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.

Natural bond orbital analysis, electronic structure and vibrational spectral analysis of N-(4-hydroxyl phenyl) acetamide: A density functional theory

Science.gov (United States)

Govindasamy, P.; Gunasekaran, S.; Ramkumaar, G. R.

2014-09-01

The Fourier transform infrared (FT-IR) and FT-Raman spectra of N-(4-hydroxy phenyl) acetamide (N4HPA) of painkiller agent were recorded in the region 4000-450 cm-1 and 4000-50 cm-1 respectively. Density functional theory (DFT) has been used to calculate the optimized geometrical parameter, atomic charges, and vibrational wavenumbers and intensity of the vibrational bands. The computed vibrational wave numbers were compared with the FT-IR and FT-Raman experimental data. The computational calculations at DFT/B3LYP level with 6-31G(d,p), 6-31++G(d,p), 6-311G(d,p) and 6-311++G(d,p) basis sets. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes calculated using Vibrational energy distribution analysis (VEDA 4) program. The oscillator’s strength calculated by TD-DFT and N4HPA is approach complement with the experimental findings. The NMR chemical shifts 13C and 1H were recorded and calculated using the gauge independent atomic orbital (GIAO) method. The molecular electrostatic potential (MESP) and electron density surfaces of the molecule were constructed. The Natural charges and intermolecular contacts have been interpreted using Natural Bond orbital (NBO) analysis the HOMO-LUMO energy gap has been calculated. The thermodynamic properties like entropy, heat capacity and zero vibrational energy have been calculated.

Spectral analysis of allogeneic hydroxyapatite powders

Science.gov (United States)

Timchenko, P. E.; Timchenko, E. V.; Pisareva, E. V.; Vlasov, M. Yu; Red'kin, N. A.; Frolov, O. O.

2017-01-01

In this paper we discuss the application of Raman spectroscopy to the in vitro analysis of the hydroxyapatite powder samples produced from different types of animal bone tissue during demineralization process at various acid concentrations and exposure durations. The derivation of the Raman spectrum of hydroxyapatite is attempted by the analysis of the pure powders of its known constituents. Were experimentally found spectral features of hydroxyapatite, based on analysis of the line amplitude at wave numbers 950-965 cm-1 ((PO4)3- (ν1) vibration) and 1065-1075 cm-1 ((CO3)2-(ν1) B-type replacement). Control of physicochemical properties of hydroxyapatite was carried out by Raman spectroscopy. Research results are compared with an infrared Fourier spectroscopy.

Spectral analysis of allogeneic hydroxyapatite powders

International Nuclear Information System (INIS)

Timchenko, P E; Timchenko, E V; Pisareva, E V; Vlasov, M Yu; Red’kin, N A; Frolov, O O

2017-01-01

In this paper we discuss the application of Raman spectroscopy to the in vitro analysis of the hydroxyapatite powder samples produced from different types of animal bone tissue during demineralization process at various acid concentrations and exposure durations. The derivation of the Raman spectrum of hydroxyapatite is attempted by the analysis of the pure powders of its known constituents. Were experimentally found spectral features of hydroxyapatite, based on analysis of the line amplitude at wave numbers 950-965 cm -1 ((PO 4 ) 3- (ν 1 ) vibration) and 1065-1075 cm -1 ((CO 3 ) 2- (ν 1 ) B-type replacement). Control of physicochemical properties of hydroxyapatite was carried out by Raman spectroscopy. Research results are compared with an infrared Fourier spectroscopy. (paper)

The ABRAVIBE toolbox for teaching vibration analysis and structural dynamics

DEFF Research Database (Denmark)

Brandt, A.

2013-01-01

, a MATLAB toolbox (the ABRAVIBE toolbox) has been developed as an accompanying toolbox for the recent book "Noise and Vibration Analysis" by the author. This free, open software, published under GNU Public License, can be used with GNU Octave, if an entirely free software platform is wanted, with a few...... functional limitations. The toolbox includes functionality for simulation of mechanical models as well as advanced analysis such as time series analysis, spectral analysis, frequency response and correlation function estimation, modal parameter extraction, and rotating machinery analysis (order tracking...

Suspension system vibration analysis with regard to variable type ability to smooth road irregularities

Science.gov (United States)

Rykov, S. P.; Rykova, O. A.; Koval, V. S.; Makhno, D. E.; Fedotov, K. V.

2018-03-01

The paper aims to analyze vibrations of the dynamic system equivalent of the suspension system with regard to tyre ability to smooth road irregularities. The research is based on static dynamics for linear systems of automated control, methods of correlation, spectral and numerical analysis. Input of new data on the smoothing effect of the pneumatic tyre reflecting changes of a contact area between the wheel and road under vibrations of the suspension makes the system non-linear which requires using numerical analysis methods. Taking into account the variable smoothing ability of the tyre when calculating suspension vibrations, one can approximate calculation and experimental results and improve the constant smoothing ability of the tyre.

Study of core support barrel vibration monitoring using ex-core neutron noise analysis and fuzzy logic algorithm

International Nuclear Information System (INIS)

Christian, Robby; Song, Seon Ho; Kang, Hyun Gook

2015-01-01

The application of neutron noise analysis (NNA) to the ex-core neutron detector signal for monitoring the vibration characteristics of a reactor core support barrel (CSB) was investigated. Ex-core flux data were generated by using a nonanalog Monte Carlo neutron transport method in a simulated CSB model where the implicit capture and Russian roulette technique were utilized. First and third order beam and shell modes of CSB vibration were modeled based on parallel processing simulation. A NNA module was developed to analyze the ex-core flux data based on its time variation, normalized power spectral density, normalized cross-power spectral density, coherence, and phase differences. The data were then analyzed with a fuzzy logic module to determine the vibration characteristics. The ex-core neutron signal fluctuation was directly proportional to the CSB's vibration observed at 8Hz and15Hzin the beam mode vibration, and at 8Hz in the shell mode vibration. The coherence result between flux pairs was unity at the vibration peak frequencies. A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations.

Synthesis, XRD single crystal structure analysis, vibrational spectral analysis, molecular dynamics and molecular docking studies of 2-(3-methoxy-4-hydroxyphenyl) benzothiazole

Science.gov (United States)

Sarau Devi, A.; Aswathy, V. V.; Sheena Mary, Y.; Yohannan Panicker, C.; Armaković, Stevan; Armaković, Sanja J.; Ravindran, Reena; Van Alsenoy, C.

2017-11-01

The vibrational spectra and corresponding vibrational assignments of 2-(3-methoxy-4-hydroxyphenyl)benzothiazole is reported. Single crystal XRD data of the title compound is reported and the orientation of methoxy group is cis to nitrogen atom of the thiazole ring. The phenyl ring breathing modes of the title compound are assigned at 1042 and 731 cm-1 theoretically. The charge transfer within the molecule is studied using frontier molecular orbital analysis. The chemical reactivity descriptors are calculated theoretically. The NMR spectral data predicted theoretically are in good agreement with the experimental data. The strong negative region spread over the phenyl rings, nitrogen atom and oxygen atom of the hydroxyl group in the MEP plot is due to the immense conjugative and hyper conjugative resonance charge delocalization of π-electrons. Molecule sites prone to electrophilic attacks have been determined by analysis of ALIE surfaces, while Fukui functions provided further insight into the local reactivity properties of title molecule. Autoxidation properties have been investigated by calculation of bond dissociation energies (BDEs) of hydrogen abstraction, while BDEs of the rest of the single acyclic bonds were valuable for the further investigation of degradation properties. Calculation of radial distribution functions was performed in order to determine which atoms of the title molecule have pronounced interactions with water molecules. The title compound forms a stable complex with aryl hydrocarbon receptor and can be a lead compound for developing new anti-tumor drug. Antimicrobial properties of the title compound was screened against one bacterial culture Escherchia coli and four fungal cultures viz., Aspergillus niger, Pencillum chrysogenum, Saccharomyces cerevisiae and Rhyzopus stolonifer.

High-speed Vibrational Imaging and Spectral Analysis of Lipid Bodies by Compound Raman Microscopy

OpenAIRE

Slipchenko, Mikhail N.; Le, Thuc T.; Chen, Hongtao; Cheng, Ji-Xin

2009-01-01

Cells store excess energy in the form of cytoplasmic lipid droplets. At present, it is unclear how different types of fatty acids contribute to the formation of lipid-droplets. We describe a compound Raman microscope capable of both high-speed chemical imaging and quantitative spectral analysis on the same platform. We use a picosecond laser source to perform coherent Raman scattering imaging of a biological sample and confocal Raman spectral analysis at points of interest. The potential of t...

Vibration analysis of cooling system of upgraded PARR-1: (primary pumps)

International Nuclear Information System (INIS)

Ayazuddin, S.K.; Baig, R.; Pervez, S.

1992-12-01

During the conversion and up gradation of PARR-1, major changes were made in the cooling system of the reactor with the addition of new heat exchanger assemblies and cooling tower. It was therefore, planned to perform vibration analysis on the cooling system to check proper installation and investigate any abnormality in the operation. As a first step, vibration measurements was made on the primary pumps PW-P1 and PW-P2. Power spectral density (PSD) or frequency spectrum of the signal produced from an accelerometer placed on the pump motor assembly was analysed to identify faults which are commonly found in rotating and reciprocating machinery such as unbalance, shaft misalignment and bearing instability. The root mean square (RMS) of the signal was compared with the vibration criterion chart to determine the operating condition of the pump motor assembly. The procedure used for the analysis and faults detected in the primary pump-motor system are discussed. 9 figs. (author)

Vibrational study and Natural Bond Orbital analysis of serotonin in monomer and dimer states by density functional theory

Science.gov (United States)

Borah, Mukunda Madhab; Devi, Th. Gomti

2018-06-01

The vibrational spectral analysis of Serotonin and its dimer were carried out using the Fourier Transform Infrared (FTIR) and Raman techniques. The equilibrium geometrical parameters, harmonic vibrational wavenumbers, Frontier orbitals, Mulliken atomic charges, Natural Bond orbitals, first order hyperpolarizability and some optimized energy parameters were computed by density functional theory with 6-31G(d,p) basis set. The detailed analysis of the vibrational spectra have been carried out by computing Potential Energy Distribution (PED, %) with the help of Vibrational Energy Distribution Analysis (VEDA) program. The second order delocalization energies E(2) confirms the occurrence of intramolecular Charge Transfer (ICT) within the molecule. The computed wavenumbers of Serotonin monomer and dimer were found in good agreement with the experimental Raman and IR values.

Vibrational spectra and natural bond orbital analysis of organic crystal L-prolinium picrate

Science.gov (United States)

Edwin, Bismi; Amalanathan, M.; Hubert Joe, I.

2012-10-01

Vibrational spectral analysis and quantum chemical computations based on density functional theory (DFT) have been performed on the organic crystal L-prolinium picrate (LPP). The equilibrium geometry, various bonding features and harmonic vibrational wavenumbers of LPP have been investigated using B3LYP method. The calculated molecular geometry has been compared with the experimental data. The detailed interpretation of the vibrational spectra has been carried out with the aid of VEDA 4 program. The various intramolecular interactions confirming the biological activity of the compound have been exposed by natural bond orbital analysis. The distribution of Mulliken atomic charges and bending of natural hybrid orbitals associated with hydrogen bonding also reflects the presence of intramolecular hydrogen bonding thereby enhancing bioactivity. The analysis of the electron density of HOMO and LUMO gives an idea of the delocalization and low value of energy gap indicates electron transport in the molecule and thereby bioactivity. Vibrational analysis reveals the presence of strong O-H⋯O and N-H⋯O interaction between L-prolinium and picrate ions providing evidence for the charge transfer interaction between the donor and acceptor groups and is responsible for its bioactivity.

Wavelet and Spectral Analysis of Some Selected Problems in Reactor Diagnostics

Energy Technology Data Exchange (ETDEWEB)

Sunde, Carl

2004-12-01

Both spectral and wavelet analysis were successfully used in various diagnostic problems involving non-stationary core processes in nuclear power reactors. Three different problems were treated: two-phase flow identification, detector tube impacting and core-barrel vibrations. The first two problems are of non-stationary nature, whereas the last one is not. In the first problem, neutron radiographic and visible light images of four different vertical two-phase flow regimes, bubbly, slug, chum and annular flow, were analysed and classified with a neuro-wavelet algorithm. The algorithm consists of a wavelet part, using the 2-D discrete wavelet transform and of an artificial neural network. It classifies the different flow regimes with up to 99% efficiency. Detector tubes in a Boiling Water Reactor may execute vibrations and may also impact on nearby fuel-assemblies. Signals from in-core neutron detectors in Ringhals-1 were analysed, for detection of impacting, with both a classical spectral method and wavelet-based methods. The wavelet methods include both the discrete and the continuous 1-D wavelet transform. It was found that there is agreement between the different methods as well as with visual inspections made during the outage at the plant. However, the wavelet technique has the advantage that it does not require expert judgement for the interpretation of the analysis. In the last part two analytical calculations of the neutron noise, induced by shell-mode core-barrel vibrations, were carried out. The results are in good agreement with calculations from a numerical simulator. An out-of-phase behaviour between in-core and ex-core positions was found, which is in agreement with earlier measurements from the Pressurised Water Reactor Ringhals-3. The results from these calculations are planned to be used when diagnosing the shell-mode core-barrel vibrations in an operating plant.

Wavelet and Spectral Analysis of Some Selected Problems in Reactor Diagnostics

International Nuclear Information System (INIS)

Sunde, Carl

2004-12-01

Both spectral and wavelet analysis were successfully used in various diagnostic problems involving non-stationary core processes in nuclear power reactors. Three different problems were treated: two-phase flow identification, detector tube impacting and core-barrel vibrations. The first two problems are of non-stationary nature, whereas the last one is not. In the first problem, neutron radiographic and visible light images of four different vertical two-phase flow regimes, bubbly, slug, chum and annular flow, were analysed and classified with a neuro-wavelet algorithm. The algorithm consists of a wavelet part, using the 2-D discrete wavelet transform and of an artificial neural network. It classifies the different flow regimes with up to 99% efficiency. Detector tubes in a Boiling Water Reactor may execute vibrations and may also impact on nearby fuel-assemblies. Signals from in-core neutron detectors in Ringhals-1 were analysed, for detection of impacting, with both a classical spectral method and wavelet-based methods. The wavelet methods include both the discrete and the continuous 1-D wavelet transform. It was found that there is agreement between the different methods as well as with visual inspections made during the outage at the plant. However, the wavelet technique has the advantage that it does not require expert judgement for the interpretation of the analysis. In the last part two analytical calculations of the neutron noise, induced by shell-mode core-barrel vibrations, were carried out. The results are in good agreement with calculations from a numerical simulator. An out-of-phase behaviour between in-core and ex-core positions was found, which is in agreement with earlier measurements from the Pressurised Water Reactor Ringhals-3. The results from these calculations are planned to be used when diagnosing the shell-mode core-barrel vibrations in an operating plant

Simultaneous analysis of rotational and vibrational-rotational spectra of DF and HF to obtain irreducible molecular constants for HF

International Nuclear Information System (INIS)

Horiai, Koui; Uehara, Hiromichi

2011-01-01

Graphical abstract: Available rotational and vibrational-rotational spectral lines of DF and HF are analyzed simultaneously using a non-Born-Oppenheimer effective Hamiltonian. Research highlights: → Simultaneous analysis of DF and HF spectral data. → Application of a non-Born-Oppenheimer effective Hamiltonian. → Twenty irreducible molecular constants for HF have been determined. - Abstract: Analytic expressions of corrections for the breakdown of the Born-Oppenheimer approximation to Dunham's Y ij with optimal parameters, i.e., determinable clusters of expansion coefficients, are applied to a data analysis of the rotational and vibrational-rotational transitions of HF reported in the literature. All the available spectral lines of the two isotopologues, DF and HF, are simultaneously fitted to a single set of molecular parameters of HF within experimental errors. Fitting of a data set of 595 spectral transitions for DF and HF has generated only 20 minimal independent parameter values, i.e., 'irreducible' molecular constants of HF, that are sufficient to precisely generate 82 Y ij coefficients and 144 band constants in total: 41 Y ij and 72 band constants each for DF and HF.

Digital analysis of vibrations

International Nuclear Information System (INIS)

Bohnstedt, H.J.; Walter, G.

1982-01-01

Vibrational measurements, e.g. on turbomachinery, can be evaluated rapidly and economically with the aid of a combination of the following instruments: a desk-top computer, a two-channel vector filter and a FFT spectral analyzer. This equipment combination is available within the Allianz Centre for Technology and has also been used for mobile, on-site investigations during the last year. It enables calculation and display of time functions, kinetic shaft orbits, displacement diagrams. Bode plots, polar-coordinate plots, cascade diagrams and histograms. (orig.) [de

Application of the random vibration approach in the seismic analysis of LMFBR structures - Benchmark calculations

International Nuclear Information System (INIS)

Preumont, A.; Shilab, S.; Cornaggia, L.; Reale, M.; Labbe, P.; Noe, H.

1992-01-01

This benchmark exercise is the continuation of the state-of-the-art review (EUR 11369 EN) which concluded that the random vibration approach could be an effective tool in seismic analysis of nuclear power plants, with potential advantages on time history and response spectrum techniques. As compared to the latter, the random vibration method provides an accurate treatment of multisupport excitations, non classical damping as well as the combination of high-frequency modal components. With respect to the former, the random vibration method offers direct information on statistical variability (probability distribution) and cheaper computations. The disadvantages of the random vibration method are that it is based on stationary results, and requires a power spectral density input instead of a response spectrum. A benchmark exercise to compare the three methods from the various aspects mentioned above, on one or several simple structures has been made. The following aspects have been covered with the simplest possible models: (i) statistical variability, (ii) multisupport excitation, (iii) non-classical damping. The random vibration method is therefore concluded to be a reliable method of analysis. Its use is recommended, particularly for preliminary design, owing to its computational advantage on multiple time history analysis

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.

Spectral response of crystalline acetanilide and N -methylacetamide: Vibrational self-trapping in hydrogen-bonded crystals

Science.gov (United States)

Edler, Julian; Hamm, Peter

2004-06-01

Femtosecond pump-probe and Fourier transform infrared spectroscopy is applied to compare the spectral response of the amide I band and the NH-stretching band of acetanilide (ACN) and N -methylacetamide (NMA), as well as their deuterated derivatives. Both molecules form hydrogen-bonded molecular crystals that are regarded to be model systems for polypeptides and proteins. The amide I bands of both ACN and NMA show a temperature-dependent sideband, while the NH bands are accompanied by a sequence of equidistantly spaced satellite peaks. These spectral anomalies are interpreted as a signature of vibrational self-trapping. Two different types of states can be identified in both crystals in the pump-probe signal: a delocalized free-exciton state and a set of localized self-trapped states. The phonons that mediate self-trapping in ACN and deuterated ACN are identified by their temperature dependence, confirming our previous results. The study shows that the substructure of the NH band in NMA (amide A and amide B bands) originates, at least partly, from vibrational self-trapping and not, as often assumed, from a Fermi resonance.

Numerical Modal Analysis of Vibrations in a Three-Phase Linear Switched Reluctance Actuator

Directory of Open Access Journals (Sweden)

José Salvado

2017-01-01

Full Text Available This paper addresses the problem of vibrations produced by switched reluctance actuators, focusing on the linear configuration of this type of machines, aiming at its characterization regarding the structural vibrations. The complexity of the mechanical system and the number of parts used put serious restrictions on the effectiveness of analytical approaches. We build the 3D model of the actuator and use finite element method (FEM to find its natural frequencies. The focus is on frequencies within the range up to nearly 1.2 kHz which is considered relevant, based on preliminary simulations and experiments. Spectral analysis results of audio signals from experimental modal excitation are also shown and discussed. The obtained data support the characterization of the linear actuator regarding the excited modes, its vibration frequencies, and mode shapes, with high potential of excitation due to the regular operation regimes of the machine. The results reveal abundant modes and harmonics and the symmetry characteristics of the actuator, showing that the vibration modes can be excited for different configurations of the actuator. The identification of the most critical modes is of great significance for the actuator’s control strategies. This analysis also provides significant information to adopt solutions to reduce the vibrations at the design.

Man-Induced Vibrations

DEFF Research Database (Denmark)

Jönsson, Jeppe; Hansen, Lars Pilegaard

1994-01-01

work has been done on the measurement of the exact load functions and related reponse analysis. A recent work using a spectral description has been performed by Per-Erik Erikson and includes a good literature survey. Bachmann and Ammann give a good overview of vibrations caused by human activity. Other...

N-propyl nitrate vibrational spectrum analysis using DFT B3LYP quantum-chemical method

Science.gov (United States)

Shaikhullina, R. M.; Hrapkovsky, G. M.; Shaikhullina, M. M.

2018-05-01

Calculation of a molecular structure, conformation and related vibrational spectra of the n- propyl nitrate C3H7NO3 was carried out by means of density functional theory (DFT) by employing the Gaussian 03 package. The molecular geometries were fully optimized by using the Becker's three-parameter hybrid exchange functional combined with the Lee–Yang–Parr correlation functional (B3LYP) and using the 6-31G(d) basis set. By scanning the dihedral angles around C-O and C-C bonds, five energetically most favorable conformers of n-propyl nitrate - TG, TT, GT, GG and G´G forms were found. Vibrational spectra of the most energetically favorable conformers were calculated. The comparative analysis of calculated and experimental spectra is carried out, the spectral features of the conformational state of n-propyl nitrate and the spectral effects of formation of intramolecular hydrogen bonds are established.

Machine Fault Detection Based on Filter Bank Similarity Features Using Acoustic and Vibration Analysis

Directory of Open Access Journals (Sweden)

Mauricio Holguín-Londoño

2016-01-01

Full Text Available Vibration and acoustic analysis actively support the nondestructive and noninvasive fault diagnostics of rotating machines at early stages. Nonetheless, the acoustic signal is less used because of its vulnerability to external interferences, hindering an efficient and robust analysis for condition monitoring (CM. This paper presents a novel methodology to characterize different failure signatures from rotating machines using either acoustic or vibration signals. Firstly, the signal is decomposed into several narrow-band spectral components applying different filter bank methods such as empirical mode decomposition, wavelet packet transform, and Fourier-based filtering. Secondly, a feature set is built using a proposed similarity measure termed cumulative spectral density index and used to estimate the mutual statistical dependence between each bandwidth-limited component and the raw signal. Finally, a classification scheme is carried out to distinguish the different types of faults. The methodology is tested in two laboratory experiments, including turbine blade degradation and rolling element bearing faults. The robustness of our approach is validated contaminating the signal with several levels of additive white Gaussian noise, obtaining high-performance outcomes that make the usage of vibration, acoustic, and vibroacoustic measurements in different applications comparable. As a result, the proposed fault detection based on filter bank similarity features is a promising methodology to implement in CM of rotating machinery, even using measurements with low signal-to-noise ratio.

Recovering Intrinsic Fragmental Vibrations Using the Generalized Subsystem Vibrational Analysis.

Science.gov (United States)

Tao, Yunwen; Tian, Chuan; Verma, Niraj; Zou, Wenli; Wang, Chao; Cremer, Dieter; Kraka, Elfi

2018-05-08

Normal vibrational modes are generally delocalized over the molecular system, which makes it difficult to assign certain vibrations to specific fragments or functional groups. We introduce a new approach, the Generalized Subsystem Vibrational Analysis (GSVA), to extract the intrinsic fragmental vibrations of any fragment/subsystem from the whole system via the evaluation of the corresponding effective Hessian matrix. The retention of the curvature information with regard to the potential energy surface for the effective Hessian matrix endows our approach with a concrete physical basis and enables the normal vibrational modes of different molecular systems to be legitimately comparable. Furthermore, the intrinsic fragmental vibrations act as a new link between the Konkoli-Cremer local vibrational modes and the normal vibrational modes.

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.

Analysis of two-phase flow induced vibrations in perpendiculary supported U-type piping systems

International Nuclear Information System (INIS)

Hiramatsu, Tsutomu; Komura, Yoshiaki; Ito, Atsushi.

1984-01-01

The perpose of this analysis is to predict the vibration level of a pipe conveying a two-phase flowing fluid. Experiments were carried out with a perpendiculary supported U-type piping system, conveying an air-water two-phase flow in a steady state condition. Fluctuation signals are observed by a void signal sensor, and power spectral densities and probability density functions are obtained from the void signals. Theoretical studies using FEM and an estimation of the exciting forces from the PSD of void signals, provided a good predictional estimation of vibration responses of the piping system. (author)

Multiple-Fault Detection Methodology Based on Vibration and Current Analysis Applied to Bearings in Induction Motors and Gearboxes on the Kinematic Chain

Directory of Open Access Journals (Sweden)

Juan Jose Saucedo-Dorantes

2016-01-01

Full Text Available Gearboxes and induction motors are important components in industrial applications and their monitoring condition is critical in the industrial sector so as to reduce costs and maintenance downtimes. There are several techniques associated with the fault diagnosis in rotating machinery; however, vibration and stator currents analysis are commonly used due to their proven reliability. Indeed, vibration and current analysis provide fault condition information by means of the fault-related spectral component identification. This work presents a methodology based on vibration and current analysis for the diagnosis of wear in a gearbox and the detection of bearing defect in an induction motor both linked to the same kinematic chain; besides, the location of the fault-related components for analysis is supported by the corresponding theoretical models. The theoretical models are based on calculation of characteristic gearbox and bearings fault frequencies, in order to locate the spectral components of the faults. In this work, the influence of vibrations over the system is observed by performing motor current signal analysis to detect the presence of faults. The obtained results show the feasibility of detecting multiple faults in a kinematic chain, making the proposed methodology suitable to be used in the application of industrial machinery diagnosis.

Spectral negentropy based sidebands and demodulation analysis for planet bearing fault diagnosis

Science.gov (United States)

Feng, Zhipeng; Ma, Haoqun; Zuo, Ming J.

2017-12-01

Planet bearing vibration signals are highly complex due to intricate kinematics (involving both revolution and spinning) and strong multiple modulations (including not only the fault induced amplitude modulation and frequency modulation, but also additional amplitude modulations due to load zone passing, time-varying vibration transfer path, and time-varying angle between the gear pair mesh lines of action and fault impact force vector), leading to difficulty in fault feature extraction. Rolling element bearing fault diagnosis essentially relies on detection of fault induced repetitive impulses carried by resonance vibration, but they are usually contaminated by noise and therefor are hard to be detected. This further adds complexity to planet bearing diagnostics. Spectral negentropy is able to reveal the frequency distribution of repetitive transients, thus providing an approach to identify the optimal frequency band of a filter for separating repetitive impulses. In this paper, we find the informative frequency band (including the center frequency and bandwidth) of bearing fault induced repetitive impulses using the spectral negentropy based infogram. In Fourier spectrum, we identify planet bearing faults according to sideband characteristics around the center frequency. For demodulation analysis, we filter out the sensitive component based on the informative frequency band revealed by the infogram. In amplitude demodulated spectrum (squared envelope spectrum) of the sensitive component, we diagnose planet bearing faults by matching the present peaks with the theoretical fault characteristic frequencies. We further decompose the sensitive component into mono-component intrinsic mode functions (IMFs) to estimate their instantaneous frequencies, and select a sensitive IMF with an instantaneous frequency fluctuating around the center frequency for frequency demodulation analysis. In the frequency demodulated spectrum (Fourier spectrum of instantaneous frequency) of

Investigation of active vibration drilling using acoustic emission and cutting size analysis

Directory of Open Access Journals (Sweden)

Yingjian Xiao

2018-04-01

Full Text Available This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit. A series of drill-off tests (DOTs were conducted where the drilling rate-of-penetration (ROP was measured at a series of step-wise increasing static bit thrusts or weight-on-bits (WOBs. Two active DOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples, and a passive DOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings. During drilling, an acoustic emission (AE system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis. The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor, a load cell, and an LVDT (linear variable differential transformer recorded the dynamic WOB and the ROP, respectively. Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB, facilitating comparison of the results at the same WOB. Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration, and the drill cuttings increased in size with a higher ROP. Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency. This indicated that larger fractures were being created to generate larger cutting size. Overall, these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which, at the same rotary speed, results in a higher ROP. Keywords: Active bit vibration, Diamond coring drilling, Drill

The experimental vibrational infrared spectrum of lemon peel and simulation of spectral properties of the plant cell wall

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Berezin, K. V.; Shagautdinova, I. T.; Chernavina, M. L.; Novoselova, A. V.; Dvoretskii, K. N.; Likhter, A. M.

2017-09-01

The experimental vibrational IR spectra of the outer part of lemon peel are recorded in the range of 3800-650 cm-1. The effect of artificial and natural dehydration of the peel on its vibrational spectrum is studied. It is shown that the colored outer layer of lemon peel does not have a noticeable effect on the vibrational spectrum. Upon 28-day storage of a lemon under natural laboratory conditions, only sequential dehydration processes are reflected in the vibrational spectrum of the peel. Within the framework of the theoretical DFT/B3LYP/6-31G(d) method, a model of a plant cell wall is developed consisting of a number of polymeric molecules of dietary fibers like cellulose, hemicellulose, pectin, lignin, some polyphenolic compounds (hesperetin glycoside-flavonoid), and a free water cluster. Using a supermolecular approach, the spectral properties of the wall of a lemon peel cell was simulated, and a detailed theoretical interpretation of the recorded vibrational spectrum is given.

Spectral analysis methods for vehicle interior vibro-acoustics identification

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Hosseini Fouladi, Mohammad; Nor, Mohd. Jailani Mohd.; Ariffin, Ahmad Kamal

2009-02-01

Noise has various effects on comfort, performance and health of human. Sound are analysed by human brain based on the frequencies and amplitudes. In a dynamic system, transmission of sound and vibrations depend on frequency and direction of the input motion and characteristics of the output. It is imperative that automotive manufacturers invest a lot of effort and money to improve and enhance the vibro-acoustics performance of their products. The enhancement effort may be very difficult and time-consuming if one relies only on 'trial and error' method without prior knowledge about the sources itself. Complex noise inside a vehicle cabin originated from various sources and travel through many pathways. First stage of sound quality refinement is to find the source. It is vital for automotive engineers to identify the dominant noise sources such as engine noise, exhaust noise and noise due to vibration transmission inside of vehicle. The purpose of this paper is to find the vibro-acoustical sources of noise in a passenger vehicle compartment. The implementation of spectral analysis method is much faster than the 'trial and error' methods in which, parts should be separated to measure the transfer functions. Also by using spectral analysis method, signals can be recorded in real operational conditions which conduce to more consistent results. A multi-channel analyser is utilised to measure and record the vibro-acoustical signals. Computational algorithms are also employed to identify contribution of various sources towards the measured interior signal. These achievements can be utilised to detect, control and optimise interior noise performance of road transport vehicles.

Preparation, crystal structure, vibrational spectral and density functional studies of bis (4-nitrophenol)-2,4,6-triamino-1,3,5-triazine monohydrate

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Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

2013-10-01

An organic-organic salt, bis (4-nitrophenol) 2,4,6-triamino 1,3,5-triazine monohydrate (BNPM) has been prepared by slow evaporation technique at room temperature. Single crystal X-ray diffraction analysis reveals that the compound crystallizes in triclinic system with centrosymmetric space group P-1. IR and Raman spectra of BNPM have been recorded and analyzed. The study has been extended to confocal Raman spectral analysis. Band assignments have been made for the melamine and p-nitrophenol molecules. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory calculations using Firefly (PC GAMESS) Version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with the experimental one. The Mulliken charges, HOMO-LUMO orbital energies are calculated and analyzed. The chemical structure of the compound was established by 1H NMR and 13C NMR spectra.

High throughput assessment of cells and tissues: Bayesian classification of spectral metrics from infrared vibrational spectroscopic imaging data.

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Bhargava, Rohit; Fernandez, Daniel C; Hewitt, Stephen M; Levin, Ira W

2006-07-01

Vibrational spectroscopy allows a visualization of tissue constituents based on intrinsic chemical composition and provides a potential route to obtaining diagnostic markers of diseases. Characterizations utilizing infrared vibrational spectroscopy, in particular, are conventionally low throughput in data acquisition, generally lacking in spatial resolution with the resulting data requiring intensive numerical computations to extract information. These factors impair the ability of infrared spectroscopic measurements to represent accurately the spatial heterogeneity in tissue, to incorporate robustly the diversity introduced by patient cohorts or preparative artifacts and to validate developed protocols in large population studies. In this manuscript, we demonstrate a combination of Fourier transform infrared (FTIR) spectroscopic imaging, tissue microarrays (TMAs) and fast numerical analysis as a paradigm for the rapid analysis, development and validation of high throughput spectroscopic characterization protocols. We provide an extended description of the data treatment algorithm and a discussion of various factors that may influence decision-making using this approach. Finally, a number of prostate tissue biopsies, arranged in an array modality, are employed to examine the efficacy of this approach in histologic recognition of epithelial cell polarization in patients displaying a variety of normal, malignant and hyperplastic conditions. An index of epithelial cell polarization, derived from a combined spectral and morphological analysis, is determined to be a potentially useful diagnostic marker.

DNA Methylation Changes in Valproic Acid-Treated HeLa Cells as Assessed by Image Analysis, Immunofluorescence and Vibrational Microspectroscopy.

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Giovana M B Veronezi

Full Text Available Valproic acid (VPA, a well-known histone deacetylase inhibitor, has been reported to affect the DNA methylation status in addition to inducing histone hyperacetylation in several cell types. In HeLa cells, VPA promotes histone acetylation and chromatin remodeling. However, DNA demethylation was not checked in this cell model for standing effects longer than those provided by histone acetylation, which is a rapid and transient phenomenon. Demonstration of VPA-induced DNA demethylation in HeLa cells would contribute to understanding the effect of VPA on an aggressive tumor cell line. In the present work, DNA demethylation in VPA-treated HeLa cells was assessed by image analysis of chromatin texture, the abundance of 5-methylcytosine (5mC immunofluorescence signals and Fourier transform-infrared (FT-IR microspectroscopy centered on spectral regions related to the vibration of-CH3 groups. Image analysis indicated that increased chromatin unpacking promoted by a 4-h-treatment with 1.0 mM VPA persisted for 24 h in the absence of the drug, suggesting the occurrence of DNA demethylation that was confirmed by decreased 5mC immunofluorescence signals. FT-IR spectra of DNA samples from 1 mM or 20 mM VPA-treated cells subjected to a peak fitting analysis of the spectral window for-CH3 stretching vibrations showed decreased vibrations and energy of these groups as a function of the decreased abundance of 5mC induced by increased VPA concentrations. Only the 20 mM-VPA treatment caused an increase in the ratio of -CH3 bending vibrations evaluated at 1375 cm-1 in relation to in-plane vibrations of overall cytosines evaluated at 1492 cm-1. CH3 stretching vibrations showed to be more sensitive than-CH3 bending vibrations, as detected with FT-IR microspectroscopy, for studies aiming to associate vibrational spectroscopy and changes in DNA 5mC abundance.

Measurements of ground motion and SSC dipole vibrations

International Nuclear Information System (INIS)

Parkhomchuk, V.V.; Shiltsev, V.D.; Weaver, H.J.

1993-06-01

The results of seismic ground measurements at the Superconducting Super Collider (SSC) site and investigations of vibrational properties of superconducting dipoles for the SSC are presented. Spectral analysis of the data obtained in the large frequency band from 0.05 Hz to 2000 Hz is done. Resonant behavior and the dipole-to-ground transform ratio are investigated. The influence of measured vibrations on SSC operations is considered

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

Absolute measurement of subnanometer scale vibration of cochlear partition of an excised guinea pig cochlea using spectral-domain phase-sensitive optical coherence tomography

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Subhash, Hrebesh M.; Choudhury, Niloy; Jacques, Steven L.; Wang, Ruikang K.; Chen, Fangyi; Zha, Dingjun; Nuttall, Alfred L.

2012-01-01

Direct measurement of absolute vibration parameters from different locations within the mammalian organ of Corti is crucial for understanding the hearing mechanics such as how sound propagates through the cochlea and how sound stimulates the vibration of various structures of the cochlea, namely, basilar membrane (BM), recticular lamina, outer hair cells and tectorial membrane (TM). In this study we demonstrate the feasibility a modified phase-sensitive spectral domain optical coherence tomography system to provide subnanometer scale vibration information from multiple angles within the imaging beam. The system has the potential to provide depth resolved absolute vibration measurement of tissue microstructures from each of the delay-encoded vibration images with a noise floor of ~0.3nm at 200Hz.

Estimation of spectral kurtosis

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Sutawanir

2017-03-01

Rolling bearings are the most important elements in rotating machinery. Bearing frequently fall out of service for various reasons: heavy loads, unsuitable lubrications, ineffective sealing. Bearing faults may cause a decrease in performance. Analysis of bearing vibration signals has attracted attention in the field of monitoring and fault diagnosis. Bearing vibration signals give rich information for early detection of bearing failures. Spectral kurtosis, SK, is a parameter in frequency domain indicating how the impulsiveness of a signal varies with frequency. Faults in rolling bearings give rise to a series of short impulse responses as the rolling elements strike faults, SK potentially useful for determining frequency bands dominated by bearing fault signals. SK can provide a measure of the distance of the analyzed bearings from a healthy one. SK provides additional information given by the power spectral density (psd). This paper aims to explore the estimation of spectral kurtosis using short time Fourier transform known as spectrogram. The estimation of SK is similar to the estimation of psd. The estimation falls in model-free estimation and plug-in estimator. Some numerical studies using simulations are discussed to support the methodology. Spectral kurtosis of some stationary signals are analytically obtained and used in simulation study. Kurtosis of time domain has been a popular tool for detecting non-normality. Spectral kurtosis is an extension of kurtosis in frequency domain. The relationship between time domain and frequency domain analysis is establish through power spectrum-autocovariance Fourier transform. Fourier transform is the main tool for estimation in frequency domain. The power spectral density is estimated through periodogram. In this paper, the short time Fourier transform of the spectral kurtosis is reviewed, a bearing fault (inner ring and outer ring) is simulated. The bearing response, power spectrum, and spectral kurtosis are plotted to

Vibration analysis and vibration damage assessment in nuclear and process equipment

International Nuclear Information System (INIS)

Pettigrew, M.J.; Taylor, C.E.; Fisher, N.J.; Yetisir, M.; Smith, B.A.W.

1997-01-01

Component failures due to excessive flow-induced vibration are still affecting the performance and reliability of process and nuclear components. The purpose of this paper is to discuss flow-induced vibration analysis and vibration damage prediction. Vibration excitation mechanisms are described with particular emphasis on fluid elastic instability. The dynamic characteristics of process and power equipment are explained. The statistical nature of some parameters, in particular support conditions, is discussed. The prediction of fretting-wear damage is approached from several points-of-view. An energy approach to formulate fretting-wear damage is proposed. (author)

VIBRATION ISOLATION SYSTEM PROBABILITY ANALYSIS

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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.

Experience in WWER fuel assemblies vibration analysis

International Nuclear Information System (INIS)

Ovtcharov, O.; Pavelko, V.; Usanov, A.; Arkadov, G.; Dolgov, A.; Molchanov, V.

2003-01-01

It is stated that the vibration studies of internals and the fuel assemblies should be conducted during the reactor designing, commissioning and commercial operation stages and the analysis methods being used should complement each other. The present paper describes the methods and main results of the vibration noise studies of internals and the fuel assemblies of the operating NPPs with WWER reactors, as an example of the implementation of the comprehensive approach to the analysis on equipment flow-induced vibration. At that, the characteristics of internals and fuel assemblies vibration loading were dealt jointly as they are elements of the same compound oscillating system and their vibrations have the interrelated nature

Application of the random vibration approach in the seismic analysis of LMFBR structures

International Nuclear Information System (INIS)

Preumont, A.

1988-01-01

The first part discusses the general topic of the spectral analysis of linear multi-degree-of-freedom structure subjected to a stationary random field. Particular attention is given to structures with non-classical damping and hereditary characteristics. The method is implemented in the computer programme RANDOM. Next, the same concepts are applied to multi-supported structures subjected to a stationary seismic excitation. The method is implemented in the computer programme SEISME. Two related problems are dealt with in the next two chapters: (i) the relation between the input of the random vibration analysis and the traditional ground motion specification for seismic analysis (the Design Response Spectra) and (ii) the application of random vibration techniques to the direct generation of floor response spectra. Finally the problem of extracting information from costly time history analyses is addressed. This study has mainly been concerned with the methodology and the development of appropriate softwares. Some qualitative conclusions have been drawn regarding the expected benefit of the approach. They have been judged promising enough to motivate a benchmark exercise. Specifically, the random vibration approach will be compared to the current approximate methods (response spectrum) and time-history analyses (considered as representative of the true response) for a set of typical structures. The hope is that some of the flaws of the current approximate methods can be removed

[Infrared spectral analysis for calcined borax].

Science.gov (United States)

Zhao, Cui; Ren, Li-Li; Wang, Dong; Zhou, Ping; Zhang, Qian; Wang, Bo-Tao

2011-08-01

To valuate the quality of calcined borax which is sold in the market, 18 samples of calcined borax were studied using the Fourier transform infrared, and samples with different water content were selected and analyzed. Then, the results of analysis were used to evaluate the quality of calcined borax. Results show that the infrared spectra of calcined borax include OH vibration, BO3(-3) vibration and BO4(5-) vibration absorption bands. The position and width of OH vibration absorption band depend on the level of water content, and the more the water content, the wider the absorption band. The number of BO3(3-) vibration and BO4(5-) vibration bands also depend on the level of water content, and the more the water content, and the stronger the hydrogen bond and the lower the symmetry of B atoms, the more the number of infrared absorption peaks. It was concluded that because the quality of calcined borax has direct correlation with water content, the infrared spectroscopy is an express and objective approach to quality analysis and evaluation of calcined borax.

Intrinsic chirality and prochirality at Air/R-(+)- and S-(-)-limonene interfaces: spectral signatures with interference chiral sum-frequency generation vibrational spectroscopy.

Science.gov (United States)

Fu, Li; Zhang, Yun; Wei, Zhe-Hao; Wang, Hong-Fei

2014-09-01

We report in this work detailed measurements of the chiral and achiral sum-frequency vibrational spectra in the C-H stretching vibration region (2800-3050 cm(-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 RS racemic mixture (50/50 equal amount mixture), show that the corresponding molecular groups of the R and S enantiomers are with the same interfacial orientations. The interference chiral SFG spectra of the limonene enantiomers exhibit a spectral signature from the chiral response of the Cα-H stretching mode, and a spectral signature from the prochiral response of the CH(2) asymmetric stretching mode, respectively. The chiral spectral feature of the Cα-H stretching mode changes sign from R-(+)-limonene to S-(-)-limonene surfaces, and disappears for the RS racemic mixture surface. While the prochiral spectral feature of the CH(2) asymmetric stretching mode is the same for R-(+)-limonene and S-(-)-limonene surfaces, and also surprisingly remains the same for the RS racemic mixture surface. Therefore, the structures of the R-(+)-limonene and the S-(-)-limonene at the liquid interfaces are nevertheless not mirror images to each other, even though the corresponding groups have the same tilt angle from the interfacial normal, i.e., the R-(+)-limonene and the S-(-)-limonene at the surface are diastereomeric instead of enantiomeric. These results provide detailed information in understanding the structure and chirality of molecular interfaces and demonstrate the sensitivity and potential of SFG-VS as a unique spectroscopic tool for chirality characterization and chiral recognition at the molecular interface. © 2014 Wiley Periodicals, Inc.

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.

Multivariat least-squares methods applied to the quantitative spectral analysis of multicomponent samples

International Nuclear Information System (INIS)

Haaland, D.M.; Easterling, R.G.; Vopicka, D.A.

1985-01-01

In an extension of earlier work, weighted multivariate least-squares methods of quantitative FT-IR analysis have been developed. A linear least-squares approximation to nonlinearities in the Beer-Lambert law is made by allowing the reference spectra to be a set of known mixtures, The incorporation of nonzero intercepts in the relation between absorbance and concentration further improves the approximation of nonlinearities while simultaneously accounting for nonzero spectra baselines. Pathlength variations are also accommodated in the analysis, and under certain conditions, unknown sample pathlengths can be determined. All spectral data are used to improve the precision and accuracy of the estimated concentrations. During the calibration phase of the analysis, pure component spectra are estimated from the standard mixture spectra. These can be compared with the measured pure component spectra to determine which vibrations experience nonlinear behavior. In the predictive phase of the analysis, the calculated spectra are used in our previous least-squares analysis to estimate sample component concentrations. These methods were applied to the analysis of the IR spectra of binary mixtures of esters. Even with severely overlapping spectral bands and nonlinearities in the Beer-Lambert law, the average relative error in the estimated concentration was <1%

[Structure analysis of disease-related proteins using vibrational spectroscopy].

Science.gov (United States)

Hiramatsu, Hirotsugu

2014-01-01

Analyses of the structure and properties of identified pathogenic proteins are important for elucidating the molecular basis of diseases and in drug discovery research. Vibrational spectroscopy has advantages over other techniques in terms of sensitivity of detection of structural changes. Spectral analysis, however, is complicated because the spectrum involves a substantial amount of information. This article includes examples of structural analysis of disease-related proteins using vibrational spectroscopy in combination with additional techniques that facilitate data acquisition and analysis. Residue-specific conformation analysis of an amyloid fibril was conducted using IR absorption spectroscopy in combination with (13)C-isotope labeling, linear dichroism measurement, and analysis of amide I band features. We reveal a pH-dependent property of the interacting segment of an amyloidogenic protein, β2-microglobulin, which causes dialysis-related amyloidosis. We also reveal the molecular mechanisms underlying pH-dependent sugar-binding activity of human galectin-1, which is involved in cell adhesion, using spectroscopic techniques including UV resonance Raman spectroscopy. The decreased activity at acidic pH was attributed to a conformational change in the sugar-binding pocket caused by protonation of His52 (pKa 6.3) and the cation-π interaction between Trp68 and the protonated His44 (pKa 5.7). In addition, we show that the peak positions of the Raman bands of the C4=C5 stretching mode at approximately 1600 cm(-1) and the Nπ-C2-Nτ bending mode at approximately 1405 cm(-1) serve as markers of the His side-chain structure. The Raman signal was enhanced 12 fold using a vertical flow apparatus.

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.)

Underground measurements of seismic vibrations at the SSC site

International Nuclear Information System (INIS)

Shiltsev, V.D.; Parkhomchuk, V.V.; Weaver, H.J.

1995-01-01

The results of underground measurements of seismic vibrations at the tunnel depth of the Superconducting Super Collider (SSC) site are presented. Spectral analysis of the data obtained in the frequency band from 0.05 Hz to 1500 Hz is performed. It is found that amplitudes of ambient ground motion are less than requirements for the Collider, but cultural vibrations are unacceptably large and will cause fast growth of transverse emittance of the SSC beams

Thermal infrared spectral analysis of compacted fine-grained mineral mixtures: implications for spectral interpretation of lithified sedimentary materials on Mars

Science.gov (United States)

Pan, C.; Rogers, D.

2012-12-01

Characterizing the thermal infrared (TIR) spectral mixing behavior of compacted fine-grained mineral assemblages is necessary for facilitating quantitative mineralogy of sedimentary surfaces from spectral measurements. Previous researchers have demonstrated that TIR spectra from igneous and metamorphic rocks as well as coarse-grained (>63 micron) sand mixtures combine in proportion to their volume abundance. However, the spectral mixing behavior of compacted, fine-grained mineral mixtures that would be characteristic of sedimentary depositional environments has received little attention. Here we characterize the spectral properties of pressed pellet samples of pestle and centrifuged to obtain less than 10 micron size. Pure phases and mixtures of two, three and four components were made in varying proportions by volume. All of the samples were pressed into pellets at 15000PSI to minimize volume scattering. Thermal infrared spectra of pellets were measured in the Vibrational Spectroscopy Laboratory at Stony Brook University with a Thermo Fisher Nicolet 6700 Fourier transform infrared Michelson interferometer from ~225 to 2000 cm-1. Our preliminary results indicate that some pelletized samples have contributions from volume scattering, which leads to non-linear spectral combinations. It is not clear if the transparency features (which arise from multiple surface reflections of incident photons) are due to minor clinging fines on an otherwise specular pellet surface or to partially transmitted energy through optically thin grains in the compacted mixture. Inclusion of loose powder (analysis of TES and Mini-TES data of lithified sedimentary deposits.

Examination of Spectral Transformations on Spectral Mixture Analysis

Science.gov (United States)

Deng, Y.; Wu, C.

2018-04-01

While many spectral transformation techniques have been applied on spectral mixture analysis (SMA), few study examined their necessity and applicability. This paper focused on exploring the difference between spectrally transformed schemes and untransformed scheme to find out which transformed scheme performed better in SMA. In particular, nine spectrally transformed schemes as well as untransformed scheme were examined in two study areas. Each transformed scheme was tested 100 times using different endmember classes' spectra under the endmember model of vegetation- high albedo impervious surface area-low albedo impervious surface area-soil (V-ISAh-ISAl-S). Performance of each scheme was assessed based on mean absolute error (MAE). Statistical analysis technique, Paired-Samples T test, was applied to test the significance of mean MAEs' difference between transformed and untransformed schemes. Results demonstrated that only NSMA could exceed the untransformed scheme in all study areas. Some transformed schemes showed unstable performance since they outperformed the untransformed scheme in one area but weakened the SMA result in another region.

Spectral methods for study of the G-protein-coupled receptor rhodopsin: I. Vibrational and electronic spectroscopy

Science.gov (United States)

Struts, A. V.; Barmasov, A. V.; Brown, M. F.

2015-05-01

Here we review the application of modern spectral methods for the study of G-protein-coupled receptors (GPCRs) using rhodopsin as a prototype. Because X-ray analysis gives us immobile snapshots of protein conformations, it is imperative to apply spectroscopic methods for elucidating their function: vibrational (Raman, FTIR), electronic (UV-visible absorption, fluorescence) spectroscopies, and magnetic resonance (electron paramagnetic resonance, EPR), and nuclear magnetic resonance (NMR). In the first of the two companion articles, we discuss the application of optical spectroscopy for studying rhodopsin in a membrane environment. Information is obtained regarding the time-ordered sequence of events in rhodopsin activation. Isomerization of the chromophore and deprotonation of the retinal Schiff base leads to a structural change of the protein involving the motion of helices H5 and H6 in a pH-dependent process. Information is obtained that is unavailable from X-ray crystallography, which can be combined with spectroscopic studies to achieve a more complete understanding of GPCR function.

The validation of an aerospace structure through the sine vibration analysis

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Cristina-Diana BRATU

2018-06-01

Full Text Available Sinusoidal vibrations represent an ideal case. Technically, it is quite hard to generate pure sinusoidal vibrations without containing other spectral components, called harmonics. Sinusoidal vibrations can appear on propeller, propulsion and turbofan aircraft as well as on helicopters and aerospace structures. They can occur during different phases of flight (take-off, ascent, cruise, landing, etc.. The aim of this article is to present how a structure can be validated by using the mathematical formulas or a FEM software such as PATRAN-NASTRAN (and the equations behind it. As an application, an aerospace structure such as thruster brackets will be analyzed. A sinusoidal signal of 1g was applied on the attachment points and the response was read from the center of gravity of the thrusters.

Determining the static electronic and vibrational energy correlations via two-dimensional electronic-vibrational spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Dong, Hui; Lewis, Nicholas H. C.; Oliver, Thomas A. A.; Fleming, Graham R., E-mail: grfleming@lbl.gov [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, Californial 94720 (United States); Kavli Energy NanoSciences Institute at Berkeley, Berkeley, California 94720 (United States)

2015-05-07

Changes in the electronic structure of pigments in protein environments and of polar molecules in solution inevitably induce a re-adaption of molecular nuclear structure. Both changes of electronic and vibrational energies can be probed with visible or infrared lasers, such as two-dimensional electronic spectroscopy or vibrational spectroscopy. The extent to which the two changes are correlated remains elusive. The recent demonstration of two-dimensional electronic-vibrational (2DEV) spectroscopy potentially enables a direct measurement of this correlation experimentally. However, it has hitherto been unclear how to characterize the correlation from the spectra. In this paper, we present a theoretical formalism to demonstrate the slope of the nodal line between the excited state absorption and ground state bleach peaks in the spectra as a characterization of the correlation between electronic and vibrational transition energies. We also show the dynamics of the nodal line slope is correlated to the vibrational spectral dynamics. Additionally, we demonstrate the fundamental 2DEV spectral line-shape of a monomer with newly developed response functions.

Proposal to use vibration analysis steering components and car body to monitor, for example, the state of unbalance wheel

Science.gov (United States)

Janczur, R.

2016-09-01

The results of road tests of car VW Passat equipped with tires of size 195/65 R15, on the influence of the unbalancing front wheel on vibration of the parts of steering system, steering wheel and the body of the vehicle have been presented in this paper. Unbalances wheels made using weights of different masses, placed close to the outer edge of the steel rim and checked on the machine Hunter GSP 9700 for balancing wheels. The recorded waveforms vibration steering components and car body, at different constant driving speeds, subjected to spectral analysis to determine the possibility of isolating vibration caused by unbalanced wheel in various states and coming from good quality asphalt road surface. The results were discussed in terms of the possibility of identifying the state of unbalancing wheels and possible changes in radial stiffness of the tire vibration transmitted through the system driving wheel on the steering wheel. Vibration analysis steering components and car body, also in the longitudinal direction, including information from the CAN bus of the state of motion of the car, can be used to monitor the development of the state of unbalance wheel, tire damage or errors shape of brake discs or brake drums, causing pulsations braking forces.

Study on the status of the working bodies grinding machines based on vibration analysis

Directory of Open Access Journals (Sweden)

S. T. Antipov

2016-01-01

Full Text Available Improvement of technology and engineering aimed at the use of secondary raw material is an important task. One of the most important operations in the preparation of raw materials for mixed feeds is fine grinding. In this regard, the article discusses the grinding equipment allowing to obtain raw materials of higher quality with the lower energy consumption. Methods and diagnostic tools were proposed, the principle of determining the locations (points of installation of vibration measurement sensors as well as the choice of the vibration signal analysis method were considered. Investigation of the state of the disintegrator working bodies was carried out in the workshop of LLC PСF "Luch 2000". The object of study is a disintegrator with rotors diameter of 350 mm, each of them having two rows of pins. The result of the experiment revealed that during the operation the working bodies of grinding machines are exposed to uneven wear and under the action of multicycle load micro-cracks and fatigue fractures occur. The method of spectral analysis revealed the appearance of harmonics with large vibration at a frequency of 126 Hz, as well as multiple frequencies, allowing a high degre e of probability to determine not only the actual state of the working bodies, but also to predict the defect development trend. Based on the analysis of the spectra, the decision on further time operation of the equipment is made, which significantly reduces the probability of an emergency stop of equipment and expensive repairs. The research data will be relevant when using vibration diagnostics tools in enterprises, as well as in the design, construction and choice of materials for grinding equipment.

Application of comparative vibrational spectroscopic and mechanistic studies in analysis of fisetin structure

Science.gov (United States)

Dimitrić Marković, Jasmina M.; Marković, Zoran S.; Milenković, Dejan; Jeremić, Svetlana

2011-12-01

This paper addresses experimental and theoretical research in fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) structure by means of experimental IR and Raman spectroscopies and mechanistic calculations. Density Functional Theory calculations, with M05-2X functional and the 6-311+G (2df, p) basis set implemented in the Gaussian 09 package, are performed with the aim to support molecular structure, vibrational bands' positions and their intensities. Potential energy distribution (PED) values and the description of the largest vibrational contributions to the normal modes are calculated. The most intense bands appear in the 1650-1500 cm -1 wavenumber region. This region involves a combination of the C dbnd O, C2 dbnd C3 and C-C stretching vibrational modes. Most of the bands in the 1500-1000 cm -1 range involve C-C stretching, O-C stretching and in-plane C-C-H, C-O-H, C-C-O and C-C-C bending vibrations of the rings. The region below 1000 cm -1 is characteristic to the combination of in plane C-C-C-H, H-C-C-H, C-C-C-C, C-C-O-C and out of plane O-C-C-C, C-C-O-C, C-C-C-C torsional modes. The Raman spectra of baicalein and quercetin were used for qualitative comparison with fisetin spectrum and verification of band assignments. The applied detailed vibrational spectral analysis and the assignments of the bands, proposed on the basis of fundamentals, reproduced the experimental results with high degree of accuracy.

Flow-induced vibration analysis of a helical coil steam generator experiment using large eddy simulation

Energy Technology Data Exchange (ETDEWEB)

Yuan, Haomin; Solberg, Jerome; Merzari, Elia; Kraus, Adam; Grindeanu, Iulian

2017-10-01

This paper describes a numerical study of flow-induced vibration in a helical coil steam generator experiment conducted at Argonne National Laboratory in the 1980s. In the experiment, a half-scale sector model of a steam generator helical coil tube bank was subjected to still and flowing air and water, and the vibrational characteristics were recorded. The research detailed in this document utilizes the multi-physics simulation toolkit SHARP developed at Argonne National Laboratory, in cooperation with Lawrence Livermore National Laboratory, to simulate the experiment. SHARP uses the spectral element code Nek5000 for fluid dynamics analysis and the finite element code DIABLO for structural analysis. The flow around the coil tubes is modeled in Nek5000 by using a large eddy simulation turbulence model. Transient pressure data on the tube surfaces is sampled and transferred to DIABLO for the structural simulation. The structural response is simulated in DIABLO via an implicit time-marching algorithm and a combination of continuum elements and structural shells. Tube vibration data (acceleration and frequency) are sampled and compared with the experimental data. Currently, only one-way coupling is used, which means that pressure loads from the fluid simulation are transferred to the structural simulation but the resulting structural displacements are not fed back to the fluid simulation

Vibration analysis in nuclear power plant using neural networks

International Nuclear Information System (INIS)

Loskiewicz-Buczak, A.; Alguindigue, I.E.

1993-01-01

Vibration monitoring of components in nuclear power plants has been used for a number of years. This technique involves the analysis of vibration data coming from vital components of the plant to detect features which reflect the operational state of machinery. The analysis leads to the identification of potential failures and their causes, and makes it possible to perform efficient preventive maintenance. This paper documents the authors' work on the design of a vibration monitoring methodology enhanced by neural network technology. This technology provides an attractive complement to traditional vibration analysis because of the potential of neural networks to handle data which may be distorted or noisy. This paper describes three neural networks-based methods for the automation of some of the activities related to motion and vibration monitoring in engineering systems

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.

Wavelet-based spectral finite element dynamic analysis for an axially moving Timoshenko beam

Science.gov (United States)

Mokhtari, Ali; Mirdamadi, Hamid Reza; Ghayour, Mostafa

2017-08-01

In this article, wavelet-based spectral finite element (WSFE) model is formulated for time domain and wave domain dynamic analysis of an axially moving Timoshenko beam subjected to axial pretension. The formulation is similar to conventional FFT-based spectral finite element (SFE) model except that Daubechies wavelet basis functions are used for temporal discretization of the governing partial differential equations into a set of ordinary differential equations. The localized nature of Daubechies wavelet basis functions helps to rule out problems of SFE model due to periodicity assumption, especially during inverse Fourier transformation and back to time domain. The high accuracy of WSFE model is then evaluated by comparing its results with those of conventional finite element and SFE results. The effects of moving beam speed and axial tensile force on vibration and wave characteristics, and static and dynamic stabilities of moving beam are investigated.

Noise and vibration analysis system

International Nuclear Information System (INIS)

Johnsen, J.R.; Williams, R.L.

1985-01-01

The analysis of noise and vibration data from an operating nuclear plant can provide valuable information that can identify and characterize abnormal conditions. Existing plant monitoring equipment, such as loose parts monitoring systems (LPMS) and neutron flux detectors, may be capable of gathering noise data, but may lack the analytical capability to extract useful meanings hidden in the noise. By analyzing neutron noise signals, the structural motion and integrity of core components can be assessed. Computer analysis makes trending of frequency spectra within a fuel cycle and from one cycle to another a practical means of core internals monitoring. The Babcock and Wilcox Noise and Vibration Analysis System (NVAS) is a powerful, compact system that can automatically perform complex data analysis. The system can acquire, process, and store data, then produce report-quality plots of the important parameter. Software to perform neutron noise analysis and loose parts analysis operates on the same hardware package. Since the system is compact, inexpensive, and easy to operate, it allows utilities to perform more frequency analyses without incurring high costs and provides immediate results

Vibration Analysis of Beam and Block Precast Slab System due to Human Vibrations

Science.gov (United States)

Chik, T. N. T.; Kamil, M. R. H.; Yusoff, N. A.

2018-04-01

Beam and block precast slabs system are very efficient which generally give maximum structural performance where their voids based on the design of the unit soffit block allow a significant reduction of the whole slab self-weight. Initially for some combinations of components or the joint connection of the structural slab, this structural system may be susceptible to excessive vibrations that could effects the performance and also serviceability. Dynamic forces are excited from people walking and jumping which produced vibrations to the slab system in the buildings. Few studies concluded that human induced vibration on precast slabs system may be harmful to structural performance and mitigate the human comfort level. This study will investigate the vibration analysis of beam and block precast slab by using finite element method at the school building. Human activities which are excited from jumping and walking will induce the vibrations signal to the building. Laser Doppler Vibrometer (LDV) was used to measure the dynamic responses of slab towards the vibration sources. Five different points were assigned specifically where each of location will determine the behaviour of the entire slabs. The finite element analyses were developed in ABAQUS software and the data was further processed in MATLAB ModalV to assess the vibration criteria. The results indicated that the beam and block precast systems adequate enough to the vibration serviceability and human comfort criteria. The overall vibration level obtained was fell under VC-E curve which it is generally under the maximum permissible level of vibrations. The vibration level on the slab is acceptable within the limit that have been used by Gordon.

Application of comparative vibrational spectroscopic and mechanistic studies in analysis of fisetin structure.

Science.gov (United States)

Dimitrić Marković, Jasmina M; Marković, Zoran S; Milenković, Dejan; Jeremić, Svetlana

2011-12-01

This paper addresses experimental and theoretical research in fisetin (2-(3,4-dihydroxyphenyl)-3,7-dihydroxychromen-4-one) structure by means of experimental IR and Raman spectroscopies and mechanistic calculations. Density Functional Theory calculations, with M05-2X functional and the 6-311+G (2df, p) basis set implemented in the Gaussian 09 package, are performed with the aim to support molecular structure, vibrational bands' positions and their intensities. Potential energy distribution (PED) values and the description of the largest vibrational contributions to the normal modes are calculated. The most intense bands appear in the 1650-1500 cm(-1) wavenumber region. This region involves a combination of the CO, C2C3 and C-C stretching vibrational modes. Most of the bands in the 1500-1000 cm(-1) range involve C-C stretching, O-C stretching and in-plane C-C-H, C-O-H, C-C-O and C-C-C bending vibrations of the rings. The region below 1000 cm(-1) is characteristic to the combination of in plane C-C-C-H, H-C-C-H, C-C-C-C, C-C-O-C and out of plane O-C-C-C, C-C-O-C, C-C-C-C torsional modes. The Raman spectra of baicalein and quercetin were used for qualitative comparison with fisetin spectrum and verification of band assignments. The applied detailed vibrational spectral analysis and the assignments of the bands, proposed on the basis of fundamentals, reproduced the experimental results with high degree of accuracy. Copyright © 2011 Elsevier B.V. All rights reserved.

SPECTRAL ANALYSIS OF EXCHANGE RATES

Directory of Open Access Journals (Sweden)

ALEŠA LOTRIČ DOLINAR

2013-06-01

Full Text Available Using spectral analysis is very common in technical areas but rather unusual in economics and finance, where ARIMA and GARCH modeling are much more in use. To show that spectral analysis can be useful in determining hidden periodic components for high-frequency finance data as well, we use the example of foreign exchange rates

Development of vibrational analysis for detection of antisymmetric shells

International Nuclear Information System (INIS)

Esmailzadeh Khadem, S.; Mahmoodi, M.; Rezaee, M.

2002-01-01

In this paper, vibrational behavior of bodies of revolution with different types of structural faults is studied. Since vibrational characteristics of structures are natural properties of system, the existence of any structural faults causes measurable changes in these properties. Here, this matter is demonstrated. In other words, vibrational behavior of a body of revolution with no structural faults is analyzed by two methods of I) numerical analysis using super sap software, II) Experimental model analysis, and natural frequencies and mode shapes are obtained. Then, different types of cracks are introduced in the structure, and analysis is repeated and the results are compared. Based on this study, one may perform crack detection by measuring the natural frequencies and mode shapes of the samples and comparing with reference information obtained from the vibration analysis of the original structure with no fault

Analysis of solid-state transformations of pharmaceutical compounds using vibrational spectroscopy

DEFF Research Database (Denmark)

Heinz, Andrea; Strachan, Clare J; Gordon, Keith C

2009-01-01

OBJECTIVES: Solid-state transformations may occur during any stage of pharmaceutical processing and upon storage of a solid dosage form. Early detection and quantification of these transformations during the manufacture of solid dosage forms is important since the physical form of an active...... pharmaceutical ingredient can significantly influence its processing behaviour, including powder flow and compressibility, and biopharmaceutical properties such as solubility, dissolution rate and bioavailability. KEY FINDINGS: Vibrational spectroscopic techniques such as infrared, near-infrared, Raman and, most...... multivariate approaches where even overlapping spectral bands can be analysed. SUMMARY: This review discusses the applications of different vibrational spectroscopic techniques to detect and monitor solid-state transformations possible for crystalline polymorphs, hydrates and amorphous forms of pharmaceutical...

Vibrational spectral investigation on xanthine and its derivatives—theophylline, caffeine and theobromine

Science.gov (United States)

Gunasekaran, S.; Sankari, G.; Ponnusamy, S.

2005-01-01

A normal coordinate analysis has been carried out on four compounds having a similar ring structure with different side chain substitutions, which are xanthine, caffeine, theophylline, and theobromine. Xanthine is chemically known as 2,6-dihydroxy purine. Caffeine, theophylline and theobromine are methylated xanthines. Considering the methyl groups as point mass, the number of normal modes of vibrations can be distributed as Γ vib=27 A'+12 A″ based on C s point group symmetry associated with the structures. In the present work 15 A' and 12 A″ normal modes are considered. A new set of orthonormal symmetry co-ordinates have been constructed. Wilson's F- G matrix method has been adopted for the normal coordinate analysis. A satisfactory vibrational band assignment has been made by employing the FTIR and FT Raman spectra of the compounds. The potential energy distribution is calculated with the arrived values of the force constants and hence the agreement of the frequency assignment has been checked.

Vibrational spectral investigation on xanthine and its derivatives--theophylline, caffeine and theobromine.

Science.gov (United States)

Gunasekaran, S; Sankari, G; Ponnusamy, S

2005-01-01

A normal coordinate analysis has been carried out on four compounds having a similar ring structure with different side chain substitutions, which are xanthine, caffeine, theophylline, and theobromine. Xanthine is chemically known as 2,6-dihydroxy purine. Caffeine, theophylline and theobromine are methylated xanthines. Considering the methyl groups as point mass, the number of normal modes of vibrations can be distributed as Gamma(vib) = 27 A' + 12 A" based on C(s) point group symmetry associated with the structures. In the present work 15 A' and 12 A'' normal modes are considered. A new set of orthonormal symmetry co-ordinates have been constructed. Wilson's F-G matrix method has been adopted for the normal coordinate analysis. A satisfactory vibrational band assignment has been made by employing the FTIR and FT Raman spectra of the compounds. The potential energy distribution is calculated with the arrived values of the force constants and hence the agreement of the frequency assignment has been checked.

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.

Construction of a Vibration Monitoring System for HANARO's Rotating Machinery and Analysis of Pump Vibration Signals

International Nuclear Information System (INIS)

Ryu, Jeong Soo; Yoon, Doo Byung

2005-01-01

HANARO is an open-tank-in-pool type research reactor with a thermal power of 30MW. In order to remove the heat generated by the reactor core and the reflector vessel, primary cooling pumps and reflector cooling pumps circulate coolant. These pumps are installed at the RCI(Reactor Concrete Island) which is covered by heavy concrete hatches. For the prevention of an abnormal operation of these pumps in the RCI, it is necessary to construct a vibration monitoring system that provides an alarm signal to the reactor control room when the rotating speed or the vibration level exceeds the allowable limit. The first objective of this work is to construct a vibration monitoring system for HANARO's rotating machinery. The second objective is to verify the possibility of condition monitoring of the rotating machinery. To construct a vibration monitoring system, as a first step, the standards and references related to the vibration monitoring system were investigated. In addition, to determine the number and the location of sensors that can effectively characterize the overall vibration of a pump, the vibration of the primary cooling pumps and the reflector cooling pumps were measured. Based on these results, detailed construction plans for the vibration monitoring system for HANARO were established. Then, in accordance with the construction plans, the vibration monitoring system for HANARO's rotating machinery was manufactured and installed at HANARO. To achieve the second objective, FFT analysis and bearing fault detection of the measured vibration signals were performed. The analysis results demonstrate that the accelerometers mounted at the bearing locations of the pumps can effectively monitor the pump condition

Spectral studies of new fullerene-tetrathiafulvalene based system

International Nuclear Information System (INIS)

Laskowska, Barbara; Lapinski, Andrzej; Graja, Andrzej; Hudhomme, Pietrick

2007-01-01

Molecular and electronic structures as well as electronic and vibrational spectra of compounds 1-3 were investigated. The spectra were recorded in the large spectral range from 400 to 50,000 cm -1 ; our interest was focused on the electronic excitations of both moieties of the dyad and the intramolecular vibrations of the dyad's components. With the help of the Gaussian 03 program, molecular geometry, electron structure and normal mode analysis for the dyad and/or reference compounds were studied. An assignment of the main vibrational bands of the dyad and its reference molecules was made taking into consideration their IR and Raman spectra as well as results of the normal mode analysis. In principle, the intramolecular vibrations typical for C 60 and tetrathiafulvalene (TTF) derivatives can be found in the spectra of the dyad; the bands' frequencies are insignificantly shifted comparing with the separated molecules but their shape is usually modified. It suggests that symmetry and molecular structure of both components of the dyad are rather kept after dyad's formation but redistribution of charges occurs

Vibrational emission analysis of the CN molecules in laser-induced breakdown spectroscopy of organic compounds

Energy Technology Data Exchange (ETDEWEB)

Fernández-Bravo, Ángel; Delgado, Tomás; Lucena, Patricia; Laserna, J. Javier, E-mail: laserna@uma.es

2013-11-01

Laser-induced breakdown spectroscopy (LIBS) of organic materials is based on the analysis of atomic and ionic emission lines and on a few molecular bands, the most important being the CN violet system and the C{sub 2} Swan system. This paper is focused in molecular emission of LIBS plasmas based on the CN (B{sup 2}Σ–X{sup 2}Σ) band, one of the strongest emissions appearing in all carbon materials when analyzed in air atmosphere. An analysis of this band with sufficient spectral resolution provides a great deal of information on the molecule, which has revealed that valuable information can be obtained from the plume chemistry and dynamics affecting the excitation mechanisms of the molecules. The vibrational emission of this molecular band has been investigated to establish the dependence of this emission on the molecular structure of the materials. The paper shows that excitation/emission phenomena of molecular species observed in the plume depend strongly on the time interval selected and on the irradiance deposited on the sample surface. Precise time resolved LIBS measurements are needed for the observation of distinctive CN emission. For the organic compounds studied, larger differences in the behavior of the vibrational emission occur at early stages after plasma ignition. Since molecular emission is generally more complex than that involving atomic emission, local plasma conditions as well as plume chemistry may induce changes in vibrational emission of molecules. As a consequence, alterations in the distribution of the emissions occur in terms of relative intensities, being sensitive to the molecular structure of every single material. - Highlights: • Vibrational emission of CN species in laser-induced plasmas has been investigated. • Distribution of vibrational emission of CN has been found to be time dependent. • Laser irradiance affects the vibrational distribution of the CN molecules. • Plume chemistry controls the excitation mechanisms of CN

SPAM- SPECTRAL ANALYSIS MANAGER (UNIX VERSION)

Science.gov (United States)

Solomon, J. E.

1994-01-01

The Spectral Analysis Manager (SPAM) was developed to allow easy qualitative analysis of multi-dimensional imaging spectrometer data. Imaging spectrometers provide sufficient spectral sampling to define unique spectral signatures on a per pixel basis. Thus direct material identification becomes possible for geologic studies. SPAM provides a variety of capabilities for carrying out interactive analysis of the massive and complex datasets associated with multispectral remote sensing observations. In addition to normal image processing functions, SPAM provides multiple levels of on-line help, a flexible command interpretation, graceful error recovery, and a program structure which can be implemented in a variety of environments. SPAM was designed to be visually oriented and user friendly with the liberal employment of graphics for rapid and efficient exploratory analysis of imaging spectrometry data. SPAM provides functions to enable arithmetic manipulations of the data, such as normalization, linear mixing, band ratio discrimination, and low-pass filtering. SPAM can be used to examine the spectra of an individual pixel or the average spectra over a number of pixels. SPAM also supports image segmentation, fast spectral signature matching, spectral library usage, mixture analysis, and feature extraction. High speed spectral signature matching is performed by using a binary spectral encoding algorithm to separate and identify mineral components present in the scene. The same binary encoding allows automatic spectral clustering. Spectral data may be entered from a digitizing tablet, stored in a user library, compared to the master library containing mineral standards, and then displayed as a timesequence spectral movie. The output plots, histograms, and stretched histograms produced by SPAM can be sent to a lineprinter, stored as separate RGB disk files, or sent to a Quick Color Recorder. SPAM is written in C for interactive execution and is available for two different

A Study on the Vibration Measurement and Analysis of Rotating Machine Foundations

Energy Technology Data Exchange (ETDEWEB)

Lee, Jong Rim; Jeon, Kyu Sik; Suh, Young Pyo; Cho, Chul Hwan; Kim, Sung Taeg; Lee, Myung Kyu [Korea Electric Power Research Institute, Taejon (Korea, Republic of)

1996-12-31

To search for the cause of vibration problem of rotating machine in the power plant, first the rotating machine is classified according to their type and each vibration characteristic is reviewed. The criteria for the evaluation of mechanical vibration effect on the structure and human being during the design of machine foundation is described below. The foundation of rotating machine is classified according to its shape and some factors are described which should be considered during dynamic modeling analysis for its correct result. Also the methods of incorporating foundation vibration into mechanical vibration analysis are reviewed. Type of vibration measurement and analysis which is used to find out the dynamic characteristic of structure is described in accordance with its signal processing and measuring method. Measurement of vibration and its analysis when there occurs real vibration troubles in power plant are compared with the results of numerical modeling as case studies. (author). 16 refs., 23 figs.

Energy Finite Element Analysis Developments for Vibration Analysis of Composite Aircraft Structures

Science.gov (United States)

Vlahopoulos, Nickolas; Schiller, Noah H.

2011-01-01

The Energy Finite Element Analysis (EFEA) has been utilized successfully for modeling complex structural-acoustic systems with isotropic structural material properties. In this paper, a formulation for modeling structures made out of composite materials is presented. An approach based on spectral finite element analysis is utilized first for developing the equivalent material properties for the composite material. These equivalent properties are employed in the EFEA governing differential equations for representing the composite materials and deriving the element level matrices. The power transmission characteristics at connections between members made out of non-isotropic composite material are considered for deriving suitable power transmission coefficients at junctions of interconnected members. These coefficients are utilized for computing the joint matrix that is needed to assemble the global system of EFEA equations. The global system of EFEA equations is solved numerically and the vibration levels within the entire system can be computed. The new EFEA formulation for modeling composite laminate structures is validated through comparison to test data collected from a representative composite aircraft fuselage that is made out of a composite outer shell and composite frames and stiffeners. NASA Langley constructed the composite cylinder and conducted the test measurements utilized in this work.

Spectral analysis and filter theory in applied geophysics

CERN Document Server

Buttkus, Burkhard

2000-01-01

This book is intended to be an introduction to the fundamentals and methods of spectral analysis and filter theory and their appli­ cations in geophysics. The principles and theoretical basis of the various methods are described, their efficiency and effectiveness eval­ uated, and instructions provided for their practical application. Be­ sides the conventional methods, newer methods arediscussed, such as the spectral analysis ofrandom processes by fitting models to the ob­ served data, maximum-entropy spectral analysis and maximum-like­ lihood spectral analysis, the Wiener and Kalman filtering methods, homomorphic deconvolution, and adaptive methods for nonstation­ ary processes. Multidimensional spectral analysis and filtering, as well as multichannel filters, are given extensive treatment. The book provides a survey of the state-of-the-art of spectral analysis and fil­ ter theory. The importance and possibilities ofspectral analysis and filter theory in geophysics for data acquisition, processing an...

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)

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.

Vibration Analysis Of Automotive Structures Using Holographic Interferometry

Science.gov (United States)

Brown, G. M.; Wales, R. R.

1983-10-01

Since 1979, Ford Motor Company has been developing holographic interferometry to supplement more conventional test methods to measure vehicle component vibrations. An Apollo PHK-1 Double Pulse Holographic Laser System was employed to visualize a variety of complex vibration modes, primarily on current production and prototype powertrain components. Design improvements to reduce powertrain response to problem excitations have been deter-mined through pulsed laser holography, and have, in several cases, been put into production in Ford vehicles. Whole-field definition of vibration related deflections provide continuity of information missed by accelerometer/modal analysis techniaues. Certain opera-tional problems, common among pulsed ruby holographic lasers, have reauired ongoing hardware and electronics improvements to minimize system downtime. Real-time, time-averaged and stroboscopic C. W. laser holographic techniques are being developed at Ford to complement the double pulse capabilities and provide rapid identification of modal frequencies and nodal lines for analysis of powertrain structures. Methods for mounting and exciting powertrains to minimize rigid body motions are discussed. Work at Ford will continue toward development of C. W. holographic techniques to provide refined test methodology dedicated to noise and vibration diagnostics with particular emphasis on semi-automated methods for quantifying displacement and relative phase using high resolution digitized video and computers. Continued use of refined pulsed and CW laser holographic interferometry for the analysis of complex structure vibrations seems assured.

The spectral analysis of cyclo-non-stationary signals

Science.gov (United States)

Abboud, D.; Baudin, S.; Antoni, J.; Rémond, D.; Eltabach, M.; Sauvage, O.

2016-06-01

Condition monitoring of rotating machines in speed-varying conditions remains a challenging task and an active field of research. Specifically, the produced vibrations belong to a particular class of non-stationary signals called cyclo-non-stationary: although highly non-stationary, they contain hidden periodicities related to the shaft angle; the phenomenon of long term modulations is what makes them different from cyclostationary signals which are encountered under constant speed regimes. In this paper, it is shown that the optimal way of describing cyclo-non-stationary signals is jointly in the time and the angular domains. While the first domain describes the waveform characteristics related to the system dynamics, the second one reveals existing periodicities linked to the system kinematics. Therefore, a specific class of signals - coined angle-time cyclostationary is considered, expressing the angle-time interaction. Accordingly, the related spectral representations, the order-frequency spectral correlation and coherence functions are proposed and their efficiency is demonstrated on two industrial cases.

SpectralNET – an application for spectral graph analysis and visualization

Directory of Open Access Journals (Sweden)

Schreiber Stuart L

2005-10-01

Full Text Available Abstract Background Graph theory provides a computational framework for modeling a variety of datasets including those emerging from genomics, proteomics, and chemical genetics. Networks of genes, proteins, small molecules, or other objects of study can be represented as graphs of nodes (vertices and interactions (edges that can carry different weights. SpectralNET is a flexible application for analyzing and visualizing these biological and chemical networks. Results Available both as a standalone .NET executable and as an ASP.NET web application, SpectralNET was designed specifically with the analysis of graph-theoretic metrics in mind, a computational task not easily accessible using currently available applications. Users can choose either to upload a network for analysis using a variety of input formats, or to have SpectralNET generate an idealized random network for comparison to a real-world dataset. Whichever graph-generation method is used, SpectralNET displays detailed information about each connected component of the graph, including graphs of degree distribution, clustering coefficient by degree, and average distance by degree. In addition, extensive information about the selected vertex is shown, including degree, clustering coefficient, various distance metrics, and the corresponding components of the adjacency, Laplacian, and normalized Laplacian eigenvectors. SpectralNET also displays several graph visualizations, including a linear dimensionality reduction for uploaded datasets (Principal Components Analysis and a non-linear dimensionality reduction that provides an elegant view of global graph structure (Laplacian eigenvectors. Conclusion SpectralNET provides an easily accessible means of analyzing graph-theoretic metrics for data modeling and dimensionality reduction. SpectralNET is publicly available as both a .NET application and an ASP.NET web application from http://chembank.broad.harvard.edu/resources/. Source code is

Condition monitoring of PARR-1 rotating machines by vibration analysis technique

Directory of Open Access Journals (Sweden)

Qadir Javed

2014-01-01

Full Text Available Vibration analysis is a key tool for preventive maintenance involving the trending and analysis of machinery performance parameters to detect and identify developing problems before failure and extensive damage can occur. A lab-based experimental setup has been established for obtaining fault-free and fault condition data. After this analysis, primary and secondary motor and pump vibration data of the Pakistan Research Reactor-1 were obtained and analyzed. Vibration signatures were acquired in horizontal, vertical, and axial directions. The 48 vibration signatures have been analyzed to assess the operational status of motors and pumps. The vibration spectrum has been recorded for a 2000 Hz frequency span with a 3200 lines resolution. The data collected should be helpful in future Pakistan Research Reactor-1 condition monitoring.

Vibration analysis of a hydro generator for different operating regimes

Science.gov (United States)

Haţiegan, C.; Pădureanu, I.; Jurcu, M.; Nedeloni, M. D.; Hamat, C. O.; Chioncel, C. P.; Trocaru, S.; Vasile, O.; Bădescu, O.; Micliuc, D.; (Filip Nedeloni, L.; Băra, A.; (Barboni Haţiegan, L.

2017-01-01

Based on experimental measurements, this paper presents the vibration analysis of a hydro generator that equips a Kaplan hydraulic turbine of a Hydropower plant in Romania. This analysis means vibrations measurement to different operating regimes of the hydro generator respectively before installing it and into operation, namely putting off load mode (unexcited and excited) respectively putting on load mode. By comparing, through the experimental results obtained before and after the operation of hydro aggregates are observed vibrations improvements.

Vibration analysis for trending ageing in rotating machinery

International Nuclear Information System (INIS)

Sinha, S.K.; Rama Rao, A.

2006-01-01

The need for condition monitoring system for important equipment and machinery is a growing requirement in every industry and more so in the nuclear power plants because of stringent safety requirements. This is largely because of the inherent benefit of being able to promote predictive maintenance practice rather than uneconomical preventive maintenance practice in the plant. Forerunner among the condition monitoring parameter is vibration signatures measured on a rotating machine. It is known that every moving element in a rotating machine generates vibration signal that is uniquely its own. Detection of such signals and monitoring the changing conditions in a machine through vibration analysis is a technique involving the knowledge of engineering art and the mathematical theory. This blend of sound engineering judgement and vibration data interpretation skill is in fact the basis of vibration diagnostic techniques. (author)

Chromophore-Dependent Intramolecular Exciton-Vibrational Coupling in the FMO Complex: Quantification and Importance for Exciton Dynamics.

Science.gov (United States)

Padula, Daniele; Lee, Myeong H; Claridge, Kirsten; Troisi, Alessandro

2017-11-02

In this paper, we adopt an approach suitable for monitoring the time evolution of the intramolecular contribution to the spectral density of a set of identical chromophores embedded in their respective environments. We apply the proposed method to the Fenna-Matthews-Olson (FMO) complex, with the objective to quantify the differences among site-dependent spectral densities and the impact of such differences on the exciton dynamics of the system. Our approach takes advantage of the vertical gradient approximation to reduce the computational demands of the normal modes analysis. We show that the region of the spectral density that is believed to strongly influence the exciton dynamics changes significantly in the timescale of tens of nanoseconds. We then studied the impact of the intramolecular vibrations on the exciton dynamics by considering a model of FMO in a vibronic basis and neglecting the interaction with the environment to isolate the role of the intramolecular exciton-vibration coupling. In agreement with the assumptions in the literature, we demonstrate that high frequency modes at energy much larger than the excitonic energy splitting have negligible influence on exciton dynamics despite the large exciton-vibration coupling. We also find that the impact of including the site-dependent spectral densities on exciton dynamics is not very significant, indicating that it may be acceptable to apply the same spectral density on all sites. However, care needs to be taken for the description of the exciton-vibrational coupling in the low frequency part of intramolecular modes because exciton dynamics is more susceptible to low frequency modes despite their small Huang-Rhys factors.

Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

International Nuclear Information System (INIS)

Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

2011-01-01

In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Vibrational spectroscopy and principal component analysis for conformational study of virus nucleic acids

Science.gov (United States)

Dovbeshko, G. I.; Repnytska, O. P.; Pererva, T.; Miruta, A.; Kosenkov, D.

2004-07-01

Conformation analysis of mutated DNA-bacteriophages (PLys-23, P23-2, P47- the numbers have been assigned by T. Pererva) induced by MS2 virus incorporated in Ecoli AB 259 Hfr 3000 has been done. Surface enhanced infrared absorption (SEIRA) spectroscopy and principal component analysis has been applied for solving this problem. The nucleic acids isolated from the mutated phages had a form of double stranded DNA with different modifications. The nucleic acid from phage P47 was undergone the structural rearrangement in the most degree. The shape and position ofthe fine structure of the Phosphate asymmetrical band at 1071cm-1 as well as the stretching OH vibration at 3370-3390 cm-1 has indicated to the appearance ofadditional OH-groups. The Z-form feature has been found in the base vibration region (1694 cm-1) and the sugar region (932 cm-1). A supposition about modification of structure of DNA by Z-fragments for P47 phage has been proposed. The P23-2 and PLys-23 phages have showed the numerous minor structural changes also. On the basis of SEIRA spectra we have determined the characteristic parameters of the marker bands of nucleic acid used for construction of principal components. Contribution of different spectral parameters of nucleic acids to principal components has been estimated.

Sum frequency generation vibrational spectroscopy (SFG-VS) for complex molecular surfaces and interfaces: Spectral lineshape measurement and analysis plus some controversial issues

Science.gov (United States)

Wang, Hong-Fei

2016-12-01

Sum-frequency generation vibrational spectroscopy (SFG-VS) was first developed in the 1980s and it has been proven a uniquely sensitive and surface/interface selective spectroscopic probe for characterization of the structure, conformation and dynamics of molecular surfaces and interfaces. In recent years, there have been many progresses in the development of methodology and instrumentation in the SFG-VS toolbox that have significantly broadened the application to complex molecular surfaces and interfaces. In this review, after presenting a unified view on the theory and methodology focusing on the SFG-VS spectral lineshape, as well as the new opportunities in SFG-VS applications with such developments, some of the controversial issues that have been puzzling the community are discussed. The aim of this review is to present to the researchers and students interested in molecular surfaces and interfacial sciences up-to-date perspectives complementary to the existing textbooks and reviews on SFG-VS.

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.

Vibration characteristics analysis for HANARO fuel assembly

International Nuclear Information System (INIS)

Ryu, Jeong Soo; Yoon, Doo Byung

2001-06-01

For investigating the vibration characteristics of HANARO fuel assembly, the finite element models of the in-air fuel assemblies and flow tubes were developed. By calculating the hydrodynamic mass and distributing it on the in-air models, the in-water models of the flow tubes and the fuel assemblies were developed. Then, modal analysis of the developed models was carried out. The analysis results show that the fundamental vibration modes of the in-air 18-element and 36-element fuel assemblies are lateral bending modes and its corresponding natural frequencies are 26.4Hz and 27.7Hz, respectively. The fundamental natural frequency of the in-water 18-element and 36-element fuel assemblies were obtained as 16.1Hz and 16.5Hz. For the verification of the developed finite element models, modal analysis results were compared with those obtained from the modal test. These results demonstrate that the natural frequencies of lower order modes obtained from finite element analysis agree well with those of the modal test and the estimation of the hydrodynamic mass is appropriate. It is expected that the analysis results will be applied as a basic data for the operation and management of the HANARO. In addition, when it is necessary to improve the design of the fuel assembly, the developed finite element models will be utilized as a base model for the vibration characteristic analysis of the modified fuel assembly

Steam turbine coupling misalignment detection by vibrational analysis

International Nuclear Information System (INIS)

Behzad, M.; Asoyesh, M.

2001-01-01

Machinery troubleshooting and diagnostics via vibration analysis have historically been proven, and once again become enlightened topics with the recent popularity of predictive maintenance programs. Among several causes of vibration of turbomachinery, coupling misalignment plays an important role.The results of a theoretical analysis of coupling misalignment and its frequency spectrum characteristics, which can be used for predictive maintenance programs, are compared with other numerical investigations and practical results. The analytical method used in this research is very straightforward and does not need any computer programming

Discussion on Stochastic Analysis of Hydraulic Vibration in Pressurized Water Diversion and Hydropower Systems

Directory of Open Access Journals (Sweden)

Jianxu Zhou

2018-03-01

Full Text Available Hydraulic vibration exists in various water conveyance projects and has resulted in different operating problems, but its obvious effects on system’s pressure head and stable operation have not been definitively addressed in the issued codes for engineering design, especially considering the uncertainties of hydraulic vibration. After detailed analysis of the randomness in hydraulic vibration and the commonly used stochastic approaches, in the basic equations for hydraulic vibration analysis, the random parameters and the formed stochastic equations were discussed for further probabilistic characteristic analysis of the random variables. Furthermore, preliminary investigation of the stochastic analysis of hydraulic vibration in pressurized pipelines and possible self-excited vibration in pumped-storage systems was presented for further consideration. The detailed discussion indicates that it is necessary to conduct further and systematic stochastic analysis of hydraulic vibration. Further, with the obtained frequencies and amplitudes in the form of a probability statement, the stochastic characteristics of various hydraulic vibrations can be investigated in detail and these solutions will be more reasonable for practical applications. Eventually, the stochastic analysis of hydraulic vibration will provide a basic premise to introduce its effect into the engineering design of water diversion and hydropower systems.

Digital spectral analysis parametric, non-parametric and advanced methods

CERN Document Server

Castanié, Francis

2013-01-01

Digital Spectral Analysis provides a single source that offers complete coverage of the spectral analysis domain. This self-contained work includes details on advanced topics that are usually presented in scattered sources throughout the literature.The theoretical principles necessary for the understanding of spectral analysis are discussed in the first four chapters: fundamentals, digital signal processing, estimation in spectral analysis, and time-series models.An entire chapter is devoted to the non-parametric methods most widely used in industry.High resolution methods a

Distributed bearing fault diagnosis based on vibration analysis

Science.gov (United States)

Dolenc, Boštjan; Boškoski, Pavle; Juričić, Đani

2016-01-01

Distributed bearing faults appear under various circumstances, for example due to electroerosion or the progression of localized faults. Bearings with distributed faults tend to generate more complex vibration patterns than those with localized faults. Despite the frequent occurrence of such faults, their diagnosis has attracted limited attention. This paper examines a method for the diagnosis of distributed bearing faults employing vibration analysis. The vibrational patterns generated are modeled by incorporating the geometrical imperfections of the bearing components. Comparing envelope spectra of vibration signals shows that one can distinguish between localized and distributed faults. Furthermore, a diagnostic procedure for the detection of distributed faults is proposed. This is evaluated on several bearings with naturally born distributed faults, which are compared with fault-free bearings and bearings with localized faults. It is shown experimentally that features extracted from vibrations in fault-free, localized and distributed fault conditions form clearly separable clusters, thus enabling diagnosis.

Study on Nonlinear Vibration Analysis of Gear System with Random Parameters

Science.gov (United States)

Tong, Cao; Liu, Xiaoyuan; Fan, Li

2018-03-01

In order to study the dynamic characteristics of gear nonlinear vibration system and the influence of random parameters, firstly, a nonlinear stochastic vibration analysis model of gear 3-DOF is established based on Newton’s Law. And the random response of gear vibration is simulated by stepwise integration method. Secondly, the influence of stochastic parameters such as meshing damping, tooth side gap and excitation frequency on the dynamic response of gear nonlinear system is analyzed by using the stability analysis method such as bifurcation diagram and Lyapunov exponent method. The analysis shows that the stochastic process can not be neglected, which can cause the random bifurcation and chaos of the system response. This study will provide important reference value for vibration engineering designers.

Vibrational Micro-Spectroscopy of Human Tissues Analysis: Review.

Science.gov (United States)

Bunaciu, Andrei A; Hoang, Vu Dang; Aboul-Enein, Hassan Y

2017-05-04

Vibrational spectroscopy (Infrared (IR) and Raman) and, in particular, micro-spectroscopy and micro-spectroscopic imaging have been used to characterize developmental changes in tissues, to monitor these changes in cell cultures and to detect disease and drug-induced modifications. The conventional methods for biochemical and histophatological tissue characterization necessitate complex and "time-consuming" sample manipulations and the results are rarely quantifiable. The spectroscopy of molecular vibrations using mid-IR or Raman techniques has been applied to samples of human tissue. This article reviews the application of these vibrational spectroscopic techniques for analysis of biological tissue published between 2005 and 2015.

Integrated predictive maintenance program vibration and lube oil analysis: Part I - history and the vibration program

Energy Technology Data Exchange (ETDEWEB)

Maxwell, H.

1996-12-01

This paper is the first of two papers which describe the Predictive Maintenance Program for rotating machines at the Palo Verde Nuclear Generating Station. The organization has recently been restructured and significant benefits have been realized by the interaction, or {open_quotes}synergy{close_quotes} between the Vibration Program and the Lube Oil Analysis Program. This paper starts with the oldest part of the program - the Vibration Program and discusses the evolution of the program to its current state. The {open_quotes}Vibration{close_quotes} view of the combined program is then presented.

Laser method of acoustical emission control from vibrating surfaces

Science.gov (United States)

Motyka, Zbigniew

2013-01-01

For limitation of the noise in environment, the necessity occurs of determining and location of sources of sounds emitted from surfaces of many machines and devices, assuring in effect the possibility of suitable constructional changes implementation, targeted at decreasing of their nuisance. In the paper, the results of tests and calculations are presented for plane surface sources emitting acoustic waves. The tests were realized with the use of scanning laser vibrometer which enabled remote registration and the spectral analysis of the surfaces vibrations. The known hybrid digital method developed for determination of sound wave emission from such surfaces divided into small finite elements was slightly modified by distinguishing the phase correlations between such vibrating elements. The final method being developed may find use in wide range of applications for different forms of vibrations of plane surfaces.

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.

Measurements of ground motion and magnet vibrations at the APS

International Nuclear Information System (INIS)

Shiltsev, V.

1996-01-01

This article presents results of ground motion and magnet vibrations measurements at the Advanced Photon Source. The experiments were done over a wide, frequency range (0-05-100 Hz) with the use of SM-3KV-type seismic probes from the Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. Also investigated were magnet vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quadrupole vibrations at different sectors of the ring. The influence of personnel activity in the hall and traffic under the ring on the slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators

Structural and vibrational spectral investigations of melaminium maleate monohydrate by FTIR, FT-Raman and quantum chemical calculations

Science.gov (United States)

Arjunan, V.; Kalaivani, M.; Marchewka, M. K.; Mohan, S.

2013-04-01

The structural investigations of the molecular complex of melamine with maleic acid, namely melaminium maleate monohydrate have been carried out by quantum chemical methods in addition to FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical studies were performed with DFT (B3LYP) method using 6-31G**, cc-pVDZ and 6-311++G** basis sets to determine the energy, structural and thermodynamic parameters of melaminium maleate monohydrate. The hydrogen atom from maleic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak Osbnd H⋯O and Nsbnd H⋯O hydrogen bonds shows notable vibrational effects.

Lateral vibration behavior analysis and TLD vibration absorption design of the soft yoke single-point mooring system

Science.gov (United States)

Lyu, Bai-cheng; Wu, Wen-hua; Yao, Wei-an; Du, Yu

2017-06-01

Mooring system is the key equipment of FPSO safe operation. The soft yoke mooring system is regarded as one of the best shallow water mooring strategies and widely applied to the oil exploitation in the Bohai Bay in China and the Gulf of Mexico. Based on the analysis of numerous monitoring data obtained by the prototype monitoring system of one FPSO in the Bohai Bay, the on-site lateral vibration behaviors found on the site of the soft yoke subject to wave load were analyzed. ADAMS simulation and model experiment were utilized to analyze the soft yoke lateral vibration and it was determined that lateral vibration was resonance behaviors caused by wave excitation. On the basis of the soft yoke longitudinal restoring force being guaranteed, a TLD-based vibration damper system was constructed and the vibration reduction experiments with multi-tank space and multi-load conditions were developed. The experimental results demonstrated that the proposed TLD vibration reduction system can effectively reduce lateral vibration of soft yoke structures.

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.

Vibration analysis of the synchronous motor of a propane compressor

Energy Technology Data Exchange (ETDEWEB)

Nogueira, D.; Rangel Junior, J. de S. [Petroleo Brasileiro S.A. - PETROBRAS, Rio de Janeiro, RJ (Brazil)], Emails: diananogueira@petrobras.com.br, joilson_jr@petrobras.com.br; Moreira, R.G. [Petroleo Brasileiro S.A. - PETROBRAS, Cabiunas, RJ (Brazil)], E-mail: ricgmoreira@petrobras.com.br

2010-07-01

This paper aims at describing the Analysis of a synchronous electric motor which presented high vibration levels (shaft displacement and bearing housing vibration) during the commissioning process, as well as propose the best practices for the solution of vibration problems in similar situations. This motor belongs to the propane centrifugal compressor installed at a Gas Compression Station. The methodology used in this study conducted an investigation of the problems presented in the motor through the execution of many types of tests and the analysis of the results. The main evaluations were performed, such as the vibration analysis and the rotor dynamic analysis. The electric motor was shipped back to the manufacturer's shop, where the manufacturer made certain modifications to the motor structure so as to improve the structure stiffness, such as the improvement of the support and the increase of the thickness of the structural plates. In addition to that, the dynamic balancing of the rotating set was checked. Finally, the excitation at a critical speed close to the rated speed was found after Rotor Dynamics Analysis was performed again, because of the increase in bearing clearances. The bearing shells were replaced so as to increase the separation margin between these frequencies. In order to verify the final condition of the motor, the manufacturer repeated the standard tests - FAT (Factory Acceptance Tests) - according to internal procedure and international standards. As a result of this work, it was possible to conclude that there was a significant increase in the vibration levels due to unbalance conditions. It was also possible to conclude that there are close relationships between high vibration levels and unbalance conditions, as well as between high vibration levels and the stiffness of the system and its support. Certain points of attention related to the manufacturing process of the motor compressor are described at the end of this paper, based

Forced Vibration Analysis for a FGPM Cylindrical Shell

Directory of Open Access Journals (Sweden)

Hong-Liang Dai

2013-01-01

Full Text Available This article presents an analytical study for forced vibration of a cylindrical shell which is composed of a functionally graded piezoelectric material (FGPM. The cylindrical shell is assumed to have two-constituent material distributions through the thickness of the structure, and material properties of the cylindrical shell are assumed to vary according to a power-law distribution in terms of the volume fractions for constituent materials, the exact solution for the forced vibration problem is presented. Numerical results are presented to show the effect of electric excitation, thermal load, mechanical load and volume exponent on the static and force vibration of the FGPM cylindrical shell. The goal of this investigation is to optimize the FGPM cylindrical shell in engineering, also the present solution can be used in the forced vibration analysis of cylindrical smart elements.

System for Monitoring and Analysis of Vibrations at Electric Motors

Directory of Open Access Journals (Sweden)

Gabriela Rață

2014-09-01

Full Text Available The monitoring of vibration occurring at the electric motors is of paramount importance to ensure their optimal functioning. This paper presents a monitoring system of vibrations occurring at two different types of electric motors, using a piezoelectric accelerometer (ICP 603C11 and a data acquisition board from National Instruments (NI 6009. Vibration signals taken from different parts of electric motors are transferred to computer through the acquisition board. A virtual instrument that allows real-time monitoring and Fourier analysis of signals from the vibration sensor was implemented in LabVIEW.

Large amplitude forced vibration analysis of cross-beam system ...

African Journals Online (AJOL)

Large amplitude forced vibration behaviour of cross-beam system under harmonic excitation is studied, incorporating the effect of geometric non-linearity. The forced vibration analysis is carried out in an indirect way, in which the dynamic system is assumed to satisfy the force equilibrium condition at peak load value, thus ...

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.

Digital data acquisition for laser radar for vibration analysis

OpenAIRE

Montes, Felix G.

1998-01-01

Approved for public release; distribution is unlimited Laser radar for vibration analysis represents a military application to develop a target identification system in the future. The problem addressed is how to analyze the vibrations of a target illuminated by the laser radar to achieve a positive identification. This thesis develops a computer-based data acquisition and analysis system for improving the laser radar capability. Specifically, a review is made of the CO2 laser radar, coher...

Vibration and noise analysis in nuclear power plants

International Nuclear Information System (INIS)

1974-12-01

Results of the investigations on noise and vibration analysis are presented as a follow-up study of the work published in ''On-load Surveillance of Nuclear Power Plant Components by Noise and Vibration Analysis'' EUR 5036 e. The state of the art in on-load surveillance techniques of light water reactors is given by extending the preceding studies to investigations of boiling water reactors and by summarizing the latest results of pressurized water reactors, the basis being experimental and theoretical work performed by the different organizations involved in preparing this report. Finally, some developments with respect to measurement and identification methods are discussed

Analysis of whole-body vibration on rheological models for tissues

Science.gov (United States)

Neamţu, A.; Simoiu, D.; Nyaguly, E.; Crastiu, I.; Bereteu, L.

2018-01-01

Whole body vibrations have become a very popular method in recent years, both in physical therapy and in sports. This popularity is due to the fact that, as a result of analyzing the groups of subjects, the effects of small amplitude vibration and low frequency vibration, it was found an increase in the force developed by the feet, a hardening of bone strength or an increase in bone density. In this paper we propose to give a possible explanation of the stress relieving in muscle and/or bone after whole body vibration treatment. To do this we consider some rheological models which after whole body vibrations and after the analysis of their response lead to various experiments.

Measurements of ground motion and magnets vibrations at the APS

International Nuclear Information System (INIS)

Shil'tsev, V.D.

1994-01-01

This article presents results of ground motion and magnets vibrations measurements at the Advanced Photon Source. The experiments were done over wide frequency range 0.05-100 Hz with use of SM-3KV type seismic probes from Budker Institute of Nuclear Physics (Russia). Spectral power densities of vertical and horizontal motions of the APS hall floor and quadrupoles on regular supports were obtained. There were also investigated magnets vibrations induced by designed cooling water flow and spectral characteristics of spatial correlation of the quads vibration at different sectors of the ring. Influence of personnel activity in the hall and traffic under the ring on slow motion of storage ring elements were observed. Amplitudes of vibrations at the APS are compared with results of seismic measurements at some other accelerators. 9 refs.; 10 figs.; 1 tab

Modeling and Analysis of a Combined Stress-Vibration Fiber Bragg Grating Sensor.

Science.gov (United States)

Yao, Kun; Lin, Qijing; Jiang, Zhuangde; Zhao, Na; Tian, Bian; Shi, Peng; Peng, Gang-Ding

2018-03-01

A combined stress-vibration sensor was developed to measure stress and vibration simultaneously based on fiber Bragg grating (FBG) technology. The sensor is composed of two FBGs and a stainless steel plate with a special design. The two FBGs sense vibration and stress and the sensor can realize temperature compensation by itself. The stainless steel plate can significantly increase sensitivity of vibration measurement. Theoretical analysis and Finite Element Method (FEM) were used to analyze the sensor's working mechanism. As demonstrated with analysis, the obtained sensor has working range of 0-6000 Hz for vibration sensing and 0-100 MPa for stress sensing, respectively. The corresponding sensitivity for vibration is 0.46 pm/g and the resulted stress sensitivity is 5.94 pm/MPa, while the nonlinearity error for vibration and stress measurement is 0.77% and 1.02%, respectively. Compared to general FBGs, the vibration sensitivity of this sensor is 26.2 times higher. Therefore, the developed sensor can be used to concurrently detect vibration and stress. As this sensor has height of 1 mm and weight of 1.15 g, it is beneficial for minimization and integration.

Vibration Spectrum Analysis for Indicating Damage on Turbine and Steam Generator Amurang Unit 1

Directory of Open Access Journals (Sweden)

Beny Cahyono

2017-12-01

Full Text Available Maintenance on machines is a mandatory asset management activity to maintain asset reliability in order to reduce losses due to failure. 89% of defects have random failure mode, the proper maintenance method is predictive maintenance. Predictive maintenance object in this research is Steam Generator Amurang Unit 1, which is predictive maintenance is done through condition monitoring in the form of vibration analysis. The conducting vibration analysis on Amurang Unit 1 Steam Generator is because vibration analysis is very effective on rotating objects. Vibration analysis is predicting the damage based on the vibration spectrum, where the vibration spectrum is the result of separating time-based vibrations and simplifying them into vibrations based on their frequency domain. The transformation of time-domain-wave into frequency-domain-wave is using the application of FFT, namely AMS Machinery. The measurement of vibration value is done on turbine bearings and steam generator of Unit 1 Amurang using Turbine Supervisory Instrument and CSI 2600 instrument. The result of this research indicates that vibration spectrum from Unit 1 Amurang Power Plant indicating that there is rotating looseness, even though the vibration value does not require the Unit 1 Amurang Power Plant to stop operating (shut down. This rotating looseness, at some point, can produce some indications that similar with the unbalance. In order to avoid more severe vibrations, it is necessary to do inspection on the bearings in the Amurang Unit 1 Power Plant.

Screw compressor analysis from a vibration point-of-view

Science.gov (United States)

Hübel, D.; Žitek, P.

2017-09-01

Vibrations are a very typical feature of all compressors and are given great attention in the industry. The reason for this interest is primarily the negative influence that it can have on both the operating staff and the entire machine's service life. The purpose of this work is to describe the methodology of screw compressor analysis from a vibration point-of-view. This analysis is an essential part of the design of vibro-diagnostics of screw compressors with regard to their service life.

Structural-Vibration-Response Data Analysis

Science.gov (United States)

Smith, W. R.; Hechenlaible, R. N.; Perez, R. C.

1983-01-01

Computer program developed as structural-vibration-response data analysis tool for use in dynamic testing of Space Shuttle. Program provides fast and efficient time-domain least-squares curve-fitting procedure for reducing transient response data to obtain structural model frequencies and dampings from free-decay records. Procedure simultaneously identifies frequencies, damping values, and participation factors for noisy multiple-response records.

A spectral dynamic stiffness method for free vibration analysis of plane elastodynamic problems

Science.gov (United States)

Liu, X.; Banerjee, J. R.

2017-03-01

A highly efficient and accurate analytical spectral dynamic stiffness (SDS) method for modal analysis of plane elastodynamic problems based on both plane stress and plane strain assumptions is presented in this paper. First, the general solution satisfying the governing differential equation exactly is derived by applying two types of one-dimensional modified Fourier series. Then the SDS matrix for an element is formulated symbolically using the general solution. The SDS matrices are assembled directly in a similar way to that of the finite element method, demonstrating the method's capability to model complex structures. Any arbitrary boundary conditions are represented accurately in the form of the modified Fourier series. The Wittrick-Williams algorithm is then used as the solution technique where the mode count problem (J0) of a fully-clamped element is resolved. The proposed method gives highly accurate solutions with remarkable computational efficiency, covering low, medium and high frequency ranges. The method is applied to both plane stress and plane strain problems with simple as well as complex geometries. All results from the theory in this paper are accurate up to the last figures quoted to serve as benchmarks.

RISK ASSESSMENT BY STRUCTURAL ANALYSIS AND VIBRATION MEASUREMENT EQUIPMENT OPERATING AT OIL FACILITIES

OpenAIRE

Marius STAN

2013-01-01

Vibration analysis applications in operation is one of the diagnostic methods ofoperation of the facility. Analysis of these types of failures indicated the existence of specificfeatures prints and related equipment vibration spectra. Modeling and identification of theseparticular aspects in the spectrum of vibration machines help to control the operation of oilfacilities built safely.

Structural and vibrational spectral investigations of melaminium maleate monohydrate by FTIR, FT-Raman and quantum chemical calculations.

Science.gov (United States)

Arjunan, V; Kalaivani, M; Marchewka, M K; Mohan, S

2013-04-15

The structural investigations of the molecular complex of melamine with maleic acid, namely melaminium maleate monohydrate have been carried out by quantum chemical methods in addition to FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical studies were performed with DFT (B3LYP) method using 6-31G(**), cc-pVDZ and 6-311++G(**) basis sets to determine the energy, structural and thermodynamic parameters of melaminium maleate monohydrate. The hydrogen atom from maleic acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak OH···O and NH···O hydrogen bonds shows notable vibrational effects. Copyright © 2013 Elsevier B.V. All rights reserved.

Basic Functional Analysis Puzzles of Spectral Flow

DEFF Research Database (Denmark)

Booss-Bavnbek, Bernhelm

2011-01-01

We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles.......We explain an array of basic functional analysis puzzles on the way to general spectral flow formulae and indicate a direction of future topological research for dealing with these puzzles....

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

Substitution dynamical systems spectral analysis

CERN Document Server

Queffélec, Martine

2010-01-01

This volume mainly deals with the dynamics of finitely valued sequences, and more specifically, of sequences generated by substitutions and automata. Those sequences demonstrate fairly simple combinatorical and arithmetical properties and naturally appear in various domains. As the title suggests, the aim of the initial version of this book was the spectral study of the associated dynamical systems: the first chapters consisted in a detailed introduction to the mathematical notions involved, and the description of the spectral invariants followed in the closing chapters. This approach, combined with new material added to the new edition, results in a nearly self-contained book on the subject. New tools - which have also proven helpful in other contexts - had to be developed for this study. Moreover, its findings can be concretely applied, the method providing an algorithm to exhibit the spectral measures and the spectral multiplicity, as is demonstrated in several examples. Beyond this advanced analysis, many...

SPAM- SPECTRAL ANALYSIS MANAGER (DEC VAX/VMS VERSION)

Science.gov (United States)

Solomon, J. E.

1994-01-01

The Spectral Analysis Manager (SPAM) was developed to allow easy qualitative analysis of multi-dimensional imaging spectrometer data. Imaging spectrometers provide sufficient spectral sampling to define unique spectral signatures on a per pixel basis. Thus direct material identification becomes possible for geologic studies. SPAM provides a variety of capabilities for carrying out interactive analysis of the massive and complex datasets associated with multispectral remote sensing observations. In addition to normal image processing functions, SPAM provides multiple levels of on-line help, a flexible command interpretation, graceful error recovery, and a program structure which can be implemented in a variety of environments. SPAM was designed to be visually oriented and user friendly with the liberal employment of graphics for rapid and efficient exploratory analysis of imaging spectrometry data. SPAM provides functions to enable arithmetic manipulations of the data, such as normalization, linear mixing, band ratio discrimination, and low-pass filtering. SPAM can be used to examine the spectra of an individual pixel or the average spectra over a number of pixels. SPAM also supports image segmentation, fast spectral signature matching, spectral library usage, mixture analysis, and feature extraction. High speed spectral signature matching is performed by using a binary spectral encoding algorithm to separate and identify mineral components present in the scene. The same binary encoding allows automatic spectral clustering. Spectral data may be entered from a digitizing tablet, stored in a user library, compared to the master library containing mineral standards, and then displayed as a timesequence spectral movie. The output plots, histograms, and stretched histograms produced by SPAM can be sent to a lineprinter, stored as separate RGB disk files, or sent to a Quick Color Recorder. SPAM is written in C for interactive execution and is available for two different

RISK ASSESSMENT BY STRUCTURAL ANALYSIS AND VIBRATION MEASUREMENT EQUIPMENT OPERATING AT OIL FACILITIES

Directory of Open Access Journals (Sweden)

Marius STAN

2013-05-01

Full Text Available Vibration analysis applications in operation is one of the diagnostic methods ofoperation of the facility. Analysis of these types of failures indicated the existence of specificfeatures prints and related equipment vibration spectra. Modeling and identification of theseparticular aspects in the spectrum of vibration machines help to control the operation of oilfacilities built safely.

Vibrational Energy Distribution Analysis (VEDA): Scopes and limitations

Science.gov (United States)

Jamróz, Michał H.

2013-10-01

The principle of operations of the VEDA program written by the author for Potential Energy Distribution (PED) analysis of theoretical vibrational spectra is described. Nowadays, the PED analysis is indispensible tool in serious analysis of the vibrational spectra. To perform the PED analysis it is necessary to define 3N-6 linearly independent local mode coordinates. Already for 20-atomic molecules it is a difficult task. The VEDA program reads the input data automatically from the Gaussian program output files. Then, VEDA automatically proposes an introductory set of local mode coordinates. Next, the more adequate coordinates are proposed by the program and optimized to obtain maximal elements of each column (internal coordinate) of the PED matrix (the EPM parameter). The possibility for an automatic optimization of PED contributions is a unique feature of the VEDA program absent in any other programs performing PED analysis.

Statistical evaluation of vibration analysis techniques

Science.gov (United States)

Milner, G. Martin; Miller, Patrice S.

1987-01-01

An evaluation methodology is presented for a selection of candidate vibration analysis techniques applicable to machinery representative of the environmental control and life support system of advanced spacecraft; illustrative results are given. Attention is given to the statistical analysis of small sample experiments, the quantification of detection performance for diverse techniques through the computation of probability of detection versus probability of false alarm, and the quantification of diagnostic performance.

Particulate characterization by PIXE multivariate spectral analysis

International Nuclear Information System (INIS)

Antolak, Arlyn J.; Morse, Daniel H.; Grant, Patrick G.; Kotula, Paul G.; Doyle, Barney L.; Richardson, Charles B.

2007-01-01

Obtaining particulate compositional maps from scanned PIXE (proton-induced X-ray emission) measurements is extremely difficult due to the complexity of analyzing spectroscopic data collected with low signal-to-noise at each scan point (pixel). Multivariate spectral analysis has the potential to analyze such data sets by reducing the PIXE data to a limited number of physically realizable and easily interpretable components (that include both spectral and image information). We have adapted the AXSIA (automated expert spectral image analysis) program, originally developed by Sandia National Laboratories to quantify electron-excited X-ray spectroscopy data, for this purpose. Samples consisting of particulates with known compositions and sizes were loaded onto Mylar and paper filter substrates and analyzed by scanned micro-PIXE. The data sets were processed by AXSIA and the associated principal component spectral data were quantified by converting the weighting images into concentration maps. The results indicate automated, nonbiased, multivariate statistical analysis is useful for converting very large amounts of data into a smaller, more manageable number of compositional components needed for locating individual particles-of-interest on large area collection media

Functional analysis, spectral theory, and applications

CERN Document Server

Einsiedler, Manfred

2017-01-01

This textbook provides a careful treatment of functional analysis and some of its applications in analysis, number theory, and ergodic theory. In addition to discussing core material in functional analysis, the authors cover more recent and advanced topics, including Weyl’s law for eigenfunctions of the Laplace operator, amenability and property (T), the measurable functional calculus, spectral theory for unbounded operators, and an account of Tao’s approach to the prime number theorem using Banach algebras. The book further contains numerous examples and exercises, making it suitable for both lecture courses and self-study. Functional Analysis, Spectral Theory, and Applications is aimed at postgraduate and advanced undergraduate students with some background in analysis and algebra, but will also appeal to everyone with an interest in seeing how functional analysis can be applied to other parts of mathematics.

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

Mechanical vibration and shock analysis, sinusoidal vibration

CERN Document Server

Lalanne, Christian

2014-01-01

Everything engineers need to know about mechanical vibration and shock...in one authoritative reference work! This fully updated and revised 3rd edition addresses the entire field of mechanical vibration and shock as one of the most important types of load and stress applied to structures, machines and components in the real world. Examples include everything from the regular and predictable loads applied to turbines, motors or helicopters by the spinning of their constituent parts to the ability of buildings to withstand damage from wind loads or explosions, and the need for cars to m

Mathematical formulation of temperature fluctuation and control rod vibration in PARR

International Nuclear Information System (INIS)

Ansari, S.A.; Ayazuddin, S.K.

This report describes the mathematical interpretation of experimental neutron noise spectra obtained for PARR core. A one dimensional thermal-hydraulic model of PARR core was developed to calculate the magnitude of neutron noise as a result of fluctuation in the core inlet coolant temperature. The sink structure of the neutron power spectral density as well as the dependence of observed neutron spectra on coolant velocity is also explained by the thermal hydraulic model. An attempt is made to explain the phenomena of control rod vibration by a simple eigen frequency vibration model. The calculated neutron power spectral density due to vibration and temperature noise were added and compared with the experimental power spectra obtained for PARR. (orig./A.B.)

An experimental approach to free vibration analysis of smart composite beam

Science.gov (United States)

Yashavantha Kumar, G. A.; Sathish Kumar, K. M.

2018-02-01

Experimental vibration analysis is a main concern of this study. In designing any structural component the important parameter that has to be considered is vibration. The present work involves the experimental investigation of free vibration analysis of a smart beam. Smart beam consists of glass/epoxy composite as a main substrate and two PZT patches. The PZT patches are glued above and below the main beam. By experimentation the natural frequencies and mode shapes are obtained for both with and without PZT patches of a beam. Finally through experimentation the response of the smart beam is recorded.

Analysis of fluid induced vibration of cryogenic pipes in consideration of the cooling effect

International Nuclear Information System (INIS)

Kim, Bong Soo; Kim, Young Ki; Choi, Jung Woon

2008-01-01

The purpose of system analysis using fluid induced vibration is to identify the problems of the system in advance by analyzing the vibration behavior of the system excited by fluid flow. Fluid-induced vibration analysis methods, developed so far, generally use the numerical analysis method to analyze the fluid flowing inside the pipe and the infinitesimal elements at normal temperature on the basis of the governing equation obtained by applying Newton's Second Law and the momentum equation. However, as the fluid temperature changes greatly at low temperature, fluid-induced vibration analysis methods for normal temperature cannot be applied. This study investigated methods of analyzing fluid-induced vibration in consideration of the cooling effect. In consideration of the changes in the properties of the fluid and system relative to temperature, vibration behavior was analyzed numerically by means of the equation of motion. As a result, the natural frequency of the system tends to change because of the changes of the properties of materials even when the flux is constant inside the pipe, and the vibration behavior of the system was compared to that in case of normal temperature to analyze how much influence the cooling effect has on the vibration behavior of the system

Vibrational Spectroscopies and Chemometry for Nondestructive Identification and Differentiation of Painting Binders

Directory of Open Access Journals (Sweden)

Serena Carlesi

2017-01-01

Full Text Available A comprehensive dataset of vibrational spectra of different natural organic binding media is presented and discussed. The binding media were applied on a glass substrate and analyzed after three months of natural ageing. The combination of Raman and FT-NIR spectroscopies allows for an improved identification of these materials as Raman technique is more informative about the skeletal vibrations, while FT-NIR spectroscopy is more sensitive to the substituents and polar groups. The experimental results are initially discussed in the framework of current spectral assignment. Then, multivariate analysis (PCA is applied leading to differentiation among the samples. The two major principal components allow for a complete separation of the different classes of organic materials. Further differentiation within the same class is possible thanks to the secondary components. The loadings obtained from PCA are discussed on the basis of the spectral assignment leading to clear understanding of the physical basis of this differentiation process.

Petroleum Pumps’ Current and Vibration Signatures Analysis Using Wavelet Coherence Technique

Directory of Open Access Journals (Sweden)

Rmdan Shnibha

2013-01-01

Full Text Available Vibration analysis is widely used for rotating machinery diagnostics; however measuring vibration of operational oil well pumps is not possible. The pump’s driver’s current signatures may provide condition-related information without the need for an access to the pump itself. This paper investigates the degree of relationship between the pump’s driver’s current signatures and its induced vibration. This relationship between the driver’s current signatures (DCS and its vibration signatures (DVS is studied by calculating magnitude-squared coherence and phase coherence parameters at a certain frequency band using continuous wavelet transform (CWT. The CWT coherence-based technique allows better analysis of temporal evolution of the frequency content of dynamic signals and areas in the time-frequency plane where the two signals exhibit common power or consistent phase behaviour indicating a relationship between the signals. This novel approach is validated by experimental data acquired from 3 kW petroleum pump’s driver. Both vibration and current signatures were acquired under different speed and load conditions. The outcomes of this research suggest the use of DCS analysis as reliable and inexpensive condition monitoring tool, which could be implemented for oil pumps, real-time monitoring associated with condition-based maintenance (CBM program.

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.

General vibration monitoring: Experimental hall

International Nuclear Information System (INIS)

Jendrzejczyk, J.A.; Wambsganss, M.W.; Smith, R.K.

1993-01-01

The reported vibration data were generated from measurements made on the experimental hall floor on December 2, 1992. At the time of the measurements, the ESRF hydrolevel was set-up in the Early Assembly Area (EAA) of the experimental hall and was being used to measure static displacement (settlement) of the floor. The vibration measurement area was on and adjacent to the EAA, in the vicinity of the ESRF hydrolevel test which was in progress. This report summarizes the objectives, instrumentation, measurement locations, observations, and conclusions, and provides selected results in the form of RMS vs. time plots, and power spectral densities from which frequency information can be derived. Measured response amplitudes were within the vibration criteria established for the APS

Group-theoretical and topological analysis of localized rotation-vibration states

International Nuclear Information System (INIS)

Sadovskii, D.A.; Zhilinskii, B.I.

1993-01-01

A general scheme of qualitative analysis is applied to molecular rovibrational problems. The classical-quantum correspondence provides a description of different classes of localized quantum rotation-vibration states associated with localized classical motion. A description of qualitative features, such as localized motion, and of qualitative changes, such as localization phenomena, is based on the concept of the simplest Hamiltonian. It uses only the topological properties of the compact reduced phase space and the action of the symmetry group on this space. The qualitative changes of the simplest Hamiltonian are analyzed as bifurcations caused by rotational or vibrational excitation. The relation between the stationary points of the classical Hamiltonian function on the reduced phase space and the principal periodic trajectories in the coordinate space is analyzed for vibrational Hamiltonians. In particular, the relation between the nonlinear normal modes, proposed by Montaldi, Roberts, and Stewart [Philos. Trans. R. Soc. London, Ser. A 325, 237 (1988)], and normal- and local-mode models widely used in molecular physics is discussed. Along with a general consideration of localized rotational and vibrational states a more detailed analysis of the vibrational dynamics of an X 3 molecule with the D 3h symmetry, such as the H 3 + molecular ion, is given

Multivariate Analysis of Ladle Vibration

Science.gov (United States)

Yenus, Jaefer; Brooks, Geoffrey; Dunn, Michelle

2016-08-01

The homogeneity of composition and uniformity of temperature of the steel melt before it is transferred to the tundish are crucial in making high-quality steel product. The homogenization process is performed by stirring the melt using inert gas in ladles. Continuous monitoring of this process is important to make sure the action of stirring is constant throughout the ladle. Currently, the stirring process is monitored by process operators who largely rely on visual and acoustic phenomena from the ladle. However, due to lack of measurable signals, the accuracy and suitability of this manual monitoring are problematic. The actual flow of argon gas to the ladle may not be same as the flow gage reading due to leakage along the gas line components. As a result, the actual degree of stirring may not be correctly known. Various researchers have used one-dimensional vibration, and sound and image signals measured from the ladle to predict the degree of stirring inside. They developed online sensors which are indeed to monitor the online stirring phenomena. In this investigation, triaxial vibration signals have been measured from a cold water model which is a model of an industrial ladle. Three flow rate ranges and varying bath heights were used to collect vibration signals. The Fast Fourier Transform was applied to the dataset before it has been analyzed using principal component analysis (PCA) and partial least squares (PLS). PCA was used to unveil the structure in the experimental data. PLS was mainly applied to predict the stirring from the vibration response. It was found that for each flow rate range considered in this study, the informative signals reside in different frequency ranges. The first latent variables in these frequency ranges explain more than 95 pct of the variation in the stirring process for the entire single layer and the double layer data collected from the cold model. PLS analysis in these identified frequency ranges demonstrated that the latent

Current applications of vibration monitoring and neutron noise analysis

International Nuclear Information System (INIS)

Damiano, B.; Kryter, R.C.

1990-02-01

Monitoring programs using vibration monitoring or neutron noise analysis have demonstrated the ability to detect and, in some cases, diagnose the nature of reactor vessel internals structural degradation. Detection of compromised mechanical integrity of reactor vessel internal components in its early stages allows corrective action to be taken before weakening or damage occurs. In addition to the economic benefits early detection and correction can provide, they can also help maintain plant safety. Information on the condition of reactor vessel internal components gained from a monitoring program supplements in-service inspection results and may be useful in justifying plant license extension. This report, which was prepared under the Nuclear Plant Aging Research Program sponsored by the US Nuclear Regulatory Commission, discusses the application of vibration monitoring and neutron noise analysis for monitoring light-water reactor vessel internals. The report begins by describing the effects of structural integrity loss on internals vibration and how measurable parameters can be used to detect and track the progress of degradation. This is followed by a description and comparison of vibration monitoring and neutron noise analysis, two methods for monitoring the mechanical integrity of reactor vessel internals condition monitoring programs in the United States, Federal Republic of Germany, and France, three countries having substantial commitments to nuclear power. The last section presents guidelines for US utilities wishing to establish reactor internals condition monitoring programs. 20 refs., 5 figs., 4 tabs

Spectral analysis of the stick-slip phenomenon in "oral" tribological texture evaluation.

Science.gov (United States)

Sanahuja, Solange; Upadhyay, Rutuja; Briesen, Heiko; Chen, Jianshe

2017-08-01

"Oral" tribology has become a new paradigm in food texture studies to understand complex texture attributes, such as creaminess, oiliness, and astringency, which could not be successfully characterized by traditional texture analysis nor by rheology. Stick-slip effects resulting from intermittent sliding motion during kinetic friction of oral mucosa could constitute an additional determining factor of sensory perception where traditional friction coefficient values and their Stribeck regimes fail in predicting different lubricant (food bolus and saliva) behaviors. It was hypothesized that the observed jagged behavior of most sliding force curves are due to stick-slip effects and depend on test velocity, normal load, surface roughness as well as lubricant type. Therefore, different measurement set-ups were investigated: sliding velocities from 0.01 to 40 mm/s, loads of 0.5 and 2.5 N as well as a smooth and a textured silicone contact surface. Moreover, dry contact measurements were compared to model food systems, such as water, oil, and oil-in-water emulsions. Spectral analysis permitted to extract the distribution of stick-slip magnitudes for specific wave numbers, characterizing the occurrence of jagged force peaks per unit sliding distance, similar to frequencies per unit time. The spectral features were affected by all the above mentioned tested factors. Stick-slip created vibration frequencies in the range of those detected by oral mechanoreceptors (0.3-400 Hz). The study thus provides a new insight into the use of tribology in food psychophysics. Dynamic spectral analysis has been applied for the first time to the force-displacement curves in "oral" tribology. Analyzing the stick-slip phenomenon in the dynamic friction provides new information that is generally overlooked or confused with machine noise and which may help to understand friction-related sensory attributes. This approach allows us to differentiate samples that have similar friction coefficient

Road simulation for four-wheel vehicle whole input power spectral density

Science.gov (United States)

Wang, Jiangbo; Qiang, Baomin

2017-05-01

As the vibration of running vehicle mainly comes from road and influence vehicle ride performance. So the road roughness power spectral density simulation has great significance to analyze automobile suspension vibration system parameters and evaluate ride comfort. Firstly, this paper based on the mathematical model of road roughness power spectral density, established the integral white noise road random method. Then in the MATLAB/Simulink environment, according to the research method of automobile suspension frame from simple two degree of freedom single-wheel vehicle model to complex multiple degrees of freedom vehicle model, this paper built the simple single incentive input simulation model. Finally the spectrum matrix was used to build whole vehicle incentive input simulation model. This simulation method based on reliable and accurate mathematical theory and can be applied to the random road simulation of any specified spectral which provides pavement incentive model and foundation to vehicle ride performance research and vibration simulation.

Spectral theory and nonlinear functional analysis

CERN Document Server

Lopez-Gomez, Julian

2001-01-01

This Research Note addresses several pivotal problems in spectral theory and nonlinear functional analysis in connection with the analysis of the structure of the set of zeroes of a general class of nonlinear operators. It features the construction of an optimal algebraic/analytic invariant for calculating the Leray-Schauder degree, new methods for solving nonlinear equations in Banach spaces, and general properties of components of solutions sets presented with minimal use of topological tools. The author also gives several applications of the abstract theory to reaction diffusion equations and systems.The results presented cover a thirty-year period and include recent, unpublished findings of the author and his coworkers. Appealing to a broad audience, Spectral Theory and Nonlinear Functional Analysis contains many important contributions to linear algebra, linear and nonlinear functional analysis, and topology and opens the door for further advances.

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.

[Analysis of sensitive spectral bands for burning status detection using hyper-spectral images of Tiangong-01].

Science.gov (United States)

Qin, Xian-Lin; Zhu, Xi; Yang, Fei; Zhao, Kai-Rui; Pang, Yong; Li, Zeng-Yuan; Li, Xu-Zhi; Zhang, Jiu-Xing

2013-07-01

To obtain the sensitive spectral bands for detection of information on 4 kinds of burning status, i. e. flaming, smoldering, smoke, and fire scar, with satellite data, analysis was conducted to identify suitable satellite spectral bands for detection of information on these 4 kinds of burning status by using hyper-spectrum images of Tiangong-01 (TG-01) and employing a method combining statistics and spectral analysis. The results show that: in the hyper-spectral images of TG-01, the spectral bands differ obviously for detection of these 4 kinds of burning status; in all hyper-spectral short-wave infrared channels, the reflectance of flaming is higher than that of all other 3 kinds of burning status, and the reflectance of smoke is the lowest; the reflectance of smoke is higher than that of all other 3 kinds of burning status in the channels corresponding to hyper-spectral visible near-infrared and panchromatic sensors. For spectral band selection, more suitable spectral bands for flaming detection are 1 000.0-1 956.0 and 2 020.0-2 400.0 nm; the suitable spectral bands for identifying smoldering are 930.0-1 000.0 and 1 084.0-2 400.0 nm; the suitable spectral bands for smoke detection is in 400.0-920.0 nm; for fire scar detection, it is suitable to select bands with central wavelengths of 900.0-930.0 and 1 300.0-2 400.0 nm, and then to combine them to construct a detection model.

Vibration Finite Element Analysis of SC10 Dry-type Transformer Core

Directory of Open Access Journals (Sweden)

Gao Sheng Wei

2014-06-01

Full Text Available As the popularization and application of dry-type power transformer, its work when the vibration noise problem widely concerned, on the basis of time-varying electromagnetic field and structural mechanics equation, this paper established a finite element analysis model of dry-type transformer, through the electromagnetic field – Structural mechanics field – sound field more than physical field coupling calculation analysis, obtained in no load and the vibration modes of the core under different load and frequency. According to the transformer vibration mechanism, compared with the experimental data, verified the accuracy of the calculation results, as the core of how to provide the theory foundation and to reduce the noise of the experiment.

On Holo-Hilbert spectral analysis: a full informational spectral representation for nonlinear and non-stationary data

OpenAIRE

Huang, Norden E.; Hu, Kun; Yang, Albert C. C.; Chang, Hsing-Chih; Jia, Deng; Liang, Wei-Kuang; Yeh, Jia Rong; Kao, Chu-Lan; Juan, Chi-Hung; Peng, Chung Kang; Meijer, Johanna H.; Wang, Yung-Hung; Long, Steven R.; Wu, Zhauhua

2016-01-01

The Holo-Hilbert spectral analysis (HHSA) method is introduced to cure the deficiencies of traditional spectral analysis and to give a full informational representation of nonlinear and non-stationary data. It uses a nested empirical mode decomposition and Hilbert–Huang transform (HHT) approach to identify intrinsic amplitude and frequency modulations often present in nonlinear systems. Comparisons are first made with traditional spectrum analysis, which usually achieved its results through c...

Dynamics and vibrations progress in nonlinear analysis

CERN Document Server

Kachapi, Seyed Habibollah Hashemi

2014-01-01

Dynamical and vibratory systems are basically an application of mathematics and applied sciences to the solution of real world problems. Before being able to solve real world problems, it is necessary to carefully study dynamical and vibratory systems and solve all available problems in case of linear and nonlinear equations using analytical and numerical methods. It is of great importance to study nonlinearity in dynamics and vibration; because almost all applied processes act nonlinearly, and on the other hand, nonlinear analysis of complex systems is one of the most important and complicated tasks, especially in engineering and applied sciences problems. There are probably a handful of books on nonlinear dynamics and vibrations analysis. Some of these books are written at a fundamental level that may not meet ambitious engineering program requirements. Others are specialized in certain fields of oscillatory systems, including modeling and simulations. In this book, we attempt to strike a balance between th...

Vibrational analysis of Fourier transform spectrum of the B u )–X g ...

Indian Academy of Sciences (India)

improved by putting the wave number of band origins in Deslandre table. The vibrational analysis was supported by determining the Franck–Condon factor and r-centroid values. Keywords. Fourier transform spectroscopy; electronic spectrum of selenium dimer; vibrational analysis; Franck–Condon factor; r-centroid values.

Fluid-Induced Vibration Analysis for Reactor Internals Using Computational FSI Method

Energy Technology Data Exchange (ETDEWEB)

Moon, Jong Sung; Yi, Kun Woo; Sung, Ki Kwang; Im, In Young; Choi, Taek Sang [KEPCO E and C, Daejeon (Korea, Republic of)

2013-10-15

This paper introduces a fluid-induced vibration analysis method which calculates the response of the RVI to both deterministic and random loads at once and utilizes more realistic pressure distribution using the computational Fluid Structure Interaction (FSI) method. As addressed above, the FIV analysis for the RVI was carried out using the computational FSI method. This method calculates the response to deterministic and random turbulence loads at once. This method is also a simple and integrative method to get structural dynamic responses of reactor internals to various flow-induced loads. Because the analysis of this paper omitted the bypass flow region and Inner Barrel Assembly (IBA) due to the limitation of computer resources, it is necessary to find an effective way to consider all regions in the RV for the FIV analysis in the future. Reactor coolant flow makes Reactor Vessel Internals (RVI) vibrate and may affect the structural integrity of them. U. S. NRC Regulatory Guide 1.20 requires the Comprehensive Vibration Assessment Program (CVAP) to verify the structural integrity of the RVI for Fluid-Induced Vibration (FIV). The hydraulic forces on the RVI of OPR1000 and APR1400 were computed from the hydraulic formulas and the CVAP measurements in Palo Verde Unit 1 and Yonggwang Unit 4 for the structural vibration analyses. In this method, the hydraulic forces were divided into deterministic and random turbulence loads and were used for the excitation forces of the separate structural analyses. These forces are applied to the finite element model and the responses to them were combined into the resultant stresses.

Coupled thermal, structural and vibrational analysis of a hypersonic engine for flight test

Energy Technology Data Exchange (ETDEWEB)

Sook-Ying, Ho [Defence Science and Technology Organisation, SA (Australia); Paull, A. [Queensland Univ., Dept. of Mechanical Engineering (Australia)

2006-07-15

This paper describes a relatively simple and quick method for implementing aerodynamic heating models into a finite element code for non-linear transient thermal-structural and thermal-structural-vibrational analyses of a Mach 10 generic HyShot scram-jet engine. The thermal-structural-vibrational response of the engine was studied for the descent trajectory from 60 to 26 km. Aerodynamic heating fluxes, as a function of spatial position and time for varying trajectory points, were implemented in the transient heat analysis. Additionally, the combined effect of varying dynamic pressure and thermal loads with altitude was considered. This aero-thermal-structural analysis capability was used to assess the temperature distribution, engine geometry distortion and yielding of the structural material due to aerodynamic heating during the descent trajectory, and for optimising the wall thickness, nose radius of leading edge, etc. of the engine intake. A structural vibration analysis was also performed following the aero-thermal-structural analysis to determine the changes in natural frequencies of the structural vibration modes that occur at the various temperatures associated with the descent trajectory. This analysis provides a unique and relatively simple design strategy for predicting and mitigating the thermal-structural-vibrational response of hypersonic engines. (authors)

Structural and vibrational spectral investigations of melaminium glutarate monohydrate by FTIR, FT-Raman and DFT methods

Science.gov (United States)

Arjunan, V.; Marchewka, M. K.; Raj, Arushma; Yang, Haifeng; Mohan, S.

2015-01-01

Melaminium glutarate monohydrate has been synthesised and FTIR and FT-Raman spectral investigations are carried out. The molecular geometry and vibrational frequencies of melaminium glutarate monohydrate in the ground state have been determined by using B3LYP method with 6-31++G**, 6-31++G and cc-pVDZ basis sets. The stability of the system, inter molecular hydrogen bonding and the electron donor-acceptor interactions of the complex have been investigated by using natural bonding orbital analysis. It reveals that the Nsbnd H⋯O and Osbnd H⋯O intermolecular interactions significantly influence crystal packing of this molecular complex. The glutarate anion forms hydrogen bonds to the melaminium cation as the proton donor of the type Nsbnd H⋯O with a distance (N⋯O) = 2.51 Å. It is also linked by other hydrogen bonds to the water molecule of the type Osbnd H⋯O with (O⋯O) = 2.82 Å and to the amino (sbnd NH2) group of melaminium cation of the type Nsbnd H⋯O with (N⋯O) = 2.82 Å as the proton acceptor. The electrostatic potential of the complex is in the range +1.892e × 10-2 to -1.892e × 10-2. The limits of total electron density of the complex is +6.679e × 10-2 to -6.679e × 10-2.

Structural and vibrational spectral investigations of melaminium glutarate monohydrate by FTIR, FT-Raman and DFT methods.

Science.gov (United States)

Arjunan, V; Marchewka, M K; Raj, Arushma; Yang, Haifeng; Mohan, S

2015-01-25

Melaminium glutarate monohydrate has been synthesised and FTIR and FT-Raman spectral investigations are carried out. The molecular geometry and vibrational frequencies of melaminium glutarate monohydrate in the ground state have been determined by using B3LYP method with 6-31++G(**), 6-31++G and cc-pVDZ basis sets. The stability of the system, inter molecular hydrogen bonding and the electron donor-acceptor interactions of the complex have been investigated by using natural bonding orbital analysis. It reveals that the N-H⋯O and O-H⋯O intermolecular interactions significantly influence crystal packing of this molecular complex. The glutarate anion forms hydrogen bonds to the melaminium cation as the proton donor of the type N-H⋯O with a distance (N⋯O)=2.51 Å. It is also linked by other hydrogen bonds to the water molecule of the type O-H⋯O with (O⋯O)=2.82 Å and to the amino (NH2) group of melaminium cation of the type N-H⋯O with (N⋯O)=2.82 Å as the proton acceptor. The electrostatic potential of the complex is in the range +1.892e×10(-2) to -1.892e×10(-2). The limits of total electron density of the complex is +6.679e×10(-2) to -6.679e×10(-2). Copyright © 2014 Elsevier B.V. All rights reserved.

Shunted Piezoelectric Vibration Damping Analysis Including Centrifugal Loading Effects

Science.gov (United States)

Min, James B.; Duffy, Kirsten P.; Provenza, Andrew J.

2011-01-01

Excessive vibration of turbomachinery blades causes high cycle fatigue problems which require damping treatments to mitigate vibration levels. One method is the use of piezoelectric materials as passive or active dampers. Based on the technical challenges and requirements learned from previous turbomachinery rotor blades research, an effort has been made to investigate the effectiveness of a shunted piezoelectric for the turbomachinery rotor blades vibration control, specifically for a condition with centrifugal rotation. While ample research has been performed on the use of a piezoelectric material with electric circuits to attempt to control the structural vibration damping, very little study has been done regarding rotational effects. The present study attempts to fill this void. Specifically, the objectives of this study are: (a) to create and analyze finite element models for harmonic forced response vibration analysis coupled with shunted piezoelectric circuits for engine blade operational conditions, (b) to validate the experimental test approaches with numerical results and vice versa, and (c) to establish a numerical modeling capability for vibration control using shunted piezoelectric circuits under rotation. Study has focused on a resonant damping control using shunted piezoelectric patches on plate specimens. Tests and analyses were performed for both non-spinning and spinning conditions. The finite element (FE) shunted piezoelectric circuit damping simulations were performed using the ANSYS Multiphysics code for the resistive and inductive circuit piezoelectric simulations of both conditions. The FE results showed a good correlation with experimental test results. Tests and analyses of shunted piezoelectric damping control, demonstrating with plate specimens, show a great potential to reduce blade vibrations under centrifugal loading.

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.

Nonlinear physical systems spectral analysis, stability and bifurcations

CERN Document Server

Kirillov, Oleg N

2013-01-01

Bringing together 18 chapters written by leading experts in dynamical systems, operator theory, partial differential equations, and solid and fluid mechanics, this book presents state-of-the-art approaches to a wide spectrum of new and challenging stability problems.Nonlinear Physical Systems: Spectral Analysis, Stability and Bifurcations focuses on problems of spectral analysis, stability and bifurcations arising in the nonlinear partial differential equations of modern physics. Bifurcations and stability of solitary waves, geometrical optics stability analysis in hydro- and magnetohydrodynam

Experimental Analysis of Mast Lifting and Bending Forces on Vibration Patterns Before and After Pinion Reinstallation in an OH-58 Transmission Test Rig

Science.gov (United States)

Huff, Edward M.; Lewicki, David G.; Tumer, Irem Y.; Decker, Harry; Barszez, Eric; Zakrajsek, James J.; Norvig, Peter (Technical Monitor)

2000-01-01

As part of a collaborative research program between NASA Ames Research Center (ARC), NASA Glenn Research Center (GRC), and the US Army Laboratory, a series of experiments is being performed in GRC's 500 HP OH-58 Transmission Test Rig facility and ARC's AH-I Cobra and OH-58c helicopters. The findings reported in this paper were drawn from Phase-I of a two-phase test-rig experiment, and are focused on the vibration response of an undamaged pinion gear operating in the transmission test rig. To simulate actual flight conditions, the transmission system was run at three torque levels, as well as two mast lifting and two mast bending levels. The test rig was also subjected to disassembly and reassembly of the main pinion housing to simulate the effect of maintenance operations. An analysis of variance based on the total power of the spectral distribution indicates the relative effect of each experimental factor, including Wong interactions with torque. Reinstallation of the main pinion assembly is shown to introduce changes in the vibration signature, suggesting the possibility of a strong effect of maintenance on HUMS design and use. Based on these results, further research will be conducted to compare these vibration responses with actual OH58c helicopter transmission vibration patterns.

Integrated predictive maintenance program vibration and lube oil analysis: Part I - history and the vibration program

International Nuclear Information System (INIS)

Maxwell, H.

1996-01-01

This paper is the first of two papers which describe the Predictive Maintenance Program for rotating machines at the Palo Verde Nuclear Generating Station. The organization has recently been restructured and significant benefits have been realized by the interaction, or open-quotes synergyclose quotes between the Vibration Program and the Lube Oil Analysis Program. This paper starts with the oldest part of the program - the Vibration Program and discusses the evolution of the program to its current state. The open-quotes Vibrationclose quotes view of the combined program is then presented

Instantaneous Purified Orbit: A New Tool for Analysis of Nonstationary Vibration of Rotor System

Directory of Open Access Journals (Sweden)

Shi Dongfeng

2001-01-01

Full Text Available In some circumstances, vibration signals of large rotating machinery possess time-varying characteristics to some extent. Traditional diagnosis methods, such as FFT spectrum and orbit diagram, are confronted with a huge challenge to deal with this problem. This work aims at studying the four intrinsic drawbacks of conventional vibration signal processing method and instantaneous purified orbit (IPO on the basis of improved Fourier spectrum (IFS to analyze nonstationary vibration. On account of integration, the benefits of short period Fourier transform (SPFT and regular holospectrum, this method can intuitively reflect vibration characteristics of’a rotor system by means of parameter analysis for corresponding frequency ellipses. Practical examples, such as transient vibration in run-up stages and bistable condition of rotor show that IPO is a powerful tool for diagnosis and analysis of the vibration behavior of rotor systems.

Emissivity compensated spectral pyrometry—algorithm and sensitivity analysis

International Nuclear Information System (INIS)

Hagqvist, Petter; Sikström, Fredrik; Christiansson, Anna-Karin; Lennartson, Bengt

2014-01-01

In order to solve the problem of non-contact temperature measurements on an object with varying emissivity, a new method is herein described and evaluated. The method uses spectral radiance measurements and converts them to temperature readings. It proves to be resilient towards changes in spectral emissivity and tolerates noisy spectral measurements. It is based on an assumption of smooth changes in emissivity and uses historical values of spectral emissivity and temperature for estimating current spectral emissivity. The algorithm, its constituent steps and accompanying parameters are described and discussed. A thorough sensitivity analysis of the method is carried out through simulations. No rigorous instrument calibration is needed for the presented method and it is therefore industrially tractable. (paper)

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.

Modeling and analysis of circular flexural-vibration-mode piezoelectric transformer.

Science.gov (United States)

Huang, Yihua; Huang, Wei

2010-12-01

We propose a circular flexural-vibration-mode piezoelectric transformer and perform a theoretical analysis of the transformer. An equivalent circuit is derived from the equations of piezoelectricity and the Hamilton's principle. With this equivalent circuit, the voltage gain ratio, input impedance, and the efficiency of the circular flexural-vibration-mode piezoelectric transformer can be determined. The basic behavior of the transformer is shown by numerical results.

Analysis of vibration of exhaust valve pipeline in nuclear power plant

International Nuclear Information System (INIS)

Tan Ping

2005-01-01

Pipeline system for conveying pressurized steam often operates under time-varying conditions due to the valve operations. This may cause vibration problems as a result the pipeline system suffered vibration damage. In this paper, a finite element formulation for the exhaust dynamic equations that include the effect of all pipe supports, and hangers is introduced and applied to the dynamic analysis of the pipeline system used in a nuclear power plant. the vibration response of steam-conveying pipeline induced by valve exhaust has been studied. The model is validated with a fieldwork experimental pipeline system. the mechanical vibrations from steam exhaust valves can be eliminated by careful design of the valve plug and seat. (authors)

An adjoint method of sensitivity analysis for residual vibrations of structures subject to impacts

Science.gov (United States)

Yan, Kun; Cheng, Gengdong

2018-03-01

For structures subject to impact loads, the residual vibration reduction is more and more important as the machines become faster and lighter. An efficient sensitivity analysis of residual vibration with respect to structural or operational parameters is indispensable for using a gradient based optimization algorithm, which reduces the residual vibration in either active or passive way. In this paper, an integrated quadratic performance index is used as the measure of the residual vibration, since it globally measures the residual vibration response and its calculation can be simplified greatly with Lyapunov equation. Several sensitivity analysis approaches for performance index were developed based on the assumption that the initial excitations of residual vibration were given and independent of structural design. Since the resulting excitations by the impact load often depend on structural design, this paper aims to propose a new efficient sensitivity analysis method for residual vibration of structures subject to impacts to consider the dependence. The new method is developed by combining two existing methods and using adjoint variable approach. Three numerical examples are carried out and demonstrate the accuracy of the proposed method. The numerical results show that the dependence of initial excitations on structural design variables may strongly affects the accuracy of sensitivities.

Spectral Envelopes and Additive + Residual Analysis/Synthesis

Science.gov (United States)

Rodet, Xavier; Schwarz, Diemo

The subject of this chapter is the estimation, representation, modification, and use of spectral envelopes in the context of sinusoidal-additive-plus-residual analysis/synthesis. A spectral envelope is an amplitude-vs-frequency function, which may be obtained from the envelope of a short-time spectrum (Rodet et al., 1987; Schwarz, 1998). [Precise definitions of such an envelope and short-time spectrum (STS) are given in Section 2.] The additive-plus-residual analysis/synthesis method is based on a representation of signals in terms of a sum of time-varying sinusoids and of a non-sinusoidal residual signal [e.g., see Serra (1989), Laroche et al. (1993), McAulay and Quatieri (1995), and Ding and Qian (1997)]. Many musical sound signals may be described as a combination of a nearly periodic waveform and colored noise. The nearly periodic part of the signal can be viewed as a sum of sinusoidal components, called partials, with time-varying frequency and amplitude. Such sinusoidal components are easily observed on a spectral analysis display (Fig. 5.1) as obtained, for instance, from a discrete Fourier transform.

Spatio-spectral analysis of ionization times in high-harmonic generation

Energy Technology Data Exchange (ETDEWEB)

Soifer, Hadas, E-mail: hadas.soifer@weizmann.ac.il [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Dagan, Michal; Shafir, Dror; Bruner, Barry D. [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel); Ivanov, Misha Yu. [Department of Physics, Imperial College London, South Kensington Campus, SW7 2AZ London (United Kingdom); Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin (Germany); Serbinenko, Valeria; Barth, Ingo; Smirnova, Olga [Max-Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max-Born-Strasse 2A, D-12489 Berlin (Germany); Dudovich, Nirit [Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100 (Israel)

2013-03-12

Graphical abstract: A spatio-spectral analysis of the two-color oscillation phase allows us to accurately separate short and long trajectories and reconstruct their ionization times. Highlights: ► We perform a complete spatio-spectral analysis of the high harmonic generation process. ► We analyze the ionization times across the entire spatio-spectral plane of the harmonics. ► We apply this analysis to reconstruct the ionization times of both short and long trajectories. - Abstract: Recollision experiments have been very successful in resolving attosecond scale dynamics. However, such schemes rely on the single atom response, neglecting the macroscopic properties of the interaction and the effects of using multi-cycle laser fields. In this paper we perform a complete spatio-spectral analysis of the high harmonic generation process and resolve the distribution of the subcycle dynamics of the recolliding electron. Specifically, we focus on the measurement of ionization times. Recently, we have demonstrated that the addition of a weak, crossed polarized second harmonic field allows us to resolve the moment of ionization (Shafir, 2012) [1]. In this paper we extend this measurement and perform a complete spatio-spectral analysis. We apply this analysis to reconstruct the ionization times of both short and long trajectories showing good agreement with the quantum path analysis.

PIXE-quantified AXSIA: Elemental mapping by multivariate spectral analysis

International Nuclear Information System (INIS)

Doyle, B.L.; Provencio, P.P.; Kotula, P.G.; Antolak, A.J.; Ryan, C.G.; Campbell, J.L.; Barrett, K.

2006-01-01

Automated, nonbiased, multivariate statistical analysis techniques are useful for converting very large amounts of data into a smaller, more manageable number of chemical components (spectra and images) that are needed to describe the measurement. We report the first use of the multivariate spectral analysis program AXSIA (Automated eXpert Spectral Image Analysis) developed at Sandia National Laboratories to quantitatively analyze micro-PIXE data maps. AXSIA implements a multivariate curve resolution technique that reduces the spectral image data sets into a limited number of physically realizable and easily interpretable components (including both spectra and images). We show that the principal component spectra can be further analyzed using conventional PIXE programs to convert the weighting images into quantitative concentration maps. A common elemental data set has been analyzed using three different PIXE analysis codes and the results compared to the cases when each of these codes is used to separately analyze the associated AXSIA principal component spectral data. We find that these comparisons are in good quantitative agreement with each other

Analysis of the Impacts of Bearing on Vibration Characteristics of Rotor

Directory of Open Access Journals (Sweden)

Peiji Yang

2017-01-01

Full Text Available Aiming at a Top Gas Recovery Turbine Unit (TRT with double support rotor and the extending disk end, theoretical and experimental analysis about influence of cylindrical bearing and four-lobe bearing on vibration of TRT rotor system are conducted in this paper. The results indicate that vibration of the rotor supported by cylindrical bearing is more stable than that supported by four-lobe bearing at the driving end (DE and the nondriving end (NDE. The amplitude of rotor is supported by both of these types of bearing increases as the speed increases at the NDE, while the amplitude of the DE remains unchanged. Comparing with the result of theoretical analysis, the practical test results are more consistent with the theoretical response analysis conducted by applying unbalanced mass at the extending disk end. This paper presents an analysis method of the critical characteristics of a double support rotor system with the extending disk end and provides reference value for dealing with vibration fault of double support rotor system with the extending disk end.

A PLL-based resampling technique for vibration analysis in variable-speed wind turbines with PMSG: A bearing fault case

Science.gov (United States)

Pezzani, Carlos M.; Bossio, José M.; Castellino, Ariel M.; Bossio, Guillermo R.; De Angelo, Cristian H.

2017-02-01

Condition monitoring in permanent magnet synchronous machines has gained interest due to the increasing use in applications such as electric traction and power generation. Particularly in wind power generation, non-invasive condition monitoring techniques are of great importance. Usually, in such applications the access to the generator is complex and costly, while unexpected breakdowns results in high repair costs. This paper presents a technique which allows using vibration analysis for bearing fault detection in permanent magnet synchronous generators used in wind turbines. Given that in wind power applications the generator rotational speed may vary during normal operation, it is necessary to use special sampling techniques to apply spectral analysis of mechanical vibrations. In this work, a resampling technique based on order tracking without measuring the rotor position is proposed. To synchronize sampling with rotor position, an estimation of the rotor position obtained from the angle of the voltage vector is proposed. This angle is obtained from a phase-locked loop synchronized with the generator voltages. The proposed strategy is validated by laboratory experimental results obtained from a permanent magnet synchronous generator. Results with single point defects in the outer race of a bearing under variable speed and load conditions are presented.

Quantum chemical studies on structural, vibrational, nonlinear optical properties and chemical reactivity of indigo carmine dye

Science.gov (United States)

El-Mansy, M. A. M.

2017-08-01

Structural and vibrational spectroscopic studies were performed on indigo carmine (IC) isomers using FT-IR spectral analysis along with DFT/B3LYP method utilizing Gaussian 09 software. GaussView 5 program has been employed to perform a detailed interpretation of vibrational spectra. Simulation of infrared spectra has led to an excellent overall agreement with the observed spectral patterns. Mulliken population analyses on atomic charges, MEP, HOMO-LUMO, NLO, first order hyperpolarizability and thermodynamic properties have been examined by (DFT/B3LYP) method with the SDD basis set level. Density of state spectra (DOS) were calculated using GaussSum 3 at the same level of theory. Molecular modeling approved that DOS Spectra are the most significant tools for differentiating between two IC isomers so far. Moreover, The IC isomers (cis-isomer) have shown an extended applicability for manufacturing both NLO and photovoltaic devices such as solar cells.

Vibrational spectra and normal co-ordinate analysis of 2-aminopyridine and 2-amino picoline.

Science.gov (United States)

Jose, Sujin P; Mohan, S

2006-05-01

The Fourier transform infrared (FT-IR) and Raman (FT-R) spectra of 2-aminopyridine and 2-amino picoline were recorded and the observed frequencies were assigned to various modes of vibration in terms of fundamentals by assuming Cs point group symmetry. A normal co-ordinate analysis was also carried out for the proper assignment of the vibrational frequencies using simple valence force field. A complete vibrational analysis is presented here for the molecules and the results are briefly discussed.

Vibration of hydraulic machinery

CERN Document Server

Wu, Yulin; Liu, Shuhong; Dou, Hua-Shu; Qian, Zhongdong

2013-01-01

Vibration of Hydraulic Machinery deals with the vibration problem which has significant influence on the safety and reliable operation of hydraulic machinery. It provides new achievements and the latest developments in these areas, even in the basic areas of this subject. The present book covers the fundamentals of mechanical vibration and rotordynamics as well as their main numerical models and analysis methods for the vibration prediction. The mechanical and hydraulic excitations to the vibration are analyzed, and the pressure fluctuations induced by the unsteady turbulent flow is predicted in order to obtain the unsteady loads. This book also discusses the loads, constraint conditions and the elastic and damping characters of the mechanical system, the structure dynamic analysis, the rotor dynamic analysis and the system instability of hydraulic machines, including the illustration of monitoring system for the instability and the vibration in hydraulic units. All the problems are necessary for vibration pr...

Three-dimensional free vibration analysis of thick laminated circular ...

African Journals Online (AJOL)

Dr Oke

1 ,2 Department of Mechanical Engineering, Maulana Azad National Institute of Technology, Bhopal-462003, INDIA ... In this communication, a numerical analysis regarding free vibration of thick laminated .... ANSYS finite element software.

Probing electronic and vibrational properties at the electrochemical interface using SFG spectroscopy: Methanol electro-oxidation on Pt(1 1 0)

Science.gov (United States)

Vidal, F.; Busson, B.; Tadjeddine, A.

2005-02-01

We report the study of methanol electro-oxidation on Pt(1 1 0) using infrared-visible sum-frequency generation (SFG) vibrational spectroscopy. The use of this technique enables to probe the vibrational and electronic properties of the interface simultaneously in situ. We have investigated the vibrational properties of the interface in the CO ads internal stretch spectral region (1700-2150 cm -1) over a wide range of potentials. The analysis of the evolution of the C-O stretch line shape, which is related to the interference between the vibrational and electronic parts of the non-linear response, with the potential allows us to show that the onset of bulk methanol oxidation corresponds to the transition from a negatively to a positively charged surface.

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.

Torsional vibration analysis in turbo-generator shaft due to mal-synchronization fault

Science.gov (United States)

Bangunde, Abhishek; Kumar, Tarun; Kumar, Rajeev; Jain, S. C.

2018-03-01

A rotor of turbo-generator shafting is many times subjected to torsional vibrations during its lifespan. The reasons behind these vibrations are three-Phase fault, two-phase fault, line to ground fault, faulty-mal synchronization etc. Sometimes these vibrations can cause complete failure of turbo-generator shafting system. To calculate moment variation during these faults on the shafting system vibration analysis is done using Finite Elements Methods to calculate mass and stiffness matrix. The electrical disturbance caused during Mal-synchronization is put on generator section, and corresponding second order equations are solved by using “Duhamel Integral”. From the moment variation plots at four sections critically loaded sections are identified.

Application of pattern recognition techniques to the detection of the Phenix reactor control rods vibrations

International Nuclear Information System (INIS)

Zwingelstein, G.; Deat, M.; Le Guillou, G.

1979-01-01

The incipient detection of control rods vibrations is very important for the safety of the operating plants. This detection can be achieved by an analysis of the peaks of the power spectrum density of the neutron noise. Pattern Recognition techniques were applied to detect the rod vibrations which occured at the fast breeder Phenix (250MWe). In the first part we give a description of the basic pattern which is used to characterize the behavior of the plant. The pattern is considered as column vector in n dimensional Euclidian space where the components are the samples of the power spectral density of the neutron noise. In the second part, a recursive learning procedure of the normal patterns which provides the mean and the variance of the estimates is described. In the third part the classification problem has been framed in terms of a partitioning procedure in n dimensional space which encloses regions corresponding to normal operations. This pattern recognition scheme was applied to the detection of rod vibrations with neutron data collected at the Phenix site before and after occurence of the vibrations. The analysis was carried out with a 42-dimensional measurement space. The learned pattern was estimated with 150 measurement vectors which correspond to the period without vibrations. The efficiency of the surveillance scheme is then demonstrated by processing separately 119 measurement vectors recorded during the rod vibration period

Homogeneity Analysis of a MEMS-based PZT Thick Film Vibration Energy Harvester Manufacturing Process

DEFF Research Database (Denmark)

Lei, Anders; Xu, Ruichao; Borregaard, Louise M.

2012-01-01

This paper presents a homogeneity analysis of a high yield wafer scale fabrication of MEMS-based unimorph silicon/PZT thick film vibration energy harvesters aimed towards vibration sources with peak vibrations in the range of around 300Hz. A wafer with a yield of 91% (41/45 devices) has been...

Vibrational spectroscopic study of terbutaline hemisulphate

Science.gov (United States)

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

2009-05-01

The Raman spectrum of terbutaline hemisulphate is reported for the first time, and molecular assignments are proposed on the basis of ab initio BLYP DFT calculations with a 6-31G* basis set and vibrational frequencies predicted within the quasi-harmonic approximation; these predictions compare favourably with the observed vibrational spectra. Comparison with previously published infrared data explains several spectral features. The results from this study provide data that can be used for the preparative process monitoring of terbutaline hemisulphate, an important β 2 agonist drug in various dosage forms and its interaction with excipients and other components.

Benefits Of Vibration Analysis For Development Of Equipment In HLW Tanks - 12341

International Nuclear Information System (INIS)

Stefanko, D.; Herbert, J.

2012-01-01

Vibration analyses of equipment intended for use in the Savannah River Site (SRS) radioactive liquid waste storage tanks are performed during pre-deployment testing and has been demonstrated to be effective in reducing the life-cycle costs of the equipment. Benefits of using vibration analysis to identify rotating machinery problems prior to deployment in radioactive service will be presented in this paper. Problems encountered at SRS and actions to correct or lessen the severity of the problem are discussed. In short, multi-million dollar cost saving have been realized at SRS as a direct result of vibration analysis on existing equipment. Vibration analysis of equipment prior to installation can potentially reduce inservice failures, and increases reliability. High-level radioactive waste is currently stored in underground carbon steel waste tanks at the United States Department of Energy (DOE) Savannah River Site and at the Hanford Site, WA. Various types of rotating machinery (pumps and separations equipment) are used to manage and retrieve the tank contents. Installation, maintenance, and repair of these pumps and other equipment are expensive. In fact, costs to remove and replace a single pump can be as high as a half million dollars due to requirements for radioactive containment. Problems that lead to in-service maintenance and/or equipment replacement can quickly exceed the initial investment, increase radiological exposure, generate additional waste, and risk contamination of personnel and the work environment. Several different types of equipment are considered in this paper, but pumps provide an initial example for the use of vibration analysis. Long-shaft (45 foot long) and short-shaft (5-10 feet long) equipment arrangements are used for 25-350 horsepower slurry mixing and transfer pumps in the SRS HLW tanks. Each pump has a unique design, operating characteristics and associated costs, sometimes exceeding a million dollars. Vibration data are routinely

BENEFITS OF VIBRATION ANALYSIS FOR DEVELOPMENT OF EQUIPMENT IN HLW TANKS - 12341

Energy Technology Data Exchange (ETDEWEB)

Stefanko, D.; Herbert, J.

2012-01-10

Vibration analyses of equipment intended for use in the Savannah River Site (SRS) radioactive liquid waste storage tanks are performed during pre-deployment testing and has been demonstrated to be effective in reducing the life-cycle costs of the equipment. Benefits of using vibration analysis to identify rotating machinery problems prior to deployment in radioactive service will be presented in this paper. Problems encountered at SRS and actions to correct or lessen the severity of the problem are discussed. In short, multi-million dollar cost saving have been realized at SRS as a direct result of vibration analysis on existing equipment. Vibration analysis of equipment prior to installation can potentially reduce inservice failures, and increases reliability. High-level radioactive waste is currently stored in underground carbon steel waste tanks at the United States Department of Energy (DOE) Savannah River Site and at the Hanford Site, WA. Various types of rotating machinery (pumps and separations equipment) are used to manage and retrieve the tank contents. Installation, maintenance, and repair of these pumps and other equipment are expensive. In fact, costs to remove and replace a single pump can be as high as a half million dollars due to requirements for radioactive containment. Problems that lead to in-service maintenance and/or equipment replacement can quickly exceed the initial investment, increase radiological exposure, generate additional waste, and risk contamination of personnel and the work environment. Several different types of equipment are considered in this paper, but pumps provide an initial example for the use of vibration analysis. Long-shaft (45 foot long) and short-shaft (5-10 feet long) equipment arrangements are used for 25-350 horsepower slurry mixing and transfer pumps in the SRS HLW tanks. Each pump has a unique design, operating characteristics and associated costs, sometimes exceeding a million dollars. Vibration data are routinely

One stacked-column vibration test and analysis for VHTR core

International Nuclear Information System (INIS)

Ikushima, Takeshi; Ishizuka, Hiroshi; Ide, Akira; Hayakawa, Hitoshi; Shingai, Kazuteru.

1978-07-01

This paper describes experimental results of the vibration test on a single stacked-column and compares them with the analytical results. A 1/2 scale model of the core element of a very high temperature gas-cooled reactor (VHTR) was set on a shaking table. Sinusoidal waves, response time history waves, beat wave and step wave of input acceleration 100 - 900 gal in the frequency of 0.5 to 15 Hz were used to vibrate the table horizontally. Results are as follows: (1) The column has a non-linear resonance and exhibits a hysteresis response with jump points. (2) The column vibration characteristics is similar to that of the finite beams connected with non-linear soft spring. (3) The column resonance frequency decreases with increasing input acceleration. (4) The impact force increases with increasing input acceleration and boundary gap width. (5) Good correlation in vibration behavior of the stacked-column and impact force on the boundary between test and analysis was obtained. (auth.)

Spectral signature verification using statistical analysis and text mining

Science.gov (United States)

DeCoster, Mallory E.; Firpi, Alexe H.; Jacobs, Samantha K.; Cone, Shelli R.; Tzeng, Nigel H.; Rodriguez, Benjamin M.

2016-05-01

In the spectral science community, numerous spectral signatures are stored in databases representative of many sample materials collected from a variety of spectrometers and spectroscopists. Due to the variety and variability of the spectra that comprise many spectral databases, it is necessary to establish a metric for validating the quality of spectral signatures. This has been an area of great discussion and debate in the spectral science community. This paper discusses a method that independently validates two different aspects of a spectral signature to arrive at a final qualitative assessment; the textual meta-data and numerical spectral data. Results associated with the spectral data stored in the Signature Database1 (SigDB) are proposed. The numerical data comprising a sample material's spectrum is validated based on statistical properties derived from an ideal population set. The quality of the test spectrum is ranked based on a spectral angle mapper (SAM) comparison to the mean spectrum derived from the population set. Additionally, the contextual data of a test spectrum is qualitatively analyzed using lexical analysis text mining. This technique analyzes to understand the syntax of the meta-data to provide local learning patterns and trends within the spectral data, indicative of the test spectrum's quality. Text mining applications have successfully been implemented for security2 (text encryption/decryption), biomedical3 , and marketing4 applications. The text mining lexical analysis algorithm is trained on the meta-data patterns of a subset of high and low quality spectra, in order to have a model to apply to the entire SigDB data set. The statistical and textual methods combine to assess the quality of a test spectrum existing in a database without the need of an expert user. This method has been compared to other validation methods accepted by the spectral science community, and has provided promising results when a baseline spectral signature is

Vibration analysis of continuous maglev guideways with a moving distributed load model

International Nuclear Information System (INIS)

Teng, N G; Qiao, B P

2008-01-01

A model of moving distributed load with a constant speed is established for vertical vibration analysis of a continuous guideway in maglev transportation system. The guideway is considered as a continuous structural system and the action of maglev vehicles on guideways is considered as a moving distributed load. Vibration of the continuous guideways used in Shanghai maglev line is analyzed with this model. The factors that affect the vibration of the guideways, such as speeds, guideway's spans, frequency and damping, are discussed

Measurement and analysis of vibrational behavior of an SNR-fuel element in sodium flow

International Nuclear Information System (INIS)

Hess, B.F.H.; Ruppert, E.; Schmidt, H.; Vinzens, K.

1975-01-01

Within the framework of SNR-300 fuel element development programme a complete full size fuel element dummy has been tested thoroughly for nearly 3000 hours at 650 deg C system temperature in the AKB sodium loop at Interatom, Bensberg. It is known that the coolant flow through a subassembly can induce flutter or vibrations of structural parts such as single pins, the wrapper and the total pin bundle all of which have been of interest during this test. To detect these vibrations of different structural parts simultaneously with a minimum of instrumentation only 3 weldable high temperature strain gauges were employed. These strain gauges were especially prepared and bent in such a way as to form a bridge between the inner wrapper and a fuel pin top and spot-welded to both the wrapper and the fuel pin. Although this arrangement seems to be a rather unusual one, the simultaneous-measurement of bundle, wrapper and pin vibrations was possible and periodic flow fluctuations were also detected. The presented results are only relative due to calibration difficulties with these deformed strain gauges which were first used during this test. It is, however, believed that this arrangement, in connection with the proposed anlytical approach, leads to a simple and technical representation of the vibrational behavior of core elements during sodium tests. Detailed information needed for check and calibration of computer codes are however displayed by the respective power spectral density functions

A novel vibration-based fault diagnostic algorithm for gearboxes under speed fluctuations without rotational speed measurement

Science.gov (United States)

Hong, Liu; Qu, Yongzhi; Dhupia, Jaspreet Singh; Sheng, Shuangwen; Tan, Yuegang; Zhou, Zude

2017-09-01

The localized failures of gears introduce cyclic-transient impulses in the measured gearbox vibration signals. These impulses are usually identified from the sidebands around gear-mesh harmonics through the spectral analysis of cyclo-stationary signals. However, in practice, several high-powered applications of gearboxes like wind turbines are intrinsically characterized by nonstationary processes that blur the measured vibration spectra of a gearbox and deteriorate the efficacy of spectral diagnostic methods. Although order-tracking techniques have been proposed to improve the performance of spectral diagnosis for nonstationary signals measured in such applications, the required hardware for the measurement of rotational speed of these machines is often unavailable in industrial settings. Moreover, existing tacho-less order-tracking approaches are usually limited by the high time-frequency resolution requirement, which is a prerequisite for the precise estimation of the instantaneous frequency. To address such issues, a novel fault-signature enhancement algorithm is proposed that can alleviate the spectral smearing without the need of rotational speed measurement. This proposed tacho-less diagnostic technique resamples the measured acceleration signal of the gearbox based on the optimal warping path evaluated from the fast dynamic time-warping algorithm, which aligns a filtered shaft rotational harmonic signal with respect to a reference signal assuming a constant shaft rotational speed estimated from the approximation of operational speed. The effectiveness of this method is validated using both simulated signals from a fixed-axis gear pair under nonstationary conditions and experimental measurements from a 750-kW planetary wind turbine gearbox on a dynamometer test rig. The results demonstrate that the proposed algorithm can identify fault information from typical gearbox vibration measurements carried out in a resource-constrained industrial environment.

Analysis of flow induced vibration in heat exchangers

International Nuclear Information System (INIS)

Beek, A.W. van

1977-01-01

A description will be given of three different types of heat exchangers developed by the Dutch Nuclear Industry Group ''Neratoom'' in cooperation with TNO for the sodium-cooled fast breeder reactor SNR-300 at Kalkar. Moreover, the research related with flow induced vibrations carried out by TNO (Organization for Applied Scientific Research) will be presented. The flow induced forces on the tubes of the straight-tube steam generators were measured at the inlet and outlet section where partial crossflow occurs. With the measured flow induced forces the response of a tube was calculated as a function of the tube-to-supportbush clearances taking into account the non-linear damping effects from the sodium. The theoretical results showed that for this particular design no tube impact damage is to be expected which was confirmed later by a full scale experiment. Special attention will be devoted to the steam generator with helical-coil tube-bundles, where the sodium flows in a counter cross-flow over the tube-bundle. Extensive measurements of the power spectra of the flow induced forces were carried out since no information could be found in the literature. The vibration analysis will be presented and vibration modes of the entire bundle will be compared with experimentally obtained results. Finally a description of the vibration tests to be carried out on the intermediate heat exchanger (IHX) will be presented. (author)

Analysis of flow induced vibration in heat exchangers

Energy Technology Data Exchange (ETDEWEB)

Beek, A.W. van [Institute for Mechanical Constructions TNO, Delft (Netherlands)

1977-12-01

A description will be given of three different types of heat exchangers developed by the Dutch Nuclear Industry Group ''Neratoom'' in cooperation with TNO for the sodium-cooled fast breeder reactor SNR-300 at Kalkar. Moreover, the research related with flow induced vibrations carried out by TNO (Organization for Applied Scientific Research) will be presented. The flow induced forces on the tubes of the straight-tube steam generators were measured at the inlet and outlet section where partial crossflow occurs. With the measured flow induced forces the response of a tube was calculated as a function of the tube-to-supportbush clearances taking into account the non-linear damping effects from the sodium. The theoretical results showed that for this particular design no tube impact damage is to be expected which was confirmed later by a full scale experiment. Special attention will be devoted to the steam generator with helical-coil tube-bundles, where the sodium flows in a counter cross-flow over the tube-bundle. Extensive measurements of the power spectra of the flow induced forces were carried out since no information could be found in the literature. The vibration analysis will be presented and vibration modes of the entire bundle will be compared with experimentally obtained results. Finally a description of the vibration tests to be carried out on the intermediate heat exchanger (IHX) will be presented. (author)

Localized Surface Plasmons in Vibrating Graphene Nanodisks

DEFF Research Database (Denmark)

Wang, Weihua; Li, Bo-Hong; Stassen, Erik

2016-01-01

in graphene disks have the additional benefit to be highly tunable via electrical stimulation. Mechanical vibrations create structural deformations in ways where the excitation of localized surface plasmons can be strongly modulated. We show that the spectral shift in such a scenario is determined...... by a complex interplay between the symmetry and shape of the modal vibrations and the plasmonic mode pattern. Tuning confined modes of light in graphene via acoustic excitations, paves new avenues in shaping the sensitivity of plasmonic detectors, and in the enhancement of the interaction with optical emitters...

Detector point of view of reactor internal vibrations under Gaussian coloured random forces - the problem of fitting neutron noise experimental data

International Nuclear Information System (INIS)

Arnal, R.S.; Martin, G.V.; Gonzalez, J.L.M.-C.

1988-01-01

This paper studies the local vibrations of reactor components driven by Gaussian coloured and white forces, when nonlinear vibrations arise. We study also the important problem of noise sources, modelization and the noise propagation through the neutron field using the discrete ordinates transport theory. Finally, we study the effect of the neutron field upon the PSD (power spectral density) of the noise source and we analyse the problem of fitting neutron noise experimental data to perform pattern recognition analysis. (author)

A study of vibrational relaxation of electronically-excited molecules

International Nuclear Information System (INIS)

Datsyuk, V.V.; Izmailov, I.A.; Kochelap, V.A.

1992-09-01

The time kinetics of the vibrational relaxation of excimers is studied in the diffusional approximation. Simple formulae for functions of nonstationary vibrational distribution are found for the electronically excited molecules. Some spectral-kinetic dependencies of the excimer luminescence are explained in a new way. The possibilities of the determination of excimer parameters are discussed. The dependence of energetical characteristics of excimer lasers on these parameters is particularly emphasized. (author). 22 refs, 5 figs

Vibration analysis of continuous maglev guideways with a moving distributed load model

Energy Technology Data Exchange (ETDEWEB)

Teng, N G; Qiao, B P [Department of Civil Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240 (China)

2008-02-15

A model of moving distributed load with a constant speed is established for vertical vibration analysis of a continuous guideway in maglev transportation system. The guideway is considered as a continuous structural system and the action of maglev vehicles on guideways is considered as a moving distributed load. Vibration of the continuous guideways used in Shanghai maglev line is analyzed with this model. The factors that affect the vibration of the guideways, such as speeds, guideway's spans, frequency and damping, are discussed.

Spectral Analysis of Moderately Charged Rare-Gas Atoms

Directory of Open Access Journals (Sweden)

Jorge Reyna Almandos

2017-03-01

Full Text Available This article presents a review concerning the spectral analysis of several ions of neon, argon, krypton and xenon, with impact on laser studies and astrophysics that were mainly carried out in our collaborative groups between Argentina and Brazil during many years. The spectra were recorded from the vacuum ultraviolet to infrared regions using pulsed discharges. Semi-empirical approaches with relativistic Hartree–Fock and Dirac-Fock calculations were also included in these investigations. The spectral analysis produced new classified lines and energy levels. Lifetimes and oscillator strengths were also calculated.

Evaluation of Fourier integral. Spectral analysis of seismic events

International Nuclear Information System (INIS)

Chitaru, Cristian; Enescu, Dumitru

2003-01-01

Spectral analysis of seismic events represents a method for great earthquake prediction. The seismic signal is not a sinusoidal signal; for this, it is necessary to find a method for best approximation of real signal with a sinusoidal signal. The 'Quanterra' broadband station allows the data access in numerical and/or graphical forms. With the numerical form we can easily make a computer program (MSOFFICE-EXCEL) for spectral analysis. (authors)

Coupled Boundary and Finite Element Analysis of Vibration from Railway Tunnels

DEFF Research Database (Denmark)

Andersen, Lars; Jones, C.J.C.

2006-01-01

The analysis of vibration from railway tunnels is of growing interest as new and higher-speed railways are built under the ground to address the transport problems of growing modern urban areas around cities. Such analysis can be carried out using numerical methods but models and therefore comput...... body vibration (about 4 to 80 Hz). A coupled finite element and boundary element scheme is applied in both two and three dimensions. Two tunnel designs are considered: a cut-and-cover tunnel for a double track and a single-track tunnel dug with the New Austrian Tunnelling Method (NATM)....

Vibrational spectroscopy (FT-IR and Laser-Raman) investigation, and computational (M06-2X and B3LYP) analysis on the structure of 4-(3-fluorophenyl)-1-(propan-2-ylidene)-thiosemicarbazone.

Science.gov (United States)

Sert, Yusuf; Miroslaw, Barbara; Çırak, Çağrı; Doğan, Hatice; Szulczyk, Daniel; Struga, Marta

2014-07-15

In this study, the experimental and theoretical vibrational spectral analysis of 4-(3-fluorophenyl)-1-(propan-2-ylidene)-thiosemicarbazone have been carried out. The experimental FT-IR (4000-400 cm(-1)) and Laser-Raman spectra (4000-100 cm(-1)) have been recorded for the solid state samples. The theoretical vibrational frequencies and the optimized geometric parameters (bond lengths and angles) have been calculated for gas phase using density functional theory (DFT/B3LYP: Becke, 3-parameter, Lee-Yang-Parr) and M06-2X (the highly parametrized, empirical exchange correlation function) quantum chemical methods with 6-311++G(d,p) basis set. The diversity in molecular geometry of fluorophenyl substituted thiosemicarbazones has been discussed based on the X-ray crystal structure reports and theoretical calculation results from the literature. The assignments of the vibrational frequencies have been done on the basis of potential energy distribution (PED) analysis by using VEDA4 software. A good correlation was found between the computed and experimental geometric and vibrational data. In addition, the highest occupied (HOMO) and lowest unoccupied (LUMO) molecular orbital energy levels and other related molecular energy values of the compound have been determined using the same level of theoretical calculations. Copyright © 2014 Elsevier B.V. All rights reserved.

Bridge Diagnosis by Using Nonlinear Independent Component Analysis and Displacement Analysis

Science.gov (United States)

Zheng, Juanqing; Yeh, Yichun; Ogai, Harutoshi

A daily diagnosis system for bridge monitoring and maintenance is developed based on wireless sensors, signal processing, structure analysis, and displacement analysis. The vibration acceleration data of a bridge are firstly collected through the wireless sensor network by exerting. Nonlinear independent component analysis (ICA) and spectral analysis are used to extract the vibration frequencies of the bridge. After that, through a band pass filter and Simpson's rule the vibration displacement is calculated and the vibration model is obtained to diagnose the bridge. Since linear ICA algorithms work efficiently only in linear mixing environments, a nonlinear ICA model, which is more complicated, is more practical for bridge diagnosis systems. In this paper, we firstly use the post nonlinear method to change the signal data, after that perform linear separation by FastICA, and calculate the vibration displacement of the bridge. The processed data can be used to understand phenomena like corrosion and crack, and evaluate the health condition of the bridge. We apply this system to Nakajima Bridge in Yahata, Kitakyushu, Japan.

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.

Detection of gear cracks in a complex gearbox of wind turbines using supervised bounded component analysis of vibration signals collected from multi-channel sensors

Science.gov (United States)

Li, Zhixiong; Yan, Xinping; Wang, Xuping; Peng, Zhongxiao

2016-06-01

In the complex gear transmission systems, in wind turbines a crack is one of the most common failure modes and can be fatal to the wind turbine power systems. A single sensor may suffer with issues relating to its installation position and direction, resulting in the collection of weak dynamic responses of the cracked gear. A multi-channel sensor system is hence applied in the signal acquisition and the blind source separation (BSS) technologies are employed to optimally process the information collected from multiple sensors. However, literature review finds that most of the BSS based fault detectors did not address the dependence/correlation between different moving components in the gear systems; particularly, the popular used independent component analysis (ICA) assumes mutual independence of different vibration sources. The fault detection performance may be significantly influenced by the dependence/correlation between vibration sources. In order to address this issue, this paper presents a new method based on the supervised order tracking bounded component analysis (SOTBCA) for gear crack detection in wind turbines. The bounded component analysis (BCA) is a state of art technology for dependent source separation and is applied limitedly to communication signals. To make it applicable for vibration analysis, in this work, the order tracking has been appropriately incorporated into the BCA framework to eliminate the noise and disturbance signal components. Then an autoregressive (AR) model built with prior knowledge about the crack fault is employed to supervise the reconstruction of the crack vibration source signature. The SOTBCA only outputs one source signal that has the closest distance with the AR model. Owing to the dependence tolerance ability of the BCA framework, interfering vibration sources that are dependent/correlated with the crack vibration source could be recognized by the SOTBCA, and hence, only useful fault information could be preserved in

Impact Analysis of Roller System Stability for Four-High Mill Horizontal Vibration

Directory of Open Access Journals (Sweden)

Xiao-bin Fan

2016-01-01

Full Text Available In order to study the hot Compact Strip Production (CSP, four-high mill vibration characteristics, and vibration suppression method, the roller system structure stability was analyzed and calculated at first in the paper. And then, the mill stand gap was measured at field and its influence on roll transverse vibration was analyzed. The drum gear coupling effect on the roller system stability and the automatic balance conditions of the coupling transmission torque were studied; the influence of axial force caused by the roller cross on the system stability was analyzed. Finally, the roller transverse friction chatter vibration mechanics model was established; the simulation analysis was carried out with eliminating mill house-bearing clearance and adding floating support for coupling, respectively. And the characteristics of the roller “jump vibration” were studied. We applied copper gaskets to eliminate or reduce mill house-bearing clearance for suppressing the rolling mill vibration on the spot; the test results show that the roller transverse vibration was suppressed after eliminating clearance.

A study on waviness induced vibration of ball bearings based on signal coherence theory

Science.gov (United States)

Liu, Wentao; Zhang, Yun; Feng, Zhi-Jing; Zhao, Jing-Shan; Wang, Dongfeng

2014-11-01

This paper focuses on the effects of waviness on vibration of ball bearings. An experimental analysis method is developed by adopting signal coherence theory of multiple-inputs/single-output (MISO) system. The inputs are waviness excitations of the inner and outer races, and the output is vibration response of the outer ring. Waviness excitation signals are first derived from the manufacturing deviations, and found to be strongly coherent in low frequency range. Virtual input signals are then introduced by the method of orthogonalization. In both cases of vibration acceleration and speed responses, the cumulated virtual input-output coherence function verifies that the first peak region of vibration spectrum is mainly induced by the waviness excitations. In order to distinguish the contributions of the inner and outer races, coherence functions of the virtual inputs with real inputs are calculated, and the results indicate that the outer race waviness contributes more to vibration than the inner race waviness does in the example. Further, a multi-body dynamic model is constructed and employed to frequency response analyses. It is discovered that the waviness induced spectral peak frequency is close to the natural frequency of bearing.

Structural determination of some uranyl compounds by vibrational spectroscopy

International Nuclear Information System (INIS)

Rodriguez S, A.; Martinez Q, E.

1990-07-01

The vibrational spectra of different uranyl compounds has been studied and of it spectral information has been used the fundamental asymmetric vibrational frequency, to determine the length and constant bond force U=O by means of the combination of the concept of absorbed energy and the mathematical expression of Badger modified by Jones. It is intended a factor that simplifies the mathematical treatment and the results are compared with the values obtained for other methods. (Author)

Vibration modes of 3n-gaskets and other fractals

Energy Technology Data Exchange (ETDEWEB)

Bajorin, N; Chen, T; Dagan, A; Emmons, C; Hussein, M; Khalil, M; Mody, P; Steinhurst, B; Teplyaev, A [Department of Mathematics, University of Connecticut, Storrs CT 06269 (United States)

2008-01-11

We rigorously study eigenvalues and eigenfunctions (vibration modes) on the class of self-similar symmetric finitely ramified fractals, which include the Sierpinski gasket and other 3n-gaskets. We consider the classical Laplacian on fractals which generalizes the usual one-dimensional second derivative, is the generator of the self-similar diffusion process, and has possible applications as the quantum Hamiltonian. We develop a theoretical matrix analysis, including analysis of singularities, which allows us to compute eigenvalues, eigenfunctions and their multiplicities exactly. We support our theoretical analysis by symbolic and numerical computations. Our analysis, in particular, allows the computation of the spectral zeta function on fractals and the limiting distribution of eigenvalues (i.e., integrated density of states). We consider such examples as the level-3 Sierpinski gasket, a fractal 3-tree, and the diamond fractal.

MIR and FIR Analysis of Inorganic Species in a Single Data Acquisition

Science.gov (United States)

Wang, Peng; Shilov, Sergey

2017-06-01

The extension of the mid IR towards the far IR spectral range below 400 \\wn is of great interest for molecular vibrational analysis for inorganic and organometallic chemistry, for geological, pharmaceutical, and physical applications, polymorph screening and crystallinity analysis as well as for matrix isolation spectroscopy. In these cases, the additional far infrared region offers insight to low energy vibrations which are observable only there. This includes inorganic species, lattice vibrations or intermolecular vibrations in the ordered solid state. The spectral range of a FTIR spectrometer is defined by the major optical components such as the source, beamsplitter, and detector. The globar source covers a broad spectral range from 8000 to 20 \\wn. However a bottle neck exists with respect to the beamsplitter and detector. To extend the spectral range further into the far IR and THz spectral ranges, one or more additional far IR beam splitters and detectors have been previously required. Two new optic components have been incorporated in a spectrometer to achieve coverage of both the mid and far infrared in a single scan: a wide range MIR-FIR beam splitter and the wide range DLaTGS detector that utilizes a diamond window. The use of a standard SiC IR source with these components yields a spectral range of 6000 down to 50 \\wn in one step for all types of transmittance, reflectance and ATR measurements. Utilizing the external water cooled mercury arc high power lamp the spectral range can be ultimately extended down to 10 \\wn. Examples of application will include emission in MIR-THz range, identification of pigments, additives in polymers, and polymorphism studies.

Piezoelectric energy harvesting from broadband random vibrations

International Nuclear Information System (INIS)

Adhikari, S; Friswell, M I; Inman, D J

2009-01-01

Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples

Piezoelectric energy harvesting from broadband random vibrations

Science.gov (United States)

Adhikari, S.; Friswell, M. I.; Inman, D. J.

2009-11-01

Energy harvesting for the purpose of powering low power electronic sensor systems has received explosive attention in the last few years. Most works using deterministic approaches focusing on using the piezoelectric effect to harvest ambient vibration energy have concentrated on cantilever beams at resonance using harmonic excitation. Here, using a stochastic approach, we focus on using a stack configuration and harvesting broadband vibration energy, a more practically available ambient source. It is assumed that the ambient base excitation is stationary Gaussian white noise, which has a constant power-spectral density across the frequency range considered. The mean power acquired from a piezoelectric vibration-based energy harvester subjected to random base excitation is derived using the theory of random vibrations. Two cases, namely the harvesting circuit with and without an inductor, have been considered. Exact closed-form expressions involving non-dimensional parameters of the electromechanical system have been given and illustrated using numerical examples.

Vulnerability Assessment for a Complex Structure Using Vibration Response Induced by Impact Load

International Nuclear Information System (INIS)

Park, Jeongwon; Park, Junhong; Koo, Man Hoi

2014-01-01

This work presents a vulnerability assessment procedure for a complex structure using vibration characteristics. The structural behavior of a three-dimensional framed structure subjected to impact forces was predicted using the spectral element method. The Timoshenko beam function was applied to simulate the impact wave propagations induced by a high-velocity projectile at relatively high frequencies. The interactions at the joints were analyzed for both flexural and longitudinal wave propagations. Simulations of the impact energy transfer through the entire structure were performed using the transient displacement and acceleration responses obtained from the frequency analysis. The kill probabilities of the crucial components for an operating system were calculated as a function of the predicted acceleration amplitudes according to the acceptable vibration levels. Following the proposed vulnerability assessment procedure, the vulnerable positions of a three-dimensional combat vehicle with high possibilities of damage generation of components by impact loading were identified from the estimated vibration responses

Raman spectral properties of squamous cell carcinoma of oral tissues and cells

Science.gov (United States)

Su, L.; Sun, Y. F.; Chen, Y.; Chen, P.; Shen, A. G.; Wang, X. H.; Jia, J.; Zhao, Y. F.; Zhou, X. D.; Hu, J. M.

2012-01-01

Early diagnosis is the key of the improved survival rates of oral cancer. Raman spectroscopy is sensitive to the early changes of molecular composition and structure that occur in benign lesion during carcinogenesis. In this study, in situ Raman analysis provided distinct spectra that can be used to discriminate between normal and malignant tissues, as well as normal and cancer cells. The biochemical variations between different groups were analyzed by the characteristic bands by comparing the normalized mean spectra. Spectral profiles of normal, malignant conditions show pronounced differences between one another, and multiple Raman markers associated with DNA and protein vibrational modes have been identified that exhibit excellent discrimination power for cancer sample identification. Statistical analyses of the Raman data and classification using principal component analysis (PCA) are shown to be effective for the Raman spectral diagnosis of oral mucosal diseases. The results indicate that the biomolecular differences between normal and malignant conditions are more obviously at the cellular level. This technique could provide a research foundation for the Raman spectral diagnosis of oral mucosal diseases.

Application of microtremor horizontal-to-vertical spectral ratio (MHVSR) analysis for site characterization: State of the art

Science.gov (United States)

Molnar, S.; Cassidy, J. F.; Castellaro, S.; Cornou, C.; Crow, H.; Hunter, J. A.; Matsushima, S.; Sanchez-Sesma, F. J.; Yong, Alan

2018-01-01

Nakamura (Q Rep Railway Tech Res Inst 30:25–33, 1989) popularized the application of the horizontal-to-vertical spectral ratio (HVSR) analysis of microtremor (seismic noise or ambient vibration) recordings to estimate the predominant frequency and amplification factor of earthquake shaking. During the following quarter century, popularity in the microtremor HVSR (MHVSR) method grew; studies have verified the stability of a site’s MHVSR response over time and validated the MHVSR response with that of earthquake HVSR response. Today, MHVSR analysis is a popular reconnaissance tool used worldwide for seismic microzonation and earthquake site characterization in numerous regions, specifically, in the mapping of site period or fundamental frequency and inverted for shear-wave velocity depth profiles, respectively. However, the ubiquity of MHVSR analysis is predominantly a consequence of its ease in application rather than our full understanding of its theory. We present the state of the art in MHVSR analyses in terms of the development of its theoretical basis, current state of practice, and we comment on its future for applications in earthquake site characterization.

Application of Microtremor Horizontal-to-Vertical Spectral Ratio (MHVSR) Analysis for Site Characterization: State of the Art

Science.gov (United States)

Molnar, S.; Cassidy, J. F.; Castellaro, S.; Cornou, C.; Crow, H.; Hunter, J. A.; Matsushima, S.; Sánchez-Sesma, F. J.; Yong, A.

2018-03-01

Nakamura (Q Rep Railway Tech Res Inst 30:25-33, 1989) popularized the application of the horizontal-to-vertical spectral ratio (HVSR) analysis of microtremor (seismic noise or ambient vibration) recordings to estimate the predominant frequency and amplification factor of earthquake shaking. During the following quarter century, popularity in the microtremor HVSR (MHVSR) method grew; studies have verified the stability of a site's MHVSR response over time and validated the MHVSR response with that of earthquake HVSR response. Today, MHVSR analysis is a popular reconnaissance tool used worldwide for seismic microzonation and earthquake site characterization in numerous regions, specifically, in the mapping of site period or fundamental frequency and inverted for shear-wave velocity depth profiles, respectively. However, the ubiquity of MHVSR analysis is predominantly a consequence of its ease in application rather than our full understanding of its theory. We present the state of the art in MHVSR analyses in terms of the development of its theoretical basis, current state of practice, and we comment on its future for applications in earthquake site characterization.

Micro-vibration response of a stochastically excited sandwich beam with a magnetorheological elastomer core and mass

International Nuclear Information System (INIS)

Ying, Z G; Ni, Y Q

2009-01-01

Magnetorheological (MR) elastomers are used to construct a smart sandwich beam for micro-vibration control. The micro-vibration response of a clamped–free sandwich beam with an MR elastomer core and a supplemental mass under stochastic support micro-motion excitation is studied. The dynamic behavior of MR elastomer as a smart viscoelastic material is described by a complex modulus which is controllable by external magnetic field. The sixth-order partial differential equation of motion of the sandwich beam is derived from the dynamic equilibrium, constitutive and geometric relations. A frequency-domain solution method for the stochastic micro-vibration response of the sandwich beam is developed by using the frequency-response function, power spectral density function and spatial eigensolution. The root-mean-square velocity response in terms of the one-third octave frequency band is calculated, and then the response reduction capacity through optimizing the complex modulus of the core is analyzed. Numerical results illustrate the influences of the MR elastomer core parameters on the root-mean-square velocity response and the high response reduction capacity of the sandwich beam. The developed analysis method is applicable to sandwich beams with arbitrary cores described by complex shear moduli under arbitrary stochastic excitations described by power spectral density functions

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.

Distribution of hydrothermally altered rocks in the Reko Diq, Pakistan mineralized area based on spectral analysis of ASTER data

Science.gov (United States)

Rowan, L.C.; Schmidt, R.G.; Mars, J.C.

2006-01-01

The Reko Diq, Pakistan mineralized study area, approximately 10??km in diameter, is underlain by a central zone of hydrothermally altered rocks associated with Cu-Au mineralization. The surrounding country rocks are a variable mixture of unaltered volcanic rocks, fluvial deposits, and eolian quartz sand. Analysis of 15-band Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data of the study area, aided by laboratory spectral reflectance and spectral emittance measurements of field samples, shows that phyllically altered rocks are laterally extensive, and contain localized areas of argillically altered rocks. In the visible through shortwave-infrared (VNIR + SWIR) phyllically altered rocks are characterized by Al-OH absorption in ASTER band 6 because of molecular vibrations in muscovite, whereas argillically altered rocks have an absorption feature in band 5 resulting from alunite. Propylitically altered rocks form a peripheral zone and are present in scattered exposures within the main altered area. Chlorite and muscovite cause distinctive absorption features at 2.33 and 2.20????m, respectively, although less intense 2.33????m absorption is also present in image spectra of country rocks. Important complementary lithologic information was derived by analysis of the spectral emittance data in the 5 thermal-infrared (TIR) bands. Silicified rocks were not distinguished in the 9 VNIR + SWIR bands because of the lack of diagnostic spectral absorption features in quartz in this wavelength region. Quartz-bearing surficial deposits, as well as hydrothermally silicified rocks, were mapped in the TIR bands by using a band 13/band 12 ratio image, which is sensitive to the intensity of the quartz reststrahlen feature. Improved distinction between the quartzose surficial deposits and silicified bedrock was achieved by using matched-filter processing with TIR image spectra for reference. ?? 2006 Elsevier Inc. All rights reserved.

Production of a Beam of Highly Vibrationally Excited CO Using Perturbations

Science.gov (United States)

Bartels, N.; Schäfer, T.; Hühnert, J.; Wodtke, A. M.; Field, R. W.

2012-06-01

For many experimentalists (especially those, who are not spectroscopists), molecular pertubations are a curse, as they make assignments and analysis of spectral data more difficult. Nevertheless, they can also be a boon! In this talk we will show how a molecular beam of CO in high vibrational states (v=17,18) can be prepared by an optical pumping scheme that we call PUMP-PUMP-PERTURB and DUMP (P^3D). P^3D exploits the loaning, via spin-orbit perturbations, of the large oscillator strength of the 4th positive system, A ^1 π ← X ^1 Σ ^+, to the triplet manifold. This allows some nominally spin-forbidden transitions to be exploited in multistep optical pumping schemes. The ability to {state-selectively} prepare CO in high vibrational states opens up new opportunities for molecular beam scattering experiments.

Simultaneous measurements of disk vibration and pressure fluctuation in turbulent flow developing in a model hard disk drive

Energy Technology Data Exchange (ETDEWEB)

Kurashima, D.; Naka, Y.; Fukagata, K. [Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Obi, S., E-mail: obsn@mech.keio.ac.jp [Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)

2011-06-15

The complex flow features inside hard disk drive models are investigated in an axisymmetric and a semi-open shroud configurations. For the axisymmetric case, we have employed both experimental and computational approaches. The experiment focuses on both flow dynamics and the disk vibration, where measurements of the fluctuating pressure and velocity are undertaken at some representative points. The correlation between the disk vibration and the fluctuating pressure in the turbulent flow between disks is evident from the spectral analysis. The experimentally observed fluctuating pressure and velocity are partly due to the disk vibration and its contribution could be estimated by comparing the experiment with the results of a large eddy simulation. For the semi-open shroud case, although the characteristic peaks attributable to the large-scale vortical structure are still observed in the power spectra, the pressure fluctuation and the disk vibration are suppressed when the arm is inserted.

Vibrational analysis of Fourier transform spectrum of the B 3− u (0

Indian Academy of Sciences (India)

... microwave, was recorded on BOMEM DA8 Fourier transform spectrometer at an apodized resolution of 0.035 cm-1. Vibrational constants were improved by putting the wave number of band origins in Deslandre table. The vibrational analysis was supported by determining the Franck–Condon factor and -centroid values.

Thimble vibration analysis and monitoring on 1300 and 900 MW reactors using accelerometers and in core neutron noise

International Nuclear Information System (INIS)

Trenty, A.; Puyal, C.; Vincent, C.; Baeyens, R.; Messainguiral-Bruynooghe, C.; Lagarde, G.

1988-01-01

The axial flow along the thimbles of the in core instrumentation induces vibration and shocks against their guides in the vessel, producing wear and even leakage, either on the thimbles, or on the instrumentation tube of the fuel assemblies. In order to characterize the phenomenon and help to reduce or suppress vibration of the thimbles, two methods have been developed and applied to French and Belgian reactors. The first one consists of an analysis of the shocks perceived on the thimbles tubes by accelerometers; this analysis, based on the study of statistical distribution (amplitude, impulse rate of shocks...) has allowed to choose among the different solutions proposed to solve the problem; this choice has been confirmed by direct wear measurements made later. The second method is based on spectral and time analysis of the fluctuating signals from in core neutron chambers. The correlation appears clearly between shocks and fluctuations. An estimation of the thimble model shape in the instrumentation tube of the assembly, has been made. These two analysis methods have been widely applied during start-up of the first eight 1300 MW reactors: they have contributed to solve the problem and to increase the availability of these plants. On the 900 MW reactors, where the problem is less severe, the approach has been to study the mechanical behaviour of one new plant, Chinon B3: all in core guide tubes have been equipped with accelerometers and an on line monitoring system directly transmits to Chatou the parameters of shocks, in order to define an acoustic parameter able to characterize wear, and so, to define a new type of maintenance for the thimbles. The first results are presented. (author)

Robust and transferable quantification of NMR spectral quality using IROC analysis

Science.gov (United States)

Zambrello, Matthew A.; Maciejewski, Mark W.; Schuyler, Adam D.; Weatherby, Gerard; Hoch, Jeffrey C.

2017-12-01

Non-Fourier methods are increasingly utilized in NMR spectroscopy because of their ability to handle nonuniformly-sampled data. However, non-Fourier methods present unique challenges due to their nonlinearity, which can produce nonrandom noise and render conventional metrics for spectral quality such as signal-to-noise ratio unreliable. The lack of robust and transferable metrics (i.e. applicable to methods exhibiting different nonlinearities) has hampered comparison of non-Fourier methods and nonuniform sampling schemes, preventing the identification of best practices. We describe a novel method, in situ receiver operating characteristic analysis (IROC), for characterizing spectral quality based on the Receiver Operating Characteristic curve. IROC utilizes synthetic signals added to empirical data as "ground truth", and provides several robust scalar-valued metrics for spectral quality. This approach avoids problems posed by nonlinear spectral estimates, and provides a versatile quantitative means of characterizing many aspects of spectral quality. We demonstrate applications to parameter optimization in Fourier and non-Fourier spectral estimation, critical comparison of different methods for spectrum analysis, and optimization of nonuniform sampling schemes. The approach will accelerate the discovery of optimal approaches to nonuniform sampling experiment design and non-Fourier spectrum analysis for multidimensional NMR.

Method for analyzing electromagnetic-force-induced vibration and noise analysis; Denjiryoku reiki ni yoru dendoki no shindo hoshaon kaisekiho

Energy Technology Data Exchange (ETDEWEB)

Shiohata, K.; Nemoto, K.; Nagawa, Y.; Sakamoto, S.; Kobayashi, T.; Ito, M.; Koharagi, H. [Hitachi, Ltd, Tokyo (Japan)

1998-11-01

In this analysis method, electromagnetic force calculated by 2-dimensional analysis is transformed into external force for 3-dimensional structural-vibration analysis. And a modeling procedure for a vibrating structure is developed. Further, a space-modal-resonance criteria which relates electromagnetic force to structural-vibration or noise is introduced. In the structural-vibration analysis, the finite element method is used; and in the noise analysis, the boundary element method is used. Finally, vibration and noise of an induction motor are calculated using this criteria. Consequently, high-accuracy modeling is achieved and noise the calculated by the simulation almost coincides with that obtained by experiments. And it is clarified that the-space-modal resonance criteria is effective in numerical simulation. 11 refs., 9 figs., 3 tabs.

Advances in nonlinear vibration analysis of structures. Part-I. Beams

Indian Academy of Sciences (India)

Unknown

element analysis of nonlinear beams under static and dynamic loads. ... linearization, substitution of inplane boundary conditions at element level rather .... Modelling the nonlinear vibration problems using finite elements, albeit with a couple.

Spectral Analysis of Rich Network Topology in Social Networks

Science.gov (United States)

Wu, Leting

2013-01-01

Social networks have received much attention these days. Researchers have developed different methods to study the structure and characteristics of the network topology. Our focus is on spectral analysis of the adjacency matrix of the underlying network. Recent work showed good properties in the adjacency spectral space but there are few…

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.

Experimental vibration level analysis of a Francis turbine

International Nuclear Information System (INIS)

Bucur, D M; Dunca, G; Calinoiu, C

2012-01-01

In this study the vibration level of a Francis turbine is investigated by experimental work in site. Measurements are carried out for different power output values, in order to highlight the influence of the operation regimes on the turbine behavior. The study focuses on the turbine shaft to identify the mechanical vibration sources and on the draft tube in order to identify the hydraulic vibration sources. Analyzing the vibration results, recommendations regarding the operation of the turbine, at partial load close to minimum values, in the middle of the operating domain or close to maximum values of electric power, can be made in order to keep relatively low levels of vibration. Finally, conclusions are drawn in order to present the real sources of the vibrations.

Comparison of sEMG processing methods during whole-body vibration exercise.

Science.gov (United States)

Lienhard, Karin; Cabasson, Aline; Meste, Olivier; Colson, Serge S

2015-12-01

The objective was to investigate the influence of surface electromyography (sEMG) processing methods on the quantification of muscle activity during whole-body vibration (WBV) exercises. sEMG activity was recorded while the participants performed squats on the platform with and without WBV. The spikes observed in the sEMG spectrum at the vibration frequency and its harmonics were deleted using state-of-the-art methods, i.e. (1) a band-stop filter, (2) a band-pass filter, and (3) spectral linear interpolation. The same filtering methods were applied on the sEMG during the no-vibration trial. The linear interpolation method showed the highest intraclass correlation coefficients (no vibration: 0.999, WBV: 0.757-0.979) with the comparison measure (unfiltered sEMG during the no-vibration trial), followed by the band-stop filter (no vibration: 0.929-0.975, WBV: 0.661-0.938). While both methods introduced a systematic bias (P interpolation method and the band-stop filter was comparable. The band-pass filter was in poor agreement with the other methods (ICC: 0.207-0.697), unless the sEMG(RMS) was corrected for the bias (ICC ⩾ 0.931, %LOA ⩽ 32.3). In conclusion, spectral linear interpolation or a band-stop filter centered at the vibration frequency and its multiple harmonics should be applied to delete the artifacts in the sEMG signals during WBV. With the use of a band-stop filter it is recommended to correct the sEMG(RMS) for the bias as this procedure improved its performance. Copyright © 2015 Elsevier Ltd. All rights reserved.

MEM spectral analysis for predicting influenza epidemics in Japan.

Science.gov (United States)

Sumi, Ayako; Kamo, Ken-ichi

2012-03-01

The prediction of influenza epidemics has long been the focus of attention in epidemiology and mathematical biology. In this study, we tested whether time series analysis was useful for predicting the incidence of influenza in Japan. The method of time series analysis we used consists of spectral analysis based on the maximum entropy method (MEM) in the frequency domain and the nonlinear least squares method in the time domain. Using this time series analysis, we analyzed the incidence data of influenza in Japan from January 1948 to December 1998; these data are unique in that they covered the periods of pandemics in Japan in 1957, 1968, and 1977. On the basis of the MEM spectral analysis, we identified the periodic modes explaining the underlying variations of the incidence data. The optimum least squares fitting (LSF) curve calculated with the periodic modes reproduced the underlying variation of the incidence data. An extension of the LSF curve could be used to predict the incidence of influenza quantitatively. Our study suggested that MEM spectral analysis would allow us to model temporal variations of influenza epidemics with multiple periodic modes much more effectively than by using the method of conventional time series analysis, which has been used previously to investigate the behavior of temporal variations in influenza data.

Origin of Spectral Band Patterns in the Cosmic Unidentified Infrared Emission

Science.gov (United States)

Álvaro Galué, Héctor; Díaz Leines, Grisell

2017-10-01

The cosmic unidentified infrared emission (UIE) band phenomenon is generally considered as indicative of free-flying polycyclic aromatic hydrocarbon molecules in space. However, a coherent explanation of emission spectral band patterns depending on astrophysical source is yet to be resolved under this attribution. Meanwhile astronomers have restored the alternative origin as due to amorphous carbon particles, but assigning spectral patterns to specific structural elements of particles is equally challenging. Here we report a physical principle in which inclusion of nonplanar structural defects in aromatic core molecular structures (π domains) induces spectral patterns typical of the phenomenon. We show that defects in model π domains modulate the electronic-vibration coupling that activates the delocalized π -electron contribution to aromatic vibrational modes. The modulation naturally disperses C =C stretch modes in band patterns that readily resemble the UIE bands in the elusive 6 - 9 μ m range. The electron-vibration interaction mechanics governing the defect-induced band patterns underscores the importance of π delocalization in the emergence of UIE bands. We discuss the global UIE band regularity of this range as compatible with an emission from the delocalized s p2 phase, as π domains, confined in disordered carbon mixed-phase aggregates.

Vibrational circulardichroism and IR spectral analysis as a test of theoretical conformational modeling for a cyclic hexapeptide

Czech Academy of Sciences Publication Activity Database

Bouř, Petr; Kim, J.; Kapitán, Josef; Hammer, R. P.; Huang, R.; Wu, L.; Keiderling, T. A.

2008-01-01

Roč. 20, č. 10 (2008), s. 1104-1119 ISSN 0899-0042 R&D Projects: GA ČR GA203/06/0420; GA ČR GA202/07/0732; GA AV ČR IAA400550702 Grant - others:NSF(US) CHE-0316014; NSF(US) CHE-0718543 Institutional research plan: CEZ:AV0Z40550506 Keywords : vibrational circular dichroism * peptide * conformation * ab initio Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.212, year: 2008

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...

Spectral map-analysis: a method to analyze gene expression data

OpenAIRE

Bijnens, Luc J.M.; Lewi, Paul J.; Göhlmann, Hinrich W.; Molenberghs, Geert; Wouters, Luc

2004-01-01

bioinformatics; biplot; correspondence factor analysis; data mining; data visualization; gene expression data; microarray data; multivariate exploratory data analysis; principal component analysis; Spectral map analysis

Analysis of spectral methods for the homogeneous Boltzmann equation

KAUST Repository

Filbet, Francis; Mouhot, Clé ment

2011-01-01

The development of accurate and fast algorithms for the Boltzmann collision integral and their analysis represent a challenging problem in scientific computing and numerical analysis. Recently, several works were devoted to the derivation of spectrally accurate schemes for the Boltzmann equation, but very few of them were concerned with the stability analysis of the method. In particular there was no result of stability except when the method was modified in order to enforce the positivity preservation, which destroys the spectral accuracy. In this paper we propose a new method to study the stability of homogeneous Boltzmann equations perturbed by smoothed balanced operators which do not preserve positivity of the distribution. This method takes advantage of the "spreading" property of the collision, together with estimates on regularity and entropy production. As an application we prove stability and convergence of spectral methods for the Boltzmann equation, when the discretization parameter is large enough (with explicit bound). © 2010 American Mathematical Society.

Analysis of spectral methods for the homogeneous Boltzmann equation

KAUST Repository

Filbet, Francis

2011-04-01

The development of accurate and fast algorithms for the Boltzmann collision integral and their analysis represent a challenging problem in scientific computing and numerical analysis. Recently, several works were devoted to the derivation of spectrally accurate schemes for the Boltzmann equation, but very few of them were concerned with the stability analysis of the method. In particular there was no result of stability except when the method was modified in order to enforce the positivity preservation, which destroys the spectral accuracy. In this paper we propose a new method to study the stability of homogeneous Boltzmann equations perturbed by smoothed balanced operators which do not preserve positivity of the distribution. This method takes advantage of the "spreading" property of the collision, together with estimates on regularity and entropy production. As an application we prove stability and convergence of spectral methods for the Boltzmann equation, when the discretization parameter is large enough (with explicit bound). © 2010 American Mathematical Society.

Development of varying magnetic field analysis technology caused by vibration of MRI apparatus

International Nuclear Information System (INIS)

Imamura, Yukinobu; Motoshiromizu, Hirofumi; Abe, Mitsushi; Watanabe, Hiroyuki; Takeuchi, Hiroyuki

2015-01-01

In Magnetic Resonance Imaging (MRI) apparatus, pulse current is energized to the gradient coils in a strong static magnetic field generated by the static magnetic poles. Since electromagnetic force (i.e. Lorentz force) is generated in the gradient coils, the MRI magnet system vibrates. On the other hand, vibration of the MRI magnet system is affected by electromagnetic force caused by static magnetic poles vibration. As the vibration of MRI magnet system causes magnetic field disturbance (so-called 'error magnetic field') and affect image quality, it is important to evaluate them in the design process. In this study, a varying magnetic field evaluation method for MRI magnet system was developed. Vibration and electromagnetic force is considered in the weak coupling formation using the Modal Magnetic Dumping (MMD) method. In the eddy current analysis by vibration, the displacement was considered in the magnetic field changes in the finite elements. Error magnetic field caused by equipment vibration was obtained by superposition of the static magnetic field fluctuation and the eddy current magnetic field. Then open type MRI magnet was evaluated by the proposed methodology. A a result, vibration of static magnet poles were suppressed by magnetic dumping at 50 Hz or less and eddy current magnetic field was dominant at 50 Hz or more. (author)

WAVELETS AND PRINCIPAL COMPONENT ANALYSIS METHOD FOR VIBRATION MONITORING OF ROTATING MACHINERY

OpenAIRE

Bendjama, Hocine; S. Boucherit, Mohamad

2017-01-01

Fault diagnosis is playing today a crucial role in industrial systems. To improve reliability, safety and efficiency advanced monitoring methods have become increasingly important for many systems. The vibration analysis method is essential in improving condition monitoring and fault diagnosis of rotating machinery. Effective utilization of vibration signals depends upon effectiveness of applied signal processing techniques. In this paper, fault diagnosis is performed using a com...

Interferometric and nonlinear-optical spectral-imaging techniques for outer space and live cells

Science.gov (United States)

Itoh, Kazuyoshi

2015-12-01

Multidimensional signals such as the spectral images allow us to have deeper insights into the natures of objects. In this paper the spectral imaging techniques that are based on optical interferometry and nonlinear optics are presented. The interferometric imaging technique is based on the unified theory of Van Cittert-Zernike and Wiener-Khintchine theorems and allows us to retrieve a spectral image of an object in the far zone from the 3D spatial coherence function. The retrieval principle is explained using a very simple object. The promising applications to space interferometers for astronomy that are currently in progress will also be briefly touched on. An interesting extension of interferometric spectral imaging is a 3D and spectral imaging technique that records 4D information of objects where the 3D and spectral information is retrieved from the cross-spectral density function of optical field. The 3D imaging is realized via the numerical inverse propagation of the cross-spectral density. A few techniques suggested recently are introduced. The nonlinear optical technique that utilizes stimulated Raman scattering (SRS) for spectral imaging of biomedical targets is presented lastly. The strong signals of SRS permit us to get vibrational information of molecules in the live cell or tissue in real time. The vibrational information of unstained or unlabeled molecules is crucial especially for medical applications. The 3D information due to the optical nonlinearity is also the attractive feature of SRS spectral microscopy.

Energy calibration issues in nuclear resonant vibrational spectroscopy: observing small spectral shifts and making fast calibrations.

Science.gov (United States)

Wang, Hongxin; Yoda, Yoshitaka; Dong, Weibing; Huang, Songping D

2013-09-01

The conventional energy calibration for nuclear resonant vibrational spectroscopy (NRVS) is usually long. Meanwhile, taking NRVS samples out of the cryostat increases the chance of sample damage, which makes it impossible to carry out an energy calibration during one NRVS measurement. In this study, by manipulating the 14.4 keV beam through the main measurement chamber without moving out the NRVS sample, two alternative calibration procedures have been proposed and established: (i) an in situ calibration procedure, which measures the main NRVS sample at stage A and the calibration sample at stage B simultaneously, and calibrates the energies for observing extremely small spectral shifts; for example, the 0.3 meV energy shift between the 100%-(57)Fe-enriched [Fe4S4Cl4](=) and 10%-(57)Fe and 90%-(54)Fe labeled [Fe4S4Cl4](=) has been well resolved; (ii) a quick-switching energy calibration procedure, which reduces each calibration time from 3-4 h to about 30 min. Although the quick-switching calibration is not in situ, it is suitable for normal NRVS measurements.

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.

Nonlinear Vibrations of Cantilever Timoshenko Beams: A Homotopy Analysis

Directory of Open Access Journals (Sweden)

Shahram Shahlaei-Far

Full Text Available Abstract This study analyzes the fourth-order nonlinear free vibration of a Timoshenko beam. We discretize the governing differential equation by Galerkin's procedure and then apply the homotopy analysis method (HAM to the obtained ordinary differential equation of the generalized coordinate. We derive novel analytical solutions for the nonlinear natural frequency and displacement to investigate the effects of rotary inertia, shear deformation, pre-tensile loads and slenderness ratios on the beam. In comparison to results achieved by perturbation techniques, this study demonstrates that a first-order approximation of HAM leads to highly accurate solutions, valid for a wide range of amplitude vibrations, of a high-order strongly nonlinear problem.

Vibrational dynamics of aqueous hydroxide solutions probed using broadband 2DIR spectroscopy

International Nuclear Information System (INIS)

Mandal, Aritra; Tokmakoff, Andrei

2015-01-01

We employed ultrafast transient absorption and broadband 2DIR spectroscopy to study the vibrational dynamics of aqueous hydroxide solutions by exciting the O–H stretch vibrations of the strongly hydrogen-bonded hydroxide solvation shell water and probing the continuum absorption of the solvated ion between 1500 and 3800 cm −1 . We observe rapid vibrational relaxation processes on 150–250 fs time scales across the entire probed spectral region as well as slower vibrational dynamics on 1–2 ps time scales. Furthermore, the O–H stretch excitation loses its frequency memory in 180 fs, and vibrational energy exchange between bulk-like water vibrations and hydroxide-associated water vibrations occurs in ∼200 fs. The fast dynamics in this system originate in strong nonlinear coupling between intra- and intermolecular vibrations and are explained in terms of non-adiabatic vibrational relaxation. These measurements indicate that the vibrational dynamics of the aqueous hydroxide complex are faster than the time scales reported for long-range transport of protons in aqueous hydroxide solutions

Vibration behavior of PWR reactor internals Model experiments and analysis

International Nuclear Information System (INIS)

Assedo, R.; Dubourg, M.; Livolant, M.; Epstein, A.

1975-01-01

In the late 1971, the CEA and FRAMATOME decided to undertake a comprehensive joint program of studying the vibration behavior of PWR internals of the 900 MWe, 50 cycle, 3 loop reactor series being built by FRAMATOME in France. The PWR reactor internals are submitted to several sources of excitation during normal operation. Two main sources of excitation may effect the internals behavior: the large flow turbulences which could generate various instabilities such as: vortex shedding: the pump pressure fluctuations which could generate acoustic noise in the circuit at frequencies corresponding to shaft speed frequencies or blade passing frequencies, and their respective harmonics. The flow induced vibrations are of complex nature and the approach selected, for this comprehensive program, is semi-empirical and based on both theoretical analysis and experiments on a reduced scale model and full scale internals. The experimental support of this program consists of: the SAFRAN test loop which consists of an hydroelastic similitude of a 1/8 scale model of a PWR; harmonic vibration tests in air performed on full scale reactor internals in the manufacturing shop; the GENNEVILLIERS facilities which is a full flow test facility of primary pump; the measurements carried out during start up on the Tihange reactor. This program will be completed in April 1975. The results of this program, the originality of which consists of studying separately the effects of random excitations and acoustic noises, on the internals behavior, and by establishing a comparison between experiments and analysis, will bring a major contribution for explaining the complex vibration phenomena occurring in a PWR

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.

Crystal structure, vibrational and DFT simulation studies of melaminium dihydrogen phosphite monohydrate

Science.gov (United States)

Arjunan, V.; Kalaivani, M.; Marchewka, M. K.; Mohan, S.

2013-08-01

The crystal structure investigations of melamine with phosphorous acid, namely melaminium dihydrogenphosphite monohydrate (C3N6H7·H2PO3·H2O) have been investigated by means of single crystal X-ray diffraction method. The title compound crystallizes in monoclinic crystal system, and the space group is P21/c with a = 10.069 Å, b = 21.592 Å, c = 12.409 Å and Z = 12. The vibrational assignments and analysis of melaminium dihydrogen phosphite monohydrate have also been performed by FTIR, FT-Raman and far-infrared spectral studies. The quantum chemical simulations were performed with DFT (B3LYP) method using 6-31G**, cc-pVTZ, and 6-311++G** basis sets to determine the energy, structural, thermodynamic parameters and vibrational frequencies of melaminium dihydrogen phosphite monohydrate. The hydrogen atom from phosphorous acid was transferred to the melamine molecule giving the singly protonated melaminium cation. The ability of ions to form spontaneous three-dimensional structure through weak Osbnd H···O and Nsbnd H···O hydrogen bonds shows notable vibrational effects.

Modelling of magnetostriction of transformer magnetic core for vibration analysis

Science.gov (United States)

Marks, Janis; Vitolina, Sandra

2017-12-01

Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.

Modelling of magnetostriction of transformer magnetic core for vibration analysis

Directory of Open Access Journals (Sweden)

Marks Janis

2017-12-01

Full Text Available Magnetostriction is a phenomenon occurring in transformer core in normal operation mode. Yet in time, it can cause the delamination of magnetic core resulting in higher level of vibrations that are measured on the surface of transformer tank during diagnostic tests. The aim of this paper is to create a model for evaluating elastic deformations in magnetic core that can be used for power transformers with intensive vibrations in order to eliminate magnetostriction as a their cause. Description of the developed model in Matlab and COMSOL software is provided including restrictions concerning geometry and properties of materials, and the results of performed research on magnetic core anisotropy are provided. As a case study modelling of magnetostriction for 5-legged 200 MVA power transformer with the rated voltage of 13.8/137kV is conducted, based on which comparative analysis of vibration levels and elastic deformations is performed.

Silicon Micromachined Sensor for Broadband Vibration Analysis

Science.gov (United States)

Gutierrez, Adolfo; Edmans, Daniel; Cormeau, Chris; Seidler, Gernot; Deangelis, Dave; Maby, Edward

1995-01-01

The development of a family of silicon based integrated vibration sensors capable of sensing mechanical resonances over a broad range of frequencies with minimal signal processing requirements is presented. Two basic general embodiments of the concept were designed and fabricated. The first design was structured around an array of cantilever beams and fabricated using the ARPA sponsored multi-user MEMS processing system (MUMPS) process at the Microelectronics Center of North Carolina (MCNC). As part of the design process for this first sensor, a comprehensive finite elements analysis of the resonant modes and stress distribution was performed using PATRAN. The dependence of strain distribution and resonant frequency response as a function of Young's modulus in the Poly-Si structural material was studied. Analytical models were also studied. In-house experimental characterization using optical interferometry techniques were performed under controlled low pressure conditions. A second design, intended to operate in a non-resonant mode and capable of broadband frequency response, was proposed and developed around the concept of a cantilever beam integrated with a feedback control loop to produce a null mode vibration sensor. A proprietary process was used to integrat a metal-oxide semiconductor (MOS) sensing device, with actuators and a cantilever beam, as part of a compatible process. Both devices, once incorporated as part of multifunction data acquisition and telemetry systems will constitute a useful system for NASA launch vibration monitoring operations. Satellite and other space structures can benefit from the sensor for mechanical condition monitoring functions.

Flow-induced vibration analysis of heat exchanger and steam generator designs

International Nuclear Information System (INIS)

Pettigrew, M.J.; Sylvestre, Y.; Campagna, A.O.

1977-08-01

Tube and shell heat exchange components such as steam generators, heat exchangers and condensers are essential parts of CANDU nuclear power stations. Excessive flow-induced vibration may cause tube failures by fatigue or more likely by fretting-wear. Such failures may lead to station shutdowns that are very undesirable in terms of lost production. Hence good performance and reliability dictate a thorough flow-induced vibration analysis at the design stage. This paper presents our approach and techniques in this respect. (author)

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.

Vibrational analysis of submerged cylindrical shells based on elastic foundations

International Nuclear Information System (INIS)

Shah, A.G.; Naeem, M.N.

2014-01-01

In this study a vibration analysis was performed of an isotropic cylindrical shell submerged in fluid, resting on Winkler and Pasternak elastic foundations for simply supported boundary condition. Love's thin shell theory was exploited for strain- and curvature- displacement relationship. Shell problem was solved by using wave propagation approach. Influence of fluid and Winkler as well as Pasternak elastic foundations were studied on the natural frequencies of submerged isotropic cylindrical shells. Results were validated by comparing with the existing results in literature. Vibration, Submerged cylindrical shell, Love's thin shell theory, Wave propagation method, Winkler and Pasternak foundations. (author)

DFT study of conformational and vibrational characteristics of 2-(2-hydroxyphenyl)benzothiazole molecule.

Science.gov (United States)

Pandey, Urmila; Srivastava, Mayuri; Singh, R P; Yadav, R A

2014-08-14

The conformational and IR and Raman spectral studies of 2-(2-hydroxyphenyl)benzothiazole have been carried out by using the DFT method at the B3LYP/6-311++G(**) level. The detailed vibrational assignments have been done on the basis of calculated potential energy distributions. Comparative studies of molecular geometries, atomic charges and vibrational fundamentals of all the conformers have been made. There are four possible conformers for this molecule. The optimized geometrical parameters obtained by B3LYP/6-311++G(**) method showed good agreement with the experimental X-ray data. The atomic polar tensor (APT) charges, Mulliken atomic charges, natural bond orbital (NBO) analysis and HOMO-LUMO energy gap of HBT and its conformers were also computed. Copyright © 2014 Elsevier B.V. All rights reserved.

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

A combined dynamic analysis method for geometrically nonlinear vibration isolators with elastic rings

Science.gov (United States)

Hu, Zhan; Zheng, Gangtie

2016-08-01

A combined analysis method is developed in the present paper for studying the dynamic properties of a type of geometrically nonlinear vibration isolator, which is composed of push-pull configuration rings. This method combines the geometrically nonlinear theory of curved beams and the Harmonic Balance Method to overcome the difficulty in calculating the vibration and vibration transmissibility under large deformations of the ring structure. Using the proposed method, nonlinear dynamic behaviors of this isolator, such as the lock situation due to the coulomb damping and the usual jump resulting from the nonlinear stiffness, can be investigated. Numerical solutions based on the primary harmonic balance are first verified by direct integration results. Then, the whole procedure of this combined analysis method is demonstrated and validated by slowly sinusoidal sweeping experiments with different amplitudes of the base excitation. Both numerical and experimental results indicate that this type of isolator behaves as a hardening spring with increasing amplitude of the base excitation, which makes it suitable for isolating both steady-state vibrations and transient shocks.

Modelling and Analysis of Vibrations in a UAV Helicopter with a Vision System

Directory of Open Access Journals (Sweden)

G. Nicolás Marichal Plasencia

2012-11-01

Full Text Available The analysis of the nature and damping of unwanted vibrations on Unmanned Aerial Vehicle (UAV helicopters are important tasks when images from on-board vision systems are to be obtained. In this article, the authors model a UAV system, generate a range of vibrations originating in the main rotor and design a control methodology in order to damp these vibrations. The UAV is modelled using VehicleSim, the vibrations that appear on the fuselage are analysed to study their effects on the on-board vision system by using Simmechanics software. Following this, the authors present a control method based on an Adaptive Neuro-Fuzzy Inference System (ANFIS to achieve satisfactory damping results over the vision system on board.

Parametric analysis of protective grid flow induced vibration

Energy Technology Data Exchange (ETDEWEB)

Ryu, Jooyoung; Eom, Kyongbo; Jeon, Sangyoun; Suh, Jungmin [KEPCO NF Co., Daejeon (Korea, Republic of)

2012-10-15

Protective grid (P-grid) flow-induced vibration in a nuclear power reactor is one of the critical factors for the mechanical integrity of a nuclear fuel. The P-grid is located at the lower most position above the bottom nozzle of the nuclear fuel as shown in Fig. 1, and it is required for not only filtering debris, but also supporting fuel rods. On the other hand, P-grid working conditions installed in a nuclear fuel in a reactor are severe in terms of flow speed, temperature and pressure. Considering such a severe condition of P-grid's functional performance in working environment, excessive vibration could be developed. Furthermore, if the P-grid is exposed to high levels of excessive vibration over a long period of time, fatigue failure could be unavoidable. Therefore, it is important to reduce excessive vibration while maintaining P-grid's own functional performance. KEPCO Nuclear Fuel has developed a test facility - Investigation Flow-induced Vibration (INFINIT) - to study flow-induced vibration caused by flowing coolant at various flow rates. To investigate specific relationships between configuration of P-grid and flow-induced vibration characteristics, several types of the P-grids were tested in INFINIT facility. And, based on the test results through parametric studies, the flow-induced vibration characteristics could be analyzed, and critical design parameters were found.

Random vibrations theory and practice

CERN Document Server

Wirsching, Paul H; Ortiz, Keith

1995-01-01

Random Vibrations: Theory and Practice covers the theory and analysis of mechanical and structural systems undergoing random oscillations due to any number of phenomena— from engine noise, turbulent flow, and acoustic noise to wind, ocean waves, earthquakes, and rough pavement. For systems operating in such environments, a random vibration analysis is essential to the safety and reliability of the system. By far the most comprehensive text available on random vibrations, Random Vibrations: Theory and Practice is designed for readers who are new to the subject as well as those who are familiar with the fundamentals and wish to study a particular topic or use the text as an authoritative reference. It is divided into three major sections: fundamental background, random vibration development and applications to design, and random signal analysis. Introductory chapters cover topics in probability, statistics, and random processes that prepare the reader for the development of the theory of random vibrations a...

Vibration spectra of single atomic nanocontacts

International Nuclear Information System (INIS)

Bourahla, B; Khater, A; Rafil, O; Tigrine, R

2006-01-01

This paper introduces a simple model for an atomic nanocontact, where its mechanical properties are analysed by calculating numerically the local spectral properties at the contact atom and the nearby atoms. The standard methodology for calculating phonon spectral densities is extended to enable the calculation of localized contact modes and local density of states (DOS). The model system considered for the nanocontact consists of two sets of triple parallel semi-infinite atomic chains joined by a single atom in between. The matching method is used, in the harmonic approximation, to calculate the local Green's functions for the irreducible set of sites that constitute the inhomogeneous nanocontact domain. The Green's functions yield the vibration spectra and the DOS for the atomic sites. These are numerically calculated for different cases of elastic hardening and softening of the nanocontact domain. The purpose is to investigate how the local dynamics respond to local changes in the elastic environment. The analysis of the spectra and of the DOS identifies characteristic features and demonstrates the central role of a core subset of these sites for the dynamics of the nanocontact. The system models a situation which may be appropriate for contact atomic force microscopy

Bistable flow spectral analysis. Repercussions on jet pumps

International Nuclear Information System (INIS)

Gavilan Moreno, C.J.

2011-01-01

Highlights: → The most important thing in this paper, is the spectral characterization of the bistable flow in a Nuclear Power Plant. → This paper goes deeper in the effect of the bistable flow over the jet pump and the induced vibrations. → The jet pump frequencies are very close to natural jet pump frequencies, in the 3rd and 6th mode. - Abstract: There have been many attempts at characterizing and predicting bistable flow in boiling water reactors (BWRs). Nevertheless, in most cases the results have only managed to develop models that analytically reproduce the phenomenon (). Modeling has been forensic in all cases, while the capacity of the model focus on determining the exclusion areas on the recirculation flow map. The bistability process is known by its effects given there is no clear definition of its causal process. In the 1980s, Hitachi technicians () managed to reproduce bistable flow in the laboratory by means of pipe geometry, similar to that which is found in recirculation loops. The result was that the low flow pattern is formed by the appearance of a quasi stationary, helicoidal vortex in the recirculation collector's branches. This vortex creates greater frictional losses than regions without vortices, at the same discharge pressure. Neither the behavior nor the dynamics of these vortices were characterized in this paper. The aim of this paper is to characterize these vortices in such a way as to enable them to provide their own frequencies and their later effect on the jet pumps. The methodology used in this study is similar to the one used previously when analyzing the bistable flow in tube arrays with cross flow (). The method employed makes use of the power spectral density function. What differs is the field of application. We will analyze a Loop B with a bistable flow and compare the high and low flow situations. The same analysis will also be carried out on the loop that has not developed the bistable flow (Loop A) at the same moments

Power spectral analysis of heart rate in hyperthyroidism.

Science.gov (United States)

Cacciatori, V; Bellavere, F; Pezzarossa, A; Dellera, A; Gemma, M L; Thomaseth, K; Castello, R; Moghetti, P; Muggeo, M

1996-08-01

The aim of the present study was to evaluate the impact of hyperthyroidism on the cardiovascular system by separately analyzing the sympathetic and parasympathetic influences on heart rate. Heart rate variability was evaluated by autoregressive power spectral analysis. This method allows a reliable quantification of the low frequency (LF) and high frequency (HF) components of the heart rate power spectral density; these are considered to be under mainly sympathetic and pure parasympathetic control, respectively. In 10 newly diagnosed untreated hyperthyroid patients with Graves' disease, we analyzed power spectral density of heart rate cyclic variations at rest, while lying, and while standing. In addition, heart rate variations during deep breathing, lying and standing, and Valsalva's maneuver were analyzed. The results were compared to those obtained from 10 age-, sex-, and body mass index-matched control subjects. In 8 hyperthyroid patients, the same evaluation was repeated after the induction of stable euthyroidism by methimazole. Heart rate power spectral analysis showed a sharp reduction of HF components in hyperthyroid subjects compared to controls [lying, 13.3 +/- 4.1 vs. 32.0 +/- 5.6 normalized units (NU; P hyperthyroid subjects while both lying (11.3 +/- 4.5 vs. 3.5 +/- 1.1; P hyperthyroid patients than in controls (1.12 +/- 0.03 vs. 1.31 +/- 0.04; P activity and, thus, a relative hypersympathetic tone.

Spectral analysis of full field digital mammography data

International Nuclear Information System (INIS)

Heine, John J.; Velthuizen, Robert P.

2002-01-01

The spectral content of mammograms acquired from using a full field digital mammography (FFDM) system are analyzed. Fourier methods are used to show that the FFDM image power spectra obey an inverse power law; in an average sense, the images may be considered as 1/f fields. Two data representations are analyzed and compared (1) the raw data, and (2) the logarithm of the raw data. Two methods are employed to analyze the power spectra (1) a technique based on integrating the Fourier plane with octave ring sectioning developed previously, and (2) an approach based on integrating the Fourier plane using rings of constant width developed for this work. Both methods allow theoretical modeling. Numerical analysis indicates that the effects due to the transformation influence the power spectra measurements in a statistically significant manner in the high frequency range. However, this effect has little influence on the inverse power law estimation for a given image regardless of the data representation or the theoretical analysis approach. The analysis is presented from two points of view (1) each image is treated independently with the results presented as distributions, and (2) for a given representation, the entire image collection is treated as an ensemble with the results presented as expected values. In general, the constant ring width analysis forms the foundation for a spectral comparison method for finding spectral differences, from an image distribution sense, after applying a nonlinear transformation to the data. The work also shows that power law estimation may be influenced due to the presence of noise in the higher frequency range, which is consistent with the known attributes of the detector efficiency. The spectral modeling and inverse power law determinations obtained here are in agreement with that obtained from the analysis of digitized film-screen images presented previously. The form of the power spectrum for a given image is approximately 1/f 2�

Global spectral graph wavelet signature for surface analysis of carpal bones

Science.gov (United States)

Masoumi, Majid; Rezaei, Mahsa; Ben Hamza, A.

2018-02-01

Quantitative shape comparison is a fundamental problem in computer vision, geometry processing and medical imaging. In this paper, we present a spectral graph wavelet approach for shape analysis of carpal bones of the human wrist. We employ spectral graph wavelets to represent the cortical surface of a carpal bone via the spectral geometric analysis of the Laplace-Beltrami operator in the discrete domain. We propose global spectral graph wavelet (GSGW) descriptor that is isometric invariant, efficient to compute, and combines the advantages of both low-pass and band-pass filters. We perform experiments on shapes of the carpal bones of ten women and ten men from a publicly-available database of wrist bones. Using one-way multivariate analysis of variance (MANOVA) and permutation testing, we show through extensive experiments that the proposed GSGW framework gives a much better performance compared to the global point signature embedding approach for comparing shapes of the carpal bones across populations.

Multi-spectral Image Analysis for Astaxanthin Coating Classification

DEFF Research Database (Denmark)

Ljungqvist, Martin Georg; Ersbøll, Bjarne Kjær; Nielsen, Michael Engelbrecht

2011-01-01

Industrial quality inspection using image analysis on astaxanthin coating in aquaculture feed pellets is of great importance for automatic production control. In this study multi-spectral image analysis of pellets was performed using LDA, QDA, SNV and PCA on pixel level and mean value of pixels...

XRD, vibrational spectra and quantum chemical studies of an anticancer drug: 6-Mercaptopurine.

Science.gov (United States)

Kumar, S Suresh; Athimoolam, S; Sridhar, B

2015-07-05

The single crystal of the hydrated anticancer drug, 6-Mercaptopurine (6-MP), has been grown by slow evaporation technique under room temperature. The structure was determined by single crystal X-ray diffraction. The vibrational spectral analysis was carried out using Laser Raman and FT-IR spectroscopy in the range of 3300-100 and 4000-400 cm(-1). The single crystal X-ray studies shows that the crystal packing is dominated by N-H⋯O and O-H⋯N classical hydrogen bonds leading to a hydrogen bonded ensemble. This classical hydrogen bonds were further connected through O-H⋯S hydrogen bond to form two primary ring R4(4)(16) and R4(4)(12) motifs. These two primary ring motifs are interlinked with each other to build a ladder like structure. These ladders are connected through N-H⋯N hydrogen bond along c-axis of the unit cell through chain C(5) motifs. Further, the strength of the hydrogen bonds is studied through vibrational spectral measurements. The shifting of bands due to the intermolecular interactions was also analyzed in the solid crystalline state. Geometrical optimizations of the drug molecule were done by Density Functional Theory (DFT) using the B3LYP function and Hartree-Fock (HF) level with 6-311++G(d,p) basis set. The optimized molecular geometry and computed vibrational spectra are compared with experimental results which show significant agreement. The natural bond orbital (NBO) analysis was carried out to interpret hyperconjugative interaction and intramolecular charge transfer (ICT). The chemical hardness, electro-negativity and chemical potential of the molecule are carried out by HOMO-LUMO plot. In which, the frontier orbitals has lower band gap value indicating the possible pharmaceutical activity of the molecule. Copyright © 2015 Elsevier B.V. All rights reserved.

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.

A bandwidth correction to the Allegri-Zhang solution for accelerated random vibration testing

Directory of Open Access Journals (Sweden)

Benasciutti Denis

2018-01-01

Full Text Available In 2008, Allegri and Zhang published a study [Int. J. Fatigue. 2008, 30(6:967-977] in which they provided an exact analytical solution to the inverse scaling law for accelerated vibration tests of linear systems submitted to stationary Gaussian excitations By combining finite element analysis with multiaxial spectral methods defined in the frequency-domain, their solution generalised the simple inverse power law model suggested in some standards. The solution adopted the “equivalent von Mises stress” multiaxial criterion combined with the narrow-band damage expression. This work aims to propose a bandwidth correction to the original Allegri-Zhang solution to account for the actual spectral banwidth of the local multiaxial stress. The corrected Allegri-Zhang solution is also extended to another multiaxial spectral method, namely the “Projection-by-Projection” criterion. A numerical example is finally discussed, in which the corrected solution is applied to an L-shaped beam submitted to random accelerations.

Multitaper spectral analysis of atmospheric radar signals

Directory of Open Access Journals (Sweden)

V. K. Anandan

2004-11-01

Full Text Available Multitaper spectral analysis using sinusoidal taper has been carried out on the backscattered signals received from the troposphere and lower stratosphere by the Gadanki Mesosphere-Stratosphere-Troposphere (MST radar under various conditions of the signal-to-noise ratio. Comparison of study is made with sinusoidal taper of the order of three and single tapers of Hanning and rectangular tapers, to understand the relative merits of processing under the scheme. Power spectra plots show that echoes are better identified in the case of multitaper estimation, especially in the region of a weak signal-to-noise ratio. Further analysis is carried out to obtain three lower order moments from three estimation techniques. The results show that multitaper analysis gives a better signal-to-noise ratio or higher detectability. The spectral analysis through multitaper and single tapers is subjected to study of consistency in measurements. Results show that the multitaper estimate is better consistent in Doppler measurements compared to single taper estimates. Doppler width measurements with different approaches were studied and the results show that the estimation was better in the multitaper technique in terms of temporal resolution and estimation accuracy.

Energetics and Vibrational Analysis of Methyl Salicylate Isomers

Science.gov (United States)

Massaro, Richard D.; Dai, Yafei; Blaisten-Barojas, Estela

2009-08-01

Energetics and vibrational analysis study of six isomers of methyl salicylate in their singlet ground state and first excited triple state is put forward in this work at the density functional theory level and large basis sets. The ketoB isomer is the lowest energy isomer, followed by its rotamer ketoA. For both ketoB and ketoA their enolized tautomers are found to be stable as well as their open forms that lack the internal hydrogen bond. The calculated vibrational spectra are in excellent agreement with IR experiments of methyl salicylate in the vapor phase. It is demonstrated that solvent effects have a weak influence on the stability of these isomers. The ionization reaction from ketoB to ketoA shows a high barrier of 0.67 eV ensuring that thermal and chemical equilibria yield systems containing mostly the ketoB isomer at normal conditions.

Vibration analysis on driver’s seat of agricultural tractors during tillage tests

International Nuclear Information System (INIS)

Gialamas, T.; Gravalos, I.; Kateris, D.; Xyradakis, P.; Dimitriadis, C.

2016-01-01

The vibration of the driver’s seat of agricultural tractors was investigated during three alternative tillage operations. Three tractors including a range of specifications were considered, at a range of forward speeds. The interactions between the tractors, implements and speeds were examined using the SPSS program and the GLM-ANOVA method. The results analysis indicated that the tractors played the first major role in vibration development in the lateral axis and was followed by the implements. In contrast, the implements played the first major role in the development of vibration in the horizontal axis and are followed by factor tractors. The statistically significant effect in vertical and horizontal axes shows the factor implements. In addition, the statistically significant effect in the vertical and lateral axes shows again the implements to be the most significant factor. Of the implements, the plough shows the highest vibration and displays statistically significant difference in comparison with the other implements.

Vibration analysis on driver’s seat of agricultural tractors during tillage tests

Energy Technology Data Exchange (ETDEWEB)

Gialamas, T.; Gravalos, I.; Kateris, D.; Xyradakis, P.; Dimitriadis, C.

2016-07-01

The vibration of the driver’s seat of agricultural tractors was investigated during three alternative tillage operations. Three tractors including a range of specifications were considered, at a range of forward speeds. The interactions between the tractors, implements and speeds were examined using the SPSS program and the GLM-ANOVA method. The results analysis indicated that the tractors played the first major role in vibration development in the lateral axis and was followed by the implements. In contrast, the implements played the first major role in the development of vibration in the horizontal axis and are followed by factor tractors. The statistically significant effect in vertical and horizontal axes shows the factor implements. In addition, the statistically significant effect in the vertical and lateral axes shows again the implements to be the most significant factor. Of the implements, the plough shows the highest vibration and displays statistically significant difference in comparison with the other implements.

Processing of spectral X-ray data with principal components analysis

CERN Document Server

Butler, A P H; Cook, N J; Butzer, J; Schleich, N; Tlustos, L; Scott, N; Grasset, R; de Ruiter, N; Anderson, N G

2011-01-01

The goal of the work was to develop a general method for processing spectral x-ray image data. Principle component analysis (PCA) is a well understood technique for multivariate data analysis and so was investigated. To assess this method, spectral (multi-energy) computed tomography (CT) data was obtained using a Medipix2 detector in a MARS-CT (Medipix All Resolution System). PCA was able to separate bone (calcium) from two elements with k-edges in the X-ray spectrum used (iodine and barium) within a mouse. This has potential clinical application in dual-energy CT systems and future Medipix3 based spectral imaging where up to eight energies can be recorded simultaneously with excellent energy resolution. (c) 2010 Elsevier B.V. All rights reserved.

Hot Ground Vibration Tests

Data.gov (United States)

National Aeronautics and Space Administration — Ground vibration tests or modal surveys are routinely conducted to support flutter analysis for subsonic and supersonic vehicles. However, vibration testing...

Multivariate spectral-analysis of movement-related EEG data

International Nuclear Information System (INIS)

Andrew, C. M.

1997-01-01

The univariate method of event-related desynchronization (ERD) analysis, which quantifies the temporal evolution of power within specific frequency bands from electroencephalographic (EEG) data recorded during a task or event, is extended to an event related multivariate spectral analysis method. With this method, time courses of cross-spectra, phase spectra, coherence spectra, band-averaged coherence values (event-related coherence, ERCoh), partial power spectra and partial coherence spectra are estimated from an ensemble of multivariate event-related EEG trials. This provides a means of investigating relationships between EEG signals recorded over different scalp areas during the performance of a task or the occurrence of an event. The multivariate spectral analysis method is applied to EEG data recorded during three different movement-related studies involving discrete right index finger movements. The first study investigates the impact of the EEG derivation type on the temporal evolution of interhemispheric coherence between activity recorded at electrodes overlying the left and right sensorimotor hand areas during cued finger movement. The question results whether changes in coherence necessarily reflect changes in functional coupling of the cortical structures underlying the recording electrodes. The method is applied to data recorded during voluntary finger movement and a hypothesis, based on an existing global/local model of neocortical dynamics, is formulated to explain the coherence results. The third study applies partial spectral analysis too, and investigates phase relationships of, movement-related data recorded from a full head montage, thereby providing further results strengthening the global/local hypothesis. (author)

Application of fluorescent and vibration spectroscopy for septic serum human albumin structure deformation during pathology

Science.gov (United States)

Zyubin, A.; Konstantinova, E.; Slezhkin, V.; Matveeva, K.; Samusev, I.; Bryukhanov, V.

2017-12-01

In this paper we perform results of conformational analysis of septic human serum albumin (HSA) carried out by Raman spectroscopy (RS), infrared (IR) spectroscopy and fluorescent spectroscopy. The main vibrational groups were identified and analyzed for septic HSA and its health control. Comparison between Raman and IR results were done. Fluorescent spectral changes of Trp-214 group were analyzed. Application of Raman, IR spectroscopy, fluorescent spectroscopy for conformational changes study of HSA during pathology were shown.

Vibrational and electronic investigations, thermodynamic parameters, HOMO and LUMO analysis on Lornoxicam by density functional theory

Science.gov (United States)

Suhasini, M.; Sailatha, E.; Gunasekaran, S.; Ramkumaar, G. R.

2015-11-01

The Fourier transform infrared (FT-IR) and FT-Raman spectra of Lornoxicam were recorded in the region 4000-450 cm-1 and 4000-50 cm-1 respectively. Density functional theory (DFT) has been used to calculate the optimized geometrical parameters, atomic charges, and vibrational wavenumbers and intensity of the vibrational bands. The computed vibrational wave numbers were compared with the FT-IR and FT-Raman experimental data. The computational calculations at DFT/B3LYP level with 6-31G(d,p) and 6-31++G(d,p) basis sets. The complete vibrational assignments were performed on the basis of the potential energy distribution (PED) of the Vibrational modes calculated using Vibrational Energy Distribution Analysis (VEDA 4) program. The oscillator's strength calculated by TD-DFT and Lornoxicam is approach complement with the experimental findings. The NMR chemical shifts 13C and 1H were recorded and calculated using the gauge independent atomic orbital (GIAO) method. The Natural charges and intermolecular contacts have been interpreted using Natural Bond orbital (NBO) analysis and the HOMO-LUMO energy gap has been calculated. The thermodynamic properties like Entropy, Enthalpy, Specific heat capacity and zero vibrational energy have been calculated. Besides, molecular electrostatic potential (MEP) was investigated using theoretical calculations.

Terahertz Josephson spectral analysis and its applications

Science.gov (United States)

Snezhko, A. V.; Gundareva, I. I.; Lyatti, M. V.; Volkov, O. Y.; Pavlovskiy, V. V.; Poppe, U.; Divin, Y. Y.

2017-04-01

Principles of Hilbert-transform spectral analysis (HTSA) are presented and advantages of the technique in the terahertz (THz) frequency range are discussed. THz HTSA requires Josephson junctions with high values of characteristic voltages I c R n and dynamics described by a simple resistively shunted junction (RSJ) model. To meet these requirements, [001]- and [100]-tilt YBa2Cu3O7-x bicrystal junctions with deviations from the RSJ model less than 1% have been developed. Demonstrators of Hilbert-transform spectrum analyzers with various cryogenic environments, including integration into Stirling coolers, are described. Spectrum analyzers have been characterized in the spectral range from 50 GHz to 3 THz. Inside a power dynamic range of five orders, an instrumental function of the analyzers has been found to have a Lorentz form around a single frequency of 1.48 THz with a spectral resolution as low as 0.9 GHz. Spectra of THz radiation from optically pumped gas lasers and semiconductor frequency multipliers have been studied with these spectrum analyzers and the regimes of these radiation sources were optimized for a single-frequency operation. Future applications of HTSA will be related with quick and precise spectral characterization of new radiation sources and identification of substances in the THz frequency range.

Health State Monitoring of Bladed Machinery with Crack Growth Detection in BFG Power Plant Using an Active Frequency Shift Spectral Correction Method

Directory of Open Access Journals (Sweden)

Weifang Sun

2017-08-01

Full Text Available Power generation using waste-gas is an effective and green way to reduce the emission of the harmful blast furnace gas (BFG in pig-iron producing industry. Condition monitoring of mechanical structures in the BFG power plant is of vital importance to guarantee their safety and efficient operations. In this paper, we describe the detection of crack growth of bladed machinery in the BFG power plant via vibration measurement combined with an enhanced spectral correction technique. This technique enables high-precision identification of amplitude, frequency, and phase information (the harmonic information belonging to deterministic harmonic components within the vibration signals. Rather than deriving all harmonic information using neighboring spectral bins in the fast Fourier transform spectrum, this proposed active frequency shift spectral correction method makes use of some interpolated Fourier spectral bins and has a better noise-resisting capacity. We demonstrate that the identified harmonic information via the proposed method is of suppressed numerical error when the same level of noises is presented in the vibration signal, even in comparison with a Hanning-window-based correction method. With the proposed method, we investigated vibration signals collected from a centrifugal compressor. Spectral information of harmonic tones, related to the fundamental working frequency of the centrifugal compressor, is corrected. The extracted spectral information indicates the ongoing development of an impeller blade crack that occurred in the centrifugal compressor. This method proves to be a promising alternative to identify blade cracks at early stages.

Health State Monitoring of Bladed Machinery with Crack Growth Detection in BFG Power Plant Using an Active Frequency Shift Spectral Correction Method.

Science.gov (United States)

Sun, Weifang; Yao, Bin; He, Yuchao; Chen, Binqiang; Zeng, Nianyin; He, Wangpeng

2017-08-09

Power generation using waste-gas is an effective and green way to reduce the emission of the harmful blast furnace gas (BFG) in pig-iron producing industry. Condition monitoring of mechanical structures in the BFG power plant is of vital importance to guarantee their safety and efficient operations. In this paper, we describe the detection of crack growth of bladed machinery in the BFG power plant via vibration measurement combined with an enhanced spectral correction technique. This technique enables high-precision identification of amplitude, frequency, and phase information (the harmonic information) belonging to deterministic harmonic components within the vibration signals. Rather than deriving all harmonic information using neighboring spectral bins in the fast Fourier transform spectrum, this proposed active frequency shift spectral correction method makes use of some interpolated Fourier spectral bins and has a better noise-resisting capacity. We demonstrate that the identified harmonic information via the proposed method is of suppressed numerical error when the same level of noises is presented in the vibration signal, even in comparison with a Hanning-window-based correction method. With the proposed method, we investigated vibration signals collected from a centrifugal compressor. Spectral information of harmonic tones, related to the fundamental working frequency of the centrifugal compressor, is corrected. The extracted spectral information indicates the ongoing development of an impeller blade crack that occurred in the centrifugal compressor. This method proves to be a promising alternative to identify blade cracks at early stages.

Antepartum Fetal Monitoring and Spectral Analysis of Preterm Birth Risk

Science.gov (United States)

Păsăricără, Alexandru; Nemescu, Dragoş; Arotăriţei, Dragoş; Rotariu, Cristian

2017-11-01

The monitoring and analysis of antepartum fetal and maternal recordings is a research area of notable interest due to the relatively high value of preterm birth. The interest stems from the improvement of devices used for monitoring. The current paper presents the spectral analysis of antepartum heart rate recordings conducted during a study in Romania at the Cuza Voda Obstetrics and Gynecology Clinical Hospital from Iasi between 2010 and 2014. The study focuses on normal and preterm birth risk subjects in order to determine differences between these two types or recordings in terms of spectral analysis.

Model reduction and analysis of a vibrating beam microgyroscope

KAUST Repository

Ghommem, Mehdi; Nayfeh, Ali Hasan; Choura, Slim A.

2012-01-01

The present work is concerned with the nonlinear dynamic analysis of a vibrating beam microgyroscope composed of a rotating cantilever beam with a tip mass at its end. The rigid mass is coupled to two orthogonal electrodes in the drive and sense directions, which are attached to the rotating base. The microbeam is driven by an AC voltage in the drive direction, which induces vibrations in the orthogonal sense direction due to rotation about the microbeam axis. The electrode placed in the sense direction is used to measure the induced motions and extract the underlying angular speed. A reduced-order model of the gyroscope is developed using the method of multiple scales and used to examine its dynamic behavior. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Model reduction and analysis of a vibrating beam microgyroscope

KAUST Repository

Ghommem, Mehdi

2012-05-08

The present work is concerned with the nonlinear dynamic analysis of a vibrating beam microgyroscope composed of a rotating cantilever beam with a tip mass at its end. The rigid mass is coupled to two orthogonal electrodes in the drive and sense directions, which are attached to the rotating base. The microbeam is driven by an AC voltage in the drive direction, which induces vibrations in the orthogonal sense direction due to rotation about the microbeam axis. The electrode placed in the sense direction is used to measure the induced motions and extract the underlying angular speed. A reduced-order model of the gyroscope is developed using the method of multiple scales and used to examine its dynamic behavior. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Use of the local-global concept in detecting component vibration in reactors

International Nuclear Information System (INIS)

Al-Ammar, M.A.

1981-01-01

The local-global concept, based on the detector adjoint function, was used to develop the response of a detector to an absorber vibrating in one dimension. A one-dimensional two-group diffusion code was developed to calculate the frequency dependent detector response as a function of detector and absorber positions for the coupled-core UTR-10 reactor. Results from this code indicated the best possible detector and absorber locations, where more detailed calculations were made using a two-group, three-dimensional diffusion code with finite detector and absorber volumes. An experiment was then designed, for the chosen positions, using a vibrating cadmium absorber with a detector on each side. The assembly was placed in the vertical central stringer of the reactor. Investigations were carried out for vibrations in two flux gradients and experimental data were analyzed in the frequency domain using a microcomputer-based data acquisition system. The experimental investigation showed the validity of the local-global concept. A normalized outputs cross power spectral density was developed that correctly predicted the different flux tilts in the two flux gradients. It was also shown that the frequency response of the local component had a wide plateau region. Monitoring the behavior of the normalized cross power spectral density was thought to be a promising indicator for the detection and localization of malfunctioning vibrating components. It might also be used to detect flux irregularities in the vicinity of a vibrating component

Wave propagation of spectral energy content in a granular chain

NARCIS (Netherlands)

Shrivastava, Rohit Kumar; Luding, Stefan

2017-01-01

A mechanical wave is propagation of vibration with transfer of energy and momentum. Understanding the spectral energy characteristics of a propagating wave through disordered granular media can assist in understanding the overall properties of wave propagation through inhomogeneous materials like

Advanced Engine Health Management Applications of the SSME Real-Time Vibration Monitoring System

Science.gov (United States)

Fiorucci, Tony R.; Lakin, David R., II; Reynolds, Tracy D.; Turner, James E. (Technical Monitor)

2000-01-01

The Real Time Vibration Monitoring System (RTVMS) is a 32-channel high speed vibration data acquisition and processing system developed at Marshall Space Flight Center (MSFC). It Delivers sample rates as high as 51,200 samples/second per channel and performs Fast Fourier Transform (FFT) processing via on-board digital signal processing (DSP) chips in a real-time format. Advanced engine health assessment is achieved by utilizing the vibration spectra to provide accurate sensor validation and enhanced engine vibration redlines. Discrete spectral signatures (such as synchronous) that are indicators of imminent failure can be assessed and utilized to mitigate catastrophic engine failures- a first in rocket engine health assessment. This paper is presented in viewgraph form.

Analysis of different vibration patterns to guide blind people.

Science.gov (United States)

Durá-Gil, Juan V; Bazuelo-Ruiz, Bruno; Moro-Pérez, David; Mollà-Domenech, Fernando

2017-01-01

The literature indicates the best vibration positions and frequencies on the human body where tactile information is transmitted. However, there is a lack of knowledge about how to combine tactile stimuli for navigation. The aim of this study is to compare different vibration patterns outputted to blind people and to determine the most intuitive vibration patterns to indicate direction for navigation purposes through a tactile belt. The vibration patterns that stimulate the front side of the waist are preferred for indicating direction. Vibration patterns applied on the back side of the waist could be suitable for sending messages such as stop.

Berkeley SuperNova Ia Program (BSNIP): Initial Spectral Analysis

Science.gov (United States)

Silverman, Jeffrey; Kong, J.; Ganeshalingam, M.; Li, W.; Filippenko, A. V.

2011-01-01

The Berkeley SuperNova Ia Program (BSNIP) has been observing nearby (z analysis of this dataset consists of accurately and robustly measuring the strength and position of various spectral features near maximum brightness. We determine the endpoints, pseudo-continuum, expansion velocity, equivalent width, and depth of each major feature observed in our wavelength range. For objects with multiple spectra near maximum brightness we investigate how these values change with time. From these measurements we also calculate velocity gradients and various flux ratios within a given spectrum which will allow us to explore correlations between spectral and photometric observables. Some possible correlations have been studied previously, but our dataset is unique in how self-consistent the data reduction and spectral feature measurements have been, and it is a factor of a few larger than most earlier studies. We will briefly summarize the contents of the full dataset as an introduction to our initial analysis. Some of our measurements of SN Ia spectral features, along with a few initial results from those measurements, will be presented. Finally, we will comment on our current progress and planned future work. We gratefully acknowledge the financial support of NSF grant AST-0908886, the TABASGO Foundation, and the Marc J. Staley Graduate Fellowship in Astronomy.

Optimised Spectral Kurtosis for bearing diagnostics under electromagnetic interference

Science.gov (United States)

Smith, Wade A.; Fan, Zhiqi; Peng, Zhongxiao; Li, Huaizhong; Randall, Robert B.

2016-06-01

The selection of the optimal demodulation frequency band is a significant step in bearing fault diagnosis because it determines whether the fault information can be extracted from the demodulated signal via envelope analysis. Two well-known methods for selecting the demodulation band are the Fast Kurtogram, based on the kurtosis of the filtered time signal, and the Protrugram, which uses the kurtosis of the envelope (amplitude) spectrum. Although these two methods have been successfully applied in many cases, the authors have observed that they may fail in specific environments, such as in the presence of electromagnetic interference (EMI) or other impulsive masking signals. In this paper, a simple spectral kurtosis-based approach is proposed for selecting the best demodulation band to extract bearing fault-related impulsive content from vibration signals contaminated with strong EMI. The method is applied to vibration signals obtained from a planetary gearbox test rig with planet bearings seeded with inner and outer race faults. Results from the Fast Kurtogram and Protrugram methods are also included for comparison. The proposed approach is found to exhibit superior diagnostic performance in the presence of intense EMI. Another contribution of the paper is to introduce and explain the issue of EMI to the condition monitoring community. The paper outlines the characteristics of EMI arising from widely-used variable frequency drives, and these characteristics are used to simulate an EMI-contaminated vibration signal to further test the performance of the proposed approach. Although EMI has been acknowledged as a serious problem in many industrial cases, there have been very few studies showing its adverse effects on machine diagnostics. It is important for analysts to be able to identify EMI in measured vibration signals, lest it interfere with the analysis undertaken.

Control method for multi-input multi-output non-Gaussian random vibration test with cross spectra consideration

Directory of Open Access Journals (Sweden)

Ronghui ZHENG

2017-12-01

Full Text Available A control method for Multi-Input Multi-Output (MIMO non-Gaussian random vibration test with cross spectra consideration is proposed in the paper. The aim of the proposed control method is to replicate the specified references composed of auto spectral densities, cross spectral densities and kurtoses on the test article in the laboratory. It is found that the cross spectral densities will bring intractable coupling problems and induce difficulty for the control of the multi-output kurtoses. Hence, a sequential phase modification method is put forward to solve the coupling problems in multi-input multi-output non-Gaussian random vibration test. To achieve the specified responses, an improved zero memory nonlinear transformation is utilized first to modify the Fourier phases of the signals with sequential phase modification method to obtain one frame reference response signals which satisfy the reference spectra and reference kurtoses. Then, an inverse system method is used in frequency domain to obtain the continuous stationary drive signals. At the same time, the matrix power control algorithm is utilized to control the spectra and kurtoses of the response signals further. At the end of the paper, a simulation example with a cantilever beam and a vibration shaker test are implemented and the results support the proposed method very well. Keywords: Cross spectra, Kurtosis control, Multi-input multi-output, Non-Gaussian, Random vibration test

Resonance tunneling electron-vibrational spectroscopy of polyoxometalates.

Science.gov (United States)

Dalidchik, F I; Kovalevskii, S A; Balashov, E M

2017-05-21

The tunneling spectra of the ordered monolayer films of decamolybdodicobaltate (DMDC) compounds deposited from aqueous solutions on HOPG were measured by scanning tunnel microscopy in air. The DMDC spectra, as well as the tunneling spectra of other polyoxometalates (POMs), exhibit well-defined negative differential resistances (NDRs). The mechanism of formation of these spectral features was established from the collection of revealed NDR dependences on the external varying parameters and found to be common to all systems exhibiting Wannier-Stark localization. A model of biresonance tunneling was developed to provide an explanation for the totality of experimental data, both the literature and original, on the tunneling POM probing. A variant of the tunneling electron-vibrational POM spectroscopy was proposed allowing the determination of the three basic energy parameters-energy gaps between the occupied and unoccupied states, frequencies of the vibrational transitions accompanying biresonance electron-tunneling processes, and electron-vibrational interaction constants on the monomolecular level.

Vibrational spectroscopic studies of Isoleucine by quantum chemical calculations.

Science.gov (United States)

Moorthi, P P; Gunasekaran, S; Ramkumaar, G R

2014-04-24

In this work, we reported a combined experimental and theoretical study on molecular structure, vibrational spectra and NBO analysis of Isoleucine (2-Amino-3-methylpentanoic acid). The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments, thermodynamics properties, NBO analyses, NMR chemical shifts and ultraviolet-visible spectral interpretation of Isoleucine have been studied by performing MP2 and DFT/cc-pVDZ level of theory. The FTIR, FT-Raman spectra were recorded in the region 4000-400 cm(-1) and 3500-50 cm(-1) respectively. The UV-visible absorption spectra of the compound were recorded in the range of 200-800 nm. Computational calculations at MP2 and B3LYP level with basis set of cc-pVDZ is employed in complete assignments of Isoleucine molecule on the basis of the potential energy distribution (PED) of the vibrational modes, calculated using VEDA-4 program. The calculated wavenumbers are compared with the experimental values. The difference between the observed and calculated wavenumber values of most of the fundamentals is very small. (13)C and (1)H nuclear magnetic resonance chemical shifts of the molecule were calculated using the gauge independent atomic orbital (GIAO) method and compared with experimental results. The formation of hydrogen bond was investigated in terms of the charge density by the NBO calculations. Based on the UV spectra and TD-DFT calculations, the electronic structure and the assignments of the absorption bands were carried out. Besides, molecular electrostatic potential (MEP) were investigated using theoretical calculations. Copyright © 2014 Elsevier B.V. All rights reserved.

Simplified analysis method for vibration of fusion reactor components with magnetic damping

International Nuclear Information System (INIS)

Tanaka, Yoshikazu; Horie, Tomoyoshi; Niho, Tomoya

2000-01-01

This paper describes two simplified analysis methods for the magnetically damped vibration. One is the method modifying the result of finite element uncoupled analysis using the coupling intensity parameter, and the other is the method using the solution and coupled eigenvalues of the single-degree-of-freedom coupled model. To verify these methods, numerical analyses of a plate and a thin cylinder are performed. The comparison between the results of the former method and the finite element tightly coupled analysis show almost satisfactory agreement. The results of the latter method agree very well with the finite element tightly coupled results because of the coupled eigenvalues. Since the vibration with magnetic damping can be evaluated using these methods without finite element coupled analysis, these approximate methods will be practical and useful for the wide range of design analyses taking account of the magnetic damping effect

Analysis of flow-induced vibration of heat exchanger and steam generator tube bundles using the AECL computer code PIPEAU-2

International Nuclear Information System (INIS)

Gorman, D.J.

1983-12-01

PIPEAU-2 is a computer code developed at the Chalk River Nuclear Laboratories for the flow-induced vibration analysis of heat exchanger and steam generator tube bundles. It can perform this analysis for straight and 'U' tubes. All the theoretical work underlying the code is analytical rather than numerical in nature. Highly accurate evaluation of the free vibration frequencies and mode shapes is therefore obtained. Using the latest experimentally determined parameters available, the free vibration analysis is followed by a forced vibration analysis. Tube response due to fluid turbulence and vortex shedding is determined, as well as critical fluid velocity associated with fluid-elastic instability

Nonlinear dynamic analysis of 2-DOF nonlinear vibration isolation floating raft systems with feedback control

International Nuclear Information System (INIS)

Li Yingli; Xu Daolin; Fu Yiming; Zhou Jiaxi

2012-01-01

In this paper, the average method is adopted to analysis dynamic characteristics of nonlinear vibration isolation floating raft system with feedback control. The analytic results show that the purposes of reducing amplitude of oscillation and complicating the motion can be achieved by adjusting properly the system parameters, exciting frequency and control gain. The conclusions can provide some available evidences for the design and improvement of both the passive and active control of the vibration isolation systems. By altering the exciting frequency and control gain, complex motion of the system can be obtained. Numerical simulations show the system exhibits period vibration, double period vibration and quasi-period motion.

The approximation function of bridge deck vibration derived from the measured eigenmodes

Directory of Open Access Journals (Sweden)

Sokol Milan

2017-12-01

Full Text Available This article deals with a method of how to acquire approximate displacement vibration functions. Input values are discrete, experimentally obtained mode shapes. A new improved approximation method based on the modal vibrations of the deck is derived using the least-squares method. An alternative approach to be employed in this paper is to approximate the displacement vibration function by a sum of sine functions whose periodicity is determined by spectral analysis adapted for non-uniformly sampled data and where the parameters of scale and phase are estimated as usual by the least-squares method. Moreover, this periodic component is supplemented by a cubic regression spline (fitted on its residuals that captures individual displacements between piers. The statistical evaluation of the stiffness parameter is performed using more vertical modes obtained from experimental results. The previous method (Sokol and Flesch, 2005, which was derived for near the pier areas, has been enhanced to the whole length of the bridge. The experimental data describing the mode shapes are not appropriate for direct use. Especially the higher derivatives calculated from these data are very sensitive to data precision.

Automatic Condition Monitoring of Industrial Rolling-Element Bearings Using Motor’s Vibration and Current Analysis

DEFF Research Database (Denmark)

Yang, Zhenyu

2015-01-01

An automatic condition monitoring for a class of industrial rolling-element bearings is developed based on the vibration as well as stator current analysis. The considered fault scenarios include a single-point defect, multiple-point defects, and a type of distributed defect. Motivated by the pot...... characteristic frequencies, sideband effects, time-average of spectra, and selection of fault index and thresholds, are also discussed. The experimental work shows a huge potential to use some simple methods for successful diagnosis of industrial bearing systems.......An automatic condition monitoring for a class of industrial rolling-element bearings is developed based on the vibration as well as stator current analysis. The considered fault scenarios include a single-point defect, multiple-point defects, and a type of distributed defect. Motivated...... is extensively studied under diverse operating conditions: different sensor locations, motor speeds, loading conditions, and data samples from different time segments. The experimental results showed the powerful capability of vibration analysis in the bearing point defect fault diagnosis. The current analysis...

Editorial: Special Issue on Experimental Vibration Analysis

Science.gov (United States)

Serra, Roger

2018-04-01

The vibratory analyses are particularly present today in the various fields of industry, from aeronautics to manufacturing, from machining and maintenance to civil engineering, to mention a few areas, which have made this special issue a true need. The International Journal of Mechanics & Industry compiles a Special Issue on Experimental Vibration Analysis. More than thirty manuscripts were received by the international scientific committee on the 6th congress AVE2016 and only eight papers have been selected after completing a careful and rigorous peer-review process for the Special Issue, which are briefly summarized below.

Computational Fluid Dynamic Analysis of a Vibrating Turbine Blade

Directory of Open Access Journals (Sweden)

Osama N. Alshroof

2012-01-01

Full Text Available This study presents the numerical fluid-structure interaction (FSI modelling of a vibrating turbine blade using the commercial software ANSYS-12.1. The study has two major aims: (i discussion of the current state of the art of modelling FSI in gas turbine engines and (ii development of a “tuned” one-way FSI model of a vibrating turbine blade to investigate the correlation between the pressure at the turbine casing surface and the vibrating blade motion. Firstly, the feasibility of the complete FSI coupled two-way, three-dimensional modelling of a turbine blade undergoing vibration using current commercial software is discussed. Various modelling simplifications, which reduce the full coupling between the fluid and structural domains, are then presented. The one-way FSI model of the vibrating turbine blade is introduced, which has the computational efficiency of a moving boundary CFD model. This one-way FSI model includes the corrected motion of the vibrating turbine blade under given engine flow conditions. This one-way FSI model is used to interrogate the pressure around a vibrating gas turbine blade. The results obtained show that the pressure distribution at the casing surface does not differ significantly, in its general form, from the pressure at the vibrating rotor blade tip.

Fault feature extraction of planet gear in wind turbine gearbox based on spectral kurtosis and time wavelet energy spectrum

Science.gov (United States)

Kong, Yun; Wang, Tianyang; Li, Zheng; Chu, Fulei

2017-09-01

Planetary transmission plays a vital role in wind turbine drivetrains, and its fault diagnosis has been an important and challenging issue. Owing to the complicated and coupled vibration source, time-variant vibration transfer path, and heavy background noise masking effect, the vibration signal of planet gear in wind turbine gearboxes exhibits several unique characteristics: Complex frequency components, low signal-to-noise ratio, and weak fault feature. In this sense, the periodic impulsive components induced by a localized defect are hard to extract, and the fault detection of planet gear in wind turbines remains to be a challenging research work. Aiming to extract the fault feature of planet gear effectively, we propose a novel feature extraction method based on spectral kurtosis and time wavelet energy spectrum (SK-TWES) in the paper. Firstly, the spectral kurtosis (SK) and kurtogram of raw vibration signals are computed and exploited to select the optimal filtering parameter for the subsequent band-pass filtering. Then, the band-pass filtering is applied to extrude periodic transient impulses using the optimal frequency band in which the corresponding SK value is maximal. Finally, the time wavelet energy spectrum analysis is performed on the filtered signal, selecting Morlet wavelet as the mother wavelet which possesses a high similarity to the impulsive components. The experimental signals collected from the wind turbine gearbox test rig demonstrate that the proposed method is effective at the feature extraction and fault diagnosis for the planet gear with a localized defect.

Analysis of the phenomena associated with structural damage using real time vibration analysis

International Nuclear Information System (INIS)

Garcia Peyrano, O; Cismondi, L; Damiani, H; Torres, E

2004-01-01

It is of interest to have analytical methodologies available for the dynamic behavior of large mechanical structures like those in thermal cycle systems of nuclear power plants or in transport systems during the experimental stage prior to their construction, as happens in aeronautics, where prototypes are tested in experimental banks on a scale of 1 to 1. The same does not occur with systems for the generation of electrical energy such as a nuclear power plant or in ships, competition automobiles, railway systems, etc. Not because of the technical impossibility but because of the high costs involved. This work aims to implement a technology based on the analysis of the vibrations to obtain a profile of the modal dynamic response and its influence on the critical components of the mechanisms with the particularity of detecting the preventive location of the component that may suffer a potential damage. The Vibrations Analysis Laboratory has resolved different cases in the Embalse Nuclear Plant, in the Atucha Nuclear Plant, in the Heavy Water Industrial Plant, in the automobile industry and in other industrial areas (CW)

Analysis of different vibration patterns to guide blind people

Directory of Open Access Journals (Sweden)

Juan V. Durá-Gil

2017-03-01

Full Text Available The literature indicates the best vibration positions and frequencies on the human body where tactile information is transmitted. However, there is a lack of knowledge about how to combine tactile stimuli for navigation. The aim of this study is to compare different vibration patterns outputted to blind people and to determine the most intuitive vibration patterns to indicate direction for navigation purposes through a tactile belt. The vibration patterns that stimulate the front side of the waist are preferred for indicating direction. Vibration patterns applied on the back side of the waist could be suitable for sending messages such as stop.

Spectral analysis of growing graphs a quantum probability point of view

CERN Document Server

Obata, Nobuaki

2017-01-01

This book is designed as a concise introduction to the recent achievements on spectral analysis of graphs or networks from the point of view of quantum (or non-commutative) probability theory. The main topics are spectral distributions of the adjacency matrices of finite or infinite graphs and their limit distributions for growing graphs. The main vehicle is quantum probability, an algebraic extension of the traditional probability theory, which provides a new framework for the analysis of adjacency matrices revealing their non-commutative nature. For example, the method of quantum decomposition makes it possible to study spectral distributions by means of interacting Fock spaces or equivalently by orthogonal polynomials. Various concepts of independence in quantum probability and corresponding central limit theorems are used for the asymptotic study of spectral distributions for product graphs. This book is written for researchers, teachers, and students interested in graph spectra, their (asymptotic) spectr...

[Applications of spectral analysis technique to monitoring grasshoppers].

Science.gov (United States)

Lu, Hui; Han, Jian-guo; Zhang, Lu-da

2008-12-01

Grasshopper monitoring is of great significance in protecting environment and reducing economic loss. However, how to predict grasshoppers accurately and effectively is a difficult problem for a long time. In the present paper, the importance of forecasting grasshoppers and its habitat is expounded, and the development in monitoring grasshopper populations and the common arithmetic of spectral analysis technique are illustrated. Meanwhile, the traditional methods are compared with the spectral technology. Remote sensing has been applied in monitoring the living, growing and breeding habitats of grasshopper population, and can be used to develop a forecast model combined with GIS. The NDVI values can be analyzed throughout the remote sensing data and be used in grasshopper forecasting. Hyper-spectra remote sensing technique which can be used to monitor grasshoppers more exactly has advantages in measuring the damage degree and classifying damage areas of grasshoppers, so it can be adopted to monitor the spatial distribution dynamic of rangeland grasshopper population. Differentialsmoothing can be used to reflect the relations between the characteristic parameters of hyper-spectra and leaf area index (LAI), and indicate the intensity of grasshopper damage. The technology of near infrared reflectance spectroscopy has been employed in judging grasshopper species, examining species occurrences and monitoring hatching places by measuring humidity and nutrient of soil, and can be used to investigate and observe grasshoppers in sample research. According to this paper, it is concluded that the spectral analysis technique could be used as a quick and exact tool in monitoring and forecasting the infestation of grasshoppers, and will become an important means in such kind of research for their advantages in determining spatial orientation, information extracting and processing. With the rapid development of spectral analysis methodology, the goal of sustainable monitoring

Fault Detection of Reciprocating Compressors using a Model from Principles Component Analysis of Vibrations

International Nuclear Information System (INIS)

Ahmed, M; Gu, F; Ball, A D

2012-01-01

Traditional vibration monitoring techniques have found it difficult to determine a set of effective diagnostic features due to the high complexity of the vibration signals originating from the many different impact sources and wide ranges of practical operating conditions. In this paper Principal Component Analysis (PCA) is used for selecting vibration feature and detecting different faults in a reciprocating compressor. Vibration datasets were collected from the compressor under baseline condition and five common faults: valve leakage, inter-cooler leakage, suction valve leakage, loose drive belt combined with intercooler leakage and belt loose drive belt combined with suction valve leakage. A model using five PCs has been developed using the baseline data sets and the presence of faults can be detected by comparing the T 2 and Q values from the features of fault vibration signals with corresponding thresholds developed from baseline data. However, the Q -statistic procedure produces a better detection as it can separate the five faults completely.

Analysis of rotation-vibration relative equilibria on the example of a tetrahedral four atom molecule

NARCIS (Netherlands)

Efstathiou, K; Sadovskii, DA; Zhilinskii, BI

2004-01-01

We study relative equilibria ( RE) of a nonrigid molecule, which vibrates about a well-defined equilibrium configuration and rotates as a whole. Our analysis unifies the theory of rotational and vibrational RE. We rely on the detailed study of the symmetry group action on the initial and reduced

Vibration analysis of reactor assembly internals for Prototype Fast Breeder Reactor

International Nuclear Information System (INIS)

Chellapandi, P.; Jalaldeen, S.; Srinivasan, R.; Chetal, S.C.; Bhoje, S.B.

2003-01-01

Vibration analysis of the reactor assembly components of 500 MWe Prototype Fast Breeder Reactor (PFBR) is presented. The vibration response of primary pump as well as dynamic forces developed at its supports are predicted numerically. The stiffness properties of hydrostatic bearing are determined by formulating and solving governing fluid and structural mechanics equations. The dynamic forces exerted by pump are used as input data for the dynamic response of reactor assembly components, mainly inner vessel, thermal baffle and control plug. Dynamic response of reactor assembly components is also predicted for the pressure fluctuations caused by sodium free level oscillations. Thermal baffle (weir shell) which is subjected to fluid forces developed at the associated sodium free levels is analysed by formulating and solving a set of non-linear equations for fluids, structures and fluid structure interaction (FSI). The control rod drive mechanism is analysed for response under flow induced forces on the parts subjected to cross flow in the zone just above the core top, taking into account FSI between sheaths of control and safety rod and absorber pin bundle. Based on the analysis results, it is concluded that the reactor assembly internals are free from any risk of mechanical as well as flow induced vibrations. (author)

Spectral analysis of an algebraic collapsing acceleration for the characteristics method

International Nuclear Information System (INIS)

Le Tellier, R.; Hebert, A.

2005-01-01

A spectral analysis of a diffusion synthetic acceleration called Algebraic Collapsing Acceleration (ACA) was carried out in the context of the characteristics method to solve the neutron transport equation. Two analysis were performed in order to assess the ACA performances. Both a standard Fourier analysis in a periodic and infinite slab-geometry and a direct spectral analysis for a finite slab-geometry were investigated. In order to evaluate its performance, ACA was compared with two competing techniques used to accelerate the convergence of the characteristics method, the Self-Collision Re-balancing technique and the Asymptotic Synthetic Acceleration. In the restricted framework of 1-dimensional slab-geometries, we conclude that ACA offers a good compromise between the reduction of the spectral radius of the iterative matrix and the resources to construct, store and solve the corrective system. A comparison on a monoenergetic 2-dimensional benchmark was performed and tends to confirm these conclusions. (authors)

Cloud Masking for Remotely Sensed Data Using Spectral and Principal Components Analysis

Directory of Open Access Journals (Sweden)

A. Ahmad

2012-06-01

Full Text Available Two methods of cloud masking tuned to tropical conditions have been developed, based on spectral analysis and Principal Components Analysis (PCA of Moderate Resolution Imaging Spectroradiometer (MODIS data. In the spectral approach, thresholds were applied to four reflective bands (1, 2, 3, and 4, three thermal bands (29, 31 and 32, the band 2/band 1 ratio, and the difference between band 29 and 31 in order to detect clouds. The PCA approach applied a threshold to the first principal component derived from the seven quantities used for spectral analysis. Cloud detections were compared with the standard MODIS cloud mask, and their accuracy was assessed using reference images and geographical information on the study area.

Force Limited Random Vibration Test of TESS Camera Mass Model

Science.gov (United States)

Karlicek, Alexandra; Hwang, James Ho-Jin; Rey, Justin J.

2015-01-01

The Transiting Exoplanet Survey Satellite (TESS) is a spaceborne instrument consisting of four wide field-of-view-CCD cameras dedicated to the discovery of exoplanets around the brightest stars. As part of the environmental testing campaign, force limiting was used to simulate a realistic random vibration launch environment. While the force limit vibration test method is a standard approach used at multiple institutions including Jet Propulsion Laboratory (JPL), NASA Goddard Space Flight Center (GSFC), European Space Research and Technology Center (ESTEC), and Japan Aerospace Exploration Agency (JAXA), it is still difficult to find an actual implementation process in the literature. This paper describes the step-by-step process on how the force limit method was developed and applied on the TESS camera mass model. The process description includes the design of special fixtures to mount the test article for properly installing force transducers, development of the force spectral density using the semi-empirical method, estimation of the fuzzy factor (C2) based on the mass ratio between the supporting structure and the test article, subsequent validating of the C2 factor during the vibration test, and calculation of the C.G. accelerations using the Root Mean Square (RMS) reaction force in the spectral domain and the peak reaction force in the time domain.

Hardware and software constructs for a vibration analysis network

International Nuclear Information System (INIS)

Cook, S.A.; Crowe, R.D.; Toffer, H.

1985-01-01

Vibration level monitoring and analysis has been initiated at N Reactor, the dual purpose reactor operated at Hanford, Washington by UNC Nuclear Industries (UNC) for the Department of Energy (DOE). The machinery to be monitored was located in several buildings scattered over the plant site, necessitating an approach using satellite stations to collect, monitor and temporarily store data. The satellite stations are, in turn, linked to a centralized processing computer for further analysis. The advantages of a networked data analysis system are discussed in this paper along with the hardware and software required to implement such a system

Automation of vibroacoustic data bank for random vibration criteria development. [for the space shuttle and launch vehicles

Science.gov (United States)

Ferebee, R. C.

1982-01-01

A computerized data bank system was developed for utilization of large amounts of vibration and acoustic data to formulate component random vibration design and test criteria. This system consists of a computer, graphics tablet, and a dry-silver hard copier which are all desk-top type hardware and occupy minimal space. The data bank contains data from the Saturn V and Titan III flight and static test programs. The vibration and acoustic data are stored in the form of power spectral density and one-third octave band plots over the frequency range from 20 to 2000 Hz. The data was stored by digitizing each spectral plot by tracing with the graphics tablet. The digitized data was statistically analyzed and the resulting 97.5% probability levels were stored on tape along with the appropriate structural parameters. Standard extrapolation procedures were programmed for prediction of component random vibration test criteria for new launch vehicle and payload configurations. This automated vibroacoustic data bank system greatly enhances the speed and accuracy of formulating vibration test criteria. In the future, the data bank will be expanded to include all data acquired from the space shuttle flight test program.

Highly vibrationally excited O2 molecules in low-pressure inductively-coupled plasmas detected by high sensitivity ultra-broad-band optical absorption spectroscopy

Science.gov (United States)

Foucher, Mickaël; Marinov, Daniil; Carbone, Emile; Chabert, Pascal; Booth, Jean-Paul

2015-08-01

Inductively-coupled plasmas in pure O2 (at pressures of 5-80 mTorr and radiofrequency power up to 500 W) were studied by optical absorption spectroscopy over the spectral range 200-450 nm, showing the presence of highly vibrationally excited O2 molecules (up to vʺ = 18) by Schumann-Runge band absorption. Analysis of the relative band intensities indicates a vibrational temperature up to 10,000 K, but these hot molecules only represent a fraction of the total O2 density. By analysing the (11-0) band at higher spectral resolution the O2 rotational temperature was also determined, and was found to increase with both pressure and power, reaching 900 K at 80 mTorr 500 W. These measurements were achieved using a new high-sensitivity ultra-broad-band absorption spectroscopy setup, based on a laser-plasma light source, achromatic optics and an aberration-corrected spectrograph. This setup allows the measurement of weak broadband absorbances due to a baseline variability lower than 2   ×   10-5 across a spectral range of 250 nm.

Vibration and Noise in Magnetic Resonance Imaging of the Vocal Tract: Differences between Whole-Body and Open-Air Devices.

Science.gov (United States)

Přibil, Jiří; Přibilová, Anna; Frollo, Ivan

2018-04-05

This article compares open-air and whole-body magnetic resonance imaging (MRI) equipment working with a weak magnetic field as regards the methods of its generation, spectral properties of mechanical vibration and acoustic noise produced by gradient coils during the scanning process, and the measured noise intensity. These devices are used for non-invasive MRI reconstruction of the human vocal tract during phonation with simultaneous speech recording. In this case, the vibration and noise have negative influence on quality of speech signal. Two basic measurement experiments were performed within the paper: mapping sound pressure levels in the MRI device vicinity and picking up vibration and noise signals in the MRI scanning area. Spectral characteristics of these signals are then analyzed statistically and compared visually and numerically.

Analysis of the effect of vibrations on the bentonite buffer in the canister hole

International Nuclear Information System (INIS)

Jonsson, Martin; Hakami, Hossein; Ekneligoda, Thushan

2009-09-01

During the construction of a final repository for spent nuclear fuel in crystalline rock, blasting activities in certain deposition tunnels will occur at the same time as the deposition of canisters containing the waste is going on in another adjacent access tunnel. In fact, the deposition consists of several stages after the drilling of the deposition hole. The most vulnerable stage from a vibration point of view is when the bentonite buffer is placed in the deposition hole but the canister has not been placed yet. During this stage, a hollow column of bentonite blocks remains free to vibrate inside the deposition hole. The goal of this study was to investigate the displacement of the bentonite blocks when exposed to the highest vibration level that can be expected during the drill and blast operations. In order to investigate this, a three dimensional model in 3DEC, capable of capturing the dynamic behaviour of the bentonite buffer was set up. To define the vibration levels, which serve as input data for the 3DEC model, an extensive analysis of the recorded vibrations from the TASQ - tunnel was carried out. For this purpose, an upper expected vibration limit was defined. This was done outgoing from the fact that the planned charging for the construction of the geological repository will lie in the interval 2 to 4 kg. Furthermore, at the first stage for this study, it was decided that the vibration should be conservatively evaluated for 30 m distance. Using these data, it was concluded that the maximum vibration level that can be expected will be approximately 60 mm/s. After simplifying the vibration signal, a sinusoidal wave with the amplitude 60 mm/s was applied at the bottom of the column and it was assumed that the vibrations only affect the bentonite buffer in one direction (horizontal direction). From this simulation, it was concluded that hardly any displacements occurred. However, when applying the same sinusoidal wave both in the horizontal and the

Absolute vibrational numbering from isotope shifts in fragmentary spectroscopic data

Science.gov (United States)

Pashov, A.; Kowalczyk, P.; Jastrzebski, W.

2018-05-01

We discuss application of the isotope effect to establish the absolute vibrational numbering in electronic states of diatomic molecules. This is illustrated by examples of states with potential energy curves of both regular and irregular shape, with one or two potential minima. The minimum number of spectroscopic data (either term values or spectral line positions) necessary to provide a unique numbering is considered. We show that at favourable conditions just four term energies (or spectral lines) in one isotopologue and one term energy in the other suffice.

Analysis of classical guitars' vibrational behavior based on scanning laser vibrometer measurements

Science.gov (United States)

Czajkowska, Marzena

2012-06-01

One of the main goals in musical acoustics research is to link measurable, physical properties of a musical instrument with subjective assessments of its tone quality. The aim of the research discussed in this paper was to observe the structural vibrations of different class classical guitars in relation to their quality. This work focuses on mid-low-and low-class classical (nylon-stringed) guitars. The main source of guitar body vibrations come from top and back plate vibrations therefore these were the objects of structural mode measurements and analysis. Sixteen classical guitars have been investigated, nine with cedar and seven with spruce top plate. Structural modes of top and back plates have been measured with the aid of a scanning laser vibrometer and the instruments were excited with a chirp signal transferred by bone vibrator. The issues related to excitor selection have been discussed. Correlation and descriptive statistics of top and back plates measurement results have been investigated in relation to guitar quality. The frequency range of 300 Hz to 5 kHz as well as selected narrowed frequency bands have been analyzed for cedar and spruce guitars. Furthermore, the influence of top plate wood type on vibration characteristics have been observed on three pairs of guitars. The instruments were of the same model but different top plate material. Determination and visualization of both guitar plates' modal patterns in relation to frequency are a significant attainment of the research. Scanning laser vibrometer measurements allow particular mode observation and therefore mode identification, as opposed to sound pressure response measurements. When correlating vibration characteristics of top and back plates it appears that Pearson productmoment correlation coefficient is not a parameter that associates with guitar quality. However, for best instruments with cedar top, top-back correlation coefficient has relatively greater value in 1-2 kHz band and lower in

[Estimation of Hunan forest carbon density based on spectral mixture analysis of MODIS data].

Science.gov (United States)

Yan, En-ping; Lin, Hui; Wang, Guang-xing; Chen, Zhen-xiong

2015-11-01

With the fast development of remote sensing technology, combining forest inventory sample plot data and remotely sensed images has become a widely used method to map forest carbon density. However, the existence of mixed pixels often impedes the improvement of forest carbon density mapping, especially when low spatial resolution images such as MODIS are used. In this study, MODIS images and national forest inventory sample plot data were used to conduct the study of estimation for forest carbon density. Linear spectral mixture analysis with and without constraint, and nonlinear spectral mixture analysis were compared to derive the fractions of different land use and land cover (LULC) types. Then sequential Gaussian co-simulation algorithm with and without the fraction images from spectral mixture analyses were employed to estimate forest carbon density of Hunan Province. Results showed that 1) Linear spectral mixture analysis with constraint, leading to a mean RMSE of 0.002, more accurately estimated the fractions of LULC types than linear spectral and nonlinear spectral mixture analyses; 2) Integrating spectral mixture analysis model and sequential Gaussian co-simulation algorithm increased the estimation accuracy of forest carbon density to 81.5% from 74.1%, and decreased the RMSE to 5.18 from 7.26; and 3) The mean value of forest carbon density for the province was 30.06 t · hm(-2), ranging from 0.00 to 67.35 t · hm(-2). This implied that the spectral mixture analysis provided a great potential to increase the estimation accuracy of forest carbon density on regional and global level.

The Shock and Vibration Bulletin. Part 2. Vibration Analysis.

Science.gov (United States)

1977-09-01

J.N. Tait, Naval Air Development Center, Warminster, PA EVALUATION OF AN ADAPTIVE FILTER AS A DIGITAL TRACKING FILTER D.O. Smallwood and D.L. Gregory...Oklahoma Norman , Oklahoma In contrast to the considerable information abailable on free vibration of isotropic plates, there is only a very limited

Vibrations and Stability: Solved Problems

DEFF Research Database (Denmark)

Thomsen, Jon Juel

Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003.......Worked out solutions for exercise problems in J. J. Thomsen 'Vibrations and Stability: Advanced Theory, Analysis, and Tools', Springer, Berlin - Heidelberg, 2003....

Outlier Detection with Space Transformation and Spectral Analysis

DEFF Research Database (Denmark)

Dang, Xuan-Hong; Micenková, Barbora; Assent, Ira

2013-01-01

which rely on notions of distances or densities, this approach introduces a novel concept based on local quadratic entropy for evaluating the similarity of a data object with its neighbors. This information theoretic quantity is used to regularize the closeness amongst data instances and subsequently......Detecting a small number of outliers from a set of data observations is always challenging. In this paper, we present an approach that exploits space transformation and uses spectral analysis in the newly transformed space for outlier detection. Unlike most existing techniques in the literature...... benefits the process of mapping data into a usually lower dimensional space. Outliers are then identified by spectral analysis of the eigenspace spanned by the set of leading eigenvectors derived from the mapping procedure. The proposed technique is purely data-driven and imposes no assumptions regarding...

Advanced non-linear flow-induced vibration and fretting-wear analysis capabilities

Energy Technology Data Exchange (ETDEWEB)

Toorani, M.; Pan, L.; Li, R.; Idvorian, N. [Babcock and Wilcox Canada Ltd., Cambridge, Ontario (Canada); Vincent, B.

2009-07-01

Fretting wear is a potentially significant degradation mechanism in nuclear steam generators and other shell and tube heat transfer equipment as well. This paper presents an overview of the recently developed code FIVDYNA which is used for the non-linear flow-induced vibration and fretting wear analysis for operating steam generators (OTSG and RSG) and shell-and-tube heat exchangers. FIVDYNA is a non-linear time-history Flow-Induced Vibration (FIV) analysis computer program that has been developed by Babcock and Wilcox Canada to advance the understanding of tube vibration and tube to tube-support interaction. In addition to the dynamic fluid induced forces the program takes into account other tube static forces due to axial and lateral tube preload and thermal interaction loads. The program is capable of predicting the location where the fretting wear is most likely to occur and its magnitude taking into account the support geometry including gaps. FIVDYNA uses the general purpose finite element computer code ABAQUS as its solver. Using ABAQUS gives the user the flexibility to add additional forces to the tube ranging from tube preloads and the support offsets to thermal loads. The forces currently being modeled in FIVDYNA are the random turbulence, steady drag force, fluid-elastic forces, support offset and pre-strain force (axial loads). This program models the vibration of tubes and calculates the structural dynamic characteristics, and interaction forces between the tube and the tube supports. These interaction forces are then used to calculate the work rate at the support and eventually the predicted depth of wear scar on the tube. A very good agreement is found with experiments and also other computer codes. (author)

PC based vibration monitoring system

International Nuclear Information System (INIS)

Jain, Sanjay K.; Roy, D.A.; Pithawa, C.K.; Patil, R.K.

2004-01-01

Health of large rotating machinery gets reflected in the vibration signature of the rotor and supporting structures and proper recording of these signals and their analysis can give a clear picture of the health of the machine. Using these data and their trending, it is possible to predict an impending trouble in the machine so that preventive action can be taken in time and catastrophic failure can be avoided. Continuous monitoring and analysis can give quick warning and enable operator to take preventive measures. Reactor Control Division, BARC is developing a PC based Vibration monitoring system for turbo generator machinery. The System can acquire 20 vibration signals at a rate of 5000 samples per second and also 15 process signals at a rate of 100 samples/ sec. The software for vibration monitoring system includes acquisition modules, analysis modules and Graphical User Interface module. The acquisition module involves initialization, setting of required parameters and acquiring the data from PC-based data acquisition cards. The acquired raw vibration data is then stored for analysis using various software packages. The display and analysis of acquired data is done in LabVIEW 7.0 where the data is displayed in time as well as frequency domain along with the RMS value of the signal. (author)

Advanced Vibration Analysis Tool Developed for Robust Engine Rotor Designs

Science.gov (United States)

Min, James B.

2005-01-01

The primary objective of this research program is to develop vibration analysis tools, design tools, and design strategies to significantly improve the safety and robustness of turbine engine rotors. Bladed disks in turbine engines always feature small, random blade-to-blade differences, or mistuning. Mistuning can lead to a dramatic increase in blade forced-response amplitudes and stresses. Ultimately, this results in high-cycle fatigue, which is a major safety and cost concern. In this research program, the necessary steps will be taken to transform a state-of-the-art vibration analysis tool, the Turbo- Reduce forced-response prediction code, into an effective design tool by enhancing and extending the underlying modeling and analysis methods. Furthermore, novel techniques will be developed to assess the safety of a given design. In particular, a procedure will be established for using natural-frequency curve veerings to identify ranges of operating conditions (rotational speeds and engine orders) in which there is a great risk that the rotor blades will suffer high stresses. This work also will aid statistical studies of the forced response by reducing the necessary number of simulations. Finally, new strategies for improving the design of rotors will be pursued.

Study of vibration analysis for nuclear reactor building

International Nuclear Information System (INIS)

Hirashima, Shin-ichi

1978-01-01

The mutual interference between the contiguous buildings with separate foundations and also that between the outer wall under the ground and the foundation bottom of the building were taken into consideration for the vibration analysis with spring-mass system. For two contiguous foundations of buildings it was attempted to represent the static mutual interference by a spring-mass system model. The theoretical analysis formulas are shown for the combination of the vertical movement and rocking motion, and for the interfering forces between the foundation and the outer wall of a building. The method of extending the model to dynamic one is explained. Several spring constants utilized in the analysis were obtained, for example, for mutual interference springs regarding vertical motion, mutual interfering springs for the foundation and the outer wall of a building and the mutual interference springs concerning horizontal movement. These models and analysis were applied to the BWR-MARK II-1100 MW nuclear reactor building and the contiguous turbine building. The structures and level relations of two buildings are shown, and the spring-mass system model for these buildings is expressed. The masses of about 20, the weights, the rotating inertia, the sectional moment of inertia, the spring constant and the damping coefficient for each mass are tabulated. As the results, the peak displacements occur at 2.556 Hz, 6.918 Hz, 10.43 Hz and 13.85 Hz. The damping coefficient is large and about 10 - 30% at the lower order modes. The calculated and the measured vibration characteristics for the BWR plant buildings are not much different, and this spring-mass system model is verified to be adequate. (Nakai, Y.)

Monte-Carlo error analysis in x-ray spectral deconvolution

International Nuclear Information System (INIS)

Shirk, D.G.; Hoffman, N.M.

1985-01-01

The deconvolution of spectral information from sparse x-ray data is a widely encountered problem in data analysis. An often-neglected aspect of this problem is the propagation of random error in the deconvolution process. We have developed a Monte-Carlo approach that enables us to attach error bars to unfolded x-ray spectra. Our Monte-Carlo error analysis has been incorporated into two specific deconvolution techniques: the first is an iterative convergent weight method; the second is a singular-value-decomposition (SVD) method. These two methods were applied to an x-ray spectral deconvolution problem having m channels of observations with n points in energy space. When m is less than n, this problem has no unique solution. We discuss the systematics of nonunique solutions and energy-dependent error bars for both methods. The Monte-Carlo approach has a particular benefit in relation to the SVD method: It allows us to apply the constraint of spectral nonnegativity after the SVD deconvolution rather than before. Consequently, we can identify inconsistencies between different detector channels

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.

An adaptive demodulation approach for bearing fault detection based on adaptive wavelet filtering and spectral subtraction

Science.gov (United States)

Zhang, Yan; Tang, Baoping; Liu, Ziran; Chen, Rengxiang

2016-02-01

Fault diagnosis of rolling element bearings is important for improving mechanical system reliability and performance. Vibration signals contain a wealth of complex information useful for state monitoring and fault diagnosis. However, any fault-related impulses in the original signal are often severely tainted by various noises and the interfering vibrations caused by other machine elements. Narrow-band amplitude demodulation has been an effective technique to detect bearing faults by identifying bearing fault characteristic frequencies. To achieve this, the key step is to remove the corrupting noise and interference, and to enhance the weak signatures of the bearing fault. In this paper, a new method based on adaptive wavelet filtering and spectral subtraction is proposed for fault diagnosis in bearings. First, to eliminate the frequency associated with interfering vibrations, the vibration signal is bandpass filtered with a Morlet wavelet filter whose parameters (i.e. center frequency and bandwidth) are selected in separate steps. An alternative and efficient method of determining the center frequency is proposed that utilizes the statistical information contained in the production functions (PFs). The bandwidth parameter is optimized using a local ‘greedy’ scheme along with Shannon wavelet entropy criterion. Then, to further reduce the residual in-band noise in the filtered signal, a spectral subtraction procedure is elaborated after wavelet filtering. Instead of resorting to a reference signal as in the majority of papers in the literature, the new method estimates the power spectral density of the in-band noise from the associated PF. The effectiveness of the proposed method is validated using simulated data, test rig data, and vibration data recorded from the transmission system of a helicopter. The experimental results and comparisons with other methods indicate that the proposed method is an effective approach to detecting the fault-related impulses

An adaptive demodulation approach for bearing fault detection based on adaptive wavelet filtering and spectral subtraction

International Nuclear Information System (INIS)

Zhang, Yan; Tang, Baoping; Chen, Rengxiang; Liu, Ziran

2016-01-01

Fault diagnosis of rolling element bearings is important for improving mechanical system reliability and performance. Vibration signals contain a wealth of complex information useful for state monitoring and fault diagnosis. However, any fault-related impulses in the original signal are often severely tainted by various noises and the interfering vibrations caused by other machine elements. Narrow-band amplitude demodulation has been an effective technique to detect bearing faults by identifying bearing fault characteristic frequencies. To achieve this, the key step is to remove the corrupting noise and interference, and to enhance the weak signatures of the bearing fault. In this paper, a new method based on adaptive wavelet filtering and spectral subtraction is proposed for fault diagnosis in bearings. First, to eliminate the frequency associated with interfering vibrations, the vibration signal is bandpass filtered with a Morlet wavelet filter whose parameters (i.e. center frequency and bandwidth) are selected in separate steps. An alternative and efficient method of determining the center frequency is proposed that utilizes the statistical information contained in the production functions (PFs). The bandwidth parameter is optimized using a local ‘greedy’ scheme along with Shannon wavelet entropy criterion. Then, to further reduce the residual in-band noise in the filtered signal, a spectral subtraction procedure is elaborated after wavelet filtering. Instead of resorting to a reference signal as in the majority of papers in the literature, the new method estimates the power spectral density of the in-band noise from the associated PF. The effectiveness of the proposed method is validated using simulated data, test rig data, and vibration data recorded from the transmission system of a helicopter. The experimental results and comparisons with other methods indicate that the proposed method is an effective approach to detecting the fault-related impulses

Spectral analysis of the structure of ultradispersed diamonds

Science.gov (United States)

Uglov, V. V.; Shimanski, V. I.; Rusalsky, D. P.; Samtsov, M. P.

2008-07-01

The structure of ultradispersed diamonds (UDD) is studied by spectral methods. The presence of diamond crystal phase in the UDD is found based on x-ray analysis and Raman spectra. The Raman spectra also show sp2-and sp3-hybridized carbon. Analysis of IR absorption spectra suggests that the composition of functional groups present in the particles changes during the treatment.

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

Influence of intermolecular amide hydrogen bonding on the geometry, atomic charges, and spectral modes of acetanilide: An ab initio study

Science.gov (United States)

Binoy, J.; Prathima, N. B.; Murali Krishna, C.; Santhosh, C.; Hubert Joe, I.; Jayakumar, V. S.

2006-08-01

Acetanilide, a compound of pharmaceutical importance possessing pain-relieving properties due to its blocking the pulse dissipating along the nerve fiber, is subjected to vibrational spectral investigation using NIR FT Raman, FT-IR, and SERS. The geometry, Mulliken charges, and vibrational spectrum of acetanilide have been computed using the Hartree-Fock theory and density functional theory employing the 6-31G (d) basis set. To investigate the influence of intermolecular amide hydrogen bonding, the geometry, charge distribution, and vibrational spectrum of the acetanilide dimer have been computed at the HF/6-31G (d) level. The computed geometries reveal that the acetanilide molecule is planar, while twisting of the secondary amide group with respect to the phenyl ring is found upon hydrogen bonding. The trans isomerism and “amido” form of the secondary amide, hyperconjugation of the C=O group with the adjacent C-C bond, and donor-acceptor interaction have been investigated using computed geometry. The carbonyl stretching band position is found to be influenced by the tendency of the phenyl ring to withdraw nitrogen lone pair, intermolecular hydrogen bonding, conjugation, and hyperconjugation. A decrease in the NH and C=O bond orders and increase in the C-N bond orders due to donor-acceptor interaction can be observed in the vibrational spectra. The SERS spectral analysis reveals that the flat orientation of the molecule on the adsorption plane is preferred.

Statistical Analysis of Spectral Properties and Prosodic Parameters of Emotional Speech

Science.gov (United States)

Přibil, J.; Přibilová, A.

2009-01-01

The paper addresses reflection of microintonation and spectral properties in male and female acted emotional speech. Microintonation component of speech melody is analyzed regarding its spectral and statistical parameters. According to psychological research of emotional speech, different emotions are accompanied by different spectral noise. We control its amount by spectral flatness according to which the high frequency noise is mixed in voiced frames during cepstral speech synthesis. Our experiments are aimed at statistical analysis of cepstral coefficient values and ranges of spectral flatness in three emotions (joy, sadness, anger), and a neutral state for comparison. Calculated histograms of spectral flatness distribution are visually compared and modelled by Gamma probability distribution. Histograms of cepstral coefficient distribution are evaluated and compared using skewness and kurtosis. Achieved statistical results show good correlation comparing male and female voices for all emotional states portrayed by several Czech and Slovak professional actors.

Vibrational Spectra and Density functional calculation of Organic Nonlinear Optic Crystal p-Amino Acetanilide

Energy Technology Data Exchange (ETDEWEB)

Saja, D; Joe, I Hubert; Jayakumar, V S [Department of Physics, Mar Ivanios College, Thiruvananthapuram-695015, Kerala (India)

2006-01-01

The NIR-FT Raman, FT-IR spectral analysis of potential NLO material P-Amino Acetanilide is carried out by density functional computations. The optimized geometry shows that NH2 and NHCOCH3 groups substituted in para position of phenyl ring are non-planar which predicts maximum conjugation of molecule with donor and acceptor groups. Vibrational analysis reveals that simultaneous IR and Raman activation of the phenyl ring modes also provide evidence for the charge transfer interaction between the donors and the acceptor can make the molecule highly polarized and the intra molecular charge transfer interaction must be responsible for the NLO properties of PAA.

Vibrational Spectra and Density functional calculation of Organic Nonlinear Optic Crystal p-Amino Acetanilide

International Nuclear Information System (INIS)

Saja, D; Joe, I Hubert; Jayakumar, V S

2006-01-01

The NIR-FT Raman, FT-IR spectral analysis of potential NLO material P-Amino Acetanilide is carried out by density functional computations. The optimized geometry shows that NH2 and NHCOCH3 groups substituted in para position of phenyl ring are non-planar which predicts maximum conjugation of molecule with donor and acceptor groups. Vibrational analysis reveals that simultaneous IR and Raman activation of the phenyl ring modes also provide evidence for the charge transfer interaction between the donors and the acceptor can make the molecule highly polarized and the intra molecular charge transfer interaction must be responsible for the NLO properties of PAA

First international conference on vibration control in optics and metrology

International Nuclear Information System (INIS)

Baker, L.R.

1987-01-01

This book contains 27 selections. Some of the titles are: Use of optics for vibration analysis of automotive components; Use of pulsed lasers for vibration analysis in the nuclear power industry; Vibration analysis of photocopiers; Control of ground vibrations; Design of low-vibration buildings: two case histories; and Continuous pulsed electronic speckle pattern interferometry

Finite Element Formulation for Stability and Free Vibration Analysis of Timoshenko Beam

Directory of Open Access Journals (Sweden)

Abbas Moallemi-Oreh

2013-01-01

Full Text Available A two-node element is suggested for analyzing the stability and free vibration of Timoshenko beam. Cubic displacement polynomial and quadratic rotational fields are selected for this element. Moreover, it is assumed that shear strain of the element has the constant value. Interpolation functions for displacement field and beam rotation are exactly calculated by employing total beam energy and its stationing to shear strain. By exploiting these interpolation functions, beam elements' stiffness matrix is also examined. Furthermore, geometric stiffness matrix and mass matrix of the proposed element are calculated by writing governing equation on stability and beam free vibration. At last, accuracy and efficiency of proposed element are evaluated through numerical tests. These tests show high accuracy of the element in analyzing beam stability and finding its critical load and free vibration analysis.

The Shock and Vibration Bulletin. Part 2. Measurement Techniques and Data Analysis, Dynamic Measurements, Vibration and Acoustics

Science.gov (United States)

1980-09-01

Smallwood and D. L. Gregory, Sandia Laboratories, Albuquerque, NM A NEW METHOD OF IMPROVING SPECTRA SHAPING IN REVERBERANT CHAMBERS...DAMPING M. M. Wallace and C. W. Bert, The University of Oklahoma, Norman , OK CONTRIBUTIONS TO THE DYNAMIC ANALYSIS OF MAGLEV VEHICLES ON ELEVATED GUIDEWAYS...RANDOM VIBRATION EXTRENAL CONTROL STRATEGY D. 0. Smallwood D. L. Gregory Sandia Laboratories Albuquerque, NM This paper discusses the theoretical basis for

Spectral analysis of Floating Car Data

OpenAIRE

Gössel, F.; Michler, E.; Wrase, B.

2003-01-01

Floating Car Data (FCD) are one important data source in traffic telematic systems. The original variable in these systems is the vehicle velocity. The paper analyses the measured value “vehicle velocity" by methods of information technology. Consequences for processing, transmission and storage of FCD under condition of limited resources are discussed. Starting point of the investigation is the analysis of spectral characteristics of velocity-time-profiles. The spectra are determined by...

Thermal and vibration dynamic analysis of an induction motor using optical fiber Bragg gratings

Science.gov (United States)

Sousa, Kleiton d. M.; Dreyer, Uilian J.; Martelli, Cicero; Cardozo da Silva, Jean Carlos

2015-09-01

In this paper it is presented the results of temperature and vibration measurements in a Three-phase Induction Motor (TIM) running at no-load condition. Vibration and temperature analysis are the most successful techniques used for condition monitoring of induction motors. The vibration is measured using two FBGs installed inside of the motor between two subsequent stator teeth. The motor spectrum of vibration when power is at 60 Hz presents the frequencies 60 Hz, 120 Hz, 180 Hz, and 240 Hz as theoretically expected. For the temperature measurement two FBGs are encapsulated in an alumina tube fixed along the stator. The results show 0.9°C difference between the two FBG caused by the motor ventilation nearer of one FBG. These measurements can be used to determine TIM parameters and still be predictive maintenance tool.

Detection of generator bearing inner race creep by means of vibration and temperature analysis

DEFF Research Database (Denmark)

Skrimpas, Georgios Alexandros; Dragiev, Ivaylo G.; Hilmisson, Reynir

2015-01-01

Vibration and temperature analysis are the two dominating condition monitoring techniques applied to fault detection of bearing failures in wind turbine generators. Relative movement between the bearing inner ring and generator axle is one of the most severe failure modes in terms of secondary...... damages and development. Detection of bearing creep can be achieved reliably based on continuous trending of the amplitude of vibration running speed harmonic and temperature absolute values. In order to decrease the number of condition indicators which need to be assessed, it is proposed to exploit...... a weighted average descriptor calculated based on the 3rd up to 6th harmonic orders. Two cases of different bearing creep severity are presented, showing the consistency of the combined vibration and temperature data utilization. In general, vibration monitoring reveals early signs of abnormality several...

Whole-Body Vibration in Farming: Background Document for Creating a Simplified Procedure to Determine Agricultural Tractor Vibration Comfort

Directory of Open Access Journals (Sweden)

Maurizio Cutini

2017-09-01

Full Text Available Operator exposure to high levels of whole-body vibration (WBV presents risks to health and safety and it is reported to worsen or even cause back injuries. Work activities resulting in operator exposure to whole-body vibration have a common onset in off-road work such as farming. Despite the wide variability of agricultural surface profiles, studies have shown that with changing soil profile and tractor speed, the accelerations resulting from ground input present similar spectral trends. While on the one hand such studies confirmed that tractor WBV emission levels are very dependent upon the nature of the operation performed, on the other, irrespective of the wide range of conditions characterizing agricultural operations, they led researchers to set up a possible and realistic simplification and standardization of tractor driver comfort testing activities. The studies presented herewith indicate the usefulness, and the possibility, of developing simplified procedures to determine agricultural tractor vibration comfort. The results obtained could be used effectively to compare tractors of the same category or a given tractor when equipped with different seats, suspension, tyres, etc.

Evaluation of abrasive waterjet produced titan surfaces topography by spectral analysis techniques

Directory of Open Access Journals (Sweden)

D. Kozak

2012-01-01

Full Text Available Experimental study of a titan grade 2 surface topography prepared by abrasive waterjet cutting is performed using methods of the spectral analysis. Topographic data are acquired by means of the optical profilometr MicroProf®FRT. Estimation of the areal power spectral density of the studied surface is carried out using the periodogram method combined with the Welch´s method. Attention is paid to a structure of the areal power spectral density, which is characterized by means of the angular power spectral density. This structure of the areal spectral density is linked to the fine texture of the surface studied.

Finite Element Analysis for Active-force Control on Vibration of a Flexible Single-link Manipulator

Directory of Open Access Journals (Sweden)

Abdul Kadir Muhammad

2015-10-01

Full Text Available The purposes of this research are to formulate the equations of motion of the system, to develop computational codes by a finite element analysis in order to perform dynamics simulation with vibration control, to propose an effective control scheme using active-force (AF control a flexible single-link manipulator. The system used in this paper consists of an aluminum beam as a flexible link, a clamp-part, a servo motor to rotate the link and a piezoelectric actuator to control vibration. Computational codes on time history responses, FFT (Fast Fourier Transform processing and eigenvalues-eigenvectors analysis were developed to calculate dynamic behavior of the link. Furthermore, the AF control was designed to drive the piezoelectric actuator. Calculated results have revealed that the vibration of the system can be suppressed effectively.

Per-operative vibration analysis: a valuable tool for defining correct stem insertion: preliminary report.

Science.gov (United States)

Mulier, Michiel; Pastrav, Cesar; Van der Perre, Georges

2008-01-01

Defining the stem insertion end point during total hip replacement still relies on the surgeon's feeling. When a custom-made stem prosthesis with an optimal fit into the femoral canal is used, the risk of per-operative fractures is even greater than with standard prostheses. Vibration analysis is used in other clinical settings and has been tested as a means to detect optimal stem insertion in the laboratory. The first per-operative use of vibration analysis during non-cemented custom-made stem insertion in 30 patients is reported here. Thirty patients eligible for total hip replacement with uncemented stem prosthesis were included. The neck of the stem was connected with a shaker that emitted white noise as excitation signal and an impedance head that measured the frequency response. The response signal was sent to a computer that analyzed the frequency response function after each insertion phase. A technician present in the operating theatre but outside the laminated airflow provided feed-back to the surgeon. The correlation index between the frequency response function measured during the last two insertion hammering sessions was >0.99 in 86.7% of the cases. In four cases the surgeon stopped the insertion procedure because of a perceived risk of fracture. Two special cases illustrating the potential benefit of per-operative vibration analysis are described. The results of intra-operative vibration analysis indicate that this technique may be a useful tool assisting the orthopaedic surgeon in defining the insertion endpoint of the stem. The development of a more user-friendly device is therefore warranted.

Analysis of micro vibration in gas film of aerostatic guide way based on molecule collision theory

Directory of Open Access Journals (Sweden)

Yang Shao Hua

2016-01-01

Full Text Available Micro vibration of the aerostatic guide way has a significant impact on its dynamic characteristics and stability, which limits the development of pneumatic component. High pressure gas molecules have been collided with the supporting surface and the internal surface of the throttle during the flow process. Variable impulse of the surfaces aside for the gas film are affected by the changes of impulse which formed irregular impact force in horizontal and vertical direction. Micro-vibration takes place based on the natural frequency of the system and its frequency doubling. In this paper, the vibration model was established to describe the dynamic characteristics of the gas film, and the formation mechanism of micro vibration in the film is defined. Through the simulation analysis and experimental comparison, formation mechanism of the micro vibration in the gas film is confirmed. It was proposed that the micro vibration of gas film can be produced no matter whether there is a gas chamber or not in the throttle. Under the same conditions, the micro vibration of the guide way with air chamber is greater than that without any chamber. The frequency points of the vibration peaks are almost the same, as well as the vibration pattern in the frequency domain.

Automics: an integrated platform for NMR-based metabonomics spectral processing and data analysis

Directory of Open Access Journals (Sweden)

Qu Lijia

2009-03-01

Full Text Available Abstract Background Spectral processing and post-experimental data analysis are the major tasks in NMR-based metabonomics studies. While there are commercial and free licensed software tools available to assist these tasks, researchers usually have to use multiple software packages for their studies because software packages generally focus on specific tasks. It would be beneficial to have a highly integrated platform, in which these tasks can be completed within one package. Moreover, with open source architecture, newly proposed algorithms or methods for spectral processing and data analysis can be implemented much more easily and accessed freely by the public. Results In this paper, we report an open source software tool, Automics, which is specifically designed for NMR-based metabonomics studies. Automics is a highly integrated platform that provides functions covering almost all the stages of NMR-based metabonomics studies. Automics provides high throughput automatic modules with most recently proposed algorithms and powerful manual modules for 1D NMR spectral processing. In addition to spectral processing functions, powerful features for data organization, data pre-processing, and data analysis have been implemented. Nine statistical methods can be applied to analyses including: feature selection (Fisher's criterion, data reduction (PCA, LDA, ULDA, unsupervised clustering (K-Mean and supervised regression and classification (PLS/PLS-DA, KNN, SIMCA, SVM. Moreover, Automics has a user-friendly graphical interface for visualizing NMR spectra and data analysis results. The functional ability of Automics is demonstrated with an analysis of a type 2 diabetes metabolic profile. Conclusion Automics facilitates high throughput 1D NMR spectral processing and high dimensional data analysis for NMR-based metabonomics applications. Using Automics, users can complete spectral processing and data analysis within one software package in most cases

Automics: an integrated platform for NMR-based metabonomics spectral processing and data analysis.

Science.gov (United States)

Wang, Tao; Shao, Kang; Chu, Qinying; Ren, Yanfei; Mu, Yiming; Qu, Lijia; He, Jie; Jin, Changwen; Xia, Bin

2009-03-16

Spectral processing and post-experimental data analysis are the major tasks in NMR-based metabonomics studies. While there are commercial and free licensed software tools available to assist these tasks, researchers usually have to use multiple software packages for their studies because software packages generally focus on specific tasks. It would be beneficial to have a highly integrated platform, in which these tasks can be completed within one package. Moreover, with open source architecture, newly proposed algorithms or methods for spectral processing and data analysis can be implemented much more easily and accessed freely by the public. In this paper, we report an open source software tool, Automics, which is specifically designed for NMR-based metabonomics studies. Automics is a highly integrated platform that provides functions covering almost all the stages of NMR-based metabonomics studies. Automics provides high throughput automatic modules with most recently proposed algorithms and powerful manual modules for 1D NMR spectral processing. In addition to spectral processing functions, powerful features for data organization, data pre-processing, and data analysis have been implemented. Nine statistical methods can be applied to analyses including: feature selection (Fisher's criterion), data reduction (PCA, LDA, ULDA), unsupervised clustering (K-Mean) and supervised regression and classification (PLS/PLS-DA, KNN, SIMCA, SVM). Moreover, Automics has a user-friendly graphical interface for visualizing NMR spectra and data analysis results. The functional ability of Automics is demonstrated with an analysis of a type 2 diabetes metabolic profile. Automics facilitates high throughput 1D NMR spectral processing and high dimensional data analysis for NMR-based metabonomics applications. Using Automics, users can complete spectral processing and data analysis within one software package in most cases. Moreover, with its open source architecture, interested

Impact vibration analysis of group of hexagonal bars immersed in liquid

International Nuclear Information System (INIS)

Horiuchi, Toshihiko

1994-01-01

A simulation method was studied to calculate the vibration response during seismic excitation of a group of hexagonal bars installed in a restraint immersed in liquid. In this study, the influence of fluid force on structural motion was modeled using an added mass matrix. The added mass matrix was then transferred into the space composed of the eigen modes of hexagonal bars without the added mass and introduced into eigenvalue analysis of the whole bar group structure. By means of this method, the computational time of the added mass matrix calculation and the eigenvalue analysis can be reduced. It was shown that the proposed method yielded almost the same eigenvalues as the conventional method in the physical space. Using the proposed method, added mass models to be used in the impact vibration analysis were investigated. Comparing the calculated results by the proposed method with those using a concentrated added mass, which is a simplified model, showed that the concentrated added mass can be used for a rough response calculation, although the precise calculation requires the added mass matrix. (author)

Identification of mechanical vibrations in a PWR reactor using neutron noise signal analysis of the standard instrumentation; Identifikacija mehanichkih varijacija analizom signala shuma standardne neutronske instrumentacije PWR reaktora

Energy Technology Data Exchange (ETDEWEB)

Kostic, Lj [Institut za Nuklearne Nauke Boris Kidric, Belgrade (Yugoslavia); Runkel, J [Institut fuer Kerntechnik und Zerstoerungsfreie Pruefverfahren, Hannover (Germany)

1988-07-01

The neutron noise signals in a PWR power plant were analysed in terms of auto- and cross-power spectral densities, phases and coherences. Core barrel motion, fuel element vibrations and reactivity noise effect due to pressure variations have been monitored and analysed. (author)

Vibration and Noise in Magnetic Resonance Imaging of the Vocal Tract: Differences between Whole-Body and Open-Air Devices

Directory of Open Access Journals (Sweden)

Jiří Přibil

2018-04-01

Full Text Available This article compares open-air and whole-body magnetic resonance imaging (MRI equipment working with a weak magnetic field as regards the methods of its generation, spectral properties of mechanical vibration and acoustic noise produced by gradient coils during the scanning process, and the measured noise intensity. These devices are used for non-invasive MRI reconstruction of the human vocal tract during phonation with simultaneous speech recording. In this case, the vibration and noise have negative influence on quality of speech signal. Two basic measurement experiments were performed within the paper: mapping sound pressure levels in the MRI device vicinity and picking up vibration and noise signals in the MRI scanning area. Spectral characteristics of these signals are then analyzed statistically and compared visually and numerically.

The spectral analysis of motion: An "open field" activity test example

Directory of Open Access Journals (Sweden)

Obradović Z.

2013-01-01

Full Text Available In this work we have described the new mathematical approach, with spectral analysis of the data to evaluate position and motion in the „„open field““ experiments. The aim of this work is to introduce several new parameters mathematically derived from experimental data by means of spectral analysis, and to quantitatively estimate the quality of the motion. Two original software packages (TRACKER and POSTPROC were used for transforming a video data to a log file, suitable for further computational analysis, and to perform analysis from the log file. As an example, results obtained from the experiments with Wistar rats in the „open field“ test are included. The test group of animals was treated with diazepam. Our results demonstrate that all the calculated parameters, such as movement variability, acceleration and deceleration, were significantly lower in the test group compared to the control group. We believe that the application of parameters obtained by spectral analysis could be of great significance in assessing the locomotion impairment in any kind of motion. [Projekat Ministarstva nauke Republike Srbije, br. III41007 i br. ON174028

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.

The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program : Bell Helicopter Textron accomplishments

Science.gov (United States)

Cronkhite, James D.

1993-01-01

Accurate vibration prediction for helicopter airframes is needed to 'fly from the drawing board' without costly development testing to solve vibration problems. The principal analytical tool for vibration prediction within the U.S. helicopter industry is the NASTRAN finite element analysis. Under the NASA DAMVIBS research program, Bell conducted NASTRAN modeling, ground vibration testing, and correlations of both metallic (AH-1G) and composite (ACAP) airframes. The objectives of the program were to assess NASTRAN airframe vibration correlations, to investigate contributors to poor agreement, and to improve modeling techniques. In the past, there has been low confidence in higher frequency vibration prediction for helicopters that have multibladed rotors (three or more blades) with predominant excitation frequencies typically above 15 Hz. Bell's findings under the DAMVIBS program, discussed in this paper, included the following: (1) accuracy of finite element models (FEM) for composite and metallic airframes generally were found to be comparable; (2) more detail is needed in the FEM to improve higher frequency prediction; (3) secondary structure not normally included in the FEM can provide significant stiffening; (4) damping can significantly affect phase response at higher frequencies; and (5) future work is needed in the areas of determination of rotor-induced vibratory loads and optimization.

Vibration analysis method for detection of abnormal movement of material in a rotary dissolver

International Nuclear Information System (INIS)

Smith, C.M.; Fry, D.N.

1978-11-01

Vibration signals generated by the movement of simulated nuclear fuel material through a three-stage, continuous, rotary dissolver were frequency analyzed to determine whether these signals contained characteristic signal patterns that would identify each of five phases of operation in the dissolver and, thus, would indicate the proper movement of material through the dissolver. This characterization of the signals is the first step in the development of a system for monitoring the flow of material through a dissolver to be developed for reprocessing spent nuclear fuel. Vibration signals from accelerometers mounted on the dissolver roller supports were analyzed in a bandwidth from 0 to 10 kHz. The analysis established that (1) all five phases of dissolver operation can be characterized by vibration signatures; (2) four of the five phases of operation can be readily and directly identified by a characteristic vibration signature during continuous, prototypic operation; (3) the transfer of material from the inlet to the dissolution stage can be indirectly monitored by one of the other four vibration signatures (the mixing signature) during prototypic operation; (4) a simulated blockage between the dissolution and exit stages can be detected by changes in one or more characteristic vibration signatures; and (5) a simulated blockage of the exit chute cannot be detected

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

Determination of vibrational parameters of methanol from matrix-isolation infrared spectroscopy and ab initio calculations. Part 1 - Spectral analysis in the domain 11 000-200 cm{sup -1}

Energy Technology Data Exchange (ETDEWEB)

Perchard, J.P. [Universite Pierre et Marie Curie, CNRS, Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075, Case 49, 4 Place Jussieu, 75252 Paris (France)], E-mail: jpp@spmol.jussieu.fr; Romain, F. [Universite Pierre et Marie Curie, CNRS, Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075, Case 49, 4 Place Jussieu, 75252 Paris (France); Bouteiller, Y. [Universite Paris-Nord, CNRS, Laboratoire de Physique des Lasers, UMR 7538, 93430 Villetaneuse (France)

2008-01-22

Infrared spectra of three isotopic species of methanol ({sup 12}CH{sub 3}{sup 16}OH, {sup 13}CH{sub 3}{sup 16}OH, {sup 12}CH{sub 3}{sup 18}OH) trapped in neon and nitrogen matrices have been recorded between 11 000 and 200 cm{sup -1}. Their analysis is based on the isotopic effects which slightly modify the frequencies without significantly changing the nature of vibrations nor the band intensities. From the assignment of most of the two quanta transitions 45 out of the 78 anharmonicity coefficients have been deduced. The value of some of them has been confirmed by the identification of three quanta transitions mainly involving the OH stretching mode. The problem of vibrational resonances between methyl bending and stretching modes has been tackled by performing complementary experiments: use of other isotopic species (CH{sub 3}OD, CH{sub 2}DOH) and acquisition of Raman spectra in the gas phase.

Multi-parameters sensitivity analysis of natural vibration modal for steel arch bridge

Directory of Open Access Journals (Sweden)

WANG Ying

2014-02-01

Full Text Available Because of the vehicle loads and environmental factors,the behaviors of bridge structure in service is becoming deterioration.The modal parameters are important indexes of structure,so sensitivity analysis of natural vibration is an important way to evaluate the behavior of bridge structure.In this paper,using the finite element software Ansys,calculation model of a steel arch bridge was built,and the natural vibration modals were obtained.In order to compare the different sensitivity of material parameters which may affect the natural vibration modal,5 factors were chosen to perform the calculation.The results indicated that different 5 factors had different sensitivity.The leading factor was elastic modulus of arch rib,and the elastic modulus of suspender had little effect to the sensitivity.Another argument was the opposite sensitivity effect happened between the elastic modulus and density of the material.

Automated Bearing Fault Diagnosis Using 2D Analysis of Vibration Acceleration Signals under Variable Speed Conditions

Directory of Open Access Journals (Sweden)

Sheraz Ali Khan

2016-01-01

Full Text Available Traditional fault diagnosis methods of bearings detect characteristic defect frequencies in the envelope power spectrum of the vibration signal. These defect frequencies depend upon the inherently nonstationary shaft speed. Time-frequency and subband signal analysis of vibration signals has been used to deal with random variations in speed, whereas design variations require retraining a new instance of the classifier for each operating speed. This paper presents an automated approach for fault diagnosis in bearings based upon the 2D analysis of vibration acceleration signals under variable speed conditions. Images created from the vibration signals exhibit unique textures for each fault, which show minimal variation with shaft speed. Microtexture analysis of these images is used to generate distinctive fault signatures for each fault type, which can be used to detect those faults at different speeds. A k-nearest neighbor classifier trained using fault signatures generated for one operating speed is used to detect faults at all the other operating speeds. The proposed approach is tested on the bearing fault dataset of Case Western Reserve University, and the results are compared with those of a spectrum imaging-based approach.

Analysis of vibroprotection characteristics of pneumatic relaxation seat suspension with capability of vibration energy recuperation

Directory of Open Access Journals (Sweden)

Lyashenko Mikhail

2017-01-01

Full Text Available This paper proposes mechanism and control algorithm for pneumatic relaxation system of suspension with vibration energy recuperation applied to standard vehicle operator seat (“Sibeko” company. Mathematical model of the seat pneumatic relaxation suspension with two additional air volumes was created. Pneumatic motor – recuperator activated by means of air flow from the one additional volume to another is installed in air piping between additional volumes. Computational research was made in Matlab/Simulink. Amplitude-frequency characteristics of transmission coefficient for standard and proposed suspensions were plotted for preliminary evaluation of vibration protection properties of seat suspension. Performed comparative analysis of amplitude-frequency characteristics shows that noticeable improvement of vibration protection properties of pneumatic relaxation suspension system with vibration energy recuperation in comparison with standard system both in region of resonance disturbances and in above-resonance region. Main ways for further improvement of vibration protection properties of proposed system were marked out.

Parametric image reconstruction using spectral analysis of PET projection data

International Nuclear Information System (INIS)

Meikle, Steven R.; Matthews, Julian C.; Cunningham, Vincent J.; Bailey, Dale L.; Livieratos, Lefteris; Jones, Terry; Price, Pat

1998-01-01

Spectral analysis is a general modelling approach that enables calculation of parametric images from reconstructed tracer kinetic data independent of an assumed compartmental structure. We investigated the validity of applying spectral analysis directly to projection data motivated by the advantages that: (i) the number of reconstructions is reduced by an order of magnitude and (ii) iterative reconstruction becomes practical which may improve signal-to-noise ratio (SNR). A dynamic software phantom with typical 2-[ 11 C]thymidine kinetics was used to compare projection-based and image-based methods and to assess bias-variance trade-offs using iterative expectation maximization (EM) reconstruction. We found that the two approaches are not exactly equivalent due to properties of the non-negative least-squares algorithm. However, the differences are small ( 1 and, to a lesser extent, VD). The optimal number of EM iterations was 15-30 with up to a two-fold improvement in SNR over filtered back projection. We conclude that projection-based spectral analysis with EM reconstruction yields accurate parametric images with high SNR and has potential application to a wide range of positron emission tomography ligands. (author)

Vibration Analysis of a Tire in Ground Contact under Varied Conditions

Directory of Open Access Journals (Sweden)

Karakus Murat

2017-03-01

Full Text Available The effect of three different factors, which are inflation pressure, vertical load and coefficient of friction on the natural frequencies of a tire (175/70 R13 has been studied. A three dimensional tire model is constructed, using four different material properties and parts in the tire. Mechanical properties of the composite parts are evaluated. After investigating the free vibration, contact analysis is carried out. A concrete block and the tire are modelled together, using three different coefficients of friction. Experiments are run under certain conditions to check the accuracy of the numerical model. The natural frequencies are measured to describe free vibration and vibration of the tire contacted by ground, using a damping monitoring method. It is seen, that experimental and numerical results are in good agreement. On the other hand, investigating the impact of three different factors together is quite difficult on the natural frequencies. When some of these factors are assumed to be constant and the variables are taken one by one, it is easier to assess the effects.

Joint Spectral Analysis for Early Bright X-ray Flares of γ-Ray Bursts ...

Indian Academy of Sciences (India)

Abstract. A joint spectral analysis for early bright X-ray flares that were simultaneously observed with Swift BAT and XRT are present. Both BAT and XRT lightcurves of these flares are correlated. Our joint spectral anal- ysis shows that the radiations in the two energy bands are from the same spectral component, which can ...

Employing optical code division multiple access technology in the all fiber loop vibration sensor system

Science.gov (United States)

Tseng, Shin-Pin; Yen, Chih-Ta; Syu, Rong-Shun; Cheng, Hsu-Chih

2013-12-01

This study proposes a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) framework to access the vibration frequency of a test object on the all fiber loop vibration sensor (AFLVS). Each user possesses an individual SAC, and fiber Bragg grating (FBG) encoders/decoders using multiple FBG arrays were adopted, providing excellent orthogonal properties in the frequency domain. The system also mitigates multiple access interference (MAI) among users. When an optical fiber is bent to a point exceeding the critical radius, the fiber loop sensor becomes sensitive to external physical parameters (e.g., temperature, strain, and vibration). The AFLVS involves placing a fiber loop with a specific radius on a designed vibration platform.

Spectral theory and nonlinear analysis with applications to spatial ecology

CERN Document Server

Cano-Casanova, S; Mora-Corral , C

2005-01-01

This volume details some of the latest advances in spectral theory and nonlinear analysis through various cutting-edge theories on algebraic multiplicities, global bifurcation theory, non-linear Schrödinger equations, non-linear boundary value problems, large solutions, metasolutions, dynamical systems, and applications to spatial ecology. The main scope of the book is bringing together a series of topics that have evolved separately during the last decades around the common denominator of spectral theory and nonlinear analysis - from the most abstract developments up to the most concrete applications to population dynamics and socio-biology - in an effort to fill the existing gaps between these fields.

Vibration Analysis and Experimental Research of the Linear-Motor-Driven Water Piston Pump Used in the Naval Ship

Directory of Open Access Journals (Sweden)

Ye-qing Huang

2016-01-01

Full Text Available Aiming at the existing problems of traditional water piston pump used in the naval ship, such as low efficiency, high noise, large vibration, and nonintelligent control, a new type of linear-motor-driven water piston pump is developed and its vibration characteristics are analyzed in this research. Based on the 3D model of the structure, the simulation analyses including static stress analysis, modal analysis, and harmonic response analysis are conducted. The simulation results reveal that the mode shape under low frequency stage is mainly associated with the eccentricity swing of the piston rod. The vibration experiment results show that the resonance frequency of linear-motor-driven water piston pump is concentrated upon 500 Hz and 800 Hz in the low frequency range. The dampers can change the resonance frequency of the system to a certain extent. The vibration under triangular motion curve is much better than that of S curve, which is consistent with the simulation conclusion. This research provides an effective method to detect the vibration characteristics and a reference for design and optimization of the linear-motor-driven water piston pump.

The NASA/industry Design Analysis Methods for Vibrations (DAMVIBS) program: McDonnell-Douglas Helicopter Company achievements

Science.gov (United States)

Toossi, Mostafa; Weisenburger, Richard; Hashemi-Kia, Mostafa

1993-01-01

This paper presents a summary of some of the work performed by McDonnell Douglas Helicopter Company under NASA Langley-sponsored rotorcraft structural dynamics program known as DAMVIBS (Design Analysis Methods for VIBrationS). A set of guidelines which is applicable to dynamic modeling, analysis, testing, and correlation of both helicopter airframes and a large variety of structural finite element models is presented. Utilization of these guidelines and the key features of their applications to vibration modeling of helicopter airframes are discussed. Correlation studies with the test data, together with the development and applications of a set of efficient finite element model checkout procedures, are demonstrated on a large helicopter airframe finite element model. Finally, the lessons learned and the benefits resulting from this program are summarized.

Euler deconvolution and spectral analysis of regional aeromagnetic ...

African Journals Online (AJOL)

Existing regional aeromagnetic data from the south-central Zimbabwe craton has been analysed using 3D Euler deconvolution and spectral analysis to obtain quantitative information on the geological units and structures for depth constraints on the geotectonic interpretation of the region. The Euler solution maps confirm ...

Development of spectral analysis math models and software program and spectral analyzer, digital converter interface equipment design

Science.gov (United States)

Hayden, W. L.; Robinson, L. H.

1972-01-01

Spectral analyses of angle-modulated communication systems is studied by: (1) performing a literature survey of candidate power spectrum computational techniques, determining the computational requirements, and formulating a mathematical model satisfying these requirements; (2) implementing the model on UNIVAC 1230 digital computer as the Spectral Analysis Program (SAP); and (3) developing the hardware specifications for a data acquisition system which will acquire an input modulating signal for SAP. The SAP computational technique uses extended fast Fourier transform and represents a generalized approach for simple and complex modulating signals.

Wavelet analysis for nonstationary signals

International Nuclear Information System (INIS)

Penha, Rosani Maria Libardi da

1999-01-01

Mechanical vibration signals play an important role in anomalies identification resulting of equipment malfunctioning. Traditionally, Fourier spectral analysis is used where the signals are assumed to be stationary. However, occasional transient impulses and start-up process are examples of nonstationary signals that can be found in mechanical vibrations. These signals can provide important information about the equipment condition, as early fault detection. The Fourier analysis can not adequately be applied to nonstationary signals because the results provide data about the frequency composition averaged over the duration of the signal. In this work, two methods for nonstationary signal analysis are used: Short Time Fourier Transform (STFT) and wavelet transform. The STFT is a method of adapting Fourier spectral analysis for nonstationary application to time-frequency domain. To have a unique resolution throughout the entire time-frequency domain is its main limitation. The wavelet transform is a new analysis technique suitable to nonstationary signals, which handles the STFT drawbacks, providing multi-resolution frequency analysis and time localization in a unique time-scale graphic. The multiple frequency resolutions are obtained by scaling (dilatation/compression) the wavelet function. A comparison of the conventional Fourier transform, STFT and wavelet transform is made applying these techniques to: simulated signals, arrangement rotor rig vibration signal and rotate machine vibration signal Hanning window was used to STFT analysis. Daubechies and harmonic wavelets were used to continuos, discrete and multi-resolution wavelet analysis. The results show the Fourier analysis was not able to detect changes in the signal frequencies or discontinuities. The STFT analysis detected the changes in the signal frequencies, but with time-frequency resolution problems. The wavelet continuos and discrete transform demonstrated to be a high efficient tool to detect

Investigating cardiorespiratory interaction by cross-spectral analysis of event series

Science.gov (United States)

Schäfer, Carsten; Rosenblum, Michael G.; Pikovsky, Arkady S.; Kurths, Jürgen

2000-02-01

The human cardiovascular and respiratory systems interact with each other and show effects of modulation and synchronization. Here we present a cross-spectral technique that specifically considers the event-like character of the heartbeat and avoids typical restrictions of other spectral methods. Using models as well as experimental data, we demonstrate how modulation and synchronization can be distinguished. Finally, we compare the method to traditional techniques and to the analysis of instantaneous phases.

Analysis of the vibration of the vehicle body with the elimination of the influence of tires

Directory of Open Access Journals (Sweden)

Łukasz KONIECZNY

2015-09-01

Full Text Available The article presented the results of vibration measurements of selected elements of the vehicle during the test vibration carried out on a bench with a harmonic kinematic extortion. The results of research carried out for the car when replacing tire and wheels steel tripod eliminating the influence of elasticity and damping tires. The tests were performed at various values of the shock absorber fluid filling (from 100% to 50% of the shock absorber fluid. For registered vibration acceleration STFT analysis was performed.

FT-IR, FT-Raman, NMR studies and ab initio-HF, DFT-B3LYP vibrational analysis of 4-chloro-2-fluoroaniline.

Science.gov (United States)

Arivazhagan, M; Anitha Rexalin, D

2012-10-01

The Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectra of 4-chloro-2-fluoroaniline (CFA) have been recorded and analyzed. The equilibrium geometry, bonding features and harmonic vibrational frequencies have been investigated with the help of ab initio and density functional theory (DFT) methods. The assignments of the vibrational spectra have been carried out with the help of normal coordinate analysis (NCA) following the scaled quantum mechanical force field methodology. The (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule are calculated by the Gauge including atomic orbital (GIAO) method. The first order hyperpolarizability (β(0)) of this novel molecular system and related properties (β, α(0) and Δα) of CFA are calculated using B3LYP/6-311++G(d,p) and HF/6-311++G(d,p) methods on the finite-field approach. The calculated results also show that the CFA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond orbital (NBO) analysis. The result confirms the occurrence of intramolecular charge transfer (ICT) within the molecule. The HOMO-LUMO energies UV-vis spectral analysis and MEP are performed by B3LYP/6-311++G(d,p) approach. A detailed interpretation of the infrared and Raman spectra of CFA is also reported based on total energy distribution (TED). The difference between the observed and scaled wave number values of the most of the fundamentals is very small. Copyright © 2012 Elsevier B.V. All rights reserved.

Dynamic analysis of smart composite beams by using the frequency domain spectral element method

Energy Technology Data Exchange (ETDEWEB)

Park, Il Wook; Lee, Usik [Inha Univ., Incheon (Korea, Republic of)

2012-08-15

To excite or measure the dynamic responses of a laminated composite structure for the active controls of vibrations or noises, wafertype piezoelectric transducers are often bonded on the surface of the composite structure to form a multi layer smart composite structure. Thus, for such smart composite structures, it is very important to develop and use a very reliable mathematical and/or computational model for predicting accurate dynamic characteristics. In this paper, the axial-bending coupled equations of motion and boundary conditions are derived for two layer smart composite beams by using the Hamilton's principle with Lagrange multipliers. The spectral element model is then formulated in the frequency domain by using the variation approach. Through some numerical examples, the extremely high accuracy of the present spectral element model is verified by comparing with the solutions by the conventional finite element model provided in this paper. The effects of the lay up of composite laminates and surface bonded wafer type piezoelectric (PZT) layer on the dynamics and wave characteristics of smart composite beams are investigated. The effective constraint forces at the interface between the base beam and PZT layer are also investigated via Lagrange multipliers.

Experimental Analysis of a Piezoelectric Energy Harvesting System for Harmonic, Random, and Sine on Random Vibration

Energy Technology Data Exchange (ETDEWEB)

Cryns, Jackson W.; Hatchell, Brian K.; Santiago-Rojas, Emiliano; Silvers, Kurt L.

2013-07-01

Formal journal article Experimental analysis of a piezoelectric energy harvesting system for harmonic, random, and sine on random vibration Abstract: Harvesting power with a piezoelectric vibration powered generator using a full-wave rectifier conditioning circuit is experimentally compared for varying sinusoidal, random and sine on random (SOR) input vibration scenarios. Additionally, the implications of source vibration characteristics on harvester design are discussed. Studies in vibration harvesting have yielded numerous alternatives for harvesting electrical energy from vibrations but piezoceramics arose as the most compact, energy dense means of energy transduction. The rise in popularity of harvesting energy from ambient vibrations has made piezoelectric generators commercially available. Much of the available literature focuses on maximizing harvested power through nonlinear processing circuits that require accurate knowledge of generator internal mechanical and electrical characteristics and idealization of the input vibration source, which cannot be assumed in general application. In this manuscript, variations in source vibration and load resistance are explored for a commercially available piezoelectric generator. We characterize the source vibration by its acceleration response for repeatability and transcription to general application. The results agree with numerical and theoretical predictions for in previous literature that load optimal resistance varies with transducer natural frequency and source type, and the findings demonstrate that significant gains are seen with lower tuned transducer natural frequencies for similar source amplitudes. Going beyond idealized steady state sinusoidal and simplified random vibration input, SOR testing allows for more accurate representation of real world ambient vibration. It is shown that characteristic interactions from more complex vibrational sources significantly alter power generation and power processing

Vibrational Spectroscopy as a Promising Toolbox for Analyzing Functionalized Ceramic Membranes.

Science.gov (United States)

Kiefer, Johannes; Bartels, Julia; Kroll, Stephen; Rezwan, Kurosch

2018-01-01

Ceramic materials find use in many fields including the life sciences and environmental engineering. For example, ceramic membranes have shown to be promising filters for water treatment and virus retention. The analysis of such materials, however, remains challenging. In the present study, the potential of three vibrational spectroscopic methods for characterizing functionalized ceramic membranes for water treatment is evaluated. For this purpose, Raman scattering, infrared (IR) absorption, and solvent infrared spectroscopy (SIRS) were employed. The data were analyzed with respect to spectral changes as well as using principal component analysis (PCA). The Raman spectra allow an unambiguous discrimination of the sample types. The IR spectra do not change systematically with functionalization state of the material. Solvent infrared spectroscopy allows a systematic distinction and enables studying the molecular interactions between the membrane surface and the solvent.

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

Nonlinear vibration analysis of a rotor supported by magnetic bearings using homotopy perturbation method

Directory of Open Access Journals (Sweden)

Aboozar Heydari

2017-09-01

Full Text Available In this paper, the effects of nonlinear forces due to the electromagnetic field of bearing and the unbalancing force on nonlinear vibration behavior of a rotor is investigated. The rotor is modeled as a rigid body that is supported by two magnetic bearings with eight-polar structures. The governing dynamics equations of the system that are coupled nonlinear second order ordinary differential equations (ODEs are derived, and for solving these equations, the homotopy perturbation method (HPM is used. By applying HPM, the possibility of presenting a harmonic semi-analytical solution, is provided. In fact, with equality the coefficient of auxiliary parameter (p, the system of coupled nonlinear second order and non-homogenous differential equations are obtained so that consists of unbalancing effects. By considering some initial condition for displacement and velocity in the horizontal and vertical directions, free vibration analysis is done and next, the forced vibration analysis under the effect of harmonic forces also is investigated. Likewise, various parameters on the vibration behavior of rotor are studied. Changes in amplitude and response phase per excitation frequency are investigated. Results show that by increasing excitation frequency, the motion amplitude is also increases and by passing the critical speed, it decreases. Also it shows that the magnetic bearing system performance is in stable maintenance of rotor. The parameters affecting on vibration behavior, has been studied and by comparison the results with the other references, which have a good precision up to 2nd order of embedding parameter, it implies the accuracy of this method in current research.

An Improved Spectral Analysis Method for Fatigue Damage Assessment of Details in Liquid Cargo Tanks

Science.gov (United States)

Zhao, Peng-yuan; Huang, Xiao-ping

2018-03-01

Errors will be caused in calculating the fatigue damages of details in liquid cargo tanks by using the traditional spectral analysis method which is based on linear system, for the nonlinear relationship between the dynamic stress and the ship acceleration. An improved spectral analysis method for the assessment of the fatigue damage in detail of a liquid cargo tank is proposed in this paper. Based on assumptions that the wave process can be simulated by summing the sinusoidal waves in different frequencies and the stress process can be simulated by summing the stress processes induced by these sinusoidal waves, the stress power spectral density (PSD) is calculated by expanding the stress processes induced by the sinusoidal waves into Fourier series and adding the amplitudes of each harmonic component with the same frequency. This analysis method can take the nonlinear relationship into consideration and the fatigue damage is then calculated based on the PSD of stress. Take an independent tank in an LNG carrier for example, the accuracy of the improved spectral analysis method is proved much better than that of the traditional spectral analysis method by comparing the calculated damage results with the results calculated by the time domain method. The proposed spectral analysis method is more accurate in calculating the fatigue damages in detail of ship liquid cargo tanks.

Vibrational spectra of 1-hydroxy- and 1,4-dihydroxyanthraquinones and their magnesium chelate complexes. I. Isotopic effects of OH/OD and 24Mg/26Mg substitutions

International Nuclear Information System (INIS)

Kirszenbaum, Marek

1977-01-01

The vibrational spectra of 1-hydroxy- and 1,4-dihydroxyanthraquinones, their deuterated derivatives and their 24 Mg/ 26 Mg chelate complexes are examined in the spectral region 1700-250cm -1 . The study of deuteroxyanthraquinones allow an assignment of the OH/OD group vibrations and show the multiple coupling of the delta OH vibrations with the vCC and delta CH quinonic vibrations. These results lead to a modification of some spectral assignments of magnesium chelate complexe of 1-OH-AQ. The isotopic 24 Mg/ 26 Mg substitution enables the chelate ring vibrations which depend on the motions of the magnesium atom to be observed. The vC=O and vC-O vibrations frequencies of magnesium chelate complexe [Mg(1,4-O 2 -AQ)]sub(n) show an important difference of the chelate ring electronic state in comparison of those of 1,4-(OH) 2 -AQ. The discussion of the infrared and Raman spectra in the Mg-O vibrations region lead to the conclusion that the configuration of oxygens arround the magnesium is tetrahedral [fr

Finite Element Analysis and Experimental Study on Elbow Vibration Transmission Characteristics

Science.gov (United States)

Qing-shan, Dai; Zhen-hai, Zhang; Shi-jian, Zhu

2017-11-01

Pipeline system vibration is one of the significant factors leading to the vibration and noise of vessel. Elbow is widely used in the pipeline system. However, the researches about vibration of elbow are little, and there is no systematic study. In this research, we firstly analysed the relationship between elbow vibration transmission characteristics and bending radius by ABAQUS finite element simulation. Then, we conducted the further vibration test to observe the vibration transmission characteristics of different elbows which have the same diameter and different bending radius under different flow velocity. The results of simulation calculation and experiment both showed that the vibration acceleration levels of the pipeline system decreased with the increase of bending radius of the elbow, which was beneficial to reduce the transmission of vibration in the pipeline system. The results could be used as reference for further studies and designs for the low noise installation of pipeline system.

Vibration monitoring with artificial neural networks

International Nuclear Information System (INIS)

Alguindigue, I.

1991-01-01

Vibration monitoring of components in nuclear power plants has been used for a number of years. This technique involves the analysis of vibration data coming from vital components of the plant to detect features which reflect the operational state of machinery. The analysis leads to the identification of potential failures and their causes, and makes it possible to perform efficient preventive maintenance. Earlydetection is important because it can decrease the probability of catastrophic failures, reduce forced outgage, maximize utilization of available assets, increase the life of the plant, and reduce maintenance costs. This paper documents our work on the design of a vibration monitoring methodology based on neural network technology. This technology provides an attractive complement to traditional vibration analysis because of the potential of neural network to operate in real-time mode and to handle data which may be distorted or noisy. Our efforts have been concentrated on the analysis and classification of vibration signatures collected from operating machinery. Two neural networks algorithms were used in our project: the Recirculation algorithm for data compression and the Backpropagation algorithm to perform the actual classification of the patterns. Although this project is in the early stages of development it indicates that neural networks may provide a viable methodology for monitoring and diagnostics of vibrating components. Our results to date are very encouraging

The obscure factor analysis on the vibration reliability of the internals of nuclear power plant reactor and anti-vibration measures

International Nuclear Information System (INIS)

Fu Geyan; Zhu Qirong

1998-11-01

It is pointed out that the main reason making nuclear power plants reactors leak is the vibration of internals of reactors. The factors which lead the vibration all have randomness and obscureness. The obscure reliability theory is introduced to the vibration system of internals of nuclear power reactor. Based on a quantity of designing and moving data, the obscure factors effecting the vibration reliability of the internals of nuclear power plant reactor are analyzed and the anti-vibration reliability criteria and the evaluating model are given. And the anti-vibration reliability measures are advanced from different quarters of the machine design and building, the thermohydraulics design, the control of reactivity, etc.. They may benefit the theory and practice for building and perfecting the vibration obscure reliability model of the reactor internals

Verification of hybrid analysis concept of soil-foundation interaction by field vibration tests - Analytical phase

International Nuclear Information System (INIS)

Katayama, I.; Niwa, A.; Kubo, Y.; Penzien, J.

1987-01-01

In connection with the previous paper under the same subject, which describes the results obtained by the field vibration tests of five different models, this paper describes the outline of the hybrid analysis code of soil-structure interaction (HASSI) and the results of numerical simulation of the responses obtained at the model 2C in both cases of the forced vibration test and the natural earthquake excitation

Vibrational spectroscopic study and NBO analysis on tranexamic acid using DFT method

Science.gov (United States)

Muthu, S.; Prabhakaran, A.

2014-08-01

In this work, we reported the vibrational spectra of tranexamic acid (TA) by experimental and quantum chemical calculation. The solid phase FT-Raman and FT-IR spectra of the title compound were recorded in the region 4000 cm-1 to 100 cm-1 and 4000 cm-1 to 400 cm-1 respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of TA in the ground state have been calculated by using density functional theory (DFT) B3LYP method with standard 6-31G(d,p) basis set. The scaled theoretical wavenumber showed very good agreement with the experimental values. The vibrational assignments were performed on the basis of the potential energy distribution (PED) of the vibrational modes. Stability of the molecule, arising from hyperconjugative interactions and charge delocalization, has been analyzed using Natural Bond Orbital (NBO) analysis. The results show that ED in the σ* and π* antibonding orbitals and second order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule. The electrostatic potential mapped onto an isodensity surface has been obtained. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase.

Stochastic modeling of friction force and vibration analysis of a mechanical system using the model

International Nuclear Information System (INIS)

Kang, Won Seok; Choi, Chan Kyu; Yoo, Hong Hee

2015-01-01

The squeal noise generated from a disk brake or chatter occurred in a machine tool primarily results from friction-induced vibration. Since friction-induced vibration is usually accompanied by abrasion and lifespan reduction of mechanical parts, it is necessary to develop a reliable analysis model by which friction-induced vibration phenomena can be accurately analyzed. The original Coulomb's friction model or the modified Coulomb friction model employed in most commercial programs employs deterministic friction coefficients. However, observing friction phenomena between two contact surfaces, one may observe that friction coefficients keep changing due to the unevenness of contact surface, temperature, lubrication and humidity. Therefore, in this study, friction coefficients are modeled as random parameters that keep changing during the motion of a mechanical system undergoing friction force. The integrity of the proposed stochastic friction model was validated by comparing the analysis results obtained by the proposed model with experimental results.

Coupled Boundary and Finite Element Analysis of Vibration from Railway Tunnels

DEFF Research Database (Denmark)

Andersen, Lars; Jones, C. J. C.

2004-01-01

axis, it is useful to evaluate the potential uses of two-dimensional models before committing to much more costly three-dimensional approaches. The vibration forces in the track due to the passage of a train are by nature three-dimensional and a complete analysis undoubtedly requires a model of three...

PCA determination of the radiometric noise of high spectral resolution infrared observations from spectral residuals: Application to IASI

Science.gov (United States)

Serio, C.; Masiello, G.; Camy-Peyret, C.; Jacquette, E.; Vandermarcq, O.; Bermudo, F.; Coppens, D.; Tobin, D.

2018-02-01

The problem of characterizing and estimating the instrumental or radiometric noise of satellite high spectral resolution infrared spectrometers directly from Earth observations is addressed in this paper. An approach has been developed, which relies on the Principal Component Analysis (PCA) with a suitable criterion to select the optimal number of PC scores. Different selection criteria have been set up and analysed, which is based on the estimation theory of Least Squares and/or Maximum Likelihood Principle. The approach is independent of any forward model and/or radiative transfer calculations. The PCA is used to define an orthogonal basis, which, in turn, is used to derive an optimal linear reconstruction of the observations. The residual vector that is the observation vector minus the calculated or reconstructed one is then used to estimate the instrumental noise. It will be shown that the use of the spectral residuals to assess the radiometric instrumental noise leads to efficient estimators, which are largely independent of possible departures of the true noise from that assumed a priori to model the observational covariance matrix. Application to the Infrared Atmospheric Sounder Interferometer (IASI) has been considered. A series of case studies has been set up, which make use of IASI observations. As a major result, the analysis confirms the high stability and radiometric performance of IASI. The approach also proved to be efficient in characterizing noise features due to mechanical micro-vibrations of the beam splitter of the IASI instrument.

Spectral Analysis Methods of Social Networks

Directory of Open Access Journals (Sweden)

P. G. Klyucharev

2017-01-01

Full Text Available Online social networks (such as Facebook, Twitter, VKontakte, etc. being an important channel for disseminating information are often used to arrange an impact on the social consciousness for various purposes - from advertising products or services to the full-scale information war thereby making them to be a very relevant object of research. The paper reviewed the analysis methods of social networks (primarily, online, based on the spectral theory of graphs. Such methods use the spectrum of the social graph, i.e. a set of eigenvalues of its adjacency matrix, and also the eigenvectors of the adjacency matrix.Described measures of centrality (in particular, centrality based on the eigenvector and PageRank, which reflect a degree of impact one or another user of the social network has. A very popular PageRank measure uses, as a measure of centrality, the graph vertices, the final probabilities of the Markov chain, whose matrix of transition probabilities is calculated on the basis of the adjacency matrix of the social graph. The vector of final probabilities is an eigenvector of the matrix of transition probabilities.Presented a method of dividing the graph vertices into two groups. It is based on maximizing the network modularity by computing the eigenvector of the modularity matrix.Considered a method for detecting bots based on the non-randomness measure of a graph to be computed using the spectral coordinates of vertices - sets of eigenvector components of the adjacency matrix of a social graph.In general, there are a number of algorithms to analyse social networks based on the spectral theory of graphs. These algorithms show very good results, but their disadvantage is the relatively high (albeit polynomial computational complexity for large graphs.At the same time it is obvious that the practical application capacity of the spectral graph theory methods is still underestimated, and it may be used as a basis to develop new methods.The work

OPTIMAL AUTOMOBILE MUFFLER VIBRATION AND NOISE ANALYSIS

Directory of Open Access Journals (Sweden)

Sujit Kumar Jha

2013-06-01

Full Text Available The muffler is the main part of the Automobile Exhaust System, consisting of fibrous and porous materials to absorb noise and vibrations. The exhaust gas mass coming from the engine can produce resonance, which may be the source of fatigue failure in the exhaust pipe due to the presence of continuous resonance. The modes on the muffler should be located away from the engine’s operating frequencies in order to minimise the resonance. The objective of this paper is to determine the frequencies that appear at the modes, which have the more adverse effect during the operation of the automobile. An impact test has been conducted by applying the force using a hard head hammer, and data generated have been used for plotting a graph of the transfer functions using MATLAB. Six points have been selected, namely 1, 2, 3, 4, 7, and 11 on the muffler for the impact test. The collected data from theses six points have been analysed for the addition of damping. Results suggests that increasing the mass increases the damping and lowers the modes of the transfer function. Further research will identify higher strength materials that can withstand the higher gas temperatures as well as the corrosion and erosion by the gas emitted from the engine. muffler, noise, vibration,modal analysis,

Leak detection in pipelines through spectral analysis of pressure signals

Directory of Open Access Journals (Sweden)

Souza A.L.

2000-01-01

Full Text Available The development and test of a technique for leak detection in pipelines is presented. The technique is based on the spectral analysis of pressure signals measured in pipeline sections where the formation of stationary waves is favoured, allowing leakage detection during the start/stop of pumps. Experimental tests were performed in a 1250 m long pipeline for various operational conditions of the pipeline (liquid flow rate and leakage configuration. Pressure transients were obtained by four transducers connected to a PC computer. The obtained results show that the spectral analysis of pressure transients, together with the knowledge of reflection points provide a simple and efficient way of identifying leaks during the start/stop of pumps in pipelines.

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.

Estimation and analysis of spectral solar radiation over Cairo

International Nuclear Information System (INIS)

Abdel Wahab, M.M.; Omran, M.

1994-05-01

This work presents a methodology to estimate spectral diffuse and global radiation on horizontal surface. This method is validated by comparing with measured direct and global spectral radiation in four bands. The results show a good performance in cloudless conditions. The analysis of the ratio of surface values to extraterrestrial ones revealed an over-all depletion in the summer months. Also there was no evidence for any tendency for conversion of radiational components through different bands. The model presents excellent agreement with the measured values for (UV/G) ratio. (author). 7 refs, 4 figs, 3 tabs

Small and inconsistent effects of whole body vibration on athletic performance : a systematic review and meta-analysis

NARCIS (Netherlands)

Hortobagyi, Tibor; Lesinski, Melanie; Fernandez-del-Olmo, Miguel; Granacher, Urs

We quantified the acute and chronic effects of whole body vibration on athletic performance or its proxy measures in competitive and/or elite athletes. Systematic literature review and meta-analysis. Whole body vibration combined with exercise had an overall 0.3 % acute effect on maximal voluntary

Common faults in turbines and applying neural networks in order to fault diagnostic by vibration analysis

International Nuclear Information System (INIS)

Masoudifar, M.; AghaAmini, M.

2001-01-01

Today the fault diagnostic of the rotating machinery based on the vibration analysis is an effective method in designing predictive maintenance programs. In this method, vibration level of the turbines is monitored and if it is higher than the allowable limit, vibrational data will be analyzed and the growing faults will be detected. But because of the high complexity of the system monitoring, the interpretation of the measured data is more difficult. Therefore, design of the fault diagnostic expert systems by using the expert's technical experiences and knowledge; seem to be the best solution. In this paper,at first several common faults in turbines are studied and the how applying the neural networks to interpret the vibrational data for fault diagnostic is explained

Numerical analysis using state space method for vibration control of ...

African Journals Online (AJOL)

In passenger cars the vibrations developed at the ground are transmitted to the passengers through seats. Due to vibrations discomfort is experienced by the passengers. Dampers are being successfully utilized to reduce the vibrations in civil engineering structures. Few dampers are used in passenger cars as well.

Vibrational spectroscopy and structural analysis of uranium complexes

Energy Technology Data Exchange (ETDEWEB)

Umrejko, D.S.; Nikanovich, M.V.

1984-12-01

On the basis of experimental and theoretical studies of vibbrational spectra for halides, sulfates, phosphates, uranyl oxalates (and uranium) as well as for more complicated complex systems, reliable spectroscopic criteria have been established for estimation of their structural features by more simple and accessible (than direct) methods. Due to coordination to a central ion of U/sup 6/(U/sup 4/) ligands a geometry variation specific for each method of addition occurs and concomitant redistribution of the force interaction in the mentioned system as well, which directly affects the variation of their frequency characteristics and vibration modes. On this ground stable indications of particular types of coordination for mono- and polyatomic groups (including bridge-type, characteristic of polymetric structures) are pointed out in the IR absorption and Raman spectra. In the investigated structures the predominant effect of coordination on the spectral properties of complexes, as compared with other factors (for example, outer-sphere binding) is established. The presence of water molecules in an interlayer space does not tell essentially on the state of polyatomic ligands with all donor atoms bound with the uranium central atom (particularly, in binary uranyl phosphates). In the presence of free oxygen atoms the H/sub 2/O effect can lead only to some shift of the maxima of separate bands and their additional weak splitting (in uranyl sulfates).

Spectral analysis of bedform dynamics

DEFF Research Database (Denmark)

Winter, Christian; Ernstsen, Verner Brandbyge; Noormets, Riko

Successive multibeam echo sounder surveys in tidal channels off Esbjerg (Denmark) on the North Sea coast reveal the dynamics of subaquatic compound dunes. Mainly driven by tidal currents, dune structures show complex migration patterns in all temporal and spatial scales. Common methods for the an....... The proposed method overcomes the above mentioned problems of common descriptive analysis as it is an objective and straightforward mathematical process. The spectral decomposition of superimposed dunes allows a detailed description and analysis of dune patterns and migration.......Successive multibeam echo sounder surveys in tidal channels off Esbjerg (Denmark) on the North Sea coast reveal the dynamics of subaquatic compound dunes. Mainly driven by tidal currents, dune structures show complex migration patterns in all temporal and spatial scales. Common methods...... allows the application of a procedure, which has been a standard for the analysis of water waves for long times: The bathymetric signal of a cross-section of subaquatic compound dunes is approximated by the sum of a set of harmonic functions, derived by Fourier transformation. If the wavelength...

Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu2(Fe,Zn)SnS4

International Nuclear Information System (INIS)

Fontané, X.; Izquierdo-Roca, V.; Saucedo, E.; Schorr, S.; Yukhymchuk, V.O.; Valakh, M.Ya.; Pérez-Rodríguez, A.; Morante, J.R.

2012-01-01

Highlights: ► Analysis of main and weaker Raman peaks from Cu 2 FeZnS 4 and Cu 2 ZnSnS 4 compounds. ► Identification of a cation disorder induced Raman peak in Cu 2 ZnSnS 4 . ► Analysis of spectral features of main Raman peaks from Cu 2 (Fe,Zn)SnS 4 . - Abstract: This work reports the analysis of the vibrational properties of stannite–kesterite Cu 2 (Fe,Zn)SnS 4 compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu 2 FeSnS 4 (CFTS) and kesterite Cu 2 ZnSnS 4 (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm −1 . This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A 1 peak with the chemical composition.

Experimental and DFT studies of (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline: Electronic and vibrational properties

Science.gov (United States)

Sun, Wenqi; Yuan, Guozan; Liu, Jingxin; Ma, Li; Liu, Chengbu

2013-04-01

The title molecule (E)-2-[2-(2,6-dichlorophenyl)ethenyl]-8-hydroxyquinoline (DPEQ) was synthesized and characterized by FT-IR, UV-vis, NMR spectroscopy. The molecular geometry, vibrational frequencies and gauge independent atomic orbital (GIAO) 1H and 13C NMR chemical shift values of the compound in the ground state have been calculated by using the density functional theory (DFT) method. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program. The calculated results indicate that the theoretical vibrational frequencies, 1H and 13C NMR chemical shift values show good agreement with experimental data. The electronic properties like UV-vis spectral analysis and HOMO-LUMO analysis of DPEQ have been reported and compared with experimental data. Information about the size, shape, charge density distribution and site of chemical reactivity of the molecule has been obtained by mapping electron density isosurface with molecular electrostatic potential (MEP).

Flow-induced vibration and flow characteristics prediction for a sliding roller gate by two-dimensional unsteady CFD simulation

Energy Technology Data Exchange (ETDEWEB)

Kim, Nak-Geun; Lee, Kye-Bock [Chungbuk National University, Cheongju (Korea, Republic of); Cho, Yong [Korea Water Resources Corporation, Daejeon (Korea, Republic of)

2017-07-15

Numerical analysis on the flow induced vibration and flow characteristics in the water gate has been carried out by 2-dimensional unsteady CFD simulation when sea water flows into the port in the river. Effect of gate opening on the frequency and the mean velocity and the vortex shedding under the water gate were studied. The streamlines were compared for various gate openings. To get the frequency spectrum, Fourier transform should be performed. Spectral analysis of the excitation force signals permitted identification of the main characteristics of the interaction process. The results show that the sources of disturbed frequency are the vortex shedding from under the water gate. As the gate opening ratio increases, the predicted vibration frequency decreases. The bottom scouring occurs for large gate opening rather than smaller one. The unstable operation conditions can be estimated by using the CFD results and the Strouhal number results for various gate opening gaps.

Flow-induced vibration and flow characteristics prediction for a sliding roller gate by two-dimensional unsteady CFD simulation

International Nuclear Information System (INIS)

Kim, Nak-Geun; Lee, Kye-Bock; Cho, Yong

2017-01-01

Numerical analysis on the flow induced vibration and flow characteristics in the water gate has been carried out by 2-dimensional unsteady CFD simulation when sea water flows into the port in the river. Effect of gate opening on the frequency and the mean velocity and the vortex shedding under the water gate were studied. The streamlines were compared for various gate openings. To get the frequency spectrum, Fourier transform should be performed. Spectral analysis of the excitation force signals permitted identification of the main characteristics of the interaction process. The results show that the sources of disturbed frequency are the vortex shedding from under the water gate. As the gate opening ratio increases, the predicted vibration frequency decreases. The bottom scouring occurs for large gate opening rather than smaller one. The unstable operation conditions can be estimated by using the CFD results and the Strouhal number results for various gate opening gaps.

Investigation and analysis the vibration of handles of chainsaw without cutting

Directory of Open Access Journals (Sweden)

M Feyzi

2016-04-01

Full Text Available Introduction: Nowadays most of the agricultural and industrial tasks are performed using different machines and almost any people are exposed to the vibration of these machines. Just as sound can be either music to the ear or irritating noise, human vibrations can either be pleasant or unpleasant. Whole-body vibration and hand-arm vibration are two main types of unpleasant vibration. The hand-arm transmitted vibration can cause complex vascular, neurological and musculoskeletal disorder, collectively named as hand-arm vibration syndrome. The chainsaw is a portable machine, powered by a two-stroke engine. This machine is used by tree surgeons to fell trees, remove branches, and other activities such as prune trees. The chainsaw exposes own operators to high level of hand-arm vibration which can lead to problems such as vibration white finger syndrome and Raynaud's phenomenon. White finger syndrome affects the nerves, blood vessels, muscles, and joints of the hand, wrist and arm. It is clear that before trying to control the vibrations, the level of vibrations should be identified. Therefore, an investigation on the vibration level of this machine is crucial. Materials and Methods: The Stihl-MS230 chainsaw was selected in this study. The size of this type of chainsaw is middle and it is equipped with anti-vibration system. According to the ISO-7505 standard, vibration must be measured at three speed level of engine. First at idling speed, second at nominal speed and third at 133% of the nominal speed or maximum speed of engine whichever is less (Racing. So 2800, 10000, and 13300 RPM Engine speed were selected. One of the employed accessories was ARMA ETI-TACHO tachometer which had been fabricated in Taiwan. The vibrations were measured and analyzed using the portable data acquisition system (Easy Viber. During the measurements, data acquisition system was powered by internal batteries. The vibrations were sensed by the piezoelectric accelerometer

Technical Training on High-Order Spectral Analysis and Thermal Anemometry Applications

Science.gov (United States)

Maslov, A. A.; Shiplyuk, A. N.; Sidirenko, A. A.; Bountin, D. A.

2003-01-01

The topics of thermal anemometry and high-order spectral analyses were the subject of the technical training. Specifically, the objective of the technical training was to study: (i) the recently introduced constant voltage anemometer (CVA) for high-speed boundary layer; and (ii) newly developed high-order spectral analysis techniques (HOSA). Both CVA and HOSA are relevant tools for studies of boundary layer transition and stability.

Semiclassical spectral quantization: Application to two and four coupled molecular degrees of freedom

International Nuclear Information System (INIS)