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Sample records for vibrational frequencies intensities

  1. Prototype fiber Bragg Grattings (FBG) sensor based on intensity modulation of the laser diode low frequency vibrations measurement

    Science.gov (United States)

    Setiono, Andi; Ula, Rini Khamimatul; Hanto, Dwi; Widiyatmoko, Bambang; Purnamaningsih, Retno Wigajatri

    2016-02-01

    In general, Fiber Bragg Grating (FBG) sensor works based on observation of spectral response characteristic to detect the desired parameter. In this research, we studied intensity response characteristic of FBG to detect the dynamic strain. Experiment result show that the reflected intensity had linier relationships with dynamic strain. Based on these characteristics, we developed the FBG sensor to detect low frequency vibration. This sensor is designed by attaching the FBG on the bronze cantilever with dimensions of 85×3×0.5 mm. Measurement results showed that the sensor was able to detect vibrations in the frequency range of 7-10 Hz at temperature range of 25-45 ˚C. The measured frequency range is still within the frequency range of digging activity, therefore this vibration sensor can be applied for oil pipelines vandalisation detection system.

  2. Raman intensity and vibrational modes of armchair CNTs

    Science.gov (United States)

    Hur, Jaewoong; Stuart, Steven J.

    2017-07-01

    Raman intensity changes and frequency patterns have been studied using the various armchair (n, n) to understand the variations of bond polarizability, in regard to changing diameters, lengths, and the number of atoms in the (n, n). The Raman intensity trends of the (n, n) are validated by those of Cn isomers. For frequency trends, similar frequency patterns and frequency inward shifts for the (n, n) are characterized. Also, VDOS trends of the (n, n) expressing Raman modes are interpreted. The decomposition of vibrational modes in the (n, n) into radial, longitudinal, and tangential mode is beneficially used to recognize the distinct characteristics of vibrational modes.

  3. Perceptual Space of Superimposed Dual-Frequency Vibrations in the Hands.

    Science.gov (United States)

    Hwang, Inwook; Seo, Jeongil; Choi, Seungmoon

    2017-01-01

    The use of distinguishable complex vibrations that have multiple spectral components can improve the transfer of information by vibrotactile interfaces. We investigated the qualitative characteristics of dual-frequency vibrations as the simplest complex vibrations compared to single-frequency vibrations. Two psychophysical experiments were conducted to elucidate the perceptual characteristics of these vibrations by measuring the perceptual distances among single-frequency and dual-frequency vibrations. The perceptual distances of dual-frequency vibrations between their two frequency components along their relative intensity ratio were measured in Experiment I. The estimated perceptual spaces for three frequency conditions showed non-linear perceptual differences between the dual-frequency and single-frequency vibrations. A perceptual space was estimated from the measured perceptual distances among ten dual-frequency compositions and five single-frequency vibrations in Experiment II. The effect of the component frequency and the frequency ratio was revealed in the perceptual space. In a percept of dual-frequency vibration, the lower frequency component showed a dominant effect. Additionally, the perceptual difference among single-frequency and dual-frequency vibrations were increased with a low relative difference between two frequencies of a dual-frequency vibration. These results are expected to provide a fundamental understanding about the perception of complex vibrations to enrich the transfer of information using vibrotactile stimuli.

  4. Low-frequency wideband vibration energy harvesting by using frequency up-conversion and quin-stable nonlinearity

    Science.gov (United States)

    Wang, Chen; Zhang, Qichang; Wang, Wei

    2017-07-01

    This work presents models and experiments of an impact-driven and frequency up-converted wideband piezoelectric-based vibration energy harvester with a quintuple-well potential induced by the combination effect of magnetic nonlinearity and mechanical piecewise-linearity. Analysis shows that the interwell motions during coupled vibration period enable to increase electrical power output in comparison to conventional frequency up-conversion technology. Besides, the quintuple-well potential with shallower potential wells could extend the harvester's operating bandwidth to lower frequencies. Experiments demonstrate our proposed approach can dramatically boost the measured power of the energy harvester as much as 35 times while its lower cut-off frequency is two times lower than that of a conventional counterpart. These results reveal our proposed approach shows promise for powering portable wireless smart devices from low-intensity, low-frequency vibration sources.

  5. Frequency adjustable MEMS vibration energy harvester

    Science.gov (United States)

    Podder, P.; Constantinou, P.; Amann, A.; Roy, S.

    2016-10-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators.

  6. Frequency adjustable MEMS vibration energy harvester

    International Nuclear Information System (INIS)

    Podder, P; Constantinou, P; Roy, S; Amann, A

    2016-01-01

    Ambient mechanical vibrations offer an attractive solution for powering the wireless sensor nodes of the emerging “Internet-of-Things”. However, the wide-ranging variability of the ambient vibration frequencies pose a significant challenge to the efficient transduction of vibration into usable electrical energy. This work reports the development of a MEMS electromagnetic vibration energy harvester where the resonance frequency of the oscillator can be adjusted or tuned to adapt to the ambient vibrational frequency. Micro-fabricated silicon spring and double layer planar micro-coils along with sintered NdFeB micro-magnets are used to construct the electromagnetic transduction mechanism. Furthermore, another NdFeB magnet is adjustably assembled to induce variable magnetic interaction with the transducing magnet, leading to significant change in the spring stiffness and resonance frequency. Finite element analysis and numerical simulations exhibit substantial frequency tuning range (25% of natural resonance frequency) by appropriate adjustment of the repulsive magnetic interaction between the tuning and transducing magnet pair. This demonstrated method of frequency adjustment or tuning have potential applications in other MEMS vibration energy harvesters and micromechanical oscillators. (paper)

  7. Low intensity, high frequency vibration training to improve musculoskeletal function in a mouse model of Duchenne muscular dystrophy.

    Directory of Open Access Journals (Sweden)

    Susan A Novotny

    Full Text Available The objective of the study was to determine if low intensity, high frequency vibration training impacted the musculoskeletal system in a mouse model of Duchenne muscular dystrophy, relative to healthy mice. Three-week old wildtype (n = 26 and mdx mice (n = 22 were randomized to non-vibrated or vibrated (45 Hz and 0.6 g, 15 min/d, 5 d/wk groups. In vivo and ex vivo contractile function of the anterior crural and extensor digitorum longus muscles, respectively, were assessed following 8 wks of vibration. Mdx mice were injected 5 and 1 days prior to sacrifice with Calcein and Xylenol, respectively. Muscles were prepared for histological and triglyceride analyses and subcutaneous and visceral fat pads were excised and weighed. Tibial bones were dissected and analyzed by micro-computed tomography for trabecular morphometry at the metaphysis, and cortical geometry and density at the mid-diaphysis. Three-point bending tests were used to assess cortical bone mechanical properties and a subset of tibiae was processed for dynamic histomorphometry. Vibration training for 8 wks did not alter trabecular morphometry, dynamic histomorphometry, cortical geometry, or mechanical properties (P ≥ 0.34. Vibration did not alter any measure of muscle contractile function (P ≥ 0.12; however the preservation of muscle function and morphology in mdx mice indicates vibration is not deleterious to muscle lacking dystrophin. Vibrated mice had smaller subcutaneous fat pads (P = 0.03 and higher intramuscular triglyceride concentrations (P = 0.03. These data suggest that vibration training at 45 Hz and 0.6 g did not significantly impact the tibial bone and the surrounding musculature, but may influence fat distribution in mice.

  8. Low-frequency characteristics extension for vibration sensors

    Institute of Scientific and Technical Information of China (English)

    杨学山; 高峰; 候兴民

    2004-01-01

    Traditional magneto-electric vibration sensors and servo accelerometers have severe shortcomings when used to measure vibration where low frequency components predominate. A low frequency characteristic extension for velocity vibration sensors is presented in this paper. The passive circuit technology, active compensation technology and the closedcycle pole compensation technology are used to extend the measurable range and to improve low frequency characteristics of sensors. Thses three types of low frequency velocity vibration sensors have been developed and widely adopted in China.

  9. Various performance-enhancing effects from the same intensity of whole-body vibration training

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    Paohung Chung

    2017-09-01

    Conclusion: All frequency and amplitude settings in the 8-week whole-body vibration training increased muscle strength, but different settings resulted in various neuromuscular adaptations despite the same intensity.

  10. Tuning and sensitivity of the human vestibular system to low-frequency vibration.

    Science.gov (United States)

    Todd, Neil P McAngus; Rosengren, Sally M; Colebatch, James G

    2008-10-17

    Mechanoreceptive hair-cells of the vertebrate inner ear have a remarkable sensitivity to displacement, whether excited by sound, whole-body acceleration or substrate-borne vibration. In response to seismic or substrate-borne vibration, thresholds for vestibular afferent fibre activation have been reported in anamniotes (fish and frogs) in the range -120 to -90 dB re 1g. In this article, we demonstrate for the first time that the human vestibular system is also extremely sensitive to low-frequency and infrasound vibrations by making use of a new technique for measuring vestibular activation, via the vestibulo-ocular reflex (VOR). We found a highly tuned response to whole-head vibration in the transmastoid plane with a best frequency of about 100 Hz. At the best frequency we obtained VOR responses at intensities of less than -70 dB re 1g, which was 15 dB lower than the threshold of hearing for bone-conducted sound in humans at this frequency. Given the likely synaptic attenuation of the VOR pathway, human receptor sensitivity is probably an order of magnitude lower, thus approaching the seismic sensitivity of the frog ear. These results extend our knowledge of vibration-sensitivity of vestibular afferents but also are remarkable as they indicate that the seismic sensitivity of the human vestibular system exceeds that of the cochlea for low-frequencies.

  11. Band Width of Acoustic Resonance Frequency Relatively Natural Frequency of Fuel Rod Vibration

    Energy Technology Data Exchange (ETDEWEB)

    Proskuryakov, Konstantin Nicolaevich; Moukhine, V.S.; Novikov, K.S.; Galivets, E.Yu. [MPEI - TU, 14, Krasnokazarmennaya str., Moscow, 111250 (Russian Federation)

    2009-06-15

    In flow induced vibrations the fluid flow is the energy source that causes vibration. Acoustic resonance in piping may lead to severe problems due to over-stressing of components or significant losses of efficiency. Steady oscillatory flow in NPP primary loop can be induced by the pulsating flow introduced by reactor circulating pump or may be set up by self-excitation. Dynamic forces generated by the turbulent flow of coolant in reactor cores cause fuel rods (FR) and fuel assembly (FA) to vibrate. Flow-induced FR and FA vibrations can generally be broken into three groups: large amplitude 'resonance type' vibrations, which can cause immediate rod failure or severe damage to the rod and its support structure, middle amplitude 'within bandwidth of resonance frequency type' vibrations responsible for more gradual wear and fatigue at the contact surface between the fuel cladding and rod support and small amplitude vibrations, 'out of bandwidth of resonance frequency type' responsible for permissible wear and fatigue at the contact surface between the fuel cladding and rod support. Ultimately, these vibration types can result in a cladding breach, and therefore must be accounted for in the thermal hydraulic design of FR and FA and reactor internals. In paper the technique of definition of quality factor (Q) of acoustic contour of the coolant is presented. The value of Q defines a range of frequencies of acoustic fluctuations of the coolant within which the resonance of oscillations of the structure and the coolant is realized. Method of evaluation of so called band width (BW) of acoustic resonance frequency is worked out and presented in the paper. BW characterises the range of the frequency of coolant pressure oscillations within which the frequency of coolant pressure oscillations matches the fuel assembly's natural frequency of vibration (its resonance frequency). Paper show the way of detuning acoustic resonance from natural

  12. Transverse Beam Halo Measurements at High Intensity Neutrino Source (HINS) using Vibrating Wire Monitor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, M.; Hanna, B.; Scarpine, V.; Shiltsev, V.; Steimel, J.; Artinian, S.; Arutunian, S.

    2015-02-26

    The measurement and control of beam halos will be critical for the applications of future high-intensity hadron linacs. In particular, beam profile monitors require a very high dynamic range when used for the transverse beam halo measurements. In this study, the Vibrating Wire Monitor (VWM) with aperture 60 mm was installed at the High Intensity Neutrino Source (HINS) front-end to measure the transverse beam halo. A vibrating wire is excited at its resonance frequency with the help of a magnetic feedback loop, and the vibrating and sensitive wires are connected through a balanced arm. The sensitive wire is moved into the beam halo region by a stepper motor controlled translational stage. We study the feasibility of the vibrating wire for the transverse beam halo measurements in the low-energy front-end of the proton linac.

  13. Nonlinear convergence active vibration absorber for single and multiple frequency vibration control

    Science.gov (United States)

    Wang, Xi; Yang, Bintang; Guo, Shufeng; Zhao, Wenqiang

    2017-12-01

    This paper presents a nonlinear convergence algorithm for active dynamic undamped vibration absorber (ADUVA). The damping of absorber is ignored in this algorithm to strengthen the vibration suppressing effect and simplify the algorithm at the same time. The simulation and experimental results indicate that this nonlinear convergence ADUVA can help significantly suppress vibration caused by excitation of both single and multiple frequency. The proposed nonlinear algorithm is composed of equivalent dynamic modeling equations and frequency estimator. Both the single and multiple frequency ADUVA are mathematically imitated by the same mechanical structure with a mass body and a voice coil motor (VCM). The nonlinear convergence estimator is applied to simultaneously satisfy the requirements of fast convergence rate and small steady state frequency error, which are incompatible for linear convergence estimator. The convergence of the nonlinear algorithm is mathematically proofed, and its non-divergent characteristic is theoretically guaranteed. The vibration suppressing experiments demonstrate that the nonlinear ADUVA can accelerate the convergence rate of vibration suppressing and achieve more decrement of oscillation attenuation than the linear ADUVA.

  14. Eulerian frequency analysis of structural vibrations from high-speed video

    International Nuclear Information System (INIS)

    Venanzoni, Andrea; De Ryck, Laurent; Cuenca, Jacques

    2016-01-01

    An approach for the analysis of the frequency content of structural vibrations from high-speed video recordings is proposed. The techniques and tools proposed rely on an Eulerian approach, that is, using the time history of pixels independently to analyse structural motion, as opposed to Lagrangian approaches, where the motion of the structure is tracked in time. The starting point is an existing Eulerian motion magnification method, which consists in decomposing the video frames into a set of spatial scales through a so-called Laplacian pyramid [1]. Each scale — or level — can be amplified independently to reconstruct a magnified motion of the observed structure. The approach proposed here provides two analysis tools or pre-amplification steps. The first tool provides a representation of the global frequency content of a video per pyramid level. This may be further enhanced by applying an angular filter in the spatial frequency domain to each frame of the video before the Laplacian pyramid decomposition, which allows for the identification of the frequency content of the structural vibrations in a particular direction of space. This proposed tool complements the existing Eulerian magnification method by amplifying selectively the levels containing relevant motion information with respect to their frequency content. This magnifies the displacement while limiting the noise contribution. The second tool is a holographic representation of the frequency content of a vibrating structure, yielding a map of the predominant frequency components across the structure. In contrast to the global frequency content representation of the video, this tool provides a local analysis of the periodic gray scale intensity changes of the frame in order to identify the vibrating parts of the structure and their main frequencies. Validation cases are provided and the advantages and limits of the approaches are discussed. The first validation case consists of the frequency content

  15. MOLECULAR STRUCTURE AND VIBRATIONAL FREQUENCIES OF

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    Fatih UCUN

    2009-02-01

    Full Text Available Abstract: The molecular structure, vibrational frequencies and the corresponding assignments of N-aminophthalimide (NAPH in the ground state have been calculated using the Hartree-Fock (HF and density functional methods (B3LYP with 6-31G (d, p basis set. The calculations were utilized in the CS symmetry of NAPH. The obtained vibrational frequencies and optimized geometric parameters (bond lengths and bond angles were seen to be in good agreement with the experimental data. The comparison of the observed and calculated results showed that B3LYP is superior to the scaled HF method. Theoretical infrared intensities and Raman activities were also reported. Key words: N-aminophthalimide; vibrations; IR spectra; Raman spectra; HF; DFT N-AMİNOFİTALOMİD'İN MOLEKÜLER YAPISI VE TİTREŞİM FREKANSLARI Özet: Temel haldeki N-aminofitalamidin (NAPH moleküler yapısı, titreşim frekansları ve uygun mod tanımlamaları, 6-31 G (d, p temel setli Hartree-Fock (HF ve yoğunluk fonksiyonu metodları (B3LYP kullanılarak hesaplandı. Hesaplamalar, NAPH'ın CS simetrisine uyarlandı. Elde edilen titreşim frekansları ve optimize geometrik parametreleri (bağ uzunlukları ve bağ açıları, deneysel değerlerle iyi bir uyum içinde olduğu görüldü. Deneysel ve teorik sonuçların karşılaştırılması, B3LYP'nin HF metodundan daha üstün olduğunu gösterdi. Ayrıca teorik infrared şiddetleri ve Raman aktiviteleri verildi. Anahtar Kelimeler: N-aminofitalamidin; titreşimler; IR spektrumu; Raman Spektrumu; HF; DFT

  16. An innovative MRE absorber with double natural frequencies for wide frequency bandwidth vibration absorption

    International Nuclear Information System (INIS)

    Sun, Shuaishuai; Yang, Jian; Li, Weihua; Alici, Gursel; Deng, Huaxia; Du, Haiping; Yan, Tianhong

    2016-01-01

    A new design of adaptive tuned vibration absorber was proposed in this study for vibration reduction. The innovation of the new absorber is the adoption of the eccentric mass on the top of the multilayered magnetorheological elastomer (MRE) structure so that this proposed absorber has two vibration modes: one in the torsional direction and the other in translational direction. This property enables the absorber to expand its effective bandwidth and to be more capable of reducing the vibrations especially dealing with those vibrations with multi-frequencies. The innovative MRE absorber was designed and tested on a horizontal vibration table. The test results illustrate that the MRE absorber realized double natural frequencies, both of which are controllable. Inertia’s influence on the dynamic behavior of the absorber is also investigated in order to guide the design of the innovative MRE absorber. Additionally, the experimentally obtained natural frequencies coincide with the theoretical data, which sufficiently verifies the feasibility of this new design. The last part in terms of the vibration absorption ability also proves that both of these two natural frequencies play a great role in absorbing vibration energy. (paper)

  17. Capacitance-based frequency adjustment of micro piezoelectric vibration generator.

    Science.gov (United States)

    Mao, Xinhua; He, Qing; Li, Hong; Chu, Dongliang

    2014-01-01

    Micro piezoelectric vibration generator has a wide application in the field of microelectronics. Its natural frequency is unchanged after being manufactured. However, resonance cannot occur when the natural frequencies of a piezoelectric generator and the source of vibration frequency are not consistent. Output voltage of the piezoelectric generator will sharply decline. It cannot normally supply power for electronic devices. In order to make the natural frequency of the generator approach the frequency of vibration source, the capacitance FM technology is adopted in this paper. Different capacitance FM schemes are designed by different locations of the adjustment layer. The corresponding capacitance FM models have been established. Characteristic and effect of the capacitance FM have been simulated by the FM model. Experimental results show that the natural frequency of the generator could vary from 46.5 Hz to 42.4 Hz when the bypass capacitance value increases from 0 nF to 30 nF. The natural frequency of a piezoelectric vibration generator could be continuously adjusted by this method.

  18. Capacitance-Based Frequency Adjustment of Micro Piezoelectric Vibration Generator

    Directory of Open Access Journals (Sweden)

    Xinhua Mao

    2014-01-01

    Full Text Available Micro piezoelectric vibration generator has a wide application in the field of microelectronics. Its natural frequency is unchanged after being manufactured. However, resonance cannot occur when the natural frequencies of a piezoelectric generator and the source of vibration frequency are not consistent. Output voltage of the piezoelectric generator will sharply decline. It cannot normally supply power for electronic devices. In order to make the natural frequency of the generator approach the frequency of vibration source, the capacitance FM technology is adopted in this paper. Different capacitance FM schemes are designed by different locations of the adjustment layer. The corresponding capacitance FM models have been established. Characteristic and effect of the capacitance FM have been simulated by the FM model. Experimental results show that the natural frequency of the generator could vary from 46.5 Hz to 42.4 Hz when the bypass capacitance value increases from 0 nF to 30 nF. The natural frequency of a piezoelectric vibration generator could be continuously adjusted by this method.

  19. Effect of low-frequency vibrations on speckle interferometry fringes

    International Nuclear Information System (INIS)

    Vikram, C.S.; Pechersky, M.J.

    1998-01-01

    The effects of low-frequency vibrations on speckle correlation fringes have been investigated. The relatively short capture time of the camera in the low-frequency case may yield usable fringe contrast in spite of vibration. It has been shown that the fringes also shift due to the vibration. The study is in agreement with experimental observations of good-contrast correlation fringes even if the object is not on a vibration-isolated table. Some such experimental observations are also presented. copyright 1998 Society of Photo-Optical Instrumentation Engineers

  20. Energy Expenditure and Substrate Oxidation in Response to Side-Alternating Whole Body Vibration across Three Commonly-Used Vibration Frequencies.

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    Elie-Jacques Fares

    Full Text Available There is increasing recognition about the importance of enhancing energy expenditure (EE for weight control through increases in low-intensity physical activities comparable with daily life (1.5-4 METS. Whole-body vibration (WBV increases EE modestly and could present both a useful adjuvant for obesity management and tool for metabolic phenotyping. However, it is unclear whether a "dose-response" exists between commonly-used vibration frequencies (VF and EE, nor if WBV influences respiratory quotient (RQ, and hence substrate oxidation. We aimed to investigate the EE-VF and RQ-VF relationships across three different frequencies (30, 40, and 50Hz.EE and RQ were measured in 8 healthy young adults by indirect calorimetry at rest, and subsequently during side-alternating WBV at one of 3 VFs (30, 40, and 50 Hz. Each frequency was assessed over 5 cycles of intermittent WBV (30s vibration/30s rest, separated by 5 min seated rest. During the WBV participants stood on the platform with knees flexed sufficiently to maintain comfort, prevent transmission of vibration to the upper body, and minimise voluntary physical exertion. Repeatability was assessed across 3 separate days in a subset of 4 individuals. In order to assess any sequence/habituation effect, an additional group of 6 men underwent 5 cycles of intermittent WBV (30s vibration/30s rest at 40 Hz, separated by 5 min seated rest.Side-alternating WBV increased EE relative to standing, non-vibration levels (+36%, p<0.001. However, no differences in EE were observed across VFs. Similarly, no effect of VF on RQ was found, nor did WBV alter RQ relative to standing without vibration.No relationship could be demonstrated between EE and VF in the range of 30-50Hz, and substrate oxidation did not change in response to WBV. Furthermore, the thermogenic effect of intermittent WBV, whilst robust, was quantitatively small (<2 METS.

  1. S-matrix analysis of vibrational and alignment effects in intense-field multiphoton ionization of molecules

    International Nuclear Information System (INIS)

    Requate, A.

    2007-03-01

    Theoretical analysis of the vibrational excitation of small molecules during multiphoton ionization in intense laser fields of optical and infrared frequencies. Analysis of the alignment dependence of the electron impact ionization of diatomic molecules in the presence of an intense laser field as the final step in the process of Nonsequential Double Ionization. Quantum mechanical description using S-matrix theory in Strong Field Approximation (SFA), i.e. beyond perturbation theory. (orig.)

  2. S-matrix analysis of vibrational and alignment effects in intense-field multiphoton ionization of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Requate, A

    2007-03-15

    Theoretical analysis of the vibrational excitation of small molecules during multiphoton ionization in intense laser fields of optical and infrared frequencies. Analysis of the alignment dependence of the electron impact ionization of diatomic molecules in the presence of an intense laser field as the final step in the process of Nonsequential Double Ionization. Quantum mechanical description using S-matrix theory in Strong Field Approximation (SFA), i.e. beyond perturbation theory. (orig.)

  3. Orientations of nonlocal vibrational modes from combined experimental and theoretical sum frequency spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chase, Hilary M.; Chen, Shunli; Fu, Li; Upshur, Mary Alice; Rudshteyn, Benjamin; Thomson, Regan J.; Wang, Hong-Fei; Batista, Victor S.; Geiger, Franz M.

    2017-09-01

    Inferring molecular orientations from vibrational sum frequency generation (SFG) spectra is challenging in polarization combinations that result in low signal intensities, or when the local point group symmetry approximation fails. While combining experiments with density functional theory (DFT) could overcome this problem, the scope of the combined method has yet to be established. Here, we assess its feasibility of determining the distributions of molecular orientations for one monobasic ester, two epoxides and three alcohols at the vapor/fused silica interface. We find that molecular orientations of nonlocal vibrational modes cannot be determined using polarization-resolved SFG measurements alone.

  4. Theory of sum-frequency generation spectroscopy of adsorbed molecules using the density matrix method-broadband vibrational sum-frequency generation and applications

    International Nuclear Information System (INIS)

    Bonn, M; Ueba, H; Wolf, M

    2005-01-01

    A generalized theory of frequency- and time-resolved vibrational sum-frequency generation (SFG) spectroscopy of adsorbates at surfaces is presented using the density matrix formalism. Our theoretical treatment is specifically aimed at addressing issues that accompany the relatively novel SFG approach using broadband infrared pulses. The ultrashort duration of these pulses makes them ideally suited for time-resolved investigations, for which we present a complete theoretical treatment. A second key characteristic of these pulses is their large bandwidth and high intensity, which allow for highly non-linear effects, including vibrational ladder climbing of surface vibrations. We derive general expressions relating the density matrix to SFG spectra, and apply these expressions to specific experimental results by solving the coupled optical Bloch equations of the density matrix elements. Thus, we can theoretically reproduce recent experimentally demonstrated hot band SFG spectra using femtosecond broadband infrared excitation of carbon monoxide (CO) on a Ru(001) surface

  5. A broadband frequency-tunable dynamic absorber for the vibration control of structures

    International Nuclear Information System (INIS)

    Komatsuzaki, T; Inoue, T; Terashima, O

    2016-01-01

    A passive-type dynamic vibration absorber (DVA) is basically a mass-spring system that suppresses the vibration of a structure at a particular frequency. Since the natural frequency of the DVA is usually tuned to a frequency of particular excitation, the DVA is especially effective when the excitation frequency is close to the natural frequency of the structure. Fixing the physical properties of the DVA limits the application to a narrowband, harmonically excited vibration problem. A frequency-tunable DVA that can modulate its stiffness provides adaptability to the vibration control device against non-stationary disturbances. In this paper, we suggest a broadband frequency-tunable DVA whose natural frequency can be extended by 300% to the nominal value using the magnetorheological elastomers (MREs). The frequency adjustability of the proposed absorber is first shown. The real-time vibration control performance of the frequency-tunable absorber for an acoustically excited plate having multiple resonant peaks is then evaluated. Investigations show that the vibration of the structure can be effectively reduced with an improved performance by the DVA in comparison to the conventional passive- type absorber. (paper)

  6. Difference frequency generation spectroscopy as a vibrational optical activity measurement tool.

    Science.gov (United States)

    Cheon, Sangheon; Cho, Minhaeng

    2009-03-19

    Vibrational optical activity (VOA) of chiral molecules in condensed phases can be studied by using vibrational circular dichroism and Raman optical activity measurement techniques. Recently, IR-vis sum frequency generation has shown to be an alternative VOA measurement method. Such a three-wave-mixing method employing a polarization modulation technique can be a potentially useful VOA measurement tool. Here, a theoretical description of difference frequency generation (DFG) employing circularly polarized visible radiations is presented. Frequency scanning to obtain a VOA-DFG spectrum is achieved by controlling the difference between the two electronically nonresonant incident radiation frequencies. If the two incident beams are linearly polarized and their polarization directions are perpendicular to each other, one can selectively measure the all-electric-dipole-allowed chiral component of the DFG susceptibility. In addition, by using circularly polarized beams and taking the DFG difference intensity signal, which is defined as the difference between left and right circularly polarized DFG signals, additional chiral susceptibility components originating from the electric quadrupole transition can be measured. The DFG as a novel VOA measurement technique for solution samples containing chiral molecules will therefore be a useful coherent spectroscopic tool for determining absolute configuration of chiral molecules in condensed phases.

  7. Long Range Dependence Prognostics for Bearing Vibration Intensity Chaotic Time Series

    Directory of Open Access Journals (Sweden)

    Qing Li

    2016-01-01

    Full Text Available According to the chaotic features and typical fractional order characteristics of the bearing vibration intensity time series, a forecasting approach based on long range dependence (LRD is proposed. In order to reveal the internal chaotic properties, vibration intensity time series are reconstructed based on chaos theory in phase-space, the delay time is computed with C-C method and the optimal embedding dimension and saturated correlation dimension are calculated via the Grassberger–Procaccia (G-P method, respectively, so that the chaotic characteristics of vibration intensity time series can be jointly determined by the largest Lyapunov exponent and phase plane trajectory of vibration intensity time series, meanwhile, the largest Lyapunov exponent is calculated by the Wolf method and phase plane trajectory is illustrated using Duffing-Holmes Oscillator (DHO. The Hurst exponent and long range dependence prediction method are proposed to verify the typical fractional order features and improve the prediction accuracy of bearing vibration intensity time series, respectively. Experience shows that the vibration intensity time series have chaotic properties and the LRD prediction method is better than the other prediction methods (largest Lyapunov, auto regressive moving average (ARMA and BP neural network (BPNN model in prediction accuracy and prediction performance, which provides a new approach for running tendency predictions for rotating machinery and provide some guidance value to the engineering practice.

  8. Applying Low-Frequency Vibration for the Experimental Investigation of Clutch Hub Forming

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    De’an Meng

    2018-05-01

    Full Text Available A vibration-assisted plastic-forming method was proposed, and its influence on clutch hub forming process was investigated. The experiments were conducted on a vibration-assisted hydraulic extrusion press with adjustable frequency and amplitude. Vibration frequency and amplitude were considered in investigating the effect of vibration on forming load and surface quality. Results showed that applying vibration can effectively reduce forming force and improve surface quality. The drop in forming load was proportional to the vibration frequency and amplitude, and the load decreased by up to 25%. Such reduction in forming load raised with amplitude increase because the increase in amplitude would accelerate punch relative speed, which then weakened the adhesion between workpiece and dies. By increasing the vibration frequency, the punch movement was enhanced, and the number of attempts to drag the lubricant out of the pits was increased. In this manner, the lubrication condition was improved greatly. The 3D surface topography testing confirmed the assumption. Moreover, vibration frequency exerted a more significant effect on the forming load reduction than vibration amplitude.

  9. Impact-driven, frequency up-converting coupled vibration energy harvesting device for low frequency operation

    International Nuclear Information System (INIS)

    Gu, Lei; Livermore, Carol

    2011-01-01

    This paper presents experiments and models of an energy harvesting device in which a low frequency resonator impacts a high frequency energy harvesting resonator, resulting in energy harvesting predominantly at the system's coupled vibration frequency. Analysis shows that a reduced mechanical damping ratio during coupled vibration enables increased electrical power generation as compared with conventional technology. Experiments demonstrate that the efficiency of electrical power transfer is significantly improved with the coupled vibration approach. An average power output of 0.43 mW is achieved under 0.4g acceleration at 8.2 Hz, corresponding to a power density of 25.5 µW cm −3 . The measured power and power density at the resonant frequency are respectively 4.8 times and 13 times the measured peak values for a conventional harvester created from a low frequency beam alone

  10. Low frequency vibration tests on a floating slab track in an underground laboratory

    Institute of Scientific and Technical Information of China (English)

    De-yun DING; Wei-ning LIU; Ke-fei LI; Xiao-jing SUN; Wei-feng LIU

    2011-01-01

    Low frequency vibrations induced by underground railways have attracted increasing attention in recent years. To obtain the characteristics of low frequency vibrations and the low frequency performance of a floating slab track (FST), low frequency vibration tests on an FST in an underground laboratory at Beijing Jiaotong University were carried out. The FST and an unbalanced shaker SBZ30 for dynamic simulation were designed for use in low frequency vibration experiments. Vibration measurements were performed on the bogie of the unbalanced shaker, the rail, the slab, the tunnel invert, the tunnel wall, the tunnel apex, and on the ground surface at distances varying from 0 to 80 m from the track. Measurements were also made on several floors of an adjacent building. Detailed results of low frequency vibration tests were reported. The attenuation of low frequency vibrations with the distance from the track was presented, as well as the responses of different floors of the building. The experimental results could be regarded as a reference for developing methods to control low frequency vibrations and for adopting countermeasures.

  11. Theoretical study of sum-frequency vibrational spectroscopy on limonene surface

    International Nuclear Information System (INIS)

    Zheng, Ren-Hui; Liu, Hao; Jing, Yuan-Yuan; Wang, Bo-Yang; Shi, Qiang; Wei, Wen-Mei

    2014-01-01

    By combining molecule dynamics (MD) simulation and quantum chemistry computation, we calculate the surface sum-frequency vibrational spectroscopy (SFVS) of R-limonene molecules at the gas-liquid interface for SSP, PPP, and SPS polarization combinations. The distributions of the Euler angles are obtained using MD simulation, the ψ-distribution is between isotropic and Gaussian. Instead of the MD distributions, different analytical distributions such as the δ-function, Gaussian and isotropic distributions are applied to simulate surface SFVS. We find that different distributions significantly affect the absolute SFVS intensity and also influence on relative SFVS intensity, and the δ-function distribution should be used with caution when the orientation distribution is broad. Furthermore, the reason that the SPS signal is weak in reflected arrangement is discussed

  12. Theoretical study of sum-frequency vibrational spectroscopy on limonene surface

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Ren-Hui, E-mail: zrh@iccas.ac.cn; Liu, Hao; Jing, Yuan-Yuan; Wang, Bo-Yang; Shi, Qiang [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190 (China); Wei, Wen-Mei [Department of Chemistry, College of Basic Medicine, Anhui Medical University, Hefei, Anhui 230032 (China)

    2014-03-14

    By combining molecule dynamics (MD) simulation and quantum chemistry computation, we calculate the surface sum-frequency vibrational spectroscopy (SFVS) of R-limonene molecules at the gas-liquid interface for SSP, PPP, and SPS polarization combinations. The distributions of the Euler angles are obtained using MD simulation, the ψ-distribution is between isotropic and Gaussian. Instead of the MD distributions, different analytical distributions such as the δ-function, Gaussian and isotropic distributions are applied to simulate surface SFVS. We find that different distributions significantly affect the absolute SFVS intensity and also influence on relative SFVS intensity, and the δ-function distribution should be used with caution when the orientation distribution is broad. Furthermore, the reason that the SPS signal is weak in reflected arrangement is discussed.

  13. Frequency Up-Converted Low Frequency Vibration Energy Harvester Using Trampoline Effect

    International Nuclear Information System (INIS)

    Ju, S; Chae, S H; Choi, Y; Jun, S; Park, S M; Lee, S; Ji, C-H; Lee, H W

    2013-01-01

    This paper presents a non-resonant vibration energy harvester based on magnetoelectric transduction mechanism and mechanical frequency up-conversion using trampoline effect. The harvester utilizes a freely movable spherical permanent magnet which bounces off the aluminum springs integrated at both ends of the cavity, achieving frequency up-conversion from low frequency input vibration. Moreover, bonding method of magnetoelectric laminate composite has been optimized to provide higher strain to piezoelectric material and thus obtain a higher output voltage. A proof-of-concept energy harvesting device has been fabricated and tested. Maximum open-circuit voltage of 11.2V has been obtained and output power of 0.57μW has been achieved for a 50kΩ load, when the fabricated energy harvester was hand-shaken

  14. Frequency Up-Converted Low Frequency Vibration Energy Harvester Using Trampoline Effect

    Science.gov (United States)

    Ju, S.; Chae, S. H.; Choi, Y.; Jun, S.; Park, S. M.; Lee, S.; Lee, H. W.; Ji, C.-H.

    2013-12-01

    This paper presents a non-resonant vibration energy harvester based on magnetoelectric transduction mechanism and mechanical frequency up-conversion using trampoline effect. The harvester utilizes a freely movable spherical permanent magnet which bounces off the aluminum springs integrated at both ends of the cavity, achieving frequency up-conversion from low frequency input vibration. Moreover, bonding method of magnetoelectric laminate composite has been optimized to provide higher strain to piezoelectric material and thus obtain a higher output voltage. A proof-of-concept energy harvesting device has been fabricated and tested. Maximum open-circuit voltage of 11.2V has been obtained and output power of 0.57μW has been achieved for a 50kΩ load, when the fabricated energy harvester was hand-shaken.

  15. [Short-term memory characteristics of vibration intensity tactile perception on human wrist].

    Science.gov (United States)

    Hao, Fei; Chen, Li-Juan; Lu, Wei; Song, Ai-Guo

    2014-12-25

    In this study, a recall experiment and a recognition experiment were designed to assess the human wrist's short-term memory characteristics of tactile perception on vibration intensity, by using a novel homemade vibrotactile display device based on the spatiotemporal combination vibration of multiple micro vibration motors as a test device. Based on the obtained experimental data, the short-term memory span, recognition accuracy and reaction time of vibration intensity were analyzed. From the experimental results, some important conclusions can be made: (1) The average short-term memory span of tactile perception on vibration intensity is 3 ± 1 items; (2) The greater difference between two adjacent discrete intensities of vibrotactile stimulation is defined, the better average short-term memory span human wrist gets; (3) There is an obvious difference of the average short-term memory span on vibration intensity between the male and female; (4) The mechanism of information extraction in short-term memory of vibrotactile display is to traverse the scanning process by comparison; (5) The recognition accuracy and reaction time performance of vibrotactile display compares unfavourably with that of visual and auditory. The results from this study are important for designing vibrotactile display coding scheme.

  16. Micro-scale piezoelectric vibration energy harvesting: From fixed-frequency to adaptable-frequency devices

    Science.gov (United States)

    Miller, Lindsay Margaret

    hundred milliwatts and are falling steadily as improvements are made, it is feasible to use energy harvesting to power WSNs. This research begins by presenting the results of a thorough survey of ambient vibrations in the machine room of a large campus building, which found that ambient vibrations are low frequency, low amplitude, time varying, and multi-frequency. The modeling and design of fixed-frequency micro scale energy harvesters are then presented. The model is able to take into account rotational inertia of the harvester's proof mass and it accepts arbitrary measured acceleration input, calculating the energy harvester's voltage as an output. The fabrication of the micro electromechanical system (MEMS) energy harvesters is discussed and results of the devices harvesting energy from ambient vibrations are presented. The harvesters had resonance frequencies ranging from 31 - 232 Hz, which was the lowest reported in literature for a MEMS device, and produced 24 pW/g2 - 10 nW/g2 of harvested power from ambient vibrations. A novel method for frequency modification of the released harvester devices using a dispenser printed mass is then presented, demonstrating a frequency shift of 20 Hz. Optimization of the MEMS energy harvester connected to a resistive load is then presented, finding that the harvested power output can be increased to several microwatts with the optimized design as long as the driving frequency matches the harvester's resonance frequency. A framework is then presented to allow a similar optimization to be conducted with the harvester connected to a synchronously switched pre-bias circuit. With the realization that the optimized energy harvester only produces usable amounts of power if the resonance frequency and driving frequency match, which is an unrealistic situation in the case of ambient vibrations which change over time and are not always known a priori, an adaptable-frequency energy harvester was designed. The adaptable-frequency harvester

  17. A vibration energy harvesting device with bidirectional resonance frequency tunability

    International Nuclear Information System (INIS)

    Challa, Vinod R; Prasad, M G; Shi Yong; Fisher, Frank T

    2008-01-01

    Vibration energy harvesting is an attractive technique for potential powering of wireless sensors and low power devices. While the technique can be employed to harvest energy from vibrations and vibrating structures, a general requirement independent of the energy transfer mechanism is that the vibration energy harvesting device operate in resonance at the excitation frequency. Most energy harvesting devices developed to date are single resonance frequency based, and while recent efforts have been made to broaden the frequency range of energy harvesting devices, what is lacking is a robust tunable energy harvesting technique. In this paper, the design and testing of a resonance frequency tunable energy harvesting device using a magnetic force technique is presented. This technique enabled resonance tuning to ± 20% of the untuned resonant frequency. In particular, this magnetic-based approach enables either an increase or decrease in the tuned resonant frequency. A piezoelectric cantilever beam with a natural frequency of 26 Hz is used as the energy harvesting cantilever, which is successfully tuned over a frequency range of 22–32 Hz to enable a continuous power output 240–280 µW over the entire frequency range tested. A theoretical model using variable damping is presented, whose results agree closely with the experimental results. The magnetic force applied for resonance frequency tuning and its effect on damping and load resistance have been experimentally determined

  18. Active Low-frequency Vertical Vibration Isolation System for Precision Measurements

    Institute of Scientific and Technical Information of China (English)

    WU Kang; LI Gang; HU Hua; WANG Lijun

    2017-01-01

    Low-frequency vertical vibration isolation systems play important roles in precision measurements to reduce seismic and environmental vibration noise.Several types of active vibration isolation systems have been developed.However,few researches focus on how to optimize the test mass install position in order to improve the vibration transmissibility.An active low-frequency vertical vibration isolation system based on an earlier instrument,the Super Spring,is designed and implemented.The system,which is simple and compact,consists of two stages:a parallelogram-shaped linkage to ensure vertical motion,and a simple spring-mass system.The theoretical analysis of the vibration isolation system is presented,including terms erroneously ignored before.By carefully choosing the mechanical parameters according to the above analysis and using feedback control,the resonance frequency of the system is reduced from 2.3 to 0.03 Hz,a reduction by a factor of more than 75.The vibration isolation system is installed as an inertial reference in an absolute gravimeter,where it improved the scatter of the absolute gravity values by a factor of 5.The experimental results verifies the improved performance of the isolation system,making it particularly suitable for precision experiments.The improved vertical vibration isolation system can be used as a prototype for designing high-performance active vertical isolation systems.An improved theoretical model of this active vibration isolation system with beam-pivot configuration is proposed,providing fundamental guidelines for vibration isolator design and assembling.

  19. Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

    Science.gov (United States)

    Zhang, Zhengyi; Liu, Chuntong; Li, Hongcai; He, Zhenxin; Zhao, Xiaofeng

    2017-06-01

    In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

  20. Enhancement to Non-Contacting Stress Measurement of Blade Vibration Frequency

    Science.gov (United States)

    Platt, Michael; Jagodnik, John

    2011-01-01

    A system for turbo machinery blade vibration has been developed that combines time-of-arrival sensors for blade vibration amplitude measurement and radar sensors for vibration frequency and mode identification. The enabling technology for this continuous blade monitoring system is the radar sensor, which provides a continuous time series of blade displacement over a portion of a revolution. This allows the data reduction algorithms to directly calculate the blade vibration frequency and to correctly identify the active modes of vibration. The work in this project represents a significant enhancement in the mode identification and stress calculation accuracy in non-contacting stress measurement system (NSMS) technology when compared to time-of-arrival measurements alone.

  1. Circularly polarized infrared and visible sum-frequency-generation spectroscopy: Vibrational optical activity measurement

    International Nuclear Information System (INIS)

    Cheon, Sangheon; Cho, Minhaeng

    2005-01-01

    Vibrational optical activity spectroscopies utilizing either circularly polarized ir or circularly polarized visible beams were theoretically investigated by considering the infrared and visible sum-frequency-generation (IV-SFG) schemes. In addition to the purely electric dipole-allowed chiral component of the IV-SFG susceptibility, the polarizability-electric quadrupole hyperpolarizability term also contributes to the vibrationally resonant IV-SFG susceptibility. The circular-intensity-difference signal is shown to be determined by the interferences between the all-electric dipole-allowed chiral component and the polarizability-electric-dipole or electric-dipole-electric-quadrupole Raman optical activity tensor components. The circularly polarized SFG methods are shown to be potentially useful coherent spectroscopic tools for determining absolute configurations of chiral molecules in condensed phases

  2. Molecular structures and vibrational frequencies of xanthine and its methyl derivatives (caffeine and theobromine) by ab initio Hartree-Fock and density functional theory calculations

    Science.gov (United States)

    Ucun, Fatih; Sağlam, Adnan; Güçlü, Vesile

    2007-06-01

    The molecular structures, vibrational frequencies and corresponding vibrational assignments of xanthine and its methyl derivatives (caffeine and theobromine) have been calculated using ab initio Hartree-Fock (HF) and density functional theory (B3LYP) methods with 6-31G(d, p) basis set level. The calculations were utilized to the CS symmetries of the molecules. The obtained vibrational frequencies and optimised geometric parameters (bond lengths and bond angles) were seen to be well agreement with the experimental data. The used scale factors which have been obtained the ratio of the frequency values of the strongest peaks in the calculated and experimental spectra seem to cause the gained vibrations well corresponding to the experimental ones. Theoretical infrared intensities and Raman activities are also reported.

  3. A Sub-Hertz, Low-Frequency Vibration Isolation Platform

    Science.gov (United States)

    Ortiz, Gerardo, G.; Farr, William H.; Sannibale, Virginio

    2011-01-01

    One of the major technical problems deep-space optical communication (DSOC) systems need to solve is the isolation of the optical terminal from vibrations produced by the spacecraft navigational control system and by the moving parts of onboard instruments. Even under these vibration perturbations, the DSOC transceivers (telescopes) need to be pointed l000 fs of times more accurately than an RF communication system (parabolic antennas). Mechanical resonators have been extensively used to provide vibration isolation for groundbased, airborne, and spaceborne payloads. The effectiveness of these isolation systems is determined mainly by the ability of designing a mechanical oscillator with the lowest possible resonant frequency. The Low-Frequency Vibration Isolation Platform (LFVIP), developed during this effort, aims to reduce the resonant frequency of the mechanical oscillators into the sub-Hertz region in order to maximize the passive isolation afforded by the 40 dB/decade roll-off response of the resonator. The LFVIP also provides tip/tilt functionality for acquisition and tracking of a beacon signal. An active control system is used for platform positioning and for dampening of the mechanical oscillator. The basic idea in the design of the isolation platform is to use a passive isolation strut with an approximately equal to 100-mHz resonance frequency. This will extend the isolation range to lower frequencies. The harmonic oscillator is a second-order lowpass filter for mechanical disturbances. The resonance quality depends on the dissipation mechanisms, which are mainly hysteretic because of the low resonant frequency and the absence of any viscous medium. The LFVIP system is configured using the well-established Stewart Platform, which consists of a top platform connected to a base with six extensible struts (see figure). The struts are attached to the base and to the platform via universal joints, which permit the extension and contraction of the struts. The

  4. Investigation into high-frequency-vibration assisted micro-blanking of pure copper foils

    Directory of Open Access Journals (Sweden)

    Wang Chunju

    2015-01-01

    Full Text Available The difficulties encountered during the manufacture of microparts are often associated with size effects relating to material, process and tooling. Utilizing acoustoplastic softening, achieved through a high-frequency vibration assisted micro-blanking process, was introduced to improve the surface finish in micro-blanking. A frequency of 1.0 kHz was chosen to activate the longitudinal vibration mode of the horn tip, using a piezoelectric actuator. A square hole with dimensions of 0.5 mm × 0.5 mm was made, successfully, from a commercial rolled T2 copper foil with 100 μm in thickness. It was found that the maximum blanking force could be reduced by 5% through utilizing the high-frequency vibration. Proportion of the smooth, burnished area in the cut cross-section increases with an increase of the plasticity to fracture, under the high-frequency vibration, which suggests that the vibration introduced is helpful for inhibiting evolution of the crack due to its acoustoplastic softening effect. During blanking, roughness of the burnished surface could be reduced by increasing the vibration amplitude of the punch, which played a role as surface polishing. The results obtained suggest that the high-frequency vibration can be adopted in micro-blanking in order to improve quality of the microparts.

  5. Effects of vibration frequency on vibration-assisted nano-scratch process of mono-crystalline copper via molecular dynamics simulation

    Directory of Open Access Journals (Sweden)

    Bo Zhu

    2016-03-01

    Full Text Available It has always been a critical issue to understand the material removal behavior of Vibration-Assisted Machining (VAM, especially on atomic level. To find out the effects of vibration frequency on material removal response, a three-dimensional molecular dynamics (MD model has been established in this research to investigate the effects of scratched groove, crystal defects on the surface quality, comparing with the Von Mises shear strain and tangential force in simulations during nano-scratching process. Comparisons are made among the results of simulations from different vibration frequency with the same scratching feed, depth, amplitude and crystal orientation. Copper potential in this simulation is Embedded-Atom Method (EAM potential. Interaction between copper and carbon atoms is Morse potential. Simulational results show that higher frequency can make groove smoother. Simulation with high frequency creates more dislocations to improve the machinability of copper specimen. The changing frequency does not have evident effects on Von Mises shear strain. Higher frequency can decrease the tangential force to reduce the consumption of cutting energy and tool wear. In conclusion, higher vibration frequency in VAM on mono-crystalline copper has positive effects on surface finish, machinablility and tool wear reduction.

  6. Effects of vibration frequency on vibration-assisted nano-scratch process of mono-crystalline copper via molecular dynamics simulation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Bo; Zhao, Hongwei, E-mail: hwzhao@jlu.edu.cn, E-mail: khl69@163.com; Zhao, Dan; Zhang, Peng; Yang, Yihan; Han, Lei [School of Mechanical Science and Engineering, Jilin University, 5988 Renmin Street, Changchun, Jilin 130025 (China); Kui, Hailin, E-mail: hwzhao@jlu.edu.cn, E-mail: khl69@163.com [School of Transportation, Jilin University, 5988 Renmin Street, Changchun, Jilin 130025 (China)

    2016-03-15

    It has always been a critical issue to understand the material removal behavior of Vibration-Assisted Machining (VAM), especially on atomic level. To find out the effects of vibration frequency on material removal response, a three-dimensional molecular dynamics (MD) model has been established in this research to investigate the effects of scratched groove, crystal defects on the surface quality, comparing with the Von Mises shear strain and tangential force in simulations during nano-scratching process. Comparisons are made among the results of simulations from different vibration frequency with the same scratching feed, depth, amplitude and crystal orientation. Copper potential in this simulation is Embedded-Atom Method (EAM) potential. Interaction between copper and carbon atoms is Morse potential. Simulational results show that higher frequency can make groove smoother. Simulation with high frequency creates more dislocations to improve the machinability of copper specimen. The changing frequency does not have evident effects on Von Mises shear strain. Higher frequency can decrease the tangential force to reduce the consumption of cutting energy and tool wear. In conclusion, higher vibration frequency in VAM on mono-crystalline copper has positive effects on surface finish, machinablility and tool wear reduction.

  7. First-principles studies of PETN molecular crystal vibrational frequencies under high pressure

    Science.gov (United States)

    Perger, Warren; Zhao, Jijun

    2005-07-01

    The vibrational frequencies of the PETN molecular crystal were calculated using the first-principles CRYSTAL03 program which employs an all-electron LCAO approach and calculates analytic first derivatives of the total energy with respect to atomic displacements. Numerical second derivatives were used to enable calculation of the vibrational frequencies at ambient pressure and under various states of compression. Three different density functionals, B3LYP, PW91, and X3LYP were used to examine the effect of the exchange-correlation functional on the vibrational frequencies. The pressure-induced shift of the vibrational frequencies will be presented and compared with experiment. The average deviation with experimental results is shown to be on the order of 2-3%, depending on the functional used.

  8. A low-frequency vibration energy harvester based on diamagnetic levitation

    Science.gov (United States)

    Kono, Yuta; Masuda, Arata; Yuan, Fuh-Gwo

    2017-04-01

    This article presents 3-degree-of-freedom theoretical modeling and analysis of a low-frequency vibration energy harvester based on diamagnetic levitation. In recent years, although much attention has been placed on vibration energy harvesting technologies, few harvesters still can operate efficiently at extremely low frequencies in spite of large potential demand in the field of structural health monitoring and wearable applications. As one of the earliest works, Liu, Yuan and Palagummi proposed vertical and horizontal diamagnetic levitation systems as vibration energy harvesters with low resonant frequencies. This study aims to pursue further improvement along this direction, in terms of expanding maximum amplitude and enhancing the flexibility of the operation direction for broader application fields by introducing a new topology of the levitation system.

  9. Low frequency vibrations disrupt left-right patterning in the Xenopus embryo.

    Directory of Open Access Journals (Sweden)

    Laura N Vandenberg

    Full Text Available The development of consistent left-right (LR asymmetry across phyla is a fascinating question in biology. While many pharmacological and molecular approaches have been used to explore molecular mechanisms, it has proven difficult to exert precise temporal control over functional perturbations. Here, we took advantage of acoustical vibration to disrupt LR patterning in Xenopus embryos during tightly-circumscribed periods of development. Exposure to several low frequencies induced specific randomization of three internal organs (heterotaxia. Investigating one frequency (7 Hz, we found two discrete periods of sensitivity to vibration; during the first period, vibration affected the same LR pathway as nocodazole, while during the second period, vibration affected the integrity of the epithelial barrier; both are required for normal LR patterning. Our results indicate that low frequency vibrations disrupt two steps in the early LR pathway: the orientation of the LR axis with the other two axes, and the amplification/restriction of downstream LR signals to asymmetric organs.

  10. The low frequency 2D vibration sensor based on flat coil element

    Energy Technology Data Exchange (ETDEWEB)

    Djamal, Mitra; Sanjaya, Edi; Islahudin; Ramli [Department of Physics, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40116 (Indonesia); Department of Physics, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40116 (Indonesia) and Department of Physics, UIN Syarif Hidayatullah, Jl. Ir.H. Djuanda 95 Ciputat 15412 (Indonesia); MTs NW Nurul Iman Kembang Kerang, Jl. Raya Mataram - Lb.Lombok, NTB (Indonesia); Department of Physics, Institut Teknologi Bandung, Jl. Ganesa 10 Bandung 40116 (Indonesia) and Department of Physics,Universitas Negeri Padang, Jl. Prof. Hamka, Padang 25132 (Indonesia)

    2012-06-20

    Vibration like an earthquake is a phenomenon of physics. The characteristics of these vibrations can be used as an early warning system so as to reduce the loss or damage caused by earthquakes. In this paper, we introduced a new type of low frequency 2D vibration sensor based on flat coil element that we have developed. Its working principle is based on position change of a seismic mass that put in front of a flat coil element. The flat coil is a part of a LC oscillator; therefore, the change of seismic mass position will change its resonance frequency. The results of measurements of low frequency vibration sensor in the direction of the x axis and y axis gives the frequency range between 0.2 to 1.0 Hz.

  11. Mode shape and natural frequency identification for seismic analysis from background vibration

    International Nuclear Information System (INIS)

    Bhan, S.; Wozniak, Z.

    1986-02-01

    The feasibility of calculating natural frequencies and mode shapes of major equipment in a CANDU reactor from the measurements of their response to background excitation has been studied. A review of vibration data measured at various locations in CANDU plants shows that structures responded to a combination of random and harmonic background excitation. Amplitude of measured vibration is sufficient to allow meaningful data analysis. Frequency content in the 0 to 50-Hz range, which is of interest for earthquake response, is present in some of the vibration measurements studied. Spectral techniques have been developed for determining the response function of structures from measured vibration response to background excitation. The natural frequencies and mode shapes are then evaluated graphically from the frequency function plots. The methodology has been tested on a simple cantilever beam with known natural frequencies and mode shapes. The comparison between the theoretical and the computed natural frequencies and mode shapes is good for the lower modes. However, better curve-fitting techniques will be required in future, especially for higher modes. Readily available equipment necessary for the measurement of background vibration in a CANDU plant (which is commercially available) has been identified. An experimental program has been proposed to verify the methodology developed in this study. Recommendations are also made to study methods to improve the accuracy of the mode shape and natural frequency prediction

  12. Effect of Low Frequency Burner Vibrations on the Characteristics of Jet Diffusion Flames

    Directory of Open Access Journals (Sweden)

    C. Kanthasamy

    2012-03-01

    Full Text Available Mechanical vibrations introduced in diffusion flame burners significantly affect the flame characteristics. In this experimental study, the effects of axial vibrations on the characteristics of laminar diffusion flames are investigated systematically. The effect of the frequency and amplitude of the vibrations on the flame height oscillations and flame stability is brought out. The amplitude of flame height oscillations is found to increase with increase in both frequency and amplitude of burner vibrations. Vibrations are shown to enhance stability of diffusion flames. Although flame lifts-off sooner with vibrations, stability of the flame increases.

  13. High frequency vibration analysis by the complex envelope vectorization.

    Science.gov (United States)

    Giannini, O; Carcaterra, A; Sestieri, A

    2007-06-01

    The complex envelope displacement analysis (CEDA) is a procedure to solve high frequency vibration and vibro-acoustic problems, providing the envelope of the physical solution. CEDA is based on a variable transformation mapping the high frequency oscillations into signals of low frequency content and has been successfully applied to one-dimensional systems. However, the extension to plates and vibro-acoustic fields met serious difficulties so that a general revision of the theory was carried out, leading finally to a new method, the complex envelope vectorization (CEV). In this paper the CEV method is described, underlying merits and limits of the procedure, and a set of applications to vibration and vibro-acoustic problems of increasing complexity are presented.

  14. Examining the impact of harmonic correlation on vibrational frequencies calculated in localized coordinates

    Energy Technology Data Exchange (ETDEWEB)

    Hanson-Heine, Magnus W. D., E-mail: magnus.hansonheine@nottingham.ac.uk [School of Chemistry, University of Nottingham, University Park, Nottingham NG7 2RD (United Kingdom)

    2015-10-28

    Carefully choosing a set of optimized coordinates for performing vibrational frequency calculations can significantly reduce the anharmonic correlation energy from the self-consistent field treatment of molecular vibrations. However, moving away from normal coordinates also introduces an additional source of correlation energy arising from mode-coupling at the harmonic level. The impact of this new component of the vibrational energy is examined for a range of molecules, and a method is proposed for correcting the resulting self-consistent field frequencies by adding the full coupling energy from connected pairs of harmonic and pseudoharmonic modes, termed vibrational self-consistent field (harmonic correlation). This approach is found to lift the vibrational degeneracies arising from coordinate optimization and provides better agreement with experimental and benchmark frequencies than uncorrected vibrational self-consistent field theory without relying on traditional correlated methods.

  15. Vibration-rotation band intensities in the IR spectra of polyatomic molecules

    International Nuclear Information System (INIS)

    El'kin, M.D.; Kosterina, E.K.; Berezin

    1995-01-01

    Using the curvilinear vibrational coordinates for a nuclear subsystem, expressions for the effective dipole-moment operators are derived in order to analyze the vibrational-rotational transitions in the IR spectra of polyatomic rigid molecules. The explicit expressions obtained for the intensities of hot bands allow one to estimate the influence of the vibration-rotation interaction within the framework of the adopted molecular-vibration model. The suggested method is shown to be suitable for Raman spectra analysis. 12 refs

  16. Frequency Tuning of Vibration Absorber Using Topology Optimization

    Science.gov (United States)

    Harel, Swapnil Subhash

    A tuned mass absorber is a system for reducing the amplitude in one oscillator by coupling it to a second oscillator. If tuned correctly, the maximum amplitude of the first oscillator in response to a periodic driver will be lowered, and much of the vibration will be 'transferred' to the second oscillator. The tuned vibration absorber (TVA) has been utilized for vibration control purposes in many sectors of Civil/Automotive/Aerospace Engineering for many decades since its inception. Time and again we come across a situation in which a vibratory system is required to run near resonance. In the past, approaches have been made to design such auxiliary spring mass tuned absorbers for the safety of the structures. This research focuses on the development and optimization of continuously tuned mass absorbers as a substitute to the discretely tuned mass absorbers (spring- mass system). After conducting the study of structural behavior, the boundary condition and frequency to which the absorber is to be tuned are determined. The Modal analysis approach is used to determine mode shapes and frequencies. The absorber is designed and optimized using the topology optimization tool, which simultaneously designs, optimizes and tunes the absorber to the desired frequency. The tuned, optimized absorber, after post processing, is attached to the target structure. The number of the absorbers are increased to amplify bandwidth and thereby upgrade the safety of structure for a wide range of frequency. The frequency response analysis is carried out using various combinations of structure and number of absorber cell.

  17. Low frequency torsional vibration gaps in the shaft with locally resonant structures

    International Nuclear Information System (INIS)

    Yu Dianlong; Liu Yaozong; Wang Gang; Cai Li; Qiu Jing

    2006-01-01

    The propagation of torsional wave in the shaft with periodically attached local resonators is studied with the transfer matrix theory and the finite element method. The analytical dispersion relation and the complex band structure of such a structure is presented for the first time, which indicates the existence of low frequency gaps. The effect of shaft material on the vibration attenuation in band gap is investigated. The frequency response function of the shaft with finite periodic locally resonant oscillators is simulated with finite element method, which shows large vibration attenuation in the frequency range of the gap as expected. The low frequency torsional gap in shafts provides a new idea for vibration control

  18. High-precision and low-cost vibration generator for low-frequency calibration system

    Science.gov (United States)

    Li, Rui-Jun; Lei, Ying-Jun; Zhang, Lian-Sheng; Chang, Zhen-Xin; Fan, Kuang-Chao; Cheng, Zhen-Ying; Hu, Peng-Hao

    2018-03-01

    Low-frequency vibration is one of the harmful factors that affect the accuracy of micro-/nano-measuring machines because its amplitude is significantly small and it is very difficult to avoid. In this paper, a low-cost and high-precision vibration generator was developed to calibrate an optical accelerometer, which is self-designed to detect low-frequency vibration. A piezoelectric actuator is used as vibration exciter, a leaf spring made of beryllium copper is used as an elastic component, and a high-resolution, low-thermal-drift eddy current sensor is applied to investigate the vibrator’s performance. Experimental results demonstrate that the vibration generator can achieve steady output displacement with frequency range from 0.6 Hz to 50 Hz, an analytical displacement resolution of 3.1 nm and an acceleration range from 3.72 mm s-2 to 1935.41 mm s-2 with a relative standard deviation less than 1.79%. The effectiveness of the high-precision and low-cost vibration generator was verified by calibrating our optical accelerometer.

  19. Comparative analysis of internal friction and natural frequency measured by free decay and forced vibration

    International Nuclear Information System (INIS)

    Wang, Y. Z.; Ding, X. D.; Xiong, X. M.; Zhang, J. X.

    2007-01-01

    Relations between various values of the internal friction (tgδ, Q -1 , Q -1* , and Λ/π) measured by free decay and forced vibration are analyzed systemically based on a fundamental mechanical model in this paper. Additionally, relations between various natural frequencies, such as vibration frequency of free decay ω FD , displacement-resonant frequency of forced vibration ω d , and velocity-resonant frequency of forced vibration ω 0 are calculated. Moreover, measurement of natural frequencies of a copper specimen of 99.9% purity has been made to demonstrate the relation between the measured natural frequencies of the system by forced vibration and free decay. These results are of importance for not only more accurate measurement of the elastic modulus of materials but also the data conversion between different internal friction measurements

  20. Frequency identification of vibration signals using video camera image data.

    Science.gov (United States)

    Jeng, Yih-Nen; Wu, Chia-Hung

    2012-10-16

    This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC) can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system.

  1. Frequency Identification of Vibration Signals Using Video Camera Image Data

    Directory of Open Access Journals (Sweden)

    Chia-Hung Wu

    2012-10-01

    Full Text Available This study showed that an image data acquisition system connecting a high-speed camera or webcam to a notebook or personal computer (PC can precisely capture most dominant modes of vibration signal, but may involve the non-physical modes induced by the insufficient frame rates. Using a simple model, frequencies of these modes are properly predicted and excluded. Two experimental designs, which involve using an LED light source and a vibration exciter, are proposed to demonstrate the performance. First, the original gray-level resolution of a video camera from, for instance, 0 to 256 levels, was enhanced by summing gray-level data of all pixels in a small region around the point of interest. The image signal was further enhanced by attaching a white paper sheet marked with a black line on the surface of the vibration system in operation to increase the gray-level resolution. Experimental results showed that the Prosilica CV640C CMOS high-speed camera has the critical frequency of inducing the false mode at 60 Hz, whereas that of the webcam is 7.8 Hz. Several factors were proven to have the effect of partially suppressing the non-physical modes, but they cannot eliminate them completely. Two examples, the prominent vibration modes of which are less than the associated critical frequencies, are examined to demonstrate the performances of the proposed systems. In general, the experimental data show that the non-contact type image data acquisition systems are potential tools for collecting the low-frequency vibration signal of a system.

  2. Contact area affects frequency-dependent responses to vibration in the peripheral vascular and sensorineural systems.

    Science.gov (United States)

    Krajnak, Kristine; Miller, G R; Waugh, Stacey

    2018-01-01

    Repetitive exposure to hand-transmitted vibration is associated with development of peripheral vascular and sensorineural dysfunctions. These disorders and symptoms associated with it are referred to as hand-arm vibration syndrome (HAVS). Although the symptoms of the disorder have been well characterized, the etiology and contribution of various exposure factors to development of the dysfunctions are not well understood. Previous studies performed using a rat-tail model of vibration demonstrated that vascular and peripheral nervous system adverse effects of vibration are frequency-dependent, with vibration frequencies at or near the resonant frequency producing the most severe injury. However, in these investigations, the amplitude of the exposed tissue was greater than amplitude typically noted in human fingers. To determine how contact with vibrating source and amplitude of the biodynamic response of the tissue affects the risk of injury occurring, this study compared the influence of frequency using different levels of restraint to assess how maintaining contact of the tail with vibrating source affects the transmission of vibration. Data demonstrated that for the most part, increasing the contact of the tail with the platform by restraining it with additional straps resulted in an enhancement in transmission of vibration signal and elevation in factors associated with vascular and peripheral nerve injury. In addition, there were also frequency-dependent effects, with exposure at 250 Hz generating greater effects than vibration at 62.5 Hz. These observations are consistent with studies in humans demonstrating that greater contact and exposure to frequencies near the resonant frequency pose the highest risk for generating peripheral vascular and sensorineural dysfunction.

  3. The effects of vibration-reducing gloves on finger vibration

    Science.gov (United States)

    Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

    2015-01-01

    Vibration-reducing (VR) gloves have been used to reduce the hand-transmitted vibration exposures from machines and powered hand tools but their effectiveness remains unclear, especially for finger protection. The objectives of this study are to determine whether VR gloves can attenuate the vibration transmitted to the fingers and to enhance the understanding of the mechanisms of how these gloves work. Seven adult male subjects participated in the experiment. The fixed factors evaluated include hand force (four levels), glove condition (gel-filled, air bladder, no gloves), and location of the finger vibration measurement. A 3-D laser vibrometer was used to measure the vibrations on the fingers with and without wearing a glove on a 3-D hand-arm vibration test system. This study finds that the effect of VR gloves on the finger vibration depends on not only the gloves but also their influence on the distribution of the finger contact stiffness and the grip effort. As a result, the gloves increase the vibration in the fingertip area but marginally reduce the vibration in the proximal area at some frequencies below 100 Hz. On average, the gloves reduce the vibration of the entire fingers by less than 3% at frequencies below 80 Hz but increase at frequencies from 80 to 400 Hz. At higher frequencies, the gel-filled glove is more effective at reducing the finger vibration than the air bladder-filled glove. The implications of these findings are discussed. Relevance to industry Prolonged, intensive exposure to hand-transmitted vibration can cause hand-arm vibration syndrome. Vibration-reducing gloves have been used as an alternative approach to reduce the vibration exposure. However, their effectiveness for reducing finger-transmitted vibrations remains unclear. This study enhanced the understanding of the glove effects on finger vibration and provided useful information on the effectiveness of typical VR gloves at reducing the vibration transmitted to the fingers. The new

  4. Low frequency vibrations induce malformations in two aquatic species in a frequency-, waveform-, and direction-specific manner.

    Directory of Open Access Journals (Sweden)

    Laura N Vandenberg

    Full Text Available Environmental toxicants such as industrial wastes, air particulates from machinery and transportation vehicles, and pesticide run-offs, as well as many chemicals, have been widely studied for their effects on human and wildlife populations. Yet other potentially harmful environmental pollutants such as electromagnetic pulses, noise and vibrations have remained incompletely understood. Because developing embryos undergo complex morphological changes that can be affected detrimentally by alterations in physical forces, they may be particularly susceptible to exposure to these types of pollutants. We investigated the effects of low frequency vibrations on early embryonic development of two aquatic species, Xenopus laevis (frogs and Danio rerio (zebrafish, specifically focusing on the effects of varying frequencies, waveforms, and applied direction. We observed treatment-specific effects on the incidence of neural tube defects, left-right patterning defects and abnormal tail morphogenesis in Xenopus tadpoles. Additionally, we found that low frequency vibrations altered left-right patterning and tail morphogenesis, but did not induce neural tube defects, in zebrafish. The results of this study support the conclusion that low frequency vibrations are toxic to aquatic vertebrates, with detrimental effects observed in two important model species with very different embryonic architectures.

  5. High frequency vibration characteristics of electric wheel system under in-wheel motor torque ripple

    Science.gov (United States)

    Mao, Yu; Zuo, Shuguang; Wu, Xudong; Duan, Xianglei

    2017-07-01

    With the introduction of in-wheel motor, the electric wheel system encounters new vibration problems brought by motor torque ripple excitation. In order to analyze new vibration characteristics of electric wheel system, torque ripple of in-wheel motor based on motor module and vector control system is primarily analyzed, and frequency/order features of the torque ripple are discussed. Then quarter vehicle-electric wheel system (QV-EWS) dynamics model based on the rigid ring tire assumption is established and the main parameters of the model are identified according to tire free modal test. Modal characteristics of the model are further analyzed. The analysis indicates that torque excitation of in-wheel motor is prone to arouse horizontal vibration, in which in-phase rotational, anti-phase rotational and horizontal translational modes of electric wheel system mainly participate. Based on the model, vibration responses of the QV-EWS under torque ripple are simulated. The results show that unlike vertical low frequency (lower than 20 Hz) vibration excited by road roughness, broadband torque ripple will arouse horizontal high frequency (50-100 Hz) vibration of electric wheel system due to participation of the three aforementioned modes. To verify the theoretical analysis, the bench experiment of electric wheel system is conducted and vibration responses are acquired. The experiment demonstrates the high frequency vibration phenomenon of electric wheel system and the measured order features as well as main resonant frequencies agree with simulation results. Through theoretical modeling, analysis and experiments this paper reveals and explains the high frequency vibration characteristics of electric wheel system, providing references for the dynamic analysis, optimal design of QV-EWS.

  6. Molecular Geometry And Vibrational Spectra of 2'-chloroacetanilide

    International Nuclear Information System (INIS)

    Gokce, H.

    2008-01-01

    The molecular structure, vibrational frequencies and the corresponding vibrational assingments of 2'-chloroacetanilide in the ground state have been calculated by using Hartree-Fock (HF) and Density Functional Theory (DFT/B3LYP) methods with 6-311++G(d,p) basis set. The obtained vibrational frequencies and optimized geometric parameters (bond lenghts and angles) are in very good agreement with the experimental data. The comparison of the observed and calculated vibrational frequencies assignments of 2'-chloroacetanilide exhibit that the scaled DFT/B3LYP method is superior to be scaled HF method. Furthermore the calculated Infrared and Raman intensities are also reported

  7. Characteristics in Molecular Vibrational Frequency Patterns between Agonists and Antagonists of Histamine Receptors

    Directory of Open Access Journals (Sweden)

    S. June Oh

    2012-06-01

    Full Text Available To learn the differences between the structure-activity relationship and molecular vibration-activity relationship in the ligand-receptor interaction of the histamine receptor, 47 ligands of the histamine receptor were analyzed by structural similarity and molecular vibrational frequency patterns. The radial tree that was produced by clustering analysis of molecular vibrational frequency patterns shows its potential for the functional classification of histamine receptor ligands.

  8. Flextensional fiber Bragg grating-based accelerometer for low frequency vibration measurement

    Institute of Scientific and Technical Information of China (English)

    Jinghua Zhang; Xueguang Qiao; Manli Hu; Zhongyao Feng; Hong Gao; Yang Yang; Rui Zhou

    2011-01-01

    @@ The intelligent structural health monitoring method,which uses a fiber Bragg grating(FBG)sensor,is a new approach in the field of civil engineering.However,it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements.In this letter,a flextensional FBG-based accelerometer is proposed and demonstrated.The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz,with a high sensitivity of 410.7 pm/g.In addition,it has a broad and flat response over low frequencies ranging from 1 to 10 Hz.The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications.Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer.These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.%The intelligent structural health monitoring method, which uses a fiber Bragg grating {FBG} sensor, ie a new approach in the field of civil engineering. However, it lacks a reliable FBG-based accelerometer for taking structural low frequency vibration measurements. In this letter, a flextensional FBG-based accelerometer is proposed and demonstrated. The experimental results indicate that the natural frequency of the developed accelerometer is 16.7 Hz, with a high sensitivity of 410.7 pm/g. In addition, it has a broad and flat response over low frequencies ranging from 1 to 10 Hz. The natural frequency and sensitivity of the accelerometer can be tuned by adding mass to tailor the sensor performance to specific applications. Experimental results are presented to demonstrate the good performance of the proposed FBG-based accelerometer. These results show that the proposed accelerometer is satisfactory for low frequency vibration measurements.

  9. Broadband electromagnetic power harvester from vibrations via frequency conversion by impact oscillations

    International Nuclear Information System (INIS)

    Yuksek, N. S.; Almasri, M.; Feng, Z. C.

    2014-01-01

    In this paper, we propose an electromagnetic power harvester that uses a transformative multi-impact approach to achieve a wide bandwidth response from low frequency vibration sources through frequency-up conversion. The device consists of a pick-up coil, fixed at the free edge of a cantilever beam with high resonant frequency, and two cantilever beams with low excitation frequencies, each with an impact mass attached at its free edge. One of the two cantilevers is designed to resonate at 25 Hz, while the other resonates at 50 Hz within the range of ambient vibration frequency. When the device is subjected to a low frequency vibration, the two low-frequency cantilevers responded by vibrating at low frequencies, and thus their thick metallic masses made impacts with the high resonance frequency cantilever repeatedly at two locations. This has caused it along with the pick-up coil to oscillate, relative to the permanent magnet, with decaying amplitude at its resonance frequency, and results in a wide bandwidth response from 10 to 63 Hz at 2 g. A wide bandwidth response between 10–51 Hz and 10–58 Hz at acceleration values of 0.5 g and 2 g, respectively, were achieved by adjusting the impact cantilever frequencies closer to each other (25 Hz and 45 Hz). A maximum output power of 85 μW was achieved at 5 g at 30 Hz across a load resistor, 2.68 Ω.

  10. An analytical study of the effects of transverse shear deformation and anisotropy on natural vibration frequencies of laminated cylinders

    Science.gov (United States)

    Jegley, Dawn C.

    1988-01-01

    Natural vibration frequencies of orthotropic and anisotropic simply supported right circular cylinders are predicted using a higher-order transverse-shear deformation theory. A comparison of natural vibration frequencies predicted by first-order transverse-shear deformation theory and the higher-order theory shows that an additional allowance for transverse shear deformation has a negligible effect on the lowest predicted natural vibration frequencies of laminated cylinders but significantly reduces the higher natural vibration frequencies. A parametric study of the effects of ply orientation on the natural vibration frequencies of laminated cylinders indicates that while stacking sequence affects natural vibration frequencies, cylinder geometry is more important in predicting transverse-shear deformation effects. Interaction curves for cylinders subjected to axial compressive loadings and low natural vibration frequencies indicate that transverse shearing effects are less important in predicting low natural vibration frequencies than in predicting axial compressive buckling loads. The effects of anisotropy are more important than the effects of transverse shear deformation for most strongly anisotropic laminated cylinders in predicting natural vibration frequencies. However, transverse-shear deformation effects are important in predicting high natural vibration frequencies of thick-walled laminated cylinders. Neglecting either anisotropic effects or transverse-shear deformation effects leads to non-conservative errors in predicted natural vibration frequencies.

  11. Development of a distributed polarization-OTDR to measure two vibrations with the same frequency

    Science.gov (United States)

    Pan, Yun; Wang, Feng; Wang, Xiangchuan; Zhang, Mingjiang; Zhou, Ling; Sun, Zhenqing; Zhang, Xuping

    2015-08-01

    A polarization optical time-domain reflectometer (POTDR) can distributedly measure the vibration of fiber by detecting the vibration induced polarization variation only with a polarization analyzer. It has great potential in the monitoring of the border intrusion, structural healthy, anti-stealing of pipeline and so on, because of its simple configuration, fast response speed and distributed measuring ability. However, it is difficult to distinguish two vibrations with the same frequency for POTDR because the signal induced by the first vibration would bury the other vibration induced signal. This paper proposes a simple method to resolve this problem in POTDR by analyzing the phase of the vibration induced signal. The effectiveness of this method in distinguishing two vibrations with the same frequency for POTDR is proved by simulation.

  12. A Solvatochromic Model Calibrates Nitriles’ Vibrational Frequencies to Electrostatic Fields

    Science.gov (United States)

    Bagchi, Sayan; Fried, Stephen D.; Boxer, Steven G.

    2012-01-01

    Electrostatic interactions provide a primary connection between a protein’s three-dimensional structure and its function. Infrared (IR) probes are useful because vibrational frequencies of certain chemical groups, such as nitriles, are linearly sensitive to local electrostatic field, and can serve as a molecular electric field meter. IR spectroscopy has been used to study electrostatic changes or fluctuations in proteins, but measured peak frequencies have not been previously mapped to total electric fields, because of the absence of a field-frequency calibration and the complication of local chemical effects such as H-bonds. We report a solvatochromic model that provides a means to assess the H-bonding status of aromatic nitrile vibrational probes, and calibrates their vibrational frequencies to electrostatic field. The analysis involves correlations between the nitrile’s IR frequency and its 13C chemical shift, whose observation is facilitated by a robust method for introducing isotopes into aromatic nitriles. The method is tested on the model protein Ribonuclease S (RNase S) containing a labeled p-CN-Phe near the active site. Comparison of the measurements in RNase S against solvatochromic data gives an estimate of the average total electrostatic field at this location. The value determined agrees quantitatively with MD simulations, suggesting broader potential for the use of IR probes in the study of protein electrostatics. PMID:22694663

  13. Electromagnetic energy harvesting from vibrations of multiple frequencies

    International Nuclear Information System (INIS)

    Yang Bin; Lee Chengkuo; Xie Jin; Han He, Johnny; Kotlanka, Rama Krishna; Feng Hanhua; Xiang Wenfeng; Low, Siew Ping

    2009-01-01

    A novel multi-frequency energy harvester has been designed and fabricated, which consists of three permanent magnets, three sets of two-layer copper coils and a supported beam of acrylic, while these coils are made of thin fire resistant 4 (FR4) substrates using a standard printed circuit board. The energy under the first, second and third resonant modes can be harvested, corresponding to the resonant frequencies of 369 Hz, 938 Hz and 1184 Hz, respectively. The maximum output voltage and power of the first and second vibration modes are 1.38 mV, 0.6 µW and 3.2 mV, 3.2 µW for a 14 µm exciting vibration amplitude and a 0.4 mm gap between the magnet and coils, respectively. The feasibility study results are in good agreement with the theoretical calculations and show promising application potentials

  14. Sum frequency generation for surface vibrational spectroscopy

    International Nuclear Information System (INIS)

    Hunt, J.H.; Guyot-Sionnest, P.; Shen, Y.R.

    1987-01-01

    Surface vibrational spectroscopy is one of the best means for characterizing molecular adsorbates. For this reason, many techniques have been developed in the past. However, most of them suffer from poor sensitivity, low spectral and temporal resolution, and applications limited to vacuum solid interfaces. Recently, the second harmonic generation (SHG) technique was proved repeatedly to be a simple but versatile surface probe. It is highly sensitive and surface specific; it is also capable of achieving high temporal, spatial, and spectral resolution. Being an optical technique, it can be applied to any interface accessible by light. The only serious drawback is its lack of molecular selectivity. An obvious remedy is the extension of the technique to IR-visible sum frequency generation (SFG). Surface vibrational spectroscopy with submonolayer sensitivity is then possible using SFG with the help of a tunable IR laser. The authors report here an SFG measurement of the C-H stretch vibration of monolayers of molecules at air-solid and air-liquid interfaces

  15. Structure-borne sound structural vibrations and sound radiation at audio frequencies

    CERN Document Server

    Cremer, L; Petersson, Björn AT

    2005-01-01

    Structure-Borne Sound"" is a thorough introduction to structural vibrations with emphasis on audio frequencies and the associated radiation of sound. The book presents in-depth discussions of fundamental principles and basic problems, in order to enable the reader to understand and solve his own problems. It includes chapters dealing with measurement and generation of vibrations and sound, various types of structural wave motion, structural damping and its effects, impedances and vibration responses of the important types of structures, as well as with attenuation of vibrations, and sound radi

  16. The Influence of Various Vibration Frequency on Barium Sulfate Scale Formation Of Vibrated Piping System In The Presence Citric Acid

    Science.gov (United States)

    Karaman, N.; Mangestiyono, W.; Muryanto, S.; Jamari, J.; Bayuseno, A. P.

    2018-01-01

    In this paper, the influence of vibrated piping system for BaSO4 scale formation was investigated. The vibration frequency and presence of citric acid were independent variables determining the kinetics, mass deposit and polymorph of the crystals. Correspondingly, induction time and mass of scale were obtained during the experiments. The crystalline scale was observed by scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) to investigate the morphology and the phase mineral deposits, respectively. This effect indicated that the increase in vibration frequency promoted the increased deposition rate, while the pure barite with a plate-like morphology was produced in the experiments.

  17. Resonant frequency function of thickness-shear vibrations of rectangular crystal plates.

    Science.gov (United States)

    Wang, Ji; Yang, Lijun; Pan, Qiaoqiao; Chao, Min-Chiang; Du, Jianke

    2011-05-01

    The resonant frequencies of thickness-shear vibrations of quartz crystal plates in rectangular and circular shapes are always required in the design and manufacturing of quartz crystal resonators. As the size of quartz crystal resonators shrinks, for rectangular plates we must consider effects of both length and width for the precise calculation of resonant frequency. Starting from the three-dimensional equations of wave propagation in finite crystal plates and the general expression of vibration modes, we obtained the relations between frequency and wavenumbers. By satisfying the major boundary conditions of the dominant thickness-shear mode, three wavenumber solutions are obtained and the frequency equation is constructed. It is shown the resonant frequency of thickness-shear mode is a second-order polynomial of aspect ratios. This conforms to known results in the simplest form and is applicable to further analytical and experimental studies of the frequency equation of quartz crystal resonators.

  18. Theoretical Investigation of Vibrational Frequencies for Tetrabromopalladate (II Ion

    Directory of Open Access Journals (Sweden)

    Metin Bilge

    2010-11-01

    Full Text Available The normal mode frequencies and corresponding vibrational assignments of tetrabromopalladate (II ion ([Pd(Br4]2- have been theoretically examined by means of standard quantum chemical technique. All normal modes have been successfully assigned utilizing the D4h symmetry of [Pd(Br4]2-. Calculation has been performed at the Becke-3-Lee-Yang-Parr (B3LYP density functional method using the Lanl2dz basis set. Infrared intensities and Raman activities have also been calculated and reported. Theoretical results have been successfully compared against available experimental data. Key words: [Pd(Br4]2-, DFT, vibrational assignment, normal mode frequency, Lanl2dz Tetrabromopaladyum (II İyonunun Titreşim Frekanslarının Teorik Olarak İncelenmesi Tetrabromopaladyum (II iyonunun ([Pd(Br4]2- normal mod frekansları ve bunlara karşılık gelen titreşim işaretlemeleri standart kuantum kimyasal teknik yardımıyla teorik olarak incelenmektedir. Tüm normal modlar [Pd(Br4]2- iyonunun D4h nokta grubu kullanılarak başarılı bir şekilde işaretlenmiştir. Hesaplama Lanl2dz baz seti kullanılarak B3LYP (Becke-3-Lee-Yang-Parr yoğunluk fonksiyonel metoduyla gerçekleştirilmiş ve infrared intensiteleri ile Raman aktiviteleri de hesaplanmıştır. Teorik sonuçlar mevcut deneysel değerler ile başarılı bir şekilde karşılaştırılmaktadır. Anahtar kelimeler: [Pd(Br4]2-, DFT, titreşim işaretlemesi, normal mod frekansı, Lanl2dz

  19. Experimental investigation on low-frequency vibration assisted micro-WEDM of Inconel 718

    Directory of Open Access Journals (Sweden)

    Deepak Rajendra Unune

    2017-02-01

    Full Text Available The micro-wire electric discharge machining (micro-WEDM has emerged as the popular micromachining processes for fabrication of micro-features. However, the low machining rate and poor surface finish are restricting wide applications of this process. Therefore, in this study, an attempt was made to improve machining rate of micro-WEDM with low-frequency workpiece vibration assistance. The gap voltage, capacitance, feed rate and vibrational frequency were chosen as control factors, whereas, the material removal rate (MRR and kerf width were selected as performance measures while fabricating microchannels in Inconel 718. It was observed that in micro-WEDM, the capacitance is the most significant factor affecting both MRR and kerf width. It was witnessed that the low-frequency workpiece vibration improves the performance of micro-WEDM by improving the MRR due to enhanced flushing conditions and reduced electrode-workpiece adhesion.

  20. Measuring frequency of one-dimensional vibration with video camera using electronic rolling shutter

    Science.gov (United States)

    Zhao, Yipeng; Liu, Jinyue; Guo, Shijie; Li, Tiejun

    2018-04-01

    Cameras offer a unique capability of collecting high density spatial data from a distant scene of interest. They can be employed as remote monitoring or inspection sensors to measure vibrating objects because of their commonplace availability, simplicity, and potentially low cost. A defect of vibrating measurement with the camera is to process the massive data generated by camera. In order to reduce the data collected from the camera, the camera using electronic rolling shutter (ERS) is applied to measure the frequency of one-dimensional vibration, whose frequency is much higher than the speed of the camera. Every row in the image captured by the ERS camera records the vibrating displacement at different times. Those displacements that form the vibration could be extracted by local analysis with sliding windows. This methodology is demonstrated on vibrating structures, a cantilever beam, and an air compressor to identify the validity of the proposed algorithm. Suggestions for applications of this methodology and challenges in real-world implementation are given at last.

  1. A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Kyung Ho; Kim, Young-Cheol [Department of System Dynamics, Korea Institute of Machinery and Materials, 156 Gajeongbuk-Ro, Yuseong-Gu, Daejeon 305-343 (Korea, Republic of); Kim, Jae Eun, E-mail: jekim@cu.ac.kr [School of Mechanical and Automotive Engineering, Catholic University of Daegu, 13-13 Hayang-Ro, Hayang-Eup, Gyeongsan-Si, Gyeongsangbuk-Do 712-702 (Korea, Republic of)

    2014-10-15

    While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm{sup 3}, which was designed for a target frequency of as low as 100 Hz.

  2. A small-form-factor piezoelectric vibration energy harvester using a resonant frequency-down conversion

    Directory of Open Access Journals (Sweden)

    Kyung Ho Sun

    2014-10-01

    Full Text Available While environmental vibrations are usually in the range of a few hundred Hertz, small-form-factor piezoelectric vibration energy harvesters will have higher resonant frequencies due to the structural size effect. To address this issue, we propose a resonant frequency-down conversion based on the theory of dynamic vibration absorber for the design of a small-form-factor piezoelectric vibration energy harvester. The proposed energy harvester consists of two frequency-tuned elastic components for lowering the first resonant frequency of an integrated system but is so configured that an energy harvesting beam component is inverted with respect to the other supporting beam component for a small form factor. Furthermore, in order to change the unwanted modal characteristic of small separation of resonant frequencies, as is the case with an inverted configuration, a proof mass on the supporting beam component is slightly shifted toward a second proof mass on the tip of the energy harvesting beam component. The proposed small-form-factor design capability was experimentally verified using a fabricated prototype with an occupation volume of 20 × 39 × 6.9 mm3, which was designed for a target frequency of as low as 100 Hz.

  3. An Analysis of the High Frequency Vibrations in Early Thematic Mapper Scenes

    Science.gov (United States)

    Kogut, J.; Larduinat, E.

    1985-01-01

    The motion of the mirrors in the thematic mapper (TM) and multispectral scanner (MSS) instruments, and the motion of other devices, such as the TDRSS antenna drive, and solar array drives onboard LANDSAT-4 cause vibrations to propagate through the spacecraft. These vibrations as well as nonlinearities in the scanning motion of the TM mirror can cause the TM detectors to point away from their nominal positions. Two computer programs, JITTER and SCDFT, were developed as part of the LANDSAT-D Assessment System (LAS), Products and Procedures Analysis (PAPA) program to evaluate the potential effect of high frequency vibrations on the final TM image. The maximum overlap and underlap which were observed for early TM scenes are well within specifications for the ground processing system. The cross scan and scan high frequency vibrations are also within the specifications cited for the flight system.

  4. Low-Magnitude, High-Frequency Vibration Fails to Accelerate Ligament Healing but Stimulates Collagen Synthesis in the Achilles Tendon.

    Science.gov (United States)

    Thompson, William R; Keller, Benjamin V; Davis, Matthew L; Dahners, Laurence E; Weinhold, Paul S

    2015-05-01

    Low-magnitude, high-frequency vibration accelerates fracture and wound healing and prevents disuse atrophy in musculoskeletal tissues. To investigate the role of low-magnitude, high-frequency vibration as a treatment to accelerate healing of an acute ligament injury and to examine gene expression in the intact Achilles tendon of the injured limb after low-magnitude, high-frequency vibration. Controlled laboratory study. Complete surgical transection of the medial collateral ligament (MCL) was performed in 32 Sprague-Dawley rats, divided into control and low-magnitude, high-frequency vibration groups. Low-magnitude, high-frequency vibration started on postoperative day 2, and rats received vibration for 30 minutes a day for 12 days. All rats were sacrificed 2 weeks after the operation, and their intact and injured MCLs were biomechanically tested or used for histological analysis. Intact Achilles tendons from the injured limb were evaluated for differences in gene expression. Mechanical testing revealed no differences in the ultimate tensile load or the structural stiffness between the control and vibration groups for either the injured or intact MCL. Vibration exposure increased gene expression of collagen 1 alpha (3-fold), interleukin 6 (7-fold), cyclooxygenase 2 (5-fold), and bone morphogenetic protein 12 (4-fold) in the intact Achilles tendon when compared with control tendons ( P frequency vibration treatment, significant enhancements in gene expression were observed in the intact Achilles tendon. These included collagen, several inflammatory cytokines, and growth factors critical for tendons. As low-magnitude, high-frequency vibration had no negative effects on ligament healing, vibration therapy may be a useful tool to accelerate healing of other tissues (bone) in multitrauma injuries without inhibiting ligament healing. Additionally, the enhanced gene expression in response to low-magnitude, high-frequency vibration in the intact Achilles tendon suggests the

  5. A wideband, frequency up-converting bounded vibration energy harvester for a low-frequency environment

    International Nuclear Information System (INIS)

    Ashraf, K; Md Khir, M H; Baharudin, Z; Dennis, J O

    2013-01-01

    This paper presents a bounded vibration energy harvester to effectively harvest energy from a wide band of low-frequency environmental vibrations ranging from 10 to 18 Hz. Rigid mechanical stoppers are used to confine the seismic mass movement within the elastic limits of the spring. Experimental results show the effectiveness of the proposed technique in increasing the efficiency of the energy harvester. When excited at a frequency of 10 Hz with a peak acceleration of 1 g, the harvester responds at a higher frequency of 20 Hz and gives a peak power of 2.68 mW and a peak to peak voltage of 2.62 V across a load of 220 Ω. The average power density of 65.74 μW cm −3 obtained at 10 Hz 1 g excitation monotonically increases with frequency up to 341.86 μW cm −3 at 18 Hz. An analytical model describing the nonlinear dynamics of the proposed harvester is also presented. A simple technique to estimate the energy losses during impact and thereof a method to incorporate these losses in the model are suggested. The presented model not only predicts the experimental voltage waveform and frequency response of the device with good similarity but also predicts the RMS voltage from the harvester for the whole range of operating frequencies with an RMS error of 5.2%. (paper)

  6. Vibrational investigation on FT-IR and FT-Raman spectra, IR intensity, Raman activity, peak resemblance, ideal estimation, standard deviation of computed frequencies analyses and electronic structure on 3-methyl-1,2-butadiene using HF and DFT (LSDA/B3LYP/B3PW91) calculations.

    Science.gov (United States)

    Ramalingam, S; Jayaprakash, A; Mohan, S; Karabacak, M

    2011-11-01

    FT-IR and FT-Raman (4000-100 cm(-1)) spectral measurements of 3-methyl-1,2-butadiene (3M12B) have been attempted in the present work. Ab-initio HF and DFT (LSDA/B3LYP/B3PW91) calculations have been performed giving energies, optimized structures, harmonic vibrational frequencies, IR intensities and Raman activities. Complete vibrational assignments on the observed spectra are made with vibrational frequencies obtained by HF and DFT (LSDA/B3LYP/B3PW91) at 6-31G(d,p) and 6-311G(d,p) basis sets. The results of the calculations have been used to simulate IR and Raman spectra for the molecule that showed good agreement with the observed spectra. The potential energy distribution (PED) corresponding to each of the observed frequencies are calculated which confirms the reliability and precision of the assignment and analysis of the vibrational fundamentals modes. The oscillation of vibrational frequencies of butadiene due to the couple of methyl group is also discussed. A study on the electronic properties such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The thermodynamic properties of the title compound at different temperatures reveal the correlations between standard heat capacities (C) standard entropies (S), and standard enthalpy changes (H). Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  7. Quantum Mechanical Calculations of Vibrational Sum-Frequency-Generation (SFG) Spectra of Cellulose: Dependence of the CH and OH Peak Intensity on the Polarity of Cellulose Chains within the SFG Coherence Domain.

    Science.gov (United States)

    Lee, Christopher M; Chen, Xing; Weiss, Philip A; Jensen, Lasse; Kim, Seong H

    2017-01-05

    Vibrational sum-frequency-generation (SFG) spectroscopy is capable of selectively detecting crystalline biopolymers interspersed in amorphous polymer matrices. However, the spectral interpretation is difficult due to the lack of knowledge on how spatial arrangements of crystalline segments influence SFG spectra features. Here we report time-dependent density functional theory (TD-DFT) calculations of cellulose crystallites in intimate contact with two different polarities: parallel versus antiparallel. TD-DFT calculations reveal that the CH/OH intensity ratio is very sensitive to the polarity of the crystallite packing. Theoretical calculations of hyperpolarizability tensors (β abc ) clearly show the dependence of SFG intensities on the polarity of crystallite packing within the SFG coherence length, which provides the basis for interpretation of the empirically observed SFG features of native cellulose in biological systems.

  8. Sensibility to Changes of Vibrational Modes of Excited Electron: Sum Frequency Signals Versus Difference Frequency Signals

    International Nuclear Information System (INIS)

    Gu Anna; Liang Xianting

    2011-01-01

    In this paper, we investigate a two electronic level system with vibrational modes coupled to a Brownian oscillator bath. The difference frequency generation (DFG) signals and sum frequency generation (SFG) signals are calculated. It is shown that, for the same model, the SFG signals are more sensitive than the DFG signals to the changes of the vibrational modes of the electronic two-level system. Because the SFG conversion efficiency can be improved by using the time-delay method, the findings in this paper predict that the SFG spectrum may probe the changes of the microstructure more effectively. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. Molecular Structure And Vibrational Frequencies of Tetrafluoro isophthalonitrile By Hartree-Fock And Density Functional Theory Calculations

    International Nuclear Information System (INIS)

    Ayikoglu, A.

    2008-01-01

    The molecular structure, vibrational frequencies and corresponding vibrational assignments of tetrafluoro isophthalonitrile (TFPN) in the ground state have been calculated using the Hartree-Fock (HF) and density functional methods (B3LYP) with 6-311++G (d, p) basis set. The calculations were utilized in the CS symmetry of TFPN. The obtained vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) were seen to be in good agreement with the experimental data. The comparison of the observed and calculated results showed that the B3LYP method is superior to the HF method for both the vibrational frequencies and geometric parameters

  10. Comparison of high‐intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting

    Science.gov (United States)

    Seiffert, Gary; Sutcliffe, Chris

    2015-01-01

    Abstract Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high‐intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting‐fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high‐intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117–123, 2017. PMID:26426906

  11. Relationship of the vibrational frequency of the uranyl ion with the uranium electronegativity

    International Nuclear Information System (INIS)

    Rodriguez S, A.; Martinez Q, E.

    1990-07-01

    It has been demonstrated that the vibrational asymmetric frequency of the uranyl ion, it experiences a consistent spectrochemical displacement with the variations of electronegativity of the uranium in their complexes. The values of the electronegativity of the uranium they were dear by means of calculations that it involves measures of those lengths of the connection uranium-oxygen, obtained by vibrational spectroscopy, effective nuclear charges and the Allred and Rochow equation. The results show the evidence of a natural order that relates to the vibrational frequency with the electronegativity of the uranium atom; settling down that if the electronegativity is graph against it bond length to the oxygen or to it frequency value, a simple relationship is obtained as a form to obtain clear responses in absence of complementary information. (Author)

  12. Effect of vibration frequency on microstructure and performance of high chromium cast iron prepared by lost foam casting

    Directory of Open Access Journals (Sweden)

    Wen-qi Zou

    2016-07-01

    Full Text Available In the present research, high chromium cast irons (HCCIs were prepared using the lost foam casting (LFC process. To improve the wear resistance of the high chromium cast irons (HCCIs, mechanical vibration was employed during the solidification of the HCCIs. The effects of vibration frequency on the microstructure and performance of the HCCIs under as-cast, as-quenched and as-tempered conditions were investigated. The results indicated that the microstructures of the LFC-produced HCCIs were refined due to the introduction of mechanical vibration, and the hardness was improved compared to that of the alloy without vibration. However, only a slight improvement in hardness was found in spite of the increase of vibration frequency. In contrast, the impact toughness of the as-tempered HCCIs increased with an increase in the vibration frequency. In addition, the wear resistance of the HCCIs was improved as a result of the introduction of vibration and increased with an increase in the vibration frequency.

  13. Nonlinear Vibration of Oscillation Systems using Frequency-Amplitude Formulation

    Directory of Open Access Journals (Sweden)

    A. Fereidoon

    2012-01-01

    Full Text Available In this paper we study the periodic solutions of free vibration of mechanical systems with third and fifth-order nonlinearity for two examples using He's Frequency-Amplitude Formulation (HFAF.The effectiveness and convenience of the method is illustrated in these examples. It will be shown that the solutions obtained with current method have a fabulous conformity with those achieved from time marching solution. HFAF is easy with powerful concepts and the high accuracy, so it can be found widely applicable in vibrations, especially strong nonlinearity oscillatory problems.

  14. Vibration-tolerant narrow-linewidth semiconductor disk laser using novel frequency-stabilisation schemes

    Science.gov (United States)

    Hunter, Craig R.; Jones, Brynmor E.; Schlosser, Peter; Sørensen, Simon Toft; Strain, Michael J.; McKnight, Loyd J.

    2018-02-01

    This paper will present developments in narrow-linewidth semiconductor-disk-laser systems using novel frequencystabilisation schemes for reduced sensitivity to mechanical vibrations, a critical requirement for mobile applications. Narrow-linewidth single-frequency lasers are required for a range of applications including metrology and highresolution spectroscopy. Stabilisation of the laser was achieved using a monolithic fibre-optic ring resonator with free spectral range of 181 MHz and finesse of 52 to act as passive reference cavity for the laser. Such a cavity can operate over a broad wavelength range and is immune to a wide band of vibrational frequency noise due to its monolithic implementation. The frequency noise of the locked system has been measured and compared to typical Fabry-Perotlocked lasers using vibration equipment to simulate harsh environments, and analysed here. Locked linewidths of portable, narrow-linewidth laser system for harsh environments that can be flexibly designed for a range of applications.

  15. Coupled analysis of multi-impact energy harvesting from low-frequency wind induced vibrations

    Science.gov (United States)

    Zhu, Jin; Zhang, Wei

    2015-04-01

    Energy need from off-grid locations has been critical for effective real-time monitoring and control to ensure structural safety and reliability. To harvest energy from ambient environments, the piezoelectric-based energy-harvesting system has been proven very efficient to convert high frequency vibrations into usable electrical energy. However, due to the low frequency nature of the vibrations of civil infrastructures, such as those induced from vehicle impacts, wind, and waves, the application of a traditional piezoelectric-based energy-harvesting system is greatly restrained since the output power drops dramatically with the reduction of vibration frequencies. This paper focuses on the coupled analysis of a proposed piezoelectric multi-impact wind-energy-harvesting device that can effectively up-convert low frequency wind-induced vibrations into high frequency ones. The device consists of an H-shape beam and four bimorph piezoelectric cantilever beams. The H-shape beam, which can be easily triggered to vibrate at a low wind speed, is originated from the first Tacoma Narrows Bridge, which failed at wind speeds of 18.8 m s-1 in 1940. The multi-impact mechanism between the H-shape beam and the bimorph piezoelectric cantilever beams is incorporated to improve the harvesting performance at lower frequencies. During the multi-impact process, a series of sequential impacts between the H-shape beam and the cantilever beams can trigger high frequency vibrations of the cantilever beams and result in high output power with a considerably high efficiency. In the coupled analysis, the coupled structural, aerodynamic, and electrical equations are solved to obtain the dynamic response and the power output of the proposed harvesting device. A parametric study for several parameters in the coupled analysis framework is carried out including the external resistance, wind speed, and the configuration of the H-shape beam. The average harvested power for the piezoelectric cantilever

  16. Frequency Equations for the In-Plane Vibration of Circular Annular Disks

    Directory of Open Access Journals (Sweden)

    S. Bashmal

    2010-01-01

    Full Text Available This paper deals with the in-plane vibration of circular annular disks under combinations of different boundary conditions at the inner and outer edges. The in-plane free vibration of an elastic and isotropic disk is studied on the basis of the two-dimensional linear plane stress theory of elasticity. The exact solution of the in-plane equation of equilibrium of annular disk is attainable, in terms of Bessel functions, for uniform boundary conditions. The frequency equations for different modes can be obtained from the general solutions by applying the appropriate boundary conditions at the inner and outer edges. The presented frequency equations provide the frequency parameters for the required number of modes for a wide range of radius ratios and Poisson's ratios of annular disks under clamped, free, or flexible boundary conditions. Simplified forms of frequency equations are presented for solid disks and axisymmetric modes of annular disks. Frequency parameters are computed and compared with those available in literature. The frequency equations can be used as a reference to assess the accuracy of approximate methods.

  17. Electrostatic energy harvesting device with dual resonant structure for wideband random vibration sources at low frequency.

    Science.gov (United States)

    Zhang, Yulong; Wang, Tianyang; Zhang, Ai; Peng, Zhuoteng; Luo, Dan; Chen, Rui; Wang, Fei

    2016-12-01

    In this paper, we present design and test of a broadband electrostatic energy harvester with a dual resonant structure, which consists of two cantilever-mass subsystems each with a mass attached at the free edge of a cantilever. Comparing to traditional devices with single resonant frequency, the proposed device with dual resonant structure can resonate at two frequencies. Furthermore, when one of the cantilever-masses is oscillating at resonance, the vibration amplitude is large enough to make it collide with the other mass, which provides strong mechanical coupling between the two subsystems. Therefore, this device can harvest a decent power output from vibration sources at a broad frequency range. During the measurement, continuous power output up to 6.2-9.8 μW can be achieved under external vibration amplitude of 9.3 m/s 2 at a frequency range from 36.3 Hz to 48.3 Hz, which means the bandwidth of the device is about 30% of the central frequency. The broad bandwidth of the device provides a promising application for energy harvesting from the scenarios with random vibration sources. The experimental results indicate that with the dual resonant structure, the vibration-to-electricity energy conversion efficiency can be improved by 97% when an external random vibration with a low frequency filter is applied.

  18. Calculation of vibrational frequencies through a variational reduced-coupling approach.

    Science.gov (United States)

    Scribano, Yohann; Benoit, David M

    2007-10-28

    In this study, we present a new method to perform accurate and efficient vibrational configuration interaction computations for large molecular systems. We use the vibrational self-consistent field (VSCF) method to compute an initial description of the vibrational wave function of the system, combined with the single-to-all approach to compute a sparse potential energy surface at the chosen ab initio level of theory. A Davidson scheme is then used to diagonalize the Hamiltonian matrix built on the VSCF virtual basis. Our method is applied to the computation of the OH-stretch frequency of formic acid and benzoic acid to demonstrate the efficiency and accuracy of this new technique.

  19. Simultaneous rotational and vibrational CARS generation through a multiple-frequency combination technique

    International Nuclear Information System (INIS)

    Alden, M.; Bengtsson, P.E.; Edner, H.

    1987-01-01

    One most promising laser technique for probing combustion processes is coherent anti-Stokes Raman scattering (CARS), which due to its coherent nature and signal strength is applied in several real-world applications. Until today almost all CARS experiments are based on probing the population of molecular vibrational energy levels. However, there are several reasons rotational CARS, i.e. probing of rotational energy levels, may provide a complement to or even a better choice than vibrational CARS. Recently an alternative way to produce rotational CARS spectra is proposed, which is based on a multiple-frequency combination technique. The energy-level diagram for this process is presented. Two dye laser beams at ω/sub r/, and one fix frequency laser beam at ω/sub g/ are employed. ω/sub r,1/ and ω/sub r,2/ are two frequencies of many possible pairs with a frequency difference matching a rotational transition in a molecule. The excitation induced by ω/sub r,1/ and ω/sub r,2/ is then scattered by the narrowband ω/sub g/ beam resulting in a CARS beam ω/sub g/ at ω/sub g/ + ω/sub r,1/ - ω/sub r,2/. An interesting feature with this technique is that it is possible to generate simultaneously a rotational and vibrational CARS spectrum by using a double-folded boxcars phase matching approach. The authors believe that the proposed technique for producing rotational and vibration CARS spectra could be of interest, e.g., when measuring in highly turbulent flows. In this case the rotational CARS spectra could use for temperature measurements in the cooler parts, whereas vibrational CARS are to be preferred when measuring in the hotter parts

  20. Molecular-level mechanisms of vibrational frequency shifts in a polar liquid.

    Science.gov (United States)

    Morales, Christine M; Thompson, Ward H

    2011-06-16

    A molecular-level analysis of the origins of the vibrational frequency shifts of the CN stretching mode in neat liquid acetonitrile is presented. The frequency shifts and infrared spectrum are calculated using a perturbation theory approach within a molecular dynamics simulation and are in good agreement with measured values reported in the literature. The resulting instantaneous frequency of each nitrile group is decomposed into the contributions from each molecule in the liquid and by interaction type. This provides a detailed picture of the mechanisms of frequency shifts, including the number of surrounding molecules that contribute to the shift, the relationship between their position and relative contribution, and the roles of electrostatic and van der Waals interactions. These results provide insight into what information is contained in infrared (IR) and Raman spectra about the environment of the probed vibrational mode. © 2011 American Chemical Society

  1. Frequencies in the Vibration Induced by the Rotor Stator Interaction in a Centrifugal Pump Turbine

    DEFF Research Database (Denmark)

    Rodriguez, Cristian; Egusquiza, Eduard; Santos, Ilmar

    2007-01-01

    The highest vibration levels in large pump turbines are, in general, originated in the rotor stator interaction (RSI). This vibration has specific characteristics that can be clearly observed in the frequency domain: harmonics of the moving blade passing frequency and a particular relationship am...

  2. Research of hydroelectric generating set low-frequency vibration monitoring system based on optical fiber sensing

    Science.gov (United States)

    Min, Li; Zhang, Xiaolei; Zhang, Faxiang; Sun, Zhihui; Li, ShuJuan; Wang, Meng; Wang, Chang

    2017-10-01

    In order to satisfy hydroelectric generating set low-frequency vibration monitoring, the design of Passive low-frequency vibration monitoring system based on Optical fiber sensing in this paper. The hardware of the system adopts the passive optical fiber grating sensor and unbalanced-Michelson interferometer. The software system is used to programming by Labview software and finishing the control of system. The experiment show that this system has good performance on the standard vibration testing-platform and it meets system requirements. The frequency of the monitoring system can be as low as 0.2Hz and the resolution is 0.01Hz.

  3. Vibrational frequencies and structural investigation of (M(CN)4)2- (M Cd, Hg and Zn) ions

    International Nuclear Information System (INIS)

    Gurkan, Keshan; Tomas, Polivka; Cemal, Parlak; Mustafa, Shenyel

    2011-01-01

    The normal mode frequencies and corresponding vibrational assignments of tetracyanometallate (II) ions ([M(CN) 4 ] 2 -, M = Cd, Hg and Zn) have been theoretically examined by means of standard quantum chemical techniques. All normalmodes have been successfully assigned to one of six types of motion utilizing the T d symmetry of M(CN) 4 2 -. Calculations have been performed at the Becke-3-Lee-Yang-Parr (B3LYP) density functional method using the Lanl2dz effective core basis set. Furthermore, reliable vibrational assignments have been made on the basis of potential energy distribution (PED) calculated and the thermodynamics functions, highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO) of the title ions have been predicted together with their infrared intensities and Raman activities. Theoretical results have been successfully compared against available experimental data

  4. Nonlinear resonance ultrasonic vibrations in Czochralski-silicon wafers

    Science.gov (United States)

    Ostapenko, S.; Tarasov, I.

    2000-04-01

    A resonance effect of generation of subharmonic acoustic vibrations is observed in as-grown, oxidized, and epitaxial silicon wafers. Ultrasonic vibrations were generated into a standard 200 mm Czochralski-silicon (Cz-Si) wafer using a circular ultrasound transducer with major frequency of the radial vibrations at about 26 kHz. By tuning frequency (f) of the transducer within a resonance curve, we observed a generation of intense f/2 subharmonic acoustic mode assigned as a "whistle." The whistle mode has a threshold amplitude behavior and narrow frequency band. The whistle is attributed to a nonlinear acoustic vibration of a silicon plate. It is demonstrated that characteristics of the whistle mode are sensitive to internal stress and can be used for quality control and in-line diagnostics of oxidized and epitaxial Cz-Si wafers.

  5. Separate recording of rationally related vibration frequencies using digital stroboscopic holographic interferometry

    International Nuclear Information System (INIS)

    Alexeenko, Igor; Gusev, Michael; Gurevich, Vadim

    2009-01-01

    A method for separate recording of rationally related vibration frequencies is presented. To record and measure the mode shape of vibrations, a synchronized stroboscopic CCD camera is used. Synchronization and control of the camera acquisition for recording stroboscopic holographic sequence has been realized. The phase for different states of the object vibration is calculated using the Fourier-transform method. Experimental results are presented, and the advantages and disadvantages of the proposed method are discussed.

  6. Prediction of absolute infrared intensities for the fundamental vibrations of H2O2

    Science.gov (United States)

    Rogers, J. D.; Hillman, J. J.

    1981-01-01

    Absolute infrared intensities are predicted for the vibrational bands of gas-phase H2O2 by the use of a hydrogen atomic polar tensor transferred from the hydroxyl hydrogen atom of CH3OH. These predicted intensities are compared with intensities predicted by the use of a hydrogen atomic polar tensor transferred from H2O. The predicted relative intensities agree well with published spectra of gas-phase H2O2, and the predicted absolute intensities are expected to be accurate to within at least a factor of two. Among the vibrational degrees of freedom, the antisymmetric O-H bending mode nu(6) is found to be the strongest with a calculated intensity of 60.5 km/mole. The torsional band, a consequence of hindered rotation, is found to be the most intense fundamental with a predicted intensity of 120 km/mole. These results are compared with the recent absolute intensity determinations for the nu(6) band.

  7. Sensitivity analysis of the stiffness between the frame structure and the frequency and vibration mode

    Science.gov (United States)

    Chen, Wenyuan

    2018-03-01

    The modal parameters such as natural frequency and vibration mode of the frame structure of the layer stiffness sensitivity is inconsistent. This article focuses on the theoretical derivation of the frequency and mode of the frame structure layer stiffness of the first-order sensitivity. The numerical examples show that the frame structure of layer stiffness higher than with the first order sensitivity vibration frequency.

  8. Vibration-induced particle formation during yogurt fermentation-Effect of frequency and amplitude.

    Science.gov (United States)

    Körzendörfer, Adrian; Temme, Philipp; Schlücker, Eberhard; Hinrichs, Jörg; Nöbel, Stefan

    2018-05-01

    Machinery such as pumps used for the commercial production of fermented milk products cause vibrations that can spread to the fermentation tanks. During fermentation, such vibrations can disturb the gelation of milk proteins by causing texture defects including lumpiness and syneresis. To study the effect of vibrations on yogurt structure systematically, an experimental setup was developed consisting of a vibration exciter to generate defined vibrational states and accelerometers for monitoring. During the fermentation of skim milk, vibrations (frequency sweep: 25 to 1,005 Hz) were introduced at different pH (5.7 to 5.1, step width 0.1 units) for 200 s. Physical properties of set gels (syneresis, firmness) and resultant stirred yogurts (visible particles, rheology, laser diffraction) were analyzed. Vibrational treatments at pH 5.5 to 5.2 increased syneresis, gel firmness, and the number of large particles (d > 0.9 mm); hence, this period was considered critical. The particle number increased from 34 ± 5 to 242 ± 16 particles per 100 g of yogurt due to vibrations at pH 5.4. In further experiments, yogurts were excited with fixed frequencies (30, 300, and 1,000 Hz). All treatments increased syneresis, firmness, and particle formation. As the strongest effect was observed by applying 30 Hz, the amplitude was set to vibration accelerations of a = 5, 10, 15, 20, and 25 m/s 2 in the final experiments. The number of large particles was increased due to each treatment and a positive correlation with the amplitude was found. We concluded that vibrations during gelation increase the collision probability of aggregating milk proteins, resulting in a compressed set gel with syneresis. Resultant stirred yogurts exhibit large particles with a compact structure leading to a reduced water-holding capacity and product viscosity. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  9. Relationship Between Psychomotor Efficiency and Sensation Seeking of People Exposed to Noise and Low Frequency Vibration Stimuli

    Science.gov (United States)

    Korchut, Aleksander; Kowalska-Koczwara, Alicja; Romanska – Zapała, Anna; Stypula, Krzysztof

    2017-10-01

    At the workplace of the machine operator, low frequency whole body and hand- arm vibrations are observed. They occur together with noise. Whole body vibration in the range of 3-25 Hz are detrimental to the human body due to the location of the resonant frequency of large organs of the human body in this range. It can be assumed that for this reason people working every day in such conditions can have reduced working efficiency. The influence of low frequency vibration and noise on the human body leads to both physiological and functional changes. The result of the impact of noise and vibration stimuli depends largely on the specific characteristics of the objects, which include among other personality traits, temperament and emotional factor. The pilot study conducted in the laboratory was attended by 30 young men. The aim of the study was to look for correlations between the need for stimulation of the objects and their psychomotor efficiency in case of vibration exposure and vibration together with noise exposure in variable conditions task. The need for stimulation of the objects as defined in the study is based on theoretical assumptions of one dimensional model of temperament developed by Marvin Zuckerman. This theory defines the need for stimulation as the search for different, new, complex and intense sensations, as well as the willingness to take risks. The aim of research was to verify if from four factors such as: the search for adventure and horror, sensation seeking, disinhibition and susceptibility to boredom, we can choose the ones that in conjunction with varying operating conditions, may significantly determine the efficiency of the task situation. The objects performed the test evaluation of their motor skills which consisted in keeping the cursor controlled by a joystick through the path. The number of exceeds of the cursor beyond the path and its maximum deviation was recorded. The collected data were used to determine the correlation between the

  10. An extension of command shaping methods for controlling residual vibration using frequency sampling

    Science.gov (United States)

    Singer, Neil C.; Seering, Warren P.

    1992-01-01

    The authors present an extension to the impulse shaping technique for commanding machines to move with reduced residual vibration. The extension, called frequency sampling, is a method for generating constraints that are used to obtain shaping sequences which minimize residual vibration in systems such as robots whose resonant frequencies change during motion. The authors present a review of impulse shaping methods, a development of the proposed extension, and a comparison of results of tests conducted on a simple model of the space shuttle robot arm. Frequency shaping provides a method for minimizing the impulse sequence duration required to give the desired insensitivity.

  11. Comparison of high-intensity sound and mechanical vibration for cleaning porous titanium cylinders fabricated using selective laser melting.

    Science.gov (United States)

    Seiffert, Gary; Hopkins, Carl; Sutcliffe, Chris

    2017-01-01

    Orthopedic components, such as the acetabular cup in total hip joint replacement, can be fabricated using porous metals, such as titanium, and a number of processes, such as selective laser melting. The issue of how to effectively remove loose powder from the pores (residual powder) of such components has not been addressed in the literature. In this work, we investigated the feasibility of two processes, acoustic cleaning using high-intensity sound inside acoustic horns and mechanical vibration, to remove residual titanium powder from selective laser melting-fabricated cylinders. With acoustic cleaning, the amount of residual powder removed was not influenced by either the fundamental frequency of the horn used (75 vs. 230 Hz) or, for a given horn, the number of soundings (between 1 and 20). With mechanical vibration, the amount of residual powder removed was not influenced by the application time (10 vs. 20 s). Acoustic cleaning was found to be more reliable and effective in removal of residual powder than cleaning with mechanical vibration. It is concluded that acoustic cleaning using high-intensity sound has significant potential for use in the final preparation stages of porous metal orthopedic components. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 117-123, 2017. © 2015 The Authors Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

  12. Low frequency phase signal measurement with high frequency squeezing

    OpenAIRE

    Zhai, Zehui; Gao, Jiangrui

    2011-01-01

    We calculate the utility of high-frequency squeezed-state enhanced two-frequency interferometry for low-frequency phase measurement. To use the high-frequency sidebands of the squeezed light, a two-frequency intense laser is used in the interferometry instead of a single-frequency laser as usual. We find that the readout signal can be contaminated by the high-frequency phase vibration, but this is easy to check and avoid. A proof-of-principle experiment is in the reach of modern quantum optic...

  13. The effect of classical and quantum dynamics on vibrational frequency shifts of H2 in clathrate hydrates

    International Nuclear Information System (INIS)

    Plattner, Nuria; Meuwly, Markus

    2014-01-01

    Vibrational frequency shifts of H 2 in clathrate hydrates are important to understand the properties and elucidate details of the clathrate structure. Experimental spectra of H 2 in clathrate hydrates have been measured for different clathrate compositions, temperatures, and pressures. In order to establish reliable relationships between the clathrate structure, dynamics, and observed frequencies, calculations of vibrational frequency shifts in different clathrate environments are required. In this study, a combination of classical molecular dynamics simulations, electronic structure calculations, and quantum dynamical simulation is used to calculate relative vibrational frequencies of H 2 in clathrate hydrates. This approach allows us to assess dynamical effects and simulate the change of vibrational frequencies with temperature and pressure. The frequency distributions of the H 2 vibrations in the different clathrate cage types agree favorably with experiment. Also, the simulations demonstrate that H 2 in the 5 12 cage is more sensitive to the details of the environment and to quantum dynamical effects, in particular when the cage is doubly occupied. We show that for the 5 12 cage quantum effects lead to frequency increases and double occupation is unlikely. This is different for the 5 12 6 4 cages for which higher occupation numbers than one H 2 per cage are likely

  14. Rotational structure of the five lowest frequency fundamental vibrational states of dimethylsulfoxide

    Science.gov (United States)

    Cuisset, Arnaud; Drumel, Marie-Aline Martin; Hindle, Francis; Mouret, Gaël; Sadovskií, Dmitrií A.

    2013-10-01

    We report on the successful extended analysis of the high-frequency (200-700 GHz) part of the gas phase (sub)mm-wave spectra of dimethylsulfoxide (DMSO). The spectrum was recorded at 100 kHz resolution using a solid state subTHz spectrometer. The five lowest energy fundamental vibrational states of DMSO with frequencies below 400 cm-1 were observed as sidebands along with the main 0←0 band. Neglecting the internal rotation of methyls, our rotational Hamiltonian reproduced the spectrum to the subMHz accuracy. We have found that the asymmetric bending state ν23 is the only low frequency fundamental vibrational state with the "anomalous" rotational structure uncovered in Cuisset et al. [1]. dmsomw 2013-09-04 15:03

  15. Dual resonant structure for energy harvesting from random vibration sources at low frequency

    Directory of Open Access Journals (Sweden)

    Shanshan Li

    2016-01-01

    Full Text Available We introduce a design with dual resonant structure which can harvest energy from random vibration sources at low frequency range. The dual resonant structure consists of two spring-mass subsystems with different frequency responses, which exhibit strong coupling and broad bandwidth when the two masses collide with each other. Experiments with piezoelectric elements show that the energy harvesting device with dual resonant structure can generate higher power output than the sum of the two separate devices from random vibration sources.

  16. First-Principles Studies of Pentaerythritol Tetranitrate (PETN) Single Crystal Unit Cell Volumes and Vibrational Frequencies under Hydrostatic Pressure

    Science.gov (United States)

    Perger, Warren F.; Zhao, Jijun; Winey, J. M.; Gupta, Y. M.

    2006-07-01

    The vibrational frequencies of the PETN molecular crystal were calculated using the first-principles CRYSTAL03 program which employs an all-electron LCAO approach and calculates analytic first derivatives of the total energy with respect to atomic displacements. Numerical second derivatives were used to enable calculation of the vibrational frequencies at ambient pressure and under various states of compression. Three different density functionals, B3LYP, PW91, and X3LYP were used to examine the effect of the exchange-correlation functional on the vibrational frequencies. The average deviation with experimental results is shown to be on the order of 2-3%, depending on the functional used. The pressure-induced shift of the vibrational frequencies is presented.

  17. Non-linear Vibration of Oscillation Systems using Frequency-Amplitude Formulation

    DEFF Research Database (Denmark)

    Fereidoon, A.; Ghadimi, M.; Barari, Amin

    2012-01-01

    In this paper we study the periodic solutions of free vibration of mechanical systems with third and fifthorder nonlinearity for two examples using He’s Frequency Amplitude Formulation (HFAF).The effectiveness and convenience of the method is illustrated in these examples. It will be shown that t...... that the solutions obtained with current method have a fabulous conformity with those achieved from time marching solution. HFAF is easy with powerful concepts and the high accuracy, so it can be found widely applicable in vibrations, especially strong nonlinearity oscillatory problems....

  18. Frequency-varying synchronous micro-vibration suppression for a MSFW with application of small-gain theorem

    Science.gov (United States)

    Peng, Cong; Fan, Yahong; Huang, Ziyuan; Han, Bangcheng; Fang, Jiancheng

    2017-01-01

    This paper presents a novel synchronous micro-vibration suppression method on the basis of the small gain theorem to reduce the frequency-varying synchronous micro-vibration forces for a magnetically suspended flywheel (MSFW). The proposed synchronous micro-vibration suppression method not only eliminates the synchronous current fluctuations to force the rotor spinning around the inertia axis, but also considers the compensation caused by the displacement stiffness in the permanent-magnet (PM)-biased magnetic bearings. Moreover, the stability of the proposed control system is exactly analyzed by using small gain theorem. The effectiveness of the proposed micro-vibration suppression method is demonstrated via the direct measurement of the disturbance forces for a MSFW. The main merit of the proposed method is that it provides a simple and practical method in suppressing the frequency varying micro-vibration forces and preserving the nominal performance of the baseline control system.

  19. High Frequency Longitudinal Damped Vibrations of a Cylindrical Ultrasonic Transducer

    Directory of Open Access Journals (Sweden)

    Mihai Valentin Predoi

    2014-01-01

    Full Text Available Ultrasonic piezoelectric transducers used in classical nondestructive testing are producing in general longitudinal vibrations in the MHz range. A simple mechanical model of these transducers would be very useful for wave propagation numerical simulations, avoiding the existing complicated models in which the real components of the transducer are modeled by finite elements. The classical model for longitudinal vibrations is not adequate because the generated longitudinal wave is not dispersive, the velocity being the same at any frequency. We have adopted the Rayleigh-Bishop model, which avoids these limitations, even if it is not converging to the first but to the second exact longitudinal mode in an elastic rod, as obtained from the complicated Pochhammer-Chree equations. Since real transducers have significant vibrations damping, we have introduced a damping term in the Rayleigh-Bishop model, increasing the imaginary part and keeping almost identical real part of the wavenumber. Common transducers produce amplitude modulated signals, completely attenuated after several periods. This can be modeled by two close frequencies, producing a “beat” phenomenon, superposed on the high damping. For this reason, we introduce a two-rod Rayleigh-Bishop model with damping. Agreement with measured normal velocity on the transducer free surface is encouraging for continuation of the research.

  20. Determination of low-frequency vibrational states in glasses

    International Nuclear Information System (INIS)

    Ahmad, N.; Hasan, M.M.

    1996-01-01

    It is shown that density of low frequency (v < 1 THz) vibrational states g(v) in glasses can be determined from heat capacities measured at low temperature. These g(v) are identical to those determined from inelastic neutron scattering studies. The form of g(v) is non quadratic and therefore the Debye density of states may not be used to interpret the Raman, and infrared absorption in glasses. (author)

  1. Distributed Fiber-Optic Sensors for Vibration Detection.

    Science.gov (United States)

    Liu, Xin; Jin, Baoquan; Bai, Qing; Wang, Yu; Wang, Dong; Wang, Yuncai

    2016-07-26

    Distributed fiber-optic vibration sensors receive extensive investigation and play a significant role in the sensor panorama. Optical parameters such as light intensity, phase, polarization state, or light frequency will change when external vibration is applied on the sensing fiber. In this paper, various technologies of distributed fiber-optic vibration sensing are reviewed, from interferometric sensing technology, such as Sagnac, Mach-Zehnder, and Michelson, to backscattering-based sensing technology, such as phase-sensitive optical time domain reflectometer, polarization-optical time domain reflectometer, optical frequency domain reflectometer, as well as some combinations of interferometric and backscattering-based techniques. Their operation principles are presented and recent research efforts are also included. Finally, the applications of distributed fiber-optic vibration sensors are summarized, which mainly include structural health monitoring and perimeter security, etc. Overall, distributed fiber-optic vibration sensors possess the advantages of large-scale monitoring, good concealment, excellent flexibility, and immunity to electromagnetic interference, and thus show considerable potential for a variety of practical applications.

  2. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    OpenAIRE

    Chee, Hyun Keun; Oh, S. June

    2013-01-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine ...

  3. Calculation of mechanical vibration frequencies of stiffened superconducting cavities

    International Nuclear Information System (INIS)

    Black, S.J.; Spalek, G.

    1992-01-01

    We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL- modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations

  4. Protonated Nitrous Oxide, NNOH(+): Fundamental Vibrational Frequencies and Spectroscopic Constants from Quartic Force Fields

    Science.gov (United States)

    Huang, Xinchuan; Fortenberry, Ryan C.; Lee, Timothy J.

    2013-01-01

    The interstellar presence of protonated nitrous oxide has been suspected for some time. Using established high-accuracy quantum chemical techniques, spectroscopic constants and fundamental vibrational frequencies are provided for the lower energy O-protonated isomer of this cation and its deuterated isotopologue. The vibrationally-averaged B0 and C0 rotational constants are within 6 MHz of their experimental values and the D(subJ) quartic distortion constants agree with experiment to within 3%. The known gas phase O-H stretch of NNOH(+) is 3330.91 cm(exp-1), and the vibrational configuration interaction computed result is 3330.9 cm(exp-1). Other spectroscopic constants are also provided, as are the rest of the fundamental vibrational frequencies for NNOH(+) and its deuterated isotopologue. This high-accuracy data should serve to better inform future observational or experimental studies of the rovibrational bands of protonated nitrous oxide in the ISM and the laboratory.

  5. A novel vision-based mold monitoring system in an environment of intense vibration

    International Nuclear Information System (INIS)

    Hu, Fen; He, Zaixing; Zhao, Xinyue; Zhang, Shuyou

    2017-01-01

    Mold monitoring has been more and more widely used in the modern manufacturing industry, especially when based on machine vision, but these systems cannot meet the detection speed and accuracy requirements for mold monitoring because they must operate in environments that exhibit intense vibration during production. To ensure that the system runs accurately and efficiently, we propose a new descriptor that combines the geometric relationship-based global context feature and the local scale-invariant feature transform for the image registration step of the mold monitoring system. The experimental results of four types of molds showed that the detection accuracy of the mold monitoring system is improved in the environment with intense vibration. (paper)

  6. A novel vision-based mold monitoring system in an environment of intense vibration

    Science.gov (United States)

    Hu, Fen; He, Zaixing; Zhao, Xinyue; Zhang, Shuyou

    2017-10-01

    Mold monitoring has been more and more widely used in the modern manufacturing industry, especially when based on machine vision, but these systems cannot meet the detection speed and accuracy requirements for mold monitoring because they must operate in environments that exhibit intense vibration during production. To ensure that the system runs accurately and efficiently, we propose a new descriptor that combines the geometric relationship-based global context feature and the local scale-invariant feature transform for the image registration step of the mold monitoring system. The experimental results of four types of molds showed that the detection accuracy of the mold monitoring system is improved in the environment with intense vibration.

  7. Pattern recognition based on time-frequency analysis and convolutional neural networks for vibrational events in φ-OTDR

    Science.gov (United States)

    Xu, Chengjin; Guan, Junjun; Bao, Ming; Lu, Jiangang; Ye, Wei

    2018-01-01

    Based on vibration signals detected by a phase-sensitive optical time-domain reflectometer distributed optical fiber sensing system, this paper presents an implement of time-frequency analysis and convolutional neural network (CNN), used to classify different types of vibrational events. First, spectral subtraction and the short-time Fourier transform are used to enhance time-frequency features of vibration signals and transform different types of vibration signals into spectrograms, which are input to the CNN for automatic feature extraction and classification. Finally, by replacing the soft-max layer in the CNN with a multiclass support vector machine, the performance of the classifier is enhanced. Experiments show that after using this method to process 4000 vibration signal samples generated by four different vibration events, namely, digging, walking, vehicles passing, and damaging, the recognition rates of vibration events are over 90%. The experimental results prove that this method can automatically make an effective feature selection and greatly improve the classification accuracy of vibrational events in distributed optical fiber sensing systems.

  8. Crack recognition on vertical rotors by means of frequency selective vibration monitoring

    International Nuclear Information System (INIS)

    Nink, A.; Stoelben, H.

    1990-01-01

    Shaft cracks on primary coolant pumps in pressurized water reactors have led to intensive vibration monitoring, in particular of vertically arranged rotors. However, the interpretation of shaft vibrations with respect to crack recognition proved to be very difficult. Appropriate experimental approaches resulted in an improved interpretation base. The article describes both the problems related to primary coolant pumps and first experimental experience gained from tests on a pre-cracked vertical rotor. Differential vectors of rotational speed harmonics provide an optimum description of the effect of a crack on shaft vibration. Diagnostics can be supported by observing the vectors, while purposefully changing axial loads. (orig.) [de

  9. Nonlinear laser dynamics induced by frequency shifted optical feedback: application to vibration measurements.

    Science.gov (United States)

    Girardeau, Vadim; Goloni, Carolina; Jacquin, Olivier; Hugon, Olivier; Inglebert, Mehdi; Lacot, Eric

    2016-12-01

    In this article, we study the nonlinear dynamics of a laser subjected to frequency shifted optical reinjection coming back from a vibrating target. More specifically, we study the nonlinear dynamical coupling between the carrier and the vibration signal. The present work shows how the nonlinear amplification of the vibration spectrum is related to the strength of the carrier and how it must be compensated to obtain accurate (i.e., without bias) vibration measurements. The theoretical predictions, confirmed by numerical simulations, are in good agreement with the experimental data. The main motivation of this study is the understanding of the nonlinear response of a laser optical feedback imaging sensor for quantitative phase measurements of small vibrations in the case of strong optical feedback.

  10. Synchrotron radiation in the Far-Infrared: Adsorbate-substrate vibrations and resonant interactions

    International Nuclear Information System (INIS)

    Hoffmann, F.M.; Williams, G.P.; Hirschmugl, C.J.; Chabal, Y.J.

    1991-01-01

    Synchrotron radiation in the Far Infrared offers the potential for a broadband source of high brightness and intensity. Recent development of a Far-Infrared Beamline at the NSLS in Brookhaven provides an unique high intensity source in the FIR spectral range (800-10 cm -1 ). This talk reviews its application to surface vibrational spectroscopy of low frequency adsorbate-substrate vibrations and resonant interactions on metal surfaces

  11. Low-cost vibration sensor based on dual fiber Bragg gratings and light intensity measurement.

    Science.gov (United States)

    Gao, Xueqing; Wang, Yongjiao; Yuan, Bo; Yuan, Yinquan; Dai, Yawen; Xu, Gang

    2013-09-20

    A vibration monitoring system based on light intensity measurement has been constructed, and the designed accelerometer is based on steel cantilever frame and dual fiber Bragg gratings (FBGs). By using numerical simulations for the dual FBGs, the dependence relationship of the area of main lobes on the difference of initial central wavelengths is obtained and the most optimal choice for the initial value and the vibration amplitude of the difference of central wavelengths of two FBGs is suggested. The vibration monitoring experiments are finished, and the measured data are identical to the simulated results.

  12. Acute effects of a vibration-like stimulus during knee extension exercise.

    Science.gov (United States)

    Mileva, Katya N; Naleem, Asif A; Biswas, Santonu K; Marwood, Simon; Bowtell, Joanna L

    2006-07-01

    This study was conducted to test whether a low-frequency vibration-like stimulus (rapid variable resistance) applied during a single session of knee extension exercise would alter muscle performance. Torque, knee joint angle, EMG activity of rectus femoris (RF) and vastus lateralis (VL) muscles, and VL muscle oxygenation status (near-infrared spectroscopy) were recorded during metronome-guided knee extension exercise. Nine healthy adults completed four trials exercising at contraction intensities of 35% (L) or 70% (H) of one-repetition maximum (1RM) in control (no vibration, Vb-) or vibrated condition (superimposed 10-Hz vibration-like stimulus, Vb+). Maximum voluntary contraction and 1RM were tested pre- and postexercise. During 1RM tests, muscle dynamic strength (P=0.02) and power (P=0.05) were significantly higher during vibrated rather than nonvibrated trials, and strength was significantly higher post- than preexercise (P=0.002), except during LVb- trial. Median spectral frequency of VL and RF EMG activity was significantly higher during postexercise than preexercise 1RM test in the vibration trials but unchanged in the control trials (Pvibration superimposition tended to speed muscle deoxygenation rate (P=0.065, 36% effect size) particularly during L trials. Vibration superimposition during knee extension exercise at low contraction intensity enhanced muscle performance. This effect appears to result from adaptation of neural factors such as motor unit excitability (recruitment and firing frequency, conduction velocity of excitation) in response to sensory receptor stimulation. Muscle vibration may increase the training effects derived from light-to-moderate exercise.

  13. Calculation of mechanical vibration frequencies of stiffened superconducting cavities

    International Nuclear Information System (INIS)

    Black, S.J.; Spalek, G.

    1992-01-01

    We calculated the frequencies of transverse and longitudinal mechanical-vibration modes of the HEPL-modified, CERN/DESY four-cell superconducting cavity, using finite-element techniques. We compared the results of these calculations, including the stiffening of the cavity with rods, with mode frequencies measured at HEPL. The correlation between data was significant. The same techniques were also used to design and optimize the stiffening scheme for the seven-cell 805-MHz superconducting cavity being developed at Los Alamos. In this report, we describe the final stiffening scheme and the results of our calculations. (Author) 6 figs., 5 tabs., 4 refs

  14. Molecular Structure And Vibrational Frequencies of 2,3,4 Nitro anilines By Hartree-Fock And Density Functional Theory Calculations

    International Nuclear Information System (INIS)

    Sert, Y.

    2008-01-01

    The optimised molecular structure, vibrational frequencies and corresponding vibrational assignments of 2-, 3- and 4- nitro anilines have been calculated using the Hartree-Fock (HF) and density functional methods (B3LYP) with 6-311++G (d, p) basis set. The calculations were adapted to the C S symmetries of all the molecules. The calculated vibrational frequencies and geometric parameters (bond lengths and bond angles) were seen to be in good agreement with the experimental data. The comparison of the experimental and theoretical results showed that the HF method is superior to the B3LYP method for both the vibrational frequencies and geometric parameters

  15. Note: A component-level frequency tunable isolator for vibration-sensitive chips using SMA beams

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaoyong, E-mail: zhangxy@buaa.edu.cn, E-mail: yanxiaojun@buaa.edu.cn; Yan, Xiaojun, E-mail: zhangxy@buaa.edu.cn, E-mail: yanxiaojun@buaa.edu.cn [School of Energy and Power Engineering, Beihang University, Beijing 100191 (China); Collaborative Innovation Center of Advanced Aero-Engine, Beijing 100191 (China); National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics, Beijing 100191 (China); Beijing Key Laboratory of Aero-Engine Structure and Strength, Beijing 100191 (China); Ding, Xin; Wu, Di; Qi, Junlei; Wang, Ruixin; Lu, Siwei [School of Energy and Power Engineering, Beihang University, Beijing 100191 (China)

    2016-06-15

    This note presents a component-level frequency tunable isolator for vibration-sensitive chips. The isolator employed 8 U-shaped shape memory alloy (SMA) beams to support an isolation island (used for mounting chips). Due to the temperature-induced Young’s modulus variation of SMA, the system stiffness of the isolator can be controlled through heating the SMA beams. In such a way, the natural frequency of the isolator can be tuned. A prototype was fabricated to evaluate the concept. The test results show that the natural frequency of the isolator can be tuned in the range of 64 Hz–97 Hz by applying different heating strategies. Moreover, resonant vibration can be suppressed significantly (the transmissibility decreases about 65% near the resonant frequency) using a real-time tuning method.

  16. Note: A component-level frequency tunable isolator for vibration-sensitive chips using SMA beams

    International Nuclear Information System (INIS)

    Zhang, Xiaoyong; Yan, Xiaojun; Ding, Xin; Wu, Di; Qi, Junlei; Wang, Ruixin; Lu, Siwei

    2016-01-01

    This note presents a component-level frequency tunable isolator for vibration-sensitive chips. The isolator employed 8 U-shaped shape memory alloy (SMA) beams to support an isolation island (used for mounting chips). Due to the temperature-induced Young’s modulus variation of SMA, the system stiffness of the isolator can be controlled through heating the SMA beams. In such a way, the natural frequency of the isolator can be tuned. A prototype was fabricated to evaluate the concept. The test results show that the natural frequency of the isolator can be tuned in the range of 64 Hz–97 Hz by applying different heating strategies. Moreover, resonant vibration can be suppressed significantly (the transmissibility decreases about 65% near the resonant frequency) using a real-time tuning method.

  17. The vibrating reed frequency meter: digital investigation of an early cochlear model

    Directory of Open Access Journals (Sweden)

    Andrew Bell

    2015-10-01

    Full Text Available The vibrating reed frequency meter, originally employed by Békésy and later by Wilson as a cochlear model, uses a set of tuned reeds to represent the cochlea’s graded bank of resonant elements and an elastic band threaded between them to provide nearest-neighbour coupling. Here the system, constructed of 21 reeds progressively tuned from 45 to 55 Hz, is simulated numerically as an elastically coupled bank of passive harmonic oscillators driven simultaneously by an external sinusoidal force. To uncover more detail, simulations were extended to 201 oscillators covering the range 1–2 kHz. Calculations mirror the results reported by Wilson and show expected characteristics such as traveling waves, phase plateaus, and a response with a broad peak at a forcing frequency just above the natural frequency. The system also displays additional fine-grain features that resemble those which have only recently been recognised in the cochlea. Thus, detailed analysis brings to light a secondary peak beyond the main peak, a set of closely spaced low-amplitude ripples, rapid rotation of phase as the driving frequency is swept, frequency plateaus, clustering, and waxing and waning of impulse responses. Further investigation shows that each reed’s vibrations are strongly localised, with small energy flow along the chain. The distinctive set of equally spaced ripples is an inherent feature which is found to be largely independent of boundary conditions. Although the vibrating reed model is functionally different to the standard transmission line, its cochlea-like properties make it an intriguing local oscillator model whose relevance to cochlear mechanics needs further investigation.

  18. Vibrational characteristics of FRP-bonded concrete interfacial defects in a low frequency regime

    Science.gov (United States)

    Cheng, Tin Kei; Lau, Denvid

    2014-04-01

    As externally bonded fiber-reinforced polymer (FRP) is a critical load-bearing component of strengthened or retrofitted civil infrastructures, the betterment of structural health monitoring (SHM) methodology for such composites is imperative. Henceforth the vibrational characteristics of near surface interfacial defects involving delamination and trapped air pockets at the FRP-concrete interface are investigated in this study using a finite element approach. Intuitively, due to its lower interfacial stiffness compared with an intact interface, a damaged region is expected to have a set of resonance frequencies different from an intact region when excited by acoustic waves. It has been observed that, when excited acoustically, both the vibrational amplitudes and frequency peaks in the response spectrum of the defects demonstrate a significant deviation from an intact FRP-bonded region. For a thin sheet of FRP bonded to concrete with sizable interfacial defects, the fundamental mode under free vibration is shown to be relatively low, in the order of kHz. Due to the low resonance frequencies of the defects, the use of low-cost equipment for interfacial defect detection via response spectrum analysis is highly feasible.

  19. Vibrational frequencies and dephasing times in excited electronic states by femtosecond time-resolved four-wave mixing

    Science.gov (United States)

    Joo, Taiha; Albrecht, A. C.

    1993-06-01

    Time-resolved degenerate four-wave mixing (TRDFWM) for an electronically resonant system in a phase-matching configuration that measures population decay is reported. Because the spectral width of input light exceeds the vibrational Bohr frequency of a strong Raman active mode, the vibrational coherence produces strong oscillations in the TRDFWM signal together with the usual population decay from the excited electronic state. The data are analyzed in terms of a four-level system: ground and excited electronic states each split by a vibrational quantum of a Raman active mode. Absolute frequencies and their dephasing times of the vibrational modes at ≈590 cm -1 are obtained for the excited as well as the ground electronic state. The vibrational dephasing rate in the excited electronic state is about an order of magnitude faster than that in the ground state, the origin of which is speculated upon.

  20. Real-time vibration measurement by a spatial phase-shifting technique with a tilted holographic interferogram.

    Science.gov (United States)

    Nakadate, S; Isshiki, M

    1997-01-01

    Real-time vibration measurement by a tilted holographic interferogram is presented that utilizes the real-time digital fringe processor of a video signal. Three intensity data sampled at every one-third of the fringe spacing of the tilted fringes are used to calculate the modulation term of the fringe that is a function of a vibration amplitude. A three-dimensional lookup table performs the calculation in a TV repetition rate to give a new fringe profile that contours the vibration amplitude. Vibration modes at the resonant frequencies of a flat speaker were displayed on a monitor as changing the exciting frequency of vibration.

  1. Effects of nuclear vibration on the ionization process of H2+ in ultrashort intense laser field

    International Nuclear Information System (INIS)

    Phan, Ngoc-Loan; Nguyen, Ngoc-Ty; Truong, Tran-Chau

    2015-01-01

    By numerically solving the time-dependent Schrödinger equation, we calculate the ionization probability of a vibrating H 2 + exposed to ultrashort intense laser fields. The results show that the ionization probability increases by time and gets a saturation value. We also find that with some first vibration levels, the ionization probability from a higher vibration level is larger than that from a lower one. However, with higher vibration levels, at a certain level the ionization probability will take maximum and decrease with next levels. (paper)

  2. Vibration-response due to thickness loss on steel plate excited by resonance frequency

    Science.gov (United States)

    Kudus, S. A.; Suzuki, Y.; Matsumura, M.; Sugiura, K.

    2018-04-01

    The degradation of steel structure due to corrosion is a common problem found especially in the marine structure due to exposure to the harsh marine environment. In order to ensure safety and reliability of marine structure, the damage assessment is an indispensable prerequisite for plan of remedial action on damaged structure. The main goal of this paper is to discuss simple vibration measurement on plated structure to give image on overview condition of the monitored structure. The changes of vibration response when damage was introduced in the plate structure were investigated. The damage on plate was simulated in finite element method as loss of thickness section. The size of damage and depth of loss of thickness were varied for different damage cases. The plate was excited with lower order of resonance frequency in accordance estimate the average remaining thickness based on displacement response obtain in the dynamic analysis. Significant reduction of natural frequency and increasing amplitude of vibration can be observed in the presence of severe damage. The vibration analysis summarized in this study can serve as benchmark and reference for researcher and design engineer.

  3. Theory and experiment research for ultra-low frequency maglev vibration sensor

    Science.gov (United States)

    Zheng, Dezhi; Liu, Yixuan; Guo, Zhanshe; Zhao, Xiaomeng; Fan, Shangchun

    2015-10-01

    A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements.

  4. Theory and experiment research for ultra-low frequency maglev vibration sensor

    International Nuclear Information System (INIS)

    Zheng, Dezhi; Liu, Yixuan; Guo, Zhanshe; Fan, Shangchun; Zhao, Xiaomeng

    2015-01-01

    A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements

  5. Theory and experiment research for ultra-low frequency maglev vibration sensor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Dezhi; Liu, Yixuan, E-mail: xuan61x@163.com; Guo, Zhanshe; Fan, Shangchun [School of Instrument Science and Opto-electronics Engineering, Beihang University, Beijing 100191 (China); Zhao, Xiaomeng [Laser Medicine Laboratory, Institute of Biomedical Engineering, Chinese Academy of medical Sciences and Peking Union Medical College, Tianjin 300192 (China)

    2015-10-15

    A new maglev sensor is proposed to measure ultra-low frequency (ULF) vibration, which uses hybrid-magnet levitation structure with electromagnets and permanent magnets as the supporting component, rather than the conventional spring structure of magnetoelectric vibration sensor. Since the lower measurement limit needs to be reduced, the equivalent bearing stiffness coefficient and the equivalent damping coefficient are adjusted by the sensitivity unit structure of the sensor and the closed-loop control system, which realizes both the closed-loop control and the solving algorithms. A simple sensor experimental platform is then assembled based on a digital hardware system, and experimental results demonstrate that the lower measurement limit of the sensor is increased to 0.2 Hz under these experimental conditions, indicating promising results of the maglev sensor for ULF vibration measurements.

  6. A low frequency vibration energy harvester using magnetoelectric laminate composite

    International Nuclear Information System (INIS)

    Ju, Suna; Chae, Song Hee; Choi, Yunhee; Lee, Seungjun; Ji, Chang-Hyeon; Lee, Hyang Woon

    2013-01-01

    In this paper, we present a vibration energy harvester using magnetoelectric laminate composite and a springless spherical permanent magnet as a proof mass. The harvester utilizes a freely movable spherical permanent magnet to transform external vibration into a time varying magnetic field applied to the magnetoelectric transducer. The laminate composite consists of a Ni–Mn–Ga-based MSMA (magnetic shape memory alloy) element and a PZT (lead zirconate titanate) plate. A proof-of-concept harvester has been fabricated and characterized at various input accelerations and frequencies. A maximum open circuit voltage of 1.18 V has been obtained in response to a 3g vibration at 17 Hz with the fabricated device. Moreover, a maximum output voltage of 10.24 V and output power of 4.1 μW have been achieved on a 950 Ω load, when the fabricated energy harvester was mounted on a smartphone and shaken by hand. (paper)

  7. Topology optimization and fabrication of low frequency vibration energy harvesting microdevices

    International Nuclear Information System (INIS)

    Deng, Jiadong; Rorschach, Katherine; Baker, Evan; Sun, Cheng; Chen, Wei

    2015-01-01

    Topological design of miniaturized resonating structures capable of harvesting electrical energy from low frequency environmental mechanical vibrations encounters a particular physical challenge, due to the conflicting design requirements: low resonating frequency and miniaturization. In this paper structural static stiffness to resist undesired lateral deformation is included into the objective function, to prevent the structure from degenerating and forcing the solution to be manufacturable. The rational approximation of material properties interpolation scheme is introduced to deal with the problems of local vibration and instability of the low density area induced by the design dependent body forces. Both density and level set based topology optimization (TO) methods are investigated in their parameterization, sensitivity analysis, and applicability for low frequency energy harvester TO problems. Continuum based variation formulations for sensitivity analysis and the material derivative based shape sensitivity analysis are presented for the density method and the level set method, respectively; and their similarities and differences are highlighted. An external damper is introduced to simulate the energy output of the resonator due to electrical damping and the Rayleigh proportional damping is used for mechanical damping. Optimization results for different scenarios are tested to illustrate the influences of dynamic and static loads. To demonstrate manufacturability, the designs are built to scale using a 3D microfabrication method and assembled into vibration energy harvester prototypes. The fabricated devices based on the optimal results from using different TO techniques are tested and compared with the simulation results. The structures obtained by the level set based TO method require less post-processing before fabrication and the structures obtained by the density based TO method have resonating frequency as low as 100 Hz. The electrical voltage response

  8. The correction of vibration in frequency scanning interferometry based absolute distance measurement system for dynamic measurements

    Science.gov (United States)

    Lu, Cheng; Liu, Guodong; Liu, Bingguo; Chen, Fengdong; Zhuang, Zhitao; Xu, Xinke; Gan, Yu

    2015-10-01

    Absolute distance measurement systems are of significant interest in the field of metrology, which could improve the manufacturing efficiency and accuracy of large assemblies in fields such as aircraft construction, automotive engineering, and the production of modern windmill blades. Frequency scanning interferometry demonstrates noticeable advantages as an absolute distance measurement system which has a high precision and doesn't depend on a cooperative target. In this paper , the influence of inevitable vibration in the frequency scanning interferometry based absolute distance measurement system is analyzed. The distance spectrum is broadened as the existence of Doppler effect caused by vibration, which will bring in a measurement error more than 103 times bigger than the changes of optical path difference. In order to decrease the influence of vibration, the changes of the optical path difference are monitored by a frequency stabilized laser, which runs parallel to the frequency scanning interferometry. The experiment has verified the effectiveness of this method.

  9. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Nian; Yang, Jin, E-mail: yangjin@cqu.edu.cn; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping [Department of Optoelectronic Engineering, Chongqing University, Chongqing 400044 (China)

    2016-01-15

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.

  10. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies

    Science.gov (United States)

    Zhao, Nian; Yang, Jin; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping

    2016-01-01

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.

  11. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies

    International Nuclear Information System (INIS)

    Zhao, Nian; Yang, Jin; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping

    2016-01-01

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life

  12. Three-dimensional piezoelectric vibration energy harvester using spiral-shaped beam with triple operating frequencies.

    Science.gov (United States)

    Zhao, Nian; Yang, Jin; Yu, Qiangmo; Zhao, Jiangxin; Liu, Jun; Wen, Yumei; Li, Ping

    2016-01-01

    This work has demonstrated a novel piezoelectric energy harvester without a complex structure and appended component that is capable of scavenging vibration energy from arbitrary directions with multiple resonant frequencies. In this harvester, a spiral-shaped elastic thin beam instead of a traditional thin cantilever beam was adopted to absorb external vibration with arbitrary direction in three-dimensional (3D) spaces owing to its ability to bend flexibly and stretch along arbitrary direction. Furthermore, multiple modes in the elastic thin beam contribute to a possibility to widen the working bandwidth with multiple resonant frequencies. The experimental results show that the harvester was capable of scavenging the vibration energy in 3D arbitrary directions; they also exhibited triple power peaks at about 16 Hz, 21 Hz, and 28 Hz with the powers of 330 μW, 313 μW, and 6 μW, respectively. In addition, human walking and water wave energies were successfully converted into electricity, proving that our harvester was practical to scavenge the time-variant or multi-directional vibration energies in our daily life.

  13. Bi-resonant structure with piezoelectric PVDF films for energy harvesting from random vibration sources at low frequency

    DEFF Research Database (Denmark)

    Liang, Shanshan; Crovetto, Andrea; Peng, Zhuoteng

    2016-01-01

    and experiments with piezoelectric elements show that the energy harvesting device with the bi-resonant structure can generate higher power output than that of the sum of the two separate devices from random vibration sources at low frequency, and hence significantly improves the vibration-to- electricity......This paper reports on a bi-resonant structure of piezoelectric PVDF films energy harvester (PPEH), which consists of two cantilevers with resonant frequencies of 15 Hz and 22 Hz. With increased acceleration, the vibration amplitudes of the two cantilever-mass structures are increased and collision...

  14. Dependence of Moessbauer resonance intensities on vibrational lattice anisotropy in case of an axial electric field gradient

    International Nuclear Information System (INIS)

    Friedt, J.M.

    1976-01-01

    The change in the hyperfine line intensities is discussed for various Moessbauer transitions in cases involving axial vibrational lattice anisotropy and axial electric field gradient at the resonant nucleus. The change in the relative intensities of the spectral components has been calculed numerically for the different types of Moessbauer transitions. Polynomial expansions are given to describe the functional dependence of the relative intensities on the magnitude of the vibration anisotropy. They may be used to extract the relevant parameters from experimental data without requiring the numerical integrations implied in the description of the Goldanskii-Karyagin effect [fr

  15. Molecular vibration-activity relationship in the agonism of adenosine receptors.

    Science.gov (United States)

    Chee, Hyun Keun; Oh, S June

    2013-12-01

    The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.

  16. Trends in Northern Hemisphere surface cyclone frequency and intensity

    Science.gov (United States)

    McCabe, G.J.; Clark, M.P.; Serreze, Mark C.

    2001-01-01

    One of the hypothesized effects of global warming from increasing concentrations of greenhouse gases is a change in the frequency and/or intensity of extratropical cyclones. In this study, winter frequencies and intensities of extratropical cyclones in the Northern Hemisphere for the period 1959-97 are examined to determine if identifiable trends are occurring. Results indicate a statistically significant decrease in midlatitude cyclone frequency and a significant increase in high-latitude cyclone frequency. In addition, storm intensity has increased in both the high and midlatitudes. The changes in storm frequency correlate with changes in winter Northern Hemisphere temperature and support hypotheses that global warming may result in a northward shift of storm tracks in the Northern Hemisphere.

  17. Comparative Study of Time-Frequency Decomposition Techniques for Fault Detection in Induction Motors Using Vibration Analysis during Startup Transient

    Directory of Open Access Journals (Sweden)

    Paulo Antonio Delgado-Arredondo

    2015-01-01

    Full Text Available Induction motors are critical components for most industries and the condition monitoring has become necessary to detect faults. There are several techniques for fault diagnosis of induction motors and analyzing the startup transient vibration signals is not as widely used as other techniques like motor current signature analysis. Vibration analysis gives a fault diagnosis focused on the location of spectral components associated with faults. Therefore, this paper presents a comparative study of different time-frequency analysis methodologies that can be used for detecting faults in induction motors analyzing vibration signals during the startup transient. The studied methodologies are the time-frequency distribution of Gabor (TFDG, the time-frequency Morlet scalogram (TFMS, multiple signal classification (MUSIC, and fast Fourier transform (FFT. The analyzed vibration signals are one broken rotor bar, two broken bars, unbalance, and bearing defects. The obtained results have shown the feasibility of detecting faults in induction motors using the time-frequency spectral analysis applied to vibration signals, and the proposed methodology is applicable when it does not have current signals and only has vibration signals. Also, the methodology has applications in motors that are not fed directly to the supply line, in such cases the analysis of current signals is not recommended due to poor current signal quality.

  18. Peculiarities of the Third Natural Frequency Vibrations of a Cantilever for the Improvement of Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Vytautas Ostasevicius

    2015-05-01

    Full Text Available This paper focuses on several aspects extending the dynamical efficiency of a cantilever beam vibrating in the third mode. A few ways of producing this mode stimulation, namely vibro-impact or forced excitation, as well as its application for energy harvesting devices are proposed. The paper presents numerical and experimental analyses of novel structural dynamics effects along with an optimal configuration of the cantilever beam. The peculiarities of a cantilever beam vibrating in the third mode are related to the significant increase of the level of deformations capable of extracting significant additional amounts of energy compared to the conventional harvester vibrating in the first mode. Two types of a piezoelectric vibrating energy harvester (PVEH prototype are analysed in this paper: the first one without electrode segmentation, while the second is segmented using electrode segmentation at the strain nodes of the third vibration mode to achieve effective operation at the third resonant frequency. The results of this research revealed that the voltage generated by any segment of the segmented PVEH prototype excited at the third resonant frequency demonstrated a 3.4–4.8-fold increase in comparison with the non-segmented prototype. Simultaneously, the efficiency of the energy harvester prototype also increased at lower resonant frequencies from 16% to 90%. The insights presented in the paper may serve for the development and fabrication of advanced piezoelectric energy harvesters which would be able to generate a considerably increased amount of electrical energy independently of the frequency of kinematical excitation.

  19. Franck-Condon fingerprinting of vibration-tunneling spectra.

    Science.gov (United States)

    Berrios, Eduardo; Sundaradevan, Praveen; Gruebele, Martin

    2013-08-15

    We introduce Franck-Condon fingerprinting as a method for assigning complex vibration-tunneling spectra. The B̃ state of thiophosgene (SCCl2) serves as our prototype. Despite several attempts, assignment of its excitation spectrum has proved difficult because of near-degenerate vibrational frequencies, Fermi resonance between the C-Cl stretching mode and the Cl-C-Cl bending mode, and large tunneling splittings due to the out-of-plane umbrella mode. Hence, the spectrum has never been fitted to an effective Hamiltonian. Our assignment approach replaces precise frequency information with intensity information, eliminating the need for double resonance spectroscopy or combination differences, neither of which have yielded a full assignment thus far. The dispersed fluorescence spectrum of each unknown vibration-tunneling state images its character onto known vibrational progressions in the ground state. By using this Franck-Condon fingerprint, we were able to determine the predominant character of several vibration-tunneling states and assign them; in other cases, the fingerprinting revealed that the states are strongly mixed and cannot be characterized with a simple normal mode assignment. The assigned transitions from vibration-tunneling wave functions that were not too strongly mixed could be fitted within measurement uncertainty by an effective vibration-tunneling Hamiltonian. A fit of all observed vibration-tunneling states will require a full resonance-tunneling Hamiltonian.

  20. The vibrational behaviour of the generator support structure for Koeberg nuclear power station at high frequencies

    International Nuclear Information System (INIS)

    Lee, D.E.

    1988-06-01

    The vibrational behaviour of the generator support structure at Koeberg nuclear power station at frequencies primarily in the region of 80 Hz to 110 Hz was examined. The effect of soil-structure interaction and the change in stiffness of the foundation soil was investigated. Vibration tests were performed on the generator support structure and the results were compared with a theoretical finite element analysis of the structure. By varying the soil-cement foundation stiffness it was possible to demonstrate the change in dynamic behaviour of the structure in the higher frequency band 80 Hz to 110 Hz. Comment has been made on the design code DIN 4024 in view of the findings of this thesis. It was concluded that the empirical rules regarding the inclusion of the foundation in an analysis specified by the code do not cover all cases and greater cognisance of the effect of the foundation stiffness on the vibration behaviour of such machine foundations is necessary. Obvious machine frequencies higher than the operational frequencies should be analysed where it is considered necessary. 24 refs., 25 tabs., 83 figs

  1. Vibrational spectroscopic study of fluticasone propionate

    Science.gov (United States)

    Ali, H. R. H.; Edwards, H. G. M.; Kendrick, J.; Scowen, I. J.

    2009-03-01

    Fluticasone propionate is a synthetic glucocorticoid with potent anti-inflammatory activity that has been used effectively in the treatment of chronic asthma. The present work reports a vibrational spectroscopic study of fluticasone propionate and gives proposed molecular assignments on the basis of ab initio calculations using BLYP density functional theory with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation. Several spectral features and band intensities are explained. This study generated a library of information that can be employed to aid the process monitoring of fluticasone propionate.

  2. Low frequency noise and air vibration generated by a simple cycle gas turbine installation

    Energy Technology Data Exchange (ETDEWEB)

    Giesbrecht, C.; Hertil, S. [ATCO Noise Management, Calgary, AB (Canada)

    2005-07-01

    Low-frequency noise refers to infrasound whose frequency is lower than the minimum human audible frequency of about 20 Hz. Recently, there have been serious complaints on noise pollution in the frequency range of 1-100 Hz. This presentation outlined ASHRAE noise criteria regions and discussed human perceptions to vibration. It also presented methods that ATCO used for measuring noise at a simple gas turbine installation, inside the site at the administration buildings, at the paths of vibration and noise propagation, and at noise sensitive receptors. A 70 dBC at the closes noise-sensitive receptor was used as a noise limit to minimize annoyance. In addition, 96 dBC was measured at 400 feet. It was noted that reducing the C-weighted sound level depends on reducing the stack noise emissions in the 16 and 31.5 band levels. ATCO evaluated silencer designs and recommended reactive silencers to achieve a 10 dB reduction in noise emitted by the 3 exhaust stacks. 6 figs.

  3. Molecular Vibration-Activity Relationship in the Agonism of Adenosine Receptors

    Directory of Open Access Journals (Sweden)

    Hyun Keun Chee

    2013-12-01

    Full Text Available The molecular vibration-activity relationship in the receptor-ligand interaction of adenosine receptors was investigated by structure similarity, molecular vibration, and hierarchical clustering in a dataset of 46 ligands of adenosine receptors. The resulting dendrogram was compared with those of another kind of fingerprint or descriptor. The dendrogram result produced by corralled intensity of molecular vibrational frequency outperformed four other analyses in the current study of adenosine receptor agonism and antagonism. The tree that was produced by clustering analysis of molecular vibration patterns showed its potential for the functional classification of adenosine receptor ligands.

  4. Amplitude-cyclic frequency decomposition of vibration signals for bearing fault diagnosis based on phase editing

    Science.gov (United States)

    Barbini, L.; Eltabach, M.; Hillis, A. J.; du Bois, J. L.

    2018-03-01

    In rotating machine diagnosis different spectral tools are used to analyse vibration signals. Despite the good diagnostic performance such tools are usually refined, computationally complex to implement and require oversight of an expert user. This paper introduces an intuitive and easy to implement method for vibration analysis: amplitude cyclic frequency decomposition. This method firstly separates vibration signals accordingly to their spectral amplitudes and secondly uses the squared envelope spectrum to reveal the presence of cyclostationarity in each amplitude level. The intuitive idea is that in a rotating machine different components contribute vibrations at different amplitudes, for instance defective bearings contribute a very weak signal in contrast to gears. This paper also introduces a new quantity, the decomposition squared envelope spectrum, which enables separation between the components of a rotating machine. The amplitude cyclic frequency decomposition and the decomposition squared envelope spectrum are tested on real word signals, both at stationary and varying speeds, using data from a wind turbine gearbox and an aircraft engine. In addition a benchmark comparison to the spectral correlation method is presented.

  5. Influence of Traffic Vehicles Against Ground Fundamental Frequency Prediction using Ambient Vibration Technique

    Science.gov (United States)

    Kamarudin, A. F.; Noh, M. S. Md; Mokhatar, S. N.; Anuar, M. A. Mohd; Ibrahim, A.; Ibrahim, Z.; Daud, M. E.

    2018-04-01

    Ambient vibration (AV) technique is widely used nowadays for ground fundamental frequency prediction. This technique is easy, quick, non-destructive, less operator required and reliable result. The input motions of ambient vibration are originally collected from surrounding natural and artificial excitations. But, careful data acquisition controlled must be implemented to reduce the intrusion of short period noise that could imply the quality of frequency prediction of an investigated site. In this study, investigation on the primary noise intrusion under peak (morning, afternoon and evening) and off peak (early morning) traffic flows (only 8 meter from sensor to road shoulder) against the stability and quality of ground fundamental frequency prediction were carried out. None of specific standard is available for AV data acquisition and processing. Thus, some field and processing parameters recommended by previous studies and guideline were considered. Two units of 1 Hz tri-axial seismometer sensor were closely positioned in front of the main entrance Universiti Tun Hussein Onn Malaysia. 15 minutes of recording length were taken during peak and off peak periods of traffic flows. All passing vehicles were counted and grouped into four classes. Three components of ambient vibration time series recorded in the North-South: NS, East-West: EW and vertical: UD directions were automatically computed into Horizontal to Vertical Spectral Ratio (HVSR), by using open source software of GEOPSY for fundamental ground frequency, Fo determination. Single sharp peak pattern of HVSR curves have been obtained at peak frequencies between 1.33 to 1.38 Hz which classified under soft to dense soil classification. Even identical HVSR curves pattern with close frequencies prediction were obtained under both periods of AV measurement, however the total numbers of stable and quality windows selected for HVSR computation were significantly different but both have satisfied the requirement

  6. Nonlinear vibration behaviors of suspended cables under two-frequency excitation with temperature effects

    Science.gov (United States)

    Zhao, Yaobing; Huang, Chaohui; Chen, Lincong; Peng, Jian

    2018-03-01

    The aim of this paper is to investigate temperature effects on the nonlinear vibration behaviors of suspended cables under two-frequency excitation. For this purpose, two combination and simultaneous resonances are chosen and studied in detail. First of all, based on the assumptions of the temperature effects, the partial differential equations of the in-plane and out-of-plane motions with thermal effects under multi-frequency excitations are obtained. The Galerkin method is adopted to discretize the nonlinear dynamic equations, and the single-mode planar discretization is considered. Then, in the absence of the primary and internal resonances, the frequency response equations are obtained by using the multiple scales method. The stability analyses are conducted via investigating the nature of the singular points of equations. After that, temperature effects on nonlinear vibration characteristics of the first symmetric mode are studied. Parametric investigations of temperature effects on corresponding non-dimensional factors and coefficients of linear and nonlinear terms are performed. Numerical results are presented to show the temperature effects via the frequency-response curves and detuning-phase curves of four different sag-to-span ratios. It is found out that effects of temperature variations would lead to significant quantitative and/or qualitative changes of the nonlinear vibration properties, and these effects are closely related to the sag-to-span ratio and the degree of the temperature variation. Specifically, the softening/hardening-type spring behaviors, the response amplitude, the range of the resonance, the intersection and number of branches, the number and phase of the steady-state solutions are all affected by the temperature changes.

  7. Correlation analysis of motor current and chatter vibration in grinding using complex continuous wavelet coherence

    International Nuclear Information System (INIS)

    Liu, Yao; Wang, Xiufeng; Lin, Jing; Zhao, Wei

    2016-01-01

    Motor current is an emerging and popular signal which can be used to detect machining chatter with its multiple advantages. To achieve accurate and reliable chatter detection using motor current, it is important to make clear the quantitative relationship between motor current and chatter vibration, which has not yet been studied clearly. In this study, complex continuous wavelet coherence, including cross wavelet transform and wavelet coherence, is applied to the correlation analysis of motor current and chatter vibration in grinding. Experimental results show that complex continuous wavelet coherence performs very well in demonstrating and quantifying the intense correlation between these two signals in frequency, amplitude and phase. When chatter occurs, clear correlations in frequency and amplitude in the chatter frequency band appear and the phase difference of current signal to vibration signal turns from random to stable. The phase lead of the most correlated chatter frequency is the largest. With the further development of chatter, the correlation grows up in intensity and expands to higher order chatter frequency band. The analyzing results confirm that there is a consistent correlation between motor current and vibration signals in the grinding chatter process. However, to achieve accurate and reliable chatter detection using motor current, the frequency response bandwidth of current loop of the feed drive system must be wide enough to response chatter effectively. (paper)

  8. Capturing inhomogeneous broadening of the -CN stretch vibration in a Langmuir monolayer with high-resolution spectra and ultrafast vibrational dynamics in sum-frequency generation vibrational spectroscopy (SFG-VS)

    Science.gov (United States)

    Velarde, Luis; Wang, Hong-fei

    2013-08-01

    While in principle the frequency-domain and time-domain spectroscopic measurements should generate identical information for a given molecular system, the inhomogeneous character of surface vibrations in sum-frequency generation vibrational spectroscopy (SFG-VS) studies has only been studied with time-domain SFG-VS by mapping the decay of the vibrational polarization using ultrafast lasers, this due to the lack of SFG vibrational spectra with high enough spectral resolution and accurate enough lineshape. Here, with the recently developed high-resolution broadband SFG-VS (HR-BB-SFG-VS) technique, we show that the inhomogeneous lineshape can be obtained in the frequency-domain for the anchoring CN stretch of the 4-n-octyl-4'-cyanobiphenyl (8CB) Langmuir monolayer at the air-water interface, and that an excellent agreement with the time-domain SFG free-induction-decay can be established. We found that the 8CB CN stretch spectrum consists of a single peak centered at 2234.00 ± 0.01 cm-1 with a total linewidth of 10.9 ± 0.3 cm-1 at half maximum. The Lorentzian contribution accounts only for 4.7 ± 0.4 cm-1 to this width and the Gaussian (inhomogeneous) broadening for as much as 8.1 ± 0.2 cm-1. Polarization analysis of the -CN spectra showed that the -CN group is tilted 57° ± 2° from the surface normal. The large heterogeneity in the -CN spectrum is tentatively attributed to the -CN group interactions with the interfacial water molecules penetrated/accommodated into the 8CB monolayer, a unique phenomenon for the nCB Langmuir monolayers reported previously.

  9. Nonlinear Microstructured Material to Reduce Noise and Vibrations at Low Frequencies

    International Nuclear Information System (INIS)

    Lavazec, Deborah; Cumunel, Gwendal; Duhamel, Denis; Soize, Christian; Batou, Anas

    2016-01-01

    At low frequencies, for which the wavelengths are wide, the acoustic waves and the mechanical vibrations cannot easily be reduced in the structures at macroscale by using dissipative materials, contrarily to the middle- and high-frequency ranges. The final objective of this work is to reduce the vibrations and the induced noise on a broad low-frequency band by using a microstructured material by inclusions that are randomly arranged in the material matrix. The dynamical regimes of the inclusions will be imposed in the nonlinear domain in order that the energy be effectively pumped over a broad frequency band around the resonance frequency, due to the nonlinearity. The first step of this work is to design and to analyze the efficiency of an inclusion, which is made up of a hollow frame including a point mass centered on a beam. This inclusion is designed in order to exhibit nonlinear geometric effects in the low-frequency band that is observed. For this first step, the objective is to develop the simplest mechanical model that has the capability to roughly predict the experimental results that are measured. The second step, which is not presented in the paper, will consist in developing a more sophisticated nonlinear dynamical model of the inclusion. In this paper, devoted to the first step, it is proved that the nonlinearity induces an attenuation on a broad frequency band around the resonance, contrarily to its linear behavior for which the attenuation is only active in a narrow frequency band around the resonance. We will present the design in terms of geometry, dimension and materials for the inclusion, the experimental manufacturing of this system realized with a 3D printing system, and the experimental measures that have been performed. We compare the prevision given by the stochastic computational model with the measurements. The results obtained exhibit the physical attenuation over a broad low-frequency band, which were expected. (paper)

  10. High-frequency, high-intensity photoionization

    Science.gov (United States)

    Reiss, H. R.

    1996-02-01

    Two analytical methods for computing ionization by high-frequency fields are compared. Predicted ionization rates compare well, but energy predictions for the onset of ionization differ radically. The difference is shown to arise from the use of a transformation in one of the methods that alters the zero from which energy is measured. This alteration leads to an apparent energy threshold for ionization that can, especially in the stabilization regime, differ strongly from the laboratory measurement. It is concluded that channel closings in intense-field ionization can occur at high as well as low frequencies. It is also found that the stabilization phenomenon at high frequencies, very prominent for hydrogen, is absent in a short-range potential.

  11. Building Modern Vibration Diagnostics Systems Based on the Frequency-Time Transformations of A Measured Signal

    Directory of Open Access Journals (Sweden)

    Yasoveev Vasikh

    2016-01-01

    Full Text Available Basic methods of analysis of vibration transducers signals were reviewed. Continuous wavelet transform, being a time-frequency transform, was found to be an advanced mathematical tool for analysis of vibration signals. Experimental studies revealed obvious changes in the continuous wavelet transform spectrum depending on the existing defects. A method for detection and identification of technological violations based on the analysis of CWT spectrum components and normalized correlation coefficient was suggested. In accordance with the suggested method software for vibration diagnostics was developed.

  12. Vibration mode and vibration shape under excitation of a three phase model transformer core

    Science.gov (United States)

    Okabe, Seiji; Ishigaki, Yusuke; Omura, Takeshi

    2018-04-01

    Structural vibration characteristics and vibration shapes under three-phase excitation of a archetype transformer core were investigated to consider their influences on transformer noise. Acoustic noise and vibration behavior were measured in a three-limb model transformer core. Experimental modal analysis by impact test was performed. The vibration shapes were measured by a laser scanning vibrometer at different exciting frequencies. Vibration amplitude of the core in out-of-plane direction were relatively larger than those in other two in-plane directions. It was consistent with the result that the frequency response function of the core in out-of-plane direction was larger by about 20 dB or more than those in in-plane directions. There were many vibration modes having bending deformation of limbs in out-of-plane direction. The vibration shapes of the core when excited at 50 Hz and 60 Hz were almost the same because the fundamental frequencies of the vibration were not close to the resonance frequencies. When excitation frequency was 69 Hz which was half of one of the resonance frequencies, the vibration shape changed to the one similar to the resonance vibration mode. Existence of many vibration modes in out-of-plane direction of the core was presumed to be a reason why frequency characteristics of magnetostriction and transformer noise do not coincide.

  13. Vibration sensor data denoising using a time-frequency manifold for machinery fault diagnosis.

    Science.gov (United States)

    He, Qingbo; Wang, Xiangxiang; Zhou, Qiang

    2013-12-27

    Vibration sensor data from a mechanical system are often associated with important measurement information useful for machinery fault diagnosis. However, in practice the existence of background noise makes it difficult to identify the fault signature from the sensing data. This paper introduces the time-frequency manifold (TFM) concept into sensor data denoising and proposes a novel denoising method for reliable machinery fault diagnosis. The TFM signature reflects the intrinsic time-frequency structure of a non-stationary signal. The proposed method intends to realize data denoising by synthesizing the TFM using time-frequency synthesis and phase space reconstruction (PSR) synthesis. Due to the merits of the TFM in noise suppression and resolution enhancement, the denoised signal would have satisfactory denoising effects, as well as inherent time-frequency structure keeping. Moreover, this paper presents a clustering-based statistical parameter to evaluate the proposed method, and also presents a new diagnostic approach, called frequency probability time series (FPTS) spectral analysis, to show its effectiveness in fault diagnosis. The proposed TFM-based data denoising method has been employed to deal with a set of vibration sensor data from defective bearings, and the results verify that for machinery fault diagnosis the method is superior to two traditional denoising methods.

  14. Low frequency vibration approach for assessing performance of wood floor systems

    Science.gov (United States)

    Xiping Wang; Robert J. Ross; Michael O. Hunt; John R. Erickson; John W. Forsman

    2005-01-01

    The primary means of inspecting buildings and other structures is to evaluate each structure member individually. This is a time-consuming and expensive process, particularly if sheathing or other covering materials must be removed to access the structural members. The objective of this study was to determine if a low frequency vibration method could be used to...

  15. The vibrating reed frequency meter : digital investigation of an early cochlear model

    NARCIS (Netherlands)

    Bell, Andrew; Wit, Hero P.

    2015-01-01

    The vibrating reed frequency meter, originally employed by Bekesy and later by Wilson as a cochlear model, uses a set of tuned reeds to represent the cochlea's graded bank of resonant elements and an elastic band threaded between them to provide nearest-neighbour coupling. Here the system,

  16. Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of 4-chlorobenzothioamide

    Science.gov (United States)

    Çırak, Çağrı; Sert, Yusuf; Ucun, Fatih

    2013-09-01

    In the present work, the experimental and theoretical vibrational spectra of 4-chlorobenzothioamide were investigated. The FT-IR (400-4000 cm-1) and μ-Raman spectra (100-4000 cm-1) of 4-chlorobenzothioamide in the solid phase were recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared and Raman intensities of the title molecule in the ground state were calculated using ab initio Hartree-Fock and density functional theory (B3LYP) methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and the theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 4-chlorobenzothioamide was also simulated to evaluate the effect of intermolecular hydrogen bonding on the vibrational frequencies. It was observed that the Nsbnd H stretching modes shifted to lower frequencies, while the in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular Nsbnd H⋯S hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

  17. Effect of grazing frequency and intensity on Lolium perenne L ...

    African Journals Online (AJOL)

    ) system. Low frequency, low intensity grazing produced lower CDMD and herbage N levels than higher grazing frequencies and intensities. These differences were, however, generally small. Overall, levels of herbage digestibility (estimated ...

  18. Three-Dimensional Vibration Isolator for Suppressing High-Frequency Responses for Sage III Contamination Monitoring Package (CMP)

    Science.gov (United States)

    Li, Y.; Cutright, S.; Dyke, R.; Templeton, J.; Gasbarre, J.; Novak, F.

    2015-01-01

    The Stratospheric Aerosol and Gas Experiment (SAGE) III - International Space Station (ISS) instrument will be used to study ozone, providing global, long-term measurements of key components of the Earth's atmosphere for the continued health of Earth and its inhabitants. SAGE III is launched into orbit in an inverted configuration on SpaceX;s Falcon 9 launch vehicle. As one of its four supporting elements, a Contamination Monitoring Package (CMP) mounted to the top panel of the Interface Adapter Module (IAM) box experiences high-frequency response due to structural coupling between the two structures during the SpaceX launch. These vibrations, which were initially observed in the IAM Engineering Development Unit (EDU) test and later verified through finite element analysis (FEA) for the SpaceX launch loads, may damage the internal electronic cards and the Thermoelectric Quartz Crystal Microbalance (TQCM) sensors mounted on the CMP. Three-dimensional (3D) vibration isolators were required to be inserted between the CMP and IAM interface in order to attenuate the high frequency vibrations without resulting in any major changes to the existing system. Wire rope isolators were proposed as the isolation system between the CMP and IAM due to the low impact to design. Most 3D isolation systems are designed for compression and roll, therefore little dynamic data was available for using wire rope isolators in an inverted or tension configuration. From the isolator FEA and test results, it is shown that by using the 3D wire rope isolators, the CMP high-frequency responses have been suppressed by several orders of magnitude over a wide excitation frequency range. Consequently, the TQCM sensor responses are well below their qualification environments. It is indicated that these high-frequency responses due to the typical instrument structural coupling can be significantly suppressed by a vibration passive control using the 3D vibration isolator. Thermal and contamination

  19. Measurement of Mechatronic Property of Biological Gel with Micro-Vibrating Electrode at Ultrasonic Frequency

    Directory of Open Access Journals (Sweden)

    Shigehiro Hashimoto

    2008-10-01

    Full Text Available A measurement system has been designed with a micro-vibrating electrode at ultrasonic frequency to measure local impedance of biological gel in vitro. The designed system consists of two electrodes, where one of the electrodes vibrates with a piezoelectric actuator. The component of variation at impedance between two electrodes with vibration of one electrode is analyzed at the corresponding spectrum. The manufactured system was applied to measure impedance of a physiological saline solution, a potassium chloride solution, a dextran aqueous solution, and an egg. The experimental results show that the designed system is effective to measure local mechatronic property of biological gel.

  20. The Health Effects and Keep Down of Whole Body Vibration

    Directory of Open Access Journals (Sweden)

    Funda Sevencan

    2014-04-01

    Full Text Available Vibration was defined that oscillation of the body according to the reference point. The tools that are used in industry and are the source of vibration cause diseases. For this reason, the vibration has been one of the factors that affect the health and of the most widely researched in the field of ergonomics. The perceived intensity and health effects of vibration depend on the vibration frequency, intensity, direction, acceleration, duration of exposure, vibration affects the region, age, gender, posture, distance from the source person, activity, time of day and the person\\s overall health condition. The one of the most common health effects of whole body vibration is impact on musculoskeletal system. In many studies, indicated that whole-body vibration effect waist, back, shoulder and neck especially. There were varied studies that hormone levels were not changed as well there were varied studies that hormone levels were increased or decreased. There were varied studies about the digestive and circulatory system. In these studies, digestive system complaints, peptic ulcer, gastritis, varicose veins and hemorrhoids were determined frequently. For protection the health effect of vibration, Directives of the European Commission, Turkish Standards, Assessment and Management of Environmental Noise and Vibration Regulations were published. For the control of vibration are need technical and medical measures and education [TAF Prev Med Bull 2014; 13(2.000: 177-186

  1. Theoretical study of the changes in the vibrational characteristics arising from the hydrogen bonding between Vitamin C ( L-ascorbic acid) and H 2O

    Science.gov (United States)

    Dimitrova, Yordanka

    2006-02-01

    The vibrational characteristics (vibrational frequencies, infrared intensities and Raman activities) for the hydrogen-bonded system of Vitamin C ( L-ascorbic acid) with five water molecules have been predicted using ab initio SCF/6-31G(d, p) calculations and DFT (BLYP) calculations with 6-31G(d, p) and 6-31++G(d, p) basis sets. The changes in the vibrational characteristics from free monomers to a complex have been calculated. The ab initio and BLYP calculations show that the complexation between Vitamin C and five water molecules leads to large red shifts of the stretching vibrations for the monomer bonds involved in the hydrogen bonding and very strong increase in their IR intensity. The predicted frequency shifts for the stretching vibrations from Vitamin C taking part in the hydrogen bonding are up to -508 cm -1. The magnitude of the wavenumber shifts is indicative of relatively strong OH···H hydrogen-bonded interactions. In the same time the IR intensity and Raman activity of these vibrations increase upon complexation. The IR intensity increases dramatically (up to 12 times) and Raman activity increases up to three times. The ab initio and BLYP calculations show, that the symmetric OH vibrations of water molecules are more sensitive to the complexation. The hydrogen bonding leads to very large red shifts of these vibrations and very strong increase in their IR intensity. The asymmetric OH stretching vibrations of water, free from hydrogen bonding are less sensitive to the complexation than the hydrogen-bonded symmetric O sbnd H stretching vibrations. The increases of the IR intensities for these vibrations are lower and red shifts are negligible.

  2. Hyperfine-resolved transition frequency list of fundamental vibration bands of H35Cl and H37Cl

    Science.gov (United States)

    Iwakuni, Kana; Sera, Hideyuki; Abe, Masashi; Sasada, Hiroyuki

    2014-12-01

    Sub-Doppler resolution spectroscopy of the fundamental vibration bands of H35Cl and H37Cl has been carried out from 87.1 to 89.9 THz. We have determined the absolute transition frequencies of the hyperfine-resolved R(0) to R(4) transitions with a typical uncertainty of 10 kHz. We have also yielded six molecular constants for each isotopomer in the vibrational excited state, which reproduce the determined frequencies with a standard deviation of about 10 kHz.

  3. Using frequency response functions to manage image degradation from equipment vibration in the Daniel K. Inouye Solar Telescope

    Science.gov (United States)

    McBride, William R.; McBride, Daniel R.

    2016-08-01

    The Daniel K Inouye Solar Telescope (DKIST) will be the largest solar telescope in the world, providing a significant increase in the resolution of solar data available to the scientific community. Vibration mitigation is critical in long focal-length telescopes such as the Inouye Solar Telescope, especially when adaptive optics are employed to correct for atmospheric seeing. For this reason, a vibration error budget has been implemented. Initially, the FRFs for the various mounting points of ancillary equipment were estimated using the finite element analysis (FEA) of the telescope structures. FEA analysis is well documented and understood; the focus of this paper is on the methods involved in estimating a set of experimental (measured) transfer functions of the as-built telescope structure for the purpose of vibration management. Techniques to measure low-frequency single-input-single-output (SISO) frequency response functions (FRF) between vibration source locations and image motion on the focal plane are described. The measurement equipment includes an instrumented inertial-mass shaker capable of operation down to 4 Hz along with seismic accelerometers. The measurement of vibration at frequencies below 10 Hz with good signal-to-noise ratio (SNR) requires several noise reduction techniques including high-performance windows, noise-averaging, tracking filters, and spectral estimation. These signal-processing techniques are described in detail.

  4. Nonlinear generation of non-acoustic modes by low-frequency sound in a vibrationally relaxing gas

    International Nuclear Information System (INIS)

    Perelomova, A.

    2010-01-01

    Two dynamic equations referring to a weakly nonlinear and weakly dispersive flow of a gas in which molecular vibrational relaxation takes place, are derived. The first one governs an excess temperature associated with the thermal mode, and the second one describes variations in vibrational energy. Both quantities refer to non-wave types of gas motion. These variations are caused by the nonlinear transfer of acoustic energy into thermal mode and internal vibrational degrees of freedom of a relaxing gas. The final dynamic equations are instantaneous; they include a quadratic nonlinear acoustic source, reflecting the nonlinear character of interaction of low-frequency acoustic and non-acoustic motions of the fluid. All types of sound, periodic or aperiodic, may serve as an acoustic source of both phenomena. The low-frequency sound is considered in this study. Some conclusions about temporal behavior of non-acoustic modes caused by periodic and aperiodic sound are made. Under certain conditions, acoustic cooling takes place instead of heating. (author)

  5. Task-specific recruitment of motor units for vibration damping.

    Science.gov (United States)

    Wakeling, James M; Liphardt, Anna-Maria

    2006-01-01

    Vibrations occur within the soft tissues of the lower extremities due to the heel-strike impact during walking. Increases in muscle activity in the lower extremities result in increased damping to reduce this vibration. The myoelectric intensity spectra were compared using principal component analysis from the tibialis anterior and lateral gastrocnemius of 40 subjects walking with different shoe conditions. The soft insert condition resulted in a significant, simultaneous increase in muscle activity with a shift to higher myoelectric frequencies in the period 0-60 ms after heel-strike which is the period when the greater vibration damping occurred. These increases in myoelectric frequency match the spectral patterns which indicate increases in recruitment of faster motor units. It is concluded that fast motor units are recruited during the task of damping the soft-tissue resonance that occurs following heel-strike.

  6. Conformational, vibrational, NMR and DFT studies of N-methylacetanilide.

    Science.gov (United States)

    Arjunan, V; Santhanam, R; Rani, T; Rosi, H; Mohan, S

    2013-03-01

    A detailed conformational, vibrational, NMR and DFT studies of N-methylacetanilide have been carried out. In DFT, B3LYP method have been used with 6-31G(**), 6-311++G(**) and cc-pVTZ basis sets. The vibrational frequencies were calculated resulting in IR and Raman frequencies together with intensities and Raman depolarisation ratios. The dipole moment derivatives were computed analytically. Owing to the complexity of the molecule, the potential energy distributions of the vibrational modes of the compound are also calculated. Isoelectronic molecular electrostatic potential surface (MEP) and electron density surface were examined. (1)H and (13)C NMR isotropic chemical shifts were calculated and the assignments made are compared with the experimental values. The energies of important MO's of the compound were also determined from TD-DFT method. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Selective probe of the morphology and local vibrations at carbon nanoasperities

    Energy Technology Data Exchange (ETDEWEB)

    Fujimori, Toshihiko; Endo, Morinobu; Kaneko, Katsumi [Research Center for Exotic Nanocarbons (JST), Shinshu University, 4-17-1, Wakasato, Nagano-city 380-8553 (Japan); Urita, Koki; Moriguchi, Isamu [Department of Applied Chemistry, Faculty of Engineering, Nagasaki University, 1-14 Bunkyo-machi, Nagasaki-shi, Nagasaki 852-8521 (Japan); Tomanek, David [Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824 (United States); Ohba, Tomonori [Department of Chemistry, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

    2012-02-14

    We introduce a way to selectively probe local vibration modes at nanostructured asperities such as tips of carbon nanohorns. Our observations benefit from signal amplification in surface-enhanced Raman scattering (SERS) at sites near a silver surface. We observe nanohorn tip vibration modes in the range 200-500 cm{sup -1}, which are obscured in regular Raman spectra. Ab initio density functional calculations assign modes in this frequency range to local vibrations at the nanohorn cap resembling the radial breathing mode of fullerenes. Careful interpretation of our SERS spectra indicates presence of caps with 5 or 6 pentagons, which are chemically the most active sites. Changes in the peak intensities and frequencies with time indicate that exposure to laser irradiation may cause structural rearrangements at the cap.

  8. Vibrational resonances in biological systems at microwave frequencies.

    Science.gov (United States)

    Adair, Robert K

    2002-03-01

    Many biological systems can be expected to exhibit resonance behavior involving the mechanical vibration of system elements. The natural frequencies of such resonances will, generally, be in the microwave frequency range. Some of these systems will be coupled to the electromagnetic field by the charge distributions they carry, thus admitting the possibility that microwave exposures may generate physiological effects in man and other species. However, such microwave excitable resonances are expected to be strongly damped by interaction with their aqueous biological environment. Although those dissipation mechanisms have been studied, the limitations on energy transfers that follow from the limited coupling of these resonances to the electromagnetic field have not generally been considered. We show that this coupling must generally be very small and thus the absorbed energy is so strongly limited that such resonances cannot affect biology significantly even if the systems are much less strongly damped than expected from basic dissipation models.

  9. Quantitative spectral and orientational analysis in surface sum frequency generation vibrational spectroscopy (SFG-VS)

    Science.gov (United States)

    Wang, Hong-Fei; Gan, Wei; Lu, Rong; Rao, Yi; Wu, Bao-Hua

    Sum frequency generation vibrational spectroscopy (SFG-VS) has been proven to be a uniquely effective spectroscopic technique in the investigation of molecular structure and conformations, as well as the dynamics of molecular interfaces. However, the ability to apply SFG-VS to complex molecular interfaces has been limited by the ability to abstract quantitative information from SFG-VS experiments. In this review, we try to make assessments of the limitations, issues and techniques as well as methodologies in quantitative orientational and spectral analysis with SFG-VS. Based on these assessments, we also try to summarize recent developments in methodologies on quantitative orientational and spectral analysis in SFG-VS, and their applications to detailed analysis of SFG-VS data of various vapour/neat liquid interfaces. A rigorous formulation of the polarization null angle (PNA) method is given for accurate determination of the orientational parameter D = /, and comparison between the PNA method with the commonly used polarization intensity ratio (PIR) method is discussed. The polarization and incident angle dependencies of the SFG-VS intensity are also reviewed, in the light of how experimental arrangements can be optimized to effectively abstract crucial information from the SFG-VS experiments. The values and models of the local field factors in the molecular layers are discussed. In order to examine the validity and limitations of the bond polarizability derivative model, the general expressions for molecular hyperpolarizability tensors and their expression with the bond polarizability derivative model for C3v, C2v and C∞v molecular groups are given in the two appendixes. We show that the bond polarizability derivative model can quantitatively describe many aspects of the intensities observed in the SFG-VS spectrum of the vapour/neat liquid interfaces in different polarizations. Using the polarization analysis in SFG-VS, polarization selection rules or

  10. Generation of intensity duration frequency curves and intensity temporal variability pattern of intense rainfall for Lages/SC

    Directory of Open Access Journals (Sweden)

    Célio Orli Cardoso

    2014-04-01

    Full Text Available The objective of this work was to analyze the frequency distribution and intensity temporal variability of intense rainfall for Lages/SC from diary pluviograph data. Data on annual series of maximum rainfalls from rain gauges of the CAV-UDESC Weather Station in Lages/SC were used from 2000 to 2009. Gumbel statistic distribution was applied in order to obtain the rainfall height and intensity in the following return periods: 2, 5, 10, 15 and 20 years. Results showed intensity-duration-frequency curves (I-D-F for those return periods, as well as I-D-F equations: i=2050.Tr0,20.(t+30-0,89, where i was the intensity, Tr was the rainfall return periods and t was the rainfall duration. For the intensity of temporal variability pattern along of the rainfall duration time, the convective, or advanced pattern was the predominant, with larger precipitate rainfalls in the first half of the duration. The same pattern presented larger occurrences in the spring and summer stations.

  11. Structure and vibrational frequencies of gaseous europium dibromide

    International Nuclear Information System (INIS)

    Giricheva, N.I.; Girichev, S.A.; Shlykov, S.A.; Pelipets, O.V.

    2000-01-01

    Structure of EuBr 2 molecule is studied in the framework of synchronous electron diffraction and mass-spectrometric experiment at the temperature of 1373(20) K. It is found that the molecule has a nonlinear equilibrium configuration, being characterized by the following effective parameters: r g (Eu - Br) = 2.767 A, r g (Br - Br) = 5.11(5) A, l g (Eu - Br) = 0.109(2) A, l g (Br - Br) = 0.388(5) A, valence angle (Br - Eu - Br) = 135.0(3.5) deg. The electron diffraction data permit ascertaining vibration frequencies ν 1 225(10) cm -1 and ν 2 = 40(4) cm -1 [ru

  12. Low-frequency vibration treatment of bone marrow stromal cells induces bone repair in vivo.

    Science.gov (United States)

    He, Shengwei; Zhao, Wenzhi; Zhang, Lu; Mi, Lidong; Du, Guangyu; Sun, Chuanxiu; Sun, Xuegang

    2017-01-01

    To study the effect of low-frequency vibration on bone marrow stromal cell differentiation and potential bone repair in vivo . Forty New Zealand rabbits were randomly divided into five groups with eight rabbits in each group. For each group, bone defects were generated in the left humerus of four rabbits, and in the right humerus of the other four rabbits. To test differentiation, bones were isolated and demineralized, supplemented with bone marrow stromal cells, and implanted into humerus bone defects. Varying frequencies of vibration (0, 12.5, 25, 50, and 100 Hz) were applied to each group for 30 min each day for four weeks. When the bone defects integrated, they were then removed for histological examination. mRNA transcript levels of runt-related transcription factor 2, osteoprotegerin, receptor activator of nuclear factor κ-B ligan, and pre-collagen type 1 α were measured. Humeri implanted with bone marrow stromal cells displayed elevated callus levels and wider, more prevalent, and denser trabeculae following treatment at 25 and 50 Hz. The mRNA levels of runt-related transcription factor 2, osteoprotegerin, receptor activator of nuclear factor κ-B ligand, and pre-collagen type 1 α were also markedly higher following 25 and 50 Hz treatment. Low frequency (25-50 Hz) vibration in vivo can promote bone marrow stromal cell differentiation and repair bone injury.

  13. Analysis of methods for calculating the transition frequencies of the torsional vibration of acrolein isomers in the ground ( S 0) electronic state

    Science.gov (United States)

    Koroleva, L. A.; Tyulin, V. I.; Matveev, V. K.; Pentin, Yu. A.

    2013-05-01

    B3LYP, MP2, CCSD(T), and MP4/MP2 in the 6-311G( d, p), 6-311++G( d, p), cc-pVTZ, aug-cc-pVTZ bases used to calculate the transition frequencies of torsional vibration of trans- and cis-isomers of acrolein in the ground electronic state ( S 0) are analyzed. It is found that for trans-isomers, all methods of calculation except for B3LYP in the cc-pVTZ basis yield good agreement between the calculated and experimental values. It is noted that for the cis-isomer of acrolein, no method of calculation confirms the experimental value of the frequency of torsional vibration (138 cm-1). It is shown that the calculated and experimental values for obertones at 273.0 cm-1 and other transitions of torsional vibration are different for this isomer in particular. However, it is established that in some calculation methods (B3LYP, MP2), the frequency of the torsional vibration of the cis-isomer coincides with another experimental value of this frequency (166.5 cm-1). It is concluded that in analyzing the vibrational structure of the UV spectrum, the calculated and experimental values of its obertone (331.3 cm-1) coincide, along with its frequency. It is also noted that the frequency of torsional vibration for the cis-isomer (166.5 cm-1) can also be found in other experimental works if we change the allocation of torsional transition 18{1/1}.

  14. Vibrational frequency analysis, FT-IR, DFT and M06-2X studies on tert-Butyl N-(thiophen-2yl)carbamate

    Science.gov (United States)

    Sert, Yusuf; Singer, L. M.; Findlater, M.; Doğan, Hatice; Çırak, Ç.

    2014-07-01

    In this study, the experimental and theoretical vibrational frequencies of a newly synthesized tert-Butyl N-(thiophen-2yl)carbamate have been investigated. The experimental FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase have been recorded. The theoretical vibrational frequencies and optimized geometric parameters (bond lengths and bond angles) have been calculated by using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and DFT/M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with the 6-311++G(d,p) basis set by Gaussian 09W software, for the first time. The vibrational frequencies have been assigned using potential energy distribution (PED) analysis by using VEDA 4 software. The computational optimized geometric parameters and vibrational frequencies have been found to be in good agreement with the corresponding experimental data, and with related literature results. In addition, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energies and the other related molecular energy values have been calculated and are depicted.

  15. Ship Vibrations

    DEFF Research Database (Denmark)

    Sørensen, Herman

    1997-01-01

    Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board......Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board...

  16. A study on the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise

    Directory of Open Access Journals (Sweden)

    Yukio Takahashi

    2011-01-01

    Full Text Available To investigate the contribution of body vibrations to the vibratory sensation induced by high-level, complex low-frequency noise, we conducted two experiments. In Experiment 1, eight male subjects were exposed to seven types of low-frequency noise stimuli: two pure tones [a 31.5-Hz, 100-dB(SPL tone and a 50-Hz, 100-dB(SPL tone] and five complex noises composed of the pure tones. For the complex noise stimuli, the sound pressure level of one tonal component was 100 dB(SPL and that of another one was either 90, 95, or 100 dB(SPL. Vibration induced on the body surface was measured at five locations, and the correlation with the subjective rating of the vibratory sensation at each site of measurement was examined. In Experiment 2, the correlation between the body surface vibration and the vibratory sensation was similarly examined using seven types of noise stimuli composed of a 25-Hz tone and a 50-Hz tone. In both the experiments, we found that at the chest and the abdomen, the rating of the vibratory sensation was in close correlation with the vibration acceleration level (VAL of the body surface vibration measured at each corresponding location. This was consistent with our previous results and suggested that at the trunk of the body (the chest and the abdomen, the mechanoreception of body vibrations plays an important role in the experience of the vibratory sensation in persons exposed to high-level low-frequency noise. At the head, however, no close correlation was found between the rating of the vibratory sensation and the VAL of body surface vibration. This suggested that at the head, the perceptual mechanisms of vibration induced by high-level low-frequency noise were different from those in the trunk of the body.

  17. Research on the Vibration Insulation of High-Speed Train Bogies in Mid and High Frequency

    Directory of Open Access Journals (Sweden)

    Jia Liu

    2018-01-01

    Full Text Available According to a large amount of the test data, the mid and high frequency vibrations of high-speed bogies are very notable, especially in the 565~616 Hz range, which are just the passing frequencies corresponding to the 22nd to 24th polygonal wear of the wheel. In order to investigate the main cause of wheel higher-order polygon formation, a 3D flexible model of a Chinese high-speed train bogie is developed using the explicit finite element method. The results show that the couple vibration of bogie and wheelset may lead to the high-order wears of wheel. In order to reduce the coupled resonance of the wheelset and the bogie frame, the effects of the stiffness and damping of the primary suspensions, wheelset axle radius, and bogie frame strength on the vibration transmissibility are discussed carefully. The numerical results show that the resonance peaks in high frequency range can be reduced by reducing the stiffness of axle box rotary arm joint, reducing the wheelset axle radius or strengthening the bogie frame location. The related results may provide a reference for structure improvement of the existing bogies and structure design of the new high-speed bogies.

  18. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    International Nuclear Information System (INIS)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-01-01

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed

  19. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Maekawa, Hiroaki; Sul, Soohwan [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States); Ge, Nien-Hui, E-mail: nhge@uci.edu [Department of Chemistry, University of California at Irvine, Irvine, CA 92697-2025 (United States)

    2013-08-30

    Highlights: ► Vibrational dynamics of conjugated C=O and N=N modes of ethyl diazoacetate was studied. ► Their frequency–frequency correlation functions are different. ► The dual-frequency 2D IR spectrum indicates anticorrelated frequency fluctuations. ► Correlation effects on dual-frequency 2D IR spectra are discussed. ► The existence of cis and trans conformers is revealed in 2D IR spectra. - Abstract: We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester C=O and diazo N=N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency–frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single C=O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  20. Balancing Vibrations at Harmonic Frequencies by Injecting Harmonic Balancing Signals into the Armature of a Linear Motor/Alternator Coupled to a Stirling Machine

    Science.gov (United States)

    Holliday, Ezekiel S. (Inventor)

    2014-01-01

    Vibrations at harmonic frequencies are reduced by injecting harmonic balancing signals into the armature of a linear motor/alternator coupled to a Stirling machine. The vibrations are sensed to provide a signal representing the mechanical vibrations. A harmonic balancing signal is generated for selected harmonics of the operating frequency by processing the sensed vibration signal with adaptive filter algorithms of adaptive filters for each harmonic. Reference inputs for each harmonic are applied to the adaptive filter algorithms at the frequency of the selected harmonic. The harmonic balancing signals for all of the harmonics are summed with a principal control signal. The harmonic balancing signals modify the principal electrical drive voltage and drive the motor/alternator with a drive voltage component in opposition to the vibration at each harmonic.

  1. Understanding the influence of low-frequency vibrations on the hydrogen bonds of acetic acid and acetamide dimers.

    Science.gov (United States)

    Copeland, Christopher; Menon, Omkaran; Majumdar, D; Roszak, Szczepan; Leszczynski, Jerzy

    2017-09-20

    Low-frequency vibrations coupled to high-frequency modes are known to influence the hydrogen bond strengths in a weakly interacting dimer. In this context, various acetic acid and acetamide dimers were analyzed using Møller-Plesset second-order perturbation (MP2) and density functional theory (DFT)-based approaches with explicit anharmonicity corrections. The computed low-frequency fundamentals as well as the high-frequency modes, which were found to be related to hydrogen bonding (OH/NH stretching modes), were analyzed and their computed intensities were correlated with their hydrogen-bond strengths/binding energies. There are similarities in the nature of eight low-frequency fundamentals of these two dimers, and the in-plane bending and stretch-bend fundamentals of the different dimers of these two species (in this low-frequency region) have specific roles in their relative stability order. The computed linear correlations were further verified against the results from coupled cluster calculations including triple excitation (CCSD(T)), Gaussian-G4 (G4), Gaussian-G2-MP2 (G2MP2) and complete basis set (CBS-QB3) methods of high accuracy energy calculations. As a consequence of such linear correlations, an additive property of local fragment energies (responsible for hydrogen bonding) was found to be a valid approximation to predict the binding energies of such dimers and the idea was found to be extendable to the other homologues of these acids/amides.

  2. Frequency Response of the Sample Vibration Mode in Scanning Probe Acoustic Microscope

    International Nuclear Information System (INIS)

    Ya-Jun, Zhao; Qian, Cheng; Meng-Lu, Qian

    2010-01-01

    Based on the interaction mechanism between tip and sample in the contact mode of a scanning probe acoustic microscope (SPAM), an active mass of the sample is introduced in the mass-spring model. The tip motion and frequency response of the sample vibration mode in the SPAM are calculated by the Lagrange equation with dissipation function. For the silicon tip and glass assemblage in the SPAM the frequency response is simulated and it is in agreement with the experimental result. The living myoblast cells on the glass slide are imaged at resonance frequencies of the SPAM system, which are 20kHz, 30kHz and 120kHz. It is shown that good contrast of SPAM images could be obtained when the system is operated at the resonance frequencies of the system in high and low-frequency regions

  3. Investigation of a vibration-damping unit for reduction in low-frequency vibrations of electric motors

    Science.gov (United States)

    Grigoryey, N. V.; Fedorovich, M. A.

    1973-01-01

    The vibroacoustical characteristics of different types of electric motors are discussed. It is shown that the basic source of low frequency vibrations is rotor unbalance. A flexible damping support, with an antivibrator, is used to obtain the vibroacoustical effect of reduction in the basic harmonic of the electric motor. A model of the electric motor and the damping apparatus is presented. Mathematical models are developed to show the relationships of the parameters. The basic purpose in using a calculation model id the simultaneous replacement of the exciting force created by the rotor unbalance and its inertial rigidity characteristics by a limiting kinematic disturbance.

  4. The effect of an external electric field on the vibrational frequency of CO

    Science.gov (United States)

    Bauschlicher, C. W., Jr.

    1985-01-01

    Ab initio calculations, using a CAS SCF wavefunction and extended basis set, show a change in the vibrational frequency with electric field strength for the ground 1sigma(+) state of CO of one third that observed for CO/Ni(110). This result supports the view of Lambert.

  5. Effect of intermolecular hydrogen bonding, vibrational analysis and molecular structure of a biomolecule: 5-Hydroxymethyluracil

    Science.gov (United States)

    Çırak, Çağrı; Sert, Yusuf; Ucun, Fatih

    2014-06-01

    In the present work, the experimental and theoretical vibrational spectra of 5-hydroxymethyluracil were investigated. The FT-IR (4000-400 cm-1) spectrum of the molecule in the solid phase was recorded. The geometric parameters (bond lengths and bond angles), vibrational frequencies, Infrared intensities of the title molecule in the ground state were calculated using density functional B3LYP and M06-2X methods with the 6-311++G(d,p) basis set for the first time. The optimized geometric parameters and theoretical vibrational frequencies were found to be in good agreement with the corresponding experimental data, and with the results found in the literature. The vibrational frequencies were assigned based on the potential energy distribution using the VEDA 4 program. The dimeric form of 5-hydroxymethyluracil molecule was also simulated to evaluate the effect of intermolecular hydrogen bonding on its vibrational frequencies. It was observed that the Nsbnd H stretching modes shifted to lower frequencies, while its in-plane and out-of-plane bending modes shifted to higher frequencies due to the intermolecular Nsbnd H⋯O hydrogen bond. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies and diagrams were presented.

  6. Low Frequency Vibration approach to asess the Performance of wood structural Systems

    Science.gov (United States)

    Xiping Wang; Robert J. Ross; Michael O. Hunt

    2004-01-01

    The primary means of inspecting buildings and other structures is to evaluate each structure member individually. This is a time consuming process that is expensive, particularly if sheathing or other covering materials must be removed to access the structural members. This paper presents an effort to use a low frequency vibration method for assessing the structural...

  7. Low-frequency vibration treatment of bone marrow stromal cells induces bone repair in vivo

    Directory of Open Access Journals (Sweden)

    Shengwei He

    2017-01-01

    Full Text Available Objective(s:To study the effect of low-frequency vibration on bone marrow stromal cell differentiation and potential bone repair in vivo. Materials and Methods:Forty New Zealand rabbits were randomly divided into five groups with eight rabbits in each group. For each group, bone defects were generated in the left humerus of four rabbits, and in the right humerus of the other four rabbits. To test differentiation, bones were isolated and demineralized, supplemented with bone marrow stromal cells, and implanted into humerus bone defects. Varying frequencies of vibration (0, 12.5, 25, 50, and 100 Hz were applied to each group for 30 min each day for four weeks. When the bone defects integrated, they were then removed for histological examination. mRNA transcript levels of runt-related transcription factor 2, osteoprotegerin, receptor activator of nuclear factor k-B ligan, and pre-collagen type 1 a were measured. Results:Humeri implanted with bone marrow stromal cells displayed elevated callus levels and wider, more prevalent, and denser trabeculae following treatment at 25 and 50 Hz. The mRNA levels of runt-related transcription factor 2, osteoprotegerin, receptor activator of nuclear factor k-B ligand, and pre-collagen type 1 a were also markedly higher following 25 and 50 Hz treatment. Conclusion:Low frequency (25–50 Hz vibration in vivo can promote bone marrow stromal cell differentiation and repair bone injury.

  8. Derivatives of buckling loads and vibration frequencies with respect to stiffness and initial strain parameters

    Science.gov (United States)

    Haftka, Raphael T.; Cohen, Gerald A.; Mroz, Zenon

    1990-01-01

    A uniform variational approach to sensitivity analysis of vibration frequencies and bifurcation loads of nonlinear structures is developed. Two methods of calculating the sensitivities of bifurcation buckling loads and vibration frequencies of nonlinear structures, with respect to stiffness and initial strain parameters, are presented. A direct method requires calculation of derivatives of the prebuckling state with respect to these parameters. An adjoint method bypasses the need for these derivatives by using instead the strain field associated with the second-order postbuckling state. An operator notation is used and the derivation is based on the principle of virtual work. The derivative computations are easily implemented in structural analysis programs. This is demonstrated by examples using a general purpose, finite element program and a shell-of-revolution program.

  9. VIBRATION ISOLATION SYSTEM PROBABILITY ANALYSIS

    Directory of Open Access Journals (Sweden)

    Smirnov Vladimir Alexandrovich

    2012-10-01

    Full Text Available The article deals with the probability analysis for a vibration isolation system of high-precision equipment, which is extremely sensitive to low-frequency oscillations even of submicron amplitude. The external sources of low-frequency vibrations may include the natural city background or internal low-frequency sources inside buildings (pedestrian activity, HVAC. Taking Gauss distribution into account, the author estimates the probability of the relative displacement of the isolated mass being still lower than the vibration criteria. This problem is being solved in the three dimensional space, evolved by the system parameters, including damping and natural frequency. According to this probability distribution, the chance of exceeding the vibration criteria for a vibration isolation system is evaluated. Optimal system parameters - damping and natural frequency - are being developed, thus the possibility of exceeding vibration criteria VC-E and VC-D is assumed to be less than 0.04.

  10. Refinements in the vibration frequencies of H3+ and D3+

    International Nuclear Information System (INIS)

    Carney, G.D.

    1980-01-01

    Refinements in vibration intervals of the order of 1 per cent are reported for H 3 + and D 3 + . These improved intervals result from the addition of polarization terms to the electronic wavefunction previously obtained with a complete configuration-interaction treatment of electron correlation using a 21 floating gaussian lobe basis. Twelve additional floating gaussian lobe orbitals were used to construct 78 additional configuration-interaction functions. Positions and exponents of these additional floating gaussian lobe orbitals were carefully chosen to allow for polarization of the correlated wavefunctions. Calculated vibrational state-averaged and observed geometries for H 3 + agree to within 0.01 A; refined fundamental frequencies are νsub(A) = 3220.48 and νsub(E) = 2545.99 cm -1 for H 3 + , and νsub(A) = 2332.94 and νsub(E) = 1848.12 cm -1 for D 3 + . Einstein coefficients for spontaneous emission of radiation from infrared active states of H 3 + and D 3 + are reported, and an alternative to the Carney-Porter method of vibration analysis is used to confirm the accuracy of their method for axial molecules such as H 3 + . (author)

  11. Vibrational Spectroscopy and Astrobiology

    Science.gov (United States)

    Chaban, Galina M.; Kwak, D. (Technical Monitor)

    2001-01-01

    Role of vibrational spectroscopy in solving problems related to astrobiology will be discussed. Vibrational (infrared) spectroscopy is a very sensitive tool for identifying molecules. Theoretical approach used in this work is based on direct computation of anharmonic vibrational frequencies and intensities from electronic structure codes. One of the applications of this computational technique is possible identification of biological building blocks (amino acids, small peptides, DNA bases) in the interstellar medium (ISM). Identifying small biological molecules in the ISM is very important from the point of view of origin of life. Hybrid (quantum mechanics/molecular mechanics) theoretical techniques will be discussed that may allow to obtain accurate vibrational spectra of biomolecular building blocks and to create a database of spectroscopic signatures that can assist observations of these molecules in space. Another application of the direct computational spectroscopy technique is to help to design and analyze experimental observations of ice surfaces of one of the Jupiter's moons, Europa, that possibly contains hydrated salts. The presence of hydrated salts on the surface can be an indication of a subsurface ocean and the possible existence of life forms inhabiting such an ocean.

  12. Research on a new type of precision cropping method with variable frequency vibration

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Aiming at the cropping operations widely applied in practical industry production, a new method of bar cropping is presented. The rotational speeds of actuating motor of eccentric blocks are controlled by a frequency-changer, and the shearing die provides the bar with the controllable force, frequency and amplitude of vibration. By utilizing the stress concentration at the bottom of V shape groove on the bar, the low stress bar cropping is realized. The bar cropping experiments of duralumin alloy and steel ...

  13. Natural Frequencies Evaluation on Partially Damaged Building using Ambient Vibration Technique

    Science.gov (United States)

    Kamarudin, A. F.; Zainal Abidin, M. H.; Daud, M. E.; Noh, M. S. Md; Madun, A.; Ibrahim, A.; Matarul, J.; Mokhatar, S. N.

    2018-04-01

    Severe damages observed on the school blocks, roads, retaining walls and drainage within the compound of SMK Kundasang Sabah possibly due to the ground movements triggered by the Ranau earthquake in 1991. Ambient vibration measurements were carried on the remaining demolished 3-storey building which partially damaged in order to measure the predominant building frequencies using tri-axial 1 Hz seismometer sensors. Popular methods of Horizontal-to-vertical spectral ratios (HVSR) and Fourier amplitude spectra (FAS) were used to compute the ambient vibration wave fields of each building axes (Transverse or North-South (NS), Longitudinal or East-West (EW) and vertical) into Fourier spectra. Two main modes of translation and torsion were observed from the peaks frequencies obtained at 2.99 to 3.10 Hz (1st mode), 4.85 Hz (2nd mode) and 5.63 to 5.85 Hz (3rd mode). The building experiencing translation modes of bending and shear in the NS and EW directions. It could be seen when the amplitudes tends to increase when the floor are increased. Meanwhile, the torsional bending mode is expected to occur when the deformation amplitudes are found to be increasing horizontally, when moving into partially structural damaged section located on the East wing of building.

  14. CONDITIONS FOR STABLE CHIP BREAKING AND PROVISION OF MACHINED SURFACE QUALITY WHILE TURNING WITH ASYMMETRIC TOOL VIBRATIONS

    Directory of Open Access Journals (Sweden)

    V. K. Sheleh

    2015-01-01

    Full Text Available The paper considers a process of turning structural steel with asymmetric tool vibrations directed along feeding. Asymmetric vibrations characterized by asymmetry coefficient of vibration cycle, their frequency and amplitude are additionally transferred to the tool in the turning process with the purpose to crush chips. Conditions of stable chip breaking and obtaining optimum dimensions of chip elements have been determined in the paper. In order to reduce a negative impact of the vibration amplitude on a cutting process and quality of the machined surfaces machining must be carried out with its minimum value. In this case certain ratio of the tool vibration frequency to the work-piece rotation speed has been ensured in the paper. A formula has been obtained for calculation of this ratio with due account of the expected length of chip elements and coefficient of vibration cycle asymmetry.Influence of the asymmetric coefficient of the tool vibration cycle on roughness of the machined surfaces and cutting tool wear has been determined in the paper. According to the results pertaining to machining of work-pieces made of 45 and ШХ15 steel the paper presents mathematical relationships of machined surface roughness with cutting modes and asymmetry coefficient of tool vibration cycle. Tool feeding being one of the cutting modes exerts the most significant impact on the roughness value and increase of the tool feeding entails increase in roughness. Reduction in coefficient of vibration cycle asymmetry contributes to surface roughness reduction. However, the cutting tool wear occurs more intensive. Coefficient of the vibration cycle asymmetry must be increased in order to reduce wear rate. Therefore, the choice of the coefficient of the vibration cycle asymmetry is based on the parameters of surface roughness which must be obtained after machining and intensity of tool wear rate.The paper considers a process of turning structural steel with asymmetric

  15. Low-frequency, low-magnitude vibrations (LFLM enhances chondrogenic differentiation potential of human adipose derived mesenchymal stromal stem cells (hASCs

    Directory of Open Access Journals (Sweden)

    Krzysztof Marycz

    2016-02-01

    Full Text Available The aim of this study was to evaluate if low-frequency, low-magnitude vibrations (LFLM could enhance chondrogenic differentiation potential of human adipose derived mesenchymal stem cells (hASCs with simultaneous inhibition of their adipogenic properties for biomedical purposes. We developed a prototype device that induces low-magnitude (0.3 g low-frequency vibrations with the following frequencies: 25, 35 and 45 Hz. Afterwards, we used human adipose derived mesenchymal stem cell (hASCS, to investigate their cellular response to the mechanical signals. We have also evaluated hASCs morphological and proliferative activity changes in response to each frequency. Induction of chondrogenesis in hASCs, under the influence of a 35 Hz signal leads to most effective and stable cartilaginous tissue formation through highest secretion of Bone Morphogenetic Protein 2 (BMP-2, and Collagen type II, with low concentration of Collagen type I. These results correlated well with appropriate gene expression level. Simultaneously, we observed significant up-regulation of α3, α4, β1 and β3 integrins in chondroblast progenitor cells treated with 35 Hz vibrations, as well as Sox-9. Interestingly, we noticed that application of 35 Hz frequencies significantly inhibited adipogenesis of hASCs. The obtained results suggest that application of LFLM vibrations together with stem cell therapy might be a promising tool in cartilage regeneration.

  16. Vibrational correlation between conjugated carbonyl and diazo modes studied by single- and dual-frequency two-dimensional infrared spectroscopy

    Science.gov (United States)

    Maekawa, Hiroaki; Sul, Soohwan; Ge, Nien-Hui

    2013-08-01

    We have applied infrared three-pulse photon echo and single- and dual-frequency 2D IR spectroscopy to the ester Cdbnd O and diazo Ndbnd N stretching modes in ethyl diazoacetate (EDA), and investigated their vibrational frequency fluctuations and correlation. The two modes exhibit different vibrational dynamics and 2D lineshape, which are well simulated by frequency-frequency correlation functions (FFCFs) with two decaying components. Although the FT IR spectrum shows a single Cdbnd O band, absolute magnitude 2D IR nonrephasing spectrum displays spectral signatures supporting the presence of cis and trans conformations. The cross-peak inclined toward the anti-diagonal in the dual-frequency 2D IR spectrum, indicating that the frequency fluctuations of the two modes are anticorrelated. This behavior is attributed to anticorrelated change in the bond orders when solvent and structural fluctuations causes EDA to adopt a different mixture of the two dominant resonance structures. The effects of cross FFCF on the cross-peak line shape are discussed.

  17. Electronic energy transfer through non-adiabatic vibrational-electronic resonance. II. 1D spectra for a dimer

    Science.gov (United States)

    Tiwari, Vivek; Jonas, David M.

    2018-02-01

    Vibrational-electronic resonance in photosynthetic pigment-protein complexes invalidates Förster's adiabatic framework for interpreting spectra and energy transfer, thus complicating determination of how the surrounding protein affects pigment properties. This paper considers the combined effects of vibrational-electronic resonance and inhomogeneous variations in the electronic excitation energies of pigments at different sites on absorption, emission, circular dichroism, and hole-burning spectra for a non-degenerate homodimer. The non-degenerate homodimer has identical pigments in different sites that generate differences in electronic energies, with parameters loosely based on bacteriochlorophyll a pigments in the Fenna-Matthews-Olson antenna protein. To explain the intensity borrowing, the excited state vibrational-electronic eigenvectors are discussed in terms of the vibrational basis localized on the individual pigments, as well as the correlated/anti-correlated vibrational basis delocalized over both pigments. Compared to those in the isolated pigment, vibrational satellites for the correlated vibration have the same frequency and precisely a factor of 2 intensity reduction through vibrational delocalization in both absorption and emission. Vibrational satellites for anti-correlated vibrations have their relaxed emission intensity reduced by over a factor 2 through vibrational and excitonic delocalization. In absorption, anti-correlated vibrational satellites borrow excitonic intensity but can be broadened away by the combination of vibronic resonance and site inhomogeneity; in parallel, their vibronically resonant excitonic partners are also broadened away. These considerations are consistent with photosynthetic antenna hole-burning spectra, where sharp vibrational and excitonic satellites are absent. Vibrational-excitonic resonance barely alters the inhomogeneously broadened linear absorption, emission, and circular dichroism spectra from those for a

  18. Fabrication and characterization of non-resonant magneto-mechanical low-frequency vibration energy harvester

    Science.gov (United States)

    Nammari, Abdullah; Caskey, Logan; Negrete, Johnny; Bardaweel, Hamzeh

    2018-03-01

    This article presents a non-resonant magneto-mechanical vibration energy harvester. When externally excited, the energy harvester converts vibrations into electric charge using a guided levitated magnet oscillating inside a multi-turn coil that is fixed around the exterior of the energy harvester. The levitated magnet is guided using four oblique mechanical springs. A prototype of the energy harvester is fabricated using additive manufacturing. Both experiment and model are used to characterize the static and dynamic behavior of the energy harvester. Measured restoring forces show that the fabricated energy harvester retains a mono-stable potential energy well with desired stiffness nonlinearities. Results show that magnetic spring results in hardening effect which increases the resonant frequency of the energy harvester. Additionally, oblique mechanical springs introduce geometric, negative, nonlinear stiffness which improves the harvester's response towards lower frequency spectrum. The unique design can produce a tunable energy harvester with multi-well potential energy characteristics. A finite element model is developed to estimate the average radial flux density experienced by the multi-turn coil. Also, a lumped parameter model of the energy harvester is developed and validated against measured data. Both upward and downward frequency sweeps are performed to determine the frequency response of the harvester. Results show that at higher excitation levels hardening effects become more apparent, and the system dynamic response turns into non-resonant. Frequency response curves exhibit frequency jump phenomena as a result of coexistence of multiple energy states at the frequency branch. The fabricated energy harvester is hand-held and measures approximately 100.5 [cm3] total volume. For a base excitation of 1.0 g [m/s2], the prototype generates a peak voltage and normalized power density of approximately 3.5 [V] and 0.133 [mW/cm3 g2], respectively, at 15.5 [Hz].

  19. High-frequency, low-intensity vibrations increase bone mass and muscle strength in upper limbs, improving autonomy in disabled children.

    Science.gov (United States)

    Reyes, M Loreto; Hernández, Marta; Holmgren, Luz J; Sanhueza, Enrique; Escobar, Raúl G

    2011-08-01

    Disuse osteoporosis in children is a progressive disease that can affect quality of life. High-frequency, low-magnitude vibration (HFLMV) acts as an anabolic signal for bone and muscle. We undertook a prospective, randomized, double-blind, placebo-controlled clinical trial to assess the efficacy and safety of regional HFLMV in disabled children. Sixty-five children 6 to 9 year of age were randomized into three groups: placebo, 60 Hz, and 90 Hz. In the two active groups, a 0.3-g mechanical vibration was delivered to the radii and femurs for 5 minutes each day. After 6 months, the main endpoint was bone mineral density (BMD) at the ultradistal radius (UDR), 33% radii (33%R), and femoral necks (FN). Secondary endpoints were area and bone mineral content (BMC) at the UDR, 33%R, and FN; grip force of the upper and lower limbs; motor function; and PedsQL evaluation. An intention-to-treat analysis was used. Fifty-seven children (88%) completed the protocol. A significant increase was observed in the 60-Hz group relative to the other groups in BMD at the UDR (p = .011), in grip force of the upper limbs (p = .035), and in the "daily activities item" (p = .035). A mixed model to evaluate the response to intervention showed a stronger effect of 60 Hz on patients with cerebral palsy on the UDR and that between-subject variability significantly affected the response. There were no reported side effects of the intervention. This work provides evidence that regional HFLMV is an effective and safe strategy to improve bone mass, muscle strength, and possibly independence in children with motor disabilities. Copyright © 2011 American Society for Bone and Mineral Research.

  20. O modelo AM1 na previsão de frequências vibracionais The vibration frequencies predicted by the AM1 model

    Directory of Open Access Journals (Sweden)

    João Carlos Silva Ramos

    1999-09-01

    Full Text Available We analyse vibrational frequencies of 168 compounds with the AM1 model concerning its experimentally observed gaseous frequencies. Stretching of CH, NH, OH and CO bonds, its related bending frequencies, and the CC frame movements are the studied vibrations. The results show problems with the AM1 vibrational splittings. Often symmetric stretching frequencies, like in CH3, CH2 and NH3, appear switched with the corresponding antisymmetrical ones. Among the studied vibrations many stretchings are overestimated, while bendings oscillate around experimental values. Fluorine stretchings, NN, OO, CH, double and triples CC bonds and cyclic hydrocarbon breathing modes are always overestimated while torsions, umbrella modes and OH/SH stretching are, in average, underestimated. Graphical analysis show that compounds with the lowest molecular masses are the ones with the largest difference to the experimental values. From our results it is not possible to fit confortably the calculated frequencies by a simple linear relationship of the type, n(obs=a*n(AM1. Better aggreement is obtained when different curves are adjusted for the stretching and bending modes, and when a complete linear function is used. Among our studies the best obtained statistical results are for CH, NH and OH. The conclusions obtained in this work will improve the AM1 calculated frequencies leading to accurate results for these properties.

  1. 2D heterodyne-detected sum frequency generation study on the ultrafast vibrational dynamics of H{sub 2}O and HOD water at charged interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Inoue, Ken-ichi; Singh, Prashant C. [Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Nihonyanagi, Satoshi; Tahara, Tahei, E-mail: tahei@riken.jp [Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Ultrafast Spectroscopy Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yamaguchi, Shoichi [Molecular Spectroscopy Laboratory, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Department of Applied Chemistry, Saitama University, 255 Shimo-Okubo, Saitama 338-8570 (Japan)

    2015-06-07

    Two-dimensional heterodyne-detected vibrational sum-frequency generation (2D HD-VSFG) spectroscopy is applied to study the ultrafast vibrational dynamics of water at positively charged aqueous interfaces, and 2D HD-VSFG spectra of cetyltrimethylammonium bromide (CTAB)/water interfaces in the whole hydrogen-bonded OH stretch region (3000 cm{sup −1} ≤ ω{sub pump} ≤ 3600 cm{sup −1}) are measured. 2D HD-VSFG spectrum of the CTAB/isotopically diluted water (HOD-D{sub 2}O) interface exhibits a diagonally elongated bleaching lobe immediately after excitation, which becomes round with a time constant of ∼0.3 ps due to spectral diffusion. In contrast, 2D HD-VSFG spectrum of the CTAB/H{sub 2}O interface at 0.0 ps clearly shows two diagonal peaks and their cross peaks in the bleaching region, corresponding to the double peaks observed at 3230 cm{sup −1} and 3420 cm{sup −1} in the steady-state HD-VSFG spectrum. Horizontal slices of the 2D spectrum show that the relative intensity of the two peaks of the bleaching at the CTAB/H{sub 2}O interface gradually change with the change of the pump frequency. We simulate the pump-frequency dependence of the bleaching feature using a model that takes account of the Fermi resonance and inhomogeneity of the OH stretch vibration, and the simulated spectra reproduce the essential features of the 2D HD-VSFG spectra of the CTAB/H{sub 2}O interface. The present study demonstrates that heterodyne detection of the time-resolved VSFG is critically important for studying the ultrafast dynamics of water interfaces and for unveiling the underlying mechanism.

  2. Frequency tuning and directional sensitivity of tympanal vibrations in the field cricket Gryllus bimaculatus

    DEFF Research Database (Denmark)

    Lankheet, Martin J.; Cerkvenik, Uroš; Larsen, Ole Næsbye

    2017-01-01

    Female field crickets use phonotaxis to locate males by their calling song. Male song production and female behavioural sensitivity form a pair of matched frequency filters, which in Gryllus bimaculatus are tuned to a frequency of about 4.7 kHz. Directional sensitivity is supported by an elaborate...... play a major role in tuning directional sensitivity to the calling song frequency, by measuring tympanal vibrations as a function of sound direction and frequency. Rather than sharp frequency tuning of directional sensitivity corresponding to the calling song, we found broad frequency tuning......, with optima shifted to higher frequencies. These findings agree with predictions from a vector summation model for combining external and internal sounds. We show that the model provides robust directional sensitivity that is, however, broadly tuned with an optimum well above the calling song frequency. We...

  3. Quantification of crystalline cellulose in lignocellulosic biomass using sum frequency generation (SFG) vibration spectroscopy and comparison with other analytical methods.

    Science.gov (United States)

    Barnette, Anna L; Lee, Christopher; Bradley, Laura C; Schreiner, Edward P; Park, Yong Bum; Shin, Heenae; Cosgrove, Daniel J; Park, Sunkyu; Kim, Seong H

    2012-07-01

    The non-centrosymmetry requirement of sum frequency generation (SFG) vibration spectroscopy allows the detection and quantification of crystalline cellulose in lignocellulose biomass without spectral interferences from hemicelluloses and lignin. This paper shows a correlation between the amount of crystalline cellulose in biomass and the SFG signal intensity. Model biomass samples were prepared by mixing commercially available cellulose, xylan, and lignin to defined concentrations. The SFG signal intensity was found sensitive to a wide range of crystallinity, but varied non-linearly with the mass fraction of cellulose in the samples. This might be due to the matrix effects such as light scattering and absorption by xylan and lignin, as well as the non-linear density dependence of the SFG process itself. Comparison with other techniques such as XRD, FT-Raman, FT-IR and NMR demonstrate that SFG can be a complementary and sensitive tool to assess crystalline cellulose in biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.

  4. Psychophysical estimate of plantar vibration sensitivity brings additional information to the detection threshold in young and elderly subjects

    Directory of Open Access Journals (Sweden)

    Yves Jammes

    Full Text Available Objective: Vibration detection threshold of the foot sole was compared to the psychophysical estimate of vibration in a wide range of amplitudes in young (20–34 years old and elderly subjects (53–67 years old. Methods: The vibration detection threshold was determined on the hallux, 5th metatarsal head, and heel at frequencies of 25, 50 and 150 Hz. For vibrations of higher amplitude (reaching 360 μm, the Stevens power function (Ψ = k * Φn allowed to obtain regression equations between the vibration estimate (Ψ and its physical magnitude (Φ, the n coefficient giving the subjective intensity in vibration perception. We searched for age-related changes in the vibration perception by the foot sole. Results: In all participants, higher n values were measured at vibration frequencies of 150 Hz and, compared to the young adults the elderly had lower n values measured at this frequency. Only in the young participants, the vibration detection threshold was lowered at 150 Hz. Conclusion: The psychophysical estimate brings further information than the vibration detection threshold which is less affected by age. Significance: The clinical interest of psychophysical vibration estimate was assessed in a patient with a unilateral alteration of foot sensitivity. Keywords: Vibration sensitivity, Vibration detection threshold, Foot sole, Elderly

  5. Ocular vestibular evoked myogenic potentials to vertex low frequency vibration as a diagnostic test for superior canal dehiscence.

    Science.gov (United States)

    Verrecchia, Luca; Westin, Magnus; Duan, Maoli; Brantberg, Krister

    2016-04-01

    To explore ocular vestibular evoked myogenic potentials (oVEMP) to low-frequency vertex vibration (125 Hz) as a diagnostic test for superior canal dehiscence (SCD) syndrome. The oVEMP using 125 Hz single cycle bone-conducted vertex vibration were tested in 15 patients with unilateral superior canal dehiscence (SCD) syndrome, 15 healthy controls and in 20 patients with unilateral vestibular loss due to vestibular neuritis. Amplitude, amplitude asymmetry ratio, latency and interaural latency difference were parameters of interest. The oVEMP amplitude was significantly larger in SCD patients when affected sides (53 μVolts) were compared to non-affected (17.2 μVolts) or compared to healthy controls (13.6 μVolts). Amplitude larger than 33.8 μVolts separates effectively the SCD ears from the healthy ones with sensitivity of 87% and specificity of 93%. The other three parameters showed an overlap between affected SCD ears and non-affected as well as between SCD ears and those in the two control groups. oVEMP amplitude distinguishes SCD ears from healthy ones using low-frequency vibration stimuli at vertex. Amplitude analysis of oVEMP evoked by low-frequency vertex bone vibration stimulation is an additional indicator of SCD syndrome and might serve for diagnosing SCD patients with coexistent conductive middle ear problems. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  6. Towards an autonomous self-tuning vibration energy harvesting device for wireless sensor network applications

    International Nuclear Information System (INIS)

    Challa, Vinod R; Prasad, M G; Fisher, Frank T

    2011-01-01

    Future deployment of wireless sensor networks will ultimately require a self-sustainable local power source for each sensor, and vibration energy harvesting is a promising approach for such applications. A requirement for efficient vibration energy harvesting is to match the device and source frequencies. While techniques to tune the resonance frequency of an energy harvesting device have recently been described, in many applications optimization of such systems will require the energy harvesting device to be able to autonomously tune its resonance frequency. In this work a vibration energy harvesting device with autonomous resonance frequency tunability utilizing a magnetic stiffness technique is presented. Here a piezoelectric cantilever beam array is employed with magnets attached to the free ends of cantilever beams to enable magnetic force resonance frequency tuning. The device is successfully tuned from − 27% to + 22% of its untuned resonance frequency while outputting a peak power of approximately 1 mW. Since the magnetic force tuning technique is semi-active, energy is only consumed during the tuning process. The developed prototype consumed maximum energies of 3.3 and 3.9 J to tune to the farthest source frequencies with respect to the untuned resonance frequency of the device. The time necessary for this prototype device to harvest the energy expended during its most energy-intensive (largest resonant frequency adjustment) tuning operation is 88 min in a low amplitude 0.1g vibration environment, which could be further optimized using higher efficiency piezoelectric materials and system components

  7. Fiber Bragg Grating vibration sensor with DFB laser diode

    Science.gov (United States)

    Siska, Petr; Brozovic, Martin; Cubik, Jakub; Kepak, Stanislav; Vitasek, Jan; Koudelka, Petr; Latal, Jan; Vasinek, Vladimir

    2012-01-01

    The Fiber Bragg Grating (FBG) sensors are nowadays used in many applications. Thanks to its quite big sensitivity to a surrounding environment, they can be used for sensing of temperature, strain, vibration or pressure. A fiber Bragg grating vibration sensor, which is interrogated by a distributed feedback laser diode (DFB) is demonstrated in this article. The system is based on the intensity modulation of the narrow spectral bandwidth of the DFB laser, when the reflection spectrum of the FBG sensor is shifted due to the strain that is applied on it in form of vibrations caused by acoustic wave pressure from loud speaker. The sensor's response in frequency domain and strain is measured; also the factor of sensor pre-strain impact on its sensitivity is discussed.

  8. Sum Frequency Generation Vibrational Spectroscopy of Colloidal Platinum Nanoparticle Catalysts: Disordering versus Removal of Organic Capping

    KAUST Repository

    Krier, James M.; Michalak, William D.; Baker, L. Robert; An, Kwangjin; Komvopoulos, Kyriakos; Somorjai, Gabor A.

    2012-01-01

    Recent work with nanoparticle catalysts shows that size and shape control on the nanometer scale influences reaction rate and selectivity. Sum frequency generation (SFG) vibrational spectroscopy is a powerful tool for studying heterogeneous

  9. Measurement of correlations between low-frequency vibrational modes and particle rearrangements in quasi-two-dimensional colloidal glasses.

    Science.gov (United States)

    Chen, Ke; Manning, M L; Yunker, Peter J; Ellenbroek, Wouter G; Zhang, Zexin; Liu, Andrea J; Yodh, A G

    2011-09-02

    We investigate correlations between low-frequency vibrational modes and rearrangements in two-dimensional colloidal glasses composed of thermosensitive microgel particles, which readily permit variation of the sample packing fraction. At each packing fraction, the particle displacement covariance matrix is measured and used to extract the vibrational spectrum of the "shadow" colloidal glass (i.e., the particle network with the same geometry and interactions as the sample colloid but absent damping). Rearrangements are induced by successive, small reductions in the packing fraction. The experimental results suggest that low-frequency quasilocalized phonon modes in colloidal glasses, i.e., modes that present low energy barriers for system rearrangements, are spatially correlated with rearrangements in this thermal system.

  10. Simultaneously Suppressing Low-Frequency and Relaxation Oscillation Intensity Noise in a DBR Single-Frequency Phosphate Fiber Laser

    International Nuclear Information System (INIS)

    Xiao Yu; Li Can; Xu Shan-Hui; Feng Zhou-Ming; Yang Chang-Sheng; Zhao Qi-Lai; Yang Zhong-Min

    2015-01-01

    Effective multiple optoelectronic feedback circuits for simultaneously suppressing low-frequency and relaxation oscillation intensity noise in a single-frequency phosphate fiber laser are demonstrated. The forward transfer function, which relates the laser output intensity to the pump modulations, is measured and analyzed. A custom two-path feedback system operating at different frequency bands is designed to adjust the pump current directly. The relative intensity noise is decreased by 20 dB from 0.2 to 5kHz and over 10 dB from 5 to 10 kHz. The relaxation oscillation peak is suppressed by 22 dB. In addition, a long term (24 h) laser instability of less than 0.05% is achieved. (paper)

  11. Diagnosis of industrial gearboxes condition by vibration and time-frequency, scale-frequency, frequency-frequency analysis

    Directory of Open Access Journals (Sweden)

    P. Czech

    2012-10-01

    Full Text Available In the article methods of vibroacoustic diagnostics of high-power toothed gears are described. It is shown below, that properly registered and processed acoustic signal or vibration signal may serve as an explicitly interpreted source of diagnostic symptoms. The presented analysis were based on vibration signals registered during the work of the gear of a rolling stand working in Katowice Steel Plant (presently one of the branches of Mittal Steel Poland JSC.

  12. Energy conversion by ‘T-shaped’ cantilever type electromagnetic vibration based micro power generator from low frequency vibration sources

    International Nuclear Information System (INIS)

    Siddique, Abu Raihan Mohammad; Mahmud, Shohel; Van Heyst, Bill

    2017-01-01

    Highlights: • A T-shaped cantilever type electromagnetic vibration based MPG has been described. • The designed EVMPG is useful for low frequency based vibration sources. • Both experimental tests and theoretical analysis have been performed. • The final compact prototype was tested at different conditions of human movements. • The prototype can generate 35.2 mV and 0.22 mW at 7 Hz with 5.6 Ω. - Abstract: The design, development, and analyses of low-frequency vibration based T-shaped cantilever type electromagnetic micro power generators (EVMPGs) are presented in this paper. Four different configurations (Configurations A to D) of EVMPGs were designed and fabricated and subsequently characterized using detailed experimental and limited analytical techniques. Configuration A and B consisted of a single and a double cylindrical moving magnets (NdFeB), respectively, while Configuration C consisted of four rectangular moving magnets with respect to a fixed copper coil. In contrast, Configuration D used a moving coil between four rectangular magnets with a back-iron bar. The open circuit RMS voltage output was observed to be a maximum from Configuration D (98.2 mV at 6.29 Hz) with a base vibration acceleration of 0.8 m s"−"2. Therefore, Configuration D was selected for further experimental investigations, which included changing the back-iron bar thickness, changing the base acceleration level, and changing the air gap separation between the magnets in order to optimize this configuration. The maximum load RMS voltage and power outputs of Configuration D were 105.4 mV and 1.35 mW at 6.29 Hz for load resistance 8.2 Ω and a base acceleration of 0.8 m s"−"2 with a 4.2 mm back-iron bar when the air gap between the magnets was 20 mm. Finally, a small portable EVMPG prototype was developed based on the Configuration D and was tested at different human movement conditions (i.e., walking, quick walking, and running). The developed EVMPG prototype was capable of

  13. THE POSSIBLE INTERSTELLAR ANION CH2CN–: SPECTROSCOPIC CONSTANTS, VIBRATIONAL FREQUENCIES, AND OTHER CONSIDERATIONS

    International Nuclear Information System (INIS)

    Fortenberry, Ryan C.; Lee, Timothy J.; Crawford, T. Daniel

    2013-01-01

    The A 1 B 1 ⇽ X-tilde 1 A' excitation into the dipole-bound state of the cyanomethyl anion (CH 2 CN – ) has been hypothesized as the carrier for one diffuse interstellar band. However, this particular molecular system has not been detected in the interstellar medium even though the related cyanomethyl radical and the isoelectronic ketenimine molecule have been found. In this study, we are employing the use of proven quartic force fields and second-order vibrational perturbation theory to compute accurate spectroscopic constants and fundamental vibrational frequencies for X-tilde 1 A' CH 2 CN – in order to assist in laboratory studies and astronomical observations.

  14. The Possible Interstellar Anion CH2CN-: Spectroscopic Constants, Vibrational Frequencies, and Other Considerations

    Science.gov (United States)

    Fortenberry, Ryan C.; Crawford, T. Daniel; Lee, Timothy J.

    2013-01-01

    The A\\ ^1B_1 \\leftarrow \\tilde{X}\\ ^1A^{\\prime } excitation into the dipole-bound state of the cyanomethyl anion (CH2CN-) has been hypothesized as the carrier for one diffuse interstellar band. However, this particular molecular system has not been detected in the interstellar medium even though the related cyanomethyl radical and the isoelectronic ketenimine molecule have been found. In this study, we are employing the use of proven quartic force fields and second-order vibrational perturbation theory to compute accurate spectroscopic constants and fundamental vibrational frequencies for \\tilde{X}\\ ^1A^{\\prime } CH2CN- in order to assist in laboratory studies and astronomical observations.

  15. Fingers' vibration transmission and grip strength preservation performance of vibration reducing gloves.

    Science.gov (United States)

    Hamouda, K; Rakheja, S; Dewangan, K N; Marcotte, P

    2018-01-01

    The vibration isolation performances of vibration reducing (VR) gloves are invariably assessed in terms of power tools' handle vibration transmission to the palm of the hand using the method described in ISO 10819 (2013), while the nature of vibration transmitted to the fingers is ignored. Moreover, the VR gloves with relatively low stiffness viscoelastic materials affect the grip strength in an adverse manner. This study is aimed at performance assessments of 12 different VR gloves on the basis of handle vibration transmission to the palm and the fingers of the gloved hand, together with reduction in the grip strength. The gloves included 3 different air bladder, 3 gel, 3 hybrid, and 2 gel-foam gloves in addition to a leather glove. Two Velcro finger adapters, each instrumented with a three-axis accelerometer, were used to measure vibration responses of the index and middle fingers near the mid-phalanges. Vibration transmitted to the palm was measured using the standardized palm adapter. The vibration transmissibility responses of the VR gloves were measured in the laboratory using the instrumented cylindrical handle, also described in the standard, mounted on a vibration exciter. A total of 12 healthy male subjects participated in the study. The instrumented handle was also used to measure grip strength of the subjects with and without the VR gloves. The results of the study showed that the VR gloves, with only a few exceptions, attenuate handle vibration transmitted to the fingers only in the 10-200 Hz and amplify middle finger vibration at frequencies exceeding 200 Hz. Many of the gloves, however, provided considerable reduction in vibration transmitted to the palm, especially at higher frequencies. These suggest that the characteristics of vibration transmitted to fingers differ considerably from those at the palm. Four of the test gloves satisfied the screening criteria of the ISO 10819 (2013) based on the palm vibration alone, even though these caused

  16. [Dynamics of vegetative indicators induced by low-frequency magnetotherapy and EHF-puncture in hypertensive workers exposed to vibration].

    Science.gov (United States)

    Drobyshev, V A; Efremov, A V; Loseva, M I; Sukharevskaia, T M; Michurin, A I

    2002-01-01

    Low-frequency magnetic fields and EHF-therapy have been used in correction of autonomic homeostasis in workers exposed to vibration for different periods of time. The workers suffered from early arterial hypertension. Vegetative status and central hemodynamics improved best in workers exposed to vibration for less than 5 years. If the exposure was 6-15 years, a positive trend occurred in the tension of regulatory mechanisms. Workers with long exposure to vibration suffering from vagotonia showed an inadequate response of the autonomic parameters to treatment. This necessitates enhancement of therapeutic measures with medicines.

  17. Natural Frequencies and Vibrating Modes for a Magnetic Planetary Gear Drive

    Directory of Open Access Journals (Sweden)

    Lizhong Xu

    2012-01-01

    Full Text Available In this paper, a dynamic model for a magnetic planetary gear drive is proposed. Based on the model, the dynamic equations for the magnetic planetary gear drive are given. From the magnetic meshing forces and torques between the elements for the drive system, the tangent and radial magnetic meshing stiffness is obtained. Using these equations, the natural frequencies and the modes of the magnetic planetary gear drive are investigated. The sensitivity of the natural frequencies to the system parameters is discussed. Results show that the pole pair number and the air gap have obvious effects on the natural frequencies. For the planetary gear number larger than two, the vibrations of the drive system include the torsion mode of the center elements, the translation mode of the center elements, and the planet modes. For the planetary gear number equal to two, the planet mode does not occur, the crown mode and the sun gear mode occur.

  18. Attitudes Toward, and Use of, Vibrators in China.

    Science.gov (United States)

    Jing, Shen; Lay, Alixe; Weis, Laura; Furnham, Adrian

    2018-01-02

    The current study examined the relationship between traditional masculine traits and attitudes toward vibrator use, actual vibrator use, and frequency of vibrator use in China. In all, 235 Chinese females aged between 16 and 58 years completed a questionnaire regarding attitudes toward, and personal use of, vibrators. The results showed a positive association between masculine traits and attitudes toward women's vibrator use, attitudes toward vibrator use and actual vibrator use, as well as frequency of vibrator use. The findings revealed an indirect path in which masculinity influences actual and frequency of vibrator use through attitudes toward women's vibrator use. Limitations and implications of the study are discussed.

  19. Algorithm for the calculation of vibration inherent frequencies bending from two-shafts transmission

    Directory of Open Access Journals (Sweden)

    Grigore Jan-Cristian

    2017-01-01

    Full Text Available The operation of the speed shaft transmissions at or near the natural frequency of the pulses at the resonance phenomenon leads to bending, when the amplitude of the oscillations increases sharply, causing deterioration or complete destruction thereof. To avoid system resonance operation is necessary to know the most accurate values its pulsations and taking appropriate constructive measures to avoid overlapping with disturbing frequency harmonics (operating speeds.This paper presents an algorithm for calculating the pulsation and vibration modes in bending, and based on numerical simulations performed on a real two-shafts transmission and will draw conclusions drawn diagrams.

  20. Transmission of High Frequency Vibrations in Rotating Systems. Application to Cavitation Detection in Hydraulic Turbines

    Directory of Open Access Journals (Sweden)

    David Valentín

    2018-03-01

    Full Text Available One of the main causes of damage in hydraulic turbines is cavitation. While not all cavitation appearing in a turbine is of a destructive type, erosive cavitation can severely affect the structure, thus increasing maintenance costs and reducing the remaining useful life of the machine. Of all types of cavitation, the maximum erosion occurs when clouds of bubbles collapse on the runner surface (cloud cavitation. When this occurs it is associated with a substantial increase in noise, and vibrations that are propagated everywhere throughout the machine. The generation of these cavitation clouds may occur naturally or it may be the response to a periodic pressure fluctuation, like the rotor/stator interaction in a hydraulic turbine. Erosive bubble cavitation generates high-frequency vibrations that are modulated by the shedding frequency. Therefore, the methods for the detection of erosive cavitation in hydraulic turbines are based on the measurement and demodulation of high-frequency vibrations. In this paper, the feasibility of detecting erosive cavitation in hydraulic turbines is investigated experimentally in a rotating disk system, which represents a simplified hydraulic turbine structure. The test rig used consists of a rotating disk submerged in a tank of water and confined with nearby axial and radial rigid surfaces. The excitation patterns produced by cloud cavitation are reproduced with a PZT (piezoelectric patch located on the disk. These patterns include pseudo-random excitations of different frequency bands modulated by one low carrier frequency, which model the erosive cavitation characteristics. Different types of sensors have been placed in the stationary and in the rotating parts (accelerometers, acoustic emission (AE, and a microphone in order to detect the excitation pattern. The results obtained for all the sensors tested have been compared in detail for the different excitation patterns applied to the disk. With this information

  1. Characteristics of low-frequency oscillation intensity of airsea turbulent heat fluxes over the northwest Pacific

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Based on the daily turbulent heat fluxes and related meteorological variables datasets (1985-2006) from Objectively Analyzed air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea humidity gradient (Δq′) as well as mean air-sea humidity gradient ( Δ q), while the distribution of low-frequency oscillation intensity of sensible heat flux (SHF) is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea temperature gradient (ΔT′). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those of low-frequency oscillation intensity of Δq′, low-frequency oscillation intensity of anomalous wind speed (U′), Δ q and mean wind speed (U ), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency oscillation intensity of ΔT′ and U . 3) Over the tropical west Pacific and sea areas north of 20°N, the low-frequency oscillation of LHF (SHF) is mainly influenced by atmospheric variables qa′ (Ta′) and U′, indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific south of 20°N, qs′ (Ts′) also greatly influences the low-frequency oscillation of LHF (SHF).

  2. intensity, duration and frequency of rainstorms in lokoja

    African Journals Online (AJOL)

    Shuaibu et al.

    This study analyzed the Intensity, duration and frequency (IDF) of rainstorms in Lokoja. ... INTRODUCTION. Rainfall worldwide has certain characteristics where it occurs. ..... State University of Science and Technology, Port. Harcourt, Nigeria.

  3. Frontside-micromachined planar piezoresistive vibration sensor: Evaluating performance in the low frequency test range

    Directory of Open Access Journals (Sweden)

    Lan Zhang

    2014-01-01

    Full Text Available Using a surface piezoresistor diffusion method and front-side only micromachining process, a planar piezoresistive vibration sensor was successfully developed with a simple structure, lower processing cost and fewer packaging difficulties. The vibration sensor had a large sector proof mass attached to a narrow flexure. Optimization of the boron diffusion piezoresistor placed on the edge of the narrow flexure greatly improved the sensitivity. Planar vibration sensors were fabricated and measured in order to analyze the effects of the sensor dimensions on performance, including the values of flexure width and the included angle of the sector. Sensitivities of fabricated planar sensors of 0.09–0.46 mV/V/g were measured up to a test frequency of 60 Hz. The sensor functioned at low voltages (<3 V and currents (<1 mA with a high sensitivity and low drift. At low background noise levels, the sensor had performance comparable to a commercial device.

  4. Frontside-micromachined planar piezoresistive vibration sensor: Evaluating performance in the low frequency test range

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lan; Lu, Jian, E-mail: jian-lu@aist.go.jp; Takagi, Hideki; Maeda, Ryutaro [Research Center for Ubiquitous MEMS and Micro Engineering (UMEMSME), National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki, 305-8564 (Japan)

    2014-01-15

    Using a surface piezoresistor diffusion method and front-side only micromachining process, a planar piezoresistive vibration sensor was successfully developed with a simple structure, lower processing cost and fewer packaging difficulties. The vibration sensor had a large sector proof mass attached to a narrow flexure. Optimization of the boron diffusion piezoresistor placed on the edge of the narrow flexure greatly improved the sensitivity. Planar vibration sensors were fabricated and measured in order to analyze the effects of the sensor dimensions on performance, including the values of flexure width and the included angle of the sector. Sensitivities of fabricated planar sensors of 0.09–0.46 mV/V/g were measured up to a test frequency of 60 Hz. The sensor functioned at low voltages (<3 V) and currents (<1 mA) with a high sensitivity and low drift. At low background noise levels, the sensor had performance comparable to a commercial device.

  5. Vibrational spectroscopy of shock-compressed fluid N2 and O2

    International Nuclear Information System (INIS)

    Schmidt, S.C.; Moore, D.S.; Shaw, M.S.; Johnson, J.D.

    1987-01-01

    Single-pulse multiplex coherent anti-Stokes Raman scattering (CARS) was used to observe the vibrational spectra of liquid N 2 shock-compressed to several pressures and temperatures up to 41 GPa and 5200 K and liquid O 2 shock-compressed to several pressures and temperatures up to 10 GPa and 1000 K. For N 2 , the experimental spectra were compared to synthetic spectra calculated using a semiclassical model for CARS intensities and estimated vibrational frequencies, peak Raman susceptibilities, and Raman line widths. The question of excited state populations in the shock-compressed state is addressed

  6. Grid Cell Relaxation Effects on the High Frequency Vibration Characteristics

    International Nuclear Information System (INIS)

    Ryu, Joo-Young; Eom, Kyong-Bo; Jeon, Sang-Youn; Kim, Jae-Ik

    2015-01-01

    The plate structure of the grid of fuel assembly is always exposed to serious vortex induced vibration. Also, High Frequency flow induced Vibration (HFV) is primarily generated by vortex-shedding effect. When it comes to grid design as a fuel assembly component, HFV should be considered in advance since it is one of the critical factors. Excessive HFV has a possibility of making degradation of the fuel reliability that is directly related to the fuel robustness and operating performance. KEPCO NF (KNF) has performed HFV tests with various grid designs. While studying the HFV characteristics through the HFV tests, it has been observed that HFV amplitudes show different levels according to grid cell relaxation. It means that the testing could give different interpretations due to the condition of grid cell. Since the amount of relaxation is different under operating conditions and environments in a reactor, test specimens should be modified as much as possible to the real state of the fuel. Therefore, in order to consider the grid cell relaxation effects on the HFV tests, it is important to use cell sized or non-cell sized grids. The main focus of this study is to find out how the HFV characteristics such as amplitude and frequency are affected by grid cell relaxation. Three cases of the grid cell sized specimen which is nickel alloy were prepared and tested. Through the comparison of the test results, it could be concluded that HFV amplitudes show decreasing trend according to the grid cell relaxation in the case of nickel alloy grid. It is also possible to expect the tendency of grid cell relaxation of a zirconium alloy grid based on test results

  7. Identification of Natural Frequency of Low Rise Building on Soft Ground Profile using Ambient Vibration Method

    Science.gov (United States)

    Kamarudin, A. F.; Zainal Abidin, M. H.; Mokhatar, S. N.; Daud, M. E.; Ibrahim, A.; Ibrahim, Z.; Noh, M. S. Md

    2018-04-01

    Natural frequency is the rate at which a body to vibrate or oscillate. Application of ambient vibration (AV) excitation is widely used nowadays as the input motion for building predominant frequency, fo, and ground fundamental frequency, Fo, prediction due to simple, fast, non-destructive, simple handling operation and reliable result. However, it must be emphasized and caution to isolate these frequencies (fo and Fo) from spurious frequencies of site-structure effects especially to low rise building on soft ground deposit. In this study, identification of fo and Fo by using AV measurements were performed on ground and 4-storey primary school reinforced concrete (RC) building at Sekolah Kebangsaan (SK) Sg. Tongkang, Rengit, Johor using 1 Hz of tri-axial seismometer sensor. Overlapping spectra between Fourier Amplitude Spectra (FAS) from and Horizontal to Vertical Spectra Ratio (HVSR) were used to distinguish respective frequencies of building and ground natural frequencies. Three dominant frequencies were identified from the FAS curves at 1.91 Hz, 1.98 Hz and 2.79 Hz in longitudinal (East West-EW), transverse (North South-NS) and vertical (UD) directions. It is expected the building has deformed in translational mode based on the first peak frequency by respective NS and EW components of FAS spectrum. Vertical frequency identified from the horizontal spectrums, might induces to the potential of rocking effect experienced by the school building. Meanwhile, single peak HVSR spectrum at low ground fundamental frequency concentrated at 0.93 Hz indicates to the existence deep contrast of soft deposit. Strong interaction between ground and building at similar frequency (0.93 Hz) observed from the FAS curves on the highest floor has shown the building to behave as a dependent unit against ground response as one rigid mass.

  8. Communication: Quantitative multi-site frequency maps for amide I vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Reppert, Mike [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States); Tokmakoff, Andrei, E-mail: tokmakoff@uchicago.edu [Department of Chemistry, University of Chicago, Chicago, Illinois 60637 (United States)

    2015-08-14

    An accurate method for predicting the amide I vibrational spectrum of a given protein structure has been sought for many years. Significant progress has been made recently by sampling structures from molecular dynamics simulations and mapping local electrostatic variables onto the frequencies of individual amide bonds. Agreement with experiment, however, has remained largely qualitative. Previously, we used dipeptide fragments and isotope-labeled constructs of the protein G mimic NuG2b as experimental standards for developing and testing amide I frequency maps. Here, we combine these datasets to test different frequency-map models and develop a novel method to produce an optimized four-site potential (4P) map based on the CHARMM27 force field. Together with a charge correction for glycine residues, the optimized map accurately describes both experimental datasets, with average frequency errors of 2–3 cm{sup −1}. This 4P map is shown to be convertible to a three-site field map which provides equivalent performance, highlighting the viability of both field- and potential-based maps for amide I spectral modeling. The use of multiple sampling points for local electrostatics is found to be essential for accurate map performance.

  9. Effect of vibration on muscle strength imbalance in lower extremity using multi-control whole body vibration platform.

    Science.gov (United States)

    Yu, Chang Ho; Seo, Shin Bae; Kang, Seung Rok; Kim, Kyung; Kwon, Tae Kyu

    2015-01-01

    This study shows the improvement of muscle activity and muscle strength imbalance in the lower extremities through independent exercise loads in vibration platform. Twenty females of age 20 participated in this study. The subjects were divided into WBV group, with more than 10% of muscle strength imbalance between left and right the lower extremities, and control group, with less than 10% of muscle strength imbalance between left and right the lower extremities. As the prior experiment showed, different exercise postures provide different muscular activities. As a result, the highest muscular activity was found to be in the low squat posture. Therefore, the LS posture was selected for the exercise in this experiment. Vibration intensities were applied to dominant muscle and non-dominant muscle, and the vibration frequency was fixed at 25Hz for the WBV group. The control group was asked to perform the same exercise as the WBV group, without stimulated vibration. This exercise was conducted for a total of 4 weeks. As a result, the WBV group which showed an average deviation of 16% before the experiment, tended to decrease approximately to 5%. In this study, vibration exercise using load deviation is shown to be effective in improving the muscle strength imbalance.

  10. Vibration of machine

    International Nuclear Information System (INIS)

    Kwak, Mun Gyu; Na, Sung Su; Baek, Gwang Hyeon; Song, Chul Gi; Han, Sang Bo

    2001-09-01

    This book deals with vibration of machine which gives descriptions of free vibration using SDOF system, forced vibration using SDOF system, vibration of multi-degree of freedom system like introduction and normal form, distribution system such as introduction, free vibration of bar and practice problem, approximate solution like lumped approximations and Raleigh's quotient, engineering by intuition and experience, real problem and experimental method such as technology of signal, fourier transform analysis, frequency analysis and sensor and actuator.

  11. Translational vibrations between chains of hydrogen-bonded molecules in solid-state aspirin form I

    Science.gov (United States)

    Takahashi, Masae; Ishikawa, Yoichi

    2013-06-01

    We perform dispersion-corrected first-principles calculations, and far-infrared (terahertz) spectroscopic experiments at 4 K, to examine translational vibrations between chains of hydrogen-bonded molecules in solid-state aspirin form I. The calculated frequencies and relative intensities reproduce the observed spectrum to accuracy of 11 cm-1 or less. The stronger one of the two peaks assigned to the translational mode includes the stretching vibration of the weak hydrogen bond between the acetyl groups of a neighboring one-dimensional chain. The calculation of aspirin form II performed for comparison gives the stretching vibration of the weak hydrogen bond in one-dimensional chain.

  12. Conformational, structural, vibrational and quantum chemical analysis on 4-aminobenzohydrazide and 4-hydroxybenzohydrazide--a comparative study.

    Science.gov (United States)

    Arjunan, V; Jayaprakash, A; Carthigayan, K; Periandy, S; Mohan, S

    2013-05-01

    Experimental and theoretical quantum chemical studies were carried out on 4-hydroxybenzohydrazide (4HBH) and 4-aminobenzohydrazide (4ABH) using FTIR and FT-Raman spectral data. The structural characteristics and vibrational spectroscopic analysis were carried performed by quantum chemical methods with the hybrid exchange-correlation functional B3LYP using 6-31G(**), 6-311++G(**) and aug-cc-pVDZ basis sets. The most stable conformer of the title compounds have been determined from the analysis of potential energy surface. The stable molecular geometries, electronic and thermodynamic parameters, IR intensities, harmonic vibrational frequencies, depolarisation ratio and Raman intensities have been computed. Molecular electrostatic potential and frontier molecular orbitals were constructed to understand the electronic properties. The potential energy distributions (PEDs) were calculated to explain the mixing of fundamental modes. The theoretical geometrical parameters and the fundamental frequencies were compared with the experimental. The interactions of hydroxy and amino group substitutions on the characteristic vibrations of the ring and hydrazide group have been analysed. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Sub-THz spectroscopic characterization of vibrational modes in artificially designed DNA monocrystal

    International Nuclear Information System (INIS)

    Sizov, Igor; Rahman, Masudur; Gelmont, Boris; Norton, Michael L.; Globus, Tatiana

    2013-01-01

    Highlights: • Sub-THz spectroscopy is used to characterize artificially designed DNA monocrystal. • Results are obtained using a novel near field, RT, frequency domain spectrometer. • Narrow resonances of 0.1 cm −1 width in absorption spectra of crystal are observed. • Signature measured between 310 and 490 GHz is reproducible and well resolved. • Absorption pattern is explained in part by simulation results from dsDNA fragment. - Abstract: Sub-terahertz (sub-THz) vibrational spectroscopy is a new spectroscopic branch for characterizing biological macromolecules. In this work, highly resolved sub-THz resonance spectroscopy is used for characterizing engineered molecular structures, an artificially designed DNA monocrystal, built from a short DNA sequence. Using a recently developed frequency domain spectroscopic instrument operating at room temperature with high spectral and spatial resolution, we demonstrated very intense and specific spectral lines from a DNA crystal in general agreement with a computational molecular dynamics (MD) simulation of a short double stranded DNA fragment. The spectroscopic signature measured in the frequency range between 310 and 490 GHz is rich in well resolved and reproducible spectral features thus demonstrating the capability of THz resonance spectroscopy to be used for characterizing custom macromolecules and structures designed and implemented via nanotechnology for a wide variety of application domains. Analysis of MD simulation indicates that intense and narrow vibrational modes with atomic movements perpendicular (transverse) and parallel (longitudinal) to the long DNA axis coexist in dsDNA, with much higher contribution from longitudinal vibrations

  14. Stochastic many-body perturbation theory for anharmonic molecular vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Hermes, Matthew R. [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); Hirata, So, E-mail: sohirata@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)

    2014-08-28

    A new quantum Monte Carlo (QMC) method for anharmonic vibrational zero-point energies and transition frequencies is developed, which combines the diagrammatic vibrational many-body perturbation theory based on the Dyson equation with Monte Carlo integration. The infinite sums of the diagrammatic and thus size-consistent first- and second-order anharmonic corrections to the energy and self-energy are expressed as sums of a few m- or 2m-dimensional integrals of wave functions and a potential energy surface (PES) (m is the vibrational degrees of freedom). Each of these integrals is computed as the integrand (including the value of the PES) divided by the value of a judiciously chosen weight function evaluated on demand at geometries distributed randomly but according to the weight function via the Metropolis algorithm. In this way, the method completely avoids cumbersome evaluation and storage of high-order force constants necessary in the original formulation of the vibrational perturbation theory; it furthermore allows even higher-order force constants essentially up to an infinite order to be taken into account in a scalable, memory-efficient algorithm. The diagrammatic contributions to the frequency-dependent self-energies that are stochastically evaluated at discrete frequencies can be reliably interpolated, allowing the self-consistent solutions to the Dyson equation to be obtained. This method, therefore, can compute directly and stochastically the transition frequencies of fundamentals and overtones as well as their relative intensities as pole strengths, without fixed-node errors that plague some QMC. It is shown that, for an identical PES, the new method reproduces the correct deterministic values of the energies and frequencies within a few cm{sup −1} and pole strengths within a few thousandths. With the values of a PES evaluated on the fly at random geometries, the new method captures a noticeably greater proportion of anharmonic effects.

  15. The effect of the condensed-phase environment on the vibrational frequency shift of a hydrogen molecule inside clathrate hydrates.

    Science.gov (United States)

    Powers, Anna; Scribano, Yohann; Lauvergnat, David; Mebe, Elsy; Benoit, David M; Bačić, Zlatko

    2018-04-14

    We report a theoretical study of the frequency shift (redshift) of the stretching fundamental transition of an H 2 molecule confined inside the small dodecahedral cage of the structure II clathrate hydrate and its dependence on the condensed-phase environment. In order to determine how much the hydrate water molecules beyond the confining small cage contribute to the vibrational frequency shift, quantum five-dimensional (5D) calculations of the coupled translation-rotation eigenstates are performed for H 2 in the v=0 and v=1 vibrational states inside spherical clathrate hydrate domains of increasing radius and a growing number of water molecules, ranging from 20 for the isolated small cage to over 1900. In these calculations, both H 2 and the water domains are treated as rigid. The 5D intermolecular potential energy surface (PES) of H 2 inside a hydrate domain is assumed to be pairwise additive. The H 2 -H 2 O pair interaction, represented by the 5D (rigid monomer) PES that depends on the vibrational state of H 2 , v=0 or v=1, is derived from the high-quality ab initio full-dimensional (9D) PES of the H 2 -H 2 O complex [P. Valiron et al., J. Chem. Phys. 129, 134306 (2008)]. The H 2 vibrational frequency shift calculated for the largest clathrate domain considered, which mimics the condensed-phase environment, is about 10% larger in magnitude than that obtained by taking into account only the small cage. The calculated splittings of the translational fundamental of H 2 change very little with the domain size, unlike the H 2 j = 1 rotational splittings that decrease significantly as the domain size increases. The changes in both the vibrational frequency shift and the j = 1 rotational splitting due to the condensed-phase effects arise predominantly from the H 2 O molecules in the first three complete hydration shells around H 2 .

  16. The effect of the condensed-phase environment on the vibrational frequency shift of a hydrogen molecule inside clathrate hydrates

    Science.gov (United States)

    Powers, Anna; Scribano, Yohann; Lauvergnat, David; Mebe, Elsy; Benoit, David M.; Bačić, Zlatko

    2018-04-01

    We report a theoretical study of the frequency shift (redshift) of the stretching fundamental transition of an H2 molecule confined inside the small dodecahedral cage of the structure II clathrate hydrate and its dependence on the condensed-phase environment. In order to determine how much the hydrate water molecules beyond the confining small cage contribute to the vibrational frequency shift, quantum five-dimensional (5D) calculations of the coupled translation-rotation eigenstates are performed for H2 in the v =0 and v =1 vibrational states inside spherical clathrate hydrate domains of increasing radius and a growing number of water molecules, ranging from 20 for the isolated small cage to over 1900. In these calculations, both H2 and the water domains are treated as rigid. The 5D intermolecular potential energy surface (PES) of H2 inside a hydrate domain is assumed to be pairwise additive. The H2-H2O pair interaction, represented by the 5D (rigid monomer) PES that depends on the vibrational state of H2, v =0 or v =1 , is derived from the high-quality ab initio full-dimensional (9D) PES of the H2-H2O complex [P. Valiron et al., J. Chem. Phys. 129, 134306 (2008)]. The H2 vibrational frequency shift calculated for the largest clathrate domain considered, which mimics the condensed-phase environment, is about 10% larger in magnitude than that obtained by taking into account only the small cage. The calculated splittings of the translational fundamental of H2 change very little with the domain size, unlike the H2 j = 1 rotational splittings that decrease significantly as the domain size increases. The changes in both the vibrational frequency shift and the j = 1 rotational splitting due to the condensed-phase effects arise predominantly from the H2O molecules in the first three complete hydration shells around H2.

  17. CONTRIBUTIONS TO THE STUDY OF THE VIBRATIONS FREQUENCY OF THE DRILL TOOL IN THE PROCESS OF MANUFACTURING THE BRONZE MATERIALS

    Directory of Open Access Journals (Sweden)

    Cosmin-Mihai MIRIŢOIU

    2013-05-01

    Full Text Available In this paper we present the experimental testings used to study the vibration of the drill tool, during the drilling of the bronze products. We have used the experimental setup presented in Miriţoiu (2013[1]. In this paper the vibrations are analyzed during the drilling on the universal lathe machines. The main purpose of to find a correlation between the cutting speed and the frequency of the vibration by using the experimental results and the regression analysis

  18. Reduction of low frequency vibration of truck driver and seating system through system parameter identification, sensitivity analysis and active control

    Science.gov (United States)

    Wang, Xu; Bi, Fengrong; Du, Haiping

    2018-05-01

    This paper aims to develop an 5-degree-of-freedom driver and seating system model for optimal vibration control. A new method for identification of the driver seating system parameters from experimental vibration measurement has been developed. The parameter sensitivity analysis has been conducted considering the random excitation frequency and system parameter uncertainty. The most and least sensitive system parameters for the transmissibility ratio have been identified. The optimised PID controllers have been developed to reduce the driver's body vibration.

  19. Low intensity vibration of ankle muscles improves balance in elderly persons at high risk of falling

    Science.gov (United States)

    Toosizadeh, Nima; Mohler, Jane

    2018-01-01

    In our study we examined postural performance of young healthy persons (HY), elderly healthy persons (HE), and elderly persons at high risk of falling (FR). Anterio-posterior (AP) and medio-lateral (ML) ankle and hip angular deviations, as well as linear displacements of the center of mass (COM) were assessed in persons standing with eyes either open or closed, while none, and 40 and 30 Hz vibrations were applied bilaterally to the ankle muscle gastrocnemius. During quiet standing with eyes open, balance parameters in FR group differed from those in healthy groups. ML ankle and hip angular deviations, as well as COM linear displacements were noticeably larger in FR group. During quiet standing with eyes closed, all balance parameters in participants of all groups had a clear trend to increase. During standing with eyes open, 40 Hz vibration increased all but one balance parameter within HY group, ankle angular deviations in HE group, but none in FR group. In response to 30 Hz vibration, only ankle angular deviations and COM linear displacements increased in HY group. There were no changes in both elderly groups. During standing with eyes closed, 40 and 30 Hz vibrations did not produce consistent changes in balance parameters in HY and HE groups. In FR persons, 40 Hz vibration did not change balance parameters. However, in FR groups, 30 Hz vibration decreased ankle and hip angular deviations, and COM linear displacements. The major result of the study is a finding that low intensity vibration of ankle muscles makes balance better in elderly persons at high risk of falling. This result is clinically relevant because it suggests that applying mild vibration to ankle muscles while standing and walking might benefit elderly persons, improving their postural performance and reducing a risk of unexpected falls. PMID:29579098

  20. Atomic beams probe surface vibrations

    International Nuclear Information System (INIS)

    Robinson, A.L.

    1982-01-01

    In the last two years, surface scientist have begun trying to obtain the vibrational frequencies of surface atoms in both insulating and metallic crystals from beams of helium atoms. It is the inelastic scattering that researchers use to probe surface vibrations. Inelastic atomic beam scattering has only been used to obtain vibrational frequency spectra from clean surfaces. Several experiments using helium beams are cited. (SC)

  1. Polymorph characterization of active pharmaceutical ingredients (APIs) using low-frequency Raman spectroscopy.

    Science.gov (United States)

    Larkin, Peter J; Dabros, Marta; Sarsfield, Beth; Chan, Eric; Carriere, James T; Smith, Brian C

    2014-01-01

    Polymorph detection, identification, and quantitation in crystalline materials are of great importance to the pharmaceutical industry. Vibrational spectroscopic techniques used for this purpose include Fourier transform mid-infrared (FT-MIR) spectroscopy, Fourier transform near-infrared (FT-NIR) spectroscopy, Raman spectroscopy, and terahertz (THz) and far-infrared (FIR) spectroscopy. Typically, the fundamental molecular vibrations accessed using high-frequency Raman and MIR spectroscopy or the overtone and combination of bands in the NIR spectra are used to monitor the solid-state forms of active pharmaceutical ingredients (APIs). The local environmental sensitivity of the fundamental molecular vibrations provides an indirect probe of the long-range order in molecular crystals. However, low-frequency vibrational spectroscopy provides access to the lattice vibrations of molecular crystals and, hence, has the potential to more directly probe intermolecular interactions in the solid state. Recent advances in filter technology enable high-quality, low-frequency Raman spectra to be acquired using a single-stage spectrograph. This innovation enables the cost-effective collection of high-quality Raman spectra in the 200-10 cm(-1) region. In this study, we demonstrate the potential of low-frequency Raman spectroscopy for the polymorphic characterization of APIs. This approach provides several benefits over existing techniques, including ease of sampling and more intense, information-rich band structures that can potentially discriminate among crystalline forms. An improved understanding of the relationship between the crystalline structure and the low-frequency vibrational spectrum is needed for the more widespread use of the technique.

  2. System Detects Vibrational Instabilities

    Science.gov (United States)

    Bozeman, Richard J., Jr.

    1990-01-01

    Sustained vibrations at two critical frequencies trigger diagnostic response or shutdown. Vibration-analyzing electronic system detects instabilities of combustion in rocket engine. Controls pulse-mode firing of engine and identifies vibrations above threshold amplitude at 5.9 and/or 12kHz. Adapted to other detection and/or control schemes involving simultaneous real-time detection of signals above or below preset amplitudes at two or more specified frequencies. Potential applications include rotating machinery and encoders and decoders in security systems.

  3. Vibration and acoustic frequency spectra for industrial process modeling using selective fusion multi-condition samples and multi-source features

    Science.gov (United States)

    Tang, Jian; Qiao, Junfei; Wu, ZhiWei; Chai, Tianyou; Zhang, Jian; Yu, Wen

    2018-01-01

    Frequency spectral data of mechanical vibration and acoustic signals relate to difficult-to-measure production quality and quantity parameters of complex industrial processes. A selective ensemble (SEN) algorithm can be used to build a soft sensor model of these process parameters by fusing valued information selectively from different perspectives. However, a combination of several optimized ensemble sub-models with SEN cannot guarantee the best prediction model. In this study, we use several techniques to construct mechanical vibration and acoustic frequency spectra of a data-driven industrial process parameter model based on selective fusion multi-condition samples and multi-source features. Multi-layer SEN (MLSEN) strategy is used to simulate the domain expert cognitive process. Genetic algorithm and kernel partial least squares are used to construct the inside-layer SEN sub-model based on each mechanical vibration and acoustic frequency spectral feature subset. Branch-and-bound and adaptive weighted fusion algorithms are integrated to select and combine outputs of the inside-layer SEN sub-models. Then, the outside-layer SEN is constructed. Thus, "sub-sampling training examples"-based and "manipulating input features"-based ensemble construction methods are integrated, thereby realizing the selective information fusion process based on multi-condition history samples and multi-source input features. This novel approach is applied to a laboratory-scale ball mill grinding process. A comparison with other methods indicates that the proposed MLSEN approach effectively models mechanical vibration and acoustic signals.

  4. Bandwidth Widening of Piezoelectric Cantilever Beam Arrays by Mass-Tip Tuning for Low-Frequency Vibration Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Eduard Dechant

    2017-12-01

    Full Text Available Wireless sensor networks usually rely on internal permanent or rechargeable batteries as a power supply, causing high maintenance efforts. An alternative solution is to supply the entire system by harvesting the ambient energy, for example, by transducing ambient vibrations into electric energy by virtue of the piezoelectric effect. The purpose of this paper is to present a simple engineering approach for the bandwidth optimization of vibration energy harvesting systems comprising multiple piezoelectric cantilevers (PECs. The frequency tuning of a particular cantilever is achieved by changing the tip mass. It is shown that the bandwidth enhancement by mass tuning is limited and requires several PECs with close resonance frequencies. At a fixed frequency detuning between subsequent PECs, the achievable bandwidth shows a saturation behavior as a function of the number of cantilevers used. Since the resonance frequency of each PEC is different, the output voltages at a particular excitation frequency have different amplitudes and phases. A simple power-transfer circuit where several PECs with an individual full wave bridge rectifier are connected in parallel allows one to extract the electrical power close to the theoretical maximum excluding the diode losses. The experiments performed on two- and three-PEC arrays show reasonable agreement with simulations and demonstrate that this power-transfer circuit additionally influences the frequency dependence of the harvested electrical power.

  5. Vibrational Stability of SRF Accelerator Test Facility at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    McGee, M.W.; Volk, J.T.; /Fermilab

    2009-05-01

    Recently developed, the Superconducting Radio Frequency (SRF) Accelerator Test Facilities at Fermilab support the International Linear Collider (ILC), High Intensity Neutrino Source (HINS), a new high intensity injector (Project X) and other future machines. These facilities; Meson Detector Building (MDB) and New Muon Lab (NML) have very different foundations, structures, relative elevations with respect to grade level and surrounding soil composition. Also, there are differences in the operating equipment and their proximity to the primary machine. All the future machines have stringent operational stability requirements. The present study examines both near-field and ambient vibration in order to develop an understanding of the potential contribution of near-field sources (e.g. compressors, ultra-high and standard vacuum equipment, klystrons, modulators, utility fans and pumps) and distant noise sources to the overall system displacements. Facility vibration measurement results and methods of possible isolation from noise sources are presented and discussed.

  6. Vibration mixer

    Energy Technology Data Exchange (ETDEWEB)

    Alekhin, S.A.; Chernov, V.S.; Denisenko, V.V.; Gorodnyanskiy, I.F.; Prokopov, L.I.; Tikhonov, Yu.P.

    1983-01-01

    The vibration mixer is proposed which contains a housing, vibration drive with rod installed in the upper part of the mixing mechanism made in the form of a hollow shaft with blades. In order to improve intensity of mixing and dispersion of the mud, the shaft with the blades is arranged on the rod of the vibrator and is equipped with a cam coupling whose drive disc is attached to the vibration rod. The rod is made helical, while the drive disc of the cam coupling is attached to the helical surface of the rod. In addition, the vibration mixer is equipped with perforated discs installed on the ends of the rods.

  7. Numerical calculation of acoustic radiation from band-vibrating structures via FEM/FAQP method

    Directory of Open Access Journals (Sweden)

    GAO Honglin

    2017-08-01

    Full Text Available The Finite Element Method (FEM combined with the Frequency Averaged Quadratic Pressure method (FAQP are used to calculate the acoustic radiation of structures excited in the frequency band. The surface particle velocity of stiffened cylindrical shells under frequency band excitation is calculated using finite element software, the normal vibration velocity is converted from the surface particle velocity to calculate the average energy source (frequency averaged across intensity, frequency averaged across pressure and frequency averaged across velocity, and the FAQP method is used to calculate the average sound pressure level within the bandwidth. The average sound pressure levels are then compared with the bandwidth using finite element and boundary element software, and the results show that FEM combined with FAQP is more suitable for high frequencies and can be used to calculate the average sound pressure level in the 1/3 octave band with good stability, presenting an alternative to applying frequency-by-frequency calculation and the average frequency process. The FEM/FAQP method can be used as a prediction method for calculating acoustic radiation while taking the randomness of vibration at medium and high frequencies into consideration.

  8. Characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific

    Institute of Scientific and Technical Information of China (English)

    LI Gen; REN BaoHua; ZHENG JianOiu; WANG Jun

    2009-01-01

    Based on the daily turbulent heat fluxes and related meteorological variables dataeets (1985-2006) from Objectively Analyzed air-sea Fluxes (OAFlux) Project of Woods Hole Oceanographic Institution (WHOI), characteristics of low-frequency oscillation intensity of air-sea turbulent heat fluxes over the northwest Pacific are analyzed by linear perturbation method and correlation analysis. It can be concluded that: 1) the distribution of low-frequency oscillation intensity of latent heat flux (LHF) over the northwest Pacific is mainly affected by that of low-frequency oscillation intensity of anomalous air-eea humidity gradient (△q') as well as mean air-eea humidity gradient (△q), while the distribution of low-frequency oscillation Intensity of sensible heat flux (SHF) is mainly affected by that of low-frequency oscillation intensity of anomalous air-sea temperature gradient (△T'). 2) The low-frequency oscillation of turbulent heat fluxes over the northwest Pacific is the strongest in winter and the weakest in summer. And the seasonal transition of low-frequency oscillation intensity of LHF is jointly influenced by those of low-frequency oscillation intensity of △q', low-frequency oscillation intensity of anomalous wind speed (U'), △q and mean wind speed (U), while the seasonal transition of low-frequency oscillation intensity of SHF is mainly influenced by those of low-frequency oscillation Intensity of △T' and U. 3) Over the tropical west Pacific and sea areas north of 20ON, the low-frequency oscillation of LHF (SHF) is mainly influenced by atmospheric variables qa' (Ta') and U', indicating an oceanic response to overlying atmospheric forcing. In contrast, over the tropical eastern and central Pacific south of 20°N, qs' (Ts') also greatly influences the low-frequency oscillation of LHF (SHF).

  9. Dispersion-corrected first-principles calculation of terahertz vibration, and evidence for weak hydrogen bond formation

    Science.gov (United States)

    Takahashi, Masae; Ishikawa, Yoichi; Ito, Hiromasa

    2013-03-01

    A weak hydrogen bond (WHB) such as CH-O is very important for the structure, function, and dynamics in a chemical and biological system WHB stretching vibration is in a terahertz (THz) frequency region Very recently, the reasonable performance of dispersion-corrected first-principles to WHB has been proven. In this lecture, we report dispersion-corrected first-principles calculation of the vibrational absorption of some organic crystals, and low-temperature THz spectral measurement, in order to clarify WHB stretching vibration. The THz frequency calculation of a WHB crystal has extremely improved by dispersion correction. Moreover, the discrepancy in frequency between an experiment and calculation and is 10 1/cm or less. Dispersion correction is especially effective for intermolecular mode. The very sharp peak appearing at 4 K is assigned to the intermolecular translational mode that corresponds to WHB stretching vibration. It is difficult to detect and control the WHB formation in a crystal because the binding energy is very small. With the help of the latest intense development of experimental and theoretical technique and its careful use, we reveal solid-state WHB stretching vibration as evidence for the WHB formation that differs in respective WHB networks The research was supported by the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant No. 22550003).

  10. Self-excited multi-scale skin vibrations probed by optical tracking micro-motions of tracers on arms

    Science.gov (United States)

    Chen, Wei-Chia; Chen, Hsiang-Ying; Chen, Yu-Sheng; Tian, Yong; I, Lin

    2017-07-01

    The self-excited multi-scale mechanical vibrations, their sources and their mutual coupling of different regions on the forearms of supine subjects, are experimentally investigated, using a simple noncontact method, optical video microscopy, which provides 1 μm and 25 ms spatiotemporal resolutions. It is found that, in proximal regions far from the radial artery, the vibrations are the global vibrations of the entire forearm excited by remote sources, propagating through the trunk and the limb. The spectrum is mainly composed of peaks of very low frequency motion (down to 0.05 Hz), low frequency respiration modes, and heartbeat induced modes (about 1 Hz and its harmonics), standing out of the spectrum floor exhibiting power law decay. The nonlinear mode-mode coupling leads to the cascaded modulations of higher frequency modes by lower frequency modes. The nearly identical waveforms without detectable phase delays for a pair of signals along or transverse to the meridian of regions far away from the artery rule out the detectable contribution from the propagation of Qi, some kind of collective excitation which more efficiently propagates along meridians, according to the Chinese medicine theory. Around the radial artery, in addition to the global vibration, the local vibration spectrum shows very slow breathing type vibration around 0.05 Hz, and the artery pulsation induced fundamental and higher harmonics with descending intensities up to the fifth harmonics, standing out of a flat spectrum floor. All the artery pulsation modes are also modulated by respiration and the very slow vibration.

  11. Vibrational frequency scaling factors for correlation consistent basis sets and the methods CC2 and MP2 and their spin-scaled SCS and SOS variants

    Energy Technology Data Exchange (ETDEWEB)

    Friese, Daniel H., E-mail: daniel.h.friese@uit.no [Centre for Theoretical and Computational Chemistry CTCC, Department of Chemistry, University of Tromsø, N-9037 Tromsø (Norway); Törk, Lisa; Hättig, Christof, E-mail: christof.haettig@rub.de [Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44801 Bochum (Germany)

    2014-11-21

    We present scaling factors for vibrational frequencies calculated within the harmonic approximation and the correlated wave-function methods coupled cluster singles and doubles model (CC2) and Møller-Plesset perturbation theory (MP2) with and without a spin-component scaling (SCS or spin-opposite scaling (SOS)). Frequency scaling factors and the remaining deviations from the reference data are evaluated for several non-augmented basis sets of the cc-pVXZ family of generally contracted correlation-consistent basis sets as well as for the segmented contracted TZVPP basis. We find that the SCS and SOS variants of CC2 and MP2 lead to a slightly better accuracy for the scaled vibrational frequencies. The determined frequency scaling factors can also be used for vibrational frequencies calculated for excited states through response theory with CC2 and the algebraic diagrammatic construction through second order and their spin-component scaled variants.

  12. Spectral intensities in cubic systems. I. Progressions based upon parity vibrational modes

    International Nuclear Information System (INIS)

    Acevedo, R.; Vasquez, S.O.; Meruane, T.; Poblete, V.; Pozo, J.

    1998-01-01

    The well-resolved emission and absorption spectra of centrosymmetric coordination compounds of the transition metal ions have been used widely to provide the experimental data against which to test theoretical models of vibronic intensities. With reference to the 2 E g → 4 A 2g luminescence transition, at a perfect octahedral site in Cs 2 SiF 6 , over than one hundred vibronic lines are observed with line widths of a few wavenumber spread over some 3000 cm -1 . This paper reports a through examination of both the electronic and vibrational factors, which influences the observed vibronic intensities of the various assigned and identified lines in the spectra of the MnF 6 2- complex ion in the Cs 2 SiF 6 cubic lattice. The origin and nature of higher order vibronic interactions are analysed on the basis of a symmetrized vibronic crystal field-ligand polarization model. (Author)

  13. Natural vibration experimental analysis of Novovoronezhskaya NPP main building

    International Nuclear Information System (INIS)

    Zoubkov, D.; Isaikin, A.; Shablinsky, G.; Lopanchuk, A.; Nefedov, S.

    2005-01-01

    1. Natural vibration frequencies are main characteristics of buildings and structures which allow to give integral estimation of their in-service state. Even relatively small changes of these frequencies as compared to the initially registered values point to serious defects of building structures. In this paper we analyzed natural vibration frequencies and natural modes of the main building (MB) of Novovoronezhskaya NPP operating nuclear unit with WWER-440 type reactor. The MB consists of a reactor compartment (RC), a machine room (MR) and an electric device (ED) unit positioned in between. 2. Natural vibration frequencies and natural modes of the MB were determined experimentally by analyzing its microvibrations caused by operation of basic equipment (turbines, pumps, etc.). Microvibrations of the main building were measured at 12 points. At each point measurements were carried out along two or three mutually perpendicular vibration directions. Spectral analysis of vibration records has been conducted. Identification of natural vibration frequencies was carried out on the basis of the spectral peaks and plotted vibration modes (taking into account operating frequencies of the basic equipment of the power generating unit). On the basis of the measurement results three transverse modes and corresponding natural vibration frequencies of the MB, one longitudinal mode and corresponding natural vibration frequency of the MB and two natural frequencies of vertical vibrations of RC and MR floor trusses (1st and 2nd symmetric forms) were determined. Dynamic characteristics of the main building of NV NPP resulting from full scale researches are supposed to be used as one of building structure stability criteria. (authors)

  14. Measurement of correlations between low-frequency vibrational modes and particle rearrangements in quasi-two-dimensional colloidal glasses

    NARCIS (Netherlands)

    Chen, K.; Manning, M.L.; Yunker, P.J.; Ellenbroek, W.G.; Zhang, Zexin; Liu, Andrea J.; Yodh, A.G.

    2011-01-01

    We investigate correlations between low-frequency vibrational modes and rearrangements in two-dimensional colloidal glasses composed of thermosensitive microgel particles, which readily permit variation of the sample packing fraction. At each packing fraction, the particle displacement covariance

  15. Intensity and frequency stabilization of a laser diode by simultaneously controlling its temperature and current

    Science.gov (United States)

    Mu, Weiwei; Hu, Zhaohui; Wang, Jing; Zhou, Binquan

    2017-10-01

    Nuclear magnetic resonance gyroscope (NMRG) detects the angular velocity of the vehicle utilizing the interaction between the laser beam and the alkali metal atoms along with the noble gas atoms in the alkali vapor cell. In order to reach high precision inertial measurement target, semiconductor laser in NMRG should have good intensity and frequency stability. Generally, laser intensity and frequency are stabilized separately. In this paper, a new method to stabilize laser intensity and frequency simultaneously with double-loop feedback control is presented. Laser intensity is stabilized to the setpoint value by feedback control of laser diode's temperature. Laser frequency is stabilized to the Doppler absorption peak by feedback control of laser diode's current. The feedback control of current is a quick loop, hence the laser frequency stabilize quickly. The feedback control of temperature is a slow loop, hence the laser intensity stabilize slowly. With the feedback control of current and temperature, the laser intensity and frequency are stabilized finally. Additionally, the dependence of laser intensity and frequency on laser diode's current and temperature are analyzed, which contributes to choose suitable operating range for the laser diode. The advantage of our method is that the alkali vapor cell used for stabilizing laser frequency is the same one as the cell used for NMRG to operate, which helps to miniaturize the size of NMRG prototype. In an 8-hour continuous measurement, the long-term stability of laser intensity and frequency increased by two orders of magnitude and one order of magnitude respectively.

  16. Potassium-cobalt sulphate crystal growth assisted by low frequency vibrations

    Science.gov (United States)

    Sadovsky, A.; Ermochenkov, I.; Dubovenko, E.; Sukhanova, E.; Bebyakin, M.; Dubov, V.; Avetissov, I.

    2018-02-01

    Single crystals of K2Co(SO4)2·6H2O were grown from solution using the temperature reduction method enhanced by the axial low frequency vibration control technique (AVC-technique). Physical modeling of heat-mass transfer in solution under the AVC action was performed. The growth rate of the AVC grown crystal was found to be twice that of the crystal grown under natural convection conditions. Analysis of spectral characteristics (absorption and Raman spectra) as well as structural properties (dislocation density and microhardness) of the grown crystals showed the significant superiority of the AVC technique for the growth of K2Co(SO4)2·6H2O crystals.

  17. Surprising performance for vibrational frequencies of the distinguishable clusters with singles and doubles (DCSD) and MP2.5 approximations

    Science.gov (United States)

    Kesharwani, Manoj K.; Sylvetsky, Nitai; Martin, Jan M. L.

    2017-11-01

    We show that the DCSD (distinguishable clusters with all singles and doubles) correlation method permits the calculation of vibrational spectra at near-CCSD(T) quality but at no more than CCSD cost, and with comparatively inexpensive analytical gradients. For systems dominated by a single reference configuration, even MP2.5 is a viable alternative, at MP3 cost. MP2.5 performance for vibrational frequencies is comparable to double hybrids such as DSD-PBEP86-D3BJ, but without resorting to empirical parameters. DCSD is also quite suitable for computing zero-point vibrational energies in computational thermochemistry.

  18. Fatigue of 1 {mu}m-scale gold by vibration with reduced resonant frequency

    Energy Technology Data Exchange (ETDEWEB)

    Sumigawa, Takashi, E-mail: sumigawa@cyber.kues.kyoto-u.ac.jp [Department of Mechanical Engineering and Science, Kyoto University, Yoshidahommachi, Sakyo-ku, Kyoto 606-8501 (Japan); Matsumoto, Kenta [Department of Mechanical Engineering and Science, Kyoto University, Yoshidahommachi, Sakyo-ku, Kyoto 606-8501 (Japan); Tsuchiya, Toshiyuki [Department of Micro Engineering, Kyoto University, Yoshidahommachi, Sakyo-ku, Kyoto 606-8501 (Japan); Kitamura, Takayuki [Department of Mechanical Engineering and Science, Kyoto University, Yoshidahommachi, Sakyo-ku, Kyoto 606-8501 (Japan)

    2012-10-30

    In order to investigate the fatigue strength of micro-metal (1 {mu}m-scale), a testing method using resonant vibration is developed. Although the loading by vibration can solve the difficulties associated with the fatigue experiment of micro-specimen (e.g., specimen gripping and high-cycle loading under tension-compression), it inherently has an excessively high resonance frequency (more than several GHz at least) in a 1 {mu}m-scale metal specimen. For control of the fatigue cycle, the resonance frequency must be reduced to several hundreds of kHz by tuning the specimen shape. We design a cantilever specimen of 1 {mu}m scale gold with a weight at the tip, which reduces the resonant frequency to about 330 kHz. The unique specimen with the test section of 1.26 {mu}m Multiplication-Sign 0.94 {mu}m Multiplication-Sign 1.52 {mu}m is successfully fabricated by a novel technique using a focused ion beam and the tension-compression fatigue cycle is applied to it by means of a piezoelectric actuator. The test section breaks at about 1.6 Multiplication-Sign 10{sup 6} cycles under {Delta}{sigma}/2=230 MPa, which is within the targeted range of this project. It is easy to extend this method to high-cycle fatigue for actual use (including the failure cycles of over 10{sup 8} cycles). The slip bands observed on the surface, which have concavity and convexity similar to the intrusions/extrusions of PSBs, indicate that the failure is induced by the fatigue.

  19. Portable vibration exciter

    Science.gov (United States)

    Beecher, L. C.; Williams, F. T.

    1970-01-01

    Gas-driven vibration exciter produces a sinusoidal excitation function controllable in frequency and in amplitude. It allows direct vibration testing of components under normal loads, removing the possibility of component damage due to high static pressure.

  20. A search for optimal parameters of resonance circuits ensuring damping of electroelastic structure vibrations based on the solution of natural vibration problem

    Science.gov (United States)

    Oshmarin, D.; Sevodina, N.; Iurlov, M.; Iurlova, N.

    2017-06-01

    In this paper, with the aim of providing passive control of structure vibrations a new approach has been proposed for selecting optimal parameters of external electric shunt circuits connected to piezoelectric elements located on the surface of the structure. The approach is based on the mathematical formulation of the natural vibration problem. The results of solution of this problem are the complex eigenfrequencies, the real part of which represents the vibration frequency and the imaginary part corresponds to the damping ratio, characterizing the rate of damping. A criterion of search for optimal parameters of the external passive shunt circuits, which can provide the system with desired dissipative properties, has been derived based on the analysis of responses of the real and imaginary parts of different complex eigenfrequencies to changes in the values of the parameters of the electric circuit. The efficiency of this approach has been verified in the context of natural vibration problem of rigidly clamped plate and semi-cylindrical shell, which is solved for series-connected and parallel -connected external resonance (consisting of resistive and inductive elements) R-L circuits. It has been shown that at lower (more energy-intensive) frequencies, a series-connected external circuit has the advantage of providing lower values of the circuit parameters, which renders it more attractive in terms of practical applications.

  1. VIBRATION ANALYSIS OF TURBINE BASED ON FLUID-STRUCTURE COUPLING

    Institute of Scientific and Technical Information of China (English)

    LIU Demin; LIU Xiaobing

    2008-01-01

    The vibration of a Francis turbine is analyzed with the additional quality matrix method based on fluid-structure coupling (FSC). Firstly, the vibration frequency and mode of blade and runner in air and water are calculated. Secondly, the influences to runner frequency domain by large flow, small flow and design flow working conditions are compared. Finally the influences to runner modes by centrifugal forces under three rotating speeds of 400 r/min, 500 r/min and 600 r/min are compared. The centrifugal force and small flow working condition have greatly influence on the vibration of small runner. With the increase of centrifugal force, the vibration frequency of the runner is sharply increased. Some order frequencies are even close to the runner natural frequency in the air. Because the low frequency vibration will severely damage the stability of the turbine, low frequency vibration of units should be avoided as soon as possible.

  2. Efficient cooling of quantized vibrations using a four-level configuration

    Science.gov (United States)

    Yan, Lei-Lei; Zhang, Jian-Qi; Zhang, Shuo; Feng, Mang

    2016-12-01

    Cooling vibrational degrees of freedom down to ground states is essential to observation of quantum properties of systems with mechanical vibration. We propose two cooling schemes employing four internal levels of the systems, which achieve the ground-state cooling in an efficient fashion by completely deleting the carrier and first-order blue-sideband transitions. The schemes, based on quantum interference and Stark-shift gates, are robust to fluctuations of laser intensity and frequency. The feasibility of the schemes is justified using current laboratory technology. In practice, our proposal readily applies to a nanodiamond nitrogen-vacancy center levitated in an optical trap or attached to a cantilever.

  3. Natural frequencies and forms of flexural vibrations of a beam with a crack

    Directory of Open Access Journals (Sweden)

    Gordon Vladimir Aleksandrovich

    2014-03-01

    Full Text Available In view of providing durability of constructions, the urgent problem is studying dynamic processes in loaded rod structures occurring in the process of sudden local defects formation, such as breakage of support bonds, partial destruction, transverse and longitudinal cracks etc., which are united under general term "beyond design impacts". To date, a number of problems related to this topic are solved: the problem of dynamic loadings at sudden formation of transverse cracks, the problem of partial tie breaks in the bearings, partial destruction and longitudinal lamination of compound bars. In the paper the authors propose a method of determining the spectrum of natural frequencies of flexural vibrations of a rod system with this type of injury. The results are to be used for modal analysis of forced vibrations of a beam with a defect of longitudinal lamination, depending on its level.

  4. Development of Non-Conservative Joints in Beam Networks for Vibration Energy Flow Analysis

    Directory of Open Access Journals (Sweden)

    Jee-Hun Song

    2007-01-01

    Full Text Available Our work aims to find a general solution for the vibrational energy flow through a plane network of beams on the basis of an energy flow analysis. A joint between two semi-infinite beams are modeled by three sets of springs and dashpots. Thus, the results can incorporate the case of complaint and non-conservative in all the three degrees of freedom. In the cases of finite coupled structures connected at a certain angle, the derived non-conservative joints and developed wave energy equation were applied. The joint properties, the frequency, the coupling angle, and the internal loss factor were changed to evaluate the proposed methods for predicting medium-to-high frequency vibrational energy and intensity distributions.

  5. Vibrational collapse of boroxol rings in compacted B2O3 glasses: a study of Raman scattering and low temperature specific heat

    Science.gov (United States)

    Carini, Giovanni, Jr.; Carini, Giuseppe; D’Angelo, Giovanna; Federico, Mauro; Romano, Valentino

    2018-05-01

    Low and high frequency Raman scattering of B2O3 glasses, compacted under GPa pressures, has been performed to investigate structural changes due to increasing atomic packing. Compacted glasses, annealed at ambient temperature and pressure, experience a time-dependent decrease of the density to a smaller constant value over a period of few months, displaying a permanent plastic deformation. Increasing densification determines a parallel and progressive decrease of the intensity of the Boson peak and the main band at 808 cm‑1, both these modes arising from localized vibrations involving planar boroxol rings (B3O6), the glassy units formed from three basic BO3 triangles. The 808 cm‑1 mode preserves its frequency, while the BP evidences a well-defined frequency increase. The high-frequency multicomponent band between 1200 and 1600 cm‑1 also changes with increasing densification, disclosing a decreasing intensity of the 1260 cm‑1 mode due to oxygen vibrations of BO3 units bridging boroxol rings. This indicates the gradual vibrational collapse of groups formed from rings connected by more complex links than a single bridging oxygen. The observed behaviours suggest that glass compaction causes severe deformation of boroxol rings, determining a decrease of groups which preserve unaltered their vibrational activity. Growing glass densification stiffens the network and leads to a decrease of the excess heat capacity over the Debye prediction below 20 K, which is not accounted for by the hardening of the elastic continuum. By using the low-frequency Raman scattering to determine the temperature dependence of the heat capacity, it has been evaluated the density of low-frequency vibrational states which discloses a significant reduction of excess modes with increasing density.

  6. Fermi resonance effects on the vibration modes of hydrogen-passivated boron in silicon

    International Nuclear Information System (INIS)

    Watkins, G.D.; Fowler, W.B.; Deleo, G.G.; Stavola, M.; Kozuch, D.M.; Pearton, S.J.; Lopata, J.

    1990-01-01

    10 B - 11 B isotope shifts have been reported recently for the vibrational frequencies of hydrogen (H) and its isotope deuterium (D) in the H-B complex in silicon. The D- 10 B-D 11 B shift was found to be anomalously large. The authors show that this effect finds a natural explanation in a phenomenon called Fermi resonance, arising from a weak anharmonic coupling between the second harmonic of the transverse B vibration and the longitudinal D vibration. The authors present a simple classical explanation of the effect in terms of a parametric oscillator, or a child pumping a swing. They outline a simple quantum mechanical treatment that provides a satisfactory quantitative explanation of the results. The author's calculations also predict infrared absorption at the boron second harmonic frequencies. These are observed for both 10 B and 11 B with intensities and polarization as predicted, providing direct confirmation of the interpretation. The Pankove Si-H-B model, therefore, remains intact

  7. Phosphate vibrations as reporters of DNA hydration

    Science.gov (United States)

    Corcelli, Steven

    The asymmetric phosphate stretch vibrational frequency is extraordinarily sensitive to its local solvent environment. Using density functional theory calculations on the model compound dimethyl phosphate, the asymmetric phosphate stretch vibrational frequency was found to shift linearly with the magnitude of an electric field along the symmetry axis of the PO2 moiety (i.e. the asymmetric phosphate stretch is an excellent linear vibrational Stark effect probe). With this linear relationship established, asymmetric phosphate stretch vibrational frequencies were computed during the course of a molecular dynamics simulation of fully hydrated DNA. Moreover, contributions to shifts in the frequencies from subpopulations of water molecules (e.g. backbone, minor groove, major groove, etc.) were calculated to reveal how phosphate vibrations report the onset of DNA hydration in experiments that vary the relative humidity of non-condensing (dry) DNA samples.

  8. Vibrational and electronic spectroscopic studies of melatonin

    Science.gov (United States)

    Singh, Gurpreet; Abbas, J. M.; Dogra, Sukh Dev; Sachdeva, Ritika; Rai, Bimal; Tripathi, S. K.; Prakash, Satya; Sathe, Vasant; Saini, G. S. S.

    2014-01-01

    We report the infrared absorption and Raman spectra of melatonin recorded with 488 and 632.8 nm excitations in 3600-2700 and 1700-70 cm-1 regions. Further, we optimized molecular structure of the three conformers of melatonin within density functional theory calculations. Vibrational frequencies of all three conformers have also been calculated. Observed vibrational bands have been assigned to different vibrational motions of the molecules on the basis of potential energy distribution calculations and calculated vibrational frequencies. Observed band positions match well with the calculated values after scaling except Nsbnd H stretching mode frequencies. It is found that the observed and calculated frequencies mismatch of Nsbnd H stretching is due to intermolecular interactions between melatonin molecules.

  9. Spectral intensities in cubic systems. I. Progressions based upon parity vibrational modes

    Energy Technology Data Exchange (ETDEWEB)

    Acevedo, R.; Vasquez, S.O. [Department of Basic Chemistry, Faculty of Physical and Mathematical Sciences, University of Chile. Tupper 2069, Casilla 2777, Santiago, Chile (Chile); Meruane, T. [Department of Chemistry, Universidad Metropolitana de Ciencias de la Educacion. Av. J.P. Alessandri 774, Casilla 147, C. Santiago, Chile (Chile); Poblete, V. [Department of Nuclear Materials, Lo Aguirre, Comision Chilena de Energia Nuclear. Amunategui 95, Casilla 188-D, Santiago, Chile (Chile); Pozo, J. [Facultad de Ciencias de la Ingenieria. Universidad Diego Portales. Casilla 298-V, Santiago, Chile (Chile)

    1998-12-01

    The well-resolved emission and absorption spectra of centrosymmetric coordination compounds of the transition metal ions have been used widely to provide the experimental data against which to test theoretical models of vibronic intensities. With reference to the {sup 2} E{sub g} {yields} {sup 4} A{sub 2g} luminescence transition, at a perfect octahedral site in Cs{sub 2}SiF{sub 6}, over than one hundred vibronic lines are observed with line widths of a few wavenumber spread over some 3000 cm{sup -1}. This paper reports a through examination of both the electronic and vibrational factors, which influences the observed vibronic intensities of the various assigned and identified lines in the spectra of the MnF{sub 6} {sup 2-} complex ion in the Cs{sub 2}SiF{sub 6} cubic lattice. The origin and nature of higher order vibronic interactions are analysed on the basis of a symmetrized vibronic crystal field-ligand polarization model. (Author)

  10. The Utilization of Low Frequency Raman Spectra of Gases for the Study of Molecules with Large Amplitude Vibration

    Institute of Scientific and Technical Information of China (English)

    James R. Durig; Sarah Xiao-hua Zhou; Joshua Klaassen; Arindam Ganguly

    2009-01-01

    The utilization of the Raman spectra of the low frequency bending mode for three quasi-linear molecules, disiloxane, (SiH3)2 O; methylisocyanate, CH3NCO; and dimethy lisocyanate, (CH3)2SiHNCO for observing the low frequency anharmonic bending vibration is demonstrated which is superior to the corresponding far infrared spectra. From the observed frequencies from the Raman spectra the potential function governing the heavy atom motion to linearity has been obtained from which the barrier has been determined. These experimental values are compared to the ab ini-tio predicted values. Also low frequency Raman spectra of the ring puckering vibration of chlorocy-clobutane, c-C4H7Cl, bromocyclobutane, c-C4H7Br, and aminocyclobutane, c-C4H7NH2, have been utilized to obtain the potential function governing the ring inversion for these molecules. The deter-mined barriers to planarity are compared to those obtained from MP2 (full) ab initio and density functional theory B3LYP calculations by utilizing a variety of basis sets. For all of these studies it is shown that the Raman spectra are superior to the infrared spectra for determining the frequencies of the excited state transitions.

  11. Study of V-OTDR stability for dynamic strain measurement in piezoelectric vibration

    Science.gov (United States)

    Ren, Meiqi; Lu, Ping; Chen, Liang; Bao, Xiaoyi

    2016-09-01

    In a phase-sensitive optical-time domain reflectometry (Φ-OTDR) system, the challenge for dynamic strain measurement lies in large intensity fluctuations from trace to trace. The intensity fluctuation caused by stochastic characteristics of Rayleigh backscattering sets detection limit for the minimum strength of vibration measurement and causes the large measurement uncertainty. Thus, a trace-to-trace correlation coefficient is introduced to quantify intensity fluctuation of Φ-OTDR traces and stability of the sensor system theoretically and experimentally. A novel approach of measuring dynamic strain induced by various driving voltages of lead zirconate titanate (PZT) in Φ-OTDR is also demonstrated. Piezoelectric vibration signals are evaluated through analyzing peak values of fast Fourier transform spectra at the fundamental frequency and high-order harmonics based on Bessel functions. High trace-to-trace correlation coefficients varying from 0.824 to 0.967 among 100 measurements are obtained in experimental results, showing the good stability of our sensor system, as well as small uncertainty of measured peak values.

  12. Does hearing in response to soft-tissue stimulation involve skull vibrations? A within-subject comparison between skull vibration magnitudes and hearing thresholds.

    Science.gov (United States)

    Chordekar, Shai; Perez, Ronen; Adelman, Cahtia; Sohmer, Haim; Kishon-Rabin, Liat

    2018-04-03

    Hearing can be elicited in response to bone as well as soft-tissue stimulation. However, the underlying mechanism of soft-tissue stimulation is under debate. It has been hypothesized that if skull vibrations were the underlying mechanism of hearing in response to soft-tissue stimulation, then skull vibrations would be associated with hearing thresholds. However, if skull vibrations were not associated with hearing thresholds, an alternative mechanism is involved. In the present study, both skull vibrations and hearing thresholds were assessed in the same participants in response to bone (mastoid) and soft-tissue (neck) stimulation. The experimental group included five hearing-impaired adults in whom a bone-anchored hearing aid was implanted due to conductive or mixed hearing loss. Because the implant is exposed above the skin and has become an integral part of the temporal bone, vibration of the implant represented skull vibrations. To ensure that middle-ear pathologies of the experimental group did not affect overall results, hearing thresholds were also obtained in 10 participants with normal hearing in response to stimulation at the same sites. We found that the magnitude of the bone vibrations initiated by the stimulation at the two sites (neck and mastoid) detected by the laser Doppler vibrometer on the bone-anchored implant were linearly related to stimulus intensity. It was therefore possible to extrapolate the vibration magnitudes at low-intensity stimulation, where poor signal-to-noise ratio limited actual recordings. It was found that the vibration magnitude differences (between soft-tissue and bone stimulation) were not different than the hearing threshold differences at the tested frequencies. Results of the present study suggest that bone vibration magnitude differences can adequately explain hearing threshold differences and are likely to be responsible for the hearing sensation. Thus, the present results support the idea that bone and soft

  13. Low-frequency and wideband vibration energy harvester with flexible frame and interdigital structure

    Energy Technology Data Exchange (ETDEWEB)

    Li, Pengwei, E-mail: lipengwei@tyut.edu.cn; Wang, Yanfen; Luo, Cuixian; Li, Gang; Hu, Jie; Zhang, Wendong [MicroNano System Research Center of College of Information Engineering and Key Lab of Advanced Transducers and Intelligent Control System of the Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Liu, Ying [MicroNano System Research Center of College of Information Engineering and Key Lab of Advanced Transducers and Intelligent Control System of the Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, Shanxi (China); Baicheng Ordnance Test Center of China, Baicheng 137000, Jilin (China); Liu, Wei [Baicheng Ordnance Test Center of China, Baicheng 137000, Jilin (China)

    2015-04-15

    As an alternative to traditional cantilever beam structures and their evolutions, a flexible beam based, interdigital structure, vibration energy harvester has been presented and investigated. The proposed interdigital-shaped oscillator consists of a rectangular flexible frame and series of cantilever beams interdigitally bonded to it. In order to achieve low frequency and wide-bandwidth harvesting, Young’s modulus of materials, frame size and the amount of the cantilevers have been studied systematically. The measured frequency responses of the designed device (PDMS frame, quintuple piezoelectric cantilever beams) show a 460% increase in bandwidth below 80Hz. When excited at an acceleration of 1.0 g, the energy harvester achieves to a maximum open-circuit voltage of 65V, and the maximum output power 4.5 mW.

  14. Vortex-induced vibrations of circular cylinder in cross flow at supercritical Reynolds numbers; Chorinkai Reynolds su ryoiki ni okeru enchu no uzu reiki shindo

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, T.; Nakao, T.; Takahashi, M.; Hayashi, M.; Goto, N. [Hitachi, Ltd., Tokyo (Japan)

    1999-07-25

    Vortex-induced vibrations were measured for a circular cylinder subjected to a water cross flow at supercritical Reynolds numbers for a wide range of reduced velocities. Turbulence intensities were changed from 1% to 13% in order to investigate the effect of the Strouhal number on the region of synchronization by symmetrical and Karman vortex shedding. The reduced damping of the test cylinder was about 0.1 in water. The surface roughness of the cylinder was a mirror-polished surface. Strouhal number decreased from about 0.48 to 0.29 with increasing turbulence intensity. Synchronized vibrations were observed even at supercritical Reynolds numbers where fluctuating fluid force was small. Reduced velocities at which drag and lift direction lock-in by Karman vortex shedding were initiated decreased with increasing Strouhal number. When Strouhal number was about 0.29, the self-excited vibration in drag direction by symmetrical vortex shedding began at which the frequency ratio of Karman vortex shedding frequency to the natural frequency of cylinder was 0.32. (author)

  15. Interpreting intensities in vibrational sum frequency generation (SFG) spectroscopy: CO adsorption on Pd surfaces

    Science.gov (United States)

    Morkel, M.; Unterhalt, H.; Klüner, T.; Rupprechter, G.; Freund, H.-J.

    2005-07-01

    The lineshape and intensity of SFG signals of CO adsorbed on supported Pd nanoparticles and Pd(1 1 1) are analyzed. For CO/Pd(1 1 1) nearly symmetric lorentzian lineshapes were observed. Applying two different visible wavelengths for excitation, asymmetric lineshapes observed for the CO/Pd/Al 2O 3/NiAl(1 1 0) system are explained by a lower resonant and a higher non-resonant SFG signal and a change in the phase between resonant and non-resonant signals, most likely originating from an interband transition in the NiAl substrate. The relative intensity of different CO species (hollow, bridge, on-top) was modeled by DFT calculations of IR transition moments and Raman activities. While the (experimental) sensitivity of SFG towards different CO species strongly varies, the calculated IR and Raman activities are rather similar. The inability to exactly reproduce experimental SFG intensities suggests a strong coverage dependence of Raman activities or that non-linear effects occur that can currently not be properly accounted for.

  16. Some developments in core-barrel vibration diagnostics

    International Nuclear Information System (INIS)

    Pazsit, I.; Karlsson, J.; Garis, N.S.

    1998-01-01

    Diagnostics of core-barrel motion, and notably that of beam mode vibrations, has been usually performed by two distinct concepts. One strategy is to perform a qualitative analysis in the time domain, using descriptors such as vibration trajectory, probability distributions etc. This approach is rather realistic in the sense that it allows for general anisotropic pendular vibrations. The other strategy is to use frequency analysis with the goal of quantifying certain vibration properties. However, this second approach could so far handle only isotropic and unidirectional vibrations. In this paper we propose a unification of these two approaches by introducing a model by which general anisotropic vibrations can be quantified in the frequency domain. However, when separating the noise components prior to the frequency analysis, we suggest the use of symmetry properties of the noise in the time domain, based on reactor physics assumptions, as opposed to the earlier methods that use statistical independence of the components. Due to the unified approach, a combination of time and frequency domain analysis methods can be used for presentation and maximum information extraction

  17. Electronic and vibrational spectroscopy and vibrationally mediated photodissociation of V+(OCO).

    Science.gov (United States)

    Citir, Murat; Altinay, Gokhan; Metz, Ricardo B

    2006-04-20

    Electronic spectra of gas-phase V+(OCO) are measured in the near-infrared from 6050 to 7420 cm(-1) and in the visible from 15,500 to 16,560 cm(-1), using photofragment spectroscopy. The near-IR band is complex, with a 107 cm(-1) progression in the metal-ligand stretch. The visible band shows clearly resolved vibrational progressions in the metal-ligand stretch and rock, and in the OCO bend, as observed by Brucat and co-workers. A vibrational hot band gives the metal-ligand stretch frequency in the ground electronic state nu3'' = 210 cm(-1). The OCO antisymmetric stretch frequency in the ground electronic state (nu1'') is measured by using vibrationally mediated photodissociation. An IR laser vibrationally excites ions to nu1'' = 1. Vibrationally excited ions selectively dissociate following absorption of a second, visible photon at the nu1' = 1 CO2, due to interaction with the metal. Larger blue shifts observed for complexes with fewer ligands agree with trends seen for larger V+(OCO)n clusters.

  18. Multi-layer Lanczos iteration approach to calculations of vibrational energies and dipole transition intensities for polyatomic molecules

    International Nuclear Information System (INIS)

    Yu, Hua-Gen

    2015-01-01

    We report a rigorous full dimensional quantum dynamics algorithm, the multi-layer Lanczos method, for computing vibrational energies and dipole transition intensities of polyatomic molecules without any dynamics approximation. The multi-layer Lanczos method is developed by using a few advanced techniques including the guided spectral transform Lanczos method, multi-layer Lanczos iteration approach, recursive residue generation method, and dipole-wavefunction contraction. The quantum molecular Hamiltonian at the total angular momentum J = 0 is represented in a set of orthogonal polyspherical coordinates so that the large amplitude motions of vibrations are naturally described. In particular, the algorithm is general and problem-independent. An application is illustrated by calculating the infrared vibrational dipole transition spectrum of CH based on the ab initio T8 potential energy surface of Schwenke and Partridge and the low-order truncated ab initio dipole moment surfaces of Yurchenko and co-workers. A comparison with experiments is made. The algorithm is also applicable for Raman polarizability active spectra

  19. Intensity autocorrelation measurements of frequency combs in the terahertz range

    Science.gov (United States)

    Benea-Chelmus, Ileana-Cristina; Rösch, Markus; Scalari, Giacomo; Beck, Mattias; Faist, Jérôme

    2017-09-01

    We report on direct measurements of the emission character of quantum cascade laser based frequency combs, using intensity autocorrelation. Our implementation is based on fast electro-optic sampling, with a detection spectral bandwidth matching the emission bandwidth of the comb laser, around 2.5 THz. We find the output of these frequency combs to be continuous even in the locked regime, but accompanied by a strong intensity modulation. Moreover, with our record temporal resolution of only few hundreds of femtoseconds, we can resolve correlated intensity modulation occurring on time scales as short as the gain recovery time, about 4 ps. By direct comparison with pulsed terahertz light originating from a photoconductive emitter, we demonstrate the peculiar emission pattern of these lasers. The measurement technique is self-referenced and ultrafast, and requires no reconstruction. It will be of significant importance in future measurements of ultrashort pulses from quantum cascade lasers.

  20. Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration

    Science.gov (United States)

    Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.

    2016-01-01

    BACKGROUND Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined. OBJECTIVE The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools. METHODS A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations. RESULTS When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it. CONCLUSIONS This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for

  1. Prospects of Using High-Intensity THz Pulses To Induce Ultrafast Temperature-Jumps in Liquid Water.

    Science.gov (United States)

    Mishra, Pankaj Kr; Bettaque, Vincent; Vendrell, Oriol; Santra, Robin; Welsch, Ralph

    2018-06-01

    Ultrashort, high-intensity terahertz (THz) pulses, e.g., generated at free-electron laser facilities, allow for direct investigation as well as the driving of intermolecular modes in liquids like water and thus will deepen our understanding of the hydrogen bonding network. In this work, the temperature-jump (T-jump) of water induced by THz radiation is simulated for ten different THz frequencies in the range from 3 to 30 THz and five different pulse intensities in the range from 1 × 10 11 to 5 × 10 12 W/cm 2 employing both ab initio molecular dynamics (AIMD) and force field molecular dynamics (FFMD) approaches. The most efficient T-jump can be achieved with 16 THz pulses. Three distinct T-jump mechanisms can be uncovered. For all cases, the T-jump mechanism proceeds within tens of femtoseconds (fs). For frequencies between 10 and 25 THz, most of the energy is initially transferred to the rotational degrees of freedom. Subsequently, the energy is redistributed to the translational and intramolecular vibrational degrees of freedom within a maximum of 500 fs. For the lowest frequencies considered (7 THz and below), translational and rotational degrees of freedom are heated within tens of fs as the THz pulse also couples to the intermolecular vibrations. Subsequently, the intramolecular vibrational modes are heated within a few hundred fs. At the highest frequencies considered (25 THz and above), vibrational and rotational degrees of freedom are heated within tens of fs, and energy redistribution to the translational degrees of freedom happens within several hundred fs. Both AIMD and FFMD simulations show a similar dependence of the T-jump on the frequency employed. However, the FFMD simulations overestimate the total energy transfer around the main peak and drop off too fast toward frequencies higher and lower than the main peak. These differences can be rationalized by missing elements, such as the polarizability, in the TIP4P/2005f force field employed. The

  2. Two-dimensional vibrational-electronic spectroscopy

    Science.gov (United States)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira

    2015-10-01

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (νCN) and either a ligand-to-metal charge transfer transition ([FeIII(CN)6]3- dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN)5FeIICNRuIII(NH3)5]- dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific νCN modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a wide range of complex molecular, material, and biological systems.

  3. Two-dimensional vibrational-electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Courtney, Trevor L.; Fox, Zachary W.; Slenkamp, Karla M.; Khalil, Munira, E-mail: mkhalil@uw.edu [Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195 (United States)

    2015-10-21

    Two-dimensional vibrational-electronic (2D VE) spectroscopy is a femtosecond Fourier transform (FT) third-order nonlinear technique that creates a link between existing 2D FT spectroscopies in the vibrational and electronic regions of the spectrum. 2D VE spectroscopy enables a direct measurement of infrared (IR) and electronic dipole moment cross terms by utilizing mid-IR pump and optical probe fields that are resonant with vibrational and electronic transitions, respectively, in a sample of interest. We detail this newly developed 2D VE spectroscopy experiment and outline the information contained in a 2D VE spectrum. We then use this technique and its single-pump counterpart (1D VE) to probe the vibrational-electronic couplings between high frequency cyanide stretching vibrations (ν{sub CN}) and either a ligand-to-metal charge transfer transition ([Fe{sup III}(CN){sub 6}]{sup 3−} dissolved in formamide) or a metal-to-metal charge transfer (MMCT) transition ([(CN){sub 5}Fe{sup II}CNRu{sup III}(NH{sub 3}){sub 5}]{sup −} dissolved in formamide). The 2D VE spectra of both molecules reveal peaks resulting from coupled high- and low-frequency vibrational modes to the charge transfer transition. The time-evolving amplitudes and positions of the peaks in the 2D VE spectra report on coherent and incoherent vibrational energy transfer dynamics among the coupled vibrational modes and the charge transfer transition. The selectivity of 2D VE spectroscopy to vibronic processes is evidenced from the selective coupling of specific ν{sub CN} modes to the MMCT transition in the mixed valence complex. The lineshapes in 2D VE spectra report on the correlation of the frequency fluctuations between the coupled vibrational and electronic frequencies in the mixed valence complex which has a time scale of 1 ps. The details and results of this study confirm the versatility of 2D VE spectroscopy and its applicability to probe how vibrations modulate charge and energy transfer in a

  4. Impact of acoustic airflow on intrasinus drug deposition: New insights into the vibrating mode and the optimal acoustic frequency to enhance the delivery of nebulized antibiotic.

    Science.gov (United States)

    Leclerc, Lara; Merhie, Amira El; Navarro, Laurent; Prévôt, Nathalie; Durand, Marc; Pourchez, Jérémie

    2015-10-15

    We investigated the impact of vibrating acoustic airflow, the high frequency (f≥100 Hz) and the low frequency (f≤45 Hz) sound waves, on the enhancement of intrasinus drug deposition. (81m)Kr-gas ventilation study was performed in a plastinated human cast with and without the addition of vibrating acoustic airflow. Similarly, intrasinus drug deposition in a nasal replica using gentamicin as a marker was studied with and without the superposition of different modes of acoustic airflow. Ventilation experiments demonstrate that no sinus ventilation was observed without acoustic airflow although sinus ventilation occurred whatever the modes of acoustic airflow applied. Intrasinus drug deposition experiments showed that the high frequency acoustic airflow led to 4-fold increase in gentamicin deposition into the left maxillary sinus and to 2-fold deposition increase into the right maxillary sinus. Besides, the low frequency acoustic airflow demonstrated a significant increase of 4-fold and 2-fold in the right and left maxillary sinuses, respectively. We demonstrated the benefit of different modes of vibrating acoustic airflow for maxillary sinus ventilation and intrasinus drug deposition. The degree of gentamicin deposition varies as a function of frequency of the vibrating acoustic airflow and the geometry of the ostia. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Adaptive Piezoelectric Absorber for Active Vibration Control

    Directory of Open Access Journals (Sweden)

    Sven Herold

    2016-02-01

    Full Text Available Passive vibration control solutions are often limited to working reliably at one design point. Especially applied to lightweight structures, which tend to have unwanted vibration, active vibration control approaches can outperform passive solutions. To generate dynamic forces in a narrow frequency band, passive single-degree-of-freedom oscillators are frequently used as vibration absorbers and neutralizers. In order to respond to changes in system properties and/or the frequency of excitation forces, in this work, adaptive vibration compensation by a tunable piezoelectric vibration absorber is investigated. A special design containing piezoelectric stack actuators is used to cover a large tuning range for the natural frequency of the adaptive vibration absorber, while also the utilization as an active dynamic inertial mass actuator for active control concepts is possible, which can help to implement a broadband vibration control system. An analytical model is set up to derive general design rules for the system. An absorber prototype is set up and validated experimentally for both use cases of an adaptive vibration absorber and inertial mass actuator. Finally, the adaptive vibration control system is installed and tested with a basic truss structure in the laboratory, using both the possibility to adjust the properties of the absorber and active control.

  6. Coherent optical effect on time-resolved vibrational SFG spectrum of adsorbates

    Science.gov (United States)

    Ueba, H.; Sawabu, T.; Mii, T.

    2002-04-01

    We present a theory to study the influence of the coherent mixing between pump-infrared and probe-visible pulse on a time-resolved sum-frequency generation (TR-SFG) spectrum for vibrations at surfaces. The general formula of the time-dependent and its Fourier transform of the SFG polarization and its Fourier transform allows us to calculate the time-resolved vibrational SFG spectrum and the transient characteristics of the SFG intensity as a function of the delay time td between the pump-infrared and probe-visible pulse. It is found the coherent optical effect manifests itself in the broadening and narrowing of the SFG spectrum with the intrinsic width of T2 at negative and positive td, respectively, being in qualitative agreement with recent experimental results. The influence of the coherent mixing on the transient behavior of the SFG intensity is also discussed in conjunction to the T2 determination.

  7. MR Damper Controlled Vibration Absorber for Enhanced Mitigation of Harmonic Vibrations

    Directory of Open Access Journals (Sweden)

    Felix Weber

    2016-12-01

    Full Text Available This paper describes a semi-active vibration absorber (SVA concept based on a real-time controlled magnetorheological damper (MR-SVA for the enhanced mitigation of structural vibrations due to harmonic disturbing forces. The force of the MR damper is controlled in real-time to generate the frequency and damping controls according to the behaviour of the undamped vibration absorber for the actual frequency of vibration. As stiffness and damping emulations in semi-active actuators are coupled quantities the control is formulated to prioritize the frequency control by the controlled stiffness. The control algorithm is augmented by a stiffness correction method ensuring precise frequency control when the desired control force is constrained by the semi-active restriction and residual force of the MR damper. The force tracking task is solved by a model-based feed forward with feedback correction. The MR-SVA is numerically and experimentally validated for the primary structure with nominal eigenfrequency and when de-tuning of −10%, −5%, +5% and +10% is present. Both validations demonstrate that the MR-SVA improves the vibration reduction in the primary structure by up to 55% compared to the passive tuned mass damper (TMD. Furthermore, it is shown that the MR-SVA with only 80% of tuned mass leads to approximately the same enhanced performance while the associated increased relative motion amplitude of the tuned mass is more than compensated be the reduced dimensions of the mass. Therefore, the MR-SVA is an appropriate solution for the mitigation of tall buildings where the pendulum mass can be up to several thousands of metric tonnes and space for the pendulum damper is limited.

  8. Surprising Performance for Vibrational Frequencies of the Distinguishable Clusters with Singles and Doubles (DCSD) and MP2.5 Approximations

    OpenAIRE

    Kesharwani, Manoj K.; Sylvetsky, Nitai; Martin, Jan M. L.

    2017-01-01

    We show that the DCSD (distinguishable clusters with all singles and doubles) correlation method permits the calculation of vibrational spectra at near-CCSD(T) quality but at no more than CCSD cost, and with comparatively inexpensive analytical gradients. For systems dominated by a single reference configuration, even MP2.5 is a viable alternative, at MP3 cost. MP2.5 performance for vibrational frequencies is comparable to double hybrids such as DSD-PBEP86-D3BJ, but without resorting to empir...

  9. Cleaning device for vibrational hose filter

    Energy Technology Data Exchange (ETDEWEB)

    Engels, R

    1978-01-05

    Filter hoses out of web in dust separators can be cleaned by enforced vibrations. The efficiency of the cleaning is a maximum if the vibrations are at about the individual frequency of the whole arrangement. In the interior of the hose a cage from bars parallel to the wall of the hose is placed on its total length. The bars are fixed at one end and connected with a vibration exciter at the other end. The unilaterally fixed vibration bars can be adjusted to the individual frequency of the vibration exciter. If the hose filter is flown through from the outer to the inner side the vibration bars serve as a supporting body. In the reverse case the bars are placed on the outer side of the hose filter.

  10. Low-frequency and wideband vibration energy harvester with flexible frame and interdigital structure

    Directory of Open Access Journals (Sweden)

    Pengwei Li

    2015-04-01

    Full Text Available As an alternative to traditional cantilever beam structures and their evolutions, a flexible beam based, interdigital structure, vibration energy harvester has been presented and investigated. The proposed interdigital-shaped oscillator consists of a rectangular flexible frame and series of cantilever beams interdigitally bonded to it. In order to achieve low frequency and wide-bandwidth harvesting, Young’s modulus of materials, frame size and the amount of the cantilevers have been studied systematically. The measured frequency responses of the designed device (PDMS frame, quintuple piezoelectric cantilever beams show a 460% increase in bandwidth below 80Hz. When excited at an acceleration of 1.0 g, the energy harvester achieves to a maximum open-circuit voltage of 65V, and the maximum output power 4.5 mW.

  11. Natural frequency and vibration analysis of jacket type foundation for offshore wind power

    Science.gov (United States)

    Hung, Y.-C.; Chang, Y.-Y.; Chen, S.-Y.

    2017-12-01

    There are various types of foundation structure for offshore wind power, engineers may assess the condition of ocean at wind farm, and arrange the transportation, installation of each structure members, furthermore, considering the ability of manufacture steel structure as well, then make an optimum design. To design jacket offshore structure, unlike onshore cases, offshore structure also need to estimate the wave excitation effect. The aim of this paper is to study the difference of natural frequency between different kinds of structural stiffness and discuss the effect of different setting of boundary condition during analysis, besides, compare this value with the natural frequency of sea wave, in order to avoid the resonance effect. In this paper, the finite element analysis software ABAQUS is used to model and analyze the natural vibration behavior of the jacket structure.

  12. High-pressure Raman study of vibrational spectra in crystalline acetanilide

    Science.gov (United States)

    Sakai, Masamichi; Kuroda, Noritaka; Nishina, Yuichiro

    1993-01-01

    We have studied the effect of pressure on the low-frequency lattice modes and the amide-I (N-CO stretching) vibrational modes in crystalline acetanilide (C6H5NHCOCH3) in the temperature range 80-300 K by means of Raman spectroscopy. The Raman intensity of the 1650-cm-1 band, which appears upon cooling, is enhanced by applying pressure. The energy difference between the amide-I phonon (Ag mode) and the 1650-cm-1 bands does not change appreciably under pressure up to at least 4 GPa. These results are analyzed in terms of the self-trapped model in which a single lattice mode couples with the amide-I excitation by taking into account the effect of pressure on the low-frequency lattice modes and on the dipole-dipole interactions associated with the amide-I vibration. A band is observed at 30 cm-1 below the amide-I phonon band at low temperatures with a pressure above ~2 GPa.

  13. Urban vibrations

    DEFF Research Database (Denmark)

    Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen

    2012-01-01

    In   this   paper   we   describe   a   field   study   conducted   with   a   wearable   vibration   belt   where   we   test   to   determine   the   vibration   intensity   sensitivity   ranges   on   a   large   diverse   group   of   participants   with   evenly   distributed  ages  and...

  14. Analysis of bifurcation behavior of a piecewise linear vibrator with electromagnetic coupling for energy harvesting applications

    KAUST Repository

    El Aroudi, Abdelali

    2014-05-01

    Recently, nonlinearities have been shown to play an important role in increasing the extracted energy of vibration-based energy harvesting systems. In this paper, we study the dynamical behavior of a piecewise linear (PWL) spring-mass-damper system for vibration-based energy harvesting applications. First, we present a continuous time single degree of freedom PWL dynamical model of the system. Different configurations of the PWL model and their corresponding state-space regions are derived. Then, from this PWL model, extensive numerical simulations are carried out by computing time-domain waveforms, state-space trajectories and frequency responses under a deterministic harmonic excitation for different sets of system parameter values. Stability analysis is performed using Floquet theory combined with Filippov method, Poincaré map modeling and finite difference method (FDM). The Floquet multipliers are calculated using these three approaches and a good concordance is obtained among them. The performance of the system in terms of the harvested energy is studied by considering both purely harmonic excitation and a noisy vibrational source. A frequency-domain analysis shows that the harvested energy could be larger at low frequencies as compared to an equivalent linear system, in particular, for relatively low excitation intensities. This could be an advantage for potential use of this system in low frequency ambient vibrational-based energy harvesting applications. © 2014 World Scientific Publishing Company.

  15. Axisymmetric vibrations of thick shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    Axisymmetric shells of revolution are used for chemical plants, nuclear power plants, aircrafts, structures and so on, and the elucidation of their free vibration is important for the design. In this study, the axisymmetric vibration of a barrel-shaped shell was analyzed by the modified thick shell theory. The Lagrangian during one period of the vibration of a shell of revolution was determined, and from its stopping condition, the vibration equations and the boundary conditions were derived. The vibration equations were analyzed strictly by using the series solution. Moreover, the basic equations for the strain of a shell and others were based on those of Love. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. By comparing the results of this study with the results by thin shell theory, the effects of shearing deformation and rotary inertia on the natural frequency and vibration mode were clarified. The theoretical analysis and the numerical calculation are described. The effects of shearing deformation and rotary inertia on the natural frequency became larger in the higher order vibration. The vibration mode did not much change in both theories. (Kako, I.)

  16. Two-dimensional concentrated-stress low-frequency piezoelectric vibration energy harvesters

    Energy Technology Data Exchange (ETDEWEB)

    Sharpes, Nathan [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Abdelkefi, Abdessattar [Department of Mechanical and Aerospace Engineering, New Mexico State University, Las Cruces, New Mexico 88003 (United States); Priya, Shashank [Center for Energy Harvesting Materials and Systems (CEHMS), Virginia Tech, Blacksburg, Virginia 24061 (United States); Bio-Inspired Materials and Devices Laboratory (BMDL), Virginia Tech, Blacksburg, Virginia 24061 (United States)

    2015-08-31

    Vibration-based energy harvesters using piezoelectric materials have long made use of the cantilever beam structure. Surmounting the deficiencies in one-dimensional cantilever-based energy harvesters has been a major focus in the literature. In this work, we demonstrate a strategy of using two-dimensional beam shapes to harvest energy from low frequency excitations. A characteristic Zigzag-shaped beam is created to compare against the two proposed two-dimensional beam shapes, all of which occupy a 25.4 × 25.4 mm{sup 2} area. In addition to maintaining the low-resonance bending frequency, the proposed beam shapes are designed with the goal of realizing a concentrated stress structure, whereby stress in the beam is concentrated in a single area where a piezoelectric layer may be placed, rather than being distributed throughout the beam. It is shown analytically, numerically, and experimentally that one of the proposed harvesters is able to provide significant increase in power production, when the base acceleration is set equal to 0.1 g, with only a minimal change in the resonant frequency compared to the current state-of-the-art Zigzag shape. This is accomplished by eliminating torsional effects, producing a more pure bending motion that is necessary for high electromechanical coupling. In addition, the proposed harvesters have a large effective beam tip whereby large tip mass may be placed while retaining a low-profile, resulting in a low volume harvester and subsequently large power density.

  17. Ab initio anharmonic vibrational frequency predictions for linear proton-bound complexes OC-H(+)-CO and N(2)-H(+)-N(2).

    Science.gov (United States)

    Terrill, Kasia; Nesbitt, David J

    2010-08-01

    Ab initio anharmonic transition frequencies are calculated for strongly coupled (i) asymmetric and (ii) symmetric proton stretching modes in the X-H(+)-X linear ionic hydrogen bonded complexes for OCHCO(+) and N(2)HN(2)(+). The optimized potential surface is calculated in these two coordinates for each molecular ion at CCSD(T)/aug-cc-pVnZ (n = 2-4) levels and extrapolated to the complete-basis-set limit (CBS). Slices through both 2D surfaces reveal a relatively soft potential in the asymmetric proton stretching coordinate at near equilibrium geometries, which rapidly becomes a double minimum potential with increasing symmetric proton acceptor center of mass separation. Eigenvalues are obtained by solution of the 2D Schrödinger equation with potential/kinetic energy coupling explicity taken into account, converged in a distributed Gaussian basis set as a function of grid density. The asymmetric proton stretch fundamental frequency for N(2)HN(2)(+) is predicted at 848 cm(-1), with strong negative anharmonicity in the progression characteristic of a shallow "particle in a box" potential. The corresponding proton stretch fundamental for OCHCO(+) is anomalously low at 386 cm(-1), but with a strong alternation in the vibrational spacing due to the presence of a shallow D(infinityh) transition state barrier (Delta = 398 cm(-1)) between the two equivalent minimum geometries. Calculation of a 2D dipole moment surface and transition matrix elements reveals surprisingly strong combination and difference bands with appreciable intensity throughout the 300-1500 cm(-1) region. Corrected for zero point (DeltaZPE) and thermal vibrational excitation (DeltaE(vib)) at 300 K, the single and double dissociation energies in these complexes are in excellent agreement with thermochemical gas phase ion data.

  18. Flow-induced vibration of helical coil compression springs

    International Nuclear Information System (INIS)

    Stokes, F.E.; King, R.A.

    1983-01-01

    Helical coil compression springs are used in some nuclear fuel assembly designs to maintain holddown and to accommodate thermal expansion. In the reactor environment, the springs are exposed to flowing water, elevated temperatures and pressures, and irradiation. Flow parallel to the longitudinal axis of the spring may excite the spring coils and cause vibration. The purpose of this investigation was to determine the flow-induced vibration (FIV) response characteristics of the helical coil compression springs. Experimental tests indicate that a helical coil spring responds like a single circular cylinder in cross-flow. Two FIV excitation mechanisms control spring vibration. Namely: 1) Turbulent Buffeting causes small amplitude vibration which increases as a function of velocity squared. 2) Vortex Shedding causes large amplitude vibration when the spring natural frequency and Strouhal frequency coincide. Several methods can be used to reduce or to prevent vortex shedding large amplitude vibrations. One method is compressing the spring to a coil pitch-to-diameter ratio of 2 thereby suppressing the vibration amplitude. Another involves modifying the spring geometry to alter its stiffness and frequency characteristics. These changes result in separation of the natural and Strouhal frequencies. With an understanding of how springs respond in the flowing water environment, the spring physical parameters can be designed to avoid large amplitude vibration. (orig.)

  19. The Relation between Frequency of E-Cigarette Use and Frequency and Intensity of Cigarette Smoking among South Korean Adolescents.

    Science.gov (United States)

    Lee, Jung Ah; Lee, Sungkyu; Cho, Hong-Jun

    2017-03-14

    The prevalence of adolescent electronic cigarette (e-cigarette) use has increased in most countries. This study aims to determine the relation between the frequency of e-cigarette use and the frequency and intensity of cigarette smoking. Additionally, the study evaluates the association between the reasons for e-cigarette use and the frequency of its use. Using the 2015 Korean Youth Risk Behavior Web-Based Survey, we included 6655 adolescents with an experience of e-cigarette use who were middle and high school students aged 13-18 years. We compared smoking experience, the frequency and intensity of cigarette smoking, and the relation between the reasons for e-cigarette uses and the frequency of e-cigarette use. The prevalence of e-cigarette ever and current (past 30 days) users were 10.1% and 3.9%, respectively. Of the ever users, approximately 60% used e-cigarettes not within 1 month. On the other hand, 8.1% used e-cigarettes daily. The frequent and intensive cigarette smoking was associated with frequent e-cigarette uses. The percentage of frequent e-cigarette users (≥10 days/month) was 3.5% in adolescents who did not smoke within a month, but 28.7% among daily smokers. Additionally, it was 9.1% in smokers who smoked less than 1 cigarette/month, but 55.1% in smokers who smoked ≥20 cigarettes/day. The most common reason for e-cigarette use was curiosity (22.9%), followed by the belief that they are less harmful than conventional cigarettes (18.9%), the desire to quit smoking (13.1%), and the capacity for indoor use (10.7%). Curiosity was the most common reason among less frequent e-cigarette users; however, the desire to quit smoking and the capacity for indoor use were the most common reasons among more frequent users. Results showed a positive relation between frequency or intensity of conventional cigarette smoking and the frequency of e-cigarette use among Korean adolescents, and frequency of e-cigarette use differed according to the reason for the use of

  20. Vertical vibration and shape oscillation of acoustically levitated water drops

    International Nuclear Information System (INIS)

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

    2014-01-01

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  1. Vertical vibration and shape oscillation of acoustically levitated water drops

    Energy Technology Data Exchange (ETDEWEB)

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B., E-mail: bbwei@nwpu.edu.cn [Department of Applied Physics, Northwestern Polytechnical University, Xi' an 710072 (China)

    2014-09-08

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  2. Vibration-proof FBR type reactor

    International Nuclear Information System (INIS)

    Kawamura, Yutaka.

    1992-01-01

    In a reactor container in an FBR type reactor, an outer building and upper and lower portions of a reactor container are connected by a load transmission device made of a laminated material of rubber and steel plates. Each of the reactor container and the outer building is disposed on a lower raft disposed on a rock by way of a vibration-proof device made of a laminated material of rubber and steel plates. Vibration-proof elements for providing vertical eigen frequency of the vibration-proof system comprising the reactor building and the vibration-proof device within a range of 3Hz to 5Hz are used. That is, the peak of designed acceleration for response spectrum in the horizontal direction of the reactor structural portions is shifted to side of shorter period from the main frequency region of the reactor structure. Alternatively, rigidity of the vibration-proof elements is decreased to shift the peak to the side of long period from the main frequency region. Designed seismic force can be greatly reduced both horizontally and vertically, to reduce the wall thickness of the structural members, improve the plant economy and to ensure the safety against earthquakes. (N.H.)

  3. Geometrical nonlinear free vibration of multi-layered graphene sheets

    International Nuclear Information System (INIS)

    Wang Jinbao; He Xiaoqiao; Kitipornchai, S; Zhang Hongwu

    2011-01-01

    A nonlinear continuum model is developed for the nonlinear vibration analysis of multi-layered graphene sheets (MLGSs), in which the nonlinear van der Waals (vdW) interaction between any two layers is formulated explicitly. The nonlinear equations of motion are studied by the harmonic-balance methods. Based on the present model, the nonlinear stiffened amplitude-frequency relations of double-layered graphene sheets (DLGSs) are investigated in the spectral neighbourhood of lower frequencies. The influence of the vdW interaction on the vibration properties of DLGSs is well illustrated by plotting the resulting modes' shapes, in which in-phase and anti-phase vibrations of DLGSs are studied. In particular, the large-amplitude vibration which associates with the anti-phase resonant frequencies, separating DLGS into single-layered GSs, is a promising application that needs to be explored further. In contrast, the vibration modes that are associated with the resonant frequencies are nonidentical and give various vibration patterns, which indicates that MLGSs are highly suited to being used as high-frequency resonators.

  4. Adaptive learning algorithms for vibration energy harvesting

    International Nuclear Information System (INIS)

    Ward, John K; Behrens, Sam

    2008-01-01

    By scavenging energy from their local environment, portable electronic devices such as MEMS devices, mobile phones, radios and wireless sensors can achieve greater run times with potentially lower weight. Vibration energy harvesting is one such approach where energy from parasitic vibrations can be converted into electrical energy through the use of piezoelectric and electromagnetic transducers. Parasitic vibrations come from a range of sources such as human movement, wind, seismic forces and traffic. Existing approaches to vibration energy harvesting typically utilize a rectifier circuit, which is tuned to the resonant frequency of the harvesting structure and the dominant frequency of vibration. We have developed a novel approach to vibration energy harvesting, including adaptation to non-periodic vibrations so as to extract the maximum amount of vibration energy available. Experimental results of an experimental apparatus using an off-the-shelf transducer (i.e. speaker coil) show mechanical vibration to electrical energy conversion efficiencies of 27–34%

  5. Formation of hypereutectic silicon particles in hypoeutectic Al-Si alloys under the influence of high-intensity ultrasonic vibration

    Directory of Open Access Journals (Sweden)

    Xiaogang Jian

    2013-03-01

    Full Text Available The modification of eutectic silicon is of general interest since fine eutectic silicon along with fine primary aluminum grains improves mechanical properties and ductilities. In this study, high intensity ultrasonic vibration was used to modify the complex microstructure of aluminum hypoeutectic alloys. The ultrasonic vibrator was placed at the bottom of a copper mold with molten aluminum. Hypoeutectic Al-Si alloy specimens with a unique in-depth profile of microstructure distribution were obtained. Polyhedral silicon particles, which should form in a hypereutectic alloy, were obtained in a hypoeutectic Al-Si alloy near the ultrasonic radiator where the silicon concentration was higher than the eutectic composition. The formation of hypereutectic silicon near the radiator surface indicates that high-intensity ultrasonic vibration can be used to influence the phase transformation process of metals and alloys. The size and morphology of both the silicon phase and the aluminum phase varies with increasing distance from the ultrasonic probe/radiator. Silicon morphology develops into three zones. Polyhedral primary silicon particles present in zone I, within 15 mm from the ultrasonic probe/radiator. Transition from hypereutectic silicon to eutectic silicon occurs in zone II about 15 to 20 祄 from the ultrasonic probe/radiator. The bulk of the ingot is in zone III and is hypoeutectic Al-Si alloy containing fine lamellar and fibrous eutectic silicon. The grain size is about 15 to 25 祄 in zone I, 25 to 35 祄 in zone II, and 25 to 55 祄 in zone III. The morphology of the primary ?Al phase is also changed from dendritic (in untreated samples to globular. Phase evolution during the solidification process of the alloy subjected to ultrasonic vibration is described.

  6. THE POSSIBLE INTERSTELLAR ANION CH{sub 2}CN{sup -}: SPECTROSCOPIC CONSTANTS, VIBRATIONAL FREQUENCIES, AND OTHER CONSIDERATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Fortenberry, Ryan C.; Lee, Timothy J. [NASA Ames Research Center, Moffett Field, CA 94035-1000 (United States); Crawford, T. Daniel, E-mail: Ryan.C.Fortenberry@nasa.gov, E-mail: Timothy.J.Lee@nasa.gov [Department of Chemistry, Virginia Tech, Blacksburg, VA 24061 (United States)

    2013-01-10

    The A {sup 1}B{sub 1} Leftwards-Open-Headed-Arrow X-tilde{sup 1}A' excitation into the dipole-bound state of the cyanomethyl anion (CH{sub 2}CN{sup -}) has been hypothesized as the carrier for one diffuse interstellar band. However, this particular molecular system has not been detected in the interstellar medium even though the related cyanomethyl radical and the isoelectronic ketenimine molecule have been found. In this study, we are employing the use of proven quartic force fields and second-order vibrational perturbation theory to compute accurate spectroscopic constants and fundamental vibrational frequencies for X-tilde{sup 1} A' CH{sub 2}CN{sup -} in order to assist in laboratory studies and astronomical observations.

  7. Parallel two-phase-flow-induced vibrations in fuel pin model

    International Nuclear Information System (INIS)

    Hara, Fumio; Yamashita, Tadashi

    1978-01-01

    This paper reports the experimental results of vibrations of a fuel pin model -herein meaning the essential form of a fuel pin from the standpoint of vibration- in a parallel air-and-water two-phase flow. The essential part of the experimental apparatus consisted of a flat elastic strip made of stainless steel, both ends of which were firmly supported in a circular channel conveying the two-phase fluid. Vibrational strain of the fuel pin model, pressure fluctuation of the two-phase flow and two-phase-flow void signals were measured. Statistical measures such as power spectral density, variance and correlation function were calculated. The authors obtained (1) the relation between variance of vibrational strain and two-phase-flow velocity, (2) the relation between variance of vibrational strain and two-phase-flow pressure fluctuation, (3) frequency characteristics of variance of vibrational strain against the dominant frequency of the two-phase-flow pressure fluctuation, and (4) frequency characteristics of variance of vibrational strain against the dominant frequency of two-phase-flow void signals. The authors conclude that there exist two kinds of excitation mechanisms in vibrations of a fuel pin model inserted in a parallel air-and-water two-phase flow; namely, (1) parametric excitation, which occurs when the fundamental natural frequency of the fuel pin model is related to the dominant travelling frequency of water slugs in the two-phase flow by the ratio 1/2, 1/1, 3/2 and so on; and (2) vibrational resonance, which occurs when the fundamental frequency coincides with the dominant frequency of the two-phase-flow pressure fluctuation. (auth.)

  8. Axisymmetric vibrations of thin shells of revolution

    International Nuclear Information System (INIS)

    Suzuki, Katsuyoshi; Kikuchi, Norio; Kosawada, Tadashi; Takahashi, Shin

    1983-01-01

    The problem of free vibration of axisymmetric shells of revolution is important in connection with the design of pressure vessels, chemical equipment, aircrafts, structures and so on. In this study, the axisymmetrical vibration of a thin shell of revolution having a constant curvature in meridian direction was analyzed by thin shell theory. First, the Lagrangian during one period of the vibration of a shell of revolution was determined by the primary approximate theory of Love, and the vibration equations and boundary conditions were derived from its stopping condition. The vibration equations were strictly analyzed by using the series solution. The basic equations for the strain and strain energy of a shell were based on those of Novozhilov. As the examples of numerical calculation, the natural frequency and vibration mode of the symmetrical shells of revolution fixed at both ends and supported at both ends were determined, and their characteristics were clarified. The theory and the numerical calculation ore described. Especially in the frequency curves, the waving phenomena were observed frequently, which were not seen in non-axisymmetric vibration, accordingly also the vibration mode changed in complex state on the frequency curves of same order. The numerical calculation was carried out in the large computer center in Tohoku University. (Kako, I.)

  9. Time-varying output performances of piezoelectric vibration energy harvesting under nonstationary random vibrations

    Science.gov (United States)

    Yoon, Heonjun; Kim, Miso; Park, Choon-Su; Youn, Byeng D.

    2018-01-01

    Piezoelectric vibration energy harvesting (PVEH) has received much attention as a potential solution that could ultimately realize self-powered wireless sensor networks. Since most ambient vibrations in nature are inherently random and nonstationary, the output performances of PVEH devices also randomly change with time. However, little attention has been paid to investigating the randomly time-varying electroelastic behaviors of PVEH systems both analytically and experimentally. The objective of this study is thus to make a step forward towards a deep understanding of the time-varying performances of PVEH devices under nonstationary random vibrations. Two typical cases of nonstationary random vibration signals are considered: (1) randomly-varying amplitude (amplitude modulation; AM) and (2) randomly-varying amplitude with randomly-varying instantaneous frequency (amplitude and frequency modulation; AM-FM). In both cases, this study pursues well-balanced correlations of analytical predictions and experimental observations to deduce the relationships between the time-varying output performances of the PVEH device and two primary input parameters, such as a central frequency and an external electrical resistance. We introduce three correlation metrics to quantitatively compare analytical prediction and experimental observation, including the normalized root mean square error, the correlation coefficient, and the weighted integrated factor. Analytical predictions are in an excellent agreement with experimental observations both mechanically and electrically. This study provides insightful guidelines for designing PVEH devices to reliably generate electric power under nonstationary random vibrations.

  10. Fin whale sound reception mechanisms: skull vibration enables low-frequency hearing.

    Directory of Open Access Journals (Sweden)

    Ted W Cranford

    Full Text Available Hearing mechanisms in baleen whales (Mysticeti are essentially unknown but their vocalization frequencies overlap with anthropogenic sound sources. Synthetic audiograms were generated for a fin whale by applying finite element modeling tools to X-ray computed tomography (CT scans. We CT scanned the head of a small fin whale (Balaenoptera physalus in a scanner designed for solid-fuel rocket motors. Our computer (finite element modeling toolkit allowed us to visualize what occurs when sounds interact with the anatomic geometry of the whale's head. Simulations reveal two mechanisms that excite both bony ear complexes, (1 the skull-vibration enabled bone conduction mechanism and (2 a pressure mechanism transmitted through soft tissues. Bone conduction is the predominant mechanism. The mass density of the bony ear complexes and their firmly embedded attachments to the skull are universal across the Mysticeti, suggesting that sound reception mechanisms are similar in all baleen whales. Interactions between incident sound waves and the skull cause deformations that induce motion in each bony ear complex, resulting in best hearing sensitivity for low-frequency sounds. This predominant low-frequency sensitivity has significant implications for assessing mysticete exposure levels to anthropogenic sounds. The din of man-made ocean noise has increased steadily over the past half century. Our results provide valuable data for U.S. regulatory agencies and concerned large-scale industrial users of the ocean environment. This study transforms our understanding of baleen whale hearing and provides a means to predict auditory sensitivity across a broad spectrum of sound frequencies.

  11. Heterogeneous Dynamics of Coupled Vibrations

    NARCIS (Netherlands)

    Cringus, Dan; Jansen, Thomas I. C.; Pshenichnikov, Maxim S.; Schoenlein, RW; Corkum, P; DeSilvestri, S; Nelson, KA; Riedle, E

    2009-01-01

    Frequency-dependent dynamics of coupled stretch vibrations of a water molecule are revealed by 2D IR correlation spectroscopy. These are caused by non-Gaussian fluctuations of the environment around the individual OH stretch vibrations.

  12. Fiber optic vibration sensor using bifurcated plastic optical fiber

    Science.gov (United States)

    Abdullah, M.; Bidin, N.; Yasin, M.

    2016-11-01

    An extrinsic fiber optic vibration sensor is demonstrated for a fiber optic displacement sensor based on a bundled multimode fiber to measure a vibration frequency ranging from 100 until 3000 Hz. The front slope has a sensitivity of 0.1938mV/mm and linearity of 99.7% within a measurement range between 0.15-3.00 mm. By placing the diaphragm of the concave load-speaker within the linear range from the probe, the frequency of the vibration can be measured with error percentage of less than 1.54%. The graph of input against output frequency for low, medium and high frequency range show very high linearity up to 99%. Slope for low, medium, and high frequency range are calculated as 1.0026, 0.9934, and 1.0007 respectively. Simplicity, long term stability, low power consumption, wide dynamic and frequency ranges, noise reduction, ruggedness, linearity and light weight make it promising alternative to other well-establish methods for vibration frequency measurement.

  13. Influence of intensity parameters of earthquake on response of reinforced concrete structures

    Science.gov (United States)

    Cherian, Ciby Jacob; Madhavan Pillai, T. M.; Sajith, A. S.

    2018-03-01

    Earthquake is one of the most frightening and destructive phenomena of nature. The destructive capacity of an earthquake depends on various parameters. Without characterising earthquake time history data to the required intensity parameters, its effect on structures cannot be predicted. The influence of intensity parameter of earthquake on the destructive capacity of a structure is essential in the vibration control scenario also. In the present paper, three reinforced concrete (RC) framed structures with natural frequencies 4.688 Hz, 1.762 Hz, 1.661 Hz are used to investigate the influence between the intensity measures and the response. 20 ground motion time history data were selected with predominant frequency ranging from 1 Hz to 12.5 Hz. Some available intensity measures were used to characterise this data. 3D model of the structure was analysed in ETABSUL 13.1.3 software with diaphragm rigidity at floor level. Modal analysis was used to find the modes and corresponding time periods. Linear time history analysis was done for the three models for all the ground motion data. It is noted that four intensity parameters namely predominant frequency, Peak Ground Acceleration, Velocity Spectrum Intensity, Housner Intensity has an appreciable influence on the response.

  14. The Relation between Frequency of E-Cigarette Use and Frequency and Intensity of Cigarette Smoking among South Korean Adolescents

    Directory of Open Access Journals (Sweden)

    Jung Ah Lee

    2017-03-01

    Full Text Available Introduction: The prevalence of adolescent electronic cigarette (e-cigarette use has increased in most countries. This study aims to determine the relation between the frequency of e-cigarette use and the frequency and intensity of cigarette smoking. Additionally, the study evaluates the association between the reasons for e-cigarette use and the frequency of its use. Materials and Methods: Using the 2015 Korean Youth Risk Behavior Web-Based Survey, we included 6655 adolescents with an experience of e-cigarette use who were middle and high school students aged 13–18 years. We compared smoking experience, the frequency and intensity of cigarette smoking, and the relation between the reasons for e-cigarette uses and the frequency of e-cigarette use. Results: The prevalence of e-cigarette ever and current (past 30 days users were 10.1% and 3.9%, respectively. Of the ever users, approximately 60% used e-cigarettes not within 1 month. On the other hand, 8.1% used e-cigarettes daily. The frequent and intensive cigarette smoking was associated with frequent e-cigarette uses. The percentage of frequent e-cigarette users (≥10 days/month was 3.5% in adolescents who did not smoke within a month, but 28.7% among daily smokers. Additionally, it was 9.1% in smokers who smoked less than 1 cigarette/month, but 55.1% in smokers who smoked ≥20 cigarettes/day. The most common reason for e-cigarette use was curiosity (22.9%, followed by the belief that they are less harmful than conventional cigarettes (18.9%, the desire to quit smoking (13.1%, and the capacity for indoor use (10.7%. Curiosity was the most common reason among less frequent e-cigarette users; however, the desire to quit smoking and the capacity for indoor use were the most common reasons among more frequent users. Conclusions: Results showed a positive relation between frequency or intensity of conventional cigarette smoking and the frequency of e-cigarette use among Korean adolescents, and

  15. First principles study of vibrational dynamics of ceria-titania hybrid clusters

    Energy Technology Data Exchange (ETDEWEB)

    Majid, Abdul, E-mail: abdulmajid40@yahoo.com; Bibi, Maryam [University of Gujrat, Department of Physics (Pakistan)

    2017-04-15

    Density functional theory based calculations were performed to study vibrational properties of ceria, titania, and ceria-titania hybrid clusters. The findings revealed the dominance of vibrations related to oxygen when compared to those of metallic atoms in the clusters. In case of hybrid cluster, the softening of normal modes related to exterior oxygen atoms in ceria and softening/hardening of high/low frequency modes related to titania dimmers are observed. The results calculated for monomers conform to symmetry predictions according to which three IR and three Raman active modes were detected for TiO{sub 2}, whereas two IR active and one Raman active modes were observed for CeO{sub 2}. The comparative analysis indicates that the hybrid cluster CeTiO{sub 4} contains simultaneous vibrational fingerprints of the component dimmers. The symmetry, nature of vibrations, IR and Raman activity, intensities, and atomic involvement in different modes of the clusters are described in detail. The study points to engineering of CeTiO{sub 4} to tailor its properties for technological visible region applications in photocatalytic and electrochemical devices.

  16. Vibration-Induced Errors in MEMS Tuning Fork Gyroscopes with Imbalance.

    Science.gov (United States)

    Fang, Xiang; Dong, Linxi; Zhao, Wen-Sheng; Yan, Haixia; Teh, Kwok Siong; Wang, Gaofeng

    2018-05-29

    This paper discusses the vibration-induced error in non-ideal MEMS tuning fork gyroscopes (TFGs). Ideal TFGs which are thought to be immune to vibrations do not exist, and imbalance between two gyros of TFGs is an inevitable phenomenon. Three types of fabrication imperfections (i.e., stiffness imbalance, mass imbalance, and damping imbalance) are studied, considering different imbalance radios. We focus on the coupling types of two gyros of TFGs in both drive and sense directions, and the vibration sensitivities of four TFG designs with imbalance are simulated and compared. It is found that non-ideal TFGs with two gyros coupled both in drive and sense directions (type CC TFGs) are the most insensitive to vibrations with frequencies close to the TFG operating frequencies. However, sense-axis vibrations with in-phase resonant frequencies of a coupled gyros system result in severe error outputs to TFGs with two gyros coupled in the sense direction, which is mainly attributed to the sense capacitance nonlinearity. With increasing stiffness coupled ratio of the coupled gyros system, the sensitivity to vibrations with operating frequencies is cut down, yet sensitivity to vibrations with in-phase frequencies is amplified.

  17. Bevel Gearbox Fault Diagnosis using Vibration Measurements

    Directory of Open Access Journals (Sweden)

    Hartono Dennis

    2016-01-01

    Full Text Available The use of vibration measurementanalysis has been proven to be effective for gearbox fault diagnosis. However, the complexity of vibration signals observed from a gearbox makes it difficult to accurately detectfaults in the gearbox. This work is based on a comparative studyof several time-frequency signal processing methods that can be used to extract information from transient vibration signals containing useful diagnostic information. Experiments were performed on a bevel gearbox test rig using vibration measurements obtained from accelerometers. Initially, thediscrete wavelet transform was implementedfor vibration signal analysis to extract the frequency content of signal from the relevant frequency region. Several time-frequency signal processing methods werethen incorporated to extract the fault features of vibration signals and their diagnostic performances were compared. It was shown thatthe Short Time Fourier Transform (STFT could not offer a good time resolution to detect the periodicity of the faulty gear tooth due the difficulty in choosing an appropriate window length to capture the impulse signal. The Continuous Wavelet Transform (CWT, on the other hand, was suitable to detection of vibration transients generated by localized fault from a gearbox due to its multi-scale property. However, both methods still require a thorough visual inspection. In contrast, it was shown from the experiments that the diagnostic method using the Cepstrumanalysis could provide a direct indication of the faulty tooth without the need of a thorough visual inspection as required by CWT and STFT.

  18. How exciton-vibrational coherences control charge separation in the photosystem II reaction center.

    Science.gov (United States)

    Novoderezhkin, Vladimir I; Romero, Elisabet; van Grondelle, Rienk

    2015-12-14

    In photosynthesis absorbed sun light produces collective excitations (excitons) that form a coherent superposition of electronic and vibrational states of the individual pigments. Two-dimensional (2D) electronic spectroscopy allows a visualization of how these coherences are involved in the primary processes of energy and charge transfer. Based on quantitative modeling we identify the exciton-vibrational coherences observed in 2D photon echo of the photosystem II reaction center (PSII-RC). We find that the vibrations resonant with the exciton splittings can modify the delocalization of the exciton states and produce additional states, thus promoting directed energy transfer and allowing a switch between the two charge separation pathways. We conclude that the coincidence of the frequencies of the most intense vibrations with the splittings within the manifold of exciton and charge-transfer states in the PSII-RC is not occurring by chance, but reflects a fundamental principle of how energy conversion in photosynthesis was optimized.

  19. Selective detection of crystalline cellulose in plant cell walls with sum-frequency-generation (SFG) vibration spectroscopy.

    Science.gov (United States)

    Barnette, Anna L; Bradley, Laura C; Veres, Brandon D; Schreiner, Edward P; Park, Yong Bum; Park, Junyeong; Park, Sunkyu; Kim, Seong H

    2011-07-11

    The selective detection of crystalline cellulose in biomass was demonstrated with sum-frequency-generation (SFG) vibration spectroscopy. SFG is a second-order nonlinear optical response from a system where the optical centrosymmetry is broken. In secondary plant cell walls that contain mostly cellulose, hemicellulose, and lignin with varying concentrations, only certain vibration modes in the crystalline cellulose structure can meet the noninversion symmetry requirements. Thus, SFG can be used to detect and analyze crystalline cellulose selectively in lignocellulosic biomass without extraction of noncellulosic species from biomass or deconvolution of amorphous spectra. The selective detection of crystalline cellulose in lignocellulosic biomass is not readily achievable with other techniques such as XRD, solid-state NMR, IR, and Raman analyses. Therefore, the SFG analysis presents a unique opportunity to reveal the cellulose crystalline structure in lignocellulosic biomass.

  20. [The effect of betahistine on histological changes in rabbit brain in model of whole body wide-frequency vibration].

    Science.gov (United States)

    Shimkus, Iu Iu; Sapegin, I D

    2013-01-01

    In acute experiments in conscious rabbits was studied protective action of selective blocker of histamine H3-receptor betahistine (2mg/kg i/v) against histological changes in precentral and postcentral gyrus, as well as in temporal lobe of cerebral cortex, thalamus, hypothalamus, and cerebellum, arising in case of modeling of whole body wide-frequency vibration. Betahistine attenuates edematous and degenerative changes in neurons and reciprocal glial reaction, caused by vibration, but does not eliminate edema in perivascular spaces. This effect may be related to the improvement of blood supply as a result of of vasodilatory action and decrease of oxygen consumption via vestibuloprotective effect.

  1. Combined IR-Raman vs vibrational sum-frequency heterospectral correlation spectroscopy

    Science.gov (United States)

    Roy, Sandra; Beutier, Clémentine; Hore, Dennis K.

    2018-06-01

    Vibrational sum-frequency generation spectroscopy is a valuable probe of surface structure, particularly when the same molecules are present in one of the adjacent bulk solid or solution phases. As a result of the non-centrosymmetric requirement of SFG, the signal generated is a marker of the extent to which the molecules are ordered in an arrangement that breaks the up-down symmetry at the surface. In cases where the accompanying changes in the bulk are of interest in understanding and interpreting the surface structure, simultaneous analysis of the bulk IR absorption or bulk Raman scattering is helpful, and may be used in heterospectral surface-bulk two-dimensional correlation. We demonstrate that, in such cases, generating a new type of bulk spectrum that combines the IR and Raman amplitudes is a better candidate than the individual IR and Raman spectra for the purpose of correlation with the SFG signal.

  2. The use of displacement threshold for switching frequency strategy for structural vibration mitigation

    International Nuclear Information System (INIS)

    Widjaja, Joko; Samali, Bijan; Li, Jianchun

    2007-01-01

    This paper presents a study of controllable real-time frequency shift using a fluid pin damper, so called 'smart pin', mounted at a beam-column connection. Unlike the stationary frequency shifter, the pin can increase or decrease the rotational stiffness of the connection, leading to an actively adjustable structural frequency due to real-time responses of polarised magneto-rheological (MR) fluid, whose rheological properties can change in milliseconds. The feedback to the pin damper governs the structural frequency changes. To demonstrate this concept, a single storey plane steel frame model with one hinge and one 'smart pin' damper, mounted at each beam-column connection and subjected to two scaled earthquake excitations, namely El-Centro 1940 and Northridge 1994, which respectively represent near- and farfield excitations, was tested using the shake table at the University of Technology, Sydney (UTS) structures laboratory, for 'proof-of-concept' investigation. Further, the dynamic performance of the model using a proposed switching strategy with a displacement threshold as an indicator for alternately supplied current level (flip-flop) was examined, assuming the earthquake records were known. The results showed some potential use of this control technique for structural vibration mitigation, however, further study to optimize the performance of the switching strategy is still required

  3. A Novel Ropes-DrivenWideband Piezoelectric Vibration Energy Harvester

    Directory of Open Access Journals (Sweden)

    Jinhui Zhang

    2016-12-01

    Full Text Available This paper presents a novel piezoelectric vibration energy harvester (PVEH in which a high-frequency generating beam (HFGB is driven by an array of low-frequency driving beams (LFDBs using ropes. Two mechanisms based on frequency upconversion and multimodal harvesting work together to broaden the frequency bandwidth of the proposed vibration energy harvester (VEH. The experimental results show that the output power of generating beam (GB remains unchanged with the increasing number of driving beams (DBs, compared with the traditional arrays of beams vibration energy harvester (AB-VEH, and the output power and bandwidth behavior can be adjusted by parameters such as acceleration, rope margin, and stiffness of LFDBs, which shows the potential to achieve unlimited wideband vibration energy-harvesting for a variable environment.

  4. Investigation of Concrete Floor Vibration Using Heel-Drop Test

    Science.gov (United States)

    Azaman, N. A. Mohd; Ghafar, N. H. Abd; Azhar, A. F.; Fauzi, A. A.; Ismail, H. A.; Syed Idrus, S. S.; Mokhjar, S. S.; Hamid, F. F. Abd

    2018-04-01

    In recent years, there is an increased in floor vibration problems of structures like residential and commercial building. Vibration is defined as a serviceability issue related to the comfort of the occupant or damage equipment. Human activities are the main source of vibration in the building and it could affect the human comfort and annoyance of residents in the building when the vibration exceed the recommend level. A new building, Madrasah Tahfiz located at Yong Peng have vibration problem when load subjected on the first floor of the building. However, the limitation of vibration occurs on building is unknown. Therefore, testing is needed to determine the vibration behaviour (frequency, damping ratio and mode shape) of the building. Heel-drop with pace 2Hz was used in field measurement to obtain the vibration response. Since, the heel-drop test results would vary in light of person performance, test are carried out three time to reduce uncertainty. Natural frequency from Frequency Response Function analysis (FRF) is 17.4Hz, 16.8, 17.4Hz respectively for each test.

  5. TCIQ: An identification by intensity and frequency of potent testing cues in science

    Science.gov (United States)

    Kermis, William J.

    Everyone experiences some anxiety while taking an examination. High-test-anxious (HTA) and low-test-anxious (LTA) students are described by two characteristic differences: frequency and intensity of anxious responses and attentional direction to testing cues. The purposes of this study were threefold: (1) to report potent testing cues (i.e., 90% response agreement for both intensity and frequency) that were identified by HTA and LTA students; (2) to report differences between HTA and LTA students for frequencies and intensities of responses to testing cues; and (3) to report differences between HTA and LTA students of attentional direction to testing cues. A pool of 396 males and females who were enrolled in physical geology completed the State-Trait Anxiety Inventory. A random sample consisting of 93 HTA and 40 LTA subjects completed the Test Cues Identification Questionnaire (TCIQ). The TCIQ consists of 28 disruptive items and 27 helpful items. Subjects responded with both frequency and intensity ratings for all of the 55 items in the TCIQ. Results revealed that 22 items were viewed by subjects as potent testing cues. Empirical evidence obtained did not support previous theoretical reports of differences between HTA and LTA students for either frequency and intensity of anxious responses or attentional direction to the set of disruptive and helpful testing cues. Although test anxiousness did not appear to be associated with those two characteristics differences, a discriminant analysis revealed 24 items in the TCIQ which significantly, 2 (24) = 47.59, p < 0.004, separated HTA and LTA subjects responses. Apparently, HTA and LTA students differ in their responses to specific disruptive and helpful cues but not in their responses to the set of testing cues as was previously postulated.

  6. Calculation of vibrational spectra of complex hydrides, LiBeH/sub 3/, NaBeH/sub 3/ and LiMgH/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Sukhanov, L P; Boldyrev, A I [AN SSSR, Chernogolovka. Inst. Novykh Khimicheskikh Problem

    1984-03-01

    The non-empirical Hartree-Fock-Ruthan method with a two-exponent Ros-Zigban basis has been used to calculate the coefficients of harmonic force field, frequency and intensity of normal vibrations of the LiBeH/sub 3/, NaBeH/sub 3/ and LiMgH/sub 3/ complex hydrides. Attribution of vibrational types is conducted. Isotope shifts for different isotope substitutions in the L(MH/sub 3/) are calculated. The effect of the nature of both the outer-spherical cation L/sup +/ and central atom M on the vibrational spectrum is discussed.

  7. Phonon vibrational frequencies of all single-wall carbon nanotubes at the lambda point: reduced matrix calculations.

    Science.gov (United States)

    Wang, Yufang; Wu, Yanzhao; Feng, Min; Wang, Hui; Jin, Qinghua; Ding, Datong; Cao, Xuewei

    2008-12-01

    With a simple method-the reduced matrix method, we simplified the calculation of the phonon vibrational frequencies according to SWNTs structure and their phonon symmetric property and got the dispersion properties of all SWNTs at Gamma point in Brillouin zone, whose diameters lie between 0.6 and 2.5 nm. The calculating time is shrunk about 2-4 orders. A series of the dependent relationships between the diameters of SWNTs and the frequencies of Raman and IR active modes are given. Several fine structures including "glazed tile" structures in omega approximately d figures are found, which might predict a certain macro-quantum phenomenon of the phonons in SWNTs.

  8. Ab initio and DFT studies of the structure and vibrational spectra of anhydrous caffeine

    Science.gov (United States)

    Srivastava, Santosh K.; Singh, Vipin B.

    2013-11-01

    Vibrational spectra and molecular structure of anhydrous caffeine have been systematically investigated by second order Moller-Plesset (MP2) perturbation theory and density functional theory (DFT) calculations. Vibrational assignments have been made and many previous ambiguous assignments in IR and Raman spectra are amended. The calculated DFT frequencies and intensities at B3LYP/6-311++G(2d,2p) level, were found to be in better agreement with the experimental values. It was found that DFT with B3LYP functional predicts harmonic vibrational wave numbers more close to experimentally observed value when it was performed on MP2 optimized geometry rather than DFT geometry. The calculated TD-DFT vertical excitation electronic energies of the valence excited states of anhydrous caffeine are found to be in consonance to the experimental absorption peaks.

  9. A proof-of-principle for frequency-domain vibration analysis

    International Nuclear Information System (INIS)

    Mobley, R.K.

    1987-01-01

    The economic and regulatory pressures on operating utilities to improve efficiency, availability, and reliability and to extend the effective operating life of existing electric power generating plants have created a real need for instrumentation, systems, and programs that can monitor, analyze, and provide the means to correct incipient machine and process problems. Predictive maintenance programs, properly utilized, can be one key to achieving these goals. Recent developments in microprocessor technology have provided the ability to routinely monitor the actual mechanical condition of all rotating and reciprocating machinery and process variables (i.e., pressure, temperature, flow, etc.) of other process equipment within an operating electric power generating plant. This direct correlation between frequency-domain vibration and actual mechanical condition of machinery and trending process variables of nonrotating equipment can provide the key to improving availability, reliability, and thermal efficiency and can provide the baseline information necessary for developing a realistic plan for extending the useful life of power plants. The premise of utilizing microprocessor-based predictive maintenance to improve power plant operation has been proven by a number of utilities

  10. Characterization of polymer surface structure and surface mechanical behaviour by sum frequency generation surface vibrational spectroscopy and atomic force microscopy

    International Nuclear Information System (INIS)

    Opdahl, Aric; Koffas, Telly S; Amitay-Sadovsky, Ella; Kim, Joonyeong; Somorjai, Gabor A

    2004-01-01

    Sum frequency generation (SFG) vibrational spectroscopy and atomic force microscopy (AFM) have been used to study polymer surface structure and surface mechanical behaviour, specifically to study the relationships between the surface properties of polymers and their bulk compositions and the environment to which the polymer is exposed. The combination of SFG surface vibrational spectroscopy and AFM has been used to study surface segregation behaviour of polyolefin blends at the polymer/air and polymer/solid interfaces. SFG surface vibrational spectroscopy and AFM experiments have also been performed to characterize the properties of polymer/liquid and polymer/polymer interfaces, focusing on hydrogel materials. A method was developed to study the surface properties of hydrogel contact lens materials at various hydration conditions. Finally, the effect of mechanical stretching on the surface composition and surface mechanical behaviour of phase-separated polyurethanes, used in biomedical implant devices, has been studied by both SFG surface vibrational spectroscopy and AFM. (topical review)

  11. Skeletal site-specific effects of whole body vibration in mature rats: from deleterious to beneficial frequency-dependent effects.

    Science.gov (United States)

    Pasqualini, Marion; Lavet, Cédric; Elbadaoui, Mohamed; Vanden-Bossche, Arnaud; Laroche, Norbert; Gnyubkin, Vasily; Vico, Laurence

    2013-07-01

    Whole body vibration (WBV) is receiving increasing interest as an anti-osteoporotic prevention strategy. In this context, selective effects of different frequency and acceleration magnitude modalities on musculoskeletal responses need to be better defined. Our aim was to investigate the bone effects of different vibration frequencies at constant g level. Vertical WBV was delivered at 0.7 g (peak acceleration) and 8, 52 or 90 Hz sinusoidal vibration to mature male rats 10 min daily for 5 days/week for 4 weeks. Peak accelerations measured by skin or bone-mounted accelerometers at L2 vertebral and tibia crest levels revealed similar values between adjacent skin and bone sites. Local accelerations were greater at 8 Hz compared with 52 and 90 Hz and were greater in vertebra than tibia for all the frequencies tested. At 52 Hz, bone responses were mainly seen in L2 vertebral body and were characterized by trabecular reorganization and stimulated mineral apposition rate (MAR) without any bone volume alteration. At 90 Hz, axial and appendicular skeletons were affected as were the cortical and trabecular compartments. Cortical thickness increased in femur diaphysis (17%) along with decreased porosity; trabecular bone volume increased at distal femur metaphysis (23%) and even more at L2 vertebral body (32%), along with decreased SMI and increased trabecular connectivity. Trabecular thickness increased at the tibia proximal metaphysis. Bone cellular activities indicated a greater bone formation rate, which was more pronounced at vertebra (300%) than at long bone (33%). Active bone resorption surfaces were unaffected. At 8 Hz, however, hyperosteoidosis with reduced MAR along with increased resorption surfaces occurred in the tibia; hyperosteoidosis and trend towards decreased MAR was also seen in L2 vertebra. Trabecular bone mineral density was decreased at femur and tibia. Thus the most favorable regimen is 90 Hz, while deleterious effects were seen at 8 Hz. We concluded that

  12. Natural frequencies, modeshapes and modal interactions for strings vibrating against an obstacle: Relevance to Sitar and Veena

    Science.gov (United States)

    Mandal, A. K.; Wahi, P.

    2015-03-01

    We study the vibration characteristics of a string with a smooth unilateral obstacle placed at one of the ends similar to the strings in musical instruments like sitar and veena. In particular, we explore the correlation between the string vibrations and some unique sound characteristics of these instruments like less inharmonicity in the frequencies, a large number of overtones and the presence of both frequency and amplitude modulations. At the obstacle, we have a moving boundary due to the wrapping of the string and an appropriate scaling of the spatial variable leads to a fixed boundary at the cost of introducing nonlinearity in the governing equation. Reduced order system of equations has been obtained by assuming a functional form for the string displacement which satisfies all the boundary conditions and gives the free length of the string in terms of the modal coordinates. To study the natural frequencies and mode-shapes, the nonlinear governing equation is linearized about the static configuration. The natural frequencies have been found to be harmonic and they depend on the shape of the obstacle through the effective free length of the string. Expressions have been obtained for the time-varying mode-shapes as well as the variation of the nodal points. Modal interactions due to coupling have been studied which show the appearance of higher overtones as well as amplitude modulations in our theoretical model akin to the experimental observations. All the obtained results have been verified with an alternate formulation based on the assumed mode method with polynomial shape functions.

  13. Vibrational tug-of-war: The pKA dependence of the broad vibrational features of strongly hydrogen-bonded carboxylic acids

    Science.gov (United States)

    Van Hoozen, Brian L.; Petersen, Poul B.

    2018-04-01

    Medium and strong hydrogen bonds give rise to broad vibrational features frequently spanning several hundred wavenumbers and oftentimes exhibiting unusual substructures. These broad vibrational features can be modeled from first principles, in a reduced dimensional calculation, that adiabatically separates low-frequency modes, which modulate the hydrogen bond length, from high-frequency OH stretch and bend modes that contribute to the vibrational structure. Previously this method was used to investigate the origin of an unusual vibrational feature frequently found in the spectra of dimers between carboxylic acids and nitrogen-containing aromatic bases that spans over 900 cm-1 and contains two broad peaks. It was found that the width of this feature largely originates from low-frequency modes modulating the hydrogen bond length and that the structure results from Fermi resonance interactions. In this report, we examine how these features change with the relative acid and base strength of the components as reflected by their aqueous pKA values. Dimers with large pKA differences are found to have features that can extend to frequencies below 1000 cm-1. The relationships between mean OH/NH frequency, aqueous pKA, and O-N distance are examined in order to obtain a more rigorous understanding of the origin and shape of the vibrational features. The mean OH/NH frequencies are found to correlate well with O-N distances. The lowest OH stretch frequencies are found in dimer geometries with O-N distances between 2.5 and 2.6 Å. At larger O-N distances, the hydrogen bonding interaction is not as strong, resulting in higher OH stretch frequencies. When the O-N distance is smaller than 2.5 Å, the limited space between the O and N determines the OH stretch frequency, which gives rise to frequencies that decrease with O-N distances. These two effects place a lower limit on the OH stretch frequency which is calculated to be near 700 cm-1. Understanding how the vibrational features

  14. Vibration of liquid-filled thin shells

    International Nuclear Information System (INIS)

    Kalnins, A.

    1979-01-01

    This paper describes the analysis of free and forced vibration of a thin, axisymmetric shell, which contains some liquid. The axis of symmetry is vertical. Only such vibration is considered which can be produced by a horizontal movement of the base of shell. The objective of this paper is to examine the response of the coupled shell-liquid system for a frequency range lying between zero and the lowest natural sloshing frequency of the liquid. The mass of the liquid is modeled by a stationary and one or more sloshing masses. It is shown how the stationary mass can be incorporated in the vibration analysis of the shell and how to natural frequency of the coupled shell-liquid system can be obtained from a simple formula, if the lowest natural frequency of the shell, plus the stationary mass of the liquid, can be determined. A numerical example is given. (orig.)

  15. Active vibration control for piezoelectricity cantilever beam: an adaptive feedforward control method

    Science.gov (United States)

    Zhu, Qiao; Yue, Jun-Zhou; Liu, Wei-Qun; Wang, Xu-Dong; Chen, Jun; Hu, Guang-Di

    2017-04-01

    This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) is utilized to reject the vibration with unknown multiple frequencies. First, the experiment setup and its mathematical model are introduced. Due to that the channel between the disturbance and the vibration output is unknown in practice, a concept of equivalent input disturbance (EID) is employed to put an equivalent disturbance into the input channel. In this situation, the vibration control can be achieved by setting the control input be the identified EID. Then, for the EID with known multiple frequencies, the AFC is introduced to perfectly reject the vibration but is sensitive to the frequencies. In order to accurately identify the unknown frequencies of EID in presence of the random disturbances and un-modeled nonlinear dynamics, the time-frequency-analysis (TFA) method is employed to precisely identify the unknown frequencies. Consequently, a TFA-based AFC algorithm is proposed to the active vibration control with unknown frequencies. Finally, four cases are given to illustrate the efficiency of the proposed TFA-based AFC algorithm by experiment.

  16. Vibration study of the APS magnet support assemblies

    International Nuclear Information System (INIS)

    Wambsganss, M.W.; Jendrzejczyk, J.A.; Chen, S.S.

    1990-11-01

    Stability of the positron closed orbit is a requirement for successful operation of the Advanced Photon Source. The fact that vibration of the storage ring quadrupole magnets can lead to distortion of the positron closed orbit and to potentially unacceptable beam emittance growth provides the motivation for the subject studies. Low frequency vibrations can be controlled with steering magnets using feedback systems, provided the vibration amplitudes are within the dynamic range of the controllers. High frequency vibration amplitudes, on the other hand, are out of the range of the controller and, therefore must be limited to ensure the emittance growth will not exceed a prescribed value. Vibration criteria were developed based on the requirement that emittance growth be limited to 10 percent. Recognizing that the quadrupole magnets have the most significant effect, three different scenarios were considered: vibration of a single quadrupole within the storage ring, random vibration of all the quadrupoles in the ring, and the hypothetical case of a plane wave sweeping across the site and the quadrupoles following the motion of the plane wave. The maximum allowable peak vibration amplitudes corresponding to these three vibration scenarios are given. The criteria associated with the passage of a plane wave is dependent on wavelength, or, alternatively, on frequency given the wave speed. The wave speed used is that measured as a part of the geotechnical investigation at the APS site

  17. [Influence of low-frequency magnetotherapy and HF-puncture on the heart rhythm in hypertensive workers exposed to vibration].

    Science.gov (United States)

    Drobyshev, V A; Loseva, M I; Sukharevskaia, T M; Michurin, A I

    2001-01-01

    The authors present results concerning use of low-frequency magnetic fields and HF-therapy for correction of vegetative homeostasis in workers with variable length of service, exposed to vibration, having early forms of arterial hypertension. The most positive changes of vegetative status and central hemodynamics are seen in workers with low length of service.

  18. Whole-body vibration improves neuromuscular parameters and functional capacity in osteopenic postmenopausal women.

    Science.gov (United States)

    Dutra, Milena C; de Oliveira, Mônica L; Marin, Rosangela V; Kleine, Hellen C R; Silva, Orivaldo L; Lazaretti-Castro, Marise

    2016-08-01

    In this longitudinal, paired-control study, we developed special vibration platforms to evaluate the effects of low-intensity vibration on neuromuscular function and functional capacity in osteopenic postmenopausal women. Women in the platform group (PG; n = 62) stood still and barefoot on the platform for 20 minutes, 5 times a week for 12 months. Each platform vibrated with a frequency of 60 Hz, intensity of 0.6g, and amplitude of less than 1 mm. Women in the control group (CG; n = 60) were followed up and instructed not to modify their physical activity during the study. Every 3 months all volunteers were invited to a visit to check for any change in their lifestyle. Assessments were performed at baseline and at 12 months, and included isometric muscle strength in the hip flexors and back extensors, right handgrip strength, dynamic upper limb strength (arm curl test), upper trunk flexibility (reach test [RT]), mobility (timed up and go test), and static balance (unipedal stance test). Statistical analyses were performed using the intention-to-treat strategy. Both groups were similar for all variables at baseline. At the end of intervention, the PG was significantly better than CG in all parameters but in the RT. When compared with baseline, after 12 months of vibration the PG presented statistically significant improvements in isometric and dynamic muscle strength in the hip flexors (+36.7%), back extensors (+36.5%), handgrip strength (+4.4%), arm curl test (+22.8%), RT (+9.9%), unipedal stance test (+6.8%), and timed up and go test (-9.2%), whereas the CG showed no significant differences during the same period of time. As such, there were no side effects related to the study procedures during the 12 months of intervention. Low-intensity vibration improved balance, motility, and muscle strength in the upper and lower limbs in postmenopausal women.

  19. Response characteristics of vibration-sensitive neurons in the midbrain of the grassfrog, Rana temporaria

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J; Jørgensen, M B

    1989-01-01

    European grassfrogs (Rana temporaria) were stimulated with pulsed sinusoidal, vertical vibrations (10-300 Hz) and the responses of 46 single midbrain neurons were recorded in awake, immobilized animals. Most units (40) had simple V-shaped excitatory vibrational tuning curves. The distribution of ...... stimuli probably play a role in communication and detection of predators and the vibration-sensitive midbrain neurons may be involved in the central processing of such behaviorally significant stimuli.......European grassfrogs (Rana temporaria) were stimulated with pulsed sinusoidal, vertical vibrations (10-300 Hz) and the responses of 46 single midbrain neurons were recorded in awake, immobilized animals. Most units (40) had simple V-shaped excitatory vibrational tuning curves. The distribution...... of best frequencies (BF's) was bimodal with peaks at 10 and 100 Hz and the thresholds ranged from 0.02 to 1.28 cm/s2 at the BF. Twenty-three neurons showed phasic-tonic and 11 neurons phasic responses. The dynamic range of seismic intensity for most neurons was 20-30 dB. In contrast to the sharp phase...

  20. High Frequency Vibration Based Fatigue Testing of Developmental Alloys

    Science.gov (United States)

    Holycross, Casey M.; Srinivasan, Raghavan; George, Tommy J.; Tamirisakandala, Seshacharyulu; Russ, Stephan M.

    Many fatigue test methods have been previously developed to rapidly evaluate fatigue behavior. This increased test speed can come at some expense, since these methods may require non-standard specimen geometry or increased facility and equipment capability. One such method, developed by George et al, involves a base-excited plate specimen driven into a high frequency bending resonant mode. This resonant mode is of sufficient frequency (typically 1200 to 1700 Hertz) to accumulate 107 cycles in a few hours. One of the main limitations of this test method is that fatigue cracking is almost certainly guaranteed to be surface initiated at regions of high stress. This brings into question the validity of the fatigue test results, as compared to more traditional uniaxial, smooth-bar testing, since high stresses are subjecting only a small volume to fatigue damage. This limitation also brings into question the suitability of this method to screen developmental alloys, should their initiation life be governed by subsurface flaws. However, if applicable, the rapid generation of fatigue data using this method would facilitate faster design iterations, identifying more quickly, material and manufacturing process deficiencies. The developmental alloy used in this study was a powder metallurgy boron-modified Ti-6Al-4V, a new alloy currently being considered for gas turbine engine fan blades. Plate specimens were subjected to fully reversed bending fatigue. Results are compared with existing data from commercially available Ti-6Al-4V using both vibration based and more traditional fatigue test methods.

  1. Vibration test report on the instrumented capsule for fuel irradiation test

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jeong Soo; Yoon, D. B.; Wu, J. S.; Oh, J. M.; Park, S. J.; Cho, M. S.; Kim, B. G.; Kang, Y. W

    2003-01-01

    The fluid-induced vibration level of instrumented capsule, which was manufactured for fuel irradiation test at the reactor core of HANARO, was investigated. For this purpose, the instrumented capsule was loaded at the OR site of the HANARO design verification test facility that could simulate identical flow condition as the HANARO core. Then, vibration signals of the instrumented capsule subjected to various flow conditions were measured by using vibration sensors. In time domain analysis, maximum amplitudes and RMS values of the measured acceleration and displacement signals were obtained. By using frequency domain analysis, frequency components of the fluid-induced vibration were analyzed. In addition, natural frequencies of the instrumented capsule were obtained by performing modal test. The frequency analysis results showed that the natural frequency components near 7.5Hz and 17.5Hz were dominant in the fluid-induced vibration signal. The maximum amplitude of the accelerations was measured as 12.04m/s{sup 2} that is within the allowable vibrational limit(18.99m/s{sup 2})of the reactor structure. Also, the maximum displacement amplitude was calculated as 0.191mm. Since these vibration levels are remarkably low, excessive vibration is not expected when the irradiation test of the instrumented capsule is performed at the HANARO core.

  2. Electromagnetic Vibration Energy Harvesting for Railway Applications

    Directory of Open Access Journals (Sweden)

    Bradai S.

    2018-01-01

    Full Text Available Safe localization of trains via GPS and wireless sensors is essential for railway traffic supervision. Especially for freight trains and because normally no power source is available on the wagons, special solutions for energy supply have to be developed based on energy harvesting techniques. Since vibration is available in this case, it provides an interesting source of energy. Nevertheless, in order to have an efficient design of the harvesting system, the existing vibration needs to be investigated. In this paper, we focus on the characterization of vibration parameters in railway application. We propose an electromagnetic vibration converter especially developed to this application. Vibration profiles from a train traveling between two German cities were measured using a data acquisition system installed on the train’s wagon. Results show that the measured profiles present multiple frequency signals in the range of 10 to 50 Hz and an acceleration of up to 2 g. A prototype for a vibration converter is designed taking into account the real vibration parameters, robustness and integrability requirements. It is based on a moving coil attached to a mechanical spring. For the experimental emulation of the train vibrations, a shaker is used as an external artificial vibration source controlled by a laser sensor in feedback. A maximum voltage of 1.7 V peak to peak which corresponds to a maximum of 10 mW output power where the applied excitation frequency is close to the resonant frequency of the converter which corresponds to 27 Hz.

  3. A second, low-frequency mode of vibration in the intact mammalian cochlea.

    Science.gov (United States)

    Lukashkin, Andrei N; Russell, Ian J

    2003-03-01

    The mammalian cochlea is a structure comprising a number of components connected by elastic elements. A mechanical system of this kind is expected to have multiple normal modes of oscillation and associated resonances. The guinea pig cochlear mechanics was probed using distortion components generated in the cochlea close to the place of overlap between two tones presented simultaneously. Otoacoustic emissions at frequencies of the distortion components were recorded in the ear canal. The phase behavior of the emissions reveals the presence of a nonlinear resonance at a frequency about a half octave below that of the high-frequency primary tone. The location of the resonance is level dependent and the resonance shifts to lower frequencies with increasing stimulus intensity. This resonance is thought to be associated with the tectorial membrane. The resonance tends to minimize input to the cochlear receptor cells at frequencies below the high-frequency primary and increases the dynamic load to the stereocilia of the receptor cells at the primary frequency when the tectorial membrane and reticular lamina move in counterphase.

  4. Attitudes Toward, and Use of, Vibrators in China

    OpenAIRE

    Jing, S.; Lay, A.; Weis, L.; Furnham, A.

    2018-01-01

    The current study examined the relationship between traditional masculine traits and attitudes toward vibrator use, actual vibrator use, and frequency of vibrator use in China. In all, 235 Chinese females aged between 16 and 58 years completed a questionnaire regarding attitudes toward, and personal use of, vibrators. The results showed a positive association between masculine traits and attitudes toward women's vibrator use, attitudes toward vibrator use and actual vibrator use, as well as f...

  5. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  6. Distributed Weak Fiber Bragg Grating Vibration Sensing System Based on 3 × 3 Fiber Coupler

    Science.gov (United States)

    Li, Wei; Zhang, Jian

    2018-06-01

    A novel distributed weak fiber Bragg gratings (FBGs) vibration sensing system has been designed to overcome the disadvantages of the conventional methods for optical fiber sensing networking, which are: low signal intensity in the usually adopted time-division multiplexing (TDM) technology, insufficient quantity of multiplexed FBGs in the wavelength-division multiplexing (WDM) technology, and that the mixed WDM/TDM technology measures only the physical parameters of the FBG locations but cannot perform distributed measurement over the whole optical fiber. This novel system determines vibration events in the optical fiber line according to the intensity variation of the interference signals between the adjacent weak FBG reflected signals and locates the vibration points accurately using the TDM technology. It has been proven by tests that this system performs vibration signal detection and demodulation in a way more convenient than the conventional methods for the optical fiber sensing system. It also measures over the whole optical fiber, therefore, distributed measurement is fulfilled, and the system locating accuracy is up to 20 m, capable of detecting any signals of whose drive signals lower limit voltage is 0.2 V while the frequency range is 3 Hz‒1 000 Hz. The system has the great practical significance and application value for perimeter surveillance systems.

  7. Reducing vibration transfer from power plants by active methods

    Science.gov (United States)

    Kiryukhin, A. V.; Milman, O. O.; Ptakhin, A. V.

    2017-12-01

    The possibility of applying the methods of active damping of vibration and pressure pulsations for reducing their transfer from power plants into the environment, the seating, and the industrial premises are considered. The results of experimental works implemented by the authors on the active broadband damping of vibration and dynamic forces after shock-absorption up to 15 dB in the frequency band up to 150 Hz, of water pressure pulsations in the pipeline up to 20 dB in the frequency band up to 600 Hz, and of spatial low-frequency air noise indoors of a diesel generator at discrete frequency up to 20 dB are presented. It is shown that a reduction of vibration transfer through a vibration-isolating junction (expansion joints) of pipelines with liquid is the most complicated and has hardly been developed so far. This problem is essential for vibration isolation of power equipment from the seating and the environment through pipelines with water and steam in the power and transport engineering, shipbuilding, and in oil and gas pipelines in pumping stations. For improving efficiency, reducing the energy consumption, and decreasing the overall dimensions of equipment, it is advisable to combine the work of an active system with passive damping means, the use of which is not always sufficient. The executive component of the systems of active damping should be placed behind the vibration isolators (expansion joints). It is shown that the existence of working medium and connection of vibration with pressure pulsations in existing designs of pipeline expansion joints lead to growth of vibration stiffness of the expansion joint with the environment by two and more orders as compared with the static stiffness and makes difficulties for using the active methods. For active damping of vibration transfer through expansion joints of pipelines with a liquid, it is necessary to develop expansion joint structures with minimal connection of vibrations and pulsations and minimal

  8. Adjustable Nonlinear Springs to Improve Efficiency of Vibration Energy Harvesters

    OpenAIRE

    Boisseau, S.; Despesse, G.; Seddik, B. Ahmed

    2012-01-01

    Vibration Energy Harvesting is an emerging technology aimed at turning mechanical energy from vibrations into electricity to power microsystems of the future. Most of present vibration energy harvesters are based on a mass spring structure introducing a resonance phenomenon that allows to increase the output power compared to non-resonant systems, but limits the working frequency bandwidth. Therefore, they are not able to harvest energy when ambient vibrations' frequencies shift. To follow sh...

  9. Transverse Resonant Vibration of Non-Bearing Structures Caused by Wind

    Science.gov (United States)

    Jendzelovsky, Norbert; Antal, Roland

    2017-10-01

    Nowadays, there are increasing use of very thin, subtle and light structures in the field of building constructions. We can find such a structures as part of roofs or design facades. By using these lamellas like, non-bearing structures as a part of architectural design of buildings, it is necessary to consider wind effects on these structures. Subtle structures of this type are prone to vibration in the transverse direction of the wind flow. The fact that the vibration occurs depends on wind parameters (wind velocity, direction of an air flow) and it also depends on the properties of lamella (shape, length, mass, natural frequency, support type). The principal idea of this article is to show susceptibility of lamellae-like structures to transverse resonant vibration caused by the phenomenon called Von Karman effect. Comparison of susceptibility to transverse resonance vibration was analysed on the different shapes of lamellas loaded by different wind speed. Analysis was based on usage of empirically derived equations. Von Karman effect arise from wind flow past an object. Turbulence in the form of vortices are formed at the object and shed into the flowing stream intermittently. The potential problem is that this turbulence can induce vibrations into the lamella itself. In terms of this vibration problem, two frequencies are interesting. Von Karman shedding frequency is the frequency at which the vortices are formed and shed at the object. The vortex-shedding frequency increases with the velocity of the wind flow and decreases with the size of the object. Natural frequency of the object depends on the construction of the lamella itself. Parameters of lamella as a shape, mass, length, elasticity modulus of material and support types are directly involved in the calculation of natural frequency. Worst case scenario in the term of transverse resonant vibration occurs when the natural frequency of lamella is equal to the vortex-shedding frequency. In this case

  10. Vertical Vibration Characteristics of a High-Temperature Superconducting Maglev Vehicle System

    Science.gov (United States)

    Jiang, Jing; Li, Ke Cai; Zhao, Li Feng; Ma, Jia Qing; Zhang, Yong; Zhao, Yong

    2013-06-01

    The vertical vibration characteristics of a high-temperature superconducting maglev vehicle system are investigated experimentally. The displacement variations of the maglev vehicle system are measured with different external excitation frequency, in the case of a certain levitation gap. When the external vibration frequency is low, the amplitude variations of the response curve are small. With the increase of the vibration frequency, chaos status can be found. The resonance frequencies with difference levitation gap are also investigated, while the external excitation frequency range is 0-100 Hz. Along with the different levitation gap, resonance frequency is also different. There almost is a linear relationship between the levitation gap and the resonance frequency.

  11. Research on Free Vibration Frequency Characteristics of Rotating Functionally Graded Material Truncated Conical Shells with Eccentric Functionally Graded Material Stringer and Ring Stiffeners

    Directory of Open Access Journals (Sweden)

    Dao Van Dung

    Full Text Available Abstract In this research work, an exact analytical solution for frequency characteristics of the free vibration of rotating functionally graded material (FGM truncated conical shells reinforced by eccentric FGM stringers and rings has been investigated by the displacement function method. Material properties of shell and stiffeners are assumed to be graded in the thickness direction according to a simple power law distribution. The change of spacing between stringers is considered. Using the Donnell shell theory, Leckhnisky smeared stiffeners technique and taking into account the influences of centrifugal force and Coriolis acceleration the governing equations are derived. For stiffened FGM conical shells, it is difficult that free vibration equations are a couple set of three variable coefficient partial differential equations. By suitable transformations and applying Galerkin method, this difficulty is overcome in the paper. The sixth order polynomial equation for w is obtained and it is used to analyze the frequency characteristics of rotating ES-FGM conical shells. Effects of stiffener, geometrics parameters, cone angle, vibration modes and rotating speed on frequency characteristics of the shell forward and backward wave are discussed in detail. The present approach proves to be reliable and accurate by comparing with published results available in the literature.

  12. Fast Fourier transformation in vibration analysis of physically active systems

    International Nuclear Information System (INIS)

    Hafeez, T.; Amir, M.; Farooq, U.; Day, P.

    2003-01-01

    Vibration of all physical systems may be expressed as the summation of an infinite number of sine and cosine terms known as Fourier series. The basic vibration analysis tool used is the frequency 'spectrum' (a graph of vibration where the amplitude of vibration is plotted against frequency). When a particular rotating component begins to fail, its vibration tends to increase. Spectra graphs are powerful diagnostic tool for detecting components' degradation. Spectra obtained with accelerometers located at the various locations on the components and their analysis in practice from rotating machines enable early detecting of incipient failure. Consequence of unexpected failure can be catastrophic and costly. This study provides basis to relate defective component by its constituent frequencies and then to the known discrete frequency of its 'signature' or 'thumbprint' to predict and verify the sustained dynamic behavior of machine designs harmful effects of forced vibration. The spectra for gearbox of a vane with teeth damaged fault are presented here which signified the importance of FFT analysis as diagnostic tool. This may be helpful to predictive maintenance of the machinery. (author)

  13. Theoretical studies for the N2–N2O van der Waals complex: The potential energy surface, intermolecular vibrations, and rotational transition frequencies

    International Nuclear Information System (INIS)

    Zheng, Rui; Zheng, Limin; Yang, Minghui; Lu, Yunpeng

    2015-01-01

    Theoretical studies of the potential energy surface (PES) and bound states are performed for the N 2 –N 2 O van der Waals (vdW) complex. A four-dimensional intermolecular PES is constructed at the level of single and double excitation coupled-cluster method with a non-iterative perturbation treatment of triple excitations [CCSD(T)] with aug-cc-pVTZ basis set supplemented with bond functions. Two equivalent T-shaped global minima are located, in which the O atom of N 2 O monomer is near the N 2 monomer. The intermolecular fundamental vibrational states are assigned by inspecting the orientation of the nodal surface of the wavefunctions. The calculated frequency for intermolecular disrotation mode is 23.086 cm −1 , which is in good agreement with the available experimental data of 22.334 cm −1 . A negligible tunneling splitting with the value of 4.2 MHz is determined for the ground vibrational state and the tunneling splitting increases as the increment of the vibrational frequencies. Rotational levels and transition frequencies are calculated for both isotopomers 14 N 2 –N 2 O and 15 N 2 –N 2 O. The accuracy of the PES is validated by the good agreement between theoretical and experimental results for the transition frequencies and spectroscopic parameters

  14. The vibrational Jahn–Teller effect in E⊗e systems

    Energy Technology Data Exchange (ETDEWEB)

    Thapaliya, Bishnu P.; Dawadi, Mahesh B.; Ziegler, Christopher; Perry, David S., E-mail: dperry@uakron.edu

    2015-10-16

    Highlights: • The vibrational Jahn–Teller effect is documented for three E⊗e molecular systems. • The spontaneous vibrational Jahn–Teller distortion is very small. • Vibrational Jahn–Teller splittings are substantial (1–60 cm{sup −1}). • Vibrational conical intersections in CH{sub 3}OH are accessible at low energies. - Abstract: The Jahn–Teller theorem is applied in the vibrational context where degenerate high-frequency vibrational states (E) are considered as adiabatic functions of low-frequency vibrational coordinates (e). For CH{sub 3}CN and Cr(C{sub 6}H{sub 6})(CO){sub 3}, the global minimum of the non-degenerate electronic potential energy surface occurs at the C{sub 3v} geometry, but in CH{sub 3}OH, the equilibrium geometry is far from the C{sub 3v} reference geometry. In the former cases, the computed spontaneous Jahn–Teller distortion is exceptionally small. In methanol, the vibrational Jahn–Teller interaction results in the splitting of the degenerate E-type CH stretch into what have been traditionally assigned as the distinct ν{sub 2} and ν{sub 9} vibrational bands. The ab initio vibrational frequencies are fit precisely by a two-state high-order Jahn–Teller Hamiltonian (Viel and Eisfeld, 2004). The presence of vibrational conical intersections, including 7 for CH{sub 3}OH, has implications for spectroscopy, for geometric phase, and for ultrafast localized non-adiabatic energy transfer.

  15. Effect of vibration on microstructures and mechanical properties of 304 stainless steel GTA welds

    Science.gov (United States)

    Hsieh, Chih-Chun; Lai, Chien-Hong; Wu, Weite

    2013-07-01

    This study investigates the microstructures and mechanical properties of 304 stainless steel at various vibration frequencies during simultaneous vibration welding. The experimental results demonstrated that simultaneous vibration welding could accelerate the nucleation and grain refinement of the microstructures. The effect of the grain refinement was more evident at the resonant frequency (375 Hz) and a minimum content of residual δ-ferrite (4.0%). The γ phase grew in the preferential orientation of the (111) direction with and without vibration. The full width at half maximum of the diffraction peak widened after the vibration, which was attributed to the grain refinement. The residual stress could be efficiently removed through simultaneous vibration welding when the amplitude of the vibration was increased. Furthermore, the lowest residual stress (139 MPa) was found when the vibration frequency was 375 Hz. The hardness and Young's modulus exhibited slight increases with low and medium frequencies. The hardness values were increased by 7.6% and Young's modulus was increased by 15% when the vibration frequency was resonant (375 Hz).

  16. Submillimeter vibrationally excited water emission from the peculiar red supergiant VY Canis Majoris

    Science.gov (United States)

    Menten, K. M.; Philipp, S. D.; Güsten, R.; Alcolea, J.; Polehampton, E. T.; Brünken, S.

    2006-08-01

    Context: .Vibrationally excited emission from the SiO and H2O molecules probes the innermost circumstellar envelopes of oxygen-rich red giant and supergiant stars. VY CMa is the most prolific known emission source in these molecules. Aims: .Observations were made to search for rotational lines in the lowest vibrationally excited state of H2O. Methods: .The APEX telescope was used for observations of H2O lines at frequencies around 300 GHz. Results: .Two vibrationally excited H2O lines were detected, a third one could not be found. In one of the lines we find evidence for weak maser action, similar to known (sub)millimeter ν2 = 1 lines. We find that the other line's intensity is consistent with thermal excitation by the circumstellar infrared radiation field. Several SiO lines were detected together with the H2O lines.

  17. Equilibrium structure and atomic vibrations of Nin clusters

    Science.gov (United States)

    Borisova, Svetlana D.; Rusina, Galina G.

    2017-12-01

    The equilibrium bond lengths and binding energy, second differences in energy and vibrational frequencies of free clusters Nin (2 ≤ n ≤ 20) were calculated with the use of the interaction potential obtained in the tight-binding approximation (TBA). The results show that the minimum vibration frequency plays a significant role in the evaluation of the dynamic stability of the clusters. A nonmonotonic dependence of the minimum vibration frequency of clusters on their size and the extreme values for the number of atoms in a cluster n = 4, 6, 13, and 19 are demonstrated. This result agrees with the theoretical and experimental data on stable structures of small metallic clusters.

  18. Magnetically levitated autoparametric broadband vibration energy harvesting

    International Nuclear Information System (INIS)

    Kurmann, L.; Jia, Y.; Manoli, Y.; Woias, P.

    2016-01-01

    Some of the lingering challenges within the current paradigm of vibration energy harvesting (VEH) involve narrow operational frequency range and the inevitable non-resonant response from broadband noise excitations. Such VEHs are only suitable for limited applications with fixed sinusoidal vibration, and fail to capture a large spectrum of the real world vibration. Various arraying designs, frequency tuning schemes and nonlinear vibratory approaches have only yielded modest enhancements. To fundamentally address this, the paper proposes and explores the potentials in using highly nonlinear magnetic spring force to activate an autoparametric oscillator, in order to realize an inherently broadband resonant system. Analytical and numerical modelling illustrate that high spring nonlinearity derived from magnetic levitation helps to promote the 2:1 internal frequency matching required to activate parametric resonance. At the right internal parameters, the resulting system can intrinsically exhibit semi-resonant response regardless of the bandwidth of the input vibration, including broadband white noise excitation. (paper)

  19. Vibration energy harvester with low resonant frequency based on flexible coil and liquid spring

    Science.gov (United States)

    Wang, Y.; Zhang, Q.; Zhao, L.; Tang, Y.; Shkel, A.; Kim, E. S.

    2016-11-01

    This paper reports an electromagnetic vibration-energy harvester with low resonant frequency based on liquid spring composed of ferrofluid. Cylinder magnet array formed by four disc NdFeB magnets is suspended by ferrofluid in a laser-machined acrylic tube which is wrapped by flexible planar coil fabricated with microfabrication process. The magnet array and coil are aligned automatically by the ferrofluid. Restoring force when the magnet array is deviated from the balance position is proportional to the deviated distance, which makes the ferrofluid work as a liquid spring obeying Hook's law. Experimental results show that the electromagnetic energy harvester occupying 1.8 cc and weighing 5 g has a resonant frequency of 16 Hz and generates an induced electromotive force of Vrms = 2.58 mV (delivering 79 nW power into matched load of 21 Ω) from 3 g acceleration at 16 Hz.

  20. The Relation between Frequency of E-Cigarette Use and Frequency and Intensity of Cigarette Smoking among South Korean Adolescents

    OpenAIRE

    Jung Ah Lee; Sungkyu Lee; Hong-Jun Cho

    2017-01-01

    Introduction: The prevalence of adolescent electronic cigarette (e-cigarette) use has increased in most countries. This study aims to determine the relation between the frequency of e-cigarette use and the frequency and intensity of cigarette smoking. Additionally, the study evaluates the association between the reasons for e-cigarette use and the frequency of its use. Materials and Methods: Using the 2015 Korean Youth Risk Behavior Web-Based Survey, we included 6655 adolescents with an exper...

  1. Passive and active vibration isolation systems using inerter

    Science.gov (United States)

    Alujević, N.; Čakmak, D.; Wolf, H.; Jokić, M.

    2018-03-01

    This paper presents a theoretical study on passive and active vibration isolation schemes using inerter elements in a two degree of freedom (DOF) mechanical system. The aim of the work is to discuss basic capabilities and limitations of the vibration control systems at hand using simple and physically transparent models. Broad frequency band dynamic excitation of the source DOF is assumed. The purpose of the isolator system is to prevent vibration transmission to the receiving DOF. The frequency averaged kinetic energy of the receiving mass is used as the metric for vibration isolation quality. It is shown that the use of inerter element in the passive vibration isolation scheme can enhance the isolation effect. In the active case, a feedback disturbance rejection scheme is considered. Here, the error signal is the receiving body absolute velocity which is directly fed to a reactive force actuator between the source and the receiving bodies. In such a scheme, the so-called subcritical vibration isolation problems exist. These problems are characterised by the uncoupled natural frequency of the receiving body larger than the uncoupled natural frequency of the source body. In subcritical vibration isolation problems, the performance of the active control is limited by poor stability margins. This is because the stable feedback gain is restricted in a narrow range between a minimum and a maximum. However, with the inclusion of an inerter in the isolator, one of the two stability margins can be opened. This enables large, theoretically unlimited negative feedback gains and large active damping of the receiving body vibration. A simple expression for the required inertance is derived.

  2. Relative importance of precipitation frequency and intensity in inter-annual variation of precipitation in Singapore during 1980-2013

    Science.gov (United States)

    Li, Xin; Babovic, Vladan

    2017-04-01

    Observed studies on inter-annual variation of precipitation provide insight into the response of precipitation to anthropogenic climate change and natural climate variability. Inter-annual variation of precipitation results from the concurrent variations of precipitation frequency and intensity, understanding of the relative importance of frequency and intensity in the variability of precipitation can help fathom its changing properties. Investigation of the long-term changes of precipitation schemes has been extensively carried out in many regions across the world, however, detailed studies of the relative importance of precipitation frequency and intensity in inter-annual variation of precipitation are still limited, especially in the tropics. Therefore, this study presents a comprehensive framework to investigate the inter-annual variation of precipitation and the dominance of precipitation frequency and intensity in a tropical urban city-state, Singapore, based on long-term (1980-2013) daily precipitation series from 22 rain gauges. First, an iterative Mann-Kendall trend test method is applied to detect long-term trends in precipitation total, frequency and intensity at both annual and seasonal time scales. Then, the relative importance of precipitation frequency and intensity in inducing the inter-annual variation of wet-day precipitation total is analyzed using a dominance analysis method based on linear regression. The results show statistically significant upward trends in wet-day precipitation total, frequency and intensity at annual time scale, however, these trends are not evident during the monsoon seasons. The inter-annual variation of wet-day precipitation is mainly dominated by precipitation intensity for most of the stations at annual time scale and during the Northeast monsoon season. However, during the Southwest monsoon season, the inter-annual variation of wet-day precipitation is mainly dominated by precipitation frequency. These results have

  3. Bayesian Inference of Nonstationary Precipitation Intensity-Duration-Frequency Curves for Infrastructure Design

    Science.gov (United States)

    2016-03-01

    each IDF curve and subsequently used to force a calibrated and validated precipitation - runoff model. Probability-based, risk-informed hydrologic...ERDC/CHL CHETN-X-2 March 2016 Approved for public release; distribution is unlimited. Bayesian Inference of Nonstationary Precipitation Intensity...based means by which to develop local precipitation Intensity-Duration-Frequency (IDF) curves using historical rainfall time series data collected for

  4. Bandshapes in vibrational spectroscopy

    International Nuclear Information System (INIS)

    Dijkman, F.G.

    1978-01-01

    A detailed account is given of the development of modern bandshape theories since 1965. An investigation into the relative contributions of statistical irreversible relaxation processes is described, for a series of molecules in which gradually the length of one molecular axis is increased. An investigation into the theoretical and experimental investigation of the broadening brought about by the effect of fluctuating intermolecular potentials on the vibrational frequency is also described. The effect of an intermolecular perturbative potential on anharmonic and Morse oscillators is discussed and the results are presented of a computation on the broadening of the vibrational band of some diatomic molecules in a rigid lattice type solvent. The broadening of the OH-stretching vibration in a number of aliphatic alcohols, the vibrational bandshapes of the acetylenic C-H stretching vibration and of the symmetric methyl stretching vibration are investigated. (Auth./ C.F.)

  5. Two-phase flow induced parametric vibrations in structural systems

    International Nuclear Information System (INIS)

    Hara, Fumio

    1980-01-01

    This paper is divided into two parts concerning piping systems and a nuclear fuel pin system. The significant experimental results concerning the random vibration induced in an L-shaped pipe by air-water two-phase flow and the theoretical analysis of the vibration are described in the first part. It was clarified for the first time that the parametric excitation due to the periodic changes of system mass, centrifugal force and Coriolis force was the mechanism of exciting the vibration. Moreover, the experimental and theoretical analyses of the mechanism of exciting vibration by air-water two-phase flow in a straight, horizontal pipe were carried out, and the first natural frequency of the piping system was strongly related to the dominant frequency of void signals. The experimental results on the vibration of a nuclear fuel pin model in parallel air-water two-phase flow are reported in the latter part. The relations between vibrational strain variance and two-phase flow velocity or pressure fluctuation, and the frequency characteristics of vibrational strain variance were obtained. The theoretical analysis of the dynamic interaction between air-water two-phase flow and a fuel pin structure, and the vibrational instability of fuel pins in alternate air and water slugs or in large bubble flow are also reported. (Kako, I.)

  6. Systematic studies of molecular vibrational anharmonicity and vibration-rotation interaction by self-consistent-field higher derivative methods: Applications to asymmetric and symmetric top and linear polyatomic molecules

    International Nuclear Information System (INIS)

    Clabo, D.A. Jr.

    1987-04-01

    Inclusion of the anharmonicity normal mode vibrations [i.e., the third and fourth (and higher) derivatives of a molecular Born-Oppenheimer potential energy surface] is necessary in order to theoretically reproduce experimental fundamental vibrational frequencies of a molecule. Although ab initio determinations of harmonic vibrational frequencies may give errors of only a few percent by the inclusion of electron correlation within a large basis set for small molecules, in general, molecular fundamental vibrational frequencies are more often available from high resolution vibration-rotation spectra. Recently developed analytic third derivatives methods for self-consistent-field (SCF) wavefunctions have made it possible to examine with previously unavailable accuracy and computational efficiency the anharmonic force fields of small molecules

  7. Systematic studies of molecular vibrational anharmonicity and vibration-rotation interaction by self-consistent-field higher derivative methods: Applications to asymmetric and symmetric top and linear polyatomic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Clabo, D.A. Jr.

    1987-04-01

    Inclusion of the anharmonicity normal mode vibrations (i.e., the third and fourth (and higher) derivatives of a molecular Born-Oppenheimer potential energy surface) is necessary in order to theoretically reproduce experimental fundamental vibrational frequencies of a molecule. Although ab initio determinations of harmonic vibrational frequencies may give errors of only a few percent by the inclusion of electron correlation within a large basis set for small molecules, in general, molecular fundamental vibrational frequencies are more often available from high resolution vibration-rotation spectra. Recently developed analytic third derivatives methods for self-consistent-field (SCF) wavefunctions have made it possible to examine with previously unavailable accuracy and computational efficiency the anharmonic force fields of small molecules.

  8. Lucid Dreaming: Intensity, But Not Frequency, Is Inversely Related to Psychopathology

    Directory of Open Access Journals (Sweden)

    Liat Aviram

    2018-03-01

    Full Text Available Lucid dreaming (LD is awareness that one is dreaming, during the dream state. However, some define and assess LD relying also on controlling dream events, although control is present only in a subset of lucid dreams. LD has been claimed to represent well-being, and has even been used as a therapeutic agent. Conversely, LD is associated with mixed sleep-wake states, which are related to bizarre cognitions, stress, and psychopathology, and have been construed as arousal permeating and disrupting sleep. We propose that previous conflicting findings regarding relations between LD and both psychopathology and well-being, stem from the non-differentiated assessment of frequency and control. The present study aimed to develop an expansive measure of several LD characteristics (the Frequency and Intensity Lucid Dream questionnaire; FILD, and explore their relations with symptomatology. Undergraduate students (N = 187 self-reported trait LD, psychopathology (depression, anxiety, obsessive-compulsive symptoms, dissociation, and schizotypy, stress, and sleep problems; 2 months later, a subsample (n = 78 reported psychopathology again, and also completed a dream diary each morning for 14 days. Preliminary evidence supports the reliability and validity of the FILD. Items converged into four domains: frequency, intensity (e.g., control, activity, certainty of dreaming, emotional valence, and the use of induction techniques. We report an optimal frequency cutoff score to identify those likely to experience LD within a 2-week period. Whereas LD frequency was unrelated to psychopathology, LD intensity, and positive LD emotions, were inversely associated with several psychopathological symptoms. Use of deliberate induction techniques was positively associated with psychopathology and sleep problems. Additionally, we demonstrated directionality by employing a prospective-longitudinal design, showing that deliberate LD induction predicted an increase in

  9. Lucid Dreaming: Intensity, But Not Frequency, Is Inversely Related to Psychopathology

    Science.gov (United States)

    Aviram, Liat; Soffer-Dudek, Nirit

    2018-01-01

    Lucid dreaming (LD) is awareness that one is dreaming, during the dream state. However, some define and assess LD relying also on controlling dream events, although control is present only in a subset of lucid dreams. LD has been claimed to represent well-being, and has even been used as a therapeutic agent. Conversely, LD is associated with mixed sleep-wake states, which are related to bizarre cognitions, stress, and psychopathology, and have been construed as arousal permeating and disrupting sleep. We propose that previous conflicting findings regarding relations between LD and both psychopathology and well-being, stem from the non-differentiated assessment of frequency and control. The present study aimed to develop an expansive measure of several LD characteristics (the Frequency and Intensity Lucid Dream questionnaire; FILD), and explore their relations with symptomatology. Undergraduate students (N = 187) self-reported trait LD, psychopathology (depression, anxiety, obsessive-compulsive symptoms, dissociation, and schizotypy), stress, and sleep problems; 2 months later, a subsample (n = 78) reported psychopathology again, and also completed a dream diary each morning for 14 days. Preliminary evidence supports the reliability and validity of the FILD. Items converged into four domains: frequency, intensity (e.g., control, activity, certainty of dreaming), emotional valence, and the use of induction techniques. We report an optimal frequency cutoff score to identify those likely to experience LD within a 2-week period. Whereas LD frequency was unrelated to psychopathology, LD intensity, and positive LD emotions, were inversely associated with several psychopathological symptoms. Use of deliberate induction techniques was positively associated with psychopathology and sleep problems. Additionally, we demonstrated directionality by employing a prospective-longitudinal design, showing that deliberate LD induction predicted an increase in dissociation and

  10. Predicting Statistical Distributions of Footbridge Vibrations

    DEFF Research Database (Denmark)

    Pedersen, Lars; Frier, Christian

    2009-01-01

    The paper considers vibration response of footbridges to pedestrian loading. Employing Newmark and Monte Carlo simulation methods, a statistical distribution of bridge vibration levels is calculated modelling walking parameters such as step frequency and stride length as random variables...

  11. Magnitude of Neck-Surface Vibration as an Estimate of Subglottal Pressure during Modulations of Vocal Effort and Intensity in Healthy Speakers

    Science.gov (United States)

    McKenna, Victoria S.; Llico, Andres F.; Mehta, Daryush D.; Perkell, Joseph S.; Stepp, Cara E.

    2017-01-01

    Purpose: This study examined the relationship between the magnitude of neck-surface vibration (NSV[subscript Mag]; transduced with an accelerometer) and intraoral estimates of subglottal pressure (P'[subscript sg]) during variations in vocal effort at 3 intensity levels. Method: Twelve vocally healthy adults produced strings of /p?/ syllables in 3…

  12. Linear response properties required to simulate vibrational spectra of biomolecules in various media: (R)-phenyloxirane (A comparative theoretical and spectroscopic vibrational study)

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Jürgensen, Vibeke Würtz; Degtyarenko, I.M.

    2005-01-01

    We here present a combined VA, VCD, Raman and ROA vibrational study of phenyloxirane. We have simulated the vibrational absorption (VA), also called IR, vibrational circular dichroism (VCD), Raman scattering and Raman optical activity (ROA) intensities utilizing the density functional theory (DFT...

  13. Monitoring of vibrating machinery using artificial neural networks

    International Nuclear Information System (INIS)

    Alguindigue, I.E.; Loskiewicz-Buczak, A.

    1991-01-01

    The primary source of vibration in complex engineering systems is rotating machinery. Vibration signatures collected from these components render valuable information about the operational state of the system and may be used to perform diagnostics. For example, the low frequency domain contains information about unbalance, misalignment, instability in journal bearing and mechanical looseness; analysis of the medium frequency range can render information about faults in meshing gear teeth; while the high frequency domain will contain information about incipient faults in rolling-element bearings. Trend analysis may be performed by comparing the vibration spectrum for each machine with a reference spectrum and evaluating the vibration magnitude changes at different frequencies. This form of analysis for diagnostics is often performed by maintenance personnel monitoring and recording transducer signals and analyzing the signals to identify the operating condition of the machine. With the advent of portable fast Fourier transform (FFT) analyzers and ''laptop'' computers, it is possible to collect and analyze vibration data an site and detect incipient failures several weeks or months before repair is necessary. It is often possible to estimate the remaining life of certain systems once a fault has been detected. RMS velocity, acceleration, displacements, peak value, and crest factor readings can be collected from vibration sensors. To exploit all the information embedded in these signals, a robust and advanced analysis technique is required. Our goal is to design a diagnostic system using neural network technology, a system such as this would automate the interpretation of vibration data coming from plant-wide machinery and permit efficient on-line monitoring of these components

  14. Combined effect of whole-body vibration and ambient lighting on human discomfort, heart rate, and reaction time.

    Science.gov (United States)

    Monazzam, Mohammad Reza; Shoja, Esmaeil; Zakerian, Seyed Abolfazl; Foroushani, Abbas Rahimi; Shoja, Mohsen; Gharaee, Masoumeh; Asgari, Amin

    2018-03-12

    This study aimed to investigate the effect of whole-body vibration and ambient lighting, as well as their combined effect on human discomfort, heart rate, and reaction time in laboratory conditions. 44 men were recruited with an average age of 25.4 ± 1.9 years. Each participant was subjected to 12 experimental steps, each step lasting five minutes for four different vibration accelerations in X, Y, and Z axes at a fixed frequency; three different lighting intensities of 50, 500, and 1000 lx were also considered. At each step, a visual computerized reaction test was taken from subjects and their heart rate recorded by pulse oximeter. In addition, the discomfort rate of subjects was measured using Borg scale. Increasing vibration acceleration significantly increased the discomfort rate and heart beat but not the reaction time. Lack of lighting caused more discomfort in the subjects, but there was no significant correlation between lighting intensity with heart rate and reaction time. The results also showed that the combined effect of vibration and lighting had no significant effect on any of the discomfort, heart rate, and reaction time variables. Whole-body vibration is an important factor in the development of human subjective and physiological reactions compared to lighting. Therefore, consideration of the level of vibration to which an individual is exposed in workplaces subject to vibration plays an important role in reducing the level of human discomfort, but its interaction with ambient lighting does not have a significant effect on human subjective and physiological responses.

  15. Neuropathic pain-like alterations in muscle nociceptor function associated with vibration-induced muscle pain.

    Science.gov (United States)

    Chen, Xiaojie; Green, Paul G; Levine, Jon D

    2010-11-01

    We recently developed a rodent model of the painful muscle disorders induced by occupational exposure to vibration. In the present study we used this model to evaluate the function of sensory neurons innervating the vibration-exposed gastrocnemius muscle. Activity of 74 vibration-exposed and 40 control nociceptors, with mechanical receptive fields in the gastrocnemius muscle, were recorded. In vibration-exposed rats ∼15% of nociceptors demonstrated an intense and long-lasting barrage of action potentials in response to sustained suprathreshold mechanical stimulation (average of 2635 action potentials with frequency of ∼44Hz during a 1min suprathreshold stimulus) much greater than that has been reported to be produced even by potent inflammatory mediators. While these high-firing nociceptors had lower mechanical thresholds than the remaining nociceptors, exposure to vibration had no effect on conduction velocity and did not induce spontaneous activity. Hyperactivity was not observed in any of 19 neurons from vibration-exposed rats pretreated with intrathecal antisense for the IL-6 receptor subunit gp130. Since vibration can injure peripheral nerves and IL-6 has been implicated in painful peripheral neuropathies, we suggest that the dramatic change in sensory neuron function and development of muscles pain, induced by exposure to vibration, reflects a neuropathic muscle pain syndrome. Copyright © 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

  16. Mechanism of bubble detachment from vibrating walls

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dongjun; Park, Jun Kwon, E-mail: junkeun@postech.ac.kr; Kang, Kwan Hyoung [Department of Mechanical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of); Kang, In Seok [Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), San 31, Hyoja-dong, Pohang 790-784 (Korea, Republic of)

    2013-11-15

    We discovered a previously unobserved mechanism by which air bubbles detach from vibrating walls in glasses containing water. Chaotic oscillation and subsequent water jets appeared when a wall vibrated at greater than a critical level. Wave forms were developed at water-air interface of the bubble by the wall vibration, and water jets were formed when sufficiently grown wave-curvatures were collapsing. Droplets were pinched off from the tip of jets and fell to the surface of the glass. When the solid-air interface at the bubble-wall attachment point was completely covered with water, the bubble detached from the wall. The water jets were mainly generated by subharmonic waves and were generated most vigorously when the wall vibrated at the volume resonant frequency of the bubble. Bubbles of specific size can be removed by adjusting the frequency of the wall's vibration.

  17. Sum Frequency Generation Vibrational Spectroscopy and Kinetic Study of 2-Methylfuran and 2,5-Dimethylfuran Hydrogenation over 7 nm Platinum Cubic Nanoparticles

    KAUST Repository

    Aliaga, Cesar; Tsung, Chia-Kuang; Alayoglu, Selim; Komvopoulos, Kyriakos; Yang, Peidong; Somorjai, Gabor A.

    2011-01-01

    Sum frequency generation vibrational spectroscopy and kinetic measurements obtained from gas chromatography were used to study the adsorption and hydrogenation of 2-methylfuran (MF) and 2,5-dimethylfuran (DMF) over cubic Pt nanoparticles of 7 nm

  18. Environmental vibration reduction utilizing an array of mass scatterers

    DEFF Research Database (Denmark)

    Peplow, Andrew; Andersen, Lars Vabbersgaard; Bucinskas, Paulius

    2017-01-01

    .g. concrete or stone blocks, specially designed brick walls, etc.). The natural frequencies of vibration for such blocks depend on the local ground stiffness and on the mass of the blocks which can be chosen to provide resonance at specified frequencies. This work concerns the effectiveness of such “blocking......Ground vibration generated by rail and road traffic is a major source of environmental noise and vibration pollution in the low-frequency range. A promising and cost effective mitigation method can be the use of heavy masses placed as a periodic array on the ground surface near the road or track (e...

  19. Frequency of candidemias in a tertiary care intensive care unit

    International Nuclear Information System (INIS)

    Yaqub, K.M.; Usman, J.; Zaidi, S.B.H.; Khalil, A.; Noor, N.; Gill, M.M.

    2013-01-01

    Objective: To determine the frequency of fungal infections in intensive care unit (ICU) of Military Hospital, Rawalpindi, a tertiary care health facility. Study Design: Cross sectional study. Place and Duration of Study: Intensive Care Department of Military Hospital Rawalpindi from 01 Jan 2012 to 30 Jun 2012. Methodology: A total of 89 patients were screened with stay of more than 5 days in intensive care unit. Thirty cases were enrolled in the study for investigation of fungal infections that had fever even after 05 days of being on broad spectrum antibiotics. Culture was done on blood, urine and catheter tip samples as per clinical condition of a patient. Results: Candida infection was found in 23.4% of study cases. The mean age of study patients was 41.2 +- 20.0 years while 63.4% were female patients as compared to 36.7% males. Conclusion: Fungal infections especially candidemias are quite frequent in the intensive care units. (author)

  20. Experimental Study on the Measurement of Water Bottom Vibration Induced by Underwater Drilling Blasting

    Directory of Open Access Journals (Sweden)

    Gu Wenbin

    2015-01-01

    Full Text Available Due to the lack of proper instrumentations and the difficulties in underwater measurements, the studies about water bottom vibration induced by underwater drilling blasting are seldom reported. In order to investigate the propagation and attenuation laws of blasting induced water bottom vibration, a water bottom vibration monitor was developed with consideration of the difficulties in underwater measurements. By means of this equipment, the actual water bottom vibration induced by underwater drilling blasting was measured in a field experiment. It shows that the water bottom vibration monitor could collect vibration signals quite effectively in underwater environments. The followed signal analysis shows that the characteristics of water bottom vibration and land ground vibration induced by the same underwater drilling blasting are quite different due to the different geological environments. The amplitude and frequency band of water bottom vibration both exceed those of land ground vibration. Water bottom vibration is mainly in low-frequency band that induced by blasting impact directly acts on rock. Besides the low-frequency component, land vibration contains another higher frequency band component that induced by followed water hammer wave acts on bank slope.

  1. Structure and vibrational spectra of melaminium bis(trifluoroacetate) trihydrate: FT-IR, FT-Raman and quantum chemical calculations

    Science.gov (United States)

    Sangeetha, V.; Govindarajan, M.; Kanagathara, N.; Marchewka, M. K.; Gunasekaran, S.; Anbalagan, G.

    Melaminium bis(trifluoroacetate) trihydrate (MTFA), an organic material has been synthesized and single crystals of MTFA have been grown by the slow solvent evaporation method at room temperature. X-ray powder diffraction analysis confirms that MTFA crystal belongs to the monoclinic system with space group P2/c. The molecular geometry, vibrational frequencies and intensity of the vibrational bands have been interpreted with the aid of structure optimization based on density functional theory (DFT) B3LYP method with 6-311G(d,p) and 6-311++G(d,p) basis sets. The X-ray diffraction data have been compared with the data of optimized molecular structure. The theoretical results show that the crystal structure can be reproduced by optimized geometry and the vibrational frequencies show good agreement with the experimental values. The nuclear magnetic resonance (NMR) chemical shift of the molecule has been calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results. HOMO-LUMO, and other related molecular and electronic properties are calculated. The Mulliken and NBO charges have also been calculated and interpreted.

  2. Broadband Vibration Attenuation Using Hybrid Periodic Rods

    Directory of Open Access Journals (Sweden)

    S. Asiri

    2008-12-01

    Full Text Available This paper presents both theoretically and experimentally a new kind of a broadband vibration isolator. It is a table-like system formed by four parallel hybrid periodic rods connected between two plates. The rods consist of an assembly of periodic cells, each cell being composed of a short rod and piezoelectric inserts. By actively controlling the piezoelectric elements, it is shown that the periodic rods can efficiently attenuate the propagation of vibration from the upper plate to the lower one within critical frequency bands and consequently minimize the effects of transmission of undesirable vibration and sound radiation. In such a system, longitudinal waves can propagate from the vibration source in the upper plate to the lower one along the rods only within specific frequency bands called the "Pass Bands" and wave propagation is efficiently attenuated within other frequency bands called the "Stop Bands". The spectral width of these bands can be tuned according to the nature of the external excitation. The theory governing the operation of this class of vibration isolator is presented and their tunable filtering characteristics are demonstrated experimentally as functions of their design parameters. This concept can be employed in many applications to control the wave propagation and the force transmission of longitudinal vibrations both in the spectral and spatial domains in an attempt to stop/attenuate the propagation of undesirable disturbances.

  3. Vibrational spectra of aminoacetonitrile

    International Nuclear Information System (INIS)

    Bak, B.; Hansen, E.L.; Nicolaisen, F.M.; Nielsen, O.F.

    1975-01-01

    The preparation of pure, stable aminoacetonitrile(1-amino, 1'-cyanomethane)CH 2 NH 2 CN (1) is described. The Raman spectrum, now complete, and a novel infrared spectrum extending over the 50-3600 cm -1 region are reported. A tentative normal vibration analysis is presented and supported by Raman and infrared data from the spectra of CH 2 NHDCN (2) and CH 2 ND 2 CN (3). The predominance of the trans rotamer may be attributed to intramolecular hydrogen bonding but this is too unimportant to influence the vibrational frequencies of gaseous 1, 2, and 3. However, large gas/liquid frequency shifts occur. (author)

  4. Frequency conversion of high-intensity, femtosecond laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Banks, P S

    1997-06-01

    Almost since the invention of the laser, frequency conversion of optical pulses via non- linear processes has been an area of active interest. However, third harmonic generation using ~(~1 (THG) in solids is an area that has not received much attention because of ma- terial damage limits. Recently, the short, high-intensity pulses possible with chirped-pulse amplification (CPA) laser systems allow the use of intensities on the order of 1 TW/cm2 in thin solids without damage. As a light source to examine single-crystal THG in solids and other high field inter- actions, the design and construction of a Ti:sapphire-based CPA laser system capable of ultimately producing peak powers of 100 TW is presented. Of special interest is a novel, all-reflective pulse stretcher design which can stretch a pulse temporally by a factor of 20,000. The stretcher design can also compensate for the added material dispersion due to propagation through the amplifier chain and produce transform-limited 45 fs pulses upon compression. A series of laser-pumped amplifiers brings the peak power up to the terawatt level at 10 Hz, and the design calls for additional amplifiers to bring the power level to the 100 TW level for single shot operation. The theory for frequency conversion of these short pulses is presented, focusing on conversion to the third harmonic in single crystals of BBO, KD*P, and d-LAP (deuterated I-arginine phosphate). Conversion efficiencies of up to 6% are obtained with 500 fs pulses at 1053 nm in a 3 mm thick BBO crystal at 200 GW/cm 2. Contributions to this process by unphasematched, cascaded second harmonic generation and sum frequency generation are shown to be very significant. The angular relationship between the two orders is used to measure the tensor elements of C = xt3)/4 with Crs = -1.8 x 1O-23 m2/V2 and .15Cri + .54Crs = 4.0 x 1O-23 m2/V2. Conversion efficiency in d-LAP is about 20% that in BBO and conversion efficiency in KD*P is 1% that of BBO. It is calculated

  5. Gray bootstrap method for estimating frequency-varying random vibration signals with small samples

    Directory of Open Access Journals (Sweden)

    Wang Yanqing

    2014-04-01

    Full Text Available During environment testing, the estimation of random vibration signals (RVS is an important technique for the airborne platform safety and reliability. However, the available methods including extreme value envelope method (EVEM, statistical tolerances method (STM and improved statistical tolerance method (ISTM require large samples and typical probability distribution. Moreover, the frequency-varying characteristic of RVS is usually not taken into account. Gray bootstrap method (GBM is proposed to solve the problem of estimating frequency-varying RVS with small samples. Firstly, the estimated indexes are obtained including the estimated interval, the estimated uncertainty, the estimated value, the estimated error and estimated reliability. In addition, GBM is applied to estimating the single flight testing of certain aircraft. At last, in order to evaluate the estimated performance, GBM is compared with bootstrap method (BM and gray method (GM in testing analysis. The result shows that GBM has superiority for estimating dynamic signals with small samples and estimated reliability is proved to be 100% at the given confidence level.

  6. Intrinsic Chirality and Prochirality at Air/R-(+)- and S-(-)-Limonene Interfaces: Spectral Signatures with Interference Chiral Sum-Frequency Generation Vibrational Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Li; Zhang, Yun; Wei, Zhehao; Wang, Hongfei

    2014-06-04

    We report in this work detailed measurements on the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050cm-1) of the air/liquid interfaces of R-limonene and S-limonene, using the recently developed high-resolution broadband sum-frequency generation vibrational spectroscopy (HR-BB-SFG-VS). The achiral SFG spectra of R-limonene and S-limonene, as well as the equal amount (50/50) racemic mixture show that the enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit spectral signature from chiral response of the Cα-H stretching mode, and spectral signature from prochiral response of the CH2 asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-limonene to S-limonene, and disappears for the 50/50 racemic mixture. While the prochiral spectral feature of the CH2 asymmetric stretching mode is the same for R-limonene and S-limonene, and also surprisingly remains the same for the 50/50 racemic mixture. These results provided detail information in understanding the structure and chirality of molecular interfaces, and demonstrated the sensitivity and potential of SFG-VS as unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface.

  7. Low-Frequency MEMS Electrostatic Vibration Energy Harvester With Corona-Charged Vertical Electrets and Nonlinear Stoppers

    Science.gov (United States)

    Lu, Y.; Cottone, F.; Boisseau, S.; Galayko, D.; Marty, F.; Basset, P.

    2015-12-01

    This paper reports for the first time a MEMS electrostatic vibration energy harvester (e-VEH) with corona-charged vertical electrets on its electrodes. The bandwidth of the 1-cm2 device is extended in low and high frequencies by nonlinear elastic stoppers. With a bias voltage of 46 V (electret@21 V + DC external source@25 V) between the electrodes, the RMS power of the device reaches 0.89 μW at 33 Hz and 6.6 μW at 428 Hz. The -3dB frequency band including the hysteresis is 223∼432 Hz, the one excluding the hysteresis 88∼166 Hz. We also demonstrate the charging of a 47 μF capacitor used for powering a wireless and autonomous temperature sensor node with a data transmission beyond 10 m at 868 MHz.

  8. Theoretical rotation-vibration spectrum of thioformaldehyde

    International Nuclear Information System (INIS)

    Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter

    2013-01-01

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H 2 CS. It covers 41 809 rovibrational levels for states up to J max = 30 with vibrational band origins up to 5000 cm −1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments

  9. Theoretical rotation-vibration spectrum of thioformaldehyde

    Science.gov (United States)

    Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter

    2013-11-01

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H2CS. It covers 41 809 rovibrational levels for states up to Jmax = 30 with vibrational band origins up to 5000 cm-1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments.

  10. Theoretical rotation-vibration spectrum of thioformaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Yachmenev, Andrey [Department of Physics and Astronomy, University College London, London, WC1E 6BT (United Kingdom); Polyak, Iakov; Thiel, Walter [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D–45470 Mülheim an der Ruhr (Germany)

    2013-11-28

    We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H{sub 2}CS. It covers 41 809 rovibrational levels for states up to J{sub max} = 30 with vibrational band origins up to 5000 cm{sup −1} and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments.

  11. A study on the evaluation of vibration effect and the development of vibration reduction method for Wolsung unit 1 main steam piping

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyun; Kim, Yeon Whan [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Tae Ryong; Park, Jin Ho [Korea Atomic Energy Research Inst., Daeduk (Korea, Republic of)

    1996-08-01

    The main steam piping of nuclear power plant which runs between steam generator and high pressure turbine has been experienced to have a severe effect on the safe operation of the plant due to the vibration induced by the steam flowing inside the piping. The imposed cyclic loads by the vibration could result in the degradation of the related structures such as connection parts between main instruments, valves, pipe supports and building. The objective of the study is to reduce the vibration level of Wolsung nuclear power plant unit 1 main steam pipeline by analyzing vibration characteristics of the piping, identifying sources of the vibration and developing a vibration reduction method .The location of the maximum vibration is piping between the main steam header and steam chest .The stress level was found to be within the allowable limit .The main vibration frequency was found to be 4{approx}6 Hz which is the same as the natural frequency from model test .A vibration reduction method using pipe supports of energy absorbing type(WEAR)is selected .The measured vibration level after WEAR installation was reduced about 36{approx}77% in displacement unit (author). 36 refs., 188 figs.

  12. Experimental research on pressure fluctuation and vibration in a mixed flow pump

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Kai; Liu, Houlin; Wang, Wenbo [National Research Center of Pumps and Pumping System Engineering and Technology, Jiangsu University, Zhenjiang (China); Zhou, Xiaohua [Gree Electric Appliance Inc. of Zhuhai, Zhuhai (China)

    2016-01-15

    To study the pressure fluctuation and vibration in mixed flow pumps, we chose a mixed flow pump with specific speed of 436.1 to measure. The time domains and frequency domain at each monitoring point on diffuser and outlet elbow were analyzed, as well as the vibration frequency domain characteristics at the impeller outlet and near the motor. The results show that the peak value of pressure fluctuation peak decreased gradually with the increase of flow rate. The pressure fluctuation of each monitoring point had periodicity, and the frequency domain dominated by blade passing frequency and multiple shaft frequency. The vibration frequency of each monitoring point occurred at shaft frequency and its multiple shaft frequency. The dominant frequency and the second frequency were distributed in shaft frequency and double shaft frequency.

  13. The impact of low-magnitude high-frequency vibration on fracture healing is profoundly influenced by the oestrogen status in mice.

    Science.gov (United States)

    Wehrle, Esther; Liedert, Astrid; Heilmann, Aline; Wehner, Tim; Bindl, Ronny; Fischer, Lena; Haffner-Luntzer, Melanie; Jakob, Franz; Schinke, Thorsten; Amling, Michael; Ignatius, Anita

    2015-01-01

    Fracture healing is impaired in aged and osteoporotic individuals. Because adequate mechanical stimuli are able to increase bone formation, one therapeutical approach to treat poorly healing fractures could be the application of whole-body vibration, including low-magnitude high-frequency vibration (LMHFV). We investigated the effects of LMHFV on fracture healing in aged osteoporotic mice. Female C57BL/6NCrl mice (n=96) were either ovariectomised (OVX) or sham operated (non-OVX) at age 41 weeks. When aged to 49 weeks, all mice received a femur osteotomy that was stabilised using an external fixator. The mice received whole-body vibrations (20 minutes/day) with 0.3 G: peak-to-peak acceleration and a frequency of 45 Hz. After 10 and 21 days, the osteotomised femurs and intact bones (contra-lateral femurs, lumbar spine) were evaluated using bending-testing, micro-computed tomography (μCT), histology and gene expression analyses. LMHFV disturbed fracture healing in aged non-OVX mice, with significantly reduced flexural rigidity (-81%) and bone formation (-80%) in the callus. Gene expression analyses demonstrated increased oestrogen receptor β (ERβ, encoded by Esr2) and Sost expression in the callus of the vibrated animals, but decreased β-catenin, suggesting that ERβ might mediate these negative effects through inhibition of osteoanabolic Wnt/β-catenin signalling. In contrast, in OVX mice, LMHFV significantly improved callus properties, with increased flexural rigidity (+1398%) and bone formation (+637%), which could be abolished by subcutaneous oestrogen application (0.025 mg oestrogen administered in a 90-day-release pellet). On a molecular level, we found an upregulation of ERα in the callus of the vibrated OVX mice, whereas ERβ was unaffected, indicating that ERα might mediate the osteoanabolic response. Our results indicate a major role for oestrogen in the mechanostimulation of fracture healing and imply that LMHFV might only be safe and effective in

  14. The impact of low-magnitude high-frequency vibration on fracture healing is profoundly influenced by the oestrogen status in mice

    Directory of Open Access Journals (Sweden)

    Esther Wehrle

    2015-01-01

    Full Text Available Fracture healing is impaired in aged and osteoporotic individuals. Because adequate mechanical stimuli are able to increase bone formation, one therapeutical approach to treat poorly healing fractures could be the application of whole-body vibration, including low-magnitude high-frequency vibration (LMHFV. We investigated the effects of LMHFV on fracture healing in aged osteoporotic mice. Female C57BL/6NCrl mice (n=96 were either ovariectomised (OVX or sham operated (non-OVX at age 41 weeks. When aged to 49 weeks, all mice received a femur osteotomy that was stabilised using an external fixator. The mice received whole-body vibrations (20 minutes/day with 0.3 g peak-to-peak acceleration and a frequency of 45 Hz. After 10 and 21 days, the osteotomised femurs and intact bones (contra-lateral femurs, lumbar spine were evaluated using bending-testing, micro-computed tomography (μCT, histology and gene expression analyses. LMHFV disturbed fracture healing in aged non-OVX mice, with significantly reduced flexural rigidity (−81% and bone formation (−80% in the callus. Gene expression analyses demonstrated increased oestrogen receptor β (ERβ, encoded by Esr2 and Sost expression in the callus of the vibrated animals, but decreased β-catenin, suggesting that ERβ might mediate these negative effects through inhibition of osteoanabolic Wnt/β-catenin signalling. In contrast, in OVX mice, LMHFV significantly improved callus properties, with increased flexural rigidity (+1398% and bone formation (+637%, which could be abolished by subcutaneous oestrogen application (0.025 mg oestrogen administered in a 90-day-release pellet. On a molecular level, we found an upregulation of ERα in the callus of the vibrated OVX mice, whereas ERβ was unaffected, indicating that ERα might mediate the osteoanabolic response. Our results indicate a major role for oestrogen in the mechanostimulation of fracture healing and imply that LMHFV might only be safe and

  15. Prestress Force Identification for Externally Prestressed Concrete Beam Based on Frequency Equation and Measured Frequencies

    Directory of Open Access Journals (Sweden)

    Luning Shi

    2014-01-01

    Full Text Available A prestress force identification method for externally prestressed concrete uniform beam based on the frequency equation and the measured frequencies is developed. For the purpose of the prestress force identification accuracy, we first look for the appropriate method to solve the free vibration equation of externally prestressed concrete beam and then combine the measured frequencies with frequency equation to identify the prestress force. To obtain the exact solution of the free vibration equation of multispan externally prestressed concrete beam, an analytical model of externally prestressed concrete beam is set up based on the Bernoulli-Euler beam theory and the function relation between prestress variation and vibration displacement is built. The multispan externally prestressed concrete beam is taken as the multiple single-span beams which must meet the bending moment and rotation angle boundary conditions, the free vibration equation is solved using sublevel simultaneous method and the semi-analytical solution of the free vibration equation which considered the influence of prestress on section rigidity and beam length is obtained. Taking simply supported concrete beam and two-span concrete beam with external tendons as examples, frequency function curves are obtained with the measured frequencies into it and the prestress force can be identified using the abscissa of the crosspoint of frequency functions. Identification value of the prestress force is in good agreement with the test results. The method can accurately identify prestress force of externally prestressed concrete beam and trace the trend of effective prestress force.

  16. The region of influence of significant defects and the mechanical vibrations of linear elastic solids

    International Nuclear Information System (INIS)

    Suarez Antola, R.

    2004-12-01

    The presence of cracks, voids or fields of pores, and their growth under applied forces or environmental actions, can produce a meaningful lowering in the proper frequencies of normal modes of mechanical vibration in machines and structures. A quite general expression for the square of modes proper frequency as a functional of displacement field, density field and elastic moduli fields is used as a starting point. The effect of defects on frequency are modeled as equivalent changes in density and elastic moduli fields, introducing the concept of region of influence of each defect. This region of influence is derived from the relation between the stress field of flawed components in machines or structures, and the elastic energy released from a suitable reference state, due to the presence of significant defects in the above mentioned mechanical components. An approximate analytical expression is obtained, which relates the relative variation in the square of mode s proper frequency with position, size, shape and orientation of defects in mode displacement field. Some simple mathematical models of machine and structural elements with cracks or fields of pores are considered as examples. The connections between the relative lowering in the square of mode s proper frequency and the stress intensity factor of a defect are discussed : the concept of region of influence of a defect is used as a bridge between (low frequency and low amplitude) vibration dynamics and linear elastic fracture mechanics. Some limitations of the present approach are discussed as well as the possibility of applying the region of influence of defects to the damping of normal modes of vibration

  17. Demonstration of Vibrational Braille Code Display Using Large Displacement Micro-Electro-Mechanical Systems Actuators

    Science.gov (United States)

    Watanabe, Junpei; Ishikawa, Hiroaki; Arouette, Xavier; Matsumoto, Yasuaki; Miki, Norihisa

    2012-06-01

    In this paper, we present a vibrational Braille code display with large-displacement micro-electro-mechanical systems (MEMS) actuator arrays. Tactile receptors are more sensitive to vibrational stimuli than to static ones. Therefore, when each cell of the Braille code vibrates at optimal frequencies, subjects can recognize the codes more efficiently. We fabricated a vibrational Braille code display that used actuators consisting of piezoelectric actuators and a hydraulic displacement amplification mechanism (HDAM) as cells. The HDAM that encapsulated incompressible liquids in microchambers with two flexible polymer membranes could amplify the displacement of the MEMS actuator. We investigated the voltage required for subjects to recognize Braille codes when each cell, i.e., the large-displacement MEMS actuator, vibrated at various frequencies. Lower voltages were required at vibration frequencies higher than 50 Hz than at vibration frequencies lower than 50 Hz, which verified that the proposed vibrational Braille code display is efficient by successfully exploiting the characteristics of human tactile receptors.

  18. Free vibration analysis of corroded steel plates

    Energy Technology Data Exchange (ETDEWEB)

    Eslami-Majd, Alireza; Rahbar-Ranji, Ahmad [AmirKabir University of Technology, Tehran (Iran, Islamic Republic of)

    2014-06-15

    Vibration analysis of unstiffened/stiffened plates has long been studied due to its importance in the design and condition assessments of ship and offshore structures. Corrosion is inevitable in steel structures and has been so far considered in strength analysis of structures. We studied the free vibration of pitted corroded plates with simply supported boundary conditions. Finite element analysis, with ABAQUS, was used to determine the natural frequencies and mode shapes of corroded plates. Influential parameters including plate aspect ratio, degree of pit, one-sided/both-sided corroded plate, and different corrosion patterns were investigated. By increasing the degree of corrosion, reduction of natural frequency increases. Plate aspect ratio and plate dimensions have no influence on reduction of natural frequency. Different corrosion patterns on the surface of one-sided corroded plates have little influence on reduction of natural frequency. Ratio of pit depth over plate thickness has no influence on the reduction of natural frequency. The reduction of natural frequency in both-sided corroded plates is higher than one-sided corroded plates with the same amount of total corrosion loss. Mode shapes of vibration would change due to corrosion, except square mode shapes.

  19. Probabilistic Rainfall Intensity-Duration-Frequency Curves for the October 2015 Flooding in South Carolina

    Science.gov (United States)

    Phillips, R.; Samadi, S. Z.; Meadows, M.

    2017-12-01

    The potential for the intensity of extreme rainfall to increase with climate change nonstationarity has emerged as a prevailing issue for the design of engineering infrastructure, underscoring the need to better characterize the statistical assumptions underlying hydrological frequency analysis. The focus of this study is on developing probabilistic rainfall intensity-duration-frequency (IDF) curves for the major catchments in South Carolina (SC) where the October 02-05, 2015 floods caused infrastructure damages and several lives to be lost. Continuous to discrete probability distributions including Weibull, the generalized extreme value (GEV), the Generalized Pareto (GP), the Gumbel, the Fréchet, the normal, and the log-normal functions were fitted to the short duration (i.e., 24-hr) intense rainfall. Analysis suggests that the GEV probability distribution provided the most adequate fit to rainfall records. Rainfall frequency analysis indicated return periods above 500 years for urban drainage systems with a maximum return level of approximately 2,744 years, whereas rainfall magnitude was much lower in rural catchments. Further, the return levels (i.e., 2, 20, 50,100, 500, and 1000 years) computed by Monte Carlo method were consistently higher than the NOAA design IDF curves. Given the potential increase in the magnitude of intense rainfall, current IDF curves can substantially underestimate the frequency of extremes, indicating the susceptibility of the storm drainage and flood control structures in SC that were designed under assumptions of a stationary climate.

  20. Prototype observation and influencing factors of environmental vibration induced by flood discharge

    Directory of Open Access Journals (Sweden)

    Xin Wang

    2017-01-01

    Full Text Available Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The results indicate that field vibrations caused by flood discharge have distinctive characteristics of constancy, low frequency, small amplitude, and randomness with impact, which significantly differ from the common high-frequency vibration characteristics. Field vibrations have a main frequency of about 0.5–3.0 Hz and the characteristics of long propagation distance and large-scale impact. The vibration of a stilling basin slab runs mainly in the vertical direction. The vibration response of the guide wall perpendicular to the flow is significantly stronger than it is in other directions and decreases linearly downstream along the guide wall. The vibration response of the underground turbine floor is mainly caused by the load of unit operation. Urban environmental vibration has particular distribution characteristics and change patterns, and is greatly affected by discharge, scheduling modes, and geological conditions. Along with the increase of the height of residential buildings, vibration responses show a significant amplification effect. The horizontal and vertical vibrations of the 7th floor are, respectively, about 6 times and 1.5 times stronger than the corresponding vibrations of the 1st floor. The vibration of a large-scale chemical plant presents the combined action of flood discharge and working machines. Meanwhile, it is very difficult to reduce the low-frequency environmental vibrations. Optimization of the discharge scheduling mode is one of the effective measures of reducing the flow impact loads at present. Choosing reasonable dam sites is crucial.

  1. Vibrational relaxation dynamics of SD molecules in As2S3: Observation of an anomalous isotope effect

    International Nuclear Information System (INIS)

    Engholm, J.R.; Happek, U.; Rella, C.W.

    1995-01-01

    It is generally assumed that the vibrational relaxation of molecular impurities in crystals and glasses mainly depends on the order of the decay process, with lower order processes leading to more rapid relaxation (a behavior that is known under the term open-quotes gap-lawclose quotes). Here we present measurements that contradict this assumption. Using high intensity psec pulses of the Stanford FEL we measured the relaxation rate of the SD vibrational stretch mode (at a frequency of 1800 cm) by applying a pump-probe technique. We find relaxation rates on the order of 2x10 9 sec -1 , which are a factor of 2 lower than those found for the isotope molecule SH (at a frequency of about 2500 cm - 1 ) in the same host 1 . We recall that the relaxation of the SD vibrational stretch mode is controlled by a lower order process as compared to the SH molecule, which is due to the smaller number of host vibrational quanta to match the energy of the stretch mode; a fact we have confirmed experimentally by temperature dependent relaxation measurements. Thus our remits are in marked contrast to the so-called open-quotes Gap-Lawclose quotes and emphasize the importance of the molecule - host coupling in the relaxation dynamics

  2. Application of vibration to wrist and hand skin affects fingertip tactile sensation

    Science.gov (United States)

    Lakshminarayanan, Kishor; Lauer, Abigail W; Ramakrishnan, Viswanathan; Webster, John G; Seo, Na Jin

    2015-01-01

    A recent study showed that fingertip pads’ tactile sensation can improve by applying imperceptible white-noise vibration to the skin at the wrist or dorsum of the hand in stroke patients. This study further examined this behavior by investigating the effect of both imperceptible and perceptible white-noise vibration applied to different locations within the distal upper extremity on the fingertip pads’ tactile sensation in healthy adults. In 12 healthy adults, white-noise vibration was applied to one of four locations (dorsum hand by the second knuckle, thenar and hypothenar areas, and volar wrist) at one of four intensities (zero, 60%, 80%, and 120% of the sensory threshold for each vibration location), while the fingertip sensation, the smallest vibratory signal that could be perceived on the thumb and index fingertip pads, was assessed. Vibration intensities significantly affected the fingertip sensation (P sensation (P sensation (P sensation (P > 0.01), all compared with the zero vibration condition. This effect with vibration intensity conforms to the stochastic resonance behavior. Nonspecificity to the vibration location suggests the white-noise vibration affects higher level neuronal processing for fingertip sensing. Further studies are needed to elucidate the neural pathways for distal upper extremity vibration to impact fingertip pad tactile sensation. PMID:26177959

  3. Assessment of vibration anomalies of main steam lines at Palo Verde-3

    International Nuclear Information System (INIS)

    Amr, A.; Landstrom, C.; Maxwell, H.; Miller, J.S.; Lynch, J.J.

    1996-01-01

    Historically, flow induced vibration in piping systems that transport liquid has presented problems for plant designers. When evaluating a vibration problem, it is always important to determine the forcing frequencies from different phenomena and the natural frequencies of the system as an integral part of establishing the root cause of the problem. Since in most cases of large vibration and noise levels, the natural frequency of the system and the frequency of the flow induced vibration are very close, determining the natural frequency of the system is important. Palo Verde Unit-3 exhibited a vibration problem where identification of the root cause was difficult. A Palo Verde team was created which consisted of engineers from different on-site departments and support from consultants. The process used to determine the root cause for the vibration/noise problem on Main Steam Supply System (MSSS) steam line 2 at Palo Verde Unit 3 is discussed in this paper. Since the root cause was not readily apparent, a finite element model was constructed to determine the natural frequency of the piping system. The finite element model consisted of a portion of the main steam lines, including a sample line which traverses the main steam line

  4. Model Predictive Vibration Control Efficient Constrained MPC Vibration Control for Lightly Damped Mechanical Structures

    CERN Document Server

    Takács, Gergely

    2012-01-01

    Real-time model predictive controller (MPC) implementation in active vibration control (AVC) is often rendered difficult by fast sampling speeds and extensive actuator-deformation asymmetry. If the control of lightly damped mechanical structures is assumed, the region of attraction containing the set of allowable initial conditions requires a large prediction horizon, making the already computationally demanding on-line process even more complex. Model Predictive Vibration Control provides insight into the predictive control of lightly damped vibrating structures by exploring computationally efficient algorithms which are capable of low frequency vibration control with guaranteed stability and constraint feasibility. In addition to a theoretical primer on active vibration damping and model predictive control, Model Predictive Vibration Control provides a guide through the necessary steps in understanding the founding ideas of predictive control applied in AVC such as: ·         the implementation of ...

  5. Vibrational mechanics nonlinear dynamic effects, general approach, applications

    CERN Document Server

    Blekhman, Iliya I

    2000-01-01

    This important book deals with vibrational mechanics - the new, intensively developing section of nonlinear dynamics and the theory of nonlinear oscillations. It offers a general approach to the study of the effect of vibration on nonlinear mechanical systems.The book presents the mathematical apparatus of vibrational mechanics which is used to describe such nonlinear effects as the disappearance and appearance under vibration of stable positions of equilibrium and motions (i.e. attractors), the change of the rheological properties of the media, self-synchronization, self-balancing, the vibrat

  6. Vibrational Spectroscopy of Ionic Liquids.

    Science.gov (United States)

    Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C

    2017-05-24

    Vibrational spectroscopy has continued use as a powerful tool to characterize ionic liquids since the literature on room temperature molten salts experienced the rapid increase in number of publications in the 1990's. In the past years, infrared (IR) and Raman spectroscopies have provided insights on ionic interactions and the resulting liquid structure in ionic liquids. A large body of information is now available concerning vibrational spectra of ionic liquids made of many different combinations of anions and cations, but reviews on this literature are scarce. This review is an attempt at filling this gap. Some basic care needed while recording IR or Raman spectra of ionic liquids is explained. We have reviewed the conceptual basis of theoretical frameworks which have been used to interpret vibrational spectra of ionic liquids, helping the reader to distinguish the scope of application of different methods of calculation. Vibrational frequencies observed in IR and Raman spectra of ionic liquids based on different anions and cations are discussed and eventual disagreements between different sources are critically reviewed. The aim is that the reader can use this information while assigning vibrational spectra of an ionic liquid containing another particular combination of anions and cations. Different applications of IR and Raman spectroscopies are given for both pure ionic liquids and solutions. Further issues addressed in this review are the intermolecular vibrations that are more directly probed by the low-frequency range of IR and Raman spectra and the applications of vibrational spectroscopy in studying phase transitions of ionic liquids.

  7. Vibrational mode frequencies of silica species in SiO2-H2O liquids and glasses from ab initio molecular dynamics.

    Science.gov (United States)

    Spiekermann, Georg; Steele-MacInnis, Matthew; Schmidt, Christian; Jahn, Sandro

    2012-04-21

    Vibrational spectroscopy techniques are commonly used to probe the atomic-scale structure of silica species in aqueous solution and hydrous silica glasses. However, unequivocal assignment of individual spectroscopic features to specific vibrational modes is challenging. In this contribution, we establish a connection between experimentally observed vibrational bands and ab initio molecular dynamics (MD) of silica species in solution and in hydrous silica glass. Using the mode-projection approach, we decompose the vibrations of silica species into subspectra resulting from several fundamental structural subunits: The SiO(4) tetrahedron of symmetry T(d), the bridging oxygen (BO) Si-O-Si of symmetry C(2v), the geminal oxygen O-Si-O of symmetry C(2v), the individual Si-OH stretching, and the specific ethane-like symmetric stretching contribution of the H(6)Si(2)O(7) dimer. This allows us to study relevant vibrations of these subunits in any degree of polymerization, from the Q(0) monomer up to the fully polymerized Q(4) tetrahedra. Demonstrating the potential of this approach for supplementing the interpretation of experimental spectra, we compare the calculated frequencies to those extracted from experimental Raman spectra of hydrous silica glasses and silica species in aqueous solution. We discuss observed features such as the double-peaked contribution of the Q(2) tetrahedral symmetric stretch, the individual Si-OH stretching vibrations, the origin of the experimentally observed band at 970 cm(-1) and the ethane-like vibrational contribution of the H(6)Si(2)O(7) dimer at 870 cm(-1).

  8. Dispersion of low frequency vibrations in the deuterated naphthalene crystal

    International Nuclear Information System (INIS)

    Bokhenkov, E.L.; Sheka, E.; Natkaniec, I.

    1977-01-01

    The dispersion curves of the lattice vibrations and of the two lowest intramolecular vibrations in d 8 -naphthalene (C 10 D 8 ) crystal have been measured by coherent inelastic neutron scattering for the [010] and the [100] directions at the temperature of 98 K and partially at 5 K. The results are compared with calculations based on the Kitaigorodskii parameters for C-C, C-H and H-H interactions in organic molecular crystals. (author)

  9. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  10. Synchronization of vortex formation frequency with the body motion frequency at high Reynolds numbers

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Luiz Antonio Alcantara [Federal University of Itajuba (UNIFEI), MG (Brazil). Inst. of Mechanical Engineering], E-mail: luizantp@unifei.edu.br; Hirata, Miguel Hiroo [State University of Rio de Janeiro (FAT/UERJ), Resende, RJ (Brazil). Fac. de Tecnologia], E-mail: hirata@fat.uerj.br

    2010-07-01

    Understanding vortex induced vibrations is of great importance in the design of a variety of offshore engineering structures, nuclear plant components and cylindrical elements in tube-bank heat exchangers, for example. If a body is placed in a flow, it experiences alternating lift and drag forces caused by the asymmetric formation of vortices, which can cause a structure to vibrate. One of the most interesting features of this flow is the phenomenon of lock-in which is observed when the vortex shedding frequency is close to the body oscillation frequency. This paper presents the results of numerical experiments on vortex shedding from a circular cylinder vibrating in-line or transversely with an incident uniform flow at Reynolds number of 1.0 x 10{sup 5}. The frequencies of the lift and drag coefficients are compared with the body motion frequency when the frequency ratio is about unity. (author)

  11. Design of a nonlinear torsional vibration absorber

    Science.gov (United States)

    Tahir, Ammaar Bin

    Tuned mass dampers (TMD) utilizing linear spring mechanisms to mitigate destructive vibrations are commonly used in practice. A TMD is usually tuned for a specific resonant frequency or an operating frequency of a system. Recently, nonlinear vibration absorbers attracted attention of researchers due to some potential advantages they possess over the TMDs. The nonlinear vibration absorber, or the nonlinear energy sink (NES), has an advantage of being effective over a broad range of excitation frequencies, which makes it more suitable for systems with several resonant frequencies, or for a system with varying excitation frequency. Vibration dissipation mechanism in an NES is passive and ensures that there is no energy backflow to the primary system. In this study, an experimental setup of a rotational system has been designed for validation of the concept of nonlinear torsional vibration absorber with geometrically induced cubic stiffness nonlinearity. Dimensions of the primary system have been optimized so as to get the first natural frequency of the system to be fairly low. This was done in order to excite the dynamic system for torsional vibration response by the available motor. Experiments have been performed to obtain the modal parameters of the system. Based on the obtained modal parameters, the design optimization of the nonlinear torsional vibration absorber was carried out using an equivalent 2-DOF modal model. The optimality criterion was chosen to be maximization of energy dissipation in the nonlinear absorber attached to the equivalent 2-DOF system. The optimized design parameters of the nonlinear absorber were tested on the original 5-DOF system numerically. A comparison was made between the performance of linear and nonlinear absorbers using the numerical models. The comparison showed the superiority of the nonlinear absorber over its linear counterpart for the given set of primary system parameters as the vibration energy dissipation in the former is

  12. Fluid-elastic vibration in two-phase cross flow

    International Nuclear Information System (INIS)

    Sasakawa, T.; Serizawa, A.; Kawara, Z.

    2003-01-01

    The present work aims at clarifying the mechanisms of fluid elastic vibration of tube bundles in two-phase cross flow. The experiment is conducted using air-water two-phase flow under atmospheric pressure. The test section is a 1.03m long transparent acrylic square duct with 128 x 128 mm 2 cross section, which consists of 3 rod-rows with 5 rods in each row. The rods are 125mm long aluminum rods with 22 mm in diameter (p/D=1.45). The natural frequency of rod vibration is about 30Hz. The result indicated a diversion of observed trend in vibration behavior depending on two-phase flow patterns either bubbly flow or churn flow. Specifically, in churn flow, the fluid elastic vibration has been observed to occur when the frequency in void fraction fluctuation approached to the natural frequency of the rods, but this was not the case in fluid elastic vibration in bubbly flow. This fact suggests the existence of mechanisms closely coupled with two-phase flow structures depending on the flow patterns, that is, static two-phase character-controlled mechanism in bubbly flow and dynamic character- controlled in churn flow

  13. The Biological Effect of Extremely Low Frequency Electromagnetic Fields and Vibrations on Barley Seed Hydration and Germination

    Directory of Open Access Journals (Sweden)

    Armine Amyan

    2004-01-01

    Full Text Available The changes of wet and dry weights and germination of barley seed in different periods of its swelling in nontreated (control, extremely low frequency electromagnetic fields (ELF EMF –treated, and extremely low frequency vibrations (ELFV–treated cold (4°C and warm (20°C distilled water (DW were studied. The metabolic-dependent seed hydration, dry weight dissolving, germination, and water binding in seed were modulated by preliminary EMF- and ELFV-treated DW. Frequency “windows” for the effect of EMF and ELFV on seed hydration, solubility, water binding in seed, and germination were discovered. These “windows” were different for EMF and ELFV, as well as in various phases of seed swelling. It is suggested that EMF-induced water structure modification has a different biological effect on the process of seed hydration, solubility, water binding in seed, and germination compared to ELFV.

  14. Effect of low-frequency low-intensity ultrasound with microbubbles on prostate cancer hypoxia.

    Science.gov (United States)

    Hou, Rui; Xu, Yanjun; Lu, Qijie; Zhang, Yang; Hu, Bing

    2017-10-01

    Angiogenesis plays an important role in tumor growth, invasiveness, and metastasis. It is well established that prostate cancer is exposed to fluctuating oxygen tensions and both acute and chronic hypoxia exist, and these conditions can upregulate angiogenesis-associated proteins such as hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A. Low-frequency low-intensity ultrasound with microbubbles can induce obvious microvessel damage in tumors, cause cell necrosis or apoptosis. However, there is no information about whether the blocking blood effect of low-frequency low-intensity ultrasound with microbubbles has an influence on hypoxia environment of prostate cancer. Therefore, we investigated the impact of different low-frequency low-intensity ultrasound with microbubbles radiation times on prostate tumors, observed the change in the hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A protein levels, as well as cell proliferation, apoptosis, and tumor volume. The results indicated that as the radiation was repeated four times on each treatment day, the effects of interruption were durable, the cell proliferation was inhibited, and apoptosis was promoted, and the hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A expression levels were lower in the treatment group than in the control group. When the radiation was carried out once per treatment day, the hypoxia response was stimulated, the hypoxia-inducible factor 1 alpha and vascular endothelial growth factor A expression levels were higher compared with the control group, and cell proliferation was promoted. In addition, the tumor volume increased obviously in the hypoxia-stimulated group, whereas tumors grew slowly in the hypoxia-suppressed group. The results of this work demonstrated that under the same conditions, different radiation times of low-frequency low-intensity ultrasound with microbubbles affect the hypoxia response differently, and the

  15. Local vibrations and lift performance of low Reynolds number airfoil

    Directory of Open Access Journals (Sweden)

    TariqAmin Khan

    2017-06-01

    Full Text Available The 2D incompressible Navier-Stokes equations are solved based on the finite volume method and dynamic mesh technique is used to carry out partial fluid structure interaction. The local flexible structure (hereinafter termed as flexible structure vibrates in a single mode located on the upper surface of the airfoil. The Influence of vibration frequency and amplitude are examined and the corresponding fluid flow characteristics are investigated which add complexity to the inherent problem in unsteady flow. The study is conducted for flow over NACA0012 airfoil at 600≤Re≤3000 at a low angle of attack. Vibration of flexible structure induces a secondary vortex which modifies the pressure distribution and lift performance of the airfoil. At some moderate vibration amplitude, frequency synchronization or lock-in phenomenon occurs when the vibration frequency is close to the characteristic frequency of rigid airfoil. Evolution and shedding of vortices corresponding to the deformation of flexible structure depends on the Reynolds number. In the case of Re≤1000, the deformation of flexible structure is considered in-phase with the vortex shedding i.e., increasing maximum lift is linked with the positive deformation of flexible structure. At Re=1500 a phase shift of about 1/π exists while they are out-of-phase at Re>1500. Moreover, the oscillation amplitude of lift coefficient increases with increasing vibration amplitude for Re≤1500 while it decreases with increasing vibration amplitude for Re>1500. As a result of frequency lock-in, the average lift coefficient is increased with increasing vibration amplitude for all investigated Reynolds numbers (Re. The maximum increase in the average lift coefficient is 19.72% within the range of investigated parameters.

  16. Flow past two tandem square cylinders vibrating transversely in phase

    International Nuclear Information System (INIS)

    Mithun, M G; Tiwari, Shaligram

    2014-01-01

    Numerical investigations have been carried out to study the wake characteristics of flow past two tandem square cylinders vibrating in phase. Both the cylinders vibrate in a transverse direction, i.e., perpendicular to the incoming flow with the same frequency and amplitude. The frequency of vibration of the cylinders and the inter-cylinder spacing are varied for fixed values of the Reynolds number (Re = 100) and the amplitude ratio (A/D = 0.4). The synchronous or lock-in regime for the oscillatory wake of the vibrating cylinders has been identified by varying the frequency of the vibration from f e  = 0.4 f 0 to 1.6 f 0 (f 0 being the frequency of vortex shedding behind a stationary square cylinder). The characteristics of lift and drag and the mechanism of vortex shedding are studied by varying the excitation frequency within the lock-in range for each value of inter-cylinder spacing. The complex interaction of flow between the cylinders gives rise to a variety of characteristically different shedding patterns in their wake. For values of inter-cylinder spacing equal to 2D and 3D, periodic, as well as quasi-periodic, lock-in behaviors are observed in the synchronous range. (paper)

  17. Multi-Exciter Vibroacoustic Simulation of Hypersonic Flight Vibration

    International Nuclear Information System (INIS)

    GREGORY, DANNY LYNN; CAP, JEROME S.; TOGAMI, THOMAS C.; NUSSER, MICHAEL A.; HOLLINGSHEAD, JAMES RONALD

    1999-01-01

    Many aerospace structures must survive severe high frequency, hypersonic, random vibration during their flights. The random vibrations are generated by the turbulent boundary layer developed along the exterior of the structures during flight. These environments have not been simulated very well in the past using a fixed-based, single exciter input with an upper frequency range of 2 kHz. This study investigates the possibility of using acoustic ardor independently controlled multiple exciters to more accurately simulate hypersonic flight vibration. The test configuration, equipment, and methodology are described. Comparisons with actual flight measurements and previous single exciter simulations are also presented

  18. A wireless vibrating wire sensor node for continuous structural health monitoring

    International Nuclear Information System (INIS)

    Lee, H M; Park, H S; Kim, J M; Sho, K

    2010-01-01

    Vibrating wire sensors (VWS) are generally used for strain measurements of structures in buildings and civil infrastructures. In this paper, a wireless vibrating wire sensor node is developed which can measure resonance frequencies from vibrating wire sensors and can remotely communicate the frequencies by wireless. The wireless sensor node consists of a sensor module, which excites the vibrating wire and reads the resonance frequencies, a wireless communication module, which transmits the wire's resonance frequencies to the user or administrator, and a processor that controls the two modules. The wireless sensor node has the following characteristics: it has multiple channels to enable measurement of multiple vibrating wire sensors (up to four) using a single sensor node; it has a power-saving feature that enables operation for up to one year; and lastly, the wireless unit uses the 424 MHz UHF (ultra-high frequency) band with good diffraction that has an effect on minimizing the influence of impediments such as structural or nonstructural elements. The wireless sensor node is tested in terms of its measurement precision and its wireless communication performance. As a result, it is confirmed that the node enables the long-term structural health monitoring of buildings and infrastructures

  19. Research on the design of fixture for motor vibration test

    Science.gov (United States)

    Shen, W. X.; Ma, W. S.; Zhang, L. W.

    2018-03-01

    The vibration reliability of the new energy automobile motor plays a very important role in driving safety, so it is very important to test the vibration durability of the motor. In the vibration test process, the fixture is very important, simulated road spectrum signal vibration can be transmitted without distortion to the motor through the fixture, fixture design directly affect the result of vibration endurance test. On the basis of new energy electric vehicle motor concrete structure, Two fixture design and fixture installation schemes for lateral cantilever type and base bearing type are put forward in this article, the selection of material, weighting process, middle alignment process and manufacturing process are summarized.The modal analysis and frequency response calculation of the fixture are carried out in this design, combine with influence caused by fixture height and structure profile on response frequency, the response frequency of each order of the fixture is calculated, then ultimately achieve the purpose of guiding the design.

  20. Complete flexural vibration band gaps in membrane-like lattice structures

    International Nuclear Information System (INIS)

    Yu Dianlong; Liu Yaozong; Qiu Jing; Wang Gang; Zhao Honggang

    2006-01-01

    The propagation of flexural vibration in the periodical membrane-like lattice structure is studied. The band structure calculated with the plane wave expansion method indicates the existence of complete gaps. The frequency response function of a finite periodic structure is simulated with finite element method. Frequency ranges with vibration attenuation are in good agreement with the gaps found in the band structure. Much larger attenuations are found in the complete gaps comparing to those directional ones. The existence of complete flexural vibration gaps in such a lattice structure provides a new idea for vibration control of thin plates

  1. Vibrational Spectroscopic Studies of Tenofovir Using Density Functional Theory Method

    Directory of Open Access Journals (Sweden)

    G. R. Ramkumaar

    2013-01-01

    Full Text Available A systematic vibrational spectroscopic assignment and analysis of tenofovir has been carried out by using FTIR and FT-Raman spectral data. The vibrational analysis was aided by electronic structure calculations—hybrid density functional methods (B3LYP/6-311++G(d,p, B3LYP/6-31G(d,p, and B3PW91/6-31G(d,p. Molecular equilibrium geometries, electronic energies, IR intensities, and harmonic vibrational frequencies have been computed. The assignments proposed based on the experimental IR and Raman spectra have been reviewed and complete assignment of the observed spectra have been proposed. UV-visible spectrum of the compound was also recorded and the electronic properties such as HOMO and LUMO energies and were determined by time-dependent DFT (TD-DFT method. The geometrical, thermodynamical parameters, and absorption wavelengths were compared with the experimental data. The B3LYP/6-311++G(d,p-, B3LYP/6-31G(d,p-, and B3PW91/6-31G(d,p-based NMR calculation procedure was also done. It was used to assign the 13C and 1H NMR chemical shift of tenofovir.

  2. Vibrations as a contributor to the cracking of PGV-1000 steam generator cold collector

    International Nuclear Information System (INIS)

    Verezemskij, V.G.

    1997-01-01

    The results of multiple investigations of cold collector ruptures at NPPs with WWER-1000 reactor as a complex and multi-parameter process are generalized. It is shown that the temperature of cold collector operation (280-290 deg C) at which environment corrosion effects are maximum has an important role for revealing the factors causing the damage. When the reactor plant operates under stationary and transient conditions the primary coolant circuit equipment, main circulation pipelines and main steam lines become involved into vibrations with different intensities as a result of pressure pulsations at reverse and multiple frequencies of the main circulation pumps connected with formation of standing pressure waves in the primary circuit and steam lines. The analysis made gives an opportunity to conclude that dynamic loads (vibrations) play the leading part in reaching the limits of cold collector metal cyclic strength and its cracking. It means that the measures for cold collector service life increasing should be directed on vibration amplitude lowering and cyclic stress decreasing

  3. Mitigating ground vibration by periodic inclusions and surface structures

    DEFF Research Database (Denmark)

    Andersen, Lars Vabbersgaard; Bucinskas, Paulius; Persson, Peter

    2016-01-01

    Ground vibration from traffic is a source of nuisance in urbanized areas. Trenches and wave barriers can provide mitigation of vibrations, but single barriers need to have a large depth to be effective-especially in the low-frequency range relevant to traffic-induced vibration. Alternatively...

  4. Vibration stress relief treatment in welded samples of ST-3 steel

    International Nuclear Information System (INIS)

    Suarez, J.C.; Fernandez, L.M.; Echevarria, J.F.; Estevez, A.; Perez, A.; Aragon, B.

    1996-01-01

    The presented work is aimed to find the optimal vibration frequency and treatment duration for ST-3 steel welded test pieces. In the experiment transversal stresses were not virtually relieved by the application of vibrations at the three natural frecuencies. With regard to the optimal frequency for our system, the firths natural frequency appears to be most effective one, wherewith a maximum 35-70 % longitudinal stress relief was obtained. The influence of the propagation direction (transversal or longitudinal) of vibrations on stress relief in a welded joint was confirmed

  5. Performance studies of the vibration wire monitor on the test stand with low energy electron beam

    International Nuclear Information System (INIS)

    Okabe, Kota; Yoshimoto, Masahiro; Kinsho, Michikazu

    2015-01-01

    In the high intensity proton accelerator as the Japan Proton Accelerator Research Complex (J-PARC) accelerators, serious radiation and residual dose is induced by a small beam loss such a beam halo. Therefore, diagnostics of the beam halo formation is one of the most important issues to control the beam loss. For the beam halo monitor, the vibration wire monitor (VWM) has a potential for investigating the beam halo and weak beam scanning. The VWM has a wide dynamic range, high resolution and the VWM is not susceptible to secondary electrons and electric noises. We have studied the VWM features as a new beam-halo monitor on the test stand with low energy electron gun. The frequency shift of the irradiated vibration wire was confirmed about wire material and the electron beam profile measured by using the VWM was consistent with the results of the Faraday cup measurement. Also we calculated a temperature distribution on the vibration wire which is irradiated by the electron beam with the numerical simulation. The simulations have been fairly successful in reproducing the transient of the irradiated vibration wire frequency measured by test stand experiments. In this paper, we will report a result of performance evaluation for the VWM on the test stands and discuss the VWM for beam halo diagnostic. (author)

  6. Hybrid nanogenerators for low frequency vibration energy harvesting and self-powered wireless locating

    Science.gov (United States)

    Yuan, Ying; Zhang, Hulin; Wang, Jie; Xie, Yuhang; Khan, Saeed Ahmed; Jin, Long; Yan, Zhuocheng; Huang, Long; Pan, Taisong; Yang, Weiqing; Lin, Yuan

    2018-01-01

    Hybrid energy harvesters based on different physical effects is fascinating, but a rational design for multiple energy harvesting is challenging. In this work, a spring-magnet oscillator-based triboelectric-electromagnetic generator (EMG) with a solar cell cap is proposed. A power was produced by a triboelectric nanogenerator (TENG) and an EMG independently or simultaneously by using a shared spring-magnet oscillator. The oscillator configuration enables versatile energy harvesting with the excellent size scalability and self-packaged structure which can perform well at low frequency ranging from 3.5 to 5 Hz. The solar cell cap mounted above the oscillator can harvest solar energy. Under vibrations at the frequency of 4 Hz, the TENG and the EMG produced maximum output power of 5.46 nW cm-3 and 378.79 μW cm-3, respectively. The generated electricity by the hybrid nanogenerator can be stored in a capacitor or Li-ion battery, which is capable of powering a wireless locator for real-time locating data reporting to a personal cell phone. The light-weight and handy hybrid nanogenerator can directly light a caution light or play as a portable flashlight by shaking hands at night.

  7. Development of an innovative device for ultrasonic elliptical vibration cutting.

    Science.gov (United States)

    Zhou, Ming; Hu, Linhua

    2015-07-01

    An innovative ultrasonic elliptical vibration cutting (UEVC) device with 1st resonant mode of longitudinal vibration and 3rd resonant mode of bending vibration was proposed in this paper, which can deliver higher output power compared to previous UEVC devices. Using finite element method (FEM), resonance frequencies of the longitudinal and bending vibrations were tuned to be as close as possible in order to excite these two vibrations using two-phase driving voltages at a single frequency, while wave nodes of the longitudinal and bending vibrations were also adjusted to be as coincident as possible for mounting the device at a single fixed point. Based on the simulation analysis results a prototype device was fabricated, then its vibration characteristics were evaluated by an impedance analyzer and a laser displacement sensor. With two-phase sinusoidal driving voltages both of 480 V(p-p) at an ultrasonic frequency of 20.1 kHz, the developed prototype device achieved an elliptical vibration with a longitudinal amplitude of 8.9 μm and a bending amplitude of 11.3 μm. The performance of the developed UEVC device is assessed by the cutting tests of hardened steel using single crystal diamond tools. Experimental results indicate that compared to ordinary cutting process, the tool wear is reduced significantly by using the proposed device. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Narrow bandwidth detection of vibration signature using fiber lasers

    Science.gov (United States)

    Moore, Sean; Soh, Daniel B.S.

    2018-05-08

    The various technologies presented herein relate to extracting a portion of each pulse in a series of pulses reflected from a target to facilitate determination of a Doppler-shifted frequency for each pulse and, subsequently, a vibration frequency for the series of pulses. Each pulse can have a square-wave configuration, whereby each pulse can be time-gated to facilitate discarding the leading edge and the trailing edge (and associated non-linear effects) of each pulse and accordingly, capture of the central portion of the pulse from which the Doppler-shifted frequency, and ultimately, the vibration frequency of the target can be determined. Determination of the vibration velocity facilitates identification of the target being in a state of motion. The plurality of pulses can be formed from a laser beam (e.g., a continuous wave), the laser beam having a narrow bandwidth.

  9. Frequency and determinants of drug administration errors in the intensive care unit

    NARCIS (Netherlands)

    van den Bemt, PMLA; Fijn, R; van der Voort, PHJ; Gossen, AA; Egberts, TCG; Brouwers, JRBJ

    Objective., The study aimed to identify both the frequency and the determinants of drug administration errors in the intensive care unit. Design: Administration errors were detected by using the disguised-observation technique (observation of medication administrations by nurses, without revealing

  10. The vibration measurements at the photon factory storage ring building

    International Nuclear Information System (INIS)

    Haga, K.; Nakayama, M.; Masuda, K.; Ishizaki, H.; Kura, M.; Meng, L.; Oku, Y.

    1999-01-01

    The Photon Factory is a 2.5 GeV electron storage ring and has been operating since 1982 as a dedicated SR source. At the Photon Factory, we have been pursuing the various sources of the beam instabilities which deteriorated the SR beam quality in the wide frequency range. Some of the sources were the vibrations of magnets and floor of the ring tunnel, temperature change of the cooling water and the elongation of the storage ring building roof due to sunshine that induced the diurnal motion of the SR beam axis. This article presents the results of the vibration measurements that have been performed at the Photon Factory storage ring building. (1) The vibrations of the ring tunnel floor and the experimental hall floor, comparing with the vibration of the ground surrounding the storage ring building, are same order in the 1 ∼ 5 Hz range, and 1/3 ∼ 1/5 in the 5 ∼ 100 Hz range, in the vertical and the horizontal direction. (2) The effects of the vibration arising from the operating eight air-conditioners can be seen in the Fourier spectrum of the vibration of the ring tunnel floor, experimental floor, Q-magnets and BPM vacuum duct. (3) The vibrations of the Q-magnet and girder at frequencies near their fundamental resonant frequencies have been amplified 100 limes in the lateral direction comparing to the floor vibration. (4) Correlation between the vibration of the BPM vacuum duct and the vibration of the electron beam motion is unknown for the lack of the precise data. (authors)

  11. Resonant vibrations of self-interstitials in fcc metals with application to specific heat and neutron scattering

    International Nuclear Information System (INIS)

    Ram, P.N.; Dederichs, P.H.

    1981-07-01

    Some aspects of resonant vibrations of self-interstitials in the 100-dumbbell configuration in fcc-metals are discussed by extending previous calculations of Zeller et al. and Schober et al. Employing a simple defect model with nearest-neighbour interaction the local frequency spectrum of the defect is calculated showing several localized modes and low-frequency resonant modes. The change in the total density of states due to the defects is expressed as the derivative of a generalized phase shift which is used to calculate the change in the lattic specific heat due to single interstitials. Inelastic neutron scattering away from the one-phonon lines is proposed as a method to observe the resonant modes induced by self-interstitials. The model calculation in Cu shows that the well defined resonant modes due to dumbbell vibrations have appreciable intensity and could presumably be detected in neutron scattering measurements. The effect of di-interstitials on the phonon dispersion in Al is also discussed. (orig./GSCH)

  12. Vibrational Characteristics of ring-type ultrasonic motor stator using ESPI

    International Nuclear Information System (INIS)

    Jung, Hyun Kyu; Paik, Sung Hoon; Kim, Seung Ho; Park, Ki Jun; Wang, Young Sung

    2001-01-01

    A stator of ring-type ultrasonic motor composed of the piezoelectric ceramic and the elastic metal was made to generate the travelling wave. Vibrational behavior of the stator was simulated by a finite element analysis using ATILA program and was measured by the electronic speckle pattern interferometry (ESPI) method. The resonance frequencies and vibration modes were analysed depending upon the comparison between the finite element analysis and ESPI measurement. The optimal vibration mode and frequency was estimated to be 7th resonant mode which was corresponded to the measured frequency of 39 KHz. It could be concluded that this fabricated stator can be applied for ring-type ultrasonic motor.

  13. Quantifying Changes in Future Intensity-Duration-Frequency Curves Using Multimodel Ensemble Simulations

    Science.gov (United States)

    Ragno, Elisa; AghaKouchak, Amir; Love, Charlotte A.; Cheng, Linyin; Vahedifard, Farshid; Lima, Carlos H. R.

    2018-03-01

    During the last century, we have observed a warming climate with more intense precipitation extremes in some regions, likely due to increases in the atmosphere's water holding capacity. Traditionally, infrastructure design and rainfall-triggered landslide models rely on the notion of stationarity, which assumes that the statistics of extremes do not change significantly over time. However, in a warming climate, infrastructures and natural slopes will likely face more severe climatic conditions, with potential human and socioeconomical consequences. Here we outline a framework for quantifying climate change impacts based on the magnitude and frequency of extreme rainfall events using bias corrected historical and multimodel projected precipitation extremes. The approach evaluates changes in rainfall Intensity-Duration-Frequency (IDF) curves and their uncertainty bounds using a nonstationary model based on Bayesian inference. We show that highly populated areas across the United States may experience extreme precipitation events up to 20% more intense and twice as frequent, relative to historical records, despite the expectation of unchanged annual mean precipitation. Since IDF curves are widely used for infrastructure design and risk assessment, the proposed framework offers an avenue for assessing resilience of infrastructure and landslide hazard in a warming climate.

  14. The potential benefits and inherent risks of vibration as a non-drug therapy for the prevention and treatment of osteoporosis.

    Science.gov (United States)

    Chan, M Ete; Uzer, Gunes; Rubin, Clinton T

    2013-03-01

    The delivery of mechanical signals to the skeleton using vibration is being considered as a non-drug treatment of osteoporosis. Delivered over a range of magnitudes and frequencies, vibration has been shown to be both anabolic and anti-catabolic to the musculoskeletal tissues, yet caution must be emphasized as these mechanical signals, particularly chronic exposure to higher intensities, is a known pathogen to many physiological systems. In contrast, accumulating preclinical and clinical evidence indicates that low intensity vibration (LIV) improves bone quality through regulating the activity of cells responsible for bone remodeling, as well as biasing the differentiation fate of their mesenchymal and hematopoietic stem cell progenitors. In vitro studies provide insights into the biologic mechanisms of LIV, and indicate that cells respond to these low magnitude signals through a distinct mechanism driven not by matrix strain but acceleration. These cell, animal, and human studies may represent the foundation of a safe, non-drug means to protect and improve the musculoskeletal system of the elderly, injured, and infirmed.

  15. Controlling coupled bending-twisting vibrations of anisotropic composite wing

    Science.gov (United States)

    Ryabov, Victor; Yartsev, Boris

    2018-05-01

    The paper discusses the possibility to control coupled bending-twisting vibrations of anisotropic composite wing by means of the monoclinic structures in the reinforcement of the plating. Decomposing the potential straining energy and kinetic energy of natural vibration modes into interacting and non-interacting parts, it became possible to introduce the two coefficients that integrally consider the effect of geometry and reinforcement structure upon the dynamic response parameters of the wing. The first of these coefficients describes the elastic coupling of the natural vibration modes, the second coefficient describes the inertial one. The paper describes the numerical studies showing how the orientation of considerably anisotropic CRP layers in the plating affects natural frequencies, loss factors, coefficients of elastic and inertial coupling for several lower tones of natural bending-twisting vibrations of the wing. Besides, for each vibration mode, partial values of the above mentioned dynamic response parameters were determined by means of the relationships for orthotropic structures where instead of "free" shearing modulus in the reinforcement plant, "pure" shearing modulus is used. Joint analysis of the obtained results has shown that each pair of bending-twisting vibration modes has its orientation angle ranges of the reinforcing layers where the inertial coupling caused by asymmetry of the cross-section profile with respect to the main axes of inertia decreases, down to the complete extinction, due to the generation of the elastic coupling in the plating material. These ranges are characterized by the two main features: 1) the difference in the natural frequencies of the investigated pair of bending-twisting vibration modes is the minimum and 2) natural frequencies of bending-twisting vibrations belong to a stretch restricted by corresponding partial natural frequencies of the investigated pair of vibration modes. This result is of practical importance

  16. Mapping of lichen frequencies as a tool in evaluating intensity of pollution

    Energy Technology Data Exchange (ETDEWEB)

    Kunze, M

    1972-01-01

    A method is presented for determining the intensity of air pollution by evaluating the frequency of lichen species growing on the trunks of trees. The lichens growing on the trunks of isolated trees in the surroundings of factories or other pollutants have been investigated. A ladder enclosing the panels is used to determine the frequency: the calculation is made electronically and permits statistical statements about the quantity of the lichens to be made. The numerical material evaluated consists of reproduceable data obtained by a standardized method that appears to be suitable for routine use. Pollution zones can be recognized by changes in frequency of the various sensitive species.

  17. Ring-like size segregation in vibrated cylinder with a bottleneck

    International Nuclear Information System (INIS)

    Kong Xiangzhao; Hu Maobin; Wu Qingsong; Wu Yonghong

    2005-01-01

    In this Letter, a ring-like segregation pattern of bi-dispersed granular material in a vibrated bottleneck-cylinder is presented. The driving frequency can greatly affect the strength and structure of the convection roll and segregation pattern. The position and height of the ring (cluster of big beads) can be adjusted by altering the vibration frequency. And a heuristic theory is developed to interpret the ring's position dependence on driving frequency

  18. Vibration Analysis of a Residential Building

    Directory of Open Access Journals (Sweden)

    Sampaio Regina Augusta

    2015-01-01

    Full Text Available The aim of this paper is to present the results of a study regarding vibration problems in a 17 storey residential building during pile driving in its vicinity. The structural design of the building was checked according to the Brazilian standards NBR6118 and NBR6123, and using commercial finite element software. An experimental analysis was also carried out using low frequency piezo-accelerometers attached to the building structure. Structure vibrations were recorded under ambient conditions. Four monitoring tests were performed on different days. The objective of the first monitoring test was an experimental modal analysis. To obtain de modal parameters, data was processed in the commercial software ARTEMIS employing two methods: the Stochastic Subspace Identification and the Frequency Domain Decomposition. Human comfort was investigated considering the International Standard ISO 2631. The Portuguese standard, NP2074, was also used as a reference, since it aims to limit the adverse effects of vibrations in structures caused by pile driving in the vicinity of the structure. The carried out experimental tests have shown that, according to ISO2301, the measure vibration levels are above the acceptance limits. However, velocity peaks are below the limits established by NP2074. It was concluded that, although the structure has adequate capacity to resist internal forces according to normative criteria, it has low horizontal stiffness, which could be verified by observing the vibration frequencies and mode shapes obtained with the finite element models, and its similarity with the experimental results. Thus, the analyses indicate the occurrence of discomfort by the residents.

  19. Effects of cations and cholesterol with sphingomyelin membranes investigated by high-resolution broadband sum frequency vibrational spectroscopy

    Science.gov (United States)

    Zhang, Zhen; Feng, Rong-juan; Li, Yi-yi; Liu, Ming-hua; Guo, Yuan

    2017-08-01

    Sphingomyelin(SM) is specifically enriched in the plasma membrane of mammalian cells. Its molecular structure is compose by N-acyl-Derythro-sphingosylphosphorylcholine. The function of the SM related to membrane signaling and protein trafficking are relied on the interactions of the SM, cations, cholesterol and proteins. In this report, the interaction of three different nature SMs, cations and cholesterol at air/aqueous interfaces studied by high-resolution broadband sum frequency vibrational spectroscopy, respectively. Our results shed lights on understanding the relationship between SMs monolayer, cholesterol and Cations.

  20. Experimental Study of Annulus Flow for Can Combustor with Vibration Influence

    Directory of Open Access Journals (Sweden)

    Rami. Y. Dahham

    2018-01-01

    Full Text Available This paper concentrate on studying the behavior of velocity profile under the influence of different frequency (34, 48, 65 and 80 Hz in each of the upper and lower annulus of Can Combustor.An experimental rig was designed to simulate the annulus flow inside a Can Combustor.The Can Combustor tested in this study is real part collected from Al-Khairat/Iraq gas turbine power station.The velocity profiles are investigated at three positions in the annular for upper and lower region.The axial velocity and turbulence intensity are calculating with different frequency for upper and lower annulus.The results were shown that the increase of frequency lead to increase the velocity profile and large recirculation zone will build in some points.Reynolds number increasing with raise of axial velocity. Also the increasing in vibration level cause non-uniform velocity profile which affect on distribution of cooling effectiveness.

  1. Sound and vibration sensitivity of VIIIth nerve fibers in the grassfrog, Rana temporaria

    DEFF Research Database (Denmark)

    Christensen-Dalsgaard, J; Jørgensen, M B

    1996-01-01

    thresholds from 0.02 cm/s2. The sound and vibration sensitivity was compared for each fiber using the offset between the rate-level curves for sound and vibration stimulation as a measure of relative vibration sensitivity. When measured in this way relative vibration sensitivity decreases with frequency from......We have studied the sound and vibration sensitivity of 164 amphibian papilla fibers in the VIIIth nerve of the grassfrog, Rana temporaria. The VIIIth nerve was exposed using a dorsal approach. The frogs were placed in a natural sitting posture and stimulated by free-field sound. Furthermore......, the animals were stimulated with dorso-ventral vibrations, and the sound-induced vertical vibrations in the setup could be canceled by emitting vibrations in antiphase from the vibration exciter. All low-frequency fibers responded to both sound and vibration with sound thresholds from 23 dB SPL and vibration...

  2. Analysis of musle fatigue induced by isometric vibration exercise at varying frequencies

    NARCIS (Netherlands)

    Mischi, M.; Rabotti, C.; Cardinale, M. (Marco)

    2012-01-01

    An increase in neuromuscular activity, measured by electromyography (EMG), is usually observed during vibration exercise. The underlying mechanisms are however unclear, limiting the possibilities to introduce and exploit vibration training in rehabilitation programs. In this study, a new training

  3. Efficient forced vibration reanalysis method for rotating electric machines

    Science.gov (United States)

    Saito, Akira; Suzuki, Hiromitsu; Kuroishi, Masakatsu; Nakai, Hideo

    2015-01-01

    Rotating electric machines are subject to forced vibration by magnetic force excitation with wide-band frequency spectrum that are dependent on the operating conditions. Therefore, when designing the electric machines, it is inevitable to compute the vibration response of the machines at various operating conditions efficiently and accurately. This paper presents an efficient frequency-domain vibration analysis method for the electric machines. The method enables the efficient re-analysis of the vibration response of electric machines at various operating conditions without the necessity to re-compute the harmonic response by finite element analyses. Theoretical background of the proposed method is provided, which is based on the modal reduction of the magnetic force excitation by a set of amplitude-modulated standing-waves. The method is applied to the forced response vibration of the interior permanent magnet motor at a fixed operating condition. The results computed by the proposed method agree very well with those computed by the conventional harmonic response analysis by the FEA. The proposed method is then applied to the spin-up test condition to demonstrate its applicability to various operating conditions. It is observed that the proposed method can successfully be applied to the spin-up test conditions, and the measured dominant frequency peaks in the frequency response can be well captured by the proposed approach.

  4. Vibration analysis of the piping system using the modal analysis method, 1

    International Nuclear Information System (INIS)

    Fujikawa, Takeshi; Kurohashi, Michiya; Inoue, Yoshio

    1975-01-01

    Modal analysis method was developed for the vibration analysis of piping system in nuclear or chemical plants, with finite element theory, and verified by sinusoidal vibration method. The natural vibration equation for pipings was derived with stiffness, attenuation and mass matrices, and eigenvalues are obtained with usual method, then the forced vibration equation for pipings was derived with the same manner, and the special solutions are given by modal method from the eigenvalues of the natural vibration equation. Three simple piping models (one, two and three dimensional) were made, and the natural vibration frequency was measured with forced input from an electrical dynamic shaker and a sound speaker. The experimental values of natural vibration frequency showed good agreement with the results by the analytical method. Therefore the theoretical approach for piping system vibration was proved to be valid. (Iwase, T.)

  5. Vibration test report for in-chimney bracket and instrumented fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jeong Soo; Yoon, D. B.; Cho, Y. G.; Ahn, G. H.; Lee, J. H.; Park, J.H

    2000-10-01

    The vibration levels of in-chimney bracket structure which is installed in reactor chimney and instrumented fuel assembly(Type-B Bundle) are investigated under the steady state normal operating condition of the reactor. For this purpose, 4 acceleration data on the guide tube of the instrumented fuel assembly and in-chimney bracket structures subjected to fluid induced vibration are measured. For the analysis of the vibration data, vibration analysis program which can perform basic time and frequency domain analysis, is prepared, and its reliability is verified by comparing the analysis results with those of commercial analysis program(I-DEAS). In time domain analysis, maximum amplitudes, and RMS values of accelerations and displacements from the measured vibration signal, are obtained. The frequency components of the vibration data are analyzed by using the frequency domain analysis. These analysis results show that the levels of the measured vibrations are within the allowable level, and the low frequency component near 10 Hz is dominant in the vibration signal. For the evaluation of the structural integrity on the in-chimney bracket and related structures including the instrumented fuel assembly, the static analysis for ANSYS finite element model is carried out. These analysis results show that the maximum stresses are within the allowable stresses of the ASME code, and the maximum displacement of the top of the flow tube is within the displacement limit. Therefore any damage on the structural integrity is not expected when the irradiation test is performed using the in-chimney bracket.

  6. Vibration test report for in-chimney bracket and instrumented fuel assembly

    International Nuclear Information System (INIS)

    Ryu, Jeong Soo; Yoon, D. B.; Cho, Y. G.; Ahn, G. H.; Lee, J. H.; Park, J.H.

    2000-10-01

    The vibration levels of in-chimney bracket structure which is installed in reactor chimney and instrumented fuel assembly(Type-B Bundle) are investigated under the steady state normal operating condition of the reactor. For this purpose, 4 acceleration data on the guide tube of the instrumented fuel assembly and in-chimney bracket structures subjected to fluid induced vibration are measured. For the analysis of the vibration data, vibration analysis program which can perform basic time and frequency domain analysis, is prepared, and its reliability is verified by comparing the analysis results with those of commercial analysis program(I-DEAS). In time domain analysis, maximum amplitudes, and RMS values of accelerations and displacements from the measured vibration signal, are obtained. The frequency components of the vibration data are analyzed by using the frequency domain analysis. These analysis results show that the levels of the measured vibrations are within the allowable level, and the low frequency component near 10 Hz is dominant in the vibration signal. For the evaluation of the structural integrity on the in-chimney bracket and related structures including the instrumented fuel assembly, the static analysis for ANSYS finite element model is carried out. These analysis results show that the maximum stresses are within the allowable stresses of the ASME code, and the maximum displacement of the top of the flow tube is within the displacement limit. Therefore any damage on the structural integrity is not expected when the irradiation test is performed using the in-chimney bracket

  7. Vibronic Rabi resonances in harmonic and hard-wall ion traps for arbitrary laser intensity and detuning

    International Nuclear Information System (INIS)

    Lizuain, I.; Muga, J. G.

    2007-01-01

    We investigate laser-driven vibronic transitions of a single two-level atomic ion in harmonic and hard-wall traps. In the Lamb-Dicke regime, for tuned or detuned lasers with respect to the internal frequency of the ion, and weak or strong laser intensities, the vibronic transitions occur at well-isolated Rabi resonances, where the detuning-adapted Rabi frequency coincides with the transition frequency between vibrational modes. These vibronic resonances are characterized as avoided crossings of the dressed levels (eigenvalues of the full Hamiltonian). Their peculiarities due to symmetry constraints and trapping potential are also examined

  8. Study on the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration

    International Nuclear Information System (INIS)

    Lin Shuyu; Tian Hua

    2008-01-01

    A sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is studied. The transducer consists of front and back metal masses, and coaxially segmented, thickness polarized piezoelectric ceramic thin rings. For this kind of sandwich piezoelectric transducers in thickness vibration, it is required that the lateral dimension of the transducer is sufficiently large compared with its longitudinal dimension so that no lateral displacements in the transducer can occur (laterally clamped). In this paper, the thickness vibration of the piezoelectric ceramic stack consisting of a number of identical piezoelectric ceramic thin rings is analysed and its electro-mechanical equivalent circuit is obtained. The resonance frequency equation for the sandwich piezoelectric ceramic ultrasonic transducer in thickness vibration is derived. Based on the frequency equation, two sandwich piezoelectric ceramic ultrasonic transducers are designed and manufactured, and their resonance frequencies are measured. It is shown that the measured resonance frequencies are in good agreement with the theoretical results. This kind of sandwich piezoelectric ultrasonic transducer is expected to be used in megasonic ultrasonic cleaning and sonochemistry where high power and high frequency ultrasound is needed

  9. Strouhal number effect on synchronized vibration range of a circular cylinder in cross flow

    International Nuclear Information System (INIS)

    Kawamura, T.; Nakao, T.; Hayashi, M.; Murayama, K.

    2001-01-01

    Synchronized vibrations were measured for a circular cylinder subjected to a water cross flow in the subcritical Reynolds numbers in order to compare the synchronized vibration range between the subcritical and supercritical regions and clarify the effect of the Strouhal number on it. A small peak vibration in the lift direction was found when the Karman vortex shedding frequency was about 1/5 of the cylinder natural frequency in only the subcritical region. The ratio of the Karman vortex frequency to the natural frequency where the self-excited vibration in the drag direction by the symmetrical vortices began was about 1/4 in the subcritical region, and increased to 0,32 at the Strouhal number of 0,29 in the supercritical region. The frequency ratio at the beginning of the lock-in vibration in the drag direction by the Karman vortex was about 1/2, and that in the lift direction decreased from 1 to about 0,8 with decreasing Strouhal number. (author)

  10. Anomalous vibrational properties in the continuum limit of glasses

    Science.gov (United States)

    Shimada, Masanari; Mizuno, Hideyuki; Ikeda, Atsushi

    2018-02-01

    The low-temperature thermal properties of glasses are anomalous with respect to those of crystals. These thermal anomalies indicate that the low-frequency vibrational properties of glasses differ from those of crystals. Recent studies revealed that, in the simplest model of glasses, i.e., the harmonic potential system, phonon modes coexist with soft localized modes in the low-frequency (continuum) limit. However, the nature of low-frequency vibrational modes of more realistic models is still controversial. In the present work, we study the Lennard-Jones (LJ) system using large-scale molecular-dynamics (MD) simulation and establish that the vibrational property of the LJ glass converges to coexistence of the phonon modes and the soft localized modes in the continuum limit as in the case of the harmonic potential system. Importantly, we find that the low-frequency vibrations are rather sensitive to the numerical scheme of potential truncation, which is usually implemented in the MD simulation, and this is the reason why contradictory arguments have been reported by previous works. We also discuss the physical origin of this sensitiveness by means of a linear stability analysis.

  11. Analysis on Coupled Vibration of a Radially Polarized Piezoelectric Cylindrical Transducer

    Directory of Open Access Journals (Sweden)

    Jie Xu

    2017-12-01

    Full Text Available Coupled vibration of a radially polarized piezoelectric cylindrical transducer is analyzed with the mechanical coupling coefficient method. The method has been utilized to analyze the metal cylindrical transducer and the axially polarized piezoelectric cylindrical transducer. In this method, the mechanical coupling coefficient is introduced and defined as the stress ratio in different directions. Coupled vibration of the cylindrical transducer is regarded as the interaction of the plane radial vibration of a ring and the longitudinal vibration of a tube. For the radially polarized piezoelectric cylindrical transducer, the radial and longitudinal electric admittances as functions of mechanical coupling coefficients and angular frequencies are derived, respectively. The resonance frequency equations are obtained. The dependence of resonance frequency and mechanical coupling coefficient on aspect ratio is studied. Vibrational distributions on the surfaces of the cylindrical transducer are presented with experimental measurement. On the support of experiments, this work is verified and provides a theoretical foundation for the analysis and design of the radially polarized piezoelectric cylindrical transducer.

  12. Experimental Study on Piezoelectric Energy Harvesting from Vortex-Induced Vibrations and Wake-Induced Vibrations

    Directory of Open Access Journals (Sweden)

    Min Zhang

    2016-01-01

    Full Text Available A rigid circular cylinder with two piezoelectric beams attached on has been tested through vortex-induced vibrations (VIV and wake-induced vibrations (WIV by installing a big cylinder fixed upstream, in order to study the influence of the different flow-induced vibrations (FIV types. The VIV test shows that the output voltage increases with the increases of load resistance; an optimal load resistance exists for the maximum output power. The WIV test shows that the vibration of the small cylinder is controlled by the vortex frequency of the large one. There is an optimal gap of the cylinders that can obtain the maximum output voltage and power. For a same energy harvesting device, WIV has higher power generation capacity; then the piezoelectric output characteristics can be effectively improved.

  13. Vibrational analysis of single-layered graphene sheets

    Energy Technology Data Exchange (ETDEWEB)

    Sakhaee-Pour, A; Ahmadian, M T [Center of Excellence in Design, Robotics and Automation (CEDRA), Department of Mechanical Engineering, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Naghdabadi, R [Department of Mechanical Engineering and Institute for Nano Science and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: sakhaee@alum.sharif.edu, E-mail: naghdabd@sharif.edu

    2008-02-27

    A molecular structural mechanics method has been implemented to investigate the vibrational behavior of single-layered graphene sheets. By adopting this approach, mode shapes and natural frequencies are obtained. Vibrational analysis is performed with different chirality and boundary conditions. Numerical results from the atomistic modeling are employed to develop predictive equations via a statistical nonlinear regression model. With the proposed equations, fundamental frequencies of single-layered graphene sheets with considered boundary conditions can be predicted within 3% difference with respect to the atomistic simulation.

  14. Vibrational analysis of 4-chloro-3-nitrobenzonitrile by quantum chemical calculations

    Science.gov (United States)

    Sert, Yusuf; Çırak, Çağrı; Ucun, Fatih

    2013-04-01

    In the present study, the experimental and theoretical harmonic and anharmonic vibrational frequencies of 4-chloro-3-nitrobenzonitrile were investigated. The experimental FT-IR (400-4000 cm-1) and μ-Raman spectra (100-4000 cm-1) of the molecule in the solid phase were recorded. Theoretical vibrational frequencies and geometric parameters (bond lengths and bond angles) were calculated using ab initio Hartree Fock (HF), density functional B3LYP and M06-2X methods with 6-311++G(d,p) basis set by Gaussian 09 W program, for the first time. The assignments of the vibrational frequencies were performed by potential energy distribution (PED) analysis by using VEDA 4 program. The theoretical optimized geometric parameters and vibrational frequencies were compared with the corresponding experimental data, and they were seen to be in a good agreement with each other. Also, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies were found.

  15. Real-time visualization of the vibrational wavepacket dynamics in electronically excited pyrimidine via femtosecond time-resolved photoelectron imaging

    Science.gov (United States)

    Li, Shuai; Long, Jinyou; Ling, Fengzi; Wang, Yanmei; Song, Xinli; Zhang, Song; Zhang, Bing

    2017-07-01

    The vibrational wavepacket dynamics at the very early stages of the S1-T1 intersystem crossing in photoexcited pyrimidine is visualized in real time by femtosecond time-resolved photoelectron imaging and time-resolved mass spectroscopy. A coherent superposition of the vibrational states is prepared by the femtosecond pump pulse at 315.3 nm, resulting in a vibrational wavepacket. The composition of the prepared wavepacket is directly identified by a sustained quantum beat superimposed on the parent-ion transient, possessing a frequency in accord with the energy separation between the 6a1 and 6b2 states. The dephasing time of the vibrational wavepacket is determined to be 82 ps. More importantly, the variable Franck-Condon factors between the wavepacket components and the dispersed cation vibrational levels are experimentally illustrated to identify the dark state and follow the energy-flow dynamics on the femtosecond time scale. The time-dependent intensities of the photoelectron peaks originated from the 6a1 vibrational state exhibit a clear quantum beating pattern with similar periodicity but a phase shift of π rad with respect to those from the 6b2 state, offering an unambiguous picture of the restricted intramolecular vibrational energy redistribution dynamics in the 6a1/6b2 Fermi resonance.

  16. Mode shape and natural frequency identification for seismic analysis from background vibration

    International Nuclear Information System (INIS)

    Bhan, S.; Wozniak, Z.

    1986-10-01

    Background vibration in a CANDU plant can be used to determine the dynamic characteristics of major items of equipment, such as calandria, the fuelling machines and the primary heat transport pumps. These dynamic characteristics can then be used to verify the seismic response of the equipment which, at present, is based on theoretical models only. The feasibility and basic theory of this new approach (which uses accelerations measured at several points on a structure and does not require knowledge of the source of excitation) was established in Phase I of the study. This report is based on Phase II in which the methods of analysis developed in Phase I were improved and verified experimentally. A Fast Fourier Transform (FFT) algorithm was incorporated and an interactive curve fitting technique was developed to obtain the dynamic characteristics in the form of natural frequencies, mode shapes and damping ratios. The method is now available for use at a CANDU plant

  17. Improved Laser Vibration Radar

    National Research Council Canada - National Science Library

    Hilaire, Pierre

    1998-01-01

    .... This thesis reconfigured an existing CO2 laboratory laser radar system that is capable of measuring the frequencies of vibration of a simulated target into a more compact and rugged form for field testing...

  18. Vibrational Spectral Studies of Gemfibrozil

    Science.gov (United States)

    Benitta, T. Asenath; Balendiran, G. K.; James, C.

    2008-11-01

    The Fourier Transform Raman and infrared spectra of the crystallized drug molecule 5-(2,5-Dimethylphenoxy)-2,2-dimethylpentanoic acid (Gemfibrozil) have been recorded and analyzed. Quantum chemical computational methods have been employed using Gaussian 03 software package based on Hartree Fock method for theoretically modeling the grown molecule. The optimized geometry and vibrational frequencies have been predicted. Observed vibrational modes have been assigned with the aid of normal coordinate analysis.

  19. Design, Simulation, and Optimization of a Frequency-Tunable Vibration Energy Harvester That Uses a Magnetorheological Elastomer

    Directory of Open Access Journals (Sweden)

    Wan Sun

    2015-01-01

    Full Text Available This study focuses on the design, simulation, and load power optimization for the development of a novel frequency-tunable electromagnetic vibrational energy harvester. The unique characteristic of a magnetorheological elastomer (MRE is utilized, that the shear modulus can be varied by changing the strength of an applied magnetic field. The electromagnetic energy harvester is fabricated, the external electric circuit is connected, and the performance is evaluated through a series of experiments. The resonant frequencies and the parasitic damping constant are measured experimentally for different tuning magnet gap distances, which validate the application of the MRE to the development of a frequency-tunable energy harvesting system. The harvested energy of the system is measured by the voltage across the load resistor. The maximum load power is attained by optimizing the external circuit connected to the coil system. The analysis results are presented for harvesting the maximum load power in terms of the coil parameters and external circuit resistance. The optimality of the load resistance is validated by comparing the analytical results with experimental results. The optimal load resistances under various resonance frequencies are also found for the design and composition of the optimal energy harvesting circuit of the energy harvester system.

  20. Bivariate frequency analysis of rainfall intensity and duration for urban stormwater infrastructure design

    Science.gov (United States)

    Jun, Changhyun; Qin, Xiaosheng; Gan, Thian Yew; Tung, Yeou-Koung; De Michele, Carlo

    2017-10-01

    This study presents a storm-event based bivariate frequency analysis approach to determine design rainfalls in which, the number, intensity and duration of actual rainstorm events were considered. To derive more realistic design storms, the occurrence probability of an individual rainstorm event was determined from the joint distribution of storm intensity and duration through a copula model. Hourly rainfall data were used at three climate stations respectively located in Singapore, South Korea and Canada. It was found that the proposed approach could give a more realistic description of rainfall characteristics of rainstorm events and design rainfalls. As results, the design rainfall quantities from actual rainstorm events at the three studied sites are consistently lower than those obtained from the conventional rainfall depth-duration-frequency (DDF) method, especially for short-duration storms (such as 1-h). It results from occurrence probabilities of each rainstorm event and a different angle for rainfall frequency analysis, and could offer an alternative way of describing extreme rainfall properties and potentially help improve the hydrologic design of stormwater management facilities in urban areas.

  1. PREFACE: Vibrations at surfaces Vibrations at surfaces

    Science.gov (United States)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of

  2. Linear response of vibrated granular systems to sudden changes in the vibration intensity

    International Nuclear Information System (INIS)

    Brey, J. Javier; Prados, A.

    2001-01-01

    The short-term memory effects recently observed in vibration-induced compaction of granular materials are studied. It is shown that they can be explained by means of quite plausible hypothesis about the mesoscopic description of the evolution of the system. The existence of a critical time separating regimes of 'anomalous' and 'normal' responses is predicted. A simple model fitting into the general framework is analyzed in the detail. The relationship between this paper and previous studies is discussed

  3. Surface vibrational modes in disk-shaped resonators.

    Science.gov (United States)

    Dmitriev, A V; Gritsenko, D S; Mitrofanov, V P

    2014-03-01

    The natural frequencies and distributions of displacement components for the surface vibrational modes in thin isotropic elastic disks are calculated. In particular, the research is focused on even solutions for low-lying resonant vibrations with large angular wave numbers. Several families of modes are found which are interpreted as modified surface modes of an infinitely long cylinder and Lamb modes of a plate. The results of calculation are compared with the results of the experimental measurements of vibrational modes generated by means of resonant excitation in duraluminum disk with radius of ≈90 mm and thickness of 16 mm in the frequency range of 130-200 kHz. An excellent agreement between the calculated and measured frequencies is found. Measurements of the structure of the resonant peaks show splitting of some modes. About a half of the measured modes has splitting Δfsplit/fmode at the level of the order of 10(-5). The Q-factors of all modes measured in vacuum lie in the interval (2…3)×10(5). This value is typical for duraluminum mechanical resonators in the ultrasonic frequency range. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Vibration behavior of the artificial barrier system

    Energy Technology Data Exchange (ETDEWEB)

    Mikoshiba, Tadashi; Ogawa, Nobuyuki; Nakamura, Izuru [National Research Inst. for Earth sceince and Disaster Prevention (Japan)

    2000-02-01

    This study aims at production of a mimic specimen of artificial barrier, experimental elucidation of influence of seismic motion due to a vibration experiment on the artificial barrier system, and establishment of an evaluating method on its long-term behavior. The study has been carried out under a cooperative study of the National Research Institute for Earth Science and Disaster Prevention and the Japan Nuclear Cycle Development Institute. In 1998 fiscal year, an artificial barrier specimen initiated by crosscut road was produced, and their random wave and actual seismic wave vibrations were carried out to acquire their fundamental data. As a result of the both vibrations, it was found that in a Case 2 specimen of which buffer material was swelled by poured water, the material was integrated with a mimic over-pack to vibrate under judgement of eigen-frequency, maximum acceleration ratio, and so forth on the test results. And, in a Case 1 specimen, it was thought that the mimic over-pack showed an extreme non-linear performance (soft spring) because of reducing eigen-frequency with increase of its vibration level. (G.K.)

  5. Vibration behavior of the artificial barrier system

    International Nuclear Information System (INIS)

    Mikoshiba, Tadashi; Ogawa, Nobuyuki; Nakamura, Izuru

    2000-01-01

    This study aims at production of a mimic specimen of artificial barrier, experimental elucidation of influence of seismic motion due to a vibration experiment on the artificial barrier system, and establishment of an evaluating method on its long-term behavior. The study has been carried out under a cooperative study of the National Research Institute for Earth Science and Disaster Prevention and the Japan Nuclear Cycle Development Institute. In 1998 fiscal year, an artificial barrier specimen initiated by crosscut road was produced, and their random wave and actual seismic wave vibrations were carried out to acquire their fundamental data. As a result of the both vibrations, it was found that in a Case 2 specimen of which buffer material was swelled by poured water, the material was integrated with a mimic over-pack to vibrate under judgement of eigen-frequency, maximum acceleration ratio, and so forth on the test results. And, in a Case 1 specimen, it was thought that the mimic over-pack showed an extreme non-linear performance (soft spring) because of reducing eigen-frequency with increase of its vibration level. (G.K.)

  6. Analysis of molecular structure and vibrational spectra of hexadecyl (cetyl) trimethylammonium brode (CTAB)

    International Nuclear Information System (INIS)

    Goekce, H.; Bahceli, S.

    2010-01-01

    FT-IR and Raman spectra of CTAB [C 1 6H 3 3N(CH 3 ) 3 ] + Br - have been experimentally recorded in the region 550-4000 cm - 1 and 400-3100 cm - 1, respectively. The molecular geometry and vibrational frequencies of CTAB in the ground state have been calculated by using ab initio Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods with the 6-31+G(d,p) basis set. The obtained optimized geometric parameters (bond lengths and bond angles) and vibrational frequencies were in very good agreement with the experimental data. The comparisons of the observed fundamental vibrational frequencies and calculated results for the fundamental vibrational frequencies of CTAB shows that the scaled B3LYP method is superior compared to the scaled HF method.

  7. Coupled vibration study of the blade of the flexible wind wheel with the low-speed shafting

    International Nuclear Information System (INIS)

    Su, L Y; Zhao, R Z; Liu, H; Meng, Z R

    2013-01-01

    Movement and deformation of flexible wind wheel has a profound effect on dynamics of the low-speed shafting in Megawatt wind turbine. The paper is based on the power production1.2 MW wind turbine, vibration characteristics of elastic wind wheel with the low-speed shafting were studied. In order to obtain the finite element model, the author created a physical model of this coupled system and used the minimum energy principle to simplify the model. While its single blade simplified as cantilever. Using modal superposition method for solving the coupled system model. Structural mechanics equations were used to solve the simple blade finite element model. Analyzing the natural frequency of the coupled system and the stress diagram, the results indicate that in the coupling system, low frequency vibration occurs in the low-speed shaft bearing, while the high-frequency vibration happens on wind turbine blades. In the low-frequency vibration process, blades vibration and low-speed shaft vibration there is a strong correlation. Contrast inherent frequency of the wind wheel with natural frequency of a single blade, the results show that the frequency of the wind wheel slightly less than it in the single blade

  8. Insights from random vibration analyses using multiple earthquake components

    International Nuclear Information System (INIS)

    DebChaudhury, A.; Gasparini, D.A.

    1981-01-01

    The behavior of multi-degree-of-freedom systems subjected to multiple earthquake components is studied by the use of random vibration dynamic analyses. A linear system which has been decoupled into modes and has both translational and rotational degrees of freedom is analyzed. The seismic excitation is modelled as a correlated or uncorrelated, vector-valued, non-stationary random process having a Kanai-Tajimi type of frequency content. Non-stationarity is achieved by using a piece wise linear strength function. Therefore, almost any type of evolution and decay of an earthquake may be modelled. Also, in general, the components of the excitation have different frequency contents and strength functions; i.e. intensities and durations and the correlations between components can vary with time. A state-space, modal, random vibration approach is used. Exact analytical expressions for both the state transition matrix and the evolutionary modal covariance matrix are utilized to compute time histories of modal RMS responses. Desired responses are then computed by modal superposition. Specifically, relative displacement, relative velocity and absolute acceleration responses are studied. An important advantage of such analyses is that RMS responses vary smoothly in time therefore large time intervals may be used to generate response time histories. The modal superposition is exact; that is, all cross correlation terms between modal responses are included. (orig./RW)

  9. Vibrational polarizabilities of hydrogen-bonded water

    International Nuclear Information System (INIS)

    Torii, Hajime

    2013-01-01

    Highlights: ► Vibrational polarizabilities of hydrogen-bonded water are analyzed theoretically. ► Total vibrational polarizability is (at least) comparable to the electronic one. ► Molecular translations contribute to the vibrational polarizability below 300 cm −1 . ► Intermolecular charge fluxes along H bonds are induced by molecular translations. ► The results are discussed in relation to the observed dielectric properties. - Abstract: The vibrational polarizabilities and the related molecular properties of hydrogen-bonded water are analyzed theoretically, taking the case of (water) 30 clusters as an example case. It is shown that some off-diagonal dipole derivatives are large for the translations of incompletely hydrogen-bonded molecules, and this is reasonably explained by the scheme of intermolecular charge fluxes induced along hydrogen bonds. In total, because of these intermolecular charge fluxes, molecular translations give rise to the vibrational polarizability of 2.8–3.3 a 0 3 per molecule, which is as large as about 40% of the electronic polarizability, mainly in the frequency region below 300 cm −1 . Adding the contributions of the molecular rotations (librations) and the translation–rotation cross term, the total polarizability (electronic + vibrational) at ∼100 cm −1 is slightly larger than the double of that at >4000 cm −1 . The relation of these results to some observed time- and frequency-dependent dielectric properties of liquid water is briefly discussed

  10. Analysis of the spectrum distribution of oscillation amplitudes of the concrete mix at shock vibration molding

    Directory of Open Access Journals (Sweden)

    Sharapov Rashid

    2017-01-01

    Full Text Available In the production of concrete structures widespread shaking tables of various designs. The effectiveness of vibroforming concrete items largely depends on the choice of rational modes of vibroeffect to the compacting mixture. The article discusses the propagation of a wave packet in the concrete mixture under shock and vibration molding. Studies have shown that the spectrum of a wave packet contains a large number of harmonics. The main parameter influencing the amplitude-frequency spectrum is the stiffness of elastic gaskets between mold and forming machine vibrating table. By varying the stiffness of the elastic gaskets can widely change the spectrum of the oscillations propagating in the concrete mix. Thus, it is possible to adjust the intensity of the process of vibroforming.

  11. Control of pipe vibrations; Schwingungsminderung bei Rohrleitungen

    Energy Technology Data Exchange (ETDEWEB)

    Sinambari, G.R. [FH Bingen, Fachrichtung Umweltschutz, und IBS Ingenieurbuero fuer Schall- und Schwingungstechnik GmbH, Frankenthal (Germany); Thorn, U. [IBS Ingenieurbuero fuer Schall- und Schwingungstechnik GmbH, Frankenthal (Germany)

    2005-06-01

    Following commissioning of a new vacuum system for the refinery of MiRO Mineraloelraffinerie Oberrhein GmbH and Co. KG, vibrations occurred in the furnace exhaust pipes. As these had to be regarded as critical for the fatigue strength of the pipes, the pipes' vibration response in the critical frequency range was investigated immediately by means of a vibration analysis, and appropriate measures for vibration control were elaborated. All investigations, and the installation of the hydraulic vibration dampers, took place with the system operating. The effectiveness of the measures taken was checked by means of measurements following installation. The measures succeeded in attenuating the vibrations to a level at which, empirically, damage need no longer be expected. This paper illustrates the procedure for developing the vibration control measures and the essential results of the investigations. (orig.)

  12. Vibrational modes of hydraulic fractures: Inference of fracture geometry from resonant frequencies and attenuation

    Science.gov (United States)

    Lipovsky, Bradley P.; Dunham, Eric M.

    2015-02-01

    Oscillatory seismic signals arising from resonant vibrations of hydraulic fractures are observed in many geologic systems, including volcanoes, glaciers and ice sheets, and hydrocarbon and geothermal reservoirs. To better quantify the physical dimensions of fluid-filled cracks and properties of the fluids within them, we study wave motion along a thin hydraulic fracture waveguide. We present a linearized analysis, valid at wavelengths greater than the fracture aperture, that accounts for quasi-static elastic deformation of the fracture walls, as well as fluid viscosity, inertia, and compressibility. In the long-wavelength limit, anomalously dispersed guided waves known as crack or Krauklis waves propagate with restoring force from fracture wall elasticity. At shorter wavelengths, the waves become sound waves within the fluid channel. Wave attenuation in our model is due to fluid viscosity, rather than seismic radiation from crack tips or fracture wall roughness. We characterize viscous damping at both low frequencies, where the flow is always fully developed, and at high frequencies, where the flow has a nearly constant velocity profile away from viscous boundary layers near the fracture walls. Most observable seismic signals from resonating fractures likely arise in the boundary layer crack wave limit, where fluid-solid coupling is pronounced and attenuation is minimal. We present a method to estimate the aperture and length of a resonating hydraulic fracture using both the seismically observed quality factor and characteristic frequency. Finally, we develop scaling relations between seismic moment and characteristic frequency that might be useful when interpreting the statistics of hydraulic fracture events.

  13. Quantitative infrared and near-infrared gas-phase spectra for pyridine: Absolute intensities and vibrational assignments

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, T. J.; Aker, P. M.; Scharko, N. K.; Williams, S. D.

    2018-02-01

    Using vetted methods for generating quantitative absorption reference data, broadband infrared and near-infrared spectra (total range 11,000 – 600 cm-1) of pyridine vapor were recorded at 0.1 cm-1 spectral resolution, with the analyte thermostatted at 298 K and pressure-broadened to 1 atmosphere using N2 ballast gas. The quantitative spectrum is reported for the first time, and we have re-assigned some of the 27 fundamental modes. Fundamental assignments were confirmed by IR vapor phase band shapes, FT-Raman measurements and comparison with previous analyses. For the 760-Torr vapor-phase IR data several bands show resolved peaks (Q-branches). We have also assigned for the first time hundreds of combination and overtone bands in the mid- and near-IR. All assignments were made via comparison to theoretically calculated frequencies and intensities: The frequencies were computed with Gaussian03 with the anharmonic option, using MP2 and the ccpvtz basis set. The intensities were taken from a VSCF calculation in GAMESS using Hartree-Fock (for overtones and combination bands) or from the harmonic MP2 for fundamentals. Overtone and combination band harmonic and anharmonic frequencies, as well as intensities were also calculated using the CFOUR program. It is seen in the NIR spectrum near 6000 cm-1 that the very strong bands arise from the C-H first overtones, whereas only much weaker bands are observed for combination bands of C-H stretching modes. Certain features are discussed for their potential utility for atmospheric monitoring.

  14. Method and apparatus for vibrating a substrate during material formation

    Science.gov (United States)

    Bailey, Jeffrey A [Richland, WA; Roger, Johnson N [Richland, WA; John, Munley T [Benton City, WA; Walter, Park R [Benton City, WA

    2008-10-21

    A method and apparatus for affecting the properties of a material include vibrating the material during its formation (i.e., "surface sifting"). The method includes the steps of providing a material formation device and applying a plurality of vibrations to the material during formation, which vibrations are oscillations having dissimilar, non-harmonic frequencies and at least two different directions. The apparatus includes a plurality of vibration sources that impart vibrations to the material.

  15. Vibrational relaxation of a triatomic molecular impurity: D2O in vitreous As2S3

    International Nuclear Information System (INIS)

    Rella, C.W.; Schwettman, H.A.; Engholm, J.R.

    1995-01-01

    Measurements of the relaxation of the D 2 O stretch mode in vitreous As 2 S 3 are presented. Because the bending mode of the molecule offers an intra-molecular decay channel for the stretch mode, the decay scheme of the D 2 O molecule is more complex than that of diatomic molecules. The asymmetric stretch mode of D 2 O has a frequency of 2680 cm -1 . To study the relaxation of this mode we applied a pump-probe technique, using intense psec; pulses of the Stanford Free Electron Laser. Due to the small cross-section of the vibrational mode, successful efforts were made to improve the signal to noise ratio by using a laser stabilization system and a tightly focused beam to increase the intensity, by averaging the signal with a kHz repetition rate and by using samples with an optimized D 2 O concentration. A rapid relaxation rate on the order of 5 x 10 9 sec -1 at low temperature is found that increases with temperature. Recalling that the bending mode of the D 2 O molecule has a frequency of 1170 cm -1 , one would expect a decay in a third order process, involving two quanta of the bending mode plus a vibrational host quanta with a frequency of 340 cm -1 , which coincides with a fundamental frequency of the pyramidal building blocks of the glassy As 2 S 3 host. Instead, we find from the temperature dependence of the relaxation rate that the D 2 O stretching mode relaxes in a higher order process. This indicates that the relaxation dynamics of small molecules is more complex than generally assumed

  16. Off-resonant vibrational excitation: Orientational dependence and spatial control of photofragments

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    2000-01-01

    Off-resonant and resonant vibrational excitation with short intense infrared (IR) laser pulses creates localized oscillating wave packets, but differs by the efficiency of the excitation and surprisingly by the orientational dependence. Orientational selectivity of the vibrational excitation...... of randomly oriented heteronuclear diatomic molecules can be obtained under simultaneous irradiation by a resonant and an off-resonant intense IR laser pulse: Molecules with one initial orientation will be vibrationally excited, while those with the opposite orientation will be at rest. The orientation-dependent...... distribution. (C) 2000 American Institute of Physics....

  17. Adaptive techniques for diagnostics of vibrating structures

    International Nuclear Information System (INIS)

    Skormin, V.A.; Sankar, S.

    1983-01-01

    An adaptive diagnostic procedure for vibrating structures based on correspondence between current estimates of stiffness matrix and structure status is proposed. Procedure employs adaptive mathematical description of the vibrating structure in frequency domain, statistical techniques for detection and location of changes of structure properties, 'recognition' and prediction of defects. (orig.)

  18. Comparative studies of perceived vibration strength for commercial mobile phones.

    Science.gov (United States)

    Lee, Heow Pueh; Lim, Siak Piang

    2014-05-01

    A mobile phone, also known as cell phone or hand phone, is among the most popular electrical devices used by people all over the world. The present study examines the vibration perception of mobile phones by co-relating the relevant design parameters such as excitation frequency, and size and mass of mobile phones to the vibration perception survey by volunteers. Five popular commercially available mobile phone models were tested. The main findings for the perception surveys were that higher vibration frequency and amplitude of the peak acceleration would result in stronger vibration perception of the mobile phones. A larger contact surface area with the palms and figures, higher peak acceleration and the associated larger peak inertia force may be the main factors for the relatively higher vibration perception. The future design for the vibration alert of the mobile phones is likely to follow this trend. Copyright © 2013 Elsevier Ltd and The Ergonomics Society. All rights reserved.

  19. Bias-Flip Technique for Frequency Tuning of Piezo-Electric Energy Harvesting Devices

    Directory of Open Access Journals (Sweden)

    Jianguo Ma

    2013-06-01

    Full Text Available Devices that harvest electrical energy from mechanical vibrations have the problem that the frequency of the source vibration is often not matched to the resonant frequency of the energy harvesting device. Manufacturing tolerances make it difficult to match the Energy Harvesting Device (EHD resonant frequency to the source vibration frequency, and the source vibration frequency may vary with time. Previous work has recognized that it is possible to tune the resonant frequency of an EHD using a tunable, reactive impedance at the output of the device. The present paper develops the theory of electrical tuning, and proposes the Bias-Flip (BF technique, to implement this tunable, reactive impedance.

  20. Conformational Stability, Structural Parameters And Vibrational Assignments of Allantoin

    International Nuclear Information System (INIS)

    Haman, S.

    2008-01-01

    Allantoin 2,5-Dioxo-4-imidazolinyl) urea , the diureide of glyoxylic acid, is a crystallisable oxidation product of uric acid found in allantoic and amniotic fluids, in fetal urine and in many plants. It is a healing, moisturizing, soothing and anti-irritating, keratolytic and non-toxic agent useful in dermatological, cosmetic and veterinary preparation. The optimized geometries and energies of the low-energy conformers of allantoin have been calculated using density functional theory (Daft) method. The calculations were performed with Beck's nonlocal three-parameter hybrid functional in combination with the Lee, Yang, and Parr correlation functional (By-play) using the 6-311++G(d,p) basis set. We calculated the infrared frequencies and intensities of the most stable conformers in order to assist in the assignment of the vibrational bands in the experimental spectrum. The B3LYP/6-311+G(d,p) harmonic force constants were scaled by applying the scaled quantum mechanical force field (SQM) technique. The calculated vibrational spectra were interpreted and band assignments were reported