Thrust Breakdown Characteristics of Conventional Propellers

DTIC Science & Technology

2007-09-01

extends beyond the trailing edge of the blade . These sheets violently collapse as the blade moves out of the wake deficit produced by the hull. This...thrust breakdown, vibration, noise , erosion and blade damage. Propellers operating with enough cavitation to cause thrust breakdown can experience...7 Figure 5. Sensitivity of thrust reduction to harmonic content in wake (Prop 5491) .................. 8 Figure 6. Comparison of

The standardized functional support sectional for the Small Astronomy Satellite (SAS)

NASA Technical Reports Server (NTRS)

Townsend, M. R.

1974-01-01

The standardized functional support section for the improved Small Astronomy Satellite (SAS) spacecraft, which can be used virtually without change for a wide variety of experimental packages and missions, is described. This functional support section makes the spacecraft remarkably flexible for a small satellite. Able to point its thrust axis to any direction in space, it can also spin or slow its outer body rotation to zero for star- or earth-locked pointing of side-viewing experiments. It features a reprogrammable telemetry system, a delayed command system, and an improved control system. Experiments can be built independently and attached to the SAS spacecraft just prior to final acceptance testing and launch. The spacecraft subsystems are described in detail. Included are a summary of the spacecraft characteristics, special design considerations, project reliability requirements, and environmental test conditions. It is intended that this new functional support section afford virtual off-the-shelf availability of the SAS spacecraft to independently built experiments, thus providing quick response time and minimum cost in meeting a wide variety of experimenter needs.

The challenges of numerically simulating analogue brittle thrust wedges

NASA Astrophysics Data System (ADS)

Buiter, Susanne; Ellis, Susan

2017-04-01

Fold-and-thrust belts and accretionary wedges form when sedimentary and crustal rocks are compressed into thrusts and folds in the foreland of an orogen or at a subduction trench. For over a century, analogue models have been used to investigate the deformation characteristics of such brittle wedges. These models predict wedge shapes that agree with analytical critical taper theory and internal deformation structures that well resemble natural observations. In a series of comparison experiments for thrust wedges, called the GeoMod2004 (1,2) and GeoMod2008 (3,4) experiments, it was shown that different numerical solution methods successfully reproduce sandbox thrust wedges. However, the GeoMod2008 benchmark also pointed to the difficulties of representing frictional boundary conditions and sharp velocity discontinuities with continuum numerical methods, in addition to the well-known challenges of numerical plasticity. Here we show how details in the numerical implementation of boundary conditions can substantially impact numerical wedge deformation. We consider experiment 1 of the GeoMod2008 brittle thrust wedge benchmarks. This experiment examines a triangular thrust wedge in the stable field of critical taper theory that should remain stable, that is, without internal deformation, when sliding over a basal frictional surface. The thrust wedge is translated by lateral displacement of a rigid mobile wall. The corner between the mobile wall and the subsurface is a velocity discontinuity. Using our finite-element code SULEC, we show how different approaches to implementing boundary friction (boundary layer or contact elements) and the velocity discontinuity (various smoothing schemes) can cause the wedge to indeed translate in a stable manner or to undergo internal deformation (which is a fail). We recommend that numerical studies of sandbox setups not only report the details of their implementation of boundary conditions, but also document the modelling attempts that failed. References 1. Buiter and the GeoMod2004 Team, 2006. The numerical sandbox: comparison of model results for a shortening and an extension experiment. Geol. Soc. Lond. Spec. Publ. 253, 29-64 2. Schreurs and the GeoMod2004 Team, 2006. Analogue benchmarks of shortening and extension experiments. Geol. Soc. Lond. Spec. Publ. 253, 1-27 3. Buiter, Schreurs and the GeoMod2008 Team, 2016. Benchmarking numerical models of brittle thrust wedges, J. Struct. Geol. 92, 140-177 4. Schreurs, Buiter and the GeoMod2008 Team, 2016. Benchmarking analogue models of brittle thrust wedges, J. Struct. Geol. 92, 116-13

In-water gas combustion for thrust production

NASA Astrophysics Data System (ADS)

Teslenko, V. S.; Drozhzhin, A. P.; Medvedev, R. N.

2017-07-01

The paper presents the results of experimental study for hydrodynamic processes occurring during combustion of a stoichiometric mixture propane-oxygen in combustion chambers with different configurations and submerged into water. The pulses of force acting upon a thrust wall were measured for different geometries: cylindrical, conic, hemispherical, including the case of gas combustion near a flat thrust wall. After a single charge of stoichiometric mixture propane-oxygen is burnt near the thrust wall, the process of cyclic generation of force pulses develops. The first pulse is generated due to pressure growth during gas combustion, and the following pulses are the result of hydrodynamic pulsations of the gaseous cavity. Experiments demonstrated that efficient generation of thrust occurs if all bubble pulsations are used during combustion of a single gas combustion. In the series of experiments, the specific impulse on the thrust wall was in the range 104-105 s (105-106 m/s) with account for positive and negative components of impulse.

An Investigation of Ionic Wind Propulsion

NASA Technical Reports Server (NTRS)

Wilson, Jack; Perkins, Hugh D.; Thompson, William K.

2009-01-01

A corona discharge device generates an ionic wind and thrust, when a high voltage corona discharge is struck between sharply pointed electrodes and larger radius ground electrodes. The objective of this study was to examine whether this thrust could be scaled to values of interest for aircraft propulsion. An initial experiment showed that the thrust observed did equal the thrust of the ionic wind. Different types of high voltage electrodes were tried, including wires, knife-edges, and arrays of pins. A pin array was found to be optimum. Parametric experiments, and theory, showed that the thrust per unit power could be raised from early values of 5 N/kW to values approaching 50 N/kW, but only by lowering the thrust produced, and raising the voltage applied. In addition to using DC voltage, pulsed excitation, with and without a DC bias, was examined. The results were inconclusive as to whether this was advantageous. It was concluded that the use of a corona discharge for aircraft propulsion did not seem very practical.

Solar Sails: Sneaking up on Interstellar Travel

NASA Astrophysics Data System (ADS)

Johnson, L.

Throughout the world, government agencies, universities and private companies are developing solar sail propulsion systems to more efficiently explore the solar system and to enable science and exploration missions that are simply impossible to accomplish by any other means. Solar sail technology is rapidly advancing to support these demonstrations and missions, and in the process, is incrementally advancing one of the few approaches allowed by physics that may one day take humanity to the stars. Continuous solar pressure provides solar sails with propellantless thrust, potentially enabling them to propel a spacecraft to tremendous speeds ­ theoretically much faster than any present-day propulsion system. The next generation of sails will enable us to take our first real steps beyond the edge of the solar system, sending spacecraft out to distances of 1000 Astronomical Units, or more. In the farther term, the descendants of these first and second generation sails will augment their thrust by using high power lasers and enable travel to nearby stellar systems with flight times less than 500 years ­ a tremendous improvement over what is possible with conventional chemical rockets. By fielding these first solar sail systems, we are sneaking up on a capability to reach the stars.

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.

Experimental Study on the Propulsion Performance of the M-shape flapping wing’s bending angle

NASA Astrophysics Data System (ADS)

Chen, Jingxian; Nie, Xiaofang; Zhou, Ximing

2017-10-01

To study the the effect of flapping wing with different bending angles α on the thrust, in this paper, 9 M-shape flapping wing models with different bending angles, ranging for 0° to 22°, were designed. The rotating arm experiment was adopted to conduct the thrust test on the flapping wing models with different bending angels under the wind speed of 15m/s. The result shows that the span-wise flapping wing’s curvature could rectify the airflow, the proper curvature could prevent the span-wise airflow at the surface the flapping wing and leads the airflow towards backward, the amount of air pushed backwards by the flapping wing is larger, therefore the value of thrust is increased; As well as the rectification of M-shape flapping wing increases the thrust value, the flapping wing’s form drag also increased due to the bending angle. According to the results of the experiment, when the bending angle is less than 12°, the increment of the thrust is larger than the decrease of the form drag, so the thrust value increases gradually. However, when the bending angle is larger than 12°, the increment of the thrust is less than the decrease of the form drag, so the thrust value decreases. The thrust value is the largest when the bending angle is 12°.

Pressure and Thrust Measurements of a High-Frequency Pulsed-Detonation Actuator

NASA Technical Reports Server (NTRS)

Nguyen, Namtran C.; Cutler, Andrew D.

2008-01-01

This paper describes the development of a small-scale, high-frequency pulsed detonation actuator. The device utilized a fuel mixture of H2 and air, which was injected into the device at frequencies of up to 1200 Hz. Pulsed detonations were demonstrated in an 8-inch long combustion volume, at approx.600 Hz, for the lambda/4 mode. The primary objective of this experiment was to measure the generated thrust. A mean value of thrust was measured up to 6.0 lb, corresponding to specific impulse of 2611 s. This value is comparable to other H2-fueled pulsed detonation engines (PDEs) experiments. The injection and detonation frequency for this new experimental case was approx.600 Hz, and was much higher than typical PDEs, where frequencies are usually less than 100 Hz. The compact size of the model and high frequency of detonation yields a thrust-per-unit-volume of approximately 2.0 lb/cu in, and compares favorably with other experiments, which typically have thrust-per-unit-volume values of approximately 0.01 lb/cu in.

Ignition transient analysis of solid rocket motor

NASA Technical Reports Server (NTRS)

Han, Samuel S.

1990-01-01

To predict pressure-time and thrust-time behavior of solid rocket motors, a one-dimensional numerical model is developed. The ignition phase of solid rocket motors (time less than 0.4 sec) depends critically on complex interactions among many elements, such as rocket geometry, heat and mass transfer, flow development, and chemical reactions. The present model solves the mass, momentum, and energy equations governing the transfer processes in the rocket chamber as well as the attached converging-diverging nozzle. A qualitative agreement with the SRM test data in terms of head-end pressure gradient and the total thrust build-up is obtained. Numerical results show that the burning rate in the star-segmented head-end section and the erosive burning are two important parameters in the ignition transient of the solid rocket motor (SRM).

Apollo experience report: The application of a computerized visualization capability to lunar missions

NASA Technical Reports Server (NTRS)

Hyle, C. T.; Lunde, A. N.

1972-01-01

The development of a computerized capability to depict views from the Apollo spacecraft during a lunar mission was undertaken before the Apollo 8 mission. Such views were considered valuable because of the difficulties in visualizing the complex geometry of the Earth, Moon, Sun, and spacecraft. Such visualization capability originally was desired for spacecraft attitude verification and contingency situations. Improvements were added for later Apollo flights, and results were adopted for several real time and preflight applications. Some specific applications have included crewmember and ground control personnel familiarization, nominal and contingency mission planning, definition of secondary attitude checks for all major thrust maneuvers, and preflight star selection for navigation and for platform alinement. The use of this computerized visualization capability should prove valuable for any future space program as an aid to understanding the geometrical relationships between the spacecraft and the celestial surroundings.

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.

The Experimental Study about the Effect of Operating Conditions on Multi-tube Pulse Detonation Engine Performance

NASA Astrophysics Data System (ADS)

Kim, Jung-Min; Han, Hyung-Seok; Choi, Jeong-Yeol

2018-04-01

This study examines a multi-tube pulse detonation engine (PDE) which has a type of constant volume combustion. We designed and made the multi-tube PDE and then conducted an experiment in various operating frequencies and equivalence ratios. First, experiments with operating frequencies of 40, 80, 120, 160, and 200 Hz resulted in an average thrust and specific impulse 23.14 N and 42.34 s. The next experiment resulted in the equivalence ratio varying from 0.81 to 1.38, which resulted in an average thrust and specific impulse 22.36 N and 40.11 s. The average detonation velocity was 8% lower than that calculated according to C-J theory. The incidence ratios of the detonation wave were stable with the exception of the operating frequency of 200 Hz. However, at 200 Hz, the incidence ratio was less than 50%. We assumed that a low fill fraction occurred for this problem. The thrust of the PDE increased with the operating frequency. However, the thrust increase was at a lower rate than in previous studies, because of a lost thrust output result from the slow response time of the load cell amplifier.

Deformation of Fold-and-Thrust Belts above a Viscous Detachment: New Insights from Analogue Modelling Experiments

NASA Astrophysics Data System (ADS)

Nogueira, Carlos R.; Marques, Fernando O.

2015-04-01

Theoretical and experimental studies on fold-and-thrusts belts (FTB) have shown that, under Coulomb conditions, deformation of brittle thrust wedges above a dry frictional basal contact is characterized by dominant frontward vergent thrusts (forethrusts) with thrust spacing and taper angle being directly influenced by the basal strength (increase in basal strength leading to narrower thrust spacing and higher taper angles); whereas thrust wedges deformed above a weak viscous detachment, such as salt, show a more symmetric thrust style (no prevailing vergence of thrusting) with wider thrust spacing and shallower wedges. However, different deformation patterns can be found on this last group of thrust wedges both in nature and experimentally. Therefore we focused on the strength (friction) of the wedge basal contact, the basal detachment. We used a parallelepiped box with four fixed walls and one mobile that worked as a vertical piston drove by a computer controlled stepping motor. Fine dry sand was used as the analogue of brittle rocks and silicone putty (PDMS) with Newtonian behaviour as analogue of the weak viscous detachment. To investigate the strength of basal contact on thrust wedge deformation, two configurations were used: 1) a horizontal sand pack with a dry frictional basal contact; and 2) a horizontal sand pack above a horizontal PDMS layer, acting as a basal weak viscous contact. Results of the experiments show that: the model with a dry frictional basal detachment support the predictions for the Coulomb wedges, showing a narrow wedge with dominant frontward vergence of thrusting, close spacing between FTs and high taper angle. The model with a weak viscous frictional basal detachment show that: 1) forethrusts (FT) are dominant showing clearly an imbricate asymmetric geometry, with wider spaced thrusts than the dry frictional basal model; 2) after FT initiation, the movement on the thrust can last up to 15% model shortening, leading to great amount of displacement along the FT; 3) intermittent reactivation of FTs also occurs despite the steepening of the FT plane and existence of new FT ahead, creating a high critical taper angle; 4) injection of PDMS from the basal weak layer into the FTs planes also favours to the long living of FTs and to the high critical taper angle; 5) vertical sand thickening in the hanging block also added to the taper angle.

Thrust Augmentation Measurements for a Pulse Detonation Engine Driven Ejector

NASA Technical Reports Server (NTRS)

Pal, S.; Santoro, Robert J.; Shehadeh, R.; Saretto, S.; Lee, S.-Y.

2005-01-01

Thrust augmentation results of an ongoing study of pulse detonation engine driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE) setup with various ejector configurations. The PDE used in these experiments utilizes ethylene (C2H4) as the fuel, and an equi-molar mixture of oxygen and nitrogen as the oxidizer at an equivalence ratio of one. High fidelity thrust measurements were made using an integrated spring damper system. The baseline thrust of the PDE engine was first measured and agrees with experimental and modeling results found in the literature. Thrust augmentation measurements were then made for constant diameter ejectors. The parameter space for the study included ejector length, PDE tube exit to ejector tube inlet overlap distance, and straight versus rounded ejector inlets. The relationship between the thrust augmentation results and various physical phenomena is described. To further understand the flow dynamics, shadow graph images of the exiting shock wave front from the PDE were also made. For the studied parameter space, the results showed a maximum augmentation of 40%. Further increase in augmentation is possible if the geometry of the ejector is tailored, a topic currently studied by numerous groups in the field.

Dielectric Barrier Discharge (DBD) Plasma Actuators Thrust-Measurement Methodology Incorporating New Anti-Thrust Hypothesis

NASA Technical Reports Server (NTRS)

Ashpis, David E.; Laun, Matthew C.

2014-01-01

We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.

Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh

2005-01-01

Results of an experimental effort on pulse detonation driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE)/ejector setup that was specifically designed for the study and operated at frequencies up to 50 Hz. The results of various experiments designed to probe different aspects of the PDE/ejector setup are reported. The baseline PDE was operated using ethylene (C2H4) as the fuel and an oxygen/nitrogen O2 + N2) mixture at an equivalence ratio of one. The PDE only experiments included propellant mixture characterization using a laser absorption technique, high fidelity thrust measurements using an integrated spring-damper system, and shadowgraph imaging of the detonation/shock wave structure emanating from the tube. The baseline PDE thrust measurement results at each desired frequency agree with experimental and modeling results reported in the literature. These PDE setup results were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups with constant diameter ejector tubes and various ejector lengths, the radius of curvature for the ejector inlets and various detonation tube/ejector tube overlap distances. For the studied experimental matrix, the results showed a maximum thrust augmentation of 106% at an operational frequency of 30 Hz. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

FY98 Aero Propulsion & Power Technology Area Plan.

DTIC Science & Technology

1997-11-01

controlled area turbine nozzle (HPT & LPT) - second quarter FY98 a Fabrication/test of gamma titanium aluminide exhaust flap/liner - third quarter...both a commercial business jet and an unmanned air vehicle (Dark Star). - "Super-cooled" turbine blade designs permit 3000 F higher gas temperature for...increased thrust, or 30% reduction in blade cooling air for reduced fuel consumption, or two-to four- fold increase in turbine blade life - all at a

Propeller thrust analysis using Prandtl's lifting line theory, a comparison between the experimental thrust and the thrust predicted by Prandtl's lifting line theory

NASA Astrophysics Data System (ADS)

Kesler, Steven R.

The lifting line theory was first developed by Prandtl and was used primarily on analysis of airplane wings. Though the theory is about one hundred years old, it is still used in the initial calculations to find the lift of a wing. The question that guided this thesis was, "How close does Prandtl's lifting line theory predict the thrust of a propeller?" In order to answer this question, an experiment was designed that measured the thrust of a propeller for different speeds. The measured thrust was compared to what the theory predicted. In order to do this experiment and analysis, a propeller needed to be used. A walnut wood ultralight propeller was chosen that had a 1.30 meter (51 inches) length from tip to tip. In this thesis, Prandtl's lifting line theory was modified to account for the different incoming velocity depending on the radial position of the airfoil. A modified equation was used to reflect these differences. A working code was developed based on this modified equation. A testing rig was built that allowed the propeller to be rotated at high speeds while measuring the thrust. During testing, the rotational speed of the propeller ranged from 13-43 rotations per second. The thrust from the propeller was measured at different speeds and ranged from 16-33 Newton's. The test data were then compared to the theoretical results obtained from the lifting line code. A plot in Chapter 5 (the results section) shows the theoretical vs. actual thrust for different rotational speeds. The theory over predicted the actual thrust of the propeller. Depending on the rotational speed, the error was: at low speeds 36%, at low to moderate speeds 84%, and at high speeds the error increased to 195%. Different reasons for these errors are discussed.

Viscoplastic analysis of an experimental cylindrical thrust chamber liner

NASA Technical Reports Server (NTRS)

Arya, Vinod K.; Arnold, Steven M.

1991-01-01

A viscoplastic stress-strain analysis of an experimental cylindrical thrust chamber is presented. A viscoelastic constitutive model incorporating a single internal state variable that represents kinematic hardening was employed to investigate whether such a viscoplastic model could predict the experimentally observed behavior of the thrust chamber. Two types of loading cycles were considered: a short cycle of 3.5 sec. duration that corresponded to the experiments, and an extended loading cycle of 485.1 sec. duration that is typical of the Space Shuttle Main Engine (SSME) operating cycle. The analysis qualitatively replicated the deformation behavior of the component as observed in experiments designed to simulate SSME operating conditions. The analysis also showed that the mode and location in the component may depend on the loading cycle. The results indicate that using viscoplastic models for structural analysis can lead to a more realistic life assessment of thrust chambers.

Thrust generation experiments on microwave rocket with a beam concentrator for long distance wireless power feeding

NASA Astrophysics Data System (ADS)

Fukunari, Masafumi; Yamaguchi, Toshikazu; Nakamura, Yusuke; Komurasaki, Kimiya; Oda, Yasuhisa; Kajiwara, Ken; Takahashi, Koji; Sakamoto, Keishi

2018-04-01

Experiments using a 1 MW-class gyrotron were conducted to examine a beamed energy propulsion rocket, a microwave rocket with a beam concentrator for long-distance wireless power feeding. The incident beam is transmitted from a beam transmission mirror system. The beam transmission mirror system expands the incident beam diameter to 240 mm to extend the Rayleigh length. The beam concentrator receives the beam and guides it into a 56-mm-diameter cylindrical thruster tube. Plasma ignition and ionization front propagation in the thruster were observed through an acrylic window using a fast-framing camera. Atmospheric air was used as a propellant. Thrust generation was achieved with the beam concentrator. The maximum thrust impulse was estimated as 71 mN s/pulse from a pressure history at the thrust wall at the input energy of 638 J/pulse. The corresponding momentum coupling coefficient, Cm was inferred as 204 N/MW.

Episodic growth of fold-thrust belts: Insights from Finite Element Modelling

NASA Astrophysics Data System (ADS)

Yang, Xiaodong; Peel, Frank J.; Sanderson, David J.; McNeill, Lisa C.

2017-09-01

The sequential development of a fold-thrust belt was investigated using 2D Finite Element Modelling (FEM). The new model results show that a thrust system is typically composed of three distinct regions: the thrust wedge, pre-wedge, and undeformed region. The thrust wedge involves growth that repeats episodically and cyclically. A cycle of wedge building starts as frontal accretion occurs, which is accompanied by a rapid increase in wedge width reducing the taper angle below critical. In response to this, the wedge interior (tracked here by the 50 m displacement position) rapidly propagates forwards into a region of incipient folding. The taper angle progressively increases until it obtains a constant apparent critical value (∼10°). During this period, the wedge experiences significant shortening after a new thrust initiates at the failure front, leading to a decrease in wedge width. Successive widening of the wedge and subsequent shortening and thrusting maintain a reasonably constant taper angle. The fold-thrust belt evolves cyclically, through a combination of rapid advancement of the wedge and subsequent gradual, slow wedge growth. The new model results also highlights that there is clear, although minor, deformation (0-10 m horizontal displacement) in front of the thrust wedge.

Upper crustal mechanical stratigraphy and the evolution of thrust wedges: insights from sandbox analogue experiments

NASA Astrophysics Data System (ADS)

Milazzo, Flavio; Storti, Fabrizio; Nestola, Yago; Cavozzi, Cristian; Magistroni, Corrado; Meda, Marco; Salvi, Francesca

2016-04-01

Crustal mechanical stratigraphy i.e. alternating mechanically weaker and stronger layers within the crust, plays a key role in determining how contractional deformations are accommodated at convergent plate boundaries. In the upper crust, evaporites typically provide preferential décollement layers for fault localization and foreland ward propagation, thus significantly influencing evolution of thrust-fold belts in terms of mechanical balance, geometries, and chronological sequences of faulting. Evaporites occur at the base of many passive margin successions that underwent positive inversion within orogenic systems. They typically produce salient geometries in deformation fronts, as in the Jura in the Northern Alps, the Salakh Arch in the Oman Mountains, or the Ainsa oblique thrust-fold belt in the Spanish Pyrenees. Evaporites frequently occur also in foredeep deposits, as in the Apennines, the Pyrenees, the Zagros etc. causing development of additional structural complexity. Low-friction décollement layers also occur within sedimentary successions involved in thrust-fold belts and they contribute to the development of staircase fault trajectories. The role of décollement layers in thrust wedge evolution has been investigated in many experimental works, particularly by sandbox analogue experiments that have demonstrated the impact of basal weak layers on many first order features of thrust wedges, including the dominant fold vergence, the timing of fault activity, and the critical taper. Some experiments also investigated on the effects of weak layers within accreting sedimentary successions, showing how this triggers kinematic decoupling of the stratigraphy above and below the décollements, thus enhancing disharmonic deformation. However, at present a systematic experimental study of the deformation modes of an upper crustal mechanical stratigraphy consisting of both low-friction and viscous décollement layers is still missing in the specific literature. In this contribution we present the results of such a study, where a three-décollement mechanical stratigraphy has been deformed in the sandbox at the same boundary conditions. Different rheological properties were assigned to the three décollements in different experiments, up to testing all possible mechanical stratigraphies. Implications on thrust propagation and slip rate history and cross-sectional thrust wedge architecture are discussed and compared with natural cases.

Multi-Axis Thrust Measurements of the EO-1 Pulsed Plasma Thruster

NASA Technical Reports Server (NTRS)

Arrington, Lynn A.; Haag, Thomas W.

1999-01-01

Pulsed plasma thrusters are low thrust propulsive devices which have a high specific impulse at low power. A pulsed plasma thruster is currently scheduled to fly as an experiment on NASA's Earth Observing-1 satellite mission. The pulsed plasma thruster will be used to replace one of the reaction wheels. As part of the qualification testing of the thruster it is necessary to determine the nominal thrust as a function of charge energy. These data will be used to determine control algorithms. Testing was first completed on a breadboard pulsed plasma thruster to determine nominal or primary axis thrust and associated propellant mass consumption as a function of energy and then later to determine if any significant off-axis thrust component existed. On conclusion that there was a significant off-axis thrust component with the bread-board in the direction of the anode electrode, the test matrix was expanded on the flight hardware to include thrust measurements along all three orthogonal axes. Similar off-axis components were found with the flight unit.

Use of magnetic sails for advanced exploration missions

NASA Technical Reports Server (NTRS)

Andrews, Dana G.; Zubrin, Robert M.

1990-01-01

The magnetic sail, or magsail, is a field effect device which interacts with the ambient solar wind or interstellar medium over a considerable volume of space to generate drag and lift forces. Two theories describing the method of thrust generation are analyzed and data results are presented. The techniques for maintaining superconductor temperatures in interplanetary space are analyzed and low risk options presented. Comparisons are presented showing mission performance differences between currently proposed spacecraft using chemical and electric propulsion systems, and a Magsail propelled spacecraft capable of generating an average thrust of 250 Newtons at a radius of one A.U. The magsail also provides unique capabilities for interstellar missions, in that at relativistic speeds the magnetic field would ionize and deflect the interstellar medium producing a large drag force. This would make it an ideal brake for decelerating a spacecraft from relativistic speeds and then maneuvering within the target star system.

Experimental Study of a Pulse Detonation Engine Driven Ejector

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh; Shehadeh, R.; Saretto, S.; Lee, S.-Y.

2005-01-01

Results of an experimental effort on pulse detonation driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE)/ejector setup that was specifically designed for the study. The results of various experiments designed to probe different aspects of the PDE/ejector setup are reported. The baseline PDE was operated using ethylene (C2H4) as the fuel and an oxygen/nitrogen (O2 + N2) mixture at an equivalence ratio of one. The PDE only experiments included propellant mixture characterization using a laser absorption technique, high fidelity thrust measurements using an integrated spring-damper system, and shadowgraph imaging of the detonation/shock wave structure emanating from the tube. The baseline PDE thrust measurement results are in excellent agreement with experimental and modeling results reported in the literature. These PDE setup results were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups with constant diameter ejector tubes and various detonation tube/ejector tube overlap distances. The results show that for the geometries studied here, a maximum thrust augmentation of 24% is achieved. Further increases are possible by tailoring the ejector geometry based on CFD predictions conducted elsewhere. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

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.

Supervisory control of drilling of composite materials

NASA Astrophysics Data System (ADS)

Ozaki, Motoyoshi

Composite materials have attractive features, such as high ratios of strength-to-weight and stiffness-to-weight. However, they are easily damaged when they are machined. A typical damage is delamination, which can occur when fiber reinforced composite laminates are drilled. The objective of this research is to study the drilling processes of carbon fiber reinforced laminates, and to develop and test a supervisory control strategy for their delamination-free drilling. Characterization of thrust force and torque is achieved through constant feedrate drilling experiments. The average values of thrust force and torque during the full engagement of the drill are utilized to obtain the Shaw's equations' parameters. The thrust force profile just before exit is given special attention. The Hocheng-Dharan equations, which give conservative values of delamination at the entrance and at the exit, are modified to express the influence of one lamina thickness explicitly. They are utilized not only for the characterization of thrust force but also for the determination of the thrust force reference for force control. In the design of the controllers of thrust force and torque, both thrust force and torque are assumed to be proportional to FPHR (Feed Per Half Revolution). A discrete-time dynamic model is established for the case when the time interval for a half revolution of the drill is divided by the sampling time, and the model is extended to the case of general spindle speeds. PI controllers are designed for the dynamic models of thrust force and torque. Root-locus techniques are used in the analysis. The phases of the drilling process are introduced and the control strategy at each phase is explained. The supervisory controller chooses not only the best control strategy for each phase, but also the reference value and the controller gain that are suitable at each drill position. Drilling experiments are conducted to show the usefulness of the concepts introduced in this dissertation, and to give an example of installing the control parameters, which were derived from data obtained in this research, on the supervisory controller. Efficient Delamination-free drilling is given special emphasis in the experiments.

Capabilities of a Laser Guide Star for a Large Segmented Space Telescope

NASA Astrophysics Data System (ADS)

Clark, James R.; Carlton, Ashley; Douglas, Ewan S.; Males, Jared R.; Lumbres, Jennifer; Feinberg, Lee; Guyon, Olivier; Marlow, Weston; Cahoy, Kerri L.

2018-01-01

Large segmented mirror telescopes are planned for future space telescope missions such as LUVOIR (Large UV Optical Infrared Surveyor) to enable the improvement in resolution and contrast necessary to directly image Earth-like exoplanets, in addition to making contributions to general astrophysics. The precision surface control of these complex, large optical systems, which may have over a hundred meter-sized segments, is a challenge. Our initial simulations show that imaging a star of 2nd magnitude or brighter with a Zernike wavefront sensor should relax the segment stability requirements by factors between 10 and 50 depending on the wavefront control strategy. Fewer than fifty stars brighter than magnitude 2 can be found in the sky. A laser guide star (LGS) on a companion spacecraft will allow the telescope to target a dimmer science star and achieve wavefront control to the required stability without requiring slew or repointing maneuvers.We present initial results for one possible mission architecture, with a LGS flying at 100,000 km range from the large telescope in an L2 halo orbit, using a laser transmit power of <10 W. We also discuss orbital dynamics and propulsion options for a LGS. Our initial analysis in MATLAB simulations finds that the telescope-LGS vector can be held anywhere on the sky for extended durations (>8 days) for an expenditure of <10 m/s of delta-V per day, or an average thrust <1 mN for a satellite of mass <47 kg. If the LGS uses a low-thrust electric propulsion system, it can be accommodated in a 6U CubeSat bus, but may require an extended period of time to transition between targets and match velocities with the telescope (e.g. 6 days to transit 10 degrees). If the LGS uses monopropellant propulsion, it must use at least a 27U bus to achieve the the same delta-V capability, but can transition between targets much more rapidly (<1 day to transit 10 degrees).Architecture trades on formation flying distance, laser wavelength and power are ongoing. The models of the segments and their disturbances and of the formation flight are being refined. A low-cost prototype mission (e.g. between a small satellite in LEO and an LGS in GEO) to validate the feasibility is in development.

Experimental demonstration of ion extraction from magnetic thrust chamber for laser fusion rocket

NASA Astrophysics Data System (ADS)

Saito, Naoya; Yamamoto, Naoji; Morita, Taichi; Edamoto, Masafumi; Nakashima, Hideki; Fujioka, Shinsuke; Yogo, Akifumi; Nishimura, Hiroaki; Sunahara, Atsushi; Mori, Yoshitaka; Johzaki, Tomoyuki

2018-05-01

A magnetic thrust chamber is an important system of a laser fusion rocket, in which the plasma kinetic energy is converted into vehicle thrust by a magnetic field. To investigate the plasma extraction from the system, the ions in a plasma are diagnosed outside the system by charge collectors. The results clearly show that the ion extraction does not strongly depend on the magnetic field strength when the energy ratio of magnetic field to plasma is greater than 4.3, and the magnetic field pushes back the plasma to generate a thrust, as previously suggested by numerical simulation and experiments.

Effect of Operating Frequency on PDE Driven Ejector Thrust Performance

NASA Technical Reports Server (NTRS)

Santoro, Robert J.; Pal, Sibtosh; Landry, K.; Shehadeh, R.; Bouvet, N.; Lee, S.-Y.

2005-01-01

Results of an on-going study of pulse detonation engine driven ejectors are presented and discussed. The experiments were conducted using a pulse detonation engine (PDE) designed to operate at frequencies up to 50 Hz. The PDE used in these experiments utilizes an equi-molar mixture of oxygen and nitrogen as the oxidizer, and ethylene (C2H4) as the fuel, with the propellant mixture having an equivalence ratio of one. A line of sight laser absorption technique was used to determine the time needed for proper filling of the tube. Thrust measurements were made using an integrated spring damper system coupled with a linear variable displacement transducer. The baseline thrust of the PDE was first measured at each desired frequency and agrees with experimental and modeling results found in the literature. Thrust augmentation measurements were then made for constant diameter ejectors. The ejectors had varying lengths, and two different inlet geometries were tested for each ejector configuration. The parameter space for the study included PDE operation frequency, ejector length, overlap distance and the radius of curvature for the ejector inlets. For the studied experimental matrix, the results showed a maximum thrust augmentation of 106% at an operational frequency of 30 Hz.

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.

Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators: New Anti-Thrust Hypothesis, Frequency Sweeps Methodology, Humidity and Enclosure Effects

NASA Technical Reports Server (NTRS)

Ashpis, David E.; Laun, Matthew C.

2014-01-01

We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust, or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a grounded large-diameter metal sleeve. Strong dependence on humidity is also shown; the thrust significantly increased with decreasing humidity, e.g., 44 percent increase as relative humidity changed from 18 percent and dew point 33 degF to 50 percent and dew point of 57 degF.

Effect of Operating Frequency and Fill Time on PDE-Ejector Thrust Performance

NASA Technical Reports Server (NTRS)

Landry, K.; Santoro, Robert J.; Pal, Sibtosh; Shehadeh, R.; Bouvet, N.; Lee, S.-Y.

2005-01-01

Thrust measurements for a pulse detonation engine (PDE)-ejector system were determined for a range of operating frequencies. Various length tubular ejectors were utilized. The results were compared to the measurements of the thrust output of the PDE alone to determine the enhancement provided by each ejector configuration at the specified frequencies. Ethylene was chosen as the fuel, with an equi-molar mixture of nitrogen and oxygen acting as the oxidizer. The propellant was kept at an equivalence ratio of one during all the experiments. The system was operated for frequencies between 20 and 50 Hz. The parameter space of the study included PDE operation frequency, ejector length, overlap percentage, the radius of curvature for the ejector inlets, and duration of the time allowed between cycles. The results of the experiments showed a maximum thrust augmentation of 120% for a PDE-ejector configuration at a frequency of 40Hz with a fill time of 10 ms.

Q14 - Standards Development Plan, Ada Interfaces to X Window System, Analysis and Recommendations

DTIC Science & Technology

1989-03-20

portability and reusability. -, . /- , ... ’ 4t. I-,: 2 Introduction Two major thrusts of the STARS program, and industry as a whole, are application...and IEEE, and in industry consortiums to show the directions X is taking and the opportunities for Ada to utilize this work. X is not the only window...and actually prohibit portability, but to avoid this the X developers formed the X Consortium, consisting of industry and academic members, who define

Comparisons between a high resolution discrete element model and analogue model

NASA Astrophysics Data System (ADS)

LI, C. S.; Yin, H.; WU, C.; Zhang, J.

2017-12-01

A two-dimensional discrete element model (DEM) with high resolution is constructed to simulate the evolution of thrust wedge and an analogue model (AM) experiment is constructed to compare with the DEM results. This efficient parallel DEM program is written in the C language, and it is useful to solve the complex geological problems. More detailed about fold and thrust belts of DEM can be identified with the help of strain field. With non-rotating and non-tensile assumption, dynamic evolution of DEM is highly consistent with AM. Simulations in different scale can compare with each other by conversion formulas in DEM. Our results show that: (1) The overall evolution of DEM and AM is broadly similar. (2) Shortening is accommodated by in-sequence forward propagation of thrusts. The surface slope of the thrust wedge is within the stable field predicted by critical taper theory. (3) Details of thrust spacing, dip angle and number of thrusts vary between DEM and AM for the shortening experiment, but the characteristics of thrusts are similar on the whole. (4) Dip angles of the forward thrusts increased from foreland (ca. 30°) to the mobile wall (ca. 80°) (5) With shortening, both models had not the obvious volume loss. Instead, the volume basic remained unchanged in the whole extrusion processes. (6) Almost all high strain values are within fold-and-thrust belts in DEM, which allows a direct comparison between the fault zone identified on the DEM deformation field and that in the strain field. (7) The first fault initiates at deep depths and propagate down toward the surface. For the maximal volumetric strain focused on the décollement near the mobile wall, strengthening the material and making it for brittle. (8) With non-tensile particles for DEM, contraction is broadly distributed throughout the model and dilation is hardly any, which also leads to a higher efficient computation. (9) High resolution DEM can to first order successfully reproduce structures observed in AM. The comparisons serve to highlight robust features in tectonic modelling of thrust wedges. This approach is very utility in modelling large displacement, complex deformation of analogue and geological materials.

Friction torque in thrust ball bearings grease lubricated

NASA Astrophysics Data System (ADS)

Ianuş, G.; Dumitraşcu, A. C.; Cârlescu, V.; Olaru, D. N.

2016-08-01

The authors investigated experimentally and theoretically the friction torque in a modified thrust ball bearing having only 3 balls operating at low axial load and lubricated with NGLI-00 and NGLI-2 greases. The experiments were made by using spin-down methodology and the results were compared with the theoretical values based on Biboulet&Houpert's rolling friction equations. Also, the results were compared with the theoretical values obtained with SKF friction model adapted for 3 balls. A very good correlation between experiments and Biboulet_&_Houpert's predicted results was obtained for the two greases. Also was observed that the theoretical values for the friction torque calculated with SKF model adapted for a thrust ball bearing having only 3 balls are smaller that the experimental values.

Modes of thrust generation in flying animals

NASA Astrophysics Data System (ADS)

Luo, Haoxiang; Song, Jialei; Tobalske, Bret; Luo Team; Tobalske Team

2016-11-01

For flying animals in forward flight, thrust is usually much smaller as compared with weight support and has not been given the same amount of attention. Several modes of thrust generation are discussed in this presentation. For insects performing slow flight that is characterized by low advance ratios (i.e., the ratio between flight speed and wing speed), thrust is usually generated by a "backward flick" mode, in which the wings moves upward and backward at a faster speed than the flight speed. Paddling mode is another mode used by some insects like fruit flies who row their wings backward during upstroke like paddles (Ristroph et al., PRL, 2011). Birds wings have high advance ratios and produce thrust during downstroke by directing aerodynamic lift forward. At intermediate advance ratios around one (e.g., hummingbirds and bats), the animal wings generate thrust during both downstroke and upstroke, and thrust generation during upstroke may come at cost of negative weight support. These conclusions are supported by previous experiment studies of insects, birds, and bats, as well as our recent computational modeling of hummingbirds. Supported by the NSF.

Effect of applied magnetic nozzle on an MPD Thruster

NASA Astrophysics Data System (ADS)

Ando, Akira; Izawa, Yuki; Okawa, Kohei; Hashima, Yoko; Watanabe, Hiroshi; Tanaka, Nozomi

2012-10-01

Electric propulsion systems are suitable for long-term mission in space due to its higher specific impulse. An Magneto-Plasma-Dynamic Thruster (MPDT) is one of the promising thrusters of high power electric propulsion systems. It has been reported that the thrust performance of an MPDT can be improved by applying an axial magnetic field on it. In order to investigate the effect of applied field on an MPDT, we have investigated plume plasma parameters and thrust performance in an applied field MPDT. Different types of divergent magnetic nozzle were applied to an MPDT, and thrust was measured using a pendulum type thrust target. Experiments were performed with hydrogen, helium, and argon as propellant gas. Thrust increased with a discharge current up to 6kA and applied magnetic field up to 0.4T. Maximum thrust of 7N was obtained when the peak position of the applied magnetic field was set upstream of the muzzle of the MPDT. The highest thrust performance was obtained with hydrogen gas with divergent magnetic nozzle applied to the MPDT.

Parametric Investigation of Thrust Augmentation by Ejectors on a Pulsed Detonation Tube

NASA Technical Reports Server (NTRS)

Wilson, Jack; Sgondea, Alexandru; Paxson, Daniel E.; Rosenthal, Bruce N.

2006-01-01

A parametric investigation has been made of thrust augmentation of a 1 in. diameter pulsed detonation tube by ejectors. A set of ejectors was used which permitted variation of the ejector length, diameter, and nose radius, according to a statistical design of experiment scheme. The maximum augmentation ratios for each ejector were fitted using a polynomial response surface, from which the optimum ratios of ejector diameter to detonation tube diameter, and ejector length and nose radius to ejector diameter, were found. Thrust augmentation ratios above a factor of 2 were measured. In these tests, the pulsed detonation device was run on approximately stoichiometric air-hydrogen mixtures, at a frequency of 20 Hz. Later measurements at a frequency of 40 Hz gave lower values of thrust augmentation. Measurements of thrust augmentation as a function of ejector entrance to detonation tube exit distance showed two maxima, one with the ejector entrance upstream, and one downstream, of the detonation tube exit. A thrust augmentation of 2.5 was observed using a tapered ejector.

Hydrodynamic aspects of thrust generation in gymnotiform swimming

NASA Astrophysics Data System (ADS)

Shirgaonkar, Anup A.; Curet, Oscar M.; Patankar, Neelesh A.; Maciver, Malcolm A.

2008-11-01

The primary propulsor in gymnotiform swimmers is a fin running along most of the ventral midline of the fish. The fish propagates traveling waves along this ribbon fin to generate thrust. This unique mode of thrust generation gives these weakly electric fish great maneuverability cluttered spaces. To understand the mechanical basis of gymnotiform propulsion, we investigated the hydrodynamics of a model ribbon-fin of an adult black ghost knifefish using high-resolution numerical experiments. We found that the principal mechanism of thrust generation is a central jet imparting momentum to the fluid with associated vortex rings near the free edge of the fin. The high-fidelity simulations also reveal secondary vortex rings potentially useful in rapid sideways maneuvers. We obtained the scaling of thrust with respect to the traveling wave kinematic parameters. Using a fin-plate model for a fish, we also discuss improvements to Lighthill's inviscid theory for gymnotiform and balistiform modes in terms of thrust magnitude, viscous drag on the body, and momentum enhancement.

Parametric Investigation of Thrust Augmentation by Ejectors on a Pulsed Detonation Tube

NASA Technical Reports Server (NTRS)

Wilson, Jack; Sgondea, Alexandru; Paxson, Daniel E.; Rosenthal, Bruce N.

2005-01-01

A parametric investigation has been made of thrust augmentation of a 1 inch diameter pulsed detonation tube by ejectors. A set of ejectors was used which permitted variation of the ejector length, diameter, and nose radius, according to a statistical design of experiment scheme. The maximum augmentations for each ejector were fitted using a polynomial response surface, from which the optimum ejector diameters, and nose radius, were found. Thrust augmentations above a factor of 2 were measured. In these tests, the pulsed detonation device was run on approximately stoichiometric air-hydrogen mixtures, at a frequency of 20 Hz. Later measurements at a frequency of 40 Hz gave lower values of thrust augmentation. Measurements of thrust augmentation as a function of ejector entrance to detonation tube exit distance showed two maxima, one with the ejector entrance upstream, and one downstream, of the detonation tube exit. A thrust augmentation of 2.5 was observed using a tapered ejector.

Planned Axial Reorientation Investigation on Sloshsat

NASA Technical Reports Server (NTRS)

Chato, David J.

2000-01-01

This paper details the design and logic of an experimental investigation to study axial reorientation in low gravity. The Sloshsat free-flyer is described. The planned axial reorientation experiments and test matrixes are presented. Existing analytical tools are discussed. Estimates for settling range from 64 to 1127 seconds. The planned experiments are modelled using computational fluid dynamics. These models show promise in reducing settling estimates and demonstrate the ability of pulsed high thrust settling to emulate lower thrust continuous firing.

Republic F-84 Thunderjet with Reverse Thruster

NASA Image and Video Library

1954-06-21

The US Air Force loaned a Republic F-84 Thunderjet to the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory in the spring of 1954. NACA researchers soon modified the aircraft for the first demonstration of a reverse thruster. Republic built over 4000 Thunderjets between 1947 and 1953 for the military as a successor to the Lockheed F-80 Shooting Star. TheF-84s became successful multi-use aircraft during the Korean War. The use of traditional wheel brakes on high speed aircraft was problematic because the required braking system would weigh too much. The reverse thruster was developed as a method for stopping these aircraft without increasing the overall weight. Panels in the tail section near the jet engine’s nozzle opened up during a landing. These extended flaps not only caused resistance to the airstream but also reversed the engine’s thrust. In June 1964 Irving Pinkel, head of the Lewis Physics Division, oversaw a demonstration of this technology on an F-84 at the NACA laboratory. The side fuselage panels around the engine nozzle, seen closed in this photograph, opened up like wings and deflected the engine’s thrust towards the front of the aircraft, thus producing reverse thrust. The F-84 activated the reverse thruster and the aircraft moved backwards across the runway.

Experimental study on the thrust modulation performance of powdered magnesium and CO2 bipropellant engine

NASA Astrophysics Data System (ADS)

Li, Chao; Hu, Chunbo; Zhu, Xiaofei; Hu, Jiaming; Li, Yue; Hu, Xu

2018-06-01

Powdered Mg and CO2 bipropellant engine providing a practical demonstration of in situ resource utilization (ISRU) for Mars Sample Return (MSR) mission seems to be feasible by current investigations. However, essential functions of the engine to satisfy the complicated ballistics requirements such as thrust modulation and multiple pulse have not been established yet. The aim of this experimental study is to evaluate the engine's thrust modulation feasibility and to investigate its thrust modulation characteristics. A powdered Mg and CO2 bipropellant engine construction aiming to achieve thrust modulation ability was proposed. A mass flow rate calibration experiment to evaluate the gas-solid mass flow rate regulating performance was conducted before fire tests. Fire test result shows that the engine achieved successful ignition as well as self-sustaining combustion; Thrust modulation of the engine is feasible, detail thrust estimating result of the test shows that maximum thrust is 135.91 N and the minimum is 5.65 N with a 22.11 thrust modulation ratio, moreover, the transportation period is quick and the thrust modulation ratio is adjustable. At the same time, the powder feed system reaches a two-step flow rate regulating with a modulation ratio of 4.5-5. What' more, caused by the uneven engine working conditions, there is an obvious difference in combustion efficiency value, maximum combustion efficiency of the powdered Mg and CO2 bipropellant engine is 80.20%.

Experimental verification of high energy laser-generated impulse for remote laser control of space debris.

PubMed

Lorbeer, Raoul-Amadeus; Zwilich, Michael; Zabic, Miroslav; Scharring, Stefan; Eisert, Lukas; Wilken, Jascha; Schumacher, Dennis; Roth, Markus; Eckel, Hans-Albert

2018-05-31

Walking along a beach one may notice debris being washed ashore from the vast oceans. Then, turning your head up at night you even might noticed a shooting star or a bright spot passing by. Chances are, that you witnessed space debris, endangering future space flight in lower earth orbit. If it was possible to turn cm-sized debris into shooting stars the problem might be averted. Unfortunately, these fragments counting in the 100 thousands are not controllable. To possibly regain control we demonstrate how to exert forces on a free falling debris object from a distance by ablating material with a high energy ns-laser-system. Thrust effects did scale as expected from simulations and led to speed gains above 0.3 m/s per laser pulse in an evacuated micro-gravity environment.

Analogue modelling of thrust systems: Passive vs. active hanging wall strain accommodation and sharp vs. smooth fault-ramp geometries

NASA Astrophysics Data System (ADS)

Rosas, F. M.; Duarte, J. C.; Almeida, P.; Schellart, W. P.; Riel, N.; Terrinha, P.

2017-06-01

We present new analogue modelling results of crustal thrust-systems in which a deformable (brittle) hanging wall is assumed to endure passive internal deformation during thrusting, i.e. exclusively as a consequence of having to adapt its shape to the variable geometry of a rigid footwall. Building on previous experimental contributions, we specifically investigate the role of two so far overlooked critical variables: a) concave-convex (CC) vs. flat-ramp-flat (FRF) thrust ramp geometry; and b) presence vs. absence of a basal velocity discontinuity (VD). Regarding the first variable, we compare new results for considered (CC) smoother ramp types against classical experiments in which (FRF) sharp ramp geometries are always prescribed. Our results show that the considered sharp vs. smooth variation in the thrust-ramp geometry produces important differences in the distribution of the local stress field in the deformable hanging wall above both (lower and upper) fault bends, with corresponding styles of strain accommodation being expressed by marked differences in measured morpho-structural parameters. Regarding the second variable, we for the first time report analogue modelling results of this type of experiments in which basal VDs are experimentally prescribed to be absent. Our results critically show that true passive hanging wall deformation is only possible to simulate in the absence of any basal VD, since active shortening accommodation always necessarily occurs in the hanging wall above such a discontinuity (i.e. above the lower fault bend). In addition, we show that the morpho-structural configuration of model thrust-wedges formed for prescribed VD absence conditions complies well with natural examples of major overthrusts, wherein conditions must occur that approximate a frictionless state along the main basal thrust-plane.

Upper Stage Flight Experiment 10K Engine Design and Test Results

NASA Technical Reports Server (NTRS)

Ross, R.; Morgan, D.; Crockett, D.; Martinez, L.; Anderson, W.; McNeal, C.

2000-01-01

A 10,000 lbf thrust chamber was developed for the Upper Stage Flight Experiment (USFE). This thrust chamber uses hydrogen peroxide/JP-8 oxidizer/fuel combination. The thrust chamber comprises an oxidizer dome and manifold, catalyst bed assembly, fuel injector, and chamber/nozzle assembly. Testing of the engine was done at NASA's Stennis Space Center (SSC) to verify its performance and life for future upper stage or Reusable Launch Vehicle applications. Various combinations of silver screen catalyst beds, fuel injectors, and combustion chambers were tested. Results of the tests showed high C* efficiencies (97% - 100%) and vacuum specific impulses of 275 - 298 seconds. With fuel film cooling, heating rates were low enough that the silica/quartz phenolic throat experienced minimal erosion. Mission derived requirements were met, along with a perfect safety record.

Thrust-wrench fault interference in a brittle medium: new insights from analogue modelling experiments

NASA Astrophysics Data System (ADS)

Rosas, Filipe; Duarte, Joao; Schellart, Wouter; Tomas, Ricardo; Grigorova, Vili; Terrinha, Pedro

2015-04-01

We present analogue modelling experimental results concerning thrust-wrench fault interference in a brittle medium, to try to evaluate the influence exerted by different prescribed interference angles in the formation of morpho-structural interference fault patterns. All the experiments were conceived to simulate simultaneous reactivation of confining strike-slip and thrust faults defining a (corner) zone of interference, contrasting with previously reported discrete (time and space) superposition of alternating thrust and strike-slip events. Different interference angles of 60°, 90° and 120° were experimentally investigated by comparing the specific structural configurations obtained in each case. Results show that a deltoid-shaped morpho-structural pattern is consistently formed in the fault interference (corner) zone, exhibiting a specific geometry that is fundamentally determined by the different prescribed fault interference angle. Such angle determines the orientation of the displacement vector shear component along the main frontal thrust direction, determining different fault confinement conditions in each case, and imposing a complying geometry and kinematics of the interference deltoid structure. Model comparison with natural examples worldwide shows good geometric and kinematic similarity, pointing to the existence of matching underlying dynamic process. Acknowledgments This work was sponsored by the Fundação para a Ciência e a Tecnologia (FCT) through project MODELINK EXPL/GEO-GEO/0714/2013.

Episodic Growth of Fold-Thrust Belts: Insights from Finite Element Modelling

NASA Astrophysics Data System (ADS)

Yang, X.; Peel, F.; Sanderson, D. J.; McNeill, L. C.

2016-12-01

The sequential development of an imbricate thrust system was investigated using a set of 2D FEM models. This study provides new insights on how the style and location of thrust activity changes through cycles of thrust accretion by making refined measurements of the thrust system parameters through time and tracking these parameters through each cycle. In addition to conventional wedge parameters (i.e. surface slope, wedge width and height), the overall taper angle is used to determine how the critical taper angle is reached; a particular focus is on the region of outboard minor horizontal displacement provides insights into the forward propagation of material within, and in front of, the thrust wedge; tracking the position of the failure front (where the frontal thrust roots into the basal detachment) reveals the sequence and advancement of the imbricate thrusts. The model results show that a thrust system is generally composed of three deformation components: thrust wedge, pre-wedge and wedge front. A thrust belt involves growth that repeats episodically and cyclically. When a wedge reaches critical taper ( 10°), thrust movement within the wedge slows while the taper angle and wedge width gradually increase. In contrast, the displacement front (tracked here by the location of 0 m displacement) rapidly propagates forward along whilst the wedge height is fast growing. During this period, the wedge experiences a significant shortening after a new thrust initiates at the failure front, leading to an obvious decrease in wedge width. As soon as the critical taper is achieved, wedge interior (tracked here by the location of 50 m displacement) accelerates forward reducing the taper angle below critical. This is accompanied by a sudden increase in wedge width, slow advancement of displacement front, and slow uplift of the fold-thrust belt. The rapid movements within and in front of the wedge occur alternately. The model results also show that there is clear, although minor, activity (5-10 m displacement) in front of the thrust wedge, which distinguishes the failure front from the displacement front throughout the fold-thrust belt development. This spatial and temporal relationship may not have been previously recognized in natural systems.

Design and Fabrication of a 200N Thrust Rocket Motor Based on NH4ClO4+Al+HTPB as Solid Propellant

NASA Astrophysics Data System (ADS)

Wahid, Mastura Ab; Ali, Wan Khairuddin Wan

2010-06-01

The development of rocket motor using potassium nitrate, carbon and sulphur mixture has successfully been developed by researchers and students from UTM and recently a new combination for solid propellant is being created. The new solid propellant will combine a composition of Ammonium perchlorate, NH4ClO4 with aluminium, Al and Hydroxyl Terminated Polybutadiene, HTPB as the binder. It is the aim of this research to design and fabricate a new rocket motor that will produce a thrust of 200N by using this new solid propellant. A static test is done to obtain the thrust produced by the rocket motor and analyses by observation and also calculation will be done. The experiment for the rocket motor is successful but the thrust did not achieve its required thrust.

Tailoff thrust and impulse imbalance between pairs of Space Shuttle solid rocket motors

NASA Technical Reports Server (NTRS)

Jacobs, E. P.; Yeager, J. M.

1975-01-01

The tailoff thrust and impulse imbalance between pairs of solid rocket motors is of particular interest for the Space Shuttle Vehicle because of the potential control problems that exist with this asymmetric configuration. Although a similar arrangement of solid rocket motors was utilized for the Titan Program, they produced less than one-half the thrust level of the Space Shuttle at web action time, and the overall vehicle was symmetric. Since the Titan Program does provide the most applicable actual test data, 23 flight pairs were analyzed to determine the actual tailoff thrust and impulse imbalance experienced. The results were scaled up using the predicted web action time thrust and tailoff time to arrive at values for the Space Shuttle. These values were then statistically treated to obtain a prediction of the maximum imbalance one could expect to experience during the Shuttle Program.

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.

An Experiment on Repetitive Pulse Operation of Microwave Rocket

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

Oda, Yasuhisa; Shibata, Teppei; Komurasaki, Kimiya

2008-04-28

Microwave Rocket was operated with repetitive pulses. The microwave rocket model with forced breathing system was used. The pressure history in the thruster was measured and the thrust impulse was deduced. As a result, the impulse decreased at second pulse and impulses at latter pulses were constant. The dependence of the thrust performance on the partial filling rate of the thruster was compared to the thrust generation model based on the shock wave driven by microwave plasma. The experimental results showed good agreement to the predicted dependency.

Work Optimization Predicts Accretionary Faulting: An Integration of Physical and Numerical Experiments

NASA Astrophysics Data System (ADS)

McBeck, Jessica A.; Cooke, Michele L.; Herbert, Justin W.; Maillot, Bertrand; Souloumiac, Pauline

2017-09-01

We employ work optimization to predict the geometry of frontal thrusts at two stages of an evolving physical accretion experiment. Faults that produce the largest gains in efficiency, or change in external work per new fault area, ΔWext/ΔA, are considered most likely to develop. The predicted thrust geometry matches within 1 mm of the observed position and within a few degrees of the observed fault dip, for both the first forethrust and backthrust when the observed forethrust is active. The positions of the second backthrust and forethrust that produce >90% of the maximum ΔWext/ΔA also overlap the observed thrusts. The work optimal fault dips are within a few degrees of the fault dips that maximize the average Coulomb stress. Slip gradients along the detachment produce local elevated shear stresses and high strain energy density regions that promote thrust initiation near the detachment. The mechanical efficiency (Wext) of the system decreases at each of the two simulated stages of faulting and resembles the evolution of experimental force. The higher ΔWext/ΔA due to the development of the first pair relative to the second pair indicates that the development of new thrusts may lead to diminishing efficiency gains as the wedge evolves. The numerical estimates of work consumed by fault propagation overlap the range calculated from experimental force data and crustal faults. The integration of numerical and physical experiments provides a powerful approach that demonstrates the utility of work optimization to predict the development of faults.

Association Between Medicare Summary Star Ratings for Patient Experience and Clinical Outcomes in US Hospitals.

PubMed

Trzeciak, Stephen; Gaughan, John P; Bosire, Joshua; Mazzarelli, Anthony J

2016-03-01

In 2015, the Centers for Medicare and Medicaid Services (CMS) released new summary star ratings for US hospitals based on patient experience. We aimed to test the association between CMS patient experience star ratings and clinical outcomes. We analyzed risk-adjusted data for more than 3000 US hospitals from CMS Hospital Compare using linear regression. We found that better patient experience was associated with favorable clinical outcomes. Specifically, a higher number of stars for patient experience had a statistically significant association with lower rates of many in-hospital complications. A higher patient experience star rating also had a statistically significant association with lower rates of unplanned readmissions to the hospital within 30 days. Better patient experience according to the CMS star ratings is associated with favorable clinical outcomes. These results support the inclusion of patient experience data in the framework of how hospitals are paid for services.

Does CO trace H2 at high galactic latitude

NASA Technical Reports Server (NTRS)

Bazell, David; Blitz, L.; Desert, Francois-Xavier

1989-01-01

A CO survey of 342 Infrared Excess Clouds (IRECs) distributed uniformly across the sky is presented. Following comparison of the integrated CO brightness with the 100 micron infrared brightness B(sub 4) obtained from the IRAS data, evidence was found for a threshold in B(sub 4) of 4-5 MJy sr(exp -1) below which CO does not form. Evidence is also presented that the threshold effect can be seen within an individual cloud, providing evidence for a phase transition between atomic and molecular gas. While the main thrust was to examine the CO content of the IRECs, it was also attempted to detect CO toward a number of UV stars so that CO brightness could be correlated with direct measurements of H2 column density and E(B-V). Of the 26 observed stars CO was detected toward 6. It is consistent with the results obtained using infrared data.

Spacing of Imbricated Thrust Faults and the Strength of Thrust-Belts and Accretionary Wedges

NASA Astrophysics Data System (ADS)

Ito, G.; Regensburger, P. V.; Moore, G. F.

2017-12-01

The pattern of imbricated thrust blocks is a prominent characteristic of the large-scale structure of thrust-belts and accretionary wedges around the world. Mechanical models of these systems have a rich history from laboratory analogs, and more recently from computational simulations, most of which, qualitatively reproduce the regular patterns of imbricated thrusts seen in nature. Despite the prevalence of these patterns in nature and in models, our knowledge of what controls the spacing of the thrusts remains immature at best. We tackle this problem using a finite difference, particle-in-cell method that simulates visco-elastic-plastic deformation with a Mohr-Coulomb brittle failure criterion. The model simulates a horizontal base that moves toward a rigid vertical backstop, carrying with it an overlying layer of crust. The crustal layer has a greater frictional strength than the base, is cohesive, and is initially uniform in thickness. As the layer contracts, a series of thrust blocks immerge sequentially and form a wedge having a mean taper consistent with that predicted by a noncohesive, critical Coulomb wedge. The widths of the thrust blocks (or spacing between adjacent thrusts) are greatest at the front of the wedge, tend to decrease with continued contraction, and then tend toward a pseudo-steady, minimum width. Numerous experiments show that the characteristic spacing of thrusts increases with the brittle strength of the wedge material (cohesion + friction) and decreases with increasing basal friction for low (<8°) taper angles. These relations are consistent with predictions of the elastic stresses forward of the frontal thrust and at what distance the differential stress exceeds the brittle threshold to form a new frontal thrust. Hence the characteristic spacing of the thrusts across the whole wedge is largely inherited at the very front of the wedge. Our aim is to develop scaling laws that will illuminate the basic physical processes controlling systems, as well as allow researchers to use observations of thrust spacing as an independent constraint on the brittle strength of wedges as well as their bases.

Pressure and Thrust Measurements of a High-Frequency Pulsed Detonation Tube

NASA Technical Reports Server (NTRS)

Nguyen, N.; Cutler, A. D.

2008-01-01

This paper describes measurements of a small-scale, high-frequency pulsed detonation tube. The device utilized a mixture of H2 fuel and air, which was injected into the device at frequencies of up to 1200 Hz. Pulsed detonations were demonstrated in an 8-inch long combustion volume, at about 600 Hz, for the quarter wave mode of resonance. The primary objective of this experiment was to measure the generated thrust. A mean value of thrust was measured up to 6.0 lb, corresponding to H2 flow based specific impulse of 2970 s. This value is comparable to measurements in H2-fueled pulsed detonation engines (PDEs). The injection and detonation frequency for this new experimental case was much higher than typical PDEs, where frequencies are usually less than 100 Hz. The compact size of the device and high frequency of detonation yields a thrust-per-unit-volume of approximately 2.0 pounds per cubic inch, and compares favorably with other experiments, which typically have thrust-per-unit-volume of order 0.01 pound per cubic inch. This much higher volumetric efficiency results in a potentially much more practical device than the typical PDE, for a wide range of potential applications, including high-speed boundary layer separation control, for example in hypersonic engine inlets, and propulsion for small aircraft and missiles.

Rotor Hover Performance and Flowfield Measurements with Untwisted and Highly-Twisted Blades

NASA Technical Reports Server (NTRS)

Ramasamy, Manikandan; Gold, Nili P.; Bhagwat, Mahendra J.

2010-01-01

The flowfield and performance characteristics of highly-twisted blades were analyzed at various thrust conditions to improve the fundamental understanding relating the wake effects on rotor performance. Similar measurements made using untwisted blades served as the baseline case. Twisted blades are known to give better hover performance than untwisted blades at high thrust coefficients typical of those found in full-scale rotors. However, the present experiments were conducted at sufficiently low thrust (beginning from zero thrust), where the untwisted blades showed identical, if not better, performance when compared with the highly-twisted blades. The flowfield measurements showed some key wake differences between the two rotors, as well. These observations when combined with simple blade element momentum theory (also called annular disk momentum theory) helped further the understanding of rotor performance characteristics.

A rotor-aerodynamics-based wind estimation method using a quadrotor

NASA Astrophysics Data System (ADS)

Song, Yao; Luo, Bing; Meng, Qing-Hao

2018-02-01

Attempts to estimate horizontal wind by the quadrotor are reviewed. Wind estimations are realized by utilizing the quadrotor’s thrust change, which is caused by the wind’s effect on the rotors. The basis of the wind estimation method is the aerodynamic formula for the rotor’s thrust, which is verified and calibrated by experiments. A hardware-in-the-loop simulation (HILS) system was built as a testbed; its dynamic model and control structure are demonstrated. Verification experiments on the HILS system proved that the wind estimation method was effective.

Influence of the cage on friction torque in low loaded thrust ball bearing operating in dry conditions

NASA Astrophysics Data System (ADS)

Olaru, D.; Balan, M. R.; Tufescu, A.

2016-08-01

The authors investigated analytically and experimentally the friction torque in a modified thrust ball bearing operating at very low axial load in dry conditions by using only three balls and a cage. The experiments were conducted by using spin-down methodology. The results evidenced the influence of the sliding friction between the cage and the balls on the total friction torque. It was concluded that at very low loads the friction between cage and balls in a thrust ball bearing has an important contribution on total friction torque.

Space Storable Propellant Performance Gas/Liquid Like-Doublet Injector Characterization

NASA Technical Reports Server (NTRS)

Falk, A. Y.

1972-01-01

A 30-month applied research program was conducted, encompassing an analytical, design, and experimental effort to relate injector design parameters to simultaneous attainment of high performance and component (injector/thrust chamber) compatibility for gas/liquid space-storable propellants. The gas/liquid propellant combination selected for study was FLOX (82.6% F2)/ambient temperature gaseous methane. The injector pattern characterized was the like-(self)-impinging doublet. Program effort was apportioned into four basic technical tasks: injector and thrust chamber design, injector and thrust chamber fabrication, performance evaluation testing, and data evaluation and reporting. Analytical parametric combustion analyses and cold flow distribution and atomization experiments were conducted with injector segment models to support design of injector/thrust chamber combinations for hot fire evaluation. Hot fire tests were conducted to: (1) optimize performance of the injector core elements, and (2) provide design criteria for the outer zone elements so that injector/thrust chamber compatibility could be achieved with only minimal performance losses.

Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators

NASA Astrophysics Data System (ADS)

Ashpis, David E.; Laun, Matthew C.

2013-11-01

DBD plasma actuators generate a wall-jet that can be used for active flow control. We used an analytical balance to measure the thrust generated by the actuator, it is a common metric of its performance without external flow. We found that the measured force is afflicted by several problems; it drifts in time, not always repeatable, is unstable, and depends on the manner the voltage is applied. We report results of investigations of these issues. Tests were conducted on an actuator constructed of 1/4 inch thick high-density polyethylene (HDPE) dielectric with 100 mm long offset electrodes, with applied voltages up to 48 kV p-p and frequencies from 32 Hz to 2.5 kHz, and pure Sine and Trapezoidal waveforms. The relative humidity was in the range of 51-55%, corresponding to moisture range of 10,500 to13,000 ppm mass. Force readings were up to 500 mg, (approximately 50 mN/m). We found that the measured force is the net of the positive thrust generated by the wall-jet and an ``anti-thrust'' acting in the opposite direction. We propose a correction procedure that yields the plasma-generated thrust. The correction is based on voltage-dependent anti-thrust measured in the low frequency range of 20-40 Hz. We found that adjacent objects in a test setup affect the measured thrust, and verified it by comparing experiments with and without a metal enclosure, grounded and ungrounded. Uncorrected thrust varied by up to approximately +/-100%, and the corrected thrust variations were up to approximately 30%. Supported by NASA's FAP/Aerospace Sciences Project.

Experiments on high speed ejectors

NASA Technical Reports Server (NTRS)

Wu, J. J.

1986-01-01

Experimental studies were conducted to investigate the flow and the performance of thrust augmenting ejectors for flight Mach numbers in the range of 0.5 to 0.8, primary air stagnation pressures up to 107 psig (738 kPa), and primary air stagnation temperatures up to 1250 F (677 C). The experiment verified the existence of the second solution ejector flow, where the flow after complete mixing is supersonic. Thrust augmentation in excess of 1.2 was demonstrated for both hot and cold primary jets. The experimental ejector performed better than the corresponding theoretical optimal first solution ejector, where the mixed flow is subsonic. Further studies are required to realize the full potential of the second solution ejector. The research program was started by the Flight Dynamics Research Corporation (FDRC) to investigate the characteristic of a high speed ejector which augments thrust of a jet at high flight speeds.

Double salt décollements: Effect of pinch-out overlapping in experimental thrust wedges

NASA Astrophysics Data System (ADS)

Santolaria, P.; Vendeville, B.; Graveleau, F.; Casas, A.; Soto, R.

2013-12-01

The presence of one or more evaporitic horizons acting as detachment levels in fold-and-thrust belts is common. Numerous works have dealt with the analysis of the role played by basal detachments on the deformation style of fold-and-thrust belts, but less attention has been paid to the interaction between two décollements and strain transfer between them. In this study, 10 sand-silicone analogue experiments with two detachment levels and different stratigraphic pinch-out configurations were carried out: the basal décollement was located hinterlandwards, and the upper one was located forelandwards, with or without geographic underlap or overlap. These geometrical arrangements simulate evaporites deposited in foreland basins progressively involved in shortening. To analyze their influence on the geometry and kinematics of thrust wedges, we tested successively the following parameters: i) the amount of vertical overlapping between the two décollement pinch-outs, ii) the total amount of shortening, and iii) the geometry of the intermediate décollement (pinch-out line parallel or oblique with respect to the pinch-out line of the basal décollement). All experiments were quantitatively monitored by carrying DEM (Digital Elevation Models) and PIV (Particle Image Velocimetry) measurements. All models had a similar style: (i) an inner domain, characterized by a thicker sand cover, with three forward verging thrusts rooted in the basal décollement, (ii) an outer domain with thinner sand cover, whose deformation pattern was characterized by 2 to 6 structures detaching on the upper décollement and (iii) a 'step zone' located between the inner and outer domains having varying geometry and kinematics. In longer-lived models, structures were reworked and salt migration deformed the early emplaced folds and thrusts. Our experimental results point out that the amount of vertical overlapping between the two décollement pinch outs is a first order parameter that conditions not only the geometry and deformation of the 'step zone', but also the geometry and kinematics of the entire thrust wedge. Comparison with the foreland fold-and-thrust belt from the Southeastern Pyrenees, where deformation is transferred from the Triassic evaporites to Eocene-Oligocene evaporitic horizons deposited in front of the advancing Pyrenean thrust sheets, supports the experimental results and validates their interpretation.

Research in High Energy Physics

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

Wilson, Robert John; Toki, Walter; Harton, John

This report summarizes research performed within the Department of Energy Office of Science's Intensity Frontier and Cosmic Frontier High Energy Physics research subprograms during the period 2014-17. The major research thrusts in the Intensity Frontier involved two currently active neutrino experiments T2K and NOvA; participation in development for the new Short-Baseline Neutrino program at Fermilab (SBN), which will begin full operation within the next one to two years; and physics tools, analysis and detector prototyping for the future Deep Underground Neutrino Experiment (DUNE). The major research thrusts in the Cosmic Frontier involved the Pierre Auger Observatory and the Directional Recoilmore » Identification From Tracks (DRIFT) dark matter search experiment.« less

Effect of Cohesion Uncertainty of Granular Materials on the Kinematics of Scaled Models of Fold-and-Thrust Belts

NASA Astrophysics Data System (ADS)

Nilfouroushan, F.; Pysklywec, R.; Cruden, S.

2009-05-01

Cohesionless or very low cohesion granular materials are widely used in analogue/physical models to simulate brittle rocks in the upper crust. Selection of materials with appropriate cohesion values in such models is important for the simulation of the dynamics of brittle rock deformation in nature. Uncertainties in the magnitude of cohesion (due to measurement errors, extrapolations at low normal stresses, or model setup) in laboratory experiments can possibly result in misinterpretation of the styles and mechanisms of deformation in natural fold-and thrust belts. We ran a series of 2-D numerical models to investigate systematically the effect of cohesion uncertainties on the evolution of models of fold-and-thrust belts. The analyses employ SOPALE, a geodynamic code based on the arbitrary Lagrangian-Eulerian (ALE) finite element method. Similar to analogue models, the material properties of sand and transparent silicone (PDMS) are used to simulate brittle and viscous behaviors of upper crustal rocks. The suite of scaled brittle and brittle-viscous numerical experiments have the same initial geometry but the cohesion value of the brittle layers is increased systematically from 0 to 100 Pa. The stress and strain distribution in different sets of models with different cohesion values are compared and analyzed. The kinematics and geometry of thrust wedges including the location and number of foreland- and hinterland- verging thrust faults, pop-up structures, tapers and topography are also explored and their sensitivity to cohesion value is discussed.

Initial Results of a Far-Ultraviolet Spectroscopic Survey of Nearby Star-forming Galaxies with the Cosmic Origins Spectrograph

NASA Astrophysics Data System (ADS)

Redwine, Keith; McCandliss, Stephan R.; Wofford, Aida; Leitherer, Claus; Heckman, Timothy M.; France, Kevin; Fleming, Brian

2017-01-01

We present initial results for the HST Cycle 22 proposal 13761. We proposed to observe 75 target star-forming galaxies at a redshift 0.02 < z < 0.24 in the G140L mode of COS, spanning a bandpass of 1100 < λ < 2400 angstroms, and have thus far observed 34 of them. The main thrust of this project is to provide a previously unavailable survey of star-forming galaxies in this redshift range, allowing investigation into the factors that determine the Lyman-alpha emission at these low redshifts. We have begun a statistical analysis of the relationship between Lyman-alpha emission and the morphologies of the galaxies, such as absorption line strengths of other species, including various ionization states of oxygen, silicon, and other species to probe intrinsic properties of the emitting galaxy, such as metallicity, the gas-to-dust ratio, and local velocity fields. We have acquired a very rich dataset, with enough samples to try to answer a variety of open questions regarding the far-ultraviolet spectra of bright Lyman-alpha emitters. This work is supported by a NASA Grant HST-GO-13761 to the Johns Hopkins University.

Accretion shocks in the laboratory: Design of an experiment to study star formation

DOE PAGES

Young, Rachel P.; Kuranz, C. C.; Drake, R. P.; ...

2017-02-13

Here, we present the design of a laboratory-astrophysics experiment to study magnetospheric accretion relevant to young, pre-main-sequence stars. Spectra of young stars show evidence of hotspots created when streams of accreting material impact the surface of the star and create shocks. The structures that form during this process are poorly understood, as the surfaces of young stars cannot be spatially resolved. Our experiment would create a scaled "accretion shock" at a major (several kJ) laser facility. The experiment drives a plasma jet (the "accretion stream") into a solid block (the "stellar surface"), in the presence of a parallel magnetic fieldmore » analogous to the star's local field.« less

Free-choice family learning experiences at informal astronomy observing events

NASA Astrophysics Data System (ADS)

Wenger, Matthew C.

This qualitative study is an exploratory look at family experiences at night time telescope observing events, often called star parties. Four families participated in this study which looked at their expectations, experiences and agendas as well as the roles that identity and family culture played in the negotiation of meaning. Two families who had prior experience with attending star parties were recruited ahead of time and two other families who were first time visitors were recruited on-site at the observing event. Data were collected at two star parties. At each event, one experienced family was paired with an on-site family for the purposes of facilitating conversations about expectations and prior experiences. The results of this study showed that learning is constantly occurring among families, and that star parties and family culture were mediational means for making meaning. Expectations and agendas were found to affect the families' star party experiences and differences were observed between the expectations and experiences of families based on their prior experiences with star parties. These data also showed that family members are actively negotiating their individual and family identities. These families use their cultural history together to make sense of their star party experiences; however, the meaning that families were negotiating was often focused more on developing family and individual identity rather than science content. The families in this study used the star party context as a way to connect with each other, to make sense of their prior experiences, and as raw material for making sense of future experiences.

A Computational Study of a New Dual Throat Fluidic Thrust Vectoring Nozzle Concept

NASA Technical Reports Server (NTRS)

Deere, Karen A.; Berrier, Bobby L.; Flamm, Jeffrey D.; Johnson, Stuart K.

2005-01-01

A computational investigation of a two-dimensional nozzle was completed to assess the use of fluidic injection to manipulate flow separation and cause thrust vectoring of the primary jet thrust. The nozzle was designed with a recessed cavity to enhance the throat shifting method of fluidic thrust vectoring. Several design cycles with the structured-grid, computational fluid dynamics code PAB3D and with experiments in the NASA Langley Research Center Jet Exit Test Facility have been completed to guide the nozzle design and analyze performance. This paper presents computational results on potential design improvements for best experimental configuration tested to date. Nozzle design variables included cavity divergence angle, cavity convergence angle and upstream throat height. Pulsed fluidic injection was also investigated for its ability to decrease mass flow requirements. Internal nozzle performance (wind-off conditions) and thrust vector angles were computed for several configurations over a range of nozzle pressure ratios from 2 to 7, with the fluidic injection flow rate equal to 3 percent of the primary flow rate. Computational results indicate that increasing cavity divergence angle beyond 10 is detrimental to thrust vectoring efficiency, while increasing cavity convergence angle from 20 to 30 improves thrust vectoring efficiency at nozzle pressure ratios greater than 2, albeit at the expense of discharge coefficient. Pulsed injection was no more efficient than steady injection for the Dual Throat Nozzle concept.

Developing stochastic model of thrust and flight dynamics for small UAVs

NASA Astrophysics Data System (ADS)

Tjhai, Chandra

This thesis presents a stochastic thrust model and aerodynamic model for small propeller driven UAVs whose power plant is a small electric motor. First a model which relates thrust generated by a small propeller driven electric motor as a function of throttle setting and commanded engine RPM is developed. A perturbation of this model is then used to relate the uncertainty in throttle and engine RPM commanded to the error in the predicted thrust. Such a stochastic model is indispensable in the design of state estimation and control systems for UAVs where the performance requirements of the systems are specied in stochastic terms. It is shown that thrust prediction models for small UAVs are not a simple, explicit functions relating throttle input and RPM command to thrust generated. Rather they are non-linear, iterative procedures which depend on a geometric description of the propeller and mathematical model of the motor. A detailed derivation of the iterative procedure is presented and the impact of errors which arise from inaccurate propeller and motor descriptions are discussed. Validation results from a series of wind tunnel tests are presented. The results show a favorable statistical agreement between the thrust uncertainty predicted by the model and the errors measured in the wind tunnel. The uncertainty model of aircraft aerodynamic coefficients developed based on wind tunnel experiment will be discussed at the end of this thesis.

Optimal trajectories for solar bow shock mission

NASA Astrophysics Data System (ADS)

Pizzurro, S.; Circi, C.

2012-11-01

This paper deals a Solar Bow Shock mission, a phenomenon of interaction between the solar wind and the interstellar medium, due to the relative motion of our star with respect to the enormous interstellar matter cloud that contains it. This phenomenon occurs at boundary of the solar system (200 AU), and it is preferable a mission in situ that could examine in detail what actually happens on-the-spot, to understand its effect on the planets of the solar system. Voyager 1 & 2 reached the area where the phenomenon takes place after 30 years. The target is to arrive there optimizing both the transfer time, and the propellant mass consumption. Therefore, the trajectory will be optimized using different propulsion systems and appropriate flyby sequences.. The approach techniques that will be used foresee executions of impulsive or ballistic gravity assists with the utilisation of high thrust engine only, or low thrust engine only, or both engines in two different phases of the mission. By comparing all the solutions obtained imposing different initial conditions the optimal trajectory to arrive at Solar Bow Shock is presented.

X-31 quasi-tailless flight demonstration

NASA Technical Reports Server (NTRS)

Huber, Peter; Schellenger, Harvey G.

1994-01-01

The primary objective of the quasi-tailless flight demonstration is to demonstrate the feasibility of using thrust vectoring for directional control of an unstable aircraft. By using this low-cost, low-risk approach it is possible to get information about required thrust vector control power and deflection rates from an inflight experiment as well as insight in low-power thrust vectoring issues. The quasi-tailless flight demonstration series with the X-31 began in March 1994. The demonstration flight condition was Mach 1.2 at 37,500 feet. A series of basic flying quality maneuvers, doublets, bank to bank rolls, and wind-up-turns have been performed with a simulated 100% vertical tail reduction. Flight test and supporting simulation demonstrated that the quasi-tailless approach is effective in representing the reduced stability of tailless configurations. The flights also demonstrated that thrust vectoring could be effectively used to stabilize a directionally unstable configuration and provide control power for maneuver coordination.

Magnet pole shape design for reduction of thrust ripple of slotless permanent magnet linear synchronous motor with arc-shaped magnets considering end-effect based on analytical method

NASA Astrophysics Data System (ADS)

Shin, Kyung-Hun; Park, Hyung-Il; Kim, Kwan-Ho; Jang, Seok-Myeong; Choi, Jang-Young

2017-05-01

The shape of the magnet is essential to the performance of a slotless permanent magnet linear synchronous machine (PMLSM) because it is directly related to desirable machine performance. This paper presents a reduction in the thrust ripple of a PMLSM through the use of arc-shaped magnets based on electromagnetic field theory. The magnetic field solutions were obtained by considering end effect using a magnetic vector potential and two-dimensional Cartesian coordinate system. The analytical solution of each subdomain (PM, air-gap, coil, and end region) is derived, and the field solution is obtained by applying the boundary and interface conditions between the subdomains. In particular, an analytical method was derived for the instantaneous thrust and thrust ripple reduction of a PMLSM with arc-shaped magnets. In order to demonstrate the validity of the analytical results, the back electromotive force results of a finite element analysis and experiment on the manufactured prototype model were compared. The optimal point for thrust ripple minimization is suggested.

Performance characterization of a permanent-magnet helicon plasma thruster

NASA Astrophysics Data System (ADS)

Takahashi, Kazunori; Charles, Christine; Boswell, Rod

2012-10-01

Helicon plasma thrusters operated at a few kWs of rf power is an active area of an international research. Recent experiments have clarified part of the thrust-generation mechanisms. Thrust components which have been identified include an electron pressure inside the source region and a Lorentz force due to an electron diamagnetic drift current and a radial component of the applied magnetic field. The use of permanent magnets (PMs) instead of solenoids is one of the solutions for improving the thruster efficiency because it does not require electricity for the magnetic nozzle formation. Here the thrust imparted from a permanent-magnet helicon plasma thruster is directly measured using a pendulum thrust balance. The source consists of permanent magnet (PM) arrays, a double turn rf loop antenna powered by a 13.56 MHz rf generator and a glass source tube. The PM arrays provide a magnetic nozzle near the open exit of the source and two configurations, which have maximum field strengths of about 100 and 270 G, are tested. A thrust of 15 mN, specific impulse of 2000 sec and a thrust efficiency of 8 percent are presently obtained for 2 kW of input power, 24 sccm flow rate of argon and the stronger magnetic field configuration.

Hydrodynamic thrust generation and power consumption investigations for piezoelectric fins with different aspect ratios

NASA Astrophysics Data System (ADS)

Shahab, S.; Tan, D.; Erturk, A.

2015-12-01

Bio-inspired hydrodynamic thrust generation using piezoelectric transduction has recently been explored using Macro-Fiber Composite (MFC) actuators. The MFC technology strikes a balance between the actuation force and structural deformation levels for effective swimming performance, and additionally offers geometric scalability, silent operation, and ease of fabrication. Recently we have shown that mean thrust levels comparable to biological fish of similar size can be achieved using MFC fins. The present work investigates the effect of length-to-width (L/b) aspect ratio on the hydrodynamic thrust generation performance of MFC cantilever fins by accounting for the power consumption level. It is known that the hydrodynamic inertia and drag coefficients are controlled by the aspect ratio especially for L/b< 5. The three MFC bimorph fins explored in this work have the aspect ratios of 2.1, 3.9, and 5.4. A nonlinear electrohydroelastic model is employed to extract the inertia and drag coefficients from the vibration response to harmonic actuation for the first bending mode. Experiments are then conducted for various actuation voltage levels to quantify the mean thrust resultant and power consumption levels for different aspect ratios. Variation of the thrust coefficient of the MFC bimorph fins with changing aspect ratio is also semi-empirically modeled and presented.

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.

Performance Assessment of a Large Scale Pulsejet- Driven Ejector System

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.; Litke, Paul J.; Schauer, Frederick R.; Bradley, Royce P.; Hoke, John L.

2006-01-01

Unsteady thrust augmentation was measured on a large scale driver/ejector system. A 72 in. long, 6.5 in. diameter, 100 lb(sub f) pulsejet was tested with a series of straight, cylindrical ejectors of varying length, and diameter. A tapered ejector configuration of varying length was also tested. The objectives of the testing were to determine the dimensions of the ejectors which maximize thrust augmentation, and to compare the dimensions and augmentation levels so obtained with those of other, similarly maximized, but smaller scale systems on which much of the recent unsteady ejector thrust augmentation studies have been performed. An augmentation level of 1.71 was achieved with the cylindrical ejector configuration and 1.81 with the tapered ejector configuration. These levels are consistent with, but slightly lower than the highest levels achieved with the smaller systems. The ejector diameter yielding maximum augmentation was 2.46 times the diameter of the pulsejet. This ratio closely matches those of the small scale experiments. For the straight ejector, the length yielding maximum augmentation was 10 times the diameter of the pulsejet. This was also nearly the same as the small scale experiments. Testing procedures are described, as are the parametric variations in ejector geometry. Results are discussed in terms of their implications for general scaling of pulsed thrust ejector systems

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.

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

Kinematics and Seismotectonics of the Montello Thrust Fault (Southeastern Alps, Italy) Revealed by Local GPS and Seismic Networks

NASA Astrophysics Data System (ADS)

Serpelloni, E.; Anderlini, L.; Cavaliere, A.; Danesi, S.; Pondrelli, S.; Salimbeni, S.; Danecek, P.; Massa, M.; Lovati, S.

2014-12-01

The southern Alps fold-and-thrust belt (FTB) in northern Italy is a tectonically active area accommodating large part of the ~N-S Adria-Eurasia plate convergence, that in the southeastern Alps ranges from 1.5 to 2.5 mm/yr, as constrained by a geodetically defined rotation pole. Because of the high seismic hazard of northeastern Italy, the area is well monitored at a regional scale by seismic and GPS networks. However, more localized seismotectonic and kinematic features, at the scale of the fault segments, are not yet resolved, limiting our knowledge about the seismic potential of the different fault segments belonging to the southeastern Alps FTB. Here we present the results obtained from the analysis of data collected during local seismic and geodetic experiments conducted installing denser geophysical networks across the Montello-Bassano-Belluno system, a segment of the FTB that is presently characterized by a lower sismicity rate with respect to the surrounding domains. The Montello anticline, which is the southernmost tectonic features of the southeastern Alps FTB (located ~15 km south of the mountain front), is a nice example of growing anticline associated with a blind thrust fault. However, how the Adria-Alps convergence is partitioned across the FTB and the seismic potential of the Montello thrust (the area has been struck by a Mw~6.5 in 1695 but the causative fault is still largely debated) remained still unresolved. The new, denser, GPS data show that this area is undergoing among the highest geodetic deformation rates of the entire south Alpine chain, with a steep velocity gradient across the Montello anticline. The earthquakes recorded during the experiment, precisely relocated with double difference methods, and the new earthquake focal mechanisms well correlate with available information about sub-surface geological structures and highlight the seismotectonic activity of the Montello thrust fault. We model the GPS velocities using elastic dislocations embedded in a kinematic block model approach, which suggest that the Montello thrust fault is weakly coupled with respect to surrounding segments of the southernmost thrust system. Future works will include the integration of InSAR data and the densification/improvement of the geodetic infrastructure.

False star detection and isolation during star tracking based on improved chi-square tests.

PubMed

Zhang, Hao; Niu, Yanxiong; Lu, Jiazhen; Yang, Yanqiang; Su, Guohua

2017-08-01

The star sensor is a precise attitude measurement device for a spacecraft. Star tracking is the main and key working mode for a star sensor. However, during star tracking, false stars become an inevitable interference for star sensor applications, which may result in declined measurement accuracy. A false star detection and isolation algorithm in star tracking based on improved chi-square tests is proposed in this paper. Two estimations are established based on a Kalman filter and a priori information, respectively. The false star detection is operated through adopting the global state chi-square test in a Kalman filter. The false star isolation is achieved using a local state chi-square test. Semi-physical experiments under different trajectories with various false stars are designed for verification. Experiment results show that various false stars can be detected and isolated from navigation stars during star tracking, and the attitude measurement accuracy is hardly influenced by false stars. The proposed algorithm is proved to have an excellent performance in terms of speed, stability, and robustness.

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.

Demand thrust pumped propulsion with automatic warm gas valving

NASA Astrophysics Data System (ADS)

Whitehead, J. C.

1992-06-01

Operation of a thrust-on-demand, monopropellant rocket propulsion system which uses lightweight low-pressure tankage, free-piston pumps, and a small high-pressure thrust chamber, is explained. The pump intake-exhaust valves use warm gas pneumatic signals to ensure that two reciprocating pumps are alternately pressurized, with overlap during switchover to permit uninterrupted propellant flow. Experiments demonstrate that the miniature pumps operate at any speed depending on downstream demand, and can deliver nearly their own mass in hydrazine per second, at 7 MPa (1000 psi). The valves, which use the alternating layers of metal and graphite to mitigate the effects of differential thermal expansion, have been warm-gas tested for thousands of cycles. For biopropellant operation, a pair of reciprocating oxidizer pumps would be slaved to the fuel pumps' pneumatic oscillator, to provide for pulsed or continuous demand-driven flow of both liquids. Mass ratios and thrust-to-weight ratios of demand-thrust pumped propulsion systems compare quite favorably to those of pressure-fed and turbo-pumped systems. Due to the relatively high densities of storable propellants, liquid mass fractions greater than 0.95 are attainable with these novel pumps, with thrust/weight ratios above 10. The high performance potential of small propulsion systems which use reciprocating pumps suggests that this technology can significantly increase the capability of many types of small spacecraft.

Scaling of Performance in Liquid Propellant Rocket Engine Combustors

NASA Technical Reports Server (NTRS)

Hulka, James

2008-01-01

The objectives are: a) Re-introduce to you the concept of scaling; b) Describe the scaling research conducted in the 1950s and early 1960s, and present some of their conclusions; c) Narrow the focus to scaling for performance of combustion devices for liquid propellant rocket engines; and d) Present some results of subscale to full-scale performance from historical programs. Scaling is "The ability to develop new combustion devices with predictable performance on the basis of test experience with old devices." Scaling can be used to develop combustion devices of any thrust size from any thrust size. Scaling is applied mostly to increase thrust. Objective is to use scaling as a development tool. - Move injector design from an "art" to a "science"

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.

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

Characterization of in-flight performance of ion propulsion systems

NASA Astrophysics Data System (ADS)

Sovey, James S.; Rawlin, Vincent K.

1993-06-01

In-flight measurements of ion propulsion performance, ground test calibrations, and diagnostic performance measurements were reviewed. It was found that accelerometers provided the most accurate in-flight thrust measurements compared with four other methods that were surveyed. An experiment has also demonstrated that pre-flight alignment of the thrust vector was sufficiently accurate so that gimbal adjustments and use of attitude control thrusters were not required to counter disturbance torques caused by thrust vector misalignment. The effects of facility background pressure, facility enhanced charge-exchange reactions, and contamination on ground-based performance measurements are also discussed. Vacuum facility pressures for inert-gas ion thruster life tests and flight qualification tests will have to be less than 2 mPa to ensure accurate performance measurements.

Characterization of in-flight performance of ion propulsion systems

NASA Technical Reports Server (NTRS)

Sovey, James S.; Rawlin, Vincent K.

1993-01-01

In-flight measurements of ion propulsion performance, ground test calibrations, and diagnostic performance measurements were reviewed. It was found that accelerometers provided the most accurate in-flight thrust measurements compared with four other methods that were surveyed. An experiment has also demonstrated that pre-flight alignment of the thrust vector was sufficiently accurate so that gimbal adjustments and use of attitude control thrusters were not required to counter disturbance torques caused by thrust vector misalignment. The effects of facility background pressure, facility enhanced charge-exchange reactions, and contamination on ground-based performance measurements are also discussed. Vacuum facility pressures for inert-gas ion thruster life tests and flight qualification tests will have to be less than 2 mPa to ensure accurate performance measurements.

The 90-day report for SL4 experiment S019: UV stellar astronomy

NASA Technical Reports Server (NTRS)

1974-01-01

The use of Experiment S019 to obtain moderate dispersion stellar spectra extending down to 1300A with sufficient spectral resolution to permit the study of ultraviolet (UV) line spectra and of spectral energy distributions of early-type stars is studied. Data obtained from this experiment should be of sufficient accuracy to permit detailed physical analysis of individual stars and nebulae, but an even more basic consideration is the expectation of obtaining spectra of a sufficient number of stars so that a statistically meaningful survey may be made of the UV spectra of a wide variety of star types. These should include all luminosity classes of spectral types O, B and A, as well as peculiar stars such as Wolf-Rayet stars and Ap or Am stars. An attempt was also made to obtain, in the no-prism mode, low dispersion UV spectra in a number of Milky Way star fields and in nearby galaxies.

Modeling the evolution of a ramp-flat-ramp thrust system: A geological application of DynEarthSol2D

NASA Astrophysics Data System (ADS)

Feng, L.; Choi, E.; Bartholomew, M. J.

2013-12-01

DynEarthSol2D (available at http://bitbucket.org/tan2/dynearthsol2) is a robust, adaptive, two-dimensional finite element code that solves the momentum balance and the heat equation in Lagrangian form using unstructured meshes. Verified in a number of benchmark problems, this solver uses contingent mesh adaptivity in places where shear strain is focused (localization) and a conservative mapping assisted by marker particles to preserve phase and facies boundaries during remeshing. We apply this cutting-edge geodynamic modeling tool to the evolution of a thrust fault with a ramp-flat-ramp geometry. The overall geometry of the fault is constrained by observations in the northern part of the southern Appalachian fold and thrust belt. Brittle crust is treated as a Mohr-Coulomb plastic material. The thrust fault is a zone of a finite thickness but has a lower cohesion and friction angle than its surrounding rocks. When an intervening flat separates two distinct sequential ramps crossing different stratigraphic intervals, the thrust system will experience more complex deformations than those from a single thrust fault ramp. The resultant deformations associated with sequential ramps would exhibit a spectrum of styles, of which two end members correspond to ';overprinting' and ';interference'. Reproducing these end-member styles as well as intermediate ones, our models show that the relative importance of overprinting versus interference is a sensitive function of initial fault geometry and hanging wall displacement. We further present stress and strain histories extracted from the models. If clearly distinguishable, they will guide the interpretation of field observations on thrust faults.

Late extension in compressional wedges above a weak, viscous décollement: results from analogue modeling

NASA Astrophysics Data System (ADS)

Borderie, Sandra; Vendeville, Bruno C.; Graveleau, Fabien; Witt, César

2016-04-01

Extension during convergence is a structural process commonly encountered in different geodynamic settings, such as accretionary wedges subjected to tectonic erosion, or mountain belts undergoing post-orogenic collapse. This has been investigated with experimental models at the scale of doubly-vergent wedges (Haq and Davis 2008; Bonini et al. 2000, Buck and Sokoutis 1994) but not thoroughly at the scale of fold-and-thrust belts. During an experimental investigation carried out on the behavior of segmented fold-and-thrust belts induced by stratigraphic inheritance in the foreland series (Borderie et al., EGU this session), unexpected shallow normal faulting occurred. The models comprised one basal frictional décollement (glass microbeads) and one upper viscous décollement embedded in the cover (silicone polymer). Extension took place during the late stages of the experiments and it was localized at the transition zone between the rear domain of the wedge and the frontal fold-and-thrust belt that detached on the upper viscous décollement. Normal faults strike parallel to the compressional structures and mainly dip toward the foreland. They root in the viscous décollement. Through a series of parametrized experiments dedicated to constrain the timing of formation of these extensional structures, we could evidence that these normal faults appear once the bulk shortening in the rear domain has created enough uplift of the internal zone by antiformal stacking and enough forelandward tilting of the upper viscous décollement. These two latter mechanisms are direct consequences of the whole wedge dynamics that links the thrust fault dynamics in the upper shallow sedimentary sequence and the thrust dynamics of the deep subsalt basement. The occurrence of this extension depends on the initial position of the upper viscous décollement and notably the position of the internal pinchout relative to the position of the backstop. Additional tests have also demonstrated that this extension is prevented by surface processes and notably sedimentation. We compare our experimental findings with natural examples of extensional features in various fold-and-thrust belts and accretionary features across the world (e.g. the Mediterranean ridge). References: Bonini, Marco, Dimitrios Sokoutis, Genene Mulugeta, and Emmanouil Katrivanos. 2000. "Modelling Hanging Wall Accommodation above Rigid Thrust Ramps." Journal of Structural Geology 22 (8): 1165-79. Borderie, Sandra, Fabien Graveleau, Cesar Witt and Bruno C. Vendeville. 2016. "Analogue modeling of 3-D structural segmentation in fold-and-thrust belts: interactions between frictional and viscous provinces in foreland basins." Gephys. Res. Abstr., 18, EGU2016-Vienne. Buck, W Roger, and Dimitrios Sokoutis. 1994. "Analogue Model of Gravitational Collapse and Surface Extension during Continental Convergence." Nature 369: 737-40. Haq, Saad SB, and Dan M. Davis. 2008. "Extension during Active Collision in Thin-Skinned Wedges: Insights from Laboratory Experiments." Geology 36 (6): 475-78.

Mach-Effect thruster model

NASA Astrophysics Data System (ADS)

Tajmar, M.

2017-12-01

The Mach-Effect thruster is a propellantless propulsion concept that has been in development by J.F. Woodward for more than two decades. It consists of a piezo stack that produces mass fluctuations, which in turn can lead to net time-averaged thrusts. So far, thrust predictions had to use an efficiency factor to explain some two orders of magnitude discrepancy between model and observations. Here, a detailed 1D analytical model is presented that takes piezo material parameters and geometry dimensions into account leading to correct thrust predictions in line with experimental measurements. Scaling laws can now be derived to improve thrust range and efficiency. An important difference in this study is that only the mechanical power developed by the piezo stack is considered to be responsible for the mass fluctuations, whereas prior works focused on the electrical energy into the system. This may explain why some previous designs did not work as expected. The good match between this new mathematical formulation and experiments should boost confidence in the Mach effect thruster concept to stimulate further developments.

An Experimental/Modeling Study of Jet Attachment during Counterflow Thrust Vectoring

NASA Technical Reports Server (NTRS)

Strykowski, Paul J.

1997-01-01

Recent studies have shown the applicability of vectoring rectangular jets using asymmetrically applied counterflow in the presence of a short collar. This novel concept has applications in the aerospace industry where counterflow can be used to vector the thrust of a jet's exhaust, shortening take-off and landing distances and enhancing in-flight maneuverability of the aircraft. Counterflow thrust vectoring, 'CFTV' is desirable due to its fast time response, low thrust loss, and absence of moving parts. However, implementation of a CFTV system is only possible if bistable jet attachment can be prevented. This can be achieved by properly designing the geometry of the collar. An analytical model is developed herein to predict the conditions under which a two-dimensional jet will attach to an offset curved wall. Results from this model are then compared with experiment; for various jet exit Mach numbers, collar offset distances, and radii of curvature. Their excellent correlation permits use of the model as a tool for designing a CFTV system.

Noise, Turbulence, and Thrust of Subsonic Free Jets from Lobed Nozzles

NASA Technical Reports Server (NTRS)

Zaman, K. B. M. Q.; Wang, F. Y.

2002-01-01

A study of noise benefit, vis-a-vis thrust penalty, and its correlation to turbulence intensities was conducted for free jets issuing from lobed nozzles. Four convergent nozzles with constant exit area were used in the experiments. Three of these were of rectangular lobed configuration having six, ten and fourteen lobes; the fourth was a circular nozzle. Increasing the number of lobes resulted in a progressive reduction in the turbulence intensities as well as in the overall radiated noise. The noise reduction was pronounced at the low frequency end of the spectrum. However, there was an increase in the high frequency noise that rendered the overall benefit less attractive when compared on a scaled-up A-weighted basis. A reduction in noise was accompanied by a commensurate reduction in the turbulent kinetic energy in the flow field. As expected, increasing the number of lobes involved progressive reduction in the thrust coefficient. Among the cases studied, the six-lobed nozzle had the optimum reduction in turbulence and noise with the least thrust penalty.

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.

Momentum and Heat Flux Measurements in the Exhaust of VASIMR using Helium Propellant

NASA Technical Reports Server (NTRS)

Chavers, D. Gregory; Chang-Diaz, Franklin R.; Irvine, Claude; Squire, Jared P.

2003-01-01

Interplanetary travel requires propulsion systems that can provide high specific impulse (Isp), while also having sufficient thrust to rapidly accelerate large payloads. One such propulsion system is the Variable Specific Impulse Magneto-plasma Rocket (VASIMR), which creates, heats, and ejects plasma to provide variable thrust and Isp, designed to optimally meet the mission requirements. The fraction of the total energy invested in creating the plasma, as compared to the plasma's total kinetic energy, is an important factor in determining the overall system efficiency. In VASIMR, this 'frozen flow loss' is appreciable when at high thrust, but negligible at high Isp. The loss applies to other electric thrusters as well. If some of this energy could be recovered through recombination processes, and reinjected as neutral kinetic energy, the efficiency of VASIMR, in its low Isp/high thrust mode may be improved. An experiment is being conducted to investigate the possibility of recovering some of the energy used to create the plasma by studying the flow characteristics of the charged and neutral particles in the exhaust of the thruster. This paper will cover the measurements of momentum flux and heat flux in the exhaust of the VASIMR test facility using helium as the propellant where the heat flux is comprised of both kinetic and plasma recombination energy. The flux measurements also assist in diagnosing and verifying the plasma conditions in the existing experiment.

Predicting orogenic wedge styles as a function of analogue erosion law and material softening

NASA Astrophysics Data System (ADS)

Mary, Baptiste C. L.; Maillot, Bertrand; Leroy, Yves M.

2013-10-01

The evolution of a compressive frictional wedge on a weak, frictional and planar décollement, subjected to frontal accretion, is predicted with a two step method called sequential limit analysis. The first step consists in finding, with the kinematic approach of limit analysis, the length of the active décollement and the dips of the emerging ramp and of the conjugate shear plane composing the emerging thrust fold. The second step leads to a modification of the geometry, first, because of the thrust fold development due to compression and, second, because of erosion. Erosion consists in removing periodically any material above a fictitious line at a selected slope, as done in analogue experiments. This application of sequential limit analysis generalizes the critical Coulomb wedge theory since it follows the internal deformation development. With constant frictional properties, the deformation is mostly diffuse, a succession of thrust folds being activated so that the topographic slope reaches exactly the theoretical, critical value. Frictional weakening on the ramps results in a deformation style composed of thrust sheets and horses. Applying an erosion slope at the critical topographic value leads to exhumation in the frontal, central, or rear region of the wedge depending on the erosion period and the weakening. Erosion at slopes slightly above or below the critical value results in exhumation toward the foreland or the hinterland, respectively, regardless of the erosion period. Exhumation is associated with duplexes, imbricate fans, antiformal stacks, and major backthrusting. Comparisons with sandbox experiments confirm that the thickness, dips, vergence, and exhumation of thrust sheets can be reproduced with friction and erosion parameters within realistic ranges of values.

Skylab

NASA Image and Video Library

1970-01-01

This photograph shows a telescopic camera for ultraviolet star photography for Skylab's Ultraviolet Panorama experiment (S183) placed in the Skylab airlock. The S183 experiment was designed to obtain ultraviolet photographs, at three wavelengths, of hot stars, clusters of stars, large stellar clouds in the Milky Way, and nuclei of other galaxies. The Marshall Space Flight Center had program responsibility for the development of Skylab hardware and experiments.

Skylab

NASA Image and Video Library

1972-01-01

This photograph describes details of the telescopic camera for ultraviolet star photography for Skylab's Ultraviolet Panorama experiment (S183) placed in the Skylab airlock. The S183 experiment was designed to obtain ultraviolet photographs at three wavelengths of hot stars, clusters of stars, large stellar clouds in the Milky Way, and nuclei of other galaxies. The Marshall Space Flight Center had program responsibility for the development of Skylab hardware and experiments.

Aerodynamic performance of a fan stage utilizing variable inlet guide vanes (VIGV's) for thrust modulation. [subsonic V/STOL aircraft

NASA Technical Reports Server (NTRS)

Woollett, R. R.

1983-01-01

An experimental research program was conducted in the Lewis Research Center's 9 x 15-foot (2.74 x 4.57 m) low speed wind tunnel to evaluate the aerodynamic performance of an inlet and fan system with variable inlet guide vanes (VIGVs) for use on a subsonic V/STOL aircraft. At high VIGV blade angles (lower weight flow and thrust levels), the fan stage was stalled over a major portion of its radius. In spite of the stall, fan blade stresses only exceeded the limits at the most extreme flow conditions. It was found that inlet flow separation does not necessarily lead to poor inlet performance or adverse fan operating conditions. Generally speaking, separated inlet flow did not adversely affect the fan blade stress levels. There were some cases, however, at high VIGV angles and high inlet angles-of-attack where excessive blade stress levels were encountered. An evaluation term made up of the product of the distortion parameter, K alpha, the weight flow and the fan pressure ratio minus one, was found to correlate quite well with the observed blade stress results. Previously announced in STAR as N83-27957

Effect of applied force and blade speed on histopathology of bone during resection by sagittal saw.

PubMed

James, Thomas P; Chang, Gerard; Micucci, Steven; Sagar, Amrit; Smith, Eric L; Cassidy, Charles

2014-03-01

A sagittal saw is commonly used for resection of bone during joint replacement surgery. During sawing, heat is generated that can lead to an increase in temperature at the resected surface. The aim of this study was to determine the effect of applied thrust force and blade speed on generating heat. The effect of these factors and their interactions on cutting temperature and bone health were investigated with a full factorial Design of Experiments approach for two levels of thrust force, 15 N and 30 N, and for two levels of blade oscillation rate, 12,000 and 18,000 cycles per minute (cpm). In addition, a preliminary study was conducted to eliminate blade wear as a confounding factor. A custom sawing fixture was used to crosscut samples of fresh bovine cortical bone while temperature in the bone was measured by thermocouple (n=40), followed by measurements of the depth of thermal necrosis by histopathological analysis (n=200). An analysis of variance was used to determine the significance of the factor effects on necrotic depth as evidenced by empty lacunae. Both thrust force and blade speed demonstrated a statistically significant effect on the depth of osteonecrosis (p<0.05), while the interaction of thrust force with blade speed was not significant (p=0.22). The minimum necrotic depth observed was 0.50mm, corresponding to a higher level of force and blade speed (30 N, 18,000 cpm). Under these conditions, a maximum temperature of 93°C was measured at 0.3mm from the kerf. With a decrease in both thrust force and blade speed (15N, 12,000 cpm), the temperature in the bone increased to 109°C, corresponding to a nearly 50% increase in depth of the necrotic zone to 0.74 mm. A predictive equation for necrotic depth in terms of thrust force and blade speed was determined through regression analysis and validated by experiment. The histology results imply that an increase in applied thrust force is more effective in reducing the depth of thermal damage to surrounding bone than an increase in blade speed. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Modelling the Deformation Front of a Fold-Thrust Belt: the Effect of an Upper Detachment Horizon

NASA Astrophysics Data System (ADS)

Burberry, C. M.; Koyi, H.; Nilfouroushan, F.; Cosgrove, J. W.

2008-12-01

Structures found at the deformation fronts of fold-thrust belts are variable in type, geometry and spatial organisation, as can be demonstrated from comparisons between structures in the Zagros Fold-Thrust Belt, Iran and the Sawtooth Range, Montana. A range of influencing factors has been suggested to account for this variation, including the mechanical properties and distribution of any detachment horizons within the cover rock succession. A series of analogue models was designed to test this hypothesis, under conditions scaled to represent the Sawtooth Range, Montana. A brittle sand pack, containing an upper ductile layer with variable geometry, was shortened above a ductile base and the evolution of the deformation front was monitored throughout the deformation using a high-accuracy laser scanner. In none of the experiments did the upper detachment horizon cover the entire model. In experiments where it pinched out perpendicular to the shortening direction, a triangle zone was formed when the deformation front reached the pinch out. This situation is analogous to the Teton Canyon region structures in the Sawtooth Range, Montana, where the Cretaceous Colorado Shale unit pinches out at the deformation front, favouring the development of a triangle zone in this region. When the pinch out was oblique to the shortening direction, a more complex series of structures was formed. However, when shortening stopped before the detachment pinch out was reached, the deformation front structures were foreland-propagating and no triangle zone was observed. This situation is analogous to foreland-propagating thrust structures developed at the deformation front in the Swift Dam region of the Sawtooth Range, Montana and to the development of fault-bend folds at the deformation front of the Zagros Fold-Thrust Belt, Iran. We suggest that the presence of a suitable intermediate detachment horizon within a sediment pile can be invoked as a valid explanation for the development of varied deformation front structures in fold-thrust belts. Specifically, the spatial extent of the upper detachment horizon with respect to the spatial extent of the deformed region is a key influence on the development of deformation front structures. However, we acknowledge that factors such as basement structure and variable sedimentation within the foreland basin may also be key influences on deformation front structures in other fold-thrust belts.

Astrium Preparation of Future Cryogenic Thrust Chamber Development

NASA Astrophysics Data System (ADS)

Nicolay, Rolf

2002-01-01

The scenarios for future cryogenic propulsion in Europe are mainly governed by cost issues on the one side and performance issues on the other. Certain relationships of the different issues exist to either the application for ELVs or RLVs respectively. Taking into account the limited budgets of the Europeans Agency Market, flexible development strategies are and have to be defined to fulfill both applications requirements. Investigations aiming at identifying the optimum development strategy serving both applications have been performed. Based on the experience of the different cryogenic thrust chamber developments already performed, Astrium worked out a flexible development strategy for future cryogenic thrust chambers in order to: This paper is going to report about this development strategy and the associated derived needs for technological investigations and development work.

Effect of Cutting Parameters on Thrust Force and Surface Roughness in Drilling of Al-2219/B4C/Gr Metal Matrix Composites

NASA Astrophysics Data System (ADS)

Ravindranath, V. M.; Basavarajappa, G. S. Shiva Shankar S.; Suresh, R.

2016-09-01

In aluminium matrix composites, reinforcement of hard ceramic particle present inside the matrix which causes tool wear, high cutting forces and poor surface finish during machining. This paper focuses on effect of cutting parameters on thrust force, surface roughness and burr height during drilling of MMCs. In the present work, discuss the influence of spindle speed and feed rate on drilling the pure base alloy (Al-2219), mono composite (Al- 2219+8% B4C) and hybrid composite (Al-2219+8%B4C+3%Gr). The composites were fabricated using liquid metallurgy route. The drilling experiments were conducted by CNC machine with TiN coated HSS tool, M42 (Cobalt grade) and carbide tools at various spindle speeds and feed rates. The thrust force, surface roughness and burr height of the drilled hole were investigated in mono composite and hybrid composite containing graphite particles, the experimental results show that the feed rate has more influence on thrust force and surface roughness. Lesser thrust force and discontinuous chips were produced during machining of hybrid composites when compared with mono and base alloy during drilling process. It is due to solid lubricant property of graphite which reduces the lesser thrust force, burr height and lower surface roughness. When machining with Carbide tool at low feed and high speeds good surface finish was obtained compared to other two types of cutting tool materials.

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.

An investigation of thrust, depth and the impedance cardiogram as measures of cardiopulmonary resuscitation efficacy in a porcine model of cardiac arrest.

PubMed

Howe, Andrew; O'Hare, Peter; Crawford, Paul; Delafont, Bruno; McAlister, Olibhear; Di Maio, Rebecca; Clutton, Eddie; Adgey, Jennifer; McEneaney, David

2015-11-01

Optimising the depth and rate of applied chest compressions following out of hospital cardiac arrest is crucial in maintaining end organ perfusion and improving survival. The impedance cardiogram (ICG) measured via defibrillator pads produces a characteristic waveform during chest compressions with the potential to provide feedback on cardiopulmonary resuscitation (CPR) and enhance performance. The objective of this pre-clinical study was to investigate the relationship between mechanical and physiological markers of CPR efficacy in a porcine model and examine the strength of correlation between the ICG amplitude, compression depth and end-tidal CO2 (ETCO2). Two experiments were performed using 24 swine (12 per experiment). For experiment 1, ventricular fibrillation (VF) was induced and mechanical CPR commenced at varying thrusts (0-60 kg) for 2 min intervals. Chest compression depth was recorded using a Philips QCPR device with additional recording of invasive physiological parameters: systolic blood pressure, ETCO2, cardiac output and carotid flow. For experiment 2, VF was induced and mechanical CPR commenced at varying depths (0-5 cm) for 2 min intervals. The ICG was recorded via defibrillator pads attached to the animal's sternum and connected to a Heartsine 500 P defibrillator. ICG amplitude, chest compression depth, systolic blood pressure and ETCO2 were recorded during each cycle. In both experiments the within-animal correlation between the measured parameters was assessed using a mixed effect model. In experiment 1 moderate within-animal correlations were observed between physiological parameters and compression depth (r=0.69-0.77) and thrust (r=0.66-0.82). A moderate correlation was observed between compression depth and thrust (r=0.75). In experiment 2 a strong within-animal correlation and moderate overall correlations were observed between ICG amplitude and compression depth (r=0.89, r=0.79) and ETCO2 (r=0.85, r=0.64). In this porcine model of induced cardiac arrest moderate within animal correlations were observed between mechanical and physiological markers of chest compression efficacy demonstrating the challenge in utilising a single mechanical metric to quantify chest compression efficacy. ICG amplitude demonstrated strong within animal correlations with compression depth and ETCO2 suggesting its potential utility to provide CPR feedback in the out of hospital setting to improve performance. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

The HEAO-1 neutron star timing experiment

NASA Technical Reports Server (NTRS)

Lamb, F. K.

1979-01-01

The HEAO-1 neutron star timing experiment is presented. The scientific motivation for the experiment, the reasons for the choice of Her X-1 and Vela X-1 as promising sources to study, the methodology, and the current status of the experiment are summarized.

Flowfield analysis of modern helicopter rotors in hover by Navier-Stokes method

NASA Technical Reports Server (NTRS)

Srinivasan, G. R.; Raghavan, V.; Duque, E. P. N.

1991-01-01

The viscous, three-dimensional, flowfields of UH60 and BERP rotors are calculated for lifting hover configurations using a Navier-Stokes computational fluid dynamics method with a view to understand the importance of planform effects on the airloads. In this method, the induced effects of the wake, including the interaction of tip vortices with successive blades, are captured as a part of the overall flowfield solution without prescribing any wake models. Numerical results in the form of surface pressures, hover performance parameters, surface skin friction and tip vortex patterns, and vortex wake trajectory are presented at two thrust conditions for UH60 and BERP rotors. Comparison of results for the UH60 model rotor show good agreement with experiments at moderate thrust conditions. Comparison of results with equivalent rectangular UH60 blade and BERP blade indicates that the BERP blade, with an unconventional planform, gives more thrust at the cost of more power and a reduced figure of merit. The high thrust conditions considered produce severe shock-induced flow separation for UH60 blade, while the BERP blade develops more thrust and minimal separation. The BERP blade produces a tighter tip vortex structure compared with the UH60 blade. These results and the discussion presented bring out the similarities and differences between the two rotors.

Multi-Objective Optimization of Moving-magnet Linear Oscillatory Motor Using Response Surface Methodology with Quantum-Behaved PSO Operator

NASA Astrophysics Data System (ADS)

Lei, Meizhen; Wang, Liqiang

2018-01-01

To reduce the difficulty of manufacturing and increase the magnetic thrust density, a moving-magnet linear oscillatory motor (MMLOM) without inner-stators was Proposed. To get the optimal design of maximum electromagnetic thrust with minimal permanent magnetic material, firstly, the 3D finite element analysis (FEA) model of the MMLOM was built and verified by comparison with prototype experiment result. Then the influence of design parameters of permanent magnet (PM) on the electromagnetic thrust was systematically analyzed by the 3D FEA to get the design parameters. Secondly, response surface methodology (RSM) was employed to build the response surface model of the new MMLOM, which can obtain an analytical model of the PM volume and thrust. Then a multi-objective optimization methods for design parameters of PM, using response surface methodology (RSM) with a quantum-behaved PSO (QPSO) operator, was proposed. Then the way to choose the best design parameters of PM among the multi-objective optimization solution sets was proposed. Then the 3D FEA of the optimal design candidates was compared. The comparison results showed that the proposed method can obtain the best combination of the geometric parameters of reducing the PM volume and increasing the thrust.

STAR - Research Experiences at National Laboratory Facilities for Pre-Service and Early Career Teachers

NASA Astrophysics Data System (ADS)

Keller, J. M.; Rebar, B.; Buxner, S.

2012-12-01

The STEM Teacher and Researcher (STAR) Program provides pre-service and beginning teachers the opportunity to develop identity as both teachers and researchers early in their careers. Founded and implemented by the Center for Excellence in Science and Mathematics Education (CESaME) at California Polytechnic State University on behalf of the California State University (CSU) system, STAR provides cutting edge research experiences and career development for students affiliated with the CSU system. Over the past three summers, STAR has also partnered with the NSF Robert Noyce Teacher Scholarship Program to include Noyce Scholars from across the country. Key experiences are one to three summers of paid research experience at federal research facilities associated with the Department of Energy (DOE), National Aeronautics and Space Administration (NASA), National Oceanic and Atmospheric Association (NOAA), and the National Optical Astronomy Observatory (NOAO). Anchoring beginning teachers in the research community enhances participant understanding of what it means to be both researchers and effective teachers. Since its inception in 2007, the STAR Program has partnered with 15 national lab facilities to provide 290 research experiences to 230 participants. Several of the 68 STAR Fellows participating in the program during Summer 2012 have submitted abstracts to the Fall AGU Meeting. Through continued partnership with the Noyce Scholar Program and contributions from outside funding sources, the CSU is committed to sustaining the STAR Program in its efforts to significantly impact teacher preparation. Evaluation results from the program continue to indicate program effectiveness in recruiting high quality science and math majors into the teaching profession and impacting their attitudes and beliefs towards the nature of science and teaching through inquiry. Additionally, surveys and interviews are being conducted of participants who are now teaching in the classroom as part of a project to investigate the impact of the STAR Program on teaching practices. Preliminary analyses indicate that STAR fellows have maintained a strong distributed community of support following their summer experience, including continued contact with their research mentors and other fellows. The STAR research experience has also reinforced and strengthened many of the teachers' commitment to teaching. Additionally, teachers report how their STAR experience contributed to specific practices they use in the classroom to help students develop hypotheses, design experiments, and report their findings to the class. The STAR Program was presented to and cited by the Presidential Council of Advisors on Science and Technology (PCAST) as a national model for addressing K-12 science and math teacher workforce needs. It has also been recognized as a uniquely promising model for recruiting, preparing and retaining outstanding STEM teachers in such national publications as the American Association of Colleges and Universities (AAC&U) Peer Review journal and the National Science Teachers Association NSTA Reports. STAR was also recently cited in an editorial in Science (May 4, 2012) as a model teacher-researcher program that enhances professionalism in science teaching.

Aircraft emissions of methane and nitrous oxide during the alternative aviation fuel experiment.

PubMed

Santoni, Gregory W; Lee, Ben H; Wood, Ezra C; Herndon, Scott C; Miake-Lye, Richard C; Wofsy, Steven C; McManus, J Barry; Nelson, David D; Zahniser, Mark S

2011-08-15

Given the predicted growth of aviation and the recent developments of alternative aviation fuels, quantifying methane (CH(4)) and nitrous oxide (N(2)O) emission ratios for various aircraft engines and fuels can help constrain projected impacts of aviation on the Earth's radiative balance. Fuel-based emission indices for CH(4) and N(2)O were quantified from CFM56-2C1 engines aboard the NASA DC-8 aircraft during the first Alternative Aviation Fuel Experiment (AAFEX-I) in 2009. The measurements of JP-8 fuel combustion products indicate that at low thrust engine states (idle and taxi, or 4% and 7% maximum rated thrusts, respectively) the engines emit both CH(4) and N(2)O at a mean ± 1σ rate of 170 ± 160 mg CH(4) (kg Fuel)(-1) and 110 ± 50 mg N(2)O (kg Fuel)(-1), respectively. At higher thrust levels corresponding to greater fuel flow and higher engine temperatures, CH(4) concentrations in engine exhaust were lower than ambient concentrations. Average emission indices for JP-8 fuel combusted at engine thrusts between 30% and 100% of maximum rating were -54 ± 33 mg CH(4) (kg Fuel)(-1) and 32 ± 18 mg N(2)O (kg Fuel)(-1), where the negative sign indicates consumption of atmospheric CH(4) in the engine. Emission factors for the synthetic Fischer-Tropsch fuels were statistically indistinguishable from those for JP-8.

Effect of blade outlet angle on radial thrust of single-blade centrifugal pump

NASA Astrophysics Data System (ADS)

Nishi, Y.; Fukutomi, J.; Fujiwara, R.

2012-11-01

Single-blade centrifugal pumps are widely used as sewage pumps. However, a large radial thrust acts on a single blade during pump operation because of the geometrical axial asymmetry of the impeller. This radial thrust causes vibrations of the pump shaft, reducing the service life of bearings and shaft seal devices. Therefore, to ensure pump reliability, it is necessary to quantitatively understand the radial thrust and clarify the behavior and generation mechanism. This study investigated the radial thrust acting on two kinds of single-blade centrifugal impellers having different blade outlet angles by experiments and computational fluid dynamics (CFD) analysis. Furthermore, the radial thrust was modeled by a combination of three components, inertia, momentum, and pressure, by applying an unsteady conservation of momentum to this impeller. As a result, the effects of the blade outlet angle on both the radial thrust and the modeled components were clarified. The total head of the impeller with a blade outlet angle of 16 degrees increases more than the impeller with a blade outlet angle of 8 degrees at a large flow rate. In this case, since the static pressure of the circumference of the impeller increases uniformly, the time-averaged value of the radial thrust of both impellers does not change at every flow rate. On the other hand, since the impeller blade loading becomes large, the fluctuation component of the radial thrust of the impeller with the blade outlet angle of 16 degrees increases. If the blade outlet angle increases, the fluctuation component of the inertia component will increase, but the time-averaged value of the inertia component is located near the origin despite changes in the flow rate. The fluctuation component of the momentum component becomes large at all flow rates. Furthermore, although the time-averaged value of the pressure component is almost constant, the fluctuation component of the pressure component becomes large at a large flow rate. In addition to the increase of the fluctuation component of this pressure component, because the fluctuation component of the inertia and momentum components becomes large (as mentioned above), the radial thrust increases at a large flow rate, as is the case for the impeller with a large blade outlet angle.

A Centralized Display for Mission Monitoring

NASA Technical Reports Server (NTRS)

Trujillo, Anna C.

2004-01-01

Humans traditionally experience a vigilance decrement over extended periods of time on reliable systems. One possible solution to aiding operators in monitoring is to use polar-star displays that will show deviations from normal in a more salient manner. The primary objectives of this experiment were to determine if polar-star displays aid in monitoring and preliminary diagnosis of the aircraft state. This experiment indicated that the polar-star display does indeed aid operators in detecting and diagnosing system events. Subjects were able to notice system events earlier and they subjectively reported the polar-star display helped them in monitoring, noticing an event, and diagnosing an event. Therefore, these results indicate that the polar-star display used for monitoring and preliminary diagnosis improves performance in these areas for system related events.

Attitude Control System Design for the Solar Dynamics Observatory

NASA Technical Reports Server (NTRS)

Starin, Scott R.; Bourkland, Kristin L.; Kuo-Chia, Liu; Mason, Paul A. C.; Vess, Melissa F.; Andrews, Stephen F.; Morgenstern, Wendy M.

2005-01-01

The Solar Dynamics Observatory mission, part of the Living With a Star program, will place a geosynchronous satellite in orbit to observe the Sun and relay data to a dedicated ground station at all times. SDO remains Sun- pointing throughout most of its mission for the instruments to take measurements of the Sun. The SDO attitude control system is a single-fault tolerant design. Its fully redundant attitude sensor complement includes 16 coarse Sun sensors, a digital Sun sensor, 3 two-axis inertial reference units, 2 star trackers, and 4 guide telescopes. Attitude actuation is performed using 4 reaction wheels and 8 thrusters, and a single main engine nominally provides velocity-change thrust. The attitude control software has five nominal control modes-3 wheel-based modes and 2 thruster-based modes. A wheel-based Safehold running in the attitude control electronics box improves the robustness of the system as a whole. All six modes are designed on the same basic proportional-integral-derivative attitude error structure, with more robust modes setting their integral gains to zero. The paper details the mode designs and their uses.

Emblem of the Apollo 17 lunar landing mission

NASA Technical Reports Server (NTRS)

1972-01-01

This is the Official emblem of the Apollo 17 lunar landing mission which will be flown by Astronauts Eugene A. Cernan, Ronald E. Evans and Harrison H. Schmitt. The insignia is dominated by the image of Apollo, the Greek sun god. Suspended in space behind the head of Apollo is an American eagle of contemporary design, the red bars of the eagle's wing represent the bars in the U.S. flag; the three white stars symbolize the three astronaut crewmen. The background is deep blue space and within it are the Moon, the planet Saturn and a spiral galaxy or nebula. The Moon is partially overlaid by the eagle's wing suggesting that this is a celestial body that man has visited and in that sense conquered. The thrust of the eagle and the gaze of Apollo to the right and toward Saturn and the galaxy is meant to imply that man's goals in space will someday include the planets and perhaps the stars. The colors of the emblem are red, white and blue, the colors of our flag; with the addition of gold, to

A Simple Model of Pulsed Ejector Thrust Augmentation

NASA Technical Reports Server (NTRS)

Wilson, Jack; Deloof, Richard L. (Technical Monitor)

2003-01-01

A simple model of thrust augmentation from a pulsed source is described. In the model it is assumed that the flow into the ejector is quasi-steady, and can be calculated using potential flow techniques. The velocity of the flow is related to the speed of the starting vortex ring formed by the jet. The vortex ring properties are obtained from the slug model, knowing the jet diameter, speed and slug length. The model, when combined with experimental results, predicts an optimum ejector radius for thrust augmentation. Data on pulsed ejector performance for comparison with the model was obtained using a shrouded Hartmann-Sprenger tube as the pulsed jet source. A statistical experiment, in which ejector length, diameter, and nose radius were independent parameters, was performed at four different frequencies. These frequencies corresponded to four different slug length to diameter ratios, two below cut-off, and two above. Comparison of the model with the experimental data showed reasonable agreement. Maximum pulsed thrust augmentation is shown to occur for a pulsed source with slug length to diameter ratio equal to the cut-off value.

Thrust shock vector control of an axisymmetric conical supersonic nozzle via secondary transverse gas injection

NASA Astrophysics Data System (ADS)

Zmijanovic, V.; Lago, V.; Sellam, M.; Chpoun, A.

2014-01-01

Transverse secondary gas injection into the supersonic flow of an axisymmetric convergent-divergent nozzle is investigated to describe the effects of the fluidic thrust vectoring within the framework of a small satellite launcher. Cold-flow dry-air experiments are performed in a supersonic wind tunnel using two identical supersonic conical nozzles with the different transverse injection port positions. The complex three-dimensional flow field generated by the supersonic cross-flows in these test nozzles was examined. Valuable experimental data were confronted and compared with the results obtained from the numerical simulations. Different nozzle models are numerically simulated under experimental conditions and then further investigated to determine which parameters significantly affect thrust vectoring. Effects which characterize the nozzle and thrust vectoring performances are established. The results indicate that with moderate secondary to primary mass flow rate ratios, ranging around 5 %, it is possible to achieve pertinent vector side forces. It is also revealed that injector positioning and geometry have a strong effect on the shock vector control system and nozzle performances.

3D Structure of the Inverse Karman Vortex Street in the Wake of a Flapping Foil

NASA Astrophysics Data System (ADS)

Bozkurttas, Meliha; Mittal, Rajat; Dong, Haibo

2004-11-01

Flapping foils are being considered for lift generation and/or propulsion in Micro Aerial Vehicles (MAVs) and Autonomous Underwater Vehicles (AUVs). In the present study, a DNS/LES solver that is capable of simulating these flows in all their complexity will be used. The flow around a NACA 0012 foil undergoing pitch oscillation at a chord Reynolds number of 12600 has been investigated and the comparison of mean thrust coefficient results with the experiment has indicated significant under-prediction of the thrust although good match is observed with a 2D RANS calculation. This discrepancy could be related to the absence of 3D effects in both numerical simulations. Although this conclusion has also been reached in other studies, the details of the physical mechanism that lead to inaccurate prediction of surface pressure and ultimately to thrust force for pitching and heaving flapping foils have not been clarified yet. In this study, the streamwise (secondary) vortical structures in the inverse Karman Vortex Street generated in the wake of a thrust producing flapping foil will be studied.

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.

Hovering Dual-Spin Vehicle Groundwork for Bias Momentum Sizing Validation Experiment

NASA Technical Reports Server (NTRS)

Rothhaar, Paul M.; Moerder, Daniel D.; Lim, Kyong B.

2008-01-01

Angular bias momentum offers significant stability augmentation for hovering flight vehicles. The reliance of the vehicle on thrust vectoring for agility and disturbance rejection is greatly reduced with significant levels of stored angular momentum in the system. A methodical procedure for bias momentum sizing has been developed in previous studies. This current study provides groundwork for experimental validation of that method using an experimental vehicle called the Dual-Spin Test Device, a thrust-levitated platform. Using measured data the vehicle's thrust vectoring units are modeled and a gust environment is designed and characterized. Control design is discussed. Preliminary experimental results of the vehicle constrained to three rotational degrees of freedom are compared to simulation for a case containing no bias momentum to validate the simulation. A simulation of a bias momentum dominant case is presented.

Entrainment and thrust augmentation in pulsatile ejector flows

NASA Technical Reports Server (NTRS)

Sarohia, V.; Bernal, L.; Bui, T.

1981-01-01

This study comprised direct thrust measurements, flow visualization by use of a spark shadowgraph technique, and mean and fluctuating velocity measurements with a pitot tube and linearized constant temperature hot-wire anemometry respectively. A gain in thrust of as much as 10 to 15% was observed for the pulsatile ejector flow as compared to the steady flow configuration. From the velocity profile measurements, it is concluded that this enhanced augmentation for pulsatile flow as compared to a nonpulsatile one was accomplished by a corresponding increased entrainment by the primary jet flow. It is also concluded that the augmentation and total entrainment by a constant area ejector critically depends upon the inlet geometry of the ejector. Experiments were performed to evaluate the influence of primary jet to ejector area ratio, ejector length, and presence of a diffuser on pulsatile ejector performance.

Experience with high performance V/STOL fighter projects at MBB

NASA Technical Reports Server (NTRS)

Aulehla, F.; Kissel, G. K.

1981-01-01

Flight control systems and aerodynamic aspects of experimental V/STOL aircraft are discussed. The VJ 101 C featured tilting engines for increased thrust, reheat for takeoff, simple translation, triangular decentralization of the engines for thrust modulation, and moderate ground effects. Two experimental aircraft were built, with and without reheat, capable of Mach 2 and Mach 1.04, respectively. The mechanical flight control system and tests are outlined, both for hover rig and flight configurations. Ground suction, acoustic and thermal loading, sodium silicate coatings to avoid ground corrosion, and recirculation are considered. Results of the follow-on project to the VJ 101 C, the AVS, which was developed by NASA, are reviewed, and it is noted that trends toward thrust-to-weight ratios exceeding one, in concert with low wing loading, favor the development of V/STOL aircraft.

Establishing the Galactic Centre distance using VVV Bulge RR Lyrae variables

NASA Astrophysics Data System (ADS)

Majaess, D.; Dékány, I.; Hajdu, G.; Minniti, D.; Turner, D.; Gieren, W.

2018-06-01

This study's objective was to exploit infrared VVV (VISTA Variables in the Via Lactea) photometry for high latitude RRab stars to establish an accurate Galactic Centre distance. RRab candidates were discovered and reaffirmed (n=4194) by matching Ks photometry with templates via χ 2 minimization, and contaminants were reduced by ensuring targets adhered to a strict period-amplitude (Δ Ks) trend and passed the Elorietta et al. classifier. The distance to the Galactic Centre was determined from a high latitude Bulge subsample (|b|>4°, R_{GC}=8.30 ± 0.36 kpc, random uncertainty is relatively negligible), and importantly, the comparatively low color-excess and uncrowded location mitigated uncertainties tied to the extinction law, the magnitude-limited nature of the analysis, and photometric contamination. Circumventing those problems resulted in a key uncertainty being the M_{Ks} relation, which was derived using LMC RRab stars (M_{Ks}=-(2.66± 0.06) log {P}-(1.03± 0.06), (J-Ks)0=(0.31± 0.04) log {P} + (0.35± 0.02), assuming μ _{0,LMC}=18.43). The Galactic Centre distance was not corrected for the cone-effect. Lastly, a new distance indicator emerged as brighter overdensities in the period-magnitude-amplitude diagrams analyzed, which arise from blended RRab and red clump stars. Blending may thrust faint extragalactic variables into the range of detectability.

Mechanic watches a General Electric I-40 Engine Fire

NASA Image and Video Library

1948-01-21

A mechanic watches the firing of a General Electric I-40 turbojet at the National Advisory Committee for Aeronautics (NACA) Lewis Flight Propulsion Laboratory. The military selected General Electric’s West Lynn facility in 1941 to secretly replicate the centrifugal turbojet engine designed by British engineer Frank Whittle. General Electric’s first attempt, the I-A, was fraught with problems. The design was improved somewhat with the subsequent I-16 engine. It was not until the engine's next reincarnation as the I-40 in 1943 that General Electric’s efforts paid off. The 4000-pound thrust I-40 was incorporated into the Lockheed Shooting Star airframe and successfully flown in June 1944. The Shooting Star became the US’s first successful jet aircraft and the first US aircraft to reach 500 miles per hour. NACA Lewis studied all of General Electric’s centrifugal turbojet models during the 1940s. In 1945 the entire Shooting Star aircraft was investigated in the Altitude Wind Tunnel. Engine compressor performance and augmentation by water injection; comparison of different fuel blends in a single combustor; and air-cooled rotors were studied. The mechanic in this photograph watches the firing of a full-scale I-40 in the Jet Propulsion Static Laboratory. The facility was quickly built in 1943 specifically in order to test the early General Electric turbojets. The I-A was secretly analyzed in the facility during the fall of 1943.

Exploring Women Community College Natural Scientists' Personal Experience Narratives through a Subjectivist Lens

ERIC Educational Resources Information Center

Woods, Nancy Anne

2010-01-01

The thrust in education today is to encourage young women to enter nontraditional fields of study such as chemistry, physics, and biology. In order to better prepare the next generation of women scientists, then, we should examine the experiences of women participants already working within these areas. We can learn from their experiences. What…

Application of Taguchi-grey method to optimize drilling of EMS 45 steel using minimum quantity lubrication (MQL) with multiple performance characteristics

NASA Astrophysics Data System (ADS)

Soepangkat, Bobby O. P.; Suhardjono, Pramujati, Bambang

2017-06-01

Machining under minimum quantity lubrication (MQL) has drawn the attention of researchers as an alternative to the traditionally used wet and dry machining conditions with the purpose to minimize the cooling and lubricating cost, as well as to reduce cutting zone temperature, tool wear, and hole surface roughness. Drilling is one of the important operations to assemble machine components. The objective of this study was to optimize drilling parameters such as cutting feed and cutting speed, drill type and drill point angle on the thrust force, torque, hole surface roughness and tool flank wear in drilling EMS 45 tool steel using MQL. In this study, experiments were carried out as per Taguchi design of experiments while an L18 orthogonal array was used to study the influence of various combinations of drilling parameters and tool geometries on the thrust force, torque, hole surface roughness and tool flank wear. The optimum drilling parameters was determined by using grey relational grade obtained from grey relational analysis for multiple-performance characteristics. The drilling experiments were carried out by using twist drill and CNC machining center. This work is useful for optimum values selection of various drilling parameters and tool geometries that would not only minimize the thrust force and torque, but also reduce hole surface roughness and tool flank wear.

Measurements of energy distribution and thrust for microwave plasma coupling of electrical energy to hydrogen for propulsion

NASA Technical Reports Server (NTRS)

Morin, T.; Chapman, R.; Filpus, J.; Hawley, M.; Kerber, R.; Asmussen, J.; Nakanishi, S.

1982-01-01

A microwave plasma system for transfer of electrical energy to hydrogen flowing through the system has potential application for coupling energy to a flowing gas in the electrothermal propulsion concept. Experimental systems have been designed and built for determination of the energy inputs and outputs and thrust for the microwave coupling of energy to hydrogen. Results for experiments with pressure in the range 100 microns-6 torr, hydrogen flow rate up to 1000 micronmoles/s, and total absorbed power to 700 w are presented.

Effect of spiral outlet hydraulic passage geometrics on the radial thrust

NASA Astrophysics Data System (ADS)

Lugova, S. O.; Ignateva, P. I.

2017-08-01

The article presents the results of investigation of the effect of geometrics of a double-volute outlet hydraulic passage on the magnitude and direction of acting of the radial reaction forces in a between-bearings single-stage centrifugal pump with a double entry impeller. The investigation has been performed with the use of a computing experiment. Characteristic curves as well as values and directions of the radial thrust have been compared for three variants of outlet hydraulic passages differing in the width at their entrance.

The Washington experience (evaluation and selection of hardware for automated geo-based information systems)

NASA Technical Reports Server (NTRS)

Harding, R. A.

1981-01-01

A Washington geographic information system is described. The system has thrust from two different angles: the proprietary need for information to support the management of five million acres of thrust lands by the Department of Natural Resources, and the need for data over the entire state because of statewide governmental responsibilities. The data base includes information relevant to agricultural, forest, industrial, business, and community growth with emphasis on assembling information useful in setting intermediate and long-range goals. System selection procedures and system feasibility studies are discussed.

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.

The Hydrodynamics of Plesiosaurs

NASA Astrophysics Data System (ADS)

Muscutt, Luke; Ganapathisubramani, Bharathram; Dyke, Gareth; Weymouth, Gabriel

2015-11-01

Plesiosaurs are extinct marine reptiles that existed at the same time as the dinosaurs, and are the only known animals to swim by actively flapping their four wing-like flippers. This can be viewed as a tandem flapping wing problem, where the hind wing is operating in the wake of the fore wing. Experiments using full-scale robotic plesiosaur flippers in a large flume tank have been used to investigate the kinematics and interaction of the flippers. The flippers are actuated in heave and pitch, and a combination of force measurements and flow visualization are used to analyze the characteristics of the vortex interaction between the flippers. Previous two-dimensional numerical simulations have shown that certain kinematics give an increase in thrust of the hind flipper of up to 50%. The current experiments determine if such thrust augmentation is present for a three-dimensional flowfield and determine the kinematics that give the highest possible thrust. This will help to answer paleo-biological questions about the function and evolution of the plesiosaur flippers, along with helping to determine if tandem flapping wings could be a viable propulsion system for autonomous underwater vehicles. Support from EPSRC and Ginko Investments Ltd.

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.

Star Identification Without Attitude Knowledge: Testing with X-Ray Timing Experiment Data

NASA Technical Reports Server (NTRS)

Ketchum, Eleanor

1997-01-01

As the budget for the scientific exploration of space shrinks, the need for more autonomous spacecraft increases. For a spacecraft with a star tracker, the ability to determinate attitude from a lost in space state autonomously requires the capability to identify the stars in the field of view of the tracker. Although there have been efforts to produce autonomous star trackers which perform this function internally, many programs cannot afford these sensors. The author previously presented a method for identifying stars without a priori attitude knowledge specifically targeted for onboard computers as it minimizes the necessary computer storage. The method has previously been tested with simulated data. This paper provides results of star identification without a priori attitude knowledge using flight data from two 8 by 8 degree charge coupled device star trackers onboard the X-Ray Timing Experiment.

Star tracking method based on multiexposure imaging for intensified star trackers.

PubMed

Yu, Wenbo; Jiang, Jie; Zhang, Guangjun

2017-07-20

The requirements for the dynamic performance of star trackers are rapidly increasing with the development of space exploration technologies. However, insufficient knowledge of the angular acceleration has largely decreased the performance of the existing star tracking methods, and star trackers may even fail to track under highly dynamic conditions. This study proposes a star tracking method based on multiexposure imaging for intensified star trackers. The accurate estimation model of the complete motion parameters, including the angular velocity and angular acceleration, is established according to the working characteristic of multiexposure imaging. The estimation of the complete motion parameters is utilized to generate the predictive star image accurately. Therefore, the correct matching and tracking between stars in the real and predictive star images can be reliably accomplished under highly dynamic conditions. Simulations with specific dynamic conditions are conducted to verify the feasibility and effectiveness of the proposed method. Experiments with real starry night sky observation are also conducted for further verification. Simulations and experiments demonstrate that the proposed method is effective and shows excellent performance under highly dynamic conditions.

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.

Experimental and numerical investigations on PDE performance augmentation by means of an ejector

NASA Astrophysics Data System (ADS)

Canteins, G.; Franzetti, F.; Zocłońska, E.; Khasainov, B. A.; Zitoun, R.; Desbordes, D.

2006-06-01

To improve the performance of pulse detonation engines, a 48 cm long cylindrical combustion chamber of 5cm internal diameter (i.d.) is fitted with an ejector of constant section. The role of the ejector is (i) to provide partial confinement of the detonation products escaping from the chamber and (ii) to suck in fresh air and then to increase the mass ejected compared to the ejection of burned gases alone. The combustion chamber is fully filled with a stoichiometric ethylene/oxygen mixture at ambient conditions. Three parameters of the ejector are varied: the i.d. D, the length L, and the position d relative to the thrust wall of the combustion chamber. For various configurations, the specific impulse ( I sp) is determined in single shot experiments. The maximum operating frequency ( f max) and the maximum thrust are then deduced. I sp is measured by means of the ballistic pendulum method, and f max is derived from the pressure signal recorded on the combustion chamber thrust wall. The addition of an ejector increases the specific impulse up to 60% in the best configuration tested, from 164s without ejector to 260s with ejector. The specific impulse can be represented by a single curve using suitable dimensionless parameters. The thrust results for the main ejector studied ( D = 80mm) indicate an optimal ( L, d) configuration that provides a 28% thrust gain. For the same ejector, f max remains constant and equal to the frequency obtained without ejector in a large range of ( L, d) values, before decreasing. Two-dimensional unsteady numerical computations agree reasonably with the experiments, slightly overestimating the experimental values. The results indicate that 80% of the I sp gain comes from the action of the expanding detonation products on the annular end surface of the combustion chamber, governed by the tube wall thickness.

Results From a Parametric Acoustic Liner Experiment Using P and W GEN1 HSR Mixer/Ejector Model

NASA Technical Reports Server (NTRS)

Boyd, Kathleen C.; Wolter, John D.

2004-01-01

This report documents the results of an acoustic liner test performed using a Gen 1 HSR mixer/ejector model installed on the Jet Exit Rig in the Nozzle Acoustic Test Rig in the Aeroacoustic Propulsion Laboratory or NASA Glenn Research Center. Acoustic liner effectiveness and single-component thrust performance results are discussed. Results from 26 different types of single-degree-of-freedom and bulk material liners are compared with each other and against a hardwall baseline. Design parameters involving all aspects of the facesheet, the backing cavity, and the type of bulk material were varied in order to study the effects of these design features on the acoustic impedance, acoustic effectiveness and on nozzle thrust performance. Overall, the bulk absorber liners are more effective at reducing the jet noise than the single-degree-of-freedom liners. Many of the design parameters had little effect on acoustic effectiveness, such as facesheeet hole diameter and honeycomb cell size. A relatively large variation in the impedance of the bulk absorber in a bulk liner is required to have a significant impact on the noise reduction. The thrust results exhibit a number of consistent trends, supporting the validity of this new addition to the facility. In general, the thrust results indicate that thrust performance benefits from increased facesheet thickness and decreased facesheet porosity.

Centroiding Experiment for Determining the Positions of Stars with High Precision

NASA Astrophysics Data System (ADS)

Yano, T.; Araki, H.; Hanada, H.; Tazawa, S.; Gouda, N.; Kobayashi, Y.; Yamada, Y.; Niwa, Y.

2010-12-01

We have experimented with the determination of the positions of star images on a detector with high precision such as 10 microarcseconds, required by a space astrometry satellite, JASMINE. In order to accomplish such a precision, we take the following two procedures. (1) We determine the positions of star images on the detector with the precision of about 0.01 pixel for one measurement, using an algorithm for estimating them from photon weighted means of the star images. (2) We determine the positions of star images with the precision of about 0.0001-0.00001 pixel, which corresponds to that of 10 microarcseconds, using a large amount of data over 10000 measurements, that is, the error of the positions decreases according to the amount of data. Here, we note that the procedure 2 is not accomplished when the systematic error in our data is not excluded adequately even if we use a large amount of data. We first show the method to determine the positions of star images on the detector using photon weighted means of star images. This algorithm, used in this experiment, is very useful because it is easy to calculate the photon weighted mean from the data. This is very important in treating a large amount of data. Furthermore, we need not assume the shape of the point spread function in deriving the centroid of star images. Second, we show the results in the laboratory experiment for precision of determining the positions of star images. We obtain that the precision of estimation of positions of star images on the detector is under a variance of 0.01 pixel for one measurement (procedure 1). We also obtain that the precision of the positions of star images becomes a variance of about 0.0001 pixel using about 10000 measurements (procedure 2).

Preservice Teachers as Agents of Change: An Experiment. Teacher Education Forum; Volume 4, Number 3.

ERIC Educational Resources Information Center

Mohn, Norman; Reinhartz, Judy

This paper is a description of an undergraduate experiment initiated at the University of Texas at Arlington during the academic year 1974-75. The thrust of the experiment was to instill more realism in the professional courses at the Education Department and simultaneously to assist in instigating changes in the public schools. A document…

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.

Effect of tool geometry and cutting parameters on delamination and thrust forces in drilling CFRP/Al-Li

NASA Astrophysics Data System (ADS)

El Bouami, Souhail; Habak, Malek; Franz, Gérald; Velasco, Raphaël; Vantomme, Pascal

2016-10-01

Composite materials are increasingly used for structural parts in the aeronautic industries. Carbon Fiber-Reinforced Plastics (CFRP) are often used in combination with metallic materials, mostly aluminium alloys. This raises new problems in aircraft assembly. Delamination is one of these problems. In this study, CFRP/Al-Li stacks is used as experimental material for investigation effect of interaction of cutting parameters (cutting speed and feed rate) and tool geometry on delamination and thrust forces in drilling operation. A plan of experiments, based on Taguchi design method, was employed to investigate the influence of tool geometry and in particular the point angle and cutting parameters on delamination and axial effort. The experimental results demonstrate that the feed rate is the major parameter and the importance of tool point angle in delamination and thrust forces in the stacks were shown.

Flat-ramp vs. convex-concave thrust geometries in a deformable hanging wall: new insights from analogue modeling experiments

NASA Astrophysics Data System (ADS)

Almeida, Pedro; Tomas, Ricardo; Rosas, Filipe; Duarte, Joao; Terrinha, Pedro

2015-04-01

Different modes of strain accommodation affecting a deformable hanging-wall in a flat-ramp-flat thrust system were previously addressed through several (sandbox) analog modeling studies, focusing on the influence of different variables, such as: a) thrust ramp dip angle and friction (Bonini et al, 2000); b) prescribed thickness of the hanging-wall (Koy and Maillot, 2007); and c) sin-thrust erosion (compensating for topographic thrust edification, e.g. Persson and Sokoutis, 2002). In the present work we reproduce the same experimental procedure to investigate the influence of two different parameters on hanging-wall deformation: 1) the geometry of the thrusting surface; and 2) the absence of a velocity discontinuity (VD) that is always present in previous similar analogue modeling studies. Considering the first variable we use two end member ramp geometries, flat-ramp-flat and convex-concave, to understand the control exerted by the abrupt ramp edges in the hanging-wall stress-strain distribution, comparing the obtain results with the situation in which such edge singularities are absent (convex-concave thrust ramp). Considering the second investigated parameter, our motivation was the recognition that the VD found in the different analogue modeling settings simply does not exist in nature, despite the fact that it has a major influence on strain accommodation in the deformable hanging-wall. We thus eliminate such apparatus artifact from our models and compare the obtained results with the previous ones. Our preliminary results suggest that both investigated variables play a non-negligible role on the structural style characterizing the hanging-wall deformation of convergent tectonic settings were such thrust-ramp systems were recognized. Acknowledgments This work was sponsored by the Fundação para a Ciência e a Tecnologia (FCT) through project MODELINK EXPL/GEO-GEO/0714/2013. Pedro Almeida wants to thank to FCT for the Ph.D. grant (SFRH/BD/52556/2014) under the Doctoral Program EarthSystems in IDL/UL. References Bonini, M., Sokoutis, D., Mulugeta, G., Katrivanos, E. (2000) - Modelling hanging wall accommodation above rigid thrust ramps. Journal of Structural Geology, 22, pp. 1165-1179. Persson, K. & Sokoutis, D (2002) - Analogue models of orogenic wedges controlled by erosion. Tectonophysics, 356, pp. 323- 336. Koy, H. & Bertrand, M. (2007) - Tectonic thickening of hanging-wall units over a ramp.Journal of Structural Geology, 29, pp. 924-932.

Independent Orbiter Assessment (IOA): Analysis of the guidance, navigation, and control subsystem

NASA Technical Reports Server (NTRS)

Trahan, W. H.; Odonnell, R. A.; Pietz, K. C.; Hiott, J. M.

1986-01-01

The results of the Independent Orbiter Assessment (IOA) of the Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL) is presented. The IOA approach features a top-down analysis of the hardware to determine failure modes, criticality, and potential critical items. To preserve independence, this analysis was accomplished without reliance upon the results contained within the NASA FMEA/CIL documentation. The independent analysis results corresponding to the Orbiter Guidance, Navigation, and Control (GNC) Subsystem hardware are documented. The function of the GNC hardware is to respond to guidance, navigation, and control software commands to effect vehicle control and to provide sensor and controller data to GNC software. Some of the GNC hardware for which failure modes analysis was performed includes: hand controllers; Rudder Pedal Transducer Assembly (RPTA); Speed Brake Thrust Controller (SBTC); Inertial Measurement Unit (IMU); Star Tracker (ST); Crew Optical Alignment Site (COAS); Air Data Transducer Assembly (ADTA); Rate Gyro Assemblies; Accelerometer Assembly (AA); Aerosurface Servo Amplifier (ASA); and Ascent Thrust Vector Control (ATVC). The IOA analysis process utilized available GNC hardware drawings, workbooks, specifications, schematics, and systems briefs for defining hardware assemblies, components, and circuits. Each hardware item was evaluated and analyzed for possible failure modes and effects. Criticality was assigned based upon the severity of the effect for each failure mode.

Studies of Operating Frequency Effects On Ejector-based Thrust Augmentation in a Pulse Detonation Engine

NASA Technical Reports Server (NTRS)

Landry, K.

2005-01-01

Studies were performed in order to characterize the thrust augmentation potential of an ejector in a Pulse Detonation Engine application. A 49-mm diameter tube of 0.914-m length was constructed with one open end and one closed end. Ethylene, oxygen, and nitrogen were introduced into the tube at the closed end through the implementation of a fast mixing injector. The tube was completely filled with a stoichiometric mixture containing a one to one molar ratio of nitrogen to oxygen. Ethylene was selected as the fuel due to its detonation sensitivity and the molar ratio of the oxidizer was chosen for heat transfer purposes. Detonations were initiated in the tube through the use of a spark ignition system. The PDE was operated in a multi-cycle mode at frequencies ranging from 20-Hz to 50-Hz. Baseline thrust measurements with no ejector present were performed while operating the engine at various frequencies and compared to theoretical estimates. The baseline values were observed to agree with the theoretical model at low operating frequencies and proved to be increasingly lower than the predicted values as the operating frequency was increased. The baseline thrust measurements were observed to agree within 15 percent of the model for all operating frequencies. A straight 152-mm diameter ejector was installed and thrust augmentation percentages were measured. The length of the ejector was varied while the overlap percentage (percent of the ejector length which overlapped the tube) was maintained at 25 percent for all tests. In addition, the effect of ejector inlet geometry was investigated by comparing results with a straight inlet to those of a 38-mm inlet diameter. The thrust augmentation of the straight inlet ejector proved to be independent of engine operating frequency, augmenting thrust by 40 percent for the 0.914-m length ejector. In contrast, the rounded lip ejector of the same length seemed to be highly dependent on the engine operating frequency. An optimum operating frequency observed with the rounded inlet occurred at an operating frequency of 30-Hz, resulting in thrust augmentation percentages greater than 100 percent. The effect that the engine operating frequency had on thrust augmentation levels attained with an ejector was characterized and optimum performance parameters were established. Insight into the frequency dependent nature of the ejector performance was pursued. Suggestions for future experiments which are needed to fully understand the means in which thrust augmentation is achieved in a PDE-ejector configuration were noted.

Indoor Astronomy: A Model Eclipsing Binary Star System.

ERIC Educational Resources Information Center

Bloomer, Raymond H., Jr.

1979-01-01

Describes a two-hour physics laboratory experiment modeling the phenomena of eclipsing binary stars developed by the Air Force Academy as part of a week-long laboratory-oriented experience for visiting high school students. (BT)

Experimental investigation of the effects of variable expanding channel on the performance of a low-power cusped field thruster

NASA Astrophysics Data System (ADS)

Liu, Hui; Zeng, Ming; Jiang, Wenjia; Yang, Chiyu; Ning, Zhongxi; Yu, Daren

2018-04-01

Due to a special magnetic field structure, the multi-cusped field thruster shows advantages of low wall erosion, low noise and high thrust density over a wide range of thrust. In this paper, expanding discharge channels are employed to make up for deficiencies on the range of thrust and plume divergence, which often emerges in conventional straight cylindrical channels. Three thruster geometries are fabricated with different expanding-angle channels, and a group of experiments are carried out to find out their influence on the performance and discharge characteristics of the thruster. A retarding potential analyzer and a Faraday probe are employed to analyze the structures of the plume in these three models. The results show that when the thrusters operate at low mass flow rate, the gradually-expanding channels exhibit lower propellant utilization and lower overall performance by amounts not exceeding 44.8% in ionization rate and 19.5% in anode efficiency, respectively. But the weakening of magnetic field intensity near the exit of expanding channels leads to an extended thrust throttling ability, a smaller plume divergence angle, and a relatively larger stable operating space without mode converting and the consequent performance degradation.

Kalman Filter for Mass Property and Thrust Identification (MMS)

NASA Technical Reports Server (NTRS)

Queen, Steven

2015-01-01

The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories, elliptically orbiting the Earth in a tetrahedron formation. For the operational success of the mission, on-board systems must be able to deliver high-precision orbital adjustment maneuvers. On MMS, this is accomplished using feedback from on-board star sensors in tandem with accelerometers whose measurements are dynamically corrected for errors associated with a spinning platform. In order to determine the required corrections to the measured acceleration, precise estimates of attitude, rate, and mass-properties is necessary. To this end, both an on-board and ground-based Multiplicative Extended Kalman Filter (MEKF) were formulated and implemented in order to estimate the dynamic and quasi-static properties of the spacecraft.

Supersonic fan engines for military aircraft

NASA Technical Reports Server (NTRS)

Franciscus, L. C.

1983-01-01

Engine performance and mission studies were performed for turbofan engines with supersonic through-flow fans. A Mach 2.4 CTOL aircraft was used in the study. Two missions were considered: a long range penetrator mission and a long range intercept mission. The supersonic fan engine is compared with an augmented mixed flow turbofan in terms of mission radius for a fixed takeoff gross weight of 75,000 lbm. The mission radius of aircraft powered by supersonic fan engines could be 15 percent longer than aircraft powered with conventional turbofan engines at moderate thrust to gross weight ratios. The climb and acceleration performance of the supersonic fan engines is better than that of the conventional turbofan engines. Previously announced in STAR as N83-34947

Tectono-sedimentary evolution of salt controlled minibasin in a fold-an-thrust belt setting Example from the Sivas Basin Turkey and physical model.

NASA Astrophysics Data System (ADS)

Kergaravat, Charlie; Ribes, Charlotte; Darnault, Romain; Callot, Jean-Paul; Ringenbach, Jean-Claude

2017-04-01

The aim of this study is to present the influence of regional shortening on the evolution of a minibasin province and the associated foldbelt geometry based on a natural example, the Sivas Basin, then compared to a physical experiment. The Sivas Basin in the Central Anatolian Plateau (Turkey) is a foreland fold-and-thrust belt, displaying in the central part a typical wall and basin province characterized by spectacularly exposed minibasins, separated by continuous steep-flanked walls and diapirs over a large area (45x25 km). The advance of the orogenic wedge is expressed within the second generation of minibasins by a shortening-induced squeezing of diapirs. Network of walls and diapirs evolve form polygonal to linear pattern probably induced by the squeezing of pre-existing evaporite walls and diapirs, separating linear primary minibasins. From base to top of secondary minibasins, halokinetic structures seem to evolve from small-scale objects along diapir flanks, showing hook and wedges halokinetic sequences, to large stratigraphic wedging, megaflap and salt sheets. Minibasins show progressively more linear shape at right angle to the regional shortening and present angular unconformities along salt structures related to the rejuvenation of pre-existing salt diapirs and walls probably encouraged by the shortening tectonic regime. The advance of the fold-and-thrust belts during the minibasins emplacement is mainly expressed during the late stage of minibasins development by a complex polygonal network of small- and intermediate-scale tectonic objects: (1) squeezed evaporite walls and diapirs, sometimes thrusted forming oblique or vertical welds, (2) allochthonous evaporite sheets, (3) thrusts and strike-slip faults recording translation and rotation of minibasins about vertical axis. Some minibasins are also tilted, with up to vertical position, associated with both the salt expulsion during minibasins sinking, recorded by large stratigraphic wedge, and the late thrust faults developments. The influence of the regional shortening deformation seems to be effective when the majority of the evaporite is remobilized toward the foreland. Results of scaled physical experiments, where continuous shortening is applied during minibasins emplacement, closely match with the deformation patterns observed in the Sivas minibasins. Shortening induce deformations such as translation of minibasins basinward, strike-slip fault zones along minibasin margin, rejuvenation of silicon walls and diapirs, emergence of silicon glaciers and rotation of minibasins along vertical and horizontal axis.

Experiences of Judeo-Christian Students in Undergraduate Biology

ERIC Educational Resources Information Center

Barnes, M. Elizabeth; Truong, Jasmine M.; Brownell, Sara E.

2017-01-01

A major research thrust in science, technology, engineering, and mathematics (STEM) education is focused on how to retain students as STEM majors. The accumulation of seemingly insignificant negative experiences in STEM classes can, over time, lead STEM students to have a low sense of belonging in their disciplines, and this can lead to lower…

Degradation and Characterization of Antimisting Kerosene (AMK).

DTIC Science & Technology

1982-12-01

EXECUTIVE SUMMARY ................................................... I. INTRODUCTION ............................................... 2 II. DEGRADER...P - density Pll-P22 - normal stress difference P12 - shear stress x EXECUTIVE SI-9ARY CSingle pass degradation of Antinmisting Kerosene (ANIK) has...While the jet thrust experiment is more difficult to execute and interpret than flow experiments, a quality control test based on normal stresses would

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.

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.

Investigation of Recombination Processes In A Magnetized Plasma

NASA Technical Reports Server (NTRS)

Chavers, Greg; Chang-Diaz, Franklin; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

Interplanetary travel requires propulsion systems that can provide high specific impulse (Isp), while also having sufficient thrust to rapidly accelerate large payloads. One such propulsion system is the Variable Specific Impulse Magneto-plasma Rocket (VASIMR), which creates, heats, and exhausts plasma to provide variable thrust and Isp, optimally meeting the mission requirements. A large fraction of the energy to create the plasma is frozen in the exhaust in the form of ionization energy. This loss mechanism is common to all electromagnetic plasma thrusters and has an impact on their efficiency. When the device operates at high Isp, where the exhaust kinetic energy is high compared to the ionization energy, the frozen flow component is of little consequence; however, at low Isp, the effect of the frozen flow may be important. If some of this energy could be recovered through recombination processes, and re-injected as neutral kinetic energy, the efficiency of VASIMR, in its low Isp/high thrust mode may be improved. In this operating regime, the ionization energy is a large portion of the total plasma energy. An experiment is being conducted to investigate the possibility of recovering some of the energy used to create the plasma. This presentation will cover the progress and status of the experiment involving surface recombination of the plasma.

Experiment D005: Star occultation navigation

NASA Technical Reports Server (NTRS)

Silva, R. M.; Jorris, T. R.; Vallerie, E. M., III

1971-01-01

The usefulness of star occultation measurements for space navigation and the determination of a horizon density profile which could be used to update atmospheric models for horizon-based measurement systems were studied. The time of occultation of a known star by a celestial body, as seen by an orbiting observer, determines a cylinder of position, the axis of which is the line through the star and the body center, and the radius of which is equal to the occulting-body radius. The dimming percentage, with respect to the altitude of this grazing ray from the star to the observer, is a percentage altitude for occultation. That is, the star can be assumed to be occulted when it reaches a predetermined percentage of its unattenuated value. The procedure used was to measure this attenuation with respect to time to determine the usefulness of the measurements for autonomous space navigation. In this experiment, the crewmembers had to accomplish star acquisition, identification, calibration, and tracking. Instrumentation was required only for measurement of the relative intensity of the star as it set into the atmosphere.

STARS: An Integrated, Multidisciplinary, Finite-Element, Structural, Fluids, Aeroelastic, and Aeroservoelastic Analysis Computer Program

NASA Technical Reports Server (NTRS)

Gupta, K. K.

1997-01-01

A multidisciplinary, finite element-based, highly graphics-oriented, linear and nonlinear analysis capability that includes such disciplines as structures, heat transfer, linear aerodynamics, computational fluid dynamics, and controls engineering has been achieved by integrating several new modules in the original STARS (STructural Analysis RoutineS) computer program. Each individual analysis module is general-purpose in nature and is effectively integrated to yield aeroelastic and aeroservoelastic solutions of complex engineering problems. Examples of advanced NASA Dryden Flight Research Center projects analyzed by the code in recent years include the X-29A, F-18 High Alpha Research Vehicle/Thrust Vectoring Control System, B-52/Pegasus Generic Hypersonics, National AeroSpace Plane (NASP), SR-71/Hypersonic Launch Vehicle, and High Speed Civil Transport (HSCT) projects. Extensive graphics capabilities exist for convenient model development and postprocessing of analysis results. The program is written in modular form in standard FORTRAN language to run on a variety of computers, such as the IBM RISC/6000, SGI, DEC, Cray, and personal computer; associated graphics codes use OpenGL and IBM/graPHIGS language for color depiction. This program is available from COSMIC, the NASA agency for distribution of computer programs.

Galileo Attitude Determination: Experiences with a Rotating Star Scanner

NASA Technical Reports Server (NTRS)

Merken, L.; Singh, G.

1991-01-01

The Galileo experience with a rotating star scanner is discussed in terms of problems encountered in flight, solutions implemented, and lessons learned. An overview of the Galileo project and the attitude and articulation control subsystem is given and the star scanner hardware and relevant software algorithms are detailed. The star scanner is the sole source of inertial attitude reference for this spacecraft. Problem symptoms observed in flight are discussed in terms of effects on spacecraft performance and safety. Sources of thse problems include contributions from flight software idiosyncrasies and inadequate validation of the ground procedures used to identify target stars for use by the autonomous on-board star identification algorithm. Problem fixes (some already implemented and some only proposed) are discussed. A general conclusion is drawn regarding the inherent difficulty of performing simulation tests to validate algorithms which are highly sensitive to external inputs of statistically 'rare' events.

Optimized Dual Expander Aerospike Rocket

DTIC Science & Technology

2011-03-01

manufacturability, and mission effectiveness . Despite the advantages, the bell nozzle does not optimally operate at all altitudes of flight . Furthermore...aerospike include high cooling requirements of the spike, manufacturing difficulties, and lack of historical data and flight experience [23]. Since a...Ratio; taken from Martin [4] Carlile [37] conducted a high pressure, regeneratively cooled thrust chamber experimental investigation. The experiment

Isolation of Shikimic Acid from Star Aniseed

ERIC Educational Resources Information Center

Payne, Richard; Edmonds, Michael

2005-01-01

A new undergraduate laboratory experiment suitable for demonstrating some key techniques used in natural products chemistry is described. A laboratory experiment is developed which in the process of extracting shikimic acid from star aniseed exposes students to a number of important experimental techniques.

Distinguishing thrust sequences in gravity-driven fold and thrust belts

NASA Astrophysics Data System (ADS)

Alsop, G. I.; Weinberger, R.; Marco, S.

2018-04-01

Piggyback or foreland-propagating thrust sequences, where younger thrusts develop in the footwalls of existing thrusts, are generally assumed to be the typical order of thrust development in most orogenic settings. However, overstep or 'break-back' sequences, where later thrusts develop above and in the hangingwalls of earlier thrusts, may potentially form during cessation of movement in gravity-driven mass transport deposits (MTDs). In this study, we provide a detailed outcrop-based analysis of such an overstep thrust sequence developed in an MTD in the southern Dead Sea Basin. Evidence that may be used to discriminate overstep thrusting from piggyback thrust sequences within the gravity-driven fold and thrust belt includes upright folds and forethrusts that are cut by younger overlying thrusts. Backthrusts form ideal markers that are also clearly offset and cut by overlying younger forethrusts. Portions of the basal detachment to the thrust system are folded and locally imbricated in footwall synclines below forethrust ramps, and these geometries also support an overstep sequence. However, new 'short-cut' basal detachments develop below these synclines, indicating that movement continued on the basal detachment rather than it being abandoned as in classic overstep sequences. Further evidence for 'synchronous thrusting', where movement on more than one thrust occurs at the same time, is provided by displacement patterns on sequences of thrust ramp imbricates that systematically increases downslope towards the toe of the MTD. Older thrusts that initiate downslope in the broadly overstep sequence continue to move and therefore accrue greater displacements during synchronous thrusting. Our study provides a template to help distinguish different thrust sequences in both orogenic settings and gravity-driven surficial systems, with displacement patterns potentially being imaged in seismic sections across offshore MTDs.

Formative Assessment Probes: Where Are the Stars?

ERIC Educational Resources Information Center

Keeley, Page

2011-01-01

Gazing at the night sky is a familiar experience for many elementary students. Depending on where children live, they can often look out a window and see the Moon and stars. Children may have seen the Moon and stars in television shows, movies, posters, or children's picture books. Regardless of whether they see the Moon and stars firsthand or…

Development of 90 kgf Class CAMUI Hybrid Rocket for a CanSat Experiment

NASA Astrophysics Data System (ADS)

Nagata, Harunori; Uematsu, Tsutomu; Ito, Mitsunori; Kakikura, Akihito; Kaneko, Yudai; Mori, Kazuhiro; Murai, Norikazu; Sato, Tatsuhiro; Mitsuhashi, Ryuichi; Totani, Tsuyoshi

A newly designed CAMUI hybrid rocket motor of 900 N (90 kgf) thrust class, CAMUI-90, was developed. It uses a combination of polyethylene and liquid oxygen as propellants. CAMUI hybrid rocket is an explosive-flee small rocket motor to realize a small launch system with low cost and flexibility. The motor produces a thrust of 900 N for four seconds, keeping the optimal characteristic exhaust velocity of the fuel-oxidizer combination (exceeding 1800 m/s). A main application of the CAMUI-90 motor is for a CanSat experiment. A launch vehicle employing CAMUI-90 motor, 120 mm in diameter and 3.05 m in length, accelerates a payload of 500 g to 140 m/s in four seconds and reaches to an altitude of about 1 km. The first launch of this vehicle was on December 2006.

Propulsion simulation for magnetically suspended wind tunnel models

NASA Technical Reports Server (NTRS)

Joshi, Prakash B.; Beerman, Henry P.; Chen, James; Krech, Robert H.; Lintz, Andrew L.; Rosen, David I.

1990-01-01

The feasibility of simulating propulsion-induced aerodynamic effects on scaled aircraft models in wind tunnels employing Magnetic Suspension and Balance Systems. The investigation concerned itself with techniques of generating exhaust jets of appropriate characteristics. The objectives were to: (1) define thrust and mass flow requirements of jets; (2) evaluate techniques for generating propulsive gas within volume limitations imposed by magnetically-suspended models; (3) conduct simple diagnostic experiments for techniques involving new concepts; and (4) recommend experiments for demonstration of propulsion simulation techniques. Various techniques of generating exhaust jets of appropriate characteristics were evaluated on scaled aircraft models in wind tunnels with MSBS. Four concepts of remotely-operated propulsion simulators were examined. Three conceptual designs involving innovative adaptation of convenient technologies (compressed gas cylinders, liquid, and solid propellants) were developed. The fourth innovative concept, namely, the laser-assisted thruster, which can potentially simulate both inlet and exhaust flows, was found to require very high power levels for small thrust levels.

Thrust Measurements in Ballistic Pendulum Ablative Laser Propulsion Experiments

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

Brazolin, H.; Rodrigues, N. A. S.; Minucci, M. A. S.

This paper describes a setup for thrust measurement in ablative laser propulsion experiments, based on a simple ballistic pendulum associated to an imaging system, which is being assembled at IEAv. A light aluminium pendulum holding samples is placed inside a 100 liters vacuum chamber with two optical windows: the first (in ZnSe) for the laser beam and the second (in fused quartz) for the pendulum visualization. A TEA-CO{sub 2} laser beam is focused to the samples providing ablation and transferring linear moment to the pendulum as a whole. A CCD video camera captures the oscillatory movement of the pendulum andmore » the its trajectory is obtained by image processing. By fitting the trajectory of the pendulum to a dumped sinusoidal curve is possible to obtain the amplitude of the movement which is directly related to the momentum transfered to the sample.« less

Measuring Starlight Deflection during the 2017 Eclipse: Repeating the Experiment that made Einstein Famous

NASA Astrophysics Data System (ADS)

Bruns, Donald

2016-05-01

In 1919, astronomers performed an experiment during a solar eclipse, attempting to measure the deflection of stars near the sun, in order to verify Einstein's theory of general relativity. The experiment was very difficult and the results were marginal, but the success made Albert Einstein famous around the world. Astronomers last repeated the experiment in 1973, achieving an error of 11%. In 2017, using amateur equipment and modern technology, I plan to repeat the experiment and achieve a 1% error. The best available star catalog will be used for star positions. Corrections for optical distortion and atmospheric refraction are better than 0.01 arcsec. During totality, I expect 7 or 8 measurable stars down to magnitude 9.5, based on analysis of previous eclipse measurements taken by amateurs. Reference images, taken near the sun during totality, will be used for precise calibration. Preliminary test runs performed during twilight in April 2016 and April 2017 can accurately simulate the sky conditions during totality, providing an accurate estimate of the final uncertainty.

Evaluation of various thrust calculation techniques on an F404 engine

NASA Technical Reports Server (NTRS)

Ray, Ronald J.

1990-01-01

In support of performance testing of the X-29A aircraft at the NASA-Ames, various thrust calculation techniques were developed and evaluated for use on the F404-GE-400 engine. The engine was thrust calibrated at NASA-Lewis. Results from these tests were used to correct the manufacturer's in-flight thrust program to more accurately calculate thrust for the specific test engine. Data from these tests were also used to develop an independent, simplified thrust calculation technique for real-time thrust calculation. Comparisons were also made to thrust values predicted by the engine specification model. Results indicate uninstalled gross thrust accuracies on the order of 1 to 4 percent for the various in-flight thrust methods. The various thrust calculations are described and their usage, uncertainty, and measured accuracies are explained. In addition, the advantages of a real-time thrust algorithm for flight test use and the importance of an accurate thrust calculation to the aircraft performance analysis are described. Finally, actual data obtained from flight test are presented.

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.

Numerical investigations of wake interactions of two wind turbines in tandem

NASA Astrophysics Data System (ADS)

Qian, Yaoru; Wang, Tongguang

2018-05-01

Aerodynamic performance and wake interactions between two wind turbine models under different layouts are investigated numerically using large eddy simulation in conjunction with actuator line method based on the “Blind Test” series wind tunnel experiments from Norwegian University of Science and Technology. Numerical results of the power and thrust coefficients of the two rotors and wake characteristics are in good agreement with the experimental measurements. Extended investigations emphasizing the influence of different layout arrangements on the downstream rotor performance and wake development are conducted. Results show that layout arrangements have great influence on the power and thrust prediction of the downstream turbine.

Unsteady Ejector Performance: An Experimental Investigation Using a Resonance Tube Driver

NASA Technical Reports Server (NTRS)

Wilson, Jack; Paxson, Daniel E.

2002-01-01

A statistically designed experiment to characterize thrust augmentation for unsteady ejectors has been conducted at the NASA Glenn Research Center. The variable parameters included ejector diameter, length, and nose radius. The pulsed jet driving the ejectors was produced by a shrouded resonance (or Hartmann-Sprenger) tube. In contrast to steady ejectors, an optimum ejector diameter was found, which coincided with the diameter of the vortex ring created at the pulsed jet exit. Measurements of ejector exit velocity using a hot-wire permitted evaluation of the mass augmentation ratio, which was found to correlate to thrust augmentation following a formula derived for steady ejectors.

Two-Dimensional Supersonic Nozzle Thrust Vectoring Using Staggered Ramps

NASA Astrophysics Data System (ADS)

Montes, Carlos Fernando

A novel mechanism for vectoring the thrust of a supersonic, air-breathing engine was analyzed numerically using ANSYS Fluent. The mechanism uses two asymmetrically staggered ramps; one placed at the throat, the other positioned at the exit lip of the nozzle. The nozzle was designed using published flow data, isentropic relationships, and piecewise quartic splines. The design was verified numerically and was in fair agreement with the analytical data. Using the steady-state pressure-based solver, along with the realizable kappa - epsilon turbulence model, a total of eighteen simulations were conducted: three ramp lengths at three angles, using two sets of inlet boundary conditions (non-afterburning and afterburning). The vectoring simulations showed that the afterburning flow yields a lower flow deflection distribution, shown by the calculated average deflection angle and area-weighted integrals of the distributions. The data implies that an aircraft can achieve an average thrust vectoring angle of approximately 30° in a given direction with the longest ramp length and largest ramp angle configuration. With increasing ramp angle, the static pressure across the nozzle inlet increased, causing concern for potential negative effects on the engine's turbine. The mechanism, for which a provisional patent application has been filed, will require further work to investigate the maximum possible thrust vectoring angle, including experiments.

Online Meta-data Collection and Monitoring Framework for the STAR Experiment at RHIC

NASA Astrophysics Data System (ADS)

Arkhipkin, D.; Lauret, J.; Betts, W.; Van Buren, G.

2012-12-01

The STAR Experiment further exploits scalable message-oriented model principles to achieve a high level of control over online data streams. In this paper we present an AMQP-powered Message Interface and Reliable Architecture framework (MIRA), which allows STAR to orchestrate the activities of Meta-data Collection, Monitoring, Online QA and several Run-Time and Data Acquisition system components in a very efficient manner. The very nature of the reliable message bus suggests parallel usage of multiple independent storage mechanisms for our meta-data. We describe our experience with a robust data-taking setup employing MySQL- and HyperTable-based archivers for meta-data processing. In addition, MIRA has an AJAX-enabled web GUI, which allows real-time visualisation of online process flow and detector subsystem states, and doubles as a sophisticated alarm system when combined with complex event processing engines like Esper, Borealis or Cayuga. The performance data and our planned path forward are based on our experience during the 2011-2012 running of STAR.

An air bearing system for small high speed gas turbines

NASA Astrophysics Data System (ADS)

Turner, A. B.; Davies, S. J.; Nimir, Y. L.

1994-03-01

This paper describes the second phase of an experimental program concerning the application of air bearings to small turbomachinery test rigs and small gas turbines. The first phase examined externally pressurized (EP) journal bearings, with a novel EP thrust bearing, for application to 'warm air' test rigs, and was entirely successful at rotational speeds in excess of 100,000 rpm. This second phase examined several designs of tilting pad-spiring journal bearings, one with a novel form of externally pressurized pad, but all using the original EP thrust bearing. The designs tested are described, including some oscillogram traces, for tests up to a maximum of 70,000 rpm; the most successful using a carbon pad-titanium beam spring arrangement. The thrust bearing which gave trouble-free operation throughout, is also described. The results of an original experiment to measure the 'runway speed' of a radial inflow turbine are also presented, which show that overspeeds of 58 percent above the design speed can result from free-power turbine coupling failure.

A more thorough analysis of water rockets: Moist adiabats, transient flows, and inertial forces in a soda bottle

NASA Astrophysics Data System (ADS)

Gommes, Cedric J.

2010-03-01

Although water rockets are widely used to illustrate first year physics principles, accurate measurements show that they outperform the usual textbook analysis at the beginning of the thrust phase. This paper gives a more thorough analysis of this problem. It is shown that the air expansion in the rocket is accompanied by water vapor condensation, which provides an extra thrust; the downward acceleration of water within the rocket also contributes to the thrust, an effect that is negligible in other types of rockets; the apparent gravity resulting from the acceleration of the rocket contributes as much to water ejection as does the pressure difference between the inside and outside of the rocket; and the water flow is transient, which precludes the use of Bernoulli's equation. Although none of these effects is negligible, they mostly cancel each other, and the overall accuracy of the analysis is only marginally improved. There remains a difference between theory and experiment with water rockets.

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.

Scientific activity program for 1989

NASA Astrophysics Data System (ADS)

1989-04-01

The current research projects are summarized. The research is grouped into four main directions: infrared astronomy, interplanetary media, cosmic rays and gravitational fields. The projects include instruments for the Infrared Space Observatory (ISO) satellite, problems of star formation and star evolution, Tethered Satellite System (TSS) experiment, Opera experiment, propagation of cosmic rays in the ionosphere, design of a solar neutron detector, and gravitational wave antennas experiments.

Along-strike complex geometry of subduction zones - an experimental approach

NASA Astrophysics Data System (ADS)

Midtkandal, I.; Gabrielsen, R. H.; Brun, J.-P.; Huismans, R.

2012-04-01

Recent knowledge of the great geometric and dynamic complexity insubduction zones, combined with new capacity for analogue mechanical and numerical modeling has sparked a number of studies on subduction processes. Not unexpectedly, such models reveal a complex relation between physical conditions during subduction initiation, strength profile of the subducting plate, the thermo-dynamic conditions and the subduction zones geometries. One rare geometrical complexity of subduction that remains particularly controversial, is the potential for polarity shift in subduction systems. The present experiments were therefore performed to explore the influence of the architecture, strength and strain velocity on complexities in subduction zones, focusing on along-strike variation of the collision zone. Of particular concern were the consequences for the geometry and kinematics of the transition zones between segments of contrasting subduction direction. Although the model design to some extent was inspired by the configuration along the Iberian - Eurasian suture zone, the results are also of significance for other orogens with complex along-strike geometries. The experiments were set up to explore the initial state of subduction only, and were accordingly terminated before slab subduction occurred. The model wasbuilt from layers of silicone putty and sand, tailored to simulate the assumed lithospheric geometries and strength-viscosity profiles along the plate boundary zone prior to contraction, and comprises two 'continental' plates separated by a thinner 'oceanic' plate that represents the narrow seaway. The experiment floats on a substrate of sodiumpolytungstate, representing mantle. 24 experimental runs were performed, varying the thickness (and thus strength) of the upper mantle lithosphere, as well as the strain rate. Keeping all other parameters identical for each experiment, the models were shortened by a computer-controlled jackscrew while time-lapse images were recorded. After completion, the models were saturated with water and frozen, allowing for sectioning and profile inspection. The experiments were invariably characterized by different along-strike patterns of deformation, so that three distinct structural domains could be distinguished in all cases. Model descriptions are subdivided accordingly, including domain CC, simulating a continent-continent collision, domain OC, characterized by continent-ocean-continent collision and domain T, representing the transition zone between domain CC and domain OC. The latter zone varied in width and complexity depending on the contrast in structural style developed in the two other domains; in cases where domain OC developed very differently from domain CC, the transition zone was generally wider and more complex. A typical experiment displayed the following features and strain history: In domain CC two principal thrust sheets are displayed, which obviously developed in an in-sequence foreland-directed fashion. The lowermost detachment nucleated at the base of the High Strength Lithospheric Mantle analogue, whereas the uppermost thrust was anchored within the "lower crust". The two thrusts operated in concert, the surface trace of the deepest dominating in the west, and the shallowest in the east. The kinematic development of domain CC could be subdivided into four stages, including initiation of a symmetrical anticline with a minute amplitude and situated directly above the velocity discontinuity defined by the plate contact (stage 1), contemporaneous development of the two thrusts (stage 2) and an associated asymmetrical anticline (stage 3) with a central collapse graben in the latest phase (stage 4). It is noted that the segment CC as seen in a clear majority of the experiments followed this pattern of development. In contrast, the configuration of domain OC displayed greater variation, and included north and south-directed subduction, folding, growth of pop-up-structures and triangle zones. In the "ocean crust" domain, stage 1 was characterized by the growth of a fault-propagation anticline with an E-W-oriented fold axis, ending with the surfacing of a north-vergent thrust. In stage 2, the contraction was concentrated to the south in the oceanic domain, again ending with the surfacing of a thrust, here with top-south transport. By continued movement (stage 3), the thrust fault propagated towards the east, crossing into the "continental" domain and linking with the fault systems of the segment CC. The structure of domain T is dominated by the interference of faults propagating westwards from the domain CC and eastwards from the domain OC, respectively. The zone of overlap in the experiment was significant, and its central part had the geometry of a double "crocodile structure" (sensuMeissner 1989), separating the two areas of northerly and southerly subduction. Hence, its development is less easily subdivided into stages. Reference: Meissner,R., 1989: Rupture, creep lamellae and crocodiles: happenings in the continental crust. Terra Nova, 1, 17-28.

Static Performance of Six Innovative Thrust Reverser Concepts for Subsonic Transport Applications: Summary of the NASA Langley Innovative Thrust Reverser Test Program

NASA Technical Reports Server (NTRS)

Asbury, Scott C.; Yetter, Jeffrey A.

2000-01-01

The NASA Langley Configuration Aerodynamics Branch has conducted an experimental investigation to study the static performance of innovative thrust reverser concepts applicable to high-bypass-ratio turbofan engines. Testing was conducted on a conventional separate-flow exhaust system configuration, a conventional cascade thrust reverser configuration, and six innovative thrust reverser configurations. The innovative thrust reverser configurations consisted of a cascade thrust reverser with porous fan-duct blocker, a blockerless thrust reverser, two core-mounted target thrust reversers, a multi-door crocodile thrust reverser, and a wing-mounted thrust reverser. Each of the innovative thrust reverser concepts offer potential weight savings and/or design simplifications over a conventional cascade thrust reverser design. Testing was conducted in the Jet-Exit Test Facility at NASA Langley Research Center using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0. All tests were conducted with no external flow and cold, high-pressure air was used to simulate core and fan exhaust flows. Results show that the innovative thrust reverser concepts achieved thrust reverser performance levels which, when taking into account the potential for system simplification and reduced weight, may make them competitive with, or potentially more cost effective than current state-of-the-art thrust reverser systems.

Supersonic combustion ramjet propulsion experiments in a shock tunnel

NASA Technical Reports Server (NTRS)

Paull, A.; Stalker, R. J.; Mee, D. J.

1995-01-01

Measurements have been made of the propulsive effect of supersonic combustion ramjets incorporated into a simple axisymmetric model in a free piston shock tunnel. The nominal Mach number was 6, and the stagnation enthalpy varied from 2.8 MJ kg(exp -1) to 8.5 MJ kg(exp -1). A mixture of 13 percent silane and 87 percent hydrogen was used as fuel, and experiments were conducted at equivalence ratios up to approximately 0.8. The measurements involved the axial force on the model, and were made using a stress wave force balance, which is a recently developed technique for measuring forces in shock tunnels. A net thrust was experienced up to a stagnation enthalpy of 3.7 MJ kg(exp -1), but as the stagnation enthalpy increased, an increasing net drag was recorded. pitot and static pressure measurements showed that the combustion was supersonic. The results were found to compare satisfactorily with predictions based on established theoretical models, used with some simplifying approximations. The rapid reduction of net thrust with increasing stagnation enthalpy was seen to arise from increasing precombustion temperature, showing the need to control this variable if thrust performance was to be maintained over a range of stagnation enthalpies. Both the inviscid and viscous drag were seen to be relatively insensitive to stagnation enthalpy, with the combustion chambers making a particularly significant contribution to drag. The maximum fuel specific impulse achieved in the experiments was only 175 sec., but the theory indicates that there is considerable scope for improvement on this through aerodynamic design.

Development flight tests of JetStar LFC leading-edge flight test experiment

NASA Technical Reports Server (NTRS)

Fisher, David F.; Fischer, Michael C.

1987-01-01

The overall objective of the flight tests on the JetStar aircraft was to demonstrate the effectiveness and reliability of laminar flow control under representative flight conditions. One specific objective was to obtain laminar flow on the JetStar leading-edge test articles for the design and off-design conditions. Another specific objective was to obtain operational experience on a Laminar Flow Control (LFC) leading-edge system in a simulated airline service. This included operational experience with cleaning requirements, the effect of clogging, possible foreign object damage, erosion, and the effects of ice particle and cloud encounters. Results are summarized.

Rapid deceleration mode evaluation

NASA Technical Reports Server (NTRS)

Conners, Timothy R.; Nobbs, Steven G.; Orme, John S.

1995-01-01

Aircraft with flight capability above 1.4 normally have an RPM lockup or similar feature to prevent inlet buzz that would occur at low engine airflows. This RPM lockup has the effect of holding the engine thrust level at the intermediate power (maximum non-afterburning). For aircraft such as military fighters or supersonic transports, the need exists to be able to rapidly slow from supersonic to subsonic speeds. For example, a supersonic transport that experiences a cabin decompression needs to be able to slow/descend rapidly, and this requirement may size the cabin environmental control system. For a fighter, there may be a desire to slow/descend rapidly, and while doing so to minimize fuel usage and engine exhaust temperature. Both of these needs can be aided by achieving the minimum possible overall net propulsive force. As the intermediate power thrust levels of engines increase, it becomes even more difficult to slow rapidly from supersonic speeds. Therefore, a mode of the performance seeking control (PSC) system to minimize overall propulsion system thrust has been developed and tested. The rapid deceleration mode reduces the engine airflow consistent with avoiding inlet buzz. The engine controls are trimmed to minimize the thrust produced by this reduced airflow, and moves the inlet geometry to degrade the inlet performance. As in the case of the other PSC modes, the best overall performance (in this case the least net propulsive force) requires an integrated optimization of inlet, engine, and nozzle variables. This paper presents the predicted and measured results for the supersonic minimum thrust mode, including the overall effects on aircraft deceleration.

A Kalman Filter for Mass Property and Thrust Identification of the Spin-Stabilized Magnetospheric Multiscale Formation

NASA Technical Reports Server (NTRS)

Queen, Steven Z.

2015-01-01

The Magnetospheric Multiscale (MMS) mission consists of four identically instrumented, spin-stabilized observatories, elliptically orbiting the Earth in a tetrahedron formation. For the operational success of the mission, on-board systems must be able to deliver high-precision orbital adjustment maneuvers. On MMS, this is accomplished using feedback from on-board star sensors in tandem with accelerometers whose measurements are dynamically corrected for errors associated with a spinning platform. In order to determine the required corrections to the measured acceleration, precise estimates of attitude, rate, and mass-properties are necessary. To this end, both an on-board and ground-based Multiplicative Extended Kalman Filter (MEKF) were formulated and implemented in order to estimate the dynamic and quasi-static properties of the spacecraft.

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.

Medium-frequency impulsive-thrust-activated liquid hydrogen reorientation with Geyser

NASA Technical Reports Server (NTRS)

Hung, R. J.; Shyu, K. L.

1992-01-01

Efficient technique are studied for accomplishing propellant resettling through the minimization of propellant usage through impulsive thrust. A comparison between the use of constant-thrust and impulsive-thrust accelerations for the activation of propellant resettlement shows that impulsive thrust is superior to constant thrust for liquid reorientation in a reduced-gravity environment. This study shows that when impulsive thrust with 0.1-1.0-, and 10-Hz frequencies for liquid-fill levels in the range between 30-80 percent is considered, the selection of 1.0-Hz-frequency impulsive thrust over the other frequency ranges of impulsive thrust is the optimum. Characteristics of the slosh waves excited during the course of 1.0-Hz-frequency impulsive-thrust liquid reorientation were also analyzed.

Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate

PubMed Central

Reed, William R.; Cao, Dong-Yuan; Long, Cynthia R.; Kawchuk, Gregory N.; Pickar, Joel G.

2013-01-01

High velocity low amplitude spinal manipulation (HVLA-SM) is used frequently to treat musculoskeletal complaints. Little is known about the intervention's biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20–30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages. PMID:23401713

Projectile Combustion Effects on Ram Accelerator Performance

NASA Astrophysics Data System (ADS)

Chitale, Saarth Anjali

University of Washington Abstract Projectile Combustion Effects on Ram Accelerator Performance Saarth Anjali Chitale Chair of the Supervisory Committee: Prof. Carl Knowlen William E. Boeing Department of Aeronautics and Astronautics The ram accelerator facility at the University of Washington is used to propel projectiles at supersonic velocities. This concept is similar to an air-breathing ramjet engine in that sub-caliber projectiles, shaped like the ramjet engine center-body, are shot through smooth-bore steel-walled tubes having an internal diameter of 38 mm. The ram accelerator propulsive cycles operate between Mach 2 to 10 and have the potential to accelerate projectile to velocities greater than 8 km/s. The theoretical thrust versus Mach number characteristics can be obtained using knowledge of gas dynamics and thermodynamics that goes into the design of the ram accelerator. The corresponding velocity versus distance profiles obtained from the test runs at the University of Washington, however, are often not consistent with the theoretical predictions after the projectiles reach in-tube Mach numbers greater than 4. The experimental velocities are typically greater than the expected theoretical predictions; which has led to the proposition that the combustion process may be moving up onto the projectile. An alternative explanation for higher than predicted thrust, which is explored here, is that the performance differences can be attributed to the ablation of the projectile body which results in molten metal being added to the flow of the gaseous combustible mixture around the projectile. This molten metal is assumed to mix uniformly and react with the gaseous propellant; thereby enhancing the propellant energy release and altering the predicted thrust-Mach characteristics. This theory predicts at what Mach number the projectile will first experience enhanced thrust and the corresponding velocity-distance profile. Preliminary results are in good agreement with projectiles operating in methane/oxygen/nitrogen propellants. Effects of projectile surface to volume ratio are also explored by applying the model to experimental results from smaller (Tohoku University, 25-mm-bore) and larger (Institute of Saint-Louis 90-mm-bore) bore ram accelerators. Due to lower surface-to-volume ratio, large diameter projectiles are predicted to need to reach higher Mach numbers than smaller diameter projectiles before thrust enhancement due to metal ablation and burning would be experienced. This proposition was supported by published experimental data. The theoretical modeling of projectile ablation, metal combustion, and subsequent ram accelerator thrust characteristics are presented along comparisons to experiments from three different sized ram accelerator facilities.

Precision star-tracking telescope

NASA Technical Reports Server (NTRS)

Fairbank, W. M.; Everitt, C. W. F.

1972-01-01

The design, construction, and preliminary testing of a new high accuracy star tracking telescope for the laboratory model of the Stanford gyro relativity experiment are described. The function of the telescope in the final flight experiment is to define (by reference to a suitable star) a direction in space for comparison with the relativistic precession of a group of gyroscopes. The design of the telescope has been strongly affected by designs for other portions of the overall experiments, for example the gyroscopes, the attitude control system of the satellite, and the instrumentation system used in processing relativity data. Main goals for the star tracker are: (1) independent readout of angular position in two planes; (2) absolute null stability over a one year period of mechanical parts; (3) readout linear to 0.001 arc-seconds over + or - 0.05 arc-second; (4) noise performance leading to a resolution of 0.05 arc-second in 0.1 second observation time of the chosen reference star; and (5) provision for automatic gain control capable of matching the gains of the gyroscopes and telescope readouts to 1% or better.

Rise of the First Super-Massive Stars

NASA Astrophysics Data System (ADS)

Regan, John A.; Downes, Turlough P.

2018-05-01

We use high resolution adaptive mesh refinement simulations to model the formation of massive metal-free stars in the early Universe. By applying Lyman-Werner (LW) backgrounds of 100 J21 and 1000 J21 respectively we construct environments conducive to the formation of massive stars. We find that only in the case of the higher LW backgrounds are super-critical accretion rates realised that are necessary for super-massive star (SMS) formation. Mild fragmentation is observed for both backgrounds. Violent dynamical interactions between the stars that form in the more massive halo formed (1000 J21 background) results in the eventual expulsion of the two most massive stars from the halo. In the smaller mass halo (100 J21 background) mergers of stars occur before any multibody interactions and a single massive Pop III star is left at the centre of the halo at the end of our simulation. Feedback from the very massive Pop III stars is not effective in generating a large HII region with ionising photons absorbed within a few thousand AU of the star. In all cases a massive black hole seed is the expected final fate of the most massive objects. The seed of the massive Pop III star which remained at the centre of the less massive halo experiences steady accretion rates of almost 10-2M_{⊙}/yr and if these rates continue could potentially experience super-Eddington accretion rates in the immediate aftermath of collapsing into a black hole.

First results of a polychromatic artificial sodium star for the correction of tilt

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

Friedman, H.; Foy, R..; Tallon, M.

1996-03-06

This paper presents the first results of a joint experiment carried out at Lawrence Livermore National Laboratory during January, 1996. Laser and optical systems were tested to provide a polychromatic artificial sodium star for the correction of tilt. This paper presents the results of that experiment.

Skylab-3 Mission Onboard Photograph - Astronaut Bean working on Experiment S019

NASA Technical Reports Server (NTRS)

1973-01-01

This Skylab-3 mission onboard photograph shows Astronaut Alan Bean operating the Ultraviolet (UV) Stellar Astronomy experiment (S019) in the Skylab Airlock Module. The S019, a camera with a prism for UV star photography, studied the UV spectra of early-type stars and galaxies.

On the origin of high-velocity runaway stars

NASA Astrophysics Data System (ADS)

Gvaramadze, Vasilii V.; Gualandris, Alessia; Portegies Zwart, Simon

2009-06-01

We explore the hypothesis that some high-velocity runaway stars attain their peculiar velocities in the course of exchange encounters between hard massive binaries and a very massive star (either an ordinary 50-100Msolar star or a more massive one, formed through runaway mergers of ordinary stars in the core of a young massive star cluster). In this process, one of the binary components becomes gravitationally bound to the very massive star, while the second one is ejected, sometimes with a high speed. We performed three-body scattering experiments and found that early B-type stars (the progenitors of the majority of neutron stars) can be ejected with velocities of >~200-400kms-1 (typical of pulsars), while 3-4Msolar stars can attain velocities of >~300-400kms-1 (typical of the bound population of halo late B-type stars). We also found that the ejected stars can occasionally attain velocities exceeding the Milky Ways's escape velocity.

Control of syntectonic erosion and sedimentation on kinematic evolution of a multidecollement fold and thrust zone: Analogue modeling of folding in the southern subandean of Bolivia

NASA Astrophysics Data System (ADS)

Darnault, Romain; Callot, Jean-Paul; Ballard, Jean-François; Fraisse, Guillaume; Mengus, Jean-Marie; Ringenbach, Jean-Claude

2016-08-01

Several analogue modeling studies have been conducted during the past fifteen years with the aim to discuss the effects of sedimentation and erosion on Foreland Fold and Thrust Belt, among which a few have analyzed these processes at kilometric scale (Malavieille et al., 1993; Nalpas et al., 1999; Barrier et al., 2002; Pichot and Nalpas, 2009). The influence of syn-deformation sedimentation and erosion on the structural evolution of FFTB has been clearly demonstrated. Here, we propose to go further in this approach by the study of a more complex system with a double decollement level. The natural study case is the Bolivian sub-Andean thrust and fold belt, which present all the required criteria, such as the double decollement level. A set of analogue models performed under a CT-scan have been used to test the influence of several parameters on a fold and thrust belt system, among which: (i) the spatial variation of the sediment input, (ii) the spatial variation of the erosion rate, (iii) the relative distribution of sedimentation between foreland and hinterland. These experiments led to the following observations: 1. The upper decollement level acts as a decoupling level in case of increased sedimentation rate: it results in the verticalization of the shallower part (above the upper decollement level), while the deeper parts are not impacted. 2. Similarly, the increase of the erosion rate involves the uplift of the deeper part (below the upper decollement level), whereas the shallower parts are not impacted. 3. A high sedimentation rate in the foreland involves a fault and fold vergence reversal, followed by a back-thrusting of the shallower part. 4. A high sedimentation rate in the hinterland favours thrust development toward the foreland in the shallower parts.

Characterization of the non axial thrust generated by large solid propellant rocket motors in three axis stabilized ascent

NASA Technical Reports Server (NTRS)

Kosmann, W. J.; Dionne, E. R.; Klemetson, R. W.

1978-01-01

Nonaxial thrusts produced by solid rocket motors during three-axis stabilized attitude control have been determined from ascent experience on twenty three Burner II, Burner IIA and Block 5D-1 upper stage vehicles. A data base representing four different rocket motor designs (three spherical and one extended spherical) totaling twenty five three-axis stabilized firings is generated. Solid rocket motor time-varying resultant and lateral side force vector magnitudes, directions and total impulses, and roll torque couple magnitudes, directions, and total impulses are tabulated in the appendix. Population means and three sigma deviations are plotted. Existing applicable ground test side force and roll torque magnitudes and total impulses are evaluated and compared to the above experience data base. Within the spherical motor population, the selected AEDC ground test data consistently underestimated experienced motor side forces, roll torques and total impulses. Within the extended spherical motor population, the selected AEDC test data predicted experienced motor side forces, roll torques, and total impulses, with surprising accuracy considering the very small size of the test and experience populations.

Uncertainty of in-flight thrust determination

NASA Technical Reports Server (NTRS)

Abernethy, Robert B.; Adams, Gary R.; Steurer, John W.; Ascough, John C.; Baer-Riedhart, Jennifer L.; Balkcom, George H.; Biesiadny, Thomas

1986-01-01

Methods for estimating the measurement error or uncertainty of in-flight thrust determination in aircraft employing conventional turbofan/turbojet engines are reviewed. While the term 'in-flight thrust determination' is used synonymously with 'in-flight thrust measurement', in-flight thrust is not directly measured but is determined or calculated using mathematical modeling relationships between in-flight thrust and various direct measurements of physical quantities. The in-flight thrust determination process incorporates both ground testing and flight testing. The present text is divided into the following categories: measurement uncertainty methodoogy and in-flight thrust measurent processes.

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

Was Himalayan normal faulting triggered by initiation of the Ramgarh-Munsiari Thrust?

USGS Publications Warehouse

Robinson, Delores M.; Pearson, Ofori N.

2013-01-01

The Ramgarh–Munsiari thrust is a major orogen-scale fault that extends for more than 1,500 km along strike in the Himalayan fold-thrust belt. The fault can be traced along the Himalayan arc from Himachal Pradesh, India, in the west to eastern Bhutan. The fault is located within the Lesser Himalayan tectonostratigraphic zone, and it translated Paleoproterozoic Lesser Himalayan rocks more than 100 km toward the foreland. The Ramgarh–Munsiari thrust is always located in the proximal footwall of the Main Central thrust. Northern exposures (toward the hinterland) of the thrust sheet occur in the footwall of the Main Central thrust at the base of the high Himalaya, and southern exposures (toward the foreland) occur between the Main Boundary thrust and Greater Himalayan klippen. Although the metamorphic grade of rocks within the Ramgarh–Munsiari thrust sheet is not significantly different from that of Greater Himalayan rock in the hanging wall of the overlying Main Central thrust sheet, the tectonostratigraphic origin of the two different thrust sheets is markedly different. The Ramgarh–Munsiari thrust became active in early Miocene time and acted as the roof thrust for a duplex system within Lesser Himalayan rocks. The process of slip transfer from the Main Central thrust to the Ramgarh–Munsiari thrust in early Miocene time and subsequent development of the Lesser Himalayan duplex may have played a role in triggering normal faulting along the South Tibetan Detachment system.

Catalog of far-ultraviolet objective-prism spectrophotometry: Skylab experiment S-019, ultraviolet steller astronomy

NASA Technical Reports Server (NTRS)

Henize, K. G.; Wray, J. D.; Parsons, S. B.; Benedict, G. F.

1979-01-01

Ultraviolet stellar spectra in the wavelength region from 1300 to 5000 A (130 to 500) were photographed during the three manned Skylab missions using a 15 cm aperture objective-prism telescope. The prismatic dispersion varied from 58 A mm/1 at 1400 A to 1600 A mm/1 at 3000 A. Approximately 1000 spectra representing 500 stars were measured and reduced to observed fluxes. About 100 stars show absorption lines of Si IV, C IV, or C II. Numerous line features are also recorded in supergiant stars, shell stars, A and F stars, and Wolf-Rayet stars. Most of the stars in the catalog are of spectral class B, with a number of O and A type stars and a sampling of WC, WN, F and C type stars. Spectrophotometric results are tabulated for these 500 stars.

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.

The Dual-channel Extreme Ultraviolet Continuum Experiment: Sounding Rocket EUV Observations of Local B Stars to Determine Their Potential for Supplying Intergalactic Ionizing Radiation

NASA Astrophysics Data System (ADS)

Erickson, Nicholas; Green, James C.; France, Kevin; Stocke, John T.; Nell, Nicholas

2018-06-01

We describe the scientific motivation and technical development of the Dual-channel Extreme Ultraviolet Continuum Experiment (DEUCE). DEUCE is a sounding rocket payload designed to obtain the first flux-calibrated spectra of two nearby B stars in the EUV 650-1150Å bandpass. This measurement will help in understanding the ionizing flux output of hot B stars, calibrating stellar models and commenting on the potential contribution of such stars to reionization. DEUCE consists of a grazing incidence Wolter II telescope, a normal incidence holographic grating, and the largest (8” x 8”) microchannel plate detector ever flown in space, covering the 650-1150Å band in medium and low resolution channels. DEUCE will launch on December 1, 2018 as NASA/CU sounding rocket mission 36.331 UG, observing Epsilon Canis Majoris, a B2 II star.

The Optical Gravitational Lensing Experiment: catalogue of stellar proper motions in the OGLE-II Galactic bulge fields

NASA Astrophysics Data System (ADS)

Sumi, T.; Wu, X.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Woźniak, P.; Żebruń, K.; Szewczyk, O.; Wyrzykowski, Ł.

2004-03-01

We present a proper-motion (μ) catalogue of 5 080 236 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge (GB) fields, covering a range of -11° < l < 11° and -6° < b < 3°, the total area close to 11 deg2. The proper-motion measurements are based on 138-555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11 < I < 18 mag. In particular, the catalogue includes red clump giants and red giants in the GB, and main-sequence stars in the Galactic disc. The proper motions up to μ= 500 mas yr-1 were measured with a mean accuracy of 0.8-3.5 mas yr-1, depending on the brightness of a star. This catalogue may be useful for studying the kinematics of stars in the GB and the Galactic disc.

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

Effect of a rough surface on the aerodynamic characteristics of a two-bladed wind-powered engine with cylindrical blades

NASA Astrophysics Data System (ADS)

Tanasheva, N. K.; Kunakbaev, T. O.; Dyusembaeva, A. N.; Shuyushbayeva, N. N.; Damekova, S. K.

2017-11-01

We have reported the results of experiments on determining the drag coefficient and the thrust coefficient of a two-bladed wind-powered engine based on the Magnus effect with rotating rough cylinders in the range of air flow velocity of 4-10 m/s (Re = 26800-90000) for a constant rotation number of a cylindrical blade about its own axis. The results show that an increase in the Reynolds number reduces the drag coefficient and the thrust coefficient. The extent of the influence of the relative roughness on the aerodynamic characteristics of the two-bladed wind-powered engine has been experimentally established.

Modifications to the nozzle test chamber to extend nozzle static-test capability

NASA Technical Reports Server (NTRS)

Keyes, J. W.

1985-01-01

The nozzle test chamber was modified to provide a high-pressure-ratio nozzle static-test capability. Experiments were conducted to determine the range of the ratio of nozzle total pressure to chamber pressure and to make direct nozzle thrust measurements using a three-component strain-gage force balance. Pressure ratios from 3 to 285 were measured with several axisymmetric nozzles at a nozzle total pressure of 15 to 190 psia. Devices for measuring system mass flow were calibrated using standard axisymmetric convergent choked nozzles. System mass-flow rates up to 10 lbm/sec are measured. The measured thrust results of these nozzles are in good agreement with one-dimensional theoretical predictions for convergent nozzles.

Inductive storage for quasi-steady MPD thrusters

NASA Technical Reports Server (NTRS)

Clark, K. E.

1978-01-01

Experiments in which a quasi-steady MPD thruster is driven by a large inductor demonstrate the feasibility of using inductive energy storage to couple an intermittent high power plasma thruster to a lower power steady state supply, such as a thermionic converter. Switching between inductor charging and MPD thrusting phases of the current cycle occurs smoothly, with the voltage spike generated during switching sufficient to initiate the arc discharge in the thruster without an auxiliary starting circuit. Further, the current waveforms delivered by the inductor are of a shape suitable for the quasi-steady thrusting process, and they agree with analytical estimates, indicating that the interaction between the thruster impedance and the inductive source is dynamically stable.

Experiment Pamir-3. Coplanar emission of high energy gamma-quanta at interaction of hadrons with nuclei of air atoms at energies above 10 to the 7th power GeV

NASA Technical Reports Server (NTRS)

Asatiani, T. L.; Genina, L. E.; Zatsepin, G. T.

1985-01-01

A systematic analysis of large gamma families, detected in X-ray emulsion chambers, cases of multicore halos have been observed, and among them five events in which the halo is divided into three of four separate cores with their alignment observed in the target diagram (coplanarity of axes of corresponding electron photon cascades). The halo alignment (tendency to the straight line) leads to the aximuthal asymmetry (thrust). The analysis of lateral and momentum distributions of particles in these families shows that they also have thrust that correlates with the direction of the halo core alignment.

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.

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.

Flux-Level Transit Injection Experiments with NASA Pleiades Supercomputer

NASA Astrophysics Data System (ADS)

Li, Jie; Burke, Christopher J.; Catanzarite, Joseph; Seader, Shawn; Haas, Michael R.; Batalha, Natalie; Henze, Christopher; Christiansen, Jessie; Kepler Project, NASA Advanced Supercomputing Division

2016-06-01

Flux-Level Transit Injection (FLTI) experiments are executed with NASA's Pleiades supercomputer for the Kepler Mission. The latest release (9.3, January 2016) of the Kepler Science Operations Center Pipeline is used in the FLTI experiments. Their purpose is to validate the Analytic Completeness Model (ACM), which can be computed for all Kepler target stars, thereby enabling exoplanet occurrence rate studies. Pleiades, a facility of NASA's Advanced Supercomputing Division, is one of the world's most powerful supercomputers and represents NASA's state-of-the-art technology. We discuss the details of implementing the FLTI experiments on the Pleiades supercomputer. For example, taking into account that ~16 injections are generated by one core of the Pleiades processors in an hour, the “shallow” FLTI experiment, in which ~2000 injections are required per target star, can be done for 16% of all Kepler target stars in about 200 hours. Stripping down the transit search to bare bones, i.e. only searching adjacent high/low periods at high/low pulse durations, makes the computationally intensive FLTI experiments affordable. The design of the FLTI experiments and the analysis of the resulting data are presented in “Validating an Analytic Completeness Model for Kepler Target Stars Based on Flux-level Transit Injection Experiments” by Catanzarite et al. (#2494058).Kepler was selected as the 10th mission of the Discovery Program. Funding for the Kepler Mission has been provided by the NASA Science Mission Directorate.

The thrust belt in Southwest Montana and east-central Idaho

USGS Publications Warehouse

Ruppel, Edward T.; Lopez, David A.

1984-01-01

The leading edge of the Cordilleran fold and thrust in southwest Montana appears to be a continuation of the edge of the Wyoming thrust belt, projected northward beneath the Snake River Plain. Trces of the thrust faults that form the leading edge of the thrust belts are mostly concealed, but stratigraphic and structural evidence suggests that the belt enters Montana near the middle of the Centennial Mountains, continues west along the Red Rock River valley, and swings north into the Highland Mountains near Butte. The thrust belt in southwest Montana and east-central Idaho includes at least two major plates -- the Medicine Lodge and Grasshopper thrust plates -- each of which contains a distinctive sequence of rocks, different in facies and structural style from those of the cratonic region east of the thrust belt. The thrust plates are characterized by persuasive, open to tight and locally overturned folds, and imbricate thrust faults, structural styles unusual in Phanerozoic cratonic rocks. The basal decollement zones of the plates are composed of intensely sheared, crushed, brecciated, and mylonitized rocks, the decollement at the base of the Medicine Lodge plate is as much as 300 meters thick. The Medicine Lodge and Grasshopper thrust plates are fringed on the east by a 10- to 50-kilometer-wide zone of tightly folded rocks cut by imbricate thrust fauls, a zone that forms the eastern margin of the thrust belt in southwest Montana. The frontal fold and thrust zone includes rocks that are similar to those of the craton, even though they differ in details of thickness, composition, or stratigraphic sequence. The zone is interpreted to be one of terminal folding and thrusting in cratonic rocks overridden by the major thrust plates from farther west. The cratonic rocks were drape-folded over rising basement blocks that formed a foreland bulge in front of the thrust belt. The basement blocks are bounded by steep faults of Proterozoic ancestry, which also moved as tear faults during thrusting, and seem to have controlled the curving patterns of salients and reentrants at the leading edge of the thrust belt. Radiometric and stratiographic evidence shows that the thrust belt was in its present position by about 75 million year go.

Dying to be famous: retrospective cohort study of rock and pop star mortality and its association with adverse childhood experiences

PubMed Central

Bellis, Mark A; Hughes, Karen; Sharples, Olivia; Hennell, Tom; Hardcastle, Katherine A

2012-01-01

Objectives Rock and pop fame is associated with risk taking, substance use and premature mortality. We examine relationships between fame and premature mortality and test how such relationships vary with type of performer (eg, solo or band member) and nationality and whether cause of death is linked with prefame (adverse childhood) experiences. Design A retrospective cohort analysis based on biographical data. An actuarial methodology compares postfame mortality to matched general populations. Cox survival and logistic regression techniques examine risk and protective factors for survival and links between adverse childhood experiences and cause of death, respectively. Setting North America and Europe. Participants 1489 rock and pop stars reaching fame between 1956 and 2006. Outcomes Stars’ postfame mortality relative to age-, sex- and ethnicity-matched populations (USA and UK); variations in survival with performer type, and in cause of mortality with exposure to adverse childhood experiences. Results Rock/pop star mortality increases relative to the general population with time since fame. Increases are greater in North American stars and those with solo careers. Relative mortality begins to recover 25 years after fame in European but not North American stars. Those reaching fame from 1980 onwards have better survival rates. For deceased stars, cause of death was more likely to be substance use or risk-related in those with more adverse childhood experiences. Conclusions Relationships between fame and mortality vary with performers’ characteristics. Adverse experiences in early life may leave some predisposed to health-damaging behaviours, with fame and extreme wealth providing greater opportunities to engage in risk-taking. Millions of youths wish to emulate their icons. It is important they recognise that substance use and risk-taking may be rooted in childhood adversity rather than seeing them as symbols of success. PMID:23253869

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.

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.

Measurement of hydrodynamic force generation by swimming dolphins using bubble DPIV.

PubMed

Fish, Frank E; Legac, Paul; Williams, Terrie M; Wei, Timothy

2014-01-15

Attempts to measure the propulsive forces produced by swimming dolphins have been limited. Previous uses of computational hydrodynamic models and gliding experiments have provided estimates of thrust production by dolphins, but these were indirect tests that relied on various assumptions. The thrust produced by two actively swimming bottlenose dolphins (Tursiops truncatus) was directly measured using digital particle image velocimetry (DPIV). For dolphins swimming in a large outdoor pool, the DPIV method used illuminated microbubbles that were generated in a narrow sheet from a finely porous hose and a compressed air source. The movement of the bubbles was tracked with a high-speed video camera. Dolphins swam at speeds of 0.7 to 3.4 m s(-1) within the bubble sheet oriented along the midsagittal plane of the animal. The wake of the dolphin was visualized as the microbubbles were displaced because of the action of the propulsive flukes and jet flow. The oscillations of the dolphin flukes were shown to generate strong vortices in the wake. Thrust production was measured from the vortex strength through the Kutta-Joukowski theorem of aerodynamics. The dolphins generated up to 700 N during small amplitude swimming and up to 1468 N during large amplitude starts. The results of this study demonstrated that bubble DPIV can be used effectively to measure the thrust produced by large-bodied dolphins.

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

A hybrid method for accurate star tracking using star sensor and gyros.

PubMed

Lu, Jiazhen; Yang, Lie; Zhang, Hao

2017-10-01

Star tracking is the primary operating mode of star sensors. To improve tracking accuracy and efficiency, a hybrid method using a star sensor and gyroscopes is proposed in this study. In this method, the dynamic conditions of an aircraft are determined first by the estimated angular acceleration. Under low dynamic conditions, the star sensor is used to measure the star vector and the vector difference method is adopted to estimate the current angular velocity. Under high dynamic conditions, the angular velocity is obtained by the calibrated gyros. The star position is predicted based on the estimated angular velocity and calibrated gyros using the star vector measurements. The results of the semi-physical experiment show that this hybrid method is accurate and feasible. In contrast with the star vector difference and gyro-assisted methods, the star position prediction result of the hybrid method is verified to be more accurate in two different cases under the given random noise of the star centroid.

A Multidisciplinary Performance Analysis of a Lifting-Body Single-Stage-to-Orbit Vehicle

NASA Technical Reports Server (NTRS)

Tartabini, Paul V.; Lepsch, Roger A.; Korte, J. J.; Wurster, Kathryn E.

2000-01-01

Lockheed Martin Skunk Works (LMSW) is currently developing a single-stage-to-orbit reusable launch vehicle called VentureStar(TM) A team at NASA Langley Research Center participated with LMSW in the screening and evaluation of a number of early VentureStar(TM) configurations. The performance analyses that supported these initial studies were conducted to assess the effect of a lifting body shape, linear aerospike engine and metallic thermal protection system (TPS) on the weight and performance of the vehicle. These performance studies were performed in a multidisciplinary fashion that indirectly linked the trajectory optimization with weight estimation and aerothermal analysis tools. This approach was necessary to develop optimized ascent and entry trajectories that met all vehicle design constraints. Significant improvements in ascent performance were achieved when the vehicle flew a lifting trajectory and varied the engine mixture ratio during flight. Also, a considerable reduction in empty weight was possible by adjusting the total oxidizer-to-fuel and liftoff thrust-to-weight ratios. However, the optimal ascent flight profile had to be altered to ensure that the vehicle could be trimmed in pitch using only the flow diverting capability of the aerospike engine. Likewise, the optimal entry trajectory had to be tailored to meet TPS heating rate and transition constraints while satisfying a crossrange requirement.

Measurement of Impulsive Thrust from a Closed Radio Frequency Cavity in Vacuum

NASA Technical Reports Server (NTRS)

White, Harold; March, Paul; Lawrence, James; Vera, Jerry; Sylvester, Andre; Brady, David; Bailey, Paul

2016-01-01

A vacuum test campaign evaluating the impulsive thrust performance of a tapered RF test article excited in the TM212 mode at 1,937 megahertz (MHz) has been completed. The test campaign consisted of a forward thrust phase and reverse thrust phase at less than 8 x 10(exp -6) Torr vacuum with power scans at 40 watts, 60 watts, and 80 watts. The test campaign included a null thrust test effort to identify any mundane sources of impulsive thrust, however none were identified. Thrust data from forward, reverse, and null suggests that the system is consistently performing with a thrust to power ratio of 1.2 +/- 0.1 mN/kW.

Quiet Clean Short-Haul Experimental Engine (QCSEE) acoustic and aerodynamic tests on a scale model over-the-wing thrust reverser and forward thrust nozzle

NASA Technical Reports Server (NTRS)

Stimpert, D. L.

1978-01-01

An acoustic and aerodynamic test program was conducted on a 1/6.25 scale model of the Quiet, Clean, Short-Haul Experimental Engine (QCSEE) forward thrust over-the-wing (OTW) nozzle and OTW thrust reverser. In reverse thrust, the effect of reverser geometry was studied by parametric variations in blocker spacing, blocker height, lip angle, and lip length. Forward thrust nozzle tests determined the jet noise levels of the cruise and takeoff nozzles, the effect of opening side doors to achieve takeoff thrust, and scrubbing noise of the cruise and takeoff jet on a simulated wing surface. Velocity profiles are presented for both forward and reverse thrust nozzles. An estimate of the reverse thrust was made utilizing the measured centerline turning angle.

Class-Size Policy: The STAR Experiment and Related Class-Size Studies. NCPEA Policy Brief. Volume 1, Number 2

ERIC Educational Resources Information Center

Achilles, Charles M.

2012-01-01

This brief summarizes findings on class size from over 25 years of work on the Tennessee Student Teacher Achievement Ratio (STAR) randomized, longitudinal experiment, and other Class-Size Reduction (CSR) studies throughout the United States, Australia, Hong Kong, Sweden, Great Britain, and elsewhere. The brief concludes with recommendations. The…

Recent Upgrades at the Safety and Tritium Applied Research Facility

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

Cadwallader, Lee Charles; Merrill, Brad Johnson; Stewart, Dean Andrew

This paper gives a brief overview of the Safety and Tritium Applied Research (STAR) facility operated by the Fusion Safety Program (FSP) at the Idaho National Laboratory (INL). FSP researchers use the STAR facility to carry out experiments in tritium permeation and retention in various fusion materials, including wall armor tile materials. FSP researchers also perform other experimentation as well to support safety assessment in fusion development. This lab, in its present two-building configuration, has been in operation for over ten years. The main experiments at STAR are briefly described. This paper discusses recent work to enhance personnel safety atmore » the facility. The STAR facility is a Department of Energy less than hazard category 3 facility; the personnel safety approach calls for ventilation and tritium monitoring for radiation protection. The tritium areas of STAR have about 4 to 12 air changes per hour, with air flow being once through and then routed to the facility vent stack. Additional radiation monitoring has been installed to read the laboratory room air where experiments with tritium are conducted. These ion chambers and bubblers are used to verify that no significant tritium concentrations are present in the experiment rooms. Standby electrical power has been added to the facility exhaust blower so that proper ventilation will now operate during commercial power outages as well as the real-time tritium air monitors.« less

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.

Experimental and analytical studies of flow through a ventral and axial exhaust nozzle system for STOVL aircraft

NASA Technical Reports Server (NTRS)

Esker, Barbara S.; Debonis, James R.

1991-01-01

Flow through a combined ventral and axial exhaust nozzle system was studied experimentally and analytically. The work is part of an ongoing propulsion technology effort at NASA Lewis Research Center for short takeoff, vertical landing (STOVL) aircraft. The experimental investigation was done on the NASA Lewis Powered Lift Facility. The experiment consisted of performance testing over a range of tailpipe pressure ratios from 1 to 3.2 and flow visualization. The analytical investigation consisted of modeling the same configuration and solving for the flow using the PARC3D computational fluid dynamics program. The comparison of experimental and analytical results was very good. The ventral nozzle performance coefficients obtained from both the experimental and analytical studies agreed within 1.2 percent. The net horizontal thrust of the nozzle system contained a significant reverse thrust component created by the flow overturning in the ventral duct. This component resulted in a low net horizontal thrust coefficient. The experimental and analytical studies showed very good agreement in the internal flow patterns.

A comprehensive cold gas performance study of the Pocket Rocket radiofrequency electrothermal microthruster

NASA Astrophysics Data System (ADS)

Ho, Teck Seng; Charles, Christine; Boswell, Roderick W.

2016-12-01

This paper presents computational fluid dynamics simulations of the cold gas operation of Pocket Rocket and Mini Pocket Rocket radiofrequency electrothermal microthrusters, replicating experiments performed in both sub-Torr and vacuum environments. This work takes advantage of flow velocity choking to circumvent the invalidity of modelling vacuum regions within a CFD simulation, while still preserving the accuracy of the desired results in the internal regions of the microthrusters. Simulated results of the plenum stagnation pressure is in precise agreement with experimental measurements when slip boundary conditions with the correct tangential momentum accommodation coefficients for each gas are used. Thrust and specific impulse is calculated by integrating the flow profiles at the exit of the microthrusters, and are in good agreement with experimental pendulum thrust balance measurements and theoretical expectations. For low thrust conditions where experimental instruments are not sufficiently sensitive, these cold gas simulations provide additional data points against which experimental results can be verified and extrapolated. The cold gas simulations presented in this paper will be used as a benchmark to compare with future plasma simulations of the Pocket Rocket microthruster.

STAR -Space Time Asymmetry Research

NASA Astrophysics Data System (ADS)

van Zoest, Tim; Braxmaier, Claus; Schuldt, Thilo; Allab, Mohammed; Theil, Stephan; Pelivan, Ivanka; Herrmann, Sven; Lümmerzahl, Claus; Peters, Achim; Mühle, Katharina; Wicht, Andreas; Nagel, Moritz; Kovalchuk, Evgeny; Düringshoff, Klaus; Dittus, Hansjürg

STAR is a proposed satellite mission that aims for significantly improved tests of fundamental space-time symmetry and the foundations of special and general relativity. In total STAR comprises a series of five subsequent missions. The STAR1 mission will measure the constancy of the speed of light to one part in 1019 and derive the Kennedy Thorndike (KT) coefficient of the Mansouri-Sexl test theory to 7x10-10 . The KT experiment will be performed by compar-ison of an iodine standard with a highly stable cavity made from ultra low expansion (ULE) ceramics. With an orbital velocity of 7 km/s the sensitivity to a boost dependent violation of Lorentz invariance as modeled by the KT term in the Mansouri Sexl test theory or a Lorentz violating extension of the standard model (SME) will be significantly enhanced as compared to Earth based experiments. The low noise space environment will additionally enhance the measurement precision such that an overall improvement by a factor of 400 over current Earth based experiments is expected.

Flow Measurements Using Particle Image Velocimetry in the Ultra Compact Combustor

DTIC Science & Technology

2009-12-01

addition effectively increases the flow velocity resulting in increased thrust. The afterburning cycle is much less efficient than the Brayton cycle used...31. Rekab, K., & Shaikh, M., Statistical Design of Experiments with Engineering Applications, Florida: CRC Press, Taylor & Francis Group, 2005

Earthquake in Hindu Kush Region, Afghanistan

NASA Image and Video Library

2015-10-27

On Oct. 26, 2015, NASA Terra spacecraft acquired this image of northeastern Afghanistan where a magnitude 7.5 earthquake struck the Hindu Kush region. The earthquake's epicenter was at a depth of 130 miles (210 kilometers), on a probable shallowly dipping thrust fault. At this location, the Indian subcontinent moves northward and collides with Eurasia, subducting under the Asian continent, and raising the highest mountains in the world. This type of earthquake is common in the area: a similar earthquake occurred 13 years ago about 12 miles (20 kilometers) away. This perspective image from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) instrument on NASA's Terra spacecraft, looking southwest, shows the hypocenter with a star. The image was acquired July 8, 2015, and is located near 36.4 degrees north, 70.7 degrees east. http://photojournal.jpl.nasa.gov/catalog/PIA20035

Flight-determined benefits of integrated flight-propulsion control systems

NASA Technical Reports Server (NTRS)

Stewart, James F.; Burcham, Frank W., Jr.; Gatlin, Donald H.

1992-01-01

Over the last two decades, NASA has conducted several experiments in integrated flight-propulsion control. Benefits have included improved maneuverability; increased thrust, range, and survivability; reduced fuel consumption; and reduced maintenance. This paper presents the basic concepts for control integration, examples of implementation, and benefits. The F-111E experiment integrated the engine and inlet control systems. The YF-12C incorporated an integral control system involving the inlet, autopilot, autothrottle, airdata, navigation, and stability augmentation systems. The F-15 research involved integration of the engine, flight, and inlet control systems. Further extension of the integration included real-time, onboard optimization of engine, inlet, and flight control variables; a self-repairing flight control system; and an engines-only control concept for emergency control. The F-18A aircraft incorporated thrust vectoring integrated with the flight control system to provide enhanced maneuvering at high angles of attack. The flight research programs and the resulting benefits of each program are described.

Interpretation of the Seattle uplift, Washington, as a passive-roof duplex

USGS Publications Warehouse

Brocher, T.M.; Blakely, R.J.; Wells, R.E.

2004-01-01

We interpret seismic lines and a wide variety of other geological and geophysical data to suggest that the Seattle uplift is a passive-roof duplex. A passive-roof duplex is bounded top and bottom by thrust faults with opposite senses of vergence that form a triangle zone at the leading edge of the advancing thrust sheet. In passive-roof duplexes the roof thrust slips only when the floor thrust ruptures. The Seattle fault is a south-dipping reverse fault forming the leading edge of the Seattle uplift, a 40-km-wide fold-and-thrust belt. The recently discovered, north-dipping Tacoma reverse fault is interpreted as a back thrust on the trailing edge of the belt, making the belt doubly vergent. Floor thrusts in the Seattle and Tacoma fault zones, imaged as discontinuous reflections, are interpreted as blind faults that flatten updip into bedding plane thrusts. Shallow monoclines in both the Seattle and Tacoma basins are interpreted to overlie the leading edges of thrust-bounded wedge tips advancing into the basins. Across the Seattle uplift, seismic lines image several shallow, short-wavelength folds exhibiting Quaternary or late Quaternary growth. From reflector truncation, several north-dipping thrust faults (splay thrusts) are inferred to core these shallow folds and to splay upward from a shallow roof thrust. Some of these shallow splay thrusts ruptured to the surface in the late Holocene. Ages from offset soils in trenches across the fault scarps and from abruptly raised shorelines indicate that the splay, roof, and floor thrusts of the Seattle and Tacoma faults ruptured about 1100 years ago.

Kinematic development of the Tibetan Plateau's northern margin: A traverse across the Qilian Shan-Nan Shan thrust belt

NASA Astrophysics Data System (ADS)

Zuza, A. V.; Levy, D. A.; Wang, Z.; Xiong, X.; Chen, X.

2017-12-01

The active Cenozoic Qilian Shan-Nan Shan thrust belt defines the northern margin of the Tibetan Plateau. The kinematic development of this thrust belt has implications models of plateau growth and Himalayan-Tibetan orogen strain accommodation. We present new field observations and analytical data from a traverse across the 350-km-wide doubly vergent Qilian Shan, which is bound by the south-dipping North Qilian thrust system in the north and the north-dipping range-bounding Qinghai Nanshan-Dulan Shan thrust system in the south. These faults, and several other major thrusts within the thrust-belt interior, disrupt relatively thick Oligocene-Miocene basin deposits. Of note, many of the thrust faults across the width of the Qilian Shan have Quaternary fault scarps, indicating that active deformation is distributed and not only concentrated along the northern frontal faults. By integrating our detailed structural traverse with new geophysical observations and thermochronology data across the northern plateau margin, we construct a kinematic model for the development of the Tibetan Plateau's northern margin. Deformation initiated in the Eocene-Oligocene along the north-dipping Qinghai Nanshan-Dulan Shan and south-dipping Tuolai Nan Shan thrusts, the latter of which then defined the northern boundary of the Tibetan Plateau. This early deformation was focused along preexisting early Paleozoic structures. A 200-km-wide basin formed between these ranges, and from the Miocene to present, new thrust- and strike-slip-fault-bounded ranges developed, including the north-directed North Qilian and the south-directed Tuolai Nan thrusts. Thus, our observations do not support northward propagating thrust-belt expansion. Instead, we envision that the initial thrust-belt development generated a wide Oligocene-Miocene north-plateau basin that was subsequently disintegrated by later Miocene to present thrusting and strike-slip faulting. Ultimately, the Qilian Shan-Nan Shan thrust belt differs from a typical orogenic thrust wedge, and active deformation is distributed across the range.

Pliocene episodic exhumation and the significance of the Munsiari thrust in the northwestern Himalaya

NASA Astrophysics Data System (ADS)

Stübner, Konstanze; Grujic, Djordje; Dunkl, István; Thiede, Rasmus; Eugster, Patricia

2018-01-01

The Himalayan thrust belt comprises three in-sequence foreland-propagating orogen-scale faults, the Main Central thrust, the Main Boundary thrust, and the Main Frontal thrust. Recently, the Munsiari-Ramgarh-Shumar thrust system has been recognized as an additional, potentially orogen-scale shear zone in the proximal footwall of the Main Central thrust. The timing of the Munsiari, Ramgarh, and Shumar thrusts and their role in Himalayan tectonics are disputed. We present 31 new zircon (U-Th)/He ages from a profile across the central Himachal Himalaya in the Beas River area. Within a ∼40 km wide belt northeast of the Kullu-Larji-Rampur window, ages ranging from 2.4 ± 0.4 Ma to 5.4 ± 0.9 Ma constrain a distinct episode of rapid Pliocene to Present exhumation; north and south of this belt, zircon (U-Th)/He ages are older (7.0 ± 0.7 Ma to 42.2 ± 2.1 Ma). We attribute the Pliocene rapid exhumation episode to basal accretion to the Himalayan thrust belt and duplex formation in the Lesser Himalayan sequence including initiation of the Munsiari thrust. Pecube thermokinematic modelling suggests exhumation rates of ∼2-3 mm/yr from 4-7 to 0 Ma above the duplex contrasting with lower (<0.3 mm/yr) middle-late Miocene exhumation rates. The Munsiari thrust terminates laterally in central Himachal Pradesh. In the NW Indian Himalaya, the Main Central thrust zone comprises the sheared basal sections of the Greater Himalayan sequence and the mylonitic 'Bajaura nappe' of Lesser Himalayan affinity. We correlate the Bajaura unit with the Ramgarh thrust sheet in Nepal based on similar lithologies and the middle Miocene age of deformation. The Munsiari thrust in the central Himachal Himalaya is several Myr younger than deformation in the Bajaura and Ramgarh thrust sheets. Our results illustrate the complex and segmented nature of the Munsiari-Ramgarh-Shumar thrust system.

Investigation of Pneumatic Inlet and Diffuser Blowing on a Ducted Fan Propulsor in Static Thrust Operation

NASA Technical Reports Server (NTRS)

Kondor, Shayne; Englar, Robert J.; Lee, Warren J.

2003-01-01

Tilting ducted fans present a solution for the lifting and forward flight propulsion requirements of VTOL aircraft. However, the geometry of the duct enshrouding the propeller has great a effect on the efficiency of the fan in various flight modes. Shroud geometry controls the velocity and pressure at the face of the fan, while maintaining a finite loading out at the tips of the fan blades. A duct tailored for most efficient generation of static lifting thrust will generally suffer from performance deficiencies in forward flight. The converse is true as well, leaving the designer with a difficult trade affecting the overall performance and sizing of the aircraft. Ideally, the shroud of a vertical lifting fan features a generous bell mouth inlet promoting acceleration of flow into the face of the fan, and terminating in a converging nozzle at the exit. Flow entering the inlet is accelerated into the fan by the circulation about the shroud, resulting in an overall increase in thrust compared to an open propeller operating under the same conditions . The accelerating shroud design is often employed in lifting ducted fans to benefit from the thrust augmentation; however, such shroud designs produce significant drag penalties in axial flight, thus are unsuitable for efficient forward flight applications. Decelerating, or diffusing, duct designs are employed for higher speed forward flight configurations. The lower circulation on the shroud tends to decelerate the flow into the face of the fan, which is detrimental to static thrust development; however, net thrust is developed on the shroud while the benefits of finite blade loading are retained. With judicious shroud design for intended flight speeds, a net increase in efficiency can be obtained over an open propeller. In this experiment, conducted under contract to NASA LaRC (contract NAG-1-02093) circulation control is being applied to a mildly diffusing shroud design, intended for improved forward flight performance, to generate circulation in the sense of an accelerating duct design. The intent is to improve static thrust performance of a ducted fan tailored for high speed axial flight, while at the same time significantly reduce the pressure signature on the ground plane. Circulation control on the fan shroud is achieved by the Coanda effect.

Validating An Analytic Completeness Model for Kepler Target Stars Based on Flux-level Transit Injection Experiments

NASA Astrophysics Data System (ADS)

Catanzarite, Joseph; Burke, Christopher J.; Li, Jie; Seader, Shawn; Haas, Michael R.; Batalha, Natalie; Henze, Christopher; Christiansen, Jessie; Kepler Project, NASA Advanced Supercomputing Division

2016-06-01

The Kepler Mission is developing an Analytic Completeness Model (ACM) to estimate detection completeness contours as a function of exoplanet radius and period for each target star. Accurate completeness contours are necessary for robust estimation of exoplanet occurrence rates.The main components of the ACM for a target star are: detection efficiency as a function of SNR, the window function (WF) and the one-sigma depth function (OSDF). (Ref. Burke et al. 2015). The WF captures the falloff in transit detection probability at long periods that is determined by the observation window (the duration over which the target star has been observed). The OSDF is the transit depth (in parts per million) that yields SNR of unity for the full transit train. It is a function of period, and accounts for the time-varying properties of the noise and for missing or deweighted data.We are performing flux-level transit injection (FLTI) experiments on selected Kepler target stars with the goal of refining and validating the ACM. “Flux-level” injection machinery inserts exoplanet transit signatures directly into the flux time series, as opposed to “pixel-level” injection, which inserts transit signatures into the individual pixels using the pixel response function. See Jie Li's poster: ID #2493668, "Flux-level transit injection experiments with the NASA Pleiades Supercomputer" for details, including performance statistics.Since FLTI is affordable for only a small subset of the Kepler targets, the ACM is designed to apply to most Kepler target stars. We validate this model using “deep” FLTI experiments, with ~500,000 injection realizations on each of a small number of targets and “shallow” FLTI experiments with ~2000 injection realizations on each of many targets. From the results of these experiments, we identify anomalous targets, model their behavior and refine the ACM accordingly.In this presentation, we discuss progress in validating and refining the ACM, and we compare our detection efficiency curves with those derived from the associated pixel-level transit injection experiments.Kepler was selected as the 10th mission of the Discovery Program. Funding for this mission is provided by NASA, Science Mission Directorate.

Unusual Light in Dark Space Revealed by Los Alamos, NASA

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

Smidt, Joseph

By looking at the dark spaces between visible galaxies and stars the NASA/JPL CIBER sounding rocket experiment has produced data that could redefine what constitutes a galaxy. CIBER, the Cosmic Infrared Background Experiment, is designed to understand the physics going on between visible stars and galaxies. The relatively small, sub-orbital rocket unloads a camera that snaps pictures of the night sky in near-infrared wavelengths, between 1.2 and 1.6 millionth of a meter. Scientists take the data and remove all the known visible stars and galaxies and quantify what is left.

Unusual Light in Dark Space Revealed by Los Alamos, NASA

ScienceCinema

Smidt, Joseph

2018-01-16

By looking at the dark spaces between visible galaxies and stars the NASA/JPL CIBER sounding rocket experiment has produced data that could redefine what constitutes a galaxy. CIBER, the Cosmic Infrared Background Experiment, is designed to understand the physics going on between visible stars and galaxies. The relatively small, sub-orbital rocket unloads a camera that snaps pictures of the night sky in near-infrared wavelengths, between 1.2 and 1.6 millionth of a meter. Scientists take the data and remove all the known visible stars and galaxies and quantify what is left.

Structural analysis using thrust-fault hanging-wall sequence diagrams: Ogden duplex, Wasatch Range, Utah

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

Schirmer, T.W.

1988-05-01

Detailed mapping and cross-section traverses provide the control for structural analysis and geometric modeling of the Ogden duplex, a complex thrust system exposed in the Wasatch Mountains, east of Ogden, Utah. The structures consist of east-dipping folded thrust faults, basement-cored horses, lateral ramps and folds, and tear faults. The sequence of thrusting determined by means of lateral overlap of horses, thrust-splay relationships, and a top-to-bottom piggyback development is Willard thrust, Ogden thrust, Weber thrust, and Taylor thrust. Major decollement zones occur in the Cambrian shales and limestones. The Tintic Quartzite is the marker for determining gross geometries of horses. Thismore » exposed duplex serves as a good model to illustrate the method of constructing a hanging-wall sequence diagram - a series of longitudinal cross sections that move forward in time and space, and show how a thrust system formed as it moved updip over various footwall ramps. A hanging wall sequence diagram also shows the complex lateral variations in a thrust system and helps to locate lateral ramps, lateral folds, tear faults, and other features not shown on dip-oriented cross sections. 8 figures.« less

Predicting Folding Sequences Based on the Maximum Rock Strength and Mechanical Equilibrium

NASA Astrophysics Data System (ADS)

Cubas, N.; Souloumiac, P.; Maillot, B.; Leroy, Y. M.

2007-12-01

The objective is to propose and validate simple procedures, compared to the finite-element method, to select and optimize the dominant mode of folding in fold-and-thrust belts and accretionary wedges, and to determine its stress distribution. Mechanical equilibrium as well as the constraints due to the limited rock strength of the bulk material and of major discontinuities, such as décollements, are accounted for. The first part of the proposed procedure, which is at the core of the external approach of classical limit analysis, consists in estimating the least upper bound on the tectonic force by minimisation of the internal dissipation and part of the external work. The new twist to the method is that the optimization is also done with respect to the geometry of the evolving fold. If several folding events are possible, the dominant mode is the one leading to the least upper bound. The second part of the procedure is based on the Equilibrium Element Method, which is an application of the internal approach of limit analysis. The optimum stress field, obtained by spatial discretisation of the fold, provides the best lower bound on the tectonic force. The difference between the two bounds defines an error estimate of the exact unknown tectonic force. To show the merits of the proposed procedure, its first part is applied to predict the life span of a thrust within an accretionary prism, from its onset, its development with a relief build up and its arrest because of the onset of a more favorable new thrust (Cubas et al., 2007). This life span is sensitive to the friction angles over the ramp and the décollement. It is shown how the normal sequence of thrusting in a supercritical wedge is ended with the first out-of sequence event. The second part of the procedure provides the stress state over each thrust showing that the active back thrust is a narrow fan which dip is sensitive to the friction angle over the ramp and the amount of relief build up (Souloumiac et al., 2007). The stress state is dominated by a concentration at the root of the active ramp and the presence of the back thrust. Analogue experiments with sand demonstrate the ability of the first part of the proposed procedure to predict the position and the lifetime of thrusts, the topographic evolution, as well as the value of the compressive force. The simplicity and lightness of the procedure allows to determine probability distributions of the friction angles of the décollement, the ramps, and the pristine material using an inverse problem formalism. Applied to a section at the front of Nanka'i's wedge, Southeast Japon, the two parts of the method confirm the relative weakness of the basal décollement. From the first part, we conclude that the active thrust is necessarily weaker than the incipient thrust and that the frontal section is likely inhomogeneous. The second part shows that, close to criticality, for minutes changes in the décollement friction angle, the stress concentrations, marking the onset of thrusting, can be positioned at very different locations, the details of which depend on relief irregularities.

Nuclear structure studies with INGA coupled to a fast DDAQ

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

Palit, R.

Studies of different types of nuclear excitation and isomers remain the main thrust area of the last experimental campaign using INGA at TIFR-BARC Pelletron Linac Facility at Mumbai. A digital data acquisition system has been coupled with the INGA which has improved the data throughput and better gain stability. About forty experiments that have been proposed in this experimental campaign. Selected results from these experiments will be discussed.

Nuclear structure studies with INGA coupled to a fast DDAQ

NASA Astrophysics Data System (ADS)

Palit, R.

2014-08-01

Studies of different types of nuclear excitation and isomers remain the main thrust area of the last experimental campaign using INGA at TIFR-BARC Pelletron Linac Facility at Mumbai. A digital data acquisition system has been coupled with the INGA which has improved the data throughput and better gain stability. About forty experiments that have been proposed in this experimental campaign. Selected results from these experiments will be discussed.

Combustion Fundamentals Research

NASA Technical Reports Server (NTRS)

1983-01-01

Increased emphasis is placed on fundamental and generic research at Lewis Research Center with less systems development efforts. This is especially true in combustion research, where the study of combustion fundamentals has grown significantly in order to better address the perceived long term technical needs of the aerospace industry. The main thrusts for this combustion fundamentals program area are as follows: analytical models of combustion processes, model verification experiments, fundamental combustion experiments, and advanced numeric techniques.

Novel approach to improve the attitude update rate of a star tracker.

PubMed

Zhang, Shuo; Xing, Fei; Sun, Ting; You, Zheng; Wei, Minsong

2018-03-05

The star tracker is widely used in attitude control systems of spacecraft for attitude measurement. The attitude update rate of a star tracker is important to guarantee the attitude control performance. In this paper, we propose a novel approach to improve the attitude update rate of a star tracker. The electronic Rolling Shutter (RS) imaging mode of the complementary metal-oxide semiconductor (CMOS) image sensor in the star tracker is applied to acquire star images in which the star spots are exposed with row-to-row time offsets, thereby reflecting the rotation of star tracker at different times. The attitude estimation method with a single star spot is developed to realize the multiple attitude updates by a star image, so as to reach a high update rate. The simulation and experiment are performed to verify the proposed approaches. The test results demonstrate that the proposed approach is effective and the attitude update rate of a star tracker is increased significantly.

Massive stars, disks, and clustered star formation

NASA Astrophysics Data System (ADS)

Moeckel, Nickolas Barry

The formation of an isolated massive star is inherently more complex than the relatively well-understood collapse of an isolated, low-mass star. The dense, clustered environment where massive stars are predominantly found further complicates the picture, and suggests that interactions with other stars may play an important role in the early life of these objects. In this thesis we present the results of numerical hydrodynamic experiments investigating interactions between a massive protostar and its lower-mass cluster siblings. We explore the impact of these interactions on the orientation of disks and outflows, which are potentially observable indications of encounters during the formation of a star. We show that these encounters efficiently form eccentric binary systems, and in clusters similar to Orion they occur frequently enough to contribute to the high multiplicity of massive stars. We suggest that the massive protostar in Cepheus A is currently undergoing a series of interactions, and present simulations tailored to that system. We also apply the numerical techniques used in the massive star investigations to a much lower-mass regime, the formation of planetary systems around Solar- mass stars. We perform a small number of illustrative planet-planet scattering experiments, which have been used to explain the eccentricity distribution of extrasolar planets. We add the complication of a remnant gas disk, and show that this feature has the potential to stabilize the system against strong encounters between planets. We present preliminary simulations of Bondi-Hoyle accretion onto a protoplanetary disk, and consider the impact of the flow on the disk properties as well as the impact of the disk on the accretion flow.

Upper-Stage Flight Experiment

NASA Technical Reports Server (NTRS)

Anderson, W. E.; Boxwell, R.; Crockett, D. V.; Ross, R.; Lewis, T.; McNeal, C.; Verdarame, K.

1999-01-01

For propulsion applications that require that the propellants are storable for long periods, have a high density impulse, and are environmentally clean and non-toxic, the best choice is a combination of high-concentration hydrogen peroxide (High Test Peroxide, or HTP) and a liquid hydrocarbon (LHC) fuel. The HTP/LHC combination is suitable for low-cost launch vehicles, space taxi and space maneuvering vehicles, and kick stages. Orbital Sciences Corporation is under contract with the NASA Marshall Space Flight Center in cooperation with the Air Force Research Lab to design, develop and demonstrate a new low-cost liquid upper stage based on HTP and JP-8. The Upper Stage Flight Experiment (USFE) focuses on key technologies necessary to demonstrate the operation of an inherently simple propulsion system with an innovative, state-of-the-art structure. Two key low-cost vehicle elements will be demonstrated - a 10,000 lbf thrust engine and an integrated composite tank structure. The suborbital flight test of the USFE is scheduled for 2001. Preceding the flight tests are two major series of ground tests at NASA Stennis Space Center and a subscale tank development program to identify compatible composite materials and to verify their compatibility over long periods of time. The ground tests include a thrust chamber development test series and an integrated stage test. This paper summarizes the results from the first phase of the thrust chamber development tests and the results to date from the tank material compatibility tests. Engine and tank configurations that meet the goals of the program are described.

Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

Curtis, Leslie; Johnson, Les; Brown, Norman S. (Technical Monitor)

2002-01-01

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta 11 Expendable Launch Vehicle second stage. ProSEDS, which is planned on an Air Force GPS Satellite replacement mission in June 2002, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5 km bare wire plus 10 km non-conducting Dyneema) from a Delta 11 second stage to achieve approx. 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDS instrumentation includes Langmuir probes and Differential Ion Flux Probes, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations. The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the removal of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.

Propulsive Small Expendable Deployer System (ProSEDS)

NASA Technical Reports Server (NTRS)

Ballance, Judy; Johnson, Les; Rogacki, John R. (Technical Monitor)

2000-01-01

The Propulsive Small Expendable Deployer System (ProSEDS) space experiment will demonstrate the use of an electrodynamic tether propulsion system to generate thrust in space by decreasing the orbital altitude of a Delta II Expendable Launch Vehicle (ELV) second stage. ProSEDS, which is planned to fly in 2001, will use the flight proven Small Expendable Deployer System (SEDS) to deploy a tether (5km bare wire plus 10 km spectra or dyneema) from a Delta II second stage to achieve approximately 0.4N drag thrust. ProSEDS will utilize the tether-generated current to provide limited spacecraft power. The ProSEDs instrumentation includes a Langmuir probe and Differential Ion Flux Probe, which will determine the characteristics of the ambient ionospheric plasma. Two Global Positioning System (GPS) receivers will be used (one on the Delta and one on the endmass) to help determine tether dynamics and to limit transmitter operations to occasions when the spacecraft is over selected ground stations, The flight experiment is a precursor to the more ambitious electrodynamic tether upper stage demonstration mission, which will be capable of orbit raising, lowering and inclination changes-all using electrodynamic thrust. An immediate application of ProSEDS technology is for the deorbit of spent satellites for orbital debris mitigation. In addition to the use of this technology to provide orbit transfer and debris mitigation it may also be an attractive option for future missions to Jupiter and any other planetary body with a magnetosphere.

Evidence for synchronous thin-skinned and basement deformation in the Cordilleran fold-thrust belt: the Tendoy Mountains, southwestern Montana

NASA Astrophysics Data System (ADS)

McDowell, Robin John

1997-01-01

The Tendoy Mountains contain the easternmost thin-skinned thrust sheets in the Cordilleran fold-thrust belt of southwestern Montana, and are in the zone of tectonic overlap between the Rocky Mountain foreland and the Cordilleran fold-thrust belt. The three frontal thrust sheets of the Tendoy Mountains are from north to south, the Armstead, McKenzie, and Tendoy sheets. Near the southeastern terminus of the Tendoy thrust sheet is a lateral ramp in which the Tendoy thrust climbs along strike from the Upper Mississippian Lombard Limestone to lower Cretaceous rocks. This ramp coincides with the southeastern side of the Paleozoic Snowcrest trough and projection of the range-flanking basement thrust of the Blacktail-Snowcrest uplift, suggesting either basement or stratigraphic control on location of the lateral ramp. Axes of major folds on the southern part of the Tendoy thrust sheet are parallel to the direction of thrust transport and to the trend of the Snowcrest Range. They are a result of: (1) Pre-thrust folding above basement faults; (2) Passive transportation of the folds from a down-plunge position; (3) Minor reactivation of basement faults; and (4) Emplacement of blind, sub-Tendoy, thin-skinned thrust faults. The Tendoy sheet also contains a major out-of-sequence thrust fault that formed in thick Upper Mississippian shales and created large, overturned, foreland-verging folds in Upper Mississippian to Triassic rocks. The out-of-sequence fault can be identified where stratigraphic section is omitted, and by a stratigraphic separation diagram that shows it cutting down section in the direction of transport. The prominent lateral ramp at the southern terminus of the Tendoy thrust sheet is a result of fault propagation through strata folded over the edge of the Blacktail-Snowcrest uplift.

Complex thrusting at the toe of the Nankai accretionary prism, NanTroSEIZE Kumano transect

NASA Astrophysics Data System (ADS)

Moore, G. F.; Park, J.; Kodaira, S.; Kaneda, Y.

2009-12-01

Seismic reflection data collected over the past 10 years by the Institute for Research on Earth Evolution (IFREE) of Japan Agency for Marine Earth Science and Technology (JAMSTEC) image a zone of complex thrusting at the toe of the Nankai accretionary prism south of Kii Peninsula, Honshu, Japan. The frontal part of the Nankai prism west of Shionomisaki Canyon (SC) at ~136° E, including the Muroto and Ashizuri Transects off Shikoku, is generally formed of imbricate thrusts with spacing of ~ 1-3 km that dip ~25-35° landward and sole into a prominent décollement. Out-of-sequence thrusts (OOSTs) are usually restricted to the landward margin of this imbricate thrust zone. East of SC, in the Kumano Transect area, the imbricate thrust zone is bounded on its seaward edge by a frontal thrust block that is ~5-6 km wide and consists of several OOSTs. The frontal thrust dips ~5-10° under this ~2-4 km thick block, emplacing this thrust sheet over the trench floor. The number and character of thrusts within the frontal thrust block vary laterally along strike. The 2006 Kumano 3D seismic data set images details of one segment of this complex frontal thrust block. Out-of-sequence faulting has led to underplating of several smaller thrust slices and movement along oblique ramps has led to a complex pattern of faulting that cannot be recognized in even closely-spaced 2D seismic lines. The frontal thrust block is further modified by subduction of seamounts and ridges that have caused large slumps of material from the block.

Theoretical Chemistry Comes Alive: Full Partner with Experiment.

ERIC Educational Resources Information Center

Goddard, William A., III

1985-01-01

The expected thrust for theoretical chemistry in the next decade will be to combine knowledge of fundamental chemical steps/interactions with advances in chemical dynamics, irreversible statistical mechanics, and computer technology to produce simulations of chemical systems with reaction site competition. A sample simulation (using the enzyme…

Luminosity Variations in Post-AGB Stars

NASA Astrophysics Data System (ADS)

Mesler, Robert; Henson, G.

2007-12-01

Although much is known about AGB stars and planetary nebulae, relatively little is known about the phase of a star's life in which it transitions between those two states. We have measured the variations in luminosity of a sample of known Post-AGB stars (as well as several candidates) relative to nearby, non-variable stars in order to compare them with theoretical models. The typical behavior of the observed variations is described and an attempt is made to discern whether any periodicity might be present. Luminosity variations were found to be on the order of a few hundredths to a few tenths of a magnitude for the stars that were surveyed, with occasional fluctuations of up to a magnitude. This agrees with current models of Post-AGB stars. Each star fell into one of three categories, which were termed groups 1, 2, and 3. Group 1 stars showed long term, non-periodic luminosity variations on the scale of weeks or longer and were most likely to display some sort of short term, coherent luminosity oscillation (each of which lasted for only a few cycles). Group 2 stars showed erratic, short-term magnitude variations occurring on scales of several days. Group 3 stars showed little or no variation in magnitude. Of the 27 Post-AGB stars that were sampled, five fell into group 1, fifteen fell into group 2, and seven fell into group 3. The luminosity variations tended to be color-independent, and occurred on timescales ranging nearly continuously from a few days to more than a year. No clear periodic behavior was found in any star in our sample. This project was funded by a partnership between the National Science Foundation (NSF AST-0552798), Research Experiences for Undergraduates (REU), and the Department of Defense (DoD) ASSURE (Awards to Stimulate and Support Undergraduate Research Experiences) programs.

Fluid lubricated bearing assembly

DOEpatents

Boorse, Henry A.; Boeker, Gilbert F.; Menke, John R.

1976-01-01

1. A support for a loaded rotatable shaft comprising in combination on a housing having a fluid-tight cavity encasing an end portion of said shaft, a thrust bearing near the open end of said cavity for supporting the axial thrust of said shaft, said thrust bearing comprising a thrust plate mounted in said housing and a thrust collar mounted on said shaft, said thrust plate having a central opening the peripheral portion of which is hermetically sealed to said housing at the open end of said cavity, and means for supplying a fluid lubricant to said thrust bearing, said thrust bearing having a lubricant-conducting path connecting said lubricant supplying means with the space between said thrust plate and collar intermediate the peripheries thereof, the surfaces of said plate and collar being constructed and arranged to inhibit radial flow of lubricant and, on rotation of said thrust collar, to draw lubricant through said path between the bearing surfaces and to increase the pressure therebetween and in said cavity and thereby exert a supporting force on said end portion of said shaft.

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

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.

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.

Microstructures and strain variation: Evidence of multiple splays in the North Almora Thrust Zone, Kumaun Lesser Himalaya, Uttarakhand, India

NASA Astrophysics Data System (ADS)

Joshi, Gaurav; Agarwal, Amar; Agarwal, K. K.; Srivastava, Samriddhi; Alva Valdivia, L. M.

2017-01-01

The North Almora Thrust zone (NATZ) marks the boundary of the Almora Crystalline Complex (ACC) against the Lesser Himalayan Sedimentary sequence (LHS) in the north. Its southern counterpart, the South Almora Thrust (SAT), is a sharply marked contact between the ACC and the LHS in the south. Published studies argue various contradictory emplacement modes of the North Almora Thrust. Recent studies have implied splays of smaller back thrusts in the NATZ. The present study investigates meso- and microstructures, and strain distribution in the NATZ and compares it with strain distribution across the SAT. In the NATZ, field evidence reveals repeated sequence of 10-500 m thick slices of proto- to ultra-mylonite, thrust over the Lesser Himalayan Rautgara quartzite. In accordance with the field evidence, the strain analysis reveals effects of splays of smaller thrust in the NATZ. The study therefore, argues that contrary to popular nomenclature the northern contact of the ACC with the LHS is not a single thrust plane, but a thrust zone marked by numerous thrust splays.

The S-Star Trial Bioinformatics Course: An On-line Learning Success

ERIC Educational Resources Information Center

Lim, Yun Ping; Hoog, Jan-Olov; Gardner, Phyllis; Ranganathan, Shoba; Andersson, Siv; Subbiah, Subramanian; Tan, Tin Wee; Hide, Winston; Weiss, Anthony S.

2003-01-01

The S-Star Trial Bioinformatics on-line course (www.s-star.org) is a global experiment in bioinformatics distance education. Six universities from five continents have participated in this project. One hundred and fifty students participated in the first trial course of which 96 followed through the entire course and 70 fulfilled the overall…

Effect of azimuthal diversion rail on an ATON-type Hall thruster

NASA Astrophysics Data System (ADS)

Xu, Zhang; Liqiu, Wei; Liang, Han; Yongjie, Ding; Daren, Yu

2017-03-01

A newly designed azimuthal diversion rail (ADR) is studied and used to enhance the ionization process in an ATON-type Hall thruster. The diversion rail efficiently reduces the neutral flow axial velocity, and hence, increases the resistance time of atoms in the discharge channel of the Hall thruster. Thrust performances, in terms of thrust, anode efficiency and ion beam divergence, are found to be improved because of the application of the diversion rail, especially at low mass flow rate conditions. Experiment results reveal that the ADR increases the mass utilization under insufficient mass flow rate operating conditions. The design of the ADR broadens the efficient operating range of Hall thrusters and has significant contribution to multi-mode Hall thruster development.

Laser-Driven Mini-Thrusters

NASA Astrophysics Data System (ADS)

Sterling, Enrique; Lin, Jun; Sinko, John; Kodgis, Lisa; Porter, Simon; Pakhomov, Andrew V.; Larson, C. William; Mead, Franklin B.

2006-05-01

Laser-driven mini-thrusters were studied using Delrin® and PVC (Delrin® is a registered trademark of DuPont) as propellants. TEA CO2 laser (λ = 10.6 μm) was used as a driving laser. Coupling coefficients were deduced from two independent techniques: force-time curves measured with a piezoelectric sensor and ballistic pendulum. Time-resolved ICCD images of the expanding plasma and combustion products were analyzed in order to determine the main process that generates the thrust. The measurements were also performed in a nitrogen atmosphere in order to test the combustion effects on thrust. A pinhole transmission experiment was performed for the study of the cut-off time when the ablation/air breakdown plasma becomes opaque to the incoming laser pulse.

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.

"Star Light, Star Bright..."

ERIC Educational Resources Information Center

Moore, Gil; Doop, Skip; Millson, David

1998-01-01

Describes Student-Tracked Atmospheric Research Satellite for Heuristic International Networking Experiment (STARSHINE), which enables students to explore optical astronomy, orbital dynamics, space and atmospheric physics, mathematics and international cooperation by tracking a satellite. (Author)

Action starring narratives and events: Structure and inference in visual narrative comprehension.

PubMed

Cohn, Neil; Wittenberg, Eva

Studies of discourse have long placed focus on the inference generated by information that is not overtly expressed, and theories of visual narrative comprehension similarly focused on the inference generated between juxtaposed panels. Within the visual language of comics, star-shaped "flashes" commonly signify impacts, but can be enlarged to the size of a whole panel that can omit all other representational information. These "action star" panels depict a narrative culmination (a "Peak"), but have content which readers must infer, thereby posing a challenge to theories of inference generation in visual narratives that focus only on the semantic changes between juxtaposed images. This paper shows that action stars demand more inference than depicted events, and that they are more coherent in narrative sequences than scrambled sequences (Experiment 1). In addition, action stars play a felicitous narrative role in the sequence (Experiment 2). Together, these results suggest that visual narratives use conventionalized depictions that demand the generation of inferences while retaining narrative coherence of a visual sequence.

The Optical Gravitational Lensing Experiment Catalog of stellar proper motions in the OGLE-II Galactic bulge fields

NASA Astrophysics Data System (ADS)

Sumi, T.; Wu, X.; Udalski, A.; Szymański, M.; Kubiak, M.; Pietrzyński, G.; Soszyński, I.; Woźniak, P.; Zebruń, K.; Szewczyk, O.; Wyrzykowski, L.

2003-12-01

We present proper motion (μ ) catalogue of 5,078,188 stars in 49 Optical Gravitational Lensing Experiment II (OGLE-II) Galactic bulge fields, with the total area close to 11 square degrees. The proper motion measurements are based on 138 - 555 I-band images taken during four observing seasons: 1997-2000. The catalogue stars are in the magnitude range 11 < I < 18 mag. In particular, the catalogue includes Red Clump Giants (RCGs) and Red Giants in the Galactic Bulge, and main sequence stars in the Galactic disc. The proper motions up to μ = 500 mas yr -1 were measured with the mean accuracy of 0.8 ˜ 3.5 mas yr-1, depending on the brightness of a star. This catalogue may be useful for studying the kinematic of stars in the Galactic Bulge and the Galactic disk with Extinction maps in these fields which are construncted by using two-band photometry of RCGs.

Attitude Control for an Aero-Vehicle Using Vector Thrusting and Variable Speed Control Moment Gyros

NASA Technical Reports Server (NTRS)

Shin, Jong-Yeob; Lim, K. B.; Moerder, D. D.

2005-01-01

Stabilization of passively unstable thrust-levitated vehicles can require significant control inputs. Although thrust vectoring is a straightforward choice for realizing these inputs, this may lead to difficulties discussed in the paper. This paper examines supplementing thrust vectoring with Variable-Speed Control Moment Gyroscopes (VSCMGs). The paper describes how to allocate VSCMGs and the vectored thrust mechanism for attitude stabilization in frequency domain and also shows trade-off between vectored thrust and VSCMGs. Using an H2 control synthesis methodology in LMI optimization, a feedback control law is designed for a thrust-levitated research vehicle and is simulated with the full nonlinear model. It is demonstrated that VSCMGs can reduce the use of vectored thrust variation for stabilizing the hovering platform in the presence of strong wind gusts.

Evaluation of an Outer Loop Retrofit Architecture for Intelligent Turbofan Engine Thrust Control

NASA Technical Reports Server (NTRS)

Litt, Jonathan S.; Sowers, T. Shane

2006-01-01

The thrust control capability of a retrofit architecture for intelligent turbofan engine control and diagnostics is evaluated. The focus of the study is on the portion of the hierarchical architecture that performs thrust estimation and outer loop thrust control. The inner loop controls fan speed so the outer loop automatically adjusts the engine's fan speed command to maintain thrust at the desired level, based on pilot input, even as the engine deteriorates with use. The thrust estimation accuracy is assessed under nominal and deteriorated conditions at multiple operating points, and the closed loop thrust control performance is studied, all in a complex real-time nonlinear turbofan engine simulation test bed. The estimation capability, thrust response, and robustness to uncertainty in the form of engine degradation are evaluated.

Reverse thrust performance of the QCSEE variable pitch turbofan engine

NASA Technical Reports Server (NTRS)

Samanich, N. E.; Reemsnyder, D. C.; Blodmer, H. E.

1980-01-01

Results of steady state reverse and forward to reverse thrust transient performance tests are presented. The original quiet, clean, short haul, experimental engine four segment variable fan nozzle was retested in reverse and compared with a continuous, 30 deg half angle conical exlet. Data indicated that the significantly more stable, higher pressure recovery flow with the fixed 30 deg exlet resulted in lower engine vibrations, lower fan blade stress, and approximately a 20 percent improvement in reverse thrust. Objective reverse thrust of 35 percent of takeoff thrust was reached. Thrust response of less than 1.5 sec was achieved for the approach and the takeoff to reverse thrust transients.

The Optical Gravitational Lensing Experiment. Eclipsing Binary Stars in the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Wyrzykowski, L.; Udalski, A.; Kubiak, M.; Szymanski, M. K.; Zebrun, K.; Soszynski, I.; Wozniak, P. R.; Pietrzynski, G.; Szewczyk, O.

2004-03-01

We present new version of the OGLE-II catalog of eclipsing binary stars detected in the Small Magellanic Cloud, based on Difference Image Analysis catalog of variable stars in the Magellanic Clouds containing data collected from 1997 to 2000. We found 1351 eclipsing binary stars in the central 2.4 square degree area of the SMC. 455 stars are newly discovered objects, not found in the previous release of the catalog. The eclipsing objects were selected with the automatic search algorithm based on the artificial neural network. The full catalog is accessible from the OGLE Internet archive.

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.

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.

Performance characteristics of two multiaxis thrust-vectoring nozzles at Mach numbers up to 1.28

NASA Technical Reports Server (NTRS)

Wing, David J.; Capone, Francis J.

1993-01-01

The thrust-vectoring axisymmetric (VA) nozzle and a spherical convergent flap (SCF) thrust-vectoring nozzle were tested along with a baseline nonvectoring axisymmetric (NVA) nozzle in the Langley 16-Foot Transonic Tunnel at Mach numbers from 0 to 1.28 and nozzle pressure ratios from 1 to 8. Test parameters included geometric yaw vector angle and unvectored divergent flap length. No pitch vectoring was studied. Nozzle drag, thrust minus drag, yaw thrust vector angle, discharge coefficient, and static thrust performance were measured and analyzed, as well as external static pressure distributions. The NVA nozzle and the VA nozzle displayed higher static thrust performance than the SCF nozzle throughout the nozzle pressure ratio (NPR) range tested. The NVA nozzle had higher overall thrust minus drag than the other nozzles throughout the NPR and Mach number ranges tested. The SCF nozzle had the lowest jet-on nozzle drag of the three nozzles throughout the test conditions. The SCF nozzle provided yaw thrust angles that were equal to the geometric angle and constant with NPR. The VA nozzle achieved yaw thrust vector angles that were significantly higher than the geometric angle but not constant with NPR. Nozzle drag generally increased with increases in thrust vectoring for all the nozzles tested.

Effects of thrust amplitude and duration of high velocity low amplitude spinal manipulation on lumbar muscle spindle responses to vertebral position and movement

PubMed Central

Cao, Dong-Yuan; Reed, William R.; Long, Cynthia R.; Kawchuk, Gregory N.; Pickar, Joel G.

2013-01-01

OBJECTIVE Mechanical characteristics of high velocity low amplitude spinal manipulations (HVLA-SM) can be variable. Sustained changes in peripheral neuronal signaling due to altered load transmission to a sensory receptor’s local mechanical environment are often considered a mechanism contributing to the therapeutic effects of spinal manipulation. The purpose of this study was to determine whether an HVLA-SM’s thrust amplitude or duration altered neural responsiveness of lumbar muscle spindles to either vertebral movement or position. METHODS Anesthetized cats (n=112) received L6 HVLA-SMs delivered to the spinous process. Cats were divided into 6 cohorts depending upon the peak thrust force (25%, 55%, 85% body weight) or thrust displacement (1, 2, 3mm) they received. Cats in each cohort received 8 thrust durations (0–250ms). Afferent discharge from 112 spindles was recorded in response to ramp and hold vertebral movement before and after the manipulation. Changes in mean instantaneous frequency (MIF) during the baseline period preceding the ramps (ΔMIFresting), during ramp movements (ΔMIFmovement), and with the vertebra held in the new position (ΔMIFposition) were compared. RESULTS Thrust duration had a small but statistically significant effect on ΔMIFresting at all six thrust amplitudes compared to control (0ms thrust duration). The lowest amplitude thrust displacement (1mm) increased ΔMIFresting at all thrust durations. For all the other thrust displacements and forces, the direction of change in ΔMIFresting was not consistent and the pattern of change was not systematically related to thrust duration. Regardless of thrust force, displacement, or duration, ΔMIFmovement and ΔMIFposition were not significantly different from control. Conclusion Relatively low amplitude thrust displacements applied during an HVLA-SM produced sustained increases in the resting discharge of paraspinal muscle spindles regardless of the duration over which the thrust was applied. However, regardless of the HVLA-SM’s thrust amplitude or duration, the responsiveness of paraspinal muscle spindles to vertebral movement and to a new vertebral position was not affected. PMID:23499141

STARS: a software application for the EBEX autonomous daytime star cameras

NASA Astrophysics Data System (ADS)

Chapman, Daniel; Didier, Joy; Hanany, Shaul; Hillbrand, Seth; Limon, Michele; Miller, Amber; Reichborn-Kjennerud, Britt; Tucker, Greg; Vinokurov, Yury

2014-07-01

The E and B Experiment (EBEX) is a balloon-borne telescope designed to probe polarization signals in the CMB resulting from primordial gravitational waves, gravitational lensing, and Galactic dust emission. EBEX completed an 11 day flight over Antarctica in January 2013 and data analysis is underway. EBEX employs two star cameras to achieve its real-time and post-flight pointing requirements. We wrote a software application called STARS to operate, command, and collect data from each of the star cameras, and to interface them with the main flight computer. We paid special attention to make the software robust against potential in-flight failures. We report on the implementation, testing, and successful in flight performance of STARS.

Fin Ray Stiffness and Fin Morphology Control Ribbon-Fin-Based Propulsion.

PubMed

Liu, Hanlin; Taylor, Bevan; Curet, Oscar M

2017-06-01

Ribbon-fin-based propulsion has rich locomotor capabilities that can enhance the mobility and performance of underwater vehicles navigating in complex environments. Bony fishes using this type of propulsion send one or multiple traveling waves along an elongated fin with the actuation of highly flexible rays that are interconnected by an elastic membrane. In this work, we study how the use of flexible rays and different morphology can affect the performance of ribbon-fin propulsion. We developed a physical model composed of 15 rays that are interconnected with an elastic membrane. We tested four different ray flexural stiffness and four aspect ratios. The robotic model was tested in a low-turbulence flume under two flow conditions ([Formula: see text] wavelength/s). In two experimental sets, we measured fin kinematics, net surge forces, and power consumption. Using these data, we perform a thrust and power analysis of the undulating fin. We present the thrust coefficient, power coefficient, and propulsive efficiency. We find that the thrust generation was linear with the enclosed area swept by the fin, and square of the relative velocity between the incoming flow and traveling wave. The thrust coefficient levels off around 0.5. In addition, for our parameter range, we find that the power consumption scales by the cube of the effective tangential velocity of the rays [Formula: see text] (A is the amplitude of the ray oscillating motion, and [Formula: see text] is the angular velocity). We show that a decay in stiffness decreases both thrust production and power consumption. However, for rays with high flexural stiffness, the difference in thrust compared with rigid rays is minimal. Moreover, our results show that flexible rays can improve the propulsive efficiency compared with a rigid counterpart. Finally, we find that the morphology of ribbon fin affects its propulsive efficiency. For the aspect ratio considered in our experiments, [Formula: see text] was the most efficient compared with [Formula: see text]. Our results suggest that there could be an optimal morphology for a given ribbon fin kinematics. Therefore, both natural swimmers and underwater vehicles using ribbon-fin-based propulsion can take advantage of flexible rays and optimal aspect ratio to improve propulsive performance.

Structural evidence for northeastward movement on the Chocolate Mountains Thrust, southeasternmost California

USGS Publications Warehouse

Dillon, J.T.; Haxel, G.B.; Tosdal, R.M.

1990-01-01

The Late Cretaceous Chocolate Mountains Thrust of southeastern California and southwestern Arizona places a block of Proterozoic and Mesozoic continental crust over the late Mesozoic continental margin oceanic sedimentary and volcanic rocks of the Orocopia Schist. The Chocolate Mountains Thrust is interpreted as a thrust (burial, subduction) fault rather than a low-angle normal fault. An important parameter required to understand the tectonic significance of the Chocolate Mountains and related thrusts is their sense of movement. The only sense of movement consistent with collective asymmetry of the thrust zone folds is top to the northeast. Asymmetric microstructures studied at several localities also indicate top to the northeast movement. Paleomagnetic data suggest that the original sense of thrusting, prior to Neogene vertical axis tectonic rotation related to the San Andreas fault system, was northward. Movement of the upper plate of the chocolate Mountains thrust evidently was continentward. Continentward thrusting suggests a tectonic scenario in which an insular or peninsular microcontinental fragment collided with mainland southern California. -from Authors

Imaging Water in Deformed Quartzites: Examples from Caledonian and Himalayan Shear Zones

NASA Astrophysics Data System (ADS)

Kronenberg, Andreas; Ashley, Kyle; Hasnan, Hasnor; Holyoke, Caleb; Jezek, Lynna; Law, Richard; Thomas, Jay

2016-04-01

Infrared IR measurements of OH absorption bands due to water in deformed quartz grains have been collected from major shear zones of the Caledonian and Himalayan orogens. Mean intragranular water contents were determined from the magnitude of the broad OH absorption at 3400 cm-1 as a function of structural position, averaging over multiple grains, using an IR microscope coupled to a conventional FTIR spectrometer with apertures of 50-100 μm. Images of water content were generated by scanning areas of up to 4 mm2 of individual specimens with a 10 μm synchrotron-generated IR beam and contouring OH absorptions. Water contents vary with structural level relative to the central cores of shear zones and they vary at the grain scale corresponding to deformation and recrystallization microstructures. Gradients in quartz water content expressed over structural distances of 10 to 400 m from the centers of the Moine Thrust (Stack of Glencoul, NW Scotland), the Main Central Thrust (Sutlej valley of NW India), and the South Tibetan Detachment System (Rongbuk valley north of Mount Everest) indicate that these shear zones functioned as fluid conduits. However, the gradients differ substantially: in some cases, enhanced fluid fluxes appear to have increased quartz water contents, while in others, they served to decrease water contents. Water contents of Moine thrust quartzites appear to have been reduced during shear at greenschist facies by processes of regime II BLG/SGR dislocation creep. Intragranular water contents of the protolith 70 m below the central fault core are large (4078 ± 247 ppm, H/106 Si) while mylonites within 5 mm of the Moine hanging wall rocks have water contents of only 1570 (± 229) ppm. Water contents between these extremes vary systematically with structural level and correlate inversely with the extent of dynamic recrystallization (20 to 100%). Quartz intragranular water contents of Himalayan thrust and low-angle detachment zones sheared at upper amphibolite conditions by regime III GBM creep show varying trends with structural level. Water contents increase toward the Lhotse detachment of the Rongbuk valley, reaching 11,350 (± 1095) ppm, whereas they decrease toward the Main Central Thrust exposed in the western part of the Sutlej valley to values as low as 170 (± 25) ppm. Maps of intragranular water content correspond to populations of fluid inclusions, which depend on the history of deformation and dynamic recrystallization. Increases in water content require the introduction of secondary fluid inclusions, generally by brittle microcracking followed by crack healing and processes of inclusion redistribution documented in milky quartz experiments. Decreases in water content result from dynamic recrystallization, as mobile grain boundaries sweep through wet porphyroclasts, leaving behind dry recrystallized grains. Intragranular water contents throughout greenschist mylonites of the Moine thrust are comparable to those of quartz weakened by water in laboratory experiments. However, water contents of upper amphibolite mylonites of the Main Central Thrust are far below those required for water weakening at experimental strain rates and offer challenges to our understanding of quartz rheology.

Region-confined restoration method for motion-blurred star image of the star sensor under dynamic conditions.

PubMed

Ma, Liheng; Bernelli-Zazzera, Franco; Jiang, Guangwen; Wang, Xingshu; Huang, Zongsheng; Qin, Shiqiao

2016-06-10

Under dynamic conditions, the centroiding accuracy of the motion-blurred star image decreases and the number of identified stars reduces, which leads to the degradation of the attitude accuracy of the star sensor. To improve the attitude accuracy, a region-confined restoration method, which concentrates on the noise removal and signal to noise ratio (SNR) improvement of the motion-blurred star images, is proposed for the star sensor under dynamic conditions. A multi-seed-region growing technique with the kinematic recursive model for star image motion is given to find the star image regions and to remove the noise. Subsequently, a restoration strategy is employed in the extracted regions, taking the time consumption and SNR improvement into consideration simultaneously. Simulation results indicate that the region-confined restoration method is effective in removing noise and improving the centroiding accuracy. The identification rate and the average number of identified stars in the experiments verify the advantages of the region-confined restoration method.

Hot H2O Emission and Evidence for Turbulence in the Disk of a Young Star

DTIC Science & Technology

2004-03-01

matter — infrared: stars — planetary systems: protoplanetary disks — stars: formation — stars: pre–main-sequence 1. INTRODUCTION The presence of hot...in disk gaps . Molecules other than CO are expected to exist at the temperatures and densities in the inner few AU of disks . Water should be very... protoplanetary disks . In addition, non-Gaussian line profiles might be ex- pected, given that a characteristic of turbulence seen in both laboratory experiments

Dark SU (N ) glueball stars on fluid branes

NASA Astrophysics Data System (ADS)

da Rocha, Roldão

2017-06-01

The glueball dark matter, in the pure SU (N ) Yang-Mills theory, engenders dark SU (N ) stars that comprise self-gravitating compact configurations of scalar glueball fields. Corrections to the highest frequency of gravitational wave radiation emitted by dark SU (N ) star mergers on a fluid brane with variable tension, implemented by the minimal geometric deformation, are derived, and their consequences are analyzed. Hence, dark SU (N ) star mergers on a fluid braneworld are shown to be better detectable by the LIGO and the eLISA experiments.

Neutron stars at the dark matter direct detection frontier

NASA Astrophysics Data System (ADS)

Raj, Nirmal; Tanedo, Philip; Yu, Hai-Bo

2018-02-01

Neutron stars capture dark matter efficiently. The kinetic energy transferred during capture heats old neutron stars in the local galactic halo to temperatures detectable by upcoming infrared telescopes. We derive the sensitivity of this probe in the framework of effective operators. For dark matter heavier than a GeV, we find that neutron star heating can set limits on the effective operator cutoff that are orders of magnitude stronger than possible from terrestrial direct detection experiments in the case of spin-dependent and velocity-suppressed scattering.

A simplified gross thrust computing technique for an afterburning turbofan engine

NASA Technical Reports Server (NTRS)

Hamer, M. J.; Kurtenbach, F. J.

1978-01-01

A simplified gross thrust computing technique extended to the F100-PW-100 afterburning turbofan engine is described. The technique uses measured total and static pressures in the engine tailpipe and ambient static pressure to compute gross thrust. Empirically evaluated calibration factors account for three-dimensional effects, the effects of friction and mass transfer, and the effects of simplifying assumptions for solving the equations. Instrumentation requirements and the sensitivity of computed thrust to transducer errors are presented. NASA altitude facility tests on F100 engines (computed thrust versus measured thrust) are presented, and calibration factors obtained on one engine are shown to be applicable to the second engine by comparing the computed gross thrust. It is concluded that this thrust method is potentially suitable for flight test application and engine maintenance on production engines with a minimum amount of instrumentation.

Frozen Chemistry Effects on Nozzle Performance Simulations

NASA Technical Reports Server (NTRS)

Yoder, Dennis A.; Georgiadis, Nicholas J.; O'Gara, Michael R.

2009-01-01

Simulations of exhaust nozzle flows are typically conducted assuming the gas is calorically perfect, and typically modeled as air. However the gas inside a real nozzle is generally composed of combustion products whose thermodynamic properties may differ. In this study, the effect of gas model assumption on exhaust nozzle simulations is examined. The three methods considered model the nozzle exhaust gas as calorically perfect air, a calorically perfect exhaust gas mixture, and a frozen exhaust gas mixture. In the latter case the individual non-reacting species are tracked and modeled as a gas which is only thermally perfect. Performance parameters such as mass flow rate, gross thrust, and thrust coefficient are compared as are mean flow and turbulence profiles in the jet plume region. Nozzles which operate at low temperatures or have low subsonic exit Mach numbers experience relatively minor temperature variations inside the nozzle, and may be modeled as a calorically perfect gas. In those which operate at the opposite extreme conditions, variations in the thermodynamic properties can lead to different expansion behavior within the nozzle. Modeling these cases as a perfect exhaust gas flow rather than air captures much of the flow features of the frozen chemistry simulations. Use of the exhaust gas reduces the nozzle mass flow rate, but has little effect on the gross thrust. When reporting nozzle thrust coefficient results, however, it is important to use the appropriate gas model assumptions to compute the ideal exit velocity. Otherwise the values obtained may be an overly optimistic estimate of nozzle performance.

Magnetized Target Fusion

NASA Technical Reports Server (NTRS)

Griffin, Steven T.

2002-01-01

Magnetized target fusion (MTF) is under consideration as a means of building a low mass, high specific impulse, and high thrust propulsion system for interplanetary travel. This unique combination is the result of the generation of a high temperature plasma by the nuclear fusion process. This plasma can then be deflected by magnetic fields to provide thrust. Fusion is initiated by a small traction of the energy generated in the magnetic coils due to the plasma's compression of the magnetic field. The power gain from a fusion reaction is such that inefficiencies due to thermal neutrons and coil losses can be overcome. Since the fusion reaction products are directly used for propulsion and the power to initiate the reaction is directly obtained from the thrust generation, no massive power supply for energy conversion is required. The result should be a low engine mass, high specific impulse and high thrust system. The key is to successfully initiate fusion as a proof-of-principle for this application. Currently MSFC is implementing MTF proof-of-principle experiments. This involves many technical details and ancillary investigations. Of these, selected pertinent issues include the properties, orientation and timing of the plasma guns and the convergence and interface development of the "pusher" plasma. Computer simulations of the target plasma's behavior under compression and the convergence and mixing of the gun plasma are under investigation. This work is to focus on the gun characterization and development as it relates to plasma initiation and repeatability.

Ignition and Performance Tests of Rocket-Based Combined Cycle Propulsion System

NASA Technical Reports Server (NTRS)

Anderson, William E.

2005-01-01

The ground testing of a Rocket Based Combined Cycle engine implementing the Simultaneous Mixing and Combustion scheme was performed at the direct-connect facility of Purdue University's High Pressure Laboratory. The fuel-rich exhaust of a JP-8/H2O2 thruster was mixed with compressed, metered air in a constant area, axisymmetric duct. The thruster was similar in design and function to that which will be used in the flight test series of Dryden's Ducted-Rocket Experiment. The determination of duct ignition limits was made based on the variation of secondary air flow rates and primary thruster equivalence ratios. Thrust augmentation and improvements in specific impulse were studied along with the pressure and temperature profiles of the duct to study mixing lengths and thermal choking. The occurrence of ignition was favored by lower rocket equivalence ratios. However, among ignition cases, better thrust and specific impulse performance were seen with higher equivalence ratios owing to the increased fuel available for combustion. Thrust and specific impulse improvements by factors of 1.2 to 1.7 were seen. The static pressure and temperature profiles allowed regions of mixing and heat addition to be identified. The mixing lengths were found to be shorter at lower rocket equivalence ratios. Total pressure measurements allowed plume-based calculation of thrust, which agreed with load-cell measured values to within 6.5-8.0%. The corresponding Mach Number profile indicated the flow was not thermally choked for the highest duct static pressure case.

Mini-STAR: A small space mission testing special relativity

NASA Astrophysics Data System (ADS)

Gürlebeck, Norman

mSTAR (mini-STAR) is a proposed collaborative Saudi-USA-German small space mission to perform an advanced Kennedy-Thorndike (KT) type test of Special Relativity using the large and rapid velocity modulation available in low Earth orbit (LEO). An improvement of about a factor of 100 over present ground results is expected with an additional factor of 10 possible using more advanced technology. To date, limits on local Lorentz invariance violations (LLIV) related to boost effects are on the order of δc/c ≤ 10 15. While advances in technology will undoubtedly lead to further gains, it has become clear that space experiments in low Earth orbit offer a way to obtain much better results than ground experiments. The mSTAR LLIV experiment consists of the comparison of a molecular frequency reference, 532 nm Iodine, with a length reference, an optical cavity, in a LEO flight (7 km/s orbital velocity, 90 min period). The corresponding sensitivity to boost-dependent LLIV terms is improved relative to Earth based measurements because of the high velocity modulation and the increased number of the measurements. The mSTAR approach is to develop a small-scale instrument with a high scientific output that also provides instrument and spacecraft technology for subsequent missions, which would use further improved frequency standards.

My eyes, your eyes--the relationship between CMS five-star rating of nursing homes and family rating of experience of care in Maryland.

PubMed

Çalıkoğlu, Şule; Christmyer, Carol S; Kozlowski, Bruce U

2012-01-01

In 2008, the Centers for Medicaid and Medicare Services (CMS) launched the Five-Star Quality Rating System to help consumers compare nursing homes. The quality rating system consists of three domains: nursing home inspection results, staffing, and quality measures (QMs) and an overall rating calculated from the three domains. The Five-Star System has both advocates and detractors. One source of criticism about the rating system is its lack of input from consumer surveys. Although different dimensions of quality have been recognized as important by the experts and studied in the literature, how these dimensions are linked with each other is largely unknown. This article describes an analysis of the relationship between overall experience of care ratings from a family survey and ratings obtained on the CMS Five-Star Quality Rating for Maryland nursing homes. The results indicated a strong positive correlation between family experience of care score and two five-star domains, namely health inspections and nurse staffing, and no relationship with the quality domain. The lack of relationship between the quality domain and the family score may be due to inadequate risk adjustment or that each rating system measures different aspects of quality. © 2011 National Association for Healthcare Quality.

Longitudinal Double-Spin Asymmetry ALL for Inclusive Jet Production in Polarized Proton Collisions at √s = 510 GeV

NASA Astrophysics Data System (ADS)

Quintero, Amilkar; STAR Collaboration

2017-09-01

The STAR experiment at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory is carrying out a spin physics program in high-energy polarized proton collisions at center of mass energies up to 510 GeV, to gain a deeper insight into the spin structure and dynamics of the proton. The polarized gluon distribution function can be constrained in longitudinally polarized proton collisions through jet / di-jet production. Recent global analyses, which include results of the measurement of ALL for inclusive jet production at 200 GeV at mid-rapidity at the STAR experiment, provide evidence of a non-zero gluon polarization in the measured range of partonic momentum fraction of approximately 0.05

CCD centroiding experiment for JASMINE and ILOM

NASA Astrophysics Data System (ADS)

Yano, Taihei; Araki, Hiroshi; Gouda, Naoteru; Kobayashi, Yukiyasu; Tsujimoto, Takuji; Nakajima, Tadashi; Kawano, Nobuyuki; Tazawa, Seiichi; Yamada, Yoshiyuki; Hanada, Hideo; Asari, Kazuyoshi; Tsuruta, Seiitsu

2006-06-01

JASMINE and ILOM are space missions which are in progress at the National Astronomical Observatory of Japan. These two projects need a common astrometric technique to obtain precise positions of star images on solid state detectors to accomplish the objectives. We have carried out measurements of centroid of artificial star images on a CCD to investigate the accuracy of the positions of the stars, using an algorithm for estimating them from photon weighted means of the stars. We find that the accuracy of the star positions reaches 1/300 pixel for one measurement. We also measure positions of stars, using an algorithm for correcting the distorted optical image. Finally, we find that the accuracy of the measurement for the positions of the stars from the strongly distorted image is under 1/150 pixel for one measurement.

An antiproton driver for ICF propulsion

NASA Technical Reports Server (NTRS)

Chiang, Pi-Ren; Lewis, R. A.; Smith, G. A.; Gazze, C.; Higman, K.; Newton, R.; Chiaverini, M.; Dailey, J.; Surratt, M.; Werthman, W. Lance

1993-01-01

Inertial confinement fusion (ICF) utilizing an anitprotoncatalyzed target is discussed as a possible source of propulsion for rapid interplanetary manned space missions. The relevant compression, ignition, and thrust mechanisms are presented. Progress on an experiment presently in progress at the Phillips Laboratory, Kirtland AFB, NM to demonstrate proof-of-principle is reviewed.

Low Thrust Orbital Maneuvers Using Ion Propulsion

NASA Astrophysics Data System (ADS)

Ramesh, Eric

2011-10-01

Low-thrust maneuver options, such as electric propulsion, offer specific challenges within mission-level Modeling, Simulation, and Analysis (MS&A) tools. This project seeks to transition techniques for simulating low-thrust maneuvers from detailed engineering level simulations such as AGI's Satellite ToolKit (STK) Astrogator to mission level simulations such as the System Effectiveness Analysis Simulation (SEAS). Our project goals are as follows: A) Assess different low-thrust options to achieve various orbital changes; B) Compare such approaches to more conventional, high-thrust profiles; C) Compare computational cost and accuracy of various approaches to calculate and simulate low-thrust maneuvers; D) Recommend methods for implementing low-thrust maneuvers in high-level mission simulations; E) prototype recommended solutions.

STS-52 Mission Insignia

NASA Technical Reports Server (NTRS)

1992-01-01

The STS-52 insignia, designed by the mission's crew members, features a large gold star to symbolize the crew's mission on the frontiers of space. A gold star is often used to symbolize the frontier period of the American West. The red star in the shape of the Greek letter lambda represents both the laser measurements taken from the Laser Geodynamic Satellite (LAGEOS II) and the Lambda Point Experiment, which was part of the United States Microgravity Payload (USMP-l). The remote manipulator and maple leaf are emblematic of the Canadian payload specialist who conducted a series of Canadian flight experiments (CANEX-2), including the Space Vision System test.

Space Shuttle Projects

NASA Image and Video Library

1992-10-20

The STS-52 insignia, designed by the mission’s crew members, features a large gold star to symbolize the crew's mission on the frontiers of space. A gold star is often used to symbolize the frontier period of the American West. The red star in the shape of the Greek letter lambda represents both the laser measurements taken from the Laser Geodynamic Satellite (LAGEOS II) and the Lambda Point Experiment, which was part of the United States Microgravity Payload (USMP-l). The remote manipulator and maple leaf are emblematic of the Canadian payload specialist who conducted a series of Canadian flight experiments (CANEX-2), including the Space Vision System test.

Optical-NIR dust extinction towards Galactic O stars

NASA Astrophysics Data System (ADS)

Maíz Apellániz, J.; Barbá, R. H.

2018-05-01

Context. O stars are excellent tracers of the intervening ISM because of their high luminosity, blue intrinsic SED, and relatively featureless spectra. We are currently conducting the Galactic O-Star Spectroscopic Survey (GOSSS), which is generating a large sample of O stars with accurate spectral types within several kpc of the Sun. Aims: We aim to obtain a global picture of the properties of dust extinction in the solar neighborhood based on optical-NIR photometry of O stars with accurate spectral types. Methods: We have processed a carefully selected photometric set with the CHORIZOS code to measure the amount [E(4405 - 5495)] and type [R5495] of extinction towards 562 O-type stellar systems. We have tested three different families of extinction laws and analyzed our results with the help of additional archival data. Results: The Maíz Apellániz et al. (2014, A&A, 564, A63) family of extinction laws provides a better description of Galactic dust that either the Cardelli et al. (1989, ApJ, 345, 245) or Fitzpatrick (1999, PASP, 111, 63) families, so it should be preferentially used when analysing samples similar to the one in this paper. In many cases O stars and late-type stars experience similar amounts of extinction at similar distances but some O stars are located close to the molecular clouds left over from their births and have larger extinctions than the average for nearby late-type populations. In qualitative terms, O stars experience a more diverse extinction than late-type stars, as some are affected by the small-grain-size, low-R5495 effect of molecular clouds and others by the large-grain-size, high-R5495 effect of H II regions. Late-type stars experience a narrower range of grain sizes or R5495, as their extinction is predominantly caused by the average, diffuse ISM. We propose that the reason for the existence of large-grain-size, high-R5495 regions in the ISM in the form of H II regions and hot-gas bubbles is the selective destruction of small dust grains by EUV photons and possibly by thermal sputtering by atoms or ions. Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/613/A9

Is Identification with School the Key Component in the "Black Box" of Education Outcomes? Evidence from a Randomized Experiment

ERIC Educational Resources Information Center

Fletcher, Jason M.

2009-01-01

In this paper, we follow up the important class size reduction randomized experiment in Tennessee in the mid 1980s (Project STAR) to attempt to further understand the long-lasting influences of early education interventions. While STAR led to large test score benefits during the intervention, these benefits quickly faded at its conclusion.…

On the calculation of low-thrust fail-safe trajectories

NASA Technical Reports Server (NTRS)

Sauer, C. G., Jr.

1975-01-01

A guidance algorithm is developed for a low-thrust spacecraft such that target intercept is possible in spite of premature thrust termination along the trajectory. Such a trajectory is called a 'fail-safe' trajectory and the spacecraft thrust is utilized to minimize the relative target-spacecraft approach speed. The fail-safe guidance algorithm is solved using the concept of a critical thrust plane and a non-critical thrust direction. Several examples of fail-safe guidance are presented for a solar-electric propulsion flyby mission to the comet Encke.

Fault-related fluid flow, Beech Mountain thrust sheet, Blue Ridge Province, Tennessee-North Carolina

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

Waggoner, W.K.; Mora, C.I.

1992-01-01

The latest proterozoic Beech Granite is contained within the Beech Mountain thrust sheet (BMTS), part of a middle-late Paleozoic thrust complex located between Mountain City and Grandfather Mountain windows in the western Blue Ridge of TN-NC. At the base of the BMTS, Beech Granite is juxtaposed against lower Paleozoic carbonate and elastics of the Rome Fm. along the Stone Mountain thrust on the southeaster margin of the Mountain City window. At the top of the BMTS, Beech Granite occurs adjacent to Precambrian mafic rocks of the Pumpkin Patch thrust sheet (PPTS). The Beech Granite is foliated throughout the BMTS withmore » mylonitization and localized cataclasis occurring within thrust zones along the upper and lower margins of the BMTS. Although the degree of mylonitization and cataclasis increases towards the thrusts, blocks of relatively undeformed granite also occur within these fault zones. Mylonites and thrusts are recognized as conduits for fluid movement, but the origin of the fluids and magnitude and effects of fluid migration are not well constrained. This study was undertaken to characterize fluid-rock interaction within the Beech Granite and BMTS. Extensive mobility of some elements/compounds within the thrust zones, and the isotopic and mineralogical differences between the thrust zones and interior of the BMTS indicate that fluid flow was focused within the thrust zones. The wide range of elevated temperatures (400--710 C) indicated by qz-fsp fractionations suggest isotopic disequilibrium. Using a more likely temperature range of 300--400 C for Alleghanian deformation, calculated fluid compositions indicate interactions with a mixture of meteoric-hydrothermal and metamorphic water with delta O-18 = 2.6--7.5[per thousand] for the upper thrust zone and 1.3 to 6.2[per thousand] for the lower thrust zone. These ranges are similar to isotopic data reported for other Blue Ridge thrusts and may represent later periods of meteoric water influx.« less

Investigation of Asymmetric Thrust Detection with Demonstration in a Real-Time Simulation Testbed

NASA Technical Reports Server (NTRS)

Chicatelli, Amy; Rinehart, Aidan W.; Sowers, T. Shane; Simon, Donald L.

2015-01-01

The purpose of this effort is to develop, demonstrate, and evaluate three asymmetric thrust detection approaches to aid in the reduction of asymmetric thrust-induced aviation accidents. This paper presents the results from that effort and their evaluation in simulation studies, including those from a real-time flight simulation testbed. Asymmetric thrust is recognized as a contributing factor in several Propulsion System Malfunction plus Inappropriate Crew Response (PSM+ICR) aviation accidents. As an improvement over the state-of-the-art, providing annunciation of asymmetric thrust to alert the crew may hold safety benefits. For this, the reliable detection and confirmation of asymmetric thrust conditions is required. For this work, three asymmetric thrust detection methods are presented along with their results obtained through simulation studies. Representative asymmetric thrust conditions are modeled in simulation based on failure scenarios similar to those reported in aviation incident and accident descriptions. These simulated asymmetric thrust scenarios, combined with actual aircraft operational flight data, are then used to conduct a sensitivity study regarding the detection capabilities of the three methods. Additional evaluation results are presented based on pilot-in-the-loop simulation studies conducted in the NASA Glenn Research Center (GRC) flight simulation testbed. Data obtained from this flight simulation facility are used to further evaluate the effectiveness and accuracy of the asymmetric thrust detection approaches. Generally, the asymmetric thrust conditions are correctly detected and confirmed.

Investigation of Asymmetric Thrust Detection with Demonstration in a Real-Time Simulation Testbed

NASA Technical Reports Server (NTRS)

Chicatelli, Amy K.; Rinehart, Aidan W.; Sowers, T. Shane; Simon, Donald L.

2016-01-01

The purpose of this effort is to develop, demonstrate, and evaluate three asymmetric thrust detection approaches to aid in the reduction of asymmetric thrust-induced aviation accidents. This paper presents the results from that effort and their evaluation in simulation studies, including those from a real-time flight simulation testbed. Asymmetric thrust is recognized as a contributing factor in several Propulsion System Malfunction plus Inappropriate Crew Response (PSM+ICR) aviation accidents. As an improvement over the state-of-the-art, providing annunciation of asymmetric thrust to alert the crew may hold safety benefits. For this, the reliable detection and confirmation of asymmetric thrust conditions is required. For this work, three asymmetric thrust detection methods are presented along with their results obtained through simulation studies. Representative asymmetric thrust conditions are modeled in simulation based on failure scenarios similar to those reported in aviation incident and accident descriptions. These simulated asymmetric thrust scenarios, combined with actual aircraft operational flight data, are then used to conduct a sensitivity study regarding the detection capabilities of the three methods. Additional evaluation results are presented based on pilot-in-the-loop simulation studies conducted in the NASA Glenn Research Center (GRC) flight simulation testbed. Data obtained from this flight simulation facility are used to further evaluate the effectiveness and accuracy of the asymmetric thrust detection approaches. Generally, the asymmetric thrust conditions are correctly detected and confirmed.

Combined high and low-thrust geostationary orbit insertion with radiation constraint

NASA Astrophysics Data System (ADS)

Macdonald, Malcolm; Owens, Steven Robert

2018-01-01

The sequential use of an electric propulsion system is considered in combination with a high-thrust propulsion system for application to the propellant-optimal Geostationary Orbit insertion problem, whilst considering both temporal and radiation flux constraints. Such usage is found to offer a combined propellant mass saving when compared with an equivalent high-thrust only transfer. This propellant mass saving is seen to increase as the allowable transfer duration is increased, and as the thrust from the low-thrust system is increased, assuming constant specific impulse. It was found that the required plane change maneuver is most propellant-efficiently performed by the high-thrust system. The propellant optimal trajectory incurs a significantly increased electron flux when compared to an equivalent high-thrust only transfer. However, the electron flux can be reduced to a similar order of magnitude by increasing the high-thrust propellant consumption, whilst still delivering an improved mass fraction.

Thrust Control Loop Design for Electric-Powered UAV

NASA Astrophysics Data System (ADS)

Byun, Heejae; Park, Sanghyuk

2018-04-01

This paper describes a process of designing a thrust control loop for an electric-powered fixed-wing unmanned aerial vehicle equipped with a propeller and a motor. In particular, the modeling method of the thrust system for thrust control is described in detail and the propeller thrust and torque force are modeled using blade element theory. A relation between current and torque of the motor is obtained using an experimental setup. Another relation between current, voltage and angular velocity is also obtained. The electric motor and the propeller dynamics are combined to model the thrust dynamics. The associated trim and linearization equations are derived. Then, the thrust dynamics are coupled with the flight dynamics to allow a proper design for the thrust loop in the flight control. The proposed method is validated by an application to a testbed UAV through simulations and flight test.

Crystallization of the Pulsating White Dwarf Star, BPM 37093

NASA Astrophysics Data System (ADS)

Salois, Amee; Winget, D.

2010-01-01

BPM 37093 is unique among pulsating white dwarf stars because it is expected to have a highly crystallized interior. By understanding how this star is crystallizing, we gain a better understanding of extreme physics. Theoretical models of the evolution of white dwarf stars suggest that they crystallize from the inside out. The pulsations of the star, which we see as intensity variations, cannot penetrate this crystallized interior. Therefore, as the star crystallizes there is a smaller volume for the propagation of the pulsations and the pulsation periods are changed accordingly. We studied these changes in the periods of the pulsations of the star over ten weeks during the McDonald Observatory Research Experience for Undergraduates Program. By studying the changes in the pulsations periods of the star we can determine the mass fraction of the star that is crystallized. Comparing Fourier transforms of our observed light curves taken in 2004 and 2005 at CTIO with data taken in 1998 and 1999 by Kanaan et al. we hope to see the changes that have occurred in the star as well as determining a better approximation of the star's crystallized mass fraction.

A possible explanation for foreland thrust propagation

NASA Astrophysics Data System (ADS)

Panian, John; Pilant, Walter

1990-06-01

A common feature of thin-skinned fold and thrust belts is the sequential nature of foreland directed thrust systems. As a rule, younger thrusts develop in the footwalls of older thrusts, the whole sequence propagating towards the foreland in the transport direction. As each new younger thrust develops, the entire sequence is thickened; particularly in the frontal region. The compressive toe region can be likened to an advancing wave; as the mountainous thrust belt advanced the down-surface slope stresses drive thrusts ahead of it much like a surfboard rider. In an attempt to investigate the stresses in the frontal regions of thrustsheets, a numerical method has been devised from the algorithm given by McTigue and Mei [1981]. The algorithm yields a quickly computed approximate solution of the gravity- and tectonic-induced stresses of a two-dimensional homogeneous elastic half-space with an arbitrarily shaped free surface of small slope. A comparison of the numerical method with analytical examples shows excellent agreement. The numerical method was devised because it greatly facilitates the stress calculations and frees one from using the restrictive, simple topographic profiles necessary to obtain an analytical solution. The numerical version of the McTigue and Mei algorithm shows that there is a region of increased maximum resolved shear stress, τ, directly beneath the toe of the overthrust sheet. Utilizing the Mohr-Coulomb failure criterion, predicted fault lines are computed. It is shown that they flatten and become horizontal in some portions of this zone of increased τ. Thrust sheets are known to advance upon weak decollement zones. If there is a coincidence of increased τ, a weak rock layer, and a potential fault line parallel to this weak layer, we have in place all the elements necessary to initiate a new thrusting event. That is, this combination acts as a nucleating center to initiate a new thrusting event. Therefore, thrusts develop in sequence towards the foreland as a consequence of the stress concentrating abilities of the toe of the thrust sheet. The gravity- and tectonic-induced stresses due to the surface topography (usually ignored in previous analyses) of an advancing thrust sheet play a key role in the nature of shallow foreland thrust propagation.

Palinspastic reconstruction of the Alpine thrust belt at the Alpine-Carpathian transition - A geological Sudoku

NASA Astrophysics Data System (ADS)

Beidinger, A.; Decker, K.; Zamolyi, A.; Hölzel, M.; Hoprich, M.; Strauss, P.

2009-04-01

The palinspastic reconstruction of the Austroalpine thrust belt is part of the project Karpatian Tectonics, which is funded by OMV Austria. The objective is to reconstruct the evolution of the thrust belt through the Early to Middle Miocene in order to obtain information on the palaeogeographic position of the Northern Calcareous Alps (NCA) in the region of the present Vienna Basin. A particular goal of the study is to constrain the position of reservoir rocks within the Rhenodanubic Flysch units and the NCA with respect to the autochthonous Malmian source rocks overlying the European basement below the Alpine-Carpathian thrust wedge, and to constrain the burial history of these source rocks. Reconstruction uses regional 2D seismic lines crossing from the European foreland into the fold-thrust belt, 3D seismic data covering the external thrust sheets, and lithostratigraphic data from a total of 51 selected wells, which were drilled and provided by OMV Austria. The main criterion, whether a well was suitable for palinspastic reconstruction or not, was its penetration of Alpine thrust sheets down to the Autochthonous Molasse of the foreland. Additional wells, which do not penetrate the entire Alpine thrust complex but include the Allochthonous Molasse or the external Alpine-Carpathian nappes (Waschberg and Roseldorf thrust unit, Rhenodanubic Flysch nappes) in their well path, were also taken into account. The well data in particular comprise stratigraphic information on the youngest overthrust sediments of the different thrust units and the underlying Autochthonous foreland Molasse. These data allow constraining the timing of thrust events in the allochthonous thrust units and overthrusting of the Autochthonous Molasse. In the particular case of overthrust Autochthonous Molasse, additionally to the timing of overthrusting, which can be derived from the youngest overthrust sediments, the palaeogeographic position of the Alpine Carpathian thrust front could directly be inferred from well data for the specific time period. By further utilization of geological maps, geological cross sections and two regional c. 80 km long composite 2D seismic sections through the external Alpine thrusts, the positions of major thrusts could be approximated for five time slices. This procedure was applied for the front of the allochthonous Molasse units, the floor thrust of the Roseldorf thrust unit, the Waschberg thrust unit and the frontal thrusts of the Rhenodanubic Flysch and the NCA. In addition, several out-of-sequence thrusts within the Waschberg unit, the Molasse unit, the Rhenodanubic Flysch and the Calcareous Alps (floor thrust of the NCA and two internal thrusts) were taken into account. The reconstruction results in 5 palinspastic maps for the time slices early Egerian (25 Ma), early Eggenburgian (20 Ma), Ottnangian (17.5 Ma), Lower Karpatian (16.5 Ma) and the Karpatian/ Badenian stage boundary (16 Ma). Convergence rates, which were calculated for the four intervening time intervals, range from about 3 mm/yr to 5 mm/yr. These values compare well with estimated convergence rates reconstructed for the Miocene in the western Eastern Alps (Schmid et al., 1996), as well as with plate tectonic constraints on Tertiary convergence rates (Dewey et al., 1989). Dewey, J., Helman, M.L., Turco, E., Hutton, D.H.W.&Knott, S.D., 1989. Kinematics of the western Mediterranean, in: N.P. Coward, D. Dietrich & R.G. Park (eds.), Alpine Tectonics, Geol. Soc. Spec. Publ., 45: 265-283. Schmid, S.M., Pfiffner, O.A., Frotzheim, N., Schönborn, G. & Kissling, E., 1996. Geophysical-geological transect and tectonic evolution of the Swiss-Italian Alps. Tectonics, 15: 1036-1064.

Quantifying the high-velocity, low-amplitude spinal manipulative thrust: a systematic review.

PubMed

Downie, Aron S; Vemulpad, Subramanyam; Bull, Peter W

2010-09-01

The purpose of this study was to systematically review studies that quantify the high-velocity, low-amplitude (HVLA) spinal thrust, to qualitatively compare the apparatus used and the force-time profiles generated, and to critically appraise studies involving the quantification of thrust as an augmented feedback tool in psychomotor learning. A search of the literature was conducted to identify the sources that reported quantification of the HVLA spinal thrust. MEDLINE-OVID (1966-present), MANTIS-OVID (1950-present), and CINAHL-EBSCO host (1981-present) were searched. Eligibility criteria included that thrust subjects were human, animal, or manikin and that the thrust type was a hand-delivered HVLA spinal thrust. Data recorded were single force, force-time, or displacement-time histories. Publications were in English language and after 1980. The relatively small number of studies, combined with the diversity of method and data interpretation, did not enable meta-analysis. Twenty-seven studies met eligibility criteria: 17 studies measured thrust as a primary outcome (13 human, 2 cadaver, and 2 porcine). Ten studies demonstrated changes in psychomotor learning related to quantified thrust data on human, manikin, or other device. Quantifiable parameters of the HVLA spinal thrust exist and have been described. There remain a number of variables in recording that prevent a standardized kinematic description of HVLA spinal manipulative therapy. Despite differences in data between studies, a relationship between preload, peak force, and thrust duration was evident. Psychomotor learning outcomes were enhanced by the application of thrust data as an augmented feedback tool. Copyright © 2010 National University of Health Sciences. Published by Mosby, Inc. All rights reserved.

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

Laramide structure of the central Sangre de Cristo Mountains and adjacent Raton Basin, southern Colorado

USGS Publications Warehouse

Lindsey, D.A.

1998-01-01

Laramide structure of the central Sangre de Cristo Mountains (Culebra Range) is interpreted as a system of west-dipping, basement-involved thrusts and reverse faults. The Culebra thrust is the dominant structure in the central part of the range; it dips 30 -55?? west and brings Precambrian metamorphic base-ment rocks over unmetamorphosed Paleozoic rocks. East of the Culebra thrust, thrusts and reverse faults break the basement and overlying cover rocks into north-trending fault blocks; these boundary faults probably dip 40-60?? westward. The orientation of fault slickensides indicates oblique (northeast) slip on the Culebra thrust and dip-slip (ranging from eastward to northward) movement on adjacent faults. In sedimentary cover rocks, east-vergent anticlines overlie and merge with thrusts and reverse faults; these anticlines are interpreted as fault-propagation folds. Minor east-dipping thrusts and reverse faults (backthrusts) occur in both the hanging walls and footwalls of thrusts. The easternmost faults and folds of the Culebra Range form a continuous structural boundary between the Laramide Sangre de Cristo highland and the Raton Basin. Boundary structures consist of west-dipping frontal thrusts flanked on the basinward side by poorly exposed, east-dipping backthrusts. The backthrusts are interpreted to overlie structural wedges that have been emplaced above blind thrusts in the basin margin. West-dipping frontal thrusts and blind thrusts are interpreted to involve basement, but backthrusts are rooted in basin-margin cover rocks. At shallow structural levels where erosion has not exposed a frontal thrust, the structural boundary of the basin is represented by an anticline or monocline. Based on both regional and local stratigraphic evidence, Laramide deformation in the Culebra Range and accompanying synorogenic sedimentation in the western Raton Basin probably took place from latest Cretaceous through early Eocene time. The earliest evidence of uplift and erosion of a highland is the appearance of abundant feldspar in the Late Cretaceous Vermejo Formation. Above the Vermejo, unconformities overlain by conglomerate indicate continued thrusting and erosion of highlands from late Cretaceous (Raton) through Eocene (Cuchara) time. Eocene alluvial-fan conglomerates in the Cuchara Formation may represent erosion of the Culebra thrust block. Deposition in the Raton Basin probably shifted north from New Mexico to southern Colorado from Paleocene to Eocene time as movement on individual thrusts depressed adjacent segments of the basin.

Seismic interpretation and thrust tectonics of the Amadeus Basin, central Australia, along the BMR regional seismic line

NASA Astrophysics Data System (ADS)

Shaw, Russell D.; Korsch, Russell J.; Wright, C.; Goleby, B. R.

At the northern margin of the Amadeus Basin the monoclinal upturn (the MacDonnell Homocline) is interpreted to be the result of rotation and limited back-thrusting of the sedimentary sequence in front of a southerly-directed, imbricate basement thrust-wedge. This thrust complex is linked at depth to the crust-cutting Redbank Thrust Zone. In the northern part of the basin immediately to the south, regional seismic reflection profiling across the Missionary Plain shows a sub-horizontal, north-dipping, parautochthonous sedimentary sequence between about 8.5 km and 12.0 km thick. This sedimentary sequence shows upturning only at the northern and southern extremities, and represents an unusual, relatively undeformed region between converging thrust systems. In this intervening region, the crust appears to have been tilted downwards and northwards in response to the upthrusting to the north. Still farther to the south, the vertical uplift of the southern hanging wall of the Gardiner Thrust is about 6 km. Seismic reflection profiling in the region immediately south of the Gardiner Thrust indicates repetition of the sedimentary sequence. At the far end of the profile, in the Kernot Range, an imbricate thrust system fans ahead of a ramp-flat thrust pair. This thrust system (the Kernot Range Thrust System) occurs immediately north of an aeromagnetic domain boundary which marks the southern limit of a central ridge region characterized by thin Palaeozoic sedimentary cover and shallow depths to magnetic basement. A planar seismic event, imaged to a depth of at least 18 km, may correspond to the same boundary and is interpreted as a pre-basin Proterozoic thrust. Overall, the structure in the shallow sedimentary section in the central-southern region of the Amadeus Basin indicates that north-directed thrusting during the Dovonian-Carboniferous Alice Springs Orogeny was thin-skinned. During this orogeny an earlier thrust system, formed during the Petermann Ranges Orogeny and precursor orogenies in the Late Proterozoic, was reactivated with Proterozoic salt deposits localising the decollement zone. The Alice Springs Orogeny also reactivated a major mid Proterozoic province boundary in the basement to the north of the basin, resulting in major thrust movement at the northern basin margin.

Thrust augmentation nozzle (TAN) concept for rocket engine booster applications

NASA Astrophysics Data System (ADS)

Forde, Scott; Bulman, Mel; Neill, Todd

2006-07-01

Aerojet used the patented thrust augmented nozzle (TAN) concept to validate a unique means of increasing sea-level thrust in a liquid rocket booster engine. We have used knowledge gained from hypersonic Scramjet research to inject propellants into the supersonic region of the rocket engine nozzle to significantly increase sea-level thrust without significantly impacting specific impulse. The TAN concept overcomes conventional engine limitations by injecting propellants and combusting in an annular region in the divergent section of the nozzle. This injection of propellants at moderate pressures allows for obtaining high thrust at takeoff without overexpansion thrust losses. The main chamber is operated at a constant pressure while maintaining a constant head rise and flow rate of the main propellant pumps. Recent hot-fire tests have validated the design approach and thrust augmentation ratios. Calculations of nozzle performance and wall pressures were made using computational fluid dynamics analyses with and without thrust augmentation flow, resulting in good agreement between calculated and measured quantities including augmentation thrust. This paper describes the TAN concept, the test setup, test results, and calculation results.

Shooting Star Experiment

NASA Technical Reports Server (NTRS)

1997-01-01

The Shooting Star Experiment (SSE) is designed to develop and demonstrate the technology required to focus the sun's energy and use the energy for inexpensive space Propulsion Research. Pictured is an engineering model (Pathfinder III) of the Shooting Star Experiment (SSE). This model was used to test and characterize the motion and deformation of the structure caused by thermal effects. In this photograph, alignment targets are being placed on the engineering model so that a theodolite (alignment telescope) could be used to accurately measure the deformation and deflections of the engineering model under extreme conditions, such as the coldness of deep space and the hotness of the sun as well as vacuum. This thermal vacuum test was performed at the X-Ray Calibration Facility because of the size of the test article and the capabilities of the facility to simulate in-orbit conditions

Planetary Habitability

NASA Technical Reports Server (NTRS)

Kasting, James F.

1997-01-01

This grant was entitled 'Planetary Habitability' and the work performed under it related to elucidating the conditions that lead to habitable, i.e. Earth-like, planets. Below are listed publications for the past two and a half years that came out of this work. The main thrusts of the research involved: (1) showing under what conditions atmospheric O2 and O3 can be considered as evidence for life on a planet's surface; (2) determining whether CH4 may have played a role in warming early Mars; (3) studying the effect of varying UV levels on Earth-like planets around different types of stars to see whether this would pose a threat to habitability; and (4) studying the effect of chaotic obliquity variations on planetary climates and determining whether planets that experienced such variations might still be habitable. Several of these topics involve ongoing research that has been carried out under a new grant number, but which continues to be funded by NASA's Exobiology program.

Space Trajectory Error Analysis Program (STEAP) for halo orbit missions. Volume 2: Programmer's manual

NASA Technical Reports Server (NTRS)

Byrnes, D. V.; Carney, P. C.; Underwood, J. W.; Vogt, E. D.

1974-01-01

The six month effort was responsible for the development, test, conversion, and documentation of computer software for the mission analysis of missions to halo orbits about libration points in the earth-sun system. The software consisting of two programs called NOMNAL and ERRAN is part of the Space Trajectories Error Analysis Programs. The program NOMNAL targets a transfer trajectory from earth on a given launch date to a specified halo orbit on a required arrival date. Either impulsive or finite thrust insertion maneuvers into halo orbit are permitted by the program. The transfer trajectory is consistent with a realistic launch profile input by the user. The second program ERRAN conducts error analyses of the targeted transfer trajectory. Measurements including range, doppler, star-planet angles, and apparent planet diameter are processed in a Kalman-Schmidt filter to determine the trajectory knowledge uncertainty.

Generation of buckle folds in Naga fold thrust belt, north-east India

NASA Astrophysics Data System (ADS)

Saha, B.; Dietl, C.

2009-04-01

Naga fold thrust belt (NFTB), India, formed as a result of northward migration of the Indian plate initiated in Eocene and its subsequent collision with the Burmese plate during Oligocene. The NW-SE oriented compression generated a spectrum of structures; among them, we intend to focus on the folds- varying from gentle to tight asymmetric in geometry. Large recumbent folds are often associated with thrusting. Buckle folds forming under shallow crustal conditions are frequently reported from NFTB. Buckle folding occurs mainly within sandstones with intercalated shale layers which are in the study area typical for the Barail, Surma and Tipam Groups. We have tried to explain the controlling factors behind the variation of the buckle fold shapes and their varying wavelengths throughout the fold thrust belt with the aid of analogue (sand box) modelling. It is undoubted that competence contrast along with the layer parallel compressive stress are the major influencing factors in generation of buckle folds. Schmalholz and Podladchikov (1999) and Jeng et al. (2002) have shown that when low strain rate and low temperature are applicable, not only the viscosity contrast, but also the elasticity contrast govern the geometry of the developing buckle folds. Rocks deforming under high temperature and high pressure deform in pure viscous manner, whereas, rocks undergoing less confining stress and less temperature, are subjected to pure elastic deformation. However, they are the end members, and most of the deformations are a combination of these two end members, i.e. of viscoelastic nature. Our models are made up of sieved sand (0.5 mm grain size) and mica layers (1-5 mm) This interlayering imparts a mechanical anisotropy in the model. Mica is not a pure viscous material, rather it displays more elastic behaviour. The mica layers in the model produce bedding parallel slip during shortening through internal reorganization of the individual mica crystals leading to the thickening of the layer. The experiments are performed in a low stress and low temperature environment (ambient temperature being room temperature). The models produce a spectrum of fold shapes ranging from tight asymmetric to gentle. The folds generate initially as gentle folds with rounded hinges in the thick incompetent mica layers and box folds in the thin incompetent mica layers. Thrusts develop and grow by intersecting the existing fold limbs. With incremental compression, the folds become tighter. The thin mica layer is more affected by thrusting than the thicker layer. Our models have a clear advantage of using mixed layer models (sand + mica) over that of pure sand models, because mica accommodates the applied stress both by folding and thrusting. The pure sand models fail to reflect the subtle competence contrast and thus the buckle folds though they excellently simulate the upper crustal layer deformation through thrusting. From our experiments we infer that the difference in fold and thrust morphology is governed by the interplay of two main factors; namely: degree of competence contrast and thickness of competent unit. High mechanical anisotropy give rise to box folds with steep straight limbs, horizontal hinge and conjugate axial planes when the competent unit is a thick one; whereas comparatively low mechanical anisotropy generates rounded buckle fold when the competent unit is a thin one. The geometry of the buckle folds in the NFTB are in good agreement with our experimentally produced buckle folds. The competence contrast throughout the belt has been consistent, only minor variations of sand-shale content have been observed. The competence contrast remaining more or less constant throughout the region, the variable thickness of the stratigraphic units plays a significant role in determining the fold shape. The thicker incompetent units give rise to rounded tight folds and the thinner ones to open box shaped folds, both modified by simultaneously or later generated thrusts. This coexistence of folds as well as thrusts developing simultaneously has been well demonstrated with our models. Therefore, our modelling results give insight into the folding process and the occurrence of differing buckle fold geometry across the NFTB. Reference: Jeng F. S., Lin M.L., Lai Y.C., Teng M.H., 2002. Influence of strain rate on buckle folding of an elasto-viscous single layer. Journal of Structural Geology 24, 501-516. Schmalholz S.M., Podladchikov, Y.Y., 1999. Buckling versus folding: importance of viscoelasticity. Geophysical Research Letters 26, 2641-2644.

Architecture-Led Safety Process

DTIC Science & Technology

2016-12-01

Action Hazard Guide 42 Table 18: Comparative Table of Safety and Reliability Terms 47 CMU/SEI-2016-TR-012 | SOFTWARE ENGINEERING INSTITUTE...provides too much thrust Engine is slow to pro- vide commanded thrust (increase or de- crease) Engine will not shut- down when com - manded...Thrust level must be provided at the com - manded level H4: Engine is slow to provide commanded thrust SC3: Engine must provide commanded thrust in

Statistical error model for a solar electric propulsion thrust subsystem

NASA Technical Reports Server (NTRS)

Bantell, M. H.

1973-01-01

The solar electric propulsion thrust subsystem statistical error model was developed as a tool for investigating the effects of thrust subsystem parameter uncertainties on navigation accuracy. The model is currently being used to evaluate the impact of electric engine parameter uncertainties on navigation system performance for a baseline mission to Encke's Comet in the 1980s. The data given represent the next generation in statistical error modeling for low-thrust applications. Principal improvements include the representation of thrust uncertainties and random process modeling in terms of random parametric variations in the thrust vector process for a multi-engine configuration.

Investigation of Thrust Augmentation of a 1600-pound Thrust Centrifugal-flow-type Turbojet Engine by Injection of Refrigerants at Compressor Inlets

NASA Technical Reports Server (NTRS)

Jones, William L.; Dowman, Harry W.

1947-01-01

Investigations were conducted to determine effectiveness of refrigerants in increasing thrust of turbojet engines. Mixtures of water an alcohol were injected for a range of total flows up to 2.2 lb/sec. Kerosene was injected into inlets covering a range of injected flows up to approximately 30% of normal engine fuel flow. Injection of 2.0 lb/sec of water alone produced an increase in thrust of 35.8% of rate engine conditions and kerosene produced a negligible increase in thrust. Carbon dioxide increased thrust 23.5 percent.

Direct thrust measurement of a permanent magnet helicon double layer thruster

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

Takahashi, K.; Lafleur, T.; Charles, C.

2011-04-04

Direct thrust measurements of a permanent magnet helicon double layer thruster have been made using a pendulum thrust balance and a high sensitivity laser displacement sensor. At the low pressures used (0.08 Pa) an ion beam is detected downstream of the thruster exit, and a maximum thrust force of about 3 mN is measured for argon with an rf input power of about 700 W. The measured thrust is proportional to the upstream plasma density and is in good agreement with the theoretical thrust based on the maximum upstream electron pressure.

Reinterpretation of Mesozoic and Cenozoic tectonic events, Mountain Pass area, northeastern San Bernardino County, California

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

Nance, M.A.

1993-04-01

Detailed mapping, stratigraphic structural analysis in the Mountain Pass area has resulted in a reinterpretation of Mesozoic and Cenozoic tectonic events in the area. Mesozoic events are characterized by north vergent folds and thrust faults followed by east vergent thrusting. Folding created two synclines and an anticline which were than cut at different stratigraphic levels by subsequent thrust faults. Thrusting created composite tectono-stratigraphic sections containing autochthonous, para-autothonous, and allochthonous sections. Normal faults cutting these composite sections including North, Kokoweef, White Line, and Piute fault must be post-thrusting, not pre-thrusting as in previous interpretations. Detailed study of these faults results inmore » differentiation of at least three orders of faults and suggest they represent Cenozoic extension correlated with regional extensional events between 11 and 19 my. Mesozoic stratigraphy reflects regional orogenic uplift, magmatic activity, and thrusting. Inclusion of Kaibab clasts in the Chinle, Kaibab and Chinle clasts in the Aztec, and Chinle, Aztec, and previously deposited Delfonte Volcanics clasts in the younger members of the Delfonte Volcanics suggest regional uplift prior to the thrusting of Cambrian Bonanza King over Delfonte Volcanics by the Mescal Thrust fault. The absence of clasts younger than Kaibab argues against pre-thrusting activity for the Kokoweef fault.« less

An Extended Kalman Filter-Based Attitude Tracking Algorithm for Star Sensors

PubMed Central

Li, Jian; Wei, Xinguo; Zhang, Guangjun

2017-01-01

Efficiency and reliability are key issues when a star sensor operates in tracking mode. In the case of high attitude dynamics, the performance of existing attitude tracking algorithms degenerates rapidly. In this paper an extended Kalman filtering-based attitude tracking algorithm is presented. The star sensor is modeled as a nonlinear stochastic system with the state estimate providing the three degree-of-freedom attitude quaternion and angular velocity. The star positions in the star image are predicted and measured to estimate the optimal attitude. Furthermore, all the cataloged stars observed in the sensor field-of-view according the predicted image motion are accessed using a catalog partition table to speed up the tracking, called star mapping. Software simulation and night-sky experiment are performed to validate the efficiency and reliability of the proposed method. PMID:28825684

An Extended Kalman Filter-Based Attitude Tracking Algorithm for Star Sensors.

PubMed

Li, Jian; Wei, Xinguo; Zhang, Guangjun

2017-08-21

Efficiency and reliability are key issues when a star sensor operates in tracking mode. In the case of high attitude dynamics, the performance of existing attitude tracking algorithms degenerates rapidly. In this paper an extended Kalman filtering-based attitude tracking algorithm is presented. The star sensor is modeled as a nonlinear stochastic system with the state estimate providing the three degree-of-freedom attitude quaternion and angular velocity. The star positions in the star image are predicted and measured to estimate the optimal attitude. Furthermore, all the cataloged stars observed in the sensor field-of-view according the predicted image motion are accessed using a catalog partition table to speed up the tracking, called star mapping. Software simulation and night-sky experiment are performed to validate the efficiency and reliability of the proposed method.

Massive Stars as Cosmic Engines Through the Ages

NASA Astrophysics Data System (ADS)

Maeder, André; Meynet, Georges; Ekström, Sylvia; Hirschi, Raphael; Georgy, Cyril

2008-06-01

Some useful developments in the model physics are briefly presented, followed by model results on chemical enrichments and WR stars. We discuss the expected rotation velocities of WR stars. We emphasize that the (C+O)/He ratio is a better chemical indicator of evolution for WC stars than the C/He ratios. With or without rotation, at a given luminosity the (C+O)/He ratios should be higher in regions of lower metallicity Z. Also, for a given (C+O)/He ratio the WC stars in lower Z regions have higher luminosities. The WO stars, which are likely the progenitors of supernovae SNIc and of some GRBs, should preferentially be found in regions of low Z and be the descendants of very high initial masses. Finally, we emphasize the physical reasons why massive rotating low Z stars may also experience heavy mass loss.

Small star trackers for modern space vehicles

NASA Astrophysics Data System (ADS)

Kouzmin, Vladimir; Jushkov, Vladimir; Zaikin, Vladimir

2017-11-01

Based on experience of many years creation of spacecrafts' star trackers with diversified detectors (from the first star trackers of 60's to tens versions of star trackers in the following years), using technological achievements in the field of optics and electronics the NPP "Geofizika-Cosmos" has provided celestial orientation for all the space vehicles created in Russia and now has developed a series of new star trackers with CCD matrix and special processors, which are able to meet needs in celestial orientation of the modern spacecrafts for the nearest 10-15 years. In the given article the main characteristics and description of some star trackers' versions are presented. The star trackers have various levels of technical characteristics and use both combined (Russian and foreign) procurement parts, and only national (Russian) procurement parts for the main units.

A surprising chill before the cosmic dawn

NASA Astrophysics Data System (ADS)

Greenhill, Lincoln

2018-03-01

An experiment to estimate when stars began to form in the Universe suggests that gas temperatures just before stars appeared had fallen well below predicted limits, and that dark matter is not as shadowy as was thought.

Simple Activities for Powerful Impact

NASA Astrophysics Data System (ADS)

LaConte, K.; Shupla, C. B.; Dusenbery, P.; Harold, J. B.; Holland, A.

2016-12-01

STEM education is having a transformational impact on libraries across the country. The STAR Library Education Network (STAR_Net) provides free Science-Technology Activities & Resources that are helping libraries to engage their communities in STEM learning experiences. Hear the results of a national 2015 survey of library and STEM professionals and learn what STEM programming is currently in place in public libraries and how libraries approach and implement STEM programs. Experience hands-on space science activities that are being used in library programs with multiple age groups. Through these hands-on activities, learners explore the nature of science and employ science and engineering practices, including developing and using models, planning and carrying out investigations, and engaging in argument from evidence (NGSS Lead States, 2013). Learn how STAR_Net can help you print (free!) mini-exhibits and educator guides. Join STAR_Net's online community and access STEM resources and webinars to work with libraries in your local community.

Exposure Time Optimization for Highly Dynamic Star Trackers

PubMed Central

Wei, Xinguo; Tan, Wei; Li, Jian; Zhang, Guangjun

2014-01-01

Under highly dynamic conditions, the star-spots on the image sensor of a star tracker move across many pixels during the exposure time, which will reduce star detection sensitivity and increase star location errors. However, this kind of effect can be compensated well by setting an appropriate exposure time. This paper focuses on how exposure time affects the star tracker under highly dynamic conditions and how to determine the most appropriate exposure time for this case. Firstly, the effect of exposure time on star detection sensitivity is analyzed by establishing the dynamic star-spot imaging model. Then the star location error is deduced based on the error analysis of the sub-pixel centroiding algorithm. Combining these analyses, the effect of exposure time on attitude accuracy is finally determined. Some simulations are carried out to validate these effects, and the results show that there are different optimal exposure times for different angular velocities of a star tracker with a given configuration. In addition, the results of night sky experiments using a real star tracker agree with the simulation results. The summarized regularities in this paper should prove helpful in the system design and dynamic performance evaluation of the highly dynamic star trackers. PMID:24618776

Ames Coronagraph Experiment: Enabling Missions to Directly Image Exoplanets

NASA Technical Reports Server (NTRS)

Belikov, Ruslan

2014-01-01

Technology to find biomarkers and life on other worlds is rapidly maturing. If there is a habitable planet around the nearest star, we may be able to detect it this decade with a small satellite mission. In the 2030 decade, we will likely know if there is life in our Galactic neighborhood (1000 nearest stars). The Ames Coronagraph Experiment is developing coronagraphic technologies to enable such missions.

Works on theory of flapping wing. [considering boundary layer

NASA Technical Reports Server (NTRS)

Golubev, V. V.

1980-01-01

It is shown mathematically that taking account of the boundary layer is the only way to develop a theory of flapping wings without violating the basic observations and mathematics of hydromechanics. A theory of thrust generation by flapping wings can be developed if the conventional downstream velocity discontinuity surface is replaced with the observed Karman type vortex streets behind a flapping wing. Experiments show that the direction of such vortices is the reverse of that of conventional Karman streets. The streets form by breakdown of the boundary layer. Detailed analysis of the movements of certain birds and insects during flight 'in place' is fully consistent with this theory of the lift, thrust and drag of flapping wings. Further directions for research into flight with flapping wings are indicated.

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.

Experimental investigation of combustor effects on rocket thrust chamber performance

NASA Technical Reports Server (NTRS)

1972-01-01

A design and experimental program to develop special instrumentation systems, design engine hardware, and conduct tests using LOX/GH2 propellants in which the propellant flow stratification was controlled is described. The mixture ratio was varied from 4.6 to 6 overall. The mixture ratios in the core and outer zone were varied from 3.5 to 6 and 5 to 8, respectively. The range in boundary layer coolant was from 0 to 10 percent of the fuel. The nominal chamber pressure and thrust were 225 psia and 7000 pounds, respectively. Pressure and heat flux profiles as well as gas sampling of the exhaust products were obtained. Specific impulse efficiencies of approximately 94 percent and characteristic velocity efficiencies of approximately 97 percent were obtained during the experiments.

High Power Electric Propulsion Using The VASIMR VX-200: A Flight Technology Prototype

NASA Astrophysics Data System (ADS)

Bering, Edgar, III; Longmier, Benjamin; Glover, Tim; Chang-Diaz, Franklin; Squire, Jared; Brukardt, Michael

2008-11-01

The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power magnetoplasma rocket, capable of Isp/thrust modulation at constant power. The plasma is produced by a helicon discharge. The bulk of the energy is added by ion cyclotron resonance heating (ICRH.) Axial momentum is obtained by adiabatic expansion of the plasma in a magnetic nozzle. Thrust/specific impulse ratio control in the VASIMR is primarily achieved by the partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. Ion dynamics in the exhaust were studied using probes, gridded energy analyzers (RPA's), microwave interferometry and optical techniques. Results are summarize from high power ICRH experiments performed on the VX-100 using argon plasma during 2007, and on the VX-200 using argon plasma during 2008. The VX-100 has demonstrated ICRH antenna efficiency >90% and a total coupling efficiency of ˜75%. The rocket performance parameters inferred by integrating the moments of the ion energy distribution corresponds to a thrust of 2 N at an exhaust velocity of 20 km/s with the VX-100 device. The new VX-200 machine is described.

Design and Integration of an Actuated Nose Strake Control System

NASA Technical Reports Server (NTRS)

Flick, Bradley C.; Thomson, Michael P.; Regenie, Victoria A.; Wichman, Keith D.; Pahle, Joseph W.; Earls, Michael R.

1996-01-01

Aircraft flight characteristics at high angles of attack can be improved by controlling vortices shed from the nose. These characteristics have been investigated with the integration of the actuated nose strakes for enhanced rolling (ANSER) control system into the NASA F-18 High Alpha Research Vehicle. Several hardware and software systems were developed to enable performance of the research goals. A strake interface box was developed to perform actuator control and failure detection outside the flight control computer. A three-mode ANSER control law was developed and installed in the Research Flight Control System. The thrust-vectoring mode does not command the strakes. The strakes and thrust-vectoring mode uses a combination of thrust vectoring and strakes for lateral- directional control, and strake mode uses strakes only for lateral-directional control. The system was integrated and tested in the Dryden Flight Research Center (DFRC) simulation for testing before installation in the aircraft. Performance of the ANSER system was monitored in real time during the 89-flight ANSER flight test program in the DFRC Mission Control Center. One discrepancy resulted in a set of research data not being obtained. The experiment was otherwise considered a success with the majority of the research objectives being met.

Oxygen/Alcohol Dual Thrust RCS Engines

NASA Technical Reports Server (NTRS)

Angstadt, Tara; Hurlbert, Eric

1999-01-01

A non-toxic dual thrust RCS engine offers significant operational, safety, and performance advantages to the space shuttle and the next generation RLVs. In this concept, a single engine produces two thrust levels of 25 and 870 lbf. The low thrust level is provided by the spark torch igniter, which, with the addition of 2 extra valves, can also be made to function as a vernier. A dual thrust RCS engine allows 38 verniers to be packaged more efficiently on a vehicle. These 38 vemiers improve translation and reduce cross coupling, thereby providing more pure roll, pitch, and yaw maneuvers of the vehicle. Compared to the 6 vemiers currently on the shuttle, the 38 dual thrust engines would be 25 to 40% more efficient for the same maneuvers and attitude control. The vernier thrust level also reduces plume impingement and contamination concerns. Redundancy is also improved, thereby improving mission success reliability. Oxygen and ethanol are benign propellants which do not create explosive reaction products or contamination, as compared to hypergolic propellants. These characteristics make dual-thrust engines simpler to implement on a non-toxic reaction control system. Tests at WSTF in August 1999 demonstrated a dual-thrust concept that is successful with oxygen and ethanol. Over a variety of inlet pressures and mixture ratios at 22:1 area ratio, the engine produced between 230 and 297 sec Isp, and thrust levels from 8 lbf. to 50 lbf. This paper describes the benefits of dual-thrust engines and the recent results from tests at WSTF.

Emplacement history of a thrust sheet based on analysis of pressure solution cleavage and deformed fossils

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

Protzman, G.M.; Mitra, G.

The emplacement history of a thrust sheet is recorded by the strain accumulated in its hanging wall and footwall. Detailed studies of second order structures and analysis of strain due to pressure solution and plastic deformation allow the authors to determine the deformation history of the Meade thrust in the Idaho - Wyoming thrust belt. Emplacement of the Meade thrust was accompanied by the formation of a series of second order in echelon folds in the footwall. Temporal relations based on detailed structural studies show that these folds, which are confined to the Jurassic Twin Creek Formation, formed progressively inmore » front of the advancing Meade thrust and were successively truncated and overridden by footwall imbricates of the Meade thrust. The Twin Creek Formation in both the hanging wall and footwall of the Meade thrust is penetratively deformed, with a well developed pressure solution cleavage. In addition, plastic strain is recorded by deformed Pentacrinus within fossil hash layers in the Twin Creek. Much of this penetrative deformation took place early in the history of the thrust sheet as layer parallel shortening, and the cleavage and deformed fossils behaved passively during subsequent folding and faulting. The later stages of deformation may be sequentially removed through balancing techniques to track successive steps in the deformation. This strain history, which is typical of an internal thrust sheet, is partly controlled by the lithologies involved, timing between successive thrusts, and the amount of interaction between major faults.« less

Effect of Two Advanced Noise Reduction Technologies on the Aerodynamic Performance of an Ultra High Bypass Ratio Fan

NASA Technical Reports Server (NTRS)

Hughes, Christoper E.; Gazzaniga, John A.

2013-01-01

A wind tunnel experiment was conducted in the NASA Glenn Research Center anechoic 9- by 15-Foot Low-Speed Wind Tunnel to investigate two new advanced noise reduction technologies in support of the NASA Fundamental Aeronautics Program Subsonic Fixed Wing Project. The goal of the experiment was to demonstrate the noise reduction potential and effect on fan model performance of the two noise reduction technologies in a scale model Ultra-High Bypass turbofan at simulated takeoff and approach aircraft flight speeds. The two novel noise reduction technologies are called Over-the-Rotor acoustic treatment and Soft Vanes. Both technologies were aimed at modifying the local noise source mechanisms of the fan tip vortex/fan case interaction and the rotor wake-stator interaction. For the Over-the-Rotor acoustic treatment, two noise reduction configurations were investigated. The results showed that the two noise reduction technologies, Over-the-Rotor and Soft Vanes, were able to reduce the noise level of the fan model, but the Over-the-Rotor configurations had a significant negative impact on the fan aerodynamic performance; the loss in fan aerodynamic efficiency was between 2.75 to 8.75 percent, depending on configuration, compared to the conventional solid baseline fan case rubstrip also tested. Performance results with the Soft Vanes showed that there was no measurable change in the corrected fan thrust and a 1.8 percent loss in corrected stator vane thrust, which resulted in a total net thrust loss of approximately 0.5 percent compared with the baseline reference stator vane set.

Why do airlines want and use thrust reversers? A compilation of airline industry responses to a survey regarding the use of thrust reversers on commercial transport airplanes

NASA Technical Reports Server (NTRS)

Yetter, Jeffrey A.

1995-01-01

Although thrust reversers are used for only a fraction of the airplane operating time, their impact on nacelle design, weight, airplane cruise performance, and overall airplane operating and maintenance expenses is significant. Why then do the airlines want and use thrust reversers? In an effort to understand the airlines need for thrust reversers, a survey of the airline industry was made to determine why and under what situations thrust reversers are currently used or thought to be needed. The survey was intended to help establish the cost/benefits trades for the use of thrust reversers and airline opinion regarding alternative deceleration devices. A compilation and summary of the responses given to the survey questionnaire is presented.

Thrust distribution for attitude control in a variable thrust propulsion system with four ACS nozzles

NASA Astrophysics Data System (ADS)

Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung

2017-04-01

A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.

Optimal thrust level for orbit insertion

NASA Astrophysics Data System (ADS)

Cerf, Max

2017-07-01

The minimum-fuel orbital transfer is analyzed in the case of a launcher upper stage using a constantly thrusting engine. The thrust level is assumed to be constant and its value is optimized together with the thrust direction. A closed-loop solution for the thrust direction is derived from the extremal analysis for a planar orbital transfer. The optimal control problem reduces to two unknowns, namely the thrust level and the final time. Guessing and propagating the costates is no longer necessary and the optimal trajectory is easily found from a rough initialization. On the other hand the initial costates are assessed analytically from the initial conditions and they can be used as initial guess for transfers at different thrust levels. The method is exemplified on a launcher upper stage targeting a geostationary transfer orbit.

Northward laramide thrusting in the quitovac region, northwestern sonora, mexico: Implications for the juxtaposition of paleoproterozoic basement blocks and the mojave-sonora megashear hypothesis

USGS Publications Warehouse

Iriondo, Alexander; Martínez-Torres, Luis M.; Kunk, Michael J.; Atkinson, William W.; Premo, Wayne R.; McIntosh, William C.

2005-01-01

Restoration of 12%–30% Basin and Range extension allows direct interpretation of ductile fabrics associated with a stack of Laramide thrust faults in the Quitovac region in northwestern Sonora. The inferred direction of displacement of these thrusts varies gradually from N63°W to N23°E and is interpreted to represent a clockwise rotation of the direction of Laramide thrusting through time. The thrust faults represent a piggy-back sequence of thrusting propagating north, toward the foreland. The average direction and sense of displacement of the thrusts is N18°W, and the cumulative 45 km of estimated northward-directed displacement corresponds to ∼86% of shortening.Based on geochronological constraints, onset of thrusting in Quitovac occurred sometime between 75 and 61 Ma, whereas cessation occurred at ca. 39 Ma. The presence of Paleocene-Eocene orogenic gold mineralization, spatially associated with thrusting, strengthens our idea that compressional tectonism associated with the Laramide orogeny is a very important and widespread dynamometamorphic event in the region.Similarities in age, kinematics, and structural stratigraphy indicate that the thrusting in the Quitovac region may be equivalent to the Laramide Quitobaquito Thrust in southwestern Arizona. In both areas, thrust faults juxtapose the Paleoproterozoic Caborca and “North America” basement blocks. This juxtaposition was previously proposed as exclusively related to movements along the hypothetical Upper Jurassic Mojave-Sonora megashear. The Laramide northward displacements and clockwise rotations recorded in the Caborca block rocks in Quitovac contradict the southward displacements (∼800 km) and counterclockwise rotations inherent in the left-lateral Upper Jurassic Mojave-Sonora megashear hypothesis. We conclude that if this megashear exists in northwestern Sonora, its trace should be to the southwest of the Quitovac region.

Cold Dust and its Heating Sources in M 33

NASA Astrophysics Data System (ADS)

Komugi, Shinya; Tosaki, Tomoka; Kohno, Kotaro; Tsukagoshi, Takashi; Tamura, Yoichi; Miura, Rie; Onodera, Sachiko; Kuno, Nario; Kawabe, Ryohei; Nakanishi, Koichiro; Sawada, Tsuyoshi; Ezawa, Hajime; Wilson, Grant W.; Yun, Min S.; Scott, Kimberly S.; Hughes, David H.; Aretxaga, Itziar; Perera, Thushara A.; Austermann, Jason E.; Tanaka, Kunihiko; Muraoka, Kazuyuki; Egusa, Fumi

2011-12-01

We have mapped the nearby face-on spiral galaxy M 33 in the 1.1 mm dust continuum using AzTEC on Atacama Submillimeter Telescope Experiment (ASTE). The preliminary results are presented here. The observed dust has a characteristic temperature of ~ 21 K in the central kpc, radially declining down to ~ 13 K at the edge of the star forming disk. We compare the dust temperatures with KS band flux and star formation tracers. Our results imply that cold dust heating may be driven by long-lived stars even nearby star forming regions.

The LUNA experiment at Gran Sasso Laboratory: Studying stars by going underground

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

Guglielmetti, Alessandra

2015-10-15

Accurate knowledge of thermonuclear reaction rates is a key issue in nuclear astrophysics: it is important for understanding the energy generation, neutrino production and the synthesis of the elements in stars and during primordial nucleosynthesis. Cross-section measurements are mainly hampered by the very low counting rate and cosmic background. An underground location is extremely advantageous for such studies, as demonstrated by the LUNA experiment in the Gran Sasso Laboratory (Italy). This paper reports on the results recently obtained by this experiment and on the future perspectives in the field.

Tests of the gravitational redshift effect in space-born and ground-based experiments

NASA Astrophysics Data System (ADS)

Vavilova, I. B.

2018-02-01

This paper provides a brief overview of experiments as concerns with the tests of the gravitational redshift (GRS) effect in ground-based and space-born experiments. In particular, we consider the GRS effects in the gravitational field of the Earth, the major planets of the Solar system, compact stars (white dwarfs and neutron stars) where this effect is confirmed with a higher accuracy. We discuss availabilities to confirm the GRS effect for galaxies and galaxy clusters in visible and X-ray ranges of the electromagnetic spectrum.

Dwarf Star Erupts in Giant Flare

NASA Technical Reports Server (NTRS)

2005-01-01

This movie taken by NASA'S Galaxy Evolution Explorer shows one of the largest flares, or star eruptions, ever recorded at ultraviolet wavelengths. The star, called GJ 3685A, just happened to be in the Galaxy Evolution Explorer's field of view while the telescope was busy observing galaxies. As the movie demonstrates, the seemingly serene star suddenly exploded once, then even more intensely a second time, pouring out in total about one million times more energy than a typical flare from our Sun. The second blast of light constituted an increase in brightness by a factor of at least 10,000.

Flares are huge explosions of energy stemming from a single location on a star's surface. They are caused by the brief destruction of a star's magnetic fields. Many types of stars experience them, though old, small, rapidly rotating 'red dwarfs' like GJ 3685A tend to flare more frequently and dramatically. These stars, called flare stars, can experience powerful eruptions as often as every few hours. Younger stars, in general, also erupt more often. One of the reasons astronomers study flare stars is to gain a better picture and history of flare events taking place on the Sun.

A preliminary analysis of the GJ 3685A flare shows that the mechanisms underlying stellar eruptions may be more complex than previously believed. Evidence for the two most popular flare theories was found.

Though this movie has been sped up (the actual flare lasted about 20 minutes), time-resolved data exist for each one-hundredth of a second. These observations were taken at 2 p.m. Pacific time, April 24, 2004. In the still image, the time sequence starts in the upper left panel, continues in the upper right, then moves to the lower left and ends in the lower right.

The circular and linear features that appear below and to the right of GJ 3685A during the flare event are detector artifacts caused by the extreme brightness of the flare.

Scaled Eagle Nebula Experiments on NIF

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

Pound, Marc W.

We performed scaled laboratory experiments at the National Ignition Facility laser to assess models for the creation of pillar structures in star-forming clouds of molecular hydrogen, in particular the famous Pillars of the Eagle Nebula. Because pillars typically point towards nearby bright ultraviolet stars, sustained directional illumination appears to be critical to pillar formation. The experiments mock up illumination from a cluster of ultraviolet-emitting stars, using a novel long duration (30--60 ns), directional, laser-driven x-ray source consisting of multiple radiation cavities illuminated in series. Our pillar models are assessed using the morphology of the Eagle Pillars observed with the Hubblemore » Space Telescope, and measurements of column density and velocity in Eagle Pillar II obtained at the BIMA and CARMA millimeter wave facilities. In the first experiments we assess a shielding model for pillar formation. The experimental data suggest that a shielding pillar can match the observed morphology of Eagle Pillar II, and the observed Pillar II column density and velocity, if augmented by late time cometary growth.« less

Scaled Lunar Module Jet Erosion Experiments

NASA Technical Reports Server (NTRS)

Land, Norman S.; Scholl, Harland F.

1966-01-01

An experimental research program was conducted on the erosion of particulate surfaces by a jet exhaust. These experiments were scaled to represent the lunar module (LM) during landing. A conical cold-gas nozzle simulating the lunar module nozzle was utilized. The investigation was conducted within a large vacuum chamber by using gravel or glass beads as a simulated soil. The effects of thrust, descent speed, nozzle terminal height, particle size on crater size, and visibility during jet erosion were determined.

Thrust rollers

NASA Technical Reports Server (NTRS)

Vranish, John M. (Inventor)

2007-01-01

A thrust roller bearing system comprising an inner rotating member, an outer rotating member and multiple rollers coupling the inner rotating member with outer rotating member. The inner and outer rotating members include thrust lips to enable the rollers to act as thrust rollers. The rollers contact inner and outer rotating members at bearing contact points along a contact line. Consequently, the radial/tilt and thrust forces move synchronously and simultaneously to create a bearing action with no slipping.

Transiting circumbinary planets Kepler-34 b and Kepler-35 b

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

Welsh, William F.; Orosz, Jerome A.; Carter, Joshua A.

Most Sun-like stars in the Galaxy reside in gravitationally-bound pairs of stars called 'binary stars'. While long anticipated, the existence of a 'circumbinary planet' orbiting such a pair of normal stars was not definitively established until the discovery of Kepler-16. Incontrovertible evidence was provided by the miniature eclipses ('transits') of the stars by the planet. However, questions remain about the prevalence of circumbinary planets and their range of orbital and physical properties. Here we present two additional transiting circumbinary planets, Kepler-34 and Kepler-35. Each is a low-density gas giant planet on an orbit closely aligned with that of its parentmore » stars. Kepler-34 orbits two Sun-like stars every 289 days, while Kepler-35 orbits a pair of smaller stars (89% and 81% of the Sun's mass) every 131 days. Due to the orbital motion of the stars, the planets experience large multi-periodic variations in incident stellar radiation. The observed rate of circumbinary planets implies > ~1% of close binary stars have giant planets in nearly coplanar orbits, yielding a Galactic population of at least several million.« less

STAR: Preparing future science and math teachers through authentic research experiences at national laboratories

NASA Astrophysics Data System (ADS)

Keller, John; Rebar, Bryan

2012-11-01

The STEM Teacher and Researcher (STAR) Program provides 9-week paid summer research experiences at national research laboratories for future science and math teachers. The program, run by the Cal Poly Center for Excellence in Science and Mathematics Education (CESaME) on behalf of the entire California State University (CSU) System, has arranged 290 research internships for 230 STEM undergraduates and credential candidates from 43 campuses over the past 6 years. The program has partnered with seven Department of Energy labs, four NASA centers, three NOAA facilities, and the National Optical Astronomy Observatory (NOAO). Primary components of the summer experience include a) conducting research with a mentor or mentor team, b) participating in weekly 2-3 hour workshops focused on translating lessons learned from summer research into classroom practice, and c) presenting a research poster or oral presentation and providing a lesson plan linked to the summer research experience. The central premise behind the STAR Program is that future science and math teachers can more effectively prepare the next generation of science, math, and engineering students if they themselves have authentic experiences as researchers.

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.

Back-thrusting in Lesser Himalaya: Evidences from magnetic fabric studies in parts of Almora crystalline zone, Kumaun Lesser Himalaya

NASA Astrophysics Data System (ADS)

Agarwal, Amar; Agarwal, K. K.; Bali, R.; Prakash, Chandra; Joshi, Gaurav

2016-06-01

The present study aims to understand evolution of the Lesser Himalaya, which consists of (meta) sedimentary and crystalline rocks. Field studies, microscopic and rock magnetic investigations have been carried out on the rocks near the South Almora Thrust (SAT) and the North Almora Thrust (NAT), which separates the Almora Crystalline Zone (ACZ) from the Lesser Himalayan sequences (LHS). The results show that along the South Almora Thrust, the deformation is persistent; however, near the NAT deformation pattern is complex and implies overprinting of original shear sense by a younger deformational event. We attribute this overprinting to late stage back-thrusting along NAT, active after the emplacement of ACZ. During this late stage back-thrusting, rocks of the ACZ and LHS were coupled. Back-thrusts originated below the Lesser Himalayan rocks, probably from the Main Boundary Thrust, and propagated across the sedimentary and crystalline rocks. This study provides new results from multiple investigations, and enhances our understanding of the evolution of the ACZ.

Tatooines Future: The Eccentric Response of Keplers Circumbinary Planets to Common-Envelope Evolution of their Host Stars

NASA Technical Reports Server (NTRS)

Kostov, Veselin B.; Moore, Keavin; Tamayo, Daniel; Jayawardhana, Ray; Rinehart, Stephen A.

2016-01-01

Inspired by the recent Kepler discoveries of circumbinary planets orbiting nine close binary stars, we explore the fate of the former as the latter evolve off the main sequence. We combine binary star evolution models with dynamical simulations to study the orbital evolution of these planets as their hosts undergo common-envelope stages, losing in the process a tremendous amount of mass on dynamical timescales. Five of the systems experience at least one Roche-lobe overflow and common-envelope stages (Kepler-1647 experiences three), and the binary stars either shrink to very short orbits or coalesce; two systems trigger a double-degenerate supernova explosion. Kepler's circumbinary planets predominantly remain gravitationally bound at the end of the common-envelope phase, migrate to larger orbits, and may gain significant eccentricity; their orbital expansion can be more than an order of magnitude and can occur over the course of a single planetary orbit. The orbits these planets can reach are qualitatively consistent with those of the currently known post-common-envelope, eclipse-time variations circumbinary candidates. Our results also show that circumbinary planets can experience both modes of orbital expansion (adiabatic and non-adiabatic) if their host binaries undergo more than one common-envelope stage; multiplanet circumbinary systems like Kepler-47 can experience both modes during the same common-envelope stage. Additionally, unlike Mercury orbiting the Sun, a circumbinary planet with the same semi-major axis can survive the common envelope evolution of a close binary star with a total mass of 1 Solar Mass.

Information Provision in Emergency Settings: The Experience of Refugee Communities in Zambia

ERIC Educational Resources Information Center

Kanyengo, Brendah Kakulwa; Kanyengo, Christine Wamunyima

2011-01-01

This article identifies information provision services in emergency settings using Zambia as a case study by identifying innovative ways of providing library and information services. The thrust of the article is to analyze information management practices of organizations that work within refugee camps and how they take specific cognizance of the…

14 CFR 33.201 - Design and test requirements for Early ETOPS eligibility.

Code of Federal Regulations, 2010 CFR

2010-01-01

... maintenance errors that could result in an IFSD, loss of thrust control, or other power loss. (b) The design... power loss in the applicant's other relevant type designs approved within the past 10 years, to the... service data must show experience with and knowledge of problem mitigating design practices equivalent to...

Voices of Women in the Field: Lessons from the Land of Administrative Oz

ERIC Educational Resources Information Center

Renner, Carol

2005-01-01

The classic fairy tale, the "Wizard of Oz," may have some lessons for female teachers considering school administration. Just as Dorothy, female educators experience the same perplexing emotions, questioning the right career destiny, experiencing stormy situations that thrust them into career paths, exploring the unpredictable paths to their…

A Social Marketing Campaign in Denver: Reducing the Risk of Elder Fraud

ERIC Educational Resources Information Center

McKenna, Judy; Miller, Jacque; Curtis, Lisa

2004-01-01

Acknowledging the pain and loss senior citizens experience due to fraud, the Denver District Attorney's Office launched a campaign--"Clergy Against Senior Exploitation (CASE)"--to reduce fraud perpetrated on older persons. The thrust of this project was preventing fraud by educating older adults through their religious affiliations in…

Magnetohydrodynamic Augmented Propulsion Experiment: I. Performance Analysis and Design

NASA Technical Reports Server (NTRS)

Litchford, R. J.; Cole, J. W.; Lineberry, J. T.; Chapman, J. N.; Schmidt, H. J.; Lineberry, C. W.

2003-01-01

The performance of conventional thermal propulsion systems is fundamentally constrained by the specific energy limitations associated with chemical fuels and the thermal limits of available materials. Electromagnetic thrust augmentation represents one intriguing possibility for improving the fuel composition of thermal propulsion systems, thereby increasing overall specific energy characteristics; however, realization of such a system requires an extremely high-energy-density electrical power source as well as an efficient plasma acceleration device. This Technical Publication describes the development of an experimental research facility for investigating the use of cross-field magnetohydrodynamic (MHD) accelerators as a possible thrust augmentation device for thermal propulsion systems. In this experiment,a 1.5-MW(sub e) Aerotherm arc heater is used to drive a 2-MW(sub e) MHD accelerator. The heatsink MHD accelerator is configured as an externally diagonalized, segmented channel, which is inserted into a large-bore, 2-T electromagnet. The performance analysis and engineering design of the flow path are described as well as the parameter measurements and flow diagnostics planned for the initial series of test runs.

Experimental Study of an Axisymmetric Dual Throat Fluidic Thrust Vectoring Nozzle for Supersonic Aircraft Application

NASA Technical Reports Server (NTRS)

Flamm, Jeffrey D.; Deere, Karen A.; Mason, Mary L.; Berrier, Bobby L.; Johnson, Stuart K.

2007-01-01

An axisymmetric version of the Dual Throat Nozzle concept with a variable expansion ratio has been studied to determine the impacts on thrust vectoring and nozzle performance. The nozzle design, applicable to a supersonic aircraft, was guided using the unsteady Reynolds-averaged Navier-Stokes computational fluid dynamics code, PAB3D. The axisymmetric Dual Throat Nozzle concept was tested statically in the Jet Exit Test Facility at the NASA Langley Research Center. The nozzle geometric design variables included circumferential span of injection, cavity length, cavity convergence angle, and nozzle expansion ratio for conditions corresponding to take-off and landing, mid climb and cruise. Internal nozzle performance and thrust vectoring performance was determined for nozzle pressure ratios up to 10 with secondary injection rates up to 10 percent of the primary flow rate. The 60 degree span of injection generally performed better than the 90 degree span of injection using an equivalent injection area and number of holes, in agreement with computational results. For injection rates less than 7 percent, thrust vector angle for the 60 degree span of injection was 1.5 to 2 degrees higher than the 90 degree span of injection. Decreasing cavity length improved thrust ratio and discharge coefficient, but decreased thrust vector angle and thrust vectoring efficiency. Increasing cavity convergence angle from 20 to 30 degrees increased thrust vector angle by 1 degree over the range of injection rates tested, but adversely affected system thrust ratio and discharge coefficient. The dual throat nozzle concept generated the best thrust vectoring performance with an expansion ratio of 1.0 (a cavity in between two equal minimum areas). The variable expansion ratio geometry did not provide the expected improvements in discharge coefficient and system thrust ratio throughout the flight envelope of typical a supersonic aircraft. At mid-climb and cruise conditions, the variable geometry design compromised thrust vector angle achieved, but some thrust vector control would be available, potentially for aircraft trim. The fixed area, expansion ratio of 1.0, Dual Throat Nozzle provided the best overall compromise for thrust vectoring and nozzle internal performance over the range of NPR tested compared to the variable geometry Dual Throat Nozzle.

Limited fluid in carbonate-shale hosted thrust faults of the Rocky Mountain Fold-and-Thrust Belt (Sun River Canyon, Montana)

NASA Astrophysics Data System (ADS)

OBrien, V. J.; Kirschner, D. L.

2001-12-01

It is widely accepted that fluids play a fundamental role in the movement of thrust faults in foreland fold-and-thrust belts. We have begun a combined structure-geochemistry study of faults in the Rocky Mountain fold-and-thrust belt in order to provide more insight into the occurrence and role(s) of fluid in the deformation of thrust faults. We focus on faults exposed in the Sun River Canyon of Montana, an area that contains some of the best exposures of the Rocky Mountain fold-and-thrust belt in the U.S. Samples were collected from two well exposed thrusts in the Canyon -- the Diversion and French thrusts. Both faults have thrust Mississippian dolostones over Cretaceous shales. Displacement exceeds several kilometers. Numerous small-displacement, subsidiary faults characterize the deformation in the hanging wall carbonates. The footwall shales accommodated more penetrative deformation, resulting in well developed foliation and small-scale folds. Stable isotope data have been obtained from host rock samples and veins from these faults. The data delimit an arcuate trend in oxygen-carbon isotope space. Approximately 50 host rock carbonate samples from the hanging walls have carbon and oxygen isotope values ranging from +3 to 0 and 28 to 19 per mil, respectively. There is no apparent correlation between isotopic values and distance from thrust fault at either locality. Fifteen samples of fibrous slickensides on small-displacement faults in the hanging walls have similar carbon and lower oxygen isotope values (down to 16 per mil). And 15 veins that either post-date thrusting or are of indeterminate origin have carbon and oxygen isotope values down to -3 and12 per mil, respectively. The isotopic data collected during the initial stages of this project are similar to some results obtained several hundred kilometers north in the Front Ranges of the Canadian Rockies (Kirschner and Kennedy, JGR 2000) and in carbonate fold-thrust belts of the Swiss Helvetic Alps and Italian Apennines. These data are consistent with limited infiltration of fluid through fractures and minor faults into hanging walls of large-displacement thrust faults.

Oscillating Red Giants Observed during Campaign 1 of the Kepler K2 Mission: New Prospects for Galactic Archaeology

NASA Astrophysics Data System (ADS)

Stello, Dennis; Huber, Daniel; Sharma, Sanjib; Johnson, Jennifer; Lund, Mikkel N.; Handberg, Rasmus; Buzasi, Derek L.; Silva Aguirre, Victor; Chaplin, William J.; Miglio, Andrea; Pinsonneault, Marc; Basu, Sarbani; Bedding, Tim R.; Bland-Hawthorn, Joss; Casagrande, Luca; Davies, Guy; Elsworth, Yvonne; Garcia, Rafael A.; Mathur, Savita; Di Mauro, Maria Pia; Mosser, Benoit; Schneider, Donald P.; Serenelli, Aldo; Valentini, Marica

2015-08-01

NASA’s re-purposed Kepler mission—dubbed K2—has brought new scientific opportunities that were not anticipated for the original Kepler mission. One science goal that makes optimal use of K2's capabilities, in particular its 360° ecliptic field of view, is galactic archaeology—the study of the evolution of the Galaxy from the fossil stellar record. The thrust of this research is to exploit high-precision, time-resolved photometry from K2 in order to detect oscillations in red giant stars. This asteroseismic information can provide estimates of stellar radius (hence distance), mass, and age of vast numbers of stars across the Galaxy. Here we present the initial analysis of a subset of red giants, observed toward the north galactic gap, during the mission’s first full science campaign. We investigate the feasibility of using K2 data for detecting oscillations in red giants that span a range in apparent magnitude and evolutionary state (hence intrinsic luminosity). We demonstrate that oscillations are detectable for essentially all cool giants within the {log}g range ˜1.9-3.2. Our detection is complete down to {\\text{Kp}} ˜ 14.5, which results in a seismic sample with little or no detection bias. This sample is ideally suited to stellar population studies that seek to investigate potential shortcomings of contemporary Galaxy models.

The Living With a Star Space Environment Testbed Payload

NASA Technical Reports Server (NTRS)

Xapsos, Mike

2015-01-01

This presentation outlines a brief description of the Living With a Star (LWS) Program missions and detailed information about the Space Environment Testbed (SET) payload consisting of a space weather monitor and carrier containing 4 board experiments.

Optimal Trajectories For Orbital Transfers Using Low And Medium Thrust Propulsion Systems

NASA Technical Reports Server (NTRS)

Cobb, Shannon S.

1992-01-01

For many problems it is reasonable to expect that the minimum time solution is also the minimum fuel solution. However, if one allows the propulsion system to be turned off and back on, it is clear that these two solutions may differ. In general, high thrust transfers resemble the well-known impulsive transfers where the burn arcs are of very short duration. The low and medium thrust transfers differ in that their thrust acceleration levels yield longer burn arcs which will require more revolutions, thus making the low thrust transfer computational intensive. Here, we consider optimal low and medium thrust orbital transfers.

Aircraft Engine Thrust Estimator Design Based on GSA-LSSVM

NASA Astrophysics Data System (ADS)

Sheng, Hanlin; Zhang, Tianhong

2017-08-01

In view of the necessity of highly precise and reliable thrust estimator to achieve direct thrust control of aircraft engine, based on support vector regression (SVR), as well as least square support vector machine (LSSVM) and a new optimization algorithm - gravitational search algorithm (GSA), by performing integrated modelling and parameter optimization, a GSA-LSSVM-based thrust estimator design solution is proposed. The results show that compared to particle swarm optimization (PSO) algorithm, GSA can find unknown optimization parameter better and enables the model developed with better prediction and generalization ability. The model can better predict aircraft engine thrust and thus fulfills the need of direct thrust control of aircraft engine.

Space Shuttle booster thrust imbalance analysis

NASA Technical Reports Server (NTRS)

Bailey, W. R.; Blackwell, D. L.

1985-01-01

An analysis of the Shuttle SRM thrust imbalance during the steady-state and tailoff portions of the boost phase of flight are presented. Results from flights STS-1 through STS-13 are included. A statistical analysis of the observed thrust imbalance data is presented. A 3 sigma thrust imbalance history versus time was generated from the observed data and is compared to the vehicle design requirements. The effect on Shuttle thrust imbalance from the use of replacement SRM segments is predicted. Comparisons of observed thrust imbalances with respect to predicted imbalances are presented for the two space shuttle flights which used replacement aft segments (STS-9 and STS-13).

An Experimental Investigation of Unsteady Thrust Augmentation Using a Speaker-Driven Jet

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.; Wernet, Mark P.; John, Wentworth T.

2004-01-01

An experimental investigation is described in which a simple speaker-driven jet was used as a pulsed thrust source (driver) for an ejector configuration. The objectives of the investigation were twofold: first, to add to the experimental body of evidence showing that an unsteady thrust source, combined with a properly sized ejector generally yields higher thrust augmentation values than a similarly sized, steady driver of equivalent thrust. Second, to identify characteristics of the unsteady driver that may be useful for sizing ejectors, and predicting what thrust augmentation values may be achieved. The speaker-driven jet provided a convenient source for the investigation because it is entirely unsteady (having no mean component) and because relevant parameters such as frequency, time-averaged thrust, and diameter are easily variable. The experimental setup will be described, as will the various measurements made. These include both thrust and Digital Particle Imaging Velocimetry of the driver. It will be shown that thrust augmentation values as high as 1.8 were obtained, that the diameter of the best ejector scaled with the dimensions of the emitted vortex, and that the so-called Formation Number serves as a useful dimensionless number by which to characterize the jet and predict performance.

The paradox of vertical σ2 in foreland fold and thrust belts

NASA Astrophysics Data System (ADS)

Tavani, Stefano

2014-05-01

Occurrence of aesthetically appealing thrust systems and associated large scale anticlines, in both active and fossil foreland fold and thrust belts, is commonly interpreted as an evidence for Andersonian compressional framework. Indeed, these structures would testify for a roughly vertical σ3. Such a correlation between thrusts occurrence and stress field orientation, however, frequently fails to explain denser observations at a smaller scale. The syn-orogenic deformation meso-structures hosted in exposed km-scale thrust-related folds, in fact, frequently and paradoxically witness for a syn-thrusting strike-slip stress configuration, with a near-vertical σ2 and a sub-horizontal σ3. This apparent widespread inconsistency between syn-orogenic meso-structures and stress field orientation is here named "the σ2 paradox". A possible explanation for such a paradox is provided by inherited extensional deformation structures commonly developed prior to thrusting, in the flexural foreland basins located ahead of fold and thrust belts. Thrust nucleation and propagation is facilitated and driven by the positive inversion of the extensional inheritances, and their subsequent linkage. This process eventually leads to the development of large reverse fault zones and can occur both in compressive and strike-slip stress configurations.

Stratigraphy and structure of the Sevier thrust belt and proximal foreland-basin system in central Utah: A transect from the Sevier Desert to the Wasatch Plateau

USGS Publications Warehouse

Lawton, T.F.; Sprinkel, D.A.; Decelles, P.G.; Mitra, G.; Sussman, A.J.; Weiss, M.P.

1997-01-01

The Sevier orogenic belt in central Utah comprises four north-northwest trending thrust plates and two structural culminations that record crustal shortening and uplift in late Mesozoic and early Tertiary time. Synorogenic clastic rocks, mostly conglomerate and sandstone, exposed within the thrust belt were deposited in wedge-top and foredeep depozones within the proximal part of the foreland-basin system. The geologic relations preserved between thrust structures and synorogenic deposits demonstrate a foreland-breaking sequence of thrust deformation that was modified by minor out-of-sequence thrust displacement. Structural culminations in the interior part of the thrust belt deformed and uplifted some of the thrust sheets following their emplacement. Strata in the foreland basin indicate that the thrust sheets of central Utah were emplaced between latest Jurassic and Eocene time. The oldest strata of the foredeep depozone (Cedar Mountain Formation) are Neocomian and were derived from the hanging wall of the Canyon Range thrust. The foredeep depozone subsided most rapidly during Albian through Santonian or early Campanian time and accumulated about 2.5 km of conglomeratic strata (Indianola Group). The overlying North Horn Formation accumulated in a wedge-top basin from the Campanian to the Eocene and records propagation of the Gunnison thrust beneath the former foredeep. The Canyon Range Conglomerate of the Canyon Mountains, equivalent to the Indianola Group and the North Horn Formation, was deposited exclusively in a wedge-top setting on the Canyon Range and Pavant thrust sheets. This field trip, a three day, west-to-east traverse of the Sevier orogenic belt in central Utah, visits localities where timing of thrust structures is demonstrated by geometry of cross-cutting relations, growth strata associated with faults and folds, or deformation of foredeep deposits. Stops in the Canyon Mountains emphasize geometry of late structural culminations and relationships of the Canyon Range thrust to growth strata deposited in the wedge-top depozone. Stops in the San Pitch Mountains illustrate deposits of the foredeep depozone and younger, superjacent wedge-top depozone. Stops in the Sanpete Valley and western part of the Wasatch Plateau examine the evolution of the foreland-basin system from foredeep to wedge-top during growth of a triangle zone near the front of the Gunnison thrust.

Community pharmacists' beliefs regarding improvement of Star Ratings scores using the Theory of Planned Behavior.

PubMed

George, David L; Smith, Michael J; Draugalis, JoLaine R; Tolma, Eleni L; Keast, Shellie L; Wilson, Justin B

The Centers for Medicare and Medicaid Services (CMS) is moving toward a value-based model, which includes the Five-Star Quality Rating System (Star Ratings). Prescription Drug Plans include multiple pharmacy measures associated with adherence and patient safety that contribute to CMS Star Ratings scores. This study, using the Theory of Planned Behavior (TPB), explored factors associated with community pharmacists' beliefs to improve Star Ratings scores. Exploratory, qualitative, use of focus groups, and the TPB. Focus groups were performed in conference rooms at the College of Pharmacy main and satellite campuses. Participants were community retail pharmacists with an active Oklahoma license and 1 year of work experience. Each focus group was audio recorded and the recording transcribed to documents and analyzed with the use of a hybrid deductive and inductive qualitative approach rooted in a constant comparative framework. Coding of the data back to the TPB constitutes a deductive approach. The generation of themes and subthemes from other coded nodes constitutes an inductive approach. Analysts agreed on common themes, differences in findings, and saturation of the data gathered. Four focus groups were conducted with 26 participants in 2 categories: pharmacists with and without experience improving Star Ratings. Pharmacists shared and contrasted in salient, normative, and control beliefs about patient outcomes, data, financial implications, staff, technology, and other stakeholders associated with performance of improving Star Ratings. Themes regarding medication adherence, patient safety, and intention were also found. The TPB was used to explore beliefs of community pharmacists about improving Star Ratings scores. Themes that were identified will assist in future research for measuring intention to improve CMS Star Ratings scores and the development of training and education programs. Published by Elsevier Inc.

Minimum work analysis on the critical taper accretionary wedges- insights from analogue modeling

NASA Astrophysics Data System (ADS)

Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

2014-05-01

The Critical taper theory (CTT) is a fundamental concept for the understanding of mountain building processes. Based on force balance it predicts the preferred steady state geometry of an accretionary wedge system and its tectonic regime (extensive, compressive, stable). However, it does not specify which structures are formed and reactivated to reach the preferred state. The latter can be predicted by the minimum work concept. Here we test both concepts and their interplay by analysing two simple sand wedge models which differ only in the thickness of the basal detachment (a layer of glass beads). While the steady state critical taper is controlled by internal and basal friction coefficients and therefore the same in all experiments, different processes can minimise work by 1. reducing gravitational work e.g. by lowering the amount of uplift or volume uplifted, or 2. reducing frictional work e.g. by lowering the load or due to low friction coefficient along thrusts. Since a thick detachment allows entrainment of low friction material and therefore lowering of the friction along active thrusts, we speculate that the style of wedge growth will differ between the two models. We observe that the wedge with a thin basal detachment localizes strain at the toe of the wedge periodically and reactivate older faults to reach the critical topography. On the contrary, in the wedge with the thicker detachment layer, friction along thrusts is lowered due to the entrainment of low friction material from the detachment zone, subsequently increasing the lifetime of a thrust. Long thrust episodes are always followed by a fault of shorter lifetime, with the aim of reaching the critical taper. From the two experiments, we analyze the time-series evolution of the wedge to infer the work done by the two styles of deformation and predict the trend over time to differ but the maximum work to be similar Our observations show that the critical taper theory determines the geometry of the wedge in particular the taper angle. However the path and style of deformation that the wedge adopts i.e. strain partitioning or deformation along one fault, is determined by the energetically lowest pathway. The observation is especially evident in wedges with added complexities or random changes as the wedge matures. This study combines two theories to explain variability in the results of analogue models and perhaps may aid in understanding the complexity in natural wedges. It also delineates that two different mechanics of deformation can lead to the same geometrical wedge or final topography.

Effective star tracking method based on optical flow analysis for star trackers.

PubMed

Sun, Ting; Xing, Fei; Wang, Xiaochu; Li, Jin; Wei, Minsong; You, Zheng

2016-12-20

Benefiting from rapid development of imaging sensor technology, modern optical technology, and a high-speed computing chip, the star tracker's accuracy, dynamic performance, and update rate have been greatly improved with low power consumption and miniature size. The star tracker is currently one of the most competitive attitude measurement sensors. However, due to restrictions of the optical imaging system, difficulties still exist in moving star spot detection and star tracking when in special motion conditions. An effective star tracking method based on optical flow analysis for star trackers is proposed in this paper. Spot-based optical flow, based on a gray gradient between two adjacent star images, is analyzed to distinguish the star spot region and obtain an accurate star spot position so that the star tracking can keep continuous under high dynamic conditions. The obtained star vectors and extended Kalman filter (EKF) are then combined to conduct an angular velocity estimation to ensure region prediction of the star spot; this can be combined with the optical flow analysis result. Experiment results show that the method proposed in this paper has advantages in conditions of large angular velocity and large angular acceleration, despite the presence of noise. Higher functional density and better performance can be achieved; thus, the star tracker can be more widely applied in small satellites, remote sensing, and other complex space missions.

14 CFR 25.934 - Turbojet engine thrust reverser system tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbojet engine thrust reverser system... TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES Powerplant General § 25.934 Turbojet engine thrust reverser system tests. Thrust reversers installed on turbojet engines must meet the...

Thrust reverser analysis for implementation in the Aviation Environmental Design Tool (AEDT)

DOT National Transportation Integrated Search

2007-06-01

This letter report presents an updated implementation for thrust reversers in AEDT. Currently, thrust reverser is applied to all STANDARD approach profiles in the Integrated Noise Mode (lNM) as 60% of the max rated thrust for jets and 40% for props o...

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.

The Potential for Ambient Plasma Wave Propulsion

NASA Technical Reports Server (NTRS)

Gilland, James H.; Williams, George J.

2016-01-01

A truly robust space exploration program will need to make use of in-situ resources as much as possible to make the endeavor affordable. Most space propulsion concepts are saddled with one fundamental burden; the propellant needed to produce momentum. The most advanced propulsion systems currently in use utilize electric and/or magnetic fields to accelerate ionized propellant. However, significant planetary exploration missions in the coming decades, such as the now canceled Jupiter Icy Moons Orbiter, are restricted by propellant mass and propulsion system lifetimes, using even the most optimistic projections of performance. These electric propulsion vehicles are inherently limited in flexibility at their final destination, due to propulsion system wear, propellant requirements, and the relatively low acceleration of the vehicle. A few concepts are able to utilize the environment around them to produce thrust: Solar or magnetic sails and, with certain restrictions, electrodynamic tethers. These concepts focus primarily on using the solar wind or ambient magnetic fields to generate thrust. Technically immature, quasi-propellantless alternatives lack either the sensitivity or the power to provide significant maneuvering. An additional resource to be considered is the ambient plasma and magnetic fields in solar and planetary magnetospheres. These environments, such as those around the Sun or Jupiter, have been shown to host a variety of plasma waves. Plasma wave propulsion takes advantage of an observed astrophysical and terrestrial phenomenon: Alfven waves. These are waves that propagate in the plasma and magnetic fields around and between planets and stars. The generation of Alfven waves in ambient magnetic and plasma fields to generate thrust is proposed as a truly propellantless propulsion system which may enable an entirely new matrix of exploration missions. Alfven waves are well known, transverse electromagnetic waves that propagate in magnetized plasmas at frequencies below the ion cyclotron frequency. They have been observed in both laboratory and astrophysical settings. On Earth, they are being investigated as a possible means for plasma heating, current drive, and momentum addition in magnetic confinement fusion systems. In addition, Alfven waves have been proposed as a mechanism for acceleration of the solar wind away from the sun.

Low thrust chemical rocket technology

NASA Technical Reports Server (NTRS)

Schneider, Steven J.

1992-01-01

An on-going technology program to improve the performance of low thrust chemical rockets for spacecraft on-board propulsion applications is reviewed. Improved performance and lifetime is sought by the development of new predictive tools to understand the combustion and flow physics, introduction of high temperature materials and improved component designs to optimize performance, and use of higher performance propellants. Improved predictive technology is sought through the comparison of both local and global predictions with experimental data. Predictions are based on both the RPLUS Navier-Stokes code with finite rate kinetics and the JANNAF methodology. Data were obtained with laser-based diagnostics along with global performance measurements. Results indicate that the modeling of the injector and the combustion process needs improvement in these codes and flow visualization with a technique such as 2-D laser induced fluorescence (LIF) would aid in resolving issues of flow symmetry and shear layer combustion processes. High temperature material fabrication processes are under development and small rockets are being designed, fabricated, and tested using these new materials. Rhenium coated with iridium for oxidation protection was produced by the Chemical Vapor Deposition (CVD) process and enabled an 800 K increase in rocket operating temperature. Performance gains with this material in rockets using Earth storable propellants (nitrogen tetroxide and monomethylhydrazine or hydrazine) were obtained through component redesign to eliminate fuel film cooling and its associated combustion inefficiency while managing head end thermal soakback. Material interdiffusion and oxidation characteristics indicated that the requisite lifetimes of tens of hours were available for thruster applications. Rockets were designed, fabricated, and tested with thrusts of 22, 62, 440 and 550 N. Performance improvements of 10 to 20 seconds specific impulse were demonstrated. Higher performance propellants were evaluated: Space storable propellants, including liquid oxygen (LOX) as the oxidizer with nitrogen hydrides or hydrocarbon as fuels. Specifically, a LOX/hydrazine engine was designed, fabricated, and shown to have a 95 pct theoretical c-star which translates into a projected vacuum specific impulse of 345 seconds at an area ratio of 204:1. Further performance improvment can be obtained by the use of LOX/hydrogen propellants, especially for manned spacecraft applications, and specific designs must be developed and advanced through flight qualification.

Experimental results for a two-dimensional supersonic inlet used as a thrust deflecting nozzle

NASA Technical Reports Server (NTRS)

Johns, Albert L.; Burstadt, Paul L.

1984-01-01

Nearly all supersonic V/STOL aircraft concepts are dependent on the thrust deflecting capability of a nozzle. In one unique concept, referred to as the reverse flow dual fan, not only is there a thrust deflecting nozzle for the fan and core engine exit flow, but because of the way the propulsion system operates during vertical takeoff and landing, the supersonic inlet is also used as a thrust deflecting nozzle. This paper presents results of an experimental study to evaluate the performance of a supersonic inlet used as a thrust deflecting nozzle for this reverse flow dual fan concept. Results are presented in terms of nozzle thrust coefficient and thrust vector angle for a number of inlet/nozzle configurations. Flow visualization and nozzle exit flow survey results are also shown.

A 2dF survey of the Small Magellanic Cloud

NASA Astrophysics Data System (ADS)

Evans, Christopher J.; Howarth, Ian D.; Irwin, Michael J.; Burnley, Adam W.; Harries, Timothy J.

2004-09-01

We present a catalogue of new spectral types for hot, luminous stars in the Small Magellanic Cloud (SMC). The catalogue contains 4161 objects, giving an order-of-magnitude increase in the number of SMC stars with published spectroscopic classifications. The targets are primarily B- and A-type stars (2862 and 853 objects respectively), with one Wolf-Rayet, 139 O-type and 306 FG stars, sampling the main sequence to ~mid-B. The selection and classification criteria are described, and objects of particular interest are discussed, including UV-selected targets from the Ultraviolet Imaging Telescope (UIT) experiment, Be and B[e] stars, `anomalous A supergiants' and composite-spectrum systems. We examine the incidence of Balmer-line emission, and the relationship between Hγ equivalent width and absolute magnitude for BA stars.

Structural evidence for northeastward movement on the Chocolate Mountains thrust, southeasternmost Calfornia

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

Dillon, J.T.; Haxel, G.B.; Tosdal, R.M.

1990-11-10

The Late Cretaceous Chocolate Mountains thrust of southeastern California and southwestern Arizona places a block of Proterozoic and Mesozoic continental crust over the late Mesozoic continental margin oceanic sedimentary and volcanic rocks of the regionally distinctive Orocopia Schist. The Chocolate Mountains thrust is interpreted as a thrust (burial, subduction) fault rather than a low-angle normal (exhumation, unroofing, uplift) fault. The Chocolate Mountains thrust zone contains sparse to locally abundant mesoscopic asymmetric folds. Fabric relations indicate that these folds are an integral part of and coeval with the thrust zone. On a lower hemisphere equal-area plot representing the orientation and sensemore » of asymmetry of 80 thrust zone folds from 36 localities, spread over an area 60 by 10 km, Z folds plot northwest of and S folds plot southeast of a northeast-southwest striking vertical plane of overall monoclinic symmetry. The only sense of movement consistent with the collective asymmetry of the thrust zone folds is top to the northeast. Paleomagnetic data suggest that the original sense of thrusting, prior to Neogene vertical axis tectonic rotation related to the San Andreas fault system, was northward. The essential point is that movement of the upper plate of the Chocolate Mountains thrust evidently was continentward. Continentward thrusting suggests a tectonic scenario in which an insular or peninsular microcontinental fragment collided with mainland southern California. Alternative tectonic models involving subduction of the Orocopia Schist eastward beneath continental southern California circumvent the suture problem but are presently not supported by any direct structural evidence.« less

Multistory duplexes with forward dipping roofs, north central Brooks Range, Alaska

USGS Publications Warehouse

Wallace, W.K.; Moore, Thomas E.; Plafker, G.

1997-01-01

The Endicott Mountains allochthon has been thrust far northward over the North Slope parautochthon in the northern Brooks Range. Progressively younger units are exposed northward within the allochthon. To the south, the incompetent Hunt Fork Shale has thickened internally by asymmetric folds and thrust faults. Northward, the competent Kanayut Conglomerate forms a duplex between a floor thrust in Hunt Fork and a roof thrust in the Kayak Shale. To the north, the competent Lisburne Group forms a duplex between a floor thrust in Kayak and a roof thrust in the Siksikpuk Formation. Both duplexes formed from north vergent detachment folds whose steep limbs were later truncated by south dipping thrust faults that only locally breach immediately overlying roof thrusts. Within the parautochthon, the Kayak, Lisburne, and Siksikpuk-equivalent Echooka Formation form a duplex identical to that in the allochthon. This duplex is succeeded abruptly northward by detachment folds in Lisburne. These folds are parasitic to an anticlinorium interpreted to reflect a fault-bend folded horse in North Slope "basement," with a roof thrust in Kayak and a floor thrust at depth. These structures constitute two northward tapered, internally deformed wedges that are juxtaposed at the base of the allochthon. Within each wedge, competent units have been shortened independently between detachments, located mainly in incompetent units. The basal detachment of each wedge cuts upsection forward (northward) to define a wedge geometry within which units dip regionally forward. These dips reflect forward decrease in internal structural thickening by forward vergent folds and hindward dipping thrust faults. Copyright 1997 by the American Geophysical Union.

Constraints on the tectonics of the Mule Mountains Thrust System, southeast California and southwest Arizona

NASA Astrophysics Data System (ADS)

Tosdal, Richard M.

1990-11-01

The Mule Mountains thrust system crops out discontinuously over a 100-km-strike length in the Blythe-Quartzsite region of southeast California and southwest Arizona. Along the thrust system, middle and upper crustal metamorphic and plutonic rocks of Proterozoic and Mesozoic age are thrust north-northeastward (015° to 035°) over a lower plate metamorphic terrane that formed part of the Proterozoic North American craton, its Paleozoic sedimentary rock cover, overlying Mesozoic volcanic and sedimentary rocks, and the intruding Jurassic and Cretaceous granitic rocks. Stratigraphic, petrologic, and Pb isotopic ties for Jurassic granitoids and for Jurassic(?) and Cretaceous sedimentary rocks across the various parts of the thrust system indicate that related crustal blocks are superposed and preclude it from having large displacements. The thick-skinned thrust system is structurally symmetrical along its length with a central domain of synmetamorphic thrust faults that are flanked by western and eastern domains where lower plate synclines underlie the thrusts. Deformation occurred under low greenschist facies metamorphic conditions in the upper crust. Movement along the thrust system was probably limited to no more than a few tens of kilometers and occurred between 79±2 Ma and 70±4 Ma. The superposition of related rocks and the geometry of the thrust system preclude it from being a major tectonic boundary of post-Middle Jurassic age, as has been previously proposed. Rather, the thrust system forms the southern boundary of the narrow zone of Cretaceous intracratonic deformation, and it is one of the last tectonic events in the zone prior to regional cooling.

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

Star centroiding error compensation for intensified star sensors.

PubMed

Jiang, Jie; Xiong, Kun; Yu, Wenbo; Yan, Jinyun; Zhang, Guangjun

2016-12-26

A star sensor provides high-precision attitude information by capturing a stellar image; however, the traditional star sensor has poor dynamic performance, which is attributed to its low sensitivity. Regarding the intensified star sensor, the image intensifier is utilized to improve the sensitivity, thereby further improving the dynamic performance of the star sensor. However, the introduction of image intensifier results in star centroiding accuracy decrease, further influencing the attitude measurement precision of the star sensor. A star centroiding error compensation method for intensified star sensors is proposed in this paper to reduce the influences. First, the imaging model of the intensified detector, which includes the deformation parameter of the optical fiber panel, is established based on the orthographic projection through the analysis of errors introduced by the image intensifier. Thereafter, the position errors at the target points based on the model are obtained by using the Levenberg-Marquardt (LM) optimization method. Last, the nearest trigonometric interpolation method is presented to compensate for the arbitrary centroiding error of the image plane. Laboratory calibration result and night sky experiment result show that the compensation method effectively eliminates the error introduced by the image intensifier, thus remarkably improving the precision of the intensified star sensors.

Analysis of surface structures of chemically peculiar stars with modern and future interferometers

NASA Astrophysics Data System (ADS)

Shulyak, D.; Perraut, K.; Paladini, Claudia; Li Causi, G.; Sacuto, Stephane; Kochukhov, O.

2014-07-01

Interferometry is a very powerful observational technique known in astronomy for many decades. Its application to main-sequence stars, however, is still limited to only brightest objects. In this work we aim to explore the application of interferometry to a special class of main-sequence stars known as chemically peculiar (CP) stars. These stars demonstrate surface chemical abundance inhomogeneities (spots) that usually cover a considerable part of the stellar surface and induce a pronounced spectral and photometric variability. Interferometry thus has a potential to naturally resolve such spots in single stars, providing unique complementary information about spots sizes and contrasts. By means of numerical experiments we derive the actual interferometric requirements essential for the CP stars research that can be addressed in future instrument development. The first comparison between theoretical predictions and already available observations will also be discussed.

Possible evidence that pulsars are quark stars

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

Xu Renxin

2008-01-10

It is a pity that the real state of matter in pulsar-like stars is still not determined confidently because of the uncertainty about cold matter at supranuclear density, even 40 years after the discovery of pulsar. Nuclear matter (related to neutron stars) is one of the speculations for the inner constitution of pulsars even from the Landau's time more than 70 years ago, but quark matter (related to quark stars) is an alternative due to the fact of asymptotic freedom of interaction between quarks as the standard model of particle physics develops since 1960s. Therefore, one has to focus onmore » astrophysical observations in order to answer what the nature of pulsars is. In this presentation, I would like to summarize possible observational evidence/hints that pulsar-like stars could be quark stars, and to address achievable clear evidence for quark stars in the future experiments.« less

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Automatic takeoff thrust control system... Automatic takeoff thrust control system (ATTCS). Each applicant seeking approval for installation of an engine power control system that automatically resets the power or thrust on the operating engine(s) when...

14 CFR 25.904 - Automatic takeoff thrust control system (ATTCS).

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Automatic takeoff thrust control system... Automatic takeoff thrust control system (ATTCS). Each applicant seeking approval for installation of an engine power control system that automatically resets the power or thrust on the operating engine(s) when...

Relativistic stellar stability: An empirical approach

NASA Technical Reports Server (NTRS)

Ni, W.

1972-01-01

The PPN formalism which encompasses the post-Newtonian limit of nearly every metric theory of gravity is used to analyze stellar stability. This analysis enables one to infer, for any given gravitation theory, the extent to which post-Newtonian effects induce instabilities in white dwarfs, in neutron stars, and in supermassive stars. It also reveals the extent to which our current empirical knowledge of post-Newtonian gravity (based on solar-system experiments) actually guarantees that relativistic instabilities exist. In particular, it shows that: (1) for conservative theories of gravity, current solar-system experiments guarantee that the critical adiabatic index, for the stability of stars against radial pulsations exceeds the Newtonian value of 4/3 and (2) for nonconservative theories, current experiments do not permit any firm conclusion about the sign of the critical adiabatic index, and (3) in the PPN approximation to every metric theory, the standard Schwarzschild criterion for convection is valid.

ϒ Production in Heavy-Ion Collisions from the STAR Experiment

NASA Astrophysics Data System (ADS)

Ye, Zaochen; STAR Collaboration

2017-08-01

In these proceedings, we present recent results of ϒ measurements in heavy-ion collisions from the STAR experiment at RHIC. Nuclear modification factors (RAA) for ϒ (1 S) and ϒ (1 S + 2 S + 3 S) in U+U collisions at √{sNN } = 193 GeV are measured through the di-electron channel and compared to those in Au+Au collisions at √{sNN } = 200 GeV and Pb+Pb collisions at √{sNN } = 2.76 TeV. The ratio between the ϒ (2 S + 3 S) and ϒ (1 S) yields in Au+Au collisions at √{sNN } = 200 GeV is measured in the di-muon channel and compared to those in p+p collisions and in Pb+Pb collisions at √{sNN } = 2.76 TeV. Prospects for future ϒ measurements with the STAR experiment are also discussed.

Experimental, Theoretical, and Computational Investigation of Separated Nozzle Flows

NASA Technical Reports Server (NTRS)

Hunter, Craig A.

2004-01-01

A detailed experimental, theoretical, and computational study of separated nozzle flows has been conducted. Experimental testing was performed at the NASA Langley 16-Foot Transonic Tunnel Complex. As part of a comprehensive static performance investigation, force, moment, and pressure measurements were made and schlieren flow visualization was obtained for a sub-scale, non-axisymmetric, two-dimensional, convergent- divergent nozzle. In addition, two-dimensional numerical simulations were run using the computational fluid dynamics code PAB3D with two-equation turbulence closure and algebraic Reynolds stress modeling. For reference, experimental and computational results were compared with theoretical predictions based on one-dimensional gas dynamics and an approximate integral momentum boundary layer method. Experimental results from this study indicate that off-design overexpanded nozzle flow was dominated by shock induced boundary layer separation, which was divided into two distinct flow regimes; three- dimensional separation with partial reattachment, and fully detached two-dimensional separation. The test nozzle was observed to go through a marked transition in passing from one regime to the other. In all cases, separation provided a significant increase in static thrust efficiency compared to the ideal prediction. Results indicate that with controlled separation, the entire overexpanded range of nozzle performance would be within 10% of the peak thrust efficiency. By offering savings in weight and complexity over a conventional mechanical exhaust system, this may allow a fixed geometry nozzle to cover an entire flight envelope. The computational simulation was in excellent agreement with experimental data over most of the test range, and did a good job of modeling internal flow and thrust performance. An exception occurred at low nozzle pressure ratios, where the two-dimensional computational model was inconsistent with the three-dimensional separation observed in the experiment. In general, the computation captured the physics of the shock boundary layer interaction and shock induced boundary layer separation in the nozzle, though there were some differences in shock structure compared to experiment. Though minor, these differences could be important for studies involving flow control or thrust vectoring of separated nozzles. Combined with other observations, this indicates that more detailed, three-dimensional computational modeling needs to be conducted to more realistically simulate shock-separated nozzle flows.

Construction of the Database for Pulsating Variable Stars

NASA Astrophysics Data System (ADS)

Chen, Bing-Qiu; Yang, Ming; Jiang, Bi-Wei

2012-01-01

A database for pulsating variable stars is constructed to favor the study of variable stars in China. The database includes about 230,000 variable stars in the Galactic bulge, LMC and SMC observed in an about 10 yr period by the MACHO(MAssive Compact Halo Objects) and OGLE(Optical Gravitational Lensing Experiment) projects. The software used for the construction is LAMP, i.e., Linux+Apache+MySQL+PHP. A web page is provided for searching the photometric data and light curves in the database through the right ascension and declination of an object. Because of the flexibility of this database, more up-to-date data of variable stars can be incorporated into the database conveniently.

NASA Alternative Aviation Fuel Research

NASA Astrophysics Data System (ADS)

Anderson, B. E.; Beyersdorf, A. J.; Thornhill, K. L., II; Moore, R.; Shook, M.; Winstead, E.; Ziemba, L. D.; Crumeyrolle, S.

2015-12-01

We present an overview of research conducted by NASA Aeronautics Research Mission Directorate to evaluate the performance and emissions of "drop-in" alternative jet fuels, highlighting experiment design and results from the Alternative Aviation Fuel Experiments (AAFEX-I & -II) and Alternative Fuel-Effects on Contrails and Cruise Emissions flight series (ACCESS-I & II). These projects included almost 100 hours of sampling exhaust emissions from the NASA DC-8 aircraft in both ground and airborne operation and at idle to takeoff thrust settings. Tested fuels included Fischer-Tropsch (FT) synthetic kerosenes manufactured from coal and natural-gas feedstocks; Hydro-treated Esters and Fatty-Acids (HEFA) fuels made from beef-tallow and camelina-plant oil; and 50:50 blends of these alternative fuels with Jet A. Experiments were also conducted with FT and Jet A fuels doped with tetrahydrothiophene to examine the effects of fuel sulfur on volatile aerosol and contrail formation and microphysical properties. Results indicate that although the absence of aromatic compounds in the alternative fuels caused DC-8 fuel-system leaks, the fuels did not compromise engine performance or combustion efficiency. And whereas the alternative fuels produced only slightly different gas-phase emissions, dramatic reductions in non-volatile particulate matter (nvPM) emissions were observed when burning the pure alternative fuels, particularly at low thrust settings where particle number and mass emissions were an order of magnitude lower than measured from standard jet fuel combustion; 50:50 blends of Jet A and alternative fuels typically reduced nvPM emissions by ~50% across all thrust settings. Alternative fuels with the highest hydrogen content produced the greatest nvPM reductions. For Jet A and fuel blends, nvPM emissions were positively correlated with fuel aromatic and naphthalene content. Fuel sulfur content regulated nucleation mode aerosol number and mass concentrations within aging exhaust plumes, but did not clearly impact contrail formation or microphysics.

Parametric study of the swimming performance of a fish robot propelled by a flexible caudal fin.

PubMed

Low, K H; Chong, C W

2010-12-01

In this paper, we aim to study the swimming performance of fish robots by using a statistical approach. A fish robot employing a carangiform swimming mode had been used as an experimental platform for the performance study. The experiments conducted aim to investigate the effect of various design parameters on the thrust capability of the fish robot with a flexible caudal fin. The controllable parameters associated with the fin include frequency, amplitude of oscillation, aspect ratio and the rigidity of the caudal fin. The significance of these parameters was determined in the first set of experiments by using a statistical approach. A more detailed parametric experimental study was then conducted with only those significant parameters. As a result, the parametric study could be completed with a reduced number of experiments and time spent. With the obtained experimental result, we were able to understand the relationship between various parameters and a possible adjustment of parameters to obtain a higher thrust. The proposed statistical method for experimentation provides an objective and thorough analysis of the effects of individual or combinations of parameters on the swimming performance. Such an efficient experimental design helps to optimize the process and determine factors that influence variability.

User Centric Job Monitoring - a redesign and novel approach in the STAR experiment

NASA Astrophysics Data System (ADS)

Arkhipkin, D.; Lauret, J.; Zulkarneeva, Y.

2014-06-01

User Centric Monitoring (or UCM) has been a long awaited feature in STAR, whereas programs, workflows and system "events" could be logged, broadcast and later analyzed. UCM allows to collect and filter available job monitoring information from various resources and present it to users in a user-centric view rather than an administrative-centric point of view. The first attempt and implementation of "a" UCM approach was made in STAR 2004 using a log4cxx plug-in back-end and then further evolved with an attempt to push toward a scalable database back-end (2006) and finally using a Web-Service approach (2010, CSW4DB SBIR). The latest showed to be incomplete and not addressing the evolving needs of the experiment where streamlined messages for online (data acquisition) purposes as well as the continuous support for the data mining needs and event analysis need to coexists and unified in a seamless approach. The code also revealed to be hardly maintainable. This paper presents the next evolutionary step of the UCM toolkit, a redesign and redirection of our latest attempt acknowledging and integrating recent technologies and a simpler, maintainable and yet scalable manner. The extended version of the job logging package is built upon three-tier approach based on Task, Job and Event, and features a Web-Service based logging API, a responsive AJAX-powered user interface, and a database back-end relying on MongoDB, which is uniquely suited for STAR needs. In addition, we present details of integration of this logging package with the STAR offline and online software frameworks. Leveraging on the reported experience and work from the ATLAS and CMS experience on using the ESPER engine, we discuss and show how such approach has been implemented in STAR for meta-data event triggering stream processing and filtering. An ESPER based solution seems to fit well into the online data acquisition system where many systems are monitored.

Conceptual Design of a Tiltrotor Transport Flight Deck

NASA Technical Reports Server (NTRS)

Decker, William A.; Dugan, Daniel C.; Simmons, Rickey C.; Tucker, George E.; Aiken, Edwin W. (Technical Monitor)

1995-01-01

A tiltrotor transport has considerable potential as a regional transport, increasing the air transportation system capacity by off-loading conventional runways. Such an aircraft will have a flight deck suited to its air transportation task and adapted to unique urban vertiport operating requirements. Such operations are likely to involve steep, slow instrument approaches for vertical and extremely short rolling take-offs and landings. While much of a tiltrotor transport's operations will be in common with commercial fixed-wing operations, terminal area operations will impose alternative flight deck design solutions. Control systems, displays and guidance, and control inceptors must be tailored to both routine and emergency vertical flight operations. This paper will survey recent experience with flight deck design elements suitable to a tiltrotor transport and will propose a conceptual cockpit design for such an aircraft. A series of piloted simulations using the NASA Ames Vertical Motion Simulator have investigated cockpit design elements and operating requirements for tiltrotor transports operating into urban vertiports. These experiments have identified the need for a flight director or equivalent display guidance for steep final approaches. A flight path vector display format has proven successful for guiding tiltrotor transport terminal area operations. Experience with a Head-Up Display points to the need for a bottom-mounted display device to maximize its utility on steep final approach paths. Configuration control (flap setting and nacelle angle) requires appropriate augmentation and tailoring for civil transport operations, flown to an airline transport pilot instrument flight rules (ATP-IFR) standard. The simulation experiments also identified one thrust control lever geometry as inappropriate to the task and found at least acceptable results with the vertical thrust control lever of the XV-15. In addition to the thrust controller, the attitude control of a tiltrotor transport may be effected through an inceptor other than the current center sticks in the XV-15 and V-22. Simulation and flight investigations of side-stick control inceptors for rotorcraft, augmented by a 1985 flight test of a side-stick controller in the XV-15 suggest the potential of such a device in a transport cockpit.

Supersonic wings with significant leading-edge thrust at cruise

NASA Technical Reports Server (NTRS)

Robins, A. W.; Carlson, H. W.; Mack, R. J.

1980-01-01

Experimental/theoretical correlations are presented which show that significant levels of leading-edge thrust are possible at supersonic speeds for certain planforms having the geometry to support the theoretical thrust-distribution potential. The new analytical process employed provides not only the level of leading-edge thrust attainable but also the spanwise distribution of both it and that component of full theoretical thrust which acts as vortex lift. Significantly improved aerodynamic performance in the moderate supersonic speed regime is indicated.

Thrust modeling for hypersonic engines

NASA Technical Reports Server (NTRS)

Riggins, D. W.; Mcclinton, C. R.

1995-01-01

Expressions for the thrust losses of a scramjet engine are developed in terms of irreversible entropy increases and the degree of incomplete combustion. A method is developed which allows the calculation of the lost vehicle thrust due to different loss mechanisms within a given flow-field. This analysis demonstrates clearly the trade-off between mixing enhancement and resultant increased flow losses in scramjet combustors. An engine effectiveness parameter is defined in terms of thrust loss. Exergy and the thrust-potential method are related and compared.

Some tests on small-scale rectangular throat ejector. [thrust augmentation for V/STOL aircraft

NASA Technical Reports Server (NTRS)

Dean, W. N., Jr.; Franke, M. E.

1979-01-01

A small scale rectangular throat ejector with plane slot nozzles and a fixed throat area was tested to determine the effects of diffuser sidewall length, diffuser area ratio, and sidewall nozzle position on thrust and mass augmentation. The thrust augmentation ratio varied from approximately 0.9 to 1.1. Although the ejector did not have good thrust augmentation performance, the effects of the parameters studied are believed to indicate probable trends in thrust augmenting ejectors.

Ultraviolet photometry from the orbiting astronomical observatory. 8: The blue Ap stars

NASA Technical Reports Server (NTRS)

Leckrone, D. S.

1973-01-01

The filter photometers in the Wisconsin Experiment Package on OAO-2 were used to obtain data for a carefully selected set of 24 blue Ap stars and 31 comparison standard B and A dwarfs and giants for a program of relative photometry. Observations were made in seven bandpasses over the effective wavelength range 1430A-4250A. The Ap stars observed include members of the Si, Hg-Mn and Sr-Cr-Eu peculiarity classes. Most of them are too blue in B-V for their published MK spectral classes. The blue Ap stars are markedly deficient in emitted ultraviolet flux and are underluminous as compared to normal stars with the same UBV colors. The Hg-Mn stars appear less flux deficient in the ultraviolet for their UBV colors than do Si or Sr-cr-Eu stars. Most of the Ap stars observed possess ultraviolet flux distributions, or ultraviolet color temperatures, consistent with their published MK spectral classes to well within the classification uncertainties.

NASA Rocket Experiment Finds the Universe Brighter Than We Thought

NASA Image and Video Library

2017-12-08

A NASA sounding rocket experiment has detected a surprising surplus of infrared light in the dark space between galaxies, a diffuse cosmic glow as bright as all known galaxies combined. The glow is thought to be from orphaned stars flung out of galaxies. The findings redefine what scientists think of as galaxies. Galaxies may not have a set boundary of stars, but instead stretch out to great distances, forming a vast, interconnected sea of stars. Observations from the Cosmic Infrared Background Experiment, or CIBER, are helping settle a debate on whether this background infrared light in the universe, previously detected by NASA’s Spitzer Space Telescope, comes from these streams of stripped stars too distant to be seen individually, or alternatively from the first galaxies to form in the universe. This is a time-lapse photograph of the Cosmic Infrared Background Experiment (CIBER) rocket launch, taken from NASA's Wallops Flight Facility in Virginia in 2013. The image is from the last of four launches. Read more: www.nasa.gov/press/2014/november/nasa-rocket-experiment-f... Image Credit: T. Arai/University of Tokyo NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

My Lived Experiences Are More Important Than Your Probabilities: The Role of Individualized Risk Estimates for Decision Making about Participation in the Study of Tamoxifen and Raloxifene (STAR).

PubMed

Holmberg, Christine; Waters, Erika A; Whitehouse, Katie; Daly, Mary; McCaskill-Stevens, Worta

2015-11-01

Decision-making experts emphasize that understanding and using probabilistic information are important for making informed decisions about medical treatments involving complex risk-benefit tradeoffs. Yet empirical research demonstrates that individuals may not use probabilities when making decisions. To explore decision making and the use of probabilities for decision making from the perspective of women who were risk-eligible to enroll in the Study of Tamoxifen and Raloxifene (STAR). We conducted narrative interviews with 20 women who agreed to participate in STAR and 20 women who declined. The project was based on a narrative approach. Analysis included the development of summaries of each narrative, and thematic analysis with developing a coding scheme inductively to code all transcripts to identify emerging themes. Interviewees explained and embedded their STAR decisions within experiences encountered throughout their lives. Such lived experiences included but were not limited to breast cancer family history, a personal history of breast biopsies, and experiences or assumptions about taking tamoxifen or medicines more generally. Women's explanations of their decisions about participating in a breast cancer chemoprevention trial were more complex than decision strategies that rely solely on a quantitative risk-benefit analysis of probabilities derived from populations In addition to precise risk information, clinicians and risk communicators should recognize the importance and legitimacy of lived experience in individual decision making. © The Author(s) 2015.

Design and analysis report for the RL10-2B breadboard low thrust engine

NASA Technical Reports Server (NTRS)

Brown, J. R.; Foust, R. R.; Galler, D. E.; Kanic, P. G.; Kmiec, T. D.; Limerick, C. D.; Peckham, R. J.; Swartwout, T.

1984-01-01

The breadboard low thrust RL10-2B engine is described. A summary of the analysis and design effort to define the multimode thrust concept applicable to the requirements for the upper stage vehicles is provided. Baseline requirements were established for operation of the RL10-2B engine under the following conditions: (1) tank head idle at low propellant tank pressures without vehicle propellant conditioning or settling thrust; (2) pumped idle at a ten percent thrust level for low G deployment and/or vehicle tank pressurization; and (3) full thrust (15,000 lb.). Several variations of the engine configuration were investigated and results of the analyses are included.

Evaluation of a simplified gross thrust calculation method for a J85-21 afterburning turbojet engine in an altitude facility

NASA Technical Reports Server (NTRS)

Baer-Riedhart, J. L.

1982-01-01

A simplified gross thrust calculation method was evaluated on its ability to predict the gross thrust of a modified J85-21 engine. The method used tailpipe pressure data and ambient pressure data to predict the gross thrust. The method's algorithm is based on a one-dimensional analysis of the flow in the afterburner and nozzle. The test results showed that the method was notably accurate over the engine operating envelope using the altitude facility measured thrust for comparison. A summary of these results, the simplified gross thrust method and requirements, and the test techniques used are discussed in this paper.

Preliminary characterization of a laser-generated plasma sheet

DOE PAGES

Keiter, P. A.; Malamud, G.; Trantham, M.; ...

2014-12-10

We present the results from recent experiments to create a flowing plasma sheet. Two groups of three laser beams with nominally 1.5 kJ of energy per group were focused to separate pointing locations, driving a shock into a wedge target. As the shock breaks out of the wedge, the plasma is focused on center, creating a sheet of plasma. Measurements at 60 ns indicate the plasma sheet has propagated 2825 microns with an average velocity of 49 microns/ns. These experiments follow previous experiments, which are aimed at studying similar physics as that found in the hot spot region of cataclysmicmore » variables. Krauland et al created a flowing plasma, which represents the flowing plasma from the secondary star. This flow interacted with a stationary object, which represented the disk around the white dwarf. A reverse shock is a shock formed when a freely expanding plasma encounters an obstacle. Reverse shocks can be generated by a blast wave propagating through a medium. As a result, they can also be found in binary star systems where the flowing gas from a companion star interacts with the accretion disk of the primary star.« less

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.

Influence of the thrust bearing on the natural frequencies of a 72-MW hydropower rotor

NASA Astrophysics Data System (ADS)

Cupillard, S.; Aidanpää, J.-O.

2016-11-01

The thrust bearing is an essential element of a hydropower machine. Not only does it carry the total axial load but it also introduces stiffness and damping properties in the system. The focus of this study is on the influence of the thrust bearing on the lateral vibrations of the shaft of a 72-MW propeller turbine. The thrust bearing has a non-conventional design with a large radius and two rows of thrust pads. A numerical model is developed to estimate natural frequencies. Numerical results are analyzed and related to experimental measurements of a runaway test. The results show the need to include the thrust bearing in the model. In fact, the vibration modes are substantially increased towards higher frequencies with the added properties from the thrust bearing. The second mode of vibration has been identified in the experimental measurements. Its frequency and mode shape compare well with numerical results.

Thrust faults and related structures in the crater floor of Mount St. Helens volcano, Washington

USGS Publications Warehouse

Chadwick, W.W.; Swanson, D.A.

1989-01-01

A lava dome was built in the crater of Mount St. Helens by intermittent intrusion and extrusion of dacite lava between 1980 and 1986. Spectacular ground deformation was associated with the dome-building events and included the development of a system of radial cracks and tangential thrust faults in the surrounding crater floor. These cracks and thrusts, best developed and studied in 1981-1982, formed first and, as some evolved into strike-slip tear faults, influenced the subsequent geometry of thrusting. Once faulting began, deformation was localized near the thrust scarps and their bounding tear faults. The magnitude of displacements systematically increased before extrusions, whereas the azimuth and inclination of displacements remained relatively constant. The thrust-fault scarps were bulbous in profile, lobate in plan, and steepened during continued fault movement. The hanging walls of each thrust were increasingly disrupted as cumulative fault slip increased. -from Authors

Optimal high- and low-thrust geocentric transfer

NASA Technical Reports Server (NTRS)

Sackett, L. L.; Edelbaum, T. N.

1974-01-01

A computer code which rapidly calculates time optimal combined high- and low-thrust transfers between two geocentric orbits in the presence of a strong gravitational field has been developed as a mission analysis tool. The low-thrust portion of the transfer can be between any two arbitrary ellipses. There is an option for including the effect of two initial high-thrust impulses which would raise the spacecraft from a low, initially circular orbit to the initial orbit for the low-thrust portion of the transfer. In addition, the effect of a single final impulse after the low-thrust portion of the transfer may be included. The total Delta V for the initial two impulses must be specified as well as the Delta V for the final impulse. Either solar electric or nuclear electric propulsion can be assumed for the low-thrust phase of the transfer.

Computational Study of Fluidic Thrust Vectoring using Separation Control in a Nozzle

NASA Technical Reports Server (NTRS)

Deere, Karen; Berrier, Bobby L.; Flamm, Jeffrey D.; Johnson, Stuart K.

2003-01-01

A computational investigation of a two- dimensional nozzle was completed to assess the use of fluidic injection to manipulate flow separation and cause thrust vectoring of the primary jet thrust. The nozzle was designed with a recessed cavity to enhance the throat shifting method of fluidic thrust vectoring. The structured-grid, computational fluid dynamics code PAB3D was used to guide the design and analyze over 60 configurations. Nozzle design variables included cavity convergence angle, cavity length, fluidic injection angle, upstream minimum height, aft deck angle, and aft deck shape. All simulations were computed with a static freestream Mach number of 0.05. a nozzle pressure ratio of 3.858, and a fluidic injection flow rate equal to 6 percent of the primary flow rate. Results indicate that the recessed cavity enhances the throat shifting method of fluidic thrust vectoring and allows for greater thrust-vector angles without compromising thrust efficiency.

Low thrust vehicle concept study

NASA Technical Reports Server (NTRS)

1980-01-01

Low thrust chemical (hydrogen-oxygen) propulsion systems configured specifically for low acceleration orbit transfer of large space systems were defined. Results indicate that it is cost effective and least risk to combine the OTV and stowed spacecraft in a single 65 K Shuttle. The study shows that the engine for an optimized low thrust stage (1) does not require very low thrust; (2) 1-3 K thrust range appears optimum; (3) thrust transient is not a concern; (4) throttling probably not worthwhile; and (5) multiple thrusters complicate OTV/LSS design and aggravate LSS loads. Regarding the optimum vehicle for low acceleration missions, the single shuttle launch (LSS and expendable OTV) is most cost effective and least risky. Multiple shuttles increase diameter 20%. The space based radar structure short OTV (which maximizes space available for packaged LSS) favors use of torus tank. Propellant tank pressures/vapor residuals are little affected by engine thrust level or number of burns.

Direct thrust measurements and modelling of a radio-frequency expanding plasma thruster

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

Lafleur, T.; Charles, C.; Boswell, R. W.

2011-08-15

It is shown analytically that the thrust from a simple plasma thruster (in the absence of a magnetic field) is given by the maximum upstream electron pressure, even if the plasma diverges downstream. Direct thrust measurements of a thruster are then performed using a pendulum thrust balance and a laser displacement sensor. A maximum thrust of about 2 mN is obtained at 700 W for a thruster length of 17.5 cm and a flow rate of 0.9 mg s{sup -1}, while a larger thrust of 4 mN is obtained at a similar power for a length of 9.5 cm andmore » a flow rate of 1.65 mg s{sup -1}. The measured thrusts are in good agreement with the maximum upstream electron pressure found from measurements of the plasma parameters and in fair agreement with a simple global approach used to model the thruster.« less

14 CFR 23.934 - Turbojet and turbofan engine thrust reverser systems tests.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Turbojet and turbofan engine thrust... CATEGORY AIRPLANES Powerplant General § 23.934 Turbojet and turbofan engine thrust reverser systems tests. Thrust reverser systems of turbojet or turbofan engines must meet the requirements of § 33.97 of this...

Thrust and Propulsive Efficiency from an Instructive Viewpoint

ERIC Educational Resources Information Center

Kaufman, Richard D.

2010-01-01

In a typical engineering or physics curriculum, the momentum equation is used for the determination of jet engine thrust. Even a simple thrust analysis requires a heavy emphasis on mathematics that can cause students and engineers to lose a physical perspective on thrust. This article provides for this physical understanding using only static…

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.

Large Eddy Simulation of Crashback in Marine Propulsors

NASA Astrophysics Data System (ADS)

Jang, Hyunchul

Crashback is an operating condition to quickly stop a propelled vehicle, where the propeller is rotated in the reverse direction to yield negative thrust. The crashback condition is dominated by the interaction of the free stream flow with the strong reverse flow. This interaction forms a highly unsteady vortex ring, which is a very prominent feature of crashback. Crashback causes highly unsteady loads and flow separation on the blade surface. The unsteady loads can cause propulsor blade damage, and also affect vehicle maneuverability. Crashback is therefore well known as one of the most challenging propeller states to analyze. This dissertation uses Large-Eddy Simulation (LES) to predict the highly unsteady flow field in crashback. A non-dissipative and robust finite volume method developed by Mahesh et al. (2004) for unstructured grids is applied to flow around marine propulsors. The LES equations are written in a rotating frame of reference. The objectives of this dissertation are: (1) to understand the flow physics of crashback in marine propulsors with and without a duct, (2) to develop a finite volume method for highly skewed meshes which usually occur in complex propulsor geometries, and (3) to develop a sliding interface method for simulations of rotor-stator propulsor on parallel platforms. LES is performed for an open propulsor in crashback and validated against experiments performed by Jessup et al. (2004). The LES results show good agreement with experiments. Effective pressures for thrust and side-force are introduced to more clearly understand the physical sources of thrust and side-force. Both thrust and side-force are seen to be mainly generated from the leading edge of the suction side of the propeller. This implies that thrust and side-force have the same source---the highly unsteady leading edge separation. Conditional averaging is performed to obtain quantitative information about the complex flow physics of high- or low-amplitude events. The events for thrust and side force show the same tendency. The conditional averages show that during high amplitude events, the vortex ring core is closer to the propeller blades, the reverse flow induced by the propeller rotation is lower, the forward flow is higher at the root of the blades, and leading and trailing edge flow separations are larger. The instantaneous flow field shows that during low amplitude events, the vortex ring is more axisymmetric and the stronger reverse flow induced by the vortex ring suppresses the forward flow so that flow separation on the blades is smaller. During high amplitude events, the vortex ring is less coherent and the weaker reverse flow cannot overcome the forward flow. The stronger forward flow makes flow separation on the blades larger. The effect of a duct on crashback is studied with LES. Thrust mostly arises from the blade surface, but most of side-force is generated from the duct surface. Both mean and RMS of pressure are much higher on inner surface of duct, especially near blade tips. This implies that side-force on the ducted propulsor is caused by the blade-duct interaction. Strong tip leakage flow is observed behind the suction side at the tip gap. The physical source of the tip leakage flow is seen to be the large pressure difference between pressure and suction sides. The conditional average for high amplitude event shows consistent results; the tip leakage flow and pressure difference are significantly higher when thrust and side-force are higher. A sliding interface method is developed to allow simulations of rotor-stator propulsor in crashback. The method allows relative rotations between different parts of the computational grid. Search algorithm for sliding elements, data structures for message passing, and accurate interpolation scheme at the sliding interface are developed for arbitrary shaped unstructured grids on parallel computing platforms. Preliminary simulations of open propulsor in crashback show reasonable performance.

Dynamic imaging model and parameter optimization for a star tracker.

PubMed

Yan, Jinyun; Jiang, Jie; Zhang, Guangjun

2016-03-21

Under dynamic conditions, star spots move across the image plane of a star tracker and form a smeared star image. This smearing effect increases errors in star position estimation and degrades attitude accuracy. First, an analytical energy distribution model of a smeared star spot is established based on a line segment spread function because the dynamic imaging process of a star tracker is equivalent to the static imaging process of linear light sources. The proposed model, which has a clear physical meaning, explicitly reflects the key parameters of the imaging process, including incident flux, exposure time, velocity of a star spot in an image plane, and Gaussian radius. Furthermore, an analytical expression of the centroiding error of the smeared star spot is derived using the proposed model. An accurate and comprehensive evaluation of centroiding accuracy is obtained based on the expression. Moreover, analytical solutions of the optimal parameters are derived to achieve the best performance in centroid estimation. Finally, we perform numerical simulations and a night sky experiment to validate the correctness of the dynamic imaging model, the centroiding error expression, and the optimal parameters.

Spectroscopic Analyses of the "Blue Hook" Stars in Omega Centauri: A Test of the Late Hot Flasher Scenario

NASA Technical Reports Server (NTRS)

Moehler, S.; Sweigart, Allan V.; Landsman, W. B.; Dreizler, S.; Rabin, Douglas M. (Technical Monitor)

2002-01-01

(Omega) Cen contains the largest population of very hot horizontal branch (HB) stars known in a globular cluster. Recent UV observations (Whitney et al. 1998; D'Cruz et al. 2000) show a significant population of hot stars below the zero-age horizontal branch ("blue hook" stars), which cannot be explained by canonical stellar evolution. Stars which suffer unusually large mass loss on the red giant branch and thus experience the helium core flash while descending the white dwarf cooling curve could populate this region. Theory predicts that these "late hot flashers" should show higher temperatures than the hottest canonical HB stars and should have helium- and carbon-rich atmospheres. We obtained and analysed medium resolution spectra of a sample of blue hook stars to derive their atmospheric parameters. The blue hook stars are indeed both hotter (T(sub eff)>35,000 K) and more helium-rich than classical extreme HB stars. In addition we find indications for a large enhancement of the carbon abundance relative to the cluster abundance.

Smearing model and restoration of star image under conditions of variable angular velocity and long exposure time.

PubMed

Sun, Ting; Xing, Fei; You, Zheng; Wang, Xiaochu; Li, Bin

2014-03-10

The star tracker is one of the most promising attitude measurement devices widely used in spacecraft for its high accuracy. High dynamic performance is becoming its major restriction, and requires immediate focus and promotion. A star image restoration approach based on the motion degradation model of variable angular velocity is proposed in this paper. This method can overcome the problem of energy dispersion and signal to noise ratio (SNR) decrease resulting from the smearing of the star spot, thus preventing failed extraction and decreased star centroid accuracy. Simulations and laboratory experiments are conducted to verify the proposed methods. The restoration results demonstrate that the described method can recover the star spot from a long motion trail to the shape of Gaussian distribution under the conditions of variable angular velocity and long exposure time. The energy of the star spot can be concentrated to ensure high SNR and high position accuracy. These features are crucial to the subsequent star extraction and the whole performance of the star tracker.

Analyzing structural variations along strike in a deep-water thrust belt

NASA Astrophysics Data System (ADS)

Totake, Yukitsugu; Butler, Robert W. H.; Bond, Clare E.; Aziz, Aznan

2018-03-01

We characterize a deep-water fold-thrust arrays imaged by a high-resolution 3D seismic dataset in the offshore NW Borneo, Malaysia, to understand the kinematics behind spatial arrangement of structural variations throughout the fold-thrust system. The seismic volume used covers two sub-parallel fold trains associated with a series of fore-thrusts and back-thrusts. We measured fault heave, shortening value, fold geometries (forelimb dip, interlimb angle and crest depth) along strike in individual fold trains. Heave plot on strike projection allows to identify individual thrust segments showing semi-elliptical to triangular to bimodal patterns, and linkages of these segments. The linkage sites are marked by local minima in cumulative heave. These local heave minima are compensated by additional structures, such as small imbricate thrusts and tight folds indicated by large forelimb dip and small interlimb angle. Complementary profiles of the shortening amount for the two fold trains result in smoother gradient of total shortening across the structures. We interpret this reflects kinematic interaction between two fold-thrust trains. This type of along-strike variation analysis provides comprehensive understanding of a fold-thrust system and may provide an interpretative strategy for inferring the presence of complex multiple faults in less well-imaged parts of seismic volumes.

Structure, burial history, and petroleum potential of frontal thrust belt and adjacent foreland, southwest Montana.

USGS Publications Warehouse

Perry, W.J.; Wardlaw, B.R.; Bostick, N.H.; Maughan, E.K.

1983-01-01

The frontal thrust belt in the Lima area of SW Montana consists of blind (nonsurfacing) thrusts of the Lima thrust system beneath the Lima anticline and the Tendoy thrust sheet to the W. The Tendoy sheet involves Mississippian through Cretaceous rocks of the SW-plunging nose of the Mesozoic Blacktail-Snowcrest uplift that are thrust higher (NE) onto the uplift. The front of the Tendoy sheet W of Lima locally has been warped by later compressive deformation which also involved synorogenic conglomerates of the structurally underlying Beaverhead Formation. To the N, recent extension faulting locally has dropped the front of the Tendoy sheet beneath Quaternary gravels. Rocks of the exposed Tendoy sheet have never been deeply buried, based on vitrinite relectance of = or <0.6%, conodont CAI (color alteration index) values that are uniformly 1, and on supporting organic geochemical data from Paleozoic rocks from the Tendoy thrust sheet. Directly above and W of the Tendoy sheet lie formerly more deeply buried rocks of the Medicine Lodge thrust system. Their greater burial depth is indicated by higher conodont CAI values. W-dipping post-Paleocene extension faults truncate much of the rear part of the Tendoy sheet and also separate the Medicine Lodge sheet from thrust sheets of the Beaverhead Range still farther W. -from Authors

Experimental Investigation of Unsteady Thrust Augmentation Using a Speaker-Driven Jet

NASA Technical Reports Server (NTRS)

Paxson, Daniel E.; Wernet, Mark P.; John, Wentworth T.

2007-01-01

An experimental investigation is described in which a simple speaker-driven jet was used as a pulsed thrust source (driver) for an ejector configuration. The objectives of the investigation were twofold. The first was to expand the experimental body of evidence showing that an unsteady thrust source, combined with a properly sized ejector generally yields higher thrust augmentation values than a similarly sized, steady driver of equivalent thrust. The second objective was to identify characteristics of the unsteady driver that may be useful for sizing ejectors, and for predicting the thrust augmentation levels that may be achieved. The speaker-driven jet provided a convenient source for the investigation because it is entirely unsteady (i.e., it has no mean velocity component) and because relevant parameters such as frequency, time-averaged thrust, and diameter are easily variable. The experimental setup will be described, as will the two main measurements techniques employed. These are thrust and digital particle imaging velocimetry of the driver. It will be shown that thrust augmentation values as high as 1.8 were obtained, that the diameter of the best ejector scaled with the dimensions of the emitted vortex, and that the so-called formation time serves as a useful dimensionless parameter by which to characterize the jet and predict performance.

Dynamic rupture modeling of thrust faults with parallel surface traces.

NASA Astrophysics Data System (ADS)

Peshette, P.; Lozos, J.; Yule, D.

2017-12-01

Fold and thrust belts (such as those found in the Himalaya or California Transverse Ranges) consist of many neighboring thrust faults in a variety of geometries. Active thrusts within these belts individually contribute to regional seismic hazard, but further investigation is needed regarding the possibility of multi-fault rupture in a single event. Past analyses of historic thrust surface traces suggest that rupture within a single event can jump up to 12 km. There is also observational precedent for long distance triggering between subparallel thrusts (e.g. the 1997 Harnai, Pakistan events, separated by 50 km). However, previous modeling studies find a maximum jumping rupture distance between thrust faults of merely 200 m. Here, we present a new dynamic rupture modeling parameter study that attempts to reconcile these differences and determine which geometrical and stress conditions promote jumping rupture. We use a community verified 3D finite element method to model rupture on pairs of thrust faults with parallel surface traces. We vary stress drop and fault strength to determine which conditions produce jumping rupture at different dip angles and different separations between surface traces. This parameter study may help to understand the likelihood of jumping rupture in real-world thrust systems, and may thereby improve earthquake hazard assessment.

Fuel-optimal low-thrust formation reconfiguration via Radau pseudospectral method

NASA Astrophysics Data System (ADS)

Li, Jing

2016-07-01

This paper investigates fuel-optimal low-thrust formation reconfiguration near circular orbit. Based on the Clohessy-Wiltshire equations, first-order necessary optimality conditions are derived from the Pontryagin's maximum principle. The fuel-optimal impulsive solution is utilized to divide the low-thrust trajectory into thrust and coast arcs. By introducing the switching times as optimization variables, the fuel-optimal low-thrust formation reconfiguration is posed as a nonlinear programming problem (NLP) via direct transcription using multiple-phase Radau pseudospectral method (RPM), which is then solved by a sparse nonlinear optimization software SNOPT. To facilitate optimality verification and, if necessary, further refinement of the optimized solution of the NLP, formulas for mass costate estimation and initial costates scaling are presented. Numerical examples are given to show the application of the proposed optimization method. To fix the problem, generic fuel-optimal low-thrust formation reconfiguration can be simplified as reconfiguration without any initial and terminal coast arcs, whose optimal solutions can be efficiently obtained from the multiple-phase RPM at the cost of a slight fuel increment. Finally, influence of the specific impulse and maximum thrust magnitude on the fuel-optimal low-thrust formation reconfiguration is analyzed. Numerical results shown the links and differences between the fuel-optimal impulsive and low-thrust solutions.

Progressive deformation and superposed fabrics related to Cretaceous crustal underthrusting in western Arizona, U.S.A.

USGS Publications Warehouse

Laubach, S.E.; Reynolds, S.J.; Spencer, J.E.; Marshak, S.

1989-01-01

In the Maria fold and thrust belt, a newly recognized E-trending Cretaceous orogenic belt in the southwestern United States, ductile thrusts, large folds and superposed cleavages record discordant emplacement of crystalline thrust sheets across previously tilted sections of crust. Style of deformation and direction of thrusting are in sharp contrast to those of the foreland fold-thrust belt in adjacent segments of the Cordillera. The net effect of polyphase deformation in the Maria belt was underthrusting of Paleozoic and Mesozoic metasedimentary rocks under the Proterozoic crystalline basement of North America. The structure of the Maria belt is illustrated by the Granite Wash Mountains in west-central Arizona, where at least four non-coaxial deformation events (D1-D4) occurred during the Cretaceous. SSE-facing D1 folds are associated with S-directed thrusts and a low-grade slaty cleavage. D1 structures are truncated by the gently-dipping Hercules thrust zone (D2), a regional SW-vergent shear zone that placed Proterozoic and Jurassic crystalline rocks over upturned Paleozoic and Mesozoic supracrustal rocks. Exposures across the footwall margin of the Hercules thrust zone show the progressive development of folds, cleavage and metamorphism related to thrusting. D3 and D4 structures include open folds and spaced cleavages that refold or transect D1 and D2 folds. The D2 Hercules thrust zone and a D3 shear zone are discordantly crosscut by late Cretaceous plutons. ?? 1989.

The dimensionality of stellar chemical space using spectra from the Apache Point Observatory Galactic Evolution Experiment

NASA Astrophysics Data System (ADS)

Price-Jones, Natalie; Bovy, Jo

2018-03-01

Chemical tagging of stars based on their similar compositions can offer new insights about the star formation and dynamical history of the Milky Way. We investigate the feasibility of identifying groups of stars in chemical space by forgoing the use of model derived abundances in favour of direct analysis of spectra. This facilitates the propagation of measurement uncertainties and does not pre-suppose knowledge of which elements are important for distinguishing stars in chemical space. We use ˜16 000 red giant and red clump H-band spectra from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and perform polynomial fits to remove trends not due to abundance-ratio variations. Using expectation maximized principal component analysis, we find principal components with high signal in the wavelength regions most important for distinguishing between stars. Different subsamples of red giant and red clump stars are all consistent with needing about 10 principal components to accurately model the spectra above the level of the measurement uncertainties. The dimensionality of stellar chemical space that can be investigated in the H band is therefore ≲10. For APOGEE observations with typical signal-to-noise ratios of 100, the number of chemical space cells within which stars cannot be distinguished is approximately 1010±2 × (5 ± 2)n - 10 with n the number of principal components. This high dimensionality and the fine-grained sampling of chemical space are a promising first step towards chemical tagging based on spectra alone.

Constraints on the tectonics of the Mule Mountains thrust system, southeast California and southwest Arizona

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

Tosdal, R.M.

1990-11-10

The Mule Mountains thrust system crops out discontinuously over a 100-km-strike length in the Blythe-Quartzsite region of southeast California and southwest Arizona. Along the thrust system, middle and upper crustal metamorphic and plutonic rocks of Proterozoic and Mesozoic age are thrust north-northeastward (015{degree} to 035{degree}) over a lower plate metamorphic terrane that formed part of the Proterozoic North American craton, its Paleozoic sedimentary rock cover, overlying Mesozoic volcanic and sedimentary rocks, and the intruding Jurassic and Cretaceous granitic rocks. Stratigraphic, petrologic, and Pb isotopic ties for Jurassic granitoids and for Jurassic( ) and Cretaceous sedimentary rocks across the various partsmore » of the thrust system indicate that related crustal blocks are superposed and preclude it from having large displacements. The thick-skinned thrust system is structurally symmetrical along its length with a central domain of synmetamorphic thrust faults that are flanked by western and eastern domains where lower plate domains where lower plate synclines underlie the thrusts. Deformation occurred under low greenschist facies metamorphic conditions in the upper crust. Movement along the thrust system was probably limited to no more than a few tens of kilometers and occurred between 79{plus minus}2 Ma and 70{plus minus}4 Ma. The superposition of related rocks and the geometry of the thrust system preclude it from being a major tectonic boundary of post-Middle Jurassic age, as has been previously proposed. Rather, the thrust system forms the southern boundary of the narrow zone of Cretaceous intracratonic deformation, and it is one of the last tectonic events in the zone prior to regional cooling.« less

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.

Modules for Experiments in Stellar Astrophysics (MESA): Planets, Oscillations, Rotation, and Massive Stars

NASA Astrophysics Data System (ADS)

Paxton, Bill; Cantiello, Matteo; Arras, Phil; Bildsten, Lars; Brown, Edward F.; Dotter, Aaron; Mankovich, Christopher; Montgomery, M. H.; Stello, Dennis; Timmes, F. X.; Townsend, Richard

2013-09-01

We substantially update the capabilities of the open source software package Modules for Experiments in Stellar Astrophysics (MESA), and its one-dimensional stellar evolution module, MESA star. Improvements in MESA star's ability to model the evolution of giant planets now extends its applicability down to masses as low as one-tenth that of Jupiter. The dramatic improvement in asteroseismology enabled by the space-based Kepler and CoRoT missions motivates our full coupling of the ADIPLS adiabatic pulsation code with MESA star. This also motivates a numerical recasting of the Ledoux criterion that is more easily implemented when many nuclei are present at non-negligible abundances. This impacts the way in which MESA star calculates semi-convective and thermohaline mixing. We exhibit the evolution of 3-8 M ⊙ stars through the end of core He burning, the onset of He thermal pulses, and arrival on the white dwarf cooling sequence. We implement diffusion of angular momentum and chemical abundances that enable calculations of rotating-star models, which we compare thoroughly with earlier work. We introduce a new treatment of radiation-dominated envelopes that allows the uninterrupted evolution of massive stars to core collapse. This enables the generation of new sets of supernovae, long gamma-ray burst, and pair-instability progenitor models. We substantially modify the way in which MESA star solves the fully coupled stellar structure and composition equations, and we show how this has improved the scaling of MESA's calculational speed on multi-core processors. Updates to the modules for equation of state, opacity, nuclear reaction rates, and atmospheric boundary conditions are also provided. We describe the MESA Software Development Kit that packages all the required components needed to form a unified, maintained, and well-validated build environment for MESA. We also highlight a few tools developed by the community for rapid visualization of MESA star results.

Late quaternary out-of-sequence deformation in the innermost Kangra Reentrant, NW Himalaya of India: Seismic potential appraisal from 10Be dated fluvial terraces

NASA Astrophysics Data System (ADS)

Cortés-Aranda, J.; Vassallo, R.; Jomard, H.; Pousse-Beltrán, L.; Astudillo, L.; Mugnier, J.-L.; Jouanne, F.; Malik, M.; Carcaillet, J.

2018-06-01

The Kangra Reentrant is a convex-to-the-northeast U-shaped structure in the NW Himalaya, where the Sub-Himalayan fold-and-thrust belt is ∼90 km wide. This region has not been struck by large earthquakes since the 1905 Mw 7.8 Kangra Earthquake. Out-of-sequence deformation has been reported at the millennial timescale along intracrustal thrusts within this reentrant, such as the Jawalamukhi Thrust. Up to now, the occurrence of out-of-sequence deformation along inner thrusts within the Kangra Reentrant, during the Late Quaternary, has not yet been addressed. In this study, the results of a neotectonic survey undertaken in this reentrant are presented; the studied zone is located between the Beas and the Neogad rivers, and encompasses from the Jawalamukhi Thrust to the Main Boundary Thrust. Two terraces that are deformed by branches of the Medlicott-Wadia Thrust, locally named the Palampur Thrust, are identified; this is evidenced in the field by metric-scale fault scarps. By using 10Be dating, the ages of these terraces were constrained to ca. 7.5 and ca. 6.2 ka. This is clear evidence of the Late Quaternary out-of-sequence deformation in the innermost part of this reentrant, implying that strain is distributed along all the arc-orthogonal extent of the local fold and thrust belt over this timespan. A cumulative slip rate of ca. 1 mm/yr along the studied thrusts, which represents 10% of the bulk-strain accommodated by the whole reentrant for this timespan, is calculated. In spite of the marginal appearance of this figure, this deformation rate is attributed to 7 < Mw < 8 earthquakes triggered along the brittle/ductile zone of Main Himalayan Thrust and emerging at the surface along crustal ramps, such as those represented by the Palampur Thrust in the study area. Earthquakes of this magnitude may severely impact the Kangra District, which currently hosts 1.5 million people.

Thrusting and back-thrusting as post-emplacement kinematics of the Almora klippe: Insights from Low-temperature thermochronology

NASA Astrophysics Data System (ADS)

Patel, R. C.; Singh, Paramjeet; Lal, Nand

2015-06-01

Crystalline klippen over the Lesser Himalayan Sequence (LHS) in the Kumaon and Garhwal regions of NW-Himalaya, are the representative of southern portion of the Main Central Thrust (MCT) hanging wall. These were tectonically transported over the juxtaposed thrust sheets (Berinag, Tons and Ramgarh) of the LHS zone along the MCT. These klippen comprise of NW-SE trending synformal folded thrust sheet bounded by thrusts in the south and north. In the present study, the exhumation histories of two well-known klippen namely Almora and Baijnath, and the Ramgarh thrust sheet, in the Kumaon and Garhwal regions vis-a-vis Himalayan orogeny have been investigated using Apatite Fission Track (AFT) ages. Along a ~ 60 km long orogen perpendicular transect across the Almora klippe and the Ramgarh thrust sheet, 16 AFT cooling ages from the Almora klippe and 2 from the Ramgarh thrust sheet have been found to range from 3.7 ± 0.8 to 13.2 ± 2.7 Ma, and 6.3 ± 0.8 to 7.2 ± 1.0 Ma respectively. From LHS meta-sedimentary rocks only a single AFT age of 3.6 ± 0.8 Ma could be obtained. Three AFT ages from the Baijnath klippe range between 4.7 ± 0.5 and 6.6 ± 0.8 Ma. AFT ages and exhumation rates of different klippen show a dynamic coupling between tectonic and erosion processes in the Kumaon and Garhwal regions of NW-Himalaya. However, the tectonic processes play a dominant role in controlling the exhumation. Thrusting and back thrusting within the Almora klippe and Ramgarh thrust sheet are the post-emplacement kinematics that controlled the exhumation of the Almora klippe. Combining these results with the already published AFT ages from the crystalline klippen and the Higher Himalayan Crystalline (HHC), the kinematics of emplacement of the klippen over the LHS and exhumation pattern across the MCT in the Kumaon and Garhwal regions of NW-Himalaya have been investigated.

Fundamental Understanding of Rotor Aeromechanics at High Advance Ratio Through Wind Tunnel Testing

NASA Astrophysics Data System (ADS)

Berry, Benjamin

The purpose of this research is to further the understanding of rotor aeromechanics at advance ratios (mu) beyond the maximum of 0.5 (ratio of forward airspeed to rotor tip speed) for conventional helicopters. High advance ratio rotors have applications in high speed compound helicopters. In addition to one or more conventional main rotors, these aircraft employ either thrust compounding (propellers), lift compounding (fixed-wings), or both. An articulated 4-bladed model rotor was constructed, instrumented, and tested up to a maximum advance ratio of mu=1.6 in the Glenn L. Martin Wind Tunnel at the University of Maryland. The data set includes steady and unsteady rotor hub forces and moments, blade structural loads, blade flapping angles, swashplate control angles, and unsteady blade pressures. A collective-thrust control reversal--where increasing collective pitch results in lower rotor thrust--was observed and is a unique phenomenon to the high advance ratio flight regime. The thrust reversal is explained in a physical manner as well as through an analytical formulation. The requirements for the occurrence of the thrust reversal are enumerated. The effects of rotor geometry design on the thrust reversal onset are explored through the formulation and compared to the measured data. Reverse-flow dynamic stall was observed to extend the the lifting capability of the edgewise rotor well beyond the expected static stall behavior of the airfoil sections. Through embedded unsteady blade surface pressure transducers, the normal force, pitching moment, and shed dynamic stall vortex time histories at a blade section in strong reverse flow were analyzed. Favorable comparisons with published 2-D pitching airfoil reverse flow dynamic stall data indicate that the 3-D stall environment can likely be predicted using models developed from such 2-D experiments. Vibratory hub loads were observed to increase with advance ratio. Maximum amplitude was observed near mu=1, with a reduction in vibratory loads at higher advance ratios. Blade load 4/rev harmonics dominated due to operation near a 4/rev fanplot crossing of the 2nd flap bending mode natural frequency. Oscillatory loads sharply increase in the presence of retreating blade reverse flow dynamic stall, and are evident in blade torsion, pitch link, and hub load measurements. The blades exhibited torsion moment vibrations at the frequency of the 1st torsion mode in response to the reverse flow pitching moment loading.

Numerical modeling of fold-and-thrust belts: Applications to Kuqa foreland fold belt, China

NASA Astrophysics Data System (ADS)

Yin, H.; Morgan, J. K.; Zhang, J.; Wang, Z.

2009-12-01

We constructed discrete element models to simulate the evolution of fold-and-thrust belts. The impact of rock competence and decollement strength on the geometric pattern and deformation mechanics of fold-and-thrust belts has been investigated. The models reproduced some characteristic features of fold-and-thrust belts, such as faulted detachment folds, pop-ups, far-traveled thrust sheets, passive-roof duplexes, and back thrusts. In general, deformation propagates farther above a weak decollement than above a strong decollement. Our model results confirm that fold-and-thrust belts with strong frictional decollements develop relatively steep and narrow wedges formed by closely spaced imbricate thrust slices, whereas fold belts with weak decollements form wide low-taper wedges composed of faulted detachment folds, pop-ups, and back thrusts. Far-traveled thrust sheets and passive-roof duplexes are observed in the model with a strong lower decollement and a weak upper detachment. Model results also indicate that the thickness of the weak layer is critical. If it is thick enough, it acts as a ductile layer that is able to flow under differential stress, which helps to partition deformation above and below it. The discrete element modeling results were used to interpret the evolution of Kuqa Cenozoic fold-and-thrust belt along northern Tarim basin, China. Seismic and well data show that the widely distributed Paleogene rock salt has a significant impact on the deformation in this area. Structures beneath salt are closely spaced imbricate thrust and passive-roof duplex systems. Deformation above salt propagates much farther than below the salt. Faults above salt are relatively wide spaced. A huge controversy over the Kuqa fold-and-thrust belt is whether it is thin-skinned or thick-skinned. With the insights from DEM results, we suggest that Kuqa structures are mostly thin-skinned with Paleogene salt as decollement, except for the rear part near the backstop, where the faults below the salt are thick-skinned and involve the Paleozoic basement. We think that most basement-involved sub-salt faults, if not all, formed later than the above salt-detached thin-skinned structures.

Precision Astrophysics Experiments with the Kepler Satellite

NASA Astrophysics Data System (ADS)

Jackiewicz, Jason

2012-10-01

Long photometric observations from space of tens of thousands of stars, such as those provided by Kepler, offer unique opportunities to carry out ensemble astrophysics as well as detailed studies of individual objects. One of the primary tools at our disposal for understanding pulsating stars is asteroseismology, which uses observed stellar oscillation frequencies to determine interior properties. This can provide very strict constraints on theories of stellar evolution, structure, and the population characteristics of stars in the Milky Way galaxy. This talk will focus on several of the exciting insights Kepler has enabled through asteroseismology of stars across the H-R diagram.

Construction of Database for Pulsating Variable Stars

NASA Astrophysics Data System (ADS)

Chen, B. Q.; Yang, M.; Jiang, B. W.

2011-07-01

A database for the pulsating variable stars is constructed for Chinese astronomers to study the variable stars conveniently. The database includes about 230000 variable stars in the Galactic bulge, LMC and SMC observed by the MACHO (MAssive Compact Halo Objects) and OGLE (Optical Gravitational Lensing Experiment) projects at present. The software used for the construction is LAMP, i.e., Linux+Apache+MySQL+PHP. A web page is provided to search the photometric data and the light curve in the database through the right ascension and declination of the object. More data will be incorporated into the database.

A study of variable thrust, variable specific impulse trajectories for solar system exploration

NASA Astrophysics Data System (ADS)

Sakai, Tadashi

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines; but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.

Recent highlights from STAR

NASA Astrophysics Data System (ADS)

Zha, Wangmei

2018-02-01

The Solenoidal Tracker at RHIC (STAR) experiment takes advantage of its excellent tracking and particle identification capabilities at mid-rapidity to explore the properties of strongly interacting QCD matter created in heavy-ion collisions at RHIC. The STAR collaboration presented 7 parallel and 2 plenary talks at Strangeness in Quark Matter 2017 and covered various topics including heavy flavor measurements, bulk observables, electro-magnetic probes and the upgrade program. This paper highlights some of the selected results.

Star ratings. Stars of wonder.

PubMed

Dawes, David

2002-09-12

Analysis of trusts that changed their star-rating over the past two years indicates that a change of chief executive was not a significant factor. The length of time in post and the experience of the chief executive were also insignificant. This has serious implications for the theory behind franchising and the evaluation of franchised trusts. Holding chief executives to account for the organisation's performance within their first 12 months is unlikely to be effective.

Thrust-ridge paleodepositional model for the Upper Freeport coal bed and associated clastic facies, Upper Potomac coal field, Appalachian Basin, U.S.A.

USGS Publications Warehouse

Belt, Edward S.; Lyons, P.C.

1990-01-01

Two differential depositional sequences are recognized within a 37-m-thick lowermost section of the Conemaugh Group of Late Pennsylvanian (Westphalian D) age in the southern part of the Upper Potomac coal field (panhandle of Maryland and adjacent West Virginia). The first sequence is dominated by the Upper Freeport coal bed and zone (UF); the UF consists of a complex of interfingered thick coal beds and mudrocks. The UF underlies the entire 500 km2 study area (approximately 40 km in a NE-SW direction). The second sequence is dominated by medium- to coarse-grained sandstone and pebbly sandstone. They were deposited in channel belts that cut into and interfingered laterally with mudrock and fine- to medium-grained sandstone facies of floodbasin and crevasse-lobe origin. Thin lenticular coals occur in the second sequence. Nowhere in the study area does coarse-grained sandstone similar to the sandstone of the channel belts of the second sequence occur within the UF. However, 20 km north of the study area, coarse channel belts are found that are apparently synchronous with the UF (Lyons et al., 1984). The southeastern margin of the study are is bounded by the Allegheny Front. Between it and the North Mountain thrust (75 km to the southeast), lie at least eight other thrusts of unknown extent (Wilson, 1887). All these thrusts are oriented northwest; Devonian and older strata are exposed at the surface between the Allegheny Front and the North Mountain thrust. A blind-thrust ridge model is proposed to explain the relation of the two markedly depositional sequences to the thrusts that lie to the southeast of the Upper Potomac coal field. This model indicates that thrust ridges diverted coarse clastics from entering the swamp during a period when the thick Upper Freeport peat accumulated. Anticlinal thrust ridges and associated depressions are envisioned to have developed parallel to the Appalachian orogen during Middle and early Late Pennsylvanian time. A blind thrust developed from one of the outboard ridges, and it was thrust farther outboard ahead of the main body of the orogen. Sediment derived from the orogen was diverted into a sediment trap inboard of the ridge (Fig. 1). The ridge prevented sediment from entering the main peat-forming swamp. Sediment shed from the orogen accumulated in the sediment trap was carried out of the ends of the trap by steams that occupied the shear zone at the ends of the blind-thrust ridge (Fig. 1). Remnants of blind-thrust ridges occurs in the Sequatchie Valley thrust and the Pine Mountain thrust of the southern Appalachians. The extent, parallel to the orogen, of the thick areally extensive UF coal is related to the length of the blind-thrust ridge that, in turn, controlled the spacing of the river-derived coarse clastics that entered the main basin from the east. Further tectonism caused the thrust plane to emerge to the surface of the blind-thrust ridge. Peat accumulation was then terminated by the rapid erosion of the blind-thrust ridge and by the release of trapped sediment behind it. The peat was buried by sediments from streams from closely spaced channel belts] with intervening floodbasins. The model was implications for widespread peat (coal) deposits that developed in tropical regions, a few hundred kilometers inland from the sea during Pennsylvanian time (Belt and Lyons, 1989). ?? 1990.

Computation of optimal Mars trajectories via combined chemical/electrical propulsion, Part 3: Compromise solutions

NASA Astrophysics Data System (ADS)

Miele, A.; Wang, T.; Williams, P. N.

2005-12-01

The success of the solar-electric ion engine powering the DS1 spacecraft has paved the way toward the use of low-thrust electrical engines in future planetary/interplanetary missions. Vis-à-vis a chemical engine, an electrical engine has a higher specific impulse, implying a possible decrease in propellant mass; however, the low-thrust aspect discourages the use of an electrical engine in the near-planet phases of a trip, since this might result in an increase in flight time. Therefore, a fundamental design problem is to find the best combination of chemical propulsion and electrical propulsion for a given mission, for example, a mission from Earth to Mars. With this in mind, this paper is the third of a series dealing with the optimization of Earth Mars missions via the use of hybrid engines, namely the combination of high-thrust chemical engines for planetary flight and low-thrust electrical engines for interplanetary flight. We look at the deep-space interplanetary portion of the trajectory under rather idealized conditions. The two major performance indexes, the propellant mass and the flight time, are in conflict with one another for the following reason: any attempt at reducing the former causes an increase in the latter and vice versa. Therefore, it is natural to consider a compromise performance index involving the scaled values of the propellant mass and flight time weighted respectively by the compromise factor C and its complement 1-C. We use the compromise factor as the parameter of the one-parameter family of compromise trajectories. Analyses carried out with the sequential gradient-restoration algorithm for optimal control problems lead to results which can be highlighted as follows. Thrust profile. Generally speaking, the thrust profile of the compromise trajectory includes three subarcs: the first subarc is characterized by maximum thrust in conjunction with positive (upward) thrust direction; the second subarc is characterized by zero thrust (coasting flight); the third subarc is characterized by maximum thrust in conjunction with negative (downward) thrust direction. Effect of the compromise factor. As the compromise factor increases, the propellant mass decreases and the flight time increases; correspondingly, the following changes in the thrust profile take place: (a) the time lengths of the first and third subarcs (powered phases) decrease slightly, meaning that thrust application occurs for shorter duration; also, the average value of the thrust direction in the first and third subarcs decreases, implying higher efficiency of thrust application wrt the spacecraft energy level; as a result, the total propellant mass decreases; (b) the time length of the second subarc (coasting) increases considerably, resulting in total time increase. Minimum time trajectory. If C=0, the resulting minimum time trajectory has the following characteristics: (a) the time length of the coasting subarc reduces to zero and the three-subarc trajectory degenerates into a two-subarc trajectory; (b) maximum thrust is applied at all times and the thrust direction switches from upward to downward at midcourse. Minimum propellant mass trajectory. If C=1, the resulting minimum propellant mass trajectory has the following characteristics: (a) the thrust magnitude has a bang-zero-bang profile; (b) for the powered subarcs, the thrust direction is tangent to the flight path at all times.

The mass-lifetime relation

NASA Astrophysics Data System (ADS)

LoPresto, Michael C.

2018-05-01

In a recent "AstroNote," I described a simple exercise on the mass-luminosity relation for main sequence stars as an example of exposing students in a general education science course of lower mathematical level to the use of quantitative skills such as collecting and analyzing data. Here I present another attempt at a meaningful experience for such students that again involves both the gathering and analysis of numerical data and comparison with accepted result, this time on the relationship of the mass and lifetimes of main sequence stars. This experiment can stand alone or be used as an extension of the previous mass-luminosity relationship experiment.

Laser experiments to simulate coronal mass ejection driven magnetospheres and astrophysical plasma winds on compact magnetized stars

NASA Astrophysics Data System (ADS)

Horton, W.; Ditmire, T.; Zakharov, Yu. P.

2010-06-01

Laboratory experiments using a plasma wind generated by laser-target interaction are proposed to investigate the creation of a shock in front of the magnetosphere and the dynamo mechanism for creating plasma currents and voltages. Preliminary experiments are shown where measurements of the electron density gradients surrounding the obstacles are recorded to infer the plasma winds. The proposed experiments are relevant to understanding the electron acceleration mechanisms taking place in shock-driven magnetic dipole confined plasmas surrounding compact magnetized stars and planets. Exploratory experiments have been published [P. Brady, T. Ditmire, W. Horton, et al., Phys. Plasmas 16, 043112 (2009)] with the one Joule Yoga laser and centimeter sized permanent magnets.

Analysis of flow decay potential on Galileo. [oxidizer flow rate reduction by iron nitrate precipitates

NASA Technical Reports Server (NTRS)

Cole, T. W.; Frisbee, R. H.; Yavrouian, A. H.

1987-01-01

The risks posed to the NASA's Galileo spacecraft by the oxidizer flow decay during its extended mission to Jupiter is discussed. The Galileo spacecraft will use nitrogen tetroxide (NTO)/monomethyl hydrazine bipropellant system with one large engine thrust-rated at a nominal 400 N, and 12 smaller engines each thrust-rated at a nominal 10 N. These smaller thrusters, because of their small valve inlet filters and small injector ports, are especially vulnerable to clogging by iron nitrate precipitates formed by NTO-wetted stainless steel components. To quantify the corrosion rates and solubility levels which will be seen during the Galileo mission, corrosion and solubility testing experiments were performed with simulated Galileo materials, propellants, and environments. The results show the potential benefits of propellant sieving in terms of iron and water impurity reduction.

Experimental investigation of a unique airbreathing pulsed laser propulsion concept

NASA Technical Reports Server (NTRS)

Myrabo, L. N.; Nagamatsu, H. T.; Manka, C.; Lyons, P. W.; Jones, R. A.

1991-01-01

Investigations were conducted into unique methods of converting pulsed laser energy into propulsive thrust across a flat impulse surface under atmospheric conditions. The propulsion experiments were performed with a 1-micron neodymium-glass laser at the Space Plasma Branch of the Naval Research Laboratory. Laser-induced impulse was measured dynamically by ballistic pendulums and statically using piezoelectric pressure transducers on a stationary impulse surface. The principal goal was to explore methods for increasing the impulse coupling performance of airbreathing laser-propulsion engines. A magnetohydrodynamic thrust augmentation effect was discovered when a tesla-level magnetic field was applied perpendicular to the impulse surface. The impulse coupling coefficient performance doubled and continued to improve with increasing laser-pulse energies. The resultant performance of 180 to 200 N-s/MJ was found to be comparable to that of the earliest afterburning turbojets.

Experimental study on combustion modes and thrust performance of a staged-combustor of the scramjet with dual-strut

NASA Astrophysics Data System (ADS)

Yang, Qingchun; Chetehouna, Khaled; Gascoin, Nicolas; Bao, Wen

2016-05-01

To enable the scramjet operate in a wider flight Mach number, a staged-combustor with dual-strut is introduced to hold more heat release at low flight Mach conditions. The behavior of mode transition was examined using a direct-connect model scramjet experiment along with pressure measurements. The typical operating modes of the staged-combustor are analyzed. Fuel injection scheme has a significant effect on the combustor operating modes, particularly for the supersonic combustion mode. Thrust performances of the combustor with different combustion modes and fuel distributions are reported in this paper. The first-staged strut injection has a better engine performance in the operation of subsonic combustion mode. On the contrast, the second-staged strut injection has a better engine performance in the operation of supersonic combustion mode.

Use of an approximate similarity principle for the thermal scaling of a full-scale thrust augmenting ejector

NASA Technical Reports Server (NTRS)

Barankiewicz, Wendy S.; Perusek, Gail P.; Ibrahim, Mounir B.

1992-01-01

Full temperature ejector model simulations are expensive, and difficult to implement experimentally. If an approximate similarity principle could be established, properly chosen performance parameters should be similar for both hot and cold flow tests if the initial Mach number and total pressures of the flow field are held constant. Existing ejector data is used to explore the utility of one particular similarity principle; the Munk and Prim similarity principle for isentropic flows. Static performance test data for a full-scale thrust augmenting ejector are analyzed for primary flow temperatures up to 1560 R. At different primary temperatures, exit pressure contours are compared for similarity. A nondimensional flow parameter is then used to eliminate primary nozzle temperature dependence and verify similarity between the hot and cold flow experiments.

Use of an approximate similarity principle for the thermal scaling of a full-scale thrust augmenting ejector

NASA Technical Reports Server (NTRS)

Barankiewicz, Wendy; Perusek, Gail P.; Ibrahim, Mounir

1992-01-01

Full temperature ejector model simulations are expensive, and difficult to implement experimentally. If an approximate similarity principle could be established, properly chosen performance parameters should be similar for both hot and cold flow tests if the initial Mach number and total pressures of the flow field are held constant. Existing ejector data is used to explore the utility of one particular similarity principle; the Munk and Prim similarity principle for isentropic flows. Static performance test data for a full-scale thrust augmenting ejector are analyzed for primary flow temperatures up to 1560 R. At different primary temperatures, exit pressure contours are compared for similarity. A nondimensional flow paramenter is then used to eliminate primary nozzle temperature dependence and verify similarity between the hot and cold flow experiments.

Prediction and measurement of low-frequency harmonic noise of a hovering model helicopter rotor

NASA Technical Reports Server (NTRS)

Aggarawal, H. R.; Schmitz, F. H.; Boxwell, D. A.

1989-01-01

Far-field acoustic data for a model helicopter rotor have been gathered in a large open-jet, acoustically treated wind tunnel with the rotor operating in hover and out of ground-effect. The four-bladed Boeing 360 model rotor with advanced airfoils, planform, and tip shape was run over a range of conditions typical of today's modern helicopter main rotor. Near in-plane acoustic measurements were compared with two independent implementations of classical linear theory. Measured steady thrust and torque were used together with a free-wake analysis (to predict the thrust and drag distributions along the rotor radius) as input to this first-principles theoretical approach. Good agreement between theory and experiment was shown for both amplitude and phase for measurements made in those positions that minimized distortion of the radiated acoustic signature at low-frequencies.

Gamma-ray line emission from Al-26 produced by Wolf-Rayet stars

NASA Technical Reports Server (NTRS)

Prantzos, N.; Casse, M.; Gros, M.; Doom, C.; Arnould, M.

1985-01-01

The recent satellite observations of the 1.8 MeV line from the decay of Al-26 has given a new impetus to the study of the nucleosynthesis of Al-26. The production and ejection of Al-26 by massive mass-losing stars (Of and WR stars) is discussed in the light of recent stellar models. The longitude distribution of the Al-26 gamma ray line emission produced by the galactic collection of WR stars is derived based on various estimates of their radial distribution. This longitude profile provides: (1) a specific signature of massive stars on the background of other potential Al-26 sources, as novae, supernovae, certain red giants and possibly AGB stars; and (2) a possible tool to improve the data analysis of the HEAO 3 and SMM experiments.

The Clusters AgeS Experiment (CASE). Variable stars in the field of the globular cluster NGC 362

NASA Astrophysics Data System (ADS)

Rozyczka, M.; Thompson, I. B.; Narloch, W.; Pych, W.; Schwarzenberg-Czerny, A.

2016-09-01

The field of the globular cluster NGC 362 was monitored between 1997 and 2015 in a search for variable stars. BV light curves were obtained for 151 periodic or likely periodic variable stars, over a hundred of which are new detections. Twelve newly detected variable stars are proper-motion members of the cluster: two SX Phe and two RR Lyr pulsators, one contact binary, three detached or semi-detached eclipsing binaries, and four spotted variable stars. The most interesting objects among these are the binary blue straggler V20 with an asymmetric light curve, and the 8.1 d semidetached binary V24 located on the red giant branch of NGC 362, which is a Chandra X-ray source. We also provide substantial new data for 24 previously known variable stars.

Exploring Education-Related Use of Social Media: Business Students Perspectives in a Changing India

ERIC Educational Resources Information Center

Bharucha, Jehangir

2018-01-01

Purpose: Within a connectivist learning model, the purpose of this paper is to investigate the adoption of social media for educational purposes in India, a hitherto unexplored area of research. The basic research thrust is on students' experiences when social media is incorporated into higher education. This research tries to gather evidence on…

Solid rocket motor certification to meet space shuttle requirements from challenge to achievement

NASA Technical Reports Server (NTRS)

Miller, J. Q.; Kilminster, J. C.

1985-01-01

Three solid rocket motor (SRM) design requirements for the Space Shuttle were discussed. No existing solid rocket motor experience was available for the requirement for a thrust-time trace, twenty uses for the principle hardware, and a moveable nozzle with an 8 deg. omnivaxial vectoring capability. The solutions to these problems are presented.

Tactical Combat Casualty Care 2007: Evolving Concepts and Battlefield Experience

DTIC Science & Technology

2007-11-01

airway obstruction: chin lift or jaw thrust, nasopharyngeal airway, place casualty in recovery position Surgical cricothyroidotomy (with lidocaine ...laryngeal mask airway /ILMA or Combitube or endotracheal intubation or surgical cricothyroidotomy (with lidocaine if conscious) Spinal immobilization is...surgical cricothyroidotomy (with lidocaine If conscious) 3. Breathing Consider tension pneumothorax and decompress with needle thoracostomy if

Ever Fly a Tetrahedron?

ERIC Educational Resources Information Center

King, Kenneth

2004-01-01

Few things capture the spirit of spring like flying a kite. Watching a kite dance and sail across a cloud spotted sky is not only a visually appealing experience it also provides a foundation for studies in science and mathematics. Put simply, a kite is an airfoil surface that flies when the forces of lift and thrust are greater than the forces of…

Team Teaching and Cooperative Groups in Abstract Algebra: Nurturing a New Generation of Confident Mathematics Teachers

ERIC Educational Resources Information Center

Grassl, R.; Mingus, T. T. Y.

2007-01-01

Experiences in designing and teaching a reformed abstract algebra course are described. This effort was partially a result of a five year statewide National Science Foundation (NSF) grant entitled the Rocky Mountain Teacher Enhancement Collaborative. The major thrust of this grant was to implement reform in core mathematics courses that would…

Automated Design of Multiphase Space Missions Using Hybrid Optimal Control

ERIC Educational Resources Information Center

Chilan, Christian Miguel

2009-01-01

A modern space mission is assembled from multiple phases or events such as impulsive maneuvers, coast arcs, thrust arcs and planetary flybys. Traditionally, a mission planner would resort to intuition and experience to develop a sequence of events for the multiphase mission and to find the space trajectory that minimizes propellant use by solving…

StAR Protein Stability in Y1 and Kin-8 Mouse Adrenocortical Cells.

PubMed

Clark, Barbara J; Hudson, Elizabeth A

2015-03-04

The steroidogenic acute regulatory protein (STAR) protein expression is required for cholesterol transport into mitochondria to initiate steroidogenesis in the adrenal and gonads. STAR is synthesized as a 37 kDa precursor protein which is targeted to the mitochondria and imported and processed to an intra-mitochondrial 30 kDa protein. Tropic hormone stimulation of the cAMP-dependent protein kinase A (PKA) signaling pathway is the major contributor to the transcriptional and post-transcriptional regulation of STAR synthesis. Many studies have focused on the mechanisms of cAMP-PKA mediated control of STAR synthesis while there are few reports on STAR degradation pathways. The objective of this study was to determine the effect of cAMP-PKA-dependent signaling on STAR protein stability. We have used the cAMP-PKA responsive Y1 mouse adrenocortical cells and the PKA-deficient Kin-8 cells to measure STAR phosphorylation and protein half-life. Western blot analysis and standard radiolabeled pulse-chase experiments were used to determine STAR phosphorylation status and protein half-life, respectively. Our data demonstrate that PKA-dependent STAR phosphorylation does not contribute to 30 kDa STAR protein stability in the mitochondria. We further show that inhibition of the 26S proteasome does not block precursor STAR phosphorylation or steroid production in Y1 cells. These data suggest STAR can maintain function and promote steroidogenesis under conditions of proteasome inhibition.

StAR Protein Stability in Y1 and Kin-8 Mouse Adrenocortical Cells

PubMed Central

Clark, Barbara J.; Hudson, Elizabeth A.

2015-01-01

The steroidogenic acute regulatory protein (STAR) protein expression is required for cholesterol transport into mitochondria to initiate steroidogenesis in the adrenal and gonads. STAR is synthesized as a 37 kDa precursor protein which is targeted to the mitochondria and imported and processed to an intra-mitochondrial 30 kDa protein. Tropic hormone stimulation of the cAMP-dependent protein kinase A (PKA) signaling pathway is the major contributor to the transcriptional and post-transcriptional regulation of STAR synthesis. Many studies have focused on the mechanisms of cAMP-PKA mediated control of STAR synthesis while there are few reports on STAR degradation pathways. The objective of this study was to determine the effect of cAMP-PKA-dependent signaling on STAR protein stability. We have used the cAMP-PKA responsive Y1 mouse adrenocortical cells and the PKA-deficient Kin-8 cells to measure STAR phosphorylation and protein half-life. Western blot analysis and standard radiolabeled pulse-chase experiments were used to determine STAR phosphorylation status and protein half-life, respectively. Our data demonstrate that PKA-dependent STAR phosphorylation does not contribute to 30 kDa STAR protein stability in the mitochondria. We further show that inhibition of the 26S proteasome does not block precursor STAR phosphorylation or steroid production in Y1 cells. These data suggest STAR can maintain function and promote steroidogenesis under conditions of proteasome inhibition. PMID:25749137

Analogue models of progressive arcs: insights into the kinematics of Mediterranean orogens as view from the Gibraltar Arc System (GAS)

NASA Astrophysics Data System (ADS)

Jiménez-Bonilla, Alejandro; Crespo, Ana; Balanyá, Juan Carlos; Expósito, Inmaculada; Díaz-Azpiroz, Manuel

2017-04-01

The western Mediterranean orogenic belt is characterized by two arcs marked by their extremely tight trend-line pattern. Both arcs, Gibraltar and Calabria arcs, show a similar kinematic pattern of extension in their internal zones associated with the development of a back-arc basin approximately counterweighted by outward radial thrusting in their external zones. At the same time, opposite vertical-axis rotations at the arc limbs have been reported. Our case study is the Gibraltar Arc System (GAS), a highly protruded arc in which differential vertical-axis rotations of hundreds of kilometer-scale blocks have been identified. During the last 10 Ma, these differential rotations reach 70° in the westernmost part of the arc [1]. Consequently, the GAS external zone was deformed into a curved fold-and-thrust belt. To look into the geometry, kinematics and progressive deformation of the GAS fold-and-thrust belt -which is detached within an evaporitic-rich layer-, analogue models were performed employing a deformable plastic strip that is able to increase its protrusion grade during the experiment. Three types of set-ups were made using: (1) a 66cm x 51cm initial parallelepiped built only with a sand layer; (2) a 66cm x 51cm initial parallelepiped floored by ductile layer of silicone of variable thickness overlaid by sand; (3) a 100cm x 65cm initial parallelepiped floored by silicone overlaid by sand. In all the experiments, the parallelepiped was deformed into a curved fold-and-thrust belt with outward radial transport direction. The thicker the silicone layer is, the more frequent backthrusting is and the more noticeable the lack of cylindrism is. During the progression of the deformation, the arc-parallel lengthening was achieved by arc-perpendicular normal faults and oblique, conjugate strike-slip faults, which individualized blocks that rotated independently in the second and third set of models. Grid markers rotated clockwise and anticlockwise at the left and right limbs of the apex, respectively, ca. 25° in the first set, between 25° and 40° in the second and more than 70° in the third one. These results differ from previous analogue experiments that used a rigid backstop with different shapes and a straight motion (e.g. [2]), in which it was impossible to generate highly divergent tectonic transport around the indenter. The models we present are the first analogue models of progressive arcs with an indenter that deforms in map view during the experiment progresses. The model results permit us to test the influence of such type of indenter on the shaping of Mediterranean arcs, such as the Gibraltar Arc System external wedge, and in general, of other progressive arcs on Earth, in terms of kinematics, geometry, size of the individualized blocks and rotation of passive markers. [1] Crespo-Blanc A., Comas, M., Balanyá J.C. (2016) Clues for a Tortonian reconstruction of the Gibraltar Arc: Structural pattern, deformation diachronism and block rotations. Tectonophysics, 2016, 683, 308-324. [2] Crespo-Blanc A., González-Sánchez, A., 2005. Influence of indenter geometry on arcuate fold-and-thrust wedge: preliminary results of analogue modelling, Geogaceta 37, 11-14. Acknowledgements: RNM-415, CGL-2013-46368-P and EST1/00231.

14 CFR 25.1155 - Reverse thrust and propeller pitch settings below the flight regime.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Reverse thrust and propeller pitch settings... Powerplant Controls and Accessories § 25.1155 Reverse thrust and propeller pitch settings below the flight regime. Each control for reverse thrust and for propeller pitch settings below the flight regime must...

14 CFR 25.1155 - Reverse thrust and propeller pitch settings below the flight regime.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Reverse thrust and propeller pitch settings... Powerplant Controls and Accessories § 25.1155 Reverse thrust and propeller pitch settings below the flight regime. Each control for reverse thrust and for propeller pitch settings below the flight regime must...

14 CFR 25.1155 - Reverse thrust and propeller pitch settings below the flight regime.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Reverse thrust and propeller pitch settings... Powerplant Controls and Accessories § 25.1155 Reverse thrust and propeller pitch settings below the flight regime. Each control for reverse thrust and for propeller pitch settings below the flight regime must...

14 CFR 25.1155 - Reverse thrust and propeller pitch settings below the flight regime.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Reverse thrust and propeller pitch settings... Powerplant Controls and Accessories § 25.1155 Reverse thrust and propeller pitch settings below the flight regime. Each control for reverse thrust and for propeller pitch settings below the flight regime must...

14 CFR 25.1155 - Reverse thrust and propeller pitch settings below the flight regime.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Reverse thrust and propeller pitch settings... Powerplant Controls and Accessories § 25.1155 Reverse thrust and propeller pitch settings below the flight regime. Each control for reverse thrust and for propeller pitch settings below the flight regime must...

14 CFR 33.201 - Design and test requirements for Early ETOPS eligibility.

Code of Federal Regulations, 2012 CFR

2012-01-01

... maintenance errors that could result in an IFSD, loss of thrust control, or other power loss. (b) The design features of the engine must address problems shown to result in an IFSD, loss of thrust control, or other...-off, climb, cruise, descent, approach, and landing thrust or power and the use of thrust reverse (if...

14 CFR 33.201 - Design and test requirements for Early ETOPS eligibility.

Code of Federal Regulations, 2011 CFR

2011-01-01

... maintenance errors that could result in an IFSD, loss of thrust control, or other power loss. (b) The design features of the engine must address problems shown to result in an IFSD, loss of thrust control, or other...-off, climb, cruise, descent, approach, and landing thrust or power and the use of thrust reverse (if...

14 CFR 33.201 - Design and test requirements for Early ETOPS eligibility.

Code of Federal Regulations, 2013 CFR

2013-01-01

... maintenance errors that could result in an IFSD, loss of thrust control, or other power loss. (b) The design features of the engine must address problems shown to result in an IFSD, loss of thrust control, or other...-off, climb, cruise, descent, approach, and landing thrust or power and the use of thrust reverse (if...

Experience from the construction and operation of the STAR PXL detector

NASA Astrophysics Data System (ADS)

Greiner, L.; Anderssen, E. C.; Contin, G.; Schambach, J.; Silber, J.; Stezelberger, T.; Sun, X.; Szelezniak, M.; Vu, C.; Wieman, H. H.; Woodmansee, S.

2015-04-01

A new silicon based vertex detector called the Heavy Flavor Tracker (HFT) was installed at the Soleniodal Tracker At RHIC (STAR) experiment for the Relativistic Heavy Ion Collider (RHIC) 2014 heavy ion run to improve the vertex resolution and extend the measurement capabilities of STAR in the heavy flavor domain. The HFT consists of four concentric cylinders around the STAR interaction point composed of three different silicon detector technologies based on strips, pads and for the first time in an accelerator experiment CMOS monolithic active pixels (MAPS) . The two innermost layers at a radius of 2.8 cm and 8 cm from the beam line are constructed with 400 high resolution MAPS sensors arranged in 10-sensor ladders mounted on 10 thin carbon fiber sectors giving a total silicon area of 0.16 m2. Each sensor consists of a pixel array of nearly 1 million pixels with a pitch of 20.7 μm with column-level discriminators, zero-suppression circuitry and output buffer memory integrated into one silicon die with a sensitive area of ~ 3.8 cm2. The pixel (PXL) detector has a low power dissipation of 170 mW/cm2, which allows air cooling. This results in a global material budget of 0.5% radiation length per layer for detector used in this run. A novel mechanical approach to detector insertion allows for the installation and integration of the pixel sub detector within a 12 hour period during an on-going STAR run. The detector specifications, experience from the construction and operation, lessons learned and initial measurements of the PXL performance in the 200 GeV Au-Au run will be presented.

Neutron star matter equation of state: current status and challenges

NASA Astrophysics Data System (ADS)

Ohnishi, Akira

2014-09-01

Neutron star matter has a variety of constituents and structures depending on the density; neutron-rich nuclei surounded by electrons and drip neutrons in the crust, pasta nuclei at the bottom of inner crust, and uniform isospin-asymmetric nuclear matter in a superfluid state in the outer core. In the inner core, the neutron Fermi energy becomes so large that exotic constituents such as hyperons, mesons and quarks may emerge. Radioactive beam and hypernuclear experiments provide information on the symmetry energy and superfluidity in the crust and outer core and on the hyperon potentials in the inner core, respectively. Cold atom experiments are also helpful to understand pure neutron matter, which may be simulated by the unitary gas. An equation of state (EOS) constructed based on these laboratory experiments has to be verified by the astronomical observations such as the mass, radius, and oscillations of neutron stars. One of the key but missing ingredients is the three-baryon interactions such as the hyperon-hyperon-nucleon (YYN) interaction. YYN interaction is important in order to explain the recently discovered massive neutron stars consistently with laboratory experiments. We have recently found that the ΛΛ interaction extracted from the ΛΛ correlation at RHIC is somewhat stronger than that from double Λ hypernuclei. Since these two interactions corresponds to the vacuum and in-medium ΛΛ interactions, respectively, the difference may tell us a possible way to access the YYN interaction based on experimental data. In the presentation, after a review on the current status of neutron star matter EOS studies, we discuss the necessary tasks to pin down the EOS. We also present our recent study of ΛΛ interaction from correlation data at RHIC.

Space shuttle orbit maneuvering engine reusable thrust chamber program

NASA Technical Reports Server (NTRS)

Senneff, J. M.

1975-01-01

The feasibility of potential reusable thrust chamber concepts is studied. Propellant condidates were examined and analytically combined with potential cooling schemes. A data base of engine data which would assist in a configuration selection was produced. The data base verification was performed by the demonstration of a thrust chamber of a selected coolant scheme design. A full scale insulated columbium thrust chamber was used for propellant coolant configurations. Combustion stability of the injectors and a reduced size thrust chamber were experimentally verified as proof of concept demonstrations of the design and study results.

Cryogenic liquid resettlement activated by impulsive thrust in space-based propulsion system

NASA Technical Reports Server (NTRS)

Hung, R. J.; Shyu, K. L.

1991-01-01

The purpose of present study is to investigate most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. Comparison between the constant reverse gravity acceleration and impulsive reverse gravity acceleration to be used for the activation of propellant resettlement, it shows that impulsive reverse gravity thrust is superior to constant reverse gravity thrust for liquid reorientation in a reduced gravity environment. Comparison among impulsive reverse gravity thrust with 0.1, 1.0 and 10 Hz frequencies for liquid filled level in the range between 30 to 80 percent, it shows that the selection of 1.0 Hz frequency impulsive thrust over the other frequency ranges of impulsive thrust is most proper based on the present study.

Cryogenic liquid resettlement activated by impulsive thrust in space-based propulsion system

NASA Technical Reports Server (NTRS)

Hung, R. J.; Shyu, K. L.

1991-01-01

The purpose of present study is to investigate the most efficient technique for propellant resettling through the minimization of propellant usage and weight penalties. Comparison between the constant reverse gravity acceleration and impulsive reverse gravity acceleration to be used for the activation of propellant resettlement shows that impulsive reverse gravity thrust is superior to constant reverse gravity thrust for liquid reorientation in a reduced gravity environment. Comparison among impulsive reverse gravity thrust with 0.1, 1.0, and 10 Hz frequencies for liquid-filled level in the range between 30 to 80 percent shows that the selection of a medium frequency of 1.0 Hz impulsive thrust over the other frequency ranges of impulsive thrust is the most proper.

Measurement of the Differential and Total Thrust and Torque of Six Full-Scale Adjustable-Pitch Propellers

NASA Technical Reports Server (NTRS)

Stickle, George W

1933-01-01

Force measurements giving total thrust and torque, and propeller slip stream surveys giving differential thrust and torque were simultaneously made on each of six full-scale propellers in the 20-foot propeller-research tunnel of the National Advisory Committee for Aeronautics. They were adjustable-pitch metal propellers 9.5 feet in diameter; three had modified Clark Y blade sections and three had modified RAF-6 blade sections. This report gives the differential thrust and torque and the variation caused by changing the propeller tip speed and the pitch setting. The total thrust and torque obtained from integration of the thrust and torque distribution curves are compared with those obtained by direct force measurements.

An Undergraduate Research Experience on Studying Variable Stars

NASA Astrophysics Data System (ADS)

Amaral, A.; Percy, J. R.

2016-06-01

We describe and evaluate a summer undergraduate research project and experience by one of us (AA), under the supervision of the other (JP). The aim of the project was to sample current approaches to analyzing variable star data, and topics related to the study of Mira variable stars and their astrophysical importance. This project was done through the Summer Undergraduate Research Program (SURP) in astronomy at the University of Toronto. SURP allowed undergraduate students to explore and learn about many topics within astronomy and astrophysics, from instrumentation to cosmology. SURP introduced students to key skills which are essential for students hoping to pursue graduate studies in any scientific field. Variable stars proved to be an excellent topic for a research project. For beginners to independent research, it introduces key concepts in research such as critical thinking and problem solving, while illuminating previously learned topics in stellar physics. The focus of this summer project was to compare observations with structural and evolutionary models, including modelling the random walk behavior exhibited in the (O-C) diagrams of most Mira stars. We found that the random walk could be modelled by using random fluctuations of the period. This explanation agreed well with observations.

Physics of the Stars

ERIC Educational Resources Information Center

Haig, G. Y.

1974-01-01

Describes how astrophysics can be a do-it-yourself project within a school boy's budget and background, by giving detailed instruction on equipment construction. In addition, this article describes many experiments to undertake, with the equipment, such as determining color temperature, star spectra, chemical composition and others. (BR)

Action starring narratives and events: Structure and inference in visual narrative comprehension

PubMed Central

Cohn, Neil; Wittenberg, Eva

2015-01-01

Studies of discourse have long placed focus on the inference generated by information that is not overtly expressed, and theories of visual narrative comprehension similarly focused on the inference generated between juxtaposed panels. Within the visual language of comics, star-shaped “flashes” commonly signify impacts, but can be enlarged to the size of a whole panel that can omit all other representational information. These “action star” panels depict a narrative culmination (a “Peak”), but have content which readers must infer, thereby posing a challenge to theories of inference generation in visual narratives that focus only on the semantic changes between juxtaposed images. This paper shows that action stars demand more inference than depicted events, and that they are more coherent in narrative sequences than scrambled sequences (Experiment 1). In addition, action stars play a felicitous narrative role in the sequence (Experiment 2). Together, these results suggest that visual narratives use conventionalized depictions that demand the generation of inferences while retaining narrative coherence of a visual sequence. PMID:26709362

The Nuclear Symmetry Energy and the Mass-Radius Relation of Neutron Stars

NASA Astrophysics Data System (ADS)

Lattimer, James

2017-01-01

The assumptions that i) neutron stars have hadronic crusts, ii) the equation of state is causal, iii) GR is the correct theory of gravity, and iv) their largest observed mass is 2 solar masses, when coupled with recent results from nuclear experiment and theoretical studies of neutron matter, generate powerful constraints on their structure. These include restriction of the radii of typical neutron stars to the range 11-13 km, as well as significant correlations among their masses, compactnesses, moments of inertia, binding energies, and tidal deformabilities. In addition, properties of quark matter, including the location and magnitude of the quark-hadron phase transition, can also be limited. The implications of recent and forthcoming experiments, such as those pertaining to the neutron skin thickness and astrophysical measurements of various structural properties is discussed. For the latter, emphasis is placed on pulsar timing, X-ray observations, supernova neutrino detections, and gravitational waves from mergers involving neutron stars. Supported in part by the US DOE grant DE-AC02-87ER40317.

First ultraviolet spectropolarimetry of Be stars from the Wisconsin Ultraviolet Photo-Polarimeter Experiment

NASA Technical Reports Server (NTRS)

Bjorkman, K. S.; Nordsieck, K. H.; Code, A. D.; Anderson, C. M.; Babler, B. L.; Clayton, G. C.; Magalhaes, A. M.; Meade, M. R.; Nook, M. A.; Schulte-Ladbeck, R. E.

1991-01-01

The first UV spectropolarimetric observations of Be stars are presented. They were obtained with the Wisconsin Ultraviolet Photo-Polarimeter Experiment (WUPPE) aboard the Astro-1 mission. WUPPE data on the Be stars Zeta Tau and Pi Aqr, along with near-simultaneous optical data obtained at the Pine Bluff Observatory (PBO). Combined WUPPE and PBO data give polarization as a function of wavelength across a very broad spectral region, from 1400 to 7600 A. Existing Be star models predicted increasing polarization toward shorter wavelengths in the UV, but this is not supported by the WUPPE observations. Instead, the observations show a constant or slightly declining continuum polarization shortward of the Balmer jump, and broad UV polarization dips around 1700 and 1900 A, which may be a result of Fe-line-attenuation effects on the polarized flux. Supporting evidence for this conclusion comes from the optical data, in which decreases in polarization across Fe II lines in Zeta Tau were discovered.

STAR Online Framework: from Metadata Collection to Event Analysis and System Control

NASA Astrophysics Data System (ADS)

Arkhipkin, D.; Lauret, J.

2015-05-01

In preparation for the new era of RHIC running (RHIC-II upgrades and possibly, the eRHIC era), the STAR experiment is expanding its modular Message Interface and Reliable Architecture framework (MIRA). MIRA allowed STAR to integrate meta-data collection, monitoring, and online QA components in a very agile and efficient manner using a messaging infrastructure approach. In this paper, we briefly summarize our past achievements, provide an overview of the recent development activities focused on messaging patterns and describe our experience with the complex event processor (CEP) recently integrated into the MIRA framework. CEP was used in the recent RHIC Run 14, which provided practical use cases. Finally, we present our requirements and expectations for the planned expansion of our systems, which will allow our framework to acquire features typically associated with Detector Control Systems. Special attention is given to aspects related to latency, scalability and interoperability within heterogeneous set of services, various data and meta-data acquisition components coexisting in STAR online domain.

All things White Dwarf: The State of Stellar Forensics at the University of Texas and Sandia National Laboratories

NASA Astrophysics Data System (ADS)

Winget, Donald

2011-10-01

Astronomy has always been considered an observational science, in contrast with other experimental sciences like physics, chemistry, biology, and geology. This is because it has not been possible to perform experiments on the objects we observe. This situation has changed in a way that is transformational. We are now able to make macroscopic bits of star stuff in the lab: plasmas created under conditions that are the same as the plasmas in stars. Although laboratory astrophysics has long been an important part of astronomical research, what has changed is the ability to produce large enough chunks of a star that we can make measurements and perform experiments. In this way, astronomy joins her sister sciences in becoming an experimental science as well as an observational one. I will describe how this came about, the technology behind it, and the results of recent laboratory experiments. Most importantly, we will discuss how this will change our understanding of the universe and its contents. This work will shed new light on our recent discoveries involving McDonald Observatory: planets around white dwarf stars, massive carbon/oxygen variable white dwarf stars, and white dwarf-white dwarf binaries -- including one detached double eclipsing system with an orbital period of 12 minutes. We should measure the rate of change of the orbital period in this system within a year and we expect it to be the highest S/N source of gravitational radiation, easily detectable with LISA or similar approaches.

Dynamics of gas-thrust bearings

NASA Technical Reports Server (NTRS)

Stiffler, A. K.; Tapia, R. R.

1978-01-01

Computer program calculates load coefficients, up to third harmonic, for hydrostatic gas thrust bearings. Program is useful in identification of industrial situations where gas-thrust bearings have potential applications.

Applicaton of the Calculating Formula for Mean Neutron Exposure on Barium stars

NASA Astrophysics Data System (ADS)

Zhang, F. H.; Zhang, L.; Cui, W. Y.; Zhang, B.

2017-11-01

Latest studies have shown that, in the s-process nucleosynthesis model for the low-mass asymptotic giant branch (AGB) star with (13C) pocket radiative burning during the interpulse period, the distribution of neutron exposures in the nucleosynthesis region can be regarded as an exponential function, and the relation between the mean neutron exposure (τ0) and the model parameters is (τ0} = - Δ τ/ln [q/(1 - r + q)]), in which (Δ τ) is the exposure value of each neutron irradiation, (r) is the overlap factor, and (q) is the mass ratio of the (13C) shell to the He intershell. In this paper the formula is applied to 26 samples of barium stars to test its reliability, and furthermore the neutron exposure nature in the AGB companion stars of 26 barium stars are analyzed. The results show that, the formula is reliable; in the AGB companion stars of 26 barium stars, at least 8 stars definitely have and 12 stars are highly likely to have exponential distribution of neutron exposures, while 4 stars tend to experience single neutron exposure; most of the AGB companion stars may have experienced fewer times of neutron irradiations before the element abundance distribution of the s-process comes to asymptotic condition.