cost, non-contact optical vibration sensor requiring only a single optoelectronic component has been developed. It consists of a continuous wave semiconductor laser operating with external optical feedback. Vibrations have been measured at frequencies of up to 600 Hz with target reflectivities lower than 5%. When calibrated, the sensor demonstrates satisfactory output for submicron vibration amplitudes. Accuracies of 0.2% have been obtained over a range of 1 mm.     

低噪音摩阻复台材料影响因素的探讨

采用动态粘弹谱仪（ＤＤＶ）、电子扫描显微镜（ＳＥＭ）和摩擦试验机等对影响摩阻复合材料制动噪音的因素进行了探讨。结果表明，摩阻材料基体的合理改性以提高其损耗角正切ｔａｎδ对减少振动、降低噪音行之有效。同时对传统解决噪音的方法，如添加固体润滑剂、橡胶共混等进行了分析比较。     

Preparation of some silyl esters and study of their vibration spectra in gas and condensed phases

A new preparative route for silyl esters is described, involving reaction of silyl bromide and trisalkyltin esters. The far infrared spectrum of some simple esters are reported; an investigation of the shifts in the carbonyl stretching band on condensation shows no significant differences in behaviour between methyl and silyl esters.

---

Darstellung einiger Silylester und Untersuchung der Vibrationsspektren in der Gasphase und in kondensierter Phase

Zusammenfassung Es wird ein neuer präparativer Weg (über Silylbromid und Trisalkylzinnester) für die Synthese von Silylestern beschrieben. Das ferne IR einiger Ester wird angeführt; eine Untersuchung der Verschiebung der Carbonyl-Streck-Frequenz bei Kondensation zeigt keine signifikanten Unterschiede zwischen Methyl- und Silyl-Estern.