Science.gov

Sample records for launch acoustic excitation

  1. Vibroacoustic Response of the NASA ACTS Spacecraft Antenna to Launch Acoustic Excitation

    NASA Technical Reports Server (NTRS)

    Larko, Jeffrey M.; Cotoni, Vincent

    2008-01-01

    The Advanced Communications Technology Satellite was an experimental NASA satellite launched from the Space Shuttle Discovery. As part of the ground test program, the satellite s large, parabolic reflector antennas were exposed to a reverberant acoustic loading to simulate the launch acoustics in the Shuttle payload bay. This paper describes the modelling and analysis of the dynamic response of these large, composite spacecraft antenna structure subjected to a diffuse acoustic field excitation. Due to the broad frequency range of the excitation, different models were created to make predictions in the various frequency regimes of interest: a statistical energy analysis (SEA) model to capture the high frequency response and a hybrid finite element-statistical energy (hybrid FE-SEA) model for the low to mid-frequency responses. The strengths and limitations of each of the analytical techniques are discussed. The predictions are then compared to the measured acoustic test data and to a boundary element (BEM) model to evaluate the performance of the hybrid techniques.

  2. AST Launch Vehicle Acoustics

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, D.; Giacomoni, D.

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible pre-launch test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments and to determine the acoustic reduction with an above deck water sound suppression system. The SMAT was conducted at Marshall Space Flight Center and the test article included a 5% scale SLS vehicle model, tower and Mobile Launcher. Acoustic and pressure data were measured by approximately 250 instruments. The SMAT liftoff acoustic results are presented, findings are discussed and a comparison is shown to the Ares I Scale Model Acoustic Test (ASMAT) results.

  3. Stennis conducts launch acoustics testing

    NASA Image and Video Library

    2010-04-26

    Operators at the E-3 Test Stand at NASA's John C. Stennis Space Center completed 32 acoustics tests April 16-28, designed to gather critical information for future space launches. Stennis operators investigated lift-off acoustics that can damage space vehicle components by testing the benefits of injecting water onto the upper surface of the launch pad to suppress sound. The Stennis tests provided critical data to determine what can be gained from this approach.

  4. Acoustically excited heated jets. 1: Internal excitation

    NASA Technical Reports Server (NTRS)

    Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Salikuddin, M.; Morris, P. J.

    1988-01-01

    The effects of relatively strong upstream acoustic excitation on the mixing of heated jets with the surrounding air are investigated. To determine the extent of the available information on experiments and theories dealing with acoustically excited heated jets, an extensive literature survey was carried out. The experimental program consisted of flow visualization and flowfield velocity and temperature measurements for a broad range of jet operating and flow excitation conditions. A 50.8-mm-diam nozzle was used for this purpose. Parallel to the experimental study, an existing theoretical model of excited jets was refined to include the region downstream of the jet potential core. Excellent agreement was found between theory and experiment in moderately heated jets. However, the theory has not yet been confirmed for highly heated jets. It was found that the sensitivity of heated jets to upstream acoustic excitation varies strongly with the jet operating conditions and that the threshold excitation level increases with increasing jet temperature. Furthermore, the preferential Strouhal number is found not to change significantly with a change of the jet operating conditions. Finally, the effects of the nozzle exit boundary layer thickness appear to be similar for both heated and unheated jets at low Mach numbers.

  5. Acoustic and Vibration Environment for Crew Launch Vehicle Mobile Launcher

    NASA Technical Reports Server (NTRS)

    Vu, Bruce T.

    2007-01-01

    A launch-induced acoustic environment represents a dynamic load on the exposed facilities and ground support equipment (GSE) in the form of random pressures fluctuating around the ambient atmospheric pressure. In response to these fluctuating pressures, structural vibrations are generated and transmitted throughout the structure and to the equipment items supported by the structure. Certain equipment items are also excited by the direct acoustic input as well as by the vibration transmitted through the supporting structure. This paper presents the predicted acoustic and vibration environments induced by the launch of the Crew Launch Vehicle (CLV) from Launch Complex (LC) 39. The predicted acoustic environment depicted in this paper was calculated by scaling the statistically processed measured data available from Saturn V launches to the anticipated environment of the CLV launch. The scaling was accomplished by using the 5-segment Solid Rocket Booster (SRB) engine parameters. Derivation of vibration environment for various Mobile Launcher (ML) structures throughout the base and tower was accomplished by scaling the Saturn V vibration environment.

  6. Launch Excitement with Water Rockets

    ERIC Educational Resources Information Center

    Sanchez, Juan Carlos; Penick, John

    2007-01-01

    Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable…

  7. Launch Excitement with Water Rockets

    ERIC Educational Resources Information Center

    Sanchez, Juan Carlos; Penick, John

    2007-01-01

    Explosions and fires--these are what many students are waiting for in science classes. And when they do occur, students pay attention. While we can't entertain our students with continual mayhem, we can catch their attention and cater to their desires for excitement by saying, "Let's make rockets." In this activity, students make simple, reusable…

  8. Gaussian Acoustic Classifier for the Launch of Three Weapon Systems

    DTIC Science & Technology

    2013-09-01

    Gaussian Acoustic Classifier for the Launch of Three Weapon Systems by Christine Yang and Geoffrey H. Goldman ARL-TN-0576 September 2013...0576 September 2013 Gaussian Acoustic Classifier for the Launch of Three Weapon Systems Christine Yang and Geoffrey H. Goldman Sensors...Final 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Gaussian Acoustic Classifier for the Launch of Three Weapon Systems 5a. CONTRACT NUMBER 5b

  9. 24. LAUNCH CONTROL CAPSULE. ENTRANCE TO ACOUSTICAL ENCLOSURE. SHOCK ISOLATOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. LAUNCH CONTROL CAPSULE. ENTRANCE TO ACOUSTICAL ENCLOSURE. SHOCK ISOLATOR AT FAR LEFT. VIEW TO NORTH. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  10. 27. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE. COMMUNICATIONS CONSOLE AT LEFT; ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE. COMMUNICATIONS CONSOLE AT LEFT; LAUNCH CONTROL CONSOLE AT RIGHT. PADLOCKED PANEL AT TOP CENTER CONTAINS MISSILE LAUNCH KEYS. SHOCK ISOLATOR AT FAR LEFT. VIEW TO EAST. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  11. Boundary layer control by acoustic excitation

    NASA Technical Reports Server (NTRS)

    Papathanasiou, A. G.; Nagel, R. T.

    1986-01-01

    An experimental program in which the effectiveness of a single large eddy break-up device (LEBU) blade is enhanced by proper acoustic excitation is described. An acoustic pulse, phase-locked to the incident large eddies and directed at the LEBU can enhance the large eddy cancellation process and can in effect lead to a decrease in the skin friction coefficient. Cross-correlation data and turbulence intensity measurements show that this acoustic excitation causes eddy cancellation at the trailing edge of the manipulator plate. It is concluded that both reduced turbulent boundary layer mixing and significant drag reduction can be achieved upon proper acoustic input to a LEBU.

  12. 26. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW MEMBER LIEUTENANT KEVIN R. MCCLUNEY AT COMMUNICATIONS CONSOLE. LAUNCH CONTROL CONSOLE IN FOREGROUND. VIEW TO NORTH. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  13. 30. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE. OPERATORS' CHAIR AND COMMUNICATIONS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE. OPERATORS' CHAIR AND COMMUNICATIONS CONSOLE IN FOREGROUND. ELECTRONIC EQUIPMENT RACK AT LEFT; LAUNCH CONTROL CONSOLE WITH CAPTAIN JAMES L. KING, JR. IN CENTER. LIEUTENANT KEVIN R. MCCLUNEY IN BACKGROUND. VIEW TO SOUTHEAST. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  14. New excitation method for acoustic logging transmitters

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Ju, X. D.; Tan, B. H.; Lu, J. Q.; Men, B. Y.; Wu, W. H.; Chen, J. Y.

    2017-08-01

    The traditional transducer coupled excitation method for acoustic logging tools has many disadvantages given its transformer characteristics. A new excitation method that uses a complex programmable logic device and vertical metal oxide semiconductor field effect transistor is proposed in this study. Theoretical calculations, finite element analyses and acoustic experiments are performed to compare the acoustic and electrical characteristics of the new and the traditional methods. Results show that the acoustic waves emitted by the new method have lower dominant frequencies and approximately four times more acoustic energy than those emitted by the transformer coupled method. Furthermore, the adjustment functions and channel consistencies of the new electrical circuit are better than those of the traditional method. All the results indicate that the logging tools that use the new method are more flexible and accurate with better detection depth and sensitivity. This method has already been used in logging tools and has improved their performance.

  15. Viscous flow drag reduction by acoustic excitation

    NASA Technical Reports Server (NTRS)

    Nagel, Robert T.

    1986-01-01

    An experimental program in which the effectiveness of a single large eddy break up (LEBU) blade is enhanced by proper acoustic excitation is described. Acoustic waves are generated in response to the incident large scale eddies and directed at the blade trailing edge through the test surface floor below the manipulator blade. The acoustic input is phase locked to the incident flow. Control of the acoustic input apparently allows enhancement of the large eddy cancellation process leading to a decrease of skin friction coefficient. Control of this process with acoustic excitation indicates that vortex unwinding is the mechanism for large eddy destruction in the boundary layer. A deeper understanding of this phenomena could lead to better drag reduction technology and further understanding of the physics of the turbulent boundary layer.

  16. Aeroacoustic characteristics of acoustically excited jets

    NASA Astrophysics Data System (ADS)

    Vlasov, E. V.; Ginevskii, A. S.; Karavosov, R. K.

    The effect of acoustic excitation on the aerodynamic and acoustic characteristics of air jets at Reynolds numbers of (0.5-4) x 10 to the 5th was studied experimentally. It is shown that high-frequency excitation (Sh sub s not greater than 1) causes a reduction in the range of the jet and an increase in broadband noise generated by the jet. High-frequency excitation (Sh sub s = 3-5) produces the opposite effect. These effects were observed for both laminar and turbulent boundary layers on the nozzle wall in the exit section. An analysis is made of the parameters of the far acoustic field of the jet as it is excited by gas-jet radiators.

  17. Improving Fidelity of Launch Vehicle Liftoff Acoustic Simulations

    NASA Technical Reports Server (NTRS)

    Liever, Peter; West, Jeff

    2016-01-01

    Launch vehicles experience high acoustic loads during ignition and liftoff affected by the interaction of rocket plume generated acoustic waves with launch pad structures. Application of highly parallelized Computational Fluid Dynamics (CFD) analysis tools optimized for application on the NAS computer systems such as the Loci/CHEM program now enable simulation of time-accurate, turbulent, multi-species plume formation and interaction with launch pad geometry and capture the generation of acoustic noise at the source regions in the plume shear layers and impingement regions. These CFD solvers are robust in capturing the acoustic fluctuations, but they are too dissipative to accurately resolve the propagation of the acoustic waves throughout the launch environment domain along the vehicle. A hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) modeling framework has been developed to improve such liftoff acoustic environment predictions. The framework combines the existing highly-scalable NASA production CFD code, Loci/CHEM, with a high-order accurate discontinuous Galerkin (DG) solver, Loci/THRUST, developed in the same computational framework. Loci/THRUST employs a low dissipation, high-order, unstructured DG method to accurately propagate acoustic waves away from the source regions across large distances. The DG solver is currently capable of solving up to 4th order solutions for non-linear, conservative acoustic field propagation. Higher order boundary conditions are implemented to accurately model the reflection and refraction of acoustic waves on launch pad components. The DG solver accepts generalized unstructured meshes, enabling efficient application of common mesh generation tools for CHEM and THRUST simulations. The DG solution is coupled with the CFD solution at interface boundaries placed near the CFD acoustic source regions. Both simulations are executed simultaneously with coordinated boundary condition data exchange.

  18. 28. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW MEMBERS (FRONT TO BACK) LIEUTENANT KEVIN R. MCCLUNEY AND CAPTAIN JAMES L. KING, JR. SHOCK ISOLATOR AND ELECTRONIC EQUIPMENT RACK AT FAR LEFT. VIEW TO SOUTH. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  19. 25. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW MEMBERS (FRONT TO BACK) CAPTAIN JAMES L. KING, JR. AT LAUNCH CONTROL CONSOLE AND LIEUTENANT KEVIN R. MCCLUNEY AT COMMUNICATIONS CONSOLE. RADIO TRANSMITTER AND RECEIVER RACKS AT FAR RIGHT; ELECTRONIC EQUIPMENT RACKS AT FAR LEFT. VIEW TO NORTH. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  20. Modeling the near acoustic field of a rocket during launch

    NASA Technical Reports Server (NTRS)

    Mauritzen, David W.

    1989-01-01

    The design of launch pad structures is critically dependent upon the stresses imposed by the acoustical pressure field generated by the rocket engines during launch. The purpose of this effort is to better describe the acoustical field in the immediate launch area. Since the problem is not analytically tractable, empirical modeling will be employed so that useful results may be obtained for structural design purposes. The plume of the rocket is considered to be a volumetric acoustic source, and is broken down into incremental contributing volumes. A computer program has been written to sum all the contributions to find the total sound pressure level at an arbitrary point. A constant density source is initially assumed and the acoustic field evaluated for several cases to verify the correct operation of the program.

  1. 29. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. LAUNCH CONTROL CAPSULE. ACOUSTICAL ENCLOSURE WITH MISSILE COMBAT CREW MEMBERS (FRONT TO BACK) LIEUTENANT KEVIN R. MCCLUNEY AND CAPTAIN JAMES L. KING, JR. AT CONSOLES. REFRIGERATOR AT RIGHT FLANKED BY RADIO EQUIPMENT (RIGHT) AND FILE CABINETS (LEFT). VIEW TO SOUTHWEST. - Minuteman III ICBM Launch Control Facility November-1, 1.5 miles North of New Raymer & State Highway 14, New Raymer, Weld County, CO

  2. Dual excitation acoustic paramagnetic logging tool

    DOEpatents

    Vail, W.B. III.

    1989-02-14

    New methods and apparatus are disclosed which allow measurement of the presence of oil and water in geological formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleons present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth's magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation. The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be performed in open boreholes and in cased well bores. The Dual Excitation Acoustic Paramagnetic Logging Tool employing two acoustic sources is also described. 6 figs.

  3. Dual excitation acoustic paramagnetic logging tool

    DOEpatents

    Vail, III, William B.

    1989-01-01

    New methods and apparatus are disclosed which allow measurement of the presence of oil and water in gelogical formations using a new physical effect called the Acoustic Paramagnetic Logging Effect (APLE). The presence of petroleum in formation causes a slight increase in the earth's magnetic field in the vicinity of the reservoir. This is the phenomena of paramagnetism. Application of an acoustic source to a geological formation at the Larmor frequency of the nucleous present causes the paramagnetism of the formation to disappear. This results in a decrease in the earth's magnetic field in the vicinity of the oil bearing formation. Repetitively frequency sweeping the acoustic source through the Larmor frequency of the nucleons present (approx. 2 kHz) causes an amplitude modulation of the earth's magnetic field which is a consequence of the APLE. The amplitude modulation of the earth's magnetic field is measured with an induction coil gradiometer and provides a direct measure of the amount of oil and water in the excitation zone of the formation. The phase of the signal is used to infer the longitudinal relaxation times of the fluids present, which results in the ability in general to separate oil and water and to measure the viscosity of the oil present. Such measurements may be preformed in open boreholes and in cased well bores. The Dual Excitation Acoustic Paramagnetic Logging Tool employing two acoustic sources is also described.

  4. Equivalent Source Method Applied to Launch Acoustic Simulations

    NASA Technical Reports Server (NTRS)

    Housman, Jeffrey A.; Barad, Michael F.; Kiris, Cetin

    2012-01-01

    Aeroacoustic simulations of the launch environment are described. A hybrid computational fluid dynamics (CFD)/computational aeroacoustic (CAA) approach is developed in order to accurately and efficiently predict the sound pressure level spectrum on the launch vehicle and surrounding structures. The high-fidelity CFD code LAVA (Launch Ascent and Vehicle Analysis), is used to generate pressure time history at select locations in the flow field. A 3D exterior Helmholtz solver is then used to iteratively determine a set of monopole sources which mimic the noise generating mechanisms identified by the CFD solver. The acoustic pressure field generated from the Helmholtz solver is then used to evaluate the sound pressure levels.

  5. Prediction of Launch Vehicle Ignition Overpressure and Liftoff Acoustics

    NASA Technical Reports Server (NTRS)

    Casiano, Matthew

    2009-01-01

    The LAIOP (Launch Vehicle Ignition Overpressure and Liftoff Acoustic Environments) program predicts the external pressure environment generated during liftoff for a large variety of rocket types. These environments include ignition overpressure, produced by the rapid acceleration of exhaust gases during rocket-engine start transient, and launch acoustics, produced by turbulence in the rocket plume. The ignition overpressure predictions are time-based, and the launch acoustic predictions are frequency-based. Additionally, the software can predict ignition overpressure mitigation, using water-spray injection into the rocket exhaust stream, for a limited number of configurations. The framework developed for these predictions is extensive, though some options require additional relevant data and development time. Once these options are enabled, the already extensively capable code will be further enhanced. The rockets, or launch vehicles, can either be elliptically or cylindrically shaped, and up to eight strap-on structures (boosters or tanks) are allowed. Up to four engines are allowed for the core launch vehicle, which can be of two different types. Also, two different sizes of strap-on structures can be used, and two different types of booster engines are allowed. Both tabular and graphical presentations of the predicted environments at the selected locations can be reviewed by the user. The output includes summaries of rocket-engine operation, ignition overpressure time histories, and one-third octave sound pressure spectra of the predicted launch acoustics. Also, documentation is available to the user to help him or her understand the various aspects of the graphical user interface and the required input parameters.

  6. Development of an acoustic actuator for launch vehicle noise reduction.

    PubMed

    Henderson, Benjamin K; Lane, Steven A; Gussy, Joel; Griffin, Steve; Farinholt, Kevin M

    2002-01-01

    In many active noise control applications, it is necessary that acoustic actuators be mounted in small enclosures due to volume constraints and in order to remain unobtrusive. However, the air spring of the enclosure is detrimental to the low-frequency performance of the actuator. For launch vehicle noise control applications, mass and volume constraints are very limiting, but the low-frequency performance of the actuator is critical. This work presents a novel approach that uses a nonlinear buckling suspension system and partial evacuation of the air within the enclosure to yield a compact, sealed acoustic driver that exhibits a very low natural frequency. Linear models of the device are presented and numerical simulations are given to illustrate the advantages of this design concept. An experimental prototype was built and measurements indicate that this design can significantly improve the low-frequency response of compact acoustic actuators.

  7. Comparison of acoustic and mechanical excitation for modal response measurements

    NASA Astrophysics Data System (ADS)

    Musson, B. G.; Stevens, J. R.

    An acoustic field is examined as an alternate to mechanical excitation of a test specimen to measure modal response. A square, flat plate with clamped edges is used because classical analytical solutions to its modal analysis are readily available. A small hammer with a built-in force transducer is used to mechanically excite the plate, and the plate is excited with electro-pneumatic acoustic drivers coupled to a progressive-wave test fixture. Band limited random amplitude acoustic waves over a frequency range of 50 to 1000 Hz are applied at grazing incidence to the plate. The acoustic field is characterized and a microphone at a single fixed position is used to provide the reference forcing function. Results are compared with the analytical solutions and with the mechanically excited results. Conclusions are presented concerning the equivalence of acoustic and mechanical excitation for obtaining modal response.

  8. Acoustic-Modal Testing of the Ares I Launch Abort System Attitude Control Motor Valve

    NASA Technical Reports Server (NTRS)

    Davis, R. Benjamin; Fischbach, Sean R.

    2010-01-01

    The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.

  9. Acoustic-Modal Testing of the Ares I Launch Abort System Attitude Control Motor Valve

    NASA Technical Reports Server (NTRS)

    Davis, R. Benjamin; Fischbach, Sean R.

    2010-01-01

    The Attitude Control Motor (ACM) is being developed for use in the Launch Abort System (LAS) of NASA's Ares I launch vehicle. The ACM consists of a small solid rocket motor and eight actuated pintle valves that directionally allocate.thrust_- 1t.has-been- predicted-that significant unsteady. pressure.fluctuations.will.exist. inside the-valves during operation. The dominant frequencies of these oscillations correspond to the lowest several acoustic natural frequencies of the individual valves. An acoustic finite element model of the fluid volume inside the valve has been critical to the prediction of these frequencies and their associated mode shapes. This work describes an effort to experimentally validate the acoustic finite model of the valve with an acoustic modal test. The modal test involved instrumenting a flight-like valve with six microphones and then exciting the enclosed air with a loudspeaker. The loudspeaker was configured to deliver broadband noise at relatively high sound pressure levels. The aquired microphone signals were post-processed and compared to results generated from the acoustic finite element model. Initial comparisons between the test data and the model results revealed that additional model refinement was necessary. Specifically, the model was updated to implement a complex impedance boundary condition at the entrance to the valve supply tube. This boundary condition models the frequency-dependent impedance that an acoustic wave will encounter as it reaches the end of the supply tube. Upon invoking this boundary condition, significantly improved agreement between the test data and the model was realized.

  10. Magneto-acoustic imaging by continuous-wave excitation.

    PubMed

    Shunqi, Zhang; Zhou, Xiaoqing; Tao, Yin; Zhipeng, Liu

    2017-04-01

    The electrical characteristics of tissue yield valuable information for early diagnosis of pathological changes. Magneto-acoustic imaging is a functional approach for imaging of electrical conductivity. This study proposes a continuous-wave magneto-acoustic imaging method. A kHz-range continuous signal with an amplitude range of several volts is used to excite the magneto-acoustic signal and improve the signal-to-noise ratio. The magneto-acoustic signal amplitude and phase are measured to locate the acoustic source via lock-in technology. An optimisation algorithm incorporating nonlinear equations is used to reconstruct the magneto-acoustic source distribution based on the measured amplitude and phase at various frequencies. Validation simulations and experiments were performed in pork samples. The experimental and simulation results agreed well. While the excitation current was reduced to 10 mA, the acoustic signal magnitude increased up to 10(-7) Pa. Experimental reconstruction of the pork tissue showed that the image resolution reached mm levels when the excitation signal was in the kHz range. The signal-to-noise ratio of the detected magneto-acoustic signal was improved by more than 25 dB at 5 kHz when compared to classical 1 MHz pulse excitation. The results reported here will aid further research into magneto-acoustic generation mechanisms and internal tissue conductivity imaging.

  11. Investigating Response from Attached and Separated Flow Excitations on a Real Launch Vehicle using SEA

    NASA Technical Reports Server (NTRS)

    Harrison, Phil; LaVerde, Bruce; Teague,David

    2009-01-01

    Statistical Energy Analysis (SEA) response has been fairly well anchored to test observations for Diffuse Acoustic Field (DAF) loading by others. Meanwhile, not many examples can be found in the literature anchoring the SEA vehicle panel response results to Turbulent Boundary Layer (TBL) fluctuating pressure excitations. This deficiency is especially true for supersonic trajectories such as those required by this nation s launch vehicles. Response and excitation data from vehicle flight measurements gathered during the development flight era of the Space Shuttle have been used in a trial to assess the sensitivity of response analysis to certain known and unknown parameters of the flight. This assessment compares vibration response predictions for TBL excitations produced by the SEA tool to flight measurements. A secondary, but perhaps more important objective, is to provide more clarity concerning the accuracy and conservatism that can be expected from response estimates to TBL-excited vehicle models in SEA. What range of parameters must be included in such an analysis in order to land on the conservative side in response predictions? What is the variability produced in the results with changes in these parameters? The TBL fluid structure loading model used for this study is provided from the SEA module of the commercial code VA One.

  12. Investigating Response from Attached and Separated Flow Excitations on a Real Launch Vehicle using SEA

    NASA Technical Reports Server (NTRS)

    Harrison, Phil; LaVerde, Bruce; Teague,David

    2009-01-01

    Statistical Energy Analysis (SEA) response has been fairly well anchored to test observations for Diffuse Acoustic Field (DAF) loading by others. Meanwhile, not many examples can be found in the literature anchoring the SEA vehicle panel response results to Turbulent Boundary Layer (TBL) fluctuating pressure excitations. This deficiency is especially true for supersonic trajectories such as those required by this nation s launch vehicles. Response and excitation data from vehicle flight measurements gathered during the development flight era of the Space Shuttle have been used in a trial to assess the sensitivity of response analysis to certain known and unknown parameters of the flight. This assessment compares vibration response predictions for TBL excitations produced by the SEA tool to flight measurements. A secondary, but perhaps more important objective, is to provide more clarity concerning the accuracy and conservatism that can be expected from response estimates to TBL-excited vehicle models in SEA. What range of parameters must be included in such an analysis in order to land on the conservative side in response predictions? What is the variability produced in the results with changes in these parameters? The TBL fluid structure loading model used for this study is provided from the SEA module of the commercial code VA One.

  13. VEGA Launch Vehicle Vibro-Acoustic Approach for Multi Payload Configuration Qualification

    NASA Astrophysics Data System (ADS)

    Bartoccini, D.; Di Trapani, C.; Fotino, D.; Bonnet, M.

    2014-06-01

    Acoustic loads are one of the principal source of structural vibration and internal noise during a launch vehicle flight but do not generally present a critical design condition for the main load-carrying structure. However, acoustic loads may be critical to the proper functioning of vehicle components and their supporting structures, which are otherwise lightly loaded. Concerning the VEGA program, in order to demonstrate VEGA Launch Vehicle (LV) on-ground qualification, prior to flight, to the acoustic load, the following tests have been performed: small-scale acoustic test intended for the determination of the acoustic loading of the LV and its nature and full-scale acoustic chamber test to determine the vibro-acoustic response of the structures as well as of the acoustic cavities.

  14. Laboratory observations of self-excited dust acoustic shock waves

    NASA Astrophysics Data System (ADS)

    Merlino, Robert L.; Heinrich, Jonathon R.; Kim, Su-Hyun

    2009-11-01

    Dust acoustic waves have been discussed in connection with dust density structures in Saturn's rings and the Earth's mesosphere, and as a possible mechanism for triggering condensation of small grains in dust molecular clouds. Dust acoustic waves are a ubiquitous occurrence in laboratory dusty plasmas formed in glow discharges. We report observations of repeated, self-excited dust acoustic shock waves in a dc glow discharge dusty plasma using high-speed video imaging. Two major observations will be presented: (1) The self-steepening of a nonlinear dust acoustic wave into a saw-tooth wave with sharp gradient in dust density, very similar to those found in numerical solutions [1] of the fully nonlinear fluid equations for nondispersive dust acoustic waves, and (2) the collision and confluence of two dust acoustic shock waves. [4pt] [1] B. Eliasson and P. K. Shukla, Phys. Rev. E 69, 067401 (2004).

  15. Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

    NASA Technical Reports Server (NTRS)

    Nance, Donald K.; Liever, Peter A.

    2015-01-01

    The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test (SMAT), conducted at Marshall Space Flight Center (MSFC). The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

  16. Space Launch System Scale Model Acoustic Test Ignition Overpressure Testing

    NASA Technical Reports Server (NTRS)

    Nance, Donald; Liever, Peter; Nielsen, Tanner

    2015-01-01

    The overpressure phenomenon is a transient fluid dynamic event occurring during rocket propulsion system ignition. This phenomenon results from fluid compression of the accelerating plume gas, subsequent rarefaction, and subsequent propagation from the exhaust trench and duct holes. The high-amplitude unsteady fluid-dynamic perturbations can adversely affect the vehicle and surrounding structure. Commonly known as ignition overpressure (IOP), this is an important design-to environment for the Space Launch System (SLS) that NASA is currently developing. Subscale testing is useful in validating and verifying the IOP environment. This was one of the objectives of the Scale Model Acoustic Test, conducted at Marshall Space Flight Center. The test data quantifies the effectiveness of the SLS IOP suppression system and improves the analytical models used to predict the SLS IOP environments. The reduction and analysis of the data gathered during the SMAT IOP test series requires identification and characterization of multiple dynamic events and scaling of the event waveforms to provide the most accurate comparisons to determine the effectiveness of the IOP suppression systems. The identification and characterization of the overpressure events, the waveform scaling, the computation of the IOP suppression system knockdown factors, and preliminary comparisons to the analytical models are discussed.

  17. Enhanced viscous flow drag reduction using acoustic excitation

    NASA Technical Reports Server (NTRS)

    Nagel, R. T.

    1988-01-01

    Large eddy break up devices (LEBUs) constitute a promising method of obtaining drag reduction in a turbulent boundary layer. Enhancement of the LEBU effectiveness by exciting its trailing edge with acoustic waves phase locked to the large scale structure influencing the momentum transfer to the wall is sought. An initial estimate of the required sound pressure level for an effective pulse was obtained by considering the magnitude of the pressure perturbations at the near wake of a thin plate in inviscid flow. Detailed skin friction measurments were obtained in the flow region downstream of a LEBU excited with acoustic waves. The data are compared with skin friction measurements of a simply manipulated flow, without acoustic excitation and with a plain flow configuration. The properties and the scales of motion in the flow regime downstream of the acoustically excited LEBU are studied. A parametric study based upon the characteristics of the acoustic input was pursued in addition to the careful mapping of the drag reduction phenomenon within the acoustically manipulated boundary layer. This study of boundary layer manipulation has lead to improved skin friction drag reduction and further understanding of the turbulent boundary layer.

  18. Investigating Response from Turbulent Boundary Layer Excitations on a Real Launch Vehicle using SEA

    NASA Technical Reports Server (NTRS)

    Harrison, Phillip; LaVerde,Bruce; Teague, David

    2009-01-01

    Statistical Energy Analysis (SEA) response has been fairly well anchored to test observations for Diffuse Acoustic Field (DAF) loading by others. Meanwhile, not many examples can be found in the literature anchoring the SEA vehicle panel response results to Turbulent Boundary Layer (TBL) fluctuating pressure excitations. This deficiency is especially true for supersonic trajectories such as those required by this nation s launch vehicles. Space Shuttle response and excitation data recorded from vehicle flight measurements during the development flights were used in a trial to assess the capability of the SEA tool to predict similar responses. Various known/measured inputs were used. These were supplemented with a range of assumed values in order to cover unknown parameters of the flight. This comparison is presented as "Part A" of the study. A secondary, but perhaps more important, objective is to provide more clarity concerning the accuracy and conservatism that can be expected from response estimates of TBL-excited vehicle models in SEA (Part B). What range of parameters must be included in such an analysis in order to land on the conservative side in response predictions? What is the sensitivity of changes in these input parameters on the results? The TBL fluid structure loading model used for this study is provided by the SEA module of the commercial code VA One.

  19. Observation of self-excited acoustic vortices in defect-mediated dust acoustic wave turbulence.

    PubMed

    Tsai, Ya-Yi; I, Lin

    2014-07-01

    Using the self-excited dust acoustic wave as a platform, we demonstrate experimental observation of self-excited fluctuating acoustic vortex pairs with ± 1 topological charges through spontaneous waveform undulation in defect-mediated turbulence for three-dimensional traveling nonlinear longitudinal waves. The acoustic vortex pair has helical waveforms with opposite chirality around the low-density hole filament pair in xyt space (the xy plane is the plane normal to the wave propagation direction). It is generated through ruptures of sequential crest surfaces and reconnections with their trailing ruptured crest surfaces. The initial rupture is originated from the amplitude reduction induced by the formation of the kinked wave crest strip with strong stretching through the undulation instability. Increasing rupture causes the separation of the acoustic vortex pair after generation. A similar reverse process is followed for the acoustic vortex annihilating with the opposite-charged acoustic vortex from the same or another pair generation.

  20. Assessment of Microphone Phased Array for Measuring Launch Vehicle Lift-off Acoustics

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto

    2012-01-01

    The specific purpose of the present work was to demonstrate the suitability of a microphone phased array for launch acoustics applications via participation in selected firings of the Ares I Scale Model Acoustics Test. The Ares I Scale Model Acoustics Test is a part of the discontinued Constellation Program Ares I Project, but the basic understanding gained from this test is expected to help development of the Space Launch System vehicles. Correct identification of sources not only improves the predictive ability, but provides guidance for a quieter design of the launch pad and optimization of the water suppression system. This document contains the results of the NASA Engineering and Safety Center assessment.

  1. Experimental study of planar opposed jets with acoustic excitation

    NASA Astrophysics Data System (ADS)

    Li, Wei-Feng; Huang, Guo-Feng; Tu, Gong-Yi; Liu, Hai-Feng; Wang, Fu-Chen

    2013-01-01

    Oscillation behaviors of planar opposed jets with acoustic excitation were experimentally investigated. The flow regimes of planar opposed jets at various exit air velocities, nozzle separations, excitation frequencies, and excitation amplitudes have been identified by a flow visualization technique combining with a high-speed camera. Results show that planar opposed jets exhibit horizontal instability at L/H ≤ 4 (where L is the nozzle separation and H is the slit height of the planar nozzle) and deflecting oscillation at L/H ≥ 6. The deflecting oscillation is originally started by the antisymmetric structures in the planar jets and is self-sustained by the periodic changes of the velocity field and the pressure field. At L/H ≤ 4, the acoustic excitation results in the horizontal periodic oscillation, whose frequency is equal to the excitation frequency. The acoustic excitation of oscillation amplitude less than 10% has negligible influence on the deflecting oscillation; for synchronous or asynchronous excitation with higher amplitude, the transition from the deflecting oscillation to a steady state or horizontal oscillation occurs.

  2. Acoustics of Excited Jets: A Historical Perspective

    NASA Technical Reports Server (NTRS)

    Brown, Cliffard A.

    2005-01-01

    The idea that a jet may be excited by external forcing is not new. The first published demonstration of a jet responding to external pressure waves occurred in the mid-1800's. It was not, however, until the 1950's, with the advent of commercial jet aircraft, that interest in the subject greatly increased. Researchers first used excited jets to study the structure of the jet and attempt to determine the nature of the noise sources. The jet actuators of the time limited the range (Reynolds and Mach numbers) of jets that could be excited. As the actuators improved, more realistic jets could be studied. This has led to a better understanding of how jet excitation may be used not only as a research tool to understand the flow properties and noise generation process, but also as a method to control jet noise.

  3. ATK Launch Vehicle (ALV-X1) Liftoff Acoustic Environments: Prediction vs. Measurement

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, Douglas; Kenny, Jeremy; Murphy, John

    2009-01-01

    The ATK Launch Vehicle (ALV-X1) provided an opportunity to measure liftoff acoustic noise data. NASA Marshall Space Flight Center (MSFC) engineers were interested in the ALV-X1 launch because the First Stage motor and launch pad conditions, including a relativity short deflector ducting, provide a potential analogue to future Ares I launches. This paper presents the measured liftoff acoustics on the vehicle and tower. Those measured results are compared to predictions based upon the method described in NASA SP-8072 "Acoustic Loads Generated by the Propulsion System" and the Vehicle Acoustic Environment Prediction Program (VAEPP) which was developed by MSFC acoustics engineers. One-third octave band sound pressure levels will be presented. This data is useful for the ALV-X1 in validating the pre-launch environments and loads predictions. Additionally, the ALV-X1 liftoff data can be scaled to define liftoff environments for the NASA Constellation program Ares vehicles. Vehicle liftoff noise is caused by the supersonic jet flow interaction with surrounding atmosphere or more simply, jet noise. As the vehicle's First Stage motor is ignited, an acoustic noise field is generated by the exhaust. This noise field persists due to the supersonic jet noise and reflections from the launch pad and tower, then changes as the vehicle begins to liftoff from the launch pad. Depending on launch pad and adjacent tower configurations, the liftoff noise is generally very high near the nozzle exit and decreases rapidly away from the nozzle. The liftoff acoustic time range of interest is typically 0 to 20 seconds after ignition. The exhaust plume thermo-fluid mechanics generates sound at approx.10 Hz to 20 kHz. Liftoff acoustic noise is usually the most severe dynamic environment for a launch vehicle or payload in the mid to high frequency range (approx.50 to 2000 Hz). This noise environment can induce high-level vibrations along the external surfaces of the vehicle and surrounding

  4. Development of Modeling Capabilities for Launch Pad Acoustics and Ignition Transient Environment Prediction

    NASA Technical Reports Server (NTRS)

    West, Jeff; Strutzenberg, Louise L.; Putnam, Gabriel C.; Liever, Peter A.; Williams, Brandon R.

    2012-01-01

    This paper presents development efforts to establish modeling capabilities for launch vehicle liftoff acoustics and ignition transient environment predictions. Peak acoustic loads experienced by the launch vehicle occur during liftoff with strong interaction between the vehicle and the launch facility. Acoustic prediction engineering tools based on empirical models are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. Modeling approaches are needed that capture the important details of the plume flow environment including the ignition transient, identify the noise generation sources, and allow assessment of the effects of launch pad geometric details and acoustic mitigation measures such as water injection. This paper presents a status of the CFD tools developed by the MSFC Fluid Dynamics Branch featuring advanced multi-physics modeling capabilities developed towards this goal. Validation and application examples are presented along with an overview of application in the prediction of liftoff environments and the design of targeted mitigation measures such as launch pad configuration and sound suppression water placement.

  5. Acoustic environment resulting in interaction of launch vehicle main engines jets with a launch pad having closed long ducts like a tunnel

    NASA Astrophysics Data System (ADS)

    Kudryavtsev, V. V.; Safronov, A. V.

    2012-01-01

    Paper deals with elaboration of semiempirical technique for prediction of broadband acoustic field generated at interaction of launch vehicle main engines jets with a launch pad having closed long ducts like a tunnel. Approach to a problem is based on analysis of jet interaction with typical deflectors, extraction of characteristic noise generation regions, and substitution of each region of noise generation by a system of independent acoustic sources with prescribed acoustic power and spectrum of acoustic radiation. Comparisons of calculated results with experimental data indicate that the technique allows to make reliable estimations of acoustical field characteristics as a function of geometrical and gasdynamic parameters and to analyze different means for reduction of acoustic loading at lift-off. Use of elaborated technique for multibody launch vehicles with clustered engines and multiduct launch pads is considered.

  6. Investigation of Acoustic Fields for the Cassini Spacecraft: Reverberant Versus Launch Environments

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; Himelblau, Harry

    2000-01-01

    The characterization and understanding of the acoustic field within a launch vehicle's payload fairing (PLF) is critical to the qualification of a spacecraft and ultimately to the success of its mission. Acoustic measurements taken recently for the Cassini mission have allowed unique opportunities to advance the aerospace industry's knowledge in this field. Prior to its launch, the expected liftoff acoustic environment of the spacecraft was investigated in a full-scale acoustic test of a Titan IV PLF and Cassini simulator in a reverberant test chamber. A major goal of this acoustic ground test was to quantify and verify the noise reduction performance of special barrier blankets that were designed especially to reduce the Cassirii acoustic environment. This paper will describe both the ground test and flight measurements, and compare the Cassini acoustic environment measured during launch with that measured earlier in the ground test. Special emphasis will be given to the noise reduction performance of the barrier blankets and to the acoustic coherence measured within the PLF.

  7. Laboratory Observations of Self-Excited Dust Acoustic Shocks

    NASA Astrophysics Data System (ADS)

    Heinrich, J.; Kim, S.-H.; Merlino, R. L.

    2009-09-01

    Repeated, self-excited dust acoustic shock waves (DASWs) have been observed in a dc glow discharge dusty plasma using high-speed video imaging. Two major observations are reported: (1) The self-steepening of a nonlinear dust acoustic wave (DAW) into a saw-tooth wave with sharp gradient in dust density, very similar to those found in numerical solutions of the fully nonlinear fluid equations for a nondispersive DAW [B. Eliasson and P. K. Shukla, Phys. Rev. E 69, 067401 (2004)], and (2) the collision and confluence of two DASWs.

  8. Acoustical scattering cross section of gas bubbles under dual-frequency acoustic excitation.

    PubMed

    Zhang, Yuning; Li, Shengcai

    2015-09-01

    The acoustical scattering cross section is a paramount parameter determining the scattering ability of cavitation bubbles when they are excited by the incident acoustic waves. This parameter is strongly related with many important applications of acoustic cavitation including facilitating the reaction of chemical process, boosting bubble sonoluminescence, and performing non-invasive therapy and drug delivery. In present paper, both the analytical and numerical solutions of acoustical scattering cross section of gas bubbles under dual-frequency excitation are obtained. The validity of the analytical solution is shown with demonstrating examples. The nonlinear characteristics (e.g., harmonics, subharmonics and ultraharmonics) of the scattering cross section curve under dual-frequency approach are investigated. Compared with single-frequency approach, the dual-frequency approach displays more resonances termed as "combination resonances" and could promote the acoustical scattering cross section significantly within a much broader range of bubble sizes due to the generation of more resonances. The influence of several paramount parameters (e.g., acoustic pressure amplitude, power allocations between two acoustic components, and the ratio of the frequencies) in the dual-frequency system on the predictions of scattering cross section has been discussed.

  9. The acoustic excitation of air bubbles fragmenting in sheared flow.

    PubMed

    Deane, Grant B; Stokes, M Dale

    2008-12-01

    An analysis of the acoustic emissions of air bubbles fragmenting in sheared fluid flow is presented. The fragmentation of bubbles into two products only is considered. While the measured pressure amplitude is highly variable, the partition of energy between fragmentation products is highly correlated. The partition of energy between products is, on average, approximately equal irrespective of the relative sizes of the bubble products. This observation suggests that the acoustic excitation mechanism is common to both bubbles immediately prior to fragmentation. A model for the excitation mechanism based on symmetric collapse of the neck of air joining fragmentation products is proposed and found to be sufficient to explain the range of observed bubble pulse amplitudes and the equal partition of energy.

  10. Synchronization of self-excited dust acoustic waves

    NASA Astrophysics Data System (ADS)

    Suranga Ruhunusiri, W. D.; Goree, John

    2012-10-01

    Synchronization is a nonlinear phenomenon where a self-excited oscillation, like a wave in a plasma, interacts with an external driving, resulting in an adjustment of the oscillation frequency. Dust acoustic wave synchronization has been experimentally studied previously in laboratory and in microgravity conditions, e.g. [Pilch PoP 2009] and [Menzel PRL 2010]. We perform a laboratory experiment to study synchronization of self-excited dust acoustic waves. An rf glow discharge argon plasma is formed by applying a low power radio frequency voltage to a lower electrode. A 3D dust cloud is formed by levitating 4.83 micron microspheres inside a glass box placed on the lower electrode. Dust acoustic waves are self-excited with a natural frequency of 22 Hz due to an ion streaming instability. A cross section of the dust cloud is illuminated by a vertical laser sheet and imaged from the side with a digital camera. To synchronize the waves, we sinusoidally modulate the overall ion density. Differently from previous experiments, we use a driving electrode that is separate from the electrode that sustains the plasma, and we characterize synchronization by varying both driving amplitude and frequency.

  11. Characterization of Pump-Induced Acoustics in Space Launch System Main Propulsion System Liquid Hydrogen Feedline Using Airflow Test Data

    NASA Technical Reports Server (NTRS)

    Eberhart, C. J.; Snellgrove, L. M.; Zoladz, T. F.

    2015-01-01

    High intensity acoustic edgetones located upstream of the RS-25 Low Pressure Fuel Turbo Pump (LPFTP) were previously observed during Space Launch System (STS) airflow testing of a model Main Propulsion System (MPS) liquid hydrogen (LH2) feedline mated to a modified LPFTP. MPS hardware has been adapted to mitigate the problematic edgetones as part of the Space Launch System (SLS) program. A follow-on airflow test campaign has subjected the adapted hardware to tests mimicking STS-era airflow conditions, and this manuscript describes acoustic environment identification and characterization born from the latest test results. Fluid dynamics responsible for driving discrete excitations were well reproduced using legacy hardware. The modified design was found insensitive to high intensity edgetone-like discretes over the bandwidth of interest to SLS MPS unsteady environments. Rather, the natural acoustics of the test article were observed to respond in a narrowband-random/mixed discrete manner to broadband noise thought generated by the flow field. The intensity of these responses were several orders of magnitude reduced from those driven by edgetones.

  12. Feasibility of using piezoelectric actuators to control launch vehicle acoustics and structural vibrations

    NASA Astrophysics Data System (ADS)

    Niezrecki, Christopher; Cudney, Harley H.

    2000-06-01

    Future launch vehicle payload fairings will be manufactured form advanced lightweight composite materials. The loss of distributed mass causes a significant increase in the internal acoustic environment, causing a severe threat to the payload. Using piezoelectric actuators to control the fairing vibration and the internal acoustic environment has been proposed. To help determine the acoustic control authority of piezoelectric actuators mounted on a rocket fairing, the internal acoustic response created by the actuators needs to be determined. In this work, the internal acoustic response of a closed simply-supported (SS) cylinder actuated by piezoelectric (PZT) actuators is determined using a n impedance model for the actuator and boundary element analysis. The experimentally validated model is used to extrapolate results for a SS cylinder that emulates a Minotaur payload fairing. The internal cylinder acoustic levels are investigated for PZT actuation between 35 and 400 Hz. Significant reductions in the structural response due to increased damping do not equate to similar reductions in the acoustic SPLs for the cylinder. The sound levels at the acoustic resonant frequencies are essentially unaffected by the significant increase in structural damping while the acoustic level sat the structural resonant frequencies are mildly reduced. The interior acoustic response of the cylinder is dominated by the acoustic modes and therefore significant reductions in the overall interior acoustic levels will not be achieved if only the structural resonances are controlled. As the actuation frequency is reduced, the number of actuators required to generate acoustic levels commensurate to that found in the fairing increases to impractical values. Below approximately 100 Hz, the current demands reach levels that are extremely difficult to achieve with a practical system. The results of this work imply that PZT actuators do not have the authority to control the payload fairing

  13. Vibro-Acoustic Analysis of NASA's Space Shuttle Launch Pad 39A Flame Trench Wall

    NASA Technical Reports Server (NTRS)

    Margasahayam, Ravi N.

    2009-01-01

    A vital element to NASA's manned space flight launch operations is the Kennedy Space Center Launch Complex 39's launch pads A and B. Originally designed and constructed In the 1960s for the Saturn V rockets used for the Apollo missions, these pads were modified above grade to support Space Shuttle missions. But below grade, each of the pad's original walls (including a 42 feet deep, 58 feet wide, and 450 feet long tunnel designed to deflect flames and exhaust gases, the flame trench) remained unchanged. On May 31, 2008 during the launch of STS-124, over 3500 of the. 22000 interlocking refractory bricks that lined east wall of the flame trench, protecting the pad structure were liberated from pad 39A. The STS-124 launch anomaly spawned an agency-wide initiative to determine the failure root cause, to assess the impact of debris on vehicle and ground support equipment safety, and to prescribe corrective action. The investigation encompassed radar imaging, infrared video review, debris transport mechanism analysis using computational fluid dynamics, destructive testing, and non-destructive evaluation, including vibroacoustic analysis, in order to validate the corrective action. The primary focus of this paper is on the analytic approach, including static, modal, and vibro-acoustic analysis, required to certify the corrective action, and ensure Integrity and operational reliability for future launches. Due to the absence of instrumentation (including pressure transducers, acoustic pressure sensors, and accelerometers) in the flame trench, defining an accurate acoustic signature of the launch environment during shuttle main engine/solid rocket booster Ignition and vehicle ascent posed a significant challenge. Details of the analysis, including the derivation of launch environments, the finite element approach taken, and analysistest/ launch data correlation are discussed. Data obtained from the recent launch of STS-126 from Pad 39A was instrumental in validating the

  14. Problem of intensity reduction of acoustic fields generated by gas-dynamic jets of motors of the rocket-launch vehicles at launch

    NASA Astrophysics Data System (ADS)

    Vorobyov, A. M.; Abdurashidov, T. O.; Bakulev, V. L.; But, A. B.; Kuznetsov, A. B.; Makaveev, A. T.

    2015-04-01

    The present work experimentally investigates suppression of acoustic fields generated by supersonic jets of the rocket-launch vehicles at the initial period of launch by water injection. Water jets are injected to the combined jet along its perimeter at an angle of 0° and 60°. The solid rocket motor with the rocket-launch vehicles simulator case is used at tests. Effectiveness of reduction of acoustic loads on the rocket-launch vehicles surface by way of creation of water barrier was proved. It was determined that injection angle of 60° has greater effectiveness to reduce pressure pulsation levels.

  15. Acoustic excitation of liquid fuel droplets and coaxial jets

    NASA Astrophysics Data System (ADS)

    Rodriguez, Juan Ignacio

    This experimental study focuses on two important problems relevant to acoustic coupling with condensed phase transport processes, with special relevance to liquid rocket engine and airbreathing engine combustion instabilities. The first part of this dissertation describes droplet combustion characteristics of various fuels during exposure to external acoustical perturbations. Methanol, ethanol, a liquid synthetic fuel derived from coal gasification via the Fischer-Tropsch process, and a blend of aviation fuel and the synthetic fuel are used. During acoustic excitation, the droplet is situated at or near a pressure node condition, where the droplet experiences the largest velocity perturbations, and at or near a pressure antinode condition, where the droplet is exposed to minimal velocity fluctuations. For unforced conditions, the values of the droplet burning rate constant K of the different fuels are consistent with data in the literature. The location of the droplet with respect to a pressure node or antinode also has a measurable effect on droplet burning rates, which are different for different fuels and in some cases are as high as 28% above the unforced burning rate value. Estimates of flame extinction due to acoustic forcing for different fuels are also obtained. The second part of this work consists of an experimental study on coaxial jet behavior under non-reactive, cryogenic conditions, with direct applications to flow mixing and unstable behavior characterization in liquid rocket engines. These experiments, conducted with nitrogen, span a range of outer to inner jet momentum flux ratios from 0.013 to 23, and explore subcritical, nearcritical and supercritical pressure conditions, with and without acoustic excitation, for two injector geometries. Acoustic forcing at 3 kHz is utilized to maximize the pressure fluctuations within the chamber acting on the jet, reaching maximum values of 4% of the mean chamber pressure. The effect of the magnitude and phase

  16. A passively tunable acoustic metamaterial lens for selective ultrasonic excitation

    SciTech Connect

    Zhu, H.; Semperlotti, F.

    2014-09-07

    In this paper, we present an approach to ultrasonic beam-forming and beam-steering in structures based on the concept of embedded acoustic metamaterial lenses. The lens design exploits the principle of acoustic drop-channel that enables the dynamic coupling of multiple ultrasonic waveguides at selected frequencies. In contrast with currently available technology, the embedded lens allows exploiting the host structure as a key component of the transducer system therefore enabling directional excitation by means of a single ultrasonic transducer. The design and the performance of the lens are numerically investigated by using Plane Wave Expansion and Finite Difference Time Domain techniques applied to bulk structures. Then, the design is experimentally validated on a thin aluminum plate waveguide where the lens is implemented by through-holes. The dynamic response of the embedded lens is estimated by reconstructing, via Laser Vibrometry, the velocity field induced by a single source located at the center of the lens.

  17. Enhanced viscous flow drag reduction using acoustic excitation

    NASA Technical Reports Server (NTRS)

    Nagel, Robert T.

    1987-01-01

    Proper acoustic excitation of a single large-eddy break-up device can increase the resulting drag reduction and, after approximately 40 to 50 delta downstream, provide net drag reduction. Precise optimization of the input time delay, amplitude and response threshold is difficult but possible to achieve. Drag reduction is improved with optimized conditions. The possibility of optimized processing strongly suggests a mechanism which involves interaction of the acoustic waves and large eddies at the trailing edge of the large eddy break-up device. Although the mechanism for spreading of this phenomenon is unknown, it is apparent that the drag reduction effect does tend to spread spanwise as the flow convects downstream. The phenomenon is not unique to a particular blade configuration or flow velocity, although all data have been obtained at relatively low Reynolds numbers. The general repeatibility of the results for small configuration changes serves as verification of the phenomenon.

  18. Fast excitation of geodesic acoustic mode by energetic particle beams

    NASA Astrophysics Data System (ADS)

    Cao, Jintao; Qiu, Zhiyong; Zonca, Fulvio

    2015-12-01

    A new mechanism for geodesic acoustic mode (GAM) excitation by a not fully slowed down energetic particle (EP) beam is analyzed to explain experimental observations in Large Helical Device. It is shown that the positive velocity space gradient near the lower-energy end of the EP distribution function can strongly drive the GAM unstable. The new features of this EP-induced GAM (EGAM) are: (1) no instability threshold in the pitch angle; (2) the EGAM frequency can be higher than the local GAM frequency; and (3) the instability growth rate is much larger than that driven by a fully slowed down EP beam.

  19. Fast excitation of geodesic acoustic mode by energetic particle beams

    SciTech Connect

    Cao, Jintao; Qiu, Zhiyong; Zonca, Fulvio

    2015-12-15

    A new mechanism for geodesic acoustic mode (GAM) excitation by a not fully slowed down energetic particle (EP) beam is analyzed to explain experimental observations in Large Helical Device. It is shown that the positive velocity space gradient near the lower-energy end of the EP distribution function can strongly drive the GAM unstable. The new features of this EP-induced GAM (EGAM) are: (1) no instability threshold in the pitch angle; (2) the EGAM frequency can be higher than the local GAM frequency; and (3) the instability growth rate is much larger than that driven by a fully slowed down EP beam.

  20. Bubble dynamics under acoustic excitation with multiple frequencies

    NASA Astrophysics Data System (ADS)

    Zhang, Y. N.; Zhang, Y. N.; Li, S. C.

    2015-01-01

    Because of its magnificent mechanical and chemical effects, acoustic cavitation plays an important role in a broad range of biomedical, chemical and mechanical engineering problems. Particularly, irradiation of the multiple frequency acoustic wave could enhance the effects of cavitation. The advantages of employment of multi-frequency ultrasonic field include decreasing the cavitation thresholds, promoting cavitation nuclei generation, increasing the mass transfer and improving energy efficiency. Therefore, multi-frequency ultrasonic systems are employed in a variety of applications, e.g., to enhance the intensity of sonoluminenscence, to increase efficiency of sonochemical reaction, to improve the accuracy of ultrasound imaging and the efficiency of tissue ablation. Compared to single-frequency systems, a lot of new features of bubble dynamics exist in multi-frequency systems, such as special properties of oscillating bubbles, unique resonances in the bubble response curves, and unusual chaotic behaviours. In present paper, the underlying mechanisms of the cavitation effects under multi-frequency acoustical excitation are also briefly introduced.

  1. Detection and classification of indoor objects using acoustic excitations

    NASA Astrophysics Data System (ADS)

    Setlur, Pawan; Amin, Moeness G.; Zoubir, Abdelhak M.

    2009-05-01

    In this paper, we show that objects of interest, like pipes and cylinders, reminiscent of guns and rifles, can be classified based on their acoustic vibration signatures. That is, if the acoustic returns are measurable, one can indeed classify objects based on the physical principle of resonance. We consider classifiers which are both training independent and those that are training dependent. The statistical classifier belongs to the former category, whereas, the neural network classifier belongs to the latter. Comparisons between the two approaches are shown to render both classifiers as suitable classifiers with small classification errors. We use the probability of correct classification as a measure of performance. We demonstrate experimentally that unique features for classification are the resonant frequencies. The measured data are obtained by exciting mechanical vibrations in pipes of different lengths and of different metals, for example, copper, aluminum, and steel, and the measuring of the acoustic returns, using a simple microphone. Autoregressive modeling is applied to the data to extract the respective object features, namely, the vibration frequencies and damping values. We consider two classification problems, 1) Classifying objects comprised of different metals, and 2) Classifying objects of the same material, but made of different lengths. It is shown that classification performance can be improved by incorporating additional features such as the damping coefficients.

  2. Excitation of Ion Acoustic Waves by Electron Beams

    NASA Astrophysics Data System (ADS)

    Sydorenko, Dmytro; Tokluoglu, Erinc; Kaganovich, Igor; Startsev, Edward; Davidson, Ronald

    2012-10-01

    The interaction of electron beams with plasmas is of considerable importance particularly for hybrid DC/RF coupled plasma sources used in plasma processing [1]. An electron beam is formed by emission from one surface, is accelerated through a dc bias electric field and enters the bulk plasma. Emitted electrons excite electron plasma (Langmuir) waves through the two-stream instability. Due to the high localized plasmon pressure, ion acoustic waves are excited parametrically. The plasma waves saturate by non-linear wave trapping. Eventually coupling between electron plasma waves and ion acoustic waves deteriorates the Langmuir waves, which leads to a bursting behavior. The two-stream instability and the consequent ion fluctuations are studied over a wide range of system parameters using the particle-in-cell codes EDIPIC and LSP. The influenceof these instabilities on collisionless electron heating are presented for a hybrid RF-DC plasma source.[4pt] [1] Lin Xu, et al, Appl. Phys. Lett., 93, 261502 (2008).

  3. FROM THE CURRENT LITERATURE: Laser excitation of surface acoustic waves: a new direction in opto-acoustic spectroscopy of a solid

    NASA Astrophysics Data System (ADS)

    Karabutov, Aleksander A.

    1985-11-01

    Studies in thermo-optic excitation of surface acoustic waves are reviewed. The excitation of periodic and pulse signals is discussed, using nonmoving and moving beams. Most attention is paid to application of this effect for purposes of opto-acoustic spectroscopy of a solid. The possibilities and promises of using opto-acoustic spectroscopy (OAS) employing surface acoustic waves (SAW) are analyzed

  4. Synchrotron x-ray imaging of acoustic cavitation bubbles induced by acoustic excitation

    NASA Astrophysics Data System (ADS)

    Jung, Sung Yong; Park, Han Wook; Park, Sung Ho; Lee, Sang Joon

    2017-04-01

    The cavitation induced by acoustic excitation has been widely applied in various biomedical applications because cavitation bubbles can enhance the exchanges of mass and energy. In order to minimize the hazardous effects of the induced cavitation, it is essential to understand the spatial distribution of cavitation bubbles. The spatial distribution of cavitation bubbles visualized by the synchrotron x-ray imaging technique is compared to that obtained with a conventional x-ray tube. Cavitation bubbles with high density in the region close to the tip of the probe are visualized using the synchrotron x-ray imaging technique, however, the spatial distribution of cavitation bubbles in the whole ultrasound field is not detected. In this study, the effects of the ultrasound power of acoustic excitation and working medium on the shape and density of the induced cavitation bubbles are examined. As a result, the synchrotron x-ray imaging technique is useful for visualizing spatial distributions of cavitation bubbles, and it could be used for optimizing the operation conditions of acoustic cavitation.

  5. Radial structures and nonlinear excitation of geodesic acoustic modes

    NASA Astrophysics Data System (ADS)

    Zonca, F.; Chen, L.

    2008-08-01

    Geodesic acoustic modes (GAM) are shown to constitute a continuous spectrum due to radial inhomogeneities. The importance and theoretical as well as experimental implications of this fact are discussed in this work. The existence of a singular layer causes GAM to mode convert to short-wavelength kinetic GAM (KGAM) via finite ion Larmor radii; analogous to kinetic Alfvén waves (KAW). Furthermore, it is shown that KGAM can be nonlinearly excited by drift-wave (DW) turbulence via 3-wave parametric interactions, and the resultant driven-dissipative nonlinear system exhibits typical prey-predator self-regulatory dynamics, consistent with recent experimental observations on HL-2A. The degeneracy of GAM/KGAM with beta-induced Alfvén eigenmodes (BAE) is demonstrated and discussed, with emphasis on its important role in the complex self-organized behaviors of burning plasmas.

  6. Forced response sound radiation from acoustically or mechanically excited small plates

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    1992-01-01

    Sound radiation from an acoustically excited, clamped aluminum plate is measured and expressed in terms of noise reduction to take into account the incident acoustic excitation field. Its mode shapes and modal frequencies are measured and show good agreement with the predictions from a finite element MSC/NASTRAN model. Noise reduction is measured at 15 points behind the plate and demonstrate good agreement with predictions employing the SYSNOISE numerical analysis system for acoustic-structure interaction.

  7. Forced response sound radiation from acoustically or mechanically excited small plates

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    1992-01-01

    Sound radiation from an acoustically excited, clamped aluminum plate is measured and expressed in terms of noise reduction to take into account the incident acoustic excitation field. Its mode shapes and modal frequencies are measured and show good agreement with the predictions from a finite element MSC/NASTRAN model. Noise reduction is measured at 15 points behind the plate and demonstrate good agreement with predictions employing the SYSNOISE numerical analysis system for acoustic-structure interaction.

  8. Simulation of Shuttle launch G forces and acoustic loads using the NASA Ames Research Center 20G centrifuge

    NASA Technical Reports Server (NTRS)

    Shaw, T. L.; Corliss, J. M.; Gundo, D. P.; Mulenburg, G. M.; Breit, G. A.; Griffith, J. B.

    1994-01-01

    The high cost and long times required to develop research packages for space flight can often be offset by using ground test techniques. This paper describes a space shuttle launch and reentry simulating using the NASA Ames Research Center's 20G centrifuge facility. The combined G-forces and acoustic environment during shuttle launch and landing were simulated to evaluate the effect on a payload of laboratory rates. The launch G force and acoustic profiles are matched to actual shuttle launch data to produce the required G-forces and acoustic spectrum in the centrifuge test cab where the rats were caged on a free-swinging platform. For reentry, only G force is simulated as the aero-acoustic noise is insignificant compared to that during launch. The shuttle G-force profiles of launch and landing are achieved by programming the centrifuge drive computer to continuously adjust centrifuge rotational speed to obtain the correct launch and landing G forces. The shuttle launch acoustic environment is simulated using a high-power, low-frequency audio system. Accelerometer data from STS-56 and microphone data from STS-1 through STS-5 are used as baselines for the simulations. This paper provides a description of the test setup and the results of the simulation with recommendations for follow-on simulations.

  9. A large-amplitude traveling ionospheric disturbance excited by the space shuttle during launch

    SciTech Connect

    Noble, S.T. )

    1990-11-01

    The ionosphere was monitored during the fourth space shuttle (STS 4) launch in June 1982 by the Arecibo incoherent scatter radar. A long-lived, large-amplitude, traveling ionospheric disturbance with dominant wave moles of {approximately} 15 and 75 min was observed shortly after the launch. The disturbance wave train is likely the product of a variety of wave modes. The disturbance front traveled with an average group speed of >628 m/s. Such speeds are typical of fast moving shock waves and ducted gravity waves. Either one or both could be responsible for the signatures observed near the leading edge of the STS 4 wave train. Later arriving waves, with their inherently lower propagation speeds, are attributed to additional gravity wave modes. These waves, however, were not explicitly identified in this study. Although atmospheric waves are excited along the entire flight path, the most intense region of excitation is located along a relatively short flight segment ({approximately}70 km) near the launch site where all primary thrusters are firing and over 70% of the propellants are expended. Not since the nuclear bomb tests of the late 1950s and early 1960s has an artificial source of atmospheric gravity waves been more available for upper atmospheric studies. The routine launching of high thrust vehicles provides an excellent opportunity to observe the propagation characteristics of atmospheric waves under controlled conditions and to acquire information on the nature of the upper atmosphere.

  10. Vibroacoustic analysis and experimental validation of the structural responses of NASA Mars Exploration Rover spacecraft due to acoustic launch load

    NASA Technical Reports Server (NTRS)

    Hwang, H. J.

    2003-01-01

    Structural responses of a spacecraft during liftoff are dominated by the intense acoustic pressure field imping on the exterior of the launch vehicle. Statistical Energy Analysis model of the NASA Mars Exploration Rover spacecraft has been developed and the SEA model was analyzed to predict vibroacoustic responses of the spacecraft under the diffuse acoustic loading condition.

  11. Acoustically levitated dancing drops: Self-excited oscillation to chaotic shedding

    NASA Astrophysics Data System (ADS)

    Lin, Po-Cheng; I, Lin

    2016-02-01

    We experimentally demonstrate self-excited oscillation and shedding of millimeter-sized water drops, acoustically levitated in a single-node standing waves cavity, by decreasing the steady acoustic wave intensity below a threshold. The perturbation of the acoustic field by drop motion is a possible source for providing an effective negative damping for sustaining the growing amplitude of the self-excited motion. Its further interplay with surface tension, drop inertia, gravity and acoustic intensities, select various self-excited modes for different size of drops and acoustic intensity. The large drop exhibits quasiperiodic motion from a vertical mode and a zonal mode with growing coupling, as oscillation amplitudes grow, until falling on the floor. For small drops, chaotic oscillations constituted by several broadened sectorial modes and corresponding zonal modes are self-excited. The growing oscillation amplitude leads to droplet shedding from the edges of highly stretched lobes, where surface tension no longer holds the rapid expanding flow.

  12. Acoustically levitated dancing drops: Self-excited oscillation to chaotic shedding.

    PubMed

    Lin, Po-Cheng; I, Lin

    2016-02-01

    We experimentally demonstrate self-excited oscillation and shedding of millimeter-sized water drops, acoustically levitated in a single-node standing waves cavity, by decreasing the steady acoustic wave intensity below a threshold. The perturbation of the acoustic field by drop motion is a possible source for providing an effective negative damping for sustaining the growing amplitude of the self-excited motion. Its further interplay with surface tension, drop inertia, gravity and acoustic intensities, select various self-excited modes for different size of drops and acoustic intensity. The large drop exhibits quasiperiodic motion from a vertical mode and a zonal mode with growing coupling, as oscillation amplitudes grow, until falling on the floor. For small drops, chaotic oscillations constituted by several broadened sectorial modes and corresponding zonal modes are self-excited. The growing oscillation amplitude leads to droplet shedding from the edges of highly stretched lobes, where surface tension no longer holds the rapid expanding flow.

  13. System And Method For Characterizing Voiced Excitations Of Speech And Acoustic Signals, Removing Acoustic Noise From Speech, And Synthesizi

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-04-25

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  14. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-08-08

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  15. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2004-03-23

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  16. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2006-02-14

    The present invention is a system and method for characterizing human (or animate) speech voiced excitation functions and acoustic signals, for removing unwanted acoustic noise which often occurs when a speaker uses a microphone in common environments, and for synthesizing personalized or modified human (or other animate) speech upon command from a controller. A low power EM sensor is used to detect the motions of windpipe tissues in the glottal region of the human speech system before, during, and after voiced speech is produced by a user. From these tissue motion measurements, a voiced excitation function can be derived. Further, the excitation function provides speech production information to enhance noise removal from human speech and it enables accurate transfer functions of speech to be obtained. Previously stored excitation and transfer functions can be used for synthesizing personalized or modified human speech. Configurations of EM sensor and acoustic microphone systems are described to enhance noise cancellation and to enable multiple articulator measurements.

  17. On the correlation of plume centerline velocity decay of turbulent acoustically excited jets

    NASA Technical Reports Server (NTRS)

    Vonglahn, Uwe H.

    1987-01-01

    Acoustic excitation was shown to alter the velocity decay and spreading characteristics of jet plumes by modifying the large-scale structures in the plume shear layer. The present work consists of reviewing and analyzing available published and unpublished experimental data in order to determine the importance and magnitude of the several variables that contribute to plume modification by acoustic excitation. Included in the study were consideration of the effects of internal and external acoustic excitation, excitation Strouhal number, acoustic excitation level, nozzle size, and flow conditions. The last include jet Mach number and jet temperature. The effects of these factors on the plume centerline velocity decay are then summarized in an overall empirical correlation.

  18. The use of coherence functions to determine dynamic excitation sources on launch vehicle payloads

    NASA Technical Reports Server (NTRS)

    Barrett, S.; Halvorson, R. M.

    1979-01-01

    The problem of determining the relative contribution of simultaneous acoustic and mechanical inputs to the response of structures under combined dynamic loads was studied. An analytical technique developed by Bendat for calculating ordinary, partial, and multiple coherence functions, using an iterative nonmatrix approach was applied to data obtained from laboratory tests on a complex structural assembly. Testing was performed in an acoustically 'live' room. Up to three random inputs, having similar spectral content and varying degrees of mutual coherence, and a single output were used. Stationary and nonstationary inputs were used. It was concluded that the technique provided an effective method of identifying sources of dynamic excitation and evaluating their relative contributions to the measured output at structural resonances, for stationary random inputs. An attempt to apply the technique to nonstationary inputs did not yield consistent results.

  19. Nonlinear acoustic propagation of launch vehicle and military jet aircraft noise

    NASA Astrophysics Data System (ADS)

    Gee, Kent L.

    2010-10-01

    The noise from launch vehicles and high-performance military jet aircraft has been shown to travel nonlinearly as a result of an amplitude-dependent speed of sound. Because acoustic pressure compressions travel faster than rarefactions, the waveform steepens and shocks form. This process results in a very different (and readily audible) noise signature and spectrum than predicted by linear models. On-going efforts to characterize the nonlinearity using statistical and spectral measures are described with examples from recent static tests of solid rocket boosters and the F-22 Raptor.

  20. Validation of High-Fidelity CFD/CAA Framework for Launch Vehicle Acoustic Environment Simulation against Scale Model Test Data

    NASA Technical Reports Server (NTRS)

    Liever, Peter A.; West, Jeffrey S.; Harris, Robert E.

    2016-01-01

    A hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) modeling framework has been developed for launch vehicle liftoff acoustic environment predictions. The framework couples the existing highly-scalable NASA production CFD code, Loci/CHEM, with a high-order accurate Discontinuous Galerkin solver developed in the same production framework, Loci/THRUST, to accurately resolve and propagate acoustic physics across the entire launch environment. Time-accurate, Hybrid RANS/LES CFD modeling is applied for predicting the acoustic generation physics at the plume source, and a high-order accurate unstructured mesh Discontinuous Galerkin (DG) method is employed to propagate acoustic waves away from the source across large distances using high-order accurate schemes. The DG solver is capable of solving 2nd, 3rd, and 4th order Euler solutions for non-linear, conservative acoustic field propagation. Initial application testing and validation has been carried out against high resolution acoustic data from the Ares Scale Model Acoustic Test (ASMAT) series to evaluate the capabilities and production readiness of the CFD/CAA system to resolve the observed spectrum of acoustic frequency content. This paper presents results from this validation and outlines efforts to mature and improve the computational simulation framework.

  1. Validation of High-Fidelity CFD/CAA Framework for Launch Vehicle Acoustic Environment Simulation against Scale Model Test Data

    NASA Technical Reports Server (NTRS)

    Liever, Peter A.; West, Jeffrey S.

    2016-01-01

    A hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) modeling framework has been developed for launch vehicle liftoff acoustic environment predictions. The framework couples the existing highly-scalable NASA production CFD code, Loci/CHEM, with a high-order accurate discontinuous Galerkin solver developed in the same production framework, Loci/THRUST, to accurately resolve and propagate acoustic physics across the entire launch environment. Time-accurate, Hybrid RANS/LES CFD modeling is applied for predicting the acoustic generation physics at the plume source, and a high-order accurate unstructured discontinuous Galerkin (DG) method is employed to propagate acoustic waves away from the source across large distances using high-order accurate schemes. The DG solver is capable of solving 2nd, 3rd, and 4th order Euler solutions for non-linear, conservative acoustic field propagation. Initial application testing and validation has been carried out against high resolution acoustic data from the Ares Scale Model Acoustic Test (ASMAT) series to evaluate the capabilities and production readiness of the CFD/CAA system to resolve the observed spectrum of acoustic frequency content. This paper presents results from this validation and outlines efforts to mature and improve the computational simulation framework.

  2. The use of GPS arrays in detecting shock-acoustic waves generated during rocket launchings

    NASA Astrophysics Data System (ADS)

    Afraimovich, E. L.; Kosogorov, E. A.; Perevalova, N. P.; Plotnikov, A. V.

    2001-12-01

    This paper is concerned with the parameters of shock-acoustic waves (SAW) generated during rocket launchings. We have developed the interferometric method for determining SAW parameters (including angular characteristics of the wave vector, and the SAW phase velocity, as well as the direction towards the source) using GPS-arrays. Contrary to the conventional radio-probing techniques, the proposed method provides an estimate of SAW parameters without a priori information about the site and time of a rocket launching. The application of the method is illustrated by a case study of ionospheric effects from launchings of rockets PROTON, SOYUZ and SPACE SHUTTLE from Baikonur and Kennedy Space Center cosmodromes in 1998-2000. In spite of a difference of rocket characteristics, the ionospheric response for all launchings had the character of an /N-wave corresponding to the form of a shock wave. The SAW period /T is 270-360s, and the amplitude exceeds the standard deviation of total electron content background fluctuations in this range of periods under quiet and moderate geomagnetic conditions by factors of 2-5 as a minimum. The angle of elevation of the SAW wave vector varies from /30° to /60°, and the SAW phase velocity (900-1200m/s) approaches the sound velocity at heights of the ionospheric /F-region maximum. The position of the SAW source, inferred by neglecting refraction corrections, corresponds to the segment of the rockets path at a distance no less than 200-900km from the launch pad, and to the rocket flying altitude no less than 100km. Our data are consistent with the existing view that SAW are generated during a nearly horizontal flight of the rocket with its engine in operation in the acceleration segment of the path at 100-130km altitudes in the lower atmosphere.

  3. Spontaneous excitations of low amplitude hole filaments, acoustic vortices, and rogue wave events in weakly disordered dust acoustic waves

    NASA Astrophysics Data System (ADS)

    Tsai, Ya-Yi; Chang, Mei-Chu; Tsai, Jun-Yi; I, Lin

    2017-05-01

    In this work, we briefly review our recent experimental studies on the observations and waveform dynamics of spontaneous excitations of low and high amplitude singular objects: low amplitude hole filaments coinciding with the wiggling trajectories of topological defects surrounded by acoustic vortices with helical waveforms, and uncertain rogue wave events, in self-excited weakly disordered dust acoustic waves. The changes of waveform topology, caused by kinking, rupturing and reconnection of sequential wave crests surfaces, and the reversed process, are responsible for the chaotic creation, propagation, and annihilation of acoustic vortex pairs with opposite helicities winding around low amplitude hole filaments. The observed rogue wave events are preceded by a higher probability of surrounding defects. Particle focusing by the transverse electric forces from ruptured and tilted wave crests nearby defects are identified as the major cause for rogue wave generation.

  4. Passive control of flow-excited acoustic resonance in rectangular cavities using upstream mounted blocks

    NASA Astrophysics Data System (ADS)

    Shaaban, Mahmoud; Mohany, Atef

    2015-04-01

    A passive method for controlling the flow-excited acoustic resonance resulting from subsonic flows over rectangular cavities in channels is investigated. A cavity with length to depth ratio of is tested in air flow of Mach number up to 0.45. When the acoustic resonance is excited, the sound pressure level in the cavity reaches 162 dB. Square blocks are attached to the surface of the channel and centred upstream of the cavity leading edge to suppress the flow-excited acoustic resonance in the cavity. Six blocks of different widths are tested at three different upstream distances. The results show that significant attenuation of up to 30 dB of the excited sound pressure level is achieved using a block with a width to height ratio of 3, while blocks that fill the whole width of the channel amplify the pressure of the excited acoustic resonance. Moreover, it is found that placing the block upstream of the cavity causes the onset of the acoustic resonance to occur at higher flow velocities. In order to investigate the nature of the interactions that lead to suppression of the acoustic resonance and to identify the changes in flow patterns due to the placement of the block, 2D measurements of turbulence intensity in the shear layer and the block wake region are performed. The location of the flow reattachment point downstream of the block relative to the shear layer separation point has a major influence on the suppression level of the excited acoustic resonance. Furthermore, higher attenuation of noise is related to lower span-wise correlation of the shear-layer perturbation.

  5. Effects of vibration excitation methodology and configuration of an acoustic needle on its tip vibration.

    PubMed

    Li, Ning; Hu, Junhui

    2013-04-01

    One of design purposes of an acoustic needle is to obtain a big vibration displacement at its tip. In this paper, vibration characteristics of the tip of the acoustic needle driven by a sandwich type ultrasonic transducer, is investigated to obtain the guidelines for increasing the tip vibration. It is found that the tip vibration can be increased by employing acoustic needles with proper vibration excitation structure and configuration. The effective measures include using a sandwich type piezoelectric transducer with flexurally vibrating end plates and an acoustic needle with conical tip section, decreasing the length of vibration excitation section at the needle root, bonding the needle root at a proper location of the transducer end plate, and tuning the length ratio of the conical tip section to the whole needle.

  6. Excitation of geodesic acoustic modes by external fields.

    PubMed

    Hallatschek, K; McKee, G R

    2012-12-14

    It is planned to use external magnetic perturbations at acoustic frequencies at the DIII-D tokamak to attempt to drive geodesic acoustic modes (GAM) to modify the turbulent transport. We show that this might not only be possible--despite the well-known electrostatic nature of the GAMs--but might be a viable and efficient method to generate GAMs in magnetically confined plasmas, by developing an elegant analytic method which allows us to couple numerical dynamic equilibrium calculations with massively parallel non-Boussinesq turbulence code runs and yields practical estimates of the effectivity of the method.

  7. Combination and simultaneous resonances of gas bubbles oscillating in liquids under dual-frequency acoustic excitation.

    PubMed

    Zhang, Yuning; Zhang, Yuning; Li, Shengcai

    2017-03-01

    The multi-frequency acoustic excitation has been employed to enhance the effects of oscillating bubbles in sonochemistry for many years. In the present paper, nonlinear dynamic oscillations of bubble under dual-frequency acoustic excitation are numerically investigated within a broad range of parameters. By investigating the power spectra and the response curves of oscillating bubbles, two unique features of bubble oscillations under dual-frequency excitation (termed as "combination resonance" and "simultaneous resonance") are revealed and discussed. Specifically, the amplitudes of the combination resonances are quantitatively compared with those of other traditional resonances (e.g. main resonances, harmonics). The influences of several paramount parameters (e.g., the bubble radius, the acoustic pressure amplitude, the energy allocation between two component waves) on nonlinear bubble oscillations are demonstrated.

  8. Probing thermomechanics at the nanoscale: impulsively excited pseudosurface acoustic waves in hypersonic phononic crystals.

    PubMed

    Nardi, Damiano; Travagliati, Marco; Siemens, Mark E; Li, Qing; Murnane, Margaret M; Kapteyn, Henry C; Ferrini, Gabriele; Parmigiani, Fulvio; Banfi, Francesco

    2011-10-12

    High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system's initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system's excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths.

  9. Probing Thermomechanics at the Nanoscale: Impulsively Excited Pseudosurface Acoustic Waves in Hypersonic Phononic Crystals

    PubMed Central

    2011-01-01

    High-frequency surface acoustic waves can be generated by ultrafast laser excitation of nanoscale patterned surfaces. Here we study this phenomenon in the hypersonic frequency limit. By modeling the thermomechanics from first-principles, we calculate the system’s initial heat-driven impulsive response and follow its time evolution. A scheme is introduced to quantitatively access frequencies and lifetimes of the composite system’s excited eigenmodes. A spectral decomposition of the calculated response on the eigemodes of the system reveals asymmetric resonances that result from the coupling between surface and bulk acoustic modes. This finding allows evaluation of impulsively excited pseudosurface acoustic wave frequencies and lifetimes and expands our understanding of the scattering of surface waves in mesoscale metamaterials. The model is successfully benchmarked against time-resolved optical diffraction measurements performed on one-dimensional and two-dimensional surface phononic crystals, probed using light at extreme ultraviolet and near-infrared wavelengths. PMID:21910426

  10. HF Doppler observations of acoustic waves excited by the earthquake

    NASA Technical Reports Server (NTRS)

    Ichinose, T.; Takagi, K.; Tanaka, T.; Okuzawa, T.; Shibata, T.; Sato, Y.; Nagasawa, C.; Ogawa, T.

    1985-01-01

    Ionospheric disturbances caused by the earthquake of a relatively small and large epicentral distance have been detected by a network of HF-Doppler sounders in central Japan and Kyoto station, respectively. The HF-Doppler data of a small epicentral distance, together with the seismic data, have been used to formulate a mechanism whereby ionospheric disturbances are produced by the Urakawa-Oki earthquake in Japan. Comparison of the dynamic spectra of these data has revealed experimentally that the atmosphere acts as a low-pass filter for upward-propagating acoustic waves. By surveying the earthquakes for which the magnitude M is larger than 6.0, researchers found the ionospheric effect in 16 cases of 82 seismic events. As almost all these effects have occurred in the daytime, it is considered that it may result from the filtering effect of the upward-propagating acoustic waves.

  11. Coupling between Hydrodynamics, Acoustics, and Heat Release in a Self-Excited Unstable Combustor

    DTIC Science & Technology

    2015-04-07

    Averaged Navier-Stokes) of a non- premixed, high -pressure laboratory combustor that produces self-excited longitudinal instabilities . The main...acoustic excitation.13 Such hydrodynamic instabilities arising when pressure pulses reflecting from the downstream end of the flow domain lock on to an...spatio- temporal observation of the combustion field. High - speed imagery of the CH* radical showed clear changes in the unsteady combustion field as

  12. A model for the acoustic impedance of a perforated plate liner with multiple frequency excitation

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1971-01-01

    A nonlinear resistance model is used in the one-dimensional equations of motion with an arbitrary exciting pressure function. The effects of high amplitude fluid motion, grazing flow, and spectral excitation can be studied together. Sample calculations of acoustic resistances are presented using a high amplitude discrete tone superimposed upon a simulated white noise spectrum. The tone amplitude is varied and its effect is shown both with and without a grazing flow velocity.

  13. Droplet Combustion and Non-Reactive Shear-Coaxial Jets with Transverse Acoustic Excitation

    DTIC Science & Technology

    2012-06-01

    Excitation of Coaxial Jets The earliest investigations of the effect of ambient pressure oscillations on free jets in- cludes those by Miesse [51], Newman [52...less effective in breaking up the jet than at lower chamber pressure. A majority of the studies done on acoustically excited coaxial jets involve in...outer jet on the near-field dynamics of the inner jet with axial excitation of each jet independently for 0.55 < R < 1.45. Axial forcing of the outer jet

  14. Mobility power flow analysis of coupled plate structure subjected to mechanical and acoustic excitation

    NASA Technical Reports Server (NTRS)

    Cuschieri, J. M.

    1992-01-01

    The mobility power flow approach that was previously applied in the derivation of expressions for the vibrational power flow between coupled plate substructures forming an L configuration and subjected to mechanical loading is generalized. Using the generalized expressions, both point and distributed mechanical loads on one or both of the plates can be considered. The generalized approach is extended to deal with acoustic excitation of one of the plate substructures. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the plate structure and the acoustic fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure. For a number of coupled plate substrates, the acoustic pressure generated by one substructure will interact with the motion of another substructure. That is, in the case of the L-shaped plate, acoustic interaction exists between the two plate substructures due to the generation of the acoustic waves by each of the substructures. An approach to deal with this phenomena is described.

  15. Dust Acoustic Wave Excitation in a Plasma with Warm Dust

    NASA Astrophysics Data System (ADS)

    Rosenberg, M.; Thomas, E., Jr.; Marcus, L.; Fisher, R.; Williams, J. D.; Merlino, R. L.

    2008-11-01

    Measurements of the dust acoustic wave dispersion relation in dusty plasmas formed in glow discharges at the University of Iowa [1] and Auburn University [2] have shown the importance of finite dust temperature effects. The effect of dust grains with large thermal speeds was taken into account using kinetic theory of the ion-dust streaming instability [3]. The results of analytic and numerical calculations of the dispersion relation based on the kinetic theory will be presented and compared with the experimental results. [1] E. Thomas, Jr., R. Fisher, and R. L. Merlino, Phys. Plasmas 14, 123701 (2007). [2] J. D. Williams, E. Thomas Jr., and L. Marcus, Phys. Plasmas 15, 043704 (2008). [3] M. Rosenberg, E. Thomas Jr., and R. L. Merlino, Phys. Plasmas 15, 073701 (2008).

  16. Collective Lipid Bilayer Dynamics Excited by Surface Acoustic Waves

    NASA Astrophysics Data System (ADS)

    Reusch, T.; Schülein, F. J. R.; Nicolas, J. D.; Osterhoff, M.; Beerlink, A.; Krenner, H. J.; Müller, M.; Wixforth, A.; Salditt, T.

    2014-09-01

    We use standing surface acoustic waves to induce coherent phonons in model lipid multilayers deposited on a piezoelectric surface. Probing the structure by phase-controlled stroboscopic x-ray pulses we find that the internal lipid bilayer electron density profile oscillates in response to the externally driven motion of the lipid film. The structural response to the well-controlled motion is a strong indication that bilayer structure and membrane fluctuations are intrinsically coupled, even though these structural changes are averaged out in equilibrium and time integrating measurements. Here the effects are revealed by a timing scheme with temporal resolution on the picosecond scale in combination with the sub-nm spatial resolution, enabled by high brilliance synchrotron x-ray reflectivity.

  17. Flame response to acoustic excitation in a rectangular rocket combustor with LOx/H2 propellants

    NASA Astrophysics Data System (ADS)

    Hardi, Justin; Oschwald, Michael; Dally, Bassam

    2011-12-01

    Research efforts are currently underway at the German Aerospace Center (DLR) Lampoldshausen, which aim to understand the mechanisms by which self-sustaining oscillations in combustion chamber pressure, known as high frequency combustion instabilities, are driven. Testing has been conducted in the rectangular combustor `BKH', running cryogenic oxygen and hydrogen propellants under pressure and injection conditions which are representative of real rocket engines and with acoustic forcing. For the first time, such tests with LOx/H2 propellants and acoustic forcing have been conducted at combustion chamber pressures above 10 bar, the reported results herein from a test at 42 bar. Optical access to the combustor allowed the application of high speed hydroxyl radical (OH*) chemiluminescence imaging of the flame during periods of forced excitation of acoustic resonance modes of the combustion chamber. This paper reports the investigation of flame response to acoustic excitation. Both fluctuation in OH* emission intensity and deflection of the flame at frequencies corresponding to the excitation frequency have been observed. These responses are then discussed as potential indicators of driving mechanisms for combustion instabilities.

  18. Incompressible Modes Excited by Supersonic Shear in Boundary Layers: Acoustic CFS Instability

    NASA Astrophysics Data System (ADS)

    Belyaev, Mikhail A.

    2017-02-01

    We present an instability for exciting incompressible modes (e.g., gravity or Rossby modes) at the surface of a star accreting through a boundary layer. The instability excites a stellar mode by sourcing an acoustic wave in the disk at the boundary layer, which carries a flux of energy and angular momentum with the opposite sign as the energy and angular momentum density of the stellar mode. We call this instability the acoustic Chandrasekhar–Friedman–Schutz (CFS) instability, because of the direct analogy to the CFS instability for exciting modes on a rotating star by emission of energy in the form of gravitational waves. However, the acoustic CFS instability differs from its gravitational wave counterpart in that the fluid medium in which the acoustic wave propagates (i.e., the accretion disk) typically rotates faster than the star in which the incompressible mode is sourced. For this reason, the instability can operate even for a non-rotating star in the presence of an accretion disk. We discuss applications of our results to high-frequency quasi-periodic oscillations in accreting black hole and neutron star systems and dwarf nova oscillations in cataclysmic variables.

  19. Mobility power flow analysis of an L-shaped plate structure subjected to acoustic excitation

    NASA Technical Reports Server (NTRS)

    Cuschieri, J. M.

    1989-01-01

    An analytical investigation based on the Mobility Power Flow method is presented for the determination of the vibrational response and power flow for two coupled flat plate structures in an L-shaped configuration, subjected to acoustical excitation. The principle of the mobility power flow method consists of dividing the global structure into a series of subsystems coupled together using mobility functions. Each separate subsystem is analyzed independently to determine the structural mobility functions for the junction and excitation locations. The mobility functions, together with the characteristics of the junction between the subsystems, are then used to determine the response of the global structure and the power flow. In the coupled plate structure considered here, mobility power flow expressions are derived for excitation by an incident acoustic plane wave. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the structure and the fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure.

  20. Nonlinear acoustics with low-profile piezoceramic excitation for crack detection in metallic structures

    NASA Astrophysics Data System (ADS)

    Parsons, Z.; Staszewski, W. J.

    2006-08-01

    Structural damage detection is one of the major maintenance activities in a wide range of industries. A variety of different methods have been developed for detection of fatigue cracks in metallic structures over the last few decades. This includes techniques based on stress/acoustic waves propagating in monitored structures. Classical ultrasonic techniques used in nondestructive testing and evaluation are based on linear amplitude and/or phase variations of reflected, transmitted or scattered waves. In recent years a range of different techniques utilizing nonlinear phenomena in vibration and acoustic signals have been developed. It appears that these techniques are more sensitive to damage alterations than other techniques used for damage detection based on linear behaviour. The paper explores the use of low-profile piezoceramic actuators with low-frequency excitation in nonlinear acoustics. The method is used to detect a fatigue crack in an aluminium plate. The results are compared with modal/vibration excitation performed with an electromagnetic shaker. The study shows that piezoelectric excitation with surface-bonded low-profile piezoceramic transducers is suitable for crack detection based on nonlinear acoustics.

  1. Acoustic and vibration response of a structure with added noise control treatment under various excitations.

    PubMed

    Rhazi, Dilal; Atalla, Noureddine

    2014-02-01

    The evaluation of the acoustic performance of noise control treatments is of great importance in many engineering applications, e.g., aircraft, automotive, and building acoustics applications. Numerical methods such as finite- and boundary elements allow for the study of complex structures with added noise control treatment. However, these methods are computationally expensive when used for complex structures. At an early stage of the acoustic trim design process, many industries look for simple and easy to use tools that provide sufficient physical insight that can help to formulate design criteria. The paper presents a simple and tractable approach for the acoustic design of noise control treatments. It presents and compares two transfer matrix-based methods to investigate the vibroacoustic behavior of noise control treatments. The first is based on a modal approach, while the second is based on wave-number space decomposition. In addition to the classical rain-on-the-roof and diffuse acoustic field excitations, the paper also addresses turbulent boundary layer and point source (monopole) excitations. Various examples are presented and compared to a finite element calculation to validate the methodology and to confirm its relevance along with its limitations.

  2. Resonant-type MEMS transducers excited by two acoustic emission simulation techniques

    NASA Astrophysics Data System (ADS)

    Ozevin, Didem; Greve, David W.; Oppenheim, Irving J.; Pessiki, Stephen

    2004-07-01

    Acoustic emission testing is a passive nondestructive testing technique used to identify the onset and characteristics of damage through the detection and analysis of transient stress waves. Successful detection and implementation of acoustic emission requires good coupling, high transducer sensitivity and ability to discriminate noise from real signals. We report here detection of simulated acoustic emission signals using a MEMS chip fabricated in the multi-user polysilicon surface micromachining (MUMPs) process. The chip includes 18 different transducers with 10 different resonant frequencies in the range of 100 kHz to 1 MHz. It was excited by two different source simulation techniques; pencil lead break and impact loading. The former simulation was accomplished by breaking 0.5 mm lead on the ceramic package. Four transducer outputs were collected simultaneously using a multi-channel oscilloscope. The impact loading was repeated for five different diameter ball bearings. Traditional acoustic emission waveform analysis methods were applied to both data sets to illustrate the identification of different source mechanisms. In addition, a sliding window Fourier transform was performed to differentiate frequencies in time-frequency-amplitude domain. The arrival and energy contents of each resonant frequency were investigated in time-magnitude plots. The advantages of the simultaneous excitation of resonant transducers on one chip are discussed and compared with broadband acoustic emission transducers.

  3. Resonant excitation of intense acoustic waves in crystals

    SciTech Connect

    Alshits, V. I. Bessonov, D. A.; Lyubimov, V. N.

    2013-06-15

    The resonant excitation of an intense elastic wave through nonspecular reflection of a special pump wave in a crystal is described. The choice of the plane and angle of incidence is dictated by the requirement that the excited reflected wave be close to the bulk eigenmode with its energy flow along a free boundary. The resonance parameters have been found for a medium with an arbitrary anisotropy. General relations are concretized for monoclinic, rhombic, and hexagonal systems. A criterion is formulated for an optimal selection of crystals in which the resonant reflection is close to the conversion one, when almost all of the energy from the incident beam of the pump wave falls into the near-surface narrow high-intensity reflected beam. Estimates and illustrations are given for such crystals as an example. The intensity of the reflected beam increases with its narrowing, but its diffraction divergence also increases with this narrowing. Nevertheless, the intensity of the beam can be increased by a factor of 5-10 at sufficiently high frequencies while keeping its divergence at an acceptable level. Amplification by two orders of magnitude can be achieved by compressing the beam in two dimensions through its double reflection.

  4. Excitation of intense acoustic waves in hexagonal crystals

    SciTech Connect

    Alshits, V. I. Bessonov, D. A.; Lyubimov, V. N.

    2013-11-15

    Resonant excitation of an intense elastic wave using reflection of a pump wave from a free surface of hexagonal crystal is described. A resonance arises in the case of specially chosen propagation geometry where the reflecting boundary slightly deviates from symmetric orientation and the propagation direction of an intense reflected wave is close to that of an exceptional bulk wave, which satisfies the free boundary condition in unperturbed symmetric orientation. It is shown that, in crystals with elastic moduli c{sub 44}>c{sub 66}, a resonance arises when the initial boundary is chosen parallel to the hexagonal axis 6, whereas in crystals characterized by the relation c{sub 44}excited beam depends on the specific relations between the elastic moduli and can be rather significant for specially chosen crystals. Examples of crystals are presented in which the beam intensity can be increased by a factor of 5-10 at sufficiently high frequencies, with beam divergence remaining acceptable.

  5. Specific Plasma Ionospheric Excitations Modes in the Ionosphere Produced by Space Vehicle Launch and RE Entry and Natural Phenomena

    NASA Astrophysics Data System (ADS)

    Rauscher, E. A.; van Bise, W. L.

    2001-10-01

    SPECIFIC PLASMA IONOSPHERIC EXCITATIONS MODES IN THE IONOSPHERE PRODUCED BY SPACE VEHICLE LAUNCH AND RE ENTRY AND NATURAL PHENOMENA We have examined both experimentally and theoretically the formation and excitation of highly well defined specific wave forms of plasma excitation in the D, E, F(1) and F(2) and sometimes G layers of the earth?s ionosphere. In our formal study period from October 1989 until December 1996, we measured 41 distinct events out of a possible 73 events utilizing ground based sensitive T1050 magnetometers. In five cases more than two to three stations were displayed and detected the same ionospheric excitations. Sometimes background noise was high and dominated the signals, but under good measurement conditions signals appeared to be 50 to 70 dbm over the background noise floor. Specific frequencies of the D-layer appeared around 5.2 to 6.52 Hz and E layer excitations were from 10.48 to 12.8 Hz. Sometimes an F double peak appeared around 15 to 17 Hz as excited by space shuttle activity and delta rockets and in several cases, large scale volcanism. A theoretical model has been developed which describes sustained long duration and long range coherent plasma excitation modes which occur when the ionospheric layers are shock excited. Alfven-like velocities of propogation are calculated in these ionospheric layer. Some Schumann resonates were observed from 7 to 8 Hz.

  6. Acoustic Excitation of a Micro-bubble Inside a Rigid Tube

    NASA Astrophysics Data System (ADS)

    Qamar, Adnan; Samtaney, Ravi

    2012-11-01

    A theoretical model for acoustic excitation of a single micro-bubble inside a rigid tube is proposed in the present work. The model is derived from the reduced Navier-Stokes equations and by utilizing Poiseuille pipe flow theory. Wall Frictional losses induced due to fluid motion by the bubble oscillation in response to the acoustic perturbation are taken into account. The proposed model is not a variant of conventional Rayleigh-Plesset (RP) equation and is principally a super-set of all the conventional RP models. The model is first of its kind, which relates the bubble dynamics with the tube geometric and acoustic parameters in a consistent manner. Model predicts bubble oscillation dynamics as well as bubble fragmentation quite well when compared to the available experimental data. Results are computed for three tube diameters of 200, 100 and 12 microns with two initial bubble radiuses of 1.5 and 2 microns. The response of micro-bubble is highly non-linear with the driving acoustic frequency. Bubble response for low acoustic peak negative pressure (PNP) is linear, whereas as the PNP is increase nonlinearity are manifested and eventually bubble fragmentation takes place. For fixed acoustic parameters, an exponential decay in bubble response is observed as the tube length is increased. For very small tube diameters, the predictions are damped, suggesting the breakdown of the inherent model assumptions for these cases.

  7. A model for the pressure excitation spectrum and acoustic impedance of sound absorbers in the presence of grazing flow

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1973-01-01

    The acoustic impedance of sound absorbers in the presence of grazing flow is essential information when analyzing sound propagation within ducts. A unification of the theory of the nonlinear acoustic resistance of Helmholtz resonators including grazing flow is presented. The nonlinear resistance due to grazing flow is considered to be caused by an exciting pressure spectrum produced by the interaction of the grazing flow and the jets flowing from the resonator orifices. With this exciting pressure spectrum the resonator can be treated in the same manner as a resonator without grazing flow but with an exciting acoustic spectrum.

  8. Radial structures and nonlinear excitation of Geodesic Acoustic Modes

    NASA Astrophysics Data System (ADS)

    Chen, Liu; Zonca, Fulvio

    2007-11-01

    In this paper, we show that GAMs constitute a continuous spectrum due to radial inhomogeneities. The existence of singular layer, thus, suggests linear mode conversion to short-wavelength kinetic GAM (KGAM) via finite ion Larmor radii. This result is demonstrated by derivations of the GAM mode structure and dispersion relation in the singular layer. At the lowest order in krρi, with kr the radial wave vector and ρi the ion Larmor radius, the well known kinetic dispersion relation of GAM is recovered. At the next relevant order, O(kr^2ρi^2), we show that KGAM propagates in the low-temperature and/or high safety-factor domain; i.e., typically, radially outward, and a corresponding damping rate is derived. In this work, we also show that, while KGAM is linearly stable due to ion Landau damping, it can be nonlinearly excited by finite-amplitude DW turbulence via 3-wave parametric interactions. The resultant 3-wave system exhibits the typical prey-predator self-regulatory dynamics.

  9. On the mechanism of turbulence suppression in free shear flows under acoustic excitation

    NASA Technical Reports Server (NTRS)

    Zaman, K. B. M. Q.; Rice, E. J.

    1992-01-01

    Acoustic excitation at certain high frequencies has been known to suppress large amplitude fluctuations otherwise occurring naturally in various free shear flows. The phenomenon has been observed in flows with initially laminar or transitional boundary layers. An experimental investigation is conducted to consider two possibilities in regards to the mechanism of the effect. (1) The natural shear layer is self excited by the instability waves already developed in the upstream boundary layer. This is overridden when the shear layer is excited at its maximally unstable mode, causing the observed decrease in the intensities downstream. (2) The upstream boundary layer is in a transitional or buffeted laminar state, characterized by large amplitude unsteady fluctuations, which force the large fluctuations downstream. Excitation trips the upstream boundary layer to full turbulence, reduces the unsteady fluctuations, and thus causes the observed suppression of the intensities throughout the flowfield. The present experimental results refute either of these possibilities to be the general mechanism of the effect.

  10. Capturing molecular multimode relaxation processes in excitable gases based on decomposition of acoustic relaxation spectra

    NASA Astrophysics Data System (ADS)

    Zhu, Ming; Liu, Tingting; Wang, Shu; Zhang, Kesheng

    2017-08-01

    Existing two-frequency reconstructive methods can only capture primary (single) molecular relaxation processes in excitable gases. In this paper, we present a reconstructive method based on the novel decomposition of frequency-dependent acoustic relaxation spectra to capture the entire molecular multimode relaxation process. This decomposition of acoustic relaxation spectra is developed from the frequency-dependent effective specific heat, indicating that a multi-relaxation process is the sum of the interior single-relaxation processes. Based on this decomposition, we can reconstruct the entire multi-relaxation process by capturing the relaxation times and relaxation strengths of N interior single-relaxation processes, using the measurements of acoustic absorption and sound speed at 2N frequencies. Experimental data for the gas mixtures CO2-N2 and CO2-O2 validate our decomposition and reconstruction approach.

  11. Excitation and propagation of shear-horizontal-type surface and bulk acoustic waves.

    PubMed

    Hashimoto, K Y; Yamaguchi, M

    2001-09-01

    This paper reviews the basic properties of shear-horizontal (SH)-type surface acoustic waves (SAWs) and bulk acoustic waves (BAWs). As one of the simplest cases, the structure supporting Bleustein-Gulyaev-Shimizu waves is considered, and their excitation and propagation are discussed from various view points. First, the formalism based on the complex integral theory is presented, where the surface is assumed to be covered with an infinitesimally thin metallic film, and it is shown how the excitation and propagation of SH-type waves are affected by the surface perturbation. Then, the analysis is extended to a periodic grating structure, and the behavior of SH-type SAWs under the grating structure is discussed. Finally, the origin of the leaky nature is explained.

  12. Acoustic and flexural excitation of a floating structure by a single laser pulse.

    PubMed

    Philp, W R; Podlesak, M; Pierce, S G

    1996-12-20

    The acoustic and flexural vibrations of a small-scale floating structure following irradiation by a pulsed Nd:glass laser are compared with a radiated underwater sound field. A single subablative laser pulse of 600-μs duration was used both to bend and shock the floating structure at the irradiation site. The laser pulse caused the structure to flex at a frequency of approximately 1 kHz whereas relaxation oscillations in the laser output simultaneously excited ultrasonic Lamb waves within the material bulk. We present results to illustrate the broad bandwidth provided by this unusual form of excitation.

  13. Flow-excited acoustic resonance of a Helmholtz resonator: Discrete vortex model compared to experiments

    SciTech Connect

    Dai, Xiwen; Jing, Xiaodong Sun, Xiaofeng

    2015-05-15

    The acoustic resonance in a Helmholtz resonator excited by a low Mach number grazing flow is studied theoretically. The nonlinear numerical model is established by coupling the vortical motion at the cavity opening with the cavity acoustic mode through an explicit force balancing relation between the two sides of the opening. The vortical motion is modeled in the potential flow framework, in which the oscillating motion of the thin shear layer is described by an array of convected point vortices, and the unsteady vortex shedding is determined by the Kutta condition. The cavity acoustic mode is obtained from the one-dimensional acoustic propagation model, the time-domain equivalent of which is given by means of a broadband time-domain impedance model. The acoustic resistances due to radiation and viscous loss at the opening are also taken into account. The physical processes of the self-excited oscillations, at both resonance and off-resonance states, are simulated directly in the time domain. Results show that the shear layer exhibits a weak flapping motion at the off-resonance state, whereas it rolls up into large-scale vortex cores when resonances occur. Single and dual-vortex patterns are observed corresponding to the first and second hydrodynamic modes. The simulation also reveals different trajectories of the two vortices across the opening when the first and second hydrodynamic modes co-exist. The strong modulation of the shed vorticity by the acoustic feedback at the resonance state is demonstrated. The model overestimates the pressure pulsation amplitude by a factor 2, which is expected to be due to the turbulence of the flow which is not taken into account. The model neglects vortex shedding at the downstream and side edges of the cavity. This will also result in an overestimation of the pulsation amplitude.

  14. Modal measurements and propeller field excitation on acoustic full scale mockup of SAAB 340 aircraft

    NASA Astrophysics Data System (ADS)

    Gustavsson, Lars

    1992-06-01

    The acoustic mockup of the cabin SAAB 340 aircraft was measured in an anechoic chamber concerning modal parameters and operating deflection shapes. The mockup was excited with vibration shakers at the fuselage for modal estimation and with a ring of loudspeakers around the fuselage to generate propeller fields for operating deflection shapes. Two cases of structure configuration were used at the measurements; one consisting of only the fuselage, without trimpanels and floorpanels and one case with trimpanels and floorpanels. Modal measurements were done with excitation on a frame of the fuselage at the propeller plane. The modes were estimated for the individual components; fuselage, trimpanels, floorpanels, and soundfield in the cabin. The modes of the fuselage were compared with the acoustic models in the cabin concerning possible coupling effects. With the loudspeakering, the sound field from the left and the right propeller were generated at a blade passage frequency of 81.9 Hz and its first harmonic. Operating deflection shapes of fuselage, panels, and cabin acoustic were estimated. The results from the measurements could be used to verify a finite element model and as a tool for developing acoustic noise control systems.

  15. Simulation of jet-noise excitation in an acoustic progressive wave tube facility.

    PubMed

    Steinwolf, A; White, R G; Wolfe, H F

    2001-03-01

    Acoustic excitation produced by jet-engine effluxes was simulated in a progressive wave tube (APWT) facility with a computer-based control system. The APWT siren is driven by a signal generated numerically in a PC and then converted into analog form. Characteristics of the acoustic pressure measured by a microphone are analyzed in digital form and compared with those prescribed for simulation. Divergence is compensated by immediate modification of the driving signal and this action is repeated in the form of iterative process until the test specification is attained. Typical power spectral density (PSD) shapes with maxima at low and high frequencies were simulated. A "tailoring" approach has been also achieved when a test specification was determined directly from field measurements for the particular aircraft under consideration. Since acoustic pressure signals of high level differ from the Gaussian random process model, particularly in terms of asymmetric probability density function, a method has been developed to make the driving signal also non-Gaussian by simulating skewness and kurtosis parameters of the APWT acoustic excitation simultaneously with PSD control. Experimental results with Gaussian and non-Gaussian characteristics obtained for various PSD specifications including sharp and narrow peaks are presented in the paper.

  16. Dust acoustic solitary and shock excitations in a Thomas-Fermi magnetoplasma

    SciTech Connect

    Rahim, Z.; Qamar, A.; Ali, S.

    2014-07-15

    The linear and nonlinear properties of dust-acoustic waves are investigated in a collisionless Thomas-Fermi magnetoplasma, whose constituents are electrons, ions, and negatively charged dust particles. At dust time scale, the electron and ion number densities follow the Thomas-Fermi distribution, whereas the dust component is described by the classical fluid equations. A linear dispersion relation is analyzed to show that the wave frequencies associated with the upper and lower modes are enhanced with the variation of dust concentration. The effect of the latter is seen more strongly on the upper mode as compared to the lower mode. For nonlinear analysis, we obtain magnetized Korteweg-de Vries (KdV) and Zakharov-Kuznetsov (ZK) equations involving the dust-acoustic solitary waves in the framework of reductive perturbation technique. Furthermore, the shock wave excitations are also studied by allowing dissipation effects in the model, leading to the Korteweg-de Vries-Burgers (KdVB) and ZKB equations. The analysis reveals that the dust-acoustic solitary and shock excitations in a Thomas-Fermi plasma are strongly influenced by the plasma parameters, e.g., dust concentration, dust temperature, obliqueness, magnetic field strength, and dust fluid viscosity. The present results should be important for understanding the solitary and shock excitations in the environments of white dwarfs or supernova, where dust particles can exist.

  17. Identification of vibration excitations from acoustic measurements using near field acoustic holography and the force analysis technique

    NASA Astrophysics Data System (ADS)

    Pézerat, C.; Leclère, Q.; Totaro, N.; Pachebat, M.

    2009-10-01

    This study presents a method of using acoustic holography and the force analysis technique to identify vibration sources from radiated noise measurements. The structure studied is a plate excited by a shaker on which three measurements were performed: the first is a reference measurement of plate velocity obtained by scanning laser vibrometry, the second is based on sound pressure measurements in the near field of the structure, and the third is the measurement of normal acoustic velocities by using a p-U probe recently developed by Microflown Technologies. This was followed by the application of classical NAH, known as pressure-to-velocity holography and velocity-to-velocity holography to predict the plate velocity field from acoustic measurements at distances of 1 and 5 cm. Afterwards, the force analysis technique, also known as the RIFF technique, is applied with these five data sets. The principle is to inject the displacement field of the structure into its equation of motion and extract the resulting force distribution. This technique requires regularization done by a low-pass filter in the wavenumber domain. Apart from pressure-to-velocity holography at 5 cm, the reconstructed force distribution allows localizing the excitation point in the measurement area. FAT regularization is also shown to improve results as its cutoff wavenumber is optimized with the natural wavenumber of the plate. Lastly, quantitative force values are extracted from force distributions at all frequencies of the band 0-4 kHz studied and compared with the force spectrum measured directly by a piezoelectric sensor.

  18. Validation and Simulation of Ares I Scale Model Acoustic Test - 2 - Simulations at 5 Foot Elevation for Evaluation of Launch Mount Effects

    NASA Technical Reports Server (NTRS)

    Strutzenberg, Louise L.; Putman, Gabriel C.

    2011-01-01

    The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. Expanding from initial simulations of the ASMAT setup in a held down configuration, simulations have been performed using the Loci/CHEM computational fluid dynamics software for ASMAT tests of the vehicle at 5 ft. elevation (100 ft. real vehicle elevation) with worst case drift in the direction of the launch tower. These tests have been performed without water suppression and have compared the acoustic emissions for launch structures with and without launch mounts. In addition, simulation results have also been compared to acoustic and imagery data collected from similar live-fire tests to assess the accuracy of the simulations. Simulations have shown a marked change in the pattern of emissions after removal of the launch mount with a reduction in the overall acoustic environment experienced by the vehicle and the formation of highly directed acoustic waves moving across the platform deck. Comparisons of simulation results to live-fire test data showed good amplitude and temporal correlation and imagery comparisons over the visible and infrared wavelengths showed qualitative capture of all plume and pressure wave evolution features.

  19. Vibro-Acoustic Forecast for Space Shuttle Launches at Vandenberg AFB: The Payload Changeout Room and the Administration Building,

    DTIC Science & Technology

    2014-09-26

    7 RD-0156 944 VIBRO-RCOUS’IC FORECAST FOR SPACE SHUTTLE LAUNCHES AT / VANDENBERG AFB: THE..( U ) WESTON OB ERVATORY MR F A CROWLEY ET AL. 31 OCT 84...altitude of 300 meters. At thi v t ir the enuivatent acoustic source is 100 meters below the Shuttle WI. Thie ,’ASP1E ma xir: is 1R4.5 Wb (151 b for . S ...is constrained to use only the first 1𔃺 meters of Shuttle traject ory. As the Shuttle moves south, backscatter OtI the PPR south wall .haould nearly

  20. Excitation of monochromatic and stable electron acoustic wave by two counter-propagating laser beams

    NASA Astrophysics Data System (ADS)

    Xiao, C. Z.; Liu, Z. J.; Zheng, C. Y.; He, X. T.

    2017-07-01

    The undamped electron acoustic wave is a newly-observed nonlinear electrostatic plasma wave and has potential applications in ion acceleration, laser amplification and diagnostics due to its unique frequency range. We propose to make the first attempt to excite a monochromatic and stable electron acoustic wave (EAW) by two counter-propagating laser beams. The matching conditions relevant to laser frequencies, plasma density, and electron thermal velocity are derived and the harmonic effects of the EAW are excluded. Single-beam instabilities, including stimulated Raman scattering and stimulated Brillouin scattering, on the excitation process are quantified by an interaction quantity, η =γ {τ }B, where γ is the growth rate of each instability and {τ }B is the characteristic time of the undamped EAW. The smaller the interaction quantity, the more successfully the monochromatic and stable EAW can be excited. Using one-dimensional Vlasov-Maxwell simulations, we excite EAW wave trains which are amplitude tunable, have a duration of thousands of laser periods, and are monochromatic and stable, by carefully controlling the parameters under the above conditions.

  1. On the slow dynamics of near-field acoustically levitated objects under High excitation frequencies

    NASA Astrophysics Data System (ADS)

    Ilssar, Dotan; Bucher, Izhak

    2015-10-01

    This paper introduces a simplified analytical model describing the governing dynamics of near-field acoustically levitated objects. The simplification converts the equation of motion coupled with the partial differential equation of a compressible fluid, into a compact, second order ordinary differential equation, where the local stiffness and damping are transparent. The simplified model allows one to more easily analyse and design near-field acoustic levitation based systems, and it also helps to devise closed-loop controller algorithms for such systems. Near-field acoustic levitation employs fast ultrasonic vibrations of a driving surface and exploits the viscosity and the compressibility of a gaseous medium to achieve average, load carrying pressure. It is demonstrated that the slow dynamics dominates the transient behaviour, while the time-scale associated with the fast, ultrasonic excitation has a small presence in the oscillations of the levitated object. Indeed, the present paper formulates the slow dynamics under an ultrasonic excitation without the need to explicitly consider the latter. The simplified model is compared with a numerical scheme based on Reynolds equation and with experiments, both showing reasonably good results.

  2. Anomalous properties of the acoustic excitations in glasses on the mesoscopic length scale

    PubMed Central

    Monaco, Giulio; Mossa, Stefano

    2009-01-01

    The low-temperature thermal properties of dielectric crystals are governed by acoustic excitations with large wavelengths that are well described by plane waves. This is the Debye model, which rests on the assumption that the medium is an elastic continuum, holds true for acoustic wavelengths large on the microscopic scale fixed by the interatomic spacing, and gradually breaks down on approaching it. Glasses are characterized as well by universal low-temperature thermal properties that are, however, anomalous with respect to those of the corresponding crystalline phases. Related universal anomalies also appear in the low-frequency vibrational density of states and, despite a longstanding debate, remain poorly understood. By using molecular dynamics simulations of a model monatomic glass of extremely large size, we show that in glasses the structural disorder undermines the Debye model in a subtle way: The elastic continuum approximation for the acoustic excitations breaks down abruptly on the mesoscopic, medium-range-order length scale of ≈10 interatomic spacings, where it still works well for the corresponding crystalline systems. On this scale, the sound velocity shows a marked reduction with respect to the macroscopic value. This reduction turns out to be closely related to the universal excess over the Debye model prediction found in glasses at frequencies of ≈1 THz in the vibrational density of states or at temperatures of ≈10 K in the specific heat. PMID:19805115

  3. Response of a swirl-stabilized flame to transverse acoustic excitation

    NASA Astrophysics Data System (ADS)

    O'Connor, Jacqueline

    This work addresses the issue of transverse combustion instabilities in annular gas turbine combustor geometries. While modern low-emissions combustion strategies have made great strides in reducing the production of toxic emissions in aircraft engines and power generation gas turbines, combustion instability remains one of the foremost technical challenges in the development of next generation combustor technology. To that end, this work investigates the response of a swirling flow and swirl-stabilized flame to a transverse acoustic field is using a variety of high-speed laser techniques, especially high-speed particle image velocimetry (PIV) for detailed velocity measurements of this highly unsteady flow phenomenon. Several important issues are addressed. First, the velocity-coupled pathway by which the unsteady velocity field excites the flame is described in great detail. Here, a transfer function approach has been taken to illustrate the various pathways through which the flame is excited by both acoustic and vortical velocity fluctuations. It has been shown that while the direct excitation of the flame by the transverse acoustic field is a negligible effect in most combustor architectures, the coupling between the transverse acoustic mode in the combustor and the longitudinal mode in the nozzle is an important pathway that can result in significant flame response. In this work, the frequency response of this pathway as well as the resulting flame response is measured using PIV and chemiluminescence measurements, respectively. Next, coupling between the acoustic field and the hydrodynamically unstable swirling flow provides a pathway that can lead to significant flame wrinkling by large coherent structures in the flow. Swirling flows display two types of hydrodynamic instability: an absolutely unstable jet and convectively unstable shear layers. The absolute instability of the jet results in vortex breakdown, a large recirculation zone along the centerline of

  4. Nonlinear Response of Composite Panels Under Combined Acoustic Excitation and Aerodynamic Pressure

    NASA Technical Reports Server (NTRS)

    Abdel-Motagaly, K.; Duan, B.; Mei, C.

    1999-01-01

    A finite element formulation is presented for the analysis of large deflection response of composite panels subjected to aerodynamic pressure- at supersonic flow and high acoustic excitation. The first-order shear deformation theory is considered for laminated composite plates, and the von Karman nonlinear strain-displacement relations are employed for the analysis of large deflection panel response. The first-order piston theory aerodynamics and the simulated Gaussian white noise are employed for the aerodynamic and acoustic loads, respectively. The nonlinear equations of motion for an arbitrarily laminated composite panel subjected to a combined aerodynamic and acoustic pressures are formulated first in structure node degrees-of-freedom. The system equations are then transformed and reduced to a set of coupled nonlinear equations in modal coordinates. Modal participation is defined and the in-vacuo modes to be retained in the analysis are based on the modal participation values. Numerical results include root mean square values of maximum deflections, deflection and strain response time histories, probability distributions, and power spectrum densities. Results showed that combined acoustic and aerodynamic loads have to be considered for panel analysis and design at high dynamic pressure values.

  5. Target spectrum matrix definition for multiple-input- multiple-output control strategies applied on direct-field- acoustic-excitation tests

    NASA Astrophysics Data System (ADS)

    Alvarez Blanco, M.; Janssens, K.; Bianciardi, F.

    2016-09-01

    During the last two decades there have been several improvements on environmental acoustic qualification testing for launch and space vehicles. Direct field excitation (DFAX) tests using Multiple-Input-Multiple-Output (MIMO) control strategies seems to become the most cost-efficient way for component and subsystem acoustic testing. However there are still some concerns about the uniformity and diffusivity of the acoustic field produced by direct field testing. Lately, much of the documented progresses aimed to solve the non-uniformity of the field by altering the sound pressure level requirement, limiting responses and adding or modifying control microphones positions. However, the first two solutions imply modifying the qualification criteria, which could lead to under-testing, potentially risking the mission. Furthermore, adding or moving control microphones prematurely changes the system configuration, even if it is an optimal geometric layout in terms of wave interference patterns control. This research investigates the target definition as an initial condition for the acoustic MIMO control. Through experiments it is shown that for a given system configuration the performance of a DFAX test strongly depends on the target definition procedure. As output of this research a set of descriptors are presented describing a phenomenon defined as “Energy- sink”.

  6. Observation of subcritical geodesic acoustic mode excitation in the large helical device

    NASA Astrophysics Data System (ADS)

    Ido, T.; Itoh, K.; Lesur, M.; Osakabe, M.; Shimizu, A.; Ogawa, K.; Nishiura, M.; Yamada, I.; Yasuhara, R.; Kosuga, Y.; Sasaki, M.; Ida, K.; Inagaki, S.; Itoh, S.-I.; the LHD Experiment Group

    2017-07-01

    The abrupt and strong excitation of the geodesic acoustic mode (GAM) has been found in the large helical device (LHD), when the frequency of a chirping energetic particle-driven GAM (EGAM) approaches twice that of the GAM frequency. The temporal evolution of the phase relation between the abrupt GAM and the chirping EGAM is common in all events. The result indicates a coupling between the GAM and the EGAM. In addition, the nonlinear evolution of the growth rate of the GAM is observed, and there is a threshold in the amplitude of the GAM for the appearance of nonlinear behavior. A threshold in the amplitude of the EGAM for the abrupt excitation of the GAM is also observed. According to one theory (Lesur et al 2016 Phys. Rev. Lett. 116 015003, Itoh et al 2016 Plasma Phys. Rep. 42 418) the observed abrupt phenomenon can be interpreted as the excitation of the subcritical instability of the GAM. The excitation of a subcritical instability requires a trigger and a seed with sufficient amplitude. The observed threshold in the amplitude of the GAM seems to correspond with the threshold in the seed, and the threshold in the amplitude of the EGAM seems to correspond with the threshold in the magnitude of the trigger. Thus, the observed threshold supports the interpretation that the abrupt phenomenon is the excitation of a subcritical instability of the GAM.

  7. Piezoelectric Shunt Vibration Damping of F-15 Panel under High Acoustic Excitation

    NASA Technical Reports Server (NTRS)

    Wu, Shu-Yau; Turner, Travis L.; Rizzi, Stephen A.

    2000-01-01

    At last year's SPIE symposium, we reported results of an experiment on structural vibration damping of an F-15 underbelly panel using piezoelectric shunting with five bonded PZT transducers. The panel vibration was induced with an acoustic speaker at an overall sound pressure level (OASPL) of about 90 dB. Amplitude reductions of 13.45 and 10.72 dB were achieved for the first and second modes, respectively, using single- and multiple-mode shunting. It is the purpose of this investigation to extend the passive piezoelectric shunt-damping technique to control structural vibration induced at higher acoustic excitation levels, and to examine the controllability and survivability of the bonded PZT transducers at these high levels. The shunting experiment was performed with the Thermal Acoustic Fatigue Apparatus (TAFA) at the NASA Langley Research Center using the same F-15 underbelly panel. The TAFA is a progressive wave tube facility. The panel was mounted in one wall of the TAFA test section using a specially designed mounting fixture such that the panel was subjected to grazing-incidence acoustic excitation. Five PZT transducers were used with two shunt circuits designed to control the first and second modes of the structure between 200 and 400 Hz. We first determined the values of the shunt inductance and resistance at an OASPL of 130 dB. These values were maintained while we gradually increased the OASPL from 130 to 154 dB in 6-dB steps. During each increment, the frequency response function between accelerometers on the panel and the acoustic excitation measured by microphones, before and after shunting, were recorded. Good response reduction was observed up to the 148dB level. The experiment was stopped at 154 dB due to wire breakage from vibration at a transducer wire joint. The PZT transducers, however, were still bonded well on the panel and survived at this high dB level. We also observed shifting of the frequency peaks toward lower frequency when the OASPL

  8. Lagrangian-Eulerian micromotion and wave heating in nonlinear self-excited dust-acoustic waves.

    PubMed

    Liao, Chen-Ting; Teng, Lee-Wen; Tsai, Chen-Yu; Io, Chong-Wai; I, Lin

    2008-05-09

    We investigate particle-wave microdynamics in the large amplitude self-excited dust acoustic wave at the discrete level through direct visualization. The wave field induces dust oscillations which in turn sustain wave propagation. In the regular wave with increasing wave amplitude, dust-wave interaction with uncertain temporary crest trapping and dust-dust interaction lead to the transition from cyclic to disordered dust motion associated with the liquid to the gas transition, and anisotropic non-Gaussian heating. In the irregular wave, particle trough-trapping is also observed, and the heating is nearly Gaussian and less anisotropic.

  9. Observation of self-excited dust acoustic wave in dusty plasma with nanometer size dust grains

    NASA Astrophysics Data System (ADS)

    Deka, Tonuj; Boruah, A.; Sharma, S. K.; Bailung, H.

    2017-09-01

    Dusty plasma with a nanometer size dust grain is produced by externally injecting carbon nanopowder into a radio frequency discharge argon plasma. A self-excited dust acoustic wave with a characteristic frequency of ˜100 Hz is observed in the dust cloud. The average dust charge is estimated from the Orbital Motion Limited theory using experimentally measured parameters. The measured wave parameters are used to determine dusty plasma parameters such as dust density and average inter particle distance. The screening parameter and the coupling strength of the dusty plasma indicate that the system is very close to the strongly coupled state.

  10. Particle-Wave Micro-Dynamics in Nonlinear Self-Excited Dust Acoustic Waves

    SciTech Connect

    Tsai, C.-Y.; Teng, L.-W.; Liao, C.-T.; I Lin

    2008-09-07

    The large amplitude dust acoustic wave can be self-excited in a low-pressure dusty plasma. In the wave, the nonlinear wave-particle interaction determines particle motion, which in turn determines the waveform and wave propagation. In this work, the above behaviors are investigated by directly tracking particle motion through video-microscopy. A Lagrangian picture for the wave dynamics is constructed. The wave particle interaction associated with the transition from ordered to disordered particle oscillation, the wave crest trapping and wave heating are demonstrated and discussed.

  11. Droplet Combustion and Non-Reactive Shear-Coaxial Jets with and without Transverse Acoustic Excitation

    DTIC Science & Technology

    2012-01-01

    et al. [34], Perrault-Joncas and Maslowe [49]). Sevilla et al. [34] investigate the effect of outer to inner jet diameter ratio as well as S on the...Jets with and without Transverse Acoustic Excitation 5a. CONTRACT NUMBER In-House 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR( S ) 5d...PROJECT NUMBER Sophonias Teshome 5e. TASK NUMBER 5f. WORK UNIT NUMBER 23080533 7. PERFORMING ORGANIZATION NAME( S ) AND ADDRESS(ES) 8. PERFORMING

  12. Acoustic excitation of the circular Bragg{endash}Fresnel lens in backscattering geometry

    SciTech Connect

    Souvorov, A.; Snigireva, I.; Snigirev, A.; Aristova, E.; Hartman, Y.

    1997-02-01

    An increment of the x-ray flux in crystal Bragg{endash}Fresnel lens (BFL) focus in backscattering geometry obtained by means of acoustic excitation of the BFL crystal substrate has been investigated. The dependence of the x ray{close_quote}s total reflected power versus ultrasound parameters has been studied in a low frequency range (10{endash}50 MHz). The proposed technique allows an increase in the flux in a BFL focus by a factor of 2 which almost achieves the kinematic limit. {copyright} {ital 1997 American Institute of Physics.}

  13. Digital servo control of random sound test excitation. [in reverberant acoustic chamber

    NASA Technical Reports Server (NTRS)

    Nakich, R. B. (Inventor)

    1974-01-01

    A digital servocontrol system for random noise excitation of a test object in a reverberant acoustic chamber employs a plurality of sensors spaced in the sound field to produce signals in separate channels which are decorrelated and averaged. The average signal is divided into a plurality of adjacent frequency bands cyclically sampled by a time division multiplex system, converted into digital form, and compared to a predetermined spectrum value stored in digital form. The results of the comparisons are used to control a time-shared up-down counter to develop gain control signals for the respective frequency bands in the spectrum of random sound energy picked up by the microphones.

  14. Nonlinear and snap-through responses of curved panels to intense acoustic excitation

    NASA Technical Reports Server (NTRS)

    Ng, C. F.

    1989-01-01

    Assuming a single-mode transverse displacement, a simple formula is derived for the transverse load-displacement relationship of a plate under in-plane compression. The formula is used to derive a simple analytical expression for the nonlinear dynamic response of postbuckled plates under sinusoidal or random excitation. The highly nonlinear motion of snap-through can be easily interpreted using the single-mode formula. Experimental results are obtained with buckled and cylindrical aluminum panels using discrete frequency and broadband excitation of mechanical and acoustic forces. Some important effects of the snap-through motion on the dynamic response of the postbuckled plates are described. Static tests were used to identify the deformation shape during snap-through.

  15. Multiple-mode large deflection random response of beams with nonlinear damping subjected to acoustic excitation

    NASA Technical Reports Server (NTRS)

    Prasad, C. B.; Mei, Chuh

    1987-01-01

    Multiple-mode nonlinear analysis is carried out for beams subjected to acoustic excitation. Effects of both nonlinear damping and large-deflection are included in the analysis in an attempt to explain the experimental phenomena of aircraft panels excited at high sound pressure levels; that is the broadening of the strain response peaks and the increase of modal frequency. An amplitude dependent nonlinear damping model is used in the anlaysis to study the effects and interactions of multiple modes, nonlinear stiffness and nonlinear damping on the random response of beams. Mean square maximum deflection, mean square maximum strain, and spectral density function of maximum strain for simple supported and clamped beams are obtained. It is shown analytically that nonlinear damping contributes significantly to the broadening of the response peak and to the mean square deflection and strain.

  16. Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma.

    PubMed

    Behery, E E; Haas, F; Kourakis, I

    2016-02-01

    The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included.

  17. Weakly nonlinear ion-acoustic excitations in a relativistic model for dense quantum plasma

    NASA Astrophysics Data System (ADS)

    Behery, E. E.; Haas, F.; Kourakis, I.

    2016-02-01

    The dynamics of linear and nonlinear ionic-scale electrostatic excitations propagating in a magnetized relativistic quantum plasma is studied. A quantum-hydrodynamic model is adopted and degenerate statistics for the electrons is taken into account. The dispersion properties of linear ion acoustic waves are examined in detail. A modified characteristic charge screening length and "sound speed" are introduced, for relativistic quantum plasmas. By employing the reductive perturbation technique, a Zakharov-Kuznetzov-type equation is derived. Using the small-k expansion method, the stability profile of weakly nonlinear slightly supersonic electrostatic pulses is also discussed. The effect of electron degeneracy on the basic characteristics of electrostatic excitations is investigated. The entire analysis is valid in a three-dimensional as well as in two-dimensional geometry. A brief discussion of possible applications in laboratory and space plasmas is included.

  18. Picosecond x-ray strain rosette reveals direct laser excitation of coherent transverse acoustic phonons

    SciTech Connect

    Lee, Sooheyong; Williams, G. Jackson; Campana, Maria I.; Walko, Donald A.; Landahl, Eric C.

    2016-01-11

    Using a strain-rosette, we demonstrate the existence of transverse strain using time-resolved x-ray diffraction from multiple Bragg reflections in laser-excited bulk gallium arsenide. We find that anisotropic strain is responsible for a considerable fraction of the total lattice motion at early times before thermal equilibrium is achieved. Our measurements are described by a new model where the Poisson ratio drives transverse motion, resulting in the creation of shear waves without the need for an indirect process such as mode conversion at an interface. Finally, using the same excitation geometry with the narrow-gap semiconductor indium antimonide, we detected coherent transverse acoustic oscillations at frequencies of several GHz.

  19. Picosecond x-ray strain rosette reveals direct laser excitation of coherent transverse acoustic phonons.

    PubMed

    Lee, Sooheyong; Williams, G Jackson; Campana, Maria I; Walko, Donald A; Landahl, Eric C

    2016-01-11

    Using a strain-rosette, we demonstrate the existence of transverse strain using time-resolved x-ray diffraction from multiple Bragg reflections in laser-excited bulk gallium arsenide. We find that anisotropic strain is responsible for a considerable fraction of the total lattice motion at early times before thermal equilibrium is achieved. Our measurements are described by a new model where the Poisson ratio drives transverse motion, resulting in the creation of shear waves without the need for an indirect process such as mode conversion at an interface. Using the same excitation geometry with the narrow-gap semiconductor indium antimonide, we detected coherent transverse acoustic oscillations at frequencies of several GHz.

  20. Picosecond x-ray strain rosette reveals direct laser excitation of coherent transverse acoustic phonons

    PubMed Central

    Lee, Sooheyong; Williams, G. Jackson; Campana, Maria I.; Walko, Donald A.; Landahl, Eric C.

    2016-01-01

    Using a strain-rosette, we demonstrate the existence of transverse strain using time-resolved x-ray diffraction from multiple Bragg reflections in laser-excited bulk gallium arsenide. We find that anisotropic strain is responsible for a considerable fraction of the total lattice motion at early times before thermal equilibrium is achieved. Our measurements are described by a new model where the Poisson ratio drives transverse motion, resulting in the creation of shear waves without the need for an indirect process such as mode conversion at an interface. Using the same excitation geometry with the narrow-gap semiconductor indium antimonide, we detected coherent transverse acoustic oscillations at frequencies of several GHz. PMID:26751616

  1. Vibroacoustic Response of Pad Structures to Space Shuttle Launch Acoustic Loads

    NASA Technical Reports Server (NTRS)

    Margasahayam, R. N.; Caimi, Raoul E.

    1995-01-01

    This paper presents a deterministic theory for the random vibration problem for predicting the response of structures in the low-frequency range (0 to 20 hertz) of launch transients. Also presented are some innovative ways to characterize noise and highlights of ongoing test-analysis correlation efforts titled the Verification Test Article (VETA) project.

  2. Noncontact excitation of guided waves (A0 mode) using an electromagnetic acoustic transducer (EMAT)

    NASA Astrophysics Data System (ADS)

    Fromme, Paul

    2016-02-01

    Fatigue damage can develop in aircraft structures at locations of stress concentration, such as fasteners, and has to be detected before reaching a critical size to ensure safe aircraft operation. Guided ultrasonic waves offer an efficient method for the detection and characterization of such defects in large aerospace structures. Electromagnetic acoustic transducers (EMAT) for the noncontact excitation of guided ultrasonic waves were developed. The transducer development for the specific excitation of the A0 Lamb wave mode with an out-of-plane Lorentz force is explained. The achieved radial and angular dependency of the excited guided wave pulses were measured using a noncontact laser interferometer. Based on the induced eddy currents in the plate a theoretical model was developed. The application of the developed transducers for defect detection in aluminum components using fully noncontact guided wave measurements was demonstrated. Excitation of the A0 Lamb wave mode was achieved using the developed EMAT transducer and the guided wave propagation and scattering was measured using a noncontact laser interferometer.

  3. Development of an electromagnetic acoustic transducer (EMAT) for the noncontact excitation of guided ultrasonic waves

    NASA Astrophysics Data System (ADS)

    Fromme, P.

    2015-03-01

    Fatigue damage can develop in aerospace structures at locations of stress concentration, such as fasteners. For the safe operation of the aircraft fatigue cracks need to be detected before reaching a critical length. Guided ultrasonic waves offer an efficient method for the detection and characterization of such defects in large aerospace structures. Noncontact excitation of guided waves was achieved using electromagnetic acoustic transducers (EMAT). The transducer development for the specific excitation of the A0 Lamb wave mode is explained. The radial and angular dependency of the excited guided wave pulses at different frequencies were measured using a noncontact laser interferometer. Based on the induced eddy currents in the plate a theoretical model was developed and reasonably good agreement with the measured transducer performance was achieved. The developed transducers were employed for defect detection in aluminum components using fully noncontact guided wave measurements. Excitation of the A0 Lamb wave mode was achieved using the developed EMAT transducer and the guided wave propagation and scattering was measured using a noncontact laser interferometer. These results provide the basis for the defect characterization in aerospace structures using noncontact guided wave sensors.

  4. Acoustic excitations in glassy sorbitol and their relation with the fragility and the boson peak

    NASA Astrophysics Data System (ADS)

    Ruta, B.; Baldi, G.; Scarponi, F.; Fioretto, D.; Giordano, V. M.; Monaco, G.

    2012-12-01

    We report a detailed analysis of the dynamic structure factor of glassy sorbitol by using inelastic X-ray scattering and previously measured light scattering data [B. Ruta, G. Monaco, F. Scarponi, and D. Fioretto, Philos. Mag. 88, 3939 (2008), 10.1080/14786430802317586]. The thus obtained knowledge on the density-density fluctuations at both the mesoscopic and macroscopic length scale has been used to address two debated topics concerning the vibrational properties of glasses. The relation between the acoustic modes and the universal boson peak (BP) appearing in the vibrational density of states of glasses has been investigated, also in relation with some recent theoretical models. Moreover, the connection between the elastic properties of glasses and the slowing down of the structural relaxation process in supercooled liquids has been scrutinized. For what concerns the first issue, it is here shown that the wave vector dependence of the acoustic excitations can be used, in sorbitol, to quantitatively reproduce the shape of the boson peak, supporting the relation between BP and acoustic modes. For what concerns the second issue, a proper study of elasticity over a wide spatial range is shown to be fundamental in order to investigate the relation between elastic properties and the slowing down of the dynamics in the corresponding supercooled liquid phase.

  5. Investigation intensity response of distributed-feedback fiber laser to external acoustic excitation Investigation intensity response of DFB fiber laser

    NASA Astrophysics Data System (ADS)

    Wang, P. P.; Chang, J.; Zhu, C. G.; Wang, W. J.; Zhao, Y. J.; Zhang, X. L.; Peng, G. D.; Lv, G. P.; Liu, X. Z.; Wang, H.

    2012-08-01

    The intensity response of distributed-feedback (DFB) fiber laser to external acoustic excitation has been investigated. On that basis, an intensity modulated sensing system based on DFB fiber laser has been constructed. Acoustic pressure sensitivity of the intensity-type sensor at frequencies ranging from 800 Hz to 9 kHz has been obtained by experiments for the first time to the authors' knowledge. In addition, intensity response property of DFB fiber laser to external acoustic excitation with different pump power has been analyzed. We conclude that the signal power increases with the pump drive current of 980 nm laser diode (LD), and yet the ratios of signal power to DFB fiber laser power decrease. It confirms that the anti-interference performance of DFB fiber laser to fixed external acoustic interference becomes stronger with the increasing current of pump source, and this conclusion is beneficial to the investigation of wavelength demodulated sensors.

  6. Heat release and flame structure measurements of self-excited acoustically-driven premixed methane flames

    SciTech Connect

    Kopp-Vaughan, Kristin M.; Tuttle, Steven G.; Renfro, Michael W.; King, Galen B.

    2009-10-15

    An open-open organ pipe burner (Rijke tube) with a bluff-body ring was used to create a self-excited, acoustically-driven, premixed methane-air conical flame, with equivalence ratios ranging from 0.85 to 1.05. The feed tube velocities corresponded to Re = 1780-4450. Coupled oscillations in pressure, velocity, and heat release from the flame are naturally encouraged at resonant frequencies in the Rijke tube combustor. This coupling creates sustainable self-excited oscillations in flame front area and shape. The period of the oscillations occur at the resonant frequency of the combustion chamber when the flame is placed {proportional_to}1/4 of the distance from the bottom of the tube. In this investigation, the shape of these acoustically-driven flames is measured by employing both OH planar laser-induced fluorescence (PLIF) and chemiluminescence imaging and the images are correlated to simultaneously measured pressure in the combustor. Past research on acoustically perturbed flames has focused on qualitative flame area and heat release relationships under imposed velocity perturbations at imposed frequencies. This study reports quantitative empirical fits with respect to pressure or phase angle in a self-generated pressure oscillation. The OH-PLIF images were single temporal shots and the chemiluminescence images were phase averaged on chip, such that 15 exposures were used to create one image. Thus, both measurements were time resolved during the flame oscillation. Phase-resolved area and heat release variations throughout the pressure oscillation were computed. A relation between flame area and the phase angle before the pressure maximum was derived for all flames in order to quantitatively show that the Rayleigh criterion was satisfied in the combustor. Qualitative trends in oscillating flame area were found with respect to feed tube flow rates. A logarithmic relation was found between the RMS pressure and both the normalized average area and heat release rate

  7. Acoustic tests on a new motor generator system for the Minuteman launch control centers at Alpha 01 and Sierra 00, Malmstrom AFB, Montana

    NASA Astrophysics Data System (ADS)

    Fairman, Terry M.

    1991-05-01

    Field tests of the acoustic performance of a new motor generator system (MGS) were performed at Minuteman Launch Control Centers (LCC) Alpha 01 and Sierra 00, Malmstrom AFB, MT. This same MGS unit was accepted for use after the Hill Engineering Test Facilities (HETF) acoustic performance studies conducted in 1988. Rivet Mile from the Ogden ALC began installation of the new MGS at Malmstrom in the spring of 1990. Performance tests were requested by 00-ALC/MMGRMM, and SAC, to compare with the HETF data and document the LCC acoustic environment with the new MGS operating in a field setting. This report presents our findings.

  8. Comment on "Transient response of an acoustic medium by an excited submerged spherical shell" [J. Acoust. Soc. Am. 109(6), 2789-2796 (2001)].

    PubMed

    Bahari, Ako; Popplewell, Neil

    2015-05-01

    A closed form solution was derived previously for the response of a submerged spherical shell when the shell was excited by a spatially distributed, transient load at its inner surface [Zakout (2001). J. Acoust. Soc. Am. 109(6), 2789-2796]. Numerical results were presented for the modal and total acoustic pressures outside the empty sphere when the load's temporal history corresponded to the Heaviside step function. However, the result presented for the shell's "breathing" mode was inconsistent with these data as it corresponded to the delta Dirac (impulse) function. Furthermore, numerical results, which were given later for the total acoustic pressure responses, did not involve either of these excitations. Consequently the present objective is to rectify these anomalies.

  9. A model for the pressure excitation spectrum and acoustic impedance of sound absorbers in the presence of grazing flow.

    NASA Technical Reports Server (NTRS)

    Rice, E. J.

    1973-01-01

    A unification of the theory of the nonlinear acoustic resistance of Helmholtz resonators including grazing flow is presented. The nonlinear resistance due to grazing flow is considered to be caused by an exciting pressure spectrum produced by the interaction of the grazing flow and the jets flowing from the resonator orifices. With this exciting pressure spectrum the resonator can be treated in the same manner as a resonator without grazing flow but with an exciting acoustic spectrum. One of the important implications of this model is that a multiple-degree-of-freedom resonator can be analyzed with grazing flow. Using the grazing flow pressure spectrum, the nonlinear acoustic resistance can be properly distributed among the several elements of the resonator.

  10. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to sensitive spacecraft. This paper employees the Multilevel Fast Multipole Method (MLFMM) feature of a commercial electromagnetic tool to model the fairing electromagnetic environment in the presence of an internal transmitter. This work is an extension of the perfect electric conductor model that was used to represent the bare aluminum internal fairing cavity. This fairing model includes typical acoustic blanketing commonly used in vehicle fairings. Representative material models within FEKO were successfully used to simulate the test case.

  11. Vibro-acoustic coupling dynamics of a finite cylindrical shell under a rotor-bearing-foundation system's nonlinear vibration excitation

    NASA Astrophysics Data System (ADS)

    Zhou, Qizheng; Wang, Deshi

    2015-07-01

    The vibro-acoustic coupling dynamics of a rotor-bearing-foundation-cylinder system are investigated. Using rotor dynamics, structure dynamics and acoustical theory, the vibro-acoustic coupling equation of a cylindrical shell under rotor-bearing-foundation system's nonlinear vibration excitations is derived based on variational principle. In order to solve the coupling equation, the influences of the shell's vibration to the rotor-bearing system are neglected, and then the dynamical equation is reduced. The nonlinear forces transmitted to the cylinder are fitted in the Fourier series by the fast Fourier translation and the harmonic balance method, and then the analytical solution of the vibro-acoustic coupling equation of the cylinder is derived. Based on inherent assumption, the analytical expressions of the acoustic radiation power and the surface velocity are given. Then bifurcation diagrams, phase diagrams, time history diagrams and spectrum graphs are employed to study the nonlinear vibration characteristics and the acoustic radiation characteristics. It is inferred that the present work proposes a semi-analytical and semi-numerical method for the nonlinear vibro-acoustic coupling system. The motions of the forces transmitted to the cylinder are periodic motions, quasi-periodic motions, and so on. The vibro-acoustic characteristics of shell are dominated by the rotation frequency of the rotor, while there are some harmonic components dominating the vibro-acoustic characteristics at resonant frequencies.

  12. Detection and modeling of the acoustic perturbation produced by the launch of the Space Shuttle using the Global Positioning System

    NASA Astrophysics Data System (ADS)

    Bowling, T. J.; Calais, E.; Dautermann, T.

    2010-12-01

    Rocket launches are known to produce infrasonic pressure waves that propagate into the ionosphere where coupling between electrons and neutral particles induces fluctuations in ionospheric electron density observable in GPS measurements. We have detected ionospheric perturbations following the launch of space shuttle Atlantis on 11 May 2009 using an array of continually operating GPS stations across the Southeastern coast of the United States and in the Caribbean. Detections are prominent to the south of the westward shuttle trajectory in the area of maximum coupling between the acoustic wave and Earth’s magnetic field, move at speeds consistent with the speed of sound, and show coherency between stations covering a large geographic range. We model the perturbation as an explosive source located at the point of closest approach between the shuttle path and each sub-ionospheric point. The neutral pressure wave is propagated using ray tracing, resultant changes in electron density are calculated at points of intersection between rays and satellite-to-reciever line-of-sight, and synthetic integrated electron content values are derived. Arrival times of the observed and synthesized waveforms match closely, with discrepancies related to errors in the apriori sound speed model used for ray tracing. Current work includes the estimation of source location and energy.

  13. A lateral field excited ZnO film bulk acoustic wave sensor working in viscous environments

    NASA Astrophysics Data System (ADS)

    Chen, Da; Wang, Jingjing; Xu, Yan; Li, Dehua; Zhang, Liuyin; Liu, Weihui

    2013-09-01

    We present a lateral field excited ZnO film bulk acoustic resonator (FBAR) operated in pure-shear mode and analyze its performances in viscous liquids. The electrodes of the device are located on the film surface and normal to the c-axis of the ZnO film. The proposed device works near 1.44 GHz with a Q-factor up to 360 in air and 310 in water, which are higher than those of the quasi-shear thickness field excited FBAR. The resonant frequency is decreased with the increasing square root of the product of the viscosity and density with a linear dependence in the viscosity below 148.7 mPa s. The mass sensitivity of 670 Hz cm2 ng-1 was measured by monitoring the frequency change during the volatilization of saline solution loaded on the resonator. In addition, the levels of the noise and the mass resolutions were measured in various viscous environments. The proposed device yields the mass resolution of 670 Hz cm2 ng-1 and the high mass resolution of 0.06 ng cm-2. These results indicated that the lateral field excited ZnO FBAR had superior sensitivity for the bio-sensing applications in viscous biological liquids.

  14. Exciting and propagating characteristics of two coexisting kinetic geodesic acoustic modes in the edge of plasma

    NASA Astrophysics Data System (ADS)

    Kong, D. F.; Liu, A. D.; Lan, T.; Yu, C. X.; Cheng, J.; Qiu, Z. Y.; Zhao, H. L.; Shen, H. G.; Yan, L. W.; Dong, J. Q.; Xu, M.; Zhao, K. J.; Duan, X. R.; Liu, Y.; Chen, R.; Zhang, S. B.; Sun, X.; Xie, J. L.; Li, H.; Liu, W. D.

    2017-04-01

    Coexisting dual kinetic geodesic acoustic modes (KGAMs) with similar characteristics have been observed with Langmuir probe arrays in the edge plasma of HL-2A tokamak with low density Ohmic discharge. The dual KGAMs are named a low-frequency GAM (LFGAM) and a high-frequency GAM (HFGAM), respectively. By changing the line averaged density from 1.0× {{10}19}~{{\\text{m}}-3} to 0.7× {{10}19}~{{\\text{m}}-3} , the study of n e and T e profiles indicate that collision damping rate plays a crucial role on exciting of dual KGAMs, especially for the higher frequency branch (HFGAM). With the application of modulating techniques, we provide direct proof that nonlinear interactions between GAMs and ambient turbulence (AT) show great difference at different radial positions. At the exciting position of GAM, the amplitude modulation of AT is dominant, indicating that GAM is generated in the energy-conserving triad interaction. After the exciting of GAMs, they will propagate both inward and outward. During the propagation, the phase modulation of AT is dominant, GAMs can rarely gain energy from AT, yet they can give back-reactions on AT through shearing effect.

  15. Enhanced water removal in a fuel cell stack by droplet atomization using structural and acoustic excitation

    NASA Astrophysics Data System (ADS)

    Palan, Vikrant; Shepard, W. Steve

    This work examines new methods for enhancing product water removal in fuel cell stacks. Vibration and acoustic based methods are proposed to atomize condensed water droplets in the channels of a bipolar plate or on a membrane electrode assembly (MEA). The vibration levels required to atomize water droplets of different sizes are first examined using two different approaches: (1) exciting the droplet at the same energy level required to form that droplet; and (2) by using a method called 'vibration induced droplet atomization', or VIDA. It is shown analytically that a 2 mm radius droplet resting on a bipolar-like plate can be atomized by inducing acceleration levels as low as 250 g at a certain frequency. By modeling the direct structural excitation of a simplified bipolar plate using a realistic source, the response levels that can be achieved are then compared with those required levels. Furthermore, a two-cell fuel cell finite element model and a boundary element model of the MEA were developed to demonstrate that the acceleration levels required for droplet atomization may be achieved in both the bipolar plate as well as the MEA through proper choice of excitation frequency and source strength.

  16. Evaluation of Acoustic Emission NDE of Composite Crew Module Service Module/Alternate Launch Abort System (CCM SM/ALAS) Test Article Failure Tests

    NASA Technical Reports Server (NTRS)

    Horne, Michael R.; Madaras, Eric I.

    2010-01-01

    Failure tests of CCM SM/ALAS (Composite Crew Module Service Module / Alternate Launch Abort System) composite panels were conducted during July 10, 2008 and July 24, 2008 at Langley Research Center. This is a report of the analysis of the Acoustic Emission (AE) data collected during those tests.

  17. Electromagnetic Launch Vehicle Fairing and Acoustic Blanket Model of Received Power Using FEKO

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Stanley, James E.; Wahid, Parveen F.

    2011-01-01

    Evaluating the impact of radio frequency transmission in vehicle fairings is important to electromagnetically sensitive spacecraft. This study employs the multilevel fast multipole method (MLFMM) from a commercial electromagnetic tool, FEKO, to model the fairing electromagnetic environment in the presence of an internal transmitter with improved accuracy over industry applied techniques. This fairing model includes material properties representative of acoustic blanketing commonly used in vehicles. Equivalent surface material models within FEKO were successfully applied to simulate the test case. Finally, a simplified model is presented using Nicholson Ross Weir derived blanket material properties. These properties are implemented with the coated metal option to reduce the model to one layer within the accuracy of the original three layer simulation.

  18. Analytical procedures for estimating structural response to acoustic fields generated by advanced launch systems, phase 2

    NASA Technical Reports Server (NTRS)

    Elishakoff, Isaac; Lin, Y. K.; Zhu, Li-Ping; Fang, Jian-Jie; Cai, G. Q.

    1994-01-01

    This report supplements a previous report of the same title submitted in June, 1992. It summarizes additional analytical techniques which have been developed for predicting the response of linear and nonlinear structures to noise excitations generated by large propulsion power plants. The report is divided into nine chapters. The first two deal with incomplete knowledge of boundary conditions of engineering structures. The incomplete knowledge is characterized by a convex set, and its diagnosis is formulated as a multi-hypothesis discrete decision-making algorithm with attendant criteria of adaptive termination.

  19. Observations of the frequencies in a sphere wake and of drag increase by acoustic excitation

    NASA Technical Reports Server (NTRS)

    Kim, H. J.; Durbin, P. A.

    1988-01-01

    Vortex shedding and instability wave frequencies have been measured in the wakes of spheres in the Reynolds number range 500 less than Re less than 60,000. The effect of acoustic excitation was examined and an interaction between the two frequency modes was found at the lower Reynolds numbers; through this interaction, external forcing at the instability frequency could change the vortex shedding frequency. The development of the mean wake was manipulated by forcing near to the dominant shear layer instability frequency. With this forcing, the separated shear layer moved closer to the surface of the sphere and the reversed flow region of the wake was shortened. Concomitantly, the base pressure decreased and drag increased.

  20. Wave-particle dynamics of wave breaking in the self-excited dust acoustic wave.

    PubMed

    Teng, Lee-Wen; Chang, Mei-Chu; Tseng, Yu-Ping; I, Lin

    2009-12-11

    The wave-particle microdynamics in the breaking of the self-excited dust acoustic wave growing in a dusty plasma liquid is investigated through directly tracking dust micromotion. It is found that the nonlinear wave growth and steepening stop as the mean oscillating amplitude of dust displacement reaches about 1/k (k is the wave number), where the vertical neighboring dust trajectories start to crossover and the resonant wave heating with uncertain crest trapping onsets. The dephased dust oscillations cause the abrupt dropping and broadening of the wave crest after breaking, accompanied by the transition from the liquid phase with coherent dust oscillation to the gas phase with chaotic dust oscillation. Corkscrew-shaped phase-space distributions measured at the fixed phases of the wave oscillation cycle clearly indicate how dusts move in and constitute the evolving waveform through dust-wave interaction.

  1. Structural-acoustic optimization of structures excited by turbulent boundary layer flow

    NASA Astrophysics Data System (ADS)

    Shepherd, Micah R.

    In order to reduce noise radiation of aircraft or marine panels, a general structural-acoustic optimization technique is presented. To compute the structural-acoustic response, a modal approach based on finite element / boundary element analysis is used which can easily incorporate fluid loading, added structures and static pre-loads. Simple deterministic or complex random forcing functions are included in the analysis by transforming their cross-spectral density matrices to modal space. Particular emphasis is placed in this dissertation on structures excited by the fluctuating pressures due to turbulent boundary layer (TBL) flow. An efficient frequency-spacing is also used to minimize evaluation time but ensure accuracy. The response from the structural-acoustic analysis is coupled to an evolutionary strategy with covariance matrix adaptation (CMA-ES) to find the best design for low noise and weight. CMA-ES, a stochastic optimizer with robust search properties, samples candidate solutions from a multi-variate normal distribution and adapts the covariance matrix to favor good solutions. The optimization procedure is validated by minimizing the sound radiated by a point-driven ribbed panel and comparing the optimization results to an exhaustive search of the design space. Structural-acoustic optimization is then performed on a curved marine panel with heavy fluid loading excited by slow TBL flow. A weighted combination of noise radiation and mass are minimized by changing the thickness of strips and patches of elements. An uncorrelated pressure approximation is used to estimate the modal force due to TBL flow thus reducing the evaluation time required to compute the objective function. The results show that the best noise reduction is achieved by minimizing the modal acceptance of energy by the panel. This is equivalent to pushing the structural modes away from the peak frequency range of the forcing function. Additionally, the Pareto trade-off curve between total

  2. Noise reduction of a composite cylinder subjected to random acoustic excitation

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Beyer, T.

    1989-01-01

    Interior and exterior noise measurements were conducted on a stiffened composite floor-equipped cylinder, with and without an interior trim installed. Noise reduction was obtained for the case of random acoustic excitation in a diffuse field; the frequency range of interest was 100-800-Hz one-third octave bands. The measured data were compared with noise reduction predictions from the Propeller Aircraft Interior Noise (PAIN) program and from a statistical energy analysis. Structural model parameters were not predicted well by the PAIN program for the given input parameters; this resulted in incorrect noise reduction predictions for the lower one-third octave bands where the power flow into the interior of the cylinder was predicted on a mode-per-mode basis.

  3. Excitation of kinetic geodesic acoustic modes by drift waves in nonuniform plasmas

    SciTech Connect

    Qiu, Z.; Chen, L.; Zonca, F.

    2014-02-15

    Effects of system nonuniformities and kinetic dispersiveness on the spontaneous excitation of Geodesic Acoustic Mode (GAM) by Drift Wave (DW) turbulence are investigated based on nonlinear gyrokinetic theory. The coupled nonlinear equations describing parametric decay of DW into GAM and DW lower sideband are derived and then solved both analytically and numerically to investigate the effects on the parametric decay process due to system nonuniformities, such as nonuniform diamagnetic frequency, finite radial envelope of DW pump, and kinetic dispersiveness. It is found that the parametric decay process is a convective instability for typical tokamak parameters when finite group velocities of DW and GAM associated with kinetic dispersiveness and finite radial envelope are taken into account. When, however, nonuniformity of diamagnetic frequency is taken into account, the parametric decay process becomes, time asymptotically, a quasi-exponentially growing absolute instability.

  4. The excitation and detection of lamb waves with planar coil electromagnetic acoustic transducers.

    PubMed

    Wilcox, Paul D; Lowe, Michael J S; Cawley, Peter

    2005-12-01

    Planar coil electromagnetic acoustic transducers (EMATs) are investigated for the excitation and detection of Lamb waves in nonferromagnetic metallic wave-guides. Such EMATs are attractive for certain applications due to their omni-directional sensitivity to wave modes with predominantly in-plane surface displacement, such as the So Lamb wave mode. A model is developed that enables the modal content of the radiated Lamb wave field from a transmitting EMAT to be calculated, and the output voltage from a receiving EMAT to be predicted when a Lamb wave mode is incident on it. The predictions from this model are compared with experimental data obtained from 12 different EMATs tested on a 5-mm thick aluminum plate, and good agreement is obtained. The model then is used to analyze the different effects that contribute to the overall Lamb wave modal sensitivity of an EMAT. The relationship between coil geometry and wavelength is examined.

  5. Effect of Particle Damping on an Acoustically Excited Curved Vehicle Panel Structure with varied Equipment Assemblies

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    Particle dampers provide a mechanism for diverting energy away from resonant structural vibrations. This experimental study provides data from trials to determine how effective use of these dampers might be for equipment mounted to a curved orthogrid vehicle panel. Trends for damping are examined for variations in damper fill level, component mass, and excitation energy. A significant response reduction at the component level would suggest that comparatively small, thoughtfully placed, particle dampers might be advantageously used in vehicle design. The results of this test will be compared with baseline acoustic response tests and other follow-on testing involving a range of isolation and damping methods. Instrumentation consisting of accelerometers, microphones, and still photography data will be collected to correlate with the analytical results.

  6. Ultrafast atomic-scale visualization of acoustic phonons generated by optically excited quantum dots.

    PubMed

    Vanacore, Giovanni M; Hu, Jianbo; Liang, Wenxi; Bietti, Sergio; Sanguinetti, Stefano; Carbone, Fabrizio; Zewail, Ahmed H

    2017-07-01

    Understanding the dynamics of atomic vibrations confined in quasi-zero dimensional systems is crucial from both a fundamental point-of-view and a technological perspective. Using ultrafast electron diffraction, we monitored the lattice dynamics of GaAs quantum dots-grown by Droplet Epitaxy on AlGaAs-with sub-picosecond and sub-picometer resolutions. An ultrafast laser pulse nearly resonantly excites a confined exciton, which efficiently couples to high-energy acoustic phonons through the deformation potential mechanism. The transient behavior of the measured diffraction pattern reveals the nonequilibrium phonon dynamics both within the dots and in the region surrounding them. The experimental results are interpreted within the theoretical framework of a non-Markovian decoherence, according to which the optical excitation creates a localized polaron within the dot and a travelling phonon wavepacket that leaves the dot at the speed of sound. These findings indicate that integration of a phononic emitter in opto-electronic devices based on quantum dots for controlled communication processes can be fundamentally feasible.

  7. Acoustic resonance excitation of turbulent heat transfer and flow reattachment downstream of a fence

    NASA Astrophysics Data System (ADS)

    Selcan, Claudio; Cukurel, Beni; Shashank, Judah

    2016-10-01

    The current work investigates the aero-thermal impact of standing sound waves, excited in a straight channel geometry, on turbulent, separating and reattaching flow over a fence. Effects of distinct frequency resonant forcing (ReH = 10,050 and f = 122 Hz) are quantified by wall static pressure measurements and detailed convective heat transfer distributions via liquid crystal thermometry. Acoustic boundary conditions are numerically predicted and the computed longitudinal resonance mode shapes are experimentally verified by surface microphone measurements. Findings indicate the presence of a resonant sound field to exert strong influence on local heat transfer downstream of the fence, whereas the boundary layer upstream of the obstacle remains notable unaffected. Upstream shift of the maximum heat transfer location and an earlier pressure recovery indicate a reduction in time averaged flow reattachment length of up to 37 %. Although the streamwise peak Nusselt increased by only 5 %, the heat transfer level in the vicinity of the unexcited reattachment zone was locally enhanced up to 25 %. Despite prominent impact of resonant forcing on the fence wake flow, the total pressure drop penalty remained invariant. Observations demonstrate the significant aero-thermal implications of shear layer excitation by standing sound waves superimposed on the channel flow field.

  8. Acoustic radiation force impulse (ARFI) imaging of zebrafish embryo by high-frequency coded excitation sequence.

    PubMed

    Park, Jinhyoung; Lee, Jungwoo; Lau, Sien Ting; Lee, Changyang; Huang, Ying; Lien, Ching-Ling; Kirk Shung, K

    2012-04-01

    Acoustic radiation force impulse (ARFI) imaging has been developed as a non-invasive method for quantitative illustration of tissue stiffness or displacement. Conventional ARFI imaging (2-10 MHz) has been implemented in commercial scanners for illustrating elastic properties of several organs. The image resolution, however, is too coarse to study mechanical properties of micro-sized objects such as cells. This article thus presents a high-frequency coded excitation ARFI technique, with the ultimate goal of displaying elastic characteristics of cellular structures. Tissue mimicking phantoms and zebrafish embryos are imaged with a 100-MHz lithium niobate (LiNbO₃) transducer, by cross-correlating tracked RF echoes with the reference. The phantom results show that the contrast of ARFI image (14 dB) with coded excitation is better than that of the conventional ARFI image (9 dB). The depths of penetration are 2.6 and 2.2 mm, respectively. The stiffness data of the zebrafish demonstrate that the envelope is harder than the embryo region. The temporal displacement change at the embryo and the chorion is as large as 36 and 3.6 μm. Consequently, this high-frequency ARFI approach may serve as a remote palpation imaging tool that reveals viscoelastic properties of small biological samples.

  9. Prediction of interior noise due to random acoustic or turbulent boundary layer excitation using statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.

    1990-01-01

    The feasibility of predicting interior noise due to random acoustic or turbulent boundary layer excitation was investigated in experiments in which a statistical energy analysis model (VAPEPS) was used to analyze measurements of the acceleration response and sound transmission of flat aluminum, lucite, and graphite/epoxy plates exposed to random acoustic or turbulent boundary layer excitation. The noise reduction of the plate, when backed by a shallow cavity and excited by a turbulent boundary layer, was predicted using a simplified theory based on the assumption of adiabatic compression of the fluid in the cavity. The predicted plate acceleration response was used as input in the noise reduction prediction. Reasonable agreement was found between the predictions and the measured noise reduction in the frequency range 315-1000 Hz.

  10. Non-contact test set-up for aeroelasticity in a rotating turbomachine combining a novel acoustic excitation system with tip-timing

    NASA Astrophysics Data System (ADS)

    Freund, O.; Montgomery, M.; Mittelbach, M.; Seume, J. R.

    2014-03-01

    Due to trends in aero-design, aeroelasticity becomes increasingly important in modern turbomachines. Design requirements of turbomachines lead to the development of high aspect ratio blades and blade integral disc designs (blisks), which are especially prone to complex modes of vibration. Therefore, experimental investigations yielding high quality data are required for improving the understanding of aeroelastic effects in turbomachines. One possibility to achieve high quality data is to excite and measure blade vibrations in turbomachines. The major requirement for blade excitation and blade vibration measurements is to minimize interference with the aeroelastic effects to be investigated. Thus in this paper, a non-contact—and thus low interference—experimental set-up for exciting and measuring blade vibrations is proposed and shown to work. A novel acoustic system excites rotor blade vibrations, which are measured with an optical tip-timing system. By performing measurements in an axial compressor, the potential of the acoustic excitation method for investigating aeroelastic effects is explored. The basic principle of this method is described and proven through the analysis of blade responses at different acoustic excitation frequencies and at different rotational speeds. To verify the accuracy of the tip-timing system, amplitudes measured by tip-timing are compared with strain gage measurements. They are found to agree well. Two approaches to vary the nodal diameter (ND) of the excited vibration mode by controlling the acoustic excitation are presented. By combining the different excitable acoustic modes with a phase-lag control, each ND of the investigated 30 blade rotor can be excited individually. This feature of the present acoustic excitation system is of great benefit to aeroelastic investigations and represents one of the main advantages over other excitation methods proposed in the past. In future studies, the acoustic excitation method will be used

  11. Excitation of Electron Acoustic Waves in Plasmas of the SINP-MaPLE Device

    NASA Astrophysics Data System (ADS)

    Chowdhury, Satyajit; Biswas, Subir; Chakrabrati, Nikhil; Pal, Rabindranath

    2016-10-01

    Electron acoustic wave (EAW) is the low frequency branch of the undamped electrostatic plasma wave and has low phase velocity. In order to overcome Landau damping the EAW needs a non-Maxwellian electron velocity distribution with a flat region near the phase velocity, or equivalently, a plasma with two temperature electron species with a relative velocity between them. The ECR produced plasmas of the MaPLE device at Saha Institute of Nuclear Physics provide such characteristics as observed by retarded field energy analyzer and single Langmuir probe. Experiments are carried out to exploit this feature by putting a negatively biased mesh launcher inside the plasma and energizing it with sinusoidal voltages from a function generator with frequencies varying near the ion plasma frequency. Circular mesh probes along the axis of the device serve as detectors for wave propagation. Experimental results show EAWs are indeed launched and propagate along the magnetic field direction. The dispersion curve experimentally obtained shows the phase velocity matching satisfactorily with the estimated theoretical values. Changing the bias on the launcher the electron distribution function is varied, which, in turn, controls the wave amplitude. Detailed experimental results will be presented. Department of Atomic Energy, Govt. of India.

  12. MONITORING POWER PLANT EFFICIENCY USING THE MICROWAVE-EXCITED THERMAL-ACOUSTIC EFFECT TO MEASURE UNBURNED CARBON

    SciTech Connect

    Robert C. Brown; Robert J. Weber; Jeffrey J. Swetelitsch

    2005-01-01

    The objective of this project is to explore microwave-excited thermal-acoustic (META) phenomena for quantitative analysis of granular and powdered materials, with the culmination of the research to be an on-line carbon-in-ash monitor for coal-fired power plants. This technique of analyzing unburned carbon in fly ash could be a less tedious and time consuming method as compared to the traditional LOI manual procedure. Phase 1 of the research focused on off-line single-frequency thermal-acoustic measurements where an off-line fly ash monitor was constructed that could operate as analytical tool to explore instrument and methodology parameters for quantifying the microwave-excited thermal-acoustic effect of carbon in fly ash, and it was determined that the off-line thermal-acoustic technique could predict the carbon content of a random collection of fly ashes with a linear correlation constant of R{sup 2} = 0.778. Much higher correlations are expected for fly ashes generated from a single boiler. Phase 2 of the research developing a methodology to generate microwave spectra of various powders, including fly ash, coal, and inorganic minerals, and to determine if these microwave spectra could be used for chemical analyses. Although different minerals produced different responses, higher resolution microwave spectra would be required to be able to distinguish among minerals. Phase 3 of the research focused on the development of an on-line fly ash monitor that could be adapted to measure either a thermal-acoustic or thermal-elastic response to due microwave excitation of fly ash. The thermal-acoustic response was successfully employed for this purpose but the thermal-elastic response was too weak to yield a useful on-line device.

  13. Photo-acoustic excitation and detection of guided ultrasonic waves in bone samples covered by a soft coating layer

    NASA Astrophysics Data System (ADS)

    Zhao, Zuomin; Moilanen, Petro; Karppinen, Pasi; Määttä, Mikko; Karppinen, Timo; Hæggström, Edward; Timonen, Jussi; Myllylä, Risto

    2012-12-01

    Photo-acoustic (PA) excitation was combined with skeletal quantitative ultrasound (QUS) for multi-mode ultrasonic assessment of human long bones. This approach permits tailoring of the ultrasonic excitation and detection so as to efficiently detect the fundamental flexural guided wave (FFGW) through a coating of soft tissue. FFGW is a clinically relevant indicator of cortical thickness. An OPO laser with tunable optical wavelength, was used to excite a photo-acoustic source in the shaft of a porcine femur. Ultrasonic signals were detected by a piezoelectric transducer, scanning along the long axis of the bone, 20-50 mm away from the source. Five femurs were measured without and with a soft coating. The coating was made of an aqueous gelatin-intralipid suspension that optically and acoustically mimicked real soft tissue. An even coating thickness was ensured by using a specific mold. The optical wave length of the source (1250 nm) was tuned to maximize the amplitude of FFGW excitation at 50 kHz frequency. The experimentally determined FFGW phase velocity in the uncoated samples was consistent with that of the fundamental antisymmetric Lamb mode (A0). Using appropriate signal processing, FFGW was also identified in the coated bone samples, this time with a phase velocity consistent with that theoretically predicted for the first mode of a fluid-solid bilayer waveguide (BL1). Our results suggest that photo-acoustic quantitative ultrasound enables assessment of the thickness-sensitive FFGW in bone through a layer of soft tissue. Photo-acoustic characterization of the cortical bone thickness may thus become possible.

  14. Coupling between hydrodynamics, acoustics, and heat release in a self-excited unstable combustor

    NASA Astrophysics Data System (ADS)

    Harvazinski, Matthew E.; Huang, Cheng; Sankaran, Venkateswaran; Feldman, Thomas W.; Anderson, William E.; Merkle, Charles L.; Talley, Douglas G.

    2015-04-01

    The unsteady gas dynamic field in a closed combustor is determined by the nonlinear interactions between chamber acoustics, hydrodynamics, and turbulent combustion that can energize these modes. These interactions are studied in detail using hybrid RANS/large eddy simulations (RANS = Reynolds Averaged Navier-Stokes) of a non-premixed, high-pressure laboratory combustor that produces self-excited longitudinal instabilities. The main variable in the study is the relative acoustic length between the combustion chamber and the tube that injects oxidizer into the combustor. Assuming a half-wave (closed-closed) combustion chamber, the tube lengths approximately correspond to quarter-, 3/8-, and half-wave resonators that serve to vary the phasing between the acoustic modes in the tube and the combustion chamber. The simulation correctly predicts the relatively stable behavior measured with the shortest tube and the very unstable behavior measured with the intermediate tube. Unstable behavior is also predicted for the longest tube, a case for which bifurcated stability behavior was measured in the experiment. In the first (stable) configuration, fuel flows into the combustor uninterrupted, and heat release is spatially continuous with a flame that remains attached to the back step. In the second (unstable) configuration, a cyclic process is apparent comprising a disruption in the fuel flow, subsequent detachment of the flame from the back step, and accumulation of fuel in the recirculation zone that ignites upon arrival of a compression wave reflected from the downstream boundary of the combustion chamber. The third case (mixed stable/unstable) shares features with both of the other cases. The major difference between the two cases predicted to be unstable is that, in the intermediate length tube, a pressure wave reflection inside the tube pushes unburnt fuel behind the back step radially outward, leading to a post-coupled reignition mechanism, while in the case of the

  15. Extraction of the acoustic component of a turbulent flow exciting a plate by inverting the vibration problem

    NASA Astrophysics Data System (ADS)

    Lecoq, D.; Pézerat, C.; Thomas, J.-H.; Bi, W. P.

    2014-06-01

    An improvement of the Force Analysis Technique (FAT), an inverse method of vibration, is proposed to identify the low wavenumbers including the acoustic component of a turbulent flow that excites a plate. This method is a significant progress since the usual techniques of measurements with flush-mounted sensors are not able to separate the acoustic and the aerodynamic energies of the excitation because the aerodynamic component is too high. Moreover, the main cause of vibration or acoustic radiation of the structure might be due to the acoustic part by a phenomenon of spatial coincidence between the acoustic wavelengths and those of the plate. This underlines the need to extract the acoustic part. In this work, numerical experiments are performed to solve both the direct and inverse problems of vibration. The excitation is a turbulent boundary layer and combines the pressure field of the Corcos model and a diffuse acoustic field. These pressures are obtained by a synthesis method based on the Cholesky decomposition of the cross-spectra matrices and are used to excite a plate. Thus, the application of the inverse problem FAT that requires only the vibration data shows that the method is able to identify and to isolate the acoustic part of the excitation. Indeed, the discretization of the inverse operator (motion equation of the plate) acts as a low-pass wavenumber filter. In addition, this method is simple to implement because it can be applied locally (no need to know the boundary conditions), and measurements can be carried out on the opposite side of the plate without affecting the flow. Finally, an improvement of FAT is proposed. It regularizes optimally and automatically the inverse problem by analyzing the mean quadratic pressure of the reconstructed force distribution. This optimized FAT, in the case of the turbulent flow, has the advantage of measuring the acoustic component up to higher frequencies even in the presence of noise. the aerodynamic component

  16. Micro-origin of no-trough trapping in self-excited nonlinear dust acoustic waves.

    PubMed

    Chang, Mei-Chu; Teng, Lee-Wen; I, Lin

    2012-04-01

    We experimentally investigate the micro-origin of the absence of trough trapping in nonlinear traveling dust acoustic waves self-excited by the downward ion flow in the dissipative dusty plasma. The wave forms of dust density, the drag force from the background neutrals, ions, and dusts, and the effective potential energy for dusts are constructed by tracking dust motion and measuring the velocity and the position-dependent forces. The tilted washboard type potential wave form with a slight phase lead to the dust density wave form is obtained. It provides sufficient kinetic energy to compensate drag dissipation and move dusts from the dust density trough to the crest front. The dusts with sufficient energy overcome the downward pushing by the crest front, climb over the crest, and sustain the oscillatory motion with upward drift. Those dusts with insufficient energy to climb over the potential barrier of the crest are trapped in and move downward with the crest front, until kicked upward by fluctuation. The upward neutral dominated drag force prevents them from sliding down the potential energy hill at the crest front and further oscillating in the trough. It leads to the absence of trough trapping.

  17. Asymptotic modal analysis of a rectangular acoustic cavity excited by wall vibration

    NASA Technical Reports Server (NTRS)

    Peretti, Linda F.; Dowell, Earl H.

    1992-01-01

    Asymptotic modal analysis, a method that has recently been developed for structural dynamical systems, has been applied to a rectangular acoustic cavity. The cavity had a flexible vibrating portion on one wall, and the other five walls were rigid. Banded white noise was transmitted through the flexible portion (plate) only. Both the location along the wall and the size of the plate were varied. The mean square pressure levels of the cavity interior were computed as a ratio of the result obtained from classical modal analysis to that obtained from asymptotic modal analysis for the various plate configurations. In general, this ratio converged to 1.0 as the number of responding modes increased. Intensification effects were found due to both the excitation location and the response location. The asymptotic modal analysis method was both efficient and accurate in solving the given problem. The method has advantages over the traditional methods that are used for solving dynamics problems with a large number of responding modes.

  18. Real-time monitoring of human blood clotting using a lateral excited film bulk acoustic resonator

    NASA Astrophysics Data System (ADS)

    Chen, Da; Wang, Jingjng; Wang, Peng; Guo, Qiuquan; Zhang, Zhen; Ma, Jilong

    2017-04-01

    Frequent assay of hemostatic status is an essential issue for the millions of patients using anticoagulant drugs. In this paper, we presented a micro-fabricated film bulk acoustic sensor for the real-time monitoring of blood clotting and the measurement of hemostatic parameters. The device was made of an Au/ZnO/Si3N4 film stack and excited by a lateral electric field. It operated under a shear mode resonance with the frequency of 1.42 GHz and had a quality factor of 342 in human blood. During the clotting process of blood, the resonant frequency decreased along with the change of blood viscosity and showed an apparent step-ladder curve, revealing the sequential clotting stages. An important hemostatic parameter, prothrombin time, was quantitatively determined from the frequency response for different dilutions of the blood samples. The effect of a typical anticoagulant drug (heparin) on the prothrombin time was exemplarily shown. The proposed sensor displayed a good consistency and clinical comparability with the standard coagulometric methods. Thanks to the availability of direct digital signals, excellent potentials of miniaturization and integration, the proposed sensor has promising application for point-of-care coagulation technologies.

  19. Cryogenic oxygen jet response to transverse acoustic excitation with the first transverse and the first combined longitudinal-transverse modes

    NASA Astrophysics Data System (ADS)

    Hardi, J. S.; Oschwald, M.

    2016-07-01

    The intact length of the dense oxygen core from an oxygen-hydrogen shear coaxial rocket injector was measured. The measurements were made in a rectangular rocket combustor with optical access and acoustic forcing. The combustor was operated at chamber pressures of 40 and 60 bar, with either ambient temperature or cryogenic hydrogen. The multielement injection spray is subjected to forced transverse gas oscillations of two different acoustic resonance modes; the first transverse (1T) mode at 4200 Hz and the first combined longitudinal-transverse (1L1T) at 5500 Hz. Intact core length is measured from high-speed shadowgraph imaging. The dependence of intact core length with increasing acoustic amplitude is compared for the two modes of excitation.

  20. Frequency-shift vibro-acoustic modulation driven by low-frequency broadband excitations in a bistable cantilever oscillator

    NASA Astrophysics Data System (ADS)

    He, Qingbo; Xu, Yanyan; Lu, Siliang; Shao, Yong

    2017-03-01

    This paper reports a frequency-shift vibro-acoustic modulation (VAM) effect in a bistable microcracked cantilever oscillator. Low-frequency broadband excitations induced a VAM effect with a shifted modulation frequency through involving a microcracked metal beam in a bistable oscillator model. We used nonlinear dynamics equations and principles to describe the mechanism of a bistable oscillator whose natural frequency varied as the oscillation amplitude increased. We demonstrated this frequency-shift VAM effect using a prototype bistable oscillator model designed to efficiently detect microcracks in solid materials via the VAM effect using ambient vibration excitations.

  1. The theoretical and experimental study of the nonlinear and chaotic response of curved panels to intense acoustic excitation

    NASA Technical Reports Server (NTRS)

    Ng, C. F.

    1988-01-01

    Assuming a single-mode transverse displacement, a simple formula is derived for the transverse load-displacement relationship of a plate under in-plane compression. The formula is used to derive a simple analytical expression for the nonlinear dynamic response of postbuckled plates under sinusoidal or random excitation. The highly nonlinear motion of snap-through can be easily interpreted using the single-mode formula. Experimental results are obtained using buckled and cylindrical aluminum panels using discrete frequency and broadband excitation of mechanical and acoustic forces.

  2. Modified impulse method for the measurement of the frequency response of acoustic filters to weakly nonlinear transient excitations

    PubMed

    Payri; Desantes; Broatch

    2000-02-01

    In this paper, a modified impulse method is proposed which allows the determination of the influence of the excitation characteristics on acoustic filter performance. Issues related to nonlinear propagation, namely wave steepening and wave interactions, have been addressed in an approximate way, validated against one-dimensional unsteady nonlinear flow calculations. The results obtained for expansion chambers and extended duct resonators indicate that the amplitude threshold for the onset of nonlinear phenomena is related to the geometry considered.

  3. System and method for characterizing voiced excitations of speech and acoustic signals, removing acoustic noise from speech, and synthesizing speech

    DOEpatents

    Burnett, Greg C.; Holzrichter, John F.; Ng, Lawrence C.

    2002-01-01

    Low power EM waves are used to detect motions of vocal tract tissues of the human speech system before, during, and after voiced speech. A voiced excitation function is derived. The excitation function provides speech production information to enhance speech characterization and to enable noise removal from human speech.

  4. Comparison of acoustic and seismic excitation, propagation, and scattering at an air-ground interface containing a mine-like inclusion.

    PubMed

    Muir, Thomas G; Costley, R Daniel; Sabatier, James M

    2014-01-01

    Finite element methods are utilized to model and compare the use of both a remote loudspeaker and a vertical shaker in the generation of sound and shear and interface waves in an elastic solid containing an imbedded elastic scatterer, which is resonant. Results for steady state and transient insonification are presented to illustrate excitation, propagation, and scattering mechanisms and effects. Comparisons of acoustic and vibratory excitation of the solid interface are made, with a view towards remote sensing of induced vibratory motion through optical measurement of the ground interface motion above the imbedded inclusion. Some advantages of the acoustic excitation method for exciting plate mode resonances in the target are observed.

  5. The immediate effects of acoustic trauma on excitation and inhibition in the inferior colliculus: A Wiener-kernel analysis.

    PubMed

    Heeringa, Amarins Nieske; van Dijk, Pim

    2016-01-01

    Noise-induced tinnitus and hyperacusis are thought to correspond to a disrupted balance between excitation and inhibition in the central auditory system. Excitation and inhibition are often studied using pure tones; however, these responses do not reveal inhibition within the excitatory pass band. Therefore, we used a Wiener-kernel analysis, complemented with singular value decomposition (SVD), to investigate the immediate effects of acoustic trauma on excitation and inhibition in the inferior colliculus (IC). Neural responses were recorded from the IC of three anesthetized albino guinea pigs before and immediately after a one-hour bilateral exposure to an 11-kHz tone of 124 dB SPL. Neural activity was recorded during the presentation of a 1-h continuous 70 dB SPL Gaussian-noise stimulus. Spike trains were subjected to Wiener-kernel analysis in which the second-order kernel was decomposed into excitatory and inhibitory components using SVD. Hearing thresholds between 3 and 22 kHz were elevated (13-47 dB) immediately after acoustic trauma. The presence and frequency tuning of excitation and inhibition in units with a low characteristic frequency (CF; < 3 kHz) was not affected, inhibition disappeared whereas excitation was not affected in mid-CF units (3 < CF < 11 kHz), and both excitation and inhibition disappeared in high-CF units (CF > 11 kHz). This specific differentiation could not be identified by tone-evoked receptive-field analysis, in which inhibitory responses disappeared in all units, along with excitatory responses in high-CF units. This study is the first to apply Wiener-kernel analysis, complemented with SVD, to study the effects of acoustic trauma on spike trains derived from the IC. With this analysis, a reduction of inhibition and preservation of good response thresholds was shown in mid-CF units immediately after acoustic trauma. These neurons may mediate noise-induced tinnitus and/or hyperacusis. Moreover, an immediate profound high

  6. Interaction of a turbulent boundary layer with a cavity-backed circular orifice and tonal acoustic excitation

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Bodony, Daniel

    2013-11-01

    Acoustic liners are effective reducers of jet exhaust and core noise and work by converting acoustic-bound energy into non-radiating, vorticity-bound energy through scattering, viscous, and non-linear processes. Modern liners are designed using highly-calibrated semi-empirical models that will not be effective for expected parameter spaces on future aircraft. The primary model limitation occurs when a turbulent boundary layer (TBL) grazes the liner; there are no physics-based methods for predicting the sound-liner interaction. We thus utilize direct numerical simulations to study the interaction of a Mach 0.5 zero pressure gradient TBL with a cavity-backed circular orifice under acoustic excitation. Acoustic field frequencies span the energy-containing range within the TBL and amplitudes range from 6 to 40 dB above the turbulent fluctuations. Impedance predictions are in agreement with NASA Langley-measured data and the simulation databases are analyzed in detail. A physics-based reduced-order model is proposed that connects the turbulence-vorticity-acoustic interaction and its accuracy and limitations are discussed. This work is funded by Aeroacoustics Research Consortium.

  7. Non-linear Alfvén wave interaction leading to resonant excitation of an acoustic mode in the laboratory

    SciTech Connect

    Dorfman, S.; Carter, T. A.

    2015-05-15

    The nonlinear three-wave interaction process at the heart of the parametric decay process is studied by launching counter-propagating Alfvén waves from antennas placed at either end of the Large Plasma Device [W. Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)]. A resonance in the beat wave response produced by the two launched Alfvén waves is observed and is identified as a damped ion acoustic mode based on the measured dispersion relation. Other properties of the interaction including the spatial profile of the beat mode and response amplitude are also consistent with theoretical predictions for a three-wave interaction driven by a nonlinear ponderomotive force. A simple damped, driven oscillator model making use of the MHD equations well-predicts most of the observations, but the width of the resonance curve is still under investigation.

  8. Minimizing the acoustic power radiated by a fluid-loaded curved panel excited by turbulent boundary layer flow.

    PubMed

    Shepherd, Micah R; Hambric, Stephen A

    2014-11-01

    In order to address noise control problems in the design stage, structural-acoustic optimization procedures can be used to find the optimal design for reduced noise or vibration. However, most structural-acoustic optimization procedures are not general enough to include both heavy fluid loading and complex forcing functions. Additionally, it can be difficult to determine and assess trade-offs between weight and sound radiation. A structural-acoustic optimization approach is presented for minimizing the radiated power of structures with heavy fluid loading excited by complex forcing functions. The procedure is demonstrated on a curved underwater panel excited by a point drive and by turbulent boundary layer flow. To facilitate more efficient analysis, an uncorrelated pressure assumption is made for the turbulent boundary layer forcing function. The thicknesses of groups of elements were used as the design variables with an adaptive covariance matrix evolutionary strategy as the search algorithm. The objective function was a weighted sum of total sound power and panel mass and the Pareto front was computed to show the optimum trade-off between the two objectives. The optimal designs are presented which illustrate the best methods for reducing radiated sound and mass simultaneously.

  9. [Thermoelastic excitation of acoustic waves in biological models under the effect of the high peak-power pulsed electromagnetic radiation of extremely high frequency].

    PubMed

    Gapeev, A B; Rubanik, A V; Pashovkin, T N; Chemeris, N K

    2007-01-01

    The capability of high peak-power pulsed electromagnetic radiation of extremely high frequency (35,27 GHz, pulse widths of 100 and 600 ns, peak power of 20 kW) to excite acoustic waves in model water-containing objects and muscular tissue of animals has been experimentally shown for the first time. The amplitude and duration of excited acoustic pulses are within the limits of accuracy of theoretical assessments and have a complex nonlinear dependence on the energy input of electromagnetic radiation supplied. The velocity of propagation of acoustic pulses in water-containing models and isolated muscular tissue of animals was close to the reference data. The excitation of acoustic waves in biological systems under the action of high peak-power pulsed electromagnetic radiation of extremely high frequency is the important phenomenon, which essentially contributes to the understanding of the mechanisms of biological effects of these electromagnetic fields.

  10. Dynamics of sessile and pendant drops excited by surface acoustic waves: Gravity effects and correlation between oscillatory and translational motions.

    PubMed

    Bussonnière, A; Baudoin, M; Brunet, P; Matar, O Bou

    2016-05-01

    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed, the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or, more generally, by an initial or dynamically induced stretching of the drop. In turn, we elucidate the origin of the resonance frequency shift, as well as the origin of the strong correlation between oscillatory and translational motion. We show that for sessile drops, the velocity is mainly determined by the amplitude of oscillation and that the saturation observed is due to the nonlinear dependence of the drop response frequency on the dynamically induced stretching.

  11. Dynamics of sessile and pendant drops excited by surface acoustic waves: Gravity effects and correlation between oscillatory and translational motions

    NASA Astrophysics Data System (ADS)

    Bussonnière, A.; Baudoin, M.; Brunet, P.; Matar, O. Bou

    2016-05-01

    When sessile droplets are excited by ultrasonic traveling surface acoustic waves (SAWs), they undergo complex dynamics with both oscillations and translational motion. While the nature of the Rayleigh-Lamb quadrupolar drop oscillations has been identified, their origin and their influence on the drop mobility remains unexplained. Indeed, the physics behind this peculiar dynamics is complex with nonlinearities involved both at the excitation level (acoustic streaming and radiation pressure) and in the droplet response (nonlinear oscillations and contact line dynamics). In this paper, we investigate the dynamics of sessile and pendant drops excited by SAWs. For pendant drops, so-far unreported dynamics are observed close to the drop detachment threshold with the suppression of the translational motion. Away from this threshold, the comparison between pendant and sessile drop dynamics allows us to identify the role played by gravity or, more generally, by an initial or dynamically induced stretching of the drop. In turn, we elucidate the origin of the resonance frequency shift, as well as the origin of the strong correlation between oscillatory and translational motion. We show that for sessile drops, the velocity is mainly determined by the amplitude of oscillation and that the saturation observed is due to the nonlinear dependence of the drop response frequency on the dynamically induced stretching.

  12. Flow and Acoustic Features of a Mach 0.9 Free Jet Using High-Frequency Excitation

    NASA Astrophysics Data System (ADS)

    Upadhyay, Puja; Alvi, Farrukh

    2016-11-01

    This study focuses on active control of a Mach 0.9 (ReD = 6 ×105) free jet using high-frequency excitation for noise reduction. Eight resonance-enhanced microjet actuators with nominal frequencies of 25 kHz (StD 2 . 2) are used to excite the shear layer at frequencies that are approximately an order of magnitude higher than the jet preferred frequency. The influence of control on mean and turbulent characteristics of the jet is studied using Particle Image Velocimetry. Additionally, far-field acoustic measurements are acquired to estimate the effect of pulsed injection on noise characteristics of the jet. Flow field measurements revealed that strong streamwise vortex pairs, formed as a result of control, result in a significantly thicker initial shear layer. This excited shear layer is also prominently undulated, resulting in a modified initial velocity profile. Also, the distribution of turbulent kinetic energy revealed that forcing results in increased turbulence levels for near-injection regions, followed by a global reduction for all downstream locations. Far-field acoustic measurements showed noise reductions at low to moderate frequencies. Additionally, an increase in high-frequency noise, mostly dominated by the actuators' resonant noise, was observed. AFOSR and ARO.

  13. Imaging and characterizing shear wave and shear modulus under orthogonal acoustic radiation force excitation using OCT Doppler variance method.

    PubMed

    Zhu, Jiang; Qu, Yueqiao; Ma, Teng; Li, Rui; Du, Yongzhao; Huang, Shenghai; Shung, K Kirk; Zhou, Qifa; Chen, Zhongping

    2015-05-01

    We report on a novel acoustic radiation force orthogonal excitation optical coherence elastography (ARFOE-OCE) technique for imaging shear wave and quantifying shear modulus under orthogonal acoustic radiation force (ARF) excitation using the optical coherence tomography (OCT) Doppler variance method. The ARF perpendicular to the OCT beam is produced by a remote ultrasonic transducer. A shear wave induced by ARF excitation propagates parallel to the OCT beam. The OCT Doppler variance method, which is sensitive to the transverse vibration, is used to measure the ARF-induced vibration. For analysis of the shear modulus, the Doppler variance method is utilized to visualize shear wave propagation instead of Doppler OCT method, and the propagation velocity of the shear wave is measured at different depths of one location with the M scan. In order to quantify shear modulus beyond the OCT imaging depth, we move ARF to a deeper layer at a known step and measure the time delay of the shear wave propagating to the same OCT imaging depth. We also quantitatively map the shear modulus of a cross-section in a tissue-equivalent phantom after employing the B scan.

  14. Experimental verification of the asymtotic modal analysis method as applied to a rectangular acoustic cavity excited by structural vibration

    NASA Astrophysics Data System (ADS)

    Peretti, L. F.; Dowell, E. H.

    1992-10-01

    An experiment was performed on a rigid wall rectangular acoustic cavity driven by a flexible plate mounted in a quarter of one end wall and excited by white noise. The experiment was designed so that the assumptions of Asymptotic Modal Analysis (AMA) were satisfied for certain bandwidths and center frequencies. Measurements of sound pressure levels at points along the boundaries and incrementally into tbe interior were taken. These were compared with the theoretical results predicted with AMA, and found to be in good agreement, particularly for moderate (1/3 octave) bandwidths and sufficiently high center frequencies. Sound pressure level measurements were also taken well into the cavity interior at various points along the 5 totally rigid walls. The AMA theory, including boundary intensification effects, was shown to be accurate provided the assumption of large number of acoustic modes is satisfied, and variables such as power spectra of the wall acceleration, frequency, and damping are slowly varying in the frequency of bandwidth.

  15. Experimental verification of the asymtotic modal analysis method as applied to a rectangular acoustic cavity excited by structural vibration

    NASA Technical Reports Server (NTRS)

    Peretti, L. F.; Dowell, E. H.

    1992-01-01

    An experiment was performed on a rigid wall rectangular acoustic cavity driven by a flexible plate mounted in a quarter of one end wall and excited by white noise. The experiment was designed so that the assumptions of Asymptotic Modal Analysis (AMA) were satisfied for certain bandwidths and center frequencies. Measurements of sound pressure levels at points along the boundaries and incrementally into tbe interior were taken. These were compared with the theoretical results predicted with AMA, and found to be in good agreement, particularly for moderate (1/3 octave) bandwidths and sufficiently high center frequencies. Sound pressure level measurements were also taken well into the cavity interior at various points along the 5 totally rigid walls. The AMA theory, including boundary intensification effects, was shown to be accurate provided the assumption of large number of acoustic modes is satisfied, and variables such as power spectra of the wall acceleration, frequency, and damping are slowly varying in the frequency of bandwidth.

  16. Experimental verification of the asymtotic modal analysis method as applied to a rectangular acoustic cavity excited by structural vibration

    NASA Technical Reports Server (NTRS)

    Peretti, L. F.; Dowell, E. H.

    1992-01-01

    An experiment was performed on a rigid wall rectangular acoustic cavity driven by a flexible plate mounted in a quarter of one end wall and excited by white noise. The experiment was designed so that the assumptions of Asymptotic Modal Analysis (AMA) were satisfied for certain bandwidths and center frequencies. Measurements of sound pressure levels at points along the boundaries and incrementally into tbe interior were taken. These were compared with the theoretical results predicted with AMA, and found to be in good agreement, particularly for moderate (1/3 octave) bandwidths and sufficiently high center frequencies. Sound pressure level measurements were also taken well into the cavity interior at various points along the 5 totally rigid walls. The AMA theory, including boundary intensification effects, was shown to be accurate provided the assumption of large number of acoustic modes is satisfied, and variables such as power spectra of the wall acceleration, frequency, and damping are slowly varying in the frequency of bandwidth.

  17. Intermolecular electron transfer from intramolecular excitation and coherent acoustic phonon generation in a hydrogen-bonded charge-transfer solid

    NASA Astrophysics Data System (ADS)

    Rury, Aaron S.; Sorenson, Shayne; Dawlaty, Jahan M.

    2016-03-01

    Organic materials that produce coherent lattice phonon excitations in response to external stimuli may provide next generation solutions in a wide range of applications. However, for these materials to lead to functional devices in technology, a full understanding of the possible driving forces of coherent lattice phonon generation must be attained. To facilitate the achievement of this goal, we have undertaken an optical spectroscopic study of an organic charge-transfer material formed from the ubiquitous reduction-oxidation pair hydroquinone and p-benzoquinone. Upon pumping this material, known as quinhydrone, on its intermolecular charge transfer resonance as well as an intramolecular resonance of p-benzoquinone, we find sub-cm-1 oscillations whose dispersion with probe energy resembles that of a coherent acoustic phonon that we argue is coherently excited following changes in the electron density of quinhydrone. Using the dynamical information from these ultrafast pump-probe measurements, we find that the fastest process we can resolve does not change whether we pump quinhydrone at either energy. Electron-phonon coupling from both ultrafast coherent vibrational and steady-state resonance Raman spectroscopies allows us to determine that intramolecular electronic excitation of p-benzoquinone also drives the electron transfer process in quinhydrone. These results demonstrate the wide range of electronic excitations of the parent of molecules found in many functional organic materials that can drive coherent lattice phonon excitations useful for applications in electronics, photonics, and information technology.

  18. Nonlinear Excitation of Acoustic Modes by Large Amplitude Alfvén waves in the Large Plasma Device (LAPD)

    NASA Astrophysics Data System (ADS)

    Dorfman, S. E.; Carter, T. A.; Pribyl, P.; Tripathi, S.; Van Compernolle, B.; Vincena, S. T.; Sydora, R. D.

    2013-12-01

    Alfvén waves, a fundamental mode of magnetized plasmas, are ubiquitous in space plasmas. While the linear behavior of these waves has been extensively studied [1], non-linear effects are important in many real systems, including the solar corona and solar wind. In particular, a parametric decay process in which a large amplitude Alfvén wave decays into an ion acoustic wave and backward propagating Alfvén wave may play an important role in the coronal heating problem. Specifically, the decay of large-amplitude Alfvén waves propagating outward from the photosphere could lead to heating of the corona by the daughter ion acoustic modes [2]. As direct observational evidence of parametric decay is limited [3], laboratory experiments may play an important role in validating simple theoretical predictions and aiding in the interpretation of space measurements. Recent counter-propagating Alfvén wave experiments in the Large Plasma Device (LAPD) have recorded the first laboratory observation of the Alfvén-acoustic mode coupling at the heart of this parametric decay instability [4]. A resonance in the beat wave response produced by the two launched Alfvén waves is observed and is identified as a damped ion acoustic mode based on the measured dispersion relation. Other properties of the interaction including the spatial profile of the beat mode and response amplitude are also consistent with theoretical predictions for a three-wave interaction driven by a nonlinear ponderomotive force. Strong damping observed after the pump Alfvén waves are turned off is under investigation; a novel ion acoustic wave launcher is under development to launch the mode directly for damping studies. New experiments also aim to identify decay instabilities from a single large-amplitude Alfvén wave. In conjunction with these experiments, gyrokinetic simulation efforts are underway to scope out the relevant parameter space. [1] W. Gekelman, et. al., Phys. Plasmas 18, 055501 (2011). [2] F

  19. Dynamic Response of X-37 Hot Structure Control Surfaces Exposed to Controlled Reverberant Acoustic Excitation

    NASA Technical Reports Server (NTRS)

    Grosveld, Ferdinand W.; Rizzi, Stephen A.; Rice, Chad E.

    2004-01-01

    This document represents a compilation of three informal reports from reverberant acoustic tests performed on X-37 hot structure control surfaces in the NASA Langley Research Center Structural Acoustics Loads and Transmission (SALT) facility. The first test was performed on a carbon-silicone carbide flaperon subcomponent on February 24, 2004. The second test was performed on a carbon-carbon ruddervator subcomponent on May 27, 2004. The third test was performed on a carbon-carbon flaperon subcomponent on June 30, 2004.

  20. Interaction of electronic excitations of Tm3+ ions with acoustic vibrations in KTm(MoO4)2

    NASA Astrophysics Data System (ADS)

    Kamenskyi, D.; Poperezhai, S.; Gogoi, P.; Engelkamp, H.; Maan, J. C.; Wosnitza, J.; Kut'ko, V.

    2014-01-01

    Electron paramagnetic resonance spectra of KTm(MoO4)2 were measured as a function of magnetic field between 3 and 11.5 cm-1 at T =2 K. We found that in addition to the absorption line caused by the electronic excitation of Tm3+ ions, the spectra contain sidebands. Far-infrared transmission measured with polarized light from 10 to 75 cm-1 revealed vibration modes at 16.7 and 25.7 cm-1 for polarizations Eω∥a and Eω∥c, respectively. We show that sidebands in the spectra of paramagnetic resonance result from a parametric resonance between the electronic excitations of the Tm3+ ions and the acoustic vibrations of the crystal lattice.

  1. On the influence of frequency-dependent elastic properties in vibro-acoustic modelling of porous materials under structural excitation

    NASA Astrophysics Data System (ADS)

    Van der Kelen, C.; Göransson, P.; Pluymers, B.; Desmet, W.

    2014-12-01

    The aspects related to modelling the frequency dependence of the elastic properties of air-saturated porous materials have been largely neglected in the past for several reasons. For acoustic excitation of porous materials, the material behaviour can be quite well represented by models where the properties of the solid frame have little influence. Only recently has the importance of the dynamic moduli of the frame come into focus. This is related to a growing interest in the material behaviour due to structural excitation. Two aspects stand out in connection with the elastic-dynamic behaviour. The first is related to methods for the characterisation of the dynamic moduli of porous materials. The second is a perceived lack of numerical methods able to model the complex material behaviour under structural excitation, in particular at higher frequencies. In the current paper, experimental data from a panel under structural excitation, coated with a porous material, are presented. In an attempt to correlate the experimental data to numerical predictions, it is found that the measured quasi-static material parameters do not suffice for an accurate prediction of the measured results. The elastic material parameters are then estimated by correlating the numerical prediction to the experimental data, following the physical behaviour predicted by the augmented Hooke's law. The change in material behaviour due to the frequency-dependent properties is illustrated in terms of the propagation of the slow wave and the shear wave in the porous material.

  2. Acoustic tests on a new motor generator system for the minuteman launch control centers in Hill engineering test facilities 1 and 2, Hill AFB, Utah

    NASA Astrophysics Data System (ADS)

    Fairman, Terry M.

    1989-04-01

    Post critical design review acoustic tests were performed in Hill Engineering Test Facilities 1 and 2 (HETF) on a proposed new motor generator system for the Minuteman Launch Control Centers (LCC). A performance noise criteria equivalent to a preferred noise criterion (PNC-50) curve was established as the standard by which to judge the effectiveness of the new motor generator. Measurements were obtained at both the commander's console and the deputy commander's console. Results indicated the noise from the motor generator as configured in HETF 1 (the small LCC) exceeded the PNC-50 criteria primarily in the 63 hertz (Hz) octave band by 10 decibels (dB) when operated in both the ac and dc modes. The motor generator as configured in HETF 2 (the large LCC) exceeded the PNC-50 criteria by 3 dB in the 125 Hz octave band only at the deputy commander's console when operated in the ac mode. Acoustic intensity measurements were obtained to isolate specific noise sources and determine the transmission loss of the floor panels. Vibration measurements were also made on and near the motor generator to determine paths of structure-borne vibration energy. Specific recommendations for improving the acoustic environment in the LCC's are presented.

  3. High acoustic strains in Si through ultrafast laser excitation of Ti thin-film transducers.

    PubMed

    Tzianaki, Eirini; Bakarezos, Makis; Tsibidis, George D; Orphanos, Yannis; Loukakos, Panagiotis A; Kosmidis, Constantine; Patsalas, Panos; Tatarakis, Michael; Papadogiannis, Nektarios A

    2015-06-29

    The role of thin-film metal transducers in ultrafast laser-generated longitudinal acoustic phonons in Si (100) monocrystal substrates is investigated. For this purpose degenerate femtosecond pump-probe transient reflectivity measurements are performed probing the Brillouin scattering of laser photons from phonons. The influence of the metallic electron-phonon coupling factor, acoustical impedance and film thickness is examined. An optical transfer matrix method for thin films is applied to extract the net acoustic strain relative strength for the various transducer cases, taking into account the experimental probing efficiency. In addition, a theoretical thermo-mechanical approach based on the combination of a revised two-temperature model and elasticity theory is applied and supports the experimental findings. The results show highly efficient generation of acoustic phonons in Si when Ti transducers are used. This demonstrates the crucial role of the transducer's high electron-phonon coupling constant and high compressive yield strength, as well as strong acoustical impedance matching with the semiconductor substrate.

  4. Aerodynamic excitation and sound production of blown-closed free reeds without acoustic coupling: The example of the accordion reed

    NASA Astrophysics Data System (ADS)

    Ricot, Denis; Caussé, René; Misdariis, Nicolas

    2005-04-01

    The accordion reed is an example of a blown-closed free reed. Unlike most oscillating valves in wind musical instruments, self-sustained oscillations occur without acoustic coupling. Flow visualizations and measurements in water show that the flow can be supposed incompressible and potential. A model is developed and the solution is calculated in the time domain. The excitation force is found to be associated with the inertial load of the unsteady flow through the reed gaps. Inertial effect leads to velocity fluctuations in the reed opening and then to an unsteady Bernoulli force. A pressure component generated by the local reciprocal air movement around the reed is added to the modeled aerodynamic excitation pressure. Since the model is two-dimensional, only qualitative comparisons with air flow measurements are possible. The agreement between the simulated pressure waveforms and measured pressure in the very near-field of the reed is reasonable. In addition, an aeroacoustic model using the permeable Ffowcs Williams-Hawkings integral method is presented. The integral expressions of the far-field acoustic pressure are also computed in the time domain. In agreement with experimental data, the sound is found to be dominated by the dipolar source associated by the strong momentum fluctuations of the flow through the reed gaps. .

  5. On the variations of acoustic absorption peak with particle velocity in micro-perforated panels at high level of excitation.

    PubMed

    Tayong, Rostand; Dupont, Thomas; Leclaire, Philippe

    2010-05-01

    The acoustic behavior of micro-perforated panels (MPP) is studied theoretically and experimentally at high level of pressure excitation. A model based on Forchheimer's regime of flow velocity in the perforations is proposed. This model is valid at relatively high Reynolds numbers and low Mach numbers. The experimental method consists in measuring the acoustical pressure at three different positions in an impedance tube, the two measurement positions usually considered in an impedance tube and one measurement in the vicinity of the rear surface of the MPP. The impedance tube is equipped with a pressure driver instead of the usual loudspeaker and capable of delivering a high sound pressure level up to 160 dB. MPP specimens made out of steel, dural and polypropylene were tested. Measurements using random noise or sinusoidal excitation in a frequency range between 200 and 1600 Hz were carried out on MPPs backed by air cavities. It was observed that the maximum of absorption can be a positive or a negative function of the flow velocity in the perforations. This suggests the existence of a maximum of absorption as a function of flow velocity. This behavior was predicted by the model and confirmed experimentally.

  6. Influence of crystal quality on the excitation and propagation of surface and bulk acoustic waves in polycrystalline AlN films.

    PubMed

    Clement, Marta; Olivares, Jimena; Capilla, Jose; Sangrador, Jesús; Iborra, Enrique

    2012-01-01

    We investigate the excitation and propagation of acoustic waves in polycrystalline aluminum nitride films along the directions parallel and normal to the c-axis. Longitudinal and transverse propagations are assessed through the frequency response of surface acoustic wave and bulk acoustic wave devices fabricated on films of different crystal qualities. The crystalline properties significantly affect the electromechanical coupling factors and acoustic properties of the piezoelectric layers. The presence of misoriented grains produces an overall decrease of the piezoelectric activity, degrading more severely the excitation and propagation of waves traveling transversally to the c-axis. It is suggested that the presence of such crystalline defects in c-axis-oriented films reduces the mechanical coherence between grains and hinders the transverse deformation of the film when the electric field is applied parallel to the surface. © 2012 IEEE

  7. Pulsed-laser excitation of acoustic modes in open high-Q photoacoustic resonators for trace gas monitoring: results for C2H4

    NASA Astrophysics Data System (ADS)

    Brand, Christian; Winkler, Andreas; Hess, Peter; Miklós, András; Bozóki, Zoltán; Sneider, János

    1995-06-01

    The pulsed excitation of acoustic resonances was studied with a continuously monitoring photoacoustic detector system. Acoustic waves were generated in C2H4/N 2 gas mixtures by light absorption of the pulses from a transversely excited atmospheric CO2 laser. The photoacoustic part consisted of high-Q cylindrical resonators (Q factor 820 for the first radial mode in N2) and two adjoining variable acoustic filter systems. The time-resolved signal was Fourier transformed to a frequency spectrum of high resolution. For the first radial mode a Lorentzian profile was fitted to the measured data. The outside noise suppression and the signal-to-noise ratio were investigated in a normal laboratory environment in the flow-through mode. The acoustic and electric filter system combined with the

  8. Tunable repetition rate VECSEL for resonant acoustic-excitation of nanostructures

    NASA Astrophysics Data System (ADS)

    Chen Sverre, T.; Head, C. R.; Turnbull, A. P.; Shaw, E. A.; Tropper, A. C.; Muskens, O. L.

    2016-03-01

    We report a passively mode-locked InGaAs-quantum well VECSEL, emitting a constant pulse train at an average output power of 18 mW and emission wavelength of 1035 nm, with a continuously tunable pulse repetitionfrequency (PRF) between 0.88 - 1.88 GHz. Pulse duration was 230 fs over 80% of that range. Here we propose a technique making use of the demonstrated VECSEL PRF tunability for a resonant frequency-domain pumpprobe spectroscopic technique for acoustic interrogation of nanostructures. Simulation of suitable GHz acoustic resonators to demonstrate this technique is described.

  9. Influence of surface-wave excitation on efficiency of space-wave launching in microstrip disc antennas

    NASA Astrophysics Data System (ADS)

    Fonseca, S. B. De A.; Giarola, A. J.

    1982-05-01

    The cavity model with magnetic side walls and dyadic Green's functions was used to study microstip disc antennas. Curves of efficiency of space-wave launching and directivity as functions of the ratio of the dielectric thickness to the disc radius d/a are shown for two dielectrics with permittivity equal to 2.55 and 9.60. The results are useful for the design of these antennas.

  10. Acoustic wave excitation during the aerodynamic interaction between a fan blade and a bluff obstacle

    NASA Astrophysics Data System (ADS)

    Chukhlantsev, S. G.

    1990-08-01

    The forces generated by flow over the surface of a fan blade and a bluff obstacle are calculated using the discrete vortex method. The results are then used to determine the sound source and the acoustic field formed. Results of an experimental verification of the analytical relations are presented.

  11. Modeling stochastic excitation of acoustic modes in stars: present status and perspectives

    NASA Astrophysics Data System (ADS)

    Samadi, R.; Belkacem, K.; Goupil, M.-J.; Ludwig, H.-G.; Dupret, M.-A.

    2008-12-01

    Solar-like oscillations have now been detected for more than ten years and their frequencies measured for a still growing number of stars with various characteristics (e.g. mass, chemical composition, evolutionary stage ...). Excitation of such oscillations is attributed to turbu- lent convection and takes place in the uppermost part of the convective envelope. Since the pioneering work of Goldreich & Keely (1977), more sophisticated theoretical models of stochastic excitation were developed, which differ from each other both by the way turbulent convection is modeled and by the assumed sources of excitation. We briefly review here the different underlying approximations and assumptions of those models. A second part shows that computed mode excitation rates crucially depend on the way time-correlations between eddies are described but also on the surface metal abundance of the star.

  12. Time interval measurement device based on surface acoustic wave filter excitation, providing 1 ps precision and stability

    NASA Astrophysics Data System (ADS)

    Panek, Petr; Prochazka, Ivan

    2007-09-01

    This article deals with the time interval measurement device, which is based on a surface acoustic wave (SAW) filter as a time interpolator. The operating principle is based on the fact that a transversal SAW filter excited by a short pulse can generate a finite signal with highly suppressed spectra outside a narrow frequency band. If the responses to two excitations are sampled at clock ticks, they can be precisely reconstructed from a finite number of samples and then compared so as to determine the time interval between the two excitations. We have designed and constructed a two-channel time interval measurement device which allows independent timing of two events and evaluation of the time interval between them. The device has been constructed using commercially available components. The experimental results proved the concept. We have assessed the single-shot time interval measurement precision of 1.3ps rms that corresponds to the time of arrival precision of 0.9ps rms in each channel. The temperature drift of the measured time interval on temperature is lower than 0.5ps/K, and the long term stability is better than ±0.2ps/h. These are to our knowledge the best values reported for the time interval measurement device. The results are in good agreement with the error budget based on the theoretical analysis.

  13. GNSS-TEC observations of infrasound excited by a volcanic eruption: Inference of wave front geometry and acoustic wave energy

    NASA Astrophysics Data System (ADS)

    Nakashima, Y.; Aoki, Y.; Nishida, K.; Heki, K.

    2016-12-01

    Volcanic eruptions excite various oscillations depending on various factors. Very low frequency infrasound (-5 mHz) can reach the upper atmosphere and are often observed as ionospheric fluctuations. We can see three types of ionospheric disturbances excited by volcanic eruptions: (1) acoustic trap mode, (2) atmospheric internal gravity wave and (3) traveling acoustic waves come from volcanic explosion. The third one is important to improve our knowledge of acoustic energy by volcanic explosions because we cannot detect infrasound propagating upward by barometers deployed on the ground. We found ionospheric disturbances made by the Kuchinoerabujima volcano eruption on 29 May, 2015, using the GNSS-TEC method. This case is similar to the 2004 Asamayama volcano explosion, and we tried to estimate the energy of the acoustic wave. In this presentation, we will compare TEC perturbations and surface pressure changes. We use 1 Hz-sampled GEONET data from stations in Southwest Japan. Conversion from slant-TEC to vertical-TEC was done using the minimum scalloping. We used apparent velocities calculated from cross correlation function of the TEC disturbances to infer the wave front geometry. Previous studies discussed wave fronts calculated by ray-tracing. However, ray tracing may be inappropriate to such a case because it assumes very short wave length compared with the scale height. Accordingly, we estimated the incident angles from the apparent wave velocities assuming that the ionosphere is a thin layer located at 300 km above the surface. We derived incident angles, and they were similar to those we obtained by ray tracing. In addition, we found that the incident angles inferred in this way had significant dependence on azimuths. We need to find out whether it is real or an apparent phenomenon caused by stations-satellites-wave geometry. We are now trying to estimate the energy, but it varies around the estimated value for the 2004 Asama volcano case. We will consider the

  14. Observed acoustic and aeroelastic spectral responses of a MOD-2 turbine blade to turbulence excitation

    NASA Technical Reports Server (NTRS)

    Kelley, N. D.; Mckenna, H. E.; Jacobs, E. W.

    1995-01-01

    Early results from a recent experiment designed to directly evaluate the aeroacoustic/elastic spectral responses of a MOD-2 turbine blade to turbulence-induced unsteady blade loads are discussed. The experimental procedure consisted of flying a hot-film anemometer from a tethered balloon in the turbine inflow and simultaneously measuring the fluctuating airload and aeroelastic response at two blade span stations (65% and 87% spans) using surface-mounted, subminiature pressure transducers and standard strain gage instrumentation. The radiated acoustic pressure field was measured with a triad of very-low-frequency microphones placed at ground level, 1.5 rotor diameters upwind of the disk. Initial transfer function estimates for acoustic radiation, blade normal forces, flapwise acceleration/displacement, and chord/flapwise moments are presented.

  15. Excitation of Ion Acoustic Waves in Confined Plasmas with Untrapped Electrons

    NASA Astrophysics Data System (ADS)

    Schamis, Hanna; Dow, Ansel; Carlsson, Johan; Kaganovich, Igor; Khrabrov, Alexander

    2015-11-01

    Various plasma propulsion devices exhibit strong electron emission from the walls either as a result of secondary processes or due to thermionic emission. To understand the electron kinetics in plasmas with strong emission, we have performed simulations using a reduced model with the LSP particle-in-cell code. This model aims to show the instability generated by the electron emission, in the form of ion acoustic waves near the sheath. It also aims to show the instability produced by untrapped electrons that propagate across the plasma, similarly to a beam, and can drive ion acoustic waves in the plasma bulk. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No.DE-AC02-09CH11466.

  16. Electromechanical, acoustical and thermodynamical characterization of a low-frequency sonotrode-type transducer in a small sonoreactor at different excitation levels and loading conditions.

    PubMed

    Petošić, Antonio; Horvat, Marko; Režek Jambrak, Anet

    2017-11-01

    The paper reports and compares the results of the electromechanical, acoustical and thermodynamical characterization of a low-frequency sonotrode-type ultrasonic device inside a small sonoreactor, immersed in three different loading media, namely, water, juice and milk, excited at different excitation levels, both below and above the cavitation threshold. The electroacoustic efficiency factor determined at system resonance through electromechanical characterization in degassed water as the reference medium is 88.7% for the device in question. This efficiency can be reduced up to three times due to the existence of a complex sound field in the reactor in linear driving conditions below the cavitation threshold. The behaviour of the system is more stable at higher excitation levels than in linear operating conditions. During acoustical characterization, acoustic pressure is spatially averaged, both below and above the cavitation threshold. The standing wave patterns inside the sonoreactor have a stronger influence on the variation of the spatially distributed RMS pressure in linear operating conditions. For these conditions, the variation of ±1.7dB was obtained, compared to ±1.4dB obtained in highly nonlinear regime. The acoustic power in the sonoreactor was estimated from the magnitude of the averaged RMS pressure, and from the reverberation time of the sonoreactor as the representation of the losses. The electroacoustic efficiency factors obtained through acoustical and electromechanical characterization are in a very good agreement at low excitation levels. The irradiated acoustic power estimated in nonlinear conditions differs from the dissipated acoustic power determined with the calorimetric method by several orders of magnitude. The number of negative pressure peaks that represent transient cavitation decreases over time during longer treatments of a medium with high-power ultrasound. The number of negative peaks decreases faster when the medium and the

  17. Two-dimensional modulated ion-acoustic excitations in electronegative plasmas

    NASA Astrophysics Data System (ADS)

    Panguetna, Chérif S.; Tabi, Conrad B.; Kofané, Timoléon C.

    2017-09-01

    Two-dimensional modulated ion-acoustic waves are investigated in an electronegative plasma. Through the reductive perturbation expansion, the governing hydrodynamic equations are reduced to a Davey-Stewartson system with two-space variables. The latter is used to study the modulational instability of ion-acoustic waves along with the effect of plasma parameters, namely, the negative ion concentration ratio (α) and the electron-to-negative ion temperature ratio (σn). A parametric analysis of modulational instability is carried out, where regions of plasma parameters responsible for the emergence of modulated ion-acoustic waves are discussed, with emphasis on the behavior of the instability growth rate. Numerically, using perturbed plane waves as initial conditions, parameters from the instability regions give rise to series of dromion solitons under the activation of modulational instability. The sensitivity of the numerical solutions to plasma parameters is discussed. Some exact solutions in the form one- and two-dromion solutions are derived and their response to the effect of varying α and σn is discussed as well.

  18. Optical Quantification of Harmonic Acoustic Radiation Force Excitation in a Tissue-Mimicking Phantom.

    PubMed

    Suomi, Visa; Edwards, David; Cleveland, Robin

    2015-12-01

    Optical tracking was used to characterize acoustic radiation force-induced displacements in a tissue-mimicking phantom. Amplitude-modulated 3.3-MHz ultrasound was used to induce acoustic radiation force in the phantom, which was embedded with 10-μm microspheres that were tracked using a microscope objective and high-speed camera. For sine and square amplitude modulation, the harmonic components of the fundamental and second and third harmonic frequencies were measured. The displacement amplitudes were found to increase linearly with acoustic radiation force up to 10 μm, with sine modulation having 19.5% lower peak-to-peak amplitude values than square modulation. Square modulation produced almost no second harmonic, but energy was present in the third harmonic. For the sine modulation, energy was present in the second harmonic and low energy in the third harmonic. A finite-element model was used to simulate the deformation and was both qualitatively and quantitatively in agreement with the measurements. Copyright © 2015 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

  19. Modulational excitation of low-frequency dust acoustic waves in the Earth's lower ionosphere

    SciTech Connect

    Kopnin, S. I.; Popel, S. I.; Yu, M. Y.

    2007-04-15

    During the observation of Perseid, Leonid, Gemenid, and Orionid meteor showers, stable low-frequency lines in the frequency range of 20-60 Hz were recorded against the radio-frequency noise background. A physical mechanism for this effect is proposed, and it is established that the effect itself is related to the modulational interaction between electromagnetic and dust acoustic waves. The dynamics of the components of a complex (dusty) ionospheric plasma with dust produced from the evolution of meteoric material is described. The conditions for the existence of dust acoustic waves in the ionosphere are considered, and the waves are shown to dissipate energy mainly in collisions of neutral particles with charged dust grains. The modulational instability of electromagnetic waves in a complex (dusty) ionospheric plasma is analyzed and is found to be driven by the nonlinear Joule heating, the ponderomotive force, and the processes governing dust charging and dynamics. The conditions for the onset of the modulational instability of electromagnetic waves, as well as its growth rate and threshold, are determined for both daytime and nighttime. It is shown that low-frequency perturbations generated in the modulational interaction are related to dust acoustic waves.

  20. Development of modified vibration test criteria for qualifying space vehicle components. [subjected to broadband random acoustic excitation

    NASA Technical Reports Server (NTRS)

    Chang, K. Y.; Kao, G. C.

    1974-01-01

    Simplified methods are described to estimate the test criteria of primary structures at component attachment points subjected to broadband random acoustic excitations. The current method utilizes a constant smeared component mass attenuation factor across the frequency range of interest. The developed method indicates that the attenuation factor is based on a frequency dependent ratio of the mechanical impedances of both the component and primary structures. The procedures used to predict the structural responses are considered as the present state-of-the-art and provide satisfactory prediction results. Example problems are used to illustrate the application procedures of the two methods and to compare the significant difference. It was found that the lower test criteria obtained by the impedance ratio method is due to the results of considering the effects of component/primary structure interaction.

  1. Acoustics

    NASA Technical Reports Server (NTRS)

    Goodman, Jerry R.; Grosveld, Ferdinand

    2007-01-01

    The acoustics environment in space operations is important to maintain at manageable levels so that the crewperson can remain safe, functional, effective, and reasonably comfortable. High acoustic levels can produce temporary or permanent hearing loss, or cause other physiological symptoms such as auditory pain, headaches, discomfort, strain in the vocal cords, or fatigue. Noise is defined as undesirable sound. Excessive noise may result in psychological effects such as irritability, inability to concentrate, decrease in productivity, annoyance, errors in judgment, and distraction. A noisy environment can also result in the inability to sleep, or sleep well. Elevated noise levels can affect the ability to communicate, understand what is being said, hear what is going on in the environment, degrade crew performance and operations, and create habitability concerns. Superfluous noise emissions can also create the inability to hear alarms or other important auditory cues such as an equipment malfunctioning. Recent space flight experience, evaluations of the requirements in crew habitable areas, and lessons learned (Goodman 2003; Allen and Goodman 2003; Pilkinton 2003; Grosveld et al. 2003) show the importance of maintaining an acceptable acoustics environment. This is best accomplished by having a high-quality set of limits/requirements early in the program, the "designing in" of acoustics in the development of hardware and systems, and by monitoring, testing and verifying the levels to ensure that they are acceptable.

  2. Computed Linear/Nonlinear Acoustic Response of a Cascade for Single/Multi Frequency Excitation

    NASA Technical Reports Server (NTRS)

    Nallasamy, M.; Hixon, R.; Sawyer, S.

    2004-01-01

    This paper examines mode generation and propagation characteristics of a 2-D cascade due to incident vortical disturbances using a time domain approach. Full nonlinear Euler equations are solved employing high order accurate spatial differencing and time marching techniques. The solutions show the generation and propagation of mode orders that are expected from theory. Single frequency excitations show linear response over a wide range of amplitudes. The response for multi-frequency excitations tend to become nonlinear due to interaction between frequencies and self interaction.

  3. Line-Focused Optical Excitation of Parallel Acoustic Focused Sample Streams for High Volumetric and Analytical Rate Flow Cytometry.

    PubMed

    Kalb, Daniel M; Fencl, Frank A; Woods, Travis A; Swanson, August; Maestas, Gian C; Juárez, Jaime J; Edwards, Bruce S; Shreve, Andrew P; Graves, Steven W

    2017-09-19

    Flow cytometry provides highly sensitive multiparameter analysis of cells and particles but has been largely limited to the use of a single focused sample stream. This limits the analytical rate to ∼50K particles/s and the volumetric rate to ∼250 μL/min. Despite the analytical prowess of flow cytometry, there are applications where these rates are insufficient, such as rare cell analysis in high cellular backgrounds (e.g., circulating tumor cells and fetal cells in maternal blood), detection of cells/particles in large dilute samples (e.g., water quality, urine analysis), or high-throughput screening applications. Here we report a highly parallel acoustic flow cytometer that uses an acoustic standing wave to focus particles into 16 parallel analysis points across a 2.3 mm wide optical flow cell. A line-focused laser and wide-field collection optics are used to excite and collect the fluorescence emission of these parallel streams onto a high-speed camera for analysis. With this instrument format and fluorescent microsphere standards, we obtain analysis rates of 100K/s and flow rates of 10 mL/min, while maintaining optical performance comparable to that of a commercial flow cytometer. The results with our initial prototype instrument demonstrate that the integration of key parallelizable components, including the line-focused laser, particle focusing using multinode acoustic standing waves, and a spatially arrayed detector, can increase analytical and volumetric throughputs by orders of magnitude in a compact, simple, and cost-effective platform. Such instruments will be of great value to applications in need of high-throughput yet sensitive flow cytometry analysis.

  4. Surface Optomechanics: Calculating Optically Excited Acoustical Whispering Gallery Modes in Microspheres

    DTIC Science & Technology

    2011-07-18

    Spillane, and K. J. Vahala, “ Erbium - doped and Raman microlasers on a silicon chip fabricated by the sol-gel process,” Appl. Phys. Lett. 86(9), 091114 (2005...these acoustic whispering gallery modes is widely used in on- chip microdevices [2,3] to allow Raman- [4] and Erbium - [5] lasers , parametric...Ultralow-threshold Raman laser using a spherical dielectric microcavity,” Nature 415(6872), 621–623 (2002). 5. L. Yang, T. Carmon, B. Min, S. M

  5. Nonlinear excitations for the positron acoustic waves in auroral acceleration regions

    NASA Astrophysics Data System (ADS)

    Saha, Asit; Ali, Rustam; Chatterjee, Prasanta

    2017-09-01

    Positron acoustic waves (PAWs) in an unmagnetized electron-positron-ion (e-p-i) plasma consisting of mobile cold positrons, immobile positive ions, q-nonextensive distributed electrons and hot positrons are studied. The standard reductive perturbation technique (RPT) is applied to derive the Kurteweg-de Vries (KdV) and modified Kurteweg-de Vries (mKdV) equations for PAWs. Variations of the total energy of the conservative systems corresponding to the KdV and mKdV equations are presented. Using numerical simulations, effect of the nonextensive parameter (q), temperature ratio (σ) of electrons to hot positrons and speed (U) of the traveling wave are discussed on the positron acoustic solitary wave solutions of the KdV and mKdV equations. Considering an external periodic perturbation, the perturbed dynamical systems corresponding to the KdV and mKdV equations are analyzed by employing phase orbit analysis, Poincare section and Lyapunov exponent. The frequency (ω) of the external periodic perturbation plays the role of the switching parameter in chaotic motions of the perturbed PAWs through quasiperiodic route to chaos. This work may be useful to understand the qualitative changes in the dynamics of nonlinear perturbations in auroral acceleration regions.

  6. Hypersonic acoustic excitations in binary colloidal crystals: big versus small hard sphere control.

    PubMed

    Tommaseo, G; Petekidis, G; Steffen, W; Fytas, G; Schofield, A B; Stefanou, N

    2007-01-07

    The phononic band structure of two binary colloidal crystals, at hypersonic frequencies, is studied by means of Brillouin light scattering and analyzed in conjunction with corresponding dispersion diagrams of the single colloidal crystals of the constituent particles. Besides the acoustic band of the average medium, the authors' results show the existence of narrow bands originating from resonant multipole modes of the individual particles as well as Bragg-type modes due to the (short-range) periodicity. Strong interaction, leading to the occurrence of hybridization gaps, is observed between the acoustic band and the band of quadrupole modes of the particles that occupy the largest fractional volume of the mixed crystal; the effective radius is either that of the large (in the symmetric NaCl-type crystalline phase) or the small (in the asymmetric NaZn(13)-type crystalline phase) particles. The possibility to reveal a universal behavior of the phononic band structure for different single and binary colloidal crystalline suspensions, by representing in the dispersion diagrams reduced quantities using an appropriate length scale, is discussed.

  7. Nonlinear excitations for the positron acoustic shock waves in dissipative nonextensive electron-positron-ion plasmas

    NASA Astrophysics Data System (ADS)

    Saha, Asit

    2017-03-01

    Positron acoustic shock waves (PASHWs) in unmagnetized electron-positron-ion (e-p-i) plasmas consisting of mobile cold positrons, immobile positive ions, q-nonextensive distributed electrons, and hot positrons are studied. The cold positron kinematic viscosity is considered and the reductive perturbation technique is used to derive the Burgers equation. Applying traveling wave transformation, the Burgers equation is transformed to a one dimensional dynamical system. All possible vector fields corresponding to the dynamical system are presented. We have analyzed the dynamical system with the help of potential energy, which helps to identify the stability and instability of the equilibrium points. It is found that the viscous force acting on cold mobile positron fluid is a source of dissipation and is responsible for the formation of the PASHWs. Furthermore, fully nonlinear arbitrary amplitude positron acoustic waves are also studied applying the theory of planar dynamical systems. It is also observed that the fundamental features of the small amplitude and arbitrary amplitude PASHWs are significantly affected by the effect of the physical parameters q e , q h , μ e , μ h , σ , η , and U. This work can be useful to understand the qualitative changes in the dynamics of nonlinear small amplitude and fully nonlinear arbitrary amplitude PASHWs in solar wind, ionosphere, lower part of magnetosphere, and auroral acceleration regions.

  8. Picosecond x-ray strain rosette reveals direct laser excitation of coherent transverse acoustic phonons

    DOE PAGES

    Lee, Sooheyong; Williams, G. Jackson; Campana, Maria I.; ...

    2016-01-11

    Using a strain-rosette, we demonstrate the existence of transverse strain using time-resolved x-ray diffraction from multiple Bragg reflections in laser-excited bulk gallium arsenide. We find that anisotropic strain is responsible for a considerable fraction of the total lattice motion at early times before thermal equilibrium is achieved. Our measurements are described by a new model where the Poisson ratio drives transverse motion, resulting in the creation of shear waves without the need for an indirect process such as mode conversion at an interface. Finally, using the same excitation geometry with the narrow-gap semiconductor indium antimonide, we detected coherent transverse acousticmore » oscillations at frequencies of several GHz.« less

  9. Acoustical Radiation from Periodically Stiffened Membrane Excited by Turbulent Boundary Layer.

    DTIC Science & Technology

    1975-04-01

    on the vibratory response of thi~n plates or membranes to a turbulent boundary layer pres- sure excitation and the subsequent radiation of sound by...these plates or membranes. In the previous work, studies have included only the response of, or radiation from, simple structures. Actual structures may...be a complex system of plates forming a skin over a rib-like structure of beams. In one limit, very rigid beamus divide the skin into a number of

  10. NEW APPLICATIONS IN THE INVERSION OF ACOUSTIC FULL WAVEFORM LOGS - RELATING MODE EXCITATION TO LITHOLOGY.

    USGS Publications Warehouse

    Paillet, Frederick L.; Cheng, C.H.; Meredith, J.A.

    1987-01-01

    Existing techniques for the quantitative interpretation of waveform data have been based on one of two fundamental approaches: (1) simultaneous identification of compressional and shear velocities; and (2) least-squares minimization of the difference between experimental waveforms and synthetic seismograms. Techniques based on the first approach do not always work, and those based on the second seem too numerically cumbersome for routine application during data processing. An alternative approach is tested here, in which synthetic waveforms are used to predict relative mode excitation in the composite waveform. Synthetic waveforms are generated for a series of lithologies ranging from hard, crystalline rocks (Vp equals 6. 0 km/sec. and Poisson's ratio equals 0. 20) to soft, argillaceous sediments (Vp equals 1. 8 km/sec. and Poisson's ratio equals 0. 40). The series of waveforms illustrates a continuous change within this range of rock properties. Mode energy within characteristic velocity windows is computed for each of the modes in the set of synthetic waveforms. The results indicate that there is a consistent variation in mode excitation in lithology space that can be used to construct a unique relationship between relative mode excitation and lithology.

  11. Modal analysis and dynamic stresses for acoustically excited shuttle insulation tiles

    NASA Technical Reports Server (NTRS)

    Ojalvo, I. U.; Ogilvie, P. L.

    1975-01-01

    Improvements and extensions to the RESIST computer program developed for determining the normalized modal stress response of shuttle insulation tiles are described. The new version of RESIST can accommodate primary structure panels with closed-cell stringers, in addition to the capability for treating open-cell stringers. In addition, the present version of RESIST numerically solves vibration problems several times faster than its predecessor. A new digital computer program, titled ARREST (Acoustic Response of Reusable Shuttle Tiles) is also described. Starting with modal information contained on output tapes from RESIST computer runs, ARREST determines RMS stresses, deflections and accelerations of shuttle panels with reusable surface insulation tiles. Both programs are applicable to stringer stiffened structural panels with or without reusable surface insulation titles.

  12. Dust-acoustic shock excitations in κ-nonthermal electron depleted dusty plasmas

    NASA Astrophysics Data System (ADS)

    Ferdousi, Mariya; Sultana, Sharmin; Hossen, Mohammad Mobarak; Rashed Miah, Md.; Mamun, A. A.

    2017-04-01

    A theoretical investigation on the characteristics of dust-acoustic shock waves (DASHWs) in an unmagnetized multi-ion dusty plasma has been made both theoretically and analytically. The plasma medium is assumed to compose of arbitrarily charged inertial dusts, Boltzmann distributed negatively charged heavy ions, positively charged light ions, and superthermal (excess energetic) electrons (where superthermality is modelled via the κ-distribution). The reductive perturbation technique is employed in order to derive the nonlinear time evolution Burgers type equation. The basic properties of DASHWs are analysed via the solution of Burgers equation. It is observed that different plasma parameters (electrons superthermality, dust temperature, ion temperature, dust kinematic viscosity, etc.) influence the propagation of DASHWs. Both polarity (positive and negative potential) shock waves are also found to exists. The study of our model under consideration is helpful for explaining the propagation of DASHWs in space observations, where superthermal electrons and Maxwellian ions are accountable.

  13. Pressure probe and hot-film probe rsponses to acoustic excitation in mean flow

    NASA Technical Reports Server (NTRS)

    Parrott, T. L.; Jones, M. G.

    1986-01-01

    An experiment was conducted to compare the relative responses of a hot-film probe and a pressure probe positioned in a flow duct carrying mean flow and progressive acoustic waves. The response of each probe was compared with that of a condenser-type microphone flush mounted in the duct wall for flow Mach numbers up to about 0.5. The response of the pressure probe was less than that of the flush-mounted microphone by not more than about 2.1 dB at the highest centerline Mach number. This decreased response of the probe can likely be attributed to flow-induced impedance changes at the probe sensor orifices. The response of the hot-film probe, expressed in terms of fluctuating pressure, was greater than that of the flush-mounted microphone by as much as 6.0 dB at the two higher centerline Mach numbers. Removal of the contribution from fluctuating temperature in the hot-film analytical model greatly improved the agreement between the two transducer responses.

  14. Coherent structure interactions in a two-stream plane turbulent mixing layer with impulsive acoustic excitation

    NASA Astrophysics Data System (ADS)

    Latigo, Ben O.

    1989-10-01

    Periodic plane acoustic waves consisting of four discrete pulses are used to trigger the Kelvin-Helmholtz (KH) instability at the origin of an initially laminar plane mixing layer. The resulting coherent large-scale structures (CLSS) which grow and interact with their neighbors are followed downstream with hot-wire probes traversed across the mixing layer to a Reynolds number Re=1.5×106. The Reynolds number here is based on downstream distance x and the velocity difference (U1-U2). The continuous hot-wire time record is conditionally sampled with respect to the tone bursts and the samples are phase averaged to reveal the CLSS footprints. Optimum phase averages are obtained using an iterative correlation technique that corrects for phase jitters due to turbulence. An enhanced study of the CLSS is therefore made possible. The ensembles reveal a vivid picture of vortex pairing between the initial eddies as well as the significant role played by the CLSS in momentum transport; hence turbulence mixing.

  15. Coherent structure interactions in a two-stream plane turbulent mixing layer with impulsive acoustic excitation

    NASA Astrophysics Data System (ADS)

    Latigo, Ben O.

    1989-10-01

    Periodic plane acoustic waves consisting of four discrete pulses are used to trigger the Kelvin-Helmholtz (KH) instability at the origin of an initially laminar plane mixing layer. The resulting coherent large-scale structures (CLSS), which grow and interact with their neighbors, are followed downstream with hot-wire probes traversed across the mixing layer to a Reynolds number Re = 1.5 x 10 to the 6th. The Reynolds number here is based on downstream distance x and the velocity difference (U1-U2). The continuous hot-wire time record is conditionally sampled with respect to the tone bursts and the samples are phase averaged to reveal the CLSS footprints. Optimum phase averages are obtained using an iterative correlation technique that corrects for phase jitters due to turbulence. An enhanced study of the CLSS is therefore made possible. The ensembles reveal a vivid picture of vortex pairing between the initial eddies as well as the significant role played by the CLSS in momentum transport; hence turbulence mixing.

  16. Arbitrary amplitude ion-acoustic solitary excitations in the presence of excess superthermal electrons

    SciTech Connect

    Saini, N. S.; Kourakis, I.; Hellberg, M. A.

    2009-06-15

    Velocity distribution functions with an excess of superthermal particles are commonly observed in space plasmas, and are effectively modeled by a kappa distribution. They are also found in some laboratory experiments. In this paper we obtain existence conditions for and some characteristics of ion-acoustic solitary waves in a plasma composed of cold ions and {kappa}-distributed electrons, where {kappa}>3/2 represents the spectral index. As is the case for the usual Maxwell-Boltzmann electrons, only positive potential solitons are found, and, as expected, in the limit of large {kappa} one recovers the usual range of possible soliton Mach numbers, viz., 1

  17. Nonlinear propagation acoustics of dual-frequency wide-band excitation pulses in a focused ultrasound system.

    PubMed

    Måsøy, Svein-Erik; Standal, Øyvind; Deibele, Jochen M; Näsholm, Sven Peter; Angelsen, Bjørn; Johansen, Tonni F; Tangen, Thor Andreas; Hansen, Rune

    2010-11-01

    In this article, acoustic propagation effects of dual-frequency wide-band excitation pulses in a focused ultrasound system are demonstrated in vitro. A designed and manufactured dual-frequency band annular array capable of transmitting 0.9/7.5 MHz center frequency wide-band pulses was used for this purpose. The dual-frequency band annular array, has been designed using a bi-layer piezo-electric stack. Water tank measurements demonstrate the function of the array by activating the low- and high-frequency layers individually and simultaneously. The results show that the array works as intended. Activating the low- and high-frequency layers individually, results in less than -50 dB signal level from the high- and low-frequency layers respectively. Activating both layers simultaneously, produce a well defined dual-frequency pulse. The presence of the low-frequency pulse leads to compression, expansion, and a time delay of the high-frequency pulse. There is a phase shift between the low- and high-frequency pulse as it propagates from the array to the focus. This makes the latter described effects also dependent on the array configuration. By varying the low-frequency pressure, a shift of up to 0.5 MHz in center frequency of a 8.0 MHz transmitted high-frequency pulse is observed at the array focus. The results demonstrate the high propagation complexity of dual-frequency pulses.

  18. Wave-particle dynamics of waveform and defect evolutions in undulated nonlinear self-excited dust acoustic waves

    SciTech Connect

    Tsai, Jun-Yi; Tsai, Ya-Yi; I, Lin

    2015-01-15

    The wave-particle dynamics for the evolutions of defects and surrounding pitchfork type waveforms of a weakly disordered self-excited dust acoustic wave is experimentally investigated in an rf dusty plasma system. Particle trajectories are tracked and correlated with waveform evolution to construct an Eulerian-Lagrangian wave-particle dynamical picture. It is found that the local accumulation and depletion of particles in the wave crest and rear, respectively, determines the local crest speed, and the growth and decay of the local crest height, which in turn determine the waveform evolution. The local crest height and the focusing and defocusing of particle trajectories due to the transverse force fields from the tilted wave crest and the non-uniform crest height along the wave crest are the key factors to determine the above particle accumulation and depletion. It explains the observations such as the lower speed of smaller crests, the straightening of the leading front of the pitchfork waveform associated with the transverse motion of defect to the open side, and the vertical defect gliding in the wave frame through the detachment of the strongly kinked pitchfork branch followed by its reconnection with the trailing crest.

  19. Unsteady hydrodynamics of blade forces and acoustic responses of a model scaled submarine excited by propeller's thrust and side-forces

    NASA Astrophysics Data System (ADS)

    Wei, Yingsan; Wang, Yongsheng

    2013-04-01

    This study presents the unsteady hydrodynamics of the excitations from a 5-bladed propeller at two rotating speeds running in the wake of a small-scaled submarine and the behavior of the submarine's structure and acoustic responses under the propeller excitations. Firstly, the propeller flow and submarine flows are independently validated. The propulsion of the hull-propeller is simulated using computational fluid dynamics (CFD), so as to obtain the transient responses of the propeller excitations. Finally, the structure and acoustic responses of the submarine under propeller excitations are predicted using a finite element/boundary element model in the frequency domain. Results show that (1) the propeller excitations are tonal at the propeller harmonics, and the propeller transversal force is bigger than vertical force. (2) The structure and acoustic responses of the submarine hull is tonal mainly at the propeller harmonics and the resonant mode frequencies of the hull, and the breathing mode in axial direction as well as the bending modes in vertical and transversal directions of the hull can generate strong structure vibration and underwater noise. (3) The maximum sound pressure of the field points increases with the increasing propeller rotating speed at structure resonances and propeller harmonics, and the rudders resonant mode also contributes a lot to the sound radiation. Lastly, the critical rotating speeds of the submarine propeller are determined, which should be carefully taken into consideration when match the propeller with prime mover in the propulsion system. This work shows the importance of the propeller's tonal excitation and the breathing mode plus the bending modes in evaluating submarine's noise radiation.

  20. Current-driven ion-acoustic and potential-relaxation instabilities excited in plasma plume during electron beam welding

    SciTech Connect

    Trushnikov, D. N.; Mladenov, G. M. Koleva, E. G.; Belenkiy, V. Ya. Varushkin, S. V.

    2014-04-15

    Many papers have sought correlations between the parameters of secondary particles generated above the beam/work piece interaction zone, dynamics of processes in the keyhole, and technological processes. Low- and high-frequency oscillations of the current, collected by plasma have been observed above the welding zone during electron beam welding. Low-frequency oscillations of secondary signals are related to capillary instabilities of the keyhole, however; the physical mechanisms responsible for the high-frequency oscillations (>10 kHz) of the collected current are not fully understood. This paper shows that peak frequencies in the spectra of the collected high-frequency signal are dependent on the reciprocal distance between the welding zone and collector electrode. From the relationship between current harmonics frequency and distance of the collector/welding zone, it can be estimated that the draft velocity of electrons or phase velocity of excited waves is about 1600 m/s. The dispersion relation with the properties of ion-acoustic waves is related to electron temperature 10 000 K, ion temperature 2 400 K and plasma density 10{sup 16} m{sup −3}, which is analogues to the parameters of potential-relaxation instabilities, observed in similar conditions. The estimated critical density of the transported current for creating the anomalous resistance state of plasma is of the order of 3 A·m{sup −2}, i.e. 8 mA for a 3–10 cm{sup 2} collector electrode. Thus, it is assumed that the observed high-frequency oscillations of the current collected by the positive collector electrode are caused by relaxation processes in the plasma plume above the welding zone, and not a direct demonstration of oscillations in the keyhole.

  1. Double-mode lateral-field-excitation bulk acoustic wave characteristics of Ca3TaGa3Si2O14 crystals.

    PubMed

    Ma, Tingfeng; Zhang, Qiong; Yu, Fapeng; Xie, Chao; Wang, Ji; Du, Jianke; Huang, Bin; Huang, Jiahan; Zhang, Chao

    2017-08-01

    The double-mode lateral-field-excitation (LFE) bulk acoustic wave characteristics of Ca3TaGa3Si2O14 (CTGS) crystals are investigated. It is found that LFE devices based on (yxl)-57° CTGS crystals can work on both pure-LFE and pseudo-LFE modes when the driving electric field direction is normal to the crystallographic x axis of the piezoelectric substrate. Several double-mode LFE bulk acoustic wave devices based on CTGS crystals are designed and tested. The experimental results conform to the theoretical prediction well. Being able to operate in pure-LFE and pseudo-LFE modes, the double-mode LFE sensors show high sensitivity to both mechanical and electrical property changes of analytes. The results provide the crystal cut for double-mode LFE sensors, which is a critical basis of designing high-performance chemical and biological sensors by using double-mode LFE devices.

  2. Communication: High-frequency acoustic excitations and boson peak in glasses: A study of their temperature dependence

    NASA Astrophysics Data System (ADS)

    Ruta, B.; Baldi, G.; Giordano, V. M.; Orsingher, L.; Rols, S.; Scarponi, F.; Monaco, G.

    2010-07-01

    The results of a combined experimental study of the high-frequency acoustic dynamics and of the vibrational density of states (VDOS) as a function of temperature in a glass of sorbitol are reported here. The excess in the VDOS at ˜4.5 meV over the Debye, elastic continuum prediction (boson peak) is found to be clearly related to anomalies observed in the acoustic dispersion curve in the mesoscopic wavenumber range of few nm-1. The quasiharmonic temperature dependence of the acoustic dispersion curves offers a natural explanation for the observed scaling of the boson peak with the elastic medium properties.

  3. Experimental investigation on dynamic response of aircraft panels excited by high-intensity acoustic loads in thermal environment

    NASA Astrophysics Data System (ADS)

    WU, Z. Q.; LI, H. B.; ZHANG, W.; CHENG, H.; KONG, F. J.; LIU, B. R.

    2016-09-01

    Metallic and composite panels are the major components for thermal protection system of aircraft vehicles, which are exposed to a severe combination of aerodynamic, thermal and acoustic environments during hypersonic flights. A thermal-acoustic testing apparatus which simulates thermal and acoustic loads was used to validate the integrity and the reliability of these panels. Metallic and ceramic matrix composite flat panels were designed. Dynamic response tests of these panels were carried out using the thermal acoustic apparatus. The temperature of the metallic specimen was up to 400 °C, and the temperature of the composite specimen was up to 600 °C. Moreover, the acoustic load was over 160 dB. Acceleration responses of these testing panels were measured using high temperature instruments during the testing process. Results show that the acceleration root mean square values are dominated by sound pressure level of acoustic loads. Compared with testing data in room environment, the peaks of the acceleration dynamic response shifts obviously to the high frequency in thermal environment.

  4. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, B.T.; Chou, C.H.

    1990-03-20

    A shear acoustic transducer-lens system is described in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens. 9 figs.

  5. Acoustic transducer for acoustic microscopy

    DOEpatents

    Khuri-Yakub, Butrus T.; Chou, Ching H.

    1990-01-01

    A shear acoustic transducer-lens system in which a shear polarized piezoelectric material excites shear polarized waves at one end of a buffer rod having a lens at the other end which excites longitudinal waves in a coupling medium by mode conversion at selected locations on the lens.

  6. Effect of Coversheet Materials on the Acoustic Performance of Melamine Foam

    NASA Technical Reports Server (NTRS)

    McNelis, Anne M.; Hughes, William O.

    2015-01-01

    Melamine foam is a highly absorptive material that is often used inside the payload fairing walls of a launch vehicle. This foam reduces the acoustic excitation environment that the spacecraft experiences during launch. Often, the melamine foam is enclosed by thin coversheet materials for contamination protection, thermal protection, and electrostatic discharge control. Previous limited acoustic testing by NASA Glenn Research Center has shown that the presence of a coversheet material on the melamine foam can have a significant impact on the absorption coefficient and the transmission loss. As a result of this preliminary finding a more extensive acoustic test program using several different coversheet materials on melamine foam was performed. Those test results are summarized in this paper. Additionally, a method is provided to use the acoustic absorption and transmission loss data obtained from panel level testing to predict their combined effect for the noise reduction of a launch vehicle payload fairing.

  7. Program Computes Sound Pressures at Rocket Launches

    NASA Technical Reports Server (NTRS)

    Ogg, Gary; Heyman, Roy; White, Michael; Edquist, Karl

    2005-01-01

    Launch Vehicle External Sound Pressure is a computer program that predicts the ignition overpressure and the acoustic pressure on the surfaces and in the vicinity of a rocket and launch pad during launch. The program generates a graphical user interface (GUI) that gathers input data from the user. These data include the critical dimensions of the rocket and of any launch-pad structures that may act as acoustic reflectors, the size and shape of the exhaust duct or flame deflector, and geometrical and operational parameters of the rocket engine. For the ignition-overpressure calculations, histories of the chamber pressure and mass flow rate also are required. Once the GUI has gathered the input data, it feeds them to ignition-overpressure and launch-acoustics routines, which are based on several approximate mathematical models of distributed sources, transmission, and reflection of acoustic waves. The output of the program includes ignition overpressures and acoustic pressures at specified locations.

  8. ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS: Cellular Automaton Simulations for Target Waves in Excitable Media

    NASA Astrophysics Data System (ADS)

    Zhang, Li-Sheng; Deng, Min-Yi; Kong, Ling-Jiang; Liu, Mu-Ren; Tang, Guo-Ning

    2010-01-01

    Using the Greenberg-Hasting cellular automata model, we study the properties of target waves in excitable media under the no-flux boundary conditions. For the system has only one excited state, the computer simulation and analysis lead to the conclusions that, the number of refractory states does not influence the wave-front speed; the wave-front speed decreases as the excitation threshold increases and increases as the neighbor radius increases; the period of target waves is equal to the number of cell states; the excitation condition for target waves is that the wave-front speed must be bigger than half of the neighbor radius.

  9. Development of Magnetically Excited Flexural Plate Wave Devices for Implementation as Physical, Chemical, and Acoustic Sensors, and as Integrated Micro-Pumps for Sensored Systems

    NASA Astrophysics Data System (ADS)

    Schubert, W. K.; Mitchell, M. A.; Graf, D. C.; Shul, R. J.

    2002-05-01

    The magnetically excited flexural plate wave (mag-FPW) device has great promise as a versatile sensor platform. FPW's can have better sensitivity at lower operating frequencies than surface acoustic wave (SAW) devices. Lower operating frequency simplifies the control electronics and makes integration of sensor with electronics easier. Magnetic rather than piezoelectric excitation of the FPW greatly simplifies the device structure and processing by eliminating the need for piezoelectric thin films, also simplifying integration issues. The versatile mag-FPW resonator structure can potentially be configured to fulfill a number of critical functions in an autonomous sensored system. As a physical sensor, the device can be extremely sensitive to temperature, fluid flow, strain, acceleration and vibration. By coating the membrane with self-assembled monolayers (SAMs), or polymer films with selective absorption properties (originally developed for SAW sensors), the mass sensitivity of the FPW allows it to be used as biological or chemical sensors. Yet another critical need in autonomous sensor systems is the ability to pump fluid. FPW structures can be configured as micro-pumps. This report describes work done to develop mag-FPW devices as physical, chemical, and acoustic sensors, and as micro-pumps for both liquid and gas-phase analytes to enable new integrated sensing platform.

  10. Targeted energy transfers and passive acoustic wave redirection in a two-dimensional granular network under periodic excitation

    NASA Astrophysics Data System (ADS)

    Zhang, Yijing; Moore, Keegan J.; McFarland, D. Michael; Vakakis, Alexander F.

    2015-12-01

    We study passive pulse redirection and nonlinear targeted energy transfer in a granular network composed of two semi-infinite, ordered homogeneous granular chains mounted on linear elastic foundations and coupled by weak linear stiffnesses. Periodic excitation in the form of repetitive half-sine pulses is applied to one of the chains, designated as the "excited chain," whereas the other chain is initially at rest and is regarded as the "absorbing chain." We show that passive pulse redirection and targeted energy transfer from the excited to the absorbing chain can be achieved by macro-scale realization of the spatial analog of the Landau-Zener quantum tunneling effect. This is realized by finite stratification of the elastic foundation of the excited chain and depends on the system parameters (e.g., the percentage of stratification) and on the parameters of the periodic excitation. Utilizing empirical mode decomposition and numerical Hilbert transforms, we detect the existence of two distinct nonlinear phenomena in the periodically forced network; namely, (i) energy localization in the absorbing chain due to sustained 1:1 resonance capture leading to irreversible pulse redirection from the excited chain, and (ii) continuous energy exchanges in the form of nonlinear beats between the two chains in the absence of resonance capture. Our results extend previous findings of transient passive energy redirection in impulsively excited granular networks and demonstrate that steady state passive pulse redirection in these networks can be robustly achieved under periodic excitation.

  11. Targeted energy transfers and passive acoustic wave redirection in a two-dimensional granular network under periodic excitation

    SciTech Connect

    Zhang, Yijing Moore, Keegan J.; Vakakis, Alexander F.; McFarland, D. Michael

    2015-12-21

    We study passive pulse redirection and nonlinear targeted energy transfer in a granular network composed of two semi-infinite, ordered homogeneous granular chains mounted on linear elastic foundations and coupled by weak linear stiffnesses. Periodic excitation in the form of repetitive half-sine pulses is applied to one of the chains, designated as the “excited chain,” whereas the other chain is initially at rest and is regarded as the “absorbing chain.” We show that passive pulse redirection and targeted energy transfer from the excited to the absorbing chain can be achieved by macro-scale realization of the spatial analog of the Landau-Zener quantum tunneling effect. This is realized by finite stratification of the elastic foundation of the excited chain and depends on the system parameters (e.g., the percentage of stratification) and on the parameters of the periodic excitation. Utilizing empirical mode decomposition and numerical Hilbert transforms, we detect the existence of two distinct nonlinear phenomena in the periodically forced network; namely, (i) energy localization in the absorbing chain due to sustained 1:1 resonance capture leading to irreversible pulse redirection from the excited chain, and (ii) continuous energy exchanges in the form of nonlinear beats between the two chains in the absence of resonance capture. Our results extend previous findings of transient passive energy redirection in impulsively excited granular networks and demonstrate that steady state passive pulse redirection in these networks can be robustly achieved under periodic excitation.

  12. Pegasus air-launched space booster

    NASA Astrophysics Data System (ADS)

    Lindberg, Robert E.; Mosier, Marty R.

    The launching of small satellites with the mother- aircraft-launched Pegasus booster yields substantial cost improvements over ground launching and enhances operational flexibility, since it allows launches to be conducted into any orbital inclination. The Pegasus launch vehicle is a three-stage solid-rocket-propelled system with delta-winged first stage. The major components of airborne support equipment, located on the mother aircraft, encompass a launch panel operator console, an electronic pallet, and a pylon adapter. Alternatives to the currently employed B-52 launch platform aircraft have been identified for future use. Attention is given to the dynamic, thermal, and acoustic environments experienced by the payload.

  13. Excitation of hypersonic acoustic waves in diamond-based piezoelectric layered structure on the microwave frequencies up to 20GHz.

    PubMed

    Sorokin, B P; Kvashnin, G M; Novoselov, A S; Bormashov, V S; Golovanov, A V; Burkov, S I; Blank, V D

    2017-07-01

    First ultrahigh frequency (UHF) investigation of quality factor Q for the piezoelectric layered structure «Al/(001)AlN/Mo/(100) diamond» has been executed in a broad frequency band from 1 up to 20GHz. The record-breaking Q·f quality parameter up to 2.7·10(14)Hz has been obtained close to 20GHz. Frequency dependence of the form factor m correlated with quality factor has been analyzed by means of computer simulation, and non-monotonic frequency dependence can be explained by proper features of thin-film piezoelectric transducer (TFPT). Excluding the minimal Q magnitudes measured at the frequency points associated with minimal TFPT effectiveness, one can prove a rule of Qf∼f observed for diamond on the frequencies above 1GHz and defined by Landau-Rumer's acoustic attenuation mechanism. Synthetic IIa-type diamond single crystal as a substrate material for High-overtone Bulk Acoustic Resonator (HBAR) possesses some excellent acoustic properties in a wide microwave band and can be successfully applied for design of acoustoelectronic devices, especially the ones operating at a far UHF band. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Excitation of dust acoustic waves by an ion beam in a plasma cylinder with negatively charged dust grains

    SciTech Connect

    Sharma, Suresh C.; Kaur, Daljeet; Gahlot, Ajay; Sharma, Jyotsna

    2014-10-15

    An ion beam propagating through a plasma cylinder having negatively charged dust grains drives a low frequency electrostatic dust acoustic wave (DAW) to instability via Cerenkov interaction. The unstable wave frequencies and the growth rate increase with the relative density of negatively charged dust grains. The growth rate of the unstable mode scales to the one-third power of the beam density. The real part of the frequency of the unstable mode increases with the beam energy and scales to almost one-half power of the beam energy. The phase velocity, frequency, and wavelength results of the unstable mode are in compliance with the experimental observations.

  15. Design and implementation of improved LsCpLp resonant circuit for power supply for high-power electromagnetic acoustic transducer excitation

    NASA Astrophysics Data System (ADS)

    Zao, Yongming; Ouyang, Qi; Chen, Jiawei; Zhang, Xinglan; Hou, Shuaicheng

    2017-08-01

    This paper investigates the design and implementation of an improved series-parallel inductor-capacitor-inductor (LsCpLp) resonant circuit power supply for excitation of electromagnetic acoustic transducers (EMATs). The main advantage of the proposed resonant circuit is the absence of a high-permeability dynamic transformer. A high-frequency pulsating voltage gain can be achieved through a double resonance phenomenon. Both resonant tailing behavior and higher harmonics are suppressed by the improved resonant circuit, which also contributes to the generation of ultrasonic waves. Additionally, the proposed circuit can realize impedance matching and can also optimize the transduction efficiency. The complete design and implementation procedure for the power supply is described and has been validated by implementation of the proposed power supply to drive a portable EMAT. The circuit simulation results show close agreement with the experimental results and thus confirm the validity of the proposed topology. The proposed circuit is suitable for use as a portable EMAT excitation power supply that is fed by a low-voltage source.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

    Producing fluid structural interaction estimates of panel vibration from an applied pressure field excitation are quite dependent on the spatial correlation of the pressure field. There is a danger of either over estimating a low frequency response or under predicting broad band panel response in the more modally dense bands if the pressure field spatial correlation is not accounted for adequately. It is a useful practice to simulate the spatial correlation of the applied pressure field over a 2d surface using a matrix of small patch area regions on a finite element model (FEM). Use of a fitted function for the spatial correlation between patch centers can result in an error if the choice of patch density is not fine enough to represent the more continuous spatial correlation function throughout the intended frequency range of interest. Several patch density assumptions to approximate the fitted spatial correlation function are first evaluated using both qualitative and quantitative illustrations. The actual response of a typical vehicle panel system FEM is then examined in a convergence study where the patch density assumptions are varied over the same model. The convergence study results illustrate the impacts possible from a poor choice of patch density on the analytical response estimate. The fitted correlation function used in this study represents a diffuse acoustic field (DAF) excitation of the panel to produce vibration response.

  18. Design and implementation of improved LsCpLp resonant circuit for power supply for high-power electromagnetic acoustic transducer excitation.

    PubMed

    Zao, Yongming; Ouyang, Qi; Chen, Jiawei; Zhang, Xinglan; Hou, Shuaicheng

    2017-08-01

    This paper investigates the design and implementation of an improved series-parallel inductor-capacitor-inductor (LsCpLp) resonant circuit power supply for excitation of electromagnetic acoustic transducers (EMATs). The main advantage of the proposed resonant circuit is the absence of a high-permeability dynamic transformer. A high-frequency pulsating voltage gain can be achieved through a double resonance phenomenon. Both resonant tailing behavior and higher harmonics are suppressed by the improved resonant circuit, which also contributes to the generation of ultrasonic waves. Additionally, the proposed circuit can realize impedance matching and can also optimize the transduction efficiency. The complete design and implementation procedure for the power supply is described and has been validated by implementation of the proposed power supply to drive a portable EMAT. The circuit simulation results show close agreement with the experimental results and thus confirm the validity of the proposed topology. The proposed circuit is suitable for use as a portable EMAT excitation power supply that is fed by a low-voltage source.

  19. Direct-field acoustic testing of a flight system : logistics, challenges, and results.

    SciTech Connect

    Stasiunas, Eric Carl; Gurule, David Joseph; Babuska, Vit; Skousen, Troy J.

    2010-10-01

    Before a spacecraft can be considered for launch, it must first survive environmental testing that simulates the launch environment. Typically, these simulations include vibration testing performed using an electro-dynamic shaker. For some spacecraft however, acoustic excitation may provide a more severe loading environment than base shaker excitation. Because this was the case for a Sandia Flight System, it was necessary to perform an acoustic test prior to launch in order to verify survival due to an acoustic environment. Typically, acoustic tests are performed in acoustic chambers, but because of scheduling, transportation, and cleanliness concerns, this was not possible. Instead, the test was performed as a direct field acoustic test (DFAT). This type of test consists of surrounding a test article with a wall of speakers and controlling the acoustic input using control microphones placed around the test item, with a closed-loop control system. Obtaining the desired acoustic input environment - proto-flight random noise input with an overall sound pressure level (OASPL) of 146.7 dB-with this technique presented a challenge due to several factors. An acoustic profile with this high OASPL had not knowingly been obtained using the DFAT technique prior to this test. In addition, the test was performed in a high-bay, where floor space and existing equipment constrained the speaker circle diameter. And finally, the Flight System had to be tested without contamination of the unit, which required a contamination bag enclosure of the test unit. This paper describes in detail the logistics, challenges, and results encountered while performing a high-OASPL, direct-field acoustic test on a contamination-sensitive Flight System in a high-bay environment.

  20. Simulation using computer-piloted point excitations of vibrations induced on a structure by an acoustic environment

    NASA Astrophysics Data System (ADS)

    Monteil, P.

    1981-11-01

    Computation of the overall levels and spectral densities of the responses measured on a launcher skin, the fairing for instance, merged into a random acoustic environment during take off, was studied. The analysis of transmission of these vibrations to the payload required the simulation of these responses by a shaker control system, using a small number of distributed shakers. Results show that this closed loop computerized digital system allows the acquisition of auto and cross spectral densities equal to those of the responses previously computed. However, wider application is sought, e.g., road and runway profiles. The problems of multiple input-output system identification, multiple true random signal generation, and real time programming are evoked. The system should allow for the control of four shakers.

  1. Validation of Vehicle Panel/Equipment Response from Diffuse Acoustic Field Excitation Using Spatially Correlated Transfer Function Approach

    NASA Technical Reports Server (NTRS)

    Smith, Andrew; LaVerde, Bruce; Fulcher, Clay; Hunt, Ron

    2012-01-01

    An approach for predicting the vibration, strain, and force responses of a flight-like vehicle panel assembly to acoustic pressures is presented. Important validation for the approach is provided by comparison to ground test measurements in a reverberant chamber. The test article and the corresponding analytical model were assembled in several configurations to demonstrate the suitability of the approach for response predictions when the vehicle panel is integrated with equipment. Critical choices in the analysis necessary for convergence of the predicted and measured responses are illustrated through sensitivity studies. The methodology includes representation of spatial correlation of the pressure field over the panel surface. Therefore, it is possible to demonstrate the effects of hydrodynamic coincidence in the response. The sensitivity to pressure patch density clearly illustrates the onset of coincidence effects on the panel response predictions.

  2. Line-focus probe excitation of Scholte acoustic waves at the liquid-loaded surfaces of periodic structures

    SciTech Connect

    Every, A.G.; Vines, R.E.; Wolfe, J.P.

    1999-10-01

    A model is introduced to explain our observation of Scholte-like ultrasonic waves traveling at the water-loaded surfaces of solids with periodically varying properties. The observations pertain to two two-dimensional superlattices: a laminated solid of alternating 0.5-mm-thick layers of aluminum and a polymer, and a hexagonal array of polymer rods of lattice spacing 1 mm in an aluminum matrix. The surface waves are generated and detected by line focus acoustic lenses aligned parallel to each other, and separated by varying distances. The acoustic fields of these lenses may be considered a superposition of plain bulk waves with wave normals contained within the angular apertures of the lenses. For homogeneous solids, phase matching constraints do not allow the Scholte wave to be coupled into with an experimental configuration of this type. This is not true for a spatially periodic solid, where coupling between bulk waves and the Scholte surface wave takes place through Umklapp processes involving a change in the wave-vector component parallel to the surface by a reciprocal lattice vector. In the experiments, the source pulse is broadband, extending up to about 6 MHz, whereas the spectrum of the observed Scholte wave is peaked at around 4 and 4.5 MHz for the layered solid and hexagonal lattice, respectively. We attribute this to a resonance in the surface response of the solid, possibly associated with a critical point in the dispersion relation of the superlattice. On rotating the solid about its surface normal, the Scholte wave displays dramatic variation in phase arrival time and, to a lesser extent, also group arrival time. This variation is well accounted for by our model. {copyright} {ital 1999} {ital The American Physical Society}

  3. Launch Vehicles

    NASA Image and Video Library

    2007-09-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. Launch Pad 39B of the Kennedy Space Flight Center (KSC), currently used for Space Shuttle launches, will be revised to host the Ares launch vehicles. The fixed and rotating service structures standing at the pad will be dismantled sometime after the Ares I-X test flight. A new launch tower for Ares I will be built onto a new mobile launch platform. The gantry for the shuttle doesn't reach much higher than the top of the four segments of the solid rocket booster. Pad access above the current shuttle launch pad structure will not be required for Ares I-X because the stages above the solid rocket booster are inert. For the test scheduled in 2012 or for the crewed flights, workers and astronauts will need access to the highest levels of the rocket and capsule. When the Ares I rocket rolls out to the launch pad on the back of the same crawler-transporters used now, its launch gantry will be with it. The mobile launchers will nestle under three lightning protection towers to be erected around the pad area. Ares time at the launch pad will be significantly less than the three weeks or more the shuttle requires. This “clean pad” approach minimizes equipment and servicing at the launch pad. It is the same plan NASA used with the Saturn V rockets and industry employs it with more modern launchers. The launch pad will also get a new emergency escape system for astronauts, one that looks very much like a roller coaster. Cars riding on a rail will replace the familiar baskets hanging from steel cables. This artist's concept illustrates the Ares I on launch pad 39B.

  4. Launch vehicle

    NASA Astrophysics Data System (ADS)

    Rutledge, William S.

    1994-06-01

    Concentrated efforts by NASA and the DOD to begin development of a new large launch vehicle have been under way for over a decade. Options include the National Launch System, Advanced Launch System, a heavy lift vehicle, a Shuttle-derived vehicle, a Titan-derived vehicle, Single stage To Orbit, NASP and Spacelifter, to name a few. All initially promised low operations costs achieved at development costs in the $5 billion - $10 billion range. However, none has obtained approval for development, primarily because it became apparent that these cost goals could not realistically be met.

  5. NPP Launch

    NASA Image and Video Library

    NASA's National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) spacecraft was launched aboard a Delta II rocket at 5:48 a.m. EDT today, on a mission to measure ...

  6. Orion Launch

    NASA Image and Video Library

    2014-12-05

    A Delta IV Heavy rocket lifts off from Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida carrying NASA's Orion spacecraft on an unpiloted flight test to Earth orbit. Liftoff was at 7:05 a.m. EST. During the two-orbit, four-and-a-half hour mission, engineers will evaluate the systems critical to crew safety, the launch abort system, the heat shield and the parachute system.

  7. Observation of skull-guided acoustic waves in a water-immersed murine skull using optoacoustic excitation

    NASA Astrophysics Data System (ADS)

    Estrada, Héctor; Rebling, Johannes; Razansky, Daniel

    2017-02-01

    The skull bone, a curved solid multilayered plate protecting the brain, constitutes a big challenge for the use of ultrasound-mediated techniques in neuroscience. Ultrasound waves incident from water or soft biological tissue are mostly reflected when impinging on the skull. To this end, skull properties have been characterized for both high-intensity focused ultrasound (HIFU) operating in the narrowband far-field regime and optoacoustic imaging applications. Yet, no study has been conducted to characterize the near-field of water immersed skulls. We used the thermoelastic effect with a 532 nm pulsed laser to trigger a wide range of broad-band ultrasound modes in a mouse skull. In order to capture the waves propagating in the near-field, a thin hydrophone was scanned in close proximity to the skull's surface. While Leaky pseudo-Lamb waves and grazing-angle bulk water waves are clearly visible in the spatio-temporal data, we were only able to identify skull-guided acoustic waves after dispersion analysis in the wavenumber-frequency space. The experimental data was found to be in a reasonable agreement with a flat multilayered plate model.

  8. Exploring the Angstrom Excursion of Au Nanoparticles Excited away from a Metal Surface by an Impulsive Acoustic Perturbation.

    PubMed

    Kim, Ji-Wan; Kovalenko, Oleksandr; Liu, Yu; Bigot, Jean-Yves

    2016-12-27

    We report the anharmonic angstrom dynamics of self-assembled Au nanoparticles (Au:NPs) away from a nickel surface on top of which they are coupled by their near-field interaction. The deformation and the oscillatory excursion away from the surface are induced by picosecond acoustic pulses and probed at the surface plasmon resonance with femtosecond laser pulses. The overall dynamics are due to an efficient transfer of translational momentum from the Ni surface to the Au:NPs, therefore avoiding usual thermal effects and energy redistribution among the electronic states. Two modes are clearly revealed by the oscillatory shift of the Au:NPs surface plasmon resonance-the quadrupole deformation mode due to the transient ellipsoid shape and the excursion mode when the Au:NPs bounce away from the surface. We find that, contrary to the quadrupole mode, the excursion mode is sensitive to the distance between Au:NPs and Ni. Importantly, the excursion dynamics display a nonsinusoidal motion that cannot be explained by a standard harmonic potential model. A detailed modeling of the dynamics using a Hamaker-type Lennard-Jones potential between two media is performed, showing that each Au:NPs coherently evolves in a nearly one-dimensional anharmonic potential with a total excursion of ∼1 Å. This excursion induces a shift of the surface plasmon resonance detectable because of the strong near-field interaction. This general method of observing the spatiotemporal dynamics with angstrom and picosecond resolutions can be directly transposed to many nanostructures or biosystems to reveal the interaction and contact mechanism with their surrounding medium while remaining in their fundamental electronic states.

  9. Launch Vehicles

    NASA Image and Video Library

    1961-01-01

    This is a comparison illustration of the Redstone, Jupiter-C, and Mercury Redstone launch vehicles. The Redstone ballistic missile was a high-accuracy, liquid-propelled, surface-to-surface missile. Originally developed as a nose cone re-entry test vehicle for the Jupiter intermediate range ballistic missile, the Jupiter-C was a modification of the Redstone missile and successfully launched the first American Satellite, Explorer-1, in orbit on January 31, 1958. The Mercury Redstone lifted off carrying the first American, astronaut Alan Shepard, in his Mercury spacecraft Freedom 7, on May 5, 1961.

  10. Acoustic Suppression Systems and Related Methods

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R. (Inventor); Kern, Dennis L. (Inventor)

    2013-01-01

    An acoustic suppression system for absorbing and/or scattering acoustic energy comprising a plurality of acoustic targets in a containment is described, the acoustic targets configured to have resonance frequencies allowing the targets to be excited by incoming acoustic waves, the resonance frequencies being adjustable to suppress acoustic energy in a set frequency range. Methods for fabricating and implementing the acoustic suppression system are also provided.

  11. Launching "Dunno"

    ERIC Educational Resources Information Center

    Inson, Peter

    2005-01-01

    This article, written in response to an invitation from "CLE," describes the origins and controversial content of "dunno," a first novel, self-published by Peter Inson, a former teacher and headmaster. Inson considers influences upon his writing, the thinking which led him towards self-publication and the process of personally launching and…

  12. 75 FR 28587 - Taking and Importing Marine Mammals; Taking Marine Mammals Incidental to Missile Launch...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-21

    .... The launch azimuths caused the vehicles to pass over or near various pinniped monitoring and acoustic measurement sites where Autonomous Terrestrial Acoustic Recorders (ATARs) and video systems had been deployed... operations from SNI on marine mammals involve both acoustic and non-acoustic effects. Acoustic effects...

  13. Launch vehicles

    NASA Astrophysics Data System (ADS)

    Moss, J. B.

    The basic principles which determine launcher design and hence constrain the spacecraft payload are determined. Some key features of the principal launcher alternatives in Europe and the U.S., namely, the unmanned, expendable Ariane and the manned, substantially reusable, Space Shuttle, are outlined. The equations of motion of the rocket are specialized to the vertical plane, parallel and normal to the flight direction, and to the motion of the center of mass and the pitch rotation. A typical Ariane 2 flight profile for transfer into GTO is illustrated. Some representative mission requirements for spacecraft launches are reviewed. Launch vehicle burnout velocities for spacecraft emplacement are given. Geostationary orbit emplacement, orbital mission performance, and configuration interactions are discussed.

  14. Initial Assessment of the Ares I-X Launch Vehicle Upper Stage to Vibroacoustic Flight Environments

    NASA Technical Reports Server (NTRS)

    Larko, Jeffrey M.; Hughes, William O.

    2008-01-01

    The Ares I launch vehicle will be NASA s first new launch vehicle since 1981. Currently in design, it will replace the Space Shuttle in taking astronauts to the International Space Station, and will eventually play a major role in humankind s return to the Moon and eventually to Mars. Prior to any manned flight of this vehicle, unmanned test readiness flights will be flown. The first of these readiness flights, named Ares I-X, is scheduled to be launched in April 2009. The NASA Glenn Research Center is responsible for the design, manufacture, test and analysis of the Ares I-X upper stage simulator (USS) element. As part of the design effort, the structural dynamic response of the Ares I-X launch vehicle to its vibroacoustic flight environments must be analyzed. The launch vehicle will be exposed to extremely high acoustic pressures during its lift-off and aerodynamic stages of flight. This in turn will cause high levels of random vibration on the vehicle's outer surface that will be transmitted to its interior. Critical flight equipment, such as its avionics and flight guidance components are susceptible to damage from this excitation. This study addresses the modelling, analysis and predictions from examining the structural dynamic response of the Ares I-X upper stage to its vibroacoustic excitations. A statistical energy analysis (SEA) model was used to predict the high frequency response of the vehicle at locations of interest. Key to this study was the definition of the excitation fields corresponding to lift off acoustics and the unsteady aerodynamic pressure fluctuations during flight. The predicted results will be used by the Ares I-X Project to verify the flight qualification status of the Ares I-X upper stage components.

  15. LADEE Launch

    NASA Image and Video Library

    2013-09-07

    NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) observatory launches aboard the Minotaur V rocket from the Mid-Atlantic Regional Spaceport (MARS) at NASA's Wallops Flight Facility, Friday, Sept. 6, 2013 in Virginia. LADEE is a robotic mission that will orbit the moon where it will provide unprecedented information about the environment around the moon and give scientists a better understanding of other planetary bodies in our solar system and beyond. Photo Credit: (NASA/Carla Cioffi)

  16. Launch Vehicles

    NASA Image and Video Library

    2004-04-15

    The Titan II liftoff. The Titan II launch vehicle was used for carrying astronauts on the Gemini mission. The Gemini Program was an intermediate step between the Project Mercury and the Apollo Program. The major objectives were to subject are two men and supporting equipment to long duration flights, to effect rendezvous and docking with other orbiting vehicle, and to perfect methods of reentry, and landing the spacecraft.

  17. Launch Vehicles

    NASA Image and Video Library

    2007-07-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. In this HD video image, an Ares I x-test involves the upper stage separating from the first stage. This particular test was conducted at the NASA Langley Research Center in July 2007. (Highest resolution available)

  18. Acoustic-Levitation Chamber

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Granett, D.; Lee, M. C.

    1984-01-01

    Uncontaminated environments for highly-pure material processing provided within completely sealed levitation chamber that suspends particles by acoustic excitation. Technique ideally suited for material processing in low gravity environment of space.

  19. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts the preparation and placement of a confidence ring for friction stir welding used in manufacturing aluminum panels that will fabricate the Ares I upper stage barrel. The aluminum panels are manufactured and subjected to confidence tests during which the bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  20. Launch Vehicles

    NASA Image and Video Library

    2006-09-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. In this HD video image, the first stage reentry parachute drop test is conducted at the Yuma, Arizona proving ground. The parachute tests demonstrated a three-stage deployment sequence that included the use of an Orbiter drag chute to properly stage the unfurling of the main chute. The parachute recovery system for Orion will be similar to the system used for Apollo command module landings and include two drogue, three pilot, and three main parachutes. (Highest resolution available)

  1. Launch Vehicles

    NASA Image and Video Library

    2007-09-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. In this HD video image, the first stage reentry parachute drop test is conducted at the Yuma, Arizona proving ground. The parachute tests demonstrated a three-stage deployment sequence that included the use of an Orbiter drag chute to properly stage the unfurling of the main chute. The parachute recovery system for Orion will be similar to the system used for Apollo command module landings and include two drogue, three pilot, and three main parachutes. (Highest resolution available)

  2. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. In this HD video image, processes for upper stage barrel fabrication are talking place. Aluminum panels are manufacturing process demonstration articles that will undergo testing until perfected. The panels are built by AMRO Manufacturing located in El Monte, California. (Largest resolution available)

  3. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts the manufacturing of aluminum panels that will be used to form the Ares I barrel. The panels are manufacturing process demonstration articles that will undergo testing until perfected. The panels are built by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  4. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts friction stir welding used in manufacturing aluminum panels that will fabricate the Ares I upper stage barrel. The panels are subjected to confidence tests in which the bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  5. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image, depicts a manufactured aluminum panel, that will be used to fabricate the Ares I upper stage barrel, undergoing a confidence panel test. In this test, the bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  6. Launch Vehicles

    NASA Image and Video Library

    2006-08-08

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts a manufactured aluminum panel that will be used to fabricate the Ares I upper stage barrel, undergoing a confidence panel test. In this test, the bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  7. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts confidence testing of a manufactured aluminum panel that will fabricate the Ares I upper stage barrel. In this test, bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  8. Launch Vehicles

    NASA Image and Video Library

    2006-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts a manufactured aluminum panel, that will fabricate the Ares I upper stage barrel, undergoing a confidence panel test. In this test, bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  9. Launch Vehicles

    NASA Image and Video Library

    2007-08-09

    Under the goals of the Vision for Space Exploration, Ares I is a chief component of the cost-effective space transportation infrastructure being developed by NASA's Constellation Program. This transportation system will safely and reliably carry human explorers back to the moon, and then onward to Mars and other destinations in the solar system. The Ares I effort includes multiple project element teams at NASA centers and contract organizations around the nation, and is managed by the Exploration Launch Projects Office at NASA's Marshall Space Flight Center (MFSC). ATK Launch Systems near Brigham City, Utah, is the prime contractor for the first stage booster. ATK's subcontractor, United Space Alliance of Houston, is designing, developing and testing the parachutes at its facilities at NASA's Kennedy Space Center in Florida. NASA's Johnson Space Center in Houston hosts the Constellation Program and Orion Crew Capsule Project Office and provides test instrumentation and support personnel. Together, these teams are developing vehicle hardware, evolving proven technologies, and testing components and systems. Their work builds on powerful, reliable space shuttle propulsion elements and nearly a half-century of NASA space flight experience and technological advances. Ares I is an inline, two-stage rocket configuration topped by the Crew Exploration Vehicle, its service module, and a launch abort system. This HD video image depicts a manufactured aluminum panel, that will fabricate the Ares I upper stage barrel, undergoing a confidence panel test. In this test, the bent aluminum is stressed to breaking point and thoroughly examined. The panels are manufactured by AMRO Manufacturing located in El Monte, California. (Highest resolution available)

  10. Acoustic Test Characterization of Melamine Foam for Usage in NASA's Payload Fairing Acoustic Attenuation Systems

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.; McNelis, Mark E.

    2014-01-01

    The external acoustic liftoff levels predicted for NASA's future heavy lift launch vehicles are expected to be significantly higher than the environment created by today's commercial launch vehicles. This creates a need to develop an improved acoustic attenuation system for future NASA payload fairings. NASA Glenn Research Center initiated an acoustic test series to characterize the acoustic performance of melamine foam, with and without various acoustic enhancements. This testing was denoted as NEMFAT, which stands for NESC Enhanced Melamine Foam Acoustic Test, and is the subject of this paper. Both absorption and transmission loss testing of numerous foam configurations were performed at the Riverbank Acoustical Laboratory in July 2013. The NEMFAT test data provides an initial acoustic characterization and database of melamine foam for NASA. Because of its acoustic performance and lighter mass relative to fiberglass blankets, melamine foam is being strongly considered for use in the acoustic attenuation systems of NASA's future launch vehicles.

  11. A Correlated Study of the Response of a Satellite to Acoustic Radiation Using Statistical Energy Analysis and Acoustic Test Data

    SciTech Connect

    CAP,JEROME S.; TRACEY,BRIAN

    1999-11-15

    Aerospace payloads, such as satellites, are subjected to vibroacoustic excitation during launch. Sandia's MTI satellite has recently been certified to this environment using a combination of base input random vibration and reverberant acoustic noise. The initial choices for the acoustic and random vibration test specifications were obtained from the launch vehicle Interface Control Document (ICD). In order to tailor the random vibration levels for the laboratory certification testing, it was necessary to determine whether vibration energy was flowing across the launch vehicle interface from the satellite to the launch vehicle or the other direction. For frequencies below 120 Hz this issue was addressed using response limiting techniques based on results from the Coupled Loads Analysis (CLA). However, since the CLA Finite Element Analysis FEA model was only correlated for frequencies below 120 Hz, Statistical Energy Analysis (SEA) was considered to be a better choice for predicting the direction of the energy flow for frequencies above 120 Hz. The existing SEA model of the launch vehicle had been developed using the VibroAcoustic Payload Environment Prediction System (VAPEPS) computer code [1]. Therefore, the satellite would have to be modeled using VAPEPS as well. As is the case for any computational model, the confidence in its predictive capability increases if one can correlate a sample prediction against experimental data. Fortunately, Sandia had the ideal data set for correlating an SEA model of the MTI satellite--the measured response of a realistic assembly to a reverberant acoustic test that was performed during MTI's qualification test series. The first part of this paper will briefly describe the VAPEPS modeling effort and present the results of the correlation study for the VAPEPS model. The second part of this paper will present the results from a study that used a commercial SEA software package [2] to study the effects of in-plane modes and to

  12. Acoustic neuroma

    MedlinePlus

    Vestibular schwannoma; Tumor - acoustic; Cerebellopontine angle tumor; Angle tumor; Hearing loss - acoustic; Tinnitus - acoustic ... Acoustic neuromas have been linked with the genetic disorder neurofibromatosis type 2 (NF2). Acoustic neuromas are uncommon.

  13. Vector network analyzer measurement of the amplitude of an electrically excited surface acoustic wave and validation by X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Camara, I. S.; Croset, B.; Largeau, L.; Rovillain, P.; Thevenard, L.; Duquesne, J.-Y.

    2017-01-01

    Surface acoustic waves are used in magnetism to initiate magnetization switching, in microfluidics to control fluids and particles in lab-on-a-chip devices, and in quantum systems like two-dimensional electron gases, quantum dots, photonic cavities, and single carrier transport systems. For all these applications, an easy tool is highly needed to measure precisely the acoustic wave amplitude in order to understand the underlying physics and/or to optimize the device used to generate the acoustic waves. We present here a method to determine experimentally the amplitude of surface acoustic waves propagating on Gallium Arsenide generated by an interdigitated transducer. It relies on Vector Network Analyzer measurements of S parameters and modeling using the Coupling-Of-Modes theory. The displacements obtained are in excellent agreement with those measured by a very different method based on X-ray diffraction measurements.

  14. Space Launch System Begins Acoustic Testing

    NASA Image and Video Library

    Engineers at NASA's Marshall Space Flight Center in Huntsville, Ala., have assembled a collection of thrusters to stand in for the various propulsion elements in a scale model version of NASA’s S...

  15. The Standard Deviation of Launch Vehicle Environments

    NASA Technical Reports Server (NTRS)

    Yunis, Isam

    2005-01-01

    Statistical analysis is used in the development of the launch vehicle environments of acoustics, vibrations, and shock. The standard deviation of these environments is critical to accurate statistical extrema. However, often very little data exists to define the standard deviation and it is better to use a typical standard deviation than one derived from a few measurements. This paper uses Space Shuttle and expendable launch vehicle flight data to define a typical standard deviation for acoustics and vibrations. The results suggest that 3dB is a conservative and reasonable standard deviation for the source environment and the payload environment.

  16. SLS Scale Model Acoustic Test Liftoff Results and Comparisons

    NASA Technical Reports Server (NTRS)

    Houston, Janice; Counter, Douglas; Giacomoni, Clothilde

    2015-01-01

    The liftoff phase induces acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are then used in the prediction of internal vibration responses of the vehicle and components which result in the qualification levels. Thus, predicting these liftoff acoustic (LOA) environments is critical to the design requirements of any launch vehicle. If there is a significant amount of uncertainty in the predictions or if acoustic mitigation options must be implemented, a subscale acoustic test is a feasible design phase test option to verify the LOA environments. The NASA Space Launch System (SLS) program initiated the Scale Model Acoustic Test (SMAT) to verify the predicted SLS LOA environments.

  17. Scale Model Acoustic Test Overview

    NASA Technical Reports Server (NTRS)

    Counter, Douglas D.; Houston, Janice D.

    2012-01-01

    Launch environments, such as liftoff acoustic (LOA) and ignition overpressure (IOP), are important design factors for any vehicle and are dependent upon the design of both the vehicle and the ground systems. LOA environments are used directly in the development of vehicle vibro-acoustic environments and IOP is used in the loads assessment. The Scale Model Acoustic Test (SMAT) program was implemented to verify the Space Launch Systems LOA and IOP environments for the vehicle and ground systems including the Mobile Launcher (ML) and tower. The SMAT is currently in the design and fabrication phase. The SMAT program is described in this presentation.

  18. Venture Class Launch Services

    NASA Technical Reports Server (NTRS)

    Wiese, Mark

    2016-01-01

    Provide an introduction to the Launch Services Program, and specifically the strategic initiative that drove the Venture Class Launch Services contracts. Provide information from the VCLS request for proposals, as well as the Agency's CubeSat Launch Initiative.

  19. Launch summary for 1978

    NASA Technical Reports Server (NTRS)

    Vostreys, R. W.

    1978-01-01

    Sounding rocket, satellite, and space probe launchings are presented. Time, date, and location of the launches are provided. The sponsoring countries and the institutions responsible for the launch are listed.

  20. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice D.

    2014-01-01

    The liftoff phase induces some of the highest acoustic loading over a broad frequency for a launch vehicle. These external acoustic environments are used in the prediction of the internal vibration responses of the vehicle and components. Thus, predicting these liftoff acoustic environments is critical to the design requirements of any launch vehicle but there are challenges. Present liftoff vehicle acoustic environment prediction methods utilize stationary data from previously conducted hold-down tests; i.e. static firings conducted in the 1960's, to generate 1/3 octave band Sound Pressure Level (SPL) spectra. These data sets are used to predict the liftoff acoustic environments for launch vehicles. To facilitate the accuracy and quality of acoustic loading, predictions at liftoff for future launch vehicles such as the Space Launch System (SLS), non-stationary flight data from the Ares I-X were processed in PC-Signal in two forms which included a simulated hold-down phase and the entire launch phase. In conjunction, the Prediction of Acoustic Vehicle Environments (PAVE) program was developed in MATLAB to allow for efficient predictions of sound pressure levels (SPLs) as a function of station number along the vehicle using semiempirical methods. This consisted, initially, of generating the Dimensionless Spectrum Function (DSF) and Dimensionless Source Location (DSL) curves from the Ares I-X flight data. These are then used in the MATLAB program to generate the 1/3 octave band SPL spectra. Concluding results show major differences in SPLs between the hold-down test data and the processed Ares IX flight data making the Ares I-X flight data more practical for future vehicle acoustic environment predictions.

  1. Scale Model Thruster Acoustic Measurement Results

    NASA Technical Reports Server (NTRS)

    Kenny, R. Jeremy; Vargas, Magda B.

    2013-01-01

    Subscale rocket acoustic data is used to predict acoustic environments for full scale rockets. Over the last several years acoustic data has been collected during horizontal tests of solid rocket motors. Space Launch System (SLS) Scale Model Acoustic Test (SMAT) was designed to evaluate the acoustics of the SLS vehicle including the liquid engines and solid rocket boosters. SMAT is comprised of liquid thrusters scalable to the Space Shuttle Main engines (SSME) and Rocket Assisted Take Off (RATO) motors scalable to the 5-segment Reusable Solid Rocket Motor (RSTMV). Horizontal testing of the liquid thrusters provided an opportunity to collect acoustic data from liquid thrusters to characterize the acoustic environments. Acoustic data was collected during the horizontal firings of a single thruster and a 4-thruster (Quad) configuration. Presentation scope. Discuss the results of the single and 4-thruster acoustic measurements. Compare the measured acoustic levels of the liquid thrusters to the Solid Rocket Test Motor V - Nozzle 2 (SRTMV-N2).

  2. Investigation of Passive Control Devices for Potential Application to a Launch Vehicle Structure to Reduce the Interior Noise Levels During Launch

    DTIC Science & Technology

    2006-05-25

    Investigation of acoustic fields for the Cassini spacecraft : Reverberant versus launch environments. Techni- cal Memorandum NASA/TM-2000-209387; E-11814; AIAA...structural-acoustic control of a rocket fairing using proof-mass actuators. Journal of Spacecraft and Rockets, 38(2):219–225, March/April 2001. [28] H. Defosse...Fairing noise reduction for directive acoustic fields. In Spacecraft and Launch Vehicle Dynamic Environments Workshop, El Segundo, California, USA

  3. Adaptive Immersed Boundary Simulations for the Launch Environment

    NASA Technical Reports Server (NTRS)

    Barad, Michael F.; Housman, Jeffrey A.; Kiris, Cetin C.

    2012-01-01

    A high-fidelity computational fluid dynamics simulation of a next generation heavy lift space vehicle during launch is presented. The purpose of the simulation is to evaluate the acoustic overpressures during ignition to permit re-design of the launch site to safely handle heavy lift vehicles. The simulation is performed using the Launch, Ascent, and Vehicle Aerodynamics (LAVA) code, an immersed boundary block-structured Cartesian adaptive mesh refinement based solver. A verification and validation study of LAVA in the launch environment context is also performed, comparing to flight data and previous simulations of a Space Shuttle launch

  4. STS-120 launch

    NASA Image and Video Library

    2007-10-23

    STS120-S-026 (23 Oct. 2007) --- In the firing room of the Kennedy Space Center in Florida, NASA Shuttle Launch Director Michael Leinbach (second right) and launch managers watch the 11:38 a.m. (EDT) launch of Space Shuttle Discovery. Discovery launched Oct. 23 on a 14-day construction mission to the International Space Station. Photo credit: NASA/Bill Ingalls

  5. Acoustic actuation of bioinspired microswimmers.

    PubMed

    Kaynak, Murat; Ozcelik, Adem; Nourhani, Amir; Lammert, Paul E; Crespi, Vincent H; Huang, Tony Jun

    2017-01-31

    Acoustic actuation of bioinspired microswimmers is experimentally demonstrated. Microswimmers are fabricated in situ in a microchannel. Upon acoustic excitation, the flagellum of the microswimmer oscillates, which in turn generates linear or rotary movement depending on the swimmer design. The speed of these bioinspired microswimmers is tuned by adjusting the voltage amplitude applied to the acoustic transducer. Simple microfabrication and remote actuation are promising for biomedical applications.

  6. KENNEDY SPACE CENTER, FLA. - Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Researchers conduct underwater acoustic research in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  7. Acoustic Levitation With One Transducer

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B.

    1987-01-01

    Higher resonator modes enables simplification of equipment. Experimental acoustic levitator for high-temperature containerless processing has round cylindrical levitation chamber and only one acoustic transducer. Stable levitation of solid particle or liquid drop achieved by exciting sound in chamber to higher-order resonant mode that makes potential well for levitated particle or drop at some point within chamber.

  8. Space Shuttle Discovery Launch

    NASA Image and Video Library

    2008-05-31

    NASA Shuttle Launch Director Michael Leinbach, left, STS-124 Assistant Launch Director Ed Mango, center, and Flow Director for Space Shuttle Discovery Stephanie Stilson clap in the the Launch Control Center after the main engine cut off and successful launch of the Space Shuttle Discovery (STS-124) Saturday, May 31, 2008, at the Kennedy Space Center in Cape Canaveral, Fla. The Shuttle lifted off from launch pad 39A at 5:02 p.m. EDT. Photo Credit: (NASA/Bill Ingalls)

  9. Theoretical and numerical calculation of the acoustic radiation force acting on a circular rigid cylinder near a flat wall in a standing wave excitation in an ideal fluid.

    PubMed

    Wang, Jingtao; Dual, Jurg

    2012-02-01

    The acoustic radiation force acting on a cylinder near a flat wall in a standing wave is calculated by analytical methods and numerical simulations. An exact theoretical solution is presented as well as an approximate solution. The approximate solution is in algebraic form and quite easy to compute. The numerical simulation is based on FVM (Finite Volume Method) on unstructured triangular meshes. The exact theoretical, approximate and numerical solutions are compared with each other and good agreements are obtained. Furthermore, the effects of the flat wall are investigated in detail by the three methods. Copyright © 2011 Elsevier B.V. All rights reserved.

  10. Off-Resonance Acoustic Levitation Without Rotation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Allen, J. L.

    1984-01-01

    Orthogonal acoustic-levitation modes excited at slightly different frequencies to control rotation. Rotation of object in square cross-section acoustic-levitation chamber stopped by detuning two orthogonal (x and y) excitation drivers in plane of square cross section. Detuning done using fundamental degenerate modes or odd harmonic modes.

  11. Closed-Loop Acoustic Control of Reverberant Room for Satellite Environmental Testing

    NASA Astrophysics Data System (ADS)

    Janssens, Karl; Bianciardi, Fabio; Sabbatini, Danilo; Debille, Jan; Carrella, Alex

    2012-07-01

    The full satellite acoustic test is an important milestone in a satellite launch survivability verification campaign. This test is required to verify the satellite’s mechanical design against the high-level acoustic loads induced by the launch vehicle during the atmospheric flight. During the test, the satellite is subjected to a broadband diffuse acoustic field, reproducing the pressure levels observed during launch. The excitation is in most cases provided by a combination of horns for the low frequencies and noise generators for the higher frequencies. Acoustic control tests are commonly performed in reverberant rooms, controlling the sound pressure levels in third octave bands over the specified target spectrum. This paper discusses an automatic feedback control system for acoustic control of large reverberation rooms for satellite environmental testing. The acoustic control system consists of parallel third octave PI (Proportional Integral) feedback controllers that take the reverberation characteristics of the room into consideration. The drive output of the control system is shaped at every control step based on the comparison of the average third octave noise spectrum, measured from a number of microphones in the test room, with the target spectrum. Cross-over filters split the output drive into band- limited signals to feed each of the horns. The control system is realized in several steps. In the first phase, a dynamic process model is developed, including the non-linear characteristics of the horns and the reverberant properties of the room. The model is identified from dynamic experiments using system identification techniques. In the next phase, an adequate control strategy is designed which is capable of reaching the target spectrum in the required time period without overshoots. This control strategy is obtained from model-in-the-loop (MIL) simulations, evaluating the performance of various potential strategies. Finally, the proposed strategy is

  12. KENNEDY SPACE CENTER, FLA. - Justin Manley, of the National Oceanic and Atmospheric Administration, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Justin Manley, of the National Oceanic and Atmospheric Administration, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  13. KENNEDY SPACE CENTER, FLA. - Joe Bartoszek, NASA, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Joe Bartoszek, NASA, is a member of the research team conducting underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  14. KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Researchers utilize several types of watercraft to conduct underwater acoustic research in the Launch Complex 39 turn basin near Launch Pad 39A. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  15. Modulating Sound with Acoustic Metafiber Bundles.

    PubMed

    Xia, Jian-Ping; Sun, Hong-Xiang; Yuan, Shou-Qi

    2017-08-15

    Acoustic metamaterials and metasurfaces provide great flexibility for manipulating sound waves and promise unprecedented functionality, ranging from transformation acoustics, acoustic cloaking, acoustic imaging to acoustic rerouting. However, the design of artificial structures with both broad bandwidth and multifunctionality remains challenging with traditional design approaches. Here we present a design and realization of a broadband acoustic metafiber bundle. Very different from previously reported acoustic metamaterials and metasurfaces, not only the metafiber structure is simple, flexible and tunable, but also the metafiber bundle has the advantages of broad bandwidth, high transmission, no resonance-induced energy loss and unchangeable output wavefront owing to eigenmodes in the passbands of the metafiber. Besides, it could also achieve arbitrary complex modulations of cylindrical and plane acoustic wavefronts. The metafiber bundles realize the exciting multifunctionality of both acoustic metamaterials and metasurfaces in a broad frequency range, which provides diverse routes to design novel acoustic devices with versatile applications.

  16. Launching the Future... Constellation Program at KSC

    NASA Technical Reports Server (NTRS)

    Denson, Erik C.

    2010-01-01

    With the Constellation Program, NASA is entering a new age of space exploration that will take us back to the Moon, to Mars, and beyond, and NASA is developing the new technology and vehicles to take us there. At the forefront are the Orion spacecraft and the Ares I launch vehicle. As NASA's gateway to space, Kennedy Space Center (KSC) will process and launch the new vehicles. This will require new systems and extensive changes to existing infrastructure. KSC is designing a new mobile launcher, a new launch control system, and new ground support equipment; modifying the Vehicle Assembly Building, one of the launch pads, and other facilities; and launching the Ares I-X flight test. It is an exciting and challenging time to be an engineer at KSC.

  17. Acoustic Neuroma

    MedlinePlus

    ... search IRSA's site Unique Hits since January 2003 Acoustic Neuroma Click Here for Acoustic Neuroma Practice Guideline ... to microsurgery. One doctor's story of having an acoustic neuroma In August 1991, Dr. Thomas F. Morgan ...

  18. Detecting Contaminant Particles Acoustically

    NASA Technical Reports Server (NTRS)

    Wyett, L. M.

    1986-01-01

    Apparatus "listens" for particles in interior of complex turbomachinery. Contact microphones are attached at several points on pump housing. Acoustic transducer also attached to housing to excite entire pump with sound. Frequency of sound is slowly raised until pump resonates. Microphones detect noise of loose particles scraping against pump parts. Such as machining chips in turbopumps or other machinery without disassembly.

  19. Fifth FLTSATCOM to be launched

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Launch of the FLTSATOOM-E, into an elliptical orbit by the Atlas Centaur launch vehicle is announced. The launch and relevant launch operations are described. A chart of the launch sequence for FLTSATCOM-E communication satellite is given.

  20. Benefits of Government Incentives for Reusable Launch Vehicle Development

    NASA Technical Reports Server (NTRS)

    Shaw, Eric J.; Hamaker, Joseph W.; Prince, Frank A.

    1998-01-01

    Many exciting new opportunities in space, both government missions and business ventures, could be realized by a reduction in launch prices. Reusable launch vehicle (RLV) designs have the potential to lower launch costs dramatically from those of today's expendable and partially-expendable vehicles. Unfortunately, governments must budget to support existing launch capability, and so lack the resources necessary to completely fund development of new reusable systems. In addition, the new commercial space markets are too immature and uncertain to motivate the launch industry to undertake a project of this magnitude and risk. Low-cost launch vehicles will not be developed without a mature market to service; however, launch prices must be reduced in order for a commercial launch market to mature. This paper estimates and discusses the various benefits that may be reaped from government incentives for a commercial reusable launch vehicle program.

  1. Benefits of Government Incentives for Reusable Launch Vehicle Development

    NASA Technical Reports Server (NTRS)

    Shaw, Eric J.; Hamaker, Joseph W.; Prince, Frank A.

    1998-01-01

    Many exciting new opportunities in space, both government missions and business ventures, could be realized by a reduction in launch prices. Reusable launch vehicle (RLV) designs have the potential to lower launch costs dramatically from those of today's expendable and partially-expendable vehicles. Unfortunately, governments must budget to support existing launch capability, and so lack the resources necessary to completely fund development of new reusable systems. In addition, the new commercial space markets are too immature and uncertain to motivate the launch industry to undertake a project of this magnitude and risk. Low-cost launch vehicles will not be developed without a mature market to service; however, launch prices must be reduced in order for a commercial launch market to mature. This paper estimates and discusses the various benefits that may be reaped from government incentives for a commercial reusable launch vehicle program.

  2. Controlling Sample Rotation in Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Stoneburner, J. D.

    1985-01-01

    Rotation of acoustically levitated object stopped or controlled according to phase-shift monitoring and control concept. Principle applies to square-cross-section levitation chamber with two perpendicular acoustic drivers operating at same frequency. Phase difference between X and Y acoustic excitation measured at one corner by measuring variation of acoustic amplitude sensed by microphone. Phase of driver adjusted to value that produces no rotation or controlled rotation of levitated object.

  3. IRIS Launch Animation

    NASA Image and Video Library

    This animation demonstrates the launch and deployment of NASA's Interface Region Imaging Spectrograph (IRIS) mission satellite via a Pegasus rocket. The launch is scheduled for June 26, 2013 from V...

  4. Shuttle Era: Launch Directors

    NASA Image and Video Library

    A space shuttle launch director is the leader of the complex choreography that goes into a shuttle liftoff. Ten people have served as shuttle launch directors, making the final decision whether the...

  5. Space Launch System Animation

    NASA Image and Video Library

    NASA is ready to move forward with the development of the Space Launch System -- an advanced heavy-lift launch vehicle that will provide an entirely new national capability for human exploration be...

  6. Extreme driven ion acoustic waves

    NASA Astrophysics Data System (ADS)

    Friedland, L.; Shagalov, A. G.

    2017-08-01

    The excitation of large amplitude, strongly nonlinear ion acoustic waves from trivial equilibrium by a chirped frequency drive is discussed. Under certain conditions, after passage through the linear resonance in this system, the nonlinearity and the variation of parameters work in tandem to preserve the phase-locking with the driving wave via excursion of the excited ion acoustic wave in its parameter space, yielding controlled growth of the wave amplitude. We study these autoresonant waves via a fully nonlinear warm fluid model and predict the formation of sharply peaked (extreme) ion acoustic excitations with local ion density significantly exceeding the unperturbed plasma density. The driven wave amplitude is bound by the kinetic wave-breaking, as the local maximum fluid velocity of the wave approaches the phase velocity of the drive. The Vlasov-Poisson simulations are used to confirm the results of the fluid model, and Whitham's averaged variational principle is applied for analyzing the evolution of autoresonant ion acoustic waves.

  7. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-07

    NASA Administrator Charles Bolden, right, participates in the post launch traditional beans and cornbread at the NASA Kennedy Space Center, Launch Control Center (LCC) shortly after the space shuttle Atlantis, STS-135, launched on Friday, July 8, 2011, in Cape Canaveral, Fla. The launch of Atlantis is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  8. Launch Vehicle Operations Simulator

    NASA Technical Reports Server (NTRS)

    Blackledge, J. W.

    1974-01-01

    The Saturn Launch Vehicle Operations Simulator (LVOS) was developed for NASA at Kennedy Space Center. LVOS simulates the Saturn launch vehicle and its ground support equipment. The simulator was intended primarily to be used as a launch crew trainer but it is also being used for test procedure and software validation. A NASA/contractor team of engineers and programmers implemented the simulator after the Apollo XI lunar landing during the low activity periods between launches.

  9. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-07

    NASA Photographer Kim Shiflett, left, and Videographer Glenn Benson capture a group photo of the launch team in Firing Room Four of the NASA Kennedy Space Center Launch Control Center (LCC) shortly after the space shuttle Atlantis, STS-135, launched on Friday, July 8, 2011, in Cape Canaveral, Fla. The launch of Atlantis is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  10. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-07

    NASA Kennedy Space Center worker Dwayne Hutcheson sweeps the Launch Control Center (LCC) lobby floor in preparation for the post launch tradition of corn bread and beans after a successful launch of the space shuttle Atlantis from pad 39A on Friday, July 8, 2011, in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  11. Acoustic borehole logging

    SciTech Connect

    Medlin, W.L.; Manzi, S.J.

    1990-10-09

    This patent describes an acoustic borehole logging method. It comprises traversing a borehole with a borehole logging tool containing a transmitter of acoustic energy having a free-field frequency spectrum with at least one characteristic resonant frequency of vibration and spaced-apart receiver, repeatedly exciting the transmitter with a swept frequency tone burst of a duration sufficiently greater than the travel time of acoustic energy between the transmitter and the receiver to allow borehole cavity resonances to be established within the borehole cavity formed between the borehole logging tool and the borehole wall, detecting acoustic energy amplitude modulated by the borehole cavity resonances with the spaced-apart receiver, and recording an amplitude verses frequency output of the receiver in correlation with depth as a log of the borehole frequency spectrum representative of the subsurface formation comprising the borehole wall.

  12. Launch Summary for 1979

    NASA Technical Reports Server (NTRS)

    Vostreys, R. W.

    1980-01-01

    Spacecraft launching for 1979 are identified and listed under the categories of (1) sounding rockets, and (2) artificial Earth satellites and space probes. The sounding rockets section includes a listing of the experiments, index of launch sites and tables of the meanings and codes used in the launch listing.

  13. LAUNCH Health Forum

    NASA Image and Video Library

    2010-10-30

    Tom Kalil, Deputy Director of the White House Office of Science and Technology Policy, opens the LAUNCH: Health forum at NASA's Kennedy Space Center in Florida on Saturday, Oct. 30, 2010. LAUNCH: Health provides a forum to discuss accelerating innovation for a sustainable future. LAUNCH: Health partners include NASA, USAID and Nike. Photo Credit: (NASA/Bill Ingalls)

  14. Launch summary for 1980

    NASA Technical Reports Server (NTRS)

    Vostreys, R. W.

    1981-01-01

    Sounding rockets, artificial Earth satellites, and space probes launched betweeen January 1 and December 31, 1980 are listed. Data tabulated for the rocket launchings show launching site, instruments carried, date of launch, agency rocket identification, sponsoring country, experiment discipline, peak altitude, and the experimenter or institution responsible. Tables for satellites and space probes show COSPAR designation, spacecraft name, country, launch date, epoch date, orbit type, apoapsis, periapsis and inclination period. The functions and responsibilities of the World Data Center and the areas of scientific interest at the seven subcenters are defined. An alphabetical listing of experimenters using the sounding rockets is also provided.

  15. The Rockot launch system

    NASA Astrophysics Data System (ADS)

    Stamerjohanns, G.; Kinnersley, M.

    1999-09-01

    EUROCKOT Launch Services GmbH has been founded by Daimler-Benz Aerospace of Germany and Khrunichev State Research and Production Space Center of Russia to offer world-wide cost effective launch services on the Rockot launch system. The Rockot commercial program is described. Rockot can launch satellites weighing up to 1850 kg into polar and other low earth (LEO) orbits. The Rockot launch vehicle is based on the former Russian SS-19 strategic missile. The first and second stages are inherited from the SS-19, the third stage named Breeze is newly developed and has multiple ignition capability. The Rockot launch system is flight proven. In addition to the currently adapted Rockot launch site Plesetsk for high inclinations, EUROCKOT is in the process to also adapt the Baykonur cosmodrome as their complementary Rockot launch site for lower inclinations. The wide range of Rockot performance is provided. The first commercial launch is foreseen in the middle of 1999. The expected launch capacity for Plesetsk and Baykonur will exceed 10 launches per year. The complete Rockot system including performance is presented.

  16. Electron launching voltage monitor

    DOEpatents

    Mendel, Clifford W.; Savage, Mark E.

    1992-01-01

    An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors.

  17. Electron launching voltage monitor

    DOEpatents

    Mendel, C.W.; Savage, M.E.

    1992-03-17

    An electron launching voltage monitor measures MITL voltage using a relationship between anode electric field and electron current launched from a cathode-mounted perturbation. An electron launching probe extends through and is spaced from the edge of an opening in a first MITL conductor, one end of the launching probe being in the gap between the MITL conductor, the other end being adjacent a first side of the first conductor away from the second conductor. A housing surrounds the launching probe and electrically connects the first side of the first conductor to the other end of the launching probe. A detector detects the current passing through the housing to the launching probe, the detected current being representative of the voltage between the conductors. 5 figs.

  18. Virtual Acoustics

    NASA Astrophysics Data System (ADS)

    Lokki, Tapio; Savioja, Lauri

    The term virtual acoustics is often applied when sound signal is processed to contain features of a simulated acoustical space and sound is spatially reproduced either with binaural or with multichannel techniques. Therefore, virtual acoustics consists of spatial sound reproduction and room acoustics modeling.

  19. Coherent Propagation of Elementary Excitations in Solid ^4He

    NASA Astrophysics Data System (ADS)

    Goodkind, John M.; Ho, Pei-Chun

    1998-03-01

    We have measured the interaction of heat pulses and acoustic pulses propagating along orthogonal paths in solid ^4He with small amounts of ^3He impurities. The interaction is revealed as a variation of the acoustic attenuation, alpha, and velocity, v, as a function of the delay between launching of the heat pulses and the acoustic pulses. alpha and v pass through extreema at delay times corresponding to the relative propagation velocities of the acoustic waves and the excitations created by the heat pulses. The propagation velocities of the various excitations, determined in this way, are between 50 and 150 m/sec and they increase with decreasing temperature. There are two distinct peaks and a long tail at temperatures above about 500 mK indicating that more than one mode is propagating. The peak effect occurs at a different delay time for alpha than for v at temperatures near the attenuation peak (PC HO, I. P. Bindloss, and J. M. Goodkind, J. Low Temp. Phys., November 1997), providing further evidence for more than one type of propagating mode. The sign of the effect reverses as T is decreased and the change of alpha is of opposite sign to that expected from the equilibrium T dependence of alpha. We will discuss the relation of this phenomenon to previous indications of propagating modes in solid ^4He (G.A. Lengua and J. M. Goodkind, J. Low Temp. Phys., 79), 251 (1990)and to the possible Bose-Einstein condensation (PC HO, I. P. Bindloss, and J. M. Goodkind, J. Low Temp. Phys., November 1997).

  20. COSMOS Launch Services

    NASA Astrophysics Data System (ADS)

    Kalnins, Indulis

    2002-01-01

    COSMOS-3M is a two stage launcher with liquid propellant rocket engines. Since 1960's COSMOS has launched satellites of up to 1.500kg in both circular low Earth and elliptical orbits with high inclination. The direct SSO ascent is available from Plesetsk launch site. The very high number of 759 launches and the achieved success rate of 97,4% makes this space transportation system one of the most reliable and successful launchers in the world. The German small satellite company OHB System co-operates since 1994 with the COSMOS manufacturer POLYOT, Omsk, in Russia. They have created the joint venture COSMOS International and successfully launched five German and Italian satellites in 1999 and 2000. The next commercial launches are contracted for 2002 and 2003. In 2005 -2007 COSMOS will be also used for the new German reconnaissance satellite launches. This paper provides an overview of COSMOS-3M launcher: its heritage and performance, examples of scientific and commercial primary and piggyback payload launches, the launch service organization and international cooperation. The COSMOS launch service business strategy main points are depicted. The current and future position of COSMOS in the worldwide market of launch services is outlined.

  1. Antares Rocket Test Launch

    NASA Image and Video Library

    2013-04-21

    The Orbital Sciences Corporation Antares rocket is seen as it launches from Pad-0A of the Mid-Atlantic Regional Spaceport (MARS) at the NASA Wallops Flight Facility in Virginia, Sunday, April 21, 2013. The test launch marked the first flight of Antares and the first rocket launch from Pad-0A. The Antares rocket delivered the equivalent mass of a spacecraft, a so-called mass simulated payload, into Earth's orbit. Photo Credit: (NASA/Bill Ingalls)

  2. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-07

    NASA Administrator Charles Bolden speaks to visitors at the NASA Kennedy Space Center Banana Creek viewing site prior to going to the Launch Control Center (LCC) for the planned launch of the space shuttle Atlantis from pad 39A on Friday, July 8, 2011, in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  3. Launch the Litening Pod!

    DTIC Science & Technology

    2008-02-19

    Launch the LITENING Pod ! EWS Contemporary Issue Paper Submitted by Captain Fausett, Brian M. to Major G.A. Thiele, CG 2 19...TITLE AND SUBTITLE Launch the Litening Pod ! 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e...ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 “Launch the LITENING pod

  4. MAVEN Atlas V Launch

    NASA Image and Video Library

    2013-11-18

    The United Launch Alliance Atlas V rocket with NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft launches from the Cape Canaveral Air Force Station Space Launch Complex 41, Monday, Nov. 18, 2013, Cape Canaveral, Florida. NASA’s Mars-bound spacecraft, the Mars Atmosphere and Volatile EvolutionN, or MAVEN, is the first spacecraft devoted to exploring and understanding the Martian upper atmosphere. Photo Credit: (NASA/Bill Ingalls)

  5. LAUNCH - STS-4 - KSC

    NASA Image and Video Library

    1982-07-06

    S82-33288 (27 June 1982) --- This horizontal view of the space shuttle Columbia captures the flight of water birds disturbed by the activity at launch Pad 39A. Launch occurred at 10:59:59 a.m. (EDT), June 27, 1982. Astronauts Thomas K. Mattingly II and Henry W. Hartsfield Jr. are aboard for NASA's final orbital flight test before launching into a new space era with the first operational flight planned for fall of this year. Photo credit: NASA

  6. MAVEN Atlas V Launch

    NASA Image and Video Library

    2013-11-18

    The United Launch Alliance Atlas V rocket with NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft launches from the Cape Canaveral Air Force Station Space Launch Complex 41, Monday, Nov. 18, 2013, Cape Canaveral, Florida. NASA’s Mars-bound spacecraft, the Mars Atmosphere and Volatile EvolutioN, or MAVEN, is the first spacecraft devoted to exploring and understanding the Martian upper atmosphere. Photo Credit: (NASA/Bill Ingalls)

  7. Expedition 27 Launch

    NASA Image and Video Library

    2010-04-01

    The Soyuz TMA-21 launches from the Baikonur Cosmodrome in Kazakhstan on Tuesday, April 5, 2011 carrying Expedition 27 Soyuz Commander Alexander Samokutyaev, NASA Flight Engineer Ron Garan and Russian Flight Engineer Andrey Borisenko to the International Space Station. The Soyuz, which has been dubbed "Gagarin", is launching one week shy of the 50th anniversary of the launch of Yuri Gagarin from the same launch pad in Baikonur on April 12, 1961 to become the first human to fly in space. Photo Credit: (NASA/Victor Zelentsov)

  8. Expedition 27 Launch

    NASA Image and Video Library

    2011-04-04

    The Soyuz TMA-21 launches from the Baikonur Cosmodrome in Kazakhstan on Tuesday, April 5, 2011 carrying Expedition 27 Soyuz Commander Alexander Samokutyaev, NASA Flight Engineer Ron Garan and Russian Flight Engineer Andrey Borisenko to the International Space Station. The Soyuz, which has been dubbed "Gagarin", is launching one week shy of the 50th anniversary of the launch of Yuri Gagarin from the same launch pad in Baikonur on April 12, 1961 to become the first human to fly in space. Photo Credit: (NASA/Carla Cioffi)

  9. Launch Services Safety Overview

    NASA Technical Reports Server (NTRS)

    Loftin, Charles E.

    2008-01-01

    NASA/KSC Launch Services Division Safety (SA-D) services include: (1) Assessing the safety of the launch vehicle (2) Assessing the safety of NASA ELV spacecraft (S/C) / launch vehicle (LV) interfaces (3) Assessing the safety of spacecraft processing to ensure resource protection of: - KSC facilities - KSC VAFB facilities - KSC controlled property - Other NASA assets (4) NASA personnel safety (5) Interfacing with payload organizations to review spacecraft for adequate safety implementation and compliance for integrated activities (6) Assisting in the integration of safety activities between the payload, launch vehicle, and processing facilities

  10. Antares Rocket Test Launch

    NASA Image and Video Library

    2013-04-21

    NASA Administrator Charles Bolden congratulates the Orbital Sciences Corporation launch team and management in the Range Control Center at the NASA Wallops Flight Facility after the successful launch of the Orbital Sciences Antares rocket from the Mid-Atlantic Regional Spaceport (MARS) in Virginia, Sunday, April 21, 2013. The test launch marked the first flight of Antares and the first rocket launch from Pad-0A. The Antares rocket delivered the equivalent mass of a spacecraft, a so-called mass simulated payload, into Earth's orbit. Photo Credit: (NASA/Bill Ingalls)

  11. GPM: Waiting for Launch

    NASA Image and Video Library

    The Global Precipitation Measurement mission's Core Observatory is poised for launch from the Japan Aerospace Exploration Agency's Tanegashima Space Center, scheduled for the afternoon of Feb. 27, ...

  12. Kestrel balloon launch system

    SciTech Connect

    Newman, M.J.

    1991-10-01

    Kestrel is a high-altitude, Helium-gas-filled-balloon system used to launch scientific payloads in winds up to 20 knots, from small platforms or ships, anywhere over land or water, with a minimal crew and be able to hold in standby conditions. Its major components consist of two balloons (a tow balloon and a main balloon), the main deployment system, helium measurement system, a parachute recovery unit, and the scientific payload package. The main scope of the launch system was to eliminate the problems of being dependent of launching on long airfield runways, low wind conditions, and long launch preparation time. These objectives were clearly met with Kestrel 3.

  13. Acoustic resonance for nonmetallic mine detection

    SciTech Connect

    Kercel, S.W.

    1998-04-01

    The feasibility of acoustic resonance for detection of plastic mines was investigated by researchers at the Oak Ridge National Laboratory`s Instrumentation and Controls Division under an internally funded program. The data reported in this paper suggest that acoustic resonance is not a practical method for mine detection. Representative small plastic anti-personnel mines were tested, and were found to not exhibit detectable acoustic resonances. Also, non-metal objects known to have strong acoustic resonances were tested with a variety of excitation techniques, and no practical non-contact method of exciting a consistently detectable resonance in a buried object was discovered. Some of the experimental data developed in this work may be useful to other researchers seeking a method to detect buried plastic mines. A number of excitation methods and their pitfalls are discussed. Excitation methods that were investigated include swept acoustic, chopped acoustic, wavelet acoustic, and mechanical shaking. Under very contrived conditions, a weak response that could be attributed to acoustic resonance was observed, but it does not appear to be practical as a mine detection feature. Transfer properties of soil were investigated. Impulse responses of several representative plastic mines were investigated. Acoustic leakage coupling, and its implications as a disruptive mechanism were investigated.

  14. Expedition 24 Launch Day

    NASA Image and Video Library

    2010-06-14

    Expedition 24 NASA Flight Engineer Shannon Walker has her Russian Sokol suit prepared for launch by technicians at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Tuesday, June 15, 2010. Walker, Soyuz Commander Fyodor Yurchikhin and Flight Engineer Doug Wheelock launched in their Soyuz TMA-19 rocket from the Baikonur Cosmodrome in Kazakhstan on Wednesday, June 16, 2010. (Photo Credit: NASA/Carla Cioffi)

  15. Expedition 24 Launch Day

    NASA Image and Video Library

    2010-06-14

    Expedition 24 NASA Flight Engineer Doug Wheelock, center, has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Tuesday, June 15, 2010. Wheelock, Soyuz Commander Fyodor Yurchikhin and Flight Engineer Shannon Walker launched in their Soyuz TMA-19 rocket from the Baikonur Cosmodrome in Kazakhstan on Wednesday, June 16, 2010. (Photo Credit: NASA/Carla Cioffi)

  16. Expedition 24 Launch Day

    NASA Image and Video Library

    2010-06-14

    Expedition 24 NASA Flight Engineer Doug Wheelock has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Tuesday, June 15, 2010. Wheelock, Soyuz Commander Fyodor Yurchikhin and Flight Engineer Shannon Walker launched in their Soyuz TMA-19 rocket from the Baikonur Cosmodrome in Kazakhstan on Wednesday, June 16, 2010. (Photo Credit: NASA/Carla Cioffi)

  17. Saturn IB Launch

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The Saturn IB launch vehicle lifting off from Launch Complex 39B at 9:01 a.m. EST. The Skylab 4 astronauts Gerald P. Carr, Dr. Edward G. Gibson, and William R. Pogue, were onboard for the third and final mission to the orbiting space station.

  18. Saturn IB Launch Summary

    NASA Technical Reports Server (NTRS)

    1973-01-01

    This chart provides a launch summary of the Saturn IB launch vehicle as of 1973. Developed by the Marshall Space Flight Center (MSFC) as an interim vehicle in MSFC's 'building block' approach to the Saturn rocket development, the Saturn IB utilized Saturn I technology to further develop and refine the larger boosters and the Apollo spacecraft capabilities required for the marned lunar missions.

  19. Expedition 8 Launch Briefing

    NASA Image and Video Library

    2003-10-15

    Expedition 8 Soyuz Commander and Flight Engineer Alexander Kaleri and European Space Agency astronaut Pedro Duque of Spain are briefed on launch procedures from a Russian trainer at their crew quarters in Baikonur, Kazakhstan, Wednesday, Oct. 15, 2003 as they prepare for launch Oct. 18 in a Soyuz TMA-3 vehicle to the International Space Station. Photo Credit (NASA/Bill Ingalls)

  20. Launch Collision Probability

    NASA Technical Reports Server (NTRS)

    Bollenbacher, Gary; Guptill, James D.

    1999-01-01

    This report analyzes the probability of a launch vehicle colliding with one of the nearly 10,000 tracked objects orbiting the Earth, given that an object on a near-collision course with the launch vehicle has been identified. Knowledge of the probability of collision throughout the launch window can be used to avoid launching at times when the probability of collision is unacceptably high. The analysis in this report assumes that the positions of the orbiting objects and the launch vehicle can be predicted as a function of time and therefore that any tracked object which comes close to the launch vehicle can be identified. The analysis further assumes that the position uncertainty of the launch vehicle and the approaching space object can be described with position covariance matrices. With these and some additional simplifying assumptions, a closed-form solution is developed using two approaches. The solution shows that the probability of collision is a function of position uncertainties, the size of the two potentially colliding objects, and the nominal separation distance at the point of closest approach. ne impact of the simplifying assumptions on the accuracy of the final result is assessed and the application of the results to the Cassini mission, launched in October 1997, is described. Other factors that affect the probability of collision are also discussed. Finally, the report offers alternative approaches that can be used to evaluate the probability of collision.

  1. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-08

    Space shuttle Atlantis is seen as it launches from pad 39A on Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  2. Acoustic Neuroma

    MedlinePlus

    An acoustic neuroma is a benign tumor that develops on the nerve that connects the ear to the brain. ... can press against the brain, becoming life-threatening. Acoustic neuroma can be difficult to diagnose, because the ...

  3. KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  4. KENNEDY SPACE CENTER, FLA. - Research team members work with acoustic cable during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Research team members work with acoustic cable during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  5. KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge as others stand by in a watercraft during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

    NASA Image and Video Library

    2003-08-18

    KENNEDY SPACE CENTER, FLA. - Research team members roll out acoustic cable to the water's edge as others stand by in a watercraft during underwater acoustic research being conducted in the Launch Complex 39 turn basin. Several government agencies, including NASA, NOAA, the Navy, the Coast Guard, and the Florida Fish and Wildlife Commission are involved in the testing. The research involves demonstrations of passive and active sensor technologies, with applications in fields ranging from marine biological research to homeland security. The work is also serving as a pilot project to assess the cooperation between the agencies involved. Equipment under development includes a passive acoustic monitor developed by NASA’s Jet Propulsion Laboratory, and mobile robotic sensors from the Navy’s Mobile Diving and Salvage Unit.

  6. Acoustic Seaglider

    DTIC Science & Technology

    2008-03-07

    a national naval responsibility. Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial...problem and acoustic navigation and communications within the context of distributed autonomous persistent undersea surveillance sensor networks...Acoustic sensors on mobile, autonomous platforms will enable basic research topics on temporal and spatial coherence and the description of ambient

  7. Acoustic seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  8. Acoustic Seal

    NASA Technical Reports Server (NTRS)

    Steinetz, Bruce M. (Inventor)

    2006-01-01

    The invention relates to a sealing device having an acoustic resonator. The acoustic resonator is adapted to create acoustic waveforms to generate a sealing pressure barrier blocking fluid flow from a high pressure area to a lower pressure area. The sealing device permits noncontacting sealing operation. The sealing device may include a resonant-macrosonic-synthesis (RMS) resonator.

  9. Air Coupled Acoustic Thermography (ACAT) Inspection Technique

    NASA Technical Reports Server (NTRS)

    Zalameda, Joseph; Winfree, William P.; Yost, William T.

    2007-01-01

    The scope of this effort is to determine the viability of a new heating technique using a noncontact acoustic excitation source. Because of low coupling between air and the structure, a synchronous detection method is employed. Any reduction in the out of plane stiffness improves the acoustic coupling efficiency and as a result, defective areas have an increase in temperature relative to the surrounding area. Hence a new measurement system, based on air-coupled acoustic energy and synchronous detection is presented. An analytical model of a clamped circular plate is given, experimentally tested, and verified. Repeatability confirms the technique with a measurement uncertainty of plus or minus 6.2 percent. The range of frequencies used was 800-2,000 Hertz. Acoustic excitation and consequent thermal detection of flaws in a helicopter blade is examined and results indicate that air coupled acoustic excitation enables the detection of core damage in sandwich honeycomb structures.

  10. Air Coupled Acoustic Thermography (acat) Inspection Technique

    NASA Astrophysics Data System (ADS)

    Zalameda, J. N.; Winfree, W. P.; Yost, W. T.

    2008-02-01

    The scope of this effort is to determine the viability of a new heating technique using a noncontact acoustic excitation source. Because of low coupling between air and the structure, a synchronous detection method is employed. Any reduction in the out of plane stiffness improves the acoustic coupling efficiency and as a result, defective areas have an increase in temperature relative to the surrounding area. Hence a new measurement system, based on air-coupled acoustic energy and synchronous detection is presented. An analytical model of a clamped circular plate is given, experimentally tested, and verified. Repeatability confirms the technique with a measurement uncertainty of +/-6.2 percent. The range of frequencies used was 800-2,000 Hertz. Acoustic excitation and consequent thermal detection of flaws in a helicopter blade is examined and results indicate that air coupled acoustic excitation enables the detection of core damage in sandwich honeycomb structures.

  11. 65. DETAIL OF ASSISTANT LAUNCH CONTROLLER AND LAUNCH CONTROLLER PANELS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    65. DETAIL OF ASSISTANT LAUNCH CONTROLLER AND LAUNCH CONTROLLER PANELS LOCATED NEAR CENTER OF SLC-3E CONTROL ROOM. NOTE 30-CHANNEL COMMUNICATIONS PANELS. PAYLOAD ENVIRONMENTAL CONTROL AND MONITORING PANELS (LEFT) AND LAUNCH OPERATORS PANEL (RIGHT) IN BACKGROUND. - Vandenberg Air Force Base, Space Launch Complex 3, Launch Operations Building, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

  12. Antares Rocket Test Launch

    NASA Image and Video Library

    2013-04-21

    NASA Deputy Administrator Lori Garver and other guests react after having watched the successful launch of the Orbital Sciences Corporation Antares rocket from the Mid-Atlantic Regional Spaceport (MARS) at the NASA Wallops Flight Facility in Virginia, Sunday, April 21, 2013. The test launch marked the first flight of Antares and the first rocket launch from Pad-0A. The Antares rocket delivered the equivalent mass of a spacecraft, a so-called mass simulated payload, into Earth's orbit. Photo Credit: (NASA/Bill Ingalls)

  13. Antares Rocket Test Launch

    NASA Image and Video Library

    2013-04-21

    NASA Administrator Charles Bolden and NASA Deputy Administrator Lori Garver and other guests react after having watched the successful launch of the Orbital Sciences Corporation Antares rocket from the Mid-Atlantic Regional Spaceport (MARS) at the NASA Wallops Flight Facility in Virginia, Sunday, April 21, 2013. The test launch marked the first flight of Antares and the first rocket launch from Pad-0A. The Antares rocket delivered the equivalent mass of a spacecraft, a so-called mass simulated payload, into Earth's orbit. Photo Credit: (NASA/Bill Ingalls)

  14. STS-135 Launch Day

    NASA Image and Video Library

    2011-07-07

    NASA Chief, Astronaut Office, Johnson Space Center Peggy Whitson deals cards during a traditional game that is played at the NASA Kennedy Space Center Operations and Checkout Building with the shuttle crew prior to them leaving for the launch pad, on Friday, July 8, 2011 in Cape Canaveral, Fla. The point of the game is that the commander must use up all his or her bad luck before launch, so the crew can only leave for the pad after the commander loses. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

  15. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-08

    Space shuttle Atlantis is seen through the window of a Shuttle Training Aircraft (STA) as it launches from launch pad 39A at Kennedy Space Center on the STS-135 mission, Friday, July 8, 2011 in Cape Canaveral, Fla. Atlantis launched on the final flight of the shuttle program on a 12-day mission to the International Space Station. The STS-135 crew will deliver the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Dick Clark)

  16. Ultrasonic spectrum in Fibonacci acoustic superlattices

    NASA Astrophysics Data System (ADS)

    Zhu, Yong-Yuan; Ming, Nai-Ben; Jiang, Wen-Hua

    1989-10-01

    A new type of superlattice, a Fibonacci acoustic superlattice, is presented. Its ultrasonic spectrum, which is excited by the piezoelectric effect, has been studied theoretically and experimentally. The results are in good agreement with each other.

  17. Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions

    NASA Technical Reports Server (NTRS)

    Strutzenberg, Louise L.; Liever, Peter A.

    2011-01-01

    This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.

  18. Launch of Juno!

    NASA Image and Video Library

    An Atlas V rocket lofted the Juno spacecraft toward Jupiter from Space Launch Complex-41. The 4-ton Juno spacecraft will take five years to reach Jupiter on a mission to study its structure and dec...

  19. Anchor Trial Launch

    Cancer.gov

    NCI has launched a multicenter phase III clinical trial called the ANCHOR Study -- Anal Cancer HSIL (High-grade Squamous Intraepithelial Lesion) Outcomes Research Study -- to determine if treatment of HSIL in HIV-infected individuals can prevent anal canc

  20. Genomic Data Commons launches

    Cancer.gov

    The Genomic Data Commons (GDC), a unified data system that promotes sharing of genomic and clinical data between researchers, launched today with a visit from Vice President Joe Biden to the operations center at the University of Chicago.

  1. Hi-C Launch

    NASA Image and Video Library

    The High resolution Coronal Imager (Hi-C) was launched on a NASA Black Brant IX two-stage rocket from White Sands Missile Range in New Mexico July 11, 2012. The experiment reached a maximum velocit...

  2. Launch - STS-6 - KSC

    NASA Image and Video Library

    1983-04-12

    S83-30222 (4 April 1983) --- The second reusable spacecraft in history successfully launches from Launch Pad 39A at 1:30:00:88 p.m. (EST) on April 4, 1983, and heads for its history making five-day mission in Earth orbit. The space shuttle Challenger, its two solid rocket boosters (SRB), and a new lightweight?external fuel tank were captured on film by an automatically-tripped camera in a protected station nearer to the launch pad than human beings are able to be at launch time. Onboard the spacecraft are astronauts Paul J. Wietz, Karol J. Bobko, Dr. Story Musgrave and Donald H. Peterson. Photo credit: NASA

  3. First Accessible Boat Launch

    EPA Pesticide Factsheets

    This is a story about how the Northwest Indiana urban waters partnership location supported the process to create and open the first handicap accessible canoe and kayak launch in the state of Indiana.

  4. IRVE 3 Launch

    NASA Image and Video Library

    The Inflatable Reentry Vehicle Experiment, or IRVE-3, launched on July 23, 2012, from NASA's Wallops Flight Facility. The purpose of the IRVE-3 test was to show that a space capsule can use an infl...

  5. GPM Launch Coverage

    NASA Image and Video Library

    A Japanese H-IIA rocket with the NASA-Japan Aerospace Exploration Agency (JAXA) Global Precipitation Measurement (GPM) Core Observatory aboard, launched from the Tanegashima Space Center in Japan o...

  6. NASA Now: Glory Launch

    NASA Image and Video Library

    In this episode of NASA Now, Dr. Hal Maring joins us to explain why the upcoming launch of the Glory satellite is so important to further our understanding of climate change. He also will speak on ...

  7. Cryogenic exciter

    DOEpatents

    Bray, James William [Niskayuna, NY; Garces, Luis Jose [Niskayuna, NY

    2012-03-13

    The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

  8. Acoustic transmission through a fuselage sidewall

    NASA Technical Reports Server (NTRS)

    Wilby, J. F.; Scharton, T. D.

    1973-01-01

    A definition is given of an idealized fuselage sidewall structure and a simplified analytical model for determining acoustical transmission from the exterior to the interior of a fuselage was constructed. The representation of the sidewall structure chosen for the analytical model excludes complicating effects such as cabin pressurization, acoustic transmission through windows or door seal leaks, aerodynamic excitation, and structural vibration excitation of the fuselage skin.

  9. ACOUSTIC FORMING FOR ENHANCED DEWATERING AND FORMATION

    SciTech Connect

    Cyrus K Aidun

    2007-11-30

    The next generation of forming elements based on acoustic excitation to increase drainage and enhances formation both with on-line control and profiling capabilities has been investigated in this project. The system can be designed and optimized based on the fundamental experimental and computational analysis and investigation of acoustic waves in a fiber suspension flow and interaction with the forming wire.

  10. Levitation With a Single Acoustic Driver

    NASA Technical Reports Server (NTRS)

    Barmatz, M. B.; Gaspar, M. S.; Allen, J. L.

    1986-01-01

    Pair of reports describes acoustic-levitation systems in which only one acoustic resonance mode excited, and only one driver needed. Systems employ levitation chambers of rectangular and cylindrical geometries. Reports first describe single mode concept and indicate which modes used to levitate sample without rotation. Reports then describe systems in which controlled rotation of sample introduced.

  11. Vertical Launch Alignment Transfer Apparatus.

    DTIC Science & Technology

    A launch mechanism for vertically launching missiles carried in launch tubes disposed in a pod . The launch mechanism includes apparatus for... pod and v-groove elements are secured in the launch tubes and oriented to the northfinder. Rods are secured on opposite sides of each missile and are

  12. 33. Launch Control Center, close view of launch key inserted ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. Launch Control Center, close view of launch key inserted in the launch panel. Lyon - Whiteman Air Force Base, Oscar O-1 Minuteman Missile Alert Facility, Southeast corner of Twelfth & Vendenberg Avenues, Knob Noster, Johnson County, MO

  13. Experiences with Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Dumbacher, Daniel L.

    2006-01-01

    The presentation "NASA Experience with Launch Vehicles" is a compilation of Mr. Dumbacher's career experiences with the Space Shuttle Program, the Delta - Clipper Experimental flight test project, the X-33 demonstrator project, and recent experiences with the Orbital Spaceplane Program agd the current NASA effort on Exploration Launch Systems. Mr. Dumbacher will discuss his personal experiences and provide lessons learned from each program. The accounts provided by Mr. Dumbacher are his own and do not necessarily represent the official NASA position.

  14. STS-130 Launch Attempt

    NASA Image and Video Library

    2010-02-07

    NASA Associate Administrator for Space Operations Bill Gerstenmaier, center, reacts to an updated weather report during the countdown of the launch of the space shuttle Endeavour and the start of the STS-130 mission at NASA Kennedy Space Center in Cape Canaveral, Fla. on Sunday Feb. 7, 2010. Space shuttle Endeavour's launch attempt was scrubbed due to a low cloud ceiling over Kennedy Space Center. Photo Credit: (NASA/Bill Ingalls)

  15. STS-132 Launch Tweetup

    NASA Image and Video Library

    2010-05-12

    Jon Cowart @Rocky_Sci, orbiter engineering manager, Space Shuttle Program, interacts with Tweetup participant, Jen Vargas, @jenvargus, as he speaks to participants at the two-day STS-132 Launch Tweetup at Kennedy Space Center, Thursday, May 13, 2010, in Cape Canaveral, Fla. NASA Twitter followers in attendance will have the opportunity to take a tour of NASA's Kennedy Space Center, view the space shuttle launch and speak with shuttle technicians, engineers, astronauts and managers. Photo Credit: (NASA/Paul E. Alers)

  16. Expedition 23 Launch Day

    NASA Image and Video Library

    2010-04-01

    Expedition 23 Flight Engineer Mikhail Kornienko of the Russia has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Kornienko and fellow Expedition 23 crewmembers Soyuz Commander Alexander Skvortsov and NASA Flight Engineer Tracy Caldwell Dyson of the U.S. launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

  17. Expedition 23 Launch Day

    NASA Image and Video Library

    2010-04-01

    Expedition 23 Soyuz Commander Alexander Skvortsov has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Skvortsov and fellow Expedition 23 crewmembers Flight Engineer Mikhail Kornienko of the Russia and NASA Flight Engineer Tracy Caldwell Dyson of the U.S. launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

  18. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 Flight Engineer Soichi Noguchi of Japan has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Sunday, Dec. 20, 2009. Soichi and fellow Expedition 22 crew members NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia launched in their Soyuz TMA-17 rocket from the Baikonur Cosmodrome in Kazakhstan on Monday, Dec. 21, 2009. (Photo Credit: NASA/Bill Ingalls)

  19. Expedition 23 Launch Day

    NASA Image and Video Library

    2010-04-01

    Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson, left, talks with Soyuz Commander Alexander Skvortsov of Russia, while Flight Engineer Mikhail Kornienko of Russia has his Russian Sokol suit prepared for launch at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. The Expedition 23 crew members launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. (Photo Credit: NASA/Bill Ingalls)

  20. Expedition 23 Launch Day

    NASA Image and Video Library

    2010-04-01

    Expedition 23 NASA Flight Engineer Tracy Caldwell Dyson of the U.S. has her Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, April 2, 2010. Caldwell Dyson and fellow Expedition 23 crew members Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko of Russia launched in their Soyuz TMA-18 rocket from the Baikonur Cosmodrome in Kazakhstan on Friday, April 2, 2010. Photo Credit: (NASA/Carla Cioffi)

  1. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 NASA Flight Engineer Scott Kelly of the U.S. has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Friday, Oct. 8, 2010. Kelly and fellow Expedition 25 crew members Soyuz Commander Alexander Kaleri and Flight Engineer Oleg Skripochka launched in their Soyuz TMA-01M at 5:10 a.m. Friday morning. (Photo Credit: NASA/Carla Cioffi)

  2. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    The Soyuz TMA-01M rocket launches from the Baikonur Cosmodrome in Kazakhstan on Friday, October 8, 2010 carrying Expedition 25 Soyuz Commander Alexander Kaleri of Russia, NASA Flight Engineer Scott J. Kelly and Russian Flight Engineer Oleg Skripochka to the International Space Station. Their Soyuz TMA-01M rocket launched at 5:10 a.m Kazakhstan time. (Photo Credit: NASA/Carla Cioffi)

  3. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 NASA Flight Engineer Scott Kelly of the U.S. has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Kazakhstan, Friday, Oct. 8, 2010. Kelly and fellow Expedition 25 crew members Soyuz Commander Alexander Kaleri and Flight Engineer Oleg Skripochka launched in their Soyuz TMA-01M at 5:10 a.m. Friday morning. (Photo Credit: NASA/Carla Cioffi)

  4. STS-64 launch view

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Passing through some of the trailer clouds of an overcast sky which temporarily postponed its launch, the Space Shuttle Discovery heads for its 19th Earth orbital flight. Several kilometers away, astronaut John H. Casper, Jr., who took this picture, was piloting the Shuttle Training Aircraft (STA) from which the launch and landing area weather was being monitored. Onboard Discovery were astronauts Richard N. Richards, L. Blaine Hammond, Jr., Mark C. Lee, Carl J. Meade, Susan J. Helms, and Jerry M. Linenger.

  5. Orion EFT-1 Launch

    NASA Image and Video Library

    2014-12-05

    A Delta IV Heavy rocket lifts off from Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida carrying NASA's Orion spacecraft on an unpiloted flight test to Earth orbit. Liftoff was at 7:05 a.m. EST. During the two-orbit, four-and-a-half hour mission, engineers will evaluate the systems critical to crew safety, the launch abort system, the heat shield and the parachute system.

  6. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-21

    Expedition 22 Soyuz Commander Oleg Kotov of Russia, left, NASA Flight Engineer Timothy J. Creamer of the U.S., back center, and Flight Engineer Soichi Noguchi of Japan are walked from their bus to the soyuz rocket at the launch pad at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Monday, Dec. 21, 2009. Kotov, Creamer and Noguchi launched in their Soyuz TMA-17 rocket from the Baikonur Cosmodrome in Kazakhstan on Monday, Dec. 21, 2009. (Photo Credit: NASA/Bill Ingalls)

  7. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 Soyuz Commander Oleg Kotov of Russia, center, has his Russian Sokol suit prepared for launch while NASA Flight Engineer Timothy J. Creamer of the U.S., left, and Flight Engineer Soichi Noguchi of Japan wait at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Sunday, Dec. 20, 2009. The Expedition 22 crew members launched in their Soyuz TMA-17 rocket from the Baikonur Cosmodrome in Kazakhstan on Monday, Dec. 21, 2009. (Photo Credit: NASA/Bill Ingalls)

  8. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S. has his Russian Sokol suit prepared for launch by a technician at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Sunday, Dec. 20, 2009. Creamer and fellow Expedition 22 crew members, Soyuz Commander Oleg Kotov of Russia, Flight Engineer Soichi Noguchi of Japan launched in their Soyuz TMA-17 rocket from the Baikonur Cosmodrome in Kazakhstan on Monday, Dec. 21, 2009. (Photo Credit: NASA/Bill Ingalls)

  9. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S., left, talks with Soyuz Commander Oleg Kotov of Russia, right, while Flight Engineer Soichi Noguchi of Japan has his Russian Sokol suit prepared for launch at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Sunday, Dec. 20, 2009. The Expedition 22 crew members launched in their Soyuz TMA-17 rocket from the Baikonur Cosmodrome in Kazakhstan on Monday, Dec. 21, 2009. (Photo Credit: NASA/Bill Ingalls)

  10. Magnetic Launch Assist

    NASA Technical Reports Server (NTRS)

    Perez, Jose

    2000-01-01

    The objectives of this program are to: (1) To develop a safe, reliable, inexpensive, and minimum operation launch assist system for sending payloads into orbit using ground powered, magnetic suspension and propulsion technologies; (2) Improve safety, reliability, operability for third generation Reusable Launch Vehicles (RLV); (3) Reduce vehicle weight and increase payload capacity; and (4) Support operational testing of Rocket Based Combine Cycle (RBCC) engines.

  11. STS-132 Launch Tweetup

    NASA Image and Video Library

    2010-05-12

    Kendal Van Dyke, a database professional that is followed on Twitter @twitter.com/sqldba, takes part in the two-day STS-132 Launch Tweetup at Kennedy Space Center, Thursday, May 13, 2010, in Cape Canaveral, Fla. NASA Twitter followers in attendance will have the opportunity to take a tour of NASA's Kennedy Space Center, view the space shuttle launch and speak with shuttle technicians, engineers, astronauts and managers. Photo Credit: (NASA/Paul E. Alers)

  12. Expedition 8 Launch Day

    NASA Image and Video Library

    2003-10-18

    Technicians conduct a leak check on the spacesuit of Expedition 8 Soyuz Commander Alexander Kaleri at the Baikonur Cosmodrome, Saturday, Oct. 18, 2003, prior to his departure for the launch pad with Expedition 8 Commander and NASA Science Officer Mike Foale and European Space Agency astronaut Pedro Duque of Spain. The trio were launched on a Soyuz TMA-3 vehicle to the International Space Station, arriving on Oct. 20. Photo Credit (NASA/Bill Ingalls)

  13. Expedition 8 Launch Day

    NASA Image and Video Library

    2003-10-18

    Technicians conduct a leak check on the spacesuit of European Space Agency astronaut Pedro Duque of Spain at the Baikonur Cosmodrome, Saturday, Oct. 18, 2003, prior to his departure for the launch pad with Expedition 8 Commander and NASA Science Officer Mike Foale and Soyuz Commander Alexander Kaleri. The trio were launched on a Soyuz TMA-3 vehicle to the International Space Station, arriving on Oct. 20. Photo Credit (NASA/Bill Ingalls)

  14. Expedition 8 Launch Day

    NASA Image and Video Library

    2003-10-18

    Expedition 8 Commander and NASA Science Officer Michael Foale completes suiting up at the Baikonur Cosmodrome in Kazakhstan, Saturday, Oct. 18, 2003, prior to departing for the launch pad with Expedition 8 Soyuz Commander Alexander Kaleri and European Space Agency astronaut Pedro Duque of Spain. The trio were launched on the Soyuz TMA-3 vehicle to the International Space Station, arriving on Oct. 20. Photo Credit (NASA/Bill Ingalls)

  15. Launch Vehicle Communications

    NASA Technical Reports Server (NTRS)

    Welch, Bryan; Greenfeld, Israel

    2005-01-01

    As the National Aeronautics and Space Administration's (NASA) planning for updated launch vehicle operations progresses, there is a need to consider improved methods. This study considers the use of phased array antennas mounted on launch vehicles and transmitting data to either NASA's Tracking and Data Relay Satellite System (TDRSS) satellites or to the commercial Iridium, Intelsat, or Inmarsat communications satellites. Different data rate requirements are analyzed to determine size and weight of resulting antennas.

  16. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-08

    Guests look on from the terrace of Operations Support Building II as space shuttle Atlantis launches from launch pad 39A on the STS-135 mission Friday, July 8, 2011, at Kennedy Space Center in Cape Canaveral, Fla. Atlantis and its crew will deliver to the International Space Station the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Carla Cioffi)

  17. STS-135 Atlantis Launch

    NASA Image and Video Library

    2011-07-08

    Space shuttle Atlantis, STS-135, launches skyward on a 12-day mission to the International Space Station (ISS), Friday, July 8, 2011, at NASA's Kennedy Space Center in Cape Canaveral, Fla. The launch of Atlantis is the final flight of the shuttle program and will carry the Raffaello multipurpose logistics module containing supplies and spare parts for the space station. Photo Credit: (NASA/Paul E. Alers)

  18. Orion EFT-1 Launch

    NASA Image and Video Library

    2014-12-05

    A Delta IV Heavy rocket roars to life at Space Launch Complex 37 at Cape Canaveral Air Force Station in Florida. The launch vehicle is carrying NASA's Orion spacecraft on an unpiloted flight test to Earth orbit. Liftoff was at 7:05 a.m. EST. The flight will send Orion 3,600 miles in altitude beyond the Earth's surface on a four-and-a-half hour mission.

  19. STS-132 Launch Tweetup

    NASA Image and Video Library

    2010-05-12

    Ron Woods, an equipment specialist, who has been a space suit designer from Mercury to now speaks to participants at the two-day STS-132 Launch Tweetup at Kennedy Space Center, Thursday, May 13, 2010, in Cape Canaveral, Fla. NASA Twitter followers in attendance will have the opportunity to take a tour of NASA's Kennedy Space Center, view the space shuttle launch and speak with shuttle technicians, engineers, astronauts and managers. Photo Credit: (NASA/Paul E. Alers)

  20. Electromagnetic Launch to Space

    NASA Astrophysics Data System (ADS)

    McNab, I. R.

    Many advances in electromagnetic (EM) propulsion technology have occurred in recent years. Linear motor technology for low-velocity and high-mass applications is being developed for naval catapults. Such technology could serve as the basis for a first-stage booster launch--as suggested by the US National Aeronautics and Space Administration (NASA) in the Maglifter concept. Using railguns, laboratory experiments have demonstrated launch velocities of 2-3 km/s and muzzle energies > 8 MJ. The extension of this technology to the muzzle velocities ( 7500 m/s) and energies ( 10 GJ) needed for the direct launch of payloads into orbit is very challenging but may not be impossible. For launch to orbit, even long launchers (> 1000 m) would need to operate at accelerations > 1000 G to reach the required velocities, so it would only be possible to launch rugged payloads, such as fuel, water, and materiel. Interest is being shown in such concepts by US, European, Russian, and Chinese researchers. An intermediate step proposed in France could be to launch payloads to sounding rocket altitudes for ionospheric research.

  1. Study of surface plasmons with a scanning acoustic microscope

    SciTech Connect

    Bereiter-Hahn, J; Blase, C; Lozovik, Yurii E; Nazarov, Maksim M; Shkurinov, A P

    2003-05-31

    A new technique for investigating the surface plasmons by means of a scanning acoustic microscope is proposed. Within this technique, the surface electromagnetic wave (plasmon polariton) is excited by laser radiation on one side of a metal film, while a scanning acoustic microscope excites surface acoustic waves on the other side of the film. Obtained for the first time, the acoustic images of plasmons, propagating on the grating surface, demonstrate the possibility of studying the plasmon wave field distribution by means of a scanning acoustic microscope. (nonlinear optical phenomena)

  2. Method and apparatus for generating acoustic energy

    DOEpatents

    Guerrero, Hector N.

    2002-01-01

    A method and apparatus for generating and emitting amplified coherent acoustic energy. A cylindrical transducer is mounted within a housing, the transducer having an acoustically open end and an acoustically closed end. The interior of the transducer is filled with an active medium which may include scattering nuclei. Excitation of the transducer produces radially directed acoustic energy in the active medium, which is converted by the dimensions of the transducer, the acoustically closed end thereof, and the scattering nuclei, to amplified coherent acoustic energy directed longitudinally within the transducer. The energy is emitted through the acoustically open end of the transducer. The emitted energy can be used for, among other things, effecting a chemical reaction or removing scale from the interior walls of containment vessels.

  3. GPM Core Observatory Launch Animation

    NASA Image and Video Library

    This animation depicts the launch of the Global Precipitation Measurement (GPM) Core Observatory satellite from Tanegashima Space Center, Japan. The launch is currently scheduled for Feb. 27, 2014....

  4. Acoustic Model Testing Chronology

    NASA Technical Reports Server (NTRS)

    Nesman, Tom

    2017-01-01

    Scale models have been used for decades to replicate liftoff environments and in particular acoustics for launch vehicles. It is assumed, and analyses supports, that the key characteristics of noise generation, propagation, and measurement can be scaled. Over time significant insight was gained not just towards understanding the effects of thruster details, pad geometry, and sound mitigation but also to the physical processes involved. An overview of a selected set of scale model tests are compiled here to illustrate the variety of configurations that have been tested and the fundamental knowledge gained. The selected scale model tests are presented chronologically.

  5. Modeling the acoustic excitation of a resonator

    NASA Astrophysics Data System (ADS)

    Mandre, Shreyas; Mahadevan, Lakshminarayanan

    2007-11-01

    The sounding of a beverage bottle when blown on is a familiar but very little understood phenomenon. A very similar mechanism is used by musical wind instruments, like organ pipes and flutes, for sound production. This phenomenon falls under the general umbrella of flow induced oscillations and is representative of a more generic mechanism. The modeling of this phenomenon essentially involves two components. The first is the resonator, which bears the oscillations and this component is very well understood. The resonator, however, needs an external energy input to sustain the oscillations, which is provided by the jet of air blown. The dynamics of the jet and its interaction with the resonator is the primary focus of this talk. In particular, we provide a linearized model based on first principles to explain the feedback of energy from the jet to the resonator and compare the predictions with experimental results.

  6. Development of a launch vibration isolation system

    NASA Astrophysics Data System (ADS)

    Edberg, Donald L.; Johnson, Conor D.; Davis, L. Porter; Fosness, Eugene R.

    1997-05-01

    The U.S. Air Force's Phillips Laboratory has sponsored several programs to isolate payloads from mechanical vibrations during launch. This paper details a program called LVIS (for launch vibration isolation system). LVIS's goals are to reduce the rms accelerations felt by an isolated payload by a factor of 5 compared to an unisolated payload while using minimal launch vehicle services, fitting within existing payload attach fittings' dimension and mass envelopes, and providing fail- safe operation. The LVIS system must provide axial isolation while at the same time not allowing its host spacecraft to 'rattle' too much and make contact with the launch vehicle's external payload fairing, which is present to protect against heat, aerodynamic, and acoustic loads. This challenging set of goals will be accomplished using an innovative suspension system specially designed to be relatively soft in the vertical and lateral directions and stiff in the rotational directions to prevent payload fairing contact. An overview of the LVIS design and predicted performance is given.

  7. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  8. Ares Launch Vehicles Overview

    NASA Technical Reports Server (NTRS)

    Vanhooser, Teresa

    2009-01-01

    Since 2005, the Ares Projects have been building the nation s next generation of crew and cargo launch vehicles. As part of the Constellation Program, the Ares vehicles will enable astronauts in the Orion crew exploration vehicle and Altair lunar lander to reach the Moon and beyond. These vehicles draw upon hardware and experienced developed over 50 years of exploration, while also incorporating technology and management practices from today. Ares is concentrating on building the Ares I crew launch vehicle to ensure America s continued ability to send crews to the International Space Station. Progress has been made on design, fabrication, and testing for the first stage, upper stage, upper stage engine, and integrated vehicle. This presentation will provide an overview of the Ares launch vehicles architecture, milestone progress, and top project risks.

  9. STS-133 launch

    NASA Image and Video Library

    2011-02-24

    STS133-S-067 (24 Feb. 2011) --- In Firing Room 4 of the Launch Control Center at NASA's Kennedy Space Center in Florida, NASA's Discovery Flow Director Stephanie Stilson, left, STS-133 Assistant Shuttle Launch Director and lead NASA Test Director Charlie Blackwell-Thompson and Shuttle Launch Director Mike Leinbach watch space shuttle Discovery head toward Earth orbit on the STS-133 mission to the International Space Station. Discovery and its six-member crew are on a mission to deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. Discovery is making its 39th mission and is scheduled to be retired following STS-133. This is the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA or National Aeronautics and Space Administration

  10. STS-135 Launch Day

    NASA Image and Video Library

    2011-07-07

    NASA Chief, Astronaut Office, Johnson Space Center Peggy Whitson, center, STS-135 Astronauts, Rex Walheim, left, and Commander Chris Ferguson are seen as the entire crew plays a traditional card game at the NASA Kennedy Space Center Operations and Checkout Building prior to them leaving for the launch pad, on Friday, July 8, 2011 in Cape Canaveral, Fla. The point of the game is that the commander must use up all his or her bad luck before launch, so the crew can only leave for the pad after the commander loses. The launch of Atlantis, STS-135, is the final flight of the shuttle program, a 12-day mission to the International Space Station. Photo Credit: (NASA/Jerry Ross)

  11. Antares Rocket Test Launch

    NASA Image and Video Library

    2013-04-21

    NASA Deputy Administrator Lori Garver talks with CEO and President of Orbital Sciences Corporation David Thompson, left, Executive Vice President and Chief Technical Officer, Orbital Sciences Corporation Antonio Elias, second from left, and Executive Director, Va. Commercial Space Flight Authority Dale Nash, background, in the Range Control Center at the NASA Wallops Flight Facility after the successful launch of the Orbital Sciences Antares rocket from the Mid-Atlantic Regional Spaceport (MARS) in Virginia, Sunday, April 21, 2013. The test launch marked the first flight of Antares and the first rocket launch from Pad-0A. The Antares rocket delivered the equivalent mass of a spacecraft, a so-called mass simulated payload, into Earth's orbit. Photo Credit: (NASA/Bill Ingalls)

  12. AXONOMETRIC, LAUNCH DOOR AND DOOR CYLINDER, LAUNCH PLATFORM ROLLER GUIDE, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    AXONOMETRIC, LAUNCH DOOR AND DOOR CYLINDER, LAUNCH PLATFORM ROLLER GUIDE, CRIB SUSPENSION SHOCK STRUT, LAUNCH PLATFORM - Dyess Air Force Base, Atlas F Missle Site S-8, Launch Facility, Approximately 3 miles east of Winters, 500 feet southwest of Highway 1770, center of complex, Winters, Runnels County, TX

  13. Launch of Vanguard

    NASA Technical Reports Server (NTRS)

    1955-01-01

    Launch of a three-stage Vanguard (SLV-7) from Cape Canaveral, Florida, September 18, 1959. Designated Vanguard III, the 100-pound satellite was used to study the magnetic field and radiation belt. In September 1955, the Department of Defense recommended and authorized the new program, known as Project Vanguard, to launch Vanguard booster to carry an upper atmosphere research satellite in orbit. The Vanguard vehicles were used in conjunction with later booster vehicle such as the Thor and Atlas, and the technique of gimbaled (movable) engines for directional control was adapted to other rockets.

  14. Expedition 18 Launch Day

    NASA Image and Video Library

    2008-10-11

    Expedition 18 Flight Engineer Yuri V. Lonchakov, bottom, Expedition 18 Commander Michael Fincke and American spaceflight participant Richard Garriott, top, wave farewell from the steps of the Soyuz launch pad prior to their launch in the Soyuz TMA-13 spacecraft, Sunday, Oct. 12, 2008 from the Baikonur Cosmodrome in Kazakhstan. The three crew members are scheduled to dock with the International Space Station on Oct. 14. Fincke and Lonchakov will spend six months on the station, while Garriott will return to Earth Oct. 24 with two of the Expedition 17 crew members currently on the International Space Station. Photo Credit: (NASA/Bill Ingalls)

  15. LAUNCH - APOLLO 9 - CAPE

    NASA Image and Video Library

    1969-03-03

    S69-25862 (3 March 1969) --- Framed by palm trees in the foreground, the Apollo 9 (Spacecraft 104/Lunar Module 3/ Saturn 504) space vehicle is launched from Pad A, Launch Complex 39, Kennedy Space Center (KSC) at 11 a.m. (EST), March 3, 1969. Aboard the spacecraft are astronauts James A. McDivitt, commander; David R. Scott, command module pilot; and Russell L. Schweickart, lunar module pilot. The Apollo 9 mission will evaluate spacecraft lunar module systems performance during manned Earth-orbital flight. Apollo 9 is the second manned Saturn V mission.

  16. APOLLO VII - LAUNCH - KSC

    NASA Image and Video Library

    1968-10-11

    S68-48662 (11 Oct. 1968) --- The Apollo 7/Saturn IB space vehicle is launched from the Kennedy Space Center's Launch Complex 34 at 11:03 a.m. (EDT), Oct. 11, 1968. Apollo 7 (Spacecraft 101/Saturn 205) is the first of several manned flights aimed at qualifying the spacecraft for the half-million mile round trip to the moon. Aboard the Apollo spacecraft are astronauts Walter M. Schirra Jr., commander; Donn F. Eisele, command module pilot; and Walter Cunningham, lunar module pilot. (This view is framed by palm trees on either side).

  17. NPP Satellite Launch

    NASA Image and Video Library

    2011-10-28

    The Satellite Operations Facility of the National Oceanic and Atmospheric Administration (NOAA) is seen here minutes before the launch of the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) on Friday, Oct. 28, 2011 in Suitland, Md. NPP is a joint venture between NASA and NOAA, and is the nation's newest Earth-observing satellite, which will provide data on climate change science, allow for accurate weather forecasts and advance warning for severe weather. NPP was launched from Vandenberg Air Force Base in California. Photo Credit: (NASA/Carla Cioffi)

  18. NPP Satellite Launch

    NASA Image and Video Library

    2011-10-28

    Dr. Kathy Sullivan, center, Deputy Administrator of the National Oceanic and Atmospheric Administration (NOAA) and former NASA astronaut is interviewed by a local television network at NOAA's Satellite Operations Facility in Suitland, Md. after the successful launch of the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) on Friday, Oct. 28, 2011. NPP is a joint venture between NASA and NOAA, and is the nation's newest Earth-observing satellite, which will provide data on climate change science, allow for accurate weather forecasts and advance warning for severe weather. NPP was launched from Vandenberg Air Force Base in California. Photo Credit: (NASA/Carla Cioffi)

  19. NPP Satellite Launch

    NASA Image and Video Library

    2011-10-28

    NASA Deputy Administrator Lori Garver, left, watches the launch of the National Polar-orbiting Operational Environmental Satellite System Preparatory Project (NPP) at the National Oceanic and Atmospheric Administration (NOAA) Satellite Operations Center on Friday, Oct. 28, 2011 in Suitland, Md. U.S Congresswoman Donna Edwards, D-Md., is seen next to Garver. NPP is a joint venture between NASA and NOAA, and is the nation's newest Earth-observing satellite, which will provide data on climate change science, allow for accurate weather forecasts and advance warning for severe weather. NPP was launched from Vandenberg Air Force Base in California. Photo Credit: (NASA/Carla Cioffi)

  20. Expedition 8 Launch Day

    NASA Image and Video Library

    2003-10-18

    With a throng of reporters looking on, the prime and backup crews for the Expedition 8 mission to the International Space Station and the prime and backup European Space Agency Astronauts receive final well-wishes from Russian and U.S. space officials at the Baikonur Cosmodrome in Kazakhstan, Saturday, Oct. 18, 2003, before heading to the launch pad. Expedition 8 Commander and NASA Science Officer Michael Foale, Expedition 8 Soyuz Commander Alexander Kaleri and ESA's Pedro Duque of Spain were launched on a Soyuz TMA-3 vehicle, arriving at the ISS on Oct. 20. Photo Credit (NASA/Bill Ingalls)

  1. LDSD Ready for Launch

    NASA Image and Video Library

    2015-06-05

    NASA's Low-Density Supersonic Decelerator (LDSD) hangs from a launch tower at U.S. Navy's Pacific Missile Range Facility in Kauai, Hawaii. The saucer-shaped vehicle will test two devices for landing heavy payloads on Mars: an inflatable donut-shaped device and a supersonic parachute. The launch tower helps link the vehicle to a balloon; once the balloon floats up, the vehicle is released from the tower and the balloon carries it to high altitudes. The vehicle's rocket takes it to even higher altitudes, to the top of the stratosphere, where the supersonic test begins. http://photojournal.jpl.nasa.gov/catalog/PIA19342

  2. STS-64 launch view

    NASA Technical Reports Server (NTRS)

    1994-01-01

    With a crew of six NASA astronauts aboard, the Space Shuttle Discovery heads for its nineteenth Earth-orbital mission. Launch was delayed because of weather, but all systems were 'go,' and the spacecraft left the launch pad at 6:23 p.m. (EDT) on September 9, 1994. Onboard were astronauts Richard N. Richards, L. Blaine Hammond, Carl J. Meade, Mark C. Lee, Susan J. Helms, and Jerry M. Linenger (051-2); Making a bright reflection in nearby marsh waters, the Space Shuttle Discovery heads for its 19th mission in earth orbit (053).

  3. STS-64 launch view

    NASA Technical Reports Server (NTRS)

    1994-01-01

    With a crew of six NASA astronauts aboard, the Space Shuttle Discovery heads for its nineteenth Earth-orbital mission. Launch was delayed because of weather, but all systems were 'go,' and the spacecraft left the launch pad at 6:23 p.m. (EDT) on September 9, 1994. Onboard were astronauts Richard N. Richards, L. Blaine Hammond, Carl J. Meade, Mark C. Lee, Susan J. Helms, and Jerry M. Linenger (051-2); Making a bright reflection in nearby marsh waters, the Space Shuttle Discovery heads for its 19th mission in earth orbit (053).

  4. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 Flight Engineer Soichi Noguchi of Japan has his Russian Sokol suit prepared for launch by a technician while space agency photographers document the process at the Baikonur Cosmodrome in Baikonur, Kazakhstan, Sunday, Dec. 20, 2009. Soichi and fellow Expedition 22 crew members NASA Flight Engineer Timothy J. Creamer of the U.S., Soyuz Commander Oleg Kotov of Russia launched in their Soyuz TMA-17 rocket from the Baikonur Cosmodrome in Kazakhstan on Monday, Dec. 21, 2009. (Photo Credit: NASA/Bill Ingalls)

  5. Launch - STS-6 - KSC

    NASA Image and Video Library

    1983-04-06

    S83-30134 (7 April 1983) --- Flare from the first launch of the space shuttle Challenger is reflected in the Atlantic Ocean?s Cape Canaveral beach waters shortly after 1:30 p.m. (EST) on April 7, 1983. Only the tips of the orbiter?s wings are visible in this south looking view, as the manned portion of the launch cluster is obscured by its new lightweight external fuel tank (ET) and two solid rocket boosters (SRB). Onboard the spacecraft are astronauts Paul J. Weitz, Karol J. Bobko, Dr. F. Story Musgrave and Donald H. Peterson. Photo credit: NASA

  6. STS-56 Launch

    NASA Technical Reports Server (NTRS)

    1993-01-01

    The second try works like a charm as the Space Shuttle Discovery lifts off from Launch Pad 39B on Mission STS-56 at 1:29:00 a.m., EDT, April 8. First attempt to launch Discovery on its 16th space voyage was halted at T-11 seconds on April 6. Aboard for the second Space Shuttle mission of 1993 are a crew of five and the Atmospheric Laboratory for Applications and Science 2 (ATLAS 2), the second in a series of missions to study the sun's energy output and Earth's middle atmosphere chemical makeup, and how these factors affect levels of ozone.

  7. Mars Acoustic Anemometer

    NASA Astrophysics Data System (ADS)

    Banfield, D.; Gierasch, P. J.; Toigo, A.; Dissly, R.; Dagle, W. R.; Schindel, D.; Hutchins, D.; Khuri-Yakub, B. T.

    2004-05-01

    We are developing an acoustic anemometer for use in the low pressure atmosphere of Mars. Acoustic anemometers have high sensitivity, high temporal resolution, high accuracy, and are insensitive to radiative heating and demand little power. In these ways they are superior to the anemometers previously flown to Mars. Accurate, well-calibrated anemometers are crucial for understanding the near-surface atmospheric environment (e.g., slope winds, convective cells, dust devils, and aeolian processes in general). Furthermore, the high time-resolution, sensitivity, 3-D capabilities and well-defined, open sampling volume available from an acoustic anemometer allow it to resolve individual turbulent eddies, a first for Mars. This feature allows it to directly measure eddy fluxes, for example water vapor vertical fluxes between the surface and atmosphere when coupled with a fast hygrometer (e.g. a TDL). This novel ability to measure water vapor fluxes is viewed as a high priority science goal of Mars landers. We expect that the instrument designed in this program will be a prime candidate to fly on either the Mars Science Laboratory Lander (2009 launch), or any of the future planned Mars Scout landers or Mars Surveyor Landers. With adaptation, the instrument could also find application on Titan, or at high altitude on Earth. Acoustic anemometers are well developed for Earth, but need modifications to function in the vastly different martian pressure environment. The two main hurdles are sound attenuation in Mars air, and transducer coupling inefficiency from density and sound speed mismatches with Mars air. The sound attenuation on Mars is significant, especially at ultrasonic frequencies. We have a simple model of the relevant phenomena to guide our choices to the optimal frequencies for Mars. The coupling between a transducer and the atmosphere is characterized by the match of their densities and sound speeds, or acoustic impedances, similar to index of refraction in optics

  8. Scale Model Thruster Acoustic Measurement Results

    NASA Technical Reports Server (NTRS)

    Vargas, Magda; Kenny, R. Jeremy

    2013-01-01

    The Space Launch System (SLS) Scale Model Acoustic Test (SMAT) is a 5% scale representation of the SLS vehicle, mobile launcher, tower, and launch pad trench. The SLS launch propulsion system will be comprised of the Rocket Assisted Take-Off (RATO) motors representing the solid boosters and 4 Gas Hydrogen (GH2) thrusters representing the core engines. The GH2 thrusters were tested in a horizontal configuration in order to characterize their performance. In Phase 1, a single thruster was fired to determine the engine performance parameters necessary for scaling a single engine. A cluster configuration, consisting of the 4 thrusters, was tested in Phase 2 to integrate the system and determine their combined performance. Acoustic and overpressure data was collected during both test phases in order to characterize the system's acoustic performance. The results from the single thruster and 4- thuster system are discussed and compared.

  9. Evolution of ion-acoustic plasma turbulence

    NASA Astrophysics Data System (ADS)

    Bychenkov, V. Iu.; Gradov, O. M.

    1986-03-01

    The evolution of ion-acoustic turbulence is studied on the basis of a numerical solution of the nonstationary equation for in-acoustic waves. Consideration is given to conditions under which the excitation threshold of long-wave ion-acoustic oscillations is exceeded as the result of instability saturation due to quasi-linear relaxation of electrons on turbulent pulsations and the induced scattering of ions by the ion sound. Distributed spectra of ion-acoustic turbulence are established in the plasma under these conditions.

  10. Musical Acoustics

    NASA Astrophysics Data System (ADS)

    Gough, Colin

    This chapter provides an introduction to the physical and psycho-acoustic principles underlying the production and perception of the sounds of musical instruments. The first section introduces generic aspects of musical acoustics and the perception of musical sounds, followed by separate sections on string, wind and percussion instruments.

  11. NASA Launch Services Program Overview

    NASA Technical Reports Server (NTRS)

    Higginbotham, Scott

    2016-01-01

    The National Aeronautics and Space Administration (NASA) has need to procure a variety of launch vehicles and services for its unmanned spacecraft. The Launch Services Program (LSP) provides the Agency with a single focus for the acquisition and management of Expendable Launch Vehicle (ELV) launch services. This presentation will provide an overview of the LSP and its organization, approach, and activities.

  12. Voyager 1's Launch Vehicle

    NASA Image and Video Library

    1977-09-05

    The Titan/Centaur-6 launch vehicle was moved to Launch Complex 41 at Kennedy Space Center in Florida to complete checkout procedures in preparation for launch. The photo is dated January 1977. This launch vehicle carried Voyager 1 into space on September 5, 1977. https://photojournal.jpl.nasa.gov/catalog/PIA21739

  13. Acoustic Characterization of Mesoscale Objects

    SciTech Connect

    Chinn, D; Huber, R; Chambers, D; Cole, G; Balogun, O; Spicer, J; Murray, T

    2007-03-13

    This report describes the science and engineering performed to provide state-of-the-art acoustic capabilities for nondestructively characterizing mesoscale (millimeter-sized) objects--allowing micrometer resolution over the objects entire volume. Materials and structures used in mesoscale objects necessitate the use of (1) GHz acoustic frequencies and (2) non-contacting laser generation and detection of acoustic waves. This effort demonstrated that acoustic methods at gigahertz frequencies have the necessary penetration depth and spatial resolution to effectively detect density discontinuities, gaps, and delaminations. A prototype laser-based ultrasonic system was designed and built. The system uses a micro-chip laser for excitation of broadband ultrasonic waves with frequency components reaching 1.0 GHz, and a path-stabilized Michelson interferometer for detection. The proof-of-concept for mesoscale characterization is demonstrated by imaging a micro-fabricated etched pattern in a 70 {micro}m thick silicon wafer.

  14. SPIDER Readied for Launch

    NASA Image and Video Library

    2015-01-22

    Prior to launch, the team laid out the parachute and hang lines in front of SPIDER, seen in the distance. The long-duration balloon that would carry SPIDER into the sky is attached to the end of the parachute shown here in the foreground. http://photojournal.jpl.nasa.gov/catalog/PIA19177

  15. NanoLaunch

    NASA Technical Reports Server (NTRS)

    Jones, Jonathan; Harris, Lawanna

    2015-01-01

    NASA's NanoLaunch effort will provide the framework to mature both Earth-to-orbit and on-orbit propulsion and avionics technologies while also providing affordable, dedicated access to low-Earth orbit for CubeSat-class payloads. The project will also serve as an early career personnel training opportunity with mentors to gain hands-on project experience.

  16. Expedition 23 Launch Day

    NASA Image and Video Library

    2010-04-01

    Expedition 23 Flight Engineer Tracy Caldwell Dyson performs the traditional door signing Friday, April 2, 2010 at the Cosmonaut Hotel in Baikonur, Kazakhstan. Caldwell Dyson was launched onboard the Soyuz rocket later that day with Expedition 23 Soyuz Commander Alexander Skvortsov and Flight Engineer Mikhail Kornienko on a mission to the International Space Station (ISS). Photo Credit: (NASA/Carla Cioffi)

  17. STS-120 launch

    NASA Image and Video Library

    2007-10-23

    STS120-S-025 (23 Oct. 2007) --- In the firing room at NASA's Kennedy Space Center, NASA Associate Administrator Chris Scolese and other managers watch the Space Shuttle Discovery launch of the STS-120 mission at 11:38 a.m. (EDT), Oct. 23, 2007. William Gerstenmaier is in right foreground. Photo credit: NASA/Bill Ingalls

  18. Expedition 8 Launch Briefing

    NASA Image and Video Library

    2003-10-12

    Backup Expedition 8 Commander Bill McArthur, left, and prime Expedition 8 Commander Michael Foale practice procedures with a satellite phone during final training at their crew quarters in Baikonur, Kazakhstan, Wednesday, Oct. 15, 2003, for launch on a Soyuz TMA-3 vehicle Oct. 18 to the International Space Station. Photo Credit (NASA/Bill Ingalls)

  19. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 NASA Flight Engineer Scott Kelly of the U.S., left, Soyuz Commander Alexander Kaleri and Flight Engineer Oleg Skripochka, right, have their Russian Sokol suits prepared for launch by technicians at the Baikonur Cosmodrome in Kazakhstan, Friday, Oct. 8, 2010. (Photo Credit: NASA/Carla Cioffi)

  20. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 crew members prepare to have their Russian Sokol Suits pressure checked at the Baikonur Cosmodrome in Kazakhstan on Friday, Oct. 8, 2010. Soyuz Commander Alexander Kaleri, NASA Flight Engineer Scott Kelly and Flight Engineer Oleg Skripochka launched in their Soyuz TMA-01M at 5:10 a.m. Friday morning. (Photo Credit: NASA/Carla Cioffi)

  1. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 Soyuz Commander Alexander Kaleri awaits to have his Russian Sokol Suit pressure checked at the Baikonur Cosmodrome on Friday, Oct. 8, 2010 in Kazakhstan. Kaleri and fellow Expedition 25 crew members Flight Engineers Scott Kelly and Oleg Skripochka launched in their Soyuz TMA-01M at 5:10 a.m. Friday morning. (Photo Credit: NASA/Carla Cioffi)

  2. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 Soyuz Commander Alexander Kaleri awaits to have his Russian Sokol Suit pressure checked at the Baikonur Cosmodrome on Friday, Oct. 8, 2010 in Baikonur, Kazakhstan. Kaleri and fellow Expedition 25 crew members Flight Engineers Scott Kelly and Oleg Skripochka launched in their Soyuz TMA-01M at 5:10 a.m. Friday morning. (Photo Credit: NASA/Carla Cioffi)

  3. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 NASA Flight Engineer Scott Kelly of the U.S., left, and Soyuz Commander Alexander Kaleri have their Russian Sokol suits prepared for launch by technicians at the Baikonur Cosmodrome in Kazakhstan, Friday, Oct. 8, 2010. (Photo Credit: NASA/Carla Cioffi)

  4. Expedition 25 Launch

    NASA Image and Video Library

    2010-10-07

    Expedition 25 Flight Engineer Oleg Skripochka awaits to have his Russian Sokol Suit pressure checked at the Baikonur Cosmodrome on Friday, Oct. 8, 2010 in Kazakhstan. Skripochka, Soyuz Commander Alexander Kaleri and NASA Flight Engineer Scott Kelly launched in their Soyuz TMA-01M at 5:10 a.m. Friday morning. (Photo Credit: NASA/Carla Cioffi)

  5. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 Soyuz Commander Oleg Kotov of Russia smiles for photographers after performing the traditional door signing at the Cosmonaut Hotel in Baikonur, Kazakhstan before departing with fellow crew members, NASA Flight Engineer Timothy J. Creamer of the U.S., and Flight Engineer Soichi Noguchi of Japan to suit up for their launch, Sunday, Dec. 20, 2009. Photo Credit: (NASA/Bill Ingalls)

  6. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 Flight Engineer Soichi Noguchi of Japan smiles for photographers after performing the traditional door signing at the Cosmonaut Hotel in Baikonur, Kazakhstan before departing with fellow crew members, Soyuz Commander Oleg Kotov of Russia, and NASA Flight Engineer Timothy J. Creamer of the U.S. to suit up for their launch, Sunday, Dec. 20, 2009. Photo Credit: (NASA/Bill Ingalls)

  7. Expedition 22 Launch Day

    NASA Image and Video Library

    2009-12-20

    Expedition 22 NASA Flight Engineer Timothy J. Creamer of the U.S. smiles for photographers after performing the traditional door signing at the Cosmonaut Hotel in Baikonur, Kazakhstan before departing with fellow crew members, Soyuz Commander Oleg Kotov of Russia, and Flight Engineer Soichi Noguchi of Japan to suit up for their launch, Sunday, Dec. 20, 2009. Photo Credit: (NASA/Bill Ingalls)

  8. The Personnel Launch System

    NASA Technical Reports Server (NTRS)

    Piland, William M.; Talay, Theodore A.; Stone, Howard W.

    1990-01-01

    NASA has begun to study candidate vehicles for manned access to space in support of the Space Station or other future missions requiring on-demand transportation of people to and from earth orbit. One such system, which would be used to complement the present Shuttle or an upgraded version, is the Personnel Launch System (PLS), which is envisioned as a reusable priority vehicle to place people and small payloads into orbit using an experimental launch vehicle. The design of the PLS is based on a Space Station crew changeout requirement whereby eight passengers and two crew members are flown to the station and a like number are returned within a 72 hour mission duration. Experimental and computational aerothermodynamic heating studies have been conducted using a new two-color thermographic technique that involved coating the model with a phosphor that radiates at varying color intensities as a function of temperature when illuminated with UV light. A full-scale model, the HL-20, has been produced and will be used for man-machine research. Three launch vehicle concepts are being considered, a Titan IV, the Advanced Launch System, and a Shuttle equipped with liquid rocket boosters.

  9. Expedition 8 Launch Day

    NASA Image and Video Library

    2003-10-18

    Expedition 8 Commander and NASA Science Officer Michael Foale smiles for the camera during the short bus ride to the launch pad for liftoff in a Soyuz TMA-3 vehicle to the International Space Station, Saturday, Oct. 18, 2003, at the Baikonur Cosmodrome, Kazakhstan. Photo Credit (NASA/Bill Ingalls)

  10. Expedition 8 Launch Briefing

    NASA Image and Video Library

    2003-10-12

    European Space Agency astronaut Pedro Duque of Spain listens to a briefing on mission activities from a Russian trainer at his crew quarters in Baikonur, Kazakhstan, Wednesday, Oct. 15, 2003 as he prepares for his launch to the International Space Station Oct. 18 in a Soyuz TMA-3 vehicle. Photo Credit (NASA/Bill Ingalls)

  11. Chirp excitation

    NASA Astrophysics Data System (ADS)

    Khaneja, Navin

    2017-09-01

    The paper describes the design of broadband chirp excitation pulses. We first develop a three stage model for understanding chirp excitation in NMR. We then show how a chirp π pulse can be used to refocus the phase of the chirp excitation pulse. The resulting magnetization still has some phase dispersion in it. We show how a combination of two chirp π pulses instead of one can be used to eliminate this dispersion, leaving behind a small residual phase dispersion. The excitation pulse sequence presented here allows exciting arbitrary large bandwidths without increasing the peak rf-amplitude. Experimental excitation profiles for the residual HDO signal in a sample of 99.5 % D2O are displayed as a function of resonance offset. Although methods presented in this paper have appeared elsewhere, we present complete analytical treatment that elucidates the working of these methods.

  12. Acoustical oceanography

    NASA Astrophysics Data System (ADS)

    The Acoustical Society of America has formed a Technical Specialty Group on Acoustical Oceanography. At ASA meetings the new group will have special sessions where they will give invited and contributed papers and have panel discussions about ocean parameters that are measured effectively by acoustical techniques.The first special sessions will be May 22-23, 1990, at the ASA meeting at Pennsylvania State University, University Park. The focus on May 22 will be acoustical techniques for detection and measurement of internal waves and turbulence; conveners are Robert Pinkel of Scripps Institution of Oceanography, La Jolla, Calif., and Herman Medwin of the Naval Postgraduate School, Monterey, Calif. Acoustical studies of the physical and biological characteristics of ocean mass boundaries are the discussion topic on May 23. The convener is C. S. Clay, University of Wisconsin, Madison.

  13. Successful launch of SOHO

    NASA Astrophysics Data System (ADS)

    1995-12-01

    "Understanding how the Sun behaves is of crucial importance to all of us on Earth. It affects our everyday lives" said Roger Bonnet, Director of Science at ESA, who witnessed SOHO's spectacular nighttime launch from Cape Canaveral. "When SOHO begins work in four months time, scientists will, for the first time, be able to study this star 24 hours a day, 365 days a year". The 12 instruments on SOHO will probe the Sun inside out, from the star's very centre to the solar wind that blasts its way through the solar system. It will even listen to sounds, like musical notes, deep within the star by recording their vibrations when they reach the surface. SOHO was launched from Cape Canaveral Air Station, Florida, atop an Atlas IIAS rocket, at 09:08 CET on Saturday 2 December 1995. The 1.6 tonne observatory was released into its transfer orbit from the rocket's Centaur upper stage about two hours after launch. It will take four months for the satellite to reach its final position, a unique vantage point, located 1.5 million kilometres from Earth, where the gravitational pull of the Earth and Sun are equal. From here, the Lagrange point, SOHO will have an unobstructed view of the Sun all year round. SOHO's launch was delayed from 23 November because a flaw was discovered in a precision regulator, which throttles the power of the booster engine on the Atlas rocket. The system was replaced and retested before the launch. SOHO is a project of international cooperation between ESA and NASA. The spacecraft was designed and built in Europe, NASA provided the launch and will operate the satellite from its Goddard Space Flight Center, Maryland. European scientists provided eight of the observatory's instruments and US scientists a further three. The spacecraft is part of the international Solar-Terrestrial Science Programme, the next member of which is Cluster, a flotilla of four spacecraft that will study how the Sun affects Earth and surrounding space. Cluster is scheduled for

  14. Exciter switch

    NASA Technical Reports Server (NTRS)

    Mcpeak, W. L.

    1975-01-01

    A new exciter switch assembly has been installed at the three DSN 64-m deep space stations. This assembly provides for switching Block III and Block IV exciters to either the high-power or 20-kW transmitters in either dual-carrier or single-carrier mode. In the dual-carrier mode, it provides for balancing the two drive signals from a single control panel located in the transmitter local control and remote control consoles. In addition to the improved switching capabilities, extensive monitoring of both the exciter switch assembly and Transmitter Subsystem is provided by the exciter switch monitor and display assemblies.

  15. Simulation of Acoustics for Ares I Scale Model Acoustic Tests

    NASA Technical Reports Server (NTRS)

    Putnam, Gabriel; Strutzenberg, Louise L.

    2011-01-01

    The Ares I Scale Model Acoustics Test (ASMAT) is a series of live-fire tests of scaled rocket motors meant to simulate the conditions of the Ares I launch configuration. These tests have provided a well documented set of high fidelity acoustic measurements useful for validation including data taken over a range of test conditions and containing phenomena like Ignition Over-Pressure and water suppression of acoustics. To take advantage of this data, a digital representation of the ASMAT test setup has been constructed and test firings of the motor have been simulated using the Loci/CHEM computational fluid dynamics software. Results from ASMAT simulations with the rocket in both held down and elevated configurations, as well as with and without water suppression have been compared to acoustic data collected from similar live-fire tests. Results of acoustic comparisons have shown good correlation with the amplitude and temporal shape of pressure features and reasonable spectral accuracy up to approximately 1000 Hz. Major plume and acoustic features have been well captured including the plume shock structure, the igniter pulse transient, and the ignition overpressure.

  16. NLS Advanced Development - Launch operations

    NASA Technical Reports Server (NTRS)

    Parrish, Carrie L.

    1992-01-01

    Attention is given to Autonomous Launch Operations (ALO), one of a number of the USAF's National Launch System (NLS) Launch Operations projects whose aim is to research, develop and apply new technologies and more efficient approaches toward launch operations. The goal of the ALO project is to develop generic control and monitor software for launch operation subsystems. The result is enhanced reliability of system design, and reduced software development and retention of expert knowledge throughout the life-cycle of the system.

  17. Contracting and launching small satellites with the Rockot launch vehicle

    NASA Astrophysics Data System (ADS)

    Kinnersley, M.; Zorina, A.; Leclerc, J.

    2004-11-01

    Arranging secondary payload 'rides' with launch vehicles can be a lengthy and often frustrating process, especially with a shared or cluster launch with a multitude of customers that need to be coordinated. Eurockot's point of view on what can be done to improve this process is given. The objective is to initiate discussions within the community on how to improve access to launch services whilst mutually benefiting both the provider and end user. Eurockot is one of the most active launch service companies in the world for providing small satellite launch services. In 2003, Eurockot placed nine payloads into three different orbits during one launch, including the first Cubesats to be orbited. In particular the results of the most recent launches will be reported. The flexibility and capabilities of the Rockot launch vehicle for launching small satellites especially in the secondary or shared payloads sector will also be shown.

  18. Acoustic Test Results of Melamine Foam with Application to Payload Fairing Acoustic Attenuation Systems

    NASA Technical Reports Server (NTRS)

    Hughes, William O.; McNelis, Anne M.

    2014-01-01

    A spacecraft at launch is subjected to a harsh acoustic and vibration environment resulting from the passage of acoustic energy, created during the liftoff of a launch vehicle, through the vehicle's payload fairing. In order to ensure the mission success of the spacecraft it is often necessary to reduce the resulting internal acoustic sound pressure levels through the usage of acoustic attenuation systems. Melamine foam, lining the interior walls of the payload fairing, is often utilized as the main component of such a system. In order to better understand the acoustic properties of melamine foam, with the goal of developing improved acoustic attenuation systems, NASA has recently performed panel level testing on numerous configurations of melamine foam acoustic treatments at the Riverbank Acoustical Laboratory. Parameters assessed included the foam's thickness and density, as well as the effects of a top outer cover sheet material and mass barriers embedded within the foam. This testing followed the ASTM C423 standard for absorption and the ASTM E90 standard for transmission loss. The acoustic test data obtained and subsequent conclusions are the subjects of this paper.

  19. Cassini launch contingency effort

    NASA Astrophysics Data System (ADS)

    Chang, Yale; O'Neil, John M.; McGrath, Brian E.; Heyler, Gene A.; Brenza, Pete T.

    2002-01-01

    On 15 October 1997 at 4:43 AM EDT, the Cassini spacecraft was successfully launched on a Titan IVB/Centaur on a mission to explore the Saturnian system. It carried three Radioisotope Thermoelectric Generators (RTGs) and 117 Light Weight Radioisotope Heater Units (LWRHUs). As part of the joint National Aeronautics and Space Administration (NASA)/U.S. Department of Energy (DoE) safety effort, a contingency plan was prepared to address the unlikely events of an accidental suborbital reentry or out-of-orbital reentry. The objective of the plan was to develop procedures to predict, within hours, the Earth impact footprints (EIFs) for the nuclear heat sources released during the atmospheric reentry. The footprint predictions would be used in subsequent notification and recovery efforts. As part of a multi-agency team, The Johns Hopkins University Applied Physics Laboratory (JHU/APL) had the responsibility to predict the EIFs of the heat sources after a reentry, given the heat sources' release conditions from the main spacecraft. (No ablation burn-through of the heat sources' aeroshells was expected, as a result of earlier testing.) JHU/APL's other role was to predict the time of reentry from a potential orbital decay. The tools used were a three degree-of-freedom trajectory code, a database of aerodynamic coefficients for the heat sources, secure links to obtain tracking data, and a high fidelity special perturbation orbit integrator code to predict time of spacecraft reentry from orbital decay. In the weeks and days prior to launch, all the codes and procedures were exercised. Notional EIFs were derived from hypothetical reentry conditions. EIFs predicted by JHU/APL were compared to those by JPL and US SPACECOM, and were found to be in good agreement. The reentry time from orbital decay for a booster rocket for the Russian Progress M-36 freighter, a cargo ship for the Mir space station, was predicted to within 5 minutes more than two hours before reentry. For the

  20. Acoustics Research of Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Gao, Ximing; Houston, Janice

    2014-01-01

    The liftoff phase induces high acoustic loading over a broad frequency range for a launch vehicle. These external acoustic environments are used in the prediction of the internal vibration responses of the vehicle and components. Present liftoff vehicle acoustic environment prediction methods utilize stationary data from previously conducted hold-down tests to generate 1/3 octave band Sound Pressure Level (SPL) spectra. In an effort to update the accuracy and quality of liftoff acoustic loading predictions, non-stationary flight data from the Ares I-X were processed in PC-Signal in two flight phases: simulated hold-down and liftoff. In conjunction, the Prediction of Acoustic Vehicle Environments (PAVE) program was developed in MATLAB to allow for efficient predictions of sound pressure levels (SPLs) as a function of station number along the vehicle using semi-empirical methods. This consisted of generating the Dimensionless Spectrum Function (DSF) and Dimensionless Source Location (DSL) curves from the Ares I-X flight data. These are then used in the MATLAB program to generate the 1/3 octave band SPL spectra. Concluding results show major differences in SPLs between the hold-down test data and the processed Ares I-X flight data making the Ares I-X flight data more practical for future vehicle acoustic environment predictions.

  1. Solid Rocket Motor Acoustic Testing

    SciTech Connect

    Rogers, J.D.

    1999-03-31

    Acoustic data are often required for the determination of launch and powered flight loads for rocket systems and payloads. Such data are usually acquired during test firings of the solid rocket motors. In the current work, these data were obtained for two tests at a remote test facility where we were visitors. This paper describes the data acquisition and the requirements for working at a remote site, interfacing with the test hosts.

  2. Air-coupled seismic waves at long range from Apollo launchings.

    NASA Technical Reports Server (NTRS)

    Donn, W. L.; Dalins, I.; Mccarty, V.; Ewing, M.; Kaschak , G.

    1971-01-01

    Microphones and seismographs were co-located in arrays on Skidaway Island, Georgia, for the launchings of Apollo 13 and 14, 374 km to the south. Simultaneous acoustic and seismic waves were recorded for both events at times appropriate to the arrival of the acoustic waves from the source. The acoustic signal is relatively broadband compared to the nearly monochromatic seismic signal; the seismic signal is much more continuous than the more pulse-like acoustic signal; ground loading from the pressure variations of the acoustic waves is shown to be too small to account for the seismic waves; and the measured phase velocities of both acoustic and seismic waves across the local instrument arrays differ by less than 6 per cent and possibly 3 per cent if experimental error is included. It is concluded that the seismic waves are generated by resonant coupling to the acoustic waves along some 10 km of path on Skidaway Island.

  3. Air-coupled seismic waves at long range from Apollo launchings.

    NASA Technical Reports Server (NTRS)

    Donn, W. L.; Dalins, I.; Mccarty, V.; Ewing, M.; Kaschak , G.

    1971-01-01

    Microphones and seismographs were co-located in arrays on Skidaway Island, Georgia, for the launchings of Apollo 13 and 14, 374 km to the south. Simultaneous acoustic and seismic waves were recorded for both events at times appropriate to the arrival of the acoustic waves from the source. The acoustic signal is relatively broadband compared to the nearly monochromatic seismic signal; the seismic signal is much more continuous than the more pulse-like acoustic signal; ground loading from the pressure variations of the acoustic waves is shown to be too small to account for the seismic waves; and the measured phase velocities of both acoustic and seismic waves across the local instrument arrays differ by less than 6 per cent and possibly 3 per cent if experimental error is included. It is concluded that the seismic waves are generated by resonant coupling to the acoustic waves along some 10 km of path on Skidaway Island.

  4. Numerical Estimation of Sound Transmission Loss in Launch Vehicle Payload Fairing

    NASA Astrophysics Data System (ADS)

    Chandana, Pawan Kumar; Tiwari, Shashi Bhushan; Vukkadala, Kishore Nath

    2017-08-01

    Coupled acoustic-structural analysis of a typical launch vehicle composite payload faring is carried out, and results are validated with experimental data. Depending on the frequency range of interest, prediction of vibro-acoustic behavior of a structure is usually done using the finite element method, boundary element method or through statistical energy analysis. The present study focuses on low frequency dynamic behavior of a composite payload fairing structure using both coupled and uncoupled vibro-acoustic finite element models up to 710 Hz. A vibro-acoustic model, characterizing the interaction between the fairing structure, air cavity, and satellite, is developed. The external sound pressure levels specified for the payload fairing's acoustic test are considered as external loads for the analysis. Analysis methodology is validated by comparing the interior noise levels with those obtained from full scale Acoustic tests conducted in a reverberation chamber. The present approach has application in the design and optimization of acoustic control mechanisms at lower frequencies.

  5. Electromagnetic Cavity Effects from Transmitters Inside a Launch Vehicle Fairing

    NASA Technical Reports Server (NTRS)

    Trout, Dawn H.; Wahid, Parveen F.; Stanley, James E.

    2009-01-01

    This paper provides insight into the difficult analytical issue for launch vehicles and spacecraft that has applicability outside of the launch industry. Radiation from spacecraft or launch vehicle antennas located within enclosures in the launch vehicle generates an electromagnetic environment that is difficult to accurately predict. This paper discusses the test results of power levels produced by a transmitter within a representative scaled vehicle fairing model and provides preliminary modeling results at the low end of the frequency test range using a commercial tool. Initially, the walls of the fairing are aluminum and later, layered with materials to simulate acoustic blanketing structures that are typical in payload fairings. The effects of these blanketing materials on the power levels within the fairing are examined.

  6. A perfect launch

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Billows of smoke and steam spread across Launch Pad 39A as Space Shuttle Discovery lifts off on mission STS-92 to the International Space Station. The perfect on-time liftoff occurred at 7:17 p.m. EDT, sending a crew of seven on the 100th launch in the history of the Shuttle program. Discovery carries a payload that includes the Integrated Truss Structure Z-1, first of 10 trusses that will form the backbone of the Space Station, and the third Pressurized Mating Adapter that will provide a Shuttle docking port for solar array installation on the sixth Station flight and Lab installation on the seventh Station flight. Discovery's landing is expected Oct. 22 at 2:10 p.m. EDT.

  7. STS-133 launch

    NASA Image and Video Library

    2011-02-24

    STS133-S-066 (24 Feb. 2011) --- In Firing Room 4 of the Launch Control Center at NASA's Kennedy Space Center in Florida, Shuttle Launch Director Mike Leinbach watches space shuttle Discovery head toward Earth orbit on the STS-133 mission to the International Space Station. Discovery and its six-member crew are on a mission to deliver the Permanent Multipurpose Module, packed with supplies and critical spare parts, as well as Robonaut 2, the dexterous humanoid astronaut helper, to the orbiting outpost. Discovery is making its 39th mission and is scheduled to be retired following STS-133. This is the 133rd Space Shuttle Program mission and the 35th shuttle voyage to the space station. Photo credit: NASA or National Aeronautics and Space Administration

  8. LAUNCH - STS-7 - KSC

    NASA Image and Video Library

    1983-06-18

    S83-35620 (18 June 1983) --- The space shuttle Challenger, its two solid rocket boosters and an external fuel tank carry the five-member STS-7 astronaut crew toward a six-day mission in Earth orbit. This high-angle view of the liftoff, a lengthy stretch of Florida Atlantic coastline and a number of large cumulus clouds was photographed with a handheld 70mm camera by astronaut John W. Young. Young usually pilots the Shuttle Training Aircraft (STA) for weather monitoring at launch and landing sites for STS missions. The Challenger?s second launch occurred at 7:33 a.m. (EDT) on 18 June 1983. Photo credit: NASA

  9. STS-121 Launch

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Space Shuttle Discovery and its seven-member crew launched at 2:38 p.m. (EDT) to begin the two-day journey to the International Space Station (ISS) on the historic Return to Flight STS-121 mission. The shuttle made history as it was the first human-occupying spacecraft to launch on Independence Day. During its 12-day mission, this utilization and logistics flight delivered a multipurpose logistics module (MPLM) to the ISS with several thousand pounds of new supplies and experiments. In addition, some new orbital replacement units (ORUs) were delivered and stowed externally on the ISS on a special pallet. These ORUs are spares for critical machinery located on the outside of the ISS. During this mission the crew also carried out testing of Shuttle inspection and repair hardware, as well as evaluated operational techniques and concepts for conducting on-orbit inspection and repair.

  10. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-021 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  11. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-009 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  12. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-008 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  13. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-011 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  14. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-016 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  15. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-014 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  16. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-018 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  17. STS-116 Launch

    NASA Image and Video Library

    2006-12-09

    STS116-S-010 (9 Dec. 2006) --- Against a black night sky, the Space Shuttle Discovery and its seven-member crew head toward Earth-orbit and a scheduled link-up with the International Space Station. Liftoff from the Kennedy Space Center's launch pad 39B occurred at 8:47 p.m. (EST) on Dec. 9, 2006 in what was the first evening shuttle launch since 2002. The STS-116 crew will link up with the station on Monday, Dec. 11, to begin a complex, week-long stay that will rewire the outpost and increase its power supply. During three spacewalks and intricate choreography with ground controllers, the astronauts will bring electrical power on line generated by a giant solar array wing delivered to the station in September.

  18. Computational simulation of acoustic fatigue for hot composite structures

    NASA Technical Reports Server (NTRS)

    Singhal, Surendra N.; Murthy, Pappu L. N.; Chamis, Christos C.; Nagpal, Vinod K.; Sutjahjo, Edhi

    1991-01-01

    Predictive methods/computer codes for the computational simulation of acoustic fatigue resistance of hot composite structures subjected to acoustic excitation emanating from an adjacent vibrating component are discussed. Select codes developed over the past two decades at the NASA Lewis Research Center are used. The codes include computation of acoustic noise generated from a vibrating component, degradation in material properties of a composite laminate at use temperature, dynamic response of acoustically excited hot multilayered composite structure, degradation in the first ply strength of the excited structure due to acoustic loading, and acoustic fatigue resistance of the excited structure, including the propulsion environment. Effects of the laminate lay-up and environment on the acoustic fatigue life are evaluated. The results show that, by keeping the angled plies on the outer surface of the laminate, a substantial increase in the acoustic fatigue life is obtained. The effect of environment (temperature and moisture) is to relieve the residual stresses leading to an increase in the acoustic fatigue life of the excited panel.

  19. Detecting Structural Failures Via Acoustic Impulse Responses

    NASA Technical Reports Server (NTRS)

    Bayard, David S.; Joshi, Sanjay S.

    1995-01-01

    Advanced method of acoustic pulse reflectivity testing developed for use in determining sizes and locations of failures within structures. Used to detect breaks in electrical transmission lines, detect faults in optical fibers, and determine mechanical properties of materials. In method, structure vibrationally excited with acoustic pulse (a "ping") at one location and acoustic response measured at same or different location. Measured acoustic response digitized, then processed by finite-impulse-response (FIR) filtering algorithm unique to method and based on acoustic-wave-propagation and -reflection properties of structure. Offers several advantages: does not require training, does not require prior knowledge of mathematical model of acoustic response of structure, enables detection and localization of multiple failures, and yields data on extent of damage at each location.

  20. Expedition 11 Launch Day

    NASA Image and Video Library

    2005-04-15

    Unidentified family members of NASA astronaut John Phillips waves offers up best wishes for a safe mission and a happy birthday prior to launch, Friday, April 15, 2005, aboard the Soyuz TMA-6 spacecraft from the Baikonur Cosmodrome in Kazakhstan for a two-day trip to the International Space Station where he will spend six months living in space. Photo Credit: (NASA/Bill Ingalls)