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Sample records for active basement-involved thrust

  1. Seismic Activity along the Main Boundary Thrust (MBT), Pakistan

    Main Boundary Thrust (MBT) is the main frontal thrust of the Himalayan range, which runs about 1500 km from Assam in the east to Kashmir in the west. The MBT fault zone represents very high earthquake potential in this region, as it is the source of many earthquakes, which are amongst the greatest ever-recorded events. These include 1905 Kangra earthquake of M 8.6 1934 Bihar-Nepal earthquake of M 8.4 and the great Assam earthquakes of 1897 and 1950. The rupture, which caused these earthquakes, is occurred in the detachment in the vicinity of the surface trace of MBT. Keeping the above fact in view. A seismicity map of the area within the 100 km of the MBT have been prepared using the seismological data from various sources for the period of 1904-2004. on the basis of the spatial distribution of the epicenters, the MBT is considered to be active. Focal mechanism studies (FMS) of three events for the period of 1989-1993 within the MBT forming the western portion of Hazara Kashmir Syntaxis (near Islamabad) have been carried out. Two of them are left lateral strike slip, whereas one is thrust with minor left lateral strike slip component. Dominance of strike slip over thrusting/reverse has been observed with the clear indication of the left lateral splays activation of MBT. However more data is required to confirm this interpretation. (author)

  2. TRANSIENT TEMPERATURE FIELD IN ACTIVE THRUST MAGNETIC BEARING

    Sun Shouqun; Geng Haipeng; Guo Keqian

    2005-01-01

    A transient temperature field model in a thrust magnetic bearing is built in which the heat resources come mainly from the eddy-current loss of solid cores and the copper loss of coils. The transient temperature field, system temperature rise and the thermo-equilibrium state during the rotor starting-up are calculated considering only the copper loss and the eddy-current loss. The numerical results indicate that the temperatures in coils and in magnets rise rapidly, their thermo-equilibrium states are formed within a short time. The temperatures in a thrust-disk and in a rotor rise slowly, their thermo-equilibrium states are formed after a long period time. The temperatures of the thrust-disk and the rotor are far higher than the temperatures of coils and/or magnets after the thermo-equilibrium state has come into being.

  3. Large-scale thrusting along the northern margin of the Tibetan Plateau and the southwest Tarim basin: 230 km long active Hotian thrust sheet

    Suppe, J.; Wang, X.; He, D.; Liang, H.

    2015-12-01

    We present the geometry, kinematics and mechanics of large-scale active thrusting in the western Kunlunshan and southwest Tarim basin, which accounts for ~130-165km total shortening of Tarim crust at the northern margin of Tibet. The great frontal structure is the ~230km long bedding-parallel Hotian thrust sheet, which is perhaps the longest active intact thrust sheet in the world, composed of flat-lying strata of the Tarim basin sliding northward on a regional gypsum detachment at the base of the Cenozoic sequence. The toe of the Hotian thrust ramps to the surface two thirds of the way across the Tarim basin, forming the Selibuya-Mazartag hills in the Taklamakan sand desert. At the southern edge of the Tarim basin in the Kunlunshan foothills, a set of high-amplitude anticlines are growing by complex break-forward ramping and wedging in the Hotian thrust sheet as it steps up to the Cenozoic gypsum detachment from a regional Cambrian evaporate detachment that extends under Tibet. More interior structures such as the Tiklik thrust bring older strata and Proterozoic basement to the surface, together with their Cenozoic Tarim cover in the Buya basin. The Cambrian detachment also extends northward under the Tarim basin with minor hanging-wall deformation that locally warps the overlying Hotian thrust sheet, producing a complete syntectonic record in seismically imaged growth strata of its northward motion over these warps. Seismic profiles in the southwest Tarim foothill belt also reveal widespread growth strata that record much of the structural history beginning in the early Pliocene Atushi Formation. Ages of seismic reflectors are calibrated to a surface magnetostratigraphic sequence (Zheng et al., 2000). The beginning of thrusting and folding in the southwest Tarim basin north of the Tiklik thrust is dated at 3.6Ma with shortening >25km and a progressive northward propagation toward the Selibuya-Mazartag hills. The overall shortening rate is ~10 mm/yr. The gypsum

  4. A new structural model of the Pachitea Basin, Peru: Interaction of thick-skinned tectonics and salt detached thrusting

    Witte, J.; Rebaza, J.; Westlund, D.; Stratton, M.; Alegria, C.

    2015-11-01

    We present four new structural transects, a new seismo-stratigraphic correlation, a refined structural model and new shortening rates for the Pachitea Basin (=PB), Peru. Our results are based on the integration and detailed interpretation of newly acquired industry seismic (2D, 2005 vintage), existing well data, existing and proprietary surface geology data and newly acquired aero magnetic data (2007 vintage). Our assessment confirms the presence of at least four distinct structural styles in the area, thick-skinned structures, thin-skinned detachment thrusting, salt-tectonics and localized strike-slip tectonics. Based on seismo-stratigraphic correlations we conclude that the oldest rocks carried to outcrop by the San Matias (=SM) thrust are of Jurassic age. We interpret the thin-skinned master detachment to be located in varying positions, directly below or above, autochtonous salt pillows. Timing assessment of the SM thrust sheet reveals that it has been active from at least ˜5 Ma to post-2 Ma, supporting regionally published timing data for this latitude. Positive topographic surface expressions indicate ongoing contraction along the mountain front of the Peruvian Eastern Cordillera (=EC). Across the PB we calculate between 2.6% and 5.5% for thick-skinned shortening and at least 25.5% for the thin-skinned shortening. For the SM thrust sheet we calculate a slip-rate of ˜1-1.6 mm/yr, which is in line with published slip rates on individual thrusts from around the world. Observations along the SM thrust system indicate that thin- and thick-skinned systems interact mechanically, and that they have been active intermittently. We conclude that the location of salt pillows as well as pre-existing or growing basement-involved structures helped trigger the SM thrust. Different types of salt bodies are present in the PB, autochtonous pillows, slightly thrusted pillows and allochtonous diapirs. Our results provide new insight into the structural interplay, particularly

  5. Design and implementation of an active rectangular aerostatic thrust bearing stage with electromagnetic actuators

    MAO JunHong; LI LiChuan

    2009-01-01

    The design and implementation of an active rectangular aerostaUc thrust bearing stage with electro-magnetic actuators are presented. The stage is fundamentally precise and simple since the out-of-plane degree-of-freedoms (DOF) of a thrust air bearing are closed-loop controlled by electromagnetic actua-tors. The design is one-moving-part with mechanical symmetry, and a commercially available air bear-ing is rigidly attached to the table. The actuators are four independent coils mounted to the guiding surface of the table with iron cores, which are directly machined on the table. A bench level prototype system is developed and out-of-plane axes decoupled models of the system are derived. A control al-gorithm synthesized by arbitrarily placing closed-loop poles according to the model with air bearing dynamics neglected is implemented by C programming language running on the DOS platform. The stage is capable of vertical direction precision micro-positioning and guiding 3-DOF plane motions without limiting the working range of plane motions. Positioning accuracy of the stage no longer de-pends upon design and manufacturing of an air bearing, while passive preload of the stage for a flat film aerostatic thrust bearing is eliminated.

  6. Connecting the Yakima fold and thrust belt to active faults in the Puget Lowland, Washington

    Blakely, Richard J.; Sherrod, Brian L.; Weaver, Craig S.; Wells, Ray E.; Rohay, Alan C.; Barnett, Elizabeth A.; Knepprath, Nichole E.

    2011-07-01

    High-resolution aeromagnetic surveys of the Cascade Range and Yakima fold and thrust belt (YFTB), Washington, provide insights on tectonic connections between forearc and back-arc regions of the Cascadia convergent margin. Magnetic surveys were measured at a nominal altitude of 250 m above terrain and along flight lines spaced 400 m apart. Upper crustal rocks in this region have diverse magnetic properties, ranging from highly magnetic rocks of the Miocene Columbia River Basalt Group to weakly magnetic sedimentary rocks of various ages. These distinctive magnetic properties permit mapping of important faults and folds from exposures to covered areas. Magnetic lineaments correspond with mapped Quaternary faults and with scarps identified in lidar (light detection and ranging) topographic data and aerial photography. A two-dimensional model of the northwest striking Umtanum Ridge fault zone, based on magnetic and gravity data and constrained by geologic mapping and three deep wells, suggests that thrust faults extend through the Tertiary section and into underlying pre-Tertiary basement. Excavation of two trenches across a prominent scarp at the base of Umtanum Ridge uncovered evidence for bending moment faulting possibly caused by a blind thrust. Using aeromagnetic, gravity, and paleoseismic evidence, we postulate possible tectonic connections between the YFTB in eastern Washington and active faults of the Puget Lowland. We suggest that faults and folds of Umtanum Ridge extend northwestward through the Cascade Range and merge with the Southern Whidbey Island and Seattle faults near Snoqualmie Pass 35 km east of Seattle. Recent earthquakes (MW ≤ 5.3) suggest that this confluence of faults may be seismically active today.

  7. Late Holocene activity and historical earthquakes of the Qiongxi thrust fault system in the southern Longmen Shan fold-and-thrust belt, eastern Tibetan Plateau

    Wang, Maomao; Jia, Dong; Lin, Aiming; Shen, Li; Rao, Gang; Li, Yiquan

    2013-01-01

    The 12 May 2008 Wenchuan earthquake (Mw 7.9) generated a 285-km-long surface rupture zone along the Longmen Shan fold-and-thrust belt (LSFTB) on the eastern margin of Tibetan Plateau. The Wenchuan earthquake did not rupture into the southwestern Longmen Shan, along which there is no evidence for large paleo- or historical earthquakes. Seismic reflection profiles and field investigations reveal that the 50-km-long Qiongxi thrust fault (QTF) of the southern LSFTB is currently active. The QTF consists of three west-dipping ramp segments overlain by fault-bend folds rooted in a regional detachment that transfers shortening from the mountain belt into the Sichuan basin. Trench investigations, coupled with interpretations of seismic reflection profiles and radiocarbon results, show that a recent surface-rupturing earthquake occurred on the QTF during the Late Ming to Qing Dynasty, between AD 1600 and 1800. In addition, seismic reflection profile and topographic analysis indicate the presence of a subtle topographic, produced by kink-band migration folding above a fault bend at about 5 km depth. These findings confirm that the QTF is a significant seismic hazard, and that it should be incorporated into current regional seismic hazard models for the densely populated Sichuan basin.

  8. Crustal scale geometry of the Zagros fold–thrust belt, Iran

    McQuarrie, Nadine

    2004-01-01

    Balanced cross-sections across the Zagros fold–thrust belt in Iran are used to analyze the geometry of deformation within the sedimentary cover rocks, and to test the hypothesis of basement involved thrusting throughout the fold–thrust belt. Although the Zagros deformation front is a relatively rectilinear feature, the sinuous map-view morphology of the mountain front is a result of a 6 km structural step in the regional elevation of the Asmari Limestone that produces a pronounced step in top...

  9. Active control of surge in centrifugal compressors using magnetic thrust bearing actuation

    Sanadgol, Dorsa

    This research presents a new method for active surge control in centrifugal compressors with unshrouded impellers using a magnetic thrust bearing to modulate the impeller tip clearance. Magnetic bearings offer the potential for active control of flow instabilities. This capability is highly dependent on the sensitivity of the compressor characteristics to blade tip clearance. If the position of the shaft can be actuated with sufficient authority and speed, the induced pressure modulation makes control of surge promising. The active nature of the magnetic bearing system makes the real-time static and dynamic positioning of the rotor and therefore modulation of the impeller tip clearance possible. A theoretical model is first established that describes the sensitivity of the centrifugal compressor characteristic curve to tip clearance variations induced by axial motion of the rotor. Results from simulation of the nonlinear model for a single stage high-speed centrifugal compressor show that using the proposed control method, mass flow and pressure oscillations associated with compressor surge are quickly suppressed with acceptable tip clearance excursions, typically less than 20% of the available clearance. It is shown that it is possible to produce adequate axial excursions in the clearance between the impeller blades and the adjacent stationary shroud using a magnetic thrust bearing with practical levels of drive voltage. This surge control method would allow centrifugal compressors to reliably and safely operate with a wider range than is currently done in the field. The principal advantage of the proposed approach over conventional surge control methods lies in that, in machines already equipped with magnetic bearing, the method can potentially be implemented by simply modifying controller software. This dispenses with the need to introduce additional hardware, permitting adaptation of existing machinery at virtually no cost. In addition, since the controller is

  10. Drainage response to active tectonics and evolution of tectonic geomorphology across the Himalayan Frontal Thrust, Kumaun Himalaya

    Luirei, Khayingshing; Bhakuni, Surendra S.; Kothyari, Girish Ch.

    2015-06-01

    We present the results of integrated studies of geomorphic indices of drainage networks and landforms developed across the mountain front along the Himalayan Frontal Thrust (HFT) between the Dabka and Baur rivers, Kumaun Himalaya. The HFT is a morphogenic structure in nature, creating a 100-m-high E-W trending escarpment that extends ~ 21 km. Geomorphological evidence indicates ~ 10.5 km westward migration of the Dabka River and ~ 5.2 km eastward migration of the Baur River. These migrations are a result of uplift of the hanging wall along the HFT. The HFT is offset by a transverse fault, which suggests that the latter postdates the reactivation of the HFT between 500 and 100 ka. Presence of different levels of strath terraces along the mountain front suggests the active nature of the HFT. To assess the relative tectonic activity, morphometric indices such as stream-gradient (SL) index, mountain front sinuosity (Smf) index, and ratio of valley floor width to valley height (Vf) have been analyzed. Results of the former two are consistent with the tectonic landforms developed in thrust zones. Paleochannels of the Dabka and Baur rivers are characterized by high Vf values while other valleys show low Vf values. Quaternary alluvial sediments have been deformed along the Pawalgarth Thrust, a splay of the HFT. Deformation has resulted in the formation of the Pawalgarh Anticline, a thrust-related asymmetric fold.

  11. New insights into fault activation and stress transfer between en echelon thrusts: The 2012 Emilia, Northern Italy, earthquake sequence

    Cheloni, D.; Giuliani, R.; D'Agostino, N.; Mattone, M.; Bonano, M.; Fornaro, G.; Lanari, R.; Reale, D.; Atzori, S.

    2016-06-01

    Here we present the results of the inversion of a new geodetic data set covering the 2012 Emilia seismic sequence and the following 1 year of postseismic deformation. Modeling of the geodetic data together with the use of a catalog of 3-D relocated aftershocks allows us to constrain the rupture geometries and the coseismic and postseismic slip distributions for the two main events (Mw 6.1 and 6.0) of the sequence and to explore how these thrust events have interacted with each other. Dislocation modeling reveals that the first event ruptured a slip patch located in the center of the Middle Ferrara thrust with up to 1 m of reverse slip. The modeling of the second event, located about 15 km to the southwest, indicates a main patch with up to 60 cm of slip initiated in the deeper and flatter portion of the Mirandola thrust and progressively propagated postseismically toward the top section of the rupture plane, where most of the aftershocks and afterslip occurred. Our results also indicate that between the two main events, a third thrust segment was activated releasing a pulse of aseismic slip equivalent to a Mw 5.8 event. Coulomb stress changes suggest that the aseismic event was likely triggered by the preceding main shock and that the aseismic slip event probably brought the second fault closer to failure. Our findings show significant correlations between static stress changes and seismicity and suggest that stress interaction between earthquakes plays a significant role among continental en echelon thrusts.

  12. Active thrust faulting offshore Boumerdes, Algeria, and its relations to the 2003 Mw 6.9 earthquake

    Déverchère, J.; Yelles, K.; Domzig, A.; Mercier de Lépinay, B.; Bouillin, J.-P.; Gaullier, V.; Bracène, R.; Calais, E.; Savoye, B.; Kherroubi, A.; Le Roy, P.; Pauc, H.; Dan, G.

    2005-02-01

    We investigate the active seismogenic fault system in the area of the 2003 Mw 6.9 Boumerdes earthquake, Algeria, from a high-resolution swath bathymetry and seismic survey. A series of 5 main fault-propagation folds ~20-35 km long leave prominent cumulative escarpments on the steep slope and in the deep basin. Fault activity creates Plio-Quaternary growth strata within uplifted areas such as a rollover basin on the slope and piggyback basins in the deep ocean. Most thrusts turn to fault-propagation folds at the sub-surface and depict ramp-flat trajectories. We find that the two main slip patches of the 2003 Mw 6.9 Boumerdes earthquake are spatially correlated to two segmented cumulative scarps recognized on the slope and at the foot of the margin. The overall geometry indicates the predominance of back thrusts implying underthrusting of the Neogene oceanic crust.

  13. Active tectonics and rheology of slow-moving thrusts in the Tibetan foreland of peninsular India

    Copley, Alex; Mitra, Supriyo; Sloan, Alastair; Gaonkar, Sharad; Avouac, Jean-Philippe; Hollingsworth, James

    2016-04-01

    Peninsular India is cut by active thrust faults that break in earthquakes in response to the compressive force exerted between India and the Tibetan Plateau. The rate of deformation is low, with 2 +/- 1 mm/yr of shortening being accommodated over the entire N-S extent of the Indian sub-continent. However, the large seismogenic thickness in the region (40-50 km), and the long faults, mean that the rare earthquakes that do occur can have magnitudes up to at least 8. This contribution describes studies of two large Indian earthquakes, and their rheological and hazard implications, using a range of techniques. First, the Mw 7.6 Bhuj (Gujarat) earthquake of 2001 is examined using a combination of seismology, InSAR, and levelling data. A slip model for the earthquake will be presented, which allows the material properties of the fault plane to be examined. Second, a Holocene-age earthquake rupture from central India will be discussed. Geomorphic analysis of the scarps produced by the event suggest a magnitude of 7.6 - 8.4. Both of these earthquakes had unusually large stress-drops, amongst the largest recorded for shallow earthquakes. The information provided by these two events will be combined with calculations for the total compressive force being transmitted through the Indian peninsular in order to suggest that the faults are characterised by a low coefficient of friction (approximately 0.1), and that the stress-drops in the earthquakes are close to complete. In turn, these results imply that the majority of the force being transmitted through the Indian plate is supported by the brittle crust. Finally, the along-strike continuation of the faults will be described, with implications for hazard assessment and material properties throughout India.

  14. Geometry and development of the Jhajara thrust: An example of neotectonic activity in the Pinjaur Dun, NW Himalaya

    Singh, Vimal; Tandon, SK.; Singh, Vaibhava; Mukul, Malay; Thamó-Bozsó, Edit

    2008-01-01

    Mountain fronts of orogenic belts are marked by dynamic landscape changes under the influence of contemporary tectonic activity. Longitudinal valleys (locally called as Duns) constitute important landforms associated with some segments of the Himalayan mountain front. A neotectonic feature – the Jhajara thrust, has been identified in the Pinjaur Dun of NW Himalaya on the basis of structural mapping and tectonic geomorphological analysis. Optically stimulated luminescence dating on quartz sand...

  15. Short-lived tectonic switch mechanism for long-term pulses of volcanic activity after mega-thrust earthquakes

    M. Lupi

    2013-06-01

    Full Text Available Eruptive rates in volcanic arcs increase significantly after mega-thrust earthquakes in subduction zones. Over short to intermediate time periods the link between mega-thrust earthquakes and arc response can be attributed to dynamic triggering processes or static stress changes, but a fundamental mechanism that controls long-term pulses of volcanic activity after mega-thrust earthquakes has not been proposed yet. Using geomechanical, geological, and geophysical arguments, we propose that increased eruption rates over longer timescales are due to the relaxation of the compressional regime that accompanies mega-thrust subduction zone earthquakes. More specifically, the reduction of the horizontal stress σh promotes the occurrence of short-lived strike-slip kinematics rather than reverse faulting in the volcanic arc. The relaxation of the pre-earthquake compressional regime facilitates magma mobilization by providing a short-circuit pathway to shallow depths by significantly increasing the hydraulic properties of the system. The timescale for the onset of strike-slip faulting depends on the degree of shear stress accumulated in the arc during inter-seismic periods, which in turn is connected to the degree of strain-partitioning at convergent margins. We performed Coulomb stress transfer analysis to determine the order of magnitude of the stress perturbations in present-day volcanic arcs in response to five actual mega-thrust earthquakes; the 2005 M8.6, 2007 M8.5, and 2007 M7.9 Sumatra earthquakes; the 2010 M8.8 Maule, Chile earthquake; and the 2011 M9.0 Tohoku, Japan earthquake. We find that all, but one, the shallow earthquakes that occurred in the arcs of Sumatra, Chile and Japan show a marked lateral component. Our hypothesis suggests that the long-term response of volcanic arcs to subduction zone mega-thrust earthquakes will be manifested as predominantly strike-slip seismic events, and that these future earthquakes will be followed closely by

  16. Active fold-thrust belts in the foreland of eastern Tibet, the Longquan and Xiongpu anticlines in Sichuan, China

    Lee, Jian-Cheng; Chan, Yu-Chang; Lu, Chia-Yu; Chen, Chih-Tung; Chu, Hao-Tsu; Liu, Yuiping; Li, Jianzhong

    2016-04-01

    The 2008 M7.9 Wenchuan earthquake ruptured from the Longmenshan fault system, which is the frontal thrust system in eastern Tibet. Further east toward the foreland area in the Sichuan basin, it sits two anticlinal structures, the Longquan and Xiongpu anticlines, which trends sub-parallel to the Longmenshan range with a distance of about 70-100 km to the mountain front. It is widely considered that these two anticlinal features are attributed to propagation of the eastward extrusion of the eastern Tibetan plateau, similar to the stress system the Wenchuan earthquake. In this study, we carried out field investigations on these two active anticlinal structures in order to characterize the bulk deformation of the anticlines. We also conducted fracture analysis and fault-slip data analysis, in an attempt to characterize the fracture developments of the rock and the paleostress states related to the faulting events associated growth of the anticlines. We thus constructed a series of geological cross sections along these two anticlines. Our results show that the Longquan anticline is characterized by pop up structure with a dominant west-vergent thrust (i.e., backthrust) on the western limb. On the other hand to the eastern limb, an east-vergent thrust only well developed in the middle part of the anticline and die out toward the north and the south. For the Xiongpu anticline, it is characterized by a pre-dominant west-vergent backthrust system without developing an east-vergent thrust. A strike-slip fault and a series of N-S-trending pop-up thrusts cut across the Xiongpu anticline indicate a rather complex stress system with two dominant compression directions, NW-SE and E-W, subsequently or alternatively affected the area. Finally, the fracture analysis revealed that 2-3 pre-dominant bedding-perpendicular fracture sets are commonly developed in the massive sandstone layers. Most of them seemingly are of the characteristics of the mode I open joint, without clear

  17. NASA Fixed Wing Project Propulsion Research and Technology Development Activities to Reduce Thrust Specific Energy Consumption

    Hathaway, Michael D.; DelRasario, Ruben; Madavan, Nateri K.

    2013-01-01

    This paper presents an overview of the propulsion research and technology portfolio of NASA Fundamental Aeronautics Program Fixed Wing Project. The research is aimed at significantly reducing the thrust specific fuel/energy consumption of notional advanced fixed wing aircraft (by 60 % relative to a baseline Boeing 737-800 aircraft with CFM56-7B engines) in the 2030-2035 time frame. The research investments described herein are aimed at improving propulsive efficiency through higher bypass ratio fans, improving thermal efficiency through compact high overall pressure ratio gas generators, and exploring the potential benefits of boundary layer ingestion propulsion and hybrid gas-electric propulsion concepts.

  18. An active footwall shortcut thrust revealed by seismic reflection profiling: a case study of the Futaba fault, northern Honshu, Japan

    Sato, Hiroshi; Ishiyama, Tatsuya; Kato, Naoko; Higashinaka, Motonori; Kurashimo, Eiji; Iwasaki, Takaya; Abe, Susumu

    2013-04-01

    The Futaba fault is located along the Pacific cast of southern part of Northern Honshu and continues at least 100 km. Based on tectonic morphological research, its central part show the active tectonic features. Due to the effect of M9 Tohoku Oki earthquake 2011, the evaluation of Coulomb stress changes on the fault surface is concerned for the assess of seismic hazards. To investigate the deep geometry of seismogenic source fault and basic crustal structure, we performed deep seismic reflection profiling along the 58-km-long seismic line across the Futaba fault. The seismic data were obtained using four vibroseis trucks and 1164 channel recorders. The seismic section portrays the half graben filled by 1000-m-thick lower Miocene fluvial sediments, suggesting that the Futaba fault reactivated as a west dipping normal fault during the early Miocene associated with opening of the Sea of Japan. On the hanging wall of the Miocene normal fault, Mesozoic metamorphic rocks are cropping out forming a narrow range parallel to the fault. On the footwall of this range, footwall shortcut thrust is clearly identified by the deformation of Plio-Pleistocene sediments on the seismic section. The deeper extension of the Futaba fault can be traced down to 4.5 seconds (TWT) and sub-horizontal reflectors are developed around 6-7 seconds (TWT). The dip angle of the Futaba fault in the seismogenic zone is about 45 degrees. The footwall shortcut thrust was formed at the shallow high-angle part of the Futaba fault as a low-angle (30 degrees) reverse fault. The formation of half graben is limited along the northern part of this fault system. The footwall shortcut thrust was developed along a 40-km-long segment only accompanied with the Miocene half graben. The southern segment of the surface trace of the Futaba fault suggests a straight geometry may represent a change in dip angle.

  19. Active Thrusting Offshore Mount Lebanon: Source of the Tsunamigenic A.D. 551 Beirut-Tripoli Earthquake

    Tapponnier, P.; Elias, A.; Singh, S.; King, G.; Briais, A.; Daeron, M.; Carton, H.; Sursock, A.; Jacques, E.; Jomaa, R.; Klinger, Y.

    2007-12-01

    On July 9, AD 551, a large earthquake, followed by a tsunami destroyed most of the coastal cities of Phoenicia (modern-day Lebanon). This was arguably one of the most devastating historical submarine earthquakes in the eastern Mediterranean. Geophysical data from the Shalimar survey unveils the source of this Mw=7.5 event: rupture of the offshore, hitherto unknown, 100?150 km-long, active, east-dipping Mount Lebanon Thrust (MLT). Deep-towed sonar swaths along the base of prominent bathymetric escarpments reveal fresh, west facing seismic scarps that cut the sediment-smoothed seafloor. The MLT trace comes closest (~ 8 km) to the coast between Beirut and Enfeh, where as 13 radiocarbon-calibrated ages indicate, a shoreline-fringing Vermetid bench suddenly emerged by ~ 80 cm in the 6th century AD. At Tabarja, the regular vertical separation (~ 1 m) of higher fossil benches, suggests uplift by 3 more comparable-size earthquakes since the Holocene sea-level reached a maximum ca. 7-6 ka, implying a 1500?1750 yr recurrence time. Unabated thrusting on the MLT likely orchestrated the growth of Mt. Lebanon since the late Miocene. The newly discovered MLT has been the missing piece in the Dead Sea Transform and eastern Mediterranean tectonic scheme. Identifying the source of the AD 551 event thus ends a complete reassessment of the sources of the major historical earthquakes on the various faults of the Lebanese Restraining Bend of the Levant Fault System (or Dead Sea Transform).

  20. Neotectonics and structure of the Himalayan deformation front in the Kashmir Himalaya, India: Implication in defining what controls a blind thrust front in an active fold-thrust belt

    Gavillot, Y. G.; Meigs, A.; Yule, J. D.; Rittenour, T. M.; Malik, M. O. A.

    2014-12-01

    Active tectonics of a deformation front constrains the kinematic evolution and structural interaction between the fold-thrust belt and most-recently accreted foreland basin. In Kashmir, the Himalayan Frontal thrust (HFT) is blind, characterized by a broad fold, the Suruin-Mastargh anticline (SMA), and displays no emergent faults cutting either limb. A lack of knowledge of the rate of shortening and structural framework of the SMA hampers quantifying the earthquake potential for the deformation front. Our study utilized the geomorphic expression of dated deformed terraces on the Ujh River in Kashmir. Six terraces are recognized, and three yield OSL ages of 53 ka, 33 ka, and 0.4 ka. Vector fold restoration of long terrace profiles indicates a deformation pattern characterized by regional uplift across the anticlinal axis and back-limb, and by fold limb rotation on the forelimb. Differential uplift across the fold trace suggests localized deformation. Dip data and stratigraphic thicknesses suggest that a duplex structure is emplaced at depth along the basal décollement, folding the overlying roof thrust and Siwalik-Muree strata into a detachment-like fold. Localized faulting at the fold axis explains the asymmetrical fold geometry. Folding of the oldest dated terrace, suggest that rock uplift rates across the SMA range between 2.0-1.8 mm/yr. Assuming a 25° dipping ramp for the blind structure on the basis of dip data constraints, the shortening rate across the SMA ranges between 4.4-3.8 mm/yr since ~53 ka. Of that rate, ~1 mm/yr is likely absorbed by minor faulting in the near field of the fold axis. Given that Himalaya-India convergence is ~18.8-11 mm/yr, internal faults north of the deformation front, such as the Riasi thrust absorbs more of the Himalayan shortening than does the HFT in Kashmir. We attribute a non-emergent thrust at the deformation front to reflect deformation controlled by pre-existing basin architecture in Kashmir, in which the thick succession

  1. Active emergent thrust associated with a detachment fold: A case study of the eastern boundary fault of Takada plain, central Japan

    Kato, N.; Ishiyama, T.; Sato, H.; Saito, H.; Kurashimo, E.; Abe, S.

    2012-04-01

    To estimate seismic hazards, understanding the relationship between active fault and seismic source fault is crucial. Along the Japan Sea coast of Northern Honshu, Japan, thick sediments, deposited in the Miocene rift-grabens, formed fold-and-thrust belt, due to the shortening deformation since the Pliocene time. Most of the thrusts are active and show clear geomorphological evidences. Some of the thrusts are secondary faults, produced by the folding of competent layers. To elucidate the relationship between an emergent thrust and deep-sited seismogenic source fault, we performed shallow high-resolution seismic reflection profiling across the eastern boundary fault of the Takada plain, central Japan. Based on the moropho-tectonic data, the vertical slip rate of the Eastern boundary fault of the Takada plain is 0.9 mm/y and has potential to produce M7.2 earthquake (AIST, 2006). For shallow structure, we obtained CMP-seismic reflection data from a 7-km-long seismic line, using 541 channels of off-line recorders. Seismic source was an Envirovibe (IVI). Receiver and shot intervals are 12.5 m and seismic signals were recorded by fixed channels. Shallow seismic data were acquired as a piggy-bag project of 70 km-long onshore-offshore deep seismic profiling. High-resolution seismic section portrays the emergent thrust, dipping to the east at about 30 degrees. The hanging wall consist Pliocene interbedded mudstone and sandstone and deeper extension of the thrust can be traced down to the Miocene mudstone of the Teradoamri Formation as a low-angle fault. In the Niigata basin, the lower part of the Teradomari Formation is known as over pressured mudstone and shallow detachments are commonly developed in this unit. Based on the deep seismic section, including velocity profile obtained by refraction tomography, deep sited fault does not connect to the shallow active fault directly.

  2. Polyphase evolution of the Chaîne des Matheux frontal thrust (Haiti)

    Wessels, Richard; Ellouz-Zimmermann, Nadine; Rosenberg, Claudio; Bellahsen, Nicolas; Hamon, Youri; Deschamps, Remy; Battani, Anne; Leroy, Sylvie; Momplaisir, Roberte

    2016-04-01

    The NW - SE trending Haitian fold-and-thrust belt (HFTB) is located in the western part of the Caribbean island of Hispaniola. It covers the suture between the Cretaceous Caribbean island arc in the north and the Late Cretaceous thickened oceanic crust in the south. The HFTB is bounded to the north and south by the left-lateral Septentrional (SFZ) and Enriquillo-Plantain Garden (EPGFZ) fault zones, respectively. Compressional deformation on the HFTB commenced as early as Eocene times. It was followed by transpressional deformation from the early Miocene onwards, with in sequence progressive stacking of thrust sheets towards the SW. Seismicity at the junction between the HFTB and the EPGFZ is recorded by the 12 January 2010 Mw 7.0 earthquake. Surface mapping did not reveal a rupture, as the main activity occurred on the steep NNW dipping oblique transpressional Léogâne fault, while aftershocks documented motion on a shallow SW dipping thrust segment. The structural style of deformation of the HFTB, either the stacking of thrust sheets on basement heterogeneities or basement-involved thrusting, has not been studied in detail. Also lacking are conceptual models addressing the amount of convergence between the northern and southern domains, and describing how convergence was accommodated. To address these problems we conducted a detailed fieldwork on the southernmost thrust sheet, known as the Chaîne des Matheux front. Using stratigraphy, geological mapping, cross sections, kinematic fault slip data, analysis of mineralizations and fluid inclusions, and geochemical analysis of fluid seeps, we decipher the evolution of this anticlinal structure. Stratigraphic data reveal stable Eocene platform sedimentation over the whole region, which preceded deepening of the basin throughout Oligocene and early Miocene times. A diachronous evolution is evident from the middle Miocene onwards. The NE flank displays a shallowing upwards trend and clastic sedimentation, while the

  3. Geometry and modeling of an active offshore thrust-related fold system: the Amendolara Ridge, Ionian Sea, southern Italy

    L. Ferranti; Pepe, F.; P. Burrato; Santoro, E.; Mazzella, ME; Morelli, D; Passaro S; G. Vannucci

    2012-01-01

    On the Ionian Sea coast of southern Italy, spanning the transition from the Calabrian Arc to the Apennines, NE-directed motion of the thin-skinned frontal thrust belt of the Apennines toward the Apulian foreland reportedly ceased during the Early-Middle Pleistocene. The submarine extension of the frontal thrust belt is represented by the Amendolara ridge, which stretches for over 80 km to the SE beneath the Taranto Gulf. High-resolution marine geophysical data collected on the Amendolara ridg...

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

    Ashpis, David E.; Laun, Matthew C.

    2014-01-01

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

  5. Geological and geophysical evidences of late Quaternary activity of the range-front fault along the mid-segment of the Longmen Shan thrust belt

    Ren, J.; Xu, X.; Sun, X.; Tan, X.; Li, K.; Kang, W.; Liu, B.

    2011-12-01

    The Longmen Shan fault zone consists of three main Longmen Shan faults and the blind fault in the Chengdu Basin. Along the range front of the middle segment of the Longmen Shan, there is the lithological border in published geological maps. The existence and the latest active time of the range-front fault along the mid-segment of the Longmen Shan thrust belts are controversial for a long period. Petroleum seismic reflection and high-resolution shallow seismic reflection profile discovered the existence of the range-front fault and the fault offset the Quaternary strata. Based on detailed field observation, we found that there is an obvious linear feature along the mid-segment of the Longmen Shan front and the range-front fault displaced the late Quaternary fluvial terrace. Trench log indicates that a surface-rupture event occurred before ~1500a along the range-front fault. Differential GPS surveying and dating of fluvial terrace show that the range-front fault during late Quaternary underwent a vertical slip rate of bigger than 0.36mm/a, approximately equivalent to that along the main faults of the longmen Shan thrust belts, which demonstrates that the range-front fault also took an important role in accommodating the deformation of the Longmen Shan thrust zone. This study not only provides the fundamental data for seismic hazard assessment of the Chengdu Plain, but is helpful for the overall understanding of uplift mechanism of east Tibet.

  6. Active thrust faulting offshore Boumerdes, Algeria, and its relations to the 2003 Mw 6.9 earthquake - art. no. L043111

    Deverchere, Jacques; Yelles, K.; Domzig, Anne; Mercier de Lepinay, B.; Bouillin, J.p.; Gaullier, V.; Bracene, R.; Calais, E.; Savoye, Bruno; A. Kherroubi; Le Roy, P.; Pauc, H; Dan, Gabriela

    2005-01-01

    [1] We investigate the active seismogenic fault system in the area of the 2003 Mw 6.9 Boumerdes earthquake, Algeria, from a high-resolution swath bathymetry and seismic survey. A series of 5 main fault-propagation folds similar to20-35 km long leave prominent cumulative escarpments on the steep slope and in the deep basin. Fault activity creates Plio-Quaternary growth strata within uplifted areas such as a rollover basin on the slope and piggyback basins in the deep ocean. Most thrusts turn t...

  7. Variable thrust cartridge

    Taleyarkhan, Rusi P.

    2000-11-07

    The present invention is a variable thrust cartridge comprising a water-molten aluminum reaction chamber from which a slug is propelled. The cartridge comprises a firing system that initiates a controlled explosion from the reaction chamber. The explosive force provides a thrust to a slug, preferably contained within the cartridge.

  8. Exploring the shallow structure of the San Ramón thrust fault in Santiago, Chile (∼33.5° S, using active seismic and electric methods

    D. Díaz

    2014-01-01

    Full Text Available The crustal-scale west-vergent San Ramón thrust fault system at the foot of the main Andean Cordillera in central Chile is a geologically active structure with Quaternary manifestations of complex surface rupture along fault segments in the eastern border of Santiago city. From the comparison of geophysical and geological observations, we assessed the subsurface structure pattern affecting sedimentary cover and rock-substratum topography across fault scarps, which is critic for evaluating structural modeling and associated seismic hazard along this kind of faults. We performed seismic profiles with an average length of 250 m, using an array of twenty-four geophones (GEODE, and 25 shots per profile, supporting high-resolution seismic tomography for interpreting impedance changes associated to deformed sedimentary cover. The recorded traveltime refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both velocities and reflections interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps supported subsurface resistivity tomographic profiles, which revealed systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, clearly limited by well-defined east-dipping resistivity boundaries. The latter can be interpreted in terms of structurally driven fluid content-change between the hanging wall and the footwall of a permeability boundary associated with the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ∼55° E at subsurface levels in piedmont sediments, with local complexities being probably associated to fault surface rupture propagation

  9. Radon concentration in drinking water sources of the region adjacent to a tectonically active Karak Thrust, southern Kohat Plateau, Khyber Pakhtunkhwa, Pakistan

    A total of 84 drinking water samples from tube wells, natural springs, hand pumps and open wells in the region adjacent to a tectonically active Karak Thrust, Pakistan, were analyzed for radon content determination. These samples have a mean, maximum and minimum radon values of 9.4 ± 0.4, 25.1 ± 0.9, and 1.1 ± 0.2 Bq l-1, respectively. This study indicates that 24 % of samples from tube wells, 44 % from springs, and 50 % from hand pumps have radon levels in excess of the EPA recommended maximum contaminant level of 11.1 Bq l-1. The mean annual effective doses of all the samples are lower than the reference level of 0.1 mSv a-1. Drinking water from majority of the sources within the region is generally safe as far as radon related health hazards are concerned with exception of few isolated cases. (author)

  10. InSAR Evidence for an active shallow thrust fault beneath the city of Spokane Washington, USA

    Wicks, Charles W., Jr.; Weaver, Craig S.; Bodin, Paul; Sherrod, Brian

    2013-01-01

    In 2001, a nearly five month long sequence of shallow, mostly small magnitude earthquakes occurred beneath the city of Spokane, a city with a population of about 200,000, in the state of Washington. During most of the sequence, the earthquakes were not well located because seismic instrumentation was sparse. Despite poor-quality locations, the earthquake hypocenters were likely very shallow, because residents near the city center both heard and felt many of the earthquakes. The combination of poor earthquake locations and a lack of known surface faults with recent movement make assessing the seismic hazards related to the earthquake swarm difficult. However, the potential for destruction from a shallow moderate-sized earthquake is high, for example Christchurch New Zealand in 2011, so assessing the hazard potential of a seismic structure involved in the Spokane earthquake sequence is important. Using interferometric synthetic aperture radar (InSAR) data from the European Space Agency ERS2 and ENVISAT satellites and the Canadian Space Agency RADARSAT-1, satellite we are able to show that slip on a shallow previously unknown thrust fault, which we name the Spokane Fault, is the source of the earthquake sequence. The part of the Spokane Fault that slipped during the 2001 earthquake sequence underlies the north part of the city, and slip on the fault was concentrated between ~0.3 and 2 km depth. Projecting the buried fault plane to the surface gives a possible surface trace for the Spokane Fault that strikes northeast from the city center into north Spokane.

  11. Conjunction challenges of low-thrust geosynchronous debris removal maneuvers

    Anderson, Paul V.; Schaub, Hanspeter

    2016-06-01

    The conjunction challenges of low-thrust engines for continuous thrust re-orbiting of geosynchronous (GEO) objects to super-synchronous disposal orbits are investigated, with applications to end-of-life mitigation and active debris removal (ADR) technologies. In particular, the low maneuverability of low-thrust systems renders collision avoidance a challenging task. This study investigates the number of conjunction events a low-thrust system could encounter with the current GEO debris population during a typical re-orbit to 300 km above the GEO ring. Sensitivities to thrust level and initial longitude and inclination are evaluated, and the impact of delaying the start time for a re-orbiting maneuver is assessed. Results demonstrate that the mean number of conjunctions increases hyperbolically as thrust level decreases, but timing the start of the maneuver appropriately can reduce the average conjunction rate when lower thrust levels are applied.

  12. The Yakima Fold and Thrust Belt - a paradigm for active shortening in the Columbia embayment from Pasco to the Pacific Ocean (Invited)

    Wells, R. E.; Blakely, R. J.; Sherrod, B. L.; Weaver, C. S.

    2009-12-01

    The Yakima Fold Belt (YFB), a series of nearly east-west trending folds and associated thrusts, accommodates N-S shortening in the 16-6 Ma Columbia River Basalt Group (CRBG) and younger strata in the western Columbia Plateau. The folds are commonly asymmetric and north verging, with broad, south dipping back limbs and short, steep, fore-limbs. The YFB lies within the Columbia embayment, an oroclinal bend in the Mesozoic orogen between the Klamath Mountains and the North Cascades, long considered to be the result of northwest motion of California in late Cenozoic time. YFB-style deformation is not restricted to the YFB; it fans westward across the Cascades and is superimposed on the subduction-related arc, Puget-Willamette trough, and Coast Range. New geophysical data link the YFB across the Cascades to the active South Whidbey Island and Seattle Faults in the Puget Lowland, generally along the broadly defined Olympic-Wallowa Lineament (OWL). South of Puget Sound, the east-west Doty Fault, the Columbia River Syncline (controlling the location of the Columbia River across the Coast Range), and the post-CRBG folding in the northern Willamette Valley are all late Cenozoic YFB-related structures accommodating N-S shortening in the forearc. This geologic evidence indicates that the Columbia embayment is the locus of extensive post middle Miocene shortening, and there is abundant paleoseismic evidence for large Holocene earthquakes on these structures in Puget Lowland and in the YFB. Seismicity in the embayment is characterized by thrust and strike slip focal mechanisms, with P axes oriented approximately N-S. GPS results of McCaffrey et al. (2007) indicate that folding in the embayment is driven by the clockwise rotation of Oregon about a pole near the OR-WA-ID border, compressing Washington against slow-moving Canada. The folds fan westward from this pole of rotation, and shortening increases to the west to about 7.1 mm/yr between Astoria and Penticton, BC. Shortening

  13. The Formation of a Retroarc Fold-Thrust Belt by the Closure and Inversion of a Back-Arc Basin; Patagonian-Fuegian Fold-Thrust Belt, Chile

    Betka, P.; Klepeis, K. A.; Mosher, S.

    2012-12-01

    margin. A low taper triangle zone formed at the tip of the thrust wedge where Late Cretaceous strata of the foreland basin are backthrust (top-SE) above the shale decollement. Several NE-vergent thrusts sole into the shale decollement and imbricate foreland basin strata. Shortening in the basement beneath the lower decollement is detached from the cover and accommodated by polyphase folding and penetrative strain. A minimum of ~9 km (15%) of shortening is transferred into the FTB during this stage. The second stage is marked by basement involved, steeply dipping (>60°) reverse faults that cut the initial decollements. One high-angle reverse fault places basement and RVB rocks above the foreland basin strata and can be traced for >100 km along strike. Two other basement involved reverse faults cut early phase structures of the retroarc FTB. On the basis of steep dip, and the cross cutting relationship with the early decollements, basement-involved reverse faults are interpreted to reactivate Jurassic normal faults. Thick-skinned faulting accounts for a minimum of ~4 km (7%) shortening. The Patagonian-Fuegian FTB provide an important example of how decollement levels and structural style of a retroarc FTB can be controlled by the inherited stratigraphic architecture and structure of a back-arc basin in a noncollisional setting.

  14. Thin-Film Strain Gauge Sensors for Ion Thrust Measurement

    Stephen, John R.; Rajanna, K.; Dhar, Vivek; Kumar, Kalyan KG; Nagabushanam, S

    2004-01-01

    In order to measure the thrust produced by a Stationary Plasma Thruster, a measurement system has been developed using a thrust balance with thin film strain gauge sensors. For this purpose, strain gauges were designed and deposited on the columns of the thrust balance fabricated and necessary signal conditioning circuit has been used. Performance of the system developed was studied, in a vacuum chamber under space simulated conditions, by activating the thruster. In-situ calibration was done...

  15. Role of wing morphing in thrust generation

    Mehdi Ghommem

    2014-01-01

    Full Text Available In this paper, we investigate the role of morphing on flight dynamics of two birds by simulating the flow over rigid and morphing wings that have the characteristics of two different birds, namely the Giant Petrel and Dove Prion. The simulation of a flapping rigid wing shows that the root of the wing should be placed at a specific angle of attack in order to generate enough lift to balance the weight of the bird. However, in this case the generated thrust is either very small, or even negative, depending on the wing shape. Further, results show that morphing of the wing enables a significant increase in the thrust and propulsive efficiency. This indicates that the birds actually utilize some sort of active wing twisting and bending to produce enough thrust. This study should facilitate better guidance for the design of flapping air vehicles.

  16. Recommended Practices in Thrust Measurements

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

    2013-01-01

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

  17. High Rate Data Delivery Thrust Area

    Bhasin, Kul

    2000-01-01

    In this paper, a brief description of the high rate data delivery (HRDD) thrust area, its focus and current technical activities being carried out by NASA centers including JPL, academia and industry under this program is provided. The processes and methods being used to achieve active participation in this program are presented. The developments in space communication technologies, which will shape NASA enterprise missions in the 21 st. century, are highlighted.

  18. Early Cenozoic Multiple Thrust in the Tibetan Plateau

    Zhenhan Wu

    2013-01-01

    Full Text Available Recently completed regional geological mapping at a scale of 1 : 250,000 or larger across all of the Tibetan Plateau coupled with deep seismic surveys reveals for the first time a comprehensive depiction of the major early Cenozoic thrust systems resulting from the northward subduction of the Indian Continental Plate. These systems define a series of overlapping north-dipping thrust sheets that thickened the Tibetan crust and lead to the rise of the plateau. The few south-dipping thrusts present apparently developed within a sheet when the back moved faster than the toe. Many of the thrusts are shown to extend to the middle-lower crustal depths by seismic data. The regional thrust systems are the Main Central, Renbu-Zedong, Gangdese, Central Gangdese, North Gangdese, Bangoin-Nujiang, Qiangtang, Hohxil, and South Kunlun Thrusts. The minimal southward displacements of the South Kunlun, Hohxil, South Qiangtang, and Central Gangdese Thrusts are estimated to be 30 km, 25 km, 150 km and 50 km, respectively. Deep thrusting began in the Himalaya-Tibetan region soon after India-Eurasia continental collision and led to crustal thickening and subsequent uplift of the Tibetan Plateau during Late Eocene-Early Miocene when the systems were mainly active. The major thrust systems ceased moving in Early Miocene and many were soon covered by lacustrine strata. This activity succeeded in the late Cenozoic to crustal extension and strike-slip movement in the central Tibetan Plateau. The revelation of the full array of the early Cenozoic thrust systems provides a much more complete understanding of the tectonic framework of the Tibetan Plateau.

  19. Aircraft Horizontal Thrust Measurement Facility

    Federal Laboratory Consortium — This facility is designed to support the DoD mission by providing unique air vehicle installed engine performance (thrust output) measurements. This system consists...

  20. Evaluation of fluidic thrust vectoring nozzle via thrust pitching angle and thrust pitching moment

    Li, L.; Hirota, M.; Ouchi, K.; Saito, T.

    2016-03-01

    Shock vector control (SVC) in a converging-diverging nozzle with a rectangular cross-section is discussed as a fluidic thrust vectoring (FTV) method. The interaction between the primary nozzle flow and the secondary jet is examined using experiments and numerical simulations. The relationships between FTV parameters [nozzle pressure ratio (NPR) and secondary jet pressure ratio (SPR)] and FTV performance (thrust pitching angle and thrust pitching moment) are investigated. The experiments are conducted with an NPR of up to 10 and an SPR of up to 2.7. Numerical simulations of the nozzle flow are performed using a Navier-Stokes solver with input parameters set to match the experimental conditions. The thrust pitching angle and moment computed from the force-moment balance are used to evaluate FTV performance. The experiment and numerical results indicate that the FTV parameters (NPR and SPR) directly affect FTV performance. Conventionally, FTV performance evaluated by the common method using thrust pitching angle is highly dependent on the location of evaluation. Hence, in this study, we show that the thrust pitching moment, a parameter which is independent of the location, is the appropriate figure of merit to evaluate the performance of FTV systems.

  1. Coseismic displacements and Holocene slip rates for two active thrust faults at the mountain front of the Andean Precordillera (˜33°S)

    Schmidt, Silke; Hetzel, Ralf; Mingorance, Francisco; Ramos, Victor A.

    2011-10-01

    During the last few hundred years several destructive earthquakes occurred along the eastern margin of the Andean Precordillera, where GPS data reveal a shortening rate of ˜4.5 mm/a. We use fault scarp profiles and age determinations of deformed terraces (T1-T4) to infer coseismic displacements and quantify slip rates for the Peñas and Cal thrust faults near Mendoza city. Scarps on the lowest terrace level T1 reveal vertical offsets of 0.8-1.0 m for both faults, which are interpreted as coseismic displacements during the last earthquake. Together with the fault dip these offsets indicate that both faults are capable of producing magnitude MW ˜6.9 earthquakes, which is corroborated by a magnitude MS = 7.0 event on the Cal fault that destroyed Mendoza in 1861. At the Peñas thrust fault, terrace T2 has an age of ˜3.3 ka and is offset by ˜1.9 m, whereas the ˜12-ka-old terrace T3 is displaced by ˜11 m. Combined with the fault dip of ˜25°, the age and offset of terrace T3 define a shortening rate of ˜2.0 mm/a on the Peñas fault, i.e., about half of the present-day shortening at the eastern margin of the Precordillera. At the Cal fault, terraces T2 to T4 have ages of ˜0.8 ka (OSL), ˜3.9 ka (14C), and ≤12 ka (10Be) and are vertically offset by ˜2.6, ˜3.6, and ˜7.0 m, respectively, which implies that slip on the fault has recently accelerated. Hence, the Cal fault poses a serious seismic hazard to the one million inhabitants of Mendoza.

  2. Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators

    Ashpis, David E.; Laun, Matthew C.

    2013-11-01

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

  3. Polyphase thrust tectonic in the Barberton greenstone belt

    Paris, I. A.

    1986-01-01

    In the circa 3.5 by-old Barberton greenstone belt, the supracrustal rocks form a thick and strongly deformed thrust complex. Structural studies in the southern part of the belt have shown that 2 separate phases of over-thrusting (D sub 1 and D sub 2) successively dismembered the original stratigraphy. Thrust nappes were subsequently refolded during later deformations (D sub 3 and D sub 4). This report deals with the second thrusting event which, in the study region appears to be dominant, and (unlike the earlier thrusting), affects the entire supracrustal pile. The supracrustal rocks form a predominantly NE/SW oriented, SE dipping tectonic fan (the D sub 2 fan) in which tectonic slices of ophiolitic-like rocks are interleaved with younger sedimentary sequences of the Diepgezet and malalotcha groups. Structural and sedimentological data indicate that the D sub 2 tectonic fan was formed during a prolonged, multi-stage regional horizontal shortening event during which several types of internal deformation mechanisms were successively and/or simultaneously active. Movement appears to have been predominantly to the NW and to the N. During D sub 2, periods of quiescence and sedimentation followed periods of thrust propagation. Although the exact kinematics which led to the formation of this fan is not yet known, paleoenvironmental interpretations together with structural data suggest that D sub 2 was probably related to (an) Archean collision(s).

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

    Ashpis, David E.; Laun, Matthew C.

    2014-01-01

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

  5. High Thrust-Density Electrostaic Engines Project

    National Aeronautics and Space Administration — These issues are addressable by: increasing the thrust, power, and thrust-to-power ratio capability of EP systems; reducing the non-recurring engineering systems...

  6. Studies on Thrust Characteristic of High-Thrust Spiral Motor

    Kominami, Tsutomu; Fujimoto, Yasutaka

    Linear actuators are used in various industrial applications. Connentional linear actuators are a combination of a rotational motor and a ball screw, a hydraulic actuator, or a linear motor. However, these actuators have some demerits. This paper proposes a spiral motor (SPRM) that comprises a spiral stator and a spiral mover. Owing to its spiral structure, the SPRM can be expected to show better performance as compared to the conventional linear actuator. However, it is not easy to manufacture spiral stators and spiral movers. In this paper, thrust and torque equations derived from a magnetic circuit are introduced. A prototype is developed and its specifications are provided. Sixty fan-shaped stator blocks are mounted on the frame and forty-eight fan-shaped mover blocks with flat surfaces are mounted on the axis. These blocks form an approximately spiral structure. The blocks are not difficult to manufacture. The feasibility of the developed SPRM is confirmed by performing basic experiments. First, the SPRM is driven by using synchronous control. Subsequently, the thrust is measured by a load cell and the thrust constant is determined.

  7. Nonlinear dynamics of a vectored thrust aircraft

    Sørensen, C.B; Mosekilde, Erik

    1996-01-01

    With realistic relations for the aerodynamic coefficients, numerical simulations are applied to study the longitudional dynamics of a thrust vectored aircraft. As function of the thrust magnitude and the thrust vectoring angle the equilibrium state exhibits two saddle-node bifurcations and three...

  8. Nonlinear dynamics of a vectored thrust aircraft

    Sørensen, C.B; Mosekilde, Erik

    With realistic relations for the aerodynamic coefficients, numerical simulations are applied to study the longitudional dynamics of a thrust vectored aircraft. As function of the thrust magnitude and the thrust vectoring angle the equilibrium state exhibits two saddle-node bifurcations and three...

  9. Summarization on variable liquid thrust rocket engines

    2009-01-01

    The technology actuality and development trend of variable thrust rocket engines at home and abroad are summarized. Key technologies of developing variable thrust rocket engines are analyzed. Development advices on developing variable thrust rocket engines that are adapted to the situation of our country are brought forward.

  10. Engineering research, development and technology: Thrust area report FY 91

    The mission of the Engineering Research, Development, and Technology Program at Lawrence, Livermore National Laboratory (LLNL) is to develop the technical staff and the technology needed to support current and future LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) to identify key technologies and (2) conduct high quality work to enhance our capabilities in these key technologies. To help focus our efforts, we identify technology thrust areas and select technical leaders for each area. The thrust areas are integrated engineering activities and, rather than being based on individual disciplines, they are staffed by personnel from Electronics Engineering, Mechanical Engineering, and other LLNL organizations, as appropriate. The thrust area leaders are expected to establish strong links to LLNL program leaders and to industry; to use outside and inside experts to review the quality and direction of the work; to use university contacts to supplement and complement their efforts; and to be certain that we are not duplicating the work of others. The thrust area leader is also responsible for carrying out the work that follows from the Engineering Research, Development, and Technology Program so that the results can be applied as early as possible to the needs of LLNL programs. This annual report, organized by thrust area, describes activities conducted within the Program for the fiscal year, 1991. Its intent is to provide timely summaries of objectives, theories, methods, and results

  11. Robotic Pectoral Fin Thrust Vectoring Using Weighted Gait Combinations

    John S. Palmisano

    2012-01-01

    Full Text Available A method was devised to vector propulsion of a robotic pectoral fin by means of actively controlling fin surface curvature. Separate flapping fin gaits were designed to maximize thrust for each of three different thrust vectors: forward, reverse, and lift. By using weighted combinations of these three pre-determined main gaits, new intermediate hybrid gaits for any desired propulsion vector can be created with smooth transitioning between these gaits. This weighted gait combination (WGC method is applicable to other difficult-to-model actuators. Both 3D unsteady computational fluid dynamics (CFD and experimental results are presented.

  12. Thrust kinematics deduced by primary and secondary magnetizations in the Internal Sierras (Central Pyrenees, Spain)

    Oliva, B.; Pueyo, E.

    2003-04-01

    The Central Southern Pyrenees are composed (from N to S) by the Axial Zone (made by several basement-involved nappes; (Gavarnie and Guarga), the Internal Sierras (IS) fold and thrust belt (Larra and Monte Perdido units), the Jaca piggyback basin (turbiditic and molassic) and the External Sierras. Several paleomagnetic studies have been carried out during the last decades in all units except for the IS. Different amounts of rotation were reported, usually from primary directions. This work shows paleomagnetic results derived from recent investigations in the IS. 78 sites were sampled in different thrust sheets in the Larra and Monte Perdido units. Sites were collected in Upper Cretaceous rocks; all of them were homogeneously distributed along the range strike. A N-S section through the Eocene turbiditic basin was also done (9 sites) to link our results to previous data. Stepwise thermal demagnetization every 25-50^oC was performed to unravel the NRM components. Magnetic mineralogy essays (IRM, IST and low temperature) confirm magnetite as the major magnetic carrier. Two paleomagnetic components can be distinguished; A) an intermediate direction unblocking from 350^o to 450^oC and B) a high temperature component (from 500^o -575^oC). The B component displays two polarities and a positive fold and reverse tests whereas the A component shows only reverse polarity and a pervasive negative fold test. The A component has been also found in the Eocene transect. Two major clues help to constrain the remagnetization age; on one hand the deformation age (Early-Middle Eocene in the Larra and Monte Perdido units) and, on the other hand, the age of the turbiditic rocks (Middle Eocene). Therefore the remagnetization process took place by the end of the IS thrust system configuration or in a later period. Since the rotation detected by the A and B components are similar, the rotation age can be constrained as younger than the remagnetization. All these deductions have important

  13. Coupled thrust and vorticity dynamics during VRS

    Savas, O.; Green, R. B.; Caradonna, F.X.

    2008-01-01

    The focus is on the vortex ring state (VRS) observed at rapid descent rates. At VRS, the helical vortex filaments coming off the blades amalgamate around the rotor disk forming a vortex ring, which periodically detaches into the wake, causing extreme oscillations in thrust, with periods on the order of several tens of rotor revolutions. We discuss here the phase relation between the thrust cycle and vorticity distribution at the rotor disk. Maxima of the VRS thrust oscill...

  14. Interseismic deformation of the Montello thrust, northern Italy

    Finocchio, D.; Barba, S.; Burrato, P.; De Martini, P.

    2011-12-01

    The Montello Anticline belongs to the southernmost thrust units of the S-verging Eastern Southern Alps (ESA), at the edge of the Veneto-Friuli plain (North-eastern Italy). The present-day tectonic setting of the area results from the Northward motion and underthrusting of Adria microplate with respect to Europe. Deformed fluvial terraces and deflection of the Piave River suggest that the Montello is an active growing anticline. Based on surface geology of folded strata, topographic expression of the anticline and geophysical data, the Montello Thrust was characterized as a 30-km-long structure rooted at about 11 km depth. However, the real seismogenic potential of the thrust fault that drives the anticlinal uplift is still questioned. In fact, on the one hand geodetic data shows a N-S oriented ca. 1.5 mm/a active shortening across the outermost structures of this sector of the ESA, and geologic and geomorphic data constrain a Quaternary slip rate of 0.5-1.5 mm/a. On the other hand earthquake catalogues indicates a minimum of seismic moment release in the Montello area with respect to the otherwise seismogenic Veneto-Friuli belt. To test the possible seismogenic behavior of the Montello Thrust , we modeled interseismic geodetic data and geological markers through a finite element analysis. We developed a NW-SE trending, 60 km long and 40 km deep 2D grid crossing the Montello thrust at its leading edge. The displacement was computed assuming elastoplastic rheology and plane strain. We tested different plausible fault geometries, starting from existing interpreted seismic lines, and choose the best-fitting one by comparing the model prediction with terrestrial leveling data, horizontal GPS velocities (permanent stations), and attitude of the geological strata. In our model, two different rheological layers are separated by a N-dipping low-angle plane (3°) at 8 km depth, which represents the regional monocline. The upper layer is elastoplastic and the lower layer is

  15. Design and evaluation of thrust vectored nozzles using a multicomponent thrust stand

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

    1990-01-01

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

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

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

    2016-06-01

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

  17. Engineering Research, Development and Technology, FY95: Thrust area report

    NONE

    1996-02-01

    The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the knowledge base, process technologies, specialized equipment, tools and facilities to support current and future LLNL programs. Engineering`s efforts are guided by a strategy that results in dual benefit: first, in support of Department of Energy missions, such as national security through nuclear deterrence; and second, in enhancing the nation`s economic competitiveness through their collaboration with US industry in pursuit of the most cost-effective engineering solutions to LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) identify key technologies relevant to LLNL programs where they can establish unique competencies, and (2) conduct high-quality research and development to enhance their capabilities and establish themselves as the world leaders in these technologies. To focus Engineering`s efforts, technology thrust areas are identified and technical leaders are selected for each area. The thrust areas are comprised of integrated engineering activities, staffed by personnel from the nine electronics and mechanical engineering divisions, and from other LLNL organizations. This annual report, organized by thrust area, describes Engineering`s activities for fiscal year 1995. The report provides timely summaries of objectives methods, and key results from eight thrust areas: computational electronics and electromagnetics; computational mechanics; microtechnology; manufacturing technology; materials science and engineering; power conversion technologies; nondestructive evaluation; and information engineering.

  18. Mechanical Initiation and Propagation Mechanism of a Thrust Fault: A Case Study of the Yima Section of the Xiashi-Yima Thrust (North Side of the Eastern Qinling Orogen, China)

    Cai, Wu; Dou, Linming; Li, Zhenlei; He, Jiang; He, Hu; Ding, Yanlu

    2015-09-01

    Thrust faults exist extensively in nature, and their activities often cause earthquakes and disasters involving underground engineering, such as the May 12, 2008 Wenchuan Earthquake; the April 20, 2013 Ya'an Earthquake; and the Nov. 3, 2011 Yima Qianqiu Coal-Mining Accident in China. In this paper, the initiation and propagation of a thrust are discussed from a mechanical viewpoint using fault mechanics and fault-slip analysis, taking as an example the Yima section of the Xiashi-Yima thrust (north side of the eastern Qinling Orogen, China). The research primarily focuses on the stress field and the formation trajectory of the thrust and the genesis of the large-scale inversion thrust sheet. The results show that the thrust results from failures in the compressive deformation state and that its stress state is entirely compressive shear. The rupture trajectory of the thrust develops upward, and the fault fracture zone forms similarly to a listric fault, up-narrow and down-wide. The model results and the genesis of the large-scale inversion thrust sheet are consistent with in situ exploration observations. This investigation can be extended to other thrust faults with similar characteristics, particularly for the design of mining operations in tectonic-active areas. Moreover, this research can be used to further study the mechanism of thrust faults and provide support for the feasibility of using fault-slip analysis to assess fault stability.

  19. Thrust Area Report, Engineering Research, Development and Technology

    Langland, R. T.

    1997-02-01

    The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the knowledge base, process technologies, specialized equipment, tools and facilities to support current and future LLNL programs. Engineering`s efforts are guided by a strategy that results in dual benefit: first, in support of Department of Energy missions, such as national security through nuclear deterrence; and second, in enhancing the nation`s economic competitiveness through our collaboration with U.S. industry in pursuit of the most cost- effective engineering solutions to LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) identify key technologies relevant to LLNL programs where we can establish unique competencies, and (2) conduct high-quality research and development to enhance our capabilities and establish ourselves as the world leaders in these technologies. To focus Engineering`s efforts technology {ital thrust areas} are identified and technical leaders are selected for each area. The thrust areas are comprised of integrated engineering activities, staffed by personnel from the nine electronics and mechanical engineering divisions, and from other LLNL organizations. This annual report, organized by thrust area, describes Engineering`s activities for fiscal year 1996. The report provides timely summaries of objectives, methods, and key results from eight thrust areas: Computational Electronics and Electromagnetics; Computational Mechanics; Microtechnology; Manufacturing Technology; Materials Science and Engineering; Power Conversion Technologies; Nondestructive Evaluation; and Information Engineering. Readers desiring more information are encouraged to contact the individual thrust area leaders or authors. 198 refs., 206 figs., 16 tabs.

  20. Structural setting of the Apennine-Maghrebian thrust belt

    PieroElter; MarioGrasso; MaurizioParotto; LivioVezzani

    2003-01-01

    The Apennine-Maghrebian fold-and-thrust belt devel-oped from the latest Cretaceous to Early Pleistocene at the subduction-collisional boundary between the Euro-pean and the westward-subducted Ionian and Adria plates. Large parts of the Mesozoic oceanic lithosphere were subducted during an Alpine phase from the Late Cretaceous to Middle Eocene. The chain developed through the deformation of major paleogeographic internal domains (tectono-sedimentary sequences of the Ligurian-Piedmont Ocean) and external domains (sedi-mentary sequences derived from the deformation of the continental Adria-African passive mareinL The continu-ity of the Apennine chain is abruptly interrupted in the Calabrian Arc by the extensive klippe of Kabylo-Calabrian crystalline exotic terranes, derived from deformation of the European passive margin.Major complexities (sharp deflections in the arcuate configuration of the thrust belt, out-of-sequence propagation of the thrusts) are referred to contrasting rheology and differential buoyancy of the subducted lithosphere (transitional from conti-nental to oceanic) and consequent differential roll-back of the Adria plate margin, and to competence contrasts in the Mesozoic stratigraphic sequences,where multiple décollement horizons at different stratigraphic levels may have favored significant differential shortening.From the Late Miocene, the geometry of the thrust belt was strongly modified by extensional fault-ing, volcanic activity, crustal thinning and formation of oceanic crust correlated with the development of the Tyrrhenian Basin.

  1. Low thrust chemical rocket technology

    Schneider, Steven J.

    1992-01-01

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

  2. Insulated Engine, 100-Pound Thrust

    Roth, N. R.

    1966-01-01

    The design and test results of an insulated, 100-pound thrust engine capable of delivering high performance, providing long, steady state and pulse mode endurance, and maintaining a low outside surface temperature of 4000 F, are presented. Included are descriptions of the injector designs and insulation materials investigated, plus a discussion of the thermal analysis and test results. Continuous operation in excess of 29 minutes, and start capability in excess of 4900 pulses, have been demonstrated. To allow the use of available chamber materials and coating systems under insulated conditions, the major challenge to the designer was to define an injector design that would provide gas temperatures and performance of a predetermined value. The solution was the development of an unbalanced, 8-element triplet injector having an unequal fuel distribution within each element, capable of providing a specific impulse in excess of 290 pounds at reduced wall temperatures. The design consists of a columbium chamber and nozzle utilizing a silicide coating, a columbium injector, a composite insulation system of aluminum oxide

  3. Seismological evidence of an active footwall shortcut thrust in the Northern Itoigawa-Shizuoka Tectonic Line derived by the aftershock sequence of the 2014 M 6.7 Northern Nagano earthquake

    Panayotopoulos, Yannis; Hirata, Naoshi; Hashima, Akinori; Iwasaki, Takaya; Sakai, Shin'ichi; Sato, Hiroshi

    2016-06-01

    A destructive M 6.7 earthquake struck Northern Nagano prefecture on November 22, 2014. The main shock occurred on the Kamishiro fault segment of the northern Itoigawa-Shizuoka Tectonic Line (ISTL). We used data recorded at 41 stations of the local seismographic network in order to locate 2118 earthquakes that occurred between November 18 and November 30, 2014. To estimate hypocenters, we assigned low Vp models to stations within the Northern Fossa Magna (NFM) basin thus accounting for large lateral crustal heterogeneities across the Kamishiro fault. In order to further improve accuracy, the final hypocenter locations were recalculated inside a 3D velocity model using the double-difference method. We used the aftershock activity distribution and focal mechanism solutions of major events in order to estimate the source fault area of the main shock. Our analysis suggests that the shallow part of the source fault corresponds to the surface trace of the Kamishiro fault and dips 30°-45° SE, while the deeper part of the source fault corresponds to the downdip portion of the Otari-Nakayama fault, a high angle fault dipping 50°-65° SE that formed during the opening of the NFM basin in the Miocene. Along its surface trace the Otari-Nakayama fault has been inactive during the late Quaternary. We verified the validity of our model by calculating surface deformation using a simple homogeneous elastic half-space model and comparing it to observed surface deformation from satellite interferometry, assuming large coseismic slip in the areas of low seismicity and small coseismic slip in the areas of high seismicity. Shallowing of the source fault from 50°-65° to 30°-45° in the upper 4 km, in the areas where both surface fault traces are visible, is a result of footwall shortcut thrusting by the Kamishiro fault off the Otari-Nakayama fault.

  4. Performance of Simple Gas Foil Thrust Bearings in Air

    Bruckner, Robert J.

    2012-01-01

    Foil bearings are self-acting hydrodynamics devices used to support high speed rotating machinery. The advantages that they offer to process fluid lubricated machines include: high rotational speed capability, no auxiliary lubrication system, non-contacting high speed operation, and improved damping as compared to rigid hydrodynamic bearings. NASA has had a sporadic research program in this technology for almost 6 decades. Advances in the technology and understanding of foil journal bearings have enabled several new commercial products in recent years. These products include oil-free turbochargers for both heavy trucks and automobiles, high speed electric motors, microturbines for distributed power generation, and turbojet engines. However, the foil thrust bearing has not received a complimentary level of research and therefore has become the weak link of oil-free turbomachinery. In an effort to both provide machine designers with basic performance parameters and to elucidate the underlying physics of foil thrust bearings, NASA Glenn Research Center has completed an effort to experimentally measure the performance of simple gas foil thrust bearing in air. The database includes simple bump foil supported thrust bearings with full geometry and manufacturing techniques available to the user. Test conditions consist of air at ambient pressure and temperatures up to 500 C and rotational speeds to 55,000 rpm. A complete set of axial load, frictional torque, and rotational speed is presented for two different compliant sub-structures and inter-pad gaps. Data obtained from commercially available foil thrust bearings both with and without active cooling is presented for comparison. A significant observation made possible by this data set is the speed-load capacity characteristic of foil thrust bearings. Whereas for the foil journal bearing the load capacity increases linearly with rotational speed, the foil thrust bearing operates in the hydrodynamic high speed limit. In

  5. High Performance Methane Thrust Chamber (HPMTC) Project

    National Aeronautics and Space Administration — ORBITEC proposes to develop a High-Performance Methane Thrust Chamber (HPMRE) to meet the demands of advanced chemical propulsion systems for deep-space mission...

  6. An approach to evaluate capacitance, capacitive reactance and resistance of pivoted pads of a thrust bearing

    Prashad, Har

    1992-07-01

    A theoretical approach is developed for determining the capacitance and active resistance between the interacting surfaces of pivoted pads and thrust collar, under different conditions of operation. It is shown that resistance and capacitive reactance of a thrust bearing decrease with the number of pads times the values of these parameters for an individual pad, and that capacitance increases with the number of pads times the capacitance of an individual pad. The analysis presented has a potential to diagnose the behavior of pivoted pad thrust bearings with the angle of tilt and the ratio of film thickness at the leading to trailing edge, by determining the variation of capacitance, resistance, and capacitive reactance.

  7. High Thrust-to-Power Annular Engine Technology

    Patterson, Michael J.; Thomas, Robert E.; Crofton, Mark W.; Young, Jason A.; Foster, John E.

    2015-01-01

    Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground/in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

  8. Engineering research, development and technology. Thrust area report, FY93

    1994-05-01

    The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the technical staff, tools, and facilities needed to support current and future LLNL programs. The efforts are guided by a dual-benefit research and development strategy that supports Department of Energy missions, such as national security through nuclear deterrence and economic competitiveness through partnerships with U.S. industry. This annual report, organized by thrust area, describes the activities for the fiscal year 1993. The report provides timely summaries of objectives, methods, and results from nine thrust areas for this fiscal year: Computational Electronics and Electromagnetics; Computational Mechanics; Diagnostics and Microelectronics; Fabrication Technology; Materials Science and Engineering; Power Conversion Technologies; Nondestructive Evaluation; Remote Sensing, Imaging, and Signal Engineering; and Emerging Technologies. Separate abstracts were prepared for 47 papers in this report.

  9. A thrust balance for low power hollow cathode thrusters

    A hanging thrust balance has been designed, manufactured and tested at the University of Southampton. The current design allows for direct steady thrust measurements ranging from 0.1 to 3 mN but this can be easily extended to measure thrust in a different range. Moreover the chosen balance design and the thrust measurement procedure allow for the cancellation of thermal drifts. The thrust balance was tested with a T6 hollow cathode thruster providing measurements with an uncertainty of about 9.7%. The thrust data were compared to those obtained with another direct thrust balance and they are in quantitative agreement—the maximum difference being only 6%. (paper)

  10. Modelling of laser-based thrust generation for space debris removal

    Wilken, Jascha

    2015-01-01

    A possible method for the active removal of space debris is the irradiation of the debris with a pulsed laser system. With sufficient power the surface layer of the debris object is ablated and yields thrust, which will ideally lower the perigee of the debris object. The direction of the thrust is independent of the direction from which the debris object is irradiated, it is normal to the local surface. This thesis investigates the effects caused by complex shapes and varying orientation o...

  11. Axisymmetric thrust-vectoring nozzle performance prediction

    Throat-hinged geometrically variable converging-diverging thrust-vectoring nozzles directly affect the jet flow geometry and rotation angle at the nozzle exit as a function of the nozzle geometry, the nozzle pressure ratio and flight velocity. The consideration of nozzle divergence in the effective-geometric nozzle relation is theoretically considered here for the first time. In this study, an explicit calculation procedure is presented as a function of nozzle geometry at constant nozzle pressure ratio, zero velocity and altitude, and compared with experimental results in a civil thrust-vectoring scenario. This procedure may be used in dynamic thrust-vectoring nozzle design performance predictions or analysis for civil and military nozzles as well as in the definition of initial jet flow conditions in future numerical VSTOL/TV jet performance studies

  12. Evaluation of subcooled water thrust forces

    Subcooled water thrust forces for use in pipe rupture analyses have been normalized with respect to an enthalpy normalization factor. This normalization is based on comparisons with thrust forces calculated using the Henry-Fauske model, and the answers are within +-3 percent in the range 300 to 2400 psia (21.1 to 168.7 kg/cm2). The numerical evaluation makes it unnecessary for the user to rely on figures for the particular conditions desired or to program the Henry-Fauske method

  13. ICTAS announces thrust on nano-biomaterials

    Nystrom, Lynn A.

    2007-01-01

    Four innovative interdisciplinary programs connecting nanotechnology and health care are receiving initial seed funding from Virginia Tech's Institute for Critical Technology and Applied Science (ICTAS). The four areas will come under one of the designated primary research thrusts within ICTAS, "Nano-Biomaterials for the Delivery of Therapeutic and Diagnostic Agents."

  14. Variation in Magnitude of Differential Stress Across an Exhumed Continental-scale Thrust Zone

    Lusk, A. D.; Platt, J. P.

    2015-12-01

    The Moine Thrust Zone (MTZ), located in NW Scotland, formed as a result of the closing of the Iapetus Ocean and docking of various terranes and arcs (Scandian Phase of the Caledonian Orogeny, ca. 445-420 Ma). The MTZ as defined here comprises three major foreland-propagating thrust faults, the latest of which is the Moine Thrust itself, which emplaced Proterozoic Moine Supergroup psammites westward onto Cambro-Ordovician shelf sequence rocks and Lewisian basement gneiss. Presently, the north-south striking Moine Thrust Zone is exposed for more than 200 km along strike, and Scandian deformation can be traced up to 40 km eastward from the Moine Thrust towards the hinterland. The thrust system is thought to have been exhumed while still active, resulting in the exposure of deep structural levels of the MTZ. As part of an ongoing project to study how the stress, rheology, and width of continental-scale faults vary with depth, we use the piezometer based on the grainsize of dynamically recrystallized quartz to determine the variation in magnitude of differential stress across the MTZ. We present a transect from the head of Loch Eriboll in the footwall, eastward to the base of Ben Hope in the hangingwall. Grainsize generally decreases westward and structurally downward to the Moine Thrust, where ultramylonites have grainsizes on the order of 10 μm. Higher stresses towards the foreland likely reflect lower temperatures of deformation in rocks that before thrusting were at higher structural levels, and may have triggered a switch to grainsize sensitive creep, thus resulting in localization of strain and narrowing of shear zone width.

  15. Low-thrust transfer to Backflip orbits

    Pergola, P.

    2010-11-01

    The aim of the work is to design a low-thrust transfer from a Low Earth Orbit to a "useful" periodic orbit in the Earth-Moon Circular Restricted Three Body Model (CR3BP). A useful periodic orbit is here intended as one that moves both in the Earth-Moon plane and out of this plane without any requirements of propellant mass. This is achieved by exploiting a particular class of periodic orbits named Backflip orbits, enabled by the CR3BP. The unique characteristics of this class of periodic solutions allow the design of an almost planar transfer from a geocentric orbit and the use of the Backflip intrinsic characteristics to explore the geospace out of the Earth-Moon plane. The main advantage of this approach is that periodic plane changes can be obtained by performing an almost planar transfer. In order to save propellant mass, so as to increase the scientific payload of the mission, a low-powered transfer is considered. This foresees a thrusting phase to gain energy from a departing circular geocentric orbit and a second thrusting phase to match the state of the target Backflip orbit, separated by an intermediate ballistic phase. This results in a combined application of a low-thrust manoeuvre and of a periodical solution in the CR3BP to realize a new class of missions to explore the Earth-Moon neighbourhoods in a quite inexpensive way. In addition, a low-thrust transit between two different Backflip orbits is analyzed and considered as a possible extension of the proposed mission. Thus, also a Backflip-to-Backflip transfer is addressed where a low-powered probe is able to experience periodic excursions above and below the Earth-Moon plane only performing almost planar and very short transfers.

  16. Precise Thrust Actuation by a Micro RF Ion Engine Project

    National Aeronautics and Space Administration — Busek proposes to develop a radio-frequency discharge, gridded micro ion engine that produces 5N level of thrust precisely adjustable over a wide dynamic thrust...

  17. Quaternary deformation associated with the Tripoli-Roum Thrust, and the rise of the lebanese coast.

    Elias, A.; Tapponnier, P.; Jacques, E.; Daëron, M.; Klinger, Y.; Sursock, A.

    2003-04-01

    The Tripoli-Roum Thrust, which is part of the Levant Fault zone, appears to take up most of the shortening perpendicular to the Yammuneh Fault, thus producing the rise of Mount Lebanon since the late Neogene. In northern Lebanon, there is clear field evidence of active and recent folding and faulting along this thrust system. Three principal faults, oriented ~NNE-SSW, cut through the recent topography north of Tripoli. These oblique right-lateral strike-slip thrust ramps deform Neogene (Vindobonian to Astian) and Quaternary sedimentary and volcanic beds. The northernmost ramp is responsible for the growth of the young, asymmetric, Borj-el-Arab anticline, which folds Quaternary beachrocks and conglomerates, and reaches the Mediterranean coastline near Aabdé. This feature (thrust and ramp-anticline) continues offshore Tripoli, north of the Palmier and Rankine islands, and is probably responsible for the asymmetric uplift of shorelines and marine-cut terraces topping the islands. Active reverse faulting along the Tripoli-Roum thrust at sea appears to be also responsible for the rise of the many paleo-seacliffs and marine terraces found up to 500m asl along the Lebanese coast between Aabdé in the North and Saida in the South. Near Tabarja, and in the islands offshore Tripoli, we interpret the lowest uplifted marine terraces and double shoreline "trottoirs" identified and mapped by P. Sanlaville, to result from recurrent coseismic uplift during two or three seismic events on the offshore thrust. The last of these events was probably that which destroyed Beyrouth in 551A.D. Shell datings of the uplifted trottoirs yield 0,5 to 0,7 mm/yr as a first estimate of the uplift rate, relative to sea level, of the hanging wall of the Tripoli-Roum thrust ramp.

  18. Electromechanical actuation for thrust vector control applications

    Roth, Mary Ellen

    At present, actuation systems for the Thrust Vector Control (TVC) for launch vehicles are hydraulic systems. The Advanced Launch System (ALS), a joint initiative between NASA and the Air Force, is a launch vehicle that is designed to be cost effective, highly reliable and operationally efficient with a goal of reducing the cost per pound to orbit. As part of this initiative, an electromechanical actuation system is being developed as an attractive alternative to the hydraulic systems used today. NASA-Lewis is developing and demonstrating an Induction Motor Controller Actuation System with a 40 hp peak rating. The controller will integrate 20 kHz resonant link Power Management and Distribution (PMAD) technology and Pulse Population Modulation (PPM) techniques to implement Field Oriented Vector Control (FOVC) of a new advanced induction motor. Through PPM, multiphase variable frequency, variable voltage waveforms can be synthesized from the 20 kHz source. FOVC shows that varying both the voltage and frequency and their ratio (V/F), permits independent control of both torque and speed while operating at maximum efficiency at any point on the torque-speed curve. The driver and the FOVC will be microprocessor controlled. For increased system reliability, a Built-in Test (BITE) capability will be included. This involves introducing testability into the design of a system such that testing is calibrated and exercised during the design, manufacturing, maintenance and prelaunch activities. An actuator will be integrated with the motor controller for performance testing of the EMA TVC system. The design and fabrication of the motor controller is being done by General Dynamics Space Systems Division. The University of Wisconsin-Madison will assist in the design of the advanced induction motor and in the implementation of the FOVC theory. A 75 hp electronically controlled dynamometer will be used to test the motor controller in all four quadrants of operation using flight type

  19. Evolution of the Puente Hills Thrust Fault

    Bergen, K. J.; Shaw, J. H.; Dolan, J. F.

    2013-12-01

    This study aims to assess the evolution of the blind Puente Hills thrust fault system (PHT) by determining its age of initiation, lateral propagation history, and changes in slip rate over time. The PHT presents one of the largest seismic hazards in the United States, given its location beneath downtown Los Angeles. The PHT is comprised of three fault segments: the Los Angeles (LA), Santa Fe Springs (SFS), and Coyote Hills (CH). The LA and SFS segments are characterized by growth stratigraphy where folds formed by uplift on the fault segments have been continually buried by sediment from the Los Angeles and San Gabriel rivers. The CH segment has developed topography and is characterized by onlapping growth stratigraphy. This depositional setting gives us the unique opportunity to measure uplift on the LA and SFS fault segments, and minimum uplift on the CH fault segment, as the difference in sediment thicknesses across the buried folds. We utilize depth converted oil industry seismic reflection data to image the fold geometries. Identifying time-correlative stratigraphic markers for slip rate determination in the basin has been a problem for researchers in the past, however, as the faunal assemblages observed in wells are time-transgressive by nature. To overcome this, we utilize the sequence stratigraphic model and well picks of Ponti et al. (2007) as a basis for mapping time-correlative sequence boundaries throughout our industry seismic reflection data from the present to the Pleistocene. From the Pleistocene to Miocene we identify additional sequence boundaries in our seismic reflection data from imaged sequence geometries and by correlating industry well formation tops. The sequence and formation top picks are then used to build 3-dimensional surfaces in the modeling program Gocad. From these surfaces we measure the change in thicknesses across the folds to obtain uplift rates between each sequence boundary. Our results show three distinct phases of

  20. NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS

    NA

    2005-07-27

    This booklet contains project descriptions of work performed by the Department of Energy (DOE), Office of Civilian Radioactive Waste Management (OCRWM), Office of Science and Technology and International's (OST&I) Natural Barriers Targeted Thrust during Fiscal Year (FY) 2004. The Natural Barriers Targeted Thrust is part of OST&I's Science and Technology Program which supports the OCRWM mission to manage and dispose of high-level radioactive waste and spent nuclear fuel in a manner that protects health, safety, and the environment; enhances national and energy security; and merits public confidence. In general, the projects described will continue beyond FY 2004 assuming that the technical work remains relevant to the proposed Yucca Mountain Repository and sufficient funding is made available to the Science and Technology Program.

  1. MATERIALS PERFORMANCE TARGETED THRUST FY 2004 PROJECTS

    The Yucca Mountain site was recommended by the President to be a geological repository for commercial spent nuclear fuel and high-level radioactive waste. The multi-barrier approach was adopted for assessing and predicting system behavior, including both natural barriers and engineered barriers. A major component of the long-term strategy for safe disposal of nuclear waste is first to completely isolate the radionuclides in waste packages for long times and then to greatly retard the egress and transport of radionuclides from penetrated packages. The goal of the Materials Performance Targeted Thrust program is to further enhance the understanding of the role of engineered barriers in waste isolation. In addition, the Thrust will explore technical enhancements and seek to offer improvements in materials costs and reliability

  2. Thrust vector control using electric actuation

    Bechtel, Robert T.; Hall, David K.

    1995-01-01

    Presently, gimbaling of launch vehicle engines for thrust vector control is generally accomplished using a hydraulic system. In the case of the space shuttle solid rocket boosters and main engines, these systems are powered by hydrazine auxiliary power units. Use of electromechanical actuators would provide significant advantages in cost and maintenance. However, present energy source technologies such as batteries are heavy to the point of causing significant weight penalties. Utilizing capacitor technology developed by the Auburn University Space Power Institute in collaboration with the Auburn CCDS, Marshall Space Flight Center (MSFC) and Auburn are developing EMA system components with emphasis on high discharge rate energy sources compatible with space shuttle type thrust vector control requirements. Testing has been done at MSFC as part of EMA system tests with loads up to 66000 newtons for pulse times of several seconds. Results show such an approach to be feasible providing a potential for reduced weight and operations costs for new launch vehicles.

  3. Static Thrust Analysis of the Lifting Airscrew

    Knight, Montgomery; Hefner, Ralph A

    1937-01-01

    This report presents the results of a combined theoretical and experimental investigation conducted at the Georgia School of Technology on the static thrust of the lifting air screw of the type used in modern autogiros and helicopters. The theoretical part of this study is based on Glauert's analysis but certain modifications are made that further clarify and simplify the problem. Of these changes the elimination of the solidity as an independent parameter is the most important. The experimental data were obtained from tests on four rotor models of two, four, and five blades and, in general, agree quite well with the theoretical calculations. The theory indicates a method of evaluating scale effects on lifting air screws, and these corrections have been applied to the model results to derive general full-scale static thrust, torque, and figure-of-merit curves for constant-chord, constant-incidence rotors. Convenient charts are included that enable hovering flight performance to be calculated rapidly.

  4. Electromechanical actuator for thrust vector control

    Zubkow, Zygmunt

    Attention is given to the development and testing of electromechanical actuator (EMA) systems for use in first- and second-stage thrust vector control of rocket engines. An overview of the test program is also presented. Designs for both first- and second-stage actuators employ redundant dc brushless, three-phase rare-earth permanent magnet motors. The first-stage actuator is about 28 hp per motor and uses a roller screw. Second-stage thrust vector control is implemented with a much smaller actuator of about 1 hp per motor. This actuator uses a gear drive with a recycling ball screw mechanism. An operational EMA is presented. This 6.5-in. actuator is capable of a stall force of 1350 pounds per motor and a frequency response of about 5 HZ.

  5. Evolutionary Computing for Low-thrust Navigation

    Lee, Seungwon; Fink, Wolfgang; vonAllmed, Paul; Petropoulos, Anastassios E.; Russell, Ryan P.; Terrile, Richard J.

    2005-01-01

    The development of new mission concepts requires efficient methodologies to analyze, design and simulate the concepts before implementation. New mission concepts are increasingly considering the use of ion thrusters for fuel-efficient navigation in deep space. This paper presents parallel, evolutionary computing methods to design trajectories of spacecraft propelled by ion thrusters and to assess the trade-off between delivered payload mass and required flight time. The developed methods utilize a distributed computing environment in order to speed up computation, and use evolutionary algorithms to find globally Pareto-optimal solutions. The methods are coupled with two main traditional trajectory design approaches, which are called direct and indirect. In the direct approach, thrust control is discretized in either arc time or arc length, and the resulting discrete thrust vectors are optimized. In the indirect approach, a thrust control problem is transformed into a costate control problem, and the initial values of the costate vector are optimized. The developed methods are applied to two problems: 1) an orbit transfer around the Earth and 2) a transfer between two distance retrograde orbits around Europa, the closest to Jupiter of the icy Galilean moons. The optimal solutions found with the present methods are comparable to other state-of-the-art trajectory optimizers and to analytical approximations for optimal transfers, while the required computational time is several orders of magnitude shorter than other optimizers thanks to an intelligent design of control vector discretization, advanced algorithmic parameterization, and parallel computing.

  6. Engineering Research and Development and Technology thrust area report FY92

    Langland, R.T.; Minichino, C. [eds.

    1993-03-01

    The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the technical staff and the technology needed to support current and future LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) to identify key technologies and (2) to conduct high-quality work to enhance our capabilities in these key technologies. To help focus our efforts, we identify technology thrust areas and select technical leaders for each area. The thrust areas are integrated engineering activities and, rather than being based on individual disciplines, they are staffed by personnel from Electronics Engineering, Mechanical Engineering, and other LLNL organizations, as appropriate. The thrust area leaders are expected to establish strong links to LLNL program leaders and to industry; to use outside and inside experts to review the quality and direction of the work; to use university contacts to supplement and complement their efforts; and to be certain that we are not duplicating the work of others. This annual report, organized by thrust area, describes activities conducted within the Program for the fiscal year 1992. Its intent is to provide timely summaries of objectives, theories, methods, and results. The nine thrust areas for this fiscal year are: Computational Electronics and Electromagnetics; Computational Mechanics; Diagnostics and Microelectronics; Emerging Technologies; Fabrication Technology; Materials Science and Engineering; Microwave and Pulsed Power; Nondestructive Evaluation; and Remote Sensing and Imaging, and Signal Engineering.

  7. Engineering Research and Development and Technology thrust area report FY92

    The mission of the Engineering Research, Development, and Technology Program at Lawrence Livermore National Laboratory (LLNL) is to develop the technical staff and the technology needed to support current and future LLNL programs. To accomplish this mission, the Engineering Research, Development, and Technology Program has two important goals: (1) to identify key technologies and (2) to conduct high-quality work to enhance our capabilities in these key technologies. To help focus our efforts, we identify technology thrust areas and select technical leaders for each area. The thrust areas are integrated engineering activities and, rather than being based on individual disciplines, they are staffed by personnel from Electronics Engineering, Mechanical Engineering, and other LLNL organizations, as appropriate. The thrust area leaders are expected to establish strong links to LLNL program leaders and to industry; to use outside and inside experts to review the quality and direction of the work; to use university contacts to supplement and complement their efforts; and to be certain that we are not duplicating the work of others. This annual report, organized by thrust area, describes activities conducted within the Program for the fiscal year 1992. Its intent is to provide timely summaries of objectives, theories, methods, and results. The nine thrust areas for this fiscal year are: Computational Electronics and Electromagnetics; Computational Mechanics; Diagnostics and Microelectronics; Emerging Technologies; Fabrication Technology; Materials Science and Engineering; Microwave and Pulsed Power; Nondestructive Evaluation; and Remote Sensing and Imaging, and Signal Engineering

  8. Thrust evaluation of magneto plasma sail that obtains an electromagnetic thrust from the solar wind

    Magneto Plasma Sail (MPS) is a propulsion system used in space, which generates its force by the interaction between the solar wind and an inflated magnetic field via a plasma injection. The quantitative evaluation of the thrust increment generated by injecting a plasma jet with a βin less than unity was conducted by three-dimensional hybrid particle-in-cell (PIC) simulations in an ion inertia scale. The injected plasma βin is 0.02 and the ratio of Larmor radius of injected ion to the representative length of the magnetic field is 0.5 at the injection point. In this situation, the obtained thrust of the MPS is 1.6 mN compared with the 0.2 mN of the thrust obtained by the pure magnetic sail since the induced current region on magnetosphere expanded by the magnetic inflation. (author)

  9. Optimum Staging with Varying Thrust Attitude Angle

    T. N. Srivastava

    1966-07-01

    Full Text Available Optimum staging programme for step rockets of arbitrary number of stages having different specific impulses and mass fractions with stages is derived, the optimization criterion being minimum take-off weight for a desired burntout velocity at an assigned altitude. Variation of thrust attitude angle from stage to stage and effects of gravity factor are taken into account. Analysis is performed for a degenerate problem obtained by relaxing the altitude constraint and it has been shown that problems of Weisbord, Subotowicz, Hall & Zambelli and Malina & Summerfield are the particular cases of the degenerate problem.

  10. Entrainment and mixing in thrust augmenting ejectors

    Bernal, L.; Sarohia, V.

    1983-01-01

    An experimental investigation of two-dimensional thrust augmenting ejector flows has been conducted. Measurements of the shroud surface pressure distribution, mean velocity, turbulent intensities and Reynolds stresses were made in two shroud geometries at various primary nozzle pressure ratios. The effects of shroud geometry and primary nozzle pressure ratio on the shroud surface pressure distribution, mean flow field and turbulent field were determined. From these measurements the evolution of mixing within the shroud of the primary flow and entrained fluid was obtained. The relationship between the mean flow field, the turbulent field and the shroud surface pressure distribution is discussed.

  11. Growth of the Zagros Fold-Thrust Belt and Foreland Basin, Northern Iraq, Kurdistan

    Koshnaw, Renas; Horton, Brian; Stockli, Daniel; Barber, Douglas; Ghalib, Hafidh; Dara, Rebwar

    2016-04-01

    The Zagros orogenic belt in the Middle Eastern segment of the Alpine-Himalayan system is among the youngest seismically active continental collision zones on Earth. However, due to diachronous and incremental collision, the precise ages and kinematics of shortening and deposition remain poorly understood. The Kurdistan region of the Zagros fold-thrust belt and foreland basin contains well-preserved Neogene wedge-top and foredeep deposits that include clastic nonmarine fill of the Upper Fars, Lower Bakhtiari, and Upper Bakhtiari Formations. These deposits record significant information about orogenic growth, fold-thrust dynamics, and advance of the deformation front. Thermochronologic and geochronologic data from thrust sheets and stratigraphic archives combined with local earthquake data provide a unique opportunity to address the linkages between surface and subsurface geologic relationships. This research seeks to constrain the timing and geometry of exhumation and deformation by addressing two key questions: (1) Did the northwestern Zagros fold-thrust belt evolve from initial thin-skinned shortening to later thick-skinned deformation or vice-versa? (2) Did the fold-thrust belt advance steadily under critical/supercritical wedge conditions involving in-sequence thrusting or propagate intermittently under subcritical conditions with out-of-sequence deformation? From north to south, apatite (U-Th)/He ages from the Main Zagros Thrust, the Mountain Front Flexure (MFF), and additional frontal thrusts suggest rapid exhumation by ~10 Ma, ~5 Ma, and ~8 Ma respectively. Field observations and seismic sections indicate progressive tilting and development of growth strata within the Lower Bakhtiari Formation adjacent to the frontal thrusts and within the Upper Bakhtiari Formation near the MFF. In the Kurdistan region of Iraq, a regional balanced cross section constrained by new thermochronometric results, proprietary seismic reflection profiles, and earthquake hypocenters

  12. Local Thrust Faulting Along the Southern Hayward Fault in Fremont, California

    Johnson, P. L.; Sayre, T. M.

    2015-12-01

    The southern Hayward fault is an active, northwest-striking, right lateral strike slip fault within the densely populated eastern San Francisco Bay area. Recent subsurface investigation along the southern Hayward fault has revealed unexpectedly complex deformation between subparallel fault traces. In the city of Fremont, the southern Hayward fault crosses Mission Boulevard (MB) as three parallel to subparallel traces, the eastern, central, and western traces. Recent exploratory trenches excavated near MB by another consultant and logged by the authors revealed that the western and central traces of the Hayward fault are nearly parallel with limited secondary deformation between them. However, along strike farther to the northwest, abundant secondary deformation in the form of multiple northeast-dipping thrust faults was encountered in the exploratory trenches. The thrust faults locally place Plio-Pleistocene Irvington Gravels Formation over slope wash deposits and Bk horizon soils, implying late Quaternary activity. Field reconnaissance and review of historical aerial photographs that pre-date urbanization revealed no geomorphic evidence of landslides in the vicinity of the identified thrust faults, and subsurface investigation did not identify evidence of a landslide graben on the upper slope. Slope inclinations in this area are mostly low to moderate (6° to 12°) with few steeper inclinations (up to 20°). Thus, these compressional structures appear to be unrelated to landsliding. Our working hypothesis for the origin of the thrust faults northwest of MB involves compression related to a small left step along the central trace. This left step corresponds closely to the location of the observed thrust faults. The resulting compression is manifest as a series of thrust faults that do not appear to continue north or south of the step over region.

  13. Reconciling Himalayan midcrustal discontinuities: The Main Central thrust system

    Larson, Kyle P.; Ambrose, Tyler K.; Webb, A. Alexander G.; Cottle, John M.; Shrestha, Sudip

    2015-11-01

    The occurrence of thrust-sense tectonometamorphic discontinuities within the exhumed Himalayan metamorphic core can be explained as part of the Main Central thrust system. This imbricate thrust structure, which significantly thickened the orogenic midcrustal core, comprises a series of thrust-sense faults that all merge into a single detachment. The existence of these various structures, and their potential for complex overprinting along the main detachment, may help explain the contention surrounding the definition, mapping, and interpretation of the Main Central thrust. The unique evolution of specific segments of the Main Central thrust system along the orogen is interpreted to be a reflection of the inherent basement structure and ramp position, and structural level of exposure of the mid-crust. This helps explain the variation in the timing and structural position of tectonometamorphic discontinuities along the length of the mountain belt.

  14. Neandertal humeri may reflect adaptation to scraping tasks, but not spear thrusting.

    Colin N Shaw

    Full Text Available Unique compared with recent and prehistoric Homo sapiens, Neandertal humeri are characterised by a pronounced right-dominant bilateral strength asymmetry and an anteroposteriorly strengthened diaphyseal shape. Remodeling in response to asymmetric forces imposed during regular underhanded spear thrusting is the most influential explanatory hypothesis. The core tenet of the "Spear Thrusting Hypothesis", that underhand thrusting requires greater muscle activity on the right side of the body compared to the left, remains untested. It is unclear whether alternative subsistence behaviours, such as hide processing, might better explain this morphology. To test this, electromyography was used to measure muscle activity at the primary movers of the humerus (pectoralis major (PM, anterior (AD and posterior deltoid (PD during three distinct spear-thrusting tasks and four separate scraping tasks. Contrary to predictions, maximum muscle activity (MAX and total muscle activity (TOT were significantly higher (all values, p<.05 at the left (non-dominant AD, PD and PM compared to the right side of the body during spear thrusting tasks. Thus, the muscle activity required during underhanded spearing tasks does not lend itself to explaining the pronounced right dominant strength asymmetry found in Neandertal humeri. In contrast, during the performance of all three unimanual scraping tasks, right side MAX and TOT were significantly greater at the AD (all values, p<.01 and PM (all values, p<.02 compared to the left. The consistency of the results provides evidence that scraping activities, such as hide preparation, may be a key behaviour in determining the unusual pattern of Neandertal arm morphology. Overall, these results yield important insight into the Neandertal behavioural repertoire that aided survival throughout Pleistocene Eurasia.

  15. A Low Friction Thrust Bearing for Reciprocating Compressors

    Nagata, Shuhei; Kousokabe, Hirokatsu; Sekiyama, Nobuya; Ono, Toshiaki

    2012-01-01

    A thrust bearing with a micro texture on its sliding surface that produces hydrodynamic pressure was developed for use in reciprocating compressors. Evaluation using an elemental friction test showed that its friction loss was 20–60 % lower than that of the current design. Measurement of the efficiency of a compressor with the developed thrust bearing showed that the coefficient of performance was 1.4 % higher than that of a compressor with a conventional thrust bearing.

  16. Thrust loss on azimuthing thrusters due to Coanda effect

    Fjørtoft, Henrik

    2010-01-01

    The main objectives in this master's thesis is to investigate how the Coanda effect influences a thruster jet which further causes a thrust loss.The tendency of a thruster slipstream to be deflected towards a nearby surface, for most practical situations the hull of a vessel, is called the Coanda effect and is likely to produce a significant thrust loss under certain geometric conditions.The approach in this master's thesis is to perform an experiment measuring the direct thrust loss related ...

  17. Versatile and Extensible, Continuous-Thrust Trajectory Optimization Tool Project

    National Aeronautics and Space Administration — We propose to develop an innovative, versatile and extensible, continuous-thrust trajectory optimization tool for planetary mission design and optimization of...

  18. Unsteady thrust measurement techniques for pulse detonation engines

    Joshi, Dibesh Dhoj

    Thrust is a critical performance parameter and its correct determination is necessary to characterize an engine. Many conventional thrust measurement techniques prevail. However, further developments are required for correct measurement of thrust in the case of a pulse detonation engine (PDE), since the entire thrust generation process is intermittent. The significant effect of system dynamics in the form of inertial forces, stress wave propagation and reflections initiated in the structure due to detonations and pulse-to-pulse interaction in a fast operating PDE further complicate the thrust measurement process. These complications call for a further, detailed study of the unsteady thrust characteristics. A general approach was first developed to recover actual thrust from the measured thrust generated by the PDE. The developed approach consisted of two steps. The first step incorporated a deconvolution procedure using a pre-established system transfer function and measured input to reconstruct the output yielding the deconvolved thrust. The second step accounted for inertial forces through an acceleration compensation procedure. These two steps allowed the actual thrust to be determined. A small scale PDE operating at 10 and 20 Hz with varied filling fractions and mixture equivalence ratios was used for the experimental application of the general approach. The analytical study of gas dynamics in the PDE while in operation and the measured pressure histories at the exit of the engine allowed the generated thrust during a cycle to be determined semi-empirically. The thrust values determined semi-empirically were compared against the experimental results. A dynamical model of the PDE was created for the study of the unsteady thrust characteristics using finite element analysis. The results from finite element analysis were compared against semi-empirical and experimental results. In addition, finite element analysis also facilitated to numerically determine the

  19. Structural Discordance Between Neogene Detachments and Frontal Sevier Thrusts, Central Mormon Mountains, Southern Nevada

    Wernicke, Brian; Walker, J. Douglas; Beaufait, Mark S.

    1985-02-01

    Detailed geologic mapping in the Mormon Mountains of southern Nevada provides significant insight into processes of extensional tectonics developed within older compressional orogens. A newly discovered, WSW-directed low-angle normal fault, the Mormon Peak detachment, juxtaposes the highest levels of the frontal most part of the east-vergent, Mesozoic Sevier thrust belt with autochthonous crystalline basement. Palinspastic analysis suggests that the detachment initially dipped 20-25° to the west and cut discordantly across thrust faults. Nearly complete lateral removal of the hanging wall from the area has exposed a 5 km thick longitudinal cross-section through the thrust belt in the footwall, while highly attenuated remnants of the hanging wall (nowhere more than a few hundred meters thick) structurally veneer the range. The present arched configuration of the detachment resulted in part from progressive "domino-style" rotation of a few degrees while it was active, but is largely due to rotation on younger, structurally lower, basement-penetrating normal faults that initiated at high-angle. The geometry and kinematics of normal faulting in the Mormon Mountains suggest that pre-existing thrust planes are not required for the initiation of low-angle normal faults, and even where closely overlapped by extensional tectonism, need not function as a primary control of detachment geometry. Caution must thus be exercised in interpreting low-angle normal faults of uncertain tectonic heritage such as those seen in the COCORP west-central Utah and BIRP's MOIST deep-reflection profiles. Although thrust fault reactivation has reasonably been shown to be the origin of a very few low-angle normal faults, our results indicate that it may not be as fundamental a component of orogenic architecture as it is now widely perceived to be. We conclude that while in many instances thrust fault reactivation may be both a plausible and attractive hypothesis, it may never be assumed.

  20. Secondary production of massive quarks in thrust

    We present a factorization framework that takes into account the production of heavy quarks through gluon splitting in the thrust distribution for e+e− → hadrons. The explicit factorization theorems and some numerical results are displayed in the dijet region where the kinematic scales are widely separated, which can be extended systematically to the whole spectrum. We account for the necessary two-loop matrix elements, threshold corrections, and include resummation up to N3LL order. We include nonperturbative power corrections through a field theoretical shape function, and remove the O(ΛQCD) renormalon in the partonic soft function by appropriate mass-dependent subtractions. Our results hold for any value of the quark mass, from an infinitesimally small (merging to the known massless result) to an infinitely large one (achieving the decoupling limit). This is the first example of an application of a variable flavor number scheme to final state jets

  1. Small centrifugal pumps for low thrust rockets

    Gulbrandsen, N. C.; Furst, R. B.; Burgess, R. M.; Scheer, D. D.

    1985-01-01

    This paper presents the results of a combined analytical and experimental investigation of low specific speed pumps for potential use as components of propellant feed systems for low thrust rocket engines. Shrouded impellers and open face impellers were tested in volute type and vaned diffuser type pumps. Full- and partial-emission diffusers and full- and partial-admission impellers were tested. Axial and radial loads, head and efficiency versus flow, and cavitation tests were conducted. Predicted performance of two pumps are compared when pumping water and liquid hydrogen. Detailed pressure loss and parasitic power values are presented for two pump configurations. Partial-emission diffusers were found to permit use of larger impeller and diffuser passages with a minimal performance penalty. Normal manufacturing tolerances were found to result in substantial power requirement variation with only a small pressure rise change. Impeller wear ring leakage was found to reduce pump pressure rise to an increasing degree as the pump flowrate was decreased.

  2. Secondary production of massive quarks in thrust

    Hoang, André H.; Mateu, Vicent; Pietrulewicz, Piotr

    2016-01-01

    We present a factorization framework that takes into account the production of heavy quarks through gluon splitting in the thrust distribution for e+e- → hadrons. The explicit factorization theorems and some numerical results are displayed in the dijet region where the kinematic scales are widely separated, which can be extended systematically to the whole spectrum. We account for the necessary two-loop matrix elements, threshold corrections, and include resummation up to N3LL order. We include nonperturbative power corrections through a field theoretical shape function, and remove the O(ΛQCD) renormalon in the partonic soft function by appropriate mass-dependent subtractions. Our results hold for any value of the quark mass, from an infinitesimally small (merging to the known massless result) to an infinitely large one (achieving the decoupling limit). This is the first example of an application of a variable flavor number scheme to final state jets.

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

    Forde, Scott; Bulman, Mel; Neill, Todd

    2006-07-01

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

  4. Electronics Engineering Department Thrust Area report FY'84

    This report describes the work of the Electronics Engineering Department Thrust Areas for FY'84: diagnostics and microelectronic engineering; signal and control engineering; microwave and pulsed power engineering; computer-aided engineering; engineering modeling and simulation; and systems engineering. For each Thrust Area, an overview and a description of the goals and achievements of each project is provided

  5. A magnetic coupling thrust stand for microthrust measurements

    Wright, W. P.; Ferrer, P.

    2016-01-01

    A direct thrust measurement system that is based on a horizontal lever and utilizes a novel magnetic coupling mechanism to measure thrust has been developed. The system is capable of measuring thrusts as low as 10’s of μN. While zero drift is observed in the balance, tests have shown that they do not have an appreciable effect on thrust measurements. The thrust stand’s sensitivity can be adjusted by shifting the position of the coupling magnet inside the stand’s thrust support member, which allows flexibility for testing both higher and lower powered thrusters. The thrust stand has been modeled theoretically and the predicted results from the model are compared with experimentally measured data. The system was tested using a simple cold gas thruster and provided credible results that can be compared with other systems studied in the literature. Advantages include that the thrust stand is very cheap and easy to construct and further, the calibration process takes no longer than half an hour, facilitating rapid turnaround times while still retaining accuracy. Repeatability tests have shown that the balance gives consistent results.

  6. Transient analysis of blowdown thrust force under PWR LOCA

    The analytical results of blowdown characteristics and thrust forces were compared with the experiments, which were performed as pipe whip and jet discharge tests under the PWR LOCA conditions. The blowdown thrust forces obtained by Navier-Stokes momentum equation about a single-phase, homogeneous and separated two-phase flow, assuming critical pressure at the exit if a critical flow condition was satisfied. The following results are obtained. (1) The node-junction method is useful for both the analyses of the blowdown thrust force and of the water hammer phenomena. (2) The Henry-Fauske model for subcooled critical flow is effective for the analysis of the maximum thrust force under the PWR LOCA conditions. The jet thrust parameter of the analysis and experiment is equal to 1.08. (3) The thrust parameter of saturated blowdown has the same one with the value under pressurized condition when the stagnant pressure is chosen as the saturated one. (4) The dominant terms of the blowdown thrust force in the momentum equation are the pressure and momentum terms except that the acceleration term has large contribution only just after the break. (5) The blowdown thrust force in the analysis greatly depends on the selection of the exit pressure. (author)

  7. Electronics Engineering Department Thrust Area report FY'84

    Minichino, C.; Phelps, P.L. (eds.)

    1984-01-01

    This report describes the work of the Electronics Engineering Department Thrust Areas for FY'84: diagnostics and microelectronic engineering; signal and control engineering; microwave and pulsed power engineering; computer-aided engineering; engineering modeling and simulation; and systems engineering. For each Thrust Area, an overview and a description of the goals and achievements of each project is provided.

  8. Momentum Management Tool for Low-Thrust Missions

    Swenka, Edward R.; Smith, Brett A.; Vanelli, Charles A.

    2010-01-01

    A momentum management tool was designed for the Dawn low-thrust interplanetary spacecraft en route to the asteroids Vesta and Ceres, in an effort to better understand the early creation of the solar system. Momentum must be managed to ensure the spacecraft has enough control authority to perform necessary turns and hold a fixed inertial attitude against external torques. Along with torques from solar pressure and gravity-gradients, ion-propulsion engines produce a torque about the thrust axis that must be countered by the four reaction wheel assemblies (RWA). MomProf is a ground operations tool built to address these concerns. The momentum management tool was developed during initial checkout and early cruise, and has been refined to accommodate a wide range of momentum-management issues. With every activity or sequence, wheel speeds and momentum state must be checked to avoid undesirable conditions and use of consumables. MomProf was developed to operate in the MATLAB environment. All data are loaded into MATLAB as a structure to provide consistent access to all inputs by individual functions within the tool. Used in its most basic application, the Dawn momentum tool uses the basic principle of angular momentum conservation, computing momentum in the body frame, and RWA wheel speeds, for all given orientations in the input file. MomProf was designed specifically to be able to handle the changing external torques and frequent de - saturations. Incorporating significant external torques adds complexity since there are various external torques that act under different operational modes.

  9. New Highly Dynamic Approach for Thrust Vector Control

    Hecht, M.; Ettl, J.; Grothe, D.; Hrbud, I.

    2015-09-01

    For a new launcher system a thrust vector control system is needed. This launch vehicle system consists of two rockets which are namely the VS-50 (two-stage suborbital vehicle) and the VLM-1 (three-stage microsatellite launch vehicle). VLM-1 and VS-50 are developed in a cooperation between the German Aerospace Center (DLR) and the Brazilian Aeronautics and Space Institute (IAE). To keep these two rockets on its trajectory during flight a highly dynamic thrust vector control system is required. For the purpose of developing such a highly dynamic thrust vector control system a master thesis was written by the author. The development includes all mechanical constructions as well as control algorithms and electronics design. Moreover an optimization of control algorithms was made to increase the dynamic capabilities of the thrust vector control system. The composition of the right components plus the sophisticated control algorithm make the thrust vector control system highly dynamic.

  10. Smoother thrust on multi-polar type linear DC motor

    Wakiwaka, H.; Senoh, S.; Yajima, H; Yamada, H. [Shinshu Univ., Wakasato, Nagano (Japan). Faculty of Engineering; Oda, J. [Ohkura Electric Co., Ltd., Shirako, Wakou (Japan)

    1997-09-01

    A LDM has the merits of a high response and a direct linear motion. Therefore, a LDM is used widely in the fields of Factory Automation (FA). As compared with a mono-polar type Linear DC Motor (LDM), it is possible for a multi-polar type LDM to have a longer stroke and more thrust with thin shape. However, there are thrust ripple on multi-polar type one. In this paper, a design to prevent thrust ripple is discussed. In order to make a smoother thrust on multi-polar type LDM, the structure of the LDM is set as a 2-phase coil type. This paper clarifies that the thrust ripple of the LDM has the minimum value of 1.68%, the pole pitch of 15 mm, the coil width of 12 mm and the permanent magnet width of 10 mm.

  11. Reaction thrust of water jet for conical nozzles

    HUANG Guo-qin; YANG You-sheng; LI Xiao-hui; ZHU Yu-quan

    2009-01-01

    Clear knowledge on the reaction thrust of water jet is valuable for better design of water jet propulsion system.In this paper,theoretical,numerical and experimental studies were carried out to investigate the effects of the nozzle geometry as well as the inlet conditions on the reaction thrust of water jet.Comparison analyses reveal that the reaction thrust has a direct proportional relationship with the product of the inlet pressure,the square of flow rate and two-thirds power exponent of the input power.The results also indicate that the diameter of the cylinder column for the conical nozzle has great influence on the reaction thrust characteristics.In addition,the best values of the half cone angle and the cylinder column length exist to make the reaction thrust reach its maximum under the same inlet conditions.

  12. Thrust Measurements for a Pulse Detonation Engine Driven Ejector

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

    2005-01-01

    Results of an experimental effort on pulse detonation driven ejectors aimed at probing different aspects of PDE ejector processes, are presented and discussed. The PDE was operated using ethylene as the fuel and an equimolar oxygen/nitrogen mixture as the oxidizer at an equivalence ratio of one. The thrust measurements for the PDE alone are in excellent agreement with experimental and modeling results reported in the literature and serve as a Baseline for the ejector studies. These thrust measurements were then used as a basis for quantifying thrust augmentation for various PDE/ejector setups using constant diameter ejector tubes and various detonation tube/ejector tube overlap distances. The results show that for the geometries studied here, a maximum thrust augmentation of 24% is achieved. The thrust augmentation results are complemented by shadowgraph imaging of the flowfield in the ejector tube inlet area and high frequency pressure transducer measurements along the length of the ejector tube.

  13. Initial Thrust Measurements of Marshall's Ion-ioN Thruster

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

    2015-01-01

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

  14. Multiphysics Thrust Chamber Modeling for Nuclear Thermal Propulsion

    Wang, Ten-See; Cheng, Gary; Chen, Yen-Sen

    2006-01-01

    The objective of this effort is to develop an efficient and accurate thermo-fluid computational methodology to predict environments for a solid-core, nuclear thermal engine thrust chamber. The computational methodology is based on an unstructured-grid, pressure-based computational fluid dynamics formulation. A two-pronged approach is employed in this effort: A detailed thermo-fluid analysis on a multi-channel flow element for mid-section corrosion investigation; and a global modeling of the thrust chamber to understand the effect of heat transfer on thrust performance. Preliminary results on both aspects are presented.

  15. Thrust measurement method verification and analytical studies on a liquid-fueled pulse detonation engine

    Lu Jie

    2014-06-01

    Full Text Available In order to test the feasibility of a new thrust stand system based on impulse thrust measurement method, a liquid-fueled pulse detonation engine (PDE is designed and built. Thrust performance of the engine is obtained by direct thrust measurement with a force transducer and indirect thrust measurement with an eddy current displacement sensor (ECDS. These two sets of thrust data are compared with each other to verify the accuracy of the thrust performance. Then thrust data measured by the new thrust stand system are compared with the verified thrust data to test its feasibility. The results indicate that thrust data from the force transducer and ECDS system are consistent with each other within the range of measurement error. Though the thrust data from the impulse thrust measurement system is a litter lower than that from the force transducer due to the axial momentum losses of the detonation jet, the impulse thrust measurement method is valid when applied to measure the averaged thrust of PDE. Analytical models of PDE are also discussed in this paper. The analytical thrust performance is higher than the experimental data due to ignoring the losses during the deflagration to detonation transition process. Effect of equivalence ratio on the engine thrust performance is investigated by utilizing the modified analytical model. Thrust reaches maximum at the equivalence ratio of about 1.1.

  16. Rapid prototype fabrication processes for high-performance thrust cells

    Hunt, K.; Chwiedor, T.; Diab, J.; Williams, R.

    1994-01-01

    The Thrust Cell Technologies Program (Air Force Phillips Laboratory Contract No. F04611-92-C-0050) is currently being performed by Rocketdyne to demonstrate advanced materials and fabrication technologies which can be utilized to produce low-cost, high-performance thrust cells for launch and space transportation rocket engines. Under Phase 2 of the Thrust Cell Technologies Program (TCTP), rapid prototyping and investment casting techniques are being employed to fabricate a 12,000-lbf thrust class combustion chamber for delivery and hot-fire testing at Phillips Lab. The integrated process of investment casting directly from rapid prototype patterns dramatically reduces design-to-delivery cycle time, and greatly enhances design flexibility over conventionally processed cast or machined parts.

  17. Improved Rhenium Thrust Chambers for In-Space Propulsion Project

    National Aeronautics and Space Administration — Radiation-cooled, bipropellant thrust chambers are being considered for the ascent/descent engines and reaction control systems (RCS) for future NASA missions such...

  18. Direct thrust force measurement of pulse detonation engine

    Wahid, Mazlan Abdul; Faiz, M. Z. Ahmad; Saqr, Khalid M.

    2012-06-01

    In this paper we present the result of High-Speed Reacting Flow Laboratory (HiREF) pulse detonation engine (PDE) experimental study on direct thrust measurement. The thrust force generated by the repetitive detonation from a 50 mm inner diameter and 600 mm length tube was directly measured using load cell. Shchelkin spiral was used as an accelerator for the Deflagration to Detonation Transition (DDT) phenomenon. Propane-oxygen at stoichiometric condition was used as the combustible fuel-air mixture for the PDE. The PDE was operated at the operation frequency of 3Hz during the test. The amount of thrust force that was measured during the test reaching up to 70N. These values of thrust force were found to be fluctuating and its combustion phenomenon has been analyzed and discussed.

  19. Improved Rhenium Thrust Chambers for In-Space Propulsion Project

    National Aeronautics and Space Administration — Radiation-cooled, bipropellant thrust chambers are being considered for the ascent/descent engines and reaction control systems for NASA missions such as Mars...

  20. Nitrous Oxide Liquid Injection Thrust Vector Control System Testing Project

    National Aeronautics and Space Administration — A Nitrous Oxide-fed Liquid Thrust Vector Control system is proposed as an efficient method for vehicle attitude control during powered flight. Pulled from a N2O...

  1. Optimal Thrust Vectoring for an Annular Aerospike Nozzle Project

    National Aeronautics and Space Administration — Recent success of an annular aerospike flight test by NASA Dryden has prompted keen interest in providing thrust vector capability to the annular aerospike nozzle...

  2. Experimental Validation of a Marine Propeller Thrust Estimation Scheme

    Luca Pivano; Øyvind N. Smogeli; Tor A. Johansen; Thor Inge Fossen

    2007-01-01

    A thrust estimation scheme for a marine propeller has been experimentally tested in waves and with a device that simulates the influence of a vessel hull. The scheme is formed by a nonlinear propeller torque observer and a mapping to generate the thrust from the observed torque. The mapping includes the estimation of the advance number. This is utilized to improve the performance when the propeller is lightly loaded. The advance speed is assumed to be unknown, and only measurements of shaft s...

  3. Practical compensation for nonlinear dynamic thrust measurement system

    Chen Lin; Chen Jie; Li Jianxun

    2015-01-01

    The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network (RBF-NN), where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical ...

  4. Acoustically shielded exhaust system for high thrust jet engines

    Carey, John P. (Inventor); Lee, Robert (Inventor); Majjigi, Rudramuni K. (Inventor)

    1995-01-01

    A flade exhaust nozzle for a high thrust jet engine is configured to form an acoustic shield around the core engine exhaust flowstream while supplementing engine thrust during all flight conditions, particularly during takeoff. The flade airflow is converted from an annular 360.degree. flowstream to an arcuate flowstream extending around the lower half of the core engine exhaust flowstream so as to suppress exhaust noise directed at the surrounding community.

  5. Control of VTOL Vehicles with Thrust-direction Tilting

    Hua, Minh-Duc; Hamel, Tarek; Samson, Claude

    2013-01-01

    An approach to the control of a VTOL vehicle equipped with complementary thrust-direction tilting capabilities that nominally yield full actuation of the vehicle's position and attitude is developed. The particularity and difficulty of the control problem are epitomized by the existence of a maximal thrust-tilting angle which forbids complete and decoupled control of the vehicle's position and attitude in all situations. This problem is here addressed via the formalism of primary and secondar...

  6. Fuel optimum low-thrust elliptic transfer using numerical averaging

    Tarzi, Zahi; Speyer, Jason; Wirz, Richard

    2013-05-01

    Low-thrust electric propulsion is increasingly being used for spacecraft missions primarily due to its high propellant efficiency. As a result, a simple and fast method for low-thrust trajectory optimization is of great value for preliminary mission planning. However, few low-thrust trajectory tools are appropriate for preliminary mission design studies. The method presented in this paper provides quick and accurate solutions for a wide range of transfers by using numerical orbital averaging to improve solution convergence and include orbital perturbations. Thus, preliminary trajectories can be obtained for transfers which involve many revolutions about the primary body. This method considers minimum fuel transfers using first-order averaging to obtain the fuel optimum rates of change of the equinoctial orbital elements in terms of each other and the Lagrange multipliers. Constraints on thrust and power, as well as minimum periapsis, are implemented and the equations are averaged numerically using a Gausian quadrature. The use of numerical averaging allows for more complex orbital perturbations to be added in the future without great difficulty. The effects of zonal gravity harmonics, solar radiation pressure, and thrust limitations due to shadowing are included in this study. The solution to a transfer which minimizes the square of the thrust magnitude is used as a preliminary guess for the minimum fuel problem, thus allowing for faster convergence to a wider range of problems. Results from this model are shown to provide a reduction in propellant mass required over previous minimum fuel solutions.

  7. Application of Chaboche Model in Rocket Thrust Chamber Analysis

    Asraff, Ahmedul Kabir; Suresh Babu, Sheela; Babu, Aneena; Eapen, Reeba

    2015-12-01

    Liquid Propellant Rocket Engines are commonly used in space technology. Thrust chamber is one of the most important subsystems of a rocket engine. The thrust chamber generates propulsive thrust force for flight of the rocket by ejection of combustion products at supersonic speeds. Often double walled construction is employed for these chambers. The thrust chamber investigated here has its hot inner wall fabricated out of a high thermal conductive material like copper alloy and outer wall made of stainless steel. Inner wall is subjected to high thermal and pressure loads during operation of engine due to which it will be in the plastic regime. Main reasons for the failure of such chambers are fatigue in the plastic range (called as low cycle fatigue since the number of cycles to failure will be low in plastic range), creep and thermal ratcheting. Elasto plastic material models are required to simulate the above effects through a cyclic stress analysis. This paper gives the details of cyclic stress analysis carried out for the thrust chamber using different plasticity model combinations available in ANSYS (Version 15) FE code. The best model among the above is applied in the cyclic stress analysis of two dimensional (plane strain and axisymmetric) and three dimensional finite element models of thrust chamber. Cyclic life of the chamber is calculated from stress-strain graph obtained from above analyses.

  8. Thermodynamic analysis on specific thrust of the hydrocarbon fueled scramjet

    The aim of this work is to provide an upper estimate of the theoretical maximum specific thrust of the hydrocarbon fueled scramjet. An idealized thermodynamic cycle analysis is carried out to evaluate the performance of scramjet engines at different flight conditions, inlet pressure ratio and fuel equivalence ratio. Contrary to known Brayton cycles for the gas-turbine and ramjet engine, the inherent total pressure loss with heating must be taken into account in the high speed flow of the scramjet. The results show that the specific thrust initially grows asymptotically with fuel equivalence ratio, then reaches a maximum, and finally reduces rapidly for a given flight Mach number. The optimum inlet pressure ratio and fuel equivalence ratio at which the value of the specific thrust attains a maximum are presented. Variations of maximum specific thrust with freestream Mach numbers and material temperature limit are analyzed respectively. - Highlights: • A thermodynamic cycle analysis model is developed for the researches of scramjet. • Optimum inlet pressure ratio and equivalence ratio for Maximum specific thrust. • Specific thrust at different flight conditions and design limits are presented

  9. Development of A Thrust Stand to Meet LISA Mission Requirements

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

    2002-01-01

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

  10. Thrust stand for vertically oriented electric propulsion performance evaluation

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

  11. Thrust Stand for Vertically Oriented Electric Propulsion Performance Evaluation

    Moeller, Trevor; Polzin, Kurt A.

    2010-01-01

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

  12. Advanced hydrogen/oxygen thrust chamber design analysis

    Shoji, J. M.

    1973-01-01

    The results are reported of the advanced hydrogen/oxygen thrust chamber design analysis program. The primary objectives of this program were to: (1) provide an in-depth analytical investigation to develop thrust chamber cooling and fatigue life limitations of an advanced, high pressure, high performance H2/O2 engine design of 20,000-pounds (88960.0 N) thrust; and (2) integrate the existing heat transfer analysis, thermal fatigue and stress aspects for advanced chambers into a comprehensive computer program. Thrust chamber designs and analyses were performed to evaluate various combustor materials, coolant passage configurations (tubes and channels), and cooling circuits to define the nominal 1900 psia (1.31 x 10 to the 7th power N/sq m) chamber pressure, 300-cycle life thrust chamber. The cycle life capability of the selected configuration was then determined for three duty cycles. Also the influence of cycle life and chamber pressure on thrust chamber design was investigated by varying in cycle life requirements at the nominal chamber pressure and by varying the chamber pressure at the nominal cycle life requirement.

  13. Thrust stand for vertically oriented electric propulsion performance evaluation

    Moeller, Trevor; Polzin, Kurt A.

    2010-11-01

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

  14. Does Talocrural Joint-Thrust Manipulation Improve Outcomes After Inversion Ankle Sprain?

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

    2015-08-01

    Clinical Scenario: Ankle sprains account for roughly 10% of sport-related injuries in the active population. The majority of these injuries occur from excessive ankle inversion, leading to lateral ligamentous injury. In addition to pain and swelling, limitations in ankle range of motion (ROM) and self-reported function are common findings. These limitations are thought to be due in part to loss of mobility in the talocrural joint. Accordingly, some investigators have reported using high-velocity, low-amplitude thrust-manipulation techniques directed at the talocrural joint to address deficits in dorsiflexion (DF) ROM and function. This review was conducted to ascertain the impact of talocrural joint-thrust manipulation (TJM) on DF ROM, self-reported function, and pain in patients with a history of ankle sprain. Focused Clinical Question: In patients with a history of inversion ankle sprain, does TJM improve outcomes in DF ROM, self-reported function, and/or pain? PMID:25203437

  15. Flow shaping and thrust enhancement of sidewall bounded oscillating cantilevers

    Highlights: • Thrust and power consumption is studied for sidewall bounded cantilever oscillations. • For large sidewalls, thrust per Watt (efficiency) decreases as sidewall gap decreases. • When sidewall is carefully designed, significant flow shaping benefits can be realized. - Abstract: An oscillating cantilever is employed in a vast number of applications ranging from electronics cooling to propulsion. The motion can be driven at resonance by piezoelectrics which make it an energy efficient source of flow generation from a robust solid state device. Commonly known as piezoelectric fans, they have been the topic of numerous studies, and although many applications ultimately require mounting the cantilever within an enclosure of some form, much of the literature only considers idealized conditions, with walls far removed from the beam. Although it is commonly understood that, in general, sidewalls will help direct the flow in a desired direction, there is little knowledge into what impact this has on key performance characteristics such as power consumption, thrust, or convection enhancement. In this paper, in order to develop a strategic design approach for the enclosure, the thrust produced by a cantilever operating at resonance is quantified with two sidewalls present for a range of beam to wall spacings. Additionally, the sensitivity of the thrust on the relative location of the downstream edge of the sidewalls to the free end of the cantilever (fan tip) is experimentally investigated. It is found that the sidewall gap has little effect on thrust enhancement, except for very small gaps, and that the tip location plays a very large and interesting role in power consumption. In effect, there are cantilever tip locations where one can obtain substantial thrust enhancement with little or no extra power consumption, suggesting that flow shaping has the potential to positively impact the performance. The findings in the paper provide not only a relevant basis

  16. Dating thrust systems on Mercury: new clues on the thermal evolution of the planet

    Giacomini, Lorenza; Massironi, Matteo; Ferrari, Sabrina; Zagato, Nicola

    2016-04-01

    The global tectonic scenario of Mercury is dominated by contractional features mainly represented by lobate scarps. These structures are the expression of surface-breaking thrust faults and are linear or arcuate features widely distributed on Mercury. Since they display a broad distribution of orientations, lobate scarps are thought to be related to a global contractional strain, associated to planetary cooling (Watters et al., 1998, Geology, 26, 991-994). The age determination of these features will contribute to better constrain whether limits could be placed on when the contraction occurred. For these reasons we dated two thrust systems, located in different regions of Mercury. The first system is located at the edge between Kuiper and Beethoven quadrangle (latitude 9°20'N-23°42'S and longitude 72°73'-59°52'W). These 1500-long thrust system is constituted by several lobate scarps with a NNE-SSW orientation. The second thrust system considered in this work is the Enterprise Rupes, a 820 km-long scarp system that cuts the Rembrandt basin. We dated the activity of these systems through the buffered crater counting technique, which is used to derive absolute model ages of linear landforms (e.g. Fassett and Head, 2008, Icarus, 198, 37-56; Giacomini, et al, 2015, GSL, 401, 291-311). The results gave comparable ages for the two systems and suggest that the activity along major rupes all around planet Mercury have most probably begun before 3.5 Ga. This will give us new clues to better understanding the thermal evolution of the planet.

  17. Concealed thrusts in the Middle Gangetic plain, India - A ground penetrating radar study proves the truth against the geomorphic features supporting normal faulting

    Pati, Pitambar; Parkash, B.; Awasthi, A. K.; Acharya, Vivekanand; Singh, Satvindar

    2011-01-01

    As no evidence for thrusting has yet been reported from the Indo-Gangetic plain so, the Himalayan Frontal Thrust (HFT) has been considered to be the southern most limit of the Siwaliks to the Indo-Gangetic plain. The present study highlights the thrusting activities between the Gandak and Kosi megafan area in the Middle Gangetic plain. As these thrust sheets are concealed beneath thick sediment cover, direct surficial studies of the discontinuity planes are not possible. Further, the topographic breaks formed by the backward erosion of the uplifted thrust faces resemble normal faults with hanging walls to south. Due to gradual decreasing upliftment and/or erosion from north to south, the area shows a step like topographic appearance. Ground penetrating radar (GPR) studies reveal the concealed thrust planes beneath the sediments and the topographic breaks looking like normal faults are interpreted to be the relief created by backward erosion of the thrust sheets along with the overlying sediments. Out of four GPR profiles taken using 100 MHz antennae, three are across the topographic breaks along which most of the terminal fans are formed and one across the basement fault to study its subsurface nature. Initially GPR failed to strike any subsurface discontinuities at the topographic breaks. However, at certain distance to the south of the topographic breaks, GPR was able to strike the northerly dipping subsurface discontinuity planes. By combining the seismological signatures (distribution of earthquake epicenters) with geomorphology, these discontinuities are identified as thrusts. The GPR profiles show a gradual decrease of dip of the thrust planes from north to south across the area. Hence, by the geomorphology, seismological behavior, topography, orientation and continuity, other topographic breaks can be compared with the proven thrusts. GPR study on the basement fault revealed that the NE-SW trending basement faults are not active in the area. The compression

  18. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    Yu Lie; R.B. Bhat

    1995-01-01

    The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distri...

  19. Practical compensation for nonlinear dynamic thrust measurement system

    Chen Lin

    2015-04-01

    Full Text Available The real dynamic thrust measurement system usually tends to be nonlinear due to the complex characteristics of the rig, pipes connection, etc. For a real dynamic measuring system, the nonlinearity must be eliminated by some adequate methods. In this paper, a nonlinear model of dynamic thrust measurement system is established by using radial basis function neural network (RBF-NN, where a novel multi-step force generator is designed to stimulate the nonlinearity of the system, and a practical compensation method for the measurement system using left inverse model is proposed. Left inverse model can be considered as a perfect dynamic compensation of the dynamic thrust measurement system, and in practice, it can be approximated by RBF-NN based on least mean square (LMS algorithms. Different weights are set for producing the multi-step force, which is the ideal input signal of the nonlinear dynamic thrust measurement system. The validity of the compensation method depends on the engine’s performance and the tolerance error 0.5%, which is commonly demanded in engineering. Results from simulations and experiments show that the practical compensation using left inverse model based on RBF-NN in dynamic thrust measuring system can yield high tracking accuracy than the conventional methods.

  20. Thrust Augmentation Measurements Using a Pulse Detonation Engine Ejector

    Santoro, Robert J.; Pal, Sibtosh

    2005-01-01

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

  1. The role of tip deflection on the thrust produced by rigid flapping fins

    Huera-Huarte, Francisco; Gharib, Morteza

    2015-11-01

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

  2. Separability of drag and thrust in undulatory animals and machines

    Bale, Rahul; Neveln, Izaak D; Bhalla, Amneet Pal Singh; MacIver, Malcolm A; Patankar, Neelesh A

    2014-01-01

    For nearly a century, researchers have tried to understand the swimming of aquatic animals in terms of a balance between the forward thrust from swimming movements and drag on the body. Prior approaches have failed to provide a separation of these two forces for undulatory swimmers such as lamprey and eels, where most parts of the body are simultaneously generating drag and thrust. We nonetheless show that this separation is possible, and delineate its fundamental basis in undulatory swimmers. Our approach unifies a vast diversity of undulatory aquatic animals (anguilliform, sub-carangiform, gymnotiform, bal- istiform, rajiform) and provides design principles for highly agile bioinspired underwater vehicles. This approach has practical utility within biology as well as engineering. It is a predictive tool for use in understanding the role of the mechanics of movement in the evolutionary emergence of morphological features relating to locomotion. For example, we demonstrate that the drag-thrust separation fram...

  3. Numerical grid generation and flow simulation in SSME thrust chamber

    Gross, K. W.; Daley, P. L.; Przekwas, A. J.

    1987-01-01

    The development of liquid and solid rocket engines for future space projects demands a detailed optimization process for highly efficient performance and cost reasons. Also, testing of full size engines may not be feasible when the large size requires test facilities which are cost prohibitive or if vacuum operation cannot be acquired. For such situations only scaling from small test scale measurements or accurate analytical predictions will provide the performance prior to actually flying the mission. A rigorous approach for simulating the combustion processes in liquid rocket engines by employing a direct solution of Navier-Stokes equations within the entire volume of the thrust chambers is presented. This method is illustrated in the solution of reactive flow in the Space Shuttle Main Engine (SSME) thrust chamber. The objective is to review recent improvements in the mathematical model and to present the grid generation methodology suitable for rocket thrust chamber geometries.

  4. Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency

    I. H. Tuncer

    2004-01-01

    Full Text Available A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching motions, and the phase shift between them. Computations are performed in parallel in a work station cluster. The numerical simulations show that high thrust values may be obtained at the expense of reduced efficiency. For high efficiency in thrust generation, the induced angle of attack of the airfoil is reduced and large scale vortex formations at the leading edge are prevented. 

  5. Parametric study of thermal behavior of thrust chamber cooling channels

    Karima E. Amori

    2007-01-01

    Full Text Available A numerical investigation is adopted for two dimensional thermal analysis of rocket thrust chamber wall (RL10, employing finite difference model with iterative scheme (implemented under relaxation factor of 0.9 for convergence to compute temperature distribution within thrust chamber wall (which is composed of Nickel and Copper layers. The analysis is conducted for different boundary conditions: only convection boundary conditions then combined radiation, convection boundary conditions also for different aspect ratio (AR of cooling channel. The results show that Utilizing cooling channels of high aspect ratio leads to decrease in temperature variation across thrust chamber wall, while no effects on heat transferred to the coolant is indicated. The radiation has a considerable effect on the computed wall temperature values.

  6. Viscoplastic analysis of an experimental cylindrical thrust chamber liner

    Arya, Vinod K.; Arnold, Steven M.

    1992-01-01

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

  7. Methods for determining atypical gate valve thrust requirements

    Steele, R. Jr.; Watkins, J.C.; DeWall, K.G. [Idaho National Engineering Lab., Idaho Falls, ID (United States)] [and others

    1995-04-01

    Evaluating the performance of rising stem, wedge type, gate valves used in nuclear power plant is not a problem when the valves can be design-basis tested and their operability margins determined diagnostically. The problem occurs when they cannot be tested because of plant system limitations or when they can be tested only at some less-than-design-basis condition. To evaluate the performance of these valves requires various analytical and/or extrapolation methods by which the design-basis stem thrust requirement can be determined. This has been typically accomplished with valve stem thrust models used to calculate the requirements or by extrapolating the results from a less-than-design-basis test. The stem thrust models used by the nuclear industry to determine the opening or closing stem thrust requirements for these gate valves have generally assumed that the highest load the valve experiences during closure (but before seating) is at flow isolation and during unwedging or before flow initiation in the opening direction. However, during full-scale valve testing conducted for the USNRC, several of the valves produced stem thrust histories that showed peak closing stem forces occurring before flow isolation in the closing direction and after flow initiation in the opening direction. All of the valves that exhibited this behavior in the closing direction also showed signs of internal damage. Initially, we dismissed the early peak in the closing stem thrust requirement as damage-induced and labeled it nonpredictable behavior. Opening responses were not a priority in our early research, so that phenomenon was set aside for later evaluation.

  8. Experimental Validation of a Marine Propeller Thrust Estimation Scheme

    Luca Pivano

    2007-10-01

    Full Text Available A thrust estimation scheme for a marine propeller has been experimentally tested in waves and with a device that simulates the influence of a vessel hull. The scheme is formed by a nonlinear propeller torque observer and a mapping to generate the thrust from the observed torque. The mapping includes the estimation of the advance number. This is utilized to improve the performance when the propeller is lightly loaded. The advance speed is assumed to be unknown, and only measurements of shaft speed and motor torque have been used. Accurate results have been obtained in experimental tests.

  9. Dynamic Model for Thrust Generation of Marine Propellers

    Blanke, Mogens; Lindegaard, Karl-Petter; Fossen, Thor I.

    2000-01-01

    Mathematical models of propeller thrust and torque are traditionally based on steady state thrust and torque characteristics obtained in model basin or cavitation tunnel tests. Experimental results showed that these quasi steady state models do not accurately describe the transient phenomena in a...... thruster. A recently published dynamic model was based on the experimental observations. Describing zero advance speed conditions accurately, this model, however, does not work for a vessel at non- zero relative water speed. This paper derives a large signal dynamic model of propeller that includes the...

  10. Problems of millipound thrust measurement. The "Hansen Suspension"

    Carta, David G.

    2014-03-31

    Considered in detail are problems which led to the need and use of the 'Hansen Suspension'. Also discussed are problems which are likely to be encountered in any low level thrust measuring system. The methods of calibration and the accuracies involved are given careful attention. With all parameters optimized and calibration techniques perfected, the system was found capable of a resolution of 10 {mu} lbs. A comparison of thrust measurements made by the 'Hansen Suspension' with measurements of a less sophisticated device leads to some surprising results.

  11. Improvement of Rocket Performance by Increasing the Thrust

    This paper describes one of the methods to increase the performance of the rocket. Based of the result of the static test, the measure of the combustion chamber pressure and the thrust of the rocket will increase, if the throat diameter was decreased. The result of the static test showed that the throat diameter of the nozzle was smaller, where as the combustion chamber pressure, the thrust and the specific Impulse were higher. Its mean that the performance of the rocket was increased. (author)

  12. THE EDDY LOSSES OF A MAGNETIC THRUST BEARING

    徐华; 王艳

    2004-01-01

    Accurate calculations of losses associated with the operation of magnetic bearings are particularly important for high speed applications where the rotor losses are expected to be large and for some particular applications where even low power losses will be critical. Power losses in the magnetic thrust bearing is often neglected, but if there is misaligned in the rotor and bearing, the magnetic field in the thrust bearing is no longer axisymmetric one, or the dynamic control current in the winding is time dependent one, eddy currents are caused to flow inside the conducting material, then the power losses are very important for magnetic bearing design. This paper presents an analytical model of a thrust magnetic bearing, and the magnetic fields, forces and losses of thrust magnetic bearing are calculated. In the calculations the frequency of dynamic control current is up to 1000Hz, rotating speed is from 60rpm to 1200rpm, and the non-linearity of material is also taken into consideration. The results shows that if the magnetic field is not saturation, the eddy losses is proportional to dynamic control current frequency and a square function of dynamic control current, and also 5/2 power function of shaft's speed.

  13. The Effect of Atmospheric Pressure on Rocket Thrust -- Part I.

    Leitner, Alfred

    1982-01-01

    The first of a two-part question asks: Does the total thrust of a rocket depend on the surrounding pressure? The answer to this question is provided, with accompanying diagrams of rockets. The second part of the question (and answer) are provided in v20 n7, p479, Oct 1982 of this journal. (Author/JN)

  14. Blueschist-facies metamorphism related to regional thrust faulting

    Blake, M.C., Jr.; Irwin, W.P.; Coleman, R.G.

    1969-01-01

    Rocks of the blueschist (glaucophane schist) facies occur throughout the world in narrow tectonic belts associated with ultramafic rocks. In the Coast Range province of California, blueschist rocks are devloped in the eugeosynclinal Franciscan Formation of Late Mesozoic age. The blueschist rocks form a narrow belt for more than 800 km along the eastern margin of this province and commonly are separated from rocks of an overlying thrust plate by serpentinite. Increasing metamorphism upward toward the thrust fault is indicated mineralogically by a transition from pumpellyite to lawsonite and texturally by a transition from metagraywacke to schist. The blueschist metamorphism probably occurred during thrusting in a zone of anomalously high water pressure in the lower plate along the sole of the thrust fault. This tectonic mode of origin for blueschist differs from the generally accepted hypothesis involving extreme depth of burial. Other belts of blueschist-facies rocks, including the Sanbagawa belt of Japan, the marginal synclinal belt of New Zealand, and the blueschist-ultramafic belts of Venezuela, Kamchatka, Ural mountains, and New Caledonia have similar geologic relations and might be explained in the same manner. ?? 1969.

  15. Separability of drag and thrust in undulatory animals and machines

    Bale, Rahul; Shirgaonkar, Anup A.; Neveln, Izaak D.; Bhalla, Amneet Pal Singh; Maciver, Malcolm A.; Patankar, Neelesh A.

    2014-12-01

    For nearly a century, researchers have tried to understand the swimming of aquatic animals in terms of a balance between the forward thrust from swimming movements and drag on the body. Prior approaches have failed to provide a separation of these two forces for undulatory swimmers such as lamprey and eels, where most parts of the body are simultaneously generating drag and thrust. We nonetheless show that this separation is possible, and delineate its fundamental basis in undulatory swimmers. Our approach unifies a vast diversity of undulatory aquatic animals (anguilliform, sub-carangiform, gymnotiform, bal-istiform, rajiform) and provides design principles for highly agile bioinspired underwater vehicles. This approach has practical utility within biology as well as engineering. It is a predictive tool for use in understanding the role of the mechanics of movement in the evolutionary emergence of morphological features relating to locomotion. For example, we demonstrate that the drag-thrust separation framework helps to predict the observed height of the ribbon fin of electric knifefish, a diverse group of neotropical fish which are an important model system in sensory neurobiology. We also show how drag-thrust separation leads to models that can predict the swimming velocity of an organism or a robotic vehicle.

  16. Efficient Optimization of Low-Thrust Spacecraft Trajectories

    Lee, Seungwon; Fink, Wolfgang; Russell, Ryan; Terrile, Richard; Petropoulos, Anastassios; vonAllmen, Paul

    2007-01-01

    A paper describes a computationally efficient method of optimizing trajectories of spacecraft driven by propulsion systems that generate low thrusts and, hence, must be operated for long times. A common goal in trajectory-optimization problems is to find minimum-time, minimum-fuel, or Pareto-optimal trajectories (here, Pareto-optimality signifies that no other solutions are superior with respect to both flight time and fuel consumption). The present method utilizes genetic and simulated-annealing algorithms to search for globally Pareto-optimal solutions. These algorithms are implemented in parallel form to reduce computation time. These algorithms are coupled with either of two traditional trajectory- design approaches called "direct" and "indirect." In the direct approach, thrust control is discretized in either arc time or arc length, and the resulting discrete thrust vectors are optimized. The indirect approach involves the primer-vector theory (introduced in 1963), in which the thrust control problem is transformed into a co-state control problem and the initial values of the co-state vector are optimized. In application to two example orbit-transfer problems, this method was found to generate solutions comparable to those of other state-of-the-art trajectory-optimization methods while requiring much less computation time.

  17. Why style matters - uncertainty and structural interpretation in thrust belts.

    Butler, Rob; Bond, Clare; Watkins, Hannah

    2016-04-01

    Structural complexity together with challenging seismic imaging make for significant uncertainty in developing geometric interpretations of fold and thrust belts. Here we examine these issues and develop more realistic approaches to building interpretations. At all scales, the best tests of the internal consistency of individual interpretations come from structural restoration (section balancing), provided allowance is made for heterogeneity in stratigraphy and strain. However, many existing balancing approaches give misleading perceptions of interpretational risk - both on the scale of individual fold-thrust (trap) structures and in regional cross-sections. At the trap-scale, idealised models are widely cited - fault-bend-fold, fault-propagation folding and trishear. These make entirely arbitrary choices for fault localisation and layer-by-layer deformation: precise relationships between faults and fold geometry are generally invalidated by real-world conditions of stratigraphic variation and distributed strain. Furthermore, subsurface predictions made using these idealisations for hydrocarbon exploration commonly fail the test of drilling. Rarely acknowledged, the geometric reliability of seismic images depends on the assigned seismic velocity model, which in turn relies on geological interpretation. Thus iterative approaches are required between geology and geophysics. The portfolio of commonly cited outcrop analogues is strongly biased to examples that simply conform to idealised models - apparently abnormal structures are rarely described - or even photographed! Insight can come from gravity-driven deep-water fold-belts where part of the spectrum of fold-thrust complexity is resolved through seismic imaging. This imagery shows deformation complexity in fold forelimbs and backlimbs. However, the applicability of these, weakly lithified systems to well-lithified successions (e.g. carbonates) of many foreland thrust belts remains conjectural. Examples of

  18. A 10 nN resolution thrust-stand for micro-propulsion devices

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

  19. A 10 nN resolution thrust-stand for micro-propulsion devices

    Chakraborty, Subha; Courtney, Daniel G.; Shea, Herbert, E-mail: herbert.shea@epfl.ch [Microsystems for Space Technologies Laboratory (LMTS), Ecole Polytechnique Federale de Lausanne (EPFL), Neuchatel (Switzerland)

    2015-11-15

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

  20. Cataclasites-ultracataclasites in a major thrust zone: Gaissa Thrust, N. Norwegian Caledonides.

    Rice, A. Hugh N.; Grasemann, Bernhard

    2015-04-01

    Narrow fault zones of intense deformation imply strain localisation. This is superbly shown by the ~horizontal Caledonian basal décollement in N. Norway, where ~127 km of top E-to-ESE thrust displacement is concentrated in a ~3 cm thick principle slip zone within lower strain hanging wall and footwall cataclasites less than a few centimetres thick. A scan of a transport-direction parallel 8.5x11.5cm thin-section of the fault is enlarged to 0.7x1.0m in the poster. The Caledonian external imbricate zone here places anchizone pre-Marinoan quartzite/shales onto diagenetic-zone post-Gaskiers red/green shales, silts and fine sandstones. Carbonates are absent. The displacement was estimated from balanced cross-sections and branch-line restorations. In the hangingwall cataclastic zone, a coarse qtz-rich/clay-rich cataclastic compositional layering dips at thin-section), separating type 1 layers. Boundaries between the three types are generally sharp (principle slip surfaces). The excision of some layers and one markedly irregular boundary between type 2 and 3 layers indicates late movement oblique to the regional transport direction. No evidence of pseudotachylite has been seen. The footwall cataclastic zone is more disturbed than in the hanging wall. Variations in cataclasites define an irregular, poor compositional layering. No sedimentary features are preserved. Foreland dipping fractures (thin fractures, some with very minor offsets, cut across the whole fault. Thicker, irregular detachment parallel fractures also occur in the principle slip zone. These very late fractures, as well as minor voids in the principle slip zone, are filled with carbonate. Further work is in progress on the age, chemistry and textural evolution of the fault.

  1. Seafloor Geodetic Approaches to Subduction Thrust Earthquakes

    Fujimoto, H.

    2014-03-01

    Observation systems and some observed results of seafloor geodesy are reviewed with a focus on the research activities of Japanese groups, especially those of Tohoku University. Seafloor acoustic ranging has been adopted as the simplest way to continuously monitor local crustal activities. The GPS-Acoustic (GPSA) method has been the most important for seafloor positioning. It seems that commercial technologies can be used to lessen the considerable differences in repeatability and spatio-temporal resolution of GPSA and land based GPS. Ocean bottom pressure sensors have been used to continuously monitor vertical crustal movements. Improvements in the resolution and long-term stability of pressure sensors will lead to monitoring slow slip events and interplate locking. Ocean bottom and underwater gravimeters have been developed for precise gravity mapping and monitoring mass change beneath the seafloor. The 2011 Tohoku-oki earthquake is an historical event demonstrating that seafloor geodetic observations are crucial to understanding the mechanism of giant earthquakes. Coseismic displacements detected through geodetic observations on the seafloor have indicated huge slips on the shallow part of the plate boundary. A slow slip event near the zone of the coseismic slip preceding the main event has been detected from slight pressure variations. This illustrates the importance of real-time monitoring with a cabled seafloor observatory, which is also a key to establishing a reliable early tsunami warning system.

  2. Advances in Thrust-Based Emergency Control of an Airplane

    Creech, Gray; Burken, John J.; Burcham, Bill

    2003-01-01

    Engineers at NASA's Dryden Flight Research Center have received a patent on an emergency flight-control method implemented by a propulsion-controlled aircraft (PCA) system. Utilizing the preexisting auto-throttle and engine-pressure-ratio trim controls of the airplane, the PCA system provides pitch and roll control for landing an airplane safely without using aerodynamic control surfaces that have ceased to function because of a primary-flight-control-system failure. The installation of the PCA does not entail any changes in pre-existing engine hardware or software. [Aspects of the method and system at previous stages of development were reported in Thrust-Control System for Emergency Control of an Airplane (DRC-96-07), NASA Tech Briefs, Vol. 25, No. 3 (March 2001), page 68 and Emergency Landing Using Thrust Control and Shift of Weight (DRC-96-55), NASA Tech Briefs, Vol. 26, No. 5 (May 2002), page 58.]. Aircraft flight-control systems are designed with extensive redundancy to ensure low probabilities of failure. During recent years, however, several airplanes have exhibited major flight-control-system failures, leaving engine thrust as the last mode of flight control. In some of these emergency situations, engine thrusts were successfully modulated by the pilots to maintain flight paths or pitch angles, but in other situations, lateral control was also needed. In the majority of such control-system failures, crashes resulted and over 1,200 people died. The challenge lay in creating a means of sufficient degree of thrust-modulation control to safely fly and land a stricken airplane. A thrust-modulation control system designed for this purpose was flight-tested in a PCA an MD-11 airplane. The results of the flight test showed that without any operational control surfaces, a pilot can land a crippled airplane (U.S. Patent 5,330,131). The installation of the original PCA system entailed modifications not only of the flight-control computer (FCC) of the airplane but

  3. Scale independence of décollement thrusting

    McBride, John H.; Pugin, Andre J.M.; Hatcher, Robert D., Jr.

    2007-01-01

    Orogen-scale décollements (detachment surfaces) are an enduring subject of investigation by geoscientists. Uncertainties remain as to how crustal convergence processes maintain the stresses necessary for development of low-angle fault surfaces above which huge slabs of rock are transported horizontally for tens to hundreds of kilometers. Seismic reflection profiles from the southern Appalachian crystalline core and several foreland fold-and-thrust belts provide useful comparisons with high-resolution shallow-penetration seismic reflection profiles acquired over the frontal zone of the Michigan lobe of the Wisconsinan ice sheet northwest of Chicago, Illinois. These profiles provide images of subhorizontal and overlapping dipping reflections that reveal a ramp-and-flat thrust system developed in poorly consolidated glacial till. The system is rooted in a master décollement at the top of bedrock. These 2–3 km long images contain analogs of images observed in seismic reflection profiles from orogenic belts, except that the scale of observation in the profiles in glacial materials is two orders of magnitude less. Whereas the décollement beneath the ice lobe thrust belt lies ∼70 m below thrusted anticlines having wavelengths of tens of meters driven by an advancing ice sheet, seismic images from overthrust terranes are related to lithospheric convergence that produces décollements traceable for thousands of kilometers at depths ranging from a few to over 10 km. Dual vergence or reversals in vergence (retrocharriage) that developed over abrupt changes in depth to the décollement can be observed at all scales. The strikingly similar images, despite the contrast in scale and driving mechanism, suggest a scale- and driving mechanism–independent behavior for décollement thrust systems. All these systems initially had the mechanical properties needed to produce very similar geometries with a compressional driving mechanism directed subparallel to Earth's surface

  4. Early weakening processes inside thrust fault

    Lacroix, B.; Tesei, T.; Oliot, E.; Lahfid, A.; Collettini, C.

    2015-07-01

    Observations from deep boreholes at several locations worldwide, laboratory measurements of frictional strength on quartzo-feldspathic materials, and earthquake focal mechanisms indicate that crustal faults are strong (apparent friction μ ≥ 0.6). However, friction experiments on phyllosilicate-rich rocks and some geophysical data have demonstrated that some major faults are considerably weaker. This weakness is commonly considered to be characteristic of mature faults in which rocks are altered by prolonged deformation and fluid-rock interaction (i.e., San Andreas, Zuccale, and Nankai Faults). In contrast, in this study we document fault weakening occurring along a marly shear zone in its infancy (<30 m displacement). Geochemical mass balance calculation and microstructural data show that a massive calcite departure (up to 50 vol %) from the fault rocks facilitated the concentration and reorganization of weak phyllosilicate minerals along the shear surfaces. Friction experiments carried out on intact foliated samples of host marls and fault rocks demonstrated that this structural reorganization lead to a significant fault weakening and that the incipient structure has strength and slip behavior comparable to that of the major weak faults previously documented. These results indicate that some faults, especially those nucleating in lithologies rich of both clays and high-solubility minerals (such as calcite), might experience rapid mineralogical and structural alteration and become weak even in the early stages of their activity.

  5. Global Optimization of Low-Thrust Interplanetary Trajectories Subject to Operational Constraints

    Englander, Jacob Aldo; Vavrina, Matthew; Hinckley, David

    2016-01-01

    Low-thrust electric propulsion provides many advantages for mission to difficult targets-Comets and asteroids-Mercury-Outer planets (with sufficient power supply)Low-thrust electric propulsion is characterized by high power requirements but also very high specific impulse (Isp), leading to very good mass fractions. Low-thrust trajectory design is a very different process from chemical trajectory.

  6. Friction and Lubrication of Large Tilting-Pad Thrust Bearings

    Michał Wasilczuk

    2015-04-01

    Full Text Available Fluid film bearings have been extensively used in the industry because of their unbeatable durability and extremely low friction coefficient, despite a very low coefficient of friction dissipation of energy being noticeable, especially in large bearings. Lubricating systems of large tilting pad thrust bearings utilized in large, vertical shaft hydrogenerators are presented in this paper. A large amount of heat is generated due to viscous shearing of the lubricant large tilting pad thrust bearings, and this requires systems for forced cooling of the lubricant. In the dominant bath lubrication systems, cooling is realized by internal coolers or external cooling systems, with the latter showing some important advantages at the cost of complexity and also, potentially, lower reliability. Substantial losses in the bearings, reaching 1 MW in extreme cases, are a good motivation for the research and development aimed at reducing them. Some possible methods and their potential efficiency, along with some effects already documented, are also described in the paper.

  7. Research on Service Life Prediction Model of Thrust Needle Bearing

    Li Wei

    2012-11-01

    Full Text Available Needle roller thrust bear is small in size and of high ability in load bearing, therefore it is widely used in fields of aviation and automobile etc.  But the relation between their service life and pre-tightening torque is not very clear, so the using design of the bear depends mainly on experience of engineer, because of lack of references. In the paper, the theoretical analysis on relation between torque and load is done, special wearing test instrument is developed and wearing test of thrust needle bear is conducted. Based on the results of the test, mathematical model of relation between the losing amount of pre-tightening torque and the pre-tightening torque is built, based on which use of the bear in engineering will be more reasonable, and their pre-tightening torque will be given more accurately.

  8. Entrainment and thrust augmentation in pulsatile ejector flows

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

    1981-01-01

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

  9. Propellant management for low thrust chemical propulsion systems

    Hamlyn, K. M.; Dergance, R. H.; Aydelott, J. C.

    1981-01-01

    Low-thrust chemical propulsion systems (LTPS) will be required for orbital transfer of large space systems (LSS). The work reported in this paper was conducted to determine the propellant requirements, preferred propellant management technique, and propulsion system sizes for the LTPS. Propellants were liquid oxygen (LO2) combined with liquid hydrogen (LH2), liquid methane or kerosene. Thrust levels of 100, 500, and 1000 lbf were combined with 1, 4, and 8 perigee burns for transfer from low earth orbit to geosynchronous earth orbit. This matrix of systems was evaluated with a multilayer insulation (MLI) or a spray-on-foam insulation. Vehicle sizing results indicate that a toroidal tank configuration is needed for the LO2/LH2 system. Multiple perigee burns and MLI allow far superior LSS payload capability. Propellant settling, combined with a single screen device, was found to be the lightest and least complex propellant management technique.

  10. Jet-Engine Exhaust Nozzle With Thrust-Directing Flaps

    Wing, David J.

    1996-01-01

    Convergent/divergent jet-engine exhaust nozzle has cruciform divergent passage containing flaps that move to deflect flow of exhaust in either or both planes perpendicular to main fore-and-aft axis of undeflected flow. Prototype of thrust-vector-control nozzles installed in advanced, high-performance airplanes to provide large pitching (usually, vertical) and yawing (usually, horizontal) attitude-control forces independent of attitude-control forces produced by usual aerodynamic control surfaces.

  11. Maneuver analysis for spinning thrusting spacecraft and spinning tethered spacecraft

    Martin, Kaela M.

    During axial thrusting of a spin-stabilized spacecraft undergoing orbital injections or control maneuvers, misalignments and center-of-mass offset create undesired body-fixed torques. The effects of the body-fixed torques, which in turn cause velocity pointing errors, can be reduced by ramping up (and then ramping down) the thruster. The first topic discussed in this thesis derives closed-form solutions for the angular velocity, Euler angles, inertial velocity, and inertial displacement solutions with nonzero initial conditions. Using the closed-form solutions, the effect of variations in the spin-axis moment of inertia and spin-rate on the spacecraft velocity pointing error are shown. The analytical solutions closely match numerical simulations. The next topic considers various ramp-up profiles (including parabolic, cosine, logarithmic, exponential, and cubic) to heuristically find a suboptimal solution to reduce the velocity pointing error. Some of the considered cosine, logarithmic, exponential, parabolic, and cubic profiles drive the velocity pointing error to nearly zero and hence qualify as effective solutions. The third topic examines a large tethered spacecraft that produces artificial gravity with the propulsion system on one end of the tether. Instead of thrusting through the center of mass, the offset thrust occurs at an angle to the tether which is held in the desired direction by changing the spin rate to compensate for decreasing propellant mass. The dynamics and control laws of the system are derived for constant, time-varying, planar, and non-planar thrust as well as spin-up maneuvers. The final topic discusses how the Bodewadt solution of a self-excited rigid body is unable to accurately predict the motion compared to a numerical integration of the equations of motion.

  12. Displaced geostationary orbits using hybrid low-thrust propulsion

    Heiligers, Jeannette; McInnes, Colin R.; Biggs, James D.; Ceriotti, Matteo

    2012-01-01

    In this paper, displaced geostationary orbits using hybrid low-thrust propulsion, a complementary combination of Solar Electric Propulsion (SEP) and solar sailing, are investigated to increase the capacity of the geostationary ring that is starting to become congested. The SEP propellant consumption is minimized in order to maximize the mission lifetime by deriving semi-analytical formulae for the optimal steering laws for the SEP and solar sail accelerations. By considering the spacecraft ma...

  13. Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency

    Tuncer, I.H.; Kay, M.

    2004-01-01

    A numerical optimization algorithm based on the steepest decent along the variation of the optimization function is implemented for maximizing the thrust and/or propulsive efficiency of a single flapping airfoil. Unsteady, low speed laminar flows are computed using a Navier-Stokes solver on moving overset grids. The flapping motion of the airfoil is described by a combined sinusoidal plunge and pitching motion. Optimization parameters are taken to be the amplitudes of the plunge and pitching ...

  14. Low-thrust chemical propulsion system pump technology

    Meadville, J. W.

    1980-01-01

    A study was conducted within the thrust range 450 to 9000 N (100 to 2000 pounds). Performance analyses were made on centrifugal, pitot, Barske, drag, Tesla, gear, piston, lobe, and vane pumps with liquid hydrogen, liquid methane, and liquid oxygen as propellants. Gaseous methane and hydrogen driven axial impulse turbines, vane expanders, piston expanders, and electric motors were studied as drivers. Data are presented on performance, sizes, weights, and estimated service lives and costs.

  15. Collision Avoidance for Satellite Orbits and Low Thrust Transitions

    Assmann, Kaja

    2008-01-01

    This thesis presents a capacious collision avoidance method named COLA. The method has been designed to predict collisions for Earth orbiting spacecraft (S/C) with other space-born objects. The COLA method is able to detect the point of time and the probability of collisions for objects flying on all kinds of Earth orbits, including high impulse and low thrust transfers. To guarantee an effective solution of all tasks in the process of the collision prediction, the COLA method ...

  16. Characterization of Space Shuttle Reusable Rocket Motor Static Test Stand Thrust Measurements

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

    2003-01-01

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

  17. Electric sail control mode for amplified transverse thrust

    Toivanen, Petri; Envall, Jouni

    2014-01-01

    The electric solar wind sail produces thrust by centrifugally spanned high voltage tethers interacting with the solar wind protons. The sail attitude can be controlled and attitude maneuvers are possible by tether voltage modulation synchronous with the sail rotation. Especially, the sail can be inclined with respect to the solar wind direction to obtain transverse thrust to change the osculating orbit angular momentum. Such an inclination has to be maintained by a continual control voltage modulation. Consequently, the tether voltage available for the thrust is less than the maximum voltage provided by the power system. Using a spherical pendulum as a model for a single rotating tether, we derive analytical estimations for the control efficiency for two separate sail control modes. One is a continuous control modulation that corresponds to strictly planar tether tip motion. The other is an on-off modulation with the tether tip moving along a closed loop on a saddle surface. The novel on-off mode is introduce...

  18. Camera Layout Design for the Upper Stage Thrust Cone

    Wooten, Tevin; Fowler, Bart

    2010-01-01

    Engineers in the Integrated Design and Analysis Division (EV30) use a variety of different tools to aid in the design and analysis of the Ares I vehicle. One primary tool in use is Pro-Engineer. Pro-Engineer is a computer-aided design (CAD) software that allows designers to create computer generated structural models of vehicle structures. For the Upper State thrust cone, Pro-Engineer was used to assist in the design of a layout for two camera housings. These cameras observe the separation between the first and second stage of the Ares I vehicle. For the Ares I-X, one standard speed camera was used. The Ares I design calls for two separate housings, three cameras, and a lighting system. With previous design concepts and verification strategies in mind, a new layout for the two camera design concept was developed with members of the EV32 team. With the new design, Pro-Engineer was used to draw the layout to observe how the two camera housings fit with the thrust cone assembly. Future analysis of the camera housing design will verify the stability and clearance of the camera with other hardware present on the thrust cone.

  19. The NPL/ESA Micro-Newton Thrust Balance

    Hughes, Ben; Perez Luna, Jaime

    2012-07-01

    Europe is pursuing a number of unique science missions which require extremely high performance micro- propulsion systems to perform precision attitude control to meet their challenging scientific goals. A number of different propulsion systems are under development to try and meet these needs, including systems based on FEEP, mini-ion and cold gas thruster technologies. The critical performance requirements for the thrusters are related to thrust accuracy, dynamic response and noise, where very challenging requirements are set. Although it is anticipated that the thruster technologies can meet these challenging requirements, verification of these performances by test presents its own difficulties, since the magnitude of the thrust noise required is close to the limit of available measurement devices, and the practicalities of testing thrusters under vacuum provide their own challenges. To address the complex measurement requirements, the UK’s National Physical Laboratory (NPL) is working closely with ESTEC to develop a state-of-the-art thrust balance that will provide traceable (to international measurement standards) measurements with a target measurement uncertainty of 1 μN (k = 2) and measurement bandwidth of 0 Hz to 10 Hz. The paper will focus on the design of the instrument, the detrimental effects of external vibration noise on the measurement, how this problem is being addressed and how we determine the measurement uncertainty in the presence of noise.

  20. Polyphase tertiary fold-and-thrust tectonics in the Belluno Dolomites: new mapping, kinematic analysis, and 3D modelling

    Chistolini, Filippo; Bistacchi, Andrea; Massironi, Matteo; Consonni, Davide; Cortinovis, Silvia

    2014-05-01

    performed a dip-domain analysis that allowed to categorize the different fold limbs and reduce the uncertainty in the reconstruction of the fault network topology in map view. This enabled us to reconstruct a high-quality, low-uncertainty 3D structural and geological model, which unambiguously proves that deformations with a top-to-WSW Dinaric transport direction propagate farther to the west than previously supposed in this part of the Southern Alps. Our new structural reconstruction of the Vajont valley have also clarified the structural control on the 1963 catastrophic landslide (which caused over 2000 losses). Besides being a challenging natural laboratory for testing analysis and modelling methodologies to be used when reconstructing in 3D this kind of complex interference structures, the Vajont area also provides useful clues on the still-enigmatic structures in the frontal part of the Friuli-Venetian Southern Alps, buried in the Venetian Plain foredeep. These include active seismogenic thrust-faults and, at the same time, represent a growing interest for the oil industry.

  1. Coupled Dynamics of a Rotor-Journal Bearing System Equipped with Thrust Bearings

    Yu Lie

    1995-01-01

    Full Text Available The rotordynamic coefficients of fixed-pad thrust bearing are introduced and calculated by using the out-domain method, and a general analysis method is developed to investigate the coupled dynamics of a rotor equipped with journal and thrust bearings simultaneously. Considerations include the effects of static tilt parameters of the rotor on rotordynamic coefficients of thrust bearing and the action of thrust bearing on system dynamics. It is shown that thrust bearing changes the load distribution of journal bearings and the static deflection of the rotor and delays the instability of the system considerably in lateral shaft vibration.

  2. How the structure of a continental margin affects the development of a fold and thrust belt. 1: A case study in south-central Taiwan

    Brown, Dennis; Alvarez-Marron, Joaquina; Biete, Cristina; Camanni, Giovanni; Kuo-Chen, Hao; Ho, Chun-Wei

    2016-04-01

    depth, but becoming especially prominent at 12 km and 16 km depth, there is an embayment of relatively high Vp that can be interpreted as the onshore projection of a basement high that occurs between the Mesozoic basement shelf break and the Taihsi Basin. Southward, there is a notable northeast-southwest-oriented increase in seismicity across the on land projection of the Mesozoic basement shelf break, with seismicity predominantly located beneath the Alishan Ranges, the highest topography in this part of the mountain belt. The topography also shows a pronounced re-entrant that coincides with the orientation and onshore projection of the Mesozoic basement shelf break that extends northeastward across the Western Foothills and into the Hsuehshan Range. The shallow structure of south-central Taiwan contains a number of features, such as changes in structural grain, or basement involvement in the deformation, that can be attributed to the presence of pre-existing structures in the Eurasian continental margin as it enters into the deformation of the Taiwan fold and thrust belt.

  3. Return period of great Himalayan earthquakes in Eastern Nepal: evidence from the Patu and Bardibas strands of the Main Frontal Thrust

    Bollinger, L.; Tapponnier, P.; Sapkota, S. N.; Klinger, Y.; Rizza, M.; van der Woerd, J.

    2013-12-01

    The return period of large Himalayan earthquakes remains poorly constrained. Despite the repeated destruction of ancient cities in and afoot the mountain range, attested by historical chronicles, no definitive link between known events and specific segments of the Main Himalayan Thrust system has been established. Furthermore, few paleo-seismological records have unambiguously documented the occurrence of multiple, similar events at the same location along that system. In east-central Nepal, however, primary ruptures and modern surface deformation due to the great 1255 and 1934 earthquakes were recently discovered in the Sir Khola valley. The ruptures are associated with a long record of multiple terraces uplifted by the Main Frontal Thrust. To investigate further the recent slip history of the thrust in that area, we surveyed in detail its two main, overlapping splays: the Patu Thrust to the North, and the Bardibas Thrust, ≈ 5 km to the South. We updated the regional geomorphic and neo-tectonic map of active faulting and folding, acquired three shallow, ≈ 1.5 km-long, 400 m-deep seismic profiles, refreshed a natural rivercut cliff, excavated trenches and dated recent sedimentary records across both structures. In addition to the 1255 and 1934 earthquakes, the uplift of terraces in the hanging-wall of the Patu thrust requires two more events in the last 2400 +/-100 years BP. Given the thrust deep geometry and dip, and the hangingwall uplift rate, each event on the Patu splay appears to have accommodated 9 to 12.5 m of slip. Trenching of a flexural fold scarp on the Bardibas splay suggests that growth events generated transient episodes of proximal colluvial deposition, augmenting the number of past earthquakes recorded to a minimum of 6 in the last 4500 years. Overall, assuming that both splays rupture coevally, our observations thus imply that the average return period of great Himalayan earthquakes in eastern Nepal is between [700-933] years and 907 +/- 150

  4. The foreland thrust belt in northwestern margin of Yangtze platform and the coalfield structure feature

    Zhang, D.; Jing, Y. [Guangdon Bureau of Coal Geology (China)

    1997-12-01

    The accumulation and occurrence of coal resources in Yangtze platform and its northwest margin are controlled by the formation and evolution of foreland thrust belt in its northwest margin. The foreland thrust belt can be divided into root zone, middle zone and front zone. There is no coal accumulation root zone, the industrial coal resources are occurred in middle zone, and the coal resources occurred in the front zone are buried deeply. The coalfield structure deformation which is characterized by the imbricate thrusts, duplex thrust, parallel fold, inclined fold, klippen, thrust sheets and fault block, is resulted from the compressive stress of foreland thrust belt. The formation of the thrust belt is the result of long-time evolution of Tethys domain, in which the plates had collided three times along three sutures. 2 refs., 5 figs.

  5. Crustal Stress State and Seismic Hazard along Southwest Segment of the Longmenshan Thrust Belt after Wenchuan Earthquake

    Xianghui Qin; Chengxuan Tan; Qunce Chen; Manlu Wu; Chengjun Feng

    2014-01-01

    The crustal stress and seismic hazard estimation along the southwest segment of the Longmenshan thrust belt after the Wenchuan Earthquake was conducted by hydraulic fracturing for in-situ stress measurements in four boreholes at the Ridi, Wasigou, Dahegou, and Baoxing sites in 2003, 2008, and 2010. The data reveals relatively high crustal stresses in the Kangding region (Ridi, Wasigou, and Dahegou sites) before and after the Wenchuan Earthquake, while the stresses were relatively low in the short time after the earthquake. The crustal stress in the southwest of the Longmenshan thrust belt, especially in the Kangding region, may not have been totally released during the earthquake, and has since increased. Furthermore, the Coulomb failure criterion and Byerlee’s law are adopted to analyzed in-situ stress data and its implications for fault activity along the southwest segment. The magnitudes of in-situ stresses are still close to or exceed the expected lower bound for fault activity, revealing that the studied region is likely to be active in the future. From the conclusions drawn from our and other methods, the southwest segment of the Longmenshan thrust belt, especially the Baoxing region, may present a future seismic hazard.

  6. Configuration maintaining control of three-body ring tethered system based on thrust compensation

    Huang, Panfeng; Liu, Binbin; Zhang, Fan

    2016-06-01

    Space multi-tethered systems have shown broad prospects in remote observation missions. This paper mainly focuses on the dynamics and configuration maintaining control of space spinning three-body ring tethered system for such mission. Firstly, we establish the spinning dynamic model of the three-body ring tethered system considering the elasticity of the tether using Newton-Euler method, and then validate the suitability of this model by numerical simulation. Subsequently, LP (Likins-Pringle) initial equilibrium conditions for the tethered system are derived based on rigid body's equilibrium theory. Simulation results show that tether slack, snapping and interaction between the tethers exist in the three-body ring system, and its' configuration can not be maintained without control. Finally, a control strategy based on thrust compensation, namely thrust to simulate tether compression under LP initial equilibrium conditions is designed to solve the configuration maintaining control problem. Control effects are verified by numerical simulation compared with uncontrolled situation. Simulation results show that the configuration of the three-body ring tethered system could maintain under this active control strategy.

  7. Deformation history during chain building deduced by outcrop structural analysis: The case of the Sicilian fold-and-thrust belt (Central Mediterranean)

    Napoli, G.; Nigro, F.; Favara, R.; Renda, P.; Salvaggio, G.

    2015-11-01

    The Sicilian fold-and-thrust belt is located in the central Mediterranean area, and it represents the south-eastern arcuate segment of the Apennine-Maghrebide orogen. The tectonic evolution of the Sicilian belt is documented after outcrop analysis of small-scale structural features carried out throughout the region. Results are consistent with the following four main deformation stages having affected the study area, from the oldest to the youngest: (i) multilayer weakening; (ii) folding-and-thrusting, (iii) extension, and (iv) renewed thrusting. The first deformation stage included three different substages (layer-parallel shortening, bed-parallel simple shear and fold nucleation), the second one by both thrusting and fold amplification and tightening. The third deformation stage involved re-activation of the pre-existing mechanical discontinuities and formation of low-to-high angle normal faults. Out-of-sequence thrusting postdated the aforementioned extensional stage, and formed the latest orogenic deformation stage that affected the Sicilian belt.

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

    Yetter, Jeffrey A.

    1995-01-01

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

  9. Surface ruptures of large Himalayan earthquakes in Western Nepal: Evidence along a reactivated strand of the Main Boundary Thrust

    Hossler, T.; Bollinger, L.; Sapkota, S. N.; Lavé, J.; Gupta, R. M.; Kandel, T. P.

    2016-01-01

    The chronology of the seismic ruptures along the active faults of Western Nepal remains almost unconstrained despite their high seismogenic potential. We present here a slip history of one of these structures, a 120 km-long reactivated segment of the Main Boundary Thrust named the Surkhet-Gorahi fault. This slip history is based on geomorphologic and neotectonic mapping of active faults deduced from the analysis of a high resolution total station digital elevation model and 15 detrital charcoals radiocarbon ages constraining the age of deposition or abandonment of 4 alluvial terraces of the Bheri river in Botechaur. Our results show that the last two earthquakes occurred on this fault after 1860 and 640 BP, respectively, and accommodated slip greater than 8 m each, a value corresponding to the incremental vertical offset of the terraces. Such events released a significant part of the slip deficit accumulated on the Main Himalayan thrust fault. However, given the geometry of this fault system as well as the date of occurrence of the last events, the ruptures could be associated with major earthquakes also rupturing the Main Frontal Thrust, such as the great 1505 earthquake.

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

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

    2016-01-01

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

  11. Minimum Thrust Load Control for Floating Wind Turbine

    Christiansen, Søren; Bak, Thomas; Knudsen, Torben

    2012-01-01

    become profitable, capable of accessing unexploited wind resources while reaching regions of new consumers. However, floating wind turbines are subject to reduced structural stiffness which results in instabilities when standard wind turbine control systems are applied. Based on optimal control, this paper...... presents a new minimum thrust control strategy capable of stabilizing a floating wind turbine. The new control strategy explores the freedom of variable generator speed above rated wind speed. A comparison to the traditional constant speed strategy, shows improvements in structural fore-aft oscillations and...... power stability when using the new control strategy....

  12. Passive Thrust Oscillation Mitigation for the CEV Crew Pallet System

    Sammons, Matthew; Powell, Cory; Pellicciotti, Joseph; Buehrle, Ralph; Johnson, Keith

    2012-01-01

    The Crew Exploration Vehicle (CEV) was intended to be the next-generation human spacecraft for the Constellation Program. The CEV Isolator Strut mechanism was designed to mitigate loads imparted to the CEV crew caused by the Thrust Oscillation (TO) phenomenon of the proposed Ares I Launch Vehicle (LV). The Isolator Strut was also designed to be compatible with Launch Abort (LA) contingencies and landing scenarios. Prototype struts were designed, built, and tested in component, sub-system, and system-level testing. The design of the strut, the results of the tests, and the conclusions and lessons learned from the program will be explored in this paper.

  13. Trajectory control with continuous thrust applied to a rendezvous maneuver

    A rendezvous mission can be divided into the following phases: launch, phasing, far range rendezvous, close range rendezvous and mating (docking or berthing). This paper aims to present a close range rendezvous with closed loop controlled straight line trajectory. The approaching is executed on V-bar axis. A PID controller and continuous thrust are used to eliminate the residual errors in the trajectory. A comparative study about the linear and nonlinear dynamics is performed and the results showed that the linear equations become inaccurate insofar as the chaser moves away from the target

  14. Design of high power electromechanical actuator for thrust vector control

    Cowan, J. R.; Myers, W. N.

    1991-01-01

    NASA-Marshall has undertaken the development of electromechanical actuators (EMAs) for thrust vector control (TVC) augmentation system implementation. The TVC EMA presented has as its major components two three-phase brushless dc motors, a two-pass gear-reduction system, and a roller screw for rotary-to-linear motion conversion. System control is furnished by a solid-state electronic controller and power supply; a pair of resolvers deliver position feedback to the controller, such that precise positioning is achieved. Peformance comparisons have been conducted between the EMA and comparable-performance hydraulic systems applicable to TVCs.

  15. Evolving Stress State and Deformation Mechanism in the Himalayan Foreland Fold-and-Thrust Belt, Northern Pakistan

    Ahmad, I.; Dasti, N.

    2010-12-01

    Crustal deformation along with shortening due to northward under-thrusting of the Indian plate beneath the Eurasian plate continues to create active tectonic features on the northern fringes of the Indian craton since major collision began in the Eocene. Here the study provides insights on the evolving stress state and deformation mechanism of the Salt Range and Potwar area of Northern Pakistan. This part of Himalayan foreland fold-and-thrust-belt has severe history of deformation during 5.1 Ma and 2 Ma. This foreland area lies between Main Boundary Thrust (MBT) in the north, Himalayan Frontal Thrust (HFT) in the south and Jhelum fault of sinistral nature in the east & Kalabagh fault of dextral nature in the west. An integrated data from seismic reflection profiles and drilling logs reveal that the subsurface deformation encompasses pop-ups, imbricates, duplexes with in-sequence and out-of-sequence thrusting. It also depicts that intensity of deformation increases from the northern margin of Soan geosyncline towards north due to lacking of evaporites while in the south it decreases due to gradual increase in salt thickness. Surface geologic mapping glimpses a series of thrust sheets and anticlines trending ENE-SWS in the eastern and central part of the study area; whereas in the western part, the trend is almost E-W. This variation in the trend of structures is the result of counter clock rotational behaviour (~10°deviation from north to the west) of north-western part of the Indian lithospheric plate. Current outcrop-scale natural fracture data collected from selected anticlinal structures of the study area is presented to manifest the stress evolution and deformation styles under the established tectonic framework. Collected data is analysed for the evaluation of tectonic stress direction and deformation mechanism. The genetic arrangement and types of fractures observed in the study area indicate that the whole area is under compression. The data also testify

  16. Quantifying Early Miocene in-sequence and out-of-sequence thrusting at the Alpine-Carpathian junction

    Beidinger, A.; Decker, K.

    2014-03-01

    A detailed reconstruction of late Oligocene and Early Miocene thrusting at the leading edge of the East Alpine fold-thrust belt is achieved from well data, seismic, and interpretative cross sections. Data are used for constraining the paleogeographic positions of the Alpine thrusts, quantifying in-sequence/out-of-sequence thrust distances, assessing the timing of thrust propagation from structurally higher units into more external ones, and estimating thrust velocities. Results are depicted in five palinspastic maps for time slices between ~26 Ma and ~16 Ma. The termination of foreland-propagating thrusting at the Alpine front is apparently controlled by the subcrop topography of the European basement, which includes a major recess in the east leading to a diachronic along-strike termination of foreland-propagating thrusting with younger thrust ages and higher in-sequence thrust distances in the east. Early locking of foreland-propagating thrusting in the west causes prominent out-of-sequence thrusts which add to the in-sequence thrust distances there. Continuing consecutive detachment of foreland units in the east occurs at rather fast propagation velocities with time intervals between foreland-thrust-propagations ranging between 0.1 and 0.7 Ma. The resulting increase of in-sequence thrust distances from west to east is balanced by out-of-sequence thrusts in the west. The total amount of late Oligocene to Early Miocene thrusting is quantified with a minimum of 51 km. Average thrust velocities range between 4.6 and 5.2 mm/yr. This rate refers to the movement of the basal thrust at the leading edge of the fold-thrust belt, which occurs contemporaneous with the eastward lateral extrusion of the Eastern Alps in the hinterland.

  17. An Autonomous Onboard Targeting Algorithm Using Finite Thrust Maneuvers

    Scarritt, Sara K.; Marchand, Belinda G.; Brown, Aaron J.; Tracy, William H.; Weeks, Michael W.

    2010-01-01

    In earlier investigations, the adaptation and implementation of a modified two-level corrections (or targeting) process as the onboard targeting algorithm for the Trans-Earth Injection phase of Orion is presented. The objective of that targeting algorithm is to generate the times of ignition and magnitudes of the required maneuvers such that the desired state at entry interface is achieved. In an actual onboard flight software implementation, these times of ignition and maneuvers are relayed onto Flight Control for command and execution. Although this process works well when the burn durations or burn arcs are small, this might not be the case during a contingency situation when lower thrust engines are employed to perform the maneuvers. Therefore, a new model for the two-level corrections process is formulated here to accommodate finite burn arcs. This paper presents the development and formulation of the finite burn two-level corrector, used as an onboard targeting algorithm for the Trans-Earth Injection phase of Orion. A performance comparison between the impulsive and finite burn models is also presented. The present formulation ensures all entry constraints are met, without violating the available fuel budget, while allowing for low-thrust scenarios with long burn durations.

  18. Design and test of electromechanical actuators for thrust vector control

    Cowan, J. R.; Weir, Rae Ann

    1993-01-01

    New control mechanisms technologies are currently being explored to provide alternatives to hydraulic thrust vector control (TVC) actuation systems. For many years engineers have been encouraging the investigation of electromechanical actuators (EMA) to take the place of hydraulics for spacecraft control/gimballing systems. The rationale is to deliver a lighter, cleaner, safer, more easily maintained, as well as energy efficient space vehicle. In light of this continued concern to improve the TVC system, the Propulsion Laboratory at the NASA George C. Marshall Space Flight Center (MSFC) is involved in a program to develop electromechanical actuators for the purpose of testing and TVC system implementation. Through this effort, an electromechanical thrust vector control actuator has been designed and assembled. The design consists of the following major components: Two three-phase brushless dc motors, a two pass gear reduction system, and a roller screw, which converts rotational input into linear output. System control is provided by a solid-state electronic controller and power supply. A pair of resolvers and associated electronics deliver position feedback to the controller such that precise positioning is achieved. Testing and evaluation is currently in progress. Goals focus on performance comparisons between EMA's and similar hydraulic systems.

  19. Status and tendencies for low to medium thrust propulsion systems

    Hopmann, Helmut; Pitt, Richard; Schwende, Manfred; Zewen, Helmut

    The previous use of space liquid propulsion systems in the low thrust range (up to approx. 400 N) has been almost entirely devoted to providing the attitude and orbit control of satellites, including apogee injection. The use of hydrazine peroxide gave way to monopropellant hydrazine in the late sixties whilst the advent of bipropellant systems came with the launch of the Symphonie satellite in 1974. In general, these propulsion systems, together with their feed system components, are more or less standardized with only minor changes required in terms of configuration or propellant mass (tank size) for each satellite. The future, however, promises much greater diversification for the low and medium thrust propulsion systems with increasing technical demands on the engines and their associated equipment. Space Station programs, like Columbus with its in-orbit servicing requirement, will require longer life components and increased modularity whilst manned launch vehicles, such as Ariane 5 with Hermes or Space Planes such as Sänger or Hotol, will demand much higher safety and reliability requirements together with maximum reusability.

  20. Resin Transfer Moulding Of An Engine Thrust Frame Cone Cap

    Brodsjo, Anders; Fatemi, Javad; de Vries, Henri

    2012-07-01

    For the Ariane 5 Midlife Evolution, a new Engine Thrust Frame for the upper stage is being developed. Part of this Engine Thrust Frame is the so-called Cone Cap, which closes the inverted cone shape of the structure. This part is highly loaded, as it transfers all the loads from the engines to the cone shape, and includes the hinge points for the mechanism that steer the engines. Besides strength to cope with the loads, stiffness is a very important design parameter. A composite design of this structure has been developed, which is approximately 15 kg’s lighter than the aluminium structure. To manufacture such a part in composites is challenging, because of the complexity of the shape and large laminate thickness. Due to these requirements, Resin Transfer Moulding has been selected as manufacturing method, which allows this highly integrated structure to be made in one step. As part of this project, a quarter segment of the full-scale design has been manufactured. From the design model, a detailed design for the dry fibre preform has been made using advanced composite laminate software tools. This preform was placed inside a heated, double sided tool and injected with the resin.

  1. A robotic platform for studying sea lion thrust production

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

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

  2. Design and test of electromechanical actuators for thrust vector control

    Cowan, J. R.; Weir, Rae Ann

    1993-05-01

    New control mechanisms technologies are currently being explored to provide alternatives to hydraulic thrust vector control (TVC) actuation systems. For many years engineers have been encouraging the investigation of electromechanical actuators (EMA) to take the place of hydraulics for spacecraft control/gimballing systems. The rationale is to deliver a lighter, cleaner, safer, more easily maintained, as well as energy efficient space vehicle. In light of this continued concern to improve the TVC system, the Propulsion Laboratory at the NASA George C. Marshall Space Flight Center (MSFC) is involved in a program to develop electromechanical actuators for the purpose of testing and TVC system implementation. Through this effort, an electromechanical thrust vector control actuator has been designed and assembled. The design consists of the following major components: Two three-phase brushless dc motors, a two pass gear reduction system, and a roller screw, which converts rotational input into linear output. System control is provided by a solid-state electronic controller and power supply. A pair of resolvers and associated electronics deliver position feedback to the controller such that precise positioning is achieved. Testing and evaluation is currently in progress. Goals focus on performance comparisons between EMA's and similar hydraulic systems.

  3. Thrust producing mechanisms in ray-inspired underwater vehicle propulsion

    Geng Liu

    2015-01-01

    Full Text Available This paper describes a computational study of the hydrodynamics of a ray-inspired underwater vehicle conducted concurrently with experimental measurements. High-resolution stereo-videos of the vehicle’s fin motions during steady swimming are obtained and used as a foundation for developing a high fidelity geometrical model of the oscillatory fin. A Cartesian grid based immersed boundary solver is used to examine the flow fields produced due to these complex artificial pectoral fin kinematics. Simulations are carried out at a smaller Reynolds number in order to examine the hydrodynamic performance and understand the resultant wake topology. Results show that the vehicle’s fins experience large spanwise inflexion of the distal part as well as moderate chordwise pitching during the oscillatory motion. Most thrust force is generated by the distal part of the fin, and it is highly correlated with the spanwise inflexion. Two sets of inter-connected vortex rings are observed in the wake right behind each fin. Those vortex rings induce strong backward flow jets which are mainly responsible for the fin thrust generation.

  4. Contouring Control for a CNC Milling Machine Driven by Direct thrust Controlled Linear Induction Motors

    Khaled N. Faris; Hala S. Khalil,; Khaled S. Sakkoury

    2015-01-01

    According to various advantages of linear induction motor (LIM), such as high starting thrust force, high speed operation and reduction of mechanical losses, more applications have utilized this type of motors. Direct Thrust Control (DTC) technique is considered as one of the most efficient techniques that can be used for LIM. DTC is preferable to give a fast and good dynamic thrust response. So, to improve the accuracy and robustness of contouring control for CNC mach...

  5. Seismic and magnetic images at the Sumatra-Andaman mega thrust subduction zone earthquake (MW 9.3)

    Complete text of publication follows. The December 26, 2004 Sumatra-Andaman earthquake (MW 9.3), the fourth largest event (M≥9.0) in the world during the last 100 years, occurred by thrust faulting at the subducting India plate. The main shock rupture, ∼1200 km long and ∼200 km wide, propagated from north of Sumatra to Andaman-Nicobar Islands; the slow rupture generated Tsunami which killed about 300,000 people. The mega thrust event was followed by an intense aftershock activity spreading over the rupture area. Seismotectonic processes suggest predominant thrust faulting in the fore arc region, and normal/strike slip faulting in the back arc region, consistent with the regional tectonics. Pre- and Post- earthquake marine geophysics surveys show changes in magnetic (100 - 150 nT) as well as in bathymetry (15-25 m) of the ocean floor. The transient geomagnetic filed variations and the seismic tomography results are reviewed to shed a new light on the regional seismic structures of the Andaman-Sumatra subduction zone. The sediment filled fore arc basin as well as the volcanic arc is well reflected as high conducting and low seismic velocity zone compared to outer non-volcanic island arc. The high conductivity and low seismic velocity are attributed to conducting magma materials and or trapped fluid due to subduction process, and the images revealed the subducting tectonic features.

  6. Finite-thrust optimization of interplanetary transfers of space vehicle with bimodal nuclear thermal propulsion

    Kharytonov, Oleksii M.; Kiforenko, Boris M.

    2011-08-01

    The nuclear thermal rocket (NTR) propulsion is one of the leading promising technologies for primary space propulsion for manned exploration of the solar system due to its high specific impulse capability and sufficiently high thrust-to-weight ratio. Another benefit of NTR is its possible bimodal design, when nuclear reactor is used for generation of a jet thrust in a high-thrust mode and (with an appropriate power conversion system) as a source of electric power to supply the payload and the electric engines in a low-thrust mode. The model of the NTR thrust control was developed considering high-thrust NTR as a propulsion system of limited power and exhaust velocity. For the proposed model the control of the thrust value is accomplished by the regulation of reactor thermal power and propellant mass flow rate. The problem of joint optimization of the combination of high- and low-thrust arcs and the parameters of bimodal NTR (BNTR) propulsion system is considered for the interplanetary transfers. The interplanetary trajectory of the space vehicle is formed by the high-thrust NTR burns, which define planet-centric maneuvers and by the low-thrust heliocentric arcs where the nuclear electric propulsion (NEP) is used. The high-thrust arcs are analyzed using finite-thrust approach. The motion of the corresponding dynamical system is realized in three phase spaces concerning the departure planet-centric maneuver by means of high-thrust NTR propulsion, the low-thrust NEP heliocentric maneuver and the approach high-thrust NTR planet-centric maneuver. The phase coordinates are related at the time instants of the change of the phase spaces due to the relations between the space vehicle masses. The optimal control analysis is performed using Pontryagin's maximum principle. The numerical results are analyzed for Earth-Mars "sprint" transfer. The optimal values of the parameters that define the masses of NTR and NEP subsystems have been evaluated. It is shown that the low-thrust

  7. Experimental study of a low-thrust measurement system for thruster ground tests

    Gong, Jingsong; Hou, Lingyun; Zhao, Wenhua

    2014-03-01

    The development of thrusters used for the control of position and orbit of micro-satellites requires thrust stands that can measure low thrust. A new method to measure low thrust is presented, and the measuring device is described. The test results show that the thrust range is up to 1000 mN, the measurement error of the device is lower than ±1% of full scale, and the drift of the zero offset is less than ±1% of full scale. Its response rise time is less than 15 ms. It is employed to measure the working process of a model chemical thruster with repeatability.

  8. Seafloor expression and shallow structure of a fold-and-thrust system, Isfjorden, west Spitsbergen

    Maria Blinova

    2012-09-01

    Full Text Available A detailed map of the structure of the west Spitsbergen fold-and-thrust belt in the Isfjorden area, Spitsbergen, is presented. The map was constructed from a dense grid of two-dimensional multichannel reflection seismic and bathymetric data. Joint interpretation of two data sets allowed a comparison of tectonic structures detected along the uppermost parts of the seismic sections and those reflected in the morphology of the seafloor. Three major, predominantly north-west–south-east striking faults were identified. The westernmost fault (T1 is a hinterland-directed (most likely out of sequence thrust, while the central and easternmost faults (T2 and T3 are foreland-directed (in-sequence thrusts. The thrusts divide Isfjorden into three subareas. Subarea 1 is bounded by thrust faults T1 and T2 and comprises Tertiary rocks surrounded by Jurassic–Cretaceous strata. The structural signature of Subarea 1 is that of a system of hinterland- and foreland-directed thrust faults, resulting in a seafloor relief characterized by parallel ridges and troughs. Subarea 2 is limited by thrust faults T2 and T3 and shows Jurassic–Cretaceous outcrops on the seafloor. Subarea 3 is situated east of the main thrust fault T3 and mainly involves outcrops of Triassic–Jurassic rocks. Together, Subareas 2 and 3 are dominated by foreland-directed, north-west–south-east and NNW–SSE-striking thrusts that are hardly detectable in bathymetric data.

  9. Structural style of the Okcheon fold-thrust belt in the Taebaeksan Zone, Korea

    Jang, Yirang; Kwon, Sanghoon; Yi, Keewook

    2015-06-01

    Structural interpretation of the distinct map pattern defined by highly connected thrust traces in the map view of the Taebaeksan Zone provides insight into the structural style of the northeastern Okcheon Belt. The map pattern can generally be explained by either a folded imbricate fan or a hinterland dipping duplex. The same geometry could also be formed by a complex combination of major imbricate thrusts and their connecting splays, having the structural architecture of a typical fold-thrust belt. However, a folded imbricate fan model is not adequate to explain the absence of late Paleozoic to early Mesozoic strata (i.e. the Pyeongan Supergroup) between two major thrusts (viz. the Pyeongchang and Machari thrusts) in this area. This result further suggests that the Yeongwol area, the western part of the Taebaeksan Zone, is a duplex that corresponds to a more internal and deeper hinterland part of the fold-thrust belt, while the imbricate thrusts with low connectivity in the Taebaek area, the eastern part of the Taebaeksan Zone, indicate a more external and shallower foreland portion of the belt. In addition, cross-cutting relations and newly obtained sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon ages from a cross-cutting dike and syntectonic sedimentary rocks suggest limited thrust reactivation after the early Jurassic and early Tertiary, respectively. In spite of this, the original geometry of the fold-thrust wedge in the Taebaeksan Zone remained well preserved.

  10. Thrust Analysis of a Fish Robot Actuated by Piezoceramic Composite Actuators

    Quang Sang Nguyen; Hoon Cheol Park; Doyoung Byun

    2011-01-01

    In this work, a three-dimensional (3D) Computational Fluid Dynamics (CFD) model was built to simulate the tail fin motion of a fish robot actuated by a piezoceramic composite actuator, and to determine the maximum thrust tail-beat frequency. A simulation of the tail fin at a tail-beat frequency was performed to confirm measured thrust data from a previous study. The computed and measured thrusts were in good agreement. A series of thrust simulations were conducted for various tail-beat frequencies to confirm the maximum thrust frequency that was obtained from thrust measurements in the previous study. The largest thrust was calculated at a tail-beat frequency of 3.7 Hz and vortices around the tail were fully separated. The calculated maximum thrust tail-beat frequency was in good agreement with the measured frequency. Flow characteristics during tail fin motion were examined to explain why the largest thrust occurred at this particular tail-beat frequency.

  11. Non-cylindrical fold growth in the Zagros fold and thrust belt (Kurdistan, NE-Iraq)

    Bartl, Nikolaus; Bretis, Bernhard; Grasemann, Bernhard; Lockhart, Duncan

    2010-05-01

    The Zagros mountains extends over 1800 km from Kurdistan in N-Iraq to the Strait of Hormuz in Iran and is one of the world most promising regions for the future hydrocarbon exploration. The Zagros Mountains started to form as a result of the collision between the Eurasian and Arabian Plates, whose convergence began in the Late Cretaceous as part of the Alpine-Himalayan orogenic system. Geodetic and seismological data document that both plates are still converging and that the fold and thrust belt of the Zagros is actively growing. Extensive hydrocarbon exploration mainly focuses on the antiforms of this fold and thrust belt and therefore the growth history of the folds is of great importance. This work investigates by means of structural field work and quantitative geomorphological techniques the progressive fold growth of the Permam, Bana Bawi- and Safeen- Anticlines located in the NE of the city of Erbil in the Kurdistan region of Northern Iraq. This part of the Zagros fold and thrust belt belongs to the so-called Simply Folded Belt, which is dominated by gentle to open folding. Faults or fault related folds have only minor importance. The mechanical anisotropy of the formations consisting of a succession of relatively competent (massive dolomite and limestone) and incompetent (claystone and siltstone) sediments essentially controls the deformation pattern with open to gentle parallel folding of the competent layers and flexural flow folding of the incompetent layers. The characteristic wavelength of the fold trains is around 10 km. Due to faster erosion of the softer rock layers in the folded sequence, the more competent lithologies form sharp ridges with steeply sloping sides along the eroded flanks of the anticlines. Using an ASTER digital elevation model in combination with geological field data we quantified 250 drainage basins along the different limbs of the subcylindrical Permam, Bana Bawi- and Safeen- Anticlines. Geomorphological indices of the drainage

  12. Static internal performance of a single-engine onaxisymmetric-nozzle vaned-thrust-reverser design with thrust modulation capabilities

    Leavitt, L. D.; Burley, J. R., II

    1985-01-01

    An investigation has been conducted at wind-off conditions in the stati-test facility of the Langley 16-Foot Transonic Tunnel. The tests were conducted on a single-engine reverser configuration with partial and full reverse-thrust modulation capabilities. The reverser design had four ports with equal areas. These ports were angled outboard 30 deg from the vertical impart of a splay angle to the reverse exhaust flow. This splaying of reverser flow was intended to prevent impingement of exhaust flow on empennage surfaces and to help avoid inlet reingestion of exhaust gas when the reverser is integrated into an actual airplane configuration. External vane boxes were located directly over each of the four ports to provide variation of reverser efflux angle from 140 deg to 26 deg (measured forward from the horizontal reference axis). The reverser model was tested with both a butterfly-type inner door and an internal slider door to provide area control for each individual port. In addition, main nozzle throat area and vector angle were varied to examine various methods of modulating thrust levels. Other model variables included vane box configuration (four or six vanes per box), orientation of external vane boxes with respect to internal port walls (splay angle shims), and vane box sideplates. Nozzle pressure ratio was varied from 2.0 approximately 7.0.

  13. On the Design of Tilting-Pad Thrust Bearings

    Heinrichson, Niels

    2007-01-01

    Pockets are often machined in the surfaces of tilting-pad thrust bearings to allow for hydrostatic jacking in the start-up phase. Pockets and other recesses in the surfaces of bearing pads influence the pressure distribution and thereby the position of the pivot resulting in the most advantageous...... based on the Reynolds equation are used. They include the effects of variations of viscosity with temperature and the deformation of the bearing pads due to pressure and thermal gradients. The models are validated using measurements. Tilting-pad bearings of standard design are studied and the influences...... geometries are given. Parallel-step bearings theoretically have smaller friction coefficients than tilting-pad bearings. A design of a tilting-pad bearing is suggested which combines the benefits of the two types of bearings in a tilting-pad bearing with inlet pockets. This design results in a substantial...

  14. Experimental fatigue life investigation of cylindrical thrust chambers

    Quentmeyer, R. J.

    1977-01-01

    The thrust chambers studied in the investigation have been designed for a possible use in the Space Shuttle main engine. An annular combustion chamber configuration was used, consisting of an annular injector, a liquid hydrogen cooled outer cylinder, which served as the test section, and a contoured water cooled centerbody which formed the throat. Twenty-two cylinders were fabricated by milling cooling channels into liners fabricated from the material to be evaluated. The three materials chosen for the liners include OFHC copper, Amzirc, and NARloy-Z. The cylinders were cyclically tested until failure occurred due to fatigue cracks in the hot-gas-side wall. It was found that cylinders with liners fabricated from NARloy-Z and aged Amzirc had the best cyclic life characteristics.

  15. Data Archive and Portal Thrust Area Strategy Report

    Sivaraman, Chitra; Stephan, Eric G.; Macduff, Matt C.; Hagler, Clay D.

    2014-09-30

    This report describes the Data Archive and Portal (DAP), a key capability of the U.S. Department of Energy's Atmosphere to Electron (A2e) initiative. The DAP Thrust Area Planning Group was organized to develop a plan for deploying this capability. Primarily, the report focuses on a distributed system--a DOE Wind Cloud--that functions as a repository for all A2e data. The Wind Cloud will be accessible via an open, easy-to-navigate user interface that facilitates community data access, interaction, and collaboration. DAP management will work with the community, industry, and international standards bodies to develop standards for wind data and to capture important characteristics of all data in the Wind Cloud.

  16. Thrust Measurements in Ballistic Pendulum Ablative Laser Propulsion Experiments

    This paper describes a setup for thrust measurement in ablative laser propulsion experiments, based on a simple ballistic pendulum associated to an imaging system, which is being assembled at IEAv. A light aluminium pendulum holding samples is placed inside a 100 liters vacuum chamber with two optical windows: the first (in ZnSe) for the laser beam and the second (in fused quartz) for the pendulum visualization. A TEA-CO2 laser beam is focused to the samples providing ablation and transferring linear moment to the pendulum as a whole. A CCD video camera captures the oscillatory movement of the pendulum and the its trajectory is obtained by image processing. By fitting the trajectory of the pendulum to a dumped sinusoidal curve is possible to obtain the amplitude of the movement which is directly related to the momentum transfered to the sample

  17. Thrusts and Prospects on Understanding and Predicting Asian Monsoon Climate

    WANG Bin

    2008-01-01

    Development of monsoon climate prediction through integrated research efforts to improve our understanding of monsoon variability and predictability is a primary goal of the Asian Monsoon Years (2007-2011) and International Monsoon Study under the leadership of the World Climate Research Programme.The present paper reviews recent progress in Asian monsoon research focusing on (1) understanding and modeling of the monsoon variability, (2) determining the sources and limits of predictability, and (3) assessing the current status of climate prediction, with emphasis on the weekly to interannual time scales. Particular attention is paid to identify scientific issues and thrust areas, as well as potential directions to move forward in an attempt to stimulate future research to advance our understanding of monsoon climate dynamics and improve our capability to forecast Asian monsoon climate variation.

  18. Mechanical properties of foliated cataclasites from the Nobeoka thrust

    Kitajima, Hiroko; Takahashi, Miki; Kimura, Gaku; Yamaguchi, Asuka; Saito, Saneatsu; Hamahashi, Mari; Fukuchi, Rina; Kameda, Jun; Hamada, Yohei; Fujimoto, Koichiro; Hashimoto, Yoshitaka; Kitamura, Yujin; Hina, Shoko; Eida, Mio

    2014-05-01

    Understanding the mechanics of plate boundary earthquakes requires a sound investigation of the deformation style and mechanical behavior not only within plate boundary faults but also in the surrounding rocks. It is critical to quantify the strain accumulation and accommodation in the entire subduction systems. Recent studies suggest that heterogeneous deformation and strain distribution in mélanges observed in many ancient accretionary prism outcrops are related to slow slip events and low frequency earthquakes [Fagereng and Sibson, 2010; Kitamura and Kimura, 2011]. However, there are few experimental studies to describe mechanical properties of mélanges and foliated cataclasites. Here, we report on triaxial deformation experiments on foliated cataclasites from the footwall of the Nobeoka thrust, Japan. The Nobeoka thrust, which is exhumated in Kyushu, southwest Japan, is considered as one of the ancient out-of-sequence faults. The Nobeoka thrust fault core, hanging wall, and foot wall rocks were recently cored and logged in a vertical borehole as a NOBELL project [Hamahashi et al., in press]. The Nobeoka thrust is recovered at 41.3 m from the ground. The hanging wall (0-41.3 m coring interval) is composed of the Kitagawa Group of phyllite of alternating beds of sandstone and shale, while the footwall (41.3-255 m) is composed of the Hyuga Group of foliated cataclasite consisting of scaly shale, tuffacious shale, sandstone, and acidic tuff. For deformation experiments, we used foliated catacalsite core samples, which are in better quality and less weathered than outcrop samples. Cylindrical samples with a diameter of 20 mm and a length of 30 mm were subsampled from the cores. The cylindrical specimen were deformed at an axial displacement rate of 0.05-0.5 μm/s, corresponding to strain rates of 1.6 ×10-6-1.6 ×10-5 s-1, and at a temperature of 250 ° C and an effective pressure (Pe) of 120 MPa (confining pressure of 200 MPa and pore pressure of 80 MPa) or 20

  19. Foil Gas Thrust Bearings for High-Speed Turbomachinery

    Edmonds, Brian; DellaCorte, Christopher; Dykas, Brian

    2010-01-01

    A methodology has been developed for the design and construction of simple foil thrust bearings intended for parametric performance testing and low marginal costs, supporting continued development of oil-free turbomachinery. A bearing backing plate is first machined and surface-ground to produce flat and parallel faces. Partial-arc slots needed to retain the foil components are then machined into the plate by wire electrical discharge machining. Slot thicknesses achievable by a single wire pass are appropriate to accommodate the practical range of foil thicknesses, leaving a small clearance in this hinged joint to permit limited motion. The backing plate is constructed from a nickel-based superalloy (Inconel 718) to allow heat treatment of the entire assembled bearing, as well as to permit hightemperature operation. However, other dimensionally stable materials, such as precipitation-hardened stainless steel, can also be used for this component depending on application. The top and bump foil blanks are cut from stacks of annealed Inconel X-750 foil by the same EDM process. The bump foil has several azimuthal slits separating it into five individual bump strips. This configuration allows for variable bump spacing, which helps to accommodate the effects of the varying surface velocity, thermal crowning, centrifugal dishing, and misalignment. Rectangular tabs on the foil blanks fit into the backing plate slots. For this application, a rather traditional set of conventionally machined dies is selected, and bump foil blanks are pressed into the dies for forming. This arrangement produces a set of bump foil dies for foil thrust bearings that provide for relatively inexpensive fabrication of various bump configurations, and employing methods and features from the public domain.

  20. Study of blind thrust faults underlying Tokyo and Osaka urban areas using a combination of high-resolution seismic reflection profiling and continuous coring

    K. Miura

    2003-06-01

    Full Text Available We acquired high-resolution seismic reflection profiles and continuously cored boreholes to evaluate active flexures produced by major blind thrust fault systems within two densely populated Neogene-Quaternary sedimentary basins in Japan: the Fukaya Fault System near Tokyo in the Kanto Basin and the Uemachi Fault System in the Osaka Basin. The high-resolution seismic reflection survey made clear the length, geometry and growth history of fault-related folds, or flexures formed above the two blind thrusts. Continuously cored boreholes linked with high-resolution seismic profiles enabled us to estimate the uplift rate as defined by shallow stratigraphic horizons and constrain the age of the most recent growth of the flexures during earthquakes on the Fukaya and Uemachi fault systems. Even with the high quality of the data we collected, it is still not possible to exactly constrain the age of the most recent blind thrust earthquake recorded by flexure of these fault-related folds. Data presented in this paper form the basis for future efforts aimed at mechanical and kinematic models for fault growth to evaluate the activity of blind thrusts underlying urban areas.

  1. Drainage migration and out of sequence thrusting in Bhalukpong, Western Arunachal Himalaya, India

    De Sarkar, Sharmistha; Mathew, George; Pande, Kanchan; Phukon, Parag; Singhvi, Ashok Kumar

    2014-11-01

    In the foreland regions of the Western Arunachal Himalaya (WAH), geological studies along the Kameng river (between Tipi village and the Himalayan Frontal Thrust (HFT)) reveal four levels of unpaired terraces and a paired terrace. In WAH, wrench deformation of HFT zone resulted in a SE propagation of the Balipara anticline and it is suggested that the Mikir high basement controls its orientation. Ages of terrace surfaces from Siwaliks suggest that since the Late Pleistocene, Kameng River migrated at a rate varying between ∼7.5 cm/yr in upper reaches and ∼13.5 cm/yr towards northeast due to HFT related uplift. In the Brahmaputra plains, luminescence ages of abandoned paleochannel deposits suggest eastward shifting of the Kameng river at an average rate of ∼1 m/yr. Field evidences between Bhalukpong and Tipi villages show Pliocene strath and Quaternary terrace surfaces, displaced by faults that do not correspond to the mapped faults in the foreland region. We interpret them as out-of-sequence thrusts (OOSTs). This is the first such report of OOST in the NE Himalaya. Presence of active OOST is inferred by similar age (∼1 ka) and differing incision rates of the surface of same terrace (T2b) in adjacent locations. This suggests that OOSTs in the western Arunachal Siwalik are <1 ka. Average slip rate and horizontal shortening rate on OOST during the Holocene, are calculated as ∼12 mm/yr and 7 mm/yr respectively. Thus any estimation of Holocene shortening in the Siwalik therefore, needs to incorporate slip along the OOSTs given that it accommodates a significant amount of N-S compression of the Himalayan fold-and-thrust belt. The reason for OOST in the WAH Siwalik foreland is discussed in terms of the critical wedge dynamics arising from erosion via tectonics-climate interaction. We estimate a minimum slip rate of Siwalik as ∼27 mm/yr during the Holocene and suggest acceleration in shortening rates east of Bhutan.

  2. Kinematic Analysis of Fold-Thrust-Belt Using Integrated Analogue Sandbox Modeling and 3D Palinspatic Reconstructions in Babar-Selaru Area, Banda Sea Region, Indonesia

    Sapiie, Benyamin; Hadiana, Meli; Kurniawan, Ade; Daniel, Dicky; Danio, Harya; Fujimoto, Masamichi; Ohara, Michio; Alam Perdana, Lisnanda; Saputra, Afif

    2016-04-01

    particularly important to have best modeling results. The complexities of the thrust loading and flexure mechanism, causing Babar Selaru area has unique style of normal faults which are simultaneously active with thrust-faulting process.

  3. Tongue Strength: Its Relationship to Tongue Thrusting, Open-Bite, and Articulatory Proficiency.

    Dworkin, James P.; Culatta, Richard A.

    1980-01-01

    No significant differences in tongue strength were found between any of the three groups of 7- to 16-year old children: normal speaking with anterior tongue thrusting during swallow and open bite malocclusion, frontal lisping with anterior tongue thrusting during swallow and open bite malocclusion, and normal controls. (Author/DLS)

  4. The presence of thrust-block naled after a major surge event: Kuannersuit Glacier, West Greenland

    Yde, Jacob C.; Knudsen, N. Tvis; Larsen, Nicolaj K.; Kronborg, Christian; Nielsen, Ole B.; Heinemeier, Jan; Olsen, Jesper

    Thrust-block naled in front of Kuannersuit Glacier, West Greenland, appears to have formed during the termination of a terrestrial surge event by a combination of enhanced winter runoff, rapid advance of the glacier terminus, and proglacial stress release by thrusting and stacking of naled blocks. This process is equivalent to the formation of thrust-block moraines. The thrust-block naled consists of at least seven thrust sheets, which are characterized by stratified ice with beds composed of a lower debris-rich lamina, an intermediate dispersed lamina and a top clean-ice lamina, and underlain by frozen outwash deposits. The thrust-block naled differs from basal stratified ice in the absence of internal deformation structures, a relatively low debris concentration, a clay-rich particle-size distribution and a preferential sorting of lighter minerals. The oxygen isotope composition of the thrust-block naled is indistinguishable from δ18O values from meteoric glacier ice and bulk meltwater, but different from basal stratified ice facies. The d-δD relationship indicates that thrust-block naled has been formed by freezing of successive thin layers of bulk waters with variable isotopic composition, whereas basal stratified ice has developed in a subglacial environment with regelation. This work shows that the association between proglacial naled and rapidly advancing glaciers may have significant consequences for the proglacial geomorphology and the interpretation of basal ice layers.

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

    Li, Jing

    2016-07-01

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

  6. The In-Space Propulsion Technology Project Low-Thrust Trajectory Tool Suite

    Dankanich, John W.

    2008-01-01

    The ISPT project released its low-thrust trajectory tool suite in March of 2006. The LTTT suite tools range in capabilities, but represent the state-of-the art in NASA low-thrust trajectory optimization tools. The tools have all received considerable updates following the initial release, and they are available through their respective development centers or the ISPT project website.

  7. Centrifuge modelling of fold—thrust structures in a tripartite stratigraphic succession

    Dixon, John M.; Tirrul, Rein

    Analog models measuring 127 × 76 mm in plan were deformed at 2500-4000 g in a centrifuge. Scaled stratigraphic sequences were constructed of anisotropic multilayers with individual layers of Plasticine and silicone putty as thin as 40 μm. The plasticine—silicone putty multilayers are analogs for interbedded competent carbonates and clastics, and incompetent pelites, given the model ratios of acceleration, 2500 g; length, 5 × 10 -6; specific gravity, 0.6; time 10 -10. Modelling of fold—thrust tectonics emphasizes the influence of stratigraphic succession on structural evolution. The models are constructed with a tripartite stratigraphic succession comprising basal and upper, well-laminated and incompetent units, and a middle, somewhat more isotropic and competent unit. The models deform by three mechanisms: layer-parallel shortening, folding and thrust faulting. They reproduce a number of fold—thrust relationships that have been observed in nature. Folds are typically periclinal, in en échelon arrays. Folds and thrusts are arcuate in plan, reflecting differential shortening. Fold attitudes grade from upright at high levels to overturned at deeper levels within a structural panel, reflecting drag against the basal décollement; fold axial surfaces and thrust faults are listric. While competent units may be offset by localized displacement on thrust faults, the discrete faults may die out both upwards and downwards into regions of ductile strain in less-competent units. Thrust faults appear to follow staircase trajectories through the strata, transecting incompetent units at shallow angles to bedding and competent units at steeper angles. However, the apparent staircase pattern results from propagation of a fault along a relatively straight trajectory through previously-folded strata. Foreland-verging thrusts are more common than back thrusts; the latter have steeper dips. The models suggest a mechanism of thrust-ramp nucleation following detachment folding

  8. Distribution of natural radionuclide along Main Central Thrust in Garhwal Himalaya

    R.C. Ramola

    2014-10-01

    Full Text Available Study of natural radionuclide is important to assess the radiation level in a particular area. Radionuclide present in earth's crust is different for different geological areas because of the variety of soil and rocks present in a particular area. In present study, the estimation of natural radionuclides have been carried out along the Main Central Thrust (MCT in Uttarkashi, Budhakedar, Ukhimath and Healang regions of Garhwal Himalaya, India. The large variations in the radionuclide distribution have been estimated along the Main Central Thrust. The 226Ra, 232Th and 40K contents in MCT area varies from 8 ± 1 Bq.kg−1 to 285 ± 28 Bq.kg−1 with an average of 64 Bq.kg−1, 7 ± 1 Bq.kg−1 to 136 ± 15 Bq.kg−1 with an average 69 Bq.kg−1 and 115 ± 18 Bq.kg−1 to 1588 ± 162 Bq.kg−1 with an average 792 Bq.kg−1, respectively. The radon exhalation rate and radon concentration in the soil of study area varies from 2.20 × 10−5 Bq.kg−1h−1 to 3.2 × 10−5 Bq.kg−1h−1 and 287 Bq/m3 to 417 Bq/m3, respectively. It was observed that the distribution of natural radionuclide in the soil of study area is not uniform and concentrated along geological active region. These values of radionuclide and radon mass exhalation rate may be used as baseline data for further study in the area.

  9. Design and Optimization of Low-thrust Orbit Transfers Using Q-law and Evolutionary Algorithms

    Lee, Seungwon; vonAllmen, Paul; Fink, Wolfgang; Petropoulos, Anastassios; Terrile, Richard

    2005-01-01

    Future space missions will depend more on low-thrust propulsion (such as ion engines) thanks to its high specific impulse. Yet, the design of low-thrust trajectories is complex and challenging. Third-body perturbations often dominate the thrust, and a significant change to the orbit requires a long duration of thrust. In order to guide the early design phases, we have developed an efficient and efficacious method to obtain approximate propellant and flight-time requirements (i.e., the Pareto front) for orbit transfers. A search for the Pareto-optimal trajectories is done in two levels: optimal thrust angles and locations are determined by Q-law, while the Q-law is optimized with two evolutionary algorithms: a genetic algorithm and a simulated-annealing-related algorithm. The examples considered are several types of orbit transfers around the Earth and the asteroid Vesta.

  10. Two-DOF precision platform for spacecraft thrust vector control: control strategies and simulations

    Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

    2004-07-01

    This paper presents control strategies and simulations of a two-DOF precision platform as an adaptive thruster mount structure with precision positioning and active vibration suppression capabilities for thrust vector control of space satellites. First, the configuration of the two-DOF precision platform is introduced, which is an intelligent tripod with two in-plane rotational degrees of freedom for the top device-plate. Precision positioning of this platform is achieved using active members that extend or contract to tilt the top device-plate where the thruster is mounted. Kinematic analysis of the platform is then presented and followed by two control strategies; namely local control strategy and global control strategy. In the local control strategy, the motion of each active member is controlled locally according to the kinematical feature of the platform and the local sensor information to achieve the desired tilt of the top device-plate. In the global control strategy, the motion of each active member is adjusted according to the system level information from a tilt sensor. Fuzzy logic control is employed and the two control strategies are simulated and compared.

  11. Tectonomorphic evolution of the Eastern Cordillera fold-thrust belt, Colombia: New insights based on apatite and zircon (U-Th)/He thermochronometers

    Ghorbal, B.; Stockli, D. F.; Mora, A.; Horton, B. K.; Blanco, V.; Sanchez, N.

    2010-12-01

    along both sides of the orogen in the latest Miocene to early Pliocene, with recent to active deformation again concentrated along the frontal-most faults of the EC. These detailed new apatite and zircon (U-Th)/He thermochronometric data elucidate the progressive deformation, thermal history, and along-long strike variation (Mora et al., 2010) of the fold-thrust belt in the EC of Colombia and provide important new insights into the complex interplay between hydrocarbon maturation and temporal and kinematic evolution of the frontal fold-thrust belt. References [1] Mora, A., M. Parra, M. R. Strecker, A. Kammer, C. Dimaté, and F. Rodriguez, 2006, Cenozoic contractional reactivation of Mesozoic extensional structures in the Eastern Cordillera of Colombia: Tectonics, v. 25, TC2010. [2] Mora, A., Horton, B.K., Mesa, A., Rubiano, J., Ketcham, R.A., Parra, M., Blanco, V., Garcia, D. and D.F. Stockli, 2010, Cenozoic deformation patterns in the Eastern Cordillera, Colombia: Inferences from fission track results and structural relationships. AAPG Bulletin, in press.

  12. Lithological and structural investigations of the Finero back thrust

    Palzer, M.; Österle, J.; Klötzli, U.

    2012-04-01

    complex". New lithological and structural investigations show, that the former assumption of an Alpine back thrust south of the peridotite body of Finero has to be questioned. Field work and petrography was focused on lithological boundaries, high-T shear zones and the distinction of "internal gabbro" and "external gabbro". Our findings reveal distinct discrepancies to older mapping and interpretations. It can be shown, that the contacts between "external gabbro" and hornblende peridotite are high-temperature features and structurally far more complicate than previously supposed which makes greenschist facies Alpine back thrusting most unlikely. The contacts almost certainly are magmatic or at least formed at mantle temperatures. They are thus pre-Alpine in age. Alternatively to the back thrust model, we present a model of a folded multi-layered peridotite body which seems to be inter fingered with the "external gabbro". Our findings definitely corroborate the possibility that the "internal gabbro", the hornblende peridotite and the "external gabbro" form a single magmatic series.

  13. Hydrodynamic optimization of trust ring pump and lubricating oil system for large hydroelectric units thrust bearing

    Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions form thrust bearing and operation conditions of hydro turbine generator unit. Because the oil circulating and cooling system with thrust-ring- pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump, additionally, the head and discharge are varying with the operation conditions of hydro-generator unit and characteristic of the oil circulating and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulating and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization of both the oil circulating and cooling system and thrust-ring-pump is purposed in this paper. Firstly, the head and discharge required at different conditions are decided by 1D flow numerical simulation of the oil circulating and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and discharge from the simulation. Thirdly, the flow passage geometry matching optimization between holes inside the thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulating and cooling system are collaborative hydrodynamic optimized with predicted head- discharge curve and the efficiency-discharge curve of thrust-ring-pump. The presented methodology has

  14. Puente Hills blind-thrust system, Los Angeles, California

    Shaw, J.H.; Plesch, A.; Dolan, J.F.; Pratt, T.L.; Fiore, P.

    2002-01-01

    We describe the three-dimensional geometry and Quaternary slip history of the Puente Hills blind-thrust system (PHT) using seismic reflection profiles, petroleum well data, and precisely located seismicity. The PHT generated the 1987 Whittier Narrows (moment magnitude [Mw] 6.0) earthquake and extends for more than 40 km along strike beneath the northern Los Angeles basin. The PHT comprises three, north-dipping ramp segments that are overlain by contractional fault-related folds. Based on an analysis of these folds, we produce Quaternary slip profiles along each ramp segment. The fault geometry and slip patterns indicate that segments of the PHT are related by soft-linkage boundaries, where the fault ramps are en echelon and displacements are gradually transferred from one segment to the next. Average Quaternary slip rates on the ramp segments range from 0.44 to 1.7 mm/yr, with preferred rates between 0.62 and 1.28 mm/yr. Using empirical relations among rupture area, magnitude, and coseismic displacement, we estimate the magnitude and frequency of single (Mw 6.5-6.6) and multisegment (Mw 7.1) rupture scenarios for the PHT.

  15. Dielectric barrier discharge control and thrust enhancement by diode surface

    Starikovskiy, Andrey; Post, Martiqua; Tkach, Nickolas; Miles, Richard; PU Team

    2013-09-01

    The problem of the charge removal is very simple: we need a surface which will conduct the current in one direction and will have high resistance in another to avoid the leakage during the forward discharge development. Lateral diode string structures were designed and successfully manufactured on a 3-inch 4H-SiC semi-insulating wafer. The experiments with direct thrust measurements at low pressure conditions were performed as well as experiments of jet formation at pressure P = 1 atm. It was shown that the plasma conductivity is limiting the charge transfer through the surface. The minimal pulse width value could be estimated as a plasma recombination time. The surface becomes effective suppressor for the reverse breakdown when the conductivity of plasma layer is small enough with compare to the surface conductivity. It means that the reverse breakdown with nanosecond-range delay removes efficiently all surface charges. Effective flow acceleration using diode surface is possible with long pulses with allow full plasma recombination between leading and trailing pulse fronts.

  16. Pressure thrust and pressure shock arrestor (mixer-diffusor device)

    A mixer-diffusor device for use in nuclear reactors to control the heat and pressure energy resulting from an accident is attached to the end of a hollow conduit from which a gaseous medium such as steam is to be expelled under pressure. The end of the hollow conduit is submerged under the surface of a body of liquid such as water. The mixer-diffusor comprises a conical baffle having an apex extending into the open end of the conduit. A skirt member is positioned around the end of the conduit so than an annular opening is formed between the wall of the conduit and one edge of the skirt member. The skirt member is tapered outwardly at essentially the same angle as the taper of the conical baffle. When the gaseous medium is expelled from the end of the conduit, the gaseous medium flows against and over the conical baffle thereby reducing the thrust forces of the conduit. As the gaseous medium passes the edge of the end of the conduit, the gaseous medium tends to suck the liquid through the annular opening. The liquid is then mixed with the gaseous medium causing the gaseous medium to form a plurality of small bubbles which are expelled from the opening between the skirt and the conical member. In this manner, the gaseous medium is substantially mixed and diffused with the liquid. (auth)

  17. SOURCE TERM TARGETED THRUST FY 2005 NEW START PROJECTS

    NA

    2005-10-05

    While a significant amount of work has been devoted to developing thermodynamic data. describing the sorption of radionuclides to iron oxides and other geomedia, little data exist to describe the interaction of key radionuclides found in high-level radioactive waste with the uranium surfaces expected in corroded spent nuclear fuel (SNF) waste packages. Recent work indicates that actinide adsorption to the U(VI) solids expected in the engineered barrier system may play a key role in the reduction of dissolved concentrations of radionuclides such as Np(V). However, little is known about the mechanism(s) of adsorption, nor are the thermodynamic data available to represent the phenomenon in predictive modeling codes. Unfortunately, this situation makes it difficult to consider actinide adsorption to the U(VI) silicates in either geochemical or performance assessment (PA) predictions. The primary goal in the Source Term Targeted Thrust area is to ''study processes that control radionuclide release from the waste form''. Knowledge of adsorption of actinides to U(VI) silicate solids its and parameterization in geochemical models will be an important step towards this goal.

  18. Viscid/inviscid interaction analysis of thrust augmenting ejectors

    Bevilacqua, P. M.; Dejoode, A. D.

    1979-01-01

    A method was developed for calculating the static performance of thrust augmenting ejectors by matching a viscous solution for the flow through the ejector to an inviscid solution for the flow outside the ejector. A two dimensional analysis utilizing a turbulence kinetic energy model is used to calculate the rate of entrainment by the jets. Vortex panel methods are then used with the requirement that the ejector shroud must be a streamline of the flow induced by the jets to determine the strength of circulation generated around the shroud. In effect, the ejector shroud is considered to be flying in the velocity field of the jets. The solution is converged by iterating between the rate of entrainment and the strength of the circulation. This approach offers the advantage of including external influences on the flow through the ejector. Comparisons with data are presented for an ejector having a single central nozzle and Coanda jet on the walls. The accuracy of the matched solution is found to be especially sensitive to the jet flap effect of the flow just downstream of the ejector exit.

  19. Upstream blockage effect on the thrust force of a marine hydrokinetic device

    Soliani, Giulio; Beninati, Maria Laura; Krane, Michael; Fontaine, Arnold

    2013-11-01

    The study evaluates the interaction of two model marine devices axially arranged one in front of the other, in a tandem configuration. Particular focus is given to the change that occurs in the thrust of the downstream marine hydrokinetic (MHK) device when the spatial arrangement of the two elements is varied. At critical spacing there is no thrust generation. The study is motivated by the need to predict the thrust behavior of MHK devices and determine the minimum separation distance to avoid the no thrust condition. The downstream element is a two-bladed, horizontal axis turbine, while the upstream blockage is a perforated disk with similar geometric properties intended to approximate the wake of the MHK device. Testing is conducted in the flume facility at Bucknell University. Experiments are performed for a fixed range of spacing between the perforated disk and the turbine. For each separation distance, the span-wise velocity profile upstream and downstream of the turbine is measured, as well as the device's rotational speed. The turbine's thrust coefficient is calculated. Plots of the thrust coefficient as a function of spacing depict the minimum separation distance to avoid the no thrust condition.

  20. Mylonitic volcanics near Puging, Upper Siang district, Arunachal Pradesh: Evidence of oblique-slip thrusting

    T K Goswami; P Bhattacharyya; D Bezbaruah

    2016-08-01

    The Abor volcanics of the continental flood basalt affinity are extensively exposed in different parts of the Siang valley. These are associated with Yinkiong Group of rocks of Paleocene–Eocene age and represent syn-sedimentary volcanism in a rift setting. Subsequent folding and thrusting of the Siyom and Rikor sequences above the Yinkiong Group of rocks represent changes from syn-to-post collisionalbrittle-ductile tectonic episodes. Mylonitic Abor volcanics in the thrust contacts are studied at several locations in the north and south of Puging in the Siang valley. Both the Abor volcanics and associated Rikor and Yinkiong Group of rocks preserve meso to micro-scale fabric asymmetries indicating that the thrust contacts are shear zones of brittle-ductile nature containing mylonitic textures of high shear strain.Two distinct hitherto unrecognised shear zones in the north and south of Puging are named as North Puging Shear Zone (NPSZ) and South Puging Shear Zone (SPSZ). The kinematic indicators along the thrust contact indicate oblique slip thrusting of the Rikor and Siyom thrust sheets above the Yinkiong Group of rocks. This paper provides field evidence proving that the compression due the Burmese plate made oblique slip thrusting and zones of mylonitised volcanics possible and associated metasediments were formed. The kinematic indicators in the NPSZ and SPSZ respectively indicate top-to-SSE and top-to-NNW sense of shears.

  1. Co-seismic ruptures of the 12 May 2008, Ms 8.0 Wenchuan earthquake, Sichuan: East-west crustal shortening on oblique, parallel thrusts along the eastern edge of Tibet

    Liu-Zeng, J.; Zhang, Z.; Wen, L.; Tapponnier, P.; Sun, Jielun; Xing, X.; Hu, G.; Xu, Q.; Zeng, L.; Ding, L.; Ji, C.; Hudnut, K.W.; van der Woerd, J.

    2009-01-01

    The Ms 8.0, Wenchuan earthquake, which devastated the mountainous western rim of the Sichuan basin in central China, produced a surface rupture over 200??km-long with oblique thrust/dextral slip and maximum scarp heights of ~ 10??m. It thus ranks as one of the world's largest continental mega-thrust events in the last 150??yrs. Field investigation shows clear surface breaks along two of the main branches of the NE-trending Longmen Shan thrust fault system. The principal rupture, on the NW-dipping Beichuan fault, displays nearly equal amounts of thrust and right-lateral slip. Basin-ward of this rupture, another continuous surface break is observed for over 70??km on the parallel, more shallowly NW-dipping Pengguan fault. Slip on this latter fault was pure thrusting, with a maximum scarp height of ~ 3.5??m. This is one of the very few reported instances of crustal-scale co-seismic slip partitioning on parallel thrusts. This out-of-sequence event, with distributed surface breaks on crustal mega-thrusts, highlights regional, ~ EW-directed, present day crustal shortening oblique to the Longmen Shan margin of Tibet. The long rupture and large offsets with strong horizontal shortening that characterize the Wenchuan earthquake herald a re-evaluation of tectonic models anticipating little or no active shortening of the upper crust along this edge of the plateau, and require a re-assessment of seismic hazard along potentially under-rated active faults across the densely populated western Sichuan basin and mountains. ?? 2009 Elsevier B.V.

  2. Thrust estimator design based on least squares support vector regression machine

    ZHAO Yong-ping; SUN Jian-guo

    2010-01-01

    In order to realize direct thrust control instead of traditional sensor-based control for nero-engines,it is indispensable to design a thrust estimator with high accuracy,so a scheme for thrust estimator design based on the least square support vector regression machine is proposed to solve this problem.Furthermore,numerical simulations confirm the effectiveness of our presented scheme.During the process of estimator design,a wrap per criterion that can not only reduce the computational complexity but also enhance the generalization performance is proposed to select variables as input variables for estimator.

  3. Is tongue thrust that develops during orthodontic treatment an unrecognized potential road block?

    Chawla H

    2006-06-01

    Full Text Available The role of tongue thrust has often been suspected, long debated and largely dispelled as a primary etiological factor of malocclusion. However, tongue thrust may contribute to poor occlusal intercuspation both during and after treatment. A tongue thrust may also develop during orthodontic mechanotherapy as a result of the transient creation of intra and interarch spaces and this little recognized phenomenon was found to occur in many randomly followed cases. In many instances, this seemingly adaptive and secondary response of the tongue posture and function may persist and thereafter impede the resolution of intra and interarch problems.

  4. Seismicity and velocity structures along the south-Alpine thrust front of the Venetian Alps (NE-Italy)

    Anselmi, M.; Govoni, A.; De Gori, P.; Chiarabba, C.

    2011-12-01

    In this paper we show the seismicity and velocity structure of a segment of the Alpine retro-belt front along the continental collision margin of the Venetian Alps (NE Italy). Our goal is to gain insight on the buried structures and deep fault geometry in a "silent" area, i.e., an area with poor instrumental seismicity but high potential for future earthquakes, as indicated by historical earthquakes (1695 Me = 6.7 Asolo and 1936 Ms = 5.8 Bosco del Cansiglio). Local earthquakes recorded by a dense temporary seismic network are used to compute 3-D Vp and Vp/Vs tomographic images, yielding well resolved images of the upper crust underneath the south-Alpine front. We show the presence of two main distinct high Vp S-verging thrust units, the innermost coincides with the piedmont hill and the outermost is buried under a thick pile of sediments in the Po plain. Background seismicity and Vp/Vs anomalies, interpreted as cracked fluid-filled volumes, suggest that the NE portion of the outermost blind thrust and its oblique/lateral ramps may be a zone of high fluid pressure prone to future earthquakes. Three-dimensional focal mechanisms show compressive and transpressive solutions, in agreement with the tectonic setting, stress field maps and geodetic observations. The bulk of the microseismicity is clustered in two different areas, both in correspondence of inherited lateral ramps of the thrust system. Tomographic images highlight the influence of the paleogeographic setting in the tectonic style and seismic activity of the region.

  5. Seismic variability of subduction thrust faults: Insights from laboratory models

    Corbi, F.; Funiciello, F.; Faccenna, C.; Ranalli, G.; Heuret, A.

    2011-06-01

    Laboratory models are realized to investigate the role of interface roughness, driving rate, and pressure on friction dynamics. The setup consists of a gelatin block driven at constant velocity over sand paper. The interface roughness is quantified in terms of amplitude and wavelength of protrusions, jointly expressed by a reference roughness parameter obtained by their product. Frictional behavior shows a systematic dependence on system parameters. Both stick slip and stable sliding occur, depending on driving rate and interface roughness. Stress drop and frequency of slip episodes vary directly and inversely, respectively, with the reference roughness parameter, reflecting the fundamental role for the amplitude of protrusions. An increase in pressure tends to favor stick slip. Static friction is a steeply decreasing function of the reference roughness parameter. The velocity strengthening/weakening parameter in the state- and rate-dependent dynamic friction law becomes negative for specific values of the reference roughness parameter which are intermediate with respect to the explored range. Despite the simplifications of the adopted setup, which does not address the problem of off-fault fracturing, a comparison of the experimental results with the depth distribution of seismic energy release along subduction thrust faults leads to the hypothesis that their behavior is primarily controlled by the depth- and time-dependent distribution of protrusions. A rough subduction fault at shallow depths, unable to produce significant seismicity because of low lithostatic pressure, evolves into a moderately rough, velocity-weakening fault at intermediate depths. The magnitude of events in this range is calibrated by the interplay between surface roughness and subduction rate. At larger depths, the roughness further decreases and stable sliding becomes gradually more predominant. Thus, although interplate seismicity is ultimately controlled by tectonic parameters (velocity of

  6. Effectiveness of Nitrous Oxide as a Liquid Injection Thrust Vector Control Fluid Project

    National Aeronautics and Space Administration — Nitrous Oxide is proposed as an energetic liquid injection thrust vector control fluid for vehicle attitude control during dynamic vehicle maneuvers. Pulled from...

  7. rf power system for thrust measurements of a helicon plasma source

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

    2010-07-01

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

  8. Precise timing of the Early Paleozoic metamorphism and thrust deformation in the Eastern Kunlun Orogen

    2002-01-01

    In Dulan County, Qinghai Province NW China, the arc volcanic sequences in the northern side of the Central Fault of the East Kunlun were metamorphosed progressively from upper greenschist facies in the south to epidote-amphibolite facies in the north. High-angle thrust deforma-tion was developed synchronously with the peak metamor-phim and superimposed with later low-angle striking-slip deformation. Zircon U-Pb dating yields a concordant age of (448 ± 4) Ma for the metavolcanics. Syn-kinematic horn-blende and muscovite separated from the high-angle thrust-ing belt give 40Ar-39Ar plateau age of (427 ± 4) Ma and 408 Ma, respectively. These results precisely constrain the timing of the closure of early Paleozoic volcanic basin (Proto-Tethys) over the eastern portion of the East Kunlun Orogen, and the thrust tectonic slice had a cool rate of ca. 9℃/Ma.

  9. A Simple Method to Measure Nematodes' Propulsive Thrust and the Nematode Ratchet.

    Bau, Haim; Yuan, Jinzhou; Raizen, David

    2015-11-01

    Since the propulsive thrust of micro organisms provides a more sensitive indicator of the animal's health and response to drugs than motility, a simple, high throughput, direct measurement of the thrust is desired. Taking advantage of the nematode C. elegans being heavier than water, we devised a simple method to determine the propulsive thrust of the animals by monitoring their velocity when swimming along an inclined plane. We find that the swimming velocity is a linear function of the sin of the inclination angle. This method allows us to determine, among other things, the animas' propulsive thrust as a function of genotype, drugs, and age. Furthermore, taking advantage of the animals' inability to swim over a stiff incline, we constructed a sawteeth ratchet-like track that restricts the animals to swim in a predetermined direction. This research was supported, in part, by NIH NIA Grant 5R03AG042690-02.

  10. rf power system for thrust measurements of a helicon plasma source

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