Sample records for take-off vertical landing

  1. Viability of Cross-Flow Fan for Vertical Take-Off and Landing Aircraft

    DTIC Science & Technology

    2012-06-01

    NAVAL POSTGRADUATE SCHOOL MONTEREY, CALIFORNIA THESIS Approved for public release; distribution is unlimited VIABILITY OF CROSS...FLOW FAN FOR VERTICAL TAKE-OFF AND LANDING AIRCRAFT by Christopher T. Delagrange June 2012 Thesis Advisor: Garth V. Hobson Second...AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE Viability of Cross-Flow Fan for Vertical Take-Off and Landing Aircraft 5. FUNDING

  2. Requirements report for SSTO vertical take-off and horizontal landing vehicle

    NASA Technical Reports Server (NTRS)

    Greenberg, H. S.

    1994-01-01

    This document describes the detailed design requirements and design criteria to support Structures/TPS Technology development for SSTO winged vehicle configurations that use vertical take-off and horizontal landing and delivers 25,000 lb payloads to a 220 nm circular orbit at an inclination of 51.6 degrees or 40,000 lb payloads to a 150 nm circular orbit at a 28.5 degree inclination.

  3. Requirements report for SSTO vertical take-off/horizontal landing vehicle

    NASA Technical Reports Server (NTRS)

    Greenberg, H. S.

    1994-01-01

    This document describes the detailed design requirements and design criteria to support Structures/TPS Technology development for SSTO winged vehicle configurations that use vertical take-off and horizontal landing and deliver 25,000 lb payloads to a 220 nm circular orbit at an inclination of 51.6 degrees or 40,000 lb payloads to a 150 nm circular orbit at a 28.5 degree of inclination. This document will be updated on a timely basis as informatIon becomes available throughout the project.

  4. Requirements report for SSTO vertical take-off/horizontal landing vehicle

    NASA Astrophysics Data System (ADS)

    Greenberg, H. S.

    1994-07-01

    This document describes the detailed design requirements and design criteria to support Structures/TPS Technology development for SSTO winged vehicle configurations that use vertical take-off and horizontal landing and deliver 25,000 lb payloads to a 220 nm circular orbit at an inclination of 51.6 degrees or 40,000 lb payloads to a 150 nm circular orbit at a 28.5 degree of inclination. This document will be updated on a timely basis as informatIon becomes available throughout the project.

  5. Flight Investigation of the Stability and Control Characteristics of a 1/4-Scale Model of a Tilt-Wing Vertical-Take-Off-and-Landing Aircraft

    NASA Technical Reports Server (NTRS)

    Tosti, Louis P.

    1959-01-01

    An experimental investigation has been conducted to determine the dynamic stability and control characteristics of a tilt-wing vertical-take-off-and-landing aircraft with the use of a remotely controlled 1/4-scale free-flight model. The model had two propellers with hinged (flapping) blades mounted on the wing which could be tilted up to an incidence angle of nearly 90 deg for vertical take-off and landing. The investigation consisted of hovering flights in still air, vertical take-offs and landings, and slow constant-altitude transitions from hovering to forward flight. The stability and control characteristics of the model were generally satisfactory except for the following characteristics. In hovering flight, the model had an unstable pitching oscillation of relatively long period which the pilots were able to control without artificial stabilization but which could not be considered entirely satisfactory. At very low speeds and angles of wing incidence on the order of 70 deg, the model experienced large nose-up pitching moments which severely limited the allowable center-of-gravity range.

  6. Development of a Cross-Flow Fan Rotor for Vertical Take-Off and Landing Aircraft

    DTIC Science & Technology

    2013-06-01

    ANSYS CFX , along with the commercial computer-aided design software SolidWorks, was used to model and perform a parametric study on the number of rotor...the results found using ANSYS CFX . The experimental and analytical models were successfully compared at speeds ranging from 4,000 to 7,000 RPM...will make vertical take-off possible. The commercial computational fluid dynamics software ANSYS CFX , along with the commercial computer-aided design

  7. AVALON: definition and modeling of a vertical takeoff and landing UAV

    NASA Astrophysics Data System (ADS)

    Silva, N. B. F.; Marconato, E. A.; Branco, K. R. L. J. C.

    2015-09-01

    Unmanned Aerial Vehicles (UAVs) have been used in numerous applications, like remote sensing, precision agriculture and atmospheric data monitoring. Vertical takeoff and landing (VTOL) is a modality of these aircrafts, which are capable of taking off and landing vertically, like a helicopter. This paper presents the definition and modeling of a fixed- wing VTOL, named AVALON (Autonomous VerticAL takeOff and laNding), which has the advantages of traditional aircrafts with improved performance and can take off and land in small areas. The principles of small UAVs development were followed to achieve a better design and to increase the range of applications for this VTOL. Therefore, we present the design model of AVALON validated in a flight simulator and the results show its validity as a physical option for an UAV platform.

  8. Take-Off and Landing Characteristics of a 0.13-Scale Model of the Convair XFY-1 Vertically Rising Airplane in Steady Winds, TED No. NACA DE 368

    NASA Technical Reports Server (NTRS)

    Schade, Robert O.; Smith, Charles C., Jr.; Lovell, P. M., Jr.

    1954-01-01

    An experimental investigation has been conducted to determine the stability and control characteristics of a 0.13-scale free-flight model of the Convair XFY-1 airplane during take-offs and landings in steady winds. The tests indicated that take-offs in headwinds up to at least 20 knots (full scale) will be fairly easy to perform although the airplane may be blown downstream as much as 3 spans before a trim condition can be established. The distance that the airplane will be blown down-stream can be reduced by restraining the upwind landing gear until the instant of take-off. The tests also indicated that spot landings in headwinds up to at least 30 knots (full scale) and in crosswinds up to at least 20 knots (full scale) can be accomplished with reasonable accuracy although, during the landing approach, there will probably be an undesirable nosing-up tendency caused by ground effect and by the change in angle of attack resulting from vertical descent. Some form of arresting gear will probably be required to prevent the airplane from rolling downwind or tipping over after contact. This rolling and tipping can be prevented by a snubbing line attached to the tip of the upwind' wing or tail or by an arresting gear consisting of a wire mesh on the ground and hooks on the landing gear to engage the mesh.

  9. Ground reaction forces and knee mechanics in the weight acceptance phase of a dance leap take-off and landing.

    PubMed

    Kulig, Kornelia; Fietzer, Abbigail L; Popovich, John M

    2011-01-01

    Aesthetic constraints allow dancers fewer technique modifications than other athletes to negotiate the demands of leaping. We examined vertical ground reaction force and knee mechanics during a saut de chat performed by healthy dancers. It was hypothesized that vertical ground reaction force during landing would exceed that of take-off, resulting in greater knee extensor moments and greater knee angular stiffness. Twelve dancers (six males, six females; age 18.9 ± 1.2 years, mass 59.2 ± 9.5 kg, height 1.68 ± 0.08 m, dance training 8.9 ± 5.1 years) with no history of low back pain or lower extremity pathology participated in the study. Saut de chat data were captured using an eight-camera Vicon system and AMTI force platforms. Peak ground reaction force was 26% greater during the landing phase, but did not result in increased peak knee extensor moments. Taking into account the 67% greater knee angular displacement during landing, this resulted in less knee angular stiffness during landing. In conclusion, landing was accomplished with less knee angular stiffness despite the greater peak ground reaction force. A link between decreased joint angular stiffness and increased soft tissue injury risk has been proposed elsewhere; therefore, landing from a saut de chat may be more injurious to the knee soft tissue than take-off.

  10. Stresses developed in seaplanes while taking off and landing

    NASA Technical Reports Server (NTRS)

    Verduzio, Rudolfo

    1932-01-01

    In the case of seaplanes, the lack of elastic shock absorbers, the presence of which might be quite dangerous, especially in taking off, makes it necessary to give some consideration to the phenomenon of landing. Special consideration must be given the process of taking off, since even moderately rough water may develop rather large stresses. The purpose of this communication is to show what has been accomplished in Italy and other countries and to draw a few useful conclusions.

  11. Measurement of the Errors of Service Altimeter Installations During Landing-Approach and Take-Off Operations

    NASA Technical Reports Server (NTRS)

    Gracey, William; Jewel, Joseph W., Jr.; Carpenter, Gene T.

    1960-01-01

    The overall errors of the service altimeter installations of a variety of civil transport, military, and general-aviation airplanes have been experimentally determined during normal landing-approach and take-off operations. The average height above the runway at which the data were obtained was about 280 feet for the landings and about 440 feet for the take-offs. An analysis of the data obtained from 196 airplanes during 415 landing approaches and from 70 airplanes during 152 take-offs showed that: 1. The overall error of the altimeter installations in the landing- approach condition had a probable value (50 percent probability) of +/- 36 feet and a maximum probable value (99.7 percent probability) of +/- 159 feet with a bias of +10 feet. 2. The overall error in the take-off condition had a probable value of +/- 47 feet and a maximum probable value of +/- 207 feet with a bias of -33 feet. 3. The overall errors of the military airplanes were generally larger than those of the civil transports in both the landing-approach and take-off conditions. In the landing-approach condition the probable error and the maximum probable error of the military airplanes were +/- 43 and +/- 189 feet, respectively, with a bias of +15 feet, whereas those for the civil transports were +/- 22 and +/- 96 feet, respectively, with a bias of +1 foot. 4. The bias values of the error distributions (+10 feet for the landings and -33 feet for the take-offs) appear to represent a measure of the hysteresis characteristics (after effect and recovery) and friction of the instrument and the pressure lag of the tubing-instrument system.

  12. Vertical Take-Off and Landing Vehicle with Increased Cruise Efficiency

    NASA Technical Reports Server (NTRS)

    Fredericks, William J. (Inventor); Moore, Mark D. (Inventor); Busan, Ronald C. (Inventor); Johns, Zachary R. (Inventor); Langford, William M. (Inventor); Rothhaar, Paul M. (Inventor); North, David D. (Inventor); Laws, Christopher T. (Inventor); Hodges, William T. (Inventor); Webb, Sandy R. (Inventor)

    2016-01-01

    Systems, methods, and devices are provided that combine an advance vehicle configuration, such as an advanced aircraft configuration, with the infusion of electric propulsion, thereby enabling a four times increase in range and endurance while maintaining a full vertical takeoff and landing ("VTOL") and hover capability for the vehicle. Embodiments may provide vehicles with both VTOL and cruise efficient capabilities without the use of ground infrastructure. An embodiment vehicle may comprise a wing configured to tilt through a range of motion, a first series of electric motors coupled to the wing and each configured to drive an associated wing propeller, a tail configured to tilt through the range of motion, a second series of electric motors coupled to the tail and each configured to drive an associated tail propeller, and an electric propulsion system connected to the first series of electric motors and the second series of electric motors.

  13. Dynamic load indicators for take-off-landing sequence in blocks and attacks of elite female volleyball players.

    PubMed

    Kabaciński, Jarosław; Dworak, Lechosław Bogdan; Murawa, Michał; Rzepnicka, Agata

    2016-01-01

    Dynamic loads during landings determined by the ground reaction forces (GRFs) may elaborate internal loads and increase the risk of overload knee injuries as a result of performing volleyball jumps many times. The study dealt with a biomechanical assessment of dynamic load indicators in female volleyball players for the motion sequence of take-off-landing in blocks and attacks. Twelve professional female volleyball players participated in the study. Blocks and attacks were filmed by two cameras. GRFs vs. time graphs were recorded with the use of a force platform. Values of dynamic load indicators in terms of the relations of peak of vertical component of GRF, build-up index of this force (BIF), and power output (P) during landing to the vGRF, BIF and P during take-off (L/T) were calculated. The statistically significant ( p < 0.05) highest values of L/T indicators were found for back row attack spikes: 2.4 (vGRF), 12.2 (BIF) and 3.1 (P). In the case of blocks, slide attack spikes and attack line spikes, results of these variables were in range: 1.8÷2.1, 5.9÷7.6 and 2.1÷2.9, respectively. The reduction of GRFs during landings contributes to decreasing the level of the load indicators L/T which should minimize the incidence of anterior cruciate ligament and patellar tendon injuries in female volleyball players.

  14. A Mathematical Model for Vertical Attitude Takeoff and Landing (VATOL) Aircraft Simulation. Volume 1; Model Description Application

    NASA Technical Reports Server (NTRS)

    Fortenbaugh, R. L.

    1980-01-01

    A mathematical model of a high performance airplane capable of vertical attitude takeoff and landing (VATOL) was developed. An off line digital simulation program incorporating this model was developed to provide trim conditions and dynamic check runs for the piloted simulation studies and support dynamic analyses of proposed VATOL configuration and flight control concepts. Development details for the various simulation component models and the application of the off line simulation program, Vertical Attitude Take-Off and Landing Simulation (VATLAS), to develop a baseline control system for the Vought SF-121 VATOL airplane concept are described.

  15. The UAV take-off and landing system used for small areas of mobile vehicles

    NASA Astrophysics Data System (ADS)

    Ren, Tian-Yu; Duanmu, Qing-Duo; Wu, Bo-Qi

    2018-03-01

    In order to realize an UAV formation cluster system based on the current GPS and the fault and insufficiency of Beidou integrated navigation system in strong jamming environment. Due to the impact of the compass on the plane crash, navigation system error caused by the mobile area to help reduce the need for large landing sites and not in the small fast moving area to achieve the reality of the landing. By using Strapdown inertial and all-optical system to form Composite UAV flight control system, the photoelectric composite strapdown inertial coupling is realized, and through the laser and microwave telemetry link compound communication mechanism, using all-optical strapdown inertial and visual navigation system to solve the deviation of take-off and landing caused by electromagnetic interference, all-optical bidirectional data link realizes two-way position correction of landing site and aircraft, thus achieves the accurate recovery of UAV formation cluster in the mobile narrow area which the traditional navigation system can't realize. This system is a set of efficient unmanned aerial vehicle Group Take-off/descending system, which is suitable for many tasks, and not only realizes the reliable continuous navigation under the complex electromagnetic interference environment, moreover, the intelligent flight and Take-off and landing of unmanned aerial vehicles relative to the fast moving and small recovery sites in complex electromagnetic interference environment can not only improve the safe operation rate of unmanned aerial vehicle, but also guarantee the operation safety of the aircraft, and the more has important social value for the application foreground of the aircraft.

  16. Force-Test Investigation of the Stability and Control Characteristics of a 1/4-Scale Model of a Tilt-Wing Vertical-Take-Off-and-Landing Aircraft

    NASA Technical Reports Server (NTRS)

    Newsom, William A., Jr.; Tosti, Louis P.

    1959-01-01

    A wind-tunnel investigation has been made to determine the aerodynamic characteristics of a 1/4-scale model of a tilt-wing vertical-take-off-and-landing aircraft. The model had two 3-blade single-rotation propellers with hinged (flapping) blades mounted on the wing, which could be tilted from an incidence of 4 deg for forward flight to 86 deg for hovering flight. The investigation included measurements of both the longitudinal and lateral stability and control characteristics in both the normal forward flight and the transition ranges. Tests in the forward-flight condition were made for several values of thrust coefficient, and tests in the transition condition were made at several values of wing incidence with the power varied to cover a range of flight conditions from forward-acceleration (or climb) conditions to deceleration (or descent) conditions The control effectiveness of the all-movable horizontal tail, the ailerons and the differential propeller pitch control was also determined. The data are presented without analysis.

  17. Low Noise Cruise Efficient Short Take-Off and Landing Transport Vehicle Study

    NASA Technical Reports Server (NTRS)

    Kim, Hyun D.; Berton, Jeffrey J.; Jones, Scott M.

    2007-01-01

    The saturation of the airspace around current airports combined with increasingly stringent community noise limits represents a serious impediment to growth in world aviation travel. Breakthrough concepts that both increase throughput and reduce noise impacts are required to enable growth in aviation markets. Concepts with a 25 year horizon must facilitate a 4x increase in air travel while simultaneously meeting community noise constraints. Attacking these horizon issues holistically is the concept study of a Cruise Efficient Short Take-Off and Landing (CESTOL) high subsonic transport under the NASA's Revolutionary Systems Concepts for Aeronautics (RSCA) project. The concept is a high-lift capable airframe with a partially embedded distributed propulsion system that takes a synergistic approach in propulsion-airframe-integration (PAI) by fully integrating the airframe and propulsion systems to achieve the benefits of both low-noise short take-off and landing (STOL) operations and efficient high speed cruise. This paper presents a summary of the recent study of a distributed propulsion/airframe configuration that provides low-noise STOL operation to enable 24-hour use of the untapped regional and city center airports to increase the capacity of the overall airspace while still maintaining efficient high subsonic cruise flight capability.

  18. Strapdown system redundancy management flight demonstration. [vertical takeoff and landing aircraft

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The suitability of strapdown inertial systems in providing highly reliable short-term navigation for vertical take-off and landing (VTOL) aircraft operating in an intra-urban setting under all-weather conditions was assessed. A preliminary design configuration of a skewed sensor inertial reference system employing a redundancy management concept to achieve fail-operational, fail-operational performance, was developed.

  19. Analysis of the effects of boundary-layer control in the take-off and power-off landing performance characteristics of a liaison type of airplane

    NASA Technical Reports Server (NTRS)

    Horton, Elmer A; Loftin, Laurence K; Racisz, Stanley F; Quinn, John

    1951-01-01

    A performance analysis has been made to determine whether boundary-layer control by suction might reduce the minimum take-off and landing distances of a four-place or five-place airplane or a liaison type of airplane below those obtainable with conventional high-lift devices. The airplane was assumed to have a cruise duration of 5 hours at 60-percent power and to be operating from airstrips having a ground friction coefficient of 0.2 or a combined ground and braking coefficient of 0.4. The payload was fixed at 1500 pounds, the wing span was varied from 25 to 100 feet, the aspect ratio was varied from 5 to 15, and the power was varied from 300 to 1300 horsepower. Maximum lift coefficients of 5.0 and 2.8 were assumed for the airplanes with and without boundary-layer-control --equipment weight was included. The effects of the boundary-layer control on total take-off distance, total power-off landing distance, landing and take-off ground run, stalling speed, sinking speed, and gliding speed were determined.

  20. Magnetic levitation assisted aircraft take-off and landing (feasibility study - GABRIEL concept)

    NASA Astrophysics Data System (ADS)

    Rohacs, Daniel; Rohacs, Jozsef

    2016-08-01

    The Technology Roadmap 2013 developed by the International Air Transport Association envisions the option of flying without an undercarriage to be in operation by 2032. Preliminary investigations clearly indicate that magnetic levitation technology (MagLev) might be an appealing solution to assist the aircraft take-off and landing. The EU supported research project, abbreviated as GABRIEL, was dealing with (i) the concept development, (ii) the identification, evaluation and selection of the deployable magnetic levitation technology, (iii) the definition of the core system elements (including the required aircraft modifications, the ground-based system and airport elements, and the rendezvous control system), (iv) the analysis of the safety and security aspects, (v) the concept validation and (vi) the estimation of the proposed concept impact in terms of aircraft weight, noise, emission, cost-benefit). All results introduced here are compared to a medium size hypothetic passenger aircraft (identical with an Airbus A320). This paper gives a systematic overview of (i) the applied methods, (ii) the investigation of the possible use of magnetic levitation technology to assist the commercial aircraft take-off and landing processes and (iii) the demonstrations, validations showing the feasibility of the radically new concept. All major results are outlined.

  1. Validation of an Active Gear, Flexible Aircraft Take-off and Landing analysis (AGFATL)

    NASA Technical Reports Server (NTRS)

    Mcgehee, J. R.

    1984-01-01

    The results of an analytical investigation using a computer program for active gear, flexible aircraft take off and landing analysis (AGFATL) are compared with experimental data from shaker tests, drop tests, and simulated landing tests to validate the AGFATL computer program. Comparison of experimental and analytical responses for both passive and active gears indicates good agreement for shaker tests and drop tests. For the simulated landing tests, the passive and active gears were influenced by large strut binding friction forces. The inclusion of these undefined forces in the analytical simulations was difficult, and consequently only fair to good agreement was obtained. An assessment of the results from the investigation indicates that the AGFATL computer program is a valid tool for the study and initial design of series hydraulic active control landing gear systems.

  2. Taxiing, Take-Off, and Landing Simulation of the High Speed Civil Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Reaves, Mercedes C.; Horta, Lucas G.

    1999-01-01

    The aircraft industry jointly with NASA is studying enabling technologies for higher speed, longer range aircraft configurations. Higher speeds, higher temperatures, and aerodynamics are driving these newer aircraft configurations towards long, slender, flexible fuselages. Aircraft response during ground operations, although often overlooked, is a concern due to the increased fuselage flexibility. This paper discusses modeling and simulation of the High Speed Civil Transport aircraft during taxiing, take-off, and landing. Finite element models of the airframe for various configurations are used and combined with nonlinear landing gear models to provide a simulation tool to study responses to different ground input conditions. A commercial computer simulation program is used to numerically integrate the equations of motion and to compute estimates of the responses using an existing runway profile. Results show aircraft responses exceeding safe acceptable human response levels.

  3. Adaptive Data-based Predictive Control for Short Take-off and Landing (STOL) Aircraft

    NASA Technical Reports Server (NTRS)

    Barlow, Jonathan Spencer; Acosta, Diana Michelle; Phan, Minh Q.

    2010-01-01

    Data-based Predictive Control is an emerging control method that stems from Model Predictive Control (MPC). MPC computes current control action based on a prediction of the system output a number of time steps into the future and is generally derived from a known model of the system. Data-based predictive control has the advantage of deriving predictive models and controller gains from input-output data. Thus, a controller can be designed from the outputs of complex simulation code or a physical system where no explicit model exists. If the output data happens to be corrupted by periodic disturbances, the designed controller will also have the built-in ability to reject these disturbances without the need to know them. When data-based predictive control is implemented online, it becomes a version of adaptive control. The characteristics of adaptive data-based predictive control are particularly appropriate for the control of nonlinear and time-varying systems, such as Short Take-off and Landing (STOL) aircraft. STOL is a capability of interest to NASA because conceptual Cruise Efficient Short Take-off and Landing (CESTOL) transport aircraft offer the ability to reduce congestion in the terminal area by utilizing existing shorter runways at airports, as well as to lower community noise by flying steep approach and climb-out patterns that reduce the noise footprint of the aircraft. In this study, adaptive data-based predictive control is implemented as an integrated flight-propulsion controller for the outer-loop control of a CESTOL-type aircraft. Results show that the controller successfully tracks velocity while attempting to maintain a constant flight path angle, using longitudinal command, thrust and flap setting as the control inputs.

  4. Comparison of pre-contact joint kinematics and vertical impulse between vertical jump landings and step-off landings from equal heights.

    PubMed

    Harry, John R; Freedman Silvernail, Julia; Mercer, John A; Dufek, Janet S

    2017-12-01

    Although impact phase differences between vertical jump landings (VJL) and step-off landings (STL) may be related to task-specific pre-contact strategies, pre-contact mechanics are rarely examined. Thus, pre-contact kinematics and vertical ground reaction force (vGRF) impulse were examined between VJL and STL. Ten health adults (20.9 ± 1.6 yrs; 167.8 ± 4.2 cm; 68.5 ± 7.15 kg) performed 15 VJL and 15 STL from equal heights. Limb (lead; trail) by task (VJL; STL) ANOVAs (α = 0.05) compared hip, knee, and ankle joint angles 150 ms pre-contact, 100 ms pre-contact, 50 ms pre-contact, and at ground contact. Joint angular displacement was also evaluated between 150 ms pre-contact and ground contact. vGRF impulse was compared during the loading (ground contact to peak vGRF) and attenuation (peak vGRF to end of impact) phases. Greater hip flexion angles occurred during STL versus VJL at each event except 150 ms pre-contact (p ≤ .004). Trail limb knee flexion angles were greater at each event when compared to the lead limb during STL (p ≤ .019). Greater trail limb knee flexion angles occurred during STL versus VJL at all four events (p ≤ .018), while greater plantarflexion angles occurred at all four events during VJL versus STL (p ≤ .034). During STL, greater trail limb plantarflexion angles were detected at each event versus the lead limb (p < .001). Lesser hip, lead and trail limb knee displacement occurred during STL versus VJL (p < .05). Greater vGRF impulse was detected during the loading phase of VJL (<.001), while greater vGRF impulse occurred during the attenuation phase of STL (p = .025). These tasks are characterized by distinct pre-contact kinematic strategies and post-contact kinetics. The task utilized in practice should reflect the requirements of the population of interest. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Smooth-Water Landing Stability and Rough-Water Landing and Take-Off Behavior of a 1/13-Scale Model of the Consolidated Vultee Skate 7 Seaplane, TED No. NACA DE 338

    NASA Technical Reports Server (NTRS)

    McKann, Robert F.; Coffee, Claude W.; Arabian, Donald D.

    1949-01-01

    A model of the Consolidated Vultee Aircraft Corporation Skate 7 seaplane was tested in Langley tank no. 2. Presented without discussion in this paper are landing stability in smooth water, maximum normal accelerations occurring during rough-water landings, and take-off behavior in waves.

  6. Aerodynamics of a beetle in take-off flights

    NASA Astrophysics Data System (ADS)

    Lee, Boogeon; Park, Hyungmin; Kim, Sun-Tae

    2015-11-01

    In the present study, we investigate the aerodynamics of a beetle in its take-off flights based on the three-dimensional kinematics of inner (hindwing) and outer (elytron) wings, and body postures, which are measured with three high-speed cameras at 2000 fps. To track the highly deformable wing motions, we distribute 21 morphological markers and use the modified direct linear transform algorithm for the reconstruction of measured wing motions. To realize different take-off conditions, we consider two types of take-off flights; that is, one is the take-off from a flat ground and the other is from a vertical rod mimicking a branch of a tree. It is first found that the elytron which is flapped passively due to the motion of hindwing also has non-negligible wing-kinematic parameters. With the ground, the flapping amplitude of elytron is reduced and the hindwing changes its flapping angular velocity during up and downstrokes. On the other hand, the angle of attack on the elytron and hindwing increases and decreases, respectively, due to the ground. These changes in the wing motion are critically related to the aerodynamic force generation, which will be discussed in detail. Supported by the grant to Bio-Mimetic Robot Research Center funded by Defense Acquisition Program Administration (UD130070ID).

  7. Static internal performance of ventral and rear nozzle concepts for short-takeoff and vertical-landing aircraft

    NASA Technical Reports Server (NTRS)

    Re, Richard J.; Carson, George T., Jr.

    1991-01-01

    The internal performance of two exhaust system concepts applicable to single-engine short-take-off and vertical-landing tactical fighter configurations was investigated. These concepts involved blocking (or partially blocking) tailpipe flow to the rear (cruise) nozzle and diverting it through an opening to a ventral nozzle exit for vertical thrust. A set of variable angle vanes at the ventral nozzle exit were used to vary ventral nozzle thrust angle between 45 and 110 deg relative to the positive axial force direction. In the vertical flight mode the rear nozzle (or tailpipe flow to it) was completely blocked. In the transition flight mode flow in the tailpipe was split between the rear and ventral nozzles and the flow was vectored at both exits for aircraft control purposes through this flight regime. In the cruise flight mode the ventral nozzle was sealed and all flow exited through the rear nozzle.

  8. Behaviour of coconut mites preceding take-off to passive aerial dispersal.

    PubMed

    Melo, J W S; Lima, D B; Sabelis, M W; Pallini, A; Gondim, M G C

    2014-12-01

    For more than three decades the coconut mite Aceria guerreronis Keifer is one of the most important pests of coconut palms and has recently spread to many coconut production areas worldwide. Colonization of coconut palms is thought to arise from mites dispersing aerially after take-off from other plants within the same plantation or other plantations. The underlying dispersal behaviour of the mite at take-off, in the airborne state and after landing is largely unknown and this is essential to understand how they spread from tree to tree. In this article we studied whether take-off to aerial dispersal of coconut mites is preceded by characteristic behaviour, whether there is a correlation between the body position preceding aerial dispersal and the direction of the wind, and whether the substrate (outer surface of coconut bracts or epidermis) and the wind speed matter to the decision to take-off. We found that take-off can sometimes be preceded by a raised body stance, but more frequently take-off occurs while the mite is walking or resting on its substrate. Coconut mites that become airborne assumed a body stance that had no relation to the wind direction. Take-off was suppressed on a substrate providing food to coconut mites, but occurred significantly more frequently on the outer surface of coconut bracts than on the surface of the fruit. For both substrates, take-off frequency increased with wind speed. We conclude that coconut mites have at least some degree of control over take-off for aerial dispersal and that there is as yet no reason to infer that a raised body stance is necessary to become airborne.

  9. Optimum take-off angle in the long jump.

    PubMed

    Linthorne, Nicholas P; Guzman, Maurice S; Bridgett, Lisa A

    2005-07-01

    In this study, we found that the optimum take-off angle for a long jumper may be predicted by combining the equation for the range of a projectile in free flight with the measured relations between take-off speed, take-off height and take-off angle for the athlete. The prediction method was evaluated using video measurements of three experienced male long jumpers who performed maximum-effort jumps over a wide range of take-off angles. To produce low take-off angles the athletes used a long and fast run-up, whereas higher take-off angles were produced using a progressively shorter and slower run-up. For all three athletes, the take-off speed decreased and the take-off height increased as the athlete jumped with a higher take-off angle. The calculated optimum take-off angles were in good agreement with the athletes' competition take-off angles.

  10. A mathematical model for Vertical Attitude Takeoff and Landing (VATOL) aircraft simulation. Volume 3: User's manual for VATOL simulation program

    NASA Technical Reports Server (NTRS)

    Fortenbaugh, R. L.

    1980-01-01

    Instructions for using Vertical Attitude Takeoff and Landing Aircraft Simulation (VATLAS), the digital simulation program for application to vertical attitude takeoff and landing (VATOL) aircraft developed for installation on the NASA Ames CDC 7600 computer system are described. The framework for VATLAS is the Off-Line Simulation (OLSIM) routine. The OLSIM routine provides a flexible framework and standardized modules which facilitate the development of off-line aircraft simulations. OLSIM runs under the control of VTOLTH, the main program, which calls the proper modules for executing user specified options. These options include trim, stability derivative calculation, time history generation, and various input-output options.

  11. Performance and technological feasibility of rocket powered HTHL-SSTO with take-off assist (aerospace plane/ekranoplane)

    NASA Astrophysics Data System (ADS)

    Tomita, Nobuyuki; Nebylov, Alexander V.; Sokolov, Victor V.; Ohkami, Yoshiaki

    It might be said that it is common understanding that rocket-powered single stage to orbit (SSTO) aerospace planes will become feasible with near-term technology as described in [1] (Koelle, D. E. Survey and comparison of winged launch vehicle options, ISTS 94-g-11 V 1994) and [2] (Bekey, I. Why SSTO rocket launch vehicles are now feasible and practical, IAF-94-V.1.524 1994). Among two methods of launching aerospace planes into orbit, vertical take-off (VT) and horizontal take-off (HT), it seems that VT takes the lead from HT [1, 2]. The decision for the X-33 program by NASA, also, seems to favor VT. In retrospect, almost all of the launch vehicles in the past have been VT, mainly because VT solved the problem of exit from atmosphere to space. However, broadening the range of requirements for space transportation systems from military to commercial and unmanned to manned seems to favor the need for HT. In this paper, the authors are going to prove that aerospace plane/ekranoplane system, which is a reusable launch vehicle system based on the HT concept, with ekranoplane as a take-off and possibly, landing assist, could be competitive with the VT concept from both technological and economical view points. Ekranoplane is a wing-in-ground-effect craft (WIG), which moves at a speed of approximately 0.5 M, carrying heavy loads above the sea surface. Combination of high initial velocity and high performance tri-propellant engine for aerospace plane makes it possible to configure an aerospace plane which is competitive with VT. Other specific features of HT in comparison with VT are discussed.

  12. Hot Water Propulsion for Horizontal Rocket Assisted Take-Off Systems for Future Reusable Launch Vehicles

    NASA Astrophysics Data System (ADS)

    Pilz, N.; Adirim, H.; Lo, R.; Schildknecht, A.

    2004-10-01

    Among other concepts, reusable space transportation systems that comprise winged reusable launch vehicles (RLV) with horizontal take-off and horizontal landing (HTHL) are under worldwide investigation, e.g. the respective concepts within ESA's FESTIP-Study (Future European Space Transportation Integration Program) or the HOPPER concept by EADS-ST. The payload of these RLVs could be significantly increased by means of a ground-based take-off assistance system that would accelerate the vehicle along a horizontal track until it reaches the desired speed to ignite its onboard engines for leaving the ground and launching into orbit. This paper illustrates the advantages of horizontal take-off for winged RLVs and provides an overview of launch-assist options for HTHL RLVs. It presents hot water propulsion for ground-based take-off assistance systems for future RLVs as an attractive choice besides magnetic levitation and acceleration (maglev) technology. Finally, preliminary design concepts are presented for a rocket assisted take-off system (RATOS) with hot water propulsion followed by an analysis of its improvement potential.

  13. Flight investigation of a vertical-velocity command system for VTOL aircraft

    NASA Technical Reports Server (NTRS)

    Kelly, J. R.; Niessen, F. R.; Yenni, K. R.; Person, L. H., Jr.

    1977-01-01

    A flight investigation was undertaken to assess the potential benefits afforded by a vertical-velocity command system (VVCS) for VTOL (vertical take-off and landing) aircraft. This augmentation system was conceived primarily as a means of lowering pilot workload during decelerating approaches to a hover and/or landing under category III instrument meteorological conditions. The scope of the investigation included a determination of acceptable system parameters, a visual flight evaluation, and an instrument flight evaluation which employed a 10 deg, decelerating, simulated instrument approach task. The results indicated that the VVCS, which decouples the pitch and vertical degrees of freedom, provides more accurate glide-path tracking and a lower pilot workload than does the unaugmented system.

  14. Conceptual Design of a Vertical Takeoff and Landing Unmanned Aerial Vehicle with 24-HR Endurance

    NASA Technical Reports Server (NTRS)

    Fredericks, William J.

    2010-01-01

    This paper describes a conceptual design study for a vertical takeoff and landing (VTOL) unmanned aerial vehicle (UAV) that is able to carry a 25-lb science payload for 24 hr and is able to land and take off at elevations as high as 15,000 ft without human intervention. In addition to the science payload, this vehicle must be able to carry a satellite communication system, and the vehicle must be able to be transported in a standard full-size pickup truck and assembled by only two operators. This project started with a brainstorming phase to devise possible vehicle configurations that might satisfy the requirements. A down select was performed to select a near-term solution and two advanced vehicle concepts that are better suited to the intent of the mission. Sensitivity analyses were also performed on the requirements and the technology levels to obtain a better understanding of the design space. This study found that within the study assumptions the mission is feasible; the selected concepts are recommended for further development.

  15. Issues related to aircraft take-off plumes in a mesoscale photochemical model.

    PubMed

    Bossioli, Elissavet; Tombrou, Maria; Helmis, Costas; Kurtenbach, Ralf; Wiesen, Peter; Schäfer, Klaus; Dandou, Aggeliki; Varotsos, Kostas V

    2013-07-01

    The physical and chemical characteristics of aircraft plumes at the take-off phase are simulated with the mesoscale CAMx model using the individual plume segment approach, in a highly resolved domain, covering the Athens International Airport. Emission indices during take-off measured at the Athens International Airport are incorporated. Model predictions are compared with in situ point and path-averaged observations (NO, NO₂) downwind of the runway at the ground. The influence of modeling process, dispersion properties and background air composition on the chemical evolution of the aircraft plumes is examined. It is proven that the mixing properties mainly determine the plume dispersion. The initial plume properties become significant for the selection of the appropriate vertical resolution. Besides these factors, the background NOx and O₃ concentration levels control NOx distribution and their conversion to nitrogen reservoir species. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Vertical Landing Aerodynamics of Reusable Rocket Vehicle

    NASA Astrophysics Data System (ADS)

    Nonaka, Satoshi; Nishida, Hiroyuki; Kato, Hiroyuki; Ogawa, Hiroyuki; Inatani, Yoshifumi

    The aerodynamic characteristics of a vertical landing rocket are affected by its engine plume in the landing phase. The influences of interaction of the engine plume with the freestream around the vehicle on the aerodynamic characteristics are studied experimentally aiming to realize safe landing of the vertical landing rocket. The aerodynamic forces and surface pressure distributions are measured using a scaled model of a reusable rocket vehicle in low-speed wind tunnels. The flow field around the vehicle model is visualized using the particle image velocimetry (PIV) method. Results show that the aerodynamic characteristics, such as the drag force and pitching moment, are strongly affected by the change in the base pressure distributions and reattachment of a separation flow around the vehicle.

  17. Estimating Vertical Land Motion in the Chesapeake Bay

    NASA Astrophysics Data System (ADS)

    Houttuijn Bloemendaal, L.; Hensel, P.

    2017-12-01

    This study aimed to provide a modern measurement of subsidence in the Chesapeake Bay region and establish a methodology for measuring vertical land motion using static GPS, a cheaper alternative to InSAR or classical leveling. Vertical land motion in this area is of particular concern because tide gages are showing up to 5 mm/yr of local, relative sea level rise. While a component of this rate is the actual eustatic sea level rise itself, part of the trend may also be vertical land motion, in which subsidence exacerbates the effects of actual changes in sea level. Parts of this region are already experiencing an increase in the frequency and magnitude of near-shore coastal flooding, but the last comprehensive study of vertical land motion in this area was conducted by NOAA in 1974 (Holdahl & Morrison) using repeat leveled lines. More recent measures of vertical land motion can help inform efforts on resilience to sea level rise, such as in the Hampton Roads area. This study used measured GPS-derived vertical heights in conjunction with legacy GPS data to calculate rates of vertical motion at several points in time for a selection of benchmarks scattered throughout the region. Seventeen marks in the stable Piedmont area and in the areas suspected of subsidence in the Coastal Plain were selected for the analysis. Results indicate a significant difference between the rates of vertical motion in the Piedmont and Coastal Plain, with a mean rate of -4.10 mm/yr in the Coastal Plain and 0.15 mm/yr in the Piedmont. The rates indicate particularly severe subsidence at the southern Delmarva Peninsula coast and the Hampton-Roads area, with a mean rate of -6.57 mm/yr in that region. By knowing local rates of subsidence as opposed to sea level change itself, coastal managers may make better informed decisions regarding natural resource use, such as deciding whether or not to reduce subsurface fluid withdrawals or to consider injecting treated water back into the aquifer to slow

  18. A biomechanical analysis of the last stride, touch-down and take-off characteristics of the women's long jump.

    PubMed

    Lees, A; Fowler, N; Derby, D

    1993-08-01

    This study was concerned with the measurement of a selection of performance variables from competitors in the women's long jump final of the World Student Games held in Sheffield, UK in July 1991. Several performances of each of six finalists were recorded on cine-film at 100 Hz. Resulting planar kinematic data were obtained for the last stride, touch-down and take-off. For the analysis, the point of maximum knee flexion was established and this was used to represent the point at which the compression phase had ended. A variety of variables describing the position, velocity and angular changes are presented as descriptive data. In addition, these were used to compute energies on the basis of a whole body model. The data were interpreted on the basis of a technique model of long jumping established from the literature. It was confirmed that take-off velocity was a function of touch-down velocity, and that there was an increase in vertical velocity at the expense of a reduction of horizontal velocity. An attempt was made to identify the mechanisms acting during the touch-down to take-off phase which were responsible for generating vertical velocity. It was concluded that there was evidence for mechanical, biomechanical and muscular mechanisms. The former relates to the generation of vertical velocity by the body riding over the base of support; the second is the elastic re-utilization of energy; and the third is the contribution by concentric muscular contraction.

  19. Tick off to Take off: The Pre-Departure Guide

    ERIC Educational Resources Information Center

    Arthur, Erica

    2009-01-01

    "Tick Off to Take Off (TOTTO)" is an online pre-departure guide for UK undergraduates intending to study abroad. It aims to simplify the application process, centralise information, increase efficiency and improve retention rates. TOTTO responds to the changing climate surrounding study abroad in UK universities and offers one way to…

  20. Investigation of the Effectiveness of Boundary-layer Control by Blowing over a Combination of Sliding and Plain Flaps in Deflecting a Propeller Slipstream Downward for Vertical Take-off

    NASA Technical Reports Server (NTRS)

    Spreemann, Kenneth P; Kuhn, Richard E

    1956-01-01

    An investigation was conducted in order to determine the effectiveness of blowing a jet of air over the flaps of a wing equipped with a 50-percent-chord sliding flap and a 25-percent-chord plain flap in deflecting a propeller slipstream downward for vertical take-off and the results are presented herein. The effects of a leading-edge slat, ground proximity, end plate, and propeller position were also investigated. The tests were conducted in a static-thrust facility at the Langley Aeronautical Laboratory.

  1. Reducing gravity takes the bounce out of running.

    PubMed

    Polet, Delyle T; Schroeder, Ryan T; Bertram, John E A

    2018-02-13

    In gravity below Earth-normal, a person should be able to take higher leaps in running. We asked 10 subjects to run on a treadmill in five levels of simulated reduced gravity and optically tracked centre-of-mass kinematics. Subjects consistently reduced ballistic height compared with running in normal gravity. We explain this trend by considering the vertical take-off velocity (defined as maximum vertical velocity). Energetically optimal gaits should balance the energetic costs of ground-contact collisions (favouring lower take-off velocity), and step frequency penalties such as leg swing work (favouring higher take-off velocity, but less so in reduced gravity). Measured vertical take-off velocity scaled with the square root of gravitational acceleration, following energetic optimality predictions and explaining why ballistic height decreases in lower gravity. The success of work-based costs in predicting this behaviour challenges the notion that gait adaptation in reduced gravity results from an unloading of the stance phase. Only the relationship between take-off velocity and swing cost changes in reduced gravity; the energetic cost of the down-to-up transition for a given vertical take-off velocity does not change with gravity. Because lower gravity allows an elongated swing phase for a given take-off velocity, the motor control system can relax the vertical momentum change in the stance phase, thus reducing ballistic height, without great energetic penalty to leg swing work. Although it may seem counterintuitive, using less 'bouncy' gaits in reduced gravity is a strategy to reduce energetic costs, to which humans seem extremely sensitive. © 2018. Published by The Company of Biologists Ltd.

  2. Vertical Jump Height is more Strongly Associated with Velocity and Work Performed Prior to Take-off

    NASA Technical Reports Server (NTRS)

    Bentley, J. R.; Loehr, J. A.; DeWitt, J. K.; Lee, S. M. C.; English, K. L.; Nash, R. E.; Leach, M. A.; Hagan, R. D.

    2008-01-01

    Vertical jump (VJ) height is commonly used as a measure of athletic capability in strength and power sports. Although VJ has been shown to be a predictor of athletic performance, it is not clear which kinetic ground reaction force (GRF) variables, such as peak force (PF), peak power (PP), peak velocity (PV), total work (TW) or impulse (Imp) are the best correlates. To determine which kinetic variables (PF, PP, PV, TW, and Imp) best correlate with VJ height. Twenty subjects (14 males, 6 females) performed three maximal countermovement VJs on a force platform (Advanced Mechanical Technology, Inc., Watertown, MA, USA). VJ jump height was calculated as the difference between standing reach and the highest reach point measured using a Vertec. PF, PP, PV, TW, and Imp were calculated using the vertical GRF data sampled at 1000 Hz from the lowest point in the countermovement through the concentric portion until take-off. GRF data were normalized to body mass measured using a standard scale (Detecto, Webb City, MO, USA). Correlation coefficients were computed between each GRF variable and VJ height using a Pearson correlation. VJ height (43.4 plus or minus 9.1 cm) was significantly correlated (p less than 0.001) with PF (998 plus or minus 321 N; r=0.51), PP (1997 plus or minus 772 W; r=0.69), PV (2.66 plus or minus 0.40 m (raised dot) s(sup -1); r=0.85), TW (259 plus or minus 93.0 kJ; r=0.82), and Imp (204 plus or minus 51.1 N(raised dot)s; r=0.67). Although all variables were correlated to VJ height, PV and TW were more strongly correlated to VJ height than PF, PP, and Imp. Therefore, since TW is equal to force times displacement, the relative displacement of the center of mass along with the forces applied during the upward movement of the jump are critical determinants of VJ height. PV and TW are key determinants of VJ height, and therefore successful training programs to increase VJ height should focus on rapid movement (PV) and TW by increasing power over time rather

  3. Integrating ecosystem services trade-offs with paddy land-to-dry land decisions: A scenario approach in Erhai Lake Basin, southwest China.

    PubMed

    Hu, Yi'na; Peng, Jian; Liu, Yanxu; Tian, Lu

    2018-06-01

    Ecosystem services are the benefits people obtain from ecosystems, and ecosystem services trade-offs have been widely applied to the development of land-use policy. Although previous studies have focused on trade-offs of ecosystem services, a scenario approach has been seldom used. The scenario approach can reveal the changes of ecosystem services for different land-use patterns in the future, and is of great significance for land-use decisions and ecosystem management. Based on the actual situation of deteriorating water quality and dwindling water supply in the Erhai Lake Basin of southwest China, this study put forward to convert paddy land to dry land (PLDL) in the basin, and simulated its potential impact on ecosystem services. Taking environmental pollution, social impact, economic benefit and residential participation into consideration, four scenarios of PLDL were designed. Then, four ecosystem services (water purification, water yield, soil conservation and rice production) were calculated for each scenario. The optimal scenario of PLDL in the Erhai Lake Basin was identified by trade-offs of the four ecosystem services. The results showed that the total nitrogen export could be reduced by 42.07% and water yield can be increased by 5.61% after converting 100% of paddy lands to dry land, thereby greatly improving the water quality and increasing the water yield of Erhai Lake. However, PLDL involving 100% of paddy lands also increased the sediment export by 17.22%, and eliminated rice production in the region. By comparing the four PLDL scenarios for converting just 50% of paddy lands, the residential participation scenario was identified to be the best choice for PLDL implementation because it achieved the best level of water purification and had the smallest negative effect on other ecosystem services. The optimal scenario for each township showed spatial differentiation, and there were conflicts between the optimal scenarios at basin scale and township

  4. GPS vertical axis performance enhancement for helicopter precision landing approach

    NASA Technical Reports Server (NTRS)

    Denaro, Robert P.; Beser, Jacques

    1986-01-01

    Several areas were investigated for improving vertical accuracy for a rotorcraft using the differential Global Positioning System (GPS) during a landing approach. Continuous deltaranging was studied and the potential improvement achieved by estimating acceleration was studied by comparing the performance on a constant acceleration turn and a rough landing profile of several filters: a position-velocity (PV) filter, a position-velocity-constant acceleration (PVAC) filter, and a position-velocity-turning acceleration (PVAT) filter. In overall statistics, the PVAC filter was found to be most efficient with the more complex PVAT performing equally well. Vertical performance was not significantly different among the filters. Satellite selection algorithms based on vertical errors only (vertical dilution of precision or VDOP) and even-weighted cross-track and vertical errors (XVDOP) were tested. The inclusion of an altimeter was studied by modifying the PVAC filter to include a baro bias estimate. Improved vertical accuracy during degraded DOP conditions resulted. Flight test results for raw differential results excluding filter effects indicated that the differential performance significantly improved overall navigation accuracy. A landing glidepath steering algorithm was devised which exploits the flexibility of GPS in determining precise relative position. A method for propagating the steering command over the GPS update interval was implemented.

  5. GPS Imaging of Global Vertical Land Motion for Sea Level Studies

    NASA Astrophysics Data System (ADS)

    Hammond, W. C.; Blewitt, G.; Hamlington, B. D.

    2015-12-01

    Coastal vertical land motion contributes to the signal of local relative sea level change. Moreover, understanding global sea level change requires understanding local sea level rise at many locations around Earth. It is therefore essential to understand the regional secular vertical land motion attributable to mantle flow, tectonic deformation, glacial isostatic adjustment, postseismic viscoelastic relaxation, groundwater basin subsidence, elastic rebound from groundwater unloading or other processes that can change the geocentric height of tide gauges anchored to the land. These changes can affect inferences of global sea level rise and should be taken into account for global projections. We present new results of GPS imaging of vertical land motion across most of Earth's continents including its ice-free coastlines around North and South America, Europe, Australia, Japan, parts of Africa and Indonesia. These images are based on data from many independent open access globally distributed continuously recording GPS networks including over 13,500 stations. The data are processed in our system to obtain solutions aligned to the International Terrestrial Reference Frame (ITRF08). To generate images of vertical rate we apply the Median Interannual Difference Adjusted for Skewness (MIDAS) algorithm to the vertical times series to obtain robust non-parametric estimates with realistic uncertainties. We estimate the vertical land motion at the location of 1420 tide gauges locations using Delaunay-based geographic interpolation with an empirically derived distance weighting function and median spatial filtering. The resulting image is insensitive to outliers and steps in the GPS time series, omits short wavelength features attributable to unstable stations or unrepresentative rates, and emphasizes long-wavelength mantle-driven vertical rates.

  6. Decoding the origins of vertical land motions observed today at coasts

    NASA Astrophysics Data System (ADS)

    Pfeffer, J.; Spada, G.; Mémin, A.; Boy, J.-P.; Allemand, P.

    2017-07-01

    In recent decades, geodetic techniques have allowed detecting vertical land motions and sea-level changes of a few millimetres per year, based on measurements taken at the coast (tide gauges), on board of satellite platforms (satellite altimetry) or both (Global Navigation Satellite System). Here, contemporary vertical land motions are analysed from January 1993 to July 2013 at 849 globally distributed coastal sites. The vertical displacement of the coastal platform due to surface mass changes is modelled using elastic and viscoelastic Green's functions. Special attention is paid to the effects of glacial isostatic adjustment induced by past and present-day ice melting. Various rheological and loading parameters are explored to provide a set of scenarios that could explain the coastal observations of vertical land motions globally. In well-instrumented regions, predicted vertical land motions explain more than 80 per cent of the variance observed at scales larger than a few hundred kilometres. Residual vertical land motions show a strong local variability, especially in the vicinity of plate boundaries due to the earthquake cycle. Significant residual signals are also observed at scales of a few hundred kilometres over nine well-instrumented regions forming observation windows on unmodelled geophysical processes. This study highlights the potential of our multitechnique database to detect geodynamical processes, driven by anthropogenic influence, surface mass changes (surface loading and glacial isostatic adjustment) and tectonic activity (including the earthquake cycle, sediment and volcanic loading, as well as regional tectonic constraints). Future improvements should be aimed at densifying the instrumental network and at investigating more thoroughly the uncertainties associated with glacial isostatic adjustment models.

  7. Quiet Cruise Efficient Short Take-off and Landing Subsonic Transport System

    NASA Technical Reports Server (NTRS)

    Kawai, Ron

    2008-01-01

    This NASA funded study conceived a revolutionary airplane concept to enable future traffic growth by using regional air space. This requires a very quiet airplane with STOL capability. Starting with a Blended Wing Body that is cruise efficient with inherent low noise characteristics from forward noise shielding and void of aft downward noise reflections, integration of embedded distributed propulsion enables incorporation of the revolutionary concept for jet noise shielding. Embedded distributed propulsion also enables incorporation of a fan bleed internally blown flap for quiet powered lift. The powered lift provides STOL capability for operation at regional airports with rapid take-off and descent to further reduce flyover noise. This study focused on configuring the total engine noise shielding STOL concept with a BWB airplane using the Boeing Phantom Works WingMOD multidisciplinary optimization code to define a planform that is pitch controllable. The configuration was then sized and mission data developed to enable NASA to assess the flyover and sideline noise. The foundational technologies needed are identified including military dual use benefits.

  8. Whole-body 3D kinematics of bird take-off: key role of the legs to propel the trunk

    NASA Astrophysics Data System (ADS)

    Provini, Pauline; Abourachid, Anick

    2018-02-01

    Previous studies showed that birds primarily use their hindlimbs to propel themselves into the air in order to take-off. Yet, it remains unclear how the different parts of their musculoskeletal system move to produce the necessary acceleration. To quantify the relative motions of the bones during the terrestrial phase of take-off, we used biplanar fluoroscopy in two species of birds, diamond dove ( Geopelia cuneata) and zebra finch ( Taeniopygia guttata). We obtained a detailed 3D kinematics analysis of the head, the trunk and the three long bones of the left leg. We found that the entire body assisted the production of the needed forces to take-off, during two distinct but complementary phases. The first one, a relatively slow preparatory phase, started with a movement of the head and an alignment of the different groups of bones with the future take-off direction. It was associated with a pitch down of the trunk and a flexion of the ankle, of the hip and, to a lesser extent, of the knee. This crouching movement could contribute to the loading of the leg muscles and store elastic energy that could be released in the propulsive phase of take-off, during the extension of the leg joints. Combined with the fact that the head, together with the trunk, produced a forward momentum, the entire body assisted the production of the needed forces to take-off. The second phase was faster with mostly horizontal forward and vertical upward translation motions, synchronous to an extension of the entire lower articulated musculoskeletal system. It led to the propulsion of the bird in the air with a fundamental role of the hip and ankle joints to move the trunk upward and forward. Take-off kinematics were similar in both studied species, with a more pronounced crouching movement in diamond dove, which can be related to a large body mass compared to zebra finch.

  9. Demographic dynamics and off-take of cattle herds in southern Mali.

    PubMed

    Ba, Alassane; Lesnoff, Matthieu; Poccard-Chapuis, Rene; Moulin, Charles-Henri

    2011-08-01

    The herds of 95 families were monitored for 1 year in eight villages in the cotton-growing region of southern Mali. In 2006-2007, reproduction performances were average, with 0.54 calvings/year per cow, and mortality was low. Herd numerical productivity is not very high, less than 0.13/year, because of the high proportion of males kept for animal draught. Depending on the herd size, the behaviour of the families differs, in terms of off-take and in-take of animals. Families that only have one or two draught animals seek to increase their animal draught capacity, with a negative net off-take (-0.13/year). Families with two to three cows have a very low net off-take (0.02/year), with culling of adult animals compensated by purchase. They therefore capitalised this year, with an annual herd growth of 8%. Families with a very large herd (20 to 50 cows) take off more of their stock, with a net off-take of 0.08/year (very few animal purchases) and make a stock growth of 5%. And finally, families with an average-sized herd (6 to 19 cows) take off the whole of the year's production, with a net off-take of 0.11/year and a nil stock growth rate. The use of a demographic model made it possible to measure the sensitivity of the productivity rate to the different demographic parameters.

  10. The global signature of post-1900 land ice wastage on vertical land motion

    NASA Astrophysics Data System (ADS)

    Riva, Riccardo; Frederikse, Thomas; King, Matt; Marzeion, Ben; van den Broeke, Michiel

    2017-04-01

    The amount of ice stored on land has strongly declined during the 20th century, and melt rates showed a significant acceleration over the last two decades. Land ice wastage is well known to be one of the main drivers of global mean sea-level rise, as widely discussed in the literature and reflected in the last assessment report of the IPCC. A less obvious effect of melting land ice is the response of the solid earth to mass redistribution on its surface, which, in the first approximation, results in land uplift where the load reduces (e.g., close to the meltwater sources) and land subsidence where the load increases (e.g., under the rising oceans). This effect is nowadays well known within the cryospheric and sea level communities. However, what is often not realized is that the solid earth response is a truly global effect: a localized mass change does cause a large deformation signal in its proximity, but also causes a change of the position of every other point on the Earth's surface. The theory of the Earth's elastic response to changing surface loads forms the basis of the 'sea-level equation', which allows sea-level fingerprints of continental mass change to be computed. In this paper, we provide the first dedicated analysis of global vertical land motion driven by land ice wastage. By means of established techniques to compute the solid earth elastic response to surface load changes and the most recent datasets of glacier and ice sheet mass change, we show that land ice loss currently leads to vertical deformation rates of several tenths of mm per year at mid-latitudes, especially over the Northern Hemisphere where most sources are located. In combination with the improved accuracy of space geodetic techniques (e.g., Global Navigation Satellite Systems), this means that the effect of ice melt is non-negligible over a large part of the continents. In particular, we show how deformation rates have been strongly varying through the last century, which implies

  11. A Short Take-Off/Vertical Landing (STOVL) Aircraft Carrier (S-CVX).

    DTIC Science & Technology

    1998-05-01

    distance for the S-CVXcan be covered in less than 20 days at 25 kts even with a half-day stop for refueling. Transit time differences for Norfolk to...efficiency concerns will result in a rather limited selection of basic weapon types with variants to accommodate different mission requirements. This...components shall be decontaminated through use of a countermeasure wash down system and portable Decontamination (DECON) methods . This requirement

  12. Spray Characteristics and Take-off and Landing Stability of Several Modifications of a 1/8-size Model of the PBN-1 Flying Boad - NACA Model 192

    DTIC Science & Technology

    1945-04-01

    di s:{S . Tni s ra~ge, v:hi ch e): tended 1 fl’om 8.;;;· to 13 feet per seconei for the basi c model 192, L WaS :;,’oc.uced to Cl. range froLl 91...f$i I5-::J:n P.r~ !~~pg l :: fh’ t", l -!- : lli~ i# f! ~~ itt ~ ~rt! Im~ :; ::! I ~+ ~I~$1 :~ I ~=:~ I :-:r. .r:::J r.;.; 1111: :tli Uti h!fl : mIlia ...CHARACTERISTICS AND TAKE-OFF AND LANDING STABILITY OF SEVERAL MODIFICATIONS OF A l /8-SI’EE MODEL OF THE PBN- l FInNG BOAT - NACA MODEL 192 By David

  13. Preliminary design of a supersonic Short-Takeoff and Vertical-Landing (STOVL) fighter aircraft

    NASA Technical Reports Server (NTRS)

    1990-01-01

    A preliminary study of a supersonic short takeoff and vertical landing (STOVL) fighter is presented. Three configurations (a lift plus lift/cruise concept, a hybrid fan vectored thrust concept, and a mixed flow vectored thrust concept) were initially investigated with one configuration selected for further design analysis. The selected configuration, the lift plus lift/cruise concept, was successfully integrated to accommodate the powered lift short takeoff and vertical landing requirements as well as the demanding supersonic cruise and point performance requirements. A supersonic fighter aircraft with a short takeoff and vertical landing capability using the lift plus lift/cruise engine concept seems a viable option for the next generation fighter.

  14. A comparison of take-off dynamics during three different spikes, block and counter-movement jump in female volleyball players.

    PubMed

    Kabacinski, Jaroslae; Dworak, Lecholslaw B; Murawa, Michal; Ostarello, John; Rzepnicka, Agata; Maczynski, Jacek

    2016-12-01

    The purpose of the study was to compare the take-off dynamics in counter-movement jump (CMJ), volleyball block and spikes. Twelve professional female players, representing the highest volleyball league in Poland, participated in the laboratory tests. A force platform was used to record ground reaction force (GRF) during take-off phase in CMJ test, block from a run-up and spikes: front row attack, slide attack, back row attack. Vertical (v) GRF (peak: Rmax and integral mean: ), impulse of vGRF (J) and mechanical power (peak: Pmax and integral mean:

    ) were analyzed. Significant differences (P<0.05) of values of the dynamic parameters (Rmax, , J, Pmax, and

    ) were found between CMJ, block from a run-up and three different technique spikes. The highest values were recorded during take-off in the back row attack: peak vGRF (2.93±0.05 BW), integral mean vGRF (1.90±0.08 BW), impulse of vGRF (354±40 Ns), peak power (5320±918 W) and integral mean power (3604±683 W). Peak power (2608±217 W) and integral mean power (1417±94 W) were determined in CMJ test to evaluate the force-velocity capabilities of the players. In terms of GRF and the mechanical power, high level of dynamics in take-off influences positively the jumping height and significantly increases the effectiveness of attacks during spike of the ball over the block of the opponent.

  15. 24. UPPER STATION, LOWER FLOOR, MOTOR ROOM, OFF VERTICAL DEFLECTOR ...

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

    24. UPPER STATION, LOWER FLOOR, MOTOR ROOM, OFF VERTICAL DEFLECTOR SHEAVE, MOTOR, BRAKE, PINION SHAFT, DRIVE WHEEL. - Monongahela Incline Plane, Connecting North side of Grandview Avenue at Wyoming Street with West Carson Street near Smithfield Street, Pittsburgh, Allegheny County, PA

  16. XB-70A during take-off

    NASA Image and Video Library

    1965-08-17

    Viewed from the front the #1 XB-70A (62-0001) is shown climbing out during take-off. Most flights were scheduled during the morning hours to take advantage of the cooler ambient air temperatures for improved propulsion efficiencies. The wing tips are extended straight out to provide a maximum lifting wing surface. The XB-70A, capable of flying three times the speed of sound, was the world's largest experimental aircraft in the 1960s. Two XB-70A aircraft were built. Ship #1 was flown by NASA in a high speed flight research program.

  17. Off-vertical rotation produces conditioned taste aversion and suppressed drinking in mice

    NASA Technical Reports Server (NTRS)

    Fox, R. A.; Lauber, A. H.; Daunton, N. G.; Phillips, M.; Diaz, L.

    1984-01-01

    The effects of off-vertical rotation upon the intake of tap water immediately after rotation and upon conditioned taste aversion were assessed in mice with the tilt of the rotation axis varying from 5 to 20 deg from the earth-vertical. Conditioned taste aversion occurred in all mice that were rotated, but the intake of tap water was suppressed only in mice that were rotated at 15 or 20 deg of tilt. The greater suppression of tap-water intake and the stronger conditioned aversion in the mouse as the angle of tilt was increased in this experiment are consistent with predictions from similar experiments with human subjects, where motion sickness develops more rapidly as the angle of tilt is increased. It was suggested that off-vertical rotation may be a useful procedure for insuring experimental control over vestibular stimulation in animal studies of motion sickness.

  18. Off-Nadir Hyperspectral Sensing for Estimation of Vertical Profile of Leaf Chlorophyll Content within Wheat Canopies

    PubMed Central

    Huang, Wenjiang; Zhou, Xianfeng; Ye, Huichun; Dong, Yingying

    2017-01-01

    , while the optimized SR-like index was recommended for the bottom Chl estimation due to its simple and universal form. We suggest that it is necessary to take into account the penetration characteristic of the light inside the canopy for different Chl absorption regions of the spectrum and the formula used to derive spectral index when estimating the vertical profile of leaf Chl content using off-nadir hyperspectral data. PMID:29168757

  19. Off-Nadir Hyperspectral Sensing for Estimation of Vertical Profile of Leaf Chlorophyll Content within Wheat Canopies.

    PubMed

    Kong, Weiping; Huang, Wenjiang; Casa, Raffaele; Zhou, Xianfeng; Ye, Huichun; Dong, Yingying

    2017-11-23

    , while the optimized SR-like index was recommended for the bottom Chl estimation due to its simple and universal form. We suggest that it is necessary to take into account the penetration characteristic of the light inside the canopy for different Chl absorption regions of the spectrum and the formula used to derive spectral index when estimating the vertical profile of leaf Chl content using off-nadir hyperspectral data.

  20. Escaping blood-fed malaria mosquitoes minimize tactile detection without compromising on take-off speed.

    PubMed

    Muijres, F T; Chang, S W; van Veen, W G; Spitzen, J; Biemans, B T; Koehl, M A R; Dudley, R

    2017-10-15

    To escape after taking a blood meal, a mosquito must exert forces sufficiently high to take off when carrying a load roughly equal to its body weight, while simultaneously avoiding detection by minimizing tactile signals exerted on the host's skin. We studied this trade-off between escape speed and stealth in the malaria mosquito Anopheles coluzzii using 3D motion analysis of high-speed stereoscopic videos of mosquito take-offs and aerodynamic modeling. We found that during the push-off phase, mosquitoes enhanced take-off speed using aerodynamic forces generated by the beating wings in addition to leg-based push-off forces, whereby wing forces contributed 61% of the total push-off force. Exchanging leg-derived push-off forces for wing-derived aerodynamic forces allows the animal to reduce peak force production on the host's skin. By slowly extending their long legs throughout the push-off, mosquitoes spread push-off forces over a longer time window than insects with short legs, thereby further reducing peak leg forces. Using this specialized take-off behavior, mosquitoes are capable of reaching take-off speeds comparable to those of similarly sized fruit flies, but with weight-normalized peak leg forces that were only 27% of those of the fruit flies. By limiting peak leg forces, mosquitoes possibly reduce the chance of being detected by the host. The resulting combination of high take-off speed and low tactile signals on the host might help increase the mosquito's success in escaping from blood-hosts, which consequently also increases the chance of transmitting vector-borne diseases, such as malaria, to future hosts. © 2017. Published by The Company of Biologists Ltd.

  1. Transition from leg to wing forces during take-off in birds.

    PubMed

    Provini, Pauline; Tobalske, Bret W; Crandell, Kristen E; Abourachid, Anick

    2012-12-01

    Take-off mechanics are fundamental to the ecology and evolution of flying animals. Recent research has revealed that initial take-off velocity in birds is driven mostly by hindlimb forces. However, the contribution of the wings during the transition to air is unknown. To investigate this transition, we integrated measurements of both leg and wing forces during take-off and the first three wingbeats in zebra finch (Taeniopygia guttata, body mass 15 g, N=7) and diamond dove (Geopelia cuneata, body mass 50 g, N=3). We measured ground reaction forces produced by the hindlimbs using a perch mounted on a force plate, whole-body and wing kinematics using high-speed video, and aerodynamic forces using particle image velocimetry (PIV). Take-off performance was generally similar between species. When birds were perched, an acceleration peak produced by the legs contributed to 85±1% of the whole-body resultant acceleration in finch and 77±6% in dove. At lift-off, coincident with the start of the first downstroke, the percentage of hindlimb contribution to initial flight velocity was 93.6±0.6% in finch and 95.2±0.4% in dove. In finch, the first wingbeat produced 57.9±3.4% of the lift created during subsequent wingbeats compared with 62.5±2.2% in dove. Advance ratios were <0.5 in both species, even when taking self-convection of shed vortices into account, so it was likely that wing-wake interactions dominated aerodynamics during wingbeats 2 and 3. These results underscore the relatively low contribution of the wings to initial take-off, and reveal a novel transitional role for the first wingbeat in terms of force production.

  2. NACA Photographer North American F-100A (NACA-200) Super Sabre Airplane take-off. The blowing-tupe

    NASA Technical Reports Server (NTRS)

    1957-01-01

    NACA Photographer North American F-100A (NACA-200) Super Sabre Airplane take-off. The blowing-tupe boundary-layer control on the leading- and trailing-edge provided large reductions in takeoff and landing approach speeds. Approach speeds were reduced by about 10 knots (Mar 1960). Note: Used in publication in Flight Research at Ames; 57 Years of Development and Validation of Aeronautical Technology NASA SP-1998-3300 fig. 102 and and Memoirs of a Flight Test Engneer NASA SP-2002-4525

  3. Determinants of land take at the regional scale: a study concerning Sardinia (Italy)

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

    Zoppi, Corrado, E-mail: zoppi@unica.it; Lai, Sabrina, E-mail: sabrinalai@unica.it

    In its “Roadmap to a Resource Efficient Europe” (Communication COM(2011) 571 of 20 September 2011), the European Commission (EC) established an ambitious goal for the European Union (EU), that of achieving no land take by 2050; towards this aim, a key milestone for the year 2020 was set, by stating that European policies in the programming period 2014–2020 ought to consider both their direct and their indirect impacts on land use in the EU. Within this framework, this paper builds upon the findings of a previous paper (Zoppi and Lai, 2014), in which we estimated the magnitude of land takemore » over a short period of time (2003–2008) in Sardinia, an Italian NUTS2 region, and we assessed whether and how land take is related to a set of variables that are regarded as important determinants in the literature, such as parcel size, accessibility, and proximity to main cities and towns, to the coastline, or to protected areas. In this paper we study the land-taking process taking Sardinia as a case study, in two larger time periods, 1960–1990 and 1990–2008. We assess if, and to what extent, these factors reveal similar, or different, effects in the two periods, and try to identify consistencies concerning the determinants of land take. - Highlights: • Population density and parcel size significantly affect the magnitude of land take. • The presence of nature conservation areas hinders land taking processes. • Extensive urbanization might effectively preserve non-artificial land. • Balanced accessibility of settlements and nature conservation regional policies can effectively contrast land take. • Size of non-artificial land parcels that become artificial is negatively and significantly connected to land take.« less

  4. Theseus Take-off from Rogers Dry Lake

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Theseus prototype research aircraft shows off its high aspect-ratio wing in this rear view of the aircraft as it takes off on its first test flight from NASA's Dryden Flight Research Center, Edwards, California, on May 24, 1996. The Theseus aircraft, built and operated by Aurora Flight Sciences Corporation, Manassas, Virginia, was a unique aircraft flown at NASA's Dryden Flight Research Center, Edwards, California, under a cooperative agreement between NASA and Aurora. Dryden hosted the Theseus program, providing hangar space and range safety for flight testing. Aurora Flight Sciences was responsible for the actual flight testing, vehicle flight safety, and operation of the aircraft. The Theseus remotely piloted aircraft flew its maiden flight on May 24, 1996, at Dryden. During its sixth flight on November 12, 1996, Theseus experienced an in-flight structural failure that resulted in the loss of the aircraft. As of the beginning of the year 2000, Aurora had not rebuilt the aircraft Theseus was built for NASA under an innovative, $4.9 million fixed-price contract by Aurora Flight Sciences Corporation and its partners, West Virginia University, Morgantown, West Virginia, and Fairmont State College, Fairmont, West Virginia. The twin-engine, unpiloted vehicle had a 140-foot wingspan, and was constructed largely of composite materials. Powered by two 80-horsepower, turbocharged piston engines that drove twin 9-foot-diameter propellers, Theseus was designed to fly autonomously at high altitudes, with takeoff and landing under the active control of a ground-based pilot in a ground control station 'cockpit.' With the potential ability to carry 700 pounds of science instruments to altitudes above 60,000 feet for durations of greater than 24 hours, Theseus was intended to support research in areas such as stratospheric ozone depletion and the atmospheric effects of future high-speed civil transport aircraft engines. Instruments carried aboard Theseus also would be able

  5. Step-off, vertical electromagnetic responses of a deep resistivity layer buried in marine sediments

    NASA Astrophysics Data System (ADS)

    Jang, Hangilro; Jang, Hannuree; Lee, Ki Ha; Kim, Hee Joon

    2013-04-01

    A frequency-domain, marine controlled-source electromagnetic (CSEM) method has been applied successfully in deep water areas for detecting hydrocarbon (HC) reservoirs. However, a typical technique with horizontal transmitters and receivers requires large source-receiver separations with respect to the target depth. A time-domain EM system with vertical transmitters and receivers can be an alternative because vertical electric fields are sensitive to deep resistive layers. In this paper, a time-domain modelling code, with multiple source and receiver dipoles that are finite in length, has been written to investigate transient EM problems. With the use of this code, we calculate step-off responses for one-dimensional HC reservoir models. Although the vertical electric field has much smaller amplitude of signal than the horizontal field, vertical currents resulting from a vertical transmitter are sensitive to resistive layers. The modelling shows a significant difference between step-off responses of HC- and water-filled reservoirs, and the contrast can be recognized at late times at relatively short offsets. A maximum contrast occurs at more than 4 s, being delayed with the depth of the HC layer.

  6. ACL-reconstructed and ACL-deficient individuals show differentiated trunk, hip, and knee kinematics during vertical hops more than 20 years post-injury.

    PubMed

    Markström, Jonas L; Tengman, Eva; Häger, Charlotte K

    2018-02-01

    Little is known regarding movement strategies in the long term following injury of the anterior cruciate ligament (ACL), and even less about comparisons of reconstructed and deficient knees in relation to healthy controls. The present purpose was to compare trunk, hip, and knee kinematics during a one-leg vertical hop (VH) ~20 years post-ACL injury between persons treated with surgery and physiotherapy (ACL R ), solely physiotherapy (ACL PT ), and controls (CTRL). Between-leg kinematic differences within groups were also investigated. Sixty-six persons who suffered unilateral ACL injury on average 23 ± 2 years ago (32 ACL R , 34 ACL PT ) and 33 controls performed the VH. Peak trunk, hip, and knee angles during Take-off and Landing phases recorded with a 3D motion capture system were analysed with multivariate statistics. Significant group effects during both Take-off and Landing were found, with ACL PT differing from CTRL in Take-off with a combination of less knee flexion and knee internal rotation, and from both ACL R and CTRL in Landing with less hip and knee flexion, knee internal rotation, and greater hip adduction. ACL R also presented different kinematics to ACL PT and CTRL in Take-off with a combination of greater trunk flexion, hip flexion, hip internal rotation, and less knee abduction, and in Landing with greater trunk flexion and hip internal rotation. Further, different kinematics and hop height were found between legs within groups in both Take-off and Landing for both ACL groups, but not for CTRL. Different kinematics for the injured leg for both ACL groups compared to CTRL and between treatment groups, as well as between legs within treatment groups, indicate long-term consequences of injury. Compensatory mechanisms for knee protection seem to prevail over time irrespective of initial treatment, possibly increasing the risk of re-injury and triggering the development of osteoarthritis. Detailed investigation of movement strategies during the VH

  7. Pegasus XL CYGNSS Launch Attempt; Scrubbed - Take Off

    NASA Image and Video Library

    2016-12-12

    An Orbital ATK L-1011 Stargazer aircraft carrying a Pegasus XL Rocket with eight NASA Cyclone Global Navigation Satellite System, or CYGNSS, spacecraft takes off from the Skid Strip at Cape Canaveral Air Force Station, Florida. With the aircraft flying off shore, the Pegasus rocket will be released. Five seconds later, the solid propellant engine will ignite and boost the eight hurricane observatories to orbit. The eight CYGNSS satellites will make frequent and accurate measurements of ocean surface winds throughout the life cycle of tropical storms and hurricanes.

  8. Aerodynamic consequences of wing morphing during emulated take-off and gliding in birds.

    PubMed

    Klaassen van Oorschot, Brett; Mistick, Emily A; Tobalske, Bret W

    2016-10-01

    Birds morph their wings during a single wingbeat, across flight speeds and among flight modes. Such morphing may allow them to maximize aerodynamic performance, but this assumption remains largely untested. We tested the aerodynamic performance of swept and extended wing postures of 13 raptor species in three families (Accipitridae, Falconidae and Strigidae) using a propeller model to emulate mid-downstroke of flapping during take-off and a wind tunnel to emulate gliding. Based on previous research, we hypothesized that (1) during flapping, wing posture would not affect maximum ratios of vertical and horizontal force coefficients (C V :C H ), and that (2) extended wings would have higher maximum C V :C H when gliding. Contrary to each hypothesis, during flapping, extended wings had, on average, 31% higher maximum C V :C H ratios and 23% higher C V than swept wings across all biologically relevant attack angles (α), and, during gliding, maximum C V :C H ratios were similar for the two postures. Swept wings had 11% higher C V than extended wings in gliding flight, suggesting flow conditions around these flexed raptor wings may be different from those in previous studies of swifts (Apodidae). Phylogenetic affiliation was a poor predictor of wing performance, due in part to high intrafamilial variation. Mass was only significantly correlated with extended wing performance during gliding. We conclude that wing shape has a greater effect on force per unit wing area during flapping at low advance ratio, such as take-off, than during gliding. © 2016. Published by The Company of Biologists Ltd.

  9. Comparison of the take-off ground reaction force patterns of the pole vault and the long jump.

    PubMed

    Plessa, E I; Rousanoglou, E N; Boudolos, K D

    2010-12-01

    The take-off is probably the most important phase of the pole vault. The kinematics of pole vault take-off is often described in comparison to the long jump take-off. If a kinetic similarity were also evidenced, the extra loading of carrying the pole could be avoided by using the long jump style take-off drills in pole vault take-off training. However, to our knowledge, a direct comparison of the take-off ground reaction force (GRF) pattern of the two types of jump has not been reported in the scientific or coaching literature. The purpose of this study was to compare the take-off GRF patterns of the support leg in the pole vault and the long jump. Twelve elite women jumpers undertook pole vault and long jump trials. The take-off GRF patterns were recorded by a force plate (Kistler-9286AA). Temporal and force parameters were determined for all three GRF components. Trials were videotaped to determine the take-off kinematics. Paired sample t-tests (SPSS 13.0) were applied (P≤0.05) for comparison between jumps. No significant differences were found in kinematics (P>0.05). Overall, the GRF patterns were similar, although there were particular significant (P≤0.05) differences in contact times, impulses and force peaks. This study provides scientific support for potential use of the long jump take-off drills during technical preparation for the pole vault take-off.

  10. Hybrid vehicle powertrain system with power take-off driven vehicle accessory

    DOEpatents

    Beaty, Kevin D.; Bockelmann, Thomas R.; Zou, Zhanijang; Hope, Mark E.; Kang, Xiaosong; Carpenter, Jeffrey L.

    2006-09-12

    A hybrid vehicle powertrain system includes a first prime mover, a first prime mover driven power transmission mechanism having a power take-off adapted to drive a vehicle accessory, and a second prime mover. The second prime mover is operable to drive the power transmission mechanism alone or in combination with the first prime mover to provide power to the power take-off through the power transmission mechanism. The invention further includes methods for operating a hybrid vehicle powertrain system.

  11. Investigation of Effectiveness of a Wing Equipped with a 50-percent-chord Sliding Flap, a 30-percent-chord Slotted Flap, and a 30-percent-chord Slat in Deflecting Propeller Slipstreams Downward for Vertical Take-off

    NASA Technical Reports Server (NTRS)

    Kuhn, Richard E

    1957-01-01

    Results are presented of an investigation of the effectiveness of a wing equipped with a 50-percent-chord sliding flap and a 30-percent-chord slotted flap in deflecting a propeller slipstream downward for vertical take-off. Tests were conducted at zero forward speed in a large room and included the effects of flap deflection, proximity to the ground, a leading-edge slat, and end plates. A turning angle of about 70 degrees and a resultant force of about 100 percent of the thrust were achieved near the ground. Out of the ground-effect region, the turning angle was also about 70 degrees but the resultant force was reduced to about 86 percent of the thrust.

  12. Take-off and Landing

    DTIC Science & Technology

    1975-01-01

    Studies Program. The results of AGARD work are reported to the member nations and the NATO Authorities through the AGARD series of publications of...calculated based on a low altitude mission profile. 2. GROUND RULES AND BASIC ASSUMPTIONS Base Design All aircraft synthesized for this study are...In this study manoeuverability is defined in terms of specific excess power (as shown in Fig. 5) at specified Mach number, altitude,and load

  13. The calculated effect of trailing-edge flaps on the take-off of flying boats

    NASA Technical Reports Server (NTRS)

    Parkinson, J E; Bell, J W

    1934-01-01

    The results of take-off calculations are given for an application of simple trailing-edge flaps to two hypothetical flying boats, one having medium wing and power loading and consequently considerable excess of thrust over total resistance during the take-off run, the other having high wing and power loading and a very low excess thrust. For these seaplanes the effect of downward flap settings was: (1) to increase the total resistance below the stalling speed, (2) to decrease the get-away speed, (3) to improve the take-off performance of the seaplane having considerable excess thrust, and (4) to hinder the take-off of the seaplane having low excess thrust. It is indicated that flaps would allow a decrease in the high angles of wing setting necessary with most seaplanes, provided that the excess thrust is not too low.

  14. Brief communication: The global signature of post-1900 land ice wastage on vertical land motion

    NASA Astrophysics Data System (ADS)

    Riva, Riccardo E. M.; Frederikse, Thomas; King, Matt A.; Marzeion, Ben; van den Broeke, Michiel R.

    2017-06-01

    Melting glaciers, ice caps and ice sheets have made an important contribution to sea-level rise through the last century. Self-attraction and loading effects driven by shrinking ice masses cause a spatially varying redistribution of ocean waters that affects reconstructions of past sea level from sparse observations. We model the solid-earth response to ice mass changes and find significant vertical deformation signals over large continental areas. We show how deformation rates have been strongly varying through the last century, which implies that they should be properly modelled before interpreting and extrapolating recent observations of vertical land motion and sea-level change.

  15. Flight evaluations of several hover control and display combinations for precise blind vertical landings

    NASA Technical Reports Server (NTRS)

    Schroeder, J. A.; Merrick, V. K.

    1990-01-01

    Several control and display concepts were evaluated on a variable-stability helicopter prior to future evaluations on a modified Harrier. The control and display concepts had been developed to enable precise hover maneuvers, station keeping, and vertical landings in simulated zero-visibility conditions and had been evaluated extensively in previous piloted simulations. Flight evaluations early in the program revealed several inadequacies in the display drive laws that were later corrected using an alternative design approach that integrated the control and display characteristics with the desired guidance law. While hooded, three pilots performed landing-pad captures followed by vertical landings with attitude-rate, attitude, and translation-velocity-command control systems. The latter control system incorporated a modified version of state-rate-feedback implicit-model following. Precise landing within 2 ft of the desired touchdown point were achieved.

  16. Validation of the iPhone app using the force platform to estimate vertical jump height.

    PubMed

    Carlos-Vivas, Jorge; Martin-Martinez, Juan P; Hernandez-Mocholi, Miguel A; Perez-Gomez, Jorge

    2018-03-01

    Vertical jump performance has been evaluated with several devices: force platforms, contact mats, Vertec, accelerometers, infrared cameras and high-velocity cameras; however, the force platform is considered the gold standard for measuring vertical jump height. The purpose of this study was to validate an iPhone app called My Jump, that measures vertical jump height by comparing it with other methods that use the force platform to estimate vertical jump height, namely, vertical velocity at take-off and time in the air. A total of 40 sport sciences students (age 21.4±1.9 years) completed five countermovement jumps (CMJs) over a force platform. Thus, 200 CMJ heights were evaluated from the vertical velocity at take-off and the time in the air using the force platform, and from the time in the air with the My Jump mobile application. The height obtained was compared using the intraclass correlation coefficient (ICC). Correlation between APP and force platform using the time in the air was perfect (ICC=1.000, P<0.001). Correlation between APP and force platform using the vertical velocity at take-off was also very high (ICC=0.996, P<0.001), with an error margin of 0.78%. Therefore, these results showed that application, My Jump, is an appropriate method to evaluate the vertical jump performance; however, vertical jump height is slightly overestimated compared with that of the force platform.

  17. Evaluation of Flying Qualities and Guidance Displays for an Advanced Tilt-Wing STOL Transport Aircraft in Final Approach and Landing

    NASA Technical Reports Server (NTRS)

    Frost, Chad R.; Franklin, James A.; Hardy, Gordon H.

    2002-01-01

    A piloted simulation was performed on the Vertical Motion Simulator at NASA Ames Research Center to evaluate flying qualities of a tilt-wing Short Take-Off and Landing (STOL) transport aircraft during final approach and landing. The experiment was conducted to assess the design s handling qualities, and to evaluate the use of flightpath-centered guidance for the precision approach and landing tasks required to perform STOL operations in instrument meteorological conditions, turbulence, and wind. Pilots rated the handling qualities to be satisfactory for all operations evaluated except those encountering extreme crosswinds and severe windshear; even in these difficult meteorological conditions, adequate handling qualities were maintained. The advanced flight control laws and guidance displays provided consistent performance and precision landings.

  18. Horizontal and vertical species turnover in tropical birds in habitats with differing land use.

    PubMed

    Sreekar, Rachakonda; Corlett, Richard T; Dayananda, Salindra; Goodale, Uromi Manage; Kilpatrick, Adam; Kotagama, Sarath W; Koh, Lian Pin; Goodale, Eben

    2017-05-01

    Large tracts of tropical rainforests are being converted into intensive agricultural lands. Such anthropogenic disturbances are known to reduce species turnover across horizontal distances. But it is not known if they can also reduce species turnover across vertical distances (elevation), which have steeper climatic differences. We measured turnover in birds across horizontal and vertical sampling transects in three land-use types of Sri Lanka: protected forest, reserve buffer and intensive-agriculture, from 90 to 2100 m a.s.l. Bird turnover rates across horizontal distances were similar across all habitats, and much less than vertical turnover rates. Vertical turnover rates were not similar across habitats. Forest had higher turnover rates than the other two habitats for all bird species. Buffer and intensive-agriculture had similar turnover rates, even though buffer habitats were situated at the forest edge. Therefore, our results demonstrate the crucial importance of conserving primary forest across the full elevational range available. © 2017 The Author(s).

  19. Fast Regulation of Vertical Squat Jump during Push-Off in Skilled Jumpers

    PubMed Central

    Fargier, Patrick; Massarelli, Raphael; Rabahi, Tahar; Gemignani, Angelo; Fargier, Emile

    2016-01-01

    The height of a maximum Vertical Squat Jump (VSJ) reflects the useful power produced by a jumper during the push-off phase. In turn this partly depends on the coordination of the jumper's segmental rotations at each instant. The physical system constituted by the jumper has been shown to be very sensitive to perturbations and furthermore the movement is realized in a very short time (ca. 300 ms), compared to the timing of known feedback loops. However, the dynamics of the segmental coordination and its efficiency in relation to energetics at each instant of the push-off phase still remained to be clarified. Their study was the main purpose of the present research. Eight young adult volunteers (males) performed maximal VSJ. They were skilled in jumping according to their sport activities (track and field or volleyball). A video analysis on the kinematics of the jump determined the influence of the jumpers' segments rotation on the vertical velocity and acceleration of the body mass center (MC). The efficiency in the production of useful power at the jumpers' MC level, by the rotation of the segments, was measured in consequence. The results showed a great variability in the segmental movements of the eight jumpers, but homogeneity in the overall evolution of these movements with three consecutive types of coordination in the second part of the push-off (lasting roughly 0.16 s). Further analyses gave insights on the regulation of the push-off, suggesting that very fast regulation(s) of the VSJ may be supported by: (a) the adaptation of the motor cerebral programming to the jumper's physical characteristics; (b) the control of the initial posture; and (c) the jumper's perception of the position of his MC relative to the ground reaction force, during push-off, to reduce energetic losses. PMID:27486404

  20. Fast Regulation of Vertical Squat Jump during Push-Off in Skilled Jumpers.

    PubMed

    Fargier, Patrick; Massarelli, Raphael; Rabahi, Tahar; Gemignani, Angelo; Fargier, Emile

    2016-01-01

    The height of a maximum Vertical Squat Jump (VSJ) reflects the useful power produced by a jumper during the push-off phase. In turn this partly depends on the coordination of the jumper's segmental rotations at each instant. The physical system constituted by the jumper has been shown to be very sensitive to perturbations and furthermore the movement is realized in a very short time (ca. 300 ms), compared to the timing of known feedback loops. However, the dynamics of the segmental coordination and its efficiency in relation to energetics at each instant of the push-off phase still remained to be clarified. Their study was the main purpose of the present research. Eight young adult volunteers (males) performed maximal VSJ. They were skilled in jumping according to their sport activities (track and field or volleyball). A video analysis on the kinematics of the jump determined the influence of the jumpers' segments rotation on the vertical velocity and acceleration of the body mass center (MC). The efficiency in the production of useful power at the jumpers' MC level, by the rotation of the segments, was measured in consequence. The results showed a great variability in the segmental movements of the eight jumpers, but homogeneity in the overall evolution of these movements with three consecutive types of coordination in the second part of the push-off (lasting roughly 0.16 s). Further analyses gave insights on the regulation of the push-off, suggesting that very fast regulation(s) of the VSJ may be supported by: (a) the adaptation of the motor cerebral programming to the jumper's physical characteristics; (b) the control of the initial posture; and (c) the jumper's perception of the position of his MC relative to the ground reaction force, during push-off, to reduce energetic losses.

  1. Vertical velocity in oceanic convection off tropical Australia

    NASA Technical Reports Server (NTRS)

    Lucas, Christopher; Zipser, Edward J.; Lemone, Margaret A.

    1994-01-01

    Time series of 1-Hz vertical velocity data collected during aircraft penetrations of oceanic cumulonimbus clouds over the western Pacific warm pool as part of the Equatorial Mesoscale Experiment (EMEX) are analyzed for updraft and downdraft events called cores. An updraft core is defined as occurring whenever the vertical velocity exceeds 1 m/sec for at least 500 m. A downdraft core is defined analogously. Over 19,000 km of straight and level flight legs are used in the analysis. Five hundred eleven updraft cores and 253 downdraft cores are included in the dataset. Core properties are summarized as distributions of average and maximum vertical velocity, diameter, and mass flux in four altitude intervals between 0.2 and 5.8 km. Distributions are approximately lognormal at all levels. Examination of the variation of the statistics with height suggests a maximum in vertical velocity between 2 and 3 km; slightly lower or equal vertical velocity is indicated at 5 km. Near the freezing level, virtual temperature deviations are found to be slightly positive for both updraft and downdraft cores. The excess in updraft cores is much smaller than that predicted by parcel theory. Comparisons with other studies that use the same analysis technique reveal that EMEX cores have approximately the same strength as cores of other oceanic areas, despite warmer sea surface temperatures. Diameter and mass flux are greater than those in the Global Atmospheric Research Program (GATE) but smaller than those in hurricane rainbands. Oceanic cores are much weaker and appear to be slightly smaller than those observed over land during the Thunderstorm Project. The markedly weaker oceanic vertical velocities below 5.8 km (compared to the continental cores) cannot be attributed to smaller total convective available potential energy or to very high water loading. Rather, it is suggested that water loading, although less than adiabatic, is more effective in reducing buoyancy of oceanic cores

  2. Kinetic factors of vertical jumping for heading a ball in flexible flatfooted amateur soccer players with and without insole adoption.

    PubMed

    Arastoo, Ali Asghar; Aghdam, Esmaeil Moharrami; Habibi, Abdoul Hamid; Zahednejad, Shahla

    2014-06-01

    According to literature, little is known regarding the effects of orthotic management of flatfoot on kinetics of vertical jump. To compare the kinetic and temporal events of two-legged vertical jumping take-off from a force plate for heading a ball in normal and flexible flatfoot subjects with and without insole. A functional based interventional controlled study. Random sampling method was employed to draw a control group of 15 normal foot subjects to a group of 15 flatfoot subjects. A force platform was used to record kinetics of two-legged vertical jump shots. Results indicate that insole did not lead to a significant effect on kinetics regarding anterior-posterior and mediolateral directions (p > 0.05). Results of kinetics related to vertical direction for maximum force due to take-off and stance duration revealed significant differences between the normal and flexible flatfoot subjects without insole (p < 0.05) and no significant differences between the normal foot and flexible flatfoot subjects with insole adoption (p > 0.05). These results suggest that the use of an insole in the flexible flatfoot subjects led to improved stance time and decrease of magnitude of kinetics regarding vertical direction at take-off as the main feature of two-legged vertical jumping function. Adoption of the insole improved the design of the shoe-foot interface support for the flexible flatfoot athletes, enabling them to develop more effective take-off kinetics for vertical jumping in terms of ground reaction force and stance duration similar to that of normal foot subjects without insole. © The International Society for Prosthetics and Orthotics 2013.

  3. Characteristics of a Single Float Seaplane During Take-off

    NASA Technical Reports Server (NTRS)

    Crowley, J W , Jr; Ronan, K M

    1925-01-01

    At the request of the Bureau of Aeronautics, Navy Department, the National Advisory Committee for Aeronautics at Langley Field is investigating the get-away characteristics of an N-9H, a DT-2, and an F-5l, as representing, respectively, a single float, a double float, and a boat type of seaplane. This report covers the investigation conducted on the N-9H. The results show that a single float seaplane trims aft in taking off. Until a planing condition is reached the angle of attack is about 15 degrees and is only slightly affected by controls. When planing it seeks a lower angle, but is controllable through a widening range, until at the take-off it is possible to obtain angles of 8 degrees to 15 degrees with corresponding speeds of 53 to 41 M. P. H. or about 40 per cent of the speed range. The point of greatest resistance occurs at about the highest angle of a pontoon planing angle of 9 1/2 degrees and at a water speed of 24 M. P. H.

  4. Theseus on Take-off for First Flight

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The Theseus prototype research aircraft takes off for its first test flight from NASA's Dryden Flight Research Center, Edwards, California, on May 24, 1996. The Theseus aircraft, built and operated by Aurora Flight Sciences Corporation, Manassas, Virginia, was a unique aircraft flown at NASA's Dryden Flight Research Center, Edwards, California, under a cooperative agreement between NASA and Aurora. Dryden hosted the Theseus program, providing hangar space and range safety for flight testing. Aurora Flight Sciences was responsible for the actual flight testing, vehicle flight safety, and operation of the aircraft. The Theseus remotely piloted aircraft flew its maiden flight on May 24, 1996, at Dryden. During its sixth flight on November 12, 1996, Theseus experienced an in-flight structural failure that resulted in the loss of the aircraft. As of the beginning of the year 2000, Aurora had not rebuilt the aircraft. Theseus was built for NASA under an innovative, $4.9 million fixed-price contract by Aurora Flight Sciences Corporation and its partners, West Virginia University, Morgantown, West Virginia, and Fairmont State College, Fairmont, West Virginia. The twin-engine, unpiloted vehicle had a 140-foot wingspan, and was constructed largely of composite materials. Powered by two 80-horsepower, turbocharged piston engines that drove twin 9-foot-diameter propellers, Theseus was designed to fly autonomously at high altitudes, with takeoff and landing under the active control of a ground-based pilot in a ground control station 'cockpit.' With the potential ability to carry 700 pounds of science instruments to altitudes above 60,000 feet for durations of greater than 24 hours, Theseus was intended to support research in areas such as stratospheric ozone depletion and the atmospheric effects of future high-speed civil transport aircraft engines. Instruments carried aboard Theseus also would be able to validate satellite-based global environmental change measurements. Dryden

  5. The calculated effect of various hydrodynamic and aerodynamic factors on the take-off of a large flying boat

    NASA Technical Reports Server (NTRS)

    Olson, R E; Allison, J M

    1940-01-01

    Report presents the results of an investigation made to determine the influence of various factors on the take-off performance of a hypothetical large flying boat by means of take-off calculations. The factors varied in the calculations were size of hull (load coefficient), wing setting, trim, deflection of flap, wing loading, aspect ratio, and parasite drag. The take-off times and distances were calculated to the stalling speeds and the performance above these speeds was separately studied to determine piloting technique for optimum take-off.

  6. Transition from wing to leg forces during landing in birds.

    PubMed

    Provini, Pauline; Tobalske, Bret W; Crandell, Kristen E; Abourachid, Anick

    2014-08-01

    Transitions to and from the air are critical for aerial locomotion and likely shaped the evolution of flying animals. Research on take-off demonstrates that legs generate greater body accelerations compared with wings, and thereby contribute more to initial flight velocity. Here, we explored coordination between wings and legs in two species with different wingbeat styles, and quantified force production of these modules during the final phase of landing. We used the same birds that we had previously studied during take-off: zebra finch (Taeniopygia guttata, N=4) and diamond dove (Geopelia cuneata, N=3). We measured kinematics using high-speed video, aerodynamics using particle image velocimetry, and ground-reaction forces using a perch mounted on a force plate. In contrast with the first three wingbeats of take-off, the final four wingbeats during landing featured ~2 times greater force production. Thus, wings contribute proportionally more to changes in velocity during the last phase of landing compared with the initial phase of take-off. The two species touched down at the same velocity (~1 m s(-1)), but they exhibited significant differences in the timing of their final wingbeat relative to touchdown. The ratio of average wing force to peak leg force was greater in diamond doves than in zebra finches. Peak ground reaction forces during landing were ~50% of those during take-off, consistent with the birds being motivated to control landing. Likewise, estimations of mechanical energy flux for both species indicate that wings produce 3-10 times more mechanical work within the final wingbeats of flight compared with the kinetic energy of the body absorbed by legs during ground contact. © 2014. Published by The Company of Biologists Ltd.

  7. Vertical and Horizontal Impact Force Comparison During Jump Landings With and Without Rotation in NCAA Division I Male Soccer Players.

    PubMed

    Harry, John R; Barker, Leland A; Mercer, John A; Dufek, Janet S

    2017-07-01

    Harry, JR, Barker, LA, Mercer, JA, and Dufek, JS. Vertical and horizontal impact force comparison during jump landings with and without rotation in NCAA Division I male soccer players. J Strength Cond Res 31(7): 1780-1786, 2017-There is a wealth of research on impact force characteristics when landing from a jump. However, there are no data on impact forces during landing from a jump with an airborne rotation about the vertical axis. We examined impact force parameters in the vertical and horizontal axes during vertical jump (VJ) landings and VJ landings with a 180° rotation (VJR). Twenty-four Division I male soccer players performed 3 VJ and VJR landings on a dual-force platform system. Paired-samples t-tests (α = 0.05) compared differences in the first (F1) and second (F2) peak vertical ground reaction forces, times to F1 (tF1), F2 (tF2), and the end of the impact phase, vertical impulse, and anterior-posterior and medial-lateral force couples. Effect sizes (ES; large >0.8) were computed to determine the magnitude of the differences. Lower jump height (41.60 ± 4.03 cm, VJ landings; 39.40 ± 4.05 cm, VJR landings; p = 0.002; ES = 0.39), greater F2 (55.71 ± 11.95 N·kg, VJ; 68.16 ± 14.82 N·kg; p < 0.001; ES = 0.94), faster tF2 (0.057 ± 0.012 seconds, VJ; 0.047 ± 0.011 seconds, VJR; p = 0.001; ES = 0.89), greater anterior-posterior (0.06 ± 0.03 N·s·kg, VJ; 0.56 ± 0.15 N·s·kg, VJR; p < 0.001; ES = 1.83) and medial-lateral force couples (0.29 ± 0.11 N·s·kg, VJ; 0.56 ± 0.14 N·s·kg, VJR; p < 0.001; ES = 1.46) occurred during VJR landings. No other differences were identified. This kinetic analysis determined that landing from a jump with 180° airborne rotation is different than landing from a jump without an airborne rotation. Male Division I soccer players could benefit from increasing the volume of VJR landings during training to address the differences in jump height and force parameters compared with VJ landings.

  8. Kinetic and kinematic differences between first and second landings of a drop vertical jump task: implications for injury risk assessments.

    PubMed

    Bates, Nathaniel A; Ford, Kevin R; Myer, Gregory D; Hewett, Timothy E

    2013-04-01

    Though the first landing of drop vertical jump task is commonly used to assess biomechanical performance measures that are associated with anterior cruciate ligament injury risk in athletes, the implications of the second landing in this task have largely been ignored. We examined the first and second landings of a drop vertical jump for differences in kinetic and kinematic behaviors at the hip and knee. A cohort of 239 adolescent female basketball athletes (age=13.6 (1.6) years) completed drop vertical jump tasks from an initial height of 31 cm. A three dimensional motion capture system recorded positional data while dual force platforms recorded ground reaction forces for each trial. The first landing demonstrated greater hip adduction angle, knee abduction angle, and knee abduction moment than the second landing (P-values<0.028). The second landing demonstrated smaller flexion angles and moments at the hip and knee than the first landing (P-values<0.035). The second landing also demonstrated greater side-to-side asymmetry in hip and knee kinematics and kinetics for both the frontal and sagittal planes (P-values<0.044). The results have important implications for the future use of the drop vertical jump as an assessment tool for anterior cruciate ligament injury risk behaviors in adolescent female athletes. The second landing may be a more rigorous task and provides a superior tool to evaluate sagittal plane risk factors than the first landing, which may be better suited to evaluate frontal plane risk factors. Copyright © 2013 Elsevier Ltd. All rights reserved.

  9. Kinetic and kinematic differences between first and second landings of a drop vertical jump task: Implications for injury risk assessments✩

    PubMed Central

    Bates, Nathaniel A.; Ford, Kevin R.; Myer, Gregory D.; Hewett, Timothy E.

    2013-01-01

    Background Though the first landing of drop vertical jump task is commonly used to assess biomechanical performance measures that are associated with anterior cruciate ligament injury risk in athletes, the implications of the second landing in this task have largely been ignored. We examined the first and second landings of a drop vertical jump for differences in kinetic and kinematic behaviors at the hip and knee. Methods Acohort of 239 adolescent female basketball athletes (age = 13.6 (1.6) years) completed drop vertical jump tasks from an initial height of 31 cm. A three dimensional motion capture system recorded positional data while dual force platforms recorded ground reaction forces for each trial. Findings The first landing demonstrated greater hip adduction angle, knee abduction angle, and knee abduction moment than the second landing (P-values < 0.028). The second landing demonstrated smaller flexion angles and moments at the hip and knee than the first landing (P-values < 0.035). The second landing also demonstrated greater side-to-side asymmetry in hip and knee kinematics and kinetics for both the frontal and sagittal planes (P-values < 0.044). Interpretation The results have important implications for the future use of the drop vertical jump as an assessment tool for anterior cruciate ligament injury risk behaviors in adolescent female athletes. The second landing may be a more rigorous task and provides a superior tool to evaluate sagittal plane risk factors than the first landing, which may be better suited to evaluate frontal plane risk factors. PMID:23562293

  10. Impact of landuse/land cover change on run-off in the catchment of a hydro power project

    NASA Astrophysics Data System (ADS)

    Khare, Deepak; Patra, Diptendu; Mondal, Arun; Kundu, Sananda

    2017-05-01

    The landuse/land cover change and rainfall have a significant influence on the hydrological response of the river basins. The run-off characteristics are changing naturally due to reduction of initial abstraction that increases the run-off volume. Therefore, it is necessary to quantify the changes in the run-off characteristics of a catchment under the influence of changed landuse/land cover. Soil conservation service model has been used in the present study to analyse the impact of various landuse/land cover (past, present and future time period) change in the run-off characteristics of a part of Narmada basin at the gauge discharge site of Mandaleswar in Madhya Pradesh, India. Calculated run-off has been compared with the observed run-off data for the study. The landuse/land cover maps of 1990, 2000 and 2009 have been prepared by digital classification method with proper accuracy using satellite imageries. The impact of the run-off change on hydro power potential has been assessed in the study along with the estimation of the future changes in hydro power potential. Five types of conditions (+10, +5 %, average, -5, -10 % of average rainfall) have been applied with 90 and 75 % dependability status. The generated energy will be less in 90 % dependable flow in respect to the 75 % dependable flow. This work will be helpful for future planning related to establishment of hydropower setup.

  11. Vertical Descent and Landing Tests of a 0.13-Scale Model of the Convair XFY-1 Vertically Rising Airplane in Still Air, TED No. NACA DE 368

    NASA Technical Reports Server (NTRS)

    Smith, Charlee C., Jr.; Lovell, Powell M., Jr.

    1954-01-01

    An investigation is being conducted to determine the dynamic stability and control characteristics of a 0.13-scale flying model of Convair XFY-1 vertically rising airplane. This paper presents the results of flight and force tests to determine the stability and control characteristics of the model in vertical descent and landings in still air. The tests indicated that landings, including vertical descent from altitudes representing up to 400 feet for the full-scale airplane and at rates of descent up to 15 or 20 feet per second (full scale), can be performed satisfactorily. Sustained vertical descent in still air probably will be more difficult to perform because of large random trim changes that become greater as the descent velocity is increased. A slight steady head wind or cross wind might be sufficient to eliminate the random trim changes.

  12. Thrust Augmentation Study of Cross-Flow Fan for Vertical Take-Off and Landing Aircraft

    DTIC Science & Technology

    2012-09-01

    configuration by varying the gap between the CFFs. Computational fluid simulations of the dual CFF configuration was performed using ANSYS CFX to find the...Computational fluid simulations of the dual CFF configuration was performed using ANSYS CFX to find the thrust generated as well as the optimal operating point...RECOMMENDATIONS ...............................................................................43 APPENDIX A. ANSYS CFX SETTINGS FOR DUAL CFF (8,000

  13. Integration of Twenty-Bladed Cross-Flow Fan into Vertical Take-Off and Landing Aircraft

    DTIC Science & Technology

    2013-06-01

    a new 20-bladed rotor was designed in SolidWorks and imported into ANSYS - CFX , which was used to analytically determine the thrust generated at speeds...implementation and experimentation. To accomplish this task, a new 20-bladed rotor was designed in SolidWorks and imported into ANSYS - CFX , which was...11 4. ANSYS - CFX CFD Analysis

  14. Gender variability in electromyographic activity, in vivo behaviour of the human gastrocnemius and mechanical capacity during the take-off phase of a countermovement jump.

    PubMed

    Rubio-Arias, Jacobo Ángel; Ramos-Campo, Domingo Jesús; Peña Amaro, José; Esteban, Paula; Mendizábal, Susana; Jiménez, José Fernando

    2017-11-01

    The purpose of this study was to analyse gender differences in neuromuscular behaviour of the gastrocnemius and vastus lateralis during the take-off phase of a countermovement jump (CMJ), using direct measures (ground reaction forces, muscle activity and dynamic ultrasound). Sixty-four young adults (aged 18-25 years) participated voluntarily in this study, 35 men and 29 women. The firing of the trigger allowed obtainment of data collection vertical ground reaction forces (GRF), surface electromyography activity (sEMG) and dynamic ultrasound gastrocnemius of both legs. Statistically significant gender differences were observed in the jump performance, which appear to be based on differences in muscle architecture and the electrical activation of the gastrocnemius muscles and vastus lateralis. So while men developed greater peak power, velocity take-offs and jump heights, jump kinetics compared to women, women also required a higher electrical activity to develop lower power values. Additionally, the men had higher values pennation angles and muscle thickness than women. Men show higher performance of the jump test than women, due to significant statistical differences in the values of muscle architecture (pennation angle and thickness muscle), lower Neural Efficiency Index and a higher amount of sEMG activity per second during the take-off phase of a CMJ. © 2016 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  15. High-quality vertical light emitting diodes fabrication by mechanical lift-off technique

    NASA Astrophysics Data System (ADS)

    Tu, Po-Min; Hsu, Shih-Chieh; Chang, Chun-Yen

    2011-10-01

    We report the fabrication of mechanical lift-off high quality thin GaN with Hexagonal Inversed Pyramid (HIP) structures for vertical light emitting diodes (V-LEDs). The HIP structures were formed at the GaN/sapphire substrate interface under high temperature during KOH wet etching process. The average threading dislocation density (TDD) was estimated by transmission electron microscopy (TEM) and found the reduction from 2×109 to 1×108 cm-2. Raman spectroscopy analysis revealed that the compressive stress of GaN epilayer was effectively relieved in the thin-GaN LED with HIP structures. Finally, the mechanical lift-off process is claimed to be successful by using the HIP structures as a sacrificial layer during wafer bonding process.

  16. Human Ocular Counter-Rolling and Roll Tilt Perception during Off-Vertical Axis Rotation after Spaceflight

    NASA Technical Reports Server (NTRS)

    Clement, Gilles; Denise, Pierre; Reschke, Millard; Wood, Scott J.

    2007-01-01

    Ocular counter-rolling (OCR) induced by whole body tilt in roll has been explored after spaceflight as an indicator of the adaptation of the otolith function to microgravity. It has been claimed that the overall pattern of OCR responses during static body tilt after spaceflight is indicative of a decreased role of the otolith function, but the results of these studies have not been consistent, mostly due to large variations in the OCR within and across individuals. By contrast with static head tilt, off-vertical axis rotation (OVAR) presents the advantage of generating a sinusoidal modulation of OCR, allowing averaged measurements over several cycles, thus improving measurement accuracy. Accordingly, OCR and the sense of roll tilt were evaluated in seven astronauts before and after spaceflight during OVAR at 45 /s in darkness at two angles of tilt (10 and 20 ). There was no significant difference in OCR during OVAR immediately after landing compared to preflight. However, the amplitude of the perceived roll tilt during OVAR was significantly larger immediately postflight, and then returned to control values in the following days. Since the OCR response is predominantly attributed to the shearing force exerted on the utricular macula, the absence of change in OCR postflight suggests that the peripheral otolith organs function normally after short-term spaceflight. However, the increased sense of roll tilt indicates an adaptation in the central processing of gravitational input, presumably related to a re-weigthing of the internal representation of gravitational vertical as a result of adaptation to microgravity.

  17. Compound Wing Vertical Takeoff and Landing Small Unmanned Aircraft System

    NASA Technical Reports Server (NTRS)

    Logan, Michael J. (Inventor); Motter, Mark A. (Inventor); Deloach, Richard (Inventor); Vranas, Thomas L. (Inventor); Prendergast, Joseph M. (Inventor); Lipp, Brittney N. (Inventor)

    2017-01-01

    Systems, methods, and devices are provided that enable robust operations of a small unmanned aircraft system (sUAS) using a compound wing. The various embodiments may provide a sUAS with vertical takeoff and landing capability, long endurance, and the capability to operate in adverse environmental conditions. In the various embodiments a sUAS may include a fuselage and a compound wing comprising a fixed portion coupled to the fuselage, a wing lifting portion outboard of the fixed portion comprising a rigid cross member and a controllable articulating portion configured to rotate controllable through a range of motion from a horizontal position to a vertical position, and a freely rotating wing portion outboard of the wing lifting portion and configured to rotate freely based on wind forces incident on the freely rotating wing portion.

  18. Snowboard Jumping, Newton's Second Law and the Force on Landing

    ERIC Educational Resources Information Center

    O'Shea, Michael J.

    2004-01-01

    An application of Newton's second law to a snowboarder dropping off a vertical ledge shows that the average normal force during landing (force exerted by the ground on the snowboarder) is determined by four factors. It is shown that the flexing of the legs, the softness of the snow, the angle of the landing surface and the forward motion of the…

  19. Natural substrate lift-off technique for vertical light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Lee, Chia-Yu; Lan, Yu-Pin; Tu, Po-Min; Hsu, Shih-Chieh; Lin, Chien-Chung; Kuo, Hao-Chung; Chi, Gou-Chung; Chang, Chun-Yen

    2014-04-01

    Hexagonal inverted pyramid (HIP) structures and the natural substrate lift-off (NSLO) technique were demonstrated on a GaN-based vertical light-emitting diode (VLED). The HIP structures were formed at the interface between GaN and the sapphire substrate by molten KOH wet etching. The threading dislocation density (TDD) estimated by transmission electron microscopy (TEM) was reduced to 1 × 108 cm-2. Raman spectroscopy indicated that the compressive strain from the bottom GaN/sapphire was effectively released through the HIP structure. With the adoption of the HIP structure and NSLO, the light output power and yield performance of leakage current could be further improved.

  20. Airport take-off noise assessment aimed at identify responsible aircraft classes.

    PubMed

    Sanchez-Perez, Luis A; Sanchez-Fernandez, Luis P; Shaout, Adnan; Suarez-Guerra, Sergio

    2016-01-15

    Assessment of aircraft noise is an important task of nowadays airports in order to fight environmental noise pollution given the recent discoveries on the exposure negative effects on human health. Noise monitoring and estimation around airports mostly use aircraft noise signals only for computing statistical indicators and depends on additional data sources so as to determine required inputs such as the aircraft class responsible for noise pollution. In this sense, the noise monitoring and estimation systems have been tried to improve by creating methods for obtaining more information from aircraft noise signals, especially real-time aircraft class recognition. Consequently, this paper proposes a multilayer neural-fuzzy model for aircraft class recognition based on take-off noise signal segmentation. It uses a fuzzy inference system to build a final response for each class p based on the aggregation of K parallel neural networks outputs Op(k) with respect to Linear Predictive Coding (LPC) features extracted from K adjacent signal segments. Based on extensive experiments over two databases with real-time take-off noise measurements, the proposed model performs better than other methods in literature, particularly when aircraft classes are strongly correlated to each other. A new strictly cross-checked database is introduced including more complex classes and real-time take-off noise measurements from modern aircrafts. The new model is at least 5% more accurate with respect to previous database and successfully classifies 87% of measurements in the new database. Copyright © 2015 Elsevier B.V. All rights reserved.

  1. [Experimental study on single-electrode metal detector for taking off foreign bodies from the swine].

    PubMed

    Wang, Li-Gang; Zhang, Gen-Min

    2010-06-01

    To study the practicability of single-electrode metal detector by using it to take off foreign bodies from swine. The single-electrode metal detector was invented based on the theory of complementary oscillator. Twelve extremities were obtained from 3 Minnesota-Hormel stains 7-month old male swine. All the extremities were divided into 3 groups: lump metal foreign bodies were planted in group A, needle shape metal foreign bodies were planted in group B, and sand shapd metal foreign bodies were planted in group C. The self-invented single-electrode metal detector was used to take off these foreign bodies, and the taking times were recorded. After the operation, the X-ray was used to examine if the foreign bodies were still in the extremities of the swine. The foreign bodies were taken off completely in the 3 groups, and the average time were 38 s, 3 min and 12 s, and 3 min and 59 s respectively. The X-ray examination confirmed that the detector could take off the foreign bodies completely. This detector has satisfactory effect in animal experiment, which could detect and extract metal foreign bodies quickly and exactly without X-ray help duration the operation, and can be used in clinical cases secondly.

  2. Vertical view Apollo 16 Descartes landing sites as photographed by Apollo 14

    NASA Technical Reports Server (NTRS)

    1972-01-01

    An almost vertical view of the Apollo 16 Descartes landing sites as photographed from the Apollo 14 spacecraft. Overlays are provided to point out extravehicular activity (EVA), Lunar Roving Vehicle (LRV) travers routes and the nicknames of features. The Roman numerals indicate the EVA numbers and the Arabic numbers point out stations or traverse stops.

  3. Evaluation of radiocaesium wash-off by soil erosion from various land uses using USLE plots.

    PubMed

    Yoshimura, Kazuya; Onda, Yuichi; Kato, Hiroaki

    2015-01-01

    Radiocaesium wash-off associated with soil erosion in different land use was monitored using USLE plots in Kawamata, Fukushima Prefecture, Japan after the Fukushima Dai-ichi Nuclear Power Plant accident. Parameters and factors relating to soil erosion and (137)Cs concentration in the eroded soil were evaluated based on the field monitoring and presented. The erosion of fine soil, which is defined as the fraction of soil overflowed along with discharged water from a sediment-trap tank, constituted a large proportion of the discharged radiocaesium. This indicated that the quantitative monitoring of fine soil erosion is greatly important for the accurate evaluation of radiocaesium wash-off. An exponential relationship was found between vegetation cover and the amount of eroded soil. Moreover, the radiocaesium concentrations in the discharged soil were greatly affected by the land use. These results indicate that radiocaesium wash-off related to vegetation cover and land use is crucially important in modelling radiocaesium migration. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. A guidance and control assessment of three vertical landing options for RLV

    NASA Technical Reports Server (NTRS)

    Gallaher, M.; Coughlin, D.; Krupp, D

    1995-01-01

    The National Aeronautics and Space Administration is considering a vertical lander as a candidate concept for a single-stage-to-orbit reusable launch vehicle (RLV). Three strategies for guiding and controlling the inversion of a reentering RLV from a nose-first attitude to a vertical landing attitude are suggested. Each option is simulated from a common reentry state to touchdown, using a common guidance algorithm and different controllers. Results demonstrate the characteristics that typify and distinguish each concept and help to identify peculiar problems, level of guidance and control sophistication required, feasibility concerns, and areas in which stringent subsystem requirements will be imposed by guidance and control.

  5. Considering land-sea interactions and trade-offs for food and biodiversity.

    PubMed

    Cottrell, Richard S; Fleming, Aysha; Fulton, Elizabeth A; Nash, Kirsty L; Watson, Reg A; Blanchard, Julia L

    2018-02-01

    With the human population expected to near 10 billion by 2050, and diets shifting towards greater per-capita consumption of animal protein, meeting future food demands will place ever-growing burdens on natural resources and those dependent on them. Solutions proposed to increase the sustainability of agriculture, aquaculture, and capture fisheries have typically approached development from single sector perspectives. Recent work highlights the importance of recognising links among food sectors, and the challenge cross-sector dependencies create for sustainable food production. Yet without understanding the full suite of interactions between food systems on land and sea, development in one sector may result in unanticipated trade-offs in another. We review the interactions between terrestrial and aquatic food systems. We show that most of the studied land-sea interactions fall into at least one of four categories: ecosystem connectivity, feed interdependencies, livelihood interactions, and climate feedback. Critically, these interactions modify nutrient flows, and the partitioning of natural resource use between land and sea, amid a backdrop of climate variability and change that reaches across all sectors. Addressing counter-productive trade-offs resulting from land-sea links will require simultaneous improvements in food production and consumption efficiency, while creating more sustainable feed products for fish and livestock. Food security research and policy also needs to better integrate aquatic and terrestrial production to anticipate how cross-sector interactions could transmit change across ecosystem and governance boundaries into the future. © 2017 John Wiley & Sons Ltd.

  6. Explosive lower limb extension mechanics: An on-land vs. in-water exploratory comparison.

    PubMed

    Guignard, Brice; Lauer, Jessy; Samozino, Pierre; Mourão, Luis; Vilas-Boas, João Paulo; Rouard, Annie Hélène

    2017-12-08

    During a horizontal underwater push-off, performance is strongly limited by the presence of water, inducing resistances due to its dense and viscous nature. At the same time, aquatic environments offer a support to the swimmer with the hydrostatic buoyancy counteracting the effects of gravity. Squat jump is a vertical terrestrial push-off with a maximal lower limb extension limited by the gravity force, which attracts the body to the ground. Following this observation, we characterized the effects of environment (water vs. air) on the mechanical characteristics of the leg push-off. Underwater horizontal wall push-off and vertical on-land squat jumps of two local swimmers were evaluated with force plates, synchronized with a lateral camera. To better understand the resistances of the aquatic movement, a quasi-steady Computational Fluid Dynamics (CFD) analysis was performed. The force-, velocity- and power-time curves presented similarities in both environments corresponding to a proximo-distal joints organization. In water, swimmers developed a three-step explosive rise of force, which the first one mainly related to the initiation of body movement. Drag increase, which was observed from the beginning to the end of the push-off, related to the continuous increase of body velocity with high values of drag coefficient (C D ) and frontal areas before take-off. Specifically, with velocity, frontal area was the main drag component to explain inter-individual differences, suggesting that the streamlined position of the lower limbs is decisive to perform an efficient push-off. This study motivates future CFD simulations under more ecological, unsteady conditions. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Modeling human vestibular responses during eccentric rotation and off vertical axis rotation

    NASA Technical Reports Server (NTRS)

    Merfeld, D. M.; Paloski, W. H. (Principal Investigator)

    1995-01-01

    A mathematical model has been developed to help explain human multi-sensory interactions. The most important constituent of the model is the hypothesis that the nervous system incorporates knowledge of sensory dynamics into an "internal model" of these dynamics. This internal model allows the nervous system to integrate the sensory information from many different sensors into a coherent estimate of self-motion. The essence of the model is unchanged from a previously published model of monkey eye movement responses; only a few variables have been adjusted to yield the prediction of human responses. During eccentric rotation, the model predicts that the axis of eye rotation shifts slightly toward alignment with gravito-inertial force. The model also predicts that the time course of the perception of tilt following the acceleration phase of eccentric rotation is much slower than that during deceleration. During off vertical axis rotation (OVAR) the model predicts a small horizontal bias along with small horizontal, vertical, and torsional oscillations. Following OVAR stimulation, when stopped right- or left-side down, a small vertical component is predicted that decays with the horizontal post-rotatory response. All of the predictions are consistent with measurements of human responses.

  8. Trajectory optimization for lunar rover performing vertical takeoff vertical landing maneuvers in the presence of terrain

    NASA Astrophysics Data System (ADS)

    Ma, Lin; Wang, Kexin; Xu, Zuhua; Shao, Zhijiang; Song, Zhengyu; Biegler, Lorenz T.

    2018-05-01

    This study presents a trajectory optimization framework for lunar rover performing vertical takeoff vertical landing (VTVL) maneuvers in the presence of terrain using variable-thrust propulsion. First, a VTVL trajectory optimization problem with three-dimensional kinematics and dynamics model, boundary conditions, and path constraints is formulated. Then, a finite-element approach transcribes the formulated trajectory optimization problem into a nonlinear programming (NLP) problem solved by a highly efficient NLP solver. A homotopy-based backtracking strategy is applied to enhance the convergence in solving the formulated VTVL trajectory optimization problem. The optimal thrust solution typically has a "bang-bang" profile considering that bounds are imposed on the magnitude of engine thrust. An adaptive mesh refinement strategy based on a constant Hamiltonian profile is designed to address the difficulty in locating the breakpoints in the thrust profile. Four scenarios are simulated. Simulation results indicate that the proposed trajectory optimization framework has sufficient adaptability to handle VTVL missions efficiently.

  9. On the relationship between lower extremity muscles activation and peak vertical and posterior ground reaction forces during single leg drop landing.

    PubMed

    Mahaki, M; Mi'mar, R; Mahaki, B

    2015-10-01

    Anterior cruciate ligament (ACL) injury continues to be an important medical issue for athletes participating in sports. Vertical and posterior ground reaction forces have received considerable attention for their potential influence on ACL injuries. The purpose of this study was to examine the relationship between electromyographic activity of lower extremity muscles and the peak vertical and posterior ground reaction forces during single leg drop landing. Thirteen physical education male students participated in this correlation study. Electromyographic activities of gluteus medius, biceps femoris, medial gastrocnemius, soleus as well as anterior tibialis muscles along with ground reaction forces were measured. Participants performed single-leg landing from a 0.3 m height on to a force platform. Landing was divided into two phases: 100 ms preceding ground contact and 100 ms proceeding ground contact. Pearson correlation test was used to determine the relationships between these muscles activity and peak vertical and posterior ground reaction forces. The results of the study indicated that the activity of soleus and tibialis anterior in pre-landing phase were positively correlated with peak vertical ground reaction force ([P≤0.04], [P≤0.008], respectively). However, no significant correlation was found between the activities of other muscles in pre-landing phase and peak vertical as well as peak posterior ground reaction forces. Also, no significant correlation was found between the activities of muscles in post-landing phase and peak vertical as well as peak posterior ground reaction forces. Soleus loading shifts the proximal tibia posterior at the knee joint and tibialis anterior prevent hyperporonation of the ankle, a mechanisms of ACL injury. Hence, neuromuscular training promoting preparatory muscle activity in these muscles may reduce the incidence of ACL injuries.

  10. Evaluation of Lands for Off-Road Recreational Four-Wheel Drive Vehicle Use

    DTIC Science & Technology

    1981-10-01

    21. Hoover, Bob, "Off-Road Vehicle Problem on Public Lands," Proceedings of the 40th Annual Meeting of the Association of Midwest Fish and Wildlife...Trailbike Recreation (U.S. Department of the Interior, Heritage Chonservation and RecreatiýFService, 1978). Planting and Establishment of Trees, Shrubs ...Ground Covers and Vines , TM 5-E3U-4 (DA, 15 June 1976). Pleuther, R. L., A Critique on the Performance of Off-Road Vehicles: Full Scale Test Results

  11. Predicting vertical jump height from bar velocity.

    PubMed

    García-Ramos, Amador; Štirn, Igor; Padial, Paulino; Argüelles-Cienfuegos, Javier; De la Fuente, Blanca; Strojnik, Vojko; Feriche, Belén

    2015-06-01

    The objective of the study was to assess the use of maximum (Vmax) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s(-2)). Vertical jump height was calculated from the take-off velocity (Vtake-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r(2) = 0.307), while the differences between Vmax and Vtake-off were homogenously distributed (r(2) = 0.071). These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine. Key pointsVertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer.The relationship between the point at which bar acceleration is less than -9.81 m·s(-2) and the real take-off is affected by the velocity of movement.Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance.

  12. Predicting Vertical Jump Height from Bar Velocity

    PubMed Central

    García-Ramos, Amador; Štirn, Igor; Padial, Paulino; Argüelles-Cienfuegos, Javier; De la Fuente, Blanca; Strojnik, Vojko; Feriche, Belén

    2015-01-01

    The objective of the study was to assess the use of maximum (Vmax) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s-2). Vertical jump height was calculated from the take-off velocity (Vtake-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r2 = 0.307), while the differences between Vmax and Vtake-off were homogenously distributed (r2 = 0.071). These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine. Key points Vertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer. The relationship between the point at which bar acceleration is less than -9.81 m·s-2 and the real take-off is affected by the velocity of movement. Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance. PMID:25983572

  13. Coastal Vertical Land motion in the German Bight

    NASA Astrophysics Data System (ADS)

    Becker, Matthias; Fenoglio, Luciana; Reckeweg, Florian

    2017-04-01

    In the framework of the ESA Sea Level Climate Change Initiative (CCI) we analyse a set of GNSS equipped tide gauges at the German Bight. Main goals are the determination of tropospheric zenith delay corrections for altimetric observations, precise coordinates in ITRF2008 and vertical land motion (VLM) rates of the tide gauge stations. These are to be used for georeferencing the tide gauges and the correction of tide gauge observations for VLM. The set of stations includes 38 GNSS stations. 19 stations are in the German Bight, where 15 of them belong to the Bundesanstalt für Gewässerkunde, 3 to EUREF and 1 to GREF. These stations are collocated with tide gauges (TGs). The other 19 GNSS stations in the network belong to EUREF, IGS and GREF. We analyse data in the time span from 2008 till the end of 2016 with the Bernese PPP processing approach. Data are partly rather noisy and disturbed by offsets and data gaps at the coastal TG sites. Special effort is therefore put into a proper estimation of the VLM. We use FODITS (Ostini2012), HECTOR (Bos et al, 2013), CATS (Williams, 2003) and the MIDAS approach of Blewitt (2016) to robustly derive rates and realistic error estimates. The results are compared to those published by the European Permanent Network (EPN), ITRF and the Système d'Observation du Niveau des Eaux Littorales (SONEL) for common stations. Vertical motion is small in general, at the -1 to -2 mm/yr level for most coastal stations. A comparison of the standard deviations of the velocity differences to EPN with the mean values of the estimated velocity standard deviations for our solution shows a very good agreement of the estimated velocities and their standard deviations with the reference solution from EPN. In the comparison with results by SONEL the standard deviation of the differences is slightly higher. The discrepancies may arise from differences in the time span analyzed and gaps, offsets and data preprocessing. The combined estimation of functional

  14. Pesticides and passive dispersal: acaricide- and starvation-induced take-off of the predatory mite Neoseiulus baraki.

    PubMed

    Monteiro, Vaneska Barbosa; Silva, Vanessa Farias; Lima, Debora Barbosa; Guedes, Raul Narciso Carvalho; Gondim, Manoel Guedes Correa

    2018-06-01

    An understanding of the causes and consequences of dispersal is vital for managing populations. Environmental contaminants, such as pesticides, provide potential environmental context-dependent stimuli for dispersal of targeted and non-targeted species, which may occur not only for active but also for passive dispersal, although such a possibility is frequently neglected. Here, we assessed the potential of food deprivation and acaricides to interfere with the take-off for passive (wind) dispersal of the predatory mite Neoseiulus baraki. Wind tunnel bioassays indicated that starvation favoured the take-off for wind dispersal by the mite predator, which also varied with wind velocity, and dispersal increased at higher velocities within the 1-7 (m s -1 ) range tested. For the acaricides tested, particularly the biopesticide azadirachtin but also abamectin and fenpyroximate, the rate of predator take-off for dispersal increased, and further increased with wind velocity up to 7 m/s. Such responses were associated with changes in the predator behavioural preparation for wind-mediated passive dispersal, with a greater incidence of the standing posture that permitted take-off. The rate of take-off for passive dispersal by N. baraki increased with food deprivation and exposure to the residues of agricultural acaricides. Azadirachtin exposure resulted in a particularly strong response, although abamectin and fenpyroximate also stimulated dispersal. © 2018 Society of Chemical Industry. © 2018 Society of Chemical Industry.

  15. Trade-offs in water and carbon ecosystem services with land-use changes in grasslands.

    PubMed

    Kim, John H; Jobbágy, Esteban G; Jackson, Robert B

    2016-09-01

    Increasing pressures for food, fiber, and fuel continue to drive global land-use changes. Efforts to optimize ecosystem services under alternative land uses are often hampered by the complex interactions and trade-offs among them. We examined the effects of land-use changes on ecosystem carbon storage and groundwater recharge in grasslands of Argentina and the United States to (1) understand the relationships between both services, (2) predict their responses to vegetation shifts across environmental gradients, and (3) explore how market or policy incentives for ecosystem services could affect land-use changes. A trade-off of ecosystem services was evident in most cases, with woody encroachment increasing carbon storage (+29 Mg C/ha) but decreasing groundwater recharge (-7.3 mm/yr) and conversions to rain-fed cultivation driving opposite changes (-32 Mg C/ha vs. +13 mm/yr). In contrast, crops irrigated with ground water tended to reduce both services compared to the natural grasslands they replaced. Combining economic values of the agricultural products together with the services, we highlight potentials for relatively modest financial incentives for ecosystem services to abate land-use changes and for incentives for carbon to drive land-use decisions over those of water. Our findings also identify key opportunities and caveats for some win-win and lose-lose land-use changes for more integrative and sustainable strategies for land management. © 2016 by the Ecological Society of America.

  16. Assessing land take by urban development and its impact on carbon storage: Findings from two case studies in Italy

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

    Sallustio, L.; Quatrini, V.; Geneletti, D., E-mail: davide.geneletti@unitn.it

    Highlights: • We tested a new methodology for monitoring land take and its effects on C storage. • The ecological impact of urban growth derives from the previous land use. • C loss increases with the naturalness of the territory. • Different urban assets may imply different forms of land take containment. Land take due to urbanization triggers a series of negative environmental impacts with direct effects on quality of life for people living in cities. Changes in ecosystem services are associated with land take, among which is the immediate C loss due to land use conversion. Land use changemore » monitoring represents the first step in quantifying land take and its drivers and impacts. To this end, we propose an innovative methodology for monitoring land take and its effects on ecosystem services (in particular, C loss) under multi-scale contexts. The devised approach was tested in two areas with similar sizes, but different land take levels during the time-span 1990–2008 in Central Italy (the Province of Rome and the Molise Region). The estimates of total coverage of built up areas were calculated using point sampling. The area of the urban patches including each sampling point classified as built up areas in the year 1990 and/or in the year 2008 is used to estimate total abundance and average area of built up areas. Biophysical and economic values for carbon loss associated with land take were calculated using InVEST. Although land take was 7–8 times higher in the Province of Rome (from 15.1% in 1990 to 20.4% in 2008) than in Molise region, our findings show that its relative impact on C storage is higher in the latter, where the urban growth consistently affects not only croplands but also semi-natural land uses such as grasslands and other wooded lands. The total C loss due to land take has been estimated in 1.6 million Mg C, corresponding to almost 355 million €. Finally, the paper discusses the main characteristics of urban growth and their

  17. Three-dimensional organization of vestibular-related eye movements to off-vertical axis rotation and linear translation in pigeons

    NASA Technical Reports Server (NTRS)

    Dickman, J. D.; Angelaki, D. E.

    1999-01-01

    During linear accelerations, compensatory reflexes should continually occur in order to maintain objects of visual interest as stable images on the retina. In the present study, the three-dimensional organization of the vestibulo-ocular reflex in pigeons was quantitatively examined during linear accelerations produced by constant velocity off-vertical axis yaw rotations and translational motion in darkness. With off-vertical axis rotations, sinusoidally modulated eye-position and velocity responses were observed in all three components, with the vertical and torsional eye movements predominating the response. Peak torsional and vertical eye positions occurred when the head was oriented with the lateral visual axis of the right eye directed orthogonal to or aligned with the gravity vector, respectively. No steady-state horizontal nystagmus was obtained with any of the rotational velocities (8-58 degrees /s) tested. During translational motion, delivered along or perpendicular to the lateral visual axis, vertical and torsional eye movements were elicited. No significant horizontal eye movements were observed during lateral translation at frequencies up to 3 Hz. These responses suggest that, in pigeons, all linear accelerations generate eye movements that are compensatory to the direction of actual or perceived tilt of the head relative to gravity. In contrast, no translational horizontal eye movements, which are known to be compensatory to lateral translational motion in primates, were observed under the present experimental conditions.

  18. Touchdown to take-off: at the interface of flight and surface locomotion

    PubMed Central

    2017-01-01

    Small aerial robots are limited to short mission times because aerodynamic and energy conversion efficiency diminish with scale. One way to extend mission times is to perch, as biological flyers do. Beyond perching, small robot flyers benefit from manoeuvring on surfaces for a diverse set of tasks, including exploration, inspection and collection of samples. These opportunities have prompted an interest in bimodal aerial and surface locomotion on both engineered and natural surfaces. To accomplish such novel robot behaviours, recent efforts have included advancing our understanding of the aerodynamics of surface approach and take-off, the contact dynamics of perching and attachment and making surface locomotion more efficient and robust. While current aerial robots show promise, flying animals, including insects, bats and birds, far surpass them in versatility, reliability and robustness. The maximal size of both perching animals and robots is limited by scaling laws for both adhesion and claw-based surface attachment. Biomechanists can use the current variety of specialized robots as inspiration for probing unknown aspects of bimodal animal locomotion. Similarly, the pitch-up landing manoeuvres and surface attachment techniques of animals can offer an evolutionary design guide for developing robots that perch on more diverse and complex surfaces. PMID:28163884

  19. Reusable aerospace system with horizontal take-off

    NASA Astrophysics Data System (ADS)

    Lozino-Lozinskii, G. E.; Shkadov, L. M.; Plokhikh, V. P.

    1990-10-01

    An aerospace system (ASS) concept aiming at cost reductions for launching facilities, reduction of ground preparations for start and launch phases, flexibility of use, international inspection of space systems, and emergency rescue operations is presented. The concept suggests the utilization of an AN-225 subsonic carrier aircraft capable of carrying up to 250 ton of the external load, external fuel tank, and orbital spacecraft. It includes a horizontal take-off, full reusable or single-use system, orbital aircraft with hypersonic characteristics, the use of an air-breathing jet engine on the first stage of launch, and the utilization of advanced structural materials. Among possible applications for ASS are satellite launches into low supporting orbits, suborbital cargo and passenger flights, scientific and economic missions, and the technical servicing of orbital vehicles and stations.

  20. Vertical view of Apollo 16 landing site located Descartes area lunar nearside

    NASA Technical Reports Server (NTRS)

    1971-01-01

    A vertical view of the Apollo 16 landing site located in the Descartes area lunar nearside. The overlay indicates the location of the proposed touchdown point for the Apollo 16 Lunar Module. Descartes is located west of the Sea of Nectar and southwest of the Sea of Tranquility. This photograph was taken with a 500mm lens camera from lunar orbit by the Apollo 14 crew.

  1. Modification of Eye Movements and Motion Perception during Off-Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.; Denise, P.; CLement, G.

    2006-01-01

    Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity. The ensuing ocular reflexes include modulation of both torsional and horizontal eye movements as a function of the varying linear acceleration along the lateral plane, and modulation of vertical and vergence eye movements as a function of the varying linear acceleration along the sagittal plane. Previous studies have demonstrated that tilt and translation otolith-ocular responses, as well as motion perception, vary as a function of stimulus frequency during OVAR. The purpose of this study is to examine normative OVAR responses in healthy human subjects, and examine adaptive changes in astronauts following short duration space flight at low (0.125 Hz) and high (0.5 Hz) frequencies. Data was obtained on 24 normative subjects (14 M, 10 F) and 14 (13 M, 1F) astronaut subjects. To date, astronauts have participated in 3 preflight sessions (n=14) and on R+0/1 (n=7), R+2 (n= 13) and R+4 (n= 13) days after landing. Subjects were rotated in darkness about their longitudinal axis 20 deg off-vertical at constant rates of 45 and 180 deg/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with video-oculography. Perceived motion was evaluated using verbal reports and a two-axis joystick (pitch and roll tilt) mounted on top of a two-axis linear stage (anterior-posterior and medial-lateral translation). Eye responses were obtained in ten of the normative subjects with the head and trunk aligned, and then with the head turned relative to the trunk 40 deg to the right or left of center. Sinusoidal curve fits were used to derive amplitude, phase and bias of the responses over several cycles at each stimulus frequency. Eye responses during 0.125 Hz OVAR were dominated by modulation of torsional and vertical eye position, compensatory for tilt relative to gravity. While there is a bias horizontal slow phase velocity (SPV), the

  2. Land Use Cover Changes and Run Off Potention of Cipunten Agung Watershed Banten

    NASA Astrophysics Data System (ADS)

    Karima, A.; Kaswanto, R. L.

    2017-10-01

    The changes of landscape form such as Land Use Cover Changes (LUCC) of Cipunten Agung watershed could be identified periodically in 1995, 2005, and 2015. In general, land utilization in Cipunten Agung classified into protected region and cultivated region. In 2011, total of protected area is 885.80 ha or 22.54% of watershed area. Those conditions affected both positively to the community development and negatively to the water quantity condition in Cipunten Agung such as flooding, run off, and erosion. Therefore, the purpose of this research is to analyze LUCC impacts to run off potential in Cipunten Agung watershed. Supervised classification method and Soil Conservation Services (Qscs) approach were correlated to determine the figure out an optimal solution to reduce the rate of LUCC. Cipunten Agung watershed imagery was classified into five classes, namely water bodies, forest, cultivated tree, settlement and paddy field. The result shows that area of cultivation tree and paddy fields are larger than others in midstream, and settlement is denser in downstream, particularly at riparian landscapes. The LUCC into paddy field often occur at two period 1995 to 2005 and 2005 to 2015 with several area are 530.92 ha and 388.17 ha. The Qscs method calculation result for 1995 until 2015 was affected by land use cover composition in each year and it was defined by Curve Number (CN). High rainfall in 1995 was generating high run off potential volume. Nevertheless, curve number value was increase get near to 100, which indicate the potential of run off volume increases along with LUCC in each year, those are 70.95; 72.47; and 72.81.

  3. Take-off analysis of the Olympic ski jumping competition (HS-106m).

    PubMed

    Virmavirta, Mikko; Isolehto, Juha; Komi, Paavo; Schwameder, Hermann; Pigozzi, Fabio; Massazza, Giuseppe

    2009-05-29

    The take-off phase (approximately 6m) of the jumps of all athletes participating in the individual HS-106m hill ski jumping competition at the Torino Olympics was filmed with two high-speed cameras. The high altitude of the Pragelato ski jumping venue (1600m) and slight tail wind in the final jumping round were expected to affect the results of this competition. The most significant correlation with the length of the jump was found in the in-run velocity (r=0.628, p<0.001, n=50). This was a surprise in Olympic level ski jumping, and suggests that good jumpers simply had smaller friction between their skis and the in-run tracks and/or the aerodynamic quality of their in-run position was better. Angular velocity of the hip joint of the best jumpers was also correlated with jumping distance (r=0.651, p<0.05, n=10). The best jumpers in this competition exhibited very different take-off techniques, but still they jumped approximately the same distance. This certainly improves the interests in ski jumping among athletes and spectators. The comparison between the take-off techniques of the best jumpers showed that even though the more marked upper body movement creates higher air resistance, it does not necessarily result in shorter jumping distance if the exposure time to high air resistance is not too long. A comparison between the first and second round jumps of the same jumpers showed that the final results in this competition were at least partly affected by the wind conditions.

  4. Viability of Cross-Flow Fan with Helical Blades for Vertical Take-off and Landing Aircraft

    DTIC Science & Technology

    2012-09-01

    fluid dynamics (CFD) software, ANSYS - CFX , a three-dimensional (3-D) straight-bladed model was validated against previous study’s experimental results...computational fluid dynamics software (CFD), ANSYS - CFX , a three-dimensional (3-D) straight-bladed model was validated against previous study’s experimental...37 B. SIZING PARAMETERS AND ILLUSTRATION ................................. 37 APPENDIX B. ANSYS CFX PARAMETERS

  5. Study of Pilot Visual Information Requirements for Navy Vertical Take-Off and Landing Capability Development,

    DTIC Science & Technology

    1979-06-01

    PAGE VI-102 z C - - a. .2 0 a0@ o £o 0 ~ 0 Bp11 zo -cn D0 >4- *~I T? T! 0F MIL I "’I* % I H il U_ IZ 7.. NAEC-MISC-91-0R019 S- - - - AGE VI-103 9: Z~t 0... 81019 . X0v9 ’ 90* .olollf Mf*tat dotte deck C00040’ 2 AmŔe’ 09 Engageco 3 Re LO 1 ttd 6-co 1-c 00 0;t-nC1 n aec" STANDARD L*IGOOIN EO9JPWFNT OVERHEAD

  6. The shock-absorbed system of the airplane landing gear

    NASA Technical Reports Server (NTRS)

    Callerio, Pietro

    1940-01-01

    A discussion is given of the behavior of the shock-absorbing system, consisting of elastic struts and tires, under landing, take-off, and taxying conditions, and a general formula derived for obtaining the minimum stroke required to satisfy the conditions imposed on the landing gear. Finally, the operation of some typical shock-absorbing systems are examined and the necessity brought out for taking into account, in dynamic landing-gear tests, the effect of the wing lift at the instant of contact with the ground.

  7. Performance of arrays of direct-driven wave energy converters under optimal power take-off damping

    NASA Astrophysics Data System (ADS)

    Wang, Liguo; Engström, Jens; Leijon, Mats; Isberg, Jan

    2016-08-01

    It is well known that the total power converted by a wave energy farm is influenced by the hydrodynamic interactions between wave energy converters, especially when they are close to each other. Therefore, to improve the performance of a wave energy farm, the hydrodynamic interaction between converters must be considered, which can be influenced by the power take-off damping of individual converters. In this paper, the performance of arrays of wave energy converters under optimal hydrodynamic interaction and power take-off damping is investigated. This is achieved by coordinating the power take-off damping of individual converters, resulting in optimal hydrodynamic interaction as well as higher production of time-averaged power converted by the farm. Physical constraints on motion amplitudes are considered in the solution, which is required for the practical implementation of wave energy converters. Results indicate that the natural frequency of a wave energy converter under optimal damping will not vary with sea states, but the production performance of a wave energy farm can be improved significantly while satisfying the motion constraints.

  8. Highly efficient organic solar cells with improved vertical donor-acceptor compositional gradient via an inverted off-center spinning method

    DOE PAGES

    Huang, Jiang; Carpenter, Joshua H.; Li, Chang -Zhi; ...

    2015-12-02

    A novel, yet simple solution fabrication technique to address the trade-off between photocurrent and fill factor in thick bulk heterojunction organic solar cells is described. Lastly, the inverted off-center spinning technique promotes a vertical gradient of the donor–acceptor phase-separated morphology, enabling devices with near 100% internal quantum efficiency and a high power conversion efficiency of 10.95%.

  9. Tilt and Translation Motion Perception during Off Vertical Axis Rotation

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Reschke, Millard F.; Clement, Gilles

    2006-01-01

    The effect of stimulus frequency on tilt and translation motion perception was studied during constant velocity off-vertical axis rotation (OVAR), and compared to the effect of stimulus frequency on eye movements. Fourteen healthy subjects were rotated in darkness about their longitudinal axis 10deg and 20deg off-vertical at 0.125 Hz, and 20deg offvertical at 0.5 Hz. Oculomotor responses were recorded using videography, and perceived motion was evaluated using verbal reports and a joystick with four degrees of freedom (pitch and roll tilt, mediallateral and anteriorposterior translation). During the lower frequency OVAR, subjects reported the perception of progressing along the edge of a cone. During higher frequency OVAR, subjects reported the perception of progressing along the edge of an upright cylinder. The modulation of both tilt recorded from the joystick and ocular torsion significantly increased as the tilt angle increased from 10deg to 20deg at 0.125 Hz, and then decreased at 0.5 Hz. Both tilt perception and torsion slightly lagged head orientation at 0.125 Hz. The phase lag of torsion increased at 0.5 Hz, while the phase of tilt perception did not change as a function of frequency. The amplitude of both translation perception recorded from the joystick and horizontal eye movements was negligible at 0.125 Hz and increased as a function of stimulus frequency. While the phase lead of horizontal eye movements decreased at 0.5 Hz, the phase of translation perception did not vary with stimulus frequency and was similar to the phase of tilt perception during all conditions. During dynamic linear acceleration in the absence of other sensory input (canal, vision) a change in stimulus frequency alone elicits similar changes in the amplitude of both self motion perception and eye movements. However, in contrast to the eye movements, the phase of both perceived tilt and translation motion is not altered by stimulus frequency. We conclude that the neural processing

  10. A Horizontal Take-off and Landing satellite launcher or aerospace plane (HOTOL)

    NASA Astrophysics Data System (ADS)

    Conchie, P. J.

    1985-09-01

    An assessment is made of the technology readiness and typical mission profile of a Horizontal Takeoof and Landing (HOTOL) single-stage satellite launch vehicle for 1990s deployment. HOTOL would employ H2-fueled air-breathing propulsion for the first stage of its ascent to low earth orbit through the lower portions of the atmosphere; it would then switch to H2-fueled rocket engines using liquid oxygen from internal tanks for exoatmospheric flight and orbit insertion. Mission cost comparisons are made with alternative launch vehicle design options. HOTOL is approximately the same size as the Concorde SST, and will weigh so much less than the current Space Shuttle as to significantly reduce reentry speeds and temperatures, obviating ceramic insulation systems for the primary structure.

  11. 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.

  12. Vertical land motion controls regional sea level rise patterns on the United States east coast since 1900

    NASA Astrophysics Data System (ADS)

    Piecuch, C. G.; Huybers, P. J.; Hay, C.; Mitrovica, J. X.; Little, C. M.; Ponte, R. M.; Tingley, M.

    2017-12-01

    Understanding observed spatial variations in centennial relative sea level trends on the United States east coast has important scientific and societal applications. Past studies based on models and proxies variously suggest roles for crustal displacement, ocean dynamics, and melting of the Greenland ice sheet. Here we perform joint Bayesian inference on regional relative sea level, vertical land motion, and absolute sea level fields based on tide gauge records and GPS data. Posterior solutions show that regional vertical land motion explains most (80% median estimate) of the spatial variance in the large-scale relative sea level trend field on the east coast over 1900-2016. The posterior estimate for coastal absolute sea level rise is remarkably spatially uniform compared to previous studies, with a spatial average of 1.4-2.3 mm/yr (95% credible interval). Results corroborate glacial isostatic adjustment models and reveal that meaningful long-period, large-scale vertical velocity signals can be extracted from short GPS records.

  13. Vertical motions in Northern Victoria Land inferred from GPS: A comparison with a glacial isostatic adjustment model

    USGS Publications Warehouse

    Mancini, F.; Negusini, M.; Zanutta, A.; Capra, A.

    2007-01-01

    Following the densification of GPS permanent and episodic trackers in Antarctica, geodetic observations are playing an increasing role in geodynamics research and the study of the glacial isostatic adjustment (GIA). The improvement in geodetic measurements accuracy suggests their use in constraining GIA models. It is essential to have a deeper knowledge on the sensitivity of GPS data to motionsrelated to long-term ice mass changes and the present-day mass imbalance of the ice sheets. In order to investigate the geodynamic phenomena in Northern Victoria Land (NVL), GPS geodetic observations were made during the last decade within the VLNDEF (Victoria Land Network for Deformation control) project. The processed data provided a picture of the motions occurring in NVL with a high level of accuracy and depicts, for the whole period, a well defined pattern of vertical motion. The comparison between GPS-derived vertical displacementsand GIA is addressed, showing a good degree of agreement and highlighting the future use of geodetic GPS measurements as constraints in GIA models. In spite of this agreement, the sensitivity of GPS vertical rates to non-GIA vertical motions has to be carefully evaluated.

  14. Contribution of vertical land motions to coastal sea level variations: a global synthesis of multisatellite altimetry, tide gauge and GPS measurements

    NASA Astrophysics Data System (ADS)

    Pfeffer, Julia; Allemand, Pascal

    2016-04-01

    Coastal sea level variations result from a complex mix of climatic, oceanic and geodynamical processes driven by natural and anthropogenic constraints. Combining data from multiple sources is one solution to identify particular processes and progress towards a better understanding of the sea level variations and the assessment of their impacts at coast. Here, we present a global database merging multisatellite altimetry with tide gauges and Global Positioning System (GPS) measurements. Vertical land motions and sea level variations are estimated simultaneously for a network of 886 ground stations with median errors lower than 1 mm/yr. The contribution of vertical land motions to relative sea level variations is explored to better understand the natural hazards associated with sea level rise in coastal areas. Worldwide, vertical land motions dominate 30 % of observed coastal trends. The role of the crust is highly heterogeneous: it can amplify, restrict or counter the effects of climate-induced sea level change. A set of 182 potential vulnerable localities are identified by large coastal subsidence which increases by several times the effects of sea level rise. Though regional behaviours exist, principally caused by GIA (Glacial Isostatic Adjustment), the local variability in vertical land motion prevails. An accurate determination of the vertical motions observed at the coast is fundamental to understand the local processes which contribute to sea level rise, to appraise its impacts on coastal populations and make future predictions.

  15. Concept identification for a power take-off shielding campaign.

    PubMed

    Tinc, P J; Madden, E; Park, S; Weil, R; Sorensen, J A

    2015-01-01

    ABSTRACT Machinery entanglements, specifically power take-off (PTO) entanglements, are a leading cause of injuries and fatalities on farms. In order to address this life-threatening issue, a social marketing campaign is being developed to reduce barriers and emphasize motivators to shielding. This article discusses the process of designing, testing, and selecting concepts to be used in the campaign. Small-group discussions (triads) were held to test 13 message concepts. Participants were asked to provide feedback and select the two messages that they believed to be most powerful. Upon completion, three message concepts were selected to be finalized.

  16. Optimal Trajectories for the Helicopter in One-Engine-Inoperative Terminal-Area Operations

    NASA Technical Reports Server (NTRS)

    Zhao, Yiyuan; Chen, Robert T. N.

    1996-01-01

    This paper presents a summary of a series of recent analytical studies conducted to investigate One-Engine-Inoperative (OEI) optimal control strategies and the associated optimal trajectories for a twin engine helicopter in Category-A terminal-area operations. These studies also examine the associated heliport size requirements and the maximum gross weight capability of the helicopter. Using an eight states, two controls, augmented point-mass model representative of the study helicopter, Continued TakeOff (CTO), Rejected TakeOff (RTO), Balked Landing (BL), and Continued Landing (CL) are investigated for both Vertical-TakeOff-and-Landing (VTOL) and Short-TakeOff-and-Landing (STOL) terminal-area operations. The formulation of the nonlinear optimal control problems with considerations for realistic constraints, solution methods for the two-point boundary-value problem, a new real-time generation method for the optimal OEI trajectories, and the main results of this series of trajectory optimization studies are presented. In particular, a new balanced- weight concept for determining the takeoff decision point for VTOL Category-A operations is proposed, extending the balanced-field length concept used for STOL operations.

  17. Vanguard 2C VTOL Airplane Tested in the Ames 40x80 Foot Wind Tunnel.

    NASA Image and Video Library

    1960-02-01

    Vanguard 2C vertical take-off and landing (VTOL) airplane, wind tunnel test. Front view from below, model 14 1/2 feet high disk off. Nasa Ames engineer Ralph Maki in photo. Variable height struts and ground plane, low pressure ratio, fan in wing. 02/01/1960.

  18. Spatiotemporal assessment and trade-offs of multiple ecosystem services based on land use changes in Zengcheng, China.

    PubMed

    Sun, Xiao; Li, Feng

    2017-12-31

    Driven by rapid urbanization, land use change has become a significant factor influencing ecosystem services (ESs). To support the decision-making process of city planners and policy makers, assessing the spatiotemporal changes associated with multiple ESs is vital. In this study, we developed a general structure to assess the changes of multiple ESs in Zengcheng, China. A new index also was developed to measure the comprehensive ecosystem service (CES). Trade-offs of various ESs were analyzed by using correlation analysis. We then designed four alternate scenarios to explore the optimal land use strategies to increase the CES value and minimize trade-offs among various ESs. Results demonstrated that rapid expansion of built-up land and traffic land resulted in a decrease of CES in Zengcheng from 2003 to 2013. Although the water supply, water purification, and vegetable and fruit production services increased, the climate regulation, soil conservation, biodiversity protection, recreation opportunity and grain production services decreased during the ten-year period. Government should implement land use policies and ecological engineering measures to improve soil conservation in the northern region; recreation opportunity in the central region; and carbon storage, water purification, biodiversity protection and recreation opportunity in the southern region. Among all alternative scenarios, woodland buffer and soil conservation scenarios exhibit the highest CES values, indicating that policies such as the "Ecological corridor construction" project and the "Grain for Green" project should be implemented. However, a caveat is that these policies improve the ESs at the expense of food production due to significant trade-off relationships. To minimize the trade-offs, a more sustainable intensification of agriculture should be adopted to increase food production without decreasing other ESs or occupying additional land. The land use strategies and ecological engineering

  19. Take-off engine particle emission indices for in-service aircraft at Los Angeles International Airport.

    PubMed

    Moore, Richard H; Shook, Michael A; Ziemba, Luke D; DiGangi, Joshua P; Winstead, Edward L; Rauch, Bastian; Jurkat, Tina; Thornhill, Kenneth L; Crosbie, Ewan C; Robinson, Claire; Shingler, Taylor J; Anderson, Bruce E

    2017-12-19

    We present ground-based, advected aircraft engine emissions from flights taking off at Los Angeles International Airport. 275 discrete engine take-off plumes were observed on 18 and 25 May 2014 at a distance of 400 m downwind of the runway. CO 2 measurements are used to convert the aerosol data into plume-average emissions indices that are suitable for modelling aircraft emissions. Total and non-volatile particle number EIs are of order 10 16 -10 17 kg -1 and 10 14 -10 16 kg -1 , respectively. Black-carbon-equivalent particle mass EIs vary between 175-941 mg kg -1 (except for the GE GEnx engines at 46 mg kg -1 ). Aircraft tail numbers recorded for each take-off event are used to incorporate aircraft- and engine-specific parameters into the data set. Data acquisition and processing follow standard methods for quality assurance. A unique aspect of the data set is the mapping of aerosol concentration time series to integrated plume EIs, aircraft and engine specifications, and manufacturer-reported engine emissions certifications. The integrated data enable future studies seeking to understand and model aircraft emissions and their impact on air quality.

  20. Take-off engine particle emission indices for in-service aircraft at Los Angeles International Airport

    PubMed Central

    Moore, Richard H.; Shook, Michael A.; Ziemba, Luke D.; DiGangi, Joshua P.; Winstead, Edward L.; Rauch, Bastian; Jurkat, Tina; Thornhill, Kenneth L.; Crosbie, Ewan C.; Robinson, Claire; Shingler, Taylor J.; Anderson, Bruce E.

    2017-01-01

    We present ground-based, advected aircraft engine emissions from flights taking off at Los Angeles International Airport. 275 discrete engine take-off plumes were observed on 18 and 25 May 2014 at a distance of 400 m downwind of the runway. CO2 measurements are used to convert the aerosol data into plume-average emissions indices that are suitable for modelling aircraft emissions. Total and non-volatile particle number EIs are of order 1016–1017 kg−1 and 1014–1016 kg−1, respectively. Black-carbon-equivalent particle mass EIs vary between 175–941 mg kg−1 (except for the GE GEnx engines at 46 mg kg−1). Aircraft tail numbers recorded for each take-off event are used to incorporate aircraft- and engine-specific parameters into the data set. Data acquisition and processing follow standard methods for quality assurance. A unique aspect of the data set is the mapping of aerosol concentration time series to integrated plume EIs, aircraft and engine specifications, and manufacturer-reported engine emissions certifications. The integrated data enable future studies seeking to understand and model aircraft emissions and their impact on air quality. PMID:29257135

  1. Take-off engine particle emission indices for in-service aircraft at Los Angeles International Airport

    NASA Astrophysics Data System (ADS)

    Moore, Richard H.; Shook, Michael A.; Ziemba, Luke D.; Digangi, Joshua P.; Winstead, Edward L.; Rauch, Bastian; Jurkat, Tina; Thornhill, Kenneth L.; Crosbie, Ewan C.; Robinson, Claire; Shingler, Taylor J.; Anderson, Bruce E.

    2017-12-01

    We present ground-based, advected aircraft engine emissions from flights taking off at Los Angeles International Airport. 275 discrete engine take-off plumes were observed on 18 and 25 May 2014 at a distance of 400 m downwind of the runway. CO2 measurements are used to convert the aerosol data into plume-average emissions indices that are suitable for modelling aircraft emissions. Total and non-volatile particle number EIs are of order 1016-1017 kg-1 and 1014-1016 kg-1, respectively. Black-carbon-equivalent particle mass EIs vary between 175-941 mg kg-1 (except for the GE GEnx engines at 46 mg kg-1). Aircraft tail numbers recorded for each take-off event are used to incorporate aircraft- and engine-specific parameters into the data set. Data acquisition and processing follow standard methods for quality assurance. A unique aspect of the data set is the mapping of aerosol concentration time series to integrated plume EIs, aircraft and engine specifications, and manufacturer-reported engine emissions certifications. The integrated data enable future studies seeking to understand and model aircraft emissions and their impact on air quality.

  2. No Evidence of Trade-Off between Farm Efficiency and Resilience: Dependence of Resource-Use Efficiency on Land-Use Diversity

    PubMed Central

    Kahiluoto, Helena; Kaseva, Janne

    2016-01-01

    Efficiency in the use of resources stream-lined for expected conditions could lead to reduced system diversity and consequently endanger resilience. We tested the hypothesis of a trade-off between farm resource-use efficiency and land-use diversity. We applied stochastic frontier production models to assess the dependence of resource-use-efficiency on land-use diversity as illustrated by the Shannon-Weaver index. Total revenue in relation to use of capital, land and labour on the farms in Southern Finland with a size exceeding 30 ha was studied. The data were extracted from the Finnish Profitability Bookkeeping data. Our results indicate that there is either no trade-off or a negligible trade-off of no economic importance. The small dependence of resource-use efficiency on land-use diversity can be positive as well as negative. We conclude that diversification as a strategy to enhance farm resilience does not necessarily constrain resource-use efficiency. PMID:27662475

  3. Application of Classical Land Surveying Measurement Methods for Determining the Vertical Displacement of Railway Bridges

    NASA Astrophysics Data System (ADS)

    Gawronek, Pelagia; Makuch, Maria

    2017-12-01

    The classical measurements of stability of railway bridge, in the context of determining the vertical displacements of the object, consisted on precise leveling of girders and trigonometric leveling of controlled points (fixed into girders' surface). The construction elements, which were measured in two ways, in real terms belonged to the same vertical planes. Altitude measurements of construction were carried out during periodic structural stability tests and during static load tests of bridge by train. The specificity of displacement measurements, the type of measured object and the rail land surveying measurement conditions were determinants to define methodology of altitude measurement. The article presents compatibility of vertical displacements of steel railway bridge, which were developed in two measurement methods. In conclusion, the authors proposed the optimum concept of determining the vertical displacements of girders by using precise and trigonometric leveling (in terms of accuracy, safety and economy of measurement).

  4. Vertical view Apollo 16 Descartes landing sites as photographed by Apollo 14

    NASA Image and Video Library

    1971-01-12

    S72-00147 (January 1972) --- An almost vertical view of the Apollo 16 Descartes landing area, as photographed from the Apollo 14 spacecraft. Overlays are provided to point out extravehicular activity (EVA) Lunar Roving Vehicle (LRV) traverse routes and the nicknames of features. Hold picture with South Ray Crater in lower left corner. North will then be at the top. The Roman numerals indicate EVA numbers and the Arabic numbers point out stations or traverse stops.

  5. The welfare effects of restricting off-highway vehicle access to public lands

    Treesearch

    Paul M. Jakus; John E. Keith; Lu Liu; Dale Blahna

    2010-01-01

    Off-highway vehicle (OHV) use is a rapidly growing outdoor activity that results in a host of environmental and management problems. Federal agencies have been directed to develop travel management plans to improve recreation experiences, reduce social conflicts, and diminish environmental impacts of OHVs. We examine the effect of land access restrictions on the...

  6. An avulsed radial artery with a high take-off.

    PubMed

    Rojas-Marte, Geurys; Chen, On; Verma, Shivani; Rao, Atul; Shani, Jacob; Ayzenberg, Sergey

    2015-04-01

    A 63-year-old female was diagnosed with severe aortic stenosis, who underwent a diagnostic coronary angiography via transradial approach prior an aortic-valve replacement. After imaging the left coronary system, entrapment of the diagnostic catheter was encountered as a result of spasm of the radial artery. An arteriogram of the arm revealed an anatomical variation in the radial artery (high take-off). Several attempts to remove the entrapped catheter resulted in avulsion of the artery, which was managed successfully with coil embolization. To our knowledge, no such complication has been reported. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

  7. Fugitive particulate air emissions from off-road vehicle maneuvers at military training lands

    USDA-ARS?s Scientific Manuscript database

    Military training lands used for off-road vehicle maneuvers may be subject to severe soil loss and air quality degradation as a result of severe wind erosion. The objective of this study was to measure suspended particulate matter resulting from various different vehicle training scenarios. Soil s...

  8. Lunar Landing Research Vehicle (LLRV) in flight lifting off from ramp

    NASA Technical Reports Server (NTRS)

    1964-01-01

    This 1964 NASA Flight Reserch Center photograph shows the Lunar Landing Research Vehicle (LLRV) number 1 in flight at the south base of Edwards Air Force Base. When Apollo planning was underway in 1960, NASA was looking for a simulator to profile the descent to the moon's surface. Three concepts surfaced: an electronic simulator, a tethered device, and the ambitious Dryden contribution, a free-flying vehicle. All three became serious projects, but eventually the NASA Flight Research Center's (FRC) Landing Research Vehicle (LLRV) became the most significant one. Hubert M. Drake is credited with originating the idea, while Donald Bellman and Gene Matranga were senior engineers on the project, with Bellman, the project manager. Simultaneously, and independently, Bell Aerosystems Company, Buffalo, N.Y., a company with experience in vertical takeoff and landing (VTOL) aircraft, had conceived a similar free-flying simulator and proposed their concept to NASA headquarters. NASA Headquarters put FRC and Bell together to collaborate. The challenge was; to allow a pilot to make a vertical landing on earth in a simulated moon environment, one sixth of the earth's gravity and with totally transparent aerodynamic forces in a 'free flight' vehicle with no tether forces acting on it. Built of tubular aluminum like a giant four-legged bedstead, the vehicle was to simulate a lunar landing profile from around 1500 feet to the moon's surface. To do this, the LLRV had a General Electric CF-700-2V turbofan engine mounted vertically in gimbals, with 4200 pounds of thrust. The engine, using JP-4 fuel, got the vehicle up to the test altitude and was then throttled back to support five-sixths of the vehicle's weight, simulating the reduced gravity of the moon. Two hydrogen-peroxide lift rockets with thrust that could be varied from 100 to 500 pounds handled the LLRV's rate of descent and horizontal translations. Sixteen smaller hydrogen-peroxide rockets, mounted in pairs, gave the pilot

  9. Urban Land: Study of Surface Run-off Composition and Its Dynamics

    NASA Astrophysics Data System (ADS)

    Palagin, E. D.; Gridneva, M. A.; Bykova, P. G.

    2017-11-01

    The qualitative composition of urban land surface run-off is liable to significant variations. To study surface run-off dynamics, to examine its behaviour and to discover reasons of these variations, it is relevant to use the mathematical apparatus technique of time series analysis. A seasonal decomposition procedure was applied to a temporary series of monthly dynamics with the annual frequency of seasonal variations in connection with a multiplicative model. The results of the quantitative chemical analysis of surface wastewater of the 22nd Partsjezd outlet in Samara for the period of 2004-2016 were used as basic data. As a result of the analysis, a seasonal pattern of variations in the composition of surface run-off in Samara was identified. Seasonal indices upon 15 waste-water quality indicators were defined. BOD (full), suspended materials, mineralization, chlorides, sulphates, ammonium-ion, nitrite-anion, nitrate-anion, phosphates (phosphorus), iron general, copper, zinc, aluminium, petroleum products, synthetic surfactants (anion-active). Based on the seasonal decomposition of the time series data, the contribution of trends, seasonal and accidental components of the variability of the surface run-off indicators was estimated.

  10. Know Before You Go! Utah's Off-Highway Vehicle Education Student Workbook.

    ERIC Educational Resources Information Center

    Utah State Dept. of Natural Resources, Salt Lake City. Div. of Parks and Recreation.

    This document is intended to teach the riders of off-highway vehicles (OHVs) how to ride safely and legally on Utah's public lands and how to take care of the places in which they ride. OHVs are all-terrain vehicles (ATVs), off-highway motorcycles, and snowmobiles. Receiving a passing grade on the final test and in an associated course on driving…

  11. Different Modes of Feedback and Peak Vertical Ground Reaction Force During Jump Landing: A Systematic Review

    PubMed Central

    Ericksen, Hayley M.; Gribble, Phillip A.; Pfile, Kate R.; Pietrosimone, Brian G.

    2013-01-01

    Context: Excessive ground reaction force when landing from a jump may result in lower extremity injuries. It is important to better understand how feedback can influence ground reaction force (GRF) and potentially reduce injury risk. Objective: To determine the effect of expert-provided (EP), self-analysis (SA), and combination EP and SA (combo) feedback on reducing peak vertical GRF during a jump-landing task. Data Sources: We searched the Web of Science database on July 1, 2011; using the search terms ground reaction force, landing biomechanics, and feedback elicited 731 initial hits. Study Selection: Of the 731 initial hits, our final analysis included 7 studies that incorporated 32 separate data comparisons. Data Extraction: Standardized effect sizes and 95% confidence intervals (CIs) were calculated between pretest and posttest scores for each feedback condition. Data Synthesis: We found a homogeneous beneficial effect for combo feedback, indicating a reduction in GRF with no CIs crossing zero. We also found a homogeneous beneficial effect for EP feedback, but the CIs from 4 of the 10 data comparisons crossed zero. The SA feedback showed strong, definitive effects when the intervention included a videotape SA, with no CIs crossing zero. Conclusions: Of the 7 studies reviewed, combo feedback seemed to produce the greatest decrease in peak vertical GRF during a jump-landing task. PMID:24067153

  12. Human otolith-ocular reflexes during off-vertical axis rotation: effect of frequency on tilt-translation ambiguity and motion sickness

    NASA Technical Reports Server (NTRS)

    Wood, Scott J.; Paloski, W. H. (Principal Investigator)

    2002-01-01

    The purpose of this study was to examine how the modulation of tilt and translation otolith-ocular responses during constant velocity off-vertical axis rotation varies as a function of stimulus frequency. Eighteen human subjects were rotated in darkness about their longitudinal axis 30 degrees off-vertical at stimulus frequencies between 0.05 and 0.8 Hz. The modulation of torsion decreased while the modulation of horizontal slow phase velocity (SPV) increased with increasing frequency. It is inferred that the ambiguity of otolith afferent information is greatest in the frequency region where tilt (torsion) and translational (horizontal SPV) otolith-ocular responses crossover. It is postulated that the previously demonstrated peak in motion sickness susceptibility during linear accelerations around 0.3 Hz is the result of frequency segregation of ambiguous otolith information being inadequate to distinguish between tilt and translation.

  13. The Association of Dorsiflexion Flexibility on Landing Mechanics during a Drop Vertical Jump

    PubMed Central

    Malloy, Philip; Meinerz, Carolyn; Geiser, Christopher; Kipp, Kristof

    2016-01-01

    Purpose While previous studies have examined the association between ankle dorsiflexion flexibility and deleterious landing postures, it is not currently known how landing kinetics are influenced by ankle dorsiflexion flexibility. The purpose of this study was to examine if ankle dorsiflexion flexibility was associated with landing kinematics and kinetics that have been shown to increase the risk of ACL injury in female athletes. Methods Twenty-three female collegiate soccer players participated in a preseason screening that included the assessment of ankle dorsiflexion flexibility and lower-body kinematics and kinetics during a drop vertical jump task. Results The results demonstrated that females with less ankle dorsiflexion flexibility exhibited greater peak knee abduction moments (r = −.442), greater peak knee abduction angles (r = .355), and less peak knee flexion angles (r = −.385) during landing. The range of dorsiflexion flexibility for the current study was between 9°–23° degrees (mean = 15.0°; SD 3.9°). Conclusion Dorsiflexion flexibility may serve as a useful clinical measure to predict poor landing postures and external forces that have been associated with increased knee injury risk. Rehabilitation specialists can provide interventions aimed at improving dorsiflexion flexibility in order to ameliorate the impact of this modifiable factor on deleterious landing kinematics and kinetics in female athletes. PMID:25112598

  14. Use of coastal altimeter and tide gauge data for a seamless land-sea vertical datum in Taiwan

    NASA Astrophysics Data System (ADS)

    Yen-Ti, C.; Hwang, C.

    2017-12-01

    Conventional topographic and hydrographic mappings use two separate reference surfaces, called orthometric datum (TWVD2001 in Taiwan) and chart datum. In Taiwan, land elevations are heights tied to a leveling control network with its zero height at the mean sea surface of Keelung Harbor (realized by the height of Benchmark K999). Ocean depths are counted from the lowest tidal surface defined by tidal measurements near the sites of depth measurements. This paper usesa new method to construct a unified vertical datum for land elevations and ocean depths around Taiwan. First, we determine an optimal mean sea surface model (MSSHM) using refined offshore altimeter data. Then, the ellipsoidal heights of the mean sea levels at 36 tide gauges around Taiwan are determined using GPS measurements at their nearby benchmarks, and are then combined with the altimeter-derived MSSHM to generate a final MSSHM that has a smooth transition from land to sea. We also construct an improved ocean tide model to obtain various tidal surfaces. Using the latest land, shipborne, airborne and altimeter-derived gravity data, we construct a hybrid geoid model to define a vertical datum on land. The final MSSHM is the zero surface that defines ocean tidal heights and lowest tidal values in a ellipsoidal system that is fully consistent with the geodetic system of GNSS. The use of the MSSHM and the hybrid geoid model enables a seamless connection to combine or compare coastal land and sea elevations from a wide range of sources.

  15. Effects of Surface Inclination on the Vertical Loading Rates and Landing Pattern during the First Attempt of Barefoot Running in Habitual Shod Runners.

    PubMed

    An, W; Rainbow, M J; Cheung, R T H

    2015-01-01

    Barefoot running has been proposed to reduce vertical loading rates, which is a risk factor of running injuries. Most of the previous studies evaluated runners on level surfaces. This study examined the effect of surface inclination on vertical loading rates and landing pattern during the first attempt of barefoot running among habitual shod runners. Twenty habitual shod runners were asked to run on treadmill at 8.0 km/h at three inclination angles (0°; +10°; -10°) with and without their usual running shoes. Vertical average rate (VALR) and instantaneous loading rate (VILR) were obtained by established methods. Landing pattern was decided using high-speed camera. VALR and VILR in shod condition were significantly higher (p < 0.001) in declined than in level or inclined treadmill running, but not in barefoot condition (p > 0.382). There was no difference (p > 0.413) in the landing pattern among all surface inclinations. Only one runner demonstrated complete transition to non-heel strike landing in all slope conditions. Reducing heel strike ratio in barefoot running did not ensure a decrease in loading rates (p > 0.15). Conversely, non-heel strike landing, regardless of footwear condition, would result in a softer landing (p < 0.011).

  16. Effects of Surface Inclination on the Vertical Loading Rates and Landing Pattern during the First Attempt of Barefoot Running in Habitual Shod Runners

    PubMed Central

    An, W.; Rainbow, M. J.; Cheung, R. T. H.

    2015-01-01

    Barefoot running has been proposed to reduce vertical loading rates, which is a risk factor of running injuries. Most of the previous studies evaluated runners on level surfaces. This study examined the effect of surface inclination on vertical loading rates and landing pattern during the first attempt of barefoot running among habitual shod runners. Twenty habitual shod runners were asked to run on treadmill at 8.0 km/h at three inclination angles (0°; +10°; −10°) with and without their usual running shoes. Vertical average rate (VALR) and instantaneous loading rate (VILR) were obtained by established methods. Landing pattern was decided using high-speed camera. VALR and VILR in shod condition were significantly higher (p < 0.001) in declined than in level or inclined treadmill running, but not in barefoot condition (p > 0.382). There was no difference (p > 0.413) in the landing pattern among all surface inclinations. Only one runner demonstrated complete transition to non-heel strike landing in all slope conditions. Reducing heel strike ratio in barefoot running did not ensure a decrease in loading rates (p > 0.15). Conversely, non-heel strike landing, regardless of footwear condition, would result in a softer landing (p < 0.011). PMID:26258133

  17. National Study of State Universities and Land Grant Colleges: Off Campus Inservice Activities.

    ERIC Educational Resources Information Center

    Seldin, Clement A.

    Information concerning off-campus inservice activity (OCIA) at state universities and land grant colleges in the United States was surveyed. There was a 92.5 percent response rate to questionnaires sent to 107 deans of schools, colleges, and departments of education. Inservice activities were considered to be courses, workshops, needs assessments,…

  18. Family Practitioners' Advice about Taking Time Off Work for Lower Respiratory Tract Infections: A Prospective Study in Twelve European Primary Care Networks.

    PubMed

    Godycki-Cwirko, Maciek; Nocun, Marek; Butler, Christopher C; Little, Paul; Verheij, Theo; Hood, Kerenza; Fleten, Nils; Kowalczyk, Anna; Melbye, Hasse

    2016-01-01

    Acute cough and lower respiratory tract infections (LRTIs) are one of the most important causes of lost working hours. to explore variation and predictors in family practitioners (FPs) advice to patients with LRTIs about taking time off work in different European countries. Prospective observational study in primary care networks in 12 countries, with multilevel mixed-effects binomial logistic regression. 324 FPs recruited 1616 employed adults who presented to primary care with LRTIs. The proportion of patients advised to take time off work varied from 7.6% in the Netherlands to 89.2% in Slovakia, and of these, 88.2% overall were advised to stay off work for seven days or less. None of Finnish or Dutch patients were advised to take more than 7 days off, in contrast to 35.5% of Polish and 27.0% of Slovak patients. The strongest predictors of FPs' advice about time off work were: patient symptoms interfering with normal activities (OR 4.43; P<0.001), fever (2.49; P<0.001), patients feeling generally unwell (2.21; P<0.001), antibiotic prescribing (1.51; P = 0.025) and auscultation abnormality (1.50; P = 0.029). Advice to take time off was not associated with patient reported recovery. There is large variation in FPs' advice given to patients with LRTIs in Europe about taking time off work, which is not explained by differences in patients' reported illness duration, but might be explained by differences in regulations around certification and sick pay. Evidence based guidance for advising patients about taking time off work for this common condition is needed.

  19. 14 CFR 121.195 - Airplanes: Turbine engine powered: Landing limitations: Destination airports.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Airplanes: Turbine engine powered: Landing... Performance Operating Limitations § 121.195 Airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered airplane may take off that airplane at...

  20. 14 CFR 121.195 - Airplanes: Turbine engine powered: Landing limitations: Destination airports.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Airplanes: Turbine engine powered: Landing... Performance Operating Limitations § 121.195 Airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered airplane may take off that airplane at...

  1. A Take-Home Physics Experiment Kit for On-Campus and Off-Campus Students

    ERIC Educational Resources Information Center

    Turner, Joanna; Parisi, Alfio

    2008-01-01

    A take-home experiment kit has been developed to reinforce the concepts in a first year physics course that both on and off campus students from a variety of educational backgrounds can successfully use. The kit is inexpensive and is composed of easy to obtain items. The experiments conducted with the kit are directed experiments that require…

  2. Volitional Spine Stabilization During a Drop Vertical Jump From Different Landing Heights: Implications for Anterior Cruciate Ligament Injury.

    PubMed

    Haddas, Ram; Hooper, Troy; James, C Roger; Sizer, Phillip S

    2016-12-01

    Volitional preemptive abdominal contraction (VPAC) during dynamic activities may alter trunk motion, but the role of the core musculature in positioning the trunk during landing tasks is unclear. To determine whether volitional core-muscle activation incorporated during a drop vertical jump alters lower extremity kinematics and kinetics, as well as trunk and lower extremity muscle activity at different landing heights. Controlled laboratory study. Clinical biomechanics laboratory. Thirty-two young healthy adults, consisting of 17 men (age = 25.24 ± 2.88 years, height = 1.85 ± 0.06 m, mass = 89.68 ± 16.80 kg) and 15 women (age = 23.93 ± 1.33 years, height = 1.67 ± 0.08 m, mass = 89.68 ± 5.28 kg). Core-muscle activation using VPAC. We collected 3-dimensional ankle, knee, and hip motions, moments, and powers; ground reaction forces; and trunk and lower extremity muscle activity during 0.30- and 0.50-m drop vertical-jump landings. During landing from a 0.30-m height, VPAC performance increased external oblique and semitendinosis activity, knee flexion, and knee internal rotation and decreased knee-abduction moment and knee-energy absorption. During the 0.50-m landing, the VPAC increased external oblique and semitendinosis activity, knee flexion, and hip flexion and decreased ankle inversion and hip-energy absorption. The VPAC performance during landing may protect the anterior cruciate ligament during different landing phases from different heights, creating a protective advantage just before ground contact and after the impact phase. Incorporating VPAC during high injury-risk activities may enhance pelvic stability, improve lower extremity positioning and sensorimotor control, and reduce anterior cruciate ligament injury risk while protecting the lumbar spine.

  3. Tilt Nacelle Vertical and Short Takeoff and Landing Engine

    NASA Image and Video Library

    1979-03-21

    Center Director John McCarthy, left, and researcher Al Johns pose with a one-third scale model of a Grumman Aerospace tilt engine nacelle for Vertical and Short Takeoff and Landing (V/STOL) in the 9- by 15-Foot Low Speed Wind Tunnel at the National Aeronautics and Space Administration (NASA) Lewis Research Center. Lewis researchers had been studying tilt nacelle and inlet issues for several years. One area of concern was the inlet flow separation during the transition from horizontal to vertical flight. The separation of air flow from the inlet’s internal components could significantly stress the fan blades or cause a loss of thrust. In 1978 NASA researchers Robert Williams and Al Johns teamed with Grumman’s H.C. Potonides to develop a series of tests in the Lewis 9- by 15-foot tunnel to study a device designed to delay the flow separation by blowing additional air into the inlet. A jet of air, supplied through the hose on the right, was blown over the inlet surfaces. The researchers verified that the air jet slowed the flow separation. They found that the blowing on boundary layer control resulted in a doubling of the angle-of-attack and decreases in compressor blade stresses and fan distortion. The tests were the first time the concept of blowing air for boundary layer control was demonstrated. Boundary layer control devices like this could result in smaller and lighter V/STOL inlets.

  4. Concurrent Validity of a Portable Force Plate Using Vertical Jump Force-Time Characteristics.

    PubMed

    Lake, Jason; Mundy, Peter; Comfort, Paul; McMahon, John J; Suchomel, Timothy J; Carden, Patrick

    2018-05-29

    This study examined concurrent validity of countermovement vertical jump (CMJ) reactive strength index modified and force-time characteristics recorded using a one dimensional portable and laboratory force plate system. Twenty-eight men performed bilateral CMJs on two portable force plates placed on top of two in-ground force plates, both recording vertical ground reaction force at 1000 Hz. Time to take-off, jump height, reactive strength index modified, braking and propulsion impulse, mean net force, and duration were calculated from the vertical force from both force plate systems. Results from both systems were highly correlated (r≥.99). There were small (d<.12) but significant differences between their respective braking impulse, braking mean net force, propulsion impulse, and propulsion mean net force (p<.001). However, limits of agreement yielded a mean value of 1.7% relative to the laboratory force plate system (95% CL: .9% to 2.5%), indicating very good agreement across all of the dependent variables. The largest limits of agreement belonged to jump height (2.1%), time to take-off (3.4%), and reactive strength index modified (3.8%). The portable force plate system provides a valid method of obtaining reactive strength measures, and several underpinning force-time variables, from unloaded CMJ and practitioners can use both force plates interchangeably.

  5. Using land to mitigate climate change: hitting the target, recognizing the trade-offs.

    PubMed

    Reilly, John; Melillo, Jerry; Cai, Yongxia; Kicklighter, David; Gurgel, Angelo; Paltsev, Sergey; Cronin, Timothy; Sokolov, Andrei; Schlosser, Adam

    2012-06-05

    Land can be used in several ways to mitigate climate change, but especially under changing environmental conditions there may be implications for food prices. Using an integrated global system model, we explore the roles that these land-use options can play in a global mitigation strategy to stabilize Earth's average temperature within 2 °C of the preindustrial level and their impacts on agriculture. We show that an ambitious global Energy-Only climate policy that includes biofuels would likely not achieve the 2 °C target. A thought-experiment where the world ideally prices land carbon fluxes combined with biofuels (Energy+Land policy) gets the world much closer. Land could become a large net carbon sink of about 178 Pg C over the 21st century with price incentives in the Energy+Land scenario. With land carbon pricing but without biofuels (a No-Biofuel scenario) the carbon sink is nearly identical to the case with biofuels, but emissions from energy are somewhat higher, thereby results in more warming. Absent such incentives, land is either a much smaller net carbon sink (+37 Pg C - Energy-Only policy) or a net source (-21 Pg C - No-Policy). The significant trade-off with this integrated land-use approach is that prices for agricultural products rise substantially because of mitigation costs borne by the sector and higher land prices. Share of income spent on food for wealthier regions continues to fall, but for the poorest regions, higher food prices lead to a rising share of income spent on food.

  6. Vertical Takeoff and Landing Vehicle with Increased Cruise Efficiency

    NASA Technical Reports Server (NTRS)

    Langford, William M. (Inventor); Hodges, William T. (Inventor); Laws, Christopher T. (Inventor); Johns, Zachary R. (Inventor); Fredericks, William J. (Inventor); Moore, Mark D. (Inventor); Busan, Ronald C. (Inventor); Rothhaar, Paul M. (Inventor); North, David D. (Inventor); Webb, Sandy R. (Inventor)

    2018-01-01

    Systems, methods, and devices are provided that combine an advance vehicle configuration, such as an advanced aircraft configuration, with the infusion of electric propulsion, thereby enabling a four times increase in range and endurance while maintaining a full vertical takeoff and landing ("VTOL") and hover capability for the vehicle. Embodiments may provide vehicles with both VTOL and cruise efficient capabilities without the use of ground infrastructure. An embodiment vehicle may comprise a wing configured to tilt through a range of motion, a first series of electric motors coupled to the wing and each configured to drive an associated wing propeller, a tail configured to tilt through the range of motion, a second series of electric motors coupled to the tail and each configured to drive an associated tail propeller, and an electric propulsion system connected to the first series of electric motors and the second series of electric motors.

  7. Altus I aircraft taking off from lakebed runway

    NASA Technical Reports Server (NTRS)

    1997-01-01

    The remotely-piloted Altus I aircraft takes off from Rogers Dry Lake adjacent to NASA's Dryden Flight Research Center, Edwards, Calif. The short series of test flights sponsored by the Naval Postgraduate School in early August, 1997, were designed to demonstrate the ability of the experimental craft to cruise at altitudes above 40,000 feet for sustained durations. On its final flight Aug. 15, the Altus I reached an altitude of 43,500 feet. The Altus I and its sister ship, the Altus II, are variants of the Predator surveillance drone built by General Atomics/Aeronautical Systems, Inc. They are designed for high-altitude, long-duration scientific sampling missions, and are powered by turbocharged piston engines. The Altus I incorporates a single-stage turbocharger, while the Altus II, built for NASA's Environmental Research Aircraft and Sensor Technology program, sports a two-stage turbocharger to enable the craft to fly at altitudes above 55,000 feet.

  8. Gender, Vertical Height and Horizontal Distance Effects on Single-Leg Landing Kinematics: Implications for Risk of non-contact ACL Injury.

    PubMed

    Ali, Nicholas; Rouhi, Gholamreza; Robertson, Gordon

    2013-01-01

    There is a lack of studies investigating gender differences in whole-body kinematics during single-leg landings from increasing vertical heights and horizontal distances. This study determined the main effects and interactions of gender, vertical height, and horizontal distance on whole-body joint kinematics during single-leg landings, and established whether these findings could explain the gender disparity in non-contact anterior cruciate ligament (ACL) injury rate. Recreationally active males (n=6) and females (n=6) performed single-leg landings from a takeoff deck of vertical height of 20, 40, and 60 cm placed at a horizontal distance of 30, 50 and 70 cm from the edge of a force platform, while 3D kinematics and kinetics were simultaneously measured. It was determined that peak vertical ground reaction force (VGRF) and the ankle flexion angle exhibited significant gender differences (p=0.028, partial η(2)=0.40 and p=0.035, partial η(2)=0.37, respectively). Peak VGRF was significantly correlated to the ankle flexion angle (r= -0.59, p=0.04), hip flexion angle (r= -0.74, p=0.006), and trunk flexion angle (r= -0.59, p=0.045). Peak posterior ground reaction force (PGRF) was significantly correlated to the ankle flexion angle (r= -0.56, p=0.035), while peak knee abduction moment was significantly correlated to the knee flexion angle (r= -0.64, p=0.03). Rearfoot landings may explain the higher ACL injury rate among females. Higher plantar-flexed ankle, hip, and trunk flexion angles were associated with lower peak ground reaction forces, while higher knee flexion angle was associated with lower peak knee abduction moment, and these kinematics implicate reduced risk of non-contact ACL injury.

  9. Trade-off between land vehicle antenna cost and gain for satellite mobile communications

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Trade-offs between antenna cost and gain made for nine antennas as a feasibility study for the experimental land mobile satellite system, M-SAT(X) reported. This system is under development by JPL-NASA for a mobile telephone system to be used throughout the continental USA and Alaska. The mobile antenna is a key element in the development of this system.

  10. VIDEO REVIEW: Maths in a Box video: Take-off - moving bodies with constant mass

    NASA Astrophysics Data System (ADS)

    Marks, Ken

    1999-09-01

    I write this review as a PGCE maths tutor, and therefore from the perspective of using parts of this series at A-level. The sample video, `Take-off - moving bodies with constant mass', is a good example of combining real footage with commentary as the viewer is invited to think about modelling the take-off of an aircraft. The style is reminiscent of Open University presentations and here the challenge is to determine the necessary length of the runway. The video is split into two sections. The first, commentary, section works quite well, although it jars a bit to hear Newton's Third Law put across as `Action and reaction are equal and opposite'; this is a familiar offering but one that still causes mystification in the sixth form. The viewer is invited to think about setting up equations, and reminded that the chain rule will be necessary to solve the differential equation generated from Newton's Second Law. This gives a good indication of the level of mathematics required. Unfortunately the flow is then somewhat disturbed by a strong emphasis on boundary conditions. If the student can cope with the general level of calculus required, this aspect of the challenge would also seem to fit more naturally into the second section of the video. This second section looks at setting up the equations and `solutions'. It can be used after classroom discussion, and takes the viewer through three, increasingly sophisticated, models involving functions for drag and resistance forces. On the whole this is clear and helpful, but for some reason the solutions each stop with an equation linking the length of the runway to the take-off velocity, failing to make use of the second equation to eliminate this intermediate variable. All in all, it is a useful addition to resources for A-level, particularly if students are also following the sort of mechanics syllabus (within mathematics) that emphasizes modelling.

  11. Applicability of the control configured design approach to advanced earth orbital transportation systems

    NASA Technical Reports Server (NTRS)

    Hepler, A. K.; Zeck, H.; Walker, W. H.; Shafer, D. E.

    1978-01-01

    The applicability of the control configured design approach (CCV) to advanced earth orbital transportation systems was studied. The baseline system investigated was fully reusable vertical take-off/horizontal landing single-stage-to-orbit vehicle and had mission requirements similar to the space shuttle orbiter. Technical analyses were made to determine aerodynamic, flight control and subsystem design characteristics. Figures of merit were assessed on vehicle dry weight and orbital payload. The results indicated that the major parameters for CCV designs are hypersonic trim, aft center of gravity, and control surface heating. Optimized CCV designs can be controllable and provide substantial payload gains over conventional non-CCV design vertical take-off vehicles.

  12. Improvements to the FATOLA computer program including added actively controlled landing gear subroutines

    NASA Technical Reports Server (NTRS)

    Mall, G. H.

    1983-01-01

    Modifications to a multi-degree-of-freedom flexible aircraft take-off and landing analysis (FATOLA) computer program, including a provision for actively controlled landing gears to expand the programs simulation capabilities, are presented. Supplemental instructions for preparation of data and for use of the modified program are included.

  13. Assessment of vertical soil solid phase transport (pedoturbations) in different types of land use by magnetic tracer method (Belgorod region, Russia)

    NASA Astrophysics Data System (ADS)

    Zhidkin, Andrey

    2015-04-01

    New method of quantitative assessments of vertical soil solid phase transport (pedoturbations) is based on redistribution of spherical magnetic particles (SMP) in soil profiles. SMP - are fly ash components, which mainly produce during coal burning. The main sources of SMP on studied object were locomotives on the railroads, which used coal at the turn of the XIX century. SMP income into the soil only from the atmosphere, very stable for destructions, can be preserved in soils for centuries, and have the same size and weight as the soil matter. So SMP redistribution reflects soil solid phase transport. SMP used as tracers of soil erosion (Olson et.al., 2013), but for the first time applied for quantitative assessments of pedoturbations. In Belgorod region of Russia studied vertical distribution of SMP in soils in different types of land use: a) arable chernozem about 160-year plowing, b) arable chernozem 120-year plowing, c) dark-gray forest soil, which didn't plow at least last 150 years. All three sites are located nearby for the same physical-geography conditions. Distribution of SMP studied layer by layer (thickness of the layer 7 cm) from the top to 70 cm depth, in triplicate soil columns in every land use type (totally 90 soil samples). The period of SMP kept in studied soils is about 115 years. Revealed the different depth of SMP penetration (burial) in soil profiles for this period: 49 cm in the soil of 160-year arable land, 58 cm in the soil of 120-year arable land and 68 cm in the virgin forest soil. Different depth of SMP penetration is connected with different activity of pedoturbations, which differs according to the composition of soil flora and fauna, root activity, and animal mixing work. It is supposed that in the arable land single cropping can reduce the thickness of the active layer and as a result the zone of active pedoturbation depth. Based on SMP distribution counted rates of vertical soil solid phase transport, which are equaled: 31 t

  14. Collins Aerodyne VTOL aircraft investigations

    NASA Image and Video Library

    1960-01-11

    Collins Aerodyne vertical take-off and landing (VTOL) aircraft investigations. Ground plane support system. 3/4 front view. Dave Koening (from Collins Aerodyne) in photo. Mounted on variable height struts, ground board system, zero degree angle of attack. 01/11/1960

  15. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take off... this section, no person operating a turbine engine powered large transport category airplane may take...

  16. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take off... this section, no person operating a turbine engine powered large transport category airplane may take...

  17. Rocket-based combined-cycle (RBCC) powered spaceliner class vehicle can advantageously employ vertical takeoff and landing (VTOL)

    NASA Technical Reports Server (NTRS)

    Escher, William J. D.

    1995-01-01

    The subject is next generation orbital space transporation, taken to be fully reusable non-staged 'aircraft like' systems targeted for routine, affordable access to space. Specifically, the takeoff and landing approach to be selected for such systems is considered, mainly from a propulsion viewpoint. Conventional wisdom has it that any transatmospheric-class vehicle which uses high-speed airbreathing propulsion modes (e.g., scramjet) intrinsically must utilize horizontal takeoff and landing, HTOHL. Although this may be true for all-airbreathing propulsion (i.e., no rocket content as in turboramjet propulsion), that emerging class of powerplant which integrally combines airbreathing and rocket propulsion, referred to as rocket-based combined-cycle (RBCC) propulsion, is considerably more flexible with respect to selecting takeoff/landing modes. In fact, it is proposed that any of the modes of interest may potentially be selected: HTOHL, VTOHL, VTOVL. To illustrate this surmise, the case of a previously documented RBCC-powered 'Spaceliner' class space transport concept, which is designed for vertical takeoff and landing, is examined. The 'RBCC' and 'Spaceliner' categories are first described for background. Departing form an often presumed HTOHL baseline, the leading design and operational advantages of moving to VTOVL are then elucidated. Technical substantiation that the RBCC approach, in fact, enables this capability (but also that of HTOHL and VTOVL) is provided, with extensive reference to case-in-point supporting studies. The paper closes with a set of conditional surmises bearing on its set of conclusions, which point up the operational cost advantages associated with selecting the vertical takeoff and landing mode combination (VTOL), uniquely offered by RBCC propulsion.

  18. Rocket-based combined-cycle (RBCC) powered spaceliner class vehicle can advantageously employ vertical takeoff and landing (VTOL)

    NASA Astrophysics Data System (ADS)

    Escher, William J. D.

    The subject is next generation orbital space transporation, taken to be fully reusable non-staged 'aircraft like' systems targeted for routine, affordable access to space. Specifically, the takeoff and landing approach to be selected for such systems is considered, mainly from a propulsion viewpoint. Conventional wisdom has it that any transatmospheric-class vehicle which uses high-speed airbreathing propulsion modes (e.g., scramjet) intrinsically must utilize horizontal takeoff and landing, HTOHL. Although this may be true for all-airbreathing propulsion (i.e., no rocket content as in turboramjet propulsion), that emerging class of powerplant which integrally combines airbreathing and rocket propulsion, referred to as rocket-based combined-cycle (RBCC) propulsion, is considerably more flexible with respect to selecting takeoff/landing modes. In fact, it is proposed that any of the modes of interest may potentially be selected: HTOHL, VTOHL, VTOVL. To illustrate this surmise, the case of a previously documented RBCC-powered 'Spaceliner' class space transport concept, which is designed for vertical takeoff and landing, is examined. The 'RBCC' and 'Spaceliner' categories are first described for background. Departing form an often presumed HTOHL baseline, the leading design and operational advantages of moving to VTOVL are then elucidated. Technical substantiation that the RBCC approach, in fact, enables this capability (but also that of HTOHL and VTOVL) is provided, with extensive reference to case-in-point supporting studies. The paper closes with a set of conditional surmises bearing on its set of conclusions, which point up the operational cost advantages associated with selecting the vertical takeoff and landing mode combination (VTOL), uniquely offered by RBCC propulsion.

  19. Land use efficiency: anticipating future demand for land-sector greenhouse gas emissions abatement and managing trade-offs with agriculture, water, and biodiversity.

    PubMed

    Bryan, Brett A; Crossman, Neville D; Nolan, Martin; Li, Jing; Navarro, Javier; Connor, Jeffery D

    2015-11-01

    Competition for land is increasing, and policy needs to ensure the efficient supply of multiple ecosystem services from land systems. We modelled the spatially explicit potential future supply of ecosystem services in Australia's intensive agricultural land in response to carbon markets under four global outlooks from 2013 to 2050. We assessed the productive efficiency of greenhouse gas emissions abatement, agricultural production, water resources, and biodiversity services and compared these to production possibility frontiers (PPFs). While interacting commodity markets and carbon markets produced efficient outcomes for agricultural production and emissions abatement, more efficient outcomes were possible for water resources and biodiversity services due to weak price signals. However, when only two objectives were considered as per typical efficiency assessments, efficiency improvements involved significant unintended trade-offs for the other objectives and incurred substantial opportunity costs. Considering multiple objectives simultaneously enabled the identification of land use arrangements that were efficient over multiple ecosystem services. Efficient land use arrangements could be selected that meet society's preferences for ecosystem service provision from land by adjusting the metric used to combine multiple services. To effectively manage competition for land via land use efficiency, market incentives are needed that effectively price multiple ecosystem services. © 2015 John Wiley & Sons Ltd.

  20. Simulation of jet blast effect on landing aircraft

    DOT National Transportation Integrated Search

    2001-01-01

    Presents a model to measure the effects of various kinds and sizes of jet blast from an airplane that is taking off on a path at right angle to and traveling away from a jet that is landing. With increasingly powerful engines and growing capacity and...

  1. Design of a Low Cost Short Takeoff-vertical Landing Export Fighter/attack Aircraft

    NASA Technical Reports Server (NTRS)

    Belcher, Anne; Bodeker, Dan, III; Miu, Steve; Petro, Laura; Senf, Cary Taylor; Woeltjen, Donald

    1990-01-01

    The design of a supersonic short takeoff and vertical landing (STOVL) aircraft is presented that is suitable for export. An advanced four poster, low bypass turbofan engine is to be used for propulsion. Preliminary aerodynamic analysis is presented covering a determination of CD versus CL, CD versus Mach number, as well as best cruise Mach number and altitude. Component locations are presented and center of gravity determined. Cost minimization is achieved through the use of developed subsystems and standard fabrication techniques using nonexotic materials. Conclusions regarding the viability of the STOVL design are presented.

  2. Soil stabilization mat for lunar launch/landing site

    NASA Technical Reports Server (NTRS)

    Acord, Amy L.; Cohenour, Mark W.; Ephraim, Daniel; Gochoel, Dennis; Roberts, Jefferson G.

    1990-01-01

    Facilities which are capable of handling frequent arrivals and departures of spaceships between Earth and a lunar colony are necessary. The facility must be able to provide these services with minimal interruption of operational activity within the colony. The major concerns associated with the space traffic are the dust and rock particles that will be kicked up by the rocket exhaust. As a result of the reduced gravitation of the Moon, these particles scatter over large horizontal distances. This flying debris will not only seriously interrupt the routine operations of the colony, but could cause damage to the equipment and facilities surrounding the launch site. An approach to overcome this problem is presented. A proposed design for a lunar take-off/landing mat is presented. This proposal goes beyond dealing with the usual problems of heat and load resistances associated with take-off and landing, by solving the problem of soil stabilization at the site. Through adequate stabilization, the problem of flying debris is eliminated.

  3. Fuel and Emissions Reduction in Electric Power Take-Off Equipped Utility Vehicles

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

    Konan, Arnaud; Ragatz, Adam; Prohaska, Robert

    The National Renewable Energy Laboratory (NREL) evaluated the performance of Pacific Gas and Electric plug-in hybrid electric power take off (ePTO) utility trucks equipped with Altec, Inc.'s Jobsite Energy Management System. NREL collected on-road performance data from Class 5 utility 'trouble trucks' and Class 8 material handlers and developed representative drive cycles for chassis dynamometer testing. The drive cycles were analyzed and jobsite energy use was quantified for impacts and potential further hybridization for the utility truck vocation.

  4. Take Off! Aeronautics and Aviation Science: Careers and Opportunities

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Funded by National Aeronautic and Space Administration's High Performance Computing and Communications/ Learning Technologies Project (HPCC/LTP) Cooperative Agreement, Aeronautics and aviation Science: Careers and Opportunities was operative from July 1995 through July 1998. This project operated as a collaboration with Massachusetts Corporation for Educational Telecommunications, the Federal Aviation Administration, Bridgewater State College and four targeted "core sites" in the greater Boston area: Dorchester, Malden, East Boston and Randolph. In its first and second years, a video series with a participatory website on aeronautics and aviation science was developed and broadcast via "live, interactive" satellite feed. Accompanying teacher and student supplementary instructional materials for grades 6-12 were produced and disseminated by the Massachusetts Corporation for Educational Telecommunications (MCET). In year three, the project team redesigned the website, edited 14 videos to a five part thematic unit, and developed a teacher's guide to the video and web materials supplement for MAC and PC platforms, aligned with national standards. In the MCET grant application it states that project Take Off! in its initial phase would recruit and train teachers at "core" sites in the greater Boston area, as well as opening participation to other on-line users of MCET's satellite feeds. "Core site" classrooms would become equipped so that teachers and students might become engaged in an interactive format which aimed at not only involving the students during the "live" broadcast of the instructional video series, but which would encourage participation in electronic information gathering and sharing among participants. As a Take Off! project goal, four schools with a higher than average proportion of minority and underrepresented youth were invited to become involved with the project to give these students the opportunity to consider career exploration and development

  5. Regional biases in absolute sea-level estimates from tide gauge data due to residual unmodeled vertical land movement

    NASA Astrophysics Data System (ADS)

    King, Matt A.; Keshin, Maxim; Whitehouse, Pippa L.; Thomas, Ian D.; Milne, Glenn; Riva, Riccardo E. M.

    2012-07-01

    The only vertical land movement signal routinely corrected for when estimating absolute sea-level change from tide gauge data is that due to glacial isostatic adjustment (GIA). We compare modeled GIA uplift (ICE-5G + VM2) with vertical land movement at ˜300 GPS stations located near to a global set of tide gauges, and find regionally coherent differences of commonly ±0.5-2 mm/yr. Reference frame differences and signal due to present-day mass trends cannot reconcile these differences. We examine sensitivity to the GIA Earth model by fitting to a subset of the GPS velocities and find substantial regional sensitivity, but no single Earth model is able to reduce the disagreement in all regions. We suggest errors in ice history and neglected lateral Earth structure dominate model-data differences, and urge caution in the use of modeled GIA uplift alone when interpreting regional- and global- scale absolute (geocentric) sea level from tide gauge data.

  6. An investigation into the vertical axis control power requirements for landing VTOL type aircraft onboard nonaviation ships in various sea states

    NASA Technical Reports Server (NTRS)

    Stevens, M. E.; Roskam, J.

    1985-01-01

    The problem of determining the vertical axis control requirements for landing a VTOL aircraft on a moving ship deck in various sea states is examined. Both a fixed-base piloted simulation and a nonpiloted simulation were used to determine the landing performance as influenced by thrust-to-weight ratio, vertical damping, and engine lags. The piloted simulation was run using a fixed-based simulator at Ames Research center. Simplified versions of an existing AV-8A Harrier model and an existing head-up display format were used. The ship model used was that of a DD963 class destroyer. Simplified linear models of the pilot, aircraft, ship motion, and ship air-wake turbulence were developed for the nonpiloted simulation. A unique aspect of the nonpiloted simulation was the development of a model of the piloting strategy used for shipboard landing. This model was refined during the piloted simulation until it provided a reasonably good representation of observed pilot behavior.

  7. Perception of the upright and susceptibility to motion sickness as functions of angle of tilt and angular velocity in off-vertical rotation. [human tolerance to angular accelerations

    NASA Technical Reports Server (NTRS)

    Miller, E. F., II; Graybiel, A.

    1973-01-01

    Motion sickness susceptibility of four normal subjects was measured in terms of duration of exposure necessary to evoke moderate malaise (MIIA) as a function of velocity in a chair rotated about a central axis tilted 10 deg with respect to gravitational upright. The subjects had little or no susceptibility to this type of rotation at 2.5 and 5.0 rpm, but with further increases in rate, the MIIA endpoint was always reached and with ever shorter test durations. Minimal provocative periods for all subjects were found at 15 or 20 rpm. Higher rotational rates dramatically reversed the vestibular stressor effect, and the subjects as a group tended to reach a plateau of relatively low susceptibility at 40 and 45 rpm. At these higher velocities, furthermore, the subjects essentially lost their sensation of being tilted off vertical. In the second half of the study, the effect of tilt angle was varied while the rotation rate was maintained at a constant 17.5 rpm. Two subjects were completely resistant to symptoms of motion sickness when rotated at 2.5 deg off vertical; with greater off-vertical angles, the susceptibility of all subjects increased sharply at first, then tapered off in a manner reflecting a Fechnerian function.

  8. NASA's DC-8 Airborne Science research aircraft, in new colors and markings, takes off Feb. 24, 2004

    NASA Image and Video Library

    2004-02-24

    NASA's DC-8 Airborne Science research aircraft, in new colors and markings, takes off Feb. 24, 2004. Dark panels on lower fuselage are synthetic aperture radar antennas enabling sophisticated studies of Earth features.

  9. Environmental effects of off-highway vehicles on Bureau of Land Management lands: A literature synthesis, annotated bibliographies, extensive bibliographies, and internet resources

    USGS Publications Warehouse

    Ouren, Douglas S.; Haas, Christopher; Melcher, Cynthia P.; Stewart, Susan C.; Ponds, Phadrea D.; Sexton, Natalie R.; Burris, Lucy; Fancher, Tammy; Bowen, Zachary H.

    2007-01-01

    This report and its associated appendixes compile and synthesize the results of a comprehensive literature and Internet search conducted in May 2006. The literature search was undertaken to uncover information regarding the effects of off-highway vehicle (OHV) use on land health, or “natural resource attributes,” and included databases archiving information from before OHVs came into existence to May 2006. Information pertaining to socioeconomic implications of OHV activities is included as well. The literature and Internet searches yielded approximately 700 peer-reviewed papers, magazine articles, agency and non-governmental reports, and internet websites regarding effects of OHV use as they relate to the Bureau of Land Management’s (BLM) standards of land health. Discussions regarding OHV effects are followed by brief syntheses of potential indicators of OHV effects, as well as OHV-effects mitigation, site-restoration techniques, and research needs.

  10. A study of rotor and platform design trade-offs for large-scale floating vertical axis wind turbines

    NASA Astrophysics Data System (ADS)

    Griffith, D. Todd; Paquette, Joshua; Barone, Matthew; Goupee, Andrew J.; Fowler, Matthew J.; Bull, Diana; Owens, Brian

    2016-09-01

    Vertical axis wind turbines are receiving significant attention for offshore siting. In general, offshore wind offers proximity to large populations centers, a vast & more consistent wind resource, and a scale-up opportunity, to name a few beneficial characteristics. On the other hand, offshore wind suffers from high levelized cost of energy (LCOE) and in particular high balance of system (BoS) costs owing to accessibility challenges and limited project experience. To address these challenges associated with offshore wind, Sandia National Laboratories is researching large-scale (MW class) offshore floating vertical axis wind turbines (VAWTs). The motivation for this work is that floating VAWTs are a potential transformative technology solution to reduce offshore wind LCOE in deep-water locations. This paper explores performance and cost trade-offs within the design space for floating VAWTs between the configurations for the rotor and platform.

  11. Noise of the Harrier in vertical landing and takeoff

    NASA Technical Reports Server (NTRS)

    Soderman, Paul T.; Foster, John D.

    1988-01-01

    The noise of the Harrier AV8C aircraft in vertical takeoff and landing was measured 100 feet to the side of the aircraft where jet noise dominates. The noise levels were quite high - up to 125 dB overall sound level at 100 feet. The increased noise due to jet impingement on the ground is presented as a function of jet height to diameter ratio. The impingement noise with the aircraft close to the ground was 14 to 17 dB greater than noise from a free jet. Results are compared with small-scale jet impingement data acquired elsewhere. The agreement between small-scale and full-scale noise increase in ground effect is fairly good except with the jet close to the ground. It is proposed that differences in the jet Reynolds numbers and the resultant character of the jets may be partially responsible for the disparity in the full-scale and small-scale jet impingement noise. The difference between single-jet impingement and multiple-jet impingement may also have been responsible for the small-scale and full-scale disagreement.

  12. Coastal sea level projections with improved accounting for vertical land motion

    PubMed Central

    Han, Guoqi; Ma, Zhimin; Chen, Nan; Yang, Jingsong; Chen, Nancy

    2015-01-01

    Regional and coastal mean sea level projections in the Intergovernmental Panel for Climate Change (IPCC) Fifth Assessment Report (AR5) account only for vertical land motion (VLM) associated with glacial isostatic adjustment (GIA), which may significantly under- or over-estimate sea level rise. Here we adjust AR5-like regional projections with the VLM from Global Positioning Satellite (GPS) measurements and/or from a combination of altimetry and tide-gauge data, which include both GIA and non-GIA VLM. Our results at selected tide-gauge locations on the North American and East Asian coasts show drastically different projections with and without non-GIA VLM being accounted for. The present study points to the importance of correcting IPCC AR5 coastal projections for the non-GIA VLM in making adaptation decisions. PMID:26526287

  13. Coastal sea level projections with improved accounting for vertical land motion.

    PubMed

    Han, Guoqi; Ma, Zhimin; Chen, Nan; Yang, Jingsong; Chen, Nancy

    2015-11-03

    Regional and coastal mean sea level projections in the Intergovernmental Panel for Climate Change (IPCC) Fifth Assessment Report (AR5) account only for vertical land motion (VLM) associated with glacial isostatic adjustment (GIA), which may significantly under- or over-estimate sea level rise. Here we adjust AR5-like regional projections with the VLM from Global Positioning Satellite (GPS) measurements and/or from a combination of altimetry and tide-gauge data, which include both GIA and non-GIA VLM. Our results at selected tide-gauge locations on the North American and East Asian coasts show drastically different projections with and without non-GIA VLM being accounted for. The present study points to the importance of correcting IPCC AR5 coastal projections for the non-GIA VLM in making adaptation decisions.

  14. Land Conservation in an Evolving Agricultural Industry: Trade-offs to Consider

    NASA Astrophysics Data System (ADS)

    Baker, J. S.; Murray, B. C.; McCarl, B. A.; Jackson, R. B.

    2008-12-01

    practices (exhibiting a 53.4% reversion rate). This reversion is a logical, low cost extensification of crop land; higher reversion rates are observed where agricultural land is most valuable, such as in Iowa and Illinois. Forecasted CRP re-cultivation accompanies environmental degradation in the form of increased chemical applications, irrigation water use and soil erosion relative to the baseline. However, if the CRP is maintained at current levels then this would shift LUC to other conversions, including a greater loss of forest amounting to 6.3 million acres relative to a case where land in CRP freely reverts. This increase in deforestation is likely to spill over into other countries as well. The net carbon loss of deforested land negates the carbon benefits of maintaining the CRP in its current state. Thus, while the environmental impacts of re-cultivating conservation lands are potentially serious, maintaining the CRP in its current form could induce LUC and even greater GHG and environmental emissions. The study concludes by discussing the environmental and economic trade-offs of land conservation under the aforementioned scenarios, and offers policy recommendations for future land conservation initiatives.

  15. Living Off The Land On Mars keynote presentation for Discovery On Parade event

    NASA Technical Reports Server (NTRS)

    Leucht, Kurt

    2017-01-01

    The subject keynote presentation is per NASA HQS approved Speakers Bureau Event 17-00232. The requestor and event sponsor, Florida State University, is paying for lodging and meals and the NASA Speakers Bureau is paying any other costs. The attached document is the keynote presentation titled Living Off The Land On Mars which will be presented at the 10th Annual Discovery On Parade technology transfer trade show on February 7th, 2017 in Tallahassee Florida.

  16. Orbit on demand - Structural analysis finds vertical launchers weigh less

    NASA Technical Reports Server (NTRS)

    Taylor, A. H.; Cruz, C. I.; Jackson, L. R.; Naftel, J. C.; Wurster, K. E.; Cerro, J. A.

    1985-01-01

    Structural considerations arising from favored design concepts for the next generation on-demand launch vehicles are explored. The two emerging concepts are a two stage fully reusable vertical take-off vehicle (V-2) and a horizontal take-off, two stage subsonic boost launch vehicle (H-2-Sub). Both designs have an 1100 n. mi. cross-range capability, with the V-2 orbiter having small wings with winglets for hypersonic trim and the H-2-Sub requiring larger, swept wings. The rockets would be cryogenic, while airbreathing initial boosters would be either turbofans, turbojets and/or ramjets. Dynamic loading is lower in the launch of a V-2. The TPS is a critical factor due to thinner leading edges than on the Shuttle and may require heat-pipe cooling. Airframe structures made of metal matrix composites have passed finite element simulations of projected loads and can now undergo proof-of-concept tests, although whisker-reinforced materials may be superior once long-whisker technology is developed.

  17. Ground noise measurements during landing, take-off, and flyby operations of a four-engine turbopropeller STOL airplane

    NASA Technical Reports Server (NTRS)

    Hilton, D. A.; Henderson, H. R.; Maglieri, D. J.

    1971-01-01

    Noise measurements were obtained for a four-engine turbopropeller STOL airplane during a Federal Aviation Administration flight evaluation program at the National Aviation Facilities Experimental Center. These noise measurements involved landing-approach, takeoff-climbout, and flyby operations of the airplane. A total of 13 measuring positions were used to define the noise characteristics around a simulated STOL port. The results are presented in the form of both physical and subjective measurements. An appendix is included to present tabulated values of various subjective reaction units which may be significant for the planning and operation of STOL ports. The main source of noise produced by this vehicle was found to be the propeller, and noise levels decrease generally in accordance with the inverse-distance law for distances up to about 457 meters. For similar slant ranges, somewhat lower noise levels were experienced during flyby than during takeoff or landing.

  18. Demonstrations of bio-inspired perching landing gear for UAVs

    NASA Astrophysics Data System (ADS)

    Tieu, Mindy; Michael, Duncan M.; Pflueger, Jeffery B.; Sethi, Manik S.; Shimazu, Kelli N.; Anthony, Tatiana M.; Lee, Christopher L.

    2016-04-01

    Results are presented which demonstrate the feasibility and performance of two concepts of biologically-inspired landing-gear systems that enable bird-sized, unmanned aerial vehicles (UAV's) to land, perch, and take-off from branchlike structures and/or ledges. The first concept follows the anatomy of birds that can grasp ahold of a branch and perch as tendons in their legs are tensioned. This design involves a gravity-activated, cable-driven, underactuated, graspingfoot mechanism. As the UAV lands, its weight collapses a four-bar linkage pulling a cable which curls two opposing, multi-segmented feet to grasp the landing target. Each foot is a single, compliant mechanism fabricated by simultaneouly 3D-printing a flexible thermo-plastic and a stiffer ABS plastic. The design is optimized to grasp structures over a range of shapes and sizes. Quasi-static and flight tests of this landing gear affixed to RC rotorcraft (24 cm to 550 cm in diameter) demonstrate that the aircraft can land, perch, and take-off from a tree branch, rectangular wood board, PVC pipe, metal hand rail, chair armrest, and in addition, a stone wall ledge. Stability tests show that perching is maintained under base and wind disturbances. The second design concept, inspired by roosting bats, is a two-material, 3D-printed hooking mechanism that enables the UAV to stably suspend itself from a wire or small-diameter branch. The design balances structural stiffness for support and flexibility for the perching process. A flight-test demonstrates the attaching and dis-engaging of a small, RC quadcopter from a suspended line.

  19. Wind-Tunnel Tests of the 1/9-Scale Model of the Curtiss XP-62 Airplane with Various Vertical Tail Arrangements

    NASA Technical Reports Server (NTRS)

    Wallace, Arthur R.; Recant, I.G.

    1943-01-01

    The effect of various vertical tail arrangements upon the stability and control characteristics of an XP-62 fighter model was investigated. Rudder-free yaw characteristics with take-off power and flaps deflected were satisfactory after dorsal fin modifications. Directional stability was obtained with all modified vertical tails. Satisfactory rudder effectiveness resulted partly because the dual-rotation propellers produced no asymmetric yawing moments. Pedal forces in sideslips were undesirably large but may be easily reduced.

  20. The Impact of Land Use and Land Cover Change on Water Yield in the Jing- Jin-Ji Region in China

    NASA Astrophysics Data System (ADS)

    Li, Suxiao; Yang, Hong

    2017-04-01

    Water yield is one of the key ecosystem services sustaining both people's life and economic development. However, the water yield function is sensitive to anthropogenic activity especially the land use and land cover change (LUCC). Assessment of historical LUCC and its impact on water yield could benefit designing and implementing appropriate land use strategy that enhance the water yield capacity. Beijing (Jing) and its surrounding areas of Tianjin (Jin) and Hebei (Ji) is the political, cultural and economic center of China. The region is facing increasingly water crisis. Taking the Jing-Jin-Ji region as a study area, this study analyzed the historical LUCC and its impact on water yield by using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model to spatially map and quantify the changes of water yield from 1995 to 2010. The results showed there was main decline in area of wetland and forest and increase in area of crop land and built up land. An abrupt decline in water yield was found for year 2000. The water yield was influenced to a great extent by precipitation and evapotranspiration, but the land use played an important role in the water yield capacity (water yield per unit area) through plant cover that affected evapotranspiration, soil water permeability and the capacity of holding the moisture content. By general ranking, the water yield capacity of different land use type was as follows: built-up>bare land>cropland> grassland>forest >wetland, which illustrated that the built-up and bare land had higher run off rate while the vegetation area had higher capacity to control surface run off to increase the groundwater. A good understanding of temporal-spatial allocation of historical LUCC and Water yield of the Jing-Jin-Ji region could help guide land use policy decisions that take into consideration of tradeoffs with respect to spatial distribution of ecosystem services amongst the three administrative entities (Jing-Jin-Ji) and

  1. Risk-based design of process plants with regard to domino effects and land use planning.

    PubMed

    Khakzad, Nima; Reniers, Genserik

    2015-12-15

    Land use planning (LUP) as an effective and crucial safety measure has widely been employed by safety experts and decision makers to mitigate off-site risks posed by major accidents. Accordingly, the concept of LUP in chemical plants has traditionally been considered from two perspectives: (i) land developments around existing chemical plants considering potential off-site risks posed by major accidents and (ii) development of existing chemical plants considering nearby land developments and the level of additional off-site risks the land developments would be exposed to. However, the attempts made to design chemical plants with regard to LUP requirements have been few, most of which have neglected the role of domino effects in risk analysis of major accidents. To overcome the limitations of previous work, first, we developed a Bayesian network methodology to calculate both on-site and off-site risks of major accidents while taking domino effects into account. Second, we combined the results of risk analysis with Analytic Hierarchical Process to design an optimal layout for which the levels of on-site and off-site risks would be minimum. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Using GPS Imaging to Unravel Vertical Land Motions in the Interior Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Overacker, J.; Hammond, W. C.; Kraner, M.; Blewitt, G.

    2017-12-01

    GPS Imaging uses robust trends in time series of GPS positions to create a velocity field that can reveal rates and patterns of vertical motions that would be otherwise difficult to detect. We have constructed an image of vertical land velocities within the interior Pacific Northwest region of the United States using GPS Imaging. The image shows a 50-250 km wide swath of approximately 2 mm/yr of subsidence seemingly unrelated to topographic features of the region. The extent of the signal roughly corresponds to the Juan de Fuca plate subduction latitudes and longitude of the Cascade arc. This suggests that the signal could be associated with ongoing crustal deformation possibly related to plate-scale geodynamic forces arising from interseismic coupling, long term plate boundary tractions, volcanic loading, and/or mantle flow. However, hydrological loading from accumulating precipitation in the Cascades and in the region's groundwater basins, and possible effects from Glacial Isostatic Adjustment (GIA) near its hinge line cannot be discounted as potential contributors to the observed subsidence signal. Here we attempt to unravel the contributions of hydrological loading and GIA to the vertical GPS signal observed within the interior Pacific Northwest. In order to determine the non-tectonic contributions to the observed vertical GPS Image, we will examine how the subsidence rate changes over time using early and late period comparisons. GPS, GRACE, and climatic data will be used in conjunction to disentangle the hydrological effect from the GPS Image. GIA models of the Western Cordillera will be compared with the patterns in the GPS Image to assess whether the signal can be explained with current models of GIA. Our presentation will document the signals, uncertainties, and hypotheses for the possible mechanisms behind this subsidence and attempt to quantify their relation and contribution to the observed deformation signal. Figure 1: Pacific Northwest GPS Imaging

  3. DC-9 V/STOL Transport Model in the 40x80 Foot Wind Tunnel.

    NASA Image and Video Library

    1971-04-28

    3/4 front view of McDonnell-Douglas Large-Scale lift fan, vertical and/or short take-off and landing (V/STOL), transport model. Francis Malerick in photograph. The McDonnell Douglas DC-9 (initially known as the Douglas DC-9) is a twin-engine, single-aisle jet airliner.

  4. Representative learning design in springboard diving: Is dry-land training representative of a pool dive?

    PubMed

    Barris, Sian; Davids, Keith; Farrow, Damian

    2013-01-01

    Two distinctly separate training facilities (dry-land and aquatic) are routinely used in springboard diving and pose an interesting problem for learning, given the inherent differences in landing (head first vs. feet first) imposed by the different task constraints. Although divers may practise the same preparation phase, take-off and initial aerial rotation in both environments, there is no evidence to suggest that the tasks completed in the dry-land training environment are representative of those performed in the aquatic competition environment. The aim of this study was to compare the kinematics of the preparation phase of reverse dives routinely practised in each environment. Despite their high skill level, it was predicted that individual analyses of elite springboard divers would reveal differences in the joint coordination and board-work between take-offs. The two-dimensional kinematic characteristics were recorded during normal training sessions and used for intra-individual analysis. Kinematic characteristics of the preparatory take-off phase revealed differences in board-work (step lengths, jump height, board depression angles) for all participants at key events. However, the presence of scaled global topological characteristics suggested that all participants adopted similar joint coordination patterns in both environments. These findings suggest that the task constraints of wet and dry training environments are not similar, and highlight the need for coaches to consider representative learning designs in high performance diving programmes.

  5. Risk ON/Risk OFF: Risk-Taking Varies with Subjectively Preferred and Disliked Music.

    PubMed

    Halko, Marja-Liisa; Kaustia, Markku

    2015-01-01

    In this paper we conduct a within-subjects experiment in which teenagers go over 256 gambles with real money gains and losses. For each risky gamble they choose whether to participate in it, or pass. Prior to this main experiment subjects identify specific songs belonging to their favorite musical genre, as well as songs representing a style they dislike. In the main experiment we vary the music playing in the background, so that each subject hears some of their favorite music, and some disliked music, alternating in blocks of 16 gambles. We find that favorite music increases risk-taking ('risk on'), and disliked music suppresses risk-taking ('risk off'), compared to a baseline of no music. Literature in psychology proposes several mechanisms by which mood affects risk-taking, but none of them fully explain the results in our setting. The results are, however, consistent with the economics notion of preference complementarity, extended to the domain of risk preference. The preference structure implied by our results is more complex than previously thought, yet realistic, and consistent with recent theoretical models. More generally, this mechanism offers a potential explanation to why risk-taking is known to change over time and across contexts.

  6. Using continuous GPS and absolute gravity to separate vertical land movements and changes in sea-level at tide-gauges in the UK.

    PubMed

    Teferle, F N; Bingley, R M; Williams, S D P; Baker, T F; Dodson, A H

    2006-04-15

    Researchers investigating climate change have used historical tide-gauge measurements from all over the world to investigate the changes in sea-level that have occurred over the last century or so. However, such estimates are a combination of any true sea-level variations and any vertical movements of the land at the specific tide-gauge. For a tide- gauge record to be used to determine the climate related component of changes in sea-level, it is therefore necessary to correct for the vertical land movement component of the observed change in sea-level.In 1990, the Institute of Engineering Surveying and Space Geodesy and Proudman Oceanographic Laboratory started developing techniques based on the Global Positioning System (GPS) for measuring vertical land movements (VLM) at tide-gauges in the UK. This paper provides brief details of these early developments and shows how they led to the establishment of continuous GPS (CGPS) stations at a number of tide-gauges. The paper then goes on to discuss the use of absolute gravity (AG), as an independent technique for measuring VLM at tide-gauges. The most recent results, from CGPS time-series dating back to 1997 and AG time-series dating back to 1995/1996, are then used to demonstrate the complementarity of these two techniques and their potential for providing site-specific estimates of VLM at tide-gauges in the UK.

  7. Detection of stratosphere troposphere exchange in cut-off low systems

    NASA Technical Reports Server (NTRS)

    Price, Jeremy D.; Vaughan, Geraint

    1994-01-01

    The Aberystwyth MST radar has been used as part of the TOASTE program to study the structure of the tropopause in cut-off-low system with an aim to identifying regions where stratosphere-troposphere exchange are taking place. Theory predicts that the vertical gradient in reflected power is proportional to the static stability of the reflecting region, and should therefore resolve tropopause structure. Comparisons of MST power profiles with radiosonde data are presented and show good agreement, revealing regions of indefinite tropopauses, where stratosphere-troposphere exchange is thought to take place. The continuous nature of MST data allows an estimation of the size of these regions.

  8. Trends in federal land acquisition, protection strategies, and planning

    Treesearch

    Warren Brown

    1980-01-01

    In the past, Federal land acquisition has been one of the most popular ways to protect outstanding natural resources and provide recreational opportunities. Federal purchase, maintenance, and operation can help take pressure off the State or local budget. Federal involvement also can provide a way for local officials to avoid making some tough decisions about...

  9. [Discussion on reduction potential of CH4 emission intensity for early off-take practice of grazing yak].

    PubMed

    Wang, Shi-Ping; Wilkes, Andreas; Wang, Ya-Yun; Bai, Ling

    2014-08-01

    The case study preliminarily compared the CH4 reduction potential and CH4 emission intensity of 7 year-old and 4 year-old grazing yak after early off-take practice based on the 2006 IPCC GHG inventory guidelines and under the premise of equal herbage consumption. Our results showed that the total CH4 emission was greater by about 86.3 kg for 2.1 4-year yaks compared with 7 years old yak during their life assuming that their total herbage consumption was the same, because total herbage consumption for a 7-year yak was equal to that of 2.1 4-year yaks. However, CH4 emission per unit body weight (1.374 kg x kg(-1)) for a 7-year yak (i. e. emission intensity) was higher than that of 2.1 4-year yaks (0.973 kg x kg(-1)) because total body weight of 2.1 4-year yaks was higher by 192 kg than that of a 7-year yak. According to CH4 emission intensity, change of the early off-take practice from 7-year to 4-year yak could reduce 77 kg CH4 if producing 192 kg body weight through 2.1 4-year yaks compared with a 7-year yak, i. e. reduction potential was about 1 600 kg CO2 equivalent under the same consuming forage. Therefore, for grassland-based animal husbandry, early off-take practice for grazing animals had a great reduction potential in the intensity of greenhouse gases (GHGs) emissions per unit output rather than total emissions of GHGs.

  10. Evolution of engine cycles for STOVL propulsion concepts

    NASA Technical Reports Server (NTRS)

    Bucknell, R. L.; Frazier, R. H.; Giulianetti, D. J.

    1990-01-01

    Short Take-off, Vertical Landing (STOVL) demonstrator concepts using a common ATF engine core are discussed. These concepts include a separate fan and core flow engine cycle, mixed flow STOVL cycles, separate flow cycles convertible to mixed flow, and reaction control system engine air bleed. STOVL propulsion controls are discussed.

  11. Relationship between different push-off variables and start performance in experienced swimmers.

    PubMed

    García-Ramos, Amador; Feriche, Belén; de la Fuente, Blanca; Argüelles-Cienfuegos, Javier; Strojnik, Vojko; Strumbelj, Boro; Štirn, Igor

    2015-01-01

    The objective of this study was to determine the relationship between different variables measured with a force plate during the swimming start push-off phase and start performance presented by times to 5, 10 and 15 m. Twenty-one women from the Slovenian national swimming team performed two different swim starts (freestyle and undulatory) on a portable force plate to a distance further than 15 m. Correlations between push-off variables and times to 5, 10 and 15 m were quantified through Pearson's product-moment correlation coefficient (r). The variables that significantly correlated (p < .05) to all times measured in the two starts performed were: average horizontal acceleration (freestyle: r = -0.58 to -0.71; and undulatory: r = -0.55 to -0.66), horizontal take-off velocity (freestyle: r = -0.56 to -0.69; and undulatory: r = -0.53 to -0.67) and resultant take-off velocity (freestyle: r = -0.53 to -0.65; and undulatory: r = -0.52 to -0.61). None of the variables derived from the vertical force were correlated to swimming start performance (p > .05). Based on the results of this study, we can conclude that horizontal take-off velocity and average horizontal acceleration (calculated as the average horizontal force divided by swimmer's body mass) are the variables most related to swimming start performance in experienced swimmers, and therefore could be the preferred measures to monitor swimmers' efficiency during the push-off phase.

  12. Off-plane polarization ordering in metal chalcogen diphosphates from bulk to monolayer

    NASA Astrophysics Data System (ADS)

    Song, Wenshen; Fei, Ruixiang; Yang, Li

    2017-12-01

    Vertically (off-plane) ferroelectric ordering in ultrathin films has been pursued for decades. We predict the existence of intrinsic vertical polarization orderings in ultrathin metal chalcogen-diphosphates (MCDs). Taking CuInP2Se6 as an example, the first-principles calculation and electrostatic-energy model show that, under the open-circuit boundary condition, the ground state of bulk CuInP2Se6 is ferroelectric (FE) while that of monolayer is antiferroelectric (AFE), and the critical thickness for this FE/AFE transition is around six layers. Interestingly, under the closed-circuit boundary condition, the FE state can hold even for monolayer. Particularly, because of the small energy difference but the large barrier between FE and AFE orderings, the FE state can be stabilized in a free-standing monolayer, giving rise to intrinsic, off-plane two-dimensional ferroelectrics. Applying Monte Carlo simulations, we further calculate the ferroelectric Curie temperature (Tc) and electric hysteresis.

  13. How is the brain working?: Research on brain oscillations and connectivities in a new "Take-Off" state.

    PubMed

    Başar, Erol; Düzgün, Aysel

    2016-05-01

    The present report is a trial to survey analysis and applications of brain oscillations in cognitive impairment for opening the way to a new take off in research on brain oscillation. Although the number of papers related to brain oscillations rapidly increases, it is important to indicate the common principles governing the functioning of brain oscillations in the brain and body. Research scientists need a global view on the types of analysis, applications and existing oscillations. Further, scientists dealing with brain oscillations must have some knowledge from theoretical physics, system theory, and also general philosophy. The neuroscientists working on brain oscillations can mentally integrate several papers in the present report, and try to discover new avenues to augment knowledge on brain functions. A new take off in the search of brain oscillations indicates the strong need to survey this brunch of neuroscience in a broad panoply of science. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  14. Intra-specific variation in wing morphology and its impact on take-off performance in blue tits (Cyanistes caeruleus) during escape flights

    PubMed Central

    McFarlane, Laura; Altringham, John D.; Askew, Graham N.

    2016-01-01

    ABSTRACT Diurnal and seasonal increases in body mass and seasonal reductions in wing area may compromise a bird's ability to escape, as less of the power available from the flight muscles can be used to accelerate and elevate the animal's centre of mass. Here, we investigated the effects of intra-specific variation in wing morphology on escape take-off performance in blue tits (Cyanistes caeruleus). Flights were recorded using synchronised high-speed video cameras and take-off performance was quantified as the sum of the rates of change of the kinetic and potential energies of the centre of mass. Individuals with a lower wing loading, WL (WL=body weight/wing area) had higher escape take-off performance, consistent with the increase in lift production expected from relatively larger wings. Unexpectedly, it was found that the total power available from the flight muscles (estimated using an aerodynamic analysis) was inversely related to WL. This could simply be because birds with a higher WL have relatively smaller flight muscles. Alternatively or additionally, variation in the aerodynamic load on the wing resulting from differences in wing morphology will affect the mechanical performance of the flight muscles via effects on the muscle's length trajectory. Consistent with this hypothesis is the observation that wing beat frequency and relative downstroke duration increase with decreasing WL; both are factors that are expected to increase muscle power output. Understanding how wing morphology influences take-off performance gives insight into the potential risks associated with feather loss and seasonal and diurnal fluctuations in body mass. PMID:26994175

  15. Ocular Reflex Phase During Off-Vertical Axis Rotation In Humans Is Modified By Head-On-Trunk Position

    NASA Technical Reports Server (NTRS)

    Wood, Scott; Clement, Gilles; Denise, Pierre; Reschke, Millard

    2005-01-01

    Constant velocity Off-Vertical Axis Rotation (OVAR) imposes a continuously varying orientation of the head and body relative to gravity. The ensuing ocular reflexes include modulation of both horizontal and torsional eye velocity as a function of the varying linear acceleration along the lateral plane. The purpose of this study was to examine whether the modulation of these ocular reflexes would be modified by different head-on-trunk positions. Ten human subjects were rotated in darkness about their longitudinal axis 20 deg off-vertical at constant rates of 45 and 180 deg/s, corresponding to 0.125 and 0.5 Hz. Binocular responses were obtained with video-oculography with the head and trunk aligned, and then with the head turned relative to the trunk 40 deg to the right or left of center. Sinusoidal curve fits were used to derive amplitude, phase and bias velocity of the eye movements across multiple cycles for each head-on-trunk position. Consistent with previous studies, the modulation of torsional eye movements was greater at 0.125 Hz while the modulation of horizontal eye movements was greater at 0.5 Hz. Neither amplitude nor bias velocities were significantly altered by head-on-trunk position. The phases of both torsional and horizontal ocular reflexes, on the other hand, shifted towards alignment with the head. These results are consistent with the modulation of torsional and horizontal ocular reflexes during OVAR being primarily mediated by the otoliths in response to the sinusoidally varying linear acceleration along the interaural head axis.

  16. Flight Investigation of Effects of Transition, Landing Approaches, Partial-Power Vertical Descents, and Droop-Stop Pounding on the Bending and Torsional Moments Encountered by a Helicopter Rotor Blade

    NASA Technical Reports Server (NTRS)

    Ludi, LeRoy H.

    1959-01-01

    Flight tests have been conducted with a single-rotor helicopter, one blade of which was equipped at 14 percent and 40 percent of the blade radius with strain gages calibrated to measure moments rather than stresses, to determine the effects of transition, landing approaches, and partial-power vertical descents on the rotor-blade bending and torsional moments. In addition, ground tests were conducted to determine the effects of static droop-stop pounding on the rotor-blade moments. The results indicate that partial-power vertical descents and landing approaches produce rotor-blade moments that are higher than the moments encountered in any other flight condition investigated to date with this equipment. Decelerating through the transition region in level flight was found to result in higher vibratory moments than accelerating through this region. Deliberately induced static droop-stop pounding produced flapwise bending moments at the 14-percent-radius station which were as high as the moments experienced in landing approaches and partial-power vertical descents.

  17. Surface Hydrology in Global River Basins in the Off-Line Land-Surface GEOS Assimilation (OLGA) System

    NASA Technical Reports Server (NTRS)

    Bosilovich, Michael G.; Yang, Runhua; Houser, Paul R.

    1998-01-01

    Land surface hydrology for the Off-line Land-surface GEOS Analysis (OLGA) system and Goddard Earth Observing System (GEOS-1) Data Assimilation System (DAS) has been examined using a river routing model. The GEOS-1 DAS land-surface parameterization is very simple, using an energy balance prediction of surface temperature and prescribed soil water. OLGA uses near-surface atmospheric data from the GEOS-1 DAS to drive a more comprehensive parameterization of the land-surface physics. The two global systems are evaluated using a global river routing model. The river routing model uses climatologic surface runoff from each system to simulate the river discharge from global river basins, which can be compared to climatologic river discharge. Due to the soil hydrology, the OLGA system shows a general improvement in the simulation of river discharge compared to the GEOS-1 DAS. Snowmelt processes included in OLGA also have a positive effect on the annual cycle of river discharge and source runoff. Preliminary tests of a coupled land-atmosphere model indicate improvements to the hydrologic cycle compared to the uncoupled system. The river routing model has provided a useful tool in the evaluation of the GCM hydrologic cycle, and has helped quantify the influence of the more advanced land surface model.

  18. Elite long jumpers with below the knee prostheses approach the board slower, but take-off more effectively than non-amputee athletes.

    PubMed

    Willwacher, Steffen; Funken, Johannes; Heinrich, Kai; Müller, Ralf; Hobara, Hiroaki; Grabowski, Alena M; Brüggemann, Gert-Peter; Potthast, Wolfgang

    2017-11-22

    The use of technological aids to improve sport performance ('techno doping') and inclusion of Paralympic athletes in Olympic events are matters of ongoing debate. Recently, a long jumper with a below the knee amputation (BKA) achieved jump distances similar to world-class athletes without amputations, using a carbon fibre running-specific prosthesis (RSP). We show that athletes with BKA utilize a different, more effective take-off technique in the long jump, which provided the best athlete with BKA a performance advantage of at least 0.13 m compared to non-amputee athletes. A maximum speed constraint imposed by the use of RSPs would indicate a performance disadvantage for the long jump. We found slower maximum sprinting speeds in athletes with BKA, but did not find a difference in the overall vertical force from both legs of athletes with BKA compared to non-amputees. Slower speeds might originate from intrinsically lower sprinting abilities of athletes with BKA or from more complex adaptions in sprinting mechanics due to the biomechanical and morphological differences induced by RSPs. Our results suggest that due to different movement strategies, athletes with and without BKA should likely compete in separate categories for the long jump.

  19. Application of the concept of dynamic trim control and nonlinear system inverses to automatic control of a vertical attitude takeoff and landing aircraft

    NASA Technical Reports Server (NTRS)

    Smith, G. A.; Meyer, G.

    1981-01-01

    A full envelope automatic flight control system based on nonlinear inverse systems concepts has been applied to a vertical attitude takeoff and landing (VATOL) fighter aircraft. A new method for using an airborne digital aircraft model to perform the inversion of a nonlinear aircraft model is presented together with the results of a simulation study of the nonlinear inverse system concept for the vertical-attitude hover mode. The system response to maneuver commands in the vertical attitude was found to be excellent; and recovery from large initial offsets and large disturbances was found to be very satisfactory.

  20. On The Lookout: The Air Mobile Ground Security and Surveillance System (AMGSS) Has Arrived

    DTIC Science & Technology

    1995-01-01

    dimensional mobility allowed by the VTOL platform are ideally suited to this concept. If (during landing) there is loss of communications detected on the...vertical-take-off-and-landing, unmanned aircraft) with a sensor pod mounted on top as shown in figure 3. Projected weight of the mission-ready AMP...to restart the engine twice. Weight and power estimates are based on commercially available hardware, modified in some cases for the AMGSSS

  1. Living off the Land

    ERIC Educational Resources Information Center

    Dickerson, Peg; Gamberg, Maryellen

    2010-01-01

    Fourth-grade students at Cutchogue East Elementary School in Cutchogue, New York learned about dependence on natural resources for survival on a visit to Downs Farm Preserve at Fort Corchaug. This is a slice of preserved land just eight minutes beyond the classroom walls. Its inhabitants date back to the first hunting and gathering settlers--the…

  2. Snowboard jumping, Newton’s second law and the force on landing

    NASA Astrophysics Data System (ADS)

    O'Shea, Michael J.

    2004-07-01

    An application of Newton’s second law to a snowboarder dropping off a vertical ledge shows that the average normal force during landing (force exerted by the ground on the snowboarder) is determined by four factors. It is shown that the flexing of the legs, the softness of the snow, the angle of the landing surface and the forward motion of the snowboarder can contribute significantly to reducing the force on landing. A judicious choice of the geometry of the jump leads to a force on landing that is equal to the force that the snowboarder would feel if they were standing at the landing point independent of the height from which the snowboarder jumps. Thus we are able to explain with a relatively simple model why a snowboarder may jump from rather high ledges and land comfortably. The physics here is also applicable to jumps in other sports including skiing and mountain biking. The importance of knowing the limits of models is discussed and some of the limits of this model are pointed out.

  3. Development of new antibiotics: taking off finally?

    PubMed

    Bettiol, Esther; Harbarth, Stephan

    2015-01-01

    Since 2010, awareness of the global threat caused by antimicrobial resistance (AMR) has risen considerably and multiple policy and research initiatives have been implemented. Research and development (R&D) of much-needed new antibiotics active against multiresistant pathogens is a key component of all programmes aiming at fighting AMR, but it has been lagging behind owing to scientific, regulatory and economic challenges. Although a few new antibiotics might be available in Switzerland in the next 5 years, these new agents are not based on new mechanisms of action and are not necessarily active against resistant pathogens for which there is the highest unmet medical need, i.e. multiresistant Gram-negative bacteria. Of the three new antibiotics with pending authorisation in Switzerland for systemic treatment of severe infections, oritavancin and tedizolid target Gram-positive pathogens, while only ceftolozane+tazobactam partially covers multiresistant Gram-negative pathogens. Among six antibiotics currently in phase III of clinical development, delafloxacin and solithromycin will also be useful mostly for Gram-positive infections. Importantly, the four other compounds are active against multiresistant Gram-negative pathogens: ceftazidime+avibactam, meropenem+RPX7009, eravacycline and plazomicin. The three last compounds are also active against carbapenem-resistant Enterobacteriaceae (CRE). A few compounds active against such pathogens are currently in earlier clinical development, but their number may decrease, considering the risk of failure over the course of clinical development. At last, through public and political awareness of pathogens with high public health impact and unmet medical need, development of innovative economic incentives and updated regulatory guidance, R&D of new antibiotics is slowly taking off again.

  4. Taking Immersive VR Leap in Training of Landing Signal Officers.

    PubMed

    Greunke, Larry; Sadagic, Amela

    2016-04-01

    A major training device used to train all Landing Signal Officers (LSOs) for several decades has been the Landing Signal Officer Trainer, Device 2H111. This simulator, located in Oceana, VA, is contained within a two story tall room; it consists of several large screens and a physical rendition of the actual instruments used by LSOs in their operational environment. The young officers who serve in this specialty will typically encounter this system for only a short period of formal instruction (six one-hour long sessions), leaving multiple gaps in training. While experience with 2H111 is extremely valuable for all LSO officers, the amount of time they can spend using this training device is undeniably too short. The need to provide LSOs with an unlimited number of training opportunities unrestricted by location and time, married with recent advancements in commercial off the shelf (COTS) immersive technologies, provided an ideal platform to create a lightweight training solution that would fill those gaps and extend beyond the capabilities currently offered in the 2H111 simulator. This paper details our efforts on task analysis, surveying of user domain, mapping of 2H111 training capabilities to new prototype system to ensure its support of major training objectives of 2H111, design and development of prototype training system, and a feasibility study that included tests of technical system performance and informal testing with trainees at the LSO Schoolhouse. The results achieved in this effort indicate that the time for LSO training to make the leap to immersive VR has decidedly come.

  5. Parabrachial nucleus neuronal responses to off-vertical axis rotation in macaques

    PubMed Central

    McCandless, Cyrus H.; Balaban, Carey D.

    2010-01-01

    The caudal aspect of the parabrachial nucleus (PBN) contains neurons responsive to whole body, periodic rotational stimulation in alert monkeys. This study characterizes the angular and linear motion-sensitive response properties of PBN unit responses during off-vertical axis rotation (OVAR) and position trapezoid stimulation. The OVAR responses displayed a constant firing component which varied from the firing rate at rest. Nearly two-thirds of the units also modulated their discharges with respect to head orientation (re: gravity) during constant velocity OVAR stimulation. The modulated response magnitudes were equal during ipsilateral and contralateral OVARs, indicative of a one-dimensional accelerometer. These response orientations during OVAR divided the units into three spatially tuned populations, with peak modulation responses centered in the ipsilateral ear down, contralateral anterior semicircular canal down, and occiput down orientations. Because the orientation of the OVAR modulation response was opposite in polarity to the orientation of the static tilt component of responses to position trapezoids for the majority of units, the linear acceleration responses were divided into colinear dynamic linear and static tilt components. The orientations of these unit responses formed two distinct population response axes: (1) units with an interaural linear response axis and (2) units with an ipsilateral anterior semicircular canal-contralateral posterior semicircular canal plane linear response axis. The angular rotation sensitivity of these units is in a head-vertical plane that either contains the linear acceleration response axis or is perpendicular to the linear acceleration axis. Hence, these units behave like head-based (‘strap-down’) inertial guidance sensors. Because the PBN contributes to sensory and interoceptive processing, it is suggested that vestibulo-recipient caudal PBN units may detect potentially dangerous anomalies in control of postural

  6. The last deglacial retreat history of the East Antarctic Ice Sheet recorded in sediments from off the Wilkes Land Coast

    NASA Astrophysics Data System (ADS)

    Yokoyama, Y.; Yamane, M.; Miyairi, Y.; Suga, H.; Dunbar, R. B.; Ohkouchi, N.

    2017-12-01

    Timing of past ice sheet retreat of Antarctic continent has been debated with regards to the global sea level changes since the Last Glacial Maximum (LGM) centered at around 20 ka. Exposure dating using cosmogenic radio nuclide (CRN) for glacial deposits have been widely used to reconstruct the last deglacial history though this cannot apply where no-ice free coasts are existed. One such location is the Wilkes Land where the East Antarctic Ice Sheet (EAIS) is situated directory on seafloor. Sediment cores obtained off the Wilkes Land coast successfully retrieved cores during the Intergrated Ocean Drilling Program (IODP) Expedition 318 (Escuita et al., 2011). Major obstacle to obtain reliable chronology for marine cores around Antarctica is sparsity of carbonate materials such as foraminifera. Thus compound-specific radiocarbon analysis (CSRA) has been used and we applied CSRA to the sediments obtained off the Wilkes land coast. The CSRA targeted C16 and C16:1 fatty acid due to their high degradation rate. Hence low concentrations of these compounds are expected. We found major sedimentation occurred since the beginning of Holocene. The result is then compared to the previously reported dates from the land based CRN dates (eg., Mckintosh et al., 2013; Yamane et al., 2011) to discuss the timing of retreat of EAIS.

  7. Case analyses and numerical simulation of soil thermal impacts on land surface energy budget based on an off-line land surface model

    NASA Astrophysics Data System (ADS)

    Guo, W. D.; Sun, S. F.; Qian, Y. F.

    2002-05-01

    The statistical relationship between soil thermal anomaly and short-term climate change is presented based on a typical case study. Furthermore, possible physical mechanisms behind the relationship are revealed through using an off-line land surface model with a reasonable soil thermal forcing at the bottom of the soil layer. In the first experiment, the given heat flux is 5 W m(-2) at the bottom of the soil layer (in depth of 6.3 m) for 3 months, while only a positive ground temperature anomaly of 0.06degreesC can be found compared to the control run. The anomaly, however, could reach 0.65degreesC if the soil thermal conductivity was one order of magnitude larger. It could be even as large as 0.81degreesC assuming the heat flux at bottom is 10 W m(-2). Meanwhile, an increase of about 10 W m(-2) was detected both for heat flux in soil and sensible heat on land surface, which is not neglectable to the short-term climate change. The results show that considerable response in land surface energy budget could be expected when the soil thermal forcing reaches a certain spatial-temporal scale. Therefore, land surface models should not ignore the upward heat flux from the bottom of the soil layer, Moreover, integration for a longer period of time and coupled land-atmosphere model are also necessary for the better understanding of this issues.

  8. Effects of the kinematic viscosity and surface tension on the bubble take-off period in a catalase-hydrogen peroxide system.

    PubMed

    Sasaki, Satoshi; Iida, Yoshinori

    2009-06-01

    The effect of kinematic viscosity and surface tension of the solution was investigated by adding catalase, glucose oxidase, or glucose on the bubble movement in a catalase-hydrogen peroxide system. The kinematic viscosity was measured using a Cannon-Fenske kinematic viscometer. The surface tension of the solution was measured by the Wilhelmy method using a self-made apparatus. The effects of the hole diameter/cell wall thickness, catalase concentration, glucose concentration, and glucose oxidase concentration on the kinematic viscosity, surface tension, and bubble take-off period were investigated. With our system, the effects of the changes in the solution materiality on the bubble take-off period were proven to be very small in comparison to the change in the oxygen-producing rate.

  9. Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. I. Linear acceleration responses during off-vertical axis rotation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Hess, B. J.

    1996-01-01

    1. The dynamic properties of otolith-ocular reflexes elicited by sinusoidal linear acceleration along the three cardinal head axes were studied during off-vertical axis rotations in rhesus monkeys. As the head rotates in space at constant velocity about an off-vertical axis, otolith-ocular reflexes are elicited in response to the sinusoidally varying linear acceleration (gravity) components along the interaural, nasooccipital, or vertical head axis. Because the frequency of these sinusoidal stimuli is proportional to the velocity of rotation, rotation at low and moderately fast speeds allows the study of the mid-and low-frequency dynamics of these otolith-ocular reflexes. 2. Animals were rotated in complete darkness in the yaw, pitch, and roll planes at velocities ranging between 7.4 and 184 degrees/s. Accordingly, otolith-ocular reflexes (manifested as sinusoidal modulations in eye position and/or slow-phase eye velocity) were quantitatively studied for stimulus frequencies ranging between 0.02 and 0.51 Hz. During yaw and roll rotation, torsional, vertical, and horizontal slow-phase eye velocity was sinusoidally modulated as a function of head position. The amplitudes of these responses were symmetric for rotations in opposite directions. In contrast, mainly vertical slow-phase eye velocity was modulated during pitch rotation. This modulation was asymmetric for rotations in opposite direction. 3. Each of these response components in a given rotation plane could be associated with an otolith-ocular response vector whose sensitivity, temporal phase, and spatial orientation were estimated on the basis of the amplitude and phase of sinusoidal modulations during both directions of rotation. Based on this analysis, which was performed either for slow-phase eye velocity alone or for total eye excursion (including both slow and fast eye movements), two distinct response patterns were observed: 1) response vectors with pronounced dynamics and spatial/temporal properties

  10. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take off...

  11. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take off...

  12. 14 CFR 135.385 - Large transport category airplanes: Turbine engine powered: Landing limitations: Destination...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Large transport category airplanes: Turbine....385 Large transport category airplanes: Turbine engine powered: Landing limitations: Destination airports. (a) No person operating a turbine engine powered large transport category airplane may take off...

  13. Three-dimensional landing zone joint capability technology demonstration

    NASA Astrophysics Data System (ADS)

    Savage, James; Goodrich, Shawn; Ott, Carl; Szoboszlay, Zoltan; Perez, Alfonso; Soukup, Joel; Burns, H. N.

    2014-06-01

    The Three-Dimensional Landing Zone (3D-LZ) Joint Capability Technology Demonstration (JCTD) is a 27-month program to develop an integrated LADAR and FLIR capability upgrade for USAF Combat Search and Rescue HH-60G Pave Hawk helicopters through a retrofit of current Raytheon AN/AAQ-29 turret systems. The 3D-LZ JCTD builds upon a history of technology programs using high-resolution, imaging LADAR to address rotorcraft cruise, approach to landing, landing, and take-off in degraded visual environments with emphasis on brownout, cable warning and obstacle avoidance, and avoidance of controlled flight into terrain. This paper summarizes ladar development, flight test milestones, and plans for a final flight test demonstration and Military Utility Assessment in 2014.

  14. Interaction of the elytra and hind wing of a rhinoceros beetle (Trypoxylus dichotomus) during a take-off mode

    NASA Astrophysics Data System (ADS)

    Oh, Seungyoung; Oh, Sehyeong; Choi, Haecheon; Lee, Boogeon; Park, Hyungmin; Kim, Sun-Tae

    2015-11-01

    The elytra are a pair of hardened wings that cover the abdomen of a beetle to protect beetle's hind wings. During the take-off, these elytra open and flap in phase with the hind wings. We investigate the effect of the elytra flapping on beetle's aerodynamic performance. Numerical simulations are performed at Re=10,000 (based on the wingtip mean velocity and mean chord length of the hind wing) using an immersed boundary method. The simulations are focused on a take-off, and the wing kinematics used is directly obtained from the experimental observations using high speed cameras. The simulation result shows three-dimensional vortical structures generated by the hind wing of the beetle and their interaction with the elytra. The presence of elytra has a negative effect on the lift generation by the hind wings, but the lift force on the elytra themselves is negligible. Further discussions on the elytra - hind wing interaction will be provided during the presentation. Supported by UD130070ID.

  15. Feasibility of a responsive, hybrid propulsion augmented, Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit launch system

    NASA Astrophysics Data System (ADS)

    Pelaccio, Dennis G.

    1996-03-01

    A novel, reusable, Vertical-Takeoff-and-Landing, Single-Stage-to-Orbit (VTOL/SSTO) launch system concept, named HYP-SSTO, is presented in this paper. This launch vehicle system concept uses a highly coupled, main high performance liquid oxygen/liquid hydrogen (LOX/LH2) propulsion system, that is used only for launch, with a hybrid auxiliary propulsion system which is used during final orbit insertion, major orbit maneuvering, and landing propulsive burn phases of flight. By using a hybrid propulsion system for major orbit maneuver burns and landing, this launch system concept has many advantages over conventional VTOL/SSTO concepts that use LOX/LH2 propulsion system(s) burns for all phases of flight. Because hybrid propulsion systems are relatively simple and inert by their nature, this concept has the potential to support short turnaround times between launches, be economical to develop, and be competitive in terms of overall system life-cycle cost. This paper provides a technical description of the novel, reusable HYP-SSTO launch system concept. Launch capability performance, as well as major design and operational system attributes, are identified and discussed.

  16. The influence of heel height on vertical ground reaction force during landing tasks in recreationally active and athletic collegiate females.

    PubMed

    Lindenberg, Kelly M; Carcia, Christopher R

    2013-02-01

    To determine if heel height alters vertical ground reaction forces (vGRF) when landing from a forward hop or drop landing. Increased vGRF during landing are theorized to increase ACL injury risk in female athletes. Fifty collegiate females performed two single-limb landing tasks while wearing heel lifts of three different sizes (0, 12 & 24 mm) attached to the bottom of a athletic shoe. Using a force plate, peak vGRF at landing was examined. Repeated measures ANOVAs were used to determine the influence of heel height on the dependent measures. Forward hop task- Peak vGRF (normalized for body mass) with 0 mm, 12 mm, and 24 mm lifts were 2.613±0.498, 2.616±0.497 and 2.495±0.518% BW, respectively. Significant differences were noted between 0 and 24 mm lift (p<.001) and 12 and 24 mm lifts (p=.004), but not between the 0 and 12 mm conditions (p=.927). Jump-landing task- No significant differences were found in peak vGRF (p=.192) between any of the heel lift conditions. The addition of a 24 mm heel lift to the bottom of a sneaker significantly alters peak vGRF upon landing from a unilateral forward hop but not from a jumping maneuver.

  17. Take-Off Time of the First Generation of the Overwintering Small Brown Planthopper, Laodelphax striatellus in the Temperate Zone in East Asia

    PubMed Central

    Sanada-Morimura, Sachiyo; Otuka, Akira; Matsumura, Masaya; Etoh, Tomoki; Zhu, Yeqin; Zhou, Yijun; Zhang, Gufeng

    2015-01-01

    Overseas migration of the small brown planthopper, Laodelphax striatellus (Fallén), occurs during the winter wheat harvest season in East Asia. Knowing the take-off time of emigrating L. striatellus is crucial for predicting such migrations with a simulation technique because winds, carriers of migratory insects, change continuously. Several methods were used in China and Japan from late May to early June 2012 and again in 2013 to identify the precise timing of take-off. These methods included: a tow net trap mounted to a pole at 10 m above the ground, a helicopter-towed net trap, and a canopy trap (which also had video monitoring) set over wheat plants. Laodelphax striatellus emigrated from wheat fields mainly in the early evening, before dusk. The insects also emigrated during the daytime but rarely emigrated at dawn, showing a pattern that is unlike the bimodal emigration at dusk and dawn of two other rice planthoppers, the brown planthopper, Nilaparvata lugens (Stål), and the white-backed planthopper, Sogatella furcifera (Horváth). There was no significant difference in the temporal pattern of take-off behavior between females and males of Japanese L. striatellus populations. PMID:25780936

  18. Spatial distribution and vertical migrations of fish larvae communities off Northwestern Iberia sampled with LHPR and Bongo nets

    NASA Astrophysics Data System (ADS)

    Garrido, Susana; Santos, A. Miguel P.; dos Santos, Antonina; Ré, Pedro

    2009-10-01

    The spatial distribution and diel vertical migration of fish larvae were studied in relation to the environmental conditions off NW Iberia during May 2002. Larvae from 23 families were identified, the most abundant were the Clupeidae, Gobiidae, Callionymidae, Blenniidae, Sparidae and Labridae. Sardina pilchardus was the most abundant species, mean concentrations 1 order of magnitude higher than the other fish larvae species. Larval horizontal distribution was mainly related to upwelling-driven circulation, resulting in an offshore increase of larval abundance while the vertical distribution was closely associated to the Western Iberia Buoyant Plume. Despite this general trend, taxon-specific relationships between the distribution of larvae and environmental variables were observed, and temperature was an important regressor explaining the distribution of most taxa. A comparison between ichthyoplankton samples collected alternatively with the LHPR and Bongo nets resulted in captures of larvae ≈1 order of magnitude higher for the LHPR, probably related to its higher towing speed. The spatial distribution and relative composition of larvae were also different for both nets, although the most frequent/abundant groups were the same. A fixed station sampled for 69-h showed diel vertical migrations performed by the larvae, with the highest larval concentrations occurring at surface layers during the night and most larvae being found in the neuston layer only during that period.

  19. Do Bilateral Vertical Jumps With Reactive Jump Landings Achieve Osteogenic Thresholds With and Without Instruction in Premenopausal Women?

    PubMed

    Clissold, Tracey L; Winwood, Paul W; Cronin, John B; De Souza, Mary Jane

    2018-04-01

    Jumps have been investigated as a stimulus for bone development; however, effects of instruction, jump type, and jump-landing techniques need investigation. This study sought to identify whether ground reaction forces (GRFs) for bilateral vertical jumps (countermovement jumps and drop jumps) with reactive jump-landings (ie, jumping immediately after initial jump-landing), with instruction and with instruction withdrawn, achieve magnitudes and rates of strain previously shown to improve bone mass among premenopausal women. Twenty-one women (Mean ± SD: 43.3 ± 5.9 y; 69.4 ± 9.6 kg; 167 ± 5.5 cm; 27.5 ± 8.7% body fat) performed a testing session 'with instruction' followed by a testing session performed 1 week later with 'instruction withdrawn.' The magnitudes (4.59 to 5.49 body weight [BW]) and rates of strain (263 to 359 BW·s -1 ) for the jump-landings, performed on an AMTI force plate, exceeded previously determined thresholds (>3 BWs and >43 BW·s -1 ). Interestingly, significantly larger peak resultant forces, (↑10%; P = .002) and peak rates of force development (↑20%; P < .001) values (in relation to BW and BW·s -1 , respectively) were observed for the second jump-landing (postreactive jump). Small increases (ES = 0.22-0.42) in all landing forces were observed in the second jump-landing with 'instruction withdrawn.' These jumps represent a unique training stimulus for premenopausal women and achieve osteogenic thresholds thought prerequisite for bone growth.

  20. An experimental simulation study of four crosswind landing gear concepts

    NASA Technical Reports Server (NTRS)

    Stubbs, S. M.; Byrdsong, T. A.; Sleeper, R. K.

    1975-01-01

    An experimental investigation was conducted in order to evaluate several crosswind landing-gear concepts which have a potential application to tricycle-gear-configured, short take-off and landing (STOL) aircraft landing at crab or heading angles up to 30 deg. In this investigation, the landing gears were installed on a dynamic model which had a scaled mass distribution and gear spacing but no aerodynamic similarities when compared with a typical STOL aircraft. The model was operated as a free body with radio-control steering and was launched onto a runway sloped laterally in order to provide a simulated crosswind side force. During the landing rollout, the gear forces and the model trajectory were measured and the various concepts were compared with each other. Within the test limitations, the landing gear system, in which the gears were alined by the pilot and locked in the direction of motion prior to touchdown, gave the smoothest runout behavior with the vehicle maintaining its crab angle throughout the landing runout.

  1. Force balance in the take-off of a pierid butterfly: relative importance and timing of leg impulsion and aerodynamic forces.

    PubMed

    Bimbard, Gaëlle; Kolomenskiy, Dmitry; Bouteleux, Olivier; Casas, Jérôme; Godoy-Diana, Ramiro

    2013-09-15

    Up to now, the take-off stage has remained an elusive phase of insect flight that was relatively poorly explored compared with other maneuvers. An overall assessment of the different mechanisms involved in force production during take-off has never been explored. Focusing on the first downstroke, we have addressed this problem from a force balance perspective in butterflies taking off from the ground. In order to determine whether the sole aerodynamic wing force could explain the observed motion of the insect, we have firstly compared a simple analytical model of the wing force with the acceleration of the insect's center of mass estimated from video tracking of the wing and body motions. Secondly, wing kinematics were also used for numerical simulations of the aerodynamic flow field. Similar wing aerodynamic forces were obtained by the two methods. However, neither are sufficient, nor is the inclusion of the ground effect, to predict faithfully the body acceleration. We have to resort to the leg forces to obtain a model that best fits the data. We show that the median and hind legs display an active extension responsible for the initiation of the upward motion of the insect's body, occurring before the onset of the wing downstroke. We estimate that legs generate, at various times, an upward force that can be much larger than all other forces applied to the insect's body. The relative timing of leg and wing forces explains the large variability of trajectories observed during the maneuvers.

  2. Phase-linking and the perceived motion during off-vertical axis rotation.

    PubMed

    Holly, Jan E; Wood, Scott J; McCollum, Gin

    2010-01-01

    Human off-vertical axis rotation (OVAR) in the dark typically produces perceived motion about a cone, the amplitude of which changes as a function of frequency. This perception is commonly attributed to the fact that both the OVAR and the conical motion have a gravity vector that rotates about the subject. Little-known, however, is that this rotating-gravity explanation for perceived conical motion is inconsistent with basic observations about self-motion perception: (a) that the perceived vertical moves toward alignment with the gravito-inertial acceleration (GIA) and (b) that perceived translation arises from perceived linear acceleration, as derived from the portion of the GIA not associated with gravity. Mathematically proved in this article is the fact that during OVAR these properties imply mismatched phase of perceived tilt and translation, in contrast to the common perception of matched phases which correspond to conical motion with pivot at the bottom. This result demonstrates that an additional perceptual rule is required to explain perception in OVAR. This study investigates, both analytically and computationally, the phase relationship between tilt and translation at different stimulus rates-slow (45 degrees /s) and fast (180 degrees /s), and the three-dimensional shape of predicted perceived motion, under different sets of hypotheses about self-motion perception. We propose that for human motion perception, there is a phase-linking of tilt and translation movements to construct a perception of one's overall motion path. Alternative hypotheses to achieve the phase match were tested with three-dimensional computational models, comparing the output with published experimental reports. The best fit with experimental data was the hypothesis that the phase of perceived translation was linked to perceived tilt, while the perceived tilt was determined by the GIA. This hypothesis successfully predicted the bottom-pivot cone commonly reported and a reduced sense

  3. Phase-linking and the perceived motion during off-vertical axis rotation

    PubMed Central

    Wood, Scott J.; McCollum, Gin

    2010-01-01

    Human off-vertical axis rotation (OVAR) in the dark typically produces perceived motion about a cone, the amplitude of which changes as a function of frequency. This perception is commonly attributed to the fact that both the OVAR and the conical motion have a gravity vector that rotates about the subject. Little-known, however, is that this rotating-gravity explanation for perceived conical motion is inconsistent with basic observations about self-motion perception: (a) that the perceived vertical moves toward alignment with the gravito-inertial acceleration (GIA) and (b) that perceived translation arises from perceived linear acceleration, as derived from the portion of the GIA not associated with gravity. Mathematically proved in this article is the fact that during OVAR these properties imply mismatched phase of perceived tilt and translation, in contrast to the common perception of matched phases which correspond to conical motion with pivot at the bottom. This result demonstrates that an additional perceptual rule is required to explain perception in OVAR. This study investigates, both analytically and computationally, the phase relationship between tilt and translation at different stimulus rates—slow (45°/s) and fast (180°/s), and the three-dimensional shape of predicted perceived motion, under different sets of hypotheses about self-motion perception. We propose that for human motion perception, there is a phase-linking of tilt and translation movements to construct a perception of one’s overall motion path. Alternative hypotheses to achieve the phase match were tested with three-dimensional computational models, comparing the output with published experimental reports. The best fit with experimental data was the hypothesis that the phase of perceived translation was linked to perceived tilt, while the perceived tilt was determined by the GIA. This hypothesis successfully predicted the bottom-pivot cone commonly reported and a reduced sense of tilt

  4. Do the kinematics of a baulked take-off in springboard diving differ from those of a completed dive.

    PubMed

    Barris, Sian; Farrow, Damian; Davids, Keith

    2013-01-01

    Consistency and invariance in movements are traditionally viewed as essential features of skill acquisition and elite sports performance. This emphasis on the stabilization of action has resulted in important processes of adaptation in movement coordination during performance being overlooked in investigations of elite sport performance. Here we investigate whether differences exist between the movement kinematics displayed by five, elite springboard divers (age 17 ± 2.4 years) in the preparation phases of baulked and completed take-offs. The two-dimensional kinematic characteristics of the reverse somersault take-off phases (approach and hurdle) were recorded during normal training sessions and used for intra-individual analysis. All participants displayed observable differences in movement patterns at key events during the approach phase; however, the presence of similar global topological characteristics suggested that, overall, participants did not perform distinctly different movement patterns during completed and baulked dives. These findings provide a powerful rationale for coaches to consider assessing functional variability or adaptability of motor behaviour as a key criterion of successful performance in sports such as diving.

  5. Controller partitioning for integrated flight/propulsion control implementation

    NASA Technical Reports Server (NTRS)

    Garg, Sanjay

    1993-01-01

    The notion of partitioning a centralized controller into a decentralized, hierarchical structure suitable for integrated flight/propulsion control (IFPC) implementation is discussed. A systematic procedure is developed for determining partitioned airframe and engine subsystem controllers (subcontrollers), with the desired interconnection structure, that approximate the closed-loop performance and robustness characteristics of a given centralized controller. The procedure is demonstrated by application to IFPC design for a Short Take-Off and Vertical Landing (STOVL) aircraft in the landing approach to hover transition flight phase.

  6. Partitioning of centralized integrated flight/propulsion control design for decentralized implementation

    NASA Technical Reports Server (NTRS)

    Garg, Sanjay

    1993-01-01

    The notion of partitioning a centralized controller into a decentralized, hierarchical structure suitable for integrated flight/propulsion control (IFPC) implementation is discussed. A systematic procedure is developed for determining partitioned airframe and engine subsystem controllers (subcontrollers), with the desired interconnection structure, that approximate the closed-loop performance and robustness characteristics of a given centralized controller. The procedure is demonstrated by application to IFPC design for a short take-off and vertical landing (STOVL) aircraft in the landing-approach-to-hover-transition flight phase.

  7. Impact differences in ground reaction force and center of mass between the first and second landing phases of a drop vertical jump and their implications for injury risk assessment.

    PubMed

    Bates, Nathaniel A; Ford, Kevin R; Myer, Gregory D; Hewett, Timothy E

    2013-04-26

    The drop vertical jump (DVJ) task is commonly used to assess biomechanical performance measures that are associated with ACL injury risk in athletes. Previous investigations have solely assessed the first landing phase. We examined the first and second landings of a DVJ for differences in the magnitude of vertical ground reaction force (vGRF) and position of center of mass (CoM). A cohort of 239 adolescent female basketball athletes completed a series of DVJ tasks from an initial box height of 31 cm. Dual force platforms and a three dimensional motion capture system recorded force and positional data for each trial. There was no difference in peak vGRF between landings (p=0.445), but side-to-side differences increased from the first to second landing (p=0.007). Participants demonstrated a lower minimum CoM during stance in the first landing than the second landing (p<0.001). The results have important implications for the future assessment of ACL injury risk behaviors in adolescent female athletes. Greater side-to-side asymmetry in vGRF and higher CoM during impact indicate the second landing of a DVJ may exhibit greater perturbation and better represent in-game mechanics associated with ACL injury risk. Copyright © 2013 Elsevier Ltd. All rights reserved.

  8. Land-use change in oil palm dominated tropical landscapes-An agent-based model to explore ecological and socio-economic trade-offs.

    PubMed

    Dislich, Claudia; Hettig, Elisabeth; Salecker, Jan; Heinonen, Johannes; Lay, Jann; Meyer, Katrin M; Wiegand, Kerstin; Tarigan, Suria

    2018-01-01

    Land-use changes have dramatically transformed tropical landscapes. We describe an ecological-economic land-use change model as an integrated, exploratory tool used to analyze how tropical land-use change affects ecological and socio-economic functions. The model analysis seeks to determine what kind of landscape mosaic can improve the ensemble of ecosystem functioning, biodiversity, and economic benefit based on the synergies and trade-offs that we have to account for. More specifically, (1) how do specific ecosystem functions, such as carbon storage, and economic functions, such as household consumption, relate to each other? (2) How do external factors, such as the output prices of crops, affect these relationships? (3) How do these relationships change when production inefficiency differs between smallholder farmers and learning is incorporated? We initialize the ecological-economic model with artificially generated land-use maps parameterized to our study region. The economic sub-model simulates smallholder land-use management decisions based on a profit maximization assumption. Each household determines factor inputs for all household fields and decides on land-use change based on available wealth. The ecological sub-model includes a simple account of carbon sequestration in above-ground and below-ground vegetation. We demonstrate model capabilities with results on household consumption and carbon sequestration from different output price and farming efficiency scenarios. The overall results reveal complex interactions between the economic and ecological spheres. For instance, model scenarios with heterogeneous crop-specific household productivity reveal a comparatively high inertia of land-use change. Our model analysis even shows such an increased temporal stability in landscape composition and carbon stocks of the agricultural area under dynamic price trends. These findings underline the utility of ecological-economic models, such as ours, to act as

  9. Structural Sizing of a Horizontal Take-Off Launch Vehicle with an Air Collection and Enrichment System

    NASA Technical Reports Server (NTRS)

    McCurdy, David R.; Roche, Joseph M.

    2004-01-01

    In support of NASA's Next Generation Launch Technology (NGLT) program, the Andrews Gryphon booster was studied. The Andrews Gryphon concept is a horizontal lift-off, two-stage-to-orbit, reusable launch vehicle that uses an air collection and enrichment system (ACES). The purpose of the ACES is to collect atmospheric oxygen during a subsonic flight loiter phase and cool it to cryogenic temperature, ultimately resulting in a reduced initial take-off weight To study the performance and size of an air-collection based booster, an initial airplane like shape was established as a baseline and modeled in a vehicle sizing code. The code, SIZER, contains a general series of volume, surface area, and fuel fraction relationships that tie engine and ACES performance with propellant requirements and volumetric constraints in order to establish vehicle closure for the given mission. A key element of system level weight optimization is the use of the SIZER program that provides rapid convergence and a great deal of flexibility for different tank architectures and material suites in order to study their impact on gross lift-off weight. This paper discusses important elements of the sizing code architecture followed by highlights of the baseline booster study.

  10. Coastline shifts and probable ship landing site submerged off ancient Locri-Epizefiri, southern Italy

    USGS Publications Warehouse

    Tennent, J.M.; Stanley, J.-D.; Hart, P.E.; Bernasconi, M.P.

    2009-01-01

    A geophysical survey provides new information on marine features located seaward of Locri-Epizefiri (Locri), an ancient Greek settlement on the Ionian coastal margin in southern Italy. The study supplements previous work by archaeologists who long searched for the site's harbor and recently identified what was once a marine basin that is now on land next to the city walls of Locri. Profiles obtained offshore, between the present coast and outer shelf, made with a high-resolution, seismic subbottom-profiling system, record spatial and temporal variations of buried Holocene deposits. Two of these submerged features are part of a probable now-submerged ship landing facility. The offshore features can be linked to coastline displacements that occurred off Locri: a sea-to-land shift before Greek settlement, followed by a shoreline reversal from the archaeological site back to sea, and more recently, a return landward. The seaward directed coastal shift that occurred after Locri's occupation by Greeks was likely caused by land uplift near the coastal margin and tectonic seaward shift of the coast, as documented along this geologically active sector of the Calabrian Arc. The seismic survey records an angular, hook-shaped, low rise that extends from the present shore and is now buried on the inner shelf. The rise, enclosing a core lens of poorly stratified to transparent acoustic layers, bounds a broad, low-elevation zone positioned immediately seaward of the shoreline. Close proximity of the raised feature to the low-elevation area suggests it may have been a fabricated structure that functioned as a wave-break for a ship-landing site. The study indicates that the basin extended offshore as a function of the coastline's seaward migration during and/or after Greek occupation of Locri.

  11. A vertically integrated snow/ice model over land/sea for climate models. I - Development. II - Impact on orbital change experiments

    NASA Technical Reports Server (NTRS)

    Neeman, Binyamin U.; Ohring, George; Joseph, Joachim H.

    1988-01-01

    A vertically integrated formulation (VIF) model for sea ice/snow and land snow is discussed which can simulate the nonlinear effects of heat storage and transfer through the layers of snow and ice. The VIF demonstates the accuracy of the multilayer formulation, while benefitting from the computational flexibility of linear formulations. In the second part, the model is implemented in a seasonal dynamic zonally averaged climate model. It is found that, in response to a change between extreme high and low summer insolation orbits, the winter orbital change dominates over the opposite summer change for sea ice. For snow over land the shorter but more pronounced summer orbital change is shown to dominate.

  12. The effects of klapskate hinge position on push-off performance: a simulation study.

    PubMed

    Houdijk, Han; Bobbert, Maarten F; De Koning, Jos J; De Groot, Gert

    2003-12-01

    The introduction of the klapskate in speed skating confronts skaters with the question of how to adjust the position of the hinge in order to maximize performance. The purpose of this study was to reveal the constraint that klapskate hinge position imposes on push-off performance in speed skating. For this purpose, a model of the musculoskeletal system was designed to simulate a simplified, two-dimensional skating push off. To capture the essence of a skating push off, this model performed a one-leg vertical jump, from a frictionless surface, while keeping its trunk horizontally. In this model, klapskate hinge position was varied by varying the length of the foot segment between 115 and 300 mm. With each foot length, an optimal control solution was found that resulted in the maximal amount of vertical kinetic and potential energy of the body's center of mass at take off (Weff). Foot length was shown to considerably affect push-off performance. Maximal Weff was obtained with a foot length of 185 mm and decreased by approximately 25% at either foot length of 115 mm and 300 mm. The reason for this decrease was that foot length affected the onset and control of foot rotation. This resulted in a distortion of the pattern of leg segment rotations and affected muscle work (Wmus) and the efficacy ratio (Weff/Wmus) of the entire leg system. Despite its simplicity, the model very well described and explained the effects of klapskate hinge position on push off performance that have been observed in speed-skating experiments. The simplicity of the model, however, does not allow quantitative analyses of optimal klapskate hinge position for speed-skating practice.

  13. Flight Tests of a 0.13-Scale Model of the Convair XFY-1 Vertically Rising Airplane with the Lower Vertical Tail Removed, TED No.DE 368

    NASA Technical Reports Server (NTRS)

    Lovell, Powell M., Jr.

    1954-01-01

    An experimental investigation has been conducted to determine the dynamic stability and control characteristics in hovering and transition flight of a 0.13-scale flying model of the Convair XFY-1 vertically rising airplane with the lower vertical tail removed. The purpose of the tests was to obtain a general indication of the behavior of a vertically rising airplane of the same general type as the XFY-1 but without a lower vertical tail in order to simplify power-off belly landings in an emergency. The model was flown satisfactorily in hovering flight and in the transition from hovering to normal unstalled forward flight (angle of attack approximately 30deg). From an angle of attack of about 30 down to the lowest angle of attack covered in the flight tests (approximately 15deg) the model became progressively more difficult to control. These control difficulties were attributed partly to a lightly damped Dutch roll oscillation and partly to the fact that the control deflections required for hovering and transition flight were too great for smooth flight at high speeds. In the low-angle-of-attack range not covered in the flight tests, force tests have indicated very low static directional stability which would probably result in poor flight characteristics. It appears, therefore, that the attainment of satisfactory directional stability, at angles of attack less than 10deg, rather than in the hovering and transition ranges of flight is the critical factor in the design of the vertical tail for such a configuration.

  14. Transcutaneous spinal direct current stimulation induces lasting fatigue resistance and enhances explosive vertical jump performance

    PubMed Central

    Tate, Rothwelle J.; Conway, Bernard A.

    2017-01-01

    Transcutaneous spinal direct current stimulation (tsDCS) is a non-invasive neuromodulatory intervention that has been shown to modify excitability in spinal and supraspinal circuits in animals and humans. Our objective in this study was to explore the functional neuromodulatory potential of tsDCS by examining its immediate and lasting effects over the repeated performance of a whole body maximal exercise in healthy volunteers. Using a double-blind, randomized, crossover, sham-controlled design we investigated the effects of 15 min of anodal tsDCS on repeated vertical countermovement jump (VCJ) performance at 0, 20, 60, and 180 minutes post-stimulation. Measurements of peak and take-off velocity, vertical displacement, peak power and work done during countermovement and push-off VCJ phases were derived from changes in vertical ground reaction force (12 performance parameters) in 12 healthy participants. The magnitude and direction of change in VCJ performance from pre- to post-stimulation differed significantly between sham and active tsDCS for 7 of the 12 VCJ performance measures (P < 0.05). These differences comprised of a post-sham fatigue in VCJ displacement/work done, peak to peak power and take-off velocity, and a resilience to this fatigue effect post-active tsDCS. In addition there was also an enhancement of countermovement performance and total work done (P < 0.05). These changes did not vary across repeated VCJ performances over time post-tsDCS (P > 0.05). Our original findings demonstrate that one single session of anodal tsDCS in healthy subjects can prevent fatigue and maintain or enhance different aspects of whole body explosive motor power over repeated sets of VCJs performed over a period of three hours. The observed effects are discussed in relation to alterations in central fatigue mechanisms, muscle contraction mode during jump execution and changes in spinal cord excitability. These findings have important implications for power endurance sport

  15. Time changes in radiocesium wash-off from various land uses after the Fukushima Daiichi NPP accident

    NASA Astrophysics Data System (ADS)

    Onda, Yuichi; Kato, Hiroaki; Yoshimura, Kazuya; Tsujimura, Maki; Wakiyama, Yoshifumi; Taniguchi, Keisuke; Sakaguchi, Aya; Yamamoto, Masayoshi

    2014-05-01

    A number of studies have been conducted to monitor and model the time series change of radiocesium transfer through aquatic systems after significant fallout, especially from the Chernobyl disaster. However, no data is available for the temporal changes of radiocesium concentration in environmental materials such as soil and water after the Fukushima Daiichi nuclear power plant accident. Our research team has been monitoring the environmental consequences of radioactive contamination just after the Fukushima Daiichi NPP accident in Yamakiya-district, Kawamata town, Fukushima prefecture. Research items are listed below. 1. Radiocesium wash-off from the runoff-erosion plot under different land use. 2. Measurement of radiocesium transfer in forest environment, in association with hydrological pathways such as throughfall and overlandflow on hillslope. 3. Monitoring on radiocesium concentration in soil water, ground water, and spring water. 4. Monitoring of dissolved and particulate radiocesium concentration in river water, and stream water from the forested catchment. 5.Measurement of radiocesium content in drain water and suspended sediment from paddy field. Our monitoring result demonstrated that the Cs-137 concentration in eroded sediment from the runoff-erosion plot has been almost constant for the past 3 years, however the Cs-137 concentration of suspended sediment from the forested catchment showed slight decrease through time. On the other hand, the suspended sediment from paddy field and those in river water from large catchments exhibited rapid decrease in Cs-137 concentration with time. The decreasing trend of Cs-137 concentration were fitted by the two-component exponential model, differences in decreasing rate of the model were compared and discussed among various land uses and catchment scales. Such analysis can provide important insights into the future prediction of the radiocesium wash-off from catchments with different land uses.

  16. Estimation of surface-level PM concentration from satellite observation taking into account the aerosol vertical profiles and hygroscopicity.

    PubMed

    Kim, Kwanchul; Lee, Kwon H; Kim, Ji I; Noh, Youngmin; Shin, Dong H; Shin, Sung K; Lee, Dasom; Kim, Jhoon; Kim, Young J; Song, Chul H

    2016-01-01

    Surface-level PM10 distribution was estimated from the satellite aerosol optical depth (AOD) products, taking the account of vertical profiles and hygroscopicity of aerosols over Jeju, Korea during March 2008 and October 2009. In this study, MODIS AOD data from the Terra and Aqua satellites were corrected with aerosol extinction profiles and relative humidity data. PBLH (Planetary Boundary Layer Height) was determined from MPLNET lidar-derived aerosol extinction coefficient profiles. Through statistical analysis, better agreement in correlation (R = 0.82) between the hourly PM10 concentration and hourly average Sunphotometer AOD was the obtained when vertical fraction method (VFM) considering Haze Layer Height (HLH) and hygroscopic growth factor f(RH) was used. The validity of the derived relationship between satellite AOD and surface PM10 concentration clearly demonstrates that satellite AOD data can be utilized for remote sensing of spatial distribution of regional PM10 concentration. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  17. The biomechanics of one-footed vertical jump performance in unilateral trans-tibial amputees.

    PubMed

    Strike, S C; Diss, C

    2005-04-01

    This study investigated vertical jumps from single support for two trans-tibial amputees from a standing position. The mechanisms used to achieve flight and the compensatory mechanisms used in the production of force in the absence of plantarflexors are detailed. Two participants completed countermovement maximum vertical jumps from the prosthetic and the sound limbs. The jumps were recorded by a 7-camera 512 VICON motion analysis system integrated with a Kistler forceplate. Flight height was 5 cm jumping from the prosthetic side and 18-19 cm from the sound side. The countermovement was shallower and its duration was less on the prosthetic side compared to the sound side. The reduced and passive range of motion at the prosthesis resulted in an asymmetrical countermovement for both participants with the knee and ankle joints most affected. The duration of the push-off phase was not consistently affected. At take-off the joints on the sound side reached close to full extension while on the prosthetic side they remained more flexed. Joint extension velocity in the push-off phase was similar for both participants on the sound side, though the timing for participant 2 illustrated earlier peaks. The pattern of joint extension velocity was not a smooth proximal to distal sequence on the prosthetic side. The magnitude and timing of the inter-segment extensor moments were asymmetrical for both subjects. The power pattern was asymmetrical in both the countermovement and push-off phases; the lack of power generation at the ankle affected that produced at the remaining joints.

  18. Steerable vertical to horizontal energy transducer for mobile robots

    DOEpatents

    Spletzer, Barry L.; Fischer, Gary J.; Feddema, John T.

    2001-01-01

    The present invention provides a steerable vertical to horizontal energy transducer for mobile robots that less complex and requires less power than two degree of freedom tilt mechanisms. The present invention comprises an end effector that, when mounted with a hopping actuator, translates along axis (typically vertical) actuation into combined vertical and horizontal motion. The end effector, or foot, mounts with an end of the actuator that moves toward the support surface (typically a floor or the earth). The foot is shaped so that the first contact with the support surface is off the axis of the actuator. Off-axis contact with the support surface generates an on-axis force (typically resulting in vertical motion) and a moment orthogonal to the axis. The moment initiates a horizontal tumbling motion, and tilts the actuator so that its axis is oriented with a horizontal component and continued actuation generates both vertical and horizontal force.

  19. In-Situ Resource Utilization: Laying the Foundation for "Living off the Land"

    NASA Technical Reports Server (NTRS)

    Kaplan, D. I.

    2000-01-01

    The technology to manufacture rocket propellants, breathing and life-support gases, fuel cell reagents, and other consumables on Mars using indigenous Martian resources as feedstock in the production process is known as In-Situ Resource Utilization (ISRU). Several studies of the long-term, committed exploration of Mars by humans show that ISRU is essential ... an enabling technology. The recognized value of ISRU to human exploration is reflected in the NASA Strategic Plan. In the description of the "Strategies and Outcomes" of the Human Exploration and Development of Space (HEDS) Enterprise, the NASA Strategic Plan states: The [HEDS] Enterprise relies on the robotic missions of the Space Science Enterprise to provide extensive knowledge of the geology, environment, and resources of planetary bodies. The Space Science Enterprise missions will also demonstrate the feasibility of utilizing local resources to "live off the land."

  20. The Study of Attachment between Distribution Pattern of Land Price and Apartments Price (Case Study: Vertical Housing Development in Administration City of South Jakarta)

    NASA Astrophysics Data System (ADS)

    Sugiyantoro; Christian, B.; Arianto, R.

    2018-05-01

    Land and it’s utilization on housing development undoubtedly have become an essential issue in various studies. The comprehension on each locations of the case has allowed several important studies of particular patterns related to the capacity of land and housing market. Especially Jakarta as the most promising area for property business, also has the highest lands and apartments price in Indonesia. Land and apartment are considered as the most unique commodities, highly profitable. But since 2014, there has been lots of warnings about possibility of apartments oversupply; stagnation of apartment sales also has been indicated in locations at the edge of this city, which will enable the demand’s transition from landed house to apartment, as form of vertical housing. Based on fundamental theories of land and apartment pricing, the research presumes that apartment development is considered as an effort of land intensifications, to trigger the enhancement of land prices in particular locations. Therefore, this research means to comprehend the correlation of distribution pattern of lands price with apartments price. The location’s selection is based on expansion of the urban development of Jakarta Metropolitan Area to southern region which has become a general tendency.

  1. Effect of UV-Blocking Plastic Films on Take-Off and Host Plant Finding Ability of Diaphorina citri (Hemiptera: Liviidae).

    PubMed

    Miranda, M P; Dos Santos, F L; Felippe, M R; Moreno, A; Fereres, A

    2015-02-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus worldwide due to its ability to transmit the bacteria associated with huanglongbing. Vision, behavior, and performance of insect pests can be manipulated by using ultraviolet (UV)-blocking materials. Thus, the aim of our study was to evaluate how UV-blocking plastic films may affect the take-off and host plant finding ability of D. citri. To assess the effect of a UV-deficient environment on take-off, adult psyllids were released from a vial inside a screenhouse covered by a UV-blocking or standard (control) film and the number of insects remaining on each vial under each treatment was counted at different time intervals. Moreover, to assess the ability of D. citri to find citrus plants under a UV-deficient environment, two independent no-choice host plant finding assays with different plant arrangements were conducted. In each treatment, the number of psyllids per plant at different time intervals was counted. Both D. citri take-off and host plant finding ability was clearly disrupted under a UV-deficient environment. The number of psyllids remaining in the vials was significantly higher under UV-blocking than standard film in all periods recorded. Furthermore, psyllids were present in significantly higher number on citrus plants under standard film than under UV-blocking film in all of the periods assessed and experiments conducted. Our results showed that UV-blocking materials could become a valuable strategy for integrated management of D. citri and huanglongbing in citrus grown in enclosed environments. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Some Studies in Large-Scale Surface Fluxes and Vertical Motions Associated with Land falling Hurricane Katrina over the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Reddy, S. R.

    2010-12-01

    We investigated the possible relationship between the large- scale heat fluxes and intensity change associated with the landfall of Hurricane Katrina. After reaching the category 5 intensity on August 28th , 2005 over the central Gulf of Mexico, Katrina weekend to category 3 before making landfall (August 29th , 2005) on the Louisiana coast with the maximum sustained winds of over 110 knots. We also examined the vertical motions associated with the intensity change of the hurricane. The data on Convective Available Potential Energy (CAPE), sea level pressure and wind speed were obtained from the Atmospheric Soundings, and NOAA National Hurricane Center (NHC), respectively for the period August 24 to September 3, 2005. We developed an empirical model and a C++ program to calculate surface potential temperatures and heat fluxes using the above data. We also computed vertical motions using CAPE values. The study showed that the large-scale heat fluxes reached maximum (7960W/m2) with the central pressure 905mb. The Convective Available Potential Energy and the vertical motions peaked 3-5 days before landfall. The large atmospheric vertical motions associated with the land falling hurricane Katrina produced severe weather including thunderstorms and tornadoes.

  3. Vertical III-nitride thin-film power diode

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

    Wierer, Jr., Jonathan; Fischer, Arthur J.; Allerman, Andrew A.

    2017-03-14

    A vertical III-nitride thin-film power diode can hold off high voltages (kV's) when operated under reverse bias. The III-nitride device layers can be grown on a wider bandgap template layer and growth substrate, which can be removed by laser lift-off of the epitaxial device layers grown thereon.

  4. Integration of Rotor Aerodynamic Optimization with the Conceptual Design of a Large Civil Tiltrotor

    DTIC Science & Technology

    2010-01-01

    Rotor MCP Maximum Continuous Power MRP Maximum Rated Power (take-off power) NDARC NASA Design and Analysis of Rotorcraft OEI One Engine Inoperative...OGE Out of Ground Effect SFC Specific Fuel Consumption SNI Simultaneous Non-Interfering approach STOL Short Takeoff and Landing VTOL Vertical...that are assembled into a complete aircraft model. NDARC is designed for high computational efficiency. Performance is calculated with physics- based

  5. Simulation of Thrust-Vectored Aircraft Maneuvers on a Human Centrifuge: Model Validation and Design for the Dynamic Environment Simulator

    DTIC Science & Technology

    1998-09-01

    reviewed and is approved for publication. FOR THE DIRECTOR ROGER L. STORK , Colonel, USAF, BSC Chief, Biodynamics and Protection Division Air Force Research...possible disorienting stimuli. Short radius yaw rotational movements that occur in helicopter flight and vertical take off and landing (VTOL) fixed wing ... wing flight. Aeronautical terms and thought has evolved. Tactical concepts, once thought inviolate, are changing. New terms are emerging and the very

  6. Assessment of Urban Aerial Taxi with Cryogenic Components Under Design Environment for Novel Vertical Lift Vehicles (DELIVER)

    NASA Technical Reports Server (NTRS)

    Snyder, Christopher

    2017-01-01

    Assessing the potential to bring 100 years of aeronautics knowledge to the entrepreneurs desktop to enable a design environment for emerging vertical lift vehicles is one goal for the NASA's Design Environment for Novel Vertical Lift Vehicles (DELIVER). As part of this effort, a system study was performed using a notional, urban aerial taxi system to better understand vehicle requirements along with the tools and methods capability to assess these vehicles and their subsystems using cryogenic cooled components. The baseline was a vertical take-off and landing (VTOL) aircraft, with all-electric propulsion system assuming 15 year technology performance levels and its capability limited to a pilot with one or two people and cargo. Hydrocarbon-fueled hybrid concepts were developed to improve mission capabilities. The hybrid systems resulted in significant improvements in maximum range and number of on demand mobility (ODM) missions that could be completed before refuel or recharge. An important consideration was thermal management, including the choice for air-cooled or cryogenic cooling using liquid natural gas (LNG) fuel. Cryogenic cooling for critical components can have important implications on component performance and size. Thermal loads were also estimated, subsequent effort will be required to verify feasibility for cooling airflow and packaging. LNG cryogenic cooling of selected components further improved vehicle range and reduced thermal loads, but the same concerns for airflow and packaging still need to be addressed. The use of the NASA Design and Analysis of Rotorcraft (NDARC) tool for vehicle sizing and mission analysis appears to be capable of supporting analyses for present and future types of vehicles, missions, propulsion, and energy sources. Further efforts are required to develop verified models for these new types of propulsion and energy sources in the size and use envisioned for these emerging vehicle and mission classes.

  7. Assessment of Urban Aerial Taxi with Cryogenic Components under Design Environment for Novel Vertical Lift Vehicles (DELIVER)

    NASA Technical Reports Server (NTRS)

    Snyder, Christopher A.

    2017-01-01

    Assessing the potential to bring 100 years of aeronautics knowledge to the entrepreneurs desktop to enable a design environment for emerging vertical lift vehicles is one goal for the NASAs Design Environment for Novel Vertical Lift Vehicles (DELIVER). As part of this effort, a system study was performed using a notional, urban aerial taxi system to better understand vehicle requirements along with the tools and methods capability to assess these vehicles and their subsystems using cryogenic cooled components. The baseline was a vertical take-off and landing (VTOL) aircraft, with all-electric propulsion system assuming 15 year technology performance levels and its capability limited to a pilot with one or two people and cargo. Hydrocarbon-fueled hybrid concepts were developed to improve mission capabilities. The hybrid systems resulted in significant improvements in maximum range and number of on demand mobility (ODM) missions that could be completed before refuel or recharge. An important consideration was thermal management, including the choice for air-cooled or cryogenic cooling using liquid natural gas (LNG) fuel. Cryogenic cooling for critical components can have important implications on component performance and size. Thermal loads were also estimated, subsequent effort will be required to verify feasibility for cooling airflow and packaging. LNG cryogenic cooling of selected components further improved vehicle range and reduced thermal loads, but the same concerns for airflow and packaging still need to be addressed. The use of the NASA Design and Analysis of Rotorcraft (NDARC) tool for vehicle sizing and mission analysis appears to be capable of supporting analyses for present and future types of vehicles, missions, propulsion, and energy sources. Further efforts are required to develop verified models for these new types of propulsion and energy sources in the size and use envisioned for these emerging vehicle and mission classes.

  8. Land-use change in oil palm dominated tropical landscapes—An agent-based model to explore ecological and socio-economic trade-offs

    PubMed Central

    Dislich, Claudia; Hettig, Elisabeth; Heinonen, Johannes; Lay, Jann; Meyer, Katrin M.; Wiegand, Kerstin; Tarigan, Suria

    2018-01-01

    Land-use changes have dramatically transformed tropical landscapes. We describe an ecological-economic land-use change model as an integrated, exploratory tool used to analyze how tropical land-use change affects ecological and socio-economic functions. The model analysis seeks to determine what kind of landscape mosaic can improve the ensemble of ecosystem functioning, biodiversity, and economic benefit based on the synergies and trade-offs that we have to account for. More specifically, (1) how do specific ecosystem functions, such as carbon storage, and economic functions, such as household consumption, relate to each other? (2) How do external factors, such as the output prices of crops, affect these relationships? (3) How do these relationships change when production inefficiency differs between smallholder farmers and learning is incorporated? We initialize the ecological-economic model with artificially generated land-use maps parameterized to our study region. The economic sub-model simulates smallholder land-use management decisions based on a profit maximization assumption. Each household determines factor inputs for all household fields and decides on land-use change based on available wealth. The ecological sub-model includes a simple account of carbon sequestration in above-ground and below-ground vegetation. We demonstrate model capabilities with results on household consumption and carbon sequestration from different output price and farming efficiency scenarios. The overall results reveal complex interactions between the economic and ecological spheres. For instance, model scenarios with heterogeneous crop-specific household productivity reveal a comparatively high inertia of land-use change. Our model analysis even shows such an increased temporal stability in landscape composition and carbon stocks of the agricultural area under dynamic price trends. These findings underline the utility of ecological-economic models, such as ours, to act as

  9. Land motion estimates from GPS at tide gauges: a geophysical evaluation

    NASA Astrophysics Data System (ADS)

    Bouin, M. N.; Wöppelmann, G.

    2010-01-01

    Space geodesy applications have mainly been limited to horizontal deformations due to a number of restrictions on the vertical component accuracy. Monitoring vertical land motion is nonetheless of crucial interest in observations of long-term sea level change or postglacial rebound measurements. Here, we present a global vertical velocity field obtained with more than 200 permanent GPS stations, most of them colocated with tide gauges (TGs). We used a state of the art, homogeneous processing strategy to ensure that the reference frame was stable throughout the observation period of almost 10 yr. We associate realistic uncertainties to our vertical rates, taking into account the time-correlation noise in the time-series. The results are compared with two independent geophysical vertical velocity fields: (1) vertical velocity estimates using long-term TG records and (2) postglacial model predictions from the ICE-5G (VM2) adjustment. The quantitative agreement of the GPS vertical velocities with the `internal estimates' of vertical displacements using the TG record is very good, with a mean difference of -0.13 +/- 1.64 mm yr-1 on more than 100 sites. For 84 per cent of the GPS stations considered, the vertical velocity is confirmed by the TG estimate to within 2 mm yr-1. The overall agreement with the glacial isostatic adjustment (GIA) model is good, with discrepancy patterns related either to a local misfit of the model or to active tectonics. For 72 per cent of the sites considered, the predictions of the GIA model agree with the GPS results to within two standard deviations. Most of the GPS velocities showing discrepancies with respect to the predictions of the GIA model are, however, consistent with previously published space geodesy results. We, in turn, confirm the value of 1.8 +/- 0.5 mm yr-1 for the 20th century average global sea level rise, and conclude that GPS is now a robust tool for vertical land motion monitoring which is accurate at least at 1 mm yr-1.

  10. Take-off Stability Characteristics of a 1/13-scale Model of the Consolidated Vultee Skate 7 Seaplane (TED No. NACA DE 338)

    NASA Technical Reports Server (NTRS)

    McKann, Robert; Coffee, Claude W.; Abrabian, Donald D.

    1949-01-01

    The take-off stability characteristics of a Consolidated Vultee Aircraft Corporation Skate 7 seaplane were determined in the Langley tank no. 2. Trim limits of stability, trim tracks, and elevator limits of stability are presented.

  11. Expedition 41 Soyuz TMA-13M Landing

    NASA Image and Video Library

    2014-11-10

    A Russian Search and Rescue helicopter prepares to take off from Kustanay, Kazakhstan to support the Soyuz TMA-13M spacecraft landing with Expedition 41 Commander Max Suraev of the Russian Federal Space Agency (Roscosmos), NASA Flight Engineer Reid Wiseman and Flight Engineer Alexander Gerst of the European Space Agency (ESA) on Monday, Nov. 10, 2014. Suraev, Wiseman and Gerst returned to Earth after more than five months onboard the International Space Station where they served as members of the Expedition 40 and 41 crews. Photo Credit: (NASA/Bill Ingalls)

  12. Expedition 41 Soyuz TMA-13M Landing

    NASA Image and Video Library

    2014-11-10

    Russian Search and Rescue helicopter teams are seen waiting to take off in their helicopter from Kustanay, Kazakhstan to support the Soyuz TMA-13M spacecraft landing with Expedition 41 Commander Max Suraev of the Russian Federal Space Agency (Roscosmos), NASA Flight Engineer Reid Wiseman and Flight Engineer Alexander Gerst of the European Space Agency (ESA) on Monday, Nov. 10, 2014. Suraev, Wiseman and Gerst returned to Earth after more than five months onboard the International Space Station where they served as members of the Expedition 40 and 41 crews. Photo Credit: (NASA/Bill Ingalls)

  13. Expedition 41 Soyuz TMA-13M Landing

    NASA Image and Video Library

    2014-11-10

    Russian Search and Rescue helicopter teams wait to take off from Kustanay, Kazakhstan to support the Soyuz TMA-13M spacecraft landing with Expedition 41 Commander Max Suraev of the Russian Federal Space Agency (Roscosmos), NASA Flight Engineer Reid Wiseman and Flight Engineer Alexander Gerst of the European Space Agency (ESA) on Monday, Nov. 10, 2014. Suraev, Wiseman and Gerst returned to Earth after more than five months onboard the International Space Station where they served as members of the Expedition 40 and 41 crews. Photo Credit: (NASA/Bill Ingalls)

  14. Expedition 41 Soyuz TMA-13M Landing

    NASA Image and Video Library

    2014-11-10

    Russian Search and Rescue helicopter tail rotors are seen as teams wait to take off from Kustanay, Kazakhstan to support the Soyuz TMA-13M spacecraft landing with Expedition 41 Commander Max Suraev of the Russian Federal Space Agency (Roscosmos), NASA Flight Engineer Reid Wiseman and Flight Engineer Alexander Gerst of the European Space Agency (ESA) on Monday, Nov. 10, 2014. Suraev, Wiseman and Gerst returned to Earth after more than five months onboard the International Space Station where they served as members of the Expedition 40 and 41 crews. Photo Credit: (NASA/Bill Ingalls)

  15. Life on an Island: Early Settlers off the Rock Bound Coast of Maine. Teaching with Historic Places.

    ERIC Educational Resources Information Center

    Hobbs-Olson, Laurie

    This lesson, based on National Register of Historic Places files, describes early settlers' lives on some of the approximately 5,000 islands off the coast of Maine. During the mid-18th century many of these islands began to be inhabited by settlers eager to take advantage of this interface between land and sea. The lesson discusses the Blue Duck…

  16. Workers take off the protective covering on Cassini's propulsion module in SAEF-2

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Workers take off the protective covering on the propulsion module for the Cassini spacecraft after uncrating the module at KSC's Spacecraft Assembly and Encapsulation Facility-2 (SAEF-2). The extended journey of 6.7 years to Saturn and the 4-year mission for Cassini once it gets there will require the spacecraft to carry a large amount of propellant for inflight trajectory- correction maneuvers and attitude control, particularly during the science observations. The propulsion module has redundant 445-newton main engines that burn nitrogen tetraoxide and monomethyl-hydrazine for main propulsion and 16 smaller 1-newton engines that burn hydrazine to control attitude and to correct small deviations from the spacecraft flight path. Cassini will be launched on a Titan IVB/Centaur expendable launch vehicle. Liftoff is targeted for October 6 from Launch Complex 40, Cape Canaveral Air Station.

  17. Taking the Steam off Pressure Groups.

    ERIC Educational Resources Information Center

    Ledell, Marjorie A.

    1993-01-01

    School administrators must speak out when single-issue or "stealth" groups threaten to take over a school board. Administrators can help ensure that election campaigns stimulate community debate, discussion, and consensus about educational directions. They must know how to remove the cover from stealth candidates, respond to the public,…

  18. System Design and Nonlinear State-Dependent Riccati Equation Control of an Autonomous Y-4 Tilt-Rotor Aerobot for Martian Exploration

    NASA Astrophysics Data System (ADS)

    Collins, Nathan Scott

    Surrey Space Centre (SSC) has been working on an autonomous fixed-wing all-electric vertical take-off and landing (VTOL) aerobot for the exploration of Mars for several years. SSC's previous designs have incorporated separate vertical lift and horizontal pusher rotors as well as a mono tilt-rotor configuration. The Martian aerobot's novel Y-4 tilt-rotor (Y4TR) design is a combination of two previous SSC designs and a step forward for planetary aerobots. The aerobot will fly as a Y4 multi-rotor during vertical flight and as a conventional flying wing during horizontal flight. The more robust Y4TR configuration utilizes two large fixed coaxial counter rotating rotors and two small tilt-rotors for vertical takeoff. The front tilt-rotors rotate during transition flight into the main horizontal flight configuration. The aerobot is a blended wing design with the wings using the "Zagi 10" airfoil blended to a center cover for the coaxial rotors. The open source design and analysis programs XROTOR, CROTOR, Q-BLADE, XFLR5, and OpenVSP were used to design and model the aerobot's four rotors and body. The baseline mission of the Y4TR remains the same as previously reported and will investigate the Isidis Planitia region on Mars over a month long period using optical sensors during flight and a surface science package when landed. During flight operations the aerobot will take off vertically, transition to horizontal flight, fly for around an hour, transition back to vertical flight, and land vertically. The flight missions will take place close to local noon to maximize power production via solar cells during flight. A nonlinear six degree of freedom (6DoF) dynamic model incorporating aerodynamic models of the aerobot's body and rotors has been developed to model the vertical, transition, and horizontal phases of flight. A nonlinear State-Dependent Riccati Equation (SDRE) controller has been developed for each of these flight phases. The nonlinear dynamic model was

  19. Distributions of larval and juvenile/adult stages of the Antarctic myctophid fish, Electrona antarctica, off Wilkes Land in East Antarctica

    NASA Astrophysics Data System (ADS)

    Moteki, Masato; Fujii, Kentaro; Amakasu, Kazuo; Shimada, Keishi; Tanimura, Atsushi; Odate, Tsuneo

    2017-06-01

    Myctophid fish are an important component of the Southern Ocean food web because of their very high biomass. This study investigated the spatial distributions of larval and juvenile/adult stages of the Antarctic myctophid Electrona antarctica. Fish were sampled in January 2011 and 2012 on a transect along 140°E and in January 2013 along 110°E using two different opening/closing net systems. In total, 1075 specimens of E. antarctica were collected: 948 larvae, 127 juveniles/adults, and 2 in the transformation stage. Most larvae were collected at 5-200 m depth, with diel vertical migration (DVM) not apparent. Larvae were mainly distributed in the Modified Circumpolar Deep Water (-1.5 °C-2.0 °C). By contrast, an analysis of the echogram at 38 kHz and discrete depth samples implied that juveniles/adults undertook DVM except in the continental slope area (65.5°S). As the distribution of krill is limited to the cold water mass (<-1.5 °C) along the continental slope, E. antarctica and krill populations are spatially separated off Wilkes Land during summer. According to the previously estimated larval period of 30-47 days, E. antarctica may spawn in late November to December in the marginal ice zone or near the sea ice edge. This study suggests that the environment related to sea ice provides a nursery ground for early stage larvae of E. antarctica.

  20. Estimation of the Basic Reproductive Ratio for Dengue Fever at the Take-Off Period of Dengue Infection.

    PubMed

    Jafaruddin; Indratno, Sapto W; Nuraini, Nuning; Supriatna, Asep K; Soewono, Edy

    2015-01-01

    Estimating the basic reproductive ratio ℛ 0 of dengue fever has continued to be an ever-increasing challenge among epidemiologists. In this paper we propose two different constructions to estimate ℛ 0 which is derived from a dynamical system of host-vector dengue transmission model. The construction is based on the original assumption that in the early states of an epidemic the infected human compartment increases exponentially at the same rate as the infected mosquito compartment (previous work). In the first proposed construction, we modify previous works by assuming that the rates of infection for mosquito and human compartments might be different. In the second construction, we add an improvement by including more realistic conditions in which the dynamics of an infected human compartments are intervened by the dynamics of an infected mosquito compartment, and vice versa. We apply our construction to the real dengue epidemic data from SB Hospital, Bandung, Indonesia, during the period of outbreak Nov. 25, 2008-Dec. 2012. We also propose two scenarios to determine the take-off rate of infection at the beginning of a dengue epidemic for construction of the estimates of ℛ 0: scenario I from equation of new cases of dengue with respect to time (daily) and scenario II from equation of new cases of dengue with respect to cumulative number of new cases of dengue. The results show that our first construction of ℛ 0 accommodates the take-off rate differences between mosquitoes and humans. Our second construction of the ℛ 0 estimation takes into account the presence of infective mosquitoes in the early growth rate of infective humans and vice versa. We conclude that the second approach is more realistic, compared with our first approach and the previous work.

  1. Vertical land motion along the coast of Louisiana: Integrating satellite altimetry, tide gauge and GPS

    NASA Astrophysics Data System (ADS)

    Dixon, T. H.; A Karegar, M.; Uebbing, B.; Kusche, J.; Fenoglio-Marc, L.

    2017-12-01

    Coastal Louisiana is experiencing the highest rate of relative sea-level rise in North America due to the combination of sea-level rise and subsidence of the deltaic plain. The land subsidence in this region is studied using various techniques, with continuous GPS site providing high temporal resolution. Here, we use high resolution tide-gauge data and advanced processing of satellite altimetry to derive vertical displacements time series at NOAA tide-gauge stations along the coast (Figure 1). We apply state-of-the-art retracking techniques to process raw altimetry data, allowing high accuracy on range measurements close to the coast. Data from Jason-1, -2 and -3, Envisat, Saral and Cryosat-2 are used, corrected for solid Earth tide, pole tide and tidal ocean loading, using background models consistent with the GPS processing technique. We reprocess the available GPS data using precise point positioning and estimate the rate uncertainty accounting for correlated noise. The displacement time series are derived by directly subtracting tide-gauge data from the altimetry sea-level anomaly data. The quality of the derived displacement rates is evaluated in Grand Isle, Amerada Pass and Shell Beach where GPS data are available adjacent to the tide gauges. We use this technique to infer vertical displacement at tide gauges in New Orleans (New Canal Station) and Port Fourchon and Southwest Pass along the coastline.

  2. Using Optimal Land-Use Scenarios to Assess Trade-Offs between Conservation, Development, and Social Values.

    PubMed

    Adams, Vanessa M; Pressey, Robert L; Álvarez-Romero, Jorge G

    2016-01-01

    Development of land resources can contribute to increased economic productivity but can also negatively affect the extent and condition of native vegetation, jeopardize the persistence of native species, reduce water quality, and erode ecosystem services. Spatial planning must therefore balance outcomes for conservation, development, and social goals. One approach to evaluating these trade-offs is scenario planning. In this paper we demonstrate methods for incorporating stakeholder preferences into scenario planning through both defining scenario objectives and evaluating the scenarios that emerge. In this way, we aim to develop spatial plans capable of informing actual land-use decisions. We used a novel approach to scenario planning that couples optimal land-use design and social evaluation of environmental outcomes. Four land-use scenarios combined differences in total clearing levels (10% and 20%) in our study region, the Daly Catchment Australia, with the presence or absence of spatial precincts to concentrate irrigated agriculture. We used the systematic conservation planning tool Marxan with Zones to optimally plan for multiple land-uses that met objectives for both conservation and development. We assessed the performance of the scenarios in terms of the number of objectives met and the degree to which existing land-use policies were compromised (e.g., whether clearing limits in existing guidelines were exceeded or not). We also assessed the land-use scenarios using expected stakeholder satisfaction with changes in the catchment to explore how the scenarios performed against social preferences. There were a small fraction of conservation objectives with high conservation targets (100%) that could not be met due to current land uses; all other conservation and development objectives were met in all scenarios. Most scenarios adhered to the existing clearing guidelines with only marginal exceedances of limits, indicating that the scenario objectives were

  3. Using Optimal Land-Use Scenarios to Assess Trade-Offs between Conservation, Development, and Social Values

    PubMed Central

    Pressey, Robert L.; Álvarez-Romero, Jorge G.

    2016-01-01

    Development of land resources can contribute to increased economic productivity but can also negatively affect the extent and condition of native vegetation, jeopardize the persistence of native species, reduce water quality, and erode ecosystem services. Spatial planning must therefore balance outcomes for conservation, development, and social goals. One approach to evaluating these trade-offs is scenario planning. In this paper we demonstrate methods for incorporating stakeholder preferences into scenario planning through both defining scenario objectives and evaluating the scenarios that emerge. In this way, we aim to develop spatial plans capable of informing actual land-use decisions. We used a novel approach to scenario planning that couples optimal land-use design and social evaluation of environmental outcomes. Four land-use scenarios combined differences in total clearing levels (10% and 20%) in our study region, the Daly Catchment Australia, with the presence or absence of spatial precincts to concentrate irrigated agriculture. We used the systematic conservation planning tool Marxan with Zones to optimally plan for multiple land-uses that met objectives for both conservation and development. We assessed the performance of the scenarios in terms of the number of objectives met and the degree to which existing land-use policies were compromised (e.g., whether clearing limits in existing guidelines were exceeded or not). We also assessed the land-use scenarios using expected stakeholder satisfaction with changes in the catchment to explore how the scenarios performed against social preferences. There were a small fraction of conservation objectives with high conservation targets (100%) that could not be met due to current land uses; all other conservation and development objectives were met in all scenarios. Most scenarios adhered to the existing clearing guidelines with only marginal exceedances of limits, indicating that the scenario objectives were

  4. Second harmonic generation of off axial vortex beam in the case of walk-off effect

    NASA Astrophysics Data System (ADS)

    Chen, Shunyi; Ding, Panfeng; Pu, Jixiong

    2016-07-01

    Process of off axial vortex beam propagating in negative uniaxial crystal is investigated in this work. Firstly, we get the formulae of the normalized electric field and calculate the location of vortices for second harmonic beam in two type of phase matching. Then, numerical analysis verifies that the intensity distribution and location of vortices of the first order original vortex beam depend on the walk-off angle and off axial magnitude. It is shown that, in type I phase matching, the distribution of vortices is symmetrical about the horizontal axis, the separation distance increases as the off axial magnitude increases or the off axial magnitude deceases. However, in type II phase matching, the vortices are symmetrical along with some vertical axis, and increase of the walk-off angle or off axial magnitude leads to larger separation distance. Finally, the case of high order original off axial vortex beam is also investigated.

  5. Simulator study of minimum acceptable level of longitudinal stability for a representative STOL configuration during landing approach

    NASA Technical Reports Server (NTRS)

    Grantham, W. D.; Deal, P. L.

    1974-01-01

    A fixed-base simulator study was conducted to determine the minimum acceptable level of longitudinal stability for a representative turbofan STOL (short take-off and landing) transport airplane during the landing approach. Real-time digital simulation techniques were used. The computer was programed with equations of motion for six degrees of freedom, and the aerodynamic inputs were based on measured wind-tunnel data. The primary piloting task was an instrument approach to a breakout at a 60-m (200-ft) ceiling.

  6. The Application Research of National Geography Census Data in the Departmental Investigation and Management-Taking Land Management as AN Example

    NASA Astrophysics Data System (ADS)

    Jiang, N.

    2018-04-01

    According to the "Natural priority, Status quo priority" principle of acquisition, the national geography census data has the characteristics of objectivity, impartiality and accuracy. It provides a new perspective for the management and decision-making support of other industries as a "third party" and plays an important role in the professional management and investigation of various departments including land, transportation, forestry and water conservancy. Taking land resources supervision as an example, the Yellow River Delta efficient eco-economic zone as the research area, based on the national geographic census data and the land survey data, this paper established the correspondence of the two types of data through the reclassification of the land cover classification data, calculated the spatial coincidence rate of the same land class and the circulation relations among different land classes through the spatial overlay analysis and the calculation of space transfer matrix, quantified the differences between the data and objectively analysed the causes of the differences; On this basis, combined with land supervision hot spots, supplemented by multi-source remote sensing images and socio-economic data, analysed the application of geographic census data in the land regulation from multi-point.

  7. A Simulation Study on Take-Off and Landing Dynamics of the Aircraft of a Fly-By-Wire Control System

    DTIC Science & Technology

    1993-01-07

    L:V,"DIN G DYN;AMICS OF THE AIRCRAFT OF A FLY-BY-WIRE CONTROL SYSTEM by Y achang Feng, Gang Chert, Peiqiong Li 93-00985 Distribution unlimit ed. FASTC...FLY-BY-WIRE CONTROL SYSTEM By: Yachang Feng, Gang Chen, Peiqiong- Li English pages: 17 Source: Hangkon, Xuebao, Vol. 12, No. 6, June, 1991; pp. 252-258...Landing Dynamics of the Aircraft of a Fly-By-Wire Control System Beijing University of Aeronautics and Astronautics Yachang FENG, Gang CHEN and Peiqiong Li

  8. Aircraft landing control system

    NASA Technical Reports Server (NTRS)

    Lambregts, Antonius A. (Inventor); Hansen, Rolf (Inventor)

    1982-01-01

    Upon aircraft landing approach, flare path command signals of altitude, vertical velocity and vertical acceleration are generated as functions of aircraft position and velocity with respect to the ground. The command signals are compared with corresponding actual values to generate error signals which are used to control the flight path.

  9. VSTOL Systems Research Aircraft (VSRA) Harrier

    NASA Technical Reports Server (NTRS)

    1994-01-01

    NASA's Ames Research Center has developed and is testing a new integrated flight and propulsion control system that will help pilots land aircraft in adverse weather conditions and in small confined ares (such as, on a small ship or flight deck). The system is being tested in the V/STOL (Vertical/Short Takeoff and Landing) Systems research Aircraft (VSRA), which is a modified version of the U.S. Marine Corps's AV-8B Harrier jet fighter, which can take off and land vertically. The new automated flight control system features both head-up and panel-mounted computer displays and also automatically integrates control of the aircraft's thrust and thrust vector control, thereby reducing the pilot's workload and help stabilize the aircraft for landing. Visiting pilots will be encouraged to test the new system and provide formal evaluation flights data and feedback. An actual flight test and the display panel of control system are shown in this video.

  10. First fabrication of a silicon vertical JFET for power distribution in high energy physics applications

    NASA Astrophysics Data System (ADS)

    Fernández-Martínez, Pablo; Flores, D.; Hidalgo, S.; Quirion, D.; Durà, R.; Ullán, M.

    2018-01-01

    A new vertical JFET transistor has been recently developed at the IMB-CNM, taking advantage of a deep-trenched 3D technology to achieve vertical conduction and low switch-off voltage. The silicon V-JFET transistors were mainly conceived to work as rad-hard protection switches for the renewed HV powering scheme (HV-MUX) of the ATLAS upgraded tracker. This work presents the features of the first batch of V-JFETs produced at the IMB-CNM clean room, together with the results of a full pre-irradiation characterization of the fabricated prototypes. Details of the technological process are provided and the outcome quality is also evaluated with the aid of reverse engineering techniques. Concerning the electrical performance of the prototypes, promising results were obtained, already meeting most of the HV-MUX specifications, both at room and below-zerotemperatures.

  11. Expedition 41 Soyuz TMA-13M Landing

    NASA Image and Video Library

    2014-11-10

    A Russian search and rescue helicopter crew waits for the weather to clear before taking off from Kustanay, Kazakhstan to support the Soyuz TMA-13M spacecraft landing with Expedition 41 Commander Max Suraev of the Russian Federal Space Agency (Roscosmos), NASA Flight Engineer Reid Wiseman and Flight Engineer Alexander Gerst of the European Space Agency (ESA) on Monday, Nov. 10, 2014. Suraev, Wiseman and Gerst returned to Earth after more than five months onboard the International Space Station where they served as members of the Expedition 40 and 41 crews. Photo Credit: (NASA/Bill Ingalls)

  12. 14 CFR 25.479 - Level landing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... vertical ground reactions calculated from paragraph (a), the following apply: (1) The landing gear and directly affected attaching structure must be designed for the maximum vertical ground reaction combined with an aft acting drag component of not less than 25% of this maximum vertical ground reaction. (2...

  13. Air transportation systems for the California corridor of 2010

    NASA Technical Reports Server (NTRS)

    1988-01-01

    In 1986 NASA and USRA identified Cal Poly as one of seven 'Centers of Aircraft Design Education', and accepted a proposal from Cal Poly to conduct a three-year study of the potential for Lighter-Than-Air (LTA), Vertical Take-Off and Landing (VTOL), and Short Take-Off and landing (STOL) aircraft concepts for air transportation within the California corridor. The project emphasizes configurations that are both innovative and unconventional in design for use in the 2010 time period. The topic of LTA/VTOL/STOL aircraft was selected because it is consistent with the mission of the NASA Ames Research Center and is a broad topic that succeeding classes at Cal Poly can continue to iterate and refine to produce meaningful results for NASA. Along with studying the technical issues normally involved in any aircraft design problem, the topics of safety, noise, public acceptance, and economic viability in commercial operations are also addressed.

  14. Astronaut candidate Koichi Wakata (left) prepares to jump off a box during a parachute landing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    1992 ASCAN TRAINING --- Astronaut candidate Koichi Wakata (left) prepares to jump off a box during a parachute landing demonstration at Vance Air Force Base. This portion of the training is designed to familiarize the trainees with the proper way to hit the ground following a parachute jump. Looking on is astronaut candidate Andrew W. S. Thomas. Wakata is one of seven international mission specialist candidates who joined 19 United States astronaut candidates, including Thomas, for the three-day parachute/survival training school at the Oklahoma Base.EDITORS NOTE: Since this photograph was taken, Wakata has been named as mission specialist for the STS-72 mission and Thomas has been named as mission specialist for the STS-77 flight.

  15. TRMM Precipitation Radar and Microwave Imager Observations of Convective and Stratiform Rain Over Land and Their Theoretical Implications

    NASA Technical Reports Server (NTRS)

    Prabhakara, C.; Iacovazzi, R., Jr.; Yoo, J.-M.; Weinman, J. A.; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Observations of brightness temperature, Tb made over land regions by the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) radiometer have been analyzed along with the nearly simultaneous measurements of the vertical profiles of reflectivity factor, Z, made by the Precipitation Radar (PR) onboard the TRMM satellite. This analysis is performed to explore the interrelationship between the TMI and PR data in areas that are covered predominantly by convective or stratiform rain. In particular, we have compared on a scale of 20 km, average vertical profiles of Z with the averages of Tbs in the 19, 37 and 85 GHz channels. Generally, we find from these data that as Z increases, Tbs in the three channels decrease due to extinction. In order to explain physically the relationship between the Tb and Z observations, we have performed radiative transfer simulations utilizing vertical profiles of hydrometeors applicable to convective and stratiform rain regions. These profiles are constructed taking guidance from the Z observations of PR and recent LDR and ZDR measurements made by land-based polarimetric radars.

  16. Trunk Muscle Activation and Estimating Spinal Compressive Force in Rope and Harness Vertical Dance.

    PubMed

    Wilson, Margaret; Dai, Boyi; Zhu, Qin; Humphrey, Neil

    2015-12-01

    Rope and harness vertical dance takes place off the floor with the dancer suspended from his or her center of mass in a harness attached to a rope from a point overhead. Vertical dance represents a novel environment for training and performing in which expected stresses on the dancer's body are different from those that take place during dance on the floor. Two male and eleven female dancers with training in vertical dance performed six typical vertical dance movements with electromyography (EMG) electrodes placed bilaterally on rectus abdominus, external oblique, erector spinae, and latissimus dorsi. EMG data were expressed as a percentage of maximum voluntary isometric contraction (MVIC). A simplified musculoskeletal model based on muscle activation for these four muscle groups was used to estimate the compressive force on the spine. The greatest muscle activation for erector spinae and latissimus dorsi and the greatest trunk compressive forces were seen in vertical axis positions where the dancer was moving the trunk into a hyper-extended position. The greatest muscle activation for rectus abdominus and external oblique and the second highest compressive force were seen in a supine position with the arms and legs extended away from the center of mass (COM). The least muscle activation occurred in positions where the limbs were hanging below the torso. These movements also showed relatively low muscle activation compression forces. Post-test survey results revealed that dancers felt comfortable in these positions; however, observation of some positions indicated insufficient muscular control. Computing the relative contribution of muscles, expressed as muscle activation and estimated spinal compression, provided a measure of how much the muscle groups were working to support the spine and the rest of the dancer's body in the different movements tested. Additionally, identifying typical muscle recruitment patterns in each movement will help identify key exercises

  17. Effects of the rider on the linear kinematics of jumping horses.

    PubMed

    Powers, Pippa; Harrison, Andrew

    2002-07-01

    This study examined the effects of the rider on the linear projectile kinematics of show-jumping horses. SVHS video recordings (50 Hz) of eight horses jumping a vertical fence 1 m high were used for the study. Horses jumped the fence under two conditions: loose (no rider or tack) and ridden. Recordings were digitised using Peak Motus. After digitising the sequences, each rider's digitised data were removed from the ridden horse data so that three conditions were examined: loose, ridden (including the rider's data) and riderless (rider's data removed). Repeated measures ANOVA revealed significant differences between ridden and loose conditions for CG height at take-off (p < 0.001), CG distance to the fence at take-off (p = 0.001), maximum CG during the suspension phase (p < 0.001), CG position over the centre of the fence (p < 0.001), CG height at landing (p < 0.001), and vertical velocity at take-off (p < 0.001). The results indicated that the rider's effect on jumping horses was primarily due to behavioural changes in the horses motion (resulting from the rider's instruction), rather than inertial effects (due to the positioning of the rider on the horse). These findings have implications for the coaching of riders and horses.

  18. Power Take-off System for Marine Renewable Devices, CRADA Number CRD-14-566

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

    Muljadi, Eduard

    Ocean Renewable Power Company (ORPC) proposes a project to develop and test innovative second-generation power take-off (PTO) components for the U.S. Department of Energy's 2013 FOA: Marine and Hydrokinetic System Performance Advancement, Topic Area 2 (Project). Innovative PTO components will include new and improved designs for bearings, couplings and a subsea electrical generator. Specific project objectives include the following: (1) Develop components for an advanced PTO suitable for MHK devices; (2) Bench test these components; (3) Assess the component and system performance benefits; (4) Perform a system integration study to integrate these components into an ORPC hydrokinetic turbine. National Renewablemore » Energy Laboratory (NREL) will participate on the ORPC lead team to review design of the generator and will provide guidance on the design. Based on inputs from the project team, NREL will also provide an economic analysis of the impacts of the proposed system performance advancements.« less

  19. Final Scientific/Technical Report: ADVANCED INTEGRATION OF POWER TAKE-OFF IN VIVACE

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

    Simiao, Gustavo

    2014-03-21

    Vortex Hydro Energy is commercializing a University of Michigan patented MHK device, the VIVACE converter (Vortex Induced Vibration Aquatic Clean Energy). Unlike water turbines, it does not use propeller blades. Rather, river or ocean currents flow around cylinders causing them to move up and down in Flow Induced Motions (FIM). This kinetic energy of the cylinder is then converted to electricity. Importantly, the VIVACE converter is simpler in design and more cost effective than water turbines. This project accelerated the development of the VIVACE technology. Funding from the DOE enabled VHE to accelerate the development in three ways. One wasmore » to increase the efficiency of the hydrodynamics of the system. This aided in maximizing the power output for a wide range of water speeds. The second was to design, build, and test an efficient power take-off (PTO) that converted the most power from the VIVACE cylinders into electricity. This effort was necessary because of the nature of power generated using this technology. Although the PTO uses off-the-shelf components, it is specifically tuned to the specific water flow characteristics. The third way the development was accelerated was by testing the improved Beta 1B prototype over a longer period of time in a river. The greatest benefit from the longer open-water testing-period is a better understand of the power generation characteristics of the system as well as the maintenance lifespan of the device. Renewable energy generation is one of today’s most challenging global dilemmas. The energy crisis requires tapping into every source of energy and developing every technology that can generate energy at a competitive cost within the next 50 years. Development of VIVACE will bolster domestic energy security and mitigate global climate change. There are numerous commercial and military applications for a fully developed system, which could generate clean/renewable energy from small scale (1-5kW) to medium scale

  20. Landing Characteristics of a Lenticular-Shaped Reentry Vehicle

    NASA Technical Reports Server (NTRS)

    Blanchard, Ulysse J.

    1961-01-01

    An experimental investigation was made of the landing characteristics of a 1/9-scale dynamic model of a lenticular-shaped reentry vehicle having extendible tail panels for control after reentry and for landing control (flare-out). The landing tests were made by catapulting a free model onto a hard-surface runway and onto water. A "belly-landing" technique in which the vehicle was caused to skid and rock on its curved undersurface (heat shield), converting sinking speed into angular energy, was investigated on a hard-surface runway. Landings were made in calm water and in waves both with and without auxiliary landing devices. Landing motions and acceleration data were obtained over a range of landing attitudes and initial sinking speeds during hard-surface landings and for several wave conditions during water landings. A few vertical landings (parachute letdown) were made in calm water. The hard-surface landing characteristics were good. Maximum landing accelerations on a hard surface were 5g and 18 radians per sq second over a range of landing conditions. Horizontal landings on water resulted in large violent rebounds and some diving in waves. Extreme attitude changes during rebound at initial impact made the attitude of subsequent impact random. Maximum accelerations for water landings were approximately 21g and 145 radians per sq second in waves 7 feet high. Various auxiliary water-landing devices produced no practical improvement in behavior. Reduction of horizontal speed and positive control of impact attitude did improve performance in calm water. During vertical landings in calm water maximum accelerations of 15g and 110 radians per sq second were measured for a contact attitude of -45 deg and a vertical velocity of 70 feet per second.

  1. Numerical flow simulation of a reusable sounding rocket during nose-up rotation

    NASA Astrophysics Data System (ADS)

    Kuzuu, Kazuto; Kitamura, Keiichi; Fujimoto, Keiichiro; Shima, Eiji

    2010-11-01

    Flow around a reusable sounding rocket during nose-up rotation is simulated using unstructured compressible CFD code. While a reusable sounding rocket is expected to reduce the cost of the flight management, it is demanded that this rocket has good performance for wide range of flight conditions from vertical take-off to vertical landing. A rotating body, which corresponds to a vehicle's motion just before vertical landing, is one of flight environments that largely affect its aerodynamic design. Unlike landing of the space shuttle, this vehicle must rotate from gliding position to vertical landing position in nose-up direction. During this rotation, the vehicle generates massive separations in the wake. As a result, induced flow becomes unsteady and could have influence on aerodynamic characteristics of the vehicle. In this study, we focus on the analysis of such dynamic characteristics of the rotating vehicle. An employed numerical code is based on a cell-centered finite volume compressible flow solver applied to a moving grid system. The moving grid is introduced for the analysis of rotating motion. Furthermore, in order to estimate an unsteady turbulence, we employed DDES method as a turbulence model. In this simulation, flight velocity is subsonic. Through this simulation, we discuss the effect on aerodynamic characteristics of a vehicle's shape and motion.

  2. A Summary of the NASA Design Environment for Novel Vertical Lift Vehicles (DELIVER) Project

    NASA Technical Reports Server (NTRS)

    Theodore, Colin R.

    2018-01-01

    The number of new markets and use cases being developed for vertical take-off and landing vehicles continues to explode, including the highly publicized urban air taxi and package deliver applications. There is an equally exploding variety of novel vehicle configurations and sizes that are being proposed to fill these new market applications. The challenge for vehicle designers is that there is currently no easy and consistent way to go from a compelling mission or use case to a vehicle that is best configured and sized for the particular mission. This is because the availability of accurate and validated conceptual design tools for these novel types and sizes of vehicles have not kept pace with the new markets and vehicles themselves. The Design Environment for Novel Vertical Lift Vehicles (DELIVER) project was formulated to address this vehicle design challenge by demonstrating the use of current conceptual design tools, that have been used for decades to design and size conventional rotorcraft, applied to these novel vehicle types, configurations and sizes. In addition to demonstrating the applicability of current design and sizing tools to novel vehicle configurations and sizes, DELIVER also demonstrated the addition of key transformational technologies of noise, autonomy, and hybrid-electric and all-electric propulsion into the vehicle conceptual design process. Noise is key for community acceptance, autonomy and the need to operate autonomously are key for efficient, reliable and safe operations, and electrification of the propulsion system is a key enabler for these new vehicle types and sizes. This paper provides a summary of the DELIVER project and shows the applicability of current conceptual design and sizing tools novel vehicle configurations and sizes that are being proposed for urban air taxi and package delivery type applications.

  3. Drop and Flight Tests on NY-2 Landing Gears Including Measurements of Vertical Velocities at Landing

    NASA Technical Reports Server (NTRS)

    Peck, W D; Beard, A P

    1933-01-01

    This investigation was conducted to obtain quantitative information on the effectiveness of three landing gears for the NY-2 (consolidated training) airplane. The investigation consisted of static, drop, and flight tests on landing gears of the oleo-rubber-disk and the mercury rubber-chord types, and flight tests only on a landing gear of the conventional split-axle rubber-cord type. The results show that the oleo gear is the most effective of the three landing gears in minimizing impact forces and in dissipating the energy taken.

  4. Preliminary performance of a vertical-attitude takeoff and landing, supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system

    NASA Technical Reports Server (NTRS)

    Robins, A. W.; Beissner, F. L., Jr.; Domack, C. S.; Swanson, E. E.

    1985-01-01

    A performance study was made of a vertical attitude takeoff and landing (VATOL), supersonic cruise aircraft concept having thrust vectoring integrated into the flight control system. Those characteristics considered were aerodynamics, weight, balance, and performance. Preliminary results indicate that high levels of supersonic aerodynamic performance can be achieved. Further, with the assumption of an advanced (1985 technology readiness) low bypass ratio turbofan engine and advanced structures, excellent mission performance capability is indicated.

  5. A New Global Vertical Land Movement Data Set from the TIGA Combined Solution

    NASA Astrophysics Data System (ADS)

    Hunegnaw, Addisu; Teferle, Felix Norman; Ebuy Abraha, Kibrom; Santamaría-Gómez, Alvaro; Gravelle, Médéric; Wöppelman, Guy; Schöne, Tilo; Deng, Zhiguo; Bingley, Richard; Hansen, Dionne Nicole; Sanchez, Laura; Moore, Michael; Jia, Minghai

    2017-04-01

    Globally averaged sea level has been estimated from the network of tide gauges installed around the world since the 19th century. These mean sea level (MSL) records provide sea level relative to a nearby tide gauge benchmark (TGBM), which allows for the continuation of the instrumental record in time. Any changes in the benchmark levels, induced by vertical land movements (VLM) affect the MSL records and hence sea level estimates. Over the last two decades sea level has also been observed using satellite altimeters. While the satellite observations are globally more homogeneous providing a picture of sea level not confined to coastlines, they require the VLM-corrected MSL records for the bias calibration of instrumental drifts. Without this calibration altimeter instruments from different missions cannot be combined. GPS has made it possible to obtain highly accurate estimates of VLM in a geocentric reference frame for stations at or close to tide gauges. Under the umbrella of the International GNSS Service (IGS), the Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG) has been established to apply the expertise of the GNSS community to solving issues related to the accuracy and reliability of the vertical component to provide estimates of VLM in a well-defined global reference frame. To achieve this objective, five TIGA Analysis Centers (TACs) contributed re-processed global GPS network solutions to TIGA, employing the latest bias models and processing strategies in accordance with the second re-processing campaign (repro2) of the IGS. These solutions include those of the British Isles continuous GNSS Facility - University of Luxembourg consortium (BLT), the German Research Centre for Geosciences (GFZ) Potsdam, the German Geodetic Research Institute (DGF) at the Technical University of Munich, Geoscience Australia (AUT) and the University of La Rochelle (ULR). In this study we present to the sea level community an evaluation of the VLM estimates from the

  6. Enabling efficient vertical takeoff/landing and forward flight of unmanned aerial vehicles: Design and control of tandem wing-tip mounted rotor mechanisms

    NASA Astrophysics Data System (ADS)

    Mancuso, Peter Timothy

    Fixed-wing unmanned aerial vehicles (UAVs) that offer vertical takeoff and landing (VTOL) and forward flight capability suffer from sub-par performance in both flight modes. Achieving the next generation of efficient hybrid aircraft requires innovations in: (i) power management, (ii) efficient structures, and (iii) control methodologies. Existing hybrid UAVs generally utilize one of three transitioning mechanisms: an external power mechanism to tilt the rotor-propulsion pod, separate propulsion units and rotors during hover and forward flight, or tilt body craft (smaller scale). Thus, hybrid concepts require more energy compared to dedicated fixed-wing or rotorcraft UAVs. Moreover, design trade-offs to reinforce the wing structure (typically to accommodate the propulsion systems and enable hover, i.e. tilt-rotor concepts) adversely impacts the aerodynamics, controllability and efficiency of the aircraft in both hover and forward flight modes. The goal of this research is to develop more efficient VTOL/ hover and forward flight UAVs. In doing so, the transition sequence, transition mechanism, and actuator performance are heavily considered. A design and control methodology was implemented to address these issues through a series of computer simulations and prototype benchtop tests to verify the proposed solution. Finally, preliminary field testing with a first-generation prototype was conducted. The methods used in this research offer guidelines and a new dual-arm rotor UAV concept to designing more efficient hybrid UAVs in both hover and forward flight.

  7. Off-Road and the Fragile Desert

    ERIC Educational Resources Information Center

    Stebbins, Robert C.

    1974-01-01

    Part one of a two-part article sets forth the dimensions and the political-cultural aspects of the use of off-road vehicles in desert areas. Presents arguments for and against off-road vehicle use on national-resource land as exemplified in the California Desert. (Editor/JR)

  8. A comparison of methods to estimate vertical land motion trends from GNSS and altimetry at tide gauge stations

    NASA Astrophysics Data System (ADS)

    Kleinherenbrink, Marcel; Riva, Riccardo; Frederikse, Thomas

    2018-03-01

    Tide gauge (TG) records are affected by vertical land motion (VLM), causing them to observe relative instead of geocentric sea level. VLM can be estimated from global navigation satellite system (GNSS) time series, but only a few TGs are equipped with a GNSS receiver. Hence, (multiple) neighboring GNSS stations can be used to estimate VLM at the TG. This study compares eight approaches to estimate VLM trends at 570 TG stations using GNSS by taking into account all GNSS trends with an uncertainty smaller than 1 mm yr-1 within 50 km. The range between the methods is comparable with the formal uncertainties of the GNSS trends. Taking the median of the surrounding GNSS trends shows the best agreement with differenced altimetry-tide gauge (ALT-TG) trends. An attempt is also made to improve VLM trends from ALT-TG time series. Only using highly correlated along-track altimetry and TG time series reduces the SD of ALT-TG time series by up to 10 %. As a result, there are spatially coherent changes in the trends, but the reduction in the root mean square (RMS) of differences between ALT-TG and GNSS trends is insignificant. However, setting correlation thresholds also acts like a filter to remove problematic TG time series. This results in sets of ALT-TG VLM trends at 344-663 TG locations, depending on the correlation threshold. Compared to other studies, we decrease the RMS of differences between GNSS and ALT-TG trends (from 1.47 to 1.22 mm yr-1), while we increase the number of locations (from 109 to 155), Depending on the methods the mean of differences between ALT-TG and GNSS trends vary between 0.1 and 0.2 mm yr-1. We reduce the mean of the differences by taking into account the effect of elastic deformation due to present-day mass redistribution. At varying ALT-TG correlation thresholds, we provide new sets of trends for 759 to 939 different TG stations. If both GNSS and ALT-TG trend estimates are available, we recommend using the GNSS trend estimates because residual

  9. Virtual reality implementation in neurosurgical practice: the "can't take my eyes off you" effect.

    PubMed

    Matis, Georgios K; Silva, Danilo O de A; Chrysou, Olga I; Karanikas, Michail; Pelidou, Sygkliti-Henrietta; Birbilis, Theodossios A; Bernardo, Antonio; Stieg, Philip

    2013-01-01

    During the last few years, virtual reality (VR) has been increasingly implemented in the neurosurgical practice. The scope of this paper is to briefly outline the educational role of this novel technology in training surgeons. At the same time, the ability of VR workstations such as the Dextroscope® to consistently simulate the surgical trajectory to the lesion-target is highlighted. The authors shed light to the current applications of VR systems in the neurosurgical field by describing not only the advantages of those systems, but their principal drawbacks as well. It seems that VR has come to stay and it is already the new best friend of residents due to its "Can't take my eyes off you effect".

  10. Effects of Prophylactic Ankle Supports on Vertical Ground Reaction Force During Landing: A Meta-Analysis.

    PubMed

    Niu, Wenxin; Feng, Tienan; Wang, Lejun; Jiang, Chenghua; Zhang, Ming

    2016-03-01

    There has been much debate on how prophylactic ankle supports (PASs) may influence the vertical ground reaction force (vGRF) during landing. Therefore, the primary aims of this meta-analysis were to systematically review and synthesize the effect of PASs on vGRF, and to understand how PASs affect vGRF peaks (F1, F2) and the time from initial contact to peak loading (T1, T2) during landing. Several key databases, including Scopus, Cochrane, Embase, PubMed, ProQuest, Medline, Ovid, Web of Science, and the Physical Activity Index, were used for identifying relevant studies published in English since inception to April 1, 2015. The computerized literature search and cross-referencing the citation list of the articles yielded 3,993 articles. Criteria for inclusion required that 1) the study was conducted on healthy adults; 2) the subject number and trial number were known; 3) the subjects performed landing with and without PAS; 4) the landing movement was in the sagittal plane; 5) the comparable vGRF parameters were reported; and 6) the F1 and F2 must be normalized to the subject's body weight. After the removal of duplicates and irrelevant articles, 6, 6, 15 and 11 studies were respectively pooled for outcomes of F1, T1, F2 and T2. This study found a significantly increased F2 (.03 BW, 95% CI: .001, .05) and decreased T1 (-1.24 ms, 95% CI: -1.77, -.71) and T2 (-3.74 ms, 95% CI: -4.83, -2.65) with the use of a PAS. F1 was not significantly influenced by the PAS. Heterogeneity was present in some results, but there was no evidence of publication bias for any outcome. These changes represented deterioration in the buffering characteristics of the joint. An ideal PAS design should limit the excessive joint motion of ankle inversion, while allowing a normal range of motion, especially in the sagittal plane. Key pointsPAS can effectively protect the ligamentous structure from spraining by providing mechanical support and cutaneous proprioceptive benefits.Using of PAS can

  11. Maritime Tactical Unmanned Aerial Systems (TUAS) in Navy Strike Groups Can Improve Maritime Domain Awareness for the Operational Commander

    DTIC Science & Technology

    2008-10-31

    Proposal, staff study, 5 September 2007. 4 Thomas H. Kean, and Lee Hamilton. The 9/11 Commission Report: Final Report of the National...January 2008. http://www.cnaf.navy.mil/nae/main.asp?ItemID=12.   41  Tim Dunigan, “Vertical Take-off and Landing Tactical Unmanned Air Vehicle...September 2007. Berner , Robert A. The Effective Use of Multiple Unmanned Aerial Vehicles in Surface Search and Control. Ft. Belvoir: Defense

  12. A NASA study of the impact of technology on future carrier based tactical aircraft - Overview

    NASA Technical Reports Server (NTRS)

    Wilson, S. B., III

    1992-01-01

    This paper examines the impact of technology on future carrier based tactical aircraft. The results were used in the Center for Naval Analysis Future Carrier Study. The NASA Team designed three classes of aircraft ('Fighter', 'Attack', and 'Multimission') with two different technology levels. The Multimission aircraft were further analyzed by examining the penalty on the aircraft for both catapult launch/arrested landing recovery (Cat/trap) and short take-off/vertical landing (STOVL). The study showed the so-called STOVL penalty was reduced by engine technology and the next generation Strike Fighter will pay more penalty for Cat/trap than for STOVL capability.

  13. 14 CFR 29.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

  14. 14 CFR 29.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

  15. 14 CFR 27.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

  16. 14 CFR 27.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

  17. 14 CFR 27.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

  18. 14 CFR 29.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical... load of 0.8 times the vertical reaction combined with the vertical load specified in paragraph (a) of...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing...

  19. The influence of land use on the concentration and vertical distribution of PBDEs in soils of an e-waste recycling region of South China.

    PubMed

    Cheng, Zhineng; Wang, Yan; Wang, Shaorui; Luo, Chunling; Li, Jun; Chaemfa, Chakra; Jiang, Haoyu; Zhang, Gan

    2014-08-01

    The vertical distribution of polybrominated diphenyl ethers (PBDEs) in soil at four sites within an e-waste recycling region of South China was investigated. PBDE concentrations in soil ranged from 1.38 to 765 ng/g. There was a trend of decreasing PBDE concentration with soil depth, especially in the paddy field. However, high concentrations of BDE-209 were found in deeper soils indicating a highly preferential migration. There was a stronger correlation between PBDEs and total organic carbon (TOC), compared to dissolved organic carbon (DOC), which suggests that the association between non-dissolved organic carbon (NDOC) and PBDEs is stronger than for DOC. Different land use types, in particular differences in farming activities, significantly influenced the vertical distribution of PBDEs in soils. PBDEs displayed a higher leaching tendency in moist paddy soil than in drier soils. The frequent flooding condition in paddy field may facilitate the vertical transfer of PBDEs to the deeper soils. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Effects of off-road recreation on mule deer and elk.

    Treesearch

    Michael J. Wisdom; Alan A. Ager; Haiganoush K. Preisler; Norman J. Cimon; Bruce K. Johnson

    2004-01-01

    Off-road recreation is increasing rapidly in the United States, especially on public land (Havlick 2002, U.S. Department of Agriculture Forest Service 2004). An expansive network of roads provides easy access to much public land, which facilitates off-road uses in the form of all-terrain vehicles (ATVs), horses, mountain bikes and foot traffic. No research, however,...

  1. Investigation of shortcomings in simulated aerosol vertical profiles

    NASA Astrophysics Data System (ADS)

    Park, S.; Allen, R.

    2017-12-01

    The vertical distribution of aerosols is one important factor for aerosol radiative forcing. Previous studies show that climate models poorly reproduce the aerosol vertical profile, with too much aerosol aloft in the upper troposphere. This bias may be related to several factors, including excessive convective mass flux and wet removal. In this study, we evaluate the aerosol vertical profile from several Coupled Model Intercomparison Project 5 (CMIP5) models, as well as the Community Atmosphere Model 5 (CAM5), relative to the Cloud-Aerosol Lidar Infrared Pathfinder Satellite Observation (CALIPSO). The results show that all models significantly underestimate extinction coefficient in the lower troposphere, while overestimating extinction coefficient in the upper troposphere. In addition, the majority of models indicate a land-ocean dependence in the relationship between aerosol extinction coefficient in the upper troposphere and convective mass flux. Over the continents, more convective mass flux is related to more aerosol aloft; over the ocean, more convective mass flux is associated with less aerosol in upper troposphere. Sensitivity experiments are conducted to investigate the role that convection and wet deposition have in contributing to the deficient simulation of the vertical aerosol profile, including the land-ocean dependence.

  2. Astronaut candidate Koichi Wakata prepares to jump off a box during a parachute landing

    NASA Technical Reports Server (NTRS)

    1996-01-01

    1992 ASCAN TRAINING --- Astronaut candidate Koichi Wakata prepares to jump off a box during a parachute landing demonstration at Vance Air Force Base. This portion of the training is designed to familiarize the trainees with the proper way to hit the ground following a parachute jump. Looking on are astronaut candidates Michael L. Gernhardt (left) and Andrew W. S. Thomas (second left), along with a United States Air Force (USAF) instructor. Wakata, representing Japan's National Space Development Agency (NASDA), is one of seven international mission specialist candidates who joined 19 United States astronaut candidates, including Gernhardt and Thomas, for the three-day parachute/survival training school at the Oklahoma Base.EDITORS NOTE: Since this photograph was taken, Gernhardt, Wakata and Thomas have been named as mission specialists for the STS-69, STS-72 and STS-77 missions, respectively.

  3. An evaluation of composite propulsion for single-stage-to-orbit vehicles designed for horizontal take-off

    NASA Technical Reports Server (NTRS)

    Martin, J. A.

    1977-01-01

    Composite propulsion was analyzed for single-stage-to-orbit vehicles designed for horizontal take-off. Trajectory, geometric, and mass analyses were performed to establish the orbital payload capability of six engines. The results indicated that none of the engines performed adequately to deliver payloads to orbit as analyzed. The single-stage turbine and oxidizer-rich gas generator resulted in a low engine specific impulse, and the performance increment of the ejector subsystem was less than that of a separate rocket system with a high combustion pressure. There was a benefit from incorporating a fan into the engine, and removal of the fan from the airstream during the ramjet mode increased the orbital payload capability.

  4. Evaluation of a linear washout for simulator motion cue presentation during landing approach

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

    The comparison of a fixed-base versus a five-degree-of-freedom motion base simulation of a 737 conventional take-off and landing (CTOL) aircraft performing instrument landing system (ILS) landing approaches was used to evaluate a linear motion washout technique. The fact that the pilots felt that the addition of motion increased the pilot workload and this increase was not reflected in the objective data results, indicates that motion cues, as presented, are not a contributing factor to root-mean-square (rms) performance during the landing approach task. Subjective results from standard maneuvering about straight-and-level flight for specific motion cue evaluation revealed that the longitudinal channels (pitch and surge) possibly the yaw channel produce acceptable motions. The roll cue representation, involving both roll and sway channels, was found to be inadequate for large roll inputs, as used for example, in turn entries.

  5. 14 CFR 27.75 - Landing.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Landing. 27.75 Section 27.75 Aeronautics... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Performance § 27.75 Landing. (a) The rotorcraft must be able to... applicant; (2) The approach and landing made with— (i) Power off, for single engine rotorcraft and entered...

  6. 14 CFR 27.75 - Landing.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Landing. 27.75 Section 27.75 Aeronautics... STANDARDS: NORMAL CATEGORY ROTORCRAFT Flight Performance § 27.75 Landing. (a) The rotorcraft must be able to... applicant; (2) The approach and landing made with— (i) Power off, for single engine rotorcraft and entered...

  7. No perfect tools: trade-offs of sustainability principles and user requirements in designing support tools for land-use decisions between greenfields and brownfields.

    PubMed

    Bartke, Stephan; Schwarze, Reimund

    2015-04-15

    The EU Soil Thematic Strategy calls for the application of sustainability concepts and methods as part of an integrated policy to prevent soil degradation and to increase the re-use of brownfields. Although certain general principles have been proposed for the evaluation of sustainable development, the practical application of sustainability assessment tools (SATs) is contingent on the actual requirements of tool users, e.g. planners or investors, to pick up such instruments in actual decision making. We examine the normative sustainability principles that need to be taken into account in order to make sound land-use decisions between new development on greenfield sites and the regeneration of brownfields - and relate these principles to empirically observed user requirements and the properties of available SATs. In this way we provide an overview of approaches to sustainability assessment. Three stylized approaches, represented in each case by a typical tool selected from the literature, are presented and contrasted with (1) the norm-oriented Bellagio sustainability principles and (2) the requirements of three different stakeholder groups: decision makers, scientists/experts and representatives of the general public. The paper disentangles some of the inevitable trade-offs involved in seeking to implement sustainable land-use planning, i.e. between norm orientation and holism, broad participation and effective communication. It concludes with the controversial assessment that there are no perfect tools and that to be meaningful the user requirements of decision makers must take precedence over those of other interest groups in the design of SATs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. The course correction implementation of the inertial navigation system based on the information from the aircraft satellite navigation system before take-off

    NASA Astrophysics Data System (ADS)

    Markelov, V.; Shukalov, A.; Zharinov, I.; Kostishin, M.; Kniga, I.

    2016-04-01

    The use of the correction course option before aircraft take-off after inertial navigation system (INS) inaccurate alignment based on the platform attitude-and-heading reference system in azimuth is considered in the paper. A course correction is performed based on the track angle defined by the information received from the satellite navigation system (SNS). The course correction includes a calculated track error definition during ground taxiing along straight sections before take-off with its input in the onboard digital computational system like amendment for using in the current flight. The track error calculation is performed by the statistical evaluation of the track angle comparison defined by the SNS information with the current course measured by INS for a given number of measurements on the realizable time interval. The course correction testing results and recommendation application are given in the paper. The course correction based on the information from SNS can be used for improving accuracy characteristics for determining an aircraft path after making accelerated INS preparation concerning inaccurate initial azimuth alignment.

  9. Passive imaging based multi-cue hazard detection spacecraft safe landing

    NASA Technical Reports Server (NTRS)

    Huertas, Andres; Cheng, Yang; Madison, Richard

    2006-01-01

    Accurate assessment of potentially damaging ground hazards during the spacecraft EDL (Entry, Descent and Landing) phase is crucial to insure a high probability of safe landing. A lander that encounters a large rock, falls off a cliff, or tips over on a steep slope can sustain mission ending damage. Guided entry is expected to shrink landing ellipses from 100-300 km to -10 km radius for the second generation landers as early as 2009. Regardless of size and location, however, landing ellipses will almost always contain hazards such as craters, discontinuities, steep slopes, and large rocks. It is estimated that an MSL (Mars Science Laboratory)-sized lander should detect and avoid 16- 150m diameter craters, vertical drops similar to the edges of 16m or 3.75m diameter crater, for high and low altitude HAD (Hazard Detection and Avoidance) respectively. It should also be able to detect slopes 20' or steeper, and rocks 0.75m or taller. In this paper we will present a passive imaging based, multi-cue hazard detection and avoidance (HDA) system suitable for Martian and other lander missions. This is the first passively imaged HDA system that seamlessly integrates multiple algorithm-crater detection, slope estimation, rock detection and texture analysis, and multicues- crater morphology, rock distribution, to detect these hazards in real time.

  10. Monitoring land subsidence in Sacramento Valley, California, using GPS

    USGS Publications Warehouse

    Blodgett, J.C.; Ikehara, M.E.; Williams, Gary E.

    1990-01-01

    Land subsidence measurement is usually based on a comparison of bench-mark elevations surveyed at different times. These bench marks, established for mapping or the national vertical control network, are not necessarily suitable for measuring land subsidence. Also, many bench marks have been destroyed or are unstable. Conventional releveling of the study area would be costly and would require several years to complete. Differences of as much as 3.9 ft between recent leveling and published bench-mark elevations have been documented at seven locations in the Sacramento Valley. Estimates of land subsidence less than about 0.3 ft are questionable because elevation data are based on leveling and adjustment procedures that occured over many years. A new vertical control network based on the Global Positioning System (GPS) provides highly accurate vertical control data at relatively low costs, and the survey points can be placed where needed to obtain adequate areal coverage of the area affected by land subsidence.

  11. Wet-dry seasonal and vertical geochemical variations in soil water and their driving forces under different land covers in southwest China karst

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Hu, Bill X.; Wu, Chuanhao; Xu, Kai

    2017-04-01

    Karst aquifers supply drinking water for 25% of the world's population, and they are, however, vulnerable to climate change. Bimonthly hydrochemical data in karst soil water samples from July 2010 to July 2011 were obtained to reveal the seasonal and vertical geochemical variations in soil water under five vegetation types in Qingmuguan, a small karst catchment in southwest China. Soil water chemistry was dominated by Ca2+, HCO3-, and SO42- because of the dissolution of limestone, dolomite, and gypsum minerals in the strata. The predominant hydrochemical types in soil water were Ca2+-HCO3-, Ca2+-SO42-, and mixed Ca2+-HCO3-SO42-. Ca2+ and HCO3- concentrations ranked in the following order: shrub land > dry land > afforestation farmland > bamboo land > grassland. In warm and wet seasons, the main ion concentrations in soil water from grasslands were low. Na+, K+, Ca2+, Mg2+, HCO3-, SO42-, and Cl- concentrations in soil water from other lands were high. An opposite trend was observed in cold and dry seasons. Marked seasonal variations were observed in Ca2+, HCO3-, and NO3- in soil water from dry land. The main ion concentrations in soil water from bamboo lands decreased as soil depth increased. By contrast, the chemistry of soil water from other lands increased as soil depth increased. Their ions were accumulated in depth. A consistent high and low variation between the main ions in soil water and the contents of carbonate and CO2 was found in the soil. Hydrochemical changes in soil water were regulated by the effects of dilution and soil CO2.

  12. Large-scale Vertical Motions, Intensity Change and Precipitation Associated with Land falling Hurricane Katrina over the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Reddy, S. R.; Kwembe, T.; Zhang, Z.

    2016-12-01

    We investigated the possible relationship between the large- scale heat fluxes and intensity change associated with the landfall of Hurricane Katrina. After reaching the category 5 intensity on August 28th , 2005 over the central Gulf of Mexico, Katrina weekend to category 3 before making landfall (August 29th , 2005) on the Louisiana coast with the maximum sustained winds of over 110 knots. We also examined the vertical motions associated with the intensity change of the hurricane. The data for Convective Available Potential Energy for water vapor (CAPE), sea level pressure and wind speed were obtained from the Atmospheric Soundings, and NOAA National Hurricane Center (NHC), respectively for the period August 24 to September 3, 2005. We also computed vertical motions using CAPE values. The study showed that the large-scale heat fluxes reached maximum (7960W/m2) with the central pressure 905mb. The Convective Available Potential Energy and the vertical motions peaked 3-5 days before landfall. The large atmospheric vertical motions associated with the land falling hurricane Katrina produced severe weather including thunderstorm, tornadoes, storm surge and floods Numerical model (WRF/ARW) with data assimilations have been used for this research to investigate the model's performances on hurricane tracks and intensities associated with the hurricane Katrina, which began to strengthen until reaching Category 5 on 28 August 2005. The model was run on a doubly nested domain centered over the central Gulf of Mexico, with grid spacing of 90 km and 30 km for 6 hr periods, from August 28th to August 30th. The model output was compared with the observations and is capable of simulating the surface features, intensity change and track associated with hurricane Katrina.

  13. Astronaut Risk Levels During Crew Module (CM) Land Landing

    NASA Technical Reports Server (NTRS)

    Lawrence, Charles; Carney, Kelly S.; Littell, Justin

    2007-01-01

    The NASA Engineering Safety Center (NESC) is investigating the merits of water and land landings for the crew exploration vehicle (CEV). The merits of these two options are being studied in terms of cost and risk to the astronauts, vehicle, support personnel, and general public. The objective of the present work is to determine the astronaut dynamic response index (DRI), which measures injury risks. Risks are determined for a range of vertical and horizontal landing velocities. A structural model of the crew module (CM) is developed and computational simulations are performed using a transient dynamic simulation analysis code (LS-DYNA) to determine acceleration profiles. Landing acceleration profiles are input in a human factors model that determines astronaut risk levels. Details of the modeling approach, the resulting accelerations, and astronaut risk levels are provided.

  14. Unmanned air vehicle: autonomous takeoff and landing

    NASA Astrophysics Data System (ADS)

    Lim, K. L.; Gitano-Briggs, Horizon Walker

    2010-03-01

    UAVs are increasing in popularity and sophistication due to the demonstrated performance which cannot be attained by manned aircraft1. These developments have been made possible by development of sensors, instrumentation, telemetry and controls during the last few decades. UAVs are now common in areas such as aerial observation and as communication relays3. Most UAVs, however, are still flown by a human pilot via remote control from a ground station. Even the existing autonomous UAVs often require a human pilot to handle the most difficult tasks of take off and landing2 (TOL). This is mainly because the navigation of the airplane requires observation, constant situational assessment and hours of experience from the pilot himself4. Therefore, an autonomous takeoff and landing system (TLS) for UAVs using a few practical design rules with various sensors, instrumentation, etc has been developed. This paper details the design and modeling of the UAV TLS. The model indicates that the UAV's TLS shows promising stability.

  15. Unmanned air vehicle: autonomous takeoff and landing

    NASA Astrophysics Data System (ADS)

    Lim, K. L.; Gitano-Briggs, Horizon Walker

    2009-12-01

    UAVs are increasing in popularity and sophistication due to the demonstrated performance which cannot be attained by manned aircraft1. These developments have been made possible by development of sensors, instrumentation, telemetry and controls during the last few decades. UAVs are now common in areas such as aerial observation and as communication relays3. Most UAVs, however, are still flown by a human pilot via remote control from a ground station. Even the existing autonomous UAVs often require a human pilot to handle the most difficult tasks of take off and landing2 (TOL). This is mainly because the navigation of the airplane requires observation, constant situational assessment and hours of experience from the pilot himself4. Therefore, an autonomous takeoff and landing system (TLS) for UAVs using a few practical design rules with various sensors, instrumentation, etc has been developed. This paper details the design and modeling of the UAV TLS. The model indicates that the UAV's TLS shows promising stability.

  16. Large off-nadir scan angle of airborne LiDAR can severely affect the estimates of forest structure metrics

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Skidmore, Andrew K.; Jones, Simon; Wang, Tiejun; Heurich, Marco; Zhu, Xi; Shi, Yifang

    2018-02-01

    Gap fraction (Pgap) and vertical gap fraction profile (vertical Pgap profile) are important forest structural metrics. Accurate estimation of Pgap and vertical Pgap profile is therefore critical for many ecological applications, including leaf area index (LAI) mapping, LAI profile estimation and wildlife habitat modelling. Although many studies estimated Pgap and vertical Pgap profile from airborne LiDAR data, the scan angle was often overlooked and a nadir view assumed. However, the scan angle can be off-nadir and highly variable in the same flight strip or across different flight strips. In this research, the impact of off-nadir scan angle on Pgap and vertical Pgap profile was evaluated, for several forest types. Airborne LiDAR data from nadir (0°∼7°), small off-nadir (7°∼23°), and large off-nadir (23°∼38°) directions were used to calculate both Pgap and vertical Pgap profile. Digital hemispherical photographs (DHP) acquired during fieldwork were used as references for validation. Our results show that angular Pgap from airborne LiDAR correlates well with angular Pgap from DHP (R2 = 0.74, 0.87, and 0.67 for nadir, small off-nadir and large off-nadir direction). But underestimation of Pgap from LiDAR amplifies at large off-nadir scan angle. By comparing Pgap and vertical Pgap profiles retrieved from different directions, it is shown that scan angle impact on Pgap and vertical Pgap profile differs amongst different forest types. The difference is likely to be caused by different leaf angle distribution and canopy architecture in these forest types. Statistical results demonstrate that the scan angle impact is more severe for plots with discontinuous or sparse canopies. These include coniferous plots, and deciduous or mixed plots with between-crown gaps. In these discontinuous plots, Pgap and vertical Pgap profiles are maximum when observed from nadir direction, and then rapidly decrease with increasing scan angle. The results of this research have many

  17. An Impulse-Momentum Method for Calculating Landing-Gear Contact Conditions in Eccentric Landings

    NASA Technical Reports Server (NTRS)

    Yntema, Robert T; Milwitzky, Benjamin

    1952-01-01

    An impulse-momentum method for determining impact conditions for landing gears in eccentric landings is presented. The analysis is primarily concerned with the determination of contact velocities for impacts subsequent to initial touchdown in eccentric landings and with the determination of the effective mass acting on each landing gear. These parameters determine the energy-absorption requirements for the landing gear and, in conjunction with the particular characteristics of the landing gear, govern the magnitude of the ground loads. Changes in airplane angular and linear velocities and the magnitude of landing-gear vertical, drag, and side impulses resulting from a landing impact are determined by means of impulse-momentum relationships without the necessity for considering detailed force-time variations. The effective mass acting on each gear is also determined from the calculated landing-gear impulses. General equations applicable to any type of eccentric landing are written and solutions are obtained for the particular cases of an impact on one gear, a simultaneous impact on any two gears, and a symmetrical impact. In addition a solution is presented for a simplified two-degree-of-freedom system which allows rapid qualitative evaluation of the effects of certain principal parameters. The general analysis permits evaluation of the importance of such initial conditions at ground contact as vertical, horizontal, and side drift velocities, wing lift, roll and pitch angles, and rolling and pitching velocities, as well as the effects of such factors as landing gear location, airplane inertia, landing-gear length, energy-absorption efficiency, and wheel angular inertia on the severity of landing impacts. -A brief supplementary study which permits a limited evaluation of variable aerodynamic effects neglected in the analysis is presented in the appendix. Application of the analysis indicates that landing-gear impacts in eccentric landings can be appreciably more

  18. 14 CFR 29.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

  19. 14 CFR 29.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

  20. 14 CFR 27.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

  1. 14 CFR 27.485 - Lateral drift landing conditions.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...— (1) Side loads combined with one-half of the maximum ground reactions obtained in the level landing..., side loads of 0.8 times the vertical reaction acting inward on one side, and 0.6 times the vertical reaction acting outward on the other side, all combined with the vertical loads specified in paragraph (a...

  2. Two-stage fixed-bed gasifier with selectable middle gas off-take point

    DOEpatents

    Strickland, Larry D.; Bissett, Larry A.

    1992-01-01

    A two-stage fixed bed coal gasifier wherein an annular region is in registry with a gasification zone underlying a devolatilization zone for extracting a side stream of high temperature substantially tar-free gas from the gasifier. A vertically displaceable skirt means is positioned within the gasifier to define the lower portion of the annular region so that vertical displacement of the skirt means positions the inlet into the annular region in a selected location within or in close proximity to the gasification zone for providing a positive control over the composition of the side stream gas.

  3. Unifying Speed-Accuracy Trade-Off and Cost-Benefit Trade-Off in Human Reaching Movements.

    PubMed

    Peternel, Luka; Sigaud, Olivier; Babič, Jan

    2017-01-01

    Two basic trade-offs interact while our brain decides how to move our body. First, with the cost-benefit trade-off, the brain trades between the importance of moving faster toward a target that is more rewarding and the increased muscular cost resulting from a faster movement. Second, with the speed-accuracy trade-off, the brain trades between how accurate the movement needs to be and the time it takes to achieve such accuracy. So far, these two trade-offs have been well studied in isolation, despite their obvious interdependence. To overcome this limitation, we propose a new model that is able to simultaneously account for both trade-offs. The model assumes that the central nervous system maximizes the expected utility resulting from the potential reward and the cost over the repetition of many movements, taking into account the probability to miss the target. The resulting model is able to account for both the speed-accuracy and the cost-benefit trade-offs. To validate the proposed hypothesis, we confront the properties of the computational model to data from an experimental study where subjects have to reach for targets by performing arm movements in a horizontal plane. The results qualitatively show that the proposed model successfully accounts for both cost-benefit and speed-accuracy trade-offs.

  4. Verticality perception during and after galvanic vestibular stimulation.

    PubMed

    Volkening, Katharina; Bergmann, Jeannine; Keller, Ingo; Wuehr, Max; Müller, Friedemann; Jahn, Klaus

    2014-10-03

    The human brain constructs verticality perception by integrating vestibular, somatosensory, and visual information. Here we investigated whether galvanic vestibular stimulation (GVS) has an effect on verticality perception both during and after application, by assessing the subjective verticals (visual, haptic and postural) in healthy subjects at those times. During stimulation the subjective visual vertical and the subjective haptic vertical shifted towards the anode, whereas this shift was reversed towards the cathode in all modalities once stimulation was turned off. Overall, the effects were strongest for the haptic modality. Additional investigation of the time course of GVS-induced changes in the haptic vertical revealed that anodal shifts persisted for the entire 20-min stimulation interval in the majority of subjects. Aftereffects exhibited different types of decay, with a preponderance for an exponential decay. The existence of such reverse effects after stimulation could have implications for GVS-based therapy. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. Models for estimating runway landing capacity with Microwave Landing System (MLS)

    NASA Technical Reports Server (NTRS)

    Tosic, V.; Horonjeff, R.

    1975-01-01

    A model is developed which is capable of computing the ultimate landing runway capacity, under ILS and MLS conditions, when aircraft population characteristics and air traffic control separation rules are given. This model can be applied in situations when only a horizontal separation between aircraft approaching a runway is allowed, as well as when both vertical and horizontal separations are possible. It is assumed that the system is free of errors, that is that aircraft arrive at specified points along the prescribed flight path precisely when the controllers intend for them to arrive at these points. Although in the real world there is no such thing as an error-free system, the assumption is adequate for a qualitative comparison of MLS with ILS. Results suggest that an increase in runway landing capacity, caused by introducing the MLS multiple approach paths, is to be expected only when an aircraft population consists of aircraft with significantly differing approach speeds and particularly in situations when vertical separation can be applied. Vertical separation can only be applied if one of the types of aircraft in the mix has a very steep descent angle.

  6. Critical engine system design characteristics for SSTO vehicles

    NASA Astrophysics Data System (ADS)

    Fanciullo, Thomas J.; Judd, D. C.; Obrien, C. J.

    1992-02-01

    Engine system design characteristics are summarized for typical vertical take-off and landing (VTOL) and vertical take-off and horizontal landing (VTHL) Strategic Defense Initiative Organization (SDIO) single stage to orbit (SSTO) vehicles utilizing plug nozzle configurations. Power cycle selection trades involved the unique modular platelet engine (MPE) with the use of (1) LO2 and LH2 at fixed and variable mixture ratios, (2) LO2 and propane or RP-1, and (3) dual fuels (LO2 with LH2 and C3H8). The number of thrust cells and modules were optimized. Dual chamber bell and a cluster of conventional bell nozzle configurations were examined for comparison with the plug configuration. Thrust modulation (throttling) was selected for thrust vector control. Installed thrust ratings were established to provide an additional 20 percent overthrust capability for engine out operation. Turbopumps were designed to operate at subcritical speeds to facilitate a wide range of throttling and long life. A unique dual spool arrangement with hydrostatic bearings was selected for the LH2 turbopump. Controls and health monitoring with expert systems for diagnostics are critical subsystems to ensure minimum maintenance and supportability for a less than seven day turnaround. The use of an idle mode start, in conjunction with automated health condition monitoring, allows the rocket propulsion system to operate reliably in the manner of present day aircraft propulsion.

  7. Off-Highway Transportation-Related Fuel Use

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

    Davis, S.C.

    2004-05-08

    The transportation sector includes many subcategories--for example, on-highway, off-highway, and non-highway. Use of fuel for off-highway purposes is not well documented, nor is the number of off-highway vehicles. The number of and fuel usage for on-highway and aviation, marine, and rail categories are much better documented than for off-highway land-based use. Several sources document off-highway fuel use under specific conditions--such as use by application (e.g., recreation) or by fuel type (e.g., gasoline). There is, however, no single source that documents the total fuel used off-highway and the number of vehicles that use the fuel. This report estimates the fuel usagemore » and number of vehicles/equipment for the off-highway category. No new data have been collected nor new models developed to estimate the off-highway data--this study is limited in scope to using data that already exist. In this report, unless they are being quoted from a source that uses different terminology, the terms are used as listed below. (1) ''On-highway/on-road'' includes land-based transport used on the highway system or other paved roadways. (2) ''Off-highway/off-road'' includes land-based transport not using the highway system or other paved roadways. (3) ''Non-highway/non-road'' includes other modes not traveling on highways such as aviation, marine, and rail. It should be noted that the term ''transportation'' as used in this study is not typical. Generally, ''transportation'' is understood to mean the movement of people or goods from one point to another. Some of the off-highway equipment included in this study doesn't transport either people or goods, but it has utility in movement (e.g., a forklift or a lawn mower). Along these lines, a chain saw also has utility in movement, but it cannot transport itself (i.e., it must be carried) because it does not have wheels. Therefore, to estimate the transportation-related fuel used off-highway, transportation equipment is defined

  8. Towards a Spatial Understanding of Trade-Offs in Sustainable Development: A Meso-Scale Analysis of the Nexus between Land Use, Poverty, and Environment in the Lao PDR.

    PubMed

    Messerli, Peter; Bader, Christoph; Hett, Cornelia; Epprecht, Michael; Heinimann, Andreas

    2015-01-01

    In land systems, equitably managing trade-offs between planetary boundaries and human development needs represents a grand challenge in sustainability oriented initiatives. Informing such initiatives requires knowledge about the nexus between land use, poverty, and environment. This paper presents results from Lao PDR, where we combined nationwide spatial data on land use types and the environmental state of landscapes with village-level poverty indicators. Our analysis reveals two general but contrasting trends. First, landscapes with paddy or permanent agriculture allow a greater number of people to live in less poverty but come at the price of a decrease in natural vegetation cover. Second, people practising extensive swidden agriculture and living in intact environments are often better off than people in degraded paddy or permanent agriculture. As poverty rates within different landscape types vary more than between landscape types, we cannot stipulate a land use-poverty-environment nexus. However, the distinct spatial patterns or configurations of these rates point to other important factors at play. Drawing on ethnicity as a proximate factor for endogenous development potentials and accessibility as a proximate factor for external influences, we further explore these linkages. Ethnicity is strongly related to poverty in all land use types almost independently of accessibility, implying that social distance outweighs geographic or physical distance. In turn, accessibility, almost a precondition for poverty alleviation, is mainly beneficial to ethnic majority groups and people living in paddy or permanent agriculture. These groups are able to translate improved accessibility into poverty alleviation. Our results show that the concurrence of external influences with local-highly contextual-development potentials is key to shaping outcomes of the land use-poverty-environment nexus. By addressing such leverage points, these findings help guide more effective

  9. Towards a Spatial Understanding of Trade-Offs in Sustainable Development: A Meso-Scale Analysis of the Nexus between Land Use, Poverty, and Environment in the Lao PDR

    PubMed Central

    Messerli, Peter; Bader, Christoph; Hett, Cornelia; Epprecht, Michael; Heinimann, Andreas

    2015-01-01

    In land systems, equitably managing trade-offs between planetary boundaries and human development needs represents a grand challenge in sustainability oriented initiatives. Informing such initiatives requires knowledge about the nexus between land use, poverty, and environment. This paper presents results from Lao PDR, where we combined nationwide spatial data on land use types and the environmental state of landscapes with village-level poverty indicators. Our analysis reveals two general but contrasting trends. First, landscapes with paddy or permanent agriculture allow a greater number of people to live in less poverty but come at the price of a decrease in natural vegetation cover. Second, people practising extensive swidden agriculture and living in intact environments are often better off than people in degraded paddy or permanent agriculture. As poverty rates within different landscape types vary more than between landscape types, we cannot stipulate a land use–poverty–environment nexus. However, the distinct spatial patterns or configurations of these rates point to other important factors at play. Drawing on ethnicity as a proximate factor for endogenous development potentials and accessibility as a proximate factor for external influences, we further explore these linkages. Ethnicity is strongly related to poverty in all land use types almost independently of accessibility, implying that social distance outweighs geographic or physical distance. In turn, accessibility, almost a precondition for poverty alleviation, is mainly beneficial to ethnic majority groups and people living in paddy or permanent agriculture. These groups are able to translate improved accessibility into poverty alleviation. Our results show that the concurrence of external influences with local—highly contextual—development potentials is key to shaping outcomes of the land use–poverty–environment nexus. By addressing such leverage points, these findings help guide more

  10. Preliminary design of a supersonic Short Takeoff and Vertical Landing (STOVL) fighter aircraft

    NASA Technical Reports Server (NTRS)

    Cox, Brian; Borchers, Paul; Gomer, Charlie; Henderson, Dean; Jacobs, Tavis; Lawson, Todd; Peterson, Eric; Ross, Tweed, III; Bellmard, Larry

    1990-01-01

    The preliminary design study of a supersonic Short Takeoff and Vertical Landing (STOVL) fighter is presented. A brief historical survey of powered lift vehicles was presented, followed by a technology assessment of the latest supersonic STOVL engine cycles under consideration by industry and government in the U.S. and UK. A survey of operational fighter/attack aircraft and the modern battlefield scenario were completed to develop, respectively, the performance requirements and mission profiles for the study. Three configurations were initially investigated with the following engine cycles: a hybrid fan vectored thrust cycle, a lift+lift/cruise cycle, and a mixed flow vectored thrust cycle. The lift+lift/cruise aircraft configuration was selected for detailed design work which consisted of: (1) a material selection and structural layout, including engine removal considerations, (2) an aircraft systems layout, (3) a weapons integration model showing the internal weapons bay mechanism, (4) inlet and nozzle integration, (5) an aircraft suckdown prediction, (6) an aircraft stability and control analysis, including a takeoff, hover, and transition control analysis, (7) a performance and mission capability study, and (8) a life cycle cost analysis. A supersonic fighter aircraft with STOVL capability with the lift+lift/cruise engine cycle seems a viable option for the next generation fighter.

  11. Analysis of Landing-Gear Behavior

    NASA Technical Reports Server (NTRS)

    Milwitzky, Benjamin; Cook, Francis E

    1953-01-01

    This report presents a theoretical study of the behavior of the conventional type of oleo-pneumatic landing gear during the process of landing impact. The basic analysis is presented in a general form and treats the motions of the landing gear prior to and subsequent to the beginning of shock-strut deflection. The applicability of the analysis to actual landing gears has been investigated for the particular case of a vertical landing gear in the absence of drag loads by comparing calculated results with experimental drop-test data for impacts with and without tire bottoming. The calculated behavior of the landing gear was found to be in good agreement with the drop-test data.

  12. Vertical ground reaction force in stationary running in water and on land: A study with a wide range of cadences.

    PubMed

    de Brito Fontana, Heiliane; Ruschel, Caroline; Dell'Antonio, Elisa; Haupenthal, Alessandro; Pereira, Gustavo Soares; Roesler, Helio

    2018-04-01

    The aim of this study was to analyze the effect of cadence, immersion level as well as body density on the vertical component (Fy max ) of ground reaction force (GRF) during stationary running (SR). In a controlled, laboratory study, thirty-two subjects ran at a wide range of cadences (85-210 steps/min) in water, immersed to the hip and to the chest, and on dry land. Fy max. was verified by a waterproof force measurement system and predicted based on a statistical model including cadence, immersion ratio and body density. The effect of cadence was shown to depend on the environment: while Fy max increases linearly with increasing cadence on land; in water, Fy max reaches a plateau at both hip and chest immersions. All factors analyzed, cadence, immersion level and body density affected Fy max significantly, with immersion (aquatic × land environment) showing the greatest effect. In water, different cadences may lead to bigger changes in Fy max than the changes obtained by moving subjects from hip to chest immersion. A regression model able to predict 69% of Fy max variability in water was proposed and validated. Cadence, Immersion and body density affect Fy max in a significant and non-independent way. Besides a model of potential use in the prescription of stationary running in water, our analysis provides insights into the different responses of GRF to changes in exercise parameters between land and aquatic environment. Copyright © 2018 Elsevier B.V. All rights reserved.

  13. 43 CFR 420.22 - Criteria for off-road vehicle areas.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 43 Public Lands: Interior 1 2010-10-01 2010-10-01 false Criteria for off-road vehicle areas. 420..., DEPARTMENT OF THE INTERIOR OFF-ROAD VEHICLE USE Designated Areas and Permitted Events § 420.22 Criteria for off-road vehicle areas. (a) Areas and trails to be opened to off-road vehicle use shall be located: (1...

  14. 43 CFR 420.22 - Criteria for off-road vehicle areas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Criteria for off-road vehicle areas. 420..., DEPARTMENT OF THE INTERIOR OFF-ROAD VEHICLE USE Designated Areas and Permitted Events § 420.22 Criteria for off-road vehicle areas. (a) Areas and trails to be opened to off-road vehicle use shall be located: (1...

  15. Crew Exploration Vehicle (CEV) Water Landing Simulation

    NASA Technical Reports Server (NTRS)

    Littell, Justin D.; Lawrence, Charles; Carney, Kelly S.

    2007-01-01

    Crew Exploration Vehicle (CEV) water splashdowns were simulated in order to find maximum acceleration loads on the astronauts and spacecraft under various landing conditions. The acceleration loads were used in a Dynamic Risk Index (DRI) program to find the potential risk for injury posed on the astronauts for a range of landing conditions. The DRI results showed that greater risks for injury occurred for two landing conditions; when the vertical velocity was large and the contact angle between the spacecraft and the water impact surface was zero, and when the spacecraft was in a toe down configuration and both the vertical and horizontal landing velocities were large. Rollover was also predicted to occur for cases where there is high horizontal velocity and low contact angles in a toe up configuration, and cases where there was a high horizontal velocity with high contact angles in a toe down configuration.

  16. Lousy mums: patterns of vertical transmission of an amphibious louse.

    PubMed

    Leonardi, M S; Crespo, E A; Raga, J A; Aznar, F J

    2013-09-01

    In this study, we document patterns of vertical transmission of the amphibious louse Antarctophthirus microchir (Echinophthiriidae) in pups of South American sea lion, Otaria flavescens, from Patagonia. Vertical transmission is fundamental for the long-term stability of A. microchir populations because only pups stay long enough (1 month) on land for the louse to reproduce. A total of 72 pups ≤7 days old from a single rookery were captured and examined for lice. Infection parameters and population structure of A. microchir did not differ among pups collected at the beginning, middle, and end of the reproductive season, suggesting that patterns of early vertical transmission are not affected by the increase of rookery size during this period. Over 60% of 1-day-old pups were infected with A. microchir, and recruitment increased in pups up to 3 days old and then leveled off. In 1-day-old pups, significantly more adults than nymphs were found, but the pattern was reversed in older pups. The number of first-stage nymphs was significantly smaller than that of second- and third-stage nymphs, as it was the number of males vs. females, particularly in 1-day-old pups. Three non-exclusive hypotheses could account for these patterns, i.e., recruitment merely reflects the population structure of A. microchir is cows; the relative ability of lice to pass from cows onto pups increases in advanced instars; and/or natural selection favors transmission of adults, especially females, because they accrue greater fitness. The importance of latter hypothesis should not be underestimated in a species with a tight reproductive schedule.

  17. An eco-hydrological modeling framework for assessing trade-offs among ecosystem services in response to alternative land use scenarios

    NASA Astrophysics Data System (ADS)

    Mckane, R.; Abdelnour, A. G.; Brookes, A.; Djang, K.; Stieglitz, M.; Pan, F.; Bolte, J.; Papenfus, M.; Burdick, C.

    2012-12-01

    Scientists, policymakers, community planners and others have discussed ecosystem services for decades, however, society is still in the early stages of developing methodologies to quantify and value the services that ecosystems provide. For example, the U.S. Environmental Protection Agency recently established the Sustainable and Healthy Communities Research Program to develop such methodologies, so that natural capital can be better accounted for in decisions that affect the supply of the ecosystem goods and services upon which human well-being depends. Essential to this goal are highly integrated models that can be used to define policy and management strategies for entire ecosystems, not simply individual components of the ecosystem. We developed the VELMA (Visualizing Ecosystems for Land Management Assessments) eco-hydrologic modeling framework to help address this emerging risk assessment objective. Here we describe a proof-of-concept application of VELMA to the H.J. Andrews Experimental Forest, a forested 64 km2 basin and Long Term Ecological Research site in the western Cascade Range of Oregon, USA. VELMA is a spatially-distributed eco-hydrologic model that links a land surface hydrologic model with a terrestrial biogeochemistry model for simulating the integrated responses of vegetation, soil, and water resources to interacting stressors. We used the model to simulate the effects of three different land use scenarios (100% old-growth, 100% clearcut harvest, and present-day land cover consisting of 45% old-growth and 55% harvested) on trade-offs among five ecosystem services: timber production, carbon sequestration, greenhouse gas regulation, water quantity, and water quality. Compared to the old-growth simulation, over a 60-yr period the clearcut simulation reduced total ecosystem carbon stocks (-40%), and initially increased total stream discharge (+28%), stream nitrogen export (>300%), and total CO2 and N2O radiative forcing (>200%). The simulation for

  18. 43 CFR 420.21 - Procedure for designating areas for off-road vehicle use.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... cultural or historic resources of particular areas or trails of the public lands, he shall immediately... 43 Public Lands: Interior 1 2011-10-01 2011-10-01 false Procedure for designating areas for off... BUREAU OF RECLAMATION, DEPARTMENT OF THE INTERIOR OFF-ROAD VEHICLE USE Designated Areas and Permitted...

  19. Binocular Coordination of the Human Vestibulo-Ocular Reflex during Off-axis Pitch Rotation

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Reschke, M. F.; Kaufman, G. D.; Black, F. O.; Paloski, W. H.

    2006-01-01

    Head movements in the sagittal pitch plane typically involve off-axis rotation requiring both vertical and horizontal vergence ocular reflexes to compensate for angular and translational motion relative to visual targets of interest. The purpose of this study was to compare passive pitch VOR responses during rotation about an Earth-vertical axis (canal only cues) with off-axis rotation (canal and otolith cues). Methods. Eleven human subjects were oscillated sinusoidally at 0.13, 0.3 and 0.56 Hz while lying left-side down with the interaural axis either aligned with the axis of rotation or offset by 50 cm. In a second set of measurements, twelve subjects were also tested during sinusoidally varying centrifugation over the same frequency range. The modulation of vertical and horizontal vergence ocular responses was measured with a binocular videography system. Results. Off-axis pitch rotation enhanced the vertical VOR at lower frequencies and enhanced the vergence VOR at higher frequencies. During sinusoidally varying centrifugation, the opposite trend was observed for vergence, with both vertical and vergence vestibulo-ocular reflexes being suppressed at the highest frequency. Discussion. These differential effects of off-axis rotation over the 0.13 to 0.56 Hz range are consistent with the hypothesis that otolith-ocular reflexes are segregated in part on the basis of stimulus frequency. At the lower frequencies, tilt otolith-ocular responses compensate for declining canal input. At higher frequencies, translational otolith-ocular reflexes compensate for declining visual contributions to the kinematic demands required for fixating near targets.

  20. Spatial distribution of Salpa thompsoni in the high Antarctic area off Adélie Land, East Antarctica during the austral summer 2008

    NASA Astrophysics Data System (ADS)

    Ono, Atsushi; Moteki, Masato

    2017-06-01

    The salp Salpa thompsoni has the potential to alter the Southern Ocean ecosystem through competition with krill Euphausia superba. Information on the reproductive status of S. thompsoni in the high Southern Ocean is thus essential to understanding salp population growth and predicting changes in the Southern Ocean ecosystem. We carried out stratified and quantitative sampling from the surface to a depth of 2000 m during the austral summer of 2008 to determine the spatial distribution and population structure of S. thompsoni in the Southern Ocean off Adélie Land. We found two salp species, S. thompsoni and Ihlea racovitzai, with the former being dominant. S. thompsoni was distributed north of the continental slope area, while I. racovitzai was observed in the neritic zone. Mature aggregates and solitary specimens of S. thompsoni were found south of the Southern Boundary of the Antarctic Circumpolar Current, suggesting that S. thompsoni is able to complete its life cycle in high Antarctic waters during the austral summer. However, S. thompsoni was sparsely distributed in the continental slope area, and absent south of the Antarctic Slope Front, suggesting that it is less competitive with krill for food in the slope area off Adélie Land, where krill is densely distributed during the austral summer.

  1. Reactor on-off antineutrino measurement with KamLAND

    NASA Astrophysics Data System (ADS)

    Gando, A.; Gando, Y.; Hanakago, H.; Ikeda, H.; Inoue, K.; Ishidoshiro, K.; Ishikawa, H.; Koga, M.; Matsuda, R.; Matsuda, S.; Mitsui, T.; Motoki, D.; Nakamura, K.; Obata, A.; Oki, A.; Oki, Y.; Otani, M.; Shimizu, I.; Shirai, J.; Suzuki, A.; Takemoto, Y.; Tamae, K.; Ueshima, K.; Watanabe, H.; Xu, B. D.; Yamada, S.; Yamauchi, Y.; Yoshida, H.; Kozlov, A.; Yoshida, S.; Piepke, A.; Banks, T. I.; Fujikawa, B. K.; Han, K.; O'Donnell, T.; Berger, B. E.; Learned, J. G.; Matsuno, S.; Sakai, M.; Efremenko, Y.; Karwowski, H. J.; Markoff, D. M.; Tornow, W.; Detwiler, J. A.; Enomoto, S.; Decowski, M. P.

    2013-08-01

    The recent long-term shutdown of Japanese nuclear reactors has resulted in a significantly reduced reactor ν¯e flux at KamLAND. This running condition provides a unique opportunity to confirm and constrain backgrounds for the reactor ν¯e oscillation analysis. The data set also has improved sensitivity for other ν¯e signals, in particular ν¯e’s produced in β-decays from U238 and Th232 within the Earth’s interior, whose energy spectrum overlaps with that of reactor ν¯e’s. Including constraints on θ13 from accelerator and short-baseline reactor neutrino experiments, a combined three-flavor analysis of solar and KamLAND data gives fit values for the oscillation parameters of tan⁡2θ12=0.436-0.025+0.029, Δm212=7.53-0.18+0.18×10-5eV2, and sin⁡2θ13=0.023-0.002+0.002. Assuming a chondritic Th/U mass ratio, we obtain 116-27+28 ν¯e events from U238 and Th232, corresponding to a geo ν¯e flux of 3.4-0.8+0.8×106cm-2s-1 at the KamLAND location. We evaluate various bulk silicate Earth composition models using the observed geo ν¯e rate.

  2. Acute kinematic and kinetic adaptations to wearable resistance during vertical jumping.

    PubMed

    Macadam, Paul; Simperingham, Kim D; Cronin, John B; Couture, Grace; Evison, Chloe

    2017-06-01

    body WR of 3-6% BM without fear of overloading the athletesover and above the landing forces they are typically accustomed too. As a training stimulus it would seem the WR loading provides adequate overload and athletes should focus on velocity of movement to improve power output and jump height i.e. take-off velocity.

  3. Interparameter trade-off quantification and reduction in isotropic-elastic full-waveform inversion: synthetic experiments and Hussar land data set application

    NASA Astrophysics Data System (ADS)

    Pan, Wenyong; Geng, Yu; Innanen, Kristopher A.

    2018-05-01

    The problem of inverting for multiple physical parameters in the subsurface using seismic full-waveform inversion (FWI) is complicated by interparameter trade-off arising from inherent ambiguities between different physical parameters. Parameter resolution is often characterized using scattering radiation patterns, but these neglect some important aspects of interparameter trade-off. More general analysis and mitigation of interparameter trade-off in isotropic-elastic FWI is possible through judiciously chosen multiparameter Hessian matrix-vector products. We show that products of multiparameter Hessian off-diagonal blocks with model perturbation vectors, referred to as interparameter contamination kernels, are central to the approach. We apply the multiparameter Hessian to various vectors designed to provide information regarding the strengths and characteristics of interparameter contamination, both locally and within the whole volume. With numerical experiments, we observe that S-wave velocity perturbations introduce strong contaminations into density and phase-reversed contaminations into P-wave velocity, but themselves experience only limited contaminations from other parameters. Based on these findings, we introduce a novel strategy to mitigate the influence of interparameter trade-off with approximate contamination kernels. Furthermore, we recommend that the local spatial and interparameter trade-off of the inverted models be quantified using extended multiparameter point spread functions (EMPSFs) obtained with pre-conditioned conjugate-gradient algorithm. Compared to traditional point spread functions, the EMPSFs appear to provide more accurate measurements for resolution analysis, by de-blurring the estimations, scaling magnitudes and mitigating interparameter contamination. Approximate eigenvalue volumes constructed with stochastic probing approach are proposed to evaluate the resolution of the inverted models within the whole model. With a synthetic

  4. Design, Development, And Testing of Umbilical System Mechanisms for the X-33 Advanced Technology Demonstrator

    NASA Technical Reports Server (NTRS)

    Littlefield, Alan C.; Melton, Gregory S.

    2000-01-01

    The X-33 Advanced Technology Demonstrator is an un-piloted, vertical take-off, horizontal landing spacecraft. The purpose of the X-33 program is to demonstrate technologies that will dramatically lower the cost of access to space. The rocket-powered X-33 will reach an altitude of up to 100 km and speeds between Mach 13 and 15. Fifteen flight tests are planned, beginning in 2000. Some of the key technologies demonstrated will be the linear aerospike engine, improved thermal protection systems, composite fuel tanks and reduced operational timelines. The X-33 vehicle umbilical connections provide monitoring, power, cooling, purge, and fueling capability during horizontal processing and vertical launch operations. Two "rise-off" umbilicals for the X-33 have been developed, tested, and installed. The X-33 umbilical systems mechanisms incorporate several unique design features to simplify horizontal operations and provide reliable disconnect during launch.

  5. Unconscious-thought effects take place off-line, not on-line.

    PubMed

    Strick, Madelijn; Dijksterhuis, Ap; van Baaren, Rick B

    2010-04-01

    The unconscious-thought effect refers to an improvement in decision making following distraction from the decision context for a period of time. The dominant explanation for this effect is that unconscious processes continue to deal with the problem during the distraction period. Recently, however, some researchers have proposed that unconscious thinkers may be merely recalling a judgment that was formed on-line (i.e., during information acquisition). We present two experiments that rule out the latter interpretation. In the unconscious-thought condition of the first experiment, participants who reported making their decision after unconscious thought made better decisions than those who reported making their decision on-line. In the second experiment, all participants judged the choice alternatives both on-line and off-line. On-line judgments were predictive of off-line judgments only in the immediate-decision condition, but not in the conscious- and unconscious-thought conditions. These results demonstrate that a period of unconscious thought does improve judgments that were formed earlier on-line.

  6. Effect of Afterbody Length and Keel Angle on Minimum Depth of Step for Landing Stability and on Take-Off Stability of a Flying Boat

    NASA Technical Reports Server (NTRS)

    Olson, Roland E; Land, Norman S

    1949-01-01

    Tests were made to fill partly the need for information on the effect of afterbody dimensions on the hydrodynamic stability of a flying boat in smooth water. The dimensions investigated were depth of step, angle of afterbody keel, and length of afterbody. An analysis of the data showed that as either the afterbody length or keel angle was increased an accompanying increase in depth of step was required in order to maintain adequate landing stability. The landing-tests results have been reduced to an empirical formula giving the minimum depth of step in terms of afterbody length and keel angle. This formula is compared with results from other tank tests, and the correlation is fairly good. The formula thus becomes of use in preliminary design.

  7. Surface tension profiles in vertical soap films

    NASA Astrophysics Data System (ADS)

    Adami, N.; Caps, H.

    2015-01-01

    Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements.

  8. Masten Xombie for Testing of JPL Spacecraft-Landing Algorithm

    NASA Image and Video Library

    2013-08-12

    A Xombie technology demonstrator from Masten Space Systems, Mojave, Calif., ascends from its pad at Mojave Air and Space Port on a test for NASA Jet Propulsion Laboratory. The vehicle is a vertical-takeoff, vertical-landing experimental rocket.

  9. Noise generated by a flight weight, air flow control valve in a vertical takeoff and landing aircraft thrust vectoring system

    NASA Technical Reports Server (NTRS)

    Huff, Ronald G.

    1989-01-01

    Tests were conducted in the NASA Lewis Research Center's Powered Lift Facility to experimentally evaluate the noise generated by a flight weight, 12 in. butterfly valve installed in a proposed vertical takeoff and landing thrust vectoring system. Fluctuating pressure measurements were made in the circular duct upstream and downstream of the valve. This data report presents the results of these tests. The maximum overall sound pressure level is generated in the duct downstream of the valve and reached a value of 180 dB at a valve pressure ratio of 2.8. At the higher valve pressure ratios the spectra downstream of the valve is broad banded with its maximum at 1000 Hz.

  10. Role of irregular otolith afferents in the steady-state nystagmus during off-vertical axis rotation

    NASA Technical Reports Server (NTRS)

    Angelaki, D. E.; Perachio, A. A.; Mustari, M. J.; Strunk, C. L.

    1992-01-01

    1. During constant velocity off-vertical axis rotations (OVAR) in the dark a compensatory ocular nystagmus is present throughout rotation despite the lack of a maintained signal from the semicircular canals. Lesion experiments and canal plugging have attributed the steady-state ocular nystagmus during OVAR to inputs from the otolith organs and have demonstrated that it depends on an intact velocity storage mechanism. 2. To test whether irregularly discharging otolith afferents play a crucial role in the generation of the steady-state eye nystagmus during OVAR, we have used anodal (inhibitory) currents bilaterally to selectively and reversibly block irregular vestibular afferent discharge. During delivery of DC anodal currents (100 microA) bilaterally to both ears, the slow phase eye velocity of the steady-state nystagmus during OVAR was reduced or completely abolished. The disruption of the steady-state nystagmus was transient and lasted only during the period of galvanic stimulation. 3. To distinguish a possible effect of ablation of the background discharge rates of irregular vestibular afferents on the velocity storage mechanism from specific contributions of the dynamic responses from irregular otolith afferents to the circuit responsible for the generation of the steady-state nystagmus, bilateral DC anodal galvanic stimulation was applied during optokinetic nystagmus (OKN) and optokinetic afternystagmus (OKAN). No change in OKN and OKAN was observed.(ABSTRACT TRUNCATED AT 250 WORDS).

  11. Estimating Transient Water Storage from Hurricane Harvey Using GPS Observations of Vertical Land Motion

    NASA Astrophysics Data System (ADS)

    Milliner, C. W. D.; Materna, K.; Burgmann, R.; Fu, Y.; Bekaert, D. P.; Moore, A. W.; Adhikari, S.

    2017-12-01

    The Global Positioning System (GPS) measures elastic ground motions due to variations in terrestrial water mass. Such measurements have been used to successfully study variations of hydrological loading over monthly-to-yearly timescales; e.g., seasonal changes in water storage in California (Argus et al., 2014), 3-year drought of Western US (Borsa et al., 2014) and monthly water storage change in the Pacific Northwest (Fu et al., 2015). However, inferring water storage variations from single loading events over daily-to-weekly timescales presents a major challenge, due to the relatively higher level of noise and systematic errors, such as common mode errors (CME). This makes geodetic investigations of transient hydrologic events, such as major hurricanes, particularly difficult. By using daily vertical GPS timeseries we resolve the spatial and temporal evolution of water loading from Hurricane Harvey across the Gulf coast by applying multiple network correction methods, which helps to isolate the hydrological loading signal. Using 340 GPS stations distributed across the southern US, we mitigate for the effects of spatially correlated CME by firstly removing vertical contributions from atmospheric and non-ocean tidal loading, and secondly correcting the residual positions for changes in translation, rotation and scaling using a Helmert transformation. Our results show a maximum subsidence of 1.8 cm occurring around Houston, and a clear migration of land subsidence from Corpus Christi to western Louisiana over a 7-day period, consistent with the movement of Harvey itself. We also present preliminary results using the Network Inversion Filter (Bekaert et al., 2016), in which we use a Kalman filter approach to describe the time-varying water mass in a stochastic sense. Although our results are preliminary, we find removal of systematic sources of noise can help reveal hydrological loading signals due to extreme, transient events, that would typically go missed by other

  12. Small-Scale Vertical Distribution of Bacterial Biomass and Diversity in Biological Soil Crusts from Arid Lands in the Colorado Plateau

    USGS Publications Warehouse

    Garcia-Pichel, F.; Johnson, S.L.; Youngkin, D.; Belnap, J.

    2003-01-01

    We characterized, at millimeter resolution, bacterial biomass, diversity, and vertical stratification of biological soil crusts in arid lands from the Colorado Plateau. Microscopic counts, extractable DNA, and plate counts of viable aerobic copiotrophs (VAC) revealed that the top centimeter of crusted soils contained atypically large bacterial populations, tenfold larger than those in uncrusted, deeper soils. The plate counts were not always consistent with more direct estimates of microbial biomass. Bacterial populations peaked at the immediate subsurface (1-2 mm) in light-appearing, young crusts, and at the surface (0-1 mm) in well-developed, dark crusts, which corresponds to the location of cyanobacterial populations. Bacterial abundance decreased with depth below these horizons. Spatially resolved DGGE fingerprints of Bacterial 16S rRNA genes demonstrated the presence of highly diverse natural communities, but we could detect neither trends with depth in bacterial richness or diversity, nor a difference in diversity indices between crust types. Fingerprints, however, revealed the presence of marked stratification in the structure of the microbial communities, probably a result of vertical gradients in physicochemical parameters. Sequencing and phylogenetic analyses indicated that most of the naturally occurring bacteria are novel types, with low sequence similarity (83-93%) to those available in public databases. DGGE analyses of the VAC populations indicated communities of lower diversity, with most types having sequences more than 94% similar to those in public databases. Our study indicates that soil crusts represent small-scale mantles of fertility in arid ecosystems, harboring vertically structured, little-known bacterial populations that are not well represented by standard cultivation methods.

  13. 50 CFR 216.11 - Prohibited taking.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ..., DEPARTMENT OF COMMERCE MARINE MAMMALS REGULATIONS GOVERNING THE TAKING AND IMPORTING OF MARINE MAMMALS... jurisdiction of the United States to take any marine mammal on the high seas, or (b) Any person, vessel, or conveyance to take any marine mammal in waters or on lands under the jurisdiction of the United States, or (c...

  14. The Effect of Spray Strips on the Take-off Performance of a Model of a Flying-Boat Hull

    NASA Technical Reports Server (NTRS)

    Truscott, Starr

    1935-01-01

    The effect on the take-off performance of a model of the hull of a typical flying boat, Navy PH-1, of fitting spray strips of four different widths, each at three different angles, was determined by model tests in the NACA Tank. Spray strips of widths up to 3 percent of the beam improve the general performance at speeds near the hump and reduce the spray thrown. A downward angle of 30 degrees to 45 degrees in the neighborhood of the step seems most favorable for the reduction of the spray. The spray strips have a large effect in reducing the trimming moments at speeds near the hump speed, but have little effect on them at high speeds.

  15. Vertically stacked multi-heterostructures of layered materials for logic transistors and complementary inverters

    PubMed Central

    Yu, Woo Jong; Li, Zheng; Zhou, Hailong; Chen, Yu; Wang, Yang; Huang, Yu; Duan, Xiangfeng

    2014-01-01

    The layered materials such as graphene have attracted considerable interest for future electronics. Here we report the vertical integration of multi-heterostructures of layered materials to enable high current density vertical field-effect transistors (VFETs). An n-channel VFET is created by sandwiching few-layer molybdenum disulfide (MoS2) as the semiconducting channel between a monolayer graphene and a metal thin film. The VFETs exhibit a room temperature on-off ratio >103, while at same time deliver a high current density up to 5,000 A/cm2, sufficient for high performance logic applications. This study offers a general strategy for the vertical integration of various layered materials to obtain both p- and n-channel transistors for complementary logic functions. A complementary inverter with larger than unit voltage gain is demonstrated by vertically stacking the layered materials of graphene, Bi2Sr2Co2O8 (p-channel), graphene, MoS2 (n-channel), and metal thin film in sequence. The ability to simultaneously achieve high on-off ratio, high current density, and logic integration in the vertically stacked multi-heterostructures can open up a new dimension for future electronics to enable three-dimensional integration. PMID:23241535

  16. A Flight Study of the Conversion Maneuver of a Tilt-Duct VTOL Aircraft

    NASA Technical Reports Server (NTRS)

    Tapscott, Robert J.; Kelley, Henry L.

    1960-01-01

    Flight records are presented from an early flight test of a wing-tip mounted tilting-ducted-fan, vertical-take-off and landing (VTOL) aircraft configuration. Time histories of the aircraft motions, control positions, and duct pitching-moment variation are presented to illustrate the characteristics of the aircraft in hovering, in conversion from hovering to forward flight, and in conversion from forward flight to hovering. The results indicate that during essentially continuous slow level- flight conversions, this aircraft experiences excessive longitudinal trim changes. Studies have shown that the large trim changes are caused primarily by the variation of aerodynamic moments acting on the duct units. Action of the duct-induced downwash on the horizontal stabilizer during the conversion also contributes to the longitudinal trim variations. Time histories of hovering and slow vertical descent in the final stages of landing in calm air show angular motions of the aircraft as great as +/- 10 deg. about all axes. Stick and pedal displacements required to control the aircraft during the landing maneuver were on the order of 50 to 60 percent of the total travel available.

  17. Model Predictive Control-based Power take-off Control of an Oscillating Water Column Wave Energy Conversion System

    NASA Astrophysics Data System (ADS)

    Rajapakse, G.; Jayasinghe, S. G.; Fleming, A.; Shahnia, F.

    2017-07-01

    Australia’s extended coastline asserts abundance of wave and tidal power. The predictability of these energy sources and their proximity to cities and towns make them more desirable. Several tidal current turbine and ocean wave energy conversion projects have already been planned in the coastline of southern Australia. Some of these projects use air turbine technology with air driven turbines to harvest the energy from an oscillating water column. This study focuses on the power take-off control of a single stage unidirectional oscillating water column air turbine generator system, and proposes a model predictive control-based speed controller for the generator-turbine assembly. The proposed method is verified with simulation results that show the efficacy of the controller in extracting power from the turbine while maintaining the speed at the desired level.

  18. Uncertainty of the 20th century sea-level rise due to vertical land motion errors

    NASA Astrophysics Data System (ADS)

    Santamaría-Gómez, Alvaro; Gravelle, Médéric; Dangendorf, Sönke; Marcos, Marta; Spada, Giorgio; Wöppelmann, Guy

    2017-09-01

    Assessing the vertical land motion (VLM) at tide gauges (TG) is crucial to understanding global and regional mean sea-level changes (SLC) over the last century. However, estimating VLM with accuracy better than a few tenths of a millimeter per year is not a trivial undertaking and many factors, including the reference frame uncertainty, must be considered. Using a novel reconstruction approach and updated geodetic VLM corrections, we found the terrestrial reference frame and the estimated VLM uncertainty may contribute to the global SLC rate error by ± 0.2 mmyr-1. In addition, a spurious global SLC acceleration may be introduced up to ± 4.8 ×10-3 mmyr-2. Regional SLC rate and acceleration errors may be inflated by a factor 3 compared to the global. The difference of VLM from two independent Glacio-Isostatic Adjustment models introduces global SLC rate and acceleration biases at the level of ± 0.1 mmyr-1 and 2.8 ×10-3 mmyr-2, increasing up to 0.5 mm yr-1 and 9 ×10-3 mmyr-2 for the regional SLC. Errors in VLM corrections need to be budgeted when considering past and future SLC scenarios.

  19. Investigation for connecting waveguide in off-planar integrated circuits.

    PubMed

    Lin, Jie; Feng, Zhifang

    2017-09-01

    The transmission properties of a vertical waveguide connected by different devices in off-planar integrated circuits are designed, investigated, and analyzed in detail by the finite-difference time-domain method. The results show that both guide bandwidth and transmission efficiency can be adjusted effectively by shifting the vertical waveguide continuously. Surprisingly, the wide guide band (0.385[c/a]∼0.407[c/a]) and well transmission (-6  dB) are observed simultaneously in several directions when the vertical waveguide is located at a specific location. The results are very important for all-optical integrated circuits, especially in compact integration.

  20. Solving vertical and horizontal well hydraulics problems analytically in Cartesian coordinates with vertical and horizontal anisotropies

    NASA Astrophysics Data System (ADS)

    Batu, Vedat

    2012-01-01

    SummaryA new generalized three-dimensional analytical solution is developed for a partially-penetrating vertical rectangular parallelepiped well screen in a confined aquifer by solving the three-dimensional transient ground water flow differential equation in x- y- z Cartesian coordinates system for drawdown by taking into account the three principal hydraulic conductivities ( Kx, Ky, and Kz) along the x- y- z coordinate directions. The fully penetrating screen case becomes equivalent to the single vertical fracture case of Gringarten and Ramey (1973). It is shown that the new solution and Gringarten and Ramey solution (1973) match very well. Similarly, it is shown that this new solution for a horizontally tiny fully penetrating parallelepiped rectangular parallelepiped screen case match very well with Theis (1935) solution. Moreover, it is also shown that the horizontally tiny partially-penetrating parallelepiped rectangular well screen case of this new solution match very well with Hantush (1964) solution. This new analytical solution can also cover a partially-penetrating horizontal well by representing its screen interval with vertically tiny rectangular parallelepiped. Also the solution takes into account both the vertical anisotropy ( azx = Kz/ Kx) as well as the horizontal anisotropy ( ayx = Ky/ Kx) and has potential application areas to analyze pumping test drawdown data from partially-penetrating vertical and horizontal wells by representing them as tiny rectangular parallelepiped as well as line sources. The solution has also potential application areas for a partially-penetrating parallelepiped rectangular vertical fracture. With this new solution, the horizontal anisotropy ( ayx = Ky/ Kx) in addition to the vertical anisotropy ( azx = Kz/ Kx) can also be determined using observed drawdown data. Most importantly, with this solution, to the knowledge of the author, it has been shown the first time in the literature that some well-known well hydraulics

  1. Species composition and distribution of the Antarctic plunderfishes (Pisces, Artedidraconidae) from the Ross Sea off Victoria Land

    NASA Astrophysics Data System (ADS)

    La Mesa, Mario; Cattaneo-Vietti, Riccardo; Vacchi, Marino

    2006-04-01

    Among the notothenioid fish, the Antarctic plunderfishes (family Artedidraconidae) are a poorly known component of the bottom fauna of the continental shelf despite their relative importance. The family is composed of 25 small- to medium-sized endemic species and four genera, Artedidraco, Dolloidraco, Histiodraco and Pogonophryne, which are the most benthic and sedentary of the notothenioid fish. In the framework of "Victoria Land Transect Project", several samples of plunderfishes were collected by means of an Agassiz trawl. Sampling activities were carried out between 100 and 500 m depth in five sites over nearly 4° latitude off Victoria Land. Overall, trawling yielded 80 specimens of plunderfish, including all species of Artedidraco reported from the Ross Sea, i.e. Artedidraco glareobarbatus, A. loennbergi, A. orianae, A. shackletoni and A. skottsbergi, and the monotypic genus Histiodraco. The use of multivariate statistical analyses on catch data indicated sampling site as the main factor affecting species composition. Histiodraco velifer and A. skottsbergi were caught almost exclusively in the southernmost sites, characterizing the artedidraconid fauna of Cape Russell. A. orianae was sampled only in the northernmost sites, such as Cape Adare and Hallett Peninsula. A. loennbergi appeared to be a ubiquitous species, whereas A. glareobarbatus was caught only at the Hallett Peninsula. Plunderfishes showed a particular distribution pattern in relation to depth as well. A. glareobarbatus was the shallowest species, being sampled within 100 m. A. orianae and A. shackletoni showed a similar distribution, being caught mostly at 100-200 m, whereas A. skottsbergi was mainly sampled at 200-300 m. H. velifer was caught in a wide depth range, but mostly in deeper waters (400 m). A. loennbergi was eurybathic, showing a wider depth distribution than other species. Univariate measures of diversity indicated Cape Adare as the poorer site in terms of species richness and

  2. A variable-collimation display system

    NASA Astrophysics Data System (ADS)

    Batchko, Robert; Robinson, Sam; Schmidt, Jack; Graniela, Benito

    2014-03-01

    Two important human depth cues are accommodation and vergence. Normally, the eyes accommodate and converge or diverge in tandem; changes in viewing distance cause the eyes to simultaneously adjust both focus and orientation. However, ambiguity between accommodation and vergence cues is a well-known limitation in many stereoscopic display technologies. This limitation also arises in state-of-the-art full-flight simulator displays. In current full-flight simulators, the out-the-window (OTW) display (i.e., the front cockpit window display) employs a fixed collimated display technology which allows the pilot and copilot to perceive the OTW training scene without angular errors or distortions; however, accommodation and vergence cues are limited to fixed ranges (e.g., ~ 20 m). While this approach works well for long-range, the ambiguity of depth cues at shorter range hinders the pilot's ability to gauge distances in critical maneuvers such as vertical take-off and landing (VTOL). This is the first in a series of papers on a novel, variable-collimation display (VCD) technology that is being developed under NAVY SBIR Topic N121-041 funding. The proposed VCD will integrate with rotary-wing and vertical take-off and landing simulators and provide accurate accommodation and vergence cues for distances ranging from approximately 3 m outside the chin window to ~ 20 m. A display that offers dynamic accommodation and vergence could improve pilot safety and training, and impact other applications presently limited by lack of these depth cues.

  3. LSD (Landing System Development) Impact Simulation

    NASA Astrophysics Data System (ADS)

    Ullio, R.; Riva, N.; Pellegrino, P.; Deloo, P.

    2012-07-01

    In the frame of the Exploration Programs, a soft landing on the planet surface is foreseen. To ensure a successful final landing phase, a landing system by using leg tripod design landing legs with adequate crushable damping system was selected, capable of absorbing the residual velocities (vertical, horizontal and angular) at touch- down, insuring stability. TAS-I developed a numerical non linear dynamic methodology for the landing impact simulation of the Lander system by using a commercial explicit finite element analysis code (i.e. Altair RADIOSS). In this paper the most significant FE modeling approaches and results of the analytical simulation of landing impact are reported, especially with respect to the definition of leg dimensioning loads and the design update of selected parts (if necessary).

  4. NASA's DC-8 flying laboratory takes off from Juan Santamaria International Airport in San Jose, Costa Rica, on NASA's AirSAR 2004 campaign

    NASA Image and Video Library

    2004-03-03

    NASA's DC-8 flying laboratory takes off from Juan Santamaria International Airport in San Jose, Costa Rica, on NASA's AirSAR 2004 campaign. AirSAR 2004 is a three-week expedition by an international team of scientists that will use an all-weather imaging tool, called the Airborne Synthetic Aperture Radar (AirSAR), in a mission ranging from the tropical rain forests of Central America to frigid Antarctica.

  5. An investigation of errors and data processing techniques for an RF multilateration system. [position and velocity measurements of vertical takeoff aircraft during landing

    NASA Technical Reports Server (NTRS)

    Britt, C. L., Jr.

    1975-01-01

    The development of an RF Multilateration system to provide accurate position and velocity measurements during the approach and landing phase of Vertical Takeoff Aircraft operation is discussed. The system uses an angle-modulated ranging signal to provide both range and range rate measurements between an aircraft transponder and multiple ground stations. Range and range rate measurements are converted to coordinate measurements and the coordinate and coordinate rate information is transmitted by an integral data link to the aircraft. Data processing techniques are analyzed to show advantages and disadvantages. Error analyses are provided to permit a comparison of the various techniques.

  6. Consequences of land use and land cover change

    USGS Publications Warehouse

    Slonecker, E. Terrence; Barnes, Christopher; Karstensen, Krista; Milheim, Lesley E.; Roig-Silva, Coral M.

    2013-01-01

    The U.S. Geological Survey (USGS) Climate and Land Use Change Mission Area is one of seven USGS mission areas that focuses on making substantial scientific "...contributions to understanding how Earth systems interact, respond to, and cause global change". Using satellite and other remotely sensed data, USGS scientists monitor patterns of land cover change over space and time at regional, national, and global scales. These data are analyzed to understand the causes and consequences of changing land cover, such as economic impacts, effects on water quality and availability, the spread of invasive species, habitats and biodiversity, carbon fluctuations, and climate variability. USGS scientists are among the leaders in the study of land cover, which is a term that generally refers to the vegetation and artificial structures that cover the land surface. Examples of land cover include forests, grasslands, wetlands, water, crops, and buildings. Land use involves human activities that take place on the land. For example, "grass" is a land cover, whereas pasture and recreational parks are land uses that produce a cover of grass.

  7. Effect of Footwear on Dynamic Stability during Single-leg Jump Landings.

    PubMed

    Bowser, Bradley J; Rose, William C; McGrath, Robert; Salerno, Jilian; Wallace, Joshua; Davis, Irene S

    2017-06-01

    Barefoot and minimal footwear running has led to greater interest in the biomechanical effects of different types of footwear. The effect of running footwear on dynamic stability is not well understood. The purpose of this study was to compare dynamic stability and impact loading across 3 footwear conditions; barefoot, minimal footwear and standard running shoes. 25 injury free runners (21 male, 4 female) completed 5 single-leg jump landings in each footwear condition. Dynamic stability was assessed using the dynamic postural stability index and its directional components (mediolateral, anteroposterior, vertical). Peak vertical ground reaction force and vertical loadrates were also compared across footwear conditions. Dynamic stability was dependent on footwear type for all stability indices (ANOVA, p<0.05). Post-hoc tests showed dynamic stability was greater when barefoot than in running shoes for each stability index (p<0.02) and greater than minimal footwear for the anteroposterior stability index (p<0.01). Peak vertical force and average loadrates were both dependent on footwear (p≤0.05). Dynamic stability, peak vertical force, and average loadrates during single-leg jump landings appear to be affected by footwear type. The results suggest greater dynamic stability and lower impact loading when landing barefoot or in minimal footwear. © Georg Thieme Verlag KG Stuttgart · New York.

  8. An oscillating wave energy converter with nonlinear snap-through Power-Take-Off systems in regular waves

    NASA Astrophysics Data System (ADS)

    Zhang, Xian-tao; Yang, Jian-min; Xiao, Long-fei

    2016-07-01

    Floating oscillating bodies constitute a large class of wave energy converters, especially for offshore deployment. Usually the Power-Take-Off (PTO) system is a directly linear electric generator or a hydraulic motor that drives an electric generator. The PTO system is simplified as a linear spring and a linear damper. However the conversion is less powerful with wave periods off resonance. Thus, a nonlinear snap-through mechanism with two symmetrically oblique springs and a linear damper is applied in the PTO system. The nonlinear snap-through mechanism is characteristics of negative stiffness and double-well potential. An important nonlinear parameter γ is defined as the ratio of half of the horizontal distance between the two springs to the original length of both springs. Time domain method is applied to the dynamics of wave energy converter in regular waves. And the state space model is used to replace the convolution terms in the time domain equation. The results show that the energy harvested by the nonlinear PTO system is larger than that by linear system for low frequency input. While the power captured by nonlinear converters is slightly smaller than that by linear converters for high frequency input. The wave amplitude, damping coefficient of PTO systems and the nonlinear parameter γ affect power capture performance of nonlinear converters. The oscillation of nonlinear wave energy converters may be local or periodically inter well for certain values of the incident wave frequency and the nonlinear parameter γ, which is different from linear converters characteristics of sinusoidal response in regular waves.

  9. What Is the Contribution of City-Scale Actions to the Overall Food System's Environmental Impacts?: Assessing Water, Greenhouse Gas, and Land Impacts of Future Urban Food Scenarios.

    PubMed

    Boyer, Dana; Ramaswami, Anu

    2017-10-17

    This paper develops a methodology for individual cities to use to analyze the in- and trans-boundary water, greenhouse gas (GHG), and land impacts of city-scale food system actions. Applied to Delhi, India, the analysis demonstrates that city-scale action can rival typical food policy interventions that occur at larger scales, although no single city-scale action can rival in all three environmental impacts. In particular, improved food-waste management within the city (7% system-wide GHG reduction) matches the GHG impact of preconsumer trans-boundary food waste reduction. The systems approach is particularly useful in illustrating key trade-offs and co-benefits. For instance, multiple diet shifts that can reduce GHG emissions have trade-offs that increase water and land impacts. Vertical farming technology (VFT) with current applications for fruits and vegetables can provide modest system-wide water (4%) and land reductions (3%), although implementation within the city itself may raise questions of constraints in water-stressed cities, with such a shift in Delhi increasing community-wide direct water use by 16%. Improving the nutrition status for the bottom 50% of the population to the median diet is accompanied by proportionally smaller increases of water, GHG, and land impacts (4%, 9%, and 8%, systemwide): increases that can be offset through simultaneous city-scale actions, e.g., improved food-waste management and VFT.

  10. Vertical distributions of (99)Tc and the (99)Tc/(137)Cs activity ratio in the coastal water off Aomori, Japan.

    PubMed

    Nakanishi, Takahiro; Zheng, Jian; Aono, Tatsuo; Yamada, Masatoshi; Kusakabe, Masashi

    2011-08-01

    Using a sector-field ICP-MS the vertical distributions of the (99)Tc concentration and (99)Tc/(137)Cs activity ratio were measured in the coastal waters off Aomori Prefecture, Japan, where a spent-nuclear-fuel reprocessing plant has begun test operation. The (99)Tc concentrations in surface water ranged from 1.8 to 2.4 mBq/m(3), no greater than the estimated background level. Relatively high (99)Tc/(137)Cs activity ratios (10-12 × 10(-4)) would be caused by the inflow of the high-(99)Tc/(137)Cs water mass from the Japan Sea. There is no observable contamination from the reprocessing plant in the investigated area. The (99)Tc concentration and the (99)Tc/(137)Cs activity ratio in water column showed gradual decreases with depth. Our results implied that (99)Tc behaves in a more conservative manner than (137)Cs in marine environments. Copyright © 2011 Elsevier Ltd. All rights reserved.

  11. X-33

    NASA Image and Video Library

    2004-04-15

    This is an artist's concept of the completely operational International Space Station being approached by an X-33 Reusable Launch Vehicle (RLV). The X-33 program was designed to pave the way to a full-scale, commercially developed RLV as the flagship technology demonstrator for technologies that would lower the cost of access to space. It is unpiloted, taking off vertically like a rocket, reaching an altitude of up to 60 miles and speeds between Mach 13 and 15, and landing horizontally like an airplane. The X-33 program was cancelled in 2001.

  12. It's not what you put on, but what you take off: techniques for debriding and off-loading the diabetic foot wound.

    PubMed

    Armstrong, David G; Lavery, Lawrence A; Nixon, Brent P; Boulton, Andrew J M

    2004-08-01

    The basic etiology of neuropathic diabetic foot wounds involves pressure in conjunction with cycles of repetitive stress, leading to failure of skin and soft tissue. The central tenet of any treatment plan addressing neuropathic diabetic foot wounds is the appropriate debridement of nonviable tissue coupled with adequate pressure relief (off-loading). Although numerous advances have been made in the treatment of diabetic foot wounds, including bioengineered tissues, autologous and exogenous cytokine delivery systems, and potentially effective topical antimicrobial modalities, none will succeed without addressing effective debridement and off-loading. Specific debridement and off-loading techniques are discussed, along with available supporting evidence. This includes the use of the "instant" total contact cast, among other modalities.

  13. Songbird - AN Innovative Uas Combining the Advantages of Fixed Wing and Multi Rotor Uas

    NASA Astrophysics Data System (ADS)

    Thamm, F.-P.; Brieger, N.; Neitzke, K.-P.; Meyer, M.; Jansen, R.; Mönninghof, M.

    2015-08-01

    This paper describes a family of innovative fixed wing UAS with can vertical take off and land - the SONGBIRD family. With nominal payloads starting from 0.5 kg they can take off and land safely like a multi-rotor UAV, removing the need for an airstrip for the critical phases of operation. A specially designed flight controller allows stable flight at every point of the transition phase between VTOL and fixed wing mode. Because of this smooth process with a all time stable flight, very expensive payload like hyperspectral sensors or advanced optical cameras can be used. Due to their design all airplanes of the SONGBIRD family have excellent horizontal flight properties, a maximum speed of over 110 km/h, good gliding properties and long flight times of up to 1 h. Missions were flown in wind speeds up to 18 m/s. At every time of the flight it is possible to interrupt the mission and hover over a point of interest for detail investigations. The complete flight, including take-off and landing can be performed by autopilot. Designed for daily use in professional environments, SONGBIRDs are built out of glass-fibre and carbon composites for a long service life. For safe operations comprehensive security features are implemented, for example redundant flight controllers and sensors, advanced power management system and mature fail safe procedures. The aircraft can be dismantled into small parts for transportation. SONGBIRDS are available for different pay loads, from 500 g to 2 kg. The SONGBIRD family are interesting tools combining the advantages of multi-copter and fixed wing UAS.

  14. Phoenix Lander on Mars with Surrounding Terrain, Vertical Projection

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This view is a vertical projection that combines more than 500 exposures taken by the Surface Stereo Imager camera on NASA's Mars Phoenix Lander and projects them as if looking down from above.

    The black circle on the spacecraft is where the camera itself is mounted on the lander, out of view in images taken by the camera. North is toward the top of the image. The height of the lander's meteorology mast, extending toward the southwest, appears exaggerated because that mast is taller than the camera mast.

    This view in approximately true color covers an area about 30 meters by 30 meters (about 100 feet by 100 feet). The landing site is at 68.22 degrees north latitude, 234.25 degrees east longitude on Mars.

    The ground surface around the lander has polygonal patterning similar to patterns in permafrost areas on Earth.

    This view comprises more than 100 different Stereo Surface Imager pointings, with images taken through three different filters at each pointing. The images were taken throughout the period from the 13th Martian day, or sol, after landing to the 47th sol (June 5 through July 12, 2008). The lander's Robotic Arm is cut off in this mosaic view because component images were taken when the arm was out of the frame.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  15. A Comparison of the Habitual Landing Strategies from Differing Drop Heights of Parkour Practitioners (Traceurs) and Recreationally Trained Individuals.

    PubMed

    Standing, Regan J; Maulder, Peter S

    2015-12-01

    Parkour is an activity that encompasses methods of jumping, climbing and vaulting. With landing being a pertinent part of this practise, Parkour participants (traceurs) have devised their own habitual landing strategies, which are suggested to be a safer and more effective style of landing. The purpose of this study was to compare the habitual landing strategies of traceurs and recreationally trained individuals from differing drop heights. Comparisons between landing sound and mechanical parameters were also assessed to gauge the level of landing safety. Ten recreationally trained participants and ten traceurs performed three landings from 25% and 50% body height using their own habitual landing strategies. Results at 25% showed significantly lower maximal vertical force (39.9%, p < 0.0013, ES = -1.88), longer times to maximal vertical force (68.6%, p < 0.0015, ES = 1.72) and lower loading rates (65.1%, p < 0.0002, ES = -2.22) in the traceur group. Maximal sound was also shown to be lower (3.6%), with an effect size of -0.63, however this was not statistically significant (p < 0.1612). At 50%, traceurs exhibited significantly different values within all variables including maximal sound (8.6%, p < 0.03, ES = -1.04), maximal vertical force (49.0%, p < 0.0002, ES = -2.38), time to maximal vertical force (65.9%, p < 0.0067, ES = 1.32) and loading rates (66.3%, p < 0.0002, ES = -2.00). Foot strike analysis revealed traceurs landed using forefoot or forefoot-midfoot strategies in 93.2% of trials; whereas recreationally trained participants used these styles in only 8.3% of these landings. To conclude, the habitual landings of traceurs are more effective at lowering the kinetic landing variables associated with a higher injury risk in comparison to recreationally trained individuals. Sound as a measure of landing effectiveness and safety holds potential significance; however requires further research to confirm. Key pointsHabitual traceur landings were observed to be

  16. Global land use change, economic globalization, and the looming land scarcity.

    PubMed

    Lambin, Eric F; Meyfroidt, Patrick

    2011-03-01

    A central challenge for sustainability is how to preserve forest ecosystems and the services that they provide us while enhancing food production. This challenge for developing countries confronts the force of economic globalization, which seeks cropland that is shrinking in availability and triggers deforestation. Four mechanisms-the displacement, rebound, cascade, and remittance effects-that are amplified by economic globalization accelerate land conversion. A few developing countries have managed a land use transition over the recent decades that simultaneously increased their forest cover and agricultural production. These countries have relied on various mixes of agricultural intensification, land use zoning, forest protection, increased reliance on imported food and wood products, the creation of off-farm jobs, foreign capital investments, and remittances. Sound policies and innovations can therefore reconcile forest preservation with food production. Globalization can be harnessed to increase land use efficiency rather than leading to uncontrolled land use expansion. To do so, land systems should be understood and modeled as open systems with large flows of goods, people, and capital that connect local land use with global-scale factors.

  17. Global land use change, economic globalization, and the looming land scarcity

    PubMed Central

    Lambin, Eric F.; Meyfroidt, Patrick

    2011-01-01

    A central challenge for sustainability is how to preserve forest ecosystems and the services that they provide us while enhancing food production. This challenge for developing countries confronts the force of economic globalization, which seeks cropland that is shrinking in availability and triggers deforestation. Four mechanisms—the displacement, rebound, cascade, and remittance effects—that are amplified by economic globalization accelerate land conversion. A few developing countries have managed a land use transition over the recent decades that simultaneously increased their forest cover and agricultural production. These countries have relied on various mixes of agricultural intensification, land use zoning, forest protection, increased reliance on imported food and wood products, the creation of off-farm jobs, foreign capital investments, and remittances. Sound policies and innovations can therefore reconcile forest preservation with food production. Globalization can be harnessed to increase land use efficiency rather than leading to uncontrolled land use expansion. To do so, land systems should be understood and modeled as open systems with large flows of goods, people, and capital that connect local land use with global-scale factors. PMID:21321211

  18. Trajectory optimization for lunar soft landing with complex constraints

    NASA Astrophysics Data System (ADS)

    Chu, Huiping; Ma, Lin; Wang, Kexin; Shao, Zhijiang; Song, Zhengyu

    2017-11-01

    A unified trajectory optimization framework with initialization strategies is proposed in this paper for lunar soft landing for various missions with specific requirements. Two main missions of interest are Apollo-like Landing from low lunar orbit and Vertical Takeoff Vertical Landing (a promising mobility method) on the lunar surface. The trajectory optimization is characterized by difficulties arising from discontinuous thrust, multi-phase connections, jump of attitude angle, and obstacles avoidance. Here R-function is applied to deal with the discontinuities of thrust, checkpoint constraints are introduced to connect multiple landing phases, attitude angular rate is designed to get rid of radical changes, and safeguards are imposed to avoid collision with obstacles. The resulting dynamic problems are generally with complex constraints. The unified framework based on Gauss Pseudospectral Method (GPM) and Nonlinear Programming (NLP) solver are designed to solve the problems efficiently. Advanced initialization strategies are developed to enhance both the convergence and computation efficiency. Numerical results demonstrate the adaptability of the framework for various landing missions, and the performance of successful solution of difficult dynamic problems.

  19. Airplane takeoff and landing performance monitoring system

    NASA Technical Reports Server (NTRS)

    Middleton, David B. (Inventor); Srivatsan, Raghavachari (Inventor); Person, Lee H. (Inventor)

    1989-01-01

    The invention is a real-time takeoff and landing performance monitoring system which provides the pilot with graphic and metric information to assist in decisions related to achieving rotation speed (V sub R) within the safe zone of the runway or stopping the aircraft on the runway after landing or take off abort. The system processes information in two segments: a pretakeoff segment and a real-time segment. One-time inputs of ambient conditions and airplane configuration information are used in the pretakeoff segment to generate scheduled performance data. The real-time segment uses the scheduled performance data, runway length data and transducer measured parameters to monitor the performance of the airplane throughout the takeoff roll. An important feature of this segment is that it updates the estimated runway rolling friction coefficient. Airplane performance predictions also reflect changes in headwind occurring as the takeoff roll progresses. The system displays the position of the airplane on the runway, indicating runway used and runway available, summarizes the critical information into a situation advisory flag, flags engine failures and off-nominal acceleration performance, and indicates where on the runway particular events such as decision speed (V sub 1), rotation speed (V sub R) and expected stop points will occur based on actual or predicted performance. The display also indicates airspeed, wind vector, engine pressure ratios, second segment climb speed, and balanced field length (BFL). The system detects performance deficiencies by comparing the airplane's present performance with a predicted nominal performance based upon the given conditions.

  20. Preliminary Sizing of Vertical Take-off Rocket-based Combined-cycle Powered Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Roche, Joseph M.; McCurdy, David R.

    2001-01-01

    The task of single-stage-to-orbit has been an elusive goal due to propulsion performance, materials limitations, and complex system integration. Glenn Research Center has begun to assemble a suite of relationships that tie Rocket-Based Combined-Cycle (RBCC) performance and advanced material data into a database for the purpose of preliminary sizing of RBCC-powered launch vehicles. To accomplish this, a near optimum aerodynamic and structural shape was established as a baseline. The program synthesizes a vehicle to meet the mission requirements, tabulates the results, and plots the derived shape. A discussion of the program architecture and an example application is discussed herein.

  1. Air pollution from future giant jetports

    NASA Technical Reports Server (NTRS)

    Fay, J. A.

    1970-01-01

    Because aircraft arrive and depart in a generally upwind direction, the pollutants are deposited in a narrow corridor extending downwind of the airport. Vertical mixing in the turbulent atmosphere will not dilute such a trail, since the pollutants are distributed vertically during the landing and take-off operations. As a consequence, airport pollution may persist twenty to forty miles downwind without much attenuation. Based on this simple meteorological model, calculations of the ambient levels of nitric oxide and particulates to be expected downwind of a giant jetport show them to be about equal to those in present urban environments. These calculations are based on measured emission rates from jet engines and estimates of aircraft performance and traffic for future jetports.

  2. Handling Qualities of Large Rotorcraft in Hover and Low Speed

    NASA Technical Reports Server (NTRS)

    Malpica, Carlos; Theodore, Colin R.; Lawrence , Ben; Blanken, Chris L.

    2015-01-01

    According to a number of system studies, large capacity advanced rotorcraft with a capability of high cruise speeds (approx.350 mph) as well as vertical and/or short take-off and landing (V/STOL) flight could alleviate anticipated air transportation capacity issues by making use of non-primary runways, taxiways, and aprons. These advanced aircraft pose a number of design challenges, as well as unknown issues in the flight control and handling qualities domains. A series of piloted simulation experiments have been conducted on the NASA Ames Research Center Vertical Motion Simulator (VMS) in recent years to systematically investigate the fundamental flight control and handling qualities issues associated with the characteristics of large rotorcraft, including tiltrotors, in hover and low-speed maneuvering.

  3. 20. DETAIL OF VERTICAL POWER HACKSAW, POWER HACKSAW (NOT ORIGINAL), ...

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

    20. DETAIL OF VERTICAL POWER HACKSAW, POWER HACKSAW (NOT ORIGINAL), AND TWIST-DRILL GRINDER (L TO R) LOOKING SOUTHWEST. - W. A. Young & Sons Foundry & Machine Shop, On Water Street along Monongahela River, Rices Landing, Greene County, PA

  4. ULR Re-analysed Global GPS Solution for Vertical Land Motion Correction at Tide Gauges

    NASA Astrophysics Data System (ADS)

    Letetrel, C.; Wöppelmann, G.; Bouin, M.; Altamimi, Z.; Martine, F.; Santamaria, A.

    2007-12-01

    The presentation will review the recent results published by Wöppelmann et al. (2007) in Global and Planetary Change. Geocentric sea-level trend estimates were derived from the global GPS analyses conducted at ULR consortium to correct a set of relevant tide gauges from the vertical motion of the land upon which they are settled. The exercise proved worthwhile. The results showed a reduced dispersion of the estimated sea level trends, either regionally or globally, after application of the GPS corrections compared to the corrections derived from the glacio-isostatic adjustment models of Peltier (2004). Here we will focus on two important issues that were not addressed in Wöppelmann et al. (2007). The first issue concerns the noise content of our GPS solutions. Previous works have shown that GPS coordinate time series are subject to significant time-correlated (coloured) noise, with a large predominance of flicker noise (Zhang et al. 1997, Mao et al. 1999, Williams et al. 2004). The presence of coloured noise in a time series has a significant effect on the rate uncertainty, which may otherwise be underestimated by as much as an order of magnitude. We therefore carefully investigate the now 10-year long data set of reanalysed GPS solutions for noise content using the Allan variance technique (Feissel et al. 2007). Preliminary results show that the reanalysed solutions at ULR exhibit far less flicker noise than any other solution published so far in the literature available to us. The percentage of stations with flicker noise drops to only about 20%. These encouraging results advocate for a comprehensive reanalysis strategy with full coherent models over the entire observation data span. Moreover, the noise level reaches the best levels of other geodetic results recently published, namely the VLBI level in the horizontal component and the SLR level in the vertical component (Feissel et al. 2007). The second issue that we would like to address in the presentation

  5. A Unified Global Reference Frame of Vertical Crustal Movements by Satellite Laser Ranging.

    PubMed

    Zhu, Xinhui; Wang, Ren; Sun, Fuping; Wang, Jinling

    2016-02-08

    Crustal movement is one of the main factors influencing the change of the Earth system, especially in its vertical direction, which affects people's daily life through the frequent occurrence of earthquakes, geological disasters, and so on. In order to get a better study and application of the vertical crustal movement,as well as its changes, the foundation and prerequisite areto devise and establish its reference frame; especially, a unified global reference frame is required. Since SLR (satellite laser ranging) is one of the most accurate space techniques for monitoring geocentric motion and can directly measure the ground station's geocentric coordinates and velocities relative to the centre of the Earth's mass, we proposed to take the vertical velocity of the SLR technique in the ITRF2008 framework as the reference frame of vertical crustal motion, which we defined as the SLR vertical reference frame (SVRF). The systematic bias between other velocity fields and the SVRF was resolved by using the GPS (Global Positioning System) and VLBI (very long baseline interferometry) velocity observations, and the unity of other velocity fields and SVRF was realized,as well. The results show that it is feasible and suitable to take the SVRF as a reference frame, which has both geophysical meanings and geodetic observations, so we recommend taking the SLR vertical velocity under ITRF2008 as the global reference frame of vertical crustal movement.

  6. Landing Energy Dissipation for Manned Reentry Vehicles

    NASA Technical Reports Server (NTRS)

    Fisher, Loyd. L.

    1960-01-01

    The film shows experimental investigations to determine the landing-energy-dissipation characteristics for several types of landing gear for manned reentry vehicles. The landing vehicles are considered in two categories: those having essentially vertical-descent paths, the parachute-supported vehicles, and those having essentially horizontal paths, the lifting vehicles. The energy-dissipation devices include crushable materials such as foamed plastics and honeycomb for internal application in couch-support systems, yielding metal elements as part of the structure of capsules or as alternates for oleos in landing-gear struts, inflatable bags, braking rockets, and shaped surfaces for water impact.

  7. A Multi-Modality Mobility Concept for a Small Package Delivery UAV

    NASA Technical Reports Server (NTRS)

    Young, L. A.

    2017-01-01

    This paper will discuss a different approach to the typical notional small package delivery drone concept. Most delivery drone concepts employ a point-to-point aerial delivery CONOPS (Concept of Operations) from a warehouse directly to the front or back yards of a customers residence or a commercial office space. Instead, the proposed approach is somewhat analogous to current postal deliveries: a small aerial vehicle flies from a warehouse to designated neighborhood VTOL (Vertical Take-Off and Landing) landing spots where the aerial vehicle then converts to a "roadable" (ground-mobility) vehicle that then transits on sidewalks and/or bicycle paths till it arrives to the residence/office drop-off points. This concept and associated platform or vehicle will be referred in this paper as MICHAEL (Multimodal Intra-City Hauling and Aerial-Effected Logistics) concept. It is suggested that the MICHAEL concept potentially results in a more community friendly "delivery drone" approach.

  8. Analysis of the Vertical Ground Reaction Forces and Temporal Factors in the Landing Phase of a Countermovement Jump

    PubMed Central

    Ortega, Daniel Rojano; Rodríguez Bíes, Elisabeth C.; Berral de la Rosa, Francisco J.

    2010-01-01

    In most common bilateral landings of vertical jumps, there are two peak forces (F1 and F2) in the force-time curve. The combination of these peak forces and the high frequency of jumps during sports produce a large amount of stress in the joints of the lower limbs which can be determinant of injury. The aim of this study was to find possible relationships between the jump height and F1 and F2, between F1 and F2 themselves, and between F1, F2, the time they appear (T1 and T2, respectively) and the length of the impact absorption phase (T). Thirty semi-professional football players made five countermovement jumps and the highest jump of each player was analyzed. They were instructed to perform the jumps with maximum effort and to land first with the balls of their feet and then with their heels. All the data were collected using a Kistler Quattro Jump force plate with a sample rate of 500 Hz. Quattro Jump Software, v.1.0.9.0., was used. There was neither significant correlation between T1 and F1 nor between T1 and F2. There was a significant positive correlation between flight height (FH) and F1 (r = 0.584, p = 0.01) but no significant correlation between FH and F2. A significant positive correlation between F1 and T2 (r = 0.418, p < 0.05) and a significant negative correlation between F2 and T2 (r = -0.406, p < 0.05) were also found. There is a significant negative correlation between T2 and T (r = -0. 443, p < 0.05). T1 has a little effect in the impact absorption process. F1 increases with increasing T2 but F2 decreases with increasing T2. Besides, increasing T2, with the objective of decreasing F2, makes the whole impact absorption shorter and the jump landing faster. Key points In the landing phase of a jump there are always sev-eral peak forces. The combination of these peaks forces and the high frequency of jumps during sports produces a large amount of stress in the joints of the lower limbs which can be determinant of injury. In the most common two

  9. Central coast designs: The Eightball Express. Taking off with convention, cruising with improvements and landing with absolute success

    NASA Technical Reports Server (NTRS)

    Davis, Ryan Edwin; Dawson, Anne Marie; Fecht, Paul Hans; Fry, Roman Zyabash; Vantriet, Robert; Macabantad, Dominique Dujale; Miller, Robert Glenn; Perez, Gustavo, Jr.; Weise, Timothy Michael

    1994-01-01

    The airline industry is very competitive, resulting in most U.S. and many international airlines being unprofitable. Because of this competition the airlines have been engaging in fare wars (which reduce revenue generated by transporting passengers) while inflation has increased. This situation of course is not developing revenue for the airlines. To revive the airlines to profitability, the difference between revenue received and airline operational cost must be improved. To solve these extreme conditions, the Eightball Express was designed with the main philosophy of developing an aircraft with a low direct operating cost and acquisition cost. Central Coast Designs' (CCD) aircraft utilizes primarily aluminum in the structure to minimize manufacturing cost, supercritical airfoil sections to minimize drag, and fuel efficient engines to minimize fuel burn. Furthermore, the aircraft was designed using Total Quality Management and Integrated Product Development to minimize development and manufacturing costs. Using these primary cost reduction techniques, the Eightball Express was designed to meet the Lockheed/AIAA Request for Proposal (RFP) requirements of a low cost, 153 passenger, 3000 nm. range transport. The Eightball Express is able to takeoff on less than a 7000 ft. runway, cruise at Mach 0.82 at an altitude of 36,000 ft. for a range of 3,000 nm., and lands on a 5,000 ft. runway. lt is able to perform this mission at a direct operating cost of 3.51 cents/available seat mile in 1992 dollars while the acquisition cost is only $28 million in 1992 dollars. By utilizing and improving on proven technologies, CCD has produced an efficient low cost commercial transport for the future.

  10. 25 CFR 226.23 - Easements for wells off leased premises.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... OSAGE RESERVATION LANDS FOR OIL AND GAS MINING Operations § 226.23 Easements for wells off leased premises. The Superintendent, with the consent of the Osage Tribal Council, may grant commercial and noncommercial easements for wells off the leased premises to be used for purposes associated with oil and gas...

  11. Preface: Workshop on Off-Grid Technology Systems

    NASA Astrophysics Data System (ADS)

    Alonso-Marroquin, Fernando

    2017-06-01

    Off-grid houses are dwellings that do not rely on water supply, sewer, or electrical power grid, and are able to operate independently of all public utility services. These houses are ideal for remote communities or population suffering natural or human-made disasters. Our aim is to develop compact and affordable off-grid technologies by integrating high-end nano-engineering with systems that imitates natural biological processes. The key areas of focus in the workshop were: solar energy harvesting using nanotechnology, wind energy harvesting from vertical-axis wind turbines, supercapacitors energy storage systems, treatment of greywater, and green roofs to achieve air comfort.

  12. A rapid method for optimization of the rocket propulsion system for single-stage-to-orbit vehicles

    NASA Technical Reports Server (NTRS)

    Eldred, C. H.; Gordon, S. V.

    1976-01-01

    A rapid analytical method for the optimization of rocket propulsion systems is presented for a vertical take-off, horizontal landing, single-stage-to-orbit launch vehicle. This method utilizes trade-offs between propulsion characteristics affecting flight performance and engine system mass. The performance results from a point-mass trajectory optimization program are combined with a linearized sizing program to establish vehicle sizing trends caused by propulsion system variations. The linearized sizing technique was developed for the class of vehicle systems studied herein. The specific examples treated are the optimization of nozzle expansion ratio and lift-off thrust-to-weight ratio to achieve either minimum gross mass or minimum dry mass. Assumed propulsion system characteristics are high chamber pressure, liquid oxygen and liquid hydrogen propellants, conventional bell nozzles, and the same fixed nozzle expansion ratio for all engines on a vehicle.

  13. Effects of Fragmentation and Sea-Level Changes upon Frog Communities of Land-Bridge Islands off the Southeastern Coast of Brazil

    PubMed Central

    Bittencourt-Silva, Gabriela B.; Silva, Hélio R.

    2014-01-01

    We investigate the composition of anuran communities of land-bridge islands off the southeastern coast of Brazil. These islands provide natural long-term experiments on the effects of fragmentation in the Brazilian Atlantic Forest (BAF). We hypothesize that Pleistocene sea-level changes, in combination with other abiotic variables such as area and habitat diversity, has affected anuran species richness and community composition on these islands. Data from the literature and collections databases were used to produce species lists for eight land-bridge islands and for the mainland adjacent to the islands. We assess the effects of area, number of breeding habitats and distance to the mainland upon anuran species richness on land-bridge islands. Additionally we use nestedness analysis to quantify the extent to which the species on smaller and less habitat-diverse islands correspond to subsets of those on larger and more diverse ones. We found that area has both direct and indirect effects on anuran species richness on land-bridge islands, irrespective of distance to the mainland. However, on islands with comparable sizes, differences in species richness can be attributed to the number and quality of breeding habitats. Anuran communities on these islands display a nested pattern, possibly caused by selective extinction related to habitat loss. Common lowland pond-breeders were conspicuous by their absence. In the BAF, the conservation of fragments with a high diversity of breeding habitats could compensate for the generally negative effect of small area upon species richness. We suggest that sea-level changes have an important role in shaping composition of anuran species on coastal communities. PMID:25068643

  14. Quadriceps force and anterior tibial force occur obviously later than vertical ground reaction force: a simulation study.

    PubMed

    Ueno, Ryo; Ishida, Tomoya; Yamanaka, Masanori; Taniguchi, Shohei; Ikuta, Ryohei; Samukawa, Mina; Saito, Hiroshi; Tohyama, Harukazu

    2017-11-18

    Although it is well known that quadriceps force generates anterior tibial force, it has been unclear whether quadriceps force causes great anterior tibial force during the early phase of a landing task. The purpose of the present study was to examine whether the quadriceps force induced great anterior tibial force during the early phase of a landing task. Fourteen young, healthy, female subjects performed a single-leg landing task. Muscle force and anterior tibial force were estimated from motion capture data and synchronized force data from the force plate. One-way repeated measures analysis of variance and the post hoc Bonferroni test were conducted to compare the peak time of the vertical ground reaction force, quadriceps force and anterior tibial force during the single-leg landing. In addition, we examined the contribution of vertical and posterior ground reaction force, knee flexion angle and moment to peak quadriceps force using multiple linear regression. The peak times of the estimated quadriceps force (96.0 ± 23.0 ms) and anterior tibial force (111.9 ± 18.9 ms) were significantly later than that of the vertical ground reaction force (63.5 ± 6.8 ms) during the single-leg landing. The peak quadriceps force was positively correlated with the peak anterior tibial force (R = 0.953, P < 0.001). Multiple linear regression analysis showed that the peak knee flexion moment contributed significantly to the peak quadriceps force (R 2  = 0.778, P < 0.001). The peak times of the quadriceps force and the anterior tibial force were obviously later than that of the vertical ground reaction force for the female athletes during successful single-leg landings. Studies have reported that the peak time of the vertical ground reaction force was close to the time of anterior cruciate ligament (ACL) disruption in ACL injury cases. It is possible that early contraction of the quadriceps during landing might induce ACL disruption as a result of

  15. An air-breathing ballistic space transporter for Europe

    NASA Technical Reports Server (NTRS)

    Kramer, P. A.; Buehler, R. D.

    1985-01-01

    With increasing transport requirements, reusable space transporters again receive serious consideration in Europe as successors to the Ariane family. The paper deals with a hydrogen-ramjet-propelled, 1-1/2-stage reusable ballistic space transporter with vertical take-off and landing and using liquid hydrogen/oxygen rockets. This novel concept was developed in a theoretical study at the University of Stuttgart. The results are compared with recently published studies of several other European space transporter concepts. The data derived for the Istra - concept are: 15.4 Mg payload into low Earth-orbit, 155 Mg gross lift-off mass, 10% payload ratio, which represents a 57% propellant saving, and 44% reduction in dry mass (structure and engines) compared with comparable two-stage pure rocket concepts.

  16. Seasonal abundance and vertical distribution of capelin (Mallotus villosus) in relation to water temperature at a coastal site off eastern Newfoundland

    USGS Publications Warehouse

    Methven, David A.; Piatt, John F.

    1991-01-01

    The seasonal abundance and vertical distribution of capelin in relation to water temperature have been investigated by conducting repeated hydroacoustic surveys at a coastal site off eastern Newfoundland. Water temperatures were warmer in 1983 than in 1984 as indicated by the earlier appearance and greater depth of the seasonal thermocline. Correspondingly, schools of capelin appeared earlier, were more abundant, and extended deeper in the water column in 1983 than in 1984. Most capelin were found between the surface and the 5°C isotherm. In both years, initial peaks of capelin abundance occurred when nearshore water temperatures increased from about 0-1°C to above 6°C and, at or near, periods of maximum tidal oscillation. Short-term variations in the depth of the 5°C isotherm were related to nearshore wind-induced upwelling events. Annual variations corresponded to the volume of cold (>0°C) water and sea-ice transported south by the Labrador Current.

  17. Fugitive dust emissions from off-road vehicle maneuvers on military training lands

    USDA-ARS?s Scientific Manuscript database

    Off-road vehicle training can contribute to air quality degradation because of increased wind erosion as a result of soil disruption during high wind events. However, limited information exists regarding the impacts of off-road vehicle maneuvering on wind erosion potential of soils. This study was c...

  18. Growth of Planted Yellow-Poplar After Vertical Mulching and Fertilization on Eroded Soils

    Treesearch

    J.B. Baker; B.G. Blackmon

    1976-01-01

    Fertilization and vertical mulching improved height growth of yellow-poplars planted on eroded soils. A growing demand for hardwood timber accompanied by a diminishing land base has prompted land managers to consider planting hardwoods on marginal sites such as the eroded soils in the Silty Uplands of Arkansas, Louisiana, and Mississippi. Many of these areas were well...

  19. Future launcher demonstrator. Challenge and pathfinder

    NASA Astrophysics Data System (ADS)

    Kleinau, W.; Guerra, L.; Parkinson, R. C.; Lieberherr, J. F.

    1996-02-01

    For future and advanced launch vehicles emphasis is focused on single-stage-to-orbit (SSTO) concepts and on completely reusable versions with the goal to reduce the recurrent launch cost, to improve the mission success probability and also safety for the space transportation of economically attractive payloads into Low Earth Orbit. Both issues, the SSTO launcher and the low cost reusability are extremely challenging and cannot be proven by studies and on-ground tests alone. In-flight demonstration tests are required to verify the assumptions and the new technologies, and to justify the new launcher-and operations-concepts. Because a number of SSTO launch vehicles are currently under discussion in terms of configurations and concepts such as winged vehicles for vertical or horizontal launch and landing (from ground or a flying platform), or wingless vehicles for vertical take-off and landing, and also in terms of propulsion (pure rockets or a combination of air breathing and rocket engines), an experimental demonstrator vehicle appears necessary in order to serve as a pathfinder in this area of multiple challenges. A suborbital Reusable Rocket Launcher Demonstrator (RRLD) has been studied recently by a European industrial team for ESA. This is a multipurpose, evolutionary demonstrator, conceived around a modular approach of incremental improvements of subsystems and materials, to achieve a better propellant mass fraction i.e. a better performance, and specifically for the accomplishment of an incremental flight test programme. While the RRLD basic test programme will acquire knowledge about hypersonic flight, re-entry and landing of a cryogenic rocket propelled launcher — and the low cost reusability (short turnaround on ground) in the utilization programme beyond basic testing, the RRLD will serve as a test bed for generic testing of technologies required for the realization of an SSTO launcher. This paper will present the results of the European RRLD study which

  20. A Unified Global Reference Frame of Vertical Crustal Movements by Satellite Laser Ranging

    PubMed Central

    Zhu, Xinhui; Wang, Ren; Sun, Fuping; Wang, Jinling

    2016-01-01

    Crustal movement is one of the main factors influencing the change of the Earth system, especially in its vertical direction, which affects people’s daily life through the frequent occurrence of earthquakes, geological disasters, and so on. In order to get a better study and application of the vertical crustal movement, as well as its changes, the foundation and prerequisite areto devise and establish its reference frame; especially, a unified global reference frame is required. Since SLR (satellite laser ranging) is one of the most accurate space techniques for monitoring geocentric motion and can directly measure the ground station’s geocentric coordinates and velocities relative to the centre of the Earth’s mass, we proposed to take the vertical velocity of the SLR technique in the ITRF2008 framework as the reference frame of vertical crustal motion, which we defined as the SLR vertical reference frame (SVRF). The systematic bias between other velocity fields and the SVRF was resolved by using the GPS (Global Positioning System) and VLBI (very long baseline interferometry) velocity observations, and the unity of other velocity fields and SVRF was realized, as well. The results show that it is feasible and suitable to take the SVRF as a reference frame, which has both geophysical meanings and geodetic observations, so we recommend taking the SLR vertical velocity under ITRF2008 as the global reference frame of vertical crustal movement. PMID:26867197

  1. Observations of vertical velocities in the tropical upper troposphere and lower stratosphere using the Arecibo 430-MHz radar

    NASA Technical Reports Server (NTRS)

    Cornish, C. R.

    1988-01-01

    The first clear-air observations of vertical velocities in the tropical upper troposphere and lower stratosphere (8-22 km) using the Arecibo 430-MHz radar are presented. Oscillations in the vertical velocity near the Brunt-Vaisala period are observed in the lower stratosphere during the 12-hour observation period. Frequency power spectra from the vertical velocity time series show a slope between -0.5 and -1.0. Vertical wave number spectra computed from the height profiles of vertical velocities have slopes between -1.0 and -1.5. These observed slopes do not agree well with the slopes of +1/3 and -2.5 for frequency and vertical wave number spectra, respectively, predicted by a universal gravity-wave spectrum model. The spectral power of wave number spectra of a radial beam directed 15 deg off-zenith is enhanced by an order of magnitude over the spectral power levels of the vertical beam. This enhancement suggests that other geophysical processes besides gravity waves are present in the horizontal flow. The steepening of the wave number spectrum of the off-vertical beam in the lower stratosphere to near -2.0 is attributed to a quasi-inertial period wave, which was present in the horizontal flow during the observation period.

  2. Trade-off between water pollution prevention, agriculture profit, and farmer practice--an optimization methodology for discussion on land-use adjustment in China.

    PubMed

    Liu, Jianchang; Zhang, Luoping; Zhang, Yuzhen; Deng, Hongbing

    2015-01-01

    Agricultural decision-making to control nonpoint source (NPS) water pollution may not be efficiently implemented, if there is no appropriate cost-benefit analysis on agricultural management practices. This paper presents an interval-fuzzy linear programming (IFLP) model to deal with the trade-off between agricultural revenue, NPS pollution control, and alternative practices through land adjustment for Wuchuan catchment, a typical agricultural area in Jiulong River watershed, Fujian Province of China. From the results, the lower combination of practice 1, practice 2, practice 3, and practice 7 with the land area of 12.6, 5.2, 145.2, and 85.3 hm(2), respectively, could reduce NPS pollution load by 10%. The combination yields an income of 98,580 Chinese Yuan/a. If the pollution reduction is 15%, the higher combination need practice 1, practice 2, practice 3, practice 5, and practice 7 with the land area of 54.4, 23.6, 18.0, 6.3, and 85.3 hm(2), respectively. The income of this combination is 915,170 Chinese Yuan/a. The sensitivity analysis of IFLP indicates that the cost-effective practices are ranked as follows: practice 7 > practice 2 > practice 1 > practice 5 > practice 3 > practice 6 > practice 4. In addition, the uncertainties in the agriculture NPS pollution control system could be effectively quantified by the IFLP model. Furthermore, to accomplish a reasonable and applicable project of land-use adjustment, decision-makers could also integrate above solutions with their own experience and other information.

  3. Graphical analysis of evolutionary trade-off in sylvatic Trypanosoma cruzi transmission modes.

    PubMed

    Kribs-Zaleta, Christopher M

    2014-07-21

    The notion of evolutionary trade-off (one attribute increasing at the expense of another) is central to the evolution of traits, well-studied especially in life-history theory, where a framework first developed by Levins illustrates how internal (genetics) and external (fitness landscapes) forces interact to shape an organism׳s ongoing adaptation. This manuscript extends this framework to the context of vector-borne pathogens, with the example of Trypanosoma cruzi (the etiological agent of Chagas׳ disease) adapting via trade-off among three different infection routes to hosts-stercorarian, vertical, and oral-in response to an epidemiological landscape that involves both hosts and vectors (where, in particular, parasite evolution depends not on parasite density but on relative host and vector densities). Using a fitness measure derived from an invasion reproductive number, this study analyzes several different trade-off scenarios in cycles involving raccoons or woodrats, including a proper three-way trade-off (two independent parameters). Results indicate that selection favors oral transmission to raccoons but classical stercorarian transmission to woodrats even under the same predation rate, with vertical (congenital) transmission favored only when aligned with dominant oral transmission or (at trace levels) under a weak (convex) trade-off. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Anthropometry as a predictor of vertical jump heights derived from an instrumented platform.

    PubMed

    Caruso, John F; Daily, Jeremy S; Mason, Melissa L; Shepherd, Catherine M; McLagan, Jessica R; Marshall, Mallory R; Walker, Ron H; West, Jason O

    2012-01-01

    The current study purpose examined the vertical height-anthropometry relationship with jump data obtained from an instrumented platform. Our methods required college-aged (n = 177) subjects to make 3 visits to our laboratory to measure the following anthropometric variables: height, body mass, upper arm length (UAL), lower arm length, upper leg length, and lower leg length. Per jump, maximum height was measured in 3 ways: from the subjects' takeoff, hang times, and as they landed on the platform. Standard multivariate regression assessed how well anthropometry predicted the criterion variance per gender (men, women, pooled) and jump height method (takeoff, hang time, landing) combination. Z-scores indicated that small amounts of the total data were outliers. The results showed that the majority of outliers were from jump heights calculated as women landed on the platform. With the genders pooled, anthropometry predicted a significant (p < 0.05) amount of variance from jump heights calculated from both takeoff and hang time. The anthropometry-vertical jump relationship was not significant from heights calculated as subjects landed on the platform, likely due to the female outliers. Yet anthropometric data of men did predict a significant amount of variance from heights calculated when they landed on the platform; univariate correlations of men's data revealed that UAL was the best predictor. It was concluded that the large sample of men's data led to greater data heterogeneity and a higher univariate correlation. Because of our sample size and data heterogeneity, practical applications suggest that coaches may find our results best predict performance for a variety of college-aged athletes and vertical jump enthusiasts.

  5. RSRA vertical drag test report. [rotor systems research aircraft

    NASA Technical Reports Server (NTRS)

    Flemming, R. J.

    1981-01-01

    The Rotor Systems Research Aircraft (RSRA), because of its ability to measure rotor loads, was used to conduct an experiment to determine vertical drag, tail rotor blockage, and thrust augmentation as affected by ground clearance and flight velocity. The RSRA was flown in the helicopter configuration at speeds from 0 to 15 knots for wheel heights from 5 to 150 feet, and to 60 knots out of ground effect. The vertical drag trends in hover, predicted by theory and shown in model tests, were generally confirmed. The OGE hover vertical drag is 4.0 percent, 1.1 percent greater than predicted. The vertical drag decreases rapidly as wheel height is reduced, and is zero at a wheel height of 6 feet. The vertical drag also decreases with forward speed, approaching zero at sixty knots. The test data show the effect of wheel height and forward speed on thrust, gross weight capability, and power, and provide the relationships for power and collective pitch at constant gross weight required for the simulation of helicopter takeoffs and landings.

  6. 14 CFR 77.21 - Scope.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... airports having defined strips or pathways that are used regularly for the taking off and landing of... takeoff area with no defined pathways for the landing and taking off of aircraft, a determination shall be... pathways. Those pathways so determined shall be considered runways and an appropriate primary surface as...

  7. Abnormal landing strategies after ACL reconstruction.

    PubMed

    Gokeler, A; Hof, A L; Arnold, M P; Dijkstra, P U; Postema, K; Otten, E

    2010-02-01

    The objective was to analyze muscle activity and movement patterns during landing of a single leg hop for distance after anterior cruciate ligament (ACL) reconstruction. Nine (six males, three females) ACL-reconstructed patients 6 months after surgery and 11 (eight males, three females) healthy control subjects performed the hop task. Electromyographic signals from lower limb muscles were analyzed to determine onset time before landing. Biomechanical data were collected using an Optotrak Motion Analysis System and force plate. Matlab was used to calculate kinetics and joint kinematics. Side-to-side differences in ACL-reconstructed patients and healthy subjects as well as differences between the patients and control group were analyzed. In ACL-reconstructed limbs, significantly earlier onset times were found for all muscles, except vastus medialis, compared with the uninvolved side. The involved limbs had significantly reduced knee flexion during the take-off and increased plantarflexion at initial contact. The knee extension moment was significantly lower in the involved limb. In the control group, significantly earlier onset times were found for the semitendinosus, vastus lateralis and medial gastrocnemius of the non-dominant side compared with the dominant side. Muscle onset times are earlier and movement patterns are altered in the involved limb 6 months after ACL reconstruction.

  8. GPS Vertical Land Motion Corrections to Sea-Level Rise Estimates in the Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Montillet, J.-P.; Melbourne, T. I.; Szeliga, W. M.

    2018-02-01

    We construct coastal Pacific Northwest profiles of vertical land motion (VLM) known to bias long-term tide-gauge measurements of sea-level rise (SLR) and use them to estimate absolute sea-level rise with respect to Earth's center of mass. Multidecade GPS measurements at 47 coastal stations along the Cascadia subduction zone show VLM varies regionally but smoothly along the Pacific coast and inland Puget Sound with rates ranging from + 4.9 to -1.2 mm/yr. Puget Sound VLM is characterized by uniform subsidence at relatively slow rates of -0.1 to -0.3 mm/yr. Uplift rates of 4.5 mm/yr persist along the western Olympic Peninsula of northwestern Washington State and decrease southward becoming nearly 0 mm/yr south of central coastal Washington through Cape Blanco, Oregon. South of Cape Blanco, uplift increases to 1-2 mm/yr, peaks at 4 mm/yr near Crescent City, California, and returns to zero at Cape Mendocino, California. Using various stochastic noise models, we estimate long-term (˜50 -100 yr) relative sea-level rise rates at 18 coastal Cascadia tide gauges and correct them for VLM. Uncorrected SLR rates are scattered, ranging between -2 mm/yr and + 5 mm/yr with mean 0.52 ± 1.59 mm/yr, whereas correcting for VLM increases the mean value to 1.99 mm/yr and reduces the uncertainty to ± 1.18 mm/yr, commensurate with, but approximately 17% higher than, twentieth century global mean.

  9. Trade-offs across space, time, and ecosystem services

    USGS Publications Warehouse

    Rodriguez, J.P.; Beard, T.D.; Bennett, E.M.; Cumming, Graeme S.; Cork, S.J.; Agard, J.; Dobson, A.P.; Peterson, G.D.

    2006-01-01

    Ecosystem service (ES) trade-offs arise from management choices made by humans, which can change the type, magnitude, and relative mix of services provided by ecosystems. Trade-offs occur when the provision of one ES is reduced as a consequence of increased use of another ES. In some cases, a trade-off may be an explicit choice; but in others, trade-offs arise without premeditation or even awareness that they are taking place. Trade-offs in ES can be classified along three axes: spatial scale, temporal scale, and reversibility. Spatial scale refers to whether the effects of the trade-off are felt locally or at a distant location. Temporal scale refers to whether the effects take place relatively rapidly or slowly. Reversibility expresses the likelihood that the perturbed ES may return to its original state if the perturbation ceases. Across all four Millennium Ecosystem Assessment scenarios and selected case study examples, trade-off decisions show a preference for provisioning, regulating, or cultural services (in that order). Supporting services are more likely to be "taken for granted." Cultural ES are almost entirely unquantified in scenario modeling; therefore, the calculated model results do not fully capture losses of these services that occur in the scenarios. The quantitative scenario models primarily capture the services that are perceived by society as more important - provisioning and regulating ecosystem services - and thus do not fully capture trade-offs of cultural and supporting services. Successful management policies will be those that incorporate lessons learned from prior decisions into future management actions. Managers should complement their actions with monitoring programs that, in addition to monitoring the short-term provisions of services, also monitor the long-term evolution of slowly changing variables. Policies can then be developed to take into account ES trade-offs at multiple spatial and temporal scales. Successful strategies will

  10. The role of Latin America's land and water resources for global food security: environmental trade-offs of future food production pathways.

    PubMed

    Flachsbarth, Insa; Willaarts, Bárbara; Xie, Hua; Pitois, Gauthier; Mueller, Nathaniel D; Ringler, Claudia; Garrido, Alberto

    2015-01-01

    One of humanity's major challenges of the 21st century will be meeting future food demands on an increasingly resource constrained-planet. Global food production will have to rise by 70 percent between 2000 and 2050 to meet effective demand which poses major challenges to food production systems. Doing so without compromising environmental integrity is an even greater challenge. This study looks at the interdependencies between land and water resources, agricultural production and environmental outcomes in Latin America and the Caribbean (LAC), an area of growing importance in international agricultural markets. Special emphasis is given to the role of LAC's agriculture for (a) global food security and (b) environmental sustainability. We use the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT)-a global dynamic partial equilibrium model of the agricultural sector-to run different future production scenarios, and agricultural trade regimes out to 2050, and assess changes in related environmental indicators. Results indicate that further trade liberalization is crucial for improving food security globally, but that it would also lead to more environmental pressures in some regions across Latin America. Contrasting land expansion versus more intensified agriculture shows that productivity improvements are generally superior to agricultural land expansion, from an economic and environmental point of view. Finally, our analysis shows that there are trade-offs between environmental and food security goals for all agricultural development paths.

  11. Analytical solutions to trade-offs between size of protected areas and land-use intensity.

    PubMed

    Butsic, Van; Radeloff, Volker C; Kuemmerle, Tobias; Pidgeon, Anna M

    2012-10-01

    Land-use change is affecting Earth's capacity to support both wild species and a growing human population. The question is how best to manage landscapes for both species conservation and economic output. If large areas are protected to conserve species richness, then the unprotected areas must be used more intensively. Likewise, low-intensity use leaves less area protected but may allow wild species to persist in areas that are used for market purposes. This dilemma is present in policy debates on agriculture, housing, and forestry. Our goal was to develop a theoretical model to evaluate which land-use strategy maximizes economic output while maintaining species richness. Our theoretical model extends previous analytical models by allowing land-use intensity on unprotected land to influence species richness in protected areas. We devised general models in which species richness (with modified species-area curves) and economic output (a Cobb-Douglas production function) are a function of land-use intensity and the proportion of land protected. Economic output increased as land-use intensity and extent increased, and species richness responded to increased intensity either negatively or following the intermediate disturbance hypothesis. We solved the model analytically to identify the combination of land-use intensity and protected area that provided the maximum amount of economic output, given a target level of species richness. The land-use strategy that maximized economic output while maintaining species richness depended jointly on the response of species richness to land-use intensity and protection and the effect of land use outside protected areas on species richness within protected areas. Regardless of the land-use strategy, species richness tended to respond to changing land-use intensity and extent in a highly nonlinear fashion. ©2012 Society for Conservation Biology.

  12. Atmospheric Constraints on Landing Site Selection

    NASA Astrophysics Data System (ADS)

    Kass, David M.; Schofield, J. T.

    2001-01-01

    the landing process, the total velocity (including both the horizontal and vertical components) determines whether or not the landers are successful. Unfortunately, the landing system has no easy way to nullify any horizontal velocity imparted by the wind, so the landing sites selected need to have as little wind as possible. In addition to the mean wind velocity, the landing system is sensitive to vertical wind shear in the lowest kilometer or so. Wind shear can deflect the retro rockets (RADs) from their nominal vertical orientation producing unwanted horizontal spacecraft velocities. Both mean velocity and wind shear are dominated by the the local topography and other surface properties (in particular albedo and thermal inertia which control the surface temperature). This is seen even in simplified 2-D mesoscale models. The effects in a fully 3-D model are expected to he even more topographically dependent. In particular there is potential for wind channeling in canyons and other terrain features. Boundary layer winds and wind shear are currently being modeled based on terrestrial data and boundary layer scaling laws modified for Martian conditions. We hope to supplement this with mesoscale model results (from several sources) once the number of landing sites is reduced to a manageable number.

  13. Lift-fan aircraft: Lessons learned-the pilot's perspective

    NASA Technical Reports Server (NTRS)

    Gerdes, Ronald M.

    1993-01-01

    This paper is written from an engineering test pilot's point of view. Its purpose is to present lift-fan 'lessons learned' from the perspective of first-hand experience accumulated during the period 1962 through 1988 while flight testing vertical/short take-off and landing (V/STOL) experimental aircraft and evaluating piloted engineering simulations of promising V/STOL concepts. Specifically, the scope of the discussions to follow is primarily based upon a critical review of the writer's personal accounts of 30 hours of XV-5A/B and 2 hours of X-14A flight testing as well as a limited simulator evaluation of the Grumman Design 755 lift-fan aircraft. Opinions of other test pilots who flew these aircraft and the aircraft simulator are also included and supplement the writer's comments. Furthermore, the lessons learned are presented from the perspective of the writer's flying experience: 10,000 hours in 100 fixed- and rotary-wing aircraft including 330 hours in 5 experimental V/STOL research aircraft. The paper is organized to present to the reader a clear picture of lift-fan lessons learned from three distinct points of view in order to facilitate application of the lesson principles to future designs. Lessons learned are first discussed with respect to case histories of specific flight and simulator investigations. These principles are then organized and restated with respect to four selected design criteria categories in Appendix I. Lastly, Appendix Il is a discussion of the design of a hypothetical supersonic short take-off vertical landing (STOVL) fighter/attack aircraft.

  14. Helicopter Field Testing of NASA's Autonomous Landing and Hazard Avoidance Technology (ALHAT) System fully Integrated with the Morpheus Vertical Test Bed Avionics

    NASA Technical Reports Server (NTRS)

    Epp, Chirold D.; Robertson, Edward A.; Ruthishauser, David K.

    2013-01-01

    The Autonomous Landing and Hazard Avoidance Technology (ALHAT) Project was chartered to develop and mature to a Technology Readiness Level (TRL) of six an autonomous system combining guidance, navigation and control with real-time terrain sensing and recognition functions for crewed, cargo, and robotic planetary landing vehicles. The ALHAT System must be capable of identifying and avoiding surface hazards to enable a safe and accurate landing to within tens of meters of designated and certified landing sites anywhere on a planetary surface under any lighting conditions. This is accomplished with the core sensing functions of the ALHAT system: Terrain Relative Navigation (TRN), Hazard Detection and Avoidance (HDA), and Hazard Relative Navigation (HRN). The NASA plan for the ALHAT technology is to perform the TRL6 closed loop demonstration on the Morpheus Vertical Test Bed (VTB). The first Morpheus vehicle was lost in August of 2012 during free-flight testing at Kennedy Space Center (KSC), so the decision was made to perform a helicopter test of the integrated ALHAT System with the Morpheus avionics over the ALHAT planetary hazard field at KSC. The KSC helicopter tests included flight profiles approximating planetary approaches, with the entire ALHAT system interfaced with all appropriate Morpheus subsystems and operated in real-time. During these helicopter flights, the ALHAT system imaged the simulated lunar terrain constructed in FY2012 to support ALHAT/Morpheus testing at KSC. To the best of our knowledge, this represents the highest fidelity testing of a system of this kind to date. During this helicopter testing, two new Morpheus landers were under construction at the Johnson Space Center to support the objective of an integrated ALHAT/Morpheus free-flight demonstration. This paper provides an overview of this helicopter flight test activity, including results and lessons learned, and also provides an overview of recent integrated testing of ALHAT on the second

  15. Helicopter Field Testing of NASA's Autonomous Landing and Hazard Avoidance Technology (ALHAT) System fully integrated with the Morpheus Vertical Test Bed Avionics

    NASA Technical Reports Server (NTRS)

    Rutishauser, David; Epp, Chirold; Robertson, Edward

    2013-01-01

    The Autonomous Landing Hazard Avoidance Technology (ALHAT) Project was chartered to develop and mature to a Technology Readiness Level (TRL) of six an autonomous system combining guidance, navigation and control with real-time terrain sensing and recognition functions for crewed, cargo, and robotic planetary landing vehicles. The ALHAT System must be capable of identifying and avoiding surface hazards to enable a safe and accurate landing to within tens of meters of designated and certified landing sites anywhere on a planetary surface under any lighting conditions. This is accomplished with the core sensing functions of the ALHAT system: Terrain Relative Navigation (TRN), Hazard Detection and Avoidance (HDA), and Hazard Relative Navigation (HRN). The NASA plan for the ALHAT technology is to perform the TRL6 closed loop demonstration on the Morpheus Vertical Test Bed (VTB). The first Morpheus vehicle was lost in August of 2012 during free-flight testing at Kennedy Space Center (KSC), so the decision was made to perform a helicopter test of the integrated ALHAT System with the Morpheus avionics over the ALHAT planetary hazard field at KSC. The KSC helicopter tests included flight profiles approximating planetary approaches, with the entire ALHAT system interfaced with all appropriate Morpheus subsystems and operated in real-time. During these helicopter flights, the ALHAT system imaged the simulated lunar terrain constructed in FY2012 to support ALHAT/Morpheus testing at KSC. To the best of our knowledge, this represents the highest fidelity testing of a system of this kind to date. During this helicopter testing, two new Morpheus landers were under construction at the Johnson Space Center to support the objective of an integrated ALHAT/Morpheus free-flight demonstration. This paper provides an overview of this helicopter flight test activity, including results and lessons learned, and also provides an overview of recent integrated testing of ALHAT on the second

  16. 36 CFR 242.27 - Subsistence taking of fish.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 2 2013-07-01 2013-07-01 false Subsistence taking of fish. 242.27 Section 242.27 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE SUBSISTENCE MANAGEMENT REGULATIONS FOR PUBLIC LANDS IN ALASKA Subsistence Taking of Fish and Wildlife § 242.27 Subsistence taking of fish. (a)...

  17. 36 CFR 242.27 - Subsistence taking of fish.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 2 2012-07-01 2012-07-01 false Subsistence taking of fish. 242.27 Section 242.27 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE SUBSISTENCE MANAGEMENT REGULATIONS FOR PUBLIC LANDS IN ALASKA Subsistence Taking of Fish and Wildlife § 242.27 Subsistence taking of fish. (a)...

  18. 36 CFR 242.27 - Subsistence taking of fish.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 2 2014-07-01 2014-07-01 false Subsistence taking of fish. 242.27 Section 242.27 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE SUBSISTENCE MANAGEMENT REGULATIONS FOR PUBLIC LANDS IN ALASKA Subsistence Taking of Fish and Wildlife § 242.27 Subsistence taking of fish. (a)...

  19. 36 CFR 242.27 - Subsistence taking of fish.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 2 2011-07-01 2011-07-01 false Subsistence taking of fish. 242.27 Section 242.27 Parks, Forests, and Public Property FOREST SERVICE, DEPARTMENT OF AGRICULTURE SUBSISTENCE MANAGEMENT REGULATIONS FOR PUBLIC LANDS IN ALASKA Subsistence Taking of Fish and Wildlife § 242.27 Subsistence taking of fish. (a)...

  20. Recent UAS Developments: VTOL HQ-series Shipboard Recovery and Autonomous Monitoring with MicroQuads

    NASA Astrophysics Data System (ADS)

    Wardell, L. J.; Farber, A. M.; Douglas, J.

    2017-12-01

    Ocean research would benefit from reliable shipboard launch and recovery of small class UAS. The vertical take-off and landing (VTOL) system reduces equipment footprint without the need for launchers or recovery systems. The HQ-60 (Latitude Engineering) has demonstrated reliable ship take-off and recovery on a 10x10' area on the R/V Falkor (Schmidt Ocean Institute) and other research vessels. The HQ-60 recently set a record for longest time aloft for a VTOL aircraft, flying nearly 22.5 hours non-stop. To support close-range research, autonomous MicroQuads that "perch" in a protective box that also recharges the aircraft and transmits the data is in development. Recent MicroQuad work with developing high-resolution (<1cm) DEMs using on-board cameras has yielded promising results for the use of surface change detection. Recent USDA development targeted erosion monitoring with this system. The latest updates and testing results for both systems will be presented.

  1. 50 CFR 622.276 - Landing fish intact.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 12 2013-10-01 2013-10-01 false Landing fish intact. 622.276 Section 622... Wahoo Fishery Off the Atlantic States § 622.276 Landing fish intact. (a) Dolphin and wahoo in or from the Atlantic EEZ must be maintained with head and fins intact. Such fish may be eviscerated, gilled...

  2. 50 CFR 622.276 - Landing fish intact.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 50 Wildlife and Fisheries 12 2014-10-01 2014-10-01 false Landing fish intact. 622.276 Section 622... Wahoo Fishery Off the Atlantic States § 622.276 Landing fish intact. (a) Dolphin and wahoo in or from the Atlantic EEZ must be maintained with head and fins intact. Such fish may be eviscerated, gilled...

  3. The NASA landing gear test airplane

    NASA Technical Reports Server (NTRS)

    Carter, John F.; Nagy, Christopher J.

    1995-01-01

    A tire and landing gear test facility has been developed and incorporated into a Convair 990 aircraft. The system can simulate tire vertical load profiles to 250,000 lb, sideslip angles to 15 degrees, and wheel braking on actual runways. Onboard computers control the preprogrammed test profiles through a feedback loop and also record three axis loads, tire slip angle, and tire condition. The aircraft to date has provided tire force and wear data for the Shuttle Orbiter tire on three different runways and at east and west coast landing sites. This report discusses the role of this facility in complementing existing ground tire and landing gear test facilities, and how this facility can simultaneously simulate the vertical load, tire slip, velocity, and surface for an entire aircraft landing. A description is given of the aircraft as well as the test system. An example of a typical test sequence is presented. Data collection and reduction from this facility are discussed, as well as accuracies of calculated parameters. Validation of the facility through ground and flight tests is presented. Tests to date have shown that this facility can operate at remote sites and gather complete data sets of load, slip, and velocity on actual runway surfaces. The ground and flight tests have led to a successful validation of this test facility.

  4. 78 FR 36691 - Airworthiness Directives; Piaggio Aero Industries S.p.A Airplanes

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-19

    ... that the cracks were initiated by an unforeseen friction in the MLG wheel lever sub-assembly. This... in loss of control of the aeroplane during take-off or landing runs. To address this potential unsafe... loss of control during take-off or landing runs. (f) Actions and Compliance Unless already done, do the...

  5. Taking off

    ERIC Educational Resources Information Center

    Gorman, Elizabeth

    2012-01-01

    With roots going back to 1986, the Student Team on Alumni Relations or STAR was one of the first student-alumni groups in Canada and routinely attracted capable and enthusiastic volunteers. It offered to appreciative, albeit small, student audiences a suite of popular programs, including job shadowing and goodie boxes parents could send to their…

  6. Sex differences in lower extremity biomechanics during single leg landings.

    PubMed

    Schmitz, Randy J; Kulas, Anthony S; Perrin, David H; Riemann, Bryan L; Shultz, Sandra J

    2007-07-01

    Females have an increased incident rate of anterior cruciate ligament tears compared to males. Biomechanical strategies to decelerate the body in the vertical direction have been implicated as a contributing cause. This study determined if females would exhibit single leg landing strategies characterized by decreased amounts of hip, knee, and ankle flexion resulting in greater vertical ground reaction forces and altered energy absorption patterns when compared to males. Recreationally active males (N=14) and females (N=14), completed five single leg landings from a 0.3m height onto a force platform while three-dimensional kinematics and kinetics were simultaneously collected. Compared to males, females exhibited (1) less total hip and knee flexion displacements (40% and 64% of males, respectively, P<0.05) and less time to peak hip and knee flexion (48% and 78% of males, respectively, P<0.05), (2) 9% greater peak vertical ground reaction forces (P<0.05), (3) less total lower body energy absorption (76% of males, P<0.05), and (4) 11% greater relative energy absorption at the ankle (P<0.05). Females in this study appear to adopt a single leg landing style using less hip and knee flexion, absorbing less total lower body energy with more relative energy at the ankle resulting in a landing style that can be described as stiff. This may potentially cause increased demands on non-contractile components of the lower extremity. Preventative training programs designed to prevent knee injury may benefit from the biomechanical description of sex-specific landing methods demonstrated by females in this study by focusing on the promotion of more reliance on using the contractile components to absorb impact energy during landings.

  7. Do submesoscale frontal processes ventilate the oxygen minimum zone off Peru?

    NASA Astrophysics Data System (ADS)

    Thomsen, S.; Kanzow, T.; Colas, F.; Echevin, V.; Krahmann, G.; Engel, A.

    2016-02-01

    The Peruvian upwelling region shows pronounced near-surface submesoscale variability including filaments and sharp density fronts. Submesoscale frontal processes can drive large vertical velocities and enhance vertical tracer fluxes in the upper ocean. The associated high temporal and spatial variability poses a large challenge to observational approaches targeting these processes. In this study the role of submesoscale processes for the ventilation of the near-coastal oxygen minimum zone off Peru is investigated. We use satellite based sea surface temperature measurements and multiple high-resolution glider observations of temperature, salinity, oxygen and chlorophyll fluorescence carried out in January and February 2013 off Peru near 14°S during active upwelling. Additionally, high-resolution regional ocean circulation model outputs (ROMS) outputs are analysed. At the beginning of our observational survey a previously upwelled, productive and highly oxygenated water body is found in the mixed layer. Subsequently, a cold filament forms and the waters are moved offshore. After the decay of the filament and the relaxation of the upwelling front, the oxygen enriched surface water is found in the previously less oxygenated thermocline suggesting the occurrence of frontal subduction. A numerical model simulation is used to analyse the evolution of Lagrangian numerical floats in several upwelling filaments, whose vertical structure and hydrographic properties agree well with the observations. The floats trajectories support our interpretation that the subduction of previously upwelled water occurs in filaments off Peru. We find that 40 - 60 % of the floats seeded in the newly upwelled water is subducted within a time period of 5 days. This hightlights the importance of this process in ventilating the oxycline off Peru.

  8. Evaluating the networking characteristics of the Cray XC-40 Intel Knights Landing-based Cori supercomputer at NERSC

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

    Doerfler, Douglas; Austin, Brian; Cook, Brandon

    There are many potential issues associated with deploying the Intel Xeon Phi™ (code named Knights Landing [KNL]) manycore processor in a large-scale supercomputer. One in particular is the ability to fully utilize the high-speed communications network, given that the serial performance of a Xeon Phi TM core is a fraction of a Xeon®core. In this paper, we take a look at the trade-offs associated with allocating enough cores to fully utilize the Aries high-speed network versus cores dedicated to computation, e.g., the trade-off between MPI and OpenMP. In addition, we evaluate new features of Cray MPI in support of KNL,more » such as internode optimizations. We also evaluate one-sided programming models such as Unified Parallel C. We quantify the impact of the above trade-offs and features using a suite of National Energy Research Scientific Computing Center applications.« less

  9. 7. Close view of the lower portion of vertical sign ...

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

    7. Close view of the lower portion of vertical sign with the letters "A-G-O" after removal from theatre (Note: the steel I-beam was inserted and sheet metal side panels taken off to facilitate removal from theatre - Chicago Theater, 175 North State Street, Chicago, Cook County, IL

  10. Estimating snow water equivalent from GPS vertical site-position observations in the western United States

    PubMed Central

    Ouellette, Karli J; de Linage, Caroline; Famiglietti, James S

    2013-01-01

    [1] Accurate estimation of the characteristics of the winter snowpack is crucial for prediction of available water supply, flooding, and climate feedbacks. Remote sensing of snow has been most successful for quantifying the spatial extent of the snowpack, although satellite estimation of snow water equivalent (SWE), fractional snow covered area, and snow depth is improving. Here we show that GPS observations of vertical land surface loading reveal seasonal responses of the land surface to the total weight of snow, providing information about the stored SWE. We demonstrate that the seasonal signal in Scripps Orbit and Permanent Array Center (SOPAC) GPS vertical land surface position time series at six locations in the western United States is driven by elastic loading of the crust by the snowpack. GPS observations of land surface deformation are then used to predict the water load as a function of time at each location of interest and compared for validation to nearby Snowpack Telemetry observations of SWE. Estimates of soil moisture are included in the analysis and result in considerable improvement in the prediction of SWE. Citation: Ouellette, K. J., C. de Linage, and J. S. Famiglietti (2013), Estimating snow water equivalent from GPS vertical site-position observations in the western United States, Water Resour. Res., 49, 2508–2518, doi:10.1002/wrcr.20173. PMID:24223442

  11. Landing impact studies of a 0.3-scale model air cushion landing system for a Navy fighter airplane

    NASA Technical Reports Server (NTRS)

    Leland, T. J. W.; Thompson, W. C.

    1975-01-01

    An experimental study was conducted in order to determine the landing-impact behavior of a 0.3-scale, dynamically (but not physically) similar model of a high-density Navy fighter equipped with an air cushion landing system. The model was tested over a range of landing contact attitudes at high forward speeds and sink rates on a specialized test fixture at the Langley aircraft landing loads and traction facility. The investigation indicated that vertical acceleration at landing impact was highly dependent on the pitch angle at ground contact, the higher acceleration of approximately 5g occurring near zero body-pitch attitude. A limited number of low-speed taxi tests were made in order to determine model stability characteristics. The model was found to have good pitch-damping characteristics but stability in roll was marginal.

  12. 50 CFR 217.172 - Permissible methods of taking.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 50 Wildlife and Fisheries 10 2013-10-01 2013-10-01 false Permissible methods of taking. 217.172 Section 217.172 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC... Neptune Liquefied Natural Gas Facility Off Massachusetts § 217.172 Permissible methods of taking. (a...

  13. 50 CFR 217.172 - Permissible methods of taking.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Permissible methods of taking. 217.172 Section 217.172 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC... Neptune Liquefied Natural Gas Facility Off Massachusetts § 217.172 Permissible methods of taking. (a...

  14. Real-time simulation of an F110/STOVL turbofan engine

    NASA Technical Reports Server (NTRS)

    Drummond, Colin K.; Ouzts, Peter J.

    1989-01-01

    A traditional F110-type turbofan engine model was extended to include a ventral nozzle and two thrust-augmenting ejectors for Short Take-Off Vertical Landing (STOVL) aircraft applications. Development of the real-time F110/STOVL simulation required special attention to the modeling approach to component performance maps, the low pressure turbine exit mixing region, and the tailpipe dynamic approximation. Simulation validation derives by comparing output from the ADSIM simulation with the output for a validated F110/STOVL General Electric Aircraft Engines FORTRAN deck. General Electric substantiated basic engine component characteristics through factory testing and full scale ejector data.

  15. High-Fidelity Computational Aerodynamics of the Elytron 4S UAV

    NASA Technical Reports Server (NTRS)

    Ventura Diaz, Patricia; Yoon, Seokkwan; Theodore, Colin R.

    2018-01-01

    High-fidelity Computational Fluid Dynamics (CFD) have been carried out for the Elytron 4S Unmanned Aerial Vehicle (UAV), also known as the converticopter "proto12". It is the scaled wind tunnel model of the Elytron 4S, an Urban Air Mobility (UAM) concept, a tilt-wing, box-wing rotorcraft capable of Vertical Take-Off and Landing (VTOL). The three-dimensional unsteady Navier-Stokes equations are solved on overset grids employing high-order accurate schemes, dual-time stepping, and a hybrid turbulence model using NASA's CFD code OVERFLOW. The Elytron 4S UAV has been simulated in airplane mode and in helicopter mode.

  16. Should you take your brand to where the action is?

    PubMed

    Aaker, D A

    1997-01-01

    When markets turn hostile, it's no surprise that managers are tempted to extend their brands vertically--that is, to take their brands into a seemingly attractive market above or below their current positions. And for companies chasing growth, the urge to move into booming premium or value segments also can be hard to resist. The draw is indeed strong; and in some instances, a vertical move is not merely justified but actually essential to survival--even for top brands, which have the advantages of economies of scale, brand equity, and retail clout. But beware: leveraging a brand to access upscale or downscale markets is more dangerous than it first appears. Before making a move, then, managers should ascertain whether the rewards will be worth the risks. In general, David Aaker recommends that managers avoid vertical extensions whenever possible. There is an inherent contradiction in the very concept because brand equity is built in large part on image and perceived worth, and a vertical move can easily distort those qualities. Still, certain situations demand vertical extensions, and Aaker examines both the winners and the losers in the game. Managers may find themselves facing a situation that presents both an emerging opportunity and a strategic threat, and alternatives to vertical extensions may have even higher risks and costs. Furthermore, a number of brands have been extended vertically with complete success. If after assessing the risks and rewards you conclude that a vertical extension is on the horizon, proceed with caution. And keep in mind that your challenge will be to leverage and protect the original brand while taking advantage of the new opportunity.

  17. Sulfur plumes off Namibia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Sulfur plumes rising up from the bottom of the ocean floor produce colorful swirls in the waters off the coast of Namibia in southern Africa. The plumes come from the breakdown of marine plant matter by anaerobic bacteria that do not need oxygen to live. This image was acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite on April 24, 2002 Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  18. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with the...

  19. 14 CFR 29.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with the...

  20. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with the...

  1. 14 CFR 27.501 - Ground loading conditions: landing gear with skids.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ...) The ground reactions rationally distributed along the bottom of the skid tube. (b) Vertical reactions... along the bottom of both skids, the vertical reactions must be applied as prescribed in paragraph (a) of this section. (c) Drag reactions in the level landing attitude. In the level attitude, and with the...

  2. Pilot investigation - Nominal crew induced forces in zero-g

    NASA Technical Reports Server (NTRS)

    Klute, Glenn K.

    1992-01-01

    This report presents pilot-study data of test subject forces induced by intravehicular activities such as push-offs and landings with both hands and feet. Five subjects participated in this investigation. Three orthogonal force axes were measured in the NASA KC-135 research aircraft's 'zero-g' environment. The largest forces were induced during vertical foot push-offs, including one of 534 newtons (120 lbs). The mean vertical foot push-off was 311 newtons (70 lbs). The vertical hand push-off forces were also relatively large, including one of 267 newtons (60 lbs) with a mean of 151 newtons (34 lbs). These force magnitudes of these forces would result in a Shuttle gravity environment of about 1 x exp 10 -4 g's.

  3. Landing gear energy absorption system

    NASA Technical Reports Server (NTRS)

    Hansen, Christopher P. (Inventor)

    1994-01-01

    A landing pad system is described for absorbing horizontal and vertical impact forces upon engagement with a landing surface where circumferentially arranged landing struts respectively have a clevis which receives a slidable rod member and where the upper portion of a slidable rod member is coupled to the clevis by friction washers which are force fit onto the rod member to provide for controlled constant force energy absorption when the rod member moves relative to the clevis. The lower end of the friction rod is pivotally attached by a ball and socket to a support plate where the support plate is arranged to slide in a transverse direction relative to a housing which contains an energy absorption material for absorbing energy in a transverse direction.

  4. Prophylactic Ankle Braces and the Kinematics and Kinetics of Half-Squat Parachute Landing.

    PubMed

    Wu, Di; Zheng, Chao; Wu, Ji; Hu, Tan; Huang, Rongrong; Wang, Lizhen; Fan, Yubo

    2018-02-01

    The objective of the study was to investigate the effects of dropping heights and prophylactic ankle braces on ankle joint biomechanics during half-squat parachute landing from two different heights. There were 30 male elite paratroopers with formal parachute landing training and more than 2 yr of parachute jumping experience who were recruited for this study. The subjects tested three different ankle brace conditions (no-brace, elastic brace, semirigid brace). Each subject was instructed to jump off a platform from two different heights of 0.4 m and 0.8 m, and land on a force plate in a half-squat posture. The Vicon 3D motion capture system and force plate were used to record and calculate kinematic and kinetic data. Dropping height had a significant effect on peak vertical ground reaction force (vGRF), maximum ankle angular displacement, and time to vGRF. As compared with the no-brace group, use of an elastic ankle brace significantly reduced peak vGRF by 18.57% and both braces significantly reduced the maximal angular displacements of dorsiflexion. The semirigid brace provided greater restriction against maximal angular displacement of inversion. The elastic and semirigid ankle braces both effectively restricted motion stability of the ankle joint in the sagittal plane, and the semirigid ankle brace prevented excessive inversion, although the comfort of this device should be improved overall.Wu D, Zheng C, Wu J, Hu T, Huang R, Wang L, Fan Y. Prophylactic ankle braces and the kinematics and kinetics of half-squat parachute landing. Aerosp Med Hum Perform. 2018; 89(2):141-146.

  5. Managing the global land resource.

    PubMed

    Smith, Pete

    2018-03-14

    With a growing population with changing demands, competition for the global land resource is increasing. We need to feed a projected population of 9-10 billion by 2050, rising to approximately 12 billion by 2100. At the same time, we need to reduce the climate impact of agriculture, forestry and other land use, and we almost certainly need to deliver land-based greenhouse gas removal for additional climate change mitigation. In addition, we need to deliver progress towards meeting the United Nations Sustainable Development Goals, all without compromising the many ecosystem services provided by land and without exceeding planetary boundaries. Managing the land to tackle these pressing issues is a major global challenge. In this perspective paper, I provide a very broad overview of the main challenges, and explore co-benefits, trade-offs and possible solutions. © 2018 The Authors.

  6. Managing the global land resource

    PubMed Central

    2018-01-01

    With a growing population with changing demands, competition for the global land resource is increasing. We need to feed a projected population of 9–10 billion by 2050, rising to approximately 12 billion by 2100. At the same time, we need to reduce the climate impact of agriculture, forestry and other land use, and we almost certainly need to deliver land-based greenhouse gas removal for additional climate change mitigation. In addition, we need to deliver progress towards meeting the United Nations Sustainable Development Goals, all without compromising the many ecosystem services provided by land and without exceeding planetary boundaries. Managing the land to tackle these pressing issues is a major global challenge. In this perspective paper, I provide a very broad overview of the main challenges, and explore co-benefits, trade-offs and possible solutions. PMID:29514961

  7. Vertical and lateral flux on the continental slope off Pakistan: correlation of sediment core and trap results

    NASA Astrophysics Data System (ADS)

    Schulz, H.; von Rad, U.

    2014-06-01

    Due to the lack of bioturbation, the varve-laminated muds from the oxygen minimum zone (OMZ) off Pakistan provide a unique opportunity to precisely determine the vertical and lateral sediment fluxes in the nearshore part of the northeastern Arabian Sea. West of Karachi (Hab area), the results of two sediment trap stations (EPT and WPT) were correlated with 16 short sediment cores on a depth transect crossing the OMZ. The top of a distinct, either reddish- or light-gray silt layer, 210Pb-dated as AD 1905 ± 10, was used as an isochronous stratigraphic marker bed to calculate sediment accumulation rates. In one core, the red and gray layer were separated by a few (5-10) thin laminae. According to our varve model, this contributes < 10 years to the dating uncertainty, assuming that the different layers are almost synchronous. We directly compared the accumulation rates with the flux rates from the sediment traps that collected the settling material within the water column above. All traps on the steep Makran continental slope show exceptionally high, pulsed winter fluxes of up to 5000 mg m-2 d-1. Based on core results, the flux at the seafloor amounts to 4000 mg m-2 d-1 and agrees remarkably well with the bulk winter flux of material, as well as with the flux of the individual bulk components of organic carbon, calcium carbonate and opal. However, due to the extreme mass of remobilized matter, the high winter flux events exceeded the capacity of the shallow traps. Based on our comparisons, we argue that high-flux events must occur regularly during winter within the upper OMZ off Pakistan to explain the high accumulations rates. These show distribution patterns that are a negative function of water depth and distance from the shelf. Some of the sediment fractions show marked shifts in accumulation rates near the lower boundary of the OMZ. For instance, the flux of benthic foraminifera is lowered but stable below ~1200-1300 m. However, flux and sedimentation in the

  8. Reframing the land-sparing/land-sharing debate for biodiversity conservation.

    PubMed

    Kremen, Claire

    2015-10-01

    Conservation biologists are devoting an increasing amount of energy to debating whether land sparing (high-yielding agriculture on a small land footprint) or land sharing (low-yielding, wildlife-friendly agriculture on a larger land footprint) will promote better outcomes for local and global biodiversity. In turn, concerns are mounting about how to feed the world, given increasing demands for food. In this review, I evaluate the land-sparing/land-sharing framework--does the framework stimulate research and policy that can reconcile agricultural land use with biodiversity conservation, or is a revised framing needed? I review (1) the ecological evidence in favor of sparing versus sharing; (2) the evidence from land-use change studies that assesses whether a relationship exists between agricultural intensification and land sparing; and (3) how that relationship may be affected by socioeconomic and political factors. To address the trade-off between biodiversity conservation and food production, I then ask which forms of agricultural intensification can best feed the world now and in the future. On the basis of my review, I suggest that the dichotomy of the land-sparing/land-sharing framework limits the realm of future possibilities to two, largely undesirable, options for conservation. Both large, protected regions and favorable surrounding matrices are needed to promote biodiversity conservation; they work synergistically and are not mutually exclusive. A "both-and" framing of large protected areas surrounded by a wildlife-friendly matrix suggests different research priorities from the "either-or" framing of sparing versus sharing. Furthermore, wildlife-friendly farming methods such as agroecology may be best adapted to provide food for the world's hungry people. © 2015 New York Academy of Sciences.

  9. Landing Characteristics of the Apollo Spacecraft with Deployed Heat Shield Impact Attenuation Systems

    NASA Technical Reports Server (NTRS)

    Stubbs, Sandy M.

    1965-01-01

    An experimental investigation was made to determine the landing characteristics of a 1/4-scale dynamic model of the Apollo spacecraft command module using two different active (heat shield deployed prior to landing) landing systems for impact attenuation. One landing system (configuration 1) consisted of six hydraulic struts and eight crushable honeycomb struts. The other landing system (configuration 2), consisted of four hydraulic struts and six strain straps. Tests made on water and the hard clay-gravel composite landing surfaces simulated parachute letdown (vertical) velocities of 23 ft/sec (7.0 m/s) (full scale). Landings made on the sand landing surface simulated vertical velocities of 30 ft/sec (9.1 m/s). Horizontal velocities of from 0 to 50 ft/sec (15 m/s) were simulated. Landing attitudes ranged from -30'degrees to 20 degrees, and the roll attitudes were O degrees, 90 degrees, and 180 degrees. For configuration 1, maximum normal accelerations at the vehicle center of gravity for landings on water, sand, and the hard clay-gravel composite surface were 9g, 20g, and 18g, respectively. The maximum normal center-of-gravity acceleration for configuration 2 which was landed only on the hard clay-gravel landing surface was approximately 19g. Accelerations for configuration 2 were generally equal to or lower than accelerations for configuration 1 and normal.

  10. Modelling the long-term vertical dynamics of salt marshes

    NASA Astrophysics Data System (ADS)

    Zoccarato, Claudia; Teatini, Pietro

    2017-04-01

    Salt marshes are vulnerable environments hosting complex interactions between physical and biological processes with a strong influence on the dynamics of the marsh evolution. The estimation and prediction of the elevation of a salt-marsh platform is crucial to forecast the marsh growth or regression under different scenarios considering, for example, the potential climate changes. The long-term vertical dynamics of a salt marsh is predicted with the aid of an original finite-element (FE) numerical model accounting for the marsh accretion and compaction and for the variation rates of the relative sea level rise, i.e., land subsidence of the marsh basement and eustatic rise of the sea level. The accretion term considers the vertical sedimentation of organic and inorganic material over the marsh surface, whereas the compaction reflects the progressive consolidation of the porous medium under the increasing load of the overlying younger deposits. The modelling approach is based on a 2D groundwater flow simulator, which provides the pressure evolution within a compacting/accreting vertical cross-section of the marsh assuming that the groundwater flow obeys the relative Darcy's law, coupled to a 1D vertical geomechanical module following Terzaghi's principle of effective intergranular stress. Soil porosity, permeability, and compressibility may vary with the effective intergranular stress according to empirically based relationships. The model also takes into account the geometric non-linearity arising from the consideration of large solid grain movements by using a Lagrangian approach with an adaptive FE mesh. The element geometry changes in time to follow the deposit consolidation and the element number increases in time to follow the sedimentation of new material. The numerical model is tested on different realistic configurations considering the influence of (i) the spatial distribution of the sedimentation rate in relation to the distance from the marsh margin, (ii

  11. The Revolutionary Vertical Lift Technology (RVLT) Project

    NASA Technical Reports Server (NTRS)

    Yamauchi, Gloria K.

    2018-01-01

    The Revolutionary Vertical Lift Technology (RVLT) Project is one of six projects in the Advanced Air Vehicles Program (AAVP) of the NASA Aeronautics Research Mission Directorate. The overarching goal of the RVLT Project is to develop and validate tools, technologies, and concepts to overcome key barriers for vertical lift vehicles. The project vision is to enable the next generation of vertical lift vehicles with aggressive goals for efficiency, noise, and emissions, to expand current capabilities and develop new commercial markets. The RVLT Project invests in technologies that support conventional, non-conventional, and emerging vertical-lift aircraft in the very light to heavy vehicle classes. Research areas include acoustic, aeromechanics, drive systems, engines, icing, hybrid-electric systems, impact dynamics, experimental techniques, computational methods, and conceptual design. The project research is executed at NASA Ames, Glenn, and Langley Research Centers; the research extensively leverages partnerships with the US Army, the Federal Aviation Administration, industry, and academia. The primary facilities used by the project for testing of vertical-lift technologies include the 14- by 22-Ft Wind Tunnel, Icing Research Tunnel, National Full-Scale Aerodynamics Complex, 7- by 10-Ft Wind Tunnel, Rotor Test Cell, Landing and Impact Research facility, Compressor Test Facility, Drive System Test Facilities, Transonic Turbine Blade Cascade Facility, Vertical Motion Simulator, Mobile Acoustic Facility, Exterior Effects Synthesis and Simulation Lab, and the NASA Advanced Supercomputing Complex. To learn more about the RVLT Project, please stop by booth #1004 or visit their website at https://www.nasa.gov/aeroresearch/programs/aavp/rvlt.

  12. Global land-water nexus: Agricultural land and freshwater use embodied in worldwide supply chains.

    PubMed

    Chen, B; Han, M Y; Peng, K; Zhou, S L; Shao, L; Wu, X F; Wei, W D; Liu, S Y; Li, Z; Li, J S; Chen, G Q

    2018-02-01

    As agricultural land and freshwater inextricably interrelate and interact with each other, the conventional water and land policy in "silos" should give way to nexus thinking when formulating the land and water management strategies. This study constructs a systems multi-regional input-output (MRIO) model to expound global land-water nexus by simultaneously tracking agricultural land and freshwater use flows along the global supply chains. Furthermore, land productivity and irrigation water requirements of 160 crops in different regions are investigated to reflect the land-water linkage. Results show that developed economies (e.g., USA and Japan) and major large developing economies (e.g., mainland China and India) are the overriding drivers of agricultural land and freshwater use globally. In general, significant net transfers of these two resources are identified from resource-rich and less-developed economies to resource-poor and more-developed economies. For some crops, blue water productivity is inversely related to land productivity, indicating that irrigation water consumption is sometimes at odds with land use. The results could stimulus international cooperation for sustainable land and freshwater management targeting on original suppliers and final consumers along the global supply chains. Moreover, crop-specific land-water linkage could provide insights for trade-off decisions on minimizing the environmental impacts on local land and water resources. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Public Risk Assessment of Off-Nominal Genesis Entries

    NASA Technical Reports Server (NTRS)

    Mendeck, Gavin F.; Kadwa, Binaifer

    2006-01-01

    Public risk estimations were among the preparations for the entry of the Genesis sample return capsule. Personnel at the Johnson Space Center were requested to provide estimates of the public risk of off-nominal entries. These scenarios dealt with an incomplete trajectory maneuver that would result in the capsule landing outside of the controlled Utah Test and Training Range. Using a conservative approach to the inputs and assumptions, such off-nominal entries were demonstrated to fall within the project risk limits.

  14. Vertical profile of aerosols in the Himalayan region using an ultralight aircraft platform

    NASA Astrophysics Data System (ADS)

    Singh, A.; Mahata, K.; Rupakheti, M.; Lawrence, M. G.; Junkermann, W.

    2017-12-01

    Indo-gangetic plain (IGP) and Himalayan foothills have large spatial and temporal heterogeneity in aerosols characteristics. Regional meteorology around 850-500 mb plays an important role in the transformation and transportation of aerosols from west Asia to IGP, into Himalayan foothill, as well to high-altitude region of the Himalayas. In order to quantify the vertical and horizontal variation of aerosol properties in the Himalayan , an airborne campaign was carried out in the Pokhara Valley/Nepal (83°50'-84°10' E, 25°7'-28°15' N, 815 masl ) in two phases: test flights during May 2016 and an intensive airborne sampling flight in December-January 2017. This paper provides an overview of airborne measurement campaign from the first phase of measurements in May 2016. A two-seater microlight aircraft (IKARUS C 42) was used as the aerial platform. This was deemed the feasible option in Nepal for an aerial campaign; technical specification of the aircraft include an approximately 6 hrs of flying time, short-take off run, > 100 kgs of payload, suitable for spiral upward and downward profiling. The instrument package consist of GRIMM 1.108 for particle size distribution from 0.3 to 20 um at 6 seconds time resolution, and TSI CPC 3375 for total ultrafine particle (UFP) concentration at 1 s. The package also includes a Magee Scientific Aethalometer (AE42) for aerosol absorption at seven different wavelengths. Meteorological parameters include temperature and dew point at a sampling rate of 1 Hz or higher. The paper provides a snapshot of observed vertical profile (from 800 to 4500masl) of aerosols size, number and black carbon over one of populated mountain valley in Nepal during the pre-monsoon season. During the airborne measurement, local fires- mostly agriculture burn were observed, however no large scale forest fire was captured. Sharp morning and afternoon gradients were observed in the vertical profile for aerosol number and size, mostly dominated by <400 nm. The

  15. Preliminary study of a possible automatic landing system

    NASA Technical Reports Server (NTRS)

    Sherman, W. L.; Winfrey, S. W.

    1974-01-01

    Navigation and control laws for a possible automatic landing system have been investigated. The system makes use of data from an inertial table and either an airborne or ground radar to generate signals that guide the airplane to a landing. All landing maneuvers take place within a zone that extends 6000 m out from the touchdown point, 4000 m on each side of the runway center line, and 540 m high. The results show that the system can adequately control the airplane on steep, curved decelerating approaches to a landing that takes place with small errors from the desired landing point and desired airplane attitude. The system studied would interface well with the scanning beam microwave landing system (MLS). The use of this system with the MLS makes it possible to incorporate an independent landing monitor.

  16. Biomechanics research in ski jumping, 1991-2006.

    PubMed

    Schwameder, Hermann

    2008-01-01

    In this paper, I review biomechanics research in ski jumping with a specific focus on publications presented between 1991 and 2006 on performance enhancement, limiting factors of the take-off, specific training and conditioning, aerodynamics, and safety. The first section presents a brief description of ski jumping phases (in-run, take-off, early flight, stable flight, and landing) regarding the biomechanical and functional fundamentals. The most important and frequently used biomechanical methods in ski jumping (kinematics, ground reaction force analyses, muscle activation patterns, aerodynamics) are summarized in the second section. The third section focuses on ski jumping articles and research findings published after the establishment of the V-technique in 1991, as the introduction of this technique has had a major influence on performance enhancement, ski jumping regulations, and the construction of hill profiles. The final section proposes topics for future research in the biomechanics of ski jumping, including: take-off and early flight and the relative roles of vertical velocity and forward somersaulting angular momentum; optimal jumping patterns utilizing the capabilities of individual athletes; development of kinematic and kinetic feedback systems for hill jumps; comparisons of simulated and hill jumps; effect of equipment modifications on performance and safety enhancement.

  17. 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.

  18. 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

  19. Differences in production, carbon stocks and biodiversity outcomes of land tenure regimes in the Argentine Dry Chaco

    NASA Astrophysics Data System (ADS)

    Marinaro, Sofía; Grau, H. Ricardo; Gasparri, Néstor Ignacio; Kuemmerle, Tobias; Baumann, Matthias

    2017-04-01

    Rising global demand for agricultural products results in agricultural expansion and intensification, with substantial environmental trade-offs. The South American Dry Chaco contains some of the fastest expanding agricultural frontiers worldwide, and includes diverse forms of land management, mainly associated with different land tenure regimes; which in turn are segregated along environmental gradients (mostly rainfall). Yet, how these regimes impact the environment and how trade-offs between production and environmental outcomes varies remains poorly understood. Here, we assessed how biodiversity, biomass stocks, and agricultural production, measured in meat-equivalents, differ among land tenure regimes in the Dry Chaco. We calculated a land-use outcome index (LUO) that combines indices comparing actual vs. potential values of ‘preservation of biodiversity’ (PI), ‘standing biomass’ (BI) and ‘meat production’ (MI). We found land-use outcomes to vary substantially among land-tenure regimes. Protected areas showed a biodiversity index of 0.75, similar to that of large and medium-sized farms (0.72 in both farming systems), and higher than in the other tenure regimes. Biomass index was similar among land tenure regimes, whereas we found the highest median meat production index on indigenous lands (MI = 0.35). Land-use outcomes, however, varied more across different environmental conditions than across land tenure regimes. Our results suggest that in the Argentine Dry Chaco, there is no single land tenure regime that better minimizes the trade-offs between production and environmental outcomes. A useful approach to manage these trade-offs would be to develop geographically explicit guidelines for land-use zoning, identifying the land tenure regimes more appropriate for each zone.

  20. Improved transfer of graphene for gated Schottky-junction, vertical, organic, field-effect transistors.

    PubMed

    Lemaitre, Maxime G; Donoghue, Evan P; McCarthy, Mitchell A; Liu, Bo; Tongay, Sefaattin; Gila, Brent; Kumar, Purushottam; Singh, Rajiv K; Appleton, Bill R; Rinzler, Andrew G

    2012-10-23

    An improved process for graphene transfer was used to demonstrate high performance graphene enabled vertical organic field effect transistors (G-VFETs). The process reduces disorder and eliminates the polymeric residue that typically plagues transferred films. The method also allows for purposely creating pores in the graphene of a controlled areal density. Transconductance observed in G-VFETs fabricated with a continuous (pore-free) graphene source electrode is attributed to modulation of the contact barrier height between the graphene and organic semiconductor due to a gate field induced Fermi level shift in the low density of electronic-states graphene electrode. Pores introduced in the graphene source electrode are shown to boost the G-VFET performance, which scales with the areal pore density taking advantage of both barrier height lowering and tunnel barrier thinning. Devices with areal pore densities of 20% exhibit on/off ratios and output current densities exceeding 10(6) and 200 mA/cm(2), respectively, at drain voltages below 5 V.

  1. Radiocesium wash-off associated with soil erosion from various land uses after the Fukushima Dai-ichi NPP accident

    NASA Astrophysics Data System (ADS)

    Wakiyama, Yoshifumi; Onda, Yuichi; Yoshimura, Kazuya; Kato, Hiroaki; Konoplev, Alexei; Zheleznyak, Mark

    2014-05-01

    Soil erosion is the initial process which drives radiocesium into the aquatic systems and therefore the quantification of radiocesium wash-off associated with soil erosion is indispensable for mitigating the risks. This study presents two year's observation of soil erosion and radiocesium wash-off to quantify differences in radiocesium behavior in various land uses. Seven runoff plots were established in four landscapes; uncultivated farmland (Farmland A1, Farmland B1), cultivated farmland (Farmland A2, Farmland B2), grassland (Grassland A, Grassland B) and Japanese cedar forest (Forest) in Kawamata town, an area affected by the Fukushima Dai-ichi Nuclear Power Plant accident. The discharged sediments were collected approximately every two weeks. In laboratories, collected sediments were dried and weighed for calculating soil erosion rates (kg m-2) and served for measurements of radiocesium concentration (Bq kg-1) with HPGe detectors. The erosivity factor of the Universal Soil Loss Equation (R-factor: MJ mm ha-1 hr-1 yr-1) was calculated based on the data of precipitation. Standardized soil erosion rates (kg m-2 MJ-1 mm-1 ha hr yr), observed soil erosion rates divided by R-factor, was 1.8 × 10-4 in Farmland A1, 6.0 × 10-4 in Farmland A2, 1.5 × 10-3 in Farmland B1, 8.3 × 10-4 in Farmland B2, 9.6 × 10-6 in Grassland A, 5.9 × 10-6 in Grassland B and 2.3 × 10-6 in Forest. These erosion rates were basically proportional to their vegetation cover of soil surfaces except for cultivated farmlands. Concentrations of Cs-137 in eroded sediments basically depended on the local deposition of Cs-137 and varied enormously with ranging several orders of magnitude in all the landscapes. For the observation period of time decreasing trends in concentrations of Cs-137 in eroded sediments were not obvious. To compare these results with those of Chernobyl, we calculated normalized 'solid' wash-off coefficient (m2 g-1) with dividing the mean total concentration of Cs-137 in

  2. Carbon lost and carbon gained: a study of vegetation and carbon trade-offs among diverse land uses in Phoenix, Arizona.

    PubMed

    McHale, Melissa R; Hall, Sharon J; Majumdar, Anandamayee; Grimm, Nancy B

    2017-03-01

    Human modification and management of urban landscapes drastically alters vegetation and soils, thereby altering carbon (C) storage and rates of net primary productivity (NPP). Complex social and ecological processes drive vegetation cover in cities, leading to heterogeneity in C dynamics depending on regional climate, land use, and land cover. Recent work has demonstrated homogenization in ecological processes within human-dominated landscapes (the urban convergence hypothesis) in soils and biotic communities. However, a lack of information on vegetation in arid land cities has hindered an understanding of potential C storage and NPP convergence across a diversity of ecosystem types. We estimated C storage and NPP of trees and shrubs for six different land-use types in the arid metropolis of Phoenix, Arizona, USA, and compared those results to native desert ecosystems, as well as other urban and natural systems around the world. Results from Phoenix do not support the convergence hypothesis. In particular, C storage in urban trees and shrubs was 42% of that found in desert vegetation, while NPP was only 20% of the total NPP estimated for comparable natural ecosystems. Furthermore, the overall estimates of C storage and NPP associated with urban trees in the CAP ecosystem were much lower (8-63%) than the other cities included in this analysis. We also found that C storage (175.25-388.94 g/m 2 ) and NPP (8.07-15.99 g·m -2 ·yr -1 ) were dominated by trees in the urban residential land uses, while in the desert, shrubs were the primary source for pools (183.65 g/m 2 ) and fluxes (6.51 g·m -2 ·yr -1 ). These results indicate a trade-off between shrubs and trees in arid ecosystems, with shrubs playing a major role in overall C storage and NPP in deserts and trees serving as the dominant C pool in cities. Our research supports current literature that calls for the development of spatially explicit and standardized methods for analyzing C dynamics associated with

  3. Optimal landing of a helicopter in autorotation

    NASA Technical Reports Server (NTRS)

    Lee, A. Y. N.

    1985-01-01

    Gliding descent in autorotation is a maneuver used by helicopter pilots in case of engine failure. The landing of a helicopter in autorotation is formulated as a nonlinear optimal control problem. The OH-58A helicopter was used. Helicopter vertical and horizontal velocities, vertical and horizontal displacement, and the rotor angle speed were modeled. An empirical approximation for the induced veloctiy in the vortex-ring state were provided. The cost function of the optimal control problem is a weighted sum of the squared horizontal and vertical components of the helicopter velocity at touchdown. Optimal trajectories are calculated for entry conditions well within the horizontal-vertical restriction curve, with the helicopter initially in hover or forwared flight. The resultant two-point boundary value problem with path equality constraints was successfully solved using the Sequential Gradient Restoration Technique.

  4. Landing Energy Dissipation for Manned Reentry Vehicles

    NASA Technical Reports Server (NTRS)

    Fisher, Lloyd J., Jr.

    1960-01-01

    Analytical and experimental investigations have been made to determine the landing-energy-dissipation characteristics for several types of landing gear for manned reentry vehicles. The landing vehicles are considered in two categories: those having essentially vertical-descent paths, the parachute-supported vehicles, and those having essentially horizontal paths, the lifting vehicles. The energy-dissipation devices discussed are crushable materials such as foamed plastics and honeycomb for internal application in couch-support systems, yielding metal elements as part of the structure of capsules or as alternates for oleos in landing-gear struts, inflatable bags, braking rockets, and shaped surfaces for water impact. It appears feasible to readily evaluate landing-gear systems for internal or external application in hard-surface or water landings by using computational procedures and free-body landing techniques with dynamic models. The systems investigated have shown very interesting energy-dissipation characteristics over a considerable range of landing parameters. Acceptable gear can be developed along lines similar to those presented if stroke requirements and human-tolerance limits are considered.

  5. [Effects of land use structure change on regional ecological health--taking Shapingba County as an example].

    PubMed

    Wang, Cheng; Wei, Chaofu; Gao, Ming; Luo, Guanglian; Jiang, Wei

    2005-12-01

    Land resource is the carrier for the exchange of matter, energy and information flows, while the change velocity and the intensity of land use has strong effects on the ecological processes such as matter circulation, energy flow, and biologic diversity. Land use structure change will alter the type, area, and spatial distribution of ecosystem, and in the meantime, result in the changes of regional ecological health. Employing the principles and methods of landscape ecology, and through endowing relative ecological value to land use type, this paper analyzed the charaeteristics of recent 10 years land use change in Shapingba County of Chongqing, and discussed the effects of land use change on regional ecological health, aimed to provide scientific references for land use planning and sustainable land resource utilization. The results indicated that transformation often occurred among different land use types, and the land use structure in each transformation phase differed quite obviously. Under different land use structure, there was a great disparity in relative ecological value of sub-ecosystems, which played various roles in regional ecological health. In general, the regional relative ecological value embodied both increase and decrease. In the future, the relative ecological value of sub-ecosystem would represent three tendencies, i.e., increase first and decrease then, continuous decrease, and continuous increase. The situation of regional ecological health would gradually become better.

  6. Balancing Power Absorption and Structural Loading for a Novel Fixed-Bottom Wave Energy Converter with Nonideal Power Take-Off in Regular Waves: Preprint

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

    Tom, Nathan M; Yu, Yi-Hsiang; Wright, Alan D

    In this work, the net power delivered to the grid from a nonideal power take-off (PTO) is introduced followed by a review of the pseudo-spectral control theory. A power-to-load ratio, used to evaluate the pseudo-spectral controller performance, is discussed, and the results obtained from optimizing a multiterm objective function are compared against results obtained from maximizing the net output power to the grid. Simulation results are then presented for four different oscillating wave energy converter geometries to highlight the potential of combing both geometry and PTO control to maximize power while minimizing loads.

  7. Modifying landing mat material properties may decrease peak contact forces but increase forefoot forces in gymnastics landings.

    PubMed

    Mills, Chris; Yeadon, Maurice R; Pain, Matthew T G

    2010-09-01

    This study investigated how changes in the material properties of a landing mat could minimise ground reaction forces (GRF) and internal loading on a gymnast during landing. A multi-layer model of a gymnastics competition landing mat and a subject-specific seven-link wobbling mass model of a gymnast were developed to address this aim. Landing mat properties (stiffness and damping) were optimised using a Simplex algorithm to minimise GRF and internal loading. The optimisation of the landing mat parameters was characterised by minimal changes to the mat's stiffness (<0.5%) but increased damping (272%) compared to the competition landing mat. Changes to the landing mat resulted in reduced peak vertical and horizontal GRF and reduced bone bending moments in the shank and thigh compared to a matching simulation. Peak bone bending moments within the thigh and shank were reduced by 6% from 321.5 Nm to 302.5Nm and GRF by 12% from 8626 N to 7552 N when compared to a matching simulation. The reduction in these forces may help to reduce the risk of bone fracture injury associated with a single landing and reduce the risk of a chronic injury such as a stress fracture.

  8. Urban land use of the Sao Paulo metropolitan area by automatic analysis of LANDSAT data

    NASA Technical Reports Server (NTRS)

    Parada, N. D. J. (Principal Investigator); Niero, M.; Foresti, C.

    1983-01-01

    The separability of urban land use classes in the metropolitan area of Sao Paulo was studied by means of automatic analysis of MSS/LANDSAT digital data. The data were analyzed using the media K and MAXVER classification algorithms. The land use classes obtained were: CBD/vertical growth area, residential area, mixed area, industrial area, embankment area type 1, embankment area type 2, dense vegetation area and sparse vegetation area. The spectral analysis of representative samples of urban land use classes was done using the "Single Cell" analysis option. The classes CBD/vertical growth area, residential area and embankment area type 2 showed better spectral separability when compared to the other classes.

  9. Ankle taping does not impair performance in jump or balance tests.

    PubMed

    Abián-Vicén, Javier; Alegre, Luis M; Fernández-Rodríguez, J Manuel; Lara, Amador J; Meana, Marta; Aguado, Xavier

    2008-01-01

    This study aimed to investigate the influence of prophylactic ankle taping on two balance tests (static and dynamic balance) and one jump test, in the push off and the landing phase. Fifteen active young subjects (age: 21.0 ± 4.4 years) without previous ankle injuries volunteered for the study. Each participant performed three tests in two different situations: with taping and without taping. The tests were a counter movement jump, static balance, and a dynamic posturography test. The tests and conditions were randomly performed. The path of the center of pressures was measured in the balance tests, and the vertical ground reaction forces were recorded during the push-off and landing phases of the counter movement jump. Ankle taping had no influence on balance performance or in the push off phase of the jump. However, the second peak vertical force value during the landing phase of the jump was 12% greater with ankle taping (0.66 BW, 95% CI -0.64 to 1.96). The use of prophylactic ankle taping had no influence on the balance or jump performance of healthy young subjects. In contrast, the taped ankle increased the second peak vertical force value, which could be related to a greater risk of injury produced by the accumulation of repeated impacts in sports where jumps are frequently performed. Key pointsAnkle taping has no influence on balance performance.Ankle taping does not impair performance during the push-off phase of the jump.Ankle taping could increase the risk of injury during landings by increasing peak forces.

  10. Ankle Taping Does Not Impair Performance in Jump or Balance Tests

    PubMed Central

    Abián-Vicén, Javier; Alegre, Luis M.; Fernández-Rodríguez, J. Manuel; Lara, Amador J.; Meana, Marta; Aguado, Xavier

    2008-01-01

    This study aimed to investigate the influence of prophylactic ankle taping on two balance tests (static and dynamic balance) and one jump test, in the push off and the landing phase. Fifteen active young subjects (age: 21.0 ± 4.4 years) without previous ankle injuries volunteered for the study. Each participant performed three tests in two different situations: with taping and without taping. The tests were a counter movement jump, static balance, and a dynamic posturography test. The tests and conditions were randomly performed. The path of the center of pressures was measured in the balance tests, and the vertical ground reaction forces were recorded during the push-off and landing phases of the counter movement jump. Ankle taping had no influence on balance performance or in the push off phase of the jump. However, the second peak vertical force value during the landing phase of the jump was 12% greater with ankle taping (0.66 BW, 95% CI -0.64 to 1.96). The use of prophylactic ankle taping had no influence on the balance or jump performance of healthy young subjects. In contrast, the taped ankle increased the second peak vertical force value, which could be related to a greater risk of injury produced by the accumulation of repeated impacts in sports where jumps are frequently performed. Key pointsAnkle taping has no influence on balance performance.Ankle taping does not impair performance during the push-off phase of the jump.Ankle taping could increase the risk of injury during landings by increasing peak forces. PMID:24149902

  11. Land Use and Change

    NASA Technical Reports Server (NTRS)

    Irwin, Daniel E.

    2004-01-01

    The overall purpose of this training session is to familiarize Central American project cooperators with the remote sensing and image processing research that is being conducted by the NASA research team and to acquaint them with the data products being produced in the areas of Land Cover and Land Use Change and carbon modeling under the NASA SERVIR project. The training session, therefore, will be both informative and practical in nature. Specifically, the course will focus on the physics of remote sensing, various satellite and airborne sensors (Landsat, MODIS, IKONOS, Star-3i), processing techniques, and commercial off the shelf image processing software.

  12. On angled bounce-off impact of a drop impinging on a flowing soap film

    NASA Astrophysics Data System (ADS)

    Basu, Saikat; Yawar, Ali; Concha, Andres; Bandi, M. M.

    2017-12-01

    Small drops impinging obliquely on thin flowing soap films frequently demonstrate the rare emergence of bulk elastic effects working in-tandem with the more commonplace hydrodynamic interactions. Three collision regimes are observable: (a) drop piercing through the film, (b) it coalescing with the flow, and (c) it bouncing off the film surface. During impact, the drop deforms along with a bulk elastic deformation of the film. For impacts that are close-to-tangential, the bounce-off regime predominates. We outline a reduced order analytical framework assuming a deformable drop and a deformable three-dimensional film, and the idealization invokes a phase-based parametric study. Angular inclination of the film and the ratio of post and pre-impact drop sizes entail the phase parameters. We also perform experiments with vertically descending droplets (constituted from deionized water) impacting against an inclined soap film, flowing under constant pressure head. Model-predicted phase domain for bounce-off compares well to our experimental findings. Additionally, the experiments exhibit momentum transfer to the film in the form of shed vortex dipoles, along with propagation of free surface waves. On consulting prior published work, we note that for locomotion of water-walking insects using an impulsive action, the momentum distribution to the shed vortices and waves are both significant, taking up respectively 2/3 and 1/3 of the imparted streamwise momentum. Considering the visually similar impulse actions, this theory, despite its assumption of a quiescent liquid bath of infinite depth, is applied to the drop bounce-off experiments, and the resultant shed vortex dipole momenta are compared to the momenta of the coherent vortex structures computed from particle imaging velocimetry data. The magnitudes reveal identical order (10-7 N s), suggesting that notwithstanding the disparities, the bounce-off regime may be tapped as a toy analog for impulse-based interfacial

  13. Mapping environmental land use conflict potentials and ecosystem services in agricultural watersheds.

    PubMed

    Kim, Ilkwon; Arnhold, Sebastian

    2018-07-15

    In mountainous watersheds, agricultural land use cause changes in ecosystem services, with trade-offs between crop production and erosion regulation. Management of these watersheds can generate environmental land use conflicts among regional stakeholders with different interests. Although several researches have made a start in mapping land use conflicts between human activities and conservation, spatial assessment of land use conflicts on environmental issues and ecosystem service trade-offs within agricultural areas has not been fully considered. In this study, we went further to map land use conflicts between agricultural preferences for crop production and environmental emphasis on erosion regulation. We applied an agricultural land suitability index, based on multi-criteria analysis, to estimate the spatial preference of agricultural activities, while applying the Revised Universal Soil Loss Equation (RUSLE) to reflect the environmental importance of soil erosion. Then, we classified the agricultural catchment into four levels of land use conflicts (lowest, low, high and highest) according to preference and importance of farmland areas, and we compared the classes by crop type. Soil loss in agricultural areas was estimated as 45.1thayr, and agricultural suitability as 0.873; this indicated that land use conflicts in the catchment could arise between severe soil erosion (environmental importance) and agricultural suitability (land preferences). Dry-field farms are mainly located in areas of low land use conflict level, where land preference outweighs environmental importance. When we applied farmland management scenarios with consideration of services, conversion to highest-conflict areas (Scenario 1) as 7.5% of the total area could reduce soil loss by 24.6%, while fallow land management (Scenario 2) could decrease soil loss 19.4% more than the current scenario (Business as usual). The result could maximize land management plans by extracting issues of spatial

  14. High-performance vertical organic transistors.

    PubMed

    Kleemann, Hans; Günther, Alrun A; Leo, Karl; Lüssem, Björn

    2013-11-11

    Vertical organic thin-film transistors (VOTFTs) are promising devices to overcome the transconductance and cut-off frequency restrictions of horizontal organic thin-film transistors. The basic physical mechanisms of VOTFT operation, however, are not well understood and VOTFTs often require complex patterning techniques using self-assembly processes which impedes a future large-area production. In this contribution, high-performance vertical organic transistors comprising pentacene for p-type operation and C60 for n-type operation are presented. The static current-voltage behavior as well as the fundamental scaling laws of such transistors are studied, disclosing a remarkable transistor operation with a behavior limited by injection of charge carriers. The transistors are manufactured by photolithography, in contrast to other VOTFT concepts using self-assembled source electrodes. Fluorinated photoresist and solvent compounds allow for photolithographical patterning directly and strongly onto the organic materials, simplifying the fabrication protocol and making VOTFTs a prospective candidate for future high-performance applications of organic transistors. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Power-to-load balancing for asymmetric heave wave energy converters with nonideal power take-off

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

    Tom, Nathan M.; Madhi, Farshad; Yeung, Ronald W.

    The aim of this study is to maximize the power-to-load ratio for asymmetric heave wave energy converters. Linear hydrodynamic theory was used to calculate bounds of the expected time-averaged power (TAP) and corresponding surge-restraining force, pitch-restraining torque, and power take-off (PTO) control force with the assumption of sinusoidal displacement. This paper formulates an optimal control problem to handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads in regular and irregular waves. Penalty weights are placed on the surge-restraining force, pitch-restraining torque, and PTO actuation force, thereby allowing the controlmore » focus to concentrate on either power absorption or load mitigation. The penalty weights are used to control peak structural and actuator loads that were found to curb the additional losses in power absorption associated with a nonideal PTO. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results for 'The Berkeley Wedge' in the form of output TAP, reactive TAP needed to drive WEC motion, and the amplitudes of the surge-restraining force, pitch-restraining torque, and PTO control force are shown.« less

  16. Power-to-load balancing for asymmetric heave wave energy converters with nonideal power take-off

    DOE PAGES

    Tom, Nathan M.; Madhi, Farshad; Yeung, Ronald W.

    2017-12-11

    The aim of this study is to maximize the power-to-load ratio for asymmetric heave wave energy converters. Linear hydrodynamic theory was used to calculate bounds of the expected time-averaged power (TAP) and corresponding surge-restraining force, pitch-restraining torque, and power take-off (PTO) control force with the assumption of sinusoidal displacement. This paper formulates an optimal control problem to handle an objective function with competing terms in an attempt to maximize power capture while minimizing structural and actuator loads in regular and irregular waves. Penalty weights are placed on the surge-restraining force, pitch-restraining torque, and PTO actuation force, thereby allowing the controlmore » focus to concentrate on either power absorption or load mitigation. The penalty weights are used to control peak structural and actuator loads that were found to curb the additional losses in power absorption associated with a nonideal PTO. Thus, in achieving these goals, a per-unit gain in TAP would not lead to a greater per-unit demand in structural strength, hence yielding a favorable benefit-to-cost ratio. Demonstrative results for 'The Berkeley Wedge' in the form of output TAP, reactive TAP needed to drive WEC motion, and the amplitudes of the surge-restraining force, pitch-restraining torque, and PTO control force are shown.« less

  17. Cities as selective land predators? A lesson on urban growth, deregulated planning and sprawl containment.

    PubMed

    Colantoni, Andrea; Grigoriadis, Efstathios; Sateriano, Adele; Venanzoni, Giuseppe; Salvati, Luca

    2016-03-01

    The present study investigates changes in the use of land caused by the expansion of an informal city in the Mediterranean region (Athens, Greece) and it proposes a simplified methodology to assess selective land take at the scale of municipalities. The amount of land take over twenty years (1987-2007) for cropland, sparsely vegetated areas and natural land was compared with the surface area of the respective class at the beginning of the study period (1987). Indicators of selective land take by class were correlated with socioeconomic indicators at the scale of municipalities to verify the influence of the local context and the impact of urban planning on land take processes. Evidence indicates that urban expansion into fringe land consumes primarily cropland and sparse vegetation in the case of the Athens' metropolitan region. Cropland and sparse vegetation were consumed proportionally more than the respective availability in 16 municipalities out of 60. Agricultural land take was positively correlated with population density and growth rate, rate of participation to the job market and road density. Sparse vegetation land take was observed in municipalities with predominance of high density settlements. As a result of second-home expansion in coastal municipalities, natural land was converted to urban use in proportion to the availability in the landscape. Urban planning seems to have a limited impact on selective land take. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. The effects of altered distances between obstacles on the jump kinematics and apparent joint angulations of large agility dogs.

    PubMed

    Birch, E; Boyd, J; Doyle, G; Pullen, A

    2015-05-01

    Canine agility is a rapidly growing sport in the UK. However, there is a paucity of scientific research examining jump kinematics and associated health and welfare implications of the discipline. The aim of this research was to examine differences in jump kinematics and apparent joint angulation of large (>431 mm at the withers) agility dogs (n = 54), when the distance between hurdles was altered (3.6 m, 4 m and 5 m apart) and to determine how level of skill impacted upon jump kinematics. Significant differences were observed for both the take-off (P <0.001) and landing distances (P <0.001) between the 3.6 m, 4 m and 5 m distances. Further differences were observed when level of skill was controlled for; take-off (F[3,55] = 5.686, P = 0.002) and landing (F[3,55] = 7.552, P <0.001) distances differed at the 3.6 m distance, as did the take-off distance at the 4 m hurdle distance (F[3,50] = 6.168, P = 0.001). Take-off and landing speeds differed for hurdle distances (P <0.001) and level of skill (P <0.001). There were significant differences in apparent neck angle during take-off and landing (P <0.001), lumbar spine angles during take-off, bascule and landing (P <0.01), and in shoulder angles during the bascule phase (P <0.05). The results indicate that agility dogs alter their jumping patterns to accommodate the spacing between hurdles, which ultimately may impact long term health and welfare due to altered kinematics. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Highly flexible electronics from scalable vertical thin film transistors.

    PubMed

    Liu, Yuan; Zhou, Hailong; Cheng, Rui; Yu, Woojong; Huang, Yu; Duan, Xiangfeng

    2014-03-12

    Flexible thin-film transistors (TFTs) are of central importance for diverse electronic and particularly macroelectronic applications. The current TFTs using organic or inorganic thin film semiconductors are usually limited by either poor electrical performance or insufficient mechanical flexibility. Here, we report a new design of highly flexible vertical TFTs (VTFTs) with superior electrical performance and mechanical robustness. By using the graphene as a work-function tunable contact for amorphous indium gallium zinc oxide (IGZO) thin film, the vertical current flow across the graphene-IGZO junction can be effectively modulated by an external gate potential to enable VTFTs with a highest on-off ratio exceeding 10(5). The unique vertical transistor architecture can readily enable ultrashort channel devices with very high delivering current and exceptional mechanical flexibility. With large area graphene and IGZO thin film available, our strategy is intrinsically scalable for large scale integration of VTFT arrays and logic circuits, opening up a new pathway to highly flexible macroelectronics.

  20. Unanticipated ankle inversions are significantly different from anticipated ankle inversions during drop landings: overcoming anticipation bias.

    PubMed

    Dicus, Jeremy R; Seegmiller, Jeff G

    2012-05-01

    Few ankle inversion studies have taken anticipation bias into account or collected data with an experimental design that mimics actual injury mechanisms. Twenty-three participants performed randomized single-leg vertical drop landings from 20 cm. Subjects were blinded to the landing surface (a flat force plate or 30° inversion wedge on the force plate). After each trial, participants reported whether they anticipated the landing surface. Participant responses were validated with EMG data. The protocol was repeated until four anticipated and four unanticipated landings onto the inversion wedge were recorded. Results revealed a significant main effect for landing condition. Normalized vertical ground reaction force (% body weights), maximum ankle inversion (degrees), inversion velocity (degrees/second), and time from contact to peak muscle activation (seconds) were significantly greater in unanticipated landings, and the time from peak muscle activation to maximum VGRF (second) was shorter. Unanticipated landings presented different muscle activation patterns than landings onto anticipated surfaces, which calls into question the usefulness of clinical studies that have not controlled for anticipation bias.