WorldWideScience

Sample records for random vibration testing

  1. Random vibration test of Mars Exploration Rover spacecraft

    Science.gov (United States)

    Scharton, T.; Lee, D.

    2003-01-01

    The primary objective of the random vibration test was to identify any hardware problems, which might compromise the mission. The test objectives, configuration, and requirements are briefly described in this presentation, and a representative sample of the measured data is presented.

  2. Force Limited Random Vibration Test of TESS Camera Mass Model

    Science.gov (United States)

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

    2015-01-01

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

  3. Random Vibration Testing of Advanced Wet Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2015-01-01

    Advanced wet tantalum capacitors allow for improved performance of power supply systems along with substantial reduction of size and weight of the systems that is especially beneficial for space electronics. Due to launch-related stresses, acceptance testing of all space systems includes random vibration test (RVT). However, many types of advanced wet tantalum capacitors cannot pass consistently RVT at conditions specified in MIL-PRF-39006, which impedes their use in space projects. This requires a closer look at the existing requirements, modes and mechanisms of failures, specifics of test conditions, and acceptance criteria. In this work, different lots of advanced wet tantalum capacitors from four manufacturers have been tested at step stress random vibration conditions while their currents were monitored before, during, and after the testing. It has been shown that the robustness of the parts and their reliability are mostly due to effective self-healing processes and limited current spiking or minor scintillations caused by RVT do not increase the risk of failures during operation. A simple model for scintillations events has been used to simulate current spiking during RVT and optimize test conditions. The significance of scintillations and possible effects of gas generation have been discussed and test acceptance criteria for limited current spiking have been suggested.

  4. Experimental Design and Validation of an Accelerated Random Vibration Fatigue Testing Methodology

    OpenAIRE

    Yu Jiang(Center for Statistical and Theoretical Condensed Matter Physics, Zhejiang Normal University, Jinhua City, Zhejiang Province 321004, China); Gun Jin Yun; Li Zhao; Junyong Tao

    2015-01-01

    Novel accelerated random vibration fatigue test methodology and strategy are proposed, which can generate a design of the experimental test plan significantly reducing the test time and the sample size. Based on theoretical analysis and fatigue damage model, several groups of random vibration fatigue tests were designed and conducted with the aim of investigating effects of both Gaussian and non-Gaussian random excitation on the vibration fatigue. First, stress responses at a weak point of a ...

  5. A new compound control method for sine-on-random mixed vibration test

    Science.gov (United States)

    Zhang, Buyun; Wang, Ruochen; Zeng, Falin

    2017-09-01

    Vibration environmental test (VET) is one of the important and effective methods to provide supports for the strength design, reliability and durability test of mechanical products. A new separation control strategy was proposed to apply in multiple-input multiple-output (MIMO) sine on random (SOR) mixed mode vibration test, which is the advanced and intensive test type of VET. As the key problem of the strategy, correlation integral method was applied to separate the mixed signals which included random and sinusoidal components. The feedback control formula of MIMO linear random vibration system was systematically deduced in frequency domain, and Jacobi control algorithm was proposed in view of the elements, such as self-spectrum, coherence, and phase of power spectral density (PSD) matrix. Based on the excessive correction of excitation in sine vibration test, compression factor was introduced to reduce the excitation correction, avoiding the destruction to vibration table or other devices. The two methods were synthesized to be applied in MIMO SOR vibration test system. In the final, verification test system with the vibration of a cantilever beam as the control object was established to verify the reliability and effectiveness of the methods proposed in the paper. The test results show that the exceeding values can be controlled in the tolerance range of references accurately, and the method can supply theory and application supports for mechanical engineering.

  6. Force limited random vibration testing: the computation of the semi-empirical constant C2 for a real test article and unknown supporting structure

    NARCIS (Netherlands)

    Wijker, Jacob J; Ellenbroek, Marcellinus Hermannus Maria; de Boer, Andries

    2015-01-01

    To prevent over-testing of the test-item during random vibration testing Scharton proposed and discussed the force limited random vibration testing (FLVT) in a number of publications. Besides the random vibration specification, the total mass and the turn-over frequency of the test article (load),

  7. A Procedure for Accurately Measuring the Shaker Overturning Moment During Random Vibration Tests

    Science.gov (United States)

    Nayeri, Reza D.

    2011-01-01

    Motivation: For large system level random vibration tests, there may be some concerns about the shaker's capability for the overturning moment. It is the test conductor's responsibility to predict and monitor the overturning moment during random vibration tests. If the predicted moment is close to the shaker's capability, test conductor must measure the instantaneous moment at low levels and extrapolate to higher levels. That data will be used to decide whether it is safe to proceed to the next test level. Challenge: Kistler analog formulation for computing the real-time moment is only applicable to very limited cases in which we have 3 or 4 load cells installed at shaker interface with hardware. Approach: To overcome that limitation, a simple procedure was developed for computing the overturning moment time histories using the measured time histories of the individual load cells.

  8. Correlation of finite element free vibration predictions using random vibration test data. M.S. Thesis - Cleveland State Univ.

    Science.gov (United States)

    Chambers, Jeffrey A.

    1994-01-01

    Finite element analysis is regularly used during the engineering cycle of mechanical systems to predict the response to static, thermal, and dynamic loads. The finite element model (FEM) used to represent the system is often correlated with physical test results to determine the validity of analytical results provided. Results from dynamic testing provide one means for performing this correlation. One of the most common methods of measuring accuracy is by classical modal testing, whereby vibratory mode shapes are compared to mode shapes provided by finite element analysis. The degree of correlation between the test and analytical mode shapes can be shown mathematically using the cross orthogonality check. A great deal of time and effort can be exhausted in generating the set of test acquired mode shapes needed for the cross orthogonality check. In most situations response data from vibration tests are digitally processed to generate the mode shapes from a combination of modal parameters, forcing functions, and recorded response data. An alternate method is proposed in which the same correlation of analytical and test acquired mode shapes can be achieved without conducting the modal survey. Instead a procedure is detailed in which a minimum of test information, specifically the acceleration response data from a random vibration test, is used to generate a set of equivalent local accelerations to be applied to the reduced analytical model at discrete points corresponding to the test measurement locations. The static solution of the analytical model then produces a set of deformations that once normalized can be used to represent the test acquired mode shapes in the cross orthogonality relation. The method proposed has been shown to provide accurate results for both a simple analytical model as well as a complex space flight structure.

  9. Research on the Random Shock Vibration Test Based on the Filter-X LMS Adaptive Inverse Control Algorithm

    Directory of Open Access Journals (Sweden)

    Wang Wei

    2016-01-01

    Full Text Available The related theory and algorithm of adaptive inverse control were presented through the research which pointed out the adaptive inverse control strategy could effectively eliminate the noise influence on the system control. Proposed using a frequency domain filter-X LMS adaptive inverse control algorithm, and the control algorithm was applied to the two-exciter hydraulic vibration test system of random shock vibration control process and summarized the process of the adaptive inverse control strategies in the realization of the random shock vibration test. The self-closed-loop and field test show that using the frequency-domain filter-X LMS adaptive inverse control algorithm can realize high precision control of random shock vibration test.

  10. 49 CFR 178.819 - Vibration test.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.819 Section 178.819... Testing of IBCs § 178.819 Vibration test. (a) General. The vibration test must be conducted for the... vibration test. (b) Test method. (1) A sample IBC, selected at random, must be filled and closed as for...

  11. Random vibrations theory and practice

    CERN Document Server

    Wirsching, Paul H; Ortiz, Keith

    1995-01-01

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

  12. Randomization tests

    CERN Document Server

    Edgington, Eugene

    2007-01-01

    Statistical Tests That Do Not Require Random Sampling Randomization Tests Numerical Examples Randomization Tests and Nonrandom Samples The Prevalence of Nonrandom Samples in Experiments The Irrelevance of Random Samples for the Typical Experiment Generalizing from Nonrandom Samples Intelligibility Respect for the Validity of Randomization Tests Versatility Practicality Precursors of Randomization Tests Other Applications of Permutation Tests Questions and Exercises Notes References Randomized Experiments Unique Benefits of Experiments Experimentation without Mani

  13. Force limited random vibration testing: the computation of the semi-empirical constant $C(2) $ C 2 for a real test article and unknown supporting structure

    Science.gov (United States)

    Wijker, J. J.; Ellenbroek, M. H. M.; Boer, A. de

    2015-09-01

    To prevent over-testing of the test-item during random vibration testing Scharton proposed and discussed the force limited random vibration testing (FLVT) in a number of publications. Besides the random vibration specification, the total mass and the turn-over frequency of the test article (load), C^2 is a very important parameter for FLVT. A number of computational methods to estimate C^2 are described in the literature, i.e. the simple and the complex two degree of freedom system, STDFS and CTDFS, respectively. The motivation of this work is to evaluate the method for the computation of a realistic value of C^2 to perform a representative random vibration test based on force limitation, when the description of the supporting structure (source) is more or less unknown. Marchand discussed the formal description of obtaining C^2, using the maximum PSD of the acceleration and maximum PSD of the force, both at the interface between test article and supporting structure. Stevens presented the coupled systems modal approach (CSMA), where simplified asparagus patch models (parallel-oscillator representation) of load and source are connected. The asparagus patch model consists of modal effective masses and spring stiffnesses associated with the natural frequencies. When the random acceleration vibration specification is given the CSMA method is suitable to compute the value of the parameter C^2. When no mathematical model of the source can be made available, estimations of the value C^2 can be find in literature. In this paper a probabilistic mathematical representation of the unknown source is proposed, such that the asparagus patch model of the source can be approximated. The chosen probabilistic design parameters have a uniform distribution. The computation of the value C^2 can be done in conjunction with the CSMA method, knowing the apparent mass of the load and the random acceleration specification at the interface between load and source, respectively. Data of two

  14. Benefits of Spacecraft Level Vibration Testing

    Science.gov (United States)

    Gordon, Scott; Kern, Dennis L.

    2015-01-01

    NASA-HDBK-7008 Spacecraft Level Dynamic Environments Testing discusses the approaches, benefits, dangers, and recommended practices for spacecraft level dynamic environments testing, including vibration testing. This paper discusses in additional detail the benefits and actual experiences of vibration testing spacecraft for NASA Goddard Space Flight Center (GSFC) and Jet Propulsion Laboratory (JPL) flight projects. JPL and GSFC have both similarities and differences in their spacecraft level vibration test approach: JPL uses a random vibration input and a frequency range usually starting at 5 Hz and extending to as high as 250 Hz. GSFC uses a sine sweep vibration input and a frequency range usually starting at 5 Hz and extending only to the limits of the coupled loads analysis (typically 50 to 60 Hz). However, both JPL and GSFC use force limiting to realistically notch spacecraft resonances and response (acceleration) limiting as necessary to protect spacecraft structure and hardware from exceeding design strength capabilities. Despite GSFC and JPL differences in spacecraft level vibration test approaches, both have uncovered a significant number of spacecraft design and workmanship anomalies in vibration tests. This paper will give an overview of JPL and GSFC spacecraft vibration testing approaches and provide a detailed description of spacecraft anomalies revealed.

  15. 14 CFR 33.83 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.83 Section 33.83... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.83 Vibration test. (a) Each engine must undergo vibration surveys to establish that the vibration characteristics of those components that...

  16. 14 CFR 33.43 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Vibration test. 33.43 Section 33.43... STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each engine must undergo a vibration survey to establish the torsional and bending vibration characteristics...

  17. Piezoelectric energy harvesting from broadband random vibrations

    Science.gov (United States)

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

    2009-11-01

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

  18. 49 CFR 178.985 - Vibration test.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration test. 178.985 Section 178.985... Testing of Large Packagings § 178.985 Vibration test. (a) General. All rigid Large Packaging and flexible Large Packaging design types must be capable of withstanding the vibration test. (b) Test method. (1) A...

  19. Scaling Techniques for Combustion Device Random Vibration Predictions

    Science.gov (United States)

    Kenny, R. J.; Ferebee, R. C.; Duvall, L. D.

    2016-01-01

    This work presents compares scaling techniques that can be used for prediction of combustion device component random vibration levels with excitation due to the internal combustion dynamics. Acceleration and unsteady dynamic pressure data from multiple component test programs are compared and normalized per the two scaling approaches reviewed. Two scaling technique are reviewed and compared against the collected component test data. The first technique is an existing approach developed by Barrett, and the second technique is an updated approach new to this work. Results from utilizing both techniques are presented and recommendations about future component random vibration prediction approaches are given.

  20. Probability of Failure in Random Vibration

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Sørensen, John Dalsgaard

    1988-01-01

    Close approximations to the first-passage probability of failure in random vibration can be obtained by integral equation methods. A simple relation exists between the first-passage probability density function and the distribution function for the time interval spent below a barrier before out...

  1. 33 CFR 159.103 - Vibration test.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Vibration test. 159.103 Section...) POLLUTION MARINE SANITATION DEVICES Design, Construction, and Testing § 159.103 Vibration test. The device... subjected to a sinusoidal vibration for a period of 12 hours, 4 hours in each of the x, y, and z planes, at...

  2. RANDOM VIBRATION ANALYSIS OF SANDWICH COMPOSITE BEAMS

    OpenAIRE

    K. Ravindranath Tagore, Rachumalla Pallavi

    2016-01-01

    In this thesis, a sandwich composite for Semi-monocoque construction in aircraft fuselage is analyzed for its strength under different loading conditions using different materials for Stringers balsa wood, syntactic foams, and honeycombs and Carbon Fiber reinforced thermoplastics is used as skin material. 3D modeling is done in Pro/Engineer. Static, Modal and Random Vibration analysis is done on the beam using finite element analysis software Ansys.

  3. Force limited vibration testing: an evaluation of the computation of C2 for real load and probabilistic source

    NARCIS (Netherlands)

    Wijker, Jacob J; de Boer, Andries; Ellenbroek, Marcellinus Hermannus Maria

    2015-01-01

    To prevent over-testing of the test-item during random vibration testing Scharton proposed and discussed the force limited random vibration testing (FLVT) in a number of publications. Besides the random vibration specification, the total mass and the turn-over frequency of the load (test item), is a

  4. Max Launch Abort System (MLAS) Pad Abort Test Vehicle (PATV) II Attitude Control System (ACS) Integration and Pressurization Subsystem Dynamic Random Vibration Analysis

    Science.gov (United States)

    Ekrami, Yasamin; Cook, Joseph S.

    2011-01-01

    In order to mitigate catastrophic failures on future generation space vehicles, engineers at the National Aeronautics and Space Administration have begun to integrate a novel crew abort systems that could pull a crew module away in case of an emergency at the launch pad or during ascent. The Max Launch Abort System (MLAS) is a recent test vehicle that was designed as an alternative to the baseline Orion Launch Abort System (LAS) to demonstrate the performance of a "tower-less" LAS configuration under abort conditions. The MLAS II test vehicle will execute a propulsive coast stabilization maneuver during abort to control the vehicles trajectory and thrust. To accomplish this, the spacecraft will integrate an Attitude Control System (ACS) with eight hypergolic monomethyl hydrazine liquid propulsion engines that are capable of operating in a quick pulsing mode. Two main elements of the ACS include a propellant distribution subsystem and a pressurization subsystem to regulate the flow of pressurized gas to the propellant tanks and the engines. The CAD assembly of the Attitude Control System (ACS) was configured and integrated into the Launch Abort Vehicle (LAV) design. A dynamic random vibration analysis was conducted on the Main Propulsion System (MPS) helium pressurization panels to assess the response of the panel and its components under increased gravitational acceleration loads during flight. The results indicated that the panels fundamental and natural frequencies were farther from the maximum Acceleration Spectral Density (ASD) vibrations which were in the range of 150-300 Hz. These values will direct how the components will be packaged in the vehicle to reduce the effects high gravitational loads.

  5. Investigation on random vibration of a drillstring

    Science.gov (United States)

    Qiu, Hongyuan; Yang, Jianming; Butt, Stephen; Zhong, Jinghan

    2017-10-01

    This paper investigates the axial-torsional coupled vibration of a drill-string under combined deterministic and random excitations. Finite element method (FEM) is used to model the system. The random excitation at the bit-rock interaction, which is considered in the bit axial direction, is treated as Gaussian white noise. Statistic linearization is first applied to find a equivalent linear dynamic system which is then solved with stochastic Newmark algorithm. The statistics of the responses, including the means and standard deviations of the bit axial displacement and rotational velocity are obtained and analyzed.

  6. Reliability Analysis of Random Vibration Transmission Path Systems

    Directory of Open Access Journals (Sweden)

    Wei Zhao

    2017-01-01

    Full Text Available The vibration transmission path systems are generally composed of the vibration source, the vibration transfer path, and the vibration receiving structure. The transfer path is the medium of the vibration transmission. Moreover, the randomness of transfer path influences the transfer reliability greatly. In this paper, based on the matrix calculus, the generalized second moment technique, and the stochastic finite element theory, the effective approach for the transfer reliability of vibration transfer path systems was provided. The transfer reliability of vibration transfer path system with uncertain path parameters including path mass and path stiffness was analyzed theoretically and computed numerically, and the correlated mathematical expressions were derived. Thus, it provides the theoretical foundation for the dynamic design of vibration systems in practical project, so that most random path parameters can be considered to solve the random problems for vibration transfer path systems, which can avoid the system resonance failure.

  7. Reliability Analysis of Random Vibration Transmission Path Systems

    OpenAIRE

    Wei Zhao; Yi-Min Zhang

    2017-01-01

    The vibration transmission path systems are generally composed of the vibration source, the vibration transfer path, and the vibration receiving structure. The transfer path is the medium of the vibration transmission. Moreover, the randomness of transfer path influences the transfer reliability greatly. In this paper, based on the matrix calculus, the generalized second moment technique, and the stochastic finite element theory, the effective approach for the transfer reliability of vibratio...

  8. The use of random decrement technique for identification of structural modes of vibration. [tested on a generalized payload and the space shuttle model

    Science.gov (United States)

    Ibrahim, S. R.

    1977-01-01

    An algorithm is developed to obtain the free responses of a structure from its random responses due to some unknown or known random input or inputs, using the random-decrement technique without changing time correlation between signals. The algorithm is tested using random responses from a 'generalized payload' model and from the 'Space Shuttle' model. The resulting free responses are then used to identify the modal characteristics of the two systems.

  9. High force vibration testing with wide frequency range

    Science.gov (United States)

    Romero, Edward F.; Jepsen, Richard A.; Gregory, Danny Lynn

    2013-04-02

    A shaker assembly for vibration testing includes first and second shakers, where the first shaker includes a piezo-electric material for generating vibration. A support structure permits a test object to be supported for vibration of the test object by both shakers. An input permits an external vibration controller to control vibration of the shakers.

  10. Fatigue failure of materials under narrow band random vibrations. I.

    Science.gov (United States)

    Huang, T. C.; Hubbard, R. B.; Lanz, R. W.

    1971-01-01

    A novel approach for the study of fatigue failure of materials under the multifactor influence of narrow band random vibrations is developed. The approach involves the conduction of an experiment in conjunction with various statistical techniques. Three factors including two statistical properties of the excitation or response are considered and varied simultaneously. A minimum of 6 tests for 3 variables is possible for a fractional f actorial design. The four coefficients of the predicting equation can be independently estimated. A look at 3 predicting equations shows the predominant effect of the root mean square stress of the first order equation.

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

    Science.gov (United States)

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

    2018-01-01

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

  12. Random Vibration and Torque Tests of Fasteners Secured With Locking Cable, Room Temperature Vulcanized (RTV) Rubber, and Closed Cell Foam to Support the Launch of STS-82

    Science.gov (United States)

    Yost, V. H.

    1997-01-01

    During a walkdown of the Space Transportation System (STS) orbiter for the 82nd Space Shuttle flight (STS-82), technicians found several safety cables for bolts with missing or loose ferrules. Typically, two or three bolts are secured with a cable which passes through one of the holes in the head of each bolt and a ferrule is crimped on each end of the cable to prevent it from coming out of the holes. The purpose of the cable is to prevent bolts from rotating should they become untightened. Other bolts are secured with either a locking cable or wire which is covered with RTV and foam. The RTV and foam would have to be removed to inspect for missing or loose ferrules. To determine whether this was necessary, vibration and torque test fixtures and tests were made to determine whether or not bolts with missing or loose ferrules would unloosen. These tests showed they would not, and the RTV and foam was not removed.

  13. Experimental Research on Vibration Fatigue of CFRP and Its Influence Factors Based on Vibration Testing

    OpenAIRE

    Fan, Zhengwei; Jiang, Yu; Zhang, Shufeng; Chen, Xun

    2017-01-01

    A new research method based on vibration testing for the vibration fatigue of FRP was proposed in this paper. Through the testing on a closed-loop controlled vibration fatigue test system, the vibration fatigue phenomenon of typical carbon-fiber-reinforced plastic (CFRP) cantilevered laminate specimens was carefully studied. Moreover, a method based on the frequency response function was proposed to monitor the fatigue damage accumulation of specimens. On the basis of that, the influence fact...

  14. The Shock Vibration Bulletin. Part 3. Isolation and Damping, Vibration Test Criteria, and Vibration Analysis and Test

    Science.gov (United States)

    1987-01-01

    fatigae equivalent test time of 45-mimates. 1. BACKGROUND subjected to both vibration and loose cargo testing as well an the type and amount of...Environmental Test the track laying environment. Nethods, 10 March 1975. 8. FUTURE EFFORTS 11. Soci, Darrell F., Fatigae Life Estimation Techniques, Technical

  15. Some heuristic procedures for analyzing random vibration of nonlinear oscillators.

    Science.gov (United States)

    Crandall, S. H.

    1971-01-01

    The stationary response of a lightly damped nonlinear oscillator subjected to wideband random excitation can be examined as an example of thermal equilibrium. It may be assumed that the response consists of a series of free-vibration cycles with small random fluctuations in phase and amplitude. Certain statistical properties of the response can be estimated by averaging corresponding properties of the free vibration with respect to cycle amplitude distributions. Such heuristic procedures for determining the expected frequency and the autocorrelation function of the stationary response are outlined. Some additional results concerning first-passage problems for nonlinear oscillators are included.

  16. 46 CFR 162.050-37 - Vibration test.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 6 2010-10-01 2010-10-01 false Vibration test. 162.050-37 Section 162.050-37 Shipping...: SPECIFICATIONS AND APPROVAL ENGINEERING EQUIPMENT Pollution Prevention Equipment § 162.050-37 Vibration test. (a... and each control of a separator must be subjected to continuous sinusoidal vibration in each of the...

  17. Vibrations in glasses and Euclidean random matrix theory

    Energy Technology Data Exchange (ETDEWEB)

    Grigera, T.S.; Martin-Mayor, V.; Parisi, G. [Dipartimento di Fisica, Universita di Roma ' La Sapienza' , Rome (Italy); INFN Sezione di Roma - INFM Unita di Roma, Rome (Italy); Verrocchio, P. [Dipartimento di Fisica, Universita di Trento, Povo, Trento (Italy); INFM Unita di Trento, Trento (Italy)

    2002-03-11

    We study numerically and analytically a simple off-lattice model of scalar harmonic vibrations by means of Euclidean random matrix theory. Since the spectrum of this model shares the most puzzling spectral features with the high-frequency domain of glasses (non-Rayleigh broadening of the Brillouin peak, boson peak and secondary peak), Euclidean random matrix theory provides a single and fairly simple theoretical framework for their explanation. (author)

  18. Sound insulation and vibration tests for lightweight steel framing floors

    OpenAIRE

    Shi, Wanqing; Edfast, Fredrik; Ågren, Anders

    2000-01-01

    An experimental study of sound insulation and vibrations of lightweight steel framing floors due to different floor construction set up were performed. Floors with 3m, 5m and 7.2m span were tested. The impact and airborne sound insulation for 3m span floor were measured based on ISO 140 in lab condition. Vibration tests were carried out on all three different spans. The vibration transmission loss of the structure was determined from the surface vibration measurements. The fundamental natural...

  19. Comparison of a Vibrating Foam Roller and a Non-vibrating Foam Roller Intervention on Knee Range of Motion and Pressure Pain Threshold: A Randomized Controlled Trial.

    Science.gov (United States)

    Cheatham, Scott W; Stull, Kyle R; Kolber, Morey J

    2017-08-08

    The use of foam rollers to provide soft-tissue massage has become a common intervention among health and fitness professionals. Recently, manufacturers have merged the science of vibration therapy and foam rolling with the development of vibrating foam rollers. To date, no peer reviewed investigations have been published on this technology. The purpose of this study was to compare the effects of a vibrating roller and non-vibrating roller intervention on prone knee flexion passive range of motion (ROM) and pressure pain thresholds (PPT) of the quadriceps musculature. Forty-five recreationally active adults were randomly allocated to one of three groups: vibrating roller, non-vibrating roller, and control. Each roll intervention lasted a total of 2 minutes. The control group did not roll. Dependent variables included prone knee flexion ROM and PPT measures. Statistical analysis included parametric and non-parametric tests to measure changes among groups. The vibrating roller demonstrated the greatest increase in PPT (180kPa, p< 0.001), followed by the non-vibrating roller (112kPa, p< 0.001), and control (61kPa, p<0.001). For knee ROM, the vibrating roller demonstrated the greatest increase in ROM (7 degrees, p< 0.001), followed by the non-vibrating roller (5 degrees, p< 0.001), and control (2 degrees, p<0.001). Between groups, there was significant difference in PPT between the vibrating and non-vibrating roller (p=.03) and vibrating roller and control (p<.001). There was also a significant difference between the non-vibrating roller and control (p<.001). For knee ROM, there was no significant difference between the vibrating and non-vibrating roller (p=.31). A significant difference was found between the vibrating roller and control group (p<.001) and non-vibrating roller and control (p<.001). The results suggest that a vibrating roller may increase an individual's tolerance to pain greater than a non-vibrating roller. This investigation should be considered

  20. Ambient Vibration Test on Reinforced Concrete Bridges

    Directory of Open Access Journals (Sweden)

    Idris Nurul Shazwin

    2016-01-01

    Full Text Available An investigation was carried out to determine dynamic characteristic of reinforced concrete (RC bridges by using ambient vibration test (AVT. The ambient vibration sources on bridges may come from traffic, wind, wave motion and seismic events. AVT describes the dynamic characteristics of the bridge and ground by measuring the natural frequencies using highly sensitive seismometer sensor. This test is beneficial due to light weight equipment and smaller number of operator required, cheap and easy to be handled. It is able to give a true picture of the bridge dynamic behavior without any artificial force excitation when vibration data is recorded. A three-span reinforced concrete bridge located in Sri Medan, Batu Pahat, Johor was measured by using microtremor equipment consist of three units of 1 Hz eigenfrequency passive sensors used in this test was performed in normal operating condition without excitation required from any active sources or short period noise perturbations. Ten measurements were conducted on the bridge deck and ten measurements on the ground surface in order to identify the natural frequencies of the bridge. Several peak frequencies were identified from three components of Fourier Amplitude Spectra (FAS in transverse (North-South, longitudinal (East-West and vertical (Up-Down direction as well as squared average Horizontal to Vertical Spectral Ratio (HVSR of ground response, computed by using Geopsy software. From the result, it was expected the bridge have five vibration modes frequencies in the range of 1.0 Hz and 7.0 Hz with the first two modes in the transverse and longitudinal direction having a frequency 1.0 Hz, the third mode is 2.2 Hz in transverse direction, fourth and fifth mode is 5.8 Hz and 7.0 Hz. For ground natural frequencies are in range 1.0 Hz to 1.3 Hz for North-South direction and 1.0 Hz to 1.6 Hz for East-West direction. Finally the results are compared with several empirical formulas for simple

  1. Virtual Shaker Testing: Simulation Technology Improves Vibration Test Performance

    Science.gov (United States)

    Ricci, Stefano; Peeters, Bart; Fetter, Rebecca; Boland, Doug; Debille, Jan

    2008-01-01

    In the field of vibration testing, the interaction between the structure being tested and the instrumentation hardware used to perform the test is a critical issue. This is particularly true when testing massive structures (e.g. satellites), because due to physical design and manufacturing limits, the dynamics of the testing facility often couples with the test specimen one in the frequency range of interest. A further issue in this field is the standard use of a closed loop real-time vibration control scheme, which could potentially shift poles and change damping of the aforementioned coupled system. Virtual shaker testing is a novel approach to deal with these issues. It means performing a simulation which closely represents the real vibration test on the specific facility by taking into account all parameters which might impact the dynamic behavior of the specimen. In this paper, such a virtual shaker testing approach is developed. It consists of the following components: (1) Either a physical-based or an equation-based coupled electro-mechanical lumped parameter shaker model is created. The model parameters are obtained from manufacturer's specifications or by carrying out some dedicated experiments; (2) Existing real-time vibration control algorithm are ported to the virtual simulation environment; and (3) A structural model of the test object is created and after defining proper interface conditions structural modes are computed by means of the well-established Craig-Bampton CMS technique. At this stage, a virtual shaker test has been run, by coupling the three described models (shaker, control loop, structure) in a co-simulation routine. Numerical results have eventually been correlated with experimental ones in order to assess the robustness of the proposed methodology.

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

    Science.gov (United States)

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

    2016-12-01

    In this paper, we present design and test of a broadband electrostatic energy harvester with a dual resonant structure, which consists of two cantilever-mass subsystems each with a mass attached at the free edge of a cantilever. Comparing to traditional devices with single resonant frequency, the proposed device with dual resonant structure can resonate at two frequencies. Furthermore, when one of the cantilever-masses is oscillating at resonance, the vibration amplitude is large enough to make it collide with the other mass, which provides strong mechanical coupling between the two subsystems. Therefore, this device can harvest a decent power output from vibration sources at a broad frequency range. During the measurement, continuous power output up to 6.2-9.8 μW can be achieved under external vibration amplitude of 9.3 m/s2 at a frequency range from 36.3 Hz to 48.3 Hz, which means the bandwidth of the device is about 30% of the central frequency. The broad bandwidth of the device provides a promising application for energy harvesting from the scenarios with random vibration sources. The experimental results indicate that with the dual resonant structure, the vibration-to-electricity energy conversion efficiency can be improved by 97% when an external random vibration with a low frequency filter is applied.

  3. Peri-prosthetic fracture vibration testing

    Energy Technology Data Exchange (ETDEWEB)

    Cruce, Jesse R [Los Alamos National Laboratory; Erwin, Jenny R [Los Alamos National Laboratory; Remick, Kevin R [Los Alamos National Laboratory; Cornwell, Phillip J [Los Alamos National Laboratory; Menegini, R. Michael [INDIANA UNIV.; Racanelli, Joe [STRYKER ORTHOPARDICS

    2010-11-08

    The purpose of this study was to establish a test setup and vibration analysis method to predict femoral stem seating and prevent bone fracture using accelerometer and force response data from an instrumented stem and impactor. This study builds upon earlier studies to identify a means to supplement a surgeon's tactile and auditory senses by using damage identification techniques normally used for civil and mechanical structures. Testing was conducted using foam cortical shell sawbones prepared for stems of different geometries. Each stem was instrumented with an accelerometer. Two impactor designs were compared: a monolithic impactor and a two-piece impactor, each with an integrated load cell and accelerometer. Acceleration and force measurements were taken in the direction of impaction. Comparisons between different methods of applying an impacting force were made, including a drop tower and a surgical hammer. The effect of varying compliance on the data was also investigated. The ultimate goal of this study was to assist in the design of an integrated portable data acquisition system capable of being used in future cadaveric testing. This paper will discuss the experimental setup and the subsequent results of the comparisons made between impactors, prosthetic geometries, compliances, and impact methods. The results of this study can be used for both future replicate testing as well as in a cadaveric environment.

  4. Random matrix theory approach to vibrations near the jamming transition

    Science.gov (United States)

    Beltukov, Y. M.

    2015-03-01

    It has been shown that the dynamical matrix M describing harmonic oscillations in granular media can be represented in the form M = AA T, where the rows of the matrix A correspond to the degrees of freedom of individual granules and its columns correspond to elastic contacts between granules. Such a representation of the dynamical matrix makes it possible to estimate the density of vibrational states with the use of the random matrix theory. The found density of vibrational states is approximately constant in a wide frequency range ω- < ω < ω+, which is determined by the ratio of the number of degrees of freedom to the total number of contacts in the system, which is in good agreement with the results of the numerical experiments.

  5. Damping Estimation Using Free Decays and Ambient Vibration Tests

    DEFF Research Database (Denmark)

    Magalhães, Filipe; Brincker, Rune; Cunha, Álvaro

    2007-01-01

    The accurate identification of modal damping ratios of Civil Engineering structures is a subject of major importance, as the amplitude of structural vibrations in resonance is inversely proportional to these coefficients. Their experimental identification can be performed either from ambient...... vibration or from free vibration tests. In the last case, the structural response after application of an impulse or after the application of harmonic loads can be used. Ambient vibration tests have the strong advantage of being more practical and economical. However, recent applications of both approaches...

  6. Application of a computerized vibroacoustic data bank for random vibration criteria development

    Science.gov (United States)

    Ferebee, R. C.

    1982-01-01

    A computerized data bank system was developed for utilization of large amounts of vibration and acoustic data to formulate component random vibration design and test criteria. This system consists of a computer, graphics tablets, and a dry silver hard copier which are all desk top type hardware and occupy minimal space. Currently, the data bank contains data from the Saturn 5 and Titan 3 flight and static test programs. The vibration and acoustic data are stored in the form of power spectral density and one third octave band plots over the frequency range from 20 to 2000 Hz. The data were stored by digitizing each spectral plot by tracing with the graphics tablet. The digitized data were statistically analyzed, and the resulting 97.5 percent confidence levels were stored on tape along with the appropriate structural parameters. Standard extrapolation procedures were programmed for prediction of component random vibration test criteria for new launch vehicle and payload configurations. A user's manual is included to guide potential users through the programs.

  7. KNOTS AND RANDOM WALKS IN VIBRATED GRANULAR CHAINS

    Energy Technology Data Exchange (ETDEWEB)

    E. BEN-NAIM; ET AL

    2000-08-01

    The authors study experimentally statistical properties of the opening times of knots in vertically vibrated granular chains. Our measurements are in good qualitative and quantitative agreement with a theoretical model involving three random walks interacting via hard core exclusion in one spatial dimension. In particular, the knot survival probability follows a universal scaling function which is independent of the chain length, with a corresponding diffusive characteristic time scale. Both the large-exit-time and the small-exit-time tails of the distribution are suppressed exponentially, and the corresponding decay coefficients are in excellent agreement with the theoretical values.

  8. Random Vibration of Space Shuttle Weather Protection Systems

    Directory of Open Access Journals (Sweden)

    Isaac Elishakoff

    1995-01-01

    Full Text Available The article deals with random vibrations of the space shuttle weather protection systems. The excitation model represents a fit to the measured experimental data. The cross-spectral density is given as a convex combination of three exponential functions. It is shown that for the type of loading considered, the Bernoulli-Euler theory cannot be used as a simplified approach, and the structure will be more properly modeled as a Timoshenko beam. Use of the simple Bernoulli-Euler theory may result in an error of about 50% in determining the mean-square value of the bending moment in the weather protection system.

  9. Test Operations Procedure (TOP) 01-2-603 Rotorcraft Laboratory Vibration Test Schedules

    Science.gov (United States)

    2017-06-12

    Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Test Operations Procedure (TOP) 01-2-603 Rotorcraft Laboratory Vibration Test Schedules...This TOP provides Laboratory Vibration Test Schedules (LVTS) for selected rotary wing aircraft. The LVTS presented in this TOP were developed from... vibration environment of a given rotary wing platform in a laboratory setting. 15. SUBJECT TERMS Laboratory Vibration Test Schedule (LVTS

  10. Power Delivered to Mechanical Systems by Random Vibrations

    Directory of Open Access Journals (Sweden)

    Timothy S. Edwards

    2009-01-01

    Full Text Available This paper develops deformational response power descriptions of multiple degree-of-freedom systems due to stationary random vibration excitation. Two new concepts are developed. The deformational response power density (DRPD can be computed when a structure's natural frequencies and modal masses are available. The DRPD shows the spectral content of the deformational power delivered to a specific structure by the stationary, random excitation. This function can be found through a weighted windowing of the power spectrum of the input acceleration excitation. Deformational response input power spectra (DRIPS, similar to the input energy spectrum and shock response spectrum, give the power delivered to single-degree-of-freedom systems as a function of natural frequency. It is shown that the DRIPS is simply a smoothed version of the power spectrum of the input acceleration excitation. The DRIPS gives rise to a useful power-based data smoothing operation.

  11. Vibration-based testing of bolted joints

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel; Sah, Si Mohamed; Fidlin, Alexander

    2017-01-01

    In recent pilot studies we have started investigating how to possibly use measured flexural (i.e. transverse/bending) vibrations, induced by bolt-tapping, to estimate bolt tightness. Some of the vibration features we investigated showed strong correlation with bolt tightness. For example, the low...... to bolt tension, but also to slenderness ratio. Thus, if only the natural frequency feature were to be used for estimating bolt tension, accuracy will drop off for the short and thick bolts that are often used in critical joints....

  12. Whole body vibration for older persons: an open randomized, multicentre, parallel, clinical trial

    Directory of Open Access Journals (Sweden)

    Sitjà-Rabert Mercè

    2011-12-01

    Full Text Available Abstract Background Institutionalized older persons have a poor functional capacity. Including physical exercise in their routine activities decreases their frailty and improves their quality of life. Whole-body vibration (WBV training is a type of exercise that seems beneficial in frail older persons to improve their functional mobility, but the evidence is inconclusive. This trial will compare the results of exercise with WBV and exercise without WBV in improving body balance, muscle performance and fall prevention in institutionalized older persons. Methods/Design An open, multicentre and parallel randomized clinical trial with blinded assessment. 160 nursing home residents aged over 65 years and of both sexes will be identified to participate in the study. Participants will be centrally randomised and allocated to interventions (vibration or exercise group by telephone. The vibration group will perform static/dynamic exercises (balance and resistance training on a vibratory platform (Frequency: 30-35 Hz; Amplitude: 2-4 mm over a six-week training period (3 sessions/week. The exercise group will perform the same exercise protocol but without a vibration stimuli platform. The primary outcome measure is the static/dynamic body balance. Secondary outcomes are muscle strength and, number of new falls. Follow-up measurements will be collected at 6 weeks and at 6 months after randomization. Efficacy will be analysed on an intention-to-treat (ITT basis and 'per protocol'. The effects of the intervention will be evaluated using the "t" test, Mann-Witney test, or Chi-square test, depending on the type of outcome. The final analysis will be performed 6 weeks and 6 months after randomization. Discussion This study will help to clarify whether WBV training improves body balance, gait mobility and muscle strength in frail older persons living in nursing homes. As far as we know, this will be the first study to evaluate the efficacy of WBV for the

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

    Science.gov (United States)

    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.

  14. Non-stationary random vibration analysis of structures under multiple correlated normal random excitations

    Science.gov (United States)

    Li, Yanbin; Mulani, Sameer B.; Kapania, Rakesh K.; Fei, Qingguo; Wu, Shaoqing

    2017-07-01

    An algorithm that integrates Karhunen-Loeve expansion (KLE) and the finite element method (FEM) is proposed to perform non-stationary random vibration analysis of structures under excitations, represented by multiple random processes that are correlated in both time and spatial domains. In KLE, the auto-covariance functions of random excitations are discretized using orthogonal basis functions. The KLE for multiple correlated random excitations relies on expansions in terms of correlated sets of random variables reflecting the cross-covariance of the random processes. During the response calculations, the eigenfunctions of KLE used to represent excitations are applied as forcing functions to the structure. The proposed algorithm is applied to a 2DOF system, a 2D cantilever beam and a 3D aircraft wing under both stationary and non-stationary correlated random excitations. Two methods are adopted to obtain the structural responses: a) the modal method and b) the direct method. Both the methods provide the statistics of the dynamic response with sufficient accuracy. The structural responses under the same type of correlated random excitations are bounded by the response obtained by perfectly correlated and uncorrelated random excitations. The structural response increases with a decrease in the correlation length and with an increase in the correlation magnitude. The proposed methodology can be applied for the analysis of any complex structure under any type of random excitation.

  15. Development of seismic technology and reliability based on vibration tests

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Youichi [Nuclear Power Engineering Corp., Tokyo (Japan)

    1997-03-01

    This paper deals with some of the vibration tests and investigations on the seismic safety of nuclear power plants (NPPs) in Japan. To ensure the reliability of the seismic safety of nuclear power plants, nuclear power plants in Japan have been designed according to the Technical Guidelines for Aseismic Design of Nuclear Power Plants. This guideline has been developed based on technical date base and findings which were obtained from many vibration tests and investigations. Besides the tests for the guideline, proving tests on seismic reliability of operating nuclear power plants equipment and systems have been carried out. In this paper some vibration tests and their evaluation results are presented. They have crucially contributed to develop the guideline. (J.P.N.)

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

    Science.gov (United States)

    Ferebee, R. C.

    1982-01-01

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

  17. 49 CFR Appendix C to Part 173 - Procedure for Base-level Vibration Testing

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Procedure for Base-level Vibration Testing C... Base-level Vibration Testing Base-level vibration testing shall be conducted as follows: 1. Three... platform. 4. Immediately following the period of vibration, each package shall be removed from the platform...

  18. Vibration Testing of NASA's Time Machine Near-Infrared Spectrograph

    Science.gov (United States)

    Jentsch, M.; Knecht, M.; Jollet, D.; Kommer, A.

    2014-06-01

    "NASA, ESA, and the Canadian Space Agency (CSA) are collaborating to develop JWST, a successor to the Hubble Space Telescope and enable observation and measurement of infrared wavelengths. JWST will be able to study every phase in the evolution of the Universe in great detail - from the first stars and galaxies to form after the Big Bang to the formation of planetary systems in our own Milky Way galaxy today. This will be made possible by JWST's huge primary mirror (which, with 18 hexagonal segments spanning a total of six and a half metres in diameter, will be the largest telescope in space) and its suite of four highly- sensitive scientific instruments, one of which is NIRSpec, able to detect the faintest radiation from the most distant galaxies.Mostly made from silicon carbide (SiC100), NIRSpec weighs only 200 kilograms and will operate at temperatures of -233°C as JWST orbits 1.5 million kilometres away from Earth. Once in space, the telescope and its instruments will remain in operation for up to 10 years." [4]The NIRSpec Optical Assembly consists of a ceramic optical bench supported by a set of hybrid kinematic mounts, several high performance optical subassemblies (e.g. the three mirror anastigmats (TMAs) also made of silicon carbide), mechanisms and a micro shutter assembly (MSA) which allows a detailed selection of at least 100 objects simultaneously at various spectral resolutions.Besides many other environmental testing the structural mechanics test campaign was divided into two parts. The qualification has been performed with the ETU (engineering test unit) consisting of the optical bench including the mounts and all ceramic parts in flight like configuration. A part of the subassemblies has been substituted by flight representative design models. Sine and random vibration qualification runs in three spatial axes have been performed to fulfil the requirements derived for the spacecraft configuration to cover Ariane 5 launch loads and the JWST program

  19. On Modal Parameter Estimates from Ambient Vibration Tests

    DEFF Research Database (Denmark)

    Agneni, A.; Brincker, Rune; Coppotelli, B.

    2004-01-01

    Modal parameter estimates from ambient vibration testing are turning into the preferred technique when one is interested in systems under actual loadings and operational conditions. Moreover, with this approach, expensive devices to excite the structure are not needed, since it can be adequately...

  20. An equipment test for grading lumber by transverse vibration technique

    Directory of Open Access Journals (Sweden)

    Marcelo Rodrigo Carreira

    2008-08-01

    Full Text Available Due to the great variability of its mechanical properties, the rational use of lumber for structural purposes is directly conditioned to its grading. There are several techniques available for grading structural lumber. The most relevant one is the transverse vibration technique which obtained reliable results in non-destructive evaluation of lumber. The purpose of this work is to present the bases for the mechanical grading of lumber and the results of the calibration test of the frst transverse vibration equipment developed in Brazil. In this research 30 beams of cupiúba (Goupia glabra with nominal dimensions of 5 cm X 10 cm X 300 cm, were used. The tests were accomplished at the Wood and Timber Structures Laboratory (LaMEM of the University of São Paulo (USP. The results showed a strong correlation between the elasticity modulus measured by the static bending test and the one obtained with the transverse vibration equipment, showing the high reliability of the vibration method for the grading of structural lumber. A determination coeffcient (R² of 0.896 was obtained with the Brazilian equipment, showing that it can be used in the grading of lumber.

  1. A Randomized Controlled Trial of Whole Body Vibration Exposure on Markers of Bone Turnover in Postmenopausal Women

    Science.gov (United States)

    Turner, Sarah; Torode, Margaret; Climstein, Mike; Naughton, Geraldine; Greene, David; Baker, Michael K.; Fiatarone Singh, Maria A.

    2011-01-01

    Purpose. To examine the effects of two doses of low-frequency (12 Hz), low-magnitude (0.3 g), whole body vibration on markers of bone formation and resorption in postmenopausal women. Methods. Women were recruited and randomized into a sham vibration control group, one time per week vibration group (1×/week), or three times per week vibration group (3×/week). Vibration exposure consisted of 20 minutes of intermittent vibration for the 1×/week and 3×/week groups, and sham vibration (vibration group but not in the 1×/wk vibration group compared with sham control (P vibration 3×/week for eight weeks in postmenopausal women results in a significant reduction in NTx/Cr, a marker of bone resorption, when compared with sham vibration exposure. PMID:21772975

  2. Modal confidence factor in vibration testing

    Science.gov (United States)

    Ibrahim, S. R.

    1978-01-01

    The modal confidence factor (MCF) is a number calculated for every identified mode for a structure under test. The MCF varies from 0.00 for a distorted nonlinear, or noise mode to 100.0 for a pure structural mode. The theory of the MCF is based on the correlation that exists between the modal deflection at a certain station and the modal deflection at the same station delayed in time. The theory and application of the MCF are illustrated by two experiments. The first experiment deals with simulated responses from a two-degree-of-freedom system with 20%, 40%, and 100% noise added. The second experiment was run on a generalized payload model. The free decay response from the payload model contained 22% noise.

  3. Effect of Vibration on Pain Response to Heel Lance: A Pilot Randomized Control Trial.

    Science.gov (United States)

    McGinnis, Kate; Murray, Eileen; Cherven, Brooke; McCracken, Courtney; Travers, Curtis

    2016-12-01

    Applied mechanical vibration in pediatric and adult populations has been shown to be an effective analgesic for acute and chronic pain, including needle pain. Studies among the neonatal population are lacking. According to the Gate Control Theory, it is expected that applied mechanical vibration will have a summative effect with standard nonpharmacologic pain control strategies, reducing behavioral and physiologic pain responses to heel lancing. To determine the safety and efficacy of mechanical vibration for relief of heel lance pain among neonates. In this parallel design randomized controlled trial, eligible enrolled term or term-corrected neonates (n = 56) in a level IV neonatal intensive care unit were randomized to receive either sucrose and swaddling or sucrose, swaddling, and vibration for heel lance analgesia. Vibration was applied using a handheld battery-powered vibrator (Norco MiniVibrator, Hz = 92) to the lateral aspect of the lower leg along the sural dermatome throughout the heel lance procedure. Neonatal Pain, Agitation, and Sedation Scale (N-PASS) scores, heart rate, and oxygen saturations were collected at defined intervals surrounding heel lancing. Infants in the vibration group (n = 30) had significantly lower N-PASS scores and more stable heart rates during heel stick (P = .006, P = .037) and 2 minutes after heel lance (P = .002, P = .016) than those in the nonvibration group. There were no adverse behavioral or physiologic responses to applied vibration in the sample. Applied mechanical vibration is a safe and effective method for managing heel lance pain. This pilot study suggests that mechanical vibration warrants further exploration as a nonpharmacologic pain management tool among the neonatal population.

  4. 30 CFR 27.39 - Tests to determine resistance to vibration.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Tests to determine resistance to vibration. 27... determine resistance to vibration. (a) Laboratory tests for reliability and durability. Components... two separate vibration tests, each of one-hour duration. The first test shall be conducted at a...

  5. NASA-DoD Lead-Free Electronics Project: Vibration Test

    Science.gov (United States)

    Woodrow, Thomas A.

    2010-01-01

    Vibration testing was conducted by Boeing Research and Technology (Seattle) for the NASA-DoD Lead-Free Electronics Solder Project. This project is a follow-on to the Joint Council on Aging Aircraft/Joint Group on Pollution Prevention (JCAA/JG-PP) Lead-Free Solder Project which was the first group to test the reliability of lead-free solder joints against the requirements of the aerospace/miLItary community. Twenty seven test vehicles were subjected to the vibration test conditions (in two batches). The random vibration Power Spectral Density (PSD) input was increased during the test every 60 minutes in an effort to fail as many components as possible within the time allotted for the test. The solder joints on the components were electrically monitored using event detectors and any solder joint failures were recorded on a Labview-based data collection system. The number of test minutes required to fail a given component attached with SnPb solder was then compared to the number of test minutes required to fail the same component attached with lead-free solder. A complete modal analysis was conducted on one test vehicle using a laser vibrometer system which measured velocities, accelerations, and displacements at one . hundred points. The laser vibrometer data was used to determine the frequencies of the major modes of the test vehicle and the shapes of the modes. In addition, laser vibrometer data collected during the vibration test was used to calculate the strains generated by the first mode (using custom software). After completion of the testing, all of the test vehicles were visually inspected and cross sections were made. Broken component leads and other unwanted failure modes were documented.

  6. Online vibration-based crack detection during fatigue testing

    Energy Technology Data Exchange (ETDEWEB)

    Peeters, B.; Vecchio, A.; Auweraer, H. van der [LMS International, Heverlee (Belgium); Mevel, L. [INRIA, Rennes (France); Vanlanduit, S.; Guillaume, P. [Dept. of Mechanical Engineering, VUB, Brussels (Belgium); Goursat, M. [Rocquencourt, INRIA, Le Chesnay (France)

    2003-07-01

    When performing fatigue tests, it is essential to monitor the degradation of the structure with an increasing number of fatigue cycles. In this article, a vibration-based damage detection method will be proposed. Such a method has the advantage that it operates online with the fatigue test. Especially for structures with very high fatigue strength, it is important that the test does not have to be interrupted. The damage detection method that will be used is based on a residual generated from a stochastic subspace identification method. The basic idea is that a model for the undamaged structure is identified and that, afterwards, vibration measurements from a possibly damaged structure are confronted with this model. A statistical local approach hypothesis testing is used to assess the deviation of the new data from the nominal model. After introducing the damage detection method, its performance will be illustrated on data from a fatigue experiment. The method will be compared to other linear and non-linear vibration-based damage detection methods. (orig.)

  7. Stochastic resonance whole-body vibration improves postural control in health care professionals: a worksite randomized controlled trial.

    Science.gov (United States)

    Elfering, Achim; Schade, Volker; Stoecklin, Lukas; Baur, Simone; Burger, Christian; Radlinger, Lorenz

    2014-05-01

    Slip, trip, and fall injuries are frequent among health care workers. Stochastic resonance whole-body vibration training was tested to improve postural control. Participants included 124 employees of a Swiss university hospital. The randomized controlled trial included an experimental group given 8 weeks of training and a control group with no intervention. In both groups, postural control was assessed as mediolateral sway on a force plate before and after the 8-week trial. Mediolateral sway was significantly decreased by stochastic resonance whole-body vibration training in the experimental group but not in the control group that received no training (p resonance whole-body vibration training is an option in the primary prevention of balance-related injury at work. Copyright 2014, SLACK Incorporated.

  8. Adaptive and robust active vibration control methodology and tests

    CERN Document Server

    Landau, Ioan Doré; Castellanos-Silva, Abraham; Constantinescu, Aurelian

    2017-01-01

    This book approaches the design of active vibration control systems from the perspective of today’s ideas of computer control. It formulates the various design problems encountered in the active management of vibration as control problems and searches for the most appropriate tools to solve them. The experimental validation of the solutions proposed on relevant tests benches is also addressed. To promote the widespread acceptance of these techniques, the presentation eliminates unnecessary theoretical developments (which can be found elsewhere) and focuses on algorithms and their use. The solutions proposed cannot be fully understood and creatively exploited without a clear understanding of the basic concepts and methods, so these are considered in depth. The focus is on enhancing motivations, algorithm presentation and experimental evaluation. MATLAB®routines, Simulink® diagrams and bench-test data are available for download and encourage easy assimilation of the experimental and exemplary material. Thre...

  9. On the Shaker Simulation of Wind-Induced Non-Gaussian Random Vibration

    Directory of Open Access Journals (Sweden)

    Fei Xu

    2016-01-01

    Full Text Available Gaussian signal is produced by ordinary random vibration controllers to test the products in the laboratory, while the field data is usually non-Gaussian. Two methodologies are presented in this paper for shaker simulation of wind-induced non-Gaussian vibration. The first methodology synthesizes the non-Gaussian signal offline and replicates it on the shaker in the Time Waveform Replication (TWR mode. A new synthesis method is used to model the non-Gaussian signal as a Gaussian signal multiplied by an amplitude modulation function (AMF. A case study is presented to show that the synthesized non-Gaussian signal has the same power spectral density (PSD, probability density function (PDF, and loading cycle distribution (LCD as the field data. The second methodology derives a damage equivalent Gaussian signal from the non-Gaussian signal based on the fatigue damage spectrum (FDS and the extreme response spectrum (ERS and reproduces it on the shaker in the closed-loop frequency domain control mode. The PSD level and the duration time of the derived Gaussian signal can be manipulated for accelerated testing purpose. A case study is presented to show that the derived PSD matches the damage potential of the non-Gaussian environment for both fatigue and peak response.

  10. Acoustically Induced Vibration of Structures: Reverberant Vs. Direct Acoustic Testing

    Science.gov (United States)

    Kolaini, Ali R.; O'Connell, Michael R.; Tsoi, Wan B.

    2009-01-01

    Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose unanticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in

  11. Testing of Tools for Measurement Vibration in Car

    Directory of Open Access Journals (Sweden)

    Martin JURÁNEK

    2009-06-01

    Full Text Available This work is specialized on testing of several sensors for measurement vibration, that be applicable for measurement on vehicles also behind running. These sensors are connected to PC and universal mobile measuring system cRIO (National Instruments with analog I/O module for measurement vibration, that is described in diploma work: [JURÁNEK 2008]. This system has upped mechanical and heat imunity, small proportions and is therefore acceptable also measurement behind ride vehicles. It compose from two head parts. First is measuring part, composite from instruments cRIO. First part is controlled and monitored by PDA there is connected of wireless (second part hereof system. To system cRIO is possible connect sensors by four BNC connector or after small software change is possible add sensor to other analog modul cRIO. Here will be test several different types of accelerometers (USB sensor company Phidgets, MEMS sensor company Freescale, piezoresistiv and Delta Tron accelerometers company Brüel&Kjær. These sensors is attach to stiff board, board is attach to vibrator and excite by proper signal. Testing will realized with reference to using for measurement in cars. Results will be compared with professional signal analyser LabShop pulse from company Brüel&Kjær.

  12. Random Vibration Analysis of the Tip-tilt System in the GMT Fast Steering Secondary Mirror

    Science.gov (United States)

    Lee, Kyoung-Don; Kim, Young-Soo; Kim, Ho-Sang; Lee, Chan-Hee; Lee, Won Gi

    2017-09-01

    A random vibration analysis was accomplished on the tip-tilt system of the fast steering secondary mirror (FSM) for the Giant Magellan Telescope (GMT). As the FSM was to be mounted on the top end of the secondary truss and disturbed by the winds, dynamic effects of the FSM disturbances on the tip-tilt correction performance was studied. The coupled dynamic responses of the FSM segments were evaluated with a suggested tip-tilt correction modeling. Dynamic equations for the tip-tilt system were derived from the force and moment equilibrium on the segment mirror and the geometric compatibility conditions with four design parameters. Statically stationary responses for the tip-tilt actuations to correct the wind-induced disturbances were studied with two design parameters based on the spectral density function of the star image errors in the frequency domain. Frequency response functions and root mean square values of the dynamic responses and the residual star image errors were numerically calculated for the off-axis and on-axis segments of the FSM. A prototype of on-axis segment of the FSM was developed for tip-tilt actuation tests to confirm the ratio of tip-tilt force to tip-tilt angle calculated from the suggested dynamic equations of the tip-tilt system. Tip-tilt actuation tests were executed at 4, 8 and 12 Hz by measuring displacements of piezoelectric actuators and reaction forces acting on the axial supports. The derived ratios of rms tip-tilt force to rms tip-tilt angle from tests showed a good correlation with the numerical results. The suggested process of random vibration analysis on the tip-tilt system to correct the wind-induced disturbances of the FSM segments would be useful to advance the FSM design and upgrade the capability to achieve the least residual star image errors by understanding the details of dynamics.

  13. Application of empirical mode decomposition method for characterization of random vibration signals

    Directory of Open Access Journals (Sweden)

    Setyamartana Parman

    2016-07-01

    Full Text Available Characterization of finite measured signals is a great of importance in dynamical modeling and system identification. This paper addresses an approach for characterization of measured random vibration signals where the approach rests on a method called empirical mode decomposition (EMD. The applicability of proposed approach is tested in one numerical and experimental data from a structural system, namely spar platform. The results are three main signal components, comprising: noise embedded in the measured signal as the first component, first intrinsic mode function (IMF called as the wave frequency response (WFR as the second component and second IMF called as the low frequency response (LFR as the third component while the residue is the trend. Band-pass filter (BPF method is taken as benchmark for the results obtained from EMD method.

  14. Efficacy of Whole-Body Vibration Board Training on Strength in Athletes After Anterior Cruciate Ligament Reconstruction: A Randomized Controlled Study.

    Science.gov (United States)

    Costantino, Cosimo; Bertuletti, Silvia; Romiti, Davide

    2017-06-22

    To evaluate whether an 8-week whole-body vibration training program may improve recovery of knee flexion/extension muscular strength in athletes after arthroscopic anterior cruciate ligament (ACL) reconstruction. Randomized controlled trial. Single outpatient rehabilitation center. Thirty-eight female volleyball/basketball players (aged between 20 and 30), randomized into 2 treatment groups. During a standardized six-month rehabilitation program, from week 13 to week 20 after surgery, the whole-body vibration group (n = 19) and the control group (n = 19) performed additional static knee flexor/extensor exercises on a vibration platform. For the whole-body vibration group, the vibration platform was set to 2.5 mm of amplitude and 26 Hz of frequency. The control group followed the same whole-body vibration board training with no vibrations. All patients were evaluated using an isokinetic strength test with a Biodex dynamometer at the beginning and at the end of the additional treatment protocol. The parameters tested were the peak torque and the maximum power of knee flexor and extensor muscles performing strength and endurance tests. No vibration-related side effects were observed. Improvements were noticed in both groups, but increase in knee muscle isokinetic strength values was statistically significant in the whole-body vibration group when compared with the control group (differences in extension: peak torque 11.316/10.263 N·m and maximum power 13.684/11.211 W; flexion: peak torque 9.632/11.105 N·m and maximum power 10.158/9.474 W; P < 0.001). When combined with a standardized rehabilitation program, whole-body vibration may increase muscular strength and be an effective additional treatment option in the rehabilitation of athletes after ACL arthroscopic reconstruction.

  15. 49 CFR 382.305 - Random testing.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Random testing. 382.305 Section 382.305... ALCOHOL USE AND TESTING Tests Required § 382.305 Random testing. (a) Every employer shall comply with the requirements of this section. Every driver shall submit to random alcohol and controlled substance testing as...

  16. Measurement of Dynamic Viscoelasticity of Full-Size Wood Composite Panels Using a Vibration Testing Method

    Science.gov (United States)

    Cheng Guan; Houjiang Zhang; John F. Hunt; Lujing Zhou; Dan Feng

    2016-01-01

    The dynamic viscoelasticity of full-size wood composite panels (WCPs) under the free-free vibrational state were determined by a vibration testing method. Vibration detection tests were performed on 194 pieces of three types of full-size WCPs (particleboard, medium density fiberboard, and plywood (PW)). The dynamic viscoelasticity from smaller specimens cut from the...

  17. Vibration and Acoustic Test Facility (VATF): User Test Planning Guide

    Science.gov (United States)

    Fantasia, Peter M.

    2011-01-01

    Test process, milestones and inputs are unknowns to first-time users of the VATF. The User Test Planning Guide aids in establishing expectations for both NASA and non-NASA facility customers. The potential audience for this guide includes both internal and commercial spaceflight hardware/software developers. It is intended to assist their test engineering personnel in test planning and execution. Material covered includes a roadmap of the test process, roles and responsibilities of facility and user, major milestones, facility capabilities, and inputs required by the facility. Samples of deliverables, test article interfaces, and inputs necessary to define test scope, cost, and schedule are included as an appendix to the guide.

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

    Directory of Open Access Journals (Sweden)

    Shanshan Li

    2016-01-01

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

  19. Integrated Vehicle Ground Vibration Testing of Manned Spacecraft: Historical Precedent

    Science.gov (United States)

    Lemke, Paul R.; Tuma, Margaret L.; Askins, Bruce R.

    2008-01-01

    For the first time in nearly 30 years, NASA is developing a new manned space flight launch system. The Ares I will carry crew and cargo to not only the International Space Station, but onward for the future exploration of the Moon and Mars. The Ares I control system and structural designs use complex computer models for their development. An Integrated Vehicle Ground Vibration Test (IVGVT) will validate the efficacy of these computer models. The IVGVT will reduce the technical risk of unexpected conditions that could place the vehicle or crew in jeopardy. The Ares Project Office's Flight and Integrated Test Office commissioned a study to determine how historical programs, such as Saturn and Space Shuttle, validated the structural dynamics of an integrated flight vehicle. The study methodology was to examine the historical record and seek out members of the engineering community who recall the development of historic manned launch vehicles. These records and interviews provided insight into the best practices and lessons learned from these historic development programs. The information that was gathered allowed the creation of timelines of the historic development programs. The timelines trace the programs from the development of test articles through test preparation, test operations, and test data reduction efforts. These timelines also demonstrate how the historical tests fit within their overall vehicle development programs. Finally, the study was able to quantify approximate staffing levels during historic development programs. Using this study, the Flight and Integrated Test Office was able to evaluate the Ares I Integrated Vehicle Ground Vibration Test schedule and workforce budgets in light of the historical precedents to determine if the test had schedule or cost risks associated with it.

  20. 49 CFR 655.45 - Random testing.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 7 2010-10-01 2010-10-01 false Random testing. 655.45 Section 655.45... of Testing § 655.45 Random testing. (a) Except as provided in paragraphs (b) through (d) of this section, the minimum annual percentage rate for random drug testing shall be 50 percent of covered...

  1. Modal vibration testing of the DVA-1 radio telescope

    Science.gov (United States)

    Byrnes, Peter W. G.; Lacy, Gordon

    2016-07-01

    The Dish Verification Antenna 1 (DVA-1) is a 15m aperture offset Gregorian radio telescope featuring a rim-supported single piece molded composite primary reflector on an altitude-azimuth pedestal mount. Vibration measurements of the DVA-1 telescope were conducted over three days in October 2014 by NSI Herzberg engineers. The purpose of these tests was to measure the first several natural frequencies of the DVA-1 telescope. This paper describes the experimental approach, in particular the step-release method, and summarizes some interesting results, including unexpectedly high damping of the first mode over a narrow range of zenith angles.

  2. A Novel Vibration Mode Testing Method for Cylindrical Resonators Based on Microphones

    Directory of Open Access Journals (Sweden)

    Yongmeng Zhang

    2015-01-01

    Full Text Available Non-contact testing is an important method for the study of the vibrating characteristic of cylindrical resonators. For the vibratory cylinder gyroscope excited by piezo-electric electrodes, mode testing of the cylindrical resonator is difficult. In this paper, a novel vibration testing method for cylindrical resonators is proposed. This method uses a MEMS microphone, which has the characteristics of small size and accurate directivity, to measure the vibration of the cylindrical resonator. A testing system was established, then the system was used to measure the vibration mode of the resonator. The experimental results show that the orientation resolution of the node of the vibration mode is better than 0.1°. This method also has the advantages of low cost and easy operation. It can be used in vibration testing and provide accurate results, which is important for the study of the vibration mode and thermal stability of vibratory cylindrical gyroscopes.

  3. Used fuel rail shock and vibration testing options analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Steven B. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Best, Ralph E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Klymyshyn, Nicholas A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jensen, Philip J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Maheras, Steven J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-09-25

    The objective of the rail shock and vibration tests is to complete the framework needed to quantify loads of fuel assembly components that are necessary to guide materials research and establish a technical basis for review organizations such as the U.S. Nuclear Regulatory Commission (NRC). A significant body of experimental and numerical modeling data exists to quantify loads and failure limits applicable to normal conditions of transport (NCT) rail transport, but the data are based on assumptions that can only be verified through experimental testing. The test options presented in this report represent possible paths for acquiring the data that are needed to confirm the assumptions of previous work, validate modeling methods that will be needed for evaluating transported fuel on a case-by-case basis, and inform material test campaigns on the anticipated range of fuel loading. The ultimate goal of this testing is to close all of the existing knowledge gaps related to the loading of used fuel under NCT conditions and inform the experiments and analysis program on specific endpoints for their research. The options include tests that would use an actual railcar, surrogate assemblies, and real or simulated rail transportation casks. The railcar carrying the cradle, cask, and surrogate fuel assembly payload would be moved in a train operating over rail track modified or selected to impart shock and vibration forces that occur during normal rail transportation. Computer modeling would be used to help design surrogates that may be needed for a rail cask, a cask’s internal basket, and a transport cradle. The objective of the design of surrogate components would be to provide a test platform that effectively simulates responses to rail shock and vibration loads that would be exhibited by state-of-the-art rail cask, basket, and/or cradle structures. The computer models would also be used to help determine the placement of instrumentation (accelerometers and strain gauges

  4. Stochastic resonance whole body vibration reduces musculoskeletal pain: A randomized controlled trial.

    Science.gov (United States)

    Elfering, Achim; Thomann, Jan; Schade, Volker; Radlinger, Lorenz

    2011-12-18

    To examined the effects of stochastic resonance whole-body vibration training on musculoskeletal pain in young healthy individuals. Participants were 43 undergraduate students of a Swiss University. The study was designed as a randomized controlled trial (RCT) with randomized group allocation. The RCT consisted of two groups each given 12 training sessions during four weeks with either 5 Hz- Training frequency (training condition) or 1.5 Hz Training frequency (control condition). Outcome was current musculoskeletal pain assessed in the evening on each day during the four week training period. Multilevel regression analysis showed musculoskeletal pain was significantly decreased in the training condition whereas there was no change in the control condition (B = -0.023, SE = 0.010, P = 0.021). Decrease in current musculoskeletal pain over four weeks was linear. Stochastic resonance whole-body vibration reduced musculoskeletal pain in young healthy individuals. Stochastic resonance vibration and not any other exercise component within training caused pain reduction.

  5. Early vibration assisted physiotherapy in toddlers with cerebral palsy - a randomized controlled pilot trial

    NARCIS (Netherlands)

    Stark, C.; Herkenrath, P.; Hollmann, H.; Waltz, S.; Becker, I.; Hoebing, L.; Semler, O.; Hoyer-Kuhn, H.; Duran, I.; Hero, B.; Hadders-Algra, M.; Schoenau, E.

    OBJECTIVES: to investigate feasibility, safety and efficacy of home-based side-alternating whole body vibration (sWBV) to improve motor function in toddlers with cerebral palsy (CP). METHODS: Randomized controlled trial including 24 toddlers with CP (mean age 19 months (SD±3.1); 13 boys).

  6. DETERMINING THE RESPONSE IN CASE OF VIBRATIONS OF STRAIGHT BARS WITH RANDOM EXCITATIONS

    Directory of Open Access Journals (Sweden)

    Monica BALDEA

    2012-05-01

    Full Text Available By applying the finite element calculus to the study of bar vibrations, one obtains a system of linear diferential equations. One carries out the determination of the response to random stimulations by calculating the statistical terms as a function of the statistical terms of the stimulation

  7. Fatigue failure of materials under broad band random vibrations

    Science.gov (United States)

    Huang, T. C.; Lanz, R. W.

    1971-01-01

    The fatigue life of material under multifactor influence of broad band random excitations has been investigated. Parameters which affect the fatigue life are postulated to be peak stress, variance of stress and the natural frequency of the system. Experimental data were processed by the hybrid computer. Based on the experimental results and regression analysis a best predicting model has been found. All values of the experimental fatigue lives are within the 95% confidence intervals of the predicting equation.

  8. High Frequency Vibration Based Fatigue Testing of Developmental Alloys

    Science.gov (United States)

    Holycross, Casey M.; Srinivasan, Raghavan; George, Tommy J.; Tamirisakandala, Seshacharyulu; Russ, Stephan M.

    Many fatigue test methods have been previously developed to rapidly evaluate fatigue behavior. This increased test speed can come at some expense, since these methods may require non-standard specimen geometry or increased facility and equipment capability. One such method, developed by George et al, involves a base-excited plate specimen driven into a high frequency bending resonant mode. This resonant mode is of sufficient frequency (typically 1200 to 1700 Hertz) to accumulate 107 cycles in a few hours. One of the main limitations of this test method is that fatigue cracking is almost certainly guaranteed to be surface initiated at regions of high stress. This brings into question the validity of the fatigue test results, as compared to more traditional uniaxial, smooth-bar testing, since high stresses are subjecting only a small volume to fatigue damage. This limitation also brings into question the suitability of this method to screen developmental alloys, should their initiation life be governed by subsurface flaws. However, if applicable, the rapid generation of fatigue data using this method would facilitate faster design iterations, identifying more quickly, material and manufacturing process deficiencies. The developmental alloy used in this study was a powder metallurgy boron-modified Ti-6Al-4V, a new alloy currently being considered for gas turbine engine fan blades. Plate specimens were subjected to fully reversed bending fatigue. Results are compared with existing data from commercially available Ti-6Al-4V using both vibration based and more traditional fatigue test methods.

  9. Design of a Maglev Vibration Test Platform for the Research of Maglev Vehicle-girder Coupled Vibration Problem

    Directory of Open Access Journals (Sweden)

    Zhou Danfeng

    2017-01-01

    Full Text Available The maglev vehicle-girder coupled vibration problem has been encountered in many maglev test or commercial lines, which significantly degrade the performance of the maglev train. In previous research on the principle of the coupled vibration problem, it has been discovered that the fundamental model of the maglev girder can be simplified as a series of mass-spring resonators of different but related resonance frequencies, and that the stability of the vehicle-girder coupled system can be investigated by separately examining the stability of each mass-spring resonator – electromagnet coupled system. Based on this conclusion, a maglev test platform, which includes a single electromagnetic suspension control system, is built for experimental study of the coupled vibration problem. The guideway of the test platform is supported by a number of springs so as to change its flexibility. The mass of the guideway can also be changed by adjusting extra weights attached to it. By changing the flexibility and mass of the guideway, the rules of the maglev vehicle-girder coupled vibration problem are to be examined through experiments, and related theory on the vehicle-girder self-excited vibration proposed in previous research is also testified.

  10. QUASI-RANDOM TESTING OF COMPUTER SYSTEMS

    Directory of Open Access Journals (Sweden)

    S. V. Yarmolik

    2013-01-01

    Full Text Available Various modified random testing approaches have been proposed for computer system testing in the black box environment. Their effectiveness has been evaluated on the typical failure patterns by employing three measures, namely, P-measure, E-measure and F-measure. A quasi-random testing, being a modified version of the random testing, has been proposed and analyzed. The quasi-random Sobol sequences and modified Sobol sequences are used as the test patterns. Some new methods for Sobol sequence generation have been proposed and analyzed.

  11. Using the Saturn V and Titan III Vibroacoustic Databanks for Random Vibration Criteria Development

    Science.gov (United States)

    Ferbee, R C.

    2009-01-01

    This is an update to TN D-7159, "Development and Application of Vibroacoustic Structural Data Banks in Predicting Vibration Design and Test Criteria for Rocket Vehicle Structures", which was originally published in 1973. Errors in the original document have been corrected and additional data from the Titan III program have been included. Methods for using the vibroacoustic databanks for vibration test criteria development are shown, as well as all of the data with drawings and pictures of the measurement locations. An Excel spreadsheet with the data included is available from the author.

  12. Fuzzy norm method for evaluating random vibration of airborne platform from limited PSD data

    Directory of Open Access Journals (Sweden)

    Wang Zhongyu

    2014-12-01

    Full Text Available For random vibration of airborne platform, the accurate evaluation is a key indicator to ensure normal operation of airborne equipment in flight. However, only limited power spectral density (PSD data can be obtained at the stage of flight test. Thus, those conventional evaluation methods cannot be employed when the distribution characteristics and priori information are unknown. In this paper, the fuzzy norm method (FNM is proposed which combines the advantages of fuzzy theory and norm theory. The proposed method can deeply dig system information from limited data, which probability distribution is not taken into account. Firstly, the FNM is employed to evaluate variable interval and expanded uncertainty from limited PSD data, and the performance of FNM is demonstrated by confidence level, reliability and computing accuracy of expanded uncertainty. In addition, the optimal fuzzy parameters are discussed to meet the requirements of aviation standards and metrological practice. Finally, computer simulation is used to prove the adaptability of FNM. Compared with statistical methods, FNM has superiority for evaluating expanded uncertainty from limited data. The results show that the reliability of calculation and evaluation is superior to 95%.

  13. Structural Analysis of Pressurized Small Diameter Lines in a Random Vibration Environment

    Science.gov (United States)

    Davis, Mark; Ridnour, Andrew; Brethen, Mark

    2011-01-01

    The pressurization and propellant feed lines for the Ares 1 Upper Stage Reaction and Roll Control Systems (ReCS and RoCS) were required to be in a high g-load random vibration flight environment. The lines connected the system components and were filled with both liquid hydrazine and gaseous helium. They are considered small and varied between one fourth to one inch in diameter. The random vibration of the lines was considered to be base excitation through the mating components and mounting hardware. It was found that reducing the amount of support structure for the lines added flexibility to the system and improved the line stresses from random vibration, but caused higher stresses from the static g-loads. The locations and number of brackets were optimized by analyzing the mode shapes of the lines causing high stresses. The use of brackets that only constrain motion in the direction of concern further reduced the stresses in the lines. Finite element analysis was used to perform the analysis. The lines were pre-stressed by temperature and internal pressure with fluid and insulation included as non-structural mass. Base excitation was added to the model using Power Spectral Density (PSD) data for the expected flight loads. The random vibration and static g-load cases were combined to obtain the total stress in the lines. This approach advances the state of the art in line analysis by using FEA to predict the stresses in the lines and to optimize the entire system based on the expected flight environment. Adding flexibility to lines has been used in piping system for temperature loads, but in flight environments flexibility has been limited for the static stresses. Adding flexibility to the system in a flight environment by reducing brackets has the benefit of reducing stresses and weight

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

    DEFF Research Database (Denmark)

    Liang, Shanshan; Crovetto, Andrea; Peng, Zhuoteng

    2016-01-01

    and experiments with piezoelectric elements show that the energy harvesting device with the bi-resonant structure can generate higher power output than that of the sum of the two separate devices from random vibration sources at low frequency, and hence significantly improves the vibration-to- electricity...

  15. Prediction of Acoustically Induced Random Vibration Response of Satellite Equipments with Proposed Asymptotic Apparent Mass

    Science.gov (United States)

    Ando, Shigemasa; Shi, Qinzhong

    Acoustically induced random vibration of satellite equipment mounted on honeycomb panels is a critical design consideration in satellite equipment development. Prediction of this random vibration is performed in the early stage of satellite design to specify the design limit value of random vibration excitation for satellite equipment. Various prediction methods for response prediction using Statistical Energy Analysis (SEA) have been developed: (i) NASA Lewis method, (ii) point-mass impedance method, and (iii) area-coupling impedance method. However, the first method has limited accuracy for heavy and concentrated equipment, the second one often overestimates, and the third one requires a detailed parameter. A new method combining the asymptotic apparent mass of specific equipment with NASA Lewis method is proposed herein. This proposed method takes the elastic behavior of satellite equipment rather than a rigid mass. The acoustic excitation experiments for nine real satellites (404 equipments in all) were conducted to compare existing methods to the proposed method statistically. Results show that the proposed method provides the most accurate prediction in the important frequency range.

  16. The Influence of Acceleration on the Efficiency of Sand Compaction Tests Conducted on a Vibrating Table

    Science.gov (United States)

    Szajna, Waldemar St.

    2017-03-01

    The paper presents a standard vibrating table for fresh concrete testing adopted for determination of maximum dry density (ρdmax) of sand. Vibration is an efficient method for coarse soil compaction therefore vibrating tables are useful for ρdmax determination. Acceleration that the soil is subject to is one of the basic parameters of efficient compaction. A vibrating table with inertial excitation was supplemented by a frequency converter and subjected to dynamic tests. The results of measurements of dynamic parameters are included. The paper presents problems connected with this method and describes the relationship between efficiency of compaction and accelerations which the soil is subjected to.

  17. Stationary and nonstationary random vibrations of laminated composite plates via a higher order theory

    Science.gov (United States)

    Elishakoff, Isaac; Librescu, Liviu; Cederbaum, Gabriel

    1990-01-01

    Higher order shear deformation theory is utilized to study he weakly stationary and nonstationary random vibrations of cross-ply laminated plates. Normal mode method, in conjunction with the biorthogonality condition, for the nonsymmetric differential equations is applied. Detailed derivation is given for the governing equations, biorthogonality condition, the generalized mass and the generalized forces. Results are listed for a plate which is simply supported at all the edges, and subjected to a point load which is either timewise stationary or nonstationary random process.

  18. Random Vibration Analysis of Train Moving over Slab Track on Bridge under Track Irregularities and Earthquakes by Pseudoexcitation Method

    National Research Council Canada - National Science Library

    Zeng, Zhiping; Zhu, Kunteng; He, Xianfeng; Xu, Wentao; Chen, Lingkun; Lou, Ping

    2015-01-01

      This paper investigates the random vibration and the dynamic reliability of operation stability of train moving over slab track on bridge under track irregularities and earthquakes by the pseudoexcitation method (PEM...

  19. Analysis of subsystem randomness effects on the mid-frequency vibrations of built-up structures

    Science.gov (United States)

    Ji, Lin; Huang, Zhenyu

    2013-06-01

    The paper concerns the analysis of subsystem randomness effects on the mid-frequency vibration responses of built-up systems. The system model considered, in the first instance, is a long-wavelength finite element (FE) subsystem connected with a short-wavelength statistical energy analysis (SEA) subsystem via discrete couplings. The randomness effects of the SEA subsystem on both the displacement response of the FE subsystem and the energy response of the SEA subsystem are then investigated under the frame of the hybrid FE/SEA theory [P. Shorter, R. Langley, Vibro-acoustic analysis of complex systems, Journal of Sound and Vibration, 288 (2005) 669-700]. It is found that the subsystem randomness effects may be well indicated by a dimensionless parameter α, which is a function of the number of coupling points, the dynamic mismatch between the FE and SEA subsystems and the modal overlap factor of the SEA subsystem. The smaller the value of α is, the more insignificant the randomness effects are. As a result, a so-called "α-criterion" is derived which states that, if a built-up structure satisfies the condition of α≪1, the randomness effects of the SEA subsystem can be neglected. In this case, the SEA subsystem can be simply treated as an infinite (or semi-infinite as appropriate) structure regardless of its mode count being sufficiently high or not. Numerical examples are presented to illustrate the validity of the present theory.

  20. Integrated Vibration and Acceleration Testing to Reduce Payload Mass, Cost and Mission Risk Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop a capability to provide integrated acceleration, vibration, and shock testing using a state-of-the-art centrifuge, allowing for the test of...

  1. Random Vibration and Dynamic Analysis of a Planetary Gear Train in a Wind Turbine

    Directory of Open Access Journals (Sweden)

    Jianming Yang

    2016-01-01

    Full Text Available Premature failure of gearboxes is a big challenge facing the wind power industry. It highly depends on fully understanding the embedded dynamics to solve this problem. To this end, this paper investigates the random vibration and dynamics of planetary gear trains (PGTs in wind turbines under the excitation of wind turbulence. The turbulence is represented by the Von Karmon spectrum and implemented by passing white noise through a 2nd-order shaping filter. Then, extra equations are formed and added to the original governing equations of motion. With this augmented equation set, a recursive numerical algorithm based on stochastic Newmark scheme is applied to solve for the statistics of the responses starting from initial conditions. After simulation, the variances of the vibration responses and the dynamic meshing forces at gear meshes are obtained.

  2. The Shock and Vibration Bulletin. Part 4. Vibration Testing, Instrumentation, Loads and Environments, Tracked Vehicles

    Science.gov (United States)

    1978-09-01

    distribution. . % logic. Clock speeds were kept very low, extensive buf- fering and shielding were used, and capacitive filters were This idea was...As Lorisciousness of the • . o a load from a shorted to open circuit, and capacitive to concept grows. it is expected that the control systems...transducer, and an angular velocity vibrometer . for collecting a broad base of aircraft angular Their applications will be discussed in light vibration

  3. Topographic analysis of the skull vibration-induced nystagmus test with piezoelectric accelerometers and force sensors.

    Science.gov (United States)

    Dumas, Georges; Lion, Alexis; Perrin, Philippe; Ouedraogo, Evariste; Schmerber, Sébastien

    2016-03-23

    Vibration-induced nystagmus is elicited by skull or posterior cervical muscle stimulations in patients with vestibular diseases. Skull vibrations delivered by the skull vibration-induced nystagmus test are known to stimulate the inner ear structures directly. This study aimed to measure the vibration transfer at different cranium locations and posterior cervical regions to contribute toward stimulus topographic optimization (experiment 1) and to determine the force applied on the skull with a hand-held vibrator to study the test reproducibility and provide recommendations for good clinical practices (experiment 2). In experiment 1, a 100 Hz hand-held vibrator was applied on the skull (vertex, mastoids) and posterior cervical muscles in 11 healthy participants. Vibration transfer was measured by piezoelectric sensors. In experiment 2, the vibrator was applied 30 times by two experimenters with dominant and nondominant hands on a mannequin equipped to measure the force. Experiment 1 showed that after unilateral mastoid vibratory stimulation, the signal transfer was higher when recorded on the contralateral mastoid than on the vertex or posterior cervical muscles (Pvibration transfer was measured on vertex and posterior cervical muscles. Experiment 2 showed that the force applied to the mannequin varied according to the experimenters and the handedness, higher forces being observed with the most experienced experimenter and with the dominant hand (10.3 ± 1.0 and 7.8 ± 2.9 N, respectively). The variation ranged from 9.8 to 29.4% within the same experimenter. Bone transcranial vibration transfer is more efficient from one mastoid to the other mastoid than other anatomical sites. The mastoid is therefore the optimal site for skull vibration-induced nystagmus test in patients with unilateral vestibular lesions and enables a stronger stimulation of the healthy side. In clinical practice, the vibrator should be placed on the mastoid and should be held by the clinician

  4. Model for continuously scanning ultrasound vibrometer sensing displacements of randomly rough vibrating surfaces.

    Science.gov (United States)

    Ratilal, Purnima; Andrews, Mark; Donabed, Ninos; Galinde, Ameya; Rappaport, Carey; Fenneman, Douglas

    2007-02-01

    An analytic model is developed for the time-dependent ultrasound field reflected off a randomly rough vibrating surface for a continuously scanning ultrasound vibrometer system in bistatic configuration. Kirchhoff's approximation to Green's theorem is applied to model the three-dimensional scattering interaction of the ultrasound wave field with the vibrating rough surface. The model incorporates the beam patterns of both the transmitting and receiving ultrasound transducers and the statistical properties of the rough surface. Two methods are applied to the ultrasound system for estimating displacement and velocity amplitudes of an oscillating surface: incoherent Doppler shift spectra and coherent interferometry. Motion of the vibrometer over the randomly rough surface leads to time-dependent scattering noise that causes a randomization of the received signal spectrum. Simulations with the model indicate that surface displacement and velocity estimation are highly dependent upon the scan velocity and projected wavelength of the ultrasound vibrometer relative to the roughness height standard deviation and correlation length scales of the rough surface. The model is applied to determine limiting scan speeds for ultrasound vibrometer measuring ground displacements arising from acoustic or seismic excitation to be used in acoustic landmine confirmation sensing.

  5. Optimum Resolution Bandwidth for Spectral Analysis of Stationary Random Vibration Data

    Directory of Open Access Journals (Sweden)

    Allan G. Piersol

    1993-01-01

    Full Text Available This article presents a methodology for selecting the frequency resolution bandwidth for the spectral analysis of stationary random vibration signals in an optimum manner. Specifically, the resolution bandwidth that will produce power spectral density estimates with a minimum mean square error is determined for any given measurement duration (averaging time, and methods of approximating the optimum bandwidth using practical spectral analysis procedures are detailed. The determination of the optimum resolution bandwidth requires an estimate for the damping ratio of the vibrating structure that produced the measured vibration signal and the analysis averaging time. It is shown that the optimum resolution bandwidth varies approximately with the 0.8 power of the damping ratio and the bandwidth center frequency, and the −0.2 power of the averaging time. Also, any resolution bandwidth within ±50% of the optimum bandwidth will produce power spectral density (PSD estimates with an error that is no more than 25% above the minimum achievable error. If a damping ratio of about 5% for structural resonances is assumed, a constant percentage resolution bandwidth of 1/12 octave, but no less than 2.5 Hz, will provide a near optimum PSD analysis for an averaging time of 2 seconds over the frequency range from 20 to 2000 Hz. A simple scaling formula allows the determination of appropriate bandwidths for other damping ratios and averaging times.

  6. A General Purpose Digital System for Field Vibration Testing

    DEFF Research Database (Denmark)

    Brincker, Rune; Larsen, Jesper Abildgaard; Ventura, Carlos

    2007-01-01

    This paper describes the development and concept implementation of a highly sensitive digital recording system for seismic applications and vibration measurements on large Civil Engineering structures. The system is based on highly sensitive motion transducers that have been used by seismologists...

  7. Equivalent Linearization Analysis of Geometrically Nonlinear Random Vibrations Using Commercial Finite Element Codes

    Science.gov (United States)

    Rizzi, Stephen A.; Muravyov, Alexander A.

    2002-01-01

    Two new equivalent linearization implementations for geometrically nonlinear random vibrations are presented. Both implementations are based upon a novel approach for evaluating the nonlinear stiffness within commercial finite element codes and are suitable for use with any finite element code having geometrically nonlinear static analysis capabilities. The formulation includes a traditional force-error minimization approach and a relatively new version of a potential energy-error minimization approach, which has been generalized for multiple degree-of-freedom systems. Results for a simply supported plate under random acoustic excitation are presented and comparisons of the displacement root-mean-square values and power spectral densities are made with results from a nonlinear time domain numerical simulation.

  8. Vibration test report for in-chimney bracket and instrumented fuel assembly

    Energy Technology Data Exchange (ETDEWEB)

    Ryu, Jeong Soo; Yoon, D. B.; Cho, Y. G.; Ahn, G. H.; Lee, J. H.; Park, J.H

    2000-10-01

    The vibration levels of in-chimney bracket structure which is installed in reactor chimney and instrumented fuel assembly(Type-B Bundle) are investigated under the steady state normal operating condition of the reactor. For this purpose, 4 acceleration data on the guide tube of the instrumented fuel assembly and in-chimney bracket structures subjected to fluid induced vibration are measured. For the analysis of the vibration data, vibration analysis program which can perform basic time and frequency domain analysis, is prepared, and its reliability is verified by comparing the analysis results with those of commercial analysis program(I-DEAS). In time domain analysis, maximum amplitudes, and RMS values of accelerations and displacements from the measured vibration signal, are obtained. The frequency components of the vibration data are analyzed by using the frequency domain analysis. These analysis results show that the levels of the measured vibrations are within the allowable level, and the low frequency component near 10 Hz is dominant in the vibration signal. For the evaluation of the structural integrity on the in-chimney bracket and related structures including the instrumented fuel assembly, the static analysis for ANSYS finite element model is carried out. These analysis results show that the maximum stresses are within the allowable stresses of the ASME code, and the maximum displacement of the top of the flow tube is within the displacement limit. Therefore any damage on the structural integrity is not expected when the irradiation test is performed using the in-chimney bracket.

  9. FIVPET Flow-Induced Vibration Test Report (1) - Candidate Spacer Grid Type I (Optimized H Type)

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Hee; Kang, Heung Seok; Yoon, Kyung Ho; Song, Kee Nam; Kim, Jae Yong

    2006-03-15

    The flow-induced vibration (FIV) test using a 5x5 partial fuel assembly was performed to evaluate mechanical/structural performance of the candidate spacer grid type I (Optimized H shape). From the measured vibration response of the test bundle and the flow parameters, design features of the spacer strap can be analyzed in the point of vibration and hydraulic aspect, and also compared with other spacer strap in simple comparative manner. Furthermore, the FIV test will contributes to understand behaviors of nuclear fuel in operating reactor. The FIV test results will be used to verify the theoretical model of fuel rod and assembly vibration. The aim of this report is to present the results of the FIV test of partial fuel assembly and to introduce the detailed test methodology and analysis procedure. In chapter 2, the overall configuration of test bundle and instrumented tube is remarked and chapter 3 will introduce the test facility (FIVPET) and test section. Chapter 4 deals with overall test condition and procedure, measurement and data acquisition devices, instrumentation equipment and calibration, and error analysis. Finally, test result of vibration and pressure fluctuation is presented and discussed in chapter 5.

  10. Non-stationary random vibration analysis of three-dimensional train-bridge systems

    Science.gov (United States)

    Zhang, Z. C.; Lin, J. H.; Zhang, Y. H.; Howson, W. P.; Williams, F. W.

    2010-04-01

    This paper presents a new non-stationary random vibration technique for the analysis of three-dimensional, time-dependent, train-bridge systems that are subjected to excitations caused by track irregularities. It is based on the pseudo-excitation method (PEM), which was previously applicable only to time-invariant systems, but is extended herein and the result is strictly proven to be applicable to time-dependent systems. The analysis proceeds by taking time lags between the wheel excitations into account, in order that the effects of track irregularity can be regarded as a set of three-dimensional, uniformly modulated, multi-point, different-phase, non-stationary random excitations. This enables the random surface roughness of the track to be transformed using PEM into the superposition of a series of deterministic pseudo-harmonic surface irregularities. The precise integration method is then extended to compute the corresponding pseudo responses. By using these pseudo-responses, various non-stationary random responses, including the time-dependent PSD and RMS of the system, can be obtained conveniently and efficiently. Numerical examples show the effectiveness and accuracy of the present method by comparison with Monte Carlo simulation. Additionally, the characteristics of such non-stationary random responses are discussed.

  11. A General Purpose Digital System for Field Vibration Testing

    OpenAIRE

    Brincker, Rune; Larsen, Jesper Abildgaard; Ventura, Carlos

    2007-01-01

    This paper describes the development and concept implementation of a highly sensitive digital recording system for seismic applications and vibration measurements on large Civil Engineering structures. The system is based on highly sensitive motion transducers that have been used by seismologists and geophysicists for decades. The conventional geophone's ratio of cost to performance, including noise, linearity and dynamic range is unmatched by advanced modern accelerometers. The unit comprise...

  12. Random vibration analysis of axially compressed cylindrical shells under turbulent boundary layer in a symplectic system

    Science.gov (United States)

    Li, Yuyin; Zhang, Yahui; Kennedy, David

    2017-10-01

    A random vibration analysis of an axially compressed cylindrical shell under a turbulent boundary layer (TBL) is presented in the symplectic duality system. By expressing the cross power spectral density (PSD) of the TBL as a Fourier series in the axial and circumferential directions, the problem of structures excited by a random distributed pressure due to the TBL is reduced to solving the harmonic response function, which is the response of structures to a spatial and temporal harmonic pressure of unit magnitude. The governing differential equations of the axially compressed cylindrical shell are derived in the symplectic duality system, and then a symplectic eigenproblem is formed by using the method of separation of variables. Expanding the excitation vector and unknown state vector in symplectic space, decoupled governing equations are derived, and then the analytical solution can be obtained. In contrast to the modal decomposition method (MDM), the present method is formulated in the symplectic duality system and does not need modal truncation, and hence the computations are of high precision and efficiency. In numerical examples, harmonic response functions for the axially compressed cylindrical shell are studied, and a comparison is made with the MDM to verify the present method. Then, the random responses of the shell to the TBL are obtained by the present method, and the convergence problems induced by Fourier series expansion are discussed. Finally, influences of the axial compression on random responses are investigated.

  13. Design and Test of Semi-Active Vibration-Reducing System for Lathe

    Directory of Open Access Journals (Sweden)

    Hongsheng Hu

    2014-09-01

    Full Text Available In this paper, its theory design, analysis and test system of semi-active vibration controlling system used for precision machine have been done. Firstly, lathe bed and spindle entity were modeled by using UG software; Then modes of the machine bed and the key components of spindle were obtained by using ANSYS software; Finally, harmonic response analysis of lathe spindle under complex load was acquired, which provided a basis of MR damper’s structure optimization design for a certain type of precision machine. In order to prove its effectives, a prototype semi-active vibration controlling lathe with MR damper was developed. Tests have been done, and comparison results between passive vibration isolation equipment and semi-active vibration controlling equipment proved its good performances of MR damper.

  14. Nondestructive determination of fatigue crack damage in composites using vibration tests.

    Science.gov (United States)

    Dibenedetto, A. T.; Gauchel, J. V.; Thomas, R. L.; Barlow, J. W.

    1972-01-01

    The vibration response of glass reinforced epoxy and polyester laminates was investigated. The complex modulus and the damping capacity were measured as fatigue crack damage accumulated. Changes in the Young's modulus as well as the damping capacity correlated with the amount of crack damage. The damping was especially sensitive to debonding of the reinforcement from the resin matrix. Measurement of these vibration response changes shows promise as a means to nondestructively test the structural integrity of filament-reinforced composite structural members.

  15. Vibration Mitigation without Dissipative Devices: First Large-Scale Testing of a State Switched Inducer

    Directory of Open Access Journals (Sweden)

    Daniel Tirelli

    2014-01-01

    Full Text Available A new passive device for mitigating cable vibrations is proposed and its efficiency is assessed on 45-meter long taut cables through a series of free and forced vibration tests. It consists of a unilateral spring attached perpendicularly to the cable near the anchorage. Because of its ability to change the cable dynamic behaviour through intermittent activation, the device has been called state switched inducer (SSI. The cable behaviour is shown to be deeply modified by the SSI: the forced vibration response is anharmonicc and substantially reduced in amplitude whereas the free vibration decay is largely sped up through a beating phenomenon. The vibration mitigation effect is mainly due to the activation and coupling of various vibration modes, as evidenced in the response spectra of the equipped cable. This first large-scale experimental campaign shows that the SSI outperforms classical passive devices, thus paving the way to a new kind of low-cost vibration mitigation systems which do not rely on dissipation.

  16. Application of Finite Element Based Simulation and Modal Testing Methods to Improve Vehicle Powertrain Idle Vibration

    Directory of Open Access Journals (Sweden)

    Polat Sendur

    2017-01-01

    Full Text Available Current practice of analytical and test methods related to the analysis, testing and improvement of vehicle vibrations is overviewed. The methods are illustrated on the determination and improvement of powertrain induced steering wheel vibration of a heavy commercial truck. More specifically, the transmissibility of powertrain idle vibration to cabin is investigated with respect to powertrain rigid body modes and modal alignment of the steering column/wheel system is considered. It is found out that roll mode of the powertrain is not separated from idle excitation for effective vibration isolation as well as steering wheel column mode is close to the 3rd engine excitation frequency order, which results in high vibration levels. Powertrain roll mode is optimized by tuning the powertrain mount stiffness to improve the performance. Steering column mode is also separated from the 3rd engine excitation frequency by the application of a mass absorber. It is concluded that the use of analytical and test methods to address the complex relation between design parameters and powertrain idle response is effective to optimize the system performance and evaluate the trade-offs in the vehicle design such as vibration performance and weight. Reference Number: www.asrongo.org/doi:4.2017.2.1.10

  17. Numerical methods for acquisition and analysis of vibration tests; Methodes numeriques d'acquisition et de depouillement d'essais aux vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Badel, D.; Cocchi, G.; Oules, H. [Centre d' Etudes Scientifiques et Techniques d' Aquitaine (France). Centre d' Etudes Nucleaires

    1969-07-01

    The S.I.D.E.X. is a digital computer assisted facility for Data acquisition and Data processing. It is designed for sine wave or random environment tests, mechanical or acoustical vibrations, shock waves. The mathematical principles and the system configuration have been described in the CEA file nb R-3666. The present one describes the numerical methods and the programs available up to now. Some examples of results obtained are shown at the end. (authors) [French] Le systeme integre de depouillement pour l'experimentation S.I.D.E.X., a pour but d'effectuer les calibration, les acquisitions et les depouillements des essais aux vibrations sinusoidales ou aleatoires, mecaniques ou acoustiques et des essais de chocs. Les methodes mathematiques correspondantes et la configuration digitale employee ont ete decrites dans le rapport CEA nb CEA-R-3666. Le present rapport indique les methodes numeriques en vigueur et les programmes actuellement disponibles. Des exemples de resultats obtenus sont egalement presentes. (auteurs)

  18. Developing Uncertainty Models for Robust Flutter Analysis Using Ground Vibration Test Data

    Science.gov (United States)

    Potter, Starr; Lind, Rick; Kehoe, Michael W. (Technical Monitor)

    2001-01-01

    A ground vibration test can be used to obtain information about structural dynamics that is important for flutter analysis. Traditionally, this information#such as natural frequencies of modes#is used to update analytical models used to predict flutter speeds. The ground vibration test can also be used to obtain uncertainty models, such as natural frequencies and their associated variations, that can update analytical models for the purpose of predicting robust flutter speeds. Analyzing test data using the -norm, rather than the traditional 2-norm, is shown to lead to a minimum-size uncertainty description and, consequently, a least-conservative robust flutter speed. This approach is demonstrated using ground vibration test data for the Aerostructures Test Wing. Different norms are used to formulate uncertainty models and their associated robust flutter speeds to evaluate which norm is least conservative.

  19. Vibration Analysis of Randomly Oriented Carbon Nanotube Based on FGM Beam Using Timoshenko Theory

    Directory of Open Access Journals (Sweden)

    Mohammad Amin Rashidifar

    2015-02-01

    Full Text Available The carbon nanotube (CNT reinforced functionally graded materials (FGM are expected to be the new generation materials having wide range of unexplored potential applications in various technological areas such as aerospace and structural and chemical industry. The present work deals with the finite element modeling and free vibration analysis of CNT based functionally graded beam using three-dimensional Timoshenko beam theory. It has been assumed that the material properties of CNT based FG beam vary only along the thickness and these properties are evaluated by rule of mixture. The extended Hamilton principle has been applied to find out the governing equations of CNT based FG beam. Finite element method is used to solve governing equation with the exact shape functions. Initial analysis deals with CNTs assumed to be oriented along the length direction only. But practically it is not possible. So, further work deals with the free vibration analysis of functionally graded nanocomposite beams reinforced by randomly oriented straight single walled carbon nanotubes (SWCNTs. The Eshelby-Mori-Tanaka approach based on an equivalent fiber is used to investigate the material properties of the beam. Results are presented in tabular and graphical forms to show the effects of carbon nanotube orientations, slenderness ratios, and boundary conditions on the dynamic behavior of the beam.

  20. An Analytical Solution for Predicting the Vibration-Fatigue-Life in Bimodal Random Processes

    Directory of Open Access Journals (Sweden)

    Chaoshuai Han

    2017-01-01

    Full Text Available Predicting the vibration-fatigue-life of engineering structures subjected to random loading is a critical issue for. Frequency methods are generally adopted to deal with this problem. This paper focuses on bimodal spectra methods, including Jiao-Moan method, Fu-Cebon method, and Modified Fu-Cebon method. It has been proven that these three methods can give acceptable fatigue damage results. However, these three bimodal methods do not have analytical solutions. Jiao-Moan method uses an approximate solution, Fu-Cebon method, and Modified Fu-Cebon method needed to be calculated by numerical integration which is obviously not convenient in engineering application. Thus, an analytical solution for predicting the vibration-fatigue-life in bimodal spectra is developed. The accuracy of the analytical solution is compared with numerical integration. The results show that a very good agreement between an analytical solution and numerical integration can be obtained. Finally, case study in offshore structures is conducted and a bandwidth correction factor is computed through using the proposed analytical solution.

  1. Accelerated lifetime test of vibration isolator made of Metal Rubber material

    Science.gov (United States)

    Ao, Hongrui; Ma, Yong; Wang, Xianbiao; Chen, Jianye; Jiang, Hongyuan

    2017-01-01

    The Metal Rubber material (MR) is a kind of material with nonlinear damping characteristics for its application in the field of aerospace, petrochemical industry and so on. The study on the lifetime of MR material is impendent to its application in engineering. Based on the dynamic characteristic of MR, the accelerated lifetime experiments of vibration isolators made of MR working under random vibration load were conducted. The effects of structural parameters of MR components on the lifetime of isolators were studied and modelled with the fitting curves of degradation data. The lifetime prediction methods were proposed based on the models.

  2. Random Vibration Analysis of Train Moving over Slab Track on Bridge under Track Irregularities and Earthquakes by Pseudoexcitation Method

    Directory of Open Access Journals (Sweden)

    Zhiping Zeng

    2015-01-01

    Full Text Available This paper investigates the random vibration and the dynamic reliability of operation stability of train moving over slab track on bridge under track irregularities and earthquakes by the pseudoexcitation method (PEM. Each vehicle is modeled by multibody dynamics. The track and bridge is simulated by a rail-slab-girder-pier interaction finite element model. The coupling equations of motion are established based on the wheel-rail interaction relationship. The random excitations of the track irregularities and seismic accelerations are transformed into a series of deterministic pseudoexcitations by PEM. The time-dependent power spectral densities (PSDs of the random vibration of the system are obtained by step-by-step integration method, and the corresponding dynamic reliability is estimated based on the first-passage failure criterion. A case study is then presented in which a high-speed train moves over a slab track resting on a simply supported girder bridge. The PSD characteristics of the random vibration of the bridge and train are analyzed, the influence of the wheel-rail-bridge interaction models on the random vibration of the bridge and train is discussed, and furthermore the influence of train speed, earthquake intensity, and pier height on the dynamic reliability of train operation stability is studied.

  3. A Randomized Controlled Pilot Study to Investigate the Effect of Whole-Body Vibration on Lower-Extremity Fatigue.

    Science.gov (United States)

    Ansari, Noureddin Nakhostin; Naghdi, Soofia; Karimi-Zarchi, Hadi; Fakhari, Zahra; Hasson, Scott

    2017-09-01

    Whole-body vibration (WBV) is a type of weight-bearing exercise used in the field of sport and rehabilitation. There is no study on the effects of WBV on muscle recovery after a fatiguing activity. To determine the effects of a single WBV session on lower-extremity fatigue. Randomized controlled pilot study. University Physiotherapy Clinic. A total of 13 healthy young men volunteered to participate in this study. Subjects were randomly assigned into the WBV group (n = 7, mean age: 21 y) or control group (CG; n = 6, mean age: 20 y). Subjects in the WBV group participated in a single-session WBV (30 Hz, amplitude 4 mm, 2 min) after lower-extremity fatigue. Peak force of quadriceps muscle, single leg hop test, and Y-test were measured before inducing muscle fatigue (T0), immediately after completing the fatigue protocol (T1), after WBV (T2), and 15 min following the application of WBV (T3). The same method was applied in the CG while the WBV machine was turned off. Repeated-measure ANOVA revealed no significant differences between groups in any of the outcomes. The findings indicated that WBV was not effective in the recovery of lower-extremity fatigue in healthy young men.

  4. Ground vibration test results for Drones for Aerodynamic and Structural Testing (DAST)/Aeroelastic Research Wing (ARW-1R) aircraft

    Science.gov (United States)

    Cox, T. H.; Gilyard, G. B.

    1986-01-01

    The drones for aerodynamic and structural testing (DAST) project was designed to control flutter actively at high subsonic speeds. Accurate knowledge of the structural model was critical for the successful design of the control system. A ground vibration test was conducted on the DAST vehicle to determine the structural model characteristics. This report presents and discusses the vibration and test equipment, the test setup and procedures, and the antisymmetric and symmetric mode shape results. The modal characteristics were subsequently used to update the structural model employed in the control law design process.

  5. Approximations to the Probability of Failure in Random Vibration by Integral Equation Methods

    DEFF Research Database (Denmark)

    Nielsen, Søren R.K.; Sørensen, John Dalsgaard

    Close approximations to the first passage probability of failure in random vibration can be obtained by integral equation methods. A simple relation exists between the first passage probability density function and the distribution function for the time interval spent below a barrier before...... outcrossing. An integral equation for the probability density function of the time interval is formulated, and adequate approximations for the kernel are suggested. The kernel approximation results in approximate solutions for the probability density function of the time interval, and hence for the first...... passage probability density. The results of the theory agree well with simulation results for narrow banded processes dominated by a single frequency, as well as for bimodal processes with 2 dominating frequencies in the structural response....

  6. Harnessing data structure for recovery of randomly missing structural vibration responses time history: Sparse representation versus low-rank structure

    Science.gov (United States)

    Yang, Yongchao; Nagarajaiah, Satish

    2016-06-01

    Randomly missing data of structural vibration responses time history often occurs in structural dynamics and health monitoring. For example, structural vibration responses are often corrupted by outliers or erroneous measurements due to sensor malfunction; in wireless sensing platforms, data loss during wireless communication is a common issue. Besides, to alleviate the wireless data sampling or communication burden, certain accounts of data are often discarded during sampling or before transmission. In these and other applications, recovery of the randomly missing structural vibration responses from the available, incomplete data, is essential for system identification and structural health monitoring; it is an ill-posed inverse problem, however. This paper explicitly harnesses the data structure itself-of the structural vibration responses-to address this (inverse) problem. What is relevant is an empirical, but often practically true, observation, that is, typically there are only few modes active in the structural vibration responses; hence a sparse representation (in frequency domain) of the single-channel data vector, or, a low-rank structure (by singular value decomposition) of the multi-channel data matrix. Exploiting such prior knowledge of data structure (intra-channel sparse or inter-channel low-rank), the new theories of ℓ1-minimization sparse recovery and nuclear-norm-minimization low-rank matrix completion enable recovery of the randomly missing or corrupted structural vibration response data. The performance of these two alternatives, in terms of recovery accuracy and computational time under different data missing rates, is investigated on a few structural vibration response data sets-the seismic responses of the super high-rise Canton Tower and the structural health monitoring accelerations of a real large-scale cable-stayed bridge. Encouraging results are obtained and the applicability and limitation of the presented methods are discussed.

  7. A New Large Vibration Test Facility Concept for the James Webb Space Telescope

    Science.gov (United States)

    Ross, Brian P.; Johnson, Eric L.; Hoksbergen, Joel; Lund, Doug

    2014-01-01

    The James Webb Space Telescope consists of three main components, the Integrated Science Instrument Module (ISIM) Element, the Optical Telescope Element (OTE), and the Spacecraft Element. The ISIM and OTE are being assembled at the National Aeronautics and Space Administration's Goddard Spaceflight Center (GSFC). The combined OTE and ISIM Elements, called OTIS, will undergo sine vibration testing before leaving Goddard. OTIS is the largest payload ever tested at Goddard and the existing GSFC vibration facilities are incapable of performing a sine vibration test of the OTIS payload. As a result, a new large vibration test facility is being designed. The new facility will consist of a vertical system with a guided head expander and a horizontal system with a hydrostatic slip table. The project is currently in the final design phase with installation to begin in early 2015 and the facility is expected to be operational by late 2015. This paper will describe the unique requirements for a new large vibration test facility and present the selected final design concepts.

  8. Integrated Advanced Microwave Sounding Unit-A (AMSU-A) METOP Stress Analysis Report (Qual Level Random Vibration) A1 Module

    Science.gov (United States)

    Mehitretter, R.

    1996-01-01

    Stress analysis of the primary structure of the Meteorological Satellites Project (METSAT) Advanced Microwave Sounding Units-A, A1 Module performed using the Meteorological Operational (METOP) Qualification Level 9.66 grms Random Vibration PSD Spectrum is presented. The random vibration structural margins of safety and natural frequency predictions are summarized.

  9. Shock and vibration tests of uranium mononitride fuel pellets for a space power nuclear reactor

    Science.gov (United States)

    Adams, D. W.

    1972-01-01

    Shock and vibration tests were conducted on cylindrically shaped, depleted, uranium mononitride (UN) fuel pellets. The structural capabilities of the pellets were determined under exposure to shock and vibration loading which a nuclear reactor may encounter during launching into space. Various combinations of diametral and axial clearances between the pellets and their enclosing structures were tested. The results of these tests indicate that for present fabrication of UN pellets, a diametral clearance of 0.254 millimeter and an axial clearance of 0.025 millimeter are tolerable when subjected to launch-induced loads.

  10. Vibration of the soil caused by a vehicle moving over the randomly uneven surface of a slab track

    OpenAIRE

    Grundmann, H.;Lenz, St.

    2012-01-01

    A vehicle which passes an uneven surface of a slab track causes vibrations of the whole system: the vehicle, the slab track and the subsoil. For a given random unevenness ?w of the slab track surface, covariances of the soil surface motion are calculated.

  11. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: AMSU-A1 EOS Instrument, (S/N 202) Qualification Level Vibration Tests of August/September 1998, (S/O 565632, OC-417) Plus Addendum A

    Science.gov (United States)

    Heffer, R.

    1998-01-01

    The purpose of this report is to present a qualification level vibration testing performed on the S/N 202, EOS AMSU-A1 Instrument was vibration tested to qualification levels per the Ref. 1 shop order. The instrument withstood the 8 g sine sweep test, the 7.5 Grms random vibration test, and the 18.75 g sine burst test in each of the three orthogonal axes. Some loss of transmissibility, however, is seen in the lower reflector after Z-axis random vibration. The test sequence was not without incidence. Failure of Channel 7 in the Limited Performance Test (LPT) performed after completion of the 1 st (X-axis) axis vibration sequence, required replacement of the DRO and subsequent re-testing of the instrument. The post-vibration comprehensive performance test (CPT) was successfully run after completion of the three axes of vibration with the replacement component installed in the instrument. Passing the CPT signified the successful completion of the S/N 202 A1 qualification vibration testing.

  12. Technical Road Testing of the 18,000 BTU Air Conditioners (Vibration Profile)

    Science.gov (United States)

    1990-06-27

    equimped with a calibrated fifth wheel driven speedanetr. Instrumented testing was crducted on the Mzso area izproved gravel road, Belgian block, two...item, conducting the test, and acquiring and processing all test data. 1.5 SYSTEM DESCRIPTION Two 50/60 Hz, 3-2hase, 208-volt, 18,000 BTU/hr compact...operationally checked periodically and at the conclusion of the road vibration test. A limited amount of data processing was performed at the test

  13. Whole Body Vibration Exercise Protocol versus a Standard Exercise Protocol after ACL Reconstruction: A Clinical Randomized Controlled Trial with Short Term Follow-Up

    Directory of Open Access Journals (Sweden)

    Gereon Berschin

    2014-09-01

    Full Text Available The suitability and effectiveness of whole body vibration (WBV exercise in rehabilitation after injury of the anterior cruciate ligament (ACL was studied using a specially designed WBV protocol. We wanted to test the hypothesis if WBV leads to superior short term results regarding neuromuscular performance (strength and coordination and would be less time consuming than a current standard muscle strengthening protocol. In this prospective randomized controlled clinical trial, forty patients who tore their ACL and underwent subsequent ligament reconstruction were enrolled. Patients were randomized to the whole body vibration (n=20 or standard rehabilitation exercise protocol (n=20. Both protocols started in the 2nd week after surgery. Isometric and isokinetic strength measurements, clinical assessment, Lysholm score, neuromuscular performance were conducted weeks 2, 5, 8 and 11 after surgery. Time spent for rehabilitation exercise was reduced to less than a half in the WBV group. There were no statistically significant differences in terms of clinical assessment, Lysholm score, isokinetic and isometric strength. The WBV group displayed significant better results in the stability test. In conclusion, preliminary data indicate that our whole body vibration muscle exercise protocol seems to be a good alternative to a standard exercise program in ACL-rehabilitation. Despite of its significant reduced time requirement it is at least equally effective compared to a standard rehabilitation protocol.

  14. Random Vibration Analysis of Train Moving over Slab Track on Bridge under Track Irregularities and Earthquakes by Pseudoexcitation Method

    OpenAIRE

    Zeng, Zhiping; Zhu, Kunteng; He, Xianfeng; Xu, Wentao; Chen, Lingkun; Lou, Ping

    2015-01-01

    This paper investigates the random vibration and the dynamic reliability of operation stability of train moving over slab track on bridge under track irregularities and earthquakes by the pseudoexcitation method (PEM). Each vehicle is modeled by multibody dynamics. The track and bridge is simulated by a rail-slab-girder-pier interaction finite element model. The coupling equations of motion are established based on the wheel-rail interaction relationship. The random excitations of the track i...

  15. Short-Term Effects of Whole-Body Vibration Combined with Task-Related Training on Upper Extremity Function, Spasticity, and Grip Strength in Subjects with Poststroke Hemiplegia: A Pilot Randomized Controlled Trial.

    Science.gov (United States)

    Lee, Jung-Sun; Kim, Chang-Yong; Kim, Hyeong-Dong

    2016-08-01

    The aim of this study was to determine the effect of whole-body vibration training combined with task-related training on arm function, spasticity, and grip strength in subjects with poststroke hemiplegia. Forty-five subjects with poststroke were randomly allocated to 3 groups, each with 15 subjects as follows: control group, whole-body vibration group, and whole-body vibration plus task-related training group. Outcome was evaluated by clinical evaluation and measurements of the grip strength before and 4 weeks after intervention. Our results show that there was a significantly greater increase in the Fugl-Meyer scale, maximal grip strength of the affected hand, and grip strength normalized to the less affected hand in subjects undergoing the whole-body vibration training compared with the control group after the test. Furthermore, there was a significantly greater increase in the Wolf motor function test and a decrease in the modified Ashworth spasticity total scores in subjects who underwent whole-body vibration plus task-related training compared with those in the other 2 groups after the test. The findings indicate that the use of whole-body vibration training combined with task-related training has more benefits on the improvement of arm function, spasticity, and maximal grip strength than conventional upper limb training alone or with whole-body vibration in people with poststroke hemiplegia.

  16. The effect of vibration therapy on spasticity and motor function in children with cerebral palsy: a randomized controlled trial.

    Science.gov (United States)

    Katusic, Ana; Alimovic, Sonja; Mejaski-Bosnjak, Vlatka

    2013-01-01

    As the motor system relies heavily on deep sensory stimulation, recent studies have investigated the effect of vibration stimuli. Although research suggests a positive influence of vibration on motor performance in individuals with neurological disorders, there are very limited numbers of studies in children with cerebral palsy (CP). The objective of the present study was to evaluate the effects of sound wave vibration therapy on spasticity and motor function in children with CP. In this 3-month trial, 89 children with spastic CP were randomized to either continue their physiotherapy treatment (PT) or to receive vibration therapy twice a week in addition to their PT program. The randomization was stratified according to the Gross Motor Function Classification System (GMFCS) level to ensure similar functional ability. Children were assessed at baseline and after the 12-week intervention period. The outcomes measured were spasticity level as assessed by Modified Modified Ashworth Scale (MMAS) and gross motor function as assessed by Gross Motor Function Measurement (GMFM-88). Subgroup analysis was performed for the GMFCS. Significant differences between groups were detected for changes in spasticity level and gross motor function after the three months intervention. In conclusion, vibration therapy may decrease spasticity and improve motor performance in children with CP. The results of the present trial serve as valuable input for evidence-based treatments in paediatric neurorehabilitation.

  17. Semi-active vibration control in cable-stayed bridges under the condition of random wind load

    Science.gov (United States)

    Heo, G.; Joonryong, Jeon

    2014-07-01

    This paper aims at an experimental study on the real-time vibration control of bridge structures using a semi-active vibration control method that has been in the spotlight recently. As structures are becoming larger and larger, structural harmful vibration caused by unspecified external forces such as earthquakes, gusts of wind, and collisions has been brought to attention as an important issue. These harmful vibrations can cause not only user anxiety but also severe structural damage or even complete failure of structures. Therefore, in view of structural safety and economical long-term maintenance, real-time control technology of the harmful structural vibration is urgently required. In this paper, a laboratory-scale model of a cable-stayed bridge was built, and a shear-type MR damper and a semi-active vibration control algorithm (Lyapunov and clipped optimal) were applied for the control of harmful vibration of the model bridge, in real time. On the basis of the test results, each semi-active control algorithm was verified quantitatively.

  18. Whole body vibration exercise for chronic low back pain: study protocol for a single-blind randomized controlled trial

    Science.gov (United States)

    2014-01-01

    Background Low back pain affects approximately 80% of people at some stage in their lives. Exercise therapy is the most widely used nonsurgical intervention for low back pain in practice guidelines. Whole body vibration exercise is becoming increasingly popular for relieving musculoskeletal pain and improving health-related quality of life. However, the efficacy of whole body vibration exercise for low back pain is not without dispute. This study aims to estimate the effect of whole body vibration exercise for chronic low back pain. Methods/Design We will conduct a prospective, single-blind, randomized controlled trial of 120 patients with chronic low back pain. Patients will be randomly assigned into an intervention group and a control group. The intervention group will participate in whole body vibration exercise twice a week for 3 months. The control group will receive general exercise twice a week for 3 months. Primary outcome measures will be the visual analog scale for pain, the Oswestry Disability Index and adverse events. The secondary outcome measures will include muscle strength and endurance of spine, trunk proprioception, transversus abdominis activation capacity, and quality of life. We will conduct intention-to-treat analysis if any participants withdraw from the trial. Discussion Important features of this study include the randomization procedures, single-blind, large sample size, and a standardized protocol for whole body vibration in chronic low back pain. This study aims to determine whether whole body vibration exercise produces more beneficial effects than general exercise for chronic low back pain. Therefore, our results will be useful for patients with chronic low back pain as well as for medical staff and health-care decision makers. Trial registration Chinese Clinical Trial Registry: ChiCTR-TRC-13003708. PMID:24693945

  19. A Coupling Vibration Test Bench and the Simulation Research of a Maglev Vehicle

    Directory of Open Access Journals (Sweden)

    Weihua Ma

    2015-01-01

    Full Text Available To study the characteristics of the coupling vibration between a maglev vehicle and its track beam system and to improve the performance of the levitation system, a new type of vibration test bench was developed. Take a single maglev frame as the study object; simulation of the coupling vibration of the maglev vehicle, levitation system, and track beam were achieved. In addition, all types of real track irregularity excitations can be simulated using hydraulic actuators of the test bench. To expand the research scope, a simulation model was developed that can conduct the simulation research synergistically with the test bench. Based on a dynamics model of the test bench, the dynamics simulation method determined the influence on the levitation control performance of three factors: the track beam support stiffness, the track beam mass, and the track irregularity. The vibration resonance phenomenon of the vehicle/track system was reproduced by the dynamics simulation, and a portion of the simulation results were validated by the test results. By combining the test bench and the dynamics model, experiments can be guided by the simulation results, and the experimental results can validate the dynamics simulation results.

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

    Directory of Open Access Journals (Sweden)

    Kyung-Won Min

    2013-01-01

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

  1. Numerical Simulation of Vertical Random Vibration of Train-Slab Track-Bridge Interaction System by PEM

    Directory of Open Access Journals (Sweden)

    Zhi-ping Zeng

    2014-01-01

    Full Text Available The paper describes the numerical simulation of the vertical random vibration of train-slab track-bridge interaction system by means of finite element method and pseudoexcitation method. Each vehicle is modeled as four-wheelset mass-spring-damper system with two-layer suspension systems. The rail, slab, and bridge girder are modeled by three-layer elastic Bernoulli-Euler beams connected with each other by spring and damper elements. The equations of motion for the entire system are derived according to energy principle. By regarding rail irregularity as a series of multipoint, different-phase random excitations, the random load vectors of the equations of motion are obtained by pseudoexcitation method. Taking a nine-span simply supported beam bridge traveled by a train consisting of 8 vehicles as an example, the vertical random vibration responses of the system are investigated. Firstly, the suitable number of discrete frequencies of rail irregularity is obtained by numerical experimentations. Secondly, the reliability and efficiency of pseudoexcitation method are verified through comparison with Monte Carlo method. Thirdly, the random vibration characteristics of train-slab track-bridge interaction system are analyzed by pseudoexcitation method. Finally, applying the 3σ rule for Gaussian stochastic process, the maximum responses of train-slab track-bridge interaction system with respect to various train speeds are studied.

  2. Design and Performance Testing of a Novel Three-Dimensional Elliptical Vibration Turning Device

    Directory of Open Access Journals (Sweden)

    Jieqiong Lin

    2017-10-01

    Full Text Available A novel three-dimensional (3D elliptical vibration turning device which is on the basis of the leaf-spring-flexure-hinges-based (LSFH-based double parallel four-bar linkages (DPFLMs has been proposed. In order to evaluate the performance of the developed 3D elliptical vibration cutting generator (EVCG, the off-line tests were carried out to investigate the stroke, dynamic performance, resolution, tracking accuracy and hysteresis along the three vibration axes. Experimental results indicate that the maximum stroke of three vibration axes can reach up to 26 μm. The working bandwidth can reach up to 1889 Hz. The resolution and hysteresis tests show that the developed 3D EVCG has a good tracking accuracy, relative high resolution and low hysteresis, which is appropriate for micro/nano machining. Kinematical modeling is carried out to investigate the tool vibration trajectory. Experimental results shown that the simulation results agree well with the experimental one, which indicate that the developed 3D EVCG can be used as an option for micro/nano machining.

  3. Fixed Base Modal Testing Using the NASA GRC Mechanical Vibration Facility

    Science.gov (United States)

    Staab, Lucas D.; Winkel, James P.; Suarez, Vicente J.; Jones, Trevor M.; Napolitano, Kevin L.

    2016-01-01

    The Space Power Facility at NASA's Plum Brook Station houses the world's largest and most powerful space environment simulation facilities, including the Mechanical Vibration Facility (MVF), which offers the world's highest-capacity multi-axis spacecraft shaker system. The MVF was designed to perform sine vibration testing of a Crew Exploration Vehicle (CEV)-class spacecraft with a total mass of 75,000 pounds, center of gravity (cg) height above the table of 284 inches, diameter of 18 feet, and capability of 1.25 gravity units peak acceleration in the vertical and 1.0 gravity units peak acceleration in the lateral directions. The MVF is a six-degree-of-freedom, servo-hydraulic, sinusoidal base-shake vibration system that has the advantage of being able to perform single-axis sine vibration testing of large structures in the vertical and two lateral axes without the need to reconfigure the test article for each axis. This paper discusses efforts to extend the MVF's capabilities so that it can also be used to determine fixed base modes of its test article without the need for an expensive test-correlated facility simulation.

  4. An inverse method for the identification of a distributed random excitation acting on a vibrating structure. Theory

    Energy Technology Data Exchange (ETDEWEB)

    Granger, S.; Perotin, L. [Electricite de France (EDF), 78 - Chatou (France)

    1997-12-31

    Maintaining the PWR components under reliable operating conditions requires a complex design to prevent various damaging processes, including fatigue and wear problems due to flow-induced vibration. In many practical situations, it is difficult, if not impossible, to perform direct measurements or calculations of the external forces acting on vibrating structures. Instead, vibrational responses can often be conveniently measured. This paper presents an inverse method for estimating a distributed random excitation from the measurement of the structural response at a number of discrete points. This paper is devoted to the presentation of the theoretical development. The force identification method is based on a modal model for the structure and a spatial orthonormal decomposition of the excitation field. The estimation of the Fourier coefficients of this orthonormal expansion is presented. As this problem turns out to be ill-posed, a regularization process is introduced. The minimization problem associated to this process is then formulated and its solutions is developed. (author) 17 refs.

  5. Wind-Tunnel Tests of a Bridge Model with Active Vibration Control

    DEFF Research Database (Denmark)

    Hansen, H. I.; Thoft-Christensen, Palle; Mendes, P. A.

    The application of active control systems to reduce wind vibrations in bridges is a new area of research. This paper presents the results that were obtained on a set of wind tunnel tests of a bridge model equipped with active movable flaps. Based on the monitored position and motion of the deck...

  6. Bioelectrical activity of the pelvic floor muscles during synchronous whole-body vibration--a randomized controlled study.

    Science.gov (United States)

    Stania, Magdalena; Chmielewska, Daria; Kwaśna, Krystyna; Smykla, Agnieszka; Taradaj, Jakub; Juras, Grzegorz

    2015-10-24

    More and more frequently stress urinary incontinence affects young healthy women. Hence, early implementation of effective preventive strategies in nulliparous continent women is essential, including pelvic floor muscle training. An initial evaluation based on the bioelectrical activity of the pelvic floor muscles (PFM) during whole-body vibration (WBV) would help to devise the best individualized training for prevention of stress urinary incontinence in woman. We hypothesized that synchronous WBV enhances bioelectrical activity of the PFM which depends on vibration frequency and peak-to-peak vibration displacement. The sample consisted of 36 nulliparous continent women randomly allocated to three comparative groups. Group I and II subjects participated in synchronous whole-body vibrations on a vibration platform; the frequency and peak-to-peak displacement of vibration were set individually for each group. Control participants performed exercises similar to those used in the study groups but without the concurrent application of vibrations. Pelvic floor surface electromyography (sEMG) activity was recorded using a vaginal probe during three experimental trials limited to 30s, 60s and 90 s. The mean amplitude and variability of the signal were normalized to the Maximal Voluntary Contraction - MVC. Friedman's two-way ANOVA revealed a statistically significant difference in the mean normalized amplitudes (%MVC) of the sEMG signal from the PFM during 60s- and 90 s-trials between the group exposed to high-intensity WBV and control participants (p pelvic floor muscle fatigue. The trial was registered in the Australian and New Zealand Clinical Trials Registry (no. ACTRN12615000966594); registration date: 15/09/2015.

  7. Vibration test on KMRR reactor structure and primary cooling system piping

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Seung Hoh; Kim, Tae Ryong; Park, Jin Hoh; Park, Jin Suk; Ryoo, Jung Soo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1994-10-01

    Most equipments, piping systems and reactor structures in nuclear power plants are subjected to flow induced vibration due to high temperature and high pressure coolant flowing inside or outside of the equipments, systems and structures. Because the flow induced vibration sometimes causes significant damage to reactor structures and piping systems, it is important and necessary to evaluate the vibration effect on them and to prove their structural integrity. Korea Multipurpose Research Reactor (KMRR) being constructed by KAERI is 30 MWt pool type research reactor. Since its main structures and piping systems were designed and manufactured in accordance with the standards and guidelines for commercial nuclear power plant, it was decided to evaluate their vibratory response in accordance with the standards and guidelines for commercial NPP. The objective of this vibration test is the assessment of vibration levels of KMRR reactor structure and primary cooling piping system for their structural integrity under the steady-state or transient operating condition. 38 figs, 14 tabs, 2 refs. (Author).

  8. Lessons learned from CIRFT testing on SNF vibration integrity study

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Hong [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Jiang, Hao [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Bevard, Bruce Balkcom [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Howard, Rob L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Scaglione, John M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-01-01

    A cyclic integrated reversible-bending fatigue tester (CIRFT) was developed to support U.S. NRC and DOE Used Fuel Disposition Campaign studies on high burn-up (HBU) spent nuclear fuel (SNF) transportation during normal conditions of transport (NCT). Two devices were developed; the first CIRFT was successfully installed and operated in the ORNL hot-cells in September 2013. Since hot cell testing commenced several HBU SNF samples from both Zr-4 and M5 clads were investigated. The second CIRFT device was developed in February 2014, and has been used to test clad/fuel surrogate rods (stainless steel with alumina pellet inserts). The second CIRFT machine has also been used for sensor development and test sensitivity analyses, as well as loading boundary condition parameter studies. The lessons learned from CIRFT testing will be presented in this paper.

  9. Random Vibration Suppression of a Truss Core Sandwich Panel Using Independent Modal Resonant Shunt and Modal Criterion

    Directory of Open Access Journals (Sweden)

    Kongming Guo

    2017-05-01

    Full Text Available The aim of this paper is to suppress the random spatial vibration of the face sheet of a lightly damped truss core sandwich panel structure. Because broad-bandwidth vibration energy is concentrated in resonance peaks for lightly damped structures, an independent modal resonant shunt control method is utilized to add damping ratios to the chosen modes. In this method, each piezoelectric transducer is connected to a single resonant shunt which is tuned to control the vibration of a single mode. An H2 norm sensitivity-based modal criterion is proposed in order to determine which modes to control under a given bandwidth of excitation and input-output condition. Numerical simulation is implemented while control strategies with different controlled modes are compared. The result shows that the independent modal resonant shunt control method can suppress random vibration response of the face sheet by using only a few piezoelectric transducers, and the proposed modal criterion can be used to determine which modes to control.

  10. Early vibration assisted physiotherapy in toddlers with cerebral palsy - a randomized controlled pilot trial.

    Science.gov (United States)

    Stark, C; Herkenrath, P; Hollmann, H; Waltz, S; Becker, I; Hoebing, L; Semler, O; Hoyer-Kuhn, H; Duran, I; Hero, B; Hadders-Algra, M; Schoenau, E

    2016-09-07

    to investigate feasibility, safety and efficacy of home-based side-alternating whole body vibration (sWBV) to improve motor function in toddlers with cerebral palsy (CP). Randomized controlled trial including 24 toddlers with CP (mean age 19 months (SD±3.1); 13 boys). 14 weeks sWBV with ten 9-minute sessions weekly (non-individualized). Group A started with sWBV, followed by 14 weeks without; in group B this order was reversed. Feasibility (≥70% adherence) and adverse events were recorded; efficacy evaluated with the Gross Motor Function Measure (GMFM-66), Pediatric Evaluation of Disability Inventory (PEDI), at baseline (T0), 14 (T1) and 28 weeks (T2). Developmental change between T0 and T1 was similar in both groups; change scores in group A and B: GMFM-66 2.4 (SD±2.1) and 3.3 (SD±2.9) (p=0.412); PEDI mobility 8.4 (SD±6.6) and 3.5 (SD±9.2) (p=0.148), respectively. In two children muscle tone increased post-sWBV. 24 children received between 67 and 140 sWBV sessions, rate of completed sessions ranged from 48 to 100% and no dropouts were observed. A 14-week home-based sWBV intervention was feasible and safe in toddlers with CP, but was not associated with improvement in gross motor function.

  11. Fatigue Failure Results for Multi-Axial versus Uniaxial Stress Screen Vibration Testing

    Directory of Open Access Journals (Sweden)

    Wayne E. Whiteman

    2002-01-01

    Full Text Available To date, the failure potential and prediction between simultaneous multi-axial versus sequentially applied uniaxial vibration stress screen testing has been the subject of great debate. In most applications, current vibration tests are done by sequentially applying uniaxial excitation to the test specimen along three orthogonal axes. The most common standards for testing military equipment are published in MIL-STD-810F and NAVMAT P-9492. Previous research had shown that uniaxial testing may be unrealistic and inadequate. This current research effort is a continuing effort to systematically investigate the differences between fatigue damage mechanisms and the effects of uniaxial versus tri-axial testing. This includes assessing the ability of the tri-axial method in predicting the formation of damage mechanisms, specifically looking at the effects of stress or fatigue failure. Multi-axial testing achieves the synergistic effect of exciting all modes simultaneously and induces a more realistic vibration stress loading condition. As such, it better approximates real-world operating conditions. This paper provides the latest results on the differences between multi-axial and uniaxial testing of a simple notched cantilever beam.

  12. Design of Accelerated Reliability Test for CNC Motorized Spindle Based on Vibration Signal

    Directory of Open Access Journals (Sweden)

    Chen Chao

    2016-01-01

    Full Text Available Motorized spindle is the key functional component of CNC machining centers which is a mechatronics system with long life and high reliability. The reliability test cycle of motorized spindle is too long and infeasible. This paper proposes a new accelerated test for reliability evaluation of motorized spindle. By field reliability test, authors collect and calculate the load data including rotational speed, cutting force and torque. Load spectrum distribution law is analyzed. And authors design a test platform to apply the load spectrum. A new method to define the fuzzy acceleration factor based on the vibration signal is proposed. Then the whole test plan of accelerated reliability test is done.

  13. Vertical Random Vibration Analysis of Track-Subgrade Coupled System in High Speed Railway with Pseudoexcitation Method

    Directory of Open Access Journals (Sweden)

    Xinwen Yang

    2016-01-01

    Full Text Available In order to reduce the ground-borne vibration caused by wheel/rail interaction in the ballastless track of high speed railways, viscoelastic asphalt concrete materials are filled between the track and the subgrade to attenuate wheel/rail force. A high speed train-track-subgrade vertical coupled dynamic model is developed in the frequency domain. In this model, coupling effects between the vehicle and the track and between the track and the subgrade are considered. The full vehicle is represented by some rigid body models of one body, two bogies, and four wheelsets connected to each other with springs and dampers. The track and subgrade system is considered as a multilayer beam model in which layers are connected to each other with springs and damping elements. The vertical receptance of the rail is discussed and the receptance contribution of the wheel/rail interaction is investigated. Combined with the pseudoexcitation method, a solution of the random dynamic response is presented. The random vibration responses and transfer characteristics of the ballastless track and subgrade system are obtained under track random irregularity when a high speed vehicle runs through. The influences of asphalt concrete layer’s stiffness and vehicle speed on track and subgrade coupling vibration are analyzed.

  14. Sensor Placement Optimization of Vibration Test on Medium-Speed Mill

    Directory of Open Access Journals (Sweden)

    Lihua Zhu

    2015-01-01

    Full Text Available Condition assessment and decision making are important tasks of vibration test on dynamic machines, and the accuracy of dynamic response can be achieved by the sensors placed on the structure reasonably. The common methods and evaluation criteria of optimal sensor placement (OSP were summarized. In order to test the vibration characteristic of medium-speed mill in the thermal power plants, the optimal placement of 12 candidate measuring points in X, Y, and Z directions on the mill was discussed for different targeted modal shapes, respectively. The OSP of medium-speed mill was conducted using the effective independence method (EfI and QR decomposition algorithm. The results showed that the order of modal shapes had an important influence on the optimization results. The difference of these two methods on the sensor placement optimization became smaller with the decrease of the number of target modes. The final scheme of OSP was determined based on the optimal results and the actual test requirements. The field test results were basically consistent with the finite element analysis results, which indicated the sensor placement optimization for vibration test on the medium-speed mill was feasible.

  15. Sensor design for outdoor racing bicycle field testing for human vibration comfort evaluation

    Science.gov (United States)

    Vanwalleghem, Joachim; De Baere, Ives; Loccufier, Mia; Van Paepegem, Wim

    2013-09-01

    This paper is concerned with the vibrational comfort evaluation of the cyclist when cycling a rough surface. Outdoor comfort tests have so far only been done through instrumenting the bicycle with accelerometers. This work instruments a racing bicycle with custom-made contact force sensors and velocity sensors to acquire human comfort through the absorbed power method. Comfort evaluation is assessed at the hand-arm and seat interface of the cyclist with the bicycle. By means of careful finite-element analysis for designing the force gauges at the handlebar and the seat combined with precise calibration of both force and velocity sensors, all sensors have proven to work properly. Initial field tests are focused on the proper functioning of the designed sensors and their suitability for vibration comfort measurements. Tests on a cobblestone road reveal that the outcome of the absorbed power values is within the same range as those from laboratory tests found in the literature. This sensor design approach for outdoor testing with racing bicycles may give a new interpretation on evaluating the cyclist's comfort since the vibrational load is not only quantified in terms of acceleration but also in terms of force and velocity at the bicycle-cyclist contact points.

  16. Vibration and thermal vacuum qualification test results for a low-voltage tungsten-halogen light

    Science.gov (United States)

    Sexton, J. Andrew

    1991-01-01

    The results of a space flight qualification test program for a low-voltage, quartz tungsten-halogen light are presented. The test program was designed to qualify a halogen light for use in the Pool Boiling Experiment, a Get Away Special (GAS) payload that will be flown in the space shuttle payload bay. Vibration and thermal vacuum tests were performed. The test results indicated that the halogen light will survive the launch and ascent loads, and that the convection-free environment associated with the GAS payload system will not detrimentally affect the operation of the halogen light.

  17. Accelerated Vibration Test of coolant channel components under simulated flow induced excitation

    Energy Technology Data Exchange (ETDEWEB)

    Meher, K.K., E-mail: kkmeher@barc.gov.in; Pandey, J.K., E-mail: jkpandey@barc.gov.in; RamaRao, A., E-mail: arr@barc.gov.in

    2016-04-15

    Highlights: • The present study deals with the issue of loosening of the nut in the Grayloc joint due to flow induced vibration and fret in the feeder pipes in contact due to differential creep in the neighbouring channels. • Accelerated test has been done on the Grayloc joint on simulated flow induced vibration to study the effect of loosening of the nut. • In the present accelerated test, the component has not been led to failure (loosening) and an estimation of its service life has been approached based on the severity of test. • The inverse square law approach based on PSD comparison for severity of test have been used to correlate the actual operational hours and the Laboratory test hours to verify the loosening of the Grayloc nut for the present study. • By inverse power law approach, the minimum number of reactor-hours equivalent to 80 h of testing is 46,080 h (5.26 full power years). - Abstract: The present study outlines the accelerated testing procedure of a Grayloc joint assembly for possible loosening of its nut due to flow induced vibration. The concern of the Grayloc nut getting loosened in the absence of a lock nut due to flow induced vibration and the resulting fretting in the feeder pipes in contact due to differential creep in the neighbouring channels has been addressed here. The severity of the test was decided based on actual site measurement under different operating flow conditions and comparison of power spectral density (PSD). The laboratory test results were extrapolated for estimation of life of the component under operating condition using inverse power law approach. The uniqueness of the accelerated test is that the component under test has not been led to failure for assessing its operating life unlike conventional accelerated testing. From the tests and analysis, it was deduced that 80 h of accelerated laboratory testing was equivalent to 5.26 full power years (46,080 h) of the reactor operating life. The test duration was

  18. Improved orthogonality check for measured modes. [from ground vibration testing of structures

    Science.gov (United States)

    Berman, A.

    1980-01-01

    A method is proposed for performing an orthogonality check for normal modes derived from ground vibration testing. The method utilizes partitioned mass and stiffness matrices for a linear undamped representation of a structure. The normalization of the modes by the proposed method inherently includes the effects of significant displacements which were not measured; and the method may allow the use of fewer measurement points than would be necessary with the conventional method.

  19. The Shock Vibration Bulletin. Part 4. Structural Dynamics and Modal Test and Analysis

    Science.gov (United States)

    1987-01-01

    Feb. 1971. 17 16. B. Bresler, and A. C. Scordelis , ’Shear Strength of Reinforced Concrete Beams-,Series 100, Issue 13, Structure and Material Research...their adequacy. Dynamic analyses, choice of failure thresholds of failure are even harder to theories , and an accurate dynamic model are estimate...without experimental evidence. shown to be crucial in fulfilling the 29 71 L requirements. Vibration testing data are theories of failure have to be

  20. Force Limited Vibration Testing and Subsequent Redesign of the Naval Postgraduate School CubeSat Launcher

    Science.gov (United States)

    2014-06-01

    complex (e.g., Honeycomb ), this approach can significantly increase the cost of a satellite program. 3. Limit the responses of the satellite to match...LEFT BLANK xv LIST OF ACRONYMS AND ABBREVIATIONS ABC Aft Bulkhead Carrier ADaMSat AS&T Development and Maturation Satellite AFSPC Air Force Space...vibration testing FRF frequency response function GEMSat Government Experimental Multi- Satellite GRACE Government Rideshare Advanced Concepts Experiments

  1. Demonstrating the Effect of Particle Impact Dampers on the Random Vibration Response and Fatigue Life of Printed Wiring Assemblies

    Science.gov (United States)

    Knight, Brent; Montgomery, Randall; Geist, David; Hunt, Ron; LaVerde, Bruce; Towner, Robert

    2013-01-01

    In a recent experimental study, small Particle Impact Dampers (PID) were bonded directly to the surface of printed circuit board (PCB) or printed wiring assemblies (PWA), reducing the random vibration response and increasing the fatigue life. This study provides data verifying practicality of this approach. The measured peak strain and acceleration response of the fundamental out of plane bending mode was significantly attenuated by adding a PID device. Attenuation of this mode is most relevant to the fatigue life of a PWA because the local relative displacements between the board and the supported components, which ultimately cause fatigue failures of the electrical leads of the board-mounted components are dominated by this mode. Applying PID damping at the board-level of assembly provides mitigation with a very small mass impact, especially as compared to isolation at an avionics box or shelf level of assembly. When compared with other mitigation techniques at the PWA level (board thickness, stiffeners, constrained layer damping), a compact PID device has the additional advantage of not needing to be an integral part of the design. A PID can simply be bonded to heritage or commercial off the shelf (COTS) hardware to facilitate its use in environments beyond which it was originally qualified. Finite element analysis and test results show that the beneficial effect is not localized and that the attenuation is not due to the simple addition of mass. No significant, detrimental reduction in frequency was observed. Side-by-side life testing of damped and un-damped boards at two different thicknesses (0.070" and 0.090") has shown that the addition of a PID was much more significant to the fatigue life than increasing the thickness. High speed video, accelerometer, and strain measurements have been collected to correlate with analytical results.

  2. Vibration Durability Testing of Nickel Cobalt Aluminum Oxide (NCA Lithium-Ion 18650 Battery Cells

    Directory of Open Access Journals (Sweden)

    James Michael Hooper

    2016-04-01

    Full Text Available This paper outlines a study undertaken to determine if the electrical performance of Nickel Cobalt Aluminum Oxide (NCA 3.1 Ah 18650 battery cells can be degraded by road induced vibration typical of an electric vehicle (EV application. This study investigates if a particular cell orientation within the battery assembly can result in different levels of cell degradation. The 18650 cells were evaluated in accordance with Society of Automotive Engineers (SAE J2380 standard. This vibration test is synthesized to represent 100,000 miles of North American customer operation at the 90th percentile. This study identified that both the electrical performance and the mechanical properties of the NCA lithium-ion cells were relatively unaffected when exposed to vibration energy that is commensurate with a typical vehicle life. Minor changes observed in the cell’s electrical characteristics were deemed not to be statistically significant and more likely attributable to laboratory conditions during cell testing and storage. The same conclusion was found, irrespective of cell orientation during the test.

  3. A 5-week whole body vibration training improves peak torque performance but has no effect on stretch reflex in healthy adults: a randomized controlled trial.

    Science.gov (United States)

    Yeung, S S; Yeung, E W

    2015-05-01

    This study aimed to investigate the neuromuscular adaptation following a 5-week high frequency and low amplitude whole body vibration (WBV) exercise training. The study is a prospective, double blind, randomized controlled intervention design with a total of 19 subjects volunteered to participate in the study. They were randomly assigned either to WBV exercise training or control group. Both groups participated in a 5-week training program. The intervention group received WBV in semi-squat position on a device with an amplitude of 0.76 mm, frequency of 40Hz, and peak acceleration of 23.9 m/s2. Each vibration training session consisted of 6 series of 60s on with 30s rest period in between. The control group underwent the same statically mini-squatting position without exposure to WBV. The effectiveness of the vibration program was evaluated by vertical jump test and the isokinetic knee extensor peak torque. The possible neural factors that contributed to the improved muscular performance were evaluated by the stretch induced knee jerk reflex. WBV training significantly enhanced the isokinetic knee extensor peak torque performance. Two-way mixed repeated measures analysis of variance revealed significant time effect of the changes in the peak torque (P=0.043) and the effect was significantly different between the intervention and control group (P=0.042). WBV did not affect vertical jump height, reflex latency of VL, EMGVL, and knee jerk angle. The results of this study do not support the hypothesis that the improvement in the muscular performance when subjects exposed to WBV training is attributed by neuromuscular efficiency via modulation of the muscle spindle sensitivity.

  4. A procedure obtaining stiffnesses and masses of a structure from vibration modes and substructure static test data

    Science.gov (United States)

    Edighoffer, H. H.

    1979-01-01

    A component mode desynthesis procedure is developed for determining the unknown vibration characteristics of a structural component (i.e., a launch vehicle) given the vibration characteristics of a structural system composed of that component combined with a known one (i.e., a payload). At least one component static test has to be performed. These data are used in conjunction with the system measured frequencies and mode shapes to obtain the vibration characteristics of each component. The flight dynamics of an empty launch vehicle can be determined from measurements made on a vehicle/payload combination in conjunction with a static test on the payload.

  5. Statistical correlation analysis for comparing vibration data from test and analysis

    Science.gov (United States)

    Butler, T. G.; Strang, R. F.; Purves, L. R.; Hershfeld, D. J.

    1986-01-01

    A theory was developed to compare vibration modes obtained by NASTRAN analysis with those obtained experimentally. Because many more analytical modes can be obtained than experimental modes, the analytical set was treated as expansion functions for putting both sources in comparative form. The dimensional symmetry was developed for three general cases: nonsymmetric whole model compared with a nonsymmetric whole structural test, symmetric analytical portion compared with a symmetric experimental portion, and analytical symmetric portion with a whole experimental test. The theory was coded and a statistical correlation program was installed as a utility. The theory is established with small classical structures.

  6. Serological tests for diagnosis and staging of hand-arm vibration syndrome (HAVS).

    Science.gov (United States)

    Kao, Dennis S; Yan, Ji-Geng; Zhang, Lin-Ling; Kaplan, Rachel E; Riley, Danny A; Matloub, Hani S

    2008-06-01

    The current gold standard for the diagnosis and staging of hand-arm vibration syndrome (HAVS) is the Stockholm workshop scale, which is subjective and relies on the patient's recalling ability and honesty. Therefore, great potentials exist for diagnostic and staging errors. The purpose of this study is to determine if objective serum tests, such as levels of soluble thrombomodulin (sTM) and soluble intercellular adhesion molecule-1 (sICAM-1), may be used in the diagnosis and staging of HAVS. Twenty two nonsmokers were divided into a control group (n = 11) and a vibration group (n = 11). The control group included subjects without history of frequent vibrating tool use. The vibration group included construction workers with average vibrating tool use of 12.2 years. All were classified according to the Stockholm workshop scale (SN, sensorineural symptoms; V, vascular symptoms. SN0, no numbness; SN1, intermittent numbness; SN2, reduced sensory perception; SN3, reduced tactile discrimination; V0, no vasospasmic attacks; V1, intermittent vasospasm involving distal phalanges; V2, intermittent vasospasm extending to middle phalanges; V3, intermittent vasospasm extending to proximal phalanges; V4, skin atrophy/necrosis). All control subjects were SN0 V0. Seven out of 11 vibration subjects were SN1 V1, and 4 out of 11 were SN1 V2. A 10-cm(3) sample of venous blood was collected from each subject. The sTM and sICAM-1 levels were determined by enzyme-linked immunosorbent assay. The mean plasma sTM levels were as follows: control group = 2.93 +/- 0.47 ng/ml, and vibration group = 3.61 +/- 0.24 ng/ml. The mean plasma sICAM-1 levels were as follows: control group = 218.8 +/- 54.1 ng/ml, and vibration group = 300.3 +/- 53.2 ng/ml. The sTM and sICAM-1 differences between control and vibration groups were statistically significant (p Stockholm workshop scale, mean plasma sTM levels were SN0 V0 group = 2.93 +/- 0.47 ng/ml, SN1 V1 group = 3.59 +/- 0.25 ng/ml, and SN1 V2 group = 3

  7. Whole Body Vibration Exercise Protocol versus a Standard Exercise Protocol after ACL Reconstruction: A Clinical Randomized Controlled Trial with Short Term Follow-Up.

    Science.gov (United States)

    Berschin, Gereon; Sommer, Björn; Behrens, Antje; Sommer, Hans-Martin

    2014-09-01

    The suitability and effectiveness of whole body vibration (WBV) exercise in rehabilitation after injury of the anterior cruciate ligament (ACL) was studied using a specially designed WBV protocol. We wanted to test the hypothesis if WBV leads to superior short term results regarding neuromuscular performance (strength and coordination) and would be less time consuming than a current standard muscle strengthening protocol. In this prospective randomized controlled clinical trial, forty patients who tore their ACL and underwent subsequent ligament reconstruction were enrolled. Patients were randomized to the whole body vibration (n=20) or standard rehabilitation exercise protocol (n=20). Both protocols started in the 2(nd) week after surgery. Isometric and isokinetic strength measurements, clinical assessment, Lysholm score, neuromuscular performance were conducted weeks 2, 5, 8 and 11 after surgery. Time spent for rehabilitation exercise was reduced to less than a half in the WBV group. There were no statistically significant differences in terms of clinical assessment, Lysholm score, isokinetic and isometric strength. The WBV group displayed significant better results in the stability test. In conclusion, preliminary data indicate that our whole body vibration muscle exercise protocol seems to be a good alternative to a standard exercise program in ACL-rehabilitation. Despite of its significant reduced time requirement it is at least equally effective compared to a standard rehabilitation protocol. Key pointsIn this prospective randomized controlled clinical trial, we tested the hypothesis if WBV leads to superior short term results regarding neuromuscular performance (strength and coordination) and would be less time consuming than a current standard muscle strengthening protocol in forty patients who underwent ACL reconstruction.Time spent for rehabilitation exercise was reduced to less than a half in the WBV group as compared to the standard exercise group. Both

  8. Numerical Simulation of Vertical Random Vibration of Train-Slab Track-Bridge Interaction System by PEM

    OpenAIRE

    Zhi-ping Zeng; Zhi-wu Yu; Yan-gang Zhao; Wen-tao Xu; Ling-kun Chen; Ping Lou

    2014-01-01

    The paper describes the numerical simulation of the vertical random vibration of train-slab track-bridge interaction system by means of finite element method and pseudoexcitation method. Each vehicle is modeled as four-wheelset mass-spring-damper system with two-layer suspension systems. The rail, slab, and bridge girder are modeled by three-layer elastic Bernoulli-Euler beams connected with each other by spring and damper elements. The equations of motion for the entire system are derived ac...

  9. The Health Monitoring Method of Concrete Dams Based on Ambient Vibration Testing and Kernel Principle Analysis

    Directory of Open Access Journals (Sweden)

    Lin Cheng

    2015-01-01

    Full Text Available The ambient vibration testing (AVT measurement of concrete dams on full-scale can show the practical dynamic properties of structure in the operation state. For most current researches, the AVT data is generally analyzed to identify the structural vibration characteristics, that is, modal parameters. The identified modal parameters, which can provide the global damage information or the damage location information of structure, can be used as the basis of structure health monitoring. Therefore, in this paper, the health monitoring method of concrete dams based on the AVT is studied. The kernel principle analysis (KPCA based method is adopted to eliminate the effect of environmental variables and monitor the health of dam under varying environments. By taking full advantage of the AVT data obtained from vibration observation system of dam, the identification capabilities and the warning capabilities of structural damage can be improved. With the simulated AVT data of the numerical model of a concrete gravity dam and the measured AVT data of a practical engineering, the performance of the dam health monitoring method proposed in this paper is verified.

  10. Fatigue damage from random vibration pulse process of tubular structural elements subject to wind

    DEFF Research Database (Denmark)

    Christensen, Claus F.; Ditlevsen, Ove Dalager

    1997-01-01

    In a wide range of the Reynolds number an elastically suspended circular cylinder surrounded by a homogeneous wind velocity field will generate vortex shedding of a frequency that by and large is proportional to the far field wind velocity. However, if the cylinder is free to vibrate, resonance w...

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

    Science.gov (United States)

    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.

  12. AVM branch vibration test equipment; Moyens d`essais vibratoires au sein du departement AMV

    Energy Technology Data Exchange (ETDEWEB)

    Anne, J.P.

    1995-12-31

    An inventory of the test equipment of the AVM Branch ``Acoustic and Vibratory Mechanics Analysis Methods`` group has been undertaken. The purpose of this inventory is to enable better acquaintance with the technical characteristics of the equipment, providing an accurate definition of their functionalities, ad to inform potential users of the possibilities and equipment available in this field. The report first summarizes the various experimental surveys conduced. Then, using the AVM equipment database to draw up an exhaustive list of available equipment, it provides a full-scope picture of the vibration measurement systems (sensors, conditioners and exciters) and data processing resources commonly used on industrial sites and in laboratories. A definition is also given of a mobile test unit, called `shelter`, and a test bench used for the testing and performance rating of the experimental analysis methods developed by the group. The report concludes with a description of two fixed installations: - the calibration bench ensuring the requisite quality level for the vibration measurement systems ; - the training bench, whereby know-how acquired in the field in the field of measurement and experimental analysis processes is made available to others. (author). 27 refs., 15 figs., 2 appends.

  13. Effect of voluntary periodic muscular activity on nonlinearity in the apparent mass of the seated human body during vertical random whole-body vibration

    Science.gov (United States)

    Huang, Ya; Griffin, Michael J.

    2006-12-01

    The principal resonance frequency in the driving-point impedance of the human body decreases with increasing vibration magnitude—a nonlinear response. An understanding of the nonlinearities may advance understanding of the mechanisms controlling body movement and improve anthropodynamic modelling of responses to vibration at various magnitudes. This study investigated the effects of vibration magnitude and voluntary periodic muscle activity on the apparent mass resonance frequency using vertical random vibration in the frequency range 0.5-20 Hz. Each of 14 subjects was exposed to 14 combinations of two vibration magnitudes (0.25 and 2.0 m s -2 root-mean square (rms)) in seven sitting conditions: two without voluntary periodic movement (A: upright; B: upper-body tensed), and five with voluntary periodic movement (C: back-abdomen bending; D: folding-stretching arms from back to front; E: stretching arms from rest to front; F: folding arms from elbow; G: deep breathing). Three conditions with voluntary periodic movement significantly reduced the difference in resonance frequency at the two vibration magnitudes compared with the difference in a static sitting condition. Without voluntary periodic movement (condition A: upright), the median apparent mass resonance frequency was 5.47 Hz at the low vibration magnitude and 4.39 Hz at the high vibration magnitude. With voluntary periodic movement (C: back-abdomen bending), the resonance frequency was 4.69 Hz at the low vibration magnitude and 4.59 Hz at the high vibration magnitude. It is concluded that back muscles, or other muscles or tissues in the upper body, influence biodynamic responses of the human body to vibration and that voluntary muscular activity or involuntary movement of these parts can alter their equivalent stiffness.

  14. A Quickly Tested Pascal Random Number Generator for Microcomputers.

    Science.gov (United States)

    1985-05-01

    in any way at equal intervals spaced h units apart, the serial correlation of the series can be obtained for various lags and tested against...pass handily. The unit range between zero and unity was divided into 100 equally spaced frequencies, and the generated random numbers were...NSDTEST; (*MEAN AND SDEV TESTS*) FREQKOLTEST; (*CHISQ FREQ DISTR AND KOLMOGOROFF -SMIRNOV TESTS*) PAIRTEST; (*TEST DISTR OF RANDOM PAIRS*) TRIOTEST; (*TEST

  15. Development of a sine-dwell ground vibration test (GVT) system

    CSIR Research Space (South Africa)

    Van Zyl, Lourens H

    2006-02-27

    Full Text Available Vibration Test (GVT) System Presented at CSIR Research and Innovation Conference: 27 - 28 February 2006 DPSS Mr Louw van Zyl Mr Erik Wegman 27 February 2006 Slide 2 © CSIR 2006 www.csir.co.za Agenda • Introduction Why ground... stream_source_info VanZyl_2006.pdf.txt stream_content_type text/plain stream_size 9765 Content-Encoding UTF-8 stream_name VanZyl_2006.pdf.txt Content-Type text/plain; charset=UTF-8 Development of a Sine-Dwell Ground...

  16. On testing the missing at random assumption

    DEFF Research Database (Denmark)

    Jaeger, Manfred

    2006-01-01

    Most approaches to learning from incomplete data are based on the assumption that unobserved values are missing at random (mar). While the mar assumption, as such, is not testable, it can become testable in the context of other distributional assumptions, e.g. the naive Bayes assumption. In this ......Most approaches to learning from incomplete data are based on the assumption that unobserved values are missing at random (mar). While the mar assumption, as such, is not testable, it can become testable in the context of other distributional assumptions, e.g. the naive Bayes assumption...

  17. Theoretical and Numerical Experiences on a Test Rig for Active Vibration Control of Mechanical Systems with Moving Constraints

    Directory of Open Access Journals (Sweden)

    M. Rinchi

    2004-01-01

    Full Text Available Active control of vibrations in mechanical systems has recently benefited of the remarkable development of robust control techniques. These control techniques are able to guarantee performances in spite of unavoidable modeling errors. They have been successfully codified and implemented for vibrating structures whose uncertain parameters could be assumed to be time-invariant. Unfortunately a wide class of mechanical systems, such as machine tools with carriage motion realized by a ball-screw, are characterized by time varying modal parameters. The focus of this paper is on modeling and controlling the vibrations of such systems. A test rig for active vibration control is presented. An analytical model of the test rig is synthesized starting by design data. Through experimental modal analysis, parametric identification and updating procedures, the model has been refined and a control system has been synthesized.

  18. Analysis of crack initiation and growth in the high level vibration test at Tadotsu

    Energy Technology Data Exchange (ETDEWEB)

    Kassir, M.K.; Park, Y.J.; Hofmayer, C.H.; Bandyopadhyay, K.K.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States)

    1993-08-01

    The High Level Vibration Test data are used to assess the accuracy and usefulness of current engineering methodologies for predicting crack initiation and growth in a cast stainless steel pipe elbow under complex, large amplitude loading. The data were obtained by testing at room temperature a large scale modified model of one loop of a PWR primary coolant system at the Tadotsu Engineering Laboratory in Japan. Fatigue crack initiation time is reasonably predicted by applying a modified local strain approach (Coffin-Mason-Goodman equation) in conjunction with Miner`s rule of cumulative damage. Three fracture mechanics methodologies are applied to investigate the crack growth behavior observed in the hot leg of the model. These are: the {Delta}K methodology (Paris law), {Delta}J concepts and a recently developed limit load stress-range criterion. The report includes a discussion on the pros and cons of the analysis involved in each of the methods, the role played by the key parameters influencing the formulation and a comparison of the results with the actual crack growth behavior observed in the vibration test program. Some conclusions and recommendations for improvement of the methodologies are also provided.

  19. Localization of simulated damage on a steel beam from random vibrations

    Czech Academy of Sciences Publication Activity Database

    Bayer, Jan; Král, J.; Urushadze, Shota

    2018-01-01

    Roč. 62, č. 1 (2018), s. 112-116 ISSN 0553-6626 R&D Projects: GA ČR(CZ) GC17-26353J Institutional support: RVO:68378297 Keywords : damage localization * change of natural modes * flexibility matrix * flexibility curvatures * case study * damage detection * vibration monitoring Subject RIV: JM - Building Engineering OBOR OECD: Construction engineering, Municipal and structural engineering Impact factor: 0.313, year: 2016 https://pp.bme.hu/ci/ article /view/10625

  20. Vibration Analysis of Randomly Oriented Carbon Nanotube Based on FGM Beam Using Timoshenko Theory

    OpenAIRE

    Mohammad Amin Rashidifar; Darvish Ahmadi

    2015-01-01

    The carbon nanotube (CNT) reinforced functionally graded materials (FGM) are expected to be the new generation materials having wide range of unexplored potential applications in various technological areas such as aerospace and structural and chemical industry. The present work deals with the finite element modeling and free vibration analysis of CNT based functionally graded beam using three-dimensional Timoshenko beam theory. It has been assumed that the material properties of CNT based FG...

  1. Testing techniques and comparisons between theory and test for vibration modes of ring stiffened truncated-cone shells.

    Science.gov (United States)

    Naumann, E. C.

    1972-01-01

    Vibration tests were carried out on truncated-cone shells with widely spaced ring stiffeners. The models were excited by an air shaker for LF modes and by small electrodynamic shakers for HF modes. The Novozhilov thin shell theory according to which a ring is an assembly of an arbitrary number of segments, each being a short truncated-cone shell of uniform thickness, is used in the analysis of the results. A mobile, noncontacting, displacement-sensitive sensor system developed by the author was used in the tests. Tests results are given for a free-free 60-deg cone and for a clamped-free 60-deg cone. The tests are characterized as having considerable value for the classification of prevalent multimode responses in shells of this type.

  2. The Use of Randomization Tests in Single-Subject Research

    Science.gov (United States)

    Haardorfer, Regine; Gagne, Phill

    2010-01-01

    Some researchers have argued for the use of or have attempted to make use of randomization tests in single-subject research. To address this tide of interest, the authors of this article describe randomization tests, discuss the theoretical rationale for applying them to single-subject research, and provide an overview of the methodological…

  3. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain......This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  4. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    1998-01-01

    concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain......This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  5. The Skull Vibration-Induced Nystagmus Test of Vestibular Function—A Review

    Science.gov (United States)

    Dumas, Georges; Curthoys, Ian S.; Lion, Alexis; Perrin, Philippe; Schmerber, Sébastien

    2017-01-01

    A 100-Hz bone-conducted vibration applied to either mastoid induces instantaneously a predominantly horizontal nystagmus, with quick phases beating away from the affected side in patients with a unilateral vestibular loss (UVL). The same stimulus in healthy asymptomatic subjects has little or no effect. This is skull vibration-induced nystagmus (SVIN), and it is a useful, simple, non-invasive, robust indicator of asymmetry of vestibular function and the side of the vestibular loss. The nystagmus is precisely stimulus-locked: it starts with stimulation onset and stops at stimulation offset, with no post-stimulation reversal. It is sustained during long stimulus durations; it is reproducible; it beats in the same direction irrespective of which mastoid is stimulated; it shows little or no habituation; and it is permanent—even well-compensated UVL patients show SVIN. A SVIN is observed under Frenzel goggles or videonystagmoscopy and recorded under videonystagmography in absence of visual-fixation and strong sedative drugs. Stimulus frequency, location, and intensity modify the results, and a large variability in skull morphology between people can modify the stimulus. SVIN to 100 Hz mastoid stimulation is a robust response. We describe the optimum method of stimulation on the basis of the literature data and testing more than 18,500 patients. Recent neural evidence clarifies which vestibular receptors are stimulated, how they cause the nystagmus, and why the same vibration in patients with semicircular canal dehiscence (SCD) causes a nystagmus beating toward the affected ear. This review focuses not only on the optimal parameters of the stimulus and response of UVL and SCD patients but also shows how other vestibular dysfunctions affect SVIN. We conclude that the presence of SVIN is a useful indicator of the asymmetry of vestibular function between the two ears, but in order to identify which is the affected ear, other information and careful clinical judgment are

  6. Monitoring vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Tiryaki, B. [Hacettepe University (Turkey). Dept. of Mining Engineering

    2003-12-01

    The paper examines the prediction and optimisation of machine vibrations in longwall shearers. Underground studies were carried out at the Middle Anatolian Lignite Mine, between 1993 and 1997. Several shearer drums with different pick lacing arrangements were designed and tested on double-ended ranging longwall shearers employed at the mine. A computer program called the Vibration Analysis Program (VAP) was developed for analysing machine vibrations in longwall shearers. Shearer drums that were tested underground, as well as some provided by leading manufacturers, were analyzed using these programs. The results of the experiments and computer analyses are given in the article. 4 refs., 9 figs.

  7. Objectives and Progress on Ground Vibration Testing for the Ares Projects

    Science.gov (United States)

    Tuma, Margaret L.; Chenevert, Donald J.

    2010-01-01

    Integrated vehicle ground vibration testing (IVGVT) will be a vital component for ensuring the safety of NASA s next generation of exploration vehicles to send human beings to the Moon and beyond. A ground vibration test (GVT) measures the fundamental dynamic characteristics of launch vehicles during various phases of flight. The Ares Flight & Integrated Test Office (FITO) will be conducting the IVGVT for the Ares I crew launch vehicle at Marshall Space Flight Center (MSFC) from 2012 to 2014 using Test Stand (TS) 4550. MSFC conducted similar GVT for the Saturn V and Space Shuttle vehicles. FITO will perform the IVGVT on the Ares I crew launch vehicle, which will lift the Orion crew exploration vehicle to low Earth orbit, and the Ares V cargo launch vehicle, which can launch the lunar lander into orbit and send the combined Orion/lander vehicles toward the Moon. Ares V consists of a six-engine core stage with two solid rocket boosters and an Earth departure stage (EDS). The same engine will power the EDS and the Ares I second stage. The current plan is to test six configurations in three unique test positions inside TS 4550. Four Ares I second stage test configurations will be tested in Position 3, consisting of the Upper Stage and Orion crew module in four nominal conditions: J-2X engine ignition, post Launch Abort System (LAS) jettison, critical slosh mass, and J-2X burn-out. Position 2 consists of the entire launch stack at first stage burn-out (using empty first stage segments). Position 1 represents the entire launch stack at lift-off (using inert first stage segments). Because of long disuse, TS 4550 is being repaired and modified for reactivation to conduct the Ares I IVGVT. The Shuttle-era platforms have been removed and are being replaced with mast climbers that provide ready access to the test articles and can be moved easily to support different positions within the test stand. Two new cranes will help move test articles at the test stand and at the

  8. Correlation of analysis with high level vibration test results for primary coolant piping

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.J.; Hofmayer, C.H. [Brookhaven National Lab., Upton, NY (United States); Costello, J.F. [Nuclear Regulatory Commission, Washington, DC (United States)

    1992-05-01

    Dynamic tests on a modified 1/2.5-scale model of pressurized water reactor (PWR) primary coolant piping were performed using a large shaking table at Tadotsu, Japan. The High Level Vibration Test (HLVT) program was part of a cooperative study between the United States (Nuclear Regulatory Commission/Brookhaven National Laboratory, NRC/BNL) and Japan (Ministry of International Trade and Industry/Nuclear Power Engineering Center). During the test program, the excitation level of each test run was gradually increased up to the limit of the shaking table and significant plastic strains, as well as cracking, were induced in the piping. To fully utilize the test results, NRC/BNL sponsored a project to develop corresponding analytical predictions for the nonlinear dynamic response of the piping for selected test runs. The analyses were performed using both simplified and detailed approaches. The simplified approaches utilize a linear solution and an approximate formulation for nonlinear dynamic effects such as the use of a deamplification factor. The detailed analyses were performed using available nonlinear finite element computer codes, including the MARC, ABAQUS, ADINA and WECAN codes. A comparison of various analysis techniques with the test results shows a higher prediction error in the detailed strain values in the overall response values. A summary of the correlation analyses was presented before the BNL. This paper presents a detailed description of the various analysis results and additional comparisons with test results.

  9. Correlation of analysis with high level vibration test results for primary coolant piping

    Energy Technology Data Exchange (ETDEWEB)

    Park, Y.J.; Hofmayer, C.H. (Brookhaven National Lab., Upton, NY (United States)); Costello, J.F. (Nuclear Regulatory Commission, Washington, DC (United States))

    1992-01-01

    Dynamic tests on a modified 1/2.5-scale model of pressurized water reactor (PWR) primary coolant piping were performed using a large shaking table at Tadotsu, Japan. The High Level Vibration Test (HLVT) program was part of a cooperative study between the United States (Nuclear Regulatory Commission/Brookhaven National Laboratory, NRC/BNL) and Japan (Ministry of International Trade and Industry/Nuclear Power Engineering Center). During the test program, the excitation level of each test run was gradually increased up to the limit of the shaking table and significant plastic strains, as well as cracking, were induced in the piping. To fully utilize the test results, NRC/BNL sponsored a project to develop corresponding analytical predictions for the nonlinear dynamic response of the piping for selected test runs. The analyses were performed using both simplified and detailed approaches. The simplified approaches utilize a linear solution and an approximate formulation for nonlinear dynamic effects such as the use of a deamplification factor. The detailed analyses were performed using available nonlinear finite element computer codes, including the MARC, ABAQUS, ADINA and WECAN codes. A comparison of various analysis techniques with the test results shows a higher prediction error in the detailed strain values in the overall response values. A summary of the correlation analyses was presented before the BNL. This paper presents a detailed description of the various analysis results and additional comparisons with test results.

  10. Design, analysis and testing of a new piezoelectric tool actuator for elliptical vibration turning

    Science.gov (United States)

    Lin, Jieqiong; Han, Jinguo; Lu, Mingming; Yu, Baojun; Gu, Yan

    2017-08-01

    A new piezoelectric tool actuator (PETA) for elliptical vibration turning has been developed based on a hybrid flexure hinge connection. Two double parallel four-bar linkage mechanisms and two right circular flexure hinges were chosen to guide the motion. The two input displacement directional stiffness were modeled according to the principle of virtual work modeling method and the kinematic analysis was conducted theoretically. Finite element analysis was used to carry out static and dynamic analyses. To evaluate the performance of the developed PETA, off-line experimental tests were carried out to investigate the step responses, motion strokes, resolutions, parasitic motions, and natural frequencies of the PETA along the two input directions. The relationship between input displacement and output displacement, as well as the tool tip’s elliptical trajectory in different phase shifts was analyzed. By using the developed PETA mechanism, micro-dimple patterns were generated as the preliminary application to demonstrate the feasibility and efficiency of PETA for elliptical vibration turning.

  11. A randomized pilot study of stochastic vibration therapy in spinocerebellar ataxia.

    Science.gov (United States)

    Kaut, O; Jacobi, H; Coch, C; Prochnicki, A; Minnerop, M; Klockgether, T; Wüllner, U

    2014-04-01

    Whole body vibration (WBV) is a biomechanical treatment used widely in professional sports and rehabilitation. We examined the effect of stochastic WBV on ataxia in spinocerebellar ataxia types 1, 2, 3, and 6 (SCA 1, 2, 3 and 6) in a single-center double-blind sham-controlled study. Stochastic WBV was applied on four sequent days, each treatment consisting of five stimulus trains of 60-s duration at a frequency of 6.5 Hz and 60-s resting time between stimuli (n = 17). Patients allocated to the sham group received the same treatment with 1 Hz (n = 15). All patients were rated at baseline and after the last treatment using clinical scores (SARA, SCAFI, and INAS). After treatment, we found significant improvements of gait, posture, and speed of speech in the verum group while limb kinetics and ataxia of speech did not respond. Stochastic WBV might act on proprioceptive mechanisms and could also stimulate non-cerebellar/compensatory mechanisms. But at present, the involved cellular mechanism and the presumed neuronal loops cannot be deciphered. Thus, future work is needed to understand the mechanisms of whole body vibration. Finally, the use of stochastic WBV could provide a supplementation to treat ataxia in SCA and can be combined with physiotherapeutical motor training.

  12. The effects of whole-body vibration on the Wingate test for anaerobic power when applying individualized frequencies.

    Science.gov (United States)

    Surowiec, Rachel K; Wang, Henry; Nagelkirk, Paul R; Frame, Jeffrey W; Dickin, D Clark

    2014-07-01

    Recently, individualized frequency (I-Freq) has been introduced with the notion that athletes may elicit a greater reflex response at differing levels (Hz) of vibration. The aim of the study was to evaluate acute whole-body vibration as a feasible intervention to increase power in trained cyclists and evaluate the efficacy of using I-Freq as an alternative to 30Hz, a common frequency seen in the literature. Twelve highly trained, competitive male cyclists (age, 29.9 ± 10.0 years; body height, 175.4 ± 7.8 cm; body mass, 77.3 ± 13.9 kg) participated in the study. A Wingate test for anaerobic power was administered on 3 occasions: following a control of no vibration, 30 Hz, or I-freq. Measures of peak power, average power (AP), and the rate of fatigue were recorded and compared with the vibration conditions using separate repeated measures analysis of variance. Peak power, AP, and the rate of fatigue were not significantly impacted by either the 30 Hz or I-Freq vibration interventions (p > 0.05). Given the trained status of the individuals in this study, the ability to elicit an acute response may have been muted. Future studies should further refine the vibration parameters used and assess changes in untrained or recreationally trained populations.

  13. 75 FR 79308 - Alcohol and Drug Testing: Determination of Minimum Random Testing Rates for 2011

    Science.gov (United States)

    2010-12-20

    ... Federal Railroad Administration 49 CFR Part 219 Alcohol and Drug Testing: Determination of Minimum Random... rail industry random testing positive rates were .037 percent for drugs and .014 percent for alcohol... 25 percent of covered railroad employees. In addition, because the industry-wide random alcohol...

  14. Vertical vibrations of composite bridge/track structure/high-speed train systems. Part 3: Deterministic and random vibrations of exemplary system

    National Research Council Canada - National Science Library

    M. Podworna; M. Klasztorny

    2014-01-01

    ...) bridge/track structure/high-speed train system (BTT), developed in Part 2, advanced computer algorithms for the BTT numerical modelling and simulation as well as a computer programme to simulate vertical vibrations of BTT systems are developed...

  15. Study protocol: the effect of whole body vibration on acute unilateral unstable lateral ankle sprain- a biphasic randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Baumbach Sebastian Felix

    2013-01-01

    Full Text Available Abstract Background Ankle sprains often result in ankle instability, which is most likely caused by damage to passive structures and neuromuscular impairment. Whole body vibration (WBV is a neuromuscular training method improving those impaired neurologic parameters. The aim of this study is to compare the current gold standard functional treatment to functional treatment plus WBV in patients with acute unilateral unstable inversion ankle sprains. Methods/Design 60 patients, aged 18–40 years, presenting with an isolated, unilateral, acute unstable inversion ankle sprain will be included in this bicentric, biphasic, randomized controlled trial. Samples will be randomized by envelope drawing. All patients will be allowed early mobilization and pain-dependent weight bearing, limited functional immobilization by orthosis, PRICE, NSARDs as well as home and supervised physiotherapy. Supervised physical therapy will take place twice a week, for 30 minutes for a period of 6 weeks, following a standardized intervention protocol. During supervised physical therapy, the intervention group will perform exercises similar to those of the control group, on a side-alternating sinusoidal vibration platform. Two time-dependent primary outcome parameters will be assessed: short-term outcome after six weeks will be postural control quantified by the sway index; mid-term outcome after one year will be assessed by subjective instability, defined by the presence of giving-way attacks. Secondary outcome parameters include: return to pre-injury level of activities, residual pain, recurrence, objective instability, energy/coordination, Foot and Ankle Disability Index and EQ 5D. Discussion This is the first trial investigating the effects of WBV in patients with acute soft tissue injury. Inversion ankle sprains often result in ankle instability, which is most likely due to damage of neurological structures. Due to its unique, frequency dependent, influence on various

  16. Integrated Vehicle Ground Vibration Testing in Support of NASA Launch Vehicle Loads and Controls Analysis

    Science.gov (United States)

    Tuma, Margaret L.; Davis, Susan R.; Askins, Bruce R.; Salyer, Blaine H.

    2008-01-01

    The National Aeronautics and Space Administration (NASA) Ares Projects Office (APO) is continuing to make progress toward the final design of the Ares I crew launch vehicle and Ares V cargo launch vehicle. Ares I and V will form the space launch capabilities necessary to fulfill NASA's exploration strategy of sending human beings to the Moon, Mars, and beyond. As with all new space vehicles there will be a number of tests to ensure the design can be Human Rated. One of these is the Integrated Vehicle Ground Vibration Test (IVGVT) that will be measuring responses of the Ares I as a system. All structural systems possess a basic set of physical characteristics unique to that system. These unique characteristics include items such as mass distribution, frequency and damping. When specified, they allow engineers to understand and predict how a structural system like the Ares I launch vehicle behaves under given loading conditions. These physical properties of launch vehicles may be predicted by analysis or measured through certain types of tests. Generally, these properties are predicted by analysis during the design phase of a launch vehicle and then verified through testing before the vehicle is Human Rated. The IVGVT is intended to measure by test the fundamental dynamic characteristics of Ares I during various phases of operational/flight. This testing includes excitations of the vehicle in lateral, longitudinal, and torsional directions at vehicle configurations representing different trajectory points. During the series of tests, properties such as natural frequencies, mode shapes, and transfer functions are measured directly. These data will then be used to calibrate loads and Guidance, Navigation, and Controls (GN&C) analysis models for verifying analyses of Ares I. NASA launch vehicles from Saturn to Shuttle have undergone Ground Vibration Tests (GVTs) leading to successful launch vehicles. A GVT was not performed on the unmanned Delta III. This vehicle was

  17. Random vibration analysis of train-bridge under track irregularities and traveling seismic waves using train-slab track-bridge interaction model

    Science.gov (United States)

    Zeng, Zhi-Ping; Zhao, Yan-Gang; Xu, Wen-Tao; Yu, Zhi-Wu; Chen, Ling-Kun; Lou, Ping

    2015-04-01

    The frequent use of bridges in high-speed railway lines greatly increases the probability that trains are running on bridges when earthquakes occur. This paper investigates the random vibrations of a high-speed train traversing a slab track on a continuous girder bridge subjected to track irregularities and traveling seismic waves by the pseudo-excitation method (PEM). To derive the equations of motion of the train-slab track-bridge interaction system, the multibody dynamics and finite element method models are used for the train and the track and bridge, respectively. By assuming track irregularities to be fully coherent random excitations with time lags between different wheels and seismic accelerations to be uniformly modulated, non-stationary random excitations with time lags between different foundations, the random load vectors of the equations of motion are transformed into a series of deterministic pseudo-excitations based on PEM and the wheel-rail contact relationship. A computer code is developed to obtain the time-dependent random responses of the entire system. As a case study, the random vibration characteristics of an ICE-3 high-speed train traversing a seven-span continuous girder bridge simultaneously excited by track irregularities and traveling seismic waves are analyzed. The influence of train speed and seismic wave propagation velocity on the random vibration characteristics of the bridge and train are discussed.

  18. Force Limiting Vibration Tests Evaluated from both Ground Acoustic Tests and FEM Simulations of a Flight Like Vehicle System Assembly

    Science.gov (United States)

    Smith, Andrew; LaVerde, Bruce; Waldon, James; Hunt, Ron

    2014-01-01

    Marshall Space Flight Center has conducted a series of ground acoustic tests with the dual goals of informing analytical judgment, and validating analytical methods when estimating vibroacoustic responses of launch vehicle subsystems. The process of repeatedly correlating finite element-simulated responses with test-measured responses has assisted in the development of best practices for modeling and post-processing. In recent work, force transducers were integrated to measure interface forces at the base of avionics box equipment. Other force data was indirectly measured using strain gauges. The combination of these direct and indirect force measurements has been used to support and illustrate the advantages of implementing the Force Limiting approach for equipment qualification tests. The comparison of force response from integrated system level tests to measurements at the same locations during component level vibration tests provides an excellent illustration. A second comparison of the measured response cases from the system level acoustic tests to finite element simulations has also produced some principles for assessing the suitability of Finite Element Models (FEMs) for making vibroacoustics estimates. The results indicate that when FEM models are employed to guide force limiting choices, they should include sufficient detail to represent the apparent mass of the system in the frequency range of interest.

  19. The relationship between clinical and standardized tests for hand-arm vibration syndrome.

    Science.gov (United States)

    Poole, C J M; Mason, H; Harding, A-H

    2016-06-01

    Standardized laboratory tests are undertaken to assist the diagnosis and staging of hand-arm vibration syndrome (HAVS), but the strength of the relationship between the tests and clinical stages of HAVS is unknown. To assess the relationship between the results of thermal aesthesiometry (TA), vibrotactile (VT) thresholds and cold provocation (CP) tests with the modified Stockholm scales for HAVS and to determine whether the relationship is affected by finger skin temperature. Consecutive records of workers referred to a Tier 5 HAVS assessment centre from 2006 to 2015 were identified. The diagnosis and staging of cases was undertaken from the clinical information contained in the records. Cases with alternative or mixed diagnoses were excluded and staging performed according to the modified Stockholm scale without knowledge of the results of the standardized laboratory tests. A total of 279 cases of HAVS were analysed. Although there was a significant trend for sensorineural (SN) and vascular scores to increase with clinical stage (P 30°C. CP scores distributed bimodally and correlated poorly with clinical staging (r = 0.2). Standardized SN tests distinguish between the lower Stockholm stages, but not above 2SN early. This has implications for health surveillance and UK policy. © Crown copyright 2016.

  20. Active vibration control testing of the SPICES program: final demonstration article

    Science.gov (United States)

    Dunne, James P.; Jacobs, Jack H.

    1996-05-01

    The Synthesis and Processing of Intelligent Cost Effective Structures (SPICES) Program is a partnership program sponsored by the Advanced Research Projects Agency. The mission of the program is to develop cost effective material processing and synthesis technologies to enable new products employing active vibration suppression and control devices to be brought to market. The two year program came to fruition in 1995 through the fabrication of the final smart components and testing of an active plate combined with two trapezoidal rails, forming an active mount. Testing of the SPICES combined active mount took place at McDonnell Douglas facilities in St. Louis, MO, in October-December 1995. Approximately 15 dB reduction in overall response of a motor mounted on the active structure was achieved. Further details and results of the SPICES combined active mount demonstration testing are outlined. Results of numerous damping and control strategies that were developed and employed in the testing are presented, as well as aspects of the design and fabrication of the SPICES active mount components.

  1. Ensuring Safe Exploration: Ares Launch Vehicle Integrated Vehicle Ground Vibration Testing

    Science.gov (United States)

    Tuma, M. L.; Chenevert, D. J.

    2010-01-01

    Integrated vehicle ground vibration testing (IVGVT) will be a vital component for ensuring the safety of NASA's next generation of exploration vehicles to send human beings to the Moon and beyond. A ground vibration test (GVT) measures the fundamental dynamic characteristics of launch vehicles during various phases of flight. The Ares Flight & Integrated Test Office (FITO) will be leading the IVGVT for the Ares I crew launch vehicle at Marshall Space Flight Center (MSFC) from 2012 to 2014 using Test Stand (TS) 4550. MSFC conducted similar GVT for the Saturn V and Space Shuttle vehicles. FITO is responsible for performing the IVGVT on the Ares I crew launch vehicle, which will lift the Orion crew exploration vehicle to low Earth orbit, and the Ares V cargo launch vehicle, which can launch the lunar lander into orbit and send the combined Orionilander vehicles toward the Moon. Ares V consists of a six-engine core stage with two solid rocket boosters and an Earth departure stage (EDS). The same engine will power the EDS and the Ares I second stage. For the Ares IVGVT, the current plan is to test six configurations in three unique test positions inside TS 4550. Position 1 represents the entire launch stack at liftoff (using inert first stage segments). Position 2 consists of the entire launch stack at first stage burn-out (using empty first stage segments). Four Ares I second stage test configurations will be tested in Position 3, consisting of the Upper Stage and Orion crew module in four nominal conditions: J-2X engine ignition, post Launch Abort System (LAS) jettison, critical slosh mass, and J-2X burn-out. Because of long disuse, TS 4550 is being repaired and reactivated to conduct the Ares I IVGVT. The Shuttle-era platforms have been removed and are being replaced with mast climbers that provide ready access to the test articles and can be moved easily to support different positions within the test stand. The electrical power distribution system for TS 4550 was

  2. Immediate Effects of External Vibration vs Placebo on Vocal Function Therapy in Singers: A Randomized Clinical Trial.

    Science.gov (United States)

    Anderson, Jennifer; DeLuca, Marta; Haines, Mary-Enid; Merrick, Gwen

    2018-01-04

    External vibration therapy (EVT) has been widely used in chronic pain conditions, musculoskeletal rehabilitation, and athletic training. Vibration therapy has been suggested to enhance vocal performance and has been popularized in social media. However, there is no evidence to support its effect on vocal function. To evaluate the immediate effects of EVT in trained singers using acoustic and self-assessment parameters. Prospective, randomized, placebo-controlled interventional study at St Michael's Hospital Voice Clinic, affiliated with the University of Toronto. Data collection and analysis were performed by investigators who were blinded to the group assignment of the participants. Study participants were randomized to EVT or a placebo (control) group. The study dates were September 2015 to December 2016. Participants attended the voice laboratory at St Michael's Hospital, where a standardized data collection protocol was performed, including acoustic parameters, voice range profile, and soft voice tasks, followed by subjective rating of vocal effort or discomfort. The EVT group underwent EVT to 5 neck sites bilaterally. The placebo group underwent the same protocol with a modified device. After the intervention, the participants repeated the standardized data collection. The primary outcome in this study was acoustic analysis (jitter, shimmer, and pitch range) compared before and after treatment. In addition, secondary outcomes included perceived effort or discomfort evaluated by participants after 4 voice tasks proposed to investigate more subtle voice properties. Within and between groups, data sets were statistically analyzed for potential treatment effect. Among 27 participants (age range, 18-50 years; all female), 14 were randomized to the intervention group and 13 to the placebo group. Comparison of the treatment effect on the vowel token acoustic parameters evaluated showed that, after EVT, participants had a more cohesive change with a restricted 95% CI

  3. Small-scale rotor test rig capabilities for testing vibration alleviation algorithms

    Science.gov (United States)

    Jacklin, Stephen A.; Leyland, Jane Anne

    1987-01-01

    A test was conducted to assess the capabilities of a small scale rotor test rig for implementing higher harmonic control and stability augmentation algorithms. The test rig uses three high speed actuators to excite the swashplate over a range of frequencies. The actuator position signals were monitored to measure the response amplitudes at several frequencies. The ratio of response amplitude to excitation amplitude was plotted as a function of frequency. In addition to actuator performance, acceleration from six accelerometers placed on the test rig was monitored to determine whether a linear relationship exists between the harmonics of N/Rev control input and the least square error (LSE) identification technique was used to identify local and global transfer matrices for two rotor speeds at two batch sizes each. It was determined that the multicyclic control computer system interfaced very well with the rotor system and kept track of the input accelerometer signals and their phase angles. However, the current high speed actuators were found to be incapable of providing sufficient control authority at the higher excitation frequencies.

  4. Vortex-Induced Vibration Tests of a Marine Growth Wrapped Cylinder at Subcritical Reynolds Number

    Directory of Open Access Journals (Sweden)

    Kurian V. J.

    2017-01-01

    Full Text Available Vortex Induced Vibrations (VIV may cause great damage to deep water risers. Estimation of accurate hydrodynamic coefficients and response amplitudes for fouled tubular cylinders subjected to VIVs is a complex task. This paper presents the results of an extensive experimental investigation on in-line and cross-flow forces acting on cylinders wrapped with marine growth, subjected to current at Subcritical Reynolds Number. The drag and lift force coefficients have been determined through the use of the Fast Fourier Analysis methods. The different tests were conducted in the offshore engineering laboratory at Universiti Teknologi PETRONAS (UTP, Malaysia. In this study, a cylinder with outer diameter Do = 27 mm, fixed at top as cantilever beam was used. The in-line and cross-flow forces were measured using VIV Force Totaller (VIVFT. VIVFT is a two degree of freedom (2DOF forces sensor developed by UTP to measure the VIV forces. The tests were conducted for current velocity varied between 0.118 to 0.59 m/s. The test results suggest that the cylinder wrapped with marine growth has shown an overall increase in drag and inertia coefficients as well as on response amplitudes.

  5. Ground Vibration Test Planning and Pre-Test Analysis for the X-33 Vehicle

    Science.gov (United States)

    Bedrossian, Herand; Tinker, Michael L.; Hidalgo, Homero

    2000-01-01

    This paper describes the results of the modal test planning and the pre-test analysis for the X-33 vehicle. The pre-test analysis included the selection of the target modes, selection of the sensor and shaker locations and the development of an accurate Test Analysis Model (TAM). For target mode selection, four techniques were considered, one based on the Modal Cost technique, one based on Balanced Singular Value technique, a technique known as the Root Sum Squared (RSS) method, and a Modal Kinetic Energy (MKE) approach. For selecting sensor locations, four techniques were also considered; one based on the Weighted Average Kinetic Energy (WAKE), one based on Guyan Reduction (GR), one emphasizing engineering judgment, and one based on an optimum sensor selection technique using Genetic Algorithm (GA) search technique combined with a criteria based on Hankel Singular Values (HSV's). For selecting shaker locations, four techniques were also considered; one based on the Weighted Average Driving Point Residue (WADPR), one based on engineering judgment and accessibility considerations, a frequency response method, and an optimum shaker location selection based on a GA search technique combined with a criteria based on HSV's. To evaluate the effectiveness of the proposed sensor and shaker locations for exciting the target modes, extensive numerical simulations were performed. Multivariate Mode Indicator Function (MMIF) was used to evaluate the effectiveness of each sensor & shaker set with respect to modal parameter identification. Several TAM reduction techniques were considered including, Guyan, IRS, Modal, and Hybrid. Based on a pre-test cross-orthogonality checks using various reduction techniques, a Hybrid TAM reduction technique was selected and was used for all three vehicle fuel level configurations.

  6. Test-retest reliability of muscle vibration effects on postural sway

    NARCIS (Netherlands)

    Kiers, H.; Brumagne, S.; van Dieen, J.H.; Vanhees, L.

    2014-01-01

    The effect of alterations in the processing of proprioceptive signals, on postural control, has been studied using muscle vibration effects. However, reliability and agreement of muscle vibration have still to be addressed.This study aimed to assess intra- and interday reliability and agreement of

  7. Vibration Durability Testing of Nickel Manganese Cobalt Oxide (NMC Lithium-Ion 18,650 Battery Cells

    Directory of Open Access Journals (Sweden)

    James Michael Hooper

    2016-01-01

    Full Text Available Electric vehicle (EV manufacturers are employing cylindrical format cells in the construction of the vehicles’ battery systems. There is evidence to suggest that both the academic and industrial communities have evaluated cell degradation due to vibration and other forms of mechanical loading. The primary motivation is often the need to satisfy the minimum requirements for safety certification. However, there is limited research that quantifies the durability of the battery and in particular, how the cells will be affected by vibration that is representative of a typical automotive service life (e.g., 100,000 miles. This paper presents a study to determine the durability of commercially available 18,650 cells and quantifies both the electrical and mechanical vibration-induced degradation through measuring changes in cell capacity, impedance and natural frequency. The impact of the cell state of charge (SOC and in-pack orientation is also evaluated. Experimental results are presented which clearly show that the performance of 18,650 cells can be affected by vibration profiles which are representative of a typical vehicle life. Consequently, it is recommended that EV manufacturers undertake vibration testing, as part of their technology selection and development activities to enhance the quality of EVs and to minimize the risk of in-service warranty claims.

  8. Vibration Analysis and the Accelerometer

    Science.gov (United States)

    Hammer, Paul

    2011-01-01

    Have you ever put your hand on an electric motor or motor-driven electric appliance and felt it vibrate? Ever wonder why it vibrates? What is there about the operation of the motor, or the object to which it is attached, that causes the vibrations? Is there anything "regular" about the vibrations, or are they the result of random causes? In this…

  9. Symplectic random vibration analysis of a vehicle moving on an infinitely long periodic track

    Science.gov (United States)

    Zhang, You-Wei; Lin, Jia-Hao; Zhao, Yan; Howson, W. P.; Williams, F. W.

    2010-10-01

    Based on the pseudo-excitation method (PEM), symplectic mathematical scheme and Schur decomposition, the random responses of coupled vehicle-track systems are analyzed. The vehicle is modeled as a spring-mass-damper system and the track is regarded as an infinitely long substructural chain consisting of three layers, i.e. the rails, sleepers and ballast. The vehicle and track are coupled via linear springs and the "moving-vehicle model" is adopted. The latter assumes that the vehicle moves along a static track for which the rail irregularity is further assumed to be a zero-mean valued stationary Gaussian random process. The problem is then solved efficiently as follows. Initially, PEM is used to transform the rail random excitations into deterministic harmonic excitations. The symplectic mathematical scheme is then applied to establish a low degree of freedom equation of motion with periodic coefficients. In turn these are transformed into a linear equation set whose upper triangular coefficient matrix is established using the Schur decomposition scheme. Finally, the frequency-dependent terms are separated from the load vector to avoid repeated computations for different frequencies associated with the pseudo-excitations. The proposed method is subsequently justified by comparison with a Monte-Carlo simulation; the fixed-vehicle model and the moving-vehicle model are compared and the influences of vehicle velocity and class of track on system responses are also discussed.

  10. Some Difficult-to-pass Tests of Randomness

    Directory of Open Access Journals (Sweden)

    George Marsaglia

    2002-01-01

    Full Text Available We describe three tests of randomness-- tests that many random number generators fail. In particular, all congruential generators-- even those based on a prime modulus-- fail at least one of the tests, as do many simple generators, such as shift register and lagged Fibonacci. On the other hand, generators that pass the three tests seem to pass all the tests in the Diehard Battery of Tests. Note that these tests concern the randomness of a generator's output as a sequence of independent, uniform 32-bit integers. For uses where the output is converted to uniform variates in [0,1, potential flaws of the output as integers will seldom cause problems after the conversion. Most generators seem to be adequate for producing a set of uniform reals in [0,1, but several important applications, notably in cryptography and number theory-- for example, establishing probable primes, complexity of factoring algorithms, random partitions of large integers-- may require satisfactory performance on the kinds of tests we describe here.

  11. Faster Simulation Methods for the Non-Stationary Random Vibrations of Non-Linear MDOF Systems

    DEFF Research Database (Denmark)

    Askar, A.; Köylüoglu, H. U.; Nielsen, Søren R. K.

    In this paper semi-analytical forward-difference Monte Carlo simulation procedures are proposed for the determination of the lower order statistics and the Joint Probability Density Function (JPDF) of the stochastic response of geometrically nonlinear multi-degree-of-freedom structural systems...... of motion. All of the proposed procedures yield the exact results as the time step goes to zero. The proposed procedures are based on analytical convolutions of the excitation process, hereby, reducing the generation of stochastic processes and numerical integration to the generation of random vectors only...

  12. Faster Simulation Methods for the Nonstationary Random Vibrations of Non-linear MDOF Systems

    DEFF Research Database (Denmark)

    Askar, A.; Köylüo, U.; Nielsen, Søren R.K.

    1996-01-01

    In this paper semi-analytical forward-difference Monte Carlo simulation procedures are proposed for the determination of the lower order statistics and the Joint Probability Density Function (JPDF) of the stochastic response of geometrically nonlinear multi-degree-of-freedom structural systems...... of motion. All of the proposed procedures yield the exact results as the time step goes to zero. The proposed procedures are based on analytical convolutions of the excitation process, hereby, reducing the generation of stochastic processes and numerical integration to the generation of random vectors only...

  13. Effect of whole-body vibration on neuromuscular performance and body composition for females 65 years and older: a randomized-controlled trial.

    Science.gov (United States)

    von Stengel, S; Kemmler, W; Engelke, K; Kalender, W A

    2012-02-01

    We examined whether the effect of multipurpose exercise can be enhanced by whole-body vibration (WBV). One hundred and fifty-one post-menopausal women (68.5 ± 3.1 years) were randomly assigned to three groups: (1) a training group (TG); (2) training including vibration (VTG); and (3) a wellness control group (CG). TG and VTG performed the same training program twice weekly (60 min), consisting of aerobic and strength exercises, with the only difference that leg strength exercises (15 min) were performed with (VTG) or without (TG) vibration. CG performed a low-intensity "wellness" program. At baseline and after 18 months, body composition was determined using dual-X-ray-absorptiometry. Maximum isometric strength was determined for the legs and the trunk region. Leg power was measured by countermovement jumps using a force-measuring plate. In the TG lean body mass, total body fat, and abdominal fat were favorably affected, but no additive effects were generated by the vibration stimulus. However, concerning muscle strength and power, there was a tendency in favor of the VTG. Only vibration training resulted in a significant increase of leg and trunk flexion strength compared with CG. In summary, WBV embedded in a multipurpose exercise program showed minor additive effects on body composition and neuromuscular performance. © 2010 John Wiley & Sons A/S.

  14. Children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia: A randomized controlled trial.

    Science.gov (United States)

    Bagherian, Ali; Sheikhfathollahi, Mahmood

    2016-01-01

    Topical anesthesia has been widely advocated as an important component of atraumatic administration of intraoral local anesthesia. The aim of this study was to use direct observation of children's behavioral pain reactions during local anesthetic injection using cotton-roll vibration method compared with routine topical anesthesia. Forty-eight children participated in this randomized controlled clinical trial. They received two separate inferior alveolar nerve block or primary maxillary molar infiltration injections on contralateral sides of the jaws by both cotton-roll vibration (a combination of topical anesthesia gel, cotton roll, and vibration for physical distraction) and control (routine topical anesthesia) methods. Behavioral pain reactions of children were measured according to the author-developed face, head, foot, hand, trunk, and cry (FHFHTC) scale, resulting in total scores between 0 and 18. The total scores on the FHFHTC scale ranged between 0-5 and 0-10 in the cotton-roll vibration and control methods, respectively. The mean ± standard deviation values of total scores on FHFHTC scale were lower in the cotton-roll vibration method (1.21 ± 1.38) than in control method (2.44 ± 2.18), and this was statistically significant (P anesthesia in reducing behavioral pain reactions in children during local anesthesia administration.

  15. SRG110 Stirling Generator Dynamic Simulator Vibration Test Results and Analysis Correlation

    Science.gov (United States)

    Lewandowski, Edward J.; Suarez, Vicente J.; Goodnight, Thomas W.; Callahan, John

    2007-01-01

    The U.S. Department of Energy (DOE), Lockheed Martin (LM), and NASA Glenn Research Center (GRC) have been developing the Stirling Radioisotope Generator (SRG110) for use as a power system for space science missions. The launch environment enveloping potential missions results in a random input spectrum that is significantly higher than historical radioisotope power system (RPS) launch levels and is a challenge for designers. Analysis presented in prior work predicted that tailoring the compliance at the generator-spacecraft interface reduced the dynamic response of the system thereby allowing higher launch load input levels and expanding the range of potential generator missions. To confirm analytical predictions, a dynamic simulator representing the generator structure, Stirling convertors and heat sources were designed and built for testing with and without a compliant interface. Finite element analysis was performed to guide the generator simulator and compliant interface design so that test modes and frequencies were representative of the SRG110 generator. This paper presents the dynamic simulator design, the test setup and methodology, test article modes and frequencies and dynamic responses, and post-test analysis results. With the compliant interface, component responses to an input environment exceeding the SRG110 qualification level spectrum were all within design allowables. Post-test analysis included finite element model tuning to match test frequencies and random response analysis using the test input spectrum. Analytical results were in good overall agreement with the test results and confirmed previous predictions that the SRG110 power system may be considered for a broad range of potential missions, including those with demanding launch environments.

  16. Ambient Vibration Tests of an Arch Dam with Different Reservoir Water Levels: Experimental Results and Comparison with Finite Element Modelling

    Directory of Open Access Journals (Sweden)

    Sergio Vincenzo Calcina

    2014-01-01

    Full Text Available This paper deals with the ambient vibration tests performed in an arch dam in two different working conditions in order to assess the effect produced by two different reservoir water levels on the structural vibration properties. The study consists of an experimental part and a numerical part. The experimental tests were carried out in two different periods of the year, at the beginning of autumn (October 2012 and at the end of winter (March 2013, respectively. The measurements were performed using a fast technique based on asynchronous records of microtremor time-series. In-contact single-station measurements were done by means of one single high resolution triaxial tromometer and two low-frequency seismometers, placed in different points of the structure. The Standard Spectral Ratio method has been used to evaluate the natural frequencies of vibration of the structure. A 3D finite element model of the arch dam-reservoir-foundation system has been developed to verify analytically determined vibration properties, such as natural frequencies and mode shapes, and their changes linked to water level with the experimental results.

  17. Test of Random Walk Behavior in Karachi Stock Exchange

    Directory of Open Access Journals (Sweden)

    Muhammad Mudassar

    2013-05-01

    Full Text Available Study was carried out to check the random behavior of the Karachi Stock Exchange (KSE 100 Index during the period of past three financial years to know whether investors could generate abnormal profits during the period or otherwise. Tests used were Runs Test, ADF Test, PP Test and Autocorrelation Function Test. During the study it was found that the performance of KSE 100 Index remained in weak form of inefficiency and investors have been able to generate excessive returns on their investment most of the times.

  18. Comparison of analysis and vibration test results for a multiple supported piping system

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, B.J.; Kot, C.A.; Srinivasan, M.G.

    1989-01-01

    The behavior of a nuclear power plant piping system subjected to high level vibrational excitation is investigated experimentally and analytically. The objective is to evaluate the piping analysis method employed in the SMACS computer code. Experimental data are obtained from the Large Shaker Experiments (SHAG) conducted at the HDR Test Facility in Kahl/Main, FRG, in which the dynamic behavior of an in-plant piping system with various support configurations was investigated. Comparisons of calculational results with measured data indicate that the adequacy of the prediction depends primarily on the modeling of boundary conditions and dynamic supports. Treating the latter as rigid and using building motion as input, in general, results in under prediction of piping response. On the other hand when accelerations on the pipe side of the dynamic support attachment are used as input, piping response is highly overpredicted. Also modeling wall/floor component attachments as fixed usually leads to underprediction of amplitude as well as differences in the frequency content of response. 9 refs., 18 figs., 1 tab.

  19. Tire stiffness and damping determined from static and free-vibration tests. [aircraft tires

    Science.gov (United States)

    Sleeper, R. K.; Dreher, R. C.

    1980-01-01

    Stiffness and damping of a nonrolling tire were determined experimentally from both static force-displacement relations and the free-vibration behavior of a cable-suspended platen pressed against the tire periphery. Lateral and force-and-aft spring constants and damping factors of a 49 x 17 size aircraft tire for different tire pressure and vertical loads were measured assuming a rate-independent damping form. In addition, a technique was applied for estimating the magnitude of the tire mass which participates in the vibratory motion of the dynamic tests. Results show that both the lateral and force-and-aft spring constants generally increase with tire pressure but only the latter increased significantly with vertical tire loading. The fore-and-aft spring constants were greater than those in the lateral direction. The static-spring-constant variations were similar to the dynamic variations but exhibited lower magnitudes. Damping was small and insensitive to tire loading. Furthermore, static damping accounted for a significant portion of that found dynamically. Effective tire masses were also small.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

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

  1. Distributed vibration sensing on optical fibre: field testing in borehole seismic applications

    Science.gov (United States)

    Frignet, B.; Hartog, A. H.; Mackie, D.; Kotov, O. I.; Liokumovich, L. B.

    2014-05-01

    We describe the measurement of seismic waves in a borehole using distributed vibration sensing conveyed on wireline cable. The optical measurement is compared directly with the results of a multi-level borehole seismic survey with conventional electrical accelerometers.

  2. The Influence of Amplitude- and Frequency-Dependent Stiffness of Rail Pads on the Random Vibration of a Vehicle-Track Coupled System

    Directory of Open Access Journals (Sweden)

    Kai Wei

    2016-01-01

    Full Text Available The nonlinear curves between the external static loads of Thermoplastic Polyurethane Elastomer (TPE rail pads and their compressive deformations were measured. A finite element model (FEM for a rail-fastener system was produced to determine the nonlinear compressive deformations of TPE rail pads and their nonlinear static stiffness under the static vehicle weight and the preload of rail fastener. Next, the vertical vehicle-track coupled model was employed to investigate the influence of the amplitude- and frequency-dependent stiffness of TPE rail pads on the vehicle-track random vibration. It is found that the static stiffness of TPE rail pads ranges from 19.1 to 37.9 kN/mm, apparently different from the classical secant stiffness of 26.7 kN/mm. Additionally, compared with the nonlinear amplitude- and frequency-dependent stiffness of rail pads, the classical secant stiffness would not only severely underestimate the random vibration acceleration levels of wheel-track coupled system at frequencies of 65–150 Hz but also alter the dominant frequency-distribution of vehicle wheel and steel rail. Considering that these frequencies of 65–150 Hz are the dominant frequencies of ground vibration accelerations caused by low-speed railway, the nonlinear amplitude- and frequency-dependent stiffness of rail pads should be taken into account in prediction of environment vibrations due to low-speed railway.

  3. Stochastic resonance whole body vibration increases perceived muscle relaxation but not cardiovascular activation: A randomized controlled trial.

    Science.gov (United States)

    Elfering, Achim; Burger, Christian; Schade, Volker; Radlinger, Lorenz

    2016-11-18

    To investigate the acute effects of stochastic resonance whole body vibration (SR-WBV), including muscle relaxation and cardiovascular activation. Sixty-four healthy students participated. The participants were randomly assigned to sham SR-WBV training at a low intensity (1.5 Hz) or a verum SR-WBV training at a higher intensity (5 Hz). Systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR) and self-reported muscle relaxation were assessed before and immediately after SR-WBV. Two factorial analyses of variance (ANOVA) showed a significant interaction between pre- vs post-SR-WBV measurements and SR-WBV conditions for muscle relaxation in the neck and back [F(1,55) = 3.35, P = 0.048, η2 = 0.07]. Muscle relaxation in the neck and back increased in verum SR-WBV, but not in sham SR-WBV. No significant changes between pre- and post-training levels of SBD, DBD and HR were observed either in sham or verum SR-WBV conditions. With verum SR-WBV, improved muscle relaxation was the most significant in participants who reported the experience of back, neck or shoulder pain more than once a month (P < 0.05). A single session of SR-WBV increased muscle relaxation in young healthy individuals, while cardiovascular load was low. An increase in musculoskeletal relaxation in the neck and back is a potential mediator of pain reduction in preventive worksite SR-WBV trials.

  4. Vibration Durability Testing of Nickel Cobalt Aluminum Oxide (NCA) Lithium-Ion 18650 Battery Cells

    OpenAIRE

    Hooper, James Michael; Marco, James; Chouchelamane, Gael Henri; Lyness, Christopher; Taylor, James

    2016-01-01

    This paper outlines a study undertaken to determine if the electrical performance of Nickel Cobalt Aluminum Oxide (NCA) 3.1 Ah 18650 battery cells can be degraded by road induced vibration typical of an electric vehicle (EV) application. This study investigates if a particular cell orientation within the battery assembly can result in different levels of cell degradation. The 18650 cells were evaluated in accordance with Society of Automotive Engineers (SAE) J2380 standard. This vibration tes...

  5. Designing, modelling and testing of vibration energy harvester with nonlinear stiffness

    Science.gov (United States)

    Rubes, Ondrej; Hadas, Zdenek

    2017-05-01

    This paper is focused on a design of a piezoelectric vibration energy harvester with an additional nonlinear stiffness. Common piezoelectric energy harvesters consist of a cantilever with piezoceramic layers and a tip mass for tuning up the operation frequency. This system is excited by mechanical vibrations and it provides an autonomous source of electrical energy. A linear stiffness of the cantilever has very narrow resonance frequency bandwidth which makes the piezoelectric cantilever sensitive to tuning up of the resonance frequency. It could be tuned only for one narrow vibration frequency bandwidth. The piezoelectric vibration energy harvester with nonlinear stiffness could provide the resonance frequency bandwidth wider and it allows energy harvesting from the wider bandwidth of excitation vibrations. The additional nonlinear stiffness is implemented by using a set of permanent magnets. A simulation and an experiment were performed and the results show a wider resonance bandwidth. However, it depended on direction of vibration frequency sweeping. The frequency bandwidth is more than three times wider but there is only a half resonance amplitude of oscillations. That means that the maximal harvested power is lower but the average harvested power around resonance frequency was higher which was the goal of this research.

  6. Finite-Element Vibration Analysis and Modal Testing of Graphite Epoxy Tubes and Correlation Between the Data

    Science.gov (United States)

    Taleghani, Barmac K.; Pappa, Richard S.

    1996-01-01

    Structural materials in the form of graphite epoxy composites with embedded rubber layers are being used to reduce vibrations in rocket motor tubes. Four filament-wound, graphite epoxy tubes were studied to evaluate the effects of the rubber layer on the modal parameters (natural vibration frequencies, damping, and mode shapes). Tube 1 contained six alternating layers of 30-degree helical wraps and 90-degree hoop wraps. Tube 2 was identical to tube 1 with the addition of an embedded 0.030-inch-thick rubber layer. Tubes 3 and 4 were identical to tubes 1 and 2, respectively, with the addition of a Textron Kelpoxy elastomer. This report compares experimental modal parameters obtained by impact testing with analytical modal parameters obtained by NASTRAN finite-element analysis. Four test modes of tube 1 and five test modes of tube 3 correlate highly with corresponding analytical predictions. Unsatisfactory correlation of test and analysis results occurred for tubes 2 and 4 and these comparisons are not shown. Work is underway to improve the analytical models of these tubes. Test results clearly show that the embedded rubber layers significantly increase structural modal damping as well as decrease natural vibration frequencies.

  7. Shaker Random Testing with Low Kurtosis: Review of the Methods and Application for Sigma Limiting

    Directory of Open Access Journals (Sweden)

    Alexander Steinwolf

    2010-01-01

    Full Text Available The non-Gaussian random shaker testing with kurtosis control has been known as a way of increasing the excitation crest factor in order to realistically simulate ground vehicle vibrations and other situations when the time history includes extreme peaks higher than those appearing in Gaussian random signals. However, an opposite action is also useful in other applications, particularly in modal testing. If the PSD is the only test specification, more power can be extracted from the same shaker if the crest factor is decreased and an extra space is created between the peaks of reduced height and the system abort limit. To achieve this, a technique of sigma clipping is commonly used but it generates harmonic distortions reducing dynamic range of shaker system. It is shown in the paper that the non-Gaussian phase selection in the IFFT generation can reduce kurtosis to 1.7 and bring the crest factor of drive signals from 4.5 to 2. The phase selection method does this without any loss of the controller's dynamic range that inevitably occurs after sigma clipping or polynomial transformation of time histories.

  8. Whole body vibration compared to conventional physiotherapy in patients with gonarthrosis: a protocol for a randomized, controlled study

    Directory of Open Access Journals (Sweden)

    Siewe Jan

    2010-06-01

    Full Text Available Abstract Background Osteoarthritis (OA is the most common degenerative arthropathy. Load-bearing joints such as knee and hip are more often affected than spine or hands. The prevalence of gonarthrosis is generally higher than that of coxarthrosis. Because no cure for OA exists, the main emphasis of therapy is analgesic treatment through either mobility or medication. Non-pharmacologic treatment is the first step, followed by the addition of analgesic medication, and ultimately by surgery. The goal of non-pharmacologic and non-invasive therapy is to improve neuromuscular function, which in turn both prevents formation of and delays progression of OA. A modification of conventional physiotherapy, whole body vibration has been successfully employed for several years. Since its introduction, this therapy is in wide use at our facility not only for gonarthrosis, but also coxarthrosis and other diseases leading to muscular imbalance. Methods/Design This study is a randomized, therapy-controlled trial in a primary care setting at a university hospital. Patients presenting to our outpatient clinic with initial symptoms of gonarthrosis will be assessed against inclusion and exclusion criteria. After patient consent, 6 weeks of treatment will ensue. During the six weeks of treatment, patients will receive one of two treatments, conventional physiotherapy or whole-body-vibration exercises of one hour three times a week. Follow-up examinations will be performed immediately after treatment and after another 6 and 20 weeks, for a total study duration of 6 months. 20 patients will be included in each therapy group. Outcome measurements will include objective analysis of motion and ambulation as well as examinations of balance and isokinetic force. The Western Ontario and McMaster Universities Arthritis Index and SF-12 scores, the patients' overall status, and clinical examinations of the affected joint will be carried out. Discussion As new physiotherapy

  9. Effect of 6 months of whole body vibration on lumbar spine bone density in postmenopausal women: a randomized controlled trial

    Directory of Open Access Journals (Sweden)

    Lai CL

    2013-12-01

    Full Text Available Chung-Liang Lai,1,2 Shiuan-Yu Tseng,1,2 Chung-Nan Chen,3 Wan-Chun Liao,2 Chun-Hou Wang,4 Meng-Chih Lee,1,5,* Pi-Shan Hsu5,* 1Institute of Medicine, Chung Shan Medical University, Taichung, Taiwan; 2Department of Physical Medicine and Rehabilitation, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; 3Department of Radiology, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan; 4School of Physical Therapy, Chung Shan Medical University, Taichung, Taiwan; 5Department of Family Medicine, Taichung Hospital, Ministry of Health and Welfare, Taichung, Taiwan*These authors contributed equally to this workBackground: The issue of osteoporosis-induced fractures has attracted the world's attention. Postmenopausal women are particularly at risk for this type of fracture. The nonmedicinal intervention for postmenopausal women is mainly exercise. Whole body vibration (WBV is a simple and convenient exercise. There have been some studies investigating the effect of WBV on osteoporosis; however, the intervention models and results are different. This study mainly investigated the effect of high-frequency and high-magnitude WBV on the bone mineral density (BMD of the lumbar spine in postmenopausal women.Methods: This study randomized 28 postmenopausal women into either the WBV group or the control group for a 6-month trial. The WBV group received an intervention of high-frequency (30 Hz and high-magnitude (3.2 g WBV in a natural full-standing posture for 5 minutes, three times per week, at a sports center. Dual-energy X-ray absorptiometry was used to measure the lumbar BMD of the two groups before and after the intervention.Results: Six months later, the BMD of the WBV group had significantly increased by 2.032% (P=0.047, while that of the control group had decreased by 0.046% (P=0.188. The comparison between the two groups showed that the BMD of the WBV group had increased significantly (P=0.016.Conclusion: This study found

  10. Bounds on the vibrational energy that can be harvested from random base motion

    Science.gov (United States)

    Langley, R. S.

    2015-03-01

    This paper is concerned with the development of upper bounds on the energy harvesting performance of a general multi-degree-of-freedom nonlinear electromechanical system that is subjected to random base motion and secondary applied periodic forces. The secondary forces are applied with the aim of enhancing the energy harvested from the base motion, and they may constitute direct excitation, or they may produce parametric terms in the equations of motion. It is shown that when the base motion has white noise acceleration then the power input by the base is always πS0 M / 2 where S0 is the single sided spectral density of the acceleration, and M is the mass of the system. This implies that although the secondary forces may enhance the energy harvested by causing a larger fraction of the power input from the base to be harvested rather than dissipated, there is an upper limit on the power that can be harvested. Attention is then turned to narrow band excitation, and it is found that in the absence of secondary forces a bound can be derived for a single degree of freedom system with linear damping and arbitrary nonlinear stiffness. The upper bound on the power input by the base is πM max [ S (ω) ] / 2, where S (ω) is the single sided base acceleration spectrum. The validity of this result for more general systems is found to be related to the properties of the first Wiener kernel, and this issue is explored analytically and by numerical simulation.

  11. Random Effects Structure for Confirmatory Hypothesis Testing: Keep It Maximal

    Science.gov (United States)

    Barr, Dale J.; Levy, Roger; Scheepers, Christoph; Tily, Harry J.

    2013-01-01

    Linear mixed-effects models (LMEMs) have become increasingly prominent in psycholinguistics and related areas. However, many researchers do not seem to appreciate how random effects structures affect the generalizability of an analysis. Here, we argue that researchers using LMEMs for confirmatory hypothesis testing should minimally adhere to the…

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-07-15

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

  13. Effect of a trunk-targeted intervention using vibration on posture and gait in children with spastic type cerebral palsy: a randomized control trial.

    Science.gov (United States)

    Unger, Marianne; Jelsma, Jennifer; Stark, Christina

    2013-01-01

    This study aimed to determine whether strengthening trunk muscles using vibration can improve posture and gait in children with spastic-type cerebral palsy (STCP). A total of 27 children (6-13 years) participated in a single-blinded pre-post crossover experimental trial. The 1-Minute Walk Test, 2D-posturography, ultrasound imaging and sit-ups in one minute were used to assess effect on gait, posture, resting abdominal muscle thickness and functional strength. Significant increase in distance walked (p strengthening is included in training or rehabilitation programmes. Effects of vibration on force generation and spasticity need further investigation.

  14. Stochastic resonance energy harvesting for a rotating shaft subject to random and periodic vibrations: influence of potential function asymmetry and frequency sweep

    Science.gov (United States)

    Kim, Hongjip; Che Tai, Wei; Zhou, Shengxi; Zuo, Lei

    2017-11-01

    Stochastic resonance is referred to as a physical phenomenon that is manifest in nonlinear systems whereby a weak periodic signal can be significantly amplified with the aid of inherent noise or vice versa. In this paper, stochastic resonance is considered to harvest energy from two typical vibrations in rotating shafts: random whirl vibration and periodic stick-slip vibration. Stick-slip vibrations impose a constant offset in centrifugal force and distort the potential function of the harvester, leading to potential function asymmetry. A numerical analysis based on a finite element method was conducted to investigate stochastic resonance with potential function asymmetry. Simulation results revealed that a harvester with symmetric potential function generates seven times higher power than that with asymmetric potential function. Furthermore, a frequency-sweep analysis also showed that stochastic resonance has hysteretic behavior, resulting in frequency difference between up-sweep and down-sweep excitations. An electromagnetic energy harvesting system was constructed to experimentally verify the numerical analysis. In contrast to traditional stochastic resonance harvesters, the proposed harvester uses magnetic force to compensate the offset in the centrifugal force. System identification was performed to obtain the parameters needed in the numerical analysis. With the identified parameters, the numerical simulations showed good agreement with the experiment results with around 10% error, which verified the effect of potential function asymmetry and frequency sweep excitation condition on stochastic resonance. Finally, attributed to compensating the centrifugal force offset, the proposed harvester generated nearly three times more open-circuit output voltage than its traditional counterpart.

  15. Multiaxis Rainflow Fatigue Methods for Nonstationary Vibration

    Science.gov (United States)

    Irvine, T.

    2016-01-01

    Mechanical structures and components may be subjected to cyclical loading conditions, including sine and random vibration. Such systems must be designed and tested accordingly. Rainflow cycle counting is the standard method for reducing a stress time history to a table of amplitude-cycle pairings prior to the Palmgren-Miner cumulative damage calculation. The damage calculation is straightforward for sinusoidal stress but very complicated for random stress, particularly for nonstationary vibration. This paper evaluates candidate methods and makes a recommendation for further study of a hybrid technique.

  16. Multiaxis Rainflow Fatigue Methods for Nonstationary Vibration

    Science.gov (United States)

    Irvine, T.

    2016-09-01

    Mechanical structures and components may be subjected to cyclical loading conditions, including sine and random vibration. Such systems must be designed and tested according. Rainflow cycle counting is the standard method for reducing a stress time history to a table of amplitude-cycle pairings prior to the Palmgren-Miner cumulative damage calculation. The damage calculation is straightforward for sinusoidal stress but very complicated for random stress, particularly for nonstationary vibration. This paper evaluates candidate methods and makes a recommendation for further study of a hybrid technique.

  17. Design and Execution of a Test Rig for Studying the Vibrations of a Gearbox

    Directory of Open Access Journals (Sweden)

    Zoltan Korka

    2008-10-01

    Full Text Available The current trend in the construction of gearboxes, regarding the speed increase, favours the increase of the dynamic loads which are accompanying the operation of these kinds of machines. The phenomena of dynamic contact like frictions, collisions and shocks which are taking place in cinematic couples, engines and mechanisms during their movement, are generating vibrations in a wide range of frequencies.

  18. Multi-Exciter Vibroacoustic Simulation of Hypersonic Flight Vibration

    Energy Technology Data Exchange (ETDEWEB)

    GREGORY,DANNY LYNN; CAP,JEROME S.; TOGAMI,THOMAS C.; NUSSER,MICHAEL A.; HOLLINGSHEAD,JAMES RONALD

    1999-11-11

    Many aerospace structures must survive severe high frequency, hypersonic, random vibration during their flights. The random vibrations are generated by the turbulent boundary layer developed along the exterior of the structures during flight. These environments have not been simulated very well in the past using a fixed-based, single exciter input with an upper frequency range of 2 kHz. This study investigates the possibility of using acoustic ardor independently controlled multiple exciters to more accurately simulate hypersonic flight vibration. The test configuration, equipment, and methodology are described. Comparisons with actual flight measurements and previous single exciter simulations are also presented.

  19. The Shock and Vibration Bulletin. Part 2. Model Test and Analysis, Testing Techniques, Machinery Dynamics, Isolation and Damping, Structural Dynamics

    Science.gov (United States)

    1986-08-01

    jBfr 5? JOR JS T SIONAL/lBRATIONjerF^EAR-RANCHED PROPULSION.gVSTEMS j... 117 / H.F. Tavares, Cepstrum Engenharia Ltda., Rio de Janeiro, Brazil and V...MODELLING IN FINITE ELEMENT ANALYSES OF TORSIONAL VIBRATION OF GEAR-BRANCHED PROPULSION SYSTEMS H. F. Tavares Cepstrum Engenharia Ltda. S8o Paulo

  20. An on-road shock and vibration response test series utilizing worst case and statistical analysis techniques

    Energy Technology Data Exchange (ETDEWEB)

    Cap, J.S. [Sandia National Labs., Albuquerque, NM (US). Mechanical and Thermal Environments Dept.

    1997-11-01

    Defining the maximum expected shock and vibration responses for an on-road truck transportation environment is strongly dependent on the amount of response data that can be obtained. One common test scheme consists of measuring response data over a relatively short prescribed road course and then reviewing that data to obtain the maximum response levels. The more mathematically rigorous alternative is to collect an unbiased ensemble of response data during a long road trip. This paper compares data gathered both ways during a recent on-road certification test for a tractor trailer van being designed by Sandia.

  1. Effects of 18-month low-magnitude high-frequency vibration on fall rate and fracture risks in 710 community elderly--a cluster-randomized controlled trial.

    Science.gov (United States)

    Leung, K S; Li, C Y; Tse, Y K; Choy, T K; Leung, P C; Hung, V W Y; Chan, S Y; Leung, A H C; Cheung, W H

    2014-06-01

    This study is a prospective cluster-randomized controlled clinical trial involving 710 elderly subjects to investigate the long-term effects of low-magnitude high-frequency vibration (LMHFV) on fall and fracture rates, muscle performance, and bone quality. The results confirmed that LMHFV is effective in reducing fall incidence and enhancing muscle performance in the elderly. Falls are direct causes of fragility fracture in the elderly. LMHFV has been shown to improve muscle function and bone quality. This study is to investigate the efficacy of LMHFV in preventing fall and fractures among the elderly in the community. A cluster-randomized controlled trial was conducted with 710 postmenopausal females over 60 years. A total of 364 participants received daily 20 min LMHFV (35 Hz, 0.3 g), 5 days/week for 18 months; 346 participants served as control. Fall or fracture rate was taken as the primary outcome. Also, quadriceps muscle strength, balancing abilities, bone mineral density (BMD), and quality of life (QoL) assessments were done at 0, 9, and 18 months. With an average of 66.0% compliance in the vibration group, 18.6% of 334 vibration group subjects reported fall or fracture incidences compared with 28.7% of 327 in the control (adjusted HR = 0.56, p = 0.001). The fracture rate of vibration and control groups were 1.1 and 2.3 % respectively (p = 0.171). Significant improvements were found in reaction time, movement velocity, and maximum excursion of balancing ability assessment, and also the quadriceps muscle strength (p < 0.001). No significant differences were found in the overall change of BMD. Minimal adverse effects were documented. LMHFV is effective in fall prevention with improved muscle strength and balancing ability in the elderly. We recommend its use in the community as an effective fall prevention program and to decrease related injuries.

  2. Effects of whole body vibration on bone mineral density and falls: results of the randomized controlled ELVIS study with postmenopausal women.

    Science.gov (United States)

    von Stengel, S; Kemmler, W; Engelke, K; Kalender, W A

    2011-01-01

    We determined whether the effect of exercise on bone mineral density (BMD) and falls can be enhanced by whole body vibration (WBV). In summary, the multi-purpose exercise training was effective to increase lumbar BMD but added WBV did not enhance this effect. However, falls were lowest in the exercise program combined with WBV. WBV is a new approach to reduce the risk of osteoporotic fractures. In the "Erlangen Longitudinal Vibration Study" (ELVIS), we investigated whether WBV enhances the effect of multifunctional exercise on BMD and falls. One hundred fifty-one postmenopausal women (68.5 ± 3.1 years) were randomly assigned to a: (1) conventional training group (TG); (2) conventional training group including vibration (TGV); and (3) wellness control group (CG). TG conducted an exercise program consisting of 20 min dancing aerobics, 5 min balance training, 20 min functional gymnastics, and 15 min dynamic leg-strength training on vibration plates (without vibration) twice a week. TGV performed an identical exercise regimen with vibration (25-35 Hz) during the leg-strengthening sequence. CG performed a low-intensity wellness program. BMD was measured at the hip and lumbar spine at baseline and follow-up using the DXA method. Falls were recorded daily via the calendar method. After 18 months, an increase in BMD at the lumbar spine was observed in both training groups (TGV: +1.5% vs. TG: +2.1%). The difference between the TG and the CG (1.7%) was significant. At the hip no changes were determined in either group. The fall frequency was significantly lower in TGV (0.7 falls/person) compared with CG (1.5), whereas the difference between TG (0.96) and CG was not significant. A multifunctional training program had a positive impact on lumbar BMD. The application of vibration did not enhance these effects. However, only the training including WBV affected the number of falls significantly.

  3. Structural Health Monitoring Using Wireless Technologies: An Ambient Vibration Test on the Adolphe Bridge, Luxembourg City

    Directory of Open Access Journals (Sweden)

    Adrien Oth

    2012-01-01

    Full Text Available Major threats to bridges primarily consist of the aging of the structural elements, earthquake-induced shaking and standing waves generated by windstorms. The necessity of information on the state of health of structures in real-time, allowing for timely warnings in the case of damaging events, requires structural health monitoring (SHM systems that allow the risks of these threats to be mitigated. Here we present the results of a short-duration experiment carried out with low-cost wireless instruments for monitoring the vibration characteristics and dynamic properties of a strategic civil infrastructure, the Adolphe Bridge in Luxembourg City. The Adolphe Bridge is a masonry arch construction dating from 1903 and will undergo major renovation works in the upcoming years. Our experiment shows that a network of these wireless sensing units is well suited to monitor the vibration characteristics of such a historical arch bridge and hence represents a low-cost and efficient solution for SHM.

  4. Performance testing of diesel engines using vibrational-acoustical diagnostic methods

    Energy Technology Data Exchange (ETDEWEB)

    Maack, H.H.; Neumann, G.

    1982-01-01

    Vibroacoustic condition monitoring is based on the measurement, processing and analysis of the solid-borne and airborne vibration signals emanating from a machine. Several assemblies belonging to diesel engines have a characteristic signal structure induced by impact excitation. The author proceeds from a generalised condition monitoring process to discuss the problem of the origin, transmission, measurement and analysis of vibroacoustic signals from diesel engines and presents a procedure based on a combination of frequency analysis in the temporary elimination of signal components.

  5. Influence of Whole-Body Vibration Training Without Visual Feedback on Balance and Lower-Extremity Muscle Strength of the Elderly: A Randomized Controlled Trial.

    Science.gov (United States)

    Tseng, Shiuan-Yu; Lai, Chung-Liang; Chang, Kai-Ling; Hsu, Pi-Shan; Lee, Meng-Chih; Wang, Chun-Hou

    2016-02-01

    The purpose of this study was to investigate the influence of whole-body vibration (WBV) training without visual feedback on balance and lower-extremity muscle strength in the elderly.Elderly subjects who did not exercise regularly participated in this study. Subjects were randomly divided into a WBV with eyes open group, a visual feedback-deprived plus WBV (VFDWBV) group, and a control group (0 Hz, eyes open). WBV training was provided over a 3-month period, 3 times per week for 5 min each session. Balance performance was measured with the limits of stability test, and muscle strength was measured with an isokinetic dynamometer.A total of 45 elderly subjects with an average age of 69.22  ±  3.97 years, divided into a WBV group (n = 14), a VFDWBV group (n = 17), and a control group (n = 14), completed the trial. Statistically significant differences were found in the balance performance of the 3 groups at different time points (time × group interaction: F = 13.213, P strength of the knee extensor and flexor muscles had time × group interactions: F = 29.604, P muscle strength than the WBV and control groups. The 6-month follow-up showed that the rates of hospital visits for medical services due to falls were 0% in the WBV group (0/14), 0% in the VFDWBV group (0/17), and 28.57% in the control group (4/14).Results showed that WBV training at 20  Hz without visual feedback can significantly improve the balance performance and lower-extremity muscle strength of the elderly.

  6. Analysis and testing of an integrated semi-active seat suspension for both longitudinal and vertical vibration control

    Science.gov (United States)

    Bai, Xian-Xu; Jiang, Peng; Pan, Hui; Qian, Li-Jun

    2016-04-01

    An integrated semi-active seat suspension for both longitudinal and vertical vibration control is analyzed and tested in this paper. The seat suspension consists of a switching mechanism transforming both longitudinal and vertical motions into a rotary motion and a real-time damping-controllable system-a rotary magnetorheological (MR) damper working in pure shear mode and its corresponding control system. The switching mechanism employs the parallelogram frames as a motion guide which keeps the seat moving longitudinally and vertically. At the same time, both longitudinal and vertical motions are transformed into a reciprocating rotary motion that is transmitted to the rotary MR damper after an amplification by a gear mechanism. Both the longitudinal and vertical vibrations can be attenuated in real time through controlling the damping force (or torque) of the rotary MR damper. The mathematical model of the seat suspension system is established, simulated, and analyzed. The experimental test based on the test rig in Hefei University of Technology is implemented, and the results of simulation and experimental test are compared and analyzed.

  7. Identification of dynamic characteristics by field vibration test in Tsurumi Tsubasa bridge; Tsurumi Tsubasakyo no shindo jikken ni yoru doteki tokusei no dotei

    Energy Technology Data Exchange (ETDEWEB)

    Yamaguchi, H. [Saitama University, Saitama (Japan). Faculty of Engineering; Takano, H.; Ogasawara, M.; Shimosato, T. [Metropolitan Expressway Public Corp., Tokyo (Japan); Kato, M.; Okada, J. [NKK Corp., Tokyo (Japan)

    1996-07-21

    Field vibration test of the Tsurumi Tsubasa Bridge, a long span cable stayed bridge, has been conducted. Focusing on its dynamic characteristics, an identification method from test results and its validity were investigated. The natural frequency identified using mode circle and resonance curve from steady vibration test agreed with that identified by the peak method from free damping test. Accordingly, there was no difference due to identification methods, and both methods provided appropriate accuracy. The natural vibration mode obtained from the steady vibration test agreed with that obtained by the eigenvalue analysis. The dispersion of experimental values, which indicates the adaptation to mode circle method, became a scale indicating reliability of identified values. When the damping obtained by the half power method for the microtremors test is compared with that identified from the steady vibration test and free damping test, it is required to compare them at lower amplitude level region, considering that the amplitude level of microtremors test is very low. For the dynamic characteristics of the Tsurumi Tsubasa Bridge, it was found that it has lower natural frequency and higher modal damping compared with other cable stayed bridges with similar scale of span. 18 refs., 13 figs., 4 tabs.

  8. Quantum Statistical Testing of a Quantum Random Number Generator

    Energy Technology Data Exchange (ETDEWEB)

    Humble, Travis S [ORNL

    2014-01-01

    The unobservable elements in a quantum technology, e.g., the quantum state, complicate system verification against promised behavior. Using model-based system engineering, we present methods for verifying the opera- tion of a prototypical quantum random number generator. We begin with the algorithmic design of the QRNG followed by the synthesis of its physical design requirements. We next discuss how quantum statistical testing can be used to verify device behavior as well as detect device bias. We conclude by highlighting how system design and verification methods must influence effort to certify future quantum technologies.

  9. The Shock and Vibration Bulletin: Proceedings on the Symposium on ShocK and Vibration (52nd) Held in New Orleans, Louisiana on 26-28 October 1981. Part 3. Environmental Testing and Simulation, Flight Environments.

    Science.gov (United States)

    1982-05-01

    New York, NY ITIZ AND AUTHIORS OF PAPERS PRESENTED IN THE SHORT DISCUSSION TOPICS SESSION NOTE: lb... pepere were only pneemnteo at the Symposium...system then is to create the Gunfire vibration testing is typically per- desired line spectrum, fourier transform it formed on black boxes which do not

  10. A low cycle fatigue test device for micro-cantilevers based on self-excited vibration principle.

    Science.gov (United States)

    Qi, Mingjing; Liu, Zhiwei; Yan, Xiaojun

    2014-10-01

    This paper reports a low-cycle fatigue test device for micro-cantilevers, which are widely used in micro scale structures. The working principle of the device is based on the phenomenon that a micro-cantilever can be set into self-excited vibration between two electrodes under DC voltage. Compared with previous devices, this simple device can produce large strain amplitude on non-notched specimens, and allows a batch of specimens to be tested simultaneously. Forty-two micro-cantilever specimens were tested and their fatigue fracture surfaces exhibit typical low cycle fatigue characteristics. As such, the device is very attractive for future fatigue investigation for micro scale structures.

  11. Gearbox vibration diagnostic analyzer

    Science.gov (United States)

    1992-01-01

    This report describes the Gearbox Vibration Diagnostic Analyzer installed in the NASA Lewis Research Center's 500 HP Helicopter Transmission Test Stand to monitor gearbox testing. The vibration of the gearbox is analyzed using diagnostic algorithms to calculate a parameter indicating damaged components.

  12. Urban vibrations

    DEFF Research Database (Denmark)

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

    2012-01-01

      lab   studies   in   that   we   found   a   decreased   detection   rate   in   busy   environments.   Here   we   test   with   a   much   larger   sample   and   age   range,   and   contribute   with   the   first   vibration  sensitivity  testing  outside  the  lab  in  an  urban   public...

  13. Note: A kinematic shaker system for high amplitude, low frequency vibration testing.

    Science.gov (United States)

    Swaminathan, Anand; Poese, Matthew E; Smith, Robert W M; Garrett, Steven L

    2015-11-01

    This note describes a shaker system capable of high peak-velocity, large amplitude, low frequency, near-sinusoidal excitation that has been constructed and employed in experiments on the inhibition of Rayleigh-Bénard convection using acceleration modulation. The production of high peak-velocity vibration is of interest in parametric excitation problems of this type and reaches beyond the capabilities of standard electromagnetic shakers. The shaker system described employs a kinematic linkage to two counter-rotating flywheels, driven by a variable-speed electrical motor, producing peak-to-peak displacements of 15.24 cm to a platform mounted on two guide rails. In operation, this shaker has been demonstrated to produce peak speeds of up to 3.7 m/s without failure.

  14. Analysis of Within-Test Variability of Non-Destructive Test Methods to Evaluate Compressive Strength of Normal Vibrated and Self-Compacting Concretes

    Science.gov (United States)

    Nepomuceno, Miguel C. S.; Lopes, Sérgio M. R.

    2017-10-01

    Non-destructive tests (NDT) have been used in the last decades for the assessment of in-situ quality and integrity of concrete elements. An important step in the application of NDT methods concerns to the interpretation and validation of the test results. In general, interpretation of NDT results should involve three distinct phases leading to the development of conclusions: processing of collected data, analysis of within-test variability and quantitative evaluation of property under investigation. The analysis of within-test variability can provide valuable information, since this can be compared with that of within-test variability associated with the NDT method in use, either to provide a measure of the quality control or to detect the presence of abnormal circumstances during the in-situ application. This paper reports the analysis of the experimental results of within-test variability of NDT obtained for normal vibrated concrete and self-compacting concrete. The NDT reported includes the surface hardness test, ultrasonic pulse velocity test, penetration resistance test, pull-off test, pull-out test and maturity test. The obtained results are discussed and conclusions are presented.

  15. Recommended Minimum Test Requirements and Test Methods for Assessing Durability of Random-Glass-Fiber Composites

    Energy Technology Data Exchange (ETDEWEB)

    Battiste, R.L.; Corum, J.M.; Ren, W.; Ruggles, M.B.

    1999-06-01

    This report provides recommended minimum test requirements are suggested test methods for establishing the durability properties and characteristics of candidate random-glass-fiber polymeric composites for automotive structural applications. The recommendations and suggestions are based on experience and results developed at Oak Ridge National Laboratory (ORNL) under a US Department of Energy Advanced Automotive Materials project entitled ''Durability of Lightweight Composite Structures,'' which is closely coordinated with the Automotive Composites Consortium. The report is intended as an aid to suppliers offering new structural composites for automotive applications and to testing organizations that are called on to characterize the composites.

  16. Generalized F test and generalized deviance test in two-way ANOVA models for randomized trials.

    Science.gov (United States)

    Shen, Juan; He, Xuming

    2014-01-01

    We consider the problem of detecting treatment effects in a randomized trial in the presence of an additional covariate. By reexpressing a two-way analysis of variance (ANOVA) model in a logistic regression framework, we derive generalized F tests and generalized deviance tests, which provide better power in detecting common location-scale changes of treatment outcomes than the classical F test. The null distributions of the test statistics are independent of the nuisance parameters in the models, so the critical values can be easily determined by Monte Carlo methods. We use simulation studies to demonstrate how the proposed tests perform compared with the classical F test. We also use data from a clinical study to illustrate possible savings in sample sizes.

  17. Blinded trials taken to the test: an analysis of randomized clinical trials that report tests for the success of blinding

    DEFF Research Database (Denmark)

    Hróbjartsson, A; Forfang, E; Haahr, M T

    2007-01-01

    Blinding can reduce bias in randomized clinical trials, but blinding procedures may be unsuccessful. Our aim was to assess how often randomized clinical trials test the success of blinding, the methods involved and how often blinding is reported as being successful.......Blinding can reduce bias in randomized clinical trials, but blinding procedures may be unsuccessful. Our aim was to assess how often randomized clinical trials test the success of blinding, the methods involved and how often blinding is reported as being successful....

  18. Defects detection on the welded reinforcing steel with self-shielded wires by vibration tests

    Directory of Open Access Journals (Sweden)

    Crâştiu Ion

    2017-01-01

    Full Text Available The aim of this paper is the development and validation of a vibroacustic technique to welding defects detection, especially for welded reinforcing structures. In welded structures subjected to dynamic cyclic loads may appear and propagate fatigue cracks due to local structural damage. These cracks may initiate due to the technological parameters used in welding process, or due to environmental operating conditions. By the means of Finite Element Method (FEM, the natural frequencies and shape modes of more welded steel specimens are determined. The analysis is carried out in undamaged condition as well as damaged one, after artificially induced damages. The experimental measurement of the vibroacustic response is carried out by using a condenser microphone, which is suitable for high-fidelity acoustic measurements in the frequency range of 20 – 20.000 Hz. The vibration responses of the welded specimens, in free-free conditions, are carried out using algorithms based on Fast Fourier Transform (FFT, and Prony's series. The results are compared to modal parameters estimated using FE Analysis.

  19. Permutation Test Approach for Ordered Alternatives in Randomized Complete Block Design: A Comparative Study

    OpenAIRE

    GOKPINAR, Esra; GUL, Hasan; GOKPINAR, Fikri; BAYRAK, Hülya; OZONUR, Deniz

    2013-01-01

    Randomized complete block design is one of the most used experimental designs in statistical analysis. For testing ordered alternatives in randomized complete block design, parametric tests are used if random sample are drawn from Normal distribution. If normality assumption is not provide, nonparametric methods are used. In this study, we are interested nonparametric tests and we introduce briefly the nonparametric tests, such as Page, Modified Page and Hollander tests. We also give Permutat...

  20. Integrated Vehicle Ground Vibration Testing in Support of Launch Vehicle Loads and Controls Analysis

    Science.gov (United States)

    Tuma, Margaret L.; Chenevert, Donald J.

    2009-01-01

    NASA has conducted dynamic tests on each major launch vehicle during the past 45 years. Each test provided invaluable data to correlate and correct analytical models. GVTs result in hardware changes to Saturn and Space Shuttle, ensuring crew and vehicle safety. Ares I IVGT will provide test data such as natural frequencies, mode shapes, and damping to support successful Ares I flights. Testing will support controls analysis by providing data to reduce model uncertainty. Value of testing proven by past launch vehicle successes and failures. Performing dynamic testing on Ares vehicles will provide confidence that the launch vehicles will be safe and successful in their missions.

  1. In-situ testing of the liquefaction potential of soft ground using an s-wave vibrator and seismic cones. Part 1. System, concept and preliminary test result; S ha vibrator oyobi seismic cone wo mochiita gen`ichi jiban ekijoka potential no hyoka. 1. System kosei oyobi genchi yosatsu keisoku kekka

    Energy Technology Data Exchange (ETDEWEB)

    Inazaki, T. [Public Works Research Institute, Tsukuba (Japan)

    1996-05-01

    For the purpose of evaluating liquefaction in situ, it was proposed that an S-wave vibrator designed to serve as a source in a reflection exploration method be utilized as a strong vibration generating source, and measurement was conducted in this connection. Equipment used in this test included an S-wave vibrator, static cone penetration machine, and various measuring cones. A multiplicity of measuring cones had been inserted beforehand into the target layers and comparison layers, and changes upon vibrator activation were measured. On a dry bed of the Tonegawa river, a 40m{sup 2} field was set up, and 41 cone penetration tests were conducted, with the cones positioned zigzag at 5m intervals. In this way, the ground structure was disclosed from the surface to the 10m-deep level. For the measurement, 3-component cones and seismic cones were placed at prescribed depths, and fluctuations and waveforms presented by pore water pressure at each level were determined with the vibration source changing its place. It was found that the changes in the pore water pressure exposed to vibration assume characteristic patterns corresponding to the conditions of vibration application. 5 figs., 1 tab.

  2. Effects of vibration therapy on hormone response and stress in severely disabled patients: a double-blind randomized placebo-controlled clinical trial.

    Science.gov (United States)

    Seco, J; Rodríguez-Pérez, V; López-Rodríguez, A F; Torres-Unda, J; Echevarria, E; Díez-Alegre, M I; Ortega, A; Morán, P; Mendoza-Laíz, N; Abecia Inchaurregui, L C

    2015-01-01

    To assess the effects of vibration therapy (VT) on quality of life and hormone response in severely disabled patients compared with placebo. A longitudinal prospective, double-blind, randomized placebo-controlled trial, with pre and postintervention assessments. A total of 20 severely disabled individuals were recruited from a National Reference Centre in Spain: 13 (65%) men and 7 (35%) women, 45.5 ± 9.32 years of age (range 41: 22-63). We evaluated their physical stress and state anxiety. No statistically significant changes were found in the socio-psychological variables studied, while in the experimental group state anxiety decreased significantly with p < 0.01 (Z = 2.38; one-tailed p = .009) and, among the biological variables, the level of cortisol fell (p = 0.03). Short periods of exposure to low-frequency and low-amplitude local vibration are a safe and effective mechanical stimulus that can have a positive effect in terms of hormone response. VT can be considered to have an anti-stress effect. © 2013 Association of Rehabilitation Nurses.

  3. Stochastic Modeling of Structural Uncertainty/Variability from Ground Vibration Modal Test Data (Postprint)

    Science.gov (United States)

    2012-07-01

    inclusion of a nonlinear bend–twist couple without permanent deformation of the test article. For modal testing, a Polytec PSV -400-3D scanning laser...scanned using the Polytec PSV -400-3D scanning LDV. The joined-wing test article was excited with an autoping hammer with a force sensor mounted to the

  4. A critical review of the neurophysiological evidence underlying clinical vestibular testing using sound, vibration and galvanic stimuli.

    Science.gov (United States)

    Curthoys, Ian S

    2010-02-01

    In addition to activating cochlear receptors, air conducted sound (ACS) and bone conducted vibration (BCV) activate vestibular otolithic receptors, as shown by neurophysiological evidence from animal studies--evidence which is the foundation for using ACS and BCV for clinical vestibular testing by means of vestibular-evoked myogenic potentials (VEMPs). Recent research is elaborating the specificity of ACS and BCV on vestibular receptors. The evidence that saccular afferents can be activated by ACS has been mistakenly interpreted as showing that ACS only activates saccular afferents. That is not correct - ACS activates both saccular and utricular afferents, just as BCV activates both saccular and utricular afferents, although the patterns of activation for ACS and BCV do not appear to be identical. The otolithic input to sternocleidomastoid muscle appears to originate predominantly from the saccular macula. The otolithic input to the inferior oblique appears to originate predominantly from the utricular macula. Galvanic stimulation by surface electrodes on the mastoids very generally activates afferents from all vestibular sense organs. This review summarizes the physiological results, the potential artifacts and errors of logic in this area, reconciles apparent disagreements in this field. The neurophysiological results on BCV have led to a new clinical test of utricular function - the n10 of the oVEMP. The cVEMP tests saccular function while the oVEMP tests utricular function. Copyright (c) 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  5. The Parameters Optimizing Design of Double Suspension Arm Torsion Bar in the Electric Sight-Seeing Car by Random Vibration Analyzing Method

    Directory of Open Access Journals (Sweden)

    Shui-Ting Zhou

    2017-01-01

    Full Text Available This study is about the impact of the performance and the sensitivity analysis for parameters of the torsion bar suspension in the electric sight-seeing car, which the authors’ laboratory designed and which is used in the authors’ university. The suspension stiffness was calculated by using the virtual work principle, the vector algebra, and tensor of finite rotation methods and was verified by the ADAMS software. Based on the random vibration analysis method, the paper analyzed the dynamic tire load (DTL, suspension working space (SWS, and comfort performance parameters. For the purpose of decreasing the displacement of the suspension and limiting the frequency of impacting the stop block, the paper examined the three parameters and optimized the basic parameters of the torsion bar. The results show that the method achieves a great effect and contributes an accurate value for the general layout design.

  6. Rigorously testing multialternative decision field theory against random utility models.

    Science.gov (United States)

    Berkowitsch, Nicolas A J; Scheibehenne, Benjamin; Rieskamp, Jörg

    2014-06-01

    Cognitive models of decision making aim to explain the process underlying observed choices. Here, we test a sequential sampling model of decision making, multialternative decision field theory (MDFT; Roe, Busemeyer, & Townsend, 2001), on empirical grounds and compare it against 2 established random utility models of choice: the probit and the logit model. Using a within-subject experimental design, participants in 2 studies repeatedly choose among sets of options (consumer products) described on several attributes. The results of Study 1 showed that all models predicted participants' choices equally well. In Study 2, in which the choice sets were explicitly designed to distinguish the models, MDFT had an advantage in predicting the observed choices. Study 2 further revealed the occurrence of multiple context effects within single participants, indicating an interdependent evaluation of choice options and correlations between different context effects. In sum, the results indicate that sequential sampling models can provide relevant insights into the cognitive process underlying preferential choices and thus can lead to better choice predictions. PsycINFO Database Record (c) 2014 APA, all rights reserved.

  7. The Shock and Vibration Bulletin. Part 3. Shock Testing, Shock Analysis

    Science.gov (United States)

    1974-08-01

    DYNAMICAL SYSTEMS UNDER NONSTATIONARY RANDOM EXCITATIONS T.S. Sankar and D. Doan, Sir George Williams University, Montreal, Canada MEANS OF CONTROLLING... George J. O’Hara "Effect Upon Shock ""ofthe velocity, and displacement requirements of the Dynamic Reactionof c C difficilt. A method has been...changes of step size will be required. 2 - e •,•At - (-1 The exact forms of T, M1, and M 2 may be obtained by application of the Cayley -1lamilton

  8. Diagnostic tests in Raynaud's phenomena in workers exposed to vibration: a comparative study

    DEFF Research Database (Denmark)

    Olsen, N

    1988-01-01

    C, was regarded as an abnormal response, FSP(A) test. A hand cooling, preceded by 30 minute body precooling, was performed in water at 10 degrees C during five minute ischaemia. The finger colours after hand cooling were evaluated by a directly visual inspection, FCV test, and by a blind assessment...

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

    Science.gov (United States)

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

    2000-01-01

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

  10. Effectiveness of an Occupational Health Intervention Program to Reduce Whole Body Vibration Exposure: An Evaluation Study With a Controlled Pretest-Post-test Design

    NARCIS (Netherlands)

    Tiemessen, Ivo J. H.; Hulshof, Carel T. J.; Frings-Dresen, Monique H. W.

    2009-01-01

    Background An effective intervention program aiming to reduce whole body vibration (WBV) exposure at work will reduce the number of low back complaints in the near future. Methods An evaluation study with a controlled pretest-post-test design. Nine companies and 126 drivers were included in the

  11. An evaluation of iced bridge hanger vibrations through wind tunnel testing and quasi-steady theory

    DEFF Research Database (Denmark)

    Gjelstrup, Henrik; Georgakis, Christos T.; Larsen, A.

    2012-01-01

    for wind perpendicular to the cylinder at velocities below 30 m/s and for temperatures between -5C and -1C. Aerodynamic drag, lift and moment coefficients are obtained from the static tests, whilst mean and fluctuating responses are obtained from the dynamic tests. The influence of varying surface...... roughness is also examined. The static force coefficients are used to predict parameter regions where aerodynamic instability of the iced bridge hanger might be expected to occur, through use of an adapted theoretical 3- DOF quasi-steady galloping instability model, which accounts for sectional axial...

  12. Thermoelectrically induced nonlinear free vibration analysis of piezo laminated composite conical shell panel with random fiber orientation

    Science.gov (United States)

    Lal, Achchhe; Shegokar, Niranjan L.

    2017-09-01

    This paper presents the free vibration response of piezo laminated composite geometrically nonlinear conical shell panel subjected to a thermo-electrical loading. The temperature field is assumed to be a uniform distribution over the shell surface and through the shell thickness and the electric field is assumed to be the transverse component E2 only. The material properties are assumed to be independent of the temperature and the electric field. The basic formulation is based on higher order shear deformation plate theory (HSDT) with von-Karman nonlinearity. A C0 nonlinear finite element method based on direct iterative approach is outlined and applied to solve nonlinear generalized eigenvalue problem. Parametric studies are carried out to examine the effect of amplitude ratios, stacking sequences, cone angles, piezoelectric layers, applied voltages, circumferential length to thickness ratios, change in temperatures and support boundary conditions on the nonlinear natural frequency of laminated conical shell panels. The present outlined approach has been validated with those available results in the literature.

  13. Thermoelectrically induced nonlinear free vibration analysis of piezo laminated composite conical shell panel with random fiber orientation

    Directory of Open Access Journals (Sweden)

    Lal Achchhe

    2017-09-01

    Full Text Available This paper presents the free vibration response of piezo laminated composite geometrically nonlinear conical shell panel subjected to a thermo-electrical loading. The temperature field is assumed to be a uniform distribution over the shell surface and through the shell thickness and the electric field is assumed to be the transverse component E2 only. The material properties are assumed to be independent of the temperature and the electric field. The basic formulation is based on higher order shear deformation plate theory (HSDT with von-Karman nonlinearity. A C0 nonlinear finite element method based on direct iterative approach is outlined and applied to solve nonlinear generalized eigenvalue problem. Parametric studies are carried out to examine the effect of amplitude ratios, stacking sequences, cone angles, piezoelectric layers, applied voltages, circumferential length to thickness ratios, change in temperatures and support boundary conditions on the nonlinear natural frequency of laminated conical shell panels. The present outlined approach has been validated with those available results in the literature.

  14. Evaluating vibration performance of a subsea pump module by full-scale testing and numerical modelling

    NARCIS (Netherlands)

    Beek, P.J.G. van; Pereboom, H.P.; Slot, H.J.

    2016-01-01

    Prior to subsea installation, a subsea system has to be tested to verify whether it performs in accordance with specifications and component specific performance evaluation criteria. It is important to verify that the assembled components work in accordance with the assumptions and design criteria

  15. An Evaluation of Test and Physical Uncertainty of Measuring Vibration in Wooden Junctions

    DEFF Research Database (Denmark)

    Dickow, Kristoffer Ahrens; Kirkegaard, Poul Henning; Andersen, Lars Vabbersgaard

    2012-01-01

    In the present paper a study of test and material uncertainty in modal analysis of certain wooden junctions is presented. The main structure considered here is a T-junction made from a particleboard plate connected to a spruce beam of rectangular cross section. The size of the plate is 1.2 m by 0...

  16. Extension of an Itô-based general approximation technique for random vibration of a BBW general hysteris model part II: Non-Gaussian analysis

    Science.gov (United States)

    Davoodi, H.; Noori, M.

    1990-07-01

    The work presented in this paper constitutes the second phase of on-going research aimed at developing mathematical models for representing general hysteretic behavior of structures and approximation techniques for the computation and analysis of the response of hysteretic systems to random excitations. In this second part, the technique previously developed by the authors for the Gaussian response analysis of non-linear systems with general hysteretic behavior is extended for the non-Gaussian analysis of these systems. This approximation technique is based on the approach proposed independently by Ibrahim and Wu-Lin. In this work up to fourth order moments of the response co-ordinates are obtained for the Bouc-Baber-Wen smooth hysteresis model. These higher order statistics previously have not been made available for general hysteresis models by using existing approximation methods. Second order moments obtained for the model by this non-Gaussian closure scheme are compared with equivalent linearization and Gaussian closure results via Monte Carlo simulation (MCS). Higher order moments are compared with the simulation results. The study performed for a wide range of degradation parameters and input power spectral density ( PSD) levels shows that the non-Gaussian responses obtained by this approach are in better agreement with the MCS results than the linearized and Gaussian ones. This approximation technique can provide information on higher order moments for general hysteretic systems. This information is valuable in random vibration and the reliability analysis of hysteretically yielding structures.

  17. Vibrating Platform Training Improves Respiratory Muscle Strength, Quality of Life, and Inspiratory Capacity in the Elderly Adults: A Randomized Controlled Trial.

    Science.gov (United States)

    Pessoa, Maíra Florentino; Brandão, Daniela Cunha; Sá, Rafaela Barros de; Barcelar, Jacqueline de Melo; Rocha, Taciano Dias de Souza; Souza, Helga Cecília Muniz de; Dornelas de Andrade, Armele

    2017-05-01

    Aging affects respiratory strength that could cause reduction in functional capacity and quality of life, playing a fundamental role in healthy aging and survival. To prevent these declines, the whole body vibration (WBV) has been proposed to increase strength and functional capacity. The aim of the study was to evaluate the effects of WBV on respiratory muscle strength, thoracoabdominal ventilation, and quality of life in the elderly adults. This study was a controlled, randomized double-blind clinical trial. The study included 28 elderly adults randomized into three groups: Resistance (n = 9), WBV (n = 9), or WBV + resistance exercises (n = 10), performing training, sham, or double training for 3 months, twice per week. The variables of the study were as follows: maximal inspiratory and expiratory pressures (MIP and MEP), distribution of thoracoabdominal volumes variation in optoelectronic plethysmography (pulmonary rib cage-VRCp, abdominal rib cage-VRCa, and abdomen-VAB), and quality of life. After training, WBV and WBV + resistance groups increased MIP and MEP (p training that could improve respiratory muscle strength and quality of life and promote different ventilatory strategies in chest wall and thoracoabdominal compartments in healthy elderly adults.

  18. Randomized trial testing the effect of peer education at increasing fruit and vegetable intake

    National Research Council Canada - National Science Library

    Buller, D B; Morrill, C; Taren, D; Aickin, M; Sennott-Miller, L; Buller, M K; Larkey, L; Alatorre, C; Wentzel, T M

    1999-01-01

    .... In a randomized trial, peer education was tested for effectiveness at increasing fruit and vegetable intake among lower socioeconomic, multicultural labor and trades employees. Employees (n = 2091...

  19. Prognostic and Remaining Life Prediction of Electronic Device under Vibration Condition Based on CPSD of MPI

    Directory of Open Access Journals (Sweden)

    Ying Chen

    2016-01-01

    Full Text Available Prognostic of electronic device under vibration condition can help to get information to assist in condition-based maintenance and reduce life-cycle cost. A prognostic and remaining life prediction method for electronic devices under random vibration condition is proposed. Vibration response is measured and monitored with acceleration sensor and OMA parameters, including vibration resonance frequency, especially first-order resonance frequency, and damping ratio is calculated with cross-power spectrum density (CPSD method and modal parameter identification (MPI algorithm. Steinberg vibration fatigue model which considers transmissibility factor is used to predict the remaining life of electronic component. Case study with a test board is carried out and remaining life is predicted. Results show that with this method the vibration response characteristic can be monitored and predicted.

  20. Vibration Testing Procedures for Bone Stiffness Assessment in Fractures Treated with External Fixation.

    Science.gov (United States)

    Mattei, Lorenza; Longo, Antonia; Di Puccio, Francesca; Ciulli, Enrico; Marchetti, Stefano

    2017-04-01

    A bone healing assessment is crucial for the successful treatment of fractures, particularly in terms of the timing of support devices. However, in clinical practice, this assessment is only made qualitatively through bone manipulation and X-rays, and hence cannot be repeated as often as might be required. The present study reconsiders the quantitative method of frequency response analysis for healing assessments, and specifically for fractures treated with an external fixator. The novelty consists in the fact that bone excitation and response are achieved through fixator pins, thus overcoming the problem of transmission through soft-tissues and their damping effect. The main objective was to develop and validate a test procedure in order to characterize the treated bone. More than 80 tests were performed on a tibia phantom alone, a phantom with pins, and a phantom with a complete fixator. Different excitation techniques and input-output combinations were compared. The results demonstrated the effectiveness of a procedure based on impact tests using a micro-hammer. Pins and fixator were demonstrated to influence the frequency response of the phantom by increasing the number of resonant frequencies. This procedure will be applied in future studies to monitor healing both in in vitro and in vivo conditions.

  1. Experimental Issues in Testing a Semiactive Technique to Control Earthquake Induced Vibration

    Directory of Open Access Journals (Sweden)

    Nicola Caterino

    2014-01-01

    Full Text Available This work focuses on the issues to deal with when approaching experimental testing of structures equipped with semiactive control (SA systems. It starts from practical experience authors gained in a recent wide campaign on a large scale steel frame structure provided with a control system based on magnetorheological dampers. The latter are special devices able to achieve a wide range of physical behaviours using low-power electrical currents. Experimental activities involving the use of controllable devices require special attention in solving specific aspects that characterize each of the three phases of the SA control loop: acquisition, processing, and command. Most of them are uncommon to any other type of structural testing. This paper emphasizes the importance of the experimental assessment of SA systems and shows how many problematic issues likely to happen in real applications are also present when testing these systems experimentally. This paper highlights several problematic aspects and illustrates how they can be addressed in order to achieve a more realistic evaluation of the effectiveness of SA control solutions. Undesired and unavoidable effects like delays and control malfunction are also remarked. A discussion on the way to reduce their incidence is also offered.

  2. The effects of two different frequencies of whole-body vibration on knee extensors strength in healthy young volunteers: a randomized trial

    Science.gov (United States)

    Esmaeilzadeh, S.; Akpinar, M.; Polat, S.; Yildiz, A.; Oral, A.

    2015-01-01

    The aim of this study was to investigate the effects of two different frequencies of whole-body vibration (WBV) training on knee extensors muscle strength in healthy young volunteers. Twenty-two eligible healthy untrained young women aged 22-31 years were allocated randomly to the 30-Hz (n=11) and 50-Hz (n=11) groups. They participated in a supervised WBV training program that consisted of 24 sessions on a synchronous vertical vibration platform (peak-to-peak displacement: 2-4 mm; type of exercises: semi-squat, one-legged squat, and lunge positions on right leg; set numbers: 2-24) three times per week for 8 weeks. Isometric and dynamic strength of the knee extensors were measured prior to and at the end of the 8-week training. In the 30-Hz group, there was a significant increase in the maximal voluntary isometric contraction (p=0.039) and the concentric peak torque (p=0.018) of knee extensors and these changes were significant (p<0.05) compared with the 50-Hz group. In addition, the eccentric peak torque of knee extensors was increased significantly in both groups (p<0.05); however, there was no significant difference between the two groups (p=0.873). We concluded that 8 weeks WBV training in 30 Hz was more effective than 50 Hz to increase the isometric contraction and dynamic strength of knee extensors as measured using peak concentric torque and equally effective with 50 Hz in improving eccentric torque of knee extensors in healthy young untrained women. PMID:26636279

  3. The effects of whole body vibration in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

    Directory of Open Access Journals (Sweden)

    Caroline C. Robinson

    2015-01-01

    Full Text Available Background:Whole body vibration (WBV has been used to increase physical activity levels in patients with type 2 diabetes mellitus (T2DM.Objective:To carry out a systematic review of the effects of WBV on the glycemic control, cardiovascular risk factors, and physical and functional capacity of patients with T2DM.Method: MEDLINE, LILACS, PEDro, and Cochrane Central Register of Controlled Trials were searched up to June 1st, 2015. Randomized controlled trials investigating the effects of WBV, compared to control or other intervention, on blood glucose levels, blood and physical cardiovascular risk factors, and physical and functional capacity in adult individuals with T2DM. Two independent reviewers extracted the data regarding authors, year of publication, number of participants, gender, age, WBV parameters and description of intervention, type of comparison, and mean and standard deviation of pre and post assessments.Results: Out of 585 potentially eligible articles, two studies (reported in four manuscripts were considered eligible. WBV interventions provided a significant reduction of 25.7 ml/dl (95% CI:-45.3 to -6.1; I2: 19% in 12 hours fasting blood glucose compared with no intervention. Improvements in glycated hemoglobin, cardiovascular risk factors, and physical and functional capacity were found only at 12 weeks after WBV intervention in comparison with no intervention.Conclusion: WBV combined with exercise seems to improve glycemic control slightly in patients with T2DM in an exposure-dependent way. Large and well-designed trials are still needed to establish the efficacy and understand whether the effects were attributed to vibration, exercise, or a combination of both.

  4. The effects of whole body vibration in patients with type 2 diabetes: a systematic review and meta-analysis of randomized controlled trials

    Science.gov (United States)

    Robinson, Caroline C.; Barreto, Rodrigo P. G.; Sbruzzi, Graciele; Plentz, Rodrigo D. M.

    2015-01-01

    Background: Whole body vibration (WBV) has been used to increase physical activity levels in patients with type 2 diabetes mellitus (T2DM). Objective: To carry out a systematic review of the effects of WBV on the glycemic control, cardiovascular risk factors, and physical and functional capacity of patients with T2DM. Method: MEDLINE, LILACS, PEDro, and Cochrane Central Register of Controlled Trials were searched up to June 1st, 2015. Randomized controlled trials investigating the effects of WBV, compared to control or other intervention, on blood glucose levels, blood and physical cardiovascular risk factors, and physical and functional capacity in adult individuals with T2DM. Two independent reviewers extracted the data regarding authors, year of publication, number of participants, gender, age, WBV parameters and description of intervention, type of comparison, and mean and standard deviation of pre and post assessments. Results: Out of 585 potentially eligible articles, two studies (reported in four manuscripts) were considered eligible. WBV interventions provided a significant reduction of 25.7 ml/dl (95% CI:-45.3 to -6.1; I2: 19%) in 12 hours fasting blood glucose compared with no intervention. Improvements in glycated hemoglobin, cardiovascular risk factors, and physical and functional capacity were found only at 12 weeks after WBV intervention in comparison with no intervention. Conclusion: WBV combined with exercise seems to improve glycemic control slightly in patients with T2DM in an exposure-dependent way. Large and well-designed trials are still needed to establish the efficacy and understand whether the effects were attributed to vibration, exercise, or a combination of both. PMID:26578253

  5. Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Engineering Test Report: AMSU-A2 METSAT Instrument (S/N 108) Acceptance Level Vibration Tests of Dec 1999/Jan 2000 (S/O 784077, OC-454)

    Science.gov (United States)

    Heffner, R.

    2000-01-01

    This is the Engineering Test Report, AMSU-A2 METSAT Instrument (S/N 108) Acceptance Level Vibration Test of Dec 1999/Jan 2000 (S/O 784077, OC-454), for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A).

  6. Field Test Data for Detecting Vibrations of a Building Using High-Speed Video Cameras

    Science.gov (United States)

    2017-10-01

    5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army Research Laboratory ATTN: RDRL-SES-P 2800 Powder Mill Road...The team set up a low-frequency ServoDrive speaker inside of ARL’s Building 108 facility. In this experiment, the speaker generated tones at 19, 28...ground-truth data. The field test and the data collected are documented in this report. The team developed image processing algorithms to analyze the

  7. Randomly Amplified Polymorphic DNA tests (RAPDs) cannot be ...

    African Journals Online (AJOL)

    The three South African crane species — the Blue Crane (Anthropoides paradisea), the Wattled Crane (Bugeranus carunculatus) and the Grey Crowned Crane (Balearica regulorum regulorum) — are listed as threatened by the IUCN. This study investigated the suitability of Randomly Amplified Polymorphic DNA markers in ...

  8. Analysis and testing of an inner bypass magnetorheological damper for shock and vibration mitigation

    Science.gov (United States)

    Bai, Xian-Xu; Hu, Wei; Wereley, Norman M.

    2013-04-01

    Aiming at fundamentally improving the performance of MR dampers, including maximizing dynamic range (i.e., ratio of field-on to field-off damping force) while simultaneously minimizing field-off damping force, this study presents the principle of an inner bypass magnetorheological damper (IBMRD). The IBMRD is composed of a pair of twin tubes, i.e., the inner tube and outer concentric tube, a movable piston-shaft arrangement, and an annular MR fluid flow gap sandwiched between the concentric tubes. In the IBMRD, the inner tube serves simultaneously as the guide for the movable piston and the bobbin for the electromagnetic coil windings, and five active rings on the inner tube, annular MR fluid flow gap, and outer tube forms five closed magnetic circuits. The annular fluid flow gap is an inner bypass annular valve where the rheology of the MR fluids, and hence the damping force of the MR damper, is controlled. Based on the structural principle of the IBMRD, the IBMRD is configured and its finite element analysis (FEA) is implemented. After theoretically constructing the hydro-mechanical model for the IBMRD, its mathematical model is established using a Bingham-plastic nonlinear fluid model. The characteristics of the IBMRD are theoretically evaluated and compared to those of a conventional piston-bobbin MR damper with an identical active length and cylinder diameter. In order to validate the theoretical results predicted by the mathematical model, the prototype IBMRD is designed, fabricated, and tested. The servo-hydraulic testing machine (type: MTS 810) and rail-guided drop tower are used to provide sinusoidal displacement excitation and shock excitation to the IBMRD, respectively.

  9. Testing and performance of a new friction damper for seismic vibration control

    Science.gov (United States)

    Martínez, Carlos A.; Curadelli, Oscar

    2017-07-01

    In the last two decades, great efforts were carried out to reduce the seismic demand on structures through the concept of energy dissipation instead of increasing the stiffness and strength. Several devices based on different energy dissipation principles have been developed and implemented worldwide, however, most of the dissipation devices are usually installed using diagonal braces, which entail certain drawbacks on apertures for circulation, lighting or ventilation and architectural or functional requirements often preclude this type of installations. In this work, a conceptual development of a novel energy dissipation device, called Multiple Friction Damper (MFD), is proposed and examined. To verify its characteristics and performance, the MFD was implemented on a single storey steel frame experimental model and tested under different conditions of normal force and real time acceleration records. Experimental results demonstrated that the new MFD constitutes an effective and reliable alternative to control the structural response in terms of displacement and acceleration. A mathematical formulation based on the Wen's model reflecting the nonlinear behaviour of the device is also presented.

  10. Qualification of the JWST MIRI Instrument Using Force Limited Vibration

    Science.gov (United States)

    Sykes, J.; Eccleston, P.; Laine, B.; Ngan, I.; Salvignol, J. C.

    2012-07-01

    The MIRI instrument design was qualified for sine and random environments using force limited testing to limit the dynamic responses of the sensitive optical components and mechanisms while demonstrating adequate margin with regard to the environmental flight conditions. Force limiting was achieved using force transducers located between the interface of the instrument and the shaker adapter during the vibration test. Interface forces for each of the three interface points were measured in three orthogonal axes during the low level sine test and used to compute the overturning moment, while the resulting global interface force was directly measured by combining the signals from three individual interfaces during the high level vibrations such that automatic notching could be applied. The test was performed in the recently upgraded vibration facility of the Rutherford Appleton Laboratory. In order to demonstrate and develop the MIRI flight model test approach and procedures, a pull- through test was carried out using the Structural Model of the instrument which had been previously vibrated in 2005 at a different facility. This early test allowed measurement of the facility behaviour with the test article, exercising the notching and abort functions, and highlighting an issue with the stiffness of the adapter, as well as several other lessons learned. An adapter with additional in-plane stiffness to ensure in-phase movement of the interfaces and correct functioning of the force-limiting system was subsequently designed, manufactured and tested in time for the instrument FM test. The vibration test was executed very smoothly thanks to the lessons learned from the preparatory test and the work carried out by the team in advance of the test in preparing modelling and analysis tools which could be used in quasi-real time during the test campaign. The paper intends to present the force limited vibration notching approach as well as the lessons learned from this test.

  11. On random field Completely Automated Public Turing Test to Tell Computers and Humans Apart generation.

    Science.gov (United States)

    Kouritzin, Michael A; Newton, Fraser; Wu, Biao

    2013-04-01

    Herein, we propose generating CAPTCHAs through random field simulation and give a novel, effective and efficient algorithm to do so. Indeed, we demonstrate that sufficient information about word tests for easy human recognition is contained in the site marginal probabilities and the site-to-nearby-site covariances and that these quantities can be embedded directly into certain conditional probabilities, designed for effective simulation. The CAPTCHAs are then partial random realizations of the random CAPTCHA word. We start with an initial random field (e.g., randomly scattered letter pieces) and use Gibbs resampling to re-simulate portions of the field repeatedly using these conditional probabilities until the word becomes human-readable. The residual randomness from the initial random field together with the random implementation of the CAPTCHA word provide significant resistance to attack. This results in a CAPTCHA, which is unrecognizable to modern optical character recognition but is recognized about 95% of the time in a human readability study.

  12. Hand function tests and questions on hand symptoms as related to the Stockholm workshop scales for diagnosis of hand-arm vibration syndrome.

    Science.gov (United States)

    Cederlund, R; Iwarsson, S; Lundborg, G

    2003-04-01

    The severity of hand-arm vibration syndrome (HAVS) is usually graded according to the Stockholm workshop scales. Although the Stockholm workshop scales are regarded the gold standard for assessing the severity of HAVS, they are based primarily on subjective symptoms. The aim of the present study was to explore the agreement between Stockholm workshop scales and the outcome from ten well-defined clinical tests commonly used in hand rehabilitation for assessment of hand function. One hundred and eleven vibration-exposed workers participated in the study. Ten objective tests of hand function and four questions on subjective hand symptoms were included. The results indicated that, out of these tests, perception of vibration, perception of touch/pressure and dexterity showed a moderate agreement with Stockholm workshop scales. Among specific questions on hand symptoms, cold intolerance and pain showed a high agreement with Stockholm workshop scales. It is concluded that defined objective tests combined with directed questions on specific hand symptoms, together with the Stockholm workshop scales, may be helpful for diagnosing HAVS.

  13. Effect of vibration on visual display terminal work performance.

    Science.gov (United States)

    Hsieh, Yao-Hung; Lin, Chiuhsiang Joe; Chen, Hsiao-Ching

    2007-12-01

    Today electronic visual displays have dramatic use in daily life. Reading these visual displays is subject to their vibration. Using a software-simulation of a vibrated environment, the study investigated the effect of vibration on visual performance and fatigue for several numerical display design characteristics including the font size and the number of digits displayed. Both the frequency and magnitude of vibration had significant effects on the reaction time, accuracy, and visual fatigue. 10 graduate students (23-30 years old; M = 25.6), randomly tested in this experiment, were offered about 25 U.S. dollars for their participation. Numbers in vertical presentation were affected more in vertical vibration than those in horizontal presentation. Analysis showed whenever the display is used in vibration environment, an increased font size may be an effective way to compensate the adverse effect of vibration. The software design of displayed materials must be designed to take the motion effect into consideration to increase the quality of the screen display.

  14. Effects of long-term whole-body vibration training on mobility in patients with multiple sclerosis: A meta-analysis of randomized controlled trials.

    Science.gov (United States)

    Kantele, Sini; Karinkanta, Saija; Sievänen, Harri

    2015-11-15

    This meta-analysis evaluated feasibility and efficacy of long-term whole-body vibration (WBV) training in improving mobility of multiple sclerosis (MS) patients. The primary search of this meta-analysis was conducted from four electronic databases (PubMed, Sport, CINAHL and Cochrane) in order to find all relevant randomized, controlled WBV intervention trials of MS patients published between January 2000 and October 2013. The primary search was complemented by a recent (Aug 2015) PubMed search. Data on patients' characteristics and type of WBV intervention were extracted from the published reports and supplementary material. Two researchers independently assessed the methodological quality of these studies and outcomes. Standardized mean differences based on the baseline-adjusted follow-up results were calculated as indicators of the effect size (ES) of WBV training. Seven randomized controlled trials (RCTs) involving 250 MS patients were found. Relevant group-based data for analysis were available from 109 patients in WBV groups and from 100 control patients; 41 patients withdrew from the studies. Quality assessment revealed that the WBV training protocols were heterogeneous and the methodological quality of the studies was generally poor. We found borderline indication for improved 2-6 min walking endurance [ES=0.25 (95% CI=-0.06-0.0.55)] favoring WBV training whereas no benefits were indicated for short-distance (20m or less) walking speed or balance. This meta-analysis suggests that WBV training has potential in improving walking endurance in MS patients with low disability status. However, evidence for more severely disabled MS patients is lacking, and further well-designed, long-term RCTs with adequate sample sizes are needed. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Is two better than one? Muscle vibration plus robotic rehabilitation to improve upper limb spasticity and function: A pilot randomized controlled trial.

    Science.gov (United States)

    Calabrò, Rocco Salvatore; Naro, Antonino; Russo, Margherita; Milardi, Demetrio; Leo, Antonino; Filoni, Serena; Trinchera, Antonia; Bramanti, Placido

    2017-01-01

    Even though robotic rehabilitation is very useful to improve motor function, there is no conclusive evidence on its role in reducing post-stroke spasticity. Focal muscle vibration (MV) is instead very useful to reduce segmental spasticity, with a consequent positive effect on motor function. Therefore, it could be possible to strengthen the effects of robotic rehabilitation by coupling MV. To this end, we designed a pilot randomized controlled trial (Clinical Trial NCT03110718) that included twenty patients suffering from unilateral post-stroke upper limb spasticity. Patients underwent 40 daily sessions of Armeo-Power training (1 hour/session, 5 sessions/week, for 8 weeks) with or without spastic antagonist MV. They were randomized into two groups of 10 individuals, which received (group-A) or not (group-B) MV. The intensity of MV, represented by the peak acceleration (a-peak), was calculated by the formula (2πf)2A, where f is the frequency of MV and A is the amplitude. Modified Ashworth Scale (MAS), short intracortical inhibition (SICI), and Hmax/Mmax ratio (HMR) were the primary outcomes measured before and after (immediately and 4 weeks later) the end of the treatment. In all patients of group-A, we observed a greater reduction of MAS (p = 0.007, d = 0.6) and HMR (prehabilitative approach could be a promising option in improving upper limb spasticity and motor function. We could hypothesize that the greater rehabilitative outcome improvement may depend on a reshape of corticospinal plasticity induced by a sort of associative plasticity between Armeo-Power and MV.

  16. Is two better than one? Muscle vibration plus robotic rehabilitation to improve upper limb spasticity and function: A pilot randomized controlled trial

    Science.gov (United States)

    Russo, Margherita; Milardi, Demetrio; Leo, Antonino; Filoni, Serena; Trinchera, Antonia; Bramanti, Placido

    2017-01-01

    Even though robotic rehabilitation is very useful to improve motor function, there is no conclusive evidence on its role in reducing post-stroke spasticity. Focal muscle vibration (MV) is instead very useful to reduce segmental spasticity, with a consequent positive effect on motor function. Therefore, it could be possible to strengthen the effects of robotic rehabilitation by coupling MV. To this end, we designed a pilot randomized controlled trial (Clinical Trial NCT03110718) that included twenty patients suffering from unilateral post-stroke upper limb spasticity. Patients underwent 40 daily sessions of Armeo-Power training (1 hour/session, 5 sessions/week, for 8 weeks) with or without spastic antagonist MV. They were randomized into two groups of 10 individuals, which received (group-A) or not (group-B) MV. The intensity of MV, represented by the peak acceleration (a-peak), was calculated by the formula (2πf)2A, where f is the frequency of MV and A is the amplitude. Modified Ashworth Scale (MAS), short intracortical inhibition (SICI), and Hmax/Mmax ratio (HMR) were the primary outcomes measured before and after (immediately and 4 weeks later) the end of the treatment. In all patients of group-A, we observed a greater reduction of MAS (p = 0.007, d = 0.6) and HMR (pspastic muscles (p = 0.004). Our data show that this combined rehabilitative approach could be a promising option in improving upper limb spasticity and motor function. We could hypothesize that the greater rehabilitative outcome improvement may depend on a reshape of corticospinal plasticity induced by a sort of associative plasticity between Armeo-Power and MV. PMID:28973024

  17. Sleep improvement for restless legs syndrome patients. Part I: pooled analysis of two prospective, double-blind, sham-controlled, multi-center, randomized clinical studies of the effects of vibrating pads on RLS symptoms

    Directory of Open Access Journals (Sweden)

    Burbank F

    2013-04-01

    Full Text Available Fred Burbank,1 Mark J Buchfuhrer,2 Branko Kopjar31Salt Creek International Women’s Health Foundation, San Clemente, CA, USA; 2Stanford University Center for Sleep Sciences, Downey, CA, USA; 3Department of Health Services, University of Washington, Seattle, WA, USAPurpose: Pooled data from two randomized, double-blind, prospective clinical trials were analyzed (i to determine if vibratory stimulation can safely treat patients with moderately severe restless legs syndrome and (ii to compare two types of shams.Patients and methods: One hundred and fifty-eight patients with at least moderately severe primary restless legs syndrome (a score of 15 or greater on the International Restless Legs Syndrome Study Group rating scale were enrolled at five investigational sites, between April 20, 2009 and February 12, 2010. Patients were randomly assigned to treatment with a vibrating pad or control (sound-producing or light-emitting sham pad. Patients and investigators were blinded to pad assignment type (treatment pad or sham pad. Efficacy was measured as a change in score from baseline to week 4, on the Medical Outcomes Study Sleep Problems Index II, the Johns Hopkins Restless Legs Syndrome Quality of Life summary scale, and the International Restless Legs Syndrome Study Group rating scale. Clinicians were asked to evaluate the effectiveness of the pad assignment and to guess whether treatment or sham therapy had been assigned. Adverse events related to vibrating pad assignment were tabulated.Results: The Medical Outcomes Study Sleep Problems Index II scores improved significantly more for patients receiving a vibrating pad over those receiving a sham pad (P ≤ 0.02 even when corrected for multiplicity (P ≤ 0.04. Clinician evaluation favored patients assigned vibrating pads, and neither patients nor clinicians accurately guessed which pad was assigned. No significant difference in adverse event rates was observed between the vibrating and sham pad

  18. Using Chest Vibration Nursing Intervention to Improve Expectoration of Airway Secretions and Prevent Lung Collapse in Ventilated ICU Patients: A Randomized Controlled Trial

    Directory of Open Access Journals (Sweden)

    Yu-Chih Chen

    2009-06-01

    Conclusion: The results suggest that chest vibration may contribute to expectoration and thus improve lung collapse among ventilated patients in an ICU. Chest vibration nursing intervention is a safe and effective alternative pulmonary clearance method and can be used on patients who are on ventilators in ICUs.

  19. Whole-body vibration dosage alters leg blood flow

    NARCIS (Netherlands)

    Lythgo, Noel; Eser, Prisca; de Groot, Patricia; Galea, Mary

    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used

  20. An Ultra-light PRNG Passing Strict Randomness Tests and Suitable for Low Cost Tags

    Directory of Open Access Journals (Sweden)

    OZCANHAN, M. H.

    2016-08-01

    Full Text Available A pseudo-random number generator for low-cost RFID tags is presented. The scheme is simple, sequential and secure, yet has a high performance. Despite its lowest hardware complexity, our proposal represents a better alternative than previous proposals for low-cost tags. The scheme is based on the well-founded pseudo random number generator, Mersenne Twister. The proposed generator takes low-entropy seeds extracted from a physical characteristic of the tag and produces outputs that pass popular randomness tests. Contrarily, previous proposal tests are based on random number inputs from a popular online source, which are simply unavailable to tags. The high performance and satisfactory randomness of present work are supported by extensive test results and compared with similar previous works. Comparison using proven estimation formulae indicates that our proposal has the best hardware complexity, power consumption, and the least cost.

  1. Imaging performance comparison between CMOS and sCMOS detectors in a vibration test on large areas using digital holographic interferometry

    Science.gov (United States)

    Flores-Morenoa, J. M.; Torre I., Manuel H. De la; Aguayo, Daniel D.; Fernando Mendoza, S.

    2014-05-01

    A comparison of the interferometric imaging performance of two different cameras during a vibration study is presented. One of the cameras has a high speed CMOS sensor and the second one uses a high resolution (scientific) sCMOS sensor. This comparison is based on the interferometric response as a merit parameter of these sensors which is not a conventional procedure. Even when the current standard for image quality is on the signal to noise ratio calculations, an interferometric test to evaluate the fringe pattern visibility is equivalent to the contrast to noise ratio value. An out of plane digital holographic interferometer is used to test each camera once at the time with the same experimental conditions. The object under study is a metallically framed table with a Formica cover with an observable area of 1.1 m2. The sample is deformed by means of a controlled vibration induced by a tip ended linear step motor. Results from each camera are presented as the retrieved optical phase during the vibration. Finally, some conclusions based on the post processed images are presented suggesting a smoother optical phase obtained with the sCMOS camera.

  2. Calculation and analysis of the harmonic vibrational frequencies in molecules at extreme pressure: Methodology and diborane as a test case

    Science.gov (United States)

    Cammi, R.; Cappelli, C.; Mennucci, B.; Tomasi, J.

    2012-10-01

    We present a new quantum chemical method for the calculation of the equilibrium geometry and the harmonic vibrational frequencies of molecular systems in dense medium at high pressures (of the order of GPa). The new computational method, named PCM-XP, is based on the polarizable continuum model (PCM), amply used for the study of the solvent effects at standard condition of pressure, and it is accompanied by a new method of analysis for the interpretation of the mechanisms underpinning the effects of pressure on the molecular geometries and the harmonic vibrational frequencies. The PCM-XP has been applied at the density functional theory level to diborane as a molecular system under high pressure. The computed harmonic vibrational frequencies as a function of the pressure have shown a satisfactory agreement with the corresponding experimental results, and the parallel application of the method of analysis has reveled that the effects of the pressure on the equilibrium geometry can be interpreted in terms of direct effects on the electronic charge distribution of the molecular solutes, and that the effects on the harmonic vibrational frequencies can be described in terms of two physically distinct effects of the pressure (curvature and relaxation) on the potential energy for the motion of the nuclei.

  3. Random regression test-day model for the analysis of dairy cattle ...

    African Journals Online (AJOL)

    Random regression test-day model for the analysis of dairy cattle production data in South Africa: Creating the framework. EF Dzomba, KA Nephawe, AN Maiwashe, SWP Cloete, M Chimonyo, CB Banga, CJC Muller, K Dzama ...

  4. T3, a Combinator-based Random Testing Tool for Java: Benchmarking

    NARCIS (Netherlands)

    Prasetya, I.S.W.B.

    2014-01-01

    T3 is the next generation of the light weight automated testing tool T2 for Java. In the heart T3 is still a random testing tool; but it now comes with some new features: pair-wise testing, concurrent generators, and a combinator-based approach ala QuickCheck. This paper presents the result of

  5. A generalized Jonckheere test against ordered alternatives for repeated measures in randomized blocks.

    Science.gov (United States)

    Zhang, Ying; Cabilio, Paul

    2013-05-10

    Focusing on statistical methods in patient-reported outcomes, we propose and develop a generalized Jonckheere test against ordered alternatives for repeated measures in a randomized block design. We derive its asymptotic null distribution properties and describe methods for estimating the null distribution for testing the hypothesis. We present a numerical example to illustrate the test procedure. Copyright © 2012 John Wiley & Sons, Ltd.

  6. 49 CFR 178.608 - Vibration standard.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Vibration standard. 178.608 Section 178.608... Testing of Non-bulk Packagings and Packages § 178.608 Vibration standard. (a) Each packaging must be capable of withstanding, without rupture or leakage, the vibration test procedure outlined in this section...

  7. The effects of whole-body vibration therapy on bone turnover, muscle strength, motor function, and spasticity in chronic stroke: a randomized controlled trial.

    Science.gov (United States)

    Pang, M Y C; Lau, R W K; Yip, S P

    2013-08-01

    Whole-body vibration (WBV) has been used in older adults to improve bone health and neuromuscular function, and may have potential applications for stroke patients. To investigate the effects of WBV on bone turnover, leg muscle strength, motor function, and spasticity among chronic stroke patients. Randomized controlled trial (RCT). Community. Eighty-two chronic stroke patients. The experimental group underwent exercise training with WBV stimulation for a maximum of 15 minutes, 3 days per week for 8 weeks. The controls received the same exercises without WBV. Participants were evaluated for isokinetic knee muscle strength, serum levels of bone formation and resorption markers, spasticity and motor function of the paretic leg at baseline, immediately after the 8-week training period, and 1-month follow-up. Intention-to-treat analysis revealed no significant changes in levels of bone turnover markers and motor function of the paretic leg over time in both groups. Muscle strength outcomes showed no significant group×time interaction, with similar significant improvements found in both groups. Spasticity of the paretic knee was significantly reduced in the experimental group (P=0.005), but not in controls (P=0.465). No serious adverse events were reported. The WBV protocol used in this study did not induce additional effects on bone turnover, knee muscle strength and paretic leg motor function among chronic stroke patients. WBV may have potential to modulate spasticity, but this requires further investigation. More study on WBV is required before it can be recommended as an adjunct treatment in rehabilitation of chronic stroke patients.

  8. Clinical evaluation of hand-arm-vibration syndrome in shipyard workers: sensitivity and specificity as compared to Stockholm classification and vibrometry testing.

    Science.gov (United States)

    Kent, D C; Allen, R; Bureau, P; Cherniack, M; Hans, J; Robinson, M

    1998-02-01

    The hand-arm-vibration syndrome (HAVS) is a complex entity composed of circulatory, sensory, and motor disturbances, as well as associated musculoskeletal components. This study was performed to find a diagnostic testing modality with sufficient sensitivity, specificity, and predictive value to be utilized as a screening test for this disorder in a working population. A full range of testing modalities was utilized in the shipyard medical department. In addition, a clinical diagnosis of vascular and sensorineural disease was established in the workers by a combination of plethysmography, vibrometry, two point discrimination, and monofilament testing in an independent occupational medicine clinic. No one test modality met the requirements for such a definitive diagnostic test. Rather, a range of modalities was required to reach any acceptable level of predictive value, with sufficient degrees of specificity and sensitivity.

  9. Random Testing and Model Checking: Building a Common Framework for Nondeterministic Exploration

    Science.gov (United States)

    Groce, Alex; Joshi, Rajeev

    2008-01-01

    Two popular forms of dynamic analysis, random testing and explicit-state software model checking, are perhaps best viewed as search strategies for exploring the state spaces introduced by nondeterminism in program inputs. We present an approach that enables this nondeterminism to be expressed in the SPIN model checker's PROMELA language, and then lets users generate either model checkers or random testers from a single harness for a tested C program. Our approach makes it easy to compare model checking and random testing for models with precisely the same input ranges and probabilities and allows us to mix random testing with model checking's exhaustive exploration of non-determinism. The PROMELA language, as intended in its design, serves as a convenient notation for expressing nondeterminism and mixing random choices with nondeterministic choices. We present and discuss a comparison of random testing and model checking. The results derive from using our framework to test a C program with an effectively infinite state space, a module in JPL's next Mars rover mission. More generally, we show how the ability of the SPIN model checker to call C code can be used to extend SPIN's features, and hope to inspire others to use the same methods to implement dynamic analyses that can make use of efficient state storage, matching, and backtracking.

  10. Is two better than one? Muscle vibration plus robotic rehabilitation to improve upper limb spasticity and function: A pilot randomized controlled trial.

    Directory of Open Access Journals (Sweden)

    Rocco Salvatore Calabrò

    Full Text Available Even though robotic rehabilitation is very useful to improve motor function, there is no conclusive evidence on its role in reducing post-stroke spasticity. Focal muscle vibration (MV is instead very useful to reduce segmental spasticity, with a consequent positive effect on motor function. Therefore, it could be possible to strengthen the effects of robotic rehabilitation by coupling MV. To this end, we designed a pilot randomized controlled trial (Clinical Trial NCT03110718 that included twenty patients suffering from unilateral post-stroke upper limb spasticity. Patients underwent 40 daily sessions of Armeo-Power training (1 hour/session, 5 sessions/week, for 8 weeks with or without spastic antagonist MV. They were randomized into two groups of 10 individuals, which received (group-A or not (group-B MV. The intensity of MV, represented by the peak acceleration (a-peak, was calculated by the formula (2πf2A, where f is the frequency of MV and A is the amplitude. Modified Ashworth Scale (MAS, short intracortical inhibition (SICI, and Hmax/Mmax ratio (HMR were the primary outcomes measured before and after (immediately and 4 weeks later the end of the treatment. In all patients of group-A, we observed a greater reduction of MAS (p = 0.007, d = 0.6 and HMR (p<0.001, d = 0.7, and a more evident increase of SICI (p<0.001, d = 0.7 up to 4 weeks after the end of the treatment, as compared to group-B. Likewise, group-A showed a greater function outcome of upper limb (Functional Independence Measure p = 0.1, d = 0.7; Fugl-Meyer Assessment of the Upper Extremity p = 0.007, d = 0.4 up to 4 weeks after the end of the treatment. A significant correlation was found between the degree of MAS reduction and SICI increase in the agonist spastic muscles (p = 0.004. Our data show that this combined rehabilitative approach could be a promising option in improving upper limb spasticity and motor function. We could hypothesize that the greater rehabilitative outcome

  11. Vibrational Diver

    Science.gov (United States)

    Kozlov, Victor; Ivanova, Alevtina; Schipitsyn, Vitalii; Stambouli, Moncef

    2014-10-01

    The paper is concerned with dynamics of light solid in cavity with liquid subjected to rotational vibration in the external force field. New vibrational phenomenon - diving of a light cylinder to the cavity bottom is found. The experimental investigation of a horizontal annulus with a partition has shown that under vibration a light body situated in the upper part of the layer is displaced in a threshold manner some distance away from the boundary. In this case the body executes symmetric tangential oscillations. An increase of the vibration intensity leads to a tangential displacement of the body near the external boundary. This displacement is caused by the tangential component of the vibrational lift force, which appears as soon as the oscillations lose symmetry. In this case the trajectory of the body oscillatory motion has the form of a loop. The tangential lift force makes stable the position of the body on the inclined section of the layer and even in its lower part. A theoretical interpretation has been proposed, which explains stabilization of a quasi-equilibrium state of a light body near the cavity bottom in the framework of vibrational hydromechanics.

  12. Infra-red and vibration tests of hybrid ablative/ceramic matrix technological breadboards for earth re-entry thermal protection systems

    Science.gov (United States)

    Barcena, Jorge; Garmendia, Iñaki; Triantou, Kostoula; Mergia, Konstatina; Perez, Beatriz; Florez, Sonia; Pinaud, Gregory; Bouilly, Jean-Marc; Fischer, Wolfgang P. P.

    2017-05-01

    A new thermal protection system for atmospheric earth re-entry is proposed. This concept combines the advantages of both reusable and ablative materials to establish a new hybrid concept with advanced capabilities. The solution consists of the design and the integration of a dual shield resulting on the overlapping of an external thin ablative layer with a Ceramic Matrix Composite (CMC) thermo-structural core. This low density ablative material covers the relatively small heat peak encountered during re-entry the CMC is not able to bear. On the other hand the big advantage of the CMC based TPS is of great benefit which can deal with the high integral heat for the bigger time period of the re-entry. To verify the solution a whole testing plan is envisaged, which as part of it includes thermal shock test by infra-red heating (heating flux up to 1 MW/m2) and vibration test under launcher conditions (Volna and Ariane 5). Sub-scale tile samples (100×100 mm2) representative of the whole system (dual ablator/ceramic layers, insulation, stand-offs) are specifically designed, assembled and tested (including the integration of thermocouples). Both the thermal and the vibration test are analysed numerically by simulation tools using Finite Element Models. The experimental results are in good agreement with the expected calculated parameters and moreover the solution is qualified according to the specified requirements.

  13. Vibration considerations for cryogenic tanks using glass bubbles insulation

    Science.gov (United States)

    Werlink, Rudy John; Fesmire, James; Sass, Jared P.

    2012-06-01

    The use of glass bubbles as an efficient and practical thermal insulation system hasbeen previously demonstrated in cryogenic storage tanks. One such example is a spherical,vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate hasbeen reduced by approximately 50 percent. Further applications may include non-stationarytanks such as mobile tankers and tanks with extreme duty cycles or exposed to significantvibration environments. Space rocket launch events and mobile tanker life cycles representtwo harsh cases of mechanical vibration exposure. A number of bulk fill insulationmaterials including glass bubbles, perlite powders, and aerogel granules were tested forvibration effects and mechanical behavior using a custom design holding fixture subjectedto random vibration on an Electrodynamic Shaker. The settling effects for mixtures ofinsulation materials were also investigated. The vibration test results and granular particleanalysis are presented with considerations and implications for future cryogenic tankapplications.

  14. Energy Finite Element Analysis for Computing the High Frequency Vibration of the Aluminum Testbed Cylinder and Correlating the Results to Test Data

    Science.gov (United States)

    Vlahopoulos, Nickolas

    2005-01-01

    The Energy Finite Element Analysis (EFEA) is a finite element based computational method for high frequency vibration and acoustic analysis. The EFEA solves with finite elements governing differential equations for energy variables. These equations are developed from wave equations. Recently, an EFEA method for computing high frequency vibration of structures either in vacuum or in contact with a dense fluid has been presented. The presence of fluid loading has been considered through added mass and radiation damping. The EFEA developments were validated by comparing EFEA results to solutions obtained by very dense conventional finite element models and solutions from classical techniques such as statistical energy analysis (SEA) and the modal decomposition method for bodies of revolution. EFEA results have also been compared favorably with test data for the vibration and the radiated noise generated by a large scale submersible vehicle. The primary variable in EFEA is defined as the time averaged over a period and space averaged over a wavelength energy density. A joint matrix computed from the power transmission coefficients is utilized for coupling the energy density variables across any discontinuities, such as change of plate thickness, plate/stiffener junctions etc. When considering the high frequency vibration of a periodically stiffened plate or cylinder, the flexural wavelength is smaller than the interval length between two periodic stiffeners, therefore the stiffener stiffness can not be smeared by computing an equivalent rigidity for the plate or cylinder. The periodic stiffeners must be regarded as coupling components between periodic units. In this paper, Periodic Structure (PS) theory is utilized for computing the coupling joint matrix and for accounting for the periodicity characteristics.

  15. Offering self-administered oral HIV testing to truck drivers in Kenya to increase testing: a randomized controlled trial.

    Science.gov (United States)

    Kelvin, Elizabeth A; George, Gavin; Mwai, Eva; Nyaga, Eston; Mantell, Joanne E; Romo, Matthew L; Odhiambo, Jacob O; Starbuck, Lila; Govender, Kaymarlin

    2018-01-01

    We conducted a randomized controlled trial among 305 truck drivers from two North Star Alliance roadside wellness clinics in Kenya to see if offering HIV testing choices would increase HIV testing uptake. Participants were randomized to be offered (1) a provider-administered rapid blood (finger-prick) HIV test (i.e., standard of care [SOC]) or (2) a Choice between SOC or a self-administered oral rapid HIV test with provider supervision in the clinic. Participants in the Choice arm who refused HIV testing in the clinic were offered a test kit for home use with phone-based posttest counseling. We compared HIV test uptake using the Mantel Haenszel odds ratio (OR) adjusting for clinic. Those in the Choice arm had higher odds of HIV test uptake than those in the SOC arm (OR = 1.5), but the difference was not statistically significant (p = 0.189). When adding the option to take an HIV test kit for home use, the Choice arm had significantly greater odds of testing uptake (OR = 2.8, p = 0.002). Of those in the Choice arm who tested, 26.9% selected the SOC test, 64.6% chose supervised self-testing in the clinic, and 8.5% took a test kit for home use. Participants varied in the HIV test they selected when given choices. Importantly, when participants who refused HIV testing in the clinic were offered a test kit for home use, an additional 8.5% tested. Offering truck drivers a variety of HIV testing choices may increase HIV testing uptake in this key population.

  16. Progress Letter Report on Bending Fatigue Test System Development for Spent Nuclear Fuel Vibration Integrity Study (Out-of-cell fatigue testing development - Task 2.4)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Wang, Hong [ORNL; Cox, Thomas S [ORNL; Baldwin, Charles A [ORNL; Bevard, Bruce Balkcom [ORNL

    2013-08-01

    Vibration integrity of high burn-up spent nuclear fuel in transportation remains to be a critical component of US nuclear waste management system. The structural evaluation of package for spent fuel transportation eventually will need to see if the content or spent fuel is in a subcritical condition. However, a system for testing and characterizing such spent fuel is still lacking mainly due to the complication involved with dealing radioactive specimens in a hot cell environment. Apparently, the current state-of-the-art in spent fuel research and development is quite far away from the delivery of reliable mechanical property data for the assessment of spent fuels in the transport package evaluation. Under the sponsorship of US NRC, ORNL has taken the challenge in developing a robust testing system for spent fuel in hot cell. An extensive literature survey was carried out and unique requirements of such testing system were identified. The U-frame setup has come to the top among various designs examined for reverse bending fatigue test of spent fuel rod. The U-frame has many features that deserve mentioned here: Easy to install spent fuel rod in test; Less linkages than in conventional bending test setup such as three-point or four-point bending; Target the failure mode relevant to the fracture of spent fuel rod in transportation by focusing on pure bending; The continuous calibrations and modifications resulted in the third generation (3G) U-frame testing setup. Rigid arms are split along the LBB axis at rod sample ends. For each arm, this results in a large arm body and an end piece. Mating halves of bushings were modified into two V-shaped surfaces on which linear roller bearings (LRB) are embedded. The rod specimen is installed into the test fixture through opening and closing slide end-pieces. The 3G apparently has addressed major issues of setup identified in the previous stage and been proven to be eligible to be further pursued in this project. On the other

  17. Vibration Durability Testing of Nickel Manganese Cobalt Oxide (NMC) Lithium-Ion 18,650 Battery Cells

    OpenAIRE

    Hooper, James Michael; Marco, James; Chouchelamane, Gael H.; Lyness, Christopher

    2016-01-01

    Electric vehicle (EV) manufacturers are employing cylindrical format cells in the construction of the vehicles’ battery systems. There is evidence to suggest that both the academic and industrial communities have evaluated cell degradation due to vibration and other forms of mechanical loading. The primary motivation is often the need to satisfy the minimum requirements for safety certification. However, there is limited research that quantifies the durability of the battery and in particular...

  18. Comparing entropy with tests for randomness as a measure of complexity in time series

    CERN Document Server

    Gan, Chee Chun

    2015-01-01

    Entropy measures have become increasingly popular as an evaluation metric for complexity in the analysis of time series data, especially in physiology and medicine. Entropy measures the rate of information gain, or degree of regularity in a time series e.g. heartbeat. Ideally, entropy should be able to quantify the complexity of any underlying structure in the series, as well as determine if the variation arises from a random process. Unfortunately current entropy measures mostly are unable to perform the latter differentiation. Thus, a high entropy score indicates a random or chaotic series, whereas a low score indicates a high degree of regularity. This leads to the observation that current entropy measures are equivalent to evaluating how random a series is, or conversely the degree of regularity in a time series. This raises the possibility that existing tests for randomness, such as the runs test or permutation test, may have similar utility in diagnosing certain conditions. This paper compares various t...

  19. Deviations of frequency and the mode of vibration of commercially available whole-body vibration training devices.

    Science.gov (United States)

    Kaeding, T S

    2015-06-01

    Research in the field of whole body vibration (WBV) training and the use of it in practice might be hindered by the fact that WBV training devices generate and transmit frequencies and/or modes of vibration which are different to preset adjustments. This research project shall clarify how exact WBV devices apply the by manufacturer information promised preset frequency and mode of vibration. Nine professional devices for WBV training were tested by means of a tri-axial accelerometer. The accelerations of each device were recorded under different settings with a tri-axial accelerometer. Beneath the measurement of different combinations of preset frequency and amplitude the repeatability across 3 successive measurements with the same preset conditions and one measurement under loaded condition were carried out. With 3 exceptions (both Board 3000 & srt medical PRO) we did not find noteworthy divergences between preset and actual applied frequencies. In these 3 devices we found divergences near -25%. Loading the devices did not affect the applied frequency or mode of vibration. There were no important divergences measurable for the applied frequency and mode of vibration regarding repeatability. The results of our measurements cannot be generalized as we only measured one respectively at most two devices of one model in terms of a random sample. Based on these results we strongly recommend that user in practice and research should analyse their WBV training devices regarding applied frequency and mode of vibration.

  20. Does giving segmental muscle vibration alter the response to botulinum toxin injections in the treatment of spasticity in people with multiple sclerosis? A single-blind randomized controlled trial.

    Science.gov (United States)

    Paoloni, Marco; Giovannelli, Morena; Mangone, Massimiliano; Leonardi, Laura; Tavernese, Emanuela; Di Pangrazio, Elisabetta; Bernetti, Andrea; Santilli, Valter; Pozzilli, Carlo

    2013-09-01

    To determine if segmental muscle vibration and botulinum toxin-A injection, either alone or in combination, reduces spasticity in a sample of patients with multiple sclerosis. Single-blind, randomized controlled trial. Physical medicine and rehabilitation outpatients service. Forty-two patients affected by the secondary progressive form of multiple sclerosis randomized to group A (30 minutes of 120 Hz segmental muscle vibration over the rectus femoris and gastrocnemius medial and lateral, three per week, over a period of four weeks), group B (botulinum toxin in the rectus femoris, gastrocnemius medial and lateral and soleus, and segmental muscle vibration) and group C (botulinum toxin). Modified Ashworth Scale at knee and ankle, and Fatigue Severity Scale. All the measurements were performed at baseline (T0), 10 weeks (T1) and 22 weeks (T2) postallocation. Modified Ashworth Scale at knee and ankle significantly decreased over time (p Fatigue Severity Scale values in groups A and C were significantly higher at T0 [A: 53.6 (2.31); C: 48.5 (2.77)] than at either T1 [A: 48.6 (2.21); p = 0.03; C: 43.5 (3.22); p = 0.03] or T2 [A: 46.7 (2.75); p = 0.02; 42.5 (2.17); p = 0.02], while no differences were detected in group B [T0: 43.4 (3.10); T1: 37.3 (3.15); T2: 39.7 (2.97)]. Segmental muscle vibration and botulinum toxin-A reduces spasticity and improves fatigue in the medium-term follow-up in patients with multiple sclerosis.

  1. A test for stationarity of spatio-temporal random fields on planar and spherical domains

    KAUST Repository

    Jun, Mikyoung

    2012-01-01

    A formal test for weak stationarity of spatial and spatio-temporal random fields is proposed. We consider the cases where the spatial domain is planar or spherical, and we do not require distributional assumptions for the random fields. The method can be applied to univariate or to multivariate random fields. Our test is based on the asymptotic normality of certain statistics that are functions of estimators of covariances at certain spatial and temporal lags under weak stationarity. Simulation results for spatial as well as spatio-temporal cases on the two types of spatial domains are reported. We describe the results of testing the stationarity of Pacific wind data, and of testing the axial symmetry of climate model errors for surface temperature using the NOAA GFDL model outputs and the observations from the Climate Research Unit in East Anglia and the Hadley Centre.

  2. Effect of shelf aging on vibration transmissibility of anti-vibration gloves.

    Science.gov (United States)

    Shibata, Nobuyuki

    2017-10-05

    Anti-vibration gloves have been used in real workplaces to reduce vibration transmitted through hand-held power tools to the hand. Generally materials used for vibration attenuation in gloves are resilient materials composed of certain synthetic and/or composite polymers. The mechanical characteristics of the resilient materials used in anti-vibration gloves are prone to be influenced by environmental conditions such as temperature, humidity, and photo-irradiation, which cause material degradation and aging. This study focused on the influence of shelf aging on the vibration attenuation performance of air-packaged anti-vibration gloves following 2 years of shelf aging. Effects of shelf aging on the vibration attenuation performance of anti-vibration gloves were examined according to the Japan industrial standard JIS T8114 test protocol. The findings indicate that shelf aging induces the reduction of vibration attenuation performance in air-packaged anti-vibration gloves.

  3. Monte Carlo randomization tests for large-scale abundance datasets on the GPU.

    Science.gov (United States)

    Van Hemert, John L; Dickerson, Julie A

    2011-01-01

    Statistical tests are often performed to discover which experimental variables are reacting to specific treatments. Time-series statistical models usually require the researcher to make assumptions with respect to the distribution of measured responses which may not hold. Randomization tests can be applied to data in order to generate null distributions non-parametrically. However, large numbers of randomizations are required for the precise p-values needed to control false discovery rates. When testing tens of thousands of variables (genes, chemical compounds, or otherwise), significant q-value cutoffs can be extremely small (on the order of 10(-5) to 10(-8)). This requires high-precision p-values, which in turn require large numbers of randomizations. The NVIDIA(®) Compute Unified Device Architecture(®) (CUDA(®)) platform for General Programming on the Graphics Processing Unit (GPGPU) was used to implement an application which performs high-precision randomization tests via Monte Carlo sampling for quickly screening custom test statistics for experiments with large numbers of variables, such as microarrays, Next-Generation sequencing read counts, chromatographical signals, or other abundance measurements. The software has been shown to achieve up to more than 12 fold speedup on a Graphics Processing Unit (GPU) when compared to a powerful Central Processing Unit (CPU). The main limitation is concurrent random access of shared memory on the GPU. The software is available from the authors. 2011 Elsevier Ireland Ltd. All rights reserved.

  4. Precision measurements and test of molecular theory in highly-excited vibrational states of H$_2$ $(v=11)$

    CERN Document Server

    Trivikram, T Madhu; Wcisło, P; Ubachs, W; Salumbides, E J

    2016-01-01

    Accurate $EF{}^1\\Sigma^+_g-X{}^1\\Sigma^+_g$ transition energies in molecular hydrogen were determined for transitions originating from levels with highly-excited vibrational quantum number, $v=11$, in the ground electronic state. Doppler-free two-photon spectroscopy was applied on vibrationally excited H$_2^*$, produced via the photodissociation of H$_2$S, yielding transition frequencies with accuracies of $45$ MHz or $0.0015$ cm$^{-1}$. An important improvement is the enhanced detection efficiency by resonant excitation to autoionizing $7p\\pi$ electronic Rydberg states, resulting in narrow transitions due to reduced ac-Stark effects. Using known $EF$ level energies, the level energies of $X(v=11, J=1,3-5)$ states are derived with accuracies of typically 0.002 cm$^{-1}$. These experimental values are in excellent agreement with, and are more accurate than the results obtained from the most advanced ab initio molecular theory calculations including relativistic and QED contributions.

  5. Vibrating minds

    CERN Document Server

    2009-01-01

    Ed Witten is one of the leading scientists in the field of string theory, the theory that describes elementary particles as vibrating strings. This week he leaves CERN after having spent a few months here on sabbatical. His wish is that the LHC will unveil supersymmetry.

  6. Enhancement of rowing performance in athletes after focal muscle vibration therapy

    Directory of Open Access Journals (Sweden)

    Francesca Grasso

    2017-06-01

    Full Text Available Muscle vibration has been reported to induce long lasting effects on proprioception when applied on specific body segment. The aim of this study was to evaluate the effect of focal muscle vibration applied on quadriceps and latissimus dorsi muscles in athletes evaluate during rowing test. Sixteen volunteered national level sculling stroke rowers has been randomized in a study group and in a control group (treated with sham vibration. The overall kinematic consistency, joints angular acceleration patterns and performance test has been used as evaluation. Results showed statistical significant values for angular accelerations at the knee and shoulder joints and significant effect of the time course of the trial. Vibration treatment seems to be an useful proprioceptive stimulation in sport activities to improve muscle control and performance.

  7. Hidden dangers revealed by misdiagnosed diabetic neuropathy: A comparison of simple clinical tests for the screening of vibration perception threshold at primary care level.

    Science.gov (United States)

    Azzopardi, Kurt; Gatt, Alfred; Chockalingam, Nachiappan; Formosa, Cynthia

    2017-10-10

    Diabetic peripheral neuropathy is an important complication and contributes to the morbidity of diabetes mellitus. Evidence indicates early detection of diabetic peripheral neuropathy results in fewer foot ulcers and amputations. The aim of this study was to compare different screening modalities in the detection of diabetic peripheral neuropathy in a primary care setting. A prospective non-experimental comparative multi-centre cross sectional study was conducted in various Primary Health Centres. One hundred participants living with Type 2 diabetes for at least 10 years were recruited using a convenience sampling method. The Vibratip, 128Hz tuning fork and neurothesiometer were compared in the detection of vibration perception. This study showed different results of diabetic peripheral neuropathy screening tests, even in the same group of participants. This study has shown that the percentage of participants who did not perceive vibrations was highest when using the VibraTip (28.5%). This was followed by the neurothesiometer (21%) and the 128Hz tuning fork (12%) (pneuropathy in patients with diabetes is crucial. This study demonstrates that some instruments are more sensitive to vibration perception than others. We recommend that different modalities should be used in patients with diabetes and when results do not concur, further neurological evaluation should be performed. This would significantly reduce the proportion of patients with diabetes who would be falsely identified as having no peripheral neuropathy and subsequently denied the benefit of beneficial and effective secondary risk factor control. Copyright © 2017 Primary Care Diabetes Europe. Published by Elsevier Ltd. All rights reserved.

  8. Testing of hypothesis of two-dimensional random variables independence on the basis of algorithm of pattern recognition

    Science.gov (United States)

    Lapko, A. V.; Lapko, V. A.; Yuronen, E. A.

    2016-11-01

    The new technique of testing of hypothesis of random variables independence is offered. Its basis is made by nonparametric algorithm of pattern recognition. The considered technique doesn't demand sampling of area of values of random variables.

  9. Hardy-Weinberg equilibrium testing of biological ascertainment for Mendelian randomization studies.

    Science.gov (United States)

    Rodriguez, Santiago; Gaunt, Tom R; Day, Ian N M

    2009-02-15

    Mendelian randomization (MR) permits causal inference between exposures and a disease. It can be compared with randomized controlled trials. Whereas in a randomized controlled trial the randomization occurs at entry into the trial, in MR the randomization occurs during gamete formation and conception. Several factors, including time since conception and sampling variation, are relevant to the interpretation of an MR test. Particularly important is consideration of the "missingness" of genotypes that can be originated by chance, genotyping errors, or clinical ascertainment. Testing for Hardy-Weinberg equilibrium (HWE) is a genetic approach that permits evaluation of missingness. In this paper, the authors demonstrate evidence of nonconformity with HWE in real data. They also perform simulations to characterize the sensitivity of HWE tests to missingness. Unresolved missingness could lead to a false rejection of causality in an MR investigation of trait-disease association. These results indicate that large-scale studies, very high quality genotyping data, and detailed knowledge of the life-course genetics of the alleles/genotypes studied will largely mitigate this risk. The authors also present a Web program (http://www.oege.org/software/hwe-mr-calc.shtml) for estimating possible missingness and an approach to evaluating missingness under different genetic models.

  10. The analysis of nonstationary vibration data

    Science.gov (United States)

    Piersol, Allan G.

    1987-01-01

    The general methodology for the analysis of arbitrary nonstationary random data is reviewed. A specific parametric model, called the product model, that has applications to space vehicle launch vibration data analysis is discussed. Illustrations are given using the nonstationary launch vibration data measured on the Space Shuttle orbiter vehicle.

  11. Genetic susceptibility testing and readiness to control weight: Results from a randomized controlled trial

    NARCIS (Netherlands)

    Meisel, S.F.; Beeken, R.J.; Jaarsveld, C.H.M. van; Wardle, J.

    2015-01-01

    OBJECTIVE: To test the hypothesis that adding obesity gene feedback (FTO) to simple weight control advice at a life stage with raised risk of weight gain (university) increases readiness to control weight. METHODS: Individually randomized controlled trial comparing the effect of: (i) simple weight

  12. A Mixture Proportional Hazards Model with Random Effects for Response Times in Tests

    Science.gov (United States)

    Ranger, Jochen; Kuhn, Jörg-Tobias

    2016-01-01

    In this article, a new model for test response times is proposed that combines latent class analysis and the proportional hazards model with random effects in a similar vein as the mixture factor model. The model assumes the existence of different latent classes. In each latent class, the response times are distributed according to a…

  13. Do exchange rates follow random walks? A variance ratio test of the ...

    African Journals Online (AJOL)

    However, emerging markets in sub-Saharan Africa have received little attention in this regard. This study applies Lo and MacKinlay's (1988) conventional variance ... Both types of variance ratio tests reject the random-walk hypothesis over the data span. The implication is that technical and fundamental analysis can help ...

  14. Testing Mediators of Intervention Effects in Randomized Controlled Trials: An Evaluation of Three Depression Prevention Programs

    Science.gov (United States)

    Stice, Eric; Rohde, Paul; Seeley, John R.; Gau, Jeff M.

    2010-01-01

    Objective: Evaluate a new 5-step method for testing mediators hypothesized to account for the effects of depression prevention programs. Method: In this indicated prevention trial, at-risk teens with elevated depressive symptoms were randomized to a group cognitive-behavioral (CB) intervention, group supportive expressive intervention, CB…

  15. A Randomization Test for Controlling Population Stratification in Whole-Genome Association Studies

    OpenAIRE

    Kimmel, Gad; Jordan, Michael I.; Halperin, Eran; Shamir, Ron; Karp, Richard M.

    2007-01-01

    Population stratification can be a serious obstacle in the analysis of genomewide association studies. We propose a method for evaluating the significance of association scores in whole-genome cohorts with stratification. Our approach is a randomization test akin to a standard permutation test. It conditions on the genotype matrix and thus takes into account not only the population structure but also the complex linkage disequilibrium structure of the genome. As we show in simulation experime...

  16. A novel bending fatigue test device based on self-excited vibration principle and its application to superelastic Nitinol microwire study

    Science.gov (United States)

    Leng, Jiaming; Yan, Xiaojun; Zhang, Xiaoyong; Qi, Mingjing; Liu, Zhiwei; Huang, Dawei

    2017-10-01

    Most Nitinol-alloy-based biomedical devices are usually manufactured from straight drawn microwires or microbeams. Fatigue due to cyclic bending is interpreted as the primary failure mechanism in these devices. However, the bending fatigue performance of a Nitinol microwire is rarely studied because of the lack of test devices. Therefore, we firstly establish a bending fatigue test device based on the self-excited vibration principle. Then, we further improve and experimentally verify the device in three aspects to enlarge the strain amplitude: electrode distance optimization, electrode placement angle optimization and local stiffness enhancement. Based on these improvements, the strain amplitude is increased to 6%, successfully meeting the requirements of Nitinol microwire bending fatigue tests. Using the improved test device, a group of superelastic Nitinol (55.8% Ni-44.2% Ti) microwires with a diameter of 50.8 μm are tested. The test results show that the fatigue strain limit for the chosen life (1 × 106 cycles) is around 1.9%, and the inflexion appears at a strain amplitude of 2.3%. SEM observation shows the typical features of low-cycle and high-cycle fatigue on the fracture surfaces.

  17. 78 FR 77196 - Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of...

    Science.gov (United States)

    2013-12-20

    ... testing rate is based on the reported random drug test positive rate for the entire aviation industry. If... TRANSPORTATION Federal Aviation Administration Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of January 1, 2014, Through December 31, 2014 AGENCY: Federal Aviation...

  18. 77 FR 71669 - Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of...

    Science.gov (United States)

    2012-12-03

    ... testing rate is based on the reported random drug test positive rate for the entire aviation industry. If... Federal Aviation Administration Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of January 1, 2013, Through December 31, 2013 AGENCY: Federal Aviation...

  19. 76 FR 74843 - Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of...

    Science.gov (United States)

    2011-12-01

    ... testing rate is based on the reported random drug test positive rate for the entire aviation industry. If... Federal Aviation Administration Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of January 1, 2012, Through December 31, 2012 AGENCY: Federal Aviation...

  20. Stratified exact tests for the weak causal null hypothesis in randomized trials with a binary outcome.

    Science.gov (United States)

    Chiba, Yasutaka

    2017-09-01

    Fisher's exact test is commonly used to compare two groups when the outcome is binary in randomized trials. In the context of causal inference, this test explores the sharp causal null hypothesis (i.e. the causal effect of treatment is the same for all subjects), but not the weak causal null hypothesis (i.e. the causal risks are the same in the two groups). Therefore, in general, rejection of the null hypothesis by Fisher's exact test does not mean that the causal risk difference is not zero. Recently, Chiba (Journal of Biometrics and Biostatistics 2015; 6: 244) developed a new exact test for the weak causal null hypothesis when the outcome is binary in randomized trials; the new test is not based on any large sample theory and does not require any assumption. In this paper, we extend the new test; we create a version of the test applicable to a stratified analysis. The stratified exact test that we propose is general in nature and can be used in several approaches toward the estimation of treatment effects after adjusting for stratification factors. The stratified Fisher's exact test of Jung (Biometrical Journal 2014; 56: 129-140) tests the sharp causal null hypothesis. This test applies a crude estimator of the treatment effect and can be regarded as a special case of our proposed exact test. Our proposed stratified exact test can be straightforwardly extended to analysis of noninferiority trials and to construct the associated confidence interval. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. The effect of a test ordering software intervention on the prescription of unnecessary laboratory tests - a randomized controlled trial.

    Science.gov (United States)

    Martins, Carlos Manuel Silva; da Costa Teixeira, Andreia Sofia; de Azevedo, Luís Filipe Ribeiro; Sá, Luísa Maria Barbosa; Santos, Paulo Alexandre Azevedo Pereira; do Couto, Maria Luciana Gomes Domingues; da Costa Pereira, Altamiro Manuel Rodrigues; Hespanhol, Alberto Augusto Oliveira Pinto; da Costa Santos, Cristina Maria Nogueira

    2017-02-20

    The way software for electronic health records and laboratory tests ordering systems are designed may influence physicians' prescription. A randomised controlled trial was performed to measure the impact of a diagnostic and laboratory tests ordering system software modification. Participants were family physicians working and prescribing diagnostic and laboratory tests. The intervention group had a modified software with a basic shortcut menu changes, where some tests were withdrawn or added, and with the implementation of an evidence-based decision support based on United States Preventive Services Task Force (USPSTF) recommendations. This intervention group was compared with usual software (control group). The outcomes were the number of tests prescribed from those: withdrawn from the basic menu; added to the basic menu; marked with green dots (USPSTF's grade A and B); and marked with red dots (USPSTF's grade D). Comparing the monthly average number of tests prescribed before and after the software modification, from those tests that were withdrawn from the basic menu, the control group prescribed 33.8 tests per 100 consultations before and 30.8 after (p = 0075); the intervention group prescribed 31.3 before and 13.9 after (p menu, the intervention group prescribed a monthly average of 14.0 vs. 29.3 tests per 100 consultations in the control group (p menu of the diagnosis and laboratory tests ordering system had a significant impact and reduced unnecessary prescription of tests. The fact that it was not possible to perform the randomization at the family physicians' level, but only of the computer servers is a limitation of our study. Future research should assess the impact of different tests ordering systems during longer periods. ISRCTN45427977 , May 1st 2014 (retrospectively registered).

  2. Experimental analysis of thread movement in bolted connections due to vibrations

    Science.gov (United States)

    Ramsey, G. ED; Jenkins, Robert C.

    1995-01-01

    This is the final report of research project NAS8-39131 #33 sponsored by NASA's George C. Marshall Space Flight Center (MSFC) and carried out by the Civil Engineering Department of Auburn University (Auburn, Alabama) and personnel of MSFC. The objective of this study was to identify the main design parameters contributing to the loosening of bolts due to vibration and to identify their relative importance and degree of contribution to bolt loosening. Vibration testing was conducted on a shaketable with a controlled-random input in the dynamic testing laboratory of the Structural Test Division of MSFC. Test specimens which contained one test bolt were vibrated for a fixed amount of time and a percentage of pre-load loss was measured. Each specimen tested implemented some combination of eleven design parameters as dictated by the design of experiment methodology employed. The eleven design parameters were: bolt size (diameter), lubrication on bolt, hole tolerance, initial pre-load, nut locking device, grip length, thread pitch, lubrication between mating materials, class of fit, joint configuration, and mass of configuration. These parameters were chosen for this experiment because they are believed to be the design parameters having the greatest impact on bolt loosening. Two values of each design parameter were used and each combination of parameters tested was subjected to two different directions of vibration and two different g-levels of vibration. One replication was made for each test to gain some indication of experimental error and repeatability and to give some degree of statistical credibility to the data, resulting in a total of 96 tests being performed. The results of the investigation indicated that nut locking devices, joint configuration, fastener size, and mass of configuration were significant in bolt loosening due to vibration. The results of this test can be utilized to further research the complex problem of bolt loosening due to vibration.

  3. Blade Vibration Measurement System

    Science.gov (United States)

    Platt, Michael J.

    2014-01-01

    The Phase I project successfully demonstrated that an advanced noncontacting stress measurement system (NSMS) could improve classification of blade vibration response in terms of mistuning and closely spaced modes. The Phase II work confirmed the microwave sensor design process, modified the sensor so it is compatible as an upgrade to existing NSMS, and improved and finalized the NSMS software. The result will be stand-alone radar/tip timing radar signal conditioning for current conventional NSMS users (as an upgrade) and new users. The hybrid system will use frequency data and relative mode vibration levels from the radar sensor to provide substantially superior capabilities over current blade-vibration measurement technology. This frequency data, coupled with a reduced number of tip timing probes, will result in a system capable of detecting complex blade vibrations that would confound traditional NSMS systems. The hardware and software package was validated on a compressor rig at Mechanical Solutions, Inc. (MSI). Finally, the hybrid radar/tip timing NSMS software package and associated sensor hardware will be installed for use in the NASA Glenn spin pit test facility.

  4. Statistical auditing and randomness test of lotto k/N-type games

    Science.gov (United States)

    Coronel-Brizio, H. F.; Hernández-Montoya, A. R.; Rapallo, F.; Scalas, E.

    2008-11-01

    One of the most popular lottery games worldwide is the so-called “lotto k/N”. It considers N numbers 1,2,…,N from which k are drawn randomly, without replacement. A player selects k or more numbers and the first prize is shared amongst those players whose selected numbers match all of the k randomly drawn. Exact rules may vary in different countries. In this paper, mean values and covariances for the random variables representing the numbers drawn from this kind of game are presented, with the aim of using them to audit statistically the consistency of a given sample of historical results with theoretical values coming from a hypergeometric statistical model. The method can be adapted to test pseudorandom number generators.

  5. CM-2 Environmental/Modal Testing of SPACEHAB Racks

    Science.gov (United States)

    McNelis, Mark E.; Goodnight, Thomas W.

    2001-01-01

    Combined environmental/modal vibration testing has been implemented at the NASA Glenn Research Center's Structural Dynamics Laboratory. The benefits of combined vibration testing are that it facilitates test article modal characterization and vibration qualification testing. The Combustion Module-2 (CM-2) is a space experiment that will launch on shuttle mission STS-107 in the SPACEHAB Research Double Module. The CM-2 flight hardware is integrated into a SPACEHAB single and double rack. CM-2 rack-level combined vibration testing was recently completed on a shaker table to characterize the structure's modal response and verify the random vibration response. Control accelerometers and limit force gauges, located between the fixture and rack interface, were used to verify the input excitation. Results of the testing were used to verify the loads and environments for flight on the shuttles.

  6. Analisis Teoritis dan Empiris Uji Craps dari Diehard Battery of Randomness Test untuk Pengujian Pembangkit Bilangan Acaksemu

    Directory of Open Access Journals (Sweden)

    Sari Agustini Hafman

    2013-05-01

    Full Text Available According to Kerchoffs (1883, the security system should only rely on cryptographic keys which is used in that system. Generally, the key sequences are generated by a Pseudo Random Number Generator (PRNG or Random Number Generator (RNG. There are three types of randomness sequences that generated by the RNG and PRNG i.e. pseudorandom sequence, cryptographically secure pseudorandom sequences, and real random sequences. Several statistical tests, including diehard battery of tests of randomness, is used to check the type of randomness sequences that generated by PRNG or RNG. Due to its purpose, the principle on taking the testing parameters and the test statistic are associated with the validity of the conclusion produced by a statistical test, then the theoretical analysis is performed by applying a variety of statistical theory to evaluate craps test, one of the test included in the diehard battery of randomness tests. Craps test, inspired by craps game, aims to examine whether a PRNG produces an independent and identically distributed (iid pseudorandom sequences. To demonstrate the process to produce a test statistics equation and to show how craps games applied on that test, will be carried out theoretical analysis by applying a variety of statistical theory. Furthermore, empirical observations will be done by applying craps test on a PRNG in order to check the test effectiveness in detecting the distribution and independency of sequences which produced by PRNG

  7. Characterization of Electron Microscopes with Binary Pseudo-random Multilayer Test Samples

    Energy Technology Data Exchange (ETDEWEB)

    V Yashchuk; R Conley; E Anderson; S Barber; N Bouet; W McKinney; P Takacs; D Voronov

    2011-12-31

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested [1] and [2] and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi2/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  8. Characterization of electron microscopes with binary pseudo-random multilayer test samples

    Energy Technology Data Exchange (ETDEWEB)

    Yashchuk, Valeriy V., E-mail: VVYashchuk@lbl.gov [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Conley, Raymond [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States); Anderson, Erik H. [Center for X-ray Optics, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Barber, Samuel K. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Bouet, Nathalie [NSLS-II, Brookhaven National Laboratory, Upton, NY 11973 (United States); McKinney, Wayne R. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Takacs, Peter Z. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Voronov, Dmitriy L. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)

    2011-09-01

    Verification of the reliability of metrology data from high quality X-ray optics requires that adequate methods for test and calibration of the instruments be developed. For such verification for optical surface profilometers in the spatial frequency domain, a modulation transfer function (MTF) calibration method based on binary pseudo-random (BPR) gratings and arrays has been suggested and proven to be an effective calibration method for a number of interferometric microscopes, a phase shifting Fizeau interferometer, and a scatterometer [5]. Here we describe the details of development of binary pseudo-random multilayer (BPRML) test samples suitable for characterization of scanning (SEM) and transmission (TEM) electron microscopes. We discuss the results of TEM measurements with the BPRML test samples fabricated from a WiSi{sub 2}/Si multilayer coating with pseudo-randomly distributed layers. In particular, we demonstrate that significant information about the metrological reliability of the TEM measurements can be extracted even when the fundamental frequency of the BPRML sample is smaller than the Nyquist frequency of the measurements. The measurements demonstrate a number of problems related to the interpretation of the SEM and TEM data. Note that similar BPRML test samples can be used to characterize X-ray microscopes. Corresponding work with X-ray microscopes is in progress.

  9. A Bayesian sequential design with adaptive randomization for 2-sided hypothesis test.

    Science.gov (United States)

    Yu, Qingzhao; Zhu, Lin; Zhu, Han

    2017-11-01

    Bayesian sequential and adaptive randomization designs are gaining popularity in clinical trials thanks to their potentials to reduce the number of required participants and save resources. We propose a Bayesian sequential design with adaptive randomization rates so as to more efficiently attribute newly recruited patients to different treatment arms. In this paper, we consider 2-arm clinical trials. Patients are allocated to the 2 arms with a randomization rate to achieve minimum variance for the test statistic. Algorithms are presented to calculate the optimal randomization rate, critical values, and power for the proposed design. Sensitivity analysis is implemented to check the influence on design by changing the prior distributions. Simulation studies are applied to compare the proposed method and traditional methods in terms of power and actual sample sizes. Simulations show that, when total sample size is fixed, the proposed design can obtain greater power and/or cost smaller actual sample size than the traditional Bayesian sequential design. Finally, we apply the proposed method to a real data set and compare the results with the Bayesian sequential design without adaptive randomization in terms of sample sizes. The proposed method can further reduce required sample size. Copyright © 2017 John Wiley & Sons, Ltd.

  10. Crowdsourcing HIV Test Promotion Videos: A Noninferiority Randomized Controlled Trial in China.

    Science.gov (United States)

    Tang, Weiming; Han, Larry; Best, John; Zhang, Ye; Mollan, Katie; Kim, Julie; Liu, Fengying; Hudgens, Michael; Bayus, Barry; Terris-Prestholt, Fern; Galler, Sam; Yang, Ligang; Peeling, Rosanna; Volberding, Paul; Ma, Baoli; Xu, Huifang; Yang, Bin; Huang, Shujie; Fenton, Kevin; Wei, Chongyi; Tucker, Joseph D

    2016-06-01

    Crowdsourcing, the process of shifting individual tasks to a large group, may enhance human immunodeficiency virus (HIV) testing interventions. We conducted a noninferiority, randomized controlled trial to compare first-time HIV testing rates among men who have sex with men (MSM) and transgender individuals who received a crowdsourced or a health marketing HIV test promotion video. Seven hundred twenty-one MSM and transgender participants (≥16 years old, never before tested for HIV) were recruited through 3 Chinese MSM Web portals and randomly assigned to 1 of 2 videos. The crowdsourced video was developed using an open contest and formal transparent judging while the evidence-based health marketing video was designed by experts. Study objectives were to measure HIV test uptake within 3 weeks of watching either HIV test promotion video and cost per new HIV test and diagnosis. Overall, 624 of 721 (87%) participants from 31 provinces in 217 Chinese cities completed the study. HIV test uptake was similar between the crowdsourced arm (37% [114/307]) and the health marketing arm (35% [111/317]). The estimated difference between the interventions was 2.1% (95% confidence interval, -5.4% to 9.7%). Among those tested, 31% (69/225) reported a new HIV diagnosis. The crowdsourced intervention cost substantially less than the health marketing intervention per first-time HIV test (US$131 vs US$238 per person) and per new HIV diagnosis (US$415 vs US$799 per person). Our nationwide study demonstrates that crowdsourcing may be an effective tool for improving HIV testing messaging campaigns and could increase community engagement in health campaigns. NCT02248558. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  11. Adaptive testing for association between two random vectors in moderate to high dimensions.

    Science.gov (United States)

    Xu, Zhiyuan; Xu, Gongjun; Pan, Wei

    2017-11-01

    Testing for association between two random vectors is a common and important task in many fields, however, existing tests, such as Escoufier's RV test, are suitable only for low-dimensional data, not for high-dimensional data. In moderate to high dimensions, it is necessary to consider sparse signals, which are often expected with only a few, but not many, variables associated with each other. We generalize the RV test to moderate-to-high dimensions. The key idea is to data adaptively weight each variable pair based on its empirical association. As the consequence, the proposed test is adaptive, alleviating the effects of noise accumulation in high-dimensional data, and thus maintaining the power for both dense and sparse alternative hypotheses. We show the connections between the proposed test with several existing tests, such as a generalized estimating equations-based adaptive test, multivariate kernel machine regression (KMR), and kernel distance methods. Furthermore, we modify the proposed adaptive test so that it can be powerful for nonlinear or nonmonotonic associations. We use both real data and simulated data to demonstrate the advantages and usefulness of the proposed new test. The new test is freely available in R package aSPC on CRAN at https://cran.r-project.org/web/packages/aSPC/index.html and https://github.com/jasonzyx/aSPC. © 2017 WILEY PERIODICALS, INC.

  12. Dynamic Testing: Toward a Multiple Exciter Test

    Science.gov (United States)

    2015-04-01

    complex electronics and munitions that are more susceptible to fatigue failure increased the potential for vibration to cause catastrophic failures... fatigue equiva- lent laboratory vibration specifications based on measured field data were also advancing. This led to the inclusion of the first fatigue ...critical vibration testing element. The field vibration environment may be described as the simultaneous vibration in three translational and three

  13. Vibrational Damping of Composite Materials

    OpenAIRE

    Biggerstaff, Janet M.

    2006-01-01

    The purpose of this research was to develop new methods of vibrational damping in polymeric composite materials along with expanding the knowledge of currently used vibrational damping methods. A new barrier layer technique that dramatically increased damping in viscoelastic damping materials that interacted with the composite resin was created. A method for testing the shear strength of damping materials cocured in composites was developed. Directional damping materials, where the loss facto...

  14. The effects of pre-exercise vibration stimulation on the exercise-induced muscle damage.

    Science.gov (United States)

    Kim, Ji-Yun; Kang, Da-Haeng; Lee, Joon-Hee; O, Se-Min; Jeon, Jae-Keun

    2017-01-01

    [Purpose] To investigate the effects of pre-induced muscle damage vibration stimulation on the pressure-pain threshold and muscle-fatigue-related metabolites of exercise-induced muscle damage. [Subjects and Methods] Thirty healthy, adult male subjects were randomly assigned to the pre-induced muscle damage vibration stimulation group, post-induced muscle damage vibration stimulation group, or control group (n=10 per group). To investigate the effects of pre-induced muscle damage vibration stimulation, changes in the pressure-pain threshold (lb), creatine kinase level (U/L), and lactate dehydrogenase level (U/L) were measured and analyzed at baseline and at 24 hours, 48 hours, and 72 hours after exercise. [Results] The pressure-pain thresholds and concentrations of creatine kinase and lactate dehydrogenase varied significantly in each group and during each measurement period. There were interactions between the measurement periods and groups, and results of the post-hoc test showed that the pre-induced muscle damage vibration stimulation group had the highest efficacy among the groups. [Conclusion] Pre-induced muscle damage vibration stimulation is more effective than post-induced muscle damage vibration stimulation for preventing muscle damage.

  15. Outcomes of a prospective trial of student-athlete drug testing: the Student Athlete Testing Using Random Notification (SATURN) study.

    Science.gov (United States)

    Goldberg, Linn; Elliot, Diane L; MacKinnon, David P; Moe, Esther L; Kuehl, Kerry S; Yoon, Myeongsun; Taylor, Aaron; Williams, Jason

    2007-11-01

    To assess the effects of random drug and alcohol testing (DAT) among high school athletes. This was a 2-year prospective randomized controlled study of a single cohort among five intervention high schools with a DAT policy and six schools with a deferred policy, serially assessed by voluntary, confidential questionnaires. DAT school athletes were at risk for random testing during the full academic year. Positive test results were reported to parents or guardians, with mandatory counseling. Indices of illicit drug use, with and without alcohol use, were assessed at the beginning and end of each school year for the past month and prior year. Potential mediating variables were evaluated. Student-athletes from intervention and control schools did not differ in past 1-month use of illicit drug or a combination of drug and alcohol use at any of the four follow-up periods. At the end of the initial school year and after 2 full school years, student-athletes at DAT schools reported less drug use during the past year (p < .01) compared to athletes at the deferred policy schools. Combining past year drug and alcohol use together, student-athletes at DAT schools reported less use at the second and third follow-up assessments (p < .05). Paradoxically, DAT athletes across all assessments reported less athletic competence (p < .001), less belief authorities were opposed to drug use (p < .01), and indicated greater risk-taking (p < .05). At the final assessment, DAT athletes believed less in testing benefits (p < .05) and less that testing was a reason not to use drugs (p < .01). No DAT deterrent effects were evident for past month use during any of four follow-up periods. Prior-year drug use was reduced in two of four follow-up self-reports, and a combination of drug and alcohol use was reduced at two assessments as well. Overall, drug testing was accompanied by an increase in some risk factors for future substance use. More research is needed before DAT is considered an

  16. Randomized Test of an Implementation Intention-Based Tool to Reduce Stress-Induced Eating

    OpenAIRE

    O'Connor, DB; Armitage, CJ; Ferguson, E.

    2015-01-01

    Background: Stress may indirectly contribute to disease (e.g., cardiovascular disease, cancer by producing deleterious changes to diet. Purpose: To test effectiveness of a stress management support (SMS) tool to reduce stress-related unhealthy snacking and to promote stress-related healthy snacking. Methods: Participants were randomized to complete a SMS tool with instruction to link stressful situations with healthy snack alternatives (experimental) or a SMS tool without a linking instructio...

  17. A novel vibration sensor based on phase grating interferometry

    Science.gov (United States)

    Li, Qian; Liu, Xiaojun; Zhao, Li; Lei, Zili; Lu, Zhen; Guo, Lei

    2017-05-01

    Vibration sensors with high accuracy and reliability are needed urgently for vibration measurement. In this paper a vibration sensor with nanometer resolution is developed. This sensor is based on the principle of phase grating interference for displacement measurement and spatial polarization phase-shift interference technology, and photoelectric counting and A/D signal subdivision are adopted for vibration data output. A vibration measurement system consisting of vibration actuator and displacement adjusting device has been designed to test the vibration sensor. The high resolution and high reliability of the sensor are verified through a series of comparison experiments with Doppler interferometer.

  18. 75 FR 76069 - Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of...

    Science.gov (United States)

    2010-12-07

    ... aviation industry. If the reported random drug test positive rate is less than 1.00%, the Administrator may... Federal Aviation Administration Random Drug and Alcohol Testing Percentage Rates of Covered Aviation Employees for the Period of January 1, 2011, Through December 31, 2011 AGENCY: Federal Aviation...

  19. A randomization test for controlling population stratification in whole-genome association studies.

    Science.gov (United States)

    Kimmel, Gad; Jordan, Michael I; Halperin, Eran; Shamir, Ron; Karp, Richard M

    2007-11-01

    Population stratification can be a serious obstacle in the analysis of genomewide association studies. We propose a method for evaluating the significance of association scores in whole-genome cohorts with stratification. Our approach is a randomization test akin to a standard permutation test. It conditions on the genotype matrix and thus takes into account not only the population structure but also the complex linkage disequilibrium structure of the genome. As we show in simulation experiments, our method achieves higher power and significantly better control over false-positive rates than do existing methods. In addition, it can be easily applied to whole-genome association studies.

  20. Laser geodynamic satellite thermal/optical/vibrational analyses and testing, volume 2, book 1 technical report. [retroreflector performance

    Science.gov (United States)

    1975-01-01

    The results are presented of a retroreflector performance improvement program. The following areas of the program are discussed: retroreflector dimensional verification, initial optical performance analysis, LAGEOS test retroreflector rework, final optical performance analysis, optical performance tests, evaluations and conclusions, and laser wavelength evaluation and dihedral angle selection. Data tables, diagrams, graphs, and photographs are included.

  1. Tissue vibration in prolonged running.

    Science.gov (United States)

    Friesenbichler, Bernd; Stirling, Lisa M; Federolf, Peter; Nigg, Benno M

    2011-01-04

    The impact force in heel-toe running initiates vibrations of soft-tissue compartments of the leg that are heavily dampened by muscle activity. This study investigated if the damping and frequency of these soft-tissue vibrations are affected by fatigue, which was categorized by the time into an exhaustive exercise. The hypotheses were tested that (H1) the vibration intensity of the triceps surae increases with increasing fatigue and (H2) the vibration frequency of the triceps surae decreases with increasing fatigue. Tissue vibrations of the triceps surae were measured with tri-axial accelerometers in 10 subjects during a run towards exhaustion. The frequency content was quantified with power spectra and wavelet analysis. Maxima of local vibration intensities were compared between the non-fatigued and fatigued states of all subjects. In axial (i.e. parallel to the tibia) and medio-lateral direction, most local maxima increased with fatigue (supporting the first hypothesis). In anterior-posterior direction no systematic changes were found. Vibration frequency was minimally affected by fatigue and frequency changes did not occur systematically, which requires the rejection of the second hypothesis. Relative to heel-strike, the maximum vibration intensity occurred significantly later in the fatigued condition in all three directions. With fatigue, the soft tissue of the triceps surae oscillated for an extended duration at increased vibration magnitudes, possibly due to the effects of fatigue on type II muscle fibers. Thus, the protective mechanism of muscle tuning seems to be reduced in a fatigued muscle and the risk of potential harm to the tissue may increase. Copyright © 2010 Elsevier Ltd. All rights reserved.

  2. Effect of acute and chronic whole-body vibration exercise on serum insulin-like growth factor-1 levels in women with fibromyalgia.

    Science.gov (United States)

    Alentorn-Geli, Eduard; Moras, Gerard; Padilla, Jaume; Fernández-Solà, Joaquim; Bennett, Robert M; Lázaro-Haro, Cristina; Pons, Sebastià

    2009-05-01

    The purpose of this study was to investigate the effect of acute and chronic whole-body vibration exercise on serum insulin-like growth factor-1 (IGF-1) levels in women with fibromyalgia. A randomized controlled two-factor mixed experimental design was used. Twenty-four women with fibromyalgia (age +/- standard error of the mean, 54.95 +/- 2.03) were randomized into the vibration group or the control group. The vibration group underwent a protocol of static and dynamic tasks with whole-body vibration exercise twice a week for a total of six weeks, whereas the control group performed the same protocol without vibratory stimulus. Both groups continued their usual pharmacological treatment. Serum IGF-1 levels were determined using enzyme-linked immunosorbent assay (ELISA). To test the effects of long-term whole-body vibration exercise, serum IGF-1 measurements were taken at baseline and at weeks 1, 3, and 6 of the intervention. To test the short-term effects, at week 1, serum IGF-1 measurements were taken before and immediately following a session of whole-body vibration exercise. Treatment adherence was 93% in the vibration group and 92% in the control group. None of the subjects dropped out of the study. There was an absence of change in IGF-1 at week 1 and week 6 of whole-body vibration exercise. Results show no change in serum IGF-1 levels in women with fibromyalgia undergoing whole-body vibration exercise. Although high-intensity exercise and whole-body vibration exercise have been shown to increase serum IGF-1 in healthy individuals, the effectiveness of whole-body vibration exercise as a strategy to produce improvements in serum IGF-1 levels in women with fibromyalgia could not be demonstrated.

  3. Theory of vibration protection

    CERN Document Server

    Karnovsky, Igor A

    2016-01-01

    This text is an advancement of the theory of vibration protection of mechanical systems with lumped and distributed parameters. The book offers various concepts and methods of solving vibration protection problems, discusses the advantages and disadvantages of different methods, and the fields of their effective applications. Fundamental approaches of vibration protection, which are considered in this book, are the passive, parametric and optimal active vibration protection. The passive vibration protection is based on vibration isolation, vibration damping and dynamic absorbers. Parametric vibration protection theory is based on the Shchipanov-Luzin invariance principle. Optimal active vibration protection theory is based on the Pontryagin principle and the Krein moment method. The book also contains special topics such as suppression of vibrations at the source of their occurrence and the harmful influence of vibrations on humans. Numerous examples, which illustrate the theoretical ideas of each chapter, ar...

  4. Individual Optimal Frequency in Whole-Body Vibration: Effect of Protocol, Joint Angle, and Fatiguing Exercise.

    Science.gov (United States)

    Carlucci, Flaminia; Felici, Francesco; Piccinini, Alberto; Haxhi, Jonida; Sacchetti, Massimo

    2016-12-01

    Carlucci, F, Felici, F, Piccinini, A, Haxhi, J, and Sacchetti, M. Individual optimal frequency in whole-body vibration: effect of protocol, joint angle, and fatiguing exercise. J Strength Cond Res 30(12): 3503-3511, 2016-Recent studies have shown the importance of individualizing the vibration intervention to produce greater effects on the neuromuscular system in less time. The purpose of this study was to assess the individual optimal vibration frequency (OVF) corresponding to the highest muscle activation (RMSmax) during vibration at different frequencies, comparing different protocols. Twenty-nine university students underwent 3 continuous (C) and 2 random (R) different vibrating protocols, maintaining a squat position on a vibration platform. The C protocol lasted 50 seconds and involved the succession of ascending frequencies from 20 to 55 Hz, every 5 seconds. The same protocol was performed twice, having the knee angle at 120° (C) and 90° (C90), to assess the effect of joint angle and after a fatiguing squatting exercise (CF) to evaluate the influence of fatigue on OVF assessment. In the random protocols, vibration time was 20 seconds with a 2-minute (R2) and a 4-minute (R4) pauses between tested frequencies. Muscle activation and OVF values did not differ significantly in the C, R2, and R4 protocols. RMSmax was higher in C90 (p fatiguing exercise had no effect on OVF. In conclusion, the shorter C protocol produced similar myoelectrical activity in the R2 and the R4 protocols, and therefore, it could be equally valid in identifying the OVF with considerable time efficiency. Knee joint angle and fatiguing exercise had an effect on surface electromyography response during vibration but did not affect OVF identification significantly.

  5. Quantitative urine confirmatory testing for synthetic cannabinoids in randomly collected urine specimens.

    Science.gov (United States)

    Castaneto, Marisol S; Scheidweiler, Karl B; Gandhi, Adarsh; Wohlfarth, Ariane; Klette, Kevin L; Martin, Thomas M; Huestis, Marilyn A

    2015-06-01

    Synthetic cannabinoid intake is an ongoing health issue worldwide, with new compounds continually emerging, making drug testing complex. Parent synthetic cannabinoids are rarely detected in urine, the most common matrix employed in workplace drug testing. Optimal identification of synthetic cannabinoid markers in authentic urine specimens and correlation of metabolite concentrations and toxicities would improve synthetic cannabinoid result interpretation. We screened 20 017 randomly collected US military urine specimens between July 2011 and June 2012 with a synthetic cannabinoid immunoassay yielding 1432 presumptive positive specimens. We analyzed all presumptive positive and 1069 negative specimens with our qualitative synthetic cannabinoid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method, which confirmed 290 positive specimens. All 290 positive and 487 randomly selected negative specimens were quantified with the most comprehensive urine quantitative LC-MS/MS method published to date; 290 specimens confirmed positive for 22 metabolites from 11 parent synthetic cannabinoids. The five most predominant metabolites were JWH-018 pentanoic acid (93%), JWH-N-hydroxypentyl (84%), AM2201 N-hydroxypentyl (69%), JWH-073 butanoic acid (69%), and JWH-122 N-hydroxypentyl (45%) with 11.1 (0.1-2,434), 5.1 (0.1-1,239), 2.0 (0.1-321), 1.1 (0.1-48.6), and 1.1 (0.1-250) µg/L median (range) concentrations, respectively. Alkyl hydroxy and carboxy metabolites provided suitable biomarkers for 11 parent synthetic cannabinoids; although hydroxyindoles were also observed. This is by far the largest data set of synthetic cannabinoid metabolites urine concentrations from randomly collected workplace drug testing specimens rather than acute intoxications or driving under the influence of drugs. These data improve the interpretation of synthetic cannabinoid urine test results and suggest suitable urine markers of synthetic cannabinoid intake. This article is a U

  6. Scanning slit for HIE-ISOLDE: vibrations test (linear motion actuator from UHV design, MAXON brushless motor, speed = 10 mm/s)

    CERN Document Server

    Bravin, E; Sosa, A

    2014-01-01

    This report summarizes the results of a series of tests performed on the prototype HIE-ISOLDE diagnostic box (HIE-DB) regarding the vibrations and drifts in the transverse position of the scanning blade while moving in and out of beam path in the HIE-ISOLDE short box prototype. To monitor the transverse position of the blade, a series of 0.1 mm diameter holes were drilled on it and their positions were tracked with an optical system. The linear motion actuator was acquired from UHV design (model LSM38-150-SS), and it was adapted to be driven by a brushless EC motor from MAXON. The speed of the scanning blade during the tests was 10 mm/s. The transverse movement of the slit in the direction perpendicular to the movement was lower than 40 m, and is dominated by the displacement of the contact point of the applied force on the lead-screw. An offset on the slit position was observed while changing the direction of movement of the blade, its amplitude being of the order of 30 m. The amplitudes of the displacements...

  7. Scanning slit for HIE-ISOLDE: vibrational test (linear motion actuator from UHV design, speed = 2.5 mm/s)

    CERN Document Server

    Bravin, E; Sosa, A

    2014-01-01

    This report summarizes the results of a series of tests performed on the prototype HIE-ISOLDE diagnostic box (HIE-DB) regarding the vibrations and drifts in the transverse position of the scanning blade while moving inside or outside the box. To monitor the transverse position of the blade, a series of 0.1 mm diameter holes were drilled on it and their positions were tracked with an optical system. The linear motion actuator was acquired from UHV design (model LSM38-150-SS), is driven by a stepper motor and has all the guiding mechanisms outside vacuum. The maximum speed of the scanning blade during the tests was 2.5 mm/s. The transverse movement of the slit in the direction perpendicular to the movement was lower than 50 m, and is dominated by the displacement of the contact point of the applied force on the lead-screw. An offset on the slit position was observed while changing the direction of movement of the blade, its amplitude being of the order of 30 m. The amplitudes of the displacements of the transve...

  8. Random Gap Detection Test (RGDT) performance of individuals with central auditory processing disorders from 5 to 25 years of age.

    Science.gov (United States)

    Dias, Karin Ziliotto; Jutras, Benoît; Acrani, Isabela Olszanski; Pereira, Liliane Desgualdo

    2012-02-01

    The aim of the present study was to assess the auditory temporal resolution ability in individuals with central auditory processing disorders, to examine the maturation effect and to investigate the relationship between the performance on a temporal resolution test with the performance on other central auditory tests. Participants were divided in two groups: 131 with Central Auditory Processing Disorder and 94 with normal auditory processing. They had pure-tone air-conduction thresholds no poorer than 15 dB HL bilaterally, normal admittance measures and presence of acoustic reflexes. Also, they were assessed with a central auditory test battery. Participants who failed at least one or more tests were included in the Central Auditory Processing Disorder group and those in the control group obtained normal performance on all tests. Following the auditory processing assessment, the Random Gap Detection Test was administered to the participants. A three-way ANOVA was performed. Correlation analyses were also done between the four Random Gap Detection Test subtests data as well as between Random Gap Detection Test data and the other auditory processing test results. There was a significant difference between the age-group performances in children with and without Central Auditory Processing Disorder. Also, 48% of children with Central Auditory Processing Disorder failed the Random Gap Detection Test and the percentage decreased as a function of age. The highest percentage (86%) was found in the 5-6 year-old children. Furthermore, results revealed a strong significant correlation between the four Random Gap Detection Test subtests. There was a modest correlation between the Random Gap Detection Test results and the dichotic listening tests. No significant correlation was observed between the Random Gap Detection Test data and the results of the other tests in the battery. Random Gap Detection Test should not be administered to children younger than 7 years old because

  9. The Shock and Vibration Bulletin. Part 2. Opening Session, Panel Session, Shock Testing and Analysis, Fluid-structure Topics

    Science.gov (United States)

    1976-08-01

    they were to try to get tions, which we have seen in social problems in 20 to 40 thousand hours of MTBF all the money the last few years. I hope there...Mt, o However, the composite bladder had developed-z (1 1l $ X/.- numerous blisters on the surface. Post-test S.-,d , etica ,r., examination of this

  10. Patterns of Cancer Genetic Testing: A Randomized Survey of Oregon Clinicians

    Directory of Open Access Journals (Sweden)

    Summer L. Cox

    2012-01-01

    Full Text Available Introduction. Appropriate use of genetic tests for population-based cancer screening, diagnosis of inherited cancers, and guidance of cancer treatment can improve health outcomes. We investigated clinicians’ use and knowledge of eight breast, ovarian, and colorectal cancer genetic tests. Methods. We conducted a randomized survey of 2,191 Oregon providers, asking about their experience with fecal DNA, OncoVue, BRCA, MMR, CYP2D6, tumor gene expression profiling, UGT1A1, and KRAS. Results. Clinicians reported low confidence in their knowledge of medical genetics; most confident were OB-GYNs and specialists. Clinicians were more likely to have ordered/recommended BRCA and MMR than the other tests, and OB-GYNs were twice as likely to have ordered/recommended BRCA testing than primary care providers. Less than 10% of providers ordered/recommended OncoVue, fecal DNA, CYP2D6, or UGT1A1; less than 30% ordered/recommended tumor gene expression profiles or KRAS. The most common reason for not ordering/recommending these tests was lack of familiarity. Conclusions. Use of appropriate, evidence-based testing can help reduce incidence and mortality of certain cancers, but these tests need to be better integrated into clinical practice. Continued evaluation of emerging technologies, dissemination of findings, and an increase in provider confidence and knowledge are necessary to achieve this end.

  11. A global test for gene‐gene interactions based on random matrix theory

    Science.gov (United States)

    Amos, Christopher I.; Moore, Jason H.

    2016-01-01

    ABSTRACT Statistical interactions between markers of genetic variation, or gene‐gene interactions, are believed to play an important role in the etiology of many multifactorial diseases and other complex phenotypes. Unfortunately, detecting gene‐gene interactions is extremely challenging due to the large number of potential interactions and ambiguity regarding marker coding and interaction scale. For many data sets, there is insufficient statistical power to evaluate all candidate gene‐gene interactions. In these cases, a global test for gene‐gene interactions may be the best option. Global tests have much greater power relative to multiple individual interaction tests and can be used on subsets of the markers as an initial filter prior to testing for specific interactions. In this paper, we describe a novel global test for gene‐gene interactions, the global epistasis test (GET), that is based on results from random matrix theory. As we show via simulation studies based on previously proposed models for common diseases including rheumatoid arthritis, type 2 diabetes, and breast cancer, our proposed GET method has superior performance characteristics relative to existing global gene‐gene interaction tests. A glaucoma GWAS data set is used to demonstrate the practical utility of the GET method. PMID:27386793

  12. Strength and fatigue testing of large size wind turbines rotors. Vol. II: Full size natural vibration and static strength test, a reference case

    Energy Technology Data Exchange (ETDEWEB)

    Arias, F.; Soria, E.

    1996-12-01

    This report shows the methods and procedures selected to define a strength test for large size wind turbine, anyway in particular it application on a 500 kW blade and it results obtained in the test carried out in july of 1995 in Asinel`s test plant (Madrid). Henceforth, this project is designed in an abbreviate form whit the acronym SFAT. (Author)

  13. Embedded Platform for Automatic Testing and Optimizing of FPGA Based Cryptographic True Random Number Generators

    Directory of Open Access Journals (Sweden)

    M. Varchola

    2009-12-01

    Full Text Available This paper deals with an evaluation platform for cryptographic True Random Number Generators (TRNGs based on the hardware implementation of statistical tests for FPGAs. It was developed in order to provide an automatic tool that helps to speed up the TRNG design process and can provide new insights on the TRNG behavior as it will be shown on a particular example in the paper. It enables to test sufficient statistical properties of various TRNG designs under various working conditions on the fly. Moreover, the tests are suitable to be embedded into cryptographic hardware products in order to recognize TRNG output of weak quality and thus increase its robustness and reliability. Tests are fully compatible with the FIPS 140 standard and are implemented by the VHDL language as an IP-Core for vendor independent FPGAs. A recent Flash based Actel Fusion FPGA was chosen for preliminary experiments. The Actel version of the tests possesses an interface to the Actel’s CoreMP7 softcore processor that is fully compatible with the industry standard ARM7TDMI. Moreover, identical tests suite was implemented to the Xilinx Virtex 2 and 5 in order to compare the performance of the proposed solution with the performance of already published one based on the same FPGAs. It was achieved 25% and 65% greater clock frequency respectively while consuming almost equal resources of the Xilinx FPGAs. On the top of it, the proposed FIPS 140 architecture is capable of processing one random bit per one clock cycle which results in 311.5 Mbps throughput for Virtex 5 FPGA.

  14. The effect of financial incentives on chlamydia testing rates: Evidence from a randomized experiment☆

    Science.gov (United States)

    Dolan, Paul; Rudisill, Caroline

    2014-01-01

    Financial incentives have been used in a variety of settings to motivate behaviors that might not otherwise be undertaken. They have been highlighted as particularly useful in settings that require a single behavior, such as appointment attendance or vaccination. They also have differential effects based on socioeconomic status in some applications (e.g. smoking). To further investigate these claims, we tested the effect of providing different types of non-cash financial incentives on the return rates of chlamydia specimen samples amongst 16–24 year-olds in England. In 2011 and 2012, we ran a two-stage randomized experiment involving 2988 young people (1489 in Round 1 and 1499 in Round 2) who requested a chlamydia screening kit from Freetest.me, an online and text screening service run by Preventx Limited. Participants were randomized to control, or one of five types of financial incentives in Round 1 or one of four financial incentives in Round 2. We tested the effect of five types of incentives on specimen sample return; reward vouchers of differing values, charity donation, participation in a lottery, choices between a lottery and a voucher and including vouchers of differing values in the test kit prior to specimen return. Financial incentives of any type, did not make a significant difference in the likelihood of specimen return. The more deprived individuals were, as calculated using Index of Multiple Deprivation (IMD), the less likely they were to return a sample. The extent to which incentive structures influenced sample return was not moderated by IMD score. Non-cash financial incentives for chlamydia testing do not seem to affect the specimen return rate in a chlamydia screening program where test kits are requested online, mailed to requestors and returned by mail. They also do not appear more or less effective in influencing test return depending on deprivation level. PMID:24373390

  15. A randomized trial of urodynamic testing before stress-incontinence surgery.

    Science.gov (United States)

    Nager, Charles W; Brubaker, Linda; Litman, Heather J; Zyczynski, Halina M; Varner, R Edward; Amundsen, Cindy; Sirls, Larry T; Norton, Peggy A; Arisco, Amy M; Chai, Toby C; Zimmern, Philippe; Barber, Matthew D; Dandreo, Kimberly J; Menefee, Shawn A; Kenton, Kimberly; Lowder, Jerry; Richter, Holly E; Khandwala, Salil; Nygaard, Ingrid; Kraus, Stephen R; Johnson, Harry W; Lemack, Gary E; Mihova, Marina; Albo, Michael E; Mueller, Elizabeth; Sutkin, Gary; Wilson, Tracey S; Hsu, Yvonne; Rozanski, Thomas A; Rickey, Leslie M; Rahn, David; Tennstedt, Sharon; Kusek, John W; Gormley, E Ann

    2012-05-24

    Urodynamic studies are commonly performed in women before surgery for stress urinary incontinence, but there is no good evidence that they improve outcomes. We performed a multicenter, randomized, noninferiority trial involving women with uncomplicated, demonstrable stress urinary incontinence to compare outcomes after preoperative office evaluation and urodynamic tests or evaluation only. The primary outcome was treatment success at 12 months, defined as a reduction in the score on the Urogenital Distress Inventory of 70% or more and a response of "much better" or "very much better" on the Patient Global Impression of Improvement. The predetermined noninferiority margin was 11 percentage points. A total of 630 women were randomly assigned to undergo office evaluation with urodynamic tests or evaluation only (315 per group); the proportion in whom treatment was successful was 76.9% in the urodynamic-testing group versus 77.2% in the evaluation-only group (difference, -0.3 percentage points; 95% confidence interval, -7.5 to 6.9), which was consistent with noninferiority. There were no significant between-group differences in secondary measures of incontinence severity, quality of life, patient satisfaction, rates of positive provocative stress tests, voiding dysfunction, or adverse events. Women who underwent urodynamic tests were significantly less likely to receive a diagnosis of overactive bladder and more likely to receive a diagnosis of voiding-phase dysfunction, but these changes did not lead to significant between-group differences in treatment selection or outcomes. For women with uncomplicated, demonstrable stress urinary incontinence, preoperative office evaluation alone was not inferior to evaluation with urodynamic testing for outcomes at 1 year. (Funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ClinicalTrials.gov number, NCT00803959.).

  16. The effect of financial incentives on chlamydia testing rates: evidence from a randomized experiment.

    Science.gov (United States)

    Dolan, Paul; Rudisill, Caroline

    2014-03-01

    Financial incentives have been used in a variety of settings to motivate behaviors that might not otherwise be undertaken. They have been highlighted as particularly useful in settings that require a single behavior, such as appointment attendance or vaccination. They also have differential effects based on socioeconomic status in some applications (e.g. smoking). To further investigate these claims, we tested the effect of providing different types of non-cash financial incentives on the return rates of chlamydia specimen samples amongst 16-24 year-olds in England. In 2011 and 2012, we ran a two-stage randomized experiment involving 2988 young people (1489 in Round 1 and 1499 in Round 2) who requested a chlamydia screening kit from Freetest.me, an online and text screening service run by Preventx Limited. Participants were randomized to control, or one of five types of financial incentives in Round 1 or one of four financial incentives in Round 2. We tested the effect of five types of incentives on specimen sample return; reward vouchers of differing values, charity donation, participation in a lottery, choices between a lottery and a voucher and including vouchers of differing values in the test kit prior to specimen return. Financial incentives of any type, did not make a significant difference in the likelihood of specimen return. The more deprived individuals were, as calculated using Index of Multiple Deprivation (IMD), the less likely they were to return a sample. The extent to which incentive structures influenced sample return was not moderated by IMD score. Non-cash financial incentives for chlamydia testing do not seem to affect the specimen return rate in a chlamydia screening program where test kits are requested online, mailed to requestors and returned by mail. They also do not appear more or less effective in influencing test return depending on deprivation level. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. The Shock and Vibration Bulletin. Part 2. Dynamic Testing, Flight Vehicle Dynamics, Seismic Loads and Fluid-Structure Interaction

    Science.gov (United States)

    1985-06-01

    ARTHQUAKE IJIDUCED MjOTION FNVIRONMENTS Ml FRAMED BUILDINGS; ... .....101 A. Longino and J. Molammadi, Minois Institute of l 1 Technology. Chicago...reproduce triaxial of the test. motion was evaluated at White Sands Missile Range (WSMR), New Mexico , in In response to these objectives the early 1960...STRUCTURAL MODELING J. W. Jeter and P. H. Merritt Albuquerque Engineering Center Hughes Aircraft Company Albuquerque, New Mexico 87119 Finite element

  18. A Permutation-Randomization Approach to Test the Spatial Distribution of Plant Diseases.

    Science.gov (United States)

    Lione, G; Gonthier, P

    2016-01-01

    The analysis of the spatial distribution of plant diseases requires the availability of trustworthy geostatistical methods. The mean distance tests (MDT) are here proposed as a series of permutation and randomization tests to assess the spatial distribution of plant diseases when the variable of phytopathological interest is categorical. A user-friendly software to perform the tests is provided. Estimates of power and type I error, obtained with Monte Carlo simulations, showed the reliability of the MDT (power > 0.80; type I error pathogens causing root rot on conifers was successfully performed by verifying the consistency between the MDT responses and previously published data. An application of the MDT was carried out to analyze the relation between the plantation density and the distribution of the infection of Gnomoniopsis castanea, an emerging fungal pathogen causing nut rot on sweet chestnut. Trees carrying nuts infected by the pathogen were randomly distributed in areas with different plantation densities, suggesting that the distribution of G. castanea was not related to the plantation density. The MDT could be used to analyze the spatial distribution of plant diseases both in agricultural and natural ecosystems.

  19. Selection of locations of knots for linear splines in random regression test-day models.

    Science.gov (United States)

    Jamrozik, J; Bohmanova, J; Schaeffer, L R

    2010-04-01

    Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits.

  20. Test-Enhanced E-Learning Strategies in Postgraduate Medical Education: A Randomized Cohort Study.

    Science.gov (United States)

    DelSignore, Lisa A; Wolbrink, Traci A; Zurakowski, David; Burns, Jeffrey P

    2016-11-21

    The optimal design of pedagogical strategies for e-learning in graduate and postgraduate medical education remains to be determined. Video-based e-learning use is increasing, with initial research suggesting that taking short breaks while watching videos (independent of answering test questions) may improve learning by focusing attention on the content presented. Interspersed test questions may also improve knowledge acquisition and retention. To examine the effect of interspersed test questions and periodic breaks on immediate knowledge acquisition and retention at 6 months by pediatric residents engaged in video-based e-learning. First- and second-year pediatric residents were randomized to 1 of the following 3 groups: viewing the complete video uninterrupted (full video), viewing the video interrupted with unrelated logic puzzles (logic puzzles), or viewing the video interrupted with brief comprehension test questions (short answer questions). Residents answered pre- and post-tests before and after video viewing, followed by a retention test at 6 months. Primary outcome included comparison of the change in test scores between groups. A total of 49 residents completed the initial testing session. All 3 learning groups had comparable mean increases in immediate knowledge gain, but with no significant differences between groups (F2,46=0.35, P=.71). Thirty-five residents completed retention testing with comparable degrees of knowledge retention in the full video and short answer test questions groups (P<.001), but no significant change in the logic puzzles group (F1,32=2.44, P=.13). Improved knowledge gain was not demonstrated among residents answering interspersed questions or completing logic puzzles during interrupted online video viewing when compared with residents viewing uninterrupted video content. However, residents who either participated in uninterrupted video viewing or answered interspersed questions during interrupted video viewing demonstrated

  1. TESTING BRAND VALUE MEASUREMENT METHODS IN A RANDOM COEFFICIENT MODELING FRAMEWORK

    Directory of Open Access Journals (Sweden)

    Szõcs Attila

    2014-07-01

    Full Text Available Our objective is to provide a framework for measuring brand equity, that is, the added value to the product endowed by the brand. Based on a demand and supply model, we propose a structural model that enables testing the structural effect of brand equity (demand side effect on brand value (supply side effect, using Monte Carlo simulation. Our main research question is which of the three brand value measurement methods (price premium, revenue premium and profit premium is more suitable from the perspective of the structural link between brand equity and brand value. Our model is based on recent developments in random coefficients model applications.

  2. Hand vibration: non-contact measurement of local transmissibility.

    Science.gov (United States)

    Scalise, Lorenzo; Rossetti, Francesco; Paone, Nicola

    2007-10-01

    Grip and push forces required for the use of vibrating tools are considered important influencing inputs for the assessment of hand-vibration transmissibility (TR). At present TR measurements are usually referred to the palm of the hand The aims of the present paper are: to present an original measurement procedure for non-contact assessment of the transmissibility of fingers; to report TR data measured on six points of the hand of nine subjects; to correlate TR with: grip, push, hand volume and BMI. Tests have been carried out using a cylindrical handle mounted on an shaker. A laser Doppler vibrometer is used to measure the vibration velocity. Push force is measured using a force platform, whereas grip force is measured using a capacitive pressure sensor matrix wrapped around the handle. Tests have been conducted on nine healthy subjects. Proximal and distal regions of the second, fourth and fifth fingers have been investigated. Tests were carried out using a push force of: 25, 50 and 75 N. The excitation signal was a broadband random vibration in the band 16-400 Hz with un-weighted rms acceleration level of 6 m/s(2). Results show how in general TR values measured on distal points are higher respect to the proximal points. A resonance peak is present for all the measured points in the band 55-80 Hz. ANOVA analysis showed that TR is not significantly dependent on: BMI, hand volume and push force alone. While TR is significantly dependent on: grip force alone, measurement positions and grip and push force together. The proposed procedure shows the advantage to allow local vibration measurement directly on the fingers without the necessity to apply any contact sensor. Results demonstrate how the transmissibility is significantly different on the point where the acceleration is measured.

  3. Testing the ability of a proposed geotechnical based method to evaluate the liquefaction potential analysis subjected to earthquake vibrations

    Science.gov (United States)

    Abbaszadeh Shahri, A.; Behzadafshar, K.; Esfandiyari, B.; Rajablou, R.

    2010-12-01

    During the earthquakes a number of earth dams have had severe damages or suffered major displacements as a result of liquefaction, thus modeling by computer codes can provide a reliable tool to predict the response of the dam foundation against earthquakes. These modeling can be used in the design of new dams or safety assessments of existing ones. In this paper, on base of the field and laboratory tests and by combination of several software packages a seismic geotechnical based analysis procedure is proposed and verified by comparison with computer model tests, field and laboratory experiences. Verification or validation of the analyses relies to ability of the applied computer codes. By use of Silakhor earthquake (2006, Ms 6.1) and in order to check the efficiency of the proposed framework, the procedure is applied to the Korzan earth dam of Iran which is located in Hamedan Province to analyze and estimate the liquefaction and safety factor. Design and development of a computer code by authors which named as “Abbas Converter” with graphical user interface which operates as logic connecter function that can computes and models the soil profiles is the critical point of this study and the results are confirm and proved the ability of the generated computer code on evaluation of soil behavior under the earthquake excitations. Also this code can make and render facilitate this study more than previous have done, and take over the encountered problem.

  4. Probing crystal structure and mesoscale assembly of cellulose microfibrils in plant cell walls, tunicate tests, and bacterial films using vibrational sum frequency generation (SFG) spectroscopy.

    Science.gov (United States)

    Lee, Christopher M; Kafle, Kabindra; Park, Yong Bum; Kim, Seong H

    2014-06-14

    This study reports that the noncentrosymmetry and phase synchronization requirements of the sum frequency generation (SFG) process can be used to distinguish the three-dimensional organization of crystalline cellulose distributed in amorphous matrices. Crystalline cellulose is produced as microfibrils with a few nanometer diameters by plants, tunicates, and bacteria. Crystalline cellulose microfibrils are embedded in wall matrix polymers and assembled into hierarchical structures that are precisely designed for specific biological and mechanical functions. The cellulose microfibril assemblies inside cell walls are extremely difficult to probe. The comparison of vibrational SFG spectra of uniaxially-aligned and disordered films of cellulose Iβ nanocrystals revealed that the spectral features cannot be fully explained with the crystallographic unit structure of cellulose. The overall SFG intensity, the alkyl peak shape, and the alkyl/hydroxyl intensity ratio are sensitive to the lateral packing and net directionality of the cellulose microfibrils within the SFG coherence length scale. It was also found that the OH SFG stretch peaks could be deconvoluted to find the polymorphic crystal structures of cellulose (Iα and Iβ). These findings were used to investigate the cellulose crystal structure and mesoscale cellulose microfibril packing in intact plant cell walls, tunicate tests, and bacterial films.

  5. Comparing cost effects of two quality strategies to improve test ordering in primary care: a randomized trial.

    NARCIS (Netherlands)

    Verstappen, W.H.; Merode, F. van; Grimshaw, J.; Dubois, W.; Grol, R.P.T.M.; Weijden, T. van der

    2004-01-01

    OBJECTIVE: To determine the costs and cost reductions of an innovative strategy aimed at improving test ordering routines of primary care physicians, compared with a traditional strategy. DESIGN: Multicenter randomized controlled trial with randomization at the local primary care physicians group

  6. A Cluster Randomized Controlled Trial Testing the Effectiveness of Houvast: A Strengths-Based Intervention for Homeless Young Adults

    Science.gov (United States)

    Krabbenborg, Manon A. M.; Boersma, Sandra N.; van der Veld, William M.; van Hulst, Bente; Vollebergh, Wilma A. M.; Wolf, Judith R. L. M.

    2017-01-01

    Objective: To test the effectiveness of Houvast: a strengths-based intervention for homeless young adults. Method: A cluster randomized controlled trial was conducted with 10 Dutch shelter facilities randomly allocated to an intervention and a control group. Homeless young adults were interviewed when entering the facility and when care ended.…

  7. Testing in a Random Effects Panel Data Model with Spatially Correlated Error Components and Spatially Lagged Dependent Variables

    Directory of Open Access Journals (Sweden)

    Ming He

    2015-11-01

    Full Text Available We propose a random effects panel data model with both spatially correlated error components and spatially lagged dependent variables. We focus on diagnostic testing procedures and derive Lagrange multiplier (LM test statistics for a variety of hypotheses within this model. We first construct the joint LM test for both the individual random effects and the two spatial effects (spatial error correlation and spatial lag dependence. We then provide LM tests for the individual random effects and for the two spatial effects separately. In addition, in order to guard against local model misspecification, we derive locally adjusted (robust LM tests based on the Bera and Yoon principle (Bera and Yoon, 1993. We conduct a small Monte Carlo simulation to show the good finite sample performances of these LM test statistics and revisit the cigarette demand example in Baltagi and Levin (1992 to illustrate our testing procedures.

  8. Stroboscopic shearography for vibration analysis

    Science.gov (United States)

    Steinchen, Wolfgang; Kupfer, Gerhard; Maeckel, Peter; Voessing, Frank

    1999-09-01

    Digital Shearography, a laser interferometric technique in conjunction with the digital image processing, has the potential for vibration analysis due to its simple optical system and insensitivity against small rigid body motions. This paper will focus on its recent developments for vibration analysis and for nondestructive testing (NDT) by dynamic (harmonical) excitation. With the introduction of real time observation using automatically refreshing reference frame, both small and large rigid body motions are greatly suppressed. The development of a smaller and more mobile measuring device in conjunction with a user guided comfortable program Shearwin enables the digital shearography to be applied easily as an industrial online testing tool.

  9. A randomized trial to test the effectiveness of art therapy for children with asthma.

    Science.gov (United States)

    Beebe, Anya; Gelfand, Erwin W; Bender, Bruce

    2010-08-01

    Art therapy has been used to help children cope with chronic illness but has not been specifically tested with children who have asthma. To test an art therapy intervention in a randomized controlled trial in children with asthma. Twenty-two children with asthma were randomized to an active art therapy or wait-list control group. Those in the active art therapy group participated in 60-minute art therapy sessions once a week for 7 weeks. Sessions included specific art therapy tasks designed to encourage expression, discussion, and problem-solving in response to the emotional burden of chronic illness. Measures taken at baseline, immediately after, and 6 months after the final art therapy session included the Formal Elements Art Therapy Scale applied to the Person Picking an Apple from a Tree assessment, the parent and child versions of the Pediatric Quality of Life Asthma Module, and the Beck Youth Inventories. Those children assigned to the wait-list control group completed all evaluations at the same intervals as the children receiving art therapy but did not receive the art therapy interventions. Score changes from baseline to completion of art therapy indicated (1) improved problem-solving and affect drawing scores; (2) improved worry, communication, and total quality of life scores; and (3) improved Beck anxiety and self concept scores in the active group relative to the control group. At 6 months, the active group maintained some positive changes relative to the control group including (1) drawing affect scores, (2) the worry and quality of life scores, and (3) the Beck anxiety score. Frequency of asthma exacerbations before and after the 6-month study interval did not differ between the 2 groups. This was the first randomized trial demonstrating that children with asthma receive benefit from art therapy that includes decreased anxiety and increased quality of life. Copyright 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All

  10. Local vibration enhanced the efficacy of passive exercise on mitigating bone loss in hindlimb unloading rats

    Science.gov (United States)

    Huang, Yunfei; Luan, Huiqin; Sun, Lianwen; Bi, Jingfang; Wang, Ying; Fan, Yubo

    2017-08-01

    Spaceflight induced bone loss is seriously affecting astronauts. Mechanical stimulation from exercise has been shown to restrain bone resorption as well as improve bone formation. Current exercise countermeasures in space cannot prevent it completely. Active exercise may convert to passive exercise in some ways because of the loss of gravity stimulus and inertia of exercise equipment. The aim of this study was to compare the efficacy of passive exercise or/and local vibration on counteracting the deterioration of the musculoskeletal system, including bone, muscle and tendons in tail-suspended rats. We hypothesized that local vibration could enhance the efficacy of passive exercise on countering bone loss. 40 Sprague Dawley rats were randomly distributed into five groups (n = 8, each): tail-suspension (TS), TS+35 Hz vibration (TSV), TS + passive exercise (TSP), TS + passive exercise coupled with 35 Hz vibration (TSPV) and control (CON). Passive exercise or/and local vibration was performed for 21 days. On day 0 and 21, bone mineral density (BMD) was observed by dual energy X-ray absorptiometry (DXA), and trabecular microstructure was evaluated by microcomputer tomography (μCT) analysis in vivo. Mechanical properties of tibia and tendon were determined by a mechanical testing system. Soleus and bone ash weight was tested by an electronic balance. Results showed that the passive exercise could not prevent the decrease of trabecular BMD, microstructure and bone ash weight induced by TS, whereas vibration and passive exercise coupled with local vibration (PV) could. Biomechanical properties of the tibia and tendon in TSPV group significantly increased compared with TS group. In summary, PV in this study was the best method in preventing weightlessness-induced bone loss. Consistent with our hypothesis, local vibration partly enhanced the effect of passive exercise. Furthermore, this study will be useful in improving countermeasure for astronauts, but also for the

  11. Comparative analysis of computerized random-dot stereogram in stereopsis and TNO test on postcataract patients

    Directory of Open Access Journals (Sweden)

    Qiang Wang

    2015-06-01

    Full Text Available AIM:To compare the inspection result of computerized random-dot stereotest(CRDSwith TNO test and to study the clinical value of CRDS.METHODS: Seventy-eight patients who received bilateral phacoemulsification from Januray, 2011 to June, 2011 were involved. The operations were performed by the same surgeon. Three months after the operation, CRDS and TNO test were used to evaluate the patients' stereopsis respectively. The inspection results of the two methods were compared.RESULTS:All patients presented stereoscopic vision. There were 26 patients with foveal stereoacuity, 14 with macular stereoscopic vision and 38 with peripheral stereovision measured with CRDS, while it was 24, 11, 43 measured with TNO test. There were 32 patients with normal stereopsis, 46 patients with abnormal stereopsis and 35 patients with normal stereopsis, 43 patients with abnormal stereopsis respectively measured with CRDS and TNO test. No significant differences were found between the two methods.CONCLUSION: The inspection result of CRDS has a high coherence with that of TNO test. It suggests that the CRDS is a reliable method for stereoaeuity evaluation in post-operative patients.

  12. Skin sensitivity to rocuronium and vecuronium: a randomized controlled prick-testing study in healthy volunteers.

    Science.gov (United States)

    Dhonneur, Gilles; Combes, Xavier; Chassard, Didier; Merle, Jean Claude

    2004-04-01

    Prick tests are frequently used for the authentication of neuromuscular blocking drugs (NMBDs) as causative drugs for anaphylactic reactions during anesthesia. Unfortunately, the actual threshold concentration for skin testing remains debatable for most NMBDs. We studied the flare and wheal responses to prick tests with rocuronium and vecuronium. Thirty healthy, nonatopic, anesthesia-naive male and female volunteers (14 men and 16 women) from 18 to 40 yr of age were assigned randomly to receive a total of 10 prick tests-4 ascending dilutions (1:1000, 1:100, 1:10, and 1) of rocuronium and vecuronium and 2 controls-on both forearms. An assessor blinded to the assignment monitored systemic and skin responses to NMBDs and measured wheal and flare surfaces immediately after and 15 min after prick tests. None of the volunteers experienced any immediate systemic or cutaneous responses to rocuronium or vecuronium. Although a dilution of 1:1000 of both NMBDs failed to promote any skin response at 15 min, 50% and 40% of the subjects had a positive skin reaction to undiluted rocuronium and vecuronium, respectively. We demonstrated a sex effect related to smaller threshold concentration-induced cutaneous reactions in female volunteers to both muscle relaxants. Our observation questions the reliability of prick testing with undiluted solutions of rocuronium and vecuronium for the diagnosis of allergy. Building concentration-skin response curves to prick tests with rocuronium and vecuronium in healthy, nonatopic, anesthesia-naive male and female volunteers demonstrated that the nonreactive concentration for both muscle relaxants is the 1:1000 dilution of the stock solutions. Our observation calls into question the past practice of prick-testing skin for sensitivity to neuromuscular blocking drugs by using undiluted solutions.

  13. THE POTENTIAL NEURAL MECHANISMS OF ACUTE INDIRECT VIBRATION

    Directory of Open Access Journals (Sweden)

    Darryl J. Cochrane

    2011-03-01

    Full Text Available There is strong evidence to suggest that acute indirect vibration acts on muscle to enhance force, power, flexibility, balance and proprioception suggesting neural enhancement. Nevertheless, the neural mechanism(s of vibration and its potentiating effect have received little attention. One proposal suggests that spinal reflexes enhance muscle contraction through a reflex activity known as tonic vibration stretch reflex (TVR, which increases muscle activation. However, TVR is based on direct, brief, and high frequency vibration (>100 Hz which differs to indirect vibration, which is applied to the whole body or body parts at lower vibration frequency (5-45 Hz. Likewise, muscle tuning and neuromuscular aspects are other candidate mechanisms used to explain the vibration phenomenon. But there is much debate in terms of identifying which neural mechanism(s are responsible for acute vibration; due to a number of studies using various vibration testing protocols. These protocols include: different methods of application, vibration variables, training duration, exercise types and a range of population groups. Therefore, the neural mechanism of acute vibration remain equivocal, but spinal reflexes, muscle tuning and neuromuscular aspects are all viable factors that may contribute in different ways to increasing muscular performance. Additional research is encouraged to determine which neural mechanism(s and their contributions are responsible for acute vibration. Testing variables and vibration applications need to be standardised before reaching a consensus on which neural mechanism(s occur during and post-vibration

  14. Temperature and chain length dependence of ultrafast vibrational dynamics of thiocyanate in alkylimidazolium ionic liquids: A random walk on a rugged energy landscape

    Science.gov (United States)

    Brinzer, Thomas; Garrett-Roe, Sean

    2017-11-01

    Ultrafast two-dimensional infrared spectroscopy of a thiocyanate vibrational probe (SCN-) was used to investigate local dynamics in alkylimidazolium bis-[trifluoromethylsulfonyl]imide ionic liquids ([Imn,1][Tf2N], n = 2, 4, 6) at temperatures from 5 to 80 °C. The rate of frequency fluctuations reported by SCN- increases with increasing temperature and decreasing alkyl chain length. Temperature-dependent correlation times scale proportionally to temperature-dependent bulk viscosities of each ionic liquid studied. A multimode Brownian oscillator model demonstrates that very low frequency (modes primarily drive the observed spectral diffusion and that these modes broaden and blue shift on average with increasing temperature. An Arrhenius analysis shows activation barriers for local motions around the probe between 5.5 and 6.5 kcal/mol that are very similar to those for translational diffusion of ions. [Im6,1][Tf2N] shows an unexpected decrease in activation energy compared to [Im4,1][Tf2N] that may be related to mesoscopically ordered polar and nonpolar domains. A model of dynamics on a rugged potential energy landscape provides a unifying description of the observed Arrhenius behavior and the Brownian oscillator model of the low frequency modes.

  15. Investigation and analysis the vibration of handles of chainsaw without cutting

    Directory of Open Access Journals (Sweden)

    M Feyzi

    2016-04-01

    (VMI-192. The accelerometer mounted on an adapter inserted between the handle and accelerometer. The experiments were conducted in split plot completely randomized design. Ninety tests in two handles, three speeds of engine, three perpendicular axes and five repeats were conducted. The vibration acceleration at various conditions was measured and the root mean square of vibration acceleration was calculated based on acceleration-time spectrum. To investigate the characteristics of vibration in different speeds, the vibration spectrums in time domain were converted to spectrums in frequency domain. The frequency weighted RMS acceleration at 1/3rd octave bands from 6.3Hz to 1250Hz and the vibration total value was calculated from frequency spectrum. To analyze the obtained data, SAS software was used. Furthermore, the Duncan's multiple range tests were used to compare the RMS values. Results and Discussion: Main source of vibration of chainsaw was single cylinder engine. The acceleration spectra of employed chainsaw had peaks in frequencies in accordance with the speed of engine. These peaks in 2800 rpm, 10000 rpm and 13300 rpm speeds of engine occurred in 46.5Hz, 166.5Hz and 221.5Hz, respectively. To achieve a safe design for handle of portable tools, identifying the frequency which leads to the maximum value of vibration acceleration is very useful. To avoid the resonance phenomenon, the natural frequency of handle must be far from dominant frequency of engine. The results of ANOVA showed that the RMS acceleration in different axes and different speeds were significant at 1% level. The maximum value of vibration acceleration, at idling engine speed, occurred in the lateral axis. In addition, the mentioned variable was maximized in normal and axial axes at nominal and racing speeds, respectively. The total value of vibration was increased when the speed of engine moving away from nominal speed. This increase in rear handle is very larger than front handle. The total

  16. 77 FR 72905 - Pipeline Safety: Random Drug Testing Rate; Contractor MIS Reporting; and Obtaining DAMIS Sign-In...

    Science.gov (United States)

    2012-12-06

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF TRANSPORTATION Pipeline and Hazardous Materials Safety Administration Pipeline Safety: Random Drug Testing Rate; Contractor MIS Reporting; and Obtaining DAMIS Sign-In Information AGENCY: Pipeline and Hazardous Materials...

  17. Effects of a web-based decision aid regarding diagnostic self-testing. A single-blind randomized controlled trial

    NARCIS (Netherlands)

    Ickenroth, M.H.; Grispen, J.E.; Vries, N.K. de; Dinant, G.J.; Ronda, G.; Weijden, T.T. van der

    2016-01-01

    Currently, there are many diagnostic self-tests on body materials available to consumers. The aim of this study was to assess the effect of an online decision aid on diagnostic self-testing for cholesterol and diabetes on knowledge among consumers with an intention to take these tests. A randomized

  18. Brain palpation from physiological vibrations using MRI

    OpenAIRE

    Zorgani, Ali; Souchon, Rémi; Dinh, Au-Hoang; Chapelon, Jean-Yves; Ménager, Jean-Michel; Lounis, Samir; Rouvière, Olivier; Catheline, Stefan

    2015-01-01

    It is commonly supposed that noise obscures but does not contain useful information. However, in wave physics and especially, seismology, scientists developed some tools known as “noise correlation” to extract useful information and construct images from the random vibrations of a medium. Living tissues are full of unexploited vibrations as well. In this manuscript, we show that noise correlation techniques in the brain using MRI can conduct to a tomography related to the stiffness that physi...

  19. Mobile phone generated vibrations used to detect diabetic peripheral neuropathy.

    Science.gov (United States)

    May, Jonathan David; Morris, Matthew William John

    2017-12-01

    In the current United Kingdom population the incidence of diabetic peripheral neuropathy is increasing. The presence of diabetic neuropathy affects decision making and treatment options. This study seeks to evaluate if the vibrations generated from a mobile phone can be used to screen patients for diabetic peripheral neuropathy. This study comprised of 61 patients; a control group of 21 patients; a lower limb injury group of 19 patients; a diabetic peripheral neuropathy group of 21 patients. The control and injury group were recruited randomly from fracture clinics. The diabetic peripheral neuropathy group were randomly recruited from the diabetic foot clinic. The 61 patients were examined using a 10g Semmes-Weinstein monofilament, a 128Hz tuning fork and a vibrating mobile phone. The points tested were, index finger, patella, lateral malleoli, medial malleoli, heel, first and fifth metatarsal heads. The most accurate location of all the clinical tests was the head of the 1st metatarsal at 0.86. The overall accuracy of the tuning fork was 0.77, the ten gram monofilament 0.79 and the mobile phone accuracy was 0.88. The control group felt 420 of 441 tests (95%). The injury group felt 349 of 399 tests (87%). The neuropathic group felt 216 of 441 tests (48%). There is a significant difference in the number of tests felt between the control and both the injury and neuropathic groups. pdiabetic peripheral neuropathy. The most accurate location to test for diabetic peripheral neuropathy is the head of the 1st metatarsal. Screening for diabetic peripheral neuropathy in the index finger and patella were inaccurate. An injury to the lower limb affects the patient's vibration sensation, we would therefore recommend screening the contralateral limb to the injury. This study represents level II evidence of a new diagnostic investigation. Copyright © 2016 European Foot and Ankle Society. All rights reserved.

  20. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations. Phase 5B: Analysis of gust alleviation methods and rotor dynamic stability

    Science.gov (United States)

    Hohenemser, K. H.; Yin, S. K.

    1971-01-01

    The effects of various gust alleviation methods on the random blade response in flapping were studied analytically, assuming a rigid rotor support. The analytical model assumes rigid flapping blades with elastic root restraints. Linearized equations which are approximately valid at low lift conditions were used. Because of the interblade coupling from the feedback devices, the method of multiblade generalized coordinates was most convenient and was extended to include coning, differential coning, and warping of the rotor. The numerical examples cover the dynamic stability characteristics as affected by feedback gains of three- to six-bladed rotors. The number of blades had large effects on stability limits and modal time functions at these limits. The random flapping response of the blades to atmospheric turbulence was determined at 1.6 rotor advance ratio using feedback gains below the stability limit. The most effective reduction of the flapping response per unit gain was achieved with a rotor coning angle feedback.

  1. Cluster randomized trials in comparative effectiveness research: randomizing hospitals to test methods for prevention of healthcare-associated infections.

    Science.gov (United States)

    Platt, Richard; Takvorian, Samuel U; Septimus, Edward; Hickok, Jason; Moody, Julia; Perlin, Jonathan; Jernigan, John A; Kleinman, Ken; Huang, Susan S

    2010-06-01

    The need for evidence about the effectiveness of therapeutics and other medical practices has triggered new interest in methods for comparative effectiveness research. Describe an approach to comparative effectiveness research involving cluster randomized trials in networks of hospitals, health plans, or medical practices with centralized administrative and informatics capabilities. We discuss the example of an ongoing cluster randomized trial to prevent methicillin-resistant Staphylococcus aureus (MRSA) infection in intensive care units (ICUs). The trial randomizes 45 hospitals to: (a) screening cultures of ICU admissions, followed by Contact Precautions if MRSA-positive, (b) screening cultures of ICU admissions followed by decolonization if MRSA-positive, or (c) universal decolonization of ICU admissions without screening. All admissions to adult ICUs. The primary outcome is MRSA-positive clinical cultures occurring >or=2 days following ICU admission. Secondary outcomes include blood and urine infection caused by MRSA (and, separately, all pathogens), as well as the development of resistance to decolonizing agents. Recruitment of hospitals is complete. Data collection will end in Summer 2011. This trial takes advantage of existing personnel, procedures, infrastructure, and information systems in a large integrated hospital network to conduct a low-cost evaluation of prevention strategies under usual practice conditions. This approach is applicable to many comparative effectiveness topics in both inpatient and ambulatory settings.

  2. Perceptions of genetic testing for personalized nutrition: a randomized trial of DNA-based dietary advice.

    Science.gov (United States)

    Nielsen, Daiva E; Shih, Sarah; El-Sohemy, Ahmed

    2014-01-01

    Direct-to-consumer (DTC) genetic tests have facilitated easy access to personal genetic information related to health and nutrition; however, consumer perceptions of the nutritional information provided by these tests have not been evaluated. The objectives of this study were to assess individual perceptions of personalized nutrition and genetic testing and to determine whether a personalized nutrition intervention modifies perceptions. A double-blind, parallel-group, randomized controlled trial was conducted among healthy men and women aged 20-35 years (n = 138). Participants in the intervention group (n = 92) were given a report of DNA-based dietary advice and those in the control group (n = 46) were given a general dietary advice report. A survey was completed at baseline and 3 and 12 months after distributing the reports to assess perceptions between the two groups. No significant differences in perceptions of personalized nutrition and genetic testing were observed between the intervention and control group, so responses of both groups were combined. As compared to baseline, participant responses increased significantly toward the positive end of a Likert scale at 3 months for the statement 'I am interested in the relationship between diet and genetics' (mean change ± SD: 0.28 ± 0.99, p = 0.0002). The majority of participants indicated that a university research lab (47%) or health care professional (41%) were the best sources for obtaining accurate personal genetic information, while a DTC genetic testing company received the fewest selections (12%). Most participants (56%) considered dietitians to be the best source of personalized nutrition followed by medical doctors (27%), naturopaths (8%) and nurses (6%). These results suggest that perceptions of personalized nutrition changed over the course of the intervention. Individuals view a research lab or health care professional as better providers of genetic information than a DTC genetic testing company

  3. Mode shape expansions for the dynamic testing of cable domes considering random pretension deviations

    Science.gov (United States)

    Wu, Xiaoshun; Deng, Hua; Zhu, Dexi

    2017-04-01

    Cable domes maintain their structural stability and deformation resistance substantially depending on the geometrical stiffness contributed by pretension. Dynamic testing can be employed to monitor the possible stiffness degeneration caused by pretension deviations in existing cable domes. The measured incomplete mode shapes should be expanded for effectively evaluating the actual structural stiffness. However, conventional methods lose effectiveness for expanding mode shapes of cable domes whose modes are sensitive to the pretension deviations. A novel method is developed in this paper to expand the incomplete mode shapes of existing cable domes with random pretension deviations. For a monitored target mode of the existing structure, its mode shape can be approximately expressed as a linear combination of a few mode shapes of the ideal structure. Once their combinational coefficients are determined based on the measured incomplete mode shape, the expansion of this target mode is achieved. Two key steps are included: the determination of these so-called contribution modes and the estimation of their combinational coefficients. For the prescribed limit values of equivalent member length errors adopted to simulate random pretension deviations, contribution modes can be determined by considering the mode shape variations and mode jumpings. A proposed contribution mode effective independence (CMEI) method is further put forward to obtain the best estimate of combinational coefficients and the optimal layout of sensors. The numerical example of a cable dome illustrates the invalidation of the conventional expansion methods when random pretension deviations are considered. In contrast, the method proposed in this paper is validated to be effective and reliable even in the cases of severe modal variations and high noise levels.

  4. Testing the Predictions of Random Matrix Theory in Low Loss Wave Chaotic Scattering Systems

    Science.gov (United States)

    Yeh, Jen-Hao; Antonsen, Thomas; Ott, Edward; Anlage, Steven

    2013-03-01

    Wave chaos is a field where researchers apply random matrix theory (RMT) to predict the statistics of wave properties in complicated wave scattering systems. The RMT predictions have successfully demonstrated universality of the distributions of these wave properties, which only depend on the loss parameter of the system and the physical symmetry. Examination of these predictions in very low loss systems is interesting because extreme limits for the distribution functions and other predictions are encountered. Therefore, we use a wave-chaotic superconducting cavity to establish a low loss environment and test RMT predictions, including the statistics of the scattering (S) matrix and the impedance (Z) matrix, the universality (or lack thereof) of the Z- and S-variance ratios, and the statistics of the proper delay times of the Wigner-Smith time-delay matrix. We have applied an in-situ microwave calibration method (Thru-Reflection-Line method) to calibrate the cryostat system, and we also applied the random coupling model to remove the system-specific features. Our experimental results of different properties agree with the RMT predictions. This work is funded by the ONR/Maryland AppEl Center Task A2 (contract No. N000140911190), the AFOSR under grant FA95500710049, and Center for Nanophysics and Advanced Materials.

  5. Comparison of different ultrasonic vibration modes for post removal.

    Science.gov (United States)

    Braga, Neilor Mateus Antunes; Silva, Juliana Monteiro da; Carvalho-Júnior, Jacy Ribeiro de; Ferreira, Raquel Conceição; Saquy, Paulo César; Brito-Júnior, Manoel

    2012-01-01

    This in vitro study compared different ultrasonic vibration modes for intraradicular cast post removal. The crowns of 24 maxillary canines were removed, the roots were embedded in acrylic resin blocks, and the canals were treated endodontically. The post holes were prepared and root canal impressions were taken with self-cured resin acrylic. After casting, the posts were cemented with zinc phosphate cement. The samples were randomly distributed into 3 groups (n=8): G1: no ultrasonic vibration (control); G2: tip of the ultrasonic device positioned perpendicularly to core surface and close to the incisal edge; and G3: tip of the ultrasonic device positioned perpendicularly to core surface at cervical region, close to the line of cementation. An Enac OE-5 ultrasound unit with an ST-09 tip was used. All samples were submitted to the tensile test using an universal testing machine at a crosshead speed of 1 mm/min. Data were subjected to one-way ANOVA and Tukey's post-hoc tests (α=0.05). Mean values of the load to dislodge the posts (MPa) were: G1 = 4.6 (± 1.4) A; G2 = 2.8 (± 0.9) B, and G3= 0.9 (± 0.3) C. Therefore, the ultrasonic vibration applied with the tip of device close to the core's cervical area showed higher ability to reduce the retention of cast post to root canal.

  6. On Generating Optimal Signal Probabilities for Random Tests: A Genetic Approach

    Directory of Open Access Journals (Sweden)

    M. Srinivas

    1996-01-01

    Full Text Available Genetic Algorithms are robust search and optimization techniques. A Genetic Algorithm based approach for determining the optimal input distributions for generating random test vectors is proposed in the paper. A cost function based on the COP testability measure for determining the efficacy of the input distributions is discussed. A brief overview of Genetic Algorithms (GAs and the specific details of our implementation are described. Experimental results based on ISCAS-85 benchmark circuits are presented. The performance of our GAbased approach is compared with previous results. While the GA generates more efficient input distributions than the previous methods which are based on gradient descent search, the overheads of the GA in computing the input distributions are larger.

  7. Estimating a DIF decomposition model using a random-weights linear logistic test model approach.

    Science.gov (United States)

    Paek, Insu; Fukuhara, Hirotaka

    2015-09-01

    A differential item functioning (DIF) decomposition model separates a testlet item DIF into two sources: item-specific differential functioning and testlet-specific differential functioning. This article provides an alternative model-building framework and estimation approach for a DIF decomposition model that was proposed by Beretvas and Walker (2012). Although their model is formulated under multilevel modeling with the restricted pseudolikelihood estimation method, our approach illustrates DIF decomposition modeling that is directly built upon the random-weights linear logistic test model framework with the marginal maximum likelihood estimation method. In addition to demonstrating our approach's performance, we provide detailed information on how to implement this new DIF decomposition model using an item response theory software program; using DIF decomposition may be challenging for practitioners, yet practical information on how to implement it has previously been unavailable in the measurement literature.

  8. Aging effect on Executive Control in the Random Number Generation Test

    Directory of Open Access Journals (Sweden)

    Amer Cavalheiro Hamdan

    2006-12-01

    Full Text Available The decline of abilities related to Executive Control –EC with aging has been related with the Pre-Frontal System neurobiological aging. This study compared the score obtained in the Random Number Generation Test (RNG by two groups: 30 college students (older than 18 and 36 elderly (older than 60. This last group was divided according to the criteria of schooling in up to 8 years of schooling and over 8 years of schooling. The results show that the younger participants scored 0,344 ± 0,04 in the RNG test; the elderly with up to 8 years of schooling punctuated 0,432 ± 0,10 and that those who studied for 9 years or more reached a mean of 0,393 ± 0,05. The statistical analysis of these data suggest that the elderly performance in the RNG test (0,420 ± 0,09 was significantly worse when compared to the performance of the younger participants (t (64 = -3,9927; p = 0,0001, which confirms that the manipulation and inhibitory control abilities of information are decreased in older people, probably due to the natural aging process of the Frontal Cortex. Keywords: neuropsychology; aging; executive functions.

  9. Testing concordance of instrumental variable effects in generalized linear models with application to Mendelian randomization

    Science.gov (United States)

    Dai, James Y.; Chan, Kwun Chuen Gary; Hsu, Li

    2014-01-01

    Instrumental variable regression is one way to overcome unmeasured confounding and estimate causal effect in observational studies. Built on structural mean models, there has been considerale work recently developed for consistent estimation of causal relative risk and causal odds ratio. Such models can sometimes suffer from identification issues for weak instruments. This hampered the applicability of Mendelian randomization analysis in genetic epidemiology. When there are multiple genetic variants available as instrumental variables, and causal effect is defined in a generalized linear model in the presence of unmeasured confounders, we propose to test concordance between instrumental variable effects on the intermediate exposure and instrumental variable effects on the disease outcome, as a means to test the causal effect. We show that a class of generalized least squares estimators provide valid and consistent tests of causality. For causal effect of a continuous exposure on a dichotomous outcome in logistic models, the proposed estimators are shown to be asymptotically conservative. When the disease outcome is rare, such estimators are consistent due to the log-linear approximation of the logistic function. Optimality of such estimators relative to the well-known two-stage least squares estimator and the double-logistic structural mean model is further discussed. PMID:24863158

  10. Increased statistical power with combined independent randomization tests used with multiple-baseline design.

    Science.gov (United States)

    Tyrrell, Pascal N; Corey, Paul N; Feldman, Brian M; Silverman, Earl D

    2013-06-01

    Physicians often assess the effectiveness of treatments on a small number of patients. Multiple-baseline designs (MBDs), based on the Wampold-Worsham (WW) method of randomization and applied to four subjects, have relatively low power. Our objective was to propose another approach with greater power that does not suffer from the time requirements of the WW method applied to a greater number of subjects. The power of a design that involves the combination of two four-subject MBDs was estimated using computer simulation and compared with the four- and eight-subject designs. The effect of a delayed linear response to treatment on the power of the test was also investigated. Power was found to be adequate (>80%) for a standardized mean difference (SMD) greater than 0.8. The effect size associated with 80% power from combined tests was smaller than that of the single four-subject MBD (SMD=1.3) and comparable with the eight-subject MBD (SMD=0.6). A delayed linear response to the treatment resulted in important reductions in power (20-35%). By combining two four-subject MBD tests, an investigator can detect better effect sizes (SMD=0.8) and be able to complete a comparatively timelier and feasible study. Copyright © 2013 Elsevier Inc. All rights reserved.

  11. Optimal vibration stimulation to the neck extensor muscles using hydraulic vibrators to shorten saccadic reaction time.

    Science.gov (United States)

    Fujiwara, Katsuo; Kunita, Kenji; Furune, Naoe; Maeda, Kaoru; Asai, Hitoshi; Tomita, Hidehito

    2006-09-01

    Optimal vibration stimulation to the neck extensor muscles using hydraulic vibrators to shorten the saccadic reaction time was examined. Subjects were 14 healthy young adults. Visual targets (LEDs) were located 10 degrees left and right of a central point. The targets were alternately lit for random durations of 2-4 seconds in a resting neck condition and various vibration conditions, and saccadic reaction times were measured. Vibration amplitude was 0.5 mm in every condition. The upper trapezius muscles were vibrated at 40, 60, 80, and 100 Hz in a sub-maximum stretch condition in which the muscles were stretched at 70% of maximum stretch. In addition, the muscles were vibrated at 60 Hz with the muscles maximally stretched, with 70% vertical pressure without stretching, and with vibration applied to the skin in the same area as the muscle vibration. At 60, 80, and 100 Hz at 70% maximum stretch, saccadic reaction time shortened significantly compared with the resting neck condition. However, no significant difference in the reaction time was observed among the frequencies. The saccadic reaction times in the maximum stretch condition, muscle pressure condition, and skin contact condition did not differ significantly from that in the resting neck condition. Vibration stimulation to the trapezius with 60-100 Hz frequencies at 0.5 mm amplitude in the sub-maximum stretch condition was effective for shortening saccadic reaction time. The main mechanism appears to be Ia information originating from the muscle spindle.

  12. Effect of vibration stabilization of the process of postcritical deformation

    Science.gov (United States)

    Wildemann, V. E.; Lomakin, E. V.; Tretyakov, M. P.

    2016-03-01

    Results of the experimental study of vibration stabilization of the process of postcritical deformation during the tensile testing of solid cylindrical specimens made of 20 and 40Cr structural steels under additional vibrations are presented. The vibrations are implemented using cyclic torsion of the specimens at a small amplitude and a frequency of 10-30 Hz.

  13. A Comparison of Random Normal Scores Test under the F and Chi-Square Distributions to the 2x2x2 ANOVA Test.

    Science.gov (United States)

    Sawilowsky, Shlomo

    1985-01-01

    The Random Normal Scores Test (RNST) has been suggested as a powerful alternative to the use of the parametric analysis of variance (ANOVA) test when the underlying population is non-normally distributed. The major support for this suggestion rests on asymptotic theory. An empirical analysis of the RNST performed under the F and Chi-square…

  14. Bending stiffness evaluation of Teca and Guajará lumber through tests of transverse and longitudinal vibration - doi: 10.4025/actascitechnol.v34i1.10728

    Directory of Open Access Journals (Sweden)

    Marcelo Rodrigo Carreira

    2011-11-01

    Full Text Available The grading of structural lumber besides contributing for increasing the structure's safety, due to the reduction of the material variability, also allows its rational use. Due to the good correlation between strength and bending stiffness, the latter has been used in estimating the mechanical strength of lumber pieces since the 60’s. For industrial application, there are equipment and techniques to evaluate the bending stiffness of lumber, through dynamic tests such as the longitudinal vibration technique, also known as stress wave, and the transverse vibration technique. This study investigated the application of these two techniques in the assessment of the modulus of elasticity in bending of Teca beams (Tectona grandis, from reforestation, and of the tropical species Guajará (Micropholis venulosa. The modulus of elasticity estimated by dynamic tests showed good correlation with the modulus measured in the static bending test. Meantime, we observed that the accuracy of the longitudinal vibration technique was significantly reduced in the evaluation of the bending stiffness of Teca pieces due to the knots existing in this species.

  15. Normalization of vibration signals generated under highly varying speed and load with application to signal separation

    Science.gov (United States)

    Urbanek, Jacek; Barszcz, Tomasz; Strączkiewicz, Marcin; Jablonski, Adam

    2017-01-01

    The paper presents a normalization dedicated to transform non-stationary vibration signals into signals characterized by purely stationary properties. For this purpose, a novel class of generalized periodic signals is defined followed by a proposition of a normalization technique, which takes advantage of available, instantaneous values of operational parameters. Within the paper, a well-known discrete-random separation (DRS) technique is recalled as an exemplary technique, which has been restricted to stationary signals so far. The authors present a step-by-step adoption of the DRS to non-stationary signals. The method is applied to simulated signal, test rig signal, and a vibration signal from industrial object. Additionally, for the purpose of synthesis of simulated signal, a new model of multi-component vibrations generated under varying regime is proposed. The presented method aims to expand existing solutions dealing with varying frequency to a more general solution dealing with independent, simultaneous varying frequency and amplitude of signal components.

  16. Glucose test provenance recording in UK primary care: was that fasted or random?

    Science.gov (United States)

    McGovern, A P; Fieldhouse, H; Tippu, Z; Jones, S; Munro, N; de Lusignan, S

    2017-01-01

    To describe the proportion of glucose tests with unrecorded provenance in routine primary care data and identify the impact on clinical practice. A cross-sectional analysis was conducted of blood glucose measurements from the Royal College of General Practitioner Research and Surveillance Centre database, which includes primary care records from >100 practices across England and Wales. All blood glucose results recorded during 2013 were identified. Tests were grouped by provenance (fasting, oral glucose tolerance test, random, none specified and other). A clinical audit in a single primary care practice was also performed to identify the impact of failing to record glucose provenance on diabetes diagnosis. A total of 2 137 098 people were included in the cross-sectional analysis. Of 203 350 recorded glucose measurements the majority (117 893; 58%) did not have any provenance information. The most commonly reported provenance was fasting glucose (75 044; 37%). The distribution of glucose values where provenance was not recorded was most similar to that of fasting samples. The glucose measurements of 256 people with diabetes in the audit practice (size 11 514 people) were analysed. The initial glucose measurement had no provenance information in 164 cases (64.1%). A clinician questioned the provenance of a result in 41 cases (16.0%); of these, 14 (34.1%) required repeating. Lack of provenance led to delays in the diagnosis of diabetes [median (range) 30 (3-614) days]. The recording of glucose provenance in UK primary care could be improved. Failure to record provenance causes unnecessary repeated testing, delayed diagnosis and wasted clinician time. © 2016 The Authors. Diabetic Medicine published by John Wiley & Sons Ltd on behalf of Diabetes UK.

  17. Tunable Passive Vibration Suppressor

    Science.gov (United States)

    Boechler, Nicholas (Inventor); Dillon, Robert Peter (Inventor); Daraio, Chiara (Inventor); Davis, Gregory L. (Inventor); Shapiro, Andrew A. (Inventor); Borgonia, John Paul C. (Inventor); Kahn, Daniel Louis (Inventor)

    2016-01-01

    An apparatus and method for vibration suppression using a granular particle chain. The granular particle chain is statically compressed and the end particles of the chain are attached to a payload and vibration source. The properties of the granular particles along with the amount of static compression are chosen to provide desired filtering of vibrations.

  18. Vibrations and Eigenvalues

    Indian Academy of Sciences (India)

    We make music by causing strings, membranes, or air columns to vibrate. Engineers design safe structures by control- ling vibrations. I will describe to you a very simple vibrating system and the mathematics needed to analyse it. The ideas were born in the work of Joseph-Louis Lagrange (1736–1813), and I begin by quot-.

  19. The Accuracy of Pass/Fail Decisions in Random and Difficulty-Balanced Domain-Sampling Tests.

    Science.gov (United States)

    Schnipke, Deborah L.

    A common practice in some certification fields (e.g., information technology) is to draw items from an item pool randomly and apply a common passing score, regardless of the items administered. Because these tests are commonly used, it is important to determine how accurate the pass/fail decisions are for such tests and whether fairly small,…

  20. Microelectronics Instrument Products Shock and Vibration Electro-Optics. Section D; Strength Analysis

    Science.gov (United States)

    1994-01-01

    The strength analysis report for FRR shall include only revisions to update the strength analysis reports for the flight design configuration. Since there have been no revisions to the design configuration since the PDR and the CDR this report shall consist of re-submitting the analysis previously performed. In addition the motors have been subjected to Sine vibration, Random vibration, and shock per the SXI specification. Both motor/encoders have passed all three tests. There was no evidence of damage to the motor/encoder and the motor/encoder performed as required by the Acceptance test procedure. No degradation was seen between the before and after performance tests. The testing verified the analysis that there were adequate mf@ty margins with regard to structural integrity. Separate reports are available from the test facility and are apart of the FRR submittal.

  1. Vibration-Based Damage Detection in Beams by Cooperative Coevolutionary Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Kittipong Boonlong

    2014-03-01

    Full Text Available Vibration-based damage detection, a nondestructive method, is based on the fact that vibration characteristics such as natural frequencies and mode shapes of structures are changed when the damage happens. This paper presents cooperative coevolutionary genetic algorithm (CCGA, which is capable for an optimization problem with a large number of decision variables, as the optimizer for the vibration-based damage detection in beams. In the CCGA, a minimized objective function is a numerical indicator of differences between vibration characteristics of the actual damage and those of the anticipated damage. The damage detection in a uniform cross-section cantilever beam, a uniform strength cantilever beam, and a uniform cross-section simply supported beam is used as the test problems. Random noise in the vibration characteristics is also considered in the damage detection. In the simulation analysis, the CCGA provides the superior solutions to those that use standard genetic algorithms presented in previous works, although it uses less numbers of the generated solutions in solution search. The simulation results reveal that the CCGA can efficiently identify the occurred damage in beams for all test problems including the damage detection in a beam with a large number of divided elements such as 300 elements.

  2. Predictive value of testing random urine sample to detect microalbuminuria in diabetic subjects during outpatient visit.

    Science.gov (United States)

    Bouhanick, B; Berrut, G; Chameau, A M; Hallar, M; Bled, F; Chevet, B; Vergely, J; Rohmer, V; Fressinaud, P; Marre, M

    1992-01-01

    The predictive value of random urine sample during outpatient visit to predict persistent microalbuminuria was studied in 76 Type 1, insulin-dependent diabetic subjects, 61 Type 2, non-insulin-dependent diabetic subjects, and 72 Type 2, insulin-treated diabetic subjects. Seventy-six patients attended outpatient clinic during morning, and 133 during afternoon. Microalbuminuria was suspected if Urinary Albumin Excretion (UAE) exceeded 20 mg/l. All patients were hospitalized within 6 months following outpatient visit, and persistent microalbuminuria was assessed then if UAE was between 30 and 300 mg/24 h on 2-3 occasions in 3 urines samples. Of these 209 subjects eighty-three were also screened with Microbumintest (Ames-Bayer), a semi-quantitative method. Among the 209 subjects, 71 were positive both for microalbuminuria during outpatient visit and a persistent microalbuminuria during hospitalization: sensitivity 91.0%, specificity 83.2%, concordance 86.1%, and positive predictive value 76.3% (chi-squared test: 191; p less than 10(-4)). Data were not different for subjects examined on morning, or on afternoon. Among the 83 subjects also screened with Microbumintest, 22 displayed both a positive reaction and a persistent microalbuminuria: sensitivity 76%, specificity 81%, concordance 80%, and positive predictive value 69% (chi-squared test: 126; p less than 10(-4)). Both types of screening appeared equally effective during outpatient visit. Hence, a persistent microalbuminuria can be predicted during an outpatient visit in a diabetic clinic.

  3. Massive-Scale Gene Co-Expression Network Construction and Robustness Testing Using Random Matrix Theory

    Science.gov (United States)

    Isaacson, Sven; Luo, Feng; Feltus, Frank A.; Smith, Melissa C.

    2013-01-01

    The study of gene relationships and their effect on biological function and phenotype is a focal point in systems biology. Gene co-expression networks built using microarray expression profiles are one technique for discovering and interpreting gene relationships. A knowledge-independent thresholding technique, such as Random Matrix Theory (RMT), is useful for identifying meaningful relationships. Highly connected genes in the thresholded network are then grouped into modules that provide insight into their collective functionality. While it has been shown that co-expression networks are biologically relevant, it has not been determined to what extent any given network is functionally robust given perturbations in the input sample set. For such a test, hundreds of networks are needed and hence a tool to rapidly construct these networks. To examine functional robustness of networks with varying input, we enhanced an existing RMT implementation for improved scalability and tested functional robustness of human (Homo sapiens), rice (Oryza sativa) and budding yeast (Saccharomyces cerevisiae). We demonstrate dramatic decrease in network construction time and computational requirements and show that despite some variation in global properties between networks, functional similarity remains high. Moreover, the biological function captured by co-expression networks thresholded by RMT is highly robust. PMID:23409071

  4. FEM Updating of Tall Buildings using Ambient Vibration Data

    DEFF Research Database (Denmark)

    Ventura, C. E.; Lord, J. F.; Turek, M.

    2005-01-01

    Ambient vibration testing is the most economical non-destructive testing method to acquire vibration data from large civil engineering structures. The purpose of this paper is to demonstrate how ambient vibration Modal Identification techniques can be effectively used with Model Updating tools...... and the corresponding mode shapes. The degree of torsional coupling between the modes was also investigated. The modal identification results obtained from ambient vibration measurements of each building were used to update a finite element model of the structure. The starting model of each structure was developed from...... an ambient vibration modal identification....

  5. Comparison of the commercial color LCD and the medical monochrome LCD using randomized object test patterns.

    Science.gov (United States)

    Wu, Jay; Wu, Tung H; Han, Rou P; Chang, Shu J; Shih, Cheng T; Sun, Jing Y; Hsu, Shih M

    2012-01-01

    Workstations and electronic display devices in a picture archiving and communication system (PACS) provide a convenient and efficient platform for medical diagnosis. The performance of display devices has to be verified to ensure that image quality is not degraded. In this study, we designed a set of randomized object test patterns (ROTPs) consisting of randomly located spheres with various image characteristics to evaluate the performance of a 2.5 mega-pixel (MP) commercial color LCD and a 3 MP diagnostic monochrome LCD in several aspects, including the contrast, resolution, point spread effect, and noise. The ROTPs were then merged into 120 abdominal CT images. Five radiologists were invited to review the CT images, and receiver operating characteristic (ROC) analysis was carried out using a five-point rating scale. In the high background patterns of ROTPs, the sensitivity performance was comparable between both monitors in terms of contrast and resolution, whereas, in the low background patterns, the performance of the commercial color LCD was significantly poorer than that of the diagnostic monochrome LCD in all aspects. The average area under the ROC curve (AUC) for reviewing abdominal CT images was 0.717±0.0200 and 0.740±0.0195 for the color monitor and the diagnostic monitor, respectively. The observation time (OT) was 145±27.6 min and 127±19.3 min, respectively. No significant differences appeared in AUC (p = 0.265) and OT (p = 0.07). The overall results indicate that ROTPs can be implemented as a quality control tool to evaluate the intrinsic characteristics of display devices. Although there is still a gap in technology between different types of LCDs, commercial color LCDs could replace diagnostic monochrome LCDs as a platform for reviewing abdominal CT images after monitor calibration.

  6. Comparison of the commercial color LCD and the medical monochrome LCD using randomized object test patterns.

    Directory of Open Access Journals (Sweden)

    Jay Wu

    Full Text Available Workstations and electronic display devices in a picture archiving and communication system (PACS provide a convenient and efficient platform for medical diagnosis. The performance of display devices has to be verified to ensure that image quality is not degraded. In this study, we designed a set of randomized object test patterns (ROTPs consisting of randomly located spheres with various image characteristics to evaluate the performance of a 2.5 mega-pixel (MP commercial color LCD and a 3 MP diagnostic monochrome LCD in several aspects, including the contrast, resolution, point spread effect, and noise. The ROTPs were then merged into 120 abdominal CT images. Five radiologists were invited to review the CT images, and receiver operating characteristic (ROC analysis was carried out using a five-point rating scale. In the high background patterns of ROTPs, the sensitivity performance was comparable between both monitors in terms of contrast and resolution, whereas, in the low background patterns, the performance of the commercial color LCD was significantly poorer than that of the diagnostic monochrome LCD in all aspects. The average area under the ROC curve (AUC for reviewing abdominal CT images was 0.717±0.0200 and 0.740±0.0195 for the color monitor and the diagnostic monitor, respectively. The observation time (OT was 145±27.6 min and 127±19.3 min, respectively. No significant differences appeared in AUC (p = 0.265 and OT (p = 0.07. The overall results indicate that ROTPs can be implemented as a quality control tool to evaluate the intrinsic characteristics of display devices. Although there is still a gap in technology between different types of LCDs, commercial color LCDs could replace diagnostic monochrome LCDs as a platform for reviewing abdominal CT images after monitor calibration.

  7. [What does "p" mean at conclusion of a test of hypothesis in a randomized controlled clinical trial of superiority?].

    Science.gov (United States)

    Marubini, Ettore; Gallo, Fabio; Pizzamiglio, Sara; Verderio, Paolo

    2006-10-01

    The aim of this statistical note, the sixth in the series, is to introduce the rationale of the test of hypothesis suitable for comparing the effect of two treatments in a randomized controlled clinical trial of superiority. The presentation takes advantage of the analogy with a criminal trial debate based upon circumstantial evidence in an Italian Court. The results of three randomized controlled clinical trials: ISIS-1, AIMS and RESTORE are introduced and proper ways for their interpretation are suggested.

  8. Estimation of Genetic Parameters for First Lactation Monthly Test-day Milk Yields using Random Regression Test Day Model in Karan Fries Cattle

    Directory of Open Access Journals (Sweden)

    Ajay Singh

    2016-06-01

    Full Text Available A single trait linear mixed random regression test-day model was applied for the first time for analyzing the first lactation monthly test-day milk yield records in Karan Fries cattle. The test-day milk yield data was modeled using a random regression model (RRM considering different order of Legendre polynomial for the additive genetic effect (4th order and the permanent environmental effect (5th order. Data pertaining to 1,583 lactation records spread over a period of 30 years were recorded and analyzed in the study. The variance component, heritability and genetic correlations among test-day milk yields were estimated using RRM. RRM heritability estimates of test-day milk yield varied from 0.11 to 0.22 in different test-day records. The estimates of genetic correlations between different test-day milk yields ranged 0.01 (test-day 1 [TD-1] and TD-11 to 0.99 (TD-4 and TD-5. The magnitudes of genetic correlations between test-day milk yields decreased as the interval between test-days increased and adjacent test-day had higher correlations. Additive genetic and permanent environment variances were higher for test-day milk yields at both ends of lactation. The residual variance was observed to be lower than the permanent environment variance for all the test-day milk yields.

  9. Factors affecting compliance in faecal occult blood testing: a cluster randomized study of the faecal immunochemical test versus the guaiac faecal occult test.

    Science.gov (United States)

    Birkenfeld, Shlomo; Belfer, Rachel Gingold; Chared, Miri; Vilkin, Alex; Barchana, Micha; Lifshitz, Irena; Fruchter, Dana; Aronski, Dina; Balicer, Ran; Niv, Yaron; Levi, Zohar

    2011-01-01

    To compare the uptake of faecal immunochemical occult blood test (FIT) with guaiac faecal occult blood test (gFOBT) in a screening programme, with specific attention to the demographic and socioeconomic factors that might affect test uptake. The Clalit Health Service screening programme, Israel. Average-risk individuals aged 50-75 years were randomized into a FIT arm or gFOBT arm using a programme based on the socioeconomic status (SES) of their primary care clinics. G-FOBT was performed with Hemoccult SENSA™ (3 evacuations) and FIT with the OC- MICRO(TM) (3 evacuations, refrigerating mandated). The GLIMMIX model was used. There were 5,464 and 10,668 eligible participants in the FIT and gFOBT arms respectively. Compliance in taking the kits was better (but not statistically significantly better) with gFOBT (37.8% vs. 29.3%; odds ratio [OR] 1.43 [95% CI 0.73-2.80]; P = 0.227). Kit return was higher in the FIT arm (65.0% vs. 78.9%; OR 0.45 [95% CI 0.24-0.83], P = 0.021). Overall test uptake was affected by age, gender, being immigrant and SES (determined by whether or not the participant paid national insurance tax, and the SES of the primary care clinic). The overall uptake of gFOBT and FIT was comparable (OR 0.996 [95% CI 0.46-2.17], P = 0.99). Overall compliance for test uptake was comparable between the two methods despite the more demanding procedure in the FIT arm. Sociodemographic parameters were the major determinants of compliance. An educational programme, with emphasis on the sociodemographic characteristics of the target population, should be instigated.

  10. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations. Phase 6-B: Experiments with progressing/regressing forced rotor flapping modes

    Science.gov (United States)

    Hohenemser, K. H.; Crews, S. T.

    1972-01-01

    A two bladed 16-inch hingeless rotor model was built and tested outside and inside a 24 by 24 inch wind tunnel test section at collective pitch settings up to 5 deg and rotor advance ratios up to .4. The rotor model has a simple eccentric mechanism to provide progressing or regressing cyclic pitch excitation. The flapping responses were compared to analytically determined responses which included flap-bending elasticity but excluded rotor wake effects. Substantial systematic deviations of the measured responses from the computed responses were found, which were interpreted as the effects of interaction of the blades with a rotating asymmetrical wake.

  11. Vibration analysis of cryocoolers

    Science.gov (United States)

    Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira; Koyama, Tomohiro; Li, Rui

    2004-05-01

    The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas.

  12. Vibration analysis of cryocoolers

    Energy Technology Data Exchange (ETDEWEB)

    Tomaru, Takayuki; Suzuki, Toshikazu; Haruyama, Tomiyoshi; Shintomi, Takakazu; Yamamoto, Akira [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki (Japan); Koyama, Tomohiro; Rui Li [Sumitomo Heavy Industries Ltd., Tokyo (Japan)

    2004-05-01

    The vibrations of Gifford-McMahon (GM) and pulse-tube (PT) cryocoolers were measured and analyzed. The vibrations of the cold-stage and cold-head were measured separately to investigate their vibration mechanisms. The measurements were performed while maintaining the thermal conditions of the cryocoolers at a steady state. We found that the vibration of the cold-head for the 4 K PT cryocooler was two orders of magnitude smaller than that of the 4 K GM cryocooler. On the other hand, the vibration of the cold-stages for both cryocoolers was of the same order of magnitude. From a spectral analysis of the vibrations and a simulation, we concluded that the vibration of the cold-stage is caused by an elastic deformation of the pulse tubes (or cylinders) due to the pressure oscillation of the working gas. (Author)

  13. Vibration of hydraulic machinery

    CERN Document Server

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

    2013-01-01

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

  14. A randomized trial of the clinical utility of genetic testing for obesity: design and implementation considerations.

    Science.gov (United States)

    Wang, Catharine; Gordon, Erynn S; Stack, Catharine B; Liu, Ching-Ti; Norkunas, Tricia; Wawak, Lisa; Christman, Michael F; Green, Robert C; Bowen, Deborah J

    2014-02-01

    Obesity rates in the United States have escalated in recent decades and present a major challenge in public health prevention efforts. Currently, testing to identify genetic risk for obesity is readily available through several direct-to-consumer companies. Despite the availability of this type of testing, there is a paucity of evidence as to whether providing people with personal genetic information on obesity risk will facilitate or impede desired behavioral responses. We describe the key issues in the design and implementation of a randomized controlled trial examining the clinical utility of providing genetic risk information for obesity. Participants are being recruited from the Coriell Personalized Medicine Collaborative, an ongoing, longitudinal research cohort study designed to determine the utility of personal genome information in health management and clinical decision making. The primary focus of the ancillary Obesity Risk Communication Study is to determine whether genetic risk information added value to traditional communication efforts for obesity, which are based on lifestyle risk factors. The trial employs a 2 × 2 factorial design in order to examine the effects of providing genetic risk information for obesity, alone or in combination with lifestyle risk information, on participants' psychological responses, behavioral intentions, health behaviors, and weight. The factorial design generated four experimental arms based on communication of estimated risk to participants: (1) no risk feedback (control), (2) genetic risk only, (3) lifestyle risk only, and (4) both genetic and lifestyle risk (combined). Key issues in study design pertained to the selection of algorithms to estimate lifestyle risk and determination of information to be provided to participants assigned to each experimental arm to achieve a balance between clinical standards and methodological rigor. Following the launch of the trial in September 2011, implementation challenges

  15. The Effects of Tai Chi Chuan Combined with Vibration Training on Balance Control and Lower Extremity Muscle Power

    Science.gov (United States)

    Chung, Pao-Hung; Lin, Guan-Lun; Liu, Chiang; Chuang, Long-Ren; Shiang, Tzyy-Yuang

    2013-01-01

    The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key points Eight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population. The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism. Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other

  16. The effects of tai chi chuan combined with vibration training on balance control and lower extremity muscle power.

    Science.gov (United States)

    Chung, Pao-Hung; Lin, Guan-Lun; Liu, Chiang; Chuang, Long-Ren; Shiang, Tzyy-Yuang

    2013-01-01

    The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV), a Tai Chi Chuan group (TCC) or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm) three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods. Key pointsEight weeks of Tai Chi Chuan combined with vibration training can more efficiently improve balance control for an untrained young population.The positive training effect on the lower extremity muscle power induced by vibration stimuli during Tai Chi Chuan movements still remains significant because of SSC mechanism.Combining Tai Chi Chuan with vibration training is more efficient and does not decrease the overall training effects due to a cross-interaction of each other.

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

    Directory of Open Access Journals (Sweden)

    Susan A Novotny

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

  18. Effect of multi axis vibration and subject postures on sketching ...

    African Journals Online (AJOL)

    Sedentary activities such as reading, writing, sketching, etc. are affected due to the train vibrations. Therefore, the present study investigates the extent of perceived difficulty and distortion in a sketching task by seated subjects in two postures under low frequency, multi axial random vibrations. Thirty male voluntary subjects ...

  19. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    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

  1. Concepts for a theoretical and experimental study of lifting rotor random loads and vibrations (further experiments with progressing/regressing rotor flapping modes), Phase 7-C

    Science.gov (United States)

    Hohenemser, K. H.; Crews, S. T.

    1973-01-01

    The experiments with progressing/regressing forced rotor flapping modes have been extended in several directions and the data processing method has been considerably refined. The 16 inch hingeless 2-bladed rotor model was equipped with a new set of high precision blades which removed previously encountered tracking difficulties at high advance ratio, so that tests up to .8 rotor advance ratio could be conducted. In addition to data with 1.20 blade natural flapping frequency data at 1.10 flapping frequency were obtained. Outside the wind tunnel, tests with a ground plate located at different distances below the rotor were conducted while recording the dynamic downflow at a station .2R below the rotor plane with a hot wire anemometer.

  2. A Randomized Rounding Approach for Optimization of Test Sheet Composing and Exposure Rate Control in Computer-Assisted Testing

    Science.gov (United States)

    Wang, Chu-Fu; Lin, Chih-Lung; Deng, Jien-Han

    2012-01-01

    Testing is an important stage of teaching as it can assist teachers in auditing students' learning results. A good test is able to accurately reflect the capability of a learner. Nowadays, Computer-Assisted Testing (CAT) is greatly improving traditional testing, since computers can automatically and quickly compose a proper test sheet to meet user…

  3. Randomized test of an implementation intention-based tool to reduce stress-induced eating.

    Science.gov (United States)

    O'Connor, Daryl B; Armitage, Christopher J; Ferguson, Eamonn

    2015-06-01

    Stress may indirectly contribute to disease (e.g. cardiovascular disease, cancer) by producing deleterious changes to diet. The purpose of this study was to test the effectiveness of a stress management support (SMS) tool to reduce stress-related unhealthy snacking and to promote stress-related healthy snacking. Participants were randomized to complete a SMS tool with instruction to link stressful situations with healthy snack alternatives (experimental) or a SMS tool without a linking instruction (control). On-line daily reports of stressors and snacking were completed for 7 days. Daily stressors were associated with unhealthy snack consumption in the control condition but not in the experimental condition. Participants highly motivated towards healthy eating consumed a greater number of healthy snacks in the experimental condition on stressful days compared to participants in the experimental condition with low and mean levels of motivation. This tool is an effective, theory driven, intervention that helps to protect against stress-induced high-calorie snack consumption.

  4. Free Vibration of Uncertain Unsymmetrically Laminated Beams

    Science.gov (United States)

    Kapania, Rakesh K.; Goyal, Vijay K.

    2001-01-01

    Monte Carlo Simulation and Stochastic FEA are used to predict randomness in the free vibration response of thin unsymmetrically laminated beams. For the present study, it is assumed that randomness in the response is only caused by uncertainties in the ply orientations. The ply orientations may become random or uncertain during the manufacturing process. A new 16-dof beam element, based on the first-order shear deformation beam theory, is used to study the stochastic nature of the natural frequencies. Using variational principles, the element stiffness matrix and mass matrix are obtained through analytical integration. Using a random sequence a large data set is generated, containing possible random ply-orientations. This data is assumed to be symmetric. The stochastic-based finite element model for free vibrations predicts the relation between the randomness in fundamental natural frequencies and the randomness in ply-orientation. The sensitivity derivatives are calculated numerically through an exact formulation. The squared fundamental natural frequencies are expressed in terms of deterministic and probabilistic quantities, allowing to determine how sensitive they are to variations in ply angles. The predicted mean-valued fundamental natural frequency squared and the variance of the present model are in good agreement with Monte Carlo Simulation. Results, also, show that variations between plus or minus 5 degrees in ply-angles can affect free vibration response of unsymmetrically and symmetrically laminated beams.

  5. Long-range vibration sensor based on correlation analysis of optical frequency-domain reflectometry signals.

    Science.gov (United States)

    Ding, Zhenyang; Yao, X Steve; Liu, Tiegen; Du, Yang; Liu, Kun; Han, Qun; Meng, Zhuo; Chen, Hongxin

    2012-12-17

    We present a novel method to achieve a space-resolved long- range vibration detection system based on the correlation analysis of the optical frequency-domain reflectometry (OFDR) signals. By performing two separate measurements of the vibrated and non-vibrated states on a test fiber, the vibration frequency and position of a vibration event can be obtained by analyzing the cross-correlation between beat signals of the vibrated and non-vibrated states in a spatial domain, where the beat signals are generated from interferences between local Rayleigh backscattering signals of the test fiber and local light oscillator. Using the proposed technique, we constructed a standard single-mode fiber based vibration sensor that can have a dynamic range of 12 km and a measurable vibration frequency up to 2 kHz with a spatial resolution of 5 m. Moreover, preliminarily investigation results of two vibration events located at different positions along the test fiber are also reported.

  6. Impact of using a local protocol in preoperative testing: blind randomized clinical trial.

    Science.gov (United States)

    Santos, Mônica Loureiro; Iglesias, Antônio Carlos

    2017-01-01

    to evaluate the impact of the use of a local protocol of preoperative test requests in reducing the number of exams requested and in the occurrence of changes in surgical anesthetic management and perioperative complications. we conducted a randomized, blinded clinical trial at the Gaffrée and Guinle University Hospital with 405 patients candidates for elective surgery randomly divided into two groups, according to the practice of requesting preoperative exams: a group with non-selectively requested exams and a protocol group with exams requested according to the study protocol. Studied exams: complete blood count, coagulogram, glycemia, electrolytes, urea and creatinine, ECG and chest X-ray. Primary outcomes: changes in surgical anesthetic management caused by abnormal exams, reduction of the number of exams requested after the use of the protocol and perioperative complications. there was a significant difference (pradiografia de tórax. Desfechos primários: alterações na conduta anestésico-cirúrgica motivadas por exames anormais, redução do número de exames solicitados após o uso do protocolo e complicações perioperatórias. foi observada diferença significativa (p<0,001) no número de exames com resultados alterados entre os dois grupos (14,9% x 29,1%) e redução de 57,3% no número de exames pedidos entre os dois grupos (p<0,001), mais acentuada nos pacientes de menor faixa etária, ASA I, sem doenças associadas e submetidos a procedimentos de menor porte. Não houve diferença significativa na frequência de alterações de conduta motivada por resultado de exames, nem de complicações entre os dois grupos. Na análise multivariada hemograma e coagulograma foram os únicos exames capazes de modificar a conduta anestésico-cirúrgica. o protocolo proposto foi efetivo em eliminar um quantitativo significativo de exames complementares sem indicação clínica, sem que houvesse aumento na morbidade e mortalidades perioperatórias.

  7. WWC Quick Review of the Article "Outcomes of a Prospective Trial of Student-Athlete Drug Testing: The Student Athlete Testing Using Random Notification ('SATURN') Study"

    Science.gov (United States)

    What Works Clearinghouse, 2008

    2008-01-01

    This study examines whether the Student Athlete Testing Using Random Notification ("SATURN") program affects illicit drug and alcohol use among student athletes. The study experienced high rates of sample attrition. Seven of the 18 study schools (39%) left the study and were not included in the analysis. Some students at the remaining…

  8. Effects of whole-body vibration training on fibrinolytic and coagulative factors in healthy young men

    Directory of Open Access Journals (Sweden)

    Farshad Ghazalian

    2014-01-01

    Full Text Available Background: The aim was to evaluate effects of 5-week whole body vibration (WBV training with different amplitudes and progressive frequencies on fibrinolytic/coagulative factors. Materials and Methods: 25 subjects were divided randomly in high or low-amplitude vibration, and control groups. Training consisted of 5-week WBV with amplitudes 4 or 2 mm. Plasma samples were analyzed before and after training. Statistical analysis was done using one-way analysis of variance and Wilcoxon signed ranked test. P <0.05 was considered significant. Results: High-amplitude vibration caused an increase in tissue plasminogen activator (tPA (P = 0.028 (pretest: 1744.61 ± 707.95; posttest: 2313.63 ± 997.19 pg/ml, and decrease in plasminogen activator inhibitor-1 (PAI-1 (P = 0.033 (pretest: 97.94 ± 34.37; posttest: 85.12 ± 36.92 ng/ml. Fibrinogen and plasminogen were not changed significantly. Low-amplitude vibration caused an increase in tPA (P = 0.006 (pretest: 2208.18 ± 1280.37; posttest: 3492.72 ± 3549.22 pg/ml. PAI-1, fibrinogen and plasminogen were not changed significantly. There were no significant differences between groups. Conclusion: Amplitude of vibrations in WBV training may affect fibrinolytic factors.

  9. Sodium bicarbonate ingestion improves Yo-Yo intermittent recovery test 1 performance: a randomized crossover trial

    Directory of Open Access Journals (Sweden)

    Dixon H

    2017-04-01

    Full Text Available Helen Dixon,1 Catherine E Baker,2 Julien S Baker,3 Susan Dewhurst,4 Lawrence D Hayes4 1School of Human Sciences, London Metropolitan University, London, 2English Institute of Sport, Bisham Abbey National Sports Center, Buckinghamshire, 3Institute of Clinical Exercise and Health Science, University of the West of Scotland, Hamilton, 4Department of Medical and Sport Sciences, University of Cumbria, Lancaster, UK Abstract: This study investigated the effect of sodium bicarbonate (NaHCO3– ingestion on the Yo-Yo intermittent recovery test 1 (IR1. We tested the hypothesis that acute ingestion of NaHCO3– would increase blood lactate concentrations [BLa], enhance performance, and reduce rating of perceived exertion (RPE in the Yo-Yo IR1. Eight recreationally active males (N=8, age: 26±4 yr, height: 178±6 cm, body mass: 82±10 kg participated in the Yo-Yo IR1 on two separate occasions, separated by 1 wk, in a randomized crossover design. Following familiarization, during seated rest, participants’ pretest [BLa] was taken, and participants then consumed either a placebo of 0.3 g·kg–1 body weight sodium chloride or 0.3 g·kg–1 body weight NaHCO3–. Sixty minutes postingestion, a standardized warm-up preceded the Yo-Yo IR1. Upon completion, postexercise [BLa] (mmol·L–1, RPE (arbitrary units and Yo-Yo IR1 time to fatigue (s were recorded. Paired t-test revealed a small but significant improvement in Yo-Yo IR1 performance under the NaHCO3– condition (610±267 sec, compared to the placebo condition (556±259 sec; p=0.01; Cohen’s d=0.20. [BLa] increased more under the NaHCO3– condition (1.6±0.7 to 17.5±5.2 mmol·L–1; p<0.001; Cohen’s d=4.29, compared to the placebo condition (2.0±0.7 to 11.5±5.0 mmol·L–1; p=0.001; Cohen’s d=2.66. Postexercise RPE was not significantly different between conditions. The results of this study suggest that acute NaHCO3– ingestion improves Yo-Yo IR1 performance without altering RPE, likely

  10. The effect of the training with the different combinations of frequency and peak-to-peak vibration displacement of whole-body vibration on the strength of knee flexors and extensors

    Directory of Open Access Journals (Sweden)

    M Stania

    2017-01-01

    Full Text Available Whole-body vibration training has become a popular method used in sports and physiotherapy. The study aimed to evaluate the effect of different vibration frequency and peak-to-peak displacement combinations on men knee flexors and extensors strength in isokinetic conditions. The sample consisted of 49 male subjects randomly allocated to seven comparative groups, six of which exercised on a vibration platform with parameters set individually for the groups. The experimental groups were exposed to vibrations 3 times a week for 4 weeks. The pre- and post- isokinetic strength tests, with the angular velocities of 240°/s and 30°/s, were recorded prior to and 2 days after the training. After 4 weeks of whole-body vibration training, a significant increase was noted regarding the mean values of peak torque, average peak torque and total work for knee flexors at high angular velocity in Groups I (60 Hz/ 4 mm and V (40 Hz/ 2 mm (p<0.05. The mean percentage values of post-training changes to study parameters suggest that the training had the most beneficial effect in Groups I (60 Hz/4 mm and IV (60 Hz/2 mm (p<0.05. Whole-body vibrations during static exercise beneficially affected knee flexor strength profile in young men at high angular velocity. The combinations of 60 Hz/4 mm seem to have the most advantageous effects on muscle strength parameters.

  11. Whole body vibration as an adjunct to static stretching.

    Science.gov (United States)

    Feland, J B; Hawks, M; Hopkins, J T; Hunter, I; Johnson, A W; Eggett, D L

    2010-08-01

    This study was a randomized control trial. The purpose of this study was twofold: 1) to determine if stretching the hamstrings during whole-body-vibration (WBV) is more effective than static stretching alone; and 2) to monitor retention of flexibility changes. The main outcome measure was hamstring flexibility as measured in degrees using a passive knee extension test. Thirty-four recreationally active college-age subjects (23.4+/-1.7 yrs) completed this study (22 males, 12 females, avg. ht.=175.6+/-6.4 cm, avg. wt.=74.9+/-11.8 kg). Subjects were assigned to a control group (C), a static stretch group (SS), or a vibration + static stretch group (V). Subjects stretched 5 days/wk for 4-weeks and were followed for 3-weeks after cessation to monitor retention. Analysis showed a significant difference between treatment groups (pstretching for the SS and V groups respectively. Three-week follow-up showed SS returning to baseline with V group still 6.4 degrees (11%+/-3.88% (SEM)) more flexible than at baseline. Stretching concurrently with vibration on a WBV platform appears to be a good adjunct to static stretching with the potential to enhance retention of flexibility gains. (c) Georg Thieme Verlag KG Stuttgart . New York.

  12. THE EFFECTS OF TAI CHI CHUAN COMBINED WITH VIBRATION TRAINING ON BALANCE CONTROL AND LOWER EXTREMITY MUSCLE POWER

    Directory of Open Access Journals (Sweden)

    Pao-Hung Chung

    2013-03-01

    Full Text Available The aim of this study was to determine whether performing Tai Chi Chuan on a customized vibration platform could enhance balance control and lower extremity muscle power more efficiently than Tai Chi Chuan alone in an untrained young population. Forty-eight healthy young adults were randomly assigned to the following three groups: a Tai Chi Chuan combined with vibration training group (TCV, a Tai Chi Chuan group (TCC or a control group. The TCV group underwent 30 minutes of a reformed Tai Chi Chuan program on a customized vibration platform (32 Hz, 1 mm three times a week for eight weeks, whereas the TCC group was trained without vibration stimuli. A force platform was used to measure the moving area of a static single leg stance and the heights of two consecutive countermovement jumps. The activation of the knee extensor and flexor was also measured synchronously by surface electromyography in all tests. The results showed that the moving area in the TCV group was significantly decreased by 15.3%. The second jump height in the TCV group was significantly increased by 8.14%, and the activation of the knee extensor/flexor was significantly decreased in the first jump. In conclusion, Tai Chi Chuan combined with vibration training can more efficiently improve balance control, and the positive training effect on the lower extremity muscle power induced by vibration stimuli still remains significant because there is no cross-interaction between the two different types of training methods.

  13. A randomized controlled trial to test the effectiveness of an immersive 3D video game for anxiety prevention among adolescents

    NARCIS (Netherlands)

    Scholten, H.; Malmberg, M.; Lobel, A.M.; Engels, R.C.M.E.; Granic, I.

    2016-01-01

    Adolescent anxiety is debilitating, the most frequently diagnosed adolescent mental health problem, and leads to substantial long-term problems. A randomized controlled trial (n = 138) was conducted to test the effectiveness of a biofeedback video game (Dojo) for adolescents with elevated levels of

  14. Block design allowed for control of the Hawthorne effect in a randomized controlled trial of test ordering

    NARCIS (Netherlands)

    Verstappen, Wim H. J. M.; van der Weijden, Trudy; ter Riet, Gerben; Grimshaw, Jeremy; Winkens, Ron; Grol, Richard P. T. M.

    2004-01-01

    Background and Objective: To evaluate the value of balanced incomplete block designs in quality improvement research, and their capacity to control for the Hawthorne effect. Methods: General practitioners teams were randomized into three arms and received an intervention on test ordering, relating

  15. Block design allowed for control of the Hawthorne effect in a randomized controlled trial of test ordering.

    NARCIS (Netherlands)

    Verstappen, W.H.; Weijden, T. van der; Riet, G. ter; Grimshaw, J.; Winkens, R.; Grol, R.P.T.M.

    2004-01-01

    BACKGROUND AND OBJECTIVE: To evaluate the value of balanced incomplete block designs in quality improvement research, and their capacity to control for the Hawthorne effect. METHODS: General practitioners teams were randomized into three arms and received an intervention on test ordering, relating

  16. Pseudo-Gaussian and rank-based optimal tests for random individual effects in large n small T panels

    NARCIS (Netherlands)

    Bennala, N.; Hallin, M.; Paindaveine, D.

    2012-01-01

    We consider the problem of detecting unobserved heterogeneity, that is, the problem of testing the absence of random individual effects in an n × T panel. We establish a local asymptotic normality property–with respect to intercept, regression coefficient, the scale parameter σ of the error, and the

  17. Randomized controlled trial of supervised patient self-testing of warfarin therapy using an internet-based expert system.

    LENUS (Irish Health Repository)

    Ryan, F

    2009-08-01

    Increased frequency of prothrombin time testing, facilitated by patient self-testing (PST) of the International Normalized Ratio (INR) can improve the clinical outcomes of oral anticoagulation therapy (OAT). However, oversight of this type of management is often difficult and time-consuming for healthcare professionals. This study reports the first randomized controlled trial of an automated direct-to-patient expert system, enabling remote and effective management of patients on OAT.

  18. SAR-based change detection using hypothesis testing and Markov random field modelling

    Science.gov (United States)

    Cao, W.; Martinis, S.

    2015-04-01

    The objective of this study is to automatically detect changed areas caused by natural disasters from bi-temporal co-registered and calibrated TerraSAR-X data. The technique in this paper consists of two steps: Firstly, an automatic coarse detection step is applied based on a statistical hypothesis test for initializing the classification. The original analytical formula as proposed in the constant false alarm rate (CFAR) edge detector is reviewed and rewritten in a compact form of the incomplete beta function, which is a builtin routine in commercial scientific software such as MATLAB and IDL. Secondly, a post-classification step is introduced to optimize the noisy classification result in the previous step. Generally, an optimization problem can be formulated as a Markov random field (MRF) on which the quality of a classification is measured by an energy function. The optimal classification based on the MRF is related to the lowest energy value. Previous studies provide methods for the optimization problem using MRFs, such as the iterated conditional modes (ICM) algorithm. Recently, a novel algorithm was presented based on graph-cut theory. This method transforms a MRF to an equivalent graph and solves the optimization problem by a max-flow/min-cut algorithm on the graph. In this study this graph-cut algorithm is applied iteratively to improve the coarse classification. At each iteration the parameters of the energy function for the current classification are set by the logarithmic probability density function (PDF). The relevant parameters are estimated by the method of logarithmic cumulants (MoLC). Experiments are performed using two flood events in Germany and Australia in 2011 and a forest fire on La Palma in 2009 using pre- and post-event TerraSAR-X data. The results show convincing coarse classifications and considerable improvement by the graph-cut post-classification step.

  19. [Training in iterative hypothesis testing as part of psychiatric education. A randomized study].

    Science.gov (United States)

    Lampen-Imkamp, S; Alte, C; Sipos, V; Kordon, A; Hohagen, F; Schweiger, U; Kahl, K G

    2012-01-01

    The improvement of medical education is at the center of efforts to reform the studies of medicine. Furthermore, an excellent teaching program for students is a quality feature of medical universities. Besides teaching of disease-specific contents, the acquisition of interpersonal and decision-making skills is important. However, the cognitive style of senior physicians leading to a diagnosis cannot easily be taught. Therefore, the following study aimed at examining whether specific training in iterative hypothesis testing (IHT) may improve the correctness of the diagnostic process. Seventy-one medical students in their 9th-11th terms were randomized to medical teaching as usual or to IHT training for 4 weeks. The intervention group received specific training according to the method of IHT. All students were examined by a multiple choice (MC) exam and additionally by simulated patients (SP). The SPs were instructed to represent either a patient with depression and comorbid anxiety and substance use disorder (SP1) or to represent a patient with depression, obsessive-compulsive disorder and acute suicidal tendencies (SP2). All students identified the diagnosis of major depression in the SPs, but IHT-trained students recognized more diagnostic criteria. Furthermore, IHT-trained students recognized acute suicide tendencies in SP2 more often and identified more comorbid psychiatric disorders. The results of the MC exam were comparable in both groups. An analysis of the satisfaction with the different training programs revealed that the IHT training received a better appraisal. Our results point to the role of IHT in teaching diagnostic skills. However, the results of the MC exam were not influenced by IHT training. Furthermore, our results show that students are in need of training in practical clinical skills.

  20. Crowdsourcing to promote HIV testing among MSM in China: study protocol for a stepped wedge randomized controlled trial.

    Science.gov (United States)

    Tucker, Joseph D

    2017-10-02

    HIV testing for marginalized populations is critical to controlling the HIV epidemic. However, the HIV testing rate among men who have sex with men (MSM) in China remains low. Crowdsourcing, the process of shifting individual tasks to a group, has been increasingly adopted in public health programs and may be a useful tool for spurring innovation in HIV testing campaigns. We designed a multi-site study to develop a crowdsourced HIV test promotion campaign and evaluate its effectiveness against conventional campaigns among MSM in China. This study will use an adaptation of the stepped wedge, randomized controlled trial design. A total of eight major metropolitan cities in China will be randomized to sequentially initiate interventions at 3-month intervals. The intervention uses crowdsourcing at multiple steps to sustain crowd contribution. Approximately 1280 MSM, who are 16 years of age or over, live in the intervention city, have not been tested for HIV in the past 3 months, and are not living with HIV, will be recruited. Recruitment will take place through banner advertisements on a large gay dating app along with other social media platforms. Participants will complete one follow-up survey every 3 months for 12 months to evaluate their HIV testing uptake in the past 3 months and secondary outcomes including syphilis testing, sex without condoms, community engagement, testing stigma, and other related outcomes. MSM HIV testing rates remain poor in China. Innovative methods to promote HIV testing are urgently needed. With a large-scale, stepped wedge, randomized controlled trial our study can improve understanding of crowdsourcing's long-term effectiveness in public health campaigns, expand HIV testing coverage among a key population, and inform intervention design in related public health fields. ClinicalTrials.gov, NCT02796963 . Registered on 23 May 2016.

  1. Vibrational damping of composite materials

    Science.gov (United States)

    Biggerstaff, Janet M.

    The purpose of this research was to develop new methods of vibrational damping in polymeric composite materials along with expanding the knowledge of currently used vibrational damping methods. A new barrier layer technique that dramatically increased damping in viscoelastic damping materials that interacted with the composite resin was created. A method for testing the shear strength of damping materials cocured in composites was developed. Directional damping materials, where the loss factor and modulus could be tailored by changing the angle, were produced and investigated. The addition of particles between composite prepreg layers to increase damping was studied. Electroviscoelastic materials that drastically changed properties such as loss factor and modulus with an applied voltage were manufactured and tested.

  2. The Effect of Fatigue on Upper Quarter Y-Balance Test Scores in Recreational Weightlifters: A Randomized Controlled Trial.

    Science.gov (United States)

    Salo, Trenton D; Chaconas, Eric

    2017-04-01

    A paucity of research currently exists for upper extremity return to sport testing. The Upper Quarter Y-Balance Test (YBT-UQ) is a clinical test of closed kinetic chain performance with demonstrated reliability. Prior investigations of the YBT-UQ were conducted with individuals in a resting state and no comparison to performance in a fatigued state has been conducted. To examine the effect of upper extremity fatigue on the performance of the YBT-UQ in recreational weightlifters. Randomized controlled trial. 24 participants who participated in recreational weight training three days per week were randomly allocated to a control or experimental group. Individuals in the control group were tested using the YBT-UQ and re-tested after a 20-minute rest period. Participants in the experimental group were tested with the YBT-UQ, performed an upper extremity exercise fatigue protocol, and immediately re-tested. Examiners were blinded to participant allocation. Differences from pre- to post-fatigue YBT-UQ testing revealed score reductions between 2.04cm - 12.16cm for both composite scores and individual reach directions. The repeated measures ANOVA revealed significant differences when comparing the pre- and post-testing results between the fatigue and non-fatigue groups for all individual directions (p ≤ .006) and composite scores both limbs (p<.035). The performance of an upper body fatigue protocol significantly reduces YBT-UQ scores in recreational weightlifters. 1b.

  3. RESEARCH OF BRIDGE STRUCTURE VIBRATION CHARACTERISTICS

    Directory of Open Access Journals (Sweden)

    V.P. Babak

    2005-02-01

    Full Text Available  Bridge structure test results with using different types of dynamic force have been considered. It has been shown, that the developed technique of registering and processing vibration signals allows obtaining thin spectrum structure. The analysis of its change that is defined by the type of structure loading applied has been carried out. Key parameters of the vibration signals registered have been defined.

  4. Data Management Techniques for Blade Vibration Analysis

    Directory of Open Access Journals (Sweden)

    Przysowa Radosław

    2016-07-01

    Full Text Available Well-designed procedures are required to handle large amounts of data, generated by complex measurement systems used in engine tests. The paper presents selected methodologies and software tools for characterisation and monitoring of blade vibration. Common file formats and data structures as well as methods to process and visualise tip-timing data are discussed. Report Generation Framework (RGF developed in Python is demonstrated as a flexible tool for processing and publishing blade vibration results.

  5. Safety and Efficacy Assessment of Two New Leprosy Skin Test Antigens: Randomized Double Blind Clinical Study

    Science.gov (United States)

    Rivoire, Becky L.; Groathouse, Nathan A.; TerLouw, Stephen; Neupane, Kapil Dev; Ranjit, Chaman; Sapkota, Bishwa Raj; Khadge, Saraswoti; Kunwar, Chatra B.; Macdonald, Murdo; Hawksworth, Rachel; Thapa, Min B.; Hagge, Deanna A.; Tibbals, Melinda; Smith, Carol; Dube, Tina; She, Dewei; Wolff, Mark; Zhou, Eric; Makhene, Mamodikoe; Mason, Robin; Sizemore, Christine; Brennan, Patrick J.

    2014-01-01

    Background New tools are required for the diagnosis of pre-symptomatic leprosy towards further reduction of disease burden and its associated reactions. To address this need, two new skin test antigens were developed to assess safety and efficacy in human trials. Methods A Phase I safety trial was first conducted in a non-endemic region for leprosy (U.S.A.). Healthy non-exposed subjects (n = 10) received three titrated doses (2.5 µg, 1.0 µg and 0.1 µg) of MLSA-LAM (n = 5) or MLCwA (n = 5) and control antigens [Rees MLSA (1.0 µg) and saline]. A randomized double blind Phase II safety and efficacy trial followed in an endemic region for leprosy (Nepal), but involved only the 1.0 µg (high dose) and 0.1 µg (low dose) of each antigen; Tuberculin PPD served as a control antigen. This Phase II safety and efficacy trial consisted of three Stages: Stage A and B studies were an expansion of Phase I involving 10 and 90 subjects respectively, and Stage C was then conducted in two parts (high dose and low dose), each enrolling 80 participants: 20 borderline lepromatous/lepromatous (BL/LL) leprosy patients, 20 borderline tuberculoid/tuberculoid (BT/TT) leprosy patients, 20 household contacts of leprosy patients (HC), and 20 tuberculosis (TB) patients. The primary outcome measure for the skin test was delayed type hypersensitivity induration. Findings In the small Phase I safety trial, reactions were primarily against the 2.5 µg dose of both antigens and Rees control antigen, which were then excluded from subsequent studies. In the Phase II, Stage A/B ramped-up safety study, 26% of subjects (13 of 50) showed induration against the high dose of each antigen, and 4% (2 of 50) reacted to the low dose of MLSA-LAM. Phase II, Stage C safety and initial efficacy trial showed that both antigens at the low dose exhibited low sensitivity at 20% and 25% in BT/TT leprosy patients, but high specificity at 100% and 95% compared to TB patients. The high dose of both antigens

  6. Safety and efficacy assessment of two new leprosy skin test antigens: randomized double blind clinical study.

    Directory of Open Access Journals (Sweden)

    Becky L Rivoire

    Full Text Available New tools are required for the diagnosis of pre-symptomatic leprosy towards further reduction of disease burden and its associated reactions. To address this need, two new skin test antigens were developed to assess safety and efficacy in human trials.A Phase I safety trial was first conducted in a non-endemic region for leprosy (U.S.A.. Healthy non-exposed subjects (n = 10 received three titrated doses (2.5 µg, 1.0 µg and 0.1 µg of MLSA-LAM (n = 5 or MLCwA (n = 5 and control antigens [Rees MLSA (1.0 µg and saline]. A randomized double blind Phase II safety and efficacy trial followed in an endemic region for leprosy (Nepal, but involved only the 1.0 µg (high dose and 0.1 µg (low dose of each antigen; Tuberculin PPD served as a control antigen. This Phase II safety and efficacy trial consisted of three Stages: Stage A and B studies were an expansion of Phase I involving 10 and 90 subjects respectively, and Stage C was then conducted in two parts (high dose and low dose, each enrolling 80 participants: 20 borderline lepromatous/lepromatous (BL/LL leprosy patients, 20 borderline tuberculoid/tuberculoid (BT/TT leprosy patients, 20 household contacts of leprosy patients (HC, and 20 tuberculosis (TB patients. The primary outcome measure for the skin test was delayed type hypersensitivity induration.In the small Phase I safety trial, reactions were primarily against the 2.5 µg dose of both antigens and Rees control antigen, which were then excluded from subsequent studies. In the Phase II, Stage A/B ramped-up safety study, 26% of subjects (13 of 50 showed induration against the high dose of each antigen, and 4% (2 of 50 reacted to the low dose of MLSA-LAM. Phase II, Stage C safety and initial efficacy trial showed that both antigens at the low dose exhibited low sensitivity at 20% and 25% in BT/TT leprosy patients, but high specificity at 100% and 95% compared to TB patients. The high dose of both antigens showed lower specificity (70% and 60

  7. Safety and efficacy assessment of two new leprosy skin test antigens: randomized double blind clinical study.

    Science.gov (United States)

    Rivoire, Becky L; Groathouse, Nathan A; TerLouw, Stephen; Neupane, Kapil Dev; Ranjit, Chaman; Sapkota, Bishwa Raj; Khadge, Saraswoti; Kunwar, Chhatra B; Kunwar, Chatra B; Macdonald, Murdo; Hawksworth, Rachel; Thapa, Min B; Hagge, Deanna A; Tibbals, Melinda; Smith, Carol; Dube, Tina; She, Dewei; Wolff, Mark; Zhou, Eric; Makhene, Mamodikoe; Mason, Robin; Sizemore, Christine; Brennan, Patrick J

    2014-01-01

    New tools are required for the diagnosis of pre-symptomatic leprosy towards further reduction of disease burden and its associated reactions. To address this need, two new skin test antigens were developed to assess safety and efficacy in human trials. A Phase I safety trial was first conducted in a non-endemic region for leprosy (U.S.A.). Healthy non-exposed subjects (n = 10) received three titrated doses (2.5 µg, 1.0 µg and 0.1 µg) of MLSA-LAM (n = 5) or MLCwA (n = 5) and control antigens [Rees MLSA (1.0 µg) and saline]. A randomized double blind Phase II safety and efficacy trial followed in an endemic region for leprosy (Nepal), but involved only the 1.0 µg (high dose) and 0.1 µg (low dose) of each antigen; Tuberculin PPD served as a control antigen. This Phase II safety and efficacy trial consisted of three Stages: Stage A and B studies were an expansion of Phase I involving 10 and 90 subjects respectively, and Stage C was then conducted in two parts (high dose and low dose), each enrolling 80 participants: 20 borderline lepromatous/lepromatous (BL/LL) leprosy patients, 20 borderline tuberculoid/tuberculoid (BT/TT) leprosy patients, 20 household contacts of leprosy patients (HC), and 20 tuberculosis (TB) patients. The primary outcome measure for the skin test was delayed type hypersensitivity induration. In the small Phase I safety trial, reactions were primarily against the 2.5 µg dose of both antigens and Rees control antigen, which were then excluded from subsequent studies. In the Phase II, Stage A/B ramped-up safety study, 26% of subjects (13 of 50) showed induration against the high dose of each antigen, and 4% (2 of 50) reacted to the low dose of MLSA-LAM. Phase II, Stage C safety and initial efficacy trial showed that both antigens at the low dose exhibited low sensitivity at 20% and 25% in BT/TT leprosy patients, but high specificity at 100% and 95% compared to TB patients. The high dose of both antigens showed lower specificity (70% and 60

  8. Bevel Gearbox Fault Diagnosis using Vibration Measurements

    Directory of Open Access Journals (Sweden)

    Hartono Dennis

    2016-01-01

    Full Text Available The use of vibration measurementanalysis has been proven to be effective for gearbox fault diagnosis. However, the complexity of vibration signals observed from a gearbox makes it difficult to accurately detectfaults in the gearbox. This work is based on a comparative studyof several time-frequency signal processing methods that can be used to extract information from transient vibration signals containing useful diagnostic information. Experiments were performed on a bevel gearbox test rig using vibration measurements obtained from accelerometers. Initially, thediscrete wavelet transform was implementedfor vibration signal analysis to extract the frequency content of signal from the relevant frequency region. Several time-frequency signal processing methods werethen incorporated to extract the fault features of vibration signals and their diagnostic performances were compared. It was shown thatthe Short Time Fourier Transform (STFT could not offer a good time resolution to detect the periodicity of the faulty gear tooth due the difficulty in choosing an appropriate window length to capture the impulse signal. The Continuous Wavelet Transform (CWT, on the other hand, was suitable to detection of vibration transients generated by localized fault from a gearbox due to its multi-scale property. However, both methods still require a thorough visual inspection. In contrast, it was shown from the experiments that the diagnostic method using the Cepstrumanalysis could provide a direct indication of the faulty tooth without the need of a thorough visual inspection as required by CWT and STFT.

  9. DOWNHOLE VIBRATION MONITORING & CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Martin E. Cobern

    2006-01-17

    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, which entailed modeling and design of the necessary subsystems and design, manufacture and test of a full laboratory prototype, was completed on May 31, 2004. The principal objectives of Phase II are: more extensive laboratory testing, including the evaluation of different feedback algorithms for control of the damper; design and manufacture of a field prototype system; and, testing of the field prototype in drilling laboratories and test wells. Work during this quarter centered on the testing of the rebuilt laboratory prototype and its conversion into a version that will be operable in the drilling tests at TerraTek Laboratories. In addition, formations for use in these tests were designed and constructed, and a test protocol was developed. The change in scope and no-cost extension of Phase II to January, 2006, described in our last report, were approved. The tests are scheduled to be run during the week of January 23, and should be completed before the end of the month.

  10. Damage monitoring and impact detection using optical fiber vibration sensors

    Science.gov (United States)

    Yang, Y. C.; Han, K. S.

    2002-06-01

    Intensity-based optical fiber vibrations sensors (OFVSs) are used in damage monitoring of fiber-reinforced plastics, in vibration sensing, and location of impacts. OFVSs were constructed by placing two cleaved fiber ends in a capillary tube. This sensor is able to monitor structural vibrations. For vibration sensing, the optical fiber sensor was mounted on the carbon fiber reinforced composite beam, and its response was investigated for free and forced vibration. For locating impact points, four OFVSs were placed at chosen positions and the different arrival times of impact-generated vibration signals were recorded. The impact location can be determined from these time delays. Indentation and tensile tests were performed with the measurement of the optical signal and acoustic emission (AE). The OFVSs accurately detected both free and forced vibration signals. Accurate locations of impact were determined on an acrylate plate. It was found that damage information, comparable in quality to AE data, could be obtained from the OFVS signals.

  11. Noise and Vibration Modeling for Anti-Lock Brake Systems

    Science.gov (United States)

    Zhan, Wei

    A new methodology is proposed for noise and vibration analysis for Anti-Lock Brake Systems (ABS). First, a correlation between noise and vibration measurement data and simulation results need to be established. This relationship allows the engineers to focus on modeling and simulation instead of noise and vibration testing. A comprehensive ABS model is derived for noise and vibration study. The model can be set up to do different types of simulations for noise and vibration analysis. If some data is available from actual testing, then the test data can be easily imported into the model as an input to replace the corresponding part in the model. It is especially useful when the design needs to be modified, or trade-off between ABS performance and noise and vibration is necessary. The model can greatly reduce the time to market for ABS products. It also makes system level optimization possible.

  12. Low resonance frequency vibration affects strength of paretic and non-paretic leg differently in patients with stroke.

    Science.gov (United States)

    Tihanyi, J; Di Giminiani, R; Tihanyi, T; Gyulai, G; Trzaskoma, L; Horváth, M

    2010-06-01

    The objective of the study was to investigate the chronic effect of low frequency whole body vibration (WBV) on isometric and eccentric strength of knee extensors with different force exertion capacity. It was hypothesized that (1) four-week WBV intervention with the low frequency domain would enhance muscle strength and (2) the improvement would be more pronounced in the weaker muscle. To test our hypothesis twenty patients with acute stroke were recruited. Ten patients were randomly assigned to vibration and the remaining ten patients served for control.The patients in the vibration group received WBV with 20 Hz frequency three times per week standing on a vibration platform in half squat position meanwhile flexing and extending the joints and placing the weight from one leg to the other. Knee extensor strength was determined under isometric and eccentric contraction before and after WBV intervention. Myoelectrical activity (EMG) of the vastus lateralis muscle was also measured.Significant improvement was revealed in the vibration group only. The maximum isometric torque and EMG activity increased significantly for both paretic and non-paretic leg, but the improvement was threefold greater in the vibration group. No significant alteration was found in rate of torque development. Maximum eccentric torque and EMG increased significantly for the paretic leg only. Mechanical work enhanced significantly in the paretic side only.The results of our study indicate that the selection of the effective vibration frequency depends upon the physical condition of neuromuscular system. Low vibration frequency intervention can increase the strength in weak muscles due to neuromuscular impairment and restricted physical activity.

  13. Model Indepedent Vibration Control

    OpenAIRE

    Yuan, Jing

    2010-01-01

    A NMIFC system is proposed for broadband vibration control. It has two important features. Feature F1 is that the NMIFC is stable without introducing any invasive effects, such as probing signals or controller perturbations, into the vibration system; feature F2 is

  14. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 4th edition of this textbook on linear stochastic vibration...

  15. Vibration Theory, Vol. 3

    DEFF Research Database (Denmark)

    Nielsen, Søren R. K.

    The present textbook has been written based on previous lecture notes for a course on stochastic vibration theory that is being given on the 9th semester at Aalborg University for M. Sc. students in structural engineering. The present 2nd edition of this textbook on linear stochastic vibration...

  16. Hydroelastic Vibrations of Ships

    DEFF Research Database (Denmark)

    Jensen, Jørgen Juncher; Folsø, Rasmus

    2002-01-01

    A formula for the necessary hull girder bending stiffness required to avoid serious springing vibrations is derived. The expression takes into account the zero crossing period of the waves, the ship speed and main dimensions. For whipping vibrations the probability of exceedance for the combined...

  17. Mechanical vibration and shock analysis, sinusoidal vibration

    CERN Document Server

    Lalanne, Christian

    2014-01-01

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

  18. Adaptations of mouse skeletal muscle to low intensity vibration training

    Science.gov (United States)

    McKeehen, James N.; Novotny, Susan A.; Baltgalvis, Kristen A.; Call, Jarrod A.; Nuckley, David J.; Lowe, Dawn A.

    2013-01-01

    Purpose We tested the hypothesis that low intensity vibration training in mice improves contractile function of hindlimb skeletal muscles and promotes exercise-related cellular adaptations. Methods We subjected C57BL/6J mice to 6 wk, 5 d·wk−1, 15 min·d−1 of sham or low intensity vibration (45 Hz, 1.0 g) while housed in traditional cages (Sham-Active, n=8; Vibrated-Active, n=10) or in small cages to restrict physical activity (Sham-Restricted, n=8; Vibrated-Restricted, n=8). Contractile function and resistance to fatigue were tested in vivo (anterior and posterior crural muscles) and ex vivo on the soleus muscle. Tibialis anterior and soleus muscles were evaluated histologically for alterations in oxidative metabolism, capillarity, and fiber types. Epididymal fat pad and hindlimb muscle masses were measured. Two-way ANOVAs were used to determine effects of vibration and physical inactivity. Results Vibration training resulted in a 10% increase in maximal isometric torque (P=0.038) and 16% faster maximal rate of relaxation (P=0.030) of the anterior crural muscles. Posterior crural muscles were unaffected by vibration, with the exception of greater rates of contraction in Vibrated-Restricted mice compared to Vibrated-Active and Sham-Restricted mice (P=0.022). Soleus muscle maximal isometric tetanic force tended to be greater (P=0.057) and maximal relaxation was 20% faster (P=0.005) in Vibrated compared to Sham mice. Restriction of physical activity induced muscle weakness but was not required for vibration to be effective in improving strength or relaxation. Vibration training did not impact muscle fatigability or any indicator of cellular adaptation investigated (P≥0.431). Fat pad but not hindlimb muscle masses were affected by vibration training. Conclusion Vibration training in mice improved muscle contractility, specifically strength and relaxation rates, with no indication of adverse effects to muscle function or cellular adaptations. PMID:23274599

  19. Vibrations of rotating machinery

    CERN Document Server

    Matsushita, Osami; Kanki, Hiroshi; Kobayashi, Masao; Keogh, Patrick

    2017-01-01

    This book opens with an explanation of the vibrations of a single degree-of-freedom (dof) system for all beginners. Subsequently, vibration analysis of multi-dof systems is explained by modal analysis. Mode synthesis modeling is then introduced for system reduction, which aids understanding in a simplified manner of how complicated rotors behave. Rotor balancing techniques are offered for rigid and flexible rotors through several examples. Consideration of gyroscopic influences on the rotordynamics is then provided and vibration evaluation of a rotor-bearing system is emphasized in terms of forward and backward whirl rotor motions through eigenvalue (natural frequency and damping ratio) analysis. In addition to these rotordynamics concerning rotating shaft vibration measured in a stationary reference frame, blade vibrations are analyzed with Coriolis forces expressed in a rotating reference frame. Other phenomena that may be assessed in stationary and rotating reference frames include stability characteristic...

  20. MissMech: An R Package for Testing Homoscedasticity, Multivariate Normality, and Missing Completely at Random (MCAR

    Directory of Open Access Journals (Sweden)

    Mortaza Jamshidian

    2014-01-01

    Full Text Available Researchers are often faced with analyzing data sets that are not complete. To prop- erly analyze such data sets requires the knowledge of the missing data mechanism. If data are missing completely at random (MCAR, then many missing data analysis techniques lead to valid inference. Thus, tests of MCAR are desirable. The package MissMech implements two tests developed by Jamshidian and Jalal (2010 for this purpose. These tests can be run using a function called TestMCARNormality. One of the tests is valid if data are normally distributed, and another test does not require any distributional assumptions for the data. In addition to testing MCAR, in some special cases, the function TestMCARNormality is also able to test whether data have a multivariate normal distribution. As a bonus, the functions in MissMech can also be used for the following additional tasks: (i test of homoscedasticity for several groups when data are completely observed, (ii perform the k-sample test of Anderson-Darling to determine whether k groups of univariate data come from the same distribution, (iii impute incomplete data sets using two methods, one where normality is assumed and one where no specific distributional assumptions are made, (iv obtain normal-theory maximum likelihood estimates for mean and covariance matrix when data are incomplete, along with their standard errors, and finally (v perform the Neymans test of uniformity. All of these features are explained in the paper, including examples.

  1. Effects of vibration training on force production in female basketball players.

    Science.gov (United States)

    Fernandez-Rio, Javier; Terrados, Nicolas; Fernandez-Garcia, Benjamin; Suman, Oscar E

    2010-05-01

    The goal of this research project was to investigate the long-term effects of whole-body vibration (WBV) training on force production. Thirty-one female basketball players were randomly distributed in an experimental group: VG (vibration) and a control group: CG (no vibration). Both groups participated in the same training program; however, the experimental group (VG) performed a set of exercises on a vibration platform (Power Plate) at 30- to 35-Hz frequency and 4 mm amplitude, whereas the CG performed the same exercises at 0 Hz. Muscle performance of the legs was tested on a contact-time platform (Ergojump, Finland) through several tests: squat jump (SJ), countermovement jump (CMJ), and 15-second maximal performance jump; squat leg power (knee extension) was also evaluated using an Ergopower machine (Bosco, Italy). After 14 weeks, there was a significant increase (p power. However, there were no significant differences between the VG and the CG for any of the parameters evaluated. The findings of this study indicate that WBV training has no additive or discernible effect on the strength development of female basketball players after several weeks of use, suggesting that the application of this technology has no advantages over traditional strength training methods.

  2. Development of S-wave portable vibrator; S ha potable vibrator shingen no kaihatsu

    Energy Technology Data Exchange (ETDEWEB)

    Kaida, Y.; Matsubara, Y. [OYO Corp., Tokyo (Japan); Nijhof, V.; Brouwer, J.

    1996-05-01

    An S-wave portable vibrator to serve as a seismic source has been developed for the purpose of applying the shallow-layer reflection method to the study of the soil ground. The author, et al., who previously developed a P-wave portable vibrator has now developed an S-wave version, considering the advantage of the S-wave over the P-wave in that, for example, the S-wave velocity may be directly compared with the N-value representing ground strength and that the S-wave travels more slowly than the P-wave through sticky soil promising a higher-resolution exploration. The experimentally constructed S-wave vibrator consists of a conventional P-wave vibrator and an L-type wooden base plate combined therewith. Serving as the monitor for vibration is a conventional accelerometer without any modification. The applicability test was carried out at a location where a plank hammering test was once conducted for reflection aided exploration, and the result was compared with that of the plank hammering test. As the result, it was found that after some preliminary treatment the results of the two tests were roughly the same but that both reflected waves were a little sharper in the S-wave vibrator test than in the plank hammering test. 4 refs., 9 figs., 1 tab.

  3. The impact of daily evaluation and spontaneous breathing test on the duration of pediatric mechanical ventilation: a randomized controlled trial.

    Science.gov (United States)

    Foronda, Flávia K; Troster, Eduardo J; Farias, Julio A; Barbas, Carmen S; Ferraro, Alexandre A; Faria, Lucília S; Bousso, Albert; Panico, Flávia F; Delgado, Artur F

    2011-11-01

    To assess whether the combination of daily evaluation and use of a spontaneous breathing test could shorten the duration of mechanical ventilation as compared with weaning based on our standard of care. Secondary outcome measures included extubation failure rate and the need for noninvasive ventilation. A prospective, randomized controlled trial. Two pediatric intensive care units at university hospitals in Brazil. The trial involved children between 28 days and 15 yrs of age who were receiving mechanical ventilation for at least 24 hrs. Patients were randomly assigned to one of two weaning protocols. In the test group, the children underwent a daily evaluation to check readiness for weaning with a spontaneous breathing test with 10 cm H2O pressure support and a positive end-expiratory pressure of 5 cm H2O for 2 hrs. The spontaneous breathing test was repeated the next day for children who failed it. In the control group, weaning was performed according to standard care procedures. A total of 294 eligible children were randomized, with 155 to the test group and 139 to the control group. The time to extubation was shorter in the test group, where the median mechanical ventilation duration was 3.5 days (95% confidence interval, 3.0 to 4.0) as compared to 4.7 days (95% confidence interval, 4.1 to 5.3) in the control group (p = .0127). This significant reduction in the mechanical ventilation duration for the intervention group was not associated with increased rates of extubation failure or noninvasive ventilation. It represents a 30% reduction in the risk of remaining on mechanical ventilation (hazard ratio: 0.70). A daily evaluation to check readiness for weaning combined with a spontaneous breathing test reduced the mechanical ventilation duration for children on mechanical ventilation for >24 hrs, without increasing the extubation failure rate or the need for noninvasive ventilation.

  4. 14th International Conference on Acoustics and Vibration of Mechanical Structures

    CERN Document Server

    Marinca, Vasile

    2018-01-01

    This book is a collection of papers presented at Acoustics and Vibration of Mechanical Structures 2017 – AVMS 2017 – highlighting the current trends and state-of-the-art developments in the field. It covers a broad range of topics, such as noise and vibration control, noise and vibration generation and propagation, the effects of noise and vibration, condition monitoring and vibration testing, modeling, prediction and simulation of noise and vibration, environmental and occupational noise and vibration, noise and vibration attenuators, as well as biomechanics and bioacoustics. The book also presents analytical, numerical and experimental techniques for evaluating linear and non-linear noise and vibration problems (including strong nonlinearity). It is primarily intended for academics, researchers and professionals, as well as PhD students in various fields of the acoustics and vibration of mechanical structures.

  5. Voluntary, Randomized, Student Drug-Testing: Impact in a Rural, Low-Income, Community

    Science.gov (United States)

    Barrington, Kyle D.

    2008-01-01

    Illegal drug use and abuse by the nation's secondary school students is a continuing public health issue and this is especially true for students living in rural, low-income areas where access to intervention and treatment services is often limited. To address this issue, some school districts have implemented voluntary, randomized, student …

  6. Anti-vibration characteristics of rubberised reinforced concrete beams

    OpenAIRE

    Rahman, M; Al-Ghalib, A; Mohammad, FA

    2014-01-01

    The flexural and vibration properties were examined in order to evaluate the anti-vibration characteristics of rubber modified reinforced concrete beam. The rubberised mixtures were produced by replacing 5, 7.5, and 10 % by mass of the fine aggregate with 1–4 mm scrap truck tyre crumb rubber particles. A series of reinforced concrete beam (1,200 × 135 × 90 mm3) was tested in a free vibration mode and then subsequently in a four point flexural tests. The input and output signals from vibration...

  7. A permutation test to analyse systematic bias and random measurement errors of medical devices via boosting location and scale models.

    Science.gov (United States)

    Mayr, Andreas; Schmid, Matthias; Pfahlberg, Annette; Uter, Wolfgang; Gefeller, Olaf

    2017-06-01

    Measurement errors of medico-technical devices can be separated into systematic bias and random error. We propose a new method to address both simultaneously via generalized additive models for location, scale and shape (GAMLSS) in combination with permutation tests. More precisely, we extend a recently proposed boosting algorithm for GAMLSS to provide a test procedure to analyse potential device effects on the measurements. We carried out a large-scale simulation study to provide empirical evidence that our method is able to identify possible sources of systematic bias as well as random error under different conditions. Finally, we apply our approach to compare measurements of skin pigmentation from two different devices in an epidemiological study.

  8. Random test of R22 and HFC leakage in cooling installations; Steekproefonderzoek R22 en HFK lekkage koelinstallaties

    Energy Technology Data Exchange (ETDEWEB)

    Pennartz, F.; Van den Bovenkamp, M. [KWA Bedrijfsadviseurs, Amersfoort (Netherlands)

    2013-02-15

    KWA Business Consultants has conducted a random test survey in the dairy industry, meat industry and a peer group in other food sectors. The main goal was to obtain data on the size and trends of R22 and HFC emissions in the period 2007-2010. The survey is carried out by collecting the data of refilling refrigeration installations that have been registered by the refrigeration contractors. In total 1984 installations of 193 companies participated in the random test [Dutch] Begin 2012 is in opdracht van Agentschap NL onderzoek uitgevoerd naar lekkages van R22 en HFK koudemiddelen uit koelinstallaties in de sectoren zuivel, vlees en overige gerelateerde sectoren in de voedingsmiddelenindustrie. Het onderzoek had de vorm van een steekproef. Er hebben 193 bedrijven deelgenomen; 1984 koelinstallaties zijn onderzocht. Het gemiddelde lekpercentages is 7. De lekkages zijn afkomstig van 10 procent van de installaties uit de onderzoeksgroep.

  9. Population testing for cancer predisposing BRCA1/BRCA2 mutations in the Ashkenazi-Jewish community: a randomized controlled trial.

    Science.gov (United States)

    Manchanda, Ranjit; Loggenberg, Kelly; Sanderson, Saskia; Burnell, Matthew; Wardle, Jane; Gessler, Sue; Side, Lucy; Balogun, Nyala; Desai, Rakshit; Kumar, Ajith; Dorkins, Huw; Wallis, Yvonne; Chapman, Cyril; Taylor, Rohan; Jacobs, Chris; Tomlinson, Ian; McGuire, Alistair; Beller, Uziel; Menon, Usha; Jacobs, Ian

    2015-01-01

    Technological advances raise the possibility of systematic population-based genetic testing for cancer-predisposing mutations, but it is uncertain whether benefits outweigh disadvantages. We directly compared the psychological/quality-of-life consequences of such an approach to family history (FH)-based testing. In a randomized controlled trial of BRCA1/2 gene-mutation testing in the Ashkenazi Jewish (AJ) population, we compared testing all participants in the population screening (PS) arm with testing those fulfilling standard FH-based clinical criteria (FH arm). Following a targeted community campaign, AJ participants older than 18 years were recruited by self-referral after pretest genetic counseling. The effects of BRCA1/2 genetic testing on acceptability, psychological impact, and quality-of-life measures were assessed by random effects regression analysis. All statistical tests were two-sided. One thousand, one hundred sixty-eight AJ individuals were counseled, 1042 consented, 1034 were randomly assigned (691 women, 343 men), and 1017 were eligible for analysis. Mean age was 54.3 (SD = 14.66) years. Thirteen BRCA1/2 carriers were identified in the PS arm, nine in the FH arm. Five more carriers were detected among FH-negative FH-arm participants following study completion. There were no statistically significant differences between the FH and PS arms at seven days or three months on measures of anxiety, depression, health anxiety, distress, uncertainty, and quality-of-life. Contrast tests indicated that overall anxiety (P = .0001) and uncertainty (P = .005) associated with genetic testing decreased; positive experience scores increased (P = .0001); quality-of-life and health anxiety did not change with time. Overall, 56% of carriers did not fulfill clinical criteria for genetic testing, and the BRCA1/2 prevalence was 2.45%. Compared with FH-based testing, population-based genetic testing in Ashkenazi Jews doesn't adversely affect short-term psychological

  10. A note on Using regression models to analyze randomized trials: asymptotically valid hypothesis tests despite incorrectly specified models.

    Science.gov (United States)

    Kim, Jane Paik

    2013-03-01

    In the context of randomized trials, Rosenblum and van der Laan (2009, Biometrics 63, 937-945) considered the null hypothesis of no treatment effect on the mean outcome within strata of baseline variables. They showed that hypothesis tests based on linear regression models and generalized linear regression models are guaranteed to have asymptotically correct Type I error regardless of the actual data generating distribution, assuming the treatment assignment is independent of covariates. We consider another important outcome in randomized trials, the time from randomization until failure, and the null hypothesis of no treatment effect on the survivor function conditional on a set of baseline variables. By a direct application of arguments in Rosenblum and van der Laan (2009), we show that hypothesis tests based on multiplicative hazards models with an exponential link, i.e., proportional hazards models, and multiplicative hazards models with linear link functions where the baseline hazard is parameterized, are asymptotically valid under model misspecification provided that the censoring distribution is independent of the treatment assignment given the covariates. In the case of the Cox model and linear link model with unspecified baseline hazard function, the arguments in Rosenblum and van der Laan (2009) cannot be applied to show the robustness of a misspecified model. Instead, we adopt an approach used in previous literature (Struthers and Kalbfleisch, 1986, Biometrika 73, 363-369) to show that hypothesis tests based on these models, including models with interaction terms, have correct type I error. Copyright © 2013, The International Biometric Society.

  11. Structural Stability and Vibration

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Pedersen, Pauli

    This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author at the Uni......This book offers an integrated introduction to the topic of stability and vibration. Strikingly, it describes stability as a function of boundary conditions and eigenfrequency as a function of both boundary conditions and column force. Based on a post graduate course held by the author...... and their derivation, thus stimulating them to write interactive and dynamic programs to analyze instability and vibrational modes....

  12. Effects of cognitive behavioral therapy with relaxation vs. imagery rescripting on test anxiety: A randomized controlled trial.

    Science.gov (United States)

    Reiss, Neele; Warnecke, Irene; Tolgou, Theano; Krampen, Dorothea; Luka-Krausgrill, Ursula; Rohrmann, Sonja

    2017-01-15

    Test anxiety is a common condition in students, which may lead to impaired academic performance as well as to distress. The primary objective of this study was to evaluate the effectiveness of two cognitive-behavioral interventions designed to reduce test anxiety. Test anxiety in the participants was diagnosed as social or specific phobia according to DSM-IV. Subsequently subjects were randomized to three groups: a moderated self-help group, which served as a control group, and two treatment groups, where either relaxation techniques or imagery rescripting were applied. Students suffering from test anxiety were recruited at two German universities (n=180). The randomized controlled design comprised three groups which received test anxiety treatment in weekly three-hour sessions over a period of five weeks. Treatment outcome was assessed with a test anxiety questionnaire, which was administered before and after treatment, as well as in a six-month follow-up. A repeated-measures ANOVA for participants with complete data (n=59) revealed a significant reduction of test anxiety from baseline to six-month follow-up in all three treatment groups (p<.001). Participants were included if they had a clinical diagnosis of test anxiety. The sample may therefore represent only more severe forms of text anxiety . Moreover, the sample size in this study was small, the numbers of participants per group differed, and treatment results were based on self-report. Due to the length of the treatment, an implementation of the group treatments used in this study might not be feasible in all settings. Group treatments constitute an effective method of treating test anxiety, e.g. in university settings. Imagery rescripting may particularly contribute to treatment efficacy. Copyright © 2016 Elsevier B.V. All rights reserved.

  13. The cost-effectiveness of rapid HIV testing in substance abuse treatment: results of a randomized trial.

    Science.gov (United States)

    Schackman, Bruce R; Metsch, Lisa R; Colfax, Grant N; Leff, Jared A; Wong, Angela; Scott, Callie A; Feaster, Daniel J; Gooden, Lauren; Matheson, Tim; Haynes, Louise F; Paltiel, A David; Walensky, Rochelle P

    2013-02-01

    The President's National HIV/AIDS Strategy calls for coupling HIV screening and prevention services with substance abuse treatment programs. Fewer than half of US community-based substance abuse treatment programs make HIV testing available on-site or through referral. We measured the cost-effectiveness of three HIV testing strategies evaluated in a randomized trial conducted in 12 community-based substance abuse treatment programs in 2009: off-site testing referral, on-site rapid testing with information only, on-site rapid testing with risk-reduction counseling. Data from the trial included patient demographics, prior testing history, test acceptance and receipt of results, undiagnosed HIV prevalence (0.4%) and program costs. The Cost-Effectiveness of Preventing AIDS Complications (CEPAC) computer simulation model was used to project life expectancy, lifetime costs, and quality-adjusted life years (QALYs) for HIV-infected individuals. Incremental cost-effectiveness ratios (2009 US $/QALY) were calculated after adding costs of testing HIV-uninfected individuals; costs and QALYs were discounted at 3% annually. Referral for off-site testing is less efficient (dominated) compared to offering on-site testing with information only. The cost-effectiveness ratio for on-site testing with information is $60,300/QALY in the base case, or $76,300/QALY with 0.1% undiagnosed HIV prevalence. HIV risk-reduction counseling costs $36 per person more without additional benefit. A strategy of on-site rapid HIV testing offer with information only in substance abuse treatment programs increases life expectancy at a cost-effectiveness ratio substance abuse treatment leaders should seek funding to implement on-site rapid HIV testing in substance abuse treatment programs for those not recently tested. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  14. Effectiveness of Different Rest Intervals Following Whole-Body Vibration on Vertical Jump Performance between College Athletes and Recreationally Trained Females

    Directory of Open Access Journals (Sweden)

    Nicole C. Dabbs

    2015-09-01

    Full Text Available The purpose of this study was to evaluate the effect of different rest intervals following whole-body vibration on counter-movement vertical jump performance. Sixteen females, eight recreationally trained and eight varsity athletes volunteered to participate in four testing visits separated by 24 h. Visit one acted as a familiarization visit where subjects were introduced to the counter-movement vertical jump and whole-body vibration protocols. Visits 2–4 contained 2 randomized conditions. Whole-body vibration was administered in four bouts of 30 s with 30 s rest between bouts. During whole-body vibration subjects performed a quarter squat every 5 s, simulating a counter-movement vertical jump. Whole-body vibration was followed by three counter-movement vertical jumps with five different rest intervals between the vibration exposure and jumping. For a control condition, subjects performed squats with no whole-body vibration. There was a significant (p < 0.05 main effect for time for vertical jump height, peak power output, and relative ground reaction forces, where a majority of individuals max jump from all whole-body vibration conditions was greater than the control condition. There were significant (p < 0.05 group differences, showing that varsity athletes had a greater vertical jump height and peak power output compared to recreationally trained females. There were no significant (p > 0.05 group differences for relative ground reaction forces. Practitioners and/or strength and conditioning coaches may utilize whole-body vibration to enhance acute counter-movement vertical jump performance after identifying individuals optimal rest time in order to maximize the potentiating effects.

  15. Active vibration control using DEAP actuators

    Science.gov (United States)

    Sarban, Rahimullah; Jones, Richard W.

    2010-04-01

    Dielectric electro-active polymer (DEAP) is a new type of smart material, which has the potential to be used to provide effective actuation for a wide range of applications. The properties of DEAP material place it somewhere between those of piezoceramics and shape memory alloys. Of the range of DEAP-based actuators that have been developed those having a cylindrical configuration are among the most promising. This contribution introduces the use of a tubular type DEAP actuator for active vibration control purposes. Initially the DEAP-based tubular actuator to be used in this study, produced by Danfoss PolyPower A/S, is introduced along with the static and dynamic characteristics. Secondly an electromechanical model of the tubular actuator is briefly reviewed and its ability to model the actuator's hysteresis characteristics for a range of periodic input signals at different frequencies demonstrated. The model will be used to provide hysteresis compensation in future vibration isolation studies. Experimental active vibration control using the actuator is then examined, specifically active vibration isolation of a 250 g mass subject to shaker generated 'ground vibration'. An adaptive feedforward control strategy is used to achieve this. The ability of the tubular actuator to reject both tonal and broadband random vibratory disturbances is then demonstrated.

  16. Composite materials inspection. [ultrasonic vibration holographic NDT

    Science.gov (United States)

    Erf, R. K.

    1974-01-01

    Investigation of the application requirements, advantages, and limitations of nondestructive testing by a technique of ultrasonic-vibration holographic-interferometry readout used in a production control facility for the inspection of a single product such as composite compressor blades. It is shown that, for the detection and characterization of disbonds in composite material structures, this technique may represent the most inclusive test method.

  17. Internal Temperature Control For Vibration Testers

    Science.gov (United States)

    Dean, Richard J.

    1996-01-01

    Vibration test fixtures with internal thermal-transfer capabilities developed. Made of aluminum for rapid thermal transfer. Small size gives rapid response to changing temperatures, with better thermal control. Setup quicker and internal ducting facilitates access to parts being tested. In addition, internal flows smaller, so less energy consumed in maintaining desired temperature settings.

  18. Vibrations and Stability

    DEFF Research Database (Denmark)

    Thomsen, Jon Juel

    About this textbook An ideal text for students that ties together classical and modern topics of advanced vibration analysis in an interesting and lucid manner. It provides students with a background in elementary vibrations with the tools necessary for understanding and analyzing more complex...... dynamical phenomena that can be encountered in engineering and scientific practice. It progresses steadily from linear vibration theory over various levels of nonlinearity to bifurcation analysis, global dynamics and chaotic vibrations. It trains the student to analyze simple models, recognize nonlinear...... phenomena and work with advanced tools such as perturbation analysis and bifurcation analysis. Explaining theory in terms of relevant examples from real systems, this book is user-friendly and meets the increasing interest in non-linear dynamics in mechanical/structural engineering and applied mathematics...

  19. Behavior of Cell on Vibrating Micro Ridges

    Directory of Open Access Journals (Sweden)

    Haruka Hino

    2015-06-01

    Full Text Available The effect of micro ridges on cells cultured at a vibrating scaffold has been studied in vitro. Several parallel lines of micro ridges have been made on a disk of transparent polydimethylsiloxane for a scaffold. To apply the vibration on the cultured cells, a piezoelectric element was attached on the outside surface of the bottom of the scaffold. The piezoelectric element was vibrated by the sinusoidal alternating voltage (Vp-p < 16 V at 1.0 MHz generated by a function generator. Four kinds of cells were used in the test: L929 (fibroblast connective tissue of C3H mouse, Hepa1-6 (mouse hepatoma, C2C12 (mouse myoblast, 3T3-L1 (mouse fat precursor cells. The cells were seeded on the micro pattern at the density of 2000 cells/cm2 in the medium containing 10% FBS (fetal bovine serum and 1% penicillin/ streptomycin. After the adhesion of cells in several hours, the cells are exposed to the ultrasonic vibration for several hours. The cells were observed with a phase contrast microscope. The experimental results show that the cells adhere, deform and migrate on the scaffold with micro patterns regardless of the ultrasonic vibration. The effects of the vibration and the micro pattern depend on the kind of cells.

  20. Physiology responses of Rhesus monkeys to vibration

    Science.gov (United States)

    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