Radial Vibration Mode Research Articles

Influence of Single-Walled Carbon Nanotubes Enriched in Semiconducting and Metallic Tubes on the Vibrational and Photoluminescence Properties of Poly(para-phenylenevinylene)

A new synthesis method based on the electrochemical reduction of α,α,α′,α′-tetrabromo-p-xylene in the presence of single-walled carbon nanotubes (SWNTs) is used to obtain composites of carbon nanotubes (CNTs) functionalized with poly(para-phenylenevinylene) (PPV). To separate the effects of metallic and semiconducting CNTs on their interaction with PPV, the experiments are carried out with SWNTs enriched in semiconducting (S, 99%) and metallic (M, 98%) tubes. Significant changes in the relative intensity and shift of the radial breathing vibrational mode are reported in the Raman spectra of the as-prepared SWNTs samples, i.e., as mixtures of metallic (33%) and semiconducting (66%) entities and SWNTs enriched in M tubes (98%) that result from the electrofunctionalization with PPV. This different behavior originates in the noncovalent and covalent functionalization of SWNTs enriched in M and S SWNTs tubes with PPV, respectively. A gradual decrease in the absorption of the infrared (IR) bands of PPV situated...

A controllable circular ring acoustic focused field

Based on Huygens principle about the aspect of phased array, this paper presents a structure of cylindrical acoustic transducer consisting of circular ring piezoelectric transducer elements in radial vibration mode, which can be used to achieve the ultrasonic nondestructive test for the cylindrical scanning acoustic field in three-dimensional space. By analyzing the acoustic field of a single ring line source and a single element, the sound field distribution of the phased array is obtained for constructing circular ring acoustic focused field. By means of the phased array incentive mode, the phase difference of driving signals is generated and forms a regular time delay; with the accomplishment of sound field scanning in cylindrical three-dimensional space, the circular ring acoustic focused field can be controlled in real time.Theoretical analysis and finite element simulation results demonstrate that the size of the circular ring acoustic focused field can be controlled by the numbers of the excited array elements, which are 4, 8, 16 and 32 respectively in our work. We find that with more array element numbers, the circular ring acoustic field has better focused features. The radius size of the circular ring acoustic focused field can be controlled by the different locations of the focus positions which are 30 and 50 mm respectively in our work. And we find that as the distance between the focus positions and the center of piezoelectric wafer becomes longer, the radius of the circular ring acoustic focused field becomes bigger, and the position of the focus is equivalent to the radius of the circular ring acoustic focused field. The movement along the axial direction of circular ring acoustic focused field can be controlled by the angle of deflection, which are set as 0, 10 respectively in our work. And we find that the circular ring acoustic focused field is deflected in a corresponding deflection angle along the Z-axis, and the moving distance is FZ = F/sin . With the theoretical analysis and the experimental simulation, it can be shown that the structure of cylindrical acoustic transducer array presented in this paper could create an adjustable circular ring acoustic focused field and can potentially provide an acoustic field scan method in detection ultrasound, medical ultrasound and other areas of a cylindrical space.

High power density NaNbO3-LiTaO3 lead-free piezoelectric transformer in radial vibration modes

In the present work, the sintering temperature was able to substantially influence the microstructure and electrical properties of the lead-free ceramic 0.88NaNbO3–0.12LiTaO3. This composition without any acceptor doping presents a high mechanical quality factor, Qm, value of 1469 and a high Curie temperature of 305 °C by optimizing the sintering temperature at 1330 °C. We applied this material to make a device of disk-shaped piezoelectric transformers with a ring–dot structure and further focused on investigating the characteristics of the piezoelectric transformers. With matching load, a maximum efficiency of 92% occurs in the fundamental mode, and the maximum voltage gains are 5.5 and 3.7 for the fundamental and third radial vibration modes, respectively. The experimental results show a maximum output power of 10.5 W with a temperature rise of 27 °C. It is noteworthy that a high output power density (as high as 32.8 W cm−3) was obtained under a maximum input voltage of 180 V, which is comparable to the performance of PZT in a piezoelectric ceramic transformer device.

Resonance Raman spectroscopic study for radial vibrational modes in ultra‐thin walled TiO2 nanotubes

The study reports the observation of radial vibrational modes in ultra‐thin walled anatase TiO2 nanotube powders grown by rapid breakdown anodization technique using resonant Raman spectroscopic study. The as‐grown tubes in the anatase phase are around 2–5 nm in wall thickness, 15–18 nm in diameter and few microns in length. The Eg(ν1,ν5,ν6) phonon modes with molecular vibrations in the radial direction are predominant in the resonance Raman spectroscopy using 325 nm He–Cd excitation. Multi‐phonons including overtones and combinational modes of Eg(ν1,ν5,ν6) are abundantly observed. Fröhlich interaction owing to electron–phonon coupling in the resonance Raman spectroscopy of ultra‐thin wall nanotubes is responsible for the observation of radial vibrational modes. Finite size with large surface energy in these nanotubes energetically favor only one mode, B1g(ν4) with unidirectional molecular vibrations in the parallel configuration out of the three Raman modes with molecular vibration normal to the radial modes. Enhanced specific heat with increasing temperatures in these nanotubes as compared to that reported for nanoparticles of similar diameter may possibly be related to the presence of the prominent radial mode along with other energetic phonon mode. The findings elucidate the understanding of total energy landscape for TiO2 nanotubes. Copyright © 2015 John Wiley & Sons, Ltd.

Simulation of 1-3 Piezoelectric Composite Cylindrical Transducer

A cylindrical transducer consisting of 1-3 piezoelectric composite was designed. Several rectangular bar elements were arrayed and adhered on the cylindrical backing to become a tubular transducer. The elements were 1-3 piezoelectric ceramic/polymer composites. The lumped characteristic parameters of 1-3 piezoelectric composite were obtained according to Smith's model. Two type models of transducer were established and simulated by ANSYS. One model was same to the actual transducer element. The other was an approximate element of the piezoelectric tube by using the lumped characteristic parameters. The radial vibration mode of two type models was analyzed. The simulation results indicated that the frequency of transducer were respectively 8.9 kHz and 8.7 kHz under radial vibration mode. The relative deviation in two type models is less than 2%.

링형 압전 변환기의 면내 진동 특성

ABSTRACT This paper experimentally deals with the vibration characteristics of flat ring transducers used for ultrasonic sensors and actuators. Radial vibration mode, which is the fundamental mode of a thin piezoelectric transducer, was measured by a laser in-plane vibrometer. An impedance analyzer was used to measure natural frequencies. The results measured by experiments verified theoretical predictions. The vibration characteristics of ring transducers were identified according to the outer di-ameter size. The shape of the fundamental mode is almost uniform but slightly decreases from the inner to the outer circumferential surfaces. The natural frequency of the fundamental mode decreases as the outer diameter increases. It appears that the ring type transducer is suitable to excite uni-formly distributed vibration on a flat surface. * 1. 서 론 초음파 센서 또는 액추에이터에서 역학적 진동과 전기적 신호 간의 상호 변환에 압전 변환기 (transdu-cer)가 많이 사용된다 (1) . 변환기의 압전소자는 대개 원판형이다. 압전소자를 적층할 필요가 있을 때, 중심을 관통하는 볼트로 체결하므로 중앙이 비어있는 링형 압전 원판을 사용한다

Spectroelectrochemical properties of the poly[(2,5-bisoctyloxy)-1,4-phenylenevinylene]/single-walled carbon nanotube composite

Using surface-enhanced Raman scattering (SERS) and photoluminescence (PL) studies, new data concerning the electrochemical oxidation both of poly[(2,5-bisoctyloxy)-1,4-phenylene-vinylene] (BO-PPV) and the BO-PPV/HIPCO single-walled carbon nanotubes (SWNTs) composite are presented in this paper. The SERS studies performed at the excitation wavelengths of 752nm and 532nm of the BO-PPV/SWNTs composite that ensure the resonant excitation of the semiconductor and metallic nanotubes, respectively, reveal that the mixing of the two constituents results, on the one hand, in an isolation of semiconducting nanotubes from the bundles containing both metallic and semiconducting tubes and, on the other hand, in a functionalization of metallic SWNTs with BO-PPV. The isolation of semiconducting SWNTs is demonstrated by the narrowing of the G band and the change of the ratio between the intensities of the Raman lines situated in the low-frequency range that are assigned to the radial breathing vibrational modes. An additional isolation of the semiconducting nanotubes from the SWNTs bundles is reported when an electro-oxidation of the BO-PPV/SWNTs composite was performed in the potential range of (0; +2)V vs. Ag/AgCl. According to the Fourier transformed infra-red (FTIR) spectra and the SERS studies performed at an excitation wavelength of 1064nm, the chemical interaction of BO-PPV with HIPCO SWNTs reveals a charge transfer between the two constituents that leads to the formation of BO-PPV covalently functionalized SWNTs. The BO-PPV luminescence quenching effect induced by the presence of SWNTs that consists of a change in the relative intensities of the three PL bands of the polymer peaked at 1.73eV, 1.9eV and 2.07eV is due to the metallic tubes. The appearance of a new emission band at 2.32eV was regularly observed when electrochemical oxidation of the BO-PPV/SWNTs composite was performed in the potential range of (0; +2)V. The PL band at 2.32eV corresponds to ClO4− ions, which compensates the positive charges of BO-PPV generated during the electrochemical doping process.

Length dependence of the resonant magnetoelectric effect in Ni/Pb(Zr,Ti)O3/Ni long cylindrical composites

Magnetoelectric (ME) effect was studied in the long cylindrical Ni/Pb(Zr,Ti)O3/Ni layered composites prepared by electroless deposition. Three significant resonant peaks have been observed in the dependence of the ME voltage coefficient on the magnetic field frequency. The height of the composite cylinder has an important impact on the ME effect. With the height of the cylinder increase, the value of ME coefficient at static or low-frequency case increases, while the resonant frequencies decrease. Furthermore, the ME effect at the individual resonant frequencies can be weakened or enhanced due to the coupling of radial and axial vibration modes. The experimental values of resonant frequencies are in good agreement with the calculated ones. The results are useful for magnetoelectric devices with controllable multifrequency operation.

The Analysis of Piezoelectric Tube Stack for Radial Vibration Frequency

According to equivalent circuit principle, piezoelectric tube stack equivalent circuit is derived by the admittance of single piezoelectric thin tube, and the resonance frequency of piezoelectric tube stack for radial vibration is also calculated. The relationship between resonance frequency of radial vibration mode and average radius, thickness and height are obtained from analytical calculation. Analytical calculation and experiment results are compared, and they match well with each other.

Radial oscillations of neutral and charged hybrid stars

We construct stellar models of hadron stars and hybrid stars and calculate the frequencies of their lowest radial mode of vibration. Chandrasekhar's equation for radial oscillations is generalized for stars with internal electric fields and earlier versions of that generalization are simplified. For the hybrid stars a Gibbs construction is employed. It is found that the softening of the equation of state associated with the presence of deconfined quarks reduces the oscillation frequency. We show that a slight charge inbalance should lead to increased maximum mass, decreased central density and lower oscillation frequencies.

Omnidirectional lamb waves by axisymmetrically-configured magnetostrictive patch transducer

This work presents the generation of omnidirectional Lamb waves by a new magnetostrictive patch transducer (MPT) and investigates its generation mechanism. Although MPTs have been widely used for wave transduction in plates and pipes, no investigation reports the generation of omnidirectional Lamb waves in a plate by an MPT. For the generation, we propose an axisymmetrically-configured MPT that installs multiple axisymmetric turns of coil outside of a permanent cylindrical magnet located above the center of a circular magnetostrictive patch. After confirming the omnidirectivity of the proposed MPT experimentally, the mechanism of the Lamb wave generation and its frequency characteristics are investigated. It is also shown that the Lamb wave is most efficiently generated in a test plate when its wavelength is equal to two-thirds of the magnetostrictive patch diameter. If this wavelength¿patch diameter relation holds, the second radial extensional vibration mode of the patch of the proposed MPT is shown to be the mode responsible for generating the Lamb wave in a plate.

Research on Piezoelectric Tube Stack for Radial Vibration Mode

According to electro-mechanical equivalent principle, piezoelectric tube stack electro-mechanical equivalent circuit is derived by the admittance of single piezoelectric thin tube. The resonance frequency of piezoelectric tube stack for radial vibration mode is also calculated. The relationship between resonance frequencies and average radius, thickness and height with radial vibration mode are obtained through analytical calculation. And radial vibration mode is simulated by FEM .Analytical calculation and FEM simulation results are compared. They coincide well with each other.

Apparent effects of in-cylinder pressure oscillations and cycle-to-cycle variability on heat release rate and soot concentration under long ignition delay conditions in diesel engines

In diesel engines, long ignition delay due to cold in-cylinder conditions has been shown to lead to high cycle-to-cycle variability, as well as result in pressure oscillations due to rapid localised pressure rise rates from the resulting premixed combustion. These pressure oscillations appear as superimposed pressure waves on the engine indication graph, with an oscillation frequency corresponding to the first radial vibration mode. In the current study, the influences of pressure oscillations on heat release rate and the progress of in-cylinder soot concentration are investigated. Results showed that cycles where pressure oscillations occur reach a higher peak pressure than average or low pressure oscillation cycles, as a result of increased diffusion combustion rate and apparent mixing rate. Additionally, using in-cylinder soot pyrometry, cycles with high pressure oscillations were shown to exhibit increased soot oxidation rates. The combination of the two above-mentioned observed effects leads to the conclusion that pressure oscillations in direct injection diesel engines result in more rapid mixing due to increased turbulent intensity.

The Influence of Permeance Effect on the Magnetic Radial Forces of Permanent Magnet Synchronous Machines

An analytical model has been developed for analyzing the magnetic radial forces of permanent magnet (PM) machines. The air-gap magneto-motive force harmonics, stator slotting effect, and rotor saliency effect are considered in the model. Extensive simulations at no-load and under load conditions are performed for analyzing the radial force and vibration modes of different PM machines with different winding and rotor topologies. Concentrated winding with ${\rm q}=0.4$ , conventional concentrated winding with ${\rm q}=0.5$ , and the distributed winding with ${\rm q}=2$ are studied taking into account also two rotor types (IPM and SPM rotor). The obtained results show that for all machine types the rotor saliency has a considerable effect on the air-gap flux density and radial force characteristics. For the SPM rotor type, the radial force modes are constant with the time, however for the IPM rotor type the rotor saliency effect induce additional time harmonics in the radial force modes (including mode zero).

Investigation on the Frequencies of Radial Breathing Mode and Radial Breathing-Like Mode of Carbon Nanotubes

Carbon nanotubes (CNTs), one of the important symbol to enter the era of nanotechnology, becomes the most attractive materials with the unique properties, and CNTs shows extensive potential application in drug molecular transmission, CNTs tip and CNTs-based sensors. However, the application of nano-device requires more accurate research about geometric, electronic and mechanical properties which matches to radial breathing vibrational mode in Raman spectroscopy experiment. The shapes and frequencies of radial breathing mode(RBM) and radial breathing-like mode(RBM-like) were investigated by the modified beam element model based on molecular mechanics, and the relationship of frequencies of zigzag and armchair CNTs with length - diameter aspect ratio, diameter and chirality were also discussed respectively. The results show that there are RBM and RBM-like in radial vibration of CNTs, and their frequencies are approximate.

Analysis of vibrational behaviors of microtubules embedded within elastic medium by Pasternak model

Microtubules in living cells are very important component for various cellular functions as well as to maintain the cell shape. Mechanical properties of microtubules play a vital role in their functions and structure. To understand the mechanical properties of microtubules in living cells, we developed an orthotropic-Pasternak model and investigated the vibrational behavior when microtubules are embedded in surrounding elastic medium. We considered microtubules as orthotropic elastic shell and its surrounding elastic matrix as Pasternak foundation. We found that due to mechanical coupling of microtubules with elastic medium, the flexural vibration is increased with the stiffening of elastic medium. We noticed that foundation modulus (H) and shear modulus (G) have more effect on radial vibrational mode as compared to longitudinal vibrational mode and torsional vibrational mode.

Performance analysis for acoustic well logging receivers

The structure of acoustic logging receivers can change their performance directly. In this article, impedance characteristics and receiving sensitivities of three kinds of acoustic logging receivers were numerically analyzed with the finite element method. The modeling results showed that: The piezoelectric tube transducer in radial vibration mode had higher receiving sensitivity in the frequency range of 8-20 kHz with some ups and downs, while its sensitivity changed great below 5 kHz. The laminated circles transducer in bending vibration mode had higher sensitivity and better flatness below 4 kHz, but its sensitivity and flatness changed lower from 8 kHz to 20 kHz. The rectangular laminated piezoelectric transducer in the length stretching mode had better flatness below 20 kHz. In addition, acoustic well logging receivers in the future will have higher sensitivity, wider frequency bandwidth and smaller volume, which was pointed out in the article.

Observation of phonon hopping in radial vibrational modes of trapped ions

We observed phonon hopping by using the radial vibrational motion of trapped ions and we investigated the properties of radial mode phonons, which can be used for quantum simulation of the Hubbard model. This study represents an essential step toward realizing a physical implementation of the Bose-Hubbard model with trapped ions.

Coupled oscillations of a protein microtubule immersed in cytoplasm: an orthotropic elastic shell modeling.

Revealing vibration characteristics of sub-cellular structural components such as membranes and microtubules has a principal role in obtaining a deeper understanding of their biological functions. Nevertheless, limitations and challenges in biological experiments at this scale necessitates the use of mathematical and computational models as an alternative solution. As one of the three major cytoskeletal filaments, microtubules are highly anisotropic structures built from tubulin heterodimers. They are hollow cylindrical shells with a ∼ 25nm outer diameter and are tens of microns long. In this study, a mechanical model including the effects of the viscous cytosol and surrounding filaments is developed for predicting the coupled oscillations of a single microtubule immersed in cytoplasm. The first-order shear deformation shell theory for orthotropic materials is used to model the microtubule, whereas the motion of the cytosol is analyzed by considering the Stokes flow. The viscous cytosol and the microtubule are coupled through the continuity condition across the microtubule-cytosol interface. The stress and velocity fields in the cytosol induced by vibrating microtubule are analytically determined. Finally, the influences of the dynamic viscosity of the cytosol, filament network elasticity, microtubule shear modulus, and circumferential wave-number on longitudinal, radial, and torsional modes of microtubule vibration are elucidated.

Noniterative method for evaluation of the complex material constants of piezoelectric ceramics in the radial vibration mode

Abstract A new noniterative method, for determining the dielectric, piezoelectric and elastic constants, in complex form, for piezoceramic materials, in the radial mode, was proposed. This method uses the standard procedure to determine the elastic compliance and Poisson factor and the measurement of admittance at two frequencies to calculate the dielectric and piezoelectric constants, by solving a system of two equations. The accuracy of the new method was determined for materials with different planar coupling coefficients ( k p = 2.5–57%) and mechanical quality factors ( Q m = 20–3000). This method proved to be very accurate for all materials especially for those with large coupling factors. The accuracy of standard method was also evaluated for the same materials.