vibrational motion
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2021 ◽  
Vol 75 (12) ◽  
Author(s):  
Hans-Georg Weber

Abstract The theory of large extra compactified dimensions of space (ADD-model) predicts that gravity may become strong in a compactification space of the size of a molecule and may affect the vibrational motion of a molecule. In triatomic molecules like $$\hbox {NO}_{{2}}$$ NO 2 nuclear dynamics is strongly coupled to electronic dynamics at the intersection of electronic states (conical intersection). We discuss experimental results on $$\hbox {NO}_{{2}}$$ NO 2 which reveal that the collision-free molecule optically excited into a symmetric stretch vibration mode of an electronic state with conical intersection undergoes an irreversible non-radiative transition into an asymmetric stretch vibration mode in combination with a change of the electronic state. We suggest ascribing this irreversible non-radiative transition to a gravitational perturbation on the vibrational motion in $$\hbox {NO}_{{2}}$$ NO 2 . This gravitational perturbation deactivates the upper state of the optical transition. The width of the absorption line is given by the characteristic time of the gravitational perturbation and not by the radiative lifetime of the excited molecular state. Graphical abstract


Author(s):  
Ju Qiu ◽  
Jiali Tang ◽  
Chundu Sun ◽  
Fengyu Dai

Any aircraft in flight is subjected to dynamic loads. Following vibration-related accidents, a flow field and vibration analysis can be carried out to analyze the data and study the cause of the accident. When slit airflow enters the cavity between the tailplane structure and the elevator, a mixed vortex is formed. If the vortex-induced vibrational frequency of around 50 Hz happens to be close to the natural frequency of the structure at 46 Hz, it is likely to induce structural vibration (resonance). The resonance can cause excessive fatigue damage which can ultimately lead to structural failure and the loss of the component or the aircraft. Damping methods can be employed to control vibration within the structure by reducing the amplitude of that vibrational motion by 83%. This article details a recreation of one example of structural vibration within an airborne aircraft.


2021 ◽  
pp. 1-8
Author(s):  
Birthe Warnholtz ◽  
Merlin Schär ◽  
Pascale Cuny ◽  
Kathrin Sonntag ◽  
Dirk Beutner ◽  
...  

Introduction: The Vibrant Soundbridge (MED-EL Medical Electronics, Austria) is an active middle ear implant with a floating mass transducer (FMT) for patients with conductive, sensorineural, or mixed hearing loss. While the FMT is vertically aligned above the stapes head (SH) with the current Vibroplasty Clip coupler (MED-EL Medical Electronics), the new SH coupler was developed to mount the FMT on the inferior side of the stapes and to fit in the reduced middle ear space after canal-wall-down mastoidectomy. Methods: Using 11 human cadaveric temporal bones (TBs), placements of the new SH couplers on the stapes were examined, and effective stimuli to the cochlea were evaluated by measuring piston-like motion of the stapes footplate with a current of 1 mA on the FMT. The results were assessed in comparison with the Vibroplasty Clip coupler. Results: The new SH coupler showed perfect coupling on the stapes in 9 out of 11 TBs. A small gap between the SH and the plate of the connection link part was unavoidable in 2 TBs but had negligible effect on vibrational motion of the stapes. Vibrational motion of the stapes with the new SH coupler was reduced at frequencies above 3 kHz compared to the corresponding motion with the current Vibroplasty Clip coupler, but the relative attenuation over all 11 cadaveric temporal bones was <10 dB. Conclusions: The new SH coupler provides an alternative with more stable fixation when placement of the current Vibroplasty Clip coupler is limited due to insufficient space after canal-wall-down mastoidectomy, while still delivering effective stimuli to the cochlea.


2021 ◽  
Vol 6 ◽  
Author(s):  
Andreas Kainz ◽  
Roman Beigelbeck ◽  
Silvan Schmid

With their unparalleled mass sensitivity, enabling single-molecule mass spectrometry, nanomechanical resonators have the potential to considerably improve existing sensor technology. Vertical pillar resonators are a promising alternative to the existing lateral resonator designs. However, one major obstacle still stands in the way of their practical use: The efficient transduction (actuation &amp; detection) of the vibrational motion of such tiny structures, even more so when large arrays of such nanopillars need to be driven. While electrostatic forces are typically weak and, on the nanoscale even weaker when compared to a cantilever-like stiffness, it is worth revisiting the possibility of electrostatic actuation of nanomechanical pillars and other nanomechanical structures. In this paper, these forces produced by an external field are studied both analytically and numerically, and their dependencies on the geometric dimensions are discussed. Furthermore, the expected deflections for different configurations of pillar geometries are calculated and compared.


2021 ◽  
Author(s):  
Yu-Zhen Wang ◽  
Zhi-Xu Zhang ◽  
Chang-Yuan Su ◽  
Tie Zhang ◽  
Da-Wei Fu ◽  
...  

A hybrid perovskite material with dielectric phase transition obtained by the introduction of a moving group.


Author(s):  
Anna Maria Wernbacher ◽  
Leticia Gonzalez

Consideration of finite temperature and vibrational motion can be an essential component for accurate simulations of absorption spectra. Here we use finite-temperature Wigner phase-space sampling to investigate the intense absorption...


Author(s):  
Jochen Autschbach

The harmonic oscillator of chapter 2 is visited again, now in its quantum theoretical version. The solution of the Schrodinger equation (SE) is shown step-by step, as it features steps that are very similar to those used in solving the equations for the angular momentum and hydrogen-like orbitals in later chapters. The Morse oscillator has a potential function that is much more representative of the vibrations of atoms in molecules as the harmonic potential. The solutions of the harmonic and Morse oscillator are compared. It is then shown how nuclear vibrations in poly-atomic molecules are treated at the harmonic level. This requires the separation of internal degrees of freedom from the overall translation and rotation of a molecule, leading to the normal modes. The chapter also discusses basic aspects of vibrational spectroscopy and the selection rules of infrared and Raman vibrational spectroscopy.


2020 ◽  
Vol 19 ◽  
pp. 103465 ◽  
Author(s):  
M.A. Bek ◽  
T.S. Amer ◽  
Magdy A. Sirwah ◽  
Jan Awrejcewicz ◽  
Asmaa A. Arab

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