Sample records for vibration response characteristics

  1. Vibration Characteristics of Thermoplastic Composite

    NASA Astrophysics Data System (ADS)

    Haldar, Amit Kumar; Singh, Satnam; Prince

    2011-12-01

    Unreinforced, Long fiber and Short fiber polypropylene composites are being used in many antivibration applications, due to their time and temperature dependent specific mechanical properties. Their good damping behavior accounts for many engineering applications. For utilization of these materials in specific engineering applications, there is a need to understand the damping behavior of composites under dynamic load. For this work, unreinforced and 20% long and short reinforced glass fiber polypropylene composite materials were tested for forced transverse vibration damping characteristics under static as well as fatigue loading conditions. The damping characteristics are quantified by forced frequency response of the test material. Presence of reinforced fibers increases the damping capacity. Among reinforcements, short fiber reinforced polypropylene shows increased damping capacity then long glass fiber reinforced.

  2. Modeling differences in the vibration response characteristics of the human body

    Microsoft Academic Search

    S. D Smith

    2000-01-01

    Mathematical models may provide a useful tool for the development and evaluation of seating systems for vibration mitigation. A five-degree-of-freedom (DOF) model was formulated based on the measured driving-point impedance and transmissibilities of major anatomical structures contributing to the observed resonance behaviors. The model was limited in its ability to simulate differences observed in the resonance behaviors of a broader

  3. Investigation of vibration characteristics of electric motors

    NASA Technical Reports Server (NTRS)

    Bakshis, A. K.; Tamoshyunas, Y. K.

    1973-01-01

    The vibration characteristics of electric motors were analyzed using mathematical statistics methods. The equipment used and the method of conducting the test are described. Curves are developed to show the visualization of the electric motor vibrations in the vertical direction. Additional curves are included to show the amplitude-phase frequency characteristic of dynamic rotor-housing vibrations at the first lug and the same data for the second lug of the electric motor. Mathematical models were created to show the transmission function of the dynamic rotor housing system.

  4. Vibration characteristic of high power CO2 laser

    NASA Astrophysics Data System (ADS)

    Zhang, Kuo

    2015-02-01

    High power CO2 laser is widely used in various scientific, industrial and military applications. Vibration is a common phenomenon during laser working process, it will affect the working performance of high power CO2 laser, vibration must be strictly controlled in the condition where the laser pointing is required. This paper proposed a method to investigate the vibration characteristic of high power CO2 laser. An experiment device with vibration acceleration sensor was established to measure vibration signal of CO2 laser, the measured vibration signal was mathematically treated using space-frequency conversion, and then the vibration characteristic of high power CO2 laser can be obtained.

  5. Vibration Modes and Characteristic Length Scales in Amorphous Materials

    NASA Astrophysics Data System (ADS)

    Tanguy, Anne

    2015-06-01

    The numerical study of the mechanical responses of amorphous materials at the nanometer scale shows characteristic length scales that are larger than the intrinsic length of the microstructure. In this article, we review the different scales appearing upon athermal elastoplastic mechanical load and we relate it to a detailed study of the vibrational response. We compare different materials with different microstructures and different bond directionality (from Lennard-Jones model materials to amorphous silicon and silicate glasses). This work suggests experimental measurements that could help to understand and, if possible, to predict plastic deformation in glasses.

  6. Physiology responses of Rhesus monkeys to vibration

    NASA Astrophysics Data System (ADS)

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

    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

  7. A study of characteristics of disk vibration and rotating airflow in magneto optical disk drives

    Microsoft Academic Search

    Sookyung Kim; Gyuhyeon Han; Heuigi Son

    1998-01-01

    A study on the dynamic characteristics of rotating disks in magneto optical disk drives is presented. The natural frequencies of the rotating disks are investigated experimentally and numerically. The frequency response and critical speeds of the advanced storage magneto optical (ASMO) disk are discussed. The characteristics of airflow around the disk and their effects on the disk vibrations are also

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

    PubMed

    Kim, Jae Ho; Jeon, Jin Yong

    2014-10-01

    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

  9. Scale-model characterization of flow-induced vibrational response of FFTF reactor internals

    SciTech Connect

    Ryan, J. A.; Mahoney, J. J.

    1980-10-01

    Fast Test Reactor core internal and peripheral components were assessed for flow-induced vibrational characteristics under scaled and simulated prototype flow conditions in the Hydraulic Core Mockup as an integral part of the Fast Test Reactor Vibration Program. The Hydraulic Core Mockup was an 0.285 geometric scale model of the Fast Test Reactor internals designed to simulate prototype vibrational and hydraulic characteristics. Using water to simulate sodium coolant, vibrational characteristics were measured and determined for selected model components over the scaled flow range of 36 to 110%. Additionally, in-situ shaker tests were conducted on selected Hydraulic Core Mockup outlet plenum components to establish modal characteristics. Most components exhibited resonant response at all test flow rates; however, the measured dynamic response was neither abnormal nor anomalously flow-rate dependent, and the predicted prototype components' response were deemed acceptable.

  10. Vibration characteristics of a steadily rotating slender ring

    NASA Technical Reports Server (NTRS)

    Lallman, F. J.

    1980-01-01

    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.

  11. Vibrational characteristic features and band intensities in solving two-dimensional inverse vibrational problems

    NASA Astrophysics Data System (ADS)

    Nikolova, B. M.

    1993-10-01

    An iterative approach to solving the inverse vibrational problem is used for two-dimensional molecular force field species and all their multiple solutions are obtained. Two methods, one of isotopic molecular force constant invariance and another of differential increments of the force constants, are applied to methane, silane, germane, stannane, ammonia, phosphine, arsine, stibine and their deuterium isotopes, as well as to tetrafluoromethane and its carbon-13 isotope, Criteria for physical significance of each solution based on the characteristic features of the normal vibrations are utilized in discriminating between the multiple solutions. The vibrational intensities are used in an attempt to determine the sign combination for the dipole moment derivatives with respect to the normal coordinates. The force constant results agree very well with those obtained by the parametric approach to the two-dimensional inverse vibrational problem solved for the same molecules [B.M. Nikolova, J. Mol. Struct., 291 (1993) 123].

  12. Coupled free vibration characteristics of rotating tuned bladed disk systems

    Microsoft Academic Search

    V. Omprakash; V. Ramamurti

    1990-01-01

    A detailed qualitative study is presented of the coupled free vibration characteristics of rotating turbomachinery bladed disk systems having useful ranges of geometric parameters. The analysis is carried out by using a three noded triangular shell element having six degrees of freedom per node together with the cyclic symmetric nature of the problem. The blade and disk attachment is established

  13. A direct evidence of vibrationally delocalized response at ice surface

    SciTech Connect

    Ishiyama, Tatsuya; Morita, Akihiro, E-mail: morita@m.tohoku.ac.jp [Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578 (Japan)

    2014-11-14

    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.

  14. A direct evidence of vibrationally delocalized response at ice surface

    NASA Astrophysics Data System (ADS)

    Ishiyama, Tatsuya; Morita, Akihiro

    2014-11-01

    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.

  15. A direct evidence of vibrationally delocalized response at ice surface.

    PubMed

    Ishiyama, Tatsuya; Morita, Akihiro

    2014-11-14

    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

  16. Vibrational characteristics of Balinese gamelan metallophones.

    PubMed

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

    2010-05-01

    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

  17. Vibration Exposure and Biodynamic Responses during Whole-Body Vibration Training

    Microsoft Academic Search

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

    2007-01-01

    ABERCROMBY, A. F. J., W. E. AMONETTE, C. S. LAYNE, B. K. MCFARLIN, M. R. HINMAN, and W. H. PALOSKI. Vibration Exposure and Biodynamic Responses during Whole-Body Vibration Training. Med. Sci. Sports Exerc., Vol. 39, No. 10, pp. 1794-1800, 2007. Purpose: Excessive, chronic whole-body vibration (WBV) has a number of negative side effects on the human body, including disorders of

  18. Study the vibration and dynamic response of the dipole girder system for CSNS/RCS

    E-print Network

    Liu Renhong; Wang Min; Zhang JunSong; Wang GuangYuan

    2015-06-24

    China Spallation Neutron Source is a high intensity proton accelerator based facility, and its accelerator complex includes two main parts an H- linac and a rapid cycling synchrotron. The RCS accumulates the 80MeV proton beam, and accelerates it to 1.6GeV, with a repetition rate of 25Hz. The dipole of the CSNS RCS is operated at a 25 Hz sinusoidal alternating current which causes severe vibrate. The vibration will influence the long term safety and reliable operation of the magnet. The dipole of the CSNS RCS is an active vibration equipment which is different from the ground vibration accelerator. It is very important to design and study the dynamic characteristics of the dipole girder system. This paper takes the dipole and girder as a specific model system, a method for studying the dynamic characteristics of the system is put forward by combining theoretical calculation with experimental testing. The modal parameters with and without vibration isolator of the dipole girder system are obtain through ANSYS simulation and testing. Then the dynamic response of the system is calculated with modal analysis and vibration testing data. The dipole girder takes four-point support system which maybe appears over constrained in the progress of adjustment. The dynamic characteristics and dynamic response of the three point girder system were studied with the same method.

  19. Vibration and formability characteristics of aluminum-polymer sandwich materials

    NASA Astrophysics Data System (ADS)

    Somayajulu, Thamma S. V.

    Metal/polymer/metal sandwich materials are finding increasing use in the automotive industry primarily as lightweight alternatives to steel and aluminum alloys. In addition to low density they also offer other functional benefits e.g. improved vibration damping. In order to exploit such beneficial characteristics it is necessary to examine the manufacturability of these materials. In this work the vibration characteristics and formability were examined in selected materials, chosen from a group of aluminum/polypropylene/aluminum sandwich materials. First, a systematic study was carried out on vibration characteristics of square sandwich plates using 3D finite element models and usefulness of such a 3D displacement field in understanding the damping mechanisms as well as their contributions toward the modal damping were discussed. Second, a study of stretch formability of several sandwich materials was conducted. Since the knowledge of tensile properties is essential for understanding the formability, those properties were determined by performing uniaxial tensile tests on several aluminum/polypropylene/aluminum (HyliteRTM) sandwich materials and their constituent materials. The phenomena of diffused necking and deformation of material up to and beyond the point of necking were systematically investigated. Furthermore, the formability of sandwich materials was assessed by comparing the experimentally determined forming limit diagrams (FLDs) of monolithic 5182 aluminum and several sandwich materials. In addition to the experimental research, theoretical modeling was carried out to predict formability based on the concept of growth of pre-existing defects. One such model, known as M-K analysis, was utilized on the basis of defects existing in (i) the aluminum skins and (ii) the overall thickness of the sandwich. The experimental and theoretical results suggest that the levels of forming limit in sandwich materials are far less than those for monolithic materials of equivalent stiffness. This result may be related to smaller defect factor in the skin of the sandwich materials.

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

    USGS Publications Warehouse

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

    1990-01-01

    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

  1. Sensitivity analysis of torsional vibration characteristics of helicopter rotor blades. Part 2: Aerodynamics and sensitivity analysis

    NASA Technical Reports Server (NTRS)

    Bratanow, T.; Ecer, A.

    1974-01-01

    A theoretical investigation of dynamic response characteristics of rotor blades was carried out with special emphasis on torsional degrees-of-freedom. Coupled equations of motion for flapwise bending and torsion were formulated at varying azimuth positions for rotor blades with noncollinear aerodynamic, elastic and mass axes. Both structural and aerodynamic mass, damping and stiffness coefficients were included. The variations of a sample blade at different flight conditions were investigated from these equations. The obtained numerical results were illustrated. The sensitivity of overall blade vibration characteristics to torsional oscillations was also investigated from the equations of motion for the sample blade. The illustrated results show the importance of torsional degrees-of-freedom in rotor blade analysis. Various possibilities of improving the overall response by tuning blade geometric, structural and aerodynamic characteristics are discussed.

  2. Transitional boundary-layer response to wall vibrations

    Microsoft Academic Search

    S. Y. Kim; X. Bonnardel; J. P. Guibergia; E. Brocher

    1994-01-01

    The effects of wall vibration on the development of Tollmien-Schlichting (T-S) waves in a transitional flat-plate boundary layer are considered. Theoretically, the dynamic interaction between T-S waves and velocity perturbations induced by the vibrating wall is demonstrated through the kinetic energy balance of velocity perturbations. For a compliant wall, the response of T-S waves to velocity perturbations induced by the

  3. Marine-riser vibration response determined by modal analysis

    Microsoft Academic Search

    D. W. Dareing; T. Huang

    1979-01-01

    Marine riser response calculations are usually based on finite element or finite difference methods. This paper outlines the modal analysis method as an alternate approach for calculating marine riser time-dependent stresses. An example problem shows that five natural vibration modes give acceptable convergence and engineering accuracy. Dynamic response calculations are, therefore, greatly simplified as only a limited number of eigenvalues

  4. Damage Identification of Piles Based on Vibration Characteristics

    PubMed Central

    Zhang, Xiaozhong; Yao, Wenjuan; Chen, Bo; Liu, Dewen

    2014-01-01

    A method of damage identification of piles was established by using vibration characteristics. The approach focused on the application of the element strain energy and sensitive modals. A damage identification equation of piles was deduced using the structural vibration equation. The equation contained three major factors: change rate of element modal strain energy, damage factor of pile, and sensitivity factor of modal damage. The sensitive modals of damage identification were selected by using sensitivity factor of modal damage firstly. Subsequently, the indexes for early-warning of pile damage were established by applying the change rate of strain energy. Then the technology of computational analysis of wavelet transform was used to damage identification for pile. The identification of small damage of pile was completely achieved, including the location of damage and the extent of damage. In the process of identifying the extent of damage of pile, the equation of damage identification was used in many times. Finally, a stadium project was used as an example to demonstrate the effectiveness of the proposed method of damage identification for piles. The correctness and practicability of the proposed method were verified by comparing the results of damage identification with that of low strain test. The research provided a new way for damage identification of piles. PMID:25506062

  5. Dynamic characteristics and modeling of a new magnetorheological damper for broadband vibration control

    NASA Astrophysics Data System (ADS)

    Tu, Fengchen; Chen, Zhaobo; Li, Hua; Jiao, Yinghou; Fang, Bo

    2007-07-01

    Magnetorheological (MR) dampers are smart devices characterized as high damping force, short response time and lower energy consumption. They provide a promising way for vehicle isolation. However, transmissibility of conventional MR damper increases significantly at high frequency because of stiffness hardening. For this reason, new MR damper with decoupling mechanism has been designed. The design is sensitive to amplitude and frequency of vibration, and produces stiffness and damping varied with amplitudes and frequencies vibrations. Dynamic model is derived based on Bingham model. Mathematical expressions of dynamic characteristics, including dynamic stiffness, delay angle, force transmission rate and dynamic range of damping force, are deducted by solving the models. Numerical simulations are used to study the dynamic characteristics. The results indicate that, the design produces large damping force in the low frequency high amplitude case and small damping force low stiffness in the opposite case. The high frequency stiffness hardening is avoided. This MR damper can be used to semi-active vibration control of vehicles.

  6. Analytical design and evaluation of an active control system for helicopter vibration reduction and gust response alleviation

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.; Zwicke, P. E.; Gold, P.; Miao, W.

    1980-01-01

    An analytical study was conducted to define the basic configuration of an active control system for helicopter vibration and gust response alleviation. The study culminated in a control system design which has two separate systems: narrow band loop for vibration reduction and wider band loop for gust response alleviation. The narrow band vibration loop utilizes the standard swashplate control configuration to input controller for the vibration loop is based on adaptive optimal control theory and is designed to adapt to any flight condition including maneuvers and transients. The prime characteristics of the vibration control system is its real time capability. The gust alleviation control system studied consists of optimal sampled data feedback gains together with an optimal one-step-ahead prediction. The prediction permits the estimation of the gust disturbance which can then be used to minimize the gust effects on the helicopter.

  7. Techniques for obtaining subjective response to vertical vibration

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    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.

  8. Rocket Launch-Induced Vibration and Ignition Overpressure Response

    NASA Technical Reports Server (NTRS)

    Caimi, Raoul; Margasahayam, Ravi; Nayfeh, Jamal; Thompson, Karen (Technical Monitor)

    2001-01-01

    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.

  9. Characteristics of spaceborne cooler passive vibration isolator by using a compressed shape memory alloy mesh washer

    NASA Astrophysics Data System (ADS)

    Oh, Hyun-Ung; Kwon, Seong-Cheol; Youn, Se-Hyun

    2015-01-01

    Cryogenic coolers produce undesirable micro-vibrations during on-orbit operation, which may seriously affect the image quality of high-resolution observation satellites. Micro-vibrations can be easily isolated by mounting the cooler on a vibration isolator with low stiffness to attenuate the vibration transmitted to the satellite structure. However, the structural safety of a cooler supported by an isolator with low stiffness cannot be guaranteed under the much more severe vibration condition of a launch environment. In this study, to guarantee vibration isolation performance in a launch environment while effectively isolating the micro-vibrations from the cooler on-orbit, a new type of passive vibration isolation system by using a compressed shape memory alloy mesh washer was proposed and investigated. The basic characteristics of the isolator were measured in static and free vibration tests of the isolator, and a simple equivalent model of the isolator was proposed. The effectiveness of the isolator design in a launch environment was demonstrated through sine vibration, random vibration, and shock tests.

  10. Certain characteristics and capture regions of nonlinear vibrating systems

    NASA Technical Reports Server (NTRS)

    Ragulskene, V. L.

    1973-01-01

    Free vibrations of a system and vibrations which are multiples of them in frequency are discussed. The corresponding periodic forced vibrations of the type n/m (n is the number of periods of disturbance between periods of movement and m is the number of periods of movement in one period of disturbance), generated by a harmonic or close to harmonic disturbance, are propagated close to the corresponding curves of the free vibrations and their frequency multiples. It has been proposed that investigation of transitional modes of motion and capture regions be carried out by precise methods in phase space, with the least number of coordinates. Thus, for example, for nonautonomous second order equations (for example, the Duffing equations), in place of three variables (coordinates, velocity, phases), it is proposed to use two: velocity during transition of the coordinate through zero and phase.

  11. Vibration characteristics in a smart bridge model using shape-memory alloy fiber reinforced composite

    NASA Astrophysics Data System (ADS)

    Shimamoto, A.; Zhao, H.; Abe, H.

    2005-05-01

    A smart bridge model was proposed for active control on strength and vibration by changing material properties of shape memory alloy embedded in the bridge structure using TiNi/acrylic composite. A systemic experimental study was carried out to investigate the self-strengthening effect by shape recovery of pre-strained TiNi wires as well as vibration control by stiffness changing with direct electric heating method. The deflection and vibration responses are measured by electric strain gages affixed on the bridge floor on which the model train goes through. From these results, we know the smart bridge model of composite material beam has not only been able to reduce the vibration response, but also change the frequency of the structure. The damping and vibration control for the bridge model is confirmed by the measurement.

  12. Experimental measurements on transverse vibration characteristics of piezoceramic rectangular plates by optical methods

    NASA Astrophysics Data System (ADS)

    Ma, Chien-Ching; Lin, Hsien-Yang

    2005-09-01

    This study provides two non-contact optical techniques to investigate the transverse vibration characteristics of piezoceramic rectangular plates in resonance. These methods, including the amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) and laser Doppler vibrometer (LDV), are full-field measurement for AF-ESPI and point-wise displacement measurement for LDV, respectively. The edges of these piezoceramic rectangular plates may either be fixed or free. Both resonant frequencies and mode shapes of vibrating piezoceramic plates can be obtained simultaneously by AF-ESPI. Excellent quality of the interferometric fringe patterns for the mode shapes is obtained. In the LDV system, a built-in dynamic signal analyzer (DSA) composed of DSA software and a plug-in waveform generator board can provide the piezoceramic plates with the swept-sine excitation signal, whose gain at corresponding frequencies is analyzed by the DSA software. The peaks appeared in the frequency response curve are resonant frequencies. In addition to these optical methods, the numerical computation based on the finite element analysis is used to verify the experimental results. Good agreements of the mode shapes and resonant frequencies are obtained for experimental and numerical results.

  13. Optimization of Training Sets for Neural-Net Processing of Characteristic Patterns from Vibrating Solids

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2001-01-01

    Artificial neural networks have been used for a number of years to process holography-generated characteristic patterns of vibrating structures. This technology depends critically on the selection and the conditioning of the training sets. A scaling operation called folding is discussed for conditioning training sets optimally for training feed-forward neural networks to process characteristic fringe patterns. Folding allows feed-forward nets to be trained easily to detect damage-induced vibration-displacement-distribution changes as small as 10 nm. A specific application to aerospace of neural-net processing of characteristic patterns is presented to motivate the conditioning and optimization effort.

  14. Analysis of radiator characteristics of an antenna array of H-form vibrators

    Microsoft Academic Search

    L. V. Gordienko; L. I. Ponomarev

    1989-01-01

    The theory of wire radiators of intersecting wires is presented in [2, 3] and the possibility of a rigorous approach to the analysis of current distribution and input characteristics of similar radiators is demonstrated. The authors of [4] applied this theory to the analysis of the characteristics of a periodic array of vibrators with posts, which permitted determination of the

  15. Effects of mechanical vibration of the foot sole and ankle tendons on cutaneomuscular responses in man.

    PubMed

    Smith, Andrew C; Mummidisetty, Chaithanya K; Rymer, William Zev; Knikou, Maria

    2013-06-17

    The modulation of cutaneomuscular responses in response to mechanical vibration applied to the foot sole and to the ankle tendons was established in ten healthy subjects. The effects of mechanical vibration applied to the skin adjacent to the tibialis anterior (TA) and Achilles tendons were examined in two subjects. With the subjects seated, mechanical vibration applied to the TA and/or Achilles tendons significantly depressed the cutaneomuscular responses in all subjects, regardless of the frequency (50, 150, 250 Hz) of vibration. Mechanical vibration applied either to the foot sole or to the skin adjacent to the tendons induced no significant effects. The demonstration that mechanical vibration applied to muscle tendons exerts an inhibitory effect on cutaneomuscular responses supports the hypothesis that receptors that mediate body kinesthesia can be used as a vehicle to alter the spinal excitability state. The data suggests that tendon vibration could be utilized in neurological disorders to induce exogenous-mediated potentiation of presynaptic inhibition. PMID:23643990

  16. Experimental measurements and finite element analysis of the coupled vibrational characteristics of piezoelectric shells.

    PubMed

    Huang, Yu-Hsi; Ma, Chien-Ching

    2012-04-01

    Piezoelectric plates can provide low-frequency transverse vibrational displacements and high-frequency planar vibrational displacements, which are usually uncoupled. However, piezoelectric shells can induce three-dimensional coupled vibrational displacements over a large frequency range. In this study, three-dimensional coupled vibrational characteristics of piezoelectric shells with free boundary conditions are investigated using three different experimental methods and finite element numerical modeling. For the experimental measurements, amplitude-fluctuation electronic speckle pattern interferometry (AF-ESPI) is used to obtain resonant frequencies and radial, lateral, and angular mode shapes. This optical technique utilizes a real-time, full-field, non-contact optical system that measures both the natural frequency and corresponding vibration mode shape simultaneously. The second experimental technique used, laser Doppler vibrometry (LDV), is a pointwise displacement measurement method that determines the resonant frequencies of the piezoelectric shell. An impedance analyzer is also used to determine the resonant frequencies of the piezoelectric shell. The experimental results of the resonant frequencies and mode shapes for the piezoelectric shell are verified with a numerical finite element model. Excellent agreement between the experimental and numerical results is found for the three-dimensional coupled vibrational characteristics of the piezoelectric shell. It is noted in this study that there is no coupled phenomenon at low frequencies over which radial modes dominate. However, three-dimensional coupled vibrational modes do occur at high resonant frequencies over which lateral or angular modes dominate. PMID:22547289

  17. Training Data Optimized and Conditioned to Learn Characteristic Patterns of Vibrating Blisks and Fan Blades

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    2001-01-01

    At the NASA Glenn Research Center, we have been training artificial neural networks to interpret the characteristic patterns (see the leftmost image) generated from electronic holograms of vibrating structures. These patterns not only visualize the vibration properties of structures, but small changes in the patterns can indicate structural changes, cracking, or damage. Neural networks detect these small changes well. Our objective has been to adapt the neural-network, electronic-holography combination for inspecting components in Glenn's Spin Rig.

  18. Free vibration and forced harmonic response of an electrorheological fluid-filled sandwich plate

    NASA Astrophysics Data System (ADS)

    Hasheminejad, Seyyed M.; Maleki, Mohsen

    2009-05-01

    A dynamic model for the electric field-dependent steady-state vibrational response of a rectangular sandwich plate with a tunable electrorheological fluid (ERF) interlayer, subjected to a general harmonic transverse excitation, is developed. Hamilton's principle and the classical thin plate theory are applied to derive a set of fully coupled dynamic equations of motion along with the associated general boundary conditions. Assuming simply-supported edge conditions, the displacement components of the ERF-based sandwich plate are postulated by means of generalized double Fourier series with frequency-dependent coefficients. The natural frequencies and modal loss factors are subsequently determined by solving a complex eigenvalue problem. Analytical solutions are also obtained for the forced vibration characteristics of the adaptive structure under different external transverse excitations of varying frequency (0-300 Hz) and applied electric field strength (0-3.5 kV mm-1). Primary attention is focused on the effects of electric field magnitude, geometric aspect ratio, loading type, and ER core layer thickness on the dynamic characteristics of the sandwich plate. In addition, an effort is made to find the optimal electric field which yields minimized vibration amplitude for each excitation frequency. Limiting cases are considered and good agreements with the numerical solutions available in the literature are obtained.

  19. Evaluation of human response to structural vibrations induced by sonic booms

    NASA Technical Reports Server (NTRS)

    Sutherland, Louis C.; Czech, J.

    1992-01-01

    The topic is addressed of building vibration response to sonic boom and the evaluation of the associated human response to this vibration. An attempt is made to reexamine some of the issues addressed previously and to offer fresh insight that may assist in reassessing the potential impact of sonic boom over populated areas. Human response to vibration is reviewed first and a new human vibration response criterion curve is developed as a function of frequency. The difference between response to steady state versus impulsive vibration is addressed and a 'vibration exposure' or 'vibration energy' descriptor is suggested as one possible way to evaluate duration effects on response to transient vibration from sonic booms. New data on the acoustic signature of rattling objects are presented along with a review of existing data on the occurrence of rattle. Structural response to sonic boom is reviewed and a new descriptor, 'Acceleration Exposure Level' is suggested which can be easily determined from the Fourier Spectrum of a sonic boom. A preliminary assessment of potential impact from sonic booms is provided in terms of human response to vibration and detection of rattle based on a synthesis of the preceding material.

  20. The vibrational startle response of the desert locust Schistocerca gregaria.

    PubMed

    Friedel, T

    1999-08-01

    Substratum vibrations elicit a fast startle response in unrestrained quiescent desert locusts (Schistocerca gregaria). The response is graded with stimulus intensity and consists of a small, rapid but conspicuous movement of the legs and body, but it does not result in any positional change of the animal. With stimuli just above threshold, it begins with a fast twitch of the hindlegs generated by movements of the coxa-trochanter and femur-tibia joints. With increasing stimulus intensity, a rapid movement of all legs may follow, resulting in an up-down movement of the whole body. The magnitude of both the hindleg movement and electromyographic recordings from hindleg extensor and flexor tibiae muscles increases with stimulus amplitude and reaches a plateau at vibration accelerations above 20 m s(-)(2) (peak-to-peak). Hindleg extensor and flexor tibiae muscles in unrestrained animals are co-activated with a mean latency of 30 ms. Behavioural thresholds are as low as 0. 47 m s(-)(2) (peak-to-peak) at frequencies below 100 Hz but rise steeply above 200 Hz. The response habituates rapidly, and inter-stimulus intervals of 2 min or more are necessary to evoke maximal reactions. Intracellular recordings in fixed (upside-down) locusts also revealed co-activation of both flexor and extensor motor neurones with latencies of approximately 25 ms. This shows that the neuronal network underlying the startle movement is functional in a restrained preparation and can therefore be studied in great detail at the level of identified neurones. PMID:10409486

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

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

    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.

  2. Intracellular Dynamic Response Characteristics of Pineal Photoreceptors

    Microsoft Academic Search

    Y. Morit; K. Segi; M. Samejima; T. Nakamura

    1984-01-01

    The dynamic properties of single pineal photoreceptors of Lampetra japonica were measured intracellularly by sinusoidal modulated light stimuli. According to the Bode plots the response amplitude and phase characteristic of pineal photoreceptors could be simulated by a linear model with 4th-order transfer function. A similarity to the receptor response of the vertebrate lateral eye was observed.

  3. The acoustic behaviour of the bushcricket Tettigonia cantans I. Behavioural responses to sound and vibration.

    PubMed

    Latimer, W; Schatral, A

    1983-05-01

    The responses of Tettigonia cantans to species-specific song and substrate conducted vibration have been tested under three experimental regimes. When directional cues are adequate the sound source can be located by audition alone; where such cues fail to provide sufficient information then vibration signals become of value. In two-choice experiments vibrating substrates are preferred by both males and females moving towards the sound source. In multiple-choice experiments Tettigoniids may either detect and follow vibration gradients or the direction of the bending waves coming from the vibration source to orientate towards a conspecific. PMID:24897315

  4. Some constructions and characteristics of rod-type piezoelectric ultrasonic motors using longitudinal and torsional vibrations

    Microsoft Academic Search

    Yoshiro Tomikawa; Kazunari Adachi; Manabu Aoyagi; Tadaatsu Sagae; Takehiro Takano

    1992-01-01

    Ultrasonic motors using longitudinal and torsional motions of rod vibrators have previously been proposed. Several motor constructions, whose forms are different from the previous ones, are proposed and their characteristics are experimentally examined in order to develop the ultrasonic motors of this type; that is, they are expected to have much different uses, according to how their forms are modified.

  5. A study on kinetic characteristics of a cylindrical moving coil linear DC motor for a vibrator

    Microsoft Academic Search

    M. Watada; Y. Fukuya; D. Ebihara; T. Okada; T. Takura

    1995-01-01

    A cylindrical moving coil linear DC motor has been developed for a vibrator which is driven at a high frequency with a short stroke. The actuator is supposed to be driven using resonances of spring plates which are placed at the end of the permanent magnet and the armature, respectively. This paper describes the investigation of stroke to frequency characteristics

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

    SciTech Connect

    Li, Junying; Zhu, Yong, E-mail: yongzhu@cqu.edu.cn; Wang, Ning; Zhang, Jie [The Key Laboratory of Optoelectronic Technology and System, Education Ministry of China, Chongqing University, Chongqing, 400044 (China); Wang, Xin [State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu, 610054 (China)

    2014-07-14

    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.

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

    PubMed

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

    2014-12-25

    In this study, a recall experiment and a recognition experiment were designed to assess the human wrist's short-term memory characteristics of tactile perception on vibration intensity, by using a novel homemade vibrotactile display device based on the spatiotemporal combination vibration of multiple micro vibration motors as a test device. Based on the obtained experimental data, the short-term memory span, recognition accuracy and reaction time of vibration intensity were analyzed. From the experimental results, some important conclusions can be made: (1) The average short-term memory span of tactile perception on vibration intensity is 3 ± 1 items; (2) The greater difference between two adjacent discrete intensities of vibrotactile stimulation is defined, the better average short-term memory span human wrist gets; (3) There is an obvious difference of the average short-term memory span on vibration intensity between the male and female; (4) The mechanism of information extraction in short-term memory of vibrotactile display is to traverse the scanning process by comparison; (5) The recognition accuracy and reaction time performance of vibrotactile display compares unfavourably with that of visual and auditory. The results from this study are important for designing vibrotactile display coding scheme. PMID:25516517

  8. Neural-Net Processing of Characteristic Patterns From Electronic Holograms of Vibrating Blades

    NASA Technical Reports Server (NTRS)

    Decker, Arthur J.

    1999-01-01

    Finite-element-model-trained artificial neural networks can be used to process efficiently the characteristic patterns or mode shapes from electronic holograms of vibrating blades. The models used for routine design may not yet be sufficiently accurate for this application. This document discusses the creation of characteristic patterns; compares model generated and experimental characteristic patterns; and discusses the neural networks that transform the characteristic patterns into strain or damage information. The current potential to adapt electronic holography to spin rigs, wind tunnels and engines provides an incentive to have accurate finite element models lor training neural networks.

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Gohlka, Werner

    1943-01-01

    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.

  11. Hydrologic response of underground reservoirs to seismic vibrations

    NASA Astrophysics Data System (ADS)

    Kocharyan, G. G.; Vinogradov, E. A.; Gorbunova, E. M.; Markov, V. K.; Markov, D. V.; Pernik, L. M.

    2011-12-01

    The response of the water level in wells to seismic impacts from remote earthquakes and explosions are analyzed. It is shown that in most cases the magnitude of the postseismic change in the water level scales as a square root of the amplitude of the deformation wave. The intensity of persistent changes averages a dynamical deformation of 1-5 cm/?strain. Noticeable deviations from the mentioned range are possible, depending on the particular structural features of the layer. The possibility of the destruction of poorly permeable barriers, which are formed in the fractures in rocks during precipitation of microparticles, by dynamical pulses is studied in laboratory experiments. It is shown that the fracture's permeability of the rock may considerably increase even in the range of low-amplitude vibrations which are unlikely to cause a failure of the rock or a growth of the existing cracks in response to the passage of a seismic wave. It is established that the effect may progressively accumulate under the prolonged action of seismic impacts. The change in the number of open cracks and the increase in their effective permeability may bring about fluid migration and variations in pore pressure and, consequently, change the whole range of the local mechanical properties of the rock.

  12. Response of finger circulation to energy equivalent combinations of magnitude and duration of vibration

    PubMed Central

    Bovenzi, M; Lindsell, C; Griffin, M

    2001-01-01

    OBJECTIVES—To investigate the acute response of finger circulation to vibration with different combinations of magnitude and duration but with the same "energy equivalent" acceleration magnitude according to current standards for hand transmitted vibration.?METHODS—Finger skin temperature (FST) and finger blood flow (FBF) were measured in the middle fingers of both hands of 10 healthy men who had not used hand held vibrating tools regularly. With a static load of 10 N, the right hand was exposed to 125 Hz vibration with the following unweighted root mean square (rms) acceleration magnitudes and durations of exposure: 44 m/s2 for 30 minutes; 62 m/s2 for 15 minutes; 88 m/s2 for 7.5 minutes; 125 m/s2 for 3.75 minutes; and 176 m/s2 for 1.88 minutes. These vibration exposures produce the same 8 hour energy equivalent frequency weighted acceleration magnitude (~1.4 m/s2 rms) according to international standard ISO 5349 (1986). Finger circulation was measured in both the right (vibrated) and the left (non-vibrated) middle fingers before application of the vibration, and at fixed intervals during exposure to vibration and during a 45 minute recovery period.?RESULTS—The FST did not change during exposure to vibration, whereas vibration with any combination of acceleration magnitude and duration produced significant percentage reductions in the FBF of the vibrated finger compared with the FBF before exposure (from ?40.1% (95% confidence interval (95% CI) ?24.3% to ?57.2%) to ?61.4% (95% CI ?45.0% to ?77.8%). The reduction in FBF during vibration was stronger in the vibrated finger than in the non-vibrated finger. Across the five experimental conditions, the various vibration stimuli caused a similar degree of vasoconstriction in the vibrated finger during exposure to vibration. There was a progressive decrease in the FBF of both fingers after the end of exposure to vibration with acceleration magnitudes of 44 m/s2 for 30 minutes and 62 m/s2 for 15 minutes. Significant vasoconstrictor after effects were not found in either finger after exposure to any of the other vibration stimuli with greater acceleration magnitudes for shorter durations.?CONCLUSIONS—For the range of vibration magnitudes investigated (44 to 176 m/s2 rms unweighted; 5.5 to 22 m/s2 rms when frequency weighted according to ISO 5349), the vasoconstriction during exposure to 125 Hz vibration was independent of vibration magnitude. The after effect of vibration was different for stimuli with the same energy equivalent acceleration, with greater effects after longer durations of exposure. The energy equivalent acceleration therefore failed to predict the acute effects of vibration both during and after exposure to vibration. Both central and local vasoregulatory mechanisms are likely to be involved in the response of finger circulation to acute exposures to 125 Hz vibration.???Keywords: finger circulation; energy equivalent acceleration magnitude; vibration frequency; magnitude; and duration PMID:11171932

  13. City Dweller Responses to Multiple Stressors Intruding into Their Homes: Noise, Light, Odour, and Vibration

    PubMed Central

    Pedersen, Eja

    2015-01-01

    Urban densification increases exposure to noise, light, odour, and vibration in urban dwellings. Exposure from combined environmental stressors intruding into the home could increase the risk of adverse effects on wellbeing, even when the exposure is at a relatively low level. This study assesses the prevalence of annoyance with a combination of potential environmental stressors common in urban areas and the association with wellbeing. A questionnaire was sent by mail to residents in five areas in Halmstad (Sweden) with similar socioeconomic and housing characteristics but different exposure (response rate 56%; n = 385). Of the respondents, 50% were annoyed to some degree by at least one of the suggested stressors, most commonly by noise and vibration from local traffic. Structural equation modelling showed that annoyance led to lowered quality of life via the mediating construct residential satisfaction, which in turn was influenced by place attachment and perceived restoration possibilities in the dwelling. Stress had a negative impact on quality of life, but was not directly correlated to annoyance. Stress was however correlated with sensitivity. The findings suggest that dose-response relationships for environmental stressors should be studied in a broader context of environmental and individual factors. Also relatively low levels of exposure should be mitigated, especially if several stressors are present. PMID:25794188

  14. Vibration durability modeling and dynamic response analysis of PBGA mixed solder joints

    Microsoft Academic Search

    Zhou Bin; Qiu Baojun; En Yunfei

    2010-01-01

    Along with more and more use of high density plastic ball grid array (PBGA) in portable electronic products and military electronic equipments, the vibration fatigue reliability of solder joints for PBGA becomes a critical concern. In this paper, a quarter 3D symmetric model was developed by ANSYS software, then modal analysis of PCBA assembly and random vibration response analysis of

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

    Microsoft Academic Search

    Shuangyin Zhang; Lei Wang; Youshi Hong

    2010-01-01

    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

  16. LP compressor blade vibration characteristics at starting conditions of a 100 MW heavy-duty gas turbine

    Microsoft Academic Search

    An Sung Lee; Alexandre F. Vedichtchev

    2004-01-01

    In this paper are presented the blade vibration characteristics at the starting conditions of the low pressure multistage\\u000a axial compressor of heavy-duty 100 MW gas turbine. Vibration data have been collected through strain gauges during aerodynamic\\u000a tests of the model compressor. The influences of operating modes at the starting conditions are investigated upon the compressor\\u000a blade vibrations. The exciting mechanisms

  17. Evaluation of obstructive lung disease with vibration response imaging.

    PubMed

    Guntupalli, Kalpalatha K; Reddy, Raghu M; Loutfi, Rabih H; Alapat, Philip M; Bandi, Venkata D; Hanania, Nicola A

    2008-12-01

    As optimal treatment and prognosis differ between asthma and COPD, a new diagnostic approach to differentiating between the two disorders would be clinically desirable. We evaluated the utility of vibration response imaging in differentiating between asthma and COPD. Sixty-six subjects with asthma or COPD were recorded, before and after the administration of a short-acting bronchodilator, using a computerized lung sound analysis device. Gray-scale images of breath sound distribution in the lungs, quantitative data in breath sound graphs (timing, amplitude) and automatic crackle and wheeze detection programs were used to differentiate between asthma and COPD subjects. Imaging data were compared with the clinical diagnosis, made by the standard methods (medical history, physical examination, and spirometric indices). Blinded evaluation of images demonstrated a significantly higher rate of improvement in image dynamics, shape and overall improvement following bronchodilator in subjects with asthma compared with those with COPD. Quantitative data showed distinct patterns in timing and amplitude for these two pathologies. Combined analyses based on qualitative image evaluation and quantitative data demonstrated an overall 85% accuracy (84% for asthma, 86% for COPD) in differentiating between asthma and COPD. Combined qualitative and quantitative evaluations of lung sounds are quite sensitive in distinguishing between lung sound recordings of COPD and asthma individuals. Lung sound features of synchronization in timing and intensity provide objective data that may further differentiate these two airway disorders. PMID:19085584

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

    NASA Astrophysics Data System (ADS)

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

    1993-03-01

    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.

  19. Improvement of L\\/UL performance using load\\/unload mechanism control considering disk vibration characteristics

    Microsoft Academic Search

    Kyoung-Su Park; Jeong-Il Chun; Yong-Hyun Lee; No-Cheol Park; Hyun-Seok Yang; Young-Pil Park

    2004-01-01

    Load\\/unload dynamic characteristics are affected by various parameters; load\\/unload speed, disk rotating speed, disk vibration and so on. The effect of load\\/unload process on various parameters was investigated by the experiment. As a result of experiment, the load performance was found to be better for lower load speed and disk rpm. On the other hand, it was confirmed to be

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

    Microsoft Academic Search

    D. M. Lauzon; V. R. Murthy

    1993-01-01

    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

  1. RESEARCH ON VIBRATION CHARACTERISTICS BETWEEN HUMAN BODY AND SEAT, STEERING WHEEL, AND PEDALS (EFFECTS OF SEAT POSITION ON RIDE COMFORT)

    Microsoft Academic Search

    S. Nishiyama; N. Uesugi; T. Takeshima; Y. Kano; H. Togii

    2000-01-01

    Experimental results are presented of the vibrational characteristics of the automotive subsystem comprising the human body, seat, steering wheel and pedals. The magnitude of the vibrations transferred to a driver from the seat, steering wheel and pedals have been measured with both sinusoidal and random excitations in the vertical direction at frequencies up to 20 Hz. Measurement points were located

  2. Damage detection in composite structures using vibration response under stochastic excitation

    Microsoft Academic Search

    Zhichun Yang; Le Wang; Hui Wang; Yan Ding; Xiaojuan Dang

    2009-01-01

    The investigations in damage detection methods based on vibration response are reviewed according to two categories, i.e. model-based damage detection method (MBDDM) and non-model-based damage detection method (NMBDDM). Then a new concept of inner product vector (IPV) is introduced using the cross correlation function of the measured vibration responses of the structure, and the corresponding damage detection method is proposed

  3. Sensitivity analysis of free vibration characteristics of an in situ railway concrete sleeper to variations of rail pad parameters

    NASA Astrophysics Data System (ADS)

    Kaewunruen, Sakdirat; Remennikov, Alex M.

    2006-11-01

    The vibration of in situ concrete sleepers in a railway track structure is a major factor causing cracking of prestressed concrete sleepers and excessive railway track maintenance cost. Not only does the ballast interact with the sleepers, but the rail pads also take part in affecting their free vibration characteristics. This paper presents a sensitivity analysis of free vibration behaviors of an in situ railway concrete sleeper (standard gauge sleeper), incorporating sleeper/ballast interaction, subjected to the variations of rail pad properties. Through finite element analysis, Timoshenko-beam and spring elements were used in the in situ railway concrete sleeper modeling. This model highlights the influence of rail pad parameters on the free vibration characteristics of in situ sleepers. In addition, information on the first five flexural vibration modes indicates the dynamic performance of railway track when using different types of rail pads, as it plays a vital role in the cracking deterioration of concrete sleepers.

  4. Vibration Response as an Indicator of Ground Fall Hazards in Mining: An Investigation Using Laser Doppler Vibrometry

    NASA Astrophysics Data System (ADS)

    Swanson, P. L.; Rettkowski, J. D.; Caley, A. B.

    2003-12-01

    Unexpected falls of ground are one of the leading sources of injuries and fatalities in U. S. underground mines. A primary means of assessing mine-roof integrity is the age-old method of roof sounding where a miner taps on the roof and listens to the resulting seismically coupled acoustic response. Impacts to loose, hazardous blocks of rock generally produce a hollow drummy sound that is anomalously low in frequency and long in duration compared to sounds from competent rock. In this study, a noncontact laser Doppler vibrometry (LDV) method is used to record vibrations on rock surfaces to (i) evaluate the feasibility of remotely detecting hazardous ground from safe positions and (ii) delineate the fundamental, and little-studied, mechanical processes attending such gravity-driven failures. During the technique development stage, measurements were obtained on various rock outcrops and other structures with known defects; these included single-point and two-dimensional array recordings. Excitation sources included local and remote impacts, and ambient and forced vibrations. Consistent with predictions from simple models of elastic blocks coupled to solid ground through low-stiffness interfaces, loose rocks were effectively delineated with simple broadband RMS measures of elevated particle velocity. Other narrow-band spectral measures were also investigated and observed to be sensitive to block geometry, interface boundary conditions, and excitation source characteristics. In most of the experiments, loose blocks could be identified, in a comparative sense, even without compensating for the attendant vibration of the LDV. To deliver useful vibration response information to miners and others exposed to these hazards, two options are being explored: (i) development of 2-D maps of vibration response superimposed on target images and (ii) conversion of single-point LDV output into audible signals for use in a qualitative comparative mode.

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

    SciTech Connect

    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

    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.

  6. Vibrational characteristics of graphene sheets elucidated using an elastic network model.

    PubMed

    Kim, Min Hyeok; Kim, Daejoong; Choi, Jae Boong; Kim, Moon Ki

    2014-08-01

    Recent studies of graphene have demonstrated its great potential for highly sensitive resonators. In order to capture the intrinsic vibrational characteristics of graphene, we propose an atomistic modeling method called the elastic network model (ENM), in which a graphene sheet is modeled as a mass-spring network of adjacent atoms connected by various linear springs with specific bond ratios. Normal mode analysis (NMA) reveals the various vibrational features of bi-layer graphene sheets (BLGSs) clamped at two edges. We also propose a coarse-graining (CG) method to extend our graphene study into the meso- and macroscales, at which experimental measurements and synthesis of graphene become practical. The simulation results show good agreement with experimental observations. Therefore, the proposed ENM approach will not only shed light on the theoretical study of graphene mechanics, but also play an important role in the design of highly-sensitive graphene-based resonators. PMID:24939373

  7. ATOMIC AND MOLECULAR PHYSICS: Ultrafast multiplex CARS investigation of vibrational characteristics in chloroform and PMMA

    NASA Astrophysics Data System (ADS)

    Wang, Ying-Hui; Peng, Ya-Jing; He, Xing; Song, Yun-Fei; Yang, Yan-Qiang

    2009-04-01

    This paper demonstrates the femtosecond time-resolved coherent anti-Stokes Raman scattering by using folded BOXCARS geometry where an ultrashort broadband coherent white light continuum was used as Stokes pulse, and carries out the non-contact detection at long distance. The CARS signal is so easy to be detected that it can be seen even by nude eye. The C-H bonds of chloroform or PMMA were detected and the vibration modes belonging to the side chain and the main chain in PMMA were also compared. Their vibrational characteristics involved decay process and quantum beating were discussed. This modified CARS experimental technique could make up the deficiency of traditional CARS technique.

  8. Vibration manual

    NASA Technical Reports Server (NTRS)

    Green, C.

    1971-01-01

    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.

  9. Evaluation of human response to structural vibration induced by sonic boom

    NASA Technical Reports Server (NTRS)

    Sutherland, L. C.; Czech, J.

    1992-01-01

    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.

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

    Microsoft Academic Search

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

    1980-01-01

    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

  11. Variation in Neuromuscular Responses during Acute Whole-Body Vibration Exercise

    Microsoft Academic Search

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

    2007-01-01

    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

  12. Head position-based electrotactile tongue biofeedback affects postural responses to Achilles tendon vibration in humans

    Microsoft Academic Search

    Nicolas Vuillerme; Rémy Cuisinier

    2008-01-01

    The purpose of the present experiment was to investigate whether postural responses to ankle proprioceptive perturbation Achilles\\u000a tendon vibration were affected by the availability of augmented sensory information about head orientation\\/motion with respect\\u000a to gravitational vertical, i.e., normally provided by the vestibular system. To achieve this goal, ten standing subjects were\\u000a exposed to Achilles tendon vibration in two No Biofeedback

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    PubMed Central

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

    2009-01-01

    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

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

    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.

  16. Study on vibration characteristics of the shaft system for a dredging pump based on FEM

    NASA Astrophysics Data System (ADS)

    Zhai, L. M.; Qin, L.; Liu, C. Y.; Liu, X.; He, L. Y.; He, Y.; Wang, Z. W.

    2012-11-01

    The dynamic characteristics of the shaft system for a dredging pump were studied with the Finite Element Method (FEM) by SAMCEF ROTOR. At first, the influence of the fluid-solid coupling interaction of mud water and impeller, water sealing and pump shaft on the lateral critical speeds were analyzed. The results indicated that the mud water must be taken into consideration, while the water sealing need not to. Then the effects of radial and thrust rolling bearings on the lateral critical speeds were discussed, which shows that the radial bearing close to the impeller has greatest impact on the 1st order critical speed. At last, the upper and lower limits of the critical speeds of lateral, axial and torsional vibration were calculated. The rated speed of the dredging pump was far less than the predicted critical speed, which can ensure the safe operation of the unit. Each vibration mode is also shown in this paper. This dynamic analysis method offers some reference value on the research of vibration and stability of the shaft system in dredging pump.

  17. Neurocognitive responses to a single session of static squats with whole body vibration.

    PubMed

    Amonette, William E; Boyle, Mandy; Psarakis, Maria B; Barker, Jennifer; Dupler, Terry L; Ott, Summer D

    2015-01-01

    The purpose of this study was to determine if the head accelerations using a common whole body vibration (WBV) exercise protocol acutely reduced neurocognition in healthy subjects. Second, we investigated differential responses to WBV plates with 2 different delivery mechanisms: vertical and rotational vibrations. Twelve healthy subjects (N = 12) volunteered and completed a baseline (BASE) neurocognitive assessment: the Immediate Postconcussion Assessment and Cognitive Test (ImPACT). Subjects then participated in 3 randomized exercise sessions separated by no more than 2 weeks. The exercise sessions consisted of five 2-minute sets of static hip-width stance squats, with the knees positioned at a 45° angle of flexion. The squats were performed with no vibration (control [CON]), with a vertically vibrating plate (vertical vibration [VV]), and with a rotational vibrating plate (rotational vibration [RV]) set to 30 Hz with 4 mm of peak-to-peak displacement. The ImPACT assessments were completed immediately after each exercise session and the composite score for 5 cognitive domains was analyzed: verbal memory, visual memory, visual motor speed, reaction time, and impulse control. Verbal memory scores were unaffected by exercise with or without vibration (p = 0.40). Likewise, visual memory was not different (p = 0.14) after CON, VV, or RV. Significant differences were detected for visual motor speed (p = 0.006); VV was elevated compared with BASE (p = 0.01). There were no significant differences (p = 0.26) in reaction time or impulse control (p = 0.16) after exercise with or without vibration. In healthy individuals, 10 minutes of 30 Hz, 4-mm peak-to-peak displacement vibration exposure with a 45° angle of knee flexion did not negatively affect neurocognition. PMID:25536489

  18. The Effect of Surface Wave Propagation on Neural Responses to Vibration in Primate Glabrous Skin

    E-print Network

    Elias, Damian Octavio

    The Effect of Surface Wave Propagation on Neural Responses to Vibration in Primate Glabrous Skin relies on the response of large populations of receptors distributed across the skin, we seek to characterize how a mechanical deformation of the skin at one location affects the skin at another. To this end

  19. Micro-meter Crack Response to Rock Blast Vibrations, Wind Gusts & Weather Effects

    E-print Network

    Micro-meter Crack Response to Rock Blast Vibrations, Wind Gusts & Weather Effects C. H. Dowding,1 to rock blasting- and wind gust- excitation are compared to those induced by long term climatological to measure crack expansion and contraction. Crack responses to 48 to 64 km/hr (30- 40 mph) wind gusts were

  20. Vibration characteristics of thin rotating cylindrical shells with various boundary conditions

    NASA Astrophysics Data System (ADS)

    Sun, Shupeng; Chu, Shiming; Cao, Dengqing

    2012-08-01

    An analysis is presented for the vibration characteristics of thin rotating cylindrical shells with various boundary conditions by use of Fourier series expansion method. Based on Sanders' shell equations, the governing equations of motion which take into account the effects of centrifugal and Coriolis forces as well as the initial hoop tension due to rotating are derived. The displacement field is expressed as a product of Fourier series expressions which represents the axial modal displacements and trigonometric functions which represents the circumferential modal displacements. Stokes' transformation is employed to derive the derivatives of the Fourier series expressions. Then, through the process of formula derivation, an explicit expression of the exact frequency equation can be obtained for a thin rotating cylinder with classical boundary conditions of any type. Once the frequency equation has been determined, the frequencies are calculated numerically. To validate the present analysis, comparisons between the results of the present method and previous studies are performed and very good agreement is achieved. Finally, the method is applied to investigate the vibration characteristics of thin rotating cylindrical shells under various boundaries, and the results are presented.

  1. Design and Operation of a Vibration-Acoustic-Thermal Apparatus for Identifying Variations in Free and Forced Response of Sandwich Panels Due to Combined Loading

    NASA Astrophysics Data System (ADS)

    Ellmer, Claudia; Adams, Douglas E.; White, Jonathan R.; Jata, Kumar

    2008-02-01

    Combined vibration, thermal, and acoustic environments cause significant changes in the free and forced response characteristics of spacecraft metallic, ceramic, and carbon thermal protection systems, exhaust wash structures in fixed wing aircraft, and ground vehicle components exposed to blast loading. When structural components become damaged, the effects of combined loads are even more apparent on the structural response. A new combined vibration-acoustic-thermal apparatus designed to simultaneously expose specimens up to 4' by 4' with 10 g vibration up to either 100 Hz or 1 inch displacement vibrations, 140 dB acoustic pressures, and >400 °F temperatures will first be described in this paper. Then observations from experiments conducted on a sandwich metallic panel exposed to thermal loads will be described. Modal impact and active sensor data will be utilized to extract frequency response function models that change as a function of the loading. These frequency response models indicate significant changes in the free response properties of the panel. For example, it will be shown that temperature changes cause the resonant frequencies of the panel to decrease resulting in higher response amplitudes. Likewise, acoustic pressure loads distributed across the panel will be shown to change as a function of temperature.

  2. Study the vibration and dynamic response of the dipole girder system for CSNS/RCS

    E-print Network

    Renhong, Liu; JunSong, Zhang; GuangYuan, Wang

    2015-01-01

    China Spallation Neutron Source is a high intensity proton accelerator based facility, and its accelerator complex includes two main parts an H- linac and a rapid cycling synchrotron. The RCS accumulates the 80MeV proton beam, and accelerates it to 1.6GeV, with a repetition rate of 25Hz. The dipole of the CSNS RCS is operated at a 25 Hz sinusoidal alternating current which causes severe vibrate. The vibration will influence the long term safety and reliable operation of the magnet. The dipole of the CSNS RCS is an active vibration equipment which is different from the ground vibration accelerator. It is very important to design and study the dynamic characteristics of the dipole girder system. This paper takes the dipole and girder as a specific model system, a method for studying the dynamic characteristics of the system is put forward by combining theoretical calculation with experimental testing. The modal parameters with and without vibration isolator of the dipole girder system are obtain through ANSYS s...

  3. Modal Analysis and Study of the Vibration Characteristics of the Thermoelectric Modules of Vehicle Exhaust Power-Generation Systems

    NASA Astrophysics Data System (ADS)

    Chen, Gang; Mu, Yu; Zhai, Pengcheng; Yu, Rui; Li, Guodong; Zhang, Qingjie

    2014-06-01

    Thermoelectric (TE) materials and modules are important components of vehicle exhaust power-generation systems. The road and the engine, the main sources of vibration of TE modules, have substantial effects on the vibration characteristics of TE modules. In this work, modal analysis and the vibration characteristics of TE modules were investigated in detail. On the basis of the TE modules and their service environment, simulations for modal analysis were performed by use of the finite-element method, and the natural frequencies and mode shapes of the TE modules were obtained. The numerical results were used to compare the natural frequencies of TE modules under different contact stiffness with the range of excitation frequencies of road and engine, in an attempt to prevent severe resonance. The effects on the vibration characteristics of geometric dimensions, service temperature, and thermal stress of the TE modules are also discussed in detail. The results reveal the vibration characteristics of the TE modules and provide theoretical guidance for structure optimization in the design of vehicle exhaust power-generation systems.

  4. Measurement of high solidity vertical axis wind turbine aerodynamic loads under high vibration response conditions

    NASA Astrophysics Data System (ADS)

    McLaren, K.; Tullis, S.; Ziada, S.

    2012-07-01

    A series of full-scale experimental wind tunnel tests were performed to determine the aerodynamic loading behaviour on the airfoils of a high solidity, H-type, vertical axis wind turbine. During the course of this investigation, high amplitude vibration of the turbine was observed over a wide range of test conditions. The primary vibration excitation mechanism was resonance of the dominant whirling mode of the turbine with the operating blade pass frequency. In addition, for a significant number of test cases, resonance of the airfoil support struts at higher frequencies was also observed. This large vibration response resulted in conditions that made it difficult or impossible to measure the underlying aerodynamic loading. As a result, in order to gain a greater understanding of the aerodynamic loading, a vibration isolation methodology was developed to remove the effect of vibration from the measured aerodynamic forces on the blades. This included tests with two different support shaft end conditions over a range of flow velocities from 8 to 11 m/s, and the use of band-stop filtering to remove residual small amplitude vibrations. In this way, an accurate and complete measurement of the aerodynamic loading on the turbine blades could be obtained to better understand the effects of dynamic stall and validate the results of numerical model predictions.

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

    PubMed

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

    2014-11-01

    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 >40 Hz. 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 ~100 MPa, while in the rubbery state the elastic modulus decreased to 20 MPa. 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

  6. Study of T53 engine vibration

    NASA Technical Reports Server (NTRS)

    Walter, T. J.

    1978-01-01

    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.

  7. Lumped Parameter Modeling for Rapid Vibration Response Prototyping and Test Correlation for Electronic Units

    NASA Technical Reports Server (NTRS)

    Van Dyke, Michael B.

    2013-01-01

    Present preliminary work using lumped parameter models to approximate dynamic response of electronic units to random vibration; Derive a general N-DOF model for application to electronic units; Illustrate parametric influence of model parameters; Implication of coupled dynamics for unit/board design; Demonstrate use of model to infer printed wiring board (PWB) dynamics from external chassis test measurement.

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

    SciTech Connect

    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

    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.

  9. Study on the Vibrational Characteristics of a Tube Array Caused by Two-Phase Flow. Part I: Random Vibration

    Microsoft Academic Search

    T. Nakamura; K. Fujita; K. Kawanishi; N. Yamaguchi; A. Tsuge

    1995-01-01

    There are few published papers on the subject of flow-induced vibrations caused by two-phase flow. Experimental data at the high pressure and temperature conditions which would correspond to practical operating conditions are extremely few. Furthermore, the mechanism of the two-phase flow-induced load acting on a tube in a tube array has not yet been explained. This paper presents the experimental

  10. The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling

    E-print Network

    Niu, Yifei; Brenna, Marco; Brenna, Marco; Bortignon, Pier Francesco; Meng, Jie; 10.1103/PhysRevC.85.034314

    2012-01-01

    Although many random-phase approximation (RPA) calculations of the Gamow-Teller (GT) response exist, this is not the case for calculations going beyond the mean-field approximation. We apply a consistent model that includes the coupling of the GT resonance to low-lying vibrations, to nuclei of the $fp$ shell. Among other motivations, our goal is to see if the particle-vibration coupling can redistribute the low-lying GT$^+$ strength that is relevant for electron-capture processes in core-collapse supernova. We conclude that the lowering and fragmentation of that strength are consistent with the experimental findings and validate our model. However, the particle-vibration coupling cannot account for the quenching of the total value of the low-lying strength.

  11. The Gamow-Teller response within Skyrme random-phase approximation plus particle-vibration coupling

    E-print Network

    Yifei Niu; Gianluca Colo; Marco Brenna; Marco Brenna; Pier Francesco Bortignon; Jie Meng

    2012-03-28

    Although many random-phase approximation (RPA) calculations of the Gamow-Teller (GT) response exist, this is not the case for calculations going beyond the mean-field approximation. We apply a consistent model that includes the coupling of the GT resonance to low-lying vibrations, to nuclei of the $fp$ shell. Among other motivations, our goal is to see if the particle-vibration coupling can redistribute the low-lying GT$^+$ strength that is relevant for electron-capture processes in core-collapse supernova. We conclude that the lowering and fragmentation of that strength are consistent with the experimental findings and validate our model. However, the particle-vibration coupling cannot account for the quenching of the total value of the low-lying strength.

  12. Short term response of insulin, glucose, growth hormone and corticosterone to acute vibration in rats.

    NASA Technical Reports Server (NTRS)

    Dolkas, C. B.; Leon, H. A.; Chackerian, M.

    1971-01-01

    Study carried out to obtain some notion of the initial phasing and interactive effects among some hormones known to be responsive to vibration stress. Sprague-Dawley derived rats were exposed to the acute effects of confinement and confinement with lateral (plus or minus G sub y) vibration. The coincident monitoring of glucose, insulin, growth hormone, and corticosterone plasma levels, during and immediately subsequent to exposure to brief low level vibration, exhibits the effects of inhibition of insulin release by epinephrine. The ability of insulin (IRI) to return rapidly to basal levels, from appreciably depressed levels during vibration, in the face of elevated levels of glucose is also shown. Corticosterone responds with almost equal rapidity, but in opposite phase to the IRI. The immuno-assayable growth hormone (IGH) dropped from a basal level of 32 ng/ml to 7.3 ng/ml immediately subsequent to vibration and remained at essentially that level throughout the experiment (60 min). Whether these levels represent a real fall in the rat or whether they merely follow the immuno-logically deficient form is still in question.

  13. Dynamic response characteristic analysis of vehicle frame based on virtual simulation technology

    Microsoft Academic Search

    Hongmin Cai; Peng Du; Hui Liu; Yuan Feng; Xin Zhao; Jian Zhang

    2011-01-01

    Within this paper, the modality of vehicle frame is analyzed by finite element software of ALGOR, and carrying out the first 10 steps natural frequency resonance and vibration model. Using mode of two-degree-of-freedom vehicle vibration builds system's movement differential equation and simulates the frame's vibration by Simulink module of Matlab. Then make a dynamic response simulation for vehicle frame by

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

    PubMed

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

    2010-01-01

    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

  15. Marine riser vibration response determined by modal analysis

    Microsoft Academic Search

    D. W. Dareing; T. Huang

    1980-01-01

    Although marine-riser response calculations are usually based on finite-element or finite-difference methods, Maurer Engineering Inc. and the University of Texas outline a modal analysis method as an alternative approach to calculating marine-riser time-dependent stresses. Instead of representing the derivatives by finite differences in setting up a matrix of algebraic equations, the solution is expressed directly in terms of natural modes

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

    Microsoft Academic Search

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

    1996-01-01

    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

  17. Evaluating Attenuation of Vibration Response using Particle Impact Damping for a Range of Equipment Assemblies

    NASA Technical Reports Server (NTRS)

    Knight, Brent; Parsons, David; Smith, Andrew; Hunt, Ron; LaVerde, Bruce; Towner, Robert; Craigmyle, Ben

    2013-01-01

    Particle dampers provide a mechanism for diverting energy away from resonant structural vibrations. This experimental study provides data from a series of acoustically excited tests to determine the effectiveness of these dampers for equipment mounted to a curved orthogrid panel for a launch vehicle application. Vibration attenuation trends are examined for variations in particle damper fill level, component mass, and excitation energy. A significant response reduction at the component level was achieved, suggesting that comparatively small, strategically placed, particle damper devices might be advantageously used in launch vehicle design. These test results were compared to baseline acoustic response tests without particle damping devices, over a range of isolation and damping parameters. Instrumentation consisting of accelerometers, microphones, and still photography data will be collected to correlate with the analytical results.

  18. Wind-Induced vibration responses of prestressed double-layered spherical latticed shells

    Microsoft Academic Search

    Zhen Zhou; Zhi-ming Li; Shao-ping Meng; Jing Wu

    2011-01-01

    This paper focuses on the wind-induced vibration response of prestressed double-layered spherical latticed shell (PDSLS) structures\\u000a by adopting time-domain analysis method. Welch spectrum analysis method is used to make precision evaluation of power spectrum\\u000a of fluctuating wind speed time history simulated by weighted amplitude wavelet superposition (WAWS) method and linear filtering\\u000a method of auto-regression (AR) model. Results show that the

  19. Psychophysical relationships characterizing human response to whole-body sinusoidal vertical vibration

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

    An experimental investigation determined that the psychophysical relationships between subjective discomfort evaluations to vibratory stimuli and subjective evaluations of the intensity of vibratory stimuli can be expressed in a linear fashion. Furthermore, significant differences were found to exist between discomfort and intensity subjective response for several but not all discrete frequencies investigated. The implication of these results is that ride quality criteria based upon subjective evaluation of vibration intensity should be applied cautiously in the development of criteria for human comfort.

  20. Species-characteristic responses to catnip by undomesticated felids

    Microsoft Academic Search

    J. O. Hill; E. J. Pavlik; G. L. Smith; G. M. Burghardt; P. B. Coulson

    1976-01-01

    Thirty-three large felids belonging to six different species were exposed to catnip and catnip extract. The species-characteristic response to catnip and the sensitivity of the response to various concentrations of catnip were examined. Putative relationships between catnip sensitivity, species range, age, estrous cycle, and behavioral complexity are discussed. The behavioral response to catnip shown by the domestic cat is seen

  1. Response Characteristics of Boiling Water Reactor Generating Units

    Microsoft Academic Search

    Douglas Carroll; Markus Eggenberger; Donald Ewart

    1973-01-01

    The IEEE Working Group on Power Plant Response to Load Changes has encouraged papers on various aspects of plant response. This paper is intended to contribute to the understanding of the response characteristics of a major class of power generation equipment, namely Boiling Water Reactor (BWR) plants as furnished by General Electric Company.

  2. The application of finite element analysis to investigate the vibrational response of a turbine blade under thermosonic excitation

    NASA Astrophysics Data System (ADS)

    Bolu, Gabriel; Gachagan, Anthony; Pierce, Gareth; Barden, Tim

    2013-01-01

    This paper presents a methodology, using a combination of experimental vibration measurements and finite element analysis (FEA), to model the vibrational energy within a turbine blade corresponding to a typical thermosonic inspection scenario. Laser vibrometry measurements were used to determine the steady-state vibration response at several locations on a blade and used to identify the prominent spectral components. These were then used to generate an excitation function for the FEA approach. After validation of the FEA model, the vibration response across the whole blade was simulated. Finally, the predicted displacement field was used to determine the vibrational energy at every point on the blade which was mapped onto a CAD representation of the blade, thereby highlighting areas on the blade that may be below the defect detection threshold.

  3. Forced vibrations of a nonlinear system excited by a centrifugal oscillator with a sloping engine characteristic

    Microsoft Academic Search

    N. P. Plakhtienko; N. V. Lysak

    1980-01-01

    Centrifugal oscillators, of the type used in dynamic analyses of mechanical systems, are powered by low-power engines. Mounted on elastic structures, such engines may give rise to interactions between the translational and rotational motions of the vibrator elements, which lead to unsteady mode shapes of vibration and hinder transition through resonance. In the present paper, these and some other associated

  4. Vibrational characteristics of silver clusters in surface-enhanced Raman scattering

    Microsoft Academic Search

    D. Roy; T. E. Furtak

    1986-01-01

    Evidence from a number of previous experiments is found for Ag-cluster vibrations in enhanced Raman scattering from a Ag surface. By the analysis of the conditions specific to such experiments, the most likely identity of these clusters has been revealed to be Ag4 +. To further confirm this assignment, the vibrational signature of the clusters has been tested in a

  5. A study of the physical characteristics of vibration-induced fretting corrosion

    Microsoft Academic Search

    G. T. Flowers; Fei Xie; M. Bozack; Xin Hai; B. I. Rickett; R. D. Malucci

    2004-01-01

    The objective of this work is to develop a greater understanding of the mechanisms controlling fretting under various vibration conditions. This information is intended to provide a basis for understanding and reducing this potential problem in automotive connectors. Toward this end, an experimental study of connector samples under multi-frequency vibration has been conducted. The primary connector being investigated is a

  6. Numerical study on the vibration characteristics of automobile brake disk and pad

    Microsoft Academic Search

    Xianjie Meng; Guangqiang Wu; Lin He

    2009-01-01

    Based on the review of researches on the vibration and noise related to automobile brake, a four degrees of freedom nonlinear dynamics model of brake disk and pads is established, the stability of vibration system at the equilibrium points is analyzed. Finally the numerical method is taken to study the impacts of brake pressure, shape parameter and the brake disk's

  7. Vibration and Operational Characteristics of a Composite-Steel (Hybrid) Gear

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.; LaBerge, Kelsen E.; DeLuca, Samuel; Pelagalli, Ryan

    2014-01-01

    Hybrid gears have been tested consisting of metallic gear teeth and shafting connected by composite web. Both free vibration and dynamic operation tests were completed at the NASA Glenn Spur Gear Fatigue Test Facility, comparing these hybrid gears to their steel counterparts. The free vibration tests indicated that the natural frequency of the hybrid gear was approximately 800 Hz lower than the steel test gear. The dynamic vibration tests were conducted at five different rotational speeds and three levels of torque in a four square test configuration. The hybrid gears were tested both as fabricated (machined, composite layup, then composite cure) and after regrinding the gear teeth to the required aerospace tolerance. The dynamic vibration tests indicated that the level of vibration for either type of gearing was sensitive to the level of load and rotational speed.

  8. Real distributed vibration sensing with high frequency response based on pulse pair

    NASA Astrophysics Data System (ADS)

    He, Qian; Zhu, Tao; Xiao, Xianghui; Diao, Dongmei; Huang, Wei; Bao, Xiaoyi

    2014-05-01

    In conventional phase-sensitive optical time domain reflectometry (?-OTDR), the length of sensing fiber mainly determines the repetition rate of probe light pulses, which limits the extent of detectable frequency range. Moreover, averaging method, which is adopted to enhance the location signal-to-noise-ratio (SNR), further decreases the maximum detectable frequency. This paper demonstrates a distributed vibration sensor with satisfied location SNR and extended frequency response range by using a probe pulse pair with a frequency difference. Experimental results show that this method is able to break the trade-off between the given sensing fiber length and the traditional maximum detectable frequency response of ?-OTDR system.

  9. 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)

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

    2014-10-01

    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.

  10. Response characteristics of visual altitude control system in Bombus terrestris.

    PubMed

    Tanaka, Kensaku; Kawachi, Keiji

    2006-11-01

    Frequency response characteristics of bumblebees to vertical visual oscillations were measured and analyzed. We measured the vertical force of the bees at four oscillation frequencies (0.9, 1.8, 3.6 and 7.4 Hz), and summarized their response characteristics in terms of amplitude and phase differences. The amplitude was almost constant throughout the examined frequency domain, whereas the phase gradually lagged with increasing frequency. In order to view the relationship between the input (visual oscillation) and output (response of the bee) more clearly as a control system, we compared them in the same dimension; we calculated hypothetical positions of the tethered bees on the basis of the measured variation in the vertical force, and compared them with the visual stripe positions. The resultant gain and phase data were plotted on a Bode plot. A transfer function was identified from the Bode plot, revealing that the response characteristics of the measured system could be represented as a simple expression. The dynamic control characteristics of the bumblebees were analyzed on the basis of the frequency response data. First, we showed that the measured system possesses a substantial stability margin. This means that the control system has substantial damping characteristics, and was suitable for stable flight control. In addition, our results showed that the measured bumblebee system possesses superior steady state and quick-response characteristics in comparison with a human pilot-vehicle system. Such excellence in both the steady state and transient characteristics (i.e. damping and quick response characteristics) provide the evidence that bumblebees can effectively control their flight with stability and maneuverability. PMID:17079723

  11. A technical feasibility study of dornase alfa delivery with eFlow® vibrating membrane nebulizers: aerosol characteristics and physicochemical stability.

    PubMed

    Scherer, Thomas; Geller, David E; Owyang, Laura; Tservistas, Marcus; Keller, Manfred; Boden, Norbert; Kesser, Kenneth C; Shire, Steven J

    2011-01-01

    Dornase alfa (Pulmozyme®) is an inhaled mucus-active drug that decreases viscoelasticity of sputum in vitro, improves lung function and reduces respiratory exacerbations in cystic fibrosis (CF) patients of 5 years age and older. The regulatory approval of dornase alfa 15 years ago stipulated that only certain jet nebulizer-compressor combinations should be used to deliver the drug. Since that time there have been significant advances in aerosol delivery technology, including development of electronic perforated vibrating membrane devices. Three independent laboratories studied aerosol characteristics, nebulization time, dose delivery, and stability of dornase alfa after nebulization to determine the feasibility of using perforated vibrating membrane devices to deliver the drug. These studies determined that the eFlow® vibrating membrane technology delivers dornase alfa more rapidly and efficiently than jet nebulizers, and does not affect the physicochemical properties of the drug. These in vitro results demonstrate only the technical feasibility of using vibrating membrane devices to deliver dornase alfa. Clinical studies will be required before any conclusions can be made regarding clinical safety and efficacy of these drug-device combinations for cystic fibrosis. PMID:20533437

  12. Nonlinear dual-axis biodynamic response of the semi-supine human body during vertical whole-body vibration

    NASA Astrophysics Data System (ADS)

    Huang, Ya; Griffin, Michael J.

    2008-04-01

    Nonlinear biodynamic responses are evident in many studies of the apparent masses of sitting and standing subjects in static postures that require muscle activity for postural control. In the present study, 12 male subjects adopted a relaxed semi-supine posture assumed to involve less muscle activity than during static sitting and standing. The supine subjects were exposed to two types of vertical vibration (in the x-axis of the semi-supine body): (i) continuous random vibration (0.25-20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75, and 1.0 m s -2 rms); (ii) intermittent random vibration (0.25-20 Hz) alternately at 0.25 and 1.0 m s -2 rms. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 10.35 to 7.32 Hz as the vibration magnitude increased from 0.125 to 1.0 m s -2 rms. This nonlinear response was apparent in both the vertical ( x-axis) apparent mass and in the horizontal ( z-axis) cross-axis apparent mass. As the vibration magnitude increased from 0.25 to 1.0 m s -2 rms, the median resonance frequency of the apparent mass with intermittent random vibration decreased from 9.28 to 8.06 Hz whereas, over the same range of magnitudes with continuous random vibration, the resonance frequency decreased from 9.62 to 7.81 Hz. The median change in the resonance frequency (between 0.25 and 1.0 m s -2 rms) was 1.37 Hz with the intermittent random vibration and 1.71 with the continuous random vibration. With the intermittent vibration, the resonance frequency was higher at the high magnitude and lower at the low magnitude than with continuous vibration of the same magnitudes. The response was typical of thixotropy that may be a primary cause of the nonlinear biodynamic responses to whole-body vibration.

  13. Vibration characteristics in a smart bridge model using shape-memory alloy fiber reinforced composite

    Microsoft Academic Search

    A. Shimamoto; H. Zhao; H. Abe

    2005-01-01

    A smart bridge model was proposed for active control on strength and vibration by changing material properties of shape memory alloy embedded in the bridge structure using TiNi\\/acrylic composite. A systemic experimental study was carried out to investigate the self-strengthening effect by shape recovery of pre-strained TiNi wires as well as vibration control by stiffness changing with direct electric heating

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  15. Nonlinear dual-axis biodynamic response of the semi-supine human body during longitudinal horizontal whole-body vibration

    NASA Astrophysics Data System (ADS)

    Huang, Ya; Griffin, Michael J.

    2008-04-01

    The resonance frequencies in frequency response functions of the human body (e.g. apparent mass and transmissibility) decrease with increasing vibration magnitude. This nonlinear biodynamic response is found with various sitting and standing postures requiring postural control. The present study measured the apparent mass of the body in a relaxed semi-supine posture with two types of longitudinal horizontal vibration (in the z-axis of the semi-supine body): (i) continuous random excitation (0.25-20 Hz) at five magnitudes (0.125, 0.25, 0.5, 0.75 and 1.0 ms -2 rms); (ii) intermittent random excitation (0.25-20 Hz) alternately at 0.25 and 1.0 ms -2 rms. With continuous random vibration, the dominant primary resonance frequency in the median normalised apparent mass decreased from 3.7 to 2.4 Hz as the vibration magnitude increased from 0.125 to 1.0 ms -2 rms. A nonlinear response was apparent in both the horizontal ( z-axis) apparent mass and the vertical ( x-axis) cross-axis apparent mass. With intermittent random vibration, as the vibration magnitude increased from 0.25 to 1.0 ms -2 rms, the median resonance frequency of the apparent mass decreased from 3.2 to 2.5 Hz whereas, with continuous random vibration over the same range of magnitudes, the resonance frequency decreased from 3.4 to 2.4 Hz. The median change in the resonance frequency (between 0.25 and 1.0 ms -2 rms) was 0.6 Hz with the intermittent random vibration and 0.9 Hz with the continuous random vibration. With intermittent vibration, the resonance frequency was higher at the high magnitude and lower at the low magnitude than with continuous vibration at the same magnitudes. The responses were consistent with passive thixotropy being a primary cause of nonlinear biodynamic responses to whole-body vibration, although reflex activity of the muscles may also have an influence.

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

    PubMed Central

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

    2014-01-01

    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

  17. The effect of vibration on postural response of Down syndrome individuals on the seesaw.

    PubMed

    Carvalho, Regiane Luz; Almeida, Gil Lúcio

    2009-01-01

    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 seesaws of different heights. The individuals with DS adopted a pattern of co-contraction and were not able to modulate the magnitude of postural response with the seesaw's height. The vibration affected neither the ability of individuals with DS to maintain balance nor the pattern of muscle contraction. On the other hand the control group changed the strategy with vibration, adopting one similar to that used by individuals with DS. Collectively, our findings suggest that proprioceptive information is essential for the motor control system to select the appropriate motor strategy of reciprocal activation among the agonist and antagonist to efficiently balance. Also, these findings suggest that a proprioceptive deficit could explain the atypical motor strategy observed in individuals with DS during balance on seesaw. PMID:19394195

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

    NASA Technical Reports Server (NTRS)

    Hunt, Ronald A.

    2011-01-01

    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.

  19. Effects of an elastic mass on frequency response characteristics of an ultra-thin piezoelectric micro-acoustic actuator.

    PubMed

    Kim, Hye Jin; Yang, Woo Seok; No, Kwangsoo

    2013-08-01

    This paper presents an optimized method to improve the sound quality of ultra-thin piezoelectric micro-acoustic actuators. To achieve flat and smooth frequency response characteristics of the piezoelectric acoustic actuators, we have proposed an elastic mass attached to the acoustic diaphragm. The effects of the elastic mass on frequency response characteristics of the piezoelectric acoustic actuator were investigated by finite element analysis simulation and laser scanning vibrometer measurement. Based on the modal and vibrational characteristics, it was found that the fabricated piezoelectric acoustic actuator has a significant dip of 1.32 kHz and peak of 2.24 kHz, which correspond respectively to the (1,3) and (3,1) resonant modes of the acoustic diaphragm. However, by attaching an elastic mass to the acoustic diaphragm with a shape similar to the (3,1) mode, the resonant frequencies corresponding to the (1,3) and (3,1) modes shifted to higher frequencies and the vibrational displacements at each mode were dramatically reduced by about 40%. As a result, the dip at (1,3) mode was greatly improved by 13 dB and total harmonic distortion was dramatically reduced from 80.83% to 8.71%. This paper shows that the optimized elastic mass can allow flat and smooth frequency response characteristics by improving the significant peak and dip. PMID:25004529

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    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.

  1. Analytical and experimental comparisons of electromechanical vibration response of a piezoelectric bimorph beam for power harvesting

    NASA Astrophysics Data System (ADS)

    Lumentut, M. F.; Howard, I. M.

    2013-03-01

    Power harvesters that extract energy from vibrating systems via piezoelectric transduction show strong potential for powering smart wireless sensor devices in applications of health condition monitoring of rotating machinery and structures. This paper presents an analytical method for modelling an electromechanical piezoelectric bimorph beam with tip mass under two input base transverse and longitudinal excitations. The Euler-Bernoulli beam equations were used to model the piezoelectric bimorph beam. The polarity-electric field of the piezoelectric element is excited by the strain field caused by base input excitation, resulting in electrical charge. The governing electromechanical dynamic equations were derived analytically using the weak form of the Hamiltonian principle to obtain the constitutive equations. Three constitutive electromechanical dynamic equations based on independent coefficients of virtual displacement vectors were formulated and then further modelled using the normalised Ritz eigenfunction series. The electromechanical formulations include both the series and parallel connections of the piezoelectric bimorph. The multi-mode frequency response functions (FRFs) under varying electrical load resistance were formulated using Laplace transformation for the multi-input mechanical vibrations to provide the multi-output dynamic displacement, velocity, voltage, current and power. The experimental and theoretical validations reduced for the single mode system were shown to provide reasonable predictions. The model results from polar base excitation for off-axis input motions were validated with experimental results showing the change to the electrical power frequency response amplitude as a function of excitation angle, with relevance for practical implementation.

  2. Vibration characteristics of functionally graded cylindrical shells under various boundary conditions

    Microsoft Academic Search

    S. C. Pradhan; C. T. Loy; K. Y. Lam; J. N. Reddy

    2000-01-01

    In the recent years, functionally gradient materials (FGMs) have gained considerable attention in the high temperature environment applications. In the present work, study of the vibration of a functionally graded cylindrical shell made up of stainless steel and zirconia is presented. Material properties are graded in the thickness direction of the shell according to volume fraction power law distribution. Effects

  3. A Study of the Temperature Characteristics of Vibration Mode Axes for Vibratory Cylinder Gyroscopes

    PubMed Central

    Wu, Yulie; Xi, Xiang; Tao, Yi; Wu, Xiaomei; Wu, Xuezhong

    2011-01-01

    The zero bias stability, which is an important performance parameter for vibratory cylinder gyroscopes, is high sensitive to temperature change. It is considered that the varying temperature makes the vibration mode axes unstable, which has significant influence on the zero bias stability. This paper will investigate this problem in detail. First, the relationships between the angular positions of vibration mode axes and the zero bias are analyzed. Secondly, the thermal-modal model of the cylinder resonator with several defects such as mass imbalance, frequency split (FS), and geometry errors are developed by ANSYS. Simulation results show that with the increase of temperature, angular positions of the vibration mode axes obviously change, which leads to a dramatic zero bias drift. Finally, several major influence factors on the angular position stability of vibration mode axes, including frequency split, geometry errors, thermal elastic modulus coefficient (TEMC) and thermal expansion coefficient (TEC) are analyzed in detail. Simulation results in this paper will be helpful for deep understanding of the drift principle of zero bias induced by temperature for vibratory cylinder gyroscopes and also be helpful for further temperature compensation or control. PMID:22164038

  4. Characteristics of the vibrating-mesh minimum ignition energy testing apparatus for dust clouds

    Microsoft Academic Search

    K. S. Choi; M. Yamaguma; T. Kodama; J. H. Joung; M. Takeuchi

    2001-01-01

    A novel apparatus for testing the minimum ignition energies of flammable dusts is introduced. Unlike the conventional apparatus (the Hartmann tube), this new apparatus employs a vibrating mesh to produce a dust cloud. Using three kinds of powders, namely lycopodium, anthraquinone and polyacrylonitrile, which are designated as the samples for calibration by the International Electrotechnical Commission (IEC, 1994) standards, fundamental

  5. [Identification of the characteristic vibrations for 16 PAHs based on Raman spectrum].

    PubMed

    Zeng, Ya-Ling; Jiang, Long; Cai, Xiao-Yu; Li, Yu

    2014-11-01

    In the present paper, by means of density functional theory in B3LYP/6-311++G(d, p) method, 16 kinds of pollutants, i. e. polycyclic aromatic hydrocarbons (PAHs): naphthalene (Nap), acenaphthylene (AcPy), acenaphthene (Acp), fluorene (Flu), phenanthrene (PA), anthracene (Ant), fluoranthene (Fl), pyrene (Pyr), benzo [a] anthracene (BaA), fused two naphthalene (CHR), benzo [b] fluoranthene (BbF), benzo [k] fluoranthene (BkF), benzo [a] pyrene (BaP), dibenzo (a, h) anthracene (DahA), dibenzo [g, h, i] pyrene (BghiP) and indene benzene (1, 2, 3-cd) pyrene (IcdP) among the U. S. EPA priority pollutants were selected, whose structures were optimized and Raman vibrational frequencies and depolarization were calculated. The structure, Raman vibrational frequencies and depolarization were basis of identification of PAHs. Studies have shown that Raman vibrations of 16 PAHs are mainly distributed in three frequency regions: 200-1 000 cm(-1) (fingerprint region), 1 000-1 700 cm(-1) and 3 000-3 200 cm(-1) (group frequency region), corresponding vibrations were assigned to ring deformation (ring def), C-C stretching (CCStr), C-H wiggle (CHw) and of these two patterns (CCStrCCw), and C-H stretching (CHStr). Further analysis showed that in fingerprint region the depolarization of 16 PAHs was reduced with the symmetry of benzene deformation vibration enhanced. At the point of minimum depolarization, symmetry and Raman peak of benzene ring breathing vibration were found strongest. At the minimum differential wave number the strongest peak in fingerprint region was distinguishable by micro-Raman spectroscopy. Therefore, 16 PAHs can be individually identified by depolarization and the strongest peak in fringerprint region. Vibration frequencies and peak intensity distribution of alkanes (Akn), olefin (Oe), alkyne (Aye), alcohols and phenols (Aap), aliphatic ether (Ape), arylalkyl ether (Aae), aldehydes (Ahd), ketones (Ktn), carboxylic acid (Cba), esters (Etr), amines (Aie), nitriles (Nte), amides (Aid), acid anhydride (Ahr), aromatic hydrocarbons (Ahc) were not completely consistent with each other, and interference can be discharged by the differences of frequency and peak intensity distribution. PMID:25752046

  6. Analysis of Nonlinear Characteristics and Transient Response of IMPATT Amplifiers

    Microsoft Academic Search

    H. J. Kuno

    1973-01-01

    Nonlinear characteristics, large-signal effects, and transient response of IMPATT amplifiers are analyzed leading to clear understanding of various nonlinear and large-signal phenomena which are often observed experimentally on IMPATT diodes operated as stable (linear) amplifiers or injection-locked oscillators. Effects of bandwidth on transient response of the IMPATT amplifiers as applied to phase-modulated signals and amplitude-modulated signals are investigated in detail.

  7. Estimation of dynamic characteristics of a medium height office building with passive dampers considering vertical seismic response

    NASA Astrophysics Data System (ADS)

    Ishikawa, Misaki; Mita, Akira

    2011-04-01

    In this paper, dynamic characteristics of a medium-height office building with passive dampers is investigated. The building considered here is equipped with two kinds of passive dampers, viscous vibration control walls and low yield point steel-based buckling resistant braces. Eleven accelerometers are installed on basement, 1st, 5th, 10th and 14th floor. Two displacement meters for measuring the response of dampers are installed. To know the real performance of the building, we consider not only horizontal components but also vertical components. Dynamic characteristics of the building under several earthquakes are analyzed using multi-input and multi-output models for system identification. Using acceleration responses of multiple observation points, dynamic characteristics are estimated more precisely. The estimation errors of modal parameters are obtained simultaneously. Applying the method, it is indicated that vertical input has a significant influence on translational components.

  8. Hand-arm vibration syndrome and dose-response relation for vibration induced white finger among quarry drillers and stonecarvers. Italian Study Group on Physical Hazards in the Stone Industry.

    PubMed Central

    Bovenzi, M

    1994-01-01

    OBJECTIVES--To investigate the occurrence of disorders associated with the hand arm vibration syndrome in a large population of stone workers in Italy. The dose-response relation for vibration induced white finger (VWF) was also studied. METHODS--The study population consisted of 570 quarry drillers and stonecarvers exposed to vibration and 258 control stone workers who performed only manual activity. Each subject was interviewed with health and workplace assessment questionnaires. Sensorineural and VWF disorders were staged according to the Stockholm workshop scales. Vibration was measured on a representative sample of percussive and rotary tools. The 8 h energy equivalent frequency weighted acceleration (A (8)) and lifetime vibration doses were calculated for each of the exposed stone workers. RESULTS--Sensorineural and musculoskeletal symptoms occurred more frequently in the workers exposed to vibration than in the controls, but trend statistics did not show a linear exposure-response relation for these disorders. The prevalence of VWF was found to be 30.2% in the entire group exposed to vibration. Raynaud's phenomenon was discovered in 4.3% of the controls. VWF was strongly associated with exposure to vibration and a monotonic dose-response relation was found. According to the exposure data of this study, the expected percentage of stone workers affected with VWF tends to increase roughly in proportion to the square root of A(8) (for a particular exposure period) or in proportion to the square root of the duration of exposure (for a constant magnitude of vibration). CONCLUSION--Even although limited to a specific work situation, the dose-response relation for VWF estimated in this study suggests a time dependency such that halving the years of exposure allows a doubling of the energy equivalent vibration. According to these findings, the vibration exposure levels currently under discussion within the European Community seem to represent reasonable exposure limits for the protection of workers against the harmful effects of hand transmitted vibration. PMID:7951792

  9. Vibrational response prediction of a pneumatic tyre using an orthotropic two-plate wave model

    NASA Astrophysics Data System (ADS)

    Muggleton, J. M.; Mace, B. R.; Brennan, M. J.

    2003-07-01

    A wave model to predict the vibrational response of a pneumatic tyre subject to line force excitation is presented. The tread and sidewalls are each modelled as thin, flat orthotropic plates with in-plane tension, which are joined together by a translational stiffness, and to a rigid rim. The dynamic response of the tyre to harmonic excitation is decomposed into spatial harmonics around the circumference, and waves in the meridional direction. At low frequencies (<100 Hz), the response is stiffness-like, and is controlled by the sidewall properties and tension effects resulting from the tyre pressure. In the mid-frequency range (100-500 Hz), a resonant response is observed, associated with modes both across and around the tyre. At high frequencies (>500 Hz), the response tends towards that of an infinite orthotropic plate. Experiments have been conducted on an inflated tyre fitted to a wheel rim to confirm the theoretical findings. The results show reasonable agreement with the predictions, the model accurately reflecting the phenomenological behaviour.

  10. The Tendency to Omit Items: Another Deviant Response Characteristic.

    ERIC Educational Resources Information Center

    Hattie, John

    1983-01-01

    It is argued that the tendency to omit items is a deviant response characteristic. Three studies using a self-actualization measure are outlined. Persons who omitted items did so because of fatigue, confusion with some items, unpreparedness to disclose information, and/or because they may not trust the researcher with certain information.…

  11. Frequency Domain Controller Design 9.2 Frequency Response Characteristics

    E-print Network

    Gajic, Zoran

    Frequency Domain Controller Design 9.2 Frequency Response Characteristics The frequency transfer functions are defined for sinusoidal inputs having all possible frequencies . They are obtained from (9.1) by simply setting , that is (9.1) Typical diagrams for the magnitude and phase of the open-loop frequency

  12. Dynamic Characteristics of Retinal Ganglion Cell Responses in Goldfish

    PubMed Central

    Schellart, Nico A. M.; Spekreijse, Henk

    1972-01-01

    A cross-correlation technique has been applied to quantify the dependence of the dynamic characteristics of retinal ganglion cell responses in goldfish on intensity, wavelength, spatial configuration, and spot size. Both theoretical and experimental evidence justify the use of the cross-correlation procedure which allows the completion of rather extensive measurements in a relatively short time. The findings indicate the following. (a) The shape of the amplitude characteristics depends on the energy per unit of time (power) falling within the center of a receptive field rather than on the intensity of the stimulus spot. For spot diameters of up to 1 mm, identical amplitude characteristics can be obtained by interchanging area and intensity. Therefore the receptor processes do not contribute to the change in the amplitude characteristics as a function of the power of the stimulus light. (b) For high frequencies the amplitude characteristics obtained as a function of power join together in a common envelope if plotted on an absolute sensitivity scale. For spontaneous ganglion cells this envelope holds over a range of three log units and the shape is identical for central and peripheral processes. (c) The amplitude characteristics of the central and peripheral processes converging to a ganglion cell are identical, irrespective of the sign (on or off) and the spectral coding of the response. Therefore we have no evidence for interneurons in the goldfish retina unique to the periphery of the receptive field. PMID:5007262

  13. On the analytic representation of the correlation function of linear random vibration systems

    E-print Network

    On the analytic representation of the correlation function of linear random vibration systems J characteristics of the response of discrete vibration systems with a random external excitation. The excitation Mathematical modeling of real­world vibration systems (e. g. vehicles moving on a rough guideway, rotating

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

    PubMed

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

    2014-08-14

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

  15. Experimental-numerical investigation of the dynamic stability of flexural-torsional vibrations of compressor blades under conditions of attached and separated flow. Part 2. Cross aerodynamic characteristics

    Microsoft Academic Search

    A. L. Stel’makh; A. P. Zinkovskii; Ya. A. Stel’makh

    2009-01-01

    We consider the results of investigation of cross aerodynamic characteristics of compressor blades and their dynamic stability\\u000a under flexural-torsional vibrations for the cases of attached and separated flows in broad ranges of variations of the phase\\u000a shift, the ratio of amplitudes of the translational and angular components of displacements, the angle of attack, the reduced\\u000a frequency of vibrations, and the

  16. Human vibration characteristic and experiment research on man-machine system in dynamic environment

    Microsoft Academic Search

    Xu Linan; E. Zhang; Liu Mingli; Shao Xiaochun; Zhang Fan

    2008-01-01

    According to the design and analysis needs of man-machine interface in mechanical system in dynamic environment, a 4-DOF vertical vibration model of the human upper body of man-machine system is set up based on multi-body dynamics. The kinetic parameters of this model are obtained by the method of parameter identification and optimization theory (equivalent mass, equivalent stiffness and equivalent damping).

  17. Application of RTK-GPS Technology in Vibration Characteristics Test of High Pylon

    Microsoft Academic Search

    Hu Qunge; Xu Chang

    2009-01-01

    With the development of global positioning system (GPS) receiver technology for high recording rate, it allows reliable monitoring of engineering structures, such as bridges, towers and tall buildings. A structural monitoring system based on the technology of real-time kinematic GPS (RTK-GPS) is devised for the high pylon of a cable-stayed bridge. The vibration data are collected and processed by using

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

    Microsoft Academic Search

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

    2009-01-01

    Currently, there is a great interest in the study of shape memory alloy (SMA) composites, since SMA wires with a small diameter\\u000a have become commercially available. Many potential uses have been found for SMA composites in shape control, vibration control,\\u000a and for the realization of structures with improved damage tolerance. In this work, two types of SMA-hybridized composites\\u000a are presented

  19. A Comparison of Energy-Resolved Vibrational Activation/Dissociation Characteristics of Protonated and Sodiated High Mannose N-Glycopeptides

    NASA Astrophysics Data System (ADS)

    Aboufazeli, Forouzan; Kolli, Venkata; Dodds, Eric D.

    2015-04-01

    Fragmentation of glycopeptides in tandem mass spectrometry (MS/MS) plays a pivotal role in site-specific protein glycosylation profiling by allowing specific oligosaccharide compositions and connectivities to be associated with specific loci on the corresponding protein. Although MS/MS analysis of glycopeptides has been successfully performed using a number of distinct ion dissociation methods, relatively little is known regarding the fragmentation characteristics of glycopeptide ions with various charge carriers. In this study, energy-resolved vibrational activation/dissociation was examined via collision-induced dissociation for a group of related high mannose tryptic glycopeptides as their doubly protonated, doubly sodiated, and hybrid protonated sodium adduct ions. The doubly protonated glycopeptide ions with various compositions were found to undergo fragmentation over a relatively low but wide range of collision energies compared with the doubly sodiated and hybrid charged ions, and were found to yield both glycan and peptide fragmentation depending on the applied collision energy. By contrast, the various doubly sodiated glycopeptides were found to dissociate over a significantly higher but narrow range of collision energies, and exhibited only glycan cleavages. Interestingly, the hybrid protonated sodium adduct ions were consistently the most stable of the precursor ions studied, and provided fragmentation information spanning both the glycan and the peptide moieties. Taken together, these findings illustrate the influence of charge carrier over the energy-resolved vibrational activation/dissociation characteristics of glycopeptides, and serve to suggest potential strategies that exploit the analytically useful features uniquely afforded by specific charge carriers or combinations thereof.

  20. Neural basis of new clinical vestibular tests: otolithic neural responses to sound and vibration.

    PubMed

    Curthoys, Ian S; Vulovic, Vedran; Burgess, Ann M; Manzari, Leonardo; Sokolic, Ljiljana; Pogson, Jacob; Robins, Mike; Mezey, Laura E; Goonetilleke, Samanthi; Cornell, Elaine D; MacDougall, Hamish G

    2014-05-01

    Extracellular single neuron recording and labelling studies of primary vestibular afferents in Scarpa's ganglion have shown that guinea-pig otolithic afferents with irregular resting discharge are preferentially activated by 500 Hz bone-conducted vibration (BCV) and many also by 500 Hz air-conducted sound (ACS) at low threshold and high sensitivity. Very few afferent neurons from any semicircular canal are activated by these stimuli and then only at high intensity. Tracing the origin of the activated neurons shows that these sensitive otolithic afferents originate mainly from a specialized region, the striola, of both the utricular and saccular maculae. This same 500 Hz BCV elicits vestibular-dependent eye movements in alert guinea-pigs and in healthy humans. These stimuli evoke myogenic potentials, vestibular-evoked myogenic potentials (VEMPs), which are used to test the function of the utricular and saccular maculae in human patients. Although utricular and saccular afferents can both be activated by BCV and ACS, the differential projection of utricular and saccular afferents to different muscle groups allows for differentiation of the function of these two sensory regions. The basic neural data support the conclusion that in human patients in response to brief 500 Hz BCV delivered to Fz (the midline of the forehead at the hairline), the cervical VEMP indicates predominantly saccular function and the ocular VEMP indicates predominantly utricular function. The neural, anatomical and behavioural evidence underpins clinical tests of otolith function in humans using sound and vibration. PMID:24754528

  1. Tensor decomposition techniques in the solution of vibrational coupled cluster response theory eigenvalue equations

    NASA Astrophysics Data System (ADS)

    Godtliebsen, Ian H.; Hansen, Mads Bøttger; Christiansen, Ove

    2015-01-01

    We show how the eigenvalue equations of vibrational coupled cluster response theory can be solved using a subspace projection method with Davidson update, where basis vectors are stacked tensors decomposed into canonical (CP, Candecomp/Parafac) form. In each update step, new vectors are first orthogonalized to old vectors, followed by a tensor decomposition to a prescribed threshold TCP. The algorithm can provide excitation energies and eigenvectors of similar accuracy as a full vector approach and with only a very modest increase in the number of vectors required for convergence. The algorithm is illustrated with sample calculations for formaldehyde, 1,2,5-thiadiazole, and water. Analysis of the formaldehyde and thiadiazole calculations illustrate a number of interesting features of the algorithm. For example, the tensor decomposition threshold is optimally put to rather loose values, such as TCP = 10-2. With such thresholds for the tensor decompositions, the original eigenvalue equations can still be solved accurately. It is thus possible to directly calculate vibrational wave functions in tensor decomposed format.

  2. Flexoelectric effect on the electroelastic responses and vibrational behaviors of a piezoelectric nanoplate

    NASA Astrophysics Data System (ADS)

    Zhang, Zhengrong; Yan, Zhi; Jiang, Liying

    2014-07-01

    Flexoelectricity, referring to the coupling between electric polarization and strain gradients, is a universal effect in all dielectrics and may become manifest at the nano-scale. The current work aims to investigate the flexoelectric effect on the electroelastic responses and the free vibrational behaviors of a piezoelectric nanoplate (PNP). Based on the conventional Kirchhoff plate theory and the extended linear piezoelectricity theory, the governing equation and the boundary conditions of a clamped PNP with the consideration of the static bulk flexoelectricity are derived. Ritz approximate solutions of the electroelastic fields and the resonant frequencies demonstrate the size-dependency of the flexoelectric effect, which is more prominent for thinner plates with smaller thickness as expected. Simulation results also indicate that the influence of the flexoelectricity upon the electroelastic fields of a bending PNP and the transverse vibration of the PNP is sensitive to the plate in-plane dimensions as well as the applied electric voltage. Moreover, it is suggested that the possible frequency tuning of a PNP resonator by adjusting applied electrical load warrants the consideration of the flexoelectricity. This study is claimed to provide a theoretical predicition on the trend of the flexoelectric effect upon the static and dynamic behaviors of a bending PNP, thus sheding light on understanding the underlying physics of electromechanical coupling at the nano-scale to some extent.

  3. Effect of supplemental tryptophan, vitamin E, and a herbal product on responses by pigs to vibration.

    PubMed

    Peeters, E; Driessen, B; Steegmans, R; Henot, D; Geers, R

    2004-08-01

    Economic losses related to increased stress during the transport of pigs are well documented. The effects of supplementing of tryptophan (Trp), vitamin E, or a herbal product via feed or drinking water were investigated in terms of effects on stress response in pigs during transport simulation. The study consisted of three analogous experiments. For the testing in each experiment, the pigs (23.5+/-3.2 kg) were allocated to one of two treatments, with and without supplementation of a product. The applied doses were Trp (5 g/L drinking water for 3 d), vitamin E (additional amount of 300 mg/kg feed for 21 d, as-fed basis), and Sedafit (2.5 g/L drinking water for 2 d). Sedafit is a commercial herbal product containing Valeriana officinalis L. and Passiflora incarnata L. as active components. In each experiment of the study, at least 47 pigs were involved, which were treated in groups of 3. The day before transport simulation, a Holter device was attached to the pigs to produce an electrocardiogram during the night (rest values), as well as during vibration in the transport simulator (1.2 Hz, 1 m/s2), where the behavior of the pigs (standing-sitting-lying) was also observed. Samples of saliva (taken before, during, and after [3x] vibration) and blood (taken before and after vibration) were analyzed for cortisol and intermediate metabolites (glucose, lactate, creatine kinase, and nonesterified fatty acids), respectively. Pigs supplemented with Trp tended to spend more time lying down during the second hour of vibration (P < 0.05). Vitamin E decreased the peak heart rate (P < 0.05), ventricular ectopic beats (P < 0.01), and ST elevation (P < 0.10). The supplementation of Sedafit resulted in smaller increases of the investigated heart variables (minimum heart rate, P < 0.05; ventricular ectopic beats, P < 0.05; ST elevation, P < 0.01) during and after stress evocation compared with the control group. None of the tested products influenced the intermediate metabolites; one possible explanation for this finding may be that peak values were reached before the time of bleeding. In conclusion, Trp had a positive behavioral effect in this experiment, and vitamin E and Sedafit mediated an increase in some heart variables, suggesting sedative and antianxiety effects. PMID:15318742

  4. A hybrid analytical model for the transverse vibration response of a micro-end mill

    NASA Astrophysics Data System (ADS)

    Mustapha, K. B.; Zhong, Z. W.

    2013-01-01

    As a result of its detrimental effect on tool life and product quality, vibration analyses are crucial if the full potential of micro-milling operation is to be attained. In this paper, a hybrid analytical model (HAM) developed for estimating the transverse response of a micro-end mill is presented. The HAM is a combination of discrete and distributed structural elements. The discrete elements account for the stiffness and damping coefficients of the machining system, while the distributed elements idealize the geometrical representation of the micro-end mill with a novel model of the micro-flute. A number of slot micro-end milling operations, carefully designed with the Taguchi method of design of experiments, are carried out to examine the accuracy of the HAM. The comparison of the response profile from the experiment and the developed model shows reasonably close similarity. The influence of the helix angle is found to be far greater on the response of the micro-end mill than the other geometric variables. By making use of the root mean square of the response, it is further observed that the representation of the micro-flute of the micro-end mill with a less accurate model deteriorates the prediction of the HAM.

  5. Method for determining the frequency-response characteristics of an element or system from the system transient output response to a known input function

    NASA Technical Reports Server (NTRS)

    Curfman, Howard J; Gardiner, Robert A

    1950-01-01

    A method is presented for the determination of the frequency-response characteristics of an element or system by utilizing the transient output response to a known but arbitrary input to the system. Since the application of special inputs, such as step functions or sinusoids, is often imperfect or impractical, a method for utilizing arbitrary inputs is desirable. Simple flight-test data may be reduced by this method to give the frequency response of an aircraft. Examples are given as determinations of aircraft frequency responses; however, the method can be applied to any type of dynamic system, such as automatic-control components, vibration-absorption equipment, and many types of instruments. The method requires that the arbitrary input function tend to a finite value after a finite time and that the system or element output be measured as a representative quantity having a static sensitivity. (author)

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

    SciTech Connect

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

    1995-07-06

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  8. Vibrational diagnostics of rotating machinery malfunctions

    NASA Astrophysics Data System (ADS)

    Muszynska, A.

    The diagnostics of rotating machinery malfunction, using vibration data in correlation with operational process data is outlined. The advantages of vibration monitoring systems as a part of preventive/predictive maintenance programs are emphasized. The basic principles of machinery diagnostics, and several specific malfunction symptoms supported by simple mathematical models are given. These malfunctions include unbalance, excessive radial preload, rotor to stator rubbing, fluid induced vibrations, loose stationary and rotating parts, coupled torsional/lateral vibration excitation, and rotor cracking. The experimental results and actual field data illustrate the rotor vibration responses for individual malfunctions. Application of synchronous and nonsynchronous perturbation testing used for identification of basic dynamic characteristics of machinery is presented. Future advancements in vibration monitoring and diagnostics of rotating machinery health are discussed. The basic instrumentation for machine monitoring is outlined.

  9. Psychological characteristics of successful SWAT\\/Tactical Response Team personnel

    Microsoft Academic Search

    John T. Super

    1995-01-01

    The purpose of the present study is to determine if the Wonderlic Personnel Test (WPT), California Psychological Inventory\\u000a (CPI), and Fundamental Interpersonal Relations Organization Behavior (FIRO-B) may be used to identify psychological characteristics\\u000a of successful SWAT\\/Tactical Response Team personnel. Thirty-four caucasian male subjects ranging in age between 26 to 45 years\\u000a served as subjects. Education levels ranged from high school

  10. Experimental research on the response characteristics of PLZT ceramics

    NASA Astrophysics Data System (ADS)

    Wang, X. J.; Huang, J. H.; Wang, J.

    2015-07-01

    PLZT ceramics have exhibited promising applications as wireless photo-driven micro actuators for their direct conversion from optical energy to mechanical energy. However, the slow response of photodeformation and the residual photovoltage and deformation prevent PLZT ceramics from being employed as micro actuators, especially in the high frequency dynamic field. The primary purposes of this article are to analyze the response characteristics of PLZT ceramics and look for some measures to improve the response performance of the photo-induced deformation. To this end, this study observed the slow response, the residual photovoltage and deformation through photostrictive static experiments. Some measures proposed to accelerate the response speed and eliminate the residual photovoltage and deformation in this paper were experimentally confirmed. From these experiments, the hysteresis phenomenon caused by temperature rising, the residual photovoltage and photo-induced deformation after turning off the ultraviolet light are considered to be the main reasons for the slow response of photo-induced deformation. The experimental results indicate that reducing the effect of temperature elevation, ground connection and using another PLZT ceramic to eliminate the residual photovoltage and deformation are proven ways to improve the response performance of photo-induced deformation. On that basis, two optical driving mechanisms were proposed.

  11. Free-vibration characteristics of a large split-blanket solar array in a 1-g field

    NASA Technical Reports Server (NTRS)

    Shaker, F. J.

    1976-01-01

    Two methods for studying the free vibration characteristics of a large split blanket solar array in both a 0-g and a 1-g cantilevered configuration are presented. The 0-g configuration corresponds to an in-orbit configuration of the array; the 1-g configuration is a typical ground test configuration. The first method applies the equations of continuum mechanics to determine the mode shapes and frequencies of the array; the second method uses the Rayleigh-Ritz approach. In the Rayleigh-Ritz method the array displacements are represented by string modes and cantilevered beam modes. The results of this investigation are summarized by a series of graphs illustrating the effects of various array parameters on the mode shapes and frequencies of the system. The results of the two methods are also compared in tabular form.

  12. Effect of axisymmetric vibration modes on sensitivity and di rectivity characteristics of piezoceramic sphere

    NASA Astrophysics Data System (ADS)

    Dyubchenko, M. Y.

    1985-03-01

    The performance of a piezoceramic hydrophone sphere with a hole for the electric cable is analyzed, taking into account the axisymmetric vibration modes and the resulting stresses produced by the cutout but assuming that a seal cover restores the spherical symmetry and does not alter the natural modes. The analysis is based on the corresponding equation of electromechanical state for such a sphere in the field of a plane sound wave. Conditions are established, in terms of constraints on the capacitor plates, for excitation of odd-order and even-order (including zero-order) axisymmetric modes. The sensitivity and the radiation pattern of such a hydrophone are calculated for a thin spherical shell with or without a passive zone. Minimization of the effect of axisymmetric modes results in a maximally isotropic nondirectional hydrophone, a passive zone with a smaller than 20 deg meridional angle being both adequate and feasible.

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

    NASA Astrophysics Data System (ADS)

    Velazquez, Antonio; Swartz, Raymond A.

    2011-04-01

    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.

  14. Density relaxation of a near-critical fluid in response to local heating and low frequency vibration in microgravity.

    PubMed

    Jounet, Arnaud

    2002-03-01

    The response of a confined near-critical fluid to local heating in the presence of vibration is studied by means of two-dimensional numerical simulations of the compressible and unsteady Navier-Stokes equations written for a van der Waals fluid. As in the experiments performed two years ago onboard the Mir orbital station, two different regimes of density distribution are observed. For sufficiently low frequency and high amplitude vibration, two thermal plumes develop from the heat source along the vibration axis. Otherwise (higher frequency and/or lower amplitude), density inhomogeneities caused by heating stay around the heat source. For this regime, the pair of vortices created in each half period absorbs the preceding one, while it is convected away for the double-plume regime. As time goes on, this process repeats, with a lateral extension of the low density region. At lower frequencies, instabilities appear in the flow, thus corroborating again microgravity experiments. PMID:11909321

  15. Energy harvesting and vibration control using piezoelectric elements and a nonlinear approach

    Microsoft Academic Search

    J. H. Qiu; H. L. Ji; H. Shen

    2009-01-01

    The piezoelectric materials, as the most widely used functional materials in smart structures, have many outstanding advantages for sensors and actuators, especially in vibration control and energy harvesting, because of their excellent mechanical-electrical coupling characteristics and frequency response characteristics. Semi-active vibration control based on state switching and pulse switching, have been receiving much attention over the past decade because of

  16. Frequency response functions of shape features from full-field vibration measurements using digital image correlation

    NASA Astrophysics Data System (ADS)

    Wang, Weizhuo; Mottershead, John E.; Siebert, Thorsten; Pipino, Andrea

    2012-04-01

    The availability of high speed digital cameras has enabled three-dimensional (3D) vibration measurement by stereography and digital image correlation (DIC). The 3D DIC technique provides non-contact full-field measurements on complex surfaces whereas conventional modal testing methods employ point-wise frequency response functions. It is proposed to identify the modal properties by utilising the domain-wise responses captured by a DIC system. This idea will be illustrated by a case study in the form a car bonnet of 3D irregular shape typical of many engineering structures. The full-field measured data are highly redundant, but the application of image processing using functional transformation enables the extraction of a small number of shape features without any significant loss of information from the raw DIC data. The complex bonnet surface on which the displacement responses are measured is essentially a 2-manifold. It is possible to apply surface parameterisation to 'flatten' the 3D surface to form a 2D planar domain. Well-developed image processing techniques are defined on planar domains and used to extract features from the displacement patterns on the surface of a specimen. An adaptive geometric moment descriptor (AGMD), defined on surface parametric space, is able to extract shape features from a series of full-field transient responses under random excitation. Results show the effectiveness of the AGMD and the obtained shape features are demonstrated to be succinct and efficient. Approximately 14 thousand data points of raw DIC measurement are represented by 20 shape feature terms at each time step. Shape-descriptor frequency response functions (SD-FRFs) of the response field and the loading field are derived in the shape feature space. It is seen that the SD-FRF has a similar format to the conventional receptance FRF. The usual modal identification procedure is applied to determine the natural frequencies, damping factors and eigen-shape-feature vectors from the SD-FRF. Natural frequencies and mode shapes from a finite element (FE) model are correlated with the experimental data using the cosine distance between the shape feature vectors with 20 terms. There are numerous benefits of using image decomposition to analyse 3D DIC measured data, including (1) representation of the raw measurement data with efficiency and succinctness; (2) determination of the FRF of any point on the specimen by the use of the full-field shape features; and (3) elimination of DIC measurement noise. Also, the SD-FRF is potentially ideal for cases of field excitation of structures.

  17. Direct quantum mechanical/molecular mechanical simulations of two-dimensional vibrational responses: N-methylacetamide in water

    NASA Astrophysics Data System (ADS)

    Jeon, Jonggu; Cho, Minhaeng

    2010-06-01

    Multidimensional infrared (IR) spectroscopy has emerged as a viable tool to study molecular structure and dynamics in condensed phases, and the third-order vibrational response function is the central quantity underlying various nonlinear IR spectroscopic techniques, such as pump-probe, photon echo and two-dimensional (2D) IR spectroscopy. In this paper, a new computational method is presented that calculates this nonlinear response function in the classical limit from a series of classical molecular dynamics (MD) simulations, employing a quantum mechanical/molecular mechanical (QM/MM) force field. The method relies on the stability matrix formalism where the dipole-dipole quantum mechanical commutators appearing in the exact quantum response function are replaced by the corresponding Poisson brackets. We present the formulation and computational algorithm of the method for both the classical and the QM/MM force fields and apply it to the 2D IR spectroscopy of carbon monoxide (CO) and N-methylacetamide (NMA), each solvated in a water cluster. The conventional classical force field with harmonic bond potentials is shown to be incapable of producing a reliable 2D IR signal because intramolecular vibrational anharmonicity, essential to the production of the nonlinear signal, is absent in such a model. The QM/MM force field, on the other hand, produces distinct 2D spectra for the NMA and CO systems with clear vertical splitting and cross peaks, reflecting the vibrational anharmonicities and the vibrational couplings between the underlying vibrational modes, respectively. In the NMA spectrum, the coupling between the amide I and II modes is also well reproduced. While attaining the converged spectrum is found to be challenging with this method, with an adequate amount of computing it can be straightforwardly applied to new systems containing multiple chromophores with little modeling effort, and therefore it would be useful in understanding the multimode 2D IR spectrum of complex molecular systems.

  18. Stationary levitation and vibration transmission characteristic in a superconducting seismic isolation device with a permanent magnet system and a copper plate

    NASA Astrophysics Data System (ADS)

    Sasaki, S.; Shimada, K.; Yagai, T.; Tsuda, M.; Hamajima, T.; Kawai, N.; Yasui, K.

    2010-11-01

    We have devised a magnetic levitation type superconducting seismic isolation device taking advantage of the specific characteristic of HTS bulk that the HTS bulk returns to its original position by restoring force against a horizontal displacement. The superconducting seismic isolation device is composed of HTS bulks and permanent magnets (PM rails). The PMs are fixed on an iron plate to realize the same polarities in the longitudinal direction and the different polarities in the transverse direction. The superconducting seismic isolation device can theoretically remove any horizontal vibrations completely. Therefore, the vibration transmissibility in the longitudinal direction of the PM rail becomes zero in theory. The zero vibration transmissibility and the stationary levitation, however, cannot be achieved in the real device because a uniform magnetic field distribution in the longitudinal direction of PM rail cannot be realized due to the individual difference of the PMs. Therefore, to achieve stationary levitation in the real device we adopted a PM-PM system that the different polarities are faced each other. The stationary levitation could be achieved by the magnetic interaction between the PMs in the PM-PM system, while the vibration transmitted to the seismic isolation object due to the magnetic interaction. We adopted a copper plate between the PMs to reduce the vibration transmissibility. The PM-PM system with the copper plate is very useful for realizing the stationary levitation and reducing the vibration transmissibility.

  19. The responses of auditory ventral-cord neurons of Locusta migratoria to vibration stimuli

    Microsoft Academic Search

    Andrej ?okl; Klaus Kalmring; Herbert Wittig

    1977-01-01

    Most of the auditory neurons in the ventral nerve cord ofLocusta migratoria carry information not only from the tympanal organs but also from the subgenual organs (vibration sensors). Six of the eight neuron types studied electrophysiologically respond to at least these two modalities. Artificial sounds (white noise and pure tones varying in frequency and intensity) and sinusoidal vibration (200 Hz

  20. Modelling the response of the spinal system to whole-body vibration and repeated shock

    Microsoft Academic Search

    Helmut Seidel; Michael J. Griffin

    2001-01-01

    Back problems are very common and contribute to discomfort and days off work. Some back disorders are attributed to inappropriate loading of the spine that can be combined with other influential factors such a body posture, whole-body vibration and shock. Many models have been developed to predict the forces in the spine associated with vibration and shock. However, the problem

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

    NASA Technical Reports Server (NTRS)

    Chattopadhyay, Aditi

    1996-01-01

    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.

  2. Stiffness and vibration characteristics of SMA\\/ER3 composites with shape memory alloy short fibers

    Microsoft Academic Search

    Qing-Qing Ni; Run-xin Zhang; Toshiaki Natsuki; Masaharu Iwamoto

    2007-01-01

    Shape memory alloys (SMAs) possess both sensing and actuating functions due to their shape memory effect, pseudo-elasticity, high damping capability and other remarkable characteristics. Combining the unique properties of SMAs with other materials can create intelligent or smart composites. In this paper, epoxy resin composites filled with Ni–Ti alloy short fibers were developed. Microstructure was observed using digital HF microscope.

  3. Preliminary Calibration Report of an Apparatus to Measure Vibration Characteristics of Low Frequency Disturbance Source Devices

    NASA Technical Reports Server (NTRS)

    Russell, James W.; Marshall, Robert A.; Finley, Tom D.; Lawrence, George F.

    1994-01-01

    This report presents a description of the test apparatus and the method of testing the low frequency disturbance source characteristics of small pumps, fans, camera motors, and recorders that are typical of those used in microgravity science facilities. The test apparatus will allow both force and acceleration spectra of these disturbance devices to be obtained from acceleration measurements over the frequency range from 2 to 300 Hz. Some preliminary calibration results are presented.

  4. Study of passenger subjective response to ideal and real-vehicle vibration environments

    NASA Technical Reports Server (NTRS)

    Kirby, R. H.; Mikulka, P. J.

    1975-01-01

    The stimulus received by subjects tested on the passenger ride quality apparatus (PRQA) is defined. Additional analyses on the data collected from field tests using buses, were conducted to assess the relation between subjective ratings of ride quality and vibrations measured on the buses, and to better define the vibration stimulus measured in the field. The relation of subjective evaluation of simulations of bus rides produced by the DRQA to subjective evaluations of the actual bus rides is discussed. The relative contribution of the seat and floor vibration to human comfort in a simulated aircraft ride environment is discussed along with the determination of equal comfort curves through magnitude estimation.

  5. Bending, Vibration and Buckling Response of Conventional and Modified Euler-Bernoulli and Timoshenko Beam Theories Accounting for the von Karman Geometric Nonlinearity 

    E-print Network

    Mahaffey, Patrick Brian

    2013-08-07

    Hamilton’s principle. These equations form the basis of investigations to determine certain microstructural length scales on the bending, vibration and buckling response of beams used in micro- and nano-devices. (2) Analytical solutions of the conventional...

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

    SciTech Connect

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

    1996-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    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).

  8. ANALYSIS OF BIODYNAMIC RESPONSES OF A SEATED BODY UNDER VERTICAL VIBRATION

    Microsoft Academic Search

    The objective assessment of occupational vibration exposure effects on the human body is largely determined from biodynamic functions obtained through measurement of the force-motion relationship at the body-seat interface. Such \\

  9. Three-dimensional biomechanical model for simulating the response of the human body to vibration stress

    Microsoft Academic Search

    M. Fritz

    1998-01-01

    Several investigations have revealed that long-term exposure to whole-body vibrations can induce low back pain. In analogy\\u000a to materials handling, the health risk can be assessed if the forces transmitted in the spine during vibration are known.\\u000a To estimate the forces a biomechanical model has been developed in which the human trunk, neck, head and arms are represented\\u000a by 16

  10. The influence of dynamic properties of ground soil on vibration characteristics of rigid body on sand ground

    Microsoft Academic Search

    Yoon-Sang Kim; Tae-Gyun Ha; Jae-Jin Choi; Choong-Ki Chung

    2007-01-01

    This study aims to investigate the influence of dynamic properties of the ground soil on vibration properties of a rigid body\\u000a placed on the sand ground surface to clarify the vibration behavior of a structure in terms of the interaction between the\\u000a structure and the ground. A series of cyclic triaxial tests and three types of model vibration tests were

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

    NASA Technical Reports Server (NTRS)

    Moyer, E. T., Jr.

    1984-01-01

    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.

  12. Fretting wear damage of heat exchanger tubes: A proposed damage criterion based on tube vibration response

    SciTech Connect

    Yetisir, M.; McKerrow, E.; Pettigrew, M.J. [Atomic Energy of Canada Ltd., Chalk River, Ontario (Canada). Chalk River Labs.

    1998-08-01

    A simple criterion is proposed to estimate fretting wear damage in heat exchanger tubes with clearance supports. The criterion is based on parameters such as vibration frequency, midspan vibration amplitude, span length, tube mass, and an empirical wear coefficient. It is generally accepted that fretting wear damage is proportional to a parameter called work rate. Work rate is a measure of the dynamic interaction between a vibrating tube and its supports. Due to the complexity of the impact-sliding behavior at the clearance supports, work rate calculations for heat exchanger tubes require specialized nonlinear finite element codes. These codes include contact models for various clearance support geometries. Such nonlinear finite element analyses are complex, expensive and time consuming. The proposed criterion uses the results of linear vibration analysis (i.e., vibration frequency and mid-span vibration amplitude due to turbulence) and does not require a nonlinear analysis. It can be used by nonspecialists for a quick evaluation of the expected work rate, and hence, the fretting wear damage of heat exchanger tubes. The proposed criterion was obtained from an extensive parametric study that was conducted using a nonlinear finite element program. It is shown that, by using the proposed work rate criteria, work rate can be estimated within a factor of two. This result, however, requires further testing with more complicated flow patterns.

  13. Efficient Nonparametric Approaches for Estimating the Operating Characteristics of Discrete Item Responses.

    ERIC Educational Resources Information Center

    Samejima, Fumiko

    1998-01-01

    Introduces and discusses the rationale and procedures of two nonparametric approaches to estimating the operating characteristic of a discrete item response, or the conditional probability, given the latent trait, that the examinee's response be that specific response. (SLD)

  14. DFT study of molecular geometries and vibrational characteristics of uracil and its thio-derivatives and their radical cations.

    PubMed

    Singh, R; Jaiswal, S; Kumar, M; Singh, P; Srivastav, G; Yadav, R A

    2010-01-01

    DFT calculations at the B3LYP/6-311++G** level have been carried out to study the vibrational characteristics of the neutral molecules, anionic and cationic radicals of uracil, 2-thiouracil and 4-thiouracil. In the U molecule, C=C bond loses its double bond character and magnitude of the C=C stretching frequency decreases significantly as a result of radicalization. Frequency for the in-plane deformation mode of C=O increases when a sulfur atom is substituted for the oxygen atom at the site C(2) in the uracil molecule but decreases when a sulfur atom is substituted for the oxygen atom at the site C(4). The magnitude of both the N-H stretching frequencies decreases in all the radical cations as compared to their neutral molecules. Radicalization leads to significant changes in the magnitudes and intensities corresponding to some of the normal modes for all the three cases. Removal of an electron leads to decrease in the electronic charge mainly from the sulfur atom in the case of 2-TU and 4-TU, whereas it is distributed over the sites N(1), C(5), O(8) and O(10) in case of the U molecule. PMID:19926335

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

    NASA Technical Reports Server (NTRS)

    Kahraman, Ahmet

    2002-01-01

    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.

  16. Characteristics of vibrational wave propagation and attenuation in submarine fluid-filled pipelines

    NASA Astrophysics Data System (ADS)

    Yan, Jin; Zhang, Juan

    2015-04-01

    As an important part of lifeline engineering in the development and utilization of marine resources, the submarine fluid-filled pipeline is a complex coupling system which is subjected to both internal and external flow fields. By utilizing Kennard's shell equations and combining with Helmholtz equations of flow field, the coupling equations of submarine fluid-filled pipeline for n=0 axisymmetrical wave motion are set up. Analytical expressions of wave speed are obtained for both s=1 and s=2 waves, which correspond to a fluid-dominated wave and an axial shell wave, respectively. The numerical results for wave speed and wave attenuation are obtained and discussed subsequently. It shows that the frequency depends on phase velocity, and the attenuation of this mode depends strongly on material parameters of the pipe and the internal and the external fluid fields. The characteristics of PVC pipe are studied for a comparison. The effects of shell thickness/radius ratio and density of the contained fluid on the model are also discussed. The study provides a theoretical basis and helps to accurately predict the situation of submarine pipelines, which also has practical application prospect in the field of pipeline leakage detection.

  17. Unstable vibration of roller mills

    Microsoft Academic Search

    K. Fujita; T. Saito

    2006-01-01

    The purpose of this study is to reveal the mechanism of unstable vibration occurring in the grinding operation of roller mills and to show the design guidelines for reducing the vibration. To study the basic cause of the unstable vibration, we first investigated the dynamic characteristics of the mill vibration in its stable state and its unstable state, using a

  18. Random vibration of mechanical and structural systems

    Microsoft Academic Search

    T. T. Soong; Mircea Grigoriu

    1993-01-01

    This book addresses random vibration of mechanical and structural systems commonly encountered in aerospace, mechanical, and civil engineering. Techniques are examined for determining probabilistic characteristics of the response of dynamic systems subjected to random loads or inputs and for calculating probabilities related to system performance or reliability. Emphasis is given to applications.

  19. Influence of vibration amplitude on laminar flow over a plate vibrating at low Strouhal number

    SciTech Connect

    Venkat, N.K. (Spaulding Environmental Associates, Inc., Wakefield, RI (United States)); Spaulding, M. (Univ. of Rhode Island, Kingston, RI (United States). Dept. of Ocean Engineering)

    1993-09-01

    The spectral and hydrodynamic response of laminar flow over a flat plate with a vibrating section forced in sinusoidal motion with a dimensionless amplitude ratio, H[sub 0] (vibration amplitude divided by plate length) varying in the range 0.0 < H[sub 0] < 0.1 is analyzed using numerical simulations. The Reynolds number, Re, based on the length of the vibrating plate, is fixed at 1,000. The flow is simulated for Strouhal number, St, = 0.25 (low frequency). The spectral characteristics are obtained by performing Fast Fourier Transform (FFT) on the pressure coefficient time series data. The hydrodynamic analysis is performed by plotting stream function contour plot in the vicinity of the vibrating section for one vibration cycle. The model predicted results show that the friction and pressure coefficients over the vibrating body vary with vibration amplitude. For low amplitude ratios, the interaction of the external flow with the vibrating section is linear and there is little up or downstream influence. For high H[sub 0], there is considerable downstream influence of the disturbance. Nonlinear energy transfer, as evidenced by the existence of a significant first harmonic in the pressure wave, takes place between the vibrating plate and the flow field. Energy transfer to the higher harmonics is less significant.

  20. Enhancement in the dynamic response of a viscoelastic fluid flowing through a longitudinally vibrating tube

    E-print Network

    Beresnev, Igor

    vibrating tube David Tsiklauri* and Igor Beresnev Department of Geological and Atmospheric Sciences, Iowa of a Maxwell fluid in a tube, which oscillates longitudinally and is subject to an oscillatory pressure theory of the flow of Maxwell fluid through a longitudinally oscillating cylindrical tube

  1. The forced vibrational response of a rectangular parallelepiped with rigid-lubricated boundaries

    Microsoft Academic Search

    E. V. K. Hill; D. M. Egle

    1982-01-01

    The Green function for a rectangular parallelepiped with rigid-lubricated boundaries is developed by a normal mode approach, the free vibration solutions being used. Explicit solutions are presented for a concentrated impulse, which serves as a model for an acoustic emission stress wave, and for a concentrated step force. Numerical results for short times show good agreement with the infinite space

  2. Structural-dynamic-response characteristics of Darrieus vertical-axis wind turbines

    SciTech Connect

    Sullivan, W.N.

    1981-01-01

    Operational experience at Sandia National Laboratories (SNL) with Darrieus-type vertical axis wind turbines (VAWTs) has indicated that a variety of dynamic issues can affect structural performance of the system. The observation and analysis of structural dynamic responses in the VAWT have been divided among three major aspects of the system; namely rotor vibrations, torsional response of the drive train, and transverse vibrations of the cables. This division is not arbitrary, but is rather because the response of these subsystems can be accurately decoupled from each other in most circumstances. This paper will present only a brief summary of the efforts now underway at SNL in the area of structural dynamics. The emphasis will be on discussing the status of our analytical tools, the quantity and quality of existing experimental confirmation data, and the implications structural dynamic issues have on rotor design.

  3. Stress response effects on growth, carcass characteristics, and tenderness in Bonsmara-influenced steers 

    E-print Network

    Falkenberg, Shollie Marie

    2006-08-16

    Half-blood Bonsmara steers were evaluated for temperament during stressful situations to discover the relationships between behavioral stress responses, growth, carcass characteristics and tenderness. Two experiments were ...

  4. On the use of non-linear vibrations and the anti-resonances of Higher-Order Frequency Response Functions for crack detection

    E-print Network

    Paris-Sud XI, Université de

    On the use of non-linear vibrations and the anti-resonances of Higher-Order Frequency Response-resonances in Higher-Order Frequency Response Functions can provide useful information on the presence of cracks of the proposed methodology is illustrated through numerical examples for a pipeline beam including a breathing

  5. Immune Response Characteristics in Women with Chlamydial Genital Tract Infection

    Microsoft Academic Search

    Dean S. Cunningham

    1995-01-01

    Immune responses in women with chlamydial genital tract infection who achieved a bacteriologic cure were prospectively compared to those women who had an incomplete clinical response. Local anti-chlamydia IgA antibody responses were significantly diminished in the outpatient treatment group who had an incomplete response, while circulating IgG responses did not differ significantly between groups. This is in contrast to both

  6. Neural network approach to damage detection in a building from ambient vibration measurements

    Microsoft Academic Search

    Mitsuru Nakamura; Sami F. Masri; A. G. Chassiakos; T. K. Caughey

    1998-01-01

    A neural network-based approach is presented for the detection of changes in the characteristics of structure- unknown systems. The approach relies on the use of vibration measurements from a `healthy' system to train a neural network for identification purposes. Subsequently, the trained network is fed comparable vibration measurements from the same structure under different episodes of response in order to

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

    Microsoft Academic Search

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

    1995-01-01

    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

  8. The forced vibrational response of a rectangular parallelepiped with rigid-lubricated boundaries

    NASA Astrophysics Data System (ADS)

    Hill, E. v. K.; Egle, D. M.

    1982-01-01

    The Green function for a rectangular parallelepiped with rigid-lubricated boundaries is developed by a normal mode approach, the free vibration solutions being used. Explicit solutions are presented for a concentrated impulse, which serves as a model for an acoustic emission stress wave, and for a concentrated step force. Numerical results for short times show good agreement with the infinite space solution. Analogous solutions are developed for the inverse boundary conditions.

  9. Low-frequency vibrations associated with fan discharge grille system

    SciTech Connect

    Teng, C.; Shearer, K.W.; Sullivan, L.J.; Burns, L.D. [Carrier Corp., Indianapolis, IN (United States)

    1998-10-01

    This paper discusses the vibration characteristics of a fan discharge grille system, used in residential air-conditioning units, which has annoying rattles and visible vibrations. Three main sources associated with these rattles and vibrations were identified. These sources were the three common driving forces in the air-conditioning systems plus the excessive system responses to them. The primary causes for the annoying rattles were the torsional vibration modes of the grille driven by the fan motor torque pulsation at two times line frequency. Different experimental techniques--operation test, sweep test, impact test, and torsional shaker test--were used in the investigation. The driving forces could be identified by correlating vibration peaks in the operation and sweep tests with the fan rotating speed, blade passage frequency, and line frequency. The impact test and torsional shaker test without the fan installed could be used to clarify the nature of the system responses.

  10. Secondary Periodicity in the Structural and Vibrational Characteristics of 3,3-DIMETHYLCYCLOPROPENES - and Monosubstituted by -X{(CH_3)}_3 (x = C, Si, Ge, Sn, Pb)

    NASA Astrophysics Data System (ADS)

    Panchenko, Yu. N.; Abramenkov, A. V.; de Maré, G. R.

    2009-06-01

    The regularities of changes in the structural parameters and vibrational wavenumbers have been traced for certain moieties of the title compounds. The optimized geometrical parameters and the force fields of disubstituted 3,3-dimethylcyclopropenes and monosubstituted 3,3-dimethylcyclopropenes were determined at the HF/3-21G* and DDAll levels, respectively. The choice of these theoretical levels was brought about by peculiarities of GAUSSIAN 03 suite of programs for Sn and Pb atoms. The theoretical vibrational wavenumbers were calculated from the corresponding scaled force fields. The regularities obtained in the form of the zigzag lines are analogous to regularities that are characteristic to the atoms of the 14 (IVA) group of the Mendeleyev Periodic Table. This is known as the secondary periodicity phenomenon. Yu. N. Panchenko, G. R. De Maré, A. V. Abramenkov, and A. de Meijere, Spectrochim. Acta 65A, 575 (2006). G. R. De Maré, Yu. N. Panchenko, and A. V. Abramenkov, Spectrochim. Acta 67A, 1094 (2007).

  11. Dynamic Responses and Vibration Control of the Transmission Tower-Line System: A State-of-the-Art Review

    PubMed Central

    Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping

    2014-01-01

    This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers. PMID:25105161

  12. Ultrasonic vibration-assisted pelleting of wheat straw: a predictive model for energy consumption using response surface methodology.

    PubMed

    Song, Xiaoxu; Zhang, Meng; Pei, Z J; Wang, Donghai

    2014-01-01

    Cellulosic biomass can be used as a feedstock for biofuel manufacturing. Pelleting of cellulosic biomass can increase its bulk density and thus improve its storability and reduce the feedstock transportation costs. Ultrasonic vibration-assisted (UV-A) pelleting can produce biomass pellets whose density is comparable to that processed by traditional pelleting methods (e.g. extruding, briquetting, and rolling). This study applied response surface methodology to the development of a predictive model for the energy consumption in UV-A pelleting of wheat straw. Effects of pelleting pressure, ultrasonic power, sieve size, and pellet weight were investigated. This study also optimized the process parameters to minimize the energy consumption in UV-A pelleting using response surface methodology. Optimal conditions to minimize the energy consumption were the following: ultrasonic power at 20%, sieve size at 4 mm, and pellet weight at 1g, and the minimum energy consumption was 2.54 Wh. PMID:23859359

  13. Dynamic responses and vibration control of the transmission tower-line system: a state-of-the-art review.

    PubMed

    Chen, Bo; Guo, Wei-hua; Li, Peng-yun; Xie, Wen-ping

    2014-01-01

    This paper presented an overview on the dynamic analysis and control of the transmission tower-line system in the past forty years. The challenges and future developing trends in the dynamic analysis and mitigation of the transmission tower-line system under dynamic excitations are also put forward. It also reviews the analytical models and approaches of the transmission tower, transmission lines, and transmission tower-line systems, respectively, which contain the theoretical model, finite element (FE) model and the equivalent model; shows the advances in wind responses of the transmission tower-line system, which contains the dynamic effects under common wind loading, tornado, downburst, and typhoon; and discusses the dynamic responses under earthquake and ice loads, respectively. The vibration control of the transmission tower-line system is also reviewed, which includes the magnetorheological dampers, friction dampers, tuned mass dampers, and pounding tuned mass dampers. PMID:25105161

  14. Characteristics of cervico-ocular responses in the chameleon.

    PubMed

    Gioanni, H; Sansonetti, A; Bennis, M

    1997-01-01

    The cervico-ocular reflex (COR) was investigated in the chameleon. Two kinds of responses were observed by oscillating the body (sine-wave stimuli) in the fixed-head animal: a "smooth response" of very low gain (around 0.08) and a saccadic response composed of 1-12 saccades per cycle of stimulation (depending on the stimulation frequency). Both responses were elicited in the compensatory direction (same direction as the stimulation) and exhibited a frequency dependence with low-pass properties. The saccadic response was especially developed and displayed a higher gain (up to 0.4) than the smooth response. In darkness, the saccades were triggered near the zero point (head-body alignment), whereas in the presence of a fixed visual surround they were elicited more regularly throughout the stimulation cycle. The amplitude of saccades was increased in the light. Consequently, the gain and the phase lag of the saccadic response were enhanced by the visual input. No visuo-cervical interaction was observed for the smooth response. Oscillating the body at a constant velocity (seesaw or ramp stimuli) revealed a frequency effect on the number of saccades (during a cycle of stimulation), but not on the gain of the response. Increasing the amplitude of oscillations augmented only very slightly the amplitude of saccades and consequently decreased the gain. Hence, the best working range of the saccadic response corresponds to body or head movements of low amplitude (up to +/- 20 deg) and low frequency (up to 0.25 Hz), and is improved by a visual input. These properties are discussed on a comparative point of view. It is proposed that, in chameleons, the saccadic response could contribute to gaze stabilization and add to the vestibulo-ocular and the optokinetic responses. PMID:9447697

  15. Analysis of vibration waveforms of electromechanical response to determine piezoelectric and electrostrictive coefficients.

    PubMed

    Izumi, Tatsuya; Hagiwara, Manabu; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki

    2012-08-01

    We developed a possible method to determine both coefficients of piezoelectricity (d) and electrostriction (M) at the same time by a waveform analysis of current and vibration velocity in the resonance state. The waveforms of the current and vibration velocity were theoretically described using the equations of motion and piezoelectric constitutive equations, considering the dissipation effect. The dissipation factor of the d coefficient and M coefficient is dielectric loss tangent tan ?. The waveforms measured in all of the ceramics, such as Pb(Zr,Ti)O(3) (PZT), Pb(Mg,Nb)O(3) (PMN), and 0.8Pb(Mg(1/3)Nb2/3)O(3)-0.2PbTiO(3) (PMN-PT), were well fitted with the calculated waveform. This fitting produced both the d and M coefficients, which agreed with those determined via the conventional methods. Moreover, the respective contributions of both piezoelectricity and electrostriction to the d value determined in the resonance-antiresonance method were clarified. PMID:22899111

  16. Epidemiological study of vibration syndrome in response to total hand-tool operating time.

    PubMed

    Miyashita, K; Shiomi, S; Itoh, N; Kasamatsu, T; Iwata, H

    1983-02-01

    The correlation between the severity of vibration syndrome and hand-tool operating time in chain saw workers has been studied. The total chain saw operating time was calculated by using the equation: chain saw operating hours/day X days/year X years, and 266 chain saw operators were classified into four groups (0-2000 h, 2000-5000 h, 5000-8000 h, over 8000 h). Forty-six forestry workers not using chain saws were used as controls. The prevalence rates of symptoms were checked and statistically compared in each group. In the group with under 2000 hours' experience, symptoms were generally confined to tingling, numbness, or pain; with 2000-5000 hours peripheral nerve and circulatory disturbances, including Raynaud's phenomenon, and muscle and general body conditions were influenced to some degree; with 5000-8000 hours' functional changes were noted; while with over 8000 hours about half the operators suffered severely from functional or organic changes due to vibration. PMID:6130782

  17. Vibration analyzer

    NASA Technical Reports Server (NTRS)

    Bozeman, Richard J., Jr. (inventor)

    1990-01-01

    The invention relates to monitoring circuitry for the real time detection of vibrations of a predetermined frequency and which are greater than a predetermined magnitude. The circuitry produces an instability signal in response to such detection. The circuitry is particularly adapted for detecting instabilities in rocket thrusters, but may find application with other machines such as expensive rotating machinery, or turbines. The monitoring circuitry identifies when vibration signals are present having a predetermined frequency of a multi-frequency vibration signal which has an RMS energy level greater than a predetermined magnitude. It generates an instability signal only if such a vibration signal is identified. The circuitry includes a delay circuit which responds with an alarm signal only if the instability signal continues for a predetermined time period. When used with a rocket thruster, the alarm signal may be used to cut off the thruster if such thruster is being used in flight. If the circuitry is monitoring tests of the thruster, it generates signals to change the thruster operation, for example, from pulse mode to continuous firing to determine if the instability of the thruster is sustained once it is detected.

  18. Responsibility attitudes and interpretations are characteristic of obsessive compulsive disorder

    Microsoft Academic Search

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

    2000-01-01

    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

  19. LINKING WITHIN-FIELD CROP RESPONSE WITH SOIL CHARACTERISTICS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management zones for precision farming can be determined by identifying areas where soil, water, and management factors result in similar crop responses. Given the spatial distribution of LAI of a field, factors determining response patterns may be obtained via inversion of a model linking environme...

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

    E-print Network

    Hwang, Harold Young

    2012-01-01

    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 ...

  1. Journalaf Sound and Vibration (1991) 145(3), 409-428 THE HARMONIC RESPONSE OF RECTANGULAR

    E-print Network

    Yaman, Yavuz

    1991-01-01

    at analyzing the response of a multi-bay stiffened structure were based on the normal mode approach. Knowledge of the natural frequencies and normal modes of such structures has generally been regarded, identifiable resonant response pe aks from appearing in the multi-mode acoustic response spectrum

  2. Comparative vibration environments of transportation vehicles

    NASA Technical Reports Server (NTRS)

    Stephens, D. G.

    1977-01-01

    Measured vibration data are presented for a number of air and surface vehicles. Consideration is given to the importance of direction effects; of vehicle operating modes such as takeoff, cruise, and landing; and of measurement location on the level and frequency of the measurements. Various physical measurement units or descriptors are used to quantify and compare the data. Results suggest the range of vibration associated with a particular mode of transportation and illustrate the comparative levels in terms of each of the descriptors. Collectively, the results form a data base which may be useful in assessing the ride of existing or future systems relative to vehicles in current operation. In addition, subjective response data obtained from vibration simulator studies are presented to illustrate human response characteristics as well as to indicate a laboratory approach for the development of ride-quality criteria.

  3. A stochastic averaging approach for printed circuit boards with nonlinear damping characteristics subjected to random vibration loads

    Microsoft Academic Search

    N. Hoffmann; L. Gaul

    2006-01-01

    Today many electronic devices consist of plate-like printed circuit boards carrying electric and electronic components mounted in some sort of housing. Depending on the application, these electronic devices may be subjected to severe random vibration loads over their lifetime, e.g. in automotive or aerospace environments. The present work shows that although state-of-the-art printed circuit boards are typically structurally linear with

  4. [Characteristics of work schedules of miners exposed to vibration in placer and ore mines in the North-West].

    PubMed

    Loginov, A A; Kim, G N

    1991-01-01

    The contributors review the peculiarities of modelling the labour regimen for the vibration-affected professions in the North-West, based on the dosage-related approach, inasmuch as the existing techniques of ore deposits elaboration (chamber-long face and magnification of ore), and the organization of pit works on cyclogrammes, did not allow a practical application of the labour regimen recommendations proposed by the USSR Ministry of Health. PMID:1817080

  5. Vestibular evoked myogenic potentials to sound and vibration: characteristics in vestibular migraine that enable separation from Menière’s disease

    Microsoft Academic Search

    Rachael L Taylor; Alessandro S Zagami; William PR Gibson; Deborah A Black; Michael G Halmagyi; Miriam S Welgampola

    2012-01-01

    Objectives: It can be difficult to distinguish vestibular migraine (VM) from Menière’s disease (MD) in its early stages. Using vestibular-evoked myogenic potentials (VEMPs), we sought to identify test parameters that would help discriminate between these two vestibular disorders.Methods: We first recorded ocular and cervical VEMPs (oVEMP\\/cVEMP) to air-conducted clicks and bone-conducted vibration in 30 control participants, 30 participants with clinically

  6. A hydraulic absorber for wideband vibration reduction in ship hulls

    SciTech Connect

    Hsueh, W.J.; Lee, Y.J. (National Taiwan Univ., Taipei (Taiwan, Province of China). Dept. of Naval Architecture and Ocean Engineering)

    1994-02-01

    A vibration reduction of ship hulls by an active absorber system is proposed. In the scheme, a tuned mass is moved according to the hull vibration as measured by a multi-mode sensing system in order to generate a suitable active force for vibration reduction of hull girder. In order to supply the large amount of required power, a hydraulic servo system is implemented. Then the dynamic characteristic of the hydraulic system is considered for system design. Based on stochastic theory and optimal theory, the control law of the system is derived in order to approach the optimal level of vibration reduction. A 10-t absorber is applied to a 87,000-t oil tanker to demonstrate the feasibility of this scheme. The results show that the multi-peak values of resonance are suppressed in frequency response. Moreover, the vibration excited by propeller and engine is reduced to an extremely efficient level by this scheme.

  7. Exploring Modeling Options and Conversion of Average Response to Appropriate Vibration Envelopes for a Typical Cylindrical Vehicle Panel with Rib-stiffened Design

    NASA Technical Reports Server (NTRS)

    Harrison, Phil; LaVerde, Bruce; Teague, David

    2009-01-01

    Although applications for Statistical Energy Analysis (SEA) techniques are more widely used in the aerospace industry today, opportunities to anchor the response predictions using measured data from a flight-like launch vehicle structure are still quite valuable. Response and excitation data from a ground acoustic test at the Marshall Space Flight Center permitted the authors to compare and evaluate several modeling techniques available in the SEA module of the commercial code VA One. This paper provides an example of vibration response estimates developed using different modeling approaches to both approximate and bound the response of a flight-like vehicle panel. Since both vibration response and acoustic levels near the panel were available from the ground test, the evaluation provided an opportunity to learn how well the different modeling options can match band-averaged spectra developed from the test data. Additional work was performed to understand the spatial averaging of the measurements across the panel from measured data. Finally an evaluation/comparison of two conversion approaches from the statistical average response results that are output from an SEA analysis to a more useful envelope of response spectra appropriate to specify design and test vibration levels for a new vehicle.

  8. Transient response characteristics of test chamber Mach number

    NASA Technical Reports Server (NTRS)

    Tcheng, P.

    1976-01-01

    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.

  9. Modelling of Haptic Vibration Textures with Infinite-Impulse-Response Filters

    E-print Network

    Lee, WonSook

    multiple frequencies of the response, and to unify the haptic texture model to arbitrary surfaces unlike the dominant frequency of the response as well as to unify the haptic texture model on arbitrary surfaces at high spatial frequency. Our unified model is general for any surface and simple to render with low

  10. Transient vibration phenomena in deep mine hoisting cables. Part 2: Numerical simulation of the dynamic response

    Microsoft Academic Search

    S. Kaczmarczyk; W. Ostachowicz

    2003-01-01

    A simulation model is presented which investigates the dynamic response of a deep mine hoisting cable system during a winding cycle. The response, namely the lateral motions of the catenary cable and the longitudinal motion of the vertical rope with conveyance is observed on the fast time scale, and the slow time scale is introduced to monitor the variation of

  11. Characteristics of antibody responses induced in mice by protein allergens

    Microsoft Academic Search

    J. Hilton; R. J. Dearman; N. Sattar; D. A. Basketter; I. Kimber

    1997-01-01

    Whereas many foreign proteins are immunogenic, only a proportion is also allergenic, having the capacity to induce the quality of immune response necessary to support the production of IgE antibody. We have demonstrated previously that intraperitoneal administration to mice of proteins such as ovalbumin (OVA) or the industrial enzyme A. oryzae lipase, which possess significant allergenic potential, stimulates the production

  12. School Refusal Behavior: Prevalence, Characteristics, and the Schools' Response.

    ERIC Educational Resources Information Center

    Stickney, Marcella I.; Miltenberger, Raymond G.

    1998-01-01

    A survey of 288 elementary and secondary North Dakota schools found 75% had a school refusal behavior (SRB) identification system in place, 57% had a school psychologist available, principals were most frequently responsible for identifying school refusers, 2.3% of students were identified as school refusers of which 49% falsely claimed illness,…

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

    SciTech Connect

    Yoshida, Tsutomu; Watanabe, Takeshi [Department of Mechanical Systems Engineering, Faculty of Engineering, Takushoku University, 815-1 Tatemachi, Hachioji, Tokyo (Japan)

    2014-05-27

    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.

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

    Microsoft Academic Search

    G. C. Mok; H. Namba

    1995-01-01

    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

  15. NIST torsion oscillator viscometer response: Performance on the LeRC active vibration isolation platform

    NASA Technical Reports Server (NTRS)

    Berg, Robert F.; Grodsinsky, Carlos M.

    1992-01-01

    Critical point viscosity measurements are limited to their reduced temperature approach to T(sub c) in an Earth bound system, because of density gradients imposed by gravity. Therefore, these classes of experiments have been proposed as good candidates for 'microgravity' science experiments where this limitation is not present. The nature of these viscosity measurements dictate hardware that is sensitive to low frequency excitations. Because of the vibratory acceleration sensitivity of a torsion oscillator viscometer, used to acquire such measurements, a vibration isolation sensitivity test was performed on candidate 'microgravity' hardware to study the possibility of meeting the stringent oscillatory sensitivity requirements of a National Institute of Standards and Technology (NIST) torsion oscillator viscometer. A prototype six degree of freedom active magnetic isolation system, developed at NASA Lewis Research Center, was used as the isolation system. The ambient acceleration levels of the platform were reduced to the noise floor levels of its control sensors, about one microgravity in the 0.1 to 10 Hz bandwidth.

  16. Responses to Mild Cold Stress Are Predicted by Different Individual Characteristics in Young and Older Subjects

    NSDL National Science Digital Library

    David W DeGroot (Pennsylvania State University Kinesiology)

    2006-12-01

    Journal article "Responses to Mild Cold Stress Are Predicted by Different Individual Characteristics in Young and Older Subjects", from the Journal of Applied Physiology, by David W. Degroot, W. Larry Kenny, and George Havenith.

  17. Electrical response characteristics of soil-electrolyte systems (10kHz-10MHz) 

    E-print Network

    Bachu, Umesh Kumar

    1997-01-01

    The electrical response characteristics of saturated soils depend on soil structure, particle orientation, effective particle size and size distribution, fluid type, fluid conductivity, volume fractions, etc. The use of ...

  18. Review of bubble detector response characteristics and results from space.

    PubMed

    Lewis, B J; Smith, M B; Ing, H; Andrews, H R; Machrafi, R; Tomi, L; Matthews, T J; Veloce, L; Shurshakov, V; Tchernykh, I; Khoshooniy, N

    2012-06-01

    A passive neutron-bubble dosemeter (BD), developed by Bubble Technology Industries, has been used for space applications. Both the bubble detector-personal neutron dosemeter and bubble detector spectrometer have been studied at ground-based facilities in order to characterise their response due to neutrons, heavy ion particles and protons. This technology was first used during the Canadian-Russian collaboration aboard the Russian satellite BION-9, and subsequently on other space missions, including later BION satellites, the space transportation system, Russian MIR space station and International Space Station. This paper provides an overview of the experiments that have been performed for both ground-based and space studies in an effort to characterise the response of these detectors to various particle types in low earth orbit and presents results from the various space investigations. PMID:21890528

  19. Wind response characteristics of horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Thresher, R. W.; Holley, W. E.; Jafarey, N.

    1981-01-01

    It was the objective of the work reported here, and in the companion paper 1 . A broader examination of wind turbine dynamic response to turbulence, and attempts to ascertain the features of turbulence that wind turbines are most sensitive to were made. A statistical description of the wind input including all three wind components and allowing linear wind gradients across the rotor disk, was used together with quasi-static aerodynamic theory and an elementary structural model involving only a few degrees of freedom. The idea was to keep the turbine model simple and show the benefits of this type of statistical wind representation before attempting to use a more complex turbine model. As far as possible, the analysis was kept in the simplest form, while still preserving key physical responses.

  20. Seed production characteristics and photoperiodic responses in buffelgrass: [Pennisetum ciliare L. (Link.)

    E-print Network

    Evers, Gerald Wayne

    1968-01-01

    SEED PRODUCTION CHARACTERISTICS AND PHQTOPERIODIC RESPONSES IN BUFFELGRASS [Pennisetum ciliare L, (Link. )] A Thesis GERALD W. EVERS Submitted to the Graduate College of the TEXAS ASM UNIVERSITY in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE M 1968 Major Subject: Agronomy SEED PRODHCTION CHARACTERISTICS AND PHOTOPERIODIC RESPONSES IN BUFFELGRASS [Pennisetum ciliare L. (Link. )j A Thesis by GERALD W. EVERS Approved as to style and content by: (Chairman...

  1. Electro-response characteristic of starch hydrogel crosslinked with Glutaraldehyde.

    PubMed

    Gao, Ling-Xiang; Chen, Jian-Li; Han, Xue-Wu; Yan, Shu-Xian; Zhang, Yan; Zhang, Wei-Qiang; Gao, Zi-Wei

    2015-06-01

    The facile synthesis of the starch hydrogel with anisotropic microstructure and dynamic behaviors was developed in the presence (A-gel) and absence of DC electric field (B-gel). The microstructures of hydrogels were characterized by environmental scanning electron microscope. Their electro-responsive property of hydrogels was investigated with their storage modulus (G'). The result demonstrates that the G' of A-gel is greater than that of B-gel, and the modulus of A-gel increases along with the external field, which signifies positive electroresponse. In addition, the G' of A-gel and B-gel ([Formula: see text] and [Formula: see text]) also continuously increases with increasing starch concentration, whereas both the maximum of modulus increment (?G' = [Formula: see text] - [Formula: see text]) and that of modulus increment sensitivity (?G'/[Formula: see text]) occur with the starch weight fraction at around 36.5%. To enhance the electro-responsive effects of the hydrogels, dielectric particles were dispersed in the hydrogel. It is found that BaTiO3/chitosan core-shell composite particles significantly enhance the electroresponse of the hydrogel. The mechanism of the electro-response mode is proposed. PMID:25849098

  2. Power-Generation Characteristics After Vibration and Thermal Stresses of Thermoelectric Unicouples with CoSb3/Ti/Mo(Cu) Interfaces

    NASA Astrophysics Data System (ADS)

    Bae, Kwang Ho; Choi, Soon-Mok; Kim, Kyung-Hun; Choi, Hyoung-Seuk; Seo, Won-Seon; Kim, Il-Ho; Lee, Soonil; Hwang, Hae Jin

    2015-06-01

    Reliability tests for thermoelectric unicouples were carried out to investigate the adhesion properties of CoSb3/Ti/Mo(Cu) interfaces. The n-type In0.25 Co3.95Ni0.05Sb12 and p-type In0.25Co3FeSb12 bulks were prepared for fabricating a thermoelectric unicouple (one p- n couple) by an induction melting and a spark plasma sintering process. Mo-Cu alloy was selected as an electrode for the unicouples due to its high melting temperature and proper work function value. Many thermoelectric unicouples with the CoSb3/Ti/Mo(Cu) interfaces were fabricated with the proper brazing materials by means of a repeated firing process. Reliability of the unicouples with the interfaces was evaluated by a vibration test and a thermal cycling test. After the thermal cycling and vibration tests, the power-generation characteristics of the unicouples were compared with the unicouples before the tests. Even after the vibration test, electrical power with a power density of 0.5 W/cm2 was generated. The Ti-interlayer is considered as a possible candidate for making a reliable unicouple with high adhesion strength. With the thermal cycling test, the resistance of the unicouple increased and the electrical power from the unicouple decreased. A failure mode by the thermal cycling test was ascribed to a complex effect of micro-cracks originated from the thermal stress and oxidation problem of the thermoelectric materials; that is, a thick oxide layer more than 300 ?m was detected after a high-temperature durability test of n-type In0.25Co3.95Ni0.05Sb12 material at 773 K in air for 7 days.

  3. Characteristic neurobiological patterns differentiate paternal responsiveness in two Peromyscus species.

    PubMed

    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

    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

  4. Electrical, optical and vibrational characteristics of nano structured yttrium barium stannous oxide synthesized through a modified combustion method

    SciTech Connect

    Vidya, S.; Rejith, P.P. [Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015, Kerala (India)] [Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015, Kerala (India); John, Annamma; Solomon, Sam [Dielectric Materials Research Laboratory, Department of Physics, St. John's College, Kollam District, Anchal 691306, Kerala (India)] [Dielectric Materials Research Laboratory, Department of Physics, St. John's College, Kollam District, Anchal 691306, Kerala (India); Deepa, A.S. [Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015, Kerala (India)] [Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015, Kerala (India); Thomas, J.K., E-mail: jkthomasemrl@yahoo.com [Electronic Materials Research Laboratory, Department of Physics, Mar Ivanios College, Thiruvananthapuram 695015, Kerala (India)

    2011-10-15

    Highlights: {yields} Synthesis of YBa{sub 2}SnO{sub 5.5} nano particles through a novel single step auto igniting combustion process. {yields} Phase purity, thermal stability, vibrational analysis, UV-vis absorption and photo luminescent studies were carried out. {yields} Chemical non-reactivity of YBa{sub 2}SnO{sub 5.5} with high T{sub c} superconductor YBCO was studied. -- Abstract: A single step combustion process for the preparation of nanoparticles of yttrium barium stannous oxide is reported in this paper. The structure, phase purity and particulate properties of the as prepared nano YBa{sub 2}SnO{sub 5.5} powder were examined by X-ray diffraction and transmission electron microscopy. The as prepared powder obtained itself is phase pure and possess cubic structure with lattice constant 8.240 A. The particle size of the as prepared sample from Transmission Electron Microscopy analysis is in the range of {approx}15 nm. Vibrational studies carried out on the as prepared powder also confirm the cubic structure of the as prepared sample. The thermal stability of the nano particle is analyzed by thermo gravimetric and differential thermal analysis. The material is a semiconductor with excellent luminescent properties. Chemical compatibility of the sample with YBCO is analyzed. The YBCO-YBa{sub 2}SnO{sub 5.5} composite showed T{sub c}(0) at 92 K.

  5. Road condition evaluation using the vibration response of ordinary vehicles and synchronously recorded movies

    NASA Astrophysics Data System (ADS)

    Nagayama, Tomonori; Miyajima, Akira; Kimura, Shunya; Shimada, Yuuki; Fujino, Yozo

    2013-04-01

    Frequent and quantitative assessment of road condition is important as the maintenance of the road infrastructure needs to be performed with a limited budget. Vehicle Intelligent Monitoring System (VIMS) has been developed to estimate an index of road ride comfort (International Roughness Index; IRI) by obtaining the acceleration responses of ordinary vehicles together with GPS position data. VIMS converts the vertical acceleration of the measurement vehicle to acceleration RMS of the sprung mass of the standard Quarter Car model, and then to IRI using an approximate expression. By driving over a hump of a known profile and comparing the responses with Quarter Car simulation responses, a variety of vehicles can be calibrated; a non-linear quarter car model equivalent to the vehicle is identified. By performing numerical simulation using the nonlinear vehicle model, the difference in driving speed can also be calibrated. The measurement results can be exported to maps to comprehend road condition in a geographical view and to other data base systems. In addition, smartphones which can record motions, GPS data, and movies synchronously are utilized to improve VIMS. Because practical installation locations of smartphones are limited and because angular velocity responses are less subjective to difference in installation locations, VIMS is extended to utilize the pitching angular velocity. Furthermore, high frequency components of acceleration responses are analyzed to distinguish local pavement damages or joints from rough road sections. The examination of synchronously recorded movies confirmed the capability to distinguish the local conditions.

  6. Characteristics of wind forces and responses of rectangular tall buildings

    NASA Astrophysics Data System (ADS)

    Amin, J. A.; Ahuja, A. K.

    2014-09-01

    This paper presents the results of wind tunnel tests on rectangular building models having the same plan area and height but different side ratios of 1, 1.56, 2.25, 3.06 and 4. The models were made from perspex sheet at a geometrical scale of 1:300. The wind pressure coefficients on all the models were evaluated from pressure records measured in a closed circuit wind tunnel under boundary layer flow for wind directions of 0° to 90° at an interval of 15°. The mean responses of rectangular tall buildings having different side ratios were also evaluated from the experimentally obtained wind loads. Effectiveness of side ratio of buildings in changing the surface pressure distribution and mean responses of prototype buildings is assessed for wind directions of 0° to 90° at an interval of 15°. It is observed that the side ratio of buildings significantly affects the wind pressures on leeward and sidewalls, whereas wind pressure on windward wall is almost independent of side ratio. Further, the wind incidence angles and side ratio of the buildings significantly affect its mean displacements as well as torque.

  7. Plant growth in controlled environments in response to characteristics of nutrient solutions

    NASA Technical Reports Server (NTRS)

    Raper, C. D., Jr.

    1982-01-01

    Plant growth in controlled environments in response to characteristics of nutrient solutions is discussed. Descriptions of experimental results concerning root acclimation to temperature, root and shoot acclimation to nitrogen stress, and growth response to NH4(+) and NO3(-) nutrition are included. A preliminary model validation to changing temperatures is presented.

  8. Migration Characteristics of Prostate Cancer Cells in Response to Epidermal Growth Factor (EGF)

    E-print Network

    Chiao, Jung-Chih

    Migration Characteristics of Prostate Cancer Cells in Response to Epidermal Growth Factor (EGF) S-efficient polydimethylsiloxane (PDMS)-based microfluidic device capable of monitoring the dynamics of cell migration in response time-lapsed interrogation of cell images to determine the numbers of cells migrating in different

  9. Noninvasive determination of bone mechanical properties using vibration response: A refined model and validation in vivo

    Microsoft Academic Search

    S. G. Roberts; T. M. Hutchinson; S. B. Arnaud; B. J. Kiratli; R. B. Martin; C. R. Steele

    1996-01-01

    Accurate non-invasive mechanical measurement of long bones is made difficult by the masking effect of surrounding soft tissues. Mechanical response tissue analysis (MRTA) offers a method for separating the effects of the soft tissue and bone; however, a direct validation has been lacking. A theoretical analysis of wave propagation through the compressed tissue revealed a strong mass effect dependent on

  10. 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)

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

    2014-09-01

    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.

  11. Measuring Fluctuating Pressure Levels and Vibration Response in a Jet Plume

    NASA Technical Reports Server (NTRS)

    Osterholt, Douglas J.; Knox, Douglas M.

    2011-01-01

    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.

  12. Effect of granular media on the vibrational response of a resonant structure: theory and experiment.

    PubMed

    Valenza, John J; Hsu, Chaur-Jian; Johnson, David Linton

    2010-11-01

    The acoustic response of a structure that contains a cavity filled with a loose granular material is analyzed. The inputs to the theory are the effective masses of each subsystem: that of the empty-cavity resonating structure and that of the granular medium within the cavity. This theory accurately predicts the frequencies, widths, and relative amplitudes of the various flexural mode resonances observed with rectangular bars, each having a cavity filled with loose tungsten granules. Inasmuch as the dominant mechanism for damping is due to adsorbed water at the grain-grain contacts, the significant effects of humidity on both the effective mass of the granular medium as well as on the response of the grain-loaded bars are monitored. Here, depending upon the humidity and the preparation protocol, it is possible to observe one, two, or three distinct resonances in a wide frequency range (1-5 kHz) over which the empty bar has but one resonance. These effects are understood in terms of the theoretical framework, which may simplify in terms of perturbation theories. PMID:21110572

  13. From monomers to ice - new vibrational characteristics of H 2O adsorbed on Pt(1 1 1)

    NASA Astrophysics Data System (ADS)

    Jacobi, K.; Bedürftig, K.; Wang, Y.; Ertl, G.

    2001-01-01

    H 2O adsorption on Pt(1 1 1) was studied by high-resolution electron energy loss spectroscopy over a wide exposure range at 85 K. We conclude that the known loss of the ice multilayer at about 30 meV is due to T ?4, the Pt-OH 2 translational mode perpendicular to the surface. This new assignment gives rise to a very consistent understanding of the vibrational spectra for thicker ice layers, for the bilayer, and for sub-monolayer coverages. For the bilayer two perpendicular modes are observed at 33 meV for the top H 2O molecule and at 16.5 meV for the bottom H 2O bonding to the surface Pt atom. For a new low-coverage phase only one T ? is found at 15 meV. Following a recent scanning tunneling microscopy result of Morgenstern et al. [1], the latter is assigned to H 2O monomers adsorbed in chains at the Pt(1 1 1) step edges. The newly observed monomer translation mode T ?1 at 15 meV can be used as an indicator for small amounts of H 2O co-adsorbed within O or OH layers.

  14. Flapping response characteristics of hingeless rotor blades by a gereralized harmonic balance method

    NASA Technical Reports Server (NTRS)

    Peters, D. A.; Ormiston, R. A.

    1975-01-01

    Linearized equations of motion for the flapping response of flexible rotor blades in forward flight are derived in terms of generalized coordinates. The equations are solved using a matrix form of the method of linear harmonic balance, yielding response derivatives for each harmonic of the blade deformations and of the hub forces and moments. Numerical results and approximate closed-form expressions for rotor derivatives are used to illustrate the relationships between rotor parameters, modeling assumptions, and rotor response characteristics. Finally, basic hingeless rotor response derivatives are presented in tabular and graphical form for a wide range of configuration parameters and operating conditions.

  15. [Defining characteristics of the dysfunctional ventilatory weaning response as indicators of accuracy of ventilatory weaning].

    PubMed

    Brandão, Marcos Antônio Gomes; Cerqueira, Fernanda Avellar; Matos, Ligia Neres; Campos, Juliana Faria; Peixoto, Mauricio Abreu Pinto; Primo, Cândida Caniçali

    2014-01-01

    The study aimed to analyze the defining characteristics of the Dysfunctional Ventilatory Weaning Response as an indicator of the accuracy of ventilatory weaning. Observational study of 38 events of ventilatory weaning in adult patients admitted to intensive care. For the defining characteristics, it was calculated: sensitivity, specificity, positive and negative predictive values, accuracy or efficiency, likelihood ratio positive and negative, and diagnostic odds ratio. It was also considered the median number of defining characteristics in the event of success and failure. It was considered accurate: agitation, deterioration in arterial blood gases from baseline parameters, moderate use of accessory muscles of respiration, increased respiratory rate from baseline parameters and respiratory rate increases significantly with respect to baseline parameters. There was statistical difference in the median number of defining characteristics observed. It was concluded that the defining characteristic and the number of them would influence the success of the weaning decision. PMID:25517667

  16. Transport properties and electroanalytical response characteristics of drotaverine ion-selective sensors

    Microsoft Academic Search

    Sergey V. Kharitonov

    2005-01-01

    The construction and electroanalytical response characteristics of poly(vinyl chloride) matrix ion-selective sensors (ISSs) for drotaverine hydrochloride are described. The membranes incorporate ion-association complexes of drotaverine with tetraphenylborate, picrate, tetraiodomercurate, tetraiodobismuthate, Reinecke salt, and heteropolycompounds of Keggin structure—molybdophosphoric acid, tungstophosphoric acid, molybdosiliconic acid and tungstosiliconic acid as electroactive materials for ionometric sensor controls. These ISSs have a linear response to drotaverine

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    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.

  18. Dynamic Response Characteristics of a Novel Electrolyte Michael C. Hollenbeck1,2

    E-print Network

    Stevens, Ken

    Dynamic Response Characteristics of a Novel Electrolyte Transistor Michael C. Hollenbeck1,2 , Hoda/IFTA, 3 Oakland University Abstract: Novel organic transistors utilizing acid/alkaline chemistry have been a multiphysics model for a polymer- electrolyte transistor (PET) simulated in COMSOL Multiphysics. Dynamic

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

    ERIC Educational Resources Information Center

    Allen, Jeff

    2012-01-01

    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…

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

    ERIC Educational Resources Information Center

    Latham, Alyson; Hill, N. Sharon

    2014-01-01

    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…

  1. String Vibrations

    NSDL National Science Digital Library

    Davidhazy, Andrew

    This site, by Andrew Davidhazy at the Rochester Institute of Technology, describes how to make interesting and artistic photographs of a vibrating string. Davidhazy explains how the string is vibrated, how the string is lit, and even the exposure time and the effect it has on the resulting image. Four images of the vibrating string are included.

  2. The global responses characteristics of a rotor/stator rubbing system with dry friction effects

    NASA Astrophysics Data System (ADS)

    Shang, Zhiyong; Jiang, Jun; Hong, Ling

    2011-05-01

    Rotor/stator rubbing systems may undertake a number of quite different responses. Recent experiments on rotor/stator rubbing have revealed that two or three different responses may coexist. In this paper the global response characteristics of a general rotor/stator rubbing system, which takes into account the dominant factors in the process of rotor/stator rubbing, especially, the dry friction effect that is mostly neglected in the previous works and is the main factor for the self-excited dry friction backward whirl, are studied. The different solutions of the piecewise nonlinear system are derived and their stability are analyzed to get the existence boundaries of the different responses. An overall picture of the global response characteristics of this model is then obtained by drawing the existence boundaries in a same parameter space. The present results provide good understanding on the coexistence of different rubbing responses observed in tests. Moreover, deeper insight into the types of coexistence of different rubbing responses and their relationship with the system parameters is gained.

  3. Limit-Cycle Vibrations In Turbomachinery

    NASA Technical Reports Server (NTRS)

    Ryan, S. G.

    1994-01-01

    Paper presents theoretical study of vibrations in high-speed turbomachinery. Addresses relationship between two classes of vibrational phenomena previously studied separately: dynamic instabilities, including both those subject to linear analysis and limit-cycle instabilities in cases of nonlinear vibrational response, and subharmonic response to excitation caused by unbalance of rotor.

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

    NASA Technical Reports Server (NTRS)

    Greenberg, Harry

    1947-01-01

    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.

  5. Using Surface Electromyography To Assess Sex Differences in Neuromuscular Response Characteristics

    PubMed Central

    Shultz, Sandra J.; Perrin, David H.

    1999-01-01

    Objective: To provide an overview of the continuum of muscular responses that typically occur with joint perturbation. The applications and limitations of surface electromyography (sEMG) in evaluating these responses are also addressed. Research applications assessing sex differences in these neuromuscular response characteristics are discussed along with suggestions for future research. Data Sources: MEDLINE was searched from 1969 through 1998. Sport DISCUS was searched from 1975 through 1998. Terms searched included “anterior cruciate ligament,” “epidemiology,” “neuromuscular control,” “neuromuscular performance,” “electromyography,” “latency,” “reflex,” “electromechanical delay,” “dynamic stability,” “intrinsic stiffness,” “short-range stiffness,” “muscle,” “mechanoreceptors,” and “reaction time.” Data Synthesis: It is widely accepted that efficient neuromuscular control is essential to dynamic joint stability and protection. Many studies have established the significant role of the muscles, and particularly the hamstrings, in providing knee stability. By observing the timing, phasing, and recruitment of reflexive muscular activation after a loading stress to the knee, we can better understand the coordinative mechanisms necessary to protect the joint and prevent ligament injury. A number of research models have employed the use of sEMG to evaluate neuromuscular responses at the knee after joint loading or perturbation. However, very few studies have specifically addressed potential sex differences in these response characteristics. Conclusions/Recommendations: From the limited research available, it appears that a sex difference may exist in some aspects of neuromuscular responses. However, further research is needed to explore these differences at the knee and their potential role as predisposing factors to the higher incidence of anterior cruciate ligament injuries in females. Future studies should examine sex differences in neuromuscular response characteristics at the knee under functional, weight-bearing conditions while controlling for training and other confounding variables. The limitations of sEMG should be considered when interpreting neuromuscular response studies. PMID:16558560

  6. Response surface methodology for predicting quality characteristics of beef patties added with flaxseed and tomato paste.

    PubMed

    Valenzuela Melendres, M; Camou, J P; Torrentera Olivera, N G; Alvarez Almora, E; González Mendoza, D; Avendaño Reyes, L; González Ríos, H

    2014-05-01

    Response surface methodology was used to study the effect of flaxseed flour (FS) and tomato paste (TP) addition, from 0 to 10% and 0 to 20% respectively, on beef patty quality characteristics. The assessed quality characteristics were color (L, a, and b), pH and texture profile analysis (TPA). Also, sensory analysis was performed for the assessment of color, juiciness, firmness, and general acceptance. FS addition reduced L and a values and decreased weight loss of cooked products (P<0.05). An opposite effect was observed when TP was added (P<0.05). All TPA parameters decreased when percentages of FS and TP were increased in the formulation of beef patties. Furthermore, FS and TP addition adversely affected the sensory characteristics of the cooked product (P<0.05); nevertheless, all sensory characteristics evaluated had an acceptable score (>5.6). Thus FS and TP are ingredients that can be used in beef patty preparation. PMID:24509360

  7. Torsional vibration reduction using passive nonlinear absorbers

    NASA Astrophysics Data System (ADS)

    Shaw, Steven W.; Alsuwaiyan, Abdallah

    2000-04-01

    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.

  8. A portable vibrator for muscle performance enhancement by means of direct muscle tendon stimulation.

    PubMed

    Luo, Jin; McNamara, Brian P; Moran, Kieran

    2005-07-01

    Combining vibration stimulation with conventional resistance training has gained in popularity. However, no portable vibrator capable of directly stimulating muscle tendon appears to feature in the literature. The aim of this study was the development of such a unit. The unit developed makes use of a rotating eccentric mass system to produce desired amplitude and frequency range capable of investigating the diverse vibration characteristics used in previous research studies. The effects of strapping force, joint angle and day-to-day repeatability on these vibration characteristics were investigated. In addition, muscle electromyography (EMG) activity was subsequently used to identify the optimum vibration amplitude and frequency. Finally, the repeatability of these EMG responses and effect of joint angle were examined. The unit was able to produce desired vibration characteristics (amplitude: 0.2-2 mm; frequency: 30-200 Hz). Test day, strapping force and joint angle had no significant effect on these characteristics (p>0.05). Both amplitudes (0.5 and 1.2 mm) and all three frequencies (30, 65 and 100 Hz) tested, significantly enhanced EMG activity (p<0.05), with 1.2 mm and both 65 and 100 Hz resulting in significantly greater enhancements (p<0.05). Joint angle had no significant effect on these EMG results (p>0.05). The day-to-day repeatability of EMG response was shown to be high (r=0.76-0.90). PMID:15990068

  9. PREFACE: Vibrations at surfaces Vibrations at surfaces

    NASA Astrophysics Data System (ADS)

    Rahman, Talat S.

    2011-12-01

    This special issue is dedicated to the phenomenon of vibrations at surfaces—a topic that was indispensible a couple of decades ago, since it was one of the few phenomena capable of revealing the nature of binding at solid surfaces. For clean surfaces, the frequencies of modes with characteristic displacement patterns revealed how surface geometry, as well as the nature of binding between atoms in the surface layers, could be different from that in the bulk solid. Dispersion of the surface phonons provided further measures of interatomic interactions. For chemisorbed molecules on surfaces, frequencies and dispersion of the vibrational modes were also critical for determining adsorption sites. In other words, vibrations at surfaces served as a reliable means of extracting information about surface structure, chemisorption and overlayer formation. Experimental techniques, such as electron energy loss spectroscopy and helium-atom-surface scattering, coupled with infra-red spectroscopy, were continually refined and their resolutions enhanced to capture subtleties in the dynamics of atoms and molecules at surfaces. Theoretical methods, whether based on empirical and semi-empirical interatomic potential or on ab initio electronic structure calculations, helped decipher experimental observations and provide deeper insights into the nature of the bond between atoms and molecules in regions of reduced symmetry, as encountered on solid surfaces. Vibrations at surfaces were thus an integral part of the set of phenomena that characterized surface science. Dedicated workshops and conferences were held to explore the variety of interesting and puzzling features revealed in experimental and theoretical investigations of surface vibrational modes and their dispersion. One such conference, Vibrations at Surfaces, first organized by Harald Ibach in Juelich in 1980, continues to this day. The 13th International Conference on Vibrations at Surfaces was held at the University of Central Florida, Orlando, in March 2010. Several speakers at this meeting were invited to contribute to the special section in this issue. As is clear from the articles in this special section, the phenomenon of vibrations at surfaces continues to be a dynamic field of investigation. In fact, there is a resurgence of effort because the insights provided by surface dynamics are still fundamental to the development of an understanding of the microscopic factors that control surface structure formation, diffusion, reaction and structural stability. Examination of dynamics at surfaces thus complements and supplements the wealth of information that is obtained from real-space techniques such as scanning tunneling microscopy. Vibrational dynamics is, of course, not limited to surfaces. Surfaces are important since they provide immediate deviation from the bulk. They display how lack of symmetry can lead to new structures, new local atomic environments and new types of dynamical modes. Nanoparticles, large molecules and nanostructures of all types, in all kinds of local environments, provide further examples of regions of reduced symmetry and coordination, and hence display characteristic vibrational modes. Given the tremendous advance in the synthesis of a variety of nanostructures whose functionalization would pave the way for nanotechnology, there is even greater need to engage in experimental and theoretical techniques that help extract their vibrational dynamics. Such knowledge would enable a more complete understanding and characterization of these nanoscale systems than would otherwise be the case. The papers presented here provide excellent examples of the kind of information that is revealed by vibrations at surfaces. Vibrations at surface contents Poisoning and non-poisoning oxygen on Cu(410)L Vattuone, V Venugopal, T Kravchuk, M Smerieri, L Savio and M Rocca Modifying protein adsorption by layers of glutathione pre-adsorbed on Au(111)Anne Vallée, Vincent Humblot, Christophe Méthivier, Paul Dumas and Claire-Marie Pradier Relating temperature dependence of atom

  10. Postural response to vibration of triceps surae, but not quadriceps muscles, differs between people with and without knee osteoarthritis.

    PubMed

    Shanahan, Camille J; Wrigley, Tim V; Farrell, Michael J; Bennell, Kim L; Hodges, Paul W

    2014-08-01

    Although proprioceptive impairments are reported in knee osteoarthritis (OA), there has been little investigation of the underlying causes. Muscle spindles make an important contribution to proprioception. This study investigated whether function of quadriceps, triceps surae, and tibialis anterior muscle spindles is altered in individuals with knee OA. Thirty individuals with knee OA (17 females, 66?±?7 [mean?±?SD] years) and 30 healthy asymptomatic controls (17 females, 65?±?8 years) stood comfortably and blindfolded on a force plate. Mechanical vibration (60?Hz) was applied bilaterally over the quadriceps, triceps surae, or tibialis anterior muscles for the middle 15?s (Vibration) of a 45?s trial (preceded and followed by 15?s Baseline and Recovery periods). Two trials were recorded for each muscle site. Mean anterior-posterior displacement of centre of pressure was analysed. Although there were no differences between groups for trials with vibration applied to the quandriceps or tibialis anterior, participants with knee OA were initially perturbed more by triceps surae vibration and accommodated less to repeated exposure than controls. This indicates that people with knee OA have less potential to detect or compensate for disturbed input to triceps surae, possibly due to an inability to compensate using muscles spindles in the quadriceps muscle. PMID:24797419

  11. Development of a numerical model for bridge–vehicle interaction and human response to traffic-induced vibration

    Microsoft Academic Search

    Hassan Moghimi; Hamid R. Ronagh

    2008-01-01

    The perceptible vibration of composite steel girder bridges under live loads is an important design consideration in today’s bridges, which have longer spans and lighter decks than older bridges, and have with limited damping. Although, in accordance with the bridge design codes, the strength design and the deflection control of these bridges are covered fairly well, vehicle movement on the

  12. 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)

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

    2014-12-01

    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.

  13. Seismic vibration analysis of fluid-structure interaction in LMFBR piping systems

    SciTech Connect

    Hara, F.

    1988-05-01

    This paper is a basic study on the vibrational characteristics of an LMFBR piping system containing liquid sodium under one-dimensional seismic excitation. Using Z-shaped piping, the authors formulate coupled equations for the pipe's bending vibration and pressure wave, and transform them into two-degree-of-freedom vibration equations for the first modes of the piping vibration and pressure wave. A numerical study using the vibration model shows that: 1) the coupling effect appears between piping acceleration and liquid pressure for a piping configuration having a natural frequency ratio ..nu.. = about 0.5 to 2.0; 2) the magnitude of seismically induced pressure reaches 0.7 kPa to 1 kPa per gal; and 3) the dead-mass model of liquid gives a nonconservative response depending on the pipe's geometrical configuration, compared to that from the pressure-wave-piping-interaction model.

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

    NASA Technical Reports Server (NTRS)

    Stephens, D. G.

    1977-01-01

    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.

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

    SciTech Connect

    Trudnowski, D.J.

    1992-12-01

    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.

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

    SciTech Connect

    Trudnowski, D.J.

    1992-12-01

    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.

  17. Response Characteristics of Scattered Light Aerosol Sensors Used for Control Monitoring

    Microsoft Academic Search

    JEROME P. SMITH; PAUL A. BARON; DONALD J. MURDOCK

    1987-01-01

    The response characteristics of scattered light aerosol monitors used in control monitoring applications were evaluated. In this report, “control monitoring” refers to continuous, fixed point monitoring used to ensure that dust controls are effective. Instruments evaluated included the following: an ATI-722, which uses a white light source; a RAM-S, which uses a LED source; and a PCAM-TX, which uses a

  18. Seismic response characteristics of full-size buildings with base isolation system

    Microsoft Academic Search

    C. Y. Wang; J. Gvildys

    1991-01-01

    This paper investigates the response characteristics of full-size reinforced concrete buildings via numerical simulations and actual observations. The test facility consists of two identical three-story buildings constructed side by side at Tohoku University in Sendai, Japan. Since the installation of high-damping isolation bearings in April 1989, data from over twenty earthquakes have been recorded. In this paper, three representative earthquake

  19. Influence of isolator characteristics on the response of base-isolated structures

    Microsoft Academic Search

    Vasant A. Matsagar; R. S. Jangid

    2004-01-01

    The influence of isolator characteristics on the seismic response of multi-story base-isolated structure is investigated. The isolated building is modeled as a shear type structure with lateral degree-of-freedom at each floor. The isolators are modeled by using two different mathematical models depicted by bi-linear hysteretic and equivalent linear elastic–viscous behaviors. The coupled differential equations of motion for the isolated system

  20. Nonlinear response and failure characteristics of internally pressurized composite cylindrical panels

    Microsoft Academic Search

    Boitnott

    1985-01-01

    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

  1. Meta-analysis of digital game and study characteristics eliciting physiological stress responses.

    PubMed

    van der Vijgh, Benny; Beun, Robbert-Jan; Van Rood, Maarten; Werkhoven, Peter

    2015-08-01

    Digital games have been used as stressors in a range of disciplines for decades. Nonetheless, the underlying characteristics of these stressors and the study in which the stressor was applied are generally not recognized for their moderating effect on the measured physiological stress responses. We have therefore conducted a meta-analysis that analyzes the effects of characteristics of digital game stressors and study design on heart rate, systolic and diastolic blood pressure, in studies carried out from 1976 to 2012. In order to assess the differing quality between study designs, a new scale is developed and presented, coined reliability of effect size. The results show specific and consistent moderating functions of both game and study characteristics, on average accounting for around 43%, and in certain cases up to 57% of the variance found in physiological stress responses. Possible cognitive and physiological processes underlying these moderating functions are discussed, and a new model integrating these processes with the moderating functions is presented. These findings indicate that a digital game stressor does not act as a stressor by virtue of being a game, but rather derives its stressor function from its characteristics and the methodology in which it is used. This finding, together with the size of the associated moderations, indicates the need for a standardization of digital game stressors. PMID:25950613

  2. Nonlinear Analysis and Experiments on Torsional Vibration of a Rotor with a Centrifugal Pendulum Vibration Absorber

    NASA Astrophysics Data System (ADS)

    Ishida, Yukio; Inoue, Tsuyoshi; Kagawa, Taishi; Ueda, Motohiko

    In the rotating machinery, such as automobile engines, the driving torque changes periodically and torsional vibrations occur. In this study, the dynamic characteristics of centrifugal pendulum vibration absorbers which are used to suppress torsional vibrations are investigated both theoretically and experimentally. In the theoretical analysis, the nonlinear characteristics are taken into consideration under the assumption that the pendulums vibrate with large amplitude. It is clarified that, although the centrifugal pendulum has remarkable effects on suppressing harmonic vibration, it induces large amplitude harmonic vibrations, the second and third order superharmonic resonances, and unstable vibrations of harmonic type under some condition,. Moreover, this paper proposes various methods to suppress these secondarily induced vibrations, and show that it is possible to suppress torsional vibrations to the substantially zero amplitude-level in the whole rotational speed range.

  3. Stability of response characteristics of a Delphi panel: application of bootstrap data expansion

    PubMed Central

    Akins, Ralitsa B; Tolson, Homer; Cole, Bryan R

    2005-01-01

    Background Delphi surveys with panels of experts in a particular area of interest have been widely utilized in the fields of clinical medicine, nursing practice, medical education and healthcare services. Despite this wide applicability of the Delphi methodology, there is no clear identification of what constitutes a sufficient number of Delphi survey participants to ensure stability of results. Methods The study analyzed the response characteristics from the first round of a Delphi survey conducted with 23 experts in healthcare quality and patient safety. The panel members had similar training and subject matter understanding of the Malcolm Baldrige Criteria for Performance Excellence in Healthcare. The raw data from the first round sampling, which usually contains the largest diversity of responses, were augmented via bootstrap sampling to obtain computer-generated results for two larger samples obtained by sampling with replacement. Response characteristics (mean, trimmed mean, standard deviation and 95% confidence intervals) for 54 survey items were compared for the responses of the 23 actual study participants and two computer-generated samples of 1000 and 2000 resampling iterations. Results The results from this study indicate that the response characteristics of a small expert panel in a well-defined knowledge area are stable in light of augmented sampling. Conclusion Panels of similarly trained experts (who possess a general understanding in the field of interest) provide effective and reliable utilization of a small sample from a limited number of experts in a field of study to develop reliable criteria that inform judgment and support effective decision-making. PMID:16321161

  4. 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)

    Cao, Bochao

    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.

  5. Numerical modeling of the dynamic response of prone-to-fall columns to ambient vibrations: comparison with measurements and potential application

    NASA Astrophysics Data System (ADS)

    Capron, Alexandre; Valentin, Johann; Jongmans, Denis; Baillet, Laurent; Larose, Eric; Bottelin, Pierre; Donze, Frédéric; Mangeney, Anne

    2015-04-01

    During the last two decades, seismic noise measurements have been increasingly used in gravitational hazard assessment for both investigation and monitoring purposes. The wide frequency range allows ambient vibrations to be applied for investigating geological and civil engineering structures in a great variety of sizes, from the lithospheric or crust scale to a few m-thick landslide and rock column or buildings. On unstable slopes, ambient vibrations have been applied in very different ways for reconnaissance, depending on the investigation purpose and the landslide type. The simplest way to extract information from ambient vibrations on a given site is to perform single-station measurements with a 3-C sensor and to process the records computing Fourier spectra of the three components or the spectral ratio between the horizontal and vertical components (the so-called H/V method). On landslide sites, several studies revealed significant spectral amplification at given frequency and polarization of the wave-field in the direction of maximum slope displacement. They show that different characteristics of the seismic noise (resonant frequencies, polarization, and spectral amplification) could be used from the spectral analysis of the motion or of spectral ratios for characterizing the landslides. For cliff-like sites, this study aims to identify the pertinent and applicable parameters that could be extracted from ambient vibrations and used to gain information on the prone-to-fall column geometry. We first use 2D numerical modeling for better understanding the influence of the rear fracture characteristics (wideness w and depth L) on the horizontal motion H(f), as well as on the spectral ratios H(f)/V(f) and H(f)/Hr(f), where Hr(f) is the horizontal motion measured at a reference site. We then identify the seismic parameters able to characterize the column decoupling and we compare numerical results to data acquired at two rocky sites exhibiting cliff-like geometry. During this study, the influence of other internal factors like presence of additional fractures and of an interbedded soft layer (Figure 1) is also tested.

  6. Localised muscle tissue oxygenation during dynamic exercise with whole body vibration.

    PubMed

    Robbins, Daniel; Elwell, Clare; Jimenez, Alfonso; Goss-Sampson, Mark

    2012-01-01

    Despite increasing use of whole body vibration during exercise an understanding of the exact role of vibration and the supporting physiological mechanisms is still limited. An important aspect of exercise analysis is the utilisation of oxygen, however, there have been limited studies considering tissue oxygenation parameters, particularly during dynamic whole body vibration (WBV) exercise. The aim of this study was to determine the effect of adding WBV during heel raise exercises and assessing changes in tissue oxygenation parameters of the lateral gastrocnemius using Near Infra Red Spectroscopy (NIRS). Twenty healthy subjects completed ten alternating sets of 15 heel raises (vibration vs. no vibration). Synchronous oxygenation and motion data were captured prior to exercise to determine baseline levels, for the duration of the exercise and 20 sec post exercise for the recovery period. Both vibration and no vibration conditions elicited a characteristic increase in deoxyhaemoglobin and decreases in oxyhaemoglobin, total haemoglobin, tissue oxygenation index and normalised tissue haemoglobin index which are indicative of local tissue hypoxia. However, the addition of vibration elicited significantly lower (p < 0. 001) depletions in oxyhaemoglobin, total haemoglobin, normalised tissue haemoglobin index but no significant differences in deoxyhaemoglobin. These findings suggest that addition of vibration to exercise does not increase the cost of the exercise for the lateral gastrocnemius muscle, but does decrease the reduction in local muscle oxygenation parameters, potentially resulting from increased blood flow to the calf or a vasospastic response in the feet. However, further studies are needed to establish the mechanisms underlying these findings. Key pointsWhole body vibration affects tissue oxygenation of the lateral gastrocnemius.The underlying mechanism could be either increased blood flow or a vasospastic response in the feet.The local metabolic cost of heel raise activity on the lateral gastrocnemius does not appear to be increased by whole body vibration. PMID:24149209

  7. Experimental Investigation of the Vibration Characteristics of Four Designs of Turbine Blades and of the Effect Produced by Varying the Axial Spacing Between Nozzle Blades and Turbine Blades.

    NASA Technical Reports Server (NTRS)

    Morgan, W C; Morse, C R

    1952-01-01

    An investigation was made to determine the effects of varying the spacing between the nozzle blades and the turbine blades of a turbo-jet engine on turbine-blade vibration for four turbine-blade designs of different degrees of stiffness. In general, there was a tendency toward increase in occurrence of vibration with decrease in spacing. The effect was most evident in the case of the turbine blades that had greater stiffness.

  8. Vibration isolation

    NASA Technical Reports Server (NTRS)

    Bastin, Paul

    1990-01-01

    Viewgraphs on vibration isolation are presented. Techniques to control and isolate centrifuge disturbances were identified. Topics covered include: disturbance sources in the microgravity environment; microgravity assessment criteria; life sciences centrifuge; flight support equipment for launch; active vibration isolation system; active balancing system; and fuzzy logic control.

  9. Good Vibrations

    NSDL National Science Digital Library

    OMSI

    2004-01-01

    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.

  10. Performance of some coupling methods for blast vibration monitoring

    NASA Astrophysics Data System (ADS)

    Segarra, P.; Sanchidrián, J. A.; Castedo, R.; López, L. M.; del Castillo, I.

    2015-01-01

    Field guidelines and recommendations for blasting vibration monitoring on a hard surface, suggest that the geophone mount should be coupled to the ground in a way that depends on the anticipated vibration level. However, the quantitative performance of the coupling method is basically unknown. In order to investigate this, the ground-to-mount coupling transmissibility (i.e. ratio of the response of the geophones mount to the rock motion, as a function of frequency) was measured between 16 and 200 Hz in 43 tests using a vibration exciter. The geophone mounts were freely placed, hold with a sandbag and anchored on granite. Free placed mounts applied outside the suggested range of vibrations (i.e. frequencies above 50-70 Hz at 5 mm/s) lead to the largest expected errors (up to 7.5 dB). Distortion is still significant (1.02 dB), though to a minor degree, at lower levels where this method is recommended. Sandbagging limits the maximum expected error to 1.6 dB, but it is ranked as the worst method irrespective of the vibration level and the sandbag planting at frequencies below 40 Hz. Anchoring appears as the only analyzed method that achieves a stiff rock-to-mount coupling, ensuring consistent measurements for the frequencies commonly found in blasting independently of the vibration level and the mount characteristics.

  11. Vibration modal analysis using all-optical photorefractive processing

    SciTech Connect

    Hale, T.; Telschow, K.

    1996-12-31

    A new experimental method for vibration modal analysis based on all- optical photorefractive processing is presented. The method utilizes an optical lock-in approach to measure phase variations in light scattered from optically rough, continuously vibrating surfaces. In this four-wave mixing technique, all-optical processing refers to mixing the object beam containing the frequency modulation due to vibration with a single frequency modulated pump beam in the photorefractive medium that processes the modulated signals. This allows for simple detection of the conjugate wavefront image at a CCD. The conjugate intensity is shown to be a function of the first-order ordinary Bessel function and linearly dependent on the vibration displacement induced phase. Furthermore, the results demonstrate the unique capabilities of the optical lock-in vibration detection technique to measure vibration signals with very narrow bandwidth (< 1 Hz) and high displacement sensitivity (sub-Angstrom). This narrow bandwidth detection can be achieved over a wide frequency range from the photorefractive response limit to the reciprocal of the photoinduced carrier recombination time. The technique is applied to determine the modal characteristics of a rigidly clamped circular disc from 10 kHz to 100 kHz.

  12. A numerical analysis of the influence of tram characteristics and rail profile on railway traffic ground-borne noise and vibration in the Brussels Region.

    PubMed

    Kouroussis, G; Pauwels, N; Brux, P; Conti, C; Verlinden, O

    2014-06-01

    Nowadays, damage potentially caused by passing train in dense cities is of increasing concern and restricts improvement to the interconnection of various public transport offers. Although experimental studies are common to quantify the effects of noise and vibration on buildings and on people, their reach is limited since the causes of vibrations can rarely be deduced from data records. This paper presents the numerical calculations that allow evaluating the main contributions of railway-induced ground vibrations in the vicinity of buildings. The reference case is the Brussels Region and, more particularly, the T2000 tram circulating in Brussels city. Based on a pertinent selection of the vibration assessment indicators and a numerical prediction approach, various results are presented and show that the free-field analysis is often improperly used in this kind of analysis as the interaction of soil and structure is required. Calculated high ground vibrations stem from singular rail surface defects. The use of resilient wheels is recommended in order to reduce the ground-borne noise and vibration to permissible values. PMID:23786851

  13. The characteristic time scale for basin hydrological response using radar data

    NASA Astrophysics Data System (ADS)

    Morin, Efrat; Enzel, Yehouda; Shamir, Uri; Garti, Rami

    2001-10-01

    The transformation of rainfall into runoff at a basin outlet is the combined effect of many hydrological processes, which occur at a wide range of spatial and temporal scales. However, determining the scale of the combined hydrological response of the basin is still problematic and concepts for its definition are yet to be identified. In this paper high-resolution meteorological radar data are used for the determination of a characteristic temporal scale for the hydrological response of the basin — the 'response time scale' (T s?). T s? is defined as the time scale at which the pattern of the time-averaged radar rainfall hietograph is most similar to the pattern of the measured outlet runoff hydrograph. The existence of such similarity at a relatively stable time scale for a specific basin indicates that it is an intrinsic property of the basin and is related to its hydrological response. The identification of the response time scale is carried out by analysis of observations only, without assuming a specific rainfall-runoff model. T s? is examined in four small basins (10-100 km 2) in Israel. The spatial scale is assumed as the entire basin. For all analyzed basins a stable response time scale is identified. Relatively short time scales are found for the urban and arid basins (15-30 min), while for the rural basins longer time scale are identified (90-180 min). The issues of relationship between the response time scale and basin properties and modeling at the response time scale have yet to be determined.

  14. Fourier Analysis Of Vibrations Of Round Structures

    NASA Technical Reports Server (NTRS)

    Davis, Gary A.

    1990-01-01

    Fourier-series representation developed for analysis of vibrations in complicated, round structures like turbopump impellers. Method eliminates guesswork involved in characterization of shapes of vibrational modes. Easy way to characterize complicated modes, leading to determination of responsiveness of given mode to various forcing functions. Used in conjunction with finite-element numerical simulation of vibrational modes of structure.

  15. Differential Responses to Food Price Changes by Personal Characteristic: A Systematic Review of Experimental Studies

    PubMed Central

    Mizdrak, Anja; Scarborough, Peter; Waterlander, Wilma E.; Rayner, Mike

    2015-01-01

    Background Fiscal interventions to improve population diet have been recommended for consideration by many organisations including the World Health Organisation and the United Nations and policies such as sugar-sweetened beverage taxes have been implemented at national and sub-national levels. However, concerns have been raised with respect to the differential impact of fiscal interventions on population sub-groups and this remains a barrier to implementation. Objective To examine how personal characteristics (such as socioeconomic status, sex, impulsivity, and income) moderate changes in purchases of targeted foods in response to food and beverage price changes in experimental settings. Design Systematic review Data Sources Online databases (PubMed, EMBASE, Web of Science, EconLit and PsycInfo), reference lists of previous reviews, and additional data from study authors. Study Selection We included randomised controlled trials where food and beverage prices were manipulated and reported differential effects of the intervention on participant sub-groups defined according to personal characteristics. Data Analysis Where possible, we extracted data to enable the calculation of price elasticities for the target foods by personal characteristic. Results 8 studies were included in the review. Across studies, the difference in price elasticity varied from 0.02 to 2.43 between groups within the same study. 11 out of the total of 18 comparisons of own-price elasticity estimates by personal characteristic differed by more than 0.2 between groups. Income related factors were the most commonly considered and there was an indication that own-price elasticity estimates do vary by income but the direction of this effect was not clear. Conclusion Experimental studies provide an opportunity to examine the differential effects of fiscal measures to improve population diets. Patterns in price sensitivity by personal characteristics are complex. General conclusions pertaining to the effects of personal characteristics on price sensitivity are not supported by the evidence, which shows heterogeneity between studies and populations. Trial Registration PROSPERO CRD42014009705 PMID:26151133

  16. Dynamic response characteristics of dual flow-path integrally bladed rotors

    NASA Astrophysics Data System (ADS)

    Beck, Joseph A.; Brown, Jeffrey M.; Scott-Emuakpor, Onome E.; Cross, Charles J.; Slater, Joseph C.

    2015-02-01

    New turbine engine designs requiring secondary flow compression often look to dual flow-path integrally bladed rotors (DFIBRs) since these stages have the ability to perform work on the secondary, or bypassed, flow-field. While analogous to traditional integrally bladed rotor stages, DFIBR designs have many differences that result in unique dynamic response characteristics that must be understood to avoid fatigue. This work investigates these characteristics using reduced-order models (ROMs) that incorporate mistuning through perturbations to blade frequencies. This work provides an alternative to computationally intensive geometric-mistuning approaches for DFIBRs by utilizing tuned blade mode reductions and substructure coupling in cyclic coordinates. Free and forced response results are compared to full finite element model (FEM) solutions to determine if any errors are related to the reduced-order model formulation reduction methods. It is shown that DFIBRs have many more frequency veering regions than their single flow-path integrally blade rotor (IBR) counterparts. Modal families are shown to transition between system, inner-blade, and outer-blade motion. Furthermore, findings illustrate that while mode localization of traditional IBRs is limited to a single or small subset of blades, DFIBRs can have modal energy localized to either an inner- or outer-blade set resulting in many blades responding above tuned levels. Lastly, ROM forced response predictions compare well to full FEM predictions for the two test cases shown.

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    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

  18. Compact Vibration Damper

    NASA Technical Reports Server (NTRS)

    Ivanco, Thomas G. (Inventor)

    2014-01-01

    A vibration damper includes a rigid base with a mass coupled thereto for linear movement thereon. Springs coupled to the mass compress in response to the linear movement along either of two opposing directions. A converter coupled to the mass converts the linear movement to a corresponding rotational movement. A rotary damper coupled to the converter damps the rotational movement.

  19. Six-Degree-of-Freedom Vibration Suppressor

    NASA Technical Reports Server (NTRS)

    Halwes, Dennis R.

    1987-01-01

    New system, total-rotor-isolation system (TRIS) employs liquid-inertia vibration-eliminator (LIVE) units, designed to isolate all six degrees of freedom of aircraft-fuselage dynamic response from continuously changing airloads developed by rotor. Vibration suppressor uses liquid mercury to damp vibrations. Results of flight tests indicated at least 95-percent reduction in vibration levels from rotor hub to pilot's seat.

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

    SciTech Connect

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

    1995-12-31

    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.

  1. Vibration Labs to Help Achieve a Resonance in Learning

    NSDL National Science Digital Library

    Cornwell, Philip

    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.

  2. Nonlinear vibration of cylindrical shells

    NASA Technical Reports Server (NTRS)

    Chen, J. C.; Babcock, C. D.

    1975-01-01

    The large amplitude vibration of a thin-walled cylindrical shell is analyzed. A perturbation method is used to solve the steady-state forced vibration problem. The simply-supported boundary conditions and the circumferential periodicity condition are satisfied. The resulting solution indicates that in addition to the fundamental mode, the response contains asymmetric modes as well as axisymmetric modes with the frequency twice that of the fundamental mode. Vibrations involving a single driven mode response are investigated. The results indicate that the nonlinearity is either softening or hardening depending on the mode. The vibrations involving both a driven mode and a companion mode are also investigated. An experimental investigation is conducted, and the results are in qualitative agreement with the theory. 'Nonstationary' response is detected at some frequencies for large amplitude response in which the amplitude drifts from one value to another. Various nonlinear phenomena are observed and comparisons with the theoretical results are made.

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

    Microsoft Academic Search

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

    1995-01-01

    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

  4. Approximating SIR-B response characteristics and estimating wave height and wavelength for ocean imagery

    NASA Technical Reports Server (NTRS)

    Tilley, David G.

    1987-01-01

    NASA Space Shuttle Challenger SIR-B ocean scenes are used to derive directional wave spectra for which speckle noise is modeled as a function of Rayleigh random phase coherence downrange and Poisson random amplitude errors inherent in the Doppler measurement of along-track position. A Fourier filter that preserves SIR-B image phase relations is used to correct the stationary and dynamic response characteristics of the remote sensor and scene correlator, as well as to subtract an estimate of the speckle noise component. A two-dimensional map of sea surface elevation is obtained after the filtered image is corrected for both random and deterministic motions.

  5. Characteristic-Wave Approach Complements Modal Analysis

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    1990-01-01

    Aspects of estimation of unmodeled dynamics discussed. Report discusses solution of nonhomogeneous governing matrix equation for dynamics of short vibrational pulses propagating as characteristic waves in large structure. Applied to analyze response, to repeated pulses, of beam clamped at one end and free at other. Shows all qualitative characteristics occuring under arbitrary periodic excitations of beam and those of quasi-periodic excitations, in as much as such excitations obtained by linear superpositions of periodic excitations.

  6. Wind-excited ovalling vibration of a thin circular cylindrical shell

    NASA Astrophysics Data System (ADS)

    Katsura, S.

    1985-06-01

    Vibration characteristics and growth mechanisms of wind-excited ovalling vibration of thin circular cylindrical shells which have dimensions like silos were investigated by using model shells made of polyester film in a wind tunnel. In the experiments wind pressure characteristics acting on the shell, static and dynamic responses of the shell and the effect of additional air force induced by the vibration of the shell were measured. The approaching flow used was uniform, with a turbulence intensity of only about 0·8%. In addition four kinds of turbulent flows were used in some experiments. The results obtained from this study suggest than the ovalling vibration of these kinds of shell is excited by an aerodynamic negative damping effect when the turbulence intensity of the approaching flow is small. The ovalling vibration occurred at velocities far lower than that for which the vortex shedding frequency would coincide with a natural frequency of vibration of the shell. The relationship between the inertia force of the shell and the mean lateral force acting on the shell at the onset of ovalling vibration is discussed.

  7. An experimental investigation of dual-resonant and non-resonant responses for vortex-induced vibration of a long slender cylinder

    NASA Astrophysics Data System (ADS)

    Wu, XiaoDong; Ge, Fei; Hong, YouShi

    2014-01-01

    Experimental results of the dual-resonant and non-resonant responses are presented for vortex-induced vibrations (VIV) of a long slender cylinder. The cylinder has a diameter of 10mm and a length of 3.31 m, giving an aspect ratio of 331. The cylinder was towed by a carriage with the velocity up to 1.5 m/s, with the Reynolds number varying from 2500 to 38000. Three different weights were used to provide the initial tension. Dual resonance means that resonance occurs simultaneously in both the cross-flow (CF) and in-line (IL) directions. The experiments were conducted in two stages. At the first stage, dual-resonant dynamic features of the cylinder subjected to vortex-induced excitation were investigated. The features of CF and IL vibration amplitude, motion orbits, phase angle differences, dominant frequencies and mode order numbers are presented. At the second stage of the experiments, particular emphasis was placed on non-resonant dynamic features. The variation of multi-mode modal displacement amplitudes was investigated in detail.

  8. Nonlinear response and failure characteristics of internally pressurized composite cylindrical panels

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  9. Comprehensive studies of response characteristics of organic photodetectors based on rubrene and C{sub 60}

    SciTech Connect

    Yang, Dezhi; Xu, Kai; Zhou, Xiaokang; Wang, Yanping; Ma, Dongge, E-mail: mdg1014@ciac.ac.cn [State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022 (China)

    2014-06-28

    We studied the transient response characteristics of organic photodetectors composing of high mobility materials of rubrene and C{sub 60}, 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 C{sub 60}, which should account for the negative dependence of bandwidth on the reverse bias in rubrene-based device.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  11. Poroelastic response of articular cartilage by nanoindentation creep tests at different characteristic lengths.

    PubMed

    Taffetani, M; Gottardi, R; Gastaldi, D; Raiteri, R; Vena, P

    2014-07-01

    Nanoindentation is an experimental technique which is attracting increasing interests for the mechanical characterization of articular cartilage. In particular, time dependent mechanical responses due to fluid flow through the porous matrix can be quantitatively investigated by nanoindentation experiments at different penetration depths and/or by using different probe sizes. The aim of this paper is to provide a framework for the quantitative interpretation of the poroelastic response of articular cartilage subjected to creep nanoindentation tests. To this purpose, multiload creep tests using spherical indenters have been carried out on saturated samples of mature bovine articular cartilage achieving two main quantitative results. First, the dependence of indentation modulus in the drained state (at equilibrium) on the tip radius: a value of 500 kPa has been found using the large tip (400 ?m radius) and of 1.7 MPa using the smaller one (25 ?m). Secon, the permeability at microscopic scale was estimated at values ranging from 4.5×10(-16) m(4)/N s to 0.1×10(-16) m(4)/N s, from low to high equivalent deformation. Consistently with a poroelastic behavior, the size-dependent response of the indenter displacement disappears when characteristic size and permeability are accounted for. For comparison purposes, the same protocol was applied to intrinsically viscoelastic homogeneous samples of polydimethylsiloxane (PDMS): both indentation modulus and time response have been found size-independent. PMID:24814573

  12. Differential Weight Procedure of the Conditional P.D.F. Approach for Estimating the Operating Characteristics of Discrete Item Responses.

    ERIC Educational Resources Information Center

    Samejima, Fumiko

    A method is proposed that increases the accuracies of estimation of the operating characteristics of discrete item responses, especially when the true operating characteristic is represented by a steep curve, and also at the lower and upper ends of the ability distribution where the estimation tends to be inaccurate because of the smaller number…

  13. 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

    Kurup, Priya Darshini

    2012-02-14

    Characteristics Corporate Social Responsibility Corporate Social Responsibility Orientation Ergonomics Equipment Use Feedback From Job Feedback From Others Interdependence Interaction Outside the Organization Information Processing Job Complexity... have focused on a narrow set of outcomes that was partially propelled by emphasis on the outcomes determined by the disciplines of interest, such as industrial/organizational psychology, supply chain, biomechanics, and ergonomics (Campion, 1988...

  14. Quantitative response characteristics of thermoreceptive and nociceptive lamina I spinothalamic neurons in the cat.

    PubMed

    Craig, A D; Krout, K; Andrew, D

    2001-09-01

    The physiological characteristics of antidromically identified lamina I spinothalamic (STT) neurons in the lumbosacral spinal cord were examined using quantitative thermal and mechanical stimuli in barbiturate-anesthetized cats. Cells belonging to the three main recognized classes were included based on categorization with natural cutaneous stimulation of the hindpaw: nociceptive-specific (NS), polymodal nociceptive (HPC), or thermoreceptive-specific (COOL) cells. The mean central conduction latencies of these classes differed significantly; NS = 130.8 +/- 55.5 (SD) ms (n = 100), HPC = 72.1 +/- 28.0 ms (n = 128), and COOL = 58.6 +/- 25.3 ms (n = 136), which correspond to conduction velocities of 2.5, 4.6, and 5.6 m/s. Based on recordings made prior to any noxious stimulation, the mean spontaneous discharge rates of these classes also differed: NS = 0.5 +/- 0.7 imp/s (n = 47), HPC = 0.9 +/- 0.7 imp/s (n = 59), and COOL = 3.3 +/- 2.6 imp/s (n = 107). Standard, quantitative, thermal stimulus sequences applied with a Peltier thermode were used to characterize the stimulus-response functions of 76 COOL cells, 47 HPC cells, and 37 NS cells. The COOL cells showed a very linear output from 34 degrees C down to approximately 15 degrees C and a maintained plateau thereafter. The HPC cells showed a fairly linear but accelerating response to cold below a median threshold of approximately 24 degrees C and down to 9 degrees C (measured at the skin-thermode interface with a thermode temperature of 2 degrees C). The HPC cells and the NS cells both showed rapidly increasing, sigmoidal response functions to noxious heat with a fairly linear response between 45 and 53 degrees C, but they had significantly different thresholds; half of the HPC cells were activated at ~45.5 degrees C and half of the NS cells at approximately 43 degrees C. The 20 HPC lamina I STT cells and 10 NS cells tested with quantitative pinch stimuli showed fairly linear responses above a threshold of approximately 130 g/mm(2) for HPC cells and a threshold of approximately 100 g/mm(2) for NS cells. All of these response functions compare well (across species) with the available data on the characteristics of thermoreceptive and nociceptive primary afferent fibers and the appropriate psychophysics in humans. Together these results support the concept that these classes of lamina I STT cells provide discrete sensory channels for the sensations of temperature and pain. PMID:11535691

  15. Characteristics of SIP Response for Rock Specimens in the Gagok Skarn Deposit, Korea

    NASA Astrophysics Data System (ADS)

    Kim, C.; Mi Kyung, P.; Park, S.; Shin, S.

    2012-12-01

    Spectral Induced Polarization (SIP) method was conducted to develop mineral exploration technique in the Gagok skarn deposit, Korea. The Gagok mine was once abandoned and recently reopened. The Gagok stratabound skarn deposit is originated from the Cretaceous granite intrusion into the Paleozoic limestone and slate formations. The ore minerals of the Gagok deposit include sulfide minerals such as sphalerite, pyrrhotite, galena, chalcopyrite, pyrite, arsenopyrite, etc. The characteristics of SIP response for the rock specimens were examined to re-evaluate mineral resources. Total 104 rock specimens were obtained from the mine shafts at the various elevations, and were modified in cylindrical shape for the measurement of SIP response, along with other physical properties such as porosity, density, DC electrical resistivity, magnetic susceptibility, and seismic velocity. The SIP measurement system consists of electrical current transmitter and receiver (model GDP-32 system, Zonge Co. USA), and measures amplitude for resistivity, and phase at 14 steps of frequencies ranging from 0.125 to 1,024 Hz. The results of the SIP measurement shows that the rock specimens from ore bodies accompanied with sulfide minerals such as sphalerite and pyrite produce large phase differences with frequencies applied. The results also show that the rock specimens at the lower elevation of the mine shaft have stronger SIP response and mineralization. The rock specimens with large phase differences of strong SIP response were classified into three phase curve types, based on the range of critical frequency from the SIP measurement. (1) Curve type 1: critical frequency of less than 1 Hz with decreasing phase curve (2) Curve type 2: critical frequency of 1 to 10 Hz with bell shape, (3) Curve type 3: critical frequency of larger than 10 Hz with mixture of curve type 1 and 2. It is believed that the graphitic components and sulfide minerals such as sphalerite and pyrite are dominant in the rock specimens with curve type 1 and 2, respectively, and that the mixed components of graphitic and sulfide minerals mainly consist of rock specimens with curve type 3. The analysis of mineral components for the rock specimens is currently being conducted in the laboratory. The results of the mineral analysis will provide more clear information regarding the relationship between SIP response and mineral composition, particularly, sulfide minerals for the rock specimens. In the future study, the analysis of the characteristics of the SIP response, integrated with lithological study for the ore bodies would improve mineral exploration development techniques in the skarn ore deposits.

  16. The Effects of Impact Vibration on Peripheral Blood Vessels and Nerves

    PubMed Central

    KRAJNAK, Kristine M.; WAUGH, Stacey; JOHNSON, Claud; MILLER, G. Roger; XU, Xueyan; WARREN, Christopher; DONG, Ren G.

    2013-01-01

    Research regarding the risk of developing hand-arm vibration syndrome after exposure to impact vibration has produced conflicting results. This study used an established animal model of vibration-induced dysfunction to determine how exposure to impact vibration affects peripheral blood vessels and nerves. The tails of male rats were exposed to a single bout of impact vibration (15 min exposure, at a dominant frequency of 30?Hz and an unweighted acceleration of approximately 345 m/s2) generated by a riveting hammer. Responsiveness of the ventral tail artery to adrenoreceptor-mediated vasoconstriction and acetylcholine-mediated re-dilation was measured ex vivo. Ventral tail nerves and nerve endings in the skin were assessed using morphological and immunohistochemical techniques. Impact vibration did not alter vascular responsiveness to any factors or affect trunk nerves. However, 4 days following exposure there was an increase in protein-gene product (PGP) 9.5 staining around hair follicles. A single exposure to impact vibration, with the exposure characteristics described above, affects peripheral nerves but not blood vessels. PMID:24077447

  17. Fiber optic vibration sensor

    DOEpatents

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

    1995-01-01

    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.

  18. Fiber optic vibration sensor

    DOEpatents

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

    1995-01-10

    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.

  19. Vibration sensors

    NASA Astrophysics Data System (ADS)

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

    2003-10-01

    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.

  20. Vibration disease.

    PubMed

    Kákosy, T

    1989-04-01

    Today, in this age of technology, vibration caused by machinery is an almost universal hazard. Vibration transferred from a machine to the human body may cause discomfort, a reduction of performance, and even injury. Vibratory manual tools may cause damage to the circulatory system of the upper extremities (Raynaud's syndrome), to the peripheral nerves (peripheral neuropathy), and to the bones and joints (aseptic necrosis, fatigue fractures, degenerative joint disease). Vehicles and machines causing floor vibration cause degenerative disc disease of the lumbar spine. The pathogenesis of vibration injuries is still not completely clear and there is no effective treatment. Some of the abnormalities are irreversible and may cause permanent decrease of working ability, and even unemployment. This is why prevention is so important. Prevention is complex, including technical and organizational measures, use of individual protective clothing and footwear, and medical supervision both before and during employment. Workers who are exposed to vibration should be protected against other aggravating factors such as cold and noise, etc. Vibration-induced injuries are recognized in law in many countries as grounds for financial compensation. Their cost to industry is rising and, unless a means of prevention or cure is found, will continue to do so in the foreseeable future. PMID:2661029

  1. A Canonical Response in Rainfall Characteristics to Global Warming: Projections by IPCC CMIP5 Models

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Wu, H. T.; Kim, K. M.

    2012-01-01

    Changes in rainfall characteristics induced by global warming are examined based on probability distribution function (PDF) analysis, from outputs of 14 IPCC (Intergovernmental Panel on Climate Change), CMIP (5th Coupled Model Intercomparison Project) models under various scenarios of increased CO2 emissions. Results show that collectively CMIP5 models project a robust and consistent global and regional rainfall response to CO2 warming. Globally, the models show a 1-3% increase in rainfall per degree rise in temperature, with a canonical response featuring large increase (100-250 %) in frequency of occurrence of very heavy rain, a reduction (5-10%) of moderate rain, and an increase (10-15%) of light rain events. Regionally, even though details vary among models, a majority of the models (>10 out of 14) project a consistent large scale response with more heavy rain events in climatologically wet regions, most pronounced in the Pacific ITCZ and the Asian monsoon. Moderate rain events are found to decrease over extensive regions of the subtropical and extratropical oceans, but increases over the extratropical land regions, and the Southern Oceans. The spatial distribution of light rain resembles that of moderate rain, but mostly with opposite polarity. The majority of the models also show increase in the number of dry events (absence or only trace amount of rain) over subtropical and tropical land regions in both hemispheres. These results suggest that rainfall characteristics are changing and that increased extreme rainfall events and droughts occurrences are connected, as a consequent of a global adjustment of the large scale circulation to global warming.

  2. Fuel assembly self-excited vibration and test methodology

    SciTech Connect

    Lu, R.Y.; Broach, K. D.; McEvoy, J. J. [PWR Product Technologies, Westinghouse Electric Company, Drawer R, Columbia, SC, 29250 (United States)

    2004-07-01

    PWR fuel assemblies normally experience low amplitude, random vibration under normal reactor flow conditions. This normal fuel assembly vibration has almost no impact on grid-rod fretting wear. However, some fuel assembly designs experience a high resonant fuel assembly vibration under normal axial flow conditions. This anomalous fuel assembly vibration is defined as fuel assembly self-excitation vibration (FASE), because the assembly vibrates resonantly without any external periodic excitation force. Fuel assembly self-excitation vibration can cause severe grid-rod fretting if the assembly operates at the flow rate, which causes high fuel assembly vibration. This paper will describe the characteristics of fuel assembly self-excitation vibration and the test methodology to identify the fuel assembly vibration. Several fuel assembly designs are compared under standard test conditions. The causes for the fuel assembly self-excitation vibration are analyzed and discussed. The test acceptance criteria are defined for newly developed PWR fuel assemblies. (authors)

  3. Apparatus and method of preloading vibration-damping bellows

    DOEpatents

    Cutburth, Ronald W. (Tracy, CA)

    1988-01-01

    An improved vibration damping bellows mount or interconnection is disclosed. In one aspect, the bellows is compressively prestressed along its length to offset vacuum-generated tensile loads and thereby improve vibration damping characteristics.

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    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.

  6. Random Vibrations

    NASA Technical Reports Server (NTRS)

    Messaro. Semma; Harrison, Phillip

    2010-01-01

    Ares I Zonal Random vibration environments due to acoustic impingement and combustion processes are develop for liftoff, ascent and reentry. Random Vibration test criteria for Ares I Upper Stage pyrotechnic components are developed by enveloping the applicable zonal environments where each component is located. Random vibration tests will be conducted to assure that these components will survive and function appropriately after exposure to the expected vibration environments. Methodology: Random Vibration test criteria for Ares I Upper Stage pyrotechnic components were desired that would envelope all the applicable environments where each component was located. Applicable Ares I Vehicle drawings and design information needed to be assessed to determine the location(s) for each component on the Ares I Upper Stage. Design and test criteria needed to be developed by plotting and enveloping the applicable environments using Microsoft Excel Spreadsheet Software and documenting them in a report Using Microsoft Word Processing Software. Conclusion: Random vibration liftoff, ascent, and green run design & test criteria for the Upper Stage Pyrotechnic Components were developed by using Microsoft Excel to envelope zonal environments applicable to each component. Results were transferred from Excel into a report using Microsoft Word. After the report is reviewed and edited by my mentor it will be submitted for publication as an attachment to a memorandum. Pyrotechnic component designers will extract criteria from my report for incorporation into the design and test specifications for components. Eventually the hardware will be tested to the environments I developed to assure that the components will survive and function appropriately after exposure to the expected vibration environments.

  7. The sense of flutter-vibration evoked by stimulation of the hairy skin of primates: Comparison of human sensory capacity with the responses of mechanoreceptive afferents innervating the hairy skin of monkeys

    Microsoft Academic Search

    Michael M. Merzenich; Thomas Harrington

    1969-01-01

    We have studied the response properties of peripheral myelinated fibers ending in the hairy skin of the Rhesus monkey, activated by sinusoidal mechanical stimulation. In parallel experiments we measured thresholds of the sensations evoked in man by identical stimuli, delivered under similar conditions to corresponding areas of the hairy skin. We found that the sense of low frequency vibration (i.

  8. Analytical and experimental investigations on vibration control mechanisms for flexible active structures

    NASA Astrophysics Data System (ADS)

    Lin, Rongming; Nyang, Koon M.

    2002-11-01

    The study of smart structures with active devices of sensors and actuators for self-monitoring and self-adaption has been of much recent research interest. Active vibration control is a major application focus and there has been tremendous amount of research work on active vibration control of flexible structures using piezoelectric materials. In this paper, the control mechanism for a flexible cantilever plate structure using surface bonded piezoelectric sensors and actuators has been studied through analytical simulations and experiments. The sensor outputs were used to determine the amount of input to the actuators for controlling the response of the structure in a closed loop. The responses under different control mechanisms were analysed by three dimensional finite element model. The effectiveness of different feedback control methods in altering system characteristics and system responses of the structure was investigated. Experimental investigations on active vibration control were also conducted on a cantilever plate with surface bonded piezoelectric sensors and actuators.

  9. Temporal characteristics of gustatory responses in rat parabrachial neurons vary by stimulus and chemosensitive neuron type.

    PubMed

    Geran, Laura; Travers, Susan

    2013-01-01

    It has been demonstrated that temporal features of spike trains can increase the amount of information available for gustatory processing. However, the nature of these temporal characteristics and their relationship to different taste qualities and neuron types are not well-defined. The present study analyzed the time course of taste responses from parabrachial (PBN) neurons elicited by multiple applications of "sweet" (sucrose), "salty" (NaCl), "sour" (citric acid), and "bitter" (quinine and cycloheximide) stimuli in an acute preparation. Time course varied significantly by taste stimulus and best-stimulus classification. Across neurons, the ensemble code for the three electrolytes was similar initially but quinine diverged from NaCl and acid during the second 500 ms of stimulation and all four qualities became distinct just after 1s. This temporal evolution was reflected in significantly broader tuning during the initial response. Metric space analyses of quality discrimination by individual neurons showed that increases in information (H) afforded by temporal factors was usually explained by differences in rate envelope, which had a greater impact during the initial 2s (22.5% increase in H) compared to the later response (9.5%). Moreover, timing had a differential impact according to cell type, with between-quality discrimination in neurons activated maximally by NaCl or citric acid most affected. Timing was also found to dramatically improve within-quality discrimination (80% increase in H) in neurons that responded optimally to bitter stimuli (B-best). Spikes from B-best neurons were also more likely to occur in bursts. These findings suggest that among PBN taste neurons, time-dependent increases in mutual information can arise from stimulus- and neuron-specific differences in response envelope during the initial dynamic period. A stable rate code predominates in later epochs. PMID:24124597

  10. The genetic influences on oxycodone response characteristics in human experimental pain.

    PubMed

    Olesen, Anne E; Sato, Hiroe; Nielsen, Lecia M; Staahl, Camilla; Droney, Joanne; Gretton, Sophy; Branford, Ruth; Drewes, Asbjørn M; Arendt-Nielsen, Lars; Riley, Julia; Ross, Joy

    2015-08-01

    Human experimental pain studies are of value to study basic pain mechanisms under controlled conditions. The aim of this study was to investigate whether genetic variation across selected mu-, kappa- and delta-opioid receptor genes (OPRM1, OPRK1and OPRD1, respectively) influenced analgesic response to oxycodone in healthy volunteers. Experimental multimodal, multitissue pain data from previously published studies carried out in Caucasian volunteers were used. Data on thermal skin pain tolerance threshold (PTT) (n = 37), muscle pressure PTT (n = 31), mechanical visceral PTT (n = 43) and thermal visceral PTT (n = 41) were included. Genetic associations with pain outcomes were explored. Nineteen opioid receptor genetic polymorphisms were included in this study. Variability in oxycodone response to skin heat was associated with OPRM1 single-nucleotide polymorphisms (SNPs) rs589046 (P < 0.0001) and rs563649 (P < 0.0001). Variability in oxycodone response to visceral pressure was associated with four OPRM1 SNPs: rs589046 (P = 0.015), rs1799971 (P = 0.045), rs9479757 (P = 0.009) and rs533586 (P = 0.046). OPRM1 SNPs were not associated with oxycodone visceral heat threshold, however, one OPRD1 rs419335 reached significance (P = 0.015). Another OPRD1 SNP rs2234918 (P = 0.041) was associated with muscle pressure. There were no associations with OPRK1 SNPs and oxycodone response for any of the pain modalities. Associations were found between analgesic effects of oxycodone and OPRM1 and OPRD1 SNPs; therefore, variation in opioid receptor genes may partly explain responder characteristics to oxycodone. PMID:26042474

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

    SciTech Connect

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

    1991-01-01

    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.

  12. Dependence of the South tropical Pacific response to varying ENSO characteristics

    NASA Astrophysics Data System (ADS)

    Leloup, Julie; Lengaigne, Matthieu; Braconnot, Pascale; Guilyardi, Éric

    2013-04-01

    ENSO teleconnections in the South Pacific are likely to depend on the characteristics of ENSO events (i.e. intensity, seasonality, spatial patterns, etc). There is hence a need to further investigate those teleconnections in order to better qualify and understand relationship between the variability of proxies in this region and ENSO. In this study, we first analyze both the sea surface temperature and sea surface salinity as observed over the recent period to qualify and quantify the specific contributions of ENSO to the South Pacific climate variability. Those analyses are then extended to long-term climate simulations from the CMIP5 database to assess the ability of coupled models to simulate these teleconnections and further understand the mechanisms driving the surface response to ENSO events in the South Pacific.

  13. Dynamic response characteristics of a circulation control rotor model pneumatic system

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    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.

  14. Fuselage shell and cavity response measurements on a DC9 test section

    Microsoft Academic Search

    M. A. Simpson; G. P. Mathur; M. R. Cannon; B. N. Tran; P. L. Burge

    1991-01-01

    A series of fuselage shell and cavity response measurements conducted on a DC-9 aircraft test section are described. The objectives of these measurements were to define the shell and cavity model characteristics of the fuselage, understand the structural-acoustic coupling characteristics of the fuselage, and measure the response of the fuselage to different types of acoustic and vibration excitation. The fuselage

  15. Acoustic vibration induced high electromagnetic responses of Fe3O4 nano-hollow spheres in the THz regime

    NASA Astrophysics Data System (ADS)

    Rakshit, Rupali; Sarkar, Debasish; Pal, Monalisa; Serite, Kazunori; Tonouchi, Masayoshi; Mandal, Kalyan

    2015-06-01

    Herein, we investigate the origin of enhanced absorption and complex conductivity of magnetite (Fe3O4) nano-hollow spheres (NHSs) in contrast to its nanoparticles (NPs) configuration in the frequency range 0.4–2.0?THz. The maximum absorption for NHSs and NPs of the same average diameter (~100?nm) are found to be 246.27 and 48.35?cm?1 at 1.8?THz, respectively. A detailed study suggests that the multiple resonance peaks in the absorption spectra are due to low frequency acoustic vibrational phonon modes of Fe3O4 nanostructures. Moreover, we demonstrate that the magnitude of total absorption can be tailored by varying the shell thickness of NHSs. It is found to increase with increasing shell thickness, and attain a maximum value of 498.5?cm?1 for the NHSs of average diameter 350?nm at 1.8?THz. The invariance of frequency dependent magnetic permeability points out that the absorption is basically due to dielectric loss instead of magnetic loss. The enhanced THz conductivity of Fe3O4 NHSs, as compared to NPs is described in light of thermally activated polaronic hopping which is found to increase with increasing THz absorption. Finally, the size dependent THz conductivity of NHSs confirms its sole dependence on the magnitude of THz absorptivity.

  16. Ab initio determination of geometries and vibrational characteristics of building blocks of organic superconductors: 4,5-Ethylenedithio-1,3-dithiole-2-thione, and 4,5-ethylenedithio-1,3-dithiole-2-one.

    PubMed

    Jaiswal, S; Singh, Deepshikha; Prasad, R L; Yadav, R A

    2010-08-01

    RHF and DFT calculations were carried out to study the optimized molecular geometries and vibrational characteristics of the 4,5-ethylenedithio-1,3-dithiole-2-thione (EDT-DTT) and 4,5-ethylenedithio-1,3-dithiole-2-one (EDT-DTO) molecules and their radical cations and anions. It is found that the anionic radical of the EDT-DTO molecule is unstable. Both the neutral molecules and their radical cations have non-planar structures with C(2) symmetry while the radical anion of the EDT-DTT molecule has non-planar structure with C(1) symmetry. It is found that the most of the vibrational characteristics of the radicals are similar to their corresponding neutral molecules, however, for some of the modes significant changes are noticed. As a result of anionic radicalization of EDT-DTT, the IR intensity and Raman activity increase and Raman band becomes polarized for both the CH(2) twisting modes. Drastic enhancements in the Raman activity and reduced IR intensity are noticed for the C=S/O stretching mode in going from neutral molecules to their radical ions consistent with charge separation along this bond. The C=S and C=C stretching wavenumber changes are consistent with corresponding bond length changes in going from neutral to their radical ions. PMID:20430691

  17. Helicopter rotor blade design for minimum vibration

    NASA Technical Reports Server (NTRS)

    Taylor, R. B.

    1984-01-01

    The importance of blade design parameters in rotor vibratory response and the design of a minimum vibration blade based upon this understanding are examined. Various design approaches are examined for a 4 bladed articulated rotor operating at a high speed flight condition. Blade modal shaping, frequency placement, structural and aerodynamic coupling, and intermodal cancellation are investigated to systematically identify and evaluate blade design parameters that influence blade airloads, blade modal response, hub loads, and fuselage vibration. The relative contributions of the various components of blade force excitation and response to the vibratory hub loads transmitted to the fuselage are determined in order to isolate primary candidates for vibration alleviation. A blade design is achieved which reduces the predicted fuselage vibration from the baseline blade by approximately one half. Blade designs are developed that offer significant reductions in vibration (and fatigue stresses) without resorting to special vibration alleviation devices, radical blade geometries, or weight penalties.

  18. The Power Generation Characteristics and Durability of a Vibration Power Generation Device using Piezoelectric Thick Film Formed Directly by Screen Printing on a Stainless Steel Substrate

    NASA Astrophysics Data System (ADS)

    Oishi, A.; Okumura, H.; Katsumura, H.; Kagata, H.

    2014-11-01

    This paper presents a small, high-performance and novel device that generates power from vibrations, made using screen-printing to form a piezoelectric thick film directly on a stainless steel substrate. This simple and cheap method realizes a 20 – 40 ?m-thick piezoelectric film, otherwise difficult to achieve using thin-film techniques or ceramic sintering, on a stainless steel substrate. A maximum output power of 1.1 mW was recorded with acceleration of 0.1 G0p (0.98 ms?2) applied at a resonance frequency of 24 Hz. We also evaluated the durability of the device by repeatedly striking the tip of the element. Output power exceeding 100 mW under damped resonant vibration was generated at the instant of striking, with approximately 0.9 mJ of power measured per single damped vibration. No deterioration was seen in the integrity of the stainless steel substrate or the piezoelectric thick film after over 10 million strikes.

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

    PubMed

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

    2014-06-01

    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

  20. Swelling and ketoprofen release characteristics of thermo- and pH-responsive copolymer gels.

    PubMed

    Negishi, M; Hiroki, A; Horikoshi, Y; Miyajima, M; Asano, M; Katakai, R; Yoshida, M

    1999-04-01

    Swelling-controlled drug delivery copolymer gels were newly synthesized by introducing thermo- and pH-responsive methacryloyl-glycine (MA-Gly) or pH-responsive methacrylic acid (MA-Ac) for comparison with thermoresponsive acryloyl-L-proline ethyl ester (A-ProOEt). A homopolymer gel of A-ProOEt was kept at degrees of swelling that were less than 0.5 at a pH from 2.5 to 7.5 at 37 degrees C. The thresholds of swelling for copolymer gels consisting of A-ProOEt/MA-Gly and A-ProOEt/MA-Ac with a composition of 40/60 mol% were found to be pH 3.0 and pH 5.5, respectively, in buffer solutions at 37 degrees C. The diffusion characteristics of 2-(3-benzoylphenyl)propionic acid (ketoprofen) from such copolymer gels was evaluated in buffer solutions at pH's more than 5.5, and it was found that A-ProOEt/MA-Gly gel possesses a case II transport mechanism that is completely linear time dependent in both the amount diffused and the penetrating swelling front position. On the other hand, A-ProOEt/MA-Ac gel exhibited a non-Fickian (or anomalous) diffusion behavior under the same conditions. PMID:10194598

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

    SciTech Connect

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

    2008-06-01

    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.

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

    PubMed

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

    2007-04-01

    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

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

    NASA Astrophysics Data System (ADS)

    Kumar, V. Raj; Kumar, M. B. Bharathi Raj; Kumar, M. Senthil

    2011-10-01

    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.

  4. Flow-induced vibration of component cooling water heat exchangers

    SciTech Connect

    Yeh, Y.S.; Chen, S.S. (Taiwan Power Co., Taipei (Taiwan). Nuclear Engineering Dept.; Argonne National Lab., IL (USA))

    1990-01-01

    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 heat exchangers are demonstrated, including energy-trapping modes, existence of tube-support-plate (TSP)-inactive modes, and fluidelastic instability of TSP-active and -inactive modes. On the basis of this evaluation, the difficulties and future research needs for the evaluation of heat exchangers are identified. 11 refs., 19 figs., 3 tabs.

  5. Ultrafast infrared spectroscopy of riboflavin: dynamics, electronic structure, and vibrational mode analysis.

    PubMed

    Wolf, Matthias M N; Schumann, Christian; Gross, Ruth; Domratcheva, Tatiana; Diller, Rolf

    2008-10-23

    Femtosecond time-resolved infrared spectroscopy was used to study the vibrational response of riboflavin in DMSO to photoexcitation at 387 nm. Vibrational cooling in the excited electronic state is observed and characterized by a time constant of 4.0 +/- 0.1 ps. Its characteristic pattern of negative and positive IR difference signals allows the identification and determination of excited-state vibrational frequencies of riboflavin in the spectral region between 1100 and 1740 cm (-1). Density functional theory (B3LYP), Hartree-Fock (HF) and configuration interaction singles (CIS) methods were employed to calculate the vibrational spectra of the electronic ground state and the first singlet excited pipi* state as well as respective electronic energies, structural parameters, electronic dipole moments and intrinsic force constants. The harmonic frequencies of the S 1 excited state calculated by the CIS method are in satisfactory agreement with the observed band positions. There is a clear correspondence between computed ground- and excited-state vibrations. Major changes upon photoexcitation include the loss of the double bond between the C4a and N5 atoms, reflected in a downshift of related vibrations in the spectral region from 1450 to 1720 cm (-1). Furthermore, the vibrational analysis reveals intra- and intermolecular hydrogen bonding of the riboflavin chromophore. PMID:18821792

  6. Theoretical study of the distal-side steric and electrostatic effects on the vibrational characteristics of the FeCO unit of the carbonylheme proteins and their models.

    PubMed Central

    Kushkuley, B; Stavrov, S S

    1996-01-01

    The vibronic theory of activation and quantum chemical intermediate neglect of differential overlap (INDO) calculations are used to study the activation of carbon monoxide (change of the C-O bond index and force field constant) by the imidazole complex with heme in dependence on the distortion of the porphyrin ring, geometry of the CO coordination, iron-carbon and iron-imidazole distances, iron displacement out of the porphyrin plane, and presence of the charged groups in the heme environment. It is shown that the main contribution to the CO activation stems from the change in the sigma donation from the 5 sigma CO orbital to iron, and back-bonding from the iron to the 2 pi orbital of CO. It follows from the results that none of the studied distortions can explain, by itself, the wide variation of the C-O vibrational frequency in the experimentally studied model compounds and heme proteins. To study the dependence of the properties of the FeCO unit on the presence of charged groups in the heme environment, the latter are simulated by the homogeneous electric field and point charges of different magnitude and location. The results show that charged groups can strongly affect the strength of the C-O bond and its vibrational frequency. It is found that the charges located on the distal side of the heme plane can affect the Fe-C and C-O bond indexes (and, consequently, the Fe-C and C-O vibrational frequencies), both in the same and in opposite directions, depending on their position. The theoretical results allow us to understand the peculiarities of the effect of charged groups on the properties of the FeCO unit both in heme proteins and in their model compounds. Images FIGURE 2 PMID:8785279

  7. Vibration and eigenvalue analysis using finite elements

    Microsoft Academic Search

    Tirupathi R. Chandrupatla; Ashok D. Belegundu

    1992-01-01

    The paper presents the steps involved in the use of finite elements for the analysis of vibration problems. Formation of stiffness and mass matrices is followed by discussion of techniques of reducing the size of the matrices. Characteristic polynomial, vector iteration, and transformation methods of eigenvalue and eigenvector evaluation for free vibrations of structures are presented. Damping aspects are discussed

  8. Special features of a digital speckle interferometer for determining vibration characteristics of heavy-loaded elements of an aircraft fuel pump

    Microsoft Academic Search

    O. A. Zhuravlev; E. V. Shakhmatov; A. N. Kryuchkov; N. D. Bystrov; A. I. Dolgov

    2009-01-01

    The results of vibration tests for heavy-loaded elements in the auger-centrifugal stage of an aircraft fuel pump performed\\u000a with the use of an interference-free digital speckle-interferometer created at the Samara State Aerospace University are presented.\\u000a The speckle-interferograms of an auger and a centrifugal wheel of the auger-centrifugal pump stage in different conditions\\u000a of attachment and dynamic loading are given. The

  9. Field measurements of boundary layer wind characteristics and wind-induced responses of super-tall buildings

    Microsoft Academic Search

    J. Y. Fu; Q. S. Li; J. R Wu; Y. Q. Xiao; L. L. Song

    2008-01-01

    This paper presents field measurement results of boundary layer wind characteristics over typical open country and urban terrains and wind-induced responses of two super-tall buildings during the passages of windstorms. The field data such as wind speed, wind direction and acceleration responses, etc., were measured from an observation tower with height of 17.5m at a coastal region in Lufeng and

  10. Dynamic characteristics and forced response of an electrostatically-actuated microbeam subjected to fluid loading

    Microsoft Academic Search

    Ghader Rezazadeh; Mohammad Fathalilou; Rasool Shabani; Saeid Tarverdilou; Soheil Talebian

    2009-01-01

    In this paper flexural vibrations of an electrostatically actuated cantilever microbeam in an incompressible inviscid stationary\\u000a fluid have been studied. By applying “Three dimensional aerodynamic theory” pressure jump across the microbeam has been investigated and the inertial effects of fluid on microbeam dynamics have been\\u000a modeled as a mass added to microbeam mass. Magnitude of the added mass has been

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

    PubMed

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

    2013-07-01

    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

  12. Negative differential resistance and characteristic nonlinear electromagnetic response of a Topological Insulator

    E-print Network

    Ching Hua Lee; Xiao Zhang; Bochen Guan

    2015-05-10

    Materials exhibiting negative differential resistance have important applications in technologies involving microwave generation, which range from motion sensing to radio astronomy. Despite their usefulness, there has been few physical mechanisms giving rise to materials with such properties, i.e. GaAs employed in the Gunn diode. In this work, we show that negative differential resistance also generically arise in Dirac ring systems, an example of which has been experimentally observed in the surface states of Topological Insulators. This novel realization of negative differential resistance is based on a completely different physical mechanism from that of the Gunn effect, relying on the characteristic non-monotonicity of the response curve that remains robust in the presence of nonzero temperature, chemical potential, mass gap and impurity scattering. As such, it opens up new possibilities for engineering applications, such as frequency upconversion devices which are highly sought for terahertz signal generation. Our results may be tested with thin films of Bi2Se3 Topological Insulators, and are expected to hold qualitatively even in the absence of a strictly linear Dirac dispersion, as will be the case in more generic samples of Bi2Se3 and other materials with topologically nontrivial Fermi sea regions.

  13. Analysis of response lag in hydraulic power steering system

    Microsoft Academic Search

    Shinji Nishimura; Tsugiharu Matsunaga

    2000-01-01

    Response lag during rapid steering in the hydraulic power steering system of a vehicle was analyzed with a numerical simulation mathematical model which considered the propagation of pressure waves in a hydraulic line and visco-elastic characteristics of the hose. Pressure perturbation by pump flow ripple and self-excited vibration which were incompatible with the response, were analyzed by the simulation. From

  14. Vibration imagery of remote objects

    NASA Astrophysics Data System (ADS)

    Ebert, Reinhard R.; Lutzmann, Peter

    2002-12-01

    Laser vibrometry based on coherent detection technique allows to measure vibration characteristics of objects, based on its high Doppler resolution. Point targets were measured up to 40 km under medium turbluence conditions. Specifically vibration imaging offers an extensive potential for short-range civil applications and for long-range target classification and identification. For short range applications (up to few meters distance) laser vibrometry is used for investigating and testing of all kind of mechanical structures with respect to their vibration characteristics. Laser-Doppler based acoustic-to-seismic detection of buried mines shows a potential of this attractive technique at short range, mostly based on ? = 632 nm (HeNe laser). At longer ranges, the wavelengths of ? = 10.6 ?m (CO2 laser) and ? = 1.5 ?m (erbium fiber laser) are of interest, because of laser safety and better beam propagation through the atmosphere. Examples of the vibrometry technique with and without spatial resolution capability are shown here.

  15. Defining Characteristics of Social Studies Teachers: A Response to Ochoa's Challenge.

    ERIC Educational Resources Information Center

    McMann, Francis Carroll, Jr.; McMann, Carolyn Jepsen

    1984-01-01

    Research undertaken at the University of Indiana to systematically identify the characteristics of social studies teachers is criticized and an alternative method for the future study of social studies teacher characteristics is presented. (RM)

  16. Vibration analysis of a large underwater shell of revolution

    SciTech Connect

    Yasuzawa, Y.; Kagawa, K. [Kyushu Univ., Fukuoka (Japan); Takahashi, H. [Ishikawajima-Harima Heavy Industry Co., Ltd., Tokyo (Japan)

    1995-12-31

    This is the 2nd report on structural feasibility study of an underwater half drop shaped shell , the 1st one was reported in ISOPE`93. Dynamic characteristics of a large underwater shell of revolution are studied in the paper. Large rotational shell having optimum shape with respect to the hydrostatic pressure can be used for a storage of LNG or vessel of super conducting coil for power storage in the future. In this study, which is one of many structural feasibility studies for the shell, vibration characteristics of the shell are examined using numerical analysis, in which finite elements for the structure and boundary elements for surrounding water are used. Natural frequencies and modes of an underwater drop shaped shell are examined using a developed numerical code DASOR. The code was justified by comparison with other results of vibration analysis of a submerged cylindrical shell for various water levels. The added mass effect of the underwater drop shaped shell in each vibration mode is discussed and the ratio of modal mass of structure in water and in air in the lowest mode proved to be very large specially for axisymmetrical mode and horizontal lowest mode. A seismic response analysis of the underwater shell of revolution with the excitation coming from a horizontally moving seabed is performed numerically and statistically. The analysis using power spectrum density function provide with the responses of distribution of displacements, membrane stresses, and bending moments.

  17. Determining Cutoff Scores on a Developmental Screening Measure: Use of Receiver Operating Characteristics and Item Response Theory

    Microsoft Academic Search

    Paul Yovanoff; Jane Squires

    2006-01-01

    Two different theoretical approaches were compared to determine the optimal cutoff scores for the Ages and Stages Questionnaires: Social-Emotional (ASQ: SE), a social-emotional screening test. Cutoff scores based on statistical decision theory modeling, Receiver Operator Characteristics (ROC), were compared with cutoff scores obtained using Item Response Theory (IRT) measurement theory modeling. The purposes of this comparison were (a) to offer

  18. Vibration-based damage identification and health monitoring of civil structures

    E-print Network

    He, Xianfei

    2008-01-01

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

  19. Coupled rotor/airframe vibration analysis

    NASA Technical Reports Server (NTRS)

    Sopher, R.; Studwell, R. E.; Cassarino, S.; Kottapalli, S. B. R.

    1982-01-01

    A coupled rotor/airframe vibration analysis developed as a design tool for predicting helicopter vibrations and a research tool to quantify the effects of structural properties, aerodynamic interactions, and vibration reduction devices on vehicle vibration levels is described. The analysis consists of a base program utilizing an impedance matching technique to represent the coupled rotor/airframe dynamics of the system supported by inputs from several external programs supplying sophisticated rotor and airframe aerodynamic and structural dynamic representation. The theoretical background, computer program capabilities and limited correlation results are presented in this report. Correlation results using scale model wind tunnel results show that the analysis can adequately predict trends of vibration variations with airspeed and higher harmonic control effects. Predictions of absolute values of vibration levels were found to be very sensitive to modal characteristics and results were not representative of measured values.

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

    PubMed

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

    2012-05-01

    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

  1. The effects of experimenter characteristics and two stressors on the hemodynamic responsivity of young normotensive adults

    Microsoft Academic Search

    Paige Alison Green

    1994-01-01

    Cardiovascular reactivity paradigms are used to examine race and gender differences in cardiovascular regulation. The purposes of the present study were to determine if: (1) race and gender differences in responsivity to laboratory challenge emerge; (2) different hemodynamic patterns underlie the hypothesized group differences in responsivity; and (3) differences in experimenter race and gender influence responsivity. Using impedance cardiography, responsivity

  2. [Discrimination and spectral response characteristic of stress leaves infected by rice Aphelenchoides besseyi Christie].

    PubMed

    Liu, Zhan-Yu; Shi, Jing-Jing; Wang, Da-Cheng; Huang, Jing-Feng

    2010-03-01

    An ASD Field Spec Pro Full Range spectrometer was used to acquire the spectral reflectance of healthy and diseased leaves infected by rice Aphelenchoides besseyi Christie, which were cut from rice individuals in the paddy field. Firstly, foliar pigment content was investigated. As compared with healthy leaves, the total chlorophyll and carotene contents (mg x g(-1)) of diseased leaves decreased 18% and 22%, respectively. The diseased foliar content ratio of total chlorophyll to carotene was nearly 82% of the healthy ones. Secondly, the response characteristics of hyperspectral reflectance of diseased leaves were analyzed. The spectral reflectance in the blue (450-520 nm), green (520-590 nm) and red (630-690 nm) regions were 2.5, 2 and 3.3 times the healthy ones respectively due to the decrease in foliar pigment content, whereas in the near infrared (NIR, 770-890 nm) region was 71.7 of the healthy ones because of leaf twist, and 73.7% for shortwave infrared (SWIR, 1 500-2 400 nm) region, owing to water loss. Moreover, the hyperspectral feature parameters derived from the raw spectra and the first derivative spectra were analyzed. The red edge position (REP) and blue edge position (BEP) shifted about 8 and 10 nm toward the short wavelengths respectively. The green peak position (GPP) and red trough position (RTP) shifted about 8.5 and 6 nm respectively toward the longer wavelengths. Finally, the area of the red edge peak (the sum of derivative spectra from 680 to 740 nm) and red edge position (REP) as the input vectors entered into C-SVC, which was an soft nonlinear margin classification method of support vector machine, to recognize the healthy and diseased leaves. The kernel function was radial basis function (RBF) and the value of punishment coefficient (C) was obtained from the classification model of training data sets (n = 138). The performance of C-SVC was examined with the testing sample (n = 126), and healthy and diseased leaves could be successfully differentiated without errors. This research demonstrated that the response feature of spectral reflectance was obvious to disease stress in rice leaves, and it was feasible to discriminate diseased leaves from healthy ones based on C-SVC model and hyperspectral reflectance. PMID:20496693

  3. Simulated and measured dose response characteristics of detectors used for CT dosimetry.

    PubMed

    Hakanen, Arvi

    2012-08-21

    A CT-SD16 semiconductor detector was calibrated in terms of the computed tomography (CT) air kerma index for the integration length L = 100 mm, C(K,PMMA,100), in the cylindrical CT head and body dosimetry phantoms using a DCT10 pencil ionization chamber as a reference instrument. Using IEC RQT 9 120-kV x-ray radiation quality and 25-62.5 mm nominal beam widths free in air, a C(K,PMMA,100)(DCT10)/C(K,PMMA,100)(CT-SD16) ratio of 0.97 was observed, while in the centre of 300 mm long CT head and body dosimetry phantoms, C(K,PMMA,100)(DCT10)/C(K,PMMA,100)(CT-SD16) ratios ranged from 1.02 to 1.09. Using IEC RQT 8-10 radiation qualities free in air, Monte Carlo simulated dose response characteristics of CT-SD16 and DCT10 were comparable with those obtained from the measurements. Simulations were also used to determine C(K,PMMA,100)(DCT10) in the centre of the CT head and body phantoms. At IEC RQT 9 and 25-62.5 mm nominal beam widths, the relative values of the simulated dose agreed with the measured values within 2-10% for the head and body phantoms, respectively. A k(q) correction factor between dose measurements in the phantom and free in air was determined for the model of DCT10 and for the real detectors using measured C(K,PMMA,100) data. Simulations were performed using the EGSnrc CAVRZ code. PMID:22850226

  4. Mast cells of the bovine trachea: staining characteristics, dispersion techniques and response to secretagogues.

    PubMed Central

    Harris, W H; Marshall, J S; Yamashiro, S; Shaikh, N

    1999-01-01

    Sections of the lower trachea of cattle, fixed in either Carnoy's or formalin, were stained with toluidine blue, alcian blue, or alcian blue and safranin O to study the mast cell population. After toluidine blue staining, about twice as many cells in tissue fixed in Carnoy's contained dark blue granules compared with tissue fixed in formalin. In addition, for the first time in cattle, a population of cells containing red granules was identified after staining with alcian blue and safranin O. Most of these red granules were formalin sensitive. An enzymatic dispersal technique for mast cells is described that yielded 9.4+/-0.4% mast cells (percentage of nucleated cells) with a viability of 92.3+/-0.6%. Spontaneous histamine release was 3.3+/-0.8%. Dispersed mast cells were challenged with various immunological and nonimmunological secretagogues. The calcium ionophores, A23187, ionomyocin, and BrX537A, were effective in releasing up to 94% of histamine in mast cells in a dose-response relationship. Pasteurella haemolytica culture supernate caused about 10% histamine release at a dose of 0.5 mg/mL after correction for spontaneous release. The average histamine content of the mast cells was 6.6+/-1.0 pg/cell. Cytospins of dispersed cells fixed in Carnoy's and stained with alcian blue and safranin O contained mast cells with blue and red granules, and a few cells with a mixture of both granule types. Based on the effects of type of fixation, staining characteristics and histamine content, a mix of subtypes of mast cells is present in the bovine trachea. However, functionally they respond to secretagogues differently than rodent mast cells. Without an immunological secretagogue, studies to determine compounds that will be effective in blocking mast cell degranulation will be limited. Images Figure 2. PMID:9918327

  5. Prediction of vehicle discomfort from transient vibrations

    Microsoft Academic Search

    P. Jönsson; Ö. Johansson

    2005-01-01

    Vehicle manufacturers are continuously seeking to improve vibration comfort. In this paper, subjective responses from transient vibrations in a forklift were analyzed on the basis of ISO 2631-1 and a number of additional variables. The objectives were to define: the effect of different operating conditions and appropriate background variables of subjects on perceived motions; the development of model that describes

  6. Whiplash evokes descending muscle recruitment and sympathetic responses characteristic of startle

    PubMed Central

    Mang, Daniel WH; Siegmund, Gunter P; Blouin, Jean-Sébastien

    2014-01-01

    Whiplash injuries are the most common injuries following rear-end collisions. During a rear-end collision, the human muscle response consists of both a postural and a startle response that may exacerbate injury. However, most previous studies only assessed the presence of startle using data collected from the neck muscles and head/neck kinematics. The startle response also evokes a descending pattern of muscle recruitment and changes in autonomic activity. Here we examined the recruitment of axial and appendicular muscles along with autonomic responses to confirm whether these other features of a startle response were present during the first exposure to a whiplash perturbation. Ten subjects experienced a single whiplash perturbation while recording electromyography, electrocardiogram, and electrodermal responses. All subjects exhibited a descending pattern of muscle recruitment, and increasing heart rate and electrodermal responses following the collision. Our results provide further support that the startle response is a component of the response to whiplash collisions. PMID:24932015

  7. Concorde noise-induced building vibrations, Sully Plantation - Report no. 2, Chantilly, Virginia

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Noise-induced building vibrations associated with Concorde operations were studied. The approach is to record the levels of induced vibrations and associated indoor/outdoor noise levels in selected homes, historic and other buildings near Dulles International Airport. Representative data are presented which were recorded at Sully Plantation, Chantilly, Virginia during the periods of May 20 through May 28, 1976, and June 14 through June 17, 1976. Recorded data provide relationships between the vibration levels of windows, walls, floors, and the noise associated with Concorde operations, other aircraft, and nonaircraft events. The results presented are drawn from the combined May-June data base which is considerably larger than the May data base covered. The levels of window, wall and floor vibratory response resulting from Concorde operations are higher than the vibratory levels associated with conventional aircraft. Furthermore, the vibratory responses of the windows are considerably higher than those of the walls and floors. The window response is higher for aircraft than recorded nonaircraft events and exhibits a linear response relationship with the overall sound pressure level. For a given sound pressure level, the Concorde may cause more vibration than a conventional aircraft due to spectral or other differences. However, the responses associated with Concorde appear to be much more dependent upon sound pressure level than spectral or other characteristics of the noise.

  8. Prediction of vehicle discomfort from transient vibrations

    NASA Astrophysics Data System (ADS)

    Jönsson, P.; Johansson, Ö.

    2005-04-01

    Vehicle manufacturers are continuously seeking to improve vibration comfort. In this paper, subjective responses from transient vibrations in a forklift were analyzed on the basis of ISO 2631-1 and a number of additional variables. The objectives were to define: the effect of different operating conditions and appropriate background variables of subjects on perceived motions; the development of model that describes perceived discomfort as a function of measured vibrations; and important frequencies for prediction of vibration discomfort. The experiment was based on 12 different operating conditions defined by the variables: vehicle speed, obstacle height and load conditions. Eleven professional drivers participated and their responses of overall discomfort were defined by a vector sum of three perceived motions: shaking, for-aft and up-down motions. The evaluation method, maximum transient vibration value as defined in ISO 2631-1 was found to be adequate in predicting vibration discomfort during a four second transient vibration exposure. By analysis of narrow frequency band spectra of vibrations several explanations for the test results are discussed. The best results were obtained using a prediction model based on accelerations in {1}/{3}-octave bands of pitch vibrations.

  9. Individual behavioural characteristics in pigs—influences of group composition but no differences in cortisol responses

    Microsoft Academic Search

    E. van Erp-van der Kooij; A. H. Kuijpers; S. J. Dieleman; D. M. Blankenstein; M. J. M. Tielen

    2003-01-01

    To determine the effect of group composition on backtest (Bt) responses and to determine the predictive value of the Bt for the physiological stress response to weaning and mixing, 814 pigs were backtested at 3, 10 and 17 days of age. Twenty-nine percent of all pigs were cross-fostered at 3 days according to Bt responses and groups were formed of

  10. Research of an Active Tunable Vibration Absorber for Helicopter Vibration Control

    Microsoft Academic Search

    Chen Yong; David G. Zimcik; Viresh K. Wickramasinghe; Fred Nitzsche

    2003-01-01

    Significant structural vibration is an undesirable characteristic in helicopter flight that leads to structural fatigue, poor ride quality for passengers and high acoustic signature. Previous Individual Blade Control (IBC) techniques to reduce these effects have been hindered by electromechanical limitations of piezoelectric actuators. The Smart Spring is an active tunable vibration absorber using IBC approach to adaptively alter the “structural

  11. Dynamic response characteristics of thermoelectric generator predicted by a three-dimensional heat-electricity coupled model

    NASA Astrophysics Data System (ADS)

    Meng, Jing-Hui; Zhang, Xin-Xin; Wang, Xiao-Dong

    2014-01-01

    The practical application environments of thermoelectric generators (TEGs) always change, which make a requirement for studying the dynamic response characteristics of TEGs. This work develops a complete, three-dimensional and transient model to investigate this issue. The model couples the energy and electric potential equations. Seebeck effect, Peltier effect, Thomson effect, Joule heating and Fourier heat conduction are taken into account in this model. Dynamic output power and conversion efficiency of the TEG, which are caused by variations of the hot end temperature, cold end temperature and load current, are studied. The response hysteresis of the output power to the hot end and cold end temperatures, the overshoot or undershoot of the conversion efficiency are found and attributed to the delay of thermal diffusion. However, the output power is synchronous with the load current due to much faster electric response than thermal response.

  12. Downhole vibration sensing by vibration energy harvesting

    E-print Network

    Trimble, A. Zachary

    2007-01-01

    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 ...

  13. Kinaesthetic role of muscle afferents in man, studied by tendon vibration and microneurography

    Microsoft Academic Search

    J. P. Roll; J. P. Vedel

    1982-01-01

    The characteristics of vibration-induced illusory joint movements were studied in healthy human subjects. Unseen by the subject, constant frequency vibration trains applied to the distal tendon of the Triceps or Biceps induced an almost constant velocity illusory movement of the elbow whose direction corresponded to that of a joint rotation stretching the vibrated muscle. Vibration trains of the same duration

  14. Study on the Application of H-Infinity Control to Double-Layer Vibration Isolation System

    Microsoft Academic Search

    Zeng Qianghong; Zhu Shijian; Luo Jingjun; Zhang Xin

    2010-01-01

    Double-layer vibration isolation device can significantly reduce the vibration of machinery and equipment delivered to the base or the environment. However, the passive approach is difficult to isolate the low-frequency vibration effectively. Active vibration isolation technology can set the control law according to the adjustment of dynamic characteristics parameters of the system, realize isolation requirements that passive isolation can not

  15. Welding characteristics of bi-metal, braided wires, aluminum and copper foils using 20 kHz ultrasonic complex vibration welding equipments

    Microsoft Academic Search

    Jiromaru Tsujino; Takashi Yokozuka; Shinnichiro Suga; Eiichi Sugimoto

    2010-01-01

    Welding characteristics of copper, bimetalic strip, braided flexible copper and tin coated copper wires consisted of thin wire elements, and large number of aluminum and copper thin foils are studied. Welding of copper, bimetal and braided wires and different metal foils are required for various electronic devices and multi-layer fuel cell, battery or EDLC electrodes for electric or hybrid automobile

  16. Stationary levitation and vibration transmission characteristic in a superconducting seismic isolation device with a permanent magnet system and a copper plate

    Microsoft Academic Search

    S. Sasaki; K. Shimada; T. Yagai; M. Tsuda; T. Hamajima; N. Kawai; K. Yasui

    2010-01-01

    We have devised a magnetic levitation type superconducting seismic isolation device taking advantage of the specific characteristic of HTS bulk that the HTS bulk returns to its original position by restoring force against a horizontal displacement. The superconducting seismic isolation device is composed of HTS bulks and permanent magnets (PM rails). The PMs are fixed on an iron plate to

  17. Hydrologic response of a semi-arid watershed to spatial and temporal characteristics of convective rain cells

    NASA Astrophysics Data System (ADS)

    Yakir, H.; Morin, E.

    2011-01-01

    Rain can be measured and represented in many ways such as point data from rain gauges, grid data from meteorological radar, or interpolated data. In this paper we represent rain fields by implementing a rain cell model of convective rain cells. The rain fields are used as an input to a hydrological model to test the watershed response to spatial and temporal characteristics of the rain cells. As a case study we tested an extreme storm event over a semi-arid watershed in southern Israel. The rain cell model was found to simulate the rain storm adequately. The use of these modeled cells allowed us to test the sensitivity of the watershed hydrological response to rain cell characteristics and it was found that the watershed is mainly sensitive to the starting location of the rain cell. Relatively small changes in the rain cell's location, speed and direction may increase watershed peak discharge by three-fold.

  18. Hydrologic response of a semi-arid watershed to spatial and temporal characteristics of convective rain cells

    NASA Astrophysics Data System (ADS)

    Yakir, H.; Morin, E.

    2010-10-01

    Rain can be measured and represented in many ways such as point data from rain gauges, grid data from meteorological radar, or interpolated data. In this paper we represent rain fields by implementing a rain cell model of convective rain cells. The rain fields are used as an input to a hydrological model to test the watershed response to spatial and temporal characteristics of the rain cells. As a case study we tested an extreme storm event over a semi-arid watershed in southern Israel. The rain cell model was found to simulate the rain storm adequately. The use of these modeled cells allowed us to test the sensitivity of the watershed hydrological response to rain cell characteristics and it was found that the watershed is mainly sensitive to the starting location of the rain cell. Relatively small changes in the rain cell's location, speed and direction may increase watershed peak discharge by three-fold.

  19. An analysis of the directional response characteristics of double tankers (i. e. , two articulated tank-trailers in Tandem)

    Microsoft Academic Search

    C. Millikarjunarao; P. Fancher

    1978-01-01

    An analysis of the directional response characteristics of double tankers (i.e., two articulated tank-trailers in Tandem), undertaken as part of a larger study by the University of Michigan, Highway Safety Research Institute for the Michigan State Office of Highway Safety Planning, indicated that the double-trailer gasoline tanker configuration corresponding to that used in Michigan has a lightly damped mode of

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

    NASA Astrophysics Data System (ADS)

    Aykan, Murat; Çelik, Mehmet

    2009-04-01

    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.

  1. Improving the characteristics of the modulation response for fiber Bragg grating Fabry-Perot lasers by optimizing model parameters

    NASA Astrophysics Data System (ADS)

    Hisham, H. K.; Abas, A. F.; Mahdiraji, G. A.; Mahdi, M. A.; Muhammad Noor, A. S.

    2012-09-01

    A unified and comprehensive study on the small-signal intensity and frequency modulation characteristics of a fiber Bragg grating Fabry-Perot (FBG-FP) laser are numerically investigated. The effect of injection current, temperature, external optical feedback (OFB), nonlinear gain compression factor, fiber grating (FG) parameters and spontaneous emission factor on modulation response characteristics are presented. The rate equations of the laser model are presented in the form that the effect of temperature (T) and external optical feedback (OFB) are included. The temperature dependence (TD) of laser response is calculated according to the TD of laser cavity parameters instead of directly using the well-known Parkove equation. It is shown that the optimum external fiber length (Lext) is 3.1 cm and the optimum range of working temperature for FGFP laser is within ±2 °C from the FBG reference temperature (To). Also, the antireflection (AR) coating reflectivity and the linewidth enhancement factor have no significant effect on the modulation spectra. It is also show that modulation response is extremely sensitive to the OFB level, high injection current and gain compression factor. The study indicates clearly that good dynamic characteristic can be obtained by system parameters optimization.

  2. Customized Message Generation and Speech Synthesis in Response to Characteristic Behavioral Patterns of Children

    Microsoft Academic Search

    Ho-joon Lee; Jong C. Park

    2007-01-01

    There is a growing need for a user-friendly human-computer interaction system that can respond to various characteristics\\u000a of a user in terms of behavioral patterns, mental state, and personalities. In this paper, we present a system that generates\\u000a appropriate natural language spoken messages with customization for user characteristics, taking into account the fact that\\u000a human behavioral patterns usually reveal one’s

  3. Nonlinear dynamics of a stack/cable system subjected to vortex-induced vibration

    SciTech Connect

    Cai, Y.; Chen, S.S. [Argonne National Lab., IL (United States). Energy Technology Div.

    1995-12-31

    A model of a stack/wire system, wind-induced vibration of the stack based on an unsteady-flow theory, and nonlinear dynamics of the stack`s heavy elastic suspended cables was developed in this study. The response characteristics of the stack and cables are presented for different conditions. The dominant excitation mechanisms are lock-in resonance of the stack by vortex shedding and parametric resonance of suspended cables by stack motion at their support ends.

  4. Nonlinear dynamics of a stack/cable system subjected to vortex-induced vibration

    SciTech Connect

    Cai, Y.; Chen, S.S. [Argonne National Lab., IL (United States). Energy Technology Div.

    1997-08-01

    A model of a stack/wire system, wind-induced vibration of the stack based on an unsteady-flow theory, and nonlinear dynamics of the stack`s heavy elastic suspended cables was developed in this study. The response characteristics of the stack and cables are presented for different conditions. The dominant excitation mechanisms are lock-in resonance of the stack by vortex shedding and parametric resonance of suspended cables by stack motion at their support ends.

  5. Cortisol response to stress in caregivers of offspring with autism spectrum disorder is associated with care recipient characteristics.

    PubMed

    de Andrés-García, Sara; Sariñana-González, Patricia; Romero-Martínez, Angel; Moya-Albiol, Luis; Gonzalez-Bono, Esperanza

    2013-09-01

    Providing care for people with autism spectrum disorder (ASD) is particularly stressful and frequently associated with disturbances in the hypothalamic-pituitary-adrenal (HPA) axis of the caregiver. This study examined whether the stress response is modulated by factors such as age of the care recipient and number of years spent by the caregiver in providing care for the ASD individual. Caregivers of children (n?=?15), adolescents (n?=?12), and adults (n?=?11) with ASD were exposed to two episodes of acute psychosocial stressor in a 1?day session. Salivary cortisol samples were obtained before, during, and after the stressor episodes. Psychological characteristics (states of anxiety, anger, and mood) were measured before and after the stressor episodes. The characteristics of the ASD individuals (age, degree of autism, global activity, and level of autonomy) were also registered. A difference in stress response was found when caregivers of ASD children were compared with those of ASD adolescents and adults, ??=?0.25, F(2.24,53.65)?=?5.82, p?response that correlated with the age of the patient (the older the patient, the lower the cortisol response). Additional factors, such as number of years spent providing care and level of autonomy of the recipient, also significantly contributed to the stress response. Together, the results demonstrate that recipient characteristics contribute to the detection of high-risk individuals within a caregiver population. PMID:23742094

  6. The influence of domain size on the response characteristics of a hurricane storm surge model

    Microsoft Academic Search

    C. A. Blain; J. J. Westerink; R. A. Luettich Jr

    1994-01-01

    The influence of domain size on boundary condition specification and on computed storm surge response is investigated. Storm surge response along the Florida shelf in the Gulf of Mexico due to Hurricane Kate is examined over three domains using two different open ocean boundary forcing functions, a still water (or zero elevation) condition and an inverted barometer condition which accounts

  7. Characteristics of indirect pharmacodynamic models and applications to clinical drug responses

    PubMed Central

    Sharma, Amarnath; Jusko, William J

    1998-01-01

    This review describes four basic physiologic indirect pharmacodynamic response (IDR) models which have been proposed to characterize the pharmacodynamics of drugs that act by indirect mechanisms such as inhibition or stimulation of the production or dissipation of factors controlling the measured effect. The principles underlying IDR models and their response patterns are described. The applicability of these basic IDR models to characterize pharmacodynamic responses of diverse drugs such as inhibition of gastric acid secretion by nizatidine and stimulation of MX protein synthesis by interferon ?-2a is demonstrated. A list of other uses of these models is provided. These models can be readily extended to accommodate additional complexities such as nonstationary or circadian baselines, equilibration delay, depletion or accumulation of a precursor pool, sigmoidicity, or other mechanisms. Indirect response models which have a logical mechanistic basis account for time-delays in many responses and are widely applicable in clinical pharmacology. PMID:9517366

  8. Response characteristics of pruriceptive and nociceptive trigeminoparabrachial tract neurons in the rat.

    PubMed

    Jansen, Nico A; Giesler, Glenn J

    2015-01-01

    We tested the possibility that the trigeminoparabrachial tract (VcPbT), a projection thought to be importantly involved in nociception, might also contribute to sensation of itch. In anesthetized rats, 47 antidromically identified VcPbT neurons with receptive fields involving the cheek were characterized for their responses to graded mechanical and thermal stimuli and intradermal injections of pruritogens (serotonin, chloroquine, and ?-alanine), partial pruritogens (histamine and capsaicin), and an algogen (mustard oil). All pruriceptive VcPbT neurons were responsive to mechanical stimuli, and more than half were additionally responsive to thermal stimuli. The majority of VcPbT neurons were activated by injections of serotonin, histamine, capsaicin, and/or mustard oil. A subset of neurons were inhibited by injection of chloroquine. The large majority of VcPbT neurons projected to the ipsilateral and/or contralateral external lateral parabrachial and Kölliker-Fuse nuclei, as evidenced by antidromic mapping techniques. Analyses of mean responses and spike-timing dynamics of VcPbT neurons suggested clear differences in firing rates between responses to noxious and pruritic stimuli. Comparisons between the present data and those previously obtained from trigeminothalamic tract (VcTT) neurons demonstrated several differences in responses to some pruritogens. For example, responses of VcPbT neurons to injection of serotonin often endured for nearly an hour and showed a delayed peak in discharge rate. In contrast, responses of VcTT neurons endured for roughly 20 min and no delayed peak of firing was noted. Thus the longer duration responses to 5-HT and the delay in peak firing of VcPbT neurons better matched behavioral responses to stimulation in awake rats than did those of VcTT neurons. The results indicate that VcPbT neurons may have important roles in the signaling of itch as well as pain. PMID:25298386

  9. Long transient phenomenon in nonlinear structural vibration

    NASA Astrophysics Data System (ADS)

    Frank Pai, P.

    2009-03-01

    The long transient phenomenon in nonlinear structural vibrations is examined in detail by using a signal decomposition and processing method based on the empirical mode decomposition, Hilbert-Huang transform (HHT), and nonlinear dynamic characteristics derived from perturbation analysis. A sliding-window fitting (SWF) technique is derived to show the physical implication of Hilbert-Huang transform and other time-frequency decomposition methods. The SWF uses windowed regular harmonics and function orthogonality to simultaneously extract time-localized regular and/or distorted harmonics. Because of the use of pre-determined basis functions, function orthogonality, and windowed curve fitting for component extraction, it cannot extract accurate time-varying frequencies and amplitudes of harmonics distorted by nonlinearities. On the other hand, the HHT uses the apparent time scales revealed by the signal's local maxima and minima to sequentially sift distorted harmonics of different time scales, starting from high-frequency to low-frequency ones. Because Hilbert-Huang transform does not use predetermined basis functions and function orthogonality for component extraction, it provides more accurate signal decomposition and instant amplitudes and frequencies of extracted distorted harmonics. Numerical results show that the proposed HHT-based signal decomposition and processing method can accurately decompose nonlinear nonstationary signals and extract accurate intrawave amplitude and phase modulations, distorted harmonic response under a single-frequency harmonic excitation, and different types and orders of nonlinearities. Using this signal processing method, the long transient phenomenon in nonlinear vibrations is found to be caused by nonlinearities, coupling of transient and forced vibrations, and/or modal coupling of multiple modes.

  10. Three-dimensional solutions for the free vibrations and buckling of thermally stressed multilayered angle-ply composite plates

    SciTech Connect

    Noor, A.K.; Burton, W.S. (NASA, Langley Research Center, Hampton, VA (United States))

    1992-12-01

    Analytic three-dimensional elasticity solutions are developed for the free vibration and buckling of thermally stressed rectangular multilayered angle-ply anisotropic plates which are assumed to have an antisymmetric lamination with respect to the middle plane. Sensitivity derivatives are evaluated and used to investigate the sensitivity of the vibration and buckling responses to variations in the different lamination and material parameters of the plate. A Duhamel-Neumann-type constitutive model is used, and the material properties are assumed to be independent of temperature. Numerical results are presented, showing the effects of variations in the material characteristics and fiber orientation of different layers, as well as the effect of initial thermal deformation on the vibrational and buckling responses of the plate. 20 refs.

  11. Three-dimensional solutions for the free vibrations and buckling of thermally stressed multilayered angle-ply composite plates

    NASA Astrophysics Data System (ADS)

    Noor, Ahmed K.; Burton, W. S.

    1992-12-01

    Analytic three-dimensional elasticity solutions are developed for the free vibration and buckling of thermally stressed rectangular multilayered angle-ply anisotropic plates which are assumed to have an antisymmetric lamination with respect to the middle plane. Sensitivity derivatives are evaluated and used to investigate the sensitivity of the vibration and buckling responses to variations in the different lamination and material parameters of the plate. A Duhamel-Neumann-type constitutive model is used, and the material properties are assumed to be independent of temperature. Numerical results are presented, showing the effects of variations in the material characteristics and fiber orientation of different layers, as well as the effect of initial thermal deformation on the vibrational and buckling responses of the plate.

  12. Can shes resolve temporal characteristics of sounds? New insights using auditory brainstem responses

    E-print Network

    Ladich, Friedrich

    system of the oyster toad¢sh Opsanus tau. Court- ship sounds in closely related species of sun¢shes (Ger.E. Wysocki). Abbreviations: ABR, auditory brainstem response; BM, body mass; HL, hearing level; SL, standard

  13. Corporate Responsiveness to Community Stakeholders: Effects of Contextual and Organizational Characteristics

    E-print Network

    Lin, Xiaodong

    Corporate Responsiveness to Community Stakeholders: Effects of Contextual and Organizational by their Community Reinvestment Act (CRA) lending activities and their performance ratings by CRA examiners. The authors developed and tested eight hypotheses on the influence of contextual (community income, minority

  14. Optimal ossicular site for maximal vibration transmissions to coupled transducers.

    PubMed

    Chung, Juyong; Song, Won Joon; Sim, Jae Hoon; Kim, Wandoo; Oh, Seung-Ha

    2013-07-01

    Totally implantable middle-ear prosthetic devices, such as the Esteem system (Envoy Medical Corporation), detect vibrational motion of the middle-ear ossicles rather than acoustic stimulation to the eardrum. This eliminates the need for a subcutaneous microphone, which is susceptible to interference by ambient noises. Study of the vibrational characteristics of the human ossicles provides valuable information for determining the site of maximum ossicular motion that would be optimal for attachment of the sensor portion of the prosthesis. In this study, vibrational responses at seven locations on the middle-ear ossicles (i.e., the malleus head, 4 different points on the incus body, middle of the incus long process, tip of the incus long process) in human temporal bones (n = 6) were measured using a laser Doppler vibrometer. The measurements were repeated after separating the incudostapedial joint (ISJ). Measured displacement at each location was normalized with the sound pressure level near the tympanic membrane (TM) for representation in the form of a displacement transfer function (DTF). The normalized squared sum of the DTFs (NSSDTF) was then calculated as a measure of vibration motion through a specific frequency range at the considered sites. The relatively large NSSDTF was observed at the sites on the superior part of the malleus head (MH), on the lateral part of the incus body (IBL), and on the superior part of the incus body near the incudomalleal joint (IBS1) for the frequency ranges of 1-4 kHz and 1-9 kHz, regardless of the condition of the ISJ. This indicates that maximum vibrational motion of the middle-ear is deliverable to the piezoelectric transducer of totally implantable devices through these sites. This article is part of a special issue entitled "MEMRO 2012". PMID:23337694

  15. Nonlinear dynamics of shape memory alloy oscillators in tuning structural vibration frequencies

    E-print Network

    Melnik, Roderick

    Nonlinear dynamics of shape memory alloy oscillators in tuning structural vibration frequencies 2010 Accepted 8 September 2012 Available online 18 October 2012 Keywords: Vibration tuning Frequency and vibration tuning of various structures, seismic response mitigation, and others. In vibration tuning in many

  16. Employee Affective Responses to Organizational Stress: Moderating Effects of Job Characteristics.

    ERIC Educational Resources Information Center

    Abdel-Halim, Ahmed A.

    1978-01-01

    This study, in a manufacturing firm, examined the relative importance of three variables: role conflict, ambiguity, and overload, as sources of stress and dissatisfaction among managerial personnel, and the moderating effects of job enrichment characteristics. Results and implications for work design and stress management are discussed.…

  17. An Analysis of Accounting Exam Answers: An inductive case study of response characteristics

    Microsoft Academic Search

    Gail Ridley

    2007-01-01

    This paper reports upon an exploratory study that aimed to identify and benchmark characteristics to account for the failure of students in short essay-style answers in the final examination of a second year core accounting unit. The purpose of doing so was to develop a benchmark against which future examination outcomes could be compared, to identify any differences in the

  18. Cancer breakthrough pain characteristics and responses to treatment at a VA medical center

    Microsoft Academic Search

    Shirley S Hwang; Victor T Chang; Basil Kasimis

    2003-01-01

    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

  19. Diuretic response in patients with acute decompensated heart failure: characteristics and clinical outcome—an analysis from RELAX-AHF

    PubMed Central

    Voors, Adriaan A; Davison, Beth A; Teerlink, John R; Felker, G Michael; Cotter, Gad; Filippatos, Gerasimos; Greenberg, Barry H; Pang, Peter S; Levin, Bruce; Hua, Tsushung A; Severin, Thomas; Ponikowski, Piotr; Metra, Marco

    2014-01-01

    Aims We studied the characteristics and clinical outcome related to diuretic response and the effects of serelaxin in patients hospitalized for acute heart failure (AHF). Methods and results RELAX-AHF was a double-blind, placebo-controlled trial, enrolling 1161 patients admitted to hospital for AHF who were randomized to 48 h i.v infusions of placebo or serelaxin (30 µg/kg per day) within 16 h from presentation. Diuretic response was defined as ? weight kg/[(total i.v. dose)/40 mg] + [(total oral dose)/80 mg)] furosemide (or equivalent loop diuretic dose) up to day 5. Median diuretic response was ?0.42 (?1.00, ?0.14) kg/40 mg. A poor diuretic response was independently associated with Western-like region (Western Europe, North America, Israel, and Poland), lower diastolic blood pressure, the absence of oedema, higher blood urea nitrogen, and lower levels of aspartate aminotransferase and potassium (all P < 0.01). Randomization to serelaxin was associated with lower doses of i.v. loop diuretics and slightly less weight loss, resulting in a neutral effect on diuretic response. Worse diuretic response was independently associated both with less relief of dyspnoea, measured with a visual analogue scale (VAS) at day 5 (primary endpoint; P = 0.0002), and with a higher risk of cardiovascular death or rehospitalization for heart failure or renal failure through day 60 (secondary endpoint, P < 0.0001), but not with increased 180-day cardiovascular mortality (P = 0.507). Conclusions In patients hospitalized for AHF, a poor diuretic response was associated with a poor in-hospital and early post-discharge clinical outcome. Serelaxin had a neutral effect on diuretic response. Trial registration: NCT00520806 PMID:25287144

  20. Thermal Response and Stability Characteristics of Bistable Composite Laminates by Considering Temperature Dependent Material Properties and Resin Layers

    NASA Astrophysics Data System (ADS)

    Moore, M.; Ziaei-Rad, S.; Salehi, H.

    2013-02-01

    In this study, the stability characteristics and thermal response of a bistable composite plate with different asymmetric composition were considered. The non-linear finite element method (FEM) was utilized to determine the response of the laminate. Attention was focused on the temperature dependency of laminate mechanical properties, especially on the thermal expansion coefficients of the composite graphite-epoxy plate. Also the effect of including the resin layers on the stability characteristics of the laminate was investigated. The effect of the temperature on the laminate cured configurations in the range of 25°C to 180°C and -60°C to 40°C was examined. The results indicate that the coefficient of thermal expansions has a major effect on the cured shapes. Next, optical microscopy was used to characterize the laminate composition and for the first time the effect of including the resin layers on the actuation loads that causes snapping behavior between two stable shapes was studied. The results obtained from the finite element simulations were compared with experimental results and a good correlation was obtained. Finally, the stability characteristics of a tapered composite panel were investigated for using in a sample winglet as a candidate application of bistable structures.

  1. Experimental and analytical investigations of fuselage modal characteristics and structural-acoustic coupling

    Microsoft Academic Search

    Myles A. Simpson; Gopal P. Mathur

    1992-01-01

    Measurements conducted on a DC-9 aircraft test section to define the shell and cavity modes of the fuselage, understand its structural-acoustic coupling characteristics, and measure its response to different types of acoustic and vibration excitations are reported. The data were processed to generate spatial plots and wavenumber maps of the shell acceleration and cabin acoustic pressure field. Analysis and interpretation

  2. 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

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

    2014-01-01

    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. PMID:25452873

  3. Development of monofilar rotor hub vibration absorber

    NASA Technical Reports Server (NTRS)

    Duh, J.; Miao, W.

    1983-01-01

    A design and ground test program was conducted to study the performance of the monofilar absorber for vibration reduction on a four-bladed helicopter. A monofilar is a centrifugal tuned two degree-of-freedom rotor hub absorber that provides force attenuation at two frequencies using the same dynamic mass. Linear and non-linear analyses of the coupled monofilar/airframe system were developed to study tuning and attenuation characteristics. Based on the analysis, a design was fabricated and impact bench tests verified the calculated non-rotating natural frequencies and mode shapes. Performance characteristics were measured using a rotating absorber test facility. These tests showed significant attenuation of fixed-system 4P hub motions due to 3P inplane rotating-system hub forces. In addition, detuning effects of the 3P monofilar modal response were small due to the nonlinearities and tuning pin slippage. However, attenuation of 4P hub motions due to 5P inplane hub forces was poor. The performance of the 5P monofilar modal response was degraded by torsional motion of the dynamic mass relative to the support arm which resulted in binding of the dynamic components. Analytical design studies were performed to evaluate this torsional motion problem. An alternative design is proposed which may alleviate the torsional motion of the dynamic mass.

  4. The dynamic-response characteristics of a 35 degree swept-wing airplane as determined from flight measurements

    NASA Technical Reports Server (NTRS)

    Triplett, William C; Brown, Stuart C; Smith, G Allan

    1955-01-01

    The longitudinal and lateral-directional dynamic-response characteristics of a 35 degree swept-wing fighter-type airplane determined from flight measurements are presented and compared with predictions based on theoretical studies and wind-tunnel data. Flights were made at an altitude of 35,000 feet covering the Mach number range of 0.50 to 1.04. A limited amount of lateral-directional data were also obtained at 10,000 feet. The flight consisted essentially of recording transient responses to pilot-applied pulsed motions of each of the three primary control surfaces. These transient data were converted into frequency-response form by means of the Fourier transformation and compared with predicted responses calculated from the basic equations. Experimentally determined transfer functions were used for the evaluation of the stability derivatives that have the greatest effect on the dynamic response of the airplane. The values of these derivatives, in most cases, agreed favorably with predictions over the Mach number range of the test.

  5. Vibration modeling and supression in tennis racquets.

    SciTech Connect

    Farrar, C. R. (Charles R.); Buechler, M. A. (Miles A.); Espino, Luis; Thompson, G. A. (Gordon A.)

    2003-01-01

    The size of the 'sweet spot' is one measure of tennis racquet performance. In terms of vibration, the sweet spot is determined by the placement of nodal lines across the racquet head. In this studx the vibrational characteristics of a tennis racquet are explorod to discover the size and location of the sweet spot. A numerical model of the racquet is developed using finite element analysis and the model is verified using the results from an experimental modal analysis. The affects of string tension on the racquet's sweet spot and mode shapes are then quantified. An investigation is also carried out to determine how add-on vibrational datnpers affect the sweet spot.

  6. Energy harvesting vibration sources for microsystems applications

    Microsoft Academic Search

    S P Beeby; M J Tudor; N M White

    2006-01-01

    This paper reviews the state-of-the art in vibration energy harvesting for wireless, self-powered microsystems. Vibration-powered generators are typically, although not exclusively, inertial spring and mass systems. The characteristic equations for inertial-based generators are presented, along with the specific damping equations that relate to the three main transduction mechanisms employed to extract energy from the system. These transduction mechanisms are: piezoelectric,

  7. Nonstationarities in Catchment Response According to Basin and Rainfall Characteristics: Application to Korean Watershed

    NASA Astrophysics Data System (ADS)

    Kwon, Hyun-Han; Kim, Jin-Guk; Jung, Il-Won

    2015-04-01

    It must be acknowledged that application of rainfall-runoff models to simulate rainfall-runoff processes are successful in gauged watershed. However, there still remain some issues that will need to be further discussed. In particular, the quantitive representation of nonstationarity issue in basin response (e.g. concentration time, storage coefficient and roughness) along with ungauged watershed needs to be studied. In this regard, this study aims to investigate nonstationarity in basin response so as to potentially provide useful information in simulating runoff processes in ungauged watershed. For this purpose, HEC-1 rainfall-runoff model was mainly utilized. In addition, this study combined HEC-1 model with Bayesian statistical model to estimate uncertainty of the parameters which is called Bayesian HEC-1 (BHEC-1). The proposed rainfall-runofall model is applied to various catchments along with various rainfall patterns to understand nonstationarities in catchment response. Further discussion about the nonstationarity in catchment response and possible regionalization of the parameters for ungauged watershed are discussed. KEYWORDS: Nonstationary, Catchment response, Uncertainty, Bayesian Acknowledgement This research was supported by a Grant (13SCIPA01) from Smart Civil Infrastructure Research Program funded by the Ministry of Land, Infrastructure and Transport (MOLIT) of Korea government and the Korea Agency for Infrastructure Technology Advancement (KAIA).

  8. Time response characteristics of an oxide-confined GaAs /AlGaAs resonant cavity-enhanced photodetector

    NASA Astrophysics Data System (ADS)

    Estacio, E.; Alonzo, C.; Samson, A.; Garcia, A.; Somintac, A.; Salvador, A.

    2004-10-01

    This work compares the speed characteristics of a ˜135-?m-diam GaAs /AlGaAs resonant cavity-enhanced (RCE) detector-emitter device with its laterally oxidized ˜80-?m-diam counterpart. The full width at half-maximum of the photocurrent spectrum exhibited no degradation in wavelength selectivity. Moreover, oxide confinement caused no current bottleneck that was inferred to adversely affect the device speed. The measured pulse responses were 65 and 75ps for the unoxidized and oxidized devices, respectively. Oxide-confined RCE photodetectors show relevant application in concentric hybrid RCE vertical cavity laser devices, this work deals with the speed characteristics of laterally oxidized resonant cavity-enhanced devices.

  9. Control and Response Characteristics of a Magneto-Rheological Fluid Damper for Passenger Vehicles

    Microsoft Academic Search

    Hwan-Soo Lee; Seung-Bok Choi

    2000-01-01

    This paper presents control characteristics of a full-car suspension featuring a semi-active magnetorheological (MR) fluid damper. A cylindrical MR damper is devised and its field-dependent damping force is evaluated with respect to the piston velocity. After verifying that the damping force can be continuously controlled by the intensity of the magnetic field, the MR damper is applied to a full-car

  10. Response Characteristics of Plant Bioelectric Potential to Light Intensity Indoor and Outdoor

    NASA Astrophysics Data System (ADS)

    Shimbo, Tatsuya; Fujii, Masaki; Sawada, Ayako; Oyabu, Takashi; Kimura, Haruhiko

    Plant is affected by environmental factors. For example, these are temperature, humidity and light intensity. The light intensity affected strongly to the plant. The plant produces glucose and oxygen with photosynthesis. Moreover, light intensity is important to purify the contaminants in the atmosphere. In this study, it was examined whether the plant is affected by temperature, wind grade and soil moisture using bioelectric potential characteristics of the plant. Especially plant bioelectric potential to light intensity change was measured. The measurement was carried out in indoor and outdoor. As for the result, the differences of plant bioelectric potential characteristics in the indoor and outdoor were recognized. At that analysis, the integrated value of plant bioelectric potential for 1 minute (vm1) was adopted. Moreover, a high correlation was indicated between the vm1 and light intensity. The correlation coefficient was R2=0.94. It becomes obvious that the plant is affected strongly by light intensity and the plant can understand the environmental factors like light intensity. The characteristics are found by measuring bioelectric potential of the plant. The environmental sensing can be possible by the use of the plant bioelectric potential.

  11. Auditory brainstem responses to airborne sounds in the aquatic frog Xenopus laevis : correlation with middle ear characteristics

    Microsoft Academic Search

    Bharti Katbamna; John A. Brown; Melissa Collard; Charles F. Ide

    2006-01-01

    In this study we recorded auditory brainstem responses to airborne sounds to determine the hearing sensitivity of Xenopus laevis frogs and correlated their hearing profiles with middle ear characteristics. In newly metamorphosed frogs (body mass 0.5–0.76 gm,\\u000a snout-vent length 17–20 mm) best hearing sensitivities were measured in the 2.4–2.8 kHz range, whereas optimal hearing sensitivity\\u000a of older adults (body mass 18–90 gm; snout-vent length

  12. Vibrational spectrum of buspirone

    NASA Astrophysics Data System (ADS)

    Cybulski, Jacek; Chilmonczyk, Zdzis?aw; Glice, Magdalena; Cybulski, Marcin; Bajdor, Krzysztof; Le?, Andrzej

    1997-02-01

    The IR and Raman spectra of buspirone and buspirone hydrochloride were recorded in KBr pellets and chloroform solutions. Most of the vibrational bands were assigned to normal modes using quantum mechanical semiempirical and ab initio restricted Hartree-Fock (RHF) calculations on model systems. The essential spectral characteristics can be obtained from the analysis of three building blocks of buspirone, i.e. pyrimidine-piperazine, butyl spacer and imide residues. The spectral regions particularly sensitive to intermolecular interactions were identified. The theoretical calculations suggest that the "NH +" band in buspirone hydrochloride reflects the formation of a moderately strong hydrogen bond between the protonated piperazine nitrogen atom (bound to the butyl spacer) and the chlorine anion.

  13. Light response characteristics of net CO 2 exchange in brackish wetland plant communities

    Microsoft Academic Search

    Bert G. Drake

    1984-01-01

    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

  14. Processing load during listening: The influence of task characteristics on the pupil response

    Microsoft Academic Search

    Sophia E. Kramer; Artur Lorens; Frans Coninx; Adriana A. Zekveld; Anna Piotrowska; Henryk Skarzynski

    2012-01-01

    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

  15. Tone-transfer (OECF) characteristics and spatial frequency response measurements for digital cameras and scanners

    Microsoft Academic Search

    Peter D. Burns

    2004-01-01

    Measurement of the spatial frequency response (SFR) of digital still cameras by slanted-edge analysis has been established for several years. The method, described in standard ISO 12233, has also been applied to other image acquisition subsystems such as document and print scanners. With the frequent application of the method and use of supporting software, questions often arise about the form

  16. Stomatal response characteristics of Tradescantia virginiana grown at high relative air humidity

    Microsoft Academic Search

    Abdolhossein Rezaei Nejad; Uulke van Meeteren

    2005-01-01

    Plants produced at high relative air humidity (RH) show poor control of water loss after transferring to low RH, a phenomenon which is thought to be due to their stomatal behaviour. The stomatal anatomy and responses of moderate (55%) and high (90%) RH grown Tradescantia virginiana plants to treatments that normally induce stomatal closure, i.e. desiccation, abscisic acid (ABA) application

  17. "Can't Nobody Sleep" and Other Characteristics of Culturally Responsive English Instruction

    ERIC Educational Resources Information Center

    Adkins, Theresa A.

    2012-01-01

    In this article the author presents a collective case study of two English teachers identified as particularly successful with Black students. Through the use of ethnographic techniques, the study provides a snapshot of how these teachers facilitated academic gains in urban high schools through their use of culturally responsive English…

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

    NASA Astrophysics Data System (ADS)

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

    2011-06-01

    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.

  19. Vibrational directionality in the southern green stink bug, Nezara viridula (L.), is mediated by female song.

    PubMed

    Cokl; Virant-Doberlet; McDowell

    1999-12-01

    We tested the hypothesis that male southern green stink bugs, Nezara viridula (L.), use substrate-borne songs to locate females. We recorded the responses of bugs on plants to the vibrations caused by a prerecorded female song and by an artificial sound. The female song caused males to walk, to respond with the calling and courtship songs and to approach the source of the song with characteristic search behaviour at junctions between branches on the plants. At a junction, a searching male stopped, stretched his legs and antennae and compared the vibratory signals on the two branches, with different combinations of legs and antennae. The males then left the junction and approached the source of the vibration. Males located the loudspeaker significantly more frequently in the presence than in the absence of vibratory stimuli on cyperus, Cyperus alternifolius L., and beans, Phaseolus vulgaris L. Vibrational directionality was also elicited by artificial pure tones whose spectral and temporal parameters were similar to those of natural female song. Females showed no reaction to vibratory stimulation and no vibrational directionality. We discuss possible mechanisms underlying vibrational directionality in the light of expected signal changes during transmission through plants. Copyright 1999 The Association for the Study of Animal Behaviour. PMID:10600150

  20. NSLS II Vibration and Acoustic Criteria Vibration Experiment Hall

    E-print Network

    Ohta, Shigemi

    NSLS 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 vibration criteria. The vibration needs of the vast majority of research equipment available today would

  1. Response of soil bacteria to Hg(II) in relation to soil characteristics and cell location

    Microsoft Academic Search

    Lionel Ranjard; Agnès Richaume; Lucile Jocteur-Monrozier; Sylvie Nazaret

    1997-01-01

    The response of indigenous bacterial communities to the addition of inorganic mercury (50 ?M of Hg(II)) was compared over a 30 day period in four soils of contrasting properties. Hg(II) impact was estimated by following population dynamics of viable heterotrophic bacteria (VH) and mercury resistant bacteria (HgR) by indirect enumeration in unfractionated soil and in the inner and outer parts

  2. Monte Carlo calculation of the energy response characteristics of a RadFET radiation detector

    Microsoft Academic Search

    P. Belicev; V. Spasic Jokic; S. Mayer; M. Milosevic; R. Ilic; M. Pesic

    2010-01-01

    The Metal -Oxide Semiconductor Field-Effect-Transistor (MOSFET, RadFET) is frequently used as a sensor of ionizing radiation in nuclear-medicine, diagnostic-radiology, radiotherapy quality-assurance and in the nuclear and space industries. We focused our investigations on calculating the energy response of a p-type RadFET to low-energy photons in range from 12 keV to 2 MeV and on understanding the influence of uncertainties in

  3. Stress response effects on growth, carcass characteristics, and tenderness in Bonsmara-influenced steers

    E-print Network

    Falkenberg, Shollie Marie

    2006-08-16

    the style and format of Journal of Animal Science. 2 stressor) had higher feed to gain ratios, and exit velocity was negatively correlated with ribeye area. Vann et al. (2004) reported flighty cattle had lower USDA Quality and Yield grades and higher... central nervous system (CNS) is involved in the maintenance of internal homeostasis and participates in the organization of stress responses, some areas of the nervous system may have specific roles in these regulatory mechanisms. Stressful stimuli may...

  4. Ring shear characteristics of waste rock materials in response to drainage and shear velocity

    NASA Astrophysics Data System (ADS)

    Lee, Choonoh; Jeong, Sueng Won; Cho, Yong-Chan

    2015-04-01

    The ring shear characteristics of Imgi waste materials collected from an abandoned mine deposit, Busan Metropolitan city, were investigated to examine the slope stability and mobility of failed masses. A series of ring shear tests were carried out to investigate the shear stress characteristics of waste materials under different drainage, consolidation and shearing speed conditions. The tests are performed at the same normal stress (16 kPa), but different drainage (drained and undrained conditions) and shearing speed (0.01, 0.1, 1, 10, 100 mm/sec) conditions. From the test results, we found that a ring shear stress is dependent on the drainage and the shearing speed conditions at the same normal stress. The materials tested typically exhibited a strain softening behavior. However, at the same shearing speed (especially for V < 10 mm/sec), the shear stress under drained condition is slightly smaller than the shear stress under undrained condition. In particular, it increases with increasing shearing speed. Grain crushing is also dependent on the drainage condition. Under drained conditions, the grain crushing has been observed in the shearing zone from the shearing surface to the bottom (i.e., ? 3.5 cm), but under undrained condition it has been observed only at the shearing surface (i.e., ? 1 cm).

  5. Responses of herbaceous plants to urban air pollution: effects on growth, phenology and leaf surface characteristics.

    PubMed

    Honour, Sarah L; Bell, J Nigel B; Ashenden, Trevor W; Cape, J Neil; Power, Sally A

    2009-04-01

    Vehicle exhaust emissions are a dominant feature of urban environments and are widely believed to have detrimental effects on plants. The effects of diesel exhaust emissions on 12 herbaceous species were studied with respect to growth, flower development, leaf senescence and leaf surface wax characteristics. A diesel generator was used to produce concentrations of nitrogen oxides (NO(x)) representative of urban conditions, in solardome chambers. Annual mean NO(x) concentrations ranged from 77 nl l(-l) to 98 nl l(-1), with NO:NO(2) ratios of 1.4-2.2, providing a good experimental simulation of polluted roadside environments. Pollutant exposure resulted in species-specific changes in growth and phenology, with a consistent trend for accelerated senescence and delayed flowering. Leaf surface characteristics were also affected; contact angle measurements indicated changes in surface wax structure following pollutant exposure. The study demonstrated clearly the potential for realistic levels of vehicle exhaust pollution to have direct adverse effects on urban vegetation. PMID:19117655

  6. Antibody characteristics for a continuous response fiber optic immunosensor for theophylline.

    PubMed

    Hanbury, C M; Miller, W G; Harris, R B

    1996-01-01

    A self-contained fiber optic immunosensor was developed to measure continuously theophylline concentrations. The analytical signal was derived from the non-radiative energy transfer quench of fluorescence following binding of a fluorescence donor, B-phycoerythrin labeled theophylline, to an energy acceptor, Texas Red labeled antibody. Increases in free theophylline analyte concentrations resulted in a shift in antibody binding equilibrium between labeled and unlabeled theophylline that elicited a proportional increase in the fluorescence. The selection criteria for a monoclonal antibody as a molecular recognition element, and the optimization of labeling conditions to maximize the dynamic range and minimize sensor response time are described. Under one or more Texas Red labeling conditions, five antibody clones exhibited significant quenching when mixed with labeled analyte and also demonstrated 95% or greater reversible binding to labeled analyte. Two clones failed to exhibit fluorescence quenching when mixed with labeled analyte. The response time of the indicator chemistry system was dependent on the dissociation rate constant of the antibody. The equilibrium response time of intact sensors was limited by analyte diffusion across the containment membrane. PMID:8828164

  7. Response characteristics of vegetation and soil environment to permafrost degradation in the upstream regions of the Shule River Basin

    NASA Astrophysics Data System (ADS)

    Chen, Shengyun; Liu, Wenjie; Qin, Xiang; Liu, Yushuo; Zhang, Tongzuo; Chen, Kelong; Hu, Fengzu; Ren, Jiawen; Qin, Dahe

    2012-12-01

    Permafrost degradation exhibits striking and profound influences on the alpine ecosystem, and response characteristics of vegetation and soil environment to such degradation inevitably differ during the entire degraded periods. However, up to now, the related research is lacking in the Qinghai-Tibetan Plateau (QTP). For this reason, twenty ecological plots in the different types of permafrost zones were selected in the upstream regions of the Shule River Basin on the northeastern margin of the QTP. Vegetation characteristics (species diversity, community coverage and biomass etc) and topsoil environment (temperature (ST), water content (SW), mechanical composition (SMC), culturable microorganism (SCM), organic carbon (SOC) and total nitrogen (TN) contents and so on), as well as active layer thickness (ALT) were investigated in late July 2009 and 2010. A spatial-temporal shifts method (the spatial pattern that is represented by different types of permafrost shifting to the temporal series that stands for different stages of permafrost degradation) has been used to discuss response characteristics of vegetation and topsoil environment throughout the entire permafrost degradation. The results showed that (1) ST of 0-40 cm depth and ALT gradually increased from highly stable and stable permafrost (H-SP) to unstable permafrost (UP). SW increased initially and then decreased, and SOC content and the quantities of SCM at a depth of 0-20 cm first decreased and then increased, whereas TN content and SMC showed obscure trends throughout the stages of permafrost degradation with a stability decline from H-SP to extremely unstable permafrost (EUP); (2) further, species diversity, community coverage and biomass first increased and then decreased in the stages from H-SP to EUP; (3) in the alpine meadow ecosystem, SOC and TN contents increased initially and then decreased, soil sandy fractions gradually increased with stages of permafrost degradation from substable (SSP) to transitional (TP), and to UP. Meanwhile, SOC/TN storages increased in the former stage, while they decreased in the latter stage. This study indicated that the response characteristics of vegetation and soil environment varied throughout the entire permafrost degradation, and SW was the dominant ecological factor that limited vegetation distribution and growth. Therefore, SSP and TP phases could provide a favourable environment for plant growth, mainly contributing to high SW.

  8. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-08-31

    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.

  9. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-10-13

    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. The month of June, 2004 was primarily occupied with the writing of the Phase I Final Report, the sole deliverable of Phase I, which will be submitted in the next quarter. Redesign of the laboratory prototype and design of the downhole (Phase II) prototype was begun.

  10. Use of speckle for determining the response characteristics of Doppler imaging radars

    NASA Technical Reports Server (NTRS)

    Tilley, D. G.

    1986-01-01

    An optical model is developed for imaging optical radars such as the SAR on Seasat and the Shuttle Imaging Radar (SIR-B) by analyzing the Doppler shift of individual speckles in the image. The signal received at the spacecraft is treated in terms of a Fresnel-Kirchhoff integration over all backscattered radiation within a Huygen aperture at the earth. Account is taken of the movement of the spacecraft along the orbital path between emission and reception. The individual points are described by integration of the point source amplitude with a Green's function scattering kernel. Doppler data at each point furnishes the coordinates for visual representations. A Rayleigh-Poisson model of the surface scattering characteristics is used with Monte Carlo methods to generate simulations of Doppler radar speckle that compare well with Seasat SAR data SIR-B data.

  11. Response Characteristics of Soil Fractal Features to Different Land Uses in Typical Purple Soil Watershed

    PubMed Central

    Luo, Bang-lin; Chen, Xiao-yan; Ding, Lin-qiao; Huang, Yu-han; Zhou, Ji; Yang, Tian-tian

    2015-01-01

    As a fundamental characteristic of soil physical properties, the soil Particle Size Distribution (PSD) is important in the research on soil moisture migration, solution transformation, and soil erosion. In this research, the PSD characteristics with distinct methods in different land uses are analyzed. The results show that the upper bound of the volume domain of the clay domain ranges from 5.743?m to 5.749?m for all land-use types. For the silt domain of purple soil, the value ranges among 286.852~286.966 ?m. For all purple soil land-use types, the order of the volume domain fractal dimensions is DclayDsilt(U)>Dsand (U)>Dsand and Dsilt>Dsilt(U)>Dsand>Dsand(U), respectively. As it is compared with all Dvi, the Dsilt has the most significant correlativity to the soil texture and organic matter in different land uses of the typical purple soil watersheds. Therefore, Dsilt will be a potential indictor for evaluating the proportion of fine particles in the PSD, as well as a key measurement in soil quality and productivity studies. PMID:25856376

  12. Temperature dependent spectral response characteristic of III-V compound tandem cell

    Microsoft Academic Search

    Lei Liu; NuoFu Chen; Yu Wang; YiMing Bai; Min Cui; FuBao Gao

    2009-01-01

    The GaInP\\/GaAs\\/Ge triple-junction tandem cells with a conversion efficiency of 27.1% were fabricated using metalorganic chemical\\u000a vapor deposition (MOCVD) technique. Temperature dependence of the spectral response measurements of the GaInP\\/GaAs\\/Ge tandem\\u000a cell was performed by a quantum efficiency system at temperatures ranging from 25°C to 160°C. The red-shift phenomena of the\\u000a absorption limit for all subcells were observed with increasing

  13. Modulation response characteristics of optical injection-locked cascaded microring laser

    NASA Astrophysics Data System (ADS)

    Yu, Shaowei; Pei, Li; Liu, Chao; Wang, Yiqun; Weng, Sijun

    2014-09-01

    Modulation bandwidth and frequency chirping of the optical injection-locked (OIL) microring laser (MRL) in the cascaded configuration are investigated. The unidirectional operation of the MRL under strong injection allows simple and cost-saving monolithic integration of the OIL system on one chip as it does not need the use of isolators between the master and slave lasers. Two cascading schemes are discussed in detail by focusing on the tailorable modulation response. The chip-to-power ratio of the cascaded optical injection-locked configuration has decreased by up to two orders of magnitude, compared with the single optical injection-locked configuration.

  14. ROTATION-VIBRATION TETRAHEDRAL

    E-print Network

    Sadovskií, Dmitrií

    ANALYSIS OF ROTATION-VIBRATION RELATIVE EQUILIBRIA ON THE EXAMPLE OF A TETRAHEDRAL FOUR ATOM (RE) of a nonrigid molecule which vibrates about a well de#12;ned equilibrium con#12;guration and rotates as a whole. Our analysis uni#12;es the theory of rotational and vibrational RE. We rely

  15. Active Members Excite And Measure Vibrations In Trusses

    NASA Technical Reports Server (NTRS)

    Kuo, Chin-Po; Chen, Gun-Shing; Wada, Ben K.

    1993-01-01

    Report describes experimental study of use of active structural members to excite and measure vibrations as small as microns in truss structure. Part of continuing effort to develop active vibration-suppressing control system adapting itself to changing and/or partly unknown dynamical characteristics of truss structure in outer space. Some aspects of control concept and potential terrestrial applications described in "Two Techniques For Suppressing Vibrations In Structures" (NPO-17889).

  16. Different characteristics of reactive oxygen species production by human keratinocyte cell line cells in response to allergens and irritants.

    PubMed

    Kim, Dong Hyun; Byamba, Dashlkhumbe; Wu, Wen H; Kim, Tae-Gyun; Lee, Min-Geol

    2012-02-01

    Keratinocytes mount immune responses through the secretion of a variety of inflammatory cytokines, soluble proteins and reactive oxygen species (ROS). However, the role of ROS in keratinocytes in response to allergens and irritants has not yet been elucidated. In this study, we investigated the (i) ROS production; (ii) potential sites of ROS production; (iii) expression of cell surface molecules; (iv) secretion of cytokines; and (v) ROS-dependent protein carbonylation in chemical-treated human keratinocyte cell line (HaCaT) cells. Treatment of HaCaT cells with 2,4-dinitrochlorobenzene (DNCB) and benzalkonium chloride (BKC) increased ROS levels in a time- and dose-dependent manner, as determined with dichlorodihydrofluorescein diacetate (CM-H(2) DCFDA), without reducing cell viability. Potential sources of ROS production were evaluated with pretreatment of diphenylene iodonium (DPI), an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase; rotenone, an inhibitor of the mitochondrial electron transport chain complex or allopurinol, a xanthine oxidase inhibitor. The DNCB-induced ROS was related to both NADPH oxidase and mitochondrial electron transport chain complex. Conversely, BKC-induced ROS was related to NADPH oxidase only. Western blotting using an anti-DNP antibody revealed ROS-dependent protein carbonylation in response to DNCB but not BKC. Both DNCB and BKC increased the secretion of IL-1? from HaCaT cells; however, ROS production as well as other changes, except DNCB-induced secretion of IL-1?, was not inhibited by antioxidants. Although the role of ROS in keratinocytes in response to chemicals was inconclusive, our results suggest that the characteristics of ROS produced by keratinocytes in response to chemicals might differ. PMID:22141451

  17. Failure characteristics of the isolated distal radius in response to dynamic impact loading.

    PubMed

    Burkhart, Timothy A; Andrews, David M; Dunning, Cynthia E

    2012-06-01

    We examined the mechanical response of the distal radius pre-fracture and at fracture under dynamic impact loads. The distal third of eight human cadaveric radii were potted and placed in a custom designed pneumatic impact system. The distal intra-articular surface of the radius rested against a model scaphoid and lunate, simulating 45° of wrist extension. The scaphoid and lunate were attached to a load cell that in turn was attached to an impact plate. Impulsive impacts were applied at increasing energy levels, in 10?J increments, until fracture occurred. Three 45° stacked strain gauge rosettes were affixed along the length of the radius quantifying the bone strains. The mean (SD) fracture energy was 45.5 (16) J. The mean (SD) resultant impact reaction force (IRFr) at failure was 2,142 (1,229)?N, resulting in high compressive strains at the distal (2,718 (1,698)?µ?) and proximal radius (3,664 (1,890)?µ?). We successfully reproduced consistent fracture patterns in response to dynamic loads. The fracture energy and forces reported here are lower and the strains are higher than those previously reported and can likely be attributed to the controlled, incremental, dynamic nature of the applied loads. PMID:22083972

  18. Rotationally sampled wind characteristics and correlations with MOD-OA wind turbine response

    SciTech Connect

    George, R.L.; Connell, J.R.

    1984-09-01

    This report presents results of a comprehensive wind and wind turbine measurement program: the Clayton, New Mexico, vertical plane array/MOD-OA project. In this experiment, the turbulent wind was measured for a large array of fixed anemometers located two blade diameters upwind of a 200-kW horizontal-axis wind turbine (HAWT). Simultaneously, key wind turbine response parameters were also measured. The first of two major objectives of this experiment was to determine the turbulent wind, rotationally sampled to emulate the motion of the wind turbine blade, for the range of different wind speeds and stability classes actually experienced by the wind turbine. The second major objective was to correlate this rotationally sampled wind with the wind turbine blade stress and power, in order to assess the usefulness of the wind measurements for wind turbine loads testing a prediction. Time series of rotationally sampled winds and wind turbine blade bending moments and power were converted to frequency spectra using Fourier transform techniques. These spectra were used as the basis for both qualitative and quantitative comparisons among the various cases. A quantitative comparison between the rotationally sampled wind input and blade bending response was made, using the Fourier spectra to estimate the blade transfer function. These transfer functions were then used to calculate an approximate damping coefficient for the MOD-OA fiberglass blade.

  19. An Investigation of low beta triplet vibrational issues at Fermilab's Collider Detector

    SciTech Connect

    Michael W. McGee

    2004-06-08

    The vibrational aspects of recent disturbances at the low beta focusing quadrupoles, which caused proton beam loss at the Collider Detector at Fermilab (CDF), are discussed. Two low beta focusing quadrupoles are supported by a girder, which is extended over the CDF collision hall pit on each side. The low beta girder has a ledge mount support at an alcove's face and two Invar rods near the opposite end. Forced response measurements were taken on the low beta girder, where the power spectral density (PSD) function was used to obtain RMS displacement. The effects of local excitation due to operating equipment and near-field excitation due to ambient ground motion caused by local traffic are examined. The discussion explores dynamic response characteristics of the low beta quadrupoles and supporting girder using beam loss as the vibrational stability criteria. This paper also presents practical problem-solving approaches for similar accelerator components.

  20. Principal Trajectories of Forced Vibrations

    Microsoft Academic Search

    Valery Pilipchuk

    \\u000a As shown earlier by Zhuravlev (1992) that harmonically loaded linear conservative systems possess an alternative physically\\u000a reasonable basis, which is generally different from that associated with conventional principal coordinates. Briefly, such\\u000a a basis determines directions of harmonic loads along which the system response is equivalent to a single oscillator. The\\u000a corresponding definition (principal directions of forced vibrations) is loosing sense

  1. Does Spatial Variation in Soil Characteristics Affect Tree Transpiration Responses to Vapor Pressure Deficit?

    NASA Astrophysics Data System (ADS)

    Traver, E.; Ewers, B. E.; Loranty, M.; Mackay, D. S.

    2006-12-01

    Forest canopy transpiration (Ec) both depends on and influences the local and regional atmospheric conditions. Because soil is the source of water for Ec, the soil's chemical and physical properties are also likely to be drivers of transpiration. The objective of this study is to spatially quantify the relationship between the soil's chemical and physical characteristics and Ec across environmental gradients. The two study sites are in northern Wisconsin, in mixed hardwood forest. In one site, the environmental gradient runs from a dry upland dominated by aspen (Populus tremuloides) to a wetland dominated by alders (Alnus rugosa). The second site has little elevational variation, is well-drained, and is dominated by sugar maple (Acer saccharum) bisected by a swath of red pine (Pinus resinosa). Ec data have been collected over three summers on the same set of trees using Granier sensors, while the soil samples were collected in 2006 from the same plots as the measured trees. Both of the approximately 120 m x 120 m plots have been sampled in 10 m x 10 m subplots based on a 3/7 cyclic sampling scheme to maximize spatially explicit information with a minimum number of sampled points. Roughly 150 trees were measured in each plot. We have previously shown an inverse relationship between the spatial autocorrelation of Ec and vapor pressure deficit (D). We thus hypothesize that a significant amount of this relationship can be explained by soil properties. Preliminary analysis of soil data from a representative transect in the aspen site show that soil texture, carbon (C) content, and nitrogen (N) content change along the gradient. From the upland through the wetland, Ec declined significantly, and, while all the soils were a sandy loam, the sand content showed a decreasing trend, while the silt content increased nearly two-fold. Across the same (upland to wetland) gradient, the C:N ratio showed a slightly increasing trend, but the total percentage values of the two elements increased nearly 25 fold: from C of 0.884 and N of 0.060 to C of 22.34 and N of 1.283. We hypothesize that the maple site will show less variability in Ec because of its more uniform soil characteristics. Ongoing work of soil moisture release curves, bulk density, and root biomass will provide additional explanations of the spatial relationships between Ec and D. Our analytical approach, then, provides a first step in explaining the processes behind spatial patterns in transpiration.

  2. Dynamical instability in surface permeability characteristics of building sandstones in response to salt accumulation over time

    NASA Astrophysics Data System (ADS)

    McCabe, S.; McKinley, J. M.; Gomez-Heras, M.; Smith, B. J.

    2011-07-01

    This paper explores how the surface permeability of sandstone blocks changes over time in response to repeated salt weathering cycles. Surface permeability controls the amount of moisture and dissolved salt that can penetrate in and facilitate decay. Connected pores permit the movement of moisture (and hence soluble salts) into the stone interior, and where areas are more or less permeable soluble salts may migrate along preferred pathways at differential rates. Previous research has shown that salts can accumulate in the near-surface zone and lead to partial pore blocking which influences subsequent moisture ingress and causes rapid salt accumulation in the near-surface zone. Two parallel salt weathering simulations were carried out on blocks of Peakmoor Sandstone of different volumes. Blocks were removed from simulations after 2, 5, 10, 20 and 60 cycles. Permeability measurements were taken for these blocks at a resolution of 20 mm, providing a grid of 100 permeability values for each surface. The geostatistical technique of ordinary kriging was applied to the data to produce a smoothed interpolation of permeability for these surfaces, and hence improve understanding of the evolution of permeability over time in response to repeated salt weathering cycles. Results illustrate the different responses of the sandstone blocks of different volumes to repeated salt weathering cycles. In both cases, after an initial subtle decline in the permeability (reflecting pore blocking), the permeability starts to increase — reflected in a rise in mean, maximum and minimum values. However, between 10 and 20 cycles, there is a jump in the mean and range permeability of the group A block surfaces coinciding with the onset of meaningful debris release. After 60 cycles, the range of permeability in the group A block surface had increased markedly, suggesting the development of a secondary permeability. The concept of dynamic instability and divergent behaviour is applied at the scale of a single block surface, with initial small-scale differences across a surface having larger scale consequences as weathering progresses. After cycle 10, group B blocks show a much smaller increase in mean permeability, and the range stays relatively steady — this may be explained by the capillary conditions set up by the smaller volume of the stone, allowing salts to migrate to the 'back' of the blocks and effectively relieving stress at the 'front' face.

  3. Efficient Methods of Estimating the Operating Characteristics of Item Response Categories and Challenge to a New Model for the Multiple-Choice Item. Final Report.

    ERIC Educational Resources Information Center

    Samejima, Fumiko

    In defense of retaining the "latent trait theory" term, instead of replacing it with "item response theory" as some recent research would have it, the following objectives are outlined: (1) investigation of theory and method for estimating the operating characteristics of discrete item responses using a minimum number of examinees and assuming no…

  4. A piloted simulation of helicopter air combat to investigate effects of variations in selected performance and control response characteristics

    NASA Technical Reports Server (NTRS)

    Lewis, Michael S.; Mansur, M. Hossein; Chen, Robert T. N.

    1987-01-01

    A piloted simulation study investigating handling qualities and flight characteristics required for helicopter air to air combat is presented. The Helicopter Air Combat system was used to investigate this role for Army rotorcraft. Experimental variables were the maneuver envelope size (load factor and sideslip), directional axis handling qualities, and pitch and roll control-response type. Over 450 simulated, low altitude, one-on-one engagements were conducted. Results from the experiment indicate that a well damped directional response, low sideforce caused by sideslip, and some effective dihedral are all desirable for weapon system performance, good handling qualities, and low pilot workload. An angular rate command system was favored over the attitude type pitch and roll response for most applications, and an enhanced maneuver envelope size over that of current generation aircraft was found to be advantageous. Pilot technique, background, and experience are additional factors which had a significant effect on performance in the air combat tasks investigated. The implication of these results on design requirements for future helicopters is presented.

  5. Establishing Chinese medicine characteristic tumor response evaluation system is the key to promote internationalization of Chinese medicine oncology.

    PubMed

    Li, Jie; Li, Lei; Liu, Rui; Lin, Hong-sheng

    2012-10-01

    The features and advantages of Chinese medicine (CM) in cancer comprehensive treatment have been in the spotlight of experts both at home and abroad. However, how to evaluate the effect of CM more objectively, scientifically and systematically is still the key problem of clinical trial, and also a limitation to the development and internationalization of CM oncology. The change of tumor response evaluation system in conventional medicine is gradually consistent with the features of CM clinical effect, such as they both focus on a combination of soft endpoints (i.e. quality of life, clinical benefit, etc.) and hard endpoints (i.e. tumor remission rate, time to progress, etc.). Although experts have proposed protocols of CM tumor response evaluation criteria and come to an agreement in general, divergences still exist in the importance, quantification and CM feature of the potential endpoints. Thus, establishing a CM characteristic and wildly accepted tumor response evaluation system is the key to promote internationalization of CM oncology, and also provides a more convenient and scientific platform for CM international cooperation and communication. PMID:22965698

  6. Early traumatized inpatients high in psychoform and somatoform dissociation: characteristics and treatment response.

    PubMed

    Jepsen, Ellen K K; Langeland, Willie; Heir, Trond

    2014-01-01

    This study examined the clinical relevance of differences in psychoform and somatoform dissociative symptoms in 55 early traumatized inpatients. The high psychoform and somatoform dissociative group (n = 18), somatoform dissociative group (n = 22), and nondissociative group (n = 15) did not differ on abuse severity, depressive symptoms, interpersonal problems, Axis I or II comorbidity, or deterioration rates. Compared to the other 2 groups, the highly dissociative group was characterized by younger age, living alone, higher levels of posttraumatic and general distress, more frequent reports of suicidality, self-mutilation, eating problems, and less favorable treatment response. The results highlight the clinical relevance of using dissociation measures for identifying subgroups of patients with severe psychopathology who may be more treatment resistant. PMID:24983399

  7. Cellular Responses Evoked by Different Surface Characteristics of Intraosseous Titanium Implants

    PubMed Central

    Feller, Liviu; Jadwat, Yusuf; Khammissa, Razia A. G.; Meyerov, Robin; Lemmer, Johan

    2015-01-01

    The properties of biomaterials, including their surface microstructural topography and their surface chemistry or surface energy/wettability, affect cellular responses such as cell adhesion, proliferation, and migration. The nanotopography of moderately rough implant surfaces enhances the production of biological mediators in the peri-implant microenvironment with consequent recruitment of differentiating osteogenic cells to the implant surface and stimulates osteogenic maturation. Implant surfaces with moderately rough topography and with high surface energy promote osteogenesis, increase the ratio of bone-to-implant contact, and increase the bonding strength of the bone to the implant at the interface. Certain features of implant surface chemistry are also important in enhancing peri-implant bone wound healing. It is the purpose of this paper to review some of the more important features of titanium implant surfaces which have an impact on osseointegration. PMID:25767803

  8. Teacher Characteristics Associated with Responsiveness and Exposure to Consultation and On-line Professional Development Resources

    PubMed Central

    Downer, Jason T.; Locasale-Crouch, Jennifer; Hamre, Bridget; Pianta, Robert

    2014-01-01

    This paper is a natural follow-up to intent-to-treat findings indicating that the MyTeachingPartner Consultancy, inclusive of on-line video resources and web-mediated consultation, improved the quality of pre-k teachers’ interactions with children. This study takes a close look at implementation fidelity within the effective MTP Consultancy condition over both years of implementation, in order to learn more about the ingredients of professional development that may have contributed to the success of the intervention. Variation in teachers’ responsiveness (e.g., ratings of Consultancy worth) and exposure to the intervention (e.g., number of consultation cycles completed) are examined, with particular interest in the identification of teacher factors that may serve as supports or barriers to successfully implementing consultation supports and on-line professional development resources. PMID:25419081

  9. Fabrication of inorganic-organic composites containing ferroelectric nanoplates and evaluation of their piezoelectric response characteristics

    NASA Astrophysics Data System (ADS)

    Kishimoto, Ryo; Kobune, Masafumi; Nishioka, Hiroshi; Kikuchi, Takeyuki; Kishi, Hajime; Fujisawa, Hironori; Nakashima, Seiji; Shimizu, Masaru; Kimura, Satoshi

    2013-04-01

    a- and b-axis-oriented Bi3.25Nd0.75Ti3O12 (BNT) nanoplates, 3.0-µm thick, were fabricated on conductive Nb:TiO2(101) substrates with 0.79 mass% Nb at 650 °C by high-temperature sputtering. Successively, the fabrication of inorganic-organic composites was carried out by introducing an epoxy resin to the spaces between the BNT nanoplates. The fourier transform infrared spectroscopy (FTIR) and the energy dispersive X-ray (EDX) elemental mapping results confirmed that the fabricated composites were inorganic-organic hybridized materials with cured epoxy resin introduced into the spaces between the BNT nanoplates. Piezoelectric response measurements of the fabricated BNT-epoxy resin composites by using piezoresponse force microscopy (PFM) showed that the composites have potential as piezoelectric microelement materials.

  10. Response characteristics of basolateral and centromedial neurons in the primate amygdala

    PubMed Central

    Mosher, Clayton P.; Zimmerman, Prisca E.; Gothard, Katalin M.

    2010-01-01

    Based on cellular architecture and connectivity, the main nuclei of the primate amygdala are divided in two clusters: basolateral (BL) and centromedial (CM). These anatomical features suggest a functional division of labor among the nuclei. The BL nuclei are thought to be involved primarily in evaluating the emotional significance or context-dependent relevance of all stimuli, including social signals such as facial expressions. The CM nuclei appear to be involved in allocating attention to stimuli of high significance and in initiating situation-appropriate autonomic responses. The goal of this study was to determine how this division of labor manifests in the response properties of neurons recorded from these two nuclear groups. We recorded the activity of 454 single neurons from identified nuclear sites in three monkeys trained to perform an image viewing task. The task required orienting and attending to cues that predicted trial progression and viewing images with broadly varying emotional content. The two populations of neurons showed large overlaps in neurophysiological properties. We found, however, that CM neurons show higher firing and less regular spiking patterns than BL neurons. Furthermore, neurons in the CM nuclei were more likely to respond to task events (fixation, image-on, image-off), while neurons in the BL nuclei were more likely to respond selectively to the content of stimulus images. The overlap in the physiological properties of the CM and BL neurons suggest distributed processing across the nuclear groups. The differences, therefore, appear to be a processing bias rather than a hallmark of mutually exclusive functions. PMID:21123566

  11. Work capacity and metabolic and morphologic characteristics of the human quadriceps muscle in response to unloading

    NASA Technical Reports Server (NTRS)

    Berg, H. E.; Dudley, G. A.; Hather, B.; Tesch, P. A.

    1993-01-01

    The response of skeletal muscle to unweighting was studied in six healthy males who were subjected to four weeks of lowerlimb suspension. They performed three bouts of 30 consecutive maximal concentric knee extensions, before unloading and the day after (POST 1), 4 days after (POST 2) and 7 weeks after (REC) resumed weight-bearing. Peak torque of each contraction was recorded and work was calculated as the mean of the average peak torque for the three bouts and fatigability was measured as the decline in average peak torque over bouts. Needle biopsies were obtained from m. vastus lateralis of each limb before and at POST 1. Muscle fibre type composition and area, capillarity and the enzyme activities of citrate synthase (CS) and phosphofructokinase (PFK) were subsequently analysed. Mean average peak torque for the three bouts at POST1, POST2 and REC was reduced (P < 0.05) by 17, 13 and 7%, respectively. Fatigability was greater (P < 0.05) at POST2 than before unloading. Type I, IIA and IIB percentage, Type I and II area and capillaries per fibre of Type I and II did not change (P > 0.05) in response to unloading. The activity of CS, but not PFK, decreased (P < 0.05) after unloading. The weight-bearing limb showed no changes in the variables measured. The results of this study suggest that this human lowerlimb suspension model produces substantial impairments of work and oxidative capacity of skeletal muscle. The performance decrements are most likely induced by lack of weight-bearing.

  12. Response surface optimization of pH and ionic strength for emulsion characteristics of egg yolk.

    PubMed

    Kurt, S; Zorba, O

    2009-11-01

    Effects of pH (3.5, 4.5, 6.0, 7.5, and 8.5) and ionic strength (0.05, 0.15, 0.30, 0.45, and 0.55 M NaCl) on emulsion capacity, emulsion stability (ES), apparent yield stress of emulsion (AYS), and emulsion density (ED) of egg yolk were studied by using a model system. Ionic strength and pH had significant (P < 0.01) effects on the emulsion characteristics of egg yolk. Their interaction effects also have been found significant on ES, AYS, and ED. Predicted solutions of ES, emulsion capacity, and ED were minimum. The critical point of ES was determined to be at pH 6.08 and an ionic strength of 0.49 (M NaCl). Predicted solution for AYS was a maximum, which was determined to be at pH 6.04 and an ionic strength of 0.29 (M NaCl). Optimum values of pH and ionic strenght were 4.61 to 7.43 and 0.10 to 0.47, respectively. PMID:19834095

  13. Metal oxide nanomaterials in seawater: linking physicochemical characteristics with biological response in sea urchin development.

    PubMed

    Fairbairn, Elise A; Keller, Arturo A; Mädler, Lutz; Zhou, Dongxu; Pokhrel, Suman; Cherr, Gary N

    2011-09-15

    The fate and behavior of nanomaterials (NMs) in environmental media has important consequences for toxicity. The majority of aquatic research to date has focused on NM behavior in freshwater systems. However, pH and salinity differences of seawater affect dissolution and aggregation of NMs. In this study, physical characteristics of metal oxide NMs in seawater were linked with their toxicity to developing sea urchins. The metal oxide NMs TiO(2) and CeO(2) up to 10mg/L were not toxic to the embryos of the white sea urchin (Lytechinus pictus). In contrast, ZnO NM was highly toxic to these embryos (EC(50) = 99.5 ?g/L). The toxicity of ZnO NM was not significantly different from bulk ZnO or soluble Zn(2+) (from ZnSO(4) · 7H(2)O), suggesting that the toxicity of ZnO NM can be attributed to soluble Zn(2+). Furthermore, solubility data indicate that at the concentrations used in our sea urchin embryo experiments, ZnO NM was rapidly and completely solubilized in seawater. The present study also demonstrated that Fe-doped NMs were less soluble in seawater compared to pure ZnO NMs, but there was no concomitant reduction in toxicity. PMID:21775060

  14. Broadband energy harvesting by exploiting nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate

    NASA Astrophysics Data System (ADS)

    Li, Hao; Dai, Fuhong; Du, Shanyi

    2015-04-01

    Recently bistable composite laminates have been investigated for broadband energy harvesting, by taking advantage of their nonlinear oscillations around the first vibration mode. However, it has been reported that the excitation acceleration needed for the desired large amplitude limit cycle oscillation is too high, if the first vibration mode is elevated to relative higher frequencies (60 Hz e.g.). This study investigates the feasibility of exploiting the nonlinear oscillations around the second vibration mode of a rectangular piezoelectric bistable laminate (RPBL), for broadband vibration energy harvesting at relative higher frequencies, but with relative low excitation acceleration. The proposed RPBL has three oscillation patterns around the second vibration mode, including single-well oscillation, chaotic intermittency oscillation and limit cycle oscillation. The broadband characteristics and the considerable energy conversion efficiency of the RPBL are demonstrated in experiments. The static nonlinearity and the dynamic responses of the RPBL are investigated by finite element method. Finite element analysis (FEA) reveals that the enhanced dynamic responses of the RPBL are due to its softening bending stiffness and the local snap through phenomenon. The FEA results coincide reasonably well with experimental results.

  15. Application of the Transmission Bragg Gratings for Vibration Monitoring

    E-print Network

    Tikhonov, E A

    2010-01-01

    It is shown that the optical-electronic system consisted of the transmission Bragg grating, a laser and the intermediate sensitive to the vibrations mirror can detect the vibrations, when touched by them laser beam scan will exceed the angular divergence of the beam. The mathematical model of the sensor of the vibrations presented in the form of Taylor series describes the system response taking into account the operating point, in particular, describes the effect of the doubling of the modulation frequency response relative to the frequency of acting vibrations.

  16. An image based vibration sensor for soft tissue modal analysis in a Digital Image Elasto Tomography (DIET) system

    Microsoft Academic Search

    Sheng Feng; Thomas Lotz; J Geoffrey Chase; Christopher E Hann

    2010-01-01

    Digital Image Elasto Tomography (DIET) is a non-invasive elastographic breast cancer screening technology, based on image-based measurement of surface vibrations induced on a breast by mechanical actuation. Knowledge of frequency response characteristics of a breast prior to imaging is critical to maximize the imaging signal and diagnostic capability of the system. A feasibility analysis for a non-invasive image based modal

  17. A Lyapunov Exponent Approach for Identifying Chaotic Behavior in a Finite Element Based Drillstring Vibration Model 

    E-print Network

    Mongkolcheep, Kathira

    2010-10-12

    for computing Lyapunov exponents of other types of nonlinear vibrating systems with many degrees of freedom. Vibration response predictions may assist drilling rig operators in changing a variety of controlled parameters to improve operation procedures and...

  18. Anti-vibration gloves?

    PubMed

    Hewitt, Sue; Dong, Ren G; Welcome, Daniel E; McDowell, Thomas W

    2015-03-01

    For exposure to hand-transmitted vibration (HTV), personal protective equipment is sold in the form of anti-vibration (AV) gloves, but it remains unclear how much these gloves actually reduce vibration exposure or prevent the development of hand-arm vibration syndrome in the workplace. This commentary describes some of the issues that surround the classification of AV gloves, the assessment of their effectiveness and their applicability in the workplace. The available information shows that AV gloves are unreliable as devices for controlling HTV exposures. Other means of vibration control, such as using alternative production techniques, low-vibration machinery, routine preventative maintenance regimes, and controlling exposure durations are far more likely to deliver effective vibration reductions and should be implemented. Furthermore, AV gloves may introduce some adverse effects such as increasing grip force and reducing manual dexterity. Therefore, one should balance the benefits of AV gloves and their potential adverse effects if their use is considered. PMID:25381184

  19. Vibration monitoring of high speed spindles using spectral analysis techniques

    Microsoft Academic Search

    S. Vafaei; H. Rahnejat; R. Aini

    2002-01-01

    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

  20. THE APPLICATION OF ULTRASONIC VIBRATION DRILLS IN TRAUMATOLOGY

    Microsoft Academic Search

    S. E. Kvashnin; E. V. Bosova

    2003-01-01

    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.

  1. Experimental and theoretical study of a premixed vibrating flame

    Microsoft Academic Search

    F. Baillot; D. Durox; R. PrudHomme

    1992-01-01

    This paper reports on an experimental study of vibrating flames above a cylindrical burner which has been conducted in order to examine some of the fundamental characteristics of the flow perturbations-combustion interaction. Here the perturbation chosen is a space-time sinusoidal flow velocity. The vibrational nature of the flow has been studied with the without the flame, using a LDV setup

  2. A Study of Vibration Control Systems for Superconducting Maglev Vehicles

    Microsoft Academic Search

    Ken Watanabe; Hiroshi Yoshioka; Erimitsu Suzuki; Takayuki Tohtake; Masao Nagai

    2007-01-01

    To enhance ride comfort in the superconducting magnetically levitated transport (Maglev) system, vibrations were reduced by controlling the secondary suspension between the car body and bogie. To reduce vibrations at the relatively high characteristic frequencies of the primary suspension, attention has been directed toward control using damping forces output by a linear generator system integrated into a bogie for on-board

  3. Probabilistic outlier detection in vibration spectra with small learning dataset

    E-print Network

    Paris-Sud XI, Université de

    , and on the characteristic patterns of potential faults. With vibration measured from a bearing test rig and from an aircraft, rotating machine, bearing, aircraft engine, bayesian inference, periodogram, maximum, excess, wavelet is the monitoring of vibrations in aircraft engines, but simpler test cases are also dealt with, for example bearing

  4. Vibration-Based Damage Detection in Rotating Machinery

    Microsoft Academic Search

    Charles R. Farrar; Thomas A. Duffey

    1999-01-01

    Damage detection as determined from changes in the vibration characteristics of a system has been a popular research topic for the last thirty years. Numerous damage identification algorithms have been proposed for detecting and locating damage in structural and mechanical systems. To date, these damage-detection methods have shown mixed results. A particular application of vibration-based damage detection that has perhaps

  5. Comparative Characteristics of Porous Bioceramics for an Osteogenic Response In Vitro and In Vivo

    PubMed Central

    Lee, Hye-Rim; Kim, Han-Jun; Ko, Ji-Seung; Choi, Yong-Suk; Ahn, Myun-Whan; Kim, Sukyoung; Do, Sun Hee

    2013-01-01

    Porous calcium phosphate ceramics are used in orthopedic and craniofacial applications to treat bone loss, or in dental applications to replace missing teeth. The implantation of these materials, however, does not induce stem cell differentiation, so suitable additional materials such as porous calcium phosphate discs are needed to influence physicochemical responses or structural changes. Rabbit adipose-derived stem cells (ADSC) and mouse osteoblastic cells (MC3T3-E1) were evaluated in vitro by the MTT assay, semi-quantitative RT-PCR, and immunoblotting using cells cultured in medium supplemented with extracts from bioceramics, including calcium metaphosphate (CMP), hydroxyapatite (HA) and collagen-grafted HA (HA-col). In vivo evaluation of the bone forming capacity of these bioceramics in rat models using femur defects and intramuscular implants for 12 weeks was performed. Histological analysis showed that newly formed stromal-rich tissues were observed in all the implanted regions and that the implants showed positive immunoreaction against type I collagen and alkaline phosphatase (ALP). The intramuscular implant region, in particular, showed strong positive immunoreactivity for both type I collagen and ALP, which was further confirmed by mRNA expression and immunoblotting results, indicating that each bioceramic material enhanced osteogenesis stimulation. These results support our hypothesis that smart bioceramics can induce osteoconduction and osteoinduction in vivo, although mature bone formation, including lacunae, osteocytes, and mineralization, was not prominent until 12 weeks after implantation. PMID:24391927

  6. Effect of Ground Motion Characteristics on the Seismic Response of a Monumental Concrete Arch Bridge

    SciTech Connect

    Caglayan, B. Ozden; Ozakgul, Kadir; Tezer, Ovunc [Department of Civil Engineering, ITU Istanbul Technical University, 34469 Maslak, Istanbul (Turkey)

    2008-07-08

    Railway network in Turkey dates back to more than a hundred years ago and according to official records, there are approximately 18,000 railway bridges with spans varying between 50 cm up to 150 meters. One of them is a monumental concrete arch bridge with a total length of 210 meters having three major spans of 30 meters and a height of 65 meters, located in an earthquake-prone region in southern part of the country. Three-dimensional finite element model of the bridge was generated using a commercially available general finite element analysis software and based on the outcomes of a series of in-depth acceleration measurements that were conducted on-site, the model was refined. Types of ground motion records were used to investigate the seismic response and vulnerability of this massive structure in order to provide information regarding (i) damage-susceptible regions of the structure for monitoring purposes, and, (ii) seismic loads to be taken into account during evaluation and possible strengthening phases for this type of structures.

  7. Erythrocyte characteristics in vitamin E-responsive anemia of the owl monkey (Aotus trivirgatus).

    PubMed

    Brady, P S; Sehgal, P K; Hayes, K C

    1982-08-01

    To characterize the vitamin E-responsive anemia occurring in owl monkeys (Aotus trivirgatus), osmotic fragility, and H2O2-induced and time-dependent hemolysis, as well as RBC lipid peroxidation, were compared in anemic and nonanemic owl monkeys. Whereas vitamin E serves as a lipid-soluble antioxidant, the glutathione peroxidase system functions in the water-soluble phase of the cell. Thus, activity of glutathione peroxidase, glutathione reductase, and glucose-6-phosphate dehydrogenase, as well as reduced glutathione concentrations in owl monkeys' RBC, were compared with those of rhesus macaques and cebus and squirrel monkeys fed the same diet and maintained under the same management scheme. Osmotic fragility did not differ between anemic and nonanemic owl monkeys. The H2O2-induced and time-dependent hemolysis was approximately 10-fold greater among anemia owl monkeys than among their nonanemic counterparts, and lipid peroxidation values tended to be higher in the anemic monkeys. Owl monkeys, as a species and independent of anemia, exhibited higher RBC peroxidation than did 2 other New World species, cebus and squirrel monkeys. The glutathione peroxidase system was not depressed in owl monkey RBC. The only observed difference in this system was in the glucose-6-phosphate dehydrogenase activity, which was 3- to 6-fold higher in the owl monkey than in the other species, indicating an increased activity of the peroxidase system. Thus, a defect in the glutathione peroxidase system could not be identified. PMID:7103234

  8. Behavioral characteristics of Internet gamblers who trigger corporate responsible gambling interventions.

    PubMed

    Gray, Heather M; LaPlante, Debi A; Shaffer, Howard J

    2012-09-01

    As the worldwide popularity of Internet gambling increases, concerns about the potential for gambling-related harm also increase. This paper reports the results of a study examining actual Internet gambling behavior during 10 years of play. We examined the electronic gambling records of subscribers (N=2,066) who triggered a responsible gaming alert system at a large international online gaming company. We compared these cases with control subscribers (N=2,066) who had the same amount of exposure to the Internet gambling service provider. We used discriminant function analysis to explore what aspects of gambling behavior distinguish cases from controls. Indices of the intensity of gambling activity (e.g., total number of bets made, number of bets per betting day) best distinguished cases from controls, particularly in the case of live-action sports betting. Control group players evidenced behavior similar to the population of players using this service. These results add to our understanding of behavioral markers for disordered Internet gambling and will aid in the development of behavior-based algorithms capable of predicting the presence and/or the onset of disordered Internet gambling. PMID:22686960

  9. Effect of stiffness characteristics on the response of composite grid-stiffened structures

    NASA Technical Reports Server (NTRS)

    Ambur, Damodar R.; Rehfield, Lawrence W.

    1991-01-01

    A study of the effect of stiffness discontinuities and structural parameters on the response of continuous-filament grid-stiffened flat panels is presented. The buckling load degradation due to manufacturing-introduced stiffener discontinuities associated with a filament cut-and-add approach at the stiffener intersections is investigated. The degradation of buckling resistance in isogrid flat panels subjected to uni-axial compression and combined axial compression and shear loading conditions and induced damage is quantified using FEM. The combined loading case is the most critical one. Nonsolid stiffener cross sections, such as a foam-filled blade or hat with a 0-deg dominant cap, result in grid-stiffened structures that are structurally very efficient for wing and fuselage applications. The results of a study of the ability of grid-stiffened structural concepts to enhance the effective Poisson's ratio of a panel are presented. Grid-stiffened concepts create a highly effective Poisson's ratio, which can produce large camber deformations for certain elastic tailoring applications.

  10. Effects of Control-Response Characteristics on the Capability of Helicopter for Use as a Gun Platform

    NASA Technical Reports Server (NTRS)

    Pegg, Robert J.; Connor, Andrew B.

    1960-01-01

    An investigation with a variable-stability helicopter was undertaken to ascertain the steadiness and ability to "hold on" to the target of a helicopter employed as a gun platform. Simulated tasks were per formed under differing flight conditions with the control-response characteristics of the helicopter varied for each task. The simulated gun-platform mission included: Variations of headings with respect to wind, constant altitude and "swing around" to a wind heading of 0 deg, and increases in altitude while performing a swing around to a wind heading of 0 deg. The results showed that increases in control power and damping increased pilot ability to hold on to the target with fewer yawing oscillations and in a shorter time. The results also indicated that wind direction must be considered in accuracy assessment. Greatest accuracy throughout these tests was achieved by aiming upwind.

  11. Enhanced switching characteristics and piezoelectric response in epitaxial BiFeO3-TbMnO3 thin films

    NASA Astrophysics Data System (ADS)

    Li, Wei; Wang, Yiping; Nie, Pengxiao; Hu, Querui; Yang, Ying; Yuan, Guoliang

    2015-06-01

    High-quality (001) oriented epitaxial 0.9BiFeO3-0.1TbMnO3 thin films were grown on La2/3Sr1/3MnO3 and SrRuO3 buffered SrTiO3 substrate using pulsed laser deposition. X-ray diffraction showed that the films are single-phase perovskite without secondary impurity phases. Domain structures and upward ferroelectric self-poling phenomenon were distinctly observed in both films with compressive epitaxial strains. Furthermore, the upward self-poling disappears in polycrystalline 0.9BiFeO3-0.1TbMnO3 thin film on Pt/TiO2/SiO2/Si substrates. Through local switching spectroscopy measurements, the evidence of enhanced ferroelectric switching and piezoelectric response characteristics have been provided.

  12. Physicochemical responses and microbial characteristics of shiitake mushroom (Lentinus edodes) to gum arabic coating enriched with natamycin during storage.

    PubMed

    Jiang, Tianjia; Feng, Lifang; Zheng, Xiaolin; Li, Jianrong

    2013-06-01

    Physicochemical responses and microbial characteristics of shiitake mushroom (Lentinus edodes) to gum arabic (GA) coating incorporating natamycin (NA) during storage were investigated. Mushroom weight loss, firmness, total soluble solids, total sugar, reducing sugar, ascorbic acid, and microbial and sensory quality were measured. Mushroom coated with gum arabic+natamycin (GANA) maintained tissue firmness and showed reduction in microbial counts from yeasts and moulds compared with the control. In addition, GANA coating also delayed changes in the soluble solids concentration, total sugar and ascorbic acid. Sensory evaluation proved the efficacy of GANA coating by maintaining the overall quality of shiitake mushroom during the storage period. The efficiency was better than that of GA or NA treatment alone. Our study suggests that GANA has the potential to improve the quality of shiitake mushroom and extend its shelf-life up to 16d. PMID:23411335

  13. Eggshell Cutter Using Ultrasonic Vibration

    NASA Astrophysics Data System (ADS)

    Miura, Hikaru

    2003-05-01

    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.

  14. Triple X syndrome: characteristics of 42 Italian girls and parental emotional response to prenatal diagnosis.

    PubMed

    Lalatta, Faustina; Quagliarini, Donatella; Folliero, Emanuela; Cavallari, Ugo; Gentilin, Barbara; Castorina, Pierangela; Forzano, Francesca; Forzano, Serena; Grosso, Enrico; Viassolo, Valeria; Naretto, Valeria Giorgia; Gattone, Stefania; Ceriani, Florinda; Faravelli, Francesca; Gargantini, Luigi

    2010-10-01

    We report clinical and behavioural evaluation data in 42 Italian girls with triple X syndrome whose diagnosis was made prenatally between 1998 and 2006 in three Italian centres. At initial evaluation, reproductive and medical histories were collected. Clinical assessment of the child was performed by a clinical geneticist and included a detailed personal history, physical evaluation and auxological measurements. To analyse how parents coped with specific events in the prenatal and postnatal periods, we conducted an interview that included 35 specific questions designed to elicit retrospective judgements on prenatal communication, present and future worries, needs and expectations. In a subset of probands, we also administered the formal Italian Temperament Questionnaire assessment test that investigates adaptation, general environment and socialisation. This test also assesses the emotional component of temperament. Clinical results in the affected children are similar to those previously reported with evidence of increased growth in the pre-puberal age and an average incidence of congenital malformation and health needs. Median age for the time first words were pronounced was 12 months, showing a slight delay in language skills, which tended to improve by the time they reached school age. Parental responses to the interview demonstrated residual anxiety but with a satisfactory adaptation to and a positive recall of the prenatal counselling session. Parental adaptation of the 47,XXX girls require indeed a proper educational support. This support seems to be available in Italy. An integrated approach to prenatal counselling is the best way to manage the anxiety and falsely imagined consequences that parents feel after being told that their foetus bears such a genetic abnormality. PMID:20473517

  15. Characteristic of the Pepper CaRGA2 Gene in Defense Responses against Phytophthora capsici Leonian

    PubMed Central

    Zhang, Ying-Li; Jia, Qing-Li; Li, Da-Wei; Wang, Jun-E; Yin, Yan-Xu; Gong, Zhen-Hui

    2013-01-01

    The most significant threat to pepper production worldwide is the Phytophthora blight, which is caused by the oomycete pathogen, Phytophthora capsici Leonian. In an effort to help control this disease, we isolated and characterized a P. capsici resistance gene, CaRGA2, from a high resistant pepper (C. annuum CM334) and analyzed its function by the method of real-time PCR and virus-induced gene silencing (VIGS). The CaRGA2 has a full-length cDNA of 3,018 bp with 2,874 bp open reading frame (ORF) and encodes a 957-aa protein. The protein has a predicted molecular weight of 108.6 kDa, and the isoelectric point is 8.106. Quantitative real-time PCR indicated that CaRGA2 expression was rapidly induced by P. capsici. The gene expression pattern was different between the resistant and susceptible cultivars. CaRGA2 was quickly expressed in the resistant cultivar, CM334, and reached to a peak at 24 h after inoculation with P. capsici, five-fold higher than that of susceptible cultivar. Our results suggest that CaRGA2 has a distinct pattern of expression and plays a critical role in P. capsici stress tolerance. When the CaRGA2 gene was silenced via VIGS, the resistance level was clearly suppressed, an observation that was supported by semi-quantitative RT-PCR and detached leave inoculation. VIGS analysis revealed their importance in the surveillance to P. capsici in pepper. Our results support the idea that the CaRGA2 gene may show their response in resistance against P. capsici. These analyses will aid in an effort towards breeding for broad and durable resistance in economically important pepper cultivars. PMID:23698759

  16. A review of fire effects on vegetation and soils in the Great Basin region: response and ecological site characteristics

    USGS Publications Warehouse

    Miller, Richard F.; Chambers, Jeanne C.; Pyke, David A.; Pierson, Fred B.; Williams, C. Jason

    2013-01-01

    This review synthesizes the state of knowledge on fire effects on vegetation and soils in semi-arid ecosystems in the Great Basin Region, including the central and northern Great Basin and Range, Columbia River Basin, and the Snake River Plain. We summarize available literature related to: (1) the effects of environmental gradients, ecological site, and vegetation characteristics on resilience to disturbance and resistance to invasive species; (2) the effects of fire on individual plant species and communities, biological soil crusts, seed banks, soil nutrients, and hydrology; and (3) the role of fire severity, fire versus fire surrogate treatments, and post-fire grazing in determining ecosystem response. From this, we identify knowledge gaps and present a framework for predicting plant successional trajectories following wild and prescribed fires and fire surrogate treatments. Possibly the three most important ecological site characteristics that influence a site’s resilience (ability of the ecological site to recover from disturbance) and resistance to invasive species are soil temperature/moisture regimes and the composition and structure of vegetation on the ecological site just prior to the disturbance event.

  17. Characteristics and response of mouse bone marrow derived novel low adherent mesenchymal stem cells acquired by quantification of extracellular matrix

    PubMed Central

    Zheng, Ri-Cheng; Heo, Seong-Joo; Koak, Jai-Young; Lee, Joo-Hee; Park, Ji-Man

    2014-01-01

    PURPOSE The aim of present study was to identify characteristic and response of mouse bone marrow (BM) derived low-adherent bone marrow mesenchymal stem cells (BMMSCs) obtained by quantification of extracellular matrix (ECM). MATERIALS AND METHODS Non-adherent cells acquired by ECM coated dishes were termed low-adherent BMMSCs and these cells were analyzed by in vitro and in vivo methods, including colony forming unit fibroblast (CFU-f), bromodeoxyuridine (BrdU), multi-potential differentiation, flow cytometry and transplantation into nude mouse to measure the bone formation ability of these low-adherent BMMSCs. Titanium (Ti) discs with machined and anodized surfaces were prepared. Adherent and low-adherent BMMSCs were cultured on the Ti discs for testing their proliferation. RESULTS The amount of CFU-f cells was significantly higher when non-adherent cells were cultured on ECM coated dishes, which was made by 7 days culturing of adherent BMMSCs. Low-adherent BMMSCs had proliferation and differentiation potential as adherent BMMSCs in vitro. The mean amount bone formation of adherent and low-adherent BMMSCs was also investigated in vivo. There was higher cell proliferation appearance in adherent and low-adherent BMMSCs seeded on anodized Ti discs than machined Ti discs by time. CONCLUSION Low-adherent BMMSCs acquired by ECM from non-adherent cell populations maintained potential characteristic similar to those of the adherent BMMSCs and therefore could be used effectively as adherent BMMSCs in clinic. PMID:25352957

  18. Enhanced Oil Recovery with Downhole Vibration Stimulation in Osage County Oklahoma

    SciTech Connect

    J. Ford Brett; Robert V. Westermark

    2001-03-31

    The objective of this project is to demonstrate the impact of downhole vibration stimulation on oil production rates in a mature waterflood field. Oil & Gas Consultants International, Inc. (OGCI) will manage the project in close cooperation with the Osage Tribe as the tests will be conducted in Osage County, Oklahoma, the mineral estate of the Osage Tribe. The field is owned and operated by Calumet Oil Company. Phillips Petroleum Company will contribute their proprietary vibration core analysis of cores recovered from the pilot test area. To achieve the project objectives, the work has been divided into nine tasks, some are concurrent, while other tasks rely on completion of previous steps. The operator, Calumet Oil Company operates several field in Osage County Oklahoma. The North Burbank Unit will be the site of the test. The team will then determine where within the field to optimally locate the vibration test well. With the location determined, the test well will be drilled, cored, logged and 7-inch production casing run and cemented. In a parallel effort, OGCI will be designing, building, and testing a new version of the downhole vibration tool based on their patented and field proven whirling orbital vibrator. With the field test tool built to run in 7-inch casing. Reliability testing of the downhole tool and surface power source will be conducted in nearby field operated by Calumet Oil Company. After the core is recovered, Phillips Petroleum Company will be conducting laboratory tests utilizing their proprietary sonic core apparatus to determine fluid flow response to a range of vibration frequencies. These results, in turn, will allow final adjustments to the frequency generation mechanisms of the downhole vibration tool. One or more offset wells, near to the vibration test well, will be equipped with downhole geophones and or hydro-phones to determine the strength of signal and if the producing formation has a characteristic resonant frequency response. Surface geophones will also be set out and arranged to pick up the signal generated by the downhole vibration tool. The downhole vibrator will be installed in the test well. Monitoring the production and injection for the pilot test area will continue. As the frequency of the downhole tool is changed, the recording of seismic signals, both on the surface and downhole, will also be conducted. The results of the data collection will be a matrix of varying vibration stimulation conditions corresponding to changes in production fluid rates and seismic responses. The report on the results of the downhole vibration stimulation will be prepared and delivered using several venues. Technical papers will be submitted to the Society of Petroleum Engineers. Workshops are planned to be held for operators in Osage County and surrounding areas. A dedicated technical session on vibration stimulation may be offered at the 2002 SPE/DOE/IOR Conference, bringing together the world's experts in this emerging technology. The final task will be to close out the project.

  19. Electrophysiological characteristics of hamster dorsal root ganglion cells and their response to axotomy.

    PubMed

    Gurtu, S; Smith, P A

    1988-02-01

    1. The active and passive membrane properties of neurons in the lower lumbar (L6, L7) or sacral (S1) dorsal root ganglia from golden hamsters were examined in vitro by means of conventional intracellular recording techniques. Data were collected from neurons exhibiting action potentials (AP) of 70 mV or more in amplitude. 2. Cells with axonal conduction velocities (CV) greater than 20 m/s were termed fast-A-cells, those with CVs between 2.5 and 20 m/s were termed A-delta-cells, and those with CVs less than 1 m/s were termed C-cells. 3. Fast-A-cells usually exhibited short-duration APs (2.51 +/- 0.41 ms, n = 19) followed by short (less than 50 ms) afterhyperpolarizations (AHPs). C-cells usually exhibited long-duration APs (10.5 +/- 0.69 ms, n = 18) followed by long-duration AHPs (much greater than 50 ms). The characteristics of APs in A-delta-cells (AP mean duration 3.34 +/- 0.42 ms, n = 32) were intermediate between those of fast-A- and C-cells. Long AHPs (duration much greater than 50 ms) were manifest in 43.8% of A-delta-cells. 4. A time-dependent sag in hyperpolarizing electrotonic potentials (rectification) was found in 68.8% of fast-A-cells, 45.5% of A-delta-cells, and 62.5% of C-cells. 5. To examine neuronal properties 1-6 wk after transection of the sciatic nerve (axotomy), cells were reclassified as SAP (short action potential) cells and LAP (long action potential) cells. Cells in the SAP category had AP durations less than 5 ms and included all fast-A-cells and the majority of A-delta-cells. The LAP category included cells with AP durations greater than 8 ms contained only C-cells. 6. Axotomy failed to decrease the CV of LAP cells or A-delta-cells in the SAP group. The CV of LAP cells may have increased (P less than 0.05), whereas that of SAP cells was unchanged. 7. The duration of the AP and AHP of SAP cells were slightly increased (0.1 greater than P greater than 0.05), whereas AP and AHP duration of LAP cells were unchanged after axotomy. AHP amplitudes of all cell types tended to be smaller (0.1 greater than P greater than 0.05). Axotomy did not alter the resting membrane potential or reduce the incidence of rectification in any cell type. 8. Invasion of the soma by axonally evoked APs was impeded in all cell types after axotomy even though a decrease (P less than 0.05) in rheobase of SAP cells occurred.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3351568

  20. Noise & Vibration Ctrl What's noise and what's vibration?

    E-print Network

    Berlin,Technische Universität

    Institut für Technische Akustik Noise & Vibration Ctrl · What's noise and what's vibration? ­ Noise = unwanted sound ­ Vibration = oscillations of structures © Prof. B.A.T. Petersson #12;Institut für Technische Akustik Noise & Vibration Ctrl. · What's Noise & Vibration Control? Genera t ion Transmiss ion

  1. Photothermal Study of Free and Forced Elastic Vibrations of Microcantilevers

    NASA Astrophysics Data System (ADS)

    Todorovic, D. M.; Cretin, B.; Vairac, P.; Song, Y.; Rabasovic, M. D.; Markushev, D. D.

    2015-01-01

    Dynamic free (spontaneous) and forced (optically excited) elastic vibration spectra of a cantilever (CL) were studied. The amplitude and phase elastic displacements of silicon CLs were measured as a function of the modulation frequency with and without optical excitation. Typically, four obvious peaks can be observed in the elastic vibration spectrum. The first peak represents the forced vibrations at the same frequency as the modulation of laser excitation, while two other peaks are the third and fifth harmonics. One small peak is the first natural resonance of the CL (free vibrations, spontaneous vibrations). The amplitude of elastic vibrations without optical excitation changes with frequency, and it is possible to distinguish two frequency regions. In the high frequency range above 10 kHz, the amplitude elastic vibration spectra are not a function of the frequency which is typically for white noise. The white noise level, which corresponds to the thermomechanical noise, was found. The forced vibrations are precisely studied by modulated optical excitation where the frequency is varied from 3 kHz to 45 kHz and by measuring the response with a lock-in-amplifier (measuring the amplitude and phase of the elastic vibrations). The optically excited elastic vibrations are the consequence of thermal and electronic elastic effects in the silicon CL. The mechanical response of the optically excited CL was modeled with good approximation by a damped harmonic oscillator. The experimental amplitude and phase spectra were fitted with theoretical curves, and the quality factor near the natural (resonance) frequency was obtained.

  2. Numerical Study on Suppression of Vortex Induced Vibration of Box Girder Bridge Section by Aerodynamic Countermeasures

    Microsoft Academic Search

    Muhammad Waheed SARWAR; Takeshi ISHIHARA; Yozo FUJINO

    2007-01-01

    In this study, aerodynamic vibration control measures are used to investigate the suppression m echanism of vortex-induced vibration for box girder bridge section using three- dimensional LES turbulence model. Flow around box girder section with different aerodynamic measures is analyzed and effect of these measures on the aerodynamic characteristics of bridge section is evaluated. Forced vibration is simulated in order

  3. Vibrations of turbine engine blades by shell analysis

    NASA Technical Reports Server (NTRS)

    1980-01-01

    Several aspects are discussed which are pertinent to accurate analyses of blade vibration when the blades are modeled as shells. Two dimensional methods of analysis are developed and the characteristics of such analyses are summarized.

  4. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2004-01-09

    The objective of this program is to develop a system to both monitor the vibration of a bottomhole assembly, and to adjust the properties of an active damper in response to these measured vibrations. Phase I of this program entails modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype. The project continues to advance, but is behind the revised (14-month) schedule. Tasks 1-3 (Modeling, Specification and Design) are all essentially complete. The test bench for the Test and Evaluation (Tasks 4 & 5) has been designed and constructed. The design of the full-scale laboratory prototype and associated test equipment is complete and the components are out for manufacture. Barring any unforeseen difficulties, laboratory testing should be complete by the end of March, as currently scheduled. We anticipate the expenses through March to be approximately equal to those budgeted for Phase I.

  5. ENHANCED OIL RECOVERY WITH DOWNHOLE VIBRATION STIMULATION IN OSAGE COUNTY OKLAHOMA

    SciTech Connect

    Robert Westermark; J. Ford Brett

    2003-11-01

    This Final Report covers the entire project from July 13, 2000 to June 30, 2003. The report summarizes the details of the work done on the project entitled ''Enhanced Oil Recovery with Downhole Vibration Stimulation in Osage County Oklahoma'' under DOE Contract Number DE-FG26-00BC15191. The project was divided into nine separate tasks. This report is written in an effort to document the lessons learned during the completion of each task. Therefore each task will be discussed as the work evolved for that task throughout the duration of the project. Most of the tasks are being worked on simultaneously, but certain tasks were dependent on earlier tasks being completed. During the three years of project activities, twelve quarterly technical reports were submitted for the project. Many individual topic and task specific reports were included as appendices in the quarterly reports. Ten of these reports have been included as appendices to this final report. Two technical papers, which were written and accepted by the Society of Petroleum Engineers, have also been included as appendices. The three primary goals of the project were to build a downhole vibration tool (DHVT) to be installed in seven inch casing, conduct a field test of vibration stimulation in a mature waterflooded field and evaluate the effects of the vibration on both the produced fluid characteristics and injection well performance. The field test results are as follows: In Phase I of the field test the DHVT performed exceeding well, generating strong clean signals on command and as designed. During this phase Lawrence Berkeley National Laboratory had installed downhole geophones and hydrophones to monitor the signal generated by the downhole vibrator. The signals recorded were strong and clear. Phase II was planned to be ninety-day reservoir stimulation field test. This portion of the field tests was abruptly ended after one week of operations, when the DHVT became stuck in the well during a routine removal activity. The tool cannot operate in this condition and remains in the well. There was no response measured during or afterwards to either the produced fluids from the five production wells or in the injection characteristics of the two injection wells in the pilot test area. Monitoring the pilot area injection and production wells ceased when the field test was terminated March 14, 2003. Thus, a key goal of this project, which was to determine the effects of vibration stimulation on improving oil recovery from a mature waterflood, was not obtained. While there was no improved oil recovery effect measured, there was insufficient vibration stimulation time to expect a change to occur. No conclusion can be drawn about the effectiveness of vibration stimulation in this test.

  6. Free vibration of initially stressed composite laminates

    Microsoft Academic Search

    R. Dhanaraj; Palaninathan

    1990-01-01

    The characteristics of fundamental modes of vibration of initially stressed composite laminated plates are presented in this paper. The semiloof finite element is used in this formulation. Angle-ply and cross-ply rectangular laminates with simply supported and clamped edge conditions have been analyzed for which results have not been reported in the literature earlier. The effect of using ``the same'' and

  7. Vibrational Properties of Hydrogen Astatide, HAt

    NASA Astrophysics Data System (ADS)

    Baran, Enrique J.

    2004-03-01

    A number of theoretical studies on the bond characteristics of HAt, the heaviest hydrogen halide, have recently been reported. On the basis of these data the force constant, mean amplitudes of vibration and thermodynamic functions of this molecule have been calculated. Some comparisons with the related lighter hydracids are made.

  8. Flow-induced vibration - 1986

    Microsoft Academic Search

    S. S. Chen; J. C. Simonis; Y. S. Shin

    1986-01-01

    This book presents the papers given at a conference which examined mechanical vibrations in pipes caused by fluid flow. Topics considered at the conference included fluid excitation forces, axial flow induced vibration, fluid damping, crossflow induced vibration of multiple cylinders, two-phase flow, a computer program for vibration analysis, hydrodynamics, heat exchangers, and flow-induced vibrations of condenser tubes.

  9. Transversal vibrations of double-plate systems

    NASA Astrophysics Data System (ADS)

    Hedrih, Katica (Stevanovi?)

    2006-10-01

    This paper presents an analytical and numerical analysis of free and forced transversal vibrations of an elastically connected double-plate system. Analytical solutions of a system of coupled partial differential equations, which describe corresponding dynamical free and forced processes, are obtained using Bernoulli’s particular integral and Lagrange’s method of variation constants. It is shown that one-mode vibrations correspond to two-frequency regime for free vibrations induced by initial conditions and to three-frequency regime for forced vibrations induced by one-frequency external excitation and corresponding initial conditions. The analytical solutions show that the elastic connection between plates leads to the appearance of two-frequency regime of time function, which corresponds to one eigenamplitude function of one mode, and also that the time functions of different vibration modes are uncoupled, for each shape of vibrations. It has been proven that for both elastically connected plates, for every pair of m and n, two possibilities for appearance of the resonance dynamical states, as well as for appearance of the dynamical absorption, are present. Using the MathCad program, the corresponding visualizations of the characteristic forms of the plate middle surfaces through time are presented.

  10. Vibration Testing of an Operating Stirling Convertor

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Mark E.; Goodnight, Thomas W.

    2000-01-01

    The NASA John H. Glenn Research Center and the U.S. Department of Energy are currently developing a Stirling convertor for use as an advanced spacecraft power system for future NASA deep-space missions. As part of this development, a Stirling Technology Demonstrator Convertor (TDC) was recently tested to verify its survivability and capability of withstanding its expected launch random vibration environment. The TDC was fully operational (producing power) during the random vibration testing. The output power of the convertor was measured during the testing, and these results are discussed in this paper. Numerous accelerometers and force gauges were also present which provided information on the dynamic characteristics of the TDC and an indication of any possible damage due to vibration. These measurements will also be discussed in this paper. The vibration testing of the Stirling TDC was extremely successful. The TDC survived all its vibration testing with no structural damage or functional performance degradation. As a result of this testing, the Stirling convertor's capability to withstand vibration has been demonstrated, enabling its usage in future spacecraft power systems.

  11. Black phosphorus nanoelectromechanical resonators vibrating at very high frequencies

    NASA Astrophysics Data System (ADS)

    Wang, Zenghui; Jia, Hao; Zheng, Xuqian; Yang, Rui; Wang, Zefang; Ye, G. J.; Chen, X. H.; Shan, Jie; Feng, Philip X.-L.

    2014-12-01

    We report on the experimental demonstration of a new type of nanoelectromechanical resonator based on black phosphorus crystals. Facilitated by a highly efficient dry transfer technique, crystalline black phosphorus flakes are harnessed to enable drumhead resonators vibrating at high and very high frequencies (HF and VHF bands, up to ~100 MHz). We investigate the resonant vibrational responses from the black phosphorus crystals by devising both electrical and optical excitation schemes, in addition to measuring the undriven thermomechanical motions in these suspended nanostructures. Flakes with thicknesses from ~200 nm down to ~20 nm clearly exhibit elastic characteristics transitioning from the plate to the membrane regime. Both frequency- and time-domain measurements of the nanomechanical resonances show that very thin black phosphorus crystals hold interesting potential for moveable and vibratory devices and for semiconductor transducers where high-speed mechanical motions could be coupled to the attractive electronic and optoelectronic properties of black phosphorus.We report on the experimental demonstration of a new type of nanoelectromechanical resonator based on black phosphorus crystals. Facilitated by a highly efficient dry transfer technique, crystalline black phosphorus flakes are harnessed to enable drumhead resonators vibrating at high and very high frequencies (HF and VHF bands, up to ~100 MHz). We investigate the resonant vibrational responses from the black phosphorus crystals by devising both electrical and optical excitation schemes, in addition to measuring the undriven thermomechanical motions in these suspended nanostructures. Flakes with thicknesses from ~200 nm down to ~20 nm clearly exhibit elastic characteristics transitioning from the plate to the membrane regime. Both frequency- and time-domain measurements of the nanomechanical resonances show that very thin black phosphorus crystals hold interesting potential for moveable and vibratory devices and for semiconductor transducers where high-speed mechanical motions could be coupled to the attractive electronic and optoelectronic properties of black phosphorus. Electronic supplementary information (ESI) available: A supporting document with additional technical details is included as a separate PDF file. See DOI: 10.1039/c4nr04829f

  12. ECC-1 cells: a well-differentiated steroid-responsive endometrial cell line with characteristics of luminal epithelium.

    PubMed

    Mo, Bilan; Vendrov, Aleksandr E; Palomino, Wilder A; DuPont, Barbara R; Apparao, K B C; Lessey, Bruce A

    2006-09-01

    Endometrial cancer cell lines have provided a valuable model to study endometrial epithelial cells in vitro. Since the first development of HEC1B over 35 yr ago, many different cell lines have been isolated and described. One valuable cell line that maintains hormone responsiveness and unique stability over time is the ECC-1 cell line, developed originally by the late P.G. Satyaswaroop. In this study, we investigated some of the properties of these cells and present their salient characteristics. Like Ishikawa cells, ECC-1 cells maintain both estrogen receptors (ESR1 [ER alpha] and ESR2 [ER beta]), progesterone receptors (PR A and B; PGRs), and androgen receptors (ARs), along with the p160 steroid receptor coactivators NCOA1 (formerly SRC1), NCOA2 (formerly TIF2), and NCOA3 (formerly AIB1). The karyotype of these cells is abnormal, with multiple structural rearrangements in all cells analyzed. Unlike Ishikawa cells that express glandular epithelial antigens, ECC-1 cells maintain a luminal phenotype, with expression of KRT13 (cytokeratin 13) and KRT18 (cytokeratin 18). Apparent differences in the regulation of ESR2 also were evident in ECC-1 cells compared to Ishikawa cells. Like other endometrial cell lines, ECC-1 cells express the steroid receptor coactivators and exhibit epidermal growth factor-stimulated expression of known luminal proteins thought to be involved in implantation, including the hyaluronate receptor CD44 and SPP1 (formerly osteopontin) and CD55 (decay-accelerating factor). These characteristics appear to be stable and persistent over multiple cell passages, making this well-differentiated cell line an excellent choice to study endocrine and paracrine regulation of endometrial epithelium in vitro. PMID:16707768

  13. Effect of feedback variables on active fuzzy vibration control of micro-vibration isolation platform

    Microsoft Academic Search

    Junfang Hou; Hongbai Bai; Shuai Tao

    2008-01-01

    Concerning the active vibration control problem of micro-vibration isolation platform, the physical model of the six-DOF platform was built. Fuzzy control of the modal decoupled subsystem with one degree of freedom was emulated with deviation of displacement, velocity and acceleration and the rate of change as the two-dimensional feedback variables respectively, and the displacement and acceleration response of the system

  14. Development of Flexural Vibration Inspection Techniques to Rapidly

    E-print Network

    Minnesota, University of

    information for using forced vibration as a structural health monitoring and control system. #12;Project TaskDevelopment of Flexural Vibration Inspection Techniques to Rapidly Assess the Structural Health procedures for structural health monitoring of timber bridges? #12;Dynamic Response of Systems

  15. Application of the integrating fiber optic sensor for vibration monitoring

    Microsoft Academic Search

    Lei Han; A. Voloshin; J. Coulter

    1995-01-01

    Fiber optic sensors (FOS) for vibration monitoring of smart structures have certain advantages over conventional strain gage based sensors due to electromagnetic environment insensitivity and high response bandwidth. During the present study, a spatially integrating fiber optic sensor was used for vibration monitoring. It is based on the concept that the optimal placement of the sensing element can be sought

  16. Vibration monitoring by a spatially integrating fiber optic sensor

    Microsoft Academic Search

    Arkady S. Voloshin; Lei Han; John P. Coulter

    1995-01-01

    Fiber optic sensors (FOS) for vibration monitoring of smart structures have certain advantages over conventional strain gage based sensors due to electromagnetic environment insensitivity and high response bandwidth. During the present study, a spatially integrating fiber optic sensor was used for vibration monitoring. It is based on the concept that the optimal placement of the sensing element can be sought

  17. A Summary Review of Vibration-Based Damage Identification Methods

    Microsoft Academic Search

    Scott W. Doebling; Charles R. Farrar; Michael B. Prime

    1998-01-01

    This paper provides an overview of methods to detect, locate, and characterize damage in structural and mechanical systems by examining changes in measured vibration response. Research in vibration-based damage identification has been rapidly expanding over the last few years. The basic idea behind this technology is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the

  18. Random Vibrations: Assessment of the State of the Art

    SciTech Connect

    Paez, T.L.

    1999-02-23

    Random vibration is the phenomenon wherein random excitation applied to a mechanical system induces random response. We summarize the state of the art in random vibration analysis and testing, commenting on history, linear and nonlinear analysis, the analysis of large-scale systems, and probabilistic structural testing.

  19. Analytical and experimental investigations on vibrational control mechanisms for flexible active structures

    NASA Astrophysics Data System (ADS)

    Lin, R. M.; Nyang, K. M.

    2003-06-01

    The study of smart structures with active devices of sensors and actuators for self-monitoring and self-adaption has been of much recent research interest. Active vibrational control is a major application focus and there has been a tremendous amount of research work on active vibrational control of flexible structures using piezoelectric materials. In this paper, the control mechanism for a flexible cantilever plate structure using surface-bonded piezoelectric sensors and actuators has been studied through analytical simulations and experiments. The sensor outputs were used to determine the amount of input to the actuators for controlling the response of the structure in a closed loop. The responses under different control mechanisms were analysed by a three-dimensional finite element model. The effectiveness of different feedback control methods in altering system characteristics and system responses of the structure was investigated. Experimental investigations on active vibrational control were also conducted on a cantilever plate with surface-bonded piezoelectric sensors and actuators.

  20. Primary mirror dynamic disturbance models for TMT: vibration and wind

    NASA Astrophysics Data System (ADS)

    MacMynowski, Douglas G.; Colavita, M. Mark; Skidmore, Warren; Vogiatzis, Konstantinos

    2010-07-01

    The principal dynamic disturbances acting on a telescope segmented primary mirror are unsteady wind pressure (turbulence) and narrowband vibration from rotating equipment. Understanding these disturbances is essential for the design of the segment support assembly (SSA), segment actuators, and primary mirror control system (M1CS). The wind disturbance is relatively low frequency, and is partially compensated by M1CS; the response depends on the control bandwidth and the quasi-static stiffness of the actuator and SSA. Equipment vibration is at frequencies higher than the M1CS bandwidth; the response depends on segment damping, and the proximity of segment support resonances to dominant vibration tones. We present here both disturbance models and parametric response. Wind modeling is informed by CFD and based on propagation of a von Karman pressure screen. The vibration model is informed by analysis of accelerometer and adaptive optics data from Keck. This information is extrapolated to TMT and applied to the telescope structural model to understand the response dependence on actuator design parameters in particular. Whether the vibration response or the wind response is larger depends on these design choices; "soft" (e.g. voice-coil) actuators provide better vibration reduction but require high servo bandwidth for wind rejection, while "hard" (e.g. piezo-electric) actuators provide good wind rejection but require damping to avoid excessive vibration transmission to the primary mirror segments. The results for both nominal and worst-case disturbances and design parameters are incorporated into the TMT actuator performance assessment.

  1. Response-habits and cognitive style: subject characteristics as a function of their, and their parents', drinking habits, weights, and cigarette smoking 

    E-print Network

    Barto, Scott Michael

    1980-01-01

    RESPONSE-HABITS AND COGNITIVE STYLE: SUBJECT CHARACTERISTICS AS A FUNCTION OF THEIR, AND THEIR PARENTS', DRINKING HABITS, WEIGHTS, AND CIGARETTE SMOKING A Thesis by SCOTT MICHAEL BARTO Submitted to the Graduate College of Texas A...' WEIGHTS, AND CIGARETTE SMOKING A Thesis by SCOTT MICHAEL BARTO Approved as to style and content by: (Chairman of Committee) (Member) (Member) (Member) (Head of Department) May 1980 ABSTRACT Response-Habits and Cognitive Style: Subject...

  2. Method of Green's function of nonlinear vibration of corrugated shallow shells

    NASA Astrophysics Data System (ADS)

    Yuan, Hong

    2008-06-01

    Based on the dynamic equations of nonlinear large deflection of axisymmetric shallow shells of revolution, the nonlinear free vibration and forced vibration of a corrugated shallow shell under concentrated load acting at the center have been investigated. The nonlinear partial differential equations of shallow shell were reduced to the nonlinear integral-differential equations by using the method of Green’s function. To solve the integral-differential equations, the expansion method was used to obtain Green’s function. Then the integral-differential equations were reduced to the form with a degenerate core by expanding Green’s function as a series of characteristic function. Therefore, the integral-differential equations became nonlinear ordinary differential equations with regard to time. The amplitude-frequency relation, with respect to the natural frequency of the lowest order and the amplitude-frequency response under harmonic force, were obtained by considering single mode vibration. As a numerical example, nonlinear free and forced vibration phenomena of shallow spherical shells with sinusoidal corrugation were studied. The obtained solutions are available for reference to the design of corrugated shells.

  3. Single-crystal-material-based induced-shear actuation for vibration reduction of helicopters with composite rotor system

    NASA Astrophysics Data System (ADS)

    Pawar, Prashant M.; Jung, Sung Nam

    2008-12-01

    In this study, an assessment is made for the helicopter vibration reduction of composite rotor blades using an active twist control concept. Special focus is given to the feasibility of implementing the benefits of the shear actuation mechanism along with elastic couplings of composite blades for achieving maximum vibration reduction. The governing equations of motion for composite rotor blades with surface bonded piezoceramic actuators are obtained using Hamilton's principle. The equations are then solved for dynamic response using finite element discretization in the spatial and time domains. A time domain unsteady aerodynamic theory with free wake model is used to obtain the airloads. A newly developed single-crystal piezoceramic material is introduced as an actuator material to exploit its superior shear actuation authority. Seven rotor blades with different elastic couplings representing stiffness properties similar to stiff-in-plane rotor blades are used to investigate the hub vibration characteristics. The rotor blades are modeled as a box beam with actuator layers bonded on the outer surface of the top and bottom of the box section. Numerical results show that a notable vibration reduction can be achieved for all the combinations of composite rotor blades. This investigation also brings out the effect of different elastic couplings on various vibration-reduction-related parameters which could be useful for the optimal design of composite helicopter blades.

  4. Experimental investigation on flow-induced vibration excitation in an elastically mounted circular cylinder in cylinder arrays

    NASA Astrophysics Data System (ADS)

    Karthik Selvakumar, K.; Kumaraswamidhas, L. A.

    2015-02-01

    An experimental investigation was performed in a low-speed wind tunnel in which an elastically mounted circular cylinder was fitted with two accelerometers and surrounded by from one to six identical cylinders in order to study the fluid flow characteristics and predict the possibility of suppressing flow-induced vibration excitation in the test cylinder. The spectral diagram, amplitude and orbital motion of the test cylinder were used to analyze the vibration excitation under differing free stream velocities, natural frequencies of the test cylinder, and number of surrounding cylinders. In this study, for the test cylinder with the same natural frequency as the adjacent cylinders (24 Hz) the amplitude response showed that when the fluid flow velocity exceeded a critical value, which depends on the arrangement of the cylinders, fluid elastic instability occurred. Beyond the critical velocity the cylinder became excited and vibrated in a figure-of-eight pattern along with the line-dominated spectrum, which implies that by having the same frequency along with a phase shift, the characteristic behavior of the cylinder is observed to be like an oscillator with the cross-wise and stream-wise response. From the assessment of the amplitude response of the test cylinder it was observed that the upstream cylinders had a greater influence on the amplitude response than the downstream cylinders. On the other hand, when the test cylinder had a natural frequency different to the adjacent cylinders it was observed that the frequency had a minimal effect on the critical velocity, and yet beyond the critical velocity it had a significant influence on the vibration amplitude response.

  5. An experimental study of vibration based energy harvesting in dynamically tailored structures with embedded acoustic black holes

    NASA Astrophysics Data System (ADS)

    Zhao, Liuxian; Conlon, Stephen C.; Semperlotti, Fabio

    2015-06-01

    In this paper, we present an experimental investigation on the energy harvesting performance of dynamically tailored structures based on the concept of embedded acoustic black holes (ABHs). Embedded ABHs allow tailoring the wave propagation characteristics of the host structure creating structural areas with extreme levels of energy density. Experiments are conducted on a tapered plate-like aluminum structure with multiple embedded ABH features. The dynamic response of the structure is tested via laser vibrometry in order to confirm the vibration localization and the passive wavelength sweep characteristic of ABH embedded tapers. Vibrational energy is extracted from the host structure and converted into electrical energy by using ceramic piezoelectric discs bonded on the ABHs and shunted on an external electric circuit. The energy harvesting performance is investigated both under steady state and transient excitation. The experimental results confirm that the dynamic tailoring produces a drastic increase in the harvested energy independently from the nature of the excitation input.

  6. Free vibrations of thin-walled semicircular graphite-epoxy composite frames

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Carden, Huey D.; Peters, Jeanne M.

    1990-01-01

    A detailed study is made of the effects of variations in lamination and material parameters of thin walled composite frames on their vibrational characteristics. The structures considered are semicircular thin walled frames with I and J sections. The flanges and webs of the frames are modelled by using 2-D shell and plate finite elements. A mixed formulation is used with the fundamental unknowns consisting of both the generalized displacements and stress resultants in the frames. The frequencies and modes predicted by the 2-D finite element model are compared with those obtained from experiments, as well as with the predictions of a 1-D thin walled beam finite element model. A detailed study is made of the sensitivity of the vibrational response to variations in the fiber orientation, material properties of the individual layers, and boundary conditions.

  7. Mathematical Modeling of Wear Characteristics of 6061 Al-Alloy-SiCp Composite Using Response Surface Methodology

    NASA Astrophysics Data System (ADS)

    Mandal, Nilrudra; Roy, H.; Mondal, B.; Murmu, N. C.; Mukhopadhyay, S. K.

    2012-01-01

    In the light of attractive wear characteristics as well as high strength to weight ratio, extensive research on Al-based Metal Matrix Composite (MMC) have been carried out globally in the last two decades. However, very limited research has been pursued on tribological behavior of Al-based MMC under combined action of rolling and sliding. This study investigates the wear behavior of 6061 Al-alloy/SiC with 10 vol.% SiCp against hardened and tempered AISI 4340 steel under combined rolling-sliding conditions. 23 factorial design of experiments have been carried out to see the effect of few parameters, i.e., contact stress, speed and duration with respect to wear. The interaction effect has also been studied by 3D graphical contours. A mathematical model is developed using regression analysis technique for prediction of wear behavior of the MMC and adequacy of the model has been validated using analysis of variance (ANOVA) techniques. Finally, the optimization of parameter has also been done using Design Expert software. The results have shown that Response Surface Methodology (RSM) is an effective tool for prediction of wear behavior under combined sliding and rolling action. It is also found that the wear of MMC is much lower than hardened; tempered AISI 4340 steel and rolling speed has the maximum influence in wear of both materials under investigation.

  8. Characteristics of Neoclassical Toroidal Viscosity in NSTX and KSTAR for Rotation Control and the Evaluation of Plasma Response

    NASA Astrophysics Data System (ADS)

    Sabbagh, S. A.; Berkery, J. W.; Park, Y. S.; Bell, R. E.; Gates, D. A.; Gerhardt, S. P.; Goumiri, I.; Evans, T. E.; Ferraro, N.; Jeon, Y. M.; Ko, W.; Shaing, K. C.; Sun, Y.

    2014-10-01

    Three-dimensional magnetic fields producing non-resonant magnetic braking allow control of the plasma rotation profile, ??, in tokamaks. Experimental angular momentum alteration created by 3D field configurations with dominant n = 2 and n = 3 components in NSTX is compared to theoretical neoclassical toroidal viscosity (NTV) torque density profiles, TNTV. Large radial variations of TNTV are typically found when flux surface displacements are computed using ideal MHD assumptions. In contrast, experimentally measured TNTV does not show strong torque localization. This may be explained by ion banana width orbit-averaging effects. A favorable characteristic for ?? control clearly illustrated by KSTAR experiments is the lack of hysteresis of ?? when altered by non-resonant NTV. Results from a model-based rotation controller designed using NBI and NTV from the applied 3D field as actuators are shown. The dependence of TNTV on ?B2 significantly constrains the allowable field amplification in plasma response models when compared to experiment. Initial analysis shows that the single fluid model in the M3D-C1 resistive MHD code produces a flux surface-averaged ?B consistent with the experimentally measured TNTV. Supported by US DOE Contracts DE-FG02-99ER54524 and DE-AC02-09CH11466.

  9. Analyses of Nematic Liquid Crystal Molecule Motion and Response Characteristics in Microstripline-Type Microwave Phase Shifter

    NASA Astrophysics Data System (ADS)

    Nguyen, Thanh; Thanh Nguyen, Bach; Ozaki, Ryotaro; Moritake, Hiroshi

    2013-12-01

    In this paper, we propose an improved calculation method for analyzing the three-dimensional motion of nematic liquid crystal molecules in studies of all types of microwave transmission line loaded with a nematic liquid crystal. This method is applied to the analysis of motion of nematic liquid crystal molecules under a nonuniformly distributed electric field generated by asymmetric electrodes in a microstripline structure as a comprehensive example. Then, the dielectric constant distribution of the nematic liquid crystal layer, the effective dielectric constant in a microwave electric field, and the phase shift of a microwave in the microstripline loaded with a nematic liquid crystal are calculated. The rise time, decay time, and phase shift of a microwave phase shifter using a microstripline loaded with a nematic liquid crystal are also calculated. The differences in these response characteristics and their dependences on the width of the center conductor of the microstripline are determined by calculation and confirmed by performing experiments on the microwave phase shifters and an optical experiment on the retardation of the microstripline loaded with a nematic liquid crystal structure.

  10. Multi axes vibration fixtures

    NASA Technical Reports Server (NTRS)

    Sims, C. R. (inventor); Taylor, R. C.

    1973-01-01

    A simplified technique and apparatus are described for testing the effects of vibration on various material specimen. Particular attention was given to tests along the orthogonal vibrational planes in order to prove the strength of the item under extraordinary conditions to which it will be subjected.

  11. Foundation Vibration Isolation Methods

    Microsoft Academic Search

    ASHWANI JAIN; D. K. SONI

    2007-01-01

    All machine foundations except very small ones should be regarded as engineering problem to be dealt with cautiously. The larger ones give rise to enormous dynamic loads, causing vibrations, which the designer must take into account. Care must be taken to ensure smooth running of machine by avoiding harmful vibrations in the base or in the sub-soil or if the

  12. Multiple direction vibration fixture

    DOEpatents

    Cericola, Fred (Albuquerque, NM); Doggett, James W. (Albuquerque, NM); Ernest, Terry L. (Albuquerque, NM); Priddy, Tommy G. (Rockville, MD)

    1991-01-01

    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.

  13. DOWNHOLE VIBRATION MONITORING AND CONTROL SYSTEM

    SciTech Connect

    Martin E. Cobern

    2003-02-01

    The purpose of this program is to develop the Drilling Vibration Monitoring & Control System (DVMCS) to both record and reduce drilling vibrations in a ''smart'' drill string. It is composed of two main elements. The first is a multi-axis active vibration damper to minimize harmful axial, lateral and torsional vibrations, and thereby increase both rate of penetration (ROP) and bit life, as well that the life of other drillstring components. The hydraulic impedance (hardness) of this damper will be continuously adjusted using unique technology that is robust, fast-acting and reliable. The second component is a real-time system to monitor 3-axis drillstring vibration, and related parameters including weight- and torque-on-bit (TOB) and temperature. This monitor will determine the current vibration environment and adjust the damper accordingly. In some configurations, it may also send diagnostic information to the surface via real-time telemetry. Phase I of this program addresses an evaluation of the environment in which the DVMCS will operate; modeling of a drillstring response including the active damper; a top-level design of the mechanical and electronic systems; analyzing the anticipated performance of the damper by modeling and laboratory testing of small prototypes; and doing preliminary economic, market, environmental and financing analyses. This phase is scheduled to last fourteen months, until November 30, 2003. During this first quarter, significant progress was achieved on the first two objectives, and work was begun on several others. Initial designs of the DVMCS are underway.

  14. Prediction of Ground Vibration from Freight Trains

    NASA Astrophysics Data System (ADS)

    Jones, C. J. C.; Block, J. R.

    1996-05-01

    Heavy freight trains emit ground vibration with predominant frequency components in the range 4-30 Hz. If the amplitude is sufficient, this may be felt by lineside residents, giving rise to disturbance and concern over possible damage to their property. In order to establish the influence of parameters of the track and rolling stock and thereby enable the design of a low vibration railway, a theoretical model of both the generation and propagation of vibration is required. The vibration is generated as a combination of the effects of dynamic forces, due to the unevenness of the track, and the effects of the track deformation under successive axle loads. A prediction scheme, which combines these effects, has been produced. A vehicle model is used to predict the dynamic forces at the wheels. This includes the non-linear effects of friction damped suspensions. The loaded track profile is measured by using a track recording coach. The dynamic loading and the effects of the moving axles are combined in a track response model. The predicted track vibration is compared to measurements. The transfer functions from the track to a point in the ground can be calculated by using a coupled track and a three-dimensional layered ground model. The propagation effects of the ground layers are important but the computation of the transfer function from each sleeper, which would be required for a phase coherent summation of the vibration in the ground, would be prohibitive. A compromise summation is used and results are compared with measurements.

  15. Vibrational spectroscopy in the electron microscope

    NASA Astrophysics Data System (ADS)

    Krivanek, Ondrej L.; Lovejoy, Tracy C.; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R. W.; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E.; Lagos, Maureen J.; Egerton, Ray F.; Crozier, Peter A.

    2014-10-01

    Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for `aloof' spectroscopy that largely avoids radiation damage.

  16. Vibrational spectroscopy in the electron microscope.

    PubMed

    Krivanek, Ondrej L; Lovejoy, Tracy C; Dellby, Niklas; Aoki, Toshihiro; Carpenter, R W; Rez, Peter; Soignard, Emmanuel; Zhu, Jiangtao; Batson, Philip E; Lagos, Maureen J; Egerton, Ray F; Crozier, Peter A

    2014-10-01

    Vibrational spectroscopies using infrared radiation, Raman scattering, neutrons, low-energy electrons and inelastic electron tunnelling are powerful techniques that can analyse bonding arrangements, identify chemical compounds and probe many other important properties of materials. The spatial resolution of these spectroscopies is typically one micrometre or more, although it can reach a few tens of nanometres or even a few ångströms when enhanced by the presence of a sharp metallic tip. If vibrational spectroscopy could be combined with the spatial resolution and flexibility of the transmission electron microscope, it would open up the study of vibrational modes in many different types of nanostructures. Unfortunately, the energy resolution of electron energy loss spectroscopy performed in the electron microscope has until now been too poor to allow such a combination. Recent developments that have improved the attainable energy resolution of electron energy loss spectroscopy in a scanning transmission electron microscope to around ten millielectronvolts now allow vibrational spectroscopy to be carried out in the electron microscope. Here we describe the innovations responsible for the progress, and present examples of applications in inorganic and organic materials, including the detection of hydrogen. We also demonstrate that the vibrational signal has both high- and low-spatial-resolution components, that the first component can be used to map vibrational features at nanometre-level resolution, and that the second component can be used for analysis carried out with the beam positioned just outside the sample--that is, for 'aloof' spectroscopy that largely avoids radiation damage. PMID:25297434

  17. Male courtship vibrations delay predatory behaviour in female spiders

    PubMed Central

    Wignall, Anne E.; Herberstein, Marie E.

    2013-01-01

    During courtship, individuals transfer information about identity, mating status and quality. However, male web-building spiders face a significant problem: how to begin courting female spiders without being mistaken for prey? Male Argiope spiders generate distinctive courtship vibrations (shudders) when entering a female's web. We tested whether courtship shudders delay female predatory behaviour, even when live prey is present in the web. We presented a live cricket to females during playbacks of shudder vibrations, or white noise, and compared female responses to a control in which we presented a live cricket with no playback vibrations. Females were much slower to respond to crickets during playback of shudder vibrations. Shudder vibrations also delayed female predatory behaviour in a related spider species, showing that these vibrations do not simply function for species identity. These results suggest that male web-building spiders employ a phylogenetically conserved vibratory signal to ameliorate the risk of pre-copulatory cannibalism. PMID:24356181

  18. Male courtship vibrations delay predatory behaviour in female spiders.

    PubMed

    Wignall, Anne E; Herberstein, Marie E

    2013-01-01

    During courtship, individuals transfer information about identity, mating status and quality. However, male web-building spiders face a significant problem: how to begin courting female spiders without being mistaken for prey? Male Argiope spiders generate distinctive courtship vibrations (shudders) when entering a female's web. We tested whether courtship shudders delay female predatory behaviour, even when live prey is present in the web. We presented a live cricket to females during playbacks of shudder vibrations, or white noise, and compared female responses to a control in which we presented a live cricket with no playback vibrations. Females were much slower to respond to crickets during playback of shudder vibrations. Shudder vibrations also delayed female predatory behaviour in a related spider species, showing that these vibrations do not simply function for species identity. These results suggest that male web-building spiders employ a phylogenetically conserved vibratory signal to ameliorate the risk of pre-copulatory cannibalism. PMID:24356181

  19. Vibration Harvesting using Electromagnetic Transduction

    E-print Network

    Waterbury, Andrew

    2011-01-01

    asset monitoring or tracking where the vibrations from themonitoring. Further investigation into characterizing industrial vibrationmonitoring 6.1. Large industrial motor deployment 6.1.1. Motor vibration

  20. Vibration isolating engine mount

    NASA Astrophysics Data System (ADS)

    Bender, Stanley I.; Dawes, Peter W.; Butler, Lawrence

    1993-07-01

    An improved engine suspension system is provided for attenuating vibration in a gas turbine engine. In one embodiment, the invention is directed to an aircraft engine suspension system for mounting a gas turbine engine to a supporting frame by mounts arranged in first and second parallel, spaced axial mounting planes of the engine. First and second vibration isolation mounts are aligned in the first mounting plane and couple the engine to the supporting frame. Each of the first and second mounts provides both radial and axial vibration damping to the engine as well as radial and axial stiffness. A third vibration isolation mount is aligned in the second mounting plane and couples the engine and support frame together to provide radial and tangential vibration damping to the engine as well as radial and tangential stiffness. The mounts are arranged axially and radially such that the suspension system is statically and dynamically determinate.