Vibration damping method and apparatus
Redmond, James M.; Barney, Patrick S.; Parker, Gordon G.; Smith, David A.
1999-01-01
The present invention provides vibration damping method and apparatus that can damp vibration in more than one direction without requiring disassembly, that can accommodate varying tool dimensions without requiring re-tuning, and that does not interfere with tool tip operations and cooling. The present invention provides active dampening by generating bending moments internal to a structure such as a boring bar to dampen vibration thereof.
Reproducing Kernel Method for Solving Nonlinear Differential-Difference Equations
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Reza Mokhtari
2012-01-01
Full Text Available On the basis of reproducing kernel Hilbert spaces theory, an iterative algorithm for solving some nonlinear differential-difference equations (NDDEs is presented. The analytical solution is shown in a series form in a reproducing kernel space, and the approximate solution , is constructed by truncating the series to terms. The convergence of , to the analytical solution is also proved. Results obtained by the proposed method imply that it can be considered as a simple and accurate method for solving such differential-difference problems.
Aveiro method in reproducing kernel Hilbert spaces under complete dictionary
Mai, Weixiong; Qian, Tao
2017-12-01
Aveiro Method is a sparse representation method in reproducing kernel Hilbert spaces (RKHS) that gives orthogonal projections in linear combinations of reproducing kernels over uniqueness sets. It, however, suffers from determination of uniqueness sets in the underlying RKHS. In fact, in general spaces, uniqueness sets are not easy to be identified, let alone the convergence speed aspect with Aveiro Method. To avoid those difficulties we propose an anew Aveiro Method based on a dictionary and the matching pursuit idea. What we do, in fact, are more: The new Aveiro method will be in relation to the recently proposed, the so called Pre-Orthogonal Greedy Algorithm (P-OGA) involving completion of a given dictionary. The new method is called Aveiro Method Under Complete Dictionary (AMUCD). The complete dictionary consists of all directional derivatives of the underlying reproducing kernels. We show that, under the boundary vanishing condition, bring available for the classical Hardy and Paley-Wiener spaces, the complete dictionary enables an efficient expansion of any given element in the Hilbert space. The proposed method reveals new and advanced aspects in both the Aveiro Method and the greedy algorithm.
Cervical vertebrae maturation method morphologic criteria: poor reproducibility.
Nestman, Trenton S; Marshall, Steven D; Qian, Fang; Holton, Nathan; Franciscus, Robert G; Southard, Thomas E
2011-08-01
The cervical vertebrae maturation (CVM) method has been advocated as a predictor of peak mandibular growth. A careful review of the literature showed potential methodologic errors that might influence the high reported reproducibility of the CVM method, and we recently established that the reproducibility of the CVM method was poor when these potential errors were eliminated. The purpose of this study was to further investigate the reproducibility of the individual vertebral patterns. In other words, the purpose was to determine which of the individual CVM vertebral patterns could be classified reliably and which could not. Ten practicing orthodontists, trained in the CVM method, evaluated the morphology of cervical vertebrae C2 through C4 from 30 cephalometric radiographs using questions based on the CVM method. The Fleiss kappa statistic was used to assess interobserver agreement when evaluating each cervical vertebrae morphology question for each subject. The Kendall coefficient of concordance was used to assess the level of interobserver agreement when determining a "derived CVM stage" for each subject. Interobserver agreement was high for assessment of the lower borders of C2, C3, and C4 that were either flat or curved in the CVM method, but interobserver agreement was low for assessment of the vertebral bodies of C3 and C4 when they were either trapezoidal, rectangular horizontal, square, or rectangular vertical; this led to the overall poor reproducibility of the CVM method. These findings were reflected in the Fleiss kappa statistic. Furthermore, nearly 30% of the time, individual morphologic criteria could not be combined to generate a final CVM stage because of incompatible responses to the 5 questions. Intraobserver agreement in this study was only 62%, on average, when the inconclusive stagings were excluded as disagreements. Intraobserver agreement was worse (44%) when the inconclusive stagings were included as disagreements. For the group of subjects
Measurement System Analyses - Gauge Repeatability and Reproducibility Methods
Cepova, Lenka; Kovacikova, Andrea; Cep, Robert; Klaput, Pavel; Mizera, Ondrej
2018-02-01
The submitted article focuses on a detailed explanation of the average and range method (Automotive Industry Action Group, Measurement System Analysis approach) and of the honest Gauge Repeatability and Reproducibility method (Evaluating the Measurement Process approach). The measured data (thickness of plastic parts) were evaluated by both methods and their results were compared on the basis of numerical evaluation. Both methods were additionally compared and their advantages and disadvantages were discussed. One difference between both methods is the calculation of variation components. The AIAG method calculates the variation components based on standard deviation (then a sum of variation components does not give 100 %) and the honest GRR study calculates the variation components based on variance, where the sum of all variation components (part to part variation, EV & AV) gives the total variation of 100 %. Acceptance of both methods among the professional society, future use, and acceptance by manufacturing industry were also discussed. Nowadays, the AIAG is the leading method in the industry.
Methods for evaluating imaging methods of limited reproducibility
International Nuclear Information System (INIS)
Krummenauer, F.
2005-01-01
Just like new drugs, new or modified imaging methods must be subjected to objective clinical tests, including tests on humans. In this, it must be ensured that the principle of Good Clinical Practice (GCP) are followed with regard to medical, administrative and methodical quality. Innovative methods fo clinical epidemiology and medical biometry should be applied from the planning stage to the final statistical evaluation. The author presents established and new methods for planning, evaluation and reporting of clinical tests of diagnostic methods, and especially imaging methods, in clinical medicine and illustrates these by means of current research projects in the various medical disciplines. The strategies presented are summarized in a recommendation based on the concept of phases I - IV of clinical drug testing in order to enable standardisation of the clinical evaluation of imaging methods. (orig.)
Method and apparatus for vibrating a substrate during material formation
Bailey, Jeffrey A [Richland, WA; Roger, Johnson N [Richland, WA; John, Munley T [Benton City, WA; Walter, Park R [Benton City, WA
2008-10-21
A method and apparatus for affecting the properties of a material include vibrating the material during its formation (i.e., "surface sifting"). The method includes the steps of providing a material formation device and applying a plurality of vibrations to the material during formation, which vibrations are oscillations having dissimilar, non-harmonic frequencies and at least two different directions. The apparatus includes a plurality of vibration sources that impart vibrations to the material.
Leak detection by vibrational diagnostic methods
International Nuclear Information System (INIS)
Siklossy, P.
1983-01-01
The possibilities and methods of leak detection due to mechanical failures in nuclear power plants are reviewed on the basis of the literature. Great importance is attributed to vibrational diagnostic methods for their adventageous characteristics which enable them to become final leak detecting methods. The problems of noise analysis, e.g. leak detection by impact sound measurements, probe characteristics, gain problems, probe selection, off-line analysis and correlation functions, types of leak noises etc. are summarized. Leak detection based on noise analysis can be installed additionally to power plants. Its maintenance and testing is simple. On the other hand, it requires special training and measuring methods. (Sz.J.)
Soft and hard classification by reproducing kernel Hilbert space methods.
Wahba, Grace
2002-12-24
Reproducing kernel Hilbert space (RKHS) methods provide a unified context for solving a wide variety of statistical modelling and function estimation problems. We consider two such problems: We are given a training set [yi, ti, i = 1, em leader, n], where yi is the response for the ith subject, and ti is a vector of attributes for this subject. The value of y(i) is a label that indicates which category it came from. For the first problem, we wish to build a model from the training set that assigns to each t in an attribute domain of interest an estimate of the probability pj(t) that a (future) subject with attribute vector t is in category j. The second problem is in some sense less ambitious; it is to build a model that assigns to each t a label, which classifies a future subject with that t into one of the categories or possibly "none of the above." The approach to the first of these two problems discussed here is a special case of what is known as penalized likelihood estimation. The approach to the second problem is known as the support vector machine. We also note some alternate but closely related approaches to the second problem. These approaches are all obtained as solutions to optimization problems in RKHS. Many other problems, in particular the solution of ill-posed inverse problems, can be obtained as solutions to optimization problems in RKHS and are mentioned in passing. We caution the reader that although a large literature exists in all of these topics, in this inaugural article we are selectively highlighting work of the author, former students, and other collaborators.
Evaluation methods of vibration stress of small bore piping
Energy Technology Data Exchange (ETDEWEB)
Hiramatsu, Miki; Sasaki, Toru [Institute of Nuclear Safety System Inc., Mihama, Fukui (Japan)
2001-09-01
Fatigue fracture by vibration stress is one of the main causes of troubles which occur at small bore piping in nuclear power plants. Therefore at the plants they manage small bore piping using a method in which their vibration accelerations are measured and the vibration stresses are calculated. In this work, vibration tests for two sets of mock-ups simulating actual piping in the plants by sinusoidal oscillation and by that obtained at an actual plant were carried out, and then an evaluation method was developed to obtain proper value of vibration stress from the measured data by the vibration tests. In comparison of the vibration stress obtained from the measured acceleration with that directly measured using strain gauges, it is confirmed that accurate vibration stress can be evaluated by a formula in which the real center of gravity of small bore piping and the acceleration of main (system) piping are considered. (author)
Louraki, M; Tsentidis, C; Kallinikou, D; Katsalouli, M; Kanaka-Gantenbein, C; Kafassi, N; Papathanasiou, A; Karavanaki, K
2014-07-01
To define the reproducibility of vibration perception thresholds (VPTs) and the possible associated factors, as an early index of peripheral diabetic neuropathy (PDN) in type 1 diabetes mellitus (T1DM) children and adolescents. A single examiner studied 118 T1DM subjects (aged 13.5±3.4 years) and 79 controls (aged 12.0±3.07 years). Glycaemic control was assessed with HbA1c levels. VPT was measured twice on upper and lower limbs, using a Biothesiometer. Concordance between the two VPT measurements was evaluated using the Cohen's Weighted Kappa statistic (Kappa=0.41-0.60→moderate concordance, Kappa=0.61-0.80→substantial concordance). T1DM children had significantly higher VPTs than controls at all sites (p=0.001), but with lower Kappa values (0.64-0.70). VPT values increased in parallel with HbA1c (a.9.5%) and T1DM duration (a.1-10, c.>10 years). However, Kappa values were lower in the groups with the poorest control (HbA1c>9.5%) (Kappa=0.54-0.76) or the longest T1DM duration (>10 years) (Kappa=0.49-0.71). Although VPTs increased with stature and male gender, no effect on VPT reproducibility was observed. However, obesity was associated with lower VPT values and poorer concordance. These findings suggest that the reproducibility of VPTs is lower in the high-risk patients for early subclinical PDN development, who need a regular follow-up. Copyright © 2013 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.
Reactor internals vibration monitoring by neutron noise methods in PWRs
International Nuclear Information System (INIS)
Pazsit, I.; Por, G.; Lux, I.
1983-01-01
Certain elements of PWR cores such as control/fuel rods or cassettes, or other parts of reactor internals, often represent a vibration problem. Early analyses at operating PWR plant revealed that these vibrations can be detected by in-core neutron detectors, opening up the possibility of vibration monitoring and diagnostics by noise methods. Theoretical methods of calculating vibration induced neutron noise and its application to vibration diagnostics are summarized. Experiments to check theoretical conclusions are under way at the Central Research Institute for Physics, Budapest. (author)
Analysis of Vibration Diagnostics Methods for Induction Motors
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A. P. Kalinov
2012-01-01
Full Text Available The paper presents an analysis of existing vibration diagnostics methods. In order to evaluate an efficiency of method application the following criteria have been proposed: volume of input data required for establishing diagnosis, data content, software and hardware level, execution time for vibration diagnostics. According to the mentioned criteria a classification of vibration diagnostics methods for determination of their advantages and disadvantages, search for their development and improvement has been presented in paper. The paper contains a comparative estimation of methods in accordance with the proposed criteria. According to this estimation the most efficient methods are a spectral analysis and spectral analysis of the vibration signal envelope.
Methods of performing downhole operations using orbital vibrator energy sources
Cole, Jack H.; Weinberg, David M.; Wilson, Dennis R.
2004-02-17
Methods of performing down hole operations in a wellbore. A vibrational source is positioned within a tubular member such that an annulus is formed between the vibrational source and an interior surface of the tubular member. A fluid medium, such as high bulk modulus drilling mud, is disposed within the annulus. The vibrational source forms a fluid coupling with the tubular member through the fluid medium to transfer vibrational energy to the tubular member. The vibrational energy may be used, for example, to free a stuck tubular, consolidate a cement slurry and/or detect voids within a cement slurry prior to the curing thereof.
Apparatus and method for vibrating a casing string during cementing
International Nuclear Information System (INIS)
Rankin, R.E.; Rankin, K.T.
1992-01-01
This patent describes a method of cementing a string of casing in a well. It comprises: securing a vibrating device into the string of casing near the lower end of the string of casing; lowering the string of casing into the well to the desired depth; pumping a cement slurry down the string of casing; causing a portion of the cement slurry being pumped down the string of casing to vibrate the vibrating device; and wherein the vibrating device is secured in the string of casing by cementing the vibrating device within a sub, then securing the sub into the string of casing prior to lowering the string of casing into the well
THz-SAR Vibrating Target Imaging via the Bayesian Method
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Bin Deng
2017-01-01
Full Text Available Target vibration bears important information for target recognition, and terahertz, due to significant micro-Doppler effects, has strong advantages for remotely sensing vibrations. In this paper, the imaging characteristics of vibrating targets with THz-SAR are at first analyzed. An improved algorithm based on an excellent Bayesian approach, that is, the expansion-compression variance-component (ExCoV method, has been proposed for reconstructing scattering coefficients of vibrating targets, which provides more robust and efficient initialization and overcomes the deficiencies of sidelobes as well as artifacts arising from the traditional correlation method. A real vibration measurement experiment of idle cars was performed to validate the range model. Simulated SAR data of vibrating targets and a tank model in a real background in 220 GHz show good performance at low SNR. Rapidly evolving high-power terahertz devices will offer viable THz-SAR application at a distance of several kilometers.
Corneal Vibrations during Intraocular Pressure Measurement with an Air-Puff Method
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Robert Koprowski
2018-01-01
Full Text Available Introduction. The paper presents a commentary on the method of analysis of corneal vibrations occurring during eye pressure measurements with air-puff tonometers, for example, Corvis. The presented definition and measurement method allow for the analysis of image sequences of eye responses—cornea deformation. In particular, the outer corneal contour and sclera fragments are analysed, and 3D reconstruction is performed. Methods. On this basis, well-known parameters such as eyeball reaction or corneal response are determined. The next steps of analysis allow for automatic and reproducible separation of four different corneal vibrations. These vibrations are associated with (1 the location of the maximum of cornea deformation; (2 the cutoff area measured in relation to the cornea in a steady state; (3 the maximum of peaks occurring between applanations; and (4 the other characteristic points of the corneal contour. Results. The results obtained enable (1 automatic determination of the amplitude of vibrations; (2 determination of the frequency of vibrations; and (3 determination of the correlation between the selected types of vibrations. Conclusions. These are diagnostic features that can be directly applied clinically for new and archived data.
International Nuclear Information System (INIS)
Ohura, Hirotaka; Wakabayashi, Genichiro; Nakamura, Kouji; Okai, Tomio; Matoba, Masaru; Kakiuchi, Hideki; Momoshima, Noriyuki; Kawamura, Hidehisa.
1997-01-01
Simple liquid scintillation counting technique for the assay of 14 C in the environment was developed. This technique was done by using gel suspension method, in which sample preparation is very simple and requires no special equipments. The reproducibility of this technique was considered and it was shown that the gel suspension method had enough reproducibility to monitor the environmental 14 C. (author)
Heart rate-based lactate minimum test: a reproducible method.
Strupler, M.; Muller, G.; Perret, C.
2009-01-01
OBJECTIVE: To find the individual intensity for aerobic endurance training, the lactate minimum test (LMT) seems to be a promising method. LMTs described in the literature consist of speed or work rate-based protocols, but for training prescription in daily practice mostly heart rate is used. The
Standardized method for reproducing the sequential X-rays flap
International Nuclear Information System (INIS)
Brenes, Alejandra; Molina, Katherine; Gudino, Sylvia
2009-01-01
A method is validated to estandardize in the taking, developing and analysis of bite-wing radiographs taken in sequential way, in order to compare and evaluate detectable changes in the evolution of the interproximal lesions through time. A radiographic positioner called XCP® is modified by means of a rigid acrylic guide, to achieve proper of the X ray equipment core positioning relative to the XCP® ring and the reorientation during the sequential x-rays process. 16 subjects of 4 to 40 years old are studied for a total number of 32 registries. Two x-rays of the same block of teeth of each subject have been taken in sequential way, with a minimal difference of 30 minutes between each one, before the placement of radiographic attachment. The images have been digitized with a Super Cam® scanner and imported to a software. The measurements in X and Y-axis for both x-rays were performed to proceed to compare. The intraclass correlation index (ICI) has shown that the proposed method is statistically related to measurement (mm) obtained in the X and Y-axis for both sequential series of x-rays (p=0.01). The measures of central tendency and dispersion have shown that the usual occurrence is indifferent between the two measurements (Mode 0.000 and S = 0083 and 0.109) and that the probability of occurrence of different values is lower than expected. (author) [es
Reproducibility Between Brain Uptake Ratio Using Anatomic Standardization and Patlak-Plot Methods.
Shibutani, Takayuki; Onoguchi, Masahisa; Noguchi, Atsushi; Yamada, Tomoki; Tsuchihashi, Hiroko; Nakajima, Tadashi; Kinuya, Seigo
2015-12-01
The Patlak-plot and conventional methods of determining brain uptake ratio (BUR) have some problems with reproducibility. We formulated a method of determining BUR using anatomic standardization (BUR-AS) in a statistical parametric mapping algorithm to improve reproducibility. The objective of this study was to demonstrate the inter- and intraoperator reproducibility of mean cerebral blood flow as determined using BUR-AS in comparison to the conventional-BUR (BUR-C) and Patlak-plot methods. The images of 30 patients who underwent brain perfusion SPECT were retrospectively used in this study. The images were reconstructed using ordered-subset expectation maximization and processed using an automatic quantitative analysis for cerebral blood flow of ECD tool. The mean SPECT count was calculated from axial basal ganglia slices of the normal side (slices 31-40) drawn using a 3-dimensional stereotactic region-of-interest template after anatomic standardization. The mean cerebral blood flow was calculated from the mean SPECT count. Reproducibility was evaluated using coefficient of variation and Bland-Altman plotting. For both inter- and intraoperator reproducibility, the BUR-AS method had the lowest coefficient of variation and smallest error range about the Bland-Altman plot. Mean CBF obtained using the BUR-AS method had the highest reproducibility. Compared with the Patlak-plot and BUR-C methods, the BUR-AS method provides greater inter- and intraoperator reproducibility of cerebral blood flow measurement. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.
METHOD FOR DETERMINATION OF ROTATION CENTER IN VIBRATING OBJECT
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I. P. Kauryha
2016-01-01
Full Text Available Linear piezoelectric gauges, eddy current transducers and other control and measuring devices have been widely applied for vibration diagnostics of objects in industry. Methods based on such gauges and used for measuring angular and linear vibrations do not provide the possibility to assess a rotation center or point angle of an object. Parasitic oscillations may occur during rotor rotation and in some cases the oscillations are caused by dis-balance. The known methods for measuring angular and linear vibrations make it possible to detect the phenomenon and they do not provide information for balancing of the given object. For this very reason the paper describes a method for obtaining instantaneous rotation center in the vibrating object. It allows to improve informational content of the measurements owing to obtaining additional data on position of object rotation center. The obtained data can be used for balancing of a control object. Essence of the given method is shown by an example of piezoelectric gauges of linear vibrations. Two three-axial gauges are fixed to the investigated object. Then gauge output signals are recalculated in angular vibrations of the object (for this purpose it is necessary to know a distance between gauges. Further projection positions of the object rotation center are determined on three orthogonal planes. Instantaneous rotation center is calculated according to the position of one of the gauges. The proposed method permits to obtain data on linear and angular vibrations and rotation center position of the vibrating object using one system of linear gauge. Possibilities of object diagnostics are expanded due to increase in number of determined parameters pertaining to object moving. The method also makes it possible to reduce material and time expenses for measurement of an angular vibration component.
CHECKING OF TECHNICAL BRIDGES’ STATE BY PASSIVE VIBRATIONAL DYNAMICS METHODS
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V. P. Redchenko
2010-03-01
Full Text Available In the article the results of studies of the passive vibration test methods and the possibilities of using them for determining and monitoring of technical condition of bridges are presented.
A vibration correction method for free-fall absolute gravimeters
Qian, J.; Wang, G.; Wu, K.; Wang, L. J.
2018-02-01
An accurate determination of gravitational acceleration, usually approximated as 9.8 m s-2, has been playing an important role in the areas of metrology, geophysics, and geodetics. Absolute gravimetry has been experiencing rapid developments in recent years. Most absolute gravimeters today employ a free-fall method to measure gravitational acceleration. Noise from ground vibration has become one of the most serious factors limiting measurement precision. Compared to vibration isolators, the vibration correction method is a simple and feasible way to reduce the influence of ground vibrations. A modified vibration correction method is proposed and demonstrated. A two-dimensional golden section search algorithm is used to search for the best parameters of the hypothetical transfer function. Experiments using a T-1 absolute gravimeter are performed. It is verified that for an identical group of drop data, the modified method proposed in this paper can achieve better correction effects with much less computation than previous methods. Compared to vibration isolators, the correction method applies to more hostile environments and even dynamic platforms, and is expected to be used in a wider range of applications.
Measurement of food texture by an acoustic vibration method
Sakurai, Naoki; Taniwaki, Mitsuru; Iwatani, Shin-ichiro; Akimoto, Hidemi
2011-09-01
Food texture was measured by a new acoustic vibration method. A piezoelectric sensor sandwiched between a probe and piston was inserted into a food sample by delivery of silicon oil to a cylinder by a pump. Vibration emitted from the food sample on insertion of the probe was monitored by voltage outputs of the sensor. The voltage signals were passed through 19 half octave bands to calculate texture index for each band. The texture index was defined as vibration energy of the probe caused by the food rupture and/or breakage per unit time.
Blasting vibrations control: The shortcomings of traditional methods
Energy Technology Data Exchange (ETDEWEB)
Vuillaume, P.M.; Kiszlo, M. [Institut National de l`Environnement Industriel et des Risques, Verneuil en Halatte (France); Bernard, T. [Compagnie Nouvelle de Scientifiques, Nice (France)
1996-12-31
In the context of its studies for the French ministry of the environment and for the French national coal board, INERIS (the French institute for the industrial environment and hazards, formerly CERCHAR) has made a complete critical survey of the methods generally used to reduce the levels of blasting vibrations. It is generally acknowledged that the main parameter to control vibrations is the so-called instantaneous charge, or charge per delay. This should be reduced as much as possible in order to diminish vibration levels. On account of this, the use of a new generation of blasting devices, such as non-electric detonators or electronic sequential timers has been developed since the seventies. INERIS has collected data from about 900 blasts in 2 quarries and 3 open pit mines. These data include input parameters such as borehole diameter, burden, spacing, charge per hole, charge per delay, total fired charge, etc ... They also include output measurements, such as vibration peak particle velocities, and main frequencies. These data have been analyzed with the help of multi variable statistical tools. Blasting tests were undertaken to evaluate new methods of vibrations control, such as the superposition of vibration signals. These methods appear to be accurate in many critical cases, but certainly would be highly improved with a better accuracy of firing delays. The development of electronic detonators seems to be the way of the future for a better blasting control.
Efficient forced vibration reanalysis method for rotating electric machines
Saito, Akira; Suzuki, Hiromitsu; Kuroishi, Masakatsu; Nakai, Hideo
2015-01-01
Rotating electric machines are subject to forced vibration by magnetic force excitation with wide-band frequency spectrum that are dependent on the operating conditions. Therefore, when designing the electric machines, it is inevitable to compute the vibration response of the machines at various operating conditions efficiently and accurately. This paper presents an efficient frequency-domain vibration analysis method for the electric machines. The method enables the efficient re-analysis of the vibration response of electric machines at various operating conditions without the necessity to re-compute the harmonic response by finite element analyses. Theoretical background of the proposed method is provided, which is based on the modal reduction of the magnetic force excitation by a set of amplitude-modulated standing-waves. The method is applied to the forced response vibration of the interior permanent magnet motor at a fixed operating condition. The results computed by the proposed method agree very well with those computed by the conventional harmonic response analysis by the FEA. The proposed method is then applied to the spin-up test condition to demonstrate its applicability to various operating conditions. It is observed that the proposed method can successfully be applied to the spin-up test conditions, and the measured dominant frequency peaks in the frequency response can be well captured by the proposed approach.
Directory of Open Access Journals (Sweden)
Akgül Ali
2016-01-01
Full Text Available In this manuscript we investigate electrodynamic flow. For several values of the intimate parameters we proved that the approximate solution depends on a reproducing kernel model. Obtained results prove that the reproducing kernel method (RKM is very effective. We obtain good results without any transformation or discretization. Numerical experiments on test examples show that our proposed schemes are of high accuracy and strongly support the theoretical results.
Reducing vibration transfer from power plants by active methods
Kiryukhin, A. V.; Milman, O. O.; Ptakhin, A. V.
2017-12-01
The possibility of applying the methods of active damping of vibration and pressure pulsations for reducing their transfer from power plants into the environment, the seating, and the industrial premises are considered. The results of experimental works implemented by the authors on the active broadband damping of vibration and dynamic forces after shock-absorption up to 15 dB in the frequency band up to 150 Hz, of water pressure pulsations in the pipeline up to 20 dB in the frequency band up to 600 Hz, and of spatial low-frequency air noise indoors of a diesel generator at discrete frequency up to 20 dB are presented. It is shown that a reduction of vibration transfer through a vibration-isolating junction (expansion joints) of pipelines with liquid is the most complicated and has hardly been developed so far. This problem is essential for vibration isolation of power equipment from the seating and the environment through pipelines with water and steam in the power and transport engineering, shipbuilding, and in oil and gas pipelines in pumping stations. For improving efficiency, reducing the energy consumption, and decreasing the overall dimensions of equipment, it is advisable to combine the work of an active system with passive damping means, the use of which is not always sufficient. The executive component of the systems of active damping should be placed behind the vibration isolators (expansion joints). It is shown that the existence of working medium and connection of vibration with pressure pulsations in existing designs of pipeline expansion joints lead to growth of vibration stiffness of the expansion joint with the environment by two and more orders as compared with the static stiffness and makes difficulties for using the active methods. For active damping of vibration transfer through expansion joints of pipelines with a liquid, it is necessary to develop expansion joint structures with minimal connection of vibrations and pulsations and minimal
Vibration of carbon nanotubes with defects: order reduction methods
Hudson, Robert B.; Sinha, Alok
2018-03-01
Order reduction methods are widely used to reduce computational effort when calculating the impact of defects on the vibrational properties of nearly periodic structures in engineering applications, such as a gas-turbine bladed disc. However, despite obvious similarities these techniques have not yet been adapted for use in analysing atomic structures with inevitable defects. Two order reduction techniques, modal domain analysis and modified modal domain analysis, are successfully used in this paper to examine the changes in vibrational frequencies, mode shapes and mode localization caused by defects in carbon nanotubes. The defects considered are isotope defects and Stone-Wales defects, though the methods described can be extended to other defects.
Laser method of acoustical emission control from vibrating surfaces
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.
Reproducing kernel method with Taylor expansion for linear Volterra integro-differential equations
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Azizallah Alvandi
2017-06-01
Full Text Available This research aims of the present a new and single algorithm for linear integro-differential equations (LIDE. To apply the reproducing Hilbert kernel method, there is made an equivalent transformation by using Taylor series for solving LIDEs. Shown in series form is the analytical solution in the reproducing kernel space and the approximate solution $ u_{N} $ is constructed by truncating the series to $ N $ terms. It is easy to prove the convergence of $ u_{N} $ to the analytical solution. The numerical solutions from the proposed method indicate that this approach can be implemented easily which shows attractive features.
Enriched reproducing kernel particle method for fractional advection-diffusion equation
Ying, Yuping; Lian, Yanping; Tang, Shaoqiang; Liu, Wing Kam
2018-06-01
The reproducing kernel particle method (RKPM) has been efficiently applied to problems with large deformations, high gradients and high modal density. In this paper, it is extended to solve a nonlocal problem modeled by a fractional advection-diffusion equation (FADE), which exhibits a boundary layer with low regularity. We formulate this method on a moving least-square approach. Via the enrichment of fractional-order power functions to the traditional integer-order basis for RKPM, leading terms of the solution to the FADE can be exactly reproduced, which guarantees a good approximation to the boundary layer. Numerical tests are performed to verify the proposed approach.
International Nuclear Information System (INIS)
Perotin, L.; Granger, S.
1997-01-01
In order to improve the prediction of wear problems due to flow-induced vibration in PWR components, an inverse method for identifying a distributed random excitation acting on a dynamical system has been developed at EDF. This method, whose applications go far beyond the flow-induced vibration field, has been implemented into the MEIDEE software. This method is presented. (author)
Recent development of the passive vibration control method
Ishida, Yukio
2012-05-01
This paper introduces new passive vibration suppression methods developed recently in our laboratory. First, two methods used to suppress steady-state resonances are explained. One is the improvement of the efficiency of a ball balancer. A simple method to eliminate the influence of friction of balls and to improve its efficiency is introduced. The other is an effective method that utilizes the discontinuous spring characteristics. Secondly, a method to eliminate unstable ranges in rotor systems is explained. Unstable ranges in an asymmetrical shaft, and in a hollow rotor partially filled with liquid, are eliminated by the discontinuous spring characteristics. Thirdly, a method to suppress self-excited oscillations is explained. Self-excited oscillations due to internal damping and rubbing are discussed. Finally, the methods of using a pendulum or roller type absorbers to suppress torsional vibrations are explained.
Comparison of vibrational conductivity and radiative energy transfer methods
Le Bot, A.
2005-05-01
This paper is concerned with the comparison of two methods well suited for the prediction of the wideband response of built-up structures subjected to high-frequency vibrational excitation. The first method is sometimes called the vibrational conductivity method and the second one is rather known as the radiosity method in the field of acoustics, or the radiative energy transfer method. Both are based on quite similar physical assumptions i.e. uncorrelated sources, mean response and high-frequency excitation. Both are based on analogies with some equations encountered in the field of heat transfer. However these models do not lead to similar results. This paper compares the two methods. Some numerical simulations on a pair of plates joined along one edge are provided to illustrate the discussion.
Energy Technology Data Exchange (ETDEWEB)
Clabo, D.A. Jr.
1987-04-01
Inclusion of the anharmonicity normal mode vibrations (i.e., the third and fourth (and higher) derivatives of a molecular Born-Oppenheimer potential energy surface) is necessary in order to theoretically reproduce experimental fundamental vibrational frequencies of a molecule. Although ab initio determinations of harmonic vibrational frequencies may give errors of only a few percent by the inclusion of electron correlation within a large basis set for small molecules, in general, molecular fundamental vibrational frequencies are more often available from high resolution vibration-rotation spectra. Recently developed analytic third derivatives methods for self-consistent-field (SCF) wavefunctions have made it possible to examine with previously unavailable accuracy and computational efficiency the anharmonic force fields of small molecules.
International Nuclear Information System (INIS)
Clabo, D.A. Jr.
1987-04-01
Inclusion of the anharmonicity normal mode vibrations [i.e., the third and fourth (and higher) derivatives of a molecular Born-Oppenheimer potential energy surface] is necessary in order to theoretically reproduce experimental fundamental vibrational frequencies of a molecule. Although ab initio determinations of harmonic vibrational frequencies may give errors of only a few percent by the inclusion of electron correlation within a large basis set for small molecules, in general, molecular fundamental vibrational frequencies are more often available from high resolution vibration-rotation spectra. Recently developed analytic third derivatives methods for self-consistent-field (SCF) wavefunctions have made it possible to examine with previously unavailable accuracy and computational efficiency the anharmonic force fields of small molecules
Directory of Open Access Journals (Sweden)
Omar Abu Arqub
2012-01-01
Full Text Available This paper investigates the numerical solution of nonlinear Fredholm-Volterra integro-differential equations using reproducing kernel Hilbert space method. The solution ( is represented in the form of series in the reproducing kernel space. In the mean time, the n-term approximate solution ( is obtained and it is proved to converge to the exact solution (. Furthermore, the proposed method has an advantage that it is possible to pick any point in the interval of integration and as well the approximate solution and its derivative will be applicable. Numerical examples are included to demonstrate the accuracy and applicability of the presented technique. The results reveal that the method is very effective and simple.
Azuaje, Francisco; Zheng, Huiru; Camargo, Anyela; Wang, Haiying
2011-08-01
The discovery of novel disease biomarkers is a crucial challenge for translational bioinformatics. Demonstration of both their classification power and reproducibility across independent datasets are essential requirements to assess their potential clinical relevance. Small datasets and multiplicity of putative biomarker sets may explain lack of predictive reproducibility. Studies based on pathway-driven discovery approaches have suggested that, despite such discrepancies, the resulting putative biomarkers tend to be implicated in common biological processes. Investigations of this problem have been mainly focused on datasets derived from cancer research. We investigated the predictive and functional concordance of five methods for discovering putative biomarkers in four independently-generated datasets from the cardiovascular disease domain. A diversity of biosignatures was identified by the different methods. However, we found strong biological process concordance between them, especially in the case of methods based on gene set analysis. With a few exceptions, we observed lack of classification reproducibility using independent datasets. Partial overlaps between our putative sets of biomarkers and the primary studies exist. Despite the observed limitations, pathway-driven or gene set analysis can predict potentially novel biomarkers and can jointly point to biomedically-relevant underlying molecular mechanisms. Copyright © 2011 Elsevier Inc. All rights reserved.
DEFF Research Database (Denmark)
Madsen, Lone; Dalsgaard, Inger
1999-01-01
, and this method was tested using isolates with different elastin- degrading profiles and representing different serotypes. Injecting trout, average weight 1 g, with 10(4) CFU (colony- forming units) per fish caused cumulative mortalities around 60 to 70%. The virulent strains belonged to certain serotypes...... and degraded elastin. The intraperitoneal injection challenge method could be used on larger fish, but the infection dose was 10(7) CFU per fish before mortalities occurred. Bath infection and bath infection in combination with formalin treatment (stress) seemed to be reproducible methods that could be used...
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.
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.)
A reproducible accelerated in vitro release testing method for PLGA microspheres.
Shen, Jie; Lee, Kyulim; Choi, Stephanie; Qu, Wen; Wang, Yan; Burgess, Diane J
2016-02-10
The objective of the present study was to develop a discriminatory and reproducible accelerated in vitro release method for long-acting PLGA microspheres with inner structure/porosity differences. Risperidone was chosen as a model drug. Qualitatively and quantitatively equivalent PLGA microspheres with different inner structure/porosity were obtained using different manufacturing processes. Physicochemical properties as well as degradation profiles of the prepared microspheres were investigated. Furthermore, in vitro release testing of the prepared risperidone microspheres was performed using the most common in vitro release methods (i.e., sample-and-separate and flow through) for this type of product. The obtained compositionally equivalent risperidone microspheres had similar drug loading but different inner structure/porosity. When microsphere particle size appeared similar, porous risperidone microspheres showed faster microsphere degradation and drug release compared with less porous microspheres. Both in vitro release methods investigated were able to differentiate risperidone microsphere formulations with differences in porosity under real-time (37 °C) and accelerated (45 °C) testing conditions. Notably, only the accelerated USP apparatus 4 method showed good reproducibility for highly porous risperidone microspheres. These results indicated that the accelerated USP apparatus 4 method is an appropriate fast quality control tool for long-acting PLGA microspheres (even with porous structures). Copyright © 2015 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Wang, Wenyan; Han, Bo; Yamamoto, Masahiro
2013-01-01
We propose a new numerical method for reproducing kernel Hilbert space to solve an inverse source problem for a two-dimensional fractional diffusion equation, where we are required to determine an x-dependent function in a source term by data at the final time. The exact solution is represented in the form of a series and the approximation solution is obtained by truncating the series. Furthermore, a technique is proposed to improve some of the existing methods. We prove that the numerical method is convergent under an a priori assumption of the regularity of solutions. The method is simple to implement. Our numerical result shows that our method is effective and that it is robust against noise in L 2 -space in reconstructing a source function. (paper)
A simple optical method for measuring the vibration amplitude of a speaker
UEDA, Masahiro; YAMAGUCHI, Toshihiko; KAKIUCHI, Hiroki; SUGA, Hiroshi
1999-01-01
A simple optical method has been proposed for measuring the vibration amplitude of a speaker vibrating with a frequency of approximately 10 kHz. The method is based on a multiple reflection between a vibrating speaker plane and a mirror parallel to that speaker plane. The multiple reflection can magnify a dispersion of the laser beam caused by the vibration, and easily make a measurement of the amplitude. The measuring sensitivity ranges between sub-microns and 1 mm. A preliminary experim...
Vibration analysis of pipes conveying fluid by transfer matrix method
International Nuclear Information System (INIS)
Li, Shuai-jun; Liu, Gong-min; Kong, Wei-tao
2014-01-01
Highlights: • A theoretical study on vibration analysis of pipes with FSI is presented. • Pipelines with high fluid pressure and velocity can be solved by developed method. • Several pipeline schemes are discussed to illustrate the application of the method. • The proposed method is easier to apply compared to most existing procedures. • Influence laws of structural and fluid parameters on FSI of pipe are analyzed. -- Abstract: Considering the effects of pipe wall thickness, fluid pressure and velocity, a developed 14-equation model is presented, which describes the fluid–structure interaction behavior of pipelines. The transfer matrix method has been used for numerical modeling of both hydraulic and structural equations. Based on these models and algorithms, several pipeline schemes are presented to illustrate the application of the proposed method. Furthermore, the influence laws of supports, structural properties and fluid parameters on the dynamic response and natural frequencies of pipeline are analyzed, which shows using the optimal supports and structural properties is beneficial to reduce vibration of pipelines
Method for pulse to pulse dose reproducibility applied to electron linear accelerators
International Nuclear Information System (INIS)
Ighigeanu, D.; Martin, D.; Oproiu, C.; Cirstea, E.; Craciun, G.
2002-01-01
An original method for obtaining programmed beam single shots and pulse trains with programmed pulse number, pulse repetition frequency, pulse duration and pulse dose is presented. It is particularly useful for automatic control of absorbed dose rate level, irradiation process control as well as in pulse radiolysis studies, single pulse dose measurement or for research experiments where pulse-to-pulse dose reproducibility is required. This method is applied to the electron linear accelerators, ALIN-10 of 6.23 MeV and 82 W and ALID-7, of 5.5 MeV and 670 W, built in NILPRP. In order to implement this method, the accelerator triggering system (ATS) consists of two branches: the gun branch and the magnetron branch. ATS, which synchronizes all the system units, delivers trigger pulses at a programmed repetition rate (up to 250 pulses/s) to the gun (80 kV, 10 A and 4 ms) and magnetron (45 kV, 100 A, and 4 ms).The accelerated electron beam existence is determined by the electron gun and magnetron pulses overlapping. The method consists in controlling the overlapping of pulses in order to deliver the beam in the desired sequence. This control is implemented by a discrete pulse position modulation of gun and/or magnetron pulses. The instabilities of the gun and magnetron transient regimes are avoided by operating the accelerator with no accelerated beam for a certain time. At the operator 'beam start' command, the ATS controls electron gun and magnetron pulses overlapping and the linac beam is generated. The pulse-to-pulse absorbed dose variation is thus considerably reduced. Programmed absorbed dose, irradiation time, beam pulse number or other external events may interrupt the coincidence between the gun and magnetron pulses. Slow absorbed dose variation is compensated by the control of the pulse duration and repetition frequency. Two methods are reported in the electron linear accelerators' development for obtaining the pulse to pulse dose reproducibility: the method
Comparison of methods for separating vibration sources in rotating machinery
Klein, Renata
2017-12-01
Vibro-acoustic signatures are widely used for diagnostics of rotating machinery. Vibration based automatic diagnostics systems need to achieve a good separation between signals generated by different sources. The separation task may be challenging, since the effects of the different vibration sources often overlap. In particular, there is a need to separate between signals related to the natural frequencies of the structure and signals resulting from the rotating components (signal whitening), as well as a need to separate between signals generated by asynchronous components like bearings and signals generated by cyclo-stationary components like gears. Several methods were proposed to achieve the above separation tasks. The present study compares between some of these methods. The paper also presents a new method for whitening, Adaptive Clutter Separation, as well as a new efficient algorithm for dephase, which separates between asynchronous and cyclo-stationary signals. For whitening the study compares between liftering of the high quefrencies and adaptive clutter separation. For separating between the asynchronous and the cyclo-stationary signals the study compares between liftering in the quefrency domain and dephase. The methods are compared using both simulated signals and real data.
Satellite Vibration Testing: Angle optimisation method to Reduce Overtesting
Knight, Charly; Remedia, Marcello; Aglietti, Guglielmo S.; Richardson, Guy
2018-06-01
Spacecraft overtesting is a long running problem, and the main focus of most attempts to reduce it has been to adjust the base vibration input (i.e. notching). Instead this paper examines testing alternatives for secondary structures (equipment) coupled to the main structure (satellite) when they are tested separately. Even if the vibration source is applied along one of the orthogonal axes at the base of the coupled system (satellite plus equipment), the dynamics of the system and potentially the interface configuration mean the vibration at the interface may not occur all along one axis much less the corresponding orthogonal axis of the base excitation. This paper proposes an alternative testing methodology in which the testing of a piece of equipment occurs at an offset angle. This Angle Optimisation method may have multiple tests but each with an altered input direction allowing for the best match between all specified equipment system responses with coupled system tests. An optimisation process that compares the calculated equipment RMS values for a range of inputs with the maximum coupled system RMS values, and is used to find the optimal testing configuration for the given parameters. A case study was performed to find the best testing angles to match the acceleration responses of the centre of mass and sum of interface forces for all three axes, as well as the von Mises stress for an element by a fastening point. The angle optimisation method resulted in RMS values and PSD responses that were much closer to the coupled system when compared with traditional testing. The optimum testing configuration resulted in an overall average error significantly smaller than the traditional method. Crucially, this case study shows that the optimum test campaign could be a single equipment level test opposed to the traditional three orthogonal direction tests.
A method to reproduce alpha-particle spectra measured with semiconductor detectors.
Timón, A Fernández; Vargas, M Jurado; Sánchez, A Martín
2010-01-01
A method is proposed to reproduce alpha-particle spectra measured with silicon detectors, combining analytical and computer simulation techniques. The procedure includes the use of the Monte Carlo method to simulate the tracks of alpha-particles within the source and in the detector entrance window. The alpha-particle spectrum is finally obtained by the convolution of this simulated distribution and the theoretical distributions representing the contributions of the alpha-particle spectrometer to the spectrum. Experimental spectra from (233)U and (241)Am sources were compared with the predictions given by the proposed procedure, showing good agreement. The proposed method can be an important aid for the analysis and deconvolution of complex alpha-particle spectra. Copyright 2009 Elsevier Ltd. All rights reserved.
Non-coding RNA detection methods combined to improve usability, reproducibility and precision
Directory of Open Access Journals (Sweden)
Kreikemeyer Bernd
2010-09-01
Full Text Available Abstract Background Non-coding RNAs gain more attention as their diverse roles in many cellular processes are discovered. At the same time, the need for efficient computational prediction of ncRNAs increases with the pace of sequencing technology. Existing tools are based on various approaches and techniques, but none of them provides a reliable ncRNA detector yet. Consequently, a natural approach is to combine existing tools. Due to a lack of standard input and output formats combination and comparison of existing tools is difficult. Also, for genomic scans they often need to be incorporated in detection workflows using custom scripts, which decreases transparency and reproducibility. Results We developed a Java-based framework to integrate existing tools and methods for ncRNA detection. This framework enables users to construct transparent detection workflows and to combine and compare different methods efficiently. We demonstrate the effectiveness of combining detection methods in case studies with the small genomes of Escherichia coli, Listeria monocytogenes and Streptococcus pyogenes. With the combined method, we gained 10% to 20% precision for sensitivities from 30% to 80%. Further, we investigated Streptococcus pyogenes for novel ncRNAs. Using multiple methods--integrated by our framework--we determined four highly probable candidates. We verified all four candidates experimentally using RT-PCR. Conclusions We have created an extensible framework for practical, transparent and reproducible combination and comparison of ncRNA detection methods. We have proven the effectiveness of this approach in tests and by guiding experiments to find new ncRNAs. The software is freely available under the GNU General Public License (GPL, version 3 at http://www.sbi.uni-rostock.de/moses along with source code, screen shots, examples and tutorial material.
A Vibration Control Method for the Flexible Arm Based on Energy Migration
Directory of Open Access Journals (Sweden)
Yushu Bian
2015-01-01
Full Text Available A vibration control method based on energy migration is proposed to decrease vibration response of the flexible arm undergoing rigid motion. A type of vibration absorber is suggested and gives rise to the inertial coupling between the modes of the flexible arm and the absorber. By analyzing 1 : 2 internal resonance, it is proved that the internal resonance can be successfully created and the exchange of vibration energy is existent. Due to the inertial coupling, the damping enhancement effect is revealed. Via the inertial coupling, vibration energy of the flexible arm can be dissipated by not only the damping of the vibration absorber but also its own enhanced damping, thereby effectively decreasing vibration. Through numerical simulations and analyses, it is proven that this method is feasible in controlling nonlinear vibration of the flexible arm undergoing rigid motion.
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.
Manuel, Sharrón L; Johnson, Brian W; Frevert, Charles W; Duncan, Francesca E
2018-04-21
Immunohistochemistry (IHC) is a robust scientific tool whereby cellular components are visualized within a tissue, and this method has been and continues to be a mainstay for many reproductive biologists. IHC is highly informative if performed and interpreted correctly, but studies have shown that the general use and reporting of appropriate controls in IHC experiments is low. This omission of the scientific method can result in data that lacks rigor and reproducibility. In this editorial, we highlight key concepts in IHC controls and describe an opportunity for our field to partner with the Histochemical Society to adopt their IHC guidelines broadly as researchers, authors, ad hoc reviewers, editorial board members, and editors-in-chief. Such cross-professional society interactions will ensure that we produce the highest quality data as new technologies emerge that still rely upon the foundations of classic histological and immunohistochemical principles.
A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones
Directory of Open Access Journals (Sweden)
Yongmeng Zhang
2015-01-01
Full Text Available Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.
Directory of Open Access Journals (Sweden)
Daniela Camargos Costa
2014-02-01
Full Text Available The polymerase chain reaction (PCR-based methods for the diagnosis of malaria infection are expected to accurately identify submicroscopic parasite carriers. Although a significant number of PCR protocols have been described, few studies have addressed the performance of PCR amplification in cases of field samples with submicroscopic malaria infection. Here, the reproducibility of two well-established PCR protocols (nested-PCR and real-time PCR for the Plasmodium 18 small subunit rRNA gene were evaluated in a panel of 34 blood field samples from individuals that are potential reservoirs of malaria infection, but were negative for malaria by optical microscopy. Regardless of the PCR protocol, a large variation between the PCR replicates was observed, leading to alternating positive and negative results in 38% (13 out of 34 of the samples. These findings were quite different from those obtained from the microscopy-positive patients or the unexposed individuals; the diagnosis of these individuals could be confirmed based on the high reproducibility and specificity of the PCR-based protocols. The limitation of PCR amplification was restricted to the field samples with very low levels of parasitaemia because titrations of the DNA templates were able to detect < 3 parasites/µL in the blood. In conclusion, conventional PCR protocols require careful interpretation in cases of submicroscopic malaria infection, as inconsistent and false-negative results can occur.
Energy Technology Data Exchange (ETDEWEB)
Lemal, Philipp; Geers, Christoph; Monnier, Christophe A.; Crippa, Federica; Daum, Leopold; Urban, Dominic A.; Rothen-Rutishauser, Barbara [Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg (Switzerland); Bonmarin, Mathias, E-mail: mathias.bonmarin@zhaw.ch [Institute of Computational Physics, Zurich University of Applied Sciences, Technikumstrasse 9, 8400 Winterthur (Switzerland); Petri-Fink, Alke, E-mail: alke.fink@unifr.ch [Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg (Switzerland); Chemistry Department, University of Fribourg, Chemin du Museé 9, CH-1700 Fribourg (Switzerland); Moore, Thomas L., E-mail: thomaslee.moore@unifr.ch [Adolphe Merkle Institute, University of Fribourg, Chemin des Verdiers 4, CH-1700 Fribourg (Switzerland)
2017-04-01
Lock-in thermography (LIT) is a sensitive imaging technique generally used in engineering and materials science (e.g. detecting defects in composite materials). However, it has recently been expanded for investigating the heating power of nanomaterials, such as superparamagnetic iron oxide nanoparticles (SPIONs). Here we implement LIT as a rapid and reproducible method that can evaluate the heating potential of various sizes of SPIONs under an alternating magnetic field (AMF), as well as the limits of detection for each particle size. SPIONs were synthesized via thermal decomposition and stabilized in water via a ligand transfer process. Thermographic measurements of SPIONs were made by stimulating particles of varying sizes and increasing concentrations under an AMF. Furthermore, a commercially available SPION sample was included as an external reference. While the size dependent heating efficiency of SPIONs has been previously described, our objective was to probe the sensitivity limits of LIT. For certain size regimes it was possible to detect signals at concentrations as low as 0.1 mg Fe/mL. Measuring at different concentrations enabled a linear regression analysis and extrapolation of the limit of detection for different size nanoparticles. - Highlights: • A multi-sample screening assessment of magnetic nanoparticle thermal characteristics is shown via lock-in thermography. • Lower concentration limit of nanoparticle detection based on particle size is proposed. • A commercially available reference sample indicates the stability and reproducibility of LIT.
Zhou, Danfeng; Yu, Peichang; Wang, Lianchun; Li, Jie
2017-11-01
The levitation gap of the urban maglev train is around 8 mm, which puts a rather high requirement on the smoothness of the track. In practice, it is found that the track irregularity may cause stability problems when the maglev train is traveling. In this paper, the dynamic response of the levitation module, which is the basic levitation structure of the urban maglev train, is investigated in the presence of track irregularities. Analyses show that due to the structural configuration of the levitation module, the vibration of the levitation gap may be amplified and "resonances" may be observed under some specified track wavelengths and train speeds; besides, it is found that the gap vibration of the rear levitation unit in a levitation module is more significant than that of the front levitation unit, which agrees well with practice. To suppress the vibration of the rear levitation gap, an adaptive vibration control method is proposed, which utilizes the information of the front levitation unit as a reference. A pair of mirror FIR (finite impulse response) filters are designed and tuned by an adaptive mechanism, and they produce a compensation signal for the rear levitation controller to cancel the disturbance brought by the track irregularity. Simulations under some typical track conditions, including the sinusoidal track profile, random track irregularity, as well as track steps, indicate that the adaptive vibration control scheme can significantly reduce the amplitude of the rear gap vibration, which provides a method to improve the stability and ride comfort of the maglev train.
Canham, Colin D; Schreck, Michael J; Maqsoodi, Noorullah; Doolittle, Madison; Olles, Mark; Elfar, John C
2015-06-01
To develop a nondestructive method of measuring distal radioulnar joint (DRUJ) joint reaction force (JRF) that preserves all periarticular soft tissues and more accurately reflects in vivo conditions. Eight fresh-frozen human cadaveric limbs were obtained. A threaded Steinmann pin was placed in the middle of the lateral side of the distal radius transverse to the DRUJ. A second pin was placed into the middle of the medial side of the distal ulna colinear to the distal radial pin. Specimens were mounted onto a tensile testing machine using a custom fixture. A uniaxial distracting force was applied across the DRUJ while force and displacement were simultaneously measured. Force-displacement curves were generated and a best-fit polynomial was solved to determine JRF. All force-displacement curves demonstrated an initial high slope where relatively large forces were required to distract the joint. This ended with an inflection point followed by a linear area with a low slope, where small increases in force generated larger amounts of distraction. Each sample was measured 3 times and there was high reproducibility between repeated measurements. The average baseline DRUJ JRF was 7.5 N (n = 8). This study describes a reproducible method of measuring DRUJ reaction forces that preserves all periarticular stabilizing structures. This technique of JRF measurement may also be suited for applications in the small joints of the wrist and hand. Changes in JRF can alter native joint mechanics and lead to pathology. Reliable methods of measuring these forces are important for determining how pathology and surgical interventions affect joint biomechanics. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.
Free vibration of finite cylindrical shells by the variational method
International Nuclear Information System (INIS)
Campen, D.H. van; Huetink, J.
1975-01-01
The calculation of the free vibrations of circular cylindrical shells of finite length has been of engineer's interest for a long time. The motive for the present calculations originates from a particular type of construction at the inlet of a sodium heated superheater with helix heating bundle for SNR-Kalkar. The variational analysis is based on a modified energy functional for cylindrical shells, proposed by Koiter and resulting in Morley's equilibrium equations. As usual, the dispacement amplitude is assumed to be distributed harmonically in the circumferential direction of the shell. Following the method of Gontkevich, the dependence between the displacements of the shell middle surface and the axial shell co-ordinate is expressed approximately by a set of eigenfunctions of a free vibrating beam satisfying the desired boundary conditions. Substitution of this displacement expression into the virtual work equation for the complete shell leads to a characteristic equation determining the natural frequencies. The calculations are carried out for a clamped-clamped and a clamped-free cylinder. A comparison is given between the above numerical results and experimental and theoretical results from literature. In addition, the influence of surrounding fluid mass on the above frequencies is analysed for a clamped-clamped shell. The solution for the velocity potential used in this case differs from the solutions used in literature until now in that not only travelling waves in the axial direction are considered. (Auth.)
Principles of Vibrational Spectroscopic Methods and their Application to Bioanalysis
DEFF Research Database (Denmark)
Moore, David S.; Jepsen, Peter Uhd; Volka, Karel
2014-01-01
imaging, fiber optic probes for in vivo and in vitro analysis, and methods to obtain depth profile information. The issue of fluorescence interference will be considered from the perspectives of excitation wavelength selection and data treatment. Methods to optimize signal to noise with minimized...... excitation laser irradiance to avoid sample damage are also discussed. This chapter then reviews applications of Raman spectroscopy to bioanalysis. Areas discussed include pathology, cytopathology, single-cell analysis, in vivo and in vitro tissue characterization, chemical composition of cell components...... as conformation of DNA and proteins), vibrations of inter- and intramolecular hydrogen bonds in solid-state materials, as well as picosecond dynamics in liquid solutions. This chapter reviews modern instrumentation and techniques for THz spectroscopy, with emphasis on applications in bioanalysis....
Combination of dynamic and integral methods for generating reproducible functional CBF images
International Nuclear Information System (INIS)
Lammertsma, A.A.; Cunningham, V.J.; Deiber, M.P.; Heather, J.D.; Bloomfield, P.M.; Nutt, J.; Frackowiak, R.S.; Jones, T.
1990-01-01
A new method to measure regional CBF is presented, applying both dynamic and integral analyses to a dynamic sequence of positron emission tomographic scans collected during and following the administration of H2(15)O (inhalation of C15O2). The dynamic analysis is used to correct continuously monitored arterial whole-blood activity for delay and dispersion relative to tissue scans. An integral analysis including corrections for this delay and dispersion is then used to calculate CBF on a pixel-by-pixel basis. Normal values and reproducibility over a 2-h period are presented, together with the results of validation and simulation studies. The results indicate that the single-tissue compartment model adequately describes the distribution of H2(15)O in the brain, without recourse to postulating a nonexchanging water pool
Watkins, Mike R; Oliver, Richard J
2017-07-01
Objectives The objectives were to examine the density, bubble size distribution and durability of sodium tetradecyl sulphate foam and the consistency of production of foam by a number of different operators using the Tessari method. Methods 1% and 3% sodium tetradecyl sulphate sclerosant foam was produced by an experienced operator and a group of inexperienced operators using either a 1:3 or 1:4 liquid:air ratio and the Tessari method. The foam density, bubble size distribution and foam durability were measured on freshly prepared foam from each operator. Results The foam density measurements were similar for each of the 1:3 preparations and for each of the 1:4 preparations but not affected by the sclerosant concentration. The bubble size for all preparations were very small immediately after preparation but progressively coalesced to become a micro-foam (foams developed liquid more rapidly when made in a 1:3 ratio (37 s) than in a 1:4 ratio (45 s) but all combinations took similar times to reach 0.4 ml liquid formation. For all the experiments, there was no statistical significant difference between operators. Conclusions The Tessari method of foam production for sodium tetradecyl sulphate sclerosant is consistent and reproducible even when made by inexperienced operators. The best quality foam with micro bubbles should be used within the first minute after production.
A new drilling method-Earthworm-like vibration drilling.
Wang, Peng; Ni, Hongjian; Wang, Ruihe
2018-01-01
The load transfer difficulty caused by borehole wall friction severely limits the penetration rate and extended-reach limit of complex structural wells. A new friction reduction technology termed "earthworm-like drilling" is proposed in this paper to improve the load transfer of complex structural wells. A mathematical model based on a "soft-string" model is developed and solved. The results show that earthworm-like drilling is more effective than single-point vibration drilling. The amplitude and frequency of the pulse pressure and the installation position of the shakers have a substantial impact on friction reduction and load transfer. An optimization model based on the projection gradient method is developed and used to optimize the position of three shakers in a horizontal well. The results verify the feasibility and advantages of earthworm-like drilling, and establish a solid theoretical foundation for its application in oil field drilling.
Holewinski, Ronald J; Jin, Zhicheng; Powell, Matthew J; Maust, Matthew D; Van Eyk, Jennifer E
2013-03-01
Analysis of serum and plasma proteomes is a common approach for biomarker discovery, and the removal of high-abundant proteins, such as albumin and immunoglobins, is usually the first step in the analysis. However, albumin binds peptides and proteins, which raises concerns as to how the removal of albumin could impact the outcome of the biomarker study while ignoring the possibility that this could be a biomarker subproteome itself. The first goal of this study was to test a new commercially available affinity capture reagent from Protea Biosciences and to compare the efficiency and reproducibility to four other commercially available albumin depletion methods. The second goal of this study was to determine if there is a highly efficient albumin depletion/isolation system that minimizes sample handling and would be suitable for large numbers of samples. Two of the methods tested (Sigma and ProteaPrep) showed an albumin depletion efficiency of 97% or greater for both serum and cerebrospinal fluid (CSF). Isolated serum and CSF albuminomes from ProteaPrep spin columns were analyzed directly by LC-MS/MS, identifying 128 serum (45 not previously reported) and 94 CSF albuminome proteins (17 unique to the CSF albuminome). Serum albuminome was also isolated using Vivapure anti-HSA columns for comparison, identifying 105 proteins, 81 of which overlapped with the ProteaPrep method. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
An improved cost-effective, reproducible method for evaluation of bone loss in a rodent model.
Fine, Daniel H; Schreiner, Helen; Nasri-Heir, Cibele; Greenberg, Barbara; Jiang, Shuying; Markowitz, Kenneth; Furgang, David
2009-02-01
This study was designed to investigate the utility of two "new" definitions for assessment of bone loss in a rodent model of periodontitis. Eighteen rats were divided into three groups. Group 1 was infected by Aggregatibacter actinomycetemcomitans (Aa), group 2 was infected with an Aa leukotoxin knock-out, and group 3 received no Aa (controls). Microbial sampling and antibody titres were determined. Initially, two examiners measured the distance from the cemento-enamel-junction to alveolar bone crest using the three following methods; (1) total area of bone loss by radiograph, (2) linear bone loss by radiograph, (3) a direct visual measurement (DVM) of horizontal bone loss. Two "new" definitions were adopted; (1) any site in infected animals showing bone loss >2 standard deviations above the mean seen at that site in control animals was recorded as bone loss, (2) any animal with two or more sites in any quadrant affected by bone loss was considered as diseased. Using the "new" definitions both evaluators independently found that infected animals had significantly more disease than controls (DVM system; p<0.05). The DVM method provides a simple, cost effective, and reproducible method for studying periodontal disease in rodents.
DEFF Research Database (Denmark)
Jensen, Peter S; Ziebell, Morten; Skouboe, Glenna
2011-01-01
In nuclear medicine brain imaging, it is important to delineate regions of interest (ROIs) so that the outcome is both accurate and reproducible. The purpose of this study was to validate a new time-saving algorithm (DATquan) for accurate and reproducible quantification of the striatal dopamine t...... transporter (DAT) with appropriate radioligands and SPECT and without the need for structural brain scanning....
Research on vibration signal analysis and extraction method of gear local fault
Yang, X. F.; Wang, D.; Ma, J. F.; Shao, W.
2018-02-01
Gear is the main connection parts and power transmission parts in the mechanical equipment. If the fault occurs, it directly affects the running state of the whole machine and even endangers the personal safety. So it has important theoretical significance and practical value to study on the extraction of the gear fault signal and fault diagnosis of the gear. In this paper, the gear local fault as the research object, set up the vibration model of gear fault vibration mechanism, derive the vibration mechanism of the gear local fault and analyzes the similarities and differences of the vibration signal between the gear non fault and the gears local faults. In the MATLAB environment, the wavelet transform algorithm is used to denoise the fault signal. Hilbert transform is used to demodulate the fault vibration signal. The results show that the method can denoise the strong noise mechanical vibration signal and extract the local fault feature information from the fault vibration signal..
Non-traditional vibration mitigation methods for reciprocating compressor system
Eijk, A.; Lange, T.J. de; Vreugd, J. de; Slis, E.J.P.
2016-01-01
Reciprocating compressors generate vibrations caused by pulsation-induced forces, mechanical (unbalanced) free forces and moments, crosshead guide forces and cylinder stretch forces. The traditional way of mitigating the vibration and cyclic stress levels to avoid fatigue failure of parts of the
A simple, reproducible and sensitive spectrophotometric method to estimate microalgal lipids
Energy Technology Data Exchange (ETDEWEB)
Chen Yimin [ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom); Vaidyanathan, Seetharaman, E-mail: s.vaidyanathan@sheffield.ac.uk [ChELSI Institute, Department of Chemical and Biological Engineering, University of Sheffield, Sheffield S1 3JD (United Kingdom)
2012-04-29
Highlights: Black-Right-Pointing-Pointer FAs released from lipids form complex with Cu-TEA in chloroform. Black-Right-Pointing-Pointer The FA-Cu-TEA complex gives strong absorbance at 260 nm. Black-Right-Pointing-Pointer The absorbance is sensitive and independent of C-atom number in the FAs (10-18). Black-Right-Pointing-Pointer Microalgal lipid extract and pure FA (such as C16) can both be used as standards. - Abstract: Quantification of total lipids is a necessity for any study of lipid production by microalgae, especially given the current interest in microalgal carbon capture and biofuels. In this study, we employed a simple yet sensitive method to indirectly measure the lipids in microalgae by measuring the fatty acids (FA) after saponification. The fatty acids were reacted with triethanolamine-copper salts (TEA-Cu) and the ternary TEA-Cu-FA complex was detected at 260 nm using a UV-visible spectrometer without any colour developer. The results showed that this method could be used to analyse low levels of lipids in the range of nano-moles from as little as 1 mL of microalgal culture. Furthermore, the structure of the TEA-Cu-FA complex and related reaction process are proposed to better understand this assay. There is no special instrument required and the method is very reproducible. To the best of our knowledge, this is the first report of the use of UV absorbance of copper salts with FA as a method to estimate lipids in algal cultures. It will pave the way for a more convenient assay of lipids in microalgae and can readily be expanded for estimating lipids in other biological systems.
A simple, reproducible and sensitive spectrophotometric method to estimate microalgal lipids
International Nuclear Information System (INIS)
Chen Yimin; Vaidyanathan, Seetharaman
2012-01-01
Highlights: ► FAs released from lipids form complex with Cu–TEA in chloroform. ► The FA–Cu–TEA complex gives strong absorbance at 260 nm. ► The absorbance is sensitive and independent of C-atom number in the FAs (10–18). ► Microalgal lipid extract and pure FA (such as C16) can both be used as standards. - Abstract: Quantification of total lipids is a necessity for any study of lipid production by microalgae, especially given the current interest in microalgal carbon capture and biofuels. In this study, we employed a simple yet sensitive method to indirectly measure the lipids in microalgae by measuring the fatty acids (FA) after saponification. The fatty acids were reacted with triethanolamine–copper salts (TEA–Cu) and the ternary TEA–Cu–FA complex was detected at 260 nm using a UV–visible spectrometer without any colour developer. The results showed that this method could be used to analyse low levels of lipids in the range of nano-moles from as little as 1 mL of microalgal culture. Furthermore, the structure of the TEA–Cu–FA complex and related reaction process are proposed to better understand this assay. There is no special instrument required and the method is very reproducible. To the best of our knowledge, this is the first report of the use of UV absorbance of copper salts with FA as a method to estimate lipids in algal cultures. It will pave the way for a more convenient assay of lipids in microalgae and can readily be expanded for estimating lipids in other biological systems.
International Nuclear Information System (INIS)
Tomilov, B.V.
1979-01-01
The transducer is pressed to the specimen, a lubricating coating being applied as an intermediate layer. By means of a vibrator belonging to the transducer there are generated vibrations, the growth rate of the amplitude of the reflected signal picked up being observed. This growth rate is monotonously decreasing. If the growth rate is abruptly decreasing or if the amplitude of the measured signal remains constant the vibrator is turned off, because now good acoustic contact is established. After a short time of waiting for the residual stress of the transducer to decay, recording of the ultrasonic parameters may then be taken up. The method can be applied to thickness measurements and inhomogeneous materials with low surface quality. (RW) [de
A method for regulating strong nonlinear vibration energy of the flexible arm
Directory of Open Access Journals (Sweden)
Yushu Bian
2015-07-01
Full Text Available For an oscillating system, large amplitude indicates strong vibration energy. In this article, modal interaction is used as a useful means to regulate strong nonlinear vibration energy of the flexible arm undergoing rigid motion. A method is put forward to migrate and dissipate vibration energy based on modal interaction. By means of multiple-scale perturbation analysis, it is proven that internal resonance can be successfully established between modes of the flexible arm and the vibration absorber. Through examples and analyses, it is verified that this control method is effective in regulating strong vibration energy and can be used to suppress strong nonlinear vibration of the flexible arm undergoing rigid motion.
Signal Processing Methods for Removing the Effects of Whole Body Vibration upon Speech
Bitner, Rachel M.; Begault, Durand R.
2014-01-01
Humans may be exposed to whole-body vibration in environments where clear speech communications are crucial, particularly during the launch phases of space flight and in high-performance aircraft. Prior research has shown that high levels of vibration cause a decrease in speech intelligibility. However, the effects of whole-body vibration upon speech are not well understood, and no attempt has been made to restore speech distorted by whole-body vibration. In this paper, a model for speech under whole-body vibration is proposed and a method to remove its effect is described. The method described reduces the perceptual effects of vibration, yields higher ASR accuracy scores, and may significantly improve intelligibility. Possible applications include incorporation within communication systems to improve radio-communication systems in environments such a spaceflight, aviation, or off-road vehicle operations.
The impact of accelerometer mounting methods on the level of vibrations recorded at ground surface
Directory of Open Access Journals (Sweden)
Krzysztof Czech
2014-08-01
Full Text Available The paper presents the results of field research based on the measurements of accelerations recorded at ground surface. The source of the vibration characterized by high repetition rate of pulse parameters was light falling weight deflectometer ZFG-01. Measurements of vibrations have been carried out using top quality high-precision measuring system produced by Brüel&Kiær. Accelerometers were mounted on a sandy soil surface at the measuring points located radially at 5-m and 10-m distances from the source of vibration. The paper analyses the impact that the method of mounting accelerometers on the ground has on the level of the recorded values of accelerations of vibrations. It has been shown that the method of attaching the sensor to the surface of the ground is crucial for the credibility of the performed measurements.[b]Keywords[/b]: geotechnics, surface vibrations, ground, vibration measurement
Brzica, Hrvoje; Abdullahi, Wazir; Reilly, Bianca G; Ronaldson, Patrick T
2018-05-07
The blood-brain barrier (BBB) is a dynamic barrier tissue that responds to various pathophysiological and pharmacological stimuli. Such changes resulting from these stimuli can greatly modulate drug delivery to the brain and, by extension, cause considerable challenges in the treatment of central nervous system (CNS) diseases. Many BBB changes that affect pharmacotherapy, involve proteins that are localized and expressed at the level of endothelial cells. Indeed, such knowledge on BBB physiology in health and disease has sparked considerable interest in the study of these membrane proteins. From a basic science research standpoint, this implies a requirement for a simple but robust and reproducible method for isolation of microvessels from brain tissue harvested from experimental animals. In order to prepare membrane samples from freshly isolated microvessels, it is essential that sample preparations be enriched in endothelial cells but limited in the presence of other cell types of the neurovascular unit (i.e., astrocytes, microglia, neurons, pericytes). An added benefit is the ability to prepare samples from individual animals in order to capture the true variability of protein expression in an experimental population. In this manuscript, details regarding a method that is utilized for isolation of rat brain microvessels and preparation of membrane samples are provided. Microvessel enrichment, from samples derived, is achieved by using four centrifugation steps where dextran is included in the sample buffer. This protocol can easily be adapted by other laboratories for their own specific applications. Samples generated from this protocol have been shown to yield robust experimental data from protein analysis experiments that can greatly aid the understanding of BBB responses to physiological, pathophysiological, and pharmacological stimuli.
Fuel Rod Vibration Measurement Method using a Flap and its Verification
Energy Technology Data Exchange (ETDEWEB)
Yoo, Joo Young; Park, Nam Gyu; Suh, Jung Min; Jeon, Kyeong Lak [KEPCO NF Co., Daejeon (Korea, Republic of)
2011-10-15
Flow-induced vibration is a critical factor for the mechanical integrity of a fuel rod. This vibration can cause leaked fuel through the mechanism, such as grid to rod fretting. To minimize the failures caused by flow-induced vibration, a robust design is needed which takes into account vibrational characteristics. That is, the spacer grid design should be developed to avoid any excessive vibration. On the one hand, if fuel rod vibration can be measured, an estimation of the excitation forces, which are a critical cause of rod failure, should be possible. Therefore, by applying an external force, flow-induced vibration can be roughly estimated when the fuel rod vibration model is used. KEPCO Nuclear Fuel developed the test loop to research flow-induced vibration as shown in Fig.1. The investigation flow-induced vibration (INFINIT) - the test facility - can measure the grid strap vibration and pressure drop of a 5x5 small scale fuel bundle. Basically, using a Laser Doppler Vibrometer (LDV), the vibration of a structure immersed in high speed fluid can be measured. Grid strap vibration is easily measured using an LDV. However, it is quite difficult to measure fuel rod vibration because of the round surface shape of the rods. In addition, measuring current method using the LDV, it was only possible to directly measure fuel rod vibration at the first row of the bundle as the rods behind the first row are obscured. To solve this problem, a thin flap, as shown in Fig. 2(a) can be used as a reflecting target, gaining access to rods within the bundle. The flap is attached to the fuel rod, as in Fig. 2(b). As a result, most of the inner rod vibration can be measured. Before using a flap to measure fuel rod vibration, a verification process was needed to show whether the LDV signal from the flap vibration provided equivalent and reliable signals. Therefore, impact testing was carried out on the fuel rod using a flap. The LDV signals were then compared with accelerometer
International Nuclear Information System (INIS)
Tsuji, Takashi; Maekawa, Akira; Takahashi, Tsuneo
2013-01-01
In nuclear power plants, vibrational stress of piping is measured to prevent its fatigue failures. Easier handling and more efficient performance is desirable for the measurement of vibrational stress. The authors have proposed a method to measure vibrational stress using optical contactless displacement sensors, and have developed a device based on the method. In addition, they downsized the device and improved the method to allow its use for measurements even in narrow spaces in the plants. In this study, vibrational experiment using branch pipes and the device was conducted to confirm the measurement accuracy of the improved method. It was found that the improved method have sufficient accuracy for screening to evaluate the vibrational stress. It was also found that this measurement method was thought to be susceptible to the vibration of main pipe. So a technique was proposed to improve the accuracy of the measurement in this paper. (author)
Prest, Emmanuelle I E C; Hammes, Frederik A.; Kö tzsch, Stefan; van Loosdrecht, Mark C.M.; Vrouwenvelder, Johannes S.
2013-01-01
Flow cytometry (FCM) is a rapid, cultivation-independent tool to assess and evaluate bacteriological quality and biological stability of water. Here we demonstrate that a stringent, reproducible staining protocol combined with fixed FCM operational and gating settings is essential for reliable quantification of bacteria and detection of changes in aquatic bacterial communities. Triplicate measurements of diverse water samples with this protocol typically showed relative standard deviation values and 95% confidence interval values below 2.5% on all the main FCM parameters. We propose a straightforward and instrument-independent method for the characterization of water samples based on the combination of bacterial cell concentration and fluorescence distribution. Analysis of the fluorescence distribution (or so-called fluorescence fingerprint) was accomplished firstly through a direct comparison of the raw FCM data and subsequently simplified by quantifying the percentage of large and brightly fluorescent high nucleic acid (HNA) content bacteria in each sample. Our approach enables fast differentiation of dissimilar bacterial communities (less than 15min from sampling to final result), and allows accurate detection of even small changes in aquatic environments (detection above 3% change). Demonstrative studies on (a) indigenous bacterial growth in water, (b) contamination of drinking water with wastewater, (c) household drinking water stagnation and (d) mixing of two drinking water types, univocally showed that this FCM approach enables detection and quantification of relevant bacterial water quality changes with high sensitivity. This approach has the potential to be used as a new tool for application in the drinking water field, e.g. for rapid screening of the microbial water quality and stability during water treatment and distribution in networks and premise plumbing. © 2013 Elsevier Ltd.
Prest, Emmanuelle I E C
2013-12-01
Flow cytometry (FCM) is a rapid, cultivation-independent tool to assess and evaluate bacteriological quality and biological stability of water. Here we demonstrate that a stringent, reproducible staining protocol combined with fixed FCM operational and gating settings is essential for reliable quantification of bacteria and detection of changes in aquatic bacterial communities. Triplicate measurements of diverse water samples with this protocol typically showed relative standard deviation values and 95% confidence interval values below 2.5% on all the main FCM parameters. We propose a straightforward and instrument-independent method for the characterization of water samples based on the combination of bacterial cell concentration and fluorescence distribution. Analysis of the fluorescence distribution (or so-called fluorescence fingerprint) was accomplished firstly through a direct comparison of the raw FCM data and subsequently simplified by quantifying the percentage of large and brightly fluorescent high nucleic acid (HNA) content bacteria in each sample. Our approach enables fast differentiation of dissimilar bacterial communities (less than 15min from sampling to final result), and allows accurate detection of even small changes in aquatic environments (detection above 3% change). Demonstrative studies on (a) indigenous bacterial growth in water, (b) contamination of drinking water with wastewater, (c) household drinking water stagnation and (d) mixing of two drinking water types, univocally showed that this FCM approach enables detection and quantification of relevant bacterial water quality changes with high sensitivity. This approach has the potential to be used as a new tool for application in the drinking water field, e.g. for rapid screening of the microbial water quality and stability during water treatment and distribution in networks and premise plumbing. © 2013 Elsevier Ltd.
Directory of Open Access Journals (Sweden)
Cheng-Wei Fei
2014-01-01
Full Text Available To improve the diagnosis capacity of rotor vibration fault in stochastic process, an effective fault diagnosis method (named Process Power Spectrum Entropy (PPSE and Support Vector Machine (SVM (PPSE-SVM, for short method was proposed. The fault diagnosis model of PPSE-SVM was established by fusing PPSE method and SVM theory. Based on the simulation experiment of rotor vibration fault, process data for four typical vibration faults (rotor imbalance, shaft misalignment, rotor-stator rubbing, and pedestal looseness were collected under multipoint (multiple channels and multispeed. By using PPSE method, the PPSE values of these data were extracted as fault feature vectors to establish the SVM model of rotor vibration fault diagnosis. From rotor vibration fault diagnosis, the results demonstrate that the proposed method possesses high precision, good learning ability, good generalization ability, and strong fault-tolerant ability (robustness in four aspects of distinguishing fault types, fault severity, fault location, and noise immunity of rotor stochastic vibration. This paper presents a novel method (PPSE-SVM for rotor vibration fault diagnosis and real-time vibration monitoring. The presented effort is promising to improve the fault diagnosis precision of rotating machinery like gas turbine.
Recursive-operator method in vibration problems for rod systems
Rozhkova, E. V.
2009-12-01
Using linear differential equations with constant coefficients describing one-dimensional dynamical processes as an example, we show that the solutions of these equations and systems are related to the solution of the corresponding numerical recursion relations and one does not have to compute the roots of the corresponding characteristic equations. The arbitrary functions occurring in the general solution of the homogeneous equations are determined by the initial and boundary conditions or are chosen from various classes of analytic functions. The solutions of the inhomogeneous equations are constructed in the form of integro-differential series acting on the right-hand side of the equation, and the coefficients of the series are determined from the same recursion relations. The convergence of formal solutions as series of a more general recursive-operator construction was proved in [1]. In the special case where the solutions of the equation can be represented in separated variables, the power series can be effectively summed, i.e., expressed in terms of elementary functions, and coincide with the known solutions. In this case, to determine the natural vibration frequencies, one obtains algebraic rather than transcendental equations, which permits exactly determining the imaginary and complex roots of these equations without using the graphic method [2, pp. 448-449]. The correctness of the obtained formulas (differentiation formulas, explicit expressions for the series coefficients, etc.) can be verified directly by appropriate substitutions; therefore, we do not prove them here.
Gennaro, G; Ballaminut, A; Contento, G
2017-09-01
This study aims to illustrate a multiparametric automatic method for monitoring long-term reproducibility of digital mammography systems, and its application on a large scale. Twenty-five digital mammography systems employed within a regional screening programme were controlled weekly using the same type of phantom, whose images were analysed by an automatic software tool. To assess system reproducibility levels, 15 image quality indices (IQIs) were extracted and compared with the corresponding indices previously determined by a baseline procedure. The coefficients of variation (COVs) of the IQIs were used to assess the overall variability. A total of 2553 phantom images were collected from the 25 digital mammography systems from March 2013 to December 2014. Most of the systems showed excellent image quality reproducibility over the surveillance interval, with mean variability below 5%. Variability of each IQI was 5%, with the exception of one index associated with the smallest phantom objects (0.25 mm), which was below 10%. The method applied for reproducibility tests-multi-detail phantoms, cloud automatic software tool to measure multiple image quality indices and statistical process control-was proven to be effective and applicable on a large scale and to any type of digital mammography system. • Reproducibility of mammography image quality should be monitored by appropriate quality controls. • Use of automatic software tools allows image quality evaluation by multiple indices. • System reproducibility can be assessed comparing current index value with baseline data. • Overall system reproducibility of modern digital mammography systems is excellent. • The method proposed and applied is cost-effective and easily scalable.
Reduction method for residual stress of welded joint using random vibration
International Nuclear Information System (INIS)
Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro
2005-01-01
Welded joints are used for construction of many structures. Residual stress is induced near the bead caused by locally given heat. Tensile residual stress on the surface may reduce fatigue strength. In this paper, a new method for reduction of residual stress using vibration during welding is proposed. As vibrational load, random vibration, white noise and filtered white noise are used. Two thin plates are butt-welded. Residual stress is measured with a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. It is concluded that tensile residual stress near the bead is reduced by using random vibration during welding
An efficient and reproducible method for measuring hydrogen peroxide in exhaled breath condensate.
Beurden, W.J.C van; Harff, G.A.; Dekhuijzen, P.N.R.; Bosch, M.J. van den; Creemers, J.P.H.M.; Smeenk, F.J.M.W.
2002-01-01
We investigated the sensitivity and reproducibility of a test procedure for measuring hydrogen peroxide (H202) in exhaled breath condensate and the effect of storage of the condensate on the H2O2 concentration, and compared the results to previous studies.Twenty stable COPD patients breathed into
International Nuclear Information System (INIS)
Saito, A; Kuroishi, M; Nakai, H
2016-01-01
This paper concerns the noise and structural vibration caused by rotating electric machines. Special attention is given to the magnetic-force induced vibration response of interior-permanent magnet machines. In general, to accurately predict and control the vibration response caused by the electric machines, it is inevitable to model not only the magnetic force induced by the fluctuation of magnetic fields, but also the structural dynamic characteristics of the electric machines and surrounding structural components. However, due to complicated boundary conditions and material properties of the components, such as laminated magnetic cores and varnished windings, it has been a challenge to compute accurate vibration response caused by the electric machines even after their physical models are available. In this paper, we propose a highly-accurate vibration prediction method that couples experimentally-obtained discrete structural transfer functions and numerically-obtained distributed magnetic-forces. The proposed vibration synthesis methodology has been applied to predict vibration responses of an interior permanent magnet machine. The results show that the predicted vibration response of the electric machine agrees very well with the measured vibration response for several load conditions, for wide frequency ranges. (paper)
System and method for damping vibration in a drill string
Wassell, Mark Ellsworth; Turner, William Evans; Burgess, Daniel E; Perry, Carl Allison
2014-03-04
A system for damping vibration in a drill string can include a valve assembly having a supply of a fluid, a first member, and a second member capable of moving in relation to first member in response to vibration of the drill bit. The first and second members define a first and a second chamber for holding the fluid. Fluid can flow between the first and second chambers in response to the movement of the second member in relation to the first member. The valve assembly can also include a coil or a valve for varying a resistance of the fluid to flow between the first and second chambers.
DEFF Research Database (Denmark)
Plum, Jakob; Madsen, Cecilie M; Teleki, Alexandra
2017-01-01
order for the three model compounds using the SSPM (aprepitant > felodipine ≈ fenofibrate). The α-value is dependent on the experimental setup and can be used as a parameter to evaluate the uniformity of the data set. This study indicated that the SSPM was able to obtain the same rank order of the β...... compound available for absorption. However, due to the stochastic nature of nucleation, supersaturating drug delivery systems may lead to inter- and intrapersonal variability. The ability to define a feasible range with respect to the supersaturation level is a crucial factor for a successful formulation...... reproducibility study of felodipine was conducted, after which seven partners contributed with data for three model compounds; aprepitant, felodipine, and fenofibrate, to determine the interlaboratory reproducibility of the SSPM. The first part of the SSPM determines the apparent degrees of supersaturation (a...
Directory of Open Access Journals (Sweden)
Mohammad Rastgaar
2009-01-01
Full Text Available This paper provides a state-of-the-art review of eigenstructure assignment methods for vibration cancellation. Eigenstructure assignment techniques have been widely used during the past three decades for vibration suppression in structures, especially in large space structures. These methods work similar to mode localization in which global vibrations are managed such that they remain localized within the structure. Such localization would help reducing vibrations more effectively than other methods of vibration cancellation, by virtue of confining the vibrations close to the source of disturbance. The common objective of different methods of eigenstructure assignment is to provide controller design freedom beyond pole placement, and define appropriate shapes for the eigenvectors of the systems. These methods; however, offer a large and complex design space of options that can often overwhelm the control designer. Recent developments in orthogonal eigenstructure control offers a significant simplification of the design task while allowing some experience-based design freedom. The majority of the papers from the past three decades in structural vibration cancellation using eigenstructure assignment methods are reviewed, along with recent studies that introduce new developments in eigenstructure assignment techniques.
Energy Technology Data Exchange (ETDEWEB)
Lee, Hyun; Kim, Yeon Whan [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center; Kim, Tae Ryong; Park, Jin Ho [Korea Atomic Energy Research Inst., Daeduk (Korea, Republic of)
1996-08-01
The main steam piping of nuclear power plant which runs between steam generator and high pressure turbine has been experienced to have a severe effect on the safe operation of the plant due to the vibration induced by the steam flowing inside the piping. The imposed cyclic loads by the vibration could result in the degradation of the related structures such as connection parts between main instruments, valves, pipe supports and building. The objective of the study is to reduce the vibration level of Wolsung nuclear power plant unit 1 main steam pipeline by analyzing vibration characteristics of the piping, identifying sources of the vibration and developing a vibration reduction method .The location of the maximum vibration is piping between the main steam header and steam chest .The stress level was found to be within the allowable limit .The main vibration frequency was found to be 4{approx}6 Hz which is the same as the natural frequency from model test .A vibration reduction method using pipe supports of energy absorbing type(WEAR)is selected .The measured vibration level after WEAR installation was reduced about 36{approx}77% in displacement unit (author). 36 refs., 188 figs.
Numerical analysis using state space method for vibration control of ...
African Journals Online (AJOL)
ATHARVA
carried out for two cases namely car moving on sagged bridges and car ... the vibrations of steel moment resisting frame in reinforced cement concrete buildings. ... active or semi-active dampers rolled into one (Spencer Jr. and Soong, 1999). ... implementation cost, low power consumption, ease of control, simple design ...
An adjoint method of sensitivity analysis for residual vibrations of structures subject to impacts
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.
Cheng, Cynthia; Lee, Chadd W; Daskalakis, Constantine
2015-10-27
Capillaroscopy is a non-invasive, efficient, relatively inexpensive and easy to learn methodology for directly visualizing the microcirculation. The capillaroscopy technique can provide insight into a patient's microvascular health, leading to a variety of potentially valuable dermatologic, ophthalmologic, rheumatologic and cardiovascular clinical applications. In addition, tumor growth may be dependent on angiogenesis, which can be quantitated by measuring microvessel density within the tumor. However, there is currently little to no standardization of techniques, and only one publication to date reports the reliability of a currently available, complex computer based algorithms for quantitating capillaroscopy data.(1) This paper describes a new, simpler, reliable, standardized capillary counting algorithm for quantitating nailfold capillaroscopy data. A simple, reproducible computerized capillaroscopy algorithm such as this would facilitate more widespread use of the technique among researchers and clinicians. Many researchers currently analyze capillaroscopy images by hand, promoting user fatigue and subjectivity of the results. This paper describes a novel, easy-to-use automated image processing algorithm in addition to a reproducible, semi-automated counting algorithm. This algorithm enables analysis of images in minutes while reducing subjectivity; only a minimal amount of training time (in our experience, less than 1 hr) is needed to learn the technique.
Conville, Patricia S; Brown-Elliott, Barbara A; Wallace, Richard J; Witebsky, Frank G; Koziol, Deloris; Hall, Geraldine S; Killian, Scott B; Knapp, Cindy C; Warshauer, David; Van, Tam; Wengenack, Nancy L; Deml, Sharon; Woods, Gail L
2012-04-01
Antimicrobial susceptibility testing (AST) of clinical isolates of Nocardia is recommended to detect resistance to commonly used antimicrobial agents; such testing is complicated by difficulties in inoculum preparation and test interpretation. In this study, six laboratories performed repetitive broth microdilution testing on single strains of Nocardia brasiliensis, Nocardia cyriacigeorgica, Nocardia farcinica, Nocardia nova, and Nocardia wallacei. For each isolate, a total of 30 microdilution panels from three different lots were tested at most sites. The goal of the study was to determine the inter- and intralaboratory reproducibility of susceptibility testing of this group of isolates. Acceptable agreement (>90% agreement at ±1 dilution of the MIC mode) was found for amikacin, ciprofloxacin, clarithromycin, and moxifloxacin. After eliminating MIC values from single laboratories whose results showed the greatest deviation from those of the remaining laboratories, acceptable agreement was also found for amoxicillin-clavulanic acid, linezolid, minocycline, and tobramycin. Results showed unsatisfactory reproducibility of broth microdilution testing of ceftriaxone with N. cyriacigeorgica and N. wallacei, tigecycline with N. brasiliensis and N. cyriacigeorgica, and sulfonamides with N. farcinica and N. wallacei. N. nova ATCC BAA-2227 is proposed as a quality control organism for AST of Nocardia sp., and the use of a disk diffusion test for sulfisoxazole is proposed as a check of the adequacy of the inoculum and to confirm sulfonamide MIC results.
WAVELETS AND PRINCIPAL COMPONENT ANALYSIS METHOD FOR VIBRATION MONITORING OF ROTATING MACHINERY
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...
Diagnosis of Centrifugal Pump Faults Using Vibration Methods
International Nuclear Information System (INIS)
Albraik, A; Althobiani, F; Gu, F; Ball, A
2012-01-01
Pumps are the largest single consumer of power in industry. This means that faulty pumps cause a high rate of energy loss with associated performance degradation, high vibration levels and significant noise radiation. This paper investigates the correlations between pump performance parameters including head, flow rate and energy consumption and surface vibration for the purpose of both pump condition monitoring and performance assessment. Using an in-house pump system, a number of experiments have been carried out on a centrifugal pump system using five impellers: one in good condition and four others with different defects, and at different flow rates for the comparison purposes. The results have shown that each defective impeller performance curve (showing flow, head, efficiency and NPSH (Net Positive Suction Head) is different from the benchmark curve showing the performance of the impeller in good condition. The exterior vibration responses were investigated to extract several key features to represent the healthy pump condition, pump operating condition and pump energy consumption. In combination, these parameter allow an optimal decision for pump overhaul to be made.
Diagnosis of Centrifugal Pump Faults Using Vibration Methods
Albraik, A.; Althobiani, F.; Gu, F.; Ball, A.
2012-05-01
Pumps are the largest single consumer of power in industry. This means that faulty pumps cause a high rate of energy loss with associated performance degradation, high vibration levels and significant noise radiation. This paper investigates the correlations between pump performance parameters including head, flow rate and energy consumption and surface vibration for the purpose of both pump condition monitoring and performance assessment. Using an in-house pump system, a number of experiments have been carried out on a centrifugal pump system using five impellers: one in good condition and four others with different defects, and at different flow rates for the comparison purposes. The results have shown that each defective impeller performance curve (showing flow, head, efficiency and NPSH (Net Positive Suction Head) is different from the benchmark curve showing the performance of the impeller in good condition. The exterior vibration responses were investigated to extract several key features to represent the healthy pump condition, pump operating condition and pump energy consumption. In combination, these parameter allow an optimal decision for pump overhaul to be made [1].
An analytical method for free vibration analysis of functionally graded beams with edge cracks
Wei, Dong; Liu, Yinghua; Xiang, Zhihai
2012-03-01
In this paper, an analytical method is proposed for solving the free vibration of cracked functionally graded material (FGM) beams with axial loading, rotary inertia and shear deformation. The governing differential equations of motion for an FGM beam are established and the corresponding solutions are found first. The discontinuity of rotation caused by the cracks is simulated by means of the rotational spring model. Based on the transfer matrix method, then the recurrence formula is developed to get the eigenvalue equations of free vibration of FGM beams. The main advantage of the proposed method is that the eigenvalue equation for vibrating beams with an arbitrary number of cracks can be conveniently determined from a third-order determinant. Due to the decrease in the determinant order as compared with previous methods, the developed method is simpler and more convenient to analytically solve the free vibration problem of cracked FGM beams. Moreover, free vibration analyses of the Euler-Bernoulli and Timoshenko beams with any number of cracks can be conducted using the unified procedure based on the developed method. These advantages of the proposed procedure would be more remarkable as the increase of the number of cracks. A comprehensive analysis is conducted to investigate the influences of the location and total number of cracks, material properties, axial load, inertia and end supports on the natural frequencies and vibration mode shapes of FGM beams. The present work may be useful for the design and control of damaged structures.
An Efficient Method of Vibration Diagnostics For Rotating Machinery Using a Decision Tree
Directory of Open Access Journals (Sweden)
Bo Suk Yang
2000-01-01
Full Text Available This paper describes an efficient method to automatize vibration diagnosis for rotating machinery using a decision tree, which is applicable to vibration diagnosis expert system. Decision tree is a widely known formalism for expressing classification knowledge and has been used successfully in many diverse areas such as character recognition, medical diagnosis, and expert systems, etc. In order to build a decision tree for vibration diagnosis, we have to define classes and attributes. A set of cases based on past experiences is also needed. This training set is inducted using a result-cause matrix newly developed in the present work instead of using a conventionally implemented cause-result matrix. This method was applied to diagnostics for various cases taken from published work. It is found that the present method predicts causes of the abnormal vibration for test cases with high reliability.
A new online secondary path modeling method for adaptive active structure vibration control
International Nuclear Information System (INIS)
Pu, Yuxue; Zhang, Fang; Jiang, Jinhui
2014-01-01
This paper proposes a new variable step size FXLMS algorithm with an auxiliary noise power scheduling strategy for online secondary path modeling. The step size for the secondary path modeling filter and the gain of auxiliary noise are varied in accordance with the parameters available directly. The proposed method has a low computational complexity. Computer simulations show that an active vibration control system with the proposed method gives much better vibration attenuation and modeling accuracy at a faster convergence rate than existing methods. National Instruments’ CompactRIO is used as an embedded processor to control simply supported beam vibration. Experimental results indicate that the vibration of the beam has been effectively attenuated. (papers)
Li, Robin; Lin, Xiao; Geng, Haijiang; Li, Zhihui; Li, Jiabing; Lu, Tao; Yan, Fangrong
2015-12-29
Personalized cancer treatments depend on the determination of a patient's genetic status according to known genetic profiles for which targeted treatments exist. Such genetic profiles must be scientifically validated before they is applied to general patient population. Reproducibility of findings that support such genetic profiles is a fundamental challenge in validation studies. The percentage of overlapping genes (POG) criterion and derivative methods produce unstable and misleading results. Furthermore, in a complex disease, comparisons between different tumor subtypes can produce high POG scores that do not capture the consistencies in the functions. We focused on the quality rather than the quantity of the overlapping genes. We defined the rank value of each gene according to importance or quality by PageRank on basis of a particular topological structure. Then, we used the p-value of the rank-sum of the overlapping genes (PRSOG) to evaluate the quality of reproducibility. Though the POG scores were low in different studies of the same disease, the PRSOG was statistically significant, which suggests that sets of differentially expressed genes might be highly reproducible. Evaluations of eight datasets from breast cancer, lung cancer and four other disorders indicate that quality-based PRSOG method performs better than a quantity-based method. Our analysis of the components of the sets of overlapping genes supports the utility of the PRSOG method.
International Nuclear Information System (INIS)
Zheng Bin; Gur, David; Good, Walter F.; Hardesty, Lara A.
2004-01-01
The purpose of this study is to develop a new method for assessment of the reproducibility of computer-aided detection (CAD) schemes for digitized mammograms and to evaluate the possibility of using the implemented approach for improving CAD performance. Two thousand digitized mammograms (representing 500 cases) with 300 depicted verified masses were selected in the study. Series of images were generated for each digitized image by resampling after a series of slight image rotations. A CAD scheme developed in our laboratory was applied to all images to detect suspicious mass regions. We evaluated the reproducibility of the scheme using the detection sensitivity and false-positive rates for the original and resampled images. We also explored the possibility of improving CAD performance using three methods of combining results from the original and resampled images, including simple grouping, averaging output scores, and averaging output scores after grouping. The CAD scheme generated a detection score (from 0 to 1) for each identified suspicious region. A region with a detection score >0.5 was considered as positive. The CAD scheme detected 238 masses (79.3% case-based sensitivity) and identified 1093 false-positive regions (average 0.55 per image) in the original image dataset. In eleven repeated tests using original and ten sets of rotated and resampled images, the scheme detected a maximum of 271 masses and identified as many as 2359 false-positive regions. Two hundred and eighteen masses (80.4%) and 618 false-positive regions (26.2%) were detected in all 11 sets of images. Combining detection results improved reproducibility and the overall CAD performance. In the range of an average false-positive detection rate between 0.5 and 1 per image, the sensitivity of the scheme could be increased approximately 5% after averaging the scores of the regions detected in at least four images. At low false-positive rate (e.g., ≤average 0.3 per image), the grouping method
International Nuclear Information System (INIS)
Simon, G.
1990-01-01
Using advanced calculation programs, the inherent behavior and response behavior of structures can reliably be predetermined. In contrast, the dynamic forces affecting a system, in particular unbalances, are often unkown. From balancing of individual rotors, only the vibration path amplitudes at the measuring points used are known. However, these may originate from quite different unbalance distributions. Using probabilistic methods, however, values for the vibrational behavior of the overall structure can be derived from this. (orig.) [de
Directory of Open Access Journals (Sweden)
Zamorska Izabela
2018-01-01
Full Text Available The subject of the paper is an application of the non-destructive vibration method for identifying the location of two cracks occurring in a beam. The vibration method is based on knowledge of a certain number of vibration frequencies of an undamaged element and the knowledge of the same number of vibration frequencies of an element with a defect. The analyzed beam, with a variable cross-sectional area, has been described according to the Bernoulli-Euler theory. To determine the values of free vibration frequencies the analytical solution, with the help of the Green’s function method, has been used.
Maekawa, Akira; Tsuji, Takashi; Takahashi, Tsuneo; Noda, Michiyasu
2014-02-01
In nuclear power plants, vibration stress of piping is frequently evaluated to prevent fatigue failure. A simple and fast measurement method is attractive to evaluate many piping systems efficiently. In this study, a method to measure the vibration stress using optical contactless displacement sensors was proposed, the prototype instrument was developed, and the instrument practicality for the method was verified. In the proposed method, light emitting diodes (LEDs) were used as measurement sensors and the vibration stress was estimated by measuring the deformation geometry of the piping caused by oscillation, which was measured as the piping curvature radius. The method provided fast and simple vibration estimates for small-bore piping. Its verification and practicality were confirmed by vibration tests using a test pipe and mock-up piping. The stress measured by both the proposed method and an accurate conventional method using strain gauges were in agreement, and it was concluded that the proposed method could be used for actual plant piping systems.
Directory of Open Access Journals (Sweden)
Polat Sendur
2017-01-01
Full Text Available Current practice of analytical and test methods related to the analysis, testing and improvement of vehicle vibrations is overviewed. The methods are illustrated on the determination and improvement of powertrain induced steering wheel vibration of a heavy commercial truck. More specifically, the transmissibility of powertrain idle vibration to cabin is investigated with respect to powertrain rigid body modes and modal alignment of the steering column/wheel system is considered. It is found out that roll mode of the powertrain is not separated from idle excitation for effective vibration isolation as well as steering wheel column mode is close to the 3rd engine excitation frequency order, which results in high vibration levels. Powertrain roll mode is optimized by tuning the powertrain mount stiffness to improve the performance. Steering column mode is also separated from the 3rd engine excitation frequency by the application of a mass absorber. It is concluded that the use of analytical and test methods to address the complex relation between design parameters and powertrain idle response is effective to optimize the system performance and evaluate the trade-offs in the vehicle design such as vibration performance and weight. Reference Number: www.asrongo.org/doi:4.2017.2.1.10
International Nuclear Information System (INIS)
Thackray, M.
1976-01-01
A method is described for producing a photographic image on a normally non-photo-receptive surface comprising the steps of 1) toning the photograph with substances which combine with or replace the silver grains so that the photograph emits either spontaneously or indirectly fission fragments or alpha particles in amounts related to the distribution of the silver grains in the photograph, 2) placing the toned photograph contiguous with the surface on which the image is to be reproduced, for sufficient time for the emissions from the photograph to reproduce the image as a radiation-damage image on the surface, the damage areas having a close positional relationship to the silver grains in the original photograph. (author)
Comparison of sEMG processing methods during whole-body vibration exercise.
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.
Nebulizer calibration using lithium chloride: an accurate, reproducible and user-friendly method.
Ward, R J; Reid, D W; Leonard, R F; Johns, D P; Walters, E H
1998-04-01
Conventional gravimetric (weight loss) calibration of jet nebulizers overestimates their aerosol output by up to 80% due to unaccounted evaporative loss. We examined two methods of measuring true aerosol output from jet nebulizers. A new adaptation of a widely available clinical assay for lithium (determined by flame photometry, LiCl method) was compared to an existing electrochemical method based on fluoride detection (NaF method). The agreement between the two methods and the repeatability of each method were examined. Ten Mefar jet nebulizers were studied using a Mefar MK3 inhalation dosimeter. There was no significant difference between the two methods (p=0.76) with mean aerosol output of the 10 nebulizers being 7.40 mg x s(-1) (SD 1.06; range 5.86-9.36 mg x s(-1)) for the NaF method and 7.27 mg x s(-1) (SD 0.82; range 5.52-8.26 mg x s(-1)) for the LiCl method. The LiCl method had a coefficient of repeatability of 13 mg x s(-1) compared with 3.7 mg x s(-1) for the NaF method. The LiCl method accurately measured true aerosol output and was considerably easier to use. It was also more repeatable, and hence more precise, than the NaF method. Because the LiCl method uses an assay that is routinely available from hospital biochemistry laboratories, it is easy to use and, thus, can readily be adopted by busy respiratory function departments.
Nam, Sun-Hwa; An, Youn-Joo
2015-12-01
This study evaluated five methods of soil inoculation using the soil alga Chlorococcum infusionum to determine the most efficient and reproducible method for promoting the growth of soil algae for toxicity testing. The five techniques included application of C. infusionum in a circle on top of the soil, to a central spot on top of the soil, to a central spot in the subsoil, to one side on top of the soil, and application divided between a circle and a central spot on top of the soil. Of these, the first method generated the greatest amount of chlorophyll fluorescence and was the method with the best reproducibility. We evaluated the applicability of this method in an assessment of the toxicity of copper and nickel to C. infusionum in two representative standard soils. Copper (20-75 mg/kg for OECD soil and 20-60 mg/kg Lufa 2.2 soil) and nickel (400-500 mg/kg for OECD soil and 60-100 mg/kg Lufa 2.2 soil) reduced the chlorophyll fluorescence of C. infusionum when the inoculation was delivered in a circle on top of both soil types. To our knowledge, this is the first study to assess the suitability of different soil algal inoculation methods for terrestrial toxicity testing. Copyright © 2015 Elsevier B.V. All rights reserved.
Fang, Yuanyuan; Zuo, Yanyan; Xia, Zhaowang
2018-03-01
The noise level is getting higher with the development of high-power marine power plant. Mechanical noise is one of the most obvious noise sources which not only affect equipment reliability, riding comfort and working environment, but also enlarge underwater noise. The periodic truss type device which is commonly applied in fields of aerospace and architectural is introduced to floating raft construction in ship. Four different raft frame structure are designed in the paper. The vibration transmissibility is taken as an evaluation index to measure vibration isolation effect. A design scheme with the best vibration isolation effect is found by numerical method. Plate type and the optimized periodic truss type raft frame structure are processed to experimental verify vibration isolation effect of the structure of the periodic raft. The experimental results demonstrate that the same quality of the periodic truss floating raft has better isolation effect than that of the plate type floating raft.
Energy Technology Data Exchange (ETDEWEB)
Wang, Dongqiang; Wu, Chengjun [Xi' an Jiaotong University, Xi' an (China)
2016-03-15
Particle damping technology is widely used in mechanical and structural systems or civil engineering to reduce vibration and suppress noise as a result of its high efficiency, simplicity and easy implementation, low cost, and energy-saving characteristic without the need for any auxiliary power equipment. Research on particle damping theory has focused on the vibration response of the particle damping structure, but the acoustic radiation of the particle damping structure is rarely investigated. Therefore, a feasible modeling method to predict the vibration response and acoustic radiation of the particle damping structure is desirable to satisfy the actual requirements in industrial practice. In this paper, a novel simulation method based on multiphase flow theory of gas particle by COMSOL multiphysics is developed to study the vibration and acoustic radiation characteristics of a cantilever rectangular plate with Particle dampers (PDs). The frequency response functions and scattered far-field sound pressure level of the plate without and with PDs under forced vibration are predicted, and the predictions agree well with the experimental results. Results demonstrate that the added PDs have a significant effect on vibration damping and noise reduction for the primary structure. The presented work in this paper shows that the theoretical work is valid, which can provide important theoretical guidance for low-noise optimization design of particle damping structure. This model also has an important reference value for the noise control of this kind of structure.
International Nuclear Information System (INIS)
Saedtler, E.
1981-01-01
The method for controlling the vibrating behaviour of primary circuit components or for a general systems control is a combination of methods of the statistic systems theory, optimum filter theory, statistic decision theory and of the pattern recognition method. It is appropriate for automatic control of complex systems and stochastic events. (DG) [de
International Nuclear Information System (INIS)
Smokvina, A.
1994-01-01
At different times following surgery and during various complications, 119 studies were performed on 57 patients. In many patients studies were repeated several times. Twenty-three studies were performed in as many patients, in whom a normal function of the transplanted kidney was established by other diagnostic methods and retrospective analysis. Comparison was made of the perfusion index results obtained by the Hilson et al. method from 1978 and the ones obtained by my own modified method, which for calculating the index also takes into account: the time difference in appearance of the initial portions of the artery and kidney curves; the positioning of the region of interest over the distal part of the aorta; the bolus injection into the arteriovenous shunt of the forearm with high specific activity of small volumes of Tc-99m labelled agents; a fast 0.5 seconds study of data collection; and a standard for normalization of numerical data. The reliability of one or the other method tested by simulated time shift of the peak of arterial curves shows that the deviation percentage from the main index value in the unmodified method is 2-5 times greater than in the modified method. The normal value of the perfusion index applying the modified method is 91-171. (author)
Alam, Md. Ashad; Fukumizu, Kenji; Wang, Yu-Ping
2016-01-01
To the best of our knowledge, there are no general well-founded robust methods for statistical unsupervised learning. Most of the unsupervised methods explicitly or implicitly depend on the kernel covariance operator (kernel CO) or kernel cross-covariance operator (kernel CCO). They are sensitive to contaminated data, even when using bounded positive definite kernels. First, we propose robust kernel covariance operator (robust kernel CO) and robust kernel crosscovariance operator (robust kern...
Dyal, Jonathan; Akampurira, Andrew; Rhein, Joshua; Morawski, Bozena M; Kiggundu, Reuben; Nabeta, Henry W; Musubire, Abdu K; Bahr, Nathan C; Williams, Darlisha A; Bicanic, Tihana; Larsen, Robert A; Meya, David B; Boulware, David R
2016-05-01
Quantitative cerebrospinal fluid (CSF) cultures provide a measure of disease severity in cryptococcal meningitis. The fungal clearance rate by quantitative cultures has become a primary endpoint for phase II clinical trials. This study determined the inter-assay accuracy of three different quantitative culture methodologies. Among 91 participants with meningitis symptoms in Kampala, Uganda, during August-November 2013, 305 CSF samples were prospectively collected from patients at multiple time points during treatment. Samples were simultaneously cultured by three methods: (1) St. George's 100 mcl input volume of CSF with five 1:10 serial dilutions, (2) AIDS Clinical Trials Group (ACTG) method using 1000, 100, 10 mcl input volumes, and two 1:100 dilutions with 100 and 10 mcl input volume per dilution on seven agar plates; and (3) 10 mcl calibrated loop of undiluted and 1:100 diluted CSF (loop). Quantitative culture values did not statistically differ between St. George-ACTG methods (P= .09) but did for St. George-10 mcl loop (Pmethods was high (r≥0.88). For detecting sterility, the ACTG-method had the highest negative predictive value of 97% (91% St. George, 60% loop), but the ACTG-method had occasional (∼10%) difficulties in quantification due to colony clumping. For CSF clearance rate, St. George-ACTG methods did not differ overall (mean -0.05 ± 0.07 log10CFU/ml/day;P= .14) on a group level; however, individual-level clearance varied. The St. George and ACTG quantitative CSF culture methods produced comparable but not identical results. Quantitative cultures can inform treatment management strategies. © The Author 2016. Published by Oxford University Press on behalf of The International Society for Human and Animal Mycology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
An extension of command shaping methods for controlling residual vibration using frequency sampling
Singer, Neil C.; Seering, Warren P.
1992-01-01
The authors present an extension to the impulse shaping technique for commanding machines to move with reduced residual vibration. The extension, called frequency sampling, is a method for generating constraints that are used to obtain shaping sequences which minimize residual vibration in systems such as robots whose resonant frequencies change during motion. The authors present a review of impulse shaping methods, a development of the proposed extension, and a comparison of results of tests conducted on a simple model of the space shuttle robot arm. Frequency shaping provides a method for minimizing the impulse sequence duration required to give the desired insensitivity.
Zhu, Qiao; Yue, Jun-Zhou; Liu, Wei-Qun; Wang, Xu-Dong; Chen, Jun; Hu, Guang-Di
2017-04-01
This work is focused on the active vibration control of piezoelectric cantilever beam, where an adaptive feedforward controller (AFC) is utilized to reject the vibration with unknown multiple frequencies. First, the experiment setup and its mathematical model are introduced. Due to that the channel between the disturbance and the vibration output is unknown in practice, a concept of equivalent input disturbance (EID) is employed to put an equivalent disturbance into the input channel. In this situation, the vibration control can be achieved by setting the control input be the identified EID. Then, for the EID with known multiple frequencies, the AFC is introduced to perfectly reject the vibration but is sensitive to the frequencies. In order to accurately identify the unknown frequencies of EID in presence of the random disturbances and un-modeled nonlinear dynamics, the time-frequency-analysis (TFA) method is employed to precisely identify the unknown frequencies. Consequently, a TFA-based AFC algorithm is proposed to the active vibration control with unknown frequencies. Finally, four cases are given to illustrate the efficiency of the proposed TFA-based AFC algorithm by experiment.
A Study of Polishing Feature of Ultrasonic-Assisted Vibration Method in Bamboo Charcoal
Directory of Open Access Journals (Sweden)
Hsin-Min Lee
2017-01-01
Full Text Available Focusing on the feature of porosity in bamboo charcoal, this study applies the ultrasonic-assisted vibration method to perform surface polishing of the silicon wafer workpiece. The self-developed bamboo charcoal polishing spindle and ultrasonic- assisted vibration mechanism are attached to a single lapping machine. In the machining process, ultrasonic vibration enables the diamond slurry to smoothly pass through the microscopic holes of bamboo charcoal; the end of the bamboo charcoalis able to continue machining on the surface of the workpiece through the grasping force which exists in the microscopic holes. Under the polishing and machining parameters of ultrasonic-assisted vibration, with a diamond slurry concentration of 0.3%, the experimental results show a polishing time of 20 min, a loading of 25 N on the workpiece surface, a spindle speed of 1200 rpm, a vibration frequency of 30 kHz and the original surface roughness value of Ra 0.252 μm equals that of a mirror-like surface at Ra 0.017 μm. These research results prove that by using bamboo charcoal and ultrasonic-assisted vibration for polishing, a very good improvement can be achieved on the workpiece surface.
A convenient and reproducible method to genetically transform bacteria of the genus Bifidobacterium
Argnani, A.; Leer, R.J.; Luijk, N. van; Pouwels, P.H.
1996-01-01
A protocol was developed for the introduction of foreign plasmid DNA into various Bifidobacterium strains. The method, which is applicable to all Bifidobacterium species tested so far, is based on electroporation of bacteria made competent by preincubation in electroporation buffer for several hours
Shinogle-Decker, Heather; Martinez-Rivera, Noraida; O'Brien, John; Powell, Richard D.; Joshi, Vishwas N.; Connell, Samuel; Rosa-Molinar, Eduardo
2018-02-01
A new correlative Förster Resonance Energy Transfer (FRET) microscopy method using FluoroNanogold™, a fluorescent immunoprobe with a covalently attached Nanogold® particle (1.4nm Au), overcomes resolution limitations in determining distances within synaptic nanoscale architecture. FRET by acceptor photobleaching has long been used as a method to increase fluorescence resolution. The transfer of energy from a donor to an acceptor generally occurs between 10-100Å, which is the relative distance between the donor molecule and the acceptor molecule. For the correlative FRET microscopy method using FluoroNanogold™, we immuno-labeled GFP-tagged-HeLa-expressing Connexin 35 (Cx35) with anti-GFP and with anti-Cx35/36 antibodies, and then photo-bleached the Cx before processing the sample for electron microscopic imaging. Preliminary studies reveal the use of Alexa Fluor® 594 FluoroNanogold™ slightly increases FRET distance to 70Å, in contrast to the 62.5Å using AlexaFluor 594®. Preliminary studies also show that using a FluoroNanogold™ probe inhibits photobleaching. After one photobleaching session, Alexa Fluor 594® fluorescence dropped to 19% of its original fluorescence; in contrast, after one photobleaching session, Alexa Fluor 594® FluoroNanogold™ fluorescence dropped to 53% of its original intensity. This result confirms that Alexa Fluor 594® FluoroNanogold™ is a much better donor probe than is Alexa Fluor 594®. The new method (a) creates a double confirmation method in determining structure and orientation of synaptic architecture, (b) allows development of a two-dimensional in vitro model to be used for precise testing of multiple parameters, and (c) increases throughput. Future work will include development of FluoroNanogold™ probes with different sizes of gold for additional correlative microscopy studies.
A REVIEW OF VIBRATION MACHINE DIAGNOSTICS BY USING ARTIFICIAL INTELLIGENCE METHODS
Directory of Open Access Journals (Sweden)
Grover Zurita
2016-09-01
Full Text Available In the industry, gears and rolling bearings failures are one of the foremost causes of breakdown in rotating machines, reducing availability time of the production and resulting in costly systems downtime. Therefore, there are growing demands for vibration condition based monitoring of gears and bearings, and any method in order to improve the effectiveness, reliability, and accuracy of the bearing faults diagnosis ought to be evaluated. In order to perform machine diagnosis efficiently, researchers have extensively investigated different advanced digital signal processing techniques and artificial intelligence methods to accurately extract fault characteristics from vibration signals. The main goal of this article is to present the state-of-the-art development in vibration analysis for machine diagnosis based on artificial intelligence methods.
Niebuhr, Cole
2018-04-01
Papers published in the astronomical community, particularly in the field of double star research, often contain plots that display the positions of the component stars relative to each other on a Cartesian coordinate plane. Due to the complexities of plotting a three-dimensional orbit into a two-dimensional image, it is often difficult to include an accurate reproduction of the orbit for comparison purposes. Methods to circumvent this obstacle do exist; however, many of these protocols result in low-quality blurred images or require specific and often expensive software. Here, a method is reported using Microsoft Paint and Microsoft Excel to produce high-quality images with an accurate reproduction of a partial orbit.
Efficient and reproducible synthesis of [1-{sup 11}C]acetyl chloride using the loop method
Energy Technology Data Exchange (ETDEWEB)
Arai, Takuya [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); Zhang, Ming-Rong [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)], E-mail: zhang@nirs.go.jp; Ogawa, Masanao [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan); SHI Accelerator Service Co. Ltd., 1-17-6 Osaki, Shinagawa-ku, Tokyo 141-8686 (Japan); Fukumura, Toshimitsu; Kato, Koichi; Suzuki, Kazutoshi [Department of Molecular Probes, Molecular Imaging Center, National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba 263-8555 (Japan)
2009-02-15
[1-{sup 11}C]Acetyl chloride ([{sup 11}C]AcCl), an important [{sup 11}C]acylating agent, was synthesized by reacting [{sup 11}C]CO{sub 2} with methylmagnesium bromide coated on the inner surface of a polyethylene loop (loop method). By optimizing the reaction conditions and synthesis parameters, [1-{sup 11}C]phenylacetate and [1-{sup 11}C]benzylacetate were produced from [{sup 11}C]AcCl in high radiochemical yield and specific activity.
General principles of control method of passenger car bodies bending vibration parameters
Skachkov, A. N.; Samoshkin, S. L.; Korshunov, S. D.; Kobishchanov, V. V.; Antipin, D. Ya
2018-03-01
Weight reduction of passenger cars is a promising direction of reducing the cost of their production and increasing transportation profitability. One way to reduce the weight of passenger cars is the lightweight metal body design by means of using of high-strength aluminum alloys, low-alloy and stainless steels. However, it has been found that the limit of the lightweight metal body design is not determined by the total mode of deformation, but its flexural rigidity, as the latter influences natural frequencies of body bending vibrations. With the introduction of mandatory certification for compliance with the Customs Union technical regulations, the following index was confirmed: “first natural frequency of body bending vibrations in the vertical plane”. This is due to the fact that vibration, noise and car motion depend on this index. To define the required indexes, the principles of the control method of bending vibration parameters of passenger car bodies are proposed in this paper. This method covers all stages of car design – development of design documentation, manufacturing and testing experimental and pilot models, launching the production. The authors also developed evaluation criteria and the procedure of using the results for introduction of control method of bending vibration parameters of passenger car bodies.
Directory of Open Access Journals (Sweden)
WANG Minhao
2017-08-01
Full Text Available Plate structures with openings are common in many engineering structures. The study of the vibration characteristics of such structures is directly related to the vibration reduction, noise reduction and stability analysis of an overall structure. This paper conducts research into the free vibration characteristics of a thin elastic plate with a rectangular opening parallel to the plate in an arbitrary position. We use the improved Fourier series to represent the displacement tolerance function of the rectangular plate with an opening. We can divide the plate into an eight zone plate to simplify the calculation. We then use linear springs, which are uniformly distributed along the boundary, to simulate the classical boundary conditions and the boundary conditions of the boundaries between the regions. According to the energy functional and variational method, we can obtain the overall energy functional. We can also obtain the generalized eigenvalue matrix equation by studying the extremum of the unknown improved Fourier series expansion coefficients. We can then obtain the natural frequencies and corresponding vibration modes of the rectangular plate with an opening by solving the equation. We then compare the calculated results with the finite element method to verify the accuracy and effectiveness of the method proposed in this paper. Finally, we research the influence of the boundary condition, opening size and opening position on the vibration characteristics of a plate with an opening. This provides a theoretical reference for practical engineering application.
Loendersloot, Richard; Ooijevaar, T.H.; Warnet, Laurent; Akkerman, Remko; de Boer, Andries; Meguid, S.A.; Gomes, J.F.S.
2009-01-01
The feasibility of a vibration based damage identification method is investigated. The Modal Strain Energy method is applied to a T–beam structure. The dynamic response of an intact structure and a damaged, delaminated structure is analysed employing a commercially available Finite Element package.
Energy Technology Data Exchange (ETDEWEB)
Lee, M; Woo, B; Kim, J [Seoul National University, Seoul (Korea, Republic of); Jamshidi, N; Kuo, M [UCLA School of Medicine, Los Angeles, CA (United States)
2015-06-15
Purpose: Objective and reliable quantification of imaging phenotype is an essential part of radiogenomic studies. We compared the reproducibility of two semi-automatic segmentation methods for quantitative image phenotyping in magnetic resonance imaging (MRI) of glioblastoma multiforme (GBM). Methods: MRI examinations with T1 post-gadolinium and FLAIR sequences of 10 GBM patients were downloaded from the Cancer Image Archive site. Two semi-automatic segmentation tools with different algorithms (deformable model and grow cut method) were used to segment contrast enhancement, necrosis and edema regions by two independent observers. A total of 21 imaging features consisting of area and edge groups were extracted automatically from the segmented tumor. The inter-observer variability and coefficient of variation (COV) were calculated to evaluate the reproducibility. Results: Inter-observer correlations and coefficient of variation of imaging features with the deformable model ranged from 0.953 to 0.999 and 2.1% to 9.2%, respectively, and the grow cut method ranged from 0.799 to 0.976 and 3.5% to 26.6%, respectively. Coefficient of variation for especially important features which were previously reported as predictive of patient survival were: 3.4% with deformable model and 7.4% with grow cut method for the proportion of contrast enhanced tumor region; 5.5% with deformable model and 25.7% with grow cut method for the proportion of necrosis; and 2.1% with deformable model and 4.4% with grow cut method for edge sharpness of tumor on CE-T1W1. Conclusion: Comparison of two semi-automated tumor segmentation techniques shows reliable image feature extraction for radiogenomic analysis of GBM patients with multiparametric Brain MRI.
International Nuclear Information System (INIS)
Lee, M; Woo, B; Kim, J; Jamshidi, N; Kuo, M
2015-01-01
Purpose: Objective and reliable quantification of imaging phenotype is an essential part of radiogenomic studies. We compared the reproducibility of two semi-automatic segmentation methods for quantitative image phenotyping in magnetic resonance imaging (MRI) of glioblastoma multiforme (GBM). Methods: MRI examinations with T1 post-gadolinium and FLAIR sequences of 10 GBM patients were downloaded from the Cancer Image Archive site. Two semi-automatic segmentation tools with different algorithms (deformable model and grow cut method) were used to segment contrast enhancement, necrosis and edema regions by two independent observers. A total of 21 imaging features consisting of area and edge groups were extracted automatically from the segmented tumor. The inter-observer variability and coefficient of variation (COV) were calculated to evaluate the reproducibility. Results: Inter-observer correlations and coefficient of variation of imaging features with the deformable model ranged from 0.953 to 0.999 and 2.1% to 9.2%, respectively, and the grow cut method ranged from 0.799 to 0.976 and 3.5% to 26.6%, respectively. Coefficient of variation for especially important features which were previously reported as predictive of patient survival were: 3.4% with deformable model and 7.4% with grow cut method for the proportion of contrast enhanced tumor region; 5.5% with deformable model and 25.7% with grow cut method for the proportion of necrosis; and 2.1% with deformable model and 4.4% with grow cut method for edge sharpness of tumor on CE-T1W1. Conclusion: Comparison of two semi-automated tumor segmentation techniques shows reliable image feature extraction for radiogenomic analysis of GBM patients with multiparametric Brain MRI
International Nuclear Information System (INIS)
Devaux, J.Y.; Mazelier, L.; Lefkopoulos, D.
1997-01-01
We have earlier shown that the method of singular value decomposition (SVD) allows the image reconstruction in single-photon-tomography with precision higher than the classical method of filtered back-projections. Actually, the establishing of an elementary response matrix which incorporates both the photon attenuation phenomenon, the scattering, the translation non-invariance principle and the detector response, allows to take into account the totality of physical parameters of acquisition. By an non-consecutive optimized truncation of the singular values we have obtained a significant improvement in the efficiency of the regularization of bad conditioning of this problem. The present study aims at verifying the stability of this truncation under modifications of acquisition conditions. Two series of parameters were tested, first, those modifying the geometry of acquisition: the influence of rotation center, the asymmetric disposition of the elementary-volume sources against the detector and the precision of rotation angle, and secondly, those affecting the correspondence between the matrix and the space to be reconstructed: the effect of partial volume and a noise propagation in the experimental model. For the parameters which introduce a spatial distortion, the alteration of reconstruction has been, as expected, comparable to that observed with the classical reconstruction and proportional with the amplitude of shift from the normal one. In exchange, for the effect of partial volume and of noise, the study of truncation signature revealed a variation in the optimal choice of the conserved singular values but with no effect on the global precision of reconstruction
Komolafe, Olusegun O; Melani, Armando G; Véo, Carlos A; Denadai, Marcos V; de Oliveira, Júnea C
2012-10-01
Laparoscopic resection for colorectal cancer by appropriately skilled surgeons is now accepted as safe and oncologically sound. Much of the contemporary debate in this area is regarding appropriate training of surgeons, as there is a steep learning curve. Arguably, the most difficult aspect of laparoscopic colon resection is mobilization of the transverse colon, with division of the middle colic artery. Mobilizing the transverse colon is necessary for many colonic resections, including "introductory" procedures. Our department has a consistent, sequential method for mobilization of the transverse colon with proximal isolation and ligation of the middle colic artery as indicated. This involves using the head, or distal body, of the pancreas as a landmark, for right-sided and left-sided resections, respectively. We believe that this particular methodology is easy to learn and surgically efficient. We also discuss some particular intraoperative problems and scenarios, with suggested solutions.
Standardization of Laser Methods and Techniques for Vibration Measurements and Calibrations
International Nuclear Information System (INIS)
Martens, Hans-Juergen von
2010-01-01
The realization and dissemination of the SI units of motion quantities (vibration and shock) have been based on laser interferometer methods specified in international documentary standards. New and refined laser methods and techniques developed by national metrology institutes and by leading manufacturers in the past two decades have been swiftly specified as standard methods for inclusion into in the series ISO 16063 of international documentary standards. A survey of ISO Standards for the calibration of vibration and shock transducers demonstrates the extended ranges and improved accuracy (measurement uncertainty) of laser methods and techniques for vibration and shock measurements and calibrations. The first standard for the calibration of laser vibrometers by laser interferometry or by a reference accelerometer calibrated by laser interferometry (ISO 16063-41) is on the stage of a Draft International Standard (DIS) and may be issued by the end of 2010. The standard methods with refined techniques proved to achieve wider measurement ranges and smaller measurement uncertainties than that specified in the ISO Standards. The applicability of different standardized interferometer methods to vibrations at high frequencies was recently demonstrated up to 347 kHz (acceleration amplitudes up to 350 km/s 2 ). The relative deviations between the amplitude measurement results of the different interferometer methods that were applied simultaneously, differed by less than 1% in all cases.
International Nuclear Information System (INIS)
Hadengue, A.; Lee, S.S.; Koshy, A.; Girod, C.; Lebrec, D.
1988-01-01
To determine the reproducibility of splanchnic blood flow measurements by the microsphere method in rats with portal hypertension and the effects of laparotomy with portal vein cannulation, eight groups of 10 rats were studied. Microspheres were labelled with 113 Sn or 141 Ce. Laparotomy with portal cannulation had no significant effect in sham-operated rats. In awake portal hypertensive rats, cardiac output and splanchnic blood flow were lower in portal vein cannulated rats compared with those of non-cannulated animals. In anesthetized portal hypertensive rats blood flows were unaffected by portal cannulation, but arterial pressure and heart rate were elevated. Anesthesia also decreased portal pressure in portal hypertensive rats. We conclude that the microsphere method remains reproducible in portal hypertensive rat models. Laparotomy with portal cannulation can alter systemic and splanchnic hemodynamics in portal hypertensive rats; these effects can also be changed during pentobarbital anesthesia. Regional blood flow measurements in portal hypertensive rats should be performed in animals without portal cannulation and preferably in the awake state
Jafarifar, Elham; Hajialyani, Marziyeh; Akbari, Mona; Rahimi, Masoud; Shokoohinia, Yalda; Fattahi, Ali
2017-09-01
The aim of the present study is to prepare risperidone-loaded poly lactic-co-glycolic acid (PLGA) microspheres within microfluidic system and to achieve a formulation with uniform size and monotonic and reproducible release profile. In comparison to batch method, T-junction and serpentine chips were utilized and optimizing study was carried out at different processing parameters (e.g. PLGA and surfactant concentration and flow rates ratio of outer to inner phase). The computational fluid dynamic (CFD) modeling was performed, and loading and release study were carried out. CFD simulation indicates that increasing the flow rate of aqueous phase cause to decrease the droplet size, while the change in size of microspheres did not follow a specific pattern in the experimental results. The most uniform microspheres and narrowest standard deviation (66.79 μm ± 3.32) were achieved using T-junction chip, 1% polyvinylalcohol, 1% PLGA and flow rates ratio of 20. The microfluidic-assisted microspheres were more uniform with narrower size distribution. The release of risperidone from microspheres produced by the microfluidic method was more reproducible and closer to zero-order kinetic model. The release profile of formulation with 2:1 drug-to-polymer ratio was the most favorable release, in which 41.85% release could be achieved during 24 days.
Cartmell, Matthew P.
2016-09-01
The Editor wishes to make the reader aware that the paper "A new method for predicting nonlinear structural vibrations induced by ground impact loading" by Jun Liu, Yu Zhang, Bin Yun, Journal of Sound and Vibration, 331 (2012) 2129-2140, did not contain a direct citation of the fundamental and original work in this field by Dr. Mark Svinkin. The Editor regrets that this omission was not noted at the time that the above paper was accepted and published.
International Nuclear Information System (INIS)
Kurt, M.
2005-01-01
The molecular geometry and vibrational frequencies of 6-methylquinoline(6MQ) and 8-methylquinolines(8MQ) in the ground state have been calculated by using the Hartree-Fock and density functional methods (B3LYP and BLYP) with 6-31G (d) as the basis set. The optimized geometric bond lengths obtained by using B3LYP and bond angles obtained by BLYP were given corresponding experimental values of similar molecule. Comparison of the observed fundamental vibrational frequencies of these molecules and calculated results by density functional B3LYP, BLYP and Hartree-Fock methods indicates that B3LYP is superior to the scaled Hartree- Fock and BLYP approach for molecular vibrational problems
Application of Time Delay Consideration on Bridge Vibration Control Method with Active Tendons
Directory of Open Access Journals (Sweden)
Lezin Seba MINSILI
2010-12-01
Full Text Available For many years bridge structures have been designed or constructed as passive structures that rely on their mass and solidity to resist external forces, while being incapable of adapting to the dynamics of an ever-changing environment. When the rigidity assumption is not met in particular for high-rise structures like bridge towers, a proper dynamic model should be established and conclusions made on the differential vibration of the tower when it is investigated out of the bridge system. The present work outlines a vibration control method by tendons on the tower of cable supported structures considering time delay effects, based on the discrete-time Linearization of the Feedback Gain Matrix. The efficiency of this vibration control method first proposed on the design process of a local bridge in Cameroon, is more compatible to the control of civil structures and is of great interest in accordance with simulation results.
Hydroelastic model of PWR reactor internals SAFRAN 1 - Validation of a vibration calculation method
International Nuclear Information System (INIS)
Epstein, A.; Gibert, R.J.; Jeanpierre, F.; Livolant, M.
1978-01-01
The SAFRAN 1 test loop consists of an hydroelastic similitude of a 1/8 scale model of a 3 loop P.W.R. Vibrations of the main internals (thermal shield and core barrel) and pressure fluctuations in water thin sections between vessel and internals, and in inlet and outlet pipes, have been measured. The calculation method consists of: an evaluation of the main vibration and acoustic sources owing to the flow (unsteady jet impingement on the core barrel, turbulent flow in a water thin section). A calculation of the internal modal parameters taking into account the inertial effects of fluid (the computer codes AQUAMODE and TRISTANA have been used). A calculation of the acoustic response of the circuit (the computer code VIBRAPHONE has been used). The good agreement between the calculation and the experimental results allows using this method with better security for the prediction of the vibration levels of full scale P.W.R. internals
Xiao, Zhongxiu
2018-04-01
A Method of Measuring and Correcting Tilt of Anti - vibration Wind Turbines Based on Screening Algorithm is proposed in this paper. First of all, we design a device which the core is the acceleration sensor ADXL203, the inclination is measured by installing it on the tower of the wind turbine as well as the engine room. Next using the Kalman filter algorithm to filter effectively by establishing a state space model for signal and noise. Then we use matlab for simulation. Considering the impact of the tower and nacelle vibration on the collected data, the original data and the filtering data are classified and stored by the Screening algorithm, then filter the filtering data to make the output data more accurate. Finally, we eliminate installation errors by using algorithm to achieve the tilt correction. The device based on this method has high precision, low cost and anti-vibration advantages. It has a wide range of application and promotion value.
Directory of Open Access Journals (Sweden)
Krzysztof J Gorgolewski
2017-03-01
Full Text Available The rate of progress in human neurosciences is limited by the inability to easily apply a wide range of analysis methods to the plethora of different datasets acquired in labs around the world. In this work, we introduce a framework for creating, testing, versioning and archiving portable applications for analyzing neuroimaging data organized and described in compliance with the Brain Imaging Data Structure (BIDS. The portability of these applications (BIDS Apps is achieved by using container technologies that encapsulate all binary and other dependencies in one convenient package. BIDS Apps run on all three major operating systems with no need for complex setup and configuration and thanks to the comprehensiveness of the BIDS standard they require little manual user input. Previous containerized data processing solutions were limited to single user environments and not compatible with most multi-tenant High Performance Computing systems. BIDS Apps overcome this limitation by taking advantage of the Singularity container technology. As a proof of concept, this work is accompanied by 22 ready to use BIDS Apps, packaging a diverse set of commonly used neuroimaging algorithms.
A numerical method to calculate flow-induced vibrations in a turbulent flow
International Nuclear Information System (INIS)
Sadaoka, Noriyuki; Umegaki, Kikuo
1993-01-01
An unsteady fluid force on structures in a turbulent flow can cause their vibration. The phenomenon is the most important among various flow-induced vibrations and it is an important subject in design nuclear plant components such as heat exchangers. A new approach to simulate flow-induced vibrations is introduced. A fully coupled analysis of fluid-structure interaction has been realized in a turbulent flow field by integrating the following calculational steps: (a) solving turbulent flow by a direct simulation method where the ALE (arbitrary Lagrangian Eulerian) type approximation is adopted to take account of structure displacements; (b) estimating fluid force on structures by integrating fluid pressure and shear stress; (c) calculating dynamic response of structures and determining the amount of displacement; (d) regenerate curvilinear grids for new geometry using the boundary-fitted coordinate transformation method. Forced vibration of a circular cylinder in a cross flow were successfully simulated and the synchronization phenomena between Karman-vortices and cylinder vibrations were clearly seen
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
Directory of Open Access Journals (Sweden)
A. Khavanin
2014-07-01
Conclusion: Investigation of the result obtained from Basic method and VDV method manifested different amounts of vibration exposure in a way that VDV predicts higher level of risk, compared to basic method. The results shows that some presented indicators can not presented the safe zone in human vibration evaluations.
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.
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.
Method of monitoring fuel-rod vibrations in a nuclear fuel reactor
International Nuclear Information System (INIS)
Kawamura, Makoto; Takai, Katsuaki.
1985-01-01
Purpose: To monitor the vibration modes of fuel rods continuously and on real time during operation of a PWR type nuclear reactor. Method: Vibrations of fuel rods during reactor operation are mainly caused by the lateral flow of coolants flowing through the gaps at the joints of reactor core buffle plates into a reactor core and fretting damages may possibly be caused to the fuel rod support portions due to the vibrations. In view of the above, self-powered detectors are disposed at a plurality of axial positions for the respective peripheral fuel assemblies in adjacent with the buffle plates and the detection signals from neutron detectors, that is, the fluctuations in neutrons are subjected to a frequency analysis during the operation period. The neutron detectors are disposed at the periphery of the reactor core, because the fuel assemblies disposed at the peripheral portion directly undergo the lateral flow from the joints of the buffle plates and vibrates most violently. Thus, the vibration situations can be monitored continuously, in a three demensional manner and on real time. (Moriyama, K.)
Improved time-dependent harmonic oscillator method for vibrationally inelastic collisions
International Nuclear Information System (INIS)
DePristo, A.E.
1985-01-01
A quantal solution to vibrationally inelastic collisions is presented based upon a linear expansion of the interaction potential around the time-dependent classical positions of all translational and vibrational degrees of freedom. The full time-dependent wave function is a product of a Gaussian translational wave packet and a multidimensional harmonic oscillator wave function, both centered around the appropriate classical position variables. The computational requirements are small since the initial vibrational coordinates are the equilibrium values in the classical trajectory (i.e., phase space sampling does not occur). Different choices of the initial width of the translational wave packet and the initial classical translational momenta are possible, and two combinations are investigated. The first involves setting the initial classical momenta equal to the quantal expectation value, and varying the width to satisfy normalization of the transition probability matrix. The second involves adjusting the initial classical momenta to ensure detailed balancing for each set of transitions, i→f and f→i, and varying the width to satisfy normalization. This choice illustrates the origin of the empirical correction of using the arithmetic average momenta as the initial classical momenta in the forced oscillator approximation. Both methods are tested for the collinear collision systems CO 2 --(He, Ne), and are found to be accurate except for near-resonant vibration--vibration exchange at low initial kinetic energies
Vibration test of spherical shell structure and replacing method into mathematical model
International Nuclear Information System (INIS)
Takayanagi, M.; Suzuki, S.; Okamura, T.; Haas, E.E.; Krutzik, N.J.
1989-01-01
To verify the beam-type and oval-type vibratory characteristics of a spherical shell structure, two test specimens were made and vibration tests were carried out. Results of these tests are compared with results of detailed analyses using 3-D FEM and 2-D axisymmetric FEM models. The analytical results of overall vibratory characteristics are in good agreement with the test results, has been found that the effect of the attached mass should be considered in evaluating local vibration. The replacing method into equivalent beam model is proposed
Study on Vibration Reduction Method for a Subway Station in Soft Ground
Directory of Open Access Journals (Sweden)
Xian-Feng Ma
2017-01-01
Full Text Available With the rapid development of metro system in urban areas, vibration and its impact on adjacent structures caused by metro operation have drawn much attention of researches and worries relating to it have risen. This paper analyzed the vibration attenuation and the environment impact by a case study of a subway station in soft ground with adjacent laboratory building. A method of setting a compound separation barrier surrounding the station is checked and different materials used in the barrier have been tried and tested through numerical analysis. Key parameters of the material and the effects of vibration reduction are studied with the purpose that similar methodology and findings can be referenced in future practices.
Nondestructive assessment of single-span timber bridges using a vibration- based method
Xiping Wang; James P. Wacker; Angus M. Morison; John W. Forsman; John R. Erickson; Robert J. Ross
2005-01-01
This paper describes an effort to develop a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the natural frequency of single-span timber bridges in the laboratory and field. An analytical model based on simple beam theory was proposed to represent the relationship...
Determining shear modulus of thin wood composite materials using a cantilever beam vibration method
Cheng Guan; Houjiang Zhang; John F. Hunt; Haicheng Yan
2016-01-01
Shear modulus (G) of thin wood composite materials is one of several important indicators that characterizes mechanical properties. However, there is not an easy method to obtain this value. This study presents the use of a newly developed cantilever beam free vibration test apparatus to detect in-plane G of thin wood composite...
Nondestructive assessment of timber bridges using a vibration-based method
Xiping Wang; James P. Wacker; Robert J. Ross; Brian K. Brashaw
2005-01-01
This paper describes an effort to develop a global dynamic testing technique for evaluating the overall stiffness of timber bridge superstructures. A forced vibration method was used to measure the natural frequency of single-span timber bridges in the laboratory and field. An analytical model based on simple beam theory was proposed to represent the relationship...
Commutator perturbation method in the study of vibrational-rotational spectra of diatomic molecules
International Nuclear Information System (INIS)
Matamala-Vasquez, A.; Karwowski, J.
2000-01-01
The commutator perturbation method, an algebraic version of the Van Vleck-Primas perturbation method, expressed in terms of ladder operators, has been applied to solving the eigenvalue problem of the Hamiltonian describing the vibrational-rotational motion of a diatomic molecule. The physical model used in this work is based on Dunham's approach. The method facilitates obtaining both energies and eigenvectors in an algebraic way
International Nuclear Information System (INIS)
Yonekawa, Yutaka; Fukunaga, Tatsuya
2008-01-01
The main rotary machine is often an intermittent driving machine in the nuclear plant. On the other hand, it was a problem for the vibration method to detect the vibration when rotating, and very to achieve the vibration tendency management for the equipment that did not rotate though it positively worked on the introduction of the equipment diagnosis technology by the vibration method of the rotation equipment in the nuclear plant. This time, because the tendency management system of the intermittent driving equipment is developed, and the tendency management was achieved, it introduces the outline and an actual case. (author)
McAlinden, Colm; Khadka, Jyoti; Pesudovs, Konrad
2011-07-01
The ever-expanding choice of ocular metrology and imaging equipment has driven research into the validity of their measurements. Consequently, studies of the agreement between two instruments or clinical tests have proliferated in the ophthalmic literature. It is important that researchers apply the appropriate statistical tests in agreement studies. Correlation coefficients are hazardous and should be avoided. The 'limits of agreement' method originally proposed by Altman and Bland in 1983 is the statistical procedure of choice. Its step-by-step use and practical considerations in relation to optometry and ophthalmology are detailed in addition to sample size considerations and statistical approaches to precision (repeatability or reproducibility) estimates. Ophthalmic & Physiological Optics © 2011 The College of Optometrists.
International Nuclear Information System (INIS)
Needell, Steven D.; Borzykowski, Ross M.; Carreira, Dominic S.; Kozy, John
2014-01-01
To devise a simple, reproducible method of using CT data to measure anterior acetabular coverage that results in values analogous to metrics derived from false-profile radiographs. Volume CT images were used to generate simulated false-profile radiographs and cross-sectional false-profile views by angling a multiplanar reformat 115 through the affected acetabulum relative to a line tangential to the posterior margin of the ischial tuberosities. The anterolateral margin of the acetabulum was localized on the CT false-profile view corresponding with the cranial opening of the acetabular roof. Anterior center edge angle (CEA) was measured between a vertical line passing through the center of the femoral head and a line connecting the center of the femoral head with the anterior edge of the condensed line of the acetabulum (sourcil). Anterior CEA values measured on CT false-profile views of 38 symptomatic hips were compared with values obtained on simulated and projection false-profile radiographs. The CT false-profile view produces a cross-sectional image in the same obliquity as false-profile radiographs. Anterior CEA measured on CT false-profile views were statistically similar to values obtained with false-profile radiographs. CT technologists quickly mastered the technique of generating this view. Inter-rater reliability indicated this method to be highly reproducible. The CT false-profile view is simple to generate and anterior CEA measurements derived from it are similar to those obtained using well-positioned false-profile radiographs. Utilization of CT to assess hip geometry enables precise control of pelvic inclination, eliminates projectional errors, and minimizes limitations of image quality inherent to radiography. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Needell, Steven D.; Borzykowski, Ross M. [Boca Radiology Group, Boca Raton, FL (United States); Carreira, Dominic S.; Kozy, John [Broward Health Orthopedics and Sports Medicine, Fort Lauderdale, FL (United States)
2014-11-15
To devise a simple, reproducible method of using CT data to measure anterior acetabular coverage that results in values analogous to metrics derived from false-profile radiographs. Volume CT images were used to generate simulated false-profile radiographs and cross-sectional false-profile views by angling a multiplanar reformat 115 through the affected acetabulum relative to a line tangential to the posterior margin of the ischial tuberosities. The anterolateral margin of the acetabulum was localized on the CT false-profile view corresponding with the cranial opening of the acetabular roof. Anterior center edge angle (CEA) was measured between a vertical line passing through the center of the femoral head and a line connecting the center of the femoral head with the anterior edge of the condensed line of the acetabulum (sourcil). Anterior CEA values measured on CT false-profile views of 38 symptomatic hips were compared with values obtained on simulated and projection false-profile radiographs. The CT false-profile view produces a cross-sectional image in the same obliquity as false-profile radiographs. Anterior CEA measured on CT false-profile views were statistically similar to values obtained with false-profile radiographs. CT technologists quickly mastered the technique of generating this view. Inter-rater reliability indicated this method to be highly reproducible. The CT false-profile view is simple to generate and anterior CEA measurements derived from it are similar to those obtained using well-positioned false-profile radiographs. Utilization of CT to assess hip geometry enables precise control of pelvic inclination, eliminates projectional errors, and minimizes limitations of image quality inherent to radiography. (orig.)
An active vibration control method of bridge structures by the ...
African Journals Online (AJOL)
The 'Linearization of Feedback Gain Matrix' (LFGM) method proposed by the author to achieve this objective is obtained by activating some useful components of the Riccati matrix while others are strongly attenuated according to the expected output-results and requirements of control mechanism. The present algorithm is ...
Cheng Guan; Houjiang Zhang; Lujing Zhou; Xiping Wang
2015-01-01
A vibration testing method based on free vibration theory in a ââfreeâfreeâ support condition was investigated for evaluating the modulus of elasticity (MOE) of full-size wood composite panels (WCPs). Vibration experiments were conducted on three types of WCPs (medium density fibreboard, particleboard, and plywood) to determine the dynamic MOE of the panels. Static...
DEFF Research Database (Denmark)
Borgbjerg, Jens; Bøgsted, Martin; Lindholt, Jes S
2018-01-01
Objectives: Controversy exists regarding optimal caliper placement in ultrasound assessment of maximum abdominal aortic diameter. This study aimed primarily to determine reproducibility of caliper placement in relation to the aortic wall with the three principal methods: leading to leading edge...
Guo, Wei; Tse, Peter W.
2013-01-01
Today, remote machine condition monitoring is popular due to the continuous advancement in wireless communication. Bearing is the most frequently and easily failed component in many rotating machines. To accurately identify the type of bearing fault, large amounts of vibration data need to be collected. However, the volume of transmitted data cannot be too high because the bandwidth of wireless communication is limited. To solve this problem, the data are usually compressed before transmitting to a remote maintenance center. This paper proposes a novel signal compression method that can substantially reduce the amount of data that need to be transmitted without sacrificing the accuracy of fault identification. The proposed signal compression method is based on ensemble empirical mode decomposition (EEMD), which is an effective method for adaptively decomposing the vibration signal into different bands of signal components, termed intrinsic mode functions (IMFs). An optimization method was designed to automatically select appropriate EEMD parameters for the analyzed signal, and in particular to select the appropriate level of the added white noise in the EEMD method. An index termed the relative root-mean-square error was used to evaluate the decomposition performances under different noise levels to find the optimal level. After applying the optimal EEMD method to a vibration signal, the IMF relating to the bearing fault can be extracted from the original vibration signal. Compressing this signal component obtains a much smaller proportion of data samples to be retained for transmission and further reconstruction. The proposed compression method were also compared with the popular wavelet compression method. Experimental results demonstrate that the optimization of EEMD parameters can automatically find appropriate EEMD parameters for the analyzed signals, and the IMF-based compression method provides a higher compression ratio, while retaining the bearing defect
A review on fatigue life prediction methods for anti-vibration rubber materials
Directory of Open Access Journals (Sweden)
Xiaoli WANG
2016-08-01
Full Text Available Anti-vibration rubber, because of its superior elasticity, plasticity, waterproof and trapping characteristics, is widely used in the automotive industry, national defense, construction and other fields. The theory and technology of predicting fatigue life is of great significance to improve the durability design and manufacturing of anti-vibration rubber products. According to the characteristics of the anti-vibration rubber products in service, the technical difficulties for analyzing fatigue properties of anti-vibration rubber materials are pointed out. The research progress of the fatigue properties of rubber materials is reviewed from three angles including methods of fatigue crack initiation, fatigue crack propagation and fatigue damage accumulation. It is put forward that some nonlinear characteristics of rubber under fatigue loading, including the Mullins effect, permanent deformation and cyclic stress softening, should be considered in the further study of rubber materials. Meanwhile, it is indicated that the fatigue damage accumulation method based on continuum damage mechanics might be more appropriate to solve fatigue damage and life prediction problems for complex rubber materials and structures under fatigue loading.
Clarke, Peter; Varghese, Philip; Goldstein, David
2018-01-01
A discrete velocity method is developed for gas mixtures of diatomic molecules with both rotational and vibrational energy states. A full quantized model is described, and rotation-translation and vibration-translation energy exchanges are simulated using a Larsen-Borgnakke exchange model. Elastic and inelastic molecular interactions are modeled during every simulated collision to help produce smooth internal energy distributions. The method is verified by comparing simulations of homogeneous relaxation by our discrete velocity method to numerical solutions of the Jeans and Landau-Teller equations, and to direct simulation Monte Carlo. We compute the structure of a 1D shock using this method, and determine how the rotational energy distribution varies with spatial location in the shock and with position in velocity space.
Reproducibility of a semi-automatic method for 6-point vertebral morphometry in a multi-centre trial
International Nuclear Information System (INIS)
Guglielmi, Giuseppe; Stoppino, Luca Pio; Placentino, Maria Grazia; D'Errico, Francesco; Palmieri, Francesco
2009-01-01
Purpose: To evaluate the reproducibility of a semi-automated system for vertebral morphometry (MorphoXpress) in a large multi-centre trial. Materials and methods: The study involved 132 clinicians (no radiologist) with different levels of experience across 20 osteo-centres in Italy. All have received training in using MorphoXpress. An expert radiologist was also involved providing data used as standard of reference. The test image originate from normal clinical activity and represent a variety of normal, under and over exposed films, indicating both normal anatomy and vertebral deformities. The image was represented twice to the clinicians in a random order. Using the software, the clinicians initially marked the midpoints of the upper and lower vertebrae to include as many of the vertebrae (T5-L4) as practical within each given image. MorphoXpress performs the localisation of all morphometric points based on statistical model-based vision system. Intra-operator as well inter-operator measurement of agreement was calculated using the coefficient of variation and the mean and standard deviation of the difference of two measurements to check their agreement. Results: The overall intra-operator mean differences in vertebral heights is 1.61 ± 4.27% (1 S.D.). The overall intra-operator coefficient of variation is 3.95%. The overall inter-operator mean differences in vertebral heights is 2.93 ± 5.38% (1 S.D.). The overall inter-operator coefficient of variation is 6.89%. Conclusions: The technology tested here can facilitate reproducible quantitative morphometry suitable for large studies of vertebral deformities
METHOD OF COMPENSATING LOADS FOR SHALLOW SHELLS. VIBRATION AND STABILITY PROBLEMS
Tran Duc Chinh
2015-01-01
Based on the integral representation of the displacements functions through Green's functions, the author proposed a method to solve the system of differential equations of the given problem. The equations were solved approximately by reducing to algebraic equations by finite difference techniques in Samarsky scheme. Some examples are given for calculation of eigenvalues of shallow shell vibration problem, which are compared with results received by Onyashvili using Galerkin method.
METHOD OF COMPENSATING LOADS FOR SHALLOW SHELLS. VIBRATION AND STABILITY PROBLEMS
Directory of Open Access Journals (Sweden)
Tran Duc Chinh
2015-12-01
Full Text Available Based on the integral representation of the displacements functions through Green's functions, the author proposed a method to solve the system of differential equations of the given problem. The equations were solved approximately by reducing to algebraic equations by finite difference techniques in Samarsky scheme. Some examples are given for calculation of eigenvalues of shallow shell vibration problem, which are compared with results received by Onyashvili using Galerkin method.
a Method for Preview Vibration Control of Systems Having Forcing Inputs and Rapidly-Switched Dampers
ElBeheiry, E. M.
1998-07-01
In a variety of applications, especially in large scale dynamic systems, the mechanization of different vibration control elements in different locations would be decided by limitations placed on the modal vibration of the system and the inherent dynamic coupling between its modes. Also, the quality of vibration control to the economy of producing the whole system would be another trade-off leading to a mix of passive, active and semi-active vibration control elements in one system. This termactiveis limited to externally powered vibration control inputs and the termsemi-activeis limited to rapidly switched dampers. In this article, an optimal preview control method is developed for application to dynamic systems having active and semi-active vibration control elements mechanized at different locations in one system. The system is then a piecewise (bilinear) controller in which two independent sets of control inputs appear additively and multiplicatively. Calculus of variations along with the Hamiltonian approach are employed for the derivation of this method. In essence, it requires the active elements to be ideal force generators and the switched dampers to have the property of on-line variation of the damping characteristics to pre-determined limits. As the dampers switch during operation the whole system's structure differs, and then values of the active forcing inputs are adapted to match these rapid changes. Strictly speaking, each rapidly switched damper has pre-known upper and lower damping levels and it can take on any in-between value. This in-between value is to be determined by the method as long as the damper tracks a pre-known fully active control demand. In every damping state of each semi-active damper the method provides the optimal matching values of the active forcing inputs. The method is shown to have the feature of solving simple standard matrix equations to obtain closed form solutions. A comprehensive 9-DOF tractor semi-trailer model is used
DEFF Research Database (Denmark)
Sørensen, Herman
1997-01-01
Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board......Methods for calculating natural frequencies for ship hulls and for plates and panels.Evaluation of the risk for inconvenient vibrations on board...
Energy Technology Data Exchange (ETDEWEB)
Muto, N. [Hitachi, Ltd., Tokyo (Japan); Kagomiya, K.; Kurosawa, T.; Konya, M>
1998-03-01
Horizontal vibrations of elevator cars mainly occur because a car swings as roller guides installed at corners of a car frame move on a winding guide rail at high speeds. Rider comfort in high speed elevators is worsened by these vibrations. Conventional active dampers suppressing horizontal vibrations using ac servo motors make cars heavier so driving power becomes larger, and they are not easily applied to existing elevators. An active damping control method suited to super-high-speed elevators is which can solve these problems. The method suppresses vibrations by generating only enough magnetic force needed to suppress them only when vibrations of the car franc are produced. The vibrations are detected using acceleration detectors and magnets installed on left and right sides of the car frame. A computer simulator was made to analyze phenomena of car vibrations and to verify effects of the proposed magnetic damping controller. It was found that the vibrations generated on the cabin floor were remarkably large when left and right sides at the upper and lower parts of the car frame were swung by sine waves with the same phase. The vibrations bad two resonant modes. Results obtained with the computer simulator and a full scale running simulator showed that the acceleration on the cabin floor, even at the resonant frequencies, could be reduced by the magnetic damping control to around 0.1m/s{sup 2} which would provide a comfortable ride. 10 refs., 14 figs.
The mechanical spectra of deposited materials by a composite reed vibration method
International Nuclear Information System (INIS)
Ying, X.N.; Zhang, L.; Yuan, Y.H.
2010-01-01
Recently a composite reed vibration method has been designed to measure the mechanical spectra (complex Young's modulus) of materials from liquid to solid state. The mechanical spectra of materials can be obtained from a composite system consisting of a substrate reed and of materials deposited on it. In this report, two sets of formulas to calculate the mechanical spectra of deposited materials are further analyzed. The proof is given for the previous named 'approximate formulas' (labeled as Formula II). Then the composite reed vibration method can be safely used as an extension of the mechanical spectrum method of the thin solid film. At the same time, some comments are made on previous analytical formulas (labeled as Formula I). At last, more experiments with a small amount of deposited materials are performed. It is found that smaller quantity is more favorable to achieve the intrinsic mechanical spectra of deposited materials.
Energy Technology Data Exchange (ETDEWEB)
Unger, E.; Beck, M.; Lipski, R.J.; Dreybrodt, W.; Medforth, C.J.; Smith, K.M.; Schweitzer-Stenner, R.
1999-11-11
The authors have developed a novel method for molecular mechanics calculations and normal-mode analysis. It is based on symmetry of local units that constitutes the given molecule. Compared with general valence force field calculations, the number of free parameters is reduced by 40--80% in the procedure. It was found to reproduce very well the vibrational frequencies and mode compositions of aromatic compounds and porphyrins, as shown by comparison with DFT calculations. A slightly altered force field obtained from Ni(II) porphin was then used to calculate the structure and the normal modes of several meso-substituted Ni(II) porphyrins which are known to be subject to significant ruffling and/or saddling distortions. This method satisfactorily reproduces their nonplanar structure and Raman band frequencies in the natural abundance and isotopic derivative spectra. The polarization properties of bands from out-of-plane modes are in accordance with the predicted nonplanar distortions. Moreover, some of the modes below 800 cm{sup {minus}1} which appear intense in the Raman spectra contain considerable contributions from both in-plane and out-of-plane vibrations, so that the conventional mode assignments become questionable. The authors also demonstrate that the intensity and polarization of some low-frequency Raman bands can be used as a (quantitative) marker to elucidate type and magnitude of out-of-plane distortions. These were recently shown to affect heme groups of hemoglobin, myoglobin, and, in particular, of cytochrome c.
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.
4C-ker: A Method to Reproducibly Identify Genome-Wide Interactions Captured by 4C-Seq Experiments.
Raviram, Ramya; Rocha, Pedro P; Müller, Christian L; Miraldi, Emily R; Badri, Sana; Fu, Yi; Swanzey, Emily; Proudhon, Charlotte; Snetkova, Valentina; Bonneau, Richard; Skok, Jane A
2016-03-01
4C-Seq has proven to be a powerful technique to identify genome-wide interactions with a single locus of interest (or "bait") that can be important for gene regulation. However, analysis of 4C-Seq data is complicated by the many biases inherent to the technique. An important consideration when dealing with 4C-Seq data is the differences in resolution of signal across the genome that result from differences in 3D distance separation from the bait. This leads to the highest signal in the region immediately surrounding the bait and increasingly lower signals in far-cis and trans. Another important aspect of 4C-Seq experiments is the resolution, which is greatly influenced by the choice of restriction enzyme and the frequency at which it can cut the genome. Thus, it is important that a 4C-Seq analysis method is flexible enough to analyze data generated using different enzymes and to identify interactions across the entire genome. Current methods for 4C-Seq analysis only identify interactions in regions near the bait or in regions located in far-cis and trans, but no method comprehensively analyzes 4C signals of different length scales. In addition, some methods also fail in experiments where chromatin fragments are generated using frequent cutter restriction enzymes. Here, we describe 4C-ker, a Hidden-Markov Model based pipeline that identifies regions throughout the genome that interact with the 4C bait locus. In addition, we incorporate methods for the identification of differential interactions in multiple 4C-seq datasets collected from different genotypes or experimental conditions. Adaptive window sizes are used to correct for differences in signal coverage in near-bait regions, far-cis and trans chromosomes. Using several datasets, we demonstrate that 4C-ker outperforms all existing 4C-Seq pipelines in its ability to reproducibly identify interaction domains at all genomic ranges with different resolution enzymes.
Method and device for monitoring vibration of incore neutron detector guide tube
International Nuclear Information System (INIS)
Enomoto, Mitsuhiro; Naito, Norio; Oda, Akira.
1978-01-01
Purpose: To easily detect the vibration of an incore neutron detector guide tube and to prevent the occurrence of such accidents that the guide tube comes into contact with the fuel channel box arranged around the periphery thereof to break the channel box. Method: A neutron detector guide tube is disposed within a channel box, and the neutron detector is arranged at the center of the guide tube. Now, when the guide tube vibrates at an inherent number of vibration and a predetermined amplitude, the guide tube moves in the radial direction by the predetermined amplitude part to come into contact with the channel box. Upon this occasion, the detector similarity vibrates, and the output signal is varied by the predetermined neutron flux variation part. This output signal is sent to a comparator through an analyser, and compared with the output signal produced from a device wherein the result analysed at normal time, and the output signal is sent to an alarm device and an indicator, respectively. (Aizawa, K.)
Vibrational spectroscopic study and NBO analysis on tranexamic acid using DFT method
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.
Investigation of oxygen vibrational relaxation by quasi-classical trajectory method
International Nuclear Information System (INIS)
Andrienko, Daniil; Boyd, Iain D.
2015-01-01
Highlights: • Importance of attraction for the O 2 –O energy exchange in hypersonic flows. • O 2 –O vibrational relaxation time cannot be described by the Millikan–White equation. • Weak dependence of exothermic transition rates on translational temperature. • Multiquantum jumps in molecular oxygen occur mostly via the exchange reaction. - Abstract: O 2 –O collisions are studied by the quasi-classical trajectory method. A full set of cross sections for the vibrational ladder is obtained utilizing an accurate O 3 potential energy surface. Vibrational relaxation is investigated at temperatures between 1000 and 10,000 K, that are relevant to hypersonic flows. The relaxation time is derived based on the removal rate for the first excited vibrational level. A significant deviation from the formula by Millikan and White is observed for temperatures beyond those reported in experimental work. Relaxation becomes less efficient at high temperatures, suggesting that the efficiency of the energy randomization is strongly to the attractive component of the O 3 potential energy surface. These results are explained by analyzing the microscopic parameter of collisions that reflects the number of exchanges in the shortest interatomic distance. The rates of exothermic transitions are found to be nearly independent of the translational temperature in the range of interest.
A Comparison of Vibration and Oil Debris Gear Damage Detection Methods Applied to Pitting Damage
Dempsey, Paula J.
2000-01-01
Helicopter Health Usage Monitoring Systems (HUMS) must provide reliable, real-time performance monitoring of helicopter operating parameters to prevent damage of flight critical components. Helicopter transmission diagnostics are an important part of a helicopter HUMS. In order to improve the reliability of transmission diagnostics, many researchers propose combining two technologies, vibration and oil monitoring, using data fusion and intelligent systems. Some benefits of combining multiple sensors to make decisions include improved detection capabilities and increased probability the event is detected. However, if the sensors are inaccurate, or the features extracted from the sensors are poor predictors of transmission health, integration of these sensors will decrease the accuracy of damage prediction. For this reason, one must verify the individual integrity of vibration and oil analysis methods prior to integrating the two technologies. This research focuses on comparing the capability of two vibration algorithms, FM4 and NA4, and a commercially available on-line oil debris monitor to detect pitting damage on spur gears in the NASA Glenn Research Center Spur Gear Fatigue Test Rig. Results from this research indicate that the rate of change of debris mass measured by the oil debris monitor is comparable to the vibration algorithms in detecting gear pitting damage.
Errors in the estimation method for the rejection of vibrations in adaptive optics systems
Kania, Dariusz
2017-06-01
In recent years the problem of the mechanical vibrations impact in adaptive optics (AO) systems has been renewed. These signals are damped sinusoidal signals and have deleterious effect on the system. One of software solutions to reject the vibrations is an adaptive method called AVC (Adaptive Vibration Cancellation) where the procedure has three steps: estimation of perturbation parameters, estimation of the frequency response of the plant, update the reference signal to reject/minimalize the vibration. In the first step a very important problem is the estimation method. A very accurate and fast (below 10 ms) estimation method of these three parameters has been presented in several publications in recent years. The method is based on using the spectrum interpolation and MSD time windows and it can be used to estimate multifrequency signals. In this paper the estimation method is used in the AVC method to increase the system performance. There are several parameters that affect the accuracy of obtained results, e.g. CiR - number of signal periods in a measurement window, N - number of samples in the FFT procedure, H - time window order, SNR, b - number of ADC bits, γ - damping ratio of the tested signal. Systematic errors increase when N, CiR, H decrease and when γ increases. The value for systematic error is approximately 10^-10 Hz/Hz for N = 2048 and CiR = 0.1. This paper presents equations that can used to estimate maximum systematic errors for given values of H, CiR and N before the start of the estimation process.
Removing damped sinusoidal vibrations in adaptive optics systems using a DFT-based estimation method
Kania, Dariusz
2017-06-01
The problem of a vibrations rejection in adaptive optics systems is still present in publications. These undesirable signals emerge because of shaking the system structure, the tracking process, etc., and they usually are damped sinusoidal signals. There are some mechanical solutions to reduce the signals but they are not very effective. One of software solutions are very popular adaptive methods. An AVC (Adaptive Vibration Cancellation) method has been presented and developed in recent years. The method is based on the estimation of three vibrations parameters and values of frequency, amplitude and phase are essential to produce and adjust a proper signal to reduce or eliminate vibrations signals. This paper presents a fast (below 10 ms) and accurate estimation method of frequency, amplitude and phase of a multifrequency signal that can be used in the AVC method to increase the AO system performance. The method accuracy depends on several parameters: CiR - number of signal periods in a measurement window, N - number of samples in the FFT procedure, H - time window order, SNR, THD, b - number of A/D converter bits in a real time system, γ - the damping ratio of the tested signal, φ - the phase of the tested signal. Systematic errors increase when N, CiR, H decrease and when γ increases. The value of systematic error for γ = 0.1%, CiR = 1.1 and N = 32 is approximately 10^-4 Hz/Hz. This paper focuses on systematic errors of and effect of the signal phase and values of γ on the results.
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.
Directory of Open Access Journals (Sweden)
Elham Ghandi
2016-09-01
Full Text Available The free vibration of frame structures has been usually studied in literature without considering the effect of axial loads. In this paper, the continuous system method is employed to investigate this effect on the free flexural and torsional vibration of two and three dimensional symmetric frames. In the continuous system method, in approximate analysis of buildings, commonly, the structure is replaced by an equivalent beam which matches the dominant characteristics of the structure. Accordingly, the natural frequencies of the symmetric frame structures are obtained through solving the governing differential equation of the equivalent beam whose stiffness and mass are supposed to be uniformly distributed along the length. The corresponding axial load applied to the replaced beam is calculated based on the total weight and the number of stories of the building. A numerical example is presented to show the simplicity and efficiency of the proposed solution.
Homotopy perturbation method for free vibration analysis of beams on elastic foundation
International Nuclear Information System (INIS)
Ozturk, Baki; Coskun, Safa Bozkurt; Koc, Mehmet Zahid; Atay, Mehmet Tarik
2010-01-01
In this study, the homotopy perturbation method (HPM) is applied for free vibration analysis of beam on elastic foundation. This numerical method is applied on a previously available case study. Analytical solutions and frequency factors are evaluated for different ratios of axial load N acting on the beam to Euler buckling load, N r . The application of HPM for the particular problem in this study gives results which are in excellent agreement with both analytical solutions and the variational iteration method (VIM) solutions for the case considered in this study and the differential transform method (DTM) results available in the literature.
Research on a new type of precision cropping method with variable frequency vibration
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
Aiming at the cropping operations widely applied in practical industry production, a new method of bar cropping is presented. The rotational speeds of actuating motor of eccentric blocks are controlled by a frequency-changer, and the shearing die provides the bar with the controllable force, frequency and amplitude of vibration. By utilizing the stress concentration at the bottom of V shape groove on the bar, the low stress bar cropping is realized. The bar cropping experiments of duralumin alloy and steel ...
Active vibration control using state space LQG and internal model control methods
DEFF Research Database (Denmark)
Mørkholt, Jakob; Elliott, S.J.
1998-01-01
Two ways of designing discrete time robust H2-controllers for feedback broadband active vibration control are compared through computer simulations. The methods are based on different models of disturbance and plant transfer functions, but yield controllers with identical properties. Two simple...... ways of introducing robustness into the H2-design are compared, and finally an efficient way of designing a practical IIR-controller is proposed....
Directory of Open Access Journals (Sweden)
H. А. Vershina
2012-01-01
Full Text Available The paper presents investigations of processes pertaining to surface charge accumulation and running of fluoropolymer-4 products using vibrating capacitor method. Modification of a measurement technique allowing to register distribution of dielectric surface potential without disturbance of the surface charged state has been described in the paper. The paper contains graphics of spatial distribution of surface potential of fluoropolymer-4 products after various treatments. The paper reveals that thermal treatment (tempering reduces static characteristics of fluoropolymer-4.
Directory of Open Access Journals (Sweden)
A.M. Yu
2012-01-01
Full Text Available Free vibration equations for non-cylindrical (conical, barrel, and hyperboloidal types helical springs with noncircular cross-sections, which consist of 14 first-order ordinary differential equations with variable coefficients, are theoretically derived using spatially curved beam theory. In the formulation, the warping effect upon natural frequencies and vibrating mode shapes is first studied in addition to including the rotary inertia, the shear and axial deformation influences. The natural frequencies of the springs are determined by the use of improved Riccati transfer matrix method. The element transfer matrix used in the solution is calculated using the Scaling and Squaring method and Pad'e approximations. Three examples are presented for three types of springs with different cross-sectional shapes under clamped-clamped boundary condition. The accuracy of the proposed method has been compared with the FEM results using three-dimensional solid elements (Solid 45 in ANSYS code. Numerical results reveal that the warping effect is more pronounced in the case of non-cylindrical helical springs than that of cylindrical helical springs, which should be taken into consideration in the free vibration analysis of such springs.
A-VCI: A flexible method to efficiently compute vibrational spectra
Odunlami, Marc; Le Bris, Vincent; Bégué, Didier; Baraille, Isabelle; Coulaud, Olivier
2017-06-01
The adaptive vibrational configuration interaction algorithm has been introduced as a new method to efficiently reduce the dimension of the set of basis functions used in a vibrational configuration interaction process. It is based on the construction of nested bases for the discretization of the Hamiltonian operator according to a theoretical criterion that ensures the convergence of the method. In the present work, the Hamiltonian is written as a sum of products of operators. The purpose of this paper is to study the properties and outline the performance details of the main steps of the algorithm. New parameters have been incorporated to increase flexibility, and their influence has been thoroughly investigated. The robustness and reliability of the method are demonstrated for the computation of the vibrational spectrum up to 3000 cm-1 of a widely studied 6-atom molecule (acetonitrile). Our results are compared to the most accurate up to date computation; we also give a new reference calculation for future work on this system. The algorithm has also been applied to a more challenging 7-atom molecule (ethylene oxide). The computed spectrum up to 3200 cm-1 is the most accurate computation that exists today on such systems.
Mechanical vibration compensation method for 3D+t multi-particle tracking in microscopic volumes.
Pimentel, A; Corkidi, G
2009-01-01
The acquisition and analysis of data in microscopic systems with spatiotemporal evolution is a very relevant topic. In this work, we describe a method to optimize an experimental setup for acquiring and processing spatiotemporal (3D+t) data in microscopic systems. The method is applied to a three-dimensional multi-tracking and analysis system of free-swimming sperm trajectories previously developed. The experimental set uses a piezoelectric device making oscillate a large focal-distance objective mounted on an inverted microscope (over its optical axis) to acquire stacks of images at a high frame rate over a depth on the order of 250 microns. A problem arise when the piezoelectric device oscillates, in such a way that a vibration is transmitted to the whole microscope, inducing undesirable 3D vibrations to the whole set. For this reason, as a first step, the biological preparation was isolated from the body of the microscope to avoid modifying the free swimming pattern of the microorganism due to the transmission of these vibrations. Nevertheless, as the image capturing device is mechanically attached to the "vibrating" microscope, the resulting acquired data are contaminated with an undesirable 3D movement that biases the original trajectory of these high speed moving cells. The proposed optimization method determines the functional form of these 3D oscillations to neutralize them from the original acquired data set. Given the spatial scale of the system, the added correction increases significantly the data accuracy. The optimized system may be very useful in a wide variety of 3D+t applications using moving optical devices.
Fiducialization of the small-aperture quadrupoles based on the vibrating wire method
Energy Technology Data Exchange (ETDEWEB)
Wang, Baichuan, E-mail: wangbaichuan@nint.ac.cn [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect (Northwest Institute of Nuclear Technology), Xi' an 710024 (China); Tsinghua University, Beijing 100084 (China); Zheng, Shuxin, E-mail: zhengsx@tsinghua.edu.cn [Tsinghua University, Beijing 100084 (China); Wu, Lin; Du, Changtong; Xing, Qingzi [Tsinghua University, Beijing 100084 (China); Wang, Zhongming; Qiu, Mengtong [State Key Laboratory of Intense Pulsed Radiation Simulation and Effect (Northwest Institute of Nuclear Technology), Xi' an 710024 (China); Wang, Xuewu [Tsinghua University, Beijing 100084 (China)
2016-03-11
A fiducialization method based on vibrating wire is described dedicated to the problem of locating the magnetic center relative to external fiducials for the small-aperture quadrupoles. The advantage of this method is that the measurement of the wire position, which may be the main error source, is no longer needed. The position of the magnetic center can be directly obtained by measuring the position shift of the magnet fiducials. This method has been validated on small Permanent Magnet Quadrupoles (PMQs). Experiments have confirmed its feasibility of measuring PMQs with good repeatability of about 10 μm, and shown its high sensitivity as well as convenience.
4C-ker: A Method to Reproducibly Identify Genome-Wide Interactions Captured by 4C-Seq Experiments.
Directory of Open Access Journals (Sweden)
Ramya Raviram
2016-03-01
Full Text Available 4C-Seq has proven to be a powerful technique to identify genome-wide interactions with a single locus of interest (or "bait" that can be important for gene regulation. However, analysis of 4C-Seq data is complicated by the many biases inherent to the technique. An important consideration when dealing with 4C-Seq data is the differences in resolution of signal across the genome that result from differences in 3D distance separation from the bait. This leads to the highest signal in the region immediately surrounding the bait and increasingly lower signals in far-cis and trans. Another important aspect of 4C-Seq experiments is the resolution, which is greatly influenced by the choice of restriction enzyme and the frequency at which it can cut the genome. Thus, it is important that a 4C-Seq analysis method is flexible enough to analyze data generated using different enzymes and to identify interactions across the entire genome. Current methods for 4C-Seq analysis only identify interactions in regions near the bait or in regions located in far-cis and trans, but no method comprehensively analyzes 4C signals of different length scales. In addition, some methods also fail in experiments where chromatin fragments are generated using frequent cutter restriction enzymes. Here, we describe 4C-ker, a Hidden-Markov Model based pipeline that identifies regions throughout the genome that interact with the 4C bait locus. In addition, we incorporate methods for the identification of differential interactions in multiple 4C-seq datasets collected from different genotypes or experimental conditions. Adaptive window sizes are used to correct for differences in signal coverage in near-bait regions, far-cis and trans chromosomes. Using several datasets, we demonstrate that 4C-ker outperforms all existing 4C-Seq pipelines in its ability to reproducibly identify interaction domains at all genomic ranges with different resolution enzymes.
International Nuclear Information System (INIS)
Gunyasu, Kenzo; Hiramoto, Tsuneyuki; Tanimoto, Mitsumori; Osano, Minetada
2002-01-01
We describe a new method for solving large-scale system of linear equations resulting from discretization of ordinary differential equation and partial differential equation directly. This new method effectively reduces the memory capacity requirements and computing time problems for analyses using finite difference method and finite element method. In this paper we have tried to solve one-million linear equations directly for the case that initial displacement and boundary displacement are known about the finite difference scheme of second order inhomogeneous differential equation for vibration of a 10 story structure. Excellent results were got. (author)
Wang, H. P.; Guan, Y. C.; Zheng, H. Y.
2017-12-01
Rough surface features induced by laser irradiation have been a challenging for the fabrication of micro/nano scale features. In this work, we propose hybrid ultrasonic vibration polishing method to improve surface quality of microcraters produced by femtosecond laser irradiation on cemented carbide. The laser caused rough surfaces are significantly smoothened after ultrasonic vibration polishing due to the strong collision effect of diamond particles on the surfaces. 3D morphology, SEM and AFM analysis has been conducted to characterize surface morphology and topography. Results indicate that the minimal surface roughness of Ra 7.60 nm has been achieved on the polished surfaces. The fabrication of microcraters with smooth surfaces is applicable to molding process for mass production of micro-optical components.
The GDQ Method of Thermal Vibration Laminated Shell with Actuating Magnetostrictive Layers
Directory of Open Access Journals (Sweden)
C.C. Hong
2017-06-01
Full Text Available The research of laminated magnetostrictive shell under thermal vibration was computed by using the generalized differential quadrature (GDQ method. In the thermoelastic stress-strain equations that contain the terms linear temperature rise and the magnetostrictive material with velocity feedback control. The dynamic equilibrium differential equations with displacements were normalized and discretized into the dynamic discretized equations by the GDQ method. Two edges of laminated shell with clamped boundary conditions were considered. The values of interlaminar thermal stresses and center displacement of shell with and without velocity feedback control were calculated, respectively. The purpose of this research is to compute the time responses of displacement and stresses in the laminated magnetostrictive shell subjected to thermal vibration with suitable controlled gain values. The numerical GDQ results of displacement and stresses are also obtained and investigated. With velocity feedback and suitable control gain values are found to reduce the amplitude of displacement and stresses into a smaller value. The higher values of temperature get the higher amplitude of displacement and stresses. The GDQ results of actuating magnetostrictive shells can be applied in the field of morphing aircraft (adaptive structures and smart materials to reduce and suppress the vibration when under aero-thermal flutter.
Free vibration analysis of multi-span pipe conveying fluid with dynamic stiffness method
International Nuclear Information System (INIS)
Li Baohui; Gao Hangshan; Zhai Hongbo; Liu Yongshou; Yue Zhufeng
2011-01-01
Research highlights: → The dynamic stiffness method was proposed to analysis the free vibration of multi-span pipe conveying fluid. → The main advantage of the proposed method is that it can hold a high precision even though the element size is large. → The flowing fluid can weaken the pipe stiffness, when the fluid velocity increases, the natural frequencies of pipe are decreasing. - Abstract: By taking a pipe as Timoshenko beam, in this paper the original 4-equation model of pipe conveying fluid was modified by taking the dynamic effects of fluid into account. The shape function that always used in the finite element method was replaced by the exact wave solution of the modified four equations. And then the dynamic stiffness was deduced for the free vibration of pipe conveying fluid. The proposed method was validated by comparing the results of critical velocity with analytical solution for a simply supported pipe at both ends. In the example, the proposed method was applied to calculate the first three natural frequencies of a three span pipe with twelve meters long in three different cases. The results of natural frequency for the pipe conveying stationary fluid fitted well with that calculated by finite element software Abaqus. It was shown that the dynamic stiffness method can still hold high precision even though the element's size was quite large. And this is the predominant advantage of the proposed method comparing with conventional finite element method.
An Accurate Integral Method for Vibration Signal Based on Feature Information Extraction
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Yong Zhu
2015-01-01
Full Text Available After summarizing the advantages and disadvantages of current integral methods, a novel vibration signal integral method based on feature information extraction was proposed. This method took full advantage of the self-adaptive filter characteristic and waveform correction feature of ensemble empirical mode decomposition in dealing with nonlinear and nonstationary signals. This research merged the superiorities of kurtosis, mean square error, energy, and singular value decomposition on signal feature extraction. The values of the four indexes aforementioned were combined into a feature vector. Then, the connotative characteristic components in vibration signal were accurately extracted by Euclidean distance search, and the desired integral signals were precisely reconstructed. With this method, the interference problem of invalid signal such as trend item and noise which plague traditional methods is commendably solved. The great cumulative error from the traditional time-domain integral is effectively overcome. Moreover, the large low-frequency error from the traditional frequency-domain integral is successfully avoided. Comparing with the traditional integral methods, this method is outstanding at removing noise and retaining useful feature information and shows higher accuracy and superiority.
DEFF Research Database (Denmark)
Pomogaev, Vladimir; Pomogaeva, Anna; Avramov, Pavel
2011-01-01
Three polycyclic organic molecules in various solvents focused on thermo-dynamical aspects were theoretically investigated using the recently developed statistical quantum mechanical/classical molecular dynamics method for simulating electronic-vibrational spectra. The absorption bands of estradiol...
Theory of vibration protection
Karnovsky, Igor A
2016-01-01
This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...
Free vibration of functionally graded beams and frameworks using the dynamic stiffness method
Banerjee, J. R.; Ananthapuvirajah, A.
2018-05-01
The free vibration analysis of functionally graded beams (FGBs) and frameworks containing FGBs is carried out by applying the dynamic stiffness method and deriving the elements of the dynamic stiffness matrix in explicit algebraic form. The usually adopted rule that the material properties of the FGB vary continuously through the thickness according to a power law forms the fundamental basis of the governing differential equations of motion in free vibration. The differential equations are solved in closed analytical form when the free vibratory motion is harmonic. The dynamic stiffness matrix is then formulated by relating the amplitudes of forces to those of the displacements at the two ends of the beam. Next, the explicit algebraic expressions for the dynamic stiffness elements are derived with the help of symbolic computation. Finally the Wittrick-Williams algorithm is applied as solution technique to solve the free vibration problems of FGBs with uniform cross-section, stepped FGBs and frameworks consisting of FGBs. Some numerical results are validated against published results, but in the absence of published results for frameworks containing FGBs, consistency checks on the reliability of results are performed. The paper closes with discussion of results and conclusions.
Comparison of force fields and calculation methods for vibration intervals of isotopic H+3 molecules
International Nuclear Information System (INIS)
Carney, G.D.; Adler-Golden, S.M.; Lesseski, D.C.
1986-01-01
This paper reports (a) improved values for low-lying vibration intervals of H + 3 , H 2 D + , D 2 H + , and D + 3 calculated using the variational method and Simons--Parr--Finlan representations of the Carney--Porter and Dykstra--Swope ab initio H + 3 potential energy surfaces, (b) quartic normal coordinate force fields for isotopic H + 3 molecules, (c) comparisons of variational and second-order perturbation theory, and (d) convergence properties of the Lai--Hagstrom internal coordinate vibrational Hamiltonian. Standard deviations between experimental and ab initio fundamental vibration intervals of H + 3 , H 2 D + , D 2 H + , and D + 3 for these potential surfaces are 6.9 (Carney--Porter) and 1.2 cm -1 (Dykstra--Swope). The standard deviations between perturbation theory and exact variational fundamentals are 5 and 10 cm -1 for the respective surfaces. The internal coordinate Hamiltonian is found to be less efficient than the previously employed ''t'' coordinate Hamiltonian for these molecules, except in the case of H 2 D +
A synergistic method for vibration suppression of an elevator mechatronic system
Knezevic, Bojan Z.; Blanusa, Branko; Marcetic, Darko P.
2017-10-01
Modern elevators are complex mechatronic systems which have to satisfy high performance in precision, safety and ride comfort. Each elevator mechatronic system (EMS) contains a mechanical subsystem which is characterized by its resonant frequency. In order to achieve high performance of the whole system, the control part of the EMS inevitably excites resonant circuits causing the occurrence of vibration. This paper proposes a synergistic solution based on the jerk control and the upgrade of the speed controller with a band-stop filter to restore lost ride comfort and speed control caused by vibration. The band-stop filter eliminates the resonant component from the speed controller spectra and jerk control provides operating of the speed controller in a linear mode as well as increased ride comfort. The original method for band-stop filter tuning based on Goertzel algorithm and Kiefer search algorithm is proposed in this paper. In order to generate the speed reference trajectory which can be defined by different shapes and amplitudes of jerk, a unique generalized model is proposed. The proposed algorithm is integrated in the power drive control algorithm and implemented on the digital signal processor. Through experimental verifications on a scale down prototype of the EMS it has been verified that only synergistic effect of controlling jerk and filtrating the reference torque can completely eliminate vibrations.
Directory of Open Access Journals (Sweden)
Maziar Janghorban
Full Text Available Static and free vibration analysis of carbon nano wires with rectangular cross section based on Timoshenko beam theory is studied in this research. Differential quadrature method (DQM is employed to solve the governing equations. From the knowledge of author, it is the first time that free vibration of nano wires is investigated. It is also the first time that differential quadrature method is used for bending analysis of nano wires.
Investigation on method of estimating the excitation spectrum of vibration source
International Nuclear Information System (INIS)
Zhang Kun; Sun Lei; Lin Song
2010-01-01
In practical engineer area, it is hard to obtain the excitation spectrum of the auxiliary machines of nuclear reactor through direct measurement. To solve this problem, the general method of estimating the excitation spectrum of vibration source through indirect measurement is proposed. First, the dynamic transfer matrix between the virtual excitation points and the measure points is obtained through experiment. The matrix combined with the response spectrum at the measure points under practical work condition can be used to calculate the excitation spectrum acts on the virtual excitation points. Then a simplified method is proposed which is based on the assumption that the vibration machine can be regarded as rigid body. The method treats the centroid as the excitation point and the dynamic transfer matrix is derived by using the sub structure mobility synthesis method. Thus, the excitation spectrum can be obtained by the inverse of the transfer matrix combined with the response spectrum at the measure points. Based on the above method, a computing example is carried out to estimate the excitation spectrum acts on the centroid of a electrical pump. By comparing the input excitation and the estimated excitation, the reliability of this method is verified. (authors)
Modified multiple time scale method for solving strongly nonlinear damped forced vibration systems
Razzak, M. A.; Alam, M. Z.; Sharif, M. N.
2018-03-01
In this paper, modified multiple time scale (MTS) method is employed to solve strongly nonlinear forced vibration systems. The first-order approximation is only considered in order to avoid complexicity. The formulations and the determination of the solution procedure are very easy and straightforward. The classical multiple time scale (MS) and multiple scales Lindstedt-Poincare method (MSLP) do not give desire result for the strongly damped forced vibration systems with strong damping effects. The main aim of this paper is to remove these limitations. Two examples are considered to illustrate the effectiveness and convenience of the present procedure. The approximate external frequencies and the corresponding approximate solutions are determined by the present method. The results give good coincidence with corresponding numerical solution (considered to be exact) and also provide better result than other existing results. For weak nonlinearities with weak damping effect, the absolute relative error measures (first-order approximate external frequency) in this paper is only 0.07% when amplitude A = 1.5 , while the relative error gives MSLP method is surprisingly 28.81%. Furthermore, for strong nonlinearities with strong damping effect, the absolute relative error found in this article is only 0.02%, whereas the relative error obtained by MSLP method is 24.18%. Therefore, the present method is not only valid for weakly nonlinear damped forced systems, but also gives better result for strongly nonlinear systems with both small and strong damping effect.
Life Cycle Cost Evaluation of Noise and Vibration Control Methods at Urban Railway Turnouts
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Rodrigo Tavares de Freitas
2016-12-01
Full Text Available A focus of the railway industry over the past decades has been to research, find and develop methods to mitigate noise and vibration resulting from wheel/rail contact along track infrastructure. This resulted in a wide range of abatement measures that are available for today’s engineers. The suitability of each method must be analysed through budget and timeframe limitations, which includes building, maintenance and inspection costs and time allocation, while also aiming at delivering other benefits, such as environmental impact and durability of infrastructure. There are several situations that need noise and vibration mitigation methods, but each design allocates different priorities on a case-by-case basis. Traditionally, the disturbance caused by railways to the community are generated by wheel/rail contact sound radiation that is expressed in different ways, depending on the movement of the rolling stock and track alignment, such as rolling noise, impact noise and curve noise. More specifically, in special trackworks such as turnouts (or called “switches and crossings”, there are two types of noise that can often be observed: impact noise and screeching noise. With respect to the screeching (or flanging, its mitigation methods are usually associated with curve lubrications. In contrast, the impact noise emerges from the sound made by the rolling stock moving through joints and discontinuities (i.e., gaps, resulting in various noise abatement features to minimise such noise impact. Life cycle analysis is therefore vital for cost efficiency benchmarking of the mitigation methods. The evaluation is based on available data from open literature and the total costs were estimated from valid industry reports to maintain coherency. A 50-year period for a life cycle analysis is chosen for this study. As for the general parameters, an area with a high density of people is considered to estimate the values for a community with very strict limits
Method for qualification of cementation processes and its application to a vibration mixer
International Nuclear Information System (INIS)
Vicente, R.; Rzyski, B.M.; Suarez, A.A.
1987-01-01
In this paper the definition of homogeneneity is discussed and methods to measure the 'degree of heterogeneity' of waste forms are proposed. These measurements are important as aids for mixing process qualification, and as tools in quality assurance procedures and in the development of waste management standards. Homogeneity is a basic quality requirement for waste forms to be accepted in final sites. It do not depend on the matrix immmobilization, rather it is one mean for qualification of the immobilization process. The proposed methods were applied to a vibration assisted mixing process and has proved to an useful mean to judge process improvements. There are many conceivable methods to evaluate homogeneity of waste forms. Some were selected as screening tests aiming at quickly reaching a promising set of process variables. Others were selected to evaluate the degree of excellence of the process in respect to product quality. These envisaged methods were: visual inspection, the use of cement dye as tracer, scanning of radioactive tracers, and measurements of variations of density, water absorption, porosity and mechanical strength across the waste form sample. The process variables were: waste-cement and water-cement ratios, mixer geometry, mixing time and vibration intensity. Some of the apparatus details were change during the experimental work in order to improve product quality. Experimental methods and results statistically analysed and compared with data obtained from samples prepared with a planetary paddle mixer, which were adopted as the homogeneity standard. (Author) [pt
Numerical calculation of acoustic radiation from band-vibrating structures via FEM/FAQP method
Directory of Open Access Journals (Sweden)
GAO Honglin
2017-08-01
Full Text Available The Finite Element Method (FEM combined with the Frequency Averaged Quadratic Pressure method (FAQP are used to calculate the acoustic radiation of structures excited in the frequency band. The surface particle velocity of stiffened cylindrical shells under frequency band excitation is calculated using finite element software, the normal vibration velocity is converted from the surface particle velocity to calculate the average energy source (frequency averaged across intensity, frequency averaged across pressure and frequency averaged across velocity, and the FAQP method is used to calculate the average sound pressure level within the bandwidth. The average sound pressure levels are then compared with the bandwidth using finite element and boundary element software, and the results show that FEM combined with FAQP is more suitable for high frequencies and can be used to calculate the average sound pressure level in the 1/3 octave band with good stability, presenting an alternative to applying frequency-by-frequency calculation and the average frequency process. The FEM/FAQP method can be used as a prediction method for calculating acoustic radiation while taking the randomness of vibration at medium and high frequencies into consideration.
Parameter optimization method for longitudinal vibration absorber of ship shaft system
Directory of Open Access Journals (Sweden)
LIU Jinlin
2017-05-01
Full Text Available The longitudinal vibration of the ship shaft system is the one of the most important factors of hull stern vibration, and it can be effectively minimized by installing a longitudinal vibration absorber. In this way, the vibration and noise of ships can be brought under control. However, the parameters of longitudinal vibration absorbers have a great influence on the vibration characteristics of the shaft system. As such, a certain shafting testing platform was studied as the object on which a finite model was built, and the relationship between longitudinal stiffness and longitudinal vibration in the shaft system was analyzed in a straight alignment state. Furthermore, a longitudinal damping model of the shaft system was built in which the parameters of the vibration absorber were non-dimensionalized, the weight of the vibration absorber was set as a constant, and an optimizing algorithm was used to calculate the optimized stiffness and damping coefficient of the vibration absorber. Finally, the longitudinal vibration frequency response of the shafting testing platform before and after optimizing the parameters of the longitudinal vibration absorber were compared, and the results indicated that the longitudinal vibration of the shafting testing platform was decreased effectively, which suggests that it could provide a theoretical foundation for the parameter optimization of longitudinal vibration absorbers.
A simplified method for random vibration analysis of structures with random parameters
International Nuclear Information System (INIS)
Ghienne, Martin; Blanzé, Claude
2016-01-01
Piezoelectric patches with adapted electrical circuits or viscoelastic dissipative materials are two solutions particularly adapted to reduce vibration of light structures. To accurately design these solutions, it is necessary to describe precisely the dynamical behaviour of the structure. It may quickly become computationally intensive to describe robustly this behaviour for a structure with nonlinear phenomena, such as contact or friction for bolted structures, and uncertain variations of its parameters. The aim of this work is to propose a non-intrusive reduced stochastic method to characterize robustly the vibrational response of a structure with random parameters. Our goal is to characterize the eigenspace of linear systems with dynamic properties considered as random variables. This method is based on a separation of random aspects from deterministic aspects and allows us to estimate the first central moments of each random eigenfrequency with a single deterministic finite elements computation. The method is applied to a frame with several Young's moduli modeled as random variables. This example could be expanded to a bolted structure including piezoelectric devices. The method needs to be enhanced when random eigenvalues are closely spaced. An indicator with no additional computational cost is proposed to characterize the ’’proximity” of two random eigenvalues. (paper)
Use of the finite element displacement method to solve solid-fluid interaction vibration problems
International Nuclear Information System (INIS)
Brown, S.J.; Hsu, K.H.
1978-01-01
It is shown through comparison to experimental, theoretical, and other finite element formulations that the finite element displacement method can solve accurately and economically a certain class of solid-fluid eigenvalue problems. The problems considered are small displacements in the absence of viscous damping and are 2-D and 3-D in nature. In this study the advantages of the finite element method (in particular the displacement formulation) is apparent in that a large structure consisting of the cylinders, support flanges, fluid, and other experimental boundaries could be modeled to yield good correlation to experimental data. The ability to handle large problems with standard structural programs is the key advantage of the displacement fluid method. The greatest obstacle is the inability of the analyst to inhibit those rotational degrees of freedom that are unnecessary to his fluid-structure vibration problem. With judicious use of element formulation, boundary conditions and modeling, the displacement finite element method can be successfully used to predict solid-fluid response to vibration and seismic loading
Directory of Open Access Journals (Sweden)
Johan Debayle
2011-05-01
Full Text Available An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.
Directory of Open Access Journals (Sweden)
Angelo Fabbri
2017-06-01
Full Text Available Walk behind tractors have some advantages over other agricultural machines, such as the cheapness and the easy to use, however the driver is exposed to high level of vibrations transmitted from handles to hand-arm system and to shoulders. The vibrations induce discomfort and early fatigue to the operator. In order to control the vibration transmissibility, a ballast mass may be added to the handles. Even if the determination of the appropriate ballast mass is a critical point in the handle design. The aim of this research was to study the influence of the handle mass modification, on the dynamic structure behaviour. Modal frequencies and subsequent transmissibility calculated by using an analytical approach and a finite elements model, were compared. A good agreement between the results obtained by the two methods was found (average percentage difference calculated on natural frequencies equal to 5.8±3.8%. Power tillers are made generally by small or medium-small size manufacturers that have difficulties in dealing with finite element codes or modal analysis techniques. As a consequence, the proposed analytical method could be used to find the optimal ballast mass in a simple and economic way, without experimental tests or complex finite element codes. A specific and very simple software or spreadsheet, developed on the base of the analytical method here discussed, could effectively to help the manufacturers in the handlebar design phase. The choice of the correct elastic mount, the dimensioning of the guide members and the ballast mass could be considerably simplified.
Apparatus and method of inserting a microelectrode in body tissue or the like using vibration means
Feldstein, C.; Crawford, D. W.; Kanabus, E. W. (Inventor)
1979-01-01
An arrangement for and method of inserting a glass microelectrode having a tip in the micron range into body tissue is presented. The arrangement includes a microelectrode. The top of the microelectrode is attached to the diaphragm center of a first speaker. The microelectrode tip is brought into contact with the tissue by controlling a micromanipulator. Thereafter, an audio signal is applied to the speaker to cause the microelectrode to vibrate and thereby pierce the tissue surface without breaking the microelectrode tip. Thereafter, the tip is inserted into the tissue to the desired depth by operating the micromanipulator with the microelectrode in a vibratory or non-vibratory state.
Conformational analysis and vibrational studies of ethylenediamine-d4, using DFT method
International Nuclear Information System (INIS)
Catikkas, B.
2010-01-01
In this work, conformational analysis and quantum chemical calculations of ethylenediamine-d4 were carried out. The geometry optimization and the geometric parameters (bond length, bond angle and tortion angle) were calculated. The Infrared and Raman frequencies of fundamental modes of the most stable conformer were determined. Calculations were carried out by using the MPW1PW91/6-311+G(d,p) method and Gaussian03 and GaussView3.0 programs. Populations of the conformers was calculated. Vibrational assignments of the title molecule were calculated by using Scaled Quantum Mechanical (SQM) analysis. Calculated values were compared with the experimental ones.
Analysis of factors influencing fire damage to concrete using nonlinear resonance vibration method
Energy Technology Data Exchange (ETDEWEB)
Park, Gang Kyu; Park, Sun Jong; Kwak, Hyo Gyoung [Civil and Environmental Engineering, Korea Advanced Institute of Science and Technology, KAIST, Daejeon (Korea, Republic of); Yim, Hong Jae [Dept. of Construction and Disaster Prevention Engineering, Kyungpook National University, Sangju (Korea, Republic of)
2015-04-15
In this study, the effects of different mix proportions and fire scenarios (exposure temperatures and post-fire-curing periods) on fire-damaged concrete were analyzed using a nonlinear resonance vibration method based on nonlinear acoustics. The hysteretic nonlinearity parameter was obtained, which can sensitively reflect the damage level of fire-damaged concrete. In addition, a splitting tensile strength test was performed on each fire-damaged specimen to evaluate the residual property. Using the results, a prediction model for estimating the residual strength of fire-damaged concrete was proposed on the basis of the correlation between the hysteretic nonlinearity parameter and the ratio of splitting tensile strength.
Mulder, E.R.; de Jong, R.A.; Knol, D.L.; van Schijndel, R.A.; Cover, K.S.; Visser, P.J.; Barkhof, F.; Vrenken, H.
2014-01-01
Background: To measure hippocampal volume change in Alzheimer's disease (AD) or mild cognitive impairment (MCI), expert manual delineation is often used because of its supposed accuracy. It has been suggested that expert outlining yields poorer reproducibility as compared to automated methods, but
Free Vibration Analysis for Shells of Revolution Using an Exact Dynamic Stiffness Method
Directory of Open Access Journals (Sweden)
Xudong Chen
2016-01-01
Full Text Available An exact generalised formulation for the free vibration of shells of revolution with general shaped meridians and arbitrary boundary conditions is introduced. Starting from the basic shell theories, the vibration governing equations are obtained in the Hamilton form, from which dynamic stiffness is computed using the ordinary differential equations solver COLSYS. Natural frequencies and modes are determined by employing the Wittrick-Williams (W-W algorithm in conjunction with the recursive Newton’s method, thus expanding the applications of the abovementioned techniques from one-dimensional skeletal structures to two-dimensional shells of revolution. A solution for solving the number of clamped-end frequencies J0 in the W-W algorithm is presented for both uniform and nonuniform shell segment members. Based on these theories, a FORTRAN program is written. Numerical examples on circular cylindrical shells, hyperboloidal cooling tower shells, and spherical shells are given, and error analysis is performed. The convergence of the proposed method on J0 is verified, and comparisons with frequencies from existing literature show that the dynamic stiffness method is robust, reliable, and accurate.
Directory of Open Access Journals (Sweden)
Yi Cao
2013-06-01
Full Text Available A novel intelligent fault diagnosis method for motor roller bearings which operate under unsteady rotating speed and load is proposed in this paper. The pseudo Wigner-Ville distribution (PWVD and the relative crossing information (RCI methods are used for extracting the feature spectra from the non-stationary vibration signal measured for condition diagnosis. The RCI is used to automatically extract the feature spectrum from the time-frequency distribution of the vibration signal. The extracted feature spectrum is instantaneous, and not correlated with the rotation speed and load. By using the ant colony optimization (ACO clustering algorithm, the synthesizing symptom parameters (SSP for condition diagnosis are obtained. The experimental results shows that the diagnostic sensitivity of the SSP is higher than original symptom parameter (SP, and the SSP can sensitively reflect the characteristics of the feature spectrum for precise condition diagnosis. Finally, a fuzzy diagnosis method based on sequential inference and possibility theory is also proposed, by which the conditions of the machine can be identified sequentially as well.
International Nuclear Information System (INIS)
Nambu, Yohsuke; Takashima, Toshihide; Inagaki, Akiya
2015-01-01
This paper examines the effects of connecting multiplexing shunt circuits composed of inductors and resistors to piezoelectric transducers so as to improve the robustness of a piezoelectric vibration absorber (PVA). PVAs are well known to be effective at suppressing the vibration of an adaptive structure; their weakness is low robustness to changes in the dynamic parameters of the system, including the main structure and the absorber. In the application to space structures, the temperature-dependency of capacitance of piezoelectric ceramics is the factor that causes performance reduction. To improve robustness to the temperature-dependency of the capacitance, this paper proposes a multiple-PVA system that is composed of distributed piezoelectric transducers and several shunt circuits. The optimization problems that determine both the frequencies and the damping ratios of the PVAs are multi-objective problems, which are solved using a real-coded genetic algorithm in this paper. A clamped aluminum beam with four groups of piezoelectric ceramics attached was considered in simulations and experiments. Numerical simulations revealed that the PVA systems designed using the proposed method had tolerance to changes in the capacitances. Furthermore, experiments using a thermostatic bath were conducted to reveal the effectiveness and robustness of the PVA systems. The maximum peaks of the transfer functions of the beam with the open circuit, the single-PVA system, the double-PVA system, and the quadruple-PVA system at 20 °C were 14.3 dB, −6.91 dB, −7.47 dB, and −8.51 dB, respectively. The experimental results also showed that the multiple-PVA system is more robust than a single PVA in a variable temperature environment from −10 °C to 50 °C. In conclusion, the use of multiple PVAs results in an effective, robust vibration control method for adaptive structures. (paper)
International Nuclear Information System (INIS)
Wang, Zhong-Min; Liu, Yan-Zhuang
2016-01-01
Highlights: • We investigate the transverse vibration of FGM pipe conveying fluid. • The FGM pipe conveying fluid can be classified into two cases. • The variations between the frequency and the power law exponent are obtained. • “Case 1” is relatively more reasonable than “case 2”. - Abstract: Problems related to the transverse vibration of pipe conveying fluid made of functionally graded material (FGM) are addressed. Based on inside and outside surface material compositions of the pipe, FGM pipe conveying fluid can be classified into two cases. It is hypothesized that the physical parameters of the material along the direction of the pipe wall thickness change in the simple power law. A differential equation of motion expressed in non-dimensional quantities is derived by using Hamilton's principle for systems of changing mass. Using the assuming modal method, the pipe deflection function is expanded into a series, in which each term is expressed to admissible function multiplied by generalized coordinate. Then, the differential equation of motion is discretized into the two order differential equations expressed in the generalized coordinates. Based on symplectic elastic theory and the introduction of dual system and dual variable, Hamilton's dual equations are derived, and the original problem is reduced to eigenvalue and eigenvector problem in the symplectic space. Finally, a symplectic method is employed to analyze the vibration and stability of FGM pipe conveying fluid. For a clamped–clamped FGM pipe conveying fluid in “case 1” and “case 2”, the dimensionless critical flow velocity for first-mode divergence and the critical coupled-mode flutter flow velocity are obtained, and the variations between the real part and imaginary part of dimensionless complex frequency and fluid velocity, mass ratio and the power law exponent (or graded index, volume fraction) for FGM pipe conveying fluid are analyzed.
Energy Technology Data Exchange (ETDEWEB)
Wang, Zhong-Min, E-mail: wangzhongm@xaut.edu.cn; Liu, Yan-Zhuang
2016-03-15
Highlights: • We investigate the transverse vibration of FGM pipe conveying fluid. • The FGM pipe conveying fluid can be classified into two cases. • The variations between the frequency and the power law exponent are obtained. • “Case 1” is relatively more reasonable than “case 2”. - Abstract: Problems related to the transverse vibration of pipe conveying fluid made of functionally graded material (FGM) are addressed. Based on inside and outside surface material compositions of the pipe, FGM pipe conveying fluid can be classified into two cases. It is hypothesized that the physical parameters of the material along the direction of the pipe wall thickness change in the simple power law. A differential equation of motion expressed in non-dimensional quantities is derived by using Hamilton's principle for systems of changing mass. Using the assuming modal method, the pipe deflection function is expanded into a series, in which each term is expressed to admissible function multiplied by generalized coordinate. Then, the differential equation of motion is discretized into the two order differential equations expressed in the generalized coordinates. Based on symplectic elastic theory and the introduction of dual system and dual variable, Hamilton's dual equations are derived, and the original problem is reduced to eigenvalue and eigenvector problem in the symplectic space. Finally, a symplectic method is employed to analyze the vibration and stability of FGM pipe conveying fluid. For a clamped–clamped FGM pipe conveying fluid in “case 1” and “case 2”, the dimensionless critical flow velocity for first-mode divergence and the critical coupled-mode flutter flow velocity are obtained, and the variations between the real part and imaginary part of dimensionless complex frequency and fluid velocity, mass ratio and the power law exponent (or graded index, volume fraction) for FGM pipe conveying fluid are analyzed.
Arslan, Hakan; Mansuroglu, Demet Sezgin; VanDerveer, Don; Binzet, Gun
2009-04-01
N-(2,2-Diphenylacetyl)- N'-(naphthalen-1yl)-thiourea (PANT) has been synthesized and characterized by elemental analysis, IR spectroscopy and 1H NMR spectroscopy. The crystal and molecular structure of the title compound has been determined from single crystal X-ray diffraction data. It crystallizes in the triclinic space group P-1, Z = 2 with a = 10.284(2) Å, b = 10.790(2) Å, c = 11.305(2) Å, α = 64.92(3)°, β = 89.88(3)°, γ = 62.99(3)°, V = 983.7(3) Å 3 and Dcalc = 1.339 Mg/m 3. The molecular structure, vibrational frequencies and infrared intensities of PANT were calculated by the Hartree-Fock and density functional theory methods (BLYP and B3LYP) using the 6-31G* basis set. The calculated geometric parameters were compared to the corresponding X-ray structure of the title compound. We obtained 22 stable conformers for the title compound; however Conformer 1 is approximately 9.53 kcal/mol more stable than Conformer 22. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of Conformer 17. The harmonic vibrations computed for this compound by the B3LYP/6-31G* method are in good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using the VEDA 4 program. A general better performance of the investigated methods was calculated by PAVF 1.0 program.
Comparative evaluation of different methods of treatment of miners with vibration-noise pathology
Energy Technology Data Exchange (ETDEWEB)
Bel' skaya, M.L.; Nekhorosheva, M.A.; Konovalova, S.I.; Kukhtina, G.V.; Gonchar, I.G.; Terent' eva, D.P.; Grishchenko, L.A.; Soboleva, N.P.; Kharitonov, S.A.; Priklonskii, I.V.
1984-10-01
Two new therapeutic methods of treating vibration-noise pathology, needle acupuncture and hyperbaric oxygenation, are compared with established methods of medical and physical therapy. Four complexes of therapy are recommended: I complex (control), medication and physical therapy; II complex, acupuncture and medical therapy; III complex, acupuncture, medical and physical therapy; IV complex, hyperbaric oxygenation, medical and physical therapy. The four complexes were tested on a selected group of miners. II, III and IV complexes were correlated with control (I) on the basis of subjective signs, objective changes in nervous system and functional state of vegetative and peripheral nervous system. A table compares the effectiveness of II, III, IV complexes with I complex. Results confirm effectiveness of medical and physical therapy. Application of acupuncture increases benefits to cardiovascular system and hyperbaric therapy aids neurosensory hearing impairment. As a result of investigation, acupuncture and hyperbaric therapy are recommended for treatment of patients suffering vibration-noise pathology with a differential approach to their purpose. 8 references.
Vibration isolation design for periodically stiffened shells by the wave finite element method
Hong, Jie; He, Xueqing; Zhang, Dayi; Zhang, Bing; Ma, Yanhong
2018-04-01
Periodically stiffened shell structures are widely used due to their excellent specific strength, in particular for aeronautical and astronautical components. This paper presents an improved Wave Finite Element Method (FEM) that can be employed to predict the band-gap characteristics of stiffened shell structures efficiently. An aero-engine casing, which is a typical periodically stiffened shell structure, was employed to verify the validation and efficiency of the Wave FEM. Good agreement has been found between the Wave FEM and the classical FEM for different boundary conditions. One effective wave selection method based on the Wave FEM has thus been put forward to filter the radial modes of a shell structure. Furthermore, an optimisation strategy by the combination of the Wave FEM and genetic algorithm was presented for periodically stiffened shell structures. The optimal out-of-plane band gap and the mass of the whole structure can be achieved by the optimisation strategy under an aerodynamic load. Results also indicate that geometric parameters of stiffeners can be properly selected that the out-of-plane vibration attenuates significantly in the frequency band of interest. This study can provide valuable references for designing the band gaps of vibration isolation.
About a sequential method for non destructive testing of structures by mechanical vibrations
International Nuclear Information System (INIS)
Suarez Antola, R.
2001-01-01
The presence and growth of cracks voids or fields of pores under applied forces or environmental actions can produce a meaningful lowering in the proper frequencies of normal modes of mechanical vibration in structures.A quite general expression for the square of modes proper frequency as a functional of displacement field,density field and elastic moduli fields is used as a starting point.The effect of defects on frequency are modeled as equivalent changes in density and elastic moduli fields,introducing the concept of region of influence of each defect.An approximate expression is obtained which relates the relative lowering in the square of modes proper frequency with position,size,shape and orientation of defects in mode displacement field.Some simple examples of structural elements with cracks or fields of pores are considered.the connection with linear elastic fracture mechanics is briefly exemplified.A sequential method is proposed for non-destructive testing of structures using mechanical vibrations combined with properly chosen local nondestructive testing methods
International Nuclear Information System (INIS)
Chen, H.T.; Muether, H.; Faessler, A.
1978-01-01
Pairing vibrational and isospin rotational states are described in different approximations based on particle number and isospin projected, proton-proton, neutron-neutron and proton-neutron pairing wave functions and on the generator coordinate method (GCM). The investigations are performed in models for which an exact group theoretical solution exists. It turns out that a particle number and isospin projection is essential to yield a good approximation to the ground state or isospin yrast state energies. For strong pairing correlations (pairing force constant equal to the single-particle level distance) isospin cranking (-ωTsub(x)) yields with particle number projected pairing wave function also good agreement with the exact energies. GCM wave functions generated by particle number and isospin projected BCS functions with different amounts of pairing correlations yield for the lowest T=0 and T=2 states energies which are practically indistinguishable from the exact solutions. But even the second and third lowest energies of charge-symmetric states are still very reliable. Thus it is concluded that also in realistic cases isospin rotational and pairing vibrational states may be described in the framework of the GCM method with isospin and particle number projected generating wave functions. (Auth.)
Application of empirical mode decomposition method for characterization of random vibration signals
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Setyamartana Parman
2016-07-01
Full Text Available Characterization of finite measured signals is a great of importance in dynamical modeling and system identification. This paper addresses an approach for characterization of measured random vibration signals where the approach rests on a method called empirical mode decomposition (EMD. The applicability of proposed approach is tested in one numerical and experimental data from a structural system, namely spar platform. The results are three main signal components, comprising: noise embedded in the measured signal as the first component, first intrinsic mode function (IMF called as the wave frequency response (WFR as the second component and second IMF called as the low frequency response (LFR as the third component while the residue is the trend. Band-pass filter (BPF method is taken as benchmark for the results obtained from EMD method.
Vibrational methods of the overhead gas-pipelines technological equipment diagnostics
International Nuclear Information System (INIS)
Zakhezin, A.M.; Malysheva, T.V.
2001-01-01
The diagnostic methods of overhead gas-pipelines of the technical equipment of gas-compressor station are considered in this article by carrying out registration certification documentation. Some faults of overhead technical gas-pipelines have been proposed. This paper is devoted to the diagnostic methods of the whole gas- pipelines and their parts for some faults during expert checking fulfillment and carrying out registration certification documentation. The analysis of all defects allows to determine a 'between-repairs interval', to develop some operations to avoid these faults and to estimate the repair operation quality, to reduce failure probability. As an example of the effectiveness of technical condition service of vibrational methods by expertise fulfillment have been considered for some defects of the overhead pipelines. (author)
Mulder, Emma R; de Jong, Remko A; Knol, Dirk L; van Schijndel, Ronald A; Cover, Keith S; Visser, Pieter J; Barkhof, Frederik; Vrenken, Hugo
2014-05-15
To measure hippocampal volume change in Alzheimer's disease (AD) or mild cognitive impairment (MCI), expert manual delineation is often used because of its supposed accuracy. It has been suggested that expert outlining yields poorer reproducibility as compared to automated methods, but this has not been investigated. To determine the reproducibilities of expert manual outlining and two common automated methods for measuring hippocampal atrophy rates in healthy aging, MCI and AD. From the Alzheimer's Disease Neuroimaging Initiative (ADNI), 80 subjects were selected: 20 patients with AD, 40 patients with mild cognitive impairment (MCI) and 20 healthy controls (HCs). Left and right hippocampal volume change between baseline and month-12 visit was assessed by using expert manual delineation, and by the automated software packages FreeSurfer (longitudinal processing stream) and FIRST. To assess reproducibility of the measured hippocampal volume change, both back-to-back (BTB) MPRAGE scans available for each visit were analyzed. Hippocampal volume change was expressed in μL, and as a percentage of baseline volume. Reproducibility of the 1-year hippocampal volume change was estimated from the BTB measurements by using linear mixed model to calculate the limits of agreement (LoA) of each method, reflecting its measurement uncertainty. Using the delta method, approximate p-values were calculated for the pairwise comparisons between methods. Statistical analyses were performed both with inclusion and exclusion of visibly incorrect segmentations. Visibly incorrect automated segmentation in either one or both scans of a longitudinal scan pair occurred in 7.5% of the hippocampi for FreeSurfer and in 6.9% of the hippocampi for FIRST. After excluding these failed cases, reproducibility analysis for 1-year percentage volume change yielded LoA of ±7.2% for FreeSurfer, ±9.7% for expert manual delineation, and ±10.0% for FIRST. Methods ranked the same for reproducibility of 1
Kamarudin, A. F.; Mokhatar, S. N.; Zainal Abidin, M. H.; Daud, M. E.; Rosli, M. S.; Ibrahim, A.; Ibrahim, Z.; Noh, M. S. Md
2018-04-01
Monitoring of structural health from initial stage of building construction to its serviceability is an ideal practise to assess for any structural defects or damages. Structural integrity could be intruded by natural destruction or structural deterioration, and worse if without remedy action on monitoring, building re-assessment or maintenance is taken. In this study the application of ambient vibration (AV) testing is utilized to evaluate the health of eighth stories medium rise reinforced concrete building in Universiti Tun Hussein Onn Malaysia (UTHM), based comparison made between the predominant frequency, fo, determined in year 2012 and 2017. For determination of fo, popular method of Fourier Amplitude Spectra (FAS) was used to transform the ambient vibration time series by using 1 Hz tri-axial seismometer sensors and City SharkII data recorder. From the results, it shows the first mode frequencies from FAS curves indicate at 2.04 Hz in 2012 and 1.97 Hz in 2017 with only 3.14% of frequency reduction. However, steady state frequencies shown at the second and third modes frequencies of 2.42 Hz and 3.31 Hz by both years. Two translation mode shapes were found at the first and second mode frequencies in the North-South (NS-parallel to building transverse axis) and East-West (EsW-parallel to building longitudinal axis) components, and the torsional mode shape shows as the third mode frequency in both years. No excessive deformation amplitude was found at any selective floors based on comparison made between three mode shapes produced, that could bring to potential feature of structural deterioration. Low percentages of natural frequency disparity within five years of duration interval shown by the first mode frequencies under ambient vibration technique was considered in good health state, according to previous researchers recommendation at acceptable percentages below 5 to 10% over the years.
Lai, Wenqing; Wang, Yuandong; Li, Wenpeng; Sun, Guang; Qu, Guomin; Cui, Shigang; Li, Mengke; Wang, Yongqiang
2017-10-01
Based on long term vibration monitoring of the No.2 oil-immersed fat wave reactor in the ±500kV converter station in East Mongolia, the vibration signals in normal state and in core loose fault state were saved. Through the time-frequency analysis of the signals, the vibration characteristics of the core loose fault were obtained, and a fault diagnosis method based on the dual tree complex wavelet (DT-CWT) and support vector machine (SVM) was proposed. The vibration signals were analyzed by DT-CWT, and the energy entropy of the vibration signals were taken as the feature vector; the support vector machine was used to train and test the feature vector, and the accurate identification of the core loose fault of the flat wave reactor was realized. Through the identification of many groups of normal and core loose fault state vibration signals, the diagnostic accuracy of the result reached 97.36%. The effectiveness and accuracy of the method in the fault diagnosis of the flat wave reactor core is verified.
International Nuclear Information System (INIS)
Inada, Fumio; Nishihara, Takashi; Yasuo, Akira; Morita, Ryo
2002-01-01
The applicability of the cross-shaped tube bundle as a lower plenum component of pressure vessel is examined to develop a next generation LWR in Japanese electric utilities. The flow-induced vibration characteristics are not understood well. Methods to evaluate turbulence induced vibration and vortex induced vibration were proposed by CRIEPI. In this study, vibration response is obtained experimentally to propose a method to evaluate self-excited vibration of cross-shaped tube bundle. The self-excited vibration was found to be generated when nondimensional flow velocity was above a critical value. The nondimensional critical velocity of normal configuration is 15% smaller than that of staggered configuration, which means that the nondimensional critical velocity of normal configuration can give conservative evaluation. The result of Reynolds number Re=6.2 x 10 4 agrees well with that of Re=6.8 x 10 5 , in which region, the effect of Reynolds number on the critical velocity is small. (author)
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Zheng Hu
2015-01-01
Full Text Available High-speed blades are often prone to fatigue due to severe blade vibrations. In particular, synchronous vibrations can cause irreversible damages to the blade. Blade tip-timing methods (BTT have become a promising way to monitor blade vibrations. However, synchronous vibrations are unsuitably monitored by uniform BTT sampling. Therefore, non-equally mounted probes have been used, which will result in the non-uniformity of the sampling signal. Since under-sampling is an intrinsic drawback of BTT methods, how to analyze non-uniformly under-sampled BTT signals is a big challenge. In this paper, a novel reconstruction method for non-uniformly under-sampled BTT data is presented. The method is based on the periodically non-uniform sampling theorem. Firstly, a mathematical model of a non-uniform BTT sampling process is built. It can be treated as the sum of certain uniform sample streams. For each stream, an interpolating function is required to prevent aliasing in the reconstructed signal. Secondly, simultaneous equations of all interpolating functions in each sub-band are built and corresponding solutions are ultimately derived to remove unwanted replicas of the original signal caused by the sampling, which may overlay the original signal. In the end, numerical simulations and experiments are carried out to validate the feasibility of the proposed method. The results demonstrate the accuracy of the reconstructed signal depends on the sampling frequency, the blade vibration frequency, the blade vibration bandwidth, the probe static offset and the number of samples. In practice, both types of blade vibration signals can be particularly reconstructed by non-uniform BTT data acquired from only two probes.
Ideguchi, Tsuyoshi; Yoshida, Ryujyu; Ooshima, Keita
We examined how test subject impressions of music changed when artificial vibrations were incorporated as constituent elements of a musical composition. In this study, test subjects listened to several music samples in which different types of artificial vibration had been incorporated and then subjectively evaluated any resulting changes to their impressions of the music. The following results were obtained: i) Even if rhythm vibration is added to a silent component of a musical composition, it can effectively enhance musical fitness. This could be readily accomplished when actual sounds that had been synchronized with the vibration components were provided beforehand. ii) The music could be listened to more comfortably by adding not only a natural vibration extracted from percussion instruments but also artificial vibration as tactile stimulation according to intentional timing. Furthermore, it was found that the test subjects' impression of the music was affected by a characteristic of the artificial vibration. iii) Adding vibration to high-frequency areas can offer an effective and practical way of enhancing the appeal of a musical composition. iv) The movement sensations of sound and vibration could be experienced when the strength of the sound and vibration are modified in turn. These results suggest that the intentional application of artificial vibration could result in a sensitivity amplification factor on the part of a listener.
Modal mass estimation from ambient vibrations measurement: A method for civil buildings
Acunzo, G.; Fiorini, N.; Mori, F.; Spina, D.
2018-01-01
A new method for estimating the modal mass ratios of buildings from unscaled mode shapes identified from ambient vibrations is presented. The method is based on the Multi Rigid Polygons (MRP) model in which each floor of the building is ideally divided in several non-deformable polygons that move independent of each other. The whole mass of the building is concentrated in the centroid of the polygons and the experimental mode shapes are expressed in term of rigid translations and of rotations. In this way, the mass matrix of the building can be easily computed on the basis of simple information about the geometry and the materials of the structure. The modal mass ratios can be then obtained through the classical equation of structural dynamics. Ambient vibrations measurement must be performed according to this MRP models, using at least two biaxial accelerometers per polygon. After a brief illustration of the theoretical background of the method, numerical validations are presented analysing the method sensitivity for possible different source of errors. Quality indexes are defined for evaluating the approximation of the modal mass ratios obtained from a certain MRP model. The capability of the proposed model to be applied to real buildings is illustrated through two experimental applications. In the first one, a geometrically irregular reinforced concrete building is considered, using a calibrated Finite Element Model for validating the results of the method. The second application refers to a historical monumental masonry building, with a more complex geometry and with less information available. In both cases, MRP models with a different number of rigid polygons per floor are compared.
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.
Seismic analysis methods for LMFBR core and verification with mock-up vibration tests
International Nuclear Information System (INIS)
Sasaki, Y.; Kobayashi, T.; Fujimoto, S.
1988-01-01
This paper deals with the vibration behaviors of a cluster of core elements with the hexagonal cross section in a barrel under the dynamic excitation due to seismic events. When a strong earthquake excitation is applied to the core support, the cluster of core elements displace to a geometrical limit determined by restraint rings in the barrel, and collisions could occur between adjacent elements as a result of their relative motion. For these reasons, seismic analysis on LMFBR core elements is a complicated non-linear vibration problem, which includes collisions and fluid interactions. In an actual core design, it is hard to include hundreds of elements in the numerical calculations. In order to study the seismic behaviors of core elements, experiments with single row 29 elements (17 core fuel assemblies, 4 radial blanket assemblies, and 8 neutron shield assemblies) simulated all elements in MONJU core central row, and experiments with 7 cluster rows of 37 core fuel assemblies in the core center were performed in a fluid filled tank, using a large-sized shaking table. Moreover, the numerical analyses of these experiments were performed for the validation of simplified and detailed analytical methods. 4 refs, 18 figs
Automatic crack detection method for loaded coal in vibration failure process.
Directory of Open Access Journals (Sweden)
Chengwu Li
Full Text Available In the coal mining process, the destabilization of loaded coal mass is a prerequisite for coal and rock dynamic disaster, and surface cracks of the coal and rock mass are important indicators, reflecting the current state of the coal body. The detection of surface cracks in the coal body plays an important role in coal mine safety monitoring. In this paper, a method for detecting the surface cracks of loaded coal by a vibration failure process is proposed based on the characteristics of the surface cracks of coal and support vector machine (SVM. A large number of cracked images are obtained by establishing a vibration-induced failure test system and industrial camera. Histogram equalization and a hysteresis threshold algorithm were used to reduce the noise and emphasize the crack; then, 600 images and regions, including cracks and non-cracks, were manually labelled. In the crack feature extraction stage, eight features of the cracks are extracted to distinguish cracks from other objects. Finally, a crack identification model with an accuracy over 95% was trained by inputting the labelled sample images into the SVM classifier. The experimental results show that the proposed algorithm has a higher accuracy than the conventional algorithm and can effectively identify cracks on the surface of the coal and rock mass automatically.
Grolet, Aurelien; Thouverez, Fabrice
2015-02-01
This paper is devoted to the study of vibration of mechanical systems with geometric nonlinearities. The harmonic balance method is used to derive systems of polynomial equations whose solutions give the frequency component of the possible steady states. Groebner basis methods are used for computing all solutions of polynomial systems. This approach allows to reduce the complete system to an unique polynomial equation in one variable driving all solutions of the problem. In addition, in order to decrease the number of variables, we propose to first work on the undamped system, and recover solution of the damped system using a continuation on the damping parameter. The search for multiple solutions is illustrated on a simple system, where the influence of the retained number of harmonic is studied. Finally, the procedure is applied on a simple cyclic system and we give a representation of the multiple states versus frequency.
Arjunan, V; Thillai Govindaraja, S; Jayapraksh, A; Mohan, S
2013-04-15
Quantum chemical calculations of energy, structural parameters and vibrational wavenumbers of 4-bromoisoquinoline (4BIQ) were carried out by using B3LYP method using 6-311++G(**), cc-pVTZ and LANL2DZ basis sets. The optimised geometrical parameters obtained by DFT calculations are in good agreement with electron diffraction data. Interpretations of the experimental FTIR and FT-Raman spectra have been reported with the aid of the theoretical wavenumbers. The differences between the observed and scaled wavenumber values of most of the fundamentals are very small. The thermodynamic parameters have also been computed. Electronic properties of the molecule were discussed through the molecular electrostatic potential surface, HOMO-LUMO energy gap and NBO analysis. To provide precise assignments of (1)H and (13)CNMR spectra, isotropic shielding and chemical shifts were calculated with the Gauge-Invariant Atomic Orbital (GIAO) method. Copyright © 2013 Elsevier B.V. All rights reserved.
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E. O. Zaitsev
2016-01-01
Full Text Available The objective of this paper is development and experimental verification special software of spectral analysis. Spectral analysis use of controlled vibrations objects. Spectral analysis of vibration based on use maximum-entropy autoregressive method of spectral analysis by the Berg algorithm. For measured signals use preliminary analysis based on regression analysis. This analysis of the signal enables to eliminate uninformative parameters such as – the noise and the trend. For preliminary analysis developed special software tools. Non-contact measurement of mechanical vibrations parameters rotating diffusely-reflecting surfaces used in circumstances where the use of contact sensors difficult or impossible for a number of reasons, including lack of access to the object, the small size of the controlled area controlled portion has a high temperature or is affected by strong electromagnetic fields. For control use offered laser measuring system. This measuring system overcomes the shortcomings interference or Doppler optical measuring systems. Such as measure the large amplitude and inharmonious vibration. On the basis of the proposed methods developed special software tools for use measuring laser system. LabVIEW using for developed special software. Experimental research of the proposed method of vibration signals processing is checked in the analysis of the diagnostic information obtained by measuring the vibration system grinding diamond wheel cold solid tungsten-containing alloy TK8. A result of work special software tools was complex spectrum obtained «purified» from non-informative parameters. Spectrum of the signal corresponding to the vibration process observed object.
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A Safrangian
2017-05-01
Full Text Available Introduction Vibrations include a wide range of engineering sciences and discuss from different aspects. One of the aspects is related to various types of engines vibrations, which are often used as power sources in agriculture. The created vibrations can cause lack of comfort and reduce effective work and have bad influence on the health and safety. One of the important parameters of the diesel engine that has the ability to create vibration and knocking is the type of fuel. In this study, the effects of different blends of biodiesel, bioethanol and diesel on the engine vibration were investigated. As a result, a blend of fuels such as synthetic fuel that creates less vibration engine can be identified and introduced. Materials and Methods In this study, canola oil and methanol alcohol with purity of 99.99% and the molar ratio of 6:1 and sodium hydroxide catalyst with 1% by weight of oil were used for biodiesel production. Reactor configurations include: maintaining the temperature at 50 ° C, the reaction time of 5 minutes and the intensity of mixing (8000 rpm, and pump flow, 0.83 liters per minute. A Massey Ferguson (MF 285 tractor with single differential (2WD, built in 2012 at Tractor factory of Iran was used for the experiment. To measure the engine vibration signals, an oscillator with model of VM120 British MONITRAN was used. Vibration signals were measured at three levels of engine speed (2000, 1600, 1000 rpm in three directions (X, Y, Z. The analysis performed by two methods in this study: statistical data analysis and data analysis using Adaptive neuro-fuzzy inference system (ANFIS. Statistical analysis of data: a factorial experiment of 10×3 based on completely randomized design with three replications was used in each direction of X, Y and Z that conducted separately. Data were compiled and analyzed by SPSS 19 software. Ten levels of fuel were including of biodiesel (5, 15 and 25% and bioethanol (2, 4 and 6%, and diesel fuel. Data
Gray bootstrap method for estimating frequency-varying random vibration signals with small samples
Directory of Open Access Journals (Sweden)
Wang Yanqing
2014-04-01
Full Text Available During environment testing, the estimation of random vibration signals (RVS is an important technique for the airborne platform safety and reliability. However, the available methods including extreme value envelope method (EVEM, statistical tolerances method (STM and improved statistical tolerance method (ISTM require large samples and typical probability distribution. Moreover, the frequency-varying characteristic of RVS is usually not taken into account. Gray bootstrap method (GBM is proposed to solve the problem of estimating frequency-varying RVS with small samples. Firstly, the estimated indexes are obtained including the estimated interval, the estimated uncertainty, the estimated value, the estimated error and estimated reliability. In addition, GBM is applied to estimating the single flight testing of certain aircraft. At last, in order to evaluate the estimated performance, GBM is compared with bootstrap method (BM and gray method (GM in testing analysis. The result shows that GBM has superiority for estimating dynamic signals with small samples and estimated reliability is proved to be 100% at the given confidence level.
Rong, Bao; Rui, Xiaoting; Lu, Kun; Tao, Ling; Wang, Guoping; Ni, Xiaojun
2018-05-01
In this paper, an efficient method of dynamics modeling and vibration control design of a linear hybrid multibody system (MS) is studied based on the transfer matrix method. The natural vibration characteristics of a linear hybrid MS are solved by using low-order transfer equations. Then, by constructing the brand-new body dynamics equation, augmented operator and augmented eigenvector, the orthogonality of augmented eigenvector of a linear hybrid MS is satisfied, and its state space model expressed in each independent model space is obtained easily. According to this dynamics model, a robust independent modal space-fuzzy controller is designed for vibration control of a general MS, and the genetic optimization of some critical control parameters of fuzzy tuners is also presented. Two illustrative examples are performed, which results show that this method is computationally efficient and with perfect control performance.
Energy Technology Data Exchange (ETDEWEB)
Funaki, T.; Hayashi, S. [Osaka University, Osaka (Japan). Faculty of engineering
1996-12-31
It is known in estimating vibration characteristics of a ship that fluid range affects largely a structure. In order to analyze the compound vibration therein, a method was proposed, which estimates vibration levels without using the finite element method. However, the problem of mode decay ratio has not been solved. Therefore, this paper first describes a method to introduce an equivalent linear decay matrix. The paper then mentions difference in the decay effects due to fluid viscosity in a shallow and deep water regions. Furthermore, vibration levels in the deep water region were estimated in a model experiment to verify the estimation result. Under a hypothesis that two-node vibration in a rotating ellipse has displacement distributions in the deep and shallow water regions equivalent, and when a case of vibration in a layer flow condition is calculated, dissipation energy in the shallow region is larger than that in the deep region by about 26%. About 5% of the total dissipation energy is consumed at bottom of the sea. According to a frequency response calculation, estimated values for the response levels still differ from experimental values, although the trend that the vibration levels change can be reproduced. 6 refs., 15 figs., 2 tabs.
Energy Technology Data Exchange (ETDEWEB)
Funaki, T; Hayashi, S [Osaka University, Osaka (Japan). Faculty of engineering
1997-12-31
It is known in estimating vibration characteristics of a ship that fluid range affects largely a structure. In order to analyze the compound vibration therein, a method was proposed, which estimates vibration levels without using the finite element method. However, the problem of mode decay ratio has not been solved. Therefore, this paper first describes a method to introduce an equivalent linear decay matrix. The paper then mentions difference in the decay effects due to fluid viscosity in a shallow and deep water regions. Furthermore, vibration levels in the deep water region were estimated in a model experiment to verify the estimation result. Under a hypothesis that two-node vibration in a rotating ellipse has displacement distributions in the deep and shallow water regions equivalent, and when a case of vibration in a layer flow condition is calculated, dissipation energy in the shallow region is larger than that in the deep region by about 26%. About 5% of the total dissipation energy is consumed at bottom of the sea. According to a frequency response calculation, estimated values for the response levels still differ from experimental values, although the trend that the vibration levels change can be reproduced. 6 refs., 15 figs., 2 tabs.
Free Vibration Characteristics of Cylindrical Shells Using a Wave Propagation Method
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A. Ghoshal
2001-01-01
Full Text Available In the present paper, concept of a periodic structure is used to study the characteristics of the natural frequencies of a complete unstiffened cylindrical shell. A segment of the shell between two consecutive nodal points is chosen to be a periodic structural element. The present effort is to modify Mead and Bardell's approach to study the free vibration characteristics of unstiffened cylindrical shell. The Love-Timoshenko formulation for the strain energy is used in conjunction with Hamilton's principle to compute the natural propagation constants for two shell geometries and different circumferential nodal patterns employing Floquet's principle. The natural frequencies were obtained using Sengupta's method and were compared with those obtained from classical Arnold-Warburton's method. The results from the wave propagation method were found to compare identically with the classical methods, since both the methods lead to the exact solution of the same problem. Thus consideration of the shell segment between two consecutive nodal points as a periodic structure is validated. The variations of the phase constants at the lower bounding frequency for the first propagation band for different nodal patterns have been computed. The method is highly computationally efficient.
Reduction method for residual stress of welded joint using harmonic vibrational load
International Nuclear Information System (INIS)
Aoki, Shigeru; Nishimura, Tadashi; Hiroi, Tetsumaro; Hirai, Seiji
2007-01-01
Welding is widely used for construction of many structures. Since welding is a process using locally given heat, residual stress is generated near the bead. Tensile residual stress degrades fatigue strength. Some reduction methods of residual stress have been presented and, for example, heat treatment and shot peening are practically used. However, those methods need special tools and are time consuming. In this paper, a new method for reduction of residual stress using harmonic vibrational load during welding is proposed. The proposed method is examined experimentally for some conditions. Two thin plates are supported on the supporting device and butt-welded using an automatic CO 2 gas shielded arc welding machine. Residual stress in the direction of the bead is measured by using a paralleled beam X-ray diffractometer with scintillation counter after removing quenched scale chemically. First, the welding of rolled steel for general structure for some excitation frequencies is examined. Specimens are welded along the groove on both sides. For all frequencies, tensile residual stress near the bead is significantly reduced. Second, welding of the specimen made of high tensile strength steel is examined. In this case, tensile residual stress near the bead is also reduced. Finally, the proposed method is examined by an analytical method. An analytical model which consists of mass and preloaded springs with elasto-plastic characteristic is used. Reduction of residual stress is demonstrated using this model
International Nuclear Information System (INIS)
Avila, Gustavo; Carrington, Tucker
2015-01-01
In this paper, we improve the collocation method for computing vibrational spectra that was presented in Avila and Carrington, Jr. [J. Chem. Phys. 139, 134114 (2013)]. Using an iterative eigensolver, energy levels and wavefunctions are determined from values of the potential on a Smolyak grid. The kinetic energy matrix-vector product is evaluated by transforming a vector labelled with (nondirect product) grid indices to a vector labelled by (nondirect product) basis indices. Both the transformation and application of the kinetic energy operator (KEO) scale favorably. Collocation facilitates dealing with complicated KEOs because it obviates the need to calculate integrals of coordinate dependent coefficients of differential operators. The ideas are tested by computing energy levels of HONO using a KEO in bond coordinates
Approximations to the Probability of Failure in Random Vibration by Integral Equation Methods
DEFF Research Database (Denmark)
Nielsen, Søren R.K.; Sørensen, John Dalsgaard
Close approximations to the first passage probability of failure in random vibration can be obtained by integral equation methods. A simple relation exists between the first passage probability density function and the distribution function for the time interval spent below a barrier before...... passage probability density. The results of the theory agree well with simulation results for narrow banded processes dominated by a single frequency, as well as for bimodal processes with 2 dominating frequencies in the structural response....... outcrossing. An integral equation for the probability density function of the time interval is formulated, and adequate approximations for the kernel are suggested. The kernel approximation results in approximate solutions for the probability density function of the time interval, and hence for the first...
Directory of Open Access Journals (Sweden)
Zhiqiang Shen
2012-01-01
Full Text Available Deformation of partially composite beams under distributed loading and free vibrations of partially composite beams under various boundary conditions are examined in this paper. The weak-form quadrature element method, which is characterized by direct evaluation of the integrals involved in the variational description of a problem, is used. One quadrature element is normally sufficient for a partially composite beam regardless of the magnitude of the shear connection stiffness. The number of integration points in a quadrature element is adjustable in accordance with convergence requirement. Results are compared with those of various finite element formulations. It is shown that the weak form quadrature element solution for partially composite beams is free of slip locking, and high computational accuracy is achieved with smaller number of degrees of freedom. Besides, it is found that longitudinal inertia of motion cannot be simply neglected in assessment of dynamic behavior of partially composite beams.
Petrenko, Taras; Rauhut, Guntram
2017-03-01
Vibrational configuration interaction theory is a common method for calculating vibrational levels and associated IR and Raman spectra of small and medium-sized molecules. When combined with appropriate configuration selection procedures, the method allows the treatment of configuration spaces with up to 1010 configurations. In general, this approach pursues the construction of the eigenstates with significant contributions of physically relevant configurations. The corresponding eigenfunctions are evaluated in the subspace of selected configurations. However, it can easily reach the dimension which is not tractable for conventional eigenvalue solvers. Although Davidson and Lanczos methods are the methods of choice for calculating exterior eigenvalues, they usually fall into stagnation when applied to interior states. The latter are commonly treated by the Jacobi-Davidson method. This approach in conjunction with matrix factorization for solving the correction equation (CE) is prohibitive for larger problems, and it has limited efficiency if the solution of the CE is based on Krylov's subspace algorithms. We propose an iterative subspace method that targets the eigenvectors with significant contributions to a given reference vector and is based on the optimality condition for the residual norm corresponding to the error in the solution vector. The subspace extraction and expansion are modified according to these principles which allow very efficient calculation of interior vibrational states with a strong multireference character in different vibrational structure problems. The convergence behavior of the method and its performance in comparison with the aforementioned algorithms are investigated in a set of benchmark calculations.
Energy Technology Data Exchange (ETDEWEB)
Balci, Murat [Dept. of Mechanical Engineering, Bayburt University, Bayburt (Turkmenistan); Gundogdu, Omer [Dept. of Mechanical Engineering, Ataturk University, Erzurum (Turkmenistan)
2017-01-15
In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed.
International Nuclear Information System (INIS)
Balci, Murat; Gundogdu, Omer
2017-01-01
In this study, estimation of some physical properties of a laminated composite plate was conducted via the inverse vibration problem. Laminated composite plate was modelled and simulated to obtain vibration responses for different length-to-thickness ratio in ANSYS. Furthermore, a numerical finite element model was developed for the laminated composite utilizing the Kirchhoff plate theory and programmed in MATLAB for simulations. Optimizing the difference between these two vibration responses, inverse vibration problem was solved to obtain some of the physical properties of the laminated composite using genetic algorithms. The estimated parameters are compared with the theoretical results, and a very good correspondence was observed
Altazi, Baderaldeen A; Zhang, Geoffrey G; Fernandez, Daniel C; Montejo, Michael E; Hunt, Dylan; Werner, Joan; Biagioli, Matthew C; Moros, Eduardo G
2017-11-01
Site-specific investigations of the role of radiomics in cancer diagnosis and therapy are emerging. We evaluated the reproducibility of radiomic features extracted from 18 Flourine-fluorodeoxyglucose ( 18 F-FDG) PET images for three parameters: manual versus computer-aided segmentation methods, gray-level discretization, and PET image reconstruction algorithms. Our cohort consisted of pretreatment PET/CT scans from 88 cervical cancer patients. Two board-certified radiation oncologists manually segmented the metabolic tumor volume (MTV 1 and MTV 2 ) for each patient. For comparison, we used a graphical-based method to generate semiautomated segmented volumes (GBSV). To address any perturbations in radiomic feature values, we down-sampled the tumor volumes into three gray-levels: 32, 64, and 128 from the original gray-level of 256. Finally, we analyzed the effect on radiomic features on PET images of eight patients due to four PET 3D-reconstruction algorithms: maximum likelihood-ordered subset expectation maximization (OSEM) iterative reconstruction (IR) method, fourier rebinning-ML-OSEM (FOREIR), FORE-filtered back projection (FOREFBP), and 3D-Reprojection (3DRP) analytical method. We extracted 79 features from all segmentation method, gray-levels of down-sampled volumes, and PET reconstruction algorithms. The features were extracted using gray-level co-occurrence matrices (GLCM), gray-level size zone matrices (GLSZM), gray-level run-length matrices (GLRLM), neighborhood gray-tone difference matrices (NGTDM), shape-based features (SF), and intensity histogram features (IHF). We computed the Dice coefficient between each MTV and GBSV to measure segmentation accuracy. Coefficient values close to one indicate high agreement, and values close to zero indicate low agreement. We evaluated the effect on radiomic features by calculating the mean percentage differences (d¯) between feature values measured from each pair of parameter elements (i.e. segmentation methods: MTV
International Nuclear Information System (INIS)
Granger, S.; Perotin, L.
1997-01-01
Maintaining the PWR components under reliable operating conditions requires a complex design to prevent various damaging processes, including fatigue and wear problems due to flow-induced vibration. In many practical situations, it is difficult, if not impossible, to perform direct measurements or calculations of the external forces acting on vibrating structures. Instead, vibrational responses can often be conveniently measured. This paper presents an inverse method for estimating a distributed random excitation from the measurement of the structural response at a number of discrete points. This paper is devoted to the presentation of the theoretical development. The force identification method is based on a modal model for the structure and a spatial orthonormal decomposition of the excitation field. The estimation of the Fourier coefficients of this orthonormal expansion is presented. As this problem turns out to be ill-posed, a regularization process is introduced. The minimization problem associated to this process is then formulated and its solutions is developed. (author)
International Nuclear Information System (INIS)
Nieradka, K.; MaloziePc, G.; Kopiec, D.; Gotszalk, T.; Grabiec, P.; Janus, P.; Sierakowski, A.
2011-01-01
Here we present an extension of optical beam deflection (OBD) method for measuring displacement and vibrations of an array of microcantilevers. Instead of focusing on the cantilever, the optical beam is either focused above or below the cantilever array, or focused only in the axis parallel to the cantilevers length, allowing a wide optical line to span multiple cantilevers in the array. Each cantilever reflects a part of the incident beam, which is then directed onto a photodiode array detector in a manner allowing distinguishing between individual beams. Each part of reflected beam behaves like a single beam of roughly the same divergence angle in the bending sensing axis as the incident beam. Since sensitivity of the OBD method depends on the divergence angle of deflected beam, high sensitivity is preserved in proposed expanded beam deflection (EBD) method. At the detector, each spot's position is measured at the same time, without time multiplexing of light sources. This provides real simultaneous readout of entire array, unavailable in most of competitive methods, and thus increases time resolution of the measurement. Expanded beam can also span another line of cantilevers allowing monitoring of specially designed two-dimensional arrays. In this paper, we present first results of application of EBD method to cantilever sensors. We show how thermal noise resolution can be easily achieved and combined with thermal noise based resonance frequency measurement.
Directory of Open Access Journals (Sweden)
Anatoliy Alexandrovich Bogoyavlenskiy
2017-01-01
Full Text Available On the basis of system approach the structure of the aviation activity areas on air transport related to monitoring and measurements of vibration parameters is presented.The technology analysis of laboratory tests of the onboard equipment control of vibration parameters is carried out. The issues related to ensuring the unity of measurements of vibration parameters are researched and summarized.While dealing with the works on metrological certification described in the article, the risks arising from aviation activity on air transport are taken into account. The certification methods of measuring channels of vibration parametersused on stands for testing GTE at the repairing of aircraft engines are developed. The methods are implemented when con- ducting initial and periodic certifications of test benches for twelve types of aircraft GTE in repair organizations. The reliability of the results of the conducted research due to the fact that they were carried out with the use of certified measure- ment equipment, included in the State register of measuring instruments. The research is conducted for a sufficiently high statistical confidence level with the boundaries 0.95. The studies have shown that running on air transport measurements of vibration parameters are metrologically se- cured, the unity of measurements and their traceability from the national primary reference to special measuring instru- ments, test equipment, and onboard controls of the aircraft is maintained.
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
Fuzzy norm method for evaluating random vibration of airborne platform from limited PSD data
Directory of Open Access Journals (Sweden)
Wang Zhongyu
2014-12-01
Full Text Available For random vibration of airborne platform, the accurate evaluation is a key indicator to ensure normal operation of airborne equipment in flight. However, only limited power spectral density (PSD data can be obtained at the stage of flight test. Thus, those conventional evaluation methods cannot be employed when the distribution characteristics and priori information are unknown. In this paper, the fuzzy norm method (FNM is proposed which combines the advantages of fuzzy theory and norm theory. The proposed method can deeply dig system information from limited data, which probability distribution is not taken into account. Firstly, the FNM is employed to evaluate variable interval and expanded uncertainty from limited PSD data, and the performance of FNM is demonstrated by confidence level, reliability and computing accuracy of expanded uncertainty. In addition, the optimal fuzzy parameters are discussed to meet the requirements of aviation standards and metrological practice. Finally, computer simulation is used to prove the adaptability of FNM. Compared with statistical methods, FNM has superiority for evaluating expanded uncertainty from limited data. The results show that the reliability of calculation and evaluation is superior to 95%.
Vibration-Based Adaptive Novelty Detection Method for Monitoring Faults in a Kinematic Chain
Directory of Open Access Journals (Sweden)
Jesus Adolfo Cariño-Corrales
2016-01-01
Full Text Available This paper presents an adaptive novelty detection methodology applied to a kinematic chain for the monitoring of faults. The proposed approach has the premise that only information of the healthy operation of the machine is initially available and fault scenarios will eventually develop. This approach aims to cover some of the challenges presented when condition monitoring is applied under a continuous learning framework. The structure of the method is divided into two recursive stages: first, an offline stage for initialization and retraining of the feature reduction and novelty detection modules and, second, an online monitoring stage to continuously assess the condition of the machine. Contrary to classical static feature reduction approaches, the proposed method reformulates the features by employing first a Laplacian Score ranking and then the Fisher Score ranking for retraining. The proposed methodology is validated experimentally by monitoring the vibration measurements of a kinematic chain driven by an induction motor. Two faults are induced in the motor to validate the method performance to detect anomalies and adapt the feature reduction and novelty detection modules to the new information. The obtained results show the advantages of employing an adaptive approach for novelty detection and feature reduction making the proposed method suitable for industrial machinery diagnosis applications.
Cao, Hongrui; Niu, Linkai; He, Zhengjia
2012-01-01
Bearing defects are one of the most important mechanical sources for vibration and noise generation in machine tool spindles. In this study, an integrated finite element (FE) model is proposed to predict the vibration responses of a spindle bearing system with localized bearing defects and then the sensor placement for better detection of bearing faults is optimized. A nonlinear bearing model is developed based on Jones' bearing theory, while the drawbar, shaft and housing are modeled as Timoshenko's beam. The bearing model is then integrated into the FE model of drawbar/shaft/housing by assembling equations of motion. The Newmark time integration method is used to solve the vibration responses numerically. The FE model of the spindle-bearing system was verified by conducting dynamic tests. Then, the localized bearing defects were modeled and vibration responses generated by the outer ring defect were simulated as an illustration. The optimization scheme of the sensor placement was carried out on the test spindle. The results proved that, the optimal sensor placement depends on the vibration modes under different boundary conditions and the transfer path between the excitation and the response. PMID:23012514
Borgbjerg, Jens; Bøgsted, Martin; Lindholt, Jes S; Behr-Rasmussen, Carsten; Hørlyck, Arne; Frøkjær, Jens B
2018-02-01
Controversy exists regarding optimal caliper placement in ultrasound assessment of maximum abdominal aortic diameter. This study aimed primarily to determine reproducibility of caliper placement in relation to the aortic wall with the three principal methods: leading to leading edge (LTL), inner to inner edge (ITI), and outer to outer edge (OTO). The secondary aim was to assess the mean difference between the OTO, ITI, and LTL diameters and estimate the impact of using either of these methods on abdominal aortic aneurysm (AAA) prevalence in a screening program. Radiologists (n=18) assessed the maximum antero-posterior abdominal aortic diameter by completing repeated caliper placements with the OTO, LTL, and ITI methods on 50 still abdominal aortic images obtained from an AAA screening program. Inter-observer reproducibility was calculated as the limit of agreement with the mean (LoA), which represents expected deviation of a single observer from the mean of all observers. Intra-observer reproducibility was assessed averaging the LoA for each observer with their repeated measurements. Based on data from an AAA screening trial and the estimated mean differences between the three principal methods, AAA prevalence was estimated using each of the methods. The inter-observer LoA of the OTO, ITI, and LTL was 2.6, 1.9, and 1.9 mm, whereas the intra-observer LoA was 2.0, 1.6, and 1.5 mm, respectively. Mean differences of 5.0 mm were found between OTO and ITI measurements, 2.6 mm between OTO and LTL measurements, and 2.4 mm between LTL and ITI measurements. The prevalence of AAA almost doubled using OTO instead of ITI, while the difference between ITI and LTL was minor (3.3% vs. 4.0% AAA). The study shows superior reproducibility of LTL and ITI compared with the OTO method of caliper placement in ultrasound determination of maximum abdominal aortic diameter, and the choice of caliper placement method significantly affects the prevalence of AAAs in screening programs
International Nuclear Information System (INIS)
Fumagalli, Debora; Gavin, Patrick G; Taniyama, Yusuke; Kim, Seung-Il; Choi, Hyun-Joo; Paik, Soonmyung; Pogue-Geile, Katherine L
2010-01-01
An increasing number of studies show that genetic markers can aid in refining prognostic information and predicting the benefit from systemic therapy. Our goal was to develop a high throughput, cost-effective and simple methodology for the detection of clinically relevant hot spot mutations in colon cancer. The Maldi-Tof mass spectrometry platform and OncoCarta panel from Sequenom were used to profile 239 colon cancers and 39 metastatic lymph nodes from NSABP clinical trial C-07 utilizing routinely processed FFPET (formalin-fixed paraffin-embedded tissue). Among the 238 common hot-spot cancer mutations in 19 genes interrogated by the OncoCarta panel, mutations were detected in 7 different genes at 26 different nucleotide positions in our colon cancer samples. Twenty-four assays that detected mutations in more than 1% of the samples were reconfigured into a new multiplexed panel, termed here as ColoCarta. Mutation profiling was repeated on 32 mutant samples using ColoCarta and the results were identical to results with OncoCarta, demonstrating that this methodology was reproducible. Further evidence demonstrating the validity of the data was the fact that the mutation frequencies of the most common colon cancer mutations were similar to the COSMIC (Catalog of Somatic Mutations in Cancer) database. The frequencies were 43.5% for KRAS, 20.1% for PIK3CA, and 12.1% for BRAF. In addition, infrequent mutations in NRAS, AKT1, ABL1, and MET were detected. Mutation profiling of metastatic lymph nodes and their corresponding primary tumors showed that they were 89.7% concordant. All mutations found in the lymph nodes were also found in the corresponding primary tumors, but in 4 cases a mutation was present in the primary tumor only. This study describes a high throughput technology that can be used to interrogate DNAs isolated from routinely processed FFPET and identifies the specific mutations that are common to colon cancer. The development of this technology and the Colo
Multi-sensor information fusion method for vibration fault diagnosis of rolling bearing
Jiao, Jing; Yue, Jianhai; Pei, Di
2017-10-01
Bearing is a key element in high-speed electric multiple unit (EMU) and any defect of it can cause huge malfunctioning of EMU under high operation speed. This paper presents a new method for bearing fault diagnosis based on least square support vector machine (LS-SVM) in feature-level fusion and Dempster-Shafer (D-S) evidence theory in decision-level fusion which were used to solve the problems about low detection accuracy, difficulty in extracting sensitive characteristics and unstable diagnosis system of single-sensor in rolling bearing fault diagnosis. Wavelet de-nosing technique was used for removing the signal noises. LS-SVM was used to make pattern recognition of the bearing vibration signal, and then fusion process was made according to the D-S evidence theory, so as to realize recognition of bearing fault. The results indicated that the data fusion method improved the performance of the intelligent approach in rolling bearing fault detection significantly. Moreover, the results showed that this method can efficiently improve the accuracy of fault diagnosis.
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.
Yu, Zhi-wu; Mao, Jian-feng; Guo, Feng-qi; Guo, Wei
2016-03-01
Rail irregularity is one of the main sources causing train-bridge random vibration. A new random vibration theory for the coupled train-bridge systems is proposed in this paper. First, number theory method (NTM) with 2N-dimensional vectors for the stochastic harmonic function (SHF) of rail irregularity power spectrum density was adopted to determine the representative points of spatial frequencies and phases to generate the random rail irregularity samples, and the non-stationary rail irregularity samples were modulated with the slowly varying function. Second, the probability density evolution method (PDEM) was employed to calculate the random dynamic vibration of the three-dimensional (3D) train-bridge system by a program compiled on the MATLAB® software platform. Eventually, the Newmark-β integration method and double edge difference method of total variation diminishing (TVD) format were adopted to obtain the mean value curve, the standard deviation curve and the time-history probability density information of responses. A case study was presented in which the ICE-3 train travels on a three-span simply-supported high-speed railway bridge with excitation of random rail irregularity. The results showed that compared to the Monte Carlo simulation, the PDEM has higher computational efficiency for the same accuracy, i.e., an improvement by 1-2 orders of magnitude. Additionally, the influences of rail irregularity and train speed on the random vibration of the coupled train-bridge system were discussed.
Gronbech Jorgensen, Martin; Andersen, Stig; Ryg, Jesper; Masud, Tahir
2015-01-01
Portable, low-cost, objective and reproducible assessment of muscle strength in the lower limbs is important as it allows clinicians to precisly track progression of patients undergoing rehabilitation. The Nintendo Wii Balance Board (WBB) is portable, inexpensive, durable, available worldwide, and may serve the above function. The purpose of the study was to evaluate (1) reproducibility and (2) concurrent validity of the WBB for measuring isometric muscle strength in the lower limb. A custom hardware and software was developed to utilize the WBB for assessment of isometric muscle strength. Thirty older adults (69.0 ± 4.2 years of age) were studied on two separate occasions on both the WBB and a stationary isometric dynamometer (SID). On each occasion, three recordings were obtained from each device. For the first recording, means and maximum values were used for further analysis. The test-retest reproducibility was examined using intraclass correlation coefficients (ICC), Standard Error of Measurement (SEM), and limits of agreement (LOA). Bland-Altman plots (BAP) and ICC's were used to explore concurrent validity. No systematic difference between test-retest was detected for the WBB. ICC within-device were between 0.90 and 0.96 and between-devices were from 0.80 to 0.84. SEM ranged for the WBB from 9.7 to 13.9%, and for the SID from 11.9 to 13.1%. LOA ranged for the WBB from 20.3 to 28.7% and for the SID from 24.2 to 26.6%. The BAP showed no relationship between the difference and the mean. A high relative and an acceptable absolute reproducibility combined with a good validity was found for the novel method using the WBB for measuring isometric lower limb strength in older adults. Further research using the WBB for assessing lower limb strength should be conducted in different study-populations.
Directory of Open Access Journals (Sweden)
Martin Gronbech Jorgensen
Full Text Available Portable, low-cost, objective and reproducible assessment of muscle strength in the lower limbs is important as it allows clinicians to precisly track progression of patients undergoing rehabilitation. The Nintendo Wii Balance Board (WBB is portable, inexpensive, durable, available worldwide, and may serve the above function.The purpose of the study was to evaluate (1 reproducibility and (2 concurrent validity of the WBB for measuring isometric muscle strength in the lower limb.A custom hardware and software was developed to utilize the WBB for assessment of isometric muscle strength. Thirty older adults (69.0 ± 4.2 years of age were studied on two separate occasions on both the WBB and a stationary isometric dynamometer (SID. On each occasion, three recordings were obtained from each device. For the first recording, means and maximum values were used for further analysis. The test-retest reproducibility was examined using intraclass correlation coefficients (ICC, Standard Error of Measurement (SEM, and limits of agreement (LOA. Bland-Altman plots (BAP and ICC's were used to explore concurrent validity.No systematic difference between test-retest was detected for the WBB. ICC within-device were between 0.90 and 0.96 and between-devices were from 0.80 to 0.84. SEM ranged for the WBB from 9.7 to 13.9%, and for the SID from 11.9 to 13.1%. LOA ranged for the WBB from 20.3 to 28.7% and for the SID from 24.2 to 26.6%. The BAP showed no relationship between the difference and the mean.A high relative and an acceptable absolute reproducibility combined with a good validity was found for the novel method using the WBB for measuring isometric lower limb strength in older adults. Further research using the WBB for assessing lower limb strength should be conducted in different study-populations.
Koprowski, Robert; Ambrósio, Renato
2015-11-01
One of the current methods for measuring intraocular pressure is the air-puff method. A tonometer which uses this method is the Corvis device. With the ultra-high-speed (UHS) Scheimpflug camera, it is also possible to observe corneal deformation during measurement. The use of modern image analysis and processing methods allows for analysis of higher harmonics of corneal deflection above 100 Hz. 493 eyes of healthy subjects and 279 eyes of patients with keratoconus were used in the measurements. For each eye, 140 corneal deformation images were recorded during intraocular pressure measurement. Each image was recorded every 230 µs and had a resolution of 200 × 576 pixels. A new, original algorithm for image analysis and processing has been proposed. It enables to separate the eyeball reaction as well as low-frequency and high-frequency corneal deformations from the eye response to an air puff. Furthermore, a method for classification of healthy subjects and patients with keratoconus based on decision trees has been proposed. The obtained results confirm the possibility to distinguish between patients with keratoconus and healthy subjects. The features used in this classification are directly related to corneal vibrations. They are only available in the proposed software and provide specificity of 98%, sensitivity-85%, and accuracy-92%. This confirms the usefulness of the proposed method in this type of classification that uses corneal vibrations during intraocular pressure measurement with the Corvis tonometer. With the new proposed algorithm for image analysis and processing allowing for the separation of individual features from a corneal deformation image, it is possible to: automatically measure corneal vibrations in a few characteristic points of the cornea, obtain fully repeatable measurement of vibrations for the same registered sequence of images and measure vibration parameters for large inter-individual variability in patients. Copyright © 2015 Elsevier
Toyokawa, Masahiro; Kimura, Keigo; Nishi, Isao; Sunada, Atsuko; Ueda, Akiko; Sakata, Tomomi; Asari, Seishi
2013-01-01
Recently, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) has been challenged for the identification of Nocardia species. However, the standard ethanol-formic acid extraction alone is insufficient in allowing the membrane proteins of Nocardia species to be ionized by the matrix. We therefore aimed to establish our new extraction method for the MALDI-TOF MS-based identification of Nocardia species isolates. Our modified extraction procedure is through dissociation in 0.5% Tween-20 followed by bacterial heat-inactivation, mechanical breaking of the cell wall by acid-washed glass beads and protein extraction with formic acid and acetonitrile. As reference methods for species identification, full-length 16S rRNA gene sequencing and some phenotypical tests were used. In a first step, we made our own Nocardia database by analyzing 13 strains (13 different species including N. elegans, N. otitidiscaviarum, N. asiatica, N. abscessus, N. brasiliensis, N. thailandica, N. farcinica, N. nova, N. mikamii, N. cyriacigeorgica, N. asteroids, Nocardiopsis alba, and Micromonospora sp.) and registered to the MALDI BioTyper database. Then we established our database. The analysis of 12 challenge strains using the our database gave a 100% correct identification, including 8 strains identified to the species level and 4 strains to the genus level (N. elegans, N. nova, N. farcinica, Micromonospora sp.) according to the manufacture's log score specifications. In the estimation of reproducibility of our method intended for 4 strains, both within-run and between-run reproducibility were excellent. These data indicates that our method for rapid identification of Nocardia species is with reliability, reproducibility and cost effective.
Bian, Wei; Li, Yan; Crane, Jason C; Nelson, Sarah J
2018-02-01
To implement a fully automated atlas-based method for prescribing 3D PRESS MR spectroscopic imaging (MRSI). The PRESS selected volume and outer-volume suppression bands were predefined on the MNI152 standard template image. The template image was aligned to the subject T 1 -weighted image during a scan, and the resulting transformation was then applied to the predefined prescription. To evaluate the method, H-1 MRSI data were obtained in repeat scan sessions from 20 healthy volunteers. In each session, datasets were acquired twice without repositioning. The overlap ratio of the prescribed volume in the two sessions was calculated and the reproducibility of inter- and intrasession metabolite peak height and area ratios was measured by the coefficient of variation (CoV). The CoVs from intra- and intersession were compared by a paired t-test. The average overlap ratio of the automatically prescribed selection volumes between two sessions was 97.8%. The average voxel-based intersession CoVs were less than 0.124 and 0.163 for peak height and area ratios, respectively. Paired t-test showed no significant difference between the intra- and intersession CoVs. The proposed method provides a time efficient method to prescribe 3D PRESS MRSI with reproducible imaging positioning and metabolite measurements. Magn Reson Med 79:636-642, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.
CFD Simulation of Vortex Induced Vibration for FRP Composite Riser with Different Modeling Methods
Directory of Open Access Journals (Sweden)
Chunguang Wang
2018-04-01
Full Text Available Steel risers are widely used in offshore oil and gas industry. However, the production capacity and depths are limited due to their extreme weight and poor fatigue and corrosion resistance. Nowadays, it is confirmed that fiber reinforced polymer (FRP composite risers have apparent advantages over steel risers. However, the study of vortex induced vibration (VIV for composite risers is rarely involved. Three different risers (one steel riser and two composite risers were compared for their VIV characteristics. The effects of 2D and 3D models and fluid–structure interaction (FSI were considered. The models of composite risers are established by effective modulus method (EMM and layered-structure method (LSM. It is found that 2D model are only suitable for ideal condition, while, for real situation, 3D model with FSI has to be considered. The results show that the displacements of the FRP composite risers are significantly larger than those of the steel riser, while the stresses are reversed. In addition, the distributions of the displacements and stresses depend on the geometries, material properties, top-tension force, constraints, etc. In addition, it is obvious that EMM are suitable to study the global working condition while LSM can be utilized to obtain the results in every single composite layer.
Ganguli, R.
2002-11-01
An aeroelastic analysis based on finite elements in space and time is used to model the helicopter rotor in forward flight. The rotor blade is represented as an elastic cantilever beam undergoing flap and lag bending, elastic torsion and axial deformations. The objective of the improved design is to reduce vibratory loads at the rotor hub that are the main source of helicopter vibration. Constraints are imposed on aeroelastic stability, and move limits are imposed on the blade elastic stiffness design variables. Using the aeroelastic analysis, response surface approximations are constructed for the objective function (vibratory hub loads). It is found that second order polynomial response surfaces constructed using the central composite design of the theory of design of experiments adequately represents the aeroelastic model in the vicinity of the baseline design. Optimization results show a reduction in the objective function of about 30 per cent. A key accomplishment of this paper is the decoupling of the analysis problem and the optimization problems using response surface methods, which should encourage the use of optimization methods by the helicopter industry.
Acute Effect of Lower-Body Vibration as a Recovery Method After Fatiguing Exercise
Directory of Open Access Journals (Sweden)
Svetlana Nepocatych
2015-09-01
Full Text Available The purpose of this study was to compare three recovery methods: control (CON, lower-body vibration (LBV and LBV+ local muscle cooling (LBVC on lower-body performance, perceived recovery, and muscle soreness. Physically active male volunteers (n=8 in a repeated-measures, counterbalanced design, completed three sets of squats to fatigue, each recovery treatment, and two Wingate Anaerobic Tests. Rating of perceived exertion (RPE, and heart rate (HR were measured after fatiguing exercise, recovery treatment and Wingate Anaerobic tests. Peak and mean power, fatigue index, Delayed Onset Muscle Soreness (DOMS, and comfort levels were compared between each treatment. In Wingate 1, no significant differences (p=0.42 were found among CON, LBV, or LBVC regarding peak power (1119±239, 1097±225, and 1146±260 W, respectively, mean power (p=0.32, or fatigue index (p=0.47. In Wingate 2, no significant (p=0.17 differences were found among CON, LBV, or LBVC regarding peak power (1042±228, 1078±233, and 1110±268 W, respectively, mean power (p=0.38, or fatigue index (p=0.15. A significantly better (p=0.01 perceived recovery was observed after LBV (6±1 and LBVC (6±1 compared to CON (4±1. The study findings support psychological but not performance enhancing benefits after the use of LBV and LBVC as recovery methods.
International Nuclear Information System (INIS)
Kann, Frank van; Winterflood, John
2005-01-01
A simple but powerful method is presented for calibrating geophones, seismometers, and other inertial vibration sensors, including passive accelerometers. The method requires no cumbersome or expensive fixtures such as shaker platforms and can be performed using a standard instrument commonly available in the field. An absolute calibration is obtained using the reciprocity property of the device, based on the standard mathematical model for such inertial sensors. It requires only simple electrical measurement of the impedance of the sensor as a function of frequency to determine the parameters of the model and hence the sensitivity function. The method is particularly convenient if one of these parameters, namely the suspended mass is known. In this case, no additional mechanical apparatus is required and only a single set of impedance measurements yields the desired calibration function. Moreover, this measurement can be made with the device in situ. However, the novel and most powerful aspect of the method is its ability to accurately determine the effective suspended mass. For this, the impedance measurement is made with the device hanging from a simple spring or flexible cord (depending on the orientation of its sensitive axis). To complete the calibration, the device is weighed to determine its total mass. All the required calibration parameters, including the suspended mass, are then determined from a least-squares fit to the impedance as a function of frequency. A demonstration using both a 4.5 Hz geophone and a 1 Hz seismometer shows that the method can yield accurate absolute calibrations with an error of 0.1% or better, assuming no a priori knowledge of any parameters
Handbook Of Noise And Vibration
International Nuclear Information System (INIS)
1995-12-01
This book is about noise and vibration. The first chapter has explanations of noise such as basic of sound, influence of noise, assessment of noise, measurement of prevention of noise and technology, case of noise measurement and soundproof. The second chapter describes vibration with outline, theory of vibration, interpretation of vibration, measurement for reduction of vibration, case of design of protection against vibration. It deals with related regulation and method of measurement.
Ilahi, Omer A; Mansfield, David J; Urrea, Luis H; Qadeer, Ali A
2014-10-01
To assess interobserver and intraobserver agreement of estimating anterior cruciate ligament (ACL) femoral tunnel positioning arthroscopically using circular and linear (noncircular) estimation methods and to determine whether overlay template visual aids improve agreement. Standardized intraoperative pictures of femoral tunnel pilot holes (taken with a 30° arthroscope through an anterolateral portal at 90° of knee flexion with horizontal being parallel to the tibial surface) in 27 patients undergoing single-bundle ACL reconstruction were presented to 3 fellowship-trained arthroscopists on 2 separate occasions. On both viewings, each surgeon estimated the femoral tunnel pilot hole location to the nearest half-hour mark using a whole clock face and half clock face, to the nearest 15° using a whole compass and half compass, in the top or bottom half of a linear quadrant, and in the top or bottom half of a linear trisector. Evaluations were performed first without and then with an overlay template of each estimation method. The average difference among reviewers was quite similar for all 4 circular methods with the use of visual aids. Without overlay template visual aids, pair-wise κ statistic values for interobserver agreement ranged from -0.14 to 0.56 for the whole clock face and from 0.16 to 0.42 for the half clock face. With overlay visual guides, interobserver agreement ranged from 0.29 to 0.63 for the whole clock face and from 0.17 to 0.66 for the half clock face. The quadrant method's interobserver agreement ranged from 0.22 to 0.60, and that of the trisection method ranged from 0.17 to 0.57. Neither linear estimation method's reliability uniformly improved with the use of overlay templates. Intraobserver agreement without overlay templates ranged from 0.17 to 0.49 for the whole clock face, 0.11 to 0.47 for the half clock face, 0.01 to 0.66 for the quadrant method, and 0.20 to 0.57 for the trisection method. Use of overlay templates did not uniformly
Vibration reduction methods and techniques for rotorcraft utilizing on-blade active control, Phase I
National Aeronautics and Space Administration — Rotor blades adapted for vibration control have the added benefit of extended blade and rotor life, as well as improved passenger comfort. Approaches that have been...
Umesh P. Agarwal; Rajai Atalla
2010-01-01
Vibrational spectroscopy is an important tool in modern chemistry. In the past two decades, thanks to significant improvements in instrumentation and the development of new interpretive tools, it has become increasingly important for studies of lignin. This chapter presents the three important instrumental methods-Raman spectroscopy, infrared (IR) spectroscopy, and...
Reliability versus reproducibility
International Nuclear Information System (INIS)
Lautzenheiser, C.E.
1976-01-01
Defect detection and reproducibility of results are two separate but closely related subjects. It is axiomatic that a defect must be detected from examination to examination or reproducibility of results is very poor. On the other hand, a defect can be detected on each of subsequent examinations for higher reliability and still have poor reproducibility of results
Energy Technology Data Exchange (ETDEWEB)
Robey, Robert W. [Los Alamos National Laboratory
2016-06-27
The purpose of this presentation is to consider issues of reproducibility, specifically it determines whether bitwise reproducible computation is possible, if computational research in DOE improves its publication process, and if reproducible results can be achieved apart from the peer review process?
Energy Technology Data Exchange (ETDEWEB)
Geng, Yanquan [The State Key Laboratory of Robotics and Systems, Robotics Institute, Harbin Institute of Technology, Harbin, Heilongjiang 150080 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001 (China); Yan, Yongda, E-mail: yanyongda@hit.edu.cn [The State Key Laboratory of Robotics and Systems, Robotics Institute, Harbin Institute of Technology, Harbin, Heilongjiang 150080 (China); Center for Precision Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001 (China); Zhuang, Yun; Hu, Zhenjiang [Center for Precision Engineering, Harbin Institute of Technology, Harbin, Heilongjiang 150001 (China)
2015-11-30
Graphical abstract: - Highlights: • The comparison of three different atomic force microscope (AFM) tip-based material processing techniques to generate nano-grooves on polymethylmethacrylate (PMMA) thin film is presented. • The machined depths of the nano-grooves machined by these three methods are analyzed. • Nano-groove with the machined depth closed to the thickness of the thin-film resist is achieved. - Abstract: This study proposes two atomic force microscope (AFM) tip-based direct nanoscratching methods including single-pass scratching and multi-pass scratching compared with a vibration-assisted scratching method to fabricate nano-grooves on the surface of the polymethylmethacrylate (PMMA) thin-film resist. In order to protect the AFM tip from wearing and optimize the subsequent etching process, the machined depth is expected slightly less than the PMMA thickness to prevent the tip directly contacting with the silicon substrate and obtain better process results. First, single-pass scratching tests are performed on films with different thickness employing varied normal loads. Results show that the machined depths of the grooves cannot be obtained slightly less than the thickness of the film very easily when scratching with single-pass method, 50–120 nm in the present study, which may not be very suitable for the following etching process. Multi-pass and vibration-assisted methods are then utilized to solve this limitation of the machined depth in single-pass process. The machined depths using the multi-pass method are dependent on scratching times and the applied normal loads. Moreover, the depth closed to the thickness of the film can be obtained by enlarging the number of the scratching cycles. However, with a longer scratching time, large tip wear can be found. For vibration assisted method, the machined depths are controlled by the vibration amplitude and the applied normal load. With the vibration in z direction increasing, the machined depth can
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
Shen, Tonghao; Su, Neil Qiang; Wu, Anan; Xu, Xin
2014-03-05
In this work, we first review the perturbative treatment of an oscillator with cubic anharmonicity. It is shown that there is a quantum-classical correspondence in terms of mean displacement, mean-squared displacement, and the corresponding variance in the first-order perturbation theory, provided that the amplitude of the classical oscillator is fixed at the zeroth-order energy of quantum mechanics EQM (0). This correspondence condition is realized by proposing the extended Langevin dynamics (XLD), where the key is to construct a proper driving force. It is assumed that the driving force adopts a simple harmonic form with its amplitude chosen according to EQM (0), while the driving frequency chosen as the harmonic frequency. The latter can be improved by using the natural frequency of the system in response to the potential if its anharmonicity is strong. By comparing to the accurate numeric results from discrete variable representation calculations for a set of diatomic species, it is shown that the present method is able to capture the large part of anharmonicity, being competitive with the wave function-based vibrational second-order perturbation theory, for the whole frequency range from ∼4400 cm(-1) (H2 ) to ∼160 cm(-1) (Na2 ). XLD shows a substantial improvement over the classical molecular dynamics which ceases to work for hard mode when zero-point energy effects are significant. Copyright © 2013 Wiley Periodicals, Inc.
Ye, Shuji; Wei, Feng; Li, Hongchun; Tian, Kangzhen; Luo, Yi
2013-01-01
In situ and real-time characterization of molecular structures and orientation of proteins at interfaces is essential to understand the nature of interfacial protein interaction. Such work will undoubtedly provide important clues to control biointerface in a desired manner. Sum frequency generation vibrational spectroscopy (SFG-VS) has been demonstrated to be a powerful technique to study the interfacial structures and interactions at the molecular level. This paper first systematically introduced the methods for the calculation of the Raman polarizability tensor, infrared transition dipole moment, and SFG molecular hyperpolarizability tensor elements of proteins/peptides with the secondary structures of α-helix, 310-helix, antiparallel β-sheet, and parallel β-sheet, as well as the methodology to determine the orientation of interfacial protein secondary structures using SFG amide I spectra. After that, recent progresses on the determination of protein structure and orientation at different interfaces by SFG-VS were then reviewed, which provides a molecular-level understanding of the structures and interactions of interfacial proteins, specially understanding the nature of driving force behind such interactions. Although this review has focused on analysis of amide I spectra, it will be expected to offer a basic idea for the spectral analysis of amide III SFG signals and other complicated molecular systems such as RNA and DNA. Copyright © 2013 Elsevier Inc. All rights reserved.
Designing a hand rest tremor dynamic vibration absorber using H{sub 2} optimization method
Energy Technology Data Exchange (ETDEWEB)
Rahnavard, Mostafa; Dizaji, Ahmad F. [Tehran University, Tehran (Iran, Islamic Republic of); Hashemi, Mojtaba [Amirkabir University, Tehran (Iran, Islamic Republic of); Faramand, Farzam [Sharif University, Tehran (Iran, Islamic Republic of)
2014-05-15
An optimal single DOF dynamic absorber is presented. A tremor has a random nature and then the system is subjected to a random excitation instead of a sinusoidal one; so the H{sub 2} optimization criterion is probably more desirable than the popular H{sub ∞} optimization method and was implemented in this research. The objective of H{sub 2} optimization criterion is to reduce the total vibration energy of the system for overall frequencies. An objective function, considering the elbow joint angle, θ {sub 2}, tremor suppression as the main goal, was selected. The optimization was done by minimization of this objective function. The optimal system, including the absorber, performance was analyzed in both time and frequency domains. Implementing the optimal absorber, the frequency response amplitude of θ{sub 2} was reduced by more than 98% and 80% at the first and second natural frequencies of the primary system, respectively. A reduction of more than 94% and 78%, was observed for the shoulder joint angle, θ{sub 1}. The objective function also decreased by more than 46%. Then, two types of random inputs were considered. For the first type, θ{sub 1} and θ {sub 2} revealed 60% and 39% reduction in their rms values, whereas for the second type, 33% and 50% decrease was observed.
Designing a hand rest tremor dynamic vibration absorber using H2 optimization method
International Nuclear Information System (INIS)
Rahnavard, Mostafa; Dizaji, Ahmad F.; Hashemi, Mojtaba; Faramand, Farzam
2014-01-01
An optimal single DOF dynamic absorber is presented. A tremor has a random nature and then the system is subjected to a random excitation instead of a sinusoidal one; so the H 2 optimization criterion is probably more desirable than the popular H ∞ optimization method and was implemented in this research. The objective of H 2 optimization criterion is to reduce the total vibration energy of the system for overall frequencies. An objective function, considering the elbow joint angle, θ 2 , tremor suppression as the main goal, was selected. The optimization was done by minimization of this objective function. The optimal system, including the absorber, performance was analyzed in both time and frequency domains. Implementing the optimal absorber, the frequency response amplitude of θ 2 was reduced by more than 98% and 80% at the first and second natural frequencies of the primary system, respectively. A reduction of more than 94% and 78%, was observed for the shoulder joint angle, θ 1 . The objective function also decreased by more than 46%. Then, two types of random inputs were considered. For the first type, θ 1 and θ 2 revealed 60% and 39% reduction in their rms values, whereas for the second type, 33% and 50% decrease was observed.
Contextual sensitivity in scientific reproducibility.
Van Bavel, Jay J; Mende-Siedlecki, Peter; Brady, William J; Reinero, Diego A
2016-06-07
In recent years, scientists have paid increasing attention to reproducibility. For example, the Reproducibility Project, a large-scale replication attempt of 100 studies published in top psychology journals found that only 39% could be unambiguously reproduced. There is a growing consensus among scientists that the lack of reproducibility in psychology and other fields stems from various methodological factors, including low statistical power, researcher's degrees of freedom, and an emphasis on publishing surprising positive results. However, there is a contentious debate about the extent to which failures to reproduce certain results might also reflect contextual differences (often termed "hidden moderators") between the original research and the replication attempt. Although psychologists have found extensive evidence that contextual factors alter behavior, some have argued that context is unlikely to influence the results of direct replications precisely because these studies use the same methods as those used in the original research. To help resolve this debate, we recoded the 100 original studies from the Reproducibility Project on the extent to which the research topic of each study was contextually sensitive. Results suggested that the contextual sensitivity of the research topic was associated with replication success, even after statistically adjusting for several methodological characteristics (e.g., statistical power, effect size). The association between contextual sensitivity and replication success did not differ across psychological subdisciplines. These results suggest that researchers, replicators, and consumers should be mindful of contextual factors that might influence a psychological process. We offer several guidelines for dealing with contextual sensitivity in reproducibility.
Nieuwoudt, Michel K.; Holroyd, Steve E.; McGoverin, Cushla M.; Simpson, M. Cather; Williams, David E.
2017-02-01
Point-of-care diagnostics are of interest in the medical, security and food industry, the latter particularly for screening food adulterated for economic gain. Milk adulteration continues to be a major problem worldwide and different methods to detect fraudulent additives have been investigated for over a century. Laboratory based methods are limited in their application to point-of-collection diagnosis and also require expensive instrumentation, chemicals and skilled technicians. This has encouraged exploration of spectroscopic methods as more rapid and inexpensive alternatives. Raman spectroscopy has excellent potential for screening of milk because of the rich complexity inherent in its signals. The rapid advances in photonic technologies and fabrication methods are enabling increasingly sensitive portable mini-Raman systems to be placed on the market that are both affordable and feasible for both point-of-care and point-of-collection applications. We have developed a powerful spectroscopic method for rapidly screening liquid milk for sucrose and four nitrogen-rich adulterants (dicyandiamide (DCD), ammonium sulphate, melamine, urea), using a combined system: a small, portable Raman spectrometer with focusing fibre optic probe and optimized reflective focusing wells, simply fabricated in aluminium. The reliable sample presentation of this system enabled high reproducibility of 8% RSD (residual standard deviation) within four minutes. Limit of detection intervals for PLS calibrations ranged between 140 - 520 ppm for the four N-rich compounds and between 0.7 - 3.6 % for sucrose. The portability of the system and reliability and reproducibility of this technique opens opportunities for general, reagentless adulteration screening of biological fluids as well as milk, at point-of-collection.
Transfer vibration through spine
Benyovszky, Adam
2012-01-01
Transfer Vibration through Spine Abstract In the bachelor project we deal with the topic of Transfer Vibration through Spine. The problem of TVS is trying to be solved by the critical review method. We analyse some diagnostic methods and methods of treatment based on this principle. Close attention is paid to the method of Transfer Vibration through Spine that is being currently solved by The Research Institute of Thermomechanics in The Czech Academy of Sciences in cooperation with Faculty of...
Jacobs, Michael H G; Schmid-Fetzer, Rainer; van den Berg, Arie P.
2017-01-01
In a previous paper, we showed a technique that simplifies Kieffer’s lattice vibrational method by representing the vibrational density of states with multiple Einstein frequencies. Here, we show that this technique can be applied to construct a thermodynamic database that accurately represents
Directory of Open Access Journals (Sweden)
Muhammad Munawar
2012-01-01
Full Text Available Optimization of surface roughness has been one of the primary objectives in most of the machining operations. Poor control on the desired surface roughness generates non conforming parts and results into increase in cost and loss of productivity due to rework or scrap. Surface roughness value is a result of several process variables among which machine tool condition is one of the significant variables. In this study, experimentation was carried out to investigate the effect of machine tool condition on surface roughness. Variable used to represent machine tool\\'s condition was vibration amplitude. Input parameters used, besides vibration amplitude, were feed rate and insert nose radius. Cutting speed and depth of cut were kept constant. Based on Taguchi orthogonal array, a series of experimentation was designed and performed on AISI 1040 carbon steel bar at default and induced machine tool\\'s vibration amplitudes. ANOVA (Analysis of Variance, revealed that vibration amplitude and feed rate had moderate effect on the surface roughness and insert nose radius had the highest significant effect on the surface roughness. It was also found that a machine tool with low vibration amplitude produced better surface roughness. Insert with larger nose radius produced better surface roughness at low feed rate.
Two methods for damping torsional vibrations in DFIG-based wind generators using power converters
Zhao, Zuyi; Lu, Yupu; Xie, Da; Yu, Songtao; Wu, Wangping
2017-01-01
This paper proposes novel damping control algorithms by using static synchronous compensator (STATCOM) and energy storage system (ESS) to damp torsional vibrations in doubly fed induction generator (DFIG) based wind turbine systems. It first analyses the operating characteristics of STATCOM and ESS for regulating power variations to increase grid voltage stability. Then, new control strategies for STATCOM and ESS are introduced to damp the vibrations. It is followed by illustration of their effectiveness to damp the drive train torsional vibrations of wind turbines, which can be caused by grid disturbances, such as voltage sags and frequency fluctuations. Results suggest that STATCOM is a promising technology to mitigate the torsional vibrations caused by grid voltage sags. By contrast, the ESS connected to the point of common coupling (PCC) of wind turbine systems shows even obvious advantages because of its capability of absorbing/releasing both active and reactive power. It can thus be concluded that STATCOM is useful for stabilizing power system voltage fluctuations, and ESS is more effective both in regulating PCC voltage fluctuations and damping torsional vibrations caused by grid voltage frequency fluctuations.
Viswamurthy, S. R.; Ganguli, Ranjan
2007-03-01
This study aims to determine optimal locations of dual trailing-edge flaps to achieve minimum hub vibration levels in a helicopter, while incurring low penalty in terms of required trailing-edge flap control power. An aeroelastic analysis based on finite elements in space and time is used in conjunction with an optimal control algorithm to determine the flap time history for vibration minimization. The reduced hub vibration levels and required flap control power (due to flap motion) are the two objectives considered in this study and the flap locations along the blade are the design variables. It is found that second order polynomial response surfaces based on the central composite design of the theory of design of experiments describe both objectives adequately. Numerical studies for a four-bladed hingeless rotor show that both objectives are more sensitive to outboard flap location compared to the inboard flap location by an order of magnitude. Optimization results show a disjoint Pareto surface between the two objectives. Two interesting design points are obtained. The first design gives 77 percent vibration reduction from baseline conditions (no flap motion) with a 7 percent increase in flap power compared to the initial design. The second design yields 70 percent reduction in hub vibration with a 27 percent reduction in flap power from the initial design.
Directory of Open Access Journals (Sweden)
Tse M Yat
2011-12-01
Full Text Available Abstract Background The methylation of DNA is recognized as a key mechanism in the regulation of genomic stability and evidence for its role in the development of cancer is accumulating. LINE-1 methylation status represents a surrogate measure of genome-wide methylation. Findings Using high resolution melt (HRM curve analysis technology, we have established an in-tube assay that is linear (r > 0.9986 with a high amplification efficiency (90-105%, capable of discriminating between partcipant samples with small differences in methylation, and suitable for quantifying a wide range of LINE-1 methylation levels (0-100%--including the biologically relevant range of 50-90% expected in human DNA. We have optimized this procedure to perform using 2 μg of starting DNA and 2 ng of bisulfite-converted DNA for each PCR reaction. Intra- and inter-assay coefficients of variation were 1.44% and 0.49%, respectively, supporting the high reproducibility and precision of this approach. Conclusions In summary, this is a completely linear, quantitative HRM PCR method developed for the measurement of LINE-1 methylation. This cost-efficient, refined and reproducible assay can be performed using minimal amounts of starting DNA. These features make our assay suitable for high throughput analysis of multiple samples from large population-based studies.
Gika, Helen G; Theodoridis, Georgios A; Earll, Mark; Wilson, Ian D
2012-09-01
An approach to the determination of day-to-day analytical robustness of LC-MS-based methods for global metabolic profiling using a pooled QC sample is presented for the evaluation of metabonomic/metabolomic data. A set of 60 urine samples were repeatedly analyzed on five different days and the day-to-day reproducibility of the data obtained was determined. Multivariate statistical analysis was performed with the aim of evaluating variability and selected peaks were assessed and validated in terms of retention time stability, mass accuracy and intensity. The methodology enables the repeatability/reproducibility of extended analytical runs in large-scale studies to be determined, allowing the elimination of analytical (as opposed to biological) variability, in order to discover true patterns and correlations within the data. The day-to-day variability of the data revealed by this process suggested that, for this particular system, 3 days continuous operation was possible without the need for maintenance and cleaning. Variation was generally based on signal intensity changes over the 7-day period of the study, and was mainly a result of source contamination.
International Nuclear Information System (INIS)
Bonn, M; Ueba, H; Wolf, M
2005-01-01
A generalized theory of frequency- and time-resolved vibrational sum-frequency generation (SFG) spectroscopy of adsorbates at surfaces is presented using the density matrix formalism. Our theoretical treatment is specifically aimed at addressing issues that accompany the relatively novel SFG approach using broadband infrared pulses. The ultrashort duration of these pulses makes them ideally suited for time-resolved investigations, for which we present a complete theoretical treatment. A second key characteristic of these pulses is their large bandwidth and high intensity, which allow for highly non-linear effects, including vibrational ladder climbing of surface vibrations. We derive general expressions relating the density matrix to SFG spectra, and apply these expressions to specific experimental results by solving the coupled optical Bloch equations of the density matrix elements. Thus, we can theoretically reproduce recent experimentally demonstrated hot band SFG spectra using femtosecond broadband infrared excitation of carbon monoxide (CO) on a Ru(001) surface
A Method to Assess Transverse Vibration Energy of Ship Propeller Shaft for Diagnostic Purposes
Directory of Open Access Journals (Sweden)
Korczewski Zbigniew
2017-12-01
Full Text Available The article discusses a key problem of ship propulsion system vibration diagnostics, which concerns assessing this part of mechanical energy transmitted from the main engine to the ship propeller which is dissipated due to propeller shaft vibration. A simplified calculation model is proposed which allows the total energy of the generated torsional vibration to be assessed from the shaft deflection amplitude measured at the mind-span point between the supports. To verify the developed model, pilot tests were performed on the laboratory rotational mechanical system test rig. In those tests, cyclic bending moment was applied to a unified (cylindrical material sample, which modelled, at an appropriate scale, structural and functional properties of a real propeller shaft.
Energy Technology Data Exchange (ETDEWEB)
Zui, H. [Setsunan University, Osaka (Japan). Faculty of Engineering; Shinke, T. [Kobe Technical College, Kobe, Kobe (Japan); Hamazaki, Y. [Kobe Steel, Ltd., Kobe (Japan)
1995-10-21
The vibration method is usually utilized on the measurement of cable tension during construction of cable bridge such as Nielsen bridges or cable stayed bridges. Practical formula for the vibration method previously proposed by authors is often used where bending rigidity is taken into account. These formula, however, have a certain limit of application and do not yield good results when the cable is not slender or not enough mentioned. The practical formula is modified to improve the accuracy and new formulas are made. The new practical formulas are applicable to any cables, regardless of its length and tension in it. The accuracy is confirmed through comparison of the value obtained by practical formulas with measured values and calculated value by F.E.M. 2 refs., 4 figs., 1 tab.
Liu, Xudong; Wang, Xiaorong; Lin, Sihao; Song, Qingkun; Lao, Xiangqian; Yu, Ignatius Tak-Sun
2015-01-01
This study was conducted to assess the reproducibility and validity of a food frequency questionnaire (FFQ) that was developed to assess the overall dietary consumption via dietary pattern method in a rural population in southwest China. A total of 179 participants aged between 40 and 70 years old were included in this study. Participants administered FFQ at baseline (FFQ1) and one year later (FFQ2) to assess the reproducibility. Six 3-day 24-hour recalls (24HRs) were completed between the administrations of two FFQs to determine the validity. Dietary patterns from three separate dietary sources were derived by using principle component factor analysis. Comparisons between dietary pattern scores were made by using Pearson or intraclass correlation coefficient, cross-classification analysis, weighted kappa (κ) statistic and Bland-Altman analysis. The de-attenuated method was adopted to correct the monthly and seasonally variation and the partial correlation analysis was used correct the influence by total energy intake. Two major dietary factors, labeled as prudent pattern and processed food pattern, were identified. The prudent pattern was characterized by higher factor loadings of wheat, rice, fresh vegetables, bean products, nuts, red meat, white meat and fresh eggs; and the processed food pattern was characterized by higher factor loadings of pickled vegetables, preserved vegetables and salted meat. Between Two FFQs, intraclass correlation coefficients were 0.57 for prudent pattern and 0.55 for processed food pattern, partial Pearson correlation coefficients were 0.51 for the prudent pattern and 0.56 for the processed food pattern; weighted κ statistic ranged from 0.45 (for the prudent pattern) to 0.56 (for the processed food pattern). Between FFQs and 24HRs, de-attenuated correlation coefficients ranged from 0.54 to 0.78 for the prudent pattern and from 0.55 to 0.61 for the processed food pattern; partial Pearson correlation coefficients ranged from 0.41 to 0
Directory of Open Access Journals (Sweden)
Xudong Liu
Full Text Available This study was conducted to assess the reproducibility and validity of a food frequency questionnaire (FFQ that was developed to assess the overall dietary consumption via dietary pattern method in a rural population in southwest China.A total of 179 participants aged between 40 and 70 years old were included in this study. Participants administered FFQ at baseline (FFQ1 and one year later (FFQ2 to assess the reproducibility. Six 3-day 24-hour recalls (24HRs were completed between the administrations of two FFQs to determine the validity. Dietary patterns from three separate dietary sources were derived by using principle component factor analysis. Comparisons between dietary pattern scores were made by using Pearson or intraclass correlation coefficient, cross-classification analysis, weighted kappa (κ statistic and Bland-Altman analysis. The de-attenuated method was adopted to correct the monthly and seasonally variation and the partial correlation analysis was used correct the influence by total energy intake.Two major dietary factors, labeled as prudent pattern and processed food pattern, were identified. The prudent pattern was characterized by higher factor loadings of wheat, rice, fresh vegetables, bean products, nuts, red meat, white meat and fresh eggs; and the processed food pattern was characterized by higher factor loadings of pickled vegetables, preserved vegetables and salted meat. Between Two FFQs, intraclass correlation coefficients were 0.57 for prudent pattern and 0.55 for processed food pattern, partial Pearson correlation coefficients were 0.51 for the prudent pattern and 0.56 for the processed food pattern; weighted κ statistic ranged from 0.45 (for the prudent pattern to 0.56 (for the processed food pattern. Between FFQs and 24HRs, de-attenuated correlation coefficients ranged from 0.54 to 0.78 for the prudent pattern and from 0.55 to 0.61 for the processed food pattern; partial Pearson correlation coefficients ranged
Directory of Open Access Journals (Sweden)
Chantal Beekman
Full Text Available Duchenne muscular dystrophy (DMD is characterized by the absence or reduced levels of dystrophin expression on the inner surface of the sarcolemmal membrane of muscle fibers. Clinical development of therapeutic approaches aiming to increase dystrophin levels requires sensitive and reproducible measurement of differences in dystrophin expression in muscle biopsies of treated patients with DMD. This, however, poses a technical challenge due to intra- and inter-donor variance in the occurrence of revertant fibers and low trace dystrophin expression throughout the biopsies. We have developed an immunofluorescence and semi-automated image analysis method that measures the sarcolemmal dystrophin intensity per individual fiber for the entire fiber population in a muscle biopsy. Cross-sections of muscle co-stained for dystrophin and spectrin have been imaged by confocal microscopy, and image analysis was performed using Definiens software. Dystrophin intensity has been measured in the sarcolemmal mask of spectrin for each individual muscle fiber and multiple membrane intensity parameters (mean, maximum, quantiles per fiber were calculated. A histogram can depict the distribution of dystrophin intensities for the fiber population in the biopsy. This method was tested by measuring dystrophin in DMD, Becker muscular dystrophy, and healthy muscle samples. Analysis of duplicate or quadruplicate sections of DMD biopsies on the same or multiple days, by different operators, or using different antibodies, was shown to be objective and reproducible (inter-assay precision, CV 2-17% and intra-assay precision, CV 2-10%. Moreover, the method was sufficiently sensitive to detect consistently small differences in dystrophin between two biopsies from a patient with DMD before and after treatment with an investigational compound.
Numerical methods for analysis of structure and ground vibration from moving loads
DEFF Research Database (Denmark)
Andersen, L.; Nielsen, S.R.K.; Krenk, Steen
2007-01-01
An overview of the main theoretical aspects of finite-element and boundary-element modelling of the response to moving loads is given. The moving loads represent sources of noise and vibration generated by moving vehicles, and the analysis describes the propagation of the disturbances generated i...
New Methods of Noncontact Sensing of Blade Vibrations and Deflections in Turbomachinery
Czech Academy of Sciences Publication Activity Database
Procházka, Pavel; Vaněk, František
2014-01-01
Roč. 63, č. 6 (2014), s. 1583-1592 ISSN 0018-9456 R&D Projects: GA TA ČR TA02020728 Institutional support: RVO:61388998 Keywords : blade vibrations * induction sensors * magnetoresistive (MR) sensors * steam turbines Subject RIV: BI - Acoustics Impact factor: 1.790, year: 2014
DEFF Research Database (Denmark)
2016-01-01
An example of how to use the magni.reproducibility package for storing metadata along with results from a computational experiment. The example is based on simulating the Mandelbrot set.......An example of how to use the magni.reproducibility package for storing metadata along with results from a computational experiment. The example is based on simulating the Mandelbrot set....
Zhou, Zhenhuan; Li, Yuejie; Fan, Junhai; Rong, Dalun; Sui, Guohao; Xu, Chenghui
2018-05-01
A new Hamiltonian-based approach is presented for finding exact solutions for transverse vibrations of double-nanobeam-systems embedded in an elastic medium. The continuum model is established within the frameworks of the symplectic methodology and the nonlocal Euler-Bernoulli and Timoshenko beam beams. The symplectic eigenfunctions are obtained after expressing the governing equations in a Hamiltonian form. Exact frequency equations, vibration modes and displacement amplitudes are obtained by using symplectic eigenfunctions and end conditions. Comparisons with previously published work are presented to illustrate the accuracy and reliability of the proposed method. The comprehensive results for arbitrary boundary conditions could serve as benchmark results for verifying numerically obtained solutions. In addition, a study on the difference between the nonlocal beam and the nonlocal plate is also included.
Directory of Open Access Journals (Sweden)
Xuanlin Peng
2017-11-01
Full Text Available In this paper, a new methodology is proposed to reduce the vortex-induced vibration (VIV and improve the performance of the stay vane in a 200-MW Francis turbine. The process can be divided into two parts. Firstly, a diagnosis method for stay vane vibration based on field experiments and a finite element method (FEM is presented. It is found that the resonance between the Kármán vortex and the stay vane is the main cause for the undesired vibration. Then, we focus on establishing an intelligent optimization model of the stay vane’s trailing edge profile. To this end, an approach combining factorial experiments, extreme learning machine (ELM and particle swarm optimization (PSO is implemented. Three kinds of improved profiles of the stay vane are proposed and compared. Finally, the profile with a Donaldson trailing edge is adopted as the best solution for the stay vane, and verifications such as computational fluid dynamics (CFD simulations, structural analysis and fatigue analysis are performed to validate the optimized geometry.
Vibration of hydraulic machinery
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...
International Nuclear Information System (INIS)
Bayne, Michael; Hicks, Rodney J.; Everitt, Sarah; Fimmell, Natalie
2010-01-01
Purpose: Positron emission tomography/computed tomography (PET/CT) is increasingly used for delineating gross tumor volume (GTV) in non-small-cell lung cancer (NSCLC). The methodology for contouring tumor margins remains controversial. We developed a rigorous visual protocol for contouring GTV that uses all available clinical information and studied its reproducibility in patients from a prospective PET/CT planning trial. Methods and Materials: Planning PET/CT scans from 6 consecutive patients were selected. Six 'observers' (two radiation oncologists, two nuclear medicine physicians, and two radiologists) contoured GTVs for each patient using a predefined protocol and subsequently recontoured 2 patients. For the estimated GTVs and axial distances, least-squares means for each observer and for each case were calculated and compared, using the F test and pairwise t-tests. In five cases, tumor margins were also autocontoured using standardized uptake value (SUV) cutoffs of 2.5 and 3.5 and 40% SUV max . Results: The magnitude of variation between observers was small relative to the mean (coefficient of variation [CV] = 3%), and the total variation (intraclass correlation coefficient [ICC] = 3%). For estimation of superior/inferior (SI), left/right (LR), and anterior/posterior (AP) borders of the GTV, differences between observers were also small (AP, CV = 2%, ICC = 0.4%; LR, CV = 6%, ICC = 2%; SI, CV 4%, ICC = 2%). GTVs autocontoured generated using SUV 2.5, 3.5, and 40% SUV max differed widely in each case. An SUV contour of 2.5 was most closely correlated with the mean GTV defined by the human observers. Conclusions: Observer variation contributed little to total variation in the GTV and axial distances. A visual contouring protocol gave reproducible results for contouring GTV in NSCLC.
Directory of Open Access Journals (Sweden)
Ali Bagherian
2016-01-01
Conclusion: It may be concluded that the cotton-roll vibration method can be more helpful than the routine topical anesthesia in reducing behavioral pain reactions in children during local anesthesia administration.
Directory of Open Access Journals (Sweden)
Mahmoud Bayat
Full Text Available This review features a survey of some recent developments in asymptotic techniques and new developments, which are valid not only for weakly nonlinear equations, but also for strongly ones. Further, the achieved approximate analytical solutions are valid for the whole solution domain. The limitations of traditional perturbation methods are illustrated, various modified perturbation techniques are proposed, and some mathematical tools such as variational theory, homotopy technology, and iteration technique are introduced to over-come the shortcomings.In this review we have applied different powerful analytical methods to solve high nonlinear problems in engineering vibrations. Some patterns are given to illustrate the effectiveness and convenience of the methodologies.
N-propyl nitrate vibrational spectrum analysis using DFT B3LYP quantum-chemical method
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.
Vibration study of a vehicle suspension assembly with the finite element method
Cătălin Marinescu, Gabriel; Castravete, Ştefan-Cristian; Dumitru, Nicolae
2017-10-01
The main steps of the present work represent a methodology of analysing various vibration effects over suspension mechanical parts of a vehicle. A McPherson type suspension from an existing vehicle was created using CAD software. Using the CAD model as input, a finite element model of the suspension assembly was developed. Abaqus finite element analysis software was used to pre-process, solve, and post-process the results. Geometric nonlinearities are included in the model. Severe sources of nonlinearities such us friction and contact are also included in the model. The McPherson spring is modelled as linear spring. The analysis include several steps: preload, modal analysis, the reduction of the model to 200 generalized coordinates, a deterministic external excitation, a random excitation that comes from different types of roads. The vibration data used as an input for the simulation were previously obtained by experimental means. Mathematical expressions used for the simulation were also presented in the paper.
Hao, Hongliang; Xiao, Wen; Chen, Zonghui; Ma, Lan; Pan, Feng
2018-01-01
Heterodyne interferometric vibration metrology is a useful technique for dynamic displacement and velocity measurement as it can provide a synchronous full-field output signal. With the advent of cost effective, high-speed real-time signal processing systems and software, processing of the complex signals encountered in interferometry has become more feasible. However, due to the coherent nature of the laser sources, the sequence of heterodyne interferogram are corrupted by a mixture of coherent speckle and incoherent additive noise, which can severely degrade the accuracy of the demodulated signal and the optical display. In this paper, a new heterodyne interferometric demodulation method by combining auto-correlation analysis and spectral filtering is described leading to an expression for the dynamic displacement and velocity of the object under test that is significantly more accurate in both the amplitude and frequency of the vibrating waveform. We present a mathematical model of the signals obtained from interferograms that contain both vibration information of the measured objects and the noise. A simulation of the signal demodulation process is presented and used to investigate the noise from the system and external factors. The experimental results show excellent agreement with measurements from a commercial Laser Doppler Velocimetry (LDV).
Contextual sensitivity in scientific reproducibility
Van Bavel, Jay J.; Mende-Siedlecki, Peter; Brady, William J.; Reinero, Diego A.
2016-01-01
In recent years, scientists have paid increasing attention to reproducibility. For example, the Reproducibility Project, a large-scale replication attempt of 100 studies published in top psychology journals found that only 39% could be unambiguously reproduced. There is a growing consensus among scientists that the lack of reproducibility in psychology and other fields stems from various methodological factors, including low statistical power, researcher’s degrees of freedom, and an emphasis on publishing surprising positive results. However, there is a contentious debate about the extent to which failures to reproduce certain results might also reflect contextual differences (often termed “hidden moderators”) between the original research and the replication attempt. Although psychologists have found extensive evidence that contextual factors alter behavior, some have argued that context is unlikely to influence the results of direct replications precisely because these studies use the same methods as those used in the original research. To help resolve this debate, we recoded the 100 original studies from the Reproducibility Project on the extent to which the research topic of each study was contextually sensitive. Results suggested that the contextual sensitivity of the research topic was associated with replication success, even after statistically adjusting for several methodological characteristics (e.g., statistical power, effect size). The association between contextual sensitivity and replication success did not differ across psychological subdisciplines. These results suggest that researchers, replicators, and consumers should be mindful of contextual factors that might influence a psychological process. We offer several guidelines for dealing with contextual sensitivity in reproducibility. PMID:27217556
Sanbi, M.; Saadani, R.; Sbai, K.; Rahmoune, M.
2015-01-01
Theoretical and numerical results of the modeling of a smart plate are presented for optimal active vibration control. The smart plate consists of a rectangular aluminum piezocomposite plate modeled in cantilever configuration with surface bonded thermopiezoelectric patches. The patches are symmetrically bonded on top and bottom surfaces. A generic thermopiezoelastic theory for piezocomposite plate is derived, using linear thermopiezoelastic theory and Kirchhoff assumptions. Finite element eq...
Energy Technology Data Exchange (ETDEWEB)
Viswanathan, K. K.; Aziz, Z. A.; Javed, Saira; Yaacob, Y. [Universiti Teknologi Malaysia, Johor Bahru (Malaysia); Pullepu, Babuji [S R M University, Chennai (India)
2015-05-15
Free vibration of symmetric angle-ply laminated truncated conical shell is analyzed to determine the effects of frequency parameter and angular frequencies under different boundary condition, ply angles, different material properties and other parameters. The governing equations of motion for truncated conical shell are obtained in terms of displacement functions. The displacement functions are approximated by cubic and quintic splines resulting into a generalized eigenvalue problem. The parametric studies have been made and discussed.
International Nuclear Information System (INIS)
Viswanathan, K. K.; Aziz, Z. A.; Javed, Saira; Yaacob, Y.; Pullepu, Babuji
2015-01-01
Free vibration of symmetric angle-ply laminated truncated conical shell is analyzed to determine the effects of frequency parameter and angular frequencies under different boundary condition, ply angles, different material properties and other parameters. The governing equations of motion for truncated conical shell are obtained in terms of displacement functions. The displacement functions are approximated by cubic and quintic splines resulting into a generalized eigenvalue problem. The parametric studies have been made and discussed.
METİN, Muzaffer; GÜÇLÜ, Rahmi
2014-01-01
In this study, a conventional PID type fuzzy controller and parameter adaptive fuzzy controller are designed to control vibrations actively of a light rail transport vehicle which modeled as 6 degree-of-freedom system and compared performances of these two controllers. Rail vehicle model consists of a passenger seat and its suspension system, vehicle body, bogie, primary and secondary suspensions and wheels. The similarity between mathematical model and real system is shown by compar...
International Nuclear Information System (INIS)
Razi, Pejman; Esmaeel, Ramadan A; Taheri, Farid
2011-01-01
This paper presents the application of a novel vibration-based technique for detecting fatigue cracks in structures. The method utilizes the empirical mode decomposition method (EMD) to establish an effective energy-based damage index. To investigate the feasibility of the method, fatigue cracks of different sizes were introduced in an aluminum beam subjected to a cyclic load under a three-point bending configuration. The vibration signals corresponding to the healthy and the damaged states of the beam were acquired via piezoceramic sensors. The signals were then processed by the proposed methodology to obtain the damage indices. In addition, for the sake of comparison, the frequency and damping analysis were performed on the test specimen. The results of this study concluded with two major observations. Firstly, the method was highly successful in not only predicting the presence of the fatigue crack, but also in quantifying its progression. Secondly, the proposed energy-based damage index was proved to be superior to the frequency-based methods in terms of sensitivity to the damage detection and quantification. As a result, this technique could be regarded as an efficient non-destructive tool, since it is simple, cost-effective and does not rely on analytical modeling of structures. In addition, the capability of the finite element method (FEM) in mimicking the experiments, and hence for consideration as an effective tool for conducting future parametric studies, was also investigated
Directory of Open Access Journals (Sweden)
Wan-You Li
2014-01-01
Full Text Available A novel hybrid method, which simultaneously possesses the efficiency of Fourier spectral method (FSM and the applicability of the finite element method (FEM, is presented for the vibration analysis of structures with elastic boundary conditions. The FSM, as one type of analytical approaches with excellent convergence and accuracy, is mainly limited to problems with relatively regular geometry. The purpose of the current study is to extend the FSM to problems with irregular geometry via the FEM and attempt to take full advantage of the FSM and the conventional FEM for structural vibration problems. The computational domain of general shape is divided into several subdomains firstly, some of which are represented by the FSM while the rest by the FEM. Then, fictitious springs are introduced for connecting these subdomains. Sufficient details are given to describe the development of such a hybrid method. Numerical examples of a one-dimensional Euler-Bernoulli beam and a two-dimensional rectangular plate show that the present method has good accuracy and efficiency. Further, one irregular-shaped plate which consists of one rectangular plate and one semi-circular plate also demonstrates the capability of the present method applied to irregular structures.
Anharmonicities of coupled β and γ vibrations discussed in a simple model
International Nuclear Information System (INIS)
Piepenbring, R.; Silvestre-Brac, B.; Szymanski, Z.
1984-01-01
The multiphonon method based on β and γ phonons is tested in a simple model allowing an exact solution for a many body fermion system where pairing and quadrupole forces are acting. The properties exhibiting the anharmonicities of the lowest-lying vibrational states of positive parity are nicely reproduced by this method. (orig.)
Anharmonicities of coupled β and γ vibrations discussed in a simple model
International Nuclear Information System (INIS)
Piepenbring, R.; Silvestre-Brac, B.; Szymanski, Z.
1983-11-01
The multiphonon method based on β and γ phonons is tested in a simple model allowing an exact solution for a many body fermion system where pairing and quadrupole forces are acting. The properties exhibiting the anharmonicities of the lowest-lying vibrational states of positive parity are nicely reproduced by this method
Directory of Open Access Journals (Sweden)
Dongyan Shi
2016-01-01
Full Text Available This paper presents free vibration analysis of open and closed shells with arbitrary boundary conditions using a spectro-geometric-Ritz method. In this method, regardless of the boundary conditions, each of the displacement components of open and closed shells is represented simultaneously as a standard Fourier cosine series and several auxiliary functions. The auxiliary functions are introduced to accelerate the convergence of the series expansion and eliminate all the relevant discontinuities with the displacement and its derivatives at the boundaries. The boundary conditions are modeled using the spring stiffness technique. All the expansion coefficients are treated equally and independently as the generalized coordinates and determined using Rayleigh-Ritz method. By using this method, a unified vibration analysis model for the open and closed shells with arbitrary boundary conditions can be established without the need of changing either the equations of motion or the expression of the displacement components. The reliability and accuracy of the proposed method are validated with the FEM results and those from the literature.
Directory of Open Access Journals (Sweden)
Sang-Wook Kang
2016-03-01
Full Text Available A new formulation for the non-dimensional dynamic influence function method, which was developed by the authors, is proposed to efficiently extract eigenvalues and mode shapes of clamped plates with arbitrary shapes. Compared with the finite element and boundary element methods, the non-dimensional dynamic influence function method yields highly accurate solutions in eigenvalue analysis problems of plates and membranes including acoustic cavities. However, the non-dimensional dynamic influence function method requires the uneconomic procedure of calculating the singularity of a system matrix in the frequency range of interest for extracting eigenvalues because it produces a non-algebraic eigenvalue problem. This article describes a new approach that reduces the problem of free vibrations of clamped plates to an algebraic eigenvalue problem, the solution of which is straightforward. The validity and efficiency of the proposed method are illustrated through several numerical examples.
Nguyen Van Do, Vuong
2018-04-01
In this paper, a modified Kirchhoff theory is presented for free vibration analyses of functionally graded material (FGM) plate based on modified radial point interpolation method (RPIM). The shear deformation effects are taken account into modified theory to ignore the locking phenomenon of thin plates. Due to the proposed refined plate theory, the number of independent unknowns reduces one variable and exists with four degrees of freedom per node. The simulated free vibration results employed by the modified RPIM are compared with the other analytical solutions to verify the effectiveness and the accuracy of the developed mesh-free method. Detail parametric studies of the proposed method are then conducted including the effectiveness of thickness ratio, boundary condition and material inhomogeneity on the sample problems of square plates. Results illustrated that the modified mesh-free RPIM can effectively predict the numerical calculation as compared to the exact solutions. The obtained numerical results are indicated that the proposed method are stable and well accurate prediction to evaluate with other published analyses.
International Nuclear Information System (INIS)
Naitoh, Masanori; Uchida, Shunsuke; Koshizuka, Seiichi; Ninokata, Hisashi; Anahara, Naoki; Dosaki, Koji; Katono, Kenichi; Akiyama, Minoru; Saitoh, Hiroaki
2007-01-01
Problems in major components and structural materials in nuclear power plants have often been caused by flow induced vibration, corrosion and their overlapping effects. In order to establish safe and reliable plant operation, it is necessary to predict future problems for structural materials based on combined analyses of flow dynamics and corrosion and to mitigate them before they become serious issues for plant operation. An innovative method for flow induced vibration of structures in two phase flow by combined analyses of three dimensional flow dynamics and structures is to be introduced. (author)
Flux-line response in 2H-NbSe 2 investigated by means of the vibrating superconductor method
D'Anna, G.; André, M.-O.; Benoit, W.; Rodríguez, E.; Rodríguez, D. S.; Luzuriaga, J.; Wasczak, J. V.
1993-12-01
We measure transverse AC losses in the low- and high-amplitude regime of 2H-NbSe 2 single crystals using vibrating superconductor methods. The measurements are sensitive to small deviations of the critical state. The data constitute evidence for a peak effect of the critical current as a function of the temperature in this compound. We construct in the H- T phase diagram the “peak-effect” line which is supposed to mark an abrupt cross-over in the vortex-pinning regime.
A quality control method by ultrasonic vibration energy and diagnosis system at trimming process
International Nuclear Information System (INIS)
Suh, Chang Min; Song, Gil Ho; Pyoun, Young Shik
2007-01-01
In this paper, the characteristics in mechanical properties of ultrasonic cold forging treatment (UCFT) used for the trimming knife and the effects of ultrasonic vibration energy (UVE) into the trimming process on the state of the strip cutting face were studied. And a diagnosis system to quality control for trimming knife and strip cutting face was developed and installed in plant. By the plant application of UCFT, service life of knife was more increased over 100% than that of conventional knife and using the developed diagnosis system, the knife breakage and saw ear have been perfectly detected and quality control of trimming face is effectively obtained
Energy Technology Data Exchange (ETDEWEB)
Burlin, Stenio; Favaro, Larissa Rossini; Bretas, Elisa Almeida Sathler; Taniguchi, Lincoln Seiji; Argollo, Marjorie Costa; Ambrogini Junior, Orlando; D' Ippolito, Giuseppe, E-mail: stenioburlin@gmail.com [Universidade Federal de Sao Paulo (EPM/UNIFESP), Sao Paulo, SP (Brazil). Escola Paulista de Medicina; Loch, Ana Paula [Universidade de Sao Paulo (FM/USP), Sao Paulo, SP (Brazil). Faculdade de Medicina
2017-01-15
Objective: To assess the impact that examiner experience has on the reproducibility and accuracy of computed tomography (CT) enterography in the detection of radiological signs in patients with Crohn's disease. Materials and Methods: This was a retrospective, cross-sectional observational study involving the analysis of CT enterography scans of 20 patients with Crohn's disease. The exams were analyzed independently by two radiologists in their last year of residence (duo I) and by two abdominal imaging specialists (duo II). The interobserver agreement of each pair of examiners in identifying the main radiological signs was calculated with the kappa test. The accuracy of the examiners with less experience was quantified by using the consensus among three experienced examiners as a reference. Results: Duo I and duo II obtained a similar interobserver agreement, with a moderate to good correlation, for mural hyper enhancement, parietal thickening, mural stratification, fat densification, and comb sign (kappa: 0.45 - 0.64). The less experienced examiners showed an accuracy > 80% for all signs, except for lymph nodes and fistula, for which it ranged from 60% to 75%. Conclusion: Less experienced examiners have a tendency to present a level of interobserver agreement similar to that of experienced examiners in evaluating Crohn's disease through CT enterography, as well as showing satisfactory accuracy in identifying most radiological signs of the disease. (author)
Jacobsen, Heiko; Cavallo, Luigi
2011-01-01
phosphanes, while functionals not including dispersion interaction reproduce the experimental trends with reasonable accuracy. In case of the DFT-D functionals, inclusion of a cut-off distance on the dispersive term resolves this issue, and results in a
Testing Reproducibility in Earth Sciences
Church, M. A.; Dudill, A. R.; Frey, P.; Venditti, J. G.
2017-12-01
Reproducibility represents how closely the results of independent tests agree when undertaken using the same materials but different conditions of measurement, such as operator, equipment or laboratory. The concept of reproducibility is fundamental to the scientific method as it prevents the persistence of incorrect or biased results. Yet currently the production of scientific knowledge emphasizes rapid publication of previously unreported findings, a culture that has emerged from pressures related to hiring, publication criteria and funding requirements. Awareness and critique of the disconnect between how scientific research should be undertaken, and how it actually is conducted, has been prominent in biomedicine for over a decade, with the fields of economics and psychology more recently joining the conversation. The purpose of this presentation is to stimulate the conversation in earth sciences where, despite implicit evidence in widely accepted classifications, formal testing of reproducibility is rare.As a formal test of reproducibility, two sets of experiments were undertaken with the same experimental procedure, at the same scale, but in different laboratories. Using narrow, steep flumes and spherical glass beads, grain size sorting was examined by introducing fine sediment of varying size and quantity into a mobile coarse bed. The general setup was identical, including flume width and slope; however, there were some variations in the materials, construction and lab environment. Comparison of the results includes examination of the infiltration profiles, sediment mobility and transport characteristics. The physical phenomena were qualitatively reproduced but not quantitatively replicated. Reproduction of results encourages more robust research and reporting, and facilitates exploration of possible variations in data in various specific contexts. Following the lead of other fields, testing of reproducibility can be incentivized through changes to journal
Energy Technology Data Exchange (ETDEWEB)
Zhou, Shui-Ting; Huang, Hong-Wu [Hunan University, Changsha (China); Chiu, Yi-Jui; Yu, Guo-Fei [Xiamen University of Technology, Xiamen (China); Yang, Chia-Hao [Taipei Chengshih University of Science and Technology, Taipei (China); Jian, Sheng-Rui [I-Shou University, Kaohsiung (China)
2017-02-15
The Assumed mode method (AMM) and Finite element method (FEM) were used. Their results were compared to investigate the coupled shaft-torsion, disk-transverse, and blade-bending vibrations in a flexible-disk rotor system. The blades were grouped with a spring. The flexible-disk rotor system was divided into three modes of coupled vibrations: Shaft-disk-blade, disk-blade, and blade-blade. Two new modes of coupled vibrations were introduced, namely, lacing wires-blade and lacing wires-disk-blade. The patterns of change of the natural frequencies and mode shapes of the system were discussed. The results showed the following: first, mode shapes and natural frequencies varied, and the results of the AMM and FEM differed; second, numerical calculation results showed three influencing factors on natural frequencies, namely, the lacing wire constant, the lacing wire location, and the flexible disk; lastly, the flexible disk could affect the stability of the system as reflected in the effect of the rotational speed.
International Nuclear Information System (INIS)
Zhong, Jianfeng; Zhong, Shuncong; Zhang, Qiukun; Lu, Huancai; Zhuang, Yizhou; Fu, Xinbin
2017-01-01
A non-projection fringe vision measurement system suitable for vibration monitoring was proposed by using the concept of a 2D optical coherence vibration tomography (2D-OCVT) technique. An artificial quasi-interferogram fringe pattern (QIFP), similar to the interferogram of the 2D-OCVT system, was pasted onto the surface of a vibrating structure as a sensor. Image sequences of the QIFP were captured by a high-speed CMOS camera that worked as a detector. It was possible to obtain both the in-plane and out-of-plane vibration simultaneously. The in-plane vibration was obtained by tracking the center of the imaged QIFP using an image cross-correlation method, whilst the out-of-plane vibration was obtained from the changes in period density of the imaged QIFP. The influence of the noise sources from the CMOS image sensor, together with the effect of the imaging distance, the period density of the QIFP and also the key parameters of the fringe density enhanced by the spectrum correction method on the accuracy of the displacement measurement, were investigated by numerical simulations and experiments. Compared with the results from a conventional accelerometer-based measurement system, the proposed method was demonstrated to be an effective and accurate technique for measuring structural vibration without introducing any extra mass from the accelerometer. The significant advantages of this method include its simple installation and real-time dynamic response measurement capability, making the measurement system ideal for the low- and high-frequency vibration monitoring of engineering structures. (paper)
International Nuclear Information System (INIS)
Shin, Young Jae; Hwang, Ki Sup; Yun, Jong Hak
2006-01-01
The main purpose of this paper is to apply Differential Transformation Method(DTM) and Generalized Differential Quadrature Method(GDQM) to vibration analysis of Euler-Bernoulli beam with open cracks on elastic foundation. In this paper the concepts of DTM and GDQM were briefly introduced. The governing equation of motion of the beam with open cracks on elastic foundation is derived. The cracks are modeled by massless substitute spring. The effects of the crack location, size and the foundation constants, on the natural frequencies of the beam, are investigated. Numerical calculations are carried out and compared with previous published results
Preserve specimens for reproducibility
Czech Academy of Sciences Publication Activity Database
Krell, F.-T.; Klimeš, Petr; Rocha, L. A.; Fikáček, M.; Miller, S. E.
2016-01-01
Roč. 539, č. 7628 (2016), s. 168 ISSN 0028-0836 Institutional support: RVO:60077344 Keywords : reproducibility * specimen * biodiversity Subject RIV: EH - Ecology, Behaviour Impact factor: 40.137, year: 2016 http://www.nature.com/nature/journal/v539/n7628/full/539168b.html
Qing, Xinlin (Inventor); Beard, Shawn J. (Inventor); Li, Irene (Inventor)
2013-01-01
Sensors affixed to various such structures, where the sensors can withstand, remain affixed, and operate while undergoing both cryogenic temperatures and high vibrations. In particular, piezoelectric single crystal transducers are utilized, and these sensors are coupled to the structure via a low temperature, heat cured epoxy. This allows the transducers to monitor the structure while the engine is operating, even despite the harsh operating conditions. Aspects of the invention thus allow for real time monitoring and analysis of structures that operate in conditions that previously did not permit such analysis. A further aspect of the invention relates to use of piezoelectric single crystal transducers. In particular, use of such transducers allows the same elements to be used as both sensors and actuators.
System and method for damping vibration in a drill string using a magnetorheological damper
Wassell, Mark Ellsworth; Burgess, Daniel E.; Barbely, Jason R.; Thompson, Fred Lamar
2018-05-22
A system for damping vibration in a drill string can include a magnetorheological fluid valve assembly having a supply of a magnetorheological fluid. A remanent magnetic field is induced in the valve during operation that can be used to provide the magnetic field for operating the valve so as to eliminate the need to energize the coils except temporarily when changing the amount of damping required. The current to be supplied to the coil for inducing a desired magnetic field in the valve is determined based on the limiting hysteresis curve of the valve and the history of the magnetization of the value using a binary search methodology. The history of the magnetization of the valve is expressed as a series of sets of current and it resulting magnetization at which the current experienced a reversal compared to prior values of the current.
Kamarudin, A. F.; Zainal Abidin, M. H.; Mokhatar, S. N.; Daud, M. E.; Ibrahim, A.; Ibrahim, Z.; Noh, M. S. Md
2018-04-01
Natural frequency is the rate at which a body to vibrate or oscillate. Application of ambient vibration (AV) excitation is widely used nowadays as the input motion for building predominant frequency, fo, and ground fundamental frequency, Fo, prediction due to simple, fast, non-destructive, simple handling operation and reliable result. However, it must be emphasized and caution to isolate these frequencies (fo and Fo) from spurious frequencies of site-structure effects especially to low rise building on soft ground deposit. In this study, identification of fo and Fo by using AV measurements were performed on ground and 4-storey primary school reinforced concrete (RC) building at Sekolah Kebangsaan (SK) Sg. Tongkang, Rengit, Johor using 1 Hz of tri-axial seismometer sensor. Overlapping spectra between Fourier Amplitude Spectra (FAS) from and Horizontal to Vertical Spectra Ratio (HVSR) were used to distinguish respective frequencies of building and ground natural frequencies. Three dominant frequencies were identified from the FAS curves at 1.91 Hz, 1.98 Hz and 2.79 Hz in longitudinal (East West-EW), transverse (North South-NS) and vertical (UD) directions. It is expected the building has deformed in translational mode based on the first peak frequency by respective NS and EW components of FAS spectrum. Vertical frequency identified from the horizontal spectrums, might induces to the potential of rocking effect experienced by the school building. Meanwhile, single peak HVSR spectrum at low ground fundamental frequency concentrated at 0.93 Hz indicates to the existence deep contrast of soft deposit. Strong interaction between ground and building at similar frequency (0.93 Hz) observed from the FAS curves on the highest floor has shown the building to behave as a dependent unit against ground response as one rigid mass.
Bagherian, Ali; Sheikhfathollahi, Mahmood
2016-01-01
Topical anesthesia has been widely advocated as an important component of atraumatic administration of intraoral local anesthesia. The aim of this study was to use direct observation of children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia. Forty-eight children participated in this randomized controlled clinical trial. They received two separate inferior alveolar nerve block or primary maxillary molar infiltration injections on contralateral sides of the jaws by both cotton-roll vibration (a combination of topical anesthesia gel, cotton roll, and vibration for physical distraction) and control (routine topical anesthesia) methods. Behavioral pain reactions of children were measured according to the author-developed face, head, foot, hand, trunk, and cry (FHFHTC) scale, resulting in total scores between 0 and 18. The total scores on the FHFHTC scale ranged between 0-5 and 0-10 in the cotton-roll vibration and control methods, respectively. The mean ± standard deviation values of total scores on FHFHTC scale were lower in the cotton-roll vibration method (1.21 ± 1.38) than in control method (2.44 ± 2.18), and this was statistically significant (P anesthesia in reducing behavioral pain reactions in children during local anesthesia administration.
Structural, vibrational, elastic and topological properties of PaN under pressure
DEFF Research Database (Denmark)
Modak, P.; K. Verma, Ashok; Svane, A.
2013-01-01
Electronic, structural, vibrational and elastic properties of PaN have been studied both at ambient and high pressures, using first principles methods with several commonly used parameterizations of the exchange-correlation energy. The generalized gradient approximation (GGA) reproduces the groun...
Energy Technology Data Exchange (ETDEWEB)
Choi, Myung Soo; Yang, Kyong Uk [Chonnam National University, Yeosu (Korea, Republic of); Kondou, Takahiro [Kyushu University, Fukuoka (Japan); Bonkobara, Yasuhiro [University of Miyazaki, Miyazaki (Japan)
2016-03-15
We developed a method for analyzing the free vibration of a structure regarded as a distributed system, by combining the Wittrick-Williams algorithm and the transfer dynamic stiffness coefficient method. A computational algorithm was formulated for analyzing the free vibration of a straight-line beam regarded as a distributed system, to explain the concept of the developed method. To verify the effectiveness of the developed method, the natural frequencies of straight-line beams were computed using the finite element method, transfer matrix method, transfer dynamic stiffness coefficient method, the exact solution, and the developed method. By comparing the computational results of the developed method with those of the other methods, we confirmed that the developed method exhibited superior performance over the other methods in terms of computational accuracy, cost and user convenience.
Directory of Open Access Journals (Sweden)
Laith K. Abbas
2013-01-01
Full Text Available The feasibility of using the transfer matrix method (TMM to compute the natural vibration characteristics of a flexible rocket/satellite launch vehicle is explored theoretically. In the approach to the problem, a nonuniform free-free Timoshenko and Euler-Bernoulli beamlike structure is modeled. A provision is made to take into consideration the effects of shear deformation and rotary inertia. Large thrust-to-weight ratio leads to large axial accelerations that result in an axial inertia load distribution from nose to tail which causes the development of significant compressive forces along the length of the launch vehicle. Therefore, it is important to take into account this effect in the transverse vibration model. Once the transfer matrix of a single component has been obtained, the product of all component matrices composes the matrix of the entire structure. The frequency equation and mode shape are formulated in terms of the elements of the structural matrices. Flight test and analytical results validate the present TMM formulas.
International Nuclear Information System (INIS)
Ji, Hongli; Qiu, Jinhao; Xia, Pinqi; Inman, Daniel
2012-01-01
Modal coupling is an important issue in the analysis and control of structural systems with multi-degrees of freedom (MDOF). In this paper, modal coupling induced by energy conversion in the structural control of an MDOF system using a synchronized switch damping method is investigated theoretically and validated numerically. In the analysis, it is supposed that the voltage on the piezoelectric actuator is switched at the displacement extrema of a given mode. Two types of coupling in energy conversion are considered. The first is whether the switching action based on one mode induces energy conversion of the other modes. The second is whether the vibration of one mode affects the energy conversion of the other modes. The results indicate that the modal coupling in energy conversion is very complicated. In most cases the switching action based on one mode does induce energy conversion of another mode, but the efficiency depends on the frequency ratio of the two modes. The vibration of one mode affects the energy conversion of another mode only when the frequency ratio of the two modes takes some special values. Discussions are also given on the potential application of the theoretical results in the design of an energy harvesting device. (paper)
International Nuclear Information System (INIS)
Sanmamed, Yolanda A.; Dopazo-Paz, Ana; Gonzalez-Salgado, Diego; Troncoso, Jacobo; Romani, Luis
2009-01-01
A calibration procedure of vibrating tube densimeters for density measurement of liquids in the intervals (700 to 1600) kg . m -3 , (283.15 to 323.15) K, and (0.1 to 60) MPa is presented. It is based on the modelization of the vibrating tube as a thick-tube clamped at one end (cantilever) whose stress and thermal behaviour follows the ideas proposed in the Forced Path Mechanical Calibration model (FPMC). Model parameters are determined using two calibration fluids with densities certified at atmospheric pressure (dodecane and tetracholoroethylene) and a third one with densities known as a function of pressure (water). It is applied to the Anton Paar 512P densimeter, obtaining density measurements with an expanded uncertainty less than 0.2 kg . m -3 in the working intervals. This accuracy comes from the combination of several factors: densimeter behaves linearly in the working density interval, densities of both calibration fluids cover that interval and they have a very low uncertainty, and the mechanical behaviour of the tube is well characterized by the considered model. The main application of this method is the precise measurement of high density fluids for which most of the calibration procedures are inaccurate.
Vibration Analysis of Rectangular Plates with One or More Guided Edges via Bicubic B-Spline Method
Directory of Open Access Journals (Sweden)
W.J. Si
2005-01-01
Full Text Available A simple and accurate method is proposed for the vibration analysis of rectangular plates with one or more guided edges, in which bicubic B-spline interpolation in combination with a new type of basis cubic B-spline functions is used to approximate the plate deflection. This type of basis cubic B-spline functions can satisfy simply supported, clamped, free, and guided edge conditions with easy numerical manipulation. The frequency characteristic equation is formulated based on classical thin plate theory by performing Hamilton's principle. The present solutions are verified with the analytical ones. Fast convergence, high accuracy and computational efficiency have been demonstrated from the comparisons. Frequency parameters for 13 cases of rectangular plates with at least one guided edge, which are possible by approximate or numerical methods only, are presented. These results are new in literature.
Arjunan, V; Rani, T; Santhanam, R; Mohan, S
2012-10-01
The FT-IR and FT-Raman spectra of H bond inner conformer of 2,3-epoxypropanol have been recorded in the regions 3700-400 and 3700-100 cm(-1), respectively. The spectra were interpreted in terms of fundamentals modes, combination and overtone bands. The normal coordinate analysis was carried out to confirm the precision of the assignments. The structure of the conformers H bond inner and H bond outer1 were optimised and the structural characteristics were determined by density functional theory (DFT) using B3LYP and MP2 methods with 6-31G** and 6-311++G** basis sets. The vibrational frequencies were calculated in all these methods and were compared with the experimental frequencies which yield good agreement between observed and calculated frequencies. The electronic properties HOMO and LUMO energies were measured by time-dependent TD-DFT approach. Copyright © 2012 Elsevier B.V. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Permoon, M. R.; Haddadpour, H. [Sharif University of Tech, Tehran (Iran, Islamic Republic of); Rashidinia, J.; Parsa, A.; Salehi, R. [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)
2016-07-15
In this paper, the forced vibrations of the fractional viscoelastic beam with the Kelvin-Voigt fractional order constitutive relationship is studied. The equation of motion is derived from Newton's second law and the Galerkin method is used to discretize the equation of motion in to a set of linear ordinary differential equations. For solving the discretized equations, the radial basis functions and Sinc quadrature rule are used. In order to show the effectiveness and accuracy of this method, some test problem are considered, and it is shown that the obtained results are in very good agreement with exact solution. In the following, the proposed numerical solution is applied to exploring the effects of fractional parameters on the response of the beam and finally some conclusions are outlined.
Analyzing Damping Vibration Methods of Large-Size Space Vehicles in the Earth's Magnetic Field
Directory of Open Access Journals (Sweden)
G. A. Shcheglov
2016-01-01
Full Text Available It is known that most of today's space vehicles comprise large antennas, which are bracket-attached to the vehicle body. Dimensions of reflector antennas may be of 30 ... 50 m. The weight of such constructions can reach approximately 200 kg.Since the antenna dimensions are significantly larger than the size of the vehicle body and the points to attach the brackets to the space vehicles have a low stiffness, conventional dampers may be inefficient. The paper proposes to consider the damping antenna in terms of its interaction with the Earth's magnetic field.A simple dynamic model of the space vehicle equipped with a large-size structure is built. The space vehicle is a parallelepiped to which the antenna is attached through a beam.To solve the model problems, was used a simplified model of Earth's magnetic field: uniform, with intensity lines parallel to each other and perpendicular to the plane of the antenna.The paper considers two layouts of coils with respect to the antenna, namely: a vertical one in which an axis of magnetic dipole is perpendicular to the antenna plane, and a horizontal layout in which an axis of magnetic dipole lies in the antenna plane. It also explores two ways for magnetic damping of oscillations: through the controlled current that is supplied from the power supply system of the space vehicle, and by the self-induction current in the coil. Thus, four objectives were formulated.In each task was formulated an oscillation equation. Then a ratio of oscillation amplitudes and their decay time were estimated. It was found that each task requires the certain parameters either of the antenna itself, its dimensions and moment of inertia, or of the coil and, respectively, the current, which is supplied from the space vehicle. In each task for these parameters were found the ranges, which allow us to tell of efficient damping vibrations.The conclusion can be drawn based on the analysis of tasks that a specialized control system
Reproducibility of ultrasonic testing
International Nuclear Information System (INIS)
Lecomte, J.-C.; Thomas, Andre; Launay, J.-P.; Martin, Pierre
The reproducibility of amplitude quotations for both artificial and natural reflectors was studied for several combinations of instrument/search unit, all being of the same type. This study shows that in industrial inspection if a range of standardized equipment is used, a margin of error of about 6 decibels has to be taken into account (confidence interval of 95%). This margin is about 4 to 5 dB for natural or artificial defects located in the central area and about 6 to 7 dB for artificial defects located on the back surface. This lack of reproducibility seems to be attributable first to the search unit and then to the instrument and operator. These results were confirmed by analysis of calibration data obtained from 250 tests performed by 25 operators under shop conditions. The margin of error was higher than the 6 dB obtained in the study [fr
Investigation of silicate mineral sanidine by vibrational and NMR spectroscopic methods
Anbalagan, G.; Sankari, G.; Ponnusamy, S.; kumar, R. Thilak; Gunasekaran, S.
2009-10-01
Sanidine, a variety of feldspar minerals has been investigated through optical absorption, vibrational (IR and Raman), EPR and NMR spectroscopic techniques. The principal reflections occurring at the d-spacings, 3.2892, 3.2431, 2.9022 and 2.6041 Å confirm the presence of sanidine structure in the mineral. Sanidine shows five prominent characteristic infrared absorption bands in the region 1200-950, 770-720, 590-540 and 650-640 cm -1. The Raman spectrum shows the strongest band at 512 cm -1 characteristic of the feldspar structure, which contains four membered rings of tetrahedra. The UV-vis-NIR absorption spectrum had strong absorption features at 6757, 5780 and 5181 cm -1 due to the combination of fundamental OH- stretching. The bands at 11236 and 8196 cm -1and the strong, well-defined band at (30303 cm -1 attest the presence of Fe 2+ and Fe 3+, respectively, in the sample. The signals at g = 4.3 and 3.7 are interpreted in terms of Fe 3+ at two distinct tetrahedral positions Tl and T2 of the monoclinic crystal structure The 29Si NMR spectrum shows two peaks at -97 and -101 ppm corresponding to T2 and T1, respectively, and one peak in 27Al NMR for Al(IV).
International Nuclear Information System (INIS)
Schmidt, Victor
2014-01-01
The techniques H/V, FK and SPAC were applied, all based on the measurement of surface waves main generated by ambient vibrations, for the soil characterization of 15 selected sites. 12 of them corresponding to accelerographic stations of the Laboratorio de Ingenieria Sismica of the Universidad de Costa Rica. 8 sensors (triaxial geophones) were placed for that purpose in circular arrayz, and spectral ratios (from H/V) dispersion curves (from FK) and autocorrelation curves (from SPAC) were obtained for each site considered. The soil type was determined, based on above, according to the site characteristic period (T 0 ) read from H/V. Each site was also classified according to the Seismic Code of Costa Rica (2010) and the parameter Vs30 calculated from the inversion of dispersion curves and autocorrelation. The values of T 0 vary between 0,3 s to 1,5 s and the Vs30 between 244 m/s to 379 m/s have indicated that soils correspond to S 3 (soft soil, 67% of all cases). The discovery of sites whose classification corresponds to S 1 (rock) or S 4 (very soft soil) was discarded. (author) [es
Energy Technology Data Exchange (ETDEWEB)
Alekhin, S.A.; Chernov, V.S.; Denisenko, V.V.; Gorodnyanskiy, I.F.; Prokopov, L.I.; Tikhonov, Yu.P.
1983-01-01
The vibration mixer is proposed which contains a housing, vibration drive with rod installed in the upper part of the mixing mechanism made in the form of a hollow shaft with blades. In order to improve intensity of mixing and dispersion of the mud, the shaft with the blades is arranged on the rod of the vibrator and is equipped with a cam coupling whose drive disc is attached to the vibration rod. The rod is made helical, while the drive disc of the cam coupling is attached to the helical surface of the rod. In addition, the vibration mixer is equipped with perforated discs installed on the ends of the rods.
International Nuclear Information System (INIS)
Wang Xin; Zhong Renming; Bai Sen; Xu Qingfeng; Zhao Yaqin; Wang Jin; Jiang Xiaoqin; Shen Yali; Xu Feng; Wei Yuquan
2011-01-01
Purpose: To study the inter- and intrafraction tumor reproducibility with active breath control (ABC) utilizing cone-beam computed tomography (CBCT), and compare validity of registration with two different regions of interest (ROI). Methods and materials: Thirty-one lung tumors in 19 patients received conventional or stereotactic body radiotherapy with ABC. During each treatment, patients had three CBCT scanned before and after online position correction and after treatment. These CBCT images were aligned to the planning CT using the gray scale registration of tumor and bony registration of the thorax, and tumor position uncertainties were then determined. Results: The interfraction systematic and random translation errors in the left-right (LR), superior-inferior (SI) and anterior-posterior (AP) directions were 3.6, 4.8, and 2.9 mm; 2.5, 4.5, and 3.5 mm, respectively, with gray scale alignment; 1.9, 4.3, 2.0 mm and 2.5, 4.4, 2.9 mm, respectively, with bony alignment. The interfraction systematic and random rotation errors with gray scale and bony alignment groups ranged from 1.4 o to 3.0 o and 0.8 o to 2.3 o , respectively. The intrafraction systematic and random errors with gray scale registration in LR, SI, AP directions were 0.9, 2.0, 1.8 mm and 1.5, 1.7, 2.9 mm, respectively, for translation; 1.5 o , 0.9 o , 1.0 o and 1.2 o , 2.2 o , 1.8 o , respectively, for rotation. The translational errors in SI direction with bony alignment were significantly larger than that of gray scale (p < 0.05). Conclusions: With CBCT guided online correction the interfraction positioning errors can be markedly reduced. The intrafraction errors were not diminished by the use of ABC. Rotation errors were not very remarkable both inter- and intrafraction. Gray scale alignment of tumor may provide a better registration in SI direction.
Directory of Open Access Journals (Sweden)
G. H. Rahimi
2014-01-01
Full Text Available A three-dimensional elasticity theory by means of a state-space based differential quadrature method is presented for free vibration analysis of fiber metal laminate annular plate. The kinds of composite material and metal layers are considered to be S2-glass and aluminum, respectively. A semianalytical approach which uses state-space in the thickness and differential quadrature in the radial direction is implemented for evaluating the nondimensional natural frequencies of the annular plates. The influences of changes in boundary condition, plate thickness, and lay-up direction on the natural frequencies are studied. A comparison is also made with the numerical results reported by ABAQUS software which shows an excellent agreement.
International Nuclear Information System (INIS)
Tang, H.T.; Nakamura, N.
1995-01-01
A 1/4-scale cylindrical reactor containment model was constructed in Hualien, Taiwan for foil-structure interaction (SSI) effect evaluation and SSI analysis procedure verification. Forced vibration tests were executed before backfill (FVT-1) and after backfill (FVT-2) to characterize soil-structure system characteristics under low excitations. A number of organizations participated in the pre-test blind prediction and post-test correlation analyses of the forced vibration test using various industry familiar methods. In the current study, correlation analyses were performed using a three-dimensional flexible volume substructuring method. The results are reported and soil property sensitivities are evaluated in the paper. (J.P.N.)
Scott, Andrew D; Keegan, Jennifer; Firmin, David N
2011-01-01
To quantitatively assess the performance and reproducibility of 3D spiral coronary artery wall imaging with beat-to-beat respiratory-motion-correction (B2B-RMC) compared to navigator gated 2D spiral and turbo-spin-echo (TSE) acquisitions. High-resolution (0.7 × 0.7 mm) cross-sectional right coronary wall acquisitions were performed in 10 subjects using four techniques (B2B-RMC 3D spiral with alternate (2RR) and single (1RR) R-wave gating, navigator-gated 2D spiral (2RR) and navigator-gated 2D TSE (2RR)) on two occasions. Wall thickness measurements were compared with repeated measures analysis of variance (ANOVA). Reproducibility was assessed with the intraclass correlation coefficient (ICC). In all, 91% (73/80) of acquisitions were successful (failures: four TSE, two 3D spiral (1RR) and one 3D spiral (2RR)). Respiratory efficiency of the B2B-RMC was less variable and substantially higher than for navigator gating (99.6 ± 1.2% vs. 39.0 ± 7.5%, P B2B-RMC permits coronary vessel wall assessment over multiple thin contiguous slices in a clinically feasible duration. Excellent reproducibility of the technique potentially enables studies of disease progression/regression. Copyright © 2010 Wiley-Liss, Inc.
Hansson, J E; Eklund, L; Kihlberg, S; Ostergren, C E
1987-03-01
The main objective of the study was to find efficient hand tools which caused only minor vibration loading. Vibration measurements were carried out under standardised working conditions. The time during which car body repairers in seven companies were exposed to vibration was determined. Chisel hammers, impact wrenches, sanders and saws were the types of tools which generated the highest vibration accelerations. The average daily exposure at the different garages ranged from 22 to 70 min. The risk of vibration injury is currently rated as high. The difference between the highest and lowest levels of vibration was considerable in most tool categories. Therefore the choice of tool has a major impact on the magnitude of vibration exposure. The importance of choosing the right tools and working methods is discussed and a counselling service on vibration is proposed.
Magnet stability and reproducibility
Marks, N
2010-01-01
Magnet stability and reproducibility have become increasingly important as greater precision and beams with smaller dimension are required for research, medical and other purpose. The observed causes of mechanical and electrical instability are introduced and the engineering arrangements needed to minimize these problems discussed; the resulting performance of a state-of-the-art synchrotron source (Diamond) is then presented. The need for orbit feedback to obtain best possible beam stability is briefly introduced, but omitting any details of the necessary technical equipment, which is outside the scope of the presentation.
Reproducible research in palaeomagnetism
Lurcock, Pontus; Florindo, Fabio
2015-04-01
The reproducibility of research findings is attracting increasing attention across all scientific disciplines. In palaeomagnetism as elsewhere, computer-based analysis techniques are becoming more commonplace, complex, and diverse. Analyses can often be difficult to reproduce from scratch, both for the original researchers and for others seeking to build on the work. We present a palaeomagnetic plotting and analysis program designed to make reproducibility easier. Part of the problem is the divide between interactive and scripted (batch) analysis programs. An interactive desktop program with a graphical interface is a powerful tool for exploring data and iteratively refining analyses, but usually cannot operate without human interaction. This makes it impossible to re-run an analysis automatically, or to integrate it into a larger automated scientific workflow - for example, a script to generate figures and tables for a paper. In some cases the parameters of the analysis process itself are not saved explicitly, making it hard to repeat or improve the analysis even with human interaction. Conversely, non-interactive batch tools can be controlled by pre-written scripts and configuration files, allowing an analysis to be 'replayed' automatically from the raw data. However, this advantage comes at the expense of exploratory capability: iteratively improving an analysis entails a time-consuming cycle of editing scripts, running them, and viewing the output. Batch tools also tend to require more computer expertise from their users. PuffinPlot is a palaeomagnetic plotting and analysis program which aims to bridge this gap. First released in 2012, it offers both an interactive, user-friendly desktop interface and a batch scripting interface, both making use of the same core library of palaeomagnetic functions. We present new improvements to the program that help to integrate the interactive and batch approaches, allowing an analysis to be interactively explored and refined
de Goeje, Marius; van Overbeek, Michiel Wilbert R.M.; van der Waal, Adri; Berkhoff, Arthur P.; Nederveen, Peter J.
2005-01-01
A semimanufacture intended to be mounted on a vibrating wall or a vibrating panel for actively damping the vibrations in the wall or the panel with frequencies which are at least partly audible, wherein the semimanufacture is provided with a plate wherein the plate is integrated with: at least one
Investigation of Tension Forces in A Stay Cable System of A Road Bridge Using Vibration Methods
Directory of Open Access Journals (Sweden)
Hawryszków Paweł
2015-01-01
Full Text Available In the article author presents method of investigation of tension forces in stay cable systems using dynamical methods. Research was carried out during stay cable system installation on WN-24 viaduct near Poznań, that is way it was possible to compare tension forces indicated directly by devices using for tensioning of cable-stayed bridges with results achieved indirectly by means of dynamical methods. Discussion of results was presented. Advantages of dynamical methods and possible fields of application was described. This method, which has been rarely used before, may occur interesting alternative in diagnostics of bridges in comparison to traditional methods.
Fedorov, Oleg
2016-07-01
Space materials science is one of the priorities of different national and international space programs. The physical processes of heat and mass transfer in microgravity (including effect of g-jitter) is far from complete clarity, especially for important practical technology for producing crystals from the melt. The idea of the impact on crystallizing melt by low frequency vibration includes not only the possibility to suppress unwanted microaccelerations, but also to actively influence the structure of the crystallization front. This approach is one of the most effective ways to influence the quality of materials produced in flight conditions. The subject of this work is the effect of vibrations on the thermal and hydrodynamic processes during crystal growth using Bridgman and floating zone techniques, which have the greatest prospect of practical application in space. In the present approach we consider the gravitational convection, Marangoni convection, as well as the effect of vibration on the melt for some special cases. The results of simulation were compared with some experimental data obtained by the authors using a transparent model substance - succinonitrile (Bridgman method), and silicon (floating zone method). Substances used, process parameters and characteristics of the experimental units correspond the equipment developed for onboard research and serve as a basis for selecting optimum conditions vibration exposure as a factor affecting the solidification pattern. The direction of imposing vibrations coincides with the axis of the crystal, the frequency is presented by the harmonic law, and the force of gravity was varied by changing its absolute value. Mathematical model considered axisymmetric approximation of joint convective-conductive energy transfer in the system crystal - melt. Upon application of low-frequency oscillations of small amplitude along the axis of growing it was found the suppression of the secondary vortex flows near the
Energy-dependent collisional deactivation of vibrationally excited azulene
International Nuclear Information System (INIS)
Shi, J.; Barker, J.R.
1988-01-01
Collisional energy transfer parameters for highly vibrationally excited azulene have been deduced from new infrared fluorescence (IRF) emission lifetime data with an improved calibration relating IRF intensity to vibrational energy [J. Shi, D. Bernfeld, and J. R. Barker, J. Chem. Phys. 88, XXXX (1988), preceding paper]. In addition, data from previous experiments [M. J. Rossi, J. R. Pladziewicz, and J. R. Barker, J. Chem. Phys. 78, 6695 (1983)] have been reanalyzed based on the improved calibration. Inversion of the IRF decay curves produced plots of energy decay, which were analyzed to determine , the average energy transferred per collision. Master equation simulations reproduced both the original IRF decays and the deduced energy decays. A third (simple) method of determination agrees well with the other two. The results show to be nearly directly proportional to the vibrational energy of the excited azulene from ∼8000 to 33 000 cm -1 . At high energies, there are indications that the energy dependence may be slightly reduced
Koroleva, L. A.; Tyulin, V. I.; Matveev, V. K.; Pentin, Yu. A.
2013-05-01
B3LYP, MP2, CCSD(T), and MP4/MP2 in the 6-311G( d, p), 6-311++G( d, p), cc-pVTZ, aug-cc-pVTZ bases used to calculate the transition frequencies of torsional vibration of trans- and cis-isomers of acrolein in the ground electronic state ( S 0) are analyzed. It is found that for trans-isomers, all methods of calculation except for B3LYP in the cc-pVTZ basis yield good agreement between the calculated and experimental values. It is noted that for the cis-isomer of acrolein, no method of calculation confirms the experimental value of the frequency of torsional vibration (138 cm-1). It is shown that the calculated and experimental values for obertones at 273.0 cm-1 and other transitions of torsional vibration are different for this isomer in particular. However, it is established that in some calculation methods (B3LYP, MP2), the frequency of the torsional vibration of the cis-isomer coincides with another experimental value of this frequency (166.5 cm-1). It is concluded that in analyzing the vibrational structure of the UV spectrum, the calculated and experimental values of its obertone (331.3 cm-1) coincide, along with its frequency. It is also noted that the frequency of torsional vibration for the cis-isomer (166.5 cm-1) can also be found in other experimental works if we change the allocation of torsional transition 18{1/1}.
Reproducibility principles, problems, practices, and prospects
Maasen, Sabine
2016-01-01
Featuring peer-reviewed contributions from noted experts in their fields of research, Reproducibility: Principles, Problems, Practices, and Prospects presents state-of-the-art approaches to reproducibility, the gold standard sound science, from multi- and interdisciplinary perspectives. Including comprehensive coverage for implementing and reflecting the norm of reproducibility in various pertinent fields of research, the book focuses on how the reproducibility of results is applied, how it may be limited, and how such limitations can be understood or even controlled in the natural sciences, computational sciences, life sciences, social sciences, and studies of science and technology. The book presents many chapters devoted to a variety of methods and techniques, as well as their epistemic and ontological underpinnings, which have been developed to safeguard reproducible research and curtail deficits and failures. The book also investigates the political, historical, and social practices that underlie repro...
Localization of Vibrating Noise Sources in Nuclear Reactor Cores
International Nuclear Information System (INIS)
Hultqvist, Pontus
2004-09-01
In this thesis the possibility of locating vibrating noise sources in a nuclear reactor core from the neutron noise has been investigated using different localization methods. The influence of the vibrating noise source has been considered to be a small perturbation of the neutron flux inside the reactor. Linear perturbation theory has been used to construct the theoretical framework upon which the localization methods are based. Two different cases have been considered: one where a one-dimensional one-group model has been used and another where a two-dimensional two-energy group noise simulator has been used. In the first case only one localization method is able to determine the position with good accuracy. This localization method is based on finding roots of an equation and is sensitive to other perturbations of the neutron flux. It will therefore work better with the assistance of approximative methods that reconstruct the noise source to determine if the results are reliable or not. In the two-dimensional case the results are more promising. There are several different localization techniques that reproduce both the vibrating noise source position and the direction of vibration with enough precision. The approximate methods that reconstruct the noise source are substantially better and are able to support the root finding method in a more constructive way. By combining the methods, the results will be more reliable
Liu, Tao; Lyu, Mindong; Wang, Zixi; Yan, Shaoze
2018-02-01
Identification of orbit responses can make the active protection operation more easily realize for active magnetic bearings (AMB) in case of touchdowns. This paper presents an identification method of the orbit responses rooting on signal processing of rotor displacements during touchdowns. The recognition method consists of two major steps. Firstly, the combined rub and bouncing is distinguished from the other orbit responses by the mathematical expectation of axis displacements of the rotor. Because when the combined rub and bouncing occurs, the rotor of AMB will not be always close to the touchdown bearings (TDB). Secondly, we recognize the pendulum vibration and the full rub by the Fourier spectrum of displacement in horizontal direction, as the frequency characteristics of the two responses are different. The principle of the whole identification algorithm is illustrated by two sets of signal generated by a dynamic model of the specific rotor-TDB system. The universality of the method is validated by other four sets of signal. Besides, the adaptability of noise is also tested by adding white noises with different strengths, and the result is promising. As the mathematical expectation and Discrete Fourier transform are major calculations of the algorithm, the calculation quantity of the algorithm is low, so it is fast, easily realized and embedded in the AMB controller, which has an important engineering value for the protection of AMBs during touchdowns.
Energy Technology Data Exchange (ETDEWEB)
Friese, Daniel H., E-mail: daniel.h.friese@uit.no [Centre for Theoretical and Computational Chemistry CTCC, Department of Chemistry, University of Tromsø, N-9037 Tromsø (Norway); Törk, Lisa; Hättig, Christof, E-mail: christof.haettig@rub.de [Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44801 Bochum (Germany)
2014-11-21
We present scaling factors for vibrational frequencies calculated within the harmonic approximation and the correlated wave-function methods coupled cluster singles and doubles model (CC2) and Møller-Plesset perturbation theory (MP2) with and without a spin-component scaling (SCS or spin-opposite scaling (SOS)). Frequency scaling factors and the remaining deviations from the reference data are evaluated for several non-augmented basis sets of the cc-pVXZ family of generally contracted correlation-consistent basis sets as well as for the segmented contracted TZVPP basis. We find that the SCS and SOS variants of CC2 and MP2 lead to a slightly better accuracy for the scaled vibrational frequencies. The determined frequency scaling factors can also be used for vibrational frequencies calculated for excited states through response theory with CC2 and the algebraic diagrammatic construction through second order and their spin-component scaled variants.
Directory of Open Access Journals (Sweden)
SW Kang
2015-02-01
Full Text Available This article introduces an improved non-dimensional dynamic influence function method using a sub-domain method for efficiently extracting the eigenvalues and mode shapes of concave membranes with arbitrary shapes. The non-dimensional dynamic influence function method (non-dimensional dynamic influence function method, which was developed by the authors in 1999, gives highly accurate eigenvalues for membranes, plates, and acoustic cavities, compared with the finite element method. However, it needs the inefficient procedure of calculating the singularity of a system matrix in the frequency range of interest for extracting eigenvalues and mode shapes. To overcome the inefficient procedure, this article proposes a practical approach to make the system matrix equation of the concave membrane of interest into a form of algebraic eigenvalue problem. It is shown by several case studies that the proposed method has a good convergence characteristics and yields very accurate eigenvalues, compared with an exact method and finite element method (ANSYS.
CSIR Research Space (South Africa)
Veldman, CS
2003-01-01
Full Text Available -11. The signal processing required for the successful implementation of this method of ISO 16063-11 has been implemented by various metrology institutes using various techniques. For the implementation of these techniques, different hardware and software...
Dynamic Error Analysis Method for Vibration Shape Reconstruction of Smart FBG Plate Structure
Directory of Open Access Journals (Sweden)
Hesheng Zhang
2016-01-01
Full Text Available Shape reconstruction of aerospace plate structure is an important issue for safe operation of aerospace vehicles. One way to achieve such reconstruction is by constructing smart fiber Bragg grating (FBG plate structure with discrete distributed FBG sensor arrays using reconstruction algorithms in which error analysis of reconstruction algorithm is a key link. Considering that traditional error analysis methods can only deal with static data, a new dynamic data error analysis method are proposed based on LMS algorithm for shape reconstruction of smart FBG plate structure. Firstly, smart FBG structure and orthogonal curved network based reconstruction method is introduced. Then, a dynamic error analysis model is proposed for dynamic reconstruction error analysis. Thirdly, the parameter identification is done for the proposed dynamic error analysis model based on least mean square (LMS algorithm. Finally, an experimental verification platform is constructed and experimental dynamic reconstruction analysis is done. Experimental results show that the dynamic characteristics of the reconstruction performance for plate structure can be obtained accurately based on the proposed dynamic error analysis method. The proposed method can also be used for other data acquisition systems and data processing systems as a general error analysis method.
Energy Technology Data Exchange (ETDEWEB)
Marienfeld, P.M.; Karkosch, H.J. [ContiTech Vibration Control GmbH, Hannover (Germany); Bohn, C. [Technische Univ. Clausthal (Germany); Svaricek, F. [Univ. der Bundeswehr Muenchen (Germany); Knake-Langhorst, S. [Deutsches Zentrum fuer Luft- und Raumfahrt, Braunschweig (Germany)
2008-07-01
In the automotive industry passive vibration absorbers are a well established method to reduce structural vibrations in automotive vehicles. Designing a vibration absorber consists of selecting its mechanical properties. Usually extensive tests are necessary with different absorbers in the vehicle and subjective as well as objective evaluation of the results. This requires hardware modifications between different tests. In this paper, an approach is proposed that can assist in the development of vibration absorbers. It is based on tuning an active vibration control system such that it reproduces the behavior of a specified vibration absorber. This behavior can then be changed electronically without modifying the hardware. Two different control approaches are compared. In the first approach, the apparent physical properties of a vibration absorber are directly modified through acceleration, velocity or displacement feedback. In the second approach, a desired dynamic mass transfer function for the vibration absorber is prescribed and an H2-norm optimal model matching problem is solved. Experimental results obtained with this approach are presented. (orig.)
A spectral dynamic stiffness method for free vibration analysis of plane elastodynamic problems
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.
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.
Application of Story-wise Shear Building Identification Method to Actual Ambient Vibration
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Kohei eFujita
2015-02-01
Full Text Available A sophisticated and smart story stiffness System Identification (SI method for a shear building model is applied to a full-scale building frame subjected to micro-tremors. The advantageous and novel feature is that not only the modal parameters, such as natural frequencies and damping ratios, but also the physical model parameters, such as story stiffnesses and damping coefficients, can be identified using micro-tremors. While the building responses to earthquake ground motions are necessary in the previous SI method, it is shown in this paper that the micro-tremor measurements in a full-scale 5 story building frame can be used for identification within the same framework. The SI using micro-tremor measurements leads to the enhanced usability of the previously proposed story-wise shear building identification method. The degree of ARX models and cut-off frequencies of band-pass filter are determined to derive reliable results.
Rossi, Mariana; Liu, Hanchao; Paesani, Francesco; Bowman, Joel; Ceriotti, Michele
2014-11-14
Including quantum mechanical effects on the dynamics of nuclei in the condensed phase is challenging, because the complexity of exact methods grows exponentially with the number of quantum degrees of freedom. Efforts to circumvent these limitations can be traced down to two approaches: methods that treat a small subset of the degrees of freedom with rigorous quantum mechanics, considering the rest of the system as a static or classical environment, and methods that treat the whole system quantum mechanically, but using approximate dynamics. Here, we perform a systematic comparison between these two philosophies for the description of quantum effects in vibrational spectroscopy, taking the Embedded Local Monomer model and a mixed quantum-classical model as representatives of the first family of methods, and centroid molecular dynamics and thermostatted ring polymer molecular dynamics as examples of the latter. We use as benchmarks D2O doped with HOD and pure H2O at three distinct thermodynamic state points (ice Ih at 150 K, and the liquid at 300 K and 600 K), modeled with the simple q-TIP4P/F potential energy and dipole moment surfaces. With few exceptions the different techniques yield IR absorption frequencies that are consistent with one another within a few tens of cm(-1). Comparison with classical molecular dynamics demonstrates the importance of nuclear quantum effects up to the highest temperature, and a detailed discussion of the discrepancies between the various methods let us draw some (circumstantial) conclusions about the impact of the very different approximations that underlie them. Such cross validation between radically different approaches could indicate a way forward to further improve the state of the art in simulations of condensed-phase quantum dynamics.
Slepian modeling as a computational method in random vibration analysis of hysteretic structures
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Tarp-Johansen, Niels Jacob
1999-01-01
white noise. The computation time for obtaining estimates of relevant statistics on a given accuracy level is decreased by factors of one ormore orders of size as compared to the computation time needed for direct elasto-plastic displacementresponse simulations by vectorial Markov sequence techniques....... Moreover the Slepian method gives valuablephysical insight about the details of the plastic displacement development by time.The paper gives a general self-contained mathematical description of the Slepian method based plasticdisplacement analysis of Gaussian white noise excited EPOs. Experiences...
Vibrations And Deformations Of Moderately Thick Plates In Stochastic Finite Element Method
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Grzywiński Maksym
2015-12-01
Full Text Available The paper deals with some chosen aspects of stochastic dynamical analysis of moderately thick plates. The discretization of the governing equations is described by the finite element method. The main aim of the study is to provide the generalized stochastic perturbation technique based on classical Taylor expansion with a single random variable.
International Nuclear Information System (INIS)
Ge, Gen; Li, ZePeng
2016-01-01
A modified stochastic averaging method on single-degree-of-freedom (SDOF) oscillators under white noise excitations with strongly nonlinearity was proposed. Considering the existing approach dealing with strongly nonlinear SDOFs derived by Zhu and Huang [14, 15] is quite time consuming in calculating the drift coefficient and diffusion coefficients and the expressions of them are considerable long, the so-called He's energy balance method was applied to overcome the minor defect of the Zhu and Huang's method. The modified method can offer more concise approximate expressions of the drift and diffusion coefficients without weakening the accuracy of predicting the responses of the systems too much by giving an averaged frequency beforehand. Three examples, a cubic and quadratic nonlinearity coexisting oscillator, a quadratic nonlinear oscillator under external white noise excitations and an externally excited Duffing–Rayleigh oscillator, were given to illustrate the approach we proposed. The three examples were excited by the Gaussian white noise and the Gaussian colored noise separately. The stationary responses of probability density of amplitudes and energy, together with joint probability density of displacement and velocity are studied to verify the presented approach. The reliability of the systems were also investigated to offer further support. Digital simulations were carried out and the output of that are coincide with the theoretical approximations well.
Di Maio, D.; Ewins, D. J.
2012-04-01
The study of dynamic properties of rotating structures, such as bladed discs, can be conveniently done using simple bladed discs where the blades do not have staggering angles. Simplified design, although not truly representative of real structures, can be easy and economic to manufacture and, still, very helpful for studying specific dynamic properties. An example of this can be called as mass mistune blisk study. Experimental measurements of vibrations of bladed discs under rotating conditions can be performed using Scanning Laser Doppler Vibrometer (SLDV) systems. However, in the aerospace industry, the vibrations of complex bladed discs must be measured under operating conditions which are more hostile than laboratory simulations. The Blade Tip Timing (BTT) measurement method is a measurement technique, which can be used to measure vibrations of bladed discs of an engine aircraft under operating conditions. However, the BTT technique is ineffective when used with a flat bladed disc whose blade vibrations cannot be measured. This can be detrimental when the use of controlled dynamic parameters, such as those obtained from a simple bladed disc design, can improve the confidence for the validation of post-processing software. This paper presents a work about experimental measurements of a simple bladed disc design whose vibrations were measured synchronously by Scanning LDV and BTT measurement systems. A rotating test rig and its mechanical modifications for the installation of the BTT probes are introduced. Implications of rotating a specimen inconsistently are presented so as solutions to obtained constant revolving speed. The experimental comparisons of forced response vibrations measured synchronously at one blade are presented and explained.
International Nuclear Information System (INIS)
Pickett, T.J.; Shirts, R.B.
1991-01-01
Based on work by Martens and Ezra and partially developed independently by Eaker, we apply an improved method of approximating the quantum energy levels of a system of coupled oscillators using the fast-Fourier transform of classical coordinates and momenta to find quantizing trajectories. Application is made to a two-dimensional system modeling the stretching motions of the HDO molecule. The results are in excellent agreement with quantum calculations. This method is useful because: (1) it gives results which are independent of any separability of the Hamiltonian, (2) it is not limited in the number of degrees of freedom that can be handled, and (3) no zero-order approximation to the system is necessary. Results are equally valid inside and outside of resonance zones
A Practical Method to Increase the Frequency Readability for Vibration Signals
Directory of Open Access Journals (Sweden)
Jean Loius Ntakpe
2016-10-01
Full Text Available Damage detection and nondestructive evaluation of mechanical and civil engineering structures are nowadays very important to assess the integrity and ensure the reliability of structures. Thus, frequency evaluation becomes a crucial issue, since this modal parameter is mainly used in structural integrity assessment. The herein presented study highligts the possibility of increasing the frequency readability by involving a simple and cost-effective method.
Structural health monitoring of a railway truss bridge using vibration-based and ultrasonic methods
Kołakowski, Przemysław; Szelążek, Jacek; Sekuła, Krzysztof; Świercz, Andrzej; Mizerski, Krzysztof; Gutkiewicz, Piotr
2011-03-01
This paper presents results of in situ investigation of a railway truss bridge in the context of structural health monitoring (SHM). Three experimental methods are examined. Dynamic responses of the bridge recorded by strain gauges are confronted with alternative ways of acquisition using piezoelectric patch sensors and ultrasonic probeheads. All types of sensors produce similar output. Also the corresponding responses of the numerical model of the bridge match experimental data.
Structural health monitoring of a railway truss bridge using vibration-based and ultrasonic methods
International Nuclear Information System (INIS)
Kołakowski, Przemysław; Sekuła, Krzysztof; Szelążek, Jacek; Świercz, Andrzej; Mizerski, Krzysztof; Gutkiewicz, Piotr
2011-01-01
This paper presents results of in situ investigation of a railway truss bridge in the context of structural health monitoring (SHM). Three experimental methods are examined. Dynamic responses of the bridge recorded by strain gauges are confronted with alternative ways of acquisition using piezoelectric patch sensors and ultrasonic probeheads. All types of sensors produce similar output. Also the corresponding responses of the numerical model of the bridge match experimental data
International Nuclear Information System (INIS)
Trendafilova, I
2011-01-01
Vibration-based structural interrogation and health monitoring is a field which is concerned with the estimation of the current state of a structure or a component from its vibration response with regards to its ability to perform its intended function appropriately. One way to approach this problem is through damage features extracted from the measured structural vibration response. This paper suggests to use a new concept for the purposes of vibration-based health monitoring. The correlation between two signals, an input and an output, measured on the structure is used to develop a damage indicator. The paper investigates the applicability of the signal cross-correlation and a nonlinear alternative, the average mutual information between the two signals, for the purposes of structural health monitoring and damage assessment. The suggested methodology is applied and demonstrated for delamination detection in a composite beam.
Finite element random vibration method for soil-structure interaction analysis
International Nuclear Information System (INIS)
Romo-Organista, M.P.; Lysmer, J.; Seed, H.B.
1977-01-01
The authors present a method in which the seismic environment is defined directly in terms of the given design response spectrum. Response spectra cannot be used directly for random analysis, thus using extreme value theory a new procedure has been developed for converting the design response spectrum into a design power spectrum. This procedure is reversible and can also be used to compute response spectra the distribution of which can be expressed in terms of Confidence limits. Knowing the design power spctrum the resulting output power spectra and their statistical distribution can be computed by a response analysis of the soil-structure system in the frequency domain. Due to the complexity of soil structure systems, this is most conveniently done by the finite element method. Having obtained the power spectra for all motions in the system, these spectra can be used to determine other statistical information about the response such as maximum accelerations, stresses, bending moments, etc, all with appropriate confidence limits. This type of information is actually more useful for design than corresponding deterministic values. The authors have developed a computer program, PLUSH, which can perform the above procedures. Results obtained by the new method are in excellent agreement with the results of corresponding deterministic analysis. Furthermore, the probabilistic results can be obtained at a fraction of the cost of deterministic results
Directory of Open Access Journals (Sweden)
Tamer Ahmed El-Sayed
2017-01-01
Full Text Available The exact solution for multistepped Timoshenko beam is derived using a set of fundamental solutions. This set of solutions is derived to normalize the solution at the origin of the coordinates. The start, end, and intermediate boundary conditions involve concentrated masses and linear and rotational elastic supports. The beam start, end, and intermediate equations are assembled using the present normalized transfer matrix (NTM. The advantage of this method is that it is quicker than the standard method because the size of the complete system coefficient matrix is 4 × 4. In addition, during the assembly of this matrix, there are no inverse matrix steps required. The validity of this method is tested by comparing the results of the current method with the literature. Then the validity of the exact stepped analysis is checked using experimental and FE(3D methods. The experimental results for stepped beams with single step and two steps, for sixteen different test samples, are in excellent agreement with those of the three-dimensional finite element FE(3D. The comparison between the NTM method and the finite element method results shows that the modal percentage deviation is increased when a beam step location coincides with a peak point in the mode shape. Meanwhile, the deviation decreases when a beam step location coincides with a straight portion in the mode shape.
Application of eigenfunction orthogonalities to vibration problems
CSIR Research Space (South Africa)
Fedotov, I
2009-07-01
Full Text Available The modelling of vibration problems is of great importance in engineering. A popular method of analysing such problems is the variational method. The simplest vibration model is represented using the example of a long rod. Two kinds...
International Nuclear Information System (INIS)
Hao, W; Jinji, G
2012-01-01
Compressing the vibration signal of a rolling bearing has important significance to wireless monitoring and remote diagnosis of fans and pumps which is widely used in the petrochemical industry. In this paper, according to the characteristics of the vibration signal in a rolling bearing, a compression method based on the optimal selection of wavelet packet basis is proposed. We analyze several main attributes of wavelet packet basis and the effect to the compression of the vibration signal in a rolling bearing using wavelet packet transform in various compression ratios, and proposed a method to precisely select a wavelet packet basis. Through an actual signal, we come to the conclusion that an orthogonal wavelet packet basis with low vanishing moment should be used to compress the vibration signal of a rolling bearing to get an accurate energy proportion between the feature bands in the spectrum of reconstructing the signal. Within these low vanishing moments, orthogonal wavelet packet basis, and 'coif' wavelet packet basis can obtain the best signal-to-noise ratio in the same compression ratio for its best symmetry.
Real-Time Order Tracking of Gear Mesh Vibration in High Speed Planetary Gearboxes
Directory of Open Access Journals (Sweden)
Plöger Daniel Fritz
2018-01-01
Full Text Available Possible approaches to real-time order tracking are discussed. Two methods for real-time order tracking are developed and validated experimentally for the entire audible spectrum. An adaptive heterodyne filter bank is compared to a direct integral transform. The performance of both methods is adequate for usage in an active vibration control (AVC algorithm. Vold-Kalman filters are not suitable for AVC. The vibration data of three different planetary gearboxes is analyzed using order tracking. While some of the existing research could be reproduced, the data contradicts statements made by several authors. Lastly, the architecture of a novel AVC algorithm is sketched out.
Faster Simulation Methods for the Non-Stationary Random Vibrations of Non-Linear MDOF Systems
DEFF Research Database (Denmark)
Askar, A.; Köylüoglu, H. U.; Nielsen, Søren R. K.
subject to nonstationary Gaussian white noise excitation, as an alternative to conventional direct simulation methods. These alternative simulation procedures rely on an assumption of local Gaussianity during each time step. This assumption is tantamount to various linearizations of the equations....... Such a treatment offers higher rates of convergence, faster speed and higher accuracy. These procedures are compared to the direct Monte Carlo simulation procedure, which uses a fourth order Runge-Kutta scheme with the white noise process approximated by a broad band Ruiz-Penzien broken line process...
Faster Simulation Methods for the Nonstationary Random Vibrations of Non-linear MDOF Systems
DEFF Research Database (Denmark)
Askar, A.; Köylüo, U.; Nielsen, Søren R.K.
1996-01-01
subject to nonstationary Gaussian white noise excitation, as an alternative to conventional direct simulation methods. These alternative simulation procedures rely on an assumption of local Gaussianity during each time step. This assumption is tantamount to various linearizations of the equations....... Such a treatment offers higher rates of convergence, faster speed and higher accuracy. These procedures are compared to the direct Monte Carlo simulation procedure, which uses a fourth order Runge-Kutta scheme with the white noise process approximated by a broad band Ruiz-Penzien broken line process...
Garg, Hemanshul; Soti, Atul K.; Bhardwaj, Rajneesh
2018-02-01
We report the development of an in-house fluid-structure interaction solver and its application to vortex-induced vibration (VIV) of an elastically mounted cylinder in the presence of thermal buoyancy. The flow solver utilizes a sharp interface immersed boundary method, and in the present work, we extend it to account for the thermal buoyancy using Boussinesq approximation and couple it with a spring-mass system of the VIV. The one-way coupling utilizes an explicit time integration scheme and is computationally efficient. We present benchmark code verifications of the solver for natural convection, mixed convection, and VIV. In addition, we verify a coupled VIV-thermal buoyancy problem at a Reynolds number, Re = 150. We numerically demonstrate the onset of the VIV in the presence of the thermal buoyancy for an insulated cylinder at low Re. The buoyancy is induced by two parallel plates, kept in the direction of flow and symmetrically placed around the cylinder. The plates are maintained at the hot and cold temperature to the same degree relative to the ambient. In the absence of the thermal buoyancy (i.e., the plates are at ambient temperature), the VIV does not occur for Re ≤ 20 due to stable shear layers. By contrast, the thermal buoyancy induces flow instability and the vortex shedding helps us to achieve the VIV at Re ≤ 20, lower than the critical value of Re (≈21.7), reported in the literature, for a self-sustained VIV in the absence of the thermal buoyancy. The present simulations show that the lowest Re to achieve VIV in the presence of the thermal buoyancy is around Re ≈ 3, at Richardson number, Ri = 1. We examine the effect of the reduced velocity (UR), mass ratio (m), Prandtl number (Pr), Richardson number (Ri) on the displacement of the cylinder, lift coefficient, oscillation frequency, the phase difference between displacement and lift force, and wake structures. We obtain a significantly larger vibration amplitude of the cylinder over a wide
International Nuclear Information System (INIS)
Willner, K.
2006-01-01
A Mapped Fourier Grid method for solving the radial Schroedinger equation is improved. It is observed that a discrete sine and cosine transform algorithm allows to compute a Hamiltonian matrix the spectrum of which is free of spurious eigenvalues. - The energies of the highest, least bound vibrational states of the Na - Na 2 van der Waals complex are computed using a hyperspherical diabatic-by-sector method. The computed levels are analyzed using quantum defect theory. (orig.)
Directory of Open Access Journals (Sweden)
Elin Yusibani
2013-12-01
Full Text Available Application of a curved vibrating wire method (CVM to measure gas viscosity has been widely used. A ﬁne Tungsten wire with 50 mm of diameter is bent into a semi-circular shape and arranged symmetrically in a magnetic ﬁeld of about 0.2 T. The frequency domain is used for calculating the viscosity as a response for forced oscillation of the wire. Internal friction is one of the parameter in the CVM which is has to be measured beforeahead. Internal friction coefﬁcien for the wire material which is the inverse of the quality factor has to be measured in a vacuum condition. The term involving internal friction actually represents the effective resistance of motion due to all non-viscous damping phenomena including internal friction and magnetic damping. The testing of internal friction measurement shows that at different induced voltage and elevated temperature at a vacuum condition, it gives the value of internal friction for Tungsten is around 1 to 4 10-4.
International Nuclear Information System (INIS)
Bosselut, D.; Soulier, B.
1997-03-01
Some finite element models have been performed at EDF to simulate the vibrations of rod cluster and to analyse the wear phenomenon of rods using parametrical studies. In the first part, one of the finite element models is presented. The location of excitation sources is described. The calculated values are: rod displacement in the guiding cards, shock forces on the guiding cards and wear power produced. In the second part, a parametrical study is presented for a given computer experiment domain with an Experimental Design method. The building of the computer experiment design is described. The used polynomial model has all linear, quadratic and interactive terms for each of the 6 parameters (26 coefficients), 34 polynomials have been built to approach the effective shock forces and the mean wear power at each of the 17 guiding points. In the last part, the influence of parameters on calculated mean wear power is shown along rods and some responses surfaces are visualized. Systematism and closeness of experiment design technique is underlined. Easy simulation of all the response domain by polynomial approach, allows comparison with experiment feedback. (author)
Energy Technology Data Exchange (ETDEWEB)
Priola, Adriano Massimiliano; Priola, Sandro Massimo; Parlatano, Daniela; Gned, Dario; Veltri, Andrea [San Luigi Gonzaga University Hospital, Department of Diagnostic Imaging, Regione Gonzole 10, Orbassano, Torino (Italy); Giraudo, Maria Teresa [University of Torino, Department of Mathematics ' ' Giuseppe Peano' ' , Torino (Italy); Giardino, Roberto; Ardissone, Francesco [San Luigi Gonzaga University Hospital, Department of Thoracic Surgery, Regione Gonzole 10, Orbassano, Torino (Italy); Ferrero, Bruno [San Luigi Gonzaga University Hospital, Department of Neurology, Regione Gonzole 10, Orbassano, Torino (Italy)
2017-04-15
To investigate inter-reader reproducibility of five different region-of-interest (ROI) protocols for apparent diffusion coefficient (ADC) measurements in the anterior mediastinum. In eighty-one subjects, on ADC mapping, two readers measured the ADC using five methods of ROI positioning that encompassed the entire tissue (whole tissue volume [WTV], three slices observer-defined [TSOD], single-slice [SS]) or the more restricted areas (one small round ROI [OSR], multiple small round ROI [MSR]). Inter-observer variability was assessed with interclass correlation coefficient (ICC), coefficient of variation (CoV), and Bland-Altman analysis. Nonparametric tests were performed to compare the ADC between ROI methods. The measurement time was recorded and compared between ROI methods. All methods showed excellent inter-reader agreement with best and worst reproducibility in WTV and OSR, respectively (ICC, 0.937/0.874; CoV, 7.3 %/16.8 %; limits of agreement, ±0.44/±0.77 x 10{sup -3} mm{sup 2}/s). ADC values of OSR and MSR were significantly lower compared to the other methods in both readers (p < 0.001). The SS and OSR methods required less measurement time (14 ± 2 s) compared to the others (p < 0.0001), while the WTV method required the longest measurement time (90 ± 56 and 77 ± 49 s for each reader) (p < 0.0001). All methods demonstrate excellent inter-observer reproducibility with the best agreement in WTV, although it requires the longest measurement time. (orig.)
Jacobsen, Heiko
2011-12-23
The performance of a series of density functionals when tested on the prediction of the phosphane substitution energy of transition metal complexes is evaluated. The complexes Fe-BDA and Ru-COD (BDA=benzylideneacetone, COD=cyclooctadiene) serve as reference systems, and calculated values are compared with the experimental values in THF as obtained from calorimetry. Results clearly indicate that functionals specifically developed to include dispersion interactions usually outperform other functionals when BDA or COD substitution is considered. However, when phosphanes of different sizes are compared, functionals including dispersion interactions, at odd with experimental evidence, predict that larger phosphanes bind more strongly than smaller phosphanes, while functionals not including dispersion interaction reproduce the experimental trends with reasonable accuracy. In case of the DFT-D functionals, inclusion of a cut-off distance on the dispersive term resolves this issue, and results in a rather robust behavior whatever ligand substitution reaction is considered. Ne quid nimis: Describing chemical reactions in solution by computational techniques developed for gas-phase scenarios might produce erroneous results (see histogram). Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Yang, Yue; Gao, Hongwei
2012-04-01
Serotonin (5-hydroxytryptamine, 5-HT) is a monoamine neurotransmitter which plays an important role in treating acute or clinical stress. The comparative performance of different density functional theory (DFT) methods at various basis sets in predicting the molecular structure and vibration spectra of serotonin was reported. The calculation results of different methods including mPW1PW91, HCTH, SVWN, PBEPBE, B3PW91 and B3LYP with various basis sets including LANL2DZ, SDD, LANL2MB, 6-31G, 6-311++G and 6-311+G* were compared with the experimental data. It is remarkable that the SVWN/6-311++G and SVWN/6-311+G* levels afford the best quality to predict the structure of serotonin. The results also indicate that PBEPBE/LANL2DZ level show better performance in the vibration spectra prediction of serotonin than other DFT methods.
International Nuclear Information System (INIS)
Anjomshoa, Amin; Tahani, Masoud
2016-01-01
In the present study a continuum model based on the nonlocal elasticity theory is developed for free vibration analysis of embedded ortho tropic thick circular and elliptical nano-plates rested on an elastic foundation. The elastic foundation is considered to behave like a Pasternak type of foundations. Governing equations for vibrating nano-plate are derived according to the Mindlin plate theory in which the effects of shear deformations of nano-plate are also included. The Galerkin method is then employed to obtain the size dependent natural frequencies of nano-plate. The solution procedure considers the entire nano-plate as a single super-continuum element. Effect of nonlocal parameter, lengths of nano-plate, aspect ratio, mode number, material properties, thickness and foundation on circular frequencies are investigated. It is seen that the nonlocal frequencies of the nano-plate are smaller in comparison to those from the classical theory and this is more pronounced for small lengths and higher vibration modes. It is also found that as the aspect ratio increases or the nanoplate becomes more elliptical, the small scale effect on natural frequencies increases. Further, it is observed that the elastic foundation decreases the influence of nonlocal parameter on the results. Since the effect of shear deformations plays an important role in vibration analysis and design of nano-plates, by predicting smaller values for fundamental frequencies, the study of these nano-structures using thick plate theories such as Mindlin plate theory is essential.
Control model for dampening hand vibrations using information of internal and external coordinates.
Directory of Open Access Journals (Sweden)
Shunta Togo
Full Text Available In the present study, we investigate a control mechanism that dampens hand vibrations. Here, we propose a control method with two components to suppress hand vibrations. The first is a passive suppression method that lowers the joint stiffness to passively dampen the hand vibrations. The second is an active suppression method that adjusts an equilibrium point based on skyhook control to actively dampen the hand vibrations. In a simulation experiment, we applied these two methods to dampen hand vibrations during the shoulder's horizontal oscillation. We also conducted a measurement experiment wherein a subject's shoulder was sinusoidally oscillated by a platform that generated horizontal oscillations. The results of the measurement experiments showed that the jerk of each part of the arm in a task using a cup filled with water was smaller than the shoulder jerk and that in a task with a cup filled with stones was larger than the shoulder jerk. Moreover, the amplitude of the hand trajectory in both horizontal and vertical directions was smaller in a task using a cup filled with water than in a task using a cup filled with stones. The results of the measurement experiments were accurately reproduced by the active suppression method based on skyhook control. These results suggest that humans dampen hand vibrations by controlling the equilibrium point through the information of the external workspace and the internal body state rather than by lowering joint stiffness only by using internal information.
Reproducing Epidemiologic Research and Ensuring Transparency.
Coughlin, Steven S
2017-08-15
Measures for ensuring that epidemiologic studies are reproducible include making data sets and software available to other researchers so they can verify published findings, conduct alternative analyses of the data, and check for statistical errors or programming errors. Recent developments related to the reproducibility and transparency of epidemiologic studies include the creation of a global platform for sharing data from clinical trials and the anticipated future extension of the global platform to non-clinical trial data. Government agencies and departments such as the US Department of Veterans Affairs Cooperative Studies Program have also enhanced their data repositories and data sharing resources. The Institute of Medicine and the International Committee of Medical Journal Editors released guidance on sharing clinical trial data. The US National Institutes of Health has updated their data-sharing policies. In this issue of the Journal, Shepherd et al. (Am J Epidemiol. 2017;186:387-392) outline a pragmatic approach for reproducible research with sensitive data for studies for which data cannot be shared because of legal or ethical restrictions. Their proposed quasi-reproducible approach facilitates the dissemination of statistical methods and codes to independent researchers. Both reproducibility and quasi-reproducibility can increase transparency for critical evaluation, further dissemination of study methods, and expedite the exchange of ideas among researchers. © The Author(s) 2017. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.
Theoretical rotation-vibration spectrum of thioformaldehyde
International Nuclear Information System (INIS)
Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter
2013-01-01
We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H 2 CS. It covers 41 809 rovibrational levels for states up to J max = 30 with vibrational band origins up to 5000 cm −1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments
Theoretical rotation-vibration spectrum of thioformaldehyde
Yachmenev, Andrey; Polyak, Iakov; Thiel, Walter
2013-11-01
We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H2CS. It covers 41 809 rovibrational levels for states up to Jmax = 30 with vibrational band origins up to 5000 cm-1 and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments.
Theoretical rotation-vibration spectrum of thioformaldehyde
Energy Technology Data Exchange (ETDEWEB)
Yachmenev, Andrey [Department of Physics and Astronomy, University College London, London, WC1E 6BT (United Kingdom); Polyak, Iakov; Thiel, Walter [Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, D–45470 Mülheim an der Ruhr (Germany)
2013-11-28
We present a variational calculation of the first comprehensive T = 300 K rovibrational line list for thioformaldehyde, H{sub 2}CS. It covers 41 809 rovibrational levels for states up to J{sub max} = 30 with vibrational band origins up to 5000 cm{sup −1} and provides the energies and line intensities for 547 926 transitions from the ground vibrational state to these levels. It is based on our previously reported accurate ab initio potential energy surface and a newly calculated ab initio dipole moment surface. Minor empirical adjustments are made to the ab initio equilibrium geometry to reduce systematic errors in the predicted intra-band rotational energy levels. The rovibrational energy levels and transition intensities are computed variationally by using the methods implemented in the computer program TROVE. Transition wavelengths and intensities are found to be in excellent agreement with the available experimental data. The present calculations correctly reproduce the observed resonance effects, such as intensity borrowing, thus reflecting the high accuracy of the underlying ab initio surfaces. We report a detailed analysis of several vibrational bands, especially those complicated by strong Coriolis coupling, to facilitate future laboratory assignments.
DEFF Research Database (Denmark)
Morrison, Ann; Knudsen, L.; Andersen, Hans Jørgen
2012-01-01
In this paper we describe a field study conducted with a wearable vibration belt where we test to determine the vibration intensity sensitivity ranges on a large diverse group of participants with evenly distributed ages and...
International Nuclear Information System (INIS)
Torabi, K.; Nafar Dastgerdi, J.
2012-01-01
This paper is concerned with the free transverse vibration of cracked nanobeams modeled after Eringen's nonlocal elasticity theory and Timoshenko beam theory. The cracked beam is modeled as two segments connected by a rotational spring located at the cracked section. This model promotes discontinuities in rotational displacement due to bending which is proportional to bending moment transmitted by the cracked section. The governing equations of cracked nanobeams with two symmetric and asymmetric boundary conditions are derived; then these equations are solved analytically based on concerning basic standard trigonometric and hyperbolic functions. Besides, the frequency parameters and the vibration modes of cracked nanobeams for variant crack positions, crack ratio, and small scale effect parameters are calculated. The vibration solutions obtained provide a better representation of the vibration behavior of short, stubby, micro/nanobeams where the effects of small scale, transverse shear deformation and rotary inertia are significant. - Highlights: ► The free vibration analysis of cracked nanobeams is investigated. ► This study is based on the theory of nonlocal elasticity and Timoshenko beam theory. ► The small scale effect parameter greatly affects the value of natural frequencies. ► Crack reduces the natural frequencies, causes a discontinuity in the cracked section.
Energy Technology Data Exchange (ETDEWEB)
Torabi, K., E-mail: kvntrb@KashanU.ac.ir; Nafar Dastgerdi, J., E-mail: J.nafardastgerdi@me.iut.ac.ir
2012-08-31
This paper is concerned with the free transverse vibration of cracked nanobeams modeled after Eringen's nonlocal elasticity theory and Timoshenko beam theory. The cracked beam is modeled as two segments connected by a rotational spring located at the cracked section. This model promotes discontinuities in rotational displacement due to bending which is proportional to bending moment transmitted by the cracked section. The governing equations of cracked nanobeams with two symmetric and asymmetric boundary conditions are derived; then these equations are solved analytically based on concerning basic standard trigonometric and hyperbolic functions. Besides, the frequency parameters and the vibration modes of cracked nanobeams for variant crack positions, crack ratio, and small scale effect parameters are calculated. The vibration solutions obtained provide a better representation of the vibration behavior of short, stubby, micro/nanobeams where the effects of small scale, transverse shear deformation and rotary inertia are significant. - Highlights: Black-Right-Pointing-Pointer The free vibration analysis of cracked nanobeams is investigated. Black-Right-Pointing-Pointer This study is based on the theory of nonlocal elasticity and Timoshenko beam theory. Black-Right-Pointing-Pointer The small scale effect parameter greatly affects the value of natural frequencies. Black-Right-Pointing-Pointer Crack reduces the natural frequencies, causes a discontinuity in the cracked section.
Directory of Open Access Journals (Sweden)
Xingwu Zhang
2016-01-01
Full Text Available Milling vibration is one of the most serious factors affecting machining quality and precision. In this paper a novel hybrid error criterion-based frequency-domain LMS active control method is constructed and used for vibration suppression of milling processes by piezoelectric actuators and sensors, in which only one Fast Fourier Transform (FFT is used and no Inverse Fast Fourier Transform (IFFT is involved. The correction formulas are derived by a steepest descent procedure and the control parameters are analyzed and optimized. Then, a novel hybrid error criterion is constructed to improve the adaptability, reliability and anti-interference ability of the constructed control algorithm. Finally, based on piezoelectric actuators and acceleration sensors, a simulation of a spindle and a milling process experiment are presented to verify the proposed method. Besides, a protection program is added in the control flow to enhance the reliability of the control method in applications. The simulation and experiment results indicate that the proposed method is an effective and reliable way for on-line vibration suppression, and the machining quality can be obviously improved.
Reproducibility in a multiprocessor system
Bellofatto, Ralph A; Chen, Dong; Coteus, Paul W; Eisley, Noel A; Gara, Alan; Gooding, Thomas M; Haring, Rudolf A; Heidelberger, Philip; Kopcsay, Gerard V; Liebsch, Thomas A; Ohmacht, Martin; Reed, Don D; Senger, Robert M; Steinmacher-Burow, Burkhard; Sugawara, Yutaka
2013-11-26
Fixing a problem is usually greatly aided if the problem is reproducible. To ensure reproducibility of a multiprocessor system, the following aspects are proposed; a deterministic system start state, a single system clock, phase alignment of clocks in the system, system-wide synchronization events, reproducible execution of system components, deterministic chip interfaces, zero-impact communication with the system, precise stop of the system and a scan of the system state.
Trillo, Cristina; Doval, Angel F; Mendoza-Santoyo, Fernando; Pérez-López, Carlos; de la Torre-Ibarra, Manuel; Deán, J Luis
2009-09-28
The combination of a high-speed TV holography system and a 3D Fourier-transform data processing is proposed for the analysis of multimode vibrations in plates. The out-of-plane displacement of the object under generic vibrational excitation is resolved in time by the fast acquisition rate of a high-speed camera, and recorded in a sequence of interferograms with spatial carrier. A full-field temporal history of the multimode vibration is thus obtained. The optical phase of the interferograms is extracted and subtracted from the phase of a reference state to yield a sequence of optical phase-change maps. Each map represents the change undergone by the object between any given state and the reference state. The sequence of maps is a 3D array of data (two spatial dimensions plus time) that is processed with a 3D Fourier-transform algorithm. The individual vibration modes are separated in the 3D frequency space due to their different vibration frequencies and, to a lesser extent, to the different spatial frequencies of the mode shapes. The contribution of each individual mode (or indeed the superposition of several modes) to the dynamic behaviour of the object can then be separated by means of a bandpass filter (or filters). The final output is a sequence of complex-valued maps that contain the full-field temporal history of the selected mode (or modes) in terms of its mechanical amplitude and phase. The proof-of-principle of the technique is demonstrated with a rectangular, fully clamped, thin metal plate vibrating simultaneously in several of its natural resonant frequencies under white-noise excitation.
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.
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.
Predicting Statistical Distributions of Footbridge Vibrations
DEFF Research Database (Denmark)
Pedersen, Lars; Frier, Christian
2009-01-01
The paper considers vibration response of footbridges to pedestrian loading. Employing Newmark and Monte Carlo simulation methods, a statistical distribution of bridge vibration levels is calculated modelling walking parameters such as step frequency and stride length as random variables...
International Nuclear Information System (INIS)
Michaelides, P G; Apostolellis, P G; Fassois, S D
2011-01-01
Vibration-based damage detection and identification in a laboratory cable-stayed bridge model is addressed under inherent, environmental, and experimental uncertainties. The problem is challenging as conventional stochastic methods face difficulties due to uncertainty underestimation. A novel method is formulated based on identified Random Coefficient Pooled ARX (RCP-ARX) representations of the dynamics and statistical hypothesis testing. The method benefits from the ability of RCP models in properly capturing uncertainty. Its effectiveness is demonstrated via a high number of experiments under a variety of damage scenarios.
Energy Technology Data Exchange (ETDEWEB)
Michaelides, P G; Apostolellis, P G; Fassois, S D, E-mail: mixail@mech.upatras.gr, E-mail: fassois@mech.upatras.gr [Laboratory for Stochastic Mechanical Systems and Automation (SMSA), Department of Mechanical and Aeronautical Engineering, University of Patras, GR 265 00 Patras (Greece)
2011-07-19
Vibration-based damage detection and identification in a laboratory cable-stayed bridge model is addressed under inherent, environmental, and experimental uncertainties. The problem is challenging as conventional stochastic methods face difficulties due to uncertainty underestimation. A novel method is formulated based on identified Random Coefficient Pooled ARX (RCP-ARX) representations of the dynamics and statistical hypothesis testing. The method benefits from the ability of RCP models in properly capturing uncertainty. Its effectiveness is demonstrated via a high number of experiments under a variety of damage scenarios.
Directory of Open Access Journals (Sweden)
Dwi Priyanta
2016-12-01
Full Text Available Subsea pipeline is a transportation infrastructure of oil and gas as an alternative for ship tanker. The uneven topography surface of the sea floor resulting the pipe undergoes free span. The free span is a condition endured by the pipe where the pipe position has distance or gap with the seabed supported by two pivot. The free span is at risk of experiencing a vibration caused by the presence of dynamic load that is current and the wave. The vibration that occurs is the impact of the presence of the phenomenon of Vortex Induced Vibration (VIV. The Phenomenon Of VIV occur on a cylindrical component caused by ocean currents, causing the occurrence of vibration by the movement of fluid on the pipe so that it raises the vortex at the rear of the direction of oncoming flow. One way to dampen or reduce the impact of VIV is by adding suppresion device. VIV suppression device is a tool that is installed on the pipeline on offshore piping installationcthat serves to dampen or reduce the impact of VIV. One of the simulations used to know the characteristics of a fluid is to use (CFD Computational Fluid Dynamic. With the addition of suppression device can add the rest of the operating time on a free span of affected VIV, on the condition of free span critical exposed VIV (Vortex Induced Vibration value has a life time on plain pipe 44.21 years, on pipe with 53.09 years and Fairing on the pipe with the Helical strike 52.95 year.
Shahidha, R; Al-Saadi, Abdulaziz A; Muthu, S
2015-01-05
The FTIR (4000-400 cm(-1)), FT-Raman (4000-100 cm(-1)) and UV-Visible (400-200 nm) spectra of midodrine were recorded in the condensed state. The complete vibrational frequencies, optimized geometry, intensity of vibrational bands and atomic charges were obtained by using Density Functional Theory (DFT) with the help of 6-311++G(d,p) basis set. The first order hyperpolarizability (β) and related properties (μ, α and Δα) of this molecular system were calculated by using DFT/6-311++G(d,p) method based on the finite-field approach. The assignments of the vibrational spectra have been carried out with the help of Normal Co-ordinate Analysis (NCA) following the scaled quantum mechanical force methodology. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using NBO analysis. From the recorded UV-Visible spectrum, the electronic properties such as excitation energies, oscillator strength and wavelength are calculated by DFT in water and gas methods using 6-311++G(d,p) basis set. The calculated HOMO and LUMO energies confirm that charge transfer occurs within the molecule. Besides MEP, NLO and thermodynamic properties were also calculated and interpreted. The electron density-based local reactivity descriptor such as Fukui functions was calculated to explain the chemical selectivity or reactivity site in midodrine. Copyright © 2014 Elsevier B.V. All rights reserved.
JANG, G. H.; LEE, S. H.; JUNG, M. S.
2002-03-01
Free vibration of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft is analyzed by using Hamilton's principle, FEM and substructure synthesis. The spinning disk is described by using the Kirchhoff plate theory and von Karman non-linear strain. The rotating spindle and stationary shaft are modelled by Rayleigh beam and Euler beam respectively. Using Hamilton's principle and including the rigid body translation and tilting motion, partial differential equations of motion of the spinning flexible disk and spindle are derived consistently to satisfy the geometric compatibility in the internal boundary between substructures. FEM is used to discretize the derived governing equations, and substructure synthesis is introduced to assemble each component of the disk-spindle-bearing-shaft system. The developed method is applied to the spindle system of a computer hard disk drive with three disks, and modal testing is performed to verify the simulation results. The simulation result agrees very well with the experimental one. This research investigates critical design parameters in an HDD spindle system, i.e., the non-linearity of a spinning disk and the flexibility and boundary condition of a stationary shaft, to predict the free vibration characteristics accurately. The proposed method may be effectively applied to predict the vibration characteristics of a spinning flexible disk-spindle system supported by ball bearing and flexible shaft in the various forms of computer storage device, i.e., FDD, CD, HDD and DVD.
Reproducibility of scoring emphysema by HRCT
International Nuclear Information System (INIS)
Malinen, A.; Partanen, K.; Rytkoenen, H.; Vanninen, R.; Erkinjuntti-Pekkanen, R.
2002-01-01
Purpose: We evaluated the reproducibility of three visual scoring methods of emphysema and compared these methods with pulmonary function tests (VC, DLCO, FEV1 and FEV%) among farmer's lung patients and farmers. Material and Methods: Three radiologists examined high-resolution CT images of farmer's lung patients and their matched controls (n=70) for chronic interstitial lung diseases. Intraobserver reproducibility and interobserver variability were assessed for three methods: severity, Sanders' (extent) and Sakai. Pulmonary function tests as spirometry and diffusing capacity were measured. Results: Intraobserver -values for all three methods were good (0.51-0.74). Interobserver varied from 0.35 to 0.72. The Sanders' and the severity methods correlated strongly with pulmonary function tests, especially DLCO and FEV1. Conclusion: The Sanders' method proved to be reliable in evaluating emphysema, in terms of good consistency of interpretation and good correlation with pulmonary function tests
Reproducibility of scoring emphysema by HRCT
Energy Technology Data Exchange (ETDEWEB)
Malinen, A.; Partanen, K.; Rytkoenen, H.; Vanninen, R. [Kuopio Univ. Hospital (Finland). Dept. of Clinical Radiology; Erkinjuntti-Pekkanen, R. [Kuopio Univ. Hospital (Finland). Dept. of Pulmonary Diseases
2002-04-01
Purpose: We evaluated the reproducibility of three visual scoring methods of emphysema and compared these methods with pulmonary function tests (VC, DLCO, FEV1 and FEV%) among farmer's lung patients and farmers. Material and Methods: Three radiologists examined high-resolution CT images of farmer's lung patients and their matched controls (n=70) for chronic interstitial lung diseases. Intraobserver reproducibility and interobserver variability were assessed for three methods: severity, Sanders' (extent) and Sakai. Pulmonary function tests as spirometry and diffusing capacity were measured. Results: Intraobserver -values for all three methods were good (0.51-0.74). Interobserver varied from 0.35 to 0.72. The Sanders' and the severity methods correlated strongly with pulmonary function tests, especially DLCO and FEV1. Conclusion: The Sanders' method proved to be reliable in evaluating emphysema, in terms of good consistency of interpretation and good correlation with pulmonary function tests.
Vibration transducer calibration techniques
Brinkley, D. J.
1980-09-01
Techniques for the calibration of vibration transducers used in the Aeronautical Quality Assurance Directorate of the British Ministry of Defence are presented. Following a review of the types of measurements necessary in the calibration of vibration transducers, the performance requirements of vibration transducers, which can be used to measure acceleration, velocity or vibration amplitude, are discussed, with particular attention given to the piezoelectric accelerometer. Techniques for the accurate measurement of sinusoidal vibration amplitude in reference-grade transducers are then considered, including the use of a position sensitive photocell and the use of a Michelson laser interferometer. Means of comparing the output of working-grade accelerometers with that of previously calibrated reference-grade devices are then outlined, with attention given to a method employing a capacitance bridge technique and a method to be used at temperatures between -50 and 200 C. Automatic calibration procedures developed to speed up the calibration process are outlined, and future possible extensions of system software are indicated.
Calculation of ground vibration spectra from heavy military vehicles
Krylov, V. V.; Pickup, S.; McNuff, J.
2010-07-01
The demand for reliable autonomous systems capable to detect and identify heavy military vehicles becomes an important issue for UN peacekeeping forces in the current delicate political climate. A promising method of detection and identification is the one using the information extracted from ground vibration spectra generated by heavy military vehicles, often termed as their seismic signatures. This paper presents the results of the theoretical investigation of ground vibration spectra generated by heavy military vehicles, such as tanks and armed personnel carriers. A simple quarter car model is considered to identify the resulting dynamic forces applied from a vehicle to the ground. Then the obtained analytical expressions for vehicle dynamic forces are used for calculations of generated ground vibrations, predominantly Rayleigh surface waves, using Green's function method. A comparison of the obtained theoretical results with the published experimental data shows that analytical techniques based on the simplified quarter car vehicle model are capable of producing ground vibration spectra of heavy military vehicles that reproduce basic properties of experimental spectra.
Mullins, Mary M.; DeLuca, Julia B.; Crepaz, Nicole; Lyles, Cynthia M.
2018-01-01
Systematic reviews are an essential tool for researchers, prevention providers and policy makers who want to remain current with the evidence in the field. Systematic review must adhere to strict standards, as the results can provide a more objective appraisal of evidence for making scientific decisions than traditional narrative reviews. An integral component of a systematic review is the development and execution of a comprehensive systematic search to collect available and relevant information. A number of reporting guidelines have been developed to ensure quality publications of systematic reviews. These guidelines provide the essential elements to include in the review process and report in the final publication for complete transparency. We identified the common elements of reporting guidelines and examined the reporting quality of search methods in HIV behavioral intervention literature. Consistent with the findings from previous evaluations of reporting search methods of systematic reviews in other fields, our review shows a lack of full and transparent reporting within systematic reviews even though a plethora of guidelines exist. This review underscores the need for promoting the completeness of and adherence to transparent systematic search reporting within systematic reviews. PMID:26052651
2009-01-01
Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.
Suresh, S.; Gunasekaran, S.; Srinivasan, S.
2015-03-01
The solid phase FT-IR and FT-Raman spectra of 4-Hydroxy-2-methyl-N-(2-pyridinyl)-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxide (Piroxicam) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The molecular geometry, harmonic vibrational frequencies and bonding features of piroxicam in the ground state have been calculated by Hartree-Fock (HF) and density functional theory (DFT) methods using 6-311++G(d,p) basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimental obtained by FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of the title compound has been made on the basis of the calculated potential energy distribution (PED). The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MESP) are also performed. The linear polarizability (α) and the first order hyper polarizability (β) values of the title compound have been computed. The molecular stability arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.
International Nuclear Information System (INIS)
Sakai, Takaaki; Yamaguchi, Akira; Morisita, Masaki; Iwata, Koji
1998-08-01
The incident of sodium leakage from a main pipe of the secondary heat transport system of Monju fast breeder reactor was caused by the failure of a thermometer well. 'Flow-induced vibration design guide for thermometer wells' (express as 'design guide') was proposed by PNC Working Group to prevent the same cause of the sodium leak incident in future. On this report, applicability of the 'design guide' was estimated to plant conditions in high Reynolds-number(approximately 3x10 5 ∼ 3x10 6 ) involving the supercritical region, by measured data on a vortex synchronized vibration and a turbulence induced vibration. Experiments were performed for cylindrical and taper shaped types of test pieces. As results, reduced velocity (Vr) at onsets of the inline synchronized vibration were evaluated to be grater than 1.0 in the range of experimental conditions. Fluctuating drag and lift coefficients, which were evaluated from power spectrum of turbulence for Vr < 1.0 condition, were 0.01 ∼ 0.05 for drag direction and 0.04 ∼ 0.13 for lift direction. The fluctuating drag and lift coefficients used in the 'design guide' were estimated to be conservative by comparison with these data. Correlation lengths for a cylinder and a taper shaped one in the high Reynolds-number region were estimated to be 1.6 times of the diameter(D) in the maximum case. The measured value of correlation length is enough smaller than the 'design guide' value of 3.0D. Displacement amplitudes of test pieces for Vr < 1.0 conditions were enough smaller (fives times) than calculated values based on the 'design guide'. Consequently, the applicability of the design guide' was confirmed in the range of experiments involving the super critical Reynolds-number region. (author)
Directory of Open Access Journals (Sweden)
Niki Yasuo
2012-06-01
Full Text Available Abstract Background Consensus has been lacking as to how to reconstruct the posterolateral corner (PLC of the knee in patients with posterolateral instability. We describe a new reconstructive technique for PLC based on Larson's method, which reflects the physiological load-sharing pattern of the lateral collateral ligament (LCL and popliteofibular ligament (PFL. Findings Semitendinosus graft is harvested, and one limb of the graft comprises PFL and the other comprises LCL. Femoral bone tunnels for the LCL and popliteus tendon are made at their anatomical insertions. Fibular bone tunnel is prepared from the anatomical insertion of the LCL to the proximal posteromedial portion of the fibular head, which corresponds to the insertion of the PFL. The graft end for popliteus tendon is delivered into the femoral bone tunnel and secured on the medial femoral condyle. The other end for LCL is passed through the fibular tunnel from posterior to anterior. While the knee is held in 90 of flexion, the graft is secured in the fibular tunnel using a 5 mm interference screw. Then, the LCL end is passed into the femoral bone tunnel and secured at the knee in extension. Conclusions Differential tension patterns between LCL and PFL is critical when securing these graft limbs. Intrafibular fixation of the graft using a small interference screw allows us to secure these two graft limbs independently with intended tension at the intended flexion angle of the knee.
Baiardi, A.; Paoloni, L.; Barone, V.; Zakrzewski, V.G.; Ortiz, J.V.
2017-01-01
The analysis of photoelectron spectra is usually facilitated by quantum mechanical simulations. Due to the recent improvement of experimental techniques, the resolution of experimental spectra is rapidly increasing, and the inclusion of vibrational effects is usually mandatory to obtain a reliable reproduction of the spectra. With the aim of defining a robust computational protocol, a general time-independent formulation to compute different kinds of vibrationally-resolved electronic spectra has been generalized to support also photoelectron spectroscopy. The electronic structure data underlying the simulation are computed using different electron propagator approaches. In addition to the more standard approaches, a new and robust implementation of the second-order self-energy approximation of the electron propagator based on a transition operator reference (TOEP2) is presented. To validate our implementation, a series of molecules has been used as test cases. The result of the simulations shows that, for ultraviolet photoionization spectra, the more accurate non-diagonal approaches are needed to obtain a reliable reproduction of vertical ionization energies, but diagonal approaches are sufficient for energy gradients and pole strengths. For X-ray photoelectron spectroscopy, the TOEP2 approach, besides being more efficient, is also the most accurate in the reproduction of both vertical ionization energies and vibrationally-resolved bandshapes. PMID:28521087
Directory of Open Access Journals (Sweden)
Wei Xu
2016-01-01
Full Text Available Taking the underground powerhouse of a pumped storage power station as the engineering background, this study established a 3D finite element model of the main and auxiliary powerhouse and performed the dynamic harmonica calculation for its fluctuating pressure. Based on the power flow theory, the ANSYS Parametric Design Language (APDL procedure was completed to calculate the power transmission in the powerhouse. The law of dominant path recognition was first proposed to assess the structure’s dominant transmission using a numerical solution on nodes in the model. The conductivity of the closed-cell foam that filled the structure’s joints was examined, as were the dynamic transmission features of the rock around and beneath the powerhouse. The results indicated that, as a structural joint filler, closed-cell foam could actively restrict vibration transmission, and the directions of dynamic transmission were mainly perpendicular to and along the river in the foundation rock. Approximately 20 percent of the foundation rock beneath the auxiliary powerhouse was disturbed by the concrete around the spiral case and induced vibrations in the powerhouse’s lower floors. Vibration in the higher floors was derived from downstream rock, and the dynamic transmission effect had a clear advantage along the horizontal direction.
Structural Stability and Vibration
DEFF Research Database (Denmark)
Wiggers, Sine Leergaard; Pedersen, Pauli
at the University of Southern Denmark, it reports on fundamental formulas and makes uses of graphical representation to promote understanding. Thanks to the emphasis put on analytical methods and numerical results, the book is meant to make students and engineers familiar with all fundamental equations...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....
Reproducibility of somatosensory spatial perceptual maps.
Steenbergen, Peter; Buitenweg, Jan R; Trojan, Jörg; Veltink, Peter H
2013-02-01
Various studies have shown subjects to mislocalize cutaneous stimuli in an idiosyncratic manner. Spatial properties of individual localization behavior can be represented in the form of perceptual maps. Individual differences in these maps may reflect properties of internal body representations, and perceptual maps may therefore be a useful method for studying these representations. For this to be the case, individual perceptual maps need to be reproducible, which has not yet been demonstrated. We assessed the reproducibility of localizations measured twice on subsequent days. Ten subjects participated in the experiments. Non-painful electrocutaneous stimuli were applied at seven sites on the lower arm. Subjects localized the stimuli on a photograph of their own arm, which was presented on a tablet screen overlaying the real arm. Reproducibility was assessed by calculating intraclass correlation coefficients (ICC) for the mean localizations of each electrode site and the slope and offset of regression models of the localizations, which represent scaling and displacement of perceptual maps relative to the stimulated sites. The ICCs of the mean localizations ranged from 0.68 to 0.93; the ICCs of the regression parameters were 0.88 for the intercept and 0.92 for the slope. These results indicate a high degree of reproducibility. We conclude that localization patterns of non-painful electrocutaneous stimuli on the arm are reproducible on subsequent days. Reproducibility is a necessary property of perceptual maps for these to reflect properties of a subject's internal body representations. Perceptual maps are therefore a promising method for studying body representations.
Energy Technology Data Exchange (ETDEWEB)
Richard A. Corbett; Dave Severance
2005-02-01
Formicary corrosion is an insidious form of localized pitting corrosion. Notoya (1997b) wrote, ?In Japan, this type of corrosion is found in approximately 10% of cases of premature failure of copper tubes.? Attack characteristically features very small surface pits which are not visible to the un-aided eye, and random directional changes in the underlying copper metal. Attack is rapid. Failures have occurred before installation, shortly thereafter, or within several years later. Objectives of this Research Project Conduct an in depth literature search on the subject of formicary corrosion. Define the corrosion mechanism. Develop a test method that will reproduce formicary corrosion. Develop a test method for screening candidate materials that could cause formicary corrosion.
Diagnostic aspects of vibration-induced white finger.
Olsen, Niels
2002-01-01
Vibration-induced white finger (VWF) is a secondary type of Raynaud's phenomenon (RP) caused by exposure to hand-arm vibration. The present review concerns the cold-provoked attack of RP in vasospastic VWF. It concentrates on the most common clinical and laboratory methods used to diagnose RP in vibration-exposed subjects. Some physiological aspects of the attack of RP are mentioned to elucidate the diagnostic principles of the tests. Anamnestic diagnostics by medical interviews and questionnaires as well as cold-provocation tests with detection of finger colour, finger systolic blood pressure (FSP), recovery time of finger skin temperature and recovery time of normal nail colour after nail compression are mentioned. The discriminative capacity and the reproducibility of the tests are discussed. Cold-provocation tests with detection of finger colour or zero FSP during cooling are recommended to be used if an attack of RP has to be registered for diagnostic or medico-legal purposes in individual cases. An abnormal reduction in FSP during cooling makes a history of RP very probable and is a suitable laboratory test for groups of subjects. Both recovery tests may be useful screening tests in field studies of vibration-exposed subject groups.
Data interpolation for vibration diagnostics using two-variable correlations
International Nuclear Information System (INIS)
Branagan, L.
1991-01-01
This paper reports that effective machinery vibration diagnostics require a clear differentiation between normal vibration changes caused by plant process conditions and those caused by degradation. The normal relationship between vibration and a process parameter can be quantified by developing the appropriate correlation. The differences in data acquisition requirements between dynamic signals (vibration spectra) and static signals (pressure, temperature, etc.) result in asynchronous data acquisition; the development of any correlation must then be based on some form of interpolated data. This interpolation can reproduce or distort the original measured quantity depending on the characteristics of the data and the interpolation technique. Relevant data characteristics, such as acquisition times, collection cycle times, compression method, storage rate, and the slew rate of the measured variable, are dependent both on the data handling and on the measured variable. Linear and staircase interpolation, along with the use of clustering and filtering, provide the necessary options to develop accurate correlations. The examples illustrate the appropriate application of these options
Molecular vibrations the theory of infrared and Raman vibrational spectra
Wilson, E Bright; Cross, Paul C
1980-01-01
Pedagogical classic and essential reference focuses on mathematics of detailed vibrational analyses of polyatomic molecules, advancing from application of wave mechanics to potential functions and methods of solving secular determinant.
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
Huang, Ya; Ferguson, Neil S.
2018-04-01
The study implements a classic signal analysis technique, typically applied to structural dynamics, to examine the nonlinear characteristics seen in the apparent mass of a recumbent person during whole-body horizontal random vibration. The nonlinearity in the present context refers to the amount of 'output' that is not correlated or coherent to the 'input', usually indicated by values of the coherence function that are less than unity. The analysis is based on the longitudinal horizontal inline and vertical cross-axis apparent mass of twelve human subjects exposed to 0.25-20 Hz random acceleration vibration at 0.125 and 1.0 ms-2 r.m.s. The conditioned reverse path frequency response functions (FRF) reveal that the uncorrelated 'linear' relationship between physical input (acceleration) and outputs (inline and cross-axis forces) has much greater variation around the primary resonance frequency between 0.5 and 5 Hz. By reversing the input and outputs of the physical system, it is possible to assemble additional mathematical inputs from the physical output forces and mathematical constructs (e.g. square root of inline force). Depending on the specific construct, this can improve the summed multiple coherence at frequencies where the response magnitude is low. In the present case this is between 6 and 20 Hz. The statistical measures of the response force time histories of each of the twelve subjects indicate that there are potential anatomical 'end-stops' for the sprung mass in the inline axis. No previous study has applied this reverse path multi-input-single-output approach to human vibration kinematic and kinetic data before. The implementation demonstrated in the present study will allow new and existing data to be examined using this different analytical tool.
Reproducibility in Computational Neuroscience Models and Simulations
McDougal, Robert A.; Bulanova, Anna S.; Lytton, William W.
2016-01-01
Objective Like all scientific research, computational neuroscience research must be reproducible. Big data science, including simulation research, cannot depend exclusively on journal articles as the method to provide the sharing and transparency required for reproducibility. Methods Ensuring model reproducibility requires the use of multiple standard software practices and tools, including version control, strong commenting and documentation, and code modularity. Results Building on these standard practices, model sharing sites and tools have been developed that fit into several categories: 1. standardized neural simulators, 2. shared computational resources, 3. declarative model descriptors, ontologies and standardized annotations; 4. model sharing repositories and sharing standards. Conclusion A number of complementary innovations have been proposed to enhance sharing, transparency and reproducibility. The individual user can be encouraged to make use of version control, commenting, documentation and modularity in development of models. The community can help by requiring model sharing as a condition of publication and funding. Significance Model management will become increasingly important as multiscale models become larger, more detailed and correspondingly more difficult to manage by any single investigator or single laboratory. Additional big data management complexity will come as the models become more useful in interpreting experiments, thus increasing the need to ensure clear alignment between modeling data, both parameters and results, and experiment. PMID:27046845
International Nuclear Information System (INIS)
Solomonik, V.G.; Marochko, O.Yu.
2000-01-01
Structure and vibrational spectra of MHal 3 molecules (M = Sc, Y, La, Lu; Hal = F, Cl, Br, I) are studied by the CISD+Q method. It is ascertained that equilibrium configuration of nuclei in all the molecules, except LaF 3 , is plane (D 3h symmetry), while that of LaF 3 molecule - pyramidal (C 3c symmetry). Results of the calculations are compared with previously published experimental data. Band reference in IR spectra of ScBr 3 , YF 3 and YCl 3 molecules has been corrected [ru
International Nuclear Information System (INIS)
Adrian, H.
1981-01-01
The influence of crystal defects on the phonon spectra was studied for fcc lead using superconducting tunneling spectroscopy. The theory predicts low frequency modes for the vibrational states of interstitials in (100) dumbbell configuration. Low temperature irradiation of superconducting point contacts with fast ions (point contact thickness small compared to the average ion range) showed radiation-induced structures in the low-energy part of the Eliashberg function for lead. These resonant modes are reduced by annealing at 18.5 K; they are attributed to small interstitial clusters. The radiation-induced structures are completely removed by room temperature annealing. (orig.)
Vibrational frame transformation for electron-molecule scattering
International Nuclear Information System (INIS)
Greene, C.H.; Jungen, C.
1985-01-01
The frame-transformation theory of electron interaction with a vibrating diatomic core is extended to allow for energy dependence of its parameters. The Born-Oppenheimer separation of electron and nuclear motion is preserved when the electron penetrates the molecular core. The extended theory reproduces the boomerang-model treatment of vibrational excitation in resonant e-N 2 collisions
Energy Technology Data Exchange (ETDEWEB)
Lewis, Nicholas H. C.; Dong, Hui; 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, California 94720 (United States); Kavli Energy Nanosciences Institute at Berkeley, Berkeley, California 94720 (United States)
2015-09-28
Two dimensional electronic spectroscopy has proved to be a valuable experimental technique to reveal electronic excitation dynamics in photosynthetic pigment-protein complexes, nanoscale semiconductors, organic photovoltaic materials, and many other types of systems. It does not, however, provide direct information concerning the spatial structure and dynamics of excitons. 2D infrared spectroscopy has become a widely used tool for studying structural dynamics but is incapable of directly providing information concerning electronic excited states. 2D electronic-vibrational (2DEV) spectroscopy provides a link between these domains, directly connecting the electronic excitation with the vibrational structure of the system under study. In this work, we derive response functions for the 2DEV spectrum of a molecular dimer and propose a method by which 2DEV spectra could be used to directly measure the electronic site populations as a function of time following the initial electronic excitation. We present results from the response function simulations which show that our proposed approach is substantially valid. This method provides, to our knowledge, the first direct experimental method for measuring the electronic excited state dynamics in the spatial domain, on the molecular scale.
Completely reproducible description of digital sound data with cellular automata
International Nuclear Information System (INIS)
Wada, Masato; Kuroiwa, Jousuke; Nara, Shigetoshi
2002-01-01
A novel method of compressive and completely reproducible description of digital sound data by means of rule dynamics of CA (cellular automata) is proposed. The digital data of spoken words and music recorded with the standard format of a compact disk are reproduced completely by this method with use of only two rules in a one-dimensional CA without loss of information
Directory of Open Access Journals (Sweden)
David Camarena-Martinez
2016-01-01
Full Text Available For industry, the induction motors are essential elements in production chains. Despite the robustness of induction motors, they are susceptible to failures. The broken rotor bar (BRB fault in induction motors has received special attention since one of its characteristics is that the motor can continue operating with apparent normality; however, at certain point the fault may cause severe damage to the motor. In this work, a methodology to detect BRBs using vibration signals is proposed. The methodology uses the Shannon entropy to quantify the amount of information provided by the vibration signals, which changes due to the presence of new frequency components associated with the fault. For automatic diagnosis, the K-means cluster algorithm and a decision-making unit that looks for the nearest cluster through the Euclidian distance are applied. Unlike other reported works, the proposal can diagnose the BRB condition during startup transient and steady state regimes of operation. Additionally, the proposal is also implemented into a field programmable gate array in order to offer a low-cost and low-complex online monitoring system. The obtained results demonstrate the proposal effectiveness to diagnose half, one, and two BRBs.
Covington, Cody L; Nicu, Valentin P; Polavarapu, Prasad L
2015-10-22
Quantum chemical (QC) predictions of vibrational circular dichroism (VCD) spectra for the keto form of 3-benzoylcamphor and conformationally flexible diacetates of spiroindicumide A and B are presented. The exciton chirality (EC) model has been briefly reviewed, and a procedure to evaluate the relevance of the EC model has been presented. The QC results are compared with literature experimental VCD spectra as well as with those obtained using the EC model for VCD. These comparisons reveal that the EC contributions to bisignate VCD couplets associated with the C═O stretching vibrations of benzoylcamphor, spiroindicumide A diacetate, and spiroindicumide B diacetate are only ∼30%, ∼3%, and ∼15%, respectively. With such meager EC contributions, the correct absolute configurations (ACs) suggested in the literature for spiroindicumide A diacetate and spiroindicumide B diacetate molecules using the EC concepts can be considered fortuitous. The possibilities for obtaining wrong AC predictions using the EC concepts for VCD are identified, and guidelines for the future use of this model are presented.
International Nuclear Information System (INIS)
Streicher, V.; Jax, P.; Ruthrof, K.
1987-01-01
This paper deals with three stand-alone-systems as an aid to check the mechanical integrity of the primary circuit of nuclear power plants. The main goals of these systems are early detection of faults and malfunctions, the facilitation of fault clearance, the avoidance of sequential damage and reduction of inspection time and cost. Obviously the proper application of the systems as well as the measures they induce and make possible increase the availability of the plant and contribute to lifetime extension. In order to detect, identify and pinpoint the changes in component structure such as loosened connections, broken parts or components, loose or loosened particles, fatigued materials, cracks and leaks, specialized monitoring systems were developed by KWU (Kraftwerk Union AG) during the last ten years. Requirements concerning vibration, loose parts and leakage monitoring are part of German guidelines and safety standards. Therefore systems for these applications are implemented in most of the nuclear power plants in Western Germany. This paper presents newly developed, microprocessor-based systems for loose parts monitoring, vibration monitoring and leakage monitoring and also includes specific case histories for the different topics
Guidelines for Reproducibly Building and Simulating Systems Biology Models.
Medley, J Kyle; Goldberg, Arthur P; Karr, Jonathan R
2016-10-01
Reproducibility is the cornerstone of the scientific method. However, currently, many systems biology models cannot easily be reproduced. This paper presents methods that address this problem. We analyzed the recent Mycoplasma genitalium whole-cell (WC) model to determine the requirements for reproducible modeling. We determined that reproducible modeling requires both repeatable model building and repeatable simulation. New standards and simulation software tools are needed to enhance and verify the reproducibility of modeling. New standards are needed to explicitly document every data source and assumption, and new deterministic parallel simulation tools are needed to quickly simulate large, complex models. We anticipate that these new standards and software will enable researchers to reproducibly build and simulate more complex models, including WC models.
Smart accelerometer. [vibration damage detection
Bozeman, Richard J., Jr. (Inventor)
1994-01-01
The invention discloses methods and apparatus for detecting vibrations from machines which indicate an impending malfunction for the purpose of preventing additional damage and allowing for an orderly shutdown or a change in mode of operation. The method and apparatus is especially suited for reliable operation in providing thruster control data concerning unstable vibration in an electrical environment which is typically noisy and in which unrecognized ground loops may exist.
Vibrational Spectral Studies of Gemfibrozil
Benitta, T. Asenath; Balendiran, G. K.; James, C.
2008-11-01
The Fourier Transform Raman and infrared spectra of the crystallized drug molecule 5-(2,5-Dimethylphenoxy)-2,2-dimethylpentanoic acid (Gemfibrozil) have been recorded and analyzed. Quantum chemical computational methods have been employed using Gaussian 03 software package based on Hartree Fock method for theoretically modeling the grown molecule. The optimized geometry and vibrational frequencies have been predicted. Observed vibrational modes have been assigned with the aid of normal coordinate analysis.
PREFACE: Vibrations at surfaces Vibrations at surfaces
Rahman, Talat S.
2011-12-01
This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of
Tool-specific performance of vibration-reducing gloves for attenuating fingers-transmitted vibration
Welcome, Daniel E.; Dong, Ren G.; Xu, Xueyan S.; Warren, Christopher; McDowell, Thomas W.
2016-01-01
BACKGROUND Fingers-transmitted vibration can cause vibration-induced white finger. The effectiveness of vibration-reducing (VR) gloves for reducing hand transmitted vibration to the fingers has not been sufficiently examined. OBJECTIVE The objective of this study is to examine tool-specific performance of VR gloves for reducing finger-transmitted vibrations in three orthogonal directions (3D) from powered hand tools. METHODS A transfer function method was used to estimate the tool-specific effectiveness of four typical VR gloves. The transfer functions of the VR glove fingers in three directions were either measured in this study or during a previous study using a 3D laser vibrometer. More than seventy vibration spectra of various tools or machines were used in the estimations. RESULTS When assessed based on frequency-weighted acceleration, the gloves provided little vibration reduction. In some cases, the gloves amplified the vibration by more than 10%, especially the neoprene glove. However, the neoprene glove did the best when the assessment was based on unweighted acceleration. The neoprene glove was able to reduce the vibration by 10% or more of the unweighted vibration for 27 out of the 79 tools. If the dominant vibration of a tool handle or workpiece was in the shear direction relative to the fingers, as observed in the operation of needle scalers, hammer chisels, and bucking bars, the gloves did not reduce the vibration but increased it. CONCLUSIONS This study confirmed that the effectiveness for reducing vibration varied with the gloves and the vibration reduction of each glove depended on tool, vibration direction to the fingers, and finger location. VR gloves, including certified anti-vibration gloves do not provide much vibration reduction when judged based on frequency-weighted acceleration. However, some of the VR gloves can provide more than 10% reduction of the unweighted vibration for some tools or workpieces. Tools and gloves can be matched for
Mıhçıokur, Özlem; Özpozan, Talat
2017-12-01
Oxindole and its derivatives have wide applications in different industries such as in synthetic & natural fibers, dyes for hair and plastic materials in addition to their biological importance. In the present study, one of the oxindole derivatives, N-(2-diethylaminoethyl)-5-[(Z)-(5-fluoro-2-oxo-1H-indol-3-ylidene)methyl]-2,4-dimethyl-1H-pyrrole-3-carboxamide (Sunitinib), which is used as an anti-cancer drug, was investigated in terms of structural, vibrational spectroscopic and theoretical analysis. The calculations have been performed for gaseous, aqueous and DMSO phases, respectively. Potential Energy Surface (PES) scan has been carrried out to obtain the most stable structures of all the phases of the title molecule using B3LYP/6-31G(d,p) level and the geometrical variations among them are discussed. The solvent effect for Sunitinib in aqueous and DMSO phases have been performed by means of the self-consistent recognition reaction field (SCRF) method as implemented in the integral equation formalism polarized continuum model (IEFPCM). On the other hand, NBO analysis has been carried out to understand probable hydrogen bonding sites and charge transfers. Additionally, the HOMO and the LUMO energies are calculated using B3LYP/6-31G(d,p) to determine the intra molecular charge transfers (ICT) within the molecule and the kinetic stabilities for each phases. The molecular electrostatic potential surface (MESP) has been plotted over the optimized structure to estimate the reactive sites of electrophilic and nucleophilic attacks regarding Sunitinib molecule. The potential energy distribution (PED) has been calculated using VEDA4 program and vibrational assignments of the experimental spectra (IR & Raman) have been elucidated by means of the calculated vibrational spectra. The observed vibrational spectra of Sunitinib is compared with the calculated spectra obtained by using B3LYP functional both with 6-31G(d,p) and 6-311++G(d,p) basis sets. Theoretical results
Reproducible Bioinformatics Research for Biologists
This book chapter describes the current Big Data problem in Bioinformatics and the resulting issues with performing reproducible computational research. The core of the chapter provides guidelines and summaries of current tools/techniques that a noncomputational researcher would need to learn to pe...
Reproducibility of brain ADC histograms
International Nuclear Information System (INIS)
Steens, S.C.A.; Buchem, M.A. van; Admiraal-Behloul, F.; Schaap, J.A.; Hoogenraad, F.G.C.; Wheeler-Kingshott, C.A.M.; Tofts, P.S.; Cessie, S. le
2004-01-01
The aim of this study was to assess the effect of differences in acquisition technique on whole-brain apparent diffusion coefficient (ADC) histogram parameters, as well as to assess scan-rescan reproducibility. Diffusion-weighted imaging (DWI) was performed in 7 healthy subjects with b-values 0-800, 0-1000, and 0-1500 s/mm 2 and fluid-attenuated inversion recovery (FLAIR) DWI with b-values 0-1000 s/mm 2 . All sequences were repeated with and without repositioning. The peak location, peak height, and mean ADC of the ADC histograms and mean ADC of a region of interest (ROI) in the white matter were compared using paired-sample t tests. Scan-rescan reproducibility was assessed using paired-sample t tests, and repeatability coefficients were reported. With increasing maximum b-values, ADC histograms shifted to lower values, with an increase in peak height (p<0.01). With FLAIR DWI, the ADC histogram shifted to lower values with a significantly higher, narrower peak (p<0.01), although the ROI mean ADC showed no significant differences. For scan-rescan reproducibility, no significant differences were observed. Different DWI pulse sequences give rise to different ADC histograms. With a given pulse sequence, however, ADC histogram analysis is a robust and reproducible technique. Using FLAIR DWI, the partial-voluming effect of cerebrospinal fluid, and thus its confounding effect on histogram analyses, can be reduced
Directory of Open Access Journals (Sweden)
Hao Jin
2015-01-01
Full Text Available Steel-spring floating slab tracks are one of the most effective methods to reduce vibrations from underground railways, which has drawn more and more attention in scientific communities. In this paper, the steel-spring floating slab track located in Track Vibration Abatement and Control Laboratory was modeled with four-pole parameter method. The influences of the fastener damping ratio, the fastener stiffness, the steel-spring damping ratio, and the steel-spring stiffness were researched for the rail displacement and the foundation acceleration. Results show that the rail displacement and the foundation acceleration will decrease with the increase of the fastener stiffness or the steel-spring damping ratio. However, the rail displacement and the foundation acceleration have the opposite variation tendency for the fastener damping ratio and the steel-spring stiffness. In order to optimize the rail displacement and the foundation acceleration affected by the fastener damping ratio and the steel-spring stiffness at the same time, a multiobjective ant colony optimization (ACO was employed. Eventually, Pareto optimal frontier of the rail displacement and the foundation acceleration was derived. Furthermore, the desirable values of the fastener damping ratio and the steel-spring stiffness can be obtained according to the corresponding Pareto optimal solution set.
Directory of Open Access Journals (Sweden)
Shui-Ting Zhou
2017-01-01
Full Text Available This study is about the impact of the performance and the sensitivity analysis for parameters of the torsion bar suspension in the electric sight-seeing car, which the authors’ laboratory designed and which is used in the authors’ university. The suspension stiffness was calculated by using the virtual work principle, the vector algebra, and tensor of finite rotation methods and was verified by the ADAMS software. Based on the random vibration analysis method, the paper analyzed the dynamic tire load (DTL, suspension working space (SWS, and comfort performance parameters. For the purpose of decreasing the displacement of the suspension and limiting the frequency of impacting the stop block, the paper examined the three parameters and optimized the basic parameters of the torsion bar. The results show that the method achieves a great effect and contributes an accurate value for the general layout design.
Vibration isolation of a ship's seat
Agahi, Maryam; Samani, Mehrdad B.; Behzad, Mehdi
2005-05-01
Different factors cause vibration. These vibrations make the voyages difficult and reduce comfort and convenience in passenger ships. In this paper, the creating factors of vibration have discussed first, then with mathematical modelling it will be attempted to minimize the vibration over the crew's seat. The modelling consists of a system with two degrees of freedom and by using vibrationisolation with passive method of Tuned Mass Damper (TMD) it will be tried to reduce the vibration over personnel. Moreover using active control systems will be compared with passive systems.
Barnette, Anna L; Lee, Christopher; Bradley, Laura C; Schreiner, Edward P; Park, Yong Bum; Shin, Heenae; Cosgrove, Daniel J; Park, Sunkyu; Kim, Seong H
2012-07-01
The non-centrosymmetry requirement of sum frequency generation (SFG) vibration spectroscopy allows the detection and quantification of crystalline cellulose in lignocellulose biomass without spectral interferences from hemicelluloses and lignin. This paper shows a correlation between the amount of crystalline cellulose in biomass and the SFG signal intensity. Model biomass samples were prepared by mixing commercially available cellulose, xylan, and lignin to defined concentrations. The SFG signal intensity was found sensitive to a wide range of crystallinity, but varied non-linearly with the mass fraction of cellulose in the samples. This might be due to the matrix effects such as light scattering and absorption by xylan and lignin, as well as the non-linear density dependence of the SFG process itself. Comparison with other techniques such as XRD, FT-Raman, FT-IR and NMR demonstrate that SFG can be a complementary and sensitive tool to assess crystalline cellulose in biomass. Copyright © 2012 Elsevier Ltd. All rights reserved.
ITK: Enabling Reproducible Research and Open Science
Directory of Open Access Journals (Sweden)
Matthew Michael McCormick
2014-02-01
Full Text Available Reproducibility verification is essential to the practice of the scientific method. Researchers report their findings, which are strengthened as other independent groups in the scientific community share similar outcomes. In the many scientific fields where software has become a fundamental tool for capturing and analyzing data, this requirement of reproducibility implies that reliable and comprehensive software platforms and tools should be made available to the scientific community. The tools will empower them and the public to verify, through practice, the reproducibility of observations that are reported in the scientific literature.Medical image analysis is one of the fields in which the use of computational resources, both software and hardware, are an essential platform for performing experimental work. In this arena, the introduction of the Insight Toolkit (ITK in 1999 has transformed the field and facilitates its progress by accelerating the rate at which algorithmic implementations are developed, tested, disseminated and improved. By building on the efficiency and quality of open source methodologies, ITK has provided the medical image community with an effective platform on which to build a daily workflow that incorporates the true scientific practices of reproducibility verification.This article describes the multiple tools, methodologies, and practices that the ITK community has adopted, refined, and followed during the past decade, in order to become one of the research communities with the most modern reproducibility verification infrastructure. For example, 207 contributors have created over 2400 unit tests that provide over 84% code line test coverage. The Insight Journal, an open publication journal associated with the toolkit, has seen over 360,000 publication downloads. The median normalized closeness centrality, a measure of knowledge flow, resulting from the distributed peer code review system was high, 0.46.
Reproducibility between conventional and digital periapical radiography for bone height measurement
Directory of Open Access Journals (Sweden)
Miguel Simancas Pallares
2015-10-01
Conclusions. Reproducibility between methods was considered poor, including subgroup analysis, therefore, reproducibility between methods is minimal. Usage of these methods in periodontics should be made implementing the whole knowledge of the technical features and the advantages of these systems.
Stochastic many-body perturbation theory for anharmonic molecular vibrations
Energy Technology Data Exchange (ETDEWEB)
Hermes, Matthew R. [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); Hirata, So, E-mail: sohirata@illinois.edu [Department of Chemistry, University of Illinois at Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801 (United States); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan)
2014-08-28
A new quantum Monte Carlo (QMC) method for anharmonic vibrational zero-point energies and transition frequencies is developed, which combines the diagrammatic vibrational many-body perturbation theory based on the Dyson equation with Monte Carlo integration. The infinite sums of the diagrammatic and thus size-consistent first- and second-order anharmonic corrections to the energy and self-energy are expressed as sums of a few m- or 2m-dimensional integrals of wave functions and a potential energy surface (PES) (m is the vibrational degrees of freedom). Each of these integrals is computed as the integrand (including the value of the PES) divided by the value of a judiciously chosen weight function evaluated on demand at geometries distributed randomly but according to the weight function via the Metropolis algorithm. In this way, the method completely avoids cumbersome evaluation and storage of high-order force constants necessary in the original formulation of the vibrational perturbation theory; it furthermore allows even higher-order force constants essentially up to an infinite order to be taken into account in a scalable, memory-efficient algorithm. The diagrammatic contributions to the frequency-dependent self-energies that are stochastically evaluated at discrete frequencies can be reliably interpolated, allowing the self-consistent solutions to the Dyson equation to be obtained. This method, therefore, can compute directly and stochastically the transition frequencies of fundamentals and overtones as well as their relative intensities as pole strengths, without fixed-node errors that plague some QMC. It is shown that, for an identical PES, the new method reproduces the correct deterministic values of the energies and frequencies within a few cm{sup −1} and pole strengths within a few thousandths. With the values of a PES evaluated on the fly at random geometries, the new method captures a noticeably greater proportion of anharmonic effects.
Reproducibility in cyclostratigraphy: initiating an intercomparison project
Sinnesael, Matthias; De Vleeschouwer, David; Zeeden, Christian; Claeys, Philippe
2017-04-01
The study of astronomical climate forcing and the application of cyclostratigraphy have experienced a spectacular growth over the last decades. In the field of cyclostratigraphy a broad range in methodological approaches exist. However, comparative study between the different approaches is lacking. Different cases demand different approaches, but with the growing importance of the field, questions arise about reproducibility, uncertainties and standardization of results. The radioisotopic dating community, in particular, has done far-reaching efforts to improve reproducibility and intercomparison of radioisotopic dates and their errors. To satisfy this need in cyclostratigraphy, we initiate a comparable framework for the community. The aims are to investigate and quantify reproducibility of, and uncertainties related to cyclostratigraphic studies and to provide a platform to discuss the merits and pitfalls of different methodologies, and their applicabilities. With this poster, we ask the feedback from the community on how to design this comparative framework in a useful, meaningful and productive manner. In parallel, we would like to discuss how reproducibility should be tested and what uncertainties should stand for in cyclostratigraphy. On the other hand, we intend to trigger interest for a cyclostratigraphic intercomparison project. This intercomparison project would imply the analysis of artificial and genuine geological records by individual researchers. All participants would be free to determine their method of choice. However, a handful of criterions will be required for an outcome to be comparable. The different results would be compared (e.g. during a workshop or a special session), and the lessons learned from the comparison could potentially be reported in a review paper. The aim of an intercomparison project is not to rank the different methods according to their merits, but to get insight into which specific methods are most suitable for which
Directory of Open Access Journals (Sweden)
Gbeminiyi Sobamowo
2017-04-01
Full Text Available The development of mathematical models for describing the dynamic behaviours of fluid conveying pipes, micro-pipes and nanotubes under the influence of some thermo-mechanical parameters results into nonlinear equations that are very difficult to solve analytically. In cases where the exact analytical solutions are presented either in implicit or explicit forms, high skills and rigorous mathematical analyses were employed. It is noted that such solutions do not provide general exact solutions. Inevitably, comparatively simple, flexible yet accurate and practicable solutions are required for the analyses of these structures. Therefore, in this study, approximate analytical solutions are provided to the nonlinear equations arising in flow-induced vibration of pipes, micro-pipes and nanotubes using Galerkin-Newton-Harmonic Method (GNHM. The developed approximate analytical solutions are shown to be valid for both small and large amplitude oscillations. The accuracies and explicitness of these solutions were examined in limiting cases to establish the suitability of the method.
International Nuclear Information System (INIS)
Chen, S.S.
1975-06-01
Several mathematical models have been proposed for calculating fuel rod responses in axial flows based on a single rod consideration. The spacing between fuel rods in liquid metal fast breeder reactors is small; hence fuel rods will interact with one another due to fluid coupling. The objective of this paper is to study the coupled vibration of fuel bundles. To account for the fluid coupling, a computer code, AMASS, is developed to calculate added mass coefficients for a group of circular cylinders based on the potential flow theory. The equations of motion for rod bundles are then derived including hydrodynamic forces, drag forces, fluid pressure, gravity effect, axial tension, and damping. Based on the equations, a method of analysis is presented to study the free and forced vibrations of rod bundles. Finally, the method is applied to a typical LMFBR fuel bundle consisting of seven rods
Reproducibility of a reaming test
DEFF Research Database (Denmark)
Pilny, Lukas; Müller, Pavel; De Chiffre, Leonardo
2012-01-01
The reproducibility of a reaming test was analysed to document its applicability as a performance test for cutting fluids. Reaming tests were carried out on a drilling machine using HSS reamers. Workpiece material was an austenitic stainless steel, machined using 4.75 m∙min-1 cutting speed and 0......). Process reproducibility was assessed as the ability of different operators to ensure a consistent rating of individual lubricants. Absolute average values as well as experimental standard deviations of the evaluation parameters were calculated, and uncertainty budgeting was performed. Results document...... a built-up edge occurrence hindering a robust evaluation of cutting fluid performance, if the data evaluation is based on surface finish only. Measurements of hole geometry provide documentation to recognize systematic error distorting the performance test....
Reproducibility of a reaming test
DEFF Research Database (Denmark)
Pilny, Lukas; Müller, Pavel; De Chiffre, Leonardo
2014-01-01
The reproducibility of a reaming test was analysed to document its applicability as a performance test for cutting fluids. Reaming tests were carried out on a drilling machine using HSS reamers. Workpiece material was an austenitic stainless steel, machined using 4.75 m•min−1 cutting speed and 0......). Process reproducibility was assessed as the ability of different operators to ensure a consistent rating of individual lubricants. Absolute average values as well as experimental standard deviations of the evaluation parameters were calculated, and uncertainty budgeting was performed. Results document...... a built–up edge occurrence hindering a robust evaluation of cutting fluid performance, if the data evaluation is based on surface finish only. Measurements of hole geometry provide documentation to recognise systematic error distorting the performance test....
Vibrational Spectroscopy of Ionic Liquids.
Paschoal, Vitor H; Faria, Luiz F O; Ribeiro, Mauro C C
2017-05-24
Vibrational spectroscopy has continued use as a powerful tool to characterize ionic liquids since the literature on room temperature molten salts experienced the rapid increase in number of publications in the 1990's. In the past years, infrared (IR) and Raman spectroscopies have provided insights on ionic interactions and the resulting liquid structure in ionic liquids. A large body of information is now available concerning vibrational spectra of ionic liquids made of many different combinations of anions and cations, but reviews on this literature are scarce. This review is an attempt at filling this gap. Some basic care needed while recording IR or Raman spectra of ionic liquids is explained. We have reviewed the conceptual basis of theoretical frameworks which have been used to interpret vibrational spectra of ionic liquids, helping the reader to distinguish the scope of application of different methods of calculation. Vibrational frequencies observed in IR and Raman spectra of ionic liquids based on different anions and cations are discussed and eventual disagreements between different sources are critically reviewed. The aim is that the reader can use this information while assigning vibrational spectra of an ionic liquid containing another particular combination of anions and cations. Different applications of IR and Raman spectroscopies are given for both pure ionic liquids and solutions. Further issues addressed in this review are the intermolecular vibrations that are more directly probed by the low-frequency range of IR and Raman spectra and the applications of vibrational spectroscopy in studying phase transitions of ionic liquids.
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...
Additive Manufacturing: Reproducibility of Metallic Parts
Directory of Open Access Journals (Sweden)
Konda Gokuldoss Prashanth
2017-02-01
Full Text Available The present study deals with the properties of five different metals/alloys (Al-12Si, Cu-10Sn and 316L—face centered cubic structure, CoCrMo and commercially pure Ti (CP-Ti—hexagonal closed packed structure fabricated by selective laser melting. The room temperature tensile properties of Al-12Si samples show good consistency in results within the experimental errors. Similar reproducible results were observed for sliding wear and corrosion experiments. The other metal/alloy systems also show repeatable tensile properties, with the tensile curves overlapping until the yield point. The curves may then follow the same path or show a marginal deviation (~10 MPa until they reach the ultimate tensile strength and a negligible difference in ductility levels (of ~0.3% is observed between the samples. The results show that selective laser melting is a reliable fabrication method to produce metallic materials with consistent and reproducible properties.
Towards Reproducibility in Computational Hydrology
Hutton, Christopher; Wagener, Thorsten; Freer, Jim; Han, Dawei; Duffy, Chris; Arheimer, Berit
2017-04-01
Reproducibility is a foundational principle in scientific research. The ability to independently re-run an experiment helps to verify the legitimacy of individual findings, and evolve (or reject) hypotheses and models of how environmental systems function, and move them from specific circumstances to more general theory. Yet in computational hydrology (and in environmental science more widely) the code and data that produces published results are not regularly made available, and even if they are made available, there remains a multitude of generally unreported choices that an individual scientist may have made that impact the study result. This situation strongly inhibits the ability of our community to reproduce and verify previous findings, as all the information and boundary conditions required to set up a computational experiment simply cannot be reported in an article's text alone. In Hutton et al 2016 [1], we argue that a cultural change is required in the computational hydrological community, in order to advance and make more robust the process of knowledge creation and hypothesis testing. We need to adopt common standards and infrastructures to: (1) make code readable and re-useable; (2) create well-documented workflows that combine re-useable code together with data to enable published scientific findings to be reproduced; (3) make code and workflows available, easy to find, and easy to interpret, using code and code metadata repositories. To create change we argue for improved graduate training in these areas. In this talk we reflect on our progress in achieving reproducible, open science in computational hydrology, which are relevant to the broader computational geoscience community. In particular, we draw on our experience in the Switch-On (EU funded) virtual water science laboratory (http://www.switch-on-vwsl.eu/participate/), which is an open platform for collaboration in hydrological experiments (e.g. [2]). While we use computational hydrology as
Ramesh, Gaddam; Reddy, Byru Venkatram
2018-05-01
In this investigation, the monomeric structure is determined for picolinic and isonicotinic acids based on geometry optimization for one of the four possible conformers and intramolecular hydrogen bond of Osbnd H⋯O using density functional theory (DFT) employing B3LYP functional supplemented with 6-311++G(d,p) basis set. Using this optimized monomeric form, the dimer structure is determined based on minimum energy and length of hydrogen bonds obtained for two possible dimeric forms yielded due to head-to-tail intermolecular Osbnd H⋯N hydrogen bond (dimer 1) linkage and tail-to -tail intermolecular Osbnd H⋯O hydrogen bond (dimer 2) linkage between pyridine ring and carboxyl group. The structure parameters obtained for monomer and dimer forms are in good agreement with the experimental literature values. The vibrational assignments have been made unambiguously for all the vibrations from FTIR and FT-Raman spectra based on the potential energy distribution (PED) and eigen vectors obtained in DFT and inverse vibrational problem (IVP) computations. The rms error between the observed and scaled frequencies is 7.7 and 9.4 cm-1 for PIA and INA, respectively. A 74-element modified valence force field is derived by Wilson's GF matrix method using 58 experimental frequencies of the two molecules in overlay least-squares technique. The average error between observed and computed frequencies by this method is calculated to be 10.39 cm-1. The results of both DFT and IVP computations yielded good agreement between observed and calculated frequencies. The NLO behaviour using hyperpolarizability values; and HOMO and LUMO energies; of the two molecules are investigated by DFT. Charge density distribution and site of chemical reactivity of the molecules are studied by molecular electrostatic surface potential (MESP). Stability of the molecules arising from hyper conjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO
International Nuclear Information System (INIS)
Fesich, Thomas M.
2012-01-01
In general, technical components are loaded and stressed by forces and moments both constant and variable over time. Multi-axial stress conditions can arise as a function of the load on, and/or the geometry of, a component. Assessing the impact on stability of multi-axial stress conditions is a problem for which no generally valid solution has as yet been found, especially when loads and stresses vary over time. This is also due to the fact that the development over time of stresses can give rise to very complex stress conditions. Assessing the lifetime of power plant components subjected to complex vibration loads and stresses often is not reliable if performed by means of conventional codes and approaches, or is associated with high degrees of conservatism. The MPA AIM-Life concept developed at the Stuttgart MPA/IMWF, which is an advanced and verified strength hypothesis based on energy considerations, allows such assessments to be made more reliably, numerically efficient, and avoiding excessive conservatism. (orig.)
Hertrampf, A; Sousa, R M; Menezes, J C; Herdling, T
2016-05-30
Quality control (QC) in the pharmaceutical industry is a key activity in ensuring medicines have the required quality, safety and efficacy for their intended use. QC departments at pharmaceutical companies are responsible for all release testing of final products but also all incoming raw materials. Near-infrared spectroscopy (NIRS) and Raman spectroscopy are important techniques for fast and accurate identification and qualification of pharmaceutical samples. Tablets containing two different active pharmaceutical ingredients (API) [bisoprolol, hydrochlorothiazide] in different commercially available dosages were analysed using Raman- and NIR Spectroscopy. The goal was to define multivariate models based on each vibrational spectroscopy to discriminate between different dosages (identity) and predict their dosage (semi-quantitative). Furthermore the combination of spectroscopic techniques was investigated. Therefore, two different multiblock techniques based on PLS have been applied: multiblock PLS (MB-PLS) and sequential-orthogonalised PLS (SO-PLS). NIRS showed better results compared to Raman spectroscopy for both identification and quantitation. The multiblock techniques investigated showed that each spectroscopy contains information not present or captured with the other spectroscopic technique, thus demonstrating that there is a potential benefit in their combined use for both identification and quantitation purposes. Copyright © 2016 Elsevier B.V. All rights reserved.
Schultz, T.J.; Kotidis, P.A.; Woodroffe, J.A.; Rostler, P.S.
1995-04-25
A system for non-destructively measuring an object and controlling industrial processes in response to the measurement is disclosed in which an impulse laser generates a plurality of sound waves over timed increments in an object. A polarizing interferometer is used to measure surface movement of the object caused by the sound waves and sensed by phase shifts in the signal beam. A photon multiplier senses the phase shift and develops an electrical signal. A signal conditioning arrangement modifies the electrical signals to generate an average signal correlated to the sound waves which in turn is correlated to a physical or metallurgical property of the object, such as temperature, which property may then be used to control the process. External, random vibrations of the workpiece are utilized to develop discernible signals which can be sensed in the interferometer by only one photon multiplier. In addition the interferometer includes an arrangement for optimizing its sensitivity so that movement attributed to various waves can be detected in opaque objects. The interferometer also includes a mechanism for sensing objects with rough surfaces which produce speckle light patterns. Finally the interferometer per se, with the addition of a second photon multiplier is capable of accurately recording beam length distance differences with only one reading. 38 figs.
International Nuclear Information System (INIS)
Kussmann, Jörg; Luenser, Arne; Beer, Matthias; Ochsenfeld, Christian
2015-01-01
An analytical method to calculate the molecular vibrational Hessian matrix at the self-consistent field level is presented. By analysis of the multipole expansions of the relevant derivatives of Coulomb-type two-electron integral contractions, we show that the effect of the perturbation on the electronic structure due to the displacement of nuclei decays at least as r −2 instead of r −1 . The perturbation is asymptotically local, and the computation of the Hessian matrix can, in principle, be performed with O(N) complexity. Our implementation exhibits linear scaling in all time-determining steps, with some rapid but quadratic-complexity steps remaining. Sample calculations illustrate linear or near-linear scaling in the construction of the complete nuclear Hessian matrix for sparse systems. For more demanding systems, scaling is still considerably sub-quadratic to quadratic, depending on the density of the underlying electronic structure
Nurok, Michael; Lipsitz, Stuart; Satwicz, Paul; Kelly, Andrea; Frankel, Allan
2010-05-01
To create and test a reproducible method for measuring emotional climate, surgical team skills, and threats to patient outcome by conducting an observational study to assess the impact of a surgical team skills and communication improvement intervention on these measurements. Observational study. Operating rooms in a high-volume thoracic surgery center from September 5, 2007, through June 30, 2008. Thoracic surgery operating room teams. Two 90-minute team skills training sessions focused on findings from a standardized safety culture survey administered to all participants and highlighting positive and problematic aspects of team skills, communication, and leadership. The sessions created an interactive forum to educate team members on the importance of communication and to role-play optimal interactive and communication strategies. Calculated indices of emotional climate, team skills, and threat to patient outcome. The calculated communication and team skills score improved from the preintervention to postintervention periods, but the improvement extinguished during the 3 months after the intervention (P skills and communication and decrease a calculated score of threats to patient outcome. However, the effect is only durable for threats to patient outcome.
Reproducibility of isotope ratio measurements
International Nuclear Information System (INIS)
Elmore, D.
1981-01-01
The use of an accelerator as part of a mass spectrometer has improved the sensitivity for measuring low levels of long-lived radionuclides by several orders of magnitude. However, the complexity of a large tandem accelerator and beam transport system has made it difficult to match the precision of low energy mass spectrometry. Although uncertainties for accelerator measured isotope ratios as low as 1% have been obtained under favorable conditions, most errors quoted in the literature for natural samples are in the 5 to 20% range. These errors are dominated by statistics and generally the reproducibility is unknown since the samples are only measured once
Evaluation of multichannel reproduced sound
DEFF Research Database (Denmark)
Choisel, Sylvain; Wickelmaier, Florian Maria
2007-01-01
A study was conducted with the goal of quantifying auditory attributes which underlie listener preference for multichannel reproduced sound. Short musical excerpts were presented in mono, stereo and several multichannel formats to a panel of forty selected listeners. Scaling of auditory attributes......, as well as overall preference, was based on consistency tests of binary paired-comparison judgments and on modeling the choice frequencies using probabilistic choice models. As a result, the preferences of non-expert listeners could be measured reliably at a ratio scale level. Principal components derived...
International Nuclear Information System (INIS)
Paniagua, L.; Munoz, M.; Moreno, F.; Arroyo, J.; Monne, C.
2014-01-01
Maintenance Technicians, more and more, must dispose of predictive tools to diagnose the state of the equipment, especially if they are responsible for the emergency diesel in a Nuclear Power Plant. the use of these tools should be understood as a complement to more classic Preventive Maintenance of the equipment, thus increasing their availability because the parameters necessary for evaluating motor behaviour are taken while the engine is in operation. In this way, it facilitates the decision-making on whether to carry out certain preventive tasks. The basic information about this diagnostic tool presented in this article is based on the reading, recording and analysis of pressure, vibrations and acoustic emission in each engine cylinder during its operating cycle. A nice addition to the above diagnosis is carrying out and endoscopy of each cylinder, which enables the observation of: water leaks, injector leaks, the spraying of each injector, valve leaks,... etc. This article describes the fundamentals of a non-intrusive, easy to use and low cost tool, used to check the function of Emergency Diesel engines, as well as the experience of its use in the St. Maria Garona Nuclear Plant. The article also describes the case of a fault which occurred in the Nuclear Power plant in Garona that would hardly have been possible to detect by other means. This tool was developed jointly by the Engines Laboratory of the Department of Mechanical Engineering at the University of Zaragoza and the St. Maria Garona Nuclear Plant. It has been further improved, extended and optimized over the more than 10 years of its use. (Author)
Evaluation of vibration and vibration fatigue life for small bore pipe in nuclear power plants
International Nuclear Information System (INIS)
Wang Zhaoxi; Xue Fei; Gong Mingxiang; Ti Wenxin; Lin Lei; Liu Peng
2011-01-01
The assessment method of the steady state vibration and vibration fatigue life of the small bore pipe in the supporting system of the nuclear power plants is proposed according to the ASME-OM3 and EDF evaluation methods. The GGR supporting pipe system vibration is evaluated with this method. The evaluation process includes the filtration of inborn sensitivity, visual inspection, vibration tests, allowable vibration effective velocity calculation and vibration stress calculation. With the allowable vibration effective velocity calculated and the vibration velocity calculated according to the acceleration data tested, the filtrations are performed. The vibration stress at the welding coat is calculated with the spectrum method and compared with the allowable value. The response of the stress is calculated with the transient dynamic method, with which the fatigue life is evaluated with the Miners linear accumulation model. The vibration stress calculated with the spectrum method exceeds the allowable value, while the fatigue life calculated from the transient dynamic method is larger than the designed life with a big safety margin. (authors)
Aircraft gas turbine engine vibration diagnostics
Directory of Open Access Journals (Sweden)
Stanislav Fábry
2017-11-01
Full Text Available In the Czech and Slovak aviation are in service elderly aircrafts, usually produced in former Soviet Union. Their power units can be operated in more efficient way, in case of using additional diagnostic methods that allow evaluating their health. Vibration diagnostics is one of the methods indicating changes of rotational machine dynamics. Ground tests of aircraft gas turbine engines allow vibration recording and analysis. Results contribute to airworthiness evaluation and making corrections, if needed. Vibration sensors distribution, signal recording and processing are introduced in a paper. Recorded and re-calculated vibration parameters are used in role of health indicators.
International Nuclear Information System (INIS)
Fritzen, M.R.; Fritzen, T.A.
1994-01-01
Anytime that blasting operations will be conducted near existing inhabited structures, vibration damage claims are a major concern of the blasting contractor. It has been the authors' experience that even when vibration and airblast levels generated from a blast are well below accepted damage thresholds, damage claims can still arise. The single greatest source of damage claims is the element of surprise associated with not knowing that blasting operations are being conducted nearby. The second greatest source of damage claims arise form the inability to produce accurate and detailed records of all blasting activity which provides evidence that vibration and air blast levels from each blast had been taken by seismic recording equipment. Using a two part plan consisting of extensive public relations followed by a detailed and accurate monitoring and recording of blasting operations has resulted in no substantiated claims of damage since its' incorporation. The authors experience shows that by using this two part process when conducting blasting operations near inhabited structures, unsubstantiated blast vibration damage claims may be significantly reduced
Energy Technology Data Exchange (ETDEWEB)
Fritzen, M.R.; Fritzen, T.A. [Blasting Technology, Inc., Maui, HI (United States)
1994-12-31
Anytime that blasting operations will be conducted near existing inhabited structures, vibration damage claims are a major concern of the blasting contractor. It has been the authors` experience that even when vibration and airblast levels generated from a blast are well below accepted damage thresholds, damage claims can still arise. The single greatest source of damage claims is the element of surprise associated with not knowing that blasting operations are being conducted nearby. The second greatest source of damage claims arise form the inability to produce accurate and detailed records of all blasting activity which provides evidence that vibration and air blast levels from each blast had been taken by seismic recording equipment. Using a two part plan consisting of extensive public relations followed by a detailed and accurate monitoring and recording of blasting operations has resulted in no substantiated claims of damage since its` incorporation. The authors experience shows that by using this two part process when conducting blasting operations near inhabited structures, unsubstantiated blast vibration damage claims may be significantly reduced.
Kalanoor, Basanth S; Ronen, Maria; Oren, Ziv; Gerber, Doron; Tischler, Yaakov R
2017-03-31
The low-frequency vibrational (LFV) modes of biomolecules reflect specific intramolecular and intermolecular thermally induced fluctuations that are driven by external perturbations, such as ligand binding, protein interaction, electron transfer, and enzymatic activity. Large efforts have been invested over the years to develop methods to access the LFV modes due to their importance in the studies of the mechanisms and biological functions of biomolecules. Here, we present a method to measure the LFV modes of biomolecules based on Raman spectroscopy that combines volume holographic filters with a single-stage spectrometer, to obtain high signal-to-noise-ratio spectra in short acquisition times. We show that this method enables LFV mode characterization of biomolecules even in a hydrated environment. The measured spectra exhibit distinct features originating from intra- and/or intermolecular collective motion and lattice modes. The observed modes are highly sensitive to the overall structure, size, long-range order, and configuration of the molecules, as well as to their environment. Thus, the LFV Raman spectrum acts as a fingerprint of the molecular structure and conformational state of a biomolecule. The comprehensive method we present here is widely applicable, thus enabling high-throughput study of LFV modes of biomolecules.
International Nuclear Information System (INIS)
Namita, Yoshio; Kawahata, Jun-ichi; Ichihashi, Ichiro; Fukuda, Toshihiko.
1995-01-01
Component and piping systems in current nuclear power plants and chemical plants are designed to employ many supports to maintain safety and reliability against earthquakes. However, these supports are rigid and have a slight energy-dissipating effect. It is well known that applying high-damping supports to the piping system is very effective for reducing the seismic response. In this study, we investigated the design method of the elastoplastic damper [energy absorber (EAB)] and the seismic design method for a piping system supported by the EAB. Our final goal is to develop technology for applying the EAB to the piping system of an actual plant. In this paper, the vibration test results of the three-dimensional piping model are presented. From the test results, it is confirmed that EAB has a large energy-dissipating effect and is effective in reducing the seismic response of the piping system, and that the seismic design method for the piping system, which is the response spectrum mode superposition method using each modal damping and requires iterative calculation of EAB displacement, is applicable for the three-dimensional piping model. (author)
Chanbi, Daoud; Ogam, Erick; Amara, Sif Eddine; Fellah, Z E A
2018-05-07
Precise but simple experimental and inverse methods allowing the recovery of mechanical material parameters are necessary for the exploration of materials with novel crystallographic structures and elastic properties, particularly for new materials and those existing only in theory. The alloys studied herein are of new atomic compositions. This paper reports an experimental study involving the synthesis and development of methods for the determination of the elastic properties of binary (Fe-Al, Fe-Ti and Ti-Al) and ternary (Fe-Ti-Al) intermetallic alloys with different concentrations of their individual constituents. The alloys studied were synthesized from high purity metals using an arc furnace with argon flow to ensure their uniformity and homogeneity. Precise but simple methods for the recovery of the elastic constants of the isotropic metals from resonant ultrasound vibration data were developed. These methods allowed the fine analysis of the relationships between the atomic concentration of a given constituent and the Young’s modulus or alloy density.
Theory And Working Of Noise And Vibration
International Nuclear Information System (INIS)
Jeong, Il Rok
1988-09-01
This book deals with theory of noise including physical property of noise like term and characteristic of sound, occurrence of sound, characteristic of noise pollution and main cause of occurrence of noise, technique of prevention of noise with noise reduction, construction guide for prevention of noise, and measure of interior noise. It also has the theory of vibration such as an introduction of vibration, and technology of prevention of vibration, official test method of environmental pollution, and summary of protection of the environment.
Enhanced vibration diagnostics using vibration signature analysis
International Nuclear Information System (INIS)
Ahmed, S.; Shehzad, K.; Zahoor, Y.; Mahmood, A.; Bibi, A.
2001-01-01
Symptoms will appear in equipment, as well as in human beings. when 'suffering from sickness. Symptoms of abnormality in equipment are vibration, noise, deformation, temperature, pressure, electric current, crack, wearing, leakage etc. these are called modes of failure. If the mode of failure is vibration then the vibration signature analysis can be effectively used in order to diagnose the machinery problems. Much valuable information is contained within these vibration 'Spectra' or 'Signatures' but is only of use if the analyst can unlock its 'Secrets'. This paper documents a vibration problem in the motor of a centrifugal pump (Type ETA). It focuses mainly on the roll of modern vibration monitoring system in problem analysis. The problem experienced was the motor unstability and noise due to high vibration. Using enhanced vibration signature data, the problem was analyzed. which suggested that the rotor eccentricity was the cause of excessive noise and vibration in the motor. In conclusion, advanced electronic monitoring and diagnostic systems provide powerful information for machine's condition assessment and problem analysis. Appropriate interpretation and use of this information is important for accurate and effective vibration analysis. (author)
de Beer, Alex G F; Samson, Jean-Sebastièn; Hua, Wei; Huang, Zishuai; Chen, Xiangke; Allen, Heather C; Roke, Sylvie
2011-12-14
We present a direct comparison of phase sensitive sum-frequency generation experiments with phase reconstruction obtained by the maximum entropy method. We show that both methods lead to the same complex spectrum. Furthermore, we discuss the strengths and weaknesses of each of these methods, analyzing possible sources of experimental and analytical errors. A simulation program for maximum entropy phase reconstruction is available at: http://lbp.epfl.ch/. © 2011 American Institute of Physics
Active vibration isolation of a rigidly mounted turbo pump
Basten, T.G.H.; Doppenberg, E.J.J.
2006-01-01
Manufacturers of precision equipment are constantly aiming at increased accuracy. Elimination of disturbing vibrations is therefore getting more and more important. The technical limitations of passive isolation methods require alternative strategies for vibration reduction, such as active
Systematic vibration thermodynamic properties of bromine
Liu, G. Y.; Sun, W. G.; Liao, B. T.
2015-11-01
Based on the analysis of the maturity and finiteness of vibrational levels of bromine molecule in ground state and evaluating the effect on statistical computation, according to the elementary principles of quantum statistical theorem, using the full set of bromine molecular vibrational levels determined with algebra method, the statistical contribution for bromine systematical macroscopic thermodynamic properties is discussed. Thermodynamic state functions Helmholtz free energy, entropy and observable vibration heat capacity are calculated. The results show that the determination of full set of vibrational levels and maximum vibrational quantum number is the key in the correct statistical analysis of bromine systematical thermodynamic property. Algebra method results are clearly different from data of simple harmonic oscillator and the related algebra method results are no longer analytical but numerical and are superior to simple harmonic oscillator results. Compared with simple harmonic oscillator's heat capacities, the algebra method's heat capacities are more consistent with the experimental data in the given temperature range of 600-2100 K.
[Occupational standing vibration rate and vibrational diseases].
Karnaukh, N G; Vyshchipan, V F; Haumenko, B S
2003-12-01
Occupational standing vibration rate is proposed in evaluating a degree of impairment of an organism activity. It will allow more widely to introduce specification of quality and quantity in assessment of the development of vibrational disease. According out-patient and inpatient obtained data we have established criterial values of functional changes in accordance with accumulated occupational standing vibration rate. The nomogram was worked out for defining a risk of the development of vibrational disease in mine workers. This nomogram more objectively can help in diagnostics of the disease.
Directory of Open Access Journals (Sweden)
Angélica Lemos Debs Diniz
2009-12-01
Full Text Available OBJETIVO: O objetivo deste estudo é avaliar a variabilidade interobservador do método ultrassonográfico para medida da gordura subcutânea, visceral e perirrenal por meio de técnica padronizada. MATERIAIS E MÉTODOS: Foram avaliados 50 pacientes entre novembro de 2006 e janeiro de 2007. A medida da espessura subcutânea foi realizada com transdutor linear de 7,5 MHz posicionado transversalmente a 1 cm acima da cicatriz umbilical. Para a gordura visceral foi utilizado transdutor de 3,5 MHz posicionado 1 cm acima da cicatriz umbilical, considerando-se a medida entre a face interna do músculo reto abdominal e a parede posterior da aorta na linha média do abdome. A gordura perirrenal foi medida no terço médio do rim direito, com transdutor posicionado na linha axilar média. RESULTADOS: A reprodutibilidade interobservador foi analisada por meio do teste t de Student, com significância de 95%. Não houve diferença significativa entre as médias das medidas das gorduras subcutânea, visceral e perirrenal, com p = 0,7141, 0,7286 e 0,6368, respectivamente. As médias encontradas, com seus respectivos desvios-padrão, foram: 2,64 ± 1,37 para a espessura subcutânea, 6,84 ± 2,38 para a espessura visceral e 4,89 ± 2,6 para a espessura perirrenal. CONCLUSÃO: A ultrassonografia apresentou boa reprodutibilidade interobservador para avaliação da gordura abdominal por meio das medidas das espessuras subcutânea, visceral e perirrenal.OBJECTIVE: The purpose of this study was to evaluate the interobserver variability of ultrasound in the measurement of subcutaneous, visceral and perirenal fat through standard technique. MATERIALS AND METHODS: From November 2006 to January 2007, 50 patients were evaluated. The subcutaneous fat thickness was measured with a 7.5 MHz linear transducer transversely positioned 1 cm above the umbilical scar. For the visceral fat, a 3.5 MHz transducer was also positioned 1 cm above the umbilical scar, considering the
Nepomuceno, Miguel C. S.; Lopes, Sérgio M. R.
2017-10-01
Non-destructive tests (NDT) have been used in the last decades for the assessment of in-situ quality and integrity of concrete elements. An important step in the application of NDT methods concerns to the interpretation and validation of the test results. In general, interpretation of NDT results should involve three distinct phases leading to the development of conclusions: processing of collected data, analysis of within-test variability and quantitative evaluation of property under investigation. The analysis of within-test variability can provide valuable information, since this can be compared with that of within-test variability associated with the NDT method in use, either to provide a measure of the quality control or to detect the presence of abnormal circumstances during the in-situ application. This paper reports the analysis of the experimental results of within-test variability of NDT obtained for normal vibrated concrete and self-compacting concrete. The NDT reported includes the surface hardness test, ultrasonic pulse velocity test, penetration resistance test, pull-off test, pull-out test and maturity test. The obtained results are discussed and conclusions are presented.
Energy Technology Data Exchange (ETDEWEB)
Sadaoka, N.; Umegaki, K. [Hitachi, Ltd., Tokyo (Japan)
1996-01-25
A vortex-induced vibration of an array of elastically supported tubes is simulated in two-dimension by using a flow-induced vibration analysis program, which was developed in order to evaluate flow-induced vibration in various components such as heat exchangers. From a comparison of calculated results and experimental data, the following points are observed. (1) For the calculated results in a 5 {times} 5 square array, the flow pattern surrounding the first-row tubes is markedly different from that observed in the second-row or third-row tubes. This flow pattern is the same as that obtained from the experiment. (2) All tubes begin to oscillate due to unsteady fluid force and the oscillating mode is different for each row of tubes. These oscillation patterns show the same tendency in the experiments and it is concluded that the developed method can simulate vortex-induced vibration in an array of elastically supported tubes. 19 refs., 10 figs., 1 tab.
Reproducible research: a minority opinion
Drummond, Chris
2018-01-01
Reproducible research, a growing movement within many scientific fields, including machine learning, would require the code, used to generate the experimental results, be published along with any paper. Probably the most compelling argument for this is that it is simply following good scientific practice, established over the years by the greats of science. The implication is that failure to follow such a practice is unscientific, not a label any machine learning researchers would like to carry. It is further claimed that misconduct is causing a growing crisis of confidence in science. That, without this practice being enforced, science would inevitably fall into disrepute. This viewpoint is becoming ubiquitous but here I offer a differing opinion. I argue that far from being central to science, what is being promulgated is a narrow interpretation of how science works. I contend that the consequences are somewhat overstated. I would also contend that the effort necessary to meet the movement's aims, and the general attitude it engenders would not serve well any of the research disciplines, including our own.