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1

Effects of Vibration Stress and Temperature on the Characteristics of Piezoelectric Ceramics under High Vibration Amplitude Levels Measured by Electrical Transient Responses  

Microsoft Academic Search

This paper presents a characteristic evaluation of piezoelectric ceramics at high vibration amplitude levels of resonance, based on the electrical transient response technique. Low-Q and high-Q materials are measured, and the effect of vibration stress is obtained without affecting temperature. It is revealed that for low-Q materials an increase of loss is caused mainly by the vibration stress, while for

Mikio Umeda; Kentaro Nakamura; Sadayuki Ueha

1999-01-01

2

Impedance response characteristics of the primate Mucaca mulatta exposed to seated whole-body gz vibration.  

PubMed

A mathematical model was used to quantify and describe the variability in the mechanical impedance response of the Rhesus monkey subjected to vibrations in the range 3-20 Hz at 0.5 g peak acceleration. Due to the similarities in response, a two-mass, one-degree-of-freedom (DOF) model was selected and the associated mechanical parameters determined using a nonlinear least-squares optimization program. For the six tests conducted on each of the four subjects, appreciable parameter variations were observed within a subject; however, the majority of the mean parameter values among different subjects and among the repeated tests on the population were within +/- 1 S.D. of each other. Significant differences were observed in the stiffness coefficient and the total mass among different subjects, and in the mass ratio (between inert and sprung masses) among the repeated tests. Variations in the profile shapes following resonance were described and limited by changes in the mass ratio and the damping factor. Higher mass ratios (greater than 1.0) were associated with lower damping factors (less than 0.50). The impedance response beyond resonance approached the response described by the impedance of the inert mass and the damper elements of the model combined in parallel, and supported the assumption that the lower torso was rigidly attached to the seat. Physically, the reactive force produced by the upper torso increasingly diminished following resonance, due to the load transmission/attenuation characteristics of the spinal structures at 0.5 g peak acceleration. The impedance measured at the seat becomes dominated by the transmitted damping force associated with the spine and the force generated by the rigid lower-torso mass. PMID:1639828

Smith, S D

1992-08-01

3

Vibration, performance, flutter and forced response characteristics of a large-scale propfan and its aeroelastic model  

NASA Technical Reports Server (NTRS)

An investigation of the vibration, performance, flutter, and forced response of the large-scale propfan, SR7L, and its aeroelastic model, SR7A, has been performed by applying available structural and aeroelastic analytical codes and then correlating measured and calculated results. Finite element models of the blades were used to obtain modal frequencies, displacements, stresses and strains. These values were then used in conjunction with a 3-D, unsteady, lifting surface aerodynamic theory for the subsequent aeroelastic analyses of the blades. The agreement between measured and calculated frequencies and mode shapes for both models is very good. Calculated power coefficients correlate well with those measured for low advance ratios. Flutter results show that both propfans are stable at their respective design points. There is also good agreement between calculated and measured blade vibratory strains due to excitation resulting from yawed flow for the SR7A propfan. The similarity of structural and aeroelastic results show that the SR7A propfan simulates the SR7L characteristics.

August, Richard; Kaza, Krishna Rao V.

1988-01-01

4

Impact-absorbing characteristics by applying ultrasonic vibration  

NASA Astrophysics Data System (ADS)

An impact-absorbing device that facilitates the application of ultrasonic vibrations was devised. Vibration distributions, springback characteristics, and impact-absorption characteristics were measured. We confirm that the springback amount decreases and the impact is absorbed upon the application of ultrasonic vibrations. When an aluminum alloy plate is crumpled, the maximum output voltage of the attached shock sensor decreases to 65% upon the application of ultrasonic vibrations as compared to when the ultrasonic vibrations are not applied.

Suzuki, Atsuyuki; Ueki, Eiichiro; Tsujino, Jiromaru

2012-05-01

5

Effect of Vibration on Retention Characteristics of Screen Acquisition Systems  

NASA Technical Reports Server (NTRS)

An analytical and experimental investigation of the effect of vibration on the retention characteristics of screen acquisition systems was performed. The functioning of surface tension devices using fine-mesh screens requires that the pressure differential acting on the screen be less than its pressure retention capability. When exceeded, screen breakdown will occur and gas-free expulsion of propellant will no longer be possible. An analytical approach to predicting the effect of vibration was developed. This approach considers the transmission of the vibration to the screens of the device and the coupling of the liquid and the screen in establishing the screen response. A method of evaluating the transient response of the gas/liquid interface within the screen was also developed.

Tegart, J. R.; Park, A. C.

1977-01-01

6

Human response to vibration in residential environments.  

PubMed

This paper presents the main findings of a field survey conducted in the United Kingdom into the human response to vibration in residential environments. The main aim of this study was to derive exposure-response relationships for annoyance due to vibration from environmental sources. The sources of vibration considered in this paper are railway and construction activity. Annoyance data were collected using questionnaires conducted face-to-face with residents in their own homes. Questionnaires were completed with residents exposed to railway induced vibration (N?=?931) and vibration from the construction of a light rail system (N?=?350). Measurements of vibration were conducted at internal and external positions from which estimates of 24-h vibration exposure were derived for 1073 of the case studies. Sixty different vibration exposure descriptors along with 6 different frequency weightings were assessed as potential predictors of annoyance. Of the exposure descriptors considered, none were found to be a better predictor of annoyance than any other. However, use of relevant frequency weightings was found to improve correlation between vibration exposure and annoyance. A unified exposure-response relationship could not be derived due to differences in response to the two sources so separate relationships are presented for each source. PMID:24437758

Waddington, David C; Woodcock, James; Peris, Eulalia; Condie, Jenna; Sica, Gennaro; Moorhouse, Andrew T; Steele, Andy

2014-01-01

7

Vibrational and acoustic response of ribbed plates  

NASA Astrophysics Data System (ADS)

A self-consistent mathematical formulation, using the Fourier transform method and a direct Gaussian numerical integration scheme, is developed and verified for analysis of both vibrational and acoustic responses of infinite submerged ribbed plates. Further steps developed from standard theories make structural intensity, acoustic intensity, and acoustic power calculations possible in the nearfield and farfield and are demonstrated in this work. The direct numerical integration scheme adopted to obtain responses has proved to be straightforward and reliable. Although the double integration expression in some responses makes the technique infeasible, a practical way to overcome that difficulty is demonstrated using a standard branch-cut integration to eliminate one integration step analytically. The model and numerical scheme readily allow investigation of additional interesting topics, like the passband and stopband characteristic and the mode localization phenomenon that are observed in ribbed structures. Furthermore, an extension to comprehension of the mechanisms that generate the mode localization phenomenon on disordered structures has been realized. A secondary effort examines natural modes of vibration and acoustic radiation for finite stiffened multiple-span beams with the efficient transfer matrix method. This model shows that the mode localization phenomenon exists on disordered stiffened beams both under free-free and hinged-hinged end conditions. The sensitivity of the response to attachment disorder (perturbations in rib stiffness and location) has also been examined. An elaborate vibrational and acoustic experiment has been carried out on a baffled, stiffened, two-span, hinged beam to examine the existence of the localized modes and verify the predicted acoustic responses. Moreover, the radiation efficiency of finite beams has been investigated for comparison of the radiation behavior presented by the different stiffened beam arrangements. A thorough investigation of mode localization, frequency passbands and stopbands, structural and acoustic intensities, and radiated acoustic power is presented for analysis of submerged infinite ribbed plates with variable rib materials geometry and spacing (periodic and nonperiodic). A second investigation of localized natural modes is demonstrated for analysis and experiment of finite stiffened beams in air.

Juang, Ten-Bin

1993-01-01

8

Physiology responses of Rhesus monkeys to vibration  

NASA Astrophysics Data System (ADS)

Vibration is one of the important environmental factors in space vehicles that it can induce severe physiological responses in most of the body systems such as cardiovascular, respiratory, skeletal, endocrine, and etc. This investigation was to assess the effect of different vibration frequencies on heart rate variability (HRV), electrocardiograms (ECG) and respiratory rate in Rhesus monkeys. Methods: two groups of rhesus monkey (n=16 in each group) was selected as control and intervention groups. Monkeys were held in a sitting position within a specific fixture. The animals of this experiment were vibrated on a table which oscillated right and left with sinusoidal motion. Frequency and acceleration for intervention group were between the range of 1 to 2000 Hz and +0.5 to +3 G during 36 weeks (one per week for 15 min), respectively. All of the animals passed the clinical evaluation (echocardiography, sonography, radiography and blood analysis test) before vibration test and were considered healthy and these tests repeated during and at the end of experiments. Results and discussions: Our results showed that heart and respiratory rates increased significantly in response to increased frequency from 1 to 60 Hz (p <0.05) directly with the +G level reaching a maximum (3G) within a seconds compare to controls. There were no significant differences in heart and respiratory rate from 60 t0 2000 Hz among studied groups. All monkeys passed vibration experiment successfully without any arrhythmic symptoms due to electrocardiography analysis. Conclusion: Our results indicate that vibration in low frequency can effect respiratory and cardiovascular function in rhesus monkey. Keywords: Vibration, rhesus monkey, heart rate, respiratory rate

Hajebrahimi, Zahra; Ebrahimi, Mohammad; Alidoust, Leila; Arabian Hosseinabadi, Maedeh

9

Welding Characteristics of Ultrasonic Seam Welding System Using a Complex Vibration Circular Disk Welding Tip  

Microsoft Academic Search

The continuous welding characteristics of a 27 kHz ultrasonic seam welding system using a complex vibration circular disk welding tip are studied. The vibration characteristics of a complex vibration converter were improved compared with the prototype model. The circular disk welding tip vibrates in both transverse and torsional vibration modes and an elliptical vibration locus is obtained at the circumference

Jiromaru Tsujino; Tetsugi Ueoka

2000-01-01

10

System identification of suspension bridge from ambient vibration response  

Microsoft Academic Search

The paper addresses and evaluates the application of system identification to a suspension bridge using ambient vibration response. To obtain dynamic characteristics of the bridge, two output-only time-domain system identification methods are employed namely, the Random Decrement Method combined with the Ibrahim Time Domain (ITD) method and the Natural Excitation Technique (NExT) combined with the Eigensystem Realization Algorithm (ERA). Accuracy

Dionysius M. Siringoringo; Yozo Fujino

2008-01-01

11

Effects of vibration characteristics on the walking discomfort of floating floors on concrete slabs.  

PubMed

In the present study, the vibration characteristics of floating floor systems and the discomfort in walking upon them have been studied in concrete slab structures through mock-up floors experiments. Seven types of floor systems, with panels of various sizes and supporting beams with different joist spacings, were constructed based on actual conditions. For the vibration measurement, an ISO rubber ball dropped from a height of 20?cm was used as an impact source to reproduce human walking. The vibration characteristics were evaluated by calculating the vibration acceleration values and the autocorrelation function parameters for the floor structures. Finally, a human walking experiment was conducted to investigate subjective responses to the vibration characteristics of floating floors. From the results, it was found that the vibration acceleration values and walking discomfort varied with the supporting conditions of the floors and that these were highly correlated with each other. It was also found that more than 75% of subjects accepted the floors when the vibration value of the floor in terms of vibration does value (VDV) is below 4.8?ms(-1.75). In addition, a practical regression of the VDV was obtained and design guidelines for floating floors were suggested. PMID:25324073

Kim, Jae Ho; Jeon, Jin Yong

2014-10-01

12

Dynamic characteristics of a vibrating beam with periodic variation in bending stiffness  

NASA Technical Reports Server (NTRS)

A detailed dynamic analysis is performed of a vibrating beam with bending stiffness periodic in the spatial coordinate. Using a perturbation expansion technique the free vibration solution is obtained in a closed-form, and the effects of system parameters on beam response are explored. It is found that periodic stiffness acts to modulate the modal displacements from the characteristic shape of a simple sine wave. The results are verified by a finite element solution and through experimental testing.

Townsend, John S.

1987-01-01

13

Vertical Vibration Characteristics of a High-Temperature Superconducting Maglev Vehicle System  

NASA Astrophysics Data System (ADS)

The vertical vibration characteristics of a high-temperature superconducting maglev vehicle system are investigated experimentally. The displacement variations of the maglev vehicle system are measured with different external excitation frequency, in the case of a certain levitation gap. When the external vibration frequency is low, the amplitude variations of the response curve are small. With the increase of the vibration frequency, chaos status can be found. The resonance frequencies with difference levitation gap are also investigated, while the external excitation frequency range is 0-100 Hz. Along with the different levitation gap, resonance frequency is also different. There almost is a linear relationship between the levitation gap and the resonance frequency.

Jiang, Jing; Li, Ke Cai; Zhao, Li Feng; Ma, Jia Qing; Zhang, Yong; Zhao, Yong

2013-06-01

14

Vibration characteristics of a steadily rotating slender ring  

NASA Technical Reports Server (NTRS)

Partial differential equations are derived to describe the structural vibrations of a uniform homogeneous ring which is very flexible because the radius is very large compared with the cross sectional dimensions. Elementary beam theory is used and small deflections are assumed in the derivation. Four sets of structural modes are examined: bending and compression modes in the plane of the ring; bending modes perpendicular to the plane of the ring; and twisting modes about the centroid of the ring cross section. Spatial and temporal characteristics of these modes, presented in terms of vibration frequencies and ratios between vibration amplitudes, are demonstrated in several figures. Given a sufficiently high rotational rate, the dynamics of the ring approach those of a vibrating string. In this case, the velocity of traveling wave in the material of the ring approaches in velocity of the material relative to inertial space, resulting in structural modes which are almost stationary in space.

Lallman, F. J.

1980-01-01

15

A direct evidence of vibrationally delocalized response at ice surface.  

PubMed

Surface-specific vibrational spectroscopic responses at isotope diluted ice and amorphous ice are investigated by molecular dynamics (MD) simulations combined with quantum mechanics/molecular mechanics calculations. The intense response specific to the ordinary crystal ice surface is predicted to be significantly suppressed in the isotopically diluted and amorphous ices, demonstrating the vibrational delocalization at the ordinary ice surface. The collective vibration at the ice surface is also analyzed with varying temperature by the MD simulation. PMID:25399168

Ishiyama, Tatsuya; Morita, Akihiro

2014-11-14

16

A direct evidence of vibrationally delocalized response at ice surface  

NASA Astrophysics Data System (ADS)

Surface-specific vibrational spectroscopic responses at isotope diluted ice and amorphous ice are investigated by molecular dynamics (MD) simulations combined with quantum mechanics/molecular mechanics calculations. The intense response specific to the ordinary crystal ice surface is predicted to be significantly suppressed in the isotopically diluted and amorphous ices, demonstrating the vibrational delocalization at the ordinary ice surface. The collective vibration at the ice surface is also analyzed with varying temperature by the MD simulation.

Ishiyama, Tatsuya; Morita, Akihiro

2014-11-01

17

Vibrational characteristics of Balinese gamelan metallophones.  

PubMed

A study of the eight metallophone pairs from a Balinese gamelan semara dana has been conducted. Acoustical recordings of metallophone bars being struck were used to examine ratios of overtone frequencies to the fundamental. Results showed large variability in the number and ratios of overtones present. Scanning laser Doppler vibrometry measurements made on several bars also revealed great variability in mode shapes present. The distribution of prominent overtones and their modal shapes do not appear to match those of Western metallophones. Notably, the overall gamelan metallophone characteristics are quite dissimilar to the glockenspiel, which disagrees with previous studies. PMID:21117714

Jones, Molly E; Gee, Kent L; Grimshaw, Jeremy

2010-05-01

18

Vibration characteristics of aluminum material and its influences on laser Doppler voice acquisition  

NASA Astrophysics Data System (ADS)

Laser Doppler technology is widely used in precision vibration measurement such as voice acquisition. The fundamental of voice acquisition is to detect the vibration of targets induced by sound wave using a Laser Doppler voice acquisition system, and then demodulate the voice signal from interference signal. Therefore the target's vibration characteristics will be the principal factor influencing the effect of voice acquisition. In this paper, we focus on the plane structure's vibration characteristics caused by voice. There are mainly two parts in this paper, simulation and experimental verify. In simulation, the finite element method is used. The Finite Element Analysis method is widely used in material properties analysis, dynamic analysis, and acoustic analysis. Through finite element analysis method, the plane structure models of thick smooth aluminum are established by ANSYS. Then the frequency responses of different constraints are compared. The Laser Doppler voice acquisition system is applied to test and verify the simulation results. The response characteristics of aluminum board under different excitation frequency are measured. The experimental results and simulation results are compared to verify the correctness and reasonableness of simulation. At the same time, this provides theoretical guidance for Laser Doppler voice acquisition system to choose targets and improve voice acquisition performance.

Zhang, Yu-ze; Li, Li-yan; Tong, You-wan; Zeng, Hua-lin; Zhou, Yan

2013-09-01

19

Aircraft noise induced building vibration and effects on human response  

NASA Technical Reports Server (NTRS)

The acoustic loads resulting from aircraft noise and sonic booms which can induce vibration in the structure and result in radiation of noise into its interior, rattling of items in contact with the structure, and the perception of the inhabitants that the structure is vibrating, are investigated. In particular, the response of buildings, particularly residential structures, to aircraft noise and the resulting effects on human response have been the subjects of considerable research at the NASA Langley Research Center. These studies are reviewed with particular emphasis on the response of houses to aircraft overflight noise and any increase in noise annoyance caused by the perception of vibration and rattling.

Powell, Clemans A.; Shepherd, Kevin P.

1989-01-01

20

Evaluation of High Freuqency Vibrator Response  

E-print Network

Accurate analysis of the motion of a commercial high frequency hydraulic vibrator commonly used for near-surface applications demonstrated that the rigid body assumption of the weighted-sum approximation is not valid ...

Hendrix, Craig Michael

2012-08-12

21

Dynamic characteristics of a vibrating beam with periodic variation in bending stiffness  

NASA Technical Reports Server (NTRS)

A detailed dynamic analysis is performed of a vibrating beam with bending stiffness periodic in the spatial coordinate. The effects of system parameters on beam response are explored with a perturbation expansion technique. It is found that periodic stiffness acts to modulate the modal displacements from the characteristic shape of a simple sine wave. The results are verified by a finite element solution and through experimental testing.

Townsend, John S.

1987-01-01

22

The flaminio obelisk in Rome: vibrational characteristics as part of preservation efforts  

USGS Publications Warehouse

The purpose of the paper is to study the vibrational characteristics of the Flaminio Obelisk in Rome as part of general studies being performed for preservation purposes. The state of preservation of the monument is described as well as the sonic method used to evaluate the integrity of the sections. The results of the sonic tests are used to determine reductions in the cross-sectional properties. A stick model including two rotational frequency independent soil springs at the basement level of the obelisk is developed. A response spectrum and stress analysis according to the Italian Seismic Code is performed considering and evaluating the degraded characteristics of sections. -from Authors

Bongiovanni, G.; Celebi, M.; Clemente, P.

1990-01-01

23

Load Characteristics and Vibration Loci at the Driving Surfaces of Ultrasonic Rotary Motor using a Longitudinal-Torsional Vibration Converter  

NASA Astrophysics Data System (ADS)

Characteristics of ultrasonic rotary motors using a longitudinal-torsional vibration converter, 15 to 50 mm in diameter, are studied. To obtain a large torque, ultrasonic motors using one-dimensional longitudinal-torsional converters with diagonal slits are proposed. The converters have simple and tough structures and are driven using only a longitudinal vibration transducer. The vibration converters are fabricated from metal materials and have diagonal slits cut along the converter circumference, adjacent to a nodal position of longitudinal vibration. The ultrasonic motors consist of a vibration converter having a driving part at its free edge, and a rotor part statically pressed to the driving surface using corned disk springs. The vibration characteristics and vibration loci at the driving surfaces of these converters and motors are measured under loaded and nonloaded conditions and at forward and reverse rotating conditions, using two laser Doppler vibrometers. Vibration locus shapes are changed according to the load conditions and frequencies. Maximum torques of over 0.2 N·m are obtained by the converters, 15 to 20 mm in diameter, and at frequencies of 56 to 65 kHz. The maximum revolution speed obtained is over 550 r.p.m. using a 15-mm-diameter motor of 56 kHz.

Tsujino, Jiromaru; Nakai, Kentaro; Sako, Kazuhide; Ikegami, Noritada; Noda, Kohsuke; Suzuki, Ryo

1998-05-01

24

Characteristics of coated copper wire specimens using high frequency ultrasonic complex vibration welding equipments.  

PubMed

Welding characteristic of thin coated copper wires were studied using 40, 60, 100 kHz ultrasonic complex vibration welding equipments with elliptical to circular vibration locus. The complex vibration systems consisted of a longitudinal-torsional vibration converter and a driving longitudinal vibration system. Polyurethane coated copper wires of 0.036 mm outer diameter and copper plates of 0.3 mm thickness and the other dimension wires were used as welding specimens. The copper wire part is completely welded on the copper substrate and the insulated coating material is driven from welded area to outsides of the wire specimens by high frequency complex vibration. PMID:15047272

Tsujino, J; Ihara, S; Harada, Y; Kasahara, K; Sakamaki, N

2004-04-01

25

Experimental forced vibration responses of test houses during the Edwards Air Force Base phase of the national sonic boom test program  

NASA Technical Reports Server (NTRS)

Experimental vibration studies were conducted on two houses to determine some of the dynamic response characteristics, resulting from sonic boom. The primary objectives of the vibration tests were to identify the mode shapes associated with the various frequencies determined from the sonic boom response data, and to obtain some basic information about the vibration behavior of buildings in general. The results are presented of forced sinusoidal vibration studies of some components of the test structures. Included are acceleration response data on selected walls, wall surface modal patterns, and vibration induced noise measurements at various locations in the test structures.

Carden, H. D.; Mayes, W. H.

1975-01-01

26

Investigation of vibrational characteristics in BBO crystals by femtosecond CARS  

NASA Astrophysics Data System (ADS)

Femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) is utilized to study the ultrafast vibrational dynamics in BBO crystals at room temperature. Time-resolved two-beam and three-beam CARS are detected. The vibrational dephasing time is analyzed and the changes of vibrational mode intensities with the polarization of pump pulses are observed.

Xia, Yuanqin; Zhao, Yang; Wang, Zi; Zhang, Sheng; Dong, Zhiwei; Chen, Deying; Zhang, Zhonghua

2012-10-01

27

Vibrational coupled cluster response theory: a general implementation.  

PubMed

The calculation of vibrational contributions to molecular properties using vibrational coupled cluster (VCC) response theory is discussed. General expressions are given for expectation values, linear response functions, and transition moments. It is shown how these expressions can be evaluated for arbitrary levels of excitation in the wave function parameterization as well as for arbitrary coupling levels in the potential and property surfaces. The convergence of the method is assessed by benchmark calculations on formaldehyde. Furthermore, excitation energies and infrared intensities are calculated for the fundamental vibrations of furan using VCC limited to up to two-mode and up to three-mode excitations, VCC[2] and VCC[3], as well as VCC with full two-mode and approximate three-mode couplings, VCC[2pt3]. PMID:21303104

Seidler, Peter; Sparta, Manuel; Christiansen, Ove

2011-02-01

28

Rocket Launch-Induced Vibration and Ignition Overpressure Response  

NASA Technical Reports Server (NTRS)

Rocket-induced vibration and ignition overpressure response environments are predicted in the low-frequency (5 to 200 hertz) range. The predictions are necessary to evaluate their impact on critical components, structures, and facilities in the immediate vicinity of the rocket launch pad.

Caimi, Raoul E.; Margashayam, Ravi N.; Nayfeh, Jamal F.; Thompson, Karen (Technical Monitor)

2001-01-01

29

Modeling and simulation of truck with random vibration response  

Microsoft Academic Search

Taking a two-axle truck for research object, a mathematic model and FEA model of 10 degrees of freedom finished automobile are established to describe the vibration of the truck. Virtual excitation of road is constructed through the basic theory of virtual excitation method and its statistical properties of the actual response are obtained. FEM theory is used in discrete the

Wu Yong-hai; Fan Qin-man

2011-01-01

30

Techniques for obtaining subjective response to vertical vibration  

NASA Technical Reports Server (NTRS)

Laboratory experiments were performed to validate the techniques used for obtaining ratings in the field surveys carried out by the University College of Swansea. In addition, attempts were made to evaluate the basic form of the human response to vibration. Some of the results obtained by different methods are described.

Clarke, M. J.; Oborne, D. J.

1975-01-01

31

Vibration characteristics of OH-58A helicopter main rotor transmission  

NASA Technical Reports Server (NTRS)

Experimental vibration tests covering a range of torque and speed conditions were performed on the OH-58A helicopter main rotor transmission at the NASA Lewis Research Center. Signals from accelerometers located on the transmission housing were analyzed by using Fourier spectra, power spectral density functions, and averaging techniques. Most peaks of the Fourier spectra occurred at the spiral bevel and planetary gear mesh harmonics. The highest level of vibration occurred at the spiral bevel meshing frequency. Transmission speed and vibration measurement location had a significant effect on measured vibration; transmission torque and measurement direction had a small effect.

Lewicki, David G.; Coy, John J.

1987-01-01

32

Vibration characteristics of an APS lab facility in Building 401  

SciTech Connect

The vibratory behavior of a lab facility located in Building 401 of the Advanced Photon Source site at Argonne National Laboratory is summarized. Measurements of ambient vibration indicate that acceptable displacement levels are usually maintained (rms value below 0.1 microns) for the measured frequency range, above 0.2 Hz. An exception occurs when strong wind conditions excite a horizontal building resonance near 1.85 Hz to rms levels as high as 0.3 microns. Measurements of the laboratory floor`s dynamic response to directly applied force excitation agree with theoretical predictions. The primary component of the floor construction is a reinforced concrete slab. The slab has a transverse fundamental resonant frequency of 18.5 Hz and an associated damping level of roughly 8.5% of critical. It is also shown via experimental measurements that the linoleum surface adhered to the concrete slab is far more compliant than the slab itself and can significantly influence the floor`s dynamic response to local excitations.

Royston, T.J.

1998-01-01

33

Vibration characteristic analysis method for the quartz microgyroscope based on the admittance circle  

NASA Astrophysics Data System (ADS)

The vibration characteristic analysis method for a quartz microgyroscope based on the admittance circle is reported in this paper. Admittance theory is introduced and the admittance circle principle is analysed to study the vibration characteristics of the quartz microgyroscope. The prototype gyroscope was fabricated by micro-electromechanical systems (MEMS) technology. The admittance and phase diagram of the work mode were obtained by vibration mode test systems. Then the admittance circle of the work mode was drawn, and the parameter identification of the transfer function between the voltage and current was completed to analyse the vibration characteristics. Therefore, the vibration characteristic analysis method based on the admittance circle can be used to build the transfer function of the quartz microgyroscope, which is helpful for the design of a high performance quartz microgyroscope.

Wang, Haoxu; Dong, Peitao; Xie, Liqiang; Wu, Xuezhong

2014-03-01

34

Semiclassical nonlinear response functions for coupled anharmonic vibrations  

SciTech Connect

Observables in linear and nonlinear infrared spectroscopy may be computed from vibrational response functions describing nuclear dynamics on a single electronic surface. We demonstrate that the Herman-Kluk (HK) semiclassical approximation to the quantum propagator yields an accurate representation of quantum coherence effects in linear and nonlinear response functions for coupled anharmonic oscillators. A considerable numerical price is paid for this accuracy; the calculation requires a multidimensional integral over a highly oscillatory integrand that also grows without bound as a function of evolution times. The interference among classical trajectories in the HK approximation produces quantization of good action variables. By treating this interference analytically, we develop a mean-trajectory (MT) approximation that requires only the propagation of classical trajectories linked by transitions in action. The MT approximation accurately reproduces coherence effects in response functions of coupled anharmonic oscillators in a regime in which the observables are strongly influenced by these interactions among vibrations.

Gruenbaum, Scott M.; Loring, Roger F. [Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853 (United States)

2009-11-28

35

Welding Characteristics of Ultrasonic Wire Bonding Using High-Frequency Vibration Systems  

NASA Astrophysics Data System (ADS)

Welding characteristics of ultrasonic wire bonding using 60 kHz and 90 kHz complex vibration as well as 120 kHz linear vibration welding systems are studied. The locus shapes of the complex vibration welding tip are controlled from linear to elliptical or circular. Aluminum wire specimens of 0.1 mm diameter are welded successfully using the welding equipment. The required vibration amplitudes of these complex vibration systems are about one-half to one-third and required weld time is shorter than those for a conventional system of linear vibration. The required vibration velocity of a higher-frequency system is smaller than that of a lower-frequency system.

Tsujino, Jiromaru; Mori, Takahiro; Onozato, Takashi; Hasegawa, Koichi

1993-05-01

36

Experimental measurements of the Space Shuttle main engine fuel and oxygen turbopump vibration characteristics  

NASA Technical Reports Server (NTRS)

The vibration characteristics of the SSME (Space Shuttle main engine) are dealt with. The Space Shuttle engine consists of a main rocket nozzle and attached to it are high pressure fuel and oxygen pumps. Various vibration problems have been encountered with both the hydrogen and oxygen pumps. The vibration spectrum of the hydrogen and oxygen pumps has been analyzed by various techniques using synchronous tracking filters and FFT analyzers. The experimental data has been correlated to theoretical predictions of resonance frequencies.

Gunter, E. J.; Flack, R. D.

1981-01-01

37

Vibrational cooling and thermoelectric response of nanoelectromechanical systems  

NASA Astrophysics Data System (ADS)

An important goal in nanoelectromechanics is to cool the vibrational motion, ideally to its quantum ground state. Cooling by an applied charge current is a particularly simple and hence attractive strategy to this effect. Here we explore this phenomenon in the context of the general theory of thermoelectrics. In linear response, this theory describes thermoelectric refrigerators in terms of their cooling efficiency ? and figure of merit ZT. We show that both concepts carry over to phonon cooling in nanoelectromechanical systems. As an important consequence, this allows us to discuss the efficiency of phonon refrigerators in relation to the fundamental Carnot efficiency. We illustrate these general concepts by thoroughly investigating a simple double-quantum-dot model with the dual advantage of being quite realistic experimentally and amenable to a largely analytical analysis theoretically. Specifically, we obtain results for the efficiency, the figure of merit, and the effective temperature of the vibrational motion in two regimes. In the quantum regime in which the vibrational motion is fast compared to the electronic degrees of freedom, we can describe the electronic and phononic dynamics of the model in terms of master equations. In the complementary classical regime of slow vibrational motion, the dynamics is described in terms of an appropriate Langevin equation. Remarkably, we find that the efficiency can approach the maximal Carnot value in the quantum regime, with large associated figures of merit. In contrast, the efficiencies are typically far from the Carnot limit in the classical regime. Our theoretical results should provide guidance to implementing efficient vibrational cooling of nanoelectromechanical systems in the laboratory.

Arrachea, Liliana; Bode, Niels; von Oppen, Felix

2014-09-01

38

Welding Characteristics of Ultrasonic Wire Bonding Using High-Frequency Vibration Systems  

NASA Astrophysics Data System (ADS)

Welding characteristics of ultrasonic wire bonding using 60 kHz, 90 kHz and 120 kHz complex vibration as well as 190 kHz linear vibration welding systems are studied. The locus shapes of the complex vibration welding tip are controlled from linear to elliptical or circular. Aluminum wire specimens of 0.1 mm diameter are welded successfully using complex and high-frequency welding equipment. The required vibration amplitudes of these complex vibration systems are about one-half to one-third and required weld time is shorter than those of a conventional system of linear vibration. The required vibration velocity of a high-frequency system is lower than that of a low-frequency system. The deformations of the welded specimens under adequate welding conditions are almost the same, even if the welding tip vibration locus is altered from linear to elliptical or circular, or the vibration frequency used is changed from 60 kHz to 190 kHz in the case where the same wire specimens are used. Using these methods, the weld strength of wire bonding becomes independent of the difference in the directions of the welding tip vibration and wire length.

Tsujino, Jiromaru; Mori, Takahiro; Hasegawa, Koichi

1994-05-01

39

Influence of the Asymmetry of Static Loads on the Vibration Characteristics of Planetary Gearings  

Microsoft Academic Search

A model of planetary double-reduction gearing is used to study how the asymmetry of dynamical loads affects its vibration characteristics. Design methods for reducing the asymmetry of static loads are shown to be efficient

É. L. Airapetov; V. I. Aparkhov; I. A. Bednyi; M. Yu. Leont'ev

2003-01-01

40

Responses of primary endings of cat muscle spindles to locally applied vibration  

Microsoft Academic Search

Responses of muscle spindles in the cat soleus muscle have been studied during vibration applied locally to the belly of the muscle. Bursts of vibration at 170 Hz and with a peak amplitude of 200 µm were applied to a site at which local pressure initiated impulses from the spindle. The response to vibration depended on the conditioning of the

D. L. Morgan; U. Proske; J. E. Gregory

1991-01-01

41

The effects of whole-body vibration on human biodynamic response.  

PubMed

The objective of vibration research at the Armstrong Laboratory includes the expansion and improvement of the measurement, quantification, analysis, and modeling of human vibration response. The driving-point impedance and transmissibility techniques have been expanded and are rigorously applied in the research efforts. Driving-point impedance is defined as the ratio between the transmitted force and input velocity at the point of load application. Transmissibility is typically defined as the ratio between the acceleration level measured at some location on the body and the input acceleration at the seat. These two ratios are used to assess the magnitude and frequency location of resonance behaviors where maximum motions occur in the body. From these data, analytical models are developed which can simulate the motions and coupling behaviors, and predict the stiffness and damping characteristics of the affected anatomical structures. The ultimate goal of the research is to provide new and improved data and modeling capability for revising exposure standards and for developing equipment design guidelines and criteria for improving tolerance and reducing physiological consequences. This paper describes the results of recent studies conducted to identify the biodynamic behavior of major anatomical structures affected by seated whole-body vibration, to develop an analytical model for simulating human vibration response, and to apply the model to evaluate the effects of seat cushion materials on the transmission/attenuation pathways. PMID:11538949

Smith, S D

1995-01-01

42

Modal characteristics of in-plane vibration of circular plates clamped at the outer edge.  

PubMed

The equations of in-plane vibration in thin flat plates are solved for free vibration in circular plates clamped at the outer edge. The mode shapes are represented by trigonometric functions in the circumferential direction and by series summation of Bessel functions in the radial direction. Accuracy of the predictions of natural frequencies and mode shapes is assessed by comparisons with finite-element predictions and with previously reported results. The present solution gives very accurate predictions. The work also highlights the nature of coupling between the different circumferential and radial modes and the response of different vibrational modes at the center of the plate. It is shown that the center point of the plate vibrates only for modes with unity circumferential wave number (number of nodal diameters). Nondimensional frequency parameters are listed and the radial mode shapes of natural vibration are depicted to illustrate the free-vibration behavior in the frequency range of practical interest. PMID:12703705

Farag, N H; Pan, J

2003-04-01

43

Non-linear torsional vibration characteristics of an internal combustion engine crankshaft assembly  

NASA Astrophysics Data System (ADS)

Crankshaft assembly failure is one of the main factors that affects the reliability and service life of engines. The linear lumped mass method, which has been universally applied to the dynamic modeling of engine crankshaft assembly, reveals obvious simulation errors. The nonlinear dynamic characteristics of a crankshaft assembly are instructionally significant to the improvement of modeling correctness. In this paper, a general expression for the non-constant inertia of a crankshaft assembly is derived based on the instantaneous kinetic energy equivalence method. The nonlinear dynamic equations of a multi-cylinder crankshaft assembly are established using the Lagrange rule considering nonlinear factors such as the non-constant inertia of reciprocating components and the structural damping of shaft segments. The natural frequency and mode shapes of a crankshaft assembly are investigated employing the eigenvector method. The forced vibration response of a diesel engine crankshaft assembly taking into account the non-constant inertia is studied using the numerical integral method. The simulation results are compared with a lumped mass model and a detailed model using the system matrix method. Results of non-linear torsional vibration analysis indicate that the additional excitation torque created by non-constant inertia activates the 2nd order rolling vibration, and the additional damping torque resulting from the non-constant inertia is the main nonlinear factor. The increased torsional angular displacement evoked by the high order excitation torque relates to the non-constant inertia. This research project is aimed at improving nonlinear dynamics theory, and the confirmed nonlinear parameters can be used for the structure design of a crankshaft assembly.

Huang, Ying; Yang, Shouping; Zhang, Fujun; Zhao, Changlu; Ling, Qiang; Wang, Haiyan

2012-07-01

44

Vibration Characteristics of a Vertical Round Tube According to Heat Transfer Regimes  

SciTech Connect

This paper presents the results of an experimental work on the effects of boiling heat transfer regimes on the flow-induced vibration (FIV). The experiment has been performed using an electrically heated vertical round tube through which water flows at atmospheric pressure. Vibration characteristics of the heated tube are changed significantly by heat transfer regimes and flow patterns. For single-phase liquid convection, the rod vibrations are negligible. However, on the beginning of subcooled nucleate boiling at tube exit, vibration level becomes very large. As bubble departure occurs at the nucleation site of heated surface, the vibration decreases to saturated boiling region where thermal equilibrium quality becomes 0.0 at tube exit. In saturated boiling region, vibration amplitude increases with exit quality up to a certain maximum value due to the reinforced turbulence then decreases. At liquid film dryout condition, vibration could be regarded as negligible, however, these results cannot be extended to DNB-type CHF mechanism. Frequency analysis results of vibration signals suggested that excitation sources be different with heat transfer regimes. This study would contribute to improve the understanding of the relationship between boiling heat transfer and FIV. (authors)

Yong Ho Lee; Soon Heung Chang [Korea Advanced Institute of Science and Technology, 373-1, Guseung-dong, Yuseong-ku, Daejeon, 305-701 (Korea, Republic of); Won-Pil Baek [Korea Atomic Energy Research Institute, 150, Dukjin-Dong, Yusong-Gu, Taejon 305-353 (Korea, Republic of)

2002-07-01

45

The effect of vibration on the hemorheological characteristics of non-aggregated blood  

Microsoft Academic Search

The present study investigates the hemorheological characteristics of blood flow with applying vibration to a non-aggregating\\u000a red blood cell suspension. In order to obtain the non-aggregating RBC suspension, blood samples were treated with vibration\\u000a at a specified condition, which viscosities were taken before and after the treatment, respectively. The viscosity of the\\u000a blood samples after treatment was higher than before

Sehyun Shin; Yun-Hee Ku; Su-Yeon Moon; Jang-Soo Suh

2003-01-01

46

Vibration and Noise Characteristics of Elliptical Gears due to Non-Uniform Rotation  

NASA Astrophysics Data System (ADS)

Elliptical gear is a typical non-circular gear, which transmits a variable-ratio rotation and power simultaneously. Due to the non-uniform rotation, the vibration and noise of elliptical gears demonstrate particular characteristics which should be paid attention to in practical application. In this paper, two elliptical gears, which are a single elliptical gear and a double elliptical gear, have been investigated to analyze the vibration and noise characteristics of elliptical gears. The corresponding circular gears for comparison are also investigated. General factors including the torque, the rotation speed, the gear vibration acceleration and the gear noise of the four test gears are measured by running test. The root mean square of the Circumferential Vibration Acceleration (CVA) and the sound pressure level of the noise of elliptical gears are obtained from the measured results and compared with those of circular gears to clarify the vibration and noise characteristics of elliptical gears. Furthermore, the frequency analysis of the CVA of elliptical gears is conducted by Fast Fourier Transform Algorithm (FFT) and compared with that of circular gears. The main vibration component of elliptical gear is uncovered according to the obtained frequency spectra. In addition, the Critical Rotation Speeds of Tooth Separation (CRSTS) of elliptical gear is obtained and its relation with load torque is unveiled.

Liu, Xing; Nagamura, Kazuteru; Ikejo, Kiyotaka

47

The acute effect of vibration exercise on concentric muscular characteristics.  

PubMed

This study was designed to compare the acute effect of vibration exercise with a concentric-only activity (arm cranking) on concentric-only muscle action using an upper body isoinertial exercise. Twelve healthy, physically active men, 30.0y+/-6.1 (mean+/-S.D.); height 1.81m+/-0.06; and weight 83.4kg+/-9.7, performed four maximal prone bench pull (PBP) efforts before and after a 5-min period of three different interventions: (1) acute vibration exercise (VBX); (2) arm cranking (AC); and (3) control (no exercise) (NVBX). Electromyography (EMG) activity was assessed from the middle trapezius muscle during PBP. Acute VBX was induced with an electric-powered dumbbell (DB) (frequency 26Hz, amplitude 3mm), with 30-s exposures at five different shoulder positions. NVXB was performed with the participants holding the DB with the machine turned off, and AC was performed at 25W. There was a significant (intervention x pre-post) interaction such that acute VBX and AC enhanced peak power by 4.8% (p<0.001) and 3.0% (p<0.001), respectively, compared to NVBX (-2.7%). However, there was no effect of any treatments on EMG activity compared to the control. In conclusion, acute VBX provides an acute ergogenic effect which potentiates concentric-only muscle performance, though not to a significantly greater extent than concentric (arm cranking) exercise. PMID:17714990

Cochrane, D J; Stannard, S R; Walmsely, A; Firth, E C

2008-11-01

48

Vibration testing based on impulse response excited by laser ablation  

NASA Astrophysics Data System (ADS)

This paper proposes an innovative vibration testing method based on impulse response excited by laser ablation. In conventional vibration testing using an impulse hammer, high-frequency elements of over tens of kilohertz are barely present in the excitation force. A pulsed high-power YAG laser is used in this study for producing an ideal impulse force on a structural surface. Illuminating a point on a metal with the well-focused YAG laser, laser ablation is caused by generation of plasma on the metal. As a result, an ideal impulse excitation force generated by laser ablation is applied to the point on the structure. Therefore, it is possible to measure high-frequency FRFs due to the laser excitation. A water droplet overlay on the metal is used to adjust the force magnitude of laser excitation. An aluminum block that has nine natural frequencies below 40 kHz is employed as a test piece. The validity of the proposed method is verified by comparing the FRFs of the block obtained by the laser excitation, impulse hammer, and finite element analysis. Furthermore, the relationship between accuracy of FRF measurements and sensitivity of sensors is investigated.

Kajiwara, Itsuro; Hosoya, Naoki

2011-10-01

49

Sensitivity analysis of torsional vibration characteristics of helicopter rotor blades. Part 1: Structural dynamics analysis  

NASA Technical Reports Server (NTRS)

A theoretical investigation of structural vibration characteristics of rotor blades was carried out. Coupled equations of motion for flapwise bending and torsion were formulated for rotor blades with noncollinear elastic and mass axes. The finite element method was applied for a detailed representation of blade structural properties. Coupled structural mass and stiffness coefficients were evaluated. The range of validity of a set of coupled equations of motion linearized with respect to eccentricity between elastic and mass axes was investigated. The sensitivity of blade vibration characteristics to torsion were evaluated by varying blade geometric properties, boundary conditions, and eccentricities between mass and elastic axes.

Bratanow, T.; Ecer, A.

1974-01-01

50

Influence of vibration on the wave characteristics of a liquid film  

SciTech Connect

The influence of vibrations on the wave characteristics of a liquid film is investigated experimentally under annular mist flow conditions for a horizontal tube of diameter 12 mm. The results of measurements of the distribution of the film thickness around the circumference of the tube and the wave velocity on the surface of the liquid film are generalized by appropriate empirical relations. The data indicate that vibration has a significant influence on the wave characteristics and, accordingly, on the thickness of the liquid film at the wall. This fact must be taken into consideration in the design of power equipment.

Gudushauri, E.G.; Medvedev, A.E.; Selifanov, I.V.; Berodze, M.I.

1988-07-01

51

Structural damage detection using cross correlation functions of vibration response  

NASA Astrophysics Data System (ADS)

Structural damage detection methods based on vibration responses are appealing for a variety of reasons such as their potential to observe damage from sensors placed remote from an unknown damage site. Of particular interest to the authors is online damage detection in which changes in the structure can be flagged up in an automated fashion by permanently installed transducers. In a previous paper by the authors, the inner product vector (IPV) was proposed as a damage detection algorithm which uses cross correlation functions between response measurements. Implicitly assumed in the formulation is that the response quantity is that of displacement resulting from white noise excitation. In this paper, the IPV technique is first reviewed and then generalised to address velocity and acceleration response to band pass white noise excitation. It is shown that the IPV is a weighted summation of the mode shapes, and the effect of some particular measurement noise on the IPV can be adaptively eliminated in the calculation of IPV. Then, the damage detection method based on changes in the IPV is proposed. Finally, damage detection experiments of shear frame structure, honeycomb sandwich composite beam and aircraft stiffened panel are presented to illustrate the feasibility and effectiveness of the proposed method.

Wang, Le; Yang, Zhichun; Waters, T. P.

2010-11-01

52

Vibration Characteristics of Piezoelectric Lead Zirconate Titanate by Fluid Flow in Intravascular Oxygenator  

NASA Astrophysics Data System (ADS)

In this paper, we describe the enhancement in oxygen transfer rate in hollow-fiber-membrane (HFM) modules using a plumbum piezoelectric lead zirconate titanate (PZT) actuator and a piezoelectric poly vinylidene fluoride (PVDF) sensor. We developed a vibrating intravascular lung assist device (VIVLAD) for patients having chronic respiratory problems and performed experiments on hydrodynamic flow through a bundle of sinusoidal vibrating hollow fibers. These modules were used to provide some insight into how wall vibrations might enhance the performance of an intravascular lung assist device. The experimental design and procedure are then applied to the fabrication of a device used to assess the effectiveness of membrane vibrations. The test section was a cylindrical duct with an inner diameter of 30 mm. The flow rate was controlled by a pump and monitored by a built-in flowmeter. The vibration apparatus was composed of a piezovibrator, a function generator, and a power amplifier. The direction of vibration was radial to the fluid flow. Gas flow rates of up to 6 L/min through 120-cm-long hollow fibers were achieved by exciting the piezovibrator. The time and frequency responses of PVDF sensors were investigated through various frequencies in VIVLAD. In these devices, the flow of blood and the source of oxygen were separated by a semipermeable membrane that allows oxygen and carbon dioxide to diffuse into and out of the fluid, respectively. Results of the experiments have shown that a vibrating intravascular lung assist device performs effectively.

Kim, Gi?Beum; Hong, Chul?Un; Kwon, Tae?Kyu

2006-04-01

53

Effect of vibration on retention characteristics of screen acquisition systems. [for surface tension propellant acquisition  

NASA Technical Reports Server (NTRS)

The design of surface tension propellant acquisition systems using fine-mesh screen must take into account all factors that influence the liquid pressure differentials within the system. One of those factors is spacecraft vibration. Analytical models to predict the effects of vibration have been developed. A test program to verify the analytical models and to allow a comparative evaluation of the parameters influencing the response to vibration was performed. Screen specimens were tested under conditions simulating the operation of an acquisition system, considering the effects of such parameters as screen orientation and configuration, screen support method, screen mesh, liquid flow and liquid properties. An analytical model, based on empirical coefficients, was most successful in predicting the effects of vibration.

Tegart, J. R.; Aydelott, J. C.

1978-01-01

54

Methods for deriving a representative biodynamic response of the hand-arm system to vibration  

NASA Astrophysics Data System (ADS)

Vibration-induced biodynamic responses (BR) of the human hand-arm system measured with subjects participating in an experiment are usually arithmetically averaged and used to represent their mean response. The mean BR data reported from different studies are further arithmetically averaged to form the reference mean response for standardization and other applications. The objectives of this study are to clarify whether such a response-based averaging process could significantly misrepresent the characteristics of the original responses, and to identify an appropriate derivation method. The arithmetically averaged response was directly compared with the response derived from a property-based method proposed in this study. Two sets of reported mechanical impedance data measured at the fingers and the palms of the hands were used to derive the models required for the comparison. This study found that the response-based arithmetic averaging could generate some systematic errors. The range of the subjects' natural frequencies in each resonance mode, the mode damping ratio, and the number of subjects participating in the experiment are among the major factors influencing the level of the errors. An effective and practical approach for reducing the potential for error is to increase the number of subjects in the BR measurement. On the other hand, the property-based derivation method can be generally used to obtain the representative response, but it is less efficient than the response-based derivation method.

Dong, Ren G.; Welcome, Daniel E.; McDowell, Thomas W.; Wu, John Z.

2009-09-01

55

Acceleration response spectrum for predicting floor vibration due to occupant walking  

NASA Astrophysics Data System (ADS)

Annoying vibrations caused by occupant walking is an important serviceability problem for long-span floors. At the design stage the floor's structural arrangement may frequently change to cater for the owner's varying requirements. An efficient and accurate approach for predicting a floor's acceleration response is thus of great significance. This paper presents a design-oriented acceleration response spectrum for calculating a floor's response given the floor's modal characteristics and a specified confidence level. 2204 measured footfall traces from 61 test subjects were used to generate 10 s peak root-mean-square acceleration response spectra, on which a piecewise mathematical representation is based. The proposed response spectrum consists of three main parts: the first harmonic plateau ranging from 1.5 to 2.5 Hz, the second harmonic plateau ranging from 3.0 to 5.0 Hz and the descending part going with frequencies from 5.0 to 10.0 Hz. The representative value of each plateau and the mathematical representation for the descending curve were determined statistically for different confidence levels. Furthermore, the effects of factors, such as floor span, occupant stride length, higher modes of vibration, boundary conditions and peak acceleration response, on the proposed spectrum have been investigated and a modification measure for each factor is suggested. A detailed application procedure for the proposed spectrum approach is presented and has been applied to four existing floors to predict their acceleration responses. Comparison between predicted and field measured responses shows that the measured accelerations of the four floors are generally close to or slightly higher than the predicted values for the 75 percent confidence level, but are all lower than the predicted values for the 95 percent confidence level. Therefore the suggested spectrum-based approach can be used for predicting a floor's response subject to a single person walking.

Chen, Jun; Xu, Ruotian; Zhang, Mengshi

2014-07-01

56

Differences in the human response to freight and passenger railway vibration in residential environments.  

PubMed

The aim of this paper is to quantify and investigate differences in the human response to freight and passenger railway environmental vibration. Data for this research comes from a field study comprising interviews with respondents and measurements of their vibration exposure (N = 752). A logistic regression model has been developed to classify measured railway vibration signals in the field study as freight or passenger signals, with a classification accuracy of 96%. Exposure-response relationships for annoyance due to exposure to freight and passenger railway vibration are then determined using an ordinal probit model with fixed thresholds. These exposure response relationships indicate that the annoyance response for exposure to freight railway vibration is significantly higher than that for passenger railway vibration. In terms of a community tolerance level, the population studied is 15 dB (re 10(-6) m s(-2)) more tolerant to passenger railway vibration than freight railway vibration. The potential reasons for this difference in the human response are investigated and discussed. Some of the factors that are investigated include time of day effects, sleep disturbance, effects of combined noise and vibration and the effects of social, attitudinal, and demographic factors. PMID:25235567

Sharp, Calum; Woodcock, James; Peris, Eulalia; Moorhouse, Andrew; Waddington, David

2014-04-01

57

Light-induced vibration characteristics of free-standing carbon nanotube films fabricated by vacuum filtration  

NASA Astrophysics Data System (ADS)

In this paper, we fabricated carbon nanotube (CNT) films with different thickness by vacuum filtration method, and the films were separated from Mixed Cellulose Ester membranes with burn-off process. The thickness of CNT films with different concentrations of CNTs 50 mg, 100 mg, 150 mg, and 200 mg are 10.36 ?m, 20.90 ?m, 30.19 ?m, and 39.98 ?m respectively. The CNT bundles are homogeneously distributed and entangled with each other, and still maintain 2D continuous network structures after burn-off process. The optical absorptivity of the films is between 84% and 99% at wavelengths ranging from 400 nm to 2500 nm. Vibration characteristics were measured with the Fabry-Perot (F-P) interferometer vibration measurement system. CNT films vibrate only under the xenon light irradiating perpendicularly to the surface. Vibration recorded by Fabry-Perot interferometer is considered to be caused by the time-dependent thermal moment, which is due to the temperature differences of two sides of CNT films. The vibration frequency spectrums between 0.1 ˜ 0.5 Hz were obtained by the Fast Fourier Transform spectra from time domain to frequency domain, and showed a linear relationship with films thickness, which is in accordance with theoretical model of thermal induced vibration.

Li, Junying; Zhu, Yong; Wang, Xin; Wang, Ning; Zhang, Jie

2014-07-01

58

Perforated heat exchanger surfaces. I - Flow phenomena, noise and vibration characteristics  

Microsoft Academic Search

This paper is a first part of two part series review on perforated heat exchanger surfaces. Flow phenomena, noise and vibration characteristics associated with perforated surfaces are reviewed and discussed. It is shown that beyond a certain Reynolds number, flow over a perforation becomes unstable accompanied by oscillations and vortex shedding. Flow oscillations and vortex shedding make the boundary layer

R. K. Shah

1975-01-01

59

Studies on vibration characteristics of a pear using finite element method*  

PubMed Central

The variation of the vibration characteristics of a Huanghua pear was investigated using finite element simulations. A new image processing technique was used to obtain the unsymmetrical and un-spherical geometrical model of a pear. The vibration characteristics of this type of pear with the correlation of its behavior with geometrical configurations and material characteristics were investigated using numerical modal analysis. The results showed that the eigenfrequency increased with the increasing pear Young’s modulus, while decreased with increasing pear density, and decreased with increasing pear volume. The results of this study provided foundation for further investigations of the physical characteristics of fruits and vegetables by using finite element simulations. PMID:16691644

Song, Hui-zhi; Wang, Jun; Li, Yong-hui

2006-01-01

60

The dynamic characteristics of harvesting energy from mechanical vibration via piezoelectric conversion  

NASA Astrophysics Data System (ADS)

As an alternative power solution for low-power devices, harvesting energy from the ambient mechanical vibration has received increasing research interest in recent years. In this paper we study the transient dynamic characteristics of a piezoelectric energy harvesting system including a piezoelectric energy harvester, a bridge rectifier, and a storage capacitor. To accomplish this, this energy harvesting system is modeled, and the charging process of the storage capacitor is investigated by employing the in-phase assumption. The results indicate that the charging voltage across the storage capacitor and the gathered power increase gradually as the charging process proceeds, whereas the charging rate slows down over time as the charging voltage approaches to the peak value of the piezoelectric voltage across the piezoelectric materials. In addition, due to the added electrical damping and the change of the system natural frequency when the charging process is initiated, a sudden drop in the vibration amplitude is observed, which in turn affects the charging rate. However, the vibration amplitude begins to increase as the charging process continues, which is caused by the decrease in the electrical damping (i.e., the decrease in the energy removed from the mechanical vibration). This electromechanical coupling characteristic is also revealed by the variation of the vibration amplitude with the charging voltage.

Fan, Kang-Qi; Ming, Zheng-Feng; Xu, Chun-Hui; Chao, Feng-Bo

2013-10-01

61

Piezoelectric Instruments of High Natural Frequency Vibration Characteristics and Protection Against Interference by Mass Forces  

NASA Technical Reports Server (NTRS)

The exploration of the processes accompanying engine combustion demands quick-responding pressure-recording instruments, among which the piezoelectric type has found widespread use because of its especially propitious properties as vibration-recording instruments for high frequencies. Lacking appropriate test methods, the potential errors of piezoelectric recorders in dynamic measurements could only be estimated up to now. In the present report a test method is described by means of which the resonance curves of the piezoelectric pickup can be determined; hence an instrumental appraisal of the vibration characteristics of piezoelectric recorders is obtainable.

Gohlka, Werner

1943-01-01

62

Dynamic characteristics of a base isolated building from ambient vibration measurements and low level earthquake shaking  

Microsoft Academic Search

Ambient vibration tests were conducted on a base-isolated apartment building in Takamatsu, Japan, to determine the mode shapes and the associated natural frequencies and damping ratios at very low levels of excitation. The latest developments in signal analysis for modal decomposition are used to analyze the ambient response data. A finite element model of the building and isolators was calibrated

C. E Ventura; W. D Liam Finn; J.-F Lord; N Fujita

2003-01-01

63

Nonlinear characteristics of vortex-induced vibration at low Reynolds number  

NASA Astrophysics Data System (ADS)

Numerical simulations of vortex-induced vibration of a two-dimensional elastic circular cylinder under the uniform flow are calculated when Reynolds number is 200. In order to achieve the vortex-induced vibration, two-dimensional incompressible Navier-Stokes equations are solved with the space-time finite element method, the equations of the cylinder motion are solved with the new explicit integral method and the emeshing is achieved by the spring analogy technology. Considering vortex-induced vibration with the low reduced damping parameters, the variety trends of the lift coefficient, the drag coefficient, the displacement of cylinder are analyzed under different oscillating frequencies of cylinder. The nonlinear phenomena of locked-in, beat and phaseswith are captured successfully. The limit cycle and bifurcation of lift coefficient and displacement are analyzed. Besides, the Poincare sections of the lift coefficient are used for discussing the bifurcation of periodic solution. There are some differences in nonlinear characteristics between the results of the one degree of freedom cylinder model and those of the two degrees of freedom cylinder model. The streamwise vibration has a certain effect on the lateral vibration.

Li, Tian; Zhang, Jiye; Zhang, Weihua

2011-07-01

64

Vibration behavior and response to an accidental collision of SFT prototype in Qiandao Lake (China)  

Microsoft Academic Search

This article presents free vibration analysis of the submerged floating tunnel (SFT) prototype, which has been designed to be built in Qiandao Lake (China). As an approximation the supporting effect of the tethers is omitted in the calculation of beam-like bending vibrations. As a case study, the response of the SFT prototype to an accidental collision by an object like

Shuangyin Zhang; Lei Wang; Youshi Hong

2010-01-01

65

Modal vibration response measurements for characterization of composite materials and structures  

Microsoft Academic Search

This paper summarizes recent research by the author, his colleagues and graduate students on the use of modal vibration response measurements to characterize, quickly and accurately the mechanical properties of fiber-reinforced composite materials and structures. It is shown that modal testing in either a single mode or multiple modes of vibration can be used to determine elastic moduli and damping

Ronald F. Gibson

2000-01-01

66

Insulation of nonlinear and random vibrations in the mining industry. [elastodynamic response of rubber insulator  

NASA Technical Reports Server (NTRS)

The insulation of nonlinear and random vibrations is considered for some ore preparing and sorting implements: rotary crushers, resonance screens, hammer mills, etc. The appearance of subharmonic vibrations is analyzed, and the conditions for their appearance are determined. A method is given for calculating the insulation of these vibrations by means of elastic elements made of rubber. The insulation of the random vibrations produced by Symons crushers is calculated by determining the transmissability and deformation of the insulation system for a narrow band random response.

Zeveleanu, C.

1974-01-01

67

Mechanical and Vibration Characteristics of Laminated Composite Plates Embedding Shape Memory Alloy Superelastic Wires  

NASA Astrophysics Data System (ADS)

Currently, there is a great interest in the study of shape memory alloy (SMA) composites, since SMA wires with a small diameter have become commercially available. Many potential uses have been found for SMA composites in shape control, vibration control, and for the realization of structures with improved damage tolerance. In this work, two types of SMA-hybridized composites are presented for investigating the mechanical and vibration characteristics. The first one contains unidirectional superelastic SMA wires, while the other has been realized with embedded knitted SMA layers. The samples from these laminates have been tested according to “Charpy method” (ASTM D256) and static flexural test method (ASTM D790) to evaluate the influence of the integration of thin superelastic SMA wires on the impact behavior and the mechanical properties of the hybrid composites. Moreover, since the SMA wires are expected to give damping capacity, by measuring the vibration mode of a clamped cantilever using laser vibrometry, the influence of both SMA arrangements on the vibration characteristics has been investigated. Finally, further tests have been carried out on composite panels realized by embedding unidirectional steel wires to distinguish the influence of the martensitic transformation from the pure introduction of a metallic wire into the polymeric matrix.

Pappadà, Silvio; Gren, Per; Tatar, Kourosh; Gustafson, Tord; Rametta, Rocco; Rossini, Ettore; Maffezzoli, Alfonso

2009-08-01

68

Optimisation of the vibrational response of ultrasonic cutting systems  

NASA Astrophysics Data System (ADS)

This paper provides an account of an investigation into possible dynamic interactions between two coupled non-linear sub-systems, each possessing opposing non-linear overhang characteristics in the frequency domain in terms of positive and negative cubic stiffnesses. This system is a two-degree-of-freedom Duffing oscillator in which certain non-linear effects can be advantageously neutralised under specific conditions. This theoretical vehicle has been used as a preliminary methodology for understanding the interactive behaviour within typical industrial ultrasonic cutting components. Ultrasonic energy is generated within a piezoelectric exciter, which is inherently non-linear, and which is coupled to a bar- or block-horn, and to one or more material cutting blades, for example. The horn/blade configurations are also non-linear, and within the whole system there are response features which are strongly reminiscent of positive and negative cubic stiffness effects. The two-degree-of-freedom model is analysed and it is shown that a practically useful mitigating effect on the overall non-linear response of the system can be created under certain conditions when one of the cubic stiffnesses is varied. It has also been shown experimentally that coupling of ultrasonic components with different non-linear characteristics can strongly influence the performance of the system and that the general behaviour of the hypothetical theoretical model is indeed borne out in practice. Further experiments have shown that a multiple horn/blade configuration can, under certain circumstances, display autoparametric responses based on the forced response of the desired longitudinal mode parametrically exciting an undesired lateral mode. Typical autoparametric response phenomena have been observed and are presented at the end of the paper.

Cartmell, M. P.; Lim, F. C. N.; Cardoni, A.; Lucas, M.

2005-10-01

69

Determination of vibration characteristics of multiple-load-path blades by a modified Galerkin's method  

NASA Astrophysics Data System (ADS)

A modified Galerkin's method is developed to determine the natural vibration characteristics of multiple-load-path rotor blades. The development follows parallel to the CAMRAD program procedure for a single-load-path blade. Two types of finite series expansion functions are utilized: exact transcendental solutions to nonrotating uniform beam problems, and polynomial functions. A computer program based on this method is developed to determine the free vibration characteristics of multiple-load-path blades undergoing coupled flapwise bending, chordwise bending, twisting and extensional motions. Numerical results are obtained for two rotors. The first has constant properties along the span and the second is modelled from a nonuniform experimental rotor with discontinuous properties. Natural frequencies compare well with those predicted using a finite element approach, and with the experimental results for the second rotor.

Lauzon, D. M.; Murthy, V. R.

1993-03-01

70

The fractal characteristic of vibration signals in different milling tool wear periods  

NASA Astrophysics Data System (ADS)

There are a wide variety of condition monitoring techniques currently used for the recognition and diagnosis of machinery faults. Tool wear often results in chaotics on milling process. Little research has been carried out about the occurrence and detection of chaotic behavior in time series signal of tool vibration. In the paper the vibration acceleration signal based on the operating stages of tool wear is established for the analysis of the correlation dimension of the operating stages of tool wear. Correlation dimension is calculated to recognize the tool wear operating conditions. Finally ,some experimental results from the fractal characteristic show that there are distinct differences in the correlation dimension in different tool wear conditions and close the correlation dimension in same tool wear conditions. The correlation dimension not only can be used as important scientific basis for monitoring tool wear, but also complement of other characteristic picking up method.

Xu, Chuangwen; Cheng, Hualing; Liu, Limei

2008-10-01

71

New Passive Control Methods for Reducing Vibrations of Rotors: Discontinuous Spring Characteristics and Ball Balancers  

Microsoft Academic Search

\\u000a This paper introduces a new passive vibration suppression method called the discontinuous spring characteristics and provides\\u000a a methods to improve the efficiency of automatic ball balancers. The former method can be used to suppress the amplitude at\\u000a a resonance and also be applied to suppress unstable oscillations of an asymmetrical shaft and a rotor partially filled with\\u000a liquid. An automatic

Yukio Ishida

72

Teacher Characteristics for Culturally Responsive Pedagogy  

ERIC Educational Resources Information Center

Culturally responsive pedagogy, as defined by one of the most prominent authors in the field, Geneva Gay (2002), is "using the cultural characteristics, experiences, and perspectives of ethnically diverse students as conduits for teaching them more effectively". Culturally responsive pedagogy can be thought of, then, as teaching practices that…

Rychly, Laura; Graves, Emily

2012-01-01

73

Vibration manual  

NASA Technical Reports Server (NTRS)

Guidelines of the methods and applications used in vibration technology at the MSFC are presented. The purpose of the guidelines is to provide a practical tool for coordination and understanding between industry and government groups concerned with vibration of systems and equipments. Topics covered include measuring, reducing, analyzing, and methods for obtaining simulated environments and formulating vibration specifications. Methods for vibration and shock testing, theoretical aspects of data processing, vibration response analysis, and techniques of designing for vibration are also presented.

Green, C.

1971-01-01

74

Responses of the frog primary vestibular afferents to direct vibration of the semicircular canal  

NASA Technical Reports Server (NTRS)

Responses of primary afferents (PA) of lateral semicircular canal to sinusoidal vibration of the canal wall within the range 0.05-200 Hz (mean amplitudes 5-15 microns) in immobilized frogs were studied. Dynamic characteristics (gain, phase) of relative linear velocity of the vibrator (micron X/s) were examined. At 0.2 Hz, the gain was 5.35 + or - 3.19 imp X/s /micron X/s (mean; S.D.; n=14) and linearly decreased if the frequency rose. Phase lag of relative velocity at 0.05 Hz was 49.8 deg + or - 16.5 deg (n=13) and at 1 Hz 97 deg + or - 9.4 deg (n=22). At 100 Hz phase lag was about 240 deg. Three groups of PA are described: wide range PA reacting in the range from 0.05 up to 60-180 Hz; high frequency PA responding in the range from 20-40 up to 100-150 Hz; and low frequency PA responding in the range from 0.05 up to 2-20 Hz.

Orlov, I. V.

1980-01-01

75

Vibration response imaging: protocol for a systematic review  

PubMed Central

Background The concept of lung sounds conveying information regarding lung physiology has been used extensively in clinical practice, particularly with physical auscultation using a stethoscope. Advances in computer technology have facilitated the construction of dynamic visual images derived from recorded lung sounds. Arguably, the most significant progress in this field was the development of the commercially available vibration response imaging (VRI) (Deep Breeze Ltd, Or-Akiva, Israel). This device provides a non-invasive, dynamic image of both lungs constructed from sounds detected from the lungs using surface sensors. In the literature, VRI has been utilized in a multitude of clinical and research settings. This systematic review aims to address three study questions relating to whether VRI can be used as an evaluative device, whether the images generated can be characterized, and which tools and measures have been used to assess these images. Methods/Design This systematic review will involve implementing search strategies in five online journal databases in order to extract articles relating to the application of VRI. Appropriate articles will be identified against a set of pre-determined eligibility criteria and assessed for methodological quality using a standardized scale. Included articles will have data extracted by the reviewers using a standardized evidence table. A narrative synthesis based on a standardized framework will be conducted, clustering evidence into three main groups; one for each of the study questions. A meta-analysis will be conducted if two or more research articles meet pre-determined criteria that allow quantitative synthesis to take place. Discussion This systematic review aims to provide a complete overview of the scope of VRI in the clinical and research settings, as well as to discuss methods to interpret the data obtained from VRI. The systematic review intends to help clinicians to make informed decisions on the clinical applicability of the device, to allow researchers to identify further potential avenues of investigation, and to provide methods for the evaluation and interpretation of dynamic and static images. The publication and registration of this review with PROSPERO provides transparency and accountability, and facilitates the appraisal of the proposed systematic review against the original design. Trial registration PROSPERO registration number: CRD42013003751 PMID:24066696

2013-01-01

76

Vibration responses of h-BN sheet to charge doping and external strain  

SciTech Connect

Based on density functional theory and density functional perturbation theory calculations, we systematically investigate the vibration responses of h-BN sheet to charge doping and external strains. It is found that under hole doping, the phonon frequencies of the ZO and TO branches at different wave vector q shift linearly with different slopes. Under electron doping, although the phonon frequencies shift irregularly, the shifting values are different at different phonon wave vectors. Interestingly, we find that external strain can restrain the irregular vibration responses of h-BN sheet to electron doping. The critical factor is revealed to be the relative position of the nearly free electron and boron p{sub z} states of h-BN sheet. Under external strains, the vibration responses of h-BN sheet are also found to be highly dependent on the phonon branches. Different vibration modes at different q points are revealed to be responsible for the vibration responses of h-BN sheet to charge doping and external strain. Our results point out a new way to detect the doping or strain status of h-BN sheet by measuring the vibration frequencies at different wave vector.

Yang, Wei; Yang, Yu; Zheng, Fawei [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)] [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Zhang, Ping, E-mail: zhang-ping@iapcm.ac.cn [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China) [Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China); Beijing Computational Science Research Center, Beijing 100084 (China)

2013-12-07

77

Vibration responses of h-BN sheet to charge doping and external strain  

NASA Astrophysics Data System (ADS)

Based on density functional theory and density functional perturbation theory calculations, we systematically investigate the vibration responses of h-BN sheet to charge doping and external strains. It is found that under hole doping, the phonon frequencies of the ZO and TO branches at different wave vector q shift linearly with different slopes. Under electron doping, although the phonon frequencies shift irregularly, the shifting values are different at different phonon wave vectors. Interestingly, we find that external strain can restrain the irregular vibration responses of h-BN sheet to electron doping. The critical factor is revealed to be the relative position of the nearly free electron and boron pz states of h-BN sheet. Under external strains, the vibration responses of h-BN sheet are also found to be highly dependent on the phonon branches. Different vibration modes at different q points are revealed to be responsible for the vibration responses of h-BN sheet to charge doping and external strain. Our results point out a new way to detect the doping or strain status of h-BN sheet by measuring the vibration frequencies at different wave vector.

Yang, Wei; Yang, Yu; Zheng, Fawei; Zhang, Ping

2013-12-01

78

Vibration and flutter characteristics of the SR7L large-scale propfan  

NASA Technical Reports Server (NTRS)

An investigation of the vibration characteristics and aeroelastic stability of the SR7L Large-Scale Advanced Propfan was performed using a finite element blade model and an improved aeroelasticity code. Analyses were conducted for different blade pitch angles, blade support conditions, number of blades, rotational speeds, and freestream Mach numbers. A finite element model of the blade was used to determine the blade's vibration behavior and sensitivity to support stiffness. The calculated frequencies and mode shape obtained with this model agreed well with the published experimental data. A computer code recently developed at NASA Lewis Research Center and based on three-dimensional, unsteady, lifting surface aerodynamic theory was used for the aeroelastic analysis to examine the blade's stability at a cruise condition of Mach 0.8 at 1700 rpm. The results showed that the blade is stable for that operating point. However, a flutter condition was predicted if the cruise Mach number was increased to 0.9.

August, Richard; Kaza, Krishna Rao V.

1988-01-01

79

Investigation of the vibrational behavior and stability characteristics of single-walled zinc sulfide nanotubes  

NASA Astrophysics Data System (ADS)

The molecular mechanics is combined here with density functional theory to develop an accurate model for single-walled zinc sulfide nanotubes. It is shown that based on the resemblance between nanotubes and space frame structures, nanotubes can be modeled as a combination of beam and mass elements. Using the developed model, the vibrational behavior and stability characteristics of single-walled zinc sulfide nanotubes with different geometries and under different boundary conditions are investigated. It is observed that the side length of nanotubes affect its vibrational behavior. However, this effect will reduce for longer nanotubes. Besides, it is shown that the stability of nanotubes have a strong dependence on geometry parameters for short nanotubes. However, for sufficiently long nanotube this dependence would diminish.

Ansari, R.; Rouhi, S.; Mirnezhad, M.

2014-10-01

80

Nondestructive Evaluation of Ceramic Candle Filters Using Vibration Response  

SciTech Connect

This study aims at the development of an effective nondestructive evaluation technique to predict the remaining useful life of a ceramic candle filter during a power plant's annual maintenance shutdown. The objective of the present on-going study is to establish the vibration signatures of ceramic candle filters at varying degradation levels due to different operating hours, and to study the various factors involving the establishment of the signatures.

Chen, Roger H. L.; Kiriakidis, Alejandro C.; Peng, Steve W.

1997-07-01

81

Variation in Neuromuscular Responses during Acute Whole-Body Vibration Exercise  

Microsoft Academic Search

ABERCROMBY, A. F. J., W. E. AMONETTE, C. S. LAYNE, B. K. MCFARLIN, M. R. HINMAN, and W. H. PALOSKI. Variation in Neuromuscular Responses during Acute Whole-Body Vibration Exercise. Med. Sci. Sports Exerc., Vol. 39, No. 9, pp. 1642-1650, 2007. Purpose: Leg muscle strength and power are increased after whole-body vibration (WBV) exercise. These effects may result from increased neuromuscular

ANDREW F. J. ABERCROMBY; WILLIAM E. AMONETTE; CHARLES S. LAYNE; BRIAN K. MCFARLIN; MARTHA R. HINMAN; WILLIAM H. PALOSKI

2007-01-01

82

Structure response and damage produced by ground vibration from surface mine blasting  

SciTech Connect

Direct measurements were made of ground-vibration-produced structure responses and damage in 76 homes for 219 production blasts. These results were combined with damage data from nine other blasting studies, including the three analyzed previously for Bureau of Mines Bulletin 656. Safe levels of ground vibration from blasting range from 0.5 to 2.0 in/sec peak particle velocity for residential-type structures. The damage threshold values are functions of the frequencies of the vibration transmitted into the residences and the types of construction. Particularly serious are the low-frequency vibrations that exist in soft foundation materials and/or result from long blast-to-residence distances. These vibrations produce not only structure resonances but also excessive levels of displacement and strain. Threshold damage was defined as the occurrence of cosmetic damage; that is, the most superficial interior cracking of the type that develops in all homes independent of blasting. Homes with plastered interior walls are more susceptible to blast-produced cracking than gypsum wallboard. Structure response amplification factors were measured. Typical values were 1.5 for structures as a whole (racking) and 4 for midwalls, at their respective resonance frequencies. For blast vibrations above 40 Hz, all amplification factors for frame residential structures were less than unity. The human response and annoyance problem from ground vibration is aggravated by wall rattling, secondary noises, and the presence of airblast. Approximately 5 to 10% of the neighbors will judge peak particle velocity levels of 0.5 to 0.75 in/sec as less than acceptable (i.e., unacceptable) based on direct reactions to the vibration. Even lower levels cause psychological response problems, and thus social, economic, and public relations factors become critical for continued blasting.

Siskind, D.E.; Stagg, M.S.; Kopp, J.W.; Dowding, C.H.

1980-01-01

83

Responses to Achilles tendon vibration during self-paced, visually and auditory-guided periodic sway  

Microsoft Academic Search

Achilles tendon vibration (ATV) alters proprioceptive input of the triceps surae muscles resulting in a posterior postural\\u000a shift during standing. When this is applied in combination with a more dynamic proprioceptive perturbation, postural responses\\u000a to ATV are attenuated. In this study, we applied ATV during self-paced, visually and auditory guided voluntary periodic sway\\u000a in order to examine how the vibration-induced

Saritha M. Radhakrishnan; Vassilia Hatzitaki; Dimitrios Patikas; Ioannis G. Amiridis

84

Intelligent control for braking-induced longitudinal vibration responses of floating-type railway bridges  

Microsoft Academic Search

This paper presents an intelligent control method and its engineering application in the control of braking-induced longitudinal vibration of floating-type railway bridges. Equations of motion for the controlled floating-type railway bridges have been established based on the analysis of the longitudinal vibration responses of floating-type railway bridges to train braking and axle-loads of moving trains. For engineering applications of the

Wei-Lian Qu; Shun-Quan Qin; Jian-Weia Tu; Jia Liu; Qiang Zhou; Haibin Cheng; Yong-Lin Pi

2009-01-01

85

The use of statistical characteristics of reducer vibrations as diagnostic symptoms  

NASA Technical Reports Server (NTRS)

The results of a statistical analysis of the vibrations of the experimental RS-1 reducer stand, with a spiral-gear transmission, operating on a closed circuit, are presented. The analysis was carried out on the Minsk-2 and Minsk-32 digital computers, with two-channel analog-digital converter, built in the Institute of the Science of Mechanics. Two-dimensional distribution patterns, conditional dispersions and dispersion ratios were calculated. The octave-band-filtered first harmonics of the tooth frequency f sub z of the vibrations at two different measurement points were considered as the components of the vibration process to be analyzed. The regression lines, corresponding to different values of the loading torque, are presented. Since it was not the gear drive parameters which were determined by diagnostic methods, but the characteristics most sensitive to change in state of the object of the investigation, the loading torque, which is the simplest and most accessible for measurement, was chosen as the condition parameter.

Balitskiy, F. Y.; Genkin, M. D.; Ivanova, M. A.; Sokolova, A. G.

1973-01-01

86

Evaluation of human response to structural vibration induced by sonic boom  

NASA Technical Reports Server (NTRS)

This paper addresses the topic of building vibration response to sonic boom and the evaluation of the associated human response to this vibration. The paper reexamines some of the issues addressed in the previous extensive coverage of the topic, primarily by NASA, and attempts to offer a fresh viewpoint for some of the problems that may assist in reassessing the potential impact of sonic boom over populated areas. The topics addressed are: (1) human response to vibration; (2) criteria for, and acoustic signature of rattle; (3) structural response to shaped booms, including definition of two new descriptors for assessing the structural response to sonic boom; and (4) a detailed review of the previous NASA/FAA Sonic Boom Test Program involving structural response measurements at Edwards AFB and an initial estimate of structural response to sonic booms from possible high speed civil transport configurations. Finally, these estimated vibration responses are shown to be substantially greater than the human response and rattle criteria developed earlier.

Sutherland, L. C.; Czech, J.

1992-01-01

87

Lunar seismic profiling experiment. [Apollo 17 flight measurements of lunar surface vibrations to determine subsurface characteristics  

NASA Technical Reports Server (NTRS)

The Apollo 17 lunar seismic profiling experiment was conducted to record the vibrations of the lunar surface as induced by explosive charges, the thrust of the lunar module ascent engine, and the crash of the lunar module ascent stage. Analysis of the data obtained made it possible to determine the internal characteristics of the lunar crust to a depth of several kilometers. The test equipment used in the experiment is described. Maps showing the location of the geophones and the deployed explosive packages are provided. Samples of the seismic signals recorded by the lunar seismic profiling experiment geophones are included.

Kovach, R. L.; Watkins, J. S.; Talwani, P.

1973-01-01

88

Measurements of an ARS DE204S Cryocooler's Thermal and Vibration Characteristics  

SciTech Connect

This document describes measurements that characterize an Advanced Research Systems DE204S cryocooler system. The data is relevant to the thermal performance and vibration characteristics of the cold-head. The thermal measurements include heat load mapping of the 1st and 2nd stage, and temperature fluctuation measurement of the 2nd stage heat station. A comparison of fluctuation measurements by four different sensors is also included to support the 2nd stage fluctuation results. Finally, optical measurement of the cyclic 2nd stage heat station deflection is described.

Haid, B

2004-08-24

89

Comparison between Deflection and Vibration Characteristics of Rectangular and Trapezoidal profile Microcantilevers  

PubMed Central

Arrays of microcantilevers are increasingly being used as physical, biological, and chemical sensors in various applications. To improve the sensitivity of microcantilever sensors, this study analyses and compares the deflection and vibration characteristics of rectangular and trapezoidal profile microcantilevers. Three models of each profile are investigated. The cantilevers are analyzed for maximum deflection, fundamental resonant frequency and maximum stress. The surface stress is modelled as in-plane tensile force applied on the top edge of the microcantilevers. A commercial finite element analysis software ANSYS is used to analyze the designs. Results show paddled trapezoidal profile microcantilevers have better sensitivity. PMID:22574041

Ansari, Mohd. Zahid; Cho, Chongdu; Kim, Jooyong; Bang, Booun

2009-01-01

90

Vibration characteristics of a large wind turbine tower on non-rigid foundations  

NASA Technical Reports Server (NTRS)

Vibration characteristics of the Mod-OA wind turbine supported by nonrigid foundations were investigated for a range of soil rigidities. The study shows that the influence of foundation rotation on the fundamental frequency of the wind turbine is quite significant for cohesive soils or loose sand. The reduction in natural frequency can be greater than 20 percent. However, for a foundation resting on well graded, dense granular materials or bedrock, such effect is small and the foundation can be treated as a fixed base.

Yee, S. T.; Cang, T. Y. P.; Scavuzzo, R. J.; Timmerman, D. H.; Fenton, J. W.

1977-01-01

91

Visual Stimulation Facilitates Penile Responses to Vibration in Men with and without Erectile Disorder.  

ERIC Educational Resources Information Center

Compared reflexogenic and psychogenic penile responses in men with and without erectile disorder. Hypothesized that men with psychogenic dysfunction respond minimally to vibrotactile stimulation. As predicted, responses were different in the vibration condition. Interpretations are provided in terms of attention and appraisal. (BF)

Janssen, Erick; And Others

1994-01-01

92

Subjective response to combined noise and vibration during flight of a large twin-jet airplane  

NASA Technical Reports Server (NTRS)

A NASA twin-jet airplane was used to obtain controlled noise and vibration environments during flight while obtaining subjective responses from 13 passenger-subjects (6 females and 7 males). Subjective ratings of overall comfort, comfort when considering only vibration, and comfort when considering only noise were obtained during times of different vibration and noise environments. Passenger-subjects were able to distinguish and rate noise better than vibration. In addition, there was a statistically significant difference in ratings of ride comfort due to both sex type and flight experience. Males rated flying discomfort much more severely than females when rating the overall ride and the ride when considering only the noise environment. Experienced passengers also rated the overall ride to be more uncomfortable than inexperienced passengers.

Clevenson, S. A.

1976-01-01

93

Draft American National Standard: Methods for measuring the vibration response of the ground.  

PubMed

Working Group 14 of the Acoustical Society of America/American National Standards Institute S2 Mechanical Vibration and Shock Committee (ASA/ANSI S2 WG14) was formed to develop a standard on methods for measuring the vibration response of the ground to be used when assessing potential impact upon vibration sensitive receivers in the vicinity of rail transit systems. The contents of the standard will be based upon industry accepted methods as described in the Federal Transit Administration guidance manual "Transit Noise and Vibration Impact Assessment" (FTA-VA-90-1003-06) while considering new developments since the latest version of the guidance manual was published in May 2006. This paper will describe the background of the methods and the structure, content, and status of the draft standard. PMID:25235562

Phillips, James E

2014-04-01

94

Vibration characteristics of aluminum surface subjected to ultrasonic waves and their effect on wetting behavior of solder droplets.  

PubMed

The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2s when the amplitude of the aluminum surface is higher than 5.4 ?m or when the amplitude of the liquid solder surface is higher than 10.2 ?m. PMID:24295911

Ma, Lin; Xu, Zhiwu; Zheng, Kun; Yan, Jiuchun; Yang, Shiqin

2014-03-01

95

Intelligent control for braking-induced longitudinal vibration responses of floating-type railway bridges  

NASA Astrophysics Data System (ADS)

This paper presents an intelligent control method and its engineering application in the control of braking-induced longitudinal vibration of floating-type railway bridges. Equations of motion for the controlled floating-type railway bridges have been established based on the analysis of the longitudinal vibration responses of floating-type railway bridges to train braking and axle-loads of moving trains. For engineering applications of the developed theory, a full-scale 500 kN smart magnetorheologic (MR) damper has been designed, fabricated and used to carry out experiments on the intelligent control of braking-induced longitudinal vibration. The procedure for using the developed intelligent method in conjunction with the full-scale 500 kN MR dampers has been proposed and used to control the longitudinal vibration responses of the deck of floating-type railway bridges induced by train braking and axle-loads of moving trains. This procedure has been applied to the longitudinal vibration control of the Tian Xingzhou highway and railway cable-stayed bridge over the Yangtze River in China. The simulated results have shown that the intelligent control system using the smart MR dampers can effectively control the longitudinal response of the floating-type railway bridge under excitations of braking and axle-loads of moving trains.

Qu, Wei-Lian; Qin, Shun-Quan; Tu, Jian-Weia; Liu, Jia; Zhou, Qiang; Cheng, Haibin; Pi, Yong-Lin

2009-12-01

96

Analysis of non-linear response of the human body to vertical whole-body vibration.  

PubMed

The human response to vibration is typically studied using linear estimators of the frequency response function, although different literature works evidenced the presence of non-linear effects in whole-body vibration response. This paper analyses the apparent mass of standing subjects using the conditioned response techniques in order to understand the causes of the non-linear behaviour. The conditioned apparent masses were derived considering models of increasing complexity. The multiple coherence function was used as a figure of merit for the comparison between the linear and the non-linear models. The apparent mass of eight male subjects was studied in six configurations (combinations of three vibration magnitudes and two postures). The contribution of the non-linear terms was negligible and was endorsed to the change of modal parameters during the test. Since the effect of the inter-subject variability was larger than that due to the increase in vibration magnitude, the biodynamic response should be more meaningfully modelled using a linear estimator with uncertainty rather than looking for a non-linear modelling. PMID:25105223

Tarabini, Marco; Solbiati, Stefano; Moschioni, Giovanni; Saggin, Bortolino; Scaccabarozzi, Diego

2014-11-01

97

Welding Characteristics of 67 kHz Ultrasonic Plastic Welding System Using Fundamental and Higher-Resonance-Frequency Vibrations  

NASA Astrophysics Data System (ADS)

The welding characteristics of a 67 kHz ultrasonic plastic welding system using fundamental and higher-resonance-frequency vibrations were studied and compared with those of the 27 kHz and 40 kHz systems. At high frequency, welding characteristics were improved due to the larger vibration loss of plastic materials. The 67 kHz welding tip vibrates at a maximum velocity of more than 2.3 m/s (peak-to-zero value) at a fundamental resonance frequency and there are several higher resonance frequencies up to 94 kHz whose vibration velocities are more than one-fourth that of the fundamental frequency. The welding characteristics of lapped 1.0-mm-thick polypropylene sheets were measured for the cases where the vibration system was driven using combined driving voltages of both fundamental and higher resonance frequencies. The welded area and weld strength increased when fundamental and higher resonance frequencies were driven simultaneously. The welding characteristics of the 67 kHz ultrasonic plastic welding system were improved significantly compared with those of 27 kHz and 40 kHz welding systems by driving fundamental and higher resonance frequencies simultaneously.

Hongoh, Misugi; Yoshikuni, Masafumi; Hashii, Hidekazu; Ueoka, Tetsugi; Tsujino, Jiromaru

2003-05-01

98

Welding Characteristics of 40 kHz Ultrasonic Plastic Welding System Using Fundamental and Higher-Resonance-Frequency Vibrations  

NASA Astrophysics Data System (ADS)

The welding characteristics of 40 kHz ultrasonic plastic welding system using fundamental and higher-resonance-frequency vibrations were studied. At high frequency, welding characteristics can be improved due to the larger vibration loss of plastic materials. The 40 kHz welding tip vibrates at a maximum velocity of more than 3.0 m/s (peak-to-zero value) at a fundamental resonance frequency and there are several higher resonance frequencies up to 107 kHz whose vibration velocities are more than one-fourth that of the fundamental frequency. The welding characteristics of lapped 0.5-mm-thick polyvinyl chloride and 1.0-mm-thick polypropylene sheets were measured in the cases where the vibration system was driven using combined driving voltages of both fundamental and higher resonance frequencies. The welded area and weld strength increased as fundamental and higher resonance frequencies were driven simultaneously. The welding characteristics of ultrasonic plastic welding were improved significantly by driving fundamental and higher resonance frequencies simultaneously.

Hongoh, Misugi; Iwase, Eri; Tsuboi, Hidenori; Ueoka, Tetsugi; Tsujino, Jiromaru

2002-05-01

99

A spider's biological vibration filter: Micromechanical characteristics of a biomaterial surface.  

PubMed

A strain-sensing lyriform organ (HS-10) found on all of the legs of a Central American wandering spider (Cupiennius salei) detects courtship, prey and predator vibrations transmitted by the plant on which it sits. It has been suggested that the viscoelastic properties of a cuticular pad directly adjacent to the sensory organ contribute to the organ's pronounced high-pass characteristics. Here, we investigate the micromechanical properties of the cuticular pad biomaterial in search of a deeper understanding of its impact on the function of the vibration sensor. These properties are considered to be an effective adaptation for the selective detection of signals for frequencies >40Hz. Using surface force spectroscopy mapping we determine the elastic modulus of the pad surface over a temperature range of 15-40°C at various loading frequencies. In the glassy state, the elastic modulus was ?100MPa, while in the rubbery state the elastic modulus decreased to 20MPa. These data are analyzed according to the principle of time-temperature superposition to construct a master curve that relates mechanical properties, temperature and stimulus frequencies. By estimating the loss and storage moduli vs. temperature and frequency it was possible to make a direct comparison with electrophysiology experiments, and it was found that the dissipation of energy occurs within a frequency window whose position is controlled by environmental temperatures. PMID:25065547

Young, Seth L; Chyasnavichyus, Marius; Erko, Maxim; Barth, Friedrich G; Fratzl, Peter; Zlotnikov, Igor; Politi, Yael; Tsukruk, Vladimir V

2014-11-01

100

Vibration and Structural Response of Hybrid Wind Turbine Blades  

E-print Network

mode, bending and twist, at the higher natural frequencies of the blade with tubular truss configuration. The weight saving measures in developing lighter blades in this study did not detract from the blades structural response for the selected load...

Nanami, Norimichi

2011-02-22

101

A computer toolbox for damage identification based on changes in vibration characteristics  

SciTech Connect

This paper introduces a new toolbox of graphical-interface software algorithms for the numerical simulation of vibration tests, analysis of modal data, finite element model correlation, and the comparison of both linear and nonlinear damage identification techniques. This toolbox is unique because it contains several different vibration-based damage identification algorithms, categorized as those which use only measured response and sensor location information ({open_quotes}non-model-based{close_quotes} techniques) and those which use finite element model correlation ({open_quotes}model-based{close_quotes} techniques). Another unique feature of this toolbox is the wide range of algorithms for experimental modal analysis. The toolbox also contains a unique capability that utilizes the measured coherence functions and Monte Carlo analysis to perform statistical uncertainty analysis on the modal correlation capabilities of toolbox, and also shows a sample application which uses the toolbox to analyze the statistical uncertainties on the results of a series of modal tests performed on a highway bridge.

Doebling, S.W.; Farrar, C.R. [Los Alamos National Lab., NM (United States); Cornwell, P.J. [Rose Hulman Institute of Technology, Terre Haute, IN (United States). Dept. of Mechanical Engineering

1997-09-01

102

Study of T53 engine vibration  

NASA Technical Reports Server (NTRS)

Vibration characteristics for overhauled T53 engines, including rejection rate, principal sources of vibration, and normal procedures taken by the overhaul center to reduce engine vibration are summarized. Analytical and experimental data were compared to determine the engine's dynamic response to unbalance forces with results showing that the engine operates through bending critical speeds. Present rigid rotor balancing techniques are incapable of compensating for the flexible rotor unbalance. A comparison of typical test cell and aircraft vibration levels disclosed significant differences in the engine's dynamic response. A probable spline shift phenomenon was uncovered and investigated. Action items to control costs and reduce vibration levels were identified from analytical and experimental studies.

Walter, T. J.

1978-01-01

103

Dynamic response of 1-in. form factor disk drives to external shock and vibration loads  

Microsoft Academic Search

The dynamic response of the head disk interface is investigated numerically for two different designs of 1-in. hard disk drive\\u000a enclosures, the so-called “thin” enclosure and the “thick” enclosure. First, the in-plane and out-of-plane vibration response\\u000a is determined. Then, the effects of linear shock and head slap are studied. Simulation results show that the thinner enclosure\\u000a has better performance with

Aravind N. Murthy; Mathias Pfabe; Jianfeng Xu; Frank E. Talke

2007-01-01

104

Experimental studies for determining human discomfort response to vertical sinusoidal vibration  

NASA Technical Reports Server (NTRS)

A study was conducted to investigate several problems related to methodology and design of experiments to obtain human comfort response to vertical sinusoidal vibration. Specifically, the studies were directed to the determination of (1) the adequacy of frequency averaging of vibration data to obtain discomfort predictors, (2) the effect of practice on subject ratings, (3) the effect of the demographic factors of age, sex, and weight, and (4) the relative importance of seat and floor vibrations in the determination of measurement and criteria specification location. Results indicate that accurate prediction of discomfort requires knowledge of both the acceleration level and frequency content of the vibration stimuli. More importantly, the prediction of discomfort was shown to be equally good based upon either floor accelerations or seat accelerations. Furthermore, it was demonstrated that the discomfort levels in different seats resulting from similar vibratory imputs were equal. Therefore, it was recommended that criteria specifications and acceleration measurements be made at the floor location. The results also indicated that practice did not systematically influence discomfort responses nor did the demographic factors of age, weight, and sex contribute to the discomfort response variation.

Dempsey, T. K.; Leatherwood, J. D.

1975-01-01

105

Exposure-response relationships for annoyance due to freight and passenger railway vibration exposure in residential environments.  

PubMed

In this work, exposure-response relationships for annoyance due to freight and passenger railway vibration exposure in residential environments are developed, so as to better understand the differences in human response to these two sources of environmental vibration. Data for this research come from a field study comprising interviews with respondents and measurements of their vibration exposure (N?=?752). A logistic regression model is able to accurately classify 96% of these measured railway vibration signals as freight or passenger based on two signal properties that quantify the duration and low frequency content of each signal. Exposure-response relationships are then determined using ordinal probit modeling with fixed thresholds. The results indicate that people are able to distinguish between freight and passenger railway vibration, and that the annoyance response due to freight railway vibration is significantly higher than that due to passenger railway vibration, even for equal levels of exposure. In terms of a community tolerance level, the population studied is 15?dB (re 10(-6) m?s(-2)) more tolerant to passenger railway vibration than freight railway vibration. These results have implications for the expansion of freight traffic on rail, or for policies to promote passenger railway. PMID:24437760

Sharp, Calum; Woodcock, James; Sica, Gennaro; Peris, Eulalia; Moorhouse, Andrew T; Waddington, David C

2014-01-01

106

Numerical determination of the transmissibility characteristics of a squeeze film damped forced vibration system  

NASA Technical Reports Server (NTRS)

Numerical solutions of the governing equations of motion of a liquid squeeze film damped forced vibration system were carried out to examine the feasibility of using a liquid squeeze film to cushion and protect large structures, such as buildings, located in areas of high seismic activity. The mathematical model used was that for a single degree of freedom squeeze film damped spring mass system. The input disturbance was simulated by curve fitting actual seismic data with an eleventh order Lagranging polynomial technique. Only the normal component of the seismic input was considered. The nonlinear, nonhomogeneous governing differential equation of motion was solved numerically to determine the transmissibility over a wide range of physical parameters using a fourth-order Runge-Kutta technique. It is determined that a liquid squeeze film used as a damping agent in a spring-mass system can significantly reduce the response amplitude for a seismic input disturbance.

Sutton, M. A.; Davis, P. K.

1976-01-01

107

Characteristics of blood flow resistance under transverse vibration: red blood cell suspension in Dextran-40.  

PubMed

Vibration under shear flow causes the reduction of flow resistance for shear-thinning fluids. The present study investigates the effect of vibration on the flow resistance of a nonaggregating red blood cell (RBC) suspension with a newly designed pressure-scanning capillary viscometer (PSCV). The PSCV was originally designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time, which was slightly modified and used for the present study. Low-frequency vibration was applied perpendicular to the direction of the flow. The effect of the transverse vibration was investigated for both Newtonian fluids and nonaggregating RBC suspensions. The experimental results showed that the vibration had no effect on the flow resistance of the Newtonian fluids. However, the vibration caused a reduction of the flow resistance of the RBC suspension. The reduction of the flow resistance was strongly dependent on both frequency and amplitude of vibration. PMID:14582610

Shin, Sehyun; Ku, Yunhee; Suh, Jang-Soo; Moon, Su-Yeon; Jang, Jong-Yun

2003-10-01

108

Analysis on problem of removing the odd point in rotors torsional vibration characteristics' calculation using Riccati method  

Microsoft Academic Search

Aiming at the problem of the odd point in the calculation of rotors torsional vibration characteristics by using the improved Riccati method, this paper presents a new viewpoint about how to confirm and remove the lost root and the accessional root.

Dan-Mei Xie; Juan Huang; Jian-Feng Wan; Ye Yuan

2003-01-01

109

Modulated pulses based distributed vibration sensing with high frequency response and spatial resolution.  

PubMed

A distributed optical fiber sensing system merged Mach-Zehnder interferometer and phase sensitive optical time domain reflectometer (?-OTDR) system for vibration measurement with high-frequency response and high spatial resolution is demonstrated, where modulated pulses are proposed to be used as sensing source. Frequency response and location information are obtained by Mach-Zehnder interferometer and ?-OTDR technology, respectively. In order to simulate high-frequency vibration of crack of cable and civil structure, experiments on detection of piezoelectric transducer and pencil-break are carried out. Spatial resolution of 5 m and the maximum frequency response of ~3 MHz are achieved in 1064 m fiber link when the narrow pulse width is 50 ns. PMID:23481753

Zhu, Tao; He, Qian; Xiao, Xianghui; Bao, Xiaoyi

2013-02-11

110

Free vibration characteristics of multiple load path blades by the transfer matrix method  

NASA Technical Reports Server (NTRS)

The determination of free vibrational characteristics is basic to any dynamic design, and these characteristics can form the basis for aeroelastic stability analyses. Conventional helicopter blades are typically idealized as single-load-path blades, and the transfer matrix method is well suited to analyze such blades. Several current helicopter dynamic programs employ transfer matrices to analyze the rotor blades. In this paper, however, the transfer matrix method is extended to treat multiple-load-path blades, without resorting to an equivalent single-load-path approximation. With such an extension, these current rotor dynamic programs which employ the transfer matrix method can be modified with relative ease to account for the multiple load paths. Unlike the conventional blades, the multiple-load-path blades require the introduction of the axial degree-of-freedom into the solution process to account for the differential axial displacements of the different load paths. The transfer matrix formulation is validated through comparison with the finite-element solutions.

Murthy, V. R.; Joshi, Arun M.

1986-01-01

111

Effects of adding whole body vibration to squat training on isometric force/time characteristics.  

PubMed

Resistance training interventions aimed at increasing lower-body power and rates of force development have produced varying results. Recent studies have suggested that whole-body low-frequency vibration (WBLFV) may elicit an acute postactivation potentiation response, leading to acute improvements in power and force development. Potentially, the use of WBLFV between sets of resistance training rather than during training itself may lead to increased recruitment and synchronization of high-threshold motor units, minimize fatigue potential, and facilitate the chronic adaptation to resistance exercise. The purpose of this study was to determine the effects of applying TriPlaner, WBLFV, prior to and then intermittently between sets of Smith machine squats on short-term adaptations in explosive isometric force expression. Thirty recreationally resistance trained men aged 18-30 were randomly assigned to 1 of 3 groups: resistance training only (SQT, n = 11), resistance plus whole-body vibration (SQTV, n = 13), or active control (CON, n = 6). An isometric squat test was performed prior to and following a 6-week periodized Smith machine squat program. Whole-body low-frequency vibration was applied 180 seconds prior to the first work set (50 Hz, 2-4 mm, 30 seconds) and intermittently (50 Hz, 4-6 mm, 3 x 10 seconds, 60 seconds between exposures) within a 240-second interset rest period. Subjects were instructed to assume a quarter squat posture while positioning their feet directly under their center of mass, which was modified using a handheld goniometer to a knee angle of 135 +/- 5 degrees . Instructions were given to subjects to apply force as fast and as hard as possible for 3.5 seconds. Isometric force (N) and rates of force development (N.s(-1)) were recorded from the onset of contraction (F(0)) to time points corresponding to 30, 50, 80, 100, 150, and 250 milliseconds, as well as the peak isometric rate of force development (PISORFD), and rate of force development to initial peak in force (RFDinitial). Repeated measures analysis of variance and analysis of covariance revealed no significant group by trial interactions for isometric rate of force development (ISORFD) between 0-30, 0-50, 0-80, 0-100, 0-150, and 0-250 milliseconds and PISORFD (p > 0.05). A significant group x trial interaction was seen for RFDinitial with SQTV >CG (p = 0.04, mean difference 997.2 N.s(-1)) and SQTV >SQT (p = 0.04, mean difference 1,994.22 N.s(-1)). Significant trial by covariate interactions (week one measures for ISORFD) and main effects for trial were observed for ISORFD between 0-80, 0-100, 0-and 150 milliseconds; PISORFD; and RFDinitial (p < 0.01). A significant trial effect was seen for Finitial (%) when expressed as a relative percentage of maximal voluntary contraction (MVC) (MVC = 100%) (p = 0.015; week 1 > week 7, mean difference, 5.82%). No significant differences were seen for any other force variables from the onset of contraction to MVC between weeks 1 and 7 (p > 0.05). The data suggest that there was a significant benefit afforded by adding WBLFV to a short-term resistance training protocol with regard to "explosive" strength expression. The addition of vibration prior to and between sets of resistance exercise may be a viable alternative to vibration applied during resistance exercise when trying to improve "explosive" isometric strength. PMID:19924007

Lamont, Hugh S; Cramer, Joel T; Bemben, Debra A; Shehab, Randa L; Anderson, Mark A; Bemben, Michael G

2010-01-01

112

Vibration response of a cracked rotor in presence of rotor stator rub  

NASA Astrophysics Data System (ADS)

Fatigue crack and rotor-stator rub are two important faults in rotating machinery. Researchers have mostly studied the vibration behavior of a rotor with crack and rotor-stator rub separately. However, once the crack is developed in a rotor, the rotor is more likely to make contact with stator under tight clearance conditions, due to increased vibration level. The present study is aimed to examine vibration response of the cracked rotor in presence of common rotor faults such as unbalance and rotor stator rub. Numerical and experimental investigations are carried out and steady-state vibration analysis is presented. Experimental investigation for a multifault rotor system is attempted for the first time. The full spectrum analysis has been used effectively to extract the distinctive directional features of these rotor faults. The investigation focuses on directional nature of the higher harmonics for identification of rub in the cracked rotor. The study reveals that spectrum rich in spectral lines is a rub symptom. However, these higher harmonics are weaker than the 1X response. Rub in uncracked rotor excites forward and backward whirling frequency components almost equally. Cracked rotor without rub exhibits strongly forward whirling vibrations. Rotor rub in the cracked rotor reveals different response compared with the uncracked rotor, particularly the nature of 2X and higher harmonics at corresponding subharmonic resonances. Backward whirling nature of 2X frequency component as well as that of higher harmonic (that matches with the bending natural frequency) at corresponding subharmonic resonances, has been proposed for diagnosis of rotor rub in cracked rotor.

Patel, Tejas H.; Darpe, Ashish K.

2008-11-01

113

Numerical study of characteristics of underground blast induced surface ground motion and their effect on above-ground structures. Part II. Effects on structural responses  

Microsoft Academic Search

Studies of structural responses and damage to high-frequency blast motion are very limited. Current practice uses some empirical allowable ground vibration limits in assessing structural performance. These empirical limits overlook the physical parameters that govern structural response and damage, such as the ground motion characteristics and inherent structural properties. This paper studies the response of RC frame structures to numerically

Hong Hao; Chengqing Wu

2005-01-01

114

Vibration Response Testing of the CEBAF 12GeV Upgrade Cryomodules  

SciTech Connect

The CEBAF 12 GeV upgrade project includes 80 new 7-cell cavities to form 10 cryomodules. These cryomodules were tested during production to characterize their microphonic response in situ. For several early cryomodules, detailed (vibration) modal studies of the cryomodule string were performed during the assembly process to identify the structural contributors to the measured cryomodule microphonic response. Structural modifications were then modelled, implemented, and verified by subsequent modal testing and in-situ microphonic response testing. Interim and latest results from this multi-stage process will be reviewed.

Davis, G. Kirk; Matalevich, Joseph R.; Wiseman, Mark A.; Powers, Thomas J.

2012-09-01

115

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

PubMed Central

To learn the differences between the structure-activity relationship and molecular vibration-activity relationship in the ligand-receptor interaction of the histamine receptor, 47 ligands of the histamine receptor were analyzed by structural similarity and molecular vibrational frequency patterns. The radial tree that was produced by clustering analysis of molecular vibrational frequency patterns shows its potential for the functional classification of histamine receptor ligands. PMID:23105941

2012-01-01

116

Stationary transducer response to planetary-gear vibration excitation II: Effects of torque modulations  

Microsoft Academic Search

The frequency spectra of the outputs of transducers fixed to the ring gears of planetary-gear systems contain useful information pertaining to the health of such systems. The effects on such frequency spectra arising from non-uniform loading carried by the M planets in such systems was derived and illustrated in “Stationary transducer response to planetary-gear vibration excitation with non-uniform planet loading,”

W. D. Mark

2009-01-01

117

Stationary transducer response to planetary-gear vibration excitation II: Effects of torque modulations  

Microsoft Academic Search

The frequency spectra of the outputs of transducers fixed to the ring gears of planetary-gear systems contain useful information pertaining to the health of such systems. The effects on such frequency spectra arising from non-uniform loading carried by the M planets in such systems was derived and illustrated in ``Stationary transducer response to planetary-gear vibration excitation with non-uniform planet loading,''

W. D. Mark

2009-01-01

118

Hormonal and Neuromuscular Responses to Mechanical Vibration Applied to Upper Extremity Muscles  

PubMed Central

Objective To investigate the acute residual hormonal and neuromuscular responses exhibited following a single session of mechanical vibration applied to the upper extremities among different acceleration loads. Methods Thirty male students were randomly assigned to a high vibration group (HVG), a low vibration group (LVG), or a control group (CG). A randomized double-blind, controlled-parallel study design was employed. The measurements and interventions were performed at the Laboratory of Biomechanics of the University of L'Aquila. The HVG and LVG participants were exposed to a series of 20 trials ×10 s of synchronous whole-body vibration (WBV) with a 10-s pause between each trial and a 4-min pause after the first 10 trials. The CG participants assumed an isometric push-up position without WBV. The outcome measures were growth hormone (GH), testosterone, maximal voluntary isometric contraction during bench-press, maximal voluntary isometric contraction during handgrip, and electromyography root-mean-square (EMGrms) muscle activity (pectoralis major [PM], triceps brachii [TB], anterior deltoid [DE], and flexor carpi radialis [FCR]). Results The GH increased significantly over time only in the HVG (P?=?0.003). Additionally, the testosterone levels changed significantly over time in the LVG (P?=?0.011) and the HVG (P?=?0.001). MVC during bench press decreased significantly in the LVG (P?=?0.001) and the HVG (P?=?0.002). In the HVG, the EMGrms decreased significantly in the TB (P?=?0.006) muscle. In the LVG, the EMGrms decreased significantly in the DE (P?=?0.009) and FCR (P?=?0.006) muscles. Conclusion Synchronous WBV acutely increased GH and testosterone serum concentrations and decreased the MVC and their respective maximal EMGrms activities, which indicated a possible central fatigue effect. Interestingly, only the GH response was dependent on the acceleration with respect to the subjects' responsiveness. PMID:25368995

Di Giminiani, Riccardo; Fabiani, Leila; Baldini, Giuliano; Cardelli, Giovanni; Giovannelli, Aldo; Tihanyi, Jozsef

2014-01-01

119

A forced response analysis and application of impact dampers to rotordynamic vibration suppression in a cryogenic environment  

E-print Network

A FORCED RESPONSE ANALYSIS AND APPLICATION OF IMPACT DAMPERS TO ROTORDYNAMIC VIBRATION SUPPRESSION IN A CRYOGENIC ENVIRONMENT A Thesis by JAMES JEFFREY MOORE Submitted to the Office of Graduate Studies of Texas ARM University in partial... fulfillment of the requirements for the degree of MASTER OF SCIENCE May 1993 Major Subject: Mechanical Engineering A FORCED RESPONSE ANALYSIS AND APPLICATION OF IMPACT DAMPERS TO ROTORDYNAMIC VIBRATION SUPPRESSION IN A CRYOGENIC ENVIRONMENT A Thesis...

Moore, James Jeffrey

2012-06-07

120

Parametric identification of a time-varying structure based on vector vibration response measurements  

NASA Astrophysics Data System (ADS)

The problem of parametric output-only identification of a time-varying structure based on vector random vibration signal measurements is considered. A functional series vector time-dependent autoregressive moving average (FS-VTARMA) method is introduced and employed for the identification of a "bridge-like" laboratory structure consisting of a beam and a moving mass. The identification is based on three simultaneously measured vibration response signals obtained during a single experiment. The method is judged against baseline modelling based on multiple "frozen-configuration" stationary experiments, and is shown to be effective and capable of accurately tracking the dynamics. Additional comparisons with a recursive pseudo-linear regression VTARMA (PLR-VTARMA) method and a short time canonical variate analysis (ST-CVA) subspace method are made and demonstrate the method's superior achievable accuracy and model parsimony.

Spiridonakos, M. D.; Fassois, S. D.

2009-08-01

121

Chaotic response is a generic feature of vortex-induced vibrations of flexible risers  

NASA Astrophysics Data System (ADS)

We show through analysis of experimental data that the vortex-induced vibrations of long flexible risers are characterized by time intervals of chaotic response, followed or preceded by periods of statistically stationary response. Regions of chaotic response have been ignored in past analyses, while they contain distinctly different response features and have significant implications on riser fatigue analysis. Whereas periods of statistically stationary response are characterized by nearly mono-frequency traveling waves, with small standing wave contributions, near the ends of the riser, and possibly accompanied by sharply peaked third and fifth force harmonics, the chaotic response is characterized by a rather wide-band spectrum with several individual peaks and a mix of traveling and standing waves. Phase-plane plots and Poincaré maps show typical features of chaotic response for the latter, while the statistically stationary response can be classified as periodic or quasi-periodic. Focusing on the Strouhal region of the response spectrum gives adequate results for the statistically stationary response, provided the higher force harmonics are also accounted for, but is inadequate for the chaotic parts of the response, whose fatigue properties are influenced by the entire broader-band spectrum. It is remarkable that both sheared and uniform current profiles cause both quasi-periodic and chaotic responses.

Modarres-Sadeghi, Y.; Chasparis, F.; Triantafyllou, M. S.; Tognarelli, M.; Beynet, P.

2011-05-01

122

Analyses of contact forces and vibration response for a defective rolling element bearing using an explicit dynamics finite element model  

NASA Astrophysics Data System (ADS)

This paper provides insights into the physical mechanism by which defect-related impulsive forces, and consequently, vibrations are generated in defective rolling element bearings. A dynamic nonlinear finite element model of a rolling element bearing with an outer raceway defect was numerically solved using the explicit dynamics finite element software package, LS-DYNA. A hypothesis was developed to explain the numerical noise observed in the predicted vibrations and contact forces, and the noise frequencies were analytically estimated. In-depth analyses of the numerically estimated dynamic contact forces between the rolling elements and the raceways of a bearing, which are not measured in practice, and have not been reported previously, are presented in this paper. Several events associated with the traverse of the rolling elements through the outer raceway defect are elaborated, and the impulsive force generating mechanism is explained. It was found that the re-stressing of the rolling elements that occurs near the end of a raceway defect generates a burst of multiple short-duration force impulses. The modelling results also highlight that much higher contact forces and accelerations are generated on the exit of the rolling elements out of defect compared to when they strike the defective surface. A bearing with a machined outer raceway defect was tested in a controlled experiment; the measured acceleration response compared favourably with the numerically modelled acceleration results, thereby, validating the low- and high-frequency characteristics of the de-stressing and re-stressing of the rolling elements, respectively.

Singh, Sarabjeet; Köpke, Uwe G.; Howard, Carl Q.; Petersen, Dick

2014-10-01

123

Experimental study of amplitude-phase-frequency characteristics of flow when following over a vibrating plate  

NASA Astrophysics Data System (ADS)

Consideration is given to the technique and results of preliminary experimental study on nonstationary hydrodynamics of flow when flowing over a vibrating plate located along a rectangular channel axis. In the experiment the use was made of plate with artificial roughness in the form of ribs formed by spiral wire windings. The amplitude of flow velocity oscillation was found to grow as the plate vibration frequency increased. An occurrence of diverse phase displacements between plate displacement and flow velocity oscillations is demonstrated.

Fedotovskij, V. S.; Terenik, L. V.; Spirov, V. S.

124

Characteristics of Blood Flow Resistance Under Transverse Vibration: Red Blood Cell Suspension in Dextran40  

Microsoft Academic Search

Vibration under shear flow causes the reduction of flow resistance for shear-thinning fluids. The present study investigates the effect of vibration on the flow resistance of a nonaggregating red blood cell (RBC) suspension with a newly designed pressure-scanning capillary viscometer (PSCV). The PSCV was originally designed to measure non-Newtonian viscosity continuously over a range of shear rates at a time,

Sehyun Shin; Yunhee Ku; Jang-Soo Suh; Su-Yeon Moon; Jong-Yun Jang

2003-01-01

125

Experimental study on seismic responses of piping systems with friction. Part 1: Large-scale shaking table vibration test  

SciTech Connect

This report deals with the experimental study of seismic response behavior of piping systems in industrial facilities such as petrochemical, oil refinery, and nuclear plants. Special attention is focused on the nonlinear dynamic response of piping systems due to frictional vibration appearing in piping and supporting devices. A three-dimensional mock-up piping and supporting structure model wherein piping is of 30-m length and 200-mm diameter is excited by a large-scale (15 m x 15 m) shaking table belong to the National Research Institute for Earth Science and Disaster Prevention in Tsukuba, Ibaraki. Power spectra of the response vibration and the loading-response relationship in the form of a hysteresis loop under several loading conditions are obtained. The response reduction effect caused by frictional vibration is evaluated and demonstrated in terms of response reduction factor.

Suzuki, K.; Watanabe, T.; Mitsumori, T. [Tokyo Metropolitan Univ. (Japan). Dept. of Mechanical Engineering; Shimizu, N. [Iwaki Meisei Univ., Iwaki, Fukushima (Japan). Dept. of Mechanical Engineering; Kobayashi, H. [Ishikawajima-Harima Heavy Industries Co., Ltd., Yokohama (Japan). Nuclear Power Div.; Ogawa, N. [National Research Inst. for Earth Science and Disaster Prevention, Tsukuba, Ibaraki (Japan)

1995-08-01

126

Tendon vibration attenuates superficial venous vessel response of the resting limb during static arm exercise  

PubMed Central

Background The superficial vein of the resting limb constricts sympathetically during exercise. Central command is the one of the neural mechanisms that controls the cardiovascular response to exercise. However, it is not clear whether central command contributes to venous vessel response during exercise. Tendon vibration during static elbow flexion causes primary muscle spindle afferents, such that a lower central command is required to achieve a given force without altering muscle force. The purpose of this study was therefore to investigate whether a reduction in central command during static exercise with tendon vibration influences the superficial venous vessel response in the resting limb. Methods Eleven subjects performed static elbow flexion at 35% of maximal voluntary contraction with (EX + VIB) and without (EX) vibration of the biceps brachii tendon. The heart rate, mean arterial pressure, and rating of perceived exertion (RPE) in overall and exercising muscle were measured. The cross-sectional area (CSAvein) and blood velocity of the basilic vein in the resting upper arm were assessed by ultrasound, and blood flow (BFvein) was calculated using both variables. Results Muscle tension during exercise was similar between EX and EX + VIB. However, RPEs at EX + VIB were lower than those at EX (P <0.05). Increases in heart rate and mean arterial pressure during exercise at EX + VIB were also lower than those at EX (P <0.05). CSAvein in the resting limb at EX decreased during exercise from baseline (P <0.05), but CSAvein at EX + VIB did not change during exercise. CSAvein during exercise at EX was smaller than that at EX + VIB (P <0.05). However, BFvein did not change during the protocol under either condition. The decreases in circulatory response and RPEs during EX + VIB, despite identical muscle tension, showed that activation of central command was less during EX + VIB than during EX. Abolishment of the decrease in CSAvein during exercise at EX + VIB may thus have been caused by a lower level of central command at EX + VIB rather than EX. Conclusion Diminished central command induced by tendon vibration may attenuate the superficial venous vessel response of the resting limb during sustained static arm exercise. PMID:23134654

2012-01-01

127

Response characteristics of the human torsional vestibuloocular reflex  

NASA Technical Reports Server (NTRS)

The characteristics of the response dynamics of the human torsional vestibuloocular reflex were studied during controlled rotations about an earth-horizontal axis. The results extended the frequency range to 2 Hz and identified the nonlinearity of the amplitude response.

Peterka, Robert J.

1992-01-01

128

Assessment of Regional Ventilation Distribution: Comparison of Vibration Response Imaging (VRI) with Electrical Impedance Tomography (EIT)  

PubMed Central

Background Vibration response imaging (VRI) is a bedside technology to monitor ventilation by detecting lung sound vibrations. It is currently unknown whether VRI is able to accurately monitor the local distribution of ventilation within the lungs. We therefore compared VRI to electrical impedance tomography (EIT), an established technique used for the assessment of regional ventilation. Methodology/Principal Findings Simultaneous EIT and VRI measurements were performed in the healthy and injured lungs (ALI; induced by saline lavage) at different PEEP levels (0, 5, 10, 15 mbar) in nine piglets. Vibration energy amplitude (VEA) by VRI, and amplitudes of relative impedance changes (rel.?Z) by EIT, were evaluated in seven regions of interest (ROIs). To assess the distribution of tidal volume (VT) by VRI and EIT, absolute values were normalized to the VT obtained by simultaneous spirometry measurements. Redistribution of ventilation by ALI and PEEP was detected by VRI and EIT. The linear correlation between pooled VT by VEA and rel.?Z was R2?=?0.96. Bland-Altman analysis showed a bias of ?1.07±24.71 ml and limits of agreement of ?49.05 to +47.36 ml. Within the different ROIs, correlations of VT-distribution by EIT and VRI ranged between R2 values of 0.29 and 0.96. ALI and PEEP did not alter the agreement of VT between VRI and EIT. Conclusions/Significance Measurements of regional ventilation distribution by VRI are comparable to those obtained by EIT. PMID:24475160

Bentley, Alexander H.; Hartmann, Erik K.; Klein, Klaus U.; Bodenstein, Marc; Baumgardner, James E.; David, Matthias; Ullrich, Roman; Markstaller, Klaus

2014-01-01

129

Test-Anchored Vibration Response Predictions for an Acoustically Energized Curved Orthogrid Panel with Mounted Components  

NASA Technical Reports Server (NTRS)

A rich body of vibroacoustic test data was recently generated at Marshall Space Flight Center for a curved orthogrid panel typical of launch vehicle skin structures. Several test article configurations were produced by adding component equipment of differing weights to the flight-like vehicle panel. The test data were used to anchor computational predictions of a variety of spatially distributed responses including acceleration, strain and component interface force. Transfer functions relating the responses to the input pressure field were generated from finite element based modal solutions and test-derived damping estimates. A diffuse acoustic field model was employed to describe the assumed correlation of phased input sound pressures across the energized panel. This application demonstrates the ability to quickly and accurately predict a variety of responses to acoustically energized skin panels with mounted components. Favorable comparisons between the measured and predicted responses were established. The validated models were used to examine vibration response sensitivities to relevant modeling parameters such as pressure patch density, mesh density, weight of the mounted component and model form. Convergence metrics include spectral densities and cumulative root-mean squared (RMS) functions for acceleration, velocity, displacement, strain and interface force. Minimum frequencies for response convergence were established as well as recommendations for modeling techniques, particularly in the early stages of a component design when accurate structural vibration requirements are needed relatively quickly. The results were compared with long-established guidelines for modeling accuracy of component-loaded panels. A theoretical basis for the Response/Pressure Transfer Function (RPTF) approach provides insight into trends observed in the response predictions and confirmed in the test data. The software modules developed for the RPTF method can be easily adapted for quick replacement of the diffuse acoustic field with other pressure field models; for example a turbulent boundary layer (TBL) model suitable for vehicle ascent. Wind tunnel tests have been proposed to anchor the predictions and provide new insight into modeling approaches for this type of environment. Finally, component vibration environments for design were developed from the measured and predicted responses and compared with those derived from traditional techniques such as Barrett scaling methods for unloaded and component-loaded panels.

Frady, Gregory P.; Duvall, Lowery D.; Fulcher, Clay W. G.; Laverde, Bruce T.; Hunt, Ronald A.

2011-01-01

130

Temporal response of biological cells to high-frequency optical jumping and vibrating tweezers  

NASA Astrophysics Data System (ADS)

We analyzed the temporal responses of biological cells in the jumping and vibrating optical tweezers for tugging, wiggling and stretching the cells with the finite element method. Some new concepts were established, which might be investigated in the future experiments, such as the jumping of local stress and local strain, independently on the recovery time of the viscoelastic material and on the jumping frequency, the energy dissipation in the hysteresis cycles, the cytoplasm fluid field and its interaction with the cell membrane. The cell was modeled with full 3D structure and viscoelastic continuum materials.

Yu, Lingyao; Sheng, Yunlong

2014-09-01

131

Myoelectric Response of Back Muscles to Vertical Random Whole-Body Vibration with Different Magnitudes at Different Postures  

NASA Astrophysics Data System (ADS)

Back muscle forces contribute essentially to the whole-body vibration-induced spinal load. The electromyogram (EMG) can help to estimate these forces during whole-body vibration (WBV). Thirty-eight subjects were exposed to identical random low-frequency WBV (0·7, 1·0 and 1·4 m/s-2 r.m.s. weighted acceleration) at a relaxed, erect and bent forward postures. The acceleration of the seat and the force between the seat and the buttocks were measured. Six EMGs were derived from the right side of the m. trapezius pars descendens, m. ileocostalis lumborum pars thoracis, m. ileocostalis lumborum pars lumborum; m. longissimus thoracis pars thoracis, m. longissimus thoracis pars lumborum, and lumbar multifidus muscle. All data were filtered for anti-aliasing and sampled with 1000 Hz. Artefacts caused by the ECG in the EMG were identified and eliminated in the time domain using wavelets. The individually rectified and normalized EMGs were averaged across subjects. The EMGs without WBV exhibited characteristic patterns for the three postures examined. The coherence and transfer functions indicated characteristic myoelectric responses to random WBV with several effects of posture and WBV magnitude. A comprehensive set of transfer functions from the seat acceleration or the mean normalized input force to the mean processed EMG was presented.The results can be used for the development of more sophisticated models with a separate control of various back muscle groups. However, the EMG-force relationship under dynamic conditions needs to be examined in more detail before the results can be implemented. Since different reflex mechanisms depending on the frequency of WBV are linked with different types of active muscle fibres, various time delays between the EMG and muscle force may be necessary.

BLÜTHNER, R.; SEIDEL, H.; HINZ, B.

2002-05-01

132

Distributed vibration/acoustic sensing with high frequency response and spatial resolution based on time-division multiplexing  

NASA Astrophysics Data System (ADS)

A novel time-division multiplexing scheme is proposed and demonstrated for distributed vibration/acoustic sensing with broad frequency response range and high spatial resolution. By setting the time delay between a narrow pulse and a quasi-continuous wave properly, conventional phase optical time-domain reflectometry and polarization diversity scheme can be combined without crosstalk to determine position and frequency of vibration event, respectively. Detections of high vibration frequency of 0.6 MHz and low frequency of 1 Hz are presented with 1 m spatial resolution over 680 m single-mode sensing fiber.

Qin, Zengguang; Chen, Liang; Bao, Xiaoyi

2014-11-01

133

Solar Ultraviolet Magnetograph Investigation (SUMI) Component Responses to Payload Vibration Testing  

NASA Technical Reports Server (NTRS)

Vibration testing of SUMI was performed at both the experiment and payload levels. No accelerometers were installed inside the experiment during testing, but it is certain that component responses were very high. The environments experienced by optical and electronic components in these tests is an area of ongoing concern. The analysis supporting this presentation included a detailed finite element model of the SUMI experiment section, the dynamic response of which, correlated well with accelerometer measurements from the testing of the experimental section at Marshall Space Flight Center. The relatively short timeframe available to complete the task and the limited design information available was a limitation on the level of detail possible for the non-experiment portion of the model. However, since the locations of interest are buried in the experimental section of the model, the calculated responses should be enlightening both for the development of test criteria and for guidance in design.

Hunt, Ronald A.

2011-01-01

134

[The evaluation of the working conditions and the characteristics of the prevalence of vibration-induced disease among miners in the Far North].  

PubMed

The article covers the data of physiologic and hygienic evaluation of vibration disease prevalence among miners of Far North and evaluation of their work conditions. The authors compare effects of local vibration on miners in the mines with negative ambient temperatures during the year and in those with the low positive temperatures. The negative temperatures and local vibration appeared to disorder formation of specific physiologic response to the stated factors. The data presented cover prevalence and progressing of vibration disease among the miners in Far North. PMID:7834225

Suvorov, G A; Rukavishnikov, V S; Pankov, V A

1994-01-01

135

On the correlation of output rate and aerodynamic characteristics in vibrating-mesh-based aqueous aerosol delivery.  

PubMed

Aerosolization of aqueous formulations is of special interest for inhalative drug delivery, where an adequate nebulizer performance represents a prerequisite for improving pulmonary therapy. The present study investigated the interplay of output rate and aerodynamic characteristics of different excipient-based formulations and its impact on the atomization process by vibrating-mesh technology (i.e. eFlow(®)rapid). Output rate and aerodynamic characteristics were manipulated by both dynamic viscosity and conductivity of the applied formulation. Supplementation with sucrose and sodium chloride caused a decline (down to ?0.2 g/min) and elevation (up to ?1.0 g/min) of the nebulizer output rate, respectively. However, both excipients were capable of decreasing the aerodynamic diameter of produced aerosol droplets from >7.0 ?m to values of ?5.0 ?m. Thus, the correlation of output rate and aerodynamic characteristics resulted in linear fits of opposite slopes (R(2)>0.85). Finally, the overall number of delivered aerosol droplets per time was almost constant for sucrose (?1×10(8) droplets/s), while for sodium chloride a concentration-dependent increase was observed (up to ?3×10(8) droplets/s). Overall, the current findings illustrated the influence of formulation parameters on the aerosolization process performed by vibrating-mesh technology. Moreover, concentration and charge distribution of aerosol populations supposedly modify the final characteristics of the delivered aerosols. PMID:24291081

Beck-Broichsitter, Moritz; Oesterheld, Nina; Knuedeler, Marie-Christine; Seeger, Werner; Schmehl, Thomas

2014-01-30

136

Test-Anchored Vibration Response Predictions for an Acoustically Energized Curved Orthogrid Panel with Mounted Components  

NASA Technical Reports Server (NTRS)

rich body of vibroacoustic test data was recently generated at Marshall Space Flight Center for component-loaded curved orthogrid panels typical of launch vehicle skin structures. The test data were used to anchor computational predictions of a variety of spatially distributed responses including acceleration, strain and component interface force. Transfer functions relating the responses to the input pressure field were generated from finite element based modal solutions and test-derived damping estimates. A diffuse acoustic field model was applied to correlate the measured input sound pressures across the energized panel. This application quantifies the ability to quickly and accurately predict a variety of responses to acoustically energized skin panels with mounted components. Favorable comparisons between the measured and predicted responses were established. The validated models were used to examine vibration response sensitivities to relevant modeling parameters such as pressure patch density, mesh density, weight of the mounted component and model form. Convergence metrics include spectral densities and cumulative root-mean squared (RMS) functions for acceleration, velocity, displacement, strain and interface force. Minimum frequencies for response convergence were established as well as recommendations for modeling techniques, particularly in the early stages of a component design when accurate structural vibration requirements are needed relatively quickly. The results were compared with long-established guidelines for modeling accuracy of component-loaded panels. A theoretical basis for the Response/Pressure Transfer Function (RPTF) approach provides insight into trends observed in the response predictions and confirmed in the test data. The software developed for the RPTF method allows easy replacement of the diffuse acoustic field with other pressure fields such as a turbulent boundary layer (TBL) model suitable for vehicle ascent. Structural responses using a TBL model were demonstrated, and wind tunnel tests have been proposed to anchor the predictions and provide new insight into modeling approaches for this environment. Finally, design load factors were developed from the measured and predicted responses and compared with those derived from traditional techniques such as historical Mass Acceleration Curves and Barrett scaling methods for acreage and component-loaded panels.

Frady, Gregory P.; Duvall, Lowery D.; Fulcher, Clay W. G.; Laverde, Bruce T.; Hunt, Ronald A.

2011-01-01

137

Vibration damping characteristics of a thin cylindrical shell stiffened with viscoelastic rings  

Microsoft Academic Search

The vibrations of a circular cylindrical shell reinforced with viscoelastic rings are theoretically treated. The frequency equation is derived using the transfer matrix together with the stiffness matrix. The numerical example surveys the damping effect of viscoelastic rings upon the dynamic behavior of the system.

H. Saito; H. Yamaguchi

1979-01-01

138

Response characteristics of luminescent oxygen sensors  

Microsoft Academic Search

Nonlinea Stern-Volmer quenching characteristics are a common feature of oxygen sensors containing Ru(II) complexes immobilized in solid-state matrices. We discuss the origins of this behaviour and address the implications of the molecular processes on sensor performance with the help of two different sensor systems: (1) For tris(2,2?-bipyridyl)Ru(II) dichloride (Rubpy) adsorbed on silica-gel the influence of both the absorption isotherm and

Paul Hartmann; Marc J. P. Leiner; Max E. Lippitsch

1995-01-01

139

Damping characteristics and flow behaviors of an ER fluid with a piston sine vibration in a viscous damper  

NASA Astrophysics Data System (ADS)

The damping characteristics and flow behaviors of ER fluids inside a piston-cylinder viscous damper subjected to external electric fields are studied based on experiment, theoretical analysis and numerical simulation. The viscous damper is a closed system with an inner piston and an outer cylinder, which is designed and constructed in our laboratory. In the experiment, the test ER fluid is enclosed in the gap of a piston-cylinder system. To examine the damping characteristics of the test ER fluid, a piston sine vibration experiment is performed with accompanying theoretical analyses. In addition, in order to investigate the ER flow behaviors inside the damper, a numerical simulation is carried out. The present study discloses the damping characteristics and the fluid mechanism of the ER fluid in the piston-cylinder damper with an applied external electric field.

Yamaguchi, Hiroshi; Zhang, Xin-Rong; Niu, Xiao-Dong

2010-10-01

140

Resonant properties of a nonlinear dissipative layer excited by a vibrating boundary: Q-factor and frequency response.  

PubMed

Simplified nonlinear evolution equations describing non-steady-state forced vibrations in an acoustic resonator having one closed end and the other end periodically oscillating are derived. An approach based on a nonlinear functional equation is used. The nonlinear Q-factor and the nonlinear frequency response of the resonator are calculated for steady-state oscillations of both inviscid and dissipative media. The general expression for the mean intensity of the acoustic wave in terms of the characteristic value of a Mathieu function is derived. The process of development of a standing wave is described analytically on the base of exact nonlinear solutions for different laws of periodic motion of the wall. For harmonic excitation the wave profiles are described by Mathieu functions, and their mean energy characteristics by the corresponding eigenvalues. The sawtooth-shaped motion of the boundary leads to a similar process of evolution of the profile, but the solution has a very simple form. Some possibilities to enhance the Q-factor of a nonlinear system by suppression of nonlinear energy losses are discussed. PMID:15759681

Enflo, B O; Hedberg, C M; Rudenko, O V

2005-02-01

141

Flow-induced vibration of component cooling water heat exchangers  

Microsoft Academic Search

This paper presents an evaluation of flow-induced vibration problems of component cooling water heat exchangers in one of Taipower's nuclear power stations. Specifically, it describes flow-induced vibration phenomena, tests to identify the excitation mechanisms, measurement of response characteristics, analyses to predict tube response and wear, various design alterations, and modifications of the original design. Several unique features associated with the

Y. S. Yeh; S. S. Chen

1990-01-01

142

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

PubMed

The conformational and IR and Raman spectral studies of 2-(2-hydroxyphenyl)benzothiazole have been carried out by using the DFT method at the B3LYP/6-311++G(**) level. The detailed vibrational assignments have been done on the basis of calculated potential energy distributions. Comparative studies of molecular geometries, atomic charges and vibrational fundamentals of all the conformers have been made. There are four possible conformers for this molecule. The optimized geometrical parameters obtained by B3LYP/6-311++G(**) method showed good agreement with the experimental X-ray data. The atomic polar tensor (APT) charges, Mulliken atomic charges, natural bond orbital (NBO) analysis and HOMO-LUMO energy gap of HBT and its conformers were also computed. PMID:24727164

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

2014-08-14

143

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

144

Characteristics of shock wave propagation in a vibrationally inhomogeneous gas under nonuniform excitation  

Microsoft Academic Search

The objective of the study was to analyze the influence of hydrodynamic effects, associated with nonuniform parameter distribution in a vibrationally excited gas, on the motion of a plane shock wave. The analysis is carried out for a CO2-N2 mixture, which is commonly used in gas-discharge lasers. The results obtained demonstrate the importance of including the hydrodynamic effects in the

A. Ia. Rudnitskii; A. M. Starik

1990-01-01

145

Characteristics of the Integrated Electromyogram in Individuals Exposed to Long-Term Vibration  

Microsoft Academic Search

The functional state of the forearm muscles in individuals exposed to long-term vibration (dressers with a duration of current employment of 7–15 years, n = 12) was assessed using turn–amplitude analysis of the integrated surface electromyogram (EMG), the nerve conduction velocity test, and the conventional motor unit action potential electromyographic test. A significant increase in the EMG amplitude and the

E. S. Antropova; L. I. Gerasimova; A. Yu. Meigal

2003-01-01

146

Vibration characteristics of micromachined piezoelectric diaphragms with a standing beam subjected to airflow  

Microsoft Academic Search

This paper presents a novel configuration consisting of a micromachined diaphragm and a standing beam for sensing airflow. A piezoelectric Pb(Zr,Ti)O3 (PZT) film is deposited by spin-coating on the diaphragm to actuate and sense the vibration at its resonant frequency. A standing and extruded beam built on the diaphragm responds to the aerodynamic drag force, inducing mechanical strain, increasing the

X. M. Jing; J. M. Miao; T. Xu; M. Olfatnia; L. Norford

2010-01-01

147

Static strain and vibration characteristics of a metal semimonocoque helicopter tail cone of moderate size  

NASA Technical Reports Server (NTRS)

The results are presented of an analytic and experimental research program involving a Sikorsky S-55 helicopter tail cone directed ultimately to the improved structural analysis of airframe substructures typical of moderate sized helicopters of metal semimonocoque construction. Experimental static strain and dynamic shake-testing measurements are presented. Correlation studies of each of these tests with a PC-based finite element analysis (COSMOS/M) are described. The tests included static loadings at the end of the tail cone supported in the cantilever configuration as well as vibrational shake-testing in both the cantilever and free-free configurations.

Bielawa, Richard L.; Hefner, Rachel E.; Castagna, Andre

1991-01-01

148

Analysis of lateral and torsional vibration characteristics of beams and shafts with end located rotational masses  

NASA Technical Reports Server (NTRS)

Partial differential equations are derived for free lateral and torsional vibration of a uniform free-free beam with a rotational mass attached to each extremity. For appropriate boundary conditions, nonlinear algebraic equations are obtained using a symbolic manipulation computer program, the solutions of which enable the computation of the neutral frequencies and mode-shapes. The mode-shapes are linear combinations of trigonometric and hyperbolic sine and cosine functions. A computer program is written for the numerical solution of the algebraic equations mentioned above, which can compute the natural frequencies, mode-shapes, and node points for any given set of parameters, for any given number of modes.

Robertson, D. K.

1984-01-01

149

Temperature Rise and Welding Characteristics of Ultrasonic Wire Bonding Using 190 kHz Linear, Circular and Square Vibration Loci and 600 kHz Linear Vibration Locus Welding Tips  

NASA Astrophysics Data System (ADS)

Welding characteristics of ultrasonic wire bonding using 190 kHz linear, circular and square vibration loci and a 600 kHz linear vibration locus are studied. High-frequency systems at 90 780 kHz have been shown to be significantly effective in comparison to a conventional system at 60 kHz. Aluminum wire welding specimens 0.1 mm in diameter have been successfully joined. Temperature increases at welding parts are measured from the thermoelectromotive force between the aluminum wire and copper plate specimens, and deformation at welded parts of wire specimens are measured using a digital height gage. Complex vibration welding tips at 190 kHz, which vibrate in elliptical to circular or rectangular to square shapes at either the same or different frequencies, are effective in joining welding specimens successfully in shorter welding times, under smaller vibration amplitudes and over wider good welding areas. A high-frequency 600 kHz system with a linear vibration locus is also effective for successful wire bonding. Both the temperature increase and wire deformation correlate well with the weld strength.

Tsujino, Jiromaru; Yoshihara, Hiroyuki; Itoh, Tomohiko; Inujima, Kazutoshi; Hirano, Yasuyuki

1998-05-01

150

Characteristic negative response of the helium ionization detector  

Microsoft Academic Search

When ultrapure helium is used as a carrier gas, the helium ionization detector provides a characteristic response, either positive or negative to each gas. The detector response can be made positive for all gases except neon by the inclusion of a few ppM of gaseous additives to the helium carrier gas, but the inclusion of gaseous additives decreases the detector

Fikry F. Andrawes; Everett K. Gibson

1980-01-01

151

Resonant response of a tapered beam and its implications to blade vibration  

SciTech Connect

The objective of the work reported here is to determine the effect of taper and tip thickness on the maximum resonant stress of a tapered beam subjected to externally applied harmonic pressure distributions and to investigate its possible implications to blade vibration. Tapered beams are of interest since their geometry is similar to that of the leading or trailing edge of an airfoil. As a result, airfoil chordwise bending modes should exhibit similar sensitivity to changes in chordwise taper and leading or tailing edge thickness. As a result, the tapered beam provides a simplified, first-order model of an airfoil`s behavior that should provide insight into the sensitivity of the airfoil`s response to geometric perturbations. The sensitivity of the response to geometric changes also depends on the type of excitation that is applied. The spatial distributions of the excitation pressures used in this study are: a constant pressure to serve as a baseline, a leading edge type pressure distribution, and a trailing edge type pressure distribution. Consequently, the relative importance of each type of excitation in terms of how it affects tip mode response will be assessed.

Balaji, G.N.; Griffin, J.H. [Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Mechanical Engineering

1997-01-01

152

Smart vibration control analysis of seismic response using MR dampers in the elevated highway bridge structures  

NASA Astrophysics Data System (ADS)

The magnetorheological (MR) damper is on of the smart controllers used widely in civil engineering structures. These kinds of dampers are applied in the paper in the elevated highway bridge (EHB) with rubber bearing support piers to mitigate damages of the bridge during the severe earthquake ground motion. The dynamic calculating model and equation of motion for the EHB system are set up theoretically and the LQR semi-active control algorithm of seismic response for the EHB system is developed to reduce effectively the responses of the structure. The non-linear calculation model of the piers that rigid degradation is considered and numerical simulative calculation are carried out by Matlab program. The number and location as well as the maximum control forces of the MR dampers, which are the most important parameters for the controlled system, are determined and the rubber bearing and connection forms of the damper play also important rule in the control efficiency. A real EHB structure that is located in Anshan city, Liaoning province in China is used as an example to be calculated under different earthquake records. The results of the calculation show that it is effective to reduce seismic responses of the EHB system by combining the rubber bearing isolation with semi-active MR control technique under the earthquake ground motion. The locations of MR dampers and structural parameters will influence seriously to the effects of structural vibration control.

Yan, Shi; Zhang, Hai

2005-05-01

153

Vibration Response Imaging as a New Tool for Interventional-Bronchoscopy Outcome Assessment: A Prospective Pilot Study  

Microsoft Academic Search

Background: In many patients, the benefit of interventional bronchoscopy cannot be appropriately objectified. Objectives: We investigated a new technique, vibration response imaging (VRI), for breathing sound mapping to determine whether it could provide additional, valuable objective qualitative and quantitative information in central airway obstruction (CAO) and patient outcome following interventional bronchoscopy. Methods: VRI images from 83 patients with suspected central

Heinrich D. Becker; Matthias Slawik; Teruomi Miyazawa; Merav Gat

2009-01-01

154

Vibration signature analysis of multistage gear transmission  

NASA Technical Reports Server (NTRS)

An analysis is presented for multistage multimesh gear transmission systems. The analysis predicts the overall system dynamics and the transmissibility to the gear box or the enclosed structure. The modal synthesis approach of the analysis treats the uncoupled lateral/torsional model characteristics of each stage or component independently. The vibration signature analysis evaluates the global dynamics coupling in the system. The method synthesizes the interaction of each modal component or stage with the nonlinear gear mesh dynamics and the modal support geometry characteristics. The analysis simulates transient and steady state vibration events to determine the resulting torque variations, speeds, changes, rotor imbalances, and support gear box motion excitations. A vibration signature analysis examines the overall dynamic characteristics of the system, and the individual model component responses. The gear box vibration analysis also examines the spectral characteristics of the support system.

Choy, F. K.; Tu, Y. K.; Savage, M.; Townsend, D. P.

1989-01-01

155

Minimizing vibration response of cylindrical shells through layout optimization of passive constrained layer damping treatments  

NASA Astrophysics Data System (ADS)

A layout optimization of passive constrained layer damping (PCLD) treatment for minimizing the vibration response of cylindrical shells is presented with consideration of broadband transverse force excitation. The equations governing the displacement responses, relating the integrated out-of-plane displacement over the whole structural volume, i.e., the structural volume displacement (SVD), of a cylindrical shell to structural parameters of base structure and multiple PCLD patches, are derived using the energy approach and assumed-mode method. Genetic algorithm (GA) based penalty function method is employed to find the optimal layout of rectangular PCLD patches with aim to minimize the SVD of the PCLD-treated cylindrical shell. Optimization solutions of the locations of patches for PCLD treatment are obtained under the constraint of total amount of PCLD materials in terms of percentage added weight to the base structure. Effects due to number of patches, their aspect ratios, and total amount of added PCLD weight are also studied. Examination of the optimal layouts reveals that the patches tend to increase their coverage in the axial direction and distribute over the whole surface of the cylindrical shell for optimal SVD reduction.

Zheng, H.; Cai, C.; Pau, G. S. H.; Liu, G. R.

2005-01-01

156

Display of response characteristics of seismic source arrays  

SciTech Connect

In seismic exploration wherein an array of seismic sources is moved along a line of exploration on the earth's surface and the reflections and/or refractions of seismic energy from the sources are recorded as seismograms, a method of displaying the response characteristics of the array is described which consists of: determining the amplitude response of the array at a plurality of locations at different azimuth angles and at different dip angles from the array; selecting equal values of determined amplitude response; and displaying contours of the equal values of amplitude response as a function of azimuth and dip angle in a stereoscopic polar projection.

Bowman, B.F.; Pann, K.; Pedeker, M.S.

1986-05-20

157

The Influence of Crystal Orientation on Vibration Characteristics of DD6 Nickel-Base Single Crystal superalloy Turbine Blade  

NASA Astrophysics Data System (ADS)

Modeling of a nickel-base single crystal superalloy turbine blade which accounts for material orthotropy is carried out to investigate the influence of axial direction and randomness crystallographic orientation on the dynamic natural frequency. In this paper, the natural frequency of the blade is calculated by the finite element method based on the commercial software ABAQUS. The results show that the deviation of the axial directions has a significant effect on the lower frequency as well as on the higher frequency, while the randomness in crystallographic orientations has a great impact only on higher order frequency. It is necessary to take the crystal orientation into account as an optimized factor and the variation of the vibration characteristics can be predicted.

Wen, Zhixun; Mao, Huanze; Yue, Zhufeng; Wang, Baizhi

2013-11-01

158

Characterization of the frequency and muscle responses of the lumbar and thoracic spines of seated volunteers during sinusoidal whole body vibration.  

PubMed

Whole body vibration has been postulated to contribute to the onset of back pain. However, little is known about the relationship between vibration exposure, the biomechanical response, and the physiological responses of the seated human. The aim of this study was to measure the frequency and corresponding muscle responses of seated male volunteers during whole body vibration exposures along the vertical and anteroposterior directions to define the transmissibility and associated muscle activation responses for relevant whole body vibration exposures. Seated human male volunteers underwent separate whole body vibration exposures in the vertical (Z-direction) and anteroposterior (X-direction) directions using sinusoidal sweeps ranging from 2 to 18?Hz, with a constant amplitude of 0.4?g. For each vibration exposure, the accelerations and displacements of the seat and lumbar and thoracic spines were recorded. In addition, muscle activity in the lumbar and thoracic spines was recorded using electromyography (EMG) and surface electrodes in the lumbar and thoracic region. Transmissibility was determined, and peak transmissibility, displacement, and muscle activity were compared in each of the lumbar and thoracic regions. The peak transmissibility for vertical vibrations occurred at 4?Hz for both the lumbar (1.55?±?0.34) and thoracic (1.49?±?0.21) regions. For X-directed seat vibrations, the transmissibility ratio in both spinal regions was highest at 2?Hz but never exceeded a value of 1. The peak muscle response in both spinal regions occurred at frequencies corresponding to the peak transmissibility, regardless of the direction of imposed seat vibration: 4?Hz for the Z-direction and 2-3?Hz for the X-direction. In both vibration directions, spinal displacements occurred primarily in the direction of seat vibration, with little off-axis motion. The occurrence of peak muscle responses at frequencies of peak transmissibility suggests that such frequencies may induce greater muscle activity, leading to muscle fatigue, which could be a contributing mechanism of back pain. PMID:25010637

Baig, Hassam A; Dorman, Daniel B; Bulka, Ben A; Shivers, Bethany L; Chancey, Valeta C; Winkelstein, Beth A

2014-10-01

159

Probabilistic analysis of mean-response along-wind induced vibrations on wind turbine towers using wireless network data sensors  

NASA Astrophysics Data System (ADS)

Wind turbine systems are attracting considerable attention due to concerns regarding global energy consumption as well as sustainability. Advances in wind turbine technology promote the tendency to improve efficiency in the structure that support and produce this renewable power source, tending toward more slender and larger towers, larger gear boxes, and larger, lighter blades. The structural design optimization process must account for uncertainties and nonlinear effects (such as wind-induced vibrations, unmeasured disturbances, and material and geometric variabilities). In this study, a probabilistic monitoring approach is developed that measures the response of the turbine tower to stochastic loading, estimates peak demand, and structural resistance (in terms of serviceability). The proposed monitoring system can provide a real-time estimate of the probability of exceedance of design serviceability conditions based on data collected in-situ. Special attention is paid to wind and aerodynamic characteristics that are intrinsically present (although sometimes neglected in health monitoring analysis) and derived from observations or experiments. In particular, little attention has been devoted to buffeting, usually non-catastrophic but directly impacting the serviceability of the operating wind turbine. As a result, modal-based analysis methods for the study and derivation of flutter instability, and buffeting response, have been successfully applied to the assessment of the susceptibility of high-rise slender structures, including wind turbine towers. A detailed finite element model has been developed to generate data (calibrated to published experimental and analytical results). Risk assessment is performed for the effects of along wind forces in a framework of quantitative risk analysis. Both structural resistance and wind load demands were considered probabilistic with the latter assessed by dynamic analyses.

Velazquez, Antonio; Swartz, Raymond A.

2011-04-01

160

Towards higher accuracy for ECM hybridized with low-frequency vibrations using the response surface methodology  

Microsoft Academic Search

The present work addresses the improvement of machining accuracy in ECM by hybridizing the process by low-frequency vibrations. The study highlights the development of mathematical models for correlating the inter relationships of various machining parameters such as applied voltage, feed rate, back pressure and vibration amplitude on overcut and conicity for achieving high controlled accuracy. This work is based on

S. J. Ebeid; M. S. Hewidy; T. A. El-Taweel; A. H. Youssef

2004-01-01

161

Occurrence of intimal thickening of the peripheral arteries in response to local vibration  

Microsoft Academic Search

Experiments were performed to elucidate a possible mechanism for the peripheral circulatory disturbance caused by vibration. Rats were exposed to local vibration (60 Hz, 5 G) on their hind legs for four hours a day for 30 days or 90 days. With exposure for 30 days the small arteries at the exposed site did not change. With exposure for 90

A Okada; R Inaba; T Furuno

1987-01-01

162

A laboratory study to quantify the biomechanical responses to whole-body vibration: The influence on balance, reflex response, muscular activity and fatigue  

Microsoft Academic Search

To determine the acute effects of whole-body vibration (WBV) on the sensorimotor system and potentially on the stability of the spine, different biomechanical responses were tested before and after 60min of sitting, with and without vertical WBV, on four different days. Postures adopted while sitting and the simulated WBV exposure corresponded to large mining load haul dump (LHD) vehicles as

Brenda R. Santos; Christian Larivière; Alain Delisle; André Plamondon; Paul-Émile Boileau; Daniel Imbeau

2008-01-01

163

A study of a nonlinear vibration isolator with a quasi-zero stiffness characteristic  

NASA Astrophysics Data System (ADS)

A vibration isolator consisting of a vertical linear spring and two nonlinear pre-stressed oblique springs is considered in this paper. The system has both geometrical and physical nonlinearity. Firstly, a static analysis is carried out. The softening parameter leading to quasi-zero dynamic stiffness at the equilibrium position is obtained as a function of the initial geometry, pre-stress and the stiffness of the springs. The optimal combination of the system parameters is found that maximises the displacement from the equilibrium position when the prescribed stiffness is equal to that of the vertical spring alone. It also satisfies the condition that the dynamic stiffness only changes slightly in the neighbourhood of the static equilibrium position. For these values, a dynamical analysis of the isolator under asymmetric excitation is performed to quantify the undesirable effects of the nonlinearities. It includes considering the possibilities of the appearance of period-doubling bifurcation and its development into chaotic motion. For this purpose, approximate analytical methods and numerical simulations accompanied with qualitative methods including phase plane plots, Poincaré maps and Lyapunov exponents are used. Finally, the frequency at which the first period-doubling bifurcation appears is found and the effect of damping on this frequency determined.

Kovacic, Ivana; Brennan, Michael J.; Waters, Timothy P.

2008-08-01

164

RESPONSE CHARACTERISTICS OF A DEAD-CELL BOD SENSOR  

Microsoft Academic Search

Bacillus subtilis cells, thermally killed by exposing dried cells to 280°C for 2.5mins, were used for fabricating the biofilm attached to a dissolved oxygen probe. The dead cell biosensor showed good sensing characteristics for the BOD of aqueous organic solutions and wastewaters in regard to its response and recovery times, reproducibility and stability. It has a significantly long life span

Zhenrong Qian; T. C Tan

1998-01-01

165

The experimental investigation of bounce characteristics of ACV responsive skirt  

NASA Astrophysics Data System (ADS)

This paper presents some experimental results on the bounce characteristics of the bag-finger responsive skirt and on skirt frequency response under cushion pressure excitation obtained in a large-scale box facility. The influence of some parameters on the amplitude and frequency of the skirt bounce motion and the amplitude of the cushion pressure oscillation were explored, and the corresponding bounce boundary curves are given. Some interesting nonlinear phenomena related to the skirt instability in the time domain response are presented. The mechanism for skirt bounce and the important parameters affecting skirt dynamic stability are examined, and some means for eliminating skirt bounce are introduced.

Zhou, W. L.; Ma, T.

166

Modeling and Analysis of Composite Wing Sections for Improved Aeroelastic and Vibration Characteristics Using Smart Materials  

NASA Technical Reports Server (NTRS)

The objective of this research is to develop analysis procedures to investigate the coupling of composite and smart materials to improve aeroelastic and vibratory response of aerospace structures. The structural modeling must account for arbitrarily thick geometries, embedded and surface bonded sensors and actuators and imperfections, such as delamination. Changes in the dynamic response due to the presence of smart materials and delaminations is investigated. Experiments are to be performed to validate the proposed mathematical model.

Chattopadhyay, Aditi

1996-01-01

167

Frequency response characteristics and response spectra of base-isolated and un-isolated structures  

SciTech Connect

The transmissibility of seismic loads through a linear base-isolation system is analyzed using an impedance method. The results show that the system acts like a {open_quotes}low-pass{close_quotes} filter. It attenuates high-frequency loads but passes through low-frequency ones. The filtering effect depends on the vibration frequencies and damping of the isolated structure and the isolation system. This paper demonstrates the benefits and design principles of base isolation by comparing the transmissibilities and response spectra of isolated and un-isolated structures. Parameters of typical isolated buildings and ground motions of the 1994 Northridge earthquake are used for the demonstration.

Mok, G.C. [Lawrence Livermore National Lab., CA (United States); Namba, H. [Shimizu Corporation, Tokyo (Japan)

1995-07-06

168

Response calculations of electronic and vibrational transitions in molecular oxygen induced by interaction with noble gases.  

PubMed

The Einstein coefficient for the singlet oxygen emission a1Deltag-->X3Sigmag- at lambda=1270 nm and b1Sigmag+-->X3Sigmag- emission at lambda=750 nm were calculated by quadratic response (QR) multiconfiguration self-consisted field (MCSCF) method for a number of collision complexes O2+M, where M=He, Ne, Ar. Interaction with He clusters was studied in order to simulate cooperative effect of the environment on the oxygen emission. Calculations of the dipole transition moment for the Noxon band, b1Sigmag+-a1Deltag, by linear response (LR) MCSCF method were also performed for a number of collision complexes. Spin-orbit coupling (SOC) between the b1Sigmag+ and X3Sigmag- (MS=0) states does not change much upon collisions, thus the a-X transition borrows intensity mostly from the collision-induced Noxon band b-a. The a-X intensity borrowing from the Schumann-Runge transition is negligible. The calculations show that the b-a and a-X transition probabilities are enhanced approximately by 10(5) and 10(3) times by O2+M collisions. An order of magnitude differences occur for both transitions for noble gases with large difference in polarizability. A strong cooperative effect is obtained when few He atoms perturb the oxygen molecule. Depending on mutual orientation of the partners it can be a complete quenching of the a-->X emission or strong non-additive enhancement. Collision-induced infrared vibrational transitions in a number of molecular oxygen excited states were studied and shown to be state selective. PMID:14607236

Minaev, Boris F; Kobzev, G I

2003-12-01

169

Neuromotor Transmissibility of Horizontal Seatpan Vibration  

E-print Network

on off-road vehicles, which include industrial vehicles and earth moving machinery. The response characteristics of occupants exposed to whole body vibration were investigated based on four different modes of transmission. Based on the different... as the ratio of accelerations measured at different levels of spine to the input seat acceleration. Experimental studies have reported consistent trends for occupants exposed to vertical seatpan vibration. Based on the transmission functions, the resonance...

Channamallu, Raghu Ram

2007-12-16

170

Influence of resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion  

NASA Astrophysics Data System (ADS)

The influence of acoustic resonators on the acoustic and propulsion performance characteristics of a ramjet ejector chamber under conditions with vibration hydrogen combustion was experimentally examined. In the study, resonators having identical throats and different cavity diameters were used. For fixed-volume resonators the best propulsion performance characteristics were achieved in the case in which the cavity diameter differed little from the resonator throat diameter.

Potapkin, A. V.; Moskvichev, D. Yu.

2008-09-01

171

Vibration and damping characteristics of composite laminates using shear deformable finite element  

SciTech Connect

The effects of transverse shear deformation on dynamic characteristics of composite laminated plates have been investigated. Complex modulus of an orthotropic lamina is employed to study damping effect and a modal approach to the resultant complex eigenvalue problem is introduced to save a considerable amount of computation time. The present results are in a good agreement with the solution of the modal strain energy method (MSE). The damping is very high when the composite laminated plates are subject to large transverse shear deformation.

Koo, K.N.; Lee, I. [Korea Advanced Institute of Science and Technology, Taejon (Korea, Republic of). Dept. of Aerospace Engineering

1993-12-31

172

Effects of Vibration and G-Loading on Heart Rate, Breathing Rate, and Response Time  

NASA Technical Reports Server (NTRS)

Aerospace and applied environments commonly expose pilots and astronauts to G-loading and vibration, alone and in combination, with well-known sensorimotor (Cohen, 1970) and performance consequences (Adelstein et al., 2008). Physiological variables such as heart rate (HR) and breathing rate (BR) have been shown to increase with G-loading (Yajima et al., 1994) and vibration (e.g. Guignard, 1965, 1985) alone. To examine the effects of G-loading and vibration, alone and in combination, we measured heart rate and breathing rate under aerospace-relevant conditions (G-loads of 1 Gx and 3.8 Gx; vibration of 0.5 gx at 8, 12, and 16 Hz).

Godinez, Angelica; Ayzenberg, Ruthie; Liston, Dorian B.; Stone, Leland S.

2013-01-01

173

The nonlinear forced response characteristics of contained fluids in microgravity  

NASA Technical Reports Server (NTRS)

An experimental study of the change in the lateral slosh behavior of contained fluids between earth and space is presented. The experimental apparatus used to determine the slosh characteristics is described and a nonlinear analytic model of a coupled fluid/spacecraft system is outlined. The forced response characteristics of silicon oil and distilled water in cylinder tanks with either a flat or spherical bottom are reported and discussed. A comparison of the measured earth and space results identifies and highlights the effects of gravity on the linear and nonlinear slosh behavior of these fluids.

Vanschoor, M. C.; Crawley, E. F.

1992-01-01

174

Investigation of vibration characteristics of the ligamentous lumbar spine using the finite element approach.  

PubMed

A nonlinear, three-dimensional finite element model of the ligamentous L4-S1 segment was developed to analyze the dynamic response of the spine in the absence of damping. The effects of the upper body mass were simulated by including a mass of 40 kg on the L4 vertebral body. The modal analyses of the model indicated a resonant frequency of 17.5 Hz in axial mode and 3.8 Hz in flexion-extension mode. Accordingly, the predicted responses for the cyclic load of -400 +/- 40 N applied at four different frequencies (5, 11, 16.5, and 25 Hz) were compared with the corresponding results for axial compressive static loads (-360, and -440 N). As compared to the static load cases, the predicted responses were higher for the cyclic loading. For example, the effect of cyclic load at 11 Hz was to produce significant changes (9.7-19.0 percent) in stresses, loads transmitted through the facets, intradiscal pressure (IDP), disk bulge, as compared to the static load predictions. The responses were found to be frequency dependent as well; supporting the in vivo observations of other investigators that the human spine has a resonant frequency. For example, the 11 Hz model (DYN11) compared to the DYN5 model showed an increase in majority of the predicted parameters. The parameters showed an increase with frequency until 17.5 Hz (resonant frequency of the model); thereafter a decrease at 25 Hz.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7869712

Goel, V K; Park, H; Kong, W

1994-11-01

175

Response characteristics of high-performance photorefractive mesogenic composites  

NASA Astrophysics Data System (ADS)

This article presents high-speed photorefractive high-liquid crystal (H-LC) and low-molar-mass liquid crystal (L-LC) mixtures (HL-LCMs) which exhibit the fastest response time achieved so far (15 ms), while maintaining a large gain coefficient of 270 cm-1, high resolution, and the required low operating voltage. The response time strongly depended on the viscosity of the HL-LCMs, which was varied by controlling the molecular weight of the H-LC. These superior characteristics were achieved by decreasing the molecular weight of the H-LC.

Ono, Hiroshi; Hanazawa, Akihiro; Kawamura, Tomomi; Norisada, Hideki; Kawatsuki, Nobuhiro

1999-08-01

176

Characteristic Timescales of Shoreface Response to Sea-Level Rise  

NASA Astrophysics Data System (ADS)

On open ocean, wave-dominated, sandy coasts, the response of the shore to sea-level rise is dominated not by inundation, but rather by the dynamic response of sediment transport processes to perturbations of the sea level. In a regime of sea level change, the predominant response of the wave-dominated shoreface depends upon the time-dependent response of the shoreface itself to changes in sea level as well as the potential changes to the shoreline. On a barrier coast, persistent, long-term changes to the shoreline are caused by storm overwash, which transports marine sediment landward, moving the shoreline boundary. Raised sea levels increase the impact and frequency of this overwash as relative barrier elevation is reduced. Overall, sediment transport processes on the shoreface remain poorly understood, complicating predictions of equilibrium shoreface shapes and even net sediment transport directions. However, presuming an equilibrium geometry, energetics-based, time-averaged relationships for cross-shore sediment transport provide a framework to understand the characteristic rates and types of shoreface response to perturbations to either the sea level or the shoreline boundary. In the case of a sea-level rise, we find that the dominant perturbation for a barrier system is not the sea-level rise itself, but rather the movement of the shoreline by overwash. The characteristic response time of the shoreface itself increases significantly at depth, suggesting that the lower shoreface response to a sea level change can be significantly delayed. We estimate the importance of extreme events on shoreface evolution by analyzing decade-long data series of wave characteristics along different open ocean coasts with barriers (Florida Gulf Coast, North Carolina, Marthas Vineyard). Analogous to the effect of floods in fluvial systems, although storm events can move significant sediment, the infrequency of the larger events limits their effect on the shoreface-the morphologically significant event for shoreface evolution has a return interval of less than two years. However, numerical simulations of tens of thousands of synthetic storm strikes at the same locations suggest that the return interval of storm events expected to cause significant overwash is longer, on the order of at least 50 years. To study the interactions between the characteristic timescales of shoreface evolution and barrier overwash, we apply a numerical model of barrier profile evolution that couples shoreface evolution with barrier overwash. This integrated model provides a tool to understand the response of barrier systems to changes in sea level over the late Holocene to the modern. The model also investigates the potential behavior of barrier systems as they (and their human occupants) respond to predicted increased rates of sea-level rise over the coming centuries.

Ashton, A. D.; Ortiz, A.; Lane, P.; Donnelly, J. P.

2011-12-01

177

Damage identification and health monitoring of structural and mechanical systems from changes in their vibration characteristics: A literature review  

SciTech Connect

This report contains a review of the technical literature concerning the detection, location, and characterization of structural damage via techniques that examine changes in measured structural vibration response. The report first categorizes the methods according to required measured data and analysis technique. The analysis categories include changes in modal frequencies, changes in measured mode shapes (and their derivatives), and changes in measured flexibility coefficients. Methods that use property (stiffness, mass, damping) matrix updating, detection of nonlinear response, and damage detection via neural networks are also summarized. The applications of the various methods to different types of engineering problems are categorized by type of structure and are summarized. The types of structures include beams, trusses, plates, shells, bridges, offshore platforms, other large civil structures, aerospace structures, and composite structures. The report describes the development of the damage-identification methods and applications and summarizes the current state-of-the-art of the technology. The critical issues for future research in the area of damage identification are also discussed.

Doebling, S.W.; Farrar, C.R.; Prime, M.B.; Shevitz, D.W.

1996-05-01

178

Energy conservation in the transient response of nonlinear beam vibration problems subjected to pulse loading - A numerical approach  

NASA Technical Reports Server (NTRS)

The nonlinear vibration response of a double cantilevered beam subjected to pulse loading over a central sector is studied. The initial response is generated in detail to ascertain the energetics of the response. The total energy is used as a gauge of the stability and accuracy of the solution. It is shown that to obtain accurate and stable initial solutions an extremely high spatial and time resolution is required. This requirement was only evident through an examination of the energy of the system. It is proposed, therefore, to use the total energy of the system as a necessary stability and accuracy criterion for the nonlinear response of conservative systems. The results also demonstrate that even for moderate nonlinearities, the effects of membrane forces have a significant influence on the system. It is also shown that while the fundamental response is contained in a first mode envelope, the fluctuations caused by the higher order modes must be resolved.

Moyer, E. T., Jr.

1984-01-01

179

Vibration characteristics of Z-ring-stiffened 60 deg conical shell models of a planetary entry spacecraft  

NASA Technical Reports Server (NTRS)

An experimental investigation of the vibration characteristics of a 60 deg conical shell model of a planetary entry vehicle is described and the results presented. Model configurations include the shell with or without one or two Z-ring stiffeners and with or without a simulated payload. Tests were conducted with the model clamped at the small diameter and with the model suspended at the simulated payload. Additionally, calculated results obtained from application of several analytical procedures reported in the literature are presented together with comparisons between experimental and calculated frequencies and meridional mode shapes. Generally, very good frequency agreement between experimental and calculated results was obtained for all model configurations. For small values of circumferential mode number, however, the frequency agreement decreased as the number of ring stiffeners increased. Overall agreement between experimental and calculated mode shapes was generally good. The calculated modes usually showed much larger curvatures in the vicinity of the rings than were observed in the experimentally measured mode shapes. Dual resonances associated with modal preference were noted for the shell without Z-ring stiffeners, whereas the addition of stiffeners produced resonances for which the model responded in two or more modes over different sections of the shell length.

Naumann, E. C.; Mixon, J. S.

1971-01-01

180

A STUDY ON THE THERMAL RESPONSE CHARACTERISTICS OF THE FLOOR OF HYDRONIC FLOOR HEATING SYSTEMS  

Microsoft Academic Search

Many studies have been performed on floor heating systems. However, there is almost no data on the response characteristics immediately after the start of the operation. In Japan, floor heating systems are often intermittently operated, so these response characteristics are important. In this research, the heat transmission response, the heat absorption response, and other response characteristics are simulated just after

Aiko KOBAYASHI; Kimiko KOHRI

181

On the characteristics of fault-induced rotor-dynamic bifurcations and nonlinear responses  

E-print Network

are characteristically non-periodic and broadband and of multi-mode structure. It is very difficult to This dissertation follows the style and format of Journal of Vibration and Acoustics. 2 discern these dynamical states using their time waveforms and measurement... are characteristically non-periodic and broadband and of multi-mode structure. It is very difficult to This dissertation follows the style and format of Journal of Vibration and Acoustics. 2 discern these dynamical states using their time waveforms and measurement...

Yang, Baozhong

2004-11-15

182

Prevalence and Characteristics of Vibrator Use by Women in the United States: Results from a Nationally Representative Study  

Microsoft Academic Search

Introduction. Although vibrators are commonly recommended by clinicians as adjunct to treatment for female sexual dysfunction, and for sexual enhancement, little is known about their prevalence or correlates of use. Aim. The aim of this study was to determine the lifetime and recent prevalence of women's vibrator use during masturbation and partnered sex, and the correlates of use related to

Debra Herbenick; Michael Reece; Stephanie Sanders; Brian Dodge; Annahita Ghassemi; J. Dennis Fortenberry

2009-01-01

183

Investigation of Dynamic Force/Vibration Transmission Characteristics of Four-Square Type Gear Durability Test Machines  

NASA Technical Reports Server (NTRS)

In this study, design requirements for a dynamically viable, four-square type gear test machine are investigated. Variations of four-square type gear test machines have been in use for durability and dynamics testing of both parallel- and cross-axis gear set. The basic layout of these machines is illustrated. The test rig is formed by two gear pairs, of the same reduction ratio, a test gear pair and a reaction gear pair, connected to each other through shafts of certain torsional flexibility to form an efficient, closed-loop system. A desired level of constant torque is input to the circuit through mechanical (a split coupling with a torque arm) or hydraulic (a hydraulic actuator) means. The system is then driven at any desired speed by a small DC motor. The main task in hand is the isolation of the test gear pair from the reaction gear pair under dynamic conditions. Any disturbances originated at the reaction gear mesh might potentially travel to the test gearbox, altering the dynamic loading conditions of the test gear mesh, and hence, influencing the outcome of the durability or dynamics test. Therefore, a proper design of connecting structures becomes a major priority. Also, equally important is the issue of how close the operating speed of the machine is to the resonant frequencies of the gear meshes. This study focuses on a detailed analysis of the current NASA Glenn Research Center gear pitting test machine for evaluation of its resonance and vibration isolation characteristics. A number of these machines as the one illustrated has been used over last 30 years to establish an extensive database regarding the influence of the gear materials, processes surface treatments and lubricants on gear durability. This study is intended to guide an optimum design of next generation test machines for the most desirable dynamic characteristics.

Kahraman, Ahmet

2002-01-01

184

Noise and vibration  

NASA Technical Reports Server (NTRS)

The characteristics of acoustic energy and protection of humans from noise during space flight are described. Vibration characteristic factors are also discussed, including the variety of vibration, systems and resonance, spacecraft operations, biodynamics, physiological and psychological effects, and subjective reactions. The criteria and limits for human exposure are cited.

Vongierke, H. E.; Nixon, C. W.; Guignard, J. C.

1975-01-01

185

Application of a large scale state estimator to the vibrational response of a mechanical structure. [SEALS  

Microsoft Academic Search

The SEALS (State Estimator for Large Systems) computer code was applied to the estimation of displacement time histories of points on a vibrating mechanical structure given noisy measurements at two locations on the structure. The goal was to demonstrate the feasibility of determining the motion of internal members of the structure given only noisy measurements from the exterior and a

Lager

1980-01-01

186

NEUROMOTOR RESPONSE TO WHOLE BODY VIBRATION TRANSMISSIBILITY IN THE HORIZONTAL DIRECTION AND ITS MATHEMATICAL MODEL  

E-print Network

-dynamic shaker was used to create fore-aft vibration. Data from tri-axial accelerometers on the seatpan and attached to the skin at the T10 spinous process, an electrogoniometer across the lumbar spine, electromyography (EMG) on the erector spinae (ES) muscles...

Hanumanthareddygari, Vinay

2010-09-02

187

Structural response of a ship in severe seas considering global hydroelastic vibrations  

Microsoft Academic Search

In this paper, a consistent structural analysis procedure to estimate the global and local load effects considering symmetric and anti-symmetric hydroelastic vibrations in high waves is proposed. The procedure consists of motion analysis followed by a structural analysis. First, a system equation of motion by modal approach is set-up and solved in the time domain. In the load evaluations, not

Kazuhiro Iijima; Tetsuya Yao; Torgeir Moan

2008-01-01

188

The Effect of Vibration on Postural Response of Down Syndrome Individuals on the Seesaw  

ERIC Educational Resources Information Center

In order to better understand the role of proprioception in postural adjustments on unstable surfaces, we analyzed the effect of vibration on the pattern of muscle activity and joint displacements (ankle, knee and hip) of eight intellectually normal participants (control group-CG) and eight individuals with Down syndrome (DS) while balancing on…

Carvalho, Regiane Luz; Almeida, Gil Lucio

2009-01-01

189

EMG and Heart Rate Responses Decline within 5 Days of Daily Whole-Body Vibration Training with Squatting  

PubMed Central

In this study, we examined the acute effects of a 5-day daily whole-body vibration (WBV) training on electromyography (EMG) responses of the m. rectus femoris and m. gastrocnemius lateralis, heart rate (HR, continuously recorded), and blood lactate levels. The purpose of the study was to investigate the adaptation of muscle activity, heart rate and blood lactate levels during 5 days of daily training. Two groups of healthy male subjects performed either squat exercises with vibration at 20 Hz on a side alternating platform (SE+V, n?=?20, age ?=?31.9±7.5 yrs., height ?=?178.8±6.2 cm, body mass ?=?79.2±11.4 kg) or squat exercises alone (SE, n?=?21, age ?=?28.4±7.3 years, height ?=?178.9±7.4 cm, body mass ?=?77.2±9.7 kg). On training day 1, EMG amplitudes of the m. rectus femoris were significantly higher (P<0.05) during SE+V than during SE. However, this difference was no longer statistically significant on training days 3 and 5. The heart rate (HR) response was significantly higher (P<0.05) during SE+V than during SE on all training days, but showed a constant decline throughout the training days. On training day 1, blood lactate increased significantly more after SE+V than after SE (P<0.05). On the following training days, this difference became much smaller but remained significantly different. The specific physiological responses to WBV were largest on the initial training day and most of them declined during subsequent training days, showing a rapid neuromuscular and cardiovascular adaptation to the vibration stimulus. PMID:24905721

Rosenberger, Andre; Liphardt, Anna-Maria; Bargmann, Arne; Muller, Klaus; Beck, Luis; Mester, Joachim; Zange, Jochen

2014-01-01

190

Dose-response relation for vascular disorders induced by vibration in the fingers of forestry workers  

Microsoft Academic Search

OBJECTIVES--To study the relation between the prevalence of vascular disorders (white finger) and vibration exposure in a group of 222 forestry workers, of whom 164 (73.9%) had work experience limited to antivibration (AV) chain saws only and 58 (26.1%) had operated both non-AV and AV chain saws. METHODS--The chain saw operators and 195 control workers never exposed to hand transmitted

M Bovenzi; A Franzinelli; R Mancini; M G Cannavà; M Maiorano; F Ceccarelli

1995-01-01

191

An Experimental Comparison of Transmission Vibration Responses from OH58 and AH1 Helicopters  

Microsoft Academic Search

Statistical analyses of transmission vibration patterns from an AH-1 Cobra helicopter were previously re- ported. Fourteen steady-state maneuvers were ana- lyzed using multi-factor analysis of covariance. Based on triaxial recordings, it was found that only two maneuvers displayed reliably stationary time-series: low and high power forward climb. Principal Com- ponents Analysis of the triaxial RMS data was shown to aggregate

Edward M. Huff; Irem Y. Tumer; Marianne Mosher

192

Quasi-Static and Dynamic Response Characteristics of F-4 Bias-Ply and Radial-Belted Main Gear Tires  

NASA Technical Reports Server (NTRS)

An investigation was conducted at Langley Research Center to determine the quasi-static and dynamic response characteristics of F-4 military fighter 30x11.5-14.5/26PR bias-ply and radial-belted main gear tires. Tire properties were measured by the application of vertical, lateral, and fore-and-aft loads. Mass moment-of-inertia data were also obtained. The results of the study include quasi-static load-deflection curves, free-vibration time-history plots, energy loss associated with hysteresis, stiffness and damping characteristics, footprint geometry, and inertia properties of each type of tire. The difference between bias-ply and radial-belted tire construction is given, as well as the advantages and disadvantages of each tire design. Three simple damping models representing viscous, structural, and Coulomb friction are presented and compared with the experimental data. The conclusions discussed contain a summary of test observations.

Davis, Pamela A.

1997-01-01

193

Acceptance and control of aircraft interior noise and vibration  

NASA Technical Reports Server (NTRS)

Ride quality criteria for noise, vibration, and their combination in the helicopter cabin environment are discussed. Results are presented of laboratory and field studies of passenger responses to interior noise and vibration during the performance of a listening task and during reverie, as well as to the interaction of noise with multi-frequency and multi-axis vibration. A study of means for reducing helicopter interior noise based on analytical, experimental and flight studies of the near-field noise source characteristics of the aircraft, the transmission of noise through aircraft structures and the attenuation of noise by various noise control treatments is then presented which has resulted in a reduction of 3 dB in helicopter cabin noise. Finally, a model under development to evaluate passenger acceptance of a helicopter noise and vibration environment is indicated which incorporates the observed noise and vibration effects on comfort and is expected to provide insights for more effective noise and vibration control.

Stephens, D. G.; Leatherwood, J. D.

1980-01-01

194

EFFECTS OF 6-WEEK WHOLE BODY VIBRATION TRAINING ON THE REFLEX RESPONSE OF THE ANKLE MUSCLES: A RANDOMIZED CONTROLLED TRIAL  

PubMed Central

Background: The ligament sprain of the lateral ankle is the most frequent injury that occurs when participating in sports. Whole body vibration (WBV) is a training method that has been recently introduced as a rehabilitative tool for treatment of athletes. It has been hypothesized that the transmission of mechanical oscillations from the vibrating platform may lead to physiological changes in muscle spindles, joint mechanoreceptors, as well as improve balance. Propose: The aim of this study was to assess the effects of a 6?week WBV training program on the reflex response mechanism of the peroneus longus (PL), peroneus brevis (PB) and anterior tibialis (AT) muscles in ankle inversion at 30º from horizontal, in a static position. Methods: This study was a single?blinded and randomized controlled trial. Forty?four healthy, physically active participants were randomly split into two groups: the experimental group (n = 26) (the WBV training) and control group (n = 18). Reaction time (RT), maximum electromyographic (EMG) peak (peak EMG), time to the maximum peak EMG (peak EMG time) and reflex electrical activity of all the muscles were assessed before and after the WBV training through surface EMG. Results: After 6?weeks WBV training, there were no significant changes in the variables analysed for all the muscles involved. Conclusion: A 6?week WBV training does not improve the reflex response mechanism of the lateral stabilizing muscles of the ankle. Level of evidence: 1b PMID:23439725

Rubio, Jacobo A.; Ramos, Domingo J.; Esteban, Paula; Mendizabal, Susana; Jimenez, Fernando

2013-01-01

195

Good Vibrations  

NASA Technical Reports Server (NTRS)

A Small Business Innovation Research (SBIR) sponsorship from NASA's Dryden Flight Research Center, assisted MetroLaser, of Irvine, California, in the development of a self-aligned laser vibrometer system. VibroMet, capable of measuring surface vibrations in a variety of industries, provides information on the structural integrity and acoustical characteristics of manufactured products. This low-cost, easy-to-use sensor performs vibration measurement from distances of up to three meters without the need for adjustment. The laser beam is simply pointed at the target and the system then uses a compact laser diode to illuminate the surface and to subsequently analyze the reflected light. The motion of the surface results in a Doppler shift that is measured with very high precision. VibroMet is considered one of the many behind-the-scenes tools that can be relied on to assure the quality, reliability and safety of everything from airplane panels to disk brakes

2001-01-01

196

Existence of a stable resonance zone with nearly unchanging vibration characteristics for a near-field scanning optical microscope probe dipped partially into a liquid  

NASA Astrophysics Data System (ADS)

The vibration characteristics of a near-field scanning optical microscope (NSOM) probe, whose vibration was controlled by two-nodal-wedge method and tip was partially dipped into a liquid, were investigated theoretically and experimentally. The resonant frequency and the Q value of the NSOM probe were found to remain nearly unchanged irrespective of the dipping depth of the probe, if the probe was kept within a dipping depth range of 0.4˜1.0 mm. With the achievement of a high Q value, the existence of this stable resonance zone implies that bio-samples immersed in a liquid can be accurately and stably measured using a NSOM controlled by using two-nodal-wedge method.

Lee, Wonjun; Kim, Seyoung; Kim, Dae-Chan; O, Beom-Hoan; Park, Se-Geun; Lee, Seung Gol

2014-02-01

197

Seasonal variations in vibrational spectra of the sea surface nanolayer and their relation to characteristic parameters for phytoplankton activity  

NASA Astrophysics Data System (ADS)

The sea surface nanolayer is a very thin organic substance layer, down to monomolecular thickness. It is found on top of the sea surface microlayer, which in turn comprises roughly the uppermost millimeter of the water column. The nanolayer constitutes the actual interface between ocean and atmosphere and plays an important role in all exchange processes of matter and energy between ocean and atmosphere. Nevertheless, knowledge about formation and development of the sea surface nanolayer in the course of the year is very limited. In this study we present surface-specific observations of the sea surface nanolayer development over a period of three and a half years. Samples of the sea surface have been taken monthly at Boknis Eck Time Series Station (Eckernförde Bay, southwestern Baltic Sea) by screen sampling. From surface-sensitive vibrational spectra obtained by nonlinear sum frequency generation spectroscopy (SFG), information on amount, structure and composition of the organic nanolayer material was extracted. SFG has been introduced by us as a new method to study the ocean nanolayer quite recently [1,2]. The abundance of nanolayer material was found to follow a pronounced yearly periodicity, with larger amounts of material present from mid to end of summer. A substantial time lag of about 2.5 months between spring algal bloom maxima and abundance maxima of nanolayer material has been observed. In contrast to common perception, this shows that high phytoplankton abundance and pronounced nanolayers are not directly related to each other. Variations in the appearance of the spectra serve as indicators for changes in structure and chemical composition of the nanolayer. The accumulation of carbohydrate-rich material in late summer provides a possible explanation for the observed spectral changes. We propose that sloppy feeding of zooplankton as well as photochemical and/or microbial processing of organic material present in the microlayer is responsible for the periodicity of nanolayer intensity and its temporal shift with respect to other influential factors. References [1] K. Laß, G. Friedrichs, J. Geophys. Res. 116 (2011) C08042/1-15 [2] K. Laß, J. Kleber, G. Friedrichs, Limnol. Oceanogr.: Methods 8 (2010) 216-228

Laß, Kristian; Bange, Hermann W.; Friedrichs, Gernot

2013-04-01

198

Proceedings of the NARST 2009 Annual Meeting RESPONSE CHARACTERISTICS OF MIDDLE SCHOOL LEARNERS  

E-print Network

Proceedings of the NARST 2009 Annual Meeting RESPONSE CHARACTERISTICS OF MIDDLE SCHOOL LEARNERS their advantages and disadvantages. Student responses favored response framings focusing on the visual a central role in science education (Grosslight, Unger & Jay, 1991). Especially for younger learners

Moher, Tom

199

Nonlinear terahertz spectroscopy of electronic and vibrational responses in condensed matter systems  

E-print Network

In this work, I describe experiments utilizing high-field terahertz (THz) pulses to initiate nonlinear responses in several classes of materials. We have developed several methods for interrogating the nonlinear THz response ...

Hwang, Harold Young

2012-01-01

200

Experimental IR and Raman spectra and quantum chemical studies of molecular structures, conformers and vibrational characteristics of L-ascorbic acid and its anion and cation  

NASA Astrophysics Data System (ADS)

IR and spectra of the L-ascorbic acid ( L-AA) also known as vitamin C have been recorded in the region 4000-50 cm -1. In order to make vibrational assignments of the observed IR and Raman bands computations were carried out by employing the RHF and DFT methods to calculate the molecular geometries and harmonic vibrational frequencies along with other related parameters for the neutral L-AA and its singly charged anionic ( L-AA -) and cationic ( L-AA +) species. Significant changes have been found for different characteristics of a number of vibrational modes. The four ?(O-H) modes of the L-AA molecule are found in the order ?(O 9-H 10) > ?(O 19-H 20) > ?(O 7-H 8) > ?(O 14-H 15) which could be due to complexity of hydrogen bonding in the lactone ring and the side chain. The C dbnd O stretching wavenumber ( ?46) decreases by 151 cm -1 in going from the neutral to the anionic species whereas it increases by 151 cm -1 in going from the anionic to the cationic species. The anionic radicals have less kinetic stabilities and high chemical reactivity as compared to the neutral molecule. It is found that the cationic radical of L-AA is kinetically least stable and chemically most reactive as compared to its neutral and anionic species.

Yadav, R. A.; Rani, P.; Kumar, M.; Singh, R.; Singh, Priyanka; Singh, N. P.

2011-12-01

201

Vibrational Feedback Control.  

National Technical Information Service (NTIS)

This paper illustrates that in addition to closed loop pole placement, vibrational feedback control leads to a possibility of open loop zeros assignability. On this basis, the superior performance characteristics of periodic controllers are explained. (ER...

S. M. Meerkov

1986-01-01

202

Vibration characteristics and function of atelectatic segments in the tympanic membrane in fresh human cadaveric temporal bones.  

PubMed

Dimeric segments are commonly encountered in otological practice. They may be associated with a mild conductive hearing loss and often coexist with other tympanic membrane and middle ear abnormalities. Some otologists have advocated surgical management but the consequences of dimeric segment stiffening, shielding or excision and grafting on acoustic transfer to the stapes footplate has been poorly explored. In this study, laser Doppler vibrometry was used to measure vibrations at the tympanic membrane and the stapes footplate in the fresh cadaveric human temporal bone. The dimeric segment vibrates more than the adjacent, thicker normal tympanic membrane. Shielding or excision and grafting of the dimeric segment with thicker and stiffer materials has little effect on displacement at the stapes footplate. PMID:15113296

Morris, D P; Bance, M; Van Wijhe, R G

2004-04-01

203

A New Fiber-Optic Acoustic\\/Vibration Sensor — Characteristics and Application to Civil Structural Health Monitoring  

Microsoft Academic Search

A new fiber-optic acoustic\\/vibration sensor has been developed and applied to structural health monitoring. The sensor is based on a new theory “Doppler effect in flexible and expandable light-waveguide.” A very high sensitivity is achieved in the extremely wide frequency range. Principle, sensor configuration and sensitivity, measurement system and damage detection in the reinforced concrete structural models were described in

Kazuro Kageyama; Hideaki Murayama; Kiyoshi Uzawa

204

Free vibration response of two-dimensional magneto-electro-elastic laminated plates  

NASA Astrophysics Data System (ADS)

An approximate solution for the free vibration problem of two-dimensional magneto-electro-elastic laminates is presented to determine their fundamental behavior. The laminates are composed of linear homogeneous elastic, piezoelectric, or magnetostrictive layers with perfect bonding between each interface. The solution for the elastic displacements, electric potential, and magnetic potential is obtained by combining a discrete layer approach with the Ritz method. The model developed here is not dependent on specific boundary conditions, and it is presented as an alternative to the exact or analytical approaches which are limited to a very specific set of edge conditions. The natural frequencies and through-thickness modal behavior are computed for simply supported and cantilever laminates. Solutions for the simply supported case are compared with the known exact solution for piezoelectric laminates, and excellent agreement is obtained. The present approach is also validated by comparing the natural frequencies of a two-layer cantilever plate with known analytical solution and with results obtained using commercial finite element software.

Ramirez, Fernando; Heyliger, Paul R.; Pan, Ernian

2006-05-01

205

Flow-induced vibration and instability of some nuclear-reactor-system components. [PWR  

SciTech Connect

The high-velocity coolant flowing through a reactor system component is a source of energy that can induce component vibration and instability. In fact, many reactor components have suffered from excessive vibration and/or dynamic instability. The potential for detrimental flow-induced vibration makes it necessary that design engineers give detailed considerations to the flow-induced vibration problems. Flow-induced-vibration studies have been performed in many countries. Significant progress has been made in understanding the different phenomena and development of design guidelines to avoid damaging vibration. The purpose of this paper is to present an overview of the recent progress in several selected areas, to discuss some new results and to indentify future research needs. Specifically, the following areas will be presented: examples of flow-induced-vibration problems in reactor components; excitation mechanisms and component response characteristics; instability mechanisms and stability criteria; design considerations; and future research needs.

Chen, S.S.

1983-01-01

206

VIBRA: An interactive computer program for steady-state vibration response analysis of linear damped structures  

NASA Technical Reports Server (NTRS)

An interactive steady state frequency response computer program with graphics is documented. Single or multiple forces may be applied to the structure using a modal superposition approach to calculate response. The method can be reapplied to linear, proportionally damped structures in which the damping may be viscous or structural. The theoretical approach and program organization are described. Example problems, user instructions, and a sample interactive session are given to demonstate the program's capability in solving a variety of problems.

Bowman, L. M.

1984-01-01

207

Parametric Characteristic Analysis for Generalized Frequency Response Functions of Nonlinear Systems  

Microsoft Academic Search

In order to explicitly reveal the relationship between system frequency response functions and model parameters which define\\u000a system nonlinearities, and consequently unveil a direct connection from model parameters to system frequency response characteristics,\\u000a a parametric characteristic analysis approach is proposed for Volterra systems described by a nonlinear differential equation\\u000a (NDE). The parametric characteristics of the generalized frequency response functions (GFRFs)

Xing Jian Jing; Zi Qiang Lang; Stephen A. Billings

2009-01-01

208

Research on relation between bending stress and characteristic frequency of H-shaped beam by free vibration deflection  

NASA Astrophysics Data System (ADS)

In order to investigate a relation between a bending stress and a characteristic frequency of a beam, 4-point loading which had constant moment region was conducted to a beam with H shape configuration experimentally and numerically. H-shaped beam has many characteristic deformation modes. Axial tensile stress in the beam made its characteristic frequency higher, and compressive stress lower. In the experiment, some characteristic frequencies got higher by a bending stress, and the others stayed in a small frequency fluctuation. The distinction is anticipated as a capability to measure a bending stress of a beam by its characteristic frequencies.

Yoshida, Tsutomu; Watanabe, Takeshi

2014-05-01

209

Output frequency response function based design of additional nonlinear viscous dampers for vibration control of multi-degree-of-freedom systems  

NASA Astrophysics Data System (ADS)

This paper is concerned with the development of a new technique for the optimal placement and design of additional nonlinear viscous dampers for vibration control of Multi-Degree-Of-Freedom (MDOF) systems. The MDOF systems described by a multi-storey shear building model and subjected to harmonic loadings are first considered in the present study; then, the basic ideas of the design are extended to the cases of earthquake loadings. The studies are based on the concept of Output Frequency Response Function (OFRF) and associated methods proposed recently by the authors in control engineering and extend, for the first time, the well-established linear viscous damper optimal placement and design techniques for MDOF system vibration control to the nonlinear case. The design examples verify the effectiveness of the new technique, and demonstrate the beneficial effects of the designed additional nonlinear dampers on the MDOF system vibration control and the advantages of nonlinear viscous dampers over linear dampers in such applications.

Lang, Z. Q.; Guo, P. F.; Takewaki, I.

2013-09-01

210

Estimation of vibration power absorption density in human fingers.  

PubMed

The absorption of hand-transmitted vibration energy may be an etiological factor in vibration-induced disorders. The vibration power absorption density (VPAD) may be a better measure of energy than the total power absorption of the hand-arm system. The objectives of the present study are to develop a method to estimate the average absorption density in the fingers and to investigate its basic characteristics. Ten healthy male subjects were used in this study. The biodynamic response of the fingers in a power grip subjected to a broad-band random excitation was measured under three grip forces (15, 30, 50 N) and three push forces (35, 45, 50 N). The response was used to estimate the total finger energy absorption. The response, together with the finger volume, was also used to estimate the amount of tissue effectively involved in the absorption. Then, the average VPAD under constant-acceleration, constant-power density, constant-velocity vibration spectra, and 20 tool vibration spectra were calculated. The correlations between the VPAD and the unweighted and weighted accelerations (ISO 5349-1, 2001) were also examined. The VPAD depends on both the characteristics of the vibration spectrum and the biodynamic response of the finger-hand-arm system. The biodynamic response generally plays a more important role in determining the VPAD in the middle frequency range (31.5-400 Hz) than those at the low and high ends. The applied force significantly affected the VPAD. The finger VPAD was highly correlated to the unweighted acceleration. The average VPAD can be determined using the proposed experimental method. It can serve as an alternative tool to quantify the severity of the vibration exposure for studying vibration-induced finger disorders. PMID:16248315

Dong, Ren G; Wu, John Z; Welcome, Daniel E; McDowell, Thomas W

2005-10-01

211

Vibration response of spalled rolling element bearings: Observations, simulations and signal processing techniques to track the spall size  

NASA Astrophysics Data System (ADS)

Fatigue in rolling element bearings, resulting in spalling of the races and/or rolling elements, is the most common cause of bearing failure. The useful life of the bearing may extend considerably beyond the appearance of the first spall and a premature removal of the bearing from service can be very expensive, but on the other hand chances cannot be taken with safety of machines or personnel. Previous studies indicated that there might be two parts to the defect vibration signal of a spalled bearing, the first part being originating from the entry of the rolling element into the fault (de-stress) and the second part being due to the departure of the rolling element from the fault (re-stress). This is investigated in this paper using vibration signatures of seeded faults at different speeds. The acceleration signals resulting from the entry of the rolling element into the spall and exit from it were found to be of different natures. The entry into the fault can be described as a step response, with mainly low frequency content, while the impact excites a much broader frequency impulse response. The latter is the most noticeable and prominent event, especially when examining the high pass filtered response or the enveloped signal. In order to enable a clear separation of the two events, and produce an averaged estimate of the size of the fault, two approaches are proposed to enhance the entry event while keeping the impulse response. The first approach (joint treatment) utilizes pre-whitening to balance the low and high frequency energy, then octave band wavelet analysis to allow selection of the best band (or scale) to balance the two pulses with similar frequency content. In the second approach, a separate treatment is applied to the step and the impulse responses, so that they can be equally represented in the signal. Cepstrum analysis can be used to give an average estimate of the spacing between the entry and impact events, but the latter can also be assessed by an arithmetic estimation of the mean and standard deviation of the event separation for a number of realizations, in particular for the second approach. In order to determine the effects of various simulations and signal processing parameters on the estimated delay times, the entry and exit events were simulated as modified step and impulse responses with precisely known starting times. The simulation was also found useful in pointing to artefacts associated with the cepstrum calculation, which affect even the simulated signals, and have thus prompted modifications of the processing of real signals. The results presented for the two approaches give a reasonable approximation of the measured fault widths (double the spacing between the entry and impact events) under different speed conditions, but the method of separate treatment is somewhat better and is thus recommended.

Sawalhi, N.; Randall, R. B.

2011-04-01

212

Analysis of suspension and heat transfer characteristics of Al 2O 3 nanofluids prepared through ultrasonic vibration  

Microsoft Academic Search

Nanofluids that contain nanoparticles with excellent heat transfer characteristics dispersed in a continuous liquid phase are expected to exhibit superior thermal and fluid characteristics to those in a single liquid phase primarily because of their much greater collision frequency and larger contact surface between solid nanoparticles and the liquid phase. One of the major challenges in the use of nanofluids

Cherng-Yuan Lin; Jung-Chang Wang; Teng-Chieh Chen

2011-01-01

213

Measuring Fluctuating Pressure Levels and Vibration Response in a Jet Plume  

NASA Technical Reports Server (NTRS)

The characterization of loads due to solid rocket motor plume impingement allows for moreaccurate analyses of components subjected to such an environment. Typically, test verification of predicted loads due to these conditions is widely overlooked or unsuccessful. ATA Engineering, Inc., performed testing during a solid rocket motor firing to obtain acceleration and pressure responses in the hydrodynamic field surrounding the jet plume. The test environment necessitated a robust design to facilitate measurements being made in close proximity to the jet plume. This paper presents the process of designing a test fixture and an instrumentation package that could withstand the solid rocket plume environment and protect the required instrumentation.

Osterholt, Douglas J.; Knox, Douglas M.

2011-01-01

214

Responsibility attitudes and interpretations are characteristic of obsessive compulsive disorder  

Microsoft Academic Search

The cognitive–behavioural theory of Obsessive Compulsive Disorder (OCD) proposes that a key factor influencing obsessional behaviour is the way in which the intrusive cognitions are interpreted. The present paper reports an investigation of links between clinical symptoms (of anxiety, depression and obsessionality) and responsibility beliefs. These beliefs include not only measures of general responsibility attitudes (assumptions) but also more specific

P. M. Salkovskis; A. L. Wroe; A. Gledhill; N. Morrison; E. Forrester; C. Richards; M Reynolds; S Thorpe

2000-01-01

215

Experimental studies of effects of tilt and structural asymmetry on vibration characteristics of thin-wall circular cylinders partly filled with liquid  

NASA Technical Reports Server (NTRS)

The effects of tilt and structural asymmetry on the vibration characteristics of partly liquid-filled thin-wall cylinders were experimentally studied. It was found that tilting the longitudinal axis of a partly filled axisymmetric cylinder from the vertical could markedly reduce its resonant frequencies and change significantly the shape of the circumferential modes. For the minimum frequency modes, vibratory motion occurred only on that side of the cylinder where the liquid was deepest. An empirical equation was derived that gives the equivalent liquid depth of an untilted cylinder having the same minimum resonant frequency as a tilted, partly filled cylinder. Circumferential mode shapes of an untilted asymmetric cylinder were similar to those of the tilted, partly filled axisymmetric cylinder. Vibratory motion in the minimum frequency modes occurred in most instances only on the side of minimum thickness. Correlation between test data and results from a reformulated NASTRAN hydroelastic analysis was excellent.

Herr, R. W.

1978-01-01

216

Vibration isolation of automotive vehicle engine using periodic mounting systems  

NASA Astrophysics Data System (ADS)

Customer awareness and sensitivity to noise and vibration levels have been raised through increasing television advertisement, in which the vehicle noise and vibration performance is used as the main market differentiation. This awareness has caused the transportation industry to regard noise and vibration as important criteria for improving market shares. One industry that tends to be in the forefront of the technology to reduce the levels of noise and vibration is the automobile industry. Hence, it is of practical interest to reduce the vibrations induced structural responses. The automotive vehicle engine is the main source of mechanical vibrations of automobiles. The engine is vulnerable to the dynamic action caused by engine disturbance force in various speed ranges. The vibrations of the automotive vehicle engines may cause structural failure, malfunction of other parts, or discomfort to passengers because of high level noise and vibrations. The mounts of the engines act as the transmission paths of the vibrations transmitted from the excitation sources to the body of the vehicle and passengers. Therefore, proper design and control of these mounts are essential to the attenuation of the vibration of platform structures. To improve vibration resistant capacities of engine mounting systems, vibration control techniques may be used. For instance, some passive and semi-active dissipation devices may be installed at mounts to enhance vibration energy absorbing capacity. In the proposed study, a radically different concept is presented whereby periodic mounts are considered because these mounts exhibit unique dynamic characteristics that make them act as mechanical filters for wave propagation. As a result, waves can propagate along the periodic mounts only within specific frequency bands called the "Pass Bands" and wave propagation is completely blocked within other frequency bands called the "Stop Bands". The experimental arrangements, including the design of mounting systems with plain and periodic mounts will be studied first. The dynamic characteristics of such systems will be obtained experimentally in both cases. The tests will be then carried out to study the performance characteristics of periodic mounts with geometrical and/or material periodicity. The effectiveness of the periodicity on the vibration levels of mounting systems will be demonstrated theoretically and experimentally. Finally, the experimental results will be compared with the theoretical predictions.

Asiri, S.

2005-05-01

217

Cosine response characteristics of radiometric and photometric sensors  

NASA Astrophysics Data System (ADS)

Global and diffuse irradiance and illuminance are measured with instruments that are assumed to have true cosine responses. It is known, largely from reports with a limited distribution or by word of mouth, that no instrument is perfect in this regard. This paper reports on measurements of cosine responses for several instrument types and manufacture familiar to the solar radiation measurement community. The measurements were made with an automated cosine response test bench using the same protocol for each instrument. The cosine bench measures with variable angular resolution as fine as 0.25 degrees. The automated rotation is in one plane. A manual rotation allows measurements for other azimuths.

Michalsky, J. J.; Harrison, L. C.; Berkheiser, W. E., III

218

Short latency responses in the averaged electro-oculogram elicited by vibrational impulse stimuli applied to the skull: could they reflect vestibulo-ocular reflex function?  

PubMed Central

Objectives: To investigate whether vibrational impulse stimuli applied to the skull can be used to evoke the vestibulo-ocular reflex (VOR) and detect vestibular lesions. Methods: Twenty four patients with unilateral vestibular loss (UVD), five with bilateral vestibular loss, two with ocular palsies, and 10 healthy subjects participated. Vibrations of the skull were induced with head taps and with a single period of 160 Hz tone burst on the inion, vertex, and the mastoids while the patients viewed a distant target. Several patients were also examined while viewing a near target, with eccentric gaze and in tilted postures. Responses were recorded by EOG. Results: Responses occurred between 5 ms and 20 ms and seemed to be compensatory to the second phase of the sine wave of vibration impulse and were greatly diminished/absent in patients with bilateral VD and ocular palsies. The patients with UVD had asymmetrical responses in the vertical EOG with stimuli applied on the inion and vertex, with enhancement of the response amplitude on the side of vestibular loss and/or diminution on the healthy side. The asymmetry ratios between the healthy subjects and patients with UVD, and among patients with UVD were statistically significant. Some gaze and positional influences could be demonstrated consistent with otolithic reflexes. Conclusion: If the asymmetric responses to skull vibration in UVD result from passive oscillatory movements of the orbital tissues they may reflect the otolith mediated sustained skew torsion. Conversely, if generated by active eye movements, their likely origin is a phasic VOR. PMID:15654037

Jombik, P; Bahyl, V

2005-01-01

219

Static and dynamic response of a photovoltaic characteristics simulator  

Microsoft Academic Search

In this paper a simulator of photovoltaic generators with programmable electrical characteristics is presented. The proposed system has the ability to generate the current-voltage curves of photovoltaic modules under any desirable insolation and temperature conditions. The system is also capable of integrating any maximum power point tracking algorithm under a unified control. The simulatorpsilas aim is the introduction of a

Anastasios Ch. Nanakos; Emmanuel C. Tatakis

2008-01-01

220

Genetically engineered protein in hydrogels tailors stimuli-responsive characteristics  

NASA Astrophysics Data System (ADS)

Certain proteins undergo a substantial conformational change in response to a given stimulus. This conformational change can manifest in different manners and result in an actuation, that is, catalytic or signalling event, movement, interaction with other proteins, and so on. In all cases, the sensing-actuation process of proteins is initiated by a recognition event that translates into a mechanical action. Thus, proteins are ideal components for designing new nanomaterials that are intelligent and can perform desired mechanical actions in response to target stimuli. A number of approaches have been undertaken to mimic nature's sensing-actuating process. We now report a new hybrid material that integrates genetically engineered proteins within hydrogels capable of producing a stimulus-responsive action mechanism. The mechanical effect is a result of an induced conformational change and binding affinities of the protein in response to a stimulus. The stimuli-responsive hydrogel exhibits three specific swelling stages in response to various ligands offering additional fine-tuned control over a conventional two-stage swelling hydrogel. The newly prepared material was used in the sensing, and subsequent gating and transport of biomolecules across a polymer network, demonstrating its potential application in microfluidics and miniaturized drug-delivery systems.

Ehrick, Jason D.; Deo, Sapna K.; Browning, Tyler W.; Bachas, Leonidas G.; Madou, Marc J.; Daunert, Sylvia

2005-04-01

221

Ab initio determination of geometries and vibrational characteristics of building blocks of organic super-conductors: TTF and its derivatives.  

PubMed

Molecular behavior of the building block {[2-(1,3-dithiole-2-ylidene)-1,3-dithiole] ? tetrathiafulvalene (TTF)} of organic superconductors have been investigated along with its three derivatives, namely, {[2-(1,3-dioxole-2-ylidene)-1,3-dioxole] ? tetraoxafulvalene (TOF)}; [2,2]-bi -[[1,3] oxathiolylidene] ? Der I and 2-(3H-Furan-2-ylidene)-[1,3] oxathiole ? Der II. The properties of the molecules such as molecular geometries, frontier MOs and vibrational spectra have been investigated by using DFT method at the B3LYP level employing 6-311++G(d,p) basis set. The geometrical parameters and atomic charges on various atomic sites of the TTF, TOF, Ders I and II suggest extended conjugation in these systems. The present calculations lead to the reassignments for of some of the fundamentals and new interpretations for some of the observed IR and Raman frequencies. One of the two modes involved in the Fermi resonance giving rise to the doublet 1555 and 1564 cm(-1) needed to be revised and another doublet 3083 and 3108 cm(-1) could be interpreted as a Fermi resonance doublet. Out of the two ?(C = C) modes under the a(1) species, the lower frequency mode is assigned to the ?(C = C) of the ring and the higher one to the ?(C = C) of the central C = C bond contrary to the assignment reported in literature. The conducting properties of these molecules depend mainly on this mode. PMID:23040970

Rani, P; Yadav, R A

2012-12-01

222

Transient response characteristics of test chamber Mach number  

NASA Technical Reports Server (NTRS)

The transient dynamic characteristics of a test chamber Mach number was established for a disturbance initiated in the test chamber. An approximate linear expression was given, showing that the change in the Mach number is linearly proportional to the algebraic sum of the static pressure change in the test chamber and the stagnation pressure change. The static pressure change is the dominating factor. The two pressure changes were also calculated for small Mach number variations, and these results were applied to instrumentation requirements.

Tcheng, P.

1976-01-01

223

Attitudes towards corporate social responsibility and perceived importance of social responsibility information characteristics in a decision context  

Microsoft Academic Search

This study addressed the questions of perceived importance of social responsibility information (SRI) characteristics in a decision context, as well as the attitudes of institutional investors toward social responsibility involvement. The results showed that SRI presently disclosed in company annual reports did not have any significant impact on institutional investors' decisions. However, if SRI were presented in quantified, financial form,

Hai Yap Teoh; Godwin Y Shiu

1990-01-01

224

Vibration isolation via a scissor-like structured platform  

NASA Astrophysics Data System (ADS)

More and more attentions are attracted to the analysis and design of nonlinear vibration control/isolation systems for better isolation performance. In this study, an isolation platform with n-layer scissor-like truss structure is investigated to explore novel design of passive/semi-active/active vibration control/isolation systems and to exploit potential nonlinear benefits in vibration suppression. Due to the special scissor-like structure, the dynamic response of the platform has inherent nonlinearities both in equivalent damping and stiffness characteristics (although only linear components are applied), and demonstrates good loading capacity and excellent equilibrium stability. With the mathematical modeling and analysis of the equivalent stiffness and damping of the system, it is shown that: (a) the structural nonlinearity in the system is very helpful in vibration isolation, (b) both equivalent stiffness and damping characteristics are nonlinear and could be designed/adjusted to a desired nonlinearity by tuning structural parameters, and (c) superior vibration isolation performances (e.g., quasi-zero stiffness characteristics etc.) can be achieved with different structural parameters. This scissor-like truss structure can potentially be employed in different engineering practices for much better vibration isolation or control.

Sun, Xiuting; Jing, Xingjian; Xu, Jian; Cheng, Li

2014-04-01

225

Ab initio determination of geometries and vibrational characteristics of building blocks of organic super-conductors: TTF and its derivatives  

NASA Astrophysics Data System (ADS)

Molecular behavior of the building block {[2-(1,3-dithiole-2-ylidene)-1,3-dithiole] tbnd tetrathiafulvalene (TTF)} of organic superconductors have been investigated along with its three derivatives, namely, {[2-(1,3-dioxole-2-ylidene)-1,3-dioxole]tbnd tetraoxafulvalene (TOF)}; [2,2]-bi -[[1,3] oxathiolylidene]tbnd Der I and 2-(3H-Furan-2-ylidene)-[1,3] oxathioletbnd Der II. The properties of the molecules such as molecular geometries, frontier MOs and vibrational spectra have been investigated by using DFT method at the B3LYP level employing 6-311++G(d,p) basis set. The geometrical parameters and atomic charges on various atomic sites of the TTF, TOF, Ders I and II suggest extended conjugation in these systems. The present calculations lead to the reassignments for of some of the fundamentals and new interpretations for some of the observed IR and Raman frequencies. One of the two modes involved in the Fermi resonance giving rise to the doublet 1555 and 1564 cm-1 needed to be revised and another doublet 3083 and 3108 cm-1 could be interpreted as a Fermi resonance doublet. Out of the two ?(Cdbnd C) modes under the a1 species, the lower frequency mode is assigned to the ?(Cdbnd C) of the ring and the higher one to the ?(Cdbnd C) of the central Cdbnd C bond contrary to the assignment reported in literature. The conducting properties of these molecules depend mainly on this mode.

Rani, P.; Yadav, R. A.

2012-12-01

226

Vibration Characteristics Determined for Stainless Steel Sandwich Panels With a Metal Foam Core for Lightweight Fan Blade Design  

NASA Technical Reports Server (NTRS)

The goal of this project at the NASA Glenn Research Center is to provide fan materials that are safer, weigh less, and cost less than the currently used titanium alloy or polymer matrix composite fans. The proposed material system is a sandwich fan construction made up of thin solid face sheets and a lightweight metal foam core. The stiffness of the sandwich structure is increased by separating the two face sheets by the foam layer. The resulting structure has a high stiffness and lighter weight in comparison to the solid facesheet material alone. The face sheets carry the applied in-plane and bending loads (ref. 1). The metal foam core must resist the transverse shear and transverse normal loads, as well as keep the facings supported and working as a single unit. Metal foams have ranges of mechanical properties, such as light weight, impact resistance, and vibration suppression (ref. 2), which makes them more suitable for use in lightweight fan structures. Metal foams have been available for decades (refs. 3 and 4), but the difficulties in the original processes and high costs have prevented their widespread use. However, advances in production techniques and cost reduction have created a new interest in this class of materials (ref. 5). The material chosen for the face sheet and the metal foam for this study was the aerospace-grade stainless steel 17-4PH. This steel was chosen because of its attractive mechanical properties and the ease with which it can be made through the powder metallurgy process (ref. 6). The advantages of a metal foam core, in comparison to a typical honeycomb core, are material isotropy and the ease of forming complex geometries, such as fan blades. A section of a 17-4PH sandwich structure is shown in the following photograph. Part of process of designing any blade is to determine the natural frequencies of the particular blade shape. A designer needs to predict the resonance frequencies of a new blade design to properly identify a useful operating range. Operating a blade at or near the resonance frequencies leads to high-cycle fatigue, which ultimately limits the blade's durability and life. So the aim of this study is to determine the variation of the resonance frequencies for an idealized sandwich blade as a function of its face-sheet thickness, core thickness, and foam density. The finite element method is used to determine the natural frequencies for an idealized rectangular sandwich blade. The proven Lanczos method (ref. 7) is used in the study to extract the natural frequency.

Ghosn, Louis J.; Min, James B.; Raj, Sai V.; Lerch, Bradley A.; Holland, Frederic A., Jr.

2004-01-01

227

Characteristic neurobiological patterns differentiate paternal responsiveness in two Peromyscus species.  

PubMed

Rodent paternal models provide unique opportunities to investigate the emergence of affiliative social behavior in mammals. Using biparental and uniparental Peromyscus species (californicus and maniculatus, respectively) we assessed paternal responsiveness by exposing males to biological offspring, unrelated conspecific pups, or familiar brothers following a 24-hour separation. The putative paternal circuit we investigated included brain areas involved in fear/anxiety [cingulate cortex (Cg), medial amygdala (MeA), paraventricular nucleus of the hypothalamus (PVN), and lateral septum (LS)], parental motivation [medial preoptic area (MPOA)], learning/behavioral plasticity (hippocampus), olfaction [pyriform cortex (PC)], and social rewards (nucleus accumbens). Paternal experience in californicus males reduced fos immunoreactivity (ir) in several fear/anxiety areas; additionally, all californicus groups exhibited decreased fos-ir in the PC. Enhanced arginine vasopressin (AVP) and oxytocin (OT)-ir cell bodies and fibers, as well as increased neuronal restructuring in the hippocampus, were also observed in californicus mice. Multidimensional scaling analyses revealed distinct brain activation profiles differentiating californicus biological fathers, pup-exposed virgins, and pup-naïve virgins. Specifically, associations among MPOA fos, CA1 fos, dentate gyrus GFAP, CA2 nestin-, and PVN OT-ir characterized biological fathers; LS fos-, Cg fos-, and AVP-ir characterized pup-exposed virgins, and PC-, PVN-, and MeA fos-ir characterized pup-naïve virgins. Thus, whereas fear/anxiety areas characterized pup-naïve males, neurobiological factors involved in more diverse functions such as learning, motivation, and nurturing responses characterized fatherhood in biparental californicus mice. Less distinct paternal-dependent activation patterns were observed in uniparental maniculatus mice. These data suggest that dual neurobiological circuits, leading to the inhibition of social-dependent anxiety as well as the activation of affiliative responses, characterize the transition from nonpaternal to paternal status in californicus mice. PMID:21546770

Lambert, Kelly G; Franssen, Catherine L; Bardi, Massimo; Hampton, Joseph E; Hainley, Leslie; Karsner, Stephanie; Tu, Eddie B; Hyer, Molly M; Crockett, Ashly; Baranova, Anya; Ferguson, Tajh; Ferguson, Tenaj; Kinsley, Craig H

2011-01-01

228

Response Characteristics of High-Performance Photorefractive Liquid Crystals  

NASA Astrophysics Data System (ADS)

The time response of high-performance photorefractivity in a thick-grating regime was characterized in high- (H-LC) and low-molar-mass liquid crystal (L-LC) mixtures (HL-LCMs) doped with fullerene. A high two-beam coupling gain coefficient of over 250 cm-1 was achieved at a low applied dc field of 0.16 V/µm. The photorefractive grating formation time was varied between 0.12 and 0.5 s, which strongly depended on the two-beam power ratio, the two beam intensities and the applied dc field.

Ono, Hiroshi; Kawatsuki, Nobuhiro

1999-02-01

229

Roman Catholic beliefs produce characteristic neural responses to moral dilemmas.  

PubMed

This study provides exploratory evidence about how behavioral and neural responses to standard moral dilemmas are influenced by religious belief. Eleven Catholics and 13 Atheists (all female) judged 48 moral dilemmas. Differential neural activity between the two groups was found in precuneus and in prefrontal, frontal and temporal regions. Furthermore, a double dissociation showed that Catholics recruited different areas for deontological (precuneus; temporoparietal junction) and utilitarian moral judgments [dorsolateral prefrontal cortex (DLPFC); temporal poles], whereas Atheists did not (superior parietal gyrus for both types of judgment). Finally, we tested how both groups responded to personal and impersonal moral dilemmas: Catholics showed enhanced activity in DLPFC and posterior cingulate cortex during utilitarian moral judgments to impersonal moral dilemmas and enhanced responses in anterior cingulate cortex and superior temporal sulcus during deontological moral judgments to personal moral dilemmas. Our results indicate that moral judgment can be influenced by an acquired set of norms and conventions transmitted through religious indoctrination and practice. Catholic individuals may hold enhanced awareness of the incommensurability between two unequivocal doctrines of the Catholic belief set, triggered explicitly in a moral dilemma: help and care in all circumstances-but thou shalt not kill. PMID:23160812

Christensen, Julia F; Flexas, Albert; de Miguel, Pedro; Cela-Conde, Camilo J; Munar, Enric

2014-02-01

230

An active head-neck model in whole-body vibration: vibration magnitude and softening.  

PubMed

An active head-neck model is introduced in this work to predict human-dynamic response to different vibration magnitudes during fore-aft whole-body vibration. The proposed model is a rigid-link dynamic system augmented with passive spring-damper tissue-like elements and additional active dampers that resemble the active part of the muscles. The additional active dampers are functions of the input displacement, velocity, and acceleration and are based on active control theories and a kd-tree data-searching scheme. Five human subjects exposed to random fore-aft vibration with frequency content of 0.5-10 Hz were tested under different vibration with magnitudes of 0.46 m/s(2), 1.32 m/s(2), and 1.66 m/s(2) rms. The results showed that the proposed model was able to reasonably capture the softening characteristics of the human head-neck response during fore-aft whole-body vibration of different magnitudes. PMID:22336196

Rahmatalla, Salam; Liu, Ye

2012-04-01

231

Effects of a Dynamic Warm-Up, Static Stretching or Static Stretching with Tendon Vibration on Vertical Jump Performance and EMG Responses.  

PubMed

The purpose of this study was to investigate the short-term effects of static stretching, with vibration given directly over Achilles tendon, on electro-myographic (EMG) responses and vertical jump (VJ) performances. Fifteen male, college athletes voluntarily participated in this study (n=15; age: 22±4 years old; body height: 181±10 cm; body mass: 74±11 kg). All stages were completed within 90 minutes for each participant. Tendon vibration bouts lasted 30 seconds at 50 Hz for each volunteer. EMG analysis for peripheral silent period, H-reflex, H-reflex threshold, T-reflex and H/M ratio were completed for each experimental phases. EMG data were obtained from the soleus muscle in response to electro stimulation on the popliteal post tibial nerve. As expected, the dynamic warm-up (DW) increased VJ performances (p=0.004). Increased VJ performances after the DW were not statistically substantiated by the EMG findings. In addition, EMG results did not indicate that either static stretching (SS) or tendon vibration combined with static stretching (TVSS) had any detrimental or facilitation effect on vertical jump performances. In conclusion, using TVSS does not seem to facilitate warm-up effects before explosive performance. PMID:24511340

Yapicioglu, Bulent; Colakoglu, Muzaffer; Colakoglu, Zafer; Gulluoglu, Halil; Bademkiran, Fikret; Ozkaya, Ozgur

2013-12-18

232

Free in-plane vibration of circular arches.  

NASA Technical Reports Server (NTRS)

Numerical data are presented for the natural frequencies and modes of vibration of hinged and fixed, uniform, circular arches vibrating in their own plane, and the effects of the various parameters affecting the response are analyzed. It is shown that the vibrational modes may be almost purely flexural, or almost purely extensional, or the extensional and flexural actions may be strongly coupled. The conditions of occurrence of each type of behavior are defined, and simple approximate formulas are derived; using these formulas, the free vibrational characteristics of arches may be estimated to a satisfactory degree of accuracy for most practical applications. The approach used to derive the approximate formulas may also be applied to arches having other boundary conditions, shapes, or distributions of stiffness and mass.

Veletsos, A. S.; Austin, W. J.; Lopes Pereira, C. A.; Wung, S.-J.

1972-01-01

233

The Person Response Curve: Fit of Individuals to Item Characteristic Curve Models.  

National Technical Information Service (NTIS)

This study investigated a method of determining the fit of individuals to item characteristic curve (ICC) models using the person response curve (PRC). The construction of observed PRCs is based on an individual's proportion correct on test item subsets (...

T. E. Trabin, D. J. Weiss

1979-01-01

234

Response Characteristics of an Aquatic Biomonitor Used for Rapid Toxicity Detection.  

National Technical Information Service (NTIS)

The response characteristics of an aquatic biomonitor that detects toxicity by monitoring changes in bluegill (Lepomis macrochirus Rafinesque) ventiliatory and movement patterns were evaluated in single chemical laboratory studies at concentrations near t...

W. H. VAN DER Schalie, T. R. Shedd, M. W. Widder, L. M. Brennan

2004-01-01

235

Investigation of frequency-response characteristics of engine speed for a typical turbine-propeller engine  

NASA Technical Reports Server (NTRS)

Experimental frequency-response characteristics of engine speed for a typical turbine-propeller engine are presented. These data were obtained by subjecting the engine to sinusoidal variations of fuel flow and propeller-blade-angle inputs. Correlation is made between these experimental data and analytical frequency-response characteristics obtained from a linear differential equation derived from steady-state torque-speed relations.

Taylor, Burt L , III; Oppenheimer, Frank L

1951-01-01

236

A Branched Beam-Based Vibration Energy Harvester  

NASA Astrophysics Data System (ADS)

In this paper, a strategy to utilize a branched beam system to improve the frequency response characteristic of vibration energy harvesting is demonstrated. A basic unit of the device consists of several branch beams with proof mass at their ends and one main cantilever beam with a piezoelectric component at its root and proof mass at its end. The device can utilize the resonance of the branch beams and main beam to generate multiple output voltage peaks, providing a better frequency response characteristic than that of the conventional piezoelectric vibration energy harvester. Multiple branch structure and multiple basic units with similar structures can be connected to generate more output voltage peaks in the frequency response characteristic. Only one piezoelectric component is needed in the device, which makes it competitive in the management of harvested electric energy.

Zhang, Guangcheng; Hu, Junhui

2014-09-01

237

A Branched Beam-Based Vibration Energy Harvester  

NASA Astrophysics Data System (ADS)

In this paper, a strategy to utilize a branched beam system to improve the frequency response characteristic of vibration energy harvesting is demonstrated. A basic unit of the device consists of several branch beams with proof mass at their ends and one main cantilever beam with a piezoelectric component at its root and proof mass at its end. The device can utilize the resonance of the branch beams and main beam to generate multiple output voltage peaks, providing a better frequency response characteristic than that of the conventional piezoelectric vibration energy harvester. Multiple branch structure and multiple basic units with similar structures can be connected to generate more output voltage peaks in the frequency response characteristic. Only one piezoelectric component is needed in the device, which makes it competitive in the management of harvested electric energy.

Zhang, Guangcheng; Hu, Junhui

2014-11-01

238

Plant characteristic estimation using sonar, multispectral reflectance, and electromagnetic response  

NASA Astrophysics Data System (ADS)

Scope and method of study. The goal of this study was to design, test and validate three methods of remotely estimating plant physical and physiological characteristics. A free-space parallel plate electrostatic sensing system operating at medium radio frequency range was used to estimate water content and plant dry biomass. An ultrasound distance sensing system and a multispectral imaging system was used to directly estimate plant height and top view surface area and indirectly estimate plant biomass. NDVI was calculated from the multispectral imaging system data. Combining NDVI with the plant height and top view surface area estimates, a correlation was observed between plant biomass, chlorophyll content and chlorophyll concentration. Findings and conclusions. Plant water content and dry biomass of greenhouse grown spinach were estimated using a free-space electrostatic sensing system (r2 = 0.95). Ultrasonic sensor-based height estimates and top view surface area multispectral image data provided plant biomass estimates in corn and spinach (r 2 = 0.85 and 0.88). Estimates for snap beans were not as convincing (r2 = 0.52). Combining biomass estimates from the height and surface area data obtained by the ultrasonic distance sensor and the multispectral imaging system with NDVI670 calculated from reflectance data from the imaging system provided strong correlations with chlorophyll content in spinach (r 2 = 0.91). This was an improvement from the chlorophyll content estimates using only NDVI670. Correlations with chlorophyll concentration were weak. The strongest correlation was found using the reflectance ratio, NIR/Green (r2 = 0.30).

Jones, Carol L.

239

Good Vibrations  

NSDL National Science Digital Library

This lesson (on pages 15-24 of PDF) explores how sound is caused by vibrating objects. It explains that we hear by feeling vibrations passing through the air. Learners take part in several demonstrations, making those vibrations visible. They put a tuning fork in a shallow pan of water and use it to bounce a ping-pong ball, showing the fact that the tuning fork is vibrating when it's making a sound. There are extensions described involving comb kazoos, rubber band guitars, and putting rice or cereal on top of a drum.

Omsi

2010-01-01

240

Pediatric high speed digital imaging of vocal fold vibration: A normative pilot study of glottal closure and phase closure characteristics  

PubMed Central

Objective The aim of the study is to characterize normal vibratory patterns of both glottal closure and phase closure in the pediatric population with the use of high speed digital imaging. Methods For this prospective study a total of 56 pre-pubertal children, 5–11 years (boys = 28, girls = 28) and 56 adults, 21–45 years (males = 28, females = 28) without known voice problems were examined with the use of a new technology of high speed digital imaging. Recordings were captured at 4000 frames per second for duration of 4.094 seconds at participants’ typical phonation. With semi-automated software, montage analysis of glottal cycles was performed. Three trained experienced raters, rated features of glottal configuration and phase closure from glottal cycle montages. Results Posterior glottal gap was the predominant glottal closure configuration in children (girls = 85%, boys = 68%) with normal voice. Other glottal configurations observed were: anterior gap (girls = 3.6%, boys = 0%), complete closure (girls = 7%, boys = 10%), hour glass (girls = 0%, boys = 11%). Adults with normal voice also demonstrated predominantly higher percentage of posterior glottal gap configuration (females = 75% male = 54%) compared to the configurations of anterior gap (females = 0% male = 7%), complete closure (females = 2% male = 39%), hour glass (females = 3.6% male = 3.6%). A predominantly open phase (51–70% of the glottal cycle) was observed in 86% girls and 71% boys. Compared to children, adult females showed a predominantly balance phased closure 46%, followed by open phase (39%) and predominantly closed phase (14%). Adult males showed a predominantly closed phase (43%), followed by predominantly open phase (39%), followed by a balanced phase (18%). Conclusions This is a first study investigating characteristics of normal vibratory motion in children with high speed digital imaging. Glottal configuration and phase closure for children with normal voices are distinctly different compared to adults. The results suggest that posterior glottal gap and a predominantly open phase of the glottal cycle should be considered as normal glottal configuration in children during modal pitch and loudness. This study provides preliminary information on the vibratory characteristics of children with normal voice. The data presented here may provide the bases for differentiating normal vibratory characteristics from the disordered in the pediatric population. PMID:22445799

Patel, Rita R.; Dixon, Angela; Richmond, AnnaMary; Donohue, Kevin D.

2012-01-01

241

Intra- and inter-molecular hydrogen bonds, conformation and vibrational characteristics of hydrazo-group in 5-nitro-2-(2-phenylhydrazinyl)pyridine and its 3-, 4- or 6-methyl isomers.  

PubMed

Syntheses of 5-nitro-2-(2-phenylhydrazinyl)pyridine (5-nitro-2-phenylhydrazopyridine), 3-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (3-methyl-5-nitro-2-phenylhydrazopyridine), 4-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (4-methyl-5-nitro-2-phenylhydrazopyridine) and 6-methyl-5-nitro-2-(2-phenylhydrazinyl)pyridine (6-methyl-5-nitro-2-phenylhydrazopyridine) have been described. Their IR and Raman spectra have been measured and analyzed in terms of DFT quantum chemical calculations. The 6-311G(2d,2p) basis set with the B3LYP functional has been used to discuss the optimized structure and vibrational spectra. The vibrational characteristics of the hydrazo-bond have been reported with their relation to the inter- and intra-molecular hydrogen bonds formed in the studied systems. The role and influence of substitution position of the methyl chromophore on the structure and vibrational data have been discussed. PMID:23680510

Michalski, J; Kucharska, E; S?siadek, W; Lorenc, J; Hanuza, J

2013-08-01

242

Torsional vibration reduction using passive nonlinear absorbers  

NASA Astrophysics Data System (ADS)

This paper considers the dynamic performance of systems of centrifugal pendulum vibration absorbers that are used to attenuate torsional vibrations in rotating systems. These absorbers, which can be found in certain IC engines and helicopter rotors, consist of movable masses whose centers of mass are kinematically restricted to move along prescribed paths relative to the rotor of interest. The most common choice for absorber paths are simple circles that are slightly mistuned from the desired order, so that undesirable nonlinear behaviors are avoided when the absorbers undergo large amplitude motions. In this work we consider a range of different path types and tunings, with the goal of optimizing performance over a wide operating range. This analytical study relies on a mathematical model of a rotor fitted with N identical, general-path absorbers, and utilizes perturbation techniques to obtain analytical estimates for the response of the rotor and the absorbers. The results are used to select path parameters based on selected performance measures, and the results are verified via simulation studies. It is shown that slightly overtuned cycloidal paths provide excellent vibration reduction characteristics and prevent the occurrence of nonlinear instabilities and vibration localization in the response of the absorbers.

Shaw, Steven W.; Alsuwaiyan, Abdallah

2000-04-01

243

Operating Characteristics of Six Response Distortion Indicators for the Personality Assessment Inventory.  

ERIC Educational Resources Information Center

Characteristics of six different indicators of response distortion on the Personality Assessment Inventory (PAI) (L. Morey, 1991) were evaluated by having 134 college students complete the PAI under positive impression management, malingering, and honest responding conditions. All six indicators could distinguish actual and feigned responses. (SLD)

Morey, Leslie C.; Lanier, V. Whitson

1998-01-01

244

A Patch Density Recommendation based on Convergence Studies for Vehicle Panel Vibration Response resulting from Excitation by a Diffuse Acoustic Field  

NASA Technical Reports Server (NTRS)

Fluid structural interaction problems that estimate panel vibration from an applied pressure field excitation are quite dependent on the spatial correlation of the pressure field. There is a danger of either over estimating a low frequency response or under predicting broad band panel response in the more modally dense bands if the pressure field spatial correlation is not accounted for adequately. Even when the analyst elects to use a fitted function for the spatial correlation an error may be introduced if the choice of patch density is not fine enough to represent the more continuous spatial correlation function throughout the intended frequency range of interest. Both qualitative and quantitative illustrations evaluating the adequacy of different patch density assumptions to approximate the fitted spatial correlation function are provided. The actual response of a typical vehicle panel system is then evaluated in a convergence study where the patch density assumptions are varied over the same finite element model. The convergence study results are presented illustrating the impact resulting from a poor choice of patch density. The fitted correlation function used in this study represents a Diffuse Acoustic Field (DAF) excitation of the panel to produce vibration response.

Smith, Andrew; LaVerde, Bruce; Jones, Douglas; Towner, Robert; Hunt, Ron

2013-01-01

245

Good Vibrations  

NSDL National Science Digital Library

In this activity, learners experiment with their voices and noisemakers to understand the connections between vibrations and the sounds created by those vibrations. This resource includes three quick demonstration activities that can be used independently or as a group to introduce learners to the basic elements of sound.

Omsi

2004-01-01

246

Vibrational Coupling  

SciTech Connect

By homing in on the distribution patterns of electrons around an atom, a team of scientists team with Berkeley Lab's Molecular Foundry showed how certain vibrations from benzene thiol cause electrical charge to "slosh" onto a gold surface (left), while others do not (right). The vibrations that cause this "sloshing" behavior yield a stronger SERS signal.

None

2011-01-01

247

Development of a new fiber-optic acoustic\\/vibration sensor: Principle, sensor performance, applicability to health monitoring and characteristic at elevated temperature  

Microsoft Academic Search

A new fiber-optic vibration sensor has been developed and applied to structural health monitoring. The sensor is based on new finding that frequency of light wave transmitted through a bended optical fiber is shifted by vibration at the bended region. The principle can be explained that Doppler's effect of the light wave which changes its direction in the optical fiber.

Kazuro Kageyama; Hideaki Murayama; Isamu Ohsawa; Makoto Kanai; Tomokazu Motegi; Keiichi Nagata; Yuichi Machijima; Humio Matsumura

2003-01-01

248

Influence of structural parameters on dynamic characteristics and wind-induced buffeting responses of a super-long-span cable-stayed bridge  

NASA Astrophysics Data System (ADS)

A 3D finite element (FE) model for the Sutong cable-stayed bridge (SCB) is established based on ANSYS. The dynamic characteristics of the bridge are analyzed using a subspace iteration method. Based on recorded wind data, the measured spectra expression is presented using the nonlinear least-squares regression method. Turbulent winds at the bridge site are simulated based on the spectral representation method and the FFT technique. The influence of some key structural parameters and measures on the dynamic characteristics of the bridge are investigated. These parameters include dead load intensity, as well as vertical, lateral and torsional stiffness of the steel box girder. In addition, the influence of elastic stiffness of the connection device employed between the towers and the girder on the vibration mode of the steel box girder is investigated. The analysis shows that all of the vertical, lateral and torsional buffeting displacement responses reduce gradually as the dead load intensity increases. The dynamic characteristics and the structural buffeting displacement response of the SCB are only slightly affected by the vertical and torsional stiffness of the steel box girder, and the lateral and torsional buffeting displacement responses reduce gradually as the lateral stiffness increases. These results provide a reference for dynamic analysis and design of super-long-span cable-stayed bridges.

Wang, Hao; Chen, Chunchao; Xing, Chenxi; Li, Aiqun

2014-09-01

249

Force Limited Vibration Testing  

NASA Technical Reports Server (NTRS)

This slide presentation reviews the concept and applications of Force Limited Vibration Testing. The goal of vibration testing of aerospace hardware is to identify problems that would result in flight failures. The commonly used aerospace vibration tests uses artificially high shaker forces and responses at the resonance frequencies of the test item. It has become common to limit the acceleration responses in the test to those predicted for the flight. This requires an analysis of the acceleration response, and requires placing accelerometers on the test item. With the advent of piezoelectric gages it has become possible to improve vibration testing. The basic equations have are reviewed. Force limits are analogous and complementary to the acceleration specifications used in conventional vibration testing. Just as the acceleration specification is the frequency spectrum envelope of the in-flight acceleration at the interface between the test item and flight mounting structure, the force limit is the envelope of the in-flight force at the interface . In force limited vibration tests, both the acceleration and force specifications are needed, and the force specification is generally based on and proportional to the acceleration specification. Therefore, force limiting does not compensate for errors in the development of the acceleration specification, e.g., too much conservatism or the lack thereof. These errors will carry over into the force specification. Since in-flight vibratory force data are scarce, force limits are often derived from coupled system analyses and impedance information obtained from measurements or finite element models (FEM). Fortunately, data on the interface forces between systems and components are now available from system acoustic and vibration tests of development test models and from a few flight experiments. Semi-empirical methods of predicting force limits are currently being developed on the basis of the limited flight and system test data. A simple two degree of freedom system is shown and the governing equations for basic force limiting results for this system are reviewed. The design and results of the shuttle vibration forces (SVF) experiments are reviewed. The Advanced Composition Explorer (ACE) also was used to validate force limiting. Test instrumentation and supporting equipment are reviewed including piezo-electric force transducers, signal processing and conditioning systems, test fixtures, and vibration controller systems. Several examples of force limited vibration testing are presented with some results.

Scharton, Terry; Chang, Kurng Y.

2005-01-01

250

An investigation of institutional characteristics associated with response rates in mail surveys of community hospitals.  

PubMed

This paper describes the nature and strength of the relationship between six institutional characteristics of U.S. community hospitals and the rates of response of these hospitals to a nationwide survey conducted by the American Hospital Association (AHA). Furthermore, it demonstrates how one can calculate accurately the relative probability of response of hospitals with various combinations of these characteristics. The six characteristics studied were bed size, teaching status, AHA membership status, location within or without a Standard Metropolitan Statistical Area, investor or other form of ownership, and control by State or local government or by another type of organization.The six characteristics were treated as dichotomous variables throughout most of the analysis. Odds ratios were calculated for each variable as a preliminary measure of the strength of its association with response.The effects of confounding on those odds ratios were controlled for by multiple logistic regression, which estimates the probability of response of hospitals with given characteristics. A logistic odds ratio was calculated for each variable to estimate the independent effect that specified values had on the odds of responding. All variables except status as a teaching or nonteaching hospital were shown to have a significant relationship to response.Hospitals were divided into classes according to probability of response, and the probability of response was compared with actual rates of response in the survey. Both increase at equal rates. Similar results were obtained by applying this method to two other, dissimilar, surveys.This method is generalizable to other surveys and should prove useful to researchers wishing to increase response rates in their surveys of hospitals. PMID:7208796

Mullner, R; Levy, P S; Matthews, D; Byre, C S

1981-01-01

251

A global statistical model based approach for vibration response-only damage detection under various temperatures: A proof-of-concept study  

NASA Astrophysics Data System (ADS)

The statistical damage detection in a composite beam structure operating under different temperatures is considered based on vibration response-only signals. For this purpose a novel stochastic global model approach is introduced based upon statistical hypothesis testing and identified Functionally Pooled models capable of describing the temperature-dependent dynamics. Two versions of the approach that use either modal or discrete-time model parameters are postulated. This is a proof-of-concept study in which the effectiveness of the approach is confirmed via laboratory experiments. Comparisons with alternative methods attempting removal of the temperature effects from the damage-sensitive features are also made.

Hios, J. D.; Fassois, S. D.

2014-12-01

252

Time-domain parameter identification of aeroelastic loads by forced-vibration method for response of flexible structures subject to transient wind  

NASA Astrophysics Data System (ADS)

Slender structures representing civil, mechanical and aerospace systems such as long-span bridges, high-rise buildings, stay cables, power-line cables, high light mast poles, crane-booms and aircraft wings could experience vortex-induced and buffeting excitations below their design wind speeds and divergent self-excited oscillations (flutter) beyond a critical wind speed because these are flexible. Traditional linear aerodynamic theories that are routinely applied for their response prediction are not valid in the galloping, or near-flutter regime, where large-amplitude vibrations could occur and during non-stationary and transient wind excitations that occur, for example, during hurricanes, thunderstorms and gust fronts. The linear aerodynamic load formulation for lift, drag and moment are expressed in terms of aerodynamic functions in frequency domain that are valid for straight-line winds which are stationary or weakly-stationary. Application of the frequency domain formulation is restricted from use in the nonlinear and transient domain because these are valid for linear models and stationary wind. The time-domain aerodynamic force formulations are suitable for finite element modeling, feedback-dependent structural control mechanism, fatigue-life prediction, and above all modeling of transient structural behavior during non-stationary wind phenomena. This has motivated the developing of time-domain models of aerodynamic loads that are in parallel to the existing frequency-dependent models. Parameters defining these time-domain models can be now extracted from wind tunnel tests, for example, the Rational Function Coefficients defining the self-excited wind loads can be extracted using section model tests using the free vibration technique. However, the free vibration method has some limitations because it is difficult to apply at high wind speeds, in turbulent wind environment, or on unstable cross sections with negative aerodynamic damping. In the current research, new algorithms were developed based on forced vibration technique for direct extraction of the Rational Functions. The first of the two algorithms developed uses the two angular phase lag values between the measured vertical or torsional displacement and the measured aerodynamic lift and moment produced on the section model subject to forced vibration to identify the Rational Functions. This algorithm uses two separate one-degree-of-freedom tests (vertical or torsional) to identify all the four Rational Functions or corresponding Rational Function Coefficients for a two degrees-of-freedom (DOF) vertical-torsional vibration model. It was applied to a streamlined section model and the results compared well with those obtained from earlier free vibration experiment. The second algorithm that was developed is based on direct least squares method. It uses all the data points of displacements and aerodynamic lift and moment instead of phase lag values for more accurate estimates. This algorithm can be used for one-, two- and three-degree-of-freedom motions. A two-degree-of-freedom forced vibration system was developed and the algorithm was shown to work well for both streamlined and bluff section models. The uniqueness of the second algorithms lies in the fact that it requires testing the model at only two wind speeds for extraction of all four Rational Functions. The Rational Function Coefficients that were extracted for a streamlined section model using the two-DOF Least Squares algorithm were validated in a separate wind tunnel by testing a larger scaled model subject to straight-line, gusty and boundary-layer wind.

Cao, Bochao

253

The response characteristics of GafChromic dosimetry media to 60Co gamma rays  

Microsoft Academic Search

The dosimetric characteristics of GafChromic Dosimetry Media after being irradiated by 60Co gamma rays have been studied and the dependence of the radiation-induced absorbance on the temperature during irradiated and during reading and the postirradiated effect are reported. The dose-response characteristics of the films to 60Co gamma rays at the reading wavelengths of 400 and 580 nm have been analyzed,

Li Zhongying; Peng Shouyong; Chen Yundong; Zhang Lu

1995-01-01

254

Integrated tuned vibration absorbers: a theoretical study.  

PubMed

This article presents a simulation study on two integrated tuned vibration absorbers (TVAs) designed to control the global flexural vibration of lightly damped thin structures subject to broad frequency band disturbances. The first one consists of a single axial switching TVA composed by a seismic mass mounted on variable axial spring and damper elements so that the characteristic damping and natural frequency of the absorber can be switched iteratively to control the resonant response of three flexural modes of the hosting structure. The second one consists of a single three-axes TVA composed by a seismic mass mounted on axial and rotational springs and dampers, which are arranged in such a way that the suspended mass is characterized by uncoupled heave and pitch-rolling vibrations. In this case the three damping and natural frequency parameters of the absorber are tuned separately to control three flexural modes of the hosting structure. The simulation study shows that the proposed single-unit absorbers produce, respectively, 5.3 and 8.7?dB reductions of the global flexural vibration of a rectangular plate between 20 and 120?Hz. PMID:24180774

Gardonio, Paolo; Zilletti, Michele

2013-11-01

255

Vibration generators  

SciTech Connect

Apparatus for generating vibrations in a medium, such as the ground, comprises a first member which contacts the medium, means , preferably electromagnetic, which includes two relatively movable members for generating vibrations in the apparatus and means operatively connecting the said two members to said first member such that the relatively amplitudes of the movements of said three members can be adjusted to match the impedances of the apparatus and the medium.

Lerwill, W.E.

1980-09-16

256

Vibration sensors  

NASA Astrophysics Data System (ADS)

Today, vibration sensors with low and medium sensitivities are in great demand. Their applications include robotics, navigation, machine vibration monitoring, isolation of precision equipment & activation of safety systems e.g. airbags in automobiles. Vibration sensors have been developed at SSPL, using silicon micromachining to sense vibrations in a system in the 30 - 200 Hz frequency band. The sensing element in the silicon vibration sensor is a seismic mass suspended by thin silicon hinges mounted on a metallized glass plate forming a parallel plate capacitor. The movement of the seismic mass along the vertical axis is monitored to sense vibrations. This is obtained by measuring the change in capacitance. The movable plate of the parallel plate capacitor is formed by a block connected to a surrounding frame by four cantilever beams located on sides or corners of the seismic mass. This element is fabricated by silicon micromachining. Several sensors in the chip sizes 1.6 cm x 1.6 cm, 1 cm x 1 cm and 0.7 cm x 0.7 cm have been fabricated. Work done on these sensors, techniques used in processing and silicon to glass bonding are presented in the paper. Performance evaluation of these sensors is also discussed.

Gupta, Amita; Singh, Ranvir; Ahmad, Amir; Kumar, Mahesh

2003-10-01

257

Female gray treefrogs, Hyla versicolor, are responsive to visual stimuli but unselective of stimulus characteristics.  

PubMed

The visual ecology of nocturnal anurans is poorly understood, but there is growing evidence that vision plays a role in important behaviors such as mate choice. While several recent studies have demonstrated that females are responsive to visual cues when selecting mates, the forces responsible for these preferences are unknown. We investigated the responsiveness of female gray treefrogs, Hyla versicolor, to video playbacks of calling conspecific males in which we varied attributes of the vocal sac, a conspicuous visual characteristic of calling males and a target of female choice in other species. Females responded surprisingly strongly to the video playbacks, but did so indiscriminately with respect to variation in vocal sac characteristics. We followed up on these results with a series of additional tests that examined female responses to abstract stimuli. Females continued to respond to such stimuli, leading us to conclude that their behavior was related to a generalized phototactic response. Because of this, we were unable to make conclusions regarding female preferences for vocal sac characteristics. Nonetheless, our results are significant in two respects. First, we illustrate that despite much effort into improving video playback methodologies, challenges remain, and we offer our experimental design as a method to ensure that appropriate conclusions can be drawn from such studies. Second, we argue that the female phototactic response has potentially significant behavioral implications and in general the consequences of anuran visual preferences deserve further investigation. PMID:25013111

Reichert, Michael S; Galante, Holland; Höbel, Gerlinde

2014-09-15

258

A Gaussian model for predicting the effect of unsteady windspeed on the vortex-induced vibration response of structural members  

SciTech Connect

In a previous study the authors have shown that the expected duration of visit by the windspeed to the critical velocity interval of a structural member is an important time scale in determining the ultimate fatigue damage of the member due to vortex-induced vibration in naturally time varying winds. In this paper, a Gaussian windspeed assumption is introduced in which the expected duration of visit can be expressed explicitly in terms of simple wind statistics. This assumption is verified with high sampling rate maritime wind data. The wind statistics necessary for calculation of the expected duration of visit are extracted from the raw wind data.

Fei, C.Y.; Vandiver, J.K. [Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Ocean Engineering

1995-12-31

259

Measurement and analysis of the frequency response characteristics of Lightning Location System  

Microsoft Academic Search

Experts from Wuhan high voltage research institute have developed a lightning location system. Experimental studies on the frequency response characteristics of the magnetic field measuring loop were carried out at a thunder detection station, and results are presented in this paper. In addition, theoretical analysis and numerical analysis are presented, and suggestions of improvement for the magnetic field measuring loop

Zhaonan Luo; Xiang Cui; Zhibin Zhao; Lei Liu

2008-01-01

260

Utility of MMPI-2 Indicators of Response Distortion: Receiver Operating Characteristic Analysis.  

ERIC Educational Resources Information Center

Receiver operating characteristic (ROC) analysis was used to evaluate 11 Minnesota Multiphasic Personality Inventory-2 (MMPI-2) indicators of response distortion using 343 college students, some of whom simulated malingering or defensive responding, 181 forensic psychiatric patients, and 95 other psychiatric patients. Results show the usefulness…

Nicholson, Robert A.; Mouton, Glenn J.; Bagby, R. Michael; Buis, Tom; Peterson, Stephanie A.; Buigas, Rudy A.

1997-01-01

261

Preference for Anonymous Classroom Participation: Linking Student Characteristics and Reactions to Electronic Response Systems  

ERIC Educational Resources Information Center

Electronic response systems (ERS) are a means to foster class participation by students who are reluctant to participate in class. In this study, we identify individual characteristics that relate to students' preference for anonymous classroom participation, and we also examine the extent to which preference for anonymity is related to their…

Latham, Alyson; Hill, N. Sharon

2014-01-01

262

The Association between SAT Prompt Characteristics, Response Features, and Essay Scores  

ERIC Educational Resources Information Center

This study investigated the relationship of prompt characteristics and response features with essay scores on the SAT Reasoning Test. A sample of essays was coded on a variety of features regarding their length and content. Analyses included descriptive statistics and computation of effect sizes, correlations between essay features and scores, and…

Kobrin, Jennifer L.; Deng, Hui; Shaw, Emily J.

2011-01-01

263

Relationships of Examinee Pair Characteristics and Item Response Similarity. ACT Research Report Series, 2012 (8)  

ERIC Educational Resources Information Center

Detecting unusual similarity in the item responses of a pair of examinees usually conditions on the pair's overall test performance (e.g., raw scores). Doing this, however, often requires assumptions about the invariance of other examinee pair characteristics. In this study, we examined the appropriateness of such assumptions about selected…

Allen, Jeff

2012-01-01

264

A technique for removing platform vibration noise from a pulsed ladar vibration sensor  

Microsoft Academic Search

A technique has been developed for removing platform-induced vibration noise from a pulsed ladar vibration sensor. Deriving the vibrational characteristics of the platform is accomplished by simulating ambient atmospheric aerosols as a stationary reference target. Using a pulsed coherent detection ladar, the instantaneous Doppler frequency shifts from both aerosols and a distant hard target are measured and recorded, while the

T. A. Sturm; R. Richmond; B. D. Duncan

1995-01-01

265

Two spatio-temporal filters in human vision. 1. Temporal and spatial frequency response characteristics.  

PubMed

We have studied visual detection of a circular target moving across a spatially and/or temporally modulated background. Illumination, It, for threshold detection of the target has been measured as a function of background modulation frequency and changes in It associated with background modulation provide a means of determining the frequency response characteristics of visual channels. Temporal frequency responses obtained with temporally modulated, spatially uniform backgrounds have pass-band characteristics and the temporal frequency for peak response increases with increase in mean background illumination. These temporal frequency responses resemble those of the de Lange (1954) filter, but the latter incorporates the incremental thresholds for steady backgrounds. The amplitude of this temporal response saturates at low (approximately 40%) background modulation, decreases to zero as the target velocity falls to zero, and is maximum for a circular target of diameter 2 degrees. The spatial characteristics of this temporal filter were measured with a background field consisting of alternate steady and flickering bars. The resulting spatial frequency curve peaks at 1 cycle deg-1 for all background illuminations and is independent of the background grating orientation. This spatial response differs significantly from the IMG spatial functions observed with a background grating (Barbur and Ruddock, 1980). The spatial and temporal responses reviewed above exhibit similar parametric variations and we therefore associate them with a single spatio-temporal filter, ST2. A second temporal response, with low-pass frequency characteristics, was observed with a background field consisting of two matched gratings, presented in spatial and temporal antiphase. This response has parametric properties similar to those of the IMG spatial response described previously by Barbur and Ruddock (1980), thus we associated the two sets of data with a single spatio-temporal filter, ST1. We show that the ST2 responses can be obtained by combining ST1 responses, and we present a network incorporating the two filters. We review other psychophysical studies which imply the activity of two spatio-temporal filters with properties of the kind revealed in our studies. We argue that filter ST1 has properties equivalent to those of X-type and filter ST2 has properties equivalent to those of Y-type electrophysiological mechanisms. PMID:6615916

Holliday, I E; Ruddock, K H

1983-01-01

266

Fiber optic vibration sensor  

DOEpatents

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity. 2 figures.

Dooley, J.B.; Muhs, J.D.; Tobin, K.W.

1995-01-10

267

Fiber optic vibration sensor  

DOEpatents

A fiber optic vibration sensor utilizes two single mode optical fibers supported by a housing with one optical fiber fixedly secured to the housing and providing a reference signal and the other optical fiber having a free span length subject to vibrational displacement thereof with respect to the housing and the first optical fiber for providing a signal indicative of a measurement of any perturbation of the sensor. Damping or tailoring of the sensor to be responsive to selected levels of perturbation is provided by altering the diameter of optical fibers or by immersing at least a portion of the free span length of the vibration sensing optical fiber into a liquid of a selected viscosity.

Dooley, Joseph B. (Harriman, TN); Muhs, Jeffrey D. (Lenoir City, TN); Tobin, Kenneth W. (Harriman, TN)

1995-01-01

268

Linking Work Design and Corporate Social Responsibility Through an Exploratory Model for the Interdependency of Work Characteristics and Corporate Social Responsibility Orientation  

E-print Network

characteristics that can result in desired organizational outcomes. Specifically, in current times, organizations are looking to develop socially responsible outcomes, otherwise referred as corporate social responsibility (CSR). A possible link between work design...

Kurup, Priya Darshini

2012-02-14

269

Frequency-response method for determination of dynamic stability characteristics of airplanes with automatic controls  

NASA Technical Reports Server (NTRS)

A frequency-response method for determining the critical control-gearing and hunting oscillations of airplanes with automatic pilots is presented. The method is graphical and has several advantages over the standard numerical procedure based on Routh's discriminant. The chief advantage of the method is that direct use can be made of the measured response characteristics of the automatic pilot. This feature is especially useful in determining the existence, amplitude, and frequency of the hunting oscillations that may be present when the automatic pilot has nonlinear dynamic characteristics. Several examples are worked out to illustrate the application of the frequency-response method in determining the effect of automatic-pilot lag or lead on critical control gearing and in determining the amplitude and frequency hunting. It is shown that the method may be applied to the case of a control geared to airplane motions about two axes.

Greenberg, Harry

1947-01-01

270

Vibration Labs to Help Achieve a Resonance in Learning  

NSDL National Science Digital Library

A sequence of laboratories has been designed and implemented in an undergraduate course in mechanical vibrations to introduce students to experimental aspects of vibrations and experimental modal analysis. Unfortunately, undergraduate vibration courses, especially if they do not have a lab associated with them, are often perceived by many students to be courses in differential equations. By exposing students to vibration measurement instrumentation such as accelerometers and dynamic signal analyzers, and by allowing them to take experimental data, calculate frequency response functions, and identify system parameters and mode shapes, student learning and motivation is enhanced. One characteristic of the labs described in this paper, in contrast to other vibrations labs discussed in the literature, is the way each lab builds upon the previous one and the fact students test real engineering structures. The initial labs in the course use Electronic Control Products (ECP) hardware and introduce the idea of frequency response functions (FRFs) and system identification. After students are familiar with these ideas, they progress to using PHOTON IIs (a 32 bit, 4 channel data acquisition system), RT Pro for data acquisition and signal processing, and DIAMOND for system identification and mode shape animation. In this paper the labs will be described and assessment results presented as to their efficacy.

Cornwell, Philip

2011-06-22

271

Ride quality criteria. [transportation system interior and passenger response to environment  

NASA Technical Reports Server (NTRS)

Ride quality refers to the interior or passenger environment of a transportation system as well as the passenger response to the environment. Ride quality factors are illustrated with the aid of a diagram presenting inputs to vehicle, the vehicle transfer function, the ride environment, the passenger response function, and the passenger ride response. The reported investigation considers the ride environment as measured on a variety of air and surface vehicles, the passenger response to the environment as determined from laboratory and field surveys, and criteria/standards for vibration, noise, and combined stimuli. Attention is given to the vertical vibration characteristics in cruise for aircraft and automobile, the aircraft vibration levels for various operating regimes, comparative noise levels during cruise, the discomfort level for a 9 Hz sinusoidal vibration, equal discomfort contours for vertical vibration, subjective response to noise in a speech situation, and noise and vibration levels for constant discomfort contours.

Stephens, D. G.

1977-01-01

272

Consideration of nonlinear vibration characteristic of object for irradiating highintensity ultrasonic waves by a point-convergence-type aerial ultrasonic source  

NASA Astrophysics Data System (ADS)

We considered a noncontact method that can detect internal defects in materials by analyzing frequency information obtained from the vibration of an object excited with highintensity ultrasonic waves. From our result, it is found that this method is able to detect internal defects in materials.

Osumi, Ayumu; Ito, Youichi

2012-09-01

273

Characteristics of invertebrates consumed by mallards and prey response to wetland flooding schedules  

Microsoft Academic Search

We examined characteristics of the invertebrates consumed by mallards (Anas platyrhynchos) and green-winged teals (Anas crecca) and responses of these invertebrates to manipulations of flooding date in Suisun Marsh, Solano County, CA. Numbers ofChironomus stigmaterus midge larvae (Chironomidae) andEogammarus confervicolus amphipods (Gammaridae) in mallard esophageal samples were positively correlated with abundance of these invertebrates in\\u000a wetlands. Mallards primarily consumed large

Darold P. Batzer; Monica McGee; Vincent H. Resh; R. Robert Smith

1993-01-01

274

Behavioral Responses of Daphnia Magna to Stresses of Chemicals with Different Toxic Characteristics  

Microsoft Academic Search

Behavior of an organism is affected by exposure to toxic chemicals. However, less has been known about behavioral responses\\u000a of an organism to stresses of toxic chemicals with different toxic characteristics. In present work, Daphnia magna Straus was exposed to gradient concentrations of deltamethrin, chlorothalonil and nitrofen and the behavioral changes of\\u000a Daphnia magna under different stress were examined. The

Zongming Ren; Zhiliang Li; Mei Ma; Zijian Wang; Rongshu Fu

2009-01-01

275

Characteristics of identifying linear dynamic models from impulse response data using Prony analysis  

SciTech Connect

The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general ``rules-of-thumb`` for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

Trudnowski, D.J.

1992-12-01

276

Characteristics of identifying linear dynamic models from impulse response data using Prony analysis  

SciTech Connect

The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general rules-of-thumb'' for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques; different parent system configurations; and a large variety of underlying noise characteristics.

Trudnowski, D.J.

1992-12-01

277

Characteristics of identifying linear dynamic models from impulse response data using Prony analysis  

NASA Astrophysics Data System (ADS)

The purpose of the study was to investigate the characteristics of fitting linear dynamic models to the impulse response of oscillatory dynamic systems using Prony analysis. Many dynamic systems exhibit oscillatory responses with multiple modes of oscillations. Although the underlying dynamics of such systems are often nonlinear, it is frequently possible and very useful to represent the system operating about some set point with a linear model. Derivation of such linear models can be done using two basic approaches: model the system using theoretical derivations and some linearization method such as a Taylor series expansion; or use a curve-fitting technique to optimally fit a linear model to specified system response data. Prony analysis belongs to the second class of system modeling because it is a method of fitting a linear model to the impulse response of a dynamic system. Its parallel formulation inherently makes it well suited for fitting models to oscillatory system data. Such oscillatory dynamic effects occur in large synchronous-generator-based power systems in the form of electromechanical oscillations. To study and characterize these oscillatory dynamics, BPA has developed computer codes to analyze system data using Prony analysis. The objective of this study was to develop a highly detailed understanding of the properties of using Prony analysis to fit models to systems with characteristics often encountered in power systems. This understanding was then extended to develop general 'rules-of-thumb' for using Prony analysis. The general characteristics were investigated by performing fits to data from known linear models under controlled conditions. The conditions studied include various mathematical solution techniques, different parent system configurations, and a large variety of underlying noise characteristics.

Trudnowski, D. J.

1992-12-01

278

Vibration analysis and experiment of the helicopter rotor test stand transmission  

Microsoft Academic Search

The transmission vibration characteristics of the helicopter test stand was analyzed using the transfer matrix method, including the torsional vibration and the lateral vibration. The torsional vibration modal frequencies and the modal shapes of each order were obtained by analyzing the torsional vibration of the rotor test stand transmission; What's more, each order natural frequency and the relationship between the

Su Xunwen; Wang Shaoping; Zhu Dongmei

2011-01-01

279

Analysis of the Dynamic Response of a Rolling String-Type Tire Model to Lateral Wheel-Plane Vibrations  

Microsoft Academic Search

A theory has been developed for the analysis and prediction of the dynamic frequency response of lateral force and moment acting upon a pneumatic tire when the wheel is moved laterally and swivelled about the vertical axis. The theory establishes the force and moment response of a tire model which consists of a stretched circular string with mass, elastically supported

HANS B. PACEJKA

1972-01-01

280

Application of the Method of Stein and Sanders to the Calculation of Vibration Characteristics of a 45 deg Delta-Wing Specimen  

NASA Technical Reports Server (NTRS)

Generalized influence coefficients are calculated by the method of NACA TN 3640 for a large-scale, built-up, 450 delta-wing specimen. These are used together with appropriate generalized masses to obtain the natural modes and frequencies in symmetric and antisymmetric free-free vibration. The resulting frequencies are compared with those obtained experimentally and are found to be consistently high. Possible sources of the disparities are discussed.

Hedgepeth, John M.; Warner, Paul G., Jr.

1959-01-01

281

Experimental validation of a numerical model for subway induced vibrations  

NASA Astrophysics Data System (ADS)

This paper presents the experimental validation of a coupled periodic finite element-boundary element model for the prediction of subway induced vibrations. The model fully accounts for the dynamic interaction between the train, the track, the tunnel and the soil. The periodicity or invariance of the tunnel and the soil in the longitudinal direction is exploited using the Floquet transformation, which allows for an efficient formulation in the frequency-wavenumber domain. A general analytical formulation is used to compute the response of three-dimensional invariant or periodic media that are excited by moving loads. The numerical model is validated by means of several experiments that have been performed at a site in Regent's Park on the Bakerloo line of London Underground. Vibration measurements have been performed on the axle boxes of the train, on the rail, the tunnel invert and the tunnel wall, and in the free field, both at the surface and at a depth of 15 m. Prior to these vibration measurements, the dynamic soil characteristics and the track characteristics have been determined. The Bakerloo line tunnel of London Underground has been modelled using the coupled periodic finite element-boundary element approach and free field vibrations due to the passage of a train at different speeds have been predicted and compared to the measurements. The correspondence between the predicted and measured response in the tunnel is reasonably good, although some differences are observed in the free field. The discrepancies are explained on the basis of various uncertainties involved in the problem. The variation in the response with train speed is similar for the measurements as well as the predictions. This study demonstrates the applicability of the coupled periodic finite element-boundary element model to make realistic predictions of the vibrations from underground railways.

Gupta, S.; Degrande, G.; Lombaert, G.

2009-04-01

282

A method of investigating the phase response characteristic of the ionospheric scattering communications channel  

NASA Technical Reports Server (NTRS)

A method is proposed for measuring the phase difference fluctuations between vibrations at different frequencies that result from scattering properties of the medium. The measurement equipment is described, along with an ideal communication channel.

Yakovets, A. F.

1972-01-01

283

Vibration analysis of bimodulus laminated cylindrical panels  

NASA Astrophysics Data System (ADS)

This paper deals with the flexural vibration behavior of bimodular laminated composite cylindrical panels with various boundary conditions. The formulation is based on first order shear deformation theory and Bert's constitutive model. The governing equations are derived using finite element method and Lagrange's equation of motion. An iterative eigenvalue approach is employed to obtain the positive and negative half cycle free vibration frequencies and corresponding mode shapes. A detailed parametric study is carried out to study the influences of thickness ratio, aspect ratio, lamination scheme, edge conditions and bimodularity ratio on the free vibration characteristics of bimodulus angle- and cross-ply composite laminated cylindrical panels. It is interesting to observe that there is a significant difference between the frequencies of positive and negative half cycles depending on the panel parameters. Through the thickness distribution of modal stresses for positive half cycle is significantly different from that for negative half cycle unlike unimodular case wherein the stresses at a particular location in negative half cycle would be of same magnitude but of opposite sign of those corresponding to positive half cycle. Finally, the effect of bimodularity on the steady state response versus forcing frequency relation is studied for a typical case.

Khan, K.; Patel, B. P.; Nath, Y.

2009-03-01

284

Using cross correlations of turbulent flow-induced ambient vibrations to estimate the structural impulse response. Application to structural health monitoring.  

PubMed

It has been demonstrated theoretically and experimentally that an estimate of the impulse response (or Green's function) between two receivers can be obtained from the cross correlation of diffuse wave fields at these two receivers in various environments and frequency ranges: ultrasonics, civil engineering, underwater acoustics, and seismology. This result provides a means for structural monitoring using ambient structure-borne noise only, without the use of active sources. This paper presents experimental results obtained from flow-induced random vibration data recorded by pairs of accelerometers mounted within a flat plate or hydrofoil in the test section of the U.S. Navy's William B. Morgan Large Cavitation Channel. The experiments were conducted at high Reynolds number (Re > 50 million) with the primary excitation source being turbulent boundary layer pressure fluctuations on the upper and lower surfaces of the plate or foil. Identical deterministic time signatures emerge from the noise cross-correlation function computed via robust and simple processing of noise measured on different days by a pair of passive sensors. These time signatures are used to determine and/or monitor the structural response of the test models from a few hundred to a few thousand Hertz. PMID:17471715

Sabra, Karim G; Winkel, Eric S; Bourgoyne, Dwayne A; Elbing, Brian R; Ceccio, Steve L; Perlin, Marc; Dowling, David R

2007-04-01

285

Effects of train noise and vibration on human heart rate during sleep: an experimental study  

PubMed Central

Objectives Transportation of goods on railways is increasing and the majority of the increased numbers of freight trains run during the night. Transportation noise has adverse effects on sleep structure, affects the heart rate (HR) during sleep and may be linked to cardiovascular disease. Freight trains also generate vibration and little is known regarding the impact of vibration on human sleep. A laboratory study was conducted to examine how a realistic nocturnal railway traffic scenario influences HR during sleep. Design Case–control. Setting Healthy participants. Participants 24 healthy volunteers (11 men, 13 women, 19–28?years) spent six consecutive nights in the sleep laboratory. Interventions All participants slept during one habituation night, one control and four experimental nights in which train noise and vibration were reproduced. In the experimental nights, 20 or 36 trains with low-vibration or high-vibration characteristics were presented. Primary and secondary outcome measures Polysomnographical data and ECG were recorded. Results The train exposure led to a significant change of HR within 1?min of exposure onset (p=0.002), characterised by an initial and a delayed increase of HR. The high-vibration condition provoked an average increase of at least 3?bpm per train in 79% of the participants. Cardiac responses were in general higher in the high-vibration condition than in the low-vibration condition (p=0.006). No significant effect of noise sensitivity and gender was revealed, although there was a tendency for men to exhibit stronger HR acceleration than women. Conclusions Freight trains provoke HR accelerations during sleep, and the vibration characteristics of the trains are of special importance. In the long term, this may affect cardiovascular functioning of persons living close to railways. PMID:23793667

Croy, Ilona; Smith, Michael G; Waye, Kerstin Persson

2013-01-01

286

Point Response Characteristics for the CERES/EOS-PM, FM3 & FM4 instruments.  

NASA Technical Reports Server (NTRS)

This paper describes the point source functions (PSF s) of the Clouds and the Earth s Radiant Energy System (CERES,) Earth Observing System (EOS,) afternoon platform (PM,) Flight Model 3 (FM3,) and Flight Model 4 (FM4) scanning instruments. The PSF (also known as the Point Response Function, or PRF) is vital to the accurate geo-location of the remotely sensed radiance measurements acquired by the instrument. This paper compares the characteristics of the FM3 and FM4 instruments with the earlier Proto Flight Model (PFM) on the Tropical Rainfall Measuring Mission (TRMM) platform, and the FM1 and FM2 Models on the EOS morning orbiting (AM) platform, which has recently been renamed "Terra". All of the PSF s were found to be quite comparable, and the previously noted "spreading" characteristic of the window (water vapor) channel PSF is analyzed Keywords: PSF, PRF, CERES, TRMM, EOS, Earth Radiation Budget

Paden, Jack; Smith, G. Louis; Lee, Robert B., III; Pandey, Dhirendra K.; Priestley, Kory J.; Thomas, Susan; Wilson, Robert S.

1999-01-01

287

Parametric Optimization of Ares I Propellant Slosh Characteristics Using Frequency Response Criteria  

NASA Technical Reports Server (NTRS)

A novel technique for developing propellant slosh damping requirements with respect to the stability characteristics of large flexible launch vehicles is presented. A numerical algorithm is devised which allows an automated software program to rapidly converge to pseudo-optimal solutions that minimize required propellant slosh damping for multiple tanks while maintaining constraints on the frequency response characteristics of a particular open-loop plant transfer function. An implementation of the algorithm using a high-order linear model of the Ares I plant dynamics considers all relevant dynamic interactions of flexible body modes, propellant slosh, and nozzle inertia effects. A high-resolution propellant damping requirements table is produced that can be used for baffle design. The method is demonstrated to provide exceptional speed and accuracy when compared with the alternative human-in-the-loop approach.

Orr, Jeb S.; Hall, Charles E.

2009-01-01

288

A combined finite element–stiffness equation transfer method for steady state vibration response analysis of structures  

Microsoft Academic Search

An extended finite element transfer matrix method, in combination with stiffness equation transfer, is applied to dynamic response analysis of the structures under periodic excitations. In the present method, the transfer of state vectors from left to right in a combined finite element-transfer matrix (FE-TM) method is changed into the transfer of general stiffness equations of every section from left

Huiyu Xue

2003-01-01

289

Experimental Studies on Dynamic Vibration Absorber using Shape Memory Alloy (NiTi) Springs  

SciTech Connect

Shape memory alloy (SMA) springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some vibration control concepts utilizing unique characteristics of SMA's will be presented in this paper.A dynamic vibration absorber (DVA) using shape memory alloy (SMA) actuator is developed for attenuation of vibration in a cantilever beam. The design procedure of the DVA is presented. The system consists of a cantilever beam which is considered to generate the real-time vibration using shaker. A SMA spring is used with a mass attached to its end. The stiffness of the SMA spring is dynamically varied in such a way to attenuate the vibration. Both simulation and experimentation are carried out using PID controller. The experiments were carried out by interfacing the experimental setup with a computer using LabVIEW software, Data acquisition and control are implemented using a PCI data acquisition card. Standard PID controllers have been used to control the vibration of the beam. Experimental results are used to demonstrate the effectiveness of the controllers designed and the usefulness of the proposed test platform by exciting the structure at resonance. In experimental setup, an accelerometer is used to measure the vibration which is fed to computer and correspondingly the SMA spring is actuated to change its stiffness to control the vibration. The results obtained illustrate that the developed DVA using SMA actuator is very effective in reducing structural response and have great potential to be an active vibration control medium.

Kumar, V. Raj; Kumar, M. B. Bharathi Raj; Kumar, M. Senthil [Department of Mechanical Engineering, PSG College of Technology, Coimbatore (India)

2011-10-20

290

Effects of housing and individual coping characteristics on immune responses of pigs.  

PubMed

The impact of environmental factors on immune responses may be influenced by coping characteristics of the individuals under study. The behavioral response of pigs in a so-called Backtest early in life seems indicative of their coping style at a later age. The present study investigated the effects of housing, barren versus enriched, and coping style, as assessed by Backtest classification, on immune responses of pigs. Pigs were housed either without a rooting substrate (barren housing) or in identical pens enriched with deep straw bedding (enriched housing) from birth. During the suckling period, pigs were subjected to the Backtest. Each pig was restrained on its back for 1 min and the resistance (i.e., number of escape attempts) was scored. Pigs classified as 'high-' or 'low-resisting' (HR and LR, respectively) were immunized with di-nitrophenyl-conjugated keyhole limpet haemocyanin (DNP-KLH) at 9 weeks of age. Blood samples were drawn before immunization (Day 0) and weekly thereafter, until Day 35. KLH-specific lymphocyte proliferation following immunization was higher for HR pigs than for LR pigs. Housing did not affect proliferative responses. Housing and coping style interacted in their effect on KLH-specific humoral immune responses. LR pigs from barren housing showed higher KLH-specific antibody titers than LR pigs from enriched housing. Differently housed HR pigs, however, showed similar antibody titers. These findings support other research indicating that individual coping styles of pigs are reflected in their immune responses. More important, the present study demonstrates that effects of housing on humoral immune responses of pigs may differ for pigs with divergent coping styles. PMID:12834801

Bolhuis, J Elizabeth; Parmentier, Henk K; Schouten, Willem G P; Schrama, Johan W; Wiegant, Victor M

2003-07-01

291

Problems and Challenges Vibrations  

E-print Network

, but is not necessary for many standard measurements. Mounting all optical components on vibration insulation posts further reduced vibrations. Concerning the suppression of vibration-induced measurement problems58 Problems and Challenges Vibrations: One of the key problems for the bulge tester is vibration

Huston, Dryver R.

292

Whole-body vibration perception thresholds  

NASA Astrophysics Data System (ADS)

This paper presents the results of a series of laboratory experiments concerned with perception thresholds for whole-body vibration. The nature of absolute perception thresholds is discussed and a method of determining vibration thresholds, based upon signal detection theory, is proposed. Thresholds of subjects exposed to x-, y- and z-axis sinusoidal vibration were determined for sitting and standing subjects (from 2 to 100 Hz). Perception thresholds have also been determined for supine subjects exposed to vertical ( x-axis) sinusoidal vibration (10-63 Hz). In additional experiments the effects of complex (e.g., random) vibration and the effects of duration on the perception thresholds were investigated. The relation between perception thresholds and vibration levels, said by subjects to be unacceptable if they occurred in their own homes, was investigated as well as the effects of subjects' personality and the visual and acoustic conditions in the laboratory. For the vertical vibration of seated subjects no significant differences were found between the responses of male and female subjects. Significant differences were found between perception thresholds for sitting and standing postures. The median threshold was approximately 0·01 m/s 2 r.m.s. between 2 and 100 Hz. Perception thresholds for x-axis and y-axis vibration were not significantly different in either sitting or standing subjects but significant differences in thresholds were found between sitting and standing positions for both x-axis and y-axis vibration. Subjects tended to be more sensitive to vibration when lying than when sitting or standing. The results suggested that the perception of random vibrations can be predicted from a knowledge of the perception of its component vibrations. The number of cycles of vibration did not affect perception thresholds for vibration durations of more than about 0·25 s. Some assessments suggested that vibration at more than twice the perception threshold may not be acceptable if it occurs in the home.

Parsons, K. C.; Griffin, M. J.

1988-03-01

293

Dose response characteristics of polymethacrylic acid gel (PMAAG) for a polymerization-based dosimeter using NMR.  

PubMed

The radiation-response characteristics of polymetharylic acid gel dosimeter prepared with different concentrations of monomer and cross-linker is described in these studies. The dosimeters were prepared under the hypoxic condition in a glove box and were then irradiated with gamma-rays produced by Co-60 radionuclide that was generated at 1.25MeV energy. The irradiation took place at different doses ranged from 0Gy to 19Gy. Due to the radiation activities, chain-reaction polymerisation processes had taken place in the formation of polymethacrylic acid (PMAA) gel, which cause the dose response mechanism increased in the NMR relaxation rates of protons. It has been observed that for higher concentration of monomer and cross-linker, the polymerization rate was increased. PMID:15468893

Iskandar, S M; Elias, S; Jumiah, H; Asri, M T M; Masrianis, A; Ab Rahman, M Z; Taiman, K; Abdul Rashid, M Y

2004-05-01

294

Coupling between plate vibration and acoustic radiation  

NASA Technical Reports Server (NTRS)

A detailed numerical investigation of the coupling between the vibration of a flexible plate and the acoustic radiation is performed. The nonlinear Euler equations are used to describe the acoustic fluid while the nonlinear plate equation is used to describe the plate vibration. Linear, nonlinear, and quasi-periodic or chaotic vibrations and the resultant acoustic radiation are analyzed. We find that for the linear plate response, acoustic coupling is negligible. However, for the nonlinear and chaotic responses, acoustic coupling has a significant effect on the vibration level as the loading increases. The radiated pressure from a plate undergoing nonlinear or chaotic vibrations is found to propagate nonlinearly into the far-field. However, the nonlinearity due to wave propagation is much weaker than that due to the plate vibrations. As the acoustic wave propagates into the far-field, the relative difference in level between the fundamental and its harmonics and subharmonics decreases with distance.

Frendi, Abdelkader; Maestrello, Lucio; Bayliss, Alvin

1992-01-01

295

Vibrations of Euler's disk.  

PubMed

A model of a partially deformable Euler disk is presented that allows transverse vibrations to be treated with the techniques of classical analytical mechanics. The model clearly shows that the increasing audible frequency produced during motion can be directly related to the forcing effect of the reaction and the angular velocity of the contact point. The material of the disk seems to play a role in affecting the intensity and quality of the sound, but not its pitch. Moreover, the friction force grows rapidly with the decline of the disk, thus causing the slipping that is partially responsible for the abrupt end of the motion. The model also supports the conjecture [P. Kessler and O. M. O'Reilly, Regul. Chaotic Dyn. 7, 49 (2002)] that the vibrations themselves contribute to this phenomenon by causing a loss of contact with the surface at small angles of inclination. PMID:16089897

Villanueva, Roberto; Epstein, Marcelo

2005-06-01

296

ROCView: prototype software for data collection in jackknife alternative free-response receiver operating characteristic analysis  

PubMed Central

ROCView has been developed as an image display and response capture (IDRC) solution to image display and consistent recording of reader responses in relation to the free-response receiver operating characteristic paradigm. A web-based solution to IDRC for observer response studies allows observations to be completed from any location, assuming that display performance and viewing conditions are consistent with the study being completed. The simplistic functionality of the software allows observations to be completed without supervision. ROCView can display images from multiple modalities, in a randomised order if required. Following registration, observers are prompted to begin their image evaluation. All data are recorded via mouse clicks, one to localise (mark) and one to score confidence (rate) using either an ordinal or continuous rating scale. Up to nine “mark-rating” pairs can be made per image. Unmarked images are given a default score of zero. Upon completion of the study, both true-positive and false-positive reports can be downloaded and adapted for analysis. ROCView has the potential to be a useful tool in the assessment of modality performance difference for a range of imaging methods. PMID:22573294

Thompson, J; Hogg, P; Thompson, S; Manning, D; Szczepura, K

2012-01-01

297

Characteristics of resistivity log response of oil layers under polymer flooding  

NASA Astrophysics Data System (ADS)

Resistivity log responses are different when the oil layers is filled by a polymer solution or water and it seriously affects the log interpretation of the water flooded layer. In this paper, we first analyze the electrical properties of the polymer solution. Then, according to the different processes for polymer flooding the reservoir, we perform rock resistivity experiments and analyze the rock resistivity variations in different displacement phases. We also compare the resistivity log responses of oil layers filled with the polymer solution to those filled with water. The results show that when displacing the oil-bearing core by different polymers, the resistivity changes monotonously decrease and show either "W" type or "S" type. The resistivity log responses are weak when displacing water and there is no flooded show if the oil layer is injected by a fresh water polymer solution. If the oil layer is injected by a sewage polymer solution, the resistivity log response has similar characteristic as a polluted water flooded layer.

Yu, Jun; Pan, Bao-Zhi; Yang, Qing-Shan

2012-06-01

298

Nonlinear response and failure characteristics of internally pressurized composite cylindrical panels  

NASA Technical Reports Server (NTRS)

Results of an experimental and analytical study of the nonlinear response and failure characteristics of internally pressurized 4- to 16-ply-thick graphite-epoxy cylindrical panels are presented. Specimens with clamped boundaries simulating the skin between two frames and two stringers of a typical transport fuselage were tested to failure. Failure results of aluminum specimens are compared with the graphite-epoxy test results. The specimens failed at their edges where the local bending gradients and interlaminar stresses are maximum. STAGS nonlinear two-dimensional shell analysis computer code results are used to identify regions of the panels where the response is independent of the axial coordinate. A geometrically nonlinear one-dimensional cylindrical panel analysis was derived and used to determine panel response and interlaminar stresses. Inclusion of the geometric nonlinearity was essential for accurate prediction of panel response. The maximum stress failure criterion applied to the predicted tensile stress in the fiber direction agreed best with the experimentally determined first damage pressures.

Boitnott, R. L.; Johnson, E. R.; Starnes, J. H.

1985-01-01

299

Comprehensive studies of response characteristics of organic photodetectors based on rubrene and C60  

NASA Astrophysics Data System (ADS)

We studied the transient response characteristics of organic photodetectors composing of high mobility materials of rubrene and C60, respectively, as donor and acceptor. It was found that the response speed was limited by the delay time of both exciton diffusion and transit, and an anomalous phenomenon that the bandwidth decreases as the reverse bias increases was found for the first time. The investigation of frequency dependence at different device structures and light excitations demonstrated that the light absorption of rubrene prevents the photodetector from obtaining a fast response. With the help of magnetic field effect study, it was clearly elucidated that the slow diffusion time of the long lifetime triplet excitons generated from singlet fission in rubrene limited the bandwidth of the device. Moreover, the simulation of the response of photodetector under transient and steady state by exciton transport-diffusion equation showed that the exciton dissociation efficiency in rubrene increases more quickly than that in C60, which should account for the negative dependence of bandwidth on the reverse bias in rubrene-based device.

Yang, Dezhi; Xu, Kai; Zhou, Xiaokang; Wang, Yanping; Ma, Dongge

2014-06-01

300

Comparison of aortic and carotid baroreflex stimulus-response characteristics in humans  

NASA Technical Reports Server (NTRS)

In order to characterize the stimulus-response relationships of the arterial, aortic, and carotid baroreflexes in mediating cardiac chronotropic function, we measured heart rate (HR) responses elicited by acute changes in mean arterial pressure (MAP) and carotid sinus pressure (CSP) in 11 healthy individuals. Arterial (aortic + carotid) baroreflex control of HR was quantified using ramped changes in MAP induced by bolus injection of phenylephrine (PE) and sodium nitroprusside (SN). To assess aortic-cardiac responses, neck pressure (NP) and suction (NS) were applied during PE and SN administration, respectively, to counter alterations in CSP thereby isolating the aortic baroreflex. Graded levels of NP and NS were delivered to the carotid sinus using a customized neck collar device to assess the carotid-cardiac baroreflex, independent of drug infusion. The operating characteristics of each reflex were determined from the logistic function of the elicited HR response to the induced change in MAP. The arterial pressures at which the threshold was located on the stimulus-response curves determined for the arterial, aortic and carotid baroreflexes were not significantly different (72+/-4, 67+/-3, and 72+/-4 mm Hg, respectively, P > 0.05). Similarly, the MAP at which the saturation of the reflex responses were elicited did not differ among the baroreflex arcs examined (98+/-3, 99+/-2, and 102+/-3 mm Hg, respectively). These data suggest that the baroreceptor populations studied operate over the same range of arterial pressures. This finding indicates each baroreflex functions as both an important anti-hypotensive and anti-hypertensive mechanism. In addition, this investigation describes a model of aortic baroreflex function in normal healthy humans, which may prove useful in identifying the origin of baroreflex dysfunction in disease- and training-induced conditions.

Smith, S. A.; Querry, R. G.; Fadel, P. J.; Weiss, M. W.; Olivencia-Yurvati, A.; Shi, X.; Raven, P. B.

2001-01-01

301

Evaluation of space shuttle main engine fluid dynamic frequency response characteristics  

NASA Technical Reports Server (NTRS)

In order to determine the POGO stability characteristics of the space shuttle main engine liquid oxygen (LOX) system, the fluid dynamic frequency response functions between elements in the SSME LOX system was evaluated, both analytically and experimentally. For the experimental data evaluation, a software package was written for the Hewlett-Packard 5451C Fourier analyzer. The POGO analysis software is documented and consists of five separate segments. Each segment is stored on the 5451C disc as an individual program and performs its own unique function. Two separate data reduction methods, a signal calibration, coherence or pulser signal based frequency response function blanking, and automatic plotting features are included in the program. The 5451C allows variable parameter transfer from program to program. This feature is used to advantage and requires only minimal user interface during the data reduction process. Experimental results are included and compared with the analytical predictions in order to adjust the general model and arrive at a realistic simulation of the POGO characteristics.

Gardner, T. G.

1980-01-01

302

Turbine blade vibration dampening  

DOEpatents

The present turbine wheel assembly increases component life and turbine engine longevity. The combination of the strap and the opening combined with the preestablished area of the outer surface of the opening and the preestablished area of the outer circumferential surface of the strap and the friction between the strap and the opening increases the life and longevity of the turbine wheel assembly. Furthermore, the mass "M" or combined mass "CM" of the strap or straps and the centrifugal force assist in controlling vibrations and damping characteristics.

Cornelius, Charles C. (San Diego, CA); Pytanowski, Gregory P. (San Diego, CA); Vendituoli, Jonathan S. (San Diego, CA)

1997-07-08

303

Leaf gas exchange characteristics of three neotropical mangrove species in response to varying hydroperiod.  

PubMed

We determined how different hydroperiods affected leaf gas exchange characteristics of greenhouse-grown seedlings (2002) and saplings (2003) of the mangrove species Avicennia germinans (L.) Stearn., Laguncularia racemosa (L.) Gaertn. f., and Rhizophora mangle L. Hydroperiod treatments included no flooding (unflooded), intermittent flooding (intermittent), and permanent flooding (flooded). Plants in the intermittent treatment were measured under both flooded and drained states and compared separately. In the greenhouse study, plants of all species maintained different leaf areas in the contrasting hydroperiods during both years. Assimilation-light response curves indicated that the different hydroperiods had little effect on leaf gas exchange characteristics in either seedlings or saplings. However, short-term intermittent flooding for between 6 and 22 days caused a 20% reduction in maximum leaf-level carbon assimilation rate, a 51% lower light requirement to attain 50% of maximum assimilation, and a 38% higher demand from dark respiration. Although interspecific differences were evident for nearly all measured parameters in both years, there was little consistency in ranking of the interspecific responses. Species by hydroperiod interactions were significant only for sapling leaf area. In a field study, R. mangle saplings along the Shark River in the Everglades National Park either demonstrated no significant effect or slight enhancement of carbon assimilation and water-use efficiency while flooded. We obtained little evidence that contrasting hydroperiods affect leaf gas exchange characteristics of mangrove seedlings or saplings over long time intervals; however, intermittent flooding may cause short-term depressions in leaf gas exchange. The resilience of mangrove systems to flooding, as demonstrated in the permanently flooded treatments, will likely promote photosynthetic and morphological adjustment to slight hydroperiod shifts in many settings. PMID:16585041

Krauss, Ken W; Twilley, Robert R; Doyle, Thomas W; Gardiner, Emile S

2006-07-01

304

Vibrational testing of optical fiber connector joints  

NASA Technical Reports Server (NTRS)

An experimental study was performed to determine the effects of vibration on the propagation of light through SMA- and ST-type fiber-optic connectors. A multimode, fiber-optic link was vibrated from 0 to 10,000 Hz at a constant peak acceleration along the connector transverse and longitudinal axes. All other environmental parameters were ambient. Transfer characteristics through the connection were examined as a function of vibrational frequency using both laser and light-emitting diode (LED) light to illuminate the system. Slight differences in operation between the SMA and ST connectors were observed with no appreciative attenuation as a result of vibration. Vibration did cause the constant-amplitude input light to be modulated in the connector; however, the amplitude of vibration-induced noise was less than 3 standard deviations from the mean.

Sovie, Amy L.; Madzsar, George C.

1990-01-01

305

Vibrational testing of optical fiber connector joints  

NASA Technical Reports Server (NTRS)

An experimental study was performed to determine the effects of vibration on the propagation of light through SMA- and ST-type fiber-optic connectors. A multimode, fiber-optic link was vibrated from 0 to 10,000 Hz at a constant peak acceleration along the connector transverse and longitudinal axes. All other environmental parameters were ambient. Transfer characteristics through the connection were examined as a function of vibrational frequency using both laser and light-emitting diode (LED) light to illuminate the system. Slight differences in operation between the SMA and ST connectors were observed with no appreciative attenuation as a result of vibration. Vibration did cause constant-amplitude input light to be modulated in the connector; however; the amplitude of vibration-induced noise was less than 3 standard deviations from the mean.

Sovie, Amy L.; Madzsar, George C.

1990-01-01

306

Vibration dampers for cryogenic turbomachinery  

NASA Technical Reports Server (NTRS)

This paper describes the development of effective and reliable minimum-weight and minimum-envelope vibration dampers for cryogenic turbines. To meet this objective, a high speed test rig was designed and fabricated, which is currently used to test a curved beam type damper. The operation, capacity, structural characteristics, measurement system, and safety features of the cryogenic damper test rig are discussed.

Palazzolo, Alan B.; Olan, Emmanuel; Ibrahim, Azman Syed; Kascak, Albert F.

1990-01-01

307

Free Vibration of the High Temperature Superconducting Maglev Vehicle Model  

Microsoft Academic Search

Free vibration of the high temperature superconducting (HTS) Maglev vehicle model has been investigated after an impulse force over the permanent magnet guideway. The impulse force was used to simulate the external disturbances on the HTS Maglev vehicle so as to study its vibration characteristics. In the experiments, the free vibration curves of time dependence of acceleration and frequency dependence

Zigang Deng; Jun Zheng; Honghai Song; Lu Liu; Lulin Wang; Ya Zhang; Suyu Wang; Jiasu Wang

2007-01-01

308

Downhole vibration sensing by vibration energy harvesting  

E-print Network

This thesis outlines the design of a prototype electromagnetic induction vibration energy harvesting device for use in a downhole environment. First order models of the necessary components for a generic vibration energy ...

Trimble, A. Zachary

2007-01-01

309

Vibrations transmitted to human subjects through passenger seats and considerations of passenger comfort  

NASA Technical Reports Server (NTRS)

An experimental study was conducted to determine the vertical and lateral vibration-transmission characteristics of several types of transport vehicle seats (two aircraft and one bus) to obtain preliminary estimates and comparisons of the ride acceptability of the various seat types. Results of this investigation indicate that from the standpoint of human comfort the seats exhibit undesirable dynamic response characteristics. Amplification of floor vibrations occurred at the frequencies known to be most critical for human comfort in both vertical and lateral axes. An average transmissibility function for aircraft seats was tabulated together with the associated variability for use by designers who incorporate similar types of seats in their vehicles. The acceptability of vibrations resulting from floor inputs of 0.10g and 0.15g was low over a broad range of frequencies for both axes and all seat types, and was especially low at frequencies where the input was being amplified.

Leatherwood, J. D.

1975-01-01

310

Study on DFIG wind turbines control strategy for improving frequency response characteristics  

NASA Astrophysics Data System (ADS)

The active and reactive power decoupling control for the double-fed induction generator wind turbines(DFIG) does not play a positive role to the frequency response ability of power grid because it performs as the hidden inertia for the power grid. If we want to improve the transient frequency stability of the wind turbine when it is integrated with the system, we must ameliorate its frequency response characteristics. The inability of frequency control due to DFIG decoupling control could be overcome through releasing (or absorbing) a part of the kinetic energy stored in the rotor, so as to increase (or decrease) active power injected to the power system when the deviation of power system frequency appears. This paper discusses the mathematical model of the variable speed DFIG, including the aerodynamic model, pitch control system model, shaft model, generator model and inverter control model, and other key components, focusing on the mathematical model of the converters in rotor side and grid side. Based on the existing model of wind generator, the paper attaches the frequency control model on the platform of the simulation software DIgSILENT/PowerFactory. The simulation results show that the proposed control strategy can response quickly to transient frequency deviation and prove that wind farms can participate in the system frequency regulation to a certain extent. Finally, the result verifies the accuracy and plausibility of the inverter control model which attaches the frequency control module.

Zhao, Dongmei; Wu, Di; Liu, Yanhua; Zhou, Zhiyu

2011-12-01

311

Study on DFIG wind turbines control strategy for improving frequency response characteristics  

NASA Astrophysics Data System (ADS)

The active and reactive power decoupling control for the double-fed induction generator wind turbines(DFIG) does not play a positive role to the frequency response ability of power grid because it performs as the hidden inertia for the power grid. If we want to improve the transient frequency stability of the wind turbine when it is integrated with the system, we must ameliorate its frequency response characteristics. The inability of frequency control due to DFIG decoupling control could be overcome through releasing (or absorbing) a part of the kinetic energy stored in the rotor, so as to increase (or decrease) active power injected to the power system when the deviation of power system frequency appears. This paper discusses the mathematical model of the variable speed DFIG, including the aerodynamic model, pitch control system model, shaft model, generator model and inverter control model, and other key components, focusing on the mathematical model of the converters in rotor side and grid side. Based on the existing model of wind generator, the paper attaches the frequency control model on the platform of the simulation software DIgSILENT/PowerFactory. The simulation results show that the proposed control strategy can response quickly to transient frequency deviation and prove that wind farms can participate in the system frequency regulation to a certain extent. Finally, the result verifies the accuracy and plausibility of the inverter control model which attaches the frequency control module.

Zhao, Dongmei; Wu, Di; Liu, Yanhua; Zhou, Zhiyu

2012-01-01

312

Effects of scaffold architecture on mechanical characteristics and osteoblast response to static and perfusion bioreactor cultures.  

PubMed

Tissue engineering focuses on the repair and regeneration of tissues through the use of biodegradable scaffold systems that structurally support regions of injury while recruiting and/or stimulating cell populations to rebuild the target tissue. Within bone tissue engineering, the effects of scaffold architecture on cellular response have not been conclusively characterized in a controlled-density environment. We present a theoretical and practical assessment of the effects of polycaprolactone (PCL) scaffold architectural modifications on mechanical and flow characteristics as well as MC3T3-E1 preosteoblast cellular response in an in vitro static plate and custom-designed perfusion bioreactor model. Four scaffold architectures were contrasted, which varied in inter-layer lay-down angle and offset between layers, while maintaining a structural porosity of 60 ± 5%. We established that as layer angle was decreased (90° vs. 60°) and offset was introduced (0 vs. 0.5 between layers), structural stiffness, yield stress, strength, pore size, and permeability decreased, while computational fluid dynamics-modeled wall shear stress was increased. Most significant effects were noted with layer offset. Seeding efficiencies in static culture were also dramatically increased due to offset (? 45% to ? 86%), with static culture exhibiting a much higher seeding efficiency than perfusion culture. Scaffold architecture had minimal effect on cell response in static culture. However, architecture influenced osteogenic differentiation in perfusion culture, likely by modifying the microfluidic environment. PMID:24473931

Bartnikowski, Michal; Klein, Travis J; Melchels, Ferry P W; Woodruff, Maria A

2014-07-01

313

Characteristic vibration patterns of odor compounds from bread-baking volatiles upon protein binding: density functional and ONIOM study and principal component analysis.  

PubMed

As the mechanism underlying the sense of smell is unclear, different models have been used to rationalize structure-odor relationships. To gain insight into odorant molecules from bread baking, binding energies and vibration spectra in the gas phase and in the protein environment [7-transmembrane helices (7TMHs) of rhodopsin] were calculated using density functional theory [B3LYP/6-311++G(d,p)] and ONIOM [B3LYP/6-311++G(d,p):PM3] methods. It was found that acetaldehyde ("acid" category) binds strongly in the large cavity inside the receptor, whereas 2-ethyl-3-methylpyrazine ("roasted") binds weakly. Lys296, Tyr268, Thr118 and Ala117 were identified as key residues in the binding site. More emphasis was placed on how vibrational frequencies are shifted and intensities modified in the receptor protein environment. Principal component analysis (PCA) suggested that the frequency shifts of C-C stretching, CH(3) umbrella, C = O stretching and CH(3) stretching modes have a significant effect on odor quality. In fact, the frequency shifts of the C-C stretching and C = O stretching modes, as well as CH(3) umbrella and CH(3) symmetric stretching modes, exhibit different behaviors in the PCA loadings plot. A large frequency shift in the CH(3) symmetric stretching mode is associated with the sweet-roasted odor category and separates this from the acid odor category. A large frequency shift of the C-C stretching mode describes the roasted and oily-popcorn odor categories, and separates these from the buttery and acid odor categories. PMID:21952829

Treesuwan, Witcha; Hirao, Hajime; Morokuma, Keiji; Hannongbua, Supa

2012-05-01

314

Inertia-Wheel Vibration-Damping System  

NASA Technical Reports Server (NTRS)

Proposed electromechanical system would damp vibrations in large, flexible structure. In active vibration-damping system motors and reaction wheels at tips of appendages apply reaction torques in response to signals from accelerometers. Velocity signal for vibrations about one axis processes into control signal to oppose each of n vibrational modes. Various modes suppressed one at a time. Intended primarily for use in spacecraft that has large, flexible solar panels and science-instrument truss assembly, embodies principle of control interesting in its own right and adaptable to terrestrial structures, vehicles, and instrument platforms.

Fedor, Joseph V.

1990-01-01

315

Bubble formation occurs in insulin pumps in response to changes in ambient temperature and atmospheric pressure but not as a result of vibration  

PubMed Central

Introduction Bubble formation in insulin pump giving sets is a common problem. We studied change in temperature, change in atmospheric pressure, and vibration as potential mechanisms of bubble formation. Methods 5 Animas 2020 pumps with 2?mL cartridges and Inset II infusion systems, 5 Medtronic Paradigm pumps with 1.8?mL cartridge and Quickset and 3 Roche Accu-chek pumps with 3.15?mL cartridges were used. Temperature study: insulin pumps were exposed to a temperature change from 4°C to 37°C. Pressure study: insulin pumps were taken to an altitude of 300?m. Vibration study: insulin pumps were vigorously shaken. All were observed for bubble formation. Results Bubble formation was observed with changes in temperature and atmospheric pressure. Bubble formation did not occur with vibration. Discussion Changes in insulin temperature and atmospheric pressure are common and may result in bubble formation. Vibration may distribute bubbles but does not cause bubble formation.

Lopez, Prudence E; King, Bruce R; Goss, Peter W; Chockalingam, Ganesh

2014-01-01

316

Estimates of auditory filter phase response at and below characteristic frequency (L)  

NASA Astrophysics Data System (ADS)

Animal studies in basal cochlear regions have shown that basilar-membrane phase curvature (or rate of change of group delay with frequency) is negative around characteristic frequency (CF), but near zero well below CF. This study examined whether psychophysical masking experiments in humans show the same difference between on- and off-CF phase curvature. Masked thresholds were measured for a 2-kHz signal in the presence of harmonic tone complex maskers with a fundamental frequency of 100 Hz, band-limited between 200 and 1400 Hz (off-frequency masker) or between 1400 and 2600 Hz (on-frequency masker). The results from four normal-hearing listeners are consistent with predictions from animal physiological data: negative phase curvature is found for the on-frequency masker, whereas the phase curvature for the off-frequency masker is near zero. The method and results provide a strong test for the temporal response of computational models of human cochlear filtering. .

Oxenham, Andrew J.; Ewert, Stephan D.

2005-04-01

317

Dynamic response characteristics of a circulation control rotor model pneumatic system  

NASA Technical Reports Server (NTRS)

Numerical and experimental simulation of unsteady airflow through the control valve and slotted air duct of a circulation control rotor is described. The numerical analysis involves the solution of the quasi-one-dimensional compressible fluid-dynamic equations in the blade air duct together with the coupled isentropic flow equations for flow into the blade through the valve and out of the blade through the Coanda slot. Numerical solutions are compared with basic experimental results obtained for a mockup of a circulation control rotor and its pneumatic valving system. The pneumodynamic phenomena that were observed are discussed with particular emphasis on the characteristic system time lags associated with the response of the flow variables to transient and periodic control valve inputs.

Watkins, C. B.; Reader, K. R.; Dutta, S. K.

1985-01-01

318

CHARADE: A characteristic code for calculating rate-dependent shock-wave response  

SciTech Connect

In this report we apply spatially one-dimensional methods and simple shock-tracking techniques to the solution of rate-dependent material response under flat-plate-impact conditions. This method of solution eliminates potential confusion of material dissipation with artificial dissipative effects inherent in finite-difference codes, and thus lends itself to accurate calculation of elastic-plastic deformation, shock-to-detonation transition in solid explosives, and shock-induced structural phase transformation. Equations are presented for rate-dependent thermoelastic-plastic deformation for (100) planar shock-wave propagation in materials of cubic symmetry (or higher). Specific numerical calculations are presented for polycrystalline copper using the mechanical threshold stress model of Follansbee and Kocks with transition to dislocation drag. A listing of the CHARADE (for characteristic rate dependence) code and sample input deck are given. 26 refs., 11 figs.

Johnson, J.N.; Tonks, D.L.

1991-01-01

319

Actively controlled vibration welding system and method  

DOEpatents

A vibration welding system includes a controller, welding horn, an active material element, and anvil assembly. The assembly may include an anvil body connected to a back plate and support member. The element, e.g., a piezoelectric stack or shape memory alloy, is positioned with respect to the assembly. The horn vibrates in a desirable first direction to form a weld on a work piece. The element controls any vibrations in a second direction by applying calibrated response to the anvil body in the second direction. A method for controlling undesirable vibrations in the system includes positioning the element with respect to the anvil assembly, connecting the anvil body to the support member through the back plate, vibrating the horn in a desirable first direction, and transmitting an input signal to the element to control vibration in an undesirable second direction.

Cai, Wayne W.; Kang, Bongsu; Tan, Chin-An

2013-04-02

320

Surface Acoustic Wave (SAW) Vibration Sensors  

PubMed Central

In the paper a feasibility study on the use of surface acoustic wave (SAW) vibration sensors for electronic warning systems is presented. The system is assembled from concatenated SAW vibration sensors based on a SAW delay line manufactured on a surface of a piezoelectric plate. Vibrations of the plate are transformed into electric signals that allow identification of the sensor and localization of a threat. The theoretical study of sensor vibrations leads us to the simple isotropic model with one degree of freedom. This model allowed an explicit description of the sensor plate movement and identification of the vibrating sensor. Analysis of frequency response of the ST-cut quartz sensor plate and a damping speed of its impulse response has been conducted. The analysis above was the basis to determine the ranges of parameters for vibrating plates to be useful in electronic warning systems. Generally, operation of electronic warning systems with SAW vibration sensors is based on the analysis of signal phase changes at the working frequency of delay line after being transmitted via two circuits of concatenated four-terminal networks. Frequencies of phase changes are equal to resonance frequencies of vibrating plates of sensors. The amplitude of these phase changes is proportional to the amplitude of vibrations of a sensor plate. Both pieces of information may be sent and recorded jointly by a simple electrical unit. PMID:22247694

Filipiak, Jerzy; Solarz, Lech; Steczko, Grzegorz

2011-01-01

321

Noncontact Electromagnetic Vibration Source  

NASA Technical Reports Server (NTRS)

Metal aircraft skins scanned rapidly in vibration tests. Relatively simple combination of permanent magnets and electromagnet serves as noncontact vibration source for nondestructive testing of metal aircraft skins. In test, source excites vibrations, and vibration waveforms measured, then analyzed for changes in resonances signifying cracks and other flaws.

Namkung, Min; Fulton, James P.; Wincheski, Buzz A.

1994-01-01

322

Boundary spanning by nurse managers: effects of managers' characteristics and scope of responsibility on teamwork.  

PubMed

Increasing role complexity has intensified the work of managers in supporting healthcare teams. This study examined the influence of front-line managers' characteristics and scope of responsibility on teamwork. Scope of responsibility considers the breadth of the manager's role. A descriptive, correlational design was used to collect cross-sectional survey and administrative data in four acute care hospitals. A convenience sample of 754 staff completed the Relational Coordination Scale as a measure of teamwork that focuses on the quality of communication and relationships. Nurses (73.9%), allied health professionals (14.7%) and unregulated staff (11.7%) worked in 54 clinical areas, clustered under 30 front-line managers. Data were analyzed using hierarchical linear modelling. Leadership practices, clinical support roles and compressed operational hours had positive effects on teamwork. Numbers of non-direct report staff and areas assigned had negative effects on teamwork. Teamwork did not vary by span, managerial experience, worked hours, occupational diversity or proportion of full-time employees. Large, acute care teaching hospitals can enable managers to foster teamwork by enhancing managers' leadership practices, redesigning the flow or reporting structure for non-direct reports, optimizing managerial hours relative to operational hours, allocating clinical support roles, reducing number of areas assigned and, potentially, introducing co-manager models. PMID:25073056

Meyer, Raquel M; O'Brien-Pallas, Linda; Doran, Diane; Streiner, David; Ferguson-Paré, Mary; Duffield, Christine

2014-06-01

323

Assessing the Value of Regulation Resources Based on Their Time Response Characteristics  

SciTech Connect

Fast responsive regulation resources are potentially more valuable as a power system regulation resource (more efficient) because they allow applying controls at the exact moment and in the exact amount as needed. Faster control is desirable because it facilitates more reliable compliance with the NERC Control Performance Standards at relatively lesser regulation capacity procurements. The current California ISO practices and markets do not provide a differentiation among the regulation resources based on their speed of response (with the exception of some minimum ramping capabilities). Some demand response technologies, including some generation and energy storage resources, can provide quicker control actions. California ISO practices and markets could be updated to welcome more fast regulation resources into the California ISO service area. The project work reported in this work was pursuing the following objectives: • Develop methodology to assess the relative value of generation resources used for regulation and load following California ISO functions • This assessment should be done based on physical characteristics including the ability to quickly change their output following California ISO signals • Evaluate what power is worth on different time scales • Analyze the benefits of new regulation resources to provide effective compliance with the mandatory NERC Control Performance Standards • Evaluate impacts of the newly proposed BAAL and FRR standards on the potential value of fast regulation and distributed regulation resources • Develop a scope for the follow-up projects to pave a road for the new efficient types of balancing resources in California. The work included the following studies: • Analysis of California ISO regulating units characteristics • California ISO automatic generation system (AGC) analysis • California ISO regulation procurement and market analysis • Fast regulation efficiency analysis • Projection of the California ISO load following and regulation requirements into the future • Value of fast responsive resources depending on their ramping capability • Potential impacts of the balancing authority area control error limit (BAAL), which is a part of the newly proposed NERC standard “Balancing Resources and Demand” • Potential impacts of the Western Electricity Coordinating Council (WECC) frequency responsive reserve (FRR) standard • Recommendations for the next phase of the project. The following main conclusions and suggestions for the future have been made: • The analysis of regulation ramping requirements shows that the regulation system should be able to provide ramps of at least 40-60 MW per minute for a period up to 6 minutes. • Evaluate if changes are needed in the California ISO AGC system to effectively accommodate new types of fast regulation resources and minimize the California ISO regulation procurement. • California ISO may consider creating better market opportunities for and incentives for fast responsive resources. • An additional study of low probability high ramp events can be recommended to the California ISO. • The California ISO may be willing to consider establishing a more relaxed target CPS2 compliance level. • A BAAL-related study can be recommended for the California ISO as soon as more clarity is achieved concerning the actual enforcement of the BAAL standard and its numerical values for the California ISO. The study may involve an assessment of advantages of the distributed frequency-based control for the California ISO system. The market-related issues that arise in this connection can be also investigated. • A FRR-related study can be recommended for the California ISO as soon as more clarity is achieved concerning the actual enforcement of the FRR standard and its numerical values for the California ISO.

Makarov, Yuri V.; Lu, Shuai; Ma, Jian; Nguyen, Tony B.

2008-06-01

324

Using response characteristics of neutron measurement devices to improve neutron dosimetry  

SciTech Connect

Recent administrative restrictions on personnel dose equivalent have resulted in increased pressure to more accurately report the neutron component without the traditional conservative added factors which sometimes inflate the reported values. Improvements include a new albedo neutron dosimeter which is capable of some limited energy discrimination. Also, additional emphasis has been placed on improving field measurements using traditional survey instrumentation and specialized spectroscopic techniques such as tissue equivalent proportional counters, Bonner spheres, and a modified 9 inches to 3 inches ratio technique. Improvements in these techniques along with a better understanding of the response of the TLD system have resulted in substantial reduction in the reported dose equivalent by improving the accuracy of the dosimeter system. The response characteristics of the TLD system and other instrumentation are obtained through modeling with the Monte Carlo code MCNP-4A. Neutron fields in work-areas are initially characterized with Bonner spheres. Routine updates are accomplished using a modified 9 inches to 3 inches ratio technique. These measurements are then used to predict the response of the TLD system when worn in that area. Correction curves are derived for the principal spectrum with various fractions of moderated or reflected neutrons. Work assignments are tracked through a database systems which is used to determine the principal spectrum that results in the neutron dose equivalent. The energy discrimination capability of the TLD system is used with the correction curve to derive an average correction appropriate to the readings of the dosimeter thus giving an energy corrected dose equivalent for the individual.

Casson, W.H.; Hsu, H.H.; Hoffman, J.M. [and others

1995-12-01

325

Investigation on the frequency response characteristics of an instrument for laser vibrometry and laser displacementmetry  

NASA Astrophysics Data System (ADS)

This paper proposes the new technique for the frequency response characterization of the laser vibrometry or the laser displacementmetry, where the optical interference is the working principle. In order to investigate the frequency response of laser vibrometers or laser displacement meters, the surface of high speed translational motion with the broad frequency bandwidth is absolutely required. That motion is materialized by the reflection of an elastic pulse propagating in a metal bar. A projectile made of aluminum is accelerated by the pressurized air and impinges on one end surface of the bar. The elastic wave is generated by the collision and propagates in the bar axis direction and reflects at the other end surface of the bar. The bar is supported by four steel bearing balls which are placed on the V-shaped grooves. The motion of the end surface can be considered to be in plain based on the numerical calculation. The surface is measured simultaneously using the reference laser interferometer developed in NRLM and a laser displacement meter based on the heterodyne technique (Hoshin Electronics HS-1100). HS-1100 uses the real time fringe counting technique. The reference interferometer, on the other hand uses a transient recorder (Tektronix RTD-710) which stores all of the interference signals during the elastic pulse reflection. The analysis and the wave form calculation based on the phase analysis is done after the experiment, leading to the broad frequency bandwidth. The comparison in the frequency domain using Fast Fourier Transform provides the frequency response characteristics of the tested laser displacement meter. It turned out that bandwidth of HS-1100 was up to 20 kHz, though the design value was 100 kHz.

Umeda, Akira; Ueda, Kazunaga

1996-09-01

326

Passively damped vibration welding system and method  

DOEpatents

A vibration welding system includes a controller, welding horn, an anvil, and a passive damping mechanism (PDM). The controller generates an input signal having a calibrated frequency. The horn vibrates in a desirable first direction at the calibrated frequency in response to the input signal to form a weld in a work piece. The PDM is positioned with respect to the system, and substantially damps or attenuates vibration in an undesirable second direction. A method includes connecting the PDM having calibrated properties and a natural frequency to an anvil of an ultrasonic welding system. Then, an input signal is generated using a weld controller. The method includes vibrating a welding horn in a desirable direction in response to the input signal, and passively damping vibration in an undesirable direction using the PDM.

Tan, Chin-An; Kang, Bongsu; Cai, Wayne W.; Wu, Tao

2013-04-02

327

Characteristics of the nuclear magnetic resonance logging response in fracture oil and gas reservoirs  

NASA Astrophysics Data System (ADS)

Fracture oil and gas reservoirs exist in large numbers. The accurate logging evaluation of fracture reservoirs has puzzled petroleum geologists for a long time. Nuclear magnetic resonance (NMR) logging is an effective new technology for borehole measurement and formation evaluation. It has been widely applied in non-fracture reservoirs, and good results have been obtained. But its application in fracture reservoirs has rarely been reported in the literature. This paper studies systematically the impact of fracture parameters (width, number, angle, etc), the instrument parameter (antenna length) and the borehole condition (type of drilling fluid) on NMR logging by establishing the equation of the NMR logging response in fracture reservoirs. First, the relationship between the transverse relaxation time of fluid-saturated fracture and fracture aperture in the condition of different transverse surface relaxation rates was analyzed; then, the impact of the fracture aperture, dip angle, length of two kinds of antennas and mud type was calculated through forward modeling and inversion. The results show that the existence of fractures affects the NMR logging; the characteristics of the NMR logging response become more obvious with increasing fracture aperture and number of fractures. It is also found that T2 distribution from the fracture reservoir will be affected by echo spacing, type of drilling fluids and length of antennas. A long echo spacing is more sensitive to the type of drilling fluid. A short antenna is more effective for identifying fractures. In addition, the impact of fracture dip angle on NMR logging is affected by the antenna length.

Xiao, Lizhi; Li, Kui

2011-04-01

328

Effects of deafness and cochlear implant use on temporal response characteristics in cat primary auditory cortex.  

PubMed

We have previously shown that neonatal deafness of 7-13 months duration leads to loss of cochleotopy in the primary auditory cortex (AI) that can be reversed by cochlear implant use. Here we describe the effects of a similar duration of deafness and cochlear implant use on temporal processing. Specifically, we compared the temporal resolution of neurons in AI of young adult normal-hearing cats that were acutely deafened and implanted immediately prior to recording with that in three groups of neonatally deafened cats. One group of neonatally deafened cats received no chronic stimulation. The other two groups received up to 8 months of either low- or high-rate (50 or 500 pulses per second per electrode, respectively) stimulation from a clinical cochlear implant, initiated at 10 weeks of age. Deafness of 7-13 months duration had no effect on the duration of post-onset response suppression, latency, latency jitter, or the stimulus repetition rate at which units responded maximally (best repetition rate), but resulted in a statistically significant reduction in the ability of units to respond to every stimulus in a train (maximum following rate). None of the temporal response characteristics of the low-rate group differed from those in acutely deafened controls. In contrast, high-rate stimulation had diverse effects: it resulted in decreased suppression duration, longer latency and greater jitter relative to all other groups, and an increase in best repetition rate and cut-off rate relative to acutely deafened controls. The minimal effects of moderate-duration deafness on temporal processing in the present study are in contrast to its previously-reported pronounced effects on cochleotopy. Much longer periods of deafness have been reported to result in significant changes in temporal processing, in accord with the fact that duration of deafness is a major factor influencing outcome in human cochlear implantees. PMID:24933111

Fallon, James B; Shepherd, Robert K; Nayagam, David A X; Wise, Andrew K; Heffer, Leon F; Landry, Thomas G; Irvine, Dexter R F

2014-09-01

329

Linear vibration analysis of rotating wind-turbine blade  

Microsoft Academic Search

In the wind-turbine design, linear vibration analysis of the wind-turbine blade should be performed to get vibratory characteristics and to avoid structural resonance. EOM (equations of motion) for the blade are derived and vibratory characteristics of a rotating blade are observed and discussed in this work. Linear vibration analysis requires the linearized EOM with DOF (degree of freedom). For the

Jung-Hun Park; Hyun-Yong Park; Seok-Yong Jeong; Sang-Il Lee; Young-Ho Shin; Jong-Po Park

2010-01-01

330

[Effects of pikamilon on the brain water-electrolyte balance and in models of responses to the noise and vibration exposure, and their combination with motion sickness].  

PubMed

Electric impedance measurements on awake rabbits with electrodes implanted into cortex, thalamus, and hypothalamus showed that modeling of the noise and general (wide-band) vibration, as well as their combination with sea-sickness action, leads to disturbances in the aqueous-electrolyte balance in brain. This is manifested by extracellular and (less pronounced) intracellular edema development. Picamilon administration (10 mg/kg, i.v.) completely prevented development of the vibration-induced intracellular edema and markedly reduced the development of damage in all other cases studied. PMID:11109535

Sapegin, I D

2000-01-01

331

Transmission Conditions of Vibration Stresses to Welding Specimens of Ultrasonic Plastic Welding using Various Two-Vibration-System Equipments  

NASA Astrophysics Data System (ADS)

Ultrasonic plastic welding is applied for welding various thermoplastic materials and is widely used in various industrial fields. The two-vibration-system welding method and a high frequency equipment are effective in improving the welding characteristics. A high frequency 90 kHz system can weld plastic sheets under a 1/3 velocity amplitude as compared with that of a low 27 kHz system, but it is difficult to weld large specimens successfully because a high frequency vibration stress cannot be transmitted uniformly due to the stress relaxation effect by the small vibration displacement. To improve the direct welding characteristics, three types of two-vibration-system ultrasonic welding equipments using linear vibration loci of (1) 90 kHz and 27 kHz longitudinal vibration systems, (2) 90 kHz longitudinal and 20 kHz torsional vibration systems, and elliptical vibration loci of (3) 27 kHz complex vibration systems are studied. Transmission conditions of the vibration stresses are measured by pressure sensitive films (Prescale) which are inserted between the plastic sheets. It was shown that a high frequency vibration stress with a small displacement amplitude may be induced uniformly in the welding specimens by combining a low frequency vibration with large displacement amplitude. These welding systems are effectively used to join plastic sheets successfully.

Tsujino, Jiromaru; Uchida, Takako; Ohkusa, Kunifumi; Adachi, Tatsuya; Ueoka, Tetsugi

1998-05-01

332

[The response characteristics of TM image reflectance to the arid region of soil moisture].  

PubMed

The response characteristics of TM image to the soil moisture in the Tarim River are the research object. Selected the image spectrum (R), spectrum reciprocal (1/R), the logarithm of reciprocal spectrum lg(1/R) and removal normalized difference vegetation index (R(c)) of four spectral index were selected to establish the soil moisture content prediction model, the variance test was used to validate the model significance, the model accuracy level was divided by the posterior variance examination. The results showed that: the model accuracy of the logarithm of reciprocal spectrum lg(1/R) prediction of soil moisture is the highest, and achieved a good level for the monitoring of soil moisture content (0 - 30 cm). The model accuracy of the spectral (R) and spectral reciprocal (1/R) prediction of soil moisture is lower than logarithm of reciprocal spectrum with only the individual layers (0-30, 0-50 cm, etc.) reaching the qualified level or narrouly qualified level. The model accuracy of the removal normalized difference vegetation index (R(c)) prediction of soil moisture is the lowest. Besides, the best prediction depth of every model is the depth of 0-30 cm, and if the soil depth is too deep or too shallow, the prediction accuracy will decrease. PMID:22250564

Li, Bao-Fu; Li, Wei-Hong; Cao, Zhi-Chao

2011-10-01

333

Linear response characteristics of time-dependent time fractional Fokker–Planck equation systems  

NASA Astrophysics Data System (ADS)

The time fractional Fokker–Planck equation approach is an important tool for modeling subdiffusion. When the external field is time modulated, two types of time-dependent time fractional Fokker–Planck equations have been proposed, both reduced to the same time-dependent time fractional Fokker–Planck equation when the external field is time uncorrelated. The first type is strictly deduced as the continuous limit of the continuous time random walk with time modulated Boltzmann jumping weight, while the second type is derived by ideally assuming that the jump probabilities can be evaluated at the start of the waiting time prior to jumping. For the first time we obtain the linear response characteristic for the first type of the time fractional Fokker–Planck equation systems, and for a comparison we revisit the corresponding result for the second type of the time fractional Fokker–Planck equation systems, and the similarity and difference between them is discussed with an application example. The investigation not only helps in understanding the competition between subdiffusion and time-dependent modulation, but also has significance in accessing the spectral properties of spontaneous fluctuation and the linear dynamic susceptibility of external perturbation in subdiffusive processes.

Kang, Yan-Mei; Jiang, Yao-Lin; Yong, Xie

2014-11-01

334

Life-history traits and landscape characteristics predict macro-moth responses to forest fragmentation.  

PubMed

How best to manage forest patches, mitigate the consequences of forest fragmentation, and enable landscape permeability are key questions facing conservation scientists and managers. Many temperate forests have become increasingly fragmented, resulting in reduced interior forest habitat, increased edge habitats, and reduced connectivity. Using a citizen science landscape-scale mark-release-recapture study on 87 macro-moth species, we investigated how both life-history traits and landscape characteristics predicted macro-moth responses to forest fragmentation. Wingspan, wing shape, adult feeding, and larval feeding guild predicted macro-moth mobility, although the predictive power of wingspan and wing shape depended on the species' affinity to the forest. Solitary trees and small fragments functioned as "stepping stones," especially when their landscape connectivity was increased, by being positioned within hedgerows or within a favorable matrix. Mobile forest specialists were most affected by forest fragmentation: despite their high intrinsic dispersal capability, these species were confined mostly to the largest of the forest patches due to their strong affinity for the forest habitat, and were also heavily dependent on forest connectivity in order to cross the agricultural matrix. Forest fragments need to be larger than five hectares and to have interior forest more than 100 m from the edge in order to sustain populations of forest specialists. Our study provides new insights into the movement patterns of a functionally important insect group, with implications for the landscape-scale management of forest patches within agricultural landscapes. PMID:23951712

Slade, Eleanor M; Merckx, Thomas; Riutta, Terhi; Bebber, Daniel P; Redhead, David; Riordan, Philip; Macdonald, David W

2013-07-01

335

Fermentation characteristics of Mortierella alpina in response to different nitrogen sources.  

PubMed

The fermentation characteristics of Mortierella alpina were investigated in response to various nitrogen sources. Influences on nitrogen source and glucose uptake rate, mycelial morphology of M. alpina, and pH of medium in relation to different nitrogen sources were discussed. Effects of different nitrogen sources on cell growth, fatty acid composition, arachidonic acid (ARA), and total lipid concentration were also evaluated. It revealed that the maximum nitrogen source uptake ratio was obtained when corn steep liquor was used as nitrogen source. When yeast extract was used as the sole nitrogen source, glucose was completely exhausted at the end of fermentation. The maximum dry cell weight obtained from medium with yeast extract as nitrogen source had the highest total lipid concentration. Sodium nitrate was the favorable nitrogen source for ARA accumulation, and the highest ARA percentage in total fatty acids was obtained, 35.9%. Urea was identified as the favorable nitrogen source for ARA production, the highest ARA concentration obtained from urea was 5.8 g/l. Compared with inorganic nitrogen sources, organic nitrogen compounds are favorable for both cell growth and total lipids accumulation. PMID:21336613

Lu, Jinmiao; Peng, Chao; Ji, Xiao-Jun; You, Jiangying; Cong, Leilei; Ouyang, Pingkai; Huang, He

2011-08-01

336

The derivation of species response curves with Gaussian logistic regression is sensitive to sampling intensity and curve characteristics  

Microsoft Academic Search

We investigated quantitatively the sensitivity of plant species response curves to sampling characteristics (number of plots, occurrence and frequency of species), along a simulated pH gradient. We defined 54 theoretical unimodal response curves, issued from combinations of six values for optimum (opt=3, 4, …, 8), three values for tolerance (tol=0.5, 1.0, and 1.5, sensu ter Braak and Looman [ter Braak,

Christophe Coudun; Jean-Claude Gégout

2006-01-01

337

The acceptability of railway induced vibration in residential environments.  

PubMed

The aim of the study presented in this paper is to investigate the use of self-reported acceptability for assessing the human response to environmental vibration in residential environments. The human response to environmental stressors such as noise and vibration is often expressed in terms of exposure-response relationships that describe annoyance as a function of the magnitude of the vibration. These relationships are often the basis of noise and vibration policy and the setting of limit values. This paper takes a different approach by expressing exposure-response relationships for vibration in terms of self-reported acceptability. It is argued that exposure-response relationships expressing acceptability as a function of vibration exposure will complement existing relationships for annoyance in future policy decisions regarding environmental vibration. The results presented in this paper are derived from data collected through a large scale (N = 1431) socio-vibration survey conducted in the United Kingdom, the aim of which was to derive exposure-response relationships for vibration in residential environments. The sources of vibration considered are railways and construction. PMID:25235566

Woodcock, James; Peris, Eulalia; Sica, Gennaro; Sharp, Calum; Moorhouse, Andy T; Waddington, David C

2014-04-01

338

A comparison of power output from linear and nonlinear kinetic energy harvesters using real vibration data  

NASA Astrophysics Data System (ADS)

The design of vibration energy harvesters (VEHs) is highly dependent upon the characteristics of the environmental vibrations present in the intended application. VEHs can be linear resonant systems tuned to particular frequencies or nonlinear systems with either bistable operation or a Duffing-type response. This paper provides detailed vibration data from a range of applications, which has been made freely available for download through the Energy Harvesting Network’s online data repository. In particular, this research shows that simulation is essential in designing and selecting the most suitable vibration energy harvester for particular applications. This is illustrated through C-based simulations of different types of VEHs, using real vibration data from a diesel ferry engine, a combined heat and power pump, a petrol car engine and a helicopter. The analysis shows that a bistable energy harvester only has a higher output power than a linear or Duffing-type nonlinear energy harvester with the same Q-factor when it is subjected to white noise vibration. The analysis also indicates that piezoelectric transduction mechanisms are more suitable for bistable energy harvesters than electromagnetic transduction. Furthermore, the linear energy harvester has a higher output power compared to the Duffing-type nonlinear energy harvester with the same Q factor in most cases. The Duffing-type nonlinear energy harvester can generate more power than the linear energy harvester only when it is excited at vibrations with multiple peaks and the frequencies of these peaks are within its bandwidth. Through these new observations, this paper illustrates the importance of simulation in the design of energy harvesting systems, with particular emphasis on the need to incorporate real vibration data.

Beeby, Stephen P.; Wang, Leran; Zhu, Dibin; Weddell, Alex S.; Merrett, Geoff V.; Stark, Bernard; Szarka, Gyorgy; Al-Hashimi, Bashir M.

2013-07-01

339

Vibrational stiffness of an atomic lattice  

NASA Astrophysics Data System (ADS)

A model is presented to estimate the characteristic vibrational stiffness of an atomic lattice, given the pairwise interaction potential of the constituent atom. Unlike nearest-neighbor approaches (e.g., Slater or Dugdale and MacDonald), the vibrational stiffness is shown to be distinct from the bulk (i.e., volumetric) stiffness. This vibrational stiffness implies a characteristic vibrational frequency of the lattice that varies with the lattice spacing, which is used to infer the Grueneisen function of the lattice. Because non-nearest lattice neighbors are accounted for, the equations are expressed in terms of triple summations of the pairwise potential. However, an analytical fit to these triple summations has been developed. Furthermore, the analytical form calibrates to a range of cold- and shock-compression data, resulting in an analytical frequency-based equation of state (EOS) for crystalline solids.

Segletes, Steven B.

2000-04-01

340

Ambient Vibration Testing for Story Stiffness Estimation of a Heritage Timber Building  

PubMed Central

This paper investigates dynamic characteristics of a historic wooden structure by ambient vibration testing, presenting a novel estimation methodology of story stiffness for the purpose of vibration-based structural health monitoring. As for the ambient vibration testing, measured structural responses are analyzed by two output-only system identification methods (i.e., frequency domain decomposition and stochastic subspace identification) to estimate modal parameters. The proposed methodology of story stiffness is estimation based on an eigenvalue problem derived from a vibratory rigid body model. Using the identified natural frequencies, the eigenvalue problem is efficiently solved and uniquely yields story stiffness. It is noteworthy that application of the proposed methodology is not necessarily confined to the wooden structure exampled in the paper. PMID:24227999

Min, Kyung-Won; Kim, Junhee; Park, Sung-Ah; Park, Chan-Soo

2013-01-01

341

Item Response Characteristics in Attitude and Personality Measurement: A Reaction to L. G. Roper'S 'The Great Response-Style Myth'.  

National Technical Information Service (NTIS)

However defined, response style is not a myth. Responses to personality items are the result of, among other things, (a) item content (b) social desirability of this content, (c) form in which this content is stated, proportion of each form of statement i...

E. A. Rundquist

1967-01-01

342

Vibration fatigue analysis and multi-axial effect in testing of aerospace structures  

NASA Astrophysics Data System (ADS)

The work reported in this paper compared the fatigue damage accumulated under uni-axial loading (a procedure promoted by the vibration testing standards) to that induced by multi-axial loading. The comparison was performed for a helicopter structural element (the flare dispenser bracket of the self-defensive system's Chaff), which is exposed to the particular combination of wide-band random with sinusoidal vibrations, which is characteristic to the helicopter dynamic environment. The evaluation of the fatigue damage induced by these loads requires the calculation or measurement of the structure's dynamic response in terms of stresses or strains, and the application of the appropriate methodology to this response. In this work, dynamic response was calculated in the frequency domain based on the relations between the power spectral density matrixes of the excitations to that of the responses for a linear system. The transfer matrix that relates the excitation to the responses was evaluated numerically. The power spectral densities of the responses evaluated at different locations on the structure were used in the determination of the responses' statistics (the counting of the loading cycles), which, combined with an appropriate physics of failure model (fatigue model), enabled the evaluation of the accumulated fatigue damage. The uni-axial-induced fatigue was evaluated from vibration tests of the kind promoted by military standards (it is assumed that axis-by-axis loading is cumulatively equal to multi-axial loading), and compared to that evaluated by analysis for the multi-axial loading. Also a numerical comparison of the effects of the two kinds of loading was performed. The results showed that the error of uni-axial testing varied for a wide range of parameters. The work led to the conclusion that simultaneous multi-axis vibration testing can improve significantly the laboratory's vibration simulation realism.

Aykan, Murat; Çelik, Mehmet

2009-04-01

343

A method for analyzing vibration power absorption density in human fingertip  

NASA Astrophysics Data System (ADS)

In the current study, we hypothesize that the vibration power absorption density (VPAD) is a good measure for the vibration exposure intensity of the soft tissues of the fingers. In order to calculate the VPAD at a fingertip, we proposed a hybrid modeling approach, which combines a 2D finite element (FE) model with a lumped parameter model. Whereas the lumped components are used to represent the global biodynamic characteristics of the hand-arm system, the FE component is used to predict the detailed stresses, strains, and VPAD in the fingertip. The lumped parameters are determined by using the vibration transmissibilities measured at the fingertip, while the material parameters of the soft and hard tissues of the FE model are adopted from the published experimental data. The proposed model was applied to predict the distributions of dynamic displacement, velocity, and VPAD in the soft tissues of the fingertip. Furthermore, we have derived the frequency weighting based on the VPAD of the soft tissue. The preliminary analysis indicated that the VPAD-based frequency weighting is substantially different from the ISO weighting in that the ISO frequency weighting emphasizes the effect of the vibration at frequencies lower than 25 Hz whereas the VPAD-based weighting generally emphasizes the resonant responses of the finger. Our analysis indicated that the VPAD-based weighting was fairly consistent with the finger surface vibration transmissibility at frequencies greater than the first resonance, suggesting that the finger surface transmissibility may be used as an alternative frequency weighting for assessing the finger vibration exposure. The proposed method provides a practical and efficient tool to simulate the detailed biodynamic responses of a complex biological system to vibration.

Wu, John Z.; Dong, Ren G.; Welcome, Daniel E.; Xu, Xueyan S.

2010-12-01

344

Biocompatibility, Inflammatory Response, and Recannalization Characteristics of Nonradioactive Resin Microspheres: Histological Findings  

SciTech Connect

Intra-arterial radiotherapy with yttrium-90 microspheres (radioembolization) is a therapeutic procedure exclusively applied to the liver that allows the direct delivery of high-dose radiation to liver tumors, by means of endovascular catheters, selectively placed within the tumor vasculature. The aim of the study was to describe the distribution of spheres within the precapillaries, inflammatory response, and recannalization characteristics after embolization with nonradioactive resin microspheres in the kidney and liver. We performed a partial embolization of the liver and kidney vessels in nine white pigs. The left renal and left hepatic arteries were catheterized and filled with nonradioactive resin microspheres. Embolization was defined as the initiation of near-stasis of blood flow, rather than total occlusion of the vessels. The hepatic circulation was not isolated so that the effects of reflux of microspheres into stomach could be observed. Animals were sacrificed at 48 h, 4 weeks, and 8 weeks, and tissue samples from the kidney, liver, lung, and stomach evaluated. Microscopic evaluation revealed clusters of 10-30 microspheres (15-30 {mu}m in diameter) in the small vessels of the kidney (the arciform arteries, vasa recti, and glomerular afferent vessels) and liver. Aggregates were associated with focal ischemia and mild vascular wall damage. Occlusion of the small vessels was associated with a mild perivascular inflammatory reaction. After filling of the left hepatic artery with microspheres, there was some evidence of arteriovenous shunting into the lungs, and one case of cholecystitis and one case of marked gastritis and ulceration at the site of arterial occlusion due to the presence of clusters of microspheres. Beyond 48 h, microspheres were progressively integrated into the vascular wall by phagocytosis and the lumen recannalized. Eight-week evaluation found that the perivascular inflammatory reaction was mild. Liver cell damage, bile duct injury, and portal space fibrosis were not observed. In conclusion, resin microspheres (15-30 {mu}m diameter) trigger virtually no inflammatory response in target tissues (liver and kidney). Clusters rather than individual microspheres were associated with a mild to moderate perivascular inflammatory reaction. There was no evidence of either a prolonged inflammatory reaction or fibrosis in the liver parenchyma following recannalization.

Bilbao, Jose I., E-mail: Jibilbao@unav.e [Clinica Universitaria de Navarra, Universidad de Navarra, Department of Radiology (Spain); Martino, Alba de [Universidad de Zaragoza, Department of Histology, School of Veterinary (Spain); Luis, Esther de; Diaz-Dorronsoro, Lourdes; Alonso-Burgos, Alberto; Martinez de la Cuesta, Antonio [Clinica Universitaria de Navarra, Universidad de Navarra, Department of Radiology (Spain); Sangro, Bruno [Clinica Universitaria de Navarra, Universidad de Navarra, Department of Internal Medicine (Liver Unit) (Spain); Garcia de Jalon, Jose A. [Universidad de Zaragoza, Department of Histology, School of Veterinary (Spain)

2009-07-15

345

Effects of Rearing Systems on Performance, Egg Characteristics and Immune Response in Two Layer Hen Genotype  

PubMed Central

White (Lohmann LSL) and Brown (ATAK-S) laying hens, were reared under organic and conventional cage rearing systems, and the effects of the rearing system on performance parameters, egg production, egg characteristics, and immune response were investigated. For this purpose, a total of 832 laying hens of two commercial hybrids, i.e., 416 white (Lohmann LSL) and 416 Brown (ATAK-S) layers, were used. The experiment lasted between 23 and 70 wk of age. In this study, the white layers yielded more eggs as compared to the brown layers in both organic and conventional production systems. Egg weight exhibited a similar pattern to that of laying performance. However, the total hen-housed egg number for the white birds in the organic system was fewer than that of white birds in the conventional cage facility; conversely, a contradictory tendency was observed for the brown birds. Livability of the white layers in the organic system was remarkably lower (14%) than that of the brown line, whereas the white line survived better (3.42%) than their brown counterparts in conventional cages. The feed conversion ratio of the white hens was markedly inferior in the organic system as compared to that of the white hens in the conventional system, whereas relatively lower deterioration was reported in brown layers when reared in an organic system. The organic production system increased egg albumen height and the Haugh unit in eggs of the brown layers. The yolk color score of organic eggs was lower than that of conventional eggs for both brown and white hens. The egg yolk ratio of eggs from white layers was found to be higher in organic eggs as compared to those obtained in the conventional system. All organic eggs had heavier shells than those produced in the conventional system. Eggs from brown layers had more protein content than eggs from white layers. Neither housing systems nor genotype influenced egg yolk cholesterol concentration. When compared to conventional eggs, n-3 fatty acid content was lower in organic eggs, and the n-6:n-3 ratio was higher in organic eggs. In conclusion, two hen genotypes showed different responses in terms of performance and egg quality to two different rearing systems. A commercial white strain produced more eggs with higher egg quality as compared to a native brown strain. The brown strain was found to have adapted well to organic production conditions when survival and total egg number was taken into consideration. PMID:25049597

Kucuky?lmaz, Kamil; Bozkurt, Mehmet; Herken, Emine Nur; C?nar, Mustafa; Catl?, Abdullah Ugur; Bintas, Erol; Coven, Fethiye

2012-01-01

346

Experimental Analysis of Steady-State Maneuvering Effects on Transmission Vibration Patterns Recorded in an AH-1 Cobra Helicopter  

NASA Technical Reports Server (NTRS)

Flight experiment was designed primarily to determine the extent to which steady-state maneuvers influence characteristic vibration patterns measured at the input pinion and output annulus gear locations of the main transmission. If results were to indicate that maneuvers systematically influence vibration patterns, more extensive studies would be planned to explore the response surface. It was also designed to collect baseline data for comparison with experimental data to be recorded at a later date from test stands at Glenn Research Center. Finally, because this was the first vibration flight study on the Cobra aircraft, considerable energy was invested in developing an in-flight recording apparatus, as well as exploring acceleration mounting methods, and generally learning about the overall vibratory characteristics of the aircraft itself.

Huff, Edward M.; Dzwonczyk, Mark; Norvig, Peter (Technical Monitor)

2000-01-01

347

Damper Of Small Vibrations  

NASA Technical Reports Server (NTRS)

Vibration damper has no rubbing parts. Thus eliminates even very small static frictional forces and therefore responds to and damps extremely low levels of vibration. Damper dissipates vibration by motion of piston in volume of silicone oil. Coaxial rigid shaft holds upper and lower bellows at constant length while piston vibrates up and down. Although volumes of upper and lower bellows change continually, total volume of bellows assembly stays same.

Davis, L. P.

1989-01-01

348

FREE VIBRATION OF HEATED EULER–BERNOULLI BEAMS WITH THERMAL POSTBUCKLING DEFORMATIONS  

Microsoft Academic Search

Based on the accurate geometrical nonlinear theory for Euler–Bernoulli beams, considering the coupling of the longitudinal and transverse motions, the harmonic responses of small vibration of uniformly heated beams with and without static thermal postbuckling deformations are presented by employing the numerical shooting technique. Characteristic curves of the lower order frequencies versus the temperature parameter are illustrated for pinned-pinned, fixed-fixed,

Shi-Rong Li; Zhao-Chun Teng; You-He Zhou

2004-01-01

349

Hermetically sealed vibration damper  

NASA Technical Reports Server (NTRS)

Simple fluidic vibration damper for installation at each pivotal mounting between gimbals isolates inertial measuring units from external vibration and other disruptive forces. Installation between each of the three gimbal axes can dampen vibration and shock in any direction while permitting free rotation of the gimbals.

Wheatley, D. G.

1969-01-01

350

Design of a non-traditional dynamic vibration absorber.  

PubMed

A non-traditional dynamic vibration absorber is proposed for the minimization of maximum vibration velocity response of a vibrating structure. Unlike the traditional damped absorber configuration, the proposed absorber has a linear viscous damper connecting the absorber mass directly to the ground instead of the main mass. Optimum parameters of the proposed absorber are derived based on the fixed-point theory for minimizing the maximum vibration velocity response of a single-degree-of-freedom system under harmonic excitation. The extent of reduction in maximum vibration velocity response of the primary system when using the traditional dynamic absorber is compared with that using the proposed one. Under the optimum tuning condition of the absorbers, it is proved analytically that the proposed absorber provides a greater reduction in maximum vibration velocity response of the primary system than the traditional absorber. PMID:19640019

Cheung, Y L; Wong, W O

2009-08-01

351

DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM  

SciTech Connect

The deep hard rock drilling environment induces severe vibrations into the drillstring, which can cause reduced rates of penetration (ROP) and premature failure of the equipment. The only current means of controlling vibration under varying conditions is to change either the rotary speed or the weight-on-bit (WOB). These changes often reduce drilling efficiency. Conventional shock subs are useful in some situations, but often exacerbate the problems. The objective of this project is development of a unique system to monitor and control drilling vibrations in a ''smart'' drilling system. This system has two primary elements: (1) The first is an active vibration damper (AVD) to minimize harmful axial, lateral and torsional vibrations. The hardness of this damper will be continuously adjusted using a robust, fast-acting and reliable unique technology. (2) The second is a real-time system to monitor drillstring vibration, and related parameters. This monitor adjusts the damper according to local conditions. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. The AVD is implemented in a configuration using magnetorheological (MR) fluid. By applying a current to the magnetic coils in the damper, the viscosity of the fluid can be changed rapidly, thereby altering the damping coefficient in response to the measured motion of the tool. Phase I of this program entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. Phase I of the project was completed by the revised end date of May 31, 2004. The objectives of this phase were met, and all prerequisites for Phase II have been completed.

Martin E. Cobern

2004-08-31

352

Vibration Testing of Stirling Power Convertors  

NASA Technical Reports Server (NTRS)

The NASA John H. Glenn Research Center (GRC) and the U.S. Department of Energy (DOE) are currently developing a high efficient, long life, free piston Stirling convertor for use as an advanced spacecraft power system for future NASA missions. As part of this development, a Stirling Technology Demonstrator Convertor (TDC), developed by Stirling Technology Company (STC) for DOE, was vibration tested at GRC s Structural Dynamics Laboratory (SDU7735) in November- December 1999. This testing demonstrated that the Stirling TDC is able to withstand the harsh random vibration (20 to 2000 Hertz) seen during a typical spacecraft launch and survive with no structural damage or functional power performance degradation, thereby enabling its usage in future spacecraft power systems. The Stirling Vibration Test Team at NASA GRC and STC personnel conducted tests on a single 55 electric watt TDC. The purpose was to characterize the TDC s structural response to vibration and determine if the TDC could survive the vibration criteria established by the Jet Propulsion Laboratory (JPL) for launch environments. The TDC was operated at full-stroke and full power conditions during the vibration testing. The TDC was tested in two orientations, with the direction of vibration parallel and perpendicular to the TDC s moving components (displacer and piston). The TDC successfully passed a series of sine and random vibration tests. The most severe test was a 12.3 Grms random vibration test (peak vibration level of 0.2 g2/Hz from 50 to 250 Hertz) with test durations of 3 minutes per axis. The random vibration test levels were chosen to simulate, with margin, the maximum anticipated launch vibration conditions. As a result of this very successful vibration testing and successful evaluations in other key technical readiness areas, the Stirling power system is now considered a viable technology for future application for NASA spacecraft missions. Possible usage of the Stirling power system would be to supply on- board electric spacecraft power for future NASA Deep-Space Missions, performing as an attractive alternative to Radioisotope Thermoelectric Generators (RTG). Usage of the Stirling technology is also being considered as the electric power source for future Mars rovers, whose mission profiles may exclude the use of photovoltaic power systems (such as exploring at high Martian latitudes or for missions of lengthy durations). GRC s Thermo-Mechanical Systems Branch (5490) provides Stirling technology expertise under a Space Act Agreement with the DOE. Additional vibration testing, by GRC s Structural Systems Dynamics Branch (7733, is planned to continue to demonstrate the Stirling power system s vibration capability as its technology and flight system designs progress.

Hughes, Bill; Goodnight, Thomas; McNelis, Mark E.; Suarez, Vicente J.; Schreiber, Jeff; Samorezov, Sergey

2003-01-01

353

Personal characteristics in college students' evaluations of business ethics and corporate social responsibility  

Microsoft Academic Search

A survey of 138 college students reveals an undergraduate major has a greater influence on corporate social responsibility than business ethics. Business students are no less ethical than nonbusiness students. Females are more ethical and socially responsible than males. Age is negatively related to one's Machiavellian orientation and positively related to negative attitudes about corporate efforts at social responsibility. The

Peter Arlow

1991-01-01

354

Random vibration control based on adaptive filter  

Microsoft Academic Search

The random vibration adaptive control method is presented based on the recursive least-squares (RLS) adaptive filter. The power spectral density (PSD) of drive signal is updated based on the off-line identification of frequency response function (FRF) in conventional random vibration control system. And the pseudo-random drive signal generated by the conventional time-frequency transformation has leakage between frequency resolutions. The control

Guangfeng Guan; Wei Xiong; Haitao Wang

2010-01-01

355

Optical vibration detection spectral analysis assembly and method for detecting vibration in an object of interest  

DOEpatents

A vibration detection assembly is described which includes an emitter of light which has object and reference beams, the object beam reflected off of a vibrating object of interest; and a photorefractive substance having a given response time and which passes the reflected object beam and the reference beam, the reference beam and the object beam interfering within the photorefractive substance to create a space charge field which develops within the response time of the photorefractive substance. 6 figs.

Hale, T.C.; Telschow, K.L.

1998-10-27

356

Optical vibration detection spectral analysis assembly and method for detecting vibration in an object of interest  

DOEpatents

A vibration detection assembly is described which includes an emitter of light which has object and reference beams, the object beam reflected off of a vibrating object of interest; and a photorefractive substance having a given response time and which passes the reflected object beam and the reference beam, the reference beam and the object beam interfering within the photorefractive substance to create a space charge field which develops within the response time of the photorefractive substance.

Hale, Thomas C. (Los Alamos, NM); Telschow, Kenneth L. (Idaho Falls, ID)

1998-01-01

357

Eggshell Cutter Using Ultrasonic Vibration  

NASA Astrophysics Data System (ADS)

An eggshell cutting apparatus which utilizes ultrasonic vibration was developed, replacing the conventional apparatus which uses an air cutter, to cut eggshells at the blunt end of eggs. Two ultrasonic vibration sources were used: one with longitudinal vibration only and the other with torsional vibration plus longitudinal vibration. Eggshell cutting experiments using these vibration sources were conducted. The eggshell cutting time sharply decreased with increasing longitudinal vibration amplitude as well as increasing input power. When the source with torsional vibration plus longitudinal vibration was used and the amplitude of longitudinal vibration was 12 ?m or less, the torsional vibration was effective for cutting eggshells. Furthermore, at the same input power, the eggshell cutting time by the source with longitudinal vibration only was shorter than that by the source with torsional vibration plus longitudinal vibration. When an egg was cut using the apparatus, there was essentially no cutting noise and the cut surface was smooth.

Miura, Hikaru

2003-05-01

358

Studies of physical characteristics and animal response to reconstituted sorghum grain  

E-print Network

date of reconstitution 35 Endosperm cells containing starch granules from dry grain (840X). 51 Endosperm cells containing starch granules from reconstituted grain (840X) 51 Starch granules from reconstituted grain (840X) 52 10 Reconstituted grain... physical characteristics of dry and reconstituted sorghum grain which may help to explain the mechanism of action in the reconstitution process. CHAPTER II REVIEW OF LITERATURE Structure and Characteristics of the Sor hum Grain Kernel The mature seed...

Florence, Harold Douglas

2012-06-07

359

Shear flow induced vibrations of long slender cylinders with a wake oscillator model  

NASA Astrophysics Data System (ADS)

A time domain model is presented to study the vibrations of long slender cylinders placed in shear flow. Long slender cylinders such as risers and tension legs are widely used in the field of ocean engineering. They are subjected to vortex-induced vibrations (VIV) when placed within a transverse incident flow. A three dimensional model coupled with wake oscillators is formulated to describe the response of the slender cylinder in cross-flow and in-line directions. The wake oscillators are distributed along the cylinder and the vortex-shedding frequency is derived from the local current velocity. A non-linear fluid force model is accounted for the coupled effect between cross-flow and in-line vibrations. The comparisons with the published experimental data show that the dynamic features of VIV of long slender cylinder placed in shear flow can be obtained by the proposed model, such as the spanwise average displacement, vibration frequency, dominant mode and the combination of standing and traveling waves. The simulation in a uniform flow is also conducted and the result is compared with the case of nonuniform flow. It is concluded that the flow shear characteristic has significantly changed the cylinder vibration behavior.

Ge, Fei; Lu, Wei; Wang, Lei; Hong, You-Shi

2011-06-01

360

Effects of Amplitude and Frequency of Mechanical Vibration Stimulation on Cultured Osteoblasts  

NASA Astrophysics Data System (ADS)

Mechanical stimulation to bones affects bone formation such as decrease of bone mass of astronauts under zero gravity, walking rehabilitation to bone fracture and fracture repair with ultrasound devices. Bone cells have been reported to sense and response to mechanical stimulation at cellular level morphologically and metabolically. In the view of mechanical vibrations, bone cells are deformed according to mechanical stimulation and their mechanical characteristics. In this study, sinusoidal inertia force was applied to cultured osteoblasts, which are a kind of bone cells, and effects of frequency and acceleration amplitude of mechanical vibration on the cells were investigated in respect of the cell proliferation, bone matrix generation and alkaline phosphatase (ALP) gene expression. The results to be obtained are as follows. The significant difference of cell density and bone mass generation between the non-vibrating and vibrating groups is found. ALP gene expression shows a peak to frequency at 50 Hz and the value of it is approximately 4.5 times as high as that of the non-vibrating group in the case of the acceleration amplitude of 0.5 G. ALP gene expression at 0.5 G is significantly larger than at 0, 0.125 or 0.25 G in the case of the frequency of 50 Hz.

Shikata, Tetsuo; Shiraishi, Toshihiko; Morishita, Shin; Takeuchi, Ryohei; Saito, Tomoyuki

361

Expansion characteristics of a nutritious extruded snack food using response surface methodology  

Microsoft Academic Search

Response surface methodology was used to analyze the effect of screw speed (220–340 rpm), feed moisture (11.0–15.0%, wet basis) and feed rate (22.0–26.0 kg\\/h, wet basis) on the physical properties (i.e., bulk density, expansion, porosity) of a nutritionally balanced extruded snack food. Regression equations describing the effect of each variable on the responses were obtained. Responses were most affected by changes in

EmirAy?e ?zer; ?enol ?bano?lu; Paul Ainsworth; Cahide Ya?mur

2004-01-01

362

Photosynthetic characteristics of coffee (Coffea arabusta) plantlets in vitro in response to different CO 2 concentrations and light intensities  

Microsoft Academic Search

The photosynthetic characteristics of coffee ( Coffea arabusta) plantlets cultured in vitro in response to different CO2 concentrations inside the culture vessel and photosynthetic photon flux (PPF) were investigated preliminarily. The estimation\\u000a of net photosynthetic rate (Pn) of coffee plantlets involved three methods: (1) estimating time courses of actual Pn in situ based on measuring CO2 concentrations inside and outside

Quynh Thi Nguyen; Toyoki Kozai; Genhua Niu; Uyen Van Nguyen

1998-01-01

363

NSLS II Vibration and Acoustic Criteria Vibration Experiment Hall  

E-print Network

Incorporated as part of the APS design effort, reported in "Measurement of Noise and Vibration: NationalNSLS II Vibration and Acoustic Criteria Vibration ­ Experiment Hall The vibration limits at this time. It may only be possible to represent the vibration requirements of this space using generic

Ohta, Shigemi

364

Parent and Child MMPI Responses: Characteristics among Families with Adolescents in Inpatient and Outpatient Setting.  

ERIC Educational Resources Information Center

The relationship of parent personality to child psychopathology has been investigated in numerous studies over the past three decades, using the Minnesota Multiphasic Personality Inventory (MMPI). To investigate response patterns of both parents and offspring, the MMPI responses of 197 families with adolescents entering inpatient or outpatient…

Archer, Robert P.; And Others

365

Response and characteristics of structures subjected to S-H waves  

NASA Technical Reports Server (NTRS)

A study of the dynamic characteristics of a coupled translational-rotational system is given. The formulation of the problem considers the soil-structure interaction effects by utilizing the impedance functions at the foundation of a structure. Due to the fact that the coefficient matrix in the characteristic equation is frequency dependent in nature, iterations have to be performed to find the nature frequencies of the system. Examples and discussions are presented. Comparisons of the analytical results from various approaches are also given.

Wu, S. T.

1984-01-01

366

Vibrating fuel grapple  

DOEpatents

A reactor refueling method utilizing a vibrating fuel grapple for removing spent fuel assemblies from a reactor core which incorporates a pneumatic vibrator in the grapple head, enabling additional withdrawal capability without exceeding the allowable axial force limit. The only moving part in the vibrator is a steel ball, pneumatically driven by a gas, such as argon, around a track, with centrifugal force created by the ball being transmitted through the grapple to the assembly handling socket.

Chertock, deceased, Alan J. (late of San Francisco, CA); Fox, Jack N. (San Jose, CA); Weissinger, Robert B. (Santa Clara, CA)

1982-01-01

367

THE APPLICATION OF ULTRASONIC VIBRATION DRILLS IN TRAUMATOLOGY  

Microsoft Academic Search

The dynamics of ultrasonic vibration drills having the common source of rotational and reciprocal movement of the driven element has been examined. The method, the mathematical model and the specific soft- ware for the calculation of the dynamic characteristics of the drills have been developed, with regard to the power limitation of the source, namely the rod ultrasonic vibrating system.

S. E. Kvashnin; E. V. Bosova

2003-01-01

368

Vibration monitoring of high speed spindles using spectral analysis techniques  

Microsoft Academic Search

A significant source of noise and vibration in precision high speed machine tool spindles is bearing induced vibration, which is caused by inherent geometrical characteristics, as well as out-of-balance assembly and interactions between rolling mating members with surface irregularities. The multitude of causes often makes a diagnostic approach quite arduous, particularly due to insufficient information obtained from frequency domain analysis

S. Vafaei; H. Rahnejat; R. Aini

2002-01-01

369

Liquid adhesion to an ultrasonically vibrating end surface  

Microsoft Academic Search

There exists a unique phenomenon of a large amount of liquid adhering to an ultrasonically vibrating end surface in the horizontal plane. The droplet assumes characteristic shapes that depend on the amplitude of vibration. In order to examine the mechanism of this phenomenon, the effects of the intrinsic surface tension of the adhering liquid and distribution of the intensity of

S. Tamura; Y. Tsunekawa; M. Okumiya; Y. Furukawa

2005-01-01

370

Cancer breakthrough pain characteristics and responses to treatment at a VA medical center  

Microsoft Academic Search

The purpose of this study is to analyze cancer breakthrough pain (BP) characteristics and how BP responds to conventional cancer pain management. Seventy-four cancer pain patients with worst pain severity ?4 out of 10 completed the Brief Pain Inventory (BPI), Memorial Symptom Assessment Scale-Short Form, Functional Assessment Cancer Therapy and Breakthrough Pain Questionnaires (BPQ) at an initial interview. Agency for

Shirley S Hwang; Victor T Chang; Basil Kasimis

2003-01-01

371

"It's a Snake, You Guys!": The Power of Text Characteristics on Children's Responses to Information Books.  

ERIC Educational Resources Information Center

Describes ways in which a small group of preschool children in an urban Head Start Program responded to typical information books during read-aloud sessions. Notes results of a group pretend reading of books children had just heard. Concludes even young children are attuned to characteristics of texts. (PM)

Tower, Cathy

2002-01-01

372

Characteristics of Permafrost Forests in Siberia and Potential Responses to Warming Climate  

Microsoft Academic Search

\\u000a The purpose of this chapter is to synthesize what have been reported in the preceding chapters, and to discuss (1) major characteristics\\u000a in the structure, function, and development patterns of the larch forests that grow on permafrost, and (2) how their structure\\u000a and function may change due to the warming climate.

A. Osawa; Y. Matsuura; T. Kajimoto

373

Product Line Characteristics as Determinants of Quick Response Implementation for U.S. Apparel Manufacturers  

Microsoft Academic Search

The purpose of this study was to identify the implementation of QR technologies by a broad spectrum of U.S. apparel manufacturers and to examine relationships between organizational characteristics and implementation of QR technologies. Conceptual framework for the study was based on the environmental interpretation model in the business domain (Daft & Weick, 1984, p. 284). The implementation level of selected

Eunju Ko; Doris H. Kincade

1998-01-01

374

Cognitive and Psychosocial Characteristics of Gifted Students with Written Language Disability: A Reply to Lovett's Response  

ERIC Educational Resources Information Center

Our article describing the characteristics of gifted students with a specific learning disability (SLD) in written language was criticized for emphasizing an ability achievement discrepancy as an indication of a written language disability and for not ruling out alternative explanations for the observed difficulties. The three primary alternative…

Assouline, Susan G.; Nicpon, Megan Foley; Whiteman, Claire S.

2011-01-01

375

Multistimuli-responsive azobenzene nanofibers with aggregation-induced emission enhancement characteristics.  

PubMed

A new azobenzene-based chromophore was synthesized to create one-dimensional (1D) nanofibers with aggregation-induced emission enhancement characteristics. The enhanced red fluorescence of the fibrous structures can be switched off via mechanical pressure, friction, or heat by pressing, rubbing, or annealing. PMID:25375197

Han, Mina; Cho, Sung June; Norikane, Yasuo; Shimizu, Masaki; Kimura, Akinori; Tamagawa, Tomokazu; Seki, Takahiro

2014-12-25

376

Quantifying the role of climate and landscape characteristics on hydrologic partitioning and vegetation response  

E-print Network

and density, plant biochemistry and physiology, nutrient availability, soil and landscape structureQuantifying the role of climate and landscape characteristics on hydrologic partitioning wetting vaporized by plants, known as the Horton index, is strongly related to the ratio of available

Troch, Peter

377

Familial Transmission of Continuous Performance Test Behavior: Attentional and Impulsive Response Characteristics  

Microsoft Academic Search

Continuous Performance Tests (CPTs) provide information on attentional processing and impulsive behavior. The results of previous research that used self-report measures have provided evidence for familial transmission (through genetic and\\/or environmental influences) of impulsive characteristics. The authors of the present study examined whether the impulsive behavioral parameters that are measured by the CPT also share familial relationships. The researchers asked

Donald M. Dougherty; James M. Bjork; F. GERARD Moeller; R. ANDREW Harper; Dawn M. Marsh; Charles W. Mathias; Alan C. Swann

2003-01-01

378

Corporate Responsiveness to Community Stakeholders: Effects of Contextual and Organizational Characteristics  

E-print Network

, and mergers and acquisitions) factors on the two measures of corporate community responsiveness. The authors ownership or mergers and acquisitions. The implications of these results for the instrumental aspect

Lin, Xiaodong

379

LANDSAT 3 return beam vidicon response artifacts: A report on RBV photographic product characteristics and quality coding system  

NASA Technical Reports Server (NTRS)

Analysis of large volumes of LANDSAT 3 RBV digital data that were converted to photographic form led to the firm identification of several visible artifacts (objects or structures not normally present, but producted by an external agency or action) in the imagery. These artifacts were identified, categorized, and traced directly to specific sensor response characteristics. None of these artifacts is easily removed and all cases remain under active study of possible future enhancement. The seven generic categories of sensor response artifacts identified to date include: (1) shading and stairsteps; (2) corners out of focus; (3) missing reseaus; (4) reseau distortion and data distortion; (5) black vertical line; (6) grain effect; and (7) faceplate contamination. An additional category under study, but not yet determined to be caused by sensor response, is a geometric anomaly. Examples of affected imagery are presented to assist in distinguishing between image content and innate defects caused by the sensor system.

Clark, B. P.

1981-01-01

380

Frequency response characteristics of isolated retinas from hatchling leatherback (Dermochelys coriacea L.) and loggerhead (Caretta caretta L.) sea turtles.  

PubMed

Electroretinographic recordings were made from hatchling loggerhead and leatherback sea turtle eyecup preparations during presentation of sinusoidally modulated lights of different frequencies, mean intensities and colors. Cross-correlation analysis was performed to determine the extent to which the responses followed the intensity modulated light sources. For both species mean light intensity had no significant effect on the frequency modulated responses over a 1.5 log unit range of intensities. Both species showed the best following to blue light and the poorest tracking to red light. Leatherback retinas did not follow frequencies above 10 Hz, while loggerhead responses extended out to 15 Hz. These visual low pass filter characteristics are consistent with attributes of the visual ecology of each species, as well as with the latencies and slow rise times exhibited by these retinas to brief flashes of light. PMID:19146881

Horch, Kenneth; Salmon, Michael

2009-04-15

381

Experimental determination of material damping using vibration analyzer  

NASA Technical Reports Server (NTRS)

Structural damping is an important dynamic characteristic of engineering materials that helps to damp vibrations by reducing their amplitudes. In this investigation, an experimental method is illustrated to determine the damping characteristics of engineering materials using a dual channel Fast Fourier Transform (FFT) analyzer. A portable Compaq III computer which houses the analyzer, is used to collect the dynamic responses of three metal rods. Time-domain information is analyzed to obtain the logarithmic decrement of their damping. The damping coefficients are then compared to determine the variation of damping from material to material. The variations of damping from one point to another of the same material, due to a fixed point excitation, and the variable damping at a fixed point due to excitation at different points, are also demonstrated.

Chowdhury, Mostafiz R.; Chowdhury, Farida

1990-01-01

382

Thermal Vibrational Convection in a Two-phase Stratified Liquid  

NASA Technical Reports Server (NTRS)

The response of a two-phase stratified liquid system subject to a vibration parallel to an imposed temperature gradient is analyzed using a hybrid thermal lattice Boltzmann method (HTLB). The vibrations considered correspond to sinusoidal translations of a rigid cavity at a fixed frequency. The layers are thermally and mechanically coupled. Interaction between gravity-induced and vibration-induced thermal convection is studied. The ability of applied vibration to enhance the flow, heat transfer and interface distortion is investigated. For the range of conditions investigated, the results reveal that the effect of vibrational Rayleigh number and vibrational frequency on a two-phase stratified fluid system is much different than that for a single-phase fluid system. Comparisons of the response of a two-phase stratified fluid system with a single-phase fluid system are discussed.

Chang, Qingming; Alexander, J. Iwan D.

2007-01-01

383

The development of interior noise and vibration criteria  

NASA Technical Reports Server (NTRS)

A generalized model was developed for estimating passenger discomfort response to combined noise and vibration. This model accounts for broadband noise and vibration spectra and multiple axes of vibration as well as the interactive effects of combined noise and vibration. The model has the unique capability of transforming individual components of noise/vibration environment into subjective comfort units and then combining these comfort units to produce a total index of passenger discomfort and useful sub-indices that typify passenger comfort within the environment. An overview of the model development is presented including the methodology employed, major elements of the model, model applications, and a brief description of a commercially available portable ride comfort meter based directly upon the model algorithms. Also discussed are potential criteria formats that account for the interactive effects of noise and vibration on human discomfort response.

Leatherwood, J. D.; Clevenson, S. A.; Stephens, D. G.

1990-01-01

384

Bone Response to Surface-Modified Titanium Implants: Studies on the Early Tissue Response to Implants with Different Surface Characteristics  

PubMed Central

In a series of experimental studies, the bone formation around systematically modified titanium implants is analyzed. In the present study, three different surface modifications were prepared and evaluated. Glow-discharge cleaning and oxidizing resulted in a highly stoichiometric TiO2 surface, while a glow-discharge treatment in nitrogen gas resulted in implants with essentially a surface of titanium nitride, covered with a very thin titanium oxide. Finally, hydrogen peroxide treatment of implants resulted in an almost stoichiometric TiO2, rich in hydroxyl groups on the surface. Machined commercially pure titanium implants served as controls. Scanning Auger Electron Spectroscopy, Scanning Electron Microscopy, and Atomic Force Microscopy revealed no significant differences in oxide thickness or surface roughness parameters, but differences in the surface chemical composition and apparent topography were observed. After surface preparation, the implants were inserted in cortical bone of rabbits and evaluated after 1, 3, and 6 weeks. Light microscopic evaluation of the tissue response showed that all implants were in contact with bone and had a large proportion of newly formed bone within the threads after 6 weeks. There were no morphological differences between the four groups. Our study shows that a high degree of bone contact and bone formation can be achieved with titanium implants of different surface composition and topography. PMID:24174936

Larsson Wexell, C.; Thomsen, P.; Aronsson, B.-O.; Tengvall, P.; Rodahl, M.; Lausmaa, J.; Kasemo, B.; Ericson, L. E.

2013-01-01

385

Vibration characteristics of mistuned shrouded blade assemblies  

NASA Technical Reports Server (NTRS)

An investigation of the mode localization phenomenon associated with mistuning is presented for shrouded blade assemblies. The calculations are based on a generic finite element model, which permits modeling of arbitrary mistuning and both slipping and nonslipping shroud interfaces. The results presented indicate that interactions occur between mistuning and slip effects, with maximum mode localization occurring when the shrouds slip freely. Certain modes are found to be very sensitive to shroud slip, and in some cases completely change character when slip occurs. Mode localization is most pronounced in the predominantly bending modes, and varies considerably from mode to mode. As the ratio of interblade coupling strength to mistuning strength is increased, the effect of mistuning is observed to decrease significantly. This result has important implications for the flutter problem, since it suggests that the stabilization effect available from mistuning is significantly less for a shrouded rotor as compared to an unshrouded rotor.

Bendiksen, O. O.; Valero, N. A.

1985-01-01

386

Vibrational analysis of rectangular sandwich plates resting on some elastic point supports  

SciTech Connect

An approximate solution of forced-vibration for rectangular sandwich plate resting on some elastic point supports is presented. The sandwich plate has thin, anisotropic composite laminated faces and a thick orthotropic core. The simplified sandwich plate model is used in the analysis. The governing equation of elastically point supported rectangular sandwich plate is obtained by using the Lagrange equation. The steady state response solution to a sinusoidally varying point force is also derived. The response curves of rectangular sandwich plates having CFRP laminated faces and aluminum honeycomb core is calculated. Application examples illustrate the effects of laminate lay-up of face sheets, core material properties and core thickness ratio on the vibration characteristics of rectangular sandwich plate.

Ichinomiya, Osamu; Maruyama, Koichi; Sekine, Kouji [Hokkaido Inst. of Tech., Sapporo (Japan). Dept. of Mechanical engineering

1995-11-01

387

Some buffet response characteristics of a twin-vertical-tail configuration  

NASA Technical Reports Server (NTRS)

A rigid, 1/6 size, full span model of an F-18 airplane was fitted with flexible vertical tails of two different levels of stiffness that were buffet tested in the Langley Transonic Dynamics Tunnel. Vertical tail buffet response results that were obtained over the range of angles of attack from -10 to 40 degs, and over the range of Mach numbers from 0.30 to 0.95 are presented. These results indicate the following: (1) the response occurs in the first bending mode; (2) the response increases with increasing dynamic pressure, but changes in response are not linearly proportional to the changes in dynamic pressure; (3) the response is larger at M = 0.30 than it is at the higher Mach numbers; (4) the maximum intensity of the buffeting is described as heavy to severe using an assessment criteria proposed by another investigator; and (5) the data at different dynamic pressures and for the different tails correlate reasonably well using the buffet excitation parameter derived from the dynamic analysis of buffeting.

Cole, Stanley R.; Moss, Steven W.; Doggett, Robert V., Jr.

1990-01-01

388

Growth characteristics and response to climate change of Larix Miller tree-ring in China  

Microsoft Academic Search

As one of the earliest species used in dendrochronological studies, Larix responds sensitively to climate change. In this study, nine larch species and one variety from eleven sites were collected\\u000a to study the growth characteristics of tree-ring width using dendrochronological methods. Ten residual tree-ring chronologies\\u000a were developed to analyze their relationships with regional standardized anomaly series by Pearson’s correlation analysis.

Yu Sun; LiLi Wang; Jin Chen; JianPing Duan; XueMei Shao; KeLong Chen

2010-01-01

389

Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts  

NASA Astrophysics Data System (ADS)

Dynamic collapses of deeply mined coal rocks are severe threats to miners; in order to predict collapses more accurately using electromagnetic radiation (EMR), we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials (gas, water and coal) and energy with its environment and gradually transitions from its original stable equilibrium structure to a nonequilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolution processes. Moreover, the dissipated energy caused by the damage evolutions, such as crack propagation, fractal sliding and shearing, can be regarded as the fingerprint of various EMR micro-mechanics. The dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures) and temporal (dynamic evolution) characteristics of coal rocks and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to understand the EMR mechanism in detail and to increase the accuracy of the EMR method in forecasting dynamic disasters.

Hu, S.; Wang, E.; Liu, X.

2014-08-01

390

Spatiotemporal multifractal characteristics of electromagnetic radiation in response to deep coal rock bursts  

NASA Astrophysics Data System (ADS)

Dynamic collapses of deeply mined coal rocks are severe threats to miners, in order to predict the collapses more accurately using electromagnetic radiation (EMR), we investigate the spatiotemporal multifractal characteristics and formation mechanism of EMR induced by underground coal mining. Coal rock in the burst-prone zone often exchanges materials and energy with its environment and gradually transits from its original stable equilibrium structure to a non-equilibrium dissipative structure with implicit spatiotemporal complexity or multifractal structures, resulting in temporal variation in multifractal EMR. The inherent law of EMR time series during damage evolution was analyzed by using time-varying multifractal theory. Results show that the time-varying multifractal characteristics of EMR are determined by damage evolutions process, the dissipated energy caused by damage evolutions such as crack propagation, fractal sliding and shearing can be regarded as the fingerprint of various EMR micro-mechanics. Dynamic spatiotemporal multifractal spectrum of EMR considers both spatial (multiple fractures) and temporal (dynamic evolution) characteristics of coal rocks, and records the dynamic evolution processes of rock bursts. Thus, it can be used to evaluate the coal deformation and fracture process. The study is of significance for us to in-depth understand EMR mechanism and to increase the accuracy of applying the EMR method to forecast dynamic disasters.

Shaobin, H.; Enyuan, W.; Xiaofei, L.

2014-04-01

391

Innate immune response to oral bacteria and the immune evasive characteristics of periodontal pathogens  

PubMed Central

Periodontitis is a chronic inflammation of periodontal tissue caused by subgingival plaque-associated bacteria. Periodontitis has long been understood to be the result of an excessive host response to plaque bacteria. In addition, periodontal pathogens have been regarded as the causative agents that induce a hyperinflammatory response from the host. In this brief review, host-microbe interaction of nonperiodontopathic versus periodontopathic bacteria with innate immune components encountered in the gingival sulcus will be described. In particular, we will describe the susceptibility of these microbes to antimicrobial peptides (AMPs) and phagocytosis by neutrophils, the induction of tissue-destructive mediators from neutrophils, the induction of AMPs and interleukin (IL)-8 from gingival epithelial cells, and the pattern recognition receptors that mediate the regulation of AMPs and IL-8 in gingival epithelial cells. This review indicates that true periodontal pathogens are poor activators/suppressors of a host immune response, and they evade host defense mechanisms. PMID:23507986

Ji, Suk

2013-01-01

392

Assessment of Waveguide Vibration Isolator.  

National Technical Information Service (NTIS)

A method is proposed for comparing the dynamic performance of different types of vibration isolators, and relies on having equal compression ratios of the rubber elements. The method is used to compare a waveguide vibration isolator with a blank vibration...

J. D. Dickens

1999-01-01

393

Vibration analysis of a split path gearbox  

NASA Astrophysics Data System (ADS)

Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.

Krantz, Timothy L.; Rashidi, Majid

1995-05-01

394

Vibration Analysis of a Split Path Gearbox  

NASA Technical Reports Server (NTRS)

Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.

Krantz, Timothy L.; Rashidi, Majid

1995-01-01

395

Vibration analysis of a split path gearbox  

NASA Technical Reports Server (NTRS)

Split path gearboxes can be attractive alternatives to the common planetary designs for rotorcraft, but because they have seen little use, they are relatively high risk designs. To help reduce the risk of fielding a rotorcraft with a split path gearbox, the vibration and dynamic characteristics of such a gearbox were studied. A mathematical model was developed by using the Lagrangian method, and it was applied to study the effect of three design variables on the natural frequencies and vibration energy of the gearbox. The first design variable, shaft angle, had little influence on the natural frequencies. The second variable, mesh phasing, had a strong effect on the levels of vibration energy, with phase angles of 0 deg and 180 deg producing low vibration levels. The third design variable, the stiffness of the shafts connecting the spur gears to the helical pinions, strongly influenced the natural frequencies of some of the vibration modes, including two of the dominant modes. We found that, to achieve the lowest level of vibration energy, the natural frequencies of these two dominant modes should be less than those of the main excitation sources.

Krantz, Timothy L.; Rashidi, Majid

1995-01-01

396

System and method of active vibration control for an electro-mechanically cooled device  

DOEpatents

A system and method of active vibration control of an electro-mechanically cooled device is disclosed. A cryogenic cooling system is located within an environment. The cooling system is characterized by a vibration transfer function, which requires vibration transfer function coefficients. A vibration controller generates the vibration transfer function coefficients in response to various triggering events. The environments may differ by mounting apparatus, by proximity to vibration generating devices, or by temperature. The triggering event may be powering on the cooling system, reaching an operating temperature, or a reset action. A counterbalance responds to a drive signal generated by the vibration controller, based on the vibration signal and the vibration transfer function, which adjusts vibrations. The method first places a cryogenic cooling system within a first environment and then generates a first set of vibration transfer function coefficients, for a vibration transfer function of the cooling system. Next, the cryogenic cooling system is placed within a second environment and a second set of vibration transfer function coefficients are generated. Then, a counterbalance is driven, based on the vibration transfer function, to reduce vibrations received by a vibration sensitive element.

Lavietes, Anthony D. (Hayward, CA); Mauger, Joseph (Livermore, CA); Anderson, Eric H. (Mountain View, CA)

2000-01-01

397

Vibration and noise  

NASA Astrophysics Data System (ADS)

A distinction is made between noise and pseudo-noise, noting the work of James Lighthill, and the different types of vibrations they excite are described. Consideration is given to noise produced by vortices and techniques for noise and vibration measurement are discussed.

Legendre, R.

1981-06-01

398

IPMCs as Vibration Sensors  

Microsoft Academic Search

Vibration sensing and control in structures and machinery are essential to prevent damage or failure. This paper proposes a new sensor, based on polymeric materials, to be used as a vibration sensor. Ionic polymer metal composites (IPMCs), active materials showing a bidirectional electromechanical coupling, are used. A new model has been developed and a test setup was realized using an

Brunetto Paola; Luigi Fortuna; Pietro Giannone; Salvatore Graziani; Salvatore Strazzeri

2008-01-01

399

Multiple direction vibration fixture  

DOEpatents

An apparatus for simulating a rocket launch environment on a test item undergoing centrifuge testing by subjecting the item simultaneously or separately to vibration along an axis of centripetal force and along an axis perpendicular to the centripetal force axis. The apparatus includes a shaker motor supported by centrifuge arms and a right angle fixture pivotally connected to one of the shaker motor mounts. When the shaker motor vibrates along the centripetal force axis, the vibrations are imparted to a first side of the right angle fixture. The vibrations are transmitted 90 degrees around the pivot and are directed to a second side of the right angle fixture which imparts vibrations perpendicular to the centripetal force axis. The test item is in contact with a third side of the right angle fixture and receives both centripetal-force-axis vibrations and perpendicular axis vibrations simultaneously. A test item can be attached to the third side near the flexible coupling or near the air bag to obtain vibrations along the centripetal force axis or transverse to the centripetal force axis.

Cericola, Fred (Albuquerque, NM); Doggett, James W. (Albuquerque, NM); Ernest, Terry L. (Albuquerque, NM); Priddy, Tommy G. (Rockville, MD)

1991-01-01

400

A nondeterministic shock and vibration application using polynomial chaos expansions  

SciTech Connect

In the current study, the generality of the key underpinnings of the Stochastic Finite Element (SFEM) method is exploited in a nonlinear shock and vibration application where parametric uncertainty enters through random variables with probabilistic descriptions assumed to be known. The system output is represented as a vector containing Shock Response Spectrum (SRS) data at a predetermined number of frequency points. In contrast to many reliability-based methods, the goal of the current approach is to provide a means to address more general (vector) output entities, to provide this output as a random process, and to assess characteristics of the response which allow one to avoid issues of statistical dependence among its vector components.

FIELD JR.,RICHARD V.; RED-HORSE,JOHN R.; PAEZ,THOMAS L.

2000-03-28

401

Effects of grouping and response characteristics of instructional objectives when learning from prose  

Microsoft Academic Search

Conducted a study with 375 high school students. The effects of requiring an overt or covert response to objectives when grouped before or interspersed throughout a text were investigated for intentional and incidental learning. In addition, 2 densities of specific and general objectives were investigated. Groups of about 30 Ss each were tested by their homeroom teachers. Results show greater

R. Kaplan

1976-01-01

402

CHARACTERISTICS OF ROAD TRAFFIC NOISE IN HANOI AND COMMUNITY RESPONSE TO NOISE  

Microsoft Academic Search

Though a number of social surveys on community responses to environmental noises have so far been conducted and accumulated in Euro-American countries, few social surveys have been conducted in Asian countries except Japan. No systematic data collected in Vietnam has been presented at the international stage. Vietnam is now in rapid economic growth and has serious environmental problems such as

P. T. H. Anh; P. T. H. Yen; T. D. Cuong; P. N. Dang; L. V. Nai; T. Nishimura; T. Sato; Y. Hashimoto; T. Yano

403

Characteristics of Maternal Verbal Style: Responsiveness and Directiveness in Two Natural Contexts  

ERIC Educational Resources Information Center

Twenty mothers' provision of responsive, supportive behavioural directive, and intrusive behavioural and attentional directive speech was investigated during interactions with their children at ages 0 ; 10, 1 ; 1, 1 ; 5 and 1 ; 9 in two natural contexts, free play and bathtime. Issues examined included developmental change, contextual differences,…

Flynn, Valerie; Masur, Elise Frank

2007-01-01

404

Plant Growth in Controlled Environments in Response to Characteristics of Nutrient Solutions  

NASA Technical Reports Server (NTRS)

Emphasis was given to environmental factors that alter the flux of carbohydrate from the shoot to the root system to support the absorption of nitrogen and the subsequent interaction between nitrogen uptake and whole plant growth. Only the nitrate form of nitrogen was utilized in order to establish base line responses for evaluation of future studies utilizing both ammonium and nitrate.

Raper, C. D., Jr.

1982-01-01

405

Acute administration of methylphenidate alters the prefrontal cortex neuronal activity in a dose-response characteristic  

PubMed Central

The prefrontal cortex (PFC) is part of the collective structures known as the motive circuit. The PFC acts to enhance higher cognitive functions as well as mediate the effects of psychostimulants. Previous literature shows the importance of PFC neuronal adaptation in response to acute and chronic psychostimulant exposure. The PFC receives input from other motive circuit structures, including the ventral tegmental area, which mediates and facilitates the rewarding effects of psychostimulant exposure. PFC neuronal and locomotor activity from freely behaving rats previously implanted with permanent semimicroelectrodes were recorded concomitantly using a telemetric (wireless) recording system. Methylphenidate (MPD) is used as a leading treatment for behavioral disorders and more recently as a cognitive enhancer. Therefore, the property of MPD dose response on PFC neuronal activity was investigated. The results indicate that MPD modulates PFC neuronal activity and behavioral activity in a dose-dependent manner. PFC neuronal responses to 0.6 mg/kg elicited mainly a decrease in PFC neuronal activity, while higher MPD doses (2.5 and 10.0 mg/kg) elicited mainly increased neuronal activity in response to MPD. The correlation between MPD effects on PFC neuronal activity and animal behavior is discussed. PMID:24883018

Claussen, Catherine M; Dafny, Nachum

2014-01-01

406

Z .Physica C 307 1998 318326 Characteristic low-field magnetic response of granular  

E-print Network

is numerically studied as a function of the inclination of the externally applied magnetic field H with respect of these systems makes it difficult to interpret their low-field magnetic response 4 . As far as the intergranular w xtreated elsewhere 9 . In the present paper we numerically evaluate the lower threshold field

Di Matteo, Tiziana

407

Processing load during listening: The influence of task characteristics on the pupil response  

Microsoft Academic Search

This study examined the magnitude of the pupillary response evoked by a number of tasks varying in the nature and complexity of the auditory and linguistic information provided. The tasks comprised passive listening, anticipation to verbally responding to a prompt signal, auditory detection, and the identification of meaningful words. Performance in the auditory detection and identification tasks was matched at

Sophia E. Kramer; Artur Lorens; Frans Coninx; Adriana A. Zekveld; Anna Piotrowska; Henryk Skarzynski

2012-01-01

408

Light response characteristics of net CO 2 exchange in brackish wetland plant communities  

Microsoft Academic Search

Photosynthetic responses to incident photon flux density (400–700 nm; PPFD) was studied in a grass community consisting of Spartina patens and Distichlis spicata and a mixed community having the two grasses and a sedge, Scirpus Olneyi. Net community CO2 exchange and incident PPFD were monitored from dawn to dusk in a large open gas exchange system, and a hyperbolic light

Bert G. Drake

1984-01-01

409

Counterattack or DelayCharacteristics Influencing Decision Makers' Responses To the Simulation of an Unidentified Attack  

Microsoft Academic Search

This paper reports a secondary analysis of a series of simulation runs which explored the effects of a broad array of variables on a nation's response to an imminent strategic attack from an unidentified source. Seven variables appeared as important in determining whether a nation would counterattack or delay retaliation when given such a warning. These variables include availability of

Charles F. Hermann; Margaret G. Hermann; Robert A. Cantor

1974-01-01

410

Using torsional vibration analysis as a synergistic method for crack detection in rotating equipment  

Microsoft Academic Search

A non-intrusive torsional vibration method for monitoring and tracking small changes in crack growth of reactor coolant pump shafts is presented in this paper. This method resolves and tracks characteristic changes in the natural torsional vibration frequencies that are associated with shaft crack propagation. The focus of this effort is to develop and apply the torsional vibration shaft cracking monitoring

Mitchell S. Lebold; K. Maynard; K. Reichard; M. Trethewey; D. Bieryla; Clifford Lissenden; David Dobbins

2004-01-01

411

Research of Active Vibration Control Algorithm Based on Online Control Channel Identification  

Microsoft Academic Search

As the accuracy of the control channel model directly affects the stability and the convergence of the active vibration controller for smart flexible structures, offline identification of the control channel model is inappropriate for a vibration system whose characteristic and parameter is time- varying. To solve the problem of the control channel model identification, an active vibration control algorithm based

Huang Quanzhen; Gao Zhiyuan; Gao Shouwei; Shao Yong; Zhu Xiaojin

2011-01-01

412

Elastomer materials in ship vibration and noise protection means  

Microsoft Academic Search

The use of different synthetic rubbers in ship vibration and noise protection means is reviewed. Comparison of mechanical,\\u000a acoustic, resource, and service life characteristics of these materials is presented.

A. V. Ionov; L. E. Buvailo; M. V. Volkova; A. P. Starostin

2010-01-01

413

Transient response of the rotor-support system of aeroengines  

Microsoft Academic Search

This paper develops a transfer matrix-direct integration method. In this research the support reactions, squeeze-film forces, and unbalance forces are separated into different vectors. Therefore, it is easy to analyze the response from unbalance of any disk or some disks by the governing equations derived for a definite characteristic disk. It can be used to analyze the vibrations matching of

Jialiu Gu; Xingmin Ren

1991-01-01

414

Measure the Crack Instead of Construction Vibrations by Charles H. Dowding, Ph.D., P.E.  

E-print Network

Measure the Crack Instead of Construction Vibrations by Charles H. Dowding, Ph.D., P.E. Figure 1 to address fears of vibration-induced cracking by directly measuring crack response. Relatively inexpensive. HOUSE AND CRACK RESPONSE TO VIBRATIONS Crack measurement concepts are illustrated by the response

415

Metabolic and physiological characteristics of immediate response to overheating in man  

Microsoft Academic Search

Intensified catabolism with activated proteolysis caused by stress and high temperature as a physical and chemical factor\\u000a was found to be the typical response of the human body at the first stage of acute overheating. The data on the glutathione,\\u000a which detoxifies lipid peroxides and protects proteins from oxidation, showed that hyperthermia strained the body antioxidant\\u000a mechanisms. The body resistance

L. I. Andreeva; V. V. Goranchuk; N. A. Stolyarova; L. I. Ivanova; M. V. Titova; V. S. Petrova; A. A. Boikova; T. M. Bogacheva; A. I. Rumyantseva

1999-01-01

416

Characteristic Immune Response in Peyer’s Patch Cells Induced by Oral Administration of Bifidobacterium Components  

Microsoft Academic Search

We demonstrate immunomodulatory effects, especially those involving murine intestinal IgA secretion, in Peyer's patch cells\\u000a following oral administration of Bifidobacterium immunomodulator (BIM) derived from sonicated B. pseudocatenulatum 7041. BALB\\/c mice were administered BIM orally for 7 consecutive days. The PP cells demonstrated upregulated secretion of\\u000a total IgA including BIM-specific IgA following BIM administration. In observing the response of PP cells

Yusuke Nakanishi; Akira Hosono; Yasuhiro Hiramatsu; Teiji Kimura; Ryo Nakamura; Shuichi Kaminogawa

2005-01-01

417

Root aerobic respiration and growth characteristics of three Typha species in response to hypoxia  

Microsoft Academic Search

The responses of root aerobic respiration to hypoxia in three common Typha species were examined. Typha latifolia L., T. orientalis Presl, and T. angustifolia L. were hydroponically cultivated under both aerobic and hypoxic growth conditions to measure root oxygen consumption rates.\\u000a Hypoxia significantly enhanced the root aerobic respiration capacity of the two deep-water species, T. orientalis and T. angustifolia, while

Tomomi Matsui; Takayoshi Tsuchiya

2006-01-01

418

Characteristics of Haemophilus influenzae Type b Responsible for Meningitis in Poland from 1997 to 2004  

Microsoft Academic Search

Two hundred forty-five H. influenzae isolates responsible for meningitis in Poland from 1997 to 2004 were studied. Among these, 233 (95.1%) belonged to serotype b (Hib), 2 belonged to serotype f, and 10 were noncapsulated. The relatedness of all isolates was evaluated by pulsed-field gel electrophoresis (PFGE), and selected representatives were evaluated by multilocus sequence typing. Resistance to ampicillin was

Anna Skoczynska; Marcin Kadøubowski; Joanna Empel; Waleria Hryniewicz

419

Characteristics of Haemophilus influenzae Type b Responsible for Meningitis in Poland from 1997 to 2004  

Microsoft Academic Search

Two hundred forty-five H. influenzae isolates responsible for meningitis in Poland from 1997 to 2004 were studied. Among these, 233 (95.1%) belonged to serotype b (Hib), 2 belonged to serotype f, and 10 were noncapsulated. The relatedness of all isolates was evaluated by pulsed-field gel electrophoresis (PFGE), and selected representatives were evaluated by multilocus sequence typing. Resistance to ampicillin was

Anna Skoczynska; M. Kadlubowski; Joanna Empel; Waleria Hryniewicz

2005-01-01

420

Modified ventilatory response characteristics to exercise in breath-hold divers.  

PubMed

Specific adjustments to repeated extreme apnea are not fully known and understood. While a blunted ventilatory chemosensitivity to CO2 is described for elite breath-hold divers (BHDs) at rest, it is unclear whether specific adaptations affect their response to dynamic exercise. Eight elite BHDs with a previously validated decrease in CO2 chemosensitivity, 8 scuba divers (SCDs), and 8 matched control subjects were included in a study where markers of ventilatory response, Fowler's dead space, partial pressure of carbon dioxide (pCO2), and blood lactate concentrations during cycle exercise were measured. Maximal power output did not differ between the groups, but lactate threshold (?L) appeared at a significantly lowered respiratory compensation point (RCP) and at a higher VO2 for the BHDs. End-tidal (petCO2) and estimated arterial pCO2 (paCO2) were significantly higher in BHDs at ?L, the RCP, and maximum exhaustion. BHDs showed a significantly (P < .01) slower breathing pattern in relation to a given tidal volume at a specific work rate. In summary, BHDs presented signs of a metabolic shift from aerobic to anaerobic energy supply, decreased chemosensitivity during exercise, and a distinct ventilatory-response pattern during cycle exercise that differs from SCDs and controls. PMID:24231513

Roecker, Kai; Metzger, Jule; Scholz, Tobias; Tetzlaff, Kay; Sorichter, Stephan; Walterspacher, Stephan

2014-09-01