thrust stand motion: Topics by Science.gov

Sample records for thrust stand motion

Non-contact thrust stand calibration method for repetitively pulsed electric thrusters.

PubMed

Wong, Andrea R; Toftul, Alexandra; Polzin, Kurt A; Pearson, J Boise

2012-02-01

A thrust stand calibration technique for use in testing repetitively pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoid to produce a pulsed magnetic field that acts against a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasi-steady average deflection of the thrust stand arm away from the unforced or "zero" position can be related to the average applied force through a simple linear Hooke's law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other. The overall error on the linear regression fit used to determine the calibration coefficient was roughly 1%.
Non-Contact Thrust Stand Calibration Method for Repetitively-Pulsed Electric Thrusters

NASA Technical Reports Server (NTRS)

Wong, Andrea R.; Toftul, Alexandra; Polzin, Kurt A.; Pearson, J. Boise

2011-01-01

A thrust stand calibration technique for use in testing repetitively-pulsed electric thrusters for in-space propulsion has been developed and tested using a modified hanging pendulum thrust stand. In the implementation of this technique, current pulses are applied to a solenoidal coil to produce a pulsed magnetic field that acts against the magnetic field produced by a permanent magnet mounted to the thrust stand pendulum arm. The force on the magnet is applied in this non-contact manner, with the entire pulsed force transferred to the pendulum arm through a piezoelectric force transducer to provide a time-accurate force measurement. Modeling of the pendulum arm dynamics reveals that after an initial transient in thrust stand motion the quasisteady average deflection of the thrust stand arm away from the unforced or zero position can be related to the average applied force through a simple linear Hooke s law relationship. Modeling demonstrates that this technique is universally applicable except when the pulsing period is increased to the point where it approaches the period of natural thrust stand motion. Calibration data were obtained using a modified hanging pendulum thrust stand previously used for steady-state thrust measurements. Data were obtained for varying impulse bit at constant pulse frequency and for varying pulse frequency. The two data sets exhibit excellent quantitative agreement with each other as the constant relating average deflection and average thrust match within the errors on the linear regression curve fit of the data. Quantitatively, the error on the calibration coefficient is roughly 1% of the coefficient value.
Pulsed Electric Propulsion Thrust Stand Calibration Method

NASA Technical Reports Server (NTRS)

Wong, Andrea R.; Polzin, Kurt A.; Pearson, J. Boise

2011-01-01

The evaluation of the performance of any propulsion device requires the accurate measurement of thrust. While chemical rocket thrust is typically measured using a load cell, the low thrust levels associated with electric propulsion (EP) systems necessitate the use of much more sensitive measurement techniques. The design and development of electric propulsion thrust stands that employ a conventional hanging pendulum arm connected to a balance mechanism consisting of a secondary arm and variable linkage have been reported in recent publications by Polzin et al. These works focused on performing steady-state thrust measurements and employed a static analysis of the thrust stand response. In the present work, we present a calibration method and data that will permit pulsed thrust measurements using the Variable Amplitude Hanging Pendulum with Extended Range (VAHPER) thrust stand. Pulsed thrust measurements are challenging in general because the pulsed thrust (impulse bit) occurs over a short timescale (typically 1 micros to 1 millisecond) and cannot be resolved directly. Consequently, the imparted impulse bit must be inferred through observation of the change in thrust stand motion effected by the pulse. Pulsed thrust measurements have typically only consisted of single-shot operation. In the present work, we discuss repetition-rate pulsed thruster operation and describe a method to perform these measurements. The thrust stand response can be modeled as a spring-mass-damper system with a repetitive delta forcing function to represent the impulsive action of the thruster.
Thrust Stand for Electric Propulsion Performance Evaluation

NASA Technical Reports Server (NTRS)

Markusic, T. E.; Jones, J. E.; Cox, M. D.

2004-01-01

An electric propulsion thrust stand capable of supporting thrusters with total mass of up to 125 kg and 1 mN to 1 N thrust levels has been developed and tested. The mechanical design features a conventional hanging pendulum arm attached to a balance mechanism that transforms horizontal motion into amplified vertical motion, with accommodation for variable displacement sensitivity. Unlike conventional hanging pendulum thrust stands, the deflection is independent of the length of the pendulum arm, and no reference structure is required at the end of the pendulum. Displacement is measured using a non-contact, optical linear gap displacement transducer. Mechanical oscillations are attenuated using a passive, eddy current damper. An on-board microprocessor-based level control system, which includes a two axis accelerometer and two linear-displacement stepper motors, continuously maintains the level of the balance mechanism - counteracting mechanical %era drift during thruster testing. A thermal control system, which includes heat exchange panels, thermocouples, and a programmable recirculating water chiller, continuously adjusts to varying thermal loads to maintain the balance mechanism temperature, to counteract thermal drifts. An in-situ calibration rig allows for steady state calibration both prior to and during thruster testing. Thrust measurements were carried out on a well-characterized 1 kW Hall thruster; the thrust stand was shown to produce repeatable results consistent with previously published performance data.
Experimental measurement of dolphin thrust generated during a tail stand using DPIV

NASA Astrophysics Data System (ADS)

Wei, Timothy; Fish, Frank; Williams, Terrie; Wu, Vicki; Sherman, Erica; Misfeldt, Mitchel; Ringenberg, Hunter; Rogers, Dylan

2016-11-01

The thrust generated by dolphins doing tail stands was measured using DPIV. The technique entailed measuring vortex strength associated with the tail motion and correlating it to above water video sequences showing the amount of the dolphin's body that was being lifted out of the water. The underlying drivers for this research included: i) understanding the physiology, hydrodynamics and efficiency of dolphin locomotion, ii) developing non-invasive measurement techniques for studying marine swimming and iii) quantifying the actual propulsive capabilities of these animals. Two different bottlenose dolphins at the Long Marine Lab at UC-Santa Cruz were used as test subjects. Application of the Kutta-Joukowski Theorem on measured vortex circulations yielded thrust values that were well correlated with estimates of dolphin body weight being supported above water. This demonstrates that the tail motion can be interpreted as a flapping hydrofoil that can generate a sustained thrust roughly equal to the dolphin's weight. Videos of DPIV measurements overlaid with the dolphins will be presented along with thrust/weight data.
Thrust Stand for Electric Propulsion Performance Evaluation

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.; Dehoyos, Amado; Spaun, Benjamin

2006-01-01

An electric propulsion thrust stand capable of supporting testing of thrusters having a total mass of up to 125 kg and producing thrust levels between 100 microN to 1 N has been developed and tested. The design features a conventional hanging pendulum arm attached to a balance mechanism that converts horizontal deflections produced by the operating thruster into amplified vertical motion of a secondary arm. The level of amplification is changed through adjustment of the location of one of the pivot points linking the system. Response of the system depends on the relative magnitudes of the restoring moments applied by the displaced thruster mass and the twisting torsional pivots connecting the members of the balance mechanism. Displacement is measured using a non-contact, optical linear gap displacement transducer and balance oscillatory motion is attenuated using a passive, eddy-current damper. The thrust stand employs an automated leveling and thermal control system. Pools of liquid gallium are used to deliver power to the thruster without using solid wire connections, which can exert undesirable time-varying forces on the balance. These systems serve to eliminate sources of zero-drift that can occur as the stand thermally or mechanically shifts during the course of an experiment. An in-situ calibration rig allows for steady-state calibration before, during and after thruster operation. Thrust measurements were carried out on a cylindrical Hall thruster that produces mN-level thrust. The measurements were very repeatable, producing results that compare favorably with previously published performance data, but with considerably smaller uncertainty.
Thrust Stand for Vertically Oriented Electric Propulsion Performance Evaluation

NASA Technical Reports Server (NTRS)

Moeller, Trevor; Polzin, Kurt A.

2010-01-01

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally-stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A non-contact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivots with oscillatory motion attenuated by a passive, eddy current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational restoring force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN-level thrusts, while those tests conducted on 200 lbm thruster yielded a resolution of roughly 2.5 micro at thrust levels of 0.5 N and greater.
Thrust stand for vertically oriented electric propulsion performance evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moeller, Trevor; Polzin, Kurt A.

A variation of a hanging pendulum thrust stand capable of measuring the performance of an electric thruster operating in the vertical orientation is presented. The vertical orientation of the thruster dictates that the thruster must be horizontally offset from the pendulum pivot arm, necessitating the use of a counterweight system to provide a neutrally stable system. Motion of the pendulum arm is transferred through a balance mechanism to a secondary arm on which deflection is measured. A noncontact light-based transducer is used to measure displacement of the secondary beam. The members experience very little friction, rotating on twisting torsional pivotsmore » with oscillatory motion attenuated by a passive, eddy-current damper. Displacement is calibrated using an in situ thrust calibration system. Thermal management and self-leveling systems are incorporated to mitigate thermal and mechanical drifts. Gravitational force and torsional spring constants associated with flexure pivots provide restoring moments. An analysis of the design indicates that the thrust measurement range spans roughly four decades, with the stand capable of measuring thrust up to 12 N for a 200 kg thruster and up to approximately 800 mN for a 10 kg thruster. Data obtained from calibration tests performed using a 26.8 lbm simulated thruster indicated a resolution of 1 mN on 100 mN level thrusts, while those tests conducted on a 200 lbm thruster yielded a resolution of roughly 2.5 mN at thrust levels of 0.5 N and greater.« less
A 10 nN resolution thrust-stand for micro-propulsion devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chakraborty, Subha; Courtney, Daniel G.; Shea, Herbert, E-mail: herbert.shea@epfl.ch

We report on the development of a nano-Newton thrust-stand that can measure up to 100 μN thrust from different types of microthrusters with 10 nN resolution. The compact thrust-stand measures the impingement force of the particles emitted from a microthruster onto a suspended plate of size 45 mm × 45 mm and with a natural frequency over 50 Hz. Using a homodyne (lock-in) readout provides strong immunity to facility vibrations, which historically has been a major challenge for nano-Newton thrust-stands. A cold-gas thruster generating up to 50 μN thrust in air was first used to validate the thrust-stand. Better thanmore » 10 nN resolution and a minimum detectable thrust of 10 nN were achieved. Thrust from a miniature electrospray propulsion system generating up to 3 μN of thrust was measured with our thrust-stand in vacuum, and the thrust was compared with that computed from beam diagnostics, obtaining agreement within 50 nN to 150 nN. The 10 nN resolution obtained from this thrust-stand matches that from state-of-the-art nano-Newton thrust-stands, which measure thrust directly from the thruster by mounting it on a moving arm (but whose natural frequency is well below 1 Hz). The thrust-stand is the first of its kind to demonstrate less than 3 μN resolution by measuring the impingement force, making it capable of measuring thrust from different types of microthrusters, with the potential of easy upscaling for thrust measurement at much higher levels, simply by replacing the force sensor with other force sensors.« less
A 10 nN resolution thrust-stand for micro-propulsion devices

NASA Astrophysics Data System (ADS)

Chakraborty, Subha; Courtney, Daniel G.; Shea, Herbert

2015-11-01

We report on the development of a nano-Newton thrust-stand that can measure up to 100 μN thrust from different types of microthrusters with 10 nN resolution. The compact thrust-stand measures the impingement force of the particles emitted from a microthruster onto a suspended plate of size 45 mm × 45 mm and with a natural frequency over 50 Hz. Using a homodyne (lock-in) readout provides strong immunity to facility vibrations, which historically has been a major challenge for nano-Newton thrust-stands. A cold-gas thruster generating up to 50 μN thrust in air was first used to validate the thrust-stand. Better than 10 nN resolution and a minimum detectable thrust of 10 nN were achieved. Thrust from a miniature electrospray propulsion system generating up to 3 μN of thrust was measured with our thrust-stand in vacuum, and the thrust was compared with that computed from beam diagnostics, obtaining agreement within 50 nN to 150 nN. The 10 nN resolution obtained from this thrust-stand matches that from state-of-the-art nano-Newton thrust-stands, which measure thrust directly from the thruster by mounting it on a moving arm (but whose natural frequency is well below 1 Hz). The thrust-stand is the first of its kind to demonstrate less than 3 μN resolution by measuring the impingement force, making it capable of measuring thrust from different types of microthrusters, with the potential of easy upscaling for thrust measurement at much higher levels, simply by replacing the force sensor with other force sensors.
High-power, null-type, inverted pendulum thrust stand.

PubMed

Xu, Kunning G; Walker, Mitchell L R

2009-05-01

This article presents the theory and operation of a null-type, inverted pendulum thrust stand. The thrust stand design supports thrusters having a total mass up to 250 kg and measures thrust over a range of 1 mN to 5 N. The design uses a conventional inverted pendulum to increase sensitivity, coupled with a null-type feature to eliminate thrust alignment error due to deflection of thrust. The thrust stand position serves as the input to the null-circuit feedback control system and the output is the current to an electromagnetic actuator. Mechanical oscillations are actively damped with an electromagnetic damper. A closed-loop inclination system levels the stand while an active cooling system minimizes thermal effects. The thrust stand incorporates an in situ calibration rig. The thrust of a 3.4 kW Hall thruster is measured for thrust levels up to 230 mN. The uncertainty of the thrust measurements in this experiment is +/-0.6%, determined by examination of the hysteresis, drift of the zero offset and calibration slope variation.
Design and evaluation of thrust vectored nozzles using a multicomponent thrust stand

NASA Technical Reports Server (NTRS)

Carpenter, Thomas W.; Blattner, Ernest W.; Stagner, Robert E.; Contreras, Juanita; Lencioni, Dennis; Mcintosh, Greg

1990-01-01

Future aircraft with the capability of short takeoff and landing, and improved maneuverability especially in the post-stall flight regime will incorporate exhaust nozzles which can be thrust vectored. In order to conduct thrust vector research in the Mechanical Engineering Department at Cal Poly, a program was planned with two objectives; design and construct a multicomponent thrust stand for the specific purpose of measuring nozzle thrust vectors; and to provide quality low moisture air to the thrust stand for cold flow nozzle tests. The design and fabrication of the six-component thrust stand was completed. Detailed evaluation tests of the thrust stand will continue upon the receipt of one signal conditioning option (-702) for the Fluke Data Acquisition System. Preliminary design of thrust nozzles with air supply plenums were completed. The air supply was analyzed with regard to head loss. Initial flow visualization tests were conducted using dual water jets.
Laser Plasma Microthruster Performance Evaluation

NASA Astrophysics Data System (ADS)

Luke, James R.; Phipps, Claude R.

2003-05-01

The micro laser plasma thruster (μLPT) is a sub-kilogram thruster that is capable of meeting the Air Force requirements for the Attitude Control System on a 100-kg class small satellite. The μLPT uses one or more 4W diode lasers to ablate a solid fuel, producing a jet of hot gas or plasma which creates thrust with a high thrust/power ratio. A pre-prototype continuous thrust experiment has been constructed and tested. The continuous thrust experiment uses a 505 mm long continuous loop fuel tape, which consists of a black laser-absorbing fuel material on a transparent plastic substrate. When the laser is operated continuously, the exhaust plume and thrust vector are steered in the direction of the tape motion. Thrust steering can be avoided by pulsing the laser. A torsion pendulum thrust stand has been constructed and calibrated. Many fuel materials and substrates have been tested. Best performance from a non-energetic fuel material was obtained with black polyvinyl chloride (PVC), which produced an average of 70 μN thrust and coupling coefficient (Cm) of 190 μN/W. A proprietary energetic material was also tested, in which the laser initiates a non-propagating detonation. This material produced 500 μN of thrust.
Nanonewton thrust measurement of photon pressure propulsion using semiconductor laser

NASA Astrophysics Data System (ADS)

Iwami, K.; Akazawa, Taku; Ohtsuka, Tomohiro; Nishida, Hiroyuki; Umeda, Norihiro

2011-09-01

To evaluate the thrust produced by photon pressure emitted from a 100 W class continuous-wave semiconductor laser, a torsion-balance precise thrust stand is designed and tested. Photon emission propulsion using semiconductor light sources attract interests as a possible candidate for deep-space propellant-less propulsion and attitude control system. However, the thrust produced by photon emission as large as several ten nanonewtons requires precise thrust stand. A resonant method is adopted to enhance the sensitivity of the biflier torsional-spring thrust stand. The torsional spring constant and the resonant of the stand is 1.245 × 10-3 Nm/rad and 0.118 Hz, respectively. The experimental results showed good agreement with the theoretical estimation. The thrust efficiency for photon propulsion was also defined. A maximum thrust of 499 nN was produced by the laser with 208 W input power (75 W of optical output) corresponding to a thrust efficiency of 36.7%. The minimum detectable thrust of the stand was estimated to be 2.62 nN under oscillation at a frequency close to resonance.
PPT Thrust Stand

NASA Technical Reports Server (NTRS)

Haag, Thomas W.

1995-01-01

A torsional-type thrust stand has been designed and built to test Pulsed Plasma Thrusters (PPT's) in both single shot and repetitive operating modes. Using this stand, momentum per pulse was determined strictly as a function of thrust stand deflection, spring constant, and natural frequency. No empirical corrections were required. The accuracy of the method was verified using a swinging impact pendulum. Momentum transfer data between the thrust stand and the pendulum were consistent to within 1%. Following initial calibrations, the stand was used to test a Lincoln Experimental Satellite (LES-8/9) thruster. The LES-8/9 system had a mass of approximately 7.5 kg, with a nominal thrust to weight ratio of 1.3 x 10(exp -5). A total of 34 single shot thruster pulses were individually measured. The average impulse bit per pulse was 266 microN-s, which was slightly less than the value of 300 microN-s published in previous reports on this device. Repetitive pulse measurements were performed similar to ordinary steady-state thrust measurements. The thruster was operated for 30 minutes at a repetition rate of 132 pulses per minute and yielded an average thrust of 573 microN. Using average thrust, the average impulse bit per pulse was estimated to be 260 microN-s, which was in agreement with the single shot data. Zero drift during the repetitive pulse test was found to be approximately 1% of the measured thrust.
A microNewton thrust stand for average thrust measurement of pulsed microthruster.

PubMed

Zhou, Wei-Jing; Hong, Yan-Ji; Chang, Hao

2013-12-01

A torsional thrust stand has been developed for the study of the average thrust for microNewton pulsed thrusters. The main body of the thrust stand mainly consists of a torsional balance, a pair of flexural pivots, a capacitive displacement sensor, a calibration assembly, and an eddy current damper. The behavior of the stand was thoroughly studied. The principle of thrust measurement was analyzed. The average thrust is determined as a function of the average equilibrium angle displacement of the balance and the spring stiffness. The thrust stand has a load capacity up to 10 kg, and it can theoretically measure the force up to 609.6 μN with a resolution of 24.4 nN. The static calibrations were performed based on the calibration assembly composed of the multiturn coil and the permanent magnet. The calibration results demonstrated good repeatability (less than 0.68% FSO) and good linearity (less than 0.88% FSO). The assembly of the multiturn coil and the permanent magnet was also used as an exciter to simulate the microthruster to further research the performance of the thrust stand. Three sets of force pulses at 17, 33.5, and 55 Hz with the same amplitude and pulse width were tested. The repeatability error at each frequency was 7.04%, 1.78%, and 5.08%, respectively.
Electromagnetic calibration system for sub-micronewton torsional thrust stand

NASA Astrophysics Data System (ADS)

Lam, J. K.; Koay, S. C.; Cheah, K. H.

2017-12-01

It is critical for a micropropulsion system to be evaluated. Thrust stands are widely recognised as the instrument to complete such tasks. This paper presents the development of an alternative electromagnetic calibration technique for thrust stands. Utilising the commercially made voice coils and permanent magnets, the proposed system is able to generate repeatable and also consistent steady-state calibration forces at over four orders of magnitude (30 - 23000 μN). The system is then used to calibrate a custom-designed torsional thrust stand, where its inherent ability in ease of setup is well demonstrated.
Revolutionizing Space Propulsion Through the Characterization of Iodine as Fuel for Hall-Effect Thrusters

DTIC Science & Technology

2011-03-01

for controlled thruster operation at varying conditions. An inverted pendulum was used to take thrust measurements. Thrust to power ratio, anode...for comparison will include thrust, T. Thrust 21 can be measured by a sensitive inverted pendulum thrust stand. Specific impulse would be...to this pressure. III.4 Diagnostic Equipment The instrument used to take thrust measurements was the Busek T8 inverted pendulum thrust stand [13
Development of a Transient Thrust Stand with Sub-Millisecond Resolution

NASA Astrophysics Data System (ADS)

Spells, Corbin Fraser

The transient thrust stand has been developed to offer 0.1 ms time resolved thrust measurements for the characterization of mono-propellant thrusters for spacecraft applications. Results demonstrated that the system was capable of obtaining dynamic thrust profiles within 5 % and 0.1 ms. Measuring and improving the thrust performance of mono-propellant thrusters will require 1 ms time resolved forces to observe shot-to-shot variations, oscillations, and minimum impulse bits. To date, no thrust stand is capable of measuring up to 22 N forces with a time response of up to 10 kHz. Calibration forces up to 22 N with a frequency response greater than 0.1 ms were obtained using voice coil actuators. Steady state and low frequency measurements were obtained using displacement and velocity sensors and were combined with high frequency vibration modes measured using several accelerometers along the thrust stand arm. The system uses a predictor-based subspace algorithm to obtain a high order state space model of the thrust stand capable of defining the high frequency vibration modes. The high frequency vibration modes are necessary to provide the time response of 0.1 ms. Thruster forces are estimated using an augmented Kalman filter to combine sensor traces from four accelerometers, a velocity sensor, and displacement transducer. Combining low frequency displacement data with high frequency acceleration measurements provides accurate force data across a broad time domain. The transient thrust stand uses a torsional pendulum configuration to minimize influence from external vibration and achieve high force resolution independent of thruster weight.
Development of a two-dimensional dual pendulum thrust stand for Hall thrusters.

PubMed

Nagao, N; Yokota, S; Komurasaki, K; Arakawa, Y

2007-11-01

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors [axial and horizontal (transverse) direction thrusts] of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%) in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of +/-2.3 degrees was measured with the error of +/-0.2 degrees under the typical operating conditions for the thruster.

A-1 Test Stand work

NASA Technical Reports Server (NTRS)

2010-01-01

Employees at NASA's John C. Stennis Space Center work to maneuver a structural steam beam into place on the A-1 Test Stand on Jan. 13. The beam was one of several needed to form the thrust takeout structure that will support a new thrust measurement system being installed on the stand for future rocket engine testing. Once lifted onto the stand, the beams had to be hoisted into place through the center of the test stand, with only two inches of clearance on each side. The new thrust measurement system represents a state-of-the-art upgrade from the equipment installed more than 40 years ago when the test stand was first constructed.
rf power system for thrust measurements of a helicon plasma source.

PubMed

Kieckhafer, Alexander W; Walker, Mitchell L R

2010-07-01

A rf power system has been developed, which allows the use of rf plasma devices in an electric propulsion test facility without excessive noise pollution in thruster diagnostics. Of particular importance are thrust stand measurements, which were previously impossible due to noise. Three major changes were made to the rf power system: first, the cable connection was changed from a balanced transmission line to an unbalanced coaxial line. Second, the rf power cabinet was placed remotely in order to reduce vibration-induced noise in the thrust stand. Finally, a relationship between transmission line length and rf was developed, which allows good transmission of rf power from the matching network to the helicon antenna. The modified system was tested on a thrust measurement stand and showed that rf power has no statistically significant contribution to the thrust stand measurement.
Development of a Thrust Stand to Meet LISA Mission Requirements

NASA Technical Reports Server (NTRS)

Willis, William D., III; Zakrzwski, Charles M.; Merkowitz, Stephen M.

2002-01-01

A thrust stand has been built to measure the force-noise produced by electrostatic micro-Newton (muN) thrusters. The LISA mission's Disturbance Reduction System (DRS) requires thrusters that are capable of producing continuous thrust levels between 1-100 muN with a resolution of 0.1 muN. The stationary force-noise produced by these thrusters must not exceed 0.1 muN/dHz in the measurement bandwidth 10(exp -4) to 1 Hz. The LISA Thrust Stand (LTS) is a torsion-balance type thrust stand designed to meet the following requirements: stationary force-noise measurements from l0( -4) to 1 Hz with 0.1 muN/dHz sensitivity, absolute thrust measurements from 1-100 muN with better than 0.1 muN resolution, and dynamic thruster response from to 10 Hz. The LTS employs a unique vertical configuration, autocollimator for angular position measurements, and electrostatic actuators that are used for dynamic pendulum control and null-mode measurements. Force-noise levels are measured indirectly by characterizing the thrust stand as a spring-mass system. The LTS was initially designed to test the indium FEEP thruster developed by the Austrian Research Center in Seibersdorf (ARCS), but can be modified for testing other thrusters of this type.
Development of A Thrust Stand to Meet LISA Mission Requirements

NASA Technical Reports Server (NTRS)

Willis, William D., III; Zakrzwski, C. M.; Bauer, Frank H. (Technical Monitor)

2002-01-01

A thrust stand has been built and tested that is capable of measuring the force-noise produced by electrostatic micro-Newton (micro-Newton) thrusters. The LISA mission's Disturbance Reduction System (DRS) requires thrusters that are capable of producing continuous thrust levels between 1-100 micro-Newton with a resolution of 0.1 micro-Newton. The stationary force-noise produced by these thrusters must not exceed 0.1 pN/4Hz in a 10 Hz bandwidth. The LISA Thrust Stand (LTS) is a torsion-balance type thrust stand designed to meet the following requirements: stationary force-noise measurements from 10(exp-4) to 1 Hz with 0.1 micro-Newton resolution, absolute thrust measurements from 1-100 micro-Newton with better than 0.1 micro-Newton resolution, and dynamic thruster response from 10(exp -4) to 10 Hz. The ITS employs a unique vertical configuration, autocollimator for angular position measurements, and electrostatic actuators that are used for dynamic pendulum control and null-mode measurements. Force-noise levels are measured indirectly by characterizing the thrust stand as a spring-mass system. The LTS was initially designed to test the indium FEEP thruster developed by the Austrian Research Center in Seibersdorf (ARCS), but can be modified for testing other thrusters of this type.
Development of a two-dimensional dual pendulum thrust stand for Hall thrusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagao, N.; Yokota, S.; Komurasaki, K.

A two-dimensional dual pendulum thrust stand was developed to measure thrust vectors (axial and horizontal (transverse) direction thrusts) of a Hall thruster. A thruster with a steering mechanism is mounted on the inner pendulum, and thrust is measured from the displacement between inner and outer pendulums, by which a thermal drift effect is canceled out. Two crossover knife-edges support each pendulum arm: one is set on the other at a right angle. They enable the pendulums to swing in two directions. Thrust calibration using a pulley and weight system showed that the measurement errors were less than 0.25 mN (1.4%)more » in the main thrust direction and 0.09 mN (1.4%) in its transverse direction. The thrust angle of the thrust vector was measured with the stand using the thruster. Consequently, a vector deviation from the main thrust direction of {+-}2.3 deg. was measured with the error of {+-}0.2 deg. under the typical operating conditions for the thruster.« less
rf power system for thrust measurements of a helicon plasma source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kieckhafer, Alexander W.; Walker, Mitchell L. R.

2010-07-15

A rf power system has been developed, which allows the use of rf plasma devices in an electric propulsion test facility without excessive noise pollution in thruster diagnostics. Of particular importance are thrust stand measurements, which were previously impossible due to noise. Three major changes were made to the rf power system: first, the cable connection was changed from a balanced transmission line to an unbalanced coaxial line. Second, the rf power cabinet was placed remotely in order to reduce vibration-induced noise in the thrust stand. Finally, a relationship between transmission line length and rf was developed, which allows goodmore » transmission of rf power from the matching network to the helicon antenna. The modified system was tested on a thrust measurement stand and showed that rf power has no statistically significant contribution to the thrust stand measurement.« less
Recommended Practices in Thrust Measurements

DTIC Science & Technology

2013-10-01

Turin.5,38 This stand consists of two BeCu plates which hang from flexible BeCu mounts on a rigid block of Zerodur c, a material with a very low coe...2013 Figure 4. Example of a state-of-the-art hanging pendulum thrust stand. 38 Two spherical mirrors mounted on the plates form an optical cavity for...the Zerodur frame. Temperature control and careful choice of materials were used to minimize and correct for thermal drift. 2. Thrust Stand Performance
Derivation of the Data Reduction Equations for the Calibration of the Six-component Thrust Stand in the CE-22 Advanced Nozzle Test Facility

NASA Technical Reports Server (NTRS)

Wong, Kin C.

2003-01-01

This paper documents the derivation of the data reduction equations for the calibration of the six-component thrust stand located in the CE-22 Advanced Nozzle Test Facility. The purpose of the calibration is to determine the first-order interactions between the axial, lateral, and vertical load cells (second-order interactions are assumed to be negligible). In an ideal system, the measurements made by the thrust stand along the three coordinate axes should be independent. For example, when a test article applies an axial force on the thrust stand, the axial load cells should measure the full magnitude of the force, while the off-axis load cells (lateral and vertical) should read zero. Likewise, if a lateral force is applied, the lateral load cells should measure the entire force, while the axial and vertical load cells should read zero. However, in real-world systems, there may be interactions between the load cells. Through proper design of the thrust stand, these interactions can be minimized, but are hard to eliminate entirely. Therefore, the purpose of the thrust stand calibration is to account for these interactions, so that necessary corrections can be made during testing. These corrections can be expressed in the form of an interaction matrix, and this paper shows the derivation of the equations used to obtain the coefficients in this matrix.
TMS delivered for A-3 Test Stand

NASA Image and Video Library

2010-03-17

A state-of-the-art thrust measurement system for the A-3 Test Stand under construction at NASA's John C. Stennis Space Center was delivered March 17. Once completed, the A-3 stand (seen in background) will allow simulated high-altitude testing on the next generation of rocket engines for America's space program. Work on the stand began in 2007, with activation scheduled for 2012. The stand is the first major test structure to be built at Stennis since the 1960s. The recently delivered TMS was fabricated by Thrust Measurement Systems in Illinois. It is an advanced calibration system capable of measuring vertical and horizontal thrust loads with an accuracy within 0.15 percent at 225,000 pounds.
Directed energy deflection laboratory measurements

NASA Astrophysics Data System (ADS)

Brashears, Travis; Lubin, Phillip; Hughes, Gary B.; Meinhold, Peter; Suen, Jonathan; Batliner, Payton; Motta, Caio; Griswold, Janelle; Kangas, Miikka; Johansson, Isbella; Alnawakhtha, Yusuf; Prater, Kenyon; Lang, Alex; Madajian, Jonathan

2015-09-01

We report on laboratory studies of the effectiveness of directed energy planetary defense as a part of the DESTAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR [1][5][6] and DE-STARLITE [2][5][6] are directed energy "stand-off" and "stand-on" programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid's orbit. In a series of papers, we have developed a theoretical basis and described numerical simulations for determining the thrust produced by material evaporating from the surface of an asteroid [1][2][3][4][5][6]. In the DE-STAR concept, the asteroid itself is used as the deflection "propellant". This study presents results of experiments designed to measure the thrust created by evaporation from a laser directed energy spot. We constructed a vacuum chamber to simulate space conditions, and installed a torsion balance that holds an "asteroid" sample. The sample is illuminated with a fiber array laser with flux levels up to 60 MW/m2 which allows us to simulate a mission level flux but on a small scale. We use a separate laser as well as a position sensitive centroid detector to readout the angular motion of the torsion balance and can thus determine the thrust. We compare the measured thrust to the models. Our theoretical models indicate a coupling coefficient well in excess of 100 μN/Woptical, though we assume a more conservative value of 80 μN/Woptical and then degrade this with an optical "encircled energy" efficiency of 0.75 to 60 μN/Woptical in our deflection modeling. Our measurements discussed here yield about 45 μN/Wabsorbed as a reasonable lower limit to the thrust per optical watt absorbed.
Thrust stand evaluation of engine performance improvement algorithms in an F-15 airplane

NASA Technical Reports Server (NTRS)

Conners, Timothy R.

1992-01-01

An investigation is underway to determine the benefits of a new propulsion system optimization algorithm in an F-15 airplane. The performance seeking control (PSC) algorithm optimizes the quasi-steady-state performance of an F100 derivative turbofan engine for several modes of operation. The PSC algorithm uses an onboard software engine model that calculates thrust, stall margin, and other unmeasured variables for use in the optimization. As part of the PSC test program, the F-15 aircraft was operated on a horizontal thrust stand. Thrust was measured with highly accurate load cells. The measured thrust was compared to onboard model estimates and to results from posttest performance programs. Thrust changes using the various PSC modes were recorded. Those results were compared to benefits using the less complex highly integrated digital electronic control (HIDEC) algorithm. The PSC maximum thrust mode increased intermediate power thrust by 10 percent. The PSC engine model did very well at estimating measured thrust and closely followed the transients during optimization. Quantitative results from the evaluation of the algorithms and performance calculation models are included with emphasis on measured thrust results. The report presents a description of the PSC system and a discussion of factors affecting the accuracy of the thrust stand load measurements.
Immediate effects of bilateral manipulation of talocrural joints on standing stability in healthy subjects.

PubMed

Alburquerque-Sendín, Francisco; Fernández-de-las-Peñas, César; Santos-del-Rey, Miguel; Martín-Vallejo, Francisco Javier

2009-02-01

The purpose of this study was to investigate the immediate effects of bilateral talocrural joint manipulation on standing stability in healthy subjects. Sixty-two healthy subjects, 16 males and 46 females, aged from 18 to 32 years old (mean: 21+/-3 years old) participated in the study. Subjects were randomly divided into two groups: an intervention group (n=32), who received manipulation of bilateral talocrural joints and a control group (n=30) which did not receive any intervention. Baropodometric and stabilometric evaluations were assessed pre- and 5 min post-intervention by an assessor blinded to the treatment allocation. Intra-group and inter-group comparisons were analysed using appropriate parametric tests. The results indicated that changes on the X coordinate range, length of motion, and mean speed approximated to statistical significance (P=0.06), and changes on the Y coordinate range reached statistical significance (P=0.02). Average X and Y motions, and anterior-posterior or lateral velocities did not show significant differences. Our results showed that bilateral thrust manipulation of the talocrural joint did not modify standing stability, that is, the behavioural pattern of the projection of the centre of pressure, in healthy subjects.
Comparison of straight and 15 degree vectored nozzles using a six component thrust stand

NASA Technical Reports Server (NTRS)

Carpenter, Thomas W.; Flake, Scott

1991-01-01

This project compared the forces and moments produced by straight and 15 degree vectored nozzles. Using the six component thrust stand in the engines laboratory at California Polytechnic State University, several trials were performed. This data was then reduced using first a computer program and then later an electronic spreadsheet. This reduced data was graphed and compared. As a result of these comparisons some unexpected forces were discovered. Several more tests were run including a zero thrust test and a statistical comparison were done to discover the source of these discrepancies. As a direct result several nozzle changes were made and significant revisions to the thrust stand are being made.
4. COMPLETE X15 VEHICLE TEST STAND, DETAIL OF THRUST MOUNTING ...

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

4. COMPLETE X-15 VEHICLE TEST STAND, DETAIL OF THRUST MOUNTING STRUCTURE AT ENGINE END OF PLANE. - Edwards Air Force Base, X-15 Engine Test Complex, Rocket Engine & Complete X-15 Vehicle Test Stands, Rogers Dry Lake, east of runway between North Base & South Base, Boron, Kern County, CA
Characterization of Space Shuttle Reusable Rocket Motor Static Test Stand Thrust Measurements

NASA Technical Reports Server (NTRS)

Cook, Mart L.; Gruet, Laurent; Cash, Stephen F. (Technical Monitor)

2003-01-01

Space Shuttle Reusable Solid Rocket Motors (RSRM) are static tested at two ATK Thiokol Propulsion facilities in Utah, T-24 and T-97. The newer T-97 static test facility was recently upgraded to allow thrust measurement capability. All previous static test motor thrust measurements have been taken at T-24; data from these tests were used to characterize thrust parameters and requirement limits for flight motors. Validation of the new T-97 thrust measurement system is required prior to use for official RSRM performance assessments. Since thrust cannot be measured on RSRM flight motors, flight motor measured chamber pressure and a nominal thrust-to-pressure relationship (based on static test motor thrust and pressure measurements) are used to reconstruct flight motor performance. Historical static test and flight motor performance data are used in conjunction with production subscale test data to predict RSRM performance. The predicted motor performance is provided to support Space Shuttle trajectory and system loads analyses. Therefore, an accurate nominal thrust-to-pressure (F/P) relationship is critical for accurate RSRM flight motor performance and Space Shuttle analyses. Flight Support Motors (FSM) 7, 8, and 9 provided thrust data for the validation of the T-97 thrust measurement system. The T-97 thrust data were analyzed and compared to thrust previously measured at T-24 to verify measured thrust data and identify any test-stand bias. The T-97 FIP data were consistent and within the T-24 static test statistical family expectation. The FSMs 7-9 thrust data met all NASA contract requirements, and the test stand is now verified for future thrust measurements.
A torsion balance for impulse and thrust measurements of micro-Newton thrusters

NASA Astrophysics Data System (ADS)

Yang, Yuan-Xia; Tu, Liang-Cheng; Yang, Shan-Qing; Luo, Jun

2012-01-01

This paper reports the performance of a torsion-type thrust stand suitable for studies of micro-Newton thrusters, which is developed for ground testing the micro-Newton thruster in Chinese Test of the Equivalence Principle with Optical readout space mission. By virtue of specially suspending design and precise assembly of torsion balance configuration, the thrust stand with load capacity up to several kilograms is able to measure the impulse bit up to 1350 μNs with a resolution of 0.47 μNs, and the average thrust up to 264 μN with a resolution of 0.09 μN in both open and close loop operation. A pulsed plasma thruster, the preliminary prototype developed for Chinese TEPO space mission, is tested by the thrust stand, and the results reveal that the average impulse bit per pulse is measured to be 58.4 μNs with a repeatability of about 5%.
Varus Thrust and Knee Frontal Plane Dynamic Motion in Persons with Knee Osteoarthritis

PubMed Central

Chang, Alison H.; Chmiel, Joan S.; Moisio, Kirsten C.; Almagor, Orit; Zhang, Yunhui; Cahue, September; Sharma, Leena

2013-01-01

Objective Varus thrust visualized during walking is associated with a greater medial knee and an increased risk of medial knee osteoarthritis (OA) progression. Little is known about varus thrust presence determined by visual observation relates to quantitative gait kinematic We hypothesized that varus thrust presence is associated with greater knee frontal plane dynamic movement during the stance phase of gait. Methods Participants had knee OA in at least one knee. Trained examiners assessed participants for varus thrust presence during ambulation. Frontal plane knee motion during ambulation captured using external passive reflective markers and an 8-camera motion analysis system. To examine the cross-sectional relationship between varus thrust and frontal plane knee motion, used multivariable regression models with the quantitative motion measures as dependent variables and varus thrust (present/absent) as predictor; models were adjusted for age, gender, BMI, gait speed, and knee static alignment. Results 236 persons [mean BMI: 28.5 kg/m2 (SD 5.5), mean age: 64.9 years (SD 10.4), 75.8% women] contributing 440 knees comprised the study sample. 82 knees (18.6%) had definite varus thrust. Knees with varus thrust had greater peak varus angle and greater peak varus angular velocity during stance than knees without varus thrust (mean differences 0.90° and 6.65°/sec, respectively). These patterns remained significant after adjusting for age, gender, BMI, gait speed, and knee static alignment. Conclusion Visualized varus thrust during walking was associated with a greater peak knee varus angular velocity and a greater peak knee varus angle during stance phase of gait. PMID:23948980
The effect of high tibial osteotomy on osteoarthritis of the knee : Clinical and histological observations.

PubMed

Koshino, T; Tsuchiya, K

1979-03-01

High tibial osteotomies were performed on 136 osteoarthritic knees for correction of varus deformity. Before osteotomy all patients experienced moderate or severe pain, and the knees showed lateral thrust on weight-bearing. The patients were followed up for one to five years. Marked relief of pain was obtained in 112 knees, and the patients were satisfied with the result of operation in 122. These painless knees showed no lateral thrust, and in the majority the deformity had been adequately corrected, with post-operative femoro-tibial angles (standing) ranging from 165° to 174°. Four of 28 knees with femoro-tibial angles of 175° to 179°, when measured one year after operation, showed recurrence of varus deformity three years after osteotomy. Preoperative ranges of knee motion were well maintained after osteotomy even when arthrotomy had also been undertaken. Intra-articular assessment in two patients, several years after operation, showed that the most degenerated portions of the articular surface were completely covered by a fibrocartilagenous layer, with no bare bone.High tibial osteotomy is most effective in osteoarthritic knees with varus deformity, when correction is made to a femoro-tibial angle (standing) of 170° (10° valgus).
The effect of high tibial osteotomy on osteoarthritis of the knee. Clinical and histological observations.

PubMed

Koshino, T; Tsuchiya, K

1979-01-01

High tibial osteotomies were performed on 136 osteoarthritic knees for correction of varus deformity. Before osteotomy all patients experienced moderate or severe pain, and the knees showed lateral thrust on weight-bearing. The patients were followed up for one to five years. Marked relief of pain was obtained in 112 knees, and the patients were satisfied with the result of operation in 122. These painless knees showed no lateral thrust, and in the majority the deformity had been adequately corrected, with post-operative femoro-tibial angles (standing) ranging from 165 degrees to 174 degrees. Four of 28 knees with femoro-tibial angles of 175 degrees to 179 degrees, when measured one year after operation, showed recurrence of varus deformity three years after osteotomy. Preoperative ranges of knee motion were well maintained after osteotomy even when arthrotomy had also been undertaken. Intra-articular assessment in two patients, several years after operation, showed that the most degenerated portions of the articular surface were completely covered by a fibrocartilagenous layer, with no bare bone. High tibial osteotomy is most effective in osteoarthritic knees with varus deformity, when correction is made to a femoro-tibial angle (standing) of 170 degrees (10 degrees valgus).
10. DETAIL SHOWING THRUST MEASURING SYSTEM. Looking up from the ...

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

10. DETAIL SHOWING THRUST MEASURING SYSTEM. Looking up from the test stand deck to east. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Orbital and angular motion construction for low thrust interplanetary flight

NASA Astrophysics Data System (ADS)

Yelnikov, R. V.; Mashtakov, Y. V.; Ovchinnikov, M. Yu.; Tkachev, S. S.

2016-11-01

Low thrust interplanetary flight is considered. Firstly, the fuel-optimal control is found. Then the angular motion is synthesized. This motion provides the thruster tracking of the required by optimal control direction. And, finally, reaction wheel control law for tracking this angular motion is proposed and implemented. The numerical example is given and total operation time for thrusters is found. Disturbances from solar pressure, thrust eccentricity, inaccuracy of reaction wheels installation and errors of inertia tensor are taken into account.
Varus thrust and knee frontal plane dynamic motion in persons with knee osteoarthritis.

PubMed

Chang, A H; Chmiel, J S; Moisio, K C; Almagor, O; Zhang, Y; Cahue, S; Sharma, L

2013-11-01

Varus thrust visualized during walking is associated with a greater medial knee load and an increased risk of medial knee osteoarthritis (OA) progression. Little is known about how varus thrust presence determined by visual observation relates to quantitative gait kinematic data. We hypothesized that varus thrust presence is associated with greater knee frontal plane dynamic movement during the stance phase of gait. Participants had knee OA in at least one knee. Trained examiners assessed participants for varus thrust presence during ambulation. Frontal plane knee motion during ambulation was captured using external passive reflective markers and an 8-camera motion analysis system. To examine the cross-sectional relationship between varus thrust and frontal plane knee motion, we used multivariable regression models with the quantitative motion measures as dependent variables and varus thrust (present/absent) as predictor; models were adjusted for age, gender, body mass index (BMI), gait speed, and knee static alignment. 236 persons [mean BMI: 28.5 kg/m(2) (standard deviation (SD) 5.5), mean age: 64.9 years (SD 10.4), 75.8% women] contributing 440 knees comprised the study sample. 82 knees (18.6%) had definite varus thrust. Knees with varus thrust had greater peak varus angle and greater peak varus angular velocity during stance than knees without varus thrust (mean differences 0.90° and 6.65°/s, respectively). These patterns remained significant after adjusting for age, gender, BMI, gait speed, and knee static alignment. Visualized varus thrust during walking was associated with a greater peak knee varus angular velocity and a greater peak knee varus angle during stance phase of gait. Copyright © 2013 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
A-1 Test Stand work

NASA Technical Reports Server (NTRS)

2010-01-01

A structural steel beam to support the new thrust measurement system on the A-1 Test Stand at NASA's John C. Stennis Space Center is lifted to waiting employees for installation. The beam is part of the thrust takeout structure needed to support the new measurement system. Four such beams have been installed at the stand in preparation for installation of the system in upcoming weeks. Operators are preparing the stand for testing the next generation of rocket engines for the U.S. space program.
Directed energy deflection laboratory measurements of common space based targets

NASA Astrophysics Data System (ADS)

Brashears, Travis; Lubin, Philip; Hughes, Gary B.; Meinhold, Peter; Batliner, Payton; Motta, Caio; Madajian, Jonathan; Mercer, Whitaker; Knowles, Patrick

2016-09-01

We report on laboratory studies of the effectiveness of directed energy planetary defense as a part of the DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR and DE-STARLITE are directed energy "stand-off" and "stand-on" programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid's orbit. In a series of papers, we have developed a theoretical basis and described numerical simulations for determining the thrust produced by material evaporating from the surface of an asteroid. In the DESTAR concept, the asteroid itself is used as the deflection "propellant". This study presents results of experiments designed to measure the thrust created by evaporation from a laser directed energy spot. We constructed a vacuum chamber to simulate space conditions, and installed a torsion balance that holds a common space target sample. The sample is illuminated with a fiber array laser with flux levels up to 60 MW/m2 , which allows us to simulate a mission level flux but on a small scale. We use a separate laser as well as a position sensitive centroid detector to readout the angular motion of the torsion balance and can thus determine the thrust. We compare the measured thrust to the models. Our theoretical models indicate a coupling coefficient well in excess of 100 μN/Woptical, though we assume a more conservative value of 80 μN/Woptical and then degrade this with an optical "encircled energy" efficiency of 0.75 to 60 μN/Woptical in our deflection modeling. Our measurements discussed here yield about 45 μN/Wabsorbed as a reasonable lower limit to the thrust per optical watt absorbed. Results vary depending on the material tested and are limited to measurements of 1 axis, so further tests must be performed.
Directed Energy Deflection Laboratory Measurements of Asteroids and Space Debris

NASA Astrophysics Data System (ADS)

Brashears, T.; Lubin, P. M.

2016-12-01

We report on laboratory studies of the effectiveness of directed energy planetary and space defense as a part of the DE-STAR (Directed Energy System for Targeting of Asteroids and exploRation) program. DE-STAR [1][5][6] and DE-STARLITE [2][5][6] are directed energy "stand-off" and "stand-on" programs, respectively. These systems consist of a modular array of kilowatt-class lasers powered by photovoltaics, and are capable of heating a spot on the surface of an asteroid to the point of vaporization. Mass ejection, as a plume of evaporated material, creates a reactionary thrust capable of diverting the asteroid's orbit. In a series of papers, we have developed a theoretical basis and described numerical simulations for determining the thrust produced by material evaporating from the surface of an asteroid [1][2][3][4][5][6]. In the DE-STAR concept, the asteroid itself is used as the deflection "propellant". This study presents results of experiments designed to measure the thrust created by evaporation from a laser directed energy spot. We constructed a vacuum chamber to simulate space conditions, and installed a torsion balance that holds an "asteroid" or a space debris sample. The sample is illuminated with a fiber array laser with flux levels up to 60 MW/m2 which allows us to simulate a mission level flux but on a small scale. We use a separate laser as well as a position sensitive centroid detector to readout the angular motion of the torsion balance and can thus determine the thrust. We compare the measured thrust to the models. Our theoretical models indicate a coupling coefficient well in excess of 100 µN/Woptical, though we assume a more conservative value of 80 µN/Woptical and then degrade this with an optical "encircled energy" efficiency of 0.75 to 60 µN/Woptical in our deflection modeling. Our measurements discussed here yield about 60 µN/Wabsorbed as a reasonable lower limit to the thrust per optical watt absorbed.
Test stand for precise measurement of impulse and thrust vector of small attitude control jets

NASA Technical Reports Server (NTRS)

Woodruff, J. R.; Chisel, D. M.

1973-01-01

A test stand which accurately measures the impulse bit and thrust vector of reaction jet thrusters used in the attitude control system of space vehicles has been developed. It can be used to measure, in a vacuum or ambient environment, both impulse and thrust vector of reaction jet thrusters using hydrazine or inert gas propellants. The ballistic pendulum configuration was selected because of its accuracy, simplicity, and versatility. The pendulum is mounted on flexure pivots rotating about a vertical axis at the center of its mass. The test stand has the following measurement capabilities: impulse of 0.00004 to 4.4 N-sec (0.00001 to 1.0 lb-sec) with a pulse duration of 0.5 msec to 1 sec; static thrust of 0.22 to 22 N (0.05 to 5 lb) with a 5 percent resolution; and thrust angle alinement of 0.22 to 22 N (0.05 to 5 lb) thrusters with 0.01 deg accuracy.
Surface Instability of Liquid Propellant under Vertical Oscillatory Forcing

NASA Technical Reports Server (NTRS)

Yang, H. Q.; Peugeot, John

2011-01-01

Fluid motion in a fuel tank produced during thrust oscillations can circulate sub-cooled hydrogen near the liquid-vapor interface resulting in increased condensation and ullage pressure collapse. The first objective of this study is to validate the capabilities of a Computational Fluid Dynamics (CFD) tool, CFD-ACE+, in modeling the fundamental interface transition physics occurring at the propellant surface. The second objective is to use the tool to assess the effects of thrust oscillations on surface dynamics. Our technical approach is to first verify the CFD code against known theoretical solutions, and then validate against existing experiments for small scale tanks and a range of transition regimes. A 2D axisymmetric, multi-phase model of gases, liquids, and solids is used to verify that CFD-ACE+ is capable of modeling fluid-structure interaction and system resonance in a typical thrust oscillation environment. Then, the 3D mode is studied with an assumed oscillatory body force to simulate the thrust oscillating effect. The study showed that CFD modeling can capture all of the transition physics from solid body motion to standing surface wave and to droplet ejection from liquid-gas interface. Unlike the analytical solutions established during the 1960 s, CFD modeling is not limited to the small amplitude regime. It can extend solutions to the nonlinear regime to determine the amplitude of surface waves after the onset of instability. The present simulation also demonstrated consistent trends from numerical experiments through variation of physical properties from low viscous fluid to high viscous fluids, and through variation of geometry and input forcing functions. A comparison of surface wave patterns under various forcing frequencies and amplitudes showed good agreement with experimental observations. It is concluded that thrust oscillations can cause droplet formation at the interface, which results in increased surface area and enhanced heat transfer between the liquid and gas phases as the ejected droplets travel well into the warmer gas region.
Recommended Practices in Thrust Measurements

NASA Technical Reports Server (NTRS)

Polk, James E.; Pancotti, Anthony; Haag, Thomas; King, Scott; Walker, Mitchell; Blakely, Joseph; Ziemer, John

2013-01-01

Accurate, direct measurement of thrust or impulse is one of the most critical elements of electric thruster characterization, and one of the most difficult measurements to make. The American Institute of Aeronautics and Astronautics has started an initiative to develop standards for many important measurement processes in electric propulsion, including thrust measurements. This paper summarizes recommended practices for the design, calibration, and operation of pendulum thrust stands, which are widely recognized as the best approach for measuring micro N- to mN-level thrust and micro Ns-level impulse bits. The fundamentals of pendulum thrust stand operation are reviewed, along with its implementation in hanging pendulum, inverted pendulum, and torsional balance configurations. Methods of calibration and recommendations for calibration processes are presented. Sources of error are identified and methods for data processing and uncertainty analysis are discussed. This review is intended to be the first step toward a recommended practices document to help the community produce high quality thrust measurements.
A Performance Comparison of Xenon and Krypton Propellant on an SPT-100 Hall Thruster (Preprint)

DTIC Science & Technology

2011-08-10

plume data from electrostatic probes. This paper presents the results of performance measurements made using an inverted pendulum thrust stand. Krypton...inverted pendulum thrust stand. Krypton operating conditions were tested over a large range of operating powers from 800 W to 3.9 kW. Analysis of how...advantages for missions where high thrust at reduced specific impulse is advantageous, primarily for orbit raising missions. Bismuth’s main drawback is
Test Stand at the Rocket Engine Test Facility

NASA Image and Video Library

1973-02-21

The thrust stand in the Rocket Engine Test Facility at the National Aeronautics and Space Administration (NASA) Lewis Research Center in Cleveland, Ohio. The Rocket Engine Test Facility was constructed in the mid-1950s to expand upon the smaller test cells built a decade before at the Rocket Laboratory. The $2.5-million Rocket Engine Test Facility could test larger hydrogen-fluorine and hydrogen-oxygen rocket thrust chambers with thrust levels up to 20,000 pounds. Test Stand A, seen in this photograph, was designed to fire vertically mounted rocket engines downward. The exhaust passed through an exhaust gas scrubber and muffler before being vented into the atmosphere. Lewis researchers in the early 1970s used the Rocket Engine Test Facility to perform basic research that could be utilized by designers of the Space Shuttle Main Engines. A new electronic ignition system and timer were installed at the facility for these tests. Lewis researchers demonstrated the benefits of ceramic thermal coatings for the engine’s thrust chamber and determined the optimal composite material for the coatings. They compared the thermal-coated thrust chamber to traditional unlined high-temperature thrust chambers. There were more than 17,000 different configurations tested on this stand between 1973 and 1976. The Rocket Engine Test Facility was later designated a National Historic Landmark for its role in the development of liquid hydrogen as a propellant.
Solid Rocket Boosters Separation

NASA Technical Reports Server (NTRS)

1982-01-01

This view, taken by a motion picture tracking camera for the STS-3 mission, shows both left and right solid rocket boosters (SRB's) at the moment of separation from the external tank (ET). After impact to the ocean, they were retrieved and refurbished for reuse. The Shuttle's SRB's and solid rocket motors (SRM's) are the largest ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds. That is equivalent to 44 million horsepower, or the combined power of 400,000 subcompact cars.
Thrust Measurements of an Underexpanded Orifice in the Transitional Regime

NASA Astrophysics Data System (ADS)

Ketsdever, Andrew D.

2003-05-01

The popularity of micropropulsion system development has led to renewed interest in the determination of propulsive properties of orifice flows since micronozzle expansions may suffer high viscous losses at low pressure operation. The mass flow and relative thrust for an under expanded orifice is measured as a function of orifice stagnation pressure from 0.1 to 3.5 Torr. Nitrogen, argon, and helium propellant gases are passed through a 1.0 mm diameter orifice with a wall thickness of 0.015 mm . Near-free molecule, transitional and continuum flow regimes are studied. The relative thrust is determined by a novel thrust stand designed primarily for low operating pressure, micropropulsion systems. It is shown that the thrust indications obtained from the stand are a function of the facility background pressure, and corrections are made to determine the indicated thrust for a zero background pressure with nitrogen as propellant. Highly repeatable (within 1 %) indicated thrust measurements are obtained in the thrust range from 5 to 500 μN.
Analysis on the multi-dimensional spectrum of the thrust force for the linear motor feed drive system in machine tools

NASA Astrophysics Data System (ADS)

Yang, Xiaojun; Lu, Dun; Ma, Chengfang; Zhang, Jun; Zhao, Wanhua

2017-01-01

The motor thrust force has lots of harmonic components due to the nonlinearity of drive circuit and motor itself in the linear motor feed drive system. What is more, in the motion process, these thrust force harmonics may vary with the position, velocity, acceleration and load, which affects the displacement fluctuation of the feed drive system. Therefore, in this paper, on the basis of the thrust force spectrum obtained by the Maxwell equation and the electromagnetic energy method, the multi-dimensional variation of each thrust harmonic is analyzed under different motion parameters. Then the model of the servo system is established oriented to the dynamic precision. The influence of the variation of the thrust force spectrum on the displacement fluctuation is discussed. At last the experiments are carried out to verify the theoretical analysis above. It can be found that the thrust harmonics show multi-dimensional spectrum characteristics under different motion parameters and loads, which should be considered to choose the motion parameters and optimize the servo control parameters in the high-speed and high-precision machine tools equipped with the linear motor feed drive system.
A Performance and Plume Comparison of Xenon and Krypton Propellant on the SPT-100

DTIC Science & Technology

2012-07-02

HET (1.35 kW), performance measurements were made using an inverted pendulum thrust stand. The plume was also characterized by a Faraday probe and RPA...performance reduction for the case of the flight model SPT-100 HET (1.35 kW), per- formance measurements were made using an inverted pendulum thrust stand...where high thrust at reduced specific impulse is advantageous, such as orbit raising missions. Bismuth’s main drawback is that the metal must be
An analysis of cross-coupling of a multicomponent jet engine test stand using finite element modeling techniques

NASA Technical Reports Server (NTRS)

Schweikhard, W. G.; Singnoi, W. N.

1985-01-01

A two axis thrust measuring system was analyzed by using a finite a element computer program to determine the sensitivities of the thrust vectoring nozzle system to misalignment of the load cells and applied loads, and the stiffness of the structural members. Three models were evaluated: (1) the basic measuring element and its internal calibration load cells; (2) the basic measuring element and its external load calibration equipment; and (3) the basic measuring element, external calibration load frame and the altitude facility support structure. Alignment of calibration loads was the greatest source of error for multiaxis thrust measuring systems. Uniform increases or decreases in stiffness of the members, which might be caused by the selection of the materials, have little effect on the accuracy of the measurements. It is found that the POLO-FINITE program is a viable tool for designing and analyzing multiaxis thrust measurement systems. The response of the test stand to step inputs that might be encountered with thrust vectoring tests was determined. The dynamic analysis show a potential problem for measuring the dynamic response characteristics of thrust vectoring systems because of the inherently light damping of the test stand.
Thrust Stand Characterization of the NASA Evolutionary Xenon Thruster (NEXT)

NASA Technical Reports Server (NTRS)

Diamant, Kevin D.; Pollard, James E.; Crofton, Mark W.; Patterson, Michael J.; Soulas, George C.

2010-01-01

Direct thrust measurements have been made on the NASA Evolutionary Xenon Thruster (NEXT) ion engine using a standard pendulum style thrust stand constructed specifically for this application. Values have been obtained for the full 40-level throttle table, as well as for a few off-nominal operating conditions. Measurements differ from the nominal NASA throttle table 10 (TT10) values by 3.1 percent at most, while at 30 throttle levels (TLs) the difference is less than 2.0 percent. When measurements are compared to TT10 values that have been corrected using ion beam current density and charge state data obtained at The Aerospace Corporation, they differ by 1.2 percent at most, and by 1.0 percent or less at 37 TLs. Thrust correction factors calculated from direct thrust measurements and from The Aerospace Corporation s plume data agree to within measurement error for all but one TL. Thrust due to cold flow and "discharge only" operation has been measured, and analytical expressions are presented which accurately predict thrust based on thermal thrust generation mechanisms.
The kinematic determinants of anuran swimming performance: an inverse and forward dynamics approach.

PubMed

Richards, Christopher T

2008-10-01

The aims of this study were to explore the hydrodynamic mechanism of Xenopus laevis swimming and to describe how hind limb kinematics shift to control swimming performance. Kinematics of the joints, feet and body were obtained from high speed video of X. laevis frogs (N=4) during swimming over a range of speeds. A blade element approach was used to estimate thrust produced by both translational and rotational components of foot velocity. Peak thrust from the feet ranged from 0.09 to 0.69 N across speeds ranging from 0.28 to 1.2 m s(-1). Among 23 swimming strokes, net thrust impulse from rotational foot motion was significantly higher than net translational thrust impulse, ranging from 6.1 to 29.3 N ms, compared with a range of -7.0 to 4.1 N ms from foot translation. Additionally, X. laevis kinematics were used as a basis for a forward dynamic anuran swimming model. Input joint kinematics were modulated to independently vary the magnitudes of foot translational and rotational velocity. Simulations predicted that maximum swimming velocity (among all of the kinematics patterns tested) requires that maximal translational and maximal rotational foot velocity act in phase. However, consistent with experimental kinematics, translational and rotational motion contributed unequally to total thrust. The simulation powered purely by foot translation reached a lower peak stroke velocity than the pure rotational case (0.38 vs 0.54 m s(-1)). In all simulations, thrust from the foot was positive for the first half of the power stroke, but negative for the second half. Pure translational foot motion caused greater negative thrust (70% of peak positive thrust) compared with pure rotational simulation (35% peak positive thrust) suggesting that translational motion is propulsive only in the early stages of joint extension. Later in the power stroke, thrust produced by foot rotation overcomes negative thrust (due to translation). Hydrodynamic analysis from X. laevis as well as forward dynamics give insight into the differential roles of translational and rotational foot motion in the aquatic propulsion of anurans, providing a mechanistic link between joint kinematics and swimming performance.
Spatial measurement in rotating magnetic field plasma acceleration method by using two-dimensional scanning instrument and thrust stand

NASA Astrophysics Data System (ADS)

Furukawa, T.; Takizawa, K.; Yano, K.; Kuwahara, D.; Shinohara, S.

2018-04-01

A two-dimensional scanning probe instrument has been developed to survey spatial plasma characteristics in our electrodeless plasma acceleration schemes. In particular, diagnostics of plasma parameters, e.g., plasma density, temperature, velocity, and excited magnetic field, are essential for elucidating physical phenomena since we have been concentrating on next generation plasma propulsion methods, e.g., Rotating Magnetic Field plasma acceleration method, by characterizing the plasma performance. Moreover, in order to estimate the thrust performance in our experimental scheme, we have also mounted a thrust stand, which has a target type, on this movable instrument, and scanned the axial profile of the thrust performance in the presence of the external magnetic field generated by using permanent magnets, so as to investigate the plasma captured in a stand area, considering the divergent field lines in the downstream region of a generation antenna. In this paper, we will introduce the novel measurement instrument and describe how to measure these parameters.
TMS installation at A-1 Test Stand

NASA Image and Video Library

2010-03-03

A new thrust measurement system is lifted onto the A-1 Test Stand deck at NASA's John C. Stennis Space Center in preparation for its installation. The new system is a state-of-the-art upgrade for the testing structure, which is being prepared for testing of next-generation rocket engines. The system was fabricated by Thrust Measurement Systems in Illinois at a cost of about $3.5 million.
Detailed Design of a Pulsed Plasma Thrust Stand

NASA Astrophysics Data System (ADS)

Verbin, Andrew J.

This thesis gives a detailed design process for a pulsed type thruster. The thrust stand designed in this paper is for a Pulsed Plasma Thruster built by Sun Devil Satellite Laboratory, a student organization at Arizona State University. The thrust stand uses a torsional beam rotating to record displacement. This information, along with impulse-momentum theorem is applied to find the impulse bit of the thruster, which varies largely from other designs which focus on using the natural dynamics their fixtures. The target impulse to record on this fixture was estimated to be 275 muN-s of impulse. Through calibration and experimentation, the fixture is capable of recording an impulse of 332 muN-s +/- 14.81 muN-s, close to the target impulse. The error due to noise was characterized and evaluated to be under 5% which is deemed to be acceptable.

Computational Validation of a Two-Dimensional Semi-Empirical Model for Inductive Coupling in a Conical Pulsed Inductive Plasma Thruster

NASA Technical Reports Server (NTRS)

Hallock, Ashley K.; Polzin, Kurt A.

2011-01-01

A two-dimensional semi-empirical model of pulsed inductive thrust efficiency is developed to predict the effect of such a geometry on thrust efficiency. The model includes electromagnetic and gas-dynamic forces but excludes energy conversion from radial motion to axial motion, with the intention of characterizing thrust efficiency loss mechanisms that result from a conical versus a at inductive coil geometry. The range of conical pulsed inductive thruster geometries to which this model can be applied is explored with the use of finite element analysis. A semi-empirical relation for inductance as a function of current sheet radial and axial position is the limiting feature of the model, restricting the applicability as a function of half cone angle to a range from ten degrees to about 60 degrees. The model is nondimensionalized, yielding a set of dimensionless performance scaling parameters. Results of the model indicate that radial current sheet motion changes the axial dynamic impedance parameter at which thrust efficiency is maximized. This shift indicates that when radial current sheet motion is permitted in the model longer characteristic circuit timescales are more efficient, which can be attributed to a lower current sheet axial velocity as the plasma more rapidly decouples from the coil through radial motion. Thrust efficiency is shown to increase monotonically for decreasing values of the radial dynamic impedance parameter. This trend indicates that to maximize the radial decoupling timescale should be long compared to the characteristic circuit timescale.
Pulsed thrust measurements using electromagnetic calibration techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang Haibin; Shi Chenbo; Zhang Xin'ai

2011-03-15

A thrust stand for accurately measuring impulse bits, which ranged from 10-1000 {mu}N s using a noncontact electromagnetic calibration technique is described. In particular, a permanent magnet structure was designed to produce a uniform magnetic field, and a multiturn coil was made to produce a calibration force less than 10 mN. The electromagnetic calibration force for pulsed thrust measurements was linear to the coil current and changed less than 2.5% when the distance between the coil and magnet changed 6 mm. A pulsed plasma thruster was first tested on the thrust stand, and afterward five single impulse bits were measuredmore » to give a 310 {mu}N s average impulse bit. Uncertainty of the measured impulse bit was analyzed to evaluate the quality of the measurement and was found to be 10 {mu}N s with 95% credibility.« less
Schlieren Imaging of a Single-Ejector, Multi-Tube Pulsed Detonation Engine (Postprint)

DTIC Science & Technology

2009-01-01

studies have shown the potential of an ejector to almost double the thrust of a pulsed detonation engine ( PDE ) tube [1-3]. Axial misalignment of the... Detonation Research Facility in the Air Force Research Laboratory were used for this study. The PDE utilizes automotive valving to feed up to four... detonation tubes. The damped thrust stand was setup to measure PDE thrust alone for baseline tests or total thrust from ejector and PDE . This
Advanced Manufacturing Technologies (AMT): Additive Manufactured Hot Fire Planning and Testing in GRC Cell 32 Project

NASA Technical Reports Server (NTRS)

Fikes, John C.

2014-01-01

The objective of this project is to hot fire test an additively manufactured thrust chamber assembly TCA (injector and thrust chamber). GRC will install the additively manufactured Inconel 625 injector, two additively manufactured (SLM) water cooled Cu-Cr thrust chamber barrels and one additively manufactured (SLM) water cooled Cu-Cr thrust chamber nozzle on the test stand in Cell 32 and perform hot fire testing of the integrated TCA.
Identification of human-generated forces on wheelchairs during total-body extensor thrusts.

PubMed

Hong, Seong-Wook; Patrangenaru, Vlad; Singhose, William; Sprigle, Stephen

2006-10-01

Involuntary extensor thrust experienced by wheelchair users with neurological disorders may cause injuries via impact with the wheelchair, lead to the occupant sliding out of the seat, and also damage the wheelchair. The concept of a dynamic seat, which allows movement of a seat with respect to the wheelchair frame, has been suggested as a potential solution to provide greater freedom and safety. Knowledge of the human-generated motion and forces during unconstrained extensor thrust events is of great importance in developing more comfortable and effective dynamic seats. The objective of this study was to develop a method to identify human-generated motions and forces during extensor thrust events. This information can be used to design the triggering system for a dynamic seat. An experimental system was developed to automatically track the motions of the wheelchair user using a video camera and also measure the forces at the footrest. An inverse dynamic approach was employed along with a three-link human body model and the experimental data to predict the human-generated forces. Two kinds of experiments were performed: the first experiment validated the proposed model and the second experiment showed the effects of the extensor thrust speed, the footrest angle, and the seatback angle. The proposed method was tested using a sensitivity analysis, from which a performance index was deduced to help indicate the robust region of the force identification. A system to determine human-generated motions and forces during unconstrained extensor thrusts was developed. Through experiments and simulations, the effectiveness and reliability of the developed system was established.
Thrust Generation with Low-Power Continuous-Wave Laser and Aluminum Foil Interaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horisawa, Hideyuki; Sumida, Sota; Funaki, Ikkoh

2010-05-06

The micro-newton thrust generation was observed through low-power continuous-wave laser and aluminum foil interaction without any remarkable ablation of the target surface. To evaluate the thrust characteristics, a torsion-balance thrust stand capable for the measurement of the thrust level down to micro-Newton ranges was developed. In the case of an aluminum foil target with 12.5 micrometer thickness, the maximum thrust level was 15 micro-newtons when the laser power was 20 W, or about 0.75 N/MW. It was also found that the laser intensity, or laser power per unit area, irradiated on the target was significantly important on the control ofmore » the thrust even under the low-intensity level.« less
Advanced Space Transportation Program (ASTP)

NASA Image and Video Library

1997-08-07

This double exposure depicts Marshall Space Flight Center's (MSFC) Test Stand 116 hosting a 60K Bantam Fastrac thrust chamber assembly test. The lower right exposure shows the engine firing in the test stand while the center exposure reveals workers monitoring the test in the interior block house of the test facility. The thrust chamber assembly is only part of the Fastrac engine project to build a low-cost engine for the X-34, an alternate light-weight unmarned launch vehicle. Both the nozzle and the engine for Fastrac are being manufactured at MSFC.
Design and characterization of a nano-Newton resolution thrust stand

NASA Astrophysics Data System (ADS)

Soni, J.; Roy, S.

2013-09-01

The paper describes the design, calibration, and characterization of a thrust stand capable of nano-Newton resolution. A low uncertainty calibration method is proposed and demonstrated. A passive eddy current based damper, which is non-contact and vacuum compatible, is employed. Signal analysis techniques are used to perform noise characterization, and potential sources are identified. Calibrated system noise floor suggests thrust measurement resolution of the order of 10 nN is feasible under laboratory conditions. Force measurement from this balance for a standard macroscale dielectric barrier discharge (DBD) plasma actuator is benchmarked with a commercial precision balance of 9.8 μN resolution and is found to be in good agreement. Published results of a microscale DBD plasma actuator force measurement and low pressure characterization of conventional plasma actuators are presented for completeness.
Explicit Low-Thrust Guidance for Reference Orbit Targeting

NASA Technical Reports Server (NTRS)

Lam, Try; Udwadia, Firdaus E.

2013-01-01

The problem of a low-thrust spacecraft controlled to a reference orbit is addressed in this paper. A simple and explicit low-thrust guidance scheme with constrained thrust magnitude is developed by combining the fundamental equations of motion for constrained systems from analytical dynamics with a Lyapunov-based method. Examples are given for a spacecraft controlled to a reference trajectory in the circular restricted three body problem.
The Air Force Phillips Laboratory multimegawatt quasi-steady MPD thruster facility

NASA Astrophysics Data System (ADS)

Castillo, Salvador; Tilley, Dennis L.

1992-07-01

The operational multimegawatt quasi-steady MPD thruster facility is described in terms of its general design emphasizing the impulse thrust stand and diagnostics capabilities. The vacuum, propellant, and electrical systems are discussed with schematic diagrams of the respective component configurations and explanations of the needs of MPD thruster testing. The impulse thrust stand comprises an accelerometer/pendulum-impulse stand which can be used to correlate thruster impulse with accelerometer readings and thereby reduce measurement uncertainties. The diagnostics of the terminal characteristics of the thruster operation are complemented by diagnostics platforms that study plasma properties in the plume and the thruster. Preliminary tests indicate that the MPD thruster facility is prepared for detailed investigations of MPD thruster performance and plume diagnostics.
Propulsive performance of biologically inspired flapping foils at high Reynolds numbers.

PubMed

Techet, Alexandra H

2008-01-01

Propulsion and maneuvering underwater by flapping foil motion, optimized through years of evolution, is ubiquitous in nature, yet marine propulsors inspired by examples of highly maneuverable marine life or aquatic birds are not widely implemented in engineering. Performance data from flapping foils, moving in a rolling and pitching motion, are presented at high Reynolds numbers, Re=Uc/nu, or O(10(4)), where U is the relative inflow velocity, c is the chord length of the foil, and nu is the kinematic viscosity of the fluid, from water tunnel experiments using a foil actuator module designed after an aquatic penguin or turtle fin. The average thrust coefficients and efficiency measurements are recorded over a range of kinematic flapping amplitudes and frequencies. Results reveal a maximum thrust coefficient of 2.09, and for low values of angle of attack the thrust generally increases with Strouhal number, without much penalty to efficiency. Strouhal number is defined as St=2h(0)f/U, where f is the frequency of flapping, and 2h(0) is the peak-to-peak amplitude of flapping. The thrust and efficiency contour plots also present a useful performance trend where, at low angles of attack, high thrust and efficiency can be gained at sufficiently high Strouhal numbers. Understanding the motion of aquatic penguins and turtle wings and emulating these motions mechanically can yield insight into the hydrodynamics of how these animals swim and also improve performance of biologically inspired propulsive devices.
Force-motion phase relations and aerodynamic performance of a plunging plate

NASA Astrophysics Data System (ADS)

Son, Onur; Cetiner, Oksan

2018-02-01

Due to the unsteady motion of a plunging plate, forces acting on the body experience a phase difference with respect to the motion. These phase relations are investigated experimentally for a harmonically plunging plate within an amplitude range of 0.05≤ {a/c}≤ 0.6, reduced frequency range of 0.78<{k}<7.06, and at a constant Reynolds number of 10,000. Both streamwise and cross-stream force components are found to have a phase lag following the motion; however, their variations are different. The phase lag of the force on the cross-stream direction increases as the amplitude increases. Drag-thrust transition has an influence on the streamwise force phase lags, which starts to increase when the thrust starts to be produced. Particle image velocimetry measurements are also performed to reveal the relations between vortex structures and force measurements. Leading edge vortex shedding characteristics are observed to be changing from drag occurring cases to thrust producing cases in parallel with the increment in phase lags.
Design and development of a biomimetic device for micro air vehicles

NASA Astrophysics Data System (ADS)

Bohorquez, Felipe; Pines, Darryll J.

2002-07-01

This paper presents the design and development of a pitching and plunging (flapping) mechanism for small-scale flight. In order to harness the unsteady lift mechanisms, used by most insects, a biologically inspired flapping/pitching device in conjunction with a rotary wing concept was developed and built. This mechanism attempts to replicate some of the aerodynamic phenomena that enhance the performance of small fliers, replacing the periodic translational motion with a unidirectional circular motion while actively flapping and pitching the rotor blades. In order to find the appropriate combination of phase, amplitude, frequency and rotational speed that leads to enhancement in lift, the device requires uncoupled independent pitch and flap actuation systems to permit the complete mapping of the parameter space. In the device under consideration the phase shift between the flapping and the pitching oscillations can be adjusted from 0 to 360 degrees over a wide range of rotational speeds. Maximum flapping and pitching amplitudes of +/- 23 degree(s) and +/- 20 degree(s) respectively can be attained. Linear displacements of two coaxial shafts are translated into the flapping and pitching motion of the rotor blades. The mechanism was designed to minimize the actuation stroke so that smart materials and conventional actuators such as motors and cams could be used. Kinematic analysis as well as experimental tests were performed. Using a customized test stand thrust and torque produced by the rotor were measured at different angles of attack, in steady-state and under periodical pitching actuation. The results showed that hover efficiency was considerably increased for a range of thrust coefficients. The device was developed based on the University of Maryland's rotary wing Micro Air vehicle (MAV) the MICOR (MIcro COaxial Rotorcraft), an electrically driven 100 g coaxial helicopter. It is anticipated that active flapping and/or pitching could be implemented in the prototype to improve its aerodynamic performance. The present paper will discuss the design and development process of a rotating/pitching/flapping mechanism for MAVs. Test results indicate that unsteady pitching motion can be used to include the aerodynamic effect of delayed stall. Performance measurements confirm that unsteady pitching motion improves efficiency in hover.
Valemount strain zone: A dextral oblique-slip thrust system linking the Rocky Mountain and Omineca belts of the southeastern Canadian Cordillera

NASA Astrophysics Data System (ADS)

McDonough, Michael R.; Simony, Philip S.

1989-03-01

The Valemount strain zone (VSZ), a narrow zone of high orogen-parallel (OP) strain in pebble conglomerate of the Late Proterozoic Miette Group, is the footwall expression of a thrust fault on the western edge of the Rocky Mountain belt, marking the eastern limit of a wide zone of OP fabrics distributed through the Omineca crystalline and western Rocky Mountain belts of the southeastern Canadian Cordillera. Kinematic indicators from the VSZ and the adjacent Bear Foot thrust zone show that both thrust and dextral displacement are associated with folding and thrust motion in the Rocky Mountains, thereby linking the southern Rocky Mountain belt to the Omineca belt by an oblique-slip thrust regime that is tectonically unrelated to the Southern Rocky Mountain Trench. Transverse shortening of thrust sheets and subsequent distribution of OP shear are invoked to explain the parallelism of stretching lineations and fold axes. Strain and kinematic data and the thrust-belt geometry of the VSZ suggest that OP lineations are a product of a large amount of transverse shortening during slightly oblique A-type subduction. Thus, OP lineations are not representative of relative plate motions between North America and accreted terranes, but probably are a function of footwall buttressing of thrust sheets, a mechanism that may be widely applicable to the internal zones of collisional orogens.
Performance of active and passive control of an airfoil using CPFD

NASA Astrophysics Data System (ADS)

Asselin, Daniel; Young, Jay; Williamson, C. H. K.

2016-11-01

Birds and fish employ flapping motions of their wings and fins in order to produce thrust and maneuver in flight and underwater. There is considerable interest in designing aerial and submersible systems that mimic these motions for the purposes of surveillance, environmental monitoring, and search and rescue, among other applications. Flapping motions are typically composed of combined pitch and heave and can provide good thrust and efficiency (Read, et al. 2003). In this study, we examine the performance of an airfoil actuated only in the heave direction. Using a cyber-physical fluid dynamics system (Mackowski & Williamson 2011, 2015, 2016), we simulate the presence of a torsion spring to enable the airfoil to undergo a passively controlled pitching motion. The addition of passive pitching combined with active heaving ("Active-Passive" or AP) provides significantly improved thrust and efficiency compared with heaving alone. In many cases, values of thrust and efficiency are comparable to or better than those obtained with two actively controlled degrees of freedom ("Active-Active" or AA). By using carefully-designed passive dynamics in the pitch direction, we can eliminate one of the two actuators, saving cost, complexity, and weight, while maintaining or improving performance. This work was supported by the Air Force Office of Scientific Research Grant No. FA9550-15-1-0243, monitored by Dr. Douglas Smith.
Associations of Varus Thrust and Alignment with Pain in Knee Osteoarthritis

PubMed Central

Lo, Grace H.; Harvey, William F.; McAlindon, Timothy E.

2012-01-01

Objective To compare associations of varus thrust and varus static alignment with pain in those with knee osteoarthritis (OA). Method This was a cross-sectional study of participants from a randomized controlled trial of vitamin D for knee OA. Participants were video recorded walking and scored for presence of varus thrust. Standard PA knee X-rays were measured for static alignment. Pain questions from the Western Ontario McMasters Osteoarthritis (WOMAC) questionnaire assessed symptoms. We calculated means for total WOMAC pain by varus thrust and varus alignment (i.e. corrected anatomic alignment < 178°). We performed ordinal logistic regressions; outcomes: individual WOMAC pain questions; predictors: varus thrust and varus alignment. Results There were 82 participants, mean age 65.1 (±8.5), mean body mass index 30.2 (±5.4), and 60% female. Total WOMAC pain was 6.3 versus 3.9, p = 0.007 in those with versus without definite varus thrust. For varus alignment, total WOMAC pain was 5.2 versus 4.2, p = 0.30. Odds ratios for pain with walking and standing were 5.5 (95%CI 2.0 – 15.1) and 6.0 (95%CI 2.2 – 16.2) in those with versus without definite varus thrust. There were no significant associations between varus alignment and individual WOMAC pain questions. Sensitivity analyses suggested a more stringent definition of varus might have been associated with walking and standing pain. Conclusion In those with knee OA, varus thrust and possibly varus static alignment, were associated with pain, specifically during weight-bearing activities. Treatment of varus thrust (e.g. via bracing or gait modification) may lead to improvement of symptoms. PMID:22307813
Neurobiology of Caenorhabditis elegans Locomotion: Where Do We Stand?

PubMed Central

Gjorgjieva, Julijana; Biron, David; Haspel, Gal

2014-01-01

Animals use a nervous system for locomotion in some stage of their life cycle. The nematode Caenorhabditis elegans, a major animal model for almost all fields of experimental biology, has long been used for detailed studies of genetic and physiological locomotion mechanisms. Of its 959 somatic cells, 302 are neurons that are identifiable by lineage, location, morphology, and neurochemistry in every adult hermaphrodite. Of those, 75 motoneurons innervate body wall muscles that provide the thrust during locomotion. In this Overview, we concentrate on the generation of either forward- or backward-directed motion during crawling and swimming. We describe locomotion behavior, the parts constituting the locomotion system, and the relevant neuronal connectivity. Because it is not yet fully understood how these components combine to generate locomotion, we discuss competing hypotheses and models. PMID:26955070
Wall interaction effects for a full-scale helicopter rotor in the NASA Ames 80- by 120-foot wind tunnel

NASA Technical Reports Server (NTRS)

Shinoda, Patrick M.

1994-01-01

A full-scale helicopter rotor test was conducted in the NASA Ames 80- by 120-Foot Wind Tunnel with a four-bladed S-76 rotor system. This wind tunnel test generated a unique and extensive data base covering a wide range of rotor shaft angles-of-attack and rotor thrust conditions from 0 to 100 knots. Three configurations were tested: (1) empty tunnel; (2) test stand body (fuselage) and support system; and (3) fuselage and support system with rotor installed. Empty tunnel wall pressure data are evaluated as a function of tunnel speed to understand the baseline characteristics. Aerodynamic interaction effects between the fuselage and the walls of the tunnel are investigated by comparing wall, ceiling, and floor pressures for various tunnel velocities and fuselage angles-of-attack. Aerodynamic interaction effects between the rotor and the walls of the tunnel are also investigated by comparing wall, ceiling, and floor pressures for various rotor shaft angles, rotor thrust conditions, and tunnel velocities. Empty tunnel wall pressure data show good repeatability and are not affected by tunnel speed. In addition, the tunnel wall pressure profiles are not affected by the presence of the fuselage apart from a pressure shift. Results do not indicate that the tunnel wall pressure profiles are affected by the presence of the rotor. Significant changes in the wall, ceiling, and floor pressure profiles occur with changing tunnel speeds for constant rotor thrust and shaft angle conditions. Significant changes were also observed when varying rotor thrust or rotor shaft angle-of-attack. Other results indicate that dynamic rotor loads and blade motion are influenced by the presence of the tunnel walls at very low tunnel velocity and, together with the wall pressure data, provide a good indication of flow breakdown.
Performance of a 100 kW class applied field MPD thruster

NASA Technical Reports Server (NTRS)

Mantenieks, Maris A.; Sovey, James S.; Myers, Roger M.; Haag, Thomas W.; Raitano, Paul; Parkes, James E.

1989-01-01

Performance of a 100 kW, applied field magnetoplasmadynamic (MPD) thruster was evaluated and sensitivities of discharge characteristics to arc current, mass flow rate, and applied magnetic field were investigated. Thermal efficiencies as high as 60 percent, thrust efficiencies up to 21 percent, and specific impulses of up to 1150 s were attained with argon propellant. Thrust levels up to 2.5 N were directly measured with an inverted pendulum thrust stand at discharge input powers up to 57 kW. It was observed that thrust increased monotonically with the product of arc current and magnet current.
Analytical investigations in aircraft and spacecraft trajectory optimization and optimal guidance

NASA Technical Reports Server (NTRS)

Markopoulos, Nikos; Calise, Anthony J.

1995-01-01

A collection of analytical studies is presented related to unconstrained and constrained aircraft (a/c) energy-state modeling and to spacecraft (s/c) motion under continuous thrust. With regard to a/c unconstrained energy-state modeling, the physical origin of the singular perturbation parameter that accounts for the observed 2-time-scale behavior of a/c during energy climbs is identified and explained. With regard to the constrained energy-state modeling, optimal control problems are studied involving active state-variable inequality constraints. Departing from the practical deficiencies of the control programs for such problems that result from the traditional formulations, a complete reformulation is proposed for these problems which, in contrast to the old formulation, will presumably lead to practically useful controllers that can track an inequality constraint boundary asymptotically, and even in the presence of 2-sided perturbations about it. Finally, with regard to s/c motion under continuous thrust, a thrust program is proposed for which the equations of 2-dimensional motion of a space vehicle in orbit, viewed as a point mass, afford an exact analytic solution. The thrust program arises under the assumption of tangential thrust from the costate system corresponding to minimum-fuel, power-limited, coplanar transfers between two arbitrary conics. The thrust program can be used not only with power-limited propulsion systems, but also with any propulsion system capable of generating continuous thrust of controllable magnitude, and, for propulsion types and classes of transfers for which it is sufficiently optimal the results of this report suggest a method of maneuvering during planetocentric or heliocentric orbital operations, requiring a minimum amount of computation; thus uniquely suitable for real-time feedback guidance implementations.

Flight trajectories with maximum tangential thrust in a central Newtonian field

NASA Astrophysics Data System (ADS)

Azizov, A. G.; Korshunova, N. A.

1983-07-01

The paper examines the two-dimensional problem of determining the optimal trajectories of a point moving with a limited per-second mass consumption in a central Newtonian field. It is shown that one of the cases in which the variational equations in the Meier formulation can be integrated in quadratures is motion with maximum tangential thrust. Trajectories corresponding to this motion are determined. By way of application, attention is given to the problem of determining the thrust which assures maximum kinetic energy for the point at the moment t = t1, corresponding to the mass consumption M0 - M1, where M0 and M1 are, respectively, the initial and final mass.
Thrust Production and Wake Structure of a Batoid-Inspired Oscillating Fin

NASA Astrophysics Data System (ADS)

Clark, Richard

2005-11-01

Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a traveling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of Froude efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated.
Thrust production and wake structure of a batoid-inspired oscillating fin

NASA Astrophysics Data System (ADS)

Clark, R. P.; Smits, A. J.

2006-09-01

Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated.
Performance of Low-Power Pulsed Arcjets

NASA Technical Reports Server (NTRS)

Burton, Rodney L.

1995-01-01

The Electric Propulsion Laboratory at UIUC has in place all the capability and diagnostics required for performance testing of low power pulsed and DC arcjets. The UIUC thrust stand is operating with excellent accuracy and sensitivity at very low thrust levels. An important aspect of the experimental setup is the use of a PID controller to maintain a constant thruster position, which reduces hysterisis effects. Electrical noise from the arcjet induces some noise into the thrust signal, but this does not affect the measurement.
Saturn Apollo Program

NASA Image and Video Library

1964-10-01

Test firing of the Saturn I S-I Stage (S-1-10) at the Marshall Space Flight Center. This test stand was originally constructed in 1951 and sometimes called the Redstone or T tower. In l961, the test stand was modified to permit static firing of the S-I/S-IB stages, which produced a total thrust of 1,600,000 pounds. The name of the stand was then changed to the S-IB Static Test Stand.
Low-thrust solar electric propulsion navigation simulation program

NASA Technical Reports Server (NTRS)

Hagar, H. J.; Eller, T. J.

1973-01-01

An interplanetary low-thrust, solar electric propulsion mission simulation program suitable for navigation studies is presented. The mathematical models for trajectory simulation, error compensation, and tracking motion are described. The languages, input-output procedures, and subroutines are included.
Complex double-mass dynamic model of rotor on thrust foil gas dynamic bearings

NASA Astrophysics Data System (ADS)

Sytin, A.; Babin, A.; Vasin, S.

2017-08-01

The present paper considers simulation of a rotor’s dynamics behaviour on thrust foil gas dynamic bearings based on simultaneous solution of gas dynamics differential equations, equations of theory of elasticity, motion equations and some additional equations. A double-mass dynamic system was considered during the rotor’s motion simulation which allows not only evaluation of rotor’s dynamic behaviour, but also to evaluate the influence of operational and load parameters on the dynamics of the rotor-bearing system.
Thrust production and wake structure of a batoid-inspired oscillating fin

PubMed Central

CLARK, R. P.; SMITS, A. J.

2009-01-01

Experiments are reported on the hydrodynamic performance of a flexible fin. The fin replicates some features of the pectoral fin of a batoid fish (such as a ray or skate) in that it is actuated in a travelling wave motion, with the amplitude of the motion increasing linearly along the span from root to tip. Thrust is found to increase with non-dimensional frequency, and an optimal oscillatory gait is identified. Power consumption measurements lead to the computation of propulsive efficiency, and an optimal efficiency condition is evaluated. Wake visualizations are presented, and a vortex model of the wake near zero net thrust is suggested. Strouhal number effects on the wake topology are also illustrated. PMID:19746188
Associations of varus thrust and alignment with pain in knee osteoarthritis.

PubMed

Lo, Grace H; Harvey, William F; McAlindon, Timothy E

2012-07-01

To investigate associations of varus thrust and varus static alignment with pain in patients with knee osteoarthritis (OA). This was a cross-sectional study of participants from a randomized controlled trial of vitamin D treatment for knee OA. Participants were video recorded while walking and scored for presence of varus thrust. Static alignment was measured on standard posteroanterior knee radiographs. Pain questions from the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) questionnaire were used to assess symptoms. We calculated means for total WOMAC pain in relation to varus thrust and static varus alignment (i.e., corrected anatomic alignment<178 degrees). Ordinal logistic regressions were performed, with responses on individual WOMAC pain questions as the outcomes and varus thrust and varus alignment as the predictors. There were 82 participants, 60% of whom were female. The mean±SD age was 65.1±8.5 years, and the mean±SD body mass index was 30.2±5.4 kg/m2. The mean total WOMAC pain score was 6.3 versus 3.9, respectively, in those with versus without definite varus thrust (P=0.007) and 5.0 versus 4.2 in those with versus without varus alignment (P=0.36). Odds ratios for pain with walking and standing were 4.7 (95% confidence interval 1.8-11.9) and 5.5 (95% confidence interval 2.2-14.2), respectively, in those with and those without definite varus thrust. There were no significant associations between varus alignment and responses to individual WOMAC pain questions. Sensitivity analyses suggested that varus classified using a more stringent definition might have been associated with pain on walking and standing. In patients with knee OA, varus thrust, and possibly varus static alignment, were associated with pain, specifically during weight-bearing activities. Treatment of varus thrust (e.g., via bracing or gait modification) may lead to improvement of symptoms. Copyright © 2012 by the American College of Rheumatology.
n/a

NASA Image and Video Library

1961-01-01

The static firing of a Saturn F-1 engine at the Marshall Space Flight Center's Static Test Stand. The F-1 engine is a single-start, 1,5000,000 Lb fixed-thrust, bipropellant rocket system. The engine uses liquid oxygen as the oxidizer and RP-1 (kerosene) as fuel. The five-engine cluster used on the first stage of the Saturn V produces 7,500,000 lbs of thrust.
To flap or not to flap: continued discussion with particle image velocimetry of the near wake

NASA Astrophysics Data System (ADS)

Martin, Nathan; Roh, Chris; Idrees, Suhail; Gharib, Morteza

2017-11-01

We continue the discussion of which underwater propulsion mechanism is more effective: flapping used by fish or periodic contractions used by jellyfish. The two propulsion mechanisms are simplified into flapping and clapping plate motions, respectively, to allow for a direct comparison. A device is designed to operate in either mode of propulsion between Reynolds numbers 1,880 and 11,260, based on the average tip velocity and the span of the plate. The stroke angle, stroke time, flexibility, and duty cycle are varied to determine their impact on the generated thrust and the required torque. Overall, the clapping mode tends to require significantly more power to generate a similar thrust compared to that from the flapping mode. The performance of the clapping mode is increased by modifying the duty cycle such that the closing motion is faster than the opening motion causing a greater thrust and a similar efficiency to that from the flapping mode. Interestingly, when using rigid plates, the average thrust generated per cycle is similar between the two modes when the overall kinematics are equivalent. Investigation of the near wake of both modes through digital particle image velocimetry provides insight into the cause of this similar thrust. This work was supported by the Charyk Bio-inspired Laboratory at the California Institute of Technology, the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469, and the Summer Undergraduate Research Fellowships program.
Around Marshall

NASA Image and Video Library

1993-09-01

Marshall Space Flight Center's F-1 Engine Test Stand is shown in this picture. Constructed in 1963, the test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. The foundation of the stand is keyed into the bedrock approximately 40 feet below grade.
Aerodynamics of a Flapping Airfoil with a Flexible Tail

NASA Astrophysics Data System (ADS)

Lai, Alan Kai San

This dissertation presents computational solutions to an airfoil in a oscillatory heaving motion with a aeroelastically flexible tail attachment. An unsteady potential flow solver is coupled to a structural solver to obtain the aeroelastic flow solution over an inviscid fluid to investigate the propulsive performance of such a configuration. The simulation is then extended to a two-dimensional viscous solver by coupling NASA's CFL3D solver to the structural solver to study how the flow is altered by the presence of viscosity. Finally, additional simulations are done in three dimensions over wings with varying aspect ratio to study the three-dimensional effects on the propulsive performance of an airfoil with an aeroelastic tail. The computation reveals that the addition of the aeroelastic trailing edge improved the thrust generated by a heaving airfoil significantly. As the frequency of the heaving motion increases, the thrust generated by the airfoil with the tail increases exponentially. In an inviscid fluid, the increase in thrust is insufficient to overcome the increase in power required to maintain the motion and as a result the overall propulsive efficiency is reduced. When the airfoil is heaving in a viscous fluid, the presence of a suction boundary layer and the appearance of leading edge vortex increase the thrust generated to such an extent that the propulsive efficiency is increased by about 3% when compared to the same airfoil with a rigid tail. The three-dimensional computations shows that the presence of the tip vorticies suppress some of the increase in thrust observed in the two-dimensional viscous computations for short span wings. For large span wings, the overall thrust enhancing capabilities of the aeroelastic tail is preserved.
Performance of a Rotary Wing Air Brake in Supersonic Flow

DTIC Science & Technology

1947-05-18

a pneumatic thrust measuring system (3) Strobotac and Audio Signal Generator for RPM measurements, (4) motion picture cameras and miscellaneous...produced by the head to keep the brake engaged. The " pneumatic thrust measuring system1* utilised the bellows described above to oppose the drag force...a brake , to prevent its rotation when desired. To release the brake it was necessary to inflate the internal thrust bellows, thereby disengaging
A review of some exact solutions to the planar equations of motion of a thrusting spacecraft

NASA Technical Reports Server (NTRS)

Petropoulos, A. E.; Sims, J. A.

2002-01-01

With the complexities in computing optimal low thrust trajectories, easily-computed, good sub-optimal trajectories provide both a practical alternative for mission designers and a starting point for optimisation. The present paper collects in one place for easy reference and comparison several exact solutions that have been obtained in the literature over the last few decades: the logarithmic spiral, Pinkham's variant thereof, Forbes spiral, the exponential sinusoid, the case of constant radial thrust, Markopoulos's Keplerian thrust arcs, Lawden's spiral, and the analogous Bishop and Azimov spiral.
Operational evaluation of a proppeller test stand in the quiet flow facility at Langley Research Center

NASA Technical Reports Server (NTRS)

Block, P. J. W.

1982-01-01

Operational proof tests of a propeller test stand (PTS) in a quiet flow facility (QFF) are presented. The PTS is an experimental test bed for acoustic propeller research in the quiet flow environment of the QFF. These proof tests validate thrust and torque predictions, examine the repeatability of measurements on the PTS, and determine the effect of applying artificial roughness to the propeller blades. Since a thrusting propeller causes an open jet to contract, the potential flow core was surveyed to examine the magnitude of the contraction. These measurements are compared with predicted values. The predictions are used to determine operational limitations for testing a given propeller design in the QFF.
Modal Analysis with the Mobile Modal Testing Unit

NASA Technical Reports Server (NTRS)

Wilder, Andrew J.

2013-01-01

Recently, National Aeronautics and Space Administration's (NASA's) White Sands Test Facility (WSTF) has tested rocket engines with high pulse frequencies. This has resulted in the use of some of WSTF's existing thrust stands, which were designed for static loading, in tests with large dynamic forces. In order to ensure that the thrust stands can withstand the dynamic loading of high pulse frequency engines while still accurately reporting the test data, their vibrational modes must be characterized. If it is found that they have vibrational modes with frequencies near the pulsing frequency of the test, then they must be modified to withstand the dynamic forces from the pulsing rocket engines. To make this determination the Mobile Modal Testing Unit (MMTU), a system capable of determining the resonant frequencies and mode shapes of a structure, was used on the test stands at WSTF. Once the resonant frequency has been determined for a test stand, it can be compared to the pulse frequency of a test engine to determine whether or not that stand can avoid resonance and reliably test that engine. After analysis of test stand 406 at White Sands Test Facility, it was determined that natural frequencies for the structure are located around 75, 125, and 240 Hz, and thus should be avoided during testing.
Short-term effects of kinesio taping versus cervical thrust manipulation in patients with mechanical neck pain: a randomized clinical trial.

PubMed

Saavedra-Hernández, Manuel; Castro-Sánchez, Adelaida M; Arroyo-Morales, Manuel; Cleland, Joshua A; Lara-Palomo, Inmaculada C; Fernández-de-Las-Peñas, César

2012-08-01

Randomized clinical trial. To compare the effectiveness of cervical spine thrust manipulation to that of Kinesio Taping applied to the neck in individuals with mechanical neck pain, using self-reported pain and disability and cervical range of motion as measures. The effectiveness of cervical manipulation has received considerable attention in the literature. However, because some patients cannot tolerate cervical thrust manipulation, alternative therapeutic options should be investigated. Eighty patients (36 women) were randomly assigned to 1 of 2 groups: the manipulation group, which received 2 cervical thrust manipulations, and the tape group, which received Kinesio Taping applied to the neck. Neck pain (11-point numeric pain rating scale), disability (Neck Disability Index), and cervical-range-of-motion data were collected at baseline and 1 week after the intervention by an assessor blinded to the treatment allocation of the patients. Mixed-model analyses of variance were used to examine the effects of the treatment on each outcome variable, with group as the between-subjects variable and time as the within-subjects variable. The primary analysis was the group-by-time interaction. No significant group-by-time interactions were found for pain (F = 1.892, P = .447) or disability (F = 0.115, P = .736). The group-by-time interaction was statistically significant for right (F = 7.317, P = .008) and left (F = 9.525, P = .003) cervical rotation range of motion, with the patients who received the cervical thrust manipulation having experienced greater improvement in cervical rotation than those treated with Kinesio Tape (P<.01). No significant group-by-time interactions were found for cervical spine range of motion for flexion (F = 0.944, P = .334), extension (F = 0.122, P = .728), and right (F = 0.220, P = .650) and left (F = 0.389, P = .535) lateral flexion. Patients with mechanical neck pain who received cervical thrust manipulation or Kinesio Taping exhibited similar reductions in neck pain intensity and disability and similar changes in active cervical range of motion, except for rotation. Changes in neck pain surpassed the minimal clinically important difference, whereas changes in disability did not. Changes in cervical range of motion were small and not clinically meaningful. Because we did not include a control or placebo group in this study, we cannot rule out a placebo effect or natural changes over time as potential reasons for the improvements measured in both groups. Therapy, level 1b.
Experimental Determination of Exhaust Gas Thrust, Special Report

NASA Technical Reports Server (NTRS)

Pinkel, Benjamin; Voss, Fred

1940-01-01

This investigation presents the results of tests made on a radial engine to determine the thrust that can be obtained from the exhaust gas when discharged from separate stacks and when discharged from the collector ring with various discharge nozzles. The engine was provided with a propeller to absorb the power and was mounted on a test stand equipped with scales for measuring the thrust and engine torque. The results indicate that at full open throttle at sea level, for the engine tested, a gain in thrust horsepower of 18 percent using separate stacks, and 9.5 percent using a collector ring and discharge nozzle, can be expected at an air speed of 550 miles per hour.
The effect of talocrural joint manipulation on range of motion at the ankle.

PubMed

Fryer, Gary A; Mudge, Jacob M; McLaughlin, Patrick A

2002-01-01

To determine whether a single high-velocity, low-amplitude thrust manipulation to the talocrural joint altered ankle range of motion. A randomized, controlled and blinded study. Asymptomatic male and female volunteers (N = 41). Subjects were randomly assigned into either an experimental group (n = 20) or a control group (n = 21). Both ankles of subjects in the experimental group were manipulated by using a single high-velocity, low-amplitude thrust to the talocrural joint. Pretest and posttest measurements of passive dorsiflexion range of motion were taken. No significant changes in dorsiflexion range of motion were detected between manipulated ankles and those of control subjects. A significantly greater pretest dorsiflexion range of motion existed in those ankles in which manipulation produced an audible cavitation. Manipulation of the ankle does not increase dorsiflexion range of motion in asymptomatic subjects. Ankles that displayed a greater pretest range of dorsiflexion were more likely to cavitate, raising the possibility that ligament laxity may be associated with the tendency for ankles to cavitate.

14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the... this subpart must be run with the reverser installed. In complying with this section, the power control... regimes of control operations are incorporated necessitating scheduling of the power-control lever motion...
14 CFR 33.97 - Thrust reversers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... STANDARDS: AIRCRAFT ENGINES Block Tests; Turbine Aircraft Engines § 33.97 Thrust reversers. (a) If the... this subpart must be run with the reverser installed. In complying with this section, the power control... regimes of control operations are incorporated necessitating scheduling of the power-control lever motion...
Effect of obesity on posture and hip joint moments during a standing task, and trunk forward flexion motion.

PubMed

Gilleard, W; Smith, T

2007-02-01

Effects of obesity on trunk forward flexion motion in sitting and standing, and postural adaptations and hip joint moment for a standing work task. Cross-sectional comparison of obese and normal weight groups. Ten obese subjects (waist girth 121.2+/-16.8 cm, body mass index (BMI) 38.9+/-6.6 kg m(-2)) and 10 age- and height-matched normal weight subjects (waist girth 79.6+/-6.4 cm, BMI 21.7+/-1.5 kg m(-2)). Trunk motion during seated and standing forward flexion, and trunk posture, hip joint moment and hip-to-bench distance during a simulated standing work task were recorded. Forward flexion motion of the thoracic segment and thoracolumbar spine was decreased for the obese group with no change in pelvic segment and hip joint motion. Obese subjects showed a more flexed trunk posture and increased hip joint moment and hip-to-bench distance for a simulated standing work task. Decreased range of forward flexion motion, differing effects within the trunk, altered posture during a standing work task and concomitant increases in hip joint moment give insight into the aetiology of functional decrements and musculoskeletal pain seen in obesity.
Thrust Evaluation of an Arcjet Thruster Using Dimethyl Ether as a Propellant

NASA Astrophysics Data System (ADS)

Kakami, Akira; Beppu, Shinji; Maiguma, Muneyuki; Tachibana, Takeshi

This paper describes the performance of an arcjet thruster using dimethyl ether (DME) as a propellant. DME, an ether compound, has adequate characteristics for space propulsion systems; DME is storable in a liquid state without a high pressure or cryogenic device and requires no sophisticated temperature management. DME is gasified and liquefied simply by adjusting temperature, whereas hydrazine, a conventional propellant, requires an iridium-based particulate catalyst for its gasification. In this study, thrust of the designed kW-class DME arcjet thruster is measured with a torsional thrust stand. Thrust measurements show that thrust is increased with propellant mass flow rate, and that thrust using DME propellant is higher than when using nitrogen. The prototype DME arcjet thruster yields a specific impulse of 330 s, a thruster efficiency of 0.14, and a thrust of 0.19 N at 60-mg/s DME mass flow rate at 25-A discharge current. The corresponding discharge power and specific power are 2.3 kW and 39 MJ/kg.
Transpressive mantle uplift at large offset oceanic transform faults

NASA Astrophysics Data System (ADS)

Maia, M.; Briais, A.; Brunelli, D.; Ligi, M.; Sichel, S. E.; Campos, T.

2017-12-01

Large-offset transform faults deform due to changes in plate motions and local processes. At the St. Paul transform, in the Equatorial Atlantic, a large body of ultramafic rocks composed of variably serpentinized and mylonitized peridotites is presently being tectonically uplifted. We recently discovered that the origin of the regional mantle uplift is linked to long-standing compressive stresses along the transform fault (1). A positive flower structure, mainly made of mylonitized mantle rocks, can be recognized on the 200 km large push-up ridge. Compressive earthquakes mechanisms reveal seismically active thrust faults on the southern flank of the ridge . The regional transpressive stress field affects a large portion of the ridge segment south of the transform, as revealed by the presence of faults and dykes striking obliquely to the direction of the central ridge axis. A smaller thrust, affecting recent sediments, was mapped south of this segment, suggesting a regional active compressive stress field. The transpressive stress field is interpreted to derive from the propagation of the Mid-Atlantic Ridge (MAR) segment into the transform domain as a response to the enhanced melt supply at the ridge axis. The propagation forced the migration and segmentation of the transform fault southward and the formation of restraining step-overs. The process started after a counterclockwise change in plate motion at 11 Ma initially resulting in extensive stress of the transform domain. A flexural transverse ridge formed in response. Shortly after plate reorganization, the MAR segment started to propagate southwards due to the interaction of the ridge and the Sierra Leone thermal anomaly. 1- Maia et al., 2016. Extreme mantle uplift and exhumation along a transpressive transform fault Nat. Geo. doi:10.1038/ngeo2759
Microinjector for blasocysts

DOEpatents

Remenyik, Carl J.; Woychik, Richard P.; Patek, David R.; Hawk, James A.; Turner, John C.

1999-01-01

An electromechanical device for driving the tip of a microinjection cannula, or needle, through the outer barrier of a blastocyst, cell, or cell nucleus for the injection of cells or other bioactive materials. Either a flexible frame or a ram moving within a base member is employed. Cannula motion is achieved by means of a piezoelectric stack and spring return system. The thrust motion over a predetermined microscopic distance is achieved without cannula setback prior to the thrust movement. Instead of specially prepared beveled and tipped needles, standard unimproved cannulas or needles can be used.
Microinjector for blasocysts

DOEpatents

Remenyik, C.J.; Woychik, R.P.; Patek, D.R.; Hawk, J.A.; Turner, J.C.

1999-03-02

An electromechanical device is disclosed for driving the tip of a microinjection cannula, or needle, through the outer barrier of a blastocyst, cell, or cell nucleus for the injection of cells or other bioactive materials. Either a flexible frame or a ram moving within a base member is employed. Cannula motion is achieved by means of a piezoelectric stack and spring return system. The thrust motion over a predetermined microscopic distance is achieved without cannula setback prior to the thrust movement. Instead of specially prepared beveled and tipped needles, standard unimproved cannulas or needles can be used. 6 figs.
Airloads Correlation of the UH-60A Rotor Inside the 40- by 80-Foot Wind Tunnel

NASA Technical Reports Server (NTRS)

Chang, I-Chung; Norman, Thomas R.; Romander, Ethan A.

2013-01-01

The presented research validates the capability of a loosely-coupled computational fluid dynamics (CFD) and comprehensive rotorcraft analysis (CRA) code to calculate the flowfield around a rotor and test stand mounted inside a wind tunnel. The CFD/CRA predictions for the full-scale UH-60A Airloads Rotor inside the National Full-Scale Aerodynamics Complex (NFAC) 40- by 80-Foot Wind Tunnel at NASA Ames Research Center are compared with the latest measured airloads and performance data. The studied conditions include a speed sweep at constant lift up to an advance ratio of 0.4 and a thrust sweep at constant speed up to and including stall. For the speed sweep, wind tunnel modeling becomes important at advance ratios greater than 0.37 and test stand modeling becomes increasingly important as the advance ratio increases. For the thrust sweep, both the wind tunnel and test stand modeling become important as the rotor approaches stall. Despite the beneficial effects of modeling the wind tunnel and test stand, the new models do not completely resolve the current airload discrepancies between prediction and experiment.
Deepwater Fold-and-Thrust Belt Along New Caledonia's Western Margin: Relation to Post-obduction Vertical Motions

NASA Astrophysics Data System (ADS)

Collot, J.; Patriat, M.; Etienne, S.; Rouillard, P.; Soetaert, F.; Juan, C.; Marcaillou, B.; Palazzin, G.; Clerc, C.; Maurizot, P.; Pattier, F.; Tournadour, E.; Sevin, B.; Privat, A.

2017-10-01

Classically, deepwater fold-and-thrust belts are classified in two main types, depending if they result from near- or far-field stresses and the understanding of their driving and triggering mechanism is poorly known. We present a geophysical data set off the western margin of New Caledonia (SW Pacific) that reveals deformed structures of a deepwater fold-and-thrust belt that we interpret as a near-field gravity-driven system, which is not located at a rifted passive margin. The main factor triggering deformation is inferred to be oversteepening of the margin slope by postobduction isostatic rebound. Onshore erosion of abnormally dense obducted material, combined with sediment loading in the adjacent basin, has induced vertical motions that have caused oversteepening of the margin. Detailed morphobathymetric, seismic stratigraphic, and structural analysis reveals that the fold-and-thrust belt extends 200 km along the margin, and 50 km into the New Caledonia Trough. Deformation is rooted at depths greater than 5 km beneath the seafloor, affects an area of 3,500 km2, and involves a sediment volume of approximately 13,000 km3. This deformed belt is organized into an imbricate fan system of faults, and one out-of-sequence thrust fault affects the seabed. The thrust faults are deeply rooted in the basin along a low-angle floor thrust and connected to New Caledonia Island along a major detachment. This study not only provides a better knowledge of the New Caledonia margin but also provides new insight into the mechanisms that trigger deepwater fold-and-thrust belts.
Charged particle measurements on a 30-CM diameter mercury ion engine thrust beam

NASA Technical Reports Server (NTRS)

Sellen, J. M., Jr.; Komatsu, G. K.; Hoffmaster, D. K.; Kemp, R. F.

1974-01-01

Measurements of both thrust ions and charge exchange ions were made in the beam of a 30 centimeter diameter electron bombardment mercury ion thruster. A qualitative model is presented which describes magnitudes of charge exchange ion formation and motions of these ions in the weak electric field structure of the neutralized thrust beam plasma. Areas of agreement and discrepancy between observed and modeled charge exchange properties are discussed.
Store Separation Simulation of the Penguin Missile from Helicopters

DTIC Science & Technology

2006-05-01

Fin Sections – Parent Aircraft Aerodynamic Modeling • Fuselage • Wing and Pylon – Flight Simulation Features • Eqns. Of Motion • Ejectors , Thrust ...model – Lanyard model – Models for ejectors , thrust , mass, etc… – Helicopter rotor wake model – Penguin wing deployment dynamics – Penguin wing roll...umbilical, wing roll tabs, time dependent thrust and mass properties, and the incorporation of a realistic autopilot. The modeling of the unique
Jet Propulsion with Special Reference to Thrust Augmenters

NASA Technical Reports Server (NTRS)

Schubauer, G B

1933-01-01

An investigation of the possibility of using thrust augmented jets as prime movers was carried out. The augmentation was to be effected by allowing the jet to mix with the surrounding air in the presence of bodies which deflect the air set in motion by the jet.
A flow visualization study of single-arm sculling movement emulating cephalopod thrust generation

NASA Astrophysics Data System (ADS)

Kazakidi, Asimina; Gnanamanickam, Ebenezer P.; Tsakiris, Dimitris P.; Ekaterinaris, John A.

2014-11-01

In addition to jet propulsion, octopuses use arm-swimming motion as an effective means of generating bursts of thrust, for hunting, defense, or escape. The individual role of their arms, acting as thrust generators during this motion, is still under investigation, in view of an increasing robotic interest for alternative modes of propulsion, inspired by the octopus. Computational studies have revealed that thrust generation is associated with complex vortical flow patterns in the wake of the moving arm, however further experimental validation is required. Using the hydrogen bubble technique, we studied the flow disturbance around a single octopus-like robotic arm, undergoing two-stroke sculling movements in quiescent fluid. Although simplified, sculling profiles have been found to adequately capture the fundamental kinematics of the octopus arm-swimming behavior. In fact, variation of the sculling parameters alters considerably the generation of forward thrust. Flow visualization revealed the generation of complex vortical structures around both rigid and compliant arms. Increased disturbance was evident near the tip, particularly at the transitional phase between recovery and power strokes. These results are in good qualitative agreement with computational and robotic studies. Work funded by the ESF-GSRT HYDRO-ROB Project PE7(281).
Approximate approach for optimization space flights with a low thrust on the basis of sufficient optimality conditions

NASA Astrophysics Data System (ADS)

Salmin, Vadim V.

2017-01-01

Flight mechanics with a low-thrust is a new chapter of mechanics of space flight, considered plurality of all problems trajectory optimization and movement control laws and the design parameters of spacecraft. Thus tasks associated with taking into account the additional factors in mathematical models of the motion of spacecraft becomes increasingly important, as well as additional restrictions on the possibilities of the thrust vector control. The complication of the mathematical models of controlled motion leads to difficulties in solving optimization problems. Author proposed methods of finding approximate optimal control and evaluating their optimality based on analytical solutions. These methods are based on the principle of extending the class of admissible states and controls and sufficient conditions for the absolute minimum. Developed procedures of the estimation enabling to determine how close to the optimal founded solution, and indicate ways to improve them. Authors describes procedures of estimate for approximately optimal control laws for space flight mechanics problems, in particular for optimization flight low-thrust between the circular non-coplanar orbits, optimization the control angle and trajectory movement of the spacecraft during interorbital flights, optimization flights with low-thrust between arbitrary elliptical orbits Earth satellites.
Saturn Apollo Program

NASA Image and Video Library

1962-06-07

This photograph depicts the Rocketdyne static firing of the F-1 engine at the towering 76-meter Test Stand 1-C in Area 1-125 of the Edwards Air Force Base in California. The Saturn V S-IC (first) stage utilized five F-1 engines for its thrust. Each engine provided 1,500,000 pounds, for a combined thrust of 7,500,000 pounds with liquid oxygen and kerosene as its propellants.
The 2015 April 25 Gorkha Earthquake and its Aftershocks: Implications for lateral heterogeneity on the Main Himalayan Thrust

NASA Astrophysics Data System (ADS)

Mitra, S.; Kumar, A.; Priestley, K. F.

2016-12-01

The 2015 Gorkha earthquake (Mw 7.8) occurred by thrust faulting on a ˜150 km long and ˜70 km wide, locked downdip segment of the Main Himalayan Thrust (MHT), causing the Himalaya to slip SSW over the Indian Plate, and was followed by major-to-moderate aftershocks. Back projection of teleseismic P-wave and inversion of teleseismic body waves provide constraints on the geometry and kinematics of the mainshock rupture and source mechanism of aftershocks. The mainshock initiated ˜80 km west of Katmandu, close to the locking line on the MHT and propagated eastwards, along ˜117° azimuth, for a duration of ˜70 s, in multi-stage rupture. The mainshock has been modeled using four sub-events, propagating from west-to-east. The first sub-event (0-20 s) ruptured at a velocity of ˜3.5 km/s on a ˜6° N dipping flat segment of the MHT with thrust motion. The second sub-event (20-35 s) ruptured a ˜18° W dipping lateral ramp on the MHT in oblique thrust motion. The rupture velocity dropped from 3.5 km/s to 2.5 km/s, as a result of updip propagation of the rupture. The third sub-event (35-50 s) ruptured a ˜7° N dipping, eastward flat segment of the MHT with thrust motion and resulted in the largest amplitude arrivals at teleseismic distances. The fourth sub-event (50-70 s) occurred by left-lateral strike-slip motion on a steeply dipping transverse fault, at high angle to the MHT and arrested the eastward propagation of the mainshock rupture. Eastward stress build-up following the mainshock resulted in the largest aftershock (Mw 7.3), which occurred on the MHT, immediately east of the mainshock rupture. Source mechanism of moderate aftershocks reveal stress adjustment at the edges of the mainshock fault, flexural faulting on top of the downgoing Indian Plate and extensional faulting in the hanging wall of the MHT.
The 2015 April 25 Gorkha (Nepal) earthquake and its aftershocks: implications for lateral heterogeneity on the Main Himalayan Thrust

NASA Astrophysics Data System (ADS)

Kumar, Ajay; Singh, Shashwat K.; Mitra, S.; Priestley, K. F.; Dayal, Shankar

2017-02-01

The 2015 Gorkha earthquake (Mw 7.8) occurred by thrust faulting on a ˜150 km long and ˜70 km wide, locked downdip segment of the Main Himalayan Thrust (MHT), causing the Himalaya to slip SSW over the Indian Plate, and was followed by major-to-moderate aftershocks. Back projection of teleseismic P-wave and inversion of teleseismic body waves provide constraints on the geometry and kinematics of the main-shock rupture and source mechanism of aftershocks. The main-shock initiated ˜80 km west of Katmandu, close to the locking line on the MHT and propagated eastwards along ˜117° azimuth for a duration of ˜70 s, with varying rupture velocity on a heterogeneous fault surface. The main-shock has been modelled using four subevents, propagating from west-to-east. The first subevent (0-20 s) ruptured at a velocity of ˜3.5 km s- 1 on a ˜6°N dipping flat segment of the MHT with thrust motion. The second subevent (20-35 s) ruptured a ˜18° W dipping lateral ramp on the MHT in oblique thrust motion. The rupture velocity dropped from 3.5 km s- 1 to 2.5 km s- 1, as a result of updip propagation of the rupture. The third subevent (35-50 s) ruptured a ˜7°N dipping, eastward flat segment of the MHT with thrust motion and resulted in the largest amplitude arrivals at teleseismic distances. The fourth subevent (50-70 s) occurred by left-lateral strike-slip motion on a steeply dipping transverse fault, at high angle to the MHT and arrested the eastward propagation of the main-shock rupture. Eastward stress build-up following the main-shock resulted in the largest aftershock (Mw 7.3), which occurred on the MHT, immediately east of the main-shock rupture. Source mechanisms of moderate aftershocks reveal stress adjustment at the edges of the main-shock fault, flexural faulting on top of the downgoing Indian Plate and extensional faulting in the hanging wall of the MHT.
Tests of a D vented thrust deflecting nozzle behind a simulated turbofan engine

NASA Technical Reports Server (NTRS)

Watson, T. L.

1982-01-01

A D vented thrust deflecting nozzle applicable to subsonic V/STOL aircraft was tested behind a simulated turbofan engine in the verticle thrust stand. Nozzle thrust, fan operating characteristics, nozzle entrance conditions, and static pressures were measured. Nozzle performance was measured for variations in exit area and thrust deflection angle. Six core nozzle configurations, the effect of core exit axial location, mismatched core and fan stream nozzle pressure ratios, and yaw vane presence were evaluated. Core nozzle configuration affected performance at normal and engine out operating conditions. Highest vectored nozzle performance resulted for a given exit area when core and fan stream pressure were equal. Its is concluded that high nozzle performance can be maintained at both normal and engine out conditions through control of the nozzle entrance Mach number with a variable exit area.
Design and proof of concept for multi degree of freedom hydrostatically coupled dielectric elastomer actuators with roto-translational kinematics for object handling

NASA Astrophysics Data System (ADS)

De Acutis, A.; Calabrese, L.; Bau, A.; Tincani, V.; Pugno, N. M.; Bicchi, A.; De Rossi, D. E.

2018-07-01

In this article we present an upgraded design of the existing push–pull hydrostatically coupled dielectric elastomer actuator (HC-DEA) for use in the field of soft manipulators. The new design has segmented electrodes, which stand as four independent elements on the active membrane of the actuator. When properly operated, the actuator can generate both out of plane and in-plane motions resulting in a multi-degrees of freedom soft actuator able to exert both normal pushes (like a traditional HC-DEA) and tangential thrusts. This novel design makes the actuator suitable for delicate flat object transportation. In order to use the actuator in soft systems, we experimentally characterized its electromechanical transduction and modeled its contact mechanics. Finally, we show that the proposed actuator can be employed as a modular unit to develop active surfaces for flat object roto-translation.
A two-layer linear piezoelectric micromotor.

PubMed

Li, Xiaotian; Ci, Penghong; Liu, Guoxi; Dong, Shuxiang

2015-03-01

A first bending (B1) mode two-layer piezoelectric ultrasonic linear micromotor has been developed for microoptics driving applications. The piezo-vibrator of the micromotor was composed of two small Pb(Zr,Ti)O3 (PZT-5) plates, with overall dimensions and mass of only 2.0 × 2.0 × 5.0 mm(3) and 0.2 g, respectively. The proposed micromotor could operate either in single-phase voltage (standing wave) mode or two-phase voltage (traveling wave) mode to drive a slider via friction force to provide bidirectional linear motion. A large thrust of up to 0.30 N, which corresponds to a high unit volume direct driving force of 15 mN/mm(3), and a linear movement velocity of up to 230 mm/s were obtained under an applied voltage of 80 Vpp at the B1 mode resonance frequency of 174 kHz.

Neck pain: manipulating the upper back helps lessen pain and improve neck motion.

PubMed

2011-09-01

Neck pain is very common. In the United States, between 30% and 50% of people suffer from an aching neck each year. Although neck pain can be caused by injury, most of this pain results from more gradual stresses, such as particular sitting, standing, or work postures, lifting patterns, or sleeping positions. Typical neck pain can also cause headaches, pain between your shoulders, or a feeling of knots in your neck and upper back muscles. Although manual therapy, sometimes called "manipulation," is a common treatment for many types of spine pain, some people are uncomfortable having their necks manipulated. Recently, though, researchers have tested the benefits of a thrust manipulation of the upper back to treat neck pain. A study published in the September 2011 issue of JOSPT provides new insight and an evidence-based summary of the benefits of manipulating the upper back to ease and eliminate neck pain.
14 CFR 25.779 - Motion and effect of cockpit controls.

Code of Federal Regulations, 2011 CFR

2011-01-01

.... Rudder Right pedal forward for nose right. (2) Secondary. Controls Motion and effect Flaps (or auxiliary lift devices) Forward for flaps up; rearward for flaps down. Trim tabs (or equivalent) Rotate to... and auxiliary controls: (1) Powerplant. Controls Motion and effect Power or thrust Forward to increase...
14 CFR 25.779 - Motion and effect of cockpit controls.

Code of Federal Regulations, 2010 CFR

2010-01-01

.... Rudder Right pedal forward for nose right. (2) Secondary. Controls Motion and effect Flaps (or auxiliary lift devices) Forward for flaps up; rearward for flaps down. Trim tabs (or equivalent) Rotate to... and auxiliary controls: (1) Powerplant. Controls Motion and effect Power or thrust Forward to increase...
Upper cervical and upper thoracic thrust manipulation versus nonthrust mobilization in patients with mechanical neck pain: a multicenter randomized clinical trial.

PubMed

Dunning, James R; Cleland, Joshua A; Waldrop, Mark A; Arnot, Cathy F; Young, Ian A; Turner, Michael; Sigurdsson, Gisli

2012-01-01

Randomized clinical trial. To compare the short-term effects of upper cervical and upper thoracic high-velocity low-amplitude (HVLA) thrust manipulation to nonthrust mobilization in patients with neck pain. Although upper cervical and upper thoracic HVLA thrust manipulation and nonthrust mobilization are common interventions for the management of neck pain, no studies have directly compared the effects of both upper cervical and upper thoracic HVLA thrust manipulation to nonthrust mobilization in patients with neck pain. Patients completed the Neck Disability Index, the numeric pain rating scale, the flexion-rotation test for measurement of C1-2 passive rotation range of motion, and the craniocervical flexion test for measurement of deep cervical flexor motor performance. Following the baseline evaluation, patients were randomized to receive either HVLA thrust manipulation or nonthrust mobilization to the upper cervical (C1-2) and upper thoracic (T1-2) spines. Patients were reexamined 48-hours after the initial examination and again completed the outcome measures. The effects of treatment on disability, pain, C1-2 passive rotation range of motion, and motor performance of the deep cervical flexors were examined with a 2-by-2 mixed-model analysis of variance (ANOVA). One hundred seven patients satisfied the eligibility criteria, agreed to participate, and were randomized into the HVLA thrust manipulation (n = 56) and nonthrust mobilization (n = 51) groups. The 2-by-2 ANOVA demonstrated that patients with mechanical neck pain who received the combination of upper cervical and upper thoracic HVLA thrust manipulation experienced significantly (P<.001) greater reductions in disability (50.5%) and pain (58.5%) than those of the nonthrust mobilization group (12.8% and 12.6%, respectively) following treatment. In addition, the HVLA thrust manipulation group had significantly (P<.001) greater improvement in both passive C1-2 rotation range of motion and motor performance of the deep cervical flexor muscles as compared to the group that received nonthrust mobilization. The number needed to treat to avoid an unsuccessful outcome was 1.8 and 2.3 at 48-hour follow-up, using the global rating of change and Neck Disability Index cut scores, respectively. The combination of upper cervical and upper thoracic HVLA thrust manipulation is appreciably more effective in the short term than nonthrust mobilization in patients with mechanical neck pain. Therapy, level 1b.
Low-Thrust Many-Revolution Trajectory Optimization via Differential Dynamic Programming and a Sundman Transformation

NASA Technical Reports Server (NTRS)

Aziz, Jonathan D.; Parker, Jeffrey S.; Scheeres, Daniel J.; Englander, Jacob A.

2017-01-01

Low-thrust trajectories about planetary bodies characteristically span a high count of orbital revolutions. Directing the thrust vector over many revolutions presents a challenging optimization problem for any conventional strategy. This paper demonstrates the tractability of low-thrust trajectory optimization about planetary bodies by applying a Sundman transformation to change the independent variable of the spacecraft equations of motion to the eccentric anomaly and performing the optimization with differential dynamic programming. Fuel-optimal geocentric transfers are shown in excess of 1000 revolutions while subject to Earths J2 perturbation and lunar gravity.
Target thrust measurement for applied-field magnetoplasmadynamic thruster

NASA Astrophysics Data System (ADS)

Wang, B.; Yang, W.; Tang, H.; Li, Z.; Kitaeva, A.; Chen, Z.; Cao, J.; Herdrich, G.; Zhang, K.

2018-07-01

In this paper, we present a flat target thrust stand which is designed to measure the thrust of a steady-state applied-field magnetoplasmadynamic thruster (AF-MPDT). In our experiments we varied target-thruster distances and target size to analyze their influence on the target thrust measurement results. The obtained thrust-distance curves increase to local maximum and then decreases with the increasing distance, which means that the plume of the AF-MPDT can still accelerate outside the thruster exit. The peak positions are related to the target sizes: larger targets can make the peak positions further from the thruster and decrease the measurement errors. To further improve the reliability of measurement results, a thermal equilibrium assumption combined with Knudsen’s cosine law is adapted to analyze the error caused by the back stream of plume particles. Under the assumption, the error caused by particle backflow is no more than 3.6% and the largest difference between the measured thrust and the theoretical thrust is 14%. Moreover, it was verified that target thrust measurement can disturb the working of the AF-MPD thruster, and the influence on the thrust measurement result is no more than 1% in our experiment.
Postural control during quiet bipedal standing in rats

PubMed Central

Sato, Yota; Fujiki, Soichiro; Sato, Yamato; Aoi, Shinya; Tsuchiya, Kazuo; Yanagihara, Dai

2017-01-01

The control of bipedal posture in humans is subject to non-ideal conditions such as delayed sensation and heartbeat noise. However, the controller achieves a high level of functionality by utilizing body dynamics dexterously. In order to elucidate the neural mechanism responsible for postural control, the present study made use of an experimental setup involving rats because they have more accessible neural structures. The experimental design requires rats to stand bipedally in order to obtain a water reward placed in a water supplier above them. Their motions can be measured in detail using a motion capture system and a force plate. Rats have the ability to stand bipedally for long durations (over 200 s), allowing for the construction of an experimental environment in which the steady standing motion of rats could be measured. The characteristics of the measured motion were evaluated based on aspects of the rats’ intersegmental coordination and power spectrum density (PSD). These characteristics were compared with those of the human bipedal posture. The intersegmental coordination of the standing rats included two components that were similar to that of standing humans: center of mass and trunk motion. The rats’ PSD showed a peak at approximately 1.8 Hz and the pattern of the PSD under the peak frequency was similar to that of the human PSD. However, the frequencies were five times higher in rats than in humans. Based on the analysis of the rats’ bipedal standing motion, there were some common characteristics between rat and human standing motions. Thus, using standing rats is expected to be a powerful tool to reveal the neural basis of postural control. PMID:29244818
Thrust generation by a heaving flexible foil: Resonance, nonlinearities, and optimality

NASA Astrophysics Data System (ADS)

Paraz, Florine; Schouveiler, Lionel; Eloy, Christophe

2016-01-01

Flexibility of marine animal fins has been thought to enhance swimming performance. However, despite numerous experimental and numerical studies on flapping flexible foils, there is still no clear understanding of the effect of flexibility and flapping amplitude on thrust generation and swimming efficiency. Here, to address this question, we combine experiments on a model system and a weakly nonlinear analysis. Experiments consist in immersing a flexible rectangular plate in a uniform flow and forcing this plate into a heaving motion at its leading edge. A complementary theoretical model is developed assuming a two-dimensional inviscid problem. In this model, nonlinear effects are taken into account by considering a transverse resistive drag. Under these hypotheses, a modal decomposition of the system motion allows us to predict the plate response amplitude and the generated thrust, as a function of the forcing amplitude and frequency. We show that this model can correctly predict the experimental data on plate kinematic response and thrust generation, as well as other data found in the literature. We also discuss the question of efficiency in the context of bio-inspired propulsion. Using the proposed model, we show that the optimal propeller for a given thrust and a given swimming speed is achieved when the actuating frequency is tuned to a resonance of the system, and when the optimal forcing amplitude scales as the square root of the required thrust.
35. Historic photo of Building 202 test stand with damage ...

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

35. Historic photo of Building 202 test stand with damage to twenty-thousand-pound-thrust rocket engine related to failure during testing, September 16, 1958. On file at NASA Plumbrook Research Center, Sandusky, Ohio. NASA photo number C-48704. - Rocket Engine Testing Facility, GRC Building No. 202, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH
Preliminary Results of Performance Measurements on a Cylindrical Hall-Effect Thruster with Magnetic Field Generated by Permanent Magnets

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Raitses, Y.; Merino, E.; Fisch, N. J.

2008-01-01

The performance of a low-power cylindrical Hall thruster, which more readily lends itself to miniaturization and low-power operation than a conventional (annular) Hall thruster, was measured using a planar plasma probe and a thrust stand. The field in the cylindrical thruster was produced using permanent magnets, promising a power reduction over previous cylindrical thruster iterations that employed electromagnets to generate the required magnetic field topology. Two sets of ring-shaped permanent magnets are used, and two different field configurations can be produced by reorienting the poles of one magnet relative to the other. A plasma probe measuring ion flux in the plume is used to estimate the current utilization for the two magnetic configurations. The measurements indicate that electron transport is impeded much more effectively in one configuration, implying a higher thrust efficiency. Preliminary thruster performance measurements on this configuration were obtained over a power range of 100-250 W. The thrust levels over this power range were 3.5-6.5 mN, with anode efficiencies and specific impulses spanning 14-19% and 875- 1425 s, respectively. The magnetic field in the thruster was lower for the thrust measurements than the plasma probe measurements due to heating and weakening of the permanent magnets, reducing the maximum field strength from 2 kG to roughly 750-800 G. The discharge current levels observed during thrust stand testing were anomalously high compared to those levels measured in previous experiments with this thruster.
Tsien's method for generating non-Keplerian trajectories. Part 2: The question of thrust to orbit a sphere and the restricted three-body problem

NASA Technical Reports Server (NTRS)

Murad, P. A.

1993-01-01

Tsien's method is extended to treat the orbital motion of a body undergoing accelerations and decelerations. A generalized solution is discussed for the generalized case where a body undergoes azimuthal and radial thrust and the problem is further simplified for azimuthal thrust alone. Judicious selection of thrust could generate either an elliptic or hyperbolic trajectory. This is unexpected especially when the body has only enough energy for a lower state trajectory. The methodology is extended treating the problem of vehicle thrust for orbiting a sphere and vehicle thrust within the classical restricted three-body problem. Results for the latter situation can produce hyperbolic trajectories through eigen value decomposition. Since eigen values for no-thrust can be imaginary, thrust can generate real eigen values to describe hyperbolic trajectories. Keplerian dynamics appears to represent but a small subset of a much larger non-Keplerian domain especially when thrust effects are considered. The need for high thrust long duration space-based propulsion systems for changing a trajectory's canonical form is clearly demonstrated.
High-speed engine/component performance assessment using exergy and thrust-based methods

NASA Technical Reports Server (NTRS)

Riggins, D. W.

1996-01-01

This investigation summarizes a comparative study of two high-speed engine performance assessment techniques based on energy (available work) and thrust-potential (thrust availability). Simple flow-fields utilizing Rayleigh heat addition and one-dimensional flow with friction are used to demonstrate the fundamental inability of conventional energy techniques to predict engine component performance, aid in component design, or accurately assess flow losses. The use of the thrust-based method on these same examples demonstrates its ability to yield useful information in all these categories. Energy and thrust are related and discussed from the stand-point of their fundamental thermodynamic and fluid dynamic definitions in order to explain the differences in information obtained using the two methods. The conventional definition of energy is shown to include work which is inherently unavailable to an aerospace Brayton engine. An engine-based energy is then developed which accurately accounts for this inherently unavailable work; performance parameters based on this quantity are then shown to yield design and loss information equivalent to the thrust-based method.
7. MOTION PICTURE CAMERA STAND AT BUILDING 8768. Edwards ...

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

7. MOTION PICTURE CAMERA STAND AT BUILDING 8768. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Observation Bunkers for Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA
Two-Dimensional Motions of Rockets

ERIC Educational Resources Information Center

Kang, Yoonhwan; Bae, Saebyok

2007-01-01

We analyse the two-dimensional motions of the rockets for various types of rocket thrusts, the air friction and the gravitation by using a suitable representation of the rocket equation and the numerical calculation. The slope shapes of the rocket trajectories are discussed for the three types of rocket engines. Unlike the projectile motions, the…
Evaluation of aperture cover tank vent nozzles for the IRAS spacecraft

NASA Technical Reports Server (NTRS)

Richter, R.

1983-01-01

The influence of coefficients for the three axes of the Infrared Astronomical Satellite (IRAS) were established to determine the maximum allowable thrust difference between the two vent nozzles of the aperture cover tank low thrust vent system and their maximum misalignment. Test data generated by flow and torque measurements permitted the selection of two nozzles whose thrust differential was within the limit of the attitude control capability. Based on thrust stand data, a thrust vector misalignment was indicated that was slightly higher than permissible for the worst case, i.e., considerable degradation of the torque capacity of the attitude control system combined with venting of helium at its upper limit. The probability of destabilizing the IRAS spacecraft by activating the venting system appeared to be very low. The selection and mounting of the nozzles have satisfied all the requirements for the safe venting of helium.
Artificial equilibrium points in binary asteroid systems with continuous low-thrust

NASA Astrophysics Data System (ADS)

Bu, Shichao; Li, Shuang; Yang, Hongwei

2017-08-01

The positions and dynamical characteristics of artificial equilibrium points (AEPs) in the vicinity of a binary asteroid with continuous low-thrust are studied. The restricted ellipsoid-ellipsoid model of binary system is employed for the binary asteroid system. The positions of AEPs are obtained by this model. It is found that the set of the point L1 or L2 forms a shape of an ellipsoid while the set of the point L3 forms a shape like a "banana". The effect of the continuous low-thrust on the feasible region of motion is analyzed by zero velocity curves. Because of using the low-thrust, the unreachable region can become reachable. The linearized equations of motion are derived for stability's analysis. Based on the characteristic equation of the linearized equations, the stability conditions are derived. The stable regions of AEPs are investigated by a parametric analysis. The effect of the mass ratio and ellipsoid parameters on stable region is also discussed. The results show that the influence of the mass ratio on the stable regions is more significant than the parameters of ellipsoid.
Inertia and Couple-Stress Effects in a Curvilinear Thrust Hydrostatic Bearing

NASA Astrophysics Data System (ADS)

Walicka, A.; Jurczak, P.; Falicki, J.

2017-08-01

The flow of a couple-stress lubricant in a clearance of a curvilinear thrust hydrostatic bearing with impermeable walls is considered. The flow in the bearing clearance is considered with inertia forces. The equations of motion are solved by an averaged inertia method. As a result, the formulae for pressure distributions without and with inertia effects were obtained. Radial thrust bearings and spherical bearings are discussed as numerical examples. It is shown that inertia effects influence the bearing performance considerably.
Precarious rock and overturned transformer evidence for ground shaking in the Ms 7.7 Kern County earthquake: An analog for disastrous shaking from a major thrust fault in the Los Angeles basin

USGS Publications Warehouse

Brune, J.N.; Anooshehpoor, A.; Shi, B.; Zheng, Yen

2004-01-01

Precariously balanced rocks and overturned transformers in the vicinity of the White Wolf fault provide constraints on ground motion during the 1952 Ms 7.7 Kern County earthquake, a possible analog for an anticipated large earthquake in the Los Angeles basin (Shaw et al., 2002; Dolan et al., 2003). On the northeast part of the fault preliminary estimates of ground motion on the footwall give peak accelerations considerably lower than predicted by standard regression curves. On the other hand, on the hanging-wall, there is evidence of intense ground shattering and lack of precarious rocks, consistent with the intense hanging-wall accelerations suggested by foam-rubber modeling, numerical modeling, and observations from previous thrust fault earthquakes. There is clear evidence of the effects of rupture directivity in ground motions on the hanging-wall side of the fault (from both precarious rocks and numerical simulations). On the southwest part of the fault, which is covered by sediments, the thrust fault did not reach the surface ("blind" thrust). Overturned and damaged transformers indicate significant transfer of energy from the hanging wall to the footwall, an effect that may not be as effective when the rupture reaches the surface (is not "blind"). Transformers near the up-dip projection of the fault tip have been damaged or overturned on both the hanging-wall and footwall sides of the fault. The transfer of energy is confirmed in a numerical lattice model and could play an important role in a similar situation in Los Angeles. We suggest that the results of this study can provide important information for estimating the effects of a large thrust fault rupture in the Los Angeles basin, specially given the fact that there is so little instrumental data from large thrust fault earthquakes.
A guidance and navigation system for continuous low thrust vehicles. M.S. Thesis

NASA Technical Reports Server (NTRS)

Tse, C. J. C.

1973-01-01

A midcourse guidance and navigation system for continuous low thrust vehicles is described. A set of orbit elements, known as the equinoctial elements, are selected as the state variables. The uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time nominal trajectory is defined and the equation of motion and the measurement equation are linearized about this nominal trajectory. An exponential cost criterion is constructed and a linear feedback guidance law is derived to control the thrusting direction of the engine. Using this guidance law, the vehicle will fly in a trajectory neighboring the nominal trajectory. The extended Kalman filter is used for state estimation. Finally a short mission using this system is simulated. The results indicate that this system is very efficient for short missions.
Hall Effect Thruster Ground Testing Challenges

DTIC Science & Technology

2009-08-18

the specic impulse, g is Earth’s gravitational constant, η is the thrust efficiency, ṁ is the propellant...lines form a composite spring with an effective spring constant of K . The thruster displaces the inverted pendulum a distance x, and the thrust stand...destabilizing force as shown in Eqn. 5. x = T K − Mgh (5) The effective spring constant is adjusted such that the unstable condition of K = Mg/h is avoided,

Sensorimotor Learning of Acupuncture Needle Manipulation Using Visual Feedback

PubMed Central

Jung, Won-Mo; Lim, Jinwoong; Lee, In-Seon; Park, Hi-Joon; Wallraven, Christian; Chae, Younbyoung

2015-01-01

Objective Humans can acquire a wide variety of motor skills using sensory feedback pertaining to discrepancies between intended and actual movements. Acupuncture needle manipulation involves sophisticated hand movements and represents a fundamental skill for acupuncturists. We investigated whether untrained students could improve their motor performance during acupuncture needle manipulation using visual feedback (VF). Methods Twenty-one untrained medical students were included, randomly divided into concurrent (n = 10) and post-trial (n = 11) VF groups. Both groups were trained in simple lift/thrusting techniques during session 1, and in complicated lift/thrusting techniques in session 2 (eight training trials per session). We compared the motion patterns and error magnitudes of pre- and post-training tests. Results During motion pattern analysis, both the concurrent and post-trial VF groups exhibited greater improvements in motion patterns during the complicated lifting/thrusting session. In the magnitude error analysis, both groups also exhibited reduced error magnitudes during the simple lifting/thrusting session. For the training period, the concurrent VF group exhibited reduced error magnitudes across all training trials, whereas the post-trial VF group was characterized by greater error magnitudes during initial trials, which gradually reduced during later trials. Conclusions Our findings suggest that novices can improve the sophisticated hand movements required for acupuncture needle manipulation using sensorimotor learning with VF. Use of two types of VF can be beneficial for untrained students in terms of learning how to manipulate acupuncture needles, using either automatic or cognitive processes. PMID:26406248
Saturn Apollo Program

NASA Image and Video Library

1968-06-01

This photograph depicts a test firing of an F-1 engine at the F-1 engine test stand in the west test area of the Marshall Space Flight Center. This engine produced 1,500,000 pounds of thrust using liquid oxygen and RP-1, which is a derivative of kerosene. The F-1 engine test stand was constructed in 1963 to assist in the development of the F-1 engine.
Laminar Motion of the Incompressible Fluids in Self-Acting Thrust Bearings with Spiral Grooves

PubMed Central

Velescu, Cornel; Popa, Nicolae Calin

2014-01-01

We analyze the laminar motion of incompressible fluids in self-acting thrust bearings with spiral grooves with inner or external pumping. The purpose of the study is to find some mathematical relations useful to approach the theoretical functionality of these bearings having magnetic controllable fluids as incompressible fluids, in the presence of a controllable magnetic field. This theoretical study approaches the permanent motion regime. To validate the theoretical results, we compare them to some experimental results presented in previous papers. The laminar motion of incompressible fluids in bearings is described by the fundamental equations of fluid dynamics. We developed and particularized these equations by taking into consideration the geometrical and functional characteristics of these hydrodynamic bearings. Through the integration of the differential equation, we determined the pressure and speed distributions in bearings with length in the “pumping” direction. These pressure and speed distributions offer important information, both quantitative (concerning the bearing performances) and qualitative (evidence of the viscous-inertial effects, the fluid compressibility, etc.), for the laminar and permanent motion regime. PMID:24526896
Laminar motion of the incompressible fluids in self-acting thrust bearings with spiral grooves.

PubMed

Velescu, Cornel; Popa, Nicolae Calin

2014-01-01

We analyze the laminar motion of incompressible fluids in self-acting thrust bearings with spiral grooves with inner or external pumping. The purpose of the study is to find some mathematical relations useful to approach the theoretical functionality of these bearings having magnetic controllable fluids as incompressible fluids, in the presence of a controllable magnetic field. This theoretical study approaches the permanent motion regime. To validate the theoretical results, we compare them to some experimental results presented in previous papers. The laminar motion of incompressible fluids in bearings is described by the fundamental equations of fluid dynamics. We developed and particularized these equations by taking into consideration the geometrical and functional characteristics of these hydrodynamic bearings. Through the integration of the differential equation, we determined the pressure and speed distributions in bearings with length in the "pumping" direction. These pressure and speed distributions offer important information, both quantitative (concerning the bearing performances) and qualitative (evidence of the viscous-inertial effects, the fluid compressibility, etc.), for the laminar and permanent motion regime.
Low-Thrust Many-Revolution Trajectory Optimization via Differential Dynamic Programming and a Sundman Transformation

NASA Astrophysics Data System (ADS)

Aziz, Jonathan D.; Parker, Jeffrey S.; Scheeres, Daniel J.; Englander, Jacob A.

2018-01-01

Low-thrust trajectories about planetary bodies characteristically span a high count of orbital revolutions. Directing the thrust vector over many revolutions presents a challenging optimization problem for any conventional strategy. This paper demonstrates the tractability of low-thrust trajectory optimization about planetary bodies by applying a Sundman transformation to change the independent variable of the spacecraft equations of motion to an orbit angle and performing the optimization with differential dynamic programming. Fuel-optimal geocentric transfers are computed with the transfer duration extended up to 2000 revolutions. The flexibility of the approach to higher fidelity dynamics is shown with Earth's J 2 perturbation and lunar gravity included for a 500 revolution transfer.
Low-Thrust Many-Revolution Trajectory Optimization via Differential Dynamic Programming and a Sundman Transformation

NASA Astrophysics Data System (ADS)

Aziz, Jonathan D.; Parker, Jeffrey S.; Scheeres, Daniel J.; Englander, Jacob A.

2018-06-01

Low-thrust trajectories about planetary bodies characteristically span a high count of orbital revolutions. Directing the thrust vector over many revolutions presents a challenging optimization problem for any conventional strategy. This paper demonstrates the tractability of low-thrust trajectory optimization about planetary bodies by applying a Sundman transformation to change the independent variable of the spacecraft equations of motion to an orbit angle and performing the optimization with differential dynamic programming. Fuel-optimal geocentric transfers are computed with the transfer duration extended up to 2000 revolutions. The flexibility of the approach to higher fidelity dynamics is shown with Earth's J 2 perturbation and lunar gravity included for a 500 revolution transfer.
Dynamic modeling and motion simulation for a winged hybrid-driven underwater glider

NASA Astrophysics Data System (ADS)

Wang, Shu-Xin; Sun, Xiu-Jun; Wang, Yan-Hui; Wu, Jian-Guo; Wang, Xiao-Ming

2011-03-01

PETREL, a winged hybrid-driven underwater glider is a novel and practical marine survey platform which combines the features of legacy underwater glider and conventional AUV (autonomous underwater vehicle). It can be treated as a multi-rigid-body system with a floating base and a particular hydrodynamic profile. In this paper, theorems on linear and angular momentum are used to establish the dynamic equations of motion of each rigid body and the effect of translational and rotational motion of internal masses on the attitude control are taken into consideration. In addition, due to the unique external shape with fixed wings and deflectable rudders and the dual-drive operation in thrust and glide modes, the approaches of building dynamic model of conventional AUV and hydrodynamic model of submarine are introduced, and the tailored dynamic equations of the hybrid glider are formulated. Moreover, the behaviors of motion in glide and thrust operation are analyzed based on the simulation and the feasibility of the dynamic model is validated by data from lake field trials.
AHPCRC - Army High Performance Computing Research Center

DTIC Science & Technology

2008-01-01

University) Birds and insects use complex flapping and twisting wing motions to maneuver, hover, avoid obstacles, and maintain or regain their...vehicles for use in sensing, surveillance, and wireless communications. HPC simulations examine plunging, pitching, and twisting motions of aeroelastic...wings, to optimize the amplitudes and frequencies of flapping and twisting motions for the maximum amount of thrust. Several methods of calculation
Three-dimensional knee motion before and after high tibial osteotomy for medial knee osteoarthritis.

PubMed

Takemae, Takashi; Omori, Go; Nishino, Katsutoshi; Terajima, Kazuhiro; Koga, Yoshio; Endo, Naoto

2006-11-01

High tibial osteotomy (HTO) is an established surgical option for treating medial knee osteoarthritis. HTO moves the mechanical load on the knee joint from the medial compartment to the lateral compartment by changing the leg alignment, but the effects of the operation remain unclear. The purpose of this study was to evaluate the change in three-dimensional knee motion before and after HTO, focusing on lateral thrust and screw home movement, and to investigate the relationship between the change in knee motion and the clinical results. A series of 19 patients with medial knee osteoarthritis who had undergone HTO were evaluated. We performed a clinical assessment, radiological evaluation, and motion analysis at 2.4 years postoperatively. The clinical assessment was performed using the Japanese Orthopaedic Association knee score. The score was significantly improved in all patients after operation. Motion analysis revealed that lateral thrust, which was observed in 18 of the 20 knees before operation, was reduced to 7 knees after operation. Regarding active terminal extension of the knee, three patterns of rotational movement were observed before operation: screw home movement (external rotation), reverse screw home movement (internal rotation), and no rotation. By contrast, after operation, only reverse screw home movement and no rotation were observed; the screw home movement disappeared in all patients. In the knees with reverse screw home movement after operation, the preoperative score was significantly lower than those in the knees with no rotation after operation. Kinetically, HTO was useful for suppressing lateral thrust in medial knee osteoarthritis, although the rotational movement of the knee joint was unchanged.
Extended analytical formulas for the perturbed Keplerian motion under a constant control acceleration

NASA Astrophysics Data System (ADS)

Zuiani, Federico; Vasile, Massimiliano

2015-03-01

This paper presents a set of analytical formulae for the perturbed Keplerian motion of a spacecraft under the effect of a constant control acceleration. The proposed set of formulae can treat control accelerations that are fixed in either a rotating or inertial reference frame. Moreover, the contribution of the zonal harmonic is included in the analytical formulae. It will be shown that the proposed analytical theory allows for the fast computation of long, multi-revolution spirals while maintaining good accuracy. The combined effect of different perturbations and of the shadow regions due to solar eclipse is also included. Furthermore, a simplified control parameterisation is introduced to optimise thrusting patterns with two thrust arcs and two cost arcs per revolution. This simple parameterisation is shown to ensure enough flexibility to describe complex low thrust spirals. The accuracy and speed of the proposed analytical formulae are compared against a full numerical integration with different integration schemes. An averaging technique is then proposed as an application of the analytical formulae. Finally, the paper presents an example of design of an optimal low-thrust spiral to transfer a spacecraft from an elliptical to a circular orbit around the Earth.
A-1 modification work under way

NASA Technical Reports Server (NTRS)

2008-01-01

Phil Schemanski of Pratt & Whitney Rocketdyne removes equipment inside the thrust drum on the A-1 Test Stand as part of a comprehensive modification project to prepare for testing the new J-2X engine.
A self-running standing wave-type bidirectional slider for the ultrasonically levitated thin linear stage.

PubMed

Koyama, Daisuke; Takei, Hiroyuki; Nakamura, Kentaro; Ueha, Sadayuki

2008-08-01

A slider for a self-running standing wave-type, ultrasonically levitated, thin linear stage is discussed. The slider can be levitated and moved using acoustic radiation force and acoustic streaming. The slider has a simple configuration and consists of an aluminum vibrating plate and a piezoelectric zirconate titanate (PZT) element. The large asymmetric vibration distribution for the high thrust and levitation performance was obtained by adjusting the configuration determined by finite elemental analysis (FEA). As a preliminary step, the computed results of the sound pressure distribution in the 1-mm air gap by FEA was com pared with experimental results obtained using a fiber optic probe. The direction of the total driving force for the acoustic streaming in the small air gap was estimated by the sound pressure distribution calculated by FEA, and it was found that the direction of the acoustic streaming could be altered by controlling the vibration mode of the slider. The flexural standing wave could be generated along the vibrating plate near the frequencies predicted based on the FEA results. The slider could be levitated by the acoustic radiation force radiated from its own vibrating plate at several frequencies. The slider could be moved in the negative and positive directions at 68 kHz and 69 kHz, which correspond to the results computed by FEA, with the asymmetric vibration distribution of the slider's vibrating plate. Larger thrust could be obtained with the smaller levitation distance, and the maximum thrust was 19 mN.
Thrust stand evaluation of engine performance improvement algorithms in an F-15 airplane

NASA Technical Reports Server (NTRS)

Conners, Timothy R.

1992-01-01

Results are presented from the evaluation of the performance seeking control (PSC) optimization algorithm developed by Smith et al. (1990) for F-15 aircraft, which optimizes the quasi-steady-state performance of an F100 derivative turbofan engine for several modes of operation. The PSC algorithm uses onboard software engine model that calculates thrust, stall margin, and other unmeasured variables for use in the optimization. Comparisons are presented between the load cell measurements, PSC onboard model thrust calculations, and posttest state variable model computations. Actual performance improvements using the PSC algorithm are presented for its various modes. The results of using PSC algorithm are compared with similar test case results using the HIDEC algorithm.
Direct measurement of the impulse in a magnetic thrust chamber system for laser fusion rocket

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maeno, Akihiro; Yamamoto, Naoji; Nakashima, Hideki

2011-08-15

An experiment is conducted to measure an impulse for demonstrating a magnetic thrust chamber system for laser fusion rocket. The impulse is produced by the interaction between plasma and magnetic field. In the experiment, the system consists of plasma and neodymium permanent magnets. The plasma is created by a single-beam laser aiming at a polystyrene spherical target. The impulse is 1.5 to 2.2 {mu}Ns by means of a pendulum thrust stand, when the laser energy is 0.7 J. Without magnetic field, the measured impulse is found to be zero. These results indicate that the system for generating impulse is working.
Effects of bleed air extraction on thrust levels on the F404-GE-400 turbofan engine

NASA Technical Reports Server (NTRS)

Yuhas, Andrew J.; Ray, Ronald J.

1992-01-01

A ground test was performed to determine the effects of compressor bleed flow extraction on the performance of F404-GE-400 afterburning turbofan engines. The two engines were installed in the F/A-18 High Alpha Research Vehicle at the NASA Dryden Flight Research Facility. A specialized bleed ducting system was installed onto the aircraft to control and measure engine bleed airflow while the aircraft was tied down to a thrust measuring stand. The test was conducted on each engine and at various power settings. The bleed air extraction levels analyzed included flow rates above the manufacturer's maximum specification limit. The measured relationship between thrust and bleed flow extraction was shown to be essentially linear at all power settings with an increase in bleed flow causing a corresponding decrease in thrust. A comparison with the F404-GE-400 steady-state engine simulation showed the estimation to be within +/- 1 percent of measured thrust losses for large increases in bleed flow rate.
Initial Thrust Measurements of Marshall's Ion-ioN Thruster

NASA Technical Reports Server (NTRS)

Schloeder, Natalie R.; Scogin, Tyler; Liu, Thomas M.; Walker, Mitchell L. R.; Polzin, Kurt A.; Dankanich, John W.; Aanesland, Ane

2015-01-01

Electronegative ion thrusters are a variation of tradition gridded ion thruster technology differentiated by the production and acceleration of both positive and negative ions. Benefits of electronegative ion thrusters include the elimination of lifetime-limiting cathodes from the thruster architecture and the ability to generate appreciable thrust from both charge species. Following the continued development of electronegative ion thruster technology as exhibited by the PEGASES (Plasma Propulsion with Electronegative GASES) thruster, direct thrust measurements are required to push interest in electronegative ion thruster technology forward. For this work, direct thrust measurements of the MINT (Marshall's Ion-ioN Thruster) will be taken on a hanging pendulum thrust stand for propellant mixtures of Sulfur Hexafluoride and Argon at volumetric flow rates of 5-25 sccm at radio frequency power levels of 100-600 watts at a radio frequency of 13.56 MHz. Acceleration grid operation is operated using a square waveform bias of +/-300 volts at a frequency of 25 kHz.
Saturn Apollo Program

NASA Image and Video Library

1967-09-09

This photograph depicts the F-1 engine firing in the Marshall Space Flight Center’s F-1 Engine Static Test Stand. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. It is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. The foundation of the stand is keyed into the bedrock approximately 40 feet below grade.
Flutter and forced response of mistuned rotors using standing wave analysis

NASA Technical Reports Server (NTRS)

Dugundji, J.; Bundas, D. J.

1983-01-01

A standing wave approach is applied to the analysis of the flutter and forced response of tuned and mistuned rotors. The traditional traveling wave cascade airforces are recast into standing wave arbitrary motion form using Pade approximants, and the resulting equations of motion are written in the matrix form. Applications for vibration modes, flutter, and forced response are discussed. It is noted that the standing wave methods may prove to be more versatile for dealing with certain applications, such as coupling flutter with forced response and dynamic shaft problems, transient impulses on the rotor, low-order engine excitation, bearing motions, and mistuning effects in rotors.
Flutter and forced response of mistuned rotors using standing wave analysis

NASA Technical Reports Server (NTRS)

Bundas, D. J.; Dungundji, J.

1983-01-01

A standing wave approach is applied to the analysis of the flutter and forced response of tuned and mistuned rotors. The traditional traveling wave cascade airforces are recast into standing wave arbitrary motion form using Pade approximants, and the resulting equations of motion are written in the matrix form. Applications for vibration modes, flutter, and forced response are discussed. It is noted that the standing wave methods may prove to be more versatile for dealing with certain applications, such as coupling flutter with forced response and dynamic shaft problems, transient impulses on the rotor, low-order engine excitation, bearing motion, and mistuning effects in rotors.
Biomimetic propulsion under random heaving conditions, using active pitch control

NASA Astrophysics Data System (ADS)

Politis, Gerasimos; Politis, Konstantinos

2014-05-01

Marine mammals travel long distances by utilizing and transforming wave energy to thrust through proper control of their caudal fin. On the other hand, manmade ships traveling in a wavy sea store large amounts of wave energy in the form of kinetic energy for heaving, pitching, rolling and other ship motions. A natural way to extract this energy and transform it to useful propulsive thrust is by using a biomimetic wing. The aim of this paper is to show how an actively pitched biomimetic wing could achieve this goal when it performs a random heaving motion. More specifically, we consider a biomimetic wing traveling with a given translational velocity in an infinitely extended fluid and performing a random heaving motion with a given energy spectrum which corresponds to a given sea state. A formula is invented by which the instantaneous pitch angle of the wing is determined using the heaving data of the current and past time steps. Simulations are then performed for a biomimetic wing at different heave energy spectra, using an indirect Source-Doublet 3-D-BEM, together with a time stepping algorithm capable to track the random motion of the wing. A nonlinear pressure type Kutta condition is applied at the trailing edge of the wing. With a mollifier-based filtering technique, the 3-D unsteady rollup pattern created by the random motion of the wing is calculated without any simplifying assumptions regarding its geometry. Calculated unsteady forces, moments and useful power, show that the proposed active pitch control always results in thrust producing motions, with significant propulsive power production and considerable beneficial stabilizing action to ship motions. Calculation of the power required to set the pitch angle prove it to be a very small percentage of the useful power and thus making the practical application of the device very tractable.

An inventory of aeronautical ground research facilities. Volume 2: Air breathing engine test facilities

NASA Technical Reports Server (NTRS)

Pirrello, C. J.; Hardin, R. D.; Heckart, M. V.; Brown, K. R.

1971-01-01

The inventory covers free jet and direct connect altitude cells, sea level static thrust stands, sea level test cells with ram air, and propulsion wind tunnels. Free jet altitude cells and propulsion wind tunnels are used for evaluation of complete inlet-engine-exhaust nozzle propulsion systems under simulated flight conditions. These facilities are similar in principal of operation and differ primarily in test section concept. The propulsion wind tunnel provides a closed test section and restrains the flow around the test specimen while the free jet is allowed to expand freely. A chamber of large diameter about the free jet is provided in which desired operating pressure levels may be maintained. Sea level test cells with ram air provide controlled, conditioned air directly to the engine face for performance evaluation at low altitude flight conditions. Direct connect altitude cells provide a means of performance evaluation at simulated conditions of Mach number and altitude with air supplied to the flight altitude conditions. Sea level static thrust stands simply provide an instrumented engine mounting for measuring thrust at zero airspeed. While all of these facilities are used for integrated engine testing, a few provide engine component test capability.
Adaptive Failure Compensation for Aircraft Flight Control Using Engine Differentials: Regulation

NASA Technical Reports Server (NTRS)

Yu, Liu; Xidong, Tang; Gang, Tao; Joshi, Suresh M.

2005-01-01

The problem of using engine thrust differentials to compensate for rudder and aileron failures in aircraft flight control is addressed in this paper in a new framework. A nonlinear aircraft model that incorporates engine di erentials in the dynamic equations is employed and linearized to describe the aircraft s longitudinal and lateral motion. In this model two engine thrusts of an aircraft can be adjusted independently so as to provide the control flexibility for rudder or aileron failure compensation. A direct adaptive compensation scheme for asymptotic regulation is developed to handle uncertain actuator failures in the linearized system. A design condition is specified to characterize the system redundancy needed for failure compensation. The adaptive regulation control scheme is applied to the linearized model of a large transport aircraft in which the longitudinal and lateral motions are coupled as the result of using engine thrust differentials. Simulation results are presented to demonstrate the effectiveness of the adaptive compensation scheme.
Response of high-rise and base-isolated buildings to a hypothetical M w 7.0 blind thrust earthquake

USGS Publications Warehouse

Heaton, T.H.; Hall, J.F.; Wald, D.J.; Halling, M.W.

1995-01-01

High-rise flexible-frame buildings are commonly considered to be resistant to shaking from the largest earthquakes. In addition, base isolation has become increasingly popular for critical buildings that should still function after an earthquake. How will these two types of buildings perform if a large earthquake occurs beneath a metropolitan area? To answer this question, we simulated the near-source ground motions of a Mw 7.0 thrust earthquake and then mathematically modeled the response of a 20-story steel-frame building and a 3-story base-isolated building. The synthesized ground motions were characterized by large displacement pulses (up to 2 meters) and large ground velocities. These ground motions caused large deformation and possible collapse of the frame building, and they required exceptional measures in the design of the base-isolated building if it was to remain functional.
Application of nonlinear adaptive motion washout to transport ground-handling simulation

NASA Technical Reports Server (NTRS)

Parrish, R. V.; Martin, D. J., Jr.

1983-01-01

The application of a nonlinear coordinated adaptive motion washout to the transport ground-handling environment is documented. Additions to both the aircraft math model and the motion washout system are discussed. The additions to the simulated-aircraft math model provided improved modeling fidelity for braking and reverse-thrust application, and the additions to the motion-base washout system allowed transition from the desired flight parameters to the less restrictive ground parameters of the washout.
Motion of discrete solitons assisted by nonlinearity management.

PubMed

Cuevas, Jesús; Malomed, Boris A; Kevrekidis, P G

2005-06-01

We demonstrate that time-periodic modulation of the nonlinearity coefficient in the discrete nonlinear Schrödinger equation strongly facilitates creation of traveling solitons in the lattice. We predict this possibility in a semi-qualitative form analytically, and test it in direct numerical simulations. Systematic computations reveal several generic dynamical regimes, depending on the amplitude and frequency of the time modulation, and on the initial thrust which sets the soliton in motion. These regimes include irregular motion of the soliton, regular motion of a decaying one, and regular motion of a stable soliton. The motion may occur in both the straight and reverse directions, relative to the initial thrust. In the case of stable motion, extremely long simulations in a lattice with periodic boundary conditions demonstrate that the soliton keeps moving indefinitely long without any visible loss. Velocities of moving stable solitons are in good agreement with the analytical prediction, which is based on requiring a resonance between the ac drive and motion of the soliton through the periodic lattice. The generic dynamical regimes are mapped in the model's parameter space. Collisions between moving stable solitons are briefly investigated too, with a conclusion that two different outcomes are possible: elastic bounce, or bounce with mass transfer from one soliton to the other. The model can be realized experimentally in a Bose-Einstein condensate trapped in a deep optical lattice.
Immediate changes in widespread pressure pain sensitivity, neck pain, and cervical range of motion after cervical or thoracic thrust manipulation in patients with bilateral chronic mechanical neck pain: a randomized clinical trial.

PubMed

Martínez-Segura, Raquel; De-la-Llave-Rincón, Ana I; Ortega-Santiago, Ricardo; Cleland, Joshua A; Fernández-de-Las-Peñas, César

2012-09-01

Randomized clinical trial. To compare the effects of cervical versus thoracic thrust manipulation in patients with bilateral chronic mechanical neck pain on pressure pain sensitivity, neck pain, and cervical range of motion (CROM). Evidence suggests that spinal interventions can stimulate descending inhibitory pain pathways. To our knowledge, no study has investigated the neurophysiological effects of thoracic thrust manipulation in individuals with bilateral chronic mechanical neck pain, including widespread changes on pressure sensitivity. Ninety patients (51% female) were randomly assigned to 1 of 3 groups: cervical thrust manipulation on the right, cervical thrust manipulation on the left, or thoracic thrust manipulation. Pressure pain thresholds (PPTs) over the C5-6 zygapophyseal joint, lateral epicondyle, and tibialis anterior muscle, neck pain (11-point numeric pain rating scale), and cervical spine range of motion (CROM) were collected at baseline and 10 minutes after the intervention by an assessor blinded to the treatment allocation of the patients. Mixed-model analyses of covariance were used to examine the effects of the treatment on each outcome variable, with group as the between-subjects variable, time and side as the within-subject variables, and gender as the covariate. The primary analysis was the group-by-time interaction. No significant interactions were found with the mixed-model analyses of covariance for PPT level (C5-6, P>.210; lateral epicondyle, P>.186; tibialis anterior muscle, P>.268), neck pain intensity (P = .923), or CROM (flexion, P = .700; extension, P = .387; lateral flexion, P>.672; rotation, P>.192) as dependent variables. All groups exhibited similar changes in PPT, neck pain, and CROM (all, P<.001). Gender did not influence the main effects or the interaction effects in the analyses of the outcomes (P>.10). The results of the current randomized clinical trial suggest that cervical and thoracic thrust manipulation induce similar changes in PPT, neck pain intensity, and CROM in individuals with bilateral chronic mechanical neck pain. However, changes in PPT and CROM were small and did not surpass their respective minimal detectable change values. Further, because we did not include a control group, we cannot rule out a placebo effect of the thrust interventions on the outcomes. Therapy, level 1b.J Orthop Sports Phys Ther 2012;42(9):806-814, Epub 18 June 2012. doi:10.2519/jospt.2012.4151.
The Innovative Design and Prototype Verification of Wheelchair with One Degree of Freedom to Perform Lifting and Standing Functions

NASA Astrophysics Data System (ADS)

Hsieh, Long-Chang; Chen, Tzu-Hsia

2017-12-01

Traditionally, the mechanism of wheelchair with lifting and standing functions has 2 degrees of freedom, and used 2 power sources to perform these 2 motion function. The purpose of this paper is to invent new wheelchair with 1 degree of freedom to perform these 2 motion functions. Hence, we can use only 1 power source to drive the mechanism to achieve lifting and standing motion functions. The new design has the advantages of simple operation, more stability, and more safety. For traditional standing wheelchair, its’ centre of gravity moves forward when standing up and it needs 2 auxiliary wheels to prevent dumping. In this paper, by using the checklist method of Osborn, the wheelchair with 1 DOF is invented to perform lifting and standing functions. The centre of gravity of this new wheelchair after standing up still located between the front and rear wheels, no auxiliary wheels needed. Finally, the prototype is manufactured to verify the theoretical results.
Spacecraft formation control using analytical finite-duration approaches

NASA Astrophysics Data System (ADS)

Ben Larbi, Mohamed Khalil; Stoll, Enrico

2018-03-01

This paper derives a control concept for formation flight (FF) applications assuming circular reference orbits. The paper focuses on a general impulsive control concept for FF which is then extended to the more realistic case of non-impulsive thrust maneuvers. The control concept uses a description of the FF in relative orbital elements (ROE) instead of the classical Cartesian description since the ROE provide a direct insight into key aspects of the relative motion and are particularly suitable for relative orbit control purposes and collision avoidance analysis. Although Gauss' variational equations have been first derived to offer a mathematical tool for processing orbit perturbations, they are suitable for several different applications. If the perturbation acceleration is due to a control thrust, Gauss' variational equations show the effect of such a control thrust on the Keplerian orbital elements. Integrating the Gauss' variational equations offers a direct relation between velocity increments in the local vertical local horizontal frame and the subsequent change of Keplerian orbital elements. For proximity operations, these equations can be generalized from describing the motion of single spacecraft to the description of the relative motion of two spacecraft. This will be shown for impulsive and finite-duration maneuvers. Based on that, an analytical tool to estimate the error induced through impulsive maneuver planning is presented. The resulting control schemes are simple and effective and thus also suitable for on-board implementation. Simulations show that the proposed concept improves the timing of the thrust maneuver executions and thus reduces the residual error of the formation control.
Full scale hover test of a 25 foot tilt rotor

NASA Technical Reports Server (NTRS)

Helf, S.; Broman, E.; Gatchel, S.; Charles, B.

1973-01-01

The tilt rotor underwent a hover performance test on the Aero Propulsion Laboratory whirl stand at Wright-Patterson Air Force Base. The maximum thrust over density ratio measured at the design tip speed of 740 feet per second was 10,016 pounds. This occurred when the power over density ratio was 1721 horsepower. At the hover overspeed rpm, the thrust and power, over density ratio, were 11,008 pounds and 1866 horsepower. During the test, the maximum measured thrust coefficient was 0.177, and the rotor figure of merit exceeded 0.81. Measured lifting efficiency was 8.35 pounds per horsepower at the thrust a 13,000-pound aircraft would require for hover at sea level on a standard day. No effect of compressibility on performance is discernible in the test results (the range of tip Mach numbers tested was 0.55 to 0.71).
Green Propellant Test Capabilities of the Altitude Combustion Stand at the NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Kubiak, Jonathan M.; Arnett, Lori A.

2016-01-01

The NASA Glenn Research Center (GRC) is committed to providing simulated altitude rocket test capabilities to NASA programs, other government agencies, private industry partners, and academic partners. A primary facility to support those needs is the Altitude Combustion Stand (ACS). ACS provides the capability to test combustion components at a simulated altitude up to 100,000 ft. (approx.0.2 psia/10 Torr) through a nitrogen-driven ejector system. The facility is equipped with an axial thrust stand, gaseous and cryogenic liquid propellant feed systems, data acquisition system with up to 1000 Hz recording, and automated facility control system. Propellant capabilities include gaseous and liquid hydrogen, gaseous and liquid oxygen, and liquid methane. A water-cooled diffuser, exhaust spray cooling chamber, and multi-stage ejector systems can enable run times up to 180 seconds to 16 minutes. The system can accommodate engines up to 2000-lbf thrust, liquid propellant supply pressures up to 1800 psia, and test at the component level. Engines can also be fired at sea level if needed. The NASA GRC is in the process of modifying ACS capabilities to enable the testing of green propellant (GP) thrusters and components. Green propellants are actively being explored throughout government and industry as a non-toxic replacement to hydrazine monopropellants for applications such as reaction control systems or small spacecraft main propulsion systems. These propellants offer increased performance and cost savings over hydrazine. The modification of ACS is intended to enable testing of a wide range of green propellant engines for research and qualification-like testing applications. Once complete, ACS will have the capability to test green propellant engines up to 880 N in thrust, thermally condition the green propellants, provide test durations up to 60 minutes depending on thrust class, provide high speed control and data acquisition, as well as provide advanced imaging and diagnostics such as infrared (IR) imaging.
Experimental Results of Schlicher's Thrusting Antenna

NASA Technical Reports Server (NTRS)

Fralick, Gustave C.; Niedra, Janis M.

2001-01-01

Experiments were conducted to test the claims by Rex L. Schlicher, et al., (Patent 5,142,86 1) that a certain antenna geometry produces thrust greatly exceeding radiation reaction, when driven by repetitive, fast rise, and relatively slower decay current pulses. In order to test this hypothesis, the antenna was suspended by strings as a 3 in pendulum. Current pulses were fed to the antenna along the suspension path by a very flexible coaxial line constructed from loudspeaker cable and copper braid sheath. When driving the antenna via this cabling, our pulser was capable of sustaining 1200 A pulses at a rate of 30 per second up to a minute. In this way, bursts of pulses could be delivered in synch with the pendulum period in order to build up any motion. However, when using a laser beam passing through a lens attached to the antenna to amplify linear displacement by a factor of at least 25, no correlated motion of the beam spot could be detected on a distant wall. We conclude, in agreement with the momentum theorem of classical electromagnetic theory, that any thrust produced is far below practically useful levels. Hence, within classical electrodynamics, there is little hope of detecting any low level motion that cannot be explained by interactions with surrounding structural steel and the Earth's magnetic field.
Non-invasive 3D geometry extraction and robotic modeling of a Sea lion foreflipper

NASA Astrophysics Data System (ADS)

Patel, R. K.; Leftwich, M. C.; Friedman, C.

2016-02-01

California Sea Lions are very agile swimmers and unlike many marine animals, they use their fore flipper rather than their hind flipper undulations to generate high thrust values. To date there exist limited amount of qualitative studies for sea lions swimming that show the flippers are used for thrust, stability, and control during swimming motions. Quantitative studies mainly measured drag used for cost of transport, and analyzed banked turn performance. Recently, the kinematics of a California sea lion flipper during the thrust phase was extracted using video tracking in two dimensions. This work extends the tracking ability to three dimensions using a non-invasive Direct Linear Transformation (DLT) technique employed on non-research sea lions at the Smithsonian National Zoological Park. The flippers are therefore marker-less and tracking is carried out manually in post processing after capturing complete dorsal-ventral flipper motions. Two cameras are used (3840 × 2160 pixels resolution) and calibrated in space using a calibration target inserted into the sea lion habitat. They are synchronized in time using a simple light flash. The fluid flow and forces generated by a sea lion clap is also being explored. Recently, a sea lion flipper from a deceased subject was externally scanned in high detail for fluid dynamics research. The flipper's geometry is being used in this work to design and build an articulate flipper model that is approximately 60% of the full size span. The model is actuated by servo motors and is designed to mimic a sea lion flipper clap motion based on the previously extracted kinematics from above. The model incorporates three axles, simulating the movements of the sea lion's elbow, wrist, and knuckles. The flipper tip speed is designed to match typical Reynolds numbers for the full-scale flipper for an acceleration from rest maneuver. The model will be tested in a water flume to obtain the forces during the thrust production phase of the flipper motion.
Optimal Electrodynamic Tether Phasing Maneuvers

NASA Technical Reports Server (NTRS)

Bitzer, Matthew S.; Hall, Christopher D.

2007-01-01

We study the minimum-time orbit phasing maneuver problem for a constant-current electrodynamic tether (EDT). The EDT is assumed to be a point mass and the electromagnetic forces acting on the tether are always perpendicular to the local magnetic field. After deriving and non-dimensionalizing the equations of motion, the only input parameters become current and the phase angle. Solution examples, including initial Lagrange costates, time of flight, thrust plots, and thrust angle profiles, are given for a wide range of current magnitudes and phase angles. The two-dimensional cases presented use a non-tilted magnetic dipole model, and the solutions are compared to existing literature. We are able to compare similar trajectories for a constant thrust phasing maneuver and we find that the time of flight is longer for the constant thrust case with similar initial thrust values and phase angles. Full three-dimensional solutions, which use a titled magnetic dipole model, are also analyzed for orbits with small inclinations.
The effects of the stellar wind and orbital motion on the jets of high-mass microquasars

NASA Astrophysics Data System (ADS)

Bosch-Ramon, V.; Barkov, M. V.

2016-05-01

Context. High-mass microquasar jets propagate under the effect of the wind from the companion star, and the orbital motion of the binary system. The stellar wind and the orbit may be dominant factors determining the jet properties beyond the binary scales. Aims: This is an analytical study, performed to characterise the effects of the stellar wind and the orbital motion on the jet properties. Methods: Accounting for the wind thrust transferred to the jet, we derive analytical estimates to characterise the jet evolution under the impact of the stellar wind. We include the Coriolis force effect, induced by orbital motion and enhanced by the wind's presence. Large-scale evolution of the jet is sketched, accounting for wind-to-jet thrust transfer, total energy conservation, and wind-jet flow mixing. Results: If the angle of the wind-induced jet bending is larger than its half-opening angle, the following is expected: (I) a strong recollimation shock; (II) bending against orbital motion, caused by Coriolis forces and enhanced by the wind presence; and (III) non-ballistic helical propagation further away. Even if disrupted, the jet can re-accelerate due to ambient pressure gradients, but wind entrainment can weaken this acceleration. On large scales, the opening angle of the helical structure is determined by the wind-jet thrust relation, and the wind-loaded jet flow can be rather slow. Conclusions: The impact of stellar winds on high-mass microquasar jets can yield non-ballistic helical jet trajectories, jet partial disruption and wind mixing, shocks, and possibly non-thermal emission. Among other observational diagnostics, such as radiation variability at any band, the radio morphology on milliarcsecond scales can be informative on the wind-jet interaction.
Effect of spine motion on mobility in quadruped running

NASA Astrophysics Data System (ADS)

Chen, Dongliang; Liu, Qi; Dong, Litao; Wang, Hong; Zhang, Qun

2014-11-01

Most of current running quadruped robots have similar construction: a stiff body and four compliant legs. Many researches have indicated that the stiff body without spine motion is a main factor in limitation of robots' mobility. Therefore, investigating spine motion is very important to build robots with better mobility. A planar quadruped robot is designed based on cheetahs' morphology. There is a spinal driving joint in the body of the robot. When the spinal driving joint acts, the robot has spine motion; otherwise, the robot has not spine motion. Six group prototype experiments with the robot are carried out to study the effect of spine motion on mobility. In each group, there are two comparative experiments: the spinal driving joint acts in one experiment but does not in the other experiment. The results of the prototype experiments indicate that the average speeds of the robot with spine motion are 8.7%-15.9% larger than those of the robot without spine motion. Furthermore, a simplified sagittal plane model of quadruped mammals is introduced. The simplified model also has a spinal driving joint. Using a similar process as the prototype experiments, six group simulation experiments with the simplified model are conducted. The results of the simulation experiments show that the maximum rear leg horizontal thrusts of the simplified mode with spine motion are 68.2%-71.3% larger than those of the simplified mode without spine motion. Hence, it is found that spine motion can increase the average running speed and the intrinsic reason of speed increase is the improvement of the maximum rear leg horizontal thrust.
Laser-heated thruster

NASA Technical Reports Server (NTRS)

Kemp, N. H.; Krech, R. H.

1980-01-01

The development of computer codes for the thrust chamber of a rocket of which the propellant gas is heated by a CW laser beam was investigated. The following results are presented: (1) simplified models of laser heated thrusters for approximate parametric studies and performance mapping; (3) computer programs for thrust chamber design; and (3) shock tube experiment to measure absorption coefficients. Two thrust chamber design programs are outlined: (1) for seeded hydrogen, with both low temperature and high temperature seeds, which absorbs the laser radiation continuously, starting at the inlet gas temperature; and (2) for hydrogen seeded with cesium, in which a laser supported combustion wave stands near the gas inlet, and heats the gas up to a temperature at which the gas can absorb the laser energy.
A Method for Integrating Thrust-Vectoring and Actuated Forebody Strakes with Conventional Aerodynamic Controls on a High-Performance Fighter Airplane

NASA Technical Reports Server (NTRS)

Lallman, Frederick J.; Davidson, John B.; Murphy, Patrick C.

1998-01-01

A method, called pseudo controls, of integrating several airplane controls to achieve cooperative operation is presented. The method eliminates conflicting control motions, minimizes the number of feedback control gains, and reduces the complication of feedback gain schedules. The method is applied to the lateral/directional controls of a modified high-performance airplane. The airplane has a conventional set of aerodynamic controls, an experimental set of thrust-vectoring controls, and an experimental set of actuated forebody strakes. The experimental controls give the airplane additional control power for enhanced stability and maneuvering capabilities while flying over an expanded envelope, especially at high angles of attack. The flight controls are scheduled to generate independent body-axis control moments. These control moments are coordinated to produce stability-axis angular accelerations. Inertial coupling moments are compensated. Thrust-vectoring controls are engaged according to their effectiveness relative to that of the aerodynamic controls. Vane-relief logic removes steady and slowly varying commands from the thrust-vectoring controls to alleviate heating of the thrust turning devices. The actuated forebody strakes are engaged at high angles of attack. This report presents the forward-loop elements of a flight control system that positions the flight controls according to the desired stability-axis accelerations. This report does not include the generation of the required angular acceleration commands by means of pilot controls or the feedback of sensed airplane motions.
Saturn Apollo Program

NASA Image and Video Library

1963-12-05

The test laboratory of the Marshall Space Flight Center (MSFC) tested the F-1 engine, the most powerful rocket engine ever fired at MSFC. The engine was tested on the newly modified Saturn IB Static Test Stand which had been used for three years to test the Saturn I eight-engine booster, S-I (first) stage. In 1961 the test stand was modified to permit static firing of the S-I/S-IB stage and the name of the stand was then changed to the S-IB Static Test Stand. Producing a combined thrust of 7,500,000 pounds, five F-1 engines powered the S-IC (first) stage of the Saturn V vehicle for the marned lunar mission.
Saturn Apollo Program

NASA Image and Video Library

1963-12-01

The test laboratory of the Marshall Space Flight Center (MSFC) tested the F-1 engine, the most powerful rocket engine ever fired at MSFC. The engine was tested on the newly modified Saturn IB static test stand that had been used for three years to test the Saturn I eight-engine booster, S-I (first) stage. In 1961, the test stand was modified to permit static firing of the S-I/S-IB stage and the name of the stand was then changed to the S-IB Static Test Stand. Producing a combined thrust of 7,500,000 pounds, five F-1 engines powered the S-IC (first) stage of the Saturn V vehicle for the marned lunar mission.
Thrusting Rates in the Early Eocene from the Sevier Hinterland, Idaho, USA

NASA Astrophysics Data System (ADS)

Anastasio, D. J.; Latta, D.; Kodama, K. P.; Idleman, B. D.

2011-12-01

The terminal motion on the Wildhorse thrust system was reconstructed from the Smiley Creek Formation in eastern Idaho, USA (UTM coordinates 11T 739950 m E, 4865190 m N). During the last 100 m of fault slip the calculated slip rate varied between 0.05 to 1.2 mm/yr averaged over time intervals of 300-800 kyrs. The emergent thrust fault overrode proximal fault scarp colluvium deposited as water poor debris flows and was buried by braided stream sheet flood facies sourced by out-of-sequence thrust motion further west. Paleomagnetic data (~100 cores from 27 horizons spaced ~5-60 m apart) showed both normal and reversed directions during progressive step-wise thermal demagnetization to 670° C. Principal component analysis was used to calculate characteristic remanent magnetization directions from which sample polarities were assigned. Correlation of the Smiley Creek Formation to the Geomagnetic Polarity Timescale requires an age older than 49.39±0.27 (n=7) Ma determined by 40Ar/39Ar dating of overlying Challis Volcanic samples and younger than 57±9 Ma, the youngest U/Pb zircon age from an included andesite cobble from a near by Smiley Creek conglomerate exposure (11T 766548 m E, 4874382 m N). The favored magnetostratigraphic correlation is most consistent with expected terrestrial fan facies accumulation rates, the reversal pattern, and calculated paleopole positions. The 183 m of Smiley Creek Formation west of Stag Creek, Idaho was deposited in 4.48 myrs during polarity chrons 24.3n to 23n2n. The terminal emplacement of the Wildhorse thrust was associated with the development of the Pioneer Metamorphic Core complex in the hinterland of the Montana Recess of the Idaho-Wyoming-Montana thrust belt.

Spinning Rocket Simulator Turntable Design

NASA Technical Reports Server (NTRS)

Miles, Robert W.

2001-01-01

Contained herein is the research and data acquired from the Turntable Design portion of the Spinning Rocket Simulator (SRS) project. The SRS Project studies and eliminates the effect of coning on thrust-propelled spacecraft. This design and construction of the turntable adds a structural support for the SRS model and two degrees of freedom. The two degrees of freedom, radial and circumferential, will help develop a simulated thrust force perpendicular to the plane of the spacecraft model while undergoing an unstable coning motion. The Turntable consists of a ten-foot linear track mounted to a sprocket and press-fit to a thrust bearing. A two-inch high column grounded by a Triangular Baseplate supports this bearing and houses the slip rings and pressurized, air-line swivel. The thrust bearing allows the entire system to rotate under the moment applied through the chain-driven sprocket producing a circumferential degree of freedom. The radial degree of freedom is given to the model through the helically threaded linear track. This track allows the Model Support and Counter Balance to simultaneously reposition according to the coning motion of the Model. Two design factors that hinder the linear track are bending and twist due to torsion. A Standard Aluminum "C" channel significantly reduces these two deflections. Safety considerations dictate the design of all the components involved in this project.
One microplate - three orogens: Alps, Dinarides, Apennines and the role of the Adriatic plate

NASA Astrophysics Data System (ADS)

Ustaszewski, Kamil; Le Breton, Eline; Balling, Philipp; Handy, Mark R.; Molli, Giancarlo; Tomljenović, Bruno

2017-04-01

The motion of the Adriatic microplate with respect to the Eurasian and African plates is responsible for the Mesozoic to present tectonic evolution of the Alps, Carpathians, the Dinarides and Hellenides as well as the Apennines. The classical approach for reconstructing plate motions is to assume that tectonic plates are rigid, then apply Euler's theorem to describe their rotation on an ideally spherical Earth by stepwise restorations of magnetic anomalies and fracture zones in oceanic basins. However, this approach is inadequate for reconstructing the motion of Mediterranean microplates like Adria, which, at present, is surrounded by convergent margins and whose oceanic portions have by now been entirely subducted. Most constraints on the motion of the Adriatic microplate come either from palaeomagnetics or from shortening estimates in the Alps, i.e., its northern margin. This approach renders plate tectonic reconstructions prone to numerous errors, yielding inadmissible misfits in the Ionian Sea between southern Italy and northern Greece. At the same time, Adria's western and eastern margins in the Apennines and in the Dinarides have hitherto not been appropriately considered for improving constraints on the motion of Adria. This presentation presents new results of ongoing collaborative research that aims at improving the relative motion path for the Adriatic microplate for the Cenozoic by additionally quantifying and restoring the amount of shortening and extension in a set of geophysical-geological transects from the Tyrrhenian Sea, the Apennines and the Dinarides. Already now, our approach yields an improved motion path for the Adriatic microplate for the last 20 Ma, which minimizes misfits in previous reconstructions. The currently largest challenge in our reconstructions is to reconcile amount and age of shortening in the Dinarides fold-and-thrust belt. For one thing, we see good agreement between the cross-sectional length of subducted material (c. 135 km, estimated from p-wave tomographic models) and shortening in the external carbonate platform of the Dinarides thrust belt (c. 127 km, from balanced cross sections). However, most of the thrust belt shortening is of Palaeogene age, which is difficult to bring into agreement with the fact that most of the subduction observed in tomographic models is most likely of Neogene age. This suggests that a substantial amount of Neogene crustal shortening must have been accommodated in the internal parts of the Dinarides fold-and-thrust belt rather than along its front. More field studies are therefore badly needed to obtain a better understanding of the timing of individual faults and their role during the Neogene evolution of the NE margin of the Adriatic plate.
ASCENT Program

NASA Technical Reports Server (NTRS)

Brown, Richard; Collier, Gary; Heckenlaible, Richard; Dougherty, Edward; Dolenz, James; Ross, Iain

2012-01-01

The ASCENT program solves the three-dimensional motion and attendant structural loading on a flexible vehicle incorporating, optionally, an active analog thrust control system, aerodynamic effects, and staging of multiple bodies. ASCENT solves the technical problems of loads, accelerations, and displacements of a flexible vehicle; staging of the upper stage from the lower stage; effects of thrust oscillations on the vehicle; a payload's relative motion; the effect of fluid sloshing on vehicle; and the effect of winds and gusts on the vehicle (on the ground or aloft) in a continuous analysis. The ATTACH ASCENT Loads program reads output from the ASCENT flexible body loads program, and calculates the approximate load indicators for the time interval under consideration. It calculates the load indicator values from pre-launch to the end of the first stage.
A guidance and navigation system for continuous low-thrust vehicles. M.S. Thesis

NASA Technical Reports Server (NTRS)

Jack-Chingtse, C.

1973-01-01

A midcourse guidance and navigation system for continuous low thrust vehicles was developed. The equinoctial elements are the state variables. Uncertainties are modelled statistically by random vector and stochastic processes. The motion of the vehicle and the measurements are described by nonlinear stochastic differential and difference equations respectively. A minimum time trajectory is defined; equations of motion and measurements are linearized about this trajectory. An exponential cost criterion is constructed and a linear feedback quidance law is derived. An extended Kalman filter is used for state estimation. A short mission using this system is simulated. It is indicated that this system is efficient for short missions, but longer missions require accurate trajectory and ground based measurements.
Propeller propulsion integration, phase 1. [conducted in langley 30 by 60 foot full scale wind tunnel

NASA Technical Reports Server (NTRS)

Bennett, G.; Koenig, K.; Miley, S. J.; Mcwhorter, J.; Wells, G.

1981-01-01

A bibliography was compiled of all readily available sources of propeller analytical and experimental studies conducted during the 1930 through 1960 period. A propeller test stand was developed for the measurement of thrust and torque characteristics of full scale general aviation propellers and installed in the LaRC 30 x 60 foot full scale wind tunnel. A tunnel entry was made during the January through February 1980 period. Several propellers were tested, but unforseen difficulties with the shaft thrust torque balance severely degraded the data quality.
Research Technology

NASA Image and Video Library

1998-09-16

A team of engineers at Marshall Space Flight Center (MSFC) has designed, fabricated, and tested the first solar thermal engine, a non-chemical rocket that produces lower thrust but has better thrust efficiency than the chemical combustion engines. This segmented array of mirrors is the solar concentrator test stand at MSFC for firing the thermal propulsion engines. The 144 mirrors are combined to form an 18-foot diameter array concentrator. The mirror segments are aluminum hexagons that have the reflective surface cut into it by a diamond turning machine, which is developed by MSFC Space Optics Manufacturing Technology Center.
Role of the Kazerun fault system in active deformation of the Zagros fold-and-thrust belt (Iran)

NASA Astrophysics Data System (ADS)

Authemayou, Christine; Bellier, Olivier; Chardon, Dominique; Malekzade, Zaman; Abassi, Mohammad

2005-04-01

Field structural and SPOT image analyses document the kinematic framework enhancing transfer of strike-slip partitioned motion from along the backstop to the interior of the Zagros fold-and-thrust belt in a context of plate convergence slight obliquity. Transfer occurs by slip on the north-trending right-lateral Kazerun Fault System (KFS) that connects to the Main Recent Fault, a major northwest-trending dextral fault partitioning oblique convergence at the rear of the belt. The KFS formed by three fault zones ended by bent orogen-parallel thrusts allows slip from along the Main Recent Fault to become distributed by transfer to longitudinal thrusts and folds. To cite this article: C. Authemayou et al., C. R. Geoscience 337 (2005).
Around Marshall

NASA Image and Video Library

1962-07-03

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of July 3, 1963. All four of its tower legs are well underway.
Around Marshall

NASA Image and Video Library

1963-09-05

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of September 5, 1963.
n/a

NASA Image and Video Library

1962-10-26

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC test stand, related facilities were built during this time. Built to the north of the massive S-IC test stand, was the F-1 Engine test stand. The F-1 test stand, a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken October 26, 1962, depicts the excavation process of the single engine F-1 stand.
Around Marshall

NASA Image and Video Library

1963-09-30

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of September 30, 1963.
Around Marshall

NASA Image and Video Library

1963-06-24

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of June 24, 1963. Two if its four tower legs are underway.
n/a

NASA Image and Video Library

1962-11-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC test stand, related facilities were built during this time. Built to the north of the massive S-IC test stand, was the F-1 Engine test stand. The F-1 test stand, a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken November 15, 1962, depicts the excavation process of the single engine F-1 stand site.
Around Marshall

NASA Image and Video Library

1963-10-22

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Northeast of the massive S-IC test stand, the F-1 Engine test stand was built. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the fuel tanks that housed kerosene and just beyond those is the F-1 test stand.
Plate Motion and Crustal Deformation Estimated with Geodetic Data from the Global Positioning System

NASA Technical Reports Server (NTRS)

Argus, Donald F.; Heflin, Michael B.

1995-01-01

We use geodetic data taken over four years with the Global Positioning System (GPS) to estimate: (1) motion between six major plates and (2) motion relative to these plates of ten sites in plate boundary zones. The degree of consistency between geodetic velocities and rigid plates requires the (one-dimensional) standard errors in horizontal velocities to be approx. 2 mm/yr. Each of the 15 angular velocities describing motion between plate pairs that we estimate with GPS differs insignificantly from the corresponding angular velocity in global plate motion model NUVEL-1A, which averages motion over the past 3 m.y. The motion of the Pacific plate relative to both the Eurasian and North American plates is observed to be faster than predicted by NUVEL-1A, supporting the inference from Very Long B ase- line Interferometry (VLBI) that motion of the Pacific plate has speed up over the past few m.y. The Eurasia-North America pole of rotation is estimated to be north of NUVEL-1A, consistent with the independent hypothesis that the pole has recently migrated northward across northeast Asia to near the Lena River delta. Victoria, which lies above the main thrust at the Cascadia subduction zone, moves relative to the interior of the overriding plate at 30% of the velocity of the subducting plate, reinforcing the conclusion that the thrust there is locked beneath the continental shelf and slope.
Saturn Apollo Program

NASA Image and Video Library

1967-07-28

This photograph depicts a view of the test firing of all five F-1 engines for the Saturn V S-IC test stage at the Marshall Space Flight Center. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon. Operating at maximum power, all five of the engines produced 7,500,000 pounds of thrust. The S-IC Static Test Stand was designed and constructed with the strength of hundreds of tons of steel and cement, planted down to bedrock 40 feet below ground level, and was required to hold down the brute force of the 7,500,000-pound thrust. The structure was topped by a crane with a 135-foot boom. With the boom in the up position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. When the Saturn V S-IC first stage was placed upright in the stand , the five F-1 engine nozzles pointed downward on a 1,900-ton, water-cooled deflector. To prevent melting damage, water was sprayed through small holes in the deflector at the rate 320,000 gallons per minutes
Saturn Apollo Program

NASA Image and Video Library

1965-05-01

This photograph depicts a view of the test firing of all five F-1 engines for the Saturn V S-IC test stage at the Marshall Space Flight Center. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon. Operating at maximum power, all five of the engines produced 7,500,000 pounds of thrust. The S-IC Static Test Stand was designed and constructed with the strength of hundreds of tons of steel and cement, planted down to bedrock 40 feet below ground level, and was required to hold down the brute force of the 7,500,000-pound thrust. The structure was topped by a crane with a 135-foot boom. With the boom in the up position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. When the Saturn V S-IC first stage was placed upright in the stand , the five F-1 engine nozzles pointed downward on a 1,900-ton, water-cooled deflector. To prevent melting damage, water was sprayed through small holes in the deflector at the rate 320,000 gallons per minutes.
Optimal orbit transfer suitable for large flexible structures

NASA Technical Reports Server (NTRS)

Chatterjee, Alok K.

1989-01-01

The problem of continuous low-thrust planar orbit transfer of large flexible structures is formulated as an optimal control problem with terminal state constraints. The dynamics of the spacecraft motion are treated as a point-mass central force field problem; the thrust-acceleration magnitude is treated as an additional state variable; and the rate of change of thrust-acceleration is treated as a control variable. To ensure smooth transfer, essential for flexible structures, an additional quadratic term is appended to the time cost functional. This term penalizes any abrupt change in acceleration. Numerical results are presented for the special case of a planar transfer.
Project NEO Specific Impulse Testing Solutions

NASA Technical Reports Server (NTRS)

Baffa, Bill

2018-01-01

The Neo test stand is currently configured to fire a horizontally mounted rocket motor with up to 6500 lbf thrust. Currently, the Neo test stand can measure flow of liquid propellant and oxidizer, pressures residing in the closed system up to the combustion chamber. The current configuration does not have the ability to provide all data needed to compute specific impulse. This presents three methods to outfit the NEO test fixture with instrumentation allowing for calculation of specific impulse.
Saturn Apollo Program

NASA Image and Video Library

1965-04-16

This photograph depicts a dramatic view of the first test firing of all five F-1 engines for the Saturn V S-IC stage at the Marshall Space Flight Center. The testing lasted a full duration of 6.5 seconds. It also marked the first test performed in the new S-IC static test stand and the first test using the new control blockhouse. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon. Operating at maximum power, all five of the engines produced 7,500,000 pounds of thrust. Required to hold down the brute force of a 7,500,000-pound thrust, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and cement, planted down to bedrock 40 feet below ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the up position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. When the Saturn V S-IC first stage was placed upright in the stand , the five F-1 engine nozzles pointed downward on a 1,900 ton, water-cooled deflector. To prevent melting damage, water was sprayed through small holes in the deflector at the rate 320,000 gallons per minute.

Behavioral effect of knee joint motion on body's center of mass during human quiet standing.

PubMed

Yamamoto, Akio; Sasagawa, Shun; Oba, Naoko; Nakazawa, Kimitaka

2015-01-01

The balance control mechanism during upright standing has often been investigated using single- or double-link inverted pendulum models, involving the ankle joint only or both the ankle and hip joints, respectively. Several studies, however, have reported that knee joint motion during quiet standing cannot be ignored. This study aimed to investigate the degree to which knee joint motion contributes to the center of mass (COM) kinematics during quiet standing. Eight healthy adults were asked to stand quietly for 30s on a force platform. Angular displacements and accelerations of the ankle, knee, and hip joints were calculated from kinematic data obtained by a motion capture system. We found that the amplitude of the angular acceleration was smallest in the ankle joint and largest in the hip joint (ankle < knee < hip). These angular accelerations were then substituted into three biomechanical models with or without the knee joint to estimate COM acceleration in the anterior-posterior direction. Although the "without-knee" models greatly overestimated the COM acceleration, the COM acceleration estimated by the "with-knee" model was similar to the actual acceleration obtained from force platform measurement. These results indicate substantial effects of knee joint motion on the COM kinematics during quiet standing. We suggest that investigations based on the multi-joint model, including the knee joint, are required to reveal the physiologically plausible balance control mechanism implemented by the central nervous system. Copyright © 2014 Elsevier B.V. All rights reserved.
Space Shuttle Projects

NASA Image and Video Library

1979-07-13

This is a photograph of the solid rocket booster's (SRB's) Qualification Motor-1 (QM-1) being prepared for a static firing in a test stand at the Morton Thiokol Test Site in Wasatch, Utah, showing the aft end of the booster. The twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. Under the direction of the Marshall Space Flight Center, the SRM's are provided by the Morton Thiokol Corporation.
Unsteady lift and thrust of a 2D flapping thin airfoil in the presence of additional leading edge vortices

NASA Astrophysics Data System (ADS)

Alaminos-Quesada, Javier; Fernandez-Feria, Ramon

2017-11-01

The effect of leading-edge vortices (LEVs) on the lift, thrust and moment of a two-dimensional heaving and pitching foil is analyzed from the unsteady, linear potential theory. General expressions taking into account the effect of unsteady point vortices interacting with the oscillatory trailing wake are first derived. Then, simplified expressions for the initial stages of the growing LEV on each half-stroke are used to obtain analytical closed expressions for the main contribution of these vortices to the lift, thrust and moment. It is found that, within the linear potential framework and the Brown-Michael model, the LEV contributes to the aerodynamic forces and moment only for combined pitching and heaving motions of the foil, being a relevant contribution for sufficiently large values of the product of the reduced frequency and the amplitude of the heaving and/or pitching motions. The results are compared with available experimental data and numerical simulations. Supported by the Ministerio de Economia y Competitividad of Spain Grants No. DPI2013-40479-P and DPI2016-76151-C2-1-R.
A study of sea lion hydrodynamics using a robotic foreflipper platform

NASA Astrophysics Data System (ADS)

Kulkarni, Aditya A.; Patel, Rahi K.; Leftwich, Megan C.

2016-11-01

Unlike most fish and mammals-that utilize BCF swimming-sea lions rely on their foreflippers to generate thrust without a characteristic flapping frequency. This unique swimming style allows the sea lion to be highly maneuverable, while also producing high amounts of thrust. To explore this motion, and the physics that underlies it, we use novel markerless tracking techniques on untrained sea lions at the Smithsonian National Zoo in Washington, D.C to get the complete motion during different maneuvers. High speed video and three-dimensional surface reconstruction techniques are used to extract the foreflippers kinematics during the thrust phase. Using this data, pitch angle is calculated with respect to the base of the flipper to build a scaled robotic flipper. Dye visualization is carried out in a water channel by injecting dye upstream of the leading edge of the flipper with flow speed set to explore different parameters, like Reynolds number or angular velocity. Results show low pressure on the upper surface of the flipper causes the fluid to be pulled around the flipper forming a vortex that moves fully out of the plane.
Around Marshall

NASA Image and Video Library

1963-11-20

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo shows the progress of the F-1 Test Stand as of November 20, 1963.
Around Marshall

NASA Image and Video Library

1963-04-04

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken April 4, 1963 depicts the construction of the F-1 test stand foundation walls.
Around Marshall

NASA Image and Video Library

1963-04-17

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken April 17, 1963 depicts the construction of the F-1 test stand foundation walls.
Structure and regional significance of the Late Permian(?) Sierra Nevada - Death Valley thrust system, east-central California

USGS Publications Warehouse

Stevens, C.H.; Stone, P.

2005-01-01

An imbricate system of north-trending, east-directed thrust faults of late Early Permian to middle Early Triassic (most likely Late Permian) age forms a belt in east-central California extending from the Mount Morrison roof pendant in the eastern Sierra Nevada to Death Valley. Six major thrust faults typically with a spacing of 15-20 km, original dips probably of 25-35??, and stratigraphic throws of 2-5 km compose this structural belt, which we call the Sierra Nevada-Death Valley thrust system. These thrusts presumably merge into a de??collement at depth, perhaps at the contact with crystalline basement, the position of which is unknown. We interpret the deformation that produced these thrusts to have been related to the initiation of convergent plate motion along a southeast-trending continental margin segment probably formed by Pennsylvanian transform truncation. This deformation apparently represents a period of tectonic transition to full-scale convergence and arc magmatism along the continental margin beginning in the Late Triassic in central California. ?? 2005 Elsevier B.V. All rights reserved.
Flapping Tail Membrane in Bats Produces Potentially Important Thrust during Horizontal Takeoffs and Very Slow Flight

PubMed Central

Adams, Rick A.; Snode, Emily R.; Shaw, Jason B.

2012-01-01

Historically, studies concerning bat flight have focused primarily on the wings. By analyzing high-speed video taken on 48 individuals of five species of vespertilionid bats, we show that the capacity to flap the tail-membrane (uropatagium) in order to generate thrust and lift during takeoffs and minimal-speed flight (<1 m s−1) was largely underestimated. Indeed, bats flapped the tail-membrane by extensive dorso-ventral fanning motions covering as much as 135 degrees of arc consistent with thrust generation by air displacement. The degree of dorsal extension of the tail-membrane, and thus the potential amount of thrust generated during platform launches, was significantly correlated with body mass (P = 0.02). Adduction of the hind limbs during upstrokes collapsed the tail-membrane thereby reducing its surface area and minimizing negative lift forces. Abduction of the hind limbs during the downstroke fully expanded the tail-membrane as it was swept ventrally. The flapping kinematics of the tail-membrane is thus consistent with expectations for an airfoil. Timing offsets between the wings and tail-membrane during downstrokes was as much as 50%, suggesting that the tail-membrane was providing thrust and perhaps lift when the wings were retracting through the upstoke phase of the wing-beat cycle. The extent to which the tail-membrane was used during takeoffs differed significantly among four vespertilionid species (P = 0.01) and aligned with predictions derived from bat ecomorphology. The extensive fanning motion of the tail membrane by vespertilionid bats has not been reported for other flying vertebrates. PMID:22393378
Large-Scale Wind-Tunnel Tests of Exhaust Ingestion Due to Thrust Reversal on a Four-Engine Jet Transport during Ground Roll

NASA Technical Reports Server (NTRS)

Tolhurst, William H., Jr.; Hickey, David H.; Aoyagi, Kiyoshi

1961-01-01

Wind-tunnel tests have been conducted on a large-scale model of a swept-wing jet transport type airplane to study the factors affecting exhaust gas ingestion into the engine inlets when thrust reversal is used during ground roll. The model was equipped with four small jet engines mounted in nacelles beneath the wing. The tests included studies of both cascade and target type reversers. The data obtained included the free-stream velocity at the occurrence of exhaust gas ingestion in the outboard engine and the increment of drag due to thrust reversal for various modifications of thrust reverser configuration. Motion picture films of smoke flow studies were also obtained to supplement the data. The results show that the free-stream velocity at which ingestion occurred in the outboard engines could be reduced considerably, by simple modifications to the reversers, without reducing the effective drag due to reversed thrust.
Navy and the HARV: High angle of attack tactical utility issues

NASA Technical Reports Server (NTRS)

Sternberg, Charles A.; Traven, Ricardo; Lackey, James B.

1994-01-01

This presentation will highlight results from the latest Navy evaluation of the HARV (March 1994) and focus primarily on the impressions from a piloting standpoint of the tactical utility of thrust vectoring. Issue to be addressed will be mission suitability of high AOA flight, visual and motion feedback cues associated with operating at high AOA, and the adaptability of a pilot to effectively use the increased control power provided by the thrust vectoring system.
The immediate effects of manual stretching and cervicothoracic junction manipulation on cervical range of motion and upper trapezius pressure pain thresholds.

PubMed

Hanney, William J; Puentedura, Emilio J; Kolber, Morey J; Liu, Xinliang; Pabian, Patrick S; Cheatham, Scott W

2017-09-22

Myofascial pain is a common impairment treated with various manual interventions including spinal thrust manipulation and stretching; however, the comparative efficacy of each intervention is uncertain. Therefore, the purpose of this investigation was to evaluate thrust manipulation targeting the cervicothoracic junction compared to a manual stretch of the upper trapezius muscle on cervical range of motion and upper trapezius pressure pain thresholds (PPTs). Healthy participants with no significant history of neck pain were randomized into a thrust manipulation group, a stretching group, or a control group. Within group differences were evaluated via a dependent t-test, and group by time interactions were evaluated by a two-way repeated measures ANOVA. One hundred and two participants were recruited to participate. Baseline demographics revealed no significant differences between groups. Significant group by time interactions were found for changes in PPTs for both the right and left upper trapezius. Also, significant differences were found for changes in cervical extension, as well as right and left cervical side bending favoring the treatment groups. This study demonstrates the potential independent effectiveness of spinal thrust manipulation or stretching for reducing PPTs at the upper trapezius. Future research should further evaluate the limitation of PPTs as a measure of muscle sensitivity as well as factors that may contribute to variability in the measurements among individuals seeking care.
Head-bobbing behavior in foraging Whooping Cranes

USGS Publications Warehouse

Cronin, T.; Kinloch, M.; Olsen, Glenn H.

2006-01-01

Many species of cursorial birds 'head-bob', that is, they alternately thrust the head forward, then hold it stiII as they walk. Such a motion stabilizes visual fields intermittently and could be critical for visual search; yet the time available for stabilization vs. forward thrust varies with walking speed. Whooping Cranes (Grus americana) are extremely tall birds that visually search the ground for seeds, berries, and small prey. We examined head movements in unrestrained Whooping Cranes using digital video subsequently analyzed with a computer graphical overlay. When foraging, the cranes walk at speeds that allow the head to be held still for at least 50% of the time. This behavior is thought to balance the two needs for covering as much ground as possible and for maximizing the time for visual fixation of the ground in the search for prey. Our results strongly suggest that in cranes, and probably many other bird species, visual fixation of the ground is required for object detection and identification. The thrust phase of the head-bobbing cycle is probably also important for vision. As the head moves forward, the movement generates visual flow and motion parallax, providing visual cues for distances and the relative locations of objects. The eyes commonly change their point of fixation when the head is moving too, suggesting that they remain visually competent throughout the entire cycle of thrust and stabilization.
Beam efflux measurements

NASA Technical Reports Server (NTRS)

Komatsu, G. K.; Stellen, J. M., Jr.

1976-01-01

Measurements have been made of the high energy thrust ions, (Group I), high angle/high energy ions (Group II), and high angle/low energy ions (Group IV) of a mercury electron bombardment thruster in the angular divergence range from 0 deg to greater than 90 deg. The measurements have been made as a function of thrust ion current, propellant utilization efficiency, bombardment discharge voltage, screen and accelerator grid potential (accel-decel ratio) and neutralizer keeper potential. The shape of the Group IV (charge exchange) ion plume has remained essentially fixed within the range of variation of the engine operation parameters. The magnitude of the charge exchange ion flux scales with thrust ion current, for good propellant utilization conditions. For fixed thrust ion current, charge exchange ion flux increases for diminishing propellant utilization efficiency. Facility effects influence experimental accuracies within the range of propellant utilization efficiency used in the experiments. The flux of high angle/high energy Group II ions is significantly diminished by the use of minimum decel voltages on the accelerator grid. A computer model of charge exchange ion production and motion has been developed. The program allows computation of charge exchange ion volume production rate, total production rate, and charge exchange ion trajectories for "genuine" and "facilities effects" particles. In the computed flux deposition patterns, the Group I and Group IV ion plumes exhibit a counter motion.
A Novel Method for Vertical Acceleration Noise Suppression of a Thrust-Vectored VTOL UAV.

PubMed

Li, Huanyu; Wu, Linfeng; Li, Yingjie; Li, Chunwen; Li, Hangyu

2016-12-02

Acceleration is of great importance in motion control for unmanned aerial vehicles (UAVs), especially during the takeoff and landing stages. However, the measured acceleration is inevitably polluted by severe noise. Therefore, a proper noise suppression procedure is required. This paper presents a novel method to reduce the noise in the measured vertical acceleration for a thrust-vectored tail-sitter vertical takeoff and landing (VTOL) UAV. In the new procedure, a Kalman filter is first applied to estimate the UAV mass by using the information in the vertical thrust and measured acceleration. The UAV mass is then used to compute an estimate of UAV vertical acceleration. The estimated acceleration is finally fused with the measured acceleration to obtain the minimum variance estimate of vertical acceleration. By doing this, the new approach incorporates the thrust information into the acceleration estimate. The method is applied to the data measured in a VTOL UAV takeoff experiment. Two other denoising approaches developed by former researchers are also tested for comparison. The results demonstrate that the new method is able to suppress the acceleration noise substantially. It also maintains the real-time performance in the final estimated acceleration, which is not seen in the former denoising approaches. The acceleration treated with the new method can be readily used in the motion control applications for UAVs to achieve improved accuracy.
A Novel Method for Vertical Acceleration Noise Suppression of a Thrust-Vectored VTOL UAV

PubMed Central

Li, Huanyu; Wu, Linfeng; Li, Yingjie; Li, Chunwen; Li, Hangyu

2016-01-01

Acceleration is of great importance in motion control for unmanned aerial vehicles (UAVs), especially during the takeoff and landing stages. However, the measured acceleration is inevitably polluted by severe noise. Therefore, a proper noise suppression procedure is required. This paper presents a novel method to reduce the noise in the measured vertical acceleration for a thrust-vectored tail-sitter vertical takeoff and landing (VTOL) UAV. In the new procedure, a Kalman filter is first applied to estimate the UAV mass by using the information in the vertical thrust and measured acceleration. The UAV mass is then used to compute an estimate of UAV vertical acceleration. The estimated acceleration is finally fused with the measured acceleration to obtain the minimum variance estimate of vertical acceleration. By doing this, the new approach incorporates the thrust information into the acceleration estimate. The method is applied to the data measured in a VTOL UAV takeoff experiment. Two other denoising approaches developed by former researchers are also tested for comparison. The results demonstrate that the new method is able to suppress the acceleration noise substantially. It also maintains the real-time performance in the final estimated acceleration, which is not seen in the former denoising approaches. The acceleration treated with the new method can be readily used in the motion control applications for UAVs to achieve improved accuracy. PMID:27918422
Saturn Apollo Program

NASA Image and Video Library

1964-12-01

At the Marshall Space Flight Center (MSFC), the fuel tank assembly for the Saturn V S-IC-T (static test stage) fuel tank assembly is mated to the liquid oxygen (LOX) tank in building 4705. This stage underwent numerous static firings at the newly-built S-IC Static Test Stand at the MSFC west test area. The S-IC (first) stage used five F-1 engines that produced a total thrust of 7,500,000 pounds as each engine produced 1,500,000 pounds of thrust. The S-IC stage lifted the Saturn V vehicle and Apollo spacecraft from the launch pad.
Formation of the heliospheric boundaries and the induced dynamics of the solar system: a multifluid view

NASA Astrophysics Data System (ADS)

Fahr, Hans-Jörg

2000-05-01

In many papers in the literature it is shown that wind-driving stars with a peculiar motion relative to the ambient interstellar medium within dynamical time periods form a dynamically adapted astropause as separatrix between the stellar wind plasma and the surrounding interstellar plasma. As we shall show in this chapter stars with an adapted astropause are subject to thrust forces finally acting on the wing-generating central body and thus influencing the stellar motion. Thereby the actual magnitude of the resulting thrust force depends on the actual counterflow configuration of stellar and interstellar winds determined by the particular kinematic situation, i.e. the instantaneous Mach number of the motion relative to the ambient medium. We shall study the sensitivity of this configuration to whether the interstellar flow is sub- or supersonic. The resulting net force is shown to vary in a non-monotonic way with the actual peculiar velocity. For subsonic motions this force generally has an accelerating nature, i.e. operating like a rocket thrust motor, whereas for supersonic motions at supercritical Mach numbers μS≥μS,c, to the contrary, it is of a decelerating nature. For an adequate description of a time-dependent circumstellar flow configuration, we shall use an analytic, hydrodynamic modeling of the counterflow configuration representing the case of a stellar wind system in subsonic or supersonic motion with respect to the local interstellar medium. For the purpose of analytical treatability we assume irrotational and incompressible flows downstream of the inner and outer shocks and give quantitative numbers for forces acting on the central star. We also describe long-period evolutions of star motions and give typical acceleration time periods for different types of wind-driving stars. As we shall emphasize here the dynamical influence of these thrust forces onto the central stellar body requires an understanding of how the presence of the counterflowing interstellar plasma is communicated upstream in the supersonic stellar wind up to the origin of this wind, the stellar corona. The answer we shall give is based on the multifluid character of the relevant counterflow situation invalidating the conventional mono-Mach-number concept of hydrodynamical flows. In fact stellar winds can only be described by a poly-Mach-number concept, with stellar-wind protons being supersonic, with pick-up ions being marginally sonic, and with electrons and anomalous cosmic ray particles being strongly subsonic. We shall present solutions for multifluid counterflow configurations based on computational simulations in which a consistent picture of the interaction of all these different species is given. Our final conclusion is that already the solar wind when passing over the Earth's orbit tells us about the interstellar medium beyond the heliopause.
Prograde evolution of the Scottish Caledonides and tectonic implications

NASA Astrophysics Data System (ADS)

Ashley, Kyle T.; Thigpen, J. Ryan; Law, Richard D.

2015-05-01

Recent thermometric analyses of samples collected in thrust-parallel structural transects across the Scandian (435-415 Ma) orogenic wedge in northwest Scotland provide a comprehensive characterization of the synorogenic retro-wedge thermal architecture. However, the paucity of petrologically-important metamorphic mineral phases (e.g., staurolite, Al-silicates) has limited investigation of pressure-temperature (P-T) histories, which hinders our ability to examine the nature of orogen-scale kinematic and thermal coupling. New data collected along a foreland-to-hinterland transect from the Moine to the Naver thrust sheets provides additional constraints for characterizing the prograde metamorphic evolution. In addition, we characterized Ti diffusion profiles in quartz inclusions in garnet to constrain duration of metamorphic heating. These results are used to develop coupled kinematic-thermal models of Scandian orogenic evolution. Early garnet core growth conditions are constrained by isopleth intersections, with peak P-T estimates determined by conventional exchange and net transfer thermobarometry and thermodynamic calculations. Most samples follow normal prograde heating and burial profiles, with peak conditions of 450 °C and 5.0 kbar in the immediate hanging wall to the Moine thrust, increasing in temperature and pressure to 733 °C and 9.5 kbar in the immediate hanging wall to the Naver thrust. These normal prograde pressure trajectories are interpreted to reflect burial of incipient thrust sheets beneath the overriding wedge at the leading edge of the orogen. Prograde heating coeval with burial is interpreted to result from surface-directed isotherm perturbation due to thrust-related advection in the overriding wedge. One exception to this is a sample from the top of the Moine thrust sheet, where prograde heating occurs during decompression (540 °C and 8.1 kbar to 590 °C and 7.0 kbar). In this case, the short lag times between motion on the Moine and Ben Hope thrusts may have limited advectionary heating until after exhumation associated with motion on the underlying Moine thrust was underway. Ti diffusion profiles in quartz inclusions in garnet suggest the near-peak thermal evolution of these rocks occurred over very short time scales (< 200,000 years). While most of the garnets are inferred to be Scandian in age, we document evidence for pre-Scandian garnet cores in structurally higher (more hinterland positioned) samples that must have grown under higher temperatures. In the hanging wall of the Moine thrust, high grossular garnets with estimated formation conditions > 9 kbar are probably of detrital origin.
Performance variation due to stiffness in a tuna-inspired flexible foil model.

PubMed

Rosic, Mariel-Luisa N; Thornycroft, Patrick J M; Feilich, Kara L; Lucas, Kelsey N; Lauder, George V

2017-01-17

Tuna are fast, economical swimmers in part due to their stiff, high aspect ratio caudal fins and streamlined bodies. Previous studies using passive caudal fin models have suggested that while high aspect ratio tail shapes such as a tuna's generally perform well, tail performance cannot be determined from shape alone. In this study, we analyzed the swimming performance of tuna-tail-shaped hydrofoils of a wide range of stiffnesses, heave amplitudes, and frequencies to determine how stiffness and kinematics affect multiple swimming performance parameters for a single foil shape. We then compared the foil models' kinematics with published data from a live swimming tuna to determine how well the hydrofoil models could mimic fish kinematics. Foil kinematics over a wide range of motion programs generally showed a minimum lateral displacement at the narrowest part of the foil, and, immediately anterior to that, a local area of large lateral body displacement. These two kinematic patterns may enhance thrust in foils of intermediate stiffness. Stiffness and kinematics exhibited subtle interacting effects on hydrodynamic efficiency, with no one stiffness maximizing both thrust and efficiency. Foils of intermediate stiffnesses typically had the greatest coefficients of thrust at the highest heave amplitudes and frequencies. The comparison of foil kinematics with tuna kinematics showed that tuna motion is better approximated by a zero angle of attack foil motion program than by programs that do not incorporate pitch. These results indicate that open questions in biomechanics may be well served by foil models, given appropriate choice of model characteristics and control programs. Accurate replication of biological movements will require refinement of motion control programs and physical models, including the creation of models of variable stiffness.

Experiments on a repetitively pulsed electrothermal thruster

NASA Technical Reports Server (NTRS)

Burton, R. L.; Fleischer, D.; Goldstein, S. A.; Tidman, D. A.

1987-01-01

This paper presents experimental results from an investigation of a pulsed electrothermal (PET) thruster using water propellant. The PET thruster is operated on a calibrated thrust stand, and produces a thrust to power ratio of T/P = 0.07 + or - 0.01 N/kW. The discharge conditions are inferred from a numerical model which predicts pressure and temperature levels of 300-500 atm and 20,000 K, respectively. These values in turn correctly predict the measured values of impulse bit and discharge resistance. The inferred ideal exhaust velocity from these conditions is 17 km/sec, but the injection of water propellant produces a test tank background pressure of 10-20 Torr, which reduces the exhaust velocity to 14 km/sec. This value corresponds to a thrust efficiency of 54 + or - 7 percent when all experimental errors are taken into account.
Differences between clinical "snap-shot" and "real-life" assessments of lumbar spine alignment and motion - What is the "real" lumbar lordosis of a human being?

PubMed

Dreischarf, Marcel; Pries, Esther; Bashkuev, Maxim; Putzier, Michael; Schmidt, Hendrik

2016-03-21

The individual lumbar lordosis and lumbar motion have been identified to play an important role in pathogenesis of low back pain and are essential references for preoperative planning and postoperative evaluation. The clinical "gold-standard" for measuring lumbar lordosis and its motion are radiological "snap-shots" taken while standing and during upper-body flexion and extension. The extent to which these clinically assessed values characterise lumbar alignment and its motion in daily life merits discussion. A non-invasive measurement-system was employed to measure lumbar lordosis and lumbar motion in 208 volunteers (age: 20-74yrs; ♀/♂: 115/93). For an initial short-term measurement, comparable with the clinical "snap-shot", lumbar lordosis and its motion were assessed while standing and during flexion and extension. Subsequently, volunteers were released to their daily lives while wearing the device, and measurements were performed during the following 24h. The average lumbar lordosis during 24h (8.0°) differed significantly from the standardised measurement while standing (33.3°). Ranges of motion were significantly different throughout the day compared to standing measurements. The influence of the factors age and gender on lordosis and its motion resulted in conflicting results between long- and short-term-measurements. In conclusion, results of short-term examinations differ considerably from the average values during real-life. These findings might be important for surgical planning and increase the awareness of the biomechanical challenges that spinal structures and implants face in real-life. Furthermore, long-term assessments of spinal alignment and motion during daily life can provide valid data on spinal function and can reveal the importance of influential factors. Copyright © 2016 Elsevier Ltd. All rights reserved.
Note: Dynamic analysis of a robotic fish motion with a caudal fin with vertical phase differences

NASA Astrophysics Data System (ADS)

Yun, Dongwon; Kim, Kyung-Soo; Kim, Soohyun; Kyung, Jinho; Lee, Sunghwi

2013-03-01

In this paper, a robotic fish with a caudal fin with vertical phase differences is studied, especially focusing on the energy consumption. Energies for thrusting a conventional robotic fish and one with caudal fin with vertical phase differences are obtained and compared each other. It is shown that a robotic fish with a caudal fin with vertical phase differences can save more energy, which implies the efficient thrusting via a vertically waving caudal fin.
Around Marshall

NASA Image and Video Library

1963-08-13

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. North of the massive S-IC test stand, the F-1 Engine test stand was built. Designed to assist in the development of the F-1 Engine, the F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo depicts the construction of the F-1 test stand as of August 13, 1963. All four of its tower legs are well underway into the skyline.
Around Marshall

NASA Image and Video Library

1963-01-14

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the S-IC test stand, related facilities were constructed during this time frame. Built just north of the massive S-IC test stand was the F-1 Engine test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability was provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This photo, taken January 14, 1963 depicts the F-1 test stand site with hoses pumping excess water from the site.
a Revision to the Tectonics of the Flores Back-Arc Thrust Zone, Indonesia?

NASA Astrophysics Data System (ADS)

Tikku, A. A.

2011-12-01

The Flores and Bali Basins are continental basins in the Flores back-arc thrust zone associated with Eocene subduction of the Indo-Australian plate beneath the Sunda plate followed by Miocene to present-day inversion/thrusting. The basins are east of Java and north of the islands of Bali, Lombok, Sumbawa and Flores in the East Java Sea area of Indonesia. The tectonic interpretation of these basins is based on seismic, bathymetry and gravity data and is also supported by present-day GPS measurements that demonstrate subduction is no longer active across the Flores thrust zone. Current thinking about the area is that the Flores Basin (on the east end of the thrust zone) had the most extension in the back-arc thrust and may be a proto-oceanic basin, though the option of a purely continental extensional basin can not be ruled out. The Bali Basin (on the west end of the thrust zone) is thought to be shallower and have experienced less continental thinning and extension than the Flores Basin. Depth to basement estimates from recently collected marine magnetic data indicate the depth of the Bali Basin may be comparable to the depth of the Flores Basin. Analysis of the marine magnetic data and potential implications of relative plate motions will be presented.
Comparison of erector spinae and hamstring muscle activities and lumbar motion during standing knee flexion in subjects with and without lumbar extension rotation syndrome.

PubMed

Kim, Si-hyun; Kwon, Oh-yun; Park, Kyue-nam; Kim, Moon-Hwan

2013-12-01

The aim of this study was to compare the activity of the erector spinae (ES) and hamstring muscles and the amount and onset of lumbar motion during standing knee flexion between individuals with and without lumbar extension rotation syndrome. Sixteen subjects with lumbar extension rotation syndrome (10 males, 6 females) and 14 healthy subjects (8 males, 6 females) participated in this study. During the standing knee flexion, surface electromyography (EMG) was used to measure muscle activity, and surface EMG electrodes were attached to both the ES and hamstring (medial and lateral) muscles. A three-dimensional motion analysis system was used to measure kinematic data of the lumbar spine. An independent-t test was conducted for the statistical analysis. The group suffering from lumbar extension rotation syndrome exhibited asymmetric muscle activation of the ES and decreased hamstring activity. Additionally, the group with lumbar extension rotation syndrome showed greater and earlier lumbar extension and rotation during standing knee flexion compared to the control group. These data suggest that asymmetric ES muscle activation and a greater amount of and earlier lumbar motion in the sagittal and transverse plane during standing knee flexion may be an important factor contributing to low back pain. Copyright © 2013 Elsevier Ltd. All rights reserved.
Equation of Motion of an Interstellar Bussard Ramjet with Radiation and Mass Losses

ERIC Educational Resources Information Center

Semay, Claude; Silvestre-Brac, Bernard

2008-01-01

An interstellar Bussard ramjet is a spaceship using the protons of the interstellar medium in a fusion engine to produce thrust. In recent papers, it was shown that the relativistic equation of motion of an ideal ramjet and that of a ramjet with radiation loss are analytical. When a mass loss appears, the limit speed of the ramjet is more strongly…
Around Marshall

NASA Image and Video Library

1963-01-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. The F-1 Engine test stand was built north of the massive S-IC test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. Looking North, this aerial taken January 15, 1963, gives a closer view of the deep hole for the F-1 test stand site in the forefront. The S-IC test stand with towers prominent is to the right of center, and the Block House is seen left of center.
Dynamic response and stability of a gas-lubricated Rayleigh-step pad

NASA Technical Reports Server (NTRS)

Cheng, C.; Cheng, H. S.

1973-01-01

The quasi-static, pressure characteristics of a gas-lubricated thrust bearing with shrouded, Rayleigh-step pads are determined for a time-varying film thickness. The axial response of the thrust bearing to an axial forcing function or an axial rotor disturbance is investigated by treating the gas film as a spring having nonlinear restoring and damping forces. These forces are related to the film thickness by a power relation. The nonlinear equation of motion in the axial mode is solved by the Ritz-Galerkin method as well as the direct, numerical integration. Results of the nonlinear response by both methods are compared with the response based on the linearized equation. Further, the gas-film instability of an infinitely wide Rayleigh step thrust pad is determined by solving the transient Reynolds equation coupled with the equation of the motion of the pad. Results show that the Rayleigh-step geometry is very stable for bearing number A up to 50. The stability threshold is shown to exist only for ultrahigh values of Lambda equal to or greater than 100, where the stability can be achieved by making the mass heavier than the critical mass.
Hydrodynamic interactions in metachronal paddling: effects of varying stroke kinematics

NASA Astrophysics Data System (ADS)

Samaee, Milad; Kasoju, Vishwa; Lai, Hong Kuan; Santhanakrishnan, Arvind

2017-11-01

Crustaceans such as shrimp and krill use a drag-based technique for propulsion, in which multiple pairs of limbs are paddled rhythmically from the tail to the head. Each limb is phase-shifted in time relative to its neighbor. Most studies of this type of metachronal swimming have focused on the jet formed in the animal's wake. However, synergistic hydrodynamic interactions between adjacent limbs in metachrony have received minimal attention. We used a dynamically scaled robotic model to experimentally investigate how variations in stroke kinematics impact inter-paddle hydrodynamic interactions and thrust generation. Physical models of limbs were fitted to the robot and paddled with two different motion profiles (MPs)-1) MP1: metachronal power stroke (PS) and metachronal recovery stroke (RS); and 2) MP2: metachronal PS and synchronous RS. Stroke frequency and amplitude were maintained constant across both MPs. Our results show that MP2 produced faster jets in the thrust-generating direction as compared to MP1. The necessity for a pause in MP2 after completion of PS by the paddles leading the motion, prior to executing the synchronous RS, aided in further downstream flow propagation. The effect of using asymmetric stroke kinematics on thrust generated will be discussed.
A robotic platform for studying sea lion thrust production

NASA Astrophysics Data System (ADS)

Leftwich, Megan; Patel, Rahi; Kulkarni, Aditya; Friedman, Chen

California Sea Lions are agile swimmers and, uniquely, use their foreflippers (rather than hind flipper undulation) to generate thrust. Recently, a sea lion flipper from a deceased subject was externally scanned in high detail for fluid dynamics research. The flipper's geometry is used in this work to build an accurate scaled down flipper model (approximately 68% of the full size span). The flipper model is placed in a water flume to obtain lift and drag force measurements. The unique trailing edge features are then examined for their effect on the measured forces by comparing to similar flipper models with a smooth trailing edge, sinusoidal trailing edge, and a saw-tooth trailing edge. Additionally, a robotic flipper is being designed and built, replicating the sea lion foreflipper anatomical structure. The robot is actuated by a set of servo motors and replicates the sea lion flipper clap motion based on previously extracted kinematics. The flipper tip speed is designed to match typical full scale Reynolds numbers for an acceleration from rest maneuver. The model is tested in the water flume as well to obtain the forces and flow structures during the thrust production phase of the flipper motion.
Effects of trunk-hip strengthening on standing in children with spastic diplegia: a comparative pilot study.

PubMed

Kim, Joong-Hwi; Seo, Hye-Jung

2015-05-01

[Purpose] This study evaluated the effects of trunk-hip strengthening exercise on trunk-hip activation and pelvic tilt motion during standing in children with spastic diplegia and compared the improvement of pelvic tilt between the modified trunk-hip strengthening exercise and conventional exercise. [Subjects and Methods] Ten ambulant children with spastic diplegia were randomized to the modified trunk-hip strengthening exercise (n = 5) or conventional exercise (n = 5) group. The intervention consisted of a 6-week modified trunk-hip strengthening exercise 3 times per week. The children were tested for trunk-hip muscles activation and pelvic tilt motion during standing by surface electromyography and an inclinometer before and after the intervention. [Results] The anterior pelvic tilt angle and activation of the extensor spinae, rectus femoris, and semitendinosus during standing decreased significantly in the modified exercise group. The activation of extensor spinae differed significantly between groups. [Conclusion] Compared to the conventional exercise, the modified exercise was more effective for trunk-hip activation improvement and anterior pelvic tilt motion decrease during standing in children with spastic diplegia. We suggest clinicians use an individually tailored modified trunk-hip strengthening exercise for strengthening the weakest muscle groups in children with standing ability problems.
Motion in a central field in the presence of a constant perturbing acceleration in a co-moving coordinate system

NASA Astrophysics Data System (ADS)

Sannikova, T. N.; Kholshevnikov, K. V.

2015-08-01

The motion of a point mass under the action of a gravitational force toward a central body and a perturbing acceleration P is considered. The magnitude of P is taken to be small compared to the main gravitational acceleration due to the central body, and the direction of P to be constant in a standard astronomical coordinate system with its origin at the central body and axes directed along the radius vector, the transversal, and the binormal. Consideration of a constant vector perturbing acceleration simplifies averaging of the Euler equations for the motion in osculating elements, making it straightforward to obtain evolutionary differential equations of motion in the mean elements, as was done earlier in a first small-parameter approximation. This paper is devoted to integration of the mean equations. The system is integratable by quadratures if at least one component of the perturbing acceleration is zero, and also if the orbit is initially circular. Moreover, all the quadratures can be expressed in terms of elementary functions and elliptical integrals of the first kind in Jacobi form. If all three components of P are non-zero, this problem reduces to a system of two first-order differential equations, which are apparently not integrable. Possible applications include the motion of natural and artificial satellites taking into account light pressure, the motion of a spacecraft with low thrust, and the motion of an asteroid subject to a thrust from an engine mounted on it or to a gravitational tractor designed, for example, to avoid a collision with Earth.
A new standing-wave-type linear ultrasonic motor based on in-plane modes.

PubMed

Shi, Yunlai; Zhao, Chunsheng

2011-05-01

This paper presents a new standing-wave-type linear ultrasonic motor using combination of the first longitudinal and the second bending modes. Two piezoelectric plates in combination with a metal thin plate are used to construct the stator. The superior point of the stator is its isosceles triangular structure part of the stator, which can amplify the displacement in horizontal direction of the stator in perpendicular direction when the stator is operated in the first longitudinal mode. The influence of the base angle θ of the triangular structure part on the amplitude of the driving foot has been analyzed by numerical analysis. Four prototype stators with different angles θ have been fabricated and the experimental investigation of these stators has validated the numerical simulation. The overall dimensions of the prototype stators are no more than 40 mm (length) × 20 mm (width) × 5 mm (thickness). Driven by an AC signal with the driving frequency of 53.3 kHz, the no-load speed and the maximal thrust of the prototype motor using the stator with base angle 20° were 98 mm/s and 3.2N, respectively. The effective elliptical motion trajectory of the contact point of the stator can be achieved by the isosceles triangular structure part using only two PZTs, and thus it makes the motor low cost in fabrication, simple in structure and easy to realize miniaturization. Copyright © 2010 Elsevier B.V. All rights reserved.
Hidden marker position estimation during sit-to-stand with walker.

PubMed

Yoon, Sang Ho; Jun, Hong Gul; Dan, Byung Ju; Jo, Byeong Rim; Min, Byung Hoon

2012-01-01

Motion capture analysis of sit-to-stand task with assistive device is hard to achieve due to obstruction on reflective makers. Previously developed robotic system, Smart Mobile Walker, is used as an assistive device to perform motion capture analysis in sit-to-stand task. All lower limb markers except hip markers are invisible through whole session. The link-segment and regression method is applied to estimate the marker position during sit-to-stand. Applying a new method, the lost marker positions are restored and the biomechanical evaluation of the sit-to-stand movement with a Smart Mobile Walker could be carried out. The accuracy of the marker position estimation is verified with normal sit-to-stand data from more than 30 clinical trials. Moreover, further research on improving the link segment and regression method is addressed.
Blue Origin testing

NASA Image and Video Library

2012-04-20

NASA Administrator Charles Bolden (r) discusses the upcoming testing of Blue Origin's BE-3 engine thrust chamber assembly with Steve Knowles, Blue Origin project manager, at the E-1 Test Stand during an April 20, 2012, visit to Stennis Space Center. Blue Origin is one of NASA's partners developing innovative systems to reach low-Earth orbit.
Mercury Retrorocket Tests

NASA Image and Video Library

1960-04-01

The retrorockets, which would be fired to return the Mercury Capsule to earth's atmosphere, were tested inside the Altitude Wind Tunnel in April 1960. A retrograde thrust stand was erected in the C corner in the wide end of the Altitude Wind Tunnel. This film contains footage from above and the side of the retrorockets firing.
19. HISTORIC VIEW OF MAX VALIER IN AN EARLY STATIC ...

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

19. HISTORIC VIEW OF MAX VALIER IN AN EARLY STATIC TEST. THE ROCKET IS SITTING ON A SCALE. VALIER IS MEASURING THRUST BY ADDING WEIGHT LIKE THE ONE IN HIS RIGHT HAND. - Marshall Space Flight Center, Redstone Rocket (Missile) Test Stand, Dodd Road, Huntsville, Madison County, AL
Saturn Apollo Program

NASA Image and Video Library

1964-03-01

The flame and exhaust from the test firing of an F-1 engine blast out from the Saturn S-IB Static Test Stand in the east test area of the Marshall Space Flight Center. A Cluster of five F-1 engines, located in the S-IC (first) stage of the Saturn V vehicle, provided over 7,500,000 pounds of thrust to launch the giant rocket. The towering 363-foot Saturn V was a multistage, multiengine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.

Addition of Passive Dynamics to a Flapping Airfoil to Improve Performance

NASA Astrophysics Data System (ADS)

Asselin, Daniel; Young, Jay; Williamson, C. H. K.

2017-11-01

Animals which fly or swim typically employ flapping motions of their wings and fins in order to produce thrust and to maneuver. Small, unmanned vehicles might also exploit such motions and are of considerable interest for the purposes of surveillance, environmental monitoring, and search and rescue. Flapping refers to a combination of pitch and heave and has been shown to provide good thrust and efficiency (Read, et al. 2003) when both axes are independently controlled (an Active-Active system). In this study, we examine the performance of an airfoil actuated only in the heave direction but allowed to pitch passively under the control of a torsion spring (an Active-Passive system). The presence of the spring is simulated in software using a force-feedback control system called Cyber-Physical Fluid Dynamics, or CPFD (Mackowski & Williamson 2011, 2015, 2016). Adding passive pitch to active heave provides significantly improved thrust and efficiency compared with heaving alone, especially when the torsion spring stiffness is selected so that the system operates near resonance (in an Active-Passive system). In many cases, values of thrust and efficiency are comparable to or better than those obtained with two actively controlled degrees of freedom. By using carefully-designed passive dynamics in the pitch direction, we can eliminate one of the two actuators, saving cost, complexity, and weight, while maintaining performance. This work was supported by the Air Force Office of Scientific Research Grant No. FA9550-15-1-0243, monitored by Dr. Douglas Smith.
Illustrations and supporting texts for sound standing waves of air columns in pipes in introductory physics textbooks

NASA Astrophysics Data System (ADS)

Zeng, Liang; Smith, Chris; Poelzer, G. Herold; Rodriguez, Jennifer; Corpuz, Edgar; Yanev, George

2014-12-01

In our pilot studies, we found that many introductory physics textbook illustrations with supporting text for sound standing waves of air columns in open-open, open-closed, and closed-closed pipes inhibit student understanding of sound standing wave phenomena due to student misunderstanding of how air molecules move within these pipes. Based on the construct of meaningful learning from cognitive psychology and semiotics, a quasiexperimental study was conducted to investigate the comparative effectiveness of two alternative approaches to student understanding: a traditional textbook illustration approach versus a newly designed air molecule motion illustration approach. Thirty volunteer students from introductory physics classes were randomly assigned to two groups of 15 each. Both groups were administered a presurvey. Then, group A read the air molecule motion illustration handout, and group B read a traditional textbook illustration handout; both groups were administered postsurveys. Subsequently, the procedure was reversed: group B read the air molecule motion illustration handout and group A read the traditional textbook illustration handout. This was followed by a second postsurvey along with an exit research questionnaire. The study found that the majority of students experienced meaningful learning and stated that they understood sound standing wave phenomena significantly better using the air molecule motion illustration approach. This finding provides a method for physics education researchers to design illustrations for abstract sound standing wave concepts, for publishers to improve their illustrations with supporting text, and for instructors to facilitate deeper learning in their students on sound standing waves.
Space Shuttle Projects

NASA Image and Video Library

1977-12-01

The solid rocket booster (SRB) structural test article is being installed in the Solid Rocket Booster Test Facility for the structural and load verification test at the Marshall Space Flight Center (MSFC). The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment.
Space Shuttle Projects

NASA Image and Video Library

1978-11-01

The structural test article to be used in the solid rocket booster (SRB) structural and load verification tests is being assembled in a high bay building of the Marshall Space Flight Center (MSFC). The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment.
Solid Rocket Booster Structural Test Article

NASA Technical Reports Server (NTRS)

1978-01-01

The structural test article to be used in the solid rocket booster (SRB) structural and load verification tests is being assembled in a high bay building of the Marshall Space Flight Center (MSFC). The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment.
Effect of Background Pressure on the Performance and Plume of the HiVHAc Hall Thruster

NASA Technical Reports Server (NTRS)

Huang, Wensheng; Kamhawi, Hani; Haag, Thomas

2013-01-01

During the Single String Integration Test of the NASA HiVHAc Hall thruster, a number of plasma diagnostics were implemented to study the effect of varying facility background pressure on thruster operation. These diagnostics include thrust stand, Faraday probe, ExB probe, and retarding potential analyzer. The test results indicated a rise in thrust and discharge current with background pressure. There was also a decrease in ion energy per charge, an increase in multiply-charged species production, a decrease in plume divergence, and a decrease in ion beam current with increasing background pressure. A simplified ingestion model was applied to determine the maximum acceptable background pressure for thrust measurement. The maximum acceptable ingestion percentage was found to be around 1%. Examination of the diagnostics results suggest the ionization and acceleration zones of the thruster were shifting upstream with increasing background pressure.
Blade Tip Pressure Measurements Using Pressure Sensitive Paint

NASA Technical Reports Server (NTRS)

Wong, Oliver D.; Watkins, Anthony Neal; Goodman, Kyle Z.; Crafton, James; Forlines, Alan; Goss, Larry; Gregory, James W.; Juliano, Thomas J.

2012-01-01

This paper discusses the application of pressure sensitive paint using laser-based excitation for measurement of the upper surface pressure distribution on the tips of rotor blades in hover and simulated forward flight. The testing was conducted in the Rotor Test Cell and the 14- by 22-ft Subsonic Tunnel at the NASA Langley Research Center on the General Rotor Model System (GRMS) test stand. The Mach-scaled rotor contained three chordwise rows of dynamic pressure transducers for comparison with PSP measurements. The rotor had an 11 ft 1 in. diameter, 5.45 in. main chord and a swept, tapered tip. Three thrust conditions were examined in hover, C(sub T) = 0.004, 0.006 and 0.008. In forward flight, an additional thrust condition, C(sub T) = 0.010 was also examined. All four thrust conditions in forward flight were conducted at an advance ratio of 0.35.
The alleged contributions of Pedro E. Paulet to liquid-propellant rocketry

NASA Technical Reports Server (NTRS)

Ordway, F. I., III

1977-01-01

The first practical working liquid propellant rocket motor was claimed by Pedro E. Paulet, a South American engineer from Peru (1895). He operated a conical motor, 10 centimeters in diameter, using nitrogen peroxide and gasoline as propellants and measuring thrust up to 90 kilograms, and apparently used spark ignition and intermittent propellant injection. The test device which he used contained elements of later test stands, such as a spring thrust-measuring device. However, he did not publish his work until twenty-five years later. Evidence is examined concerning this only known claim to liquid propellant rocket engine experiments in the nineteenth century.
Development Status of the NASA MC-1 (Fastrac) Engine

NASA Technical Reports Server (NTRS)

Ballard, Richard O.; Olive, Tim; Turner, James E. (Technical Monitor)

2000-01-01

The MC-1 (formerly known as the Fastrac 60K) Engine is being developed for the X-34 technology demonstrator vehicle. It is a pump-fed liquid rocket engine with fixed thrust operating at one rated power level of 60,000 lbf vacuum thrust using a 15:1 area ratio nozzle (slightly higher for the 30:1 flight nozzle). Engine system development testing of the MC-1 has been ongoing since 24 Oct 1998. To date, 48 tests have been conducted on three engines using three separate test stands. This paper will provide some details of the engine, the tests conducted, and the lessons learned to date.
Forces and energetics of intermittent swimming

NASA Astrophysics Data System (ADS)

Floryan, Daniel; Van Buren, Tyler; Smits, Alexander J.

2017-08-01

Experiments are reported on intermittent swimming motions. Water tunnel experiments on a nominally two-dimensional pitching foil show that the mean thrust and power scale linearly with the duty cycle, from a value of 0.2 all the way up to continuous motions, indicating that individual bursts of activity in intermittent motions are independent of each other. This conclusion is corroborated by particle image velocimetry (PIV) flow visualizations, which show that the main vortical structures in the wake do not change with duty cycle. The experimental data also demonstrate that intermittent motions are generally energetically advantageous over continuous motions. When metabolic energy losses are taken into account, this conclusion is maintained for metabolic power fractions less than 1.
Regularization in Orbital Mechanics; Theory and Practice

NASA Astrophysics Data System (ADS)

Roa, Javier

2017-09-01

Regularized equations of motion can improve numerical integration for the propagation of orbits, and simplify the treatment of mission design problems. This monograph discusses standard techniques and recent research in the area. While each scheme is derived analytically, its accuracy is investigated numerically. Algebraic and topological aspects of the formulations are studied, as well as their application to practical scenarios such as spacecraft relative motion and new low-thrust trajectories.
Vertical Motion Simulator Experiment on Stall Recovery Guidance

NASA Technical Reports Server (NTRS)

Schuet, Stefan; Lombaerts, Thomas; Stepanyan, Vahram; Kaneshige, John; Shish, Kimberlee; Robinson, Peter; Hardy, Gordon H.

2017-01-01

A stall recovery guidance system was designed to help pilots improve their stall recovery performance when the current aircraft state may be unrecognized under various complicating operational factors. Candidate guidance algorithms were connected to the split-cue pitch and roll flight directors that are standard on large transport commercial aircraft. A new thrust guidance algorithm and cue was also developed to help pilots prevent the combination of excessive thrust and nose-up stabilizer trim. The overall system was designed to reinforce the current FAA recommended stall recovery procedure. A general transport aircraft model, similar to a Boeing 757, with an extended aerodynamic database for improved stall dynamics simulation fidelity was integrated into the Vertical Motion Simulator at NASA Ames Research Center. A detailed study of the guidance system was then conducted across four stall scenarios with 30 commercial and 10 research test pilots, and the results are reported.
Design and demonstration of a fish robot actuated by a SMA-driven actuation system

NASA Astrophysics Data System (ADS)

Le, Chan H.; Nguyen, Quang S.; Park, Hoon C.

2010-04-01

This paper presents a concept of a fish robot actuated by an SMA-based actuator. The bending-type actuator system is composed of a 0.1mm diameter SMA wire and a 0.5mm thick glass/epoxy strip. The SMA wire is installed to the bent composite strip. The actuator can produce about 200gf of blocking force and 3.5mm displacement at the center of the glass/epoxy strip. The bending motion of the actuator is converted into the tail-beat motion of a fish robot through a linkage system. The fish robot is evaluated by measuring the tail-beat angle, swimming speed and thrust produced by the fish robot. The tail-beat angle is about 20° and the maximum swimming speed is about 1.6cm/s. The measured thrust is about 0.4gf when the fish robot is operated at 0.9Hz.
Influence of Total Inertia Effects in a Thrust Curvilinear Bearing Lubricated with Newtonian Lubricants

NASA Astrophysics Data System (ADS)

Walicka, A.; Jurczak, P.

2017-12-01

In the paper, the flow of a Newtonian type of lubricant in the clearance of a curvilinear bearing is considered. It is assumed that the bearing walls are modelled as smooth and impermeable. In analytical considerations, full inertia of the longitudinal flow and partial inertia of the circumferential flow are taken into account. The equation of motion of the lubricant is solved by the modified method of averaged inertia. A thrust bearing and spherical bearing are considered, for which dimensionless pressure distributions and the bearing capacity are given.
n/a

NASA Image and Video Library

1963-01-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. The F-1 Engine test stand was built north of the massive S-IC test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This aerial photograph, taken January 15, 1963, gives a close overall view of the newly developed test complex. Depicted in the forefront center is the S-IC test stand with towers prominent, the Block House is seen in the center just above the S-IC test stand, and the large hole to the left, located midway between the two is the F-1 test stand site.
n/a

NASA Image and Video Library

1963-01-15

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. Built directly east of the test stand was the Block House, which served as the control center for the test stand. The two were connected by a narrow access tunnel which housed the cables for the controls. The F-1 Engine test stand was built north of the massive S-IC test stand. The F-1 test stand is a vertical engine firing test stand, 239 feet in elevation and 4,600 square feet in area at the base, and was designed to assist in the development of the F-1 Engine. Capability is provided for static firing of 1.5 million pounds of thrust using liquid oxygen and kerosene. Like the S-IC stand, the foundation of the F-1 stand is keyed into the bedrock approximately 40 feet below grade. This aerial photograph, taken January 15, 1963 gives an overall view of the construction progress of the newly developed test complex. The large white building located in the center is the Block House. Just below and to the right of it is the S-IC test stand. The large hole to the left of the S-IC stand is the F-1 test stand site.
Saturn Apollo Program

NASA Image and Video Library

1966-01-01

Engineers and technicians at the Marshall Space Flight Center placed a Saturn V ground test booster (S-IC-D) into the dynamic test stand. The stand was constructed to test the integrity of the vehicle. Forces were applied to the tail of the vehicle to simulate the engines thrusting, and various other flight factors were fed to the vehicle to test reactions. The Saturn V launch vehicle, with the Apollo spacecraft, was subjected to more than 450 hours of shaking. The photograph shows the 300,000 pound S-IC stage being lifted from its transporter into place inside the 360-foot tall test stand. This dynamic test booster has one dummy F-1 engine and weight simulators are used at the other four engine positions.
The Influence of Chordwise Flexibility on the Flow Structure and Streamwise Force of a Sinusoidally Pitching Airfoil

NASA Astrophysics Data System (ADS)

Olson, David Arthur

Many natural flyers and swimmers need to exploit unsteady mechanisms in order to generate sufficient aerodynamic forces for sustained flight and propulsion. This is, in part, due to the low speed and length scales at which they typically operate. In this low Reynolds number regime, there are many unanswered questions on how existing aerodynamic theory for both steady and unsteady flows can be applied. Additionally, most of these natural flyers and swimmers have deformable wing/fin structures, three dimensional wing planforms, and exhibit complex kinematics during motion. While some biologically-inspired studies seek to replicate these complex structures and kinematics in the laboratory or in numerical simulations, it becomes difficult to draw explicit connections to the existing knowledge base of classical unsteady aerodynamic theory due to the complexity of the problems. In this experimental study, wing kinematics, structure, and planform are greatly simplified to investigate the effect of chordwise flexibility on the streamwise force (thrust) and wake behavior of a sinusoidally pitching airfoil. The study of flexibility in the literature has typically utilized flat plates with varying thicknesses or lengths to change their chordwise flexibility. This choice introduces additional complexities when comparing to the wealth of knowledge originally developed on streamlined aerodynamic shapes. The current study capitalizes on the recent developments in 3D printer technology to create accurate shapes out of materials with varying degrees of flexibility by creating two standard NACA 0009 airfoils: one rigid and one flexible. Each of the two airfoils are sinusoidally pitched about the quarter chord over a range of oscillation amplitudes and frequencies while monitoring the deformation of the airfoil. The oscillation amplitude is selected to be small enough such that leading edge vortices do not form, and the vortical structures in the wake are formed from the trailing edge. Two-component Molecular Tagging Velocimetry (MTV) is employed to measure the vortical flowfield over the first chord length behind the airfoil. A control volume method is used to estimate the mean thrust of the airfoil based on the mean and fluctuating velocity profiles from the MTV results. The mean thrust results show chordwise flexibility increases the thrust produced by the airfoil over the range of motion parameters and the flexibility considered in this study. The flexible airfoil is also seen to experience the drag-to-thrust crossover at a lower oscillation frequency than its rigid counterpart. The relative change in thrust due to flexibility decreases with increasing amplitude. The increase in thrust can, however, be captured as an amplitude effect when the Strouhal number based on the actual trailing edge displacement, Stte, is used for scaling. Scaling based strictly on the prescribed motion, typically employed in the literature, is not sufficient for the data to collapse. Motion trajectories which produced a classical von Karman vortex street or a reverse von Karman vortex street (depending on the arrangement of the vortices), are considered for further study. The vortices in the wake are characterized in terms of their strength, size, and spacing using phase-averaged MTV results. The circulation of the vortices are shown to collapse for both rigid and flexible airfoils when plotted against Stte. The actual trailing edge displacement is used as a length scale to normalize the transverse and streamwise spacing, and the vortex core size. These measurements also now collapse when plotted against Stte across oscillation amplitude for both the rigid and flexible airfoils.
Motion measurement of acoustically levitated object

NASA Technical Reports Server (NTRS)

Watkins, John L. (Inventor); Barmatz, Martin B. (Inventor)

1993-01-01

A system is described for determining motion of an object that is acoustically positioned in a standing wave field in a chamber. Sonic energy in the chamber is sensed, and variation in the amplitude of the sonic energy is detected, which is caused by linear motion, rotational motion, or drop shape oscillation of the object. Apparatus for detecting object motion can include a microphone coupled to the chamber and a low pass filter connected to the output of the microphone, which passes only frequencies below the frequency of sound produced by a transducer that maintains the acoustic standing wave field. Knowledge about object motion can be useful by itself, can be useful to determine surface tension, viscosity, and other information about the object, and can be useful to determine the pressure and other characteristics of the acoustic field.
A Design Tool for Matching UAV Propeller and Power Plant Performance

NASA Astrophysics Data System (ADS)

Mangio, Arion L.

A large body of knowledge is available for matching propellers to engines for large propeller driven aircraft. Small UAV's and model airplanes operate at much lower Reynolds numbers and use fixed pitch propellers so the information for large aircraft is not directly applicable. A design tool is needed that takes into account Reynolds number effects, allows for gear reduction, and the selection of a propeller optimized for the airframe. The tool developed in this thesis does this using propeller performance data generated from vortex theory or wind tunnel experiments and combines that data with an engine power curve. The thrust, steady state power, RPM, and tip Mach number vs. velocity curves are generated. The Reynolds number vs. non dimensional radial station at an operating point is also found. The tool is then used to design a geared power plant for the SAE Aero Design competition. To measure the power plant performance, a purpose built engine test stand was built. The characteristics of the engine test stand are also presented. The engine test stand was then used to characterize the geared power plant. The power plant uses a 26x16 propeller, 100/13 gear ratio, and an LRP 0.30 cubic inch engine turning at 28,000 RPM and producing 2.2 HP. Lastly, the measured power plant performance is presented. An important result is that 17 lbf of static thrust is produced.

The kinematics of crustal deformation in Java from GPS observations: Implications for fault slip partitioning

NASA Astrophysics Data System (ADS)

Koulali, A.; McClusky, S.; Susilo, S.; Leonard, Y.; Cummins, P.; Tregoning, P.; Meilano, I.; Efendi, J.; Wijanarto, A. B.

2017-01-01

Our understanding of seismic risk in Java has been focused primarily on the subduction zone, where the seismic records during the last century have shown the occurrence of a number of tsunami earthquakes. However, the potential of the existence of active crustal structures within the island of Java itself is less well known. Historical archives show the occurrence of several devastating earthquake ruptures north of the volcanic arc in west Java during the 18th and the 19th centuries, suggesting the existence of active faults that need to be identified in order to guide seismic hazard assessment. Here we use geodetic constraints from the Global Positioning System (GPS) to quantify the present day crustal deformation in Java. The GPS velocities reveal a homogeneous counterclockwise rotation of the Java Block independent of Sunda Block, consistent with a NE-SW convergence between the Australian Plate and southeast Asia. Continuous GPS observations show a time-dependent change in the linear rate of surface motion in west Java, which we interpret as an ongoing long-term post-seismic deformation following the 2006 Mw 7.7 Java earthquake. We use an elastic block model in combination with a viscoelastic model to correct for this post-seismic transient and derive the long-term inter-seismic velocity, which we interpret as a combination of tectonic block motions and crustal faults strain related deformation. There is a north-south gradient in the resulting velocity field with a decrease in the magnitude towards the North across the Kendeng Thrust in the east and the Baribis Thrust in the west. We suggest that the Baribis Thrust is active and accommodating a slow relative motion between Java and the Sunda Block at about 5 ± 0.2 mm /yr. We propose a kinematic model of convergence of the Australian Plate and the Sunda Block, involving a slip partitioning between the Java Trench and a left-lateral structure extending E-W along Java with most of the convergence being accommodated by the Java megathrust, and a much smaller parallel motion accommodated along the Baribis (∼ 5 ± 0.2 mm /yr) and Kendeng (∼ 2.3 ± 0.7 mm /yr) Thrusts. Our study highlights a correlation between the geodetically inferred active faults and historical seismic catalogs, emphasizing the importance of considering crustal fault activity within Java in future seismic assessments.
Stability basin estimates fall risk from observed kinematics, demonstrated on the Sit-to-Stand task.

PubMed

Shia, Victor; Moore, Talia Yuki; Holmes, Patrick; Bajcsy, Ruzena; Vasudevan, Ram

2018-04-27

The ability to quantitatively measure stability is essential to ensuring the safety of locomoting systems. While the response to perturbation directly reflects the stability of a motion, this experimental method puts human subjects at risk. Unfortunately, existing indirect methods for estimating stability from unperturbed motion have been shown to have limited predictive power. This paper leverages recent advances in dynamical systems theory to accurately estimate the stability of human motion without requiring perturbation. This approach relies on kinematic observations of a nominal Sit-to-Stand motion to construct an individual-specific dynamic model, input bounds, and feedback control that are then used to compute the set of perturbations from which the model can recover. This set, referred to as the stability basin, was computed for 14 individuals, and was able to successfully differentiate between less and more stable Sit-to-Stand strategies for each individual with greater accuracy than existing methods. Copyright © 2018 Elsevier Ltd. All rights reserved.
Large-scale fault interactions at the termination of a subduction margin

NASA Astrophysics Data System (ADS)

Mouslopoulou, V.; Nicol, A., , Prof; Moreno, M.; Oncken, O.; Begg, J.; Kufner, S. K.

2017-12-01

Active subduction margins terminate against, and transfer their slip onto, plate-boundary transform faults. The manner in which plate motion is accommodated and partitioned across such kinematic transitions from thrust to strike-slip faulting over earthquake timescales, is poorly documented. The 2016 November 14th, Mw 7.8 Kaikoura Earthquake provides a rare snapshot of how seismic-slip may be accommodated at the tip of an active subduction margin. Analysis of uplift data collected using a range of techniques (field measurements, GPS, LiDAR) and published mapping coupled with 3D dislocation modelling indicates that earthquake-slip ruptured multiple faults with various orientations and slip mechanisms. Modelled and measured uplift patterns indicate that slip on the plate-interface was minor. Instead, a large offshore thrust fault, modelled to splay-off the plate-interface and to extend to the seafloor up to 15 km east of the South Island, appears to have released subduction-related strain and to have facilitated slip on numerous, strike-slip and oblique-slip faults on its hanging-wall. The Kaikoura earthquake suggests that these large splay-thrust faults provide a key mechanism in the transfer of plate motion at the termination of a subduction margin and represent an important seismic hazard.
F-1 Engine for Saturn V Undergoing a Static Test

NASA Technical Reports Server (NTRS)

1964-01-01

The flame and exhaust from the test firing of an F-1 engine blast out from the Saturn S-IB Static Test Stand in the east test area of the Marshall Space Flight Center. A Cluster of five F-1 engines, located in the S-IC (first) stage of the Saturn V vehicle, provided over 7,500,000 pounds of thrust to launch the giant rocket. The towering 363-foot Saturn V was a multistage, multiengine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.
Growth stratal records of instantaneous and progressive limb rotation in the Precordillera thrust belt and Bermejo basin, Argentina

NASA Astrophysics Data System (ADS)

Zapata, TomáS. R.; Allmendinger, Richard W.

1996-10-01

Analysis of synorogenic deposits preserved near the thrust front zone of the Precordillera fold and thrust belt and in the Bermejo foreland basin in central Argentina documents the evolution of deformation during the last 5 Myr as well as the thrust system kinematics. Seismic lines across the area display examples of progressive and instantaneous limb rotations. The easternmost thrust plate of the Central Precordillera, the Niquivil thrust, experienced episodic motion in two main stages: a first thrust movement as a fault-propagation fold and a second movement as a high-angle anticlinal breakthrough fault after a period of quiescence. Growth strata deposited in the La Pareja intermontane basin and the Las Salinas and Bermejo anticline recorded continuous growth of Eastern Precordilleran structures beginning at ˜2.7 Ma, with uplift rates of ˜0.3 mm/yr for the Niquivil anticline, 1.08 mm/yr for the Las Salinas anticline, and between ˜0.6 and 0.38 mm/yr during the last ˜2 Myr for the Bermejo anticline. Once the Eastern Precordillera began to grow, the propagation of the Niquivil thrust stopped, restricting the deformation to the young Vallecito out-of sequence thrust. The complex geometry of growth strata deposited on the back limb of the Las Salinas anticline can be explained by using a model of a two-step fault propagation fold with constant layer thickness. The Bermejo anticline of the Eastern Precordillera is formed by the simultaneous propagation of a shallow fault, responsible for the fold shape, and a deep fault that produced vertical uplift. A growth triangle that documents instantaneous forelimb rotation for a fault-propagation fold is recorded for the first time in a published seismic line.
Rapid space trajectory generation using a Fourier series shape-based approach

NASA Astrophysics Data System (ADS)

Taheri, Ehsan

With the insatiable curiosity of human beings to explore the universe and our solar system, it is essential to benefit from larger propulsion capabilities to execute efficient transfers and carry more scientific equipments. In the field of space trajectory optimization the fundamental advances in using low-thrust propulsion and exploiting the multi-body dynamics has played pivotal role in designing efficient space mission trajectories. The former provides larger cumulative momentum change in comparison with the conventional chemical propulsion whereas the latter results in almost ballistic trajectories with negligible amount of propellant. However, the problem of space trajectory design translates into an optimal control problem which is, in general, time-consuming and very difficult to solve. Therefore, the goal of the thesis is to address the above problem by developing a methodology to simplify and facilitate the process of finding initial low-thrust trajectories in both two-body and multi-body environments. This initial solution will not only provide mission designers with a better understanding of the problem and solution but also serves as a good initial guess for high-fidelity optimal control solvers and increases their convergence rate. Almost all of the high-fidelity solvers enjoy the existence of an initial guess that already satisfies the equations of motion and some of the most important constraints. Despite the nonlinear nature of the problem, it is sought to find a robust technique for a wide range of typical low-thrust transfers with reduced computational intensity. Another important aspect of our developed methodology is the representation of low-thrust trajectories by Fourier series with which the number of design variables reduces significantly. Emphasis is given on simplifying the equations of motion to the possible extent and avoid approximating the controls. These facts contribute to speeding up the solution finding procedure. Several example applications of two and three-dimensional two-body low-thrust transfers are considered. In addition, in the multi-body dynamic, and in particular the restricted-three-body dynamic, several Earth-to-Moon low-thrust transfers are investigated.
Vortex flow structures and interactions for the optimum thrust efficiency of a heaving airfoil at different mean angles of attack

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martín-Alcántara, A.; Fernandez-Feria, R.; Sanmiguel-Rojas, E.

The thrust efficiency of a two-dimensional heaving airfoil is studied computationally for a low Reynolds number using a vortex force decomposition. The auxiliary potentials that separate the total vortex force into lift and drag (or thrust) are obtained analytically by using an elliptic airfoil. With these auxiliary potentials, the added-mass components of the lift and drag (or thrust) coefficients are also obtained analytically for any heaving motion of the airfoil and for any value of the mean angle of attack α. The contributions of the leading- and trailing-edge vortices to the thrust during their down- and up-stroke evolutions are computedmore » quantitatively with this formulation for different dimensionless frequencies and heave amplitudes (St{sub c} and St{sub a}) and for several values of α. Very different types of flows, periodic, quasi-periodic, and chaotic described as St{sub c}, St{sub a}, and α, are varied. The optimum values of these parameters for maximum thrust efficiency are obtained and explained in terms of the interactions between the vortices and the forces exerted by them on the airfoil. As in previous numerical and experimental studies on flapping flight at low Reynolds numbers, the optimum thrust efficiency is reached for intermediate frequencies (St{sub c} slightly smaller than one) and a heave amplitude corresponding to an advance ratio close to unity. The optimal mean angle of attack found is zero. The corresponding flow is periodic, but it becomes chaotic and with smaller average thrust efficiency as |α| becomes slightly different from zero.« less
Modelling resonances of the standing body exposed to vertical whole-body vibration: Effects of posture

NASA Astrophysics Data System (ADS)

Subashi, G. H. M. J.; Matsumoto, Y.; Griffin, M. J.

2008-10-01

Lumped parameter mathematical models representing anatomical parts of the human body have been developed to represent body motions associated with resonances of the vertical apparent mass and the fore-and-aft cross-axis apparent mass of the human body standing in five different postures: 'upright', 'lordotic', 'anterior lean', 'knees bent', and 'knees more bent'. The inertial and geometric parameters of the models were determined from published anthropometric data. Stiffness and damping parameters were obtained by comparing model responses with experimental data obtained previously. The principal resonance of the vertical apparent mass, and the first peak in the fore-and-aft cross-axis apparent mass, of the standing body in an upright posture (at 5-6 Hz) corresponded to vertical motion of the viscera in phase with the vertical motion of the entire body due to deformation of the tissues at the soles of the feet, with pitch motion of the pelvis out of phase with pitch motion of the upper body above the pelvis. Upward motion of the body was in phase with the forward pitch motion of the pelvis. Changing the posture of the upper body had minor effects on the mode associated with the principal resonances of the apparent mass and cross-axis apparent mass, but the mode changed significantly with bending of the legs. In legs-bent postures, the principal resonance (at about 3 Hz) was attributed to bending of the legs coupled with pitch motion of the pelvis in phase with pitch motion of the upper body. In this mode, extension of the legs was in phase with the forward pitch motion of the upper body and the upward vertical motion of the viscera.
Flight-Determined Subsonic Longitudinal Stability and Control Derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) with Thrust Vectoring

NASA Technical Reports Server (NTRS)

Iliff, Kenneth W.; Wang, Kon-Sheng Charles

1997-01-01

The subsonic longitudinal stability and control derivatives of the F-18 High Angle of Attack Research Vehicle (HARV) are extracted from dynamic flight data using a maximum likelihood parameter identification technique. The technique uses the linearized aircraft equations of motion in their continuous/discrete form and accounts for state and measurement noise as well as thrust-vectoring effects. State noise is used to model the uncommanded forcing function caused by unsteady aerodynamics over the aircraft, particularly at high angles of attack. Thrust vectoring was implemented using electrohydraulically-actuated nozzle postexit vanes and a specialized research flight control system. During maneuvers, a control system feature provided independent aerodynamic control surface inputs and independent thrust-vectoring vane inputs, thereby eliminating correlations between the aircraft states and controls. Substantial variations in control excitation and dynamic response were exhibited for maneuvers conducted at different angles of attack. Opposing vane interactions caused most thrust-vectoring inputs to experience some exhaust plume interference and thus reduced effectiveness. The estimated stability and control derivatives are plotted, and a discussion relates them to predicted values and maneuver quality.
Hydrodynamic studies on two traveling wavy foils in tandem arrangement

NASA Astrophysics Data System (ADS)

Deng, Jian; Shao, Xue-Ming; Yu, Zhao-Sheng

2007-11-01

In this study, the hydrodynamic interactions between two tandem foils undergoing fishlike swimming motion are investigated numerically by solving the Navier-Stokes equations with the immersed-boundary method. The two foils represent two tandem propellers attached on a concept ship. The thrusts and efficiencies at three typical Strouhal numbers, i.e., St =0.4, 0.6, and 0.8, are investigated. The results show that a fish situated directly behind another one does not always undergo a lower thrust. Whether it experiences a thrust enhancement or reduction depends on the Strouhal number. At a relatively low Strouhal number (e.g., St =0.4), the usual wake drag-reduction effect predominates over the drag-enhancement effect caused by the reverse von Kármán vortices, resulting in a thrust enhancement. The opposite happens at a relatively high Strouhal number (e.g., St =0.8). The downstream fish can benefit from the upstream one by slalom between the vortices rather than through them. For the upstream fish, the thrusts and efficiencies for all Strouhal numbers studied are higher than those for a single fish when the two fish are closely spaced, and approach those for a single fish as the spacing is increased.
Spin Stabilized Impulsively Controlled Missile (SSICM)

NASA Astrophysics Data System (ADS)

Crawford, J. I.; Howell, W. M.

1985-12-01

This patent is for the Spin Stabilized Impulsively Controlled Missile (SSICM). SSICM is a missile configuration which employs spin stabilization, nutational motion, and impulsive thrusting, and a body mounted passive or semiactive sensor to achieve very small miss distances against a high speed moving target. SSICM does not contain an autopilot, control surfaces, a control actuation system, nor sensor stabilization gimbals. SSICM spins at a rate sufficient to provide frequency separation between body motions and inertial target motion. Its impulsive thrusters provide near instantaneous changes in lateral velocity, whereas conventional missiles require a significant time delay to achieve lateral acceleration.
Fault Structural Control on Earthquake Strong Ground Motions: The 2008 Wenchuan Earthquake as an Example

NASA Astrophysics Data System (ADS)

Zhang, Yan; Zhang, Dongli; Li, Xiaojun; Huang, Bei; Zheng, Wenjun; Wang, Yuejun

2018-02-01

Continental thrust faulting earthquakes pose severe threats to megacities across the world. Recent events show the possible control of fault structures on strong ground motions. The seismogenic structure of the 2008 Wenchuan earthquake is associated with high-angle listric reverse fault zones. Its peak ground accelerations (PGAs) show a prominent feature of fault zone amplification: the values within the 30- to 40-km-wide fault zone block are significantly larger than those on both the hanging wall and the footwall. The PGA values attenuate asymmetrically: they decay much more rapidly in the footwall than in the hanging wall. The hanging wall effects can be seen on both the vertical and horizontal components of the PGAs, with the former significantly more prominent than the latter. All these characteristics can be adequately interpreted by upward extrusion of the high-angle listric reverse fault zone block. Through comparison with a low-angle planar thrust fault associated with the 1999 Chi-Chi earthquake, we conclude that different fault structures might have controlled different patterns of strong ground motion, which should be taken into account in seismic design and construction.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, John

This project aims to understand the characteristics of the free-field strong-motion records that have yielded the 100 largest peak accelerations and the 100 largest peak velocities recorded to date. The peak is defined as the maximum magnitude of the acceleration or velocity vector during the strong shaking. This compilation includes 35 records with peak acceleration greater than gravity, and 41 records with peak velocities greater than 100 cm/s. The results represent an estimated 150,000 instrument-years of strong-motion recordings. The mean horizontal acceleration or velocity, as used for the NGA ground motion models, is typically 0.76 times the magnitude of thismore » vector peak. Accelerations in the top 100 come from earthquakes as small as magnitude 5, while velocities in the top 100 all come from earthquakes with magnitude 6 or larger. Records are dominated by crustal earthquakes with thrust, oblique-thrust, or strike-slip mechanisms. Normal faulting mechanisms in crustal earthquakes constitute under 5% of the records in the databases searched, and an even smaller percentage of the exceptional records. All NEHRP site categories have contributed exceptional records, in proportions similar to the extent that they are represented in the larger database.« less
Dynamic Simulations for the Seismic Behavior on the Shallow Part of the Fault Plane in the Subduction Zone during Mega-Thrust Earthquakes

NASA Astrophysics Data System (ADS)

Tsuda, K.; Dorjapalam, S.; Dan, K.; Ogawa, S.; Watanabe, T.; Uratani, H.; Iwase, S.

2012-12-01

The 2011 Tohoku-Oki earthquake (M9.0) produced some distinct features such as huge slips on the order of several ten meters around the shallow part of the fault and different areas with radiating seismic waves for different periods (e.g., Lay et al., 2012). These features, also reported during the past mega-thrust earthquakes in the subduction zone such as the 2004 Sumatra earthquake (M9.2) and the 2010 Chile earthquake (M8.8), get attentions as the distinct features if the rupture of the mega-thrust earthquakes reaches to the shallow part of the fault plane. Although various kinds of observations for the seismic behavior (rupture process and ground motion characteristics etc.) on the shallow part of the fault plane during the mega-trust earthquakes have been reported, the number of analytical or numerical studies based on dynamic simulation is still limited. Wendt et al. (2009), for example, revealed that the different distribution of initial stress produces huge differences in terms of the seismic behavior and vertical displacements on the surface. In this study, we carried out the dynamic simulations in order to get a better understanding about the seismic behavior on the shallow part of the fault plane during mega-thrust earthquakes. We used the spectral element method (Ampuero, 2009) that is able to incorporate the complex fault geometry into simulation as well as to save computational resources. The simulation utilizes the slip-weakening law (Ida, 1972). In order to get a better understanding about the seismic behavior on the shallow part of the fault plane, some parameters controlling seismic behavior for dynamic faulting such as critical slip distance (Dc), initial stress conditions and friction coefficients were changed and we also put the asperity on the fault plane. These understandings are useful for the ground motion prediction for future mega-thrust earthquakes such as the earthquakes along the Nankai Trough.
Busy test week

NASA Image and Video Library

2012-11-08

Jason Hopper of NASA (front row), Jody Ladner of Lockheed Martin (back row, left) and Chris Mulkey of NASA prepare to test the Blue Origin BE-3 engine thrust chamber in the E-1 Test Stand Control Center at John C. Stennis Space Center on Nov. 8. The test was one of 27 conducted in Stennis' E Test Complex the week of Nov. 5.
A 205 Hour Krypton Propellant Life Test of the SPT-100 Operating at 3 kW

DTIC Science & Technology

2013-09-01

advantageous, such as orbit raising missions. Bismuth’s main drawback is that the metal must be vaporized to be ionized and accelerated within a Hall...the performance of the SPT-100 operating on krypton was characterized using an inverted pendulum thrust stand over a wide range of thruster operating
RS-25 Engines Powered to Highest Level Ever During Stennis Test

NASA Image and Video Library

2018-02-21

Operators powered NASA’s Space Launch System (SLS) engine to 113 percent thrust level, the highest RS-25 power level yet achieved, for 50 seconds of a 260-second test on February 21 at Stennis Space Center. This was the third full-duration test conducted on the A-1 Test Stand at Stennis this year.
RS-25 Engines Powered to Highest Level Ever during Stennis Test

NASA Image and Video Library

2018-02-21

Operators powered NASA’s Space Launch System (SLS) engine to 113 percent thrust level, the highest RS-25 power level yet achieved, for 50 seconds of a 260-second test on February 21 at Stennis Space Center. This was the third full-duration test conducted on the A-1 Test Stand at Stennis this year.
An Integrated Geophysical and Geological Investigation of the Transition Zone between the Colorado Plateau, Rio Grande Rift and Basin and Range Provinces: Arizona and New Mexico

DTIC Science & Technology

1990-12-01

The thrust faults often contain enough strike- slip motion to be termed oblique faults (Seager and...Chapin cites the presence of left-lateral 160 oblique slip faults at its northern and southern boundaries, that the down- faulted section almost...and Bilodeau (1984) report that strike- slip motion may involve pre-existing faults , possibly faults associated with the Antler orogeny (Coney,
Postural response latencies are related to balance control during standing and walking in patients with multiple sclerosis

PubMed Central

Huisinga, Jessie M.; St. George, Rebecca J.; Spain, Rebecca; Overs, Shannon; Horak, Fay B.

2015-01-01

Objective To understand examined the relationship between postural response latencies obtained during postural perturbations and representative measures of balance during standing (sway variables) and during walking (trunk motion). Design Cross-sectional Setting University medical center balance disorders laboratory Participants Forty persons with MS were compared with 20 similar aged control subjects. Twenty subjects with MS had normal walking velocity group and 20 had slow walking velocity based on the 25-foot walk time greater than 5 seconds. Interventions None Main Outcome Measures Postural response latency, sway variables, trunk motion variables Results: We found that subjects with MS with either slow or normal walking velocities had significantly longer postural response latencies than the healthy control group. Postural response latency was not correlated with the 25-ft walk time. Postural response latency was significantly correlated with center of pressure sway variables during quiet standing: root mean square (ρ = 0.334, p=0.040), range (ρ=0.385, p=0.017), mean velocity (ρ=0.337, p=0.038), and total sway area (ρ=0.393, p=0.015). Postural response latency was also significantly correlated with motion of the trunk during walking: sagittal plane range of motion (ρ=0.316, p=0.050) and standard deviation of transverse plane range of motion (ρ=-0.430, p=0.006). Conclusions These findings clearly indicate that slow postural responses to external perturbations in patients with MS contribute to disturbances in balance control, both during standing and walking. PMID:24445088

Theoretical peak performance and optical constraints for the deflection of an S-type asteroid with a continuous wave laser

NASA Astrophysics Data System (ADS)

Thiry, Nicolas; Vasile, Massimiliano

2017-03-01

This paper presents a theoretical model to evaluate the thrust generated by a continuous wave (CW) laser, operating at moderate intensity (<100 GW/m2), ablating an S-type asteroid made of Forsterite. The key metric to assess the performance of the laser system is the thrust coupling coefficient which is given by the ratio between thrust and associated optical power. Three different models are developed in the paper: a one dimensional steady state model, a full 3D steady state model and a one dimensional model accounting for transient effects resulting from the tumbling motion of the asteroid. The results obtained with these models are used to derive key requirements and constraints on the laser system that allow approaching the ideal performance in a realistic case.
Analytical Method of Approximating the Motion of a Spinning Vehicle with Variable Mass and Inertia Properties Acted Upon by Several Disturbing Parameters

NASA Technical Reports Server (NTRS)

Buglia, James J.; Young, George R.; Timmons, Jesse D.; Brinkworth, Helen S.

1961-01-01

An analytical method has been developed which approximates the dispersion of a spinning symmetrical body in a vacuum, with time-varying mass and inertia characteristics, under the action of several external disturbances-initial pitching rate, thrust misalignment, and dynamic unbalance. The ratio of the roll inertia to the pitch or yaw inertia is assumed constant. Spin was found to be very effective in reducing the dispersion due to an initial pitch rate or thrust misalignment, but was completely Ineffective in reducing the dispersion of a dynamically unbalanced body.
Summary of the stratigraphy and structural elements related to plate convergence of the Quetta-Muslim Bagh-Sibi region, Balochistan, west-central Pakistan

USGS Publications Warehouse

Maldonado, Florian; Mengal, Jan M.; Khan, Shahid H.; Warwick, Peter D.

2011-01-01

The four major faults that bound the structural terrane are the Frontal (F), Ghazaband-Zhob (GZ), Gwal-Bagh (GB), and Chaman (C) faults. Four major periods of deformation are recognized: (1) emplacement of ophiolitic rocks onto the continental margin of the India plate; (2) convergence of the India-Eurasia plates; (3) deposition of Tertiary-Quaternary molasse units followed by major folding and thrusting, and formation of strike-slip faults; and (4) deposition of Pleistocene molasse units with subsequent folding, thrusting, and strike-slip motion that continues to the present.
Investigation of a pulsed electrothermal thruster system

NASA Technical Reports Server (NTRS)

Burton, R. L.; Goldstein, S. A.; Hilko, B. K.; Tidman, D. A.; Winsor, N. K.

1984-01-01

The performance of an ablative wall Pulsed Electrothermal (PET) thruster is accurately characterized on a calibrated thrust stand, using polyethylene propellant. The thruster is tested for four configurations of capillary length and pulse length. The exhaust velocity is determined with twin time-of-flight photodiode stagnation probes, and the ablated mass is measured from the loss over ten shots. Based on the measured thrust impulse and the ablated mass, the specific impulse varies from 1000 to 1750 seconds. The thrust to power varies from .05 N/kW (quasi-steady mode) to .10 N/kW (unsteady mode). The thruster efficiency varies from .56 at 1000 seconds to .42 at 1750 seconds. A conceptual design is presented for a 40 kW PET propulsion system. The point design system performance is .62 system efficiency at 1000 seconds specific impulse. The system's reliability is enhanced by incorporating 20, 20 kW thruster modules which are fired in pairs. The thruster design is non-ablative, and uses water propellant, from a central storage tank, injected through the cathode.
Numerical Elasto-Plastic Models on the Faulting development in Southwest Taiwan

NASA Astrophysics Data System (ADS)

Lee, F. Y.; Tan, E.; Chang, E. T. Y.

2016-12-01

We use 3D numerical elasto-plastic model to simulate the development of faults and the surface deformation in Southwest Taiwan, which is under oblique collision between Eurasian plate and Philippine Sea plate. The study area is bounded by the Central Range and the Peikang basement high, comprising the southernmost part of the fold-and-thrust belt joint with the coastal plain (mainly the Pingtung Plain). Our goal is to model the deformation mechanism under oblique collision of plates in and around the Taiwan Island. The Cenozoic sediment isopach is taken to form our experimental domain. The Chaochou fault locates at the eastern boundary, serving as a bulldozer moving westward in a velocity of 5 cm/yr. The Peikang high is the backstop at western boundary with material in various friction angle attached to supply friction. The northern boundary striking in E-W direction is at the northern end of the Chaochou fault as a frictional boundary. The southern boundary is in the offshore area of the Pingtung Plain with an open boundary, which allows material free to flow out. A thin layer with variable frictions is at the bottom. Our results show a significant correlation with the tectonic structures observed in the SW Taiwan. The motion velocity increases from north to south, which is similar to the GPS observation. Additionally, two longitudinal thrusts are generated at east. They correspond to the Chaochou fault and Koaping fault, the latter of which is reported as a thrust with sinistral motion. Furthermore, several sinistral strike-slip faults are emergent in the southeast in our experiment. In fact, the bathymetry in the SW offshore Taiwan reveals a lateral motion within the strata in the accretionary prism.
Hydrodynamics of a robotic fish tail: effects of the caudal peduncle, fin ray motions and the flow speed.

PubMed

Ren, Ziyu; Yang, Xingbang; Wang, Tianmiao; Wen, Li

2016-02-08

Recent advances in understanding fish locomotion with robotic devices have included the use of biomimetic flapping based and fin undulatory locomotion based robots, treating two locomotions separately from each other. However, in most fish species, patterns of active movements of fins occur in concert with the body undulatory deformation during swimming. In this paper, we describe a biomimetic robotic caudal fin programmed with individually actuated fin rays to mimic the fin motion of the Bluegill Sunfish (Lepomis macrochirus) and coupled with heave and pitch oscillatory motions adding to the robot to mimic the peduncle motion which is derived from the undulatory fish body. Multiple-axis force and digital particle image velocimetry (DPIV) experiments from both the vertical and horizontal planes behind the robotic model were conducted under different motion programs and flow speeds. We found that both mean thrust and lift could be altered by changing the phase difference (φ) from 0° to 360° between the robotic caudal peduncle and the fin ray motion (spanning from 3 mN to 124 mN). Notably, DPIV results demonstrated that the caudal fin generated multiple wake flow patterns in both the vertical and horizontal planes by varying φ. Vortex jet angle and thrust impulse also varied significantly both in these two planes. In addition, the vortex shedding position along the spanwise tail direction could be shifted around the mid-sagittal position between the upper and lower lobes by changing the phase difference. We hypothesize that the fish caudal fin may serve as a flexible vectoring propeller during swimming and may be critical for the high maneuverability of fish.
Computational modeling and analysis of the hydrodynamics of human swimming

NASA Astrophysics Data System (ADS)

von Loebbecke, Alfred

Computational modeling and simulations are used to investigate the hydrodynamics of competitive human swimming. The simulations employ an immersed boundary (IB) solver that allows us to simulate viscous, incompressible, unsteady flow past complex, moving/deforming three-dimensional bodies on stationary Cartesian grids. This study focuses on the hydrodynamics of the "dolphin kick". Three female and two male Olympic level swimmers are used to develop kinematically accurate models of this stroke for the simulations. A simulation of a dolphin undergoing its natural swimming motion is also presented for comparison. CFD enables the calculation of flow variables throughout the domain and over the swimmer's body surface during the entire kick cycle. The feet are responsible for all thrust generation in the dolphin kick. Moreover, it is found that the down-kick (ventral position) produces more thrust than the up-kick. A quantity of interest to the swimming community is the drag of a swimmer in motion (active drag). Accurate estimates of this quantity have been difficult to obtain in experiments but are easily calculated with CFD simulations. Propulsive efficiencies of the human swimmers are found to be in the range of 11% to 30%. The dolphin simulation case has a much higher efficiency of 55%. Investigation of vortex structures in the wake indicate that the down-kick can produce a vortex ring with a jet of accelerated fluid flowing through its center. This vortex ring and the accompanying jet are the primary thrust generating mechanisms in the human dolphin kick. In an attempt to understand the propulsive mechanisms of surface strokes, we have also conducted a computational analysis of two different styles of arm-pulls in the backstroke and the front crawl. These simulations involve only the arm and no air-water interface is included. Two of the four strokes are specifically designed to take advantage of lift-based propulsion by undergoing lateral motions of the hand (sculling) and by orienting the palm obliquely to the flow. The focus of the current study is on quantifying the relative contributions of drag and lift to thrust production and use this as a basis for determining the relative effectiveness the stroke styles.
Comet Halley and nongravitational forces

NASA Technical Reports Server (NTRS)

Yeomans, D. K.

1977-01-01

The motion of comet Halley is investigated over the 1607-1911 interval. The required nongravitational-force model was found to be most consistent with a rocket-type thrust from the vaporization of water ice in the comet's nucleus. The nongravitational effects are time-independent over the investigated interval.
Flow speed has little impact on propulsive characteristics of oscillating foils

NASA Astrophysics Data System (ADS)

Van Buren, T.; Floryan, D.; Wei, N.; Smits, A. J.

2018-01-01

Experiments are reported on the performance of a pitching and heaving two-dimensional foil in a water channel in either continuous or intermittent motion. We find that the thrust and power are independent of the mean free-stream velocity for twofold changes in the mean velocity (fourfold in the dynamic pressure) and for oscillations in the velocity up to 38% of the mean, where the oscillations are intended to mimic those of freely swimming motions where the thrust varies during the flapping cycle. We demonstrate that the correct velocity scale is not the flow velocity but the mean velocity of the trailing edge. We also find little or no impact of streamwise velocity change on the wake characteristics such as vortex organization, vortex strength, and time-averaged velocity profile development—the wake is both qualitatively and quantitatively unchanged. Our results suggest that constant velocity studies can be used to make robust conclusions about swimming performance without a need to explore the free-swimming condition.
A Randomized Crossover Study Comparing Cervical Spine Motion During Intubation Between Two Lightwand Intubation Techniques in Patients With Simulated Cervical Immobilization: Laryngoscope-Assisted Versus Conventional Lightwand Intubation.

PubMed

Kim, Tae Kyong; Son, Je-Do; Seo, Hyungseok; Lee, Yun-Seok; Bae, Jinyoung; Park, Hee-Pyoung

2017-08-01

In patients with cervical immobilization, jaw thrust can cause cervical spine movement. Concurrent use of a laryngoscope may facilitate lightwand intubation, allowing midline placement and free movement of the lightwand in the oral cavity without jaw thrust. We compared the effects of laryngoscope-assisted lightwand intubation (LALI) versus conventional lightwand intubation (CLI) on cervical spine motion during intubation in patients with simulated cervical immobilization. In this randomized crossover study, the cervical spine angle was measured before and during intubation at the occiput-C1, C1-C2, and C2-C5 segments in 20 patients with simulated cervical immobilization who underwent intubation using both the LALI and CLI techniques. Cervical spine motion was defined as the change from baseline in angle measured at each cervical segment during intubation. Cervical spine motion at the occiput-C1 segment was 5.6° (4.3) and 9.3° (4.5) when we used the LALI and CLI techniques, respectively (mean difference [98.33% CI]; -3.8° [-7.2 to -0.3]; P = .007). At other cervical segments, it was not significantly different between the 2 techniques (-0.1° [-2.6 to 2.5]; P = .911 in the C1-C2 segment and -0.2° [-2.8 to 2.5]; P = .795 in the C2-C5 segment). The LALI technique produces less upper cervical spine motion during intubation than the CLI technique in patients with simulated cervical immobilization.
A globally nonsingular quaternion-based formulation for all-electric satellite trajectory optimization

NASA Astrophysics Data System (ADS)

Libraro, Paola

The general electric propulsion orbit-raising maneuver of a spacecraft must contend with four main limiting factors: the longer time of flight, multiple eclipses prohibiting continuous thrusting, long exposure to radiation from the Van Allen belt and high power requirement of the electric engines. In order to optimize a low-thrust transfer with respect to these challenges, the choice of coordinates and corresponding equations of motion used to describe the kinematical and dynamical behavior of the satellite is of critical importance. This choice can potentially affect the numerical optimization process as well as limit the set of mission scenarios that can be investigated. To increase the ability to determine the feasible set of mission scenarios able to address the challenges of an all-electric orbit-raising, a set of equations free of any singularities is required to consider a completely arbitrary injection orbit. For this purpose a new quaternion-based formulation of a spacecraft translational dynamics that is globally nonsingular has been developed. The minimum-time low-thrust problem has been solved using the new set of equations of motion inside a direct optimization scheme in order to investigate optimal low-thrust trajectories over the full range of injection orbit inclinations between 0 and 90 degrees with particular focus on high-inclinations. The numerical results consider a specific mission scenario in order to analyze three key aspects of the problem: the effect of the initial guess on the shape and duration of the transfer, the effect of Earth oblateness on transfer time and the role played by, radiation damage and power degradation in all-electric minimum-time transfers. Finally trade-offs between mass and cost savings are introduced through a test case.
Lower extremity thrust and non-thrust joint mobilization for patellofemoral pain syndrome: a case report.

PubMed

Simpson, Brad G; Simon, Corey B

2014-05-01

A 40-year old female presented to physical therapy with a one-year history of insidious right anteromedial and anterolateral knee pain. Additionally, the patient had a history of multiple lateral ankle sprains bilaterally, the last sprain occurring on the right ankle 1 year prior to the onset of knee pain. The patient was evaluated and given a physical therapy diagnosis of patellofemoral pain syndrome (PFPS), with associated talocrural and tibiofemoral joint hypomobility limiting ankle dorsiflexion and knee extension, respectively. Treatment included a high-velocity low amplitude thrust manipulation to the talocrural joint, which helped restore normal ankle dorsiflexion range of motion. The patient also received tibiofemoral joint non-thrust manual therapy to regain normal knee extension mobility prior to implementing further functional progression exercises to her home program (HEP). This case report highlights the importance of a detailed evaluation of knee and ankle joint mobility in patients presenting with anterior knee pain. Further, manual physical therapy to the lower extremity was found to be successful in restoring normal movement patterns and pain-free function in a patient with chronic anterior knee pain.
Active Deformation of the Northern Cordillera Observed with GPS

NASA Astrophysics Data System (ADS)

Elliott, J.; Jiang, Y.; Leonard, L. J.; Hyndman, R. D.; Freymueller, J.; Mazzotti, S.

2017-12-01

The Northern Cordillera, which encompasses western Canada and eastern Alaska, is a complex tectonic puzzle. Past terrane accretions, the present collision of the Yakutat block, large-scale plate motions, and past and present glacier change have created a tectonic landscape that includes a major transform system, most of the highest peaks in North America, and far-flung ongoing distributed deformation. We present an updated GPS velocity field as well as a new integrated tectonic block model for the region. The style of deformation varies through the region. Surrounding the Yakutat collision, the model includes a number of small blocks that indicate rotations to the east, north, and west as material moves away from the collisional front. These small blocks also show evidence of internal deformation. Farther from the collisional front, blocks are larger and appear to behave more rigidly. In the south, northwestward motion resulting in a prominent band of coastal shear extends from Vancouver Island to Glacier Bay. In the Arctic, small southeastward motions in Alaska transition to easterly motion in Canada that extends to the Mackenize Mountains near the Cordillera-craton boundary. A number of faults and fault systems accommodate relative Pacific-North America plate motion in the region, although the significant majority is along the Fairweather-Queen Charlotte transform system and the St. Elias fold-and-thrust belt. Along the Fairweather-Queen Charlotte system, the motion is dominantly dextral with increasing oblique transpression to the south corresponding to a change in margin trend. At the northern end of the transform system, motion is distributed onto multiple faults. Roughly 75% of the Fairweather motion is transferred west into the St. Elias fold-and-thrust belt, which accommodates 30 mm/yr of convergence. The remaining 25% is transferred north towards the dextral Denali-Totschunda system. The eastern Denali fault presently plays a minor role in accommodating relative plate motion, with 2-3 mm/yr of transpression. Based on a sequence of earthquakes in May 2017, this motion may be distributed along multiple fault strands.
Determination of Stable-Unstable Regions of the Slosh Motion in Spinning Space Vehicle by Perturbation Technique

NASA Astrophysics Data System (ADS)

Kang, Jai Young

2005-12-01

The objectives of this study are to perform extensive analysis on internal mass motion for a wider parameter space and to provide suitable design criteria for a broader applicability for the class of spinning space vehicles. In order to examine the stability criterion determined by a perturbation method, some numerical simulations will be performed and compared at various parameter points. In this paper, Ince-Strutt diagram for determination of stable-unstable regions of the internal mass motion of the spinning thrusting space vehicle in terms of design parameters will be obtained by an analytical method. Also, phase trajectories of the motion will be obtained for various parameter values and their characteristics are compared.
Kinematics and strain distribution of a thrust-related fold system in the Lewis thrust plate, northwestern Montana (U.S.A.)

NASA Astrophysics Data System (ADS)

Yin, An; Oertel, Gerhard

1993-06-01

In order to understand interactions between motion along thrusts and the associated style of deformation and strain distribution in their hangingwalls, geologic mapping and strain measurements were conducted in an excellently exposed thrust-related fold system in the Lewis thrust plate, northwestern Montana. This system consists of: (1) an E-directed basal thrust (the Gunsight thrust) that has a flat-ramp geometry and a slip of about 3.6 km; (2) an E-verging asymmetric anticline with its nearly vertical forelimb truncated by the basal thrust from below; (3) a 4-km wide fold belt, the frontal fold complex, that lies directly in front of the E-verging anticline; (4) a W-directed bedding-parallel fault (the Mount Thompson fault) that bounds the top of the frontal fold belt and separates it from the undeformed to broadly folded strata above; and (5) regionally developed, W-dipping spaced cleavage. Although the overall geometry of the thrust-related fold system differs from any previously documented fault-related folds, the E-verging anticline itself resembles geometrically a Rich-type fault-bend fold. The observed initial cut-off and fold interlimb angles of this anticline, however, cannot be explained by cross-section balancing models for the development of either a fault-bend fold or a fault propagation fold. Possible origins for the E-verging anticline include (1) the fold initiated as an open fault-bend fold and tightened only later during its emplacement along the basal thrust and (2) the fold started as either a fault-bend or a fault-propagation fold, but simultaneous or subsequent volume change incompatible with any balanced cross-section models altered its shape. Strain in the thrust-related fold system was determined by the preferred orientation of mica and chlorite grains. The direction and magnitude of the post-compaction strain varies from place to place. Strains in the foreclimb of the hangingwall anticline imply bedding-parallel thinning at some localities and thickening at others. This inhomogeneity may be caused by the development of thrusts and folds. Strain in the backlimb of the hangingwall anticline implies bedding-parallel stretching in the thrust transport direction. This could be the effect of bending as the E-verging anticline was tightened and transported across the basal thrust ramp. Strain measured next to the Gunsight thrust again indicates locally varying shortening and extension in the transport direction, perhaps in response to inhomogeneous friction on the fault or else to a history of alternating strain hardening and softening in the basal thrust zone.
Dynamic rupture modeling of the transition from thrust to strike-slip motion in the 2002 Denali fault earthquake, Alaska

USGS Publications Warehouse

Aagaard, Brad T.; Anderson, G.; Hudnut, K.W.

2004-01-01

We use three-dimensional dynamic (spontaneous) rupture models to investigate the nearly simultaneous ruptures of the Susitna Glacier thrust fault and the Denali strike-slip fault. With the 1957 Mw 8.3 Gobi-Altay, Mongolia, earthquake as the only other well-documented case of significant, nearly simultaneous rupture of both thrust and strike-slip faults, this feature of the 2002 Denali fault earthquake provides a unique opportunity to investigate the mechanisms responsible for development of these large, complex events. We find that the geometry of the faults and the orientation of the regional stress field caused slip on the Susitna Glacier fault to load the Denali fault. Several different stress orientations with oblique right-lateral motion on the Susitna Glacier fault replicate the triggering of rupture on the Denali fault about 10 sec after the rupture nucleates on the Susitna Glacier fault. However, generating slip directions compatible with measured surface offsets and kinematic source inversions requires perturbing the stress orientation from that determined with focal mechanisms of regional events. Adjusting the vertical component of the principal stress tensor for the regional stress field so that it is more consistent with a mixture of strike-slip and reverse faulting significantly improves the fit of the slip-rake angles to the data. Rotating the maximum horizontal compressive stress direction westward appears to improve the fit even further.
Varus thrust in women with early medial knee osteoarthritis and its relation with the external knee adduction moment.

PubMed

Mahmoudian, Armaghan; van Dieen, Jaap H; Bruijn, Sjoerd M; Baert, Isabel Ac; Faber, Gert S; Luyten, Frank P; Verschueren, Sabine Mp

2016-11-01

Varus thrust, defined as an abrupt increase of the knee varus angle during weight-bearing in gait, has been shown to be present in patients with moderate to severe knee osteoarthritis and is considered to be one of the risk factors for progression of symptomatic medial knee osteoarthritis. We evaluated the presence and magnitude of varus thrust and its relation with the Knee Adduction Moment in women with early medial knee osteoarthritis, and compared it to that in a group of controls and in a group of subjects with established medial knee osteoarthritis. Twenty-seven women with early medial knee osteoarthritis, 20 women with established medial knee osteoarthritis and 24 asymptomatic controls were evaluated. Varus thrust was estimated as an increase of the knee varus angle during the weight-bearing phase of gait at self-selected speed, assessed by 3D motion analysis. Varus thrust was significantly higher in both early and established osteoarthritis groups compared to the control group (P<0.001), but not different between osteoarthritis groups. While the knee adduction moments were higher than controls only in the established osteoarthritis group, the magnitude of varus thrust was significantly correlated with the second peak knee adduction moment. Higher varus thrust was found both in early and established stages of knee osteoarthritis, suggesting that problems with dynamic stabilization of the knee are present early in the development of knee osteoarthritis. This highlights the necessity of considering dynamic alignment in rehabilitation already in the early stages of the disease. Copyright © 2016 Elsevier Ltd. All rights reserved.
A linear induction motor with a coated conductor superconducting secondary

NASA Astrophysics Data System (ADS)

Chen, Xin; Zheng, Shijun; Li, Jing; Ma, Guang Tong; Yen, Fei

2018-07-01

A linear induction motor system composed of a high-Tc superconducting secondary with close-ended coils made of REBCO coated conductor wire was designed and tested experimentally. The measured thrust, normal force and power loss are presented and explained by combining the flux dynamics inside superconductors with existing linear drive theory. It is found that an inherent capacitive component associated to the flux motion of vortices in the Type-II superconductor reduces the impedance of the coils; from such, the associated Lorentz forces are drastically increased. The resulting breakout thrust of the designed linear motor system was found to be extremely high (up to 4.7 kN/m2) while the associated normal forces only a fraction of the thrust. Compared to its conventional counterparts, high-Tc superconducting secondaries appear to be more feasible for use in maglev propulsion and electromagnetic launchers.
Does Talocrural Joint-Thrust Manipulation Improve Outcomes After Inversion Ankle Sprain?

PubMed

Krueger, Brett; Becker, Laura; Leemkuil, Greta; Durall, Christopher

2015-08-01

Clinical Scenario: Ankle sprains account for roughly 10% of sport-related injuries in the active population. The majority of these injuries occur from excessive ankle inversion, leading to lateral ligamentous injury. In addition to pain and swelling, limitations in ankle range of motion (ROM) and self-reported function are common findings. These limitations are thought to be due in part to loss of mobility in the talocrural joint. Accordingly, some investigators have reported using high-velocity, low-amplitude thrust-manipulation techniques directed at the talocrural joint to address deficits in dorsiflexion (DF) ROM and function. This review was conducted to ascertain the impact of talocrural joint-thrust manipulation (TJM) on DF ROM, self-reported function, and pain in patients with a history of ankle sprain. Focused Clinical Question: In patients with a history of inversion ankle sprain, does TJM improve outcomes in DF ROM, self-reported function, and/or pain?
Moving-base simulation evaluation of thrust margins for vertical landing for the NASA YAV-8B Harrier aircraft

NASA Technical Reports Server (NTRS)

Franklin, James A.; Stortz, Michael W.

1993-01-01

A simulation experiment was conducted on Ames Research Center's Vertical Motion Simulator to evaluate the thrust margin for vertical landing required for the YAV-8B Harrier. Two different levels of ground effect were employed, representing the aircraft with or without lift improvement devices installed. In addition, two different inlet temperature profiles were included to cover a wide range of hot gas ingestion. For each ground effect and hot gas ingestion variant, vertical landings were performed at successively heavier weights, with the pilot assessing the acceptability of the operation in each case. Results are presented as a function of hover weight ratio and a metric of the mean ground effect and ingestion that reflect the increase in thrust margin required to provide acceptable control of sink rate during the descent to touchdown with increasing suck down and hot gas ingestion.

Relative motion of orbiting satellites

NASA Technical Reports Server (NTRS)

Eades, J. B., Jr.

1972-01-01

The relative motion problem is analyzed, as a linearized case, and as a numerically determined solution to provide a time history of the geometries representing the motion state. The displacement history and the hodographs for families of solutions are provided, analytically and graphically, to serve as an aid to understanding this problem area. Linearized solutions to relative motion problems of orbiting particles are presented for the impulsive and fixed thrust cases. Second order solutions are described to enhance the accuracy of prediction. A method was developed to obtain accurate, numerical solutions to the intercept and rendezvous problem; and, special situations are examined. A particular problem related to relative motions, where the motion traces develop a cusp, is examined in detail. This phenomenon is found to be dependent on a particular relationship between orbital eccentricity and the inclination between orbital planes. These conditions are determined, and, example situations are presented and discussed.
A triboelectric motion sensor in wearable body sensor network for human activity recognition.

PubMed

Hui Huang; Xian Li; Ye Sun

2016-08-01

The goal of this study is to design a novel triboelectric motion sensor in wearable body sensor network for human activity recognition. Physical activity recognition is widely used in well-being management, medical diagnosis and rehabilitation. Other than traditional accelerometers, we design a novel wearable sensor system based on triboelectrification. The triboelectric motion sensor can be easily attached to human body and collect motion signals caused by physical activities. The experiments are conducted to collect five common activity data: sitting and standing, walking, climbing upstairs, downstairs, and running. The k-Nearest Neighbor (kNN) clustering algorithm is adopted to recognize these activities and validate the feasibility of this new approach. The results show that our system can perform physical activity recognition with a successful rate over 80% for walking, sitting and standing. The triboelectric structure can also be used as an energy harvester for motion harvesting due to its high output voltage in random low-frequency motion.
Measurement of three-dimensional posture and trajectory of lower body during standing long jumping utilizing body-mounted sensors.

PubMed

Ibata, Yuki; Kitamura, Seiji; Motoi, Kosuke; Sagawa, Koichi

2013-01-01

The measurement method of three-dimensional posture and flying trajectory of lower body during jumping motion using body-mounted wireless inertial measurement units (WIMU) is introduced. The WIMU is composed of three-dimensional (3D) accelerometer and gyroscope of two kinds with different dynamic range and one 3D geomagnetic sensor to adapt to quick movement. Three WIMUs are mounted under the chest, right thigh and right shank. Thin film pressure sensors are connected to the shank WIMU and are installed under right heel and tiptoe to distinguish the state of the body motion between grounding and jumping. Initial and final postures of trunk, thigh and shank at standing-still are obtained using gravitational acceleration and geomagnetism. The posture of body is determined using the 3D direction of each segment updated by the numerical integration of angular velocity. Flying motion is detected from pressure sensors and 3D flying trajectory is derived by the double integration of trunk acceleration applying the 3D velocity of trunk at takeoff. Standing long jump experiments are performed and experimental results show that the joint angle and flying trajectory agree with the actual motion measured by the optical motion capture system.
New Insights into the present-day kinematics of the central and western Papua New Guinea from GPS

NASA Astrophysics Data System (ADS)

Koulali, A.; Tregoning, P.; McClusky, S.; Stanaway, R.; Wallace, L.; Lister, G.

2015-08-01

New Guinea is a region characterized by rapid oblique convergence between the Pacific and Australian tectonic plates. The detailed tectonics of the region, including the partitioning of relative block motions and fault slip rates within this complex boundary plate boundary zone are still not well understood. In this study, we quantify the distribution of the deformation throughout the central and western parts of Papua New Guinea (PNG) using 20 yr of GPS data (1993-2014). We use an elastic block model to invert the regional GPS velocities as well as earthquake slip vectors for the location and rotation rates of microplate Euler poles as well as fault slip parameters in the region. Convergence between the Pacific and the Australian plates is accommodated in northwestern PNG largely by the New Guinea Trench with rates exceeding 90 mm yr-1, indicating that this is the major active interplate boundary. However, some convergent deformation is partitioned into a shear component with ˜12 per cent accommodated by the Bewani-Torricelli fault zone and the southern Highlands Fold-and-Thrust Belt. New GPS velocities in the eastern New Guinea Highlands region have led to the identification of the New Guinea Highlands and the Papuan Peninsula being distinctly different blocks, separated by a boundary through the Aure Fold-and-Thrust Belt complex which accommodates an estimated 4-5 mm yr-1 of left-lateral and 2-3 mm yr-1 of convergent motion. This implies that the Highlands Block is rotating in a clockwise direction relative to the rigid Australian Plate, consistent with the observed transition to left-lateral strike-slip regime observed in western New Guinea Highlands. We find a better fit of our block model to the observed velocities when assigning the current active boundary between the Papuan Peninsula and the South Bismark Block to be to the north of the city of Lae on the Gain Thrust, rather than on the more southerly Ramu-Markham fault as previously thought. This may indicate a temporary shift of activity onto out of sequence thrusts like the Gain Thrust as opposed to the main frontal thrust (the Ramu-Markham fault). In addition, we show that the southern Highlands Fold-and-Thrust Belt is the major boundary between the rigid Australian Plate and the New Guinea Highlands Block, with convergence occurring at rates between ˜6 and 13 mm yr-1.
Motion sickness, console video games, and head-mounted displays.

PubMed

Merhi, Omar; Faugloire, Elise; Flanagan, Moira; Stoffregen, Thomas A

2007-10-01

We evaluated the nauseogenic properties of commercial console video games (i.e., games that are sold to the public) when presented through a head-mounted display. Anecdotal reports suggest that motion sickness may occur among players of contemporary commercial console video games. Participants played standard console video games using an Xbox game system. We varied the participants' posture (standing vs. sitting) and the game (two Xbox games). Participants played for up to 50 min and were asked to discontinue if they experienced any symptoms of motion sickness. Sickness occurred in all conditions, but it was more common during standing. During seated play there were significant differences in head motion between sick and well participants before the onset of motion sickness. The results indicate that commercial console video game systems can induce motion sickness when presented via a head-mounted display and support the hypothesis that motion sickness is preceded by instability in the control of seated posture. Potential applications of this research include changes in the design of console video games and recommendations for how such systems should be used.
Significant strain accumulation between the deformation front and landward out-of-sequence thrusts in accretionary wedge of SW Taiwan revealed by cGPS and SAR interferometry

NASA Astrophysics Data System (ADS)

Tsai, M. C.

2017-12-01

High strain accumulation across the fold-and-thrust belt in Southwestern Taiwan are revealed by the Continuous GPS (cGPS) and SAR interferometry. This high strain is generally accommodated by the major active structures in fold-and-thrust belt of western Foothills in SW Taiwan connected to the accretionary wedge in the incipient are-continent collision zone. The active structures across the high strain accumulation include the deformation front around the Tainan Tableland, the Hochiali, Hsiaokangshan, Fangshan and Chishan faults. Among these active structures, the deformation pattern revealed from cGPS and SAR interferometry suggest that the Fangshan transfer fault may be a left-lateral fault zone with thrust component accommodating the westward differential motion of thrust sheets on both side of the fault. In addition, the Chishan fault connected to the splay fault bordering the lower-slope and upper-slope of the accretionary wedge which could be the major seismogenic fault and an out-of-sequence thrust fault in SW Taiwan. The big earthquakes resulted from the reactivation of out-of-sequence thrusts have been observed along the Nankai accretionary wedge, thus the assessment of the major seismogenic structures by strain accumulation between the frontal décollement and out-of-sequence thrusts is a crucial topic. According to the background seismicity, the low seismicity and mid-crust to mantle events are observed inland and the lower- and upper- slope domain offshore SW Taiwan, which rheologically implies the upper crust of the accretionary wedge is more or less aseimic. This result may suggest that the excess fluid pressure from the accretionary wedge not only has significantly weakened the prism materials as well as major fault zone, but also makes the accretionary wedge landward extension, which is why the low seismicity is observed in SW Taiwan area. Key words: Continuous GPS, SAR interferometry, strain rate, out-of-sequence thrust.
An artificial muscle actuator for biomimetic underwater propulsors.

PubMed

Yim, Woosoon; Lee, Joonsoo; Kim, Kwang J

2007-06-01

In this paper, we introduce the analytical framework of the modeling dynamic characteristics of a soft artificial muscle actuator for aquatic propulsor applications. The artificial muscle used for this underwater application is an ionic polymer-metal composite (IPMC) which can generate bending motion in aquatic environments. The inputs of the model are the voltages applied to multiple IPMCs, and the output can be either the shape of the actuators or the thrust force generated from the interaction between dynamic actuator motions and surrounding water. In order to determine the relationship between the input voltages and the bending moments, the simplified RC model is used, and the mechanical beam theory is used for the bending motion of IPMC actuators. Also, the hydrodynamic forces exerted on an actuator as it moves relative to the surrounding medium or water are added to the equations of motion to study the effect of actuator bending on the thrust force generation. The proposed method can be used for modeling the general bending type artificial muscle actuator in a single or segmented form operating in the water. The segmented design has more flexibility in controlling the shape of the actuator when compared with the single form, especially in generating undulatory waves. Considering an inherent nature of large deformations in the IPMC actuator, a large deflection beam model has been developed and integrated with the electrical RC model and hydrodynamic forces to develop the state space model of the actuator system. The model was validated against existing experimental data.
Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh

2003-01-01

The present NASA GRC-funded three-year research project is focused on studying PDE driven ejectors applicable to a hybrid Pulse Detonation/Turbofan Engine. The objective of the study is to characterize the PDE-ejector thrust augmentation. A PDE-ejector system has been designed to provide critical experimental data for assessing the performance enhancements possible with this technology. Completed tasks include demonstration of a thrust stand for measuring average thrust for detonation tube multi-cycle operation, and design of a 72-in.-long, 2.25-in.-diameter (ID) detonation tube and modular ejector assembly. This assembly will allow testing of both straight and contoured ejector geometries. Initial ejectors that have been fabricated are 72-in.-long-constant-diameter tubes (4-, 5-, and 6-in.-diameter) instrumented with high-frequency pressure transducers. The assembly has been designed such that the detonation tube exit can be positioned at various locations within the ejector tube. PDE-ejector system experiments with gaseous ethylene/ nitrogen/oxygen propellants will commence in the very near future. The program benefits from collaborations with Prof. Merkle of University of Tennessee whose PDE-ejector analysis helps guide the experiments. The present research effort will increase the TRL of PDE-ejectors from its current level of 2 to a level of 3.
Airborne Electro-Mechanical Actuator Test Stand for Development of Prognostic Health Management Systems

DTIC Science & Technology

2010-10-01

based on a pre-defined UH-60 data format, then also computes the load and position profile information. File Profile Interface In order to test the...of the data set. Figure 13 shows a typical motion profile executed over a period of about twenty minutes. Figure 14 shows the desired ( computed ...flight. The stand is connected to the aircraft data bus and the motion profiles for the test actuators, as well as the load applied to them, are
Initial Thrust Measurements of Marshall's Ion-ioN Thruster

NASA Technical Reports Server (NTRS)

Caruso, Natalie R. S.; Scogin, Tyler; Liu, Thomas M.; Walker, Mitchell L. R.; Polzin, Kurt A.; Dankanich, John W.

2015-01-01

Electronegative ion thrusters are a variation of traditional gridded ion thruster technology differentiated by the production and acceleration of both positive and negative ions. Benefits of electronegative ion thrusters include the elimination of lifetime-limiting cathodes from the thruster architecture and the ability to generate appreciable thrust from both charge species. While much progress has been made in the development of electronegative ion thruster technology, direct thrust measurements are required to unambiguously demonstrate the efficacy of the concept and support continued development. In the present work, direct thrust measurements of the thrust produced by the MINT (Marshall's Ion-ioN Thruster) are performed using an inverted-pendulum thrust stand in the High-Power Electric Propulsion Laboratory's Vacuum Test Facility-1 at the Georgia Institute of Technology with operating pressures ranging from 4.8 x 10(exp -5) and 5.7 x 10(exp -5) torr. Thrust is recorded while operating with a propellant volumetric mixture ratio of 5:1 argon to nitrogen with total volumetric flow rates of 6, 12, and 24 sccm (0.17, 0.34, and 0.68 mg/s). Plasma is generated using a helical antenna at 13.56 MHz and radio frequency (RF) power levels of 150 and 350 W. The acceleration grid assembly is operated using both sinusoidal and square waveform biases of +/-350 V at frequencies of 4, 10, 25, 125, and 225 kHz. Thrust is recorded for two separate thruster configurations: with and without the magnetic filter. No thrust is discernable during thruster operation without the magnetic filter for any volumetric flow rate, RF forward Power level, or acceleration grid biasing scheme. For the full thruster configuration, with the magnetic filter installed, a brief burst of thrust of approximately 3.75 mN +/- 3 mN of error is observed at the start of grid operation for a volumetric flow rate of 24 sccm at 350 W RF power using a sinusoidal waveform grid bias at 125 kHz and +/- 350 V. Similar bursts in thrust are observed using a square waveform grid bias at 10 kHz and +/- 350 V for volumetric flow rates of 6, 10, and 12 sccm at 150, 350, and 350 W respectively. The only operating condition that exhibits repeated thrust spikes throughout thruster operation is the 24 sccm condition with a 5:1 mixture ratio at 150 W RF power using the 10 kHz square waveform acceleration grid bias. Thrust spikes for this condition measure 3 mN with an error of +/- 2.5 mN. There are no operating conditions tested that show continuous thrust production.
Performance Evaluation of the T6 Ion Engine

NASA Technical Reports Server (NTRS)

Snyder, John Steven; Goebel, Dan M.; Hofer, Richard R.; Polk, James E.; Wallace, Neil C.; Simpson, Huw

2010-01-01

The T6 ion engine is a 22-cm diameter, 4.5-kW Kaufman-type ion thruster produced by QinetiQ, Ltd., and is baselined for the European Space Agency BepiColombo mission to Mercury and is being qualified under ESA sponsorship for the extended range AlphaBus communications satellite platform. The heritage of the T6 includes the T5 ion thruster now successfully operating on the ESA GOCE spacecraft. As a part of the T6 development program, an engineering model thruster was subjected to a suite of performance tests and plume diagnostics at the Jet Propulsion Laboratory. The engine was mounted on a thrust stand and operated over its nominal throttle range of 2.5 to 4.5 kW. In addition to the typical electrical and flow measurements, an E x B mass analyzer, scanning Faraday probe, thrust vector probe, and several near-field probes were utilized. Thrust, beam divergence, double ion content, and thrust vector movement were all measured at four separate throttle points. The engine performance agreed well with published data on this thruster. At full power the T6 produced 143 mN of thrust at a specific impulse of 4120 seconds and an efficiency of 64%; optimization of the neutralizer for lower flow rates increased the specific impulse to 4300 seconds and the efficiency to nearly 66%. Measured beam divergence was less than, and double ion content was greater than, the ring-cusp-design NSTAR thruster that has flown on NASA missions. The measured thrust vector offset depended slightly on throttle level and was found to increase with time as the thruster approached thermal equilibrium.
A Seismo-Tectonic Signal From Offshore Sedimentation: The 2010 Haiti Earthquake and Prior Events

NASA Astrophysics Data System (ADS)

McHugh, C. M.; Seeber, L.; Cormier, M.; Hornbach, M.; Momplaisir, R.; Waldhauser, F.; Sorlien, C. C.; Steckler, M. S.; Gulick, S.

2011-12-01

The Mw 7.0 January 2010 earthquake in Haiti was one of the deadliest in history. It involved multiple faults along or near the main Enriquillo-Plantain Garden Fault (EPGF). This left-lateral transform is a branch of the northern Caribbean plate boundary across southern Hispaniola. The main rupture was strike-slip but almost all aftershocks had thrust mechanisms, and surface deformation may have been concentrated on anticline forelimbs driven by blind thrust faults. Earthquake generated mass-wasting and turbidity currents were sampled from the Canal du Sud slope (~1000 m water depth), a basin at 1500 m, and the deepest part of the strait at 1700 m. The turbidites were strongly correlated by 234Th with a half-life of 24 days. In the deepest area, a turbidite-homogenite unit (T-H) extends over 50 km2 and is composed of basal sand beds 5 cm thick and 50 cm of mud above. The sedimentary structures in the sand were linked to oscillatory motions by internal seiches. The T-H units recovered from the slope and deep basin are similar in composition. The Leogane Delta, upslope from the sampling sites, is rich in this lithology that has been linked to oceanic basement rocks exposed on the southern Haitian peninsula. In contrast, the T-H unit recovered from the basin at 1500 m is perched behind a thrust anticline and has a greater concentration of Ca derived from Ca rich sources such as the Tapion Ridge on the southern peninsula. The Tapion Ridge is a compressional structure associated with a restraining bend along the EPGF. The T-H unit beneath the 2010 deposit has a 14C age of 2400 cal yrs BP, and interpreted as an earthquake triggered deposit. It is nearly identical in thickness, composition and fine structures to the 2010 T-H. Notably absent from the record are younger turbidites that could have been linked to the historic 1770 AD and other similar earthquakes expected from GPS rates across the EPGF. Two hypotheses are being considered for this long gap in T-H sedimentation. One proposes that during relative high stands of sea level fringing reefs are trapping sediment on the shelf and that a critical accumulation is needed to generate failure. Many large local earthquakes could have occurred before reaching this critical thickness. Low sedimentation rates (6 cm/1000 yrs) support this possibility. Our preferred hypothesis, alternatively, links T-Hs to earthquakes with a large thrust component such as the 2010 event in order to generate failure. This latter hypothesis accounts for some earthquakes producing no turbidites while others, such as the 2010 event, do. It also accounts for the fracturing sampled along 8 km of the perched basin. We propose that thrust earthquakes along the Tapion Ridge segment of the EPGF reoccur at ~2000-year intervals and this sedimentary signal is preserved in Canal du Sud.
Simulator fidelity requirements for airline pilot training and evaluation continued : an update on motion requirements research

DOT National Transportation Integrated Search

2003-04-01

Preliminary results are presented on the effect of enhanced hexapod motion on airline pilot recurrent evaluation, training, and transfer of training to the simulator with motion as a stand-in for the airplane (quasi-transfer). A first study, which te...
Public Diplomacy: How to Think About and Improve It

DTIC Science & Technology

2004-01-01

goals, policies and activities of the U.S. government. The thrust of public affairs is to inform the domestic audience ... [whereas] public di- plomacy...seeks to promote the national interest of the United States through under- standing, informing, and influencing foreign audiences . 7 The semantic...converge more than their definitions imply. The provision of information intended for domestic audiences is frequently received by foreign audiences as
A Comprehensive Toolset for General-Purpose Private Computing and Outsourcing

DTIC Science & Technology

2016-12-08

project and scientific advances made towards each of the research thrusts throughout the project duration. 1 Project Objectives Cloud computing enables...possibilities that the cloud enables is computation outsourcing, when the client can utilize any necessary computing resources for its computational task...Security considerations, however, stand on the way of harnessing the full benefits of cloud computing to the fullest extent and prevent clients from
Saturn Apollo Program

NASA Image and Video Library

1960-01-01

The F-1 engine was developed and built by Rocketdyne under the direction of the Marshall Space Flight Center. It measured 19 feet tall by 12.5 feet at the nozzle exit, and produced a 1,500,000-pound thrust using liquid oxygen and kerosene as the propellant. The image shows an F-1 engine being test fired at the Test Stand 1-C at the Edwards Air Force Base in California.
Development of a Specific Impulse Balance for a Pulsed Capillary Discharge (Preprint)

DTIC Science & Technology

2008-06-13

thrust stand [rad/s] I. Introduction A capillary discharge based coaxial , electrothermal pulsed plasma thruster (PPT) is currently under...20-23 July 2008. 14. ABSTRACT A capillary discharge based pulsed plasma thruster is currently under development at the Air Force Research...Edwards AFB, CA 93524 A capillary discharge based pulsed plasma thruster is currently under development at the Air Force Research Laboratory. A
Minimum Propellant Low-Thrust Maneuvers near the Libration Points

NASA Astrophysics Data System (ADS)

Marinescu, A.; Dumitrache, M.

The impulse technique certainly can bring the vehicle on orbits around the libration points or close to them. The question that aries is, by what means can the vehicle arrive in such cases at the libration points? A first investigation carried out in this paper can give an answer: the use of the technique of low-thrust, which, in addition, can bring the vehicle from the libration points near to or into orbits around these points. This aspect is considered in this present paper where for the applications we have considered the transfer for orbits of the equidistant point L4 and of the collinear point L2, from Earth-moon system. This transfer maneuver can be used to insertion one satellite on libration points orbits. In Earth- moon system the points L 4 and L 5 because an vehicle in on of the equidistant points in quite stable and remains in its vicinity of perturbed, have potential interest for the establishment of transporder satellite for interplanetary tracking. In contrast an vehicle in one of the collinear points is quite instable and it will oscillate along the Earth-moon-axis at increasing amplitude and gradually escape from the libration point. Let use assume that a space vehicle equipped with a low-thrust propulsion is near a libration point L. We consider the planar motion in the restricted frame of the three bodies in the rotating system L, where the Earth-moon distance D=l. The unit of time T is period of the moon's orbit divided by 2 and multiplied by the square root of the quantity one plus the moon/Earth mass ratio, and the unit of mass is the Earth's mass. With these predictions the motion equatios of the vehicle equiped with a low-thrust propulsion installation in the linear approximation near the libration point, have been established. The parameters of the motion at the beginning and the end of these maneuvers are known, the variational problem has been formulated as a Lagrange type problem with fixed extremities. On established the differential equations of the extremals and integrating these differential equations we obtain the desired extremals which characterize the minimum propellant optimal manoeuvres of transfer from libration points to their orbits. By means of Legendre conditions for weak minimum and Weierstrass condition for strong minimum, is demonstrated that variational problem so formulated has sense and is a problem of minimum. The integration of extremal's differential equations system can not lead to analytical solutions easily to obtain and for this we have directed to a numerical integration. The problem is a bilocal one because the motion parameter values are predicted at the beginning and of the maneuver (the manoeuvre duration coincides with the combustion duration) the values of the Lagrange multipliers not being specified at the beginning and end of the manoeuvre. For determination of the velocities at any point on the libration point L4 and L2 has been elaborated the program of calculus on the integration of the motion equations without accelerations due thrust during a revolution period the coordinates and velocities to be equal, with which have been calculated the velocities at the apoapsis A and respectively A'. With these specifications, the final conditions (at the end of the maneuver) could be established, and the determination of optimal transfer parameters in the specified points could be determined. The calculus performed for the transfer from the libration points L4 and L2 to their orbits, shows that the evolution velocities on the orbits are in general small, the velocities on the L2 orbits being greater than the velocities on L 4 orbits having the same semimajor axis. This fact is explicable because the period of evolution on orbits of libration point L4 is greater than the period of orbits of the libration point L2. For the transfer in the apoapsis of both orbits (the points A. and A') on can remarque the fact the accelerations due thrust are greater for orbits around the libration point L2 comparatively with orbits having the same semimajor axis around the libration point L 4 ( maneuver duration = 106 s = 11.574 days for L 4 and = 105 s = 1.157 days for L2 ). Considering orbits around libration points L4 and L2 with semimajor axis between 150-15000 km the components of acceleration due thrust have values between 10-2 -10-5 m/S2 which lays in the range of performances of law thrust propulsion installations (the D, T units have been converted in m, s). *Senior Scientist. Member AIAA **Researche Engineer
Focal Mechanisms From Moment Tensor Solutions and First Motion Polarities of Shallow to Deep Local Earthquakes in Eastern Nepal and Southern Tibet

NASA Astrophysics Data System (ADS)

de La Torre, T. L.; Sheehan, A. F.; Monsalve, G.; Wu, F.

2004-12-01

We determined focal mechanisms using waveforms and first motion polarities from local earthquakes recorded during the Himalayan Nepal Tibet Seismic Experiment (HIMNT). The HIMNT experiment included the deployment of 28 broad band seismometers in eastern Nepal and southern Tibet from September 2001 to April 2003. Using a regional moment tensor method (Ammon and Randall, 2001) and first motion polarities for displaying double-couple focal mechanisms (Snokes, 2003), we analyzed the fault plane solutions at three distinct zones of seismicity. Characteristic focal mechanisms in seismically concentrated areas may indicate the presence of fault ramps or a decollement in the Himalayan collision zone. Previous studies of focal mechanisms on the Tibetan Plateau predominantly indicate east-west extension and shallow thrusting at the Himalayan collision zone for shallow to intermediate earthquakes (Ni and Barazangi, 1984; Molnar and Lyon-Caen, 1989; Randall et al., 1995) and east-west extension for intermediate to deep earthquakes (Zhu and Helmberger, 1996; Chen and Yang, 2004). The first zone in southeast Nepal between the Main Boundary and Main Frontal faults consist of earthquakes < Mw 4.0 at depths 40 - 60 km near the epicenter of the 1988 Udaypur earthquake, Mb 6.1, depth 57 km. The second zone north of the Main Central Thrust outcrop in eastern Nepal consists of 14 earthquakes 3.0 - 5.0 Mw at depths < 30 km that indicate north-south strike normal faulting and east-west strike thrust faulting. The third zone is an arc parallel to the Himalayas in southern Tibet and a cluster in northeast Nepal. This zone consists of 45 earthquakes < 4.0 Mw at depths > 50 km. Four earthquakes indicate northwest-southeast compression resulting in northeast strike strike-slip faulting while one earthquake in the northeast cluster indicates east-west compression at a source depth below the crust-mantle boundary. Focal mechanisms from full waveform moment tensor inversions are cross checked with first motion solutions for selected events. Source depths as determined from normalized error of the sum of the squared differences between the data and synthetic seismogram coincide with the source depths determined from the travel time residual inversion.
Effects of fault dip and slip rake angles on near-source ground motions: Why rupture directivity was minimal in the 1999 Chi-Chi, Taiwan, earthquake

USGS Publications Warehouse

Aagaard, Brad T.; Hall, J.F.; Heaton, T.H.

2004-01-01

We study how the fault dip and slip rake angles affect near-source ground velocities and displacements as faulting transitions from strike-slip motion on a vertical fault to thrust motion on a shallow-dipping fault. Ground motions are computed for five fault geometries with different combinations of fault dip and rake angles and common values for the fault area and the average slip. The nature of the shear-wave directivity is the key factor in determining the size and distribution of the peak velocities and displacements. Strong shear-wave directivity requires that (1) the observer is located in the direction of rupture propagation and (2) the rupture propagates parallel to the direction of the fault slip vector. We show that predominantly along-strike rupture of a thrust fault (geometry similar in the Chi-Chi earthquake) minimizes the area subjected to large-amplitude velocity pulses associated with rupture directivity, because the rupture propagates perpendicular to the slip vector; that is, the rupture propagates in the direction of a node in the shear-wave radiation pattern. In our simulations with a shallow hypocenter, the maximum peak-to-peak horizontal velocities exceed 1.5 m/sec over an area of only 200 km2 for the 30??-dipping fault (geometry similar to the Chi-Chi earthquake), whereas for the 60??- and 75??-dipping faults this velocity is exceeded over an area of 2700 km2 . These simulations indicate that the area subjected to large-amplitude long-period ground motions would be larger for events of the same size as Chi-Chi that have different styles of faulting or a deeper hypocenter.

Comparative kinematics of the forelimb during swimming in red-eared slider (Trachemys scripta) and spiny softshell (Apalone spinifera) turtles.

PubMed

Pace, C M; Blob, R W; Westneat, M W

2001-10-01

Softshell turtles (Family Trionychidae) possess extensive webbing between the digits of the manus, suggesting that the forelimb may serve as an effective thrust generator during aquatic locomotion. However, the hindlimb has previously been viewed as the dominant propulsive organ in swimming freshwater turtles. To evaluate the potential role of the forelimb in thrust production during swimming in freshwater turtles, we compared the forelimb morphology and three-dimensional forelimb kinematics of a highly aquatic trionychid turtle, the spiny softshell Apalone spinifera, and a morphologically generalized emydid turtle, the red-eared slider Trachemys scripta. Spiny softshells possess nearly twice as much forelimb surface area as sliders for generating drag-based thrust. In addition, although both species use drag-based propulsion, several aspects of forelimb kinematics differ significantly between these species. During the thrust phase of the forelimb cycle, spiny softshells hold the elbow and wrist joints significantly straighter than sliders, thereby further increasing the surface area of the limb that can move water posteriorly and increasing the velocity of the distal portion of the forelimb. These aspects of swimming kinematics in softshells should increase forelimb thrust production and suggest that the forelimbs make more substantial contributions to forward thrust in softshell turtles than in sliders. Spiny softshells also restrict forelimb movements to a much narrower dorsoventral and anteroposterior range than sliders throughout the stroke, thereby helping to minimize limb movements potentially extraneous to forward thrust production. These comparisons demonstrate considerable diversity in the forelimb kinematics of turtles that swim using rowing motions of the limbs and suggest that the evolution of turtle forelimb mechanics produced a variety of contrasting solutions for aquatic specialization.
Space Shuttle Projects

NASA Image and Video Library

1976-01-01

This image illustrates the solid rocket motor (SRM)/solid rocket booster (SRB) configuration. The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the SRM's were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment. The boosters are designed to survive water impact at almost 60 miles per hour, maintain flotation with minimal damage, and preclude corrosion of the hardware exposed to the harsh seawater environment. Under the project management of the Marshall Space Flight Center, the SRB's are assembled and refurbished by the United Space Boosters. The SRM's are provided by the Morton Thiokol Corporation.
Multiply charged ion generation according to magnetic field configurations in Hall thruster plasmas

NASA Astrophysics Data System (ADS)

Kim, Holak; Lee, Seunghun; Kim, Junbum; Lim, Youbong; Choe, Wonho; KIMS Collaboration

2016-09-01

Plasma propulsion is the most promising techniques to operate satellites for low earth orbit as well as deep space exploration. A typical plasma propulsion system is Hall thruster (HT) that uses crossed electromagnetic fields to ionize a propellant gas and to accelerate the ionized gas. In HT the tailoring of magnetic fields is significant due to that the electron confinement in the electromagnetic fields affects thruster performances such as thrust force, specific impulse, power efficiency, and life time. We designed an anode layer HT (TAL) with the magnetic field tailoring. The TAL is possible to keep discharge in 1 2 kilovolts, which voltage is useful to obtain high specific impulse The magnetic field tailoring is adapted to minimize undesirable heat dissipations and secondary electron emissions at a wall surrounding plasma In presentation, we will report TAL performances including thrust force, specific impulse, and anode efficiency measured by a pendulum thrust stand. This mechanical measurement will be compared to the plasma diagnostics conducted by angular Faraday probe, retarding potential analyzer, and ExB probe Grant No. 2014M1A3A3A02034510.
Effect of Propeller Angle Relative to Flow on Aerodynamic Characteristics

NASA Astrophysics Data System (ADS)

Schueller, Joseph; Hubner, Paul

2017-11-01

As the interest in small unmanned air systems (UASs) for delivery and surveillance grows, new hybrid designs are being studied to take advantage of both quadcopters and fixed-wing aircraft. The tiltrotor design is able to combine the vertical take-off, hover, and landing of a multi-rotor copter with the efficiency of forward flight of a conventional airplane. However, literature documenting aerodynamic performance of the rotor as it rotates between the forward-flight and hover positions, especially in this low Reynolds number range, is limited. This data is critical for validating computational models and developing safe transition corridors. The objective of this research was to design, build and test a rotor thrust stand capable of rotating between the forward-flight and hover configurations suitable for senior design studies at low Reynolds number research. The poster covers the design of the rotating mechanism, the range and resolution of the load cell, and the thrust, torque and efficiency results for a conventional UAS motor and propeller for various advance ratios and thrust-line orientations. NSF Grant: EEC 1659710.
Ball motion and sliding friction in an arched outer-race ball bearing

NASA Technical Reports Server (NTRS)

Hamrock, B. J.

1974-01-01

The motion of the ball and sliding friction in an arched outer-race ball bearing under thrust load is analyzed. Fatigue life evaluations were made. The analysis is applied to a 150-millimeter-bore ball bearing. The results indicated that for high-speed light-load applications the arched bearing has significant improvement in fatigue life over that of a conventional bearing. An arching of 0.254 mm (0.01 in.) was found to be optimal. Also, for an arched bearing a considerable amount of spinning occurs at the outer-race contacts.
Hybrid Rocket Experiment Station for Capstone Design

NASA Technical Reports Server (NTRS)

Conley, Edgar; Hull, Bethanne J.

2012-01-01

Portable hybrid rocket motors and test stands can be seen in many papers but none have been reported on the design or instrumentation at such a small magnitude. The design of this hybrid rocket and test stand is to be small and portable (suitcase size). This basic apparatus will be used for demonstrations in rocket propulsion. The design had to include all of the needed hardware to operate the hybrid rocket unit (with the exception of the external Oxygen tank). The design of this project includes making the correlation between the rocket's thrust and its size, the appropriate transducers (physical size, resolution, range, and cost), compatability with a laptop analog card, the ease of setup, and its portability.
Fault Dating in the US Rockies and Large Regional Extent of Deformation Pulses Along the Sevier Orogen of North America.

NASA Astrophysics Data System (ADS)

van der Pluijm, B.; Lynch, E. A.; Pana, D.; Yonkee, A.

2017-12-01

Recent Ar dating of clay-rich fault rock in the Canadian Rockies identified multiple orogenic pulses: Late Jurassic (163-146 Ma), Mid-Cretaceous (103-99 Ma), Late Cretaceous (76-72 Ma) and Eocene (54-52 Ma; Pana and van der Pluijm, GSAB 2015). New dating in the US Rockies combined with ages in the most frontal section along an Idaho-Wyoming transect show a remarkably similar age pattern: Meade Thrust, 108-102 Ma; (S)Absaroka Thrust, 73 Ma; Darby-Bear Thrust, 56-50 Ma. These radiometric fault ages in the US Rockies match field and tectono-stratigraphic predictions, analogues to those in the Canadian Rockies. Thus, a remarkably long (>1500km) lateral tract along the North American Sevier orogen is characterized by at least three major orogenic pulses that are structurally contiguous. These orogenic pulses are progressively younger in the direction of easterly thrust fault motion (toward cratonic interior) and are separated by long periods of relative tectonic quiescence. We interpret the extensive regional continuity of deformation pulses and tectonic quiescence along the Sevier Orogen as the result of three plate reorganization events in western North America since the Late Jurassic.
Lower extremity thrust and non-thrust joint mobilization for patellofemoral pain syndrome: a case report

PubMed Central

Simpson, Brad G; Simon, Corey B

2014-01-01

A 40-year old female presented to physical therapy with a one-year history of insidious right anteromedial and anterolateral knee pain. Additionally, the patient had a history of multiple lateral ankle sprains bilaterally, the last sprain occurring on the right ankle 1 year prior to the onset of knee pain. The patient was evaluated and given a physical therapy diagnosis of patellofemoral pain syndrome (PFPS), with associated talocrural and tibiofemoral joint hypomobility limiting ankle dorsiflexion and knee extension, respectively. Treatment included a high-velocity low amplitude thrust manipulation to the talocrural joint, which helped restore normal ankle dorsiflexion range of motion. The patient also received tibiofemoral joint non-thrust manual therapy to regain normal knee extension mobility prior to implementing further functional progression exercises to her home program (HEP). This case report highlights the importance of a detailed evaluation of knee and ankle joint mobility in patients presenting with anterior knee pain. Further, manual physical therapy to the lower extremity was found to be successful in restoring normal movement patterns and pain-free function in a patient with chronic anterior knee pain. PMID:24976753
To flap or not to flap: a discussion between a fish and a jellyfish

NASA Astrophysics Data System (ADS)

Martin, Nathan; Roh, Chris; Idrees, Suhail; Gharib, Morteza

2016-11-01

Fish and jellyfish are known to swim by flapping and by periodically contracting respectively, but which is the more effective propulsion mechanism? In an attempt to answer this question, an experimental comparison is made between simplified versions of these motions to determine which generates the greatest thrust for the least power. The flapping motion is approximated by pitching plates while periodic contractions are approximated by clapping plates. A machine is constructed to operate in either a flapping or a clapping mode between Reynolds numbers 1,880 and 11,260 based on the average plate tip velocity and span. The effect of the total sweep angle, total sweep time, plate flexibility, and duty cycle are investigated. The average thrust generated and power required per cycle are compared between the two modes when their total sweep angle and total sweep time are identical. In general, operating in the clapping mode required significantly more power to generate a similar thrust compared to the flapping mode. However, modifying the duty cycle for clapping caused the effectiveness to approach that of flapping with an unmodified duty cycle. These results suggest that flapping is the more effective propulsion mechanism within the range of Reynolds numbers tested. This work was supported by the Charyk Bio-inspired Laboratory at the California Institute of Technology, the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469, and the Summer Undergraduate Research Fellowships program.
Chipping whole trees for fuel chips: a production study

Treesearch

Dana Mitchell; Tom Gallagher

2007-01-01

A time and motion study was conducted to determine the productivity and cost of an in-woods chipping operation when processing whole mall-diameter trees for biomass. The study removed biomass from two overstocked stands and compared the cost of this treatment to existing alternatives. The treatment stands consisted of a 30-year-old longleaf pine stand and a 37-year-old...
Active tectonics and strain partitioning along dextral fault system in Central Iran: Analysis of geomorphological observations and geophysical data in the Kashan region

NASA Astrophysics Data System (ADS)

Jamali, Farshad; Hessami, Khaled; Ghorashi, Manoochehr

2011-03-01

This paper uses high-resolution images and field investigations, in conjunction with seismic reflection data, to constrain active structural deformation in the Kashan region of Central Iran. Offset stream beds and Qanats indicate right-lateral strike slip motion at a rate of about 2 mm/yr along the NW-SE trending Qom-Zefreh fault zone which has long been recognized as one of the major faults in Central Iran. However, the pattern of drainage systems across the active growing folds including deep incision of stream beds and deflected streams indicate uplift at depth on thrust faults dipping SW beneath the anticlines. Therefore, our studies in the Kashan region indicate that deformation occurs within Central Iran which is often considered to behave as a non-deforming block within the Arabia-Eurasia collision zone. The fact that the active Qom-Zefreh strike-slip fault runs parallel to the active folds, which overlie blind thrust faults, suggests that oblique motion of Arabia with respect to Eurasia is partitioned in this part of Central Iran.
Flowfield measurements in the wake of a robotic lamprey

PubMed Central

Hultmark, Marcus; Leftwich, Megan

2009-01-01

Experiments are reported on the hydrodynamics of a swimming robotic lamprey under conditions of steady swimming and where the thrust exceeds the drag. The motion of the robot was based on the swimming of live lampreys, which is described by an equation similar to that developed for the American eel by Tytell and Lauder (J Exp Biol 207:1825–1841, 2004). For steady swimming, the wake structure closely resembles that of the American eel, where two pairs of same sign vortices are shed each tail beat cycle, giving the wake a 2P structure. Force estimates suggest that the major part of the thrust is produced at or close to the end of the tail. PMID:19946623
Re-Thinking the Use of the OML Model in Electric-Sail Development

NASA Technical Reports Server (NTRS)

Stone, Nobie H.

2016-01-01

The Orbit Motion Limited (OML) model commonly forms the basis for calculations made to determine the effect of the long, biased wires of an Electric Sail on solar wind protons and electrons (which determines the thrust generated and the required operating power). A new analysis of the results of previously conducted ground-based experimental studies of spacecraft-space plasma interactions indicate that the expected thrust created by deflected solar wind protons and the current of collected solar wind electrons could be considerably higher than the OML model would suggest. Herein the experimental analysis will be summarized and the assumptions and approximations required to derive the OML equation-and the limitations they impose-will be considered.
Streaming and particle motion in acoustically-actuated leaky systems

NASA Astrophysics Data System (ADS)

Nama, Nitesh; Barnkob, Rune; Jun Huang, Tony; Kahler, Christian; Costanzo, Francesco

2017-11-01

The integration of acoustics with microfluidics has shown great promise for applications within biology, chemistry, and medicine. A commonly employed system to achieve this integration consists of a fluid-filled, polymer-walled microchannel that is acoustically actuated via standing surface acoustic waves. However, despite significant experimental advancements, the precise physical understanding of such systems remains a work in progress. In this work, we investigate the nature of acoustic fields that are setup inside the microchannel as well as the fundamental driving mechanism governing the fluid and particle motion in these systems. We provide an experimental benchmark using state-of-art 3D measurements of fluid and particle motion and present a Lagrangian velocity based temporal multiscale numerical framework to explain the experimental observations. Following verification and validation, we employ our numerical model to reveal the presence of a pseudo-standing acoustic wave that drives the acoustic streaming and particle motion in these systems.
Laser-heated rocket thruster

NASA Technical Reports Server (NTRS)

Shoji, J. M.

1977-01-01

A space vehicle application using 5,000-kw input laser power was conceptually evaluated. A detailed design evaluation of a 10-kw experimental thruster including plasma size, chamber size, cooling, and performance analyses, was performed for 50 psia chamber pressure and using hydrogen as a propellant. The 10-kw hardware fabricated included a water cooled chamber, an uncooled copper chamber, an injector, igniters, and a thrust stand. A 10-kw optical train was designed.
45. Historic photo of Building 202 test cell interior, with ...

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

45. Historic photo of Building 202 test cell interior, with engine mounted on test stand A. Close-up view of a twenty-thousand-pound-thrust engine being tested in relation with combustion oscillation studies, October 12, 1960. On file at NASA Plumbrook Research Center, Sandusky, Ohio. NASA photo number C-54595. - Rocket Engine Testing Facility, GRC Building No. 202, NASA Glenn Research Center, Cleveland, Cuyahoga County, OH
SparkJet Actuators for Flow Control

DTIC Science & Technology

2007-03-01

volume. The ceramic component is inserted between a stainless steel holder and a threaded brass cap with a jewel orifice installed in the face (Fig. 3...single sheet of stainless steel shim stock. This metal structure is oriented vertically and clamped at the top and bottom in a Lexan® fixture. The...Laser interferometer arrangement for measuring thrust stand vibrations. In addition to a high natural frequency, the rigid design of the steel
Saturn Apollo Program

NASA Image and Video Library

1965-03-01

S-IB-1, the first flight version of the Saturn IB launch vehicle's first stage (S-IB stage), sat in the Marshall Space Flight Center (MSFC) Saturn IB static test stand on March 15, 1965. Developed by the MSFC and built by the Chrysler Corporation at the Michoud Assembly Facility (MAF) in New Orleans, Louisiana, the 90,000-pound booster utilized eight H-1 engines to produce a combined thrust of 1,600,000 pounds.
Structural dynamics and aerodynamics measurements of biologically inspired flexible flapping wings.

PubMed

Wu, P; Stanford, B K; Sällström, E; Ukeiley, L; Ifju, P G

2011-03-01

Flapping wing flight as seen in hummingbirds and insects poses an interesting unsteady aerodynamic problem: coupling of wing kinematics, structural dynamics and aerodynamics. There have been numerous studies on the kinematics and aerodynamics in both experimental and computational cases with both natural and artificial wings. These studies tend to ignore wing flexibility; however, observation in nature affirms that passive wing deformation is predominant and may be crucial to the aerodynamic performance. This paper presents a multidisciplinary experimental endeavor in correlating a flapping micro air vehicle wing's aeroelasticity and thrust production, by quantifying and comparing overall thrust, structural deformation and airflow of six pairs of hummingbird-shaped membrane wings of different properties. The results show that for a specific spatial distribution of flexibility, there is an effective frequency range in thrust production. The wing deformation at the thrust-productive frequencies indicates the importance of flexibility: both bending and twisting motion can interact with aerodynamic loads to enhance wing performance under certain conditions, such as the deformation phase and amplitude. By measuring structural deformations under the same aerodynamic conditions, beneficial effects of passive wing deformation can be observed from the visualized airflow and averaged thrust. The measurements and their presentation enable observation and understanding of the required structural properties for a thrust effective flapping wing. The intended passive responses of the different wings follow a particular pattern in correlation to their aerodynamic performance. Consequently, both the experimental technique and data analysis method can lead to further studies to determine the design principles for micro air vehicle flapping wings.
Spinal manipulation force and duration affect vertebral movement and neuromuscular responses.

PubMed

Colloca, Christopher J; Keller, Tony S; Harrison, Deed E; Moore, Robert J; Gunzburg, Robert; Harrison, Donald D

2006-03-01

Previous study in human subjects has documented biomechanical and neurophysiological responses to impulsive spinal manipulative thrusts, but very little is known about the neuromechanical effects of varying thrust force-time profiles. Ten adolescent Merino sheep were anesthetized and posteroanterior mechanical thrusts were applied to the L3 spinous process using a computer-controlled, mechanical testing apparatus. Three variable pulse durations (10, 100, 200 ms, force = 80 N) and three variable force amplitudes (20, 40, 60 N, pulse duration = 100 ms) were examined for their effect on lumbar motion response (L3 displacement, L1, L2 acceleration) and normalized multifidus electromyographic response (L3, L4) using a repeated measures analysis of variance. Increasing L3 posteroanterior force amplitude resulted in a fourfold linear increase in L3 posteroanterior vertebral displacement (p < 0.001) and adjacent segment (L1, L2) posteroanterior acceleration response (p < 0.001). L3 displacement was linearly correlated (p < 0.001) to the acceleration response over the 20-80 N force range (100 ms). At constant force, 10 ms thrusts resulted in nearly fivefold lower L3 displacements and significantly increased segmental (L2) acceleration responses compared to the 100 ms (19%, p = 0.005) and 200 ms (16%, p = 0.023) thrusts. Normalized electromyographic responses increased linearly with increasing force amplitude at higher amplitudes and were appreciably affected by mechanical excitation pulse duration. Changes in the biomechanical and neuromuscular response of the ovine lumbar spine were observed in response to changes in the force-time characteristics of the spinal manipulative thrusts and may be an underlying mechanism in related clinical outcomes.

A mechanism of thrust enhancement on a heaving plate due to flexibility at moderately low Reynolds numbers

NASA Astrophysics Data System (ADS)

Lin, Yung-Sheng; Tzeng, Yau-Ting; Chang, Chien-Cheng; Chu, Chin-Chou

2017-11-01

A numerical study is conducted to investigate the force mechanisms for a 3D heaving flexible plate from the perspective of a diagnostic force element analysis (Chang 1992). The problem is relevant to a simplified flapping fish-tail with the front edge held fixed in space. The flow is assumed to be laminar with the Reynolds numbers fixed at Re =200 or 500, and the Strouhal number St ranging from 0.1 to 0.6, and the flexure amplitude of the plate a0 for 0.1 to 0.25 (dimensionless). It is shown that heaving, whilst increasing thrust generation, also reduces the frictional drag, yet the flexibility promotes thrust generation at the expense of accruing more frictional drag. In the literature, the thrust exerted on the tail-mimicking plate is largely credited to the vortices in the wake. However, this study performs a regional force analysis to show that the vorticity in the wake region supplies approximately 20-30% of the total thrust, especially in the cases of strong thrust generation. Comparable contributions come also from the regions direct above and below the heaving plate (mainly including the attached vortices) as well as from the two side regions (mainly including the tip vortices) next to the flapping plate. In addition, the potential motion associated with the unsteady flapping and the contribution from the surface vorticity are non-negligible constituent force components. MOST, TAIWAN under Contacts NO. 105-2221-E-002-097-MY3 and NO. 105-2221-E-002 -105 -MY3.
Active arc-continent collision: Earthquakes, gravity anomalies, and fault kinematics in the Huon-Finisterre collision zone, Papua New Guinea

NASA Astrophysics Data System (ADS)

Abers, Geoffrey A.; McCaffrey, Robert

1994-04-01

The Huon-Finisterre island arc terrane is actively colliding with the north edge of the Australian continent. The collision provides a rare opportunity to study continental accretion while it occurs. We examine the geometry and kinematics of the collision by comparing earthquake source parameters to surface fault geometries and plate motions, and we constrain the forces active in the collision by comparing topographic loads to gravity anomalies. Waveform inversion is used to constrain focal mechanisms for 21 shallow earthquakes that occurred between 1966 and 1992 (seismic moment 1017 to 3 × 1020 N m). Twelve earthquakes show thrust faulting at 22-37 km depth. The largest thrust events are on the north side of the Huon Peninsula and are consistent with slip on the Ramu-Markham thrust fault zone, the northeast dipping thrust fault system that bounds the Huon-Finisterre terrane. Thus much of the terrane's crust but little of its mantle is presently being added to the Australian continent. The large thrust earthquakes also reveal a plausible mechanism for the uplift of Pleistocene coral terraces on the north side of the Huon Peninsula. Bouguer gravity anomalies are too negative to allow simple regional compensation of topography and require large additional downward forces to depress the lower plate beneath the Huon Peninsula. With such forces, plate configurations are found that are consistent with observed gravity and basin geometry. Other earthquakes give evidence of deformation above and below the Ramu-Markham thrust system. Four thrust events, 22-27 km depth directly below the Ramu-Markham fault outcrop, are too deep to be part of a planar Ramu-Markham thrust system and may connect to the north dipping Highlands thrust system farther south. Two large strike-slip faulting earthquakes and their aftershocks, in 1970 and 1987, show faulting within the upper plate of the thrust system. The inferred fault planes show slip vectors parallel to those on nearby thrust faults, and may represent small offsets in the overriding plate. These faults, along with small normal-faulting earthquakes beneath the Huon-Finisterre ranges and a 25° along-strike rotation of slip vectors, demonstrate the presence of along-strike extension of the accreting terrane and along-strike compression of the lower plate.
Drag reduction and thrust generation by tangential surface motion in flow past a cylinder

NASA Astrophysics Data System (ADS)

Mao, Xuerui; Pearson, Emily

2018-03-01

Sensitivity of drag to tangential surface motion is calculated in flow past a circular cylinder in both two- and three-dimensional conditions at Reynolds number Re ≤ 1000 . The magnitude of the sensitivity maximises in the region slightly upstream of the separation points where the contour lines of spanwise vorticity are normal to the cylinder surface. A control to reduce drag can be obtained by (negatively) scaling the sensitivity. The high correlation of sensitivities of controlled and uncontrolled flow indicates that the scaled sensitivity is a good approximation of the nonlinear optimal control. It is validated through direct numerical simulations that the linear range of the steady control is much higher than the unsteady control, which synchronises the vortex shedding and induces lock-in effects. The steady control injects angular momentum into the separating boundary layer, stabilises the flow and increases the base pressure significantly. At Re=100 , when the maximum tangential motion reaches 50% of the free-stream velocity, the vortex shedding, boundary-layer separation and recirculation bubbles are eliminated and 32% of the drag is reduced. When the maximum tangential motion reaches 2.5 times of the free-stream velocity, thrust is generated and the power savings ratio, defined as the ratio of the reduced drag power to the control input power, reaches 19.6. The mechanism of drag reduction is attributed to the change of the radial gradient of spanwise vorticity (partial r \\hat{ζ } ) and the subsequent accelerated pressure recovery from the uncontrolled separation points to the rear stagnation point.
Closing of the Midcontinent-Rift - a far-field effect on Grenvillian compression

USGS Publications Warehouse

Cannon, W.F.

1994-01-01

The Midcontinent rift formed in the Laurentian supercontinent between 1109 and 1094 Ma. Soon after rifting, stresses changed from extensional to compressional, and the central graben of the rift was partly inverted by thrusting on original extensional faults. Thrusting culminated at about 1060 Ma but may have begun as early as 1080 Ma. On the southwest-trending arm of the rift, the crust was shortened about 30km; on the southeast-trending arm, strike-slip motion was dominant. The rift developed adjacent to the tectonically active Grenville province, and its rapid evolution from an extensional to a compressional feature at c1080 Ma was coincident with renewal of northwest-directed thrusting in the Grenville, probably caused by continent-continent collision. A zone of weak lithosphere created by rifting became the locus for deformation within the otherwise strong continental lithosphere. Stresses transmitted from the Grenville province utilized this weak zone to close and invert the rift. -Author
Criteria for design of integrated flight/propulsion control systems for STOVL fighter aircraft

NASA Technical Reports Server (NTRS)

Franklin, James A.

1993-01-01

As part of NASA's program to develop technology for short takeoff and vertical landing (STOVL) fighter aircraft, control system designs have been developed for a conceptual STOVL aircraft. This aircraft is representative of the class of mixed-flow remote-lift concepts that was identified as the preferred design approach by the U.S./U.K. STOVL Joint Assessment and Ranking Team. The control system designs have been evaluated throughout the powered-lift flight envelope on the Vertical Motion Simulator (VMS) at Ames Research Center. Items assessed in the control system evaluation were: maximum control power used in transition and vertical flight, control system dynamic response associated with thrust transfer for attitude control, thrust margin in the presence of ground effect and hot-gas ingestion, and dynamic thrust response for the engine core. Effects of wind, turbulence, and ship airwake disturbances are incorporated in the evaluation. Results provide the basis for a reassessment of existing flying-qualities design criteria applied to STOVL aircraft.
Design criteria for integrated flight/propulsion control systems for STOVL fighter aircraft

NASA Technical Reports Server (NTRS)

Franklin, James A.

1993-01-01

As part of NASA's program to develop technology for short takeoff and vertical landing (STOVL) fighter aircraft, control system designs have been developed for a conceptual STOVL aircraft. This aircraft is representative of the class of mixed-flow remote-lift concepts that was identified as the preferred design approach by the US/UK STOVL Joint Assessment and Ranking Team. The control system designs have been evaluated throughout the powered-lift flight envelope on Ames Research Center's Vertical Motion Simulator. Items assessed in the control system evaluation were: maximum control power used in transition and vertical flight, control system dynamic response associated with thrust transfer for attitude control, thrust margin in the presence of ground effect and hot gas ingestion, and dynamic thrust response for the engine core. Effects of wind, turbulence, and ship airwake disturbances are incorporated in the evaluation. Results provide the basis for a reassessment of existing flying qualities design criteria applied to STOVL aircraft.
Transient Simulation of Pressure Oscillations in the Fuel Feedline of the Fastrac Engine Thrust Chamber

NASA Technical Reports Server (NTRS)

Bullard, Brad

1998-01-01

During mainstage testing of the 60,000 lbf thrust Fastrac thrust chamber at MSFC's Test Stand 116 (TS 116), sustained, large amplitude oscillations near 530 Hz were observed in the pressure data. These oscillations were detected both in the RP-1 feedline, downstream of the cavitating venturi, and in the combustion chamber. The driver of the instability is believed to be feedline excitation driven by either periodic cavity collapse at the exit of the cavitating venturi or combustion instability. In covitating venturi, static pressure drops as the flow passes through a constriction resembling a converging-diverging nozzle until the vapor pressure is reached. At the venturi throat, the flow is essentially choked, which is why these devices are typically used for mass flow rate control and disturbance isolation. Typically, a total pressure drop of 15% or more across the venturi is required for cavitation. For much larger pressure differentials, unstable cavities can form and subsequently collapse downstream of the throat. Although the disturbances generated by cavitating venturis is generally considered to be broad-band, this type of phenomena could generate periodic behavior capable of exciting the feedline. An excitation brought about by combustion instability would result from the coupling of a combustion chamber acoustic mode and a feedline resonance frequency. This type of coupling is referred to as "buzz" and is not uncommon for engines in this thrust range.
Long-distance longitudinal transport of gravel across the Cordilleran thrust belt of Montana and Idaho

NASA Astrophysics Data System (ADS)

Janecke, Susanne U.; Vandenburg, Colby J.; Blankenau, James J.; M'gonigle, John W.

2000-05-01

Two newly identified middle Eocene paleovalleys (≥ 100 km long) preserved on top of the southwest Montana reentrant of the Cordilleran fold-and-thrust belt indicate long-lived longitudinal flow across the thrust belt and resolve a long-standing debate about the source of the voluminous quartzite debris in the Upper Cretaceous to lower Tertiary Divide, Harebell, and Pinyon conglomerates of Montana, Idaho, and Wyoming. Geologic mapping, stratigraphic, provenance, and geochronologic studies revealed that Eocene volcanic and sedimentary rocks in the paleovalleys are as thick as 2 km, onlap preexisting bedrock, and interfinger with well-rounded conglomerate derived from formations exposed only to the west. The middle Eocene paleovalleys are the youngest expression of a major paleoriver system that transported sediment toward the foreland during the Sevier orogeny. An Eocene subcrop map shows that the headwaters of the Eocene paleovalleys coincided with structural culminations in the thrust belt that supplied sediment to the Divide conglomerate of the Upper Cretaceous to lower Tertiary Beaverhead Group. Ultimately, the Lemhi Pass and Hawley Creek paleovalleys provided several thousand cubic kilometers of quartzite debris to the Pinyon and Harebell conglomerates of northwest Wyoming 200 350 km away, and formed the northwest half of a giant longitudinal drainage system. Sevier contraction, not the rising Idaho batholith, first uplifted vast culminations beneath the headwaters of this river system.
H2 arcjet performance mapping program

NASA Astrophysics Data System (ADS)

1992-01-01

Work performed during the period of Mar. 1991 to Jan. 1992 is reviewed. High power H2 arcjets are being considered for electric powered orbit transfer vehicles (EOTV). Mission analyses indicate that the overall arcjet thrust efficiency is very important since increasing the efficiency increases the thrust, and thereby reduces the total trip time for the same power. For example, increasing the thrust efficiency at the same specific impulse from 30 to 40 percent will reduce the trip time by 25 percent. For a 200 day mission, this equates to 50 days, which results in lower ground costs and less time during which the payload is dormant. Arcjet performance levels of 1200 seconds specific impulse (lsp) at 35 to 40 percent efficiency with lifetimes over 1000 hours are needed to support EOTV missions. Because of the potential very high efficiency levels, the objective of this program was to evaluate the ability of a scaled Giannini-style thruster to achieve the performance levels while operating at a reduced nominal power of 10 kW. To meet this objective, a review of past literature was conducted; scaling relationships were developed and applied to establish critical dimensions; a development thruster was designed with the aid of the plasma analysis model KARNAC and finite element thermal modeling; test hardware was fabricated; and a series of performance tests were conducted in RRC's Cell 11 vacuum chamber with its null-balance thrust stand.
Kinematics of the active West Andean fold-and-thrust belt (central Chile): Structure and long-term shortening rate

NASA Astrophysics Data System (ADS)

Riesner, M.; Lacassin, R.; Simoes, M.; Armijo, R.; Rauld, R.; Vargas, G.

2017-02-01

West verging thrusts, synthetic with the Nazca-South America subduction interface, have been recently discovered at the western front of the Andes. At 33°30'S, the active San Ramón fault stands as the most frontal of these west verging structures and represents a major earthquake threat for Santiago, capital city of Chile. Here we elaborate a detailed 3-D structural map and a precise cross section of the West Andean fold-and-thrust belt based on field observations, satellite imagery, and previous structural data, together with digital topography. We then reconstruct the evolution of this frontal belt using a trishear kinematic approach. Our reconstruction implies westward propagation of deformation with a total shortening of 9-15 km accumulated over the last 25 Myr. An overall long-term shortening rate of 0.1-0.5 mm/yr is deduced. The maximum value of this shortening rate compares well with the rate that may be inferred from recent trench data across the San Ramón fault and the slip associated with the past two Mw > 7 earthquakes. This suggests that the San Ramón fault is most probably the only presently active fault of the West Andean fold-and-thrust-belt and that most—if not all—the deformation is to be released seismically.
Marshall Space Flight Center Autumn 2005

NASA Technical Reports Server (NTRS)

Allen, Mike; Clar, Harry E.

2006-01-01

The East Test Area at Marshall Space Flight Center has five major test stands, each of which has two or more test positions, not counting the SSME and RD-180 engine test facilities in the West Test Area. These research and development facilities are capable of testing high pressure pumps, both fuel and oxidizer, injectors, chambers and sea-level engine assemblies, as well as simulating deep space environments in the 12, 15 and 20 foot vacuum chambers. Liquid propellant capabilities are high pressure hydrogen (liquid and gas), methane (liquid and gas), and RP-1 and high pressure LOX. Solid propellant capability includes thrust measurement and firing capability up to 1/6 scale Shuttle SRB segment. In the past six months MSFC supported multiple space access and exploration programs in the previous six months. Major programs were Space Exploration, Shuttle External Tank research, Reusable Solid Rocket Motor (RSRM) development, as well as research programs for NASA and other customers. At Test Stand 115 monopropellant ignition testing was conducted on one position. At the second position multiple ignition/variable burn time cycles were conducted on Vacuum Plasma Spatter (VPS) coated injectors. Each injector received fifty cycles; the propellants were LOX Hydrogen and the ignition source was TEA. Following completion of the monopropellant test series the stand was reconfigured to support ignition testing on a LOX Methane injector system. At TS 116 a thrust stand used to test Booster Separation Motors from the Shuttle SRB system was disassembled and moved from Chemical Systems Division s Coyote Canyon plant to MSFC. The stand was reassembled and readied for BSM testing. Also, a series of tests was run on a Pratt & Whitney Rocketdyne Low Element Density (LED) injector engine. The propellants for this engine are LOX and LH2. At TS 300 the 20 foot vacuum chamber was configured to support hydrogen testing in the Multipurpose Hydrogen Test Bed (MHTB) test article. This testing, which went 24/7 for fourteen consecutive days, demonstrated long duration storage methods intended to minimize losses of propellant in support of the Space Exploration Initiative. The facility is being converted to support similar research using liquid methane. The 12 foot chamber at TS 300 was used to create ascent profiles (both heat and altitude effects) for foam panel testing in support of the Shuttle External Tank program. At TS 500, one position was in build-up to support ATK Thiokol research into the gas dynamics associated with high pressure flow across the propellant joint in segmented solid rocket motors. The testing involves flowing high pressure gas through a 24 motor case. Initial tests will be conducted with simulated aluminum grain, followed by tests using actual propellant. The second position at TS 500 has been in build-up for testing a LOX methane thruster manufactured by KT Engineering. At the Solid Propulsion Test Area (SPTA), the first dual segment 24 solid rocket motor was fired for ATK Thiokol in support of the RSRM program. A new axial thrust measurement stand was designed and fabricated for this testing. Real Time Radiography (RTR) will be deployed to examine nozzle erosion on the next dual segment motor.
Commercialization of Australian advanced infrared technology

NASA Astrophysics Data System (ADS)

Redpath, John; Brown, Allen; Woods, William F.

1995-09-01

For several decades, the main thrust in infrared technology developments in Australia has been in two main sensor technologies: uncooled silicon chip printed bolometric sensors pioneered by DSTO's Kevin Liddiard, and precision engineered high quality Cadmium Mercury Telluride developed at DSTO under the guidance of Dr. Richard Hartley. In late 1993 a low cost infrared imaging device was developed at DSTO as a sensor for guided missiles. The combination of these three innovations made up a unique package that enabled Australian industry to break through the barriers of commercializing infrared technology. The privately owned company, R.J. Optronics Pty Ltd undertook the process of re-engineering a selection of these DSTO developments to be applicable to a wide range of infrared products. The first project was a novel infrared imager based on a Palmer scan (translated circle) mechanism. This device applies a spinning wedge and a single detector, it uses a video processor to convert the image into a standard rectangular format. Originally developed as an imaging seeker for a stand-off weapon, it is producing such high quality images at such a low cost that it is now also being adapted for a wide variety of other military and commercial applications. A technique for electronically stabilizing it has been developed which uses the inertial signals from co-mounted sensors to compensate for platform motions. This enables it to meet the requirements of aircraft, marine vessels and masthead sight applications without the use of gimbals. After tests on a three-axis motion table, several system configurations have now been successfully operated on a number of lightweight platforms, including a Cessna 172 and the Australian made Seabird Seeker aircraft.
Single and Multi-Pulse Low-Energy Conical Theta Pinch Inductive Pulsed Plasma Thruster Performance

NASA Technical Reports Server (NTRS)

Hallock, A. K.; Martin, A. K.; Polzin, K. A.; Kimberlin, A. C.; Eskridge, R. H.

2013-01-01

Impulse bits produced by conical theta-pinch inductive pulsed plasma thrusters possessing cone angles of 20deg, 38deg, and 60deg, were quantified for 500J/pulse operation by direct measurement using a hanging-pendulum thrust stand. All three cone angles were tested in single-pulse mode, with the 38deg model producing the highest impulse bits at roughly 1 mN-s operating on both argon and xenon propellants. A capacitor charging system, assembled to support repetitively-pulsed thruster operation, permitted testing of the 38deg thruster at a repetition-rate of 5 Hz at power levels of 0.9, 1.6, and 2.5 kW. The average thrust measured during multiple-pulse operation exceeded the value obtained when the single-pulse impulse bit is multiplied by the repetition rate.
Saturn Apollo Program

NASA Image and Video Library

1965-03-01

The S-IC-T stage was hoisted into the S-IC static test stand at the Marshall Space Flight Center. The S-IC-T stage was a static test vehicle not intended for flight. It was ground tested repeatedly over a period of many months to prove the vehicle's propulsion system. The 280,000-pound stage, 138 feet long and 33 feet in diameter, housed the fuel and liquid oxygen tanks that held a total of 4,400,000 pounds of liquid oxygen and kerosene. The two tanks are cornected by a 26-foot-long intertank section. Other parts of the booster included the forward skirt and the thrust structure, on which the engines were to be mounted. Five F-1 engines, each weighing 10 tons, gave the booster a total thrust of 7,500,000 pounds, roughly equivalent to 160 million horsepower.
Saturn Apollo Program

NASA Image and Video Library

1965-03-01

The S-IC-T stage is hoisted into the S-IC static test stand at the Marshall Space Flight Center. The S-IC-T stage is a static test vehicle not intended for flight. It was ground tested repeatedly over a period of many months proving the vehicle's propulsion system. The 280,000-pound stage, 138 feet long and 33 feet in diameter, houses the fuel and liquid oxygen tanks that hold a total of 4,400,000 pounds of liquid oxygen and kerosene. The two tanks are cornected by a 26-foot-long intertank section. Other parts of the booster included the forward skirt and the thrust structure, on which the engines were to be mounted. Five F-1 engines, each weighing 10 tons, gave the booster a total thrust of 7,500,000 pounds, roughly equivalent to 160 million horsepower.
Saturn Apollo Program

NASA Image and Video Library

1965-03-01

The S-IC-T stage was hoisted into the S-IC Static Test Stand at the Marshall Space Flight Center. The S-IC-T stage was a static test vehicle, not intended for flight. It was ground tested repeatedly over a period of many months to prove the vehicle's propulsion system. The 280,000-pound stage, 138 feet long and 33 feet in diameter, housed the fuel and liquid oxygen tanks that held a total of 4,400,000 pounds of liquid oxygen and kerosene. The two tanks were cornected by a 26-foot intertank section. Other parts of the booster included the forward skirt and the thrust structure, on which the engines were to be mounted. Five F-1 engines, each weighing 10 tons, gave the booster a total thrust of 7,500,000 pounds, roughly equivalent to 160 million horsepower.
A comparison of two non-thrust mobilization techniques applied to the C7 segment in patients with restricted and painful cervical rotation.

PubMed

Creighton, Doug; Gruca, Mark; Marsh, Douglas; Murphy, Nancy

2014-11-01

Cervical mobilization and manipulation have been shown to improve cervical range of motion and pain. Rotatory thrust manipulation applied to the lower cervical segments is associated with controversy and the potential for eliciting adverse reactions (AR). The purpose of this clinical trial was to describe two translatory non-thrust mobilization techniques and evaluate their effect on cervical pain, motion restriction, and whether any adverse effects were reported when applied to the C7 segment. This trial included 30 participants with painful and restricted cervical rotation. Participants were randomly assigned to receive one of the two mobilization techniques. Active cervical rotation and pain intensity measurements were recorded pre- and post-intervention. Within group comparisons were determined using the Wilcoxon signed-rank test and between group comparisons were analyzed using the Mann-Whitney U test. Significance was set at P = 0.05. Thirty participants were evaluated immediately after one of the two mobilization techniques was applied. There was a statistically significant difference (improvement) for active cervical rotation after application of the C7 facet distraction technique for both right (P = 0.022) and left (P = 0.022) rotation. Statistically significant improvement was also found for the C7 facet gliding technique for both right (P = 0.022) and left rotation (P = 0.020). Pain reduction was statistically significant for both right and left rotation after application of both techniques. Both mobilization techniques produced similar positive effects and one was not statistically superior to the other. A single application of both C7 mobilization techniques improved active cervical rotation, reduced perceived pain, and did not produce any AR in 30 patients with neck pain and movement limitation. These two non-thrust techniques may offer clinicians an additional safe and effective manual intervention for patients with limited and painful cervical rotation. A more robust experimental design is recommended to further examine these and similar cervical translatory mobilization techniques.
The Junction of Hellenic and Cyprus Arcs: a Detailed Study of the Morphology and Neogene Tectonic Evolution of the Anaximander Mountains

NASA Astrophysics Data System (ADS)

Cranshaw, J.; Aksu, A.; Hall, J.; Cifci, G.; Dondurur, D.; Yaltirak, C.

2009-05-01

The Anaximander Mountains are enigmatic highs located at the complex corner that links the Cyprus and Hellenic Arcs in the eastern Mediterranean. They are made up of several different highs: Anaximander (sensu stricto), Anaxagoras and Anaximenes. Previous work had shown that rock samples from the Anaximander Mountain have affinity with rocks exposed on land nearby in southern Turkey. This had been explained by rifting of the Mountain away from Turkey. In contrast to that, our interpretation of around 1750 km of high-resolution multi-channel seismic reflection data acquired in 2001 showed that Anaximander Mountain is part of a broadly south-verging Miocene thrust system associated with relative southward motion of the Tauride Mountains in southern Turkey. Post-Miocene motion also involves thrusting but is accompanied by transpression and rotation. The 3-dimensional nature of the geology makes mapping of the linkage of structures difficult, so we collected an additional 500 km of multi-channel seismic reflection data acquired in 2007, extending our 2001 survey further southwards into the Mediterranean Ridge. These new profiles are shot in a grid oblique to that obtained in 2001, such that the new profile intersections provide a basis for better correlation of the earlier data. We are testing our earlier interpretation through processing and interpretation of these new profiles. Here, we present examples of the new profiles and give first indications of how our earlier interpretation is broadly corroborated by the new data, but with minor adjustments. Anaximenes Mountain is imaged to the south of our previously- mapped area and is characterized as a large south-verging thrust lifting pre-Messinian strata by up to 2 km in a 12-km wide pop-up structure. Internally, Anaximenes is dissected by several splays from the bounding thrusts.
The junction of Hellenic and Cyprus arcs: a detailed study of the morphology and Neogene tectonic evolution of the Anaximander Mountains

NASA Astrophysics Data System (ADS)

Cranshaw, J.; Aksu, A.; Hall, J.; Çifçi, G.; Dondurur, D.; Yaltırak, C.

2009-04-01

The Anaximander Mountains are enigmatic highs located at the complex corner that links the Cyprus and Hellenic Arcs in the eastern Mediterranean. They are made up of several different highs: Anaximander (sensu stricto), Anaxagoras and Anaximenes. Previous work had shown that rock samples from the Anaximander Mountain have affinity with rocks exposed on land nearby in southern Turkey. This had been explained by rifting of the Mountain away from Turkey. In contrast to that, our interpretation of around 1750 km of high-resolution multi-channel seismic reflection data acquired in 2001 showed that Anaximander Mountain is part of a broadly south-verging Miocene thrust system associated with relative southward motion of the Tauride Mountains in southern Turkey. Post-Miocene motion also involves thrusting but is accompanied by transpression and rotation. The 3-dimensional nature of the geology makes mapping of the linkage of structures difficult, so we collected an additional 500 km of multi-channel seismic reflection data acquired in 2007, extending our 2001 survey further southwards into the Mediterranean Ridge. These new profiles are shot in a grid oblique to that obtained in 2001, such that the new profile intersections provide a basis for better correlation of the earlier data. We are testing our earlier interpretation through processing and interpretation of these new profiles. Here, we present examples of the new profiles and give first indications of how our earlier interpretation is broadly corroborated by the new data, but with minor adjustments. Anaximenes Mountain is imaged to the south of our previously-mapped area and is characterized as a large south-verging thrust lifting pre-Messinian strata by up to 2 km in a 12-km wide pop-up structure. Internally, Anaximenes is dissected by several splays from the bounding thrusts.
Seismicity of the Earth 1900–2010 Himalaya and vicinity

USGS Publications Warehouse

Turner, Bethan; Jenkins, Jennifer; Turner, Rebecca; Parker, Amy; Sinclair, Alison; Davies, Sian; Hayes, Gavin P.; Villaseñor, Antonio; Dart, Rirchard L.; Tarr, Arthur C.; Furlong, Kevin P.; Benz, Harley M.

2013-01-01

Seismicity in the Himalaya region predominantly results from the collision of the India and Eurasia continental plates, which are converging at a relative rate of 40–50 mm/yr. Northward underthrusting of India beneath Eurasia generates numerous earthquakes and consequently makes this area one of the most seismically hazardous regions on Earth. The surface expression of the plate boundary is marked by the foothills of the north-south trending Sulaiman Range in the west, the Indo-Burmese Arc in the east, and the east-west trending Himalaya Front in the north of India. Along the western margin of the India plate, relative motions between India and Eurasia are accommodated by strike-slip, reverse, and oblique-slip faulting resulting in the complex Sulaiman Range fold and thrust belt, and the major translational Chaman Fault in Afghanistan. Beneath the Pamir‒Hindu Kush Mountains of northern Afghanistan, earthquakes occur to depths as great as 200 km as a result of remnant lithospheric subduction. Further north again, the Tian Shan is a seismically active intra-continental mountain belt defined by a series of east-west trending thrust faults thought to be related to the broad footprint of the India-Eurasia collision. Tectonics in northern India are dominated by motion along the Main Frontal Thrust and associated thrust faults of the India-Eurasia plate boundary, which have resulted in a series of large and devastating earthquakes in (and prior to) the 20th century. The Tibetan Plateau to the north of the main plate boundary is a broad region of uplift associated with the India-Eurasia collision, and is cut by a series of generally east-west trending strike-slip faults. These include the Kunlun, Haiyuan, and the Altyn Tagh faults, all of which are left-lateral structures, and the Kara-Koram right-lateral fault. Throughout the plateau, thrust faults accommodate the north-south compressional component of crustal shortening associated with the ongoing collision of India and Eurasia, while strike-slip and normal faults accommodate east-west extension. To the east, The Longmen Shan thrust belt marks the eastern margin of the Tibetan Plateau separating the complex tectonics of the plateau region from the relatively undeformed Sichuan Basin. Further south, the left-lateral Xiangshuihe-Xiaojiiang, right-lateral Red River and right-lateral Sagaing strike-slip fault systems accommodate deformation along the eastern margin of the India plate. Deep earthquakes have also occurred in the Indo-Burmese Arc region, thought to be an expression of eastward-directed subduction of the India plate, though whether subduction is ongoing is still debated.

Destination: Space

NASA Image and Video Library

2016-05-20

RS-25 rocket engine No. 2059 is removed from the A-1 Test Stand at Stennis Space Center on May 19, 2016. The engine was tested March 10 on the stand and is ready for use on NASA’s new Space Launch System (SLS) vehicle. NASA is developing the SLS to carry humans deeper into space than ever before. The SLS core stage will be powered by four RS-25 engines. Engine No. 2059 is scheduled for use on the first crewed SLS mission, Exploration Mission-2, which will carry American astronauts beyond low-Earth orbit for the first time since 1972. The photo above shows the engine, as well as the yellow thrust frame adapter above it, which holds the engine in place for testing.
Saturn Apollo Program

NASA Image and Video Library

1967-10-01

S-IB-211, the flight version of the Saturn IB launch vehicle's first (S-IVB) stage, arrives at Marshall Space Flight Center's (MSFC's) S-IB static test stand. Between December 1967 and April 1968, the stage would undergo seven static test firings. The S-IB, developed by the MSFC and built by the Chrysler Corporation at the Michoud Assembly Facility near New Orleans, Louisiana, utilized eight H-1 engines and each produced 200,000 pounds of thrust.
Saturn Apollo Program

NASA Image and Video Library

1965-03-15

Workers at the Marshall Space Flight Center (MSFC) hoist S-IB-1, the first flight version of the Saturn IB launch vehicle's first stage (S-IB stage), into the Saturn IB static test stand on March 15, 1965. Developed by the MSFC and built by the Chrysler Corporation at the Michoud Assembly Facility (MAF) in New Orleans, Louisiana, the 90,000-pound booster utilized eight H-1 engines to produce a combined thrust of 1,600,000 pounds.
Saturn Apollo Program

NASA Image and Video Library

1967-10-01

S-IB-211, the flight version of the Saturn IB launch vehicle's (S-IVB) first stage, after installation at the Marshall Space Flight Center's (MSFC's) S-IB static test stand. Between December 1967 and April 1968, the stage would undergo seven static test firings. The S-IB, developed by the MSFC and built by the Chrysler Corporation at the Michoud Assembly Facility near New Orleans, Louisiana, utilized eight H-1 engines and each produced 200,000 pounds of thrust.
Paddling Mode of Forward Flight in Insects

NASA Astrophysics Data System (ADS)

Ristroph, Leif; Bergou, Attila J.; Guckenheimer, John; Wang, Z. Jane; Cohen, Itai

2011-04-01

By analyzing high-speed video of the fruit fly, we discover a swimminglike mode of forward flight characterized by paddling wing motions. We develop a new aerodynamic analysis procedure to show that these insects generate drag-based thrust by slicing their wings forward at low angle of attack and pushing backwards at a higher angle. Reduced-order models and simulations reveal that the law for flight speed is determined by these wing motions but is insensitive to material properties of the fluid. Thus, paddling is as effective in air as in water and represents a common strategy for propulsion through aquatic and aerial environments.
Ball motion and sliding friction in an arched outer race ball bearing

NASA Technical Reports Server (NTRS)

Hamrock, B. J.

1973-01-01

The motion of the ball and sliding friction in an arched outer race ball bearing under thrust loads is determined. Fatigue life evaluations were made. The analysis is applied to a 150 millimeter bore ball bearing. The results indicated that for high speed-light load applications the arched bearing has significant improvement in fatigue life over that of a conventional bearing. An arching of 0.254 mm (0.01 in.) was found to be an optimal. For an arched bearing it was also found that a considerable amount of spinning occurs at the outer race contacts.
Signs of essential blepharospasm: a motion-picture analysis.

PubMed

Coles, W H

1977-06-01

Motion pictures of 15 patients with essential blepharospasm were studied. Previously unrecognized signs indicated multiple cranial nerve involvement. These signs include impersistence of gaze, lid retraction, tongue thrust, head tilts, head jerks, vertical gaze spasms, and asymmetry. The sugns were also observed in a patient with bilateral blepharospasm who had a history of Bell's palsy suggesting facial nerve injury as a possible factor in blepharospasm. The presence of these signs can be explained by known neural pathways, but the site, or sites, of the lesion remains obscure. These signs may be important in assessing severity and in treatment evaluation.
Ball motion and sliding friction in an arched outer race ball bearing

NASA Technical Reports Server (NTRS)

Hamrock, B. J.

1974-01-01

The motion of the ball and sliding friction in an arched outer-race ball bearing under thrust load is determined. Fatigue life evaluations were made. The analysis is applied to a 150 millimeter bore ball bearing. The results indicated that for high speed-light load applications the arched bearing has significant improvement in fatigue life over that of a conventional bearing. An arching of 0.254 mm (0.01 in.) was found to be an optimal. For an arched bearing it was also found that a considerable amount of spinning occurs at the outer race contacts.
Present-day crustal motion along the Longitudinal Valley Fault, eastern Taiwan

NASA Astrophysics Data System (ADS)

Yu, Shui-Beih; Kuo, Long-Chen

2001-04-01

The NNE-striking Longitudinal Valley Fault (LVF) in eastern Taiwan is an extremely active high-angle thrust fault. It bounds the Coastal Range and the Longitudinal Valley, which is considered a collision boundary between the Philippine Sea and the Eurasian plates. Repeated GPS data in the Longitudinal Valley area from 1992 to 1999 are utilized to study the spatial variation of crustal motion along the LVF. With respect to Penghu in the Chinese continental margin, velocities for stations on the western side of the LVF (Longitudinal Valley and eastern Central Range) are 18-35 mm/yr in directions 283-311°, whereas those on the eastern side of the LVF, the Coastal Range, are 28-68 mm/yr in directions 303-324°. A major discontinuity of about 30 mm/yr on the rate of crustal motion across the Longitudinal Valley is attributed to the aseismic slip along the LVF as revealed by trilateration data previously. To the south of Fengping, the block motions of the Coastal Range are 31-40 mm/yr in 317-330° relative to the Central Range, while the near-fault motions are 13-33 mm/yr in 309-336°. Various partitions on the left-lateral strike-slip and convergent components along the LVF are found. In the southern Longitudinal Valley crustal motion is mainly accommodated on the LVF and the Luyeh Fault. In contrast, those in the central and northern Longitudinal Valley are partly taken up on the faults to the east of the LVF or result in the elastic deformation of the Coastal Range. The crustal motion in the northern Longitudinal Valley area is likely to be distributed in the several NE-striking thrusts in a horsetail pattern and obliquely cut the northern Coastal Range, with a small portion of fault-slips along the LVF. Data from dense-deployed GPS networks across the LVF can be employed to give better estimates of near-fault motions and delineate the surface traces of the LVF. Repeated GPS and leveling data from two stations on both ends of the Yuli Bridge that are 575 m apart clearly indicate that the surface trace of the LVF passes beneath the bridge with oblique horizontal motion of 23 mm/yr in 306° and uplift rate of 24 mm/yr.
Deformation Styles Along the Southern Alaska Margin Constrained by GPS

NASA Astrophysics Data System (ADS)

Elliott, J.; Freymueller, J. T.; Larsen, C. F.

2009-12-01

The present-day deformation observed in southcentral and southeast Alaska and the adjacent region of Canada is controlled by two main factors: ~ 50 mm/yr relative motion between the Pacific plate and North America and the Yakutat block’s collision with and accretion to southern Alaska. Over 45 mm/yr of NW-SE directed convergence from the collision is currently accommodated within the St. Elias orogen. The Fairweather, St. Elias, and Chugach ranges show the spectacular consequences of the relative tectonic motions, but the details of the plate interactions have not been well understood. Here we present GPS data from a network of over 170 campaign sites across the region. We use the data to constrain block models and forward models that characterize the nature and extent of the tectonic deformation along the Pacific-Yakutat-North America boundary. Tectonics in southeast Alaska can be described by block motion, with the Pacific plate bounding the region to the west. The fastest block motions occur along the coastal regions. The Yakutat block has a velocity of 51 ± 2.7 mm/yr towards N22 ± 2.5 deg W relative to North America. This velocity has a magnitude almost identical to that of the Pacific plate, but the azimuth is more westerly. The northeastern edge of the Yaktuat block is deforming, represented in our model by two small blocks outboard of the Fairweather fault. East of that fault, the Fairweather block rotates clockwise relative to North America, resulting in transpression along the Duke River and Eastern Denali faults. There is a clear transfer of strain from the coastal region hundreds of kilometers eastward into the Northern Cordillera block, confirming earlier suggestions that the effects of the Yakutat collision are far-reaching along its eastern margin. In contrast, deformation along the leading edge of the Yakutat collision is relatively narrowly focused within the southern half of the St. Elias orogen. The current deformation front of the Yakutat block with southern Alaska is in the vicinity of Icy Bay, where strain rates approach -1 microstrain/yr. The Malaspina thrust likely forms the northern boundary of the Yakutat block. Between Icy Bay and the Mt. St. Elias area, the tectonics cannot easily be described by block motion. The GPS data require the relative convergence to be partitioned onto multiple N-NW dipping thrust faults, resulting in a 50-70-km wide zone of deformation. This zone continues around the western side of Icy Bay into the Yakataga fold and thrust belt. North of the Mt. St. Elias area and the Bagley ice valley, roughly 100 km from the deformation front, GPS velocities are consistent with predictions of the motion of the southern Alaska block.
Comparison of Biodynamic Responses in Standing and Seated Human Bodies

NASA Astrophysics Data System (ADS)

MATSUMOTO, Y.; GRIFFIN, M. J.

2000-12-01

The dynamic responses of the human body in a standing position and in a sitting position have been compared. The apparent mass and transmissibilities to the head, six locations along the spine, and the pelvis were measured with eight male subjects exposed to vertical whole-body vibration. In both postures, the principal resonance in the apparent mass occurred in the range 5-6 Hz, with slightly higher frequencies and lower apparent mass in the standing posture. There was greater transmission of vertical vibration to the pelvis and the lower spine and greater relative motion within the lower spine in the standing posture than in the sitting posture at the principal resonance and at higher frequencies. Transmissibilities from the supporting surface (floor or seat) to the thoracic region had similar magnitudes for both standing and sitting subjects. The lumbar spine has less lordosis and may be more compressed and less flexible in the sitting posture than in the standing posture. This may have reduced the relative motions between lumbar vertebrae and both the supporting vibrating surface and the other vertebrae in the sitting posture. The characteristics of the vibration transmitted to the pelvis may have differed in the two postures due to different transmission paths. Increased forward rotation of the pelvis in the standing posture may have caused the differences in responses of the pelvis and the lower spine that were observed between the two postures.
Biomechanical evaluation of two types of short-stemmed hip prostheses compared to the trust plate prosthesis by three-dimensional measurement of micromotions.

PubMed

Fottner, Andreas; Schmid, Markus; Birkenmaier, Christof; Mazoochian, Farhad; Plitz, Wolfgang; Volkmar, Jansson

2009-06-01

Stemless and short-stemmed hip prostheses have been developed to preserve femoral bone stock. While all these prostheses claim a more or less physiological load transfer, clinical long-term results are only available for the stemless thrust plate prosthesis. In this study, the in vitro primary stability of the thrust plate prosthesis was compared to two types of short-stemmed prostheses. In addition to the well-established Mayo prosthesis, the modular Metha prosthesis was tested using cone adapters with 130 degrees and 140 degrees neck-shaft-angles. The prostheses were implanted in composite femurs and loaded dynamically (300-1700 N). Three-dimensional micromotions at the bone-prosthesis interface were measured. In addition, the three-dimensional deformations at the surface of the composite femur were measured to gain data on the strain distribution. For all tested prostheses, the micromotions did not exceed 150 microm, the critical value for osteointegration. The thrust plate prosthesis revealed similar motions as the short-stemmed prostheses. The short-stemmed prosthesis with the 130 degrees cone tended to have the highest micromotions of all tested short-stemmed prostheses. The thrust plate prosthesis revealed the lowest alteration of bone surface deformation after implantation. The comparably low micromotions of the thrust plate prosthesis and the short-stemmed prostheses should be conducive to osseous integration. The higher alteration of load transmission after implantation reveals a higher risk of stress shielding for the short-stemmed prostheses.
Device for installing rocket engines

NASA Technical Reports Server (NTRS)

George, T. R., Jr. (Inventor)

1976-01-01

A device for installing rocket engines is reported that is supported at a cant relative to vertical by an axially extensible, tiltable pedestal. A lifting platform supports the rocket engine at its thrust chamber exit, including a mount having a concentric base characterized by a concave bearing surface, a plurality of uniformly spaced legs extended radially from the base, and an annular receiver coaxially aligned with the base and affixed to the distal ends of said legs for receiving the thrust chamber exit. The lifting platform rests on a seat concentrically related to the pedestal and affixed to an extended end portion thereof having a convex bearing surface mated in sliding engagement with the concave bearing surface of the annular base for accommodating a rocking motion of the platform.
Pursuit/evasion in orbit

NASA Technical Reports Server (NTRS)

Kelley, H. J.; Cliff, E. M.; Lutze, F. H.

1981-01-01

Maneuvers available to a spacecraft having sufficient propellant to escape an antisatellite satellite (ASAT) attack are examined. The ASAT and the evading spacecraft are regarded as being in circular orbits, and equations of motion are developed for the ASAT to commence a two-impulse maneuver sequence. The ASAT employs thrust impulses which yield a minimum-time-to-rendezvous, considering available fuel. Optimal evasion is shown to involve only in-plane maneuvers, and begins as soon as the ASAT launch information is gathered and thrust activation can be initiated. A closest approach, along with a maximum evasion by the target spacecraft, is calculated to be 14,400 ft. Further research to account for ASATs in parking orbit and for generalization of a continuous control-modeled differential game is indicated.
Modeling of Nonlinear Dynamics of a Powered Paraglider

NASA Astrophysics Data System (ADS)

Watanabe, Masahito; Ochi, Yoshimasa

This paper presents a nonlinear dynamic model of a powered paraglider (PPG). The PPG is composed of a canopy and a payload with a propelling unit. The canopy is connected with the payload at two points. The model has been derived as a state vector equation under the assumption that the canopy has six degrees of freedom (DOF) and the payload has two DOF of pitching and yawing motions relative to the canopy. Friction at the connecting points between the canopy and the payload is taken into account. Time responses of the PPG without thrust have been computed using the model and the results are compared with flight experiment data. Simulation of a level flight with thrust has also been conducted.
Orbit period modulation for relative motion using continuous low thrust in the two-body and restricted three-body problems

NASA Astrophysics Data System (ADS)

Arnot, C. S.; McInnes, C. R.; McKay, R. J.; Macdonald, M.; Biggs, J.

2018-02-01

This paper presents rich new families of relative orbits for spacecraft formation flight generated through the application of continuous thrust with only minimal intervention into the dynamics of the problem. Such simplicity facilitates implementation for small, low-cost spacecraft with only position state feedback, and yet permits interesting and novel relative orbits in both two- and three-body systems with potential future applications in space-based interferometry, hyperspectral sensing, and on-orbit inspection. Position feedback is used to modify the natural frequencies of the linearised relative dynamics through direct manipulation of the system eigenvalues, producing new families of stable relative orbits. Specifically, in the Hill-Clohessy-Wiltshire frame, simple adaptations of the linearised dynamics are used to produce a circular relative orbit, frequency-modulated out-of-plane motion, and a novel doubly periodic cylindrical relative trajectory for the purposes of on-orbit inspection. Within the circular restricted three-body problem, a similar minimal approach with position feedback is used to generate new families of stable, frequency-modulated relative orbits in the vicinity of a Lagrange point, culminating in the derivation of the gain requirements for synchronisation of the in-plane and out-of-plane frequencies to yield a singly periodic tilted elliptical relative orbit with potential use as a Lunar far-side communications relay. The Δ v requirements for the cylindrical relative orbit and singly periodic Lagrange point orbit are analysed, and it is shown that these requirements are modest and feasible for existing low-thrust propulsion technology.
The 1987 Whittier Narrows, California, earthquake: A Metropolitan shock

NASA Astrophysics Data System (ADS)

Hauksson, Egill; Stein, Ross S.

1989-07-01

Just 3 hours after the Whittier Narrows earthquake struck, it became clear that a heretofore unseen geological structure was seismically active beneath metropolitan Los Angeles. Contrary to initial expectations of strike-slip or oblique-slip motion on the Whittier fault, whose north end abuts the aftershock zone, the focal mechanism of the mainshock showed pure thrust faulting on a deep gently inclined surface [Hauksson et al., 1988]. This collection of nine research reports spans the spectrum of seismological, geodetic, and geological investigations carried out as a result of the Whittier Narrows earthquake. Although unseen, the structure was not unforeseen. Namson [1987] had published a retrodeformable geologic cross section (meaning that the sedimentary strata could be restored to their original depositional position) 100 km to the west of the future earthquake epicenter in which blind, or subsurface, thrust faults were interpreted to be active beneath the folded southern Transverse Ranges. Working 25 km to the west, Hauksson [1987] had also found a surprising number of microearthquakes with thrust focal mechanisms south of the Santa Monica mountains, another clue to a subsurface system of thrust faults. Finally, Davis [1987] had presented a preliminary cross section only 18 km to the west of Whittier Narrows that identified as "fault B" the thrust that would rupture later that year. Not only was the earthquake focus and its orientation compatible with the 10-15 km depth and north dipping orientation of Davis' proposed thrust, but fault B appears to continue beneath the northern flank of the Los Angeles basin, skirting within 5 km of downtown Los Angeles, an area of dense commercial high-rise building development. These results are refined and extended by Davis et al. [this issue].
Structural record of Lower Miocene westward motion of the Alboran Domain in the Western Betics, Spain

NASA Astrophysics Data System (ADS)

Frasca, Gianluca; Gueydan, Frédéric; Brun, Jean-Pierre

2015-08-01

In the framework of the Africa-Europe convergence, the Mediterranean system presents a complex interaction between subduction rollback and upper-plate deformation during the Tertiary. The western end of the system shows a narrow arcuate geometry across the Gibraltar arc, the Betic-Rif belt, in which the relationship between slab dynamics and surface tectonics is not well understood. The present study focuses on the Western Betics, which is characterized by two major thrusts: 1) the Internal/External Zone Boundary limits the metamorphic domain (Alboran Domain) from the fold-and-thrust belts in the External Zone; 2) the Ronda Peridotites Thrust allows the juxtaposition of a strongly attenuated lithosphere section with large bodies of sub-continental mantle rocks on top of upper crustal rocks. New structural data show that two major E-W strike-slip corridors played a major role in the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60° thrusts and N140° normal faults developed simultaneously during dextral strike-slip simple shear. Olistostromic sediments of Lower Miocene age were deposited and deformed in this tectonic context and hence provide an age estimate for the inferred continuous westward translation of the Alboran Domain that is accommodated by an E-W lateral (strike-slip) ramp and a N60° frontal thrust. The crustal emplacement of large bodies of sub-continental mantle may occur at the onset of this westward thrusting in the Western Alboran domain. At lithosphere-scale, we interpret the observed deformation pattern as the subduction upper-plate expression of a lateral slab tear and its westward propagation since the Lower Miocene.
Clinical Phenotype Classifications Based on Static Varus Alignment and Varus Thrust in Japanese Patients With Medial Knee Osteoarthritis

PubMed Central

Iijima, Hirotaka; Fukutani, Naoto; Fukumoto, Takahiko; Uritani, Daisuke; Kaneda, Eishi; Ota, Kazuo; Kuroki, Hiroshi; Matsuda, Shuichi

2015-01-01

Objective To investigate the association between knee pain during gait and 4 clinical phenotypes based on static varus alignment and varus thrust in patients with medial knee osteoarthritis (OA). Methods Patients in an orthopedic clinic (n = 266) diagnosed as having knee OA (Kellgren/Lawrence [K/L] grade ≥1) were divided into 4 phenotype groups according to the presence or absence of static varus alignment and varus thrust (dynamic varus): no varus (n = 173), dynamic varus (n = 17), static varus (n = 50), and static varus + dynamic varus (n = 26). The knee range of motion, spatiotemporal gait parameters, visual analog scale scores for knee pain, and scores on the Japanese Knee Osteoarthritis Measure were used to assess clinical outcomes. Multiple logistic regression analyses identified the relationship between knee pain during gait and the 4 phenotypes, adjusted for possible risk factors, including age, sex, body mass index, K/L grade, and gait velocity. Results Multiple logistic regression analysis showed that varus thrust without varus alignment was associated with knee pain during gait (odds ratio [OR] 3.30, 95% confidence interval [95% CI] 1.08–12.4), and that varus thrust combined with varus alignment was strongly associated with knee pain during gait (OR 17.1, 95% CI 3.19–320.0). Sensitivity analyses applying alternative cutoff values for defining static varus alignment showed comparable results. Conclusion Varus thrust with or without static varus alignment was associated with the occurrence of knee pain during gait. Tailored interventions based on individual malalignment phenotypes may improve clinical outcomes in patients with knee OA. PMID:26017348
West-directed thrusting south of the eastern Himalayan syntaxis indicates clockwise crustal flow at the indenter corner during the India-Asia collision

NASA Astrophysics Data System (ADS)

Haproff, Peter J.; Zuza, Andrew V.; Yin, An

2018-01-01

Whether continental deformation is accommodated by microplate motion or continuum flow is a central issue regarding the nature of Cenozoic deformation surrounding the eastern Himalayan syntaxis. The microplate model predicts southeastward extrusion of rigid blocks along widely-spaced strike-slip faults, whereas the crustal-flow model requires clockwise crustal rotation along closely-spaced, semi-circular right-slip faults around the eastern Himalayan syntaxis. Although global positioning system (GPS) data support the crustal-flow model, the surface velocity field provides no information on the evolution of the India-Asia orogenic system at million-year scales. In this work, we present the results of systematic geologic mapping across the northernmost segment of the Indo-Burma Ranges, located directly southeast of the eastern Himalayan syntaxis. Early research inferred the area to have experienced either right-slip faulting accommodating northward indentation of India or thrusting due to the eastward continuation of the Himalayan orogen in the Cenozoic. Our mapping supports the presence of dip-slip thrust faults, rather than strike-slip faults. Specifically, the northern Indo-Burma Ranges exposes south- to west-directed ductile thrust shear zones in the hinterland and brittle fault zones in the foreland. The trends of ductile stretching lineations within thrust shear zones and thrust sheets rotate clockwise from the northeast direction in the northern part of the study area to the east direction in the southern part of the study area. This clockwise deflection pattern of lineations around the eastern Himalayan syntaxis mirrors the clockwise crustal-rotation pattern as suggested by the crustal-flow model and contemporary GPS velocity field. However, our finding is inconsistent with discrete strike-slip deformation in the area and the microplate model.

Space Shuttle Projects

NASA Image and Video Library

1977-01-01

This illustration is a cutaway of the solid rocket booster (SRB) sections with callouts. The Shuttle's two SRB's are the largest solids ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds, augmenting the Shuttle's main propulsion system during liftoff. The major design drivers for the solid rocket motors (SRM's) were high thrust and reuse. The desired thrust was achieved by using state-of-the-art solid propellant and by using a long cylindrical motor with a specific core design that allows the propellant to burn in a carefully controlled marner. At burnout, the boosters separate from the external tank and drop by parachute to the ocean for recovery and subsequent refurbishment. The boosters are designed to survive water impact at almost 60 miles per hour, maintain flotation with minimal damage, and preclude corrosion of the hardware exposed to the harsh seawater environment. Under the project management of the Marshall Space Flight Center, the SRB's are assembled and refurbished by the United Space Boosters. The SRM's are provided by the Morton Thiokol Corporation.
Experimental investigation of solid rocket motors for small sounding rockets

NASA Astrophysics Data System (ADS)

Suksila, Thada

2018-01-01

Experimentation and research of solid rocket motors are important subjects for aerospace engineering students. However, many institutes in Thailand rarely include experiments on solid rocket motors in research projects of aerospace engineering students, mainly because of the complexity of mixing the explosive propellants. This paper focuses on the design and construction of a solid rocket motor for total impulse in the class I-J that can be utilised as a small sounding rocket by researchers in the near future. Initially, the test stands intended for measuring the pressure in the combustion chamber and the thrust of the solid rocket motor were designed and constructed. The basic design of the propellant configuration was evaluated. Several formulas and ratios of solid propellants were compared for achieving the maximum thrust. The convenience of manufacturing and casting of the fabricated solid rocket motors were a critical consideration. The motor structural analysis such as the combustion chamber wall thickness was also discussed. Several types of nozzles were compared and evaluated for ensuring the maximum thrust of the solid rocket motors during the experiments. The theory of heat transfer analysis in the combustion chamber was discussed and compared with the experimental data.
Solid Propellant Microthruster Design, Fabrication, and Testing for Nanosatellites

NASA Astrophysics Data System (ADS)

Sathiyanathan, Kartheephan

This thesis describes the design, fabrication, and testing of a solid propellant microthruster (SPM), which is a two-dimensional matrix of millimeter-sized rockets each capable of delivering millinewtons of thrust and millinewton-seconds of impulse to perform fine orbit and attitude corrections. The SPM is a potential payload for nanosatellites to increase spacecraft maneuverability and is constrained by strict mass, volume, and power requirements. The dimensions of the SPM in the millimeter-scale result in a number of scaling issues that need consideration such as a low Reynolds number, high heat loss, thermal and radical quenching, and incomplete combustion. The design of the SPM, engineered to address these issues, is outlined. The SPM fabrication using low-cost commercial off-the-shelf materials and standard micromachining is presented. The selection of a suitable propellant and its customization are described. Experimental results of SPM firing to demonstrate successful ignition and sustained combustion are presented for three configurations: nozzleless, sonic nozzle, and supersonic nozzle. The SPM is tested using a ballistic pendulum thrust stand. Impulse and thrust values are calculated and presented. The performance values of the SPM are found to be consistent with existing designs.
The X3: A 200 kW Class Nested Channel Hall Thruster

NASA Astrophysics Data System (ADS)

Sheehan, J. P.

2016-10-01

Electric propulsion has seen rapid adoption in recent years for commercial, scientific, and exploratory space missions. The X3 is a three channel nested channel Hall thruster, designed to push the boundaries of high power electric propulsion for cargo transfer to Mars and large military assets. It has been operated at thermal steady state up to 30 kW of power. Thrust measurements were made on an inverted pendulum thrust stand, indicating over 2000 s specific impulse and 65 mN/kW thrust to power ratio. Detailed plume measurements were made with Faraday and Langmuir probes. The multiple concentric channels provide better performance than the sum of the individual channel operations due to superior propellant utilization from its compact design. Using a high speed camera, the breathing and spoke mode instabilities were captured in all three channels. Spoke and breathing instabilities couple between the channels, indicating that complex plasma and neutral interactions are at play. Electron transport, both cross field and in the cathode plume, are well suited to be explored in a thruster of this size. Supported under NASA contract No. NNH16CP17C.
Sprains, Strains, and Tears

MedlinePlus

... to-side • Tubing exercises in all motions (pain free) • Toe raises (advanced) • Hops – start forward and back, short hops (advanced) • Weights – Heavy tubing or cuff weights (advanced) JOINT POSITION (REGAINING BALANCE) • Standing with eyes closed – partial squats and side-to-side shifts • One-legged stand ...
Applying Low Temperature Thermochronology to Constrain Exhumation Patterns along the Eastern Denali Fault Corner, Alaska

NASA Astrophysics Data System (ADS)

Warfel, T. S.; Fitzgerald, P. G.; Benowitz, J.; Ridgway, K.; Allen, W. K.

2017-12-01

The Denali Fault (DF) constitutes a long ( 2000 km), arcuate, dextrally transpressive intracontinental fault system sketching across south-central Alaska. Strain-partitioning along the DF is accommodated as slip on the fault and fault-normal motion on a series of thrusts located north and south of the fault itself. High topography in the central and eastern Alaska Range, also locations of the greatest exhumation along the fault, are associated with restraining bends in those regions. East of the Richardson Highway, along the eastern Denali fault corner (or east-central segment of the DF), thrust faults south of the DF, including the McCallum thrust have accommodated the fault-normal component of motion along the DF. The aim of this project is to better understand what controls exhumation along large strike-slip faults, in particular the DF. Previous work along the DF in the central and eastern Alaska Range (to the west of this region) indicate the importance of fault geometry and rheological contrasts between terranes that have been juxtaposed against one another in controlling the location of exhumation. Our area of interest is a largely unstudied section along the Denali Fault (eastern DF corner) located between the DF/Hines Creek fault intersection and the Totschunda/DF intersection. We are applying a combination of apatite fission track thermochronology and apatite (U-Th)/He dating to samples collected north and south of the DF, and across thrust faults south of the DF. Thermochronology is being applied to bedrock samples, collected in vertical profiles and/or hanging wall - footwall pairs. Cobbles were also collected within a stratigraphic framework (constrained by tephras), from Miocene sediments in inverted basins south of the DF. Thermochronologic data from these cobbles; using lag-time analyses and inverse thermal models, will constrain the exhumation history of the hinterland. Assuming modern rates for slip along the DF will allow constraints to be placed on spatial and temporal patterns of exhumation and hence, help constrain the underlying control on exhumation patterns. Preliminary results indicate older AFT and AHe ages (up to 50 Ma) away from the DF but yield apatite (U-Th)/He ages as young as 2 Ma for a sample from the footwall of the closest thrust south of the DF.
Shallow seismicity of arc-continent collision near Lae, Papua New Guinea

NASA Astrophysics Data System (ADS)

Kulig, Christopher; McCaffrey, Robert; Abers, Geoffrey A.; Letz, Horst

1993-11-01

In northeastern New Guinea, the narrow Ramu-Markham Valley (RMV) separates island arc rocks to the north from those of continental origin to the south and appears to be the western, onland extension of the New Britain trench. To explore the tectonic processes at the leading edge of the island arc during collision, we operated a portable seismic network for six weeks near the city of Lae at the eastern end of the RMV. We observed a narrow, near-vertical belt of seismicity between 10 and 30 km depth, that we call the Lae Seismic Zone (LSZ), starting at the RMV in the southwest and trending northeasterly cutting across surface geologic structure. The truncation of the LSZ along a steep plane by the Ramu-Markham Fault Zone (RMFZ) and earthquake first motions suggest that the earthquakes occur in the hanging wall of a steep, N-dipping fault that crops out at the RMFZ. We also consider that the LSZ is within the lower plate of a gently dipping thrust. Below 20 km depth the microearthquake zone is truncated by a gently, NE-dipping plane coinciding in depth and dip with nodal planes of recent large ( mb = 5.6 and 6.0) thrust earthquakes. We suggest that the Huon Peninsula is being emplaced onto the Australian plate along a gently (~ 25°) dipping thrust fault that is 20 km deep beneath Lae. The RMFZ may be a steeply dipping thrust fault that connects with this gently, N-dipping thrust but accommodates little convergence at present. The LSZ trends nearly perpendicular to an anticlinal range which appears to be sheared in a left-lateral sense. P-wave first motions for earthquakes in the LSZ with steep (70° to 90° dip) nodal planes that strike parallel to the LSZ suggest a component of south-side-up displacement also. Hence, the crustal block south of the LSZ may be rising relative to the Huon Peninsula and the rapid Quaternary uplift rates estimated for the Lae coastal region may be higher than the uplift rate of the Huon Peninsula as a whole. We suggest that the LSZ reveals a tear of small offset in the Huon terrane but may be similar to a structure that produced a magnitude 7 earthquake near Madang in 1970.
Modelling the Dynamics of Bodies Self-Propelled by Exponential Mass Exhaustion

ERIC Educational Resources Information Center

Rodrigues, Hilario; Pinho, Marcos Oliveira; Portes, Dirceu, Jr.; Santiago, Arnaldo Jose

2008-01-01

We present a study of the ascending vertical motion of a self-propelled body under a uniform gravitational field suffering the action of two different types of air friction forces: linear on the velocity, which is valid for slowly moving bodies, and quadratic on the velocity. We study the special case where the thrust force is a decreasing…
An analytical model and scaling of chordwise flexible flapping wings in forward flight.

PubMed

Kodali, Deepa; Kang, Chang-Kwon

2016-12-13

Aerodynamic performance of biological flight characterized by the fluid structure interaction of a flapping wing and the surrounding fluid is affected by the wing flexibility. One of the main challenges to predict aerodynamic forces is that the wing shape and motion are a priori unknown. In this study, we derive an analytical fluid-structure interaction model for a chordwise flexible flapping two-dimensional airfoil in forward flight. A plunge motion is imposed on the rigid leading-edge (LE) of teardrop shape and the flexible tail dynamically deforms. The resulting unsteady aeroelasticity is modeled with the Euler-Bernoulli-Theodorsen equation under a small deformation assumption. The two-way coupling is realized by considering the trailing-edge deformation relative to the LE as passive pitch, affecting the unsteady aerodynamics. The resulting wing deformation and the aerodynamic performance including lift and thrust agree well with high-fidelity numerical results. Under the dynamic balance, the aeroelastic stiffness decreases, whereas the aeroelastic stiffness increases with the reduced frequency. A novel aeroelastic frequency ratio is derived, which scales with the wing deformation, lift, and thrust. Finally, the dynamic similarity between flapping in water and air is established.
On the hydrodynamics of archer fish jumping out of the water: Integrating experiments with numerical simulations

NASA Astrophysics Data System (ADS)

Sotiropoulos, Fotis; Angelidis, Dionysios; Mendelson, Leah; Techet, Alexandra

2017-11-01

Evolution has enabled fish to develop a range of thrust producing mechanisms to allow skillful movement and give them the ability to catch prey or avoid danger. Several experimental and numerical studies have been performed to investigate how complex maneuvers are executed and develop bioinspired strategies for aquatic robot design. We will discuss recent numerical advances toward the development of a computational framework for performing turbulent, two-phase flow, fluid-structure-interaction (FSI) simulations to investigate the dynamics of aquatic jumpers. We will also discuss the integration of such numerics with high-speed imaging and particle image velocimetry data to reconstruct anatomic fish models and prescribe realistic kinematics of fish motion. The capabilities of our method will be illustrated by applying it to simulate the motion of a small scale archer fish jumping out of the water to capture prey. We will discuss the rich vortex dynamics emerging during the hovering, rapid upward and gliding phases. The simulations will elucidate the thrust production mechanisms by the movement of the pectoral and anal fins and we will show that the fins significantly contribute to the rapid acceleration.
The kinematic evolution of the Serra Central Salient, Eastern Brazil: A Neoproterozoic progressive arc in northern Espinhaço fold-thrust belt

NASA Astrophysics Data System (ADS)

Bersan, Samuel Moreira; Danderfer, André; Lagoeiro, Leonardo; Costa, Alice Fernanda de Oliveira

2017-12-01

Convex-to-the-foreland map-view curves are common features in fold-thrust belts around cratonic areas. These features are easily identifiable in belts composed of supracrustal rocks but have been rarely described in rocks from relatively deeper crustal levels where plastic deformation mechanisms stand out. Several local salients have been described in Neoproterozoic marginal fold-thrust belts around the São Francisco craton. In the northern part of the Espinhaço fold-thrust belt, which borders the eastern portion of the São Francisco craton, both Archean-Paleoproterozoic basement rocks and Proterozoic cover rocks are involved in the so-called Serra Central salient. A combination of conventional structural analysis and microstructural and paleostress studies were conducted to characterize the kinematic and the overall architecture and processes involved in the generation of this salient. The results allowed us to determine that the deformation along the Serra Central salient occur under low-grade metamorphic conditions and was related to a gently oblique convergence with westward mass transport that developed in a confined flow, controlled by two transverse bounding shear zones. We propose that the Serra Central salient nucleates as a basin-controlled primary arc that evolves to a progressive arc with secondary vertical axis rotation. This secondary rotation, well-illustrated by the presence of two almost orthogonal families of folds, was dominantly controlled by buttress effect exert by a basement high located in the foreland of the Serra Central salient.
HESTIA Commodities Exchange Pallet and Sounding Rocket Test Stand

NASA Technical Reports Server (NTRS)

Chaparro, Javier

2013-01-01

During my Spring 2016 internship, my two major contributions were the design of the Commodities Exchange Pallet and the design of a test stand for a 100 pounds-thrust sounding rocket. The Commodities Exchange Pallet is a prototype developed for the Human Exploration Spacecraft Testbed for Integration and Advancement (HESTIA) program. Under the HESTIA initiative the Commodities Exchange Pallet was developed as a method for demonstrating multi-system integration thru the transportation of In-Situ Resource Utilization produced oxygen and water to a human habitat. Ultimately, this prototype's performance will allow for future evaluation of integration, which may lead to the development of a flight capable pallet for future deep-space exploration missions. For HESTIA, my main task was to design the Commodities Exchange Pallet system to be used for completing an integration demonstration. Under the guidance of my mentor, I designed, both, the structural frame and fluid delivery system for the commodities pallet. The fluid delivery system includes a liquid-oxygen to gaseous-oxygen system, a water delivery system, and a carbon-dioxide compressors system. The structural frame is designed to meet safety and transportation requirements, as well as the ability to interface with the ER division's Portable Utility Pallet. The commodities pallet structure also includes independent instrumentation oxygen/water panels for operation and system monitoring. My major accomplishments for the commodities exchange pallet were the completion of the fluid delivery systems and the structural frame designs. In addition, parts selection was completed in order to expedite construction of the prototype, scheduled to begin in May of 2016. Once the commodities pallet is assembled and tested it is expected to complete a fully integrated transfer demonstration with the ISRU unit and the Environmental Control and Life Support System test chamber in September of 2016. In addition to the development of the Commodities Exchange Pallet, I also assisted in preparation for testing the upper stage of a sounding rocket developed as a Center Innovation Fund project. The main objective of this project is to demonstrate the integration between a propulsion system and a solid oxide fuel cell (SOFC). The upper stage and SOFC are scheduled to complete an integrated test in August of 2016. As part of preparation for scheduled testing, I was responsible for designing the upper stage's test stand/support structure and main engine plume deflector to be used during hot-fire testing (fig. 3). The structural components of the test stand need to meet safety requirements for operation of the propulsion system, which consist of a 100 pounds-thrust main engine and two 15 pounds-thrust reaction control thrusters. My main accomplishment for this project was the completion of the design and the parts selection for construction of the structure, scheduled to begin late April of 2016.
Turtle mimetic soft robot with two swimming gaits.

PubMed

Song, Sung-Hyuk; Kim, Min-Soo; Rodrigue, Hugo; Lee, Jang-Yeob; Shim, Jae-Eul; Kim, Min-Cheol; Chu, Won-Shik; Ahn, Sung-Hoon

2016-05-04

This paper presents a biomimetic turtle flipper actuator consisting of a shape memory alloy composite structure for implementation in a turtle-inspired autonomous underwater vehicle. Based on the analysis of the Chelonia mydas, the flipper actuator was divided into three segments containing a scaffold structure fabricated using a 3D printer. According to the filament stacking sequence of the scaffold structure in the actuator, different actuating motions can be realized and three different types of scaffold structures were proposed to replicate the motion of the different segments of the flipper of the Chelonia mydas. This flipper actuator can mimic the continuous deformation of the forelimb of Chelonia mydas which could not be realized in previous motor based robot. This actuator can also produce two distinct motions that correspond to the two different swimming gaits of the Chelonia mydas, which are the routine and vigorous swimming gaits, by changing the applied current sequence of the SMA wires embedded in the flipper actuator. The generated thrust and the swimming efficiency in each swimming gait of the flipper actuator were measured and the results show that the vigorous gait has a higher thrust but a relatively lower swimming efficiency than the routine gait. The flipper actuator was implemented in a biomimetic turtle robot, and its average swimming speed in the routine and vigorous gaits were measured with the vigorous gait being capable of reaching a maximum speed of 11.5 mm s(-1).
Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)

USGS Publications Warehouse

Granja, Bruna J.L.; ten Brink, Uri S.; Carbó-Gorosabel, Andrés; Muñoz-Martín, A.; Gomez, Ballesteros M.

2009-01-01

Multibeam bathymetry data acquired during the 2005 Spanish R/V Hesp??rides cruise and reprocessed multichannel seismic profiles provide the basis for the analysis of the morphology and deformation in the central Muertos Trough and Muertos thrust belt. The Muertos Trough is an elongated basin developed where the Venezuelan Basin crust is thrusted under the Muertos fold-and-thrust belt. Structural variations along the Muertos Trough are suggested to be a consequence of the overburden of the asymmetrical thrust belt and by the variable nature of the Venezuelan Basin crust along the margin. The insular slope can be divided into three east-west trending slope provinces with high lateral variability which correspond to different accretion stages: 1) The lower slope is composed of an active sequence of imbricate thrust slices and closed fold axes, which form short and narrow accretionary ridges and elongated slope basins; 2) The middle slope shows a less active imbricate structure resulting in lower superficial deformation and bigger slope basins; 3) The upper slope comprises the talus region and extended terraces burying an island arc basement and an inactive imbricate structure. The talus region is characterized by a dense drainage network that transports turbidite flows from the islands and their surrounding carbonate platform areas to the slope basins and sometimes to the trough. In the survey area the accommodation of the ongoing east-west differential motion between the Hispaniola and the Puerto Rico-Virgin Islands blocks takes place by means of diffuse deformation. The asymmetrical development of the thrust belt is not related to the geological conditions in the foreland, but rather may be caused by variations in the geometry and movement of the backstop. The map-view curves of the thrust belt and the symmetry of the recesses suggest a main north-south convergence along the Muertos margin. The western end of the Investigator Fault Zone comprises a broad band of active normal faults which result in high instability of the upper insular slope. ?? 2009 Elsevier B.V.
The distribution of lumbar intervertebral angles in upright standing and extension is related to low back pain developed during standing.

PubMed

Viggiani, Daniel; Gallagher, Kaitlin M; Sehl, Michael; Callaghan, Jack P

2017-11-01

Lumbar lordosis measures are poorly related to clinical low back pain, however using a controlled exposure such as prolonged standing to identify pain groups may clarify this relationship. The purpose of this study was to determine the distribution of lumbar intervertebral angles in asymptomatic persons who do (pain developers) and do not (non-pain developers) develop low back pain during standing. Sagittal plane lumbar spine radiographs of eight pain developers and eight non-pain developers were taken in three poses: upright standing, full extension and full flexion. Measures of vertebral end plate orientations from L1 to S1 were taken in each pose to compute: intervertebral angles, contribution of each level to the total curve, total lordosis, ranges of motion, relative pose positioning within the range of motion, vertebral shape, and lumbar spine recurve. Measures were compared between pain groups and lumbar levels. Pain group differences in intervertebral angles and level contributions were greatest in the full extension pose, with pain developers having greater contributions from higher lumbar levels and fewer contributions from lower levels than non-pain developers. Pain group differences in intervertebral angle distributions were less pronounced in upright standing and non-existent in full flexion. No other measures differentiated pain groups. Although participants had similar gross-lumbar spine curvature characteristics, non-pain developers have more curvature at lower levels in upright standing and full extension. These differences in regional vertebral kinematics may partially be responsible for standing-induced low back pain. Copyright © 2017 Elsevier Ltd. All rights reserved.
Test stand performance of a convertible engine for advanced V/STOL and rotorcraft propulsion

NASA Technical Reports Server (NTRS)

Mcardle, Jack G.

1987-01-01

A variable inlet guide vane (VIGV) convertible engine that could be used to power future high-speed V/STOL and rotorcraft was tested on an outdoor stand. The engine ran stably and smoothly in the turbofan, turboshaft, and dual (combined fan and shaft) power modes. In the turbofan mode with the VIGV open, fuel consumption was comparable to that of a conventional turbofan engine. In the turboshaft mode with the VIGV closed, fuel consumption was higher than that of present turboshaft engines because power was wasted in churning fan-tip air flow. In dynamic performance tests with a specially built digital engine control and using a waterbrake dynamometer for shaft load, the engine responded effectively to large steps in thrust command and shaft torque.
Saturn Apollo Program

NASA Image and Video Library

1967-09-09

This image depicts a firing of a single H-1 engine at the Marshall Space Flight Center’s (MSFC’s) Power Plant test stand. This 1950s test stand, inherited from the Army, was used to test fire engines until the Test Area was completed in the latter 1960s. The H-1 engine was the workhorse of the first Saturn launch vehicles and used in the Saturn I, Block 1 and II, and in the Saturn IB. The eight H-1 engines were attached to a thrust frame on the vehicle’s aft end in two different ways. Four engines are rigidly attached to the inboard position and canted at a three degree angle to the long axis of the booster. The other four engines, mounted in the outboard position, are canted at six degrees.
Dr. von Braun Standing by Five F-1 Engines

NASA Technical Reports Server (NTRS)

2004-01-01

A pioneer of America's space program, Dr. von Braun stands by the five F-1 engines of the Saturn V launch vehicle. This Saturn V vehicle is an actual test vehicle which has been displayed at the U.S. Space Rocket Center in Huntsville, Alabama. Designed and developed by Rocketdyne under the direction of the Marshall Space Flight Center, a cluster of five F-1 engines was mounted on the Saturn V S-IC (first) stage. The engines measured 19-feet tall by 12.5-feet at the nozzle exit and burned 15 tons of liquid oxygen and kerosene each second to produce 7,500,000 pounds of thrust. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon.
Test stand performance of a convertible engine for advanced V/STOL and rotorcraft propulsion

NASA Technical Reports Server (NTRS)

Mcardle, Jack G.

1988-01-01

A variable inlet guide vane (VIGV) convertible engine that could be used to power future high-speed V/STOL and rotorcraft was tested on an outdoor stand. The engine ran stably and smoothly in the turbofan, turboshaft, and dual (combined fan and shaft) power modes. In the turbofan mode with the VIGV open, fuel consumption was comparable to that of a conventional turbofan engine. In the turboshaft mode with the VIGV closed, fuel consumption was higher than that of present turboshaft engines because power was wasted in churning fan-tip air flow. In dynamic performance tests with a specially built digital engine control and using a waterbrake dynamometer for shaft load, the engine responded effectively to large steps in thrust command and shaft torque.
An experimental study on the coalescence process of binary droplets in oil under ultrasonic standing waves.

PubMed

Luo, Xiaoming; Cao, Juhang; He, Limin; Wang, Hongping; Yan, Haipeng; Qin, Yahua

2017-01-01

The coalescence process of binary droplets in oil under ultrasonic standing waves was investigated with high-speed photography. Three motion models of binary droplets in coalescence process were illustrated: (1) slight translational oscillation; (2) sinusoidal translational oscillation; (3) migration along with acoustic streaming. To reveal the droplets coalescence mechanisms, the influence of main factors (such as acoustic intensity, droplet size, viscosity and interfacial tension, etc) on the motion and coalescence of binary droplets was studied under ultrasonic standing waves. Results indicate that the shortest coalescence time is achieved when binary droplets show sinusoidal translational oscillation. The corresponding acoustic intensity in this case is the optimum acoustic intensity. Under the optimum acoustic intensity, drop size decrease will bring about coalescence time decrease by enhancing the binary droplets oscillation. Moreover, there is an optimum interfacial tension to achieve the shortest coalescence time. Copyright © 2016 Elsevier B.V. All rights reserved.

Self-propelled instrumented deep drilling system

NASA Technical Reports Server (NTRS)

Myrick, Thomas M. (Inventor); Gorevan, Stephen (Inventor)

2006-01-01

An autonomous subsurface drilling device has spaced-apart forward and rearward feet sections coupled to an axial thruster mechanism between them to operate using an inchworm method of mobility. In one embodiment, forward and rearward drill sections are carried on forward and rearward feet sections for drilling into material in the borehole in both forward and rearward directions, to allow the device to maneuver in any direction underground. In another embodiment, a front drill section has a drill head for cutting into the borehole and conveying cuttings through a center spine tube to an on-board depository for the cuttings. The feet sections of the device employ a foot scroll drive unit to provide radial thrust and synchronous motion to the feet for gripping the borehole wall. The axial thrust mechanism has a tandem set of thrusters in which the second thruster is used to provide the thrust needed for drilling, but not walking. A steering mechanism composed of concentric inner and outer eccentric rings provided with the rearward feet section allow small corrections in both direction and magnitude to the drilling direction as drilling commences.
Cathodoluminescence, fluid inclusion and stable C-O isotope study of tectonic breccias from thrusting plane of a thin-skinned calcareous nappe

NASA Astrophysics Data System (ADS)

Milovský, Rastislav; van den Kerkhof, Alfons; Hoefs, Jochen; Hurai, Vratislav; Prochaska, Walter

2012-03-01

Basal hydraulic breccias of alpine thin-skinned Muráň nappe were investigated by means of cathodoluminescence petrography, stable isotope geochemistry and fluid inclusions analysis. Our study reveals an unusual dynamic fluid regime along basal thrust plane during final episode of the nappe emplacement over its metamorphic substratum. Basal thrusting fluids enriched in 18O, silica, alumina, alkalies and phosphates were generated in the underlying metamorphosed basement at epizonal conditions corresponding to the temperatures of 400-450°C. The fluids fluxed the tectonized nappe base, leached evaporite-bearing formations in hangingwall, whereby becoming oversaturated with sulphates and chlorides. The fluids further modified their composition by dedolomitization and isotopic exchange with the host carbonatic cataclasites. Newly formed mineral assemblage of quartz, phlogopite, albite, potassium feldspar, apatite, dravite tourmaline and anhydrite precipitated from these fluids on cooling down to 180-200°C. Finally, the cataclastic mush was cemented by calcite at ambient anchizonal conditions. Recurrent fluid injections as described above probably enhanced the final motion of the Muráň nappe.
Nonlinear feedback control for high alpha flight

NASA Technical Reports Server (NTRS)

Stalford, Harold

1990-01-01

Analytical aerodynamic models are derived from a high alpha 6 DOF wind tunnel model. One detail model requires some interpolation between nonlinear functions of alpha. One analytical model requires no interpolation and as such is a completely continuous model. Flight path optimization is conducted on the basic maneuvers: half-loop, 90 degree pitch-up, and level turn. The optimal control analysis uses the derived analytical model in the equations of motion and is based on both moment and force equations. The maximum principle solution for the half-loop is poststall trajectory performing the half-loop in 13.6 seconds. The agility induced by thrust vectoring capability provided a minimum effect on reducing the maneuver time. By means of thrust vectoring control the 90 degrees pitch-up maneuver can be executed in a small place over a short time interval. The agility capability of thrust vectoring is quite beneficial for pitch-up maneuvers. The level turn results are based currently on only outer layer solutions of singular perturbation. Poststall solutions provide high turn rates but generate higher losses of energy than that of classical sustained solutions.
Perturbed Equations of Motion for Formation Flight Near the Sun-Earth L2 Point

NASA Technical Reports Server (NTRS)

Luquette, Richard; Segerman, A. M.; Zedd, M. F.

2005-01-01

NASA is planning missions to the vicinity of the Sun-Earth L(sub 2) point, some involving a distributed system of telescope spacecraft, configured in a plane about a hub. Several sets of differential equations are written for the formation flight of such telescopes relative to the hub, with varying levels of fidelity. Effects are cast as additive perturbations to the circular restricted three-body problem, expanded in terms of the system distanced, to an accuracy of 10-20 m. These include Earth's orbital eccentricity, lunar motion, solar radiation pressure, and small thrusting forces. Simulations validating the expanded differential equations are presented.
Analysis of cryogenic propellant behavior in microgravity and low thrust environments

NASA Technical Reports Server (NTRS)

Fisher, Mark F.; Schmidt, George R.; Martin, James J.

1991-01-01

Predictions of a CFD program calculating a fluid-free surface shape and motion as a function of imposed acceleration are validated against the drop-tower test data collected to support design and performance assessments of the Saturn S-IVB stage liquid-hydrogen tank. The drop-tower facility, experimental package, and experiment procedures are outlined, and the program is described. It is noted that the validation analysis confirms the program's suitability for predicting low-g fluid slosh behavior, and that a similar analysis could examine the effect of incorporating baffles and screens to impede initiation of any unwanted side loads due to slosh. It is concluded that in actual vehicle applications, the engine thrust tailoff profile should be included in computer simulations if the precise interface versus time definition is needed.
Investigation of wing upper surface flow-field disturbance due to NASA DC-8-72 in-flight inboard thrust-reverser deployment

NASA Technical Reports Server (NTRS)

Hamid, Hedayat U.; Margason, Richard J.; Hardy, Gordon

1995-01-01

An investigation of the wing upper surface flow-field disturbance due to in-flight inboard thrust reverser deployment on the NASA DC-8-72, which was conducted cooperatively by NASA Ames, the Federal Aviation Administration (FAA), McDonnell Douglas, and the Aerospace Industry Association (AIA), is outlined and discussed in detail. The purpose of this flight test was to obtain tufted flow visualization data which demonstrates the effect of thrust reverser deployment on the wing upper surface flow field to determine if the disturbed flow regions could be modeled by computational methods. A total of six symmetric thrust reversals of the two inboard engines were performed to monitor tuft and flow cone patterns as well as the character of their movement at the nominal Mach numbers of 0.55, 0.70, and 0.85. The tufts and flow cones were photographed and video-taped to determine the type of flow field that occurs with and without the thrust reversers deployed. In addition, the normal NASA DC-8 onboard Data Acquisition Distribution System (DADS) was used to synchronize the cameras. Results of this flight test will be presented in two parts. First, three distinct flow patterns associated with the above Mach numbers were sketched from the motion videos and discussed in detail. Second, other relevant aircraft parameters, such as aircraft's angular orientation, altitude, Mach number, and vertical descent, are discussed. The flight test participants' comments were recorded on the videos and the interested reader is referred to the video supplement section of this report for that information.
Effect of tibial plateau leveling on stability of the canine cranial cruciate-deficient stifle joint: an in vitro study.

PubMed

Reif, Ullrich; Hulse, Donald A; Hauptman, Joe G

2002-01-01

To evaluate the effect of tibial plateau leveling on joint motion in canine stifle joints in which the cranial cruciate ligament (CCL) had been severed. In vitro cadaver study. Six canine cadaver hind legs. Radiographs of the stifle joints were made to evaluate the tibial plateau angle with respect to the long axis of the tibia. The specimens were mounted in a custom-made testing device to measure cranio-caudal translation of the tibia with respect to the femur. An axial load was applied to the tibia, and its position was recorded in the normal stifle, after transection of the CCL, and after tibial plateau leveling. Further, the amount of caudal tibial thrust was measured in the tibial plateau leveled specimen while series of eight linearly increasing axial tibial loads were applied. Transection of the CCL resulted in cranial tibial translation when axial tibial load was applied. After tibial plateau leveling, axial loading resulted in caudal translation of the tibia. Increasing axial tibial load caused a linear increase in caudal tibial thrust in all tibial plateau-leveled specimens. After tibial plateau leveling, axial tibial load generates caudal tibial thrust, which increases if additional axial load is applied. Tibial plateau leveling osteotomy may prevent cranial translation during weight bearing in dogs with CCL rupture by converting axial load into caudal tibial thrust. The amount of caudal tibial thrust seems to be proportional to the amount of weight bearing. Copyright 2002 by The American College of Veterinary Surgeons
Interseismic coupling, seismic potential, and earthquake recurrence on the southern front of the Eastern Alps (NE Italy)

NASA Astrophysics Data System (ADS)

Cheloni, D.; D'Agostino, N.; Selvaggi, G.

2014-05-01

Here we use continuous GPS observations to document the geodetic strain accumulation across the South-Eastern Alps (NE Italy). We estimate the interseismic coupling on the intracontinental collision thrust fault and discuss the seismic potential and earthquake recurrence. We invert the GPS velocities using the back slip approach to simultaneously estimate the relative angular velocity and the degree of interseismic coupling on the thrust fault that separates the Eastern Alps and the Venetian-Friulian plain. Comparison between the rigid rotation predicted motion and the shortening observed across the area indicates that the South-Eastern Alpine thrust front absorbs about 70% of the total convergence between the Adria and Eurasia plates. The coupling is computed on a north dipping fault following the continuous external seismogenic thrust front of the South-Eastern Alps. The modeled thrust fault is currently locked from the surface to a depth of ≈10 km. The transition zone between locked and creeping portions of the fault roughly corresponds with the belt of microseismicity parallel and to the north of the mountain front. The estimated moment deficit rate is 1.3 ± 0.4 × 1017 Nm/yr. The comparison between the estimated moment deficit and that released historically by the earthquakes suggests that to account for the moment deficit the following two factors or their combination should be considered: (1) a significant part of the observed interseismic coupling is released aseismically and (2) infrequent "large" events with long return period (> 1000 years) and with magnitudes larger than the value assigned to the largest historical events (Mw≈ 6.7).
Kinematics and hydrodynamics analysis of swimming anurans reveals striking inter-specific differences in the mechanism for producing thrust.

PubMed

Richards, Christopher T

2010-02-15

This study aimed to compare the swimming kinematics and hydrodynamics within and among aquatic and semi-aquatic/terrestrial frogs. High-speed video was used to obtain kinematics of the leg joints and feet as animals swam freely across their natural range of speeds. Blade element analysis was then used to model the hydrodynamic thrust as a function of foot kinematics. Two purely aquatic frogs, Xenopus laevis and Hymenochirus boettgeri, were compared with two semi-aquatic/terrestrial frogs, Rana pipiens and Bufo americanus. The four species performed similarly. Among swimming strokes, peak stroke velocity ranged from 3.3+/-1.1 to 20.9+/-2.5, from 6.8+/-2.1 to 28.6+/-3.7 and from 4.9+/-0.5 to 20.9+/-4.1 body lengths per second (BL s(-1)) in X. laevis, H. boettgeri and R. pipiens, respectively (means +/- s.d.; N=4 frogs for each). B. americanus swam much more slowly at 3.1+/-0.3 to 7.0+/-2.0 BL s(-1) (N=3 frogs). Time-varying joint kinematics patterns were superficially similar among species. Because foot kinematics result from the cumulative motion of joints proximal to the feet, small differences in time-varying joint kinematics among species resulted in species-specific foot kinematics (therefore hydrodynamics) patterns. To obtain a simple measure of the hydrodynamically useful motion of the foot, this study uses 'effective foot velocity' (EFV): a measure of the component of foot velocity along the axis of swimming. Resolving EFV into translational and rotational components allows predictions of species-specific propulsion strategies. Additionally, a novel kinematic analysis is presented here that enables the partitioning of translational and rotational foot velocity into velocity components contributed by extension at each individual limb joint. Data from the kinematics analysis show that R. pipiens and B. americanus translated their feet faster than their body moved forward, resulting in positive net translational EFV. Conversely, translational EFV was slower than the body velocity in H. boettgeri and X. laevis, resulting in negative net translational EFV. Consequently, the translational component of thrust (caused mostly by hip, knee and ankle extension) was twofold higher than rotational thrust in Rana pipiens. Likewise, rotational components of thrust were nearly twofold higher than translational components in H. boettgeri. X. laevis, however, was the most skewed species observed, generating nearly 100% of total thrust by foot rotation generated by hip, ankle and tmt extension. Thus, this study presents a simple kinematics analysis that is predictive of hydrodynamic differences among species. Such differences in kinematics reveal a continuum of different propulsive strategies ranging from mostly rotation-powered (X. laevis) to mostly translation-powered (R. pipiens) swimming.
Comparison of Electrostatic Fins with Piezoelectric Impact Hammer Techniques to Extend Impulse Calibration Range of a Torsional Thrust Stand (Preprint)

DTIC Science & Technology

2011-03-23

prac- tical max impulse to 1mNs. The newly developed Piezo - electric Impact Hammer (PIH) calibration system over- comes geometric limits of ESC...the fins to behave as part of an LRC circuit which results in voltage oscillations. By adding a resistor in series between the pulse generator and...series resistor as well as the effects of no loading on the pulse generator. III. PIEZOELECTRIC IMPACT HAMMER SYSTEM The second calibration method tested
Saturn Apollo Program

NASA Image and Video Library

1965-08-01

Two workers are dwarfed by the five J-2 engines of the Saturn V second stage (S-II) as they make final inspections prior to a static test firing by North American Space Division. These five hydrogen -fueled engines produced one million pounds of thrust, and placed the Apollo spacecraft into earth orbit before departing for the moon. The towering 363-foot Saturn V was a multi-stage, multi-engine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.
Amelioration of Acute Sequelae of Blast Induced Mild Traumatic Brain Injury by N-Acetyl Cysteine: A Double-Blind, Placebo Controlled Study

DTIC Science & Technology

2013-01-23

turning of the subjects head by the investigator [17]), an abnormal Romberg /tandem Rom- berg test (excessive swaying or falling while attempting to stand...of ,22. Criteria for resolution of balance dysfunction were no subjective dizziness, normal head thrust and Romberg tests , and a normal DGI...Agrawal Y, Carey JP, Hoffman HJ, Sklare DA, Schubert MC (2011) The modified Romberg Balance Test : normative data in U.S. adults. Otol Neurotol 32: 309–311
Estimation of ICBM (Intercontinental Ballistic Missile) Performance Parameters

DTIC Science & Technology

1985-12-01

Formulation . . . . . 42 Staging Event Detection . . . . . . 43 Staging Estimator for Two State System . 46 * Staging Time and Vehicle Parameter...6 4. Land Based Sensor Coordinate System . . . . 10 5. Radar Site Geometry . . . . . . . . . 1 6. Observation Geometry . . . . . . . . . 12 7...Ve dm mi + dmi+d Figure 3. Rocket Thrust of fuel, the equation of motion of the rocket can be devel--S oped. This is a closed system of particles
Optimum acoustic design of free-running low speed propellers

NASA Technical Reports Server (NTRS)

Ormsbee, A. I.; Woan, C. J.

1977-01-01

A theoretical analysis is conducted concerning the effect of blade loading on the noise output of a free-running propeller in axial motion. The minimization of the mean square sound pressure at a point in space is considered, taking into account constraints on propeller thrust and torque. Attention is given to aerodynamic equations, acoustic equations, the expansion of the aerodynamic variables, and the nonlinear programming formulation.
Crustal deformation rates in Assam Valley, Shillong Plateau, Eastern Himalaya, and Indo-Burmese region from 11 years (2002-2013) of GPS measurements

NASA Astrophysics Data System (ADS)

Barman, Prakash; Jade, Sridevi; Shrungeshwara, T. S.; Kumar, Ashok; Bhattacharyya, Sanjeev; Ray, Jagat Dwipendra; Jagannathan, Saigeetha; Jamir, Wangshi Menla

2017-09-01

The present study reports the contemporary deformation of the tectonically complex northeast India using 11 years (2002-2013) of GPS observations. The central Shillong Plateau and few sites north of Plateau located in Assam Valley behave like a rigid block with 7 mm/year India-fixed southward velocity. The Euler pole of rotation of this central Shillong Plateau-Assam Valley (SH-AS) block is estimated to be at -25.1° ± 0.2°N, -97.8° ± 1.8°E with an angular velocity of 0.533° ± 0.10° Myr-1 relative to India-fixed reference frame. Kopili fault located between Shillong Plateau and Mikir massif records a dextral slip of 4.7 ± 1.3 mm/year with a locking depth of 10.2 ± 1.4 km indicating the fragmentation of Assam Valley across the fault. Presently, western edge of Mikir massif appears to be locked to Assam block indicating strain accumulation in this region. First-order elastic dislocation modelling of the GPS velocities estimates a slip rate of 16 mm/year along the Main Himalayan Thrust in Eastern Himalaya which is locked over a width of 130 km from the surface to a depth of 17 km with underthrusting Indian plate. Around 9 mm/year arc-normal convergence is accommodated in Lesser Himalaya just south of Main Central Thrust indicating high strain accumulation. Out of 36 mm/year (SSE) India-Sunda plate motion, about 16 mm/year motion is accommodated in Indo-Burmese Fold and Thrust Belt, both as normal convergence ( 6 mm/year) and active slip ( 7-11 mm/year) in this region.
Persistent Seismicity and Energetics of the 2010 Earthquake Sequence of the Gros Ventre-Teton Area, Wyoming

NASA Astrophysics Data System (ADS)

Farrell, J.

2010-12-01

Farrell, Jamie M. Smith, Robert Massin, Fred White, Bonnie Department of Geology and Geophysics University of Utah Salt Lake City, Utah 84112 Seismicity has persisted along a zone south of the Yellowstone volcanic field in the Gros Ventre Range, Wyoming, and on the eastern edge of the asesimic Quat. high slip-rate Teton fault. Concentrated seismicity has in this area occurs in sporadic sequences documented since 1923 with notable earthquakes in the decade preceding the deadly 1925 Gros Ventre slide that eventually lead to the failure of a dam blocked by the slide in 1927. Notable seismicity of the Gros Ventre region, using data from the Teton, Yellowstone and USArray seismic networks, has continued in the last decade with sequences in 2002, 2004, culminating in an energetic sequence beginning in May, 2009 through a sequence of more than 180 well located earthquakes mainly from August 5 to August 17 of 0.5
Buoyant subduction on Venus: Implications for subduction around coronae

NASA Astrophysics Data System (ADS)

Burt, J. D.; Head, J. W.

1993-03-01

Potentially low lithospheric densities, caused by high Venus surface and perhaps mantle temperatures, could inhibit the development of negative buoyancy-driven subduction and a global system of plate tectonics/crustal recycling on that planet. No evidence for a global plate tectonic system was found so far, however, specific features strongly resembling terrestrial subduction zones in planform and topographic cross-section were described, including trenches around large coronae and chasmata in eastern Aphrodite Terra. The cause for the absence, or an altered expression, of plate tectonics on Venus remains to be found. Slab buoyancy may play a role in this difference, with higher lithospheric temperatures and a tendency toward positive buoyancy acting to oppose the descent of slabs and favoring under thrusting instead. The effect of slab buoyancy on subduction was explored and the conditions which would lead to under thrusting versus those allowing the formation of trenches and self-perpetuating subduction were defined. Applying a finite element code to assess the effects of buoyant forces on slabs subducting into a viscous mantle, it was found that mantle flow induced by horizontal motion of the convergent lithosphere greatly influences subduction angle, while buoyancy forces produce a lesser effect. Induced mantle flow tends to decrease subduction angle to near an under thrusting position when the subducting lithosphere converges on a stationary overriding lithosphere. When the overriding lithosphere is in motion, as in the case of an expanding corona, subduction angles are expected to increase. An initial stage involved estimating the changes in slab buoyancy due to slab healing and pressurization over the course of subduction. Modeling a slab, descending at a fixed angle and heated by conduction, radioactivity, and the heat released in phase changes, slab material density changes due to changing temperature, phase, and pressure were derived.
Effect of outer wing separation on lift and thrust generation in a flapping wing system.

PubMed

Mahardika, Nanang; Viet, Nguyen Quoc; Park, Hoon Cheol

2011-09-01

We explore the implementation of wing feather separation and lead-lagging motion to a flapping wing. A biomimetic flapping wing system with separated outer wings is designed and demonstrated. The artificial wing feather separation is implemented in the biomimetic wing by dividing the wing into inner and outer wings. The features of flapping, lead-lagging, and outer wing separation of the flapping wing system are captured by a high-speed camera for evaluation. The performance of the flapping wing system with separated outer wings is compared to that of a flapping wing system with closed outer wings in terms of forward force and downward force production. For a low flapping frequency ranging from 2.47 to 3.90 Hz, the proposed biomimetic flapping wing system shows a higher thrust and lift generation capability as demonstrated by a series of experiments. For 1.6 V application (lower frequency operation), the flapping wing system with separated wings could generate about 56% higher forward force and about 61% less downward force compared to that with closed wings, which is enough to demonstrate larger thrust and lift production capability of the separated outer wings. The experiments show that the outer parts of the separated wings are able to deform, resulting in a smaller amount of drag production during the upstroke, while still producing relatively greater lift and thrust during the downstroke.
The role of tip deflection on the thrust produced by rigid flapping fins

NASA Astrophysics Data System (ADS)

Huera-Huarte, Francisco; Gharib, Morteza

2015-11-01

It is well known that flexibility plays an important role in the propulsion performance and efficiency of oscillating fin based propulsion systems. Compliance is one of the aspects that has received more attention, as it seems to be a common feature in nature's flyers and swimmers. Active control strategies are also common in nature. We will show how by deflecting only the last 10% of length of a rigid fin, at the tip, the thrust can be changed dramatically. This can be thought as an alternative to passive flexibility for controlling very efficiently the momentum transfer in the wake and therefore the thrust generation when flapping. A series of experiments have been carried with a robotic fin that allowed the control of its flapping kinematics as well as the control of the motions of its tip independently. We will be showing situations in which the tip was kept at a certain fixed position during a power stroke, and others in which it moved either in-phase or out-of-phase with the fin. The observed thrust and wake dynamics will be discussed for all these situations. The authors would like to acknowledge the financial support provided by the Gordon and Betty Moore Foundation and by the Spanish Ministerio de Economia y competitividad (MINECO) through grant DPI2012-37904. Visiting Associate in Aerospace, California Institute of Technology.
Active deformation and seismicity in the Southern Alps (Italy): The Montello hill as a case study

NASA Astrophysics Data System (ADS)

Danesi, Stefania; Pondrelli, Silvia; Salimbeni, Simone; Cavaliere, Adriano; Serpelloni, Enrico; Danecek, Peter; Lovati, Sara; Massa, Marco

2015-06-01

The Montello anticline is a morphotectonic feature of the east pede-mountain of the South Alpine Chain in northern Italy, which lies ca. 40 km northwest of Venice, Italy. The purpose of this study is to characterize the present-day crustal deformation and seismotectonics of the Montello area through multi-parametric geophysical observations. We used new data obtained from the installation of a temporary network of 12 seismic stations and 6 GPS sites. The GPS observations indicate that there is ~ 1 mm/yr shortening across the Montello thrust. Sites located north of the Montello thrust front deviate from the ~ NNW-ward Adria-Eurasia convergence direction, as they are constrained by a relative rotation pole in northwestern Italy that has a NNE-ward motion trend. Over 18 months, seismographic recordings allowed us to locate 142 local seismic events with Ml 0.5-3.5 with good reliability (rms < 0.5). After cross-correlation analysis, we classified 42 of these events into six clusters, with cross-correlation thresholds > 0.80. The source focal solutions indicate that: (i) there is thrusting seismic activity on the basal, sub-horizontal, portion of the Montello structure; and (ii) strike-slip source kinematics prevail on the western edge of the Montello hill. Our observations on the source mechanisms and the measured crustal deformation confirm that the Montello thrust is tectonically active.

Specificity of Postural Sway to the Demands of a Precision Task at Sea

ERIC Educational Resources Information Center

Chen, Fu-Chen; Stoffregen, Thomas A.

2012-01-01

Mariners actively adjust their body orientation in response to ship motion. On a ship at sea, we evaluated relations between standing postural activity and the performance of a precision aiming task. Standing participants (experienced mariners) maintained the beam from a handheld laser on a target. Targets were large or small, thereby varying the…
Small tractors for harvesting fuelwood in low-volume small-diameter hardwood stands

Treesearch

Neil K. Huyler; Chris B. LeDoux

1989-01-01

Much of the nonindustrial, private forest land in the Northeast is characterized by small diameter trees with low volume. Conventional harvesting systems used in logging these stands generally results in submarginal economic returns. Often, small-scale harvesting systems have economic advantages in these areas. Time and motion studies were conducted for several small...
An unconditionally stable method for numerically solving solar sail spacecraft equations of motion

NASA Astrophysics Data System (ADS)

Karwas, Alex

Solar sails use the endless supply of the Sun's radiation to propel spacecraft through space. The sails use the momentum transfer from the impinging solar radiation to provide thrust to the spacecraft while expending zero fuel. Recently, the first solar sail spacecraft, or sailcraft, named IKAROS completed a successful mission to Venus and proved the concept of solar sail propulsion. Sailcraft experimental data is difficult to gather due to the large expenses of space travel, therefore, a reliable and accurate computational method is needed to make the process more efficient. Presented in this document is a new approach to simulating solar sail spacecraft trajectories. The new method provides unconditionally stable numerical solutions for trajectory propagation and includes an improved physical description over other methods. The unconditional stability of the new method means that a unique numerical solution is always determined. The improved physical description of the trajectory provides a numerical solution and time derivatives that are continuous throughout the entire trajectory. The error of the continuous numerical solution is also known for the entire trajectory. Optimal control for maximizing thrust is also provided within the framework of the new method. Verification of the new approach is presented through a mathematical description and through numerical simulations. The mathematical description provides details of the sailcraft equations of motion, the numerical method used to solve the equations, and the formulation for implementing the equations of motion into the numerical solver. Previous work in the field is summarized to show that the new approach can act as a replacement to previous trajectory propagation methods. A code was developed to perform the simulations and it is also described in this document. Results of the simulations are compared to the flight data from the IKAROS mission. Comparison of the two sets of data show that the new approach is capable of accurately simulating sailcraft motion. Sailcraft and spacecraft simulations are compared to flight data and to other numerical solution techniques. The new formulation shows an increase in accuracy over a widely used trajectory propagation technique. Simulations for two-dimensional, three-dimensional, and variable attitude trajectories are presented to show the multiple capabilities of the new technique. An element of optimal control is also part of the new technique. An additional equation is added to the sailcraft equations of motion that maximizes thrust in a specific direction. A technical description and results of an example optimization problem are presented. The spacecraft attitude dynamics equations take the simulation a step further by providing control torques using the angular rate and acceleration outputs of the numerical formulation.
Alternations in burial and exhumation along the Selimiye (Kayabükü) shear zone in the Menderes Massif from detailed garnet pressure-temperature paths

NASA Astrophysics Data System (ADS)

Kelly, E. D.; Atakturk, K. R.; Catlos, E. J.; Lizzadro-McPherson, D. J.; Cemen, I.; Lovera, O. M.

2015-12-01

Pressure-temperature (P-T) paths derived from garnet chemical zoning and supported by thermal modeling record alternating burial and exhumation during Main Menderes Metamorphism in western Turkey. We studied six rocks along the Selimiye (Kayabükü) shear zone, three from the footwall (Çine nappe) and three from the hanging wall (Selimiye nappe). The shear zone bounds the southern Menderes Massif metamorphic core complex and has been suggested to record compression followed by extension. The rocks are lower-amphibolite facies garnet-bearing metapelites with nearly identical mineral suites. Retrograde overprinting hinders classical thermobarometry; to overcome this, preserved chemical zoning in garnet combined with a G-minimization approach was used to construct detailed P-T paths (e.g., 50 points in some paths). During continuous temperature increase, the Çine nappe paths show increasing, decreasing, and then increasing pressure (an N-shaped path) ending at 7-8 kbar and ~565-590 °C. The Selimiye nappe paths show a single increase in P-T ending at ~7.3 kbar and ~580 °C. Similar bulk-rock compositions in all samples and the separation by the shear zone suggest that garnets grew during distinct events in each nappe. The timing of garnet growth, and thus the P-T paths, is currently undetermined, as monazite inclusions in garnet appear secondary and complicated by excess common Pb. The Çine nappe N-shaped path describes alternations in burial and exhumation, possibly due to thrust motion along the shear zone. To demonstrate the physical plausibility of the P-T paths, a 2-D finite difference solution to the diffusion-advection equation was applied. The results of the thermal modeling suggest that thrusting, denudation, and renewed thrusting would produce similar changes in P-T to the N-shaped path. Thus, the Çine nappe N-shaped P-T path appears to record a gap in thrust motion along the Selimiye (Kayabükü) shear zone prior to ultimate unroofing of the massif.
Large-scale deformation related to the collision of the Aleutian Arc with Kamchatka

USGS Publications Warehouse

Gesit, Eric L.; Scholl, David W.

1994-01-01

The far western Aleutian Island Arc is actively colliding with Kamchatka. Westward motion of the Aleutian Arc is brought about by the tangential relative motion of the Pacific plate transferred to major, right-lateral shear zones north and south of the arc. Early geologic mapping of Cape Kamchatka (a promontory of Kamchatka along strike with the Aleutian Arc) revealed many similarities to the geology of the Aleutian Islands. Later studies support the notion that Cape Kamchatka is the farthest west Aleutian “island” and that it has been accreted to Kamchatka by the process of arc-continent collision. Deformation associated with the collision onshore Kamchatka includes gravimetrically determined crustal thickening and formation of a narrow thrust belt of intensely deformed rocks directly west of Cape Kamchatka. The trend of the thrust faults is concave toward the collision zone, indicating a radial distribution of maximum horizontal compressive stress. Offshore, major crustal faults trend either oblique to the Kamchatka margin or parallel to major Aleutian shear zones. These offshore faults are complex, accommodating both strike-slip and thrust displacements as documented by focal mechanisms and seismic reflection data. Earthquake activity is much higher in the offshore region within a zone bounded to the north by the northernmost Aleutian shear zone and to the west by an apparent aseismic front. Analysis of focal mechanisms in the region indicate that the present-day arc-continent “contact zone” is located directly east of Cape Kamchatka. In modeling the dynamics of the collision zone using thin viscous sheet theory, the rheological parameters are only partially constrained to values of n (the effective power law exponent) ≥ 3 and Ar(the Argand number) ≤ 30. These values are consistent with a forearc thermal profile of Kamchatka, previously determined from heat flow modeling. The thin viscous sheet modeling also indicates that onshore thrust faulting is a consequence, not only of compressive stresses resulting from the west directed collision, but also of sediment-induced coupling of the subducting Pacific plate.
An ablative pulsed plasma thruster with a segmented anode

NASA Astrophysics Data System (ADS)

Zhang, Zhe; Ren, Junxue; Tang, Haibin; Ling, William Yeong Liang; York, Thomas M.

2018-01-01

An ablative pulsed plasma thruster (APPT) design with a ‘segmented anode’ is proposed in this paper. We aim to examine the effect that this asymmetric electrode configuration (a normal cathode and a segmented anode) has on the performance of an APPT. The magnetic field of the discharge arc, plasma density in the exit plume, impulse bit, and thrust efficiency were studied using a magnetic probe, Langmuir probe, thrust stand, and mass bit measurements, respectively. When compared with conventional symmetric parallel electrodes, the segmented anode APPT shows an improvement in the impulse bit of up to 28%. The thrust efficiency is also improved by 49% (from 5.3% to 7.9% for conventional and segmented designs, respectively). Long-exposure broadband emission images of the discharge morphology show that compared with a normal anode, a segmented anode results in clear differences in the luminous discharge morphology and better collimation of the plasma. The magnetic probe data indicate that the segmented anode APPT exhibits a higher current density in the discharge arc. Furthermore, Langmuir probe data collected from the central exit plane show that the peak electron density is 75% higher than with conventional parallel electrodes. These results are believed to be fundamental to the physical mechanisms behind the increased impulse bit of an APPT with a segmented electrode.
Preliminary dynamic tests of a flight-type ejector

NASA Technical Reports Server (NTRS)

Drummond, Colin K.

1992-01-01

A thrust augmenting ejector was tested to provide experimental data to assist in the assessment of theoretical models to predict duct and ejector fluid-dynamic characteristics. Eleven full-scale thrust augmenting ejector tests were conducted in which a rapid increase in the ejector nozzle pressure ratio was effected through a unique facility, bypass/burst-disk subsystem. The present work examines two cases representative of the test performance window. In the first case, the primary nozzle pressure ration (NPR) increased 36 percent from one unchoked (NPR = 1.29) primary flow condition to another (NPR = 1.75) over a 0.15 second interval. The second case involves choked primary flow conditions, where a 17 percent increase in primary nozzle flowrate (from NPR = 2.35 to NPR = 2.77) occurred over approximately 0.1 seconds. Although the real-time signal measurements support qualitative remarks on ejector performance, extracting quantitative ejector dynamic response was impeded by excessive aerodynamic noise and thrust stand dynamic (resonance) characteristics. It does appear, however, that a quasi-steady performance assumption is valid for this model with primary nozzle pressure increased on the order of 50 lb(sub f)/s. Transient signal treatment of the present dataset is discussed and initial interpretations of the results are compared with theoretical predictions for a similar Short Takeoff and Vertical Landing (STOVL) ejector model.
Elimination of High-Frequency Combustion Instability in the Fastrac Engine Thrust Chamber

NASA Technical Reports Server (NTRS)

Rocker, Marvin; Nesman, Thomas E.

1998-01-01

NASA's Marshall Space Flight Center(MSFC) has been tasked with developing a 60,000 pound thrust, pump-fed, LOX/RP-1 engine under the Advanced Space Transportation Program(ASTP). This government-led design has been designated the Fastrac engine. The X-34 vehicle will use the Fastrac engine as the main propulsion system. The X-34 will be a suborbital vehicle developed by the Orbital Sciences Corporation. The X-34 vehicle will be launched from an L-1011 airliner. After launch, the X-34 vehicle will be able to climb to altitudes up to 250,000 feet and reach speeds up to Mach 8, over a mission range of 500 miles. The overall length, wingspan, and gross takeoff weight of the X-34 vehicle are 58.3 feet, 27.7 feet and 45,000 pounds, respectively. This report summarizes the plan of achieving a Fastrac thrust chamber assembly(TCA) stable bomb test that meets the JANNAF standards, the Fastrac TCA design, and the combustion instabilities exhibited by the Fastrac TCA during testing at MSFC's test stand 116 as determined from high-frequency fluctuating pressure measurements. This report also summarizes the characterization of the combustion instabilities from the pressure measurements and the steps taken to eliminate the instabilities.
Real-time positioning in logging: Effects of forest stand characteristics, topography, and line-of-sight obstructions on GNSS-RF transponder accuracy and radio signal propagation.

PubMed

Zimbelman, Eloise G; Keefe, Robert F

2018-01-01

Real-time positioning on mobile devices using global navigation satellite system (GNSS) technology paired with radio frequency (RF) transmission (GNSS-RF) may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio propagation of GNSS locations may also be impacted due to line-of-sight (LOS) obstruction in remote, forested areas. The objective of this study was to characterize the effects of forest stand characteristics, topography, and other LOS obstructions on the GNSS accuracy and radio signal propagation quality of multiple Raveon Atlas PT GNSS-RF transponders functioning as a network in a range of forest conditions. Because most previous research with GNSS in forestry has focused on stationary units, we chose to analyze units in motion by evaluating the time-to-signal accuracy of geofence crossings in 21 randomly-selected stands on the University of Idaho Experimental Forest. Specifically, we studied the effects of forest stand characteristics, topography, and LOS obstructions on (1) the odds of missed GNSS-RF signals, (2) the root mean squared error (RMSE) of Atlas PTs, and (3) the time-to-signal accuracy of safety geofence crossings in forested environments. Mixed-effects models used to analyze the data showed that stand characteristics, topography, and obstructions in the LOS affected the odds of missed radio signals while stand variables alone affected RMSE. Both stand characteristics and topography affected the accuracy of geofence alerts.
Real-time positioning in logging: Effects of forest stand characteristics, topography, and line-of-sight obstructions on GNSS-RF transponder accuracy and radio signal propagation

PubMed Central

2018-01-01

Real-time positioning on mobile devices using global navigation satellite system (GNSS) technology paired with radio frequency (RF) transmission (GNSS-RF) may help to improve safety on logging operations by increasing situational awareness. However, GNSS positional accuracy for ground workers in motion may be reduced by multipath error, satellite signal obstruction, or other factors. Radio propagation of GNSS locations may also be impacted due to line-of-sight (LOS) obstruction in remote, forested areas. The objective of this study was to characterize the effects of forest stand characteristics, topography, and other LOS obstructions on the GNSS accuracy and radio signal propagation quality of multiple Raveon Atlas PT GNSS-RF transponders functioning as a network in a range of forest conditions. Because most previous research with GNSS in forestry has focused on stationary units, we chose to analyze units in motion by evaluating the time-to-signal accuracy of geofence crossings in 21 randomly-selected stands on the University of Idaho Experimental Forest. Specifically, we studied the effects of forest stand characteristics, topography, and LOS obstructions on (1) the odds of missed GNSS-RF signals, (2) the root mean squared error (RMSE) of Atlas PTs, and (3) the time-to-signal accuracy of safety geofence crossings in forested environments. Mixed-effects models used to analyze the data showed that stand characteristics, topography, and obstructions in the LOS affected the odds of missed radio signals while stand variables alone affected RMSE. Both stand characteristics and topography affected the accuracy of geofence alerts. PMID:29324794
Time-Resolved Quantitative Analysis of the Diaphragms During Tidal Breathing in a Standing Position Using Dynamic Chest Radiography with a Flat Panel Detector System ("Dynamic X-Ray Phrenicography"): Initial Experience in 172 Volunteers.

PubMed

Yamada, Yoshitake; Ueyama, Masako; Abe, Takehiko; Araki, Tetsuro; Abe, Takayuki; Nishino, Mizuki; Jinzaki, Masahiro; Hatabu, Hiroto; Kudoh, Shoji

2017-04-01

Diaphragmatic motion in a standing position during tidal breathing remains unclear. The purpose of this observational study was to evaluate diaphragmatic motion during tidal breathing in a standing position in a health screening center cohort using dynamic chest radiography in association with participants' demographic characteristics. One hundred seventy-two subjects (103 men; aged 56.3 ± 9.8 years) underwent sequential chest radiographs during tidal breathing using dynamic chest radiography with a flat panel detector system. We evaluated the excursions of and peak motion speeds of the diaphragms. Associations between the excursions and participants' demographics (gender, height, weight, body mass index [BMI], smoking history, tidal volume, vital capacity, and forced expiratory volume) were investigated. The average excursion of the left diaphragm (14.9 ± 4.6 mm, 95% CI 14.2-15.5 mm) was significantly larger than that of the right (11.0 ± 4.0 mm, 95% CI 10.4-11.6 mm) (P <0.001). The peak motion speed of the left diaphragm (inspiratory, 16.6 ± 4.2 mm/s; expiratory, 13.7 ± 4.2 mm/s) was significantly faster than that of the right (inspiratory, 12.4 ± 4.4 mm/s; expiratory, 9.4 ± 3.8 mm/s) (both P <0.001). Both simple and multiple regression models demonstrated that higher BMI and higher tidal volume were associated with increased excursions of the bilateral diaphragm (all P <0.05). The average excursions of the diaphragms are 11.0 mm (right) and 14.9 mm (left) during tidal breathing in a standing position. The diaphragmatic motion of the left is significantly larger and faster than that of the right. Higher BMI and tidal volume are associated with increased excursions of the bilateral diaphragm. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.
Optimal propulsive flapping in Stokes flows.

PubMed

Was, Loïc; Lauga, Eric

2014-03-01

Swimming fish and flying insects use the flapping of fins and wings to generate thrust. In contrast, microscopic organisms typically deform their appendages in a wavelike fashion. Since a flapping motion with two degrees of freedom is able, in theory, to produce net forces from a time-periodic actuation at all Reynolds numbers, we compute in this paper the optimal flapping kinematics of a rigid spheroid in a Stokes flow. The hydrodynamics for the force generation and energetics of the flapping motion is solved exactly. We then compute analytically the gradient of a flapping efficiency in the space of all flapping gaits and employ it to derive numerically the optimal flapping kinematics as a function of the shape of the flapper and the amplitude of the motion. The kinematics of optimal flapping are observed to depend weakly on the flapper shape and are very similar to the figure-eight motion observed in the motion of insect wings. Our results suggest that flapping could be a exploited experimentally as a propulsion mechanism valid across the whole range of Reynolds numbers.
Actuation control of a PiezoMEMS biomimetic robotic jellyfish

NASA Astrophysics Data System (ADS)

Alejandre, Alvaro; Olszewski, Oskar; Jackson, Nathan

2017-06-01

Biomimetic micro-robots try to mimic the motion of a living system in the form of a synthetically developed microfabricated device. Dynamic motion of living systems have evolved through the years, but trying to mimic these motions is challenging. Micro-robotics are particular challenging as the fabrication of devices and controlling the motion in 3 dimensions is difficult. However, micro-scale robotics have potential to be used in a wide range of applications. MEMS based robots that can move and function in a liquid environment is of particular interest. This paper describes the development of a piezoMEMS based device that mimics the movement of a jellyfish. The paper focuses on the development of a finite element model that investigates a method of controlling the individual piezoelectric beams in order to create a jet propulsion motion, consisting of a quick excitation pulse followed by a slow recovery pulse in order to maximize thrust and velocity. By controlling the individual beams or legs of the jellyfish robot the authors can control the robot to move precisely in 3 dimensions.
Evaluation of the recorded ground motions for the unusual earthquake of 13 August 2006 ( M w 5.3) in Michoacán México

NASA Astrophysics Data System (ADS)

Ramírez-Gaytán, Alejandro; Jaimes, Miguel A.; Bandy, William L.; Huerfano, Victor M.; Salido-Ruiz, Ricardo A.

2015-10-01

The focal mechanism of the moderate earthquake of 13 August 2006 M w = 5.3, which occurred in the border coastal area between Michoacán and Colima, México, is unusual. As shown by the Global Centroid Moment Tensor (CMT) project and the Servicio Sismológico Nacional de Mexico (SSN), the thrust mechanism is striking almost perpendicularly to the majority of earthquakes occurring along the subduction zone of the Mexican Pacific continental margin which commonly strike nearly parallel to the trench. The purpose of this study is to analyze the observed ground motions of this particular event relative to those of the common events. First, we apply the H/V technique to verify that the stations involved in this study are nearly free of site effects. Then, we compare the observed ground motions with (i) three empirical ground motion prediction equations (GMPEs) appropriate for the region, (ii) ground motions of four real earthquakes with the common mechanism, and (iii) the Fourier spectrum of a selected common event.
Around Marshall

NASA Image and Video Library

1963-09-18

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In addition to the stand itself, related facilities were constructed during this time. This photograph taken September 18, 1963 shows a spherical hydrogen tank being constructed next to the S-IC test stand.
Design and application of electromechanical actuators for deep space missions

NASA Technical Reports Server (NTRS)

Haskew, Tim A.; Wander, John

1994-01-01

This progress report documents research and development efforts performed from August 16, 1993 through August 15, 1994 on NASA Grant NAG8-240, 'Design and Application of Electromechanical Actuators for Deep Space Missions.' Since the submission of our last progress report in February 1994, our efforts have been almost entirely focused on final construction of the test stand and experiment design. Hence, this report is dedicated solely to these topics. However, updates on our research personnel and our health monitoring and fault management efforts are provided in this summary. Following this executive summary are two report sections. The first is devoted to the motor drive being constructed for the test stand. The thrust of the next section is the mechanical and hydraulic design and construction based on the planned experimental requirements. Following both major sections are three appendices.
Enhanced thrust and speed revealed in the forward flight of a butterfly with transient body translation.

PubMed

Fei, Yueh-Han John; Yang, Jing-Tang

2015-09-01

A butterfly with broad wings, flapping at a small frequency, flies an erratic trajectory at an inconstant speed. A large variation of speed within a cycle is observed in the forward flight of a butterfly. A self-propulsion model to simulate a butterfly is thus created to investigate the transient translation of the body; the results, which are in accordance with experimental data, show that the shape of the variation of the flight speed is similar to a sinusoidal wave with a maximum (J=0.89) at the beginning of the downstroke, and a decrease to a minimum (J=0.17) during a transition from downstroke to upstroke; the difference between the extrema of the flight speed is enormous in a flapping cycle. At a high speed, a clapping motion of the butterfly wings decreases the generation of drag. At a small speed, a butterfly is able to capture the induced wakes generated in a downstroke, and effectively generates a thrust at the beginning of an upstroke. The wing motion of a butterfly skillfully interacts with its speed so as to enable an increased speed with the same motion. Considering a butterfly to fly in a constant inflow leads to either an underestimate of its speed or an overestimate of its generated lift, which yields an inaccurate interpretation of the insect's flight. Our results reveal the effect of transient translation on a butterfly in forward flight, which is especially important for an insect with a small flapping frequency.
Enhanced thrust and speed revealed in the forward flight of a butterfly with transient body translation

NASA Astrophysics Data System (ADS)

Fei, Yueh-Han John; Yang, Jing-Tang

2015-09-01

A butterfly with broad wings, flapping at a small frequency, flies an erratic trajectory at an inconstant speed. A large variation of speed within a cycle is observed in the forward flight of a butterfly. A self-propulsion model to simulate a butterfly is thus created to investigate the transient translation of the body; the results, which are in accordance with experimental data, show that the shape of the variation of the flight speed is similar to a sinusoidal wave with a maximum (J =0.89 ) at the beginning of the downstroke, and a decrease to a minimum (J =0.17 ) during a transition from downstroke to upstroke; the difference between the extrema of the flight speed is enormous in a flapping cycle. At a high speed, a clapping motion of the butterfly wings decreases the generation of drag. At a small speed, a butterfly is able to capture the induced wakes generated in a downstroke, and effectively generates a thrust at the beginning of an upstroke. The wing motion of a butterfly skillfully interacts with its speed so as to enable an increased speed with the same motion. Considering a butterfly to fly in a constant inflow leads to either an underestimate of its speed or an overestimate of its generated lift, which yields an inaccurate interpretation of the insect's flight. Our results reveal the effect of transient translation on a butterfly in forward flight, which is especially important for an insect with a small flapping frequency.
Influence of Wall Porosity and Surfaces Roughness on the Steady Performance of an Externally Pressurized Hydrostatic Conical Bearing Lubricated by a Rabinowitsch Fluid

NASA Astrophysics Data System (ADS)

Walicka, A.; Walicki, E.; Jurczak, P.; Falicki, J.

2017-08-01

In the paper, the influence of both the bearing surfaces roughness as well as porosity of one bearing surface on the pressure distribution and load-carrying capacity of a curvilinear, externally pressurized, thrust bearing is discussed. The equations of motion of a pseudo-plastic Rabinowitsch fluid are used to derive the Reynolds equation. After general considerations on the flow in a bearing clearance and in a porous layer using the Morgan-Cameron approximation and Christensen theory of hydrodynamic lubrication with rough bearing surfaces the modified Reynolds equation is obtained. The analytical solution is presented; as a result one obtains the formulae expressing the pressure distribution and load-carrying capacity. Thrust radial and conical bearings, externally pressurized, are considered as numerical examples.
Seismicity of the Earth 1900-2010 New Guinea and vicinity

USGS Publications Warehouse

Benz, Harley M.; Herman, Matthew; Tarr, Arthur C.; Hayes, Gavin P.; Furlong, Kevin P.; Villaseñor, Antonio; Dart, Richard L.; Rhea, Susan

2011-01-01

There have been 22 M7.5+ earthquakes recorded in the New Guinea region since 1900. The dominant earthquake mechanisms are thrust and strike slip, associated with the arc-continent collision and the relative motions between numerous local microplates. The largest earthquake in the region was a M8.2 shallow thrust fault event in the northern Papua province of Indonesia that killed 166 people in 1996. The Australia-Pacific plate boundary is over 4,000 km long on the northern margin, from the Sunda (Java) trench in the west to the Solomon Islands in the east. The eastern section is over 2,300 km long, extending west from northeast of the Australian continent and the Coral Sea until it intersects the east coast of Papua New Guinea. The boundary is dominated by the general northward subduction of the Australia plate.

Pulsed plasmoid electric propulsion

NASA Technical Reports Server (NTRS)

Bourque, Robert F.; Parks, Paul B.; Tamano, Teruo

1990-01-01

A method of electric propulsion is explored where plasmoids such as spheromaks and field reversed configurations (FRC) are formed and then allowed to expand down a diverging conducting shell. The plasmoids contain a toroidal electric current that provides both heating and a confining magnetic field. They are free to translate because there are no externally supplied magnetic fields that would restrict motion. Image currents in the diverging conducting shell keep the plasmoids from contacting the wall. Because these currents translate relative to the wall, losses due to magnetic flux diffusion into the wall are minimized. During the expansion of the plasma in the diverging cone, both the inductive and thermal plasma energy are converted to directed kinetic energy producing thrust. Specific impulses can be in the 4000 to 20000 sec range with thrusts from 0.1 to 1000 Newtons, depending on available power.
Design and Fabrication of Soft Morphing Ray Propulsor: Undulator and Oscillator.

PubMed

Kim, Hyung-Soo; Lee, Jang-Yeob; Chu, Won-Shik; Ahn, Sung-Hoon

2017-03-01

A soft morphing ray propulsor capable of generating an undulating motion in its pectoral fins was designed and fabricated. The propulsor used shape memory alloy for actuation, and the body was made with soft polymers. To determine the effects of undulation in the fins, two models that differed in terms of the presence of undulation were fabricated using different polymer materials. The experimental models were tested with a dynamometer to measure and compare thrust tendencies. Thrust measurements were conducted with various fin beat frequencies. Using the experimental data, the concept of an optimized standalone version of the ray robot was suggested and its prototype was fabricated. The fabricated robot was able to swim as fast as 0.26 body length per second and 38% more efficient than other smart material-based ray-like underwater robots.
Numerical Simulation of Strong Ground Motion at Mexico City:A Hybrid Approach for Efficient Evaluation of Site Amplification and Path Effects for Different Types of Earthquakes

NASA Astrophysics Data System (ADS)

Cruz, H.; Furumura, T.; Chavez-Garcia, F. J.

2002-12-01

The estimation of scenarios of the strong ground motions caused by future great earthquakes is an important problem in strong motion seismology. This was pointed out by the great 1985 Michoacan earthquake, which caused a great damage in Mexico City, 300 km away from the epicenter. Since the seismic wavefield is characterized by the source, path and site effects, the pattern of strong motion damage from different types of earthquakes should differ significantly. In this study, the scenarios for intermediate-depth normal-faulting, shallow-interplate thrust faulting, and crustal earthquakes have been estimated using a hybrid simulation technique. The character of the seismic wavefield propagating from the source to Mexico City for each earthquake was first calculated using the pseudospectral method for 2D SH waves. The site amplifications in the shallow structure of Mexico City are then calculated using the multiple SH wave reverberation theory. The scenarios of maximum ground motion for both inslab and interplate earthquakes obtained by the simulation show a good agreement with the observations. This indicates the effectiveness of the hybrid simulation approach to investigate the strong motion damage for future earthquakes.
Anatomical Calibration through Post-Processing of Standard Motion Tests Data.

PubMed

Kong, Weisheng; Sessa, Salvatore; Zecca, Massimiliano; Takanishi, Atsuo

2016-11-28

The inertial measurement unit is popularly used as a wearable and flexible tool for human motion tracking. Sensor-to-body alignment, or anatomical calibration (AC), is fundamental to improve accuracy and reliability. Current AC methods either require extra movements or are limited to specific joints. In this research, the authors propose a novel method to achieve AC from standard motion tests (such as walking, or sit-to-stand), and compare the results with the AC obtained from specially designed movements. The proposed method uses the limited acceleration range on medial-lateral direction, and applies principal component analysis to estimate the sagittal plane, while the vertical direction is estimated from acceleration during quiet stance. The results show a good correlation between the two sets of IMUs placed on frontal/back and lateral sides of head, trunk and lower limbs. Moreover, repeatability and convergence were verified. The AC obtained from sit-to-stand and walking achieved similar results as the movements specifically designed for upper and lower body AC, respectively, except for the feet. Therefore, the experiments without AC performed can be recovered through post-processing on the walking and sit-to-stand data. Moreover, extra movements for AC can be avoided during the experiment and instead achieved through the proposed method.
Short-term combined effects of thoracic spine thrust manipulation and cervical spine nonthrust manipulation in individuals with mechanical neck pain: a randomized clinical trial.

PubMed

Masaracchio, Michael; Cleland, Joshua A; Hellman, Madeleine; Hagins, Marshall

2013-03-01

Randomized clinical trial. To investigate the short-term effects of thoracic spine thrust manipulation combined with cervical spine nonthrust manipulation (experimental group) versus cervical spine nonthrust manipulation alone (comparison group) in individuals with mechanical neck pain. Research has demonstrated improved outcomes with both nonthrust manipulation directed at the cervical spine and thrust manipulation directed at the thoracic spine in patients with neck pain. Previous studies have not determined if thoracic spine thrust manipulation may increase benefits beyond those provided by cervical nonthrust manipulation alone. Sixty-four participants with mechanical neck pain were randomized into 1 of 2 groups, an experimental or comparison group. Both groups received 2 treatment sessions of cervical spine nonthrust manipulation and a home exercise program consisting of active range-of-motion exercises, and the experimental group received additional thoracic spine thrust manipulations. Outcome measures were collected at baseline and at a 1-week follow-up, and included the numeric pain rating scale, the Neck Disability Index, and the global rating of change. Participants in the experimental group demonstrated significantly greater improvements (P<.001) on both the numeric pain rating scale and Neck Disability Index at the 1-week follow-up compared to those in the comparison group. In addition, 31 of 33 (94%) participants in the experimental group, compared to 11 of 31 participants (35%) in the comparison group, indicated a global rating of change score of +4 or higher at the 1-week follow-up, with an associated number needed to treat of 2. Individuals with neck pain who received a combination of thoracic spine thrust manipulation and cervical spine nonthrust manipulation plus exercise demonstrated better overall short-term outcomes on the numeric pain rating scale, the Neck Disability Index, and the global rating of change.
Feasibility study of an aerial manipulator interacting with a vertical wall

DTIC Science & Technology

2017-06-01

each blade . Some tests are run with different levels of PWM input and the resultant angular acceleration in each case is measured with the motion...Helicopter Near a Vertical Surface ...................29 Figure 15. Near-Wall Moment for a Single Blade Helicopter. Source: [30]. .............30...with canted propellers is proposed, so that each blade applies thrust with components in the vertical and in the horizontal plane. In Figure 10
Mechanical Mixer for Rudder/Braking Wedge

NASA Technical Reports Server (NTRS)

Grimm, D.

1985-01-01

Right and left rudder panels moved separately. Mechanical mixer enables panels of two-panel rudder to rotate in same direction for steering or in opposite directions for dynamic braking. Steering and braking inputs separate so any combination of steering and braking motions executed simultaneously. Developed for aerodynamic braking of Space Shuttle orbiter, steering/braking drive train and rudder arrangement used for similar purposes on aircraft, thereby reducing sizes of thrust reversers.
Modeling stick-slip-separation dynamics in a bimodal standing wave ultrasonic motor

NASA Astrophysics Data System (ADS)

Li, Xiang; Yao, Zhiyuan; Lv, Qibao; Liu, Zhen

2016-11-01

Ultrasonic motor (USM) is an electromechanical coupling system with ultrasonic vibration, which is driven by the frictional contact force between the stator (vibrating body) and the rotor/slider (driven body). Stick-slip motion can occur at the contact interface when USM is operating, which may affect the performance of the motor. This paper develops a physically-based model to investigate the complex stick-slip-separation dynamics in a bimodal standing wave ultrasonic motor. The model includes both friction nonlinearity and intermittent separation nonlinearity of the system. Utilizing Hamilton's principle and assumed mode method, the dynamic equations of the stator are deduced. Based on the dynamics of the stator and the slider, sticking force during the stick phase is derived, which is used to examine the stick-to-slip transition. Furthermore, the stick-slip-separation kinematics is analyzed by establishing analytical criteria that predict the transition between stick, slip and separation of the interface. Stick-slip-separation motion is observed in the resulting model, and numerical simulations are performed to study the influence of parameters on the range of possible motions. Results show that stick-slip motion can occur with greater preload and smaller voltage amplitude. Furthermore, a dimensionless parameter is proposed to predict the occurrence of stick-slip versus slip-separation motions, and its role in designing ultrasonic motors is discussed. It is shown that slip-separation motion is favorable for the slider velocity.
Loss estimates for a Puente Hills blind-thrust earthquake in Los Angeles, California

USGS Publications Warehouse

Field, E.H.; Seligson, H.A.; Gupta, N.; Gupta, V.; Jordan, T.H.; Campbell, K.W.

2005-01-01

Based on OpenSHA and HAZUS-MH, we present loss estimates for an earthquake rupture on the recently identified Puente Hills blind-thrust fault beneath Los Angeles. Given a range of possible magnitudes and ground motion models, and presuming a full fault rupture, we estimate the total economic loss to be between $82 and $252 billion. This range is not only considerably higher than a previous estimate of $69 billion, but also implies the event would be the costliest disaster in U.S. history. The analysis has also provided the following predictions: 3,000-18,000 fatalities, 142,000-735,000 displaced households, 42,000-211,000 in need of short-term public shelter, and 30,000-99,000 tons of debris generated. Finally, we show that the choice of ground motion model can be more influential than the earthquake magnitude, and that reducing this epistemic uncertainty (e.g., via model improvement and/or rejection) could reduce the uncertainty of the loss estimates by up to a factor of two. We note that a full Puente Hills fault rupture is a rare event (once every ???3,000 years), and that other seismic sources pose significant risk as well. ?? 2005, Earthquake Engineering Research Institute.
A slab expression in the Gibraltar arc?

NASA Astrophysics Data System (ADS)

Nijholt, Nicolai; Govers, Rob; Wortel, Rinus

2017-04-01

The present-day geodynamic setting of the Gibraltar arc region results from several Myrs of subduction rollback in the overall (oblique) convergence of Africa and Iberia. As for most rollback settings in a convergence zone, the interaction of these two components is complex and distinctly non-stationary. Gibraltar slab rollback is considered to have stalled, or at least diminished largely in magnitude, since the late Miocene/early Pliocene, suggesting that the effect of the slab on present-day surface motions is negligible. However, GPS measurements indicate that the Gibraltar arc region has an anomalous motion with respect to both Iberia and Africa, i.e., the Gibraltar arc region does not move as part of the rigid Iberian, or the rigid African plate. A key question is whether this surface motion is an expression of the Gibraltar slab. Seismic activity in the Gibraltar region is diffuse and considerable in magnitude, making it a region of high seismic risk. Unlike the North African margin to the east, where thrust earthquakes dominate the focal mechanism tables, a complex pattern is observed with thrust, normal and strike-slip earthquakes in a region stretching between the northern Moroccan Atlas across the Gibraltar arc and Alboran Sea (with the Trans-Alboran Shear Zone) to the Betics of southern Spain. Even though no large mega-thrust earthquakes have been observed in recent history, slab rollback may not have completely ceased. However, since no activity has been observed in the accretionary wedge, probably since the Pliocene, it is likely that the subduction interface is locked. In this study, we perform a series of numerical models in which we combine the relative plate convergence, variable magnitude of friction on fault segments, regional variations in gravitational potential energy and slab pull of the Gibraltar slab. We seek to reproduce the GPS velocities and slip sense on regional faults and thereby determine whether the Gibraltar slab has an effect on surface motion. Slab shape and slab continuity to the surface, allowing slab pull to be transfered to the surface lithosphere, are key factors controlling the force balance in the region. We explore slab geometries with or without continuity at the Betics (with a slab window between the known subduction interface and a possible Betics connection) and/or continental material attached to the slab (which lowers the slab pull magnitude). Through our methodology, we are able to study which slab shape of those proposed in the literature best fits the surface data.
DROMO formulation for planar motions: solution to the Tsien problem

NASA Astrophysics Data System (ADS)

Urrutxua, Hodei; Morante, David; Sanjurjo-Rivo, Manuel; Peláez, Jesús

2015-06-01

The two-body problem subject to a constant radial thrust is analyzed as a planar motion. The description of the problem is performed in terms of three perturbation methods: DROMO and two others due to Deprit. All of them rely on Hansen's ideal frame concept. An explicit, analytic, closed-form solution is obtained for this problem when the initial orbit is circular (Tsien problem), based on the DROMO special perturbation method, and expressed in terms of elliptic integral functions. The analytical solution to the Tsien problem is later used as a reference to test the numerical performance of various orbit propagation methods, including DROMO and Deprit methods, as well as Cowell and Kustaanheimo-Stiefel methods.
Flapping Wings of an Inclined Stroke Angle: Experiments and Reduced-Order Models in Dual Aerial/Aquatic Flight

NASA Astrophysics Data System (ADS)

Izraelevitz, Jacob; Triantafyllou, Michael

2016-11-01

Flapping wings in nature demonstrate a large force actuation envelope, with capabilities beyond the limits of static airfoil section coefficients. Puffins, guillemots, and other auks particularly showcase this mechanism, as they are able to both generate both enough thrust to swim and lift to fly, using the same wing, by changing the wing motion trajectory. The wing trajectory is therefore an additional design criterion to be optimized along with traditional aircraft parameters, and could possibly enable dual aerial/aquatic flight. We showcase finite aspect-ratio flapping wing experiments, dynamic similarity arguments, and reduced-order models for predicting the performance of flapping wings that carry out complex motion trajectories.
The South Tibet detachment shear zone in the Dinggye area. Time constraints on extrusion models of the Himalayas

NASA Astrophysics Data System (ADS)

Leloup, P. H.; Mahéo, G.; Arnaud, N.; Kali, E.; Boutonnet, E.; Liu, Dunyi; Xiaohan, Liu; Haibing, Li

2010-03-01

We investigate the timing of end of motion along the South Tibet Detachment System (STDS), a major normal fault system that runs parallel to the Himalayan range for more than 1500 km. Near Dinggye (˜ 28°10'N, 87°40'E), the STD dips ˜ 10 ± 5° to the North and separates Paleozoic Tethyan series from Upper Himalayan Crystalline Series (UHCS). Immediately below the STD, the UHCS is highly deformed in the STD shear zone, lineations trend NNE and the shear senses are top to the NE. In micaschist, the P-T path constrained by pseudosection and garnet chemistry, shows successive metamorphic conditions of ˜ 0.6 GPa and ˜ 550 °C and 0.5 GPa and 625 °C. U/Pb dating of monazites and zircons in deformed and undeformed leucogranites suggests that ductile deformation lasted until at least ˜ 16 Ma but ended prior to ˜ 15 Ma in the STD shear zone ˜ 100 m below the detachment. Ar/Ar micas ages in the footwall span between ˜ 14.6 and 13.6 Ma, indicating rapid cooling down to ˜ 320 °C, and suggesting persistence of normal faulting, at that time. The STDS is cut and offset by the N-S trending Dinggye active normal fault which initiated prior to 11 Ma thus providing a minimum bound for the end of STDS motion. These data are interpreted as reflecting 0.3 GPa (11 km) to 0.6 GPa (22 km) of exhumation along the STDS starting prior to ˜ 16 Ma, ending between 13.6 and 11 Ma. The 1000 km long stretch of the STDS east of the Gurla Mandata probably stopped almost synchronously between 13 and 11 Ma ago, coevally with a sudden switch from NNE-SSW to E-W extension at the top of the accretionary prism, with a jump of the major thrust from the lower Main Central Thrust (MCTl) to the Main Boundary Thrust (MBT), and with a change in the India and Asia convergence direction. This synchronism is probably better explained in the frame of a thrust wedge or thrust system model than a lower channel flow model. West of the Gurla Mandata the STDS appears to stop 5 to 3 Ma earlier, possibly related to local interactions with the Karakorum fault in a way that needs to be understood.
Postural Responses to a Moving Room in Children with and without Developmental Coordination Disorder

ERIC Educational Resources Information Center

Chung, Hyun Chae; Stoffregen, Thomas A.

2011-01-01

Children (10 or 11 years old) with and without developmental coordination disorder (DCD) were exposed to imposed optic flow in a moving room. We manipulated the amplitude and frequency of oscillatory room motion, and we evaluated the coupling of standing body sway with room oscillations. The results revealed that standing sway of both children…
Impact of alternative harvesting technologies on thinning entry and optimal rotation age for eastern hardwoods

Treesearch

Chris B. LeDoux

2007-01-01

A complete system simulation model is used to integrate alternative logging technologies, stand data, market prices, transportation costs, and economic concerns in a longterm continuous manner to evaluate thinning entry timing and optimal rotation age. Forest Inventory and Analysis (FIA) stand data for the oak/hickory forest type and time and motion study data for 70,...
Harvesting short rotation woody crops with a shear

Treesearch

Wellington Cardoso; Dana Mitchell; Tom Gallagher; Daniel and de Souza

2014-01-01

A time and motion study was performed on a skid steer equipped with a 14-inch tree shear attachment. The machine was used to install initial coppice harvesting treatments on three stands across the south. The study included one willow and two cottonwood sites. The stands averaged from 2 to 4 years old. Approximately 200 trees were shear harvested from each of the...
Hip and knee effects after implantation of a drop foot stimulator.

PubMed

Yao, Daiwei; Lahner, Matthias; Jakubowitz, Eike; Thomann, Anna; Ettinger, Sarah; Noll, Yvonne; Stukenborg-Colsman, Christina; Daniilidis, Kiriakos

2017-01-01

An active ankle dorsiflexion is essential for a proper gait pattern. If there is a failure of the foot lifting, considerable impairments occur. The therapeutic effect of an implantable peroneus nerve stimulator (iPNS) for the ankle dorsiflexion is already approved by recent studies. However, possible affection for knee and hip motion after implantation of an iPNS is not well described. The objective of this retrospective study was to examine with a patient cohort whether the use of iPNS induces a lower-extremity flexion withdrawal response in the form of an increased knee and hip flexion during swing phase. Eighteen subjects (12 m/6 w) treated with an iPNS (ActiGait®, Otto Bock, Duderstadt, Germany) were examined in knee and hip motion by gait analysis with motion capture system (Vicon Motion System Ltd®, Oxford, UK) and Plug-in-Gait model after a mean follow up from 12.5 months. The data were evaluated and compared in activated and deactivated iPNS. Only little changes could be documented, as a slight average improvement in peak knee flexion during stand phase from 1.0° to 2.5° and peak hip flexion in stance from 3.1° to 2.1° In contrast, peak knee flexion during swing appeared similar (25.3° to 25.7°) same as peak hip flexion during swing. In comparison with the healthy extremity, a more symmetric course of the knee flexion during stand phase could be shown. No statistical significant improvements or changes in hip and knee joint could be shown in this study. Only a more symmetric knee flexion during stand phase and a less hip flexion during stand phase might be hints for a positive affection of iPNS for knee and hip joint. It seems that the positive effect of iPNS is only based on the improvement in ankle dorsiflexion according to the recent literature.
Computer-assisted time-averaged holograms of the motion of the surface of the mammalian tympanic membrane with sound stimuli of 0.4 to 25 kHz

PubMed Central

Rosowski, John J.; Cheng, Jeffrey Tao; Ravicz, Michael E.; Hulli, Nesim; Hernandez-Montes, Maria; Harrington, Ellery; Furlong, Cosme

2009-01-01

Time-averaged holograms describing the sound-induced motion of the tympanic membrane (TM) in cadaveric preparations from three mammalian species and one live ear were measured using opto-electronic holography. This technique allows rapid measurements of the magnitude of motion of the tympanic membrane surface at frequencies as high as 25 kHz. The holograms measured in response to low and middle-frequency sound stimuli are similar to previously reported time-averaged holograms. However, at higher frequencies (f > 4 kHz), our holograms reveal unique TM surface displacement patterns that consist of highly-ordered arrangements of multiple local displacement magnitude maxima, each of which is surrounded by nodal areas of low displacement magnitude. These patterns are similar to modal patterns (two-dimensional standing waves) produced by either the interaction of surface waves traveling in multiple directions or the uniform stimulation of modes of motion that are determined by the structural properties and boundary conditions of the TM. From the ratio of the displacement magnitude peaks to nodal valleys in these apparent surface waves, we estimate a Standing Wave Ratio of at least 4 that is consistent with energy reflection coefficients at the TM boundaries of at least 0.35. It is also consistent with small losses within the uniformly stimulated modal surface waves. We also estimate possible TM surface wave speeds that vary with frequency and species from 20 to 65 m/s, consistent with other estimates in the literature. The presence of standing wave or modal phenomena has previously been intuited from measurements of TM function, but is ignored in some models of tympanic membrane function. Whether these standing waves result either from the interactions of multiple surface waves that travel along the membrane, or by uniformly excited modal displacement patterns of the entire TM surface is still to be determined. PMID:19328841
Goniometric measurement of hip motion in cycling while standing.

PubMed

Hull, M L; Beard, A; Varma, H

1990-01-01

The purpose of this study was to develop an instrument for quantifying the motion of the hip relative to the bicycle while cycling in the standing position. Because of the need to measure hip motion on the road as well as in the laboratory, a goniometer which locates the hip using spherical coordinates was designed. The goniometer is presented first, followed by the development of the equations that enable the distance from the joint center to the pedal spindle to be determined. The orientation of this line segment is specified by calculating two angles referenced to the frame. Also outlined are the procedures used to both calibrate the goniometer and perform an accuracy check. The results of this check indicate that the attachment point of the goniometer to the rider can be located to within 2.5 mm of the true position. The goniometer was used to record the hip movement patterns of six subjects who cycled in the standing position on a treadmill. Representative results from one test subject who cycled at 6% grade and 25 km h-1 are presented. Results indicate that the bicycle is leaned from side to side with the frequency of leaning equal to the frequency of pedalling. Extreme lean angles are +/- 6 degrees. The distance from the hip to the pedal varies approximately sinusoidally with frequency equal to pedalling rate and amplitude somewhat less than crank arm length. The absolute elevation of the hip, however, exhibits two cycles for each crank cycle. Asymmetry in the plot of elevation over a single crank cycle indicates that the pelvis rocks from side to side and that the elevation of the pelvis midpoint changes. Extreme values of the pelvis rocking angle are +/- 12 degrees. Highest pelvis midpoint elevations, however, do not occur at the same crank angles as those angles at which the pelvis rocking is extreme. It appears that the vertical motion of the hips affects pedalling mechanics when cycling in the standing position.
Computer-assisted time-averaged holograms of the motion of the surface of the mammalian tympanic membrane with sound stimuli of 0.4-25 kHz.

PubMed

Rosowski, John J; Cheng, Jeffrey Tao; Ravicz, Michael E; Hulli, Nesim; Hernandez-Montes, Maria; Harrington, Ellery; Furlong, Cosme

2009-07-01

Time-averaged holograms describing the sound-induced motion of the tympanic membrane (TM) in cadaveric preparations from three mammalian species and one live ear were measured using opto-electronic holography. This technique allows rapid measurements of the magnitude of motion of the tympanic membrane surface at frequencies as high as 25 kHz. The holograms measured in response to low and middle-frequency sound stimuli are similar to previously reported time-averaged holograms. However, at higher frequencies (f>4 kHz), our holograms reveal unique TM surface displacement patterns that consist of highly-ordered arrangements of multiple local displacement magnitude maxima, each of which is surrounded by nodal areas of low displacement magnitude. These patterns are similar to modal patterns (two-dimensional standing waves) produced by either the interaction of surface waves traveling in multiple directions or the uniform stimulation of modes of motion that are determined by the structural properties and boundary conditions of the TM. From the ratio of the displacement magnitude peaks to nodal valleys in these apparent surface waves, we estimate a Standing Wave Ratio of at least 4 that is consistent with energy reflection coefficients at the TM boundaries of at least 0.35. It is also consistent with small losses within the uniformly stimulated modal surface waves. We also estimate possible TM surface wave speeds that vary with frequency and species from 20 to 65 m/s, consistent with other estimates in the literature. The presence of standing wave or modal phenomena has previously been intuited from measurements of TM function, but is ignored in some models of tympanic membrane function. Whether these standing waves result either from the interactions of multiple surface waves that travel along the membrane, or by uniformly excited modal displacement patterns of the entire TM surface is still to be determined.

Comparisons: Technical-Tactical and Time-Motion Analysis of Mixed Martial Arts by Outcomes.

PubMed

Miarka, Bianca; Vecchio, Fabrício B D; Camey, Suzi; Amtmann, John A

2016-07-01

Miarka, B, Vecchio, FBD, Camey, S, and Amtmann, JA. Comparisons: technical-tactical and time-motion analysis of mixed martial arts by outcomes. J Strength Cond Res 30(7): 1975-1984, 2016-The aim of this study was to compare time-motion and technical-tactical analysis between paired outcomes and rounds of mixed martial arts (MMA) matches. The sample consisted of 645 rounds of MMA competition paired by outcomes (first round, winners n = 215 and losers n = 215; second round, winners n = 215 and losers n = 215; third round, winners n = 215 and losers n = 215). The time-motion variables were categorized into low-intensity or high-intensity, stand-up or groundwork situations. Stand-up techniques were analyzed by observing total strikes to the head and body, and takedowns. The actions on the ground were analyzed by observing submission activity, including successful choking and joint locking actions, and also positional improvements, including advances to the mount, half guard, and side and back positions. Chi-squared and Wilcoxon tests were conducted with a significance level of p ≤ 0.05. Results showed that winners had higher values for total strikes and submissions in all rounds, and also positional improvements, over losers. The standing combat with low-intensity comparisons presented differences between the rounds first, with a median of 2:33.5 (P25-P75%: 1:20-3:56) minute, second, with 2:37 (1:24-3:59) minute, and third, with 2:07 (1:06-3:39.2) minute. These data suggest a focus on the intermittent demand presented in combat phases with a special attention to the strike and ground technical-tactical skills; strength and conditioning coaches could emphasize the effort pause ratios for both standing and ground combat that mimic the requirements of MMA, especially during the third round.
Miocene tectonics of the Western Alboran domain: from mantle extensional exhumation to westward thrusting

NASA Astrophysics Data System (ADS)

Gueydan, F.; Frasca, G.; Brun, J. P.

2015-12-01

In the frame of the Africa-Europe convergence, the Mediterranean tectonic system presents a complex interaction between subduction rollback and upper-plate deformation during the Tertiary. The western Mediterranean is characterized by the exhumation of the largest subcontinental mantle massif worldwide (the Ronda Peridotite) and a narrow arcuate geometryacross the Gibraltar arc within the Betic-Rif belt (the internal part being called the Alboran domain), where the relationship between slab dynamics and surface tectonics is not well understood. New structural and geochronological data are used to argue for 1/ hyperstrechting of the continental lithosphere allowing extensional mantle exhumation to shallow depths, followed by 2/ lower miocene thrusting. Two Lower Miocene E-W-trending strike-slip corridors played a major role in the deformation pattern of the Alboran Domain, in which E-W dextral strike-slip faults, N60°-trending thrusts and N140°-trending normal faults developed simultaneously during dextral strike-slip simple shear. The inferred continuous westward translation of the Alboran Domain is accommodated by a major E-W-trending lateral ramp (strike-slip) and a N60°-trending frontal thrust. At lithosphere-scale, we interpret the observed deformation pattern as the upper-plate expression of a lateral slab tear and of its westward propagation since Lower Miocene. The crustal emplacement of the Ronda Peridotites occurred at the onset of this westward motion.The Miocene tectonics of the western Alboran is therefore marked by the inversion of a continental rift, triggered by shortening of the upper continental plate and accommodated by E-W dextral strike-slip corridors. During thrusting and westward displacement of the Alboran domain with respect to Iberia, the hot upper plate, which involved the previously exhumed sub-continental mantle, underwent fast cooling.
Lateral ramps in the folded Appalachians and in overthrust belts worldwide; a fundamental element of thrust-belt architecture

USGS Publications Warehouse

Pohn, Howard A.

2000-01-01

Lateral ramps are zones where decollements change stratigraphic level along strike; they differ from frontal ramps, which are zones where decollements change stratigraphic level perpendicular to strike. In the Appalachian Mountains, the surface criteria for recognizing the subsurface presence of lateral ramps include (1) an abrupt change in wavelength or a termination of folds along strike, (2) a conspicuous change in the frequency of mapped faults or disturbed zones (extremely disrupted duplexes) at the surface, (3) long, straight river trends emerging onto the coastal plain or into the Appalachian Plateaus province, (4) major geomorphic discontinuities in the trend of the Blue Ridge province, (5) interruption of Mesozoic basins by cross-strike border faults, and (6) zones of modern and probable ancient seismic activity. Additional features related to lateral ramps include tectonic windows, cross-strike igneous intrusions, areas of giant landslides, and abrupt changes in Paleozoic sedimentation along strike. Proprietary strike-line seismic-reflection profiles cross three of the lateral ramps that were identified by using the surface criteria. The profiles confirm their presence and show their detailed nature in the subsurface. Like frontal ramps, lateral ramps are one of two possible consequences of fold-and-thrust-belt tectonics and are common elements in the Appalachian fold-and-thrust belt. A survey of other thrust belts in the United States and elsewhere strongly suggests that lateral ramps at depth can be identified by their surface effects. Lateral ramps probably are the result of thrust sheet motion caused by continued activation of ancient cratonic fracture systems. Such fractures localized the transform faults along which the continental segments adjusted during episodes of sea-floor spreading.
Development of a bi-directional standing wave linear piezoelectric actuator with four driving feet.

PubMed

Liu, Yingxiang; Shi, Shengjun; Li, Chunhong; Chen, Weishan; Wang, Liang; Liu, Junkao

2018-03-01

A bi-directional standing wave linear piezoelectric ultrasonic actuator with four driving feet is proposed in this work. Two sandwich type transducers operated in longitudinal-bending hybrid modes are set parallelly. The working mode of the transducer is not simple hybrid vibrations of a longitudinal one and a bending one, but a special coupling vibration mode contained both longitudinal and bending components. Two transducers with the same structure and unsymmetrical boundary conditions are set parallelly to accomplish the bi-directional driving: the first transducer can push the runner forward, while the other one produces the backward driving. In the experiments, two voltages with different amplitudes are applied on the two transducers, respectively: the one with higher voltage serves as the actuator, whereas the other one applied with lower voltage is used to reduce the frictional force. The prototype achieves maximum no-load speed and thrust force of 244 mm/s and 9.8 N. This work gives a new idea for the construction of standing wave piezoelectric ultrasonic actuator with bi-directional driving ability. Copyright © 2017 Elsevier B.V. All rights reserved.
Yakataga fold-and-thrust belt: Structural geometry and tectonic implications of a small continental collision zone

NASA Astrophysics Data System (ADS)

Wallace, Wesley K.

Collision of the Yakutat terrane with southern Alaska created a collisional fold-and-thrust belt along the Pacific-North America plate boundary. This southerner fold-and-thrust belt formed within continental sedimentary rocks but with the seaward vergence and tectonic position typical of an accretionary wedge. Northward exposure of progressively older rocks reflects that the fold-and-thrust belt forms a southward-tapered orogenic wedge that increases northward in structural relief and depth of erosion. Narrow, sharp anticlines separate wider, flat-bottomed synclines. Relatively steep thrust faults commonly cut the forelimbs of anticlines. Fold shortening and fault displacement both generally increase northward, whereas fault dip generally decreases northward. The coal-bearing lower part of the sedimentary section serves as a detachment for both folds and thrust faults. The folded and faulted sedimentary section defines a regional south dip of about 8°. The structural relief combined with the low magnitude of shortening of the sedimentary section suggest that the underlying basement is structurally thickened. I propose a new interpretation in which this thickening was accommodated by a passive-roof duplex with basement horses that are separated from the overlying folded and thrust-faulted sedimentary cover by a roof thrust with a backthrust sense of motion. Basement horses are ˜7 km thick, based on the thickness between the inferred roof thrust and the top of the basement in offshore seismic reflection data. This thickness is consistent with the depth of the zone of seismicity onshore. The inferred zone of detachment and imbrication of basement corresponds with the area of surface exposure of the fold-and-thrust belt within the Yakutat terrane and with the Wrangell subduction zone and arc farther landward. By contrast, to the west, the crust of the Yakutat terrane has been carried down a subduction zone that extends far landward with a gentle dip, corresponding with a gap in arc magmatism, anomalous topography, and the rupture zone of the 1964 great southern Alaska earthquake. I suggest that, to the east, detachment and imbrication of basement combined with coupling in the fold-and-thrust belt allowed the delaminated dense mantle lithosphere to subduct with a steeper dip than to the west, where buoyant Yakutat terrane crust remains attached to the subducted lithosphere. According to this interpretation, the Wrangell subduction zone is lithosphere of the Yakutat terrane, not Pacific Ocean lithosphere subducted beneath the Yakutat terrane. The Pacific-North America plate boundary would be within the northern deformed part of the Yakutat terrane, not along the boundary between the undeformed southern part of the Yakutat terrane and oceanic crust of the Pacific Ocean. The plate boundary is an evolving zone of distributed deformation in which most of the convergent component has been accommodated within the fold-and-thrust belt south of the northern boundary of the Yakutat terrane, the Chugach-St. Elias thrust fault, and most of the right-lateral component likely has been accommodated on the Bagley Icefield fault just to the north.
Slip Model of the 2015 Mw 7.8 Gorkha (Nepal) Earthquake from Inversions of ALOS-2 and GPS Data

NASA Astrophysics Data System (ADS)

Wang, K.; Fialko, Y. A.

2015-12-01

We use surface deformation measurements including Interferometric Synthetic Aperture Radar (InSAR) data acquired by the ALOS-2 mission of the Japanese Aerospace Exploration Agency (JAXA) and Global Positioning System (GPS) data to invert for the fault geometry and coseismic slip distribution of the 2015 Mw 7.8 Gorkha earthquake in Nepal. Assuming that the ruptured fault connects to the surface trace of the of Main Frontal Thrust fault (MFT) between 84.34E and 86.19E, the best-fitting model suggests a dip angle of 7 degrees. The moment calculated from the slip model is 6.17*1020 Nm, corresponding to the moment magnitude of 7.79. The rupture of the 2015 Gorkha earthquake was dominated by thrust motion that was primarily concentrated in a 150-km long zone 50 to 100 km northward from the surface trace of the Main Frontal Thrust (MFT), with maximum slip of ~6 m at a depth of ~ 8 km. Data thus indicate that the 2015 Gorkha earthquake ruptured a deep part of the seismogenic zone, in contrast to the 1934 Bihar-Nepal earthquake, which had ruptured a shallow part of the adjacent fault segment to the East.
Tertiary thrust systems and fluid flow beneath the Beaufort coastal plain (1002 area), Arctic National Wildlife Refuge, Alaska, U.S.A.

USGS Publications Warehouse

Potter, Christopher J.; Grow, John A.; Perry, William J.; Moore, Thomas E.; O'Sullivan, Paul B.; Phillips, Jeffrey D.; Saltus, Richard W.

2004-01-01

In the eastern part of the 1002 area, a northward-younging pattern of thin-skinned deformation is apparent. Converging patterns of Paleocene reflectors on the north flank of the Sabbath syncline indicate that the Aichilik high and the Sabbath syncline formed as a passive-roof duplex and piggyback basin, respectively, just behind the Paleocene deformation front. During the Eocene and possibly the Oligocene, thin-skinned thrusting advanced northward over the present location of the Niguanak high. A passive-roof duplex occupied the frontal part of this system. The Kingak and Hue shales exposed above the Niguanak high were transported into their present structural position during the Eocene to Oligocene motion on the long thrust ramps above the present south flank of the Niguanak high. Broad, basement-cored subsurface domes (Niguanak high and Aurora dome) formed near the deformation front in the Oligocene, deforming the overlying thin-skinned structures and feeding a new increment of displacement into thin-skinned structures directly to the north. Deformation continued through the Miocene above a detachment in the basement. Offshore seismicity and Holocene shortening documented by previous workers may indicate that contractional deformation continues to the present day.
Preliminary design study of a lateral-directional control system using thrust vectoring

NASA Technical Reports Server (NTRS)

Lallman, F. J.

1985-01-01

A preliminary design of a lateral-directional control system for a fighter airplane capable of controlled operation at extreme angles of attack is developed. The subject airplane is representative of a modern twin-engine high-performance jet fighter, is equipped with ailerons, rudder, and independent horizontal-tail surfaces. Idealized bidirectional thrust-vectoring engine nozzles are appended to the mathematic model of the airplane to provide additional control moments. Optimal schedules for lateral and directional pseudo control variables are calculated. Use of pseudo controls results in coordinated operation of the aerodynamic and thrust-vectoring controls with minimum coupling between the lateral and directional airplane dynamics. Linear quadratic regulator designs are used to specify a preliminary flight control system to improve the stability and response characteristics of the airplane. Simulated responses to step pilot control inputs are stable and well behaved. For lateral stick deflections, peak stability axis roll rates are between 1.25 and 1.60 rad/sec over an angle-of-attack range of 10 deg to 70 deg. For rudder pedal deflections, the roll rates accompanying the sideslip responses can be arrested by small lateral stick motions.
Earthquake swarm of Himachal Pradesh in northwest Himalaya and its seismotectonic implications

NASA Astrophysics Data System (ADS)

Singh, Rakesh; Prasath, R. Arun; Paul, Ajay; Kumar, Naresh

2018-02-01

On the 27th of August 2016, a seismic swarm activity consisting of 58 earthquakes (1.5 ≤ ML ≤ 4.4), which occurred in Rampur area of the Kullu-Rampur Tectonic window of Himachal Pradesh in Northwest Himalaya. The epicenters of these events are located at the northern front of the Berinag Thrust in its hanging wall. To better understand the seismotectonics of this region, we analyzed the spectral source parameters and source mechanism of this swam activity. Spectral analysis shows the low stress drop values (from 0.05 to 28.9 bars), suggesting that the upper crust has low strength to withstand accumulated strain energy in this region. The Moment Tensor solutions of 12 earthquakes (≥2.7ML) obtained by waveform inversion yield the shallow centroid depths between 5 and 10 km. All these events are of dominantly thrust fault mechanism having an average dip angle of ∼30°. The P-axes and the maximum horizontal compressive stresses are NE-SW oriented; the relative motion of the Indian Plate. The present study reveals that the swarm activity in the Himachal region of NW Himalaya is related to the out-of-sequence thrusting or the Lesser Himalayan Duplex system.
Pursuit-evasion games with information uncertainties for elusive orbital maneuver and space object tracking

NASA Astrophysics Data System (ADS)

Shen, Dan; Jia, Bin; Chen, Genshe; Blasch, Erik; Pham, Khanh

2015-05-01

This paper develops and evaluates a pursuit-evasion (PE) game approach for elusive orbital maneuver and space object tracking. Unlike the PE games in the literature, where the assumption is that either both players have perfect knowledge of the opponents' positions or use primitive sensing models, the proposed PE approach solves the realistic space situation awareness (SSA) problem with imperfect information, where the evaders will exploit the pursuers' sensing and tracking models to confuse their opponents by maneuvering their orbits to increase the uncertainties, which the pursuers perform orbital maneuvers to minimize. In the game setup, each game player P (pursuer) and E (evader) has its own motion equations with a small continuous low-thrust. The magnitude of the low thrust is fixed and the direction can be controlled by the associated game player. The entropic uncertainty is used to generate the cost functions of game players. The Nash or mixed Nash equilibrium is composed of the directional controls of low-thrusts. Numerical simulations are emulated to demonstrate the performance. Simplified perturbations models (SGP4/SDP4) are exploited to calculate the ground truth of the satellite states (position and speed).
Regeneratively Cooled Liquid Oxygen/Methane Technology Development

NASA Technical Reports Server (NTRS)

Robinson, Joel W.; Greene, Christopher B.; Stout, Jeffrey

2012-01-01

The National Aeronautics & Space Administration (NASA) has identified Liquid Oxygen (LOX)/Liquid Methane (LCH4) as a potential propellant combination for future space vehicles based upon exploration studies. The technology is estimated to have higher performance and lower overall systems mass compared to existing hypergolic propulsion systems. NASA-Marshall Space Flight Center (MSFC) in concert with industry partner Pratt & Whitney Rocketdyne (PWR) utilized a Space Act Agreement to test an oxygen/methane engine system in the Summer of 2010. PWR provided a 5,500 lbf (24,465 N) LOX/LCH4 regenerative cycle engine to demonstrate advanced thrust chamber assembly hardware and to evaluate the performance characteristics of the system. The chamber designs offered alternatives to traditional regenerative engine designs with improvements in cost and/or performance. MSFC provided the test stand, consumables and test personnel. The hot fire testing explored the effective cooling of one of the thrust chamber designs along with determining the combustion efficiency with variations of pressure and mixture ratio. The paper will summarize the status of these efforts.
Overview of 10 inch Diameter HTPB Hybrid Motor Testing with Liquid Oxygen at Stennis Space Center

NASA Technical Reports Server (NTRS)

Knowles, Timothy E.; Kearney, Darren; Roberts, Ryan

2005-01-01

To further explore the operation of hybrid rocket motors and to demonstrate the performance characteristics of the motor design Lockheed Martin funded research on a series of 10 inch diameter hybrid motors that produce less than 10 klbf sea level thrust. This test series was given the name "Hybrid Technology Test Program." These motors were fired in the existing test stand at the SSC E-3 complex Cell 1. The fuel and oxidizer for these 10 inch diameter motors are HTPB and LO2, respectively. The original goal of the testing was to verify that the predicted performance matched the actual performance of these 10 inch motors (ref. figure 1) and then confirm that the motors performed acceptably. For this element of testing horizontally fired hybrid motors will be tested using LO2 supplied from the existing facility 100 gallon LO2 tank that is pressurized with facility GN2. The thrust produced by the motor will be measured by a Lockheed Martin supplied load cell.
Pitching motion control of a butterfly-like 3D flapping wing-body model

NASA Astrophysics Data System (ADS)

Suzuki, Kosuke; Minami, Keisuke; Inamuro, Takaji

2014-11-01

Free flights and a pitching motion control of a butterfly-like flapping wing-body model are numerically investigated by using an immersed boundary-lattice Boltzmann method. The model flaps downward for generating the lift force and backward for generating the thrust force. Although the model can go upward against the gravity by the generated lift force, the model generates the nose-up torque, consequently gets off-balance. In this study, we discuss a way to control the pitching motion by flexing the body of the wing-body model like an actual butterfly. The body of the model is composed of two straight rigid rod connected by a rotary actuator. It is found that the pitching angle is suppressed in the range of +/-5° by using the proportional-plus-integral-plus-derivative (PID) control for the input torque of the rotary actuator.
Measurement of horizontal motions in Alaska using very long baseline interferometry

NASA Technical Reports Server (NTRS)

Ma, C.; Sauber, J. M.; Clark, T. A.; Ryan, J. W.; Bell, L. J.; Gordon, D.; Himwich, W. E.

1990-01-01

Results are presented on an analysis of VLBI measurements performed between 1984 and 1990 by means of a network of 53 sites in Alaska, the Yukon Territory, and the conterminous United States to determine the extent of horizontal motions in Alaska. Results are presented in two ways, one showing the evolution of individual baselines and the other yielding site velocities; both approaches use VLBI data from other permanent stations in order to define a global reference frame. It was found that VLBI sites within the Alaska-Aleutian subduction boundary zone (Yakataga, Kodiak, and Sand Point) had higher instantaneous velocities relative to eastern North America than the interior sites of Alaska. The results of Yakataga data modeling suggests that the observed motion is the result of elastic straining of the overriding plate due to a locked main thrust zone with a component of oblique slip.
The effect of different unstable footwear constructions on centre of pressure motion during standing.

PubMed

Plom, W; Strike, S C; Taylor, M J D

2014-06-01

The aim of this study was to test the effect different unstable footwear constructions have on centre of pressure motion when standing. Sixteen young female volunteers were tested in five conditions, three unstable footwear (Reebok Easy-Tone, FitFlop and Skechers Shape-Ups), a standard shoe and barefoot in a randomised order. Double and single leg balance on a force plate was assessed via centre of pressure excursions and displacements in each condition. For double leg and single leg standing centre of pressure excursions in the anterior-posterior direction were significantly increased wearing Skechers Shape-Ups compared to barefoot and the standard shoe. For the Reebok Easy Tone during single leg standing excursions in the anterior-posterior direction were significantly greater compared to the barefoot condition. Cumulative displacement of the centre of pressure in medial-lateral direction increased significantly during single leg standing when wearing Skechers Shape-Ups compared to barefoot and standard shoe as well as for Reebok Easy Tone vs. barefoot. It would appear from these quiet standing results that the manner of the construction of instability shoes effects the CoP movement which is associated with induced instability. Greater CoP excursion occurred in the A-P direction while the cumulative displacements were greater in the M-L direction for those shoes with the rounded sole and soft foam and those with airpods. The shoe construction with altered density foam did not induce any change in the CoP movement, during quite standing, which tends to suggest that it is not effective at inducing balance. Not all instability shoes are effective in altering the overall instability of the wearer. Copyright © 2014 Elsevier B.V. All rights reserved.
Method and apparatus for adapting steady flow with cyclic thermodynamics

DOEpatents

Swift, Gregory W.; Reid, Robert S.; Ward, William C.

2000-01-01

Energy transfer apparatus has a resonator for supporting standing acoustic waves at a selected frequency with a steady flow process fluid thermodynamic medium and a solid medium having heat capacity. The fluid medium and the solid medium are disposed within the resonator for thermal contact therebetween and for relative motion therebetween. The relative motion is produced by a first means for producing a steady velocity component and second means for producing an oscillating velocity component at the selected frequency and concomitant wavelength of the standing acoustic wave. The oscillating velocity and associated oscillating pressure component provide energy transfer between the steady flow process fluid and the solid medium as the steady flow process fluid moves through the resonator.
Variable exhumation rates and variable displacement rates: Documenting recent slowing of Himalayan shortening in western Bhutan

USGS Publications Warehouse

McQuarrie, Nadine; Tobgay, Tobgay; Long, Sean P.; Reiners, Peter W.; Cosca, Michael A.

2014-01-01

We link exhumational variability in space and time to the evolving geometry of the Himalayan fold–thrust belt in western Bhutan. By combining new and published geochronologic and thermochronologic data we document the burial age, peak temperatures and complete cooling history from 20 Ma to the present over an across-strike distance of ∼125 km. These integrated cooling curves highlight windows of fast exhumation that vary spatially and temporally. We propose that pulses of fast exhumation are a result of structures that facilitate the vertical motion of material, illustrated in sequentially-restored cross sections. Due to a range of permissible geometries at depth, we explore and evaluate the impact of geometry on kinematics and rates of deformation. The linked cooling history and cross sections provide estimates of both magnitude and timing of thrust sheet displacement and highlight temporal variability in potential shortening rates. Structural and chronologic data illustrate a general north to south progression of Himalayan deformation, with emplacement of the Main Central thrust (MCT), Paro thrust and Shumar thrust by 12 to no later than 9 Ma. Two different geometries and kinematic scenarios for the Lesser Himalayan duplex are proposed. A north to south propagating duplex system requires that the southern portion of that system, south of the MCT, deformed and cooled by 9 Ma, leaving only the southernmost thrust sheets, including the Main Boundary and Main Frontal thrusts, to deform between 9 and 0 Ma. This limited post 9 Ma shortening would necessitate a marked slowdown in convergence accommodated on the Main Himalayan thrust. A two-tiered duplex system, which allows for the Paro window duplex and the southern Baxa duplex to form simultaneously, permits duplex formation and accompanying exhumation until 6 Ma. Limited cooling from ∼200 °C to the surface post 6 Ma suggests either a decrease in shortening rates from 6 to 0 Ma or that duplex formation and exhumation are temporally decoupled. Our combined cooling curves highlight that the youngest cooling ages may not mark the fastest thrusting rates or the window of fastest exhumation. Instead, temporal variations in exhumation are best viewed through identifying transients in exhumation rate. We suggest that the strongest control on exhumation magnitude and variability is fold–thrust belt geometry, particularly the locations and magnitudes of footwall ramps, which can change over 10ʼs of km distance. Balanced cross sections predict the location and magnitude of these ramps and how they vary in space and time, providing an untapped potential for testing permissible cross-section geometries and kinematics against measured cooling histories.
Interseismic Strain Accumulation Across Metropolitan Los Angeles: Puente Hills Thrust

NASA Astrophysics Data System (ADS)

Argus, D.; Liu, Z.; Heflin, M. B.; Moore, A. W.; Owen, S. E.; Lundgren, P.; Drake, V. G.; Rodriguez, I. I.

2012-12-01

Twelve years of observation of the Southern California Integrated GPS Network (SCIGN) are tightly constraining the distribution of shortening across metropolitan Los Angeles, providing information on strain accumulation across blind thrust faults. Synthetic Aperture Radar Interferometry (InSAR) and water well records are allowing the effects of water and oil management to be distinguished. The Mojave segment of the San Andreas fault is at a 25° angle to Pacific-North America plate motion. GPS shows that NNE-SSW shortening due to this big restraining bend is fastest not immediately south of the San Andreas fault across the San Gabriel mountains, but rather 50 km south of the fault in northern metropolitan Los Angeles. The GPS results we quote next are for a NNE profile through downtown Los Angeles. Just 2 mm/yr of shortening is being taken up across the San Gabriel mountains, 40 km wide (0.05 micro strain/yr); 4 mm/yr of shortening is being taken up between the Sierra Madre fault, at the southern front of the San Gabriel mountains, and South Central Los Angeles, also 40 km wide (0.10 micro strain/yr). We find shortening to be more evenly distributed across metropolitan Los Angeles than we found before [Argus et al. 2005], though within the 95% confidence limits. An elastic models of interseismic strain accumulation is fit to the GPS observations using the Back Slip model of Savage [1983]. Rheology differences between crystalline basement and sedimentary basin rocks are incorporated using the EDGRN/EDCMP algorithm of Wang et al. [2003]. We attempt to place the Back Slip model into the context of the Elastic Subducting Plate Model of Kanda and Simons [2010]. We find, along the NNE profile through downtown, that: (1) The deep Sierra Madre Thrust cannot be slipping faster than 2 mm/yr, and (2) The Puente Hills Thrust and nearby thrust faults (such as the upper Elysian Park Thrust) are slipping at 9 ±2 mm/yr beneath a locking depth of 12 ±5 km (95% confidence limits). Incorporating sedimentary basin rock either reduces the slip rate by 10 per cent or increases the locking rate by 20 per cent. The 9 mm/yr rate for the Puente Hills Thrust and nearby faults exceeds the cumulative 3-5 mm/yr rate estimated using paleoseismology along the Puente Hills Thrust (1.2-1.6 mm/yr, Dolan et al. 2003), upper Elysian Park Thrust (0.6-2.2 mm/yr, Oskin et al. 2000), and western Compton Thrust (1.2 mm/yr, Leon et al. 2009], though all the paleoseismic estimates are minimums. We infer that M 7 earthquakes in northern metropolitan Los Angeles may occur more frequently that previously thought.
IPMC-driven thrust generation: a new conceptual design (Conference Presentation)

NASA Astrophysics Data System (ADS)

Olsen, Zakai; Kim, Kwang Jin

2017-04-01

Ionic Polymer-Metal Composites (IPMC) are highly functional actuators that find many uses in the field of soft robotics due to their low actuation voltage and ability to operate in aquatic environments. The actuation of an IPMC relies on the swelling of the negatively charged side when a potential is applied, due to the free-moving cations and water molecules migrating to that half. While this bending type actuation can be utilized to perform many tasks, it is ill suited for the primary propulsion mechanism in certain soft robotic applications. Here, a new conceptual design is presented which utilizes the bending of IPMC materials to achieve complex actuation motion in an attempt to generate a non-zero net thrust for propulsion of soft robots. The design capitalizes on advances in the manufacturing processes of electroactive polymer materials, which now allow for more complex shapes and thus new and unique modes of actuation. By utilizing the consistent bending deformation of IPMC actuators, in conjunction with carefully considered geometry, an IPMC driven body may serve as a primary mode of propulsion through a positive net thrust generation. This work consists of the initial feasibility study, concept testing, and optimization for such an actuator through computer modeling and simulation. COMSOL will be used for the finite element analysis to design the most efficient and optimized design for a positive net thrust generation. Such an IPMC design may find a great deal of applications, and the potential of future integration into other soft robotic systems is considered.
Solid Rocket Booster Separation

NASA Technical Reports Server (NTRS)

1998-01-01

This Quick Time movie shows the Space Shuttle Solid Rocket Booster (SRB) separation from the external tank (ET). After separation, the boosters fall to the ocean from which they are retrieved and refurbished for reuse. The Shuttle's SRB's and solid rocket motors (SRM's) are the largest ever built and the first designed for refurbishment and reuse. Standing nearly 150-feet high, the twin boosters provide the majority of thrust for the first two minutes of flight, about 5.8 million pounds. That is equivalent to 44 million horsepower, or the combined power of 400,000 subcompact cars.

KSC-04pd0949

NASA Image and Video Library

2004-04-21

KENNEDY SPACE CENTER, FLA. - In the Orbiter Processing Facility, workers stand by as the left-hand Orbital Maneuvering System (OMS) pod is maneuvered toward the engine interfaces on the orbiter Discovery for installation. The Orbital Maneuvering System provides the thrust for orbit insertion, orbit circularization, orbit transfer, rendezvous, deorbit, abort to orbit and abort once around. It can provide up to 1,000 pounds of propellant to the aft reaction control system. Each pod contains one OMS engine and the hardware needed to pressurize, store and distribute the propellants to perform the velocity maneuvers.
Saturn V Second Stage (S-II) Ready for Static Test

NASA Technical Reports Server (NTRS)

1965-01-01

Two workers are dwarfed by the five J-2 engines of the Saturn V second stage (S-II) as they make final inspections prior to a static test firing by North American Space Division. These five hydrogen -fueled engines produced one million pounds of thrust, and placed the Apollo spacecraft into earth orbit before departing for the moon. The towering 363-foot Saturn V was a multi-stage, multi-engine launch vehicle standing taller than the Statue of Liberty. Altogether, the Saturn V engines produced as much power as 85 Hoover Dams.
Saturn Apollo Program

NASA Image and Video Library

1965-04-01

S-IB-1, the first flight version of the Saturn IB launch vehicle's first stage (S-IB stage), undergoes a full-duration static firing in Saturn IB static test stand at the Marshall Space Flight Center (MSFC) on April 13, 1965. Developed by the MSFC and built by the Chrysler Corporation at the Michoud Assembly Facility (MAF) in New Orleans, Louisiana, the 90,000-pound booster utilized eight H-1 engines to produce a combined thrust of 1,600,000 pounds. Between April 1965 and July 1968, MSFC performed thirty-two static tests on twelve different S-IB stages.
Influence of standing or seated pelvis on dummy responses in rear impacts.

PubMed

Viano, David C; Parenteau, Chantal S; Burnett, Roger

2012-03-01

There is a question whether the standing or seated pelvis should be used in Hybrid III dummy evaluations of seats and belt restraint systems in severe rear impacts. This study compares the standing and seated Hybrid III pelvis in matched rear sled tests. Sixteen sled tests were found at 10, 16 and 24 km/h rear delta V in Ford's archives where matched tests were run with the standing and seated pelvis in a belted Hybrid III dummy. Two new tests were conducted at 40 km/h rear delta V to extend the severity range. The head, chest and pelvis were instrumented with triaxial accelerometers and the upper and lower neck, thoracic spine and lumbar spine had transducers measuring triaxial loads and moments. Belt Loads were measured. High-speed video recorded different views of the dummy motion. Dummy kinematics and biomechanical responses were compared for all of the data with the two different Hybrid III pelvic designs. In the 40 km/h sled tests, the dummy motion and excursion were essentially similar with the standing and seated pelvis. The similarities included the lap belt interaction with the pelvis and the leg movement upward flexing the hip joint. Overall, similar biomechanic and kinematic responses were found, including the pelvic acceleration, spinal forces and moments. For the lower speed tests at 10, 16 and 24 km/h, the motion sequence was also similar with the two different pelvises, including the upward movement of the legs as the seat was loaded and rebound kinematics. The biomechanical responses were similar. The seated pelvis involves only a small portion of the upper leg molded into the vinyl skin of the pelvis and does not limit leg rotation at the hip joint. Furthermore, lap belt loads were minimal during the rearward movement of the dummy. The matched testing showed no significant difference in occupant kinematics or biomechanical responses between the standing and seated pelvis in rear sled tests. The Hybrid III dummy with the seated pelvis is suitable for FMVSS 301 and other testing of seats and belt restraint systems in severe rear impacts. Copyright © 2011 Elsevier Ltd. All rights reserved.
The balance and harmony of control power for a combat aircraft in tactical maneuvering

NASA Technical Reports Server (NTRS)

Bocvarov, Spiro; Cliff, Eugene M.; Lutze, Frederick H.

1992-01-01

An analysis is presented for a family of regular extremal attitude-maneuvers for the High Angle-of-Attack Research Vehicle that has thrust-vectoring capability. Different levels of dynamic coupling are identified in the combat aircraft attitude model, and the characteristic extremal-family motion is explained. It is shown why the extremal-family trajectories develop small sideslip-angles, a highly desirable feature from a practical viewpoint.
Coulomb Thrusting Application Study

DTIC Science & Technology

2006-01-20

Acceleration Magnitudes To study the relative motion of spacecraft in nearly circular orbits, the Clohessy - Wiltshire - Hill equations are commonly...Modeling The Clohessy - Wiltshire -Hill’s equations12–14 for one of the spacecraft in the 2-craft Coulomb tether formation is given by ẍ1 − 2nẏ1...equa- tion was obtained using the Clohessy - Wiltshire - Hill equations, while the linearized differential equations of ψ and θ were derived from the full
Leg Injuries and Disorders

MedlinePlus

... are important for motion and standing. Playing sports, running, falling, or having an accident can damage your legs. Common leg injuries include sprains and strains, joint dislocations, and fractures. ...
Strain Variation in Accretionary Prisms Across Space and Time: Insights from the Makran Subduction Zone

NASA Astrophysics Data System (ADS)

Penney, C.; Tavakoli, F.; Saadat, A.; Nankali, H. R.; Sedighi, M.; Khorrami, F.; Sobouti, F.; Rafi, Z.; Copley, A.; Jackson, J. A.; Priestley, K. F.

2017-12-01

The Makran is one of the world's least-studied subduction zones. In particular, little is known about the accumulation and accommodation of strain in the onshore part of the subduction zone, which parallels the coasts of southern Iran and Pakistan. The deformation of the Makran accretionary prism results from both its subduction zone setting and N-S right-lateral shear between central Iran and Afghanistan. North of the Makran, this shear is accommodated by a series of right-lateral faults which offset the rocks of the Sistan Suture Zone, an abandoned accretionary prism. However, these right-lateral faults are not observed south of 27°N, and no major N-S faults cut the E-W trending structures of the Makran. How this right-lateral motion is accommodated at the southern end of the Sistan Suture Zone is a long-standing tectonic question. By combining results from geomorphology, GPS, seismology and modelling we conclude that right-lateral motion is transferred across the depression north of the accretionary prism to the region of right-lateral shear at the western end of the accretionary prism. This requires the Jaz Murian depression to be bounded by normal faults, consistent with the basin geomorphology. However, GPS data show compression across the margins of the basin, and no shallow normal-faulting earthquakes have been observed in the region. We therefore suggest that the behaviour of these faults may be time-dependent and controlled by the megathrust seismic cycle, as has been suggested elsewhere (e.g. Chile). Recent strike-slip earthquakes, including the 2013 Balochistan earthquake, have clustered at the prism's lateral edges, showing the importance of spatial, as well as temporal, variations in strain. These earthquakes have reactivated thrust faults in the Makran accretionary prism, showing that the style of strain within accretionary prisms can vary on multiple timescales and allowing us to calculate the coefficient of friction on the underlying megathrust.
Around Marshall

NASA Image and Video Library

1961-08-14

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photo shows the construction progress of the test stand as of August 14, 1961.
Around Marshall

NASA Image and Video Library

1961-08-18

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photo shows the construction progress of the test stand as of August 18, 1961.
Around Marshall

NASA Image and Video Library

1963-01-14

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photo, depicts the progress of the stand as of January 14, 1963, with its four towers prominently rising.
Around Marshall

NASA Image and Video Library

1963-04-17

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photograph taken April 17, 1963, gives a look at the four tower legs of the S-IC test stand at their completed height.
Around Marshall

NASA Image and Video Library

1961-07-21

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In this photo, taken July 21, 1961, a worker can be seen inside the test stand work area with a jack hammer.
Around Marshall

NASA Image and Video Library

1963-11-20

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photo shows the progress of the S-IC test stand as of November 20, 1963.
Around Marshall

NASA Image and Video Library

1963-06-24

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In this photo, taken June 24, 1963, the four tower legs of the test stand can be seen at their maximum height.
Around Marshall

NASA Image and Video Library

1961-07-31

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. In this photo, taken July 31, 1961, work is continued in the clearing of the test stand site.
Around Marshall

NASA Image and Video Library

1963-02-25

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photograph taken February 25, 1963, gives a close up look at two of the ever-growing four towers of the S-IC Test Stand.
Around Marshall

NASA Image and Video Library

1961-08-11

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photo shows the construction progress of the test stand as of August 11, 1961.
Around Marshall

NASA Image and Video Library

1963-05-07

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photograph, taken from ground level on May 7, 1963, gives a close look at one of the four towers legs of the S-IC test stand nearing its completed height.
Around Marshall

NASA Image and Video Library

1963-05-07

At its founding, the Marshall Space Flight Center (MSFC) inherited the Army’s Jupiter and Redstone test stands, but much larger facilities were needed for the giant stages of the Saturn V. From 1960 to 1964, the existing stands were remodeled and a sizable new test area was developed. The new comprehensive test complex for propulsion and structural dynamics was unique within the nation and the free world, and they remain so today because they were constructed with foresight to meet the future as well as on going needs. Construction of the S-IC Static test stand complex began in 1961 in the west test area of MSFC, and was completed in 1964. The S-IC static test stand was designed to develop and test the 138-ft long and 33-ft diameter Saturn V S-IC first stage, or booster stage, weighing in at 280,000 pounds. Required to hold down the brute force of a 7,500,000-pound thrust produced by 5 F-1 engines, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and 12,000,000 pounds of cement, planted down to bedrock 40 feet below ground level. The foundation walls, constructed with concrete and steel, are 4 feet thick. The base structure consists of four towers with 40-foot-thick walls extending upward 144 feet above ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the upright position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. This photograph, taken May 7, 1963, gives a close look at the four concrete tower legs of the S-IC test stand at their completed height.

Some links on this page may take you to non-federal websites. Their policies may differ from this site.