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1

Hydrostatic thrust bearing for storage pumps  

Energy Technology Data Exchange (ETDEWEB)

The hydrostatic axial thrust bearing for the storage pump at San Fiorano, Italy, represents the first full-scale application of this type of bearing to large machines. Operational experience has confirmed that these thrust bearings are suitable for hydraulic machines with high axial forces, and detailed measurements have shown that the bearing behaves in accordance with the design calculations. The total losses are now only about 6.3% of the total losses of the original oil-lubricated hydrodynamic thrust bearings. This reduction corresponds to a savings of about 1.1 MW or an overall efficiency increase of about 1%.

Christ, A.; Peron, M.

1980-01-01

2

Combination radial and thrust magnetic bearing  

Science.gov (United States)

A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

Blumenstock, Kenneth A. (Inventor)

2002-01-01

3

Design and analysis of thrust active magnetic bearing  

Science.gov (United States)

This paper deals with the design and analysis of thrust active magnetic bearing (AMB). Using the analytical solutions for thrust, resistance, and inductance obtained from equivalent magnetic circuits method, we determine initial design parameters such as the size of magnetic circuit, coil diameter, and the number of turns by investigating the variation of thrust according to design parameters. Then, using nonlinear finite element analysis, a detailed design considering saturation is performed in order to meet required thrust under restricted conditions. Finally, by confirming that the design result is shown in good agreement with experimental results, the validity of design procedures for thrust AMB used in this paper is proved. In particular, the dynamic test results of the thrust AMB are also given to confirm the validity of the design.

Jang, Seok-Myeong; Lee, Un-Ho; Choi, Jang-Young; Hong, Jung-Pyo

2008-04-01

4

Foil Gas Thrust Bearings for High-Speed Turbomachinery  

Science.gov (United States)

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.

Edmonds, Brian; DellaCorte, Christopher; Dykas, Brian

2010-01-01

5

Performance of Gas-Lubricated Nonconforming Pivoted-Pad Journal Bearings and a Flexibly Mounted Spiral-Groove Thrust Bearing.  

Science.gov (United States)

A test program was conducted to determine the performance characteristics of gas-lubricated nonconforming pivoted-pad journal bearings and a spiral-groove thrust bearing designed for the Brayton cycle rotating unit (BRU). Hydrostatic, hybrid (simultaneous...

L. W. Ream

1973-01-01

6

Elasto-Hydrodynamic Lubrication Effect in Thrust-Slide Bearings of Scroll Compressors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents the concept of the Elasto-Hydrodynamic Lubrication (EHL) effect for the thrust slide-bearings in scroll compressors, which accounts for the superior lubrication characteristics of these bearings. The thrust plate undergoes elastic deformation due to axial loading, resulting in the formation of a fluid wedge between the orbiting and fixed thrust plates, a region with very high induced oil film pressure which, in turn, accounts for the remarkably good lubrication characteris...

2012-01-01

7

Ontario Hydro`s Sir Adam Beck Pump Generating Station : thrust bearing and runner servomotor rehabilitation  

Energy Technology Data Exchange (ETDEWEB)

A study was conducted to examine the reasons for the recurring failure of generator thrust bearings at Ontario Hydro`s Sir Adam Beck Pump Generating Station (Niagara Falls) comprised of six 25 MW Deriaz turbines. The possible causes for the thrust bearing failures were listed and commented upon. The suspected causes include: (1) marginal bearing capacity, (2) shoes not flat, (3) sub standard oil, (4) dirt in bearing, (5) bearing cooling problems. To solve the problem, extra precaution was taken in the assembly of the bearing parts and extra capacity was added to the oil lift system. Following implementation of these measures, the unit has been operating smoothly for 3 years. 3 tabs., 4 figs.

Barbour, J.; Garro, A. [Ontario Hydro, Toronto, ON (Canada)

1998-12-01

8

A rotary microactuator supported on encapsulated microball bearings using an electro-pneumatic thrust balance  

International Nuclear Information System (INIS)

The development of a rotary microactuator supported on encapsulated microball bearings and driven by electro-pneumatic actuation is reported. The encapsulated bearing provides full support to an encased rotor, while an electro-pneumatic thrust balance is used to minimize rotor normal load. By minimizing normal load, bearing friction is reduced leading to increased speed and performance. Experimental results show that the microactuator is capable of repeatable operation and continuous 360° motion at speeds of 5–2000 rpm. This is the first demonstration of a ball bearing supported electrostatic microactuator with a fully encased rotor, capable of direct mechanical attachment or reliable interaction with external media

2009-09-01

9

Bulk-Flow Analysis of Hybrid Thrust Bearings for Advanced Cryogenic Turbopumps  

Science.gov (United States)

A bulk-flow analysis and computer program for prediction of the static load performance and dynamic force coefficients of angled injection, orifice-compensated hydrostatic/hydrodynamic thrust bearings have been completed. The product of the research is an efficient computational tool for the design of high-speed thrust bearings for cryogenic fluid turbopumps. The study addresses the needs of a growing technology that requires of reliable fluid film bearings to provide the maximum operating life with optimum controllable rotordynamic characteristics at the lowest cost. The motion of a cryogenic fluid on the thin film lands of a thrust bearing is governed by a set of bulk-flow mass and momentum conservation and energy transport equations. Mass flow conservation and a simple model for momentum transport within the hydrostatic bearing recesses are also accounted for. The bulk-flow model includes flow turbulence with fluid inertia advection, Coriolis and centrifugal acceleration effects on the bearing recesses and film lands. The cryogenic fluid properties are obtained from realistic thermophysical equations of state. Turbulent bulk-flow shear parameters are based on Hirs' model with Moody's friction factor equations allowing a simple simulation for machined bearing surface roughness. A perturbation analysis leads to zeroth-order nonlinear equations governing the fluid flow for the thrust bearing operating at a static equilibrium position, and first-order linear equations describing the perturbed fluid flow for small amplitude shaft motions in the axial direction. Numerical solution to the zeroth-order flow field equations renders the bearing flow rate, thrust load, drag torque and power dissipation. Solution to the first-order equations determines the axial stiffness, damping and inertia force coefficients. The computational method uses well established algorithms and generic subprograms available from prior developments. The Fortran9O computer program hydrothrust runs on a Windows 95/NT personal computer. The program, help files and examples are licensed by Texas A&M University Technology License Office. The study of the static and dynamic performance of two hydrostatic/hydrodynamic bearings demonstrates the importance of centrifugal and advection fluid inertia effects for operation at high rotational speeds. The first example considers a conceptual hydrostatic thrust bearing for an advanced liquid hydrogen turbopump operating at 170,000 rpm. The large axial stiffness and damping coefficients of the bearing should provide accurate control and axial positioning of the turbopump and also allow for unshrouded impellers, therefore increasing the overall pump efficiency. The second bearing uses a refrigerant R134a, and its application in oil-free air conditioning compressors is of great technological importance and commercial value. The computed predictions reveal that the LH2 bearing load capacity and flow rate increase with the recess pressure (i.e. increasing orifice diameters). The bearing axial stiffness has a maximum for a recess pressure rati of approx. 0.55. while the axial damping coefficient decreases as the recess pressure ratio increases. The computer results from three flow models are compared. These models are a) inertialess, b) fluid inertia at recess edges only, and c) full fluid inertia at both recess edges and film lands. The full inertia model shows the lowest flow rates, axial load capacity and stiffness coefficient but on the other hand renders the largest damping coefficients and inertia coefficients. The most important findings are related to the reduction of the outflow through the inner radius and the appearance of subambient pressures. The performance of the refrigerant hybrid thrust bearing is evaluated at two operating speeds and pressure drops. The computed results are presented in dimensionless form to evidence consistent trends in the bearing performance characteristics. As the applied axial load increases, the bearing film thickness and flow rate decrease while the recess pressure increases. The a

SanAndres, Luis

1998-01-01

10

Optimization of residual heat removal pump axial thrust and axial bearing  

Energy Technology Data Exchange (ETDEWEB)

The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.

Schubert, F.

1996-12-01

11

Detecting thrust bearing failure within a screw compressor  

International Nuclear Information System (INIS)

A 3 1/2 mile ring of over 1000 superconducting magnets are needed to focus and drive the world's highest energy particle smasher. 24 Refrigerators supply liquid helium to the magnets; 34 high pressure oil flooded screw compressors supply 285 psig helium gas to the refrigerators. The 400 h.p. screws are reliable machines that use 45 gallons of oil per minute to seal and lubricate the rotors, lubricate the bearings, and remove the heat of compression. These machines are spaced out in seven buildings over four miles. A minimum of 28 machines must be operating at all times. A contingent of operators start, stop, and monitor any machine from a distant control room. The 34 compressors have an average of 32,000 hours; 9 machines have over 40,000 hours; the highest is 55,000 hours

1994-01-01

12

Fault architecture and deformation mechanisms in exhumed analogues of seismogenic carbonate-bearing thrusts  

Science.gov (United States)

Faults in carbonates are well known sources of upper crustal seismicity throughout the world. In the outer sector of the Northern Apennines, ancient carbonate-bearing thrusts are exposed at the surface and represent analogues of structures generating seismicity at depth. We describe the geometry, internal structure and deformation mechanisms of three large-displacement thrusts from the km scale to the microscale. Fault architecture and deformation mechanisms are all influenced by the lithology of faulted rocks. Where thrusts cut across bedded or marly limestones, fault zones are thick (tens of metres) and display foliated rocks (S-CC' tectonites and/or YPR cataclasites) characterized by intense pressure-solution deformation. In massive limestones, faulting occurs in localized, narrow zones that exhibit abundant brittle deformation. A general model for a heterogeneous, carbonate-bearing thrust is proposed and discussed. Fault structure, affected by stratigraphic heterogeneity and inherited structures, influences the location of geometrical asperities and fault strain rates. The presence of clay minerals and the strain rate experienced by fault rocks modulate the shifting from cataclasis-dominated towards pressure-solution-dominated deformation. Resulting structural heterogeneity of these faults may mirror their mechanical and seismic behaviour: we suggest that seismic asperities are located at the boundaries of massive limestones in narrow zones of localized slip whereas weak shear zones constitute slowly slipping portions of the fault, reflecting other types of "aseismic" behaviour.

Tesei, Telemaco; Collettini, Cristiano; Viti, Cecilia; Barchi, Massimiliano R.

2013-10-01

13

The Hydro-Support: An Elasto-Hydrostatic Thrust Bearing with Mixed Lubrication:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The "classic" solution for the support of a translating lockgate, the wheelonrail support, has relatively high construction as well as inspection and maintenance costs. An alternative support which has previously been developed for use in the Prins WillemAlexander lock is the socalled "hydrosupport", a hydrostatic thrust bearing that slides on an elastic track and is connected to the lockgate by an elastic support. After a runningin period, this support shows low friction....

Ostayen, R. A. J.

2002-01-01

14

Exhumed analogues of seismically active carbonate-bearing thrusts: fault architecture and deformation mechanisms  

Science.gov (United States)

In May 2012 a M = 5.9 earthquake followed by a long aftershock sequence struck the Northern Italy. The sequence occurred at 4-10 km depth within the active front of Northern Apennines Prism and the major events nucleate within, or propagate through, a thick sequence of carbonates. In an inner sector of the Northern Apennines, ancient carbonate-bearing thrusts exposed at the surface, represent exhumed analogues of structures generating seismicity in the active front. Here we document fault architecture and deformation mechanisms of three regional carbonate bearing thrusts with displacement of several kilometers and exhumation in the range of 1-4 km. Fault zone structure and deformation mechanisms are controlled by the lithology of the faulted rocks. In layered limestones and marly-limestones the fault zone is up to 200 m thick and is characterized by intense pressure solution. In massive limestones the deformation generally occurs along thin and sharp slip planes that are in contact with fault portions affected by either cataclasis or pressure solution. SEM and TEM observations show that pressure solution surfaces, made of smectite lamellae, with time tend to form an interconnected network affected by frictional sliding. Sharp slipping planes along massive limestones show localization along Y shear planes that separate an extremely comminuted cataclasites from an almost undeformed protolith. The comparison of the three shear zones depicts a fault zone structure extremely heterogeneous as the result of protolith lithology, geometrical complexities and the presence of inherited structures. We observe the competition between brittle (cataclasis, distributed frictional sliding along phyllosilicates and extremely localized slip within carbonates) and pressure solution processes, that suggest a multi-mode of slip behaviour. Extreme localization along carbonate-bearing Y shear planes is our favorite fault zone feature representing past seismic ruptures along the studied thrust faults.

Tesei, T.; Collettini, C.; Viti, C.; Barchi, M. R.

2012-12-01

15

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

Science.gov (United States)

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 designed with the objective of keeping the trajectories on the compressor characteristic curve, the compressor performance and efficiency are no longer sacrificed by excessive recycling to achieve stability. In order to explore these conjectures experimentally, a high speed centrifugal compressor test facility with active magnetic bearings is developed. The test facility can be used for implementing the proposed surge control method and also for assessing the impeller and bearing loads at off-design conditions. This data can then be used to verify and refine analytical models used in compressor design. (Abstract shortened by UMI.)

Sanadgol, Dorsa

16

Rheodynamic Lubrication of an Externally Pressured Thrust Bearing Using Herschel-Bulkley Fluid with Sinusoidal Injection  

Directory of Open Access Journals (Sweden)

Full Text Available Lubricants with variable viscosity are assuming greater importance for its application in polymer industry, thermal reactors and in biomechanics. With the bearing operations in machines being subject to high speeds, loads, increasing mechanical shearing forces and continually increasing pressure, there has been an increasing interest to use non-Newtonian fluids characterized by a yield value. Some of them, which fit into this class, are Bingham, Casson and Herchel-Bulkley models. In the present work, the problem of an externally pressurized thrust bearing lubricated with Herschel-Bulkley fluid under the sinusoidal flow rate has been investigated. Herschel-Bulkley fluids are characterized by a yield value, which leads to the formation of rigid core in the flow region. The shape and extent of the core has been determined numerically for various values of the Herschel-Bulkley number, power-law index, amplitude of sinusoidal fluid film and time. Numerical solutions have been obtained for the bearing performances such as pressure distribution and load capacity for different values of the Herschel-Bulkley number, power-law index, amplitude of sinusoidal fluid film and time. The effects of sinusoidal injection of the lubricant and the non-Newtonian characteristics on the bearing performances have been discussed.

I.J. Amalraj

2012-01-01

17

Numerical modelling of the flow in the annular multi-recess hydrostatic thrust bearing using CFD methods  

Directory of Open Access Journals (Sweden)

Full Text Available The current research of hydrostatic bearings and hydrostatic slide-ways is far from being over. The topic is constantly evolving, creating new geometries of the sliding bearings, developing new types of friction materials and lubricants. The control elements of hydraulic mechanisms that serve to regulation of the hydrostatic bearings tipping are still in progress. Almost every application has different requirements for the bearings, whether in terms of loading capacity, speed rotation, and also the price. All these aspects should be included in the design of hydrostatic thrust bearings. Thanks to great advances in the development of computer technology and software for numerical modelling, we can simulate real movement of viscous fluids. To create a numerical model of hydrostatic thrust bearing, Ansys Fluent 14.0 software package has been applied. The article describes the basic methods of numerical modelling of the given problem and evaluates the pressure field and the loading capacity of annular multi-recess hydrostatic thrust bearing and its dependence on the change in static pressure.

Drbáková S.

2013-04-01

18

Numerical modelling of the flow in the annular multi-recess hydrostatic thrust bearing using CFD methods  

Science.gov (United States)

The current research of hydrostatic bearings and hydrostatic slide-ways is far from being over. The topic is constantly evolving, creating new geometries of the sliding bearings, developing new types of friction materials and lubricants. The control elements of hydraulic mechanisms that serve to regulation of the hydrostatic bearings tipping are still in progress. Almost every application has different requirements for the bearings, whether in terms of loading capacity, speed rotation, and also the price. All these aspects should be included in the design of hydrostatic thrust bearings. Thanks to great advances in the development of computer technology and software for numerical modelling, we can simulate real movement of viscous fluids. To create a numerical model of hydrostatic thrust bearing, Ansys Fluent 14.0 software package has been applied. The article describes the basic methods of numerical modelling of the given problem and evaluates the pressure field and the loading capacity of annular multi-recess hydrostatic thrust bearing and its dependence on the change in static pressure.

Kozdera, M.; Drbáková, S.

2013-04-01

19

The Influence of Injection Pockets on the Performance of Tilting-Pad Thrust Bearings - Part I: Theory  

DEFF Research Database (Denmark)

This is Part I of a two-part series of papers describing the effects of high-pressure injection pockets on the operating conditions of tilting-pad thrust bearings. In Part I a numerical model based on the Reynolds equation is developed extending the threedimensional thermoelastohydrodynamic (TEHD) analysis of tilting-pad thrust bearings to include the effects of high-pressure injection and recesses in the bearing pads. The model is applied to the analysis of an existing bearing of large dimensions and the influence of the pocket is analyzed. In the analysis, the high-pressure oil injection used for hydrostatic jacking is turned off (i.e., only the effect of the pocket is studied). It is shown that a shallow pocket positively influences the performance of the bearing because it has characteristics similar to those of a Rayleigh-step bearing. In Part II of the paper (Heinrichson, N., Fuerst, A., and Santos, I. F., 2007, ASME J. Tribol., 129(4), pp. 904â??912) measurements of pressure profiles and oil film thickness for a test-pad are compared to theoretical results. The analysis of Part II deals both with flow situations, where the high-pressure injection is turned off, as well as with situations where it is turned on for hydrostatic jacking.

Heinrichson, Niels; Santos, Ilmar

2007-01-01

20

The Experimental Analyses of the Effects of the Geometric and Working Parameters on the Circular Hydrostatic Thrust Bearings  

Science.gov (United States)

In this paper, the characteristics of disk-type hydrostatic thrust bearings supporting concentric loads; simulating the major bearing/seal parts of axial piston pumps and motors were investigated. An experimental setup was designed to determine the performance of slippers, which are capable of increasing the efficiency of axial piston pumps and motors, for different conditions. The working parameters and the slipper geometry causing the minimum frictional power loss and leakage oil loss were determined. Since slippers affect the performance of the system considerably, the effects of surface roughnesses on lubrication were studied in slippers with varying hydrostatic bearing areas and surface roughness. The results of the study suggest that the frictional power loss and leakage oil loss were caused by the surface roughness, the relative velocity, the size of the hydrostatic bearing area, supply pressure and capillary tube diameter.

Canbulut, Fazıl

 
 
 
 
21

Inertia Effects in Rheodynamic Lubrication of an Externally Pressurized Thrust Bearing Using Bingham Lubricant with Sinusoidal Injection  

Directory of Open Access Journals (Sweden)

Full Text Available In the present theoretical investigation, the combined effects of fluid inertia forces and sinusoidal injection of the Bingham lubricant, on the performance of an externally pressurized thrust bearing with circular geometry are studied. Using the conventional two-constant Bingham model and by adopting the method of averaging inertia terms, the reduced Navier-Stokes equations are modified and numerical solutions have been obtained for the bearing performances such as the pressure distribution and the load carrying capacity for different values of Bingham number, Reynolds number, time and amplitude. The effects of fluid inertia forces and the non-Newtonian characteristics of the Bingham lubricant on the bearing performances for different sinusoidal conditions are discussed.

I.J. Amalraj

2013-01-01

22

Robust Optimum Design of Thrust Hydrodynamic Bearings for Hard Disk Drives  

Directory of Open Access Journals (Sweden)

Full Text Available This paper describes the robust optimum design which combines the geometrical optimization method proposed by Hashimoto and statistical method. Recently, 2.5? hard disk drives (HDDs are widely used for mobile devices such as laptops, video cameras and car navigation systems. In mobile applications, high durability towards external vibrations and shocks are essentials to the bearings of HDD spindle motor. In addition, the bearing characteristics are influenced by manufacturing error because of small size of the bearings of HDD. In this paper, the geometrical optimization is carried out to maximize the bearing stiffness using sequential quadratic programming to improve vibration characteristics. Additionally, the bearing stiffness is analyzed considering dimensional tolerance of the bearing using statistical method. The dimensional tolerance is assumed to distribute according to the Gaussian distribution, and then the bearing stiffness is estimated by combining the expectation and standard deviation. As a result, in the robust optimum design, new groove geometry of bearing can be obtained in which the bearing stiffness is four times higher than the stiffness of conventional spiral groove bearing. Moreover, the bearing has lower variability compared with the result of optimum design neglecting dimensional tolerance.

Hiromu Hashimoto

2012-10-01

23

Performance of integrated retainer rings in silicon micro-turbines with thrust style micro-ball bearings  

Science.gov (United States)

This work explores the performance of different silicon retainer ring designs when integrated into silicon micro-turbines (SMTs) incorporating thrust style bearings supported on 500 µm diameter steel balls. Experimental performance curves are presented for SMTs with rotor diameters of 5 mm and 10 mm, each with five different retainer designs varying in mechanical rigidity, ball pocket shape and ball complement. It was found that the different retainer designs yielded different performance curves, with the closed pocket designs consistently requiring lower input power for a given rotation speed, and the most rigid retainers giving the best performance overall. Both 5 mm and 10 mm diameter devices have shown repeatable performance at rotation speeds up to and exceeding 20?000 RPM with input power levels below 2 W, and devices were tested for over 2.5 million revolutions without failure. Retainer rings are commonly used in macro-scale bearings to ensure uniform spacing between the rolling elements. The integration of retainers into micro-bearings could lower costs by reducing the number of balls required for stable operation, and also open up the possibility of ‘smart’ bearings with integrated sensors to monitor the bearing status.

Hergert, Robert J.; Hanrahan, Brendan; Ghodssi, Reza; Holmes, Andrew S.

2013-06-01

24

A superconducting thrust-bearing system for an energy storage flywheel  

International Nuclear Information System (INIS)

We have constructed a bearing system for an energy storage flywheel. This bearing system uses a combination of permanent magnets and superconductors in an arrangement commonly termed as an Evershed bearing. In an Evershed system there are in fact two bearings which act in concert. In our system we have one bearing constructed entirely out of permanent magnets acting in attraction. This system bears the weight of the flywheel (43.6 kg) but would not, on its own, be stable. Stability is provided by a superconducting bearing which is formed by the interaction between the magnetic field of a permanent magnet sited on the rotor and superconductors on the stator. This overall arrangement is stable over a range of levitation heights and has been tested at rotation speeds of up to around 12 Hz (the maximum speed is dictated by the drive system not the bearing system). There is a sharp resonance peaking at between 2 and 3 Hz and spin down tests indicate that the equivalent coefficient of friction is of the order of 10-5. The rate of change of velocity is, however, not constant so the drag is clearly not solely frictional. The position of the resonance is dictated by the stiffness of the bearing relative to the mass of the flywheel but the amplitude of the resonance is dictated by the variation in magnitude of the magnetic field of the permanent magnets. Large magnets are (at present) fabricated in sections and this leads to a highly inhomogeneous field. The field has been smoothed by using a combination of iron which acts passively and copper which provides magnetic shielding due to the generation of eddy currents and therefore acts as an 'active' component. Calculations based on the spin down tests indicate that the resultant variation in field is of the order of 3% and measurements are being carried out to confirm this. (author)

2002-05-01

25

Robust Optimum Design of Thrust Hydrodynamic Bearings for Hard Disk Drives  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper describes the robust optimum design which combines the geometrical optimization method proposed by Hashimoto and statistical method. Recently, 2.5? hard disk drives (HDDs) are widely used for mobile devices such as laptops, video cameras and car navigation systems. In mobile applications, high durability towards external vibrations and shocks are essentials to the bearings of HDD spindle motor. In addition, the bearing characteristics are influenced by manufacturing error because...

Hiromu Hashimoto; Yuta Sunami

2012-01-01

26

On the selection of design parameters of the thrust gas bearing with an outside supercharging  

International Nuclear Information System (INIS)

The problems of stability of high-speed rators in gas bearings have been considered. To provide stable operating conditions, the upper limit of the operating speed range of the rotor, supported on unilinear gas bearings with the outside supercharging, should be selected not exceeding 0.7 of the threshold speed of the vortex instability. The investigations of a number of bearings with various radial gaps and elongations show that maximum threshold speeds are reached at dimensionless parameters of supercharging, lambdasub(s)=0.35-0.45. The decrease of parameters lambdasub(s) results in a deterioration of damping properties of the bearing and an increased sensitivity to the operating loss of balance and external excitation. Due to nonlinear properties of the elastic characteristic of the gas layer, the synchronous resonance frequency and the threshold speed in the range of optimal lambdasub(s) substantially depends on the value of disbalance. With the increase in the disbalance from 0.3-0.4 ?m to 7.7 ?m, the threshold speed decreases by 25-30%. The recommended values of the diameter and the number of feeders, of the radial gap, relative elongation and permissible residual nonequilibrium are given

1977-01-01

27

Performance of large-bore tapered-roller bearings under combined radial and thrust load at shaft speeds to 15,000 rpm  

Science.gov (United States)

The performance of 120.65-mm bore tapered roller bearings was investigated at shaft speeds up to 15,000 rpm. Temperature distribution and bearing heat generation were determined as a function of shaft speed, radial and thrust loads, lubricant flow rate, and lubricant inlet temperature. Lubricant was supplied by either jets or by a combination of holes through the cone directly to the cone-rib contact and jets at the roller small-end side. Cone-rib lubrication significantly improved high-speed tapered-roller bearing performance, yielding lower cone-face temperatures and lower power loss and allowing lower lubricant flow rates for a given speed condition. Bearing temperatures increased with increased shaft speed and decreased with increased lubricant flow rate. Bearing power loss increased with increased shaft speed and increased lubricant flow rate.

Parker, R. J.; Signer, H. R.

1977-01-01

28

Measuring axial pump thrust  

Energy Technology Data Exchange (ETDEWEB)

An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices.

Suchoza, Bernard P. (McMurray, PA); Becse, Imre (Washington, PA)

1988-01-01

29

The Development of Open Water-lubricated Polycrystalline Diamond (PCD) Thrust Bearings for Use in Marine Hydrokinetic (MHK) Energy Machines  

Energy Technology Data Exchange (ETDEWEB)

Polycrstalline diamond (PCD) bearings were designed, fabricated and tested for marine-hydro-kinetic (MHK) application. Bearing efficiency and life were evaluated using the US Synthetic bearing test facility. Three iterations of design, build and test were conducted to arrive at the best bearing design. In addition life testing that simulated the starting and stopping and the loading of real MHK applications were performed. Results showed polycrystalline diamond bearings are well suited for MHK applications and that diamond bearing technology is TRL4 ready. Based on life tests results bearing life is estimated to be at least 11.5 years. A calculation method for evaluating the performance of diamond bearings of round geometry was also investigated and developed. Finally, as part of this effort test bearings were supplied free of charge to the University of Alaska for further evaluation. The University of Alaska test program will subject the diamond bearings to sediment laden lubricating fluid.

Cooley, Craig, H.; Khonsari, Michael,, M; Lingwall, Brent

2012-11-28

30

Numerical modelling of the flow in the annular multi-recess hydrostatic thrust bearing using CFD methods  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The current research of hydrostatic bearings and hydrostatic slide-ways is far from being over. The topic is constantly evolving, creating new geometries of the sliding bearings, developing new types of friction materials and lubricants. The control elements of hydraulic mechanisms that serve to regulation of the hydrostatic bearings tipping are still in progress. Almost every application has different requirements for the bearings, whether in terms of loading capacity, speed rotation, and al...

Kozdera M.; Drbáková S.

2013-01-01

31

Bears  

Science.gov (United States)

What are the characteristics of grizzly/brown bears and black bears? As you view the websites, please use this chart to record what you are learning about grizzly bears and black bears. For each bear, you should list 5 characteristics. Grizzly Bear and Black Bear Chart We will first begin by learning about black bears. Please go to these websites to learn some important facts about black bears. Black Bears Facts and Image Black Bear Facts for Kids Now that you have learned ...

Bledsoe, Miss

2011-04-07

32

Bears, Bears, Bears!  

Science.gov (United States)

What are some things you learned about bears? Use these websites to find out about bears: Parts of a Bear Polar Bears Real Story of the Three Bears The truth about bears Brown Bears Now fill in your chart! Bear Fact Sheet Listen to your teacher for further instruction on completing a book about bears! ...

Ms.beason

2011-04-16

33

Influence of hydrostatic pump operation period on performance of a thrust bearing of a 125 MW pump-turbine; Influence de la duree de fonctionnement de la pompe hydrostatique sur les performances d'une butee d'une turbopompe de 125 MW  

Energy Technology Data Exchange (ETDEWEB)

A special instrumented pad was installed at hydrodynamic thrust bearing of 125 MW pump turbine in one of Polish power plants. 'Spring mattress' type thrust bearings of these machines are quite heavily loaded and have caused many problems so far. It was intended to assess bearing present state more thoroughly than with the use of standard monitoring system and to assist in bearing research and development attempts. Instrumentation of the pad comprises 16 thermocouples for measurements of temperature distribution in the pad and 3 proximity probes to evaluate the pad position and film thickness. The pump-turbine with an instrumented bearing was tested at various operating conditions including steady state and transient conditions. One of the examples of the research carried out with the use of the described instrumentation was the research into the influence of hydrostatic jacking pump operation period on bearing performance in transient states which is presented in the paper. The results showed that current practice of pump operation is far from optimum, and that bearing reliability could be improved by changing the current start-up and coasting procedures. The results also showed that pad position during operation is not satisfactory and also some improvement could probably be achieved by rearranging the support of the bearing pad. (authors)

Dabrowski, L.; Wasilczuk, M. [Technical University of Gdansk, Faculty of Mechanical Engineering, Gdansk (Poland)

2004-02-01

34

PPT Thrust Stand  

Science.gov (United States)

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

Haag, Thomas W.

1995-01-01

35

Monte Mountain thrust, additional confirmation of the central Nevada thrust  

Energy Technology Data Exchange (ETDEWEB)

The Monte Mountain thrust, a newly identified thrust exposed in the Timpahute Range, east central Nevada places porous Devonian reservoir rocks over rich Mississippian source rocks at the peak oil generating window. The thrust provides insurmountable evidence of a thrust model that may lead to discovery of giant oil and gas fields along the 400-mi long central Nevada thrust belt. The Timpahute Range lies a little over 50 mi on strike to the south of the prolific Grant Canyon field. Scattered remnants of the north-trending thrust belt are obscured by parallel valleys of Tertiary valley fill and volcanics. The fact that the east-west-trending Timpahute Range could contain exposures of the north-south-trending central Nevada thrust belt attracted them to the range, Familiarity with the stratigraphic section led to the discovery of the thrust. As much as 750 ft of Devonian Guilmette sandstones, in the hanging wall just above the thrust contact have been erroneously mapped as Mississippian Scotty Wash sandstones. These Devonian sandstones could be excellent reservoir rocks. Sandstones in the Guilmette increase in thickness westward. East-vergent thrusting has juxtaposed plates of thicker Guilmette sandstones with plates of thinner sandstones, Reconstruction of Devonian paleogeography provides a clue to the amount of displacement along thrust boundaries.

Chamberlain, A.K. (Cedar Strat, Lakewood, CO (USA)); Chamberlain, R.L. (Anschutz Corp., Denver, CO (USA))

1990-05-01

36

A MICRO TURBINE DEVICE WITH ENHANCED MICRO AIR-BEARINGS  

Digital Repository Infrastructure Vision for European Research (DRIVER)

As part of progress in developing a micro gas turbine engine, this paper presents the design, fabrication and testing of a silicon-based micro turbine device, which is driven by compressed air. To improve its rotational speed and stability, the turbine device has enhanced journal air bearing and thrust air bearings. The thrust air bearings are utilized for supporting the rotor from both its top- and bottom- sides. The top thrust air bearing employs pump-in type spiral grooves, and the bottom ...

Shan, X. -c; Zhang, Qide; Sun, Y. F.; Maeda, R.

2006-01-01

37

Numerical and experimental investigations of micro air bearings for micro systems  

Energy Technology Data Exchange (ETDEWEB)

The paper investigated performance of air bearing system in a micro device. A parametric study is carried out. The dynamic performance of a very short journal bearing (L/D < 0.1) and thrust bearing is studied. The parameters that affect the performance of the air bearing are discussed. The optimum values of the important parameters are explored, and the stability of the thrust bearing is discussed. The prototype and test result are presented.

Zhang Qide [Data Storage Institute, DSI Building (off Kent Ridge Crescent, NUS), Singapore 117608 (Singapore); Shan, X C [Singapore Institute of Manufacturing Technology, 71 Nanyang Drive, Singapore 638075 (Singapore)

2006-04-01

38

Thrust modeling for hypersonic engines  

Science.gov (United States)

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

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

1995-01-01

39

Polar Bears  

Science.gov (United States)

Use the following websites to answer questions about the rapid disappearance of polar bears in the Arctic region. Polar Bear picture Polar Bear Tracker 1: What region in the world has the fewest polar bears? 2: Using the internet as a resource, provide some reasons as to why this region is suffering from the most polar bear differences? Polar Bears Change Diet 1: Why are polar bears having to change their diets? 2: List some other factors (besides diet) in the ...

Thomas, Mr.

2010-09-27

40

Constant Thrust Hybrid Rocket Motor.  

Science.gov (United States)

The constant thrust hybrid rocket motor of this invention is capable of providing operation for at least 50 seconds over a wide temperature range and with minimal variation in chamber pressure. The constant thrust hybrid rocket motor of this invention inc...

A. L. Holzman

1981-01-01

 
 
 
 
41

Low-thrust rocket trajectories  

Energy Technology Data Exchange (ETDEWEB)

The development of low-thrust propulsion systems to complement chemical propulsion systems will greatly enhance the evolution of future space programs. Two advantages of low-thrust rockets are stressed: first, in a strong gravitational field, such as occurs near the Earth, freighter missions with low-thrust engines require one-tenth as much propellant as do chemical engines. Second, in a weak gravitational field, such as occurs in the region between Venus and Mars, low-thrust rockets are faster than chemical rockets with comparable propellant mass. The purpose here is to address the physics of low-thrust trajectories and to interpret the results with two simple models. Analytic analyses are used where possible - otherwise, the results of numerical calculations are presented in graphs. The author has attempted to make this a self-contained report. 57 refs., 10 figs.

Keaton, P.W.

1986-01-01

42

Bearing system  

Energy Technology Data Exchange (ETDEWEB)

A bearing system includes backup bearings for supporting a rotating shaft upon failure of primary bearings. In the preferred embodiment, the backup bearings are rolling element bearings having their rolling elements disposed out of contact with their associated respective inner races during normal functioning of the primary bearings. Displacement detection sensors are provided for detecting displacement of the shaft upon failure of the primary bearings. Upon detection of the failure of the primary bearings, the rolling elements and inner races of the backup bearings are brought into mutual contact by axial displacement of the shaft.

Kapich, Davorin D. (Carlsbad, CA)

1987-01-01

43

Polar Bear Polar Bear  

Science.gov (United States)

In this lesson, students will listen for key details in a nonfiction text about polar bears. They will work at completing a graphic organizer with the teacher to help organize their thinking and understanding of key details about a text. They will also complete an independent assignment where they will draw or write two things that they learned about the topic.

Burgess, Kelly

2012-09-11

44

Pulsed Electric Propulsion Thrust Stand Calibration Method  

Science.gov (United States)

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

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

2011-01-01

45

Cage unbalance and wear in ball bearings  

Energy Technology Data Exchange (ETDEWEB)

The dynamic cage interactions in a high-speed ball bearing are modeled as a function of unbalance. The resulting cage wear rates and overall power loss in the bearing are parametrically evaluated with varying levels of unbalance in the cage. Both outer and inner race guided cages are considered with a combined thrust and rotating radial load on the bearing. Although the level of unbalance, beyond which the cage interactions become excessive, is almost equal for both outer and inner race guided cages, cage guidance on the stationary outer race appears to be somewhat more favorable, both in terms of power loss and cage wear. (orig.).

Gupta, P.K. (PKG, Inc., Clifton Park, NY (USA))

1991-07-05

46

Dry Friction Bearings.  

Science.gov (United States)

Contents: Porous metal ceramic bearings; Mineral ceramic bearings; Self-lubricating pressed wood bearings; Metal materials for special bearings; Operation of rolling surface bearings under dry friction conditions; Rolling surface bearings with solid lubri...

B. D. Voronkov

1970-01-01

47

Weakening inside incipient thrust fault  

Science.gov (United States)

In fold-and-thrust belts, shortening is mainly accommodated by thrust faults that nucleate along décollement levels. Geological and geophysical evidence suggests that these faults might be weak because of a combination of processes such as pressure-solution, phyllosilicates reorientation and delamination, and fluid pressurization. In this study we aim to decipher the processes and the kinetics responsible for weakening of tectonic décollements. We studied the Millaris thrust (Southern Pyrenees): a fault representative of a décollement in its incipient stage. This fault accommodated a total shortening of about 30 meters and is constituted by a 10m thick, intensively foliated phyllonite developed inside a homogeneous marly unit. Detailed chemical and mineralogical analyses have been carried out to characterize the mineralogical change, the chemical transfers and volume change in the fault zone compared to non-deformed parent sediments. We also carried out microstructural analysis on natural and experimentally deformed rocks. Illite and chlorite are the main hydrous minerals. Inside fault zone, illite minerals are oriented along the schistosity whereas chlorite coats the shear surfaces. Mass balance calculations demonstrated a volume loss of up to 50% for calcite inside fault zone (and therefore a relative increase of phyllosilicates contents) because of calcite pressure solution mechanisms. We performed friction experiments in a biaxial deformation apparatus using intact rocks sheared in the in-situ geometry from the Millaris fault and its host sediments. We imposed a range of normal stresses (10 to 50 MPa), sliding velocity steps (3-100 ?m/s) and slide-hold slide sequences (3 to 1000 s hold) under saturated conditions. Mechanical results demonstrate that both fault rocks and parent sediments are weaker than average geological materials (friction ? 0.35). Additionally, fault zone rocks do not show frictional healing, further supporting a non-seismic behavior and prolonged weakness. This study quantitatively demonstrates how tectonic detachments localize in incompetent formations and become readily weak, even after experiencing very small displacements.

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

2013-12-01

48

Multiplicity with a Thrust Cut  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We evaluate the multiplicity of hadrons in the $e^+e^-$-annihilation at a given thrust $T$ in the modified leading-log approximation, including $O(\\sqrt{\\alpha_s})$ corrections. The calculation is done at a large value of $\\tau =1-T$ by the use of the factorisation which takes place in the one-particle-inclusive cross section at a given $\\tau$. At a small $\\tau$, a different type of factorisation takes place, which also enable us to evaluate the multiplicity. Two approaches ...

Kimura, K.; Tesima, K.

1993-01-01

49

Magnetic Bearing  

Science.gov (United States)

AVCON, Inc. produces advanced magnetic bearing systems for industrial use, offering a unique technological approach based on contract work done at Marshall Space Flight Center and Lewis Research Center. Designed for the turbopump of the Space Shuttle main engine, they are now used in applications such as electric power generation, petroleum refining, machine tool operation and natural gas pipelines. Magnetic bearings support moving machinery without physical contact; AVCON's homopolar approach is a hybrid of permanent and electromagnets which are one-third the weight, smaller and more power- efficient than previous magnetic bearings.

1996-01-01

50

Low Thrust Orbital Maneuvers Using Ion Propulsion  

Science.gov (United States)

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

Ramesh, Eric

2011-10-01

51

Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig  

Science.gov (United States)

The Five-Axis, Three-Magnetic-Bearing Dynamic Spin Rig is an apparatus for vibration testing of turbomachine blades in a vacuum at rotational speeds from 0 to 40,000 rpm. This rig includes (1) a vertically oriented shaft on which is mounted an assembly comprising a rotor holding the blades to be tested, (2) two actively controlled heteropolar radial magnetic bearings at opposite ends of the shaft, and (3) an actively controlled magnetic thrust bearing at the upper end of the shaft. This rig is a more capable successor to a prior apparatus, denoted the Dynamic Spin Rig (DSR), that included a vertically oriented shaft with a mechanical thrust bearing at the upper end and a single actively controlled heteropolar radial magnetic bearing at the lower end.

Morrison, Carlos R.; Provenza, Andrew; Kurkov, Anatole; Mehmed, Oral; Johnson, Dexter; Montague, Gerald; Duffy, Kirsten; Jansen, Ralph

2005-01-01

52

Cave Bear  

Science.gov (United States)

Decoding an ancient cave bear. A two-ton, thirteen-foot cave bear, extinct for ten thousand years, has just experienced a rebirth of sorts. From a tooth and a bone, scientists have recovered its entire genetic code.Eddy Rubin, director of the Department of Energy's Joint Genome Institute, says finding genuine cave bear DNA was like looking for a needle in a haystack. The haystack were all the other organisms that were living in the bones and in the tooth of this ancient creature. And the needle was the little bit of the ancient creature's genome DNA, or genes.They used state-of-the-art computer technology to separate the bear genes from the clutter. Jurassic Park fans should note that they can't clone a new cave bear, nor can they recover DNA from creatures as old as the dinosaurs. But they do hope to reconstruct the genetic code of Neanderthals, our closest non-human relatives, to better understand how our own species evolved. This resource contains detailed text description of the research as well as likes for further inquiry.

American Association for the Advancement of Science (;)

2005-08-15

53

The design of linear aerospike thrust cells  

Science.gov (United States)

A study was undertaken to establish, quantify, and compare the design and performance of two candidate thrust cell designs for a linear aerospike rocket engine. The two candidate designs were selected based on a qualitative evaluation of a group of possible designs. The preferred design concepts were a two-dimensional planar thrust cell (2D), and a round throat to rectangular exit three dimensional (3D) thrust cell. These designs were defined using optimum nozzle design methods and a computer aided design system with surfacing capabilities. A quantitative aerothermodynamic analysis was performed to evaluate the performance of these two designs. The performance comparison indicated that the optimum two-dimensional thrust cell had slightly higher overall performance than the non-optimum three dimensional design. The results indicate that other factors, such as cooling capability, structural integrity, and fabricability, will be the leading factors in thrust cell configuration selection.

Booth, T. E.; Vilja, J. O.; Cap, D. P.; McGill, R. J.

1993-06-01

54

Measurements of scramjet thrust in shock tunnels  

Science.gov (United States)

By using results obtained in tests on supersonic combustion of hydrogen in air, the conditions governing model size and operating pressure levels for shock tunnel experiments on models of flight vehicles with scramjet propulsion are established. It is seen that large models are required. The development of the stress wave force balance is then described, and its use as a method of measuring thrust/drag on such models is discussed. Test results on a simple, fully integrated scramjet model, with intakes, combustion chambers, thrust surfaces and exterior surfaces, using a 13 percent silane 87 percent hydrogen fuel mixture, showed that a steady state with thrust generation could be achieved within the shock tunnel test time, and the thrust could be measured. Results are presented for a range of stagnation enthalpies, and show that the scramjet model produces net positive thrust at velocities up to 2.4 km/sec.

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

1995-01-01

55

Oxygen/Alcohol Dual Thrust RCS Engines  

Science.gov (United States)

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

Angstadt, Tara; Hurlbert, Eric

1999-01-01

56

The preliminary design of bearings for the control system of a high-temperature lithium-cooled nuclear reactor  

Science.gov (United States)

The design of bearings for the control system of a fast reactor concept is presented. The bearings are required to operate at temperatures up to 2200 F in one of two fluids, lithium or argon. Basic bearing types are the same regardless of the fluid. Crowned cylindrical journals were selected for radially loaded bearings and modified spherical bearings were selected for bearings under combined thrust and radial loads. Graphite and aluminum oxide are the materials selected for the argon atmosphere bearings while cermet compositions (carbides or nitrides bonded with refractory metals) were selected for the lithium lubricated bearings. Mounting of components is by shrink fit or by axial clamping utilizing differential thermal expansion.

Yacobucci, H. G.; Waldron, W. D.; Walowit, J. A.

1973-01-01

57

Conical Magnetic Bearing Development and Magnetic Bearing Testing for Extreme Temperature Environments  

Science.gov (United States)

The main proposed research of this grant were: to design a high-temperature, conical magnetic bearing facility, to test the high-temperature, radial magnetic bearing facility to higher speeds, to investigate different backup bearing designs and materials, to retrofit the high-temperature test facility with a magnetic thrust bearing, to evaluate test bearings at various conditions, and test several lubricants using a spiral orbit tribometer. A high-temperature, conical magnetic bearing facility has been fully developed using Solidworks. The facility can reuse many of the parts of the current high-temperature, radial magnetic bearing, helping to reduce overall build costs. The facility has the ability to measure bearing force capacity in the X, Y, and Z directions through a novel bearing mounting design. The high temperature coils and laminations, a main component of the facility, are based upon the current radial design and can be fabricated at Texas A&M University. The coil design was highly successful in the radial magnetic bearing. Vendors were contacted about fabrication of the high temperature lamination stack. Stress analysis was done on the laminations. Some of the components were procured, but due to budget cuts, the facility build up was stopped.

Keith, Theo G., Jr.; Jansen, Mark

2004-01-01

58

Low thrust chemical rocket technology  

Science.gov (United States)

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

Schneider, Steven J.

1992-01-01

59

Computer-aided selection of materials for cryogenic turbopump bearings  

Science.gov (United States)

The life requirement for the angular contact ball bearings in the Space Shuttle Main Engine (SSME) high-pressure-oxygen turbopump (HPOTP) is 7.5 hours. In actual operation, significantly shorter service life has been experienced. The objective of this current program is to identify bearing materials and/or materials processing techniques offering significant potential for extending HPOTP bearing performance life. A thermomechanical analysis of the HPOTP shaft/bearing system was performed with the SHABERTH (SHaft-BEaring-THermal) computer program. Bearing fatigue life, ball-race contact stress, heat generation rate, bulk ring temperatures, and circumferential stress in the inner rings were quantified as functions of radial load, thrust load, and ball-race contact friction. The analysis results were used to formulate criteria that are being used for the selection of special materials for future turbopump bearings.

Maurer, R. E.; Pallini, R. A.

1985-01-01

60

Design analysis and performance assessment of hybrid magnetic bearings for a rotary centrifugal blood pump.  

Science.gov (United States)

A hybrid magnetic bearing system was designed for a rotary centrifugal blood pump being developed to provide long-term circulatory support for heart failure patients. This design consists of two compact bearings to suspend the rotor in five degrees-of-freedom with single axis active control. Permanent magnets are used to provide passive radial support and electromagnets to maintain axial stability of the rotor. Characteristics of the passive radial and active thrust magnetic bearing system were evaluated by the electromagnetic finite element analysis. A proportional-integral-derivative controller with force balance algorithm was implemented for closed loop control of the magnetic thrust bearing. The control position is continuously adjusted based on the electrical energy in the bearing coils, and thus passive magnetic forces carry static thrust loads to minimize the bearing current. Performance of the magnetic bearing system with associated control algorithm was evaluated at different operating conditions. The bearing current was significantly reduced with the force balance control method and the power consumption was below 0.5 W under various thrust loads. The bearing parameters predicted by the analysis were validated by the experimental data. PMID:19381082

Ren, Zhaohui; Jahanmir, Said; Heshmat, Hooshang; Hunsberger, Andrew Z; Walton, James F

2009-01-01

 
 
 
 
61

Bearing structures  

International Nuclear Information System (INIS)

A hydrostatic bearing for the lower end of the vertical shaft of a sodium pump comprises a support shell encircling the shaft and a bush located between the shell and shaft. Liquid sodium is fed from the pump outlet to the bush/shaft and bush/shell interfaces to provide hydrostatic support. The bush outer surface and the shell inner surface are of complementary part-spherical shape and the bush floats relative to the shaft so that the bush can align itself with the shaft axis. Monitoring of the relative rotational speed of the bush with respect to the shaft (such rotation being induced by the viscous drag forces present) is also performed for the purposes of detecting abnormal operation of the bearing or partial seizure, at least one magnet is rotatable with the bush, and a magnetic sensor provides an output having a frequency related to the speed of the bush. (author)

1987-02-10

62

GSFC Technology Thrusts and Partnership Opportunities  

Science.gov (United States)

This slide presentation reviews the technology thrusts and the opportunities to partner in developing software in support of the technological advances at the Goddard Space Flight Center (GSFC). There are thrusts in development of end-to-end software systems for mission data systems in areas of flight software, ground data systems, flight dynamic systems and science data systems. The required technical expertise is reviewed, and the supported missions are shown for the various areas given.

Le Moigne, Jacqueline

2010-01-01

63

FROM STUDIES ON THE THRUST IN SWIMMING  

Directory of Open Access Journals (Sweden)

Full Text Available Swimming speed is determined by many factors, including weight preparation of the swimmer which is one of the most important ones. This power is directly related to the speed a swimmer can reach in water, that is the value of thrust. The aim of the study was to establish the level of thrust and swimming speed of the 2nd year students (n=20 of the University School of Physical Education (USPE in Pozna? and to compare them with the results of study from 1983 in which the 4th year students (n=20 of the USPE in Pozna? were studied. The current study was carried out in the context of the long-term changes in swimming technique. Research methods: measurement of thrust in real conditions was performed using a prototype device for the measurement of thrust of a swimmer which makes it possible to register the force in the water environment; swimming speed was established on the basis of the time needed to cover the distance of 25 metres, according to the regulations of the Polish Swimming Association. Conclusions: the students taking part in the 1983 study had higher values of thrust, but a lower speed than the students taking part in the 2006 study, which suggests that apart from the thrust the technique of swimming has a important influence of the swimming speed.

Strzelczyk, R.

2008-07-01

64

Multiphysics Nuclear Thermal Rocket Thrust Chamber Analysis  

Science.gov (United States)

The objective of this effort is t o develop an efficient and accurate thermo-fluid computational methodology to predict environments for hypothetical thrust chamber design and analysis. The current task scope is to perform multidimensional, multiphysics analysis of thrust performance and heat transfer analysis for a hypothetical solid-core, nuclear thermal engine including thrust chamber and nozzle. The multiphysics aspects of the model include: real fluid dynamics, chemical reactivity, turbulent flow, and conjugate heat transfer. The model will be designed to identify thermal, fluid, and hydrogen environments in all flow paths and materials. This model would then be used to perform non- nuclear reproduction of the flow element failures demonstrated in the Rover/NERVA testing, investigate performance of specific configurations and assess potential issues and enhancements. A two-pronged approach will be employed in this effort: a detailed analysis of a multi-channel, flow-element, and global modeling of the entire thrust chamber assembly with a porosity modeling technique. It is expected that the detailed analysis of a single flow element would provide detailed fluid, thermal, and hydrogen environments for stress analysis, while the global thrust chamber assembly analysis would promote understanding of the effects of hydrogen dissociation and heat transfer on thrust performance. These modeling activities will be validated as much as possible by testing performed by other related efforts.

Wang, Ten-See

2005-01-01

65

Design and Fabrication of Gas Bearings for Brayton Cycle Rotating Unit.  

Science.gov (United States)

Analysis, design, and testing of two types of pivoted pad journal bearings and a spiral-grooved thrust bearing suitable for direct installation into the NASA 2 to 15 KW Brayton Cycle Rotating Unit (BRU) have been accomplished. Both types of tilting pad be...

A. Frost J. M. Tessarzik E. B. Arwas W. D. Waldron

1973-01-01

66

A thrust balance for low power hollow cathode thrusters  

Science.gov (United States)

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%.

Frollani, D.; Coletti, M.; Gabriel, S. B.

2014-06-01

67

Axisymmetric thrust-vectoring nozzle performance prediction  

International Nuclear Information System (INIS)

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

1998-05-19

68

Pulsed thrust measurements using electromagnetic calibration techniques  

International Nuclear Information System (INIS)

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

2011-03-01

69

Pulsed thrust measurements using electromagnetic calibration techniques  

Energy Technology Data Exchange (ETDEWEB)

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

Tang Haibin; Shi Chenbo; Zhang Xin' ai; Zhang Zun; Cheng Jiao [School of Astronautics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China)

2011-03-15

70

Low thrust NTP for manned Mars operations  

International Nuclear Information System (INIS)

The impact on manned Mars operations of selecting a nuclear thermal propulsion (NTP) module with a relatively low total thrust, in the 222--445 kN (50--100 klbf) range, is explored. The propulsion module may consist of one or more engines. Selection of a low total thrust is robust across a wide range of payload masses provided perigee kicks are utilized for trans-Mars insertion (TMI). The longer time taken for TMI when using a low total thrust and perigee kicks allows for extensive system evaluation before commitment to Earth escape, but will require fuels with lifetimes of at least a few hours. Longer fuel life could be obtained without using advanced fuels by operating at lower fuel temperatures later in the mission. The additional traversals through the Van Allen belts inherent with using perigee kicks for TMI does not significantly increase the radiation exposure of the crew. Negative reactivity from xenon buildup between perigee kicks can be mitigated by coasting on the intermediate orbits, by altering the selection of the intermediate orbits, by deep throttling, or by building in sufficient excess reactivity. Thrust misalignments of a realistic magnitude do not pose an Earth impact hazard. Engine crosstalk in clusters is a very manageable problem. High propulsion module reliability can be achieved with a propulsion module consisting of a cluster of three or four small engines without dropping the module thrust-to-weight ratio below an acceptable level. A total design thrust in the 222--445 kN range is high enough for Earth return with only one of the engines of the cluster operating

1993-01-10

71

Evaluation of antifriction bearing lubrication methods on motor life-cycle cost  

Energy Technology Data Exchange (ETDEWEB)

The number 1 cause of induction motor failures is bearing failure. Antifriction bearing failures most commonly are the consequences of inadequate lubrication. Antifriction motor bearings are found in four lubrication configurations: regreasable, sealed, oil mist, and oil lubricated. Bearings are oil lubricated when the operating conditions (i.e., bearing size, speed, thrust, etc.) require it. However, there is much debate about the best lubrication configuration, given a choice between regreasable, sealed, or oil-misted bearings. Within their own rights, all three methods have their advantages. Selection of the proper configuration is dependent upon many factors, such as motor size/type (i.e., bearing size/type), plant maintenance practice, bearing replacement availability/cost, duty cycle, environmental conditions, and downtime cost. This paper discusses the relationship between these factors and lubrication configuration, and presents an analysis of the subsequent impact on bearing life and system cost.

Hodowanec, M.M.

1999-12-01

72

A ?Newton thrust-stand for LISA  

International Nuclear Information System (INIS)

The success of the LISA project depends on the ability of the disturbance reduction system to shield the proof masses from all external forces and to maintain tight pointing requirements relative to the other two spacecrafts. ?N-thrusters are required to compensate for the solar radiation pressure acting on the spacecraft. The force noise from these thrusters must be low enough not to disturb the freely floating proof masses. To date, these noise requirements have not been demonstrated, mostly because no thrust-stand exists with sufficient sensitivity. We present the status of our ?Newton thrust-stand that will verify that the thrusters proposed for LISA will meet the noise requirements

2002-04-07

73

A six degree-of-freedom thrust sensor for a labscale hybrid rocket  

Science.gov (United States)

A six degree-of-freedom thrust sensor was designed, constructed, calibrated, and tested using the labscale hybrid rocket at the University of Arkansas at Little Rock. The system consisted of six independent legs: one parallel to the axis of symmetry of the rocket for main thrust measurement, two vertical legs near the nozzle end of the rocket, one vertical leg near the oxygen input end of the rocket, and two separated horizontal legs near the nozzle end. Each leg was composed of a rotational bearing, a load cell, and a universal joint above and below the load cell. The leg was designed to create point contact along only one direction and minimize the non-axial forces applied to the load cell. With this system, force in each direction and moments for roll, pitch, and yaw can be measured. The system was calibrated and tested using a labscale hybrid rocket using gaseous oxygen and hydroxyl-terminated polybutadiene solid fuel. The thrust stand proved to be stable during calibration tests. Thrust force vector components and roll, pitch, and yaw moments were calculated for test firings with an oxygen mass flow rate range of 0.0174-0.0348 kg s-1.

Wright, Ann M.; Wright, Andrew B.; Born, Traig; Strickland, Ryan

2013-12-01

74

Thrust Vectoring for Lateral-Directional Stability.  

Science.gov (United States)

The advantages and disadvantages of using thrust vectoring for lateral-directional control and the effects of reducing the tail size of a single-engine aircraft were investigated. The aerodynamic characteristics of the F-16 aircraft were generated by usin...

L. R. Peron T. Carpenter

1992-01-01

75

Lifting Surface Theory for Thrust Augmenting Ejectors.  

Science.gov (United States)

The circulation theory of airfoil lift has been applied to predict the static performance of thrust augmenting ejectors. The ejector shroud is considered to be 'flying' in the velocity field induced by the entrainment of the primary jets, so that the thru...

P. M. Bevilaqua

1982-01-01

76

Development of an indirect counterbalanced pendulum optical-lever thrust balance for micro- to millinewton thrust measurement  

International Nuclear Information System (INIS)

This paper describes the design and testing of an indirect hanging pendulum thrust balance using a laser-optical-lever principle to provide micro- to millinewton thrust measurement for the development of electric propulsion systems. The design philosophy allows the selection of the total thrust range in order to maximize resolution through a counterbalanced pendulum principle, as well as passive magnetic damping in order to allow relatively rapid transient thrust measurement. The balance was designed for the purpose of hollow cathode microthruster characterization, but could be applied to other electric propulsion devices in the thrust range of micro- to millinewtons. An initial thrust characterization of the T5 hollow cathode is presented

2010-10-01

77

Conceptual Design and Feasibility of Foil Bearings for Rotorcraft Engines: Hot Core Bearings  

Science.gov (United States)

Recent developments in gas foil bearing technology have led to numerous advanced high-speed rotating system concepts, many of which have become either commercial products or experimental test articles. Examples include oil-free microturbines, motors, generators and turbochargers. The driving forces for integrating gas foil bearings into these high-speed systems are the benefits promised by removing the oil lubrication system. Elimination of the oil system leads to reduced emissions, increased reliability, and decreased maintenance costs. Another benefit is reduced power plant weight. For rotorcraft applications, this would be a major advantage, as every pound removed from the propulsion system results in a payload benefit.. Implementing foil gas bearings throughout a rotorcraft gas turbine engine is an important long-term goal that requires overcoming numerous technological hurdles. Adequate thrust bearing load capacity and potentially large gearbox applied radial loads are among them. However, by replacing the turbine end, or hot section, rolling element bearing with a gas foil bearing many of the above benefits can be realized. To this end, engine manufacturers are beginning to explore the possibilities of hot section gas foil bearings in propulsion engines. This overview presents a logical follow-on activity by analyzing a conceptual rotorcraft engine to determine the feasibility of a foil bearing supported core. Using a combination of rotordynamic analyses and a load capacity model, it is shown to be reasonable to consider a gas foil bearing core section. In addition, system level foil bearing testing capabilities at NASA Glenn Research Center are presented along with analysis work being conducted under NRA Cooperative Agreements.

Howard, Samuel A.

2007-01-01

78

Mechanism of the formation of oil and gas bearing platform structures. [Siberia  

Energy Technology Data Exchange (ETDEWEB)

On the basis of analysis of oil and gas bearing platform structures of the Volgo-Ural oblast, Western-Siberian and Eastern Siberian platforms the conclusion is drawn that platform structures are formed under conditions of horizontal compression of the earth crust as a result of differentiated lateral movements of the tectonic plates along surfaces of overthrusts and thrusts. Pre-plate foundations both of ancient and of young platforms have overthrust and thrust structure.

Kamaletdinov, M.A.; Kazantseva, T.T.

1981-01-01

79

Spiral Groove Aerodynamic Bearings  

Directory of Open Access Journals (Sweden)

Full Text Available In order to research the conical spiral groove aerodynamic bearings, the bearing's lubrication analysis mathematical model is established. The Reynolds equation of the laminar flow condition is used to calculate the 3D pressure distribution by the locally finite difference method. The influence law of the gas film pressure distribution on the bearing performance is revealed by researching the nonlinear dynamic characteristic of gas film. It reveals the laws that the effect of the bearing structural parameters on the gas film pressure distribution and the bearing capacity. The results show that the spiral groove change the gas film thickness distribution and the gas film pressure distribution and achieve good bearing dynamic pressure effect, which improve the bearing performance and the bearing stability; The structure parameters affect the gas film pressure distribution and the static characteristics. Therefore, a reasonable choice of bearing structural parameters contributes to improve the bearing's static characteristics and bearing capacity.

Jia Chen-Hui

2013-01-01

80

Thrusting and gravel progradation in foreland basins: A test of post-thrusting gravel dispersal  

Energy Technology Data Exchange (ETDEWEB)

The use of gravels as syntectonic indicators of thrusting has recently been questioned by foreland-basin models that assign gravels to a post-thrusting interval of progradation, except in very proximal areas. On the basis of precise temporal control provided by magnetostratigraphically dated sections, the history of gravel progradation after a major thrusting and uplift event in the northwestern Himalaya is shown to be a virtually syntectonic phenomenon. Despite considerable crustal subsidence driven by a thick-skinned thrust, gravels prograded {approximately} 70 km during a 1.5-m.y.-long thrusting event. By 3 m.y. after the start of thrusting, gravels extended more than 110 km into the basin. Although delayed gravel progradation appears appropriate for many Rocky Mountain foreland basins, it is clearly not valid for the Himalaya. The authors attribute the difference in depositional response between these basins to difference in the quantity of sediment supplied to them (sediment starved vs. overfilled), the availability of resistates in the source area, and the size of the antecedent drainage.

Burbank, D.W.; Beck, R.A.; Hobbs, R. (Univ. of Southern California, Los Angeles (USA)); Raynolds, R.G.H. (Amoco Production Company, Houston, TX (USA)); Tahirkheli, R.A.K. (Peshawar Univ. (Pakistan))

1988-12-01

 
 
 
 
81

Passive magnetic bearing configurations  

Energy Technology Data Exchange (ETDEWEB)

A journal bearing provides vertical and radial stability to a rotor of a passive magnetic bearing system when the rotor is not rotating and when it is rotating. In the passive magnetic bearing system, the rotor has a vertical axis of rotation. Without the journal bearing, the rotor is vertically and radially unstable when stationary, and is vertically stable and radially unstable when rotating.

Post, Richard F. (Walnut Creek, CA)

2011-01-25

82

NATURAL BARRIERS TARGETED THRUST FY 2004 PROJECTS  

Energy Technology Data Exchange (ETDEWEB)

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.

NA

2005-07-27

83

MATERIALS PERFORMANCE TARGETED THRUST FY 2004 PROJECTS  

International Nuclear Information System (INIS)

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

2005-01-01

84

Solar electric propulsion thrust subsystem development  

Science.gov (United States)

The Solar Electric Propulsion System developed under this program was designed to demonstrate all the thrust subsystem functions needed on an unmanned planetary vehicle. The demonstration included operation of the basic elements, power matching input and output voltage regulation, three-axis thrust vector control, subsystem automatic control including failure detection and correction capability (using a PDP-11 computer), operation of critical elements in thermal-vacuum-, zero-gravity-type propellant storage, and data outputs from all subsystem elements. The subsystem elements, functions, unique features, and test setup are described. General features and capabilities of the test-support data system are also presented. The test program culminated in a 1500-h computer-controlled, system-functional demonstration. This included simultaneous operation of two thruster/power conditioner sets. The results of this testing phase satisfied all the program goals.

Masek, T. D.

1973-01-01

85

Calculating Track Thrust with Track Functions  

CERN Document Server

In e+e- event shapes studies at LEP, two different measurements were sometimes performed: a "calorimetric" measurement using both charged and neutral particles, and a "track-based" measurement using just charged particles. Whereas calorimetric measurements are infrared and collinear safe and therefore calculable in perturbative QCD, track-based measurements necessarily depend on non-perturbative hadronization effects. On the other hand, track-based measurements typically have smaller experimental uncertainties. In this paper, we present the first calculation of the event shape track thrust and compare to measurements performed at ALEPH and DELPHI. This calculation is made possible through the recently developed formalism of track functions, which are non-perturbative objects describing how energetic partons fragment into charged hadrons. By incorporating track functions into soft-collinear effective theory, we calculate the distribution for track thrust with next-to-leading logarithmic resummation. Due to a p...

Chang, Hsi-Ming; Thaler, Jesse; Waalewijn, Wouter J

2013-01-01

86

THRUST PREDICTION PROGRAM FOR MARINE JET POWER  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Marine Jet Power, MJP wishes to investigate the possibility of transforming their current Thrust Prediction Program, TPP written in C++ source code into a more up to date tool for their sales staff. The old TPP, though an accurate and precise tool, is not documented and lacks commentaries in the source code. Therefore the beginning of this master thesis was about documenting and investigates what methods were used to calculate the performance of the water jet system.The next step was splittin...

Bergsek, Mattias

2011-01-01

87

Passive magnetic bearing  

International Nuclear Information System (INIS)

The paper presents a special design of a passive magnetic bearing with permanent magnets on the fixed and the rotating part of the bearing. Peculiarity of the presented passive magnetic bearing is its ability to take radial and axial loads in both directions by using axially magnetized permanent magnets. A 3D finite element method (3D FEM) is used for analysis of magnetic conditions in the bearing. The performance of the presented magnetic bearing was determined by the Maxwell Stress Method

2004-05-01

88

Evolutionary Computing for Low-thrust Navigation  

Science.gov (United States)

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.

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

2005-01-01

89

Conical Magnetic Bearings Developed for Active Stall Control in Gas Turbine Engines  

Science.gov (United States)

Active stall control is a current research area at the NASA Glenn Research Center that offers a great benefit in specific fuel consumption by allowing the gas turbine to operate beyond the onset of stall. Magnetic bearings are being investigated as a new method to perform active stall control. This enabling global aviation safety technology would result in improved fuel efficiency and decreased carbon dioxide emissions, as well as improve safety and reliability by eliminating oil-related delays and failures of engine components, which account for 40 percent of the commercial aircraft departure delays. Active stall control works by perturbing the flow in front of the compressor stage such that it cancels the pressure wave, which causes the compressor to go into stall. Radial magnetic bearings are able to whirl the shaft so that variations in blade tip leakage would flow upstream causing a perturbation wave that could cancel the rotating stall cell. Axial or thrust magnetic bearings cannot be used to cancel the surge mode in the compressor because they have a very low bandwidth and thus cannot modulate at a high enough frequency. Frequency response is limited because the thrust runner cannot be laminated. To improve the bandwidth of magnetic thrust bearings, researchers must use laminations to suppress the eddy currents. A conical magnetic bearing can be laminated, resulting in increased bandwidth in the axial direction. In addition, this design can produce both radial and thrust force in a single bearing, simplifying the installation. The proposed solution combines the radial and thrust bearing into one design that can be laminated--a conical magnetic bearing. The new conical magnetic bearing test rig, funded by a Glenn fiscal year 2002 Director's Discretionary Fund, was needed because none of the existing rigs has an axial degree of freedom. The rotor bearing configuration will simulate that of the main shaft on a gas turbine engine. One conical magnetic bearing replaces the ball bearing in front of the compressor, and the second replaces the roller bearing behind the burner. The rig was made operational to 10,000 rpm under Smart Efficient Components funding, and both position and current adaptive vibration control have been demonstrated. Upon program completion, recommendations will be made as to the efficacy of the conical magnetic bearing for active stall control.

Trudell, Jeffrey J.; Kascak, Albert F.; Provenza, Andrew J.; Buccieri, Carl J.

2004-01-01

90

The Zagros hinterland fold-and-thrust belt in-sequence thrusting, Iran  

Science.gov (United States)

The collision of the Iranian microcontinent with the Afro-Arabian continent resulted in the deformation of the Zagros orogenic belt. The foreland of this belt in the Persian Gulf and Arabian platform has been investigated for its petroleum and gas resource potentials, but the Zagros hinterland is poorly investigated and our knowledge about its deformation is much less than other parts of this orogen. Therefore, this work presents a new geological map, stratigraphic column and two detailed geological cross sections. This study indicates the presence of a hinterland fold-and-thrust belt on northeastern side of the Zagros orogenic core that consists of in-sequence thrusting and basement involvement in this important part of the Zagros hinterland. The in-sequence thrusting resulted in first- and second-order duplex systems, Mode I fault-bend folding, fault-propagation folding and asymmetric detachment folding which indicate close relationships between folding and thrusting. Study of fault-bend folds shows that layer-parallel simple shear has the same role in the southeastern and northwestern parts of the study area (?e = 23.4 ± 9.1°). A major lateral ramp in the basement beneath the Talaee plain with about one kilometer of vertical offset formed parallel to the SW movement direction and perpendicular to the major folding and thrusting.

Sarkarinejad, Khalil; Ghanbarian, Mohammad Ali

2014-05-01

91

Paleostress analysis of the Osning Thrust, Germany  

Science.gov (United States)

The Osning Thrust is a 100 km-scale NW-SE fault separating the Lower Saxony Basin to the NE from the Münsterland Basin to the SE. The fault has accommodated a polyphase deformation that started at least when it acted as one of the normal border faults of the Jurassic Lower Saxony Basin. Tectonic inversion of the basin in Late Cretaceous-Early Paleocene times led to the development of the SE-vergent Osning Thrust and to folding of rocks. A paleostress analysis was carried out in order to decipher the polyphase kinematics of the Osning Thrust. The fault slip data were collected in the folded Albian to Turonian stratigraphic units of the Münsterland basin, in the SE vicinity of a 20 km-long steep segment of the Osning Thrust. Fault slip data in sufficient amount to perform paleostress inversion were collected in 10 sites among 23 visited outcrops. Abundant minor faults trend sub-parallel to the NW-SE steep segment of the Osning Thrust but, surprisingly, they are dextral (and not reverse) in type. Another major set of E-W striking minor faults is remarkable. It corresponds to conjugate systems of either reverse or normal faults and to oblique- to strike-slip faults in a less extent. The paleostress tensors reveal a ca. N-S compression recorded in 5 locations under which the NW-SE steep faults were dextral and the E-W striking S- and N- dipping faults were reverse. Six stress tensors fit with a ca. N-S extension. They are calculated from E-W striking S- and N- dipping normal to oblique normal faults. The same N-S trend of minimum stress axis is also recorded with NNE-SSW dextral and E-W sinistral faults. We propose that along the studied segment of the Osning Thrust a N-S compressional stress field led to the inversion of the Lower Saxony Basin and that slip along the Osning Thrust was oblique reverse. At two locations, the N-S compressive stress states affected the rock prior to tilting of the beds (herein, due to folding) and at one site, the normal faults of the N-S extension clearly cut across reverse faults of the N-S compression. These two observations allow to propose a chronology between the reconstructed stress fields. While the N-S compression is presumably linked to the Late Cretaceous-Early Palaeocene inversion of the Lower Saxony Basin, the successive E-W extension is not constrained in age. However, it is known that tensional stresses have largely affected the west European platform in Oligocene times and this N-S extension revealed by the present study might be related to this tectonic event.

Saintot, Aline; Kozakovski, Anna; Pascal, Christophe

2013-04-01

92

Axial inlet conversion to a centrifugal compressor with magnetic bearings  

Energy Technology Data Exchange (ETDEWEB)

NOVA's Alberta Gas Transmission Division transports natural gas via pipeline throughout the province of Alberta, Canada, exporting it to eastern Canada, US, and British Columbia. There is a continuing effort to operate the facilities and pipeline at the highest possible efficiency. One area being addressed to improve efficiency is compression of the gas. By improving compressor efficiency, fuel consumption and hence operating costs can be reduced. One method of improving compressor efficiency is by converting the compressor to an axial inlet configuration, a conversion that has been carried out more frequently in the past years. Concurrently, conventional hydrodynamic bearings have been replaced with magnetic bearings on many centrifugal compressors. This paper discusses the design and installation for converting a radial overhung unit to an axial inlet configuration, having both magnetic bearings and a thrust reducer. The thrust reducer is required to reduce axial compressor shaft loads, to a level that allows the practical installation of magnetic bearings within the space limitations of the compressor (Bear and Gibson, 1992).

Novecosky, T. (NOVA Corp., Edmonton, Alberta (Canada))

1994-01-01

93

Development and Testing of an Axial Halbach Magnetic Bearing  

Science.gov (United States)

The NASA Glenn Research Center has developed and tested a revolutionary Axial Halbach Magnetic Bearing. The objective of this work is to develop a viable non-contact magnetic thrust bearing utilizing Halbach arrays for all-electric flight, and many other applications. This concept will help to reduce harmful emissions, reduce the Nation s dependence on fossil fuels and mitigate many of the concerns and limitations encountered in conventional axial bearings such as bearing wear, leaks, seals and friction loss. The Axial Halbach Magnetic Bearing is inherently stable and requires no active feedback control system or superconductivity as required in many magnetic bearing designs. The Axial Halbach Magnetic Bearing is useful for very high speed applications including turbines, instrumentation, medical systems, computer memory systems, and space power systems such as flywheels. Magnetic fields suspend and support a rotor assembly within a stator. Advanced technologies developed for particle accelerators, and currently under development for maglev trains and rocket launchers, served as the basis for this application. Experimental hardware was successfully designed and developed to validate the basic principles and analyses. The report concludes that the implementation of Axial Halbach Magnetic Bearings can provide significant improvements in rotational system performance and reliability.

Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

2006-01-01

94

Active Magnetic Bearings.  

Science.gov (United States)

The paper deals with a nonconventional type of bearing that is active magnetic bearing (AMB). Rotor suspension in AMB is achieved by attractive forces of electromagnetic poles. To stabilize the rotor position, the automatic control system is introduced. T...

Y. N. Zhuravlyov

1992-01-01

95

Thrust control in supersonic flight by external burning  

Energy Technology Data Exchange (ETDEWEB)

Control of the thrust and thrust vector angle is difficult for reuseable space transportation systems, when SERN-nozzles are used. In this paper the influence of external burning of hydrogen on the thrust and on the thrust vector angle for the research configuration ELAC 1 is investigated. The Navier-Stokes equations for viscous, compressible, reactive flows are solved. The mixture composition is calculated with the assumption of chemical equilibrium. The conservation equations are discretized on blockstructured, curvilinear grids with second-order accuracy. The resulting system of linear algebraic equations is solved with an alternating line-relaxation method. Results are presented for a free stream Mach number of Ma{sub {infinity}}=3.8. The thrust and especially the thrust vector angle can markedly be improved. (orig.)

Kropp, M.; Henze, A. [Technische Hochschule Aachen (Germany). Lehrstuhl fuer Stroemungslehre und Aerodynamisches Inst.

1999-12-01

96

OMV/VTE variable thrust engine analysis  

Science.gov (United States)

The objective of the present work is to develop a predictive CFD based analytical tool for the Variable Thrust Engine (VTE) in the Orbital Maneuvering Vehicle (OMV). This objective is being accomplished within the framework of the Los Alamos KIVA computer code for chemically reactive flows with sprays. For the OMV application, the main structure of KIVA is to be retained while reformulating many of the phenomenological submodels, enhancing some of the numerics, and adding more features. The analytical model consists of the general conservation equations for two-phase reactive flows and of submodels for turbulence, chemical reactions, and bipropellant sprays. Tailoring this model to the OMV engine brings about the added complexities of combustion and flow processes that occur in a liquid hypergolic propellant rocket chamber. This report exposes the foundation upon which the analytical tool is being constructed and developed. Results from a cursory computational exercise involving the simulation of the flow and combustion processes in a hypothetical N2H4/N204 rocket engine thrust chamber is presented and discussed.

Larosillere, L.; Litchford, R.; Jeng, S. M.

1995-01-01

97

Cretaceous biostratigraphy in the Wyoming thrust belt  

Energy Technology Data Exchange (ETDEWEB)

Biostratigraphy is essential to exploration for oil and gas in the Wyoming thrust belt because fossils provide a temporal framework for interpretation of events of faulting, erosion, sedimentation, and the development of hydrocarbon traps and migration pathways. In the Cretaceous section, fossils are especially useful for dating and correlating repetitive facies of different ages in structurally complex terrain. The biostratigraphic zonation for the region is based on megafossils (chiefly ammonites), which permit accurate dating and correlation of outcrop sections, and which have been calibrated with the radiometric time scale for the Western Interior. Molluscan and vertebrate zone fossils are difficult to obtain from the subsurface, however, and ammonities are restricted to rocks of margin origin. Palynomorphs (plant microfossils) have proven to be the most valuable fossils in investigations of stratigraphy and structures in the subsurface of the thrust belt because palynomorphs can be recovered from drill cuttings. Palynomorphs also are found in both marine and nonmarine rocks and can be used for correlation between facies. In this paper, stratigraphic ranges of selected Cretaceous marine and nonmarine palynomorphs in previously designated reference sections in Fossil Basin, Wyoming, are correlated with the occurrence of ammonities and other zone fossils in the same sections. These correlations can be related to known isotopic ages, and they contribute to the calibration of palynomorph ranges in the Cretaceous of the Western Interior.

Nichols, D.J. (U.S. Geological Survey, Denver, CO); Jacobson, S.R.

1982-07-01

98

Effect of tongue thrust swallowing on position of anterior teeth  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Background and aims. There is no consensus about the effect of tongue thrusting on incisor position. The purpose of this study was to evaluate the position of anterior teeth in growing children with tongue thrust swallowing. Materials and methods. In the present study 193 subjects with an age range of 9 to 13 years participated. All the patients were examined by a trained investigator and those having tongue thrust swallowing were selected and the position of their anterior teeth was com...

2009-01-01

99

Active Dual Thrust Modulation of a Solid Rocket Motor  

Science.gov (United States)

Based on a combustion characteristic that some propellants cannot burn in an intermediate pressure range while they can burn at lower and higher pressure, an active thrust modulation system was developed. The motor changed its thrust in dual combustion mode. It chose alternately high and low thrusts during combustion. The transitions from the low mode to the high mode were attained by a secondary ignition system, and those from the high mode to the low mode were done by a brief gas release system. Up to three times mode transitions were successfully demonstrated. Required time for the mode transitions and the effects of the thrust modulations on the thrust performance were evaluated. On the present motor scale, the transition time from the low mode to the high mode ranged from 0.12 s to 0.23 s, and that from the high mode to the low mode was from 0.19 s to 0.38 s. The thrust variable range was adjustable by the throat area. The ratio of the low-mode thrust to the high mode thrust was variable from 3 to 5. Specific impulse was decreased from 195 s to 175 s, when the number of thrust modulations was increased.

Tanaka, Masafumi; Yokomine, Yasushi

100

Fault interaction along the Central Andean thrust front: The Las Peñas thrust, Cerro Salinas thrust and the Montecito Anticline  

Science.gov (United States)

The region in west-central Argentina between the thin-skinned Precordillera and the thick-skinned Sierras Pampeanas structural domain is among the most active zones of thrust tectonics in the world. We quantify the rates of deformation on the east-vergent Las Peñas thrust (LPT), and the west-vergent Cerro Salinas thrust (CST). The Montecito anticline (MA) is located at their intersection. We mapped three key locations, collected stratigraphic logs from the MA, dated three ashes using U-Pb in zircon and dated 10 terraces using cosmogenic Be-10 depth profiles. Five terrace levels are present where the Rio Las Peñas crosses the LPT, up to 45 m above the modern river. Cosmogenic dating of the uppermost terrace (T1) yields and age of 123.8 +26.5/-12.3 ka. A reconstruction of this surface using a blind thrust rupture scenario indicates 73 +/- 7 m horizontal shortening and 34 +/- 3 m vertical displacement. Shortening across the structure is therefore 0.59 +0.10/-0.13 mm/yr with a vertical uplift rate of 0.27 +0.05/-0.06 mm/a. Previous work indicates higher rates to the south on the order of 2 mm/yr (Schmidt et al., 2011). Lower terraces give ages of 38.0 +11/-6.2 ka (T2) and 1.5 +5.0/-0.6 ka (T4). Three terrace levels are preserved near the center of the CST. The middle surface (T2) is folded across the axis of the structure and yields an age of 112.5 +33/-14.4 ka. Given 22.9 m surface uplift, this indicates a vertical uplift rate of 0.20 +0.05/-0.06 mm/yr, similar to the rate on the LPT. The upper terrace (T1) yields a younger age (97.1 +29.8/-12.4 ka); the T1 and T2 ages overlap within uncertainty, indicating rapid river incision at the time of their formation. An intercalated ash within the Neogene strata gives an age of 16.2 +/- 0.2. Previous work indicates long-term shortening rates of 0.8 mm/yr (Verges et al., 2007) and that the CST initiated after 8.5 Ma. The lowermost unit exposed in the MA is the Los Pozos Fm., with no indication of syn-depositional deformation. An intercalated ash from the top of this formation yields an age of 5.76 +/- 0.09 Ma. Internal unconformities are present within the overlying transitional unit and the Mogotes Fm., indicating deformation post-dates 5.8 Ma in the MA. An ash within the Mogotes Fm. is 1.52 +/- 0.06 Ma. Slip is modeled as 3.5 km reverse slip across an east-dipping dislocation with a 45 degree dip. This suggests horizontal shortening and vertical uplift of 0.42 mm/yr since the onset of deformation. Uplifted terraces near the center of the MA are 4.7 +0.8/-0.3 ka (T2) and 1.9 +3.4/-1.9 ka (T3), 6 and 4.6 m above the modern river, respectively. This suggests recent vertical uplift or incision rates of 1.3-2.4 mm/yr. These data suggest that deformation in the MA is comparable to that at the LPT and CST. Deformation in the MA could be accelerating, but alternatively, river incision could be accelerating due to climate change.

Schoenbohm, L. M.; Costa, C. H.; Brooks, B. A.; Bohon, W.; Gardini, C.; Cisneros, H.

2013-12-01

 
 
 
 
101

Time to reconcile thermal inversion models around thrusts  

Science.gov (United States)

Inversion of metamorphic thermal isograds is commonly observed around mega-thrusts, particularly in close association with major thrusts in collision belts. However, the processes leading to such thermal inversion still constitute an open issue. Various models have already addressed their possible syn-deformational origin during thrusting. However, because they concentrated on specific contexts and processes, none of these models has achieved a general consensus. Hence, in order to reconcile these different models of syn-deformational thermal inversion, it becomes crucial to find a way allowing to determine the key process controlling the thermal evolution for any thrust zone. Here, we present a dimensional analysis allowing to quantify the relative control of heat diffusion, advection and shear heating on the thermal evolution around thrusts. Our analytical solution invokes parameters that can define any thrust scenario in terms of kinematics, rheological strength and thermal context. Our study focuses mainly on the role of the thrust thickness, h, the shear zone dip angle, ?, the convergence velocity, V, and the effective viscosity, ?, of the shear zone. Our dimensional analysis shows that for typical values applicable to intracontinental thrusts (h = 1-5 km, ? = 15-45°, V = 1-3 cm/yr, ? = 1e19-1e21 Pa.s) heat diffusion as well as advection as well as shear heating can be the dominant process controlling the thermal evolution around thrusts. This result explains the difficulty of finding a unique model for inverted metamorphism. From this, we first validate our dimensional analysis with two-dimensional thermo- kinematical models: for typical values and scenarios applicable to different thrusts, our numerical results show specific thermal evolutions. Then, we apply our first-order coupled analytical-numerical method to natural occurrences of inverted zonation of metamorphic peak temperatures. In this way, our analysis suggests that the inverted metamorphism associated to the Main Central Thrust in the Himalayas, for instance, can be mainly a result of shear heating.

Duprat-Oualid, Sylvia; Yamato, Philippe; Schmalholz, Stefan M.

2014-05-01

102

Radiation transfer thrusters for low thrust applications  

Energy Technology Data Exchange (ETDEWEB)

A thruster assembly for low thrust applications and use with a propellant which may be heated in order to obtain a higher specific impulse which increases the life of a propulsion system, the thruster assembly is described comprising: (a) a heating filament and power source controllably connected thereto; (b) a heater cavity having heater walls having an inner surface; (c) a supporting structure for the heating filament; (d) a propellant guiding structure surrounding the heater cavity and having at least one propellant passageway therein; (e) the propellant guiding structure being further constructed to permit sufficient heat to be transferred to the fluid in order to enable the fluid to be used as a propellant and in the manner obtain a higher specific impulse at times when the filaments is switched off.

Cann, G.L.

1988-03-15

103

The experimental study on efficiency improvement of turbo machinery supported with magnetic bearings  

International Nuclear Information System (INIS)

To implement a conventional electromagnetic bearing in small turbo machinery, it has problems such as load capacity and size. Therefore, in this paper, these problems are resolved by using a permanent magnet biased electromagnetic bearing as a thrust bearing of small turbo machinery. Because the flux path of the bearing is designed by reluctance path modulation using an electromagnet and a permanent magnet, the bearing improves upon non-linearity, power consumption, size and load capacity of a conventional electromagnetic bearing. Test rotating the shaft over 500,000DN were carried out to verify the performance of the proposed small turbo machinery. In addition, the relationships between mass flow rate and pressure rise were measured as changing the tip clearance to verify the feasibility of efficiency improvement and active surge control and these results were compared with theoretical results

2007-11-02

104

Unsteady thrust force under repture of pipeline containing hot water  

International Nuclear Information System (INIS)

Unsteady thrust force during simmering water leakage after transverse rupture of a pipeline 12 mm in diameter is measured. Results of experiments are satisfactorily described with calculation in the assumption of leakage homogeneity and equilibrium. Consideration of the process unstationarity permits to decrease considerably the designed thrust force for NPPs with WWER reactors

1986-07-01

105

Impact of plasma noise on a direct thrust measurement system  

Science.gov (United States)

In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agreement for static mass calibrations and validation with a cold gas thruster. However, the data obtained using the LVDT deviate significantly from that of the laser sensor when operating two varieties of plasma thrusters: a radio frequency (RF) driven plasma thruster, and a DC powered plasma thruster. Results establish that even with appropriate shielding and signal filtering the LVDT sensor is subject to plasma noise and radio frequency interactions which result in anomalous thrust readings. Experimental data show that the thrust determined using the LVDT system in a direct current plasma environment and a RF discharge is approximately a factor of three higher than the thrust values obtained using a laser sensor system for the operating conditions investigated. These findings are of significance to the electric propulsion community as LVDT sensors are often utilized in thrust measurement systems and accurate thrust measurement and the reproducibility of thrust data is key to analyzing thruster performance. Methods are proposed to evaluate system susceptibility to plasma noise and an effective filtering scheme presented for DC discharges.

Pottinger, S. J.; Lamprou, D.; Knoll, A. K.; Lappas, V. J.

2012-03-01

106

Tarp rotor system thrust, yaw and load control  

Energy Technology Data Exchange (ETDEWEB)

Presented is a means for thrust and, hence, yaw and load control of a TARP twin rotor system by means of initiating a thrust differential between said rotors which, in turn, yaws the twin rotor assembly into a protected low flow velocity region about a TARP and alleviates load on said assembly.

Weisbrich, A. L.

1985-09-10

107

Electronics Engineering Department Thrust Area report FY'84  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1984-01-01

108

Electronics Engineering Department Thrust Area report FY'84  

International Nuclear Information System (INIS)

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

1984-01-01

109

Bear Spray Safety Program  

Science.gov (United States)

A bear spray safety program for the U.S. Geological Survey (USGS) was officially initiated by the Firearms Safety Committee to address accident prevention and to promote personnel training in bear spray and its transportation, storage, and use for defense against wild animals. Used as part of a system including firearms, or used alone for those who choose not to carry a firearm, bear spray is recognized as an effective tool that can prevent injury in a wild animal attack.

Blome, C. D.; Kuzniar, R. L.

2009-01-01

110

Bearing restoration by grinding  

Science.gov (United States)

A joint program was undertaken by the NASA Lewis Research Center and the Army Aviation Systems Command to restore by grinding those rolling-element bearings which are currently being discarded at aircraft engine and transmission overhaul. Three bearing types were selected from the UH-1 helicopter engine (T-53) and transmission for the pilot program. No bearing failures occurred related to the restoration by grinding process. The risk and cost of a bearing restoration by grinding programs was analyzed. A microeconomic impact analysis was performed.

Hanau, H.; Parker, R. J.; Zaretsky, E. V.; Chen, S. M.; Bull, H. L.

1976-01-01

111

Polar bears at risk  

Energy Technology Data Exchange (ETDEWEB)

Polar bears, the world's largest terrestrial carnivore, spend much of their lives on the arctic sea ice. This is where they hunt and move between feeding, denning, and resting areas. The world population, estimated at 22,000 bears, is made up of 20 relatively distinct populations varying in size from a few hundred to a few thousand animals. About 60 per cent of all polar bears are found in Canada. In general, the status of this species is stable, although there are pronounced differences between populations. Reductions in the extent and thickness of sea ice has lead the IUCN Polar Bear Specialist Group to describe climate change as one of the major threats facing polar bears today. Though the long-term effects of climate change will vary in different areas of the Arctic, impacts on the condition and reproductive success of polar bears and their prey are likely to be negative. Longer ice-free periods resulting from earlier break-up of sea ice in the spring and later formation in the fall is already impacting polar bears in the southern portions of their range. In Canada's Hudson Bay, for example, bears hunt on the ice through the winter and into early summer, after which the ice melts completely, forcing bears ashore to fast on stored fat until freeze-up in the fall. The time bears have on the ice to hunt and build up their body condition is cut short when the ice melts early. Studies from Hudson Bay show that for every week earlier that ice break-up occurs, bears will come ashore 10 kg lighter and in poorer condition. It is likely that populations of polar bears dividing their time between land and sea will be severely reduced and local extinctions may occur as greenhouse gas emissions continue to rise and sea ice melts. Expected changes in regional weather patterns will also impact polar bears. Rain in the late winter can cause maternity dens to collapse before females and cubs have departed, thus exposing occupants to the elements and to predators. Such rains also destroy the denning habitat of ringed seals, the polar bears' primary prey. Declines in the ringed seal population would mean a loss of food for polar bears. A trend toward stronger winds and increasing ice drift observed in some parts of the Arctic over the last five decades will likely increase energy expenditures and stress levels in polar bears that spend most of their lives on drifting sea ice. Polar bears face other limiting factors as well. Historically, the main threat to polar bears has been hunting. Satisfactory monitoring information has been obtained for most polar bear populations in recent years, however there is concern about hunting in areas without formal quota systems, such as Greenland. A range of toxic pollutants, including heavy metals, radioactivity, and persistent organic pollutants (POPs) are found throughout the Arctic. Of greatest concern are the effects of POPs on polar bears, which include a general weakening of the immune system, reduced reproductive success and physical deformities. The expansion of oil development in the Arctic poses additional threats; for example, disturbances to denning females in the Arctic National Wildlife Refuge in Alaska could undermine recruitment of the Beaufort Sea polar bear population. These threats, along with other effects of human activity in the Arctic, combine to pressure polar bears and their habitat. Large carnivores are sensitive indicators of ecosystem health and can be used to define the minimum area necessary to preserve intact ecosystems. WWF has identified the polar bear as a unique symbol of the complexities and interdependencies of the arctic marine ecosystem as it works toward its goal of preserving biodiversity for future generations.

Norris, S.; Rosentrater, L.; Eid, P.M. [WWF International Arctic Programme, Oslo (Norway)

2002-05-01

112

Large-bore tapered-roller bearing performance and endurance to 2.4 million DN  

Science.gov (United States)

The operating characteristics and experimental life estimates for 120.65 mm bore tapered roller bearings of two designs under combined radial and thrust loads were determined. A modified standard bearing design was tested at speeds up to 15,000 rpm. A computer optimized, high speed design was tested at speeds up to 20,000 rpm. Both designs were tested at a combined load of 26,700 N (6000 lb) radial load and and 53,400 N (12,000 lb) thrust load. Advanced helicopter transmissions which require the higher-speed capability of tapered-roller bearings also require higher temperature capability (ref. 2). Thus, materials with temperature capabilities higher than the conventional carburizing steels are required.

Parker, R. J.

1983-01-01

113

Frequency of Varus and Valgus Thrust and Factors Associated with Thrust Presence in Persons With or at Higher Risk for Knee Osteoarthritis  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Varus thrust observed during gait has been shown to be associated with a 4-fold increase in the risk of medial knee osteoarthritis progression. Valgus thrust is believed less common than varus thrust; the prevalence of each is uncertain. Racial differences in risk factors may help explain variations in the natural history of knee osteoarthritis. Our objectives were: determine the frequency of varus and valgus thrust in African-Americans and Caucasians; identify factors associated with thrust ...

Chang, Alison; Hochberg, Marc; Song, Jing; Dunlop, Dorothy; Chmiel, Joan S.; Nevit, Michael; Hayes, Karen; Eaton, Charles; Bathon, Joan; Jackson, Rebecca; Kwoh, Kent; Sharma, Leena

2010-01-01

114

Bearing shrinkage fitting device. Bearing yakibame sochi  

Energy Technology Data Exchange (ETDEWEB)

This paper introduces a bearing shrinkage fitting device to fit rollers and shaft washers by inductively heating directly the outer bearing rings. The equipment features include the capability of establishing the heating condition by work piece only by selecting an inductive heating coil, and the requirement of less amount of inputting and moving work for heavy items which expands the scope of work pieces to be handled. The device enables quick starting by means of a high-frequency two-step inductive heating system, fast and uniform heating by the use of only small amount of power, and facilitates power saving and automation as a result of electrical control. The device improves working environments, enables setting the optimal fitting temperature condition, and improves the workability through use of the automatic roller fitting mechanism. Further, the residual magnetism is as low as less than 5 gausses, and the setup time is as short as about six minutes. The heating coil for a keystone bearing uses a water cooled multi-turn, and the matching circuit uses a matching transformer, with the matching carried out only by adjusting the capacitors. The heating coil for an angular bearing uses both water cooled one-turn and multi-turn, with the matching section disposed with a matching transformer, and the matching circuit using transformer taps and capacitors. 9 figs., 1 tab.

Nakamura, M.; Katanosaka, T.; Masuda, O. (Meidensha Corp., Tokyo (Japan))

1991-12-27

115

High efficiency thrust vector control allocation  

Science.gov (United States)

The design of control mixing algorithms for launch vehicles with multiple vectoring engines yields competing objectives for which no straightforward solution approach exists. The designer seeks to optimally allocate the effector degrees of freedom such that maneuvering capability is maximized subject to constraints on available control authority. In the present application, such algorithms are generally restricted to linear transformations so as to minimize adverse control-structure interaction and maintain compatibility with industry-standard methods for control gain design and stability analysis. Based on the application of the theory of ellipsoids, a complete, scalable, and extensible framework is developed to effect rapid analysis of launch vehicle capability. Furthermore, a control allocation scheme is proposed that simultaneously balances attainment of the maximum maneuvering capability with rejection of internal loads and performance losses resulting from thrust vectoring in the null region of the admissible controls. This novel approach leverages an optimal parametrization of the weighted least squares generalized inverse and exploits the analytic properties of the constraint geometry so as to enable recovery of more than ninety percent of the theoretical capability while maintaining linearity over the majority of the attainable set.

Orr, Jeb S.

116

Effect of cage design on characteristics of high-speed-jet-lubricated 35-millimeter-bore ball bearing. [turbojet engines  

Science.gov (United States)

Parametric tests were conducted with a 35 mm bore angular contact ball bearing with a double outer land guided cage. Provisions were made for jet lubrication and outer-ring cooling of the bearing. Test conditions included a combined thrust and radial load at nominal shaft speeds of 48,000 rpm, and an oil-in temperature of 394 K (250 F). Successful operation of the test bearing was accomplished up to 2.5 million DN. Test results were compared with those obtained with similar bearing having a single outer land guided cage. Higher temperatures were generated with the double outer land guided cage bearing, and bearing power loss and cage slip were greater. Cooling the outer ring resulted in a decrease in overall bearing operating temperature.

Schuller, F. T.; Pinel, S. I.; Signer, H. R.

1980-01-01

117

Thrust Balance Characterization of a 200W Quad Confinement Thruster for High Thrust Regimes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A thrust balance characterization of a low powered Quad Confinement Thruster is presented for high levels of propellant flow. The nominal flow rate for this device is between 1sccm and 2sccm of Xenon propellant. This study extends the operating range, and investigates the performance at two high flow conditions of 10sccm and 20sccm. Power is varied incrementally between 20W and 200W in order to characterize the performance versus power trends of the device. It was found that for these high fl...

Knoll, Ak; Lamprou, D.; Lappas, V.; Pollard, M.; Bianco, P.

2013-01-01

118

Geometric and kinematic evolution of asymmetric ductile shear zones in thrust sheets, southern Adelaide Fold Thrust Belt, South Australia  

Science.gov (United States)

The Southern Adelaide Fold-Thrust Belt, South Australia contains unusually asymmetric shallow to moderately inclined low-grade phyllonitic shear zones, uniformly floored by basal imbricate thrusts. The fabrics and minor structures that reveal the geometric and kinematic evolution of these shear zones are described, analysed and presented in detail. Incipient fabrics and structures are developed in upper transitional zones and then develop progressively more intensely downwards into the shear zones. They ultimately intensify along the lower boundary thrusts that make up the base of all of the shear zones. Microstructural analysis of multiple cleavages and grain-scale geometries from within the shear zones demonstrate that deformation is spatially and temporally concentrated along the lower boundary thrusts. The shear zones initiated by strain-softening at the base of a number of stacked thrust sheets during Mid- to Late-Cambrian orogenic shortening of the area when the fold-thrust belt was generated. Kinematic indicators confirm consistent NW-directed transport. The shear zones progressively developed upwards by further superposition of shear and flattening strain during which time deformation was localised within the base of the thrust sheets to develop distinctively asymmetric shear zones.

Yassaghi, A.; James, P. R.; Flottmann, T.

2000-07-01

119

Field and Experimental investigation of the Frictional Behaviour of mechanically heterogeneous thrusts  

Science.gov (United States)

Recent high-resolution geodetic and seismological data reveal that tectonic faults exhibit complex, multi-mode slip behavior including earthquakes, creep events, slow and silent earthquakes, low-frequency events and earthquake afterslip. Here we have studied three large-displacement (5-10 km) thrust faults from the Northern Apennines (Central Italy), in the field and in the lab to address the influence of different lithologies (carbonates and marls) on fault zone structure and mechanics. We observe a full spectrum of fault architectures ranging from localized brittle faulting in massive limestones to wide (up to 200 m) ductile shear zones in marly limestones and marls. Brittle shear zones present abundant cataclasites, ultractaclasites, fault mirrors and structures diagnostic of seismically induced dehydration and decarbonation. On the other hand, ductile shear zones present S-CC' tectonites formed by pressure solution and frictional sliding. This evidence suggests strong differences in strength and slip behaviour (seismic vs non-seismic) of the different fault zones. To quantitatively test this hypothesis we carried out experiments on these natural fault rocks. We sheared both intact wafers and powdered fault materials applying low (10 MPa) and in-situ (53 MPa) normal stress under water-saturated conditions. We used velocity steps (1 to 300 ?m/s) and slide-hold-slide (3-1000 s holds) to assess the frictional stability and healing behaviour of our rocks. Mechanical results quantitatively support the idea of heterogeneous thrust faults where strong and seismogenic fault portions coexist with weak fault patches that are prone to slow sliding. The characterization of the interaction between heterogeneous fault patches in both time and space is vital for assessing the seismogenic potential of places like Northern Italy where carbonate-bearing thrusts are present at seismogenic depth.

Tesei, T.; Collettini, C.; Di Stefano, G.

2013-12-01

120

Measuring Bearing-Cage Rotation  

Science.gov (United States)

Bearing slip measured optically. Concept for measuring rotational speed of bearing cage promises to be simple and accurate. Based on fiber optics, requires no contact between measuring device and bearing, and would not introduce wear.

Roschak, E. J.

1987-01-01

 
 
 
 
121

Ball and Roller Bearings. A Teaching Reference.  

Science.gov (United States)

The manual provides a subject reference for ball and roller bearings. The following topics are included: (1) bearing nomenclature, (2) bearing uses, (3) bearing capacities, (4) shop area working conditions, (5) bearing removal, (6) bearing cleaning and inspection, (7) bearing replacement, (8) bearing lubrication, (9) bearing installation, (10)…

American Association for Vocational Instructional Materials, Athens, GA.

122

Magnetic bearing update  

Energy Technology Data Exchange (ETDEWEB)

Stabilization of whirl instability by floppy, viscous bearing mounts is discussed and required material properties are estimated for the new tilt-whirl mode in eddy-current stabilized magnetic bearings. A relatively low Young`s modules Y {approximately} 10{sup 5} and high viscosity {zeta} {approximately} 10{sup 7} are required (both in MKS units), suggesting the need for careful mounting design. New information on periodic bearings shows that, thus far, Earshaw`s Theorem cannot be defeated by periodicity, despite the author`s earlier claims.

Fowler, T.K.

1995-05-25

123

Search for unconventional methane resources beneath crystalline thrust sheets in the southern Appalachians  

Energy Technology Data Exchange (ETDEWEB)

The crystalline rocks of the Virginia Blue Ridge and Piedmont provinces are generally not thought to be likely targets for natural gas exploration. However, recent fluid inclusion studies have documented the presence of methane in post-Alleghanian quartz veins in the Blue Ridge and Piedmont. Methane is not a stable component of the COH fluid phase predicted to be in equilibrium with these rocks at the P-T conditions of metamorphism. This suggests that the methane is not generated locally but, rather, is derived from other sources. Sedimentary rocks equivalent to the productive hydrocarbon Devonian shale beds of the Appalachian Basin are present in surficial tectonic slices on the Reed Mountain and Coyner Mountain structures in the roanoke area, and Devonian shale source beds are thought to exist beneath the Pulaski and Blue Ridge thrust sheets to the southeast. These source beds are part of the hydrocarbon-bearing Lower Paleozoic shelf strata that are interpreted to be buried beneath the crystalline thrust sheets in the Southern Appalachians.

Olsen, K.; Costain, J.K.; Bodnar, R.J.; Coruh, C. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States). Dept. of Geological Sciences); Henika, W.S.

1994-03-01

124

Development of Sputtered Techniques for Thrust Chambers, Task 1.  

Science.gov (United States)

Filler materials proposed for use in the sputter fabrication regeneratively cooled thrust chambers were evaluated. Low melting castable alloys, CERROBEND. CERROCAST, and CERROTRU, slurry applied SERMETEL 481 and flame-sprayed aluminum were investigated as...

J. R. Mullaly T. E. Schmid R. J. Hecht

1974-01-01

125

Thrust control in supersonic flight by external burning  

Energy Technology Data Exchange (ETDEWEB)

Control of the thrust and thrust vector angle is difficult for reuseable space transportation systems, when SERN-nozzles are used. In this paper the influence of external burning of hydrogen on the thrust and on the thrust vector angle for the research configuration ELAC 1 is investigated. The Navier-Stokes equations for viscous, compressible, reactive flows are solved. The mixture composition is calculated with the assumption of chemical equilibrium. The conservation equations are discretized on blockstructured, curvilinear grids with second-order accuracy. The resulting system of linear algebraic equations is solved with an alternating line-relaxation method. Results are presented for a free stream Mach number of Ma[sub [infinity

Kropp, M.; Henze, A. (Technische Hochschule Aachen (Germany). Lehrstuhl fuer Stroemungslehre und Aerodynamisches Inst.)

1999-01-01

126

Thrust engine and propellant exhaust arrangement therefor  

Energy Technology Data Exchange (ETDEWEB)

A nuclear engine and nozzle arrangement are described for a nuclear rocket comprising a cluster of elongated fissile fuel bearing and high temperature capacity modules suitably supported in a pressure vessel. The modules have a plurality of coolant-propellant channels extending therethrough, a convergent - divergent nozzle structure of fixed cross-sectional dimensions secured to the end portion of each of said modules, a divergent-only unitary skirt member connected directly to the propellant exit end of said modular cluster in series with and diverging from the divergent ends of said convergent-divergent nozzle structures. The modules are formed to conduct a compressible propellant therethrough at sub-sonic velocities, said nozzle structures being formed to develop supersonic velocities of the propellant and said divergent-only skirt being formed to develop further the supersonic velocities of said propellant.

Retallick, F.D.

1981-01-27

127

Anomalous Thrust Production from an RF Test Device Measured on a Low-Thrust Torsion Pendulum  

Science.gov (United States)

This paper describes the eight-day August 2013 test campaign designed to investigate and demonstrate viability of using classical magnetoplasmadynamics to obtain a propulsive momentum transfer via the quantum vacuum virtual plasma. This paper will not address the physics of the quantum vacuum plasma thruster, but instead will describe the test integration, test operations, and the results obtained from the test campaign. Approximately 30-50 micro-Newtons of thrust were recorded from an electric propulsion test article consisting primarily of a radio frequency (RF) resonant cavity excited at approximately 935 megahertz. Testing was performed on a low-thrust torsion pendulum that is capable of detecting force at a single-digit micronewton level, within a stainless steel vacuum chamber with the door closed but at ambient atmospheric pressure. Several different test configurations were used, including two different test articles as well as a reversal of the test article orientation. In addition, the test article was replaced by an RF load to verify that the force was not being generated by effects not associated with the test article. The two test articles were designed by Cannae LLC of Doylestown, Pennsylvania. The torsion pendulum was designed, built, and operated by Eagleworks Laboratories at the NASA Johnson Space Center of Houston, Texas. Approximately six days of test integration were required, followed by two days of test operations, during which, technical issues were discovered and resolved. Integration of the two test articles and their supporting equipment was performed in an iterative fashion between the test bench and the vacuum chamber. In other words, the test article was tested on the bench, then moved to the chamber, then moved back as needed to resolve issues. Manual frequency control was required throughout the test. Thrust was observed on both test articles, even though one of the test articles was designed with the expectation that it would not produce thrust. Specifically, one test article contained internal physical modifications that were designed to produce thrust, while the other did not (with the latter being referred to as the "null" test article). Test data gathered includes torsion pendulum displacement measurements which are used to calculate generated force, still imagery in the visible spectrum to document the physical configuration, still imagery in the infrared spectrum to characterize the thermal environment, and video imagery. Post-test data includes static and animated graphics produced during RF resonant cavity characterization using the COMSOL Multiphysics® software application. Excerpts from all of the above are included and discussed in this paper. Lessons learned from test integration and operations include identification of the need to replace manual control of the resonant cavity target frequency with an automated frequency control capability. Future test plans include the development of an automatic frequency control circuit. Test results indicate that the RF resonant cavity thruster design, which is unique as an electric propulsion device, is producing a force that is not attributable to any classical electromagnetic phenomenon and therefore is potentially demonstrating an interaction with the quantum vacuum virtual plasma. Future test plans include independent verification and validation at other test facilities.

Brady, David; White, Harold G.; March, Paul; Lawrence, James T.; Davies, Frank J.

2014-01-01

128

Dynamic Visual Acuity during Passive Head Thrusts in Canal Planes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We sought to determine whether the dynamic visual acuity (DVA) test, which has been used to measure the function of the two horizontal semicircular canals (SCCs), could be adapted to measure the individual function of all six SCCs using transient, rapid, unpredictable head rotation stimuli (head thrusts) in the direction of maximum sensitivity of each SCC. We examined head-thrust DVA (htDVA) performance in 19 healthy control subjects, five patients before and six patients after plugging of on...

2006-01-01

129

Static test of a large scale swivel nozzle thrust deflector  

Science.gov (United States)

Experimental results from a swivel nozzle thrust deflector test program are presented. The deflector was installed behind a 36-inch fan with a tip turbine hot gas drive. The maximum nozzle pressure ratio was 1.2. Nozzle thrust and flow coefficients are presented for a range of vectoring angles. The results are also compared to small scale cold flow test results. The comparison suggests a need for accurate simulation of nozzle entry pressure and temperature profiles on model tests.

Federspiel, J. F.

1979-01-01

130

Thrust distributions and decays of the UPSILON bound states  

International Nuclear Information System (INIS)

We have studied the topologies of hadronic events in e"+e"- annihilation data taken in the region of the upsilon resonances with the non-magnetic CUSB detector at CESR. Using thrust-like variable we compare the decays of tau, tau' and tau'', and find for tau'' a significant excess of high thrust events, which we interpret as evidence for electric dipole transitions. (orig.)

1982-07-29

131

Acoustically shielded exhaust system for high thrust jet engines  

Science.gov (United States)

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.

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

1995-01-01

132

Fracturing stages in foreland fold and thrust belts  

Science.gov (United States)

Many of the most prolific hydrocarbon systems of the world are hosted in foreland fold and thrust belts, where oil migration is frequently ensured by the sub-seismic fracture network and oil accumulation occurs in km-scale anticlines associated with major thrust-faults. The existence of this well known hydrocarbon play, were oil fields development requires reconstructing the deformation pattern at depth, is one of the reasons that have promoted an impressive number of meso-structural studies in foreland fold and thrust belts and in the adjacent foreland basins since the late 60's. These works point out that thrust-related anticlines are characterised by almost unique deformation patterns out of which a common deformation pathway can be identified. In particular, in most thrust belts developing above subducting forelands, five stages of deformation can be recorded by meso-structures affecting pre- and syn-kinematic sedimentary rocks. These stages are: (i) foreland flexuring, taking place in the peripheral bulge and in the outermost sectors of the foredeep; (ii) along-strike stretching, occurring in the foredeep; (iii) layer-parallel shortening, which may occur both in the innermost sectors of the foredeep and in the thrust-and fold belt during the first stages of fold growth (pre to early-folding); (iv) syn-folding sensu-stricto fracturing, occurring during the growth of thrust-related anticlines; (v) unloading-related fracturing, which affects mostly mountain front anticlines during their later exhumation stage. In this work we provide a review of the typical meso-structural assemblages occurring during the above mentioned deformation stages, with the purpose of placing constraints to stress and strain fields evolution before and during thrusting, and consider the behaviour of each developed meso-structural assemblage during the subsequent deformation stages.

Tavani, Stefano; Storti, Fabrizio; Lacombe, Olivier; Corradetti, Amerigo; Muñoz, Josep; Mazzoli, Stefano

2014-05-01

133

Bilateral and multiple cavitation sounds during upper cervical thrust manipulation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Background The popping produced during high-velocity, low-amplitude (HVLA) thrust manipulation is a common sound; however to our knowledge, no study has previously investigated the location of cavitation sounds during manipulation of the upper cervical spine. The primary purpose was to determine which side of the spine cavitates during C1-2 rotatory HVLA thrust manipulation. Secondary aims were to calculate the average number of pops, the duration of upper cervical t...

Dunning James; Mourad Firas; Barbero Marco; Leoni Diego; Cescon Corrado; Butts Raymond

2013-01-01

134

Reevaluation of Late Mesozoic thrusting in east-central Nevada  

Energy Technology Data Exchange (ETDEWEB)

Late Mesozoic thrust faults occur along a narrow, north-south-trending belt through east-central Nevada. The low-angle faults juxtapose older miogeoclinal Paleozoic rocks onto younger miogeoclinal Paleozoic rocks. The thrust belt can be clearly delineated as far north as the northern Diamond Range and as far south as northwestern Clark County, where the structure merge with the Sevier overthrust belt of southern Nevada and central Utah. In the northern part of the thrust belt, the depositional relationships of the Newark Canyon formation clearly indicate faulting and attendant folding of Early Cretaceous age. Similarly, the areal relationships of an unnamed Cretaceous-early Tertiary(.) conglomeratic unit in the southern part of the belt suggests a Cretaceous and possibly younger age for deformation there. The thrusting has effectively telescoped the Mississippian Antler basin, as the Mississippian Chainman Shale is consistently the surface of decollement of the structurally lowest exposed thrust. This relationship is important for hydrocarbon exploration as the Chainman is the likely source of oil in the east-central Nevada oil fields. All of these fields lie within the delineated thrust belt. The exact structural relationship between the east-central Nevada thrust belt and the similar-age Sevier overthrust belt of Utah has yet to be worked out, but it is suggested that prior to middle Tertiary extension, these belts lay side by side, delineating a northeast-trending belt of deformation. Differential Tertiary extension has displaced the hinterland of the thrust belt in a direction counterclockwise from its original position. An estimated 160 km of extension occurred at the latitude of Ely, Nevada.

Cameron, G.J.; Chamberlain, A.K.

1987-05-01

135

Impact of plasma noise on a direct thrust measurement system  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In order to evaluate the accuracy and sensitivity of a pendulum-type thrust measurement system, a linear variable differential transformer (LVDT) and a laser optical displacement sensor have been used simultaneously to determine the displacement resulting from an applied thrust. The LVDT sensor uses an analog interface, whereas the laser sensor uses a digital interface to communicate the displacement readings to the data acquisition equipment. The data collected by both sensors show good agre...

Pottinger, S. J.; Lamprou, D.; Knoll, A. K.; Lappas, V. J.

2012-01-01

136

Thrust enhancement of the gasdynamic mirror (GDM) fusion propulsion system  

Science.gov (United States)

The gasdynamic mirror propulsion system is a device that utilizes a magnetic mirror configuration to confine a hot plasma to allow fusion reactions to take place while ejecting a fraction of the energetic charged particles through one end to generate thrust. Because the fusion fuel is generally an isotope of hydrogen, e.g., deuterium or tritium, this propulsion device is capable of producing very large specific impulses (e.g., 200,000 seconds) but at modest thrusts. Since large thrusts are desirable, not only for reducing travel time but also for lifting sizable payloads, we have examined methods by which GDM's thrust could be enhanced. The first consists of utilizing the radiation generated by the plasma, namely bremsstrahlung and synchrotron radiation, to heat a hydrogen propellant which upon exhausting through a nozzle produces the additional thrust. We asses the performance in this case by using an ideal model that ignores heat transfer considerations of the chamber wall, and one that takes into account heat flow and wall temperature limitations. We find in the case of a DT burning plasma that although thrust enhancement is significant, it was more than offset by the large drop in the specific impulse and a concomitant increase in travel time. The second method consisted of not altering the original GDM operation, but simply increasing the density of the injected plasma to achieve higher thrust. It is shown that the latter approach is more effective since it is compatible with improved performance in that it reduces trip time but at the expense of larger vehicle mass. For a D-He3 burning device the use of hydrogen to enhance thrust appears to be more desirable since the radiated power that goes into heating the hydrogen propellant is quite large.

Kammash, Terry; Lee, Myoung-Jae; Poston, David I.

1997-01-01

137

Thrust enhancement of the gasdynamic mirror (GDM) fusion propulsion system  

International Nuclear Information System (INIS)

The gasdynamic mirror propulsion system is a device that utilizes a magnetic mirror configuration to confine a hot plasma to allow fusion reactions to take place while ejecting a fraction of the energetic charged particles through one end to generate thrust. Because the fusion fuel is generally an isotope of hydrogen, e.g., deuterium or tritium, this propulsion device is capable of producing very large specific impulses (e.g., 200,000 seconds) but at modest thrusts. Since large thrusts are desirable, not only for reducing travel time but also for lifting sizable payloads, we have examined methods by which GDM's thrust could be enhanced. The first consists of utilizing the radiation generated by the plasma, namely bremsstrahlung and synchrotron radiation, to heat a hydrogen propellant which upon exhausting through a nozzle produces the additional thrust. We asses the performance in this case by using an ideal model that ignores heat transfer considerations of the chamber wall, and one that takes into account heat flow and wall temperature limitations. We find in the case of a DT burning plasma that although thrust enhancement is significant, it was more than offset by the large drop in the specific impulse and a concomitant increase in travel time. The second method consisted of not altering the original GDM operation, but simply increasing the density of the injected plasma to achieve higher thrust. It is shown that the latter approach is more effective since it is compatible with improved performance in that it reduces trip time but at the expense of larger vehicle mass. For a D-He3 burning device the use of hydrogen to enhance thrust appears to be more desirable since the radiated power that goes into heating the hydrogen propellant is quite large

1997-01-10

138

PCs and Polar Bears  

Science.gov (United States)

This article looks at the growing energy consumption from consumer electronics and the increases it may cause in greenhouse gases and global warming. The article appears in the free, online magazine Beyond Penguins and Polar Bears.

Fries-Gaither, Jessica

2011-01-01

139

Magnetic Bearing System.  

Science.gov (United States)

A magnetic bearing system is described which includes a high magnetic permeability interior disc member that is symmetrical about a longitudinal z axis. An annular member of high magnetic permeability is coaxial with and surrounds the disc, but is mechani...

P. A. Studer

1975-01-01

140

Thrust vector control of satellites using smart parallel manipulators  

Science.gov (United States)

This paper presents the concept, control strategy, and simulations of thrust vector control of satellites. First, an innovative thrust vector control concept is introduced, which utilizes the UHM multifunctional smart parallel manipulator to provide precision position control of the thruster vector and vibration suppression capability while the thruster fires. The configuration of the thrust vector control system is then illustrated, and the satellite attitude dynamic model is built. Third, the UHM smart parallel manipulator is introduced and its kinematics and controller design are discussed. The fuzzy logic controller is employed to precisely position the smart parallel manipulator and to compensate the non-linearities due to the friction and backlash of the actuators and the tolerance of the joints. Finally, the satellite attitude controller and the fuzzy logic controller are designed, and simulations are carried out to realize the thrust vector control of a satellite. The results indicate that the smart parallel manipulator can precisely achieve the thrust vector control, the misalignment of the trust vector of the satellite can be corrected effectively, and the position accuracy of the thrust vector is 0.68 arc minutes.

Ma, Kougen; Ghasemi-Nejhad, Mehrdad N.

2006-04-01

 
 
 
 
141

Gear bearing drive  

Science.gov (United States)

A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

2011-01-01

142

High Speed Operation and Testing of a Fault Tolerant Magnetic Bearing  

Science.gov (United States)

Research activities undertaken to upgrade the fault-tolerant facility, continue testing high-speed fault-tolerant operation, and assist in the commission of the high temperature (1000 degrees F) thrust magnetic bearing as described. The fault-tolerant magnetic bearing test facility was upgraded to operate to 40,000 RPM. The necessary upgrades included new state-of-the art position sensors with high frequency modulation and new power edge filtering of amplifier outputs. A comparison study of the new sensors and the previous system was done as well as a noise assessment of the sensor-to-controller signals. Also a comparison study of power edge filtering for amplifier-to-actuator signals was done; this information is valuable for all position sensing and motor actuation applications. After these facility upgrades were completed, the rig is believed to have capabilities for 40,000 RPM operation, though this has yet to be demonstrated. Other upgrades included verification and upgrading of safety shielding, and upgrading control algorithms. The rig will now also be used to demonstrate motoring capabilities and control algorithms are in the process of being created. Recently an extreme temperature thrust magnetic bearing was designed from the ground up. The thrust bearing was designed to fit within the existing high temperature facility. The retrofit began near the end of the summer, 04, and continues currently. Contract staff authored a NASA-TM entitled "An Overview of Magnetic Bearing Technology for Gas Turbine Engines", containing a compilation of bearing data as it pertains to operation in the regime of the gas turbine engine and a presentation of how magnetic bearings can become a viable candidate for use in future engine technology.

DeWitt, Kenneth; Clark, Daniel

2004-01-01

143

Strain path partitioning within thrust sheets: microstructural and petrofabric evidence from the Moine Thrust zone at Loch Eriboll, northwest Scotland  

Science.gov (United States)

Quartz c axis fabrics and microstructures have been investigated within a suite of quartzites collected from the Loch Eriboll area of the Moine Thrust zone and are used to interpret the detailed processes involved in fabric evolution. The intensity of quartz c axis fabrics is directly proportional to the calculated strain magnitude. A correlation is also established between the pattern of c axis fabrics and the calculated strain symmetry. Two kinematic domains are recognized within one of the studied thrust sheets which outcrops immediately beneath the Moine Thrust. Within the upper and central levels of the thrust sheet coaxial deformation is indicated by conjugate, mutually interfering shear bands, globular low strain detrital quartz grains whose c axes are aligned sub-parallel to the principal finite shortening direction ( Z) and quartz c axis fabrics which are symmetric (both in terms of skeletal outline and intensity distribution) with respect to mylonitic foliation and lineation. Non-coaxial deformation is indicated within the more intensely deformed and recrystallized quartzites located near the base of the thrust sheet by single sets of shear bands and c axis fabrics which are asymmetric with respect to foliation and lineation. Tectonic models offering possible explanations for the presence of kinematic (strain path) domains within thrust sheets are considered.

Law, R. D.; Knipe, R. J.; Dayan, H.

144

Electromagnetic launch, then lessening chemical thrust over time as laser beam powered ion thrust grows{emdash}to any orbit  

Energy Technology Data Exchange (ETDEWEB)

The ElectroMagnetic (EM) Launch Tube (LT), using High-Temp SuperConduction (HTSC) EM launch coils if developed, will be built in a tall building, or, if not, at a steep angle up the west slope of an extinct volcano. The Reusable Launch Vehicle (RLV) exits the LT at such high velocity that the otherwise violent entry into the atmosphere is made possible by Special-Laser-Launch-Assist (SLLA), which ionizes and expands the atmosphere immediately ahead of the RLV. At first a brief period of chemical thrust is followed by a long period of ion thrust during ascent to orbit. As decades pass and greater ion thrust is developed, the period of chemical thrust shortens until it is no longer needed. The RLV{close_quote}s ion thrusters are powered by laser/maser, beamed first from the launch site, then from two large Solar-Power-Satellites (SPS) 180{degree} apart in Medium Earth Orbit (MEO) orbit. In orbit, the RLV is limited in where it can go only by the amount of propellant it carries or is stored in various orbits. The RLV can land at a launch site on Earth by using both chemical and ion thrust at first, and later by ion thrust alone as developments cause a far lighter RLV to carry no chemical engines/fuel/tanks. {copyright} {ital 1996 American Institute of Physics.}

Morse, T.M. [AT& T Technologies Planning Engineer (Retired), 334 Lakeview Shores Loop, Mooresville, North Carolina 28115 (United States)

1996-03-01

145

Bilateral and multiple cavitation sounds during upper cervical thrust manipulation  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background The popping produced during high-velocity, low-amplitude (HVLA thrust manipulation is a common sound; however to our knowledge, no study has previously investigated the location of cavitation sounds during manipulation of the upper cervical spine. The primary purpose was to determine which side of the spine cavitates during C1-2 rotatory HVLA thrust manipulation. Secondary aims were to calculate the average number of pops, the duration of upper cervical thrust manipulation, and the duration of a single cavitation. Methods Nineteen asymptomatic participants received two upper cervical thrust manipulations targeting the right and left C1-2 articulation, respectively. Skin mounted microphones were secured bilaterally over the transverse process of C1, and sound wave signals were recorded. Identification of the side, duration, and number of popping sounds were determined by simultaneous analysis of spectrograms with audio feedback using custom software developed in Matlab. Results Bilateral popping sounds were detected in 34 (91.9% of 37 manipulations while unilateral popping sounds were detected in just 3 (8.1% manipulations; that is, cavitation was significantly (P Conclusions Cavitation was significantly more likely to occur bilaterally than unilaterally during upper cervical HVLA thrust manipulation. Most subjects produced 3–4 pops during a single rotatory HVLA thrust manipulation targeting the right or left C1-2 articulation; therefore, practitioners of spinal manipulative therapy should expect multiple popping sounds when performing upper cervical thrust manipulation to the atlanto-axial joint. Furthermore, the traditional manual therapy approach of targeting a single ipsilateral or contralateral facet joint in the upper cervical spine may not be realistic.

Dunning James

2013-01-01

146

Hybrid Superconducting Magnetic Bearing (HSMB) for high-load devices  

International Nuclear Information System (INIS)

Lifting capacities greater than 41 N/cm(exp 2) (60 psi) at 77 K have been achieved with a new type of levitation (hybrid) using a combination of permanent magnets and high quality melt-mixtured YBa2Cu3O(7-delta) (YBCO). The key concept of the hybrid superconducting magnetic bearing (HSMB) is the use of strong magnetic repulsion and attraction from permanent magnets for high levitation or suspension forces in conjunction with a superconductor's flux pinning characteristics to counteract the inherent instabilities in a system consisting of magnets only. To illustrate this concept, radial and axial forces between magnet/superconductor, magnet/magnet, and magnet/superconductor/magnet, were measured and compared for the thrust bearing configuration

1992-05-01

147

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

International Nuclear Information System (INIS)

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

1991-01-01

148

Thrust Characteristics of a Coaxial Laser-Electromagnetic Hybrid Thruster  

Science.gov (United States)

An experimental study on coaxial laser-electromagnetic hybrid thrusters was conducted. The laser-electromagnetic hybrid thruster, consisting of a coaxial electrode configuration with an annular copper anode and carbon fiber rod cathode was used to produce laser-induced plasmas, which were further accelerated by electromagnetic force to improve thrust performance. Experimental measurement of impulse bit and mass shot was conducted. From the measurement, thrust performance showed impulse-bit of 2 ? 45 ?Nsec, momentum coupling coefficient of 5 ? 14 ?Nsec/J, specific impulse of 1000 ? 1400 sec and thrust efficiency of 3 ? 5 % for charge energies 0 ? 8.6 J and a laser pulse energy of 120 mJ. In addition, a significant improvement of thrust performance, could be obtained with the use of alumina propellant, which were an impulse-bit (Ibit) of 60 ?Nsec, a specific impulse (Isp) of 6,000 sec, and a thrust efficiency of 20% at charge energy of 8.6 J.

Horisawa, Hideyuki; Sasaki, Yusuke; Shinohara, Tadaki; Funaki, Ikkoh

149

Design and Operating Characteristics of High-Speed, Small-Bore, Angular-Contact Ball Bearings  

Science.gov (United States)

The computer program SHABERTH was used to analyze 35-mm-bore, angular-contact ball bearings designed and manufactured for high-speed turbomachinery applications. Parametric tests of the bearings were conducted on a high-speed, high-temperature bearing tester and were compared with the computer predictions. Four bearing and cage designs were studied. The bearings were lubricated either by jet lubrication or through the split inner ring with and without outer-ring cooling. The predicted bearing life decreased with increasing speed because of increased operating contact stresses caused by changes in contact angle and centrifugal load. For thrust loads only, the difference in calculated life for the 24 deg. and 30 deg. contact-angle bearings was insignificant. However, for combined loading, the 24 deg. contact-angle bearing gave longer life. For split-inner-ring bearings, optimal operating conditions were obtained with a 24 deg. contact angle and an inner-ring, land-guided cage, using outer-ring cooling in conjunction with low lubricant flow rates. Lower temperature and power losses were obtained with a single-outer-ring, land-guided cage for the 24 deg. contact-angle bearing having a relieved inner ring and partially relieved outer ring. Inner-ring temperatures were independent of lubrication mode and cage design. In comparison with measured values, reasonably good engineering correlation was obtained using the computer program SHABERTH for predicted bearing power loss and for inner- and outer-ring temperatures. The Parker formula for XCAV (used in SHABERTH, a measure of oil volume in the bearing cavity) may need to be refined to reflect bearing lubrication mode, cage design, and location of cage-controlling land.

Pinel, Stanley I.; Signer, Hans R.; Zaretsky, Erwin V.

1998-01-01

150

Partial tooth gear bearings  

Science.gov (United States)

A partial gear bearing including an upper half, comprising peak partial teeth, and a lower, or bottom, half, comprising valley partial teeth. The upper half also has an integrated roller section between each of the peak partial teeth with a radius equal to the gear pitch radius of the radially outwardly extending peak partial teeth. Conversely, the lower half has an integrated roller section between each of the valley half teeth with a radius also equal to the gear pitch radius of the peak partial teeth. The valley partial teeth extend radially inwardly from its roller section. The peak and valley partial teeth are exactly out of phase with each other, as are the roller sections of the upper and lower halves. Essentially, the end roller bearing of the typical gear bearing has been integrated into the normal gear tooth pattern.

Vranish, John M. (Inventor)

2010-01-01

151

BEARS conference UC Berkeley  

Science.gov (United States)

The Berkeley EECS Annual Research Symposium (BEARS) is a conference hosted by UC Berkeley's Electrical Engineering and Computer Sciences department in the College of Engineering. This website provides the agenda for the 2005 BEARS (held on February 10 and 11) along with information on the presenters and abstracts and video footage of their presentations. The conference highlights work from EECS scientists on "advances enabling computing and communications to connect diverse aspects of our world." Topics include: wireless networks, optical communication, the future of the internet, embedded software, machine learning, security, and trust.

152

Optimization of Flapping Airfoils for Maximum Thrust and Propulsive Efficiency  

Directory of Open Access Journals (Sweden)

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. 

I. H. Tuncer

2004-01-01

153

Parametric study of thermal behavior of thrust chamber cooling channels  

Directory of Open Access Journals (Sweden)

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.

Karima E. Amori

2007-01-01

154

Methods for determining atypical gate valve thrust requirements  

International Nuclear Information System (INIS)

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

1995-04-01

155

Study of superconducting magnetic bearing applicable to the flywheel energy storage system that consist of HTS-bulks and superconducting-coils  

International Nuclear Information System (INIS)

The Railway Technical Research Institute conducted a study to develop a superconducting magnetic bearing applicable to the flywheel energy-storage system for railways. In the first step of the study, the thrust rolling bearing was selected for application, and adopted liquid-nitrogen-cooled HTS-bulk as a rotor, and adopted superconducting coil as a stator for the superconducting magnetic bearing. Load capacity of superconducting magnetic bearing was verified up to 10 kN in the static load test. After that, rotation test of that approximately 5 kN thrust load added was performed with maximum rotation of 3000rpm. In the results of bearing rotation test, it was confirmed that position in levitation is able to maintain with stability during the rotation. Heat transfer properties by radiation in vacuum and conductivity by tenuous gas were basically studied by experiment by the reason of confirmation of rotor cooling method. The experimental result demonstrates that the optimal gas pressure is able to obtain without generating windage drag. In the second stage of the development, thrust load capacity of the bearing will be improved aiming at the achievement of the energy capacity of a practical scale. In the static load test of the new superconducting magnetic bearing, stable 20kN-levitation force was obtained.

2010-06-01

156

Hadronic events with low thrust containing isolated leptons  

International Nuclear Information System (INIS)

With the JADE detector at PETRA a search for hadronic events with isolated leptons was performed. At the highest PETRA energies ?s? 46.3 GeV, we found 5 hadronic events with low thrust, T < 0.8, and an isolated muon, where the muon has a large angle ? with respect to the thrust axis, |cos ?|< 0.7. The expectation from standard processes is 1 event at most. The same analysis as for the muons performed for electrons within a restricted angular range, |cos?|< 0.76, did not reveal any event at ?s? 46.3 GeV as compared to an expectation of 0.7

1986-01-01

157

Beryllium satellite thrust cone design, manufacture and test  

International Nuclear Information System (INIS)

Pre-formed beryllium sheet material has been used in the design, manufacturing and test of a satellite thrust cone structure. Adhesive bonding was used for attachment of aluminium flanges and conical segment lap strips. Difficulties in beryllium structure design such as incompatibilities with aluminium and handling problems are discussed. Testing to optimize beryllium-beryllium and beryllium-aluminium adhesive bonds is described. The completed thrust cone assembly has been subjected to static load testing and the results are presented. A summary of the relative merits of the use of beryllium in satellite structures is given with recommendations for future users. (author)

1977-10-07

158

Low-thrust chemical propulsion system pump technology  

Science.gov (United States)

Candidate pump and driver systems for low thrust cargo orbit transfer vehicle engines which deliver large space structures to geosynchronous equatorial orbit and beyond are evaluated. The pumps operate to 68 atmospheres (1000 psi) discharge pressure and flowrates suited to cryogenic engines using either LOX/methane or LOX/hydrogen propellants in thrust ranges from 445 to 8900 N (100 to 2000 lb F). Analysis of the various pumps and drivers indicate that the low specific speed requirement will make high fluid efficiencies difficult to achieve. As such, multiple stages are required. In addition, all pumps require inducer stages. The most attractive main pumps are the multistage centrifugal pumps.

Sabiers, R. L.; Siebenhaar, A.

1981-01-01

159

Hybrid superconductor magnet bearings  

Science.gov (United States)

Hybrid superconductor magnet bearings (HSMB's) utilize high temperature superconductors (HTS's) together with permanent magnets to form a frictionless interface between relatively rotating parts. They are low mass, stable, and do not incur expenditure of energy during normal operation. There is no direct physical contact between rotor and stator, and hence there is no wear and tear. However, just as any other applications of HTS's, it requires a very cold temperature to function. Whereas this might be perceived as a disadvantage on earth, it is of no great concern in space or on the moon. To astronomers, the moon is an excellent site for an observatory, but the cold and dusty vacuum environment on the moon precludes the use of mechanical bearings on the telescope mounts. Furthermore, drive mechanisms with very fine steps, and hence bearings with extremely low friction are needed to track a star from the moon, because the moon rotates very slowly. All aspects considered, the HSMB is about the only candidate that fits in naturally. Here, we present a design for one such bearing, capable of supporting a telescope that weighs about 3 lbs on Earth.

Chu, Wei-Kan

1995-01-01

160

Bear vs Bee  

Science.gov (United States)

This interactive Java applet is a game that challenges a student to solve problems by using logic and rudimentary engineering skills. The goal in each case is to create a conveyance that gets the bear to the pot of honey, avoiding the bees. The game has 32 stages of increasing complexity.

2012-01-01

 
 
 
 
161

Magnetically leviated superconducting bearing  

Energy Technology Data Exchange (ETDEWEB)

A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.

Weinberger, Bernard R. (Avon, CT); Lynds, Jr., Lahmer (Glastonbury, CT)

1993-01-01

162

Rotordynamics of Automotive Turbochargers Linear and Nonlinear Rotordynamics – Bearing Design – Rotor Balancing  

CERN Document Server

This book deals with rotordynamics of automotive turbochargers while encompassing the analysis of the dynamics of rotating machines at very high rotor speeds of 300,000 rpm and above. This interdisciplinary field involves 1. thermodynamics and turbo-matching knowledge to compute working conditions of turbochargers, 2. fluid and bearing dynamics to calculate various operating thrust loads and to design the rotating floating ring bearings (two-oil-film bearings), and 3. tribology to improve the rotor stability and to reduce the bearing friction. Mathematical background in modeling and simulation methods is necessary; however, the prerequisites have been kept to a minimum. The book addresses both practitioners working in the field of rotordynamics of automotive turbochargers and graduate students in mechanical engineering.

Nguyen-Schäfer, Hung

2012-01-01

163

A study on the frictional characteristics of bearing materials for the main coolant pump in SMART  

International Nuclear Information System (INIS)

Experimental frictional and wear characteristics of silicon graphite materials lubricated with high temperature and highly pressurized water to use for the journal bearing and the thrust bearing in the main coolant pump bearing of SMART is studied in this paper. Similar operating condition of the bearings is realized in the tribometer, so the materials are lubricated with high temperature and highly pressurized water. Friction coefficient and wear loss are analyzed to choose the best silicon graphite material. Pin on plate test specimens are used and coned disk springs are used to control the applied force on the specimens. Wear loss and wear width are measured by an precision balance and a micrometer. The friction force is measured by the strain gauge which can be used under high temperature and high pressure. Three kinds of silicon graphite materials are examined and compared with each other, and each material shows similar but different results on frictional and wear characteristics

2001-05-01

164

Naïve Bayesian Classifier for On-line Remaining Useful Life Prediction of Degrading Bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this paper, the estimation of the Residual Useful Life (RUL) of degraded thrust ball bearings is made resorting to a data-driven stochastic approach that relies on an iterative Naïve Bayesian Classifier (NBC) for regression task. NBC is a simple stochastic classifier based on applying Bayes' theorem for posterior estimate updating. Indeed, the implemented iterative procedure allows for updating the RUL estimation based on new information collected by sensors located on the degrading beari...

Di Maio, Francesco; Ng, Selina S. Y.; Tsui, Kwok-leung; Zio, Enrico

2011-01-01

165

Bearing, Gearing, and Lubrication Technology.  

Science.gov (United States)

Results of selected NASA research programs on rolling-element and fluid-film bearings, gears, and elastohydrodynamic lubrication are reported. Advances in rolling-element bearing material technology, which have resulted in a significant improvement in fat...

W. J. Anderson

1978-01-01

166

Particle migration through sealed bearings  

Energy Technology Data Exchange (ETDEWEB)

Tests were performed to determine the ability of various types of shielded bearings to isolate particulate from a clean environment in support of the Direct Optical Initiation (DOI) program. In the DOI firing system, a stronglink mechanism will share the same environment with a high-powered laser which needs uncontaminated optics to perform properly. Two commercially available shielded and sealed bearings were tested along with a sealed bearing designed at Allied Signal Inc., Kansas City Division (KCD). The KCD-designed bearing proved to be the best barrier, but the torque required to function the bearing was magnitudes above the commercial bearings. The commercial sealed bearing was an effective barrier, allowing a small fraction of particles to migrate through, and had a relatively low running torque. The shielded bearing was not acceptable as a particle barrier.

Sundvold, P.D.

1993-08-01

167

Vygotsky and the Three Bears  

Science.gov (United States)

Peggy Kulczewski, a kindergarten classroom teacher, remembers the day when students enjoyed a story she told them from the book "The Three Bears". The students' discussion about comparison of the bears was very helpful to the whole group.

Kulczewski, Peggy

2004-01-01

168

Reactor thrust during boost in a high altitude trajectory  

Energy Technology Data Exchange (ETDEWEB)

Reactor startup of a submarine based missile must be accomplished during boost., so that at burnout the reactor maximum wall temperature is at or near the design value. Because cooling air must be supplied during this period, there exists the possibility of obtaining some thrust to augment the booster. To find how much reactor thrust might be available, a representative high altitude boost trajectory was selected. This is shown together with an estimated pressure recovery curve for the inlet. It has been assumed that by some appropriate means the flow rate passed by the inlet exactly matches that demanded by the reactor and nozzle. Hot day conditions are assumed. The missile power plant was the Tory II-C reactor with its design point-optimized nozzle throat area of 750 square inches. Nozzle expansion is complete. The reactor maximum wall temperature was assumed to be constant at design (2500 degrees F) from time zero. Thus the thrust computed at any time is the maximum possible within the reactor design temperature limitation, and provides a guide to a desirable startup time. Available thrust and reactor exit conditions were obtained with the digital codes Dash N and Nomac.

Moyer, J.H.

1962-11-12

169

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

Energy Technology Data Exchange (ETDEWEB)

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.

NONE

1996-02-01

170

Digital field trip to the Central Nevada Thrust Belt  

Energy Technology Data Exchange (ETDEWEB)

Hydrocarbon exploration in the Central Nevada Thrust Belt is still in its infancy. However, this thrust belt contains all the elements necessary for hydrocarbon accumulations: thick, organically-rich shales; reefs, regional unconformities, karst surfaces, porous sandstones, and extensive and pervasive fractures; anticlines tens of miles long by miles wide; thrust faults that juxtapose potential source and reservoir rocks; and oil seeps. Along a fairway from Las Vegas to Elko, for example, thick Mississippian shales contain 4-6% total organic carbon and are oil-prone and thermally mature. This presentation from a laptop computer and LCD projector is a multimedia version of our October 12-14, 1995 field trip to document the hydrocarbon potential of the thrust belt in Clark, Lincoln, and Nye Counties. Outcrop images were recorded by a digital camera that has a resolution equivalent to a 14 inch computer screen; these images were then downloaded to the computer. All of the images were processed digitally on location to enhance picture quality and color contrast. Many were annotated on location with our observations, measurements, and interpretations. These field annotations are supplemented in this presentation by laboratory analyses. The presentation includes full-color, annotated outcrop images, sounds, and animations. The results show the viability of the new, inexpensive digital cameras to geologic field work in which a multimedia report, ready for presentation to management, can be generated in the field.

Chamberlain, A.K. [Cedar Strat Corp., Hiko, NV (United States); Hook, S.C. [Texaco E& P Technology Department, Houston, TX (United States); Frost, K.R. [Texaco Exploration and Production, Inc., Houston, TX (United States)

1996-12-31

171

Digital field trip to the Central Nevada Thrust Belt  

Energy Technology Data Exchange (ETDEWEB)

Hydrocarbon exploration in the Central Nevada Thrust Belt is still in its infancy. However, this thrust belt contains all the elements necessary for hydrocarbon accumulations: thick, organically-rich shales; reefs, regional unconformities, karst surfaces, porous sandstones, and extensive and pervasive fractures; anticlines tens of miles long by miles wide; thrust faults that juxtapose potential source and reservoir rocks; and oil seeps. Along a fairway from Las Vegas to Elko, for example, thick Mississippian shales contain 4-6% total organic carbon and are oil-prone and thermally mature. This presentation from a laptop computer and LCD projector is a multimedia version of our October 12-14, 1995 field trip to document the hydrocarbon potential of the thrust belt in Clark, Lincoln, and Nye Counties. Outcrop images were recorded by a digital camera that has a resolution equivalent to a 14 inch computer screen; these images were then downloaded to the computer. All of the images were processed digitally on location to enhance picture quality and color contrast. Many were annotated on location with our observations, measurements, and interpretations. These field annotations are supplemented in this presentation by laboratory analyses. The presentation includes full-color, annotated outcrop images, sounds, and animations. The results show the viability of the new, inexpensive digital cameras to geologic field work in which a multimedia report, ready for presentation to management, can be generated in the field.

Chamberlain, A.K. (Cedar Strat Corp., Hiko, NV (United States)); Hook, S.C. (Texaco E P Technology Department, Houston, TX (United States)); Frost, K.R. (Texaco Exploration and Production, Inc., Houston, TX (United States))

1996-01-01

172

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

International Nuclear Information System (INIS)

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)

2005-01-01

173

Seismic activity along the main boundary thrust (MBT), Pakistan  

International Nuclear Information System (INIS)

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 ill 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 cpicenters, 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)

2005-01-01

174

Low thrust hadron events with isolated ? or e from Petra  

International Nuclear Information System (INIS)

In search for new quark flavors, an excess of low thrust events containing muons is found for PETRA energies greater than 46.3 GeV. The muons in these events are quite isolated from hadronic energy as would be expected from pair production of massive quarks. Combining data from all 4 PETRA experiments, there are 14 events with thrust less than 0.8 and the cosine of the angle between the muons direction and the thrust axis less than 0.7. Based directly on measurements taken at lower energy, the expected number of evens is quite accurately predicted to be 2.4. The probability of a statistical fluctuation of this size or larger occurring in a given event selection is 3 x 10/sup -7/. Although these events are consistent with the production of a new quark flavor, the evidence is as yet insufficient to prove that this is the source. No excess of events is seen in the selection of low thrust events with isolated electrons where the sensitivity is substantially lower

1987-01-01

175

Investigations of Thrust Vector Control for High-Alpha Pitchover.  

Science.gov (United States)

Historically, thrust vector control (TVC) system investigations at the Naval Weapons Center have touched on a wide variety of technologies. Emphasis in this paper is on two technologies, the movable-nozzle and the jet-vane TVC, whose performance capabilit...

A. O. Danielson R. B. Dillinger

1989-01-01

176

Centrifugally decoupling touchdown bearings  

Energy Technology Data Exchange (ETDEWEB)

Centrifugally decoupling mechanical bearing systems provide thin tensioned metallic ribbons contained in a support structure. This assembly rotates around a stationary shaft being centered at low speeds by the action of the metal ribbons. Tension springs are connected on one end to the ribbons and on the other end to the support structure. The ribbons pass through slots in the inner ring of the support structure. The spring preloading thus insures contact (or near-contact) between the ribbons and the shaft at rotation speeds below the transition speed. Above this speed, however, the centrifugal force on the ribbons produces a tensile force on them that exceeds the spring tensile force so that the ribbons curve outward, effectively decoupling them from mechanical contact with the shaft. They still remain, however, in position to act as a touchdown bearing in case of abnormally high transverse accelerations.

Post, Richard F

2014-06-24

177

Magnetic bearing and motor  

Science.gov (United States)

A magnetic bearing assembly (10) has an intermediate rotatable section (33) having an outer cylindrical member (30) coaxially suspended by a torsion wire (72) around an axially polarized cylindrical magnet (32). Axial alignment between the pole faces (40-43) of the intermediate section (33) and end surfaces (50-53) of opposed end bells (20, 22) provides a path of least reluctance across intervening air gaps (60-63) for the magnetic flux emanating from magnet (32). Radial dislocation increases the reluctance and creates a radial restoring force. Substitution of radially polarized magnets 107 fixed to a magnetically permeable cylinder (32') and insertion of pairs of armature coil windings (109-112) between the cylinder pair (33') provides an integral magnetic bearing and torsion motor (100) able to provide arcuately limited rotational drive.

Studer, Philip A. (Inventor)

1983-01-01

178

Thrust Area Report, Engineering Research, Development and Technology  

Energy Technology Data Exchange (ETDEWEB)

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.

Langland, R. T.

1997-02-01

179

Active magnetic bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Magnetism is a class of physical phenomena that includes forces exerted by magnets on other magnets. It has its origin in electric currents and the fundamental magnetic moments of elementary particles. A bearing is a machine element that constrains relative motion between moving parts to only the desired motion. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/33682

Khalizeva, A. G.

2013-01-01

180

Interseismic Strain Accumulation Across Metropolitan Los Angeles: Puente Hills Thrust  

Science.gov (United States)

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

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

2012-12-01

 
 
 
 
181

Dialogue for Kids Wild About Bears Sleepy Bear Lesson Plan  

Science.gov (United States)

Each winter, bears hunker down, slow their metabolisms, and pretty much wait out the winter in the safety of some sort of den. This lesson plan, from Idaho Public Television, is a fun way to illustrate to children (probably elementary grades primarily) the process of hibernation. At this site, educators are given the complete lesson plan instructions as well as several links to all sorts of great resources, including links to information on: Bear Diet, Home Range, Reproduction, Bear Research, People and Bears, more Classroom Activities, and more. And, the great addition to the site is a link to a 30-minute video about bears. While the site is somewhat focused on Idaho-specific bear information, teachers should be able to easily integrate the lesson no matter where you are.

182

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

Energy Technology Data Exchange (ETDEWEB)

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.

1994-05-01

183

Optimization of Low-Thrust Spiral Trajectories by Collocation  

Science.gov (United States)

As NASA examines potential missions in the post space shuttle era, there has been a renewed interest in low-thrust electric propulsion for both crewed and uncrewed missions. While much progress has been made in the field of software for the optimization of low-thrust trajectories, many of the tools utilize higher-fidelity methods which, while excellent, result in extremely high run-times and poor convergence when dealing with planetocentric spiraling trajectories deep within a gravity well. Conversely, faster tools like SEPSPOT provide a reasonable solution but typically fail to account for other forces such as third-body gravitation, aerodynamic drag, solar radiation pressure. SEPSPOT is further constrained by its solution method, which may require a very good guess to yield a converged optimal solution. Here the authors have developed an approach using collocation intended to provide solution times comparable to those given by SEPSPOT while allowing for greater robustness and extensible force models.

Falck, Robert D.; Dankanich, John W.

2012-01-01

184

Gravity as Archimedes' thrust and a bifurcation in that theory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Euler's interpretation of Newton's gravity (NG) as Archimedes' thrust in a fluid ether is presented in some detail. Then a semi-heuristic mechanism for gravity, close to Euler's, is recalled and compared with the latter. None of these two "gravitational ethers" can obey classical mechanics. This is logical since the ether defines the very reference frame, in which mechanics is defined. This concept is used to build a scalar theory of gravity: NG corresponds to an incompressi...

Arminjon, Mayeul

2004-01-01

185

Low-thrust chemical propulsion system pump technology  

Science.gov (United States)

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.

Meadville, J. W.

1980-01-01

186

The Prevalence of Tongue Thrusting in Patients with Periodontal Disease  

Directory of Open Access Journals (Sweden)

Full Text Available Statement of Problem: Tongue thrust and/or its consequent swallowing pattern are amongst the parafunctional habits that have always been considered as etiological factors for dental disorders by different investigators.Purpose: The aim of this study was to investigate the prevalence of tongue thrusting and the incidence of periodontal disorders associated with this habit among patients referred to the Department of Periodontology, School of Dentistry, Tehran University of Medical Sciences.Material and Methods: Two hundred and eighty patients, undergoing first phase of periodontal therapy, were selected. Among them, those who had tongue thrusting were diagnosed and periodontal indices (probing depth, gingival recession, spacing and gingival enlargement were measured. Also, crown-root ratio was assessed for each anterior tooth.Results: Tongue thrusting was seen in 27.3%of patients, whereas 29.8% and 33.8% of them showed an increase in periodontal pocket depths in their upper and lower jaws,respectively. Gingival recession was found in the upper jaw in 12.98% and in the lowerjaw in 49.35% of the cases. Crown to root length ratio in 24.6% of the upper incisors and 35.1% of the lower incisors were found to be higher than normal. Spacing was observed between the incisors in 31.2% and 41.6% of the patients in the upper and lower jaws, respectively. Finally 31.2% of the patients showed gingival enlargement.Conclusion: The results of the present study revealed a considerable increase in the prevalence of various periodontal diseases among these subjects. To minimize the clinical problems of such patients, prevention of periodontal diseases through excellent oral hygiene and regular dental visits are suggested.

S.A. Miremadi

2005-06-01

187

A method for increasing thrust reverser utilization on STOL aircraft.  

Science.gov (United States)

A technique for increasing the utilization of thrust reversers on STOL aircraft is described. The technique involves asymmetric orientation of the reversed exhaust in such a manner as to avoid the problems of self-ingestion, even in the presence of a cross wind, and cross ingestion between adjacent engines. Experimental results of ingestion in a single nacelle inlet are discussed and flow visualization pictures are presented. An analytical model of ingestion is described and sample results are shown.

Tatom, J. W.; Dunlap, J. H.; Ledwith, W. A.

1972-01-01

188

Performance of 75-millimeter-bore bearings using electron-beam-welded hollow balls with a diameter ratio of 1.26  

Science.gov (United States)

An experimental investigation was performed to determine the rolling element fatigue life of electron beam-welded hollow balls with a diameter ratio (o.d./i.d.) of 1.26 and to determine the operating characteristics of bearings using these hollow balls. Similar bearings with solid balls were also tested and the data compared. The bearings were operated at shaft speeds up to 28,000 rpm with a thrust load of 2200 N (500 lb). Ball failures during the bearing tests were due to flexure fatigue. The solid and hollow ball bearings tested showed little difference in outer race temperatures and indicated the same bearing torque. The 17.5-mm (0.6875-in.) diameter balls were also tested in the five-ball fatigue tester and showed no significant difference in life when compared with the life of a solid ball.

Coe, H. H.; Parker, R. J.; Scibbe, H. W.

1975-01-01

189

Static tests of a large scale swivel nozzle thrust deflector  

Science.gov (United States)

Tests were conducted on a swivel nozzle thrust deflector installed on a 91 centimeter (36 inch) low pressure ratio tip turbine fan. Fan power was supplied by a J-85 hot gas generator. The configuration was typical of a vertical/short takeoff and landing (V/STOL) aircraft propulsion system employing lift cruise fans. The performance was compared to results obtained on an 0.15 scale cold flow model. Data were obtained at fan pressure ratios from 1.1 to 1.2 and at nozzle deflections from cruise (0 deg) to VTOL (90 deg). The nozzle thrust performance was in good agreement with small scale VTOL thrust coefficients. Configurations with increased nozzle area showed lower performance. Fan operation was routine and nozzle rotation caused no circumferential distortions of the fan exit flow. Nozzle flow characteristics did not repeat small scale model results. Measured flow coefficients were smaller on the large scale test. It was concluded that lack of simulation of pressure and temperature profiles of the tip driven fan was the most probable cause of the discrepancy.

Federspiel, J. F.

1978-01-01

190

Camera Layout Design for the Upper Stage Thrust Cone  

Science.gov (United States)

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.

Wooten, Tevin; Fowler, Bart

2010-01-01

191

Superconducting bearings in flywheels  

International Nuclear Information System (INIS)

Investigations are being carried out into the use of superconducting magnetic bearings to levitate energy storage flywheels. In a planned program of work, Cambridge University are aiming to produce a practical bearing system for Pirouette(TM). The Pirouette(TM) system is designed to provide 5 kWh of recoverable energy which is currently recoverable at a rate of 5 kW (future revisions will provide up to 50 kW). IES (a British Nuclear Fuels subsidiary) the owners of the Pirouette(TM) machine have supplied Cambridge with a flywheel. This flywheel weighs >40 kg and is being levitated using an Evershed-type arrangement in which the superconductor is being used to stabilize the interaction between two magnets. To date we have demonstrated stable levitation in static and low speed tests in a rig designed for low speeds of rotation in air. A second rig which is currently under construction at BNFL will run in vacuum at speeds of up to 50 (orig.)

1998-05-01

192

Nanoprecipitation in bearing steels  

Energy Technology Data Exchange (ETDEWEB)

{theta}-phase is the main hardening species in bearing steels and appears in both martensitically and bainitically hardened microstructures. This work presents a survey of the microstrucural features accompanying nanoprecipitation in bearing steels. Nanoprecipitate structures formed in 1C-1.5Cr wt.% with additions of Cr, Mn, Mo, Si and Ni are studied. The work is combined with thermodynamic calculations and neural networks to predict the expected matrix composition, and whether this will transform martensitically or bainitically. Martensite tetragonality, composition and the amount of retained austenite are related to hardness and the type of nanoprecipitate structures in martensitic grades. The {theta}-phase volume fraction, the duration of the bainite to austenite transformation and the amount of retained austenite are related to hardness and a detailed quantitative description of the precipitate nanostructures. Such description includes compositional studies using energy-dispersive spectroscopy, which shows that nanoprecipitate formation takes place under paraequilibrium. Special attention is devoted to a novel two-step bainite tempering process which shows maximum hardness; we prove that this is the most effective process for incorporating solute into the precipitates, which are finer than those resulting from one-step banitic transformation processes.

Barrow, A.T.W. [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom); Rivera-Diaz-del-Castillo, P.E.J., E-mail: pejr2@cam.ac.uk [SKF University Technology Centre, Department of Materials Science and Metallurgy, University of Cambridge, Cambridge CB2 3QZ (United Kingdom)

2011-11-15

193

Testing of Bearing Materials for Large Two-stroke Marine Diesel Engines  

DEFF Research Database (Denmark)

In large two-stroke marine diesel engines bearings are designed with the intention that these need not be replaced during the life of the engine. The design has shown very good service experiences. The design parameters of the main bearings are, among others, based on the average maximum specific load which the bearing should operate under. In general, the frictional loss is less than 1% of the nominal power of the engine but is still a target for optimization. Fatigue mechanisms of bearing lining material are not fully understood and the design limits with regards to minimum oil film thickness, max oil film pressure and oil film pressure gradient is not established. Large two-stroke journal bearings are not suitable for fatigue test due to the size, the low rotational speed and the complexity of such test-rig. The Disc Fatigue Test Rig (DFTR) was designed with the purpose to test white metal coatings under realistic bearing conditions, in a confined time-frame. The test-rig simulates a scale model of a thrust bearing, in contrary to standard design the bearing lining material is applied to the rotating collar. On each side of the disc three stationary tilting-pads applies a load to the test disc, with a rotational speed of 2000 rpm. Parameters, such as bearing load, rotational speed, oil temperature, oil contamination is controlled/monitored in order to achieve repeatability and a systematic approach to the experiments. Test performed on the test-rig shows good correlation on the fatigue cracks with those experienced on large two-stroke journal bearings.

Klit, Peder

2013-01-01

194

Electro-Hydrodynamic (EHD) Thrust Analysis in Wire-Cylinder Electrode Arrangement  

Science.gov (United States)

The thrust generation by electro-hydrodynamic (EHD) effect has been studied for a wire-cylinder arrangement under high DC voltage. Series of measurements have been conducted in order to determine the relationship between generated thrust and corona discharge current, as well as its dependence on geometrical characteristics of the electrodes, e.g. electrode gap, wire and cylinder radii. The experimental investigation has shown a linear relationship between the generated thrust and the discharge current, while parametric analysis showed that increased electrode gap and emitter radius reduces the thrust. On the other hand, large gaps favor the thrust per unit power ratio.

Konstantinos, N. Kiousis; Antonios, X. Moronis; Wolf, G. Fruh

2014-04-01

195

Direct thrust measurement of a permanent magnet helicon double layer thruster  

International Nuclear Information System (INIS)

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

2011-04-04

196

Selected conveyor idler roller bearings  

Energy Technology Data Exchange (ETDEWEB)

It is argued that rating life of rolling bearings is not a useful basis for determining conveyor idler roller life because it assumes relatively clean and well lubricated operation, which is often not what happens. The bearing life calculation procedure is outlined and effects of misalignment and maintenance are discussed. Results of research on the effects of dry contaminants are outlined, and the advantage of antiseizure bearings and the importance of the seals are presented.

1986-07-01

197

Grease lubrication in rolling bearings  

CERN Document Server

The definitive book on the science of grease lubrication for roller and needle bearings in industrial and vehicle engineering. Grease Lubrication in Rolling Bearings provides an overview of the existing knowledge on the various aspects of grease lubrication (including lubrication systems) and the state of the art models that exist today. The book reviews the physical and chemical aspects of grease lubrication, primarily directed towards lubrication of rolling bearings. The first part of the book covers grease composition, properties and rheology, including thermal

Lugt, Piet M

2012-01-01

198

YBCO texturation and applications of superconducting magnetic bearings in flywheels for energy storage  

International Nuclear Information System (INIS)

A thrust bearing has been built consisting of 6 melt-textured YBCO pellets (diameter 30 x 18 mm) and a Nd-Fe-B ring magnet. The maximum levitation force of the bearing was 65 N at zero gap. Vertical stiffness at 1 mm gap was 440 N/cm, lateral stiffness was 130 N/cm. The bearing has been integrated into a flywheel system rotating a 2.8 kg disk at speeds up to 15 000 rpm. The maximum energy capacity was 4.8 Wh. It can be expected that further refinement of this technology should allow the operation of superconducting flywheels in the kWh range. (orig.)

1993-01-01

199

A Comparison Study of Magnetic Bearing Controllers for a Fully Suspended Dynamic Spin Rig  

Science.gov (United States)

NASA Glenn Research Center (GRC) has developed a fully suspended magnetic bearing system for the Dynamic Spin Rig (DSR) that is used to perform vibration tests of turbomachinery blades and components under spinning conditions in a vacuum. Two heteropolar radial magnetic bearings and a thrust bearing and the associated control system were integrated into the DSR to provide noncontact magnetic suspension and mechanical excitation of the 35 lb vertical rotor with blades to induce turbomachinery blade vibration. A simple proportional-integral-derivative (PID) controller with a special feature for multidirectional radial excitation worked very well to both support and shake the shaft with blades. However, more advanced controllers were developed and successfully tested to determine the optimal controller in terms of sensor and processing noise reduction, smaller rotor orbits, and energy savings for the system. The test results of a variety of controllers we demonstrated up to the rig's maximum allowable speed of 10,000 rpm are shown.

Choi, Benjamin; Johnson, Dexter; Morrison, Carlos; Mehmed, Oral; Huff, Dennis (Technical Monitor)

2002-01-01

200

EVALUATION OF A LOW FRICTION - HIGH EFFICIENCY ROLLER BEARING ENGINE  

Energy Technology Data Exchange (ETDEWEB)

This Low Friction (High Efficiency Roller Bearing) Engine (LFE) report presents the work done by The Timken Company to conduct a technology demonstration of the benefits of replacing hydrodynamic bearings with roller bearings in the crankshaft and camshaft assemblies of an internal combustion engine for the purpose of collecting data sufficient to prove merit. The engines in the present study have been more extensively converted to roller bearings than any previous studies (40 needle roller bearings per engine) to gain understanding of the full potential of application of bearing technology. The project plan called for comparative testing of a production vehicle which was already respected for having demonstrated low engine friction levels with a rollerized version of that engine. Testing was to include industry standard tests for friction, emissions and fuel efficiency conducted on instrumented dynamometers. Additional tests for fuel efficiency, cold start resistance and other measures of performance were to be made in the actual vehicle. Comparative measurements of noise, vibration and harshness (NVH), were planned, although any work to mitigate the suspected higher NVH level in the rollerized engine was beyond the scope of this project. Timken selected the Toyota Avalon with a 3.5L V-6 engine as the test vehicle. In an attempt to minimize cost and fabrication time, a ‘made-from’ approach was proposed in which as many parts as possible would be used or modified from production parts to create the rollerized engine. Timken commissioned its test partner, FEV Engine Technology, to do a feasibility study in which they confirmed that using such an approach was possible to meet the required dimensional restrictions and tolerances. In designing the roller bearing systems for the crank and cam trains, Timken utilized as many production engine parts as possible. The crankshafts were produced from production line forgings, which use Timken steel, modified with special machining and heat treatment. Timken designed and manufactured all of the roller bearing related components such as the thrust bearing package. The production connecting rods and camshafts could not be used for the roller bearing engine, so new ones were produced according to the team’s designs using Timken steel. The remaining miscellaneous components were designed and procured by FEV. Timken prepared a display version of the crankshaft portion of the production engine without connecting rods which could be driven by a motor through a cogged-belt and electrically actuated clutch arrangement. A modified version was also made in which the engine was outfitted with roller bearings on the main bearing positions. Preliminary tests showed that the rollerized engine was running with 1/3 less friction than the standard display engine. Additional friction testing and noise characterization was cut short because of shipping damage to the rollerized engine display and because of other project priorities. The team did successfully demonstrate the ability to package roller bearings satisfactorily in numerous locations in a typical automotive engine. The scope of this project did not include durability demonstration and that subject would have to be addressed in any follow-on work. In the actual test phase, the rollerized engine did show significantly less friction in motored dynamometer tests compared to its production equivalent. The 5-10% improvement measured in this study was about half that seen in other studies. However, the fired test results did not show a reduction in friction which did not match prior experience or expectations. Subsequent teardown and inspection of the rollerized engine revealed potential sources of excessive friction in the experimental application. These features would be eliminated in a design not based on modification of production parts. The team is confident (based on experience) that friction reduction would be realized with proper modifications.

Kolarik, Robert V. II; Shattuck, Charles W.; Copper, Anthony P.

2009-06-30

 
 
 
 
201

Thermal barrier coatings (TBC's) for high heat flux thrust chambers  

Science.gov (United States)

The last 30 years materials engineers have been under continual pressure to develop materials with a greater temperature potential or to produce configurations that can be effectively cooled or otherwise protected at elevated temperature conditions. Turbines and thrust chambers produce some of the harshest service conditions for materials which lead to the challenges engineers face in order to increase the efficiencies of current technologies due to the energy crisis that the world is facing. The key tasks for the future of gas turbines are to increase overall efficiencies to meet energy demands of a growing world population and reduce the harmful emissions to protect the environment. Airfoils or blades tend to be the limiting factor when it comes to the performance of the turbine because of their complex design making them difficult to cool as well as limitations of their thermal properties. Key tasks for space transportation it to lower costs while increasing operational efficiency and reliability of our space launchers. The important factor to take into consideration is the rocket nozzle design. The design of the rocket nozzle or thrust chamber has to take into account many constraints including external loads, heat transfer, transients, and the fluid dynamics of expanded hot gases. Turbine engines can have increased efficiencies if the inlet temperature for combustion is higher, increased compressor capacity and lighter weight materials. In order to push for higher temperatures, engineers need to come up with a way to compensate for increased temperatures because material systems that are being used are either at or near their useful properties limit. Before thermal barrier coatings were applied to hot-section components, material alloy systems were able to withstand the service conditions necessary. But, with the increased demand for performance, higher temperatures and pressures have become too much for those alloy systems. Controlled chemistry of hot-section components has become critical, but at the same time the service conditions have put our best alloy systems to their limits. As a result, implementation of cooling holes and thermal barrier coatings are new advances in hot-section technologies now looked at for modifications to reach higher temperature applications. Current thermal barrier coatings used in today's turbine applications is known as 8%yttria-stabilized zirconia (YSZ) and there are no coatings for current thrust chambers. Current research is looking at the applicability of 8%yttria-stabilized hafnia (YSH) for turbine applications and the implementation of 8%YSZ onto thrust chambers. This study intends to determine if the use of thermal barrier coatings are applicable for high heat flux thrust chambers using industrial YSZ will be advantageous for improvements in efficiency, thrust and longer service life by allowing the thrust chambers to be used more than once.

Bradley, Christopher M.

202

Superconducting bearings for flywheel applications  

DEFF Research Database (Denmark)

A literature study on the application of superconducting bearings in energy storage flywheel systems. The physics of magnetic levitation and superconductors are presented in the first part of the report, followed by a discussion of the literature found onthe applications of superconducting bearings in flywheels.

Abrahamsen, A.B.

2001-01-01

203

Radial Clearance of Antifriction Bearings.  

Science.gov (United States)

The article concerns in detail the radial clearance of different antifriction bearings which belong to important parameters which influence the longevity of the bearing to a certain extent. The effect of the influence of assembly and the wear on the radia...

V. Patocka

1968-01-01

204

The Migration of Polar Bears.  

Science.gov (United States)

As the polar bear roams widely over its Arctic habitat in quest of its principal food--seal meat, little is known about him. Now a technique is at hand that promises to fill some of the gaps in our knowledge of the polar bear's life. The technique involve...

V. Flyger M. R. Townsend

1968-01-01

205

Finite strain and strain variation analysis in the Sheeprock Thrust Sheet: an internal thrust sheet in the Provo salient of the Sevier Fold-and-Thrust belt, Central Utah  

Science.gov (United States)

The Sheeprock thrust sheet in west-central Utah is an internal thrust sheet in the Provo salient of the Sevier fold-and-thrust belt. We have measured finite strain in quartzites (the dominant lithology), sampled along a square grid within the thrust sheet, using the modified normalized Fry method (McNaught M.A. (1994) Modifying the normalized Fry method for aggregates of non-elliptical grains. Journal of Structural Geology16 493-503). The {X}/{Y} and {X}/{Z} axial ratios from unsampled locations within the sample area were estimated using the spatial statistics approach. The strain ellipsoids exhibit a variable three-dimensional orientation pattern resulting from modification of the initial layer parallel shortening (LPS) strain ellipsoid by fault parallel shear in conjunction with vertical flattening and/or horizontal stretching indicating that the thrust sheet did not undergo plane strain deformation in the transport plane. This suggests that the plane strain assumption used in drawing restorable balanced cross-sections breaks down for internal thrust sheets with more than one penetrative-strain producing deformation event. The {X}/{Z} strain axial ratios decrease away from the thrust towards the middle of the sheet. The {X}/{Y} strain axial ratios from interpolated image diagrams indicate transport-parallel stretching at the front end of the sheet and strike-parallel stretching at the back end of the sheet. The footwall and hanging wall finite strain patterns are similar indicating that most of the strain in the Sheeprock thrust sheet developed early in the deformation history of the thrust sheet before and perhaps during the growth of a large fault propagation fold pair.

Mukul, Malay; Mitra, Gautam

1998-04-01

206

Flywheel Challenge: HTS Magnetic Bearing  

International Nuclear Information System (INIS)

A 200 mm cylindrical engineering prototype high temperature superconducting (HTS) was designed and fabricated. Measurements show that the 17 kg PM rotor can suspend safely 1000 kg in axial direction and 470 kg radially. The rationale for the bearing performance is to stabilize a 400 kg rotor of a new compact 5 kWh/280 kW flywheel energy storage system (COM - FESS). Measurements of the magnetic bearing force, stiffness and drag-torque are presented indicated the successful targeting a milestone in the HTS bearing technology. The influence of the PM configuration and the YBCO temperature on the bearing performance was experimentally studied, providing high-force or high-stiffness behaviour. The axial stiffness 5 kN/mm at 0.5 mm displacement is the highest value of a HTS bearing we know

2006-06-01

207

Nonlinear control of magnetic bearings  

Science.gov (United States)

In this paper we present a variety of nonlinear controllers for the magnetic bearing that ensure both stability and robustness. We utilize techniques of discontinuous control to design novel control laws for the magnetic bearing. We present in particular sliding mode controllers, time optimal controllers, winding algorithm based controllers, nested switching controllers, fractional controllers, and synchronous switching controllers for the magnetic bearing. We show existence of solutions to systems governed by discontinuous control laws, and prove stability and robustness of the chosen control laws in a rigorous setting. We design sliding mode observers for the magnetic bearing and prove the convergence of the state estimates to their true values. We present simulation results of the performance of the magnetic bearing subject to the aforementioned control laws, and conclude with comments on design.

Pradeep, A. K.; Gurumoorthy, R.

1994-01-01

208

Large-scale geometry of Montana thrust belt  

Energy Technology Data Exchange (ETDEWEB)

Regional plunge of a structural culmination in the Sawtooth Mountains, combined with seismic profiles and borehole data, show that the imbricated faults of the Montana Disturbed belt gather upward to merge into a duplex beneath a large thrust plate dominated by the Precambrian Belt Supergroup. The duplex formed after deposition of the Paleocene St. Mary River Formation. This thrust plate overlies the Lewis, Hoadley, El dorado, Steinbach, and related thrust faults and forms the main ranges of the Montana Rocky Mountains. The plate is shaped like a northeasterly tapering wedge; it is 3 to 4 km (10,000 to 13,000 ft) thick at its leading edge, but thickens to more than 25 km (15 mi) to the southwest. At its leading edge, the plate carries lower parts of the Belt supergroup, including the Greyson, Empire, and Spokane formations. These units and overlying parts of the Belt Supergroup thicken dramatically westward within the plate, and the older, very thick, metamorphosed Prichard Formation emerges along the Purcell and related anticlinoria. The plate forms a south-facing monocline along the Lewis and Clark line. The monocline is corrugated into a series of southeast-plunging en echelon folds of Late Cretaceous age and merges with the southern terminus of the Purcell anticlinorium. Along these folds, metamorphosed Belt strata of the plate plunge systematically beneath Paleozoic and Mesozoic rocks that are preserved in a regional structural depression at the foot of the monocline. Geometric constructions based on areal geology suggest that the monocline has 25 km (15 mi) of structural relief and overlies a major footwall ramp that continues northward beneath the Purcell anticlinorium. This footwall ramp corresponds to the depositional locus for the easterly tapering belt strata of the plate, suggesting a total northeasterly displacement of about 50 km (30 mi) for the plate.

Sears, J.W.; Dolberg, D.M.

1986-08-01

209

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

Energy Technology Data Exchange (ETDEWEB)

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

Dillon, J.T. (Alaska Div. of Geological and Geophysical Surveys, Fairbanks (USA)); Haxel, G.B. (Geological Survey, Flagstaff, AZ (USA)); Tosdal, R.M. (Geological Survey, Menlo Park, CA (USA))

1990-11-10

210

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

Science.gov (United States)

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

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

2009-12-01

211

Design of high power electromechanical actuator for thrust vector control  

Science.gov (United States)

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.

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

1991-01-01

212

Pulsatory phenomenon in a thrust optimized contour nozzle  

Energy Technology Data Exchange (ETDEWEB)

A numerical study of the flow in an axisymmetric over-expanded thrust optimized contour nozzle is presented. The separation flow structures at different pressure ratios are investigated. The start-up process exhibits two different shock structures. For a range of pressure ratios, hysteresis phenomenon occurs between these two separation patterns. For a larger pressure ratio, where the principal separation point is always inside the nozzle, another phenomenon appears. This phenomenon results in an oscillatory longitudinal quasi periodic movement of the separation structure. The computed nozzle wall pressures show a correct agreement with the experimental measurements and the pulsations frequency of the oscillatory phenomenon is also well predicted. (authors)

Nebbache, A.; Pilinski, C. [Institut National de Recherches Agronomiques (INRA), CORIA-LMFN, UMR 6614, 76 - Rouen (France)

2006-05-15

213

Passive Thrust Oscillation Mitigation for the CEV Crew Pallet System  

Science.gov (United States)

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.

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

2012-01-01

214

Trajectory control with continuous thrust applied to a rendezvous maneuver  

Science.gov (United States)

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.

Santos, W. G.; Rocco, E. M.

2013-10-01

215

Lubrication of 35-millimeter-bore ball bearings of several designs at speeds to 2.5 million DN  

Science.gov (United States)

Parametric tests were conducted with 35mm bore, angular contact ball bearings with either a single or double-outer-land-guided cage. The bearings were either lubricated by oil jets or employed inner ring lubrication. Outer ring cooling was added in selected tests. Test conditions were a radial load of 222 N (50 lb) and/or a thrust load of 667 N (150 lb), shaft speeds to 72,000 rpm, and an oil inlet temperature of 394 K (250 F). Lubricant flow to the bearing ranged rom 300 to 1900 cc/min (0.08 to 0.50 gal/min). All bearings were successfully run at speeds to 2.5 million DN. Increasing the lubricant flow decreased bearing ring temperatures but increased bearing power loss. The power loss and race temperatures of a jet lubricated bearing with double-outer-land-guided cage were always higher than those of the single-land-guided-design at similar test conditions. The lowest bearing operating temperatures were achieved when inner ring lubrication and outer ring cooling were combined. Cage slip of a double-outer-land-guided cage was approximately twice that of a single-outer-land-guided cage.

Signer, H. R.; Schuller, F. T.

1982-01-01

216

Bearing development program for a 25 kWe solar-powered organic Rankine-cycle engine  

Science.gov (United States)

The bearing development program is summarized for a 25-kWe power conversion subsystem (PCS) consisting of an organic Rankine-cycle engine, and permanent magnetic alternator (PMA) and rectifier to be used in a 100-kWe point-focusing distributed receiver solar power plant. The engine and alternator were hermetically sealed and used toluene as the working fluid. The turbine, alternator, and feed pump (TAP) were mounted on a single shaft operating at speeds up to 60,000 rev/min. Net thermal-to-electric efficiencies in the range of 21 to 23% were demonstrated at the maximum working fluid temperature of 400 C (750 F). A chronological summary of the bearing development program is presented. The primary causes of bearing wear problems were traced to a combination of rotordynamic instability and electrodynamic discharge across the bearing surfaces caused by recirculating currents from the PMA. These problems were resolved by implementing an externally supplied, flooded-bearing lubrication system and by electrically insulating all bearings from the TAP housing. This program resulted in the successful development of a stable, high-speed, toluene-lubricated five-pad tilting-pad journal bearing and Rayleigh step thrust bearing system capable of operating at all inclinations between horizontal and vertical.

Nesmith, B.

1985-01-01

217

Magnetic Bearing Control Approach Using Flux Feedback.  

Science.gov (United States)

A magnetic bearing control approach using flux feedback is described and test results for a laboratory model magnetic bearing actuator are presented. Test results were obtained using a magnetic bearing test fixture, which is also described. The magnetic b...

N. J. Groom

1989-01-01

218

Alex the Bear Goes to Child Care  

Medline Plus

Full Text Available ... Tools » Meet Alex the Bear Meet Alex the Bear, a new friend of Child Care Aware® Going ... experience for both children and parents. Alex the Bear, the newest friend of Child Care Aware®, seeks ...

219

Adaptive Spindle Balancing Using Magnetically Levitated Bearings.  

Science.gov (United States)

A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings off some important advantages over conventional ball, roller, or journal bearings such as reduced frictional drag, no physical cont...

Barney Lauffer Petteys Redmond Sullivan

1999-01-01

220

Thrust-breakthrough of asymmetric anticlines: Observational constraints from surveys in the Brooks Range, Alaska  

Science.gov (United States)

To gain insights into the processes governing the thrust-truncation of anticlines, we conducted a field study of the thrust-truncated folds in the remote Brooks Range of northern Alaska, where there is a transition in fold style from symmetric detachment folds to thrust-truncated asymmetric folds. In order to document the detailed geometry of the km-scale folds exposed in cliff-forming, largely inaccessible outcrops, a new surveying technique was developed that combines data from a theodolite and laser range finder. The field observations, survey profiles, and cross section reconstructions, indicate that late-stage thrust breakthrough of the anticlines within the mechanically competent Lisburne Group carbonates accommodated continued shortening when other mechanisms became unfeasible, including fold tightening, forelimb rotation, and parasitic folding in the anticline forelimbs. These results provide constraints on the processes that govern the transition from buckle folding to thrust truncation in fold-and-thrust belts worldwide.

Jadamec, Margarete A.; Wallace, Wesley K.

2014-05-01

 
 
 
 
221

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

Energy Technology Data Exchange (ETDEWEB)

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

Lafleur, T.; Charles, C.; Boswell, R. W. [Space Plasma, Power and Propulsion Group, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Takahashi, K. [Space Plasma, Power and Propulsion Group, Research School of Physics and Engineering, The Australian National University, Canberra ACT 0200 (Australia); Department of Electrical Engineering and Computer Science, Iwate University, Morioka 020-8551 (Japan)

2011-08-15

222

Compact and High Thrust Air Turbo Ram Engine  

Science.gov (United States)

The Air Turbo Ramjet (ATR) is a combined cycle engine which performs like a turbojet engine at subsonic speeds and a ramjet at supersonic speeds and therefore the ATR is an attractive propulsion system for the wide operation range (e.g. Mach 0 to Mach 4). The ATR can provide a higher specific impulse than a solid fuel rocket engine and a higher thrust per frontal area than a turbojet engine. The major ATR components are the inlet, fan (compressor), turbine, gas generator, combustor and exhaust nozzle. In the ATR, the turbine drive gas is generated by a decomposed liquid or solid fuel gas generator. In order to carry heavier payloads and to attain shorter flight time, the compact and high thrust engine is required. In this study, the ram combustor with the double-staged flameholders and the fan with tandem blade were introduced to shorten the engine length and to increase the fan pressure ratio, respectively. Furthermore, the engine testing was carried out on sea level static condition to confirm the engine component integration technologies for the ATR propulsion system.

Hasegawa, Hiroaki; Kitahara, Kazuki; Inukai, Yasuo

223

Research at IMU: achievements, thrust areas and future challenges  

Directory of Open Access Journals (Sweden)

Full Text Available There have been significant achievements inresearch at IMU as indicated by the increasing amountof external funds obtained, and number of publicationsand postgraduate students produced since it startedits research activities in the year 2000. However, it isa great challenge indeed to ensure sustainability ofour research, which is currently heavily dependent oninternal funding. There is a need to realign our strategiesto further enhance our competitiveness in securingexternal funding for research. In line with this, theInstitute for Research, Development and Innovation(IRDI was officially established on 18 September2012. The Institute will serve as a platform to supportall research activities at IMU. There are four Centresof Excellence based on the identified thrust areas underIRDI, namely 1 Centre for Bioactive Molecules andDrug Discovery; 2 Centre for Environmental andPopulation Health; 3 Centre for Cancer and StemCell Research, and 4 Centre for Health ProfessionalEducation Research. Major findings based on research inthese four thrust areas are reviewed in this paper. Withthe strategic planning and establishment of IRDI, it isour aspiration to bring research at IMU to a higher level.

Wan-Loy Chu

2013-04-01

224

Design and test of electromechanical actuators for thrust vector control  

Science.gov (United States)

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.

Cowan, J. R.; Weir, Rae Ann

1993-01-01

225

Evaluation of cold isostatic pressing for high pressure thrust chambers  

Energy Technology Data Exchange (ETDEWEB)

The objectives of this program have been to investigate new fabrication methods and design techniques, which potentially reduce fabrication time and cost, and also increase rocket thrust chamber life. For these purposes, the authors have developed the CIP (Cold Isostatic Pressing) forming method based on powder metallurgy. With the CIP forming method, a very complaint closeout is easily obtained while sustaining sufficient bonding strength between the copper liner and the closeout, and providing perfect sealing of coolant channels. A metallurgical test was performed before the fabrication of a trial combustion chamber to determine the forming conditions of the sintered closeout which would fulfill the required design conditions. A trial combustion chamber with an OFHC (Oxygen Free High Conductivity) copper liner was then made for a design combustion pressure of 15 MPa and thrust level of 10kN. The combustion tests of the trial combustion chamber were conducted at chamber pressure of up to 9 MPa for 10 runs to confirm the reliability of the CIP formed chamber.

1985-01-01

226

Design of Force Sensor Leg for a Rocket Thrust Detector  

Science.gov (United States)

A hybrid rocket is composed of a solid fuel and a separate liquid or gaseous oxidizer. These rockets may be throttled like liquid rockets, are safer than solid rockets, and are much less complex than liquid rockets. However, hybrid rockets produce thrust oscillations that are not practical for large scale use. A lab scale hybrid rocket at the University of Arkansas at Little Rock (UALR) Hybrid Rocket Facility is used to develop sensors to measure physical properties of hybrid rockets. Research is currently being conducted to design a six degree of freedom force sensor to measure the thrust and torque in all three spacial dimensions. The detector design uses six force sensor legs. Each leg utilizes strain gauges and a Wheatstone bridge to produce a voltage propotional to the force on the leg. The leg was designed using the CAD software ProEngineer and ProMechanica. Computer models of the strains on the single leg will be presented. A prototype leg was built and was tested in an INSTRON and results will be presented.

Woten, Douglas; McGehee, Tripp; Wright, Anne

2005-03-01

227

Thrust allocation in semi-submersible rig using model predictive control  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A thrust allocation system is used to determine how the desired forces, computed by a high level control sytem, can be distributed among the thrusters. The main goal of the thrust allocation is to obtain the desired force, but other objectives can also be included. Such secondary goals can be to minimize fuel consumption, keep wear and tear of the thruster to a minimum and avoid overloading the power systems. The thrust allocation should also take forbidden sectors and actuator rate constrain...

Johannessen, Irene

2007-01-01

228

Optimization of Low-Thrust Earth-Moon Transfers Using Evolutionary Neurocontrol:  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Although low-thrust propulsion is an interesting option for scientific and reconnaissance missions to targets in planetary space, like the Moon, associated transfer strategies pose challenging requirements in terms of optimal control. The method of Evolutionary Neurocontrol (ENC), which has been applied very successfully to interplanetary low-thrust transfer problems, is now used for solving this type of steering problem. For exemplary validation, two low-thrust transfers from an Earth-bound ...

Ohndorf, A.; Dachwald, B.; Gill, E. K. A.

2009-01-01

229

Three-dimensional architecture of the Nankai accretionary prism's imbricate thrust zone off Cape Muroto, Japan: Prism reconstruction via en echelon thrust propagation  

Science.gov (United States)

A 9 km wide, 92 km long, three-dimensional (3-D) seismic reflection volume acquired off Shikoku Island, Japan, images the seaward portion of the subduction of the Philippine Sea plate at the Nankai Trough and Nankai accretionary prism. Detailed interpretation of the imbricate thrust and protothrust zones, the portions of the prism between the deformation front and the first out-of-sequence thrust, shows a high degree of variability in the thrust faults that all parallel the frontal thrust but are arranged in en echelon patterns along strike and frequently include complications such as piggyback faults and fault splays. Interestingly, the sinuous seafloor morphology of the prism does not accurately reflect the en echelon 3-D architecture of the primary prism thrusts. Seafloor morphology appears to average across several thrusts along strike and is further modified by near-surface thrust splays and backthrusts, suggesting that care must be taken in interpreting seafloor relief in terms of lateral continuity or thrust fault geometry. Subduction of the Kinan seamounts 20 km northeast of the center of the Muroto 3-D volume generated a scallop-shaped embayment in the prism; the rebuilding process appears to influence the northeastern portion of the 3-D volume where a ˜625 m landward step in the position of the frontal thrust and numerous changes in prism architecture are observed. These observations imply that accretionary prisms may reattain equilibrium following seamount subduction by lateral en echelon fault propagation into damaged zones that facilitate an increase accretion rate until a laterally continuous deformation front is reestablished.

Gulick, S. P. S.; Bangs, N. L. B.; Shipley, T. H.; Nakamura, Y.; Moore, G.; Kuramoto, S.

2004-02-01

230

Development of a two-dimensional dual pendulum thrust stand for Hall thrusters  

International Nuclear Information System (INIS)

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

2007-11-01

231

Variation of pitching moment with engine thrust for a twin-engine commercial jet aircraft  

Science.gov (United States)

Flight tests were made to determine the effect of engine net thrust on airplane pitching moment for a twin-engine commercial jet transport in the approach, climbout and descent, and cruise configurations. The results indicate that for all the conditions analyzed, the pitching moment due to thrust is somewhat higher than that estimated from the product of net thrust and its moment arm (perpendicular distance from thrust axis to the airplane center of gravity). The differences are attributed to additional moments produced by nacelle normal force, jet-induced downwash, and interaction between wing flow and engine nacelle flow.

Shanks, R. E.

1977-01-01

232

Structural framework of the Cenozoic QILIAN SHAN-Nan Shan thrust belt, NORTHEASTERN TIBETAN PLATEAU  

Science.gov (United States)

The Qilian Shan- Nan Shan thrust belt defines the northern margin of the Tibetan Plateau and results from Cenozoic India-Asia collision. The thrust belt is constructed in a region that had experienced early Paleozoic collisional tectonics and Jurassic-Cretaceous extension. This complexity has made the evaluating the magnitude of the Cenozoic shortening across the thrust belt difficult. In order to address this issue, we conduct detailed field mapping in a north-south traverse across the Shule Nan Shan in the north and Tuolai Nan Shan in the south in the central Qilian Shan-Nan Shan thrust belt (N38°39'-29' E99°21'-04'). Our work reveals that the Cenozoic thrusts in the study area are dominantly north-dipping. The Shule thrust bounds the southern edge of the Shule Nan Shan and strikes northwest. The fault places primarily Ordovician volcanic rocks and Carboniferous strata over Cenozoic sediments; the latter are largely covered by Quaternary deposits. As the fault does not cut Quaternary sediments, it appears that the Shule thrust is inactive. Cenozoic and Cretaceous redbeds are locally exposed below the Shule thrust in deep-cut valleys. In contrast to the northwest strike, north-dipping thrusts along the south edge and within the Tuolai Nan Shan in the south are dominantly east-striking. These thrusts merge with one another to the east and terminate at the northwest-striking Shule thrust. This relationship may be explained by the development of a crustal-scale duplex system with the Shule thrust as a roof structure. The hanging wall of the Tuolai thrust comprises a high-grade metamorphic complex within which an east-striking right-slip ductile shear zone occurs. A sample from mylonitized granitoid in the shear zone yields a U-Pb zircon age of ~920 Ma. The metamorphic complex is overlain by Permian to Jurassic strata that are complexly folded and together thrust over Neogene strata in the south. A regionally extensive unconformity, which lies between Ordovician-Silurian strata below and Carboniferous-Permian strata and ¬¬is repeated Cenozoic thrusts, is recognized during mapping. This marker together with scattered Mesozoic strata is being used in constructing a balanced cross section across the central Qilian Shan-Nan Shan thrust belt with the aim of establishing the magnitude of Cenozoic shortening.

Reith, R. C.; Yin, A.; Dong, S.; Liu, W.; Zuza, A. V.; Zhang, J.; Wu, C.; Wu, L.; Gong, J.

2012-12-01

233

Thrust Ripples Reduction for a Vector Controlled Permanent Magnet Linear Synchronous Motor with IMC Controller  

Directory of Open Access Journals (Sweden)

Full Text Available The significant drawback of PMLSM is thrust ripples, which is mainly generated by the detent force caused by the interaction of the permanent magnet and iron core without input current in armature winding. It is the function of mover position relative to the stator. This will deteriorate the performance of the drive system in high precision applications. This paper focus on the thrust ripples reduction. To minimize the thrust ripples and realize the high-precision control, the components of thrust ripples are extracted first and then compensate with PI and IMC (Internal Model Control controller

RAMESH BABU.DEVA

2013-06-01

234

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

Directory of Open Access Journals (Sweden)

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.

Maria Blinova

2012-09-01

235

Mixed-mu superconducting bearings  

Energy Technology Data Exchange (ETDEWEB)

A mixed-mu superconducting bearing including a ferrite structure disposed for rotation adjacent a stationary superconductor material structure and a stationary permanent magnet structure. The ferrite structure is levitated by said stationary permanent magnet structure.

Hull, John R. (Hinsdale, IL); Mulcahy, Thomas M. (Western Springs, IL)

1998-01-01

236

High-temperature bearing lubricants  

Science.gov (United States)

Synthetic paraffinic oil lubricates ball bearings at temperatures in the 600 degrees F range. The lubricant contains antiwear and antifoam additives, is thermally stable in the high temperature range, but requires protection from oxygen.

Anderson, W. J.; Parker, R. J.; Zaretsky, E. V.

1968-01-01

237

A Passive Magnetic Bearing Flywheel  

Science.gov (United States)

A 100 percent passive magnetic bearing flywheel rig employing no active control components was designed, constructed, and tested. The suspension clothe rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm, which is 65 percent above the first critical speed of 3336 rpm. Operation was not continued beyond this point because of the excessive noise generated by the air impeller and because of inadequate containment in case of failure. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

Siebert, Mark; Ebihara, Ben; Jansen, Ralph; Fusaro, Robert L.; Morales, Wilfredo; Kascak, Albert; Kenny, Andrew

2002-01-01

238

Roller bearings for drilling aggregates  

Energy Technology Data Exchange (ETDEWEB)

Rotary tables, curculating heads, lifting hooks, hoisting devices, and circulation pumps are aggregates in deep drilling for liquid and gaseous energy sources. These aggregates are often carried in special bearings.

Herles, G.; Stoecklein, W.; Gusovius, E.; Dittmann, R.

1982-01-01

239

Geometry of Thrust Faults Beneath Amenthes Rupes, Mars  

Science.gov (United States)

Amenthes Rupes is a 380 km-long lobate fault scarp located in the eastern hemisphere of Mars near the dichotomy boundary. The scarp is marked by about 1 km of vertical separation across a northeast dipping thrust fault (top to the SW) and offsets heavily-cratered terrain of Late Noachian age, the visible portion of which was in place by 3.92 Ga and the buried portion in place between 4.08 and 4.27 Ga. The timing of scarp formation is difficult to closely constrain. Previous geologic mapping shows that near the northern end of Amenthes Rupes, Hesperian age basalts terminate at the scarp, suggesting that fault slip predated the emplacement of these flows at 3.69 to 3.9 Ga. Maxwell and McGill also suggest the faulting ceased before the final emplacement of the Late Hesperian lavas on Isidis Planitia. The trend of the faults at Amenthes, like many thrust faults at the dichotomy boundary, parallels the boundary itself. Schultz and Watters used a dislocation modeling program to match surface topography and vertical offset of the scarp at Amenthes Rupes, varying the dip and depth of faulting, assuming a slip of 1.5 km on the fault. They modeled faulting below Amenthes Rupes as having a dip of between 25 and 30 degrees and a depth of 25 to 35 km, based on the best match to topography. Assuming a 25 degree dip and surface measurements of vertical offset of between 0.3 and 1.2 km, Watters later estimated the maximum displacement on the Amenthes Rupes fault to be 2.90 km. However, these studies did not determine the geometry of the thrust using quantitative constraints that included shortening estimates. Amenthes Rupes deforms large preexisting impact craters. We use these craters to constrain shortening across the scarp and combine this with vertical separation to infer fault geometry. Fault dip was also estimated using measurements of scarp morphology. Measurements were based on 460 m (1/128 per pixel) digital elevation data from the Mars Orbiter Laser Altimeter (MOLA), an instrument on the Mars Global Surveyor (MGS) satellite.

Vidal, A.; Mueller, K. M.; Golombek, M. P.

2005-01-01

240

Testing and Lubrication for Single Race Bearings  

Energy Technology Data Exchange (ETDEWEB)

Three ES and H-compatible lubricants (Environment, Safety and Health) for single race bearing applications and one hybrid-material single race bearings were evaluated and compared against single race bearings with trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon), which is an ozone-depleting solvent. Vydax has been used as a bearing lubricant in stronglink mechanisms since 1974. Hybrid bearings with silicon nitride balls and molded glass-nylon-Teflon retainers, bearings lubricated with titanium carbide (TiC) on the balls, bearings lubricated with sputtered MoS{sub 2} on races and retainers, and bearings lubricated with electrophoretically deposited MoS{sub 2} were evaluated. The bearings were maintained in a preloaded state in bearing cartridges during cycling and vibration tests. Bearings with electrophoretically deposited MoS{sub 2} performed as well as bearings lubricated with Vydax and were the best performing candidate. All candidates were suitable for low preload applications. Bearings with TiC coated balls and bearings lubricated with sputtered MoS{sub 2} on the races and retainers performed well at high preloads, though not as well as bearings lubricated with electrophoretic deposition of MoS{sub 2}. Bearings with silicon nitride balls were not suitable for high preload applications.

Steinhoff, R.G.

1998-03-04

 
 
 
 
241

Dynamic friction and wear in a planar-contact encapsulated microball bearing using an integrated microturbine  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The demonstration and characterization of a novel planar-contact encapsulated microball bearing using a radial in-flow microturbine are presented. Stable operation of the air-driven silicon microturbine is shown for over 1 000 000 revolutions at speeds, pressure drops, and flow rates of up to 10 000 r/min, 0.45 lbf/in2, and 3.5 slm, respectively. Incorporation of a gas thrust plenum using a novel packaging scheme has enabled comprehensive spin-down friction characterization of the encapsulate...

Mccarthy, Matthew; Waits, C. Mike; Ghodssi, Reza

2008-01-01

242

Adaptive Control of a Transport Aircraft Using Differential Thrust  

Science.gov (United States)

The paper presents an adaptive control technique for a damaged large transport aircraft subject to unknown atmospheric disturbances such as wind gust or turbulence. It is assumed that the damage results in vertical tail loss with no rudder authority, which is replaced with a differential thrust input. The proposed technique uses the adaptive prediction based control design in conjunction with the time scale separation principle, based on the singular perturbation theory. The application of later is necessitated by the fact that the engine response to a throttle command is substantially slow that the angular rate dynamics of the aircraft. It is shown that this control technique guarantees the stability of the closed-loop system and the tracking of a given reference model. The simulation example shows the benefits of the approach.

Stepanyan, Vahram; Krishnakumar, Kalmanje; Nguyen, Nhan

2009-01-01

243

Minimum Thrust Load Control for Floating Wind Turbine  

DEFF Research Database (Denmark)

â?? Offshore wind energy capitalizes on the higher and less turbulent wind at sea. Shallow water sites are profitable for deployment of monopile wind turbines at water depths of up to 30 meters. Beyond 30 meters, the wind is even stronger and less turbulent. At these depths, ï¬?oating wind turbines become profitable, capable of accessing unexploited wind resources while reaching regions of new consumers. However, ï¬?oating 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 ï¬?oating 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.

Christiansen, Søren; Bak, Thomas

2012-01-01

244

Procedure for utilizing the lift and thrust forces of ornithopters  

Science.gov (United States)

This procedure is distinguished by two beating wings which together describe, in space, a succession of interlaced triangles. On these wings, whose incidence varies automatically, identical forces are exerted: simultaneous lift and thrust when they make their descent, which is inclined toward the front of the craft, and lift alone when they make their ascent, which is inclined toward the rear of the craft and follows a slide horizontal movement. A mechanical device makes these movements possible. It includes: two wings with hollow profiles, connected by a framework located above a rigid frame and attached to it by bars with joints. These bars are moved with control rods which gear down the drive force. A mechanism with elastic bands or springs automatically varies the incidence of the wings.

Bezard, C.

1985-01-01

245

Thrust Measurements in Ballistic Pendulum Ablative Laser Propulsion Experiments  

International Nuclear Information System (INIS)

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

2008-04-28

246

Real-time seam tracking for rocket thrust chamber manufacturing  

Energy Technology Data Exchange (ETDEWEB)

A sensor-based control approach for real-time seam tracking of rocket thrust chamber assemblies has been developed to enable automation of a braze paste dispensing process. This approach utilizes a non-contact Multi-Axis Seam Tracking (MAST) sensor to track the seams. Thee MAST sensor measures capacitance variations between the sensor and the workpiece and produces four varying voltages which are read directly into the robot controller. A PID control algorithm which runs at the application program level has been designed based upon a simple dynamic model of the combined robot and sensor plant. The control algorithm acts on the incoming sensor signals in real-time to guide the robot motion along the seam path. Experiments demonstrate that seams can be tracked at 100 mm/sec within the accuracy required for braze paste dispensing.

Schmitt, D.J.; Novak, J.L. [Sandia National Labs., Albuquerque, NM (United States); Starr, G.P. [New Mexico Univ., Albuquerque, NM (United States); Maslakowski, J.E. [Rockwell International Corp., Canoga Park, CA (United States). Rocketdyne Div.

1993-11-01

247

Input shaped large thrust maneuver with a tethered debris object  

Science.gov (United States)

In order to reduce the debris population in LEO, remediation is necessary. An active debris removal method is explored that utilizes fuel reserves on a recently launched upper stage to rendezvous with, and tether to, debris. The system's tethered dynamics are explored using a discretized tether model attached to six degree of freedom end bodies. The thrust output is shaped to remove the spectral energy at the natural frequencies of the tether, significantly reducing the post-burn relative motion between the vehicles. The sensitivity of the input shaping performance due to imperfect knowledge of the debris mass demonstrates that a double notch spanning multiple frequencies around the first mode is necessary to be robust to unknown debris mass. On-orbit simulations show that input shaping helps the tethered system achieve smooth oscillations about a gravity gradient alignment, reducing collision likelihood.

Jasper, Lee; Schaub, Hanspeter

2014-03-01

248

Thrust Stand Measurements of the Conical Theta Pinch FARAD Thruster  

Science.gov (United States)

It is found that the impulse of a pulsed inductive plasma thruster utilizing preionization is maximized for a particular ratio of the stored energy in the capacitor to the injected propellant mass. The fact that the impulse depends on the ratio of the initial stored energy to injected propellant mass agrees with previous current sheet studies, supporting the idea that a Townsend-like breakdown process strongly influences current sheet formation, and in turn, current sheet formation strongly affects the operational efficiency of the device. The optimum in half cone angle of the inductive coil can be explained in terms of a balance between the direct axial acceleration and the radial pinching contribution to thrust. From the trends in these data we conclude that operation at the correct ratio of capacitor energy to propellant mass is essential for efficient operation of pulsed inductive plasma thrusters employing a preionized propellant.

Hallock, Ashley K.; Polzin, Kurt A.

2010-01-01

249

Correlation of asperity contact-time fraction with elastohydrodynamic film thickness in a 20-millimeter-bore ball bearing  

Science.gov (United States)

Elastohydrodynamic film thicknesses and asperity contact-time fractions were measured for a 20 mm bore ball bearing by using the capacitance and conductance techniques. The bearing was thrust loaded to 90, 445, and 778 N. The corresponding maximum stresses on the inner race were 1.28, 2.09, and 2.45 GPa. The test speed ranged from 400 to 15,000 rpm. The test bearing was mist lubricated with a MIL-L-23699A turbine oil. The temperature was 27 C. The experimental results were correlated to give the percent film (no-contact-time fraction) as a function of measured film thickness. Measurements were made for three test series that represented the test bearing in various conditions of run-in. The measurements show that the percent film changes with bearing run-in time. The experimental results agreed well with theoretical predictions based on surface trace analysis for a new bearing. For the run-in state, they agreed with previously reported experimental results. The results show that asperity contact existed at a film thickness-roughness ratio lambda of 6.0 or less for a new bearing. After run-in, no asperity contact occurred at a lambda of 3.5 or greater.

Coy, J. J.

1979-01-01

250

Momentum Management Tool for Low-Thrust Missions  

Science.gov (United States)

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.

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

2010-01-01

251

Reverse migration of seismicity on thrusts and normal faults  

Science.gov (United States)

In this work, is analysed the control exerted by the stress axes orientation on the evolution of seismic sequences developing in compressive and extensional regime. According to the Anderson fault theory, the vertical stress is the minimum principal stress in compressional tectonic regimes, whereas it is the maximum principal stress in extensional regimes. Using Mohr diagrams and discussing the present knowledge about the distribution of vertical and horizontal stress with depth we show that, in absence of localised fluid overpressure, such changes imply that thrust and normal faults become more unstable at shallower and greater depths, respectively. These opposite mechanical behaviours predict, in a rather isotropic body, easier rupture at shallower level in compressional regimes later propagating downward. On the contrary, a first deep rupture propagating upward is expected in extensional regimes. This is consistent with observations from major earthquakes from different areas in the world. We show that the exceptions to downward migration along thrusts occur along steeply inclined faults and probably imply localised supra-hydrostatic fluid pressures. Moreover, we show that the inversion of the meaning of the lithostatic load has consequences also for the role of topography. High topography, increasing the vertical load, should inhibit earthquake development in compressional environments and should favour it in extensional settings. Although several factors, such as geodynamic processes, local tectonic features and rock rheology, are likely to control earthquake locations, stress distribution and tectonic regime, these model predictions are consistent with seismicity distribution in Italy, central Andes and Himalaya. In these areas, large to medium compressional earthquakes occur at the low elevation borders of compressional mountain belts, whereas large extensional earthquakes occur in correspondence to maximum elevations.

Carminati, E.; Doglioni, C.; Barba, S.

2004-05-01

252

Coseismic fault-related fold model, growth structure, and the historic multisegment blind thrust earthquake on the basement-involved Yoro thrust, central Japan  

Science.gov (United States)

We use high-resolution seismic reflection profiles, boring transects, and mapping of fold scarps that deform late Quaternary and Holocene sediments to define the kinematic evolution, subsurface geometry, coseismic behavior, and fault slip rates for an active, basement-involved blind thrust system in central Japan. Coseismic fold scarps on the Yoro basement-involved fold are defined by narrow fold limbs and angular hinges on seismic profiles, suggesting that at least 3.9 km of fault slip is consumed by wedge thrust folding in the upper 10 km of the crust. The close coincidence and kinematic link between folded horizons and the underlying thrust geometry indicate that the Yoro basement-involved fold has accommodated slip at an average rate of 3.2 ± 0.1 mm/yr on a shallowly west dipping thrust fault since early Pleistocene time. Past large-magnitude earthquakes, including an historic M˜7.7 event in A.D. 1586 that occurred on the Yoro blind thrust, are shown to have produced discrete folding by curved hinge kink band migration above the eastward propagating tip of the wedge thrust. Coseismic fold scarps formed during the A.D. 1586 earthquake can be traced along the en echelon active folds that extend for at least 60 km, in spite of different styles of folding along the apparently hard-linked Nobi-Ise blind thrust system. We thus emphasize the importance of this multisegment earthquake rupture across these structures and the potential risk for similar future events in en echelon active fold and thrust belts.

Ishiyama, Tatsuya; Mueller, Karl; Sato, Hiroshi; Togo, Masami

2007-03-01

253

Refolding of thin-skinned thrust sheets by active basement-involved thrust faults in the Eastern Precordillera of western Argentina  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Devastating earthquakes like the 1944 San Juan earthquake reflect active deformation in western Argentina. Although the earthquake caused considerable damage to San Juan, the source of the earthquake remains uncertain. Potential source faults occur in the thin-skinned fold-and-thrust belt Precordillera province and in the thick-skinned Sierras Pampeanas province, to the west and east, respectively of Sierra de Villicum, a thrust sheet in the eastern Precordillera northwest of San Juan. Sierra...

Meigs, A.; Krugh, W. C.; Schiffman, C.; Verge?s, Jaume; Ramos, V. A.

2006-01-01

254

Liquid oxygen cooled bearing ignition potential assessment  

Science.gov (United States)

Space Shuttle Main Engine High Pressure Oxygen Turbopump bearings have shown evidence of heavy oxidation on the surfaces of the balls and races. Extensive analyses were performed to assess the ignition potential in the bearing system during normal and off-nominal operation. Test programs and analyses were used to determine the bearing thermal condition and bearing material ignition characteristics.

Page, Arthur T.; Goode, Brian K.; Owen, James W.

1990-01-01

255

Wind turbine yaw control hydrostatic bearing system  

Energy Technology Data Exchange (ETDEWEB)

The technical advantages of hydrostatic bearings over conventional rolling contact sleuring ring bearings for supporting the nacelle of a horizontal axis wind turbine are studied. Two small hydrostatic bearings were manufactured for testing under operational conditions. Design and manufacturing methods were also developed for the commercial exploitation of such bearings. (UK)

NONE

1996-10-01

256

Thermal ground water flow systems in the thrust zone in southeastern Idaho  

Energy Technology Data Exchange (ETDEWEB)

The results of a regional study of thermal and non-thermal ground water flow systems in the thrust zone of southern Idaho and western Wyoming are presented. The study involved hydrogeologic and hydrochemical data collection and interpretation. Particular emphasis was placed on analyzing the role that thrust zones play in controlling the movement of thermal and non-thermal fluids.

Ralston, D.R.

1983-05-01

257

A structural analysis of the Moine Thrust Zone between Loch Eriboll and Foinaven, NW Scotland  

Science.gov (United States)

The northern part of the Moine Thrust Zone as exposed around the valley of Srath Beag, Sutherland was developed by thrusts propagating in the tectonic transport direction. Deformation on any particular thrust surface evolved from dominantly ductile to dominantly brittle with time. The foreland has been progressively accreted onto the overriding Moine thrust sheet by duplex formation, a process which has continuously folded the roof thrust and the rocks above its hanging-wall. Fold culminations and depression can be related to lateral ramps which may give the rocks above the hanging-wall a complex history of extensional and compressional strains normal to the transport direction. Folds within the thrust zone are laterally independent because they are controlled by short lived variations in deformation style on an evolving thrust footwall topography. Therefore there may be no correlation between structures across or along the thrust zone. This variation limits the construction of balanced cross sections as structure cannot be projected onto particular section lines.

Butler, Robert W. H.

258

Mathematical relation between the Hohmann transfer and continuous-low thrust Maneuvers  

Science.gov (United States)

Employed primarily by spacecraft with electric propulsion systems, spiral orbital transfers are characterized by continuous thrust throughout the maneuver. The ?V required to conduct a continuous-low-thrust spiral transfer can be determined if the limit of the ?V equation for a Hohmann transfer is evaluated as the number of consecutive Hohmann transfers, or burn frequency, approaches infinity.

Bettinger, Robert A.; Black, Jonathan T.

2014-03-01

259

Critical taper wedge mechanics of fold-and-thrust belts on Venus - Initial results from Magellan  

Science.gov (United States)

Examples of fold-and-thrust belts from a variety of tectonic settings on Venus are introduced. Predictions for the mechanics of fold-and-thrust belts on Venus are examined on the basis of wedge theory, rock mechanics data, and currently known conditions on Venus. The theoretical predictions are then compared with new Magellan data.

Suppe, John; Connors, Chris

1992-01-01

260

Molecular gas dynamics applied to low-thrust propulsion  

Science.gov (United States)

The Direct Simulation Monte Carlo method is currently being applied to study flowfields of small thrusters, including both the internal nozzle and the external plume flow. The DSMC method is employed because of its inherent ability to capture nonequilibrium effects and proper boundary physics in low-density flow that are not readily obtained by continuum methods. Accurate prediction of both the internal and external nozzle flow is important in determining plume expansion which, in turn, bears directly on impingement and contamination effects.

Zelesnik, Donna; Penko, Paul F.; Boyd, Iain D.

1993-01-01

 
 
 
 
261

Thrust fault systems of the Nankai Trough accretionary wedge interpreted from 3-D seismic reflection images  

Science.gov (United States)

In 1999 we acquired a large volume of 3-D seismic reflection data to image the deformational structure of the Nankai Trough accretionary wedge that forms due to the subduction of the Philippine Sea plate beneath Japan. We imaged an 8 x 80 km2 area south of the Muroto Peninsula offshore Shikoku Island, southwestern Japan, from the trench across the seaward most 70 km of the accretionary wedge. These data have been processed with 3-D prestack time migration and in selected locations with 3-D prestack depth migration. The 3-D volume reveals complex thrust fault systems that have offset and displaced stratigraphic horizons at a range of scales from meters to kilometers. We identify four distinctive fault systems with increasing scale as: 1) small thrusts with lengths of 100 - 500 m and offsets of 10 - 100 m, many of these lie immediately adjacent and parallel to the primary accretionary wedge thrust system (#2 below) or are conjugate thrusts (backthrusts), 2) the primary thrusts of the accretionary wedge imbricate thrust system, which initiate at the deformation front and develop into 1 - 5 km long thrusts with displacements of 100 - 1000 m, 3) thrusts (out-of-sequence) that develop after the initial imbricate thrust system develops (#2 above), these are > 5 km long, have a shallower dip than the imbricate thrust system and intersect the imbricate thrust system, and 4) the main plate-boundary thrust, or décollement, that lies at the base of the accretionary wedge, which can be traced from its initiation at the trench to > 50 km down into the subduction zone. Each of these thrust systems controls the accretionary wedge tectonics and influences the structure of the accretionary wedge in both the dip and strike directions. We will present evidence to show how these fault systems affect wedge tectonics. We will also show that surprisingly, the wedge thrust activity reacts to the regional stress pattern created by recent seamount subduction, centered 50 km northeast of the survey area, as much or more than the localized stress conditions produced by changes in the geometry of the décollement or the top of the subducting oceanic crust.

Bangs, N. L.; Gulick, S. P.; Shipley, T. H.; Moore, G. F.

2004-12-01

262

Superconductor bearings, flywheels and transportation  

International Nuclear Information System (INIS)

This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS–FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

2012-01-01

263

Superconductor bearings, flywheels and transportation  

Science.gov (United States)

This paper describes the present status of high temperature superconductors (HTS) and of bulk superconducting magnet devices, their use in bearings, in flywheel energy storage systems (FESS) and linear transport magnetic levitation (Maglev) systems. We report and review the concepts of multi-seeded REBCO bulk superconductor fabrication. The multi-grain bulks increase the averaged trapped magnetic flux density up to 40% compared to single-grain assembly in large-scale applications. HTS magnetic bearings with permanent magnet (PM) excitation were studied and scaled up to maximum forces of 10 kN axially and 4.5 kN radially. We examine the technology of the high-gradient magnetic bearing concept and verify it experimentally. A large HTS bearing is tested for stabilizing a 600 kg rotor of a 5 kWh/250 kW flywheel system. The flywheel rotor tests show the requirement for additional damping. Our compact flywheel system is compared with similar HTS-FESS projects. A small-scale compact YBCO bearing with in situ Stirling cryocooler is constructed and investigated for mobile applications. Next we show a successfully developed modular linear Maglev system for magnetic train operation. Each module levitates 0.25t at 10 mm distance during one-day operation without refilling LN2. More than 30 vacuum cryostats containing multi-seeded YBCO blocks are fabricated and are tested now in Germany, China and Brazil.

Werfel, F. N.; Floegel-Delor, U.; Rothfeld, R.; Riedel, T.; Goebel, B.; Wippich, D.; Schirrmeister, P.

2012-01-01

264

Design data for steadily loaded crown bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The performance of hydrodynamic journal bearings can be significantly affected by lubricant supply conditions (namely groove geometry and location, and supply pressure). The crown bearing is a particular type of journal bearing in which the supply groove is located on the load line. There are no comprehensive design data available specifically applicable to this type of bearing. In this paper design charts of load capacity, power loss and flow rate for crown bearings are presented. They have ...

Claro, Jose? Carlos Pimenta; Miranda, A. S.

1993-01-01

265

Development of porous-ceramic hydrostatic bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Porous-ceramic hydrostatic bearings have been recently developed. These bearings have demonstrated an exceptional overall performance when compared with conventional technology bearings. However, despite all the benefits, porous-ceramic hydrostatic bearings have yet to find widespread acceptance due to the problems found in tailoring the bearings geometry and size to suit precision engineering applications, while producing porous-structures with consistent and reproducible p...

Durazo Cardenas, Isidro Sergio

2003-01-01

266

Development of porous ceramic air bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Porous air bearings enjoy some important advantages over conventional air bearing types such as increased load carrying capacity, higher stiffness and improved damping. However, these types of bearings have yet to find widespread acceptance due to problems with obtaining materials with consistent permeability, instability issues relating to the volume of gas trapped at the bearing surface in the pores, and manufacturing the bearing without altering the permeability. Using...

Roach, Christopher James

2001-01-01

267

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

Science.gov (United States)

We present the geometry, kinematics and mechanics of large-scale thrusting in the West Kunlun Shan and the southwest Tarim Basin, which is associated with the northward motion of Tibet. The great frontal structure is the ~230km long intact bedding parallel Hotian thrust sheet composed of strata of the Tarim Basin lying above a regional gypsum horizon at the base of the Cenozoic sequence. The toe of the Hotian thrust sheet steps steeply to the surface two thirds of the way across the basin forming the Selibuya-Mazartag hills in the sand desert. The Hotan thrust constitutes one of the longest active intact thrust sheets in the world, showing little internal deformation, however at its back it steps down to a Cambrian detachment at the base of the Paleozoic below a belt of complex high-amplitude anticlines near the front of the West Kunlun Shan, which display break-forward imbricate and wedge structure. More interior, steep reverse faults such as the Tieklik thrust bring older strata to the surface, including Paleozoic basement. The Cambrian detachment also extends northward under the Tarim basin with minor hanging-wall deformation that warps the Hotian Thrust sheet locally, causing the development of growth strata in the Hotian thrust sheet that providesa quantitative record of its motion over these warps. Seismic profiles in the southwest Tarim basin 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(from Zheng et al., 2000)and traced throughout the seismic grid. The bottom of the growth strata is dated at 3.6 Ma indicating a Pliocene and younger age of thrusting and folding in the southwest Tarim Basin. Structural restoration suggests minimum shortening greater than 35km. The Tieklik thrust consumed at least 10 km in early Pliocene. The fold-and-thrust belts of the southwest Tarim basin shortened >25km in late Pliocene and Pleistocene. Some slip propagated northward into the inland of Tarim basin and developed the thrust surface rupture zone at Selibuya-Mazartag. The overall shortening rate is ~10 mm/yr in the fold-and-thrust belt of the southwest Tarim basin since Pliocene. The strength of the gypsum detachment of the 240 km long Hotian thrust sheet can be estimated from the tapered geometry. Using wedge theory (Suppe 2007) we find that the ratio of critical wedge strength W to detachment strength F is equal to the detachment dip in radians for a wedge of zero surface slope. The current dip of the Hotian detachment is 0.08° or 0.014. Typical wedge strengths are in the range 0.5-1, therefore based on the lack of internal deformation we estimate an upper bound on the strength of the gypsum detachment, expressed as an exceedingly weak effective friction coefficient of less than ~0.0005-0.0015.

Wang, Xin; Suppe, John; Liang, Hang; He, Dengfa

2014-05-01

268

Precursory changes in ionosphere immediately before mega-thrust earthquakes  

Science.gov (United States)

Heki [2011] reported that positive anomalies of ionospheric Total Electron Content (TEC) appeared about 1 hour before the 2011 Tohoku-Oki earthquake (Mw9.0) by using the Japanese dense GPS array. Here we show that similar anomalies commonly precede mega-thrust earthquakes, i.e. the 2004 Sumatra-Andaman (Mw9.2), 2010 Maule (Mw8.8), 2012 Off-Northern Sumatra (Mw8.6), 2007 Bengkulu (Mw8.5), and 1994 Hokkaido-Toho-Oki earthquakes (Mw8.3). So far, the 2005 Nias earthquake (Mw8.6) is the only over-Mw8.5 earthquake without clear preseismic TEC changes (TEC data then were disrupted by severe plasma bubble signatures). The anomalies started 90-40 minutes before earthquakes. They are positive and smaller negative anomalies often accompanied. The centers of the positive anomalies sometimes shift southward (northward) from the ruptured faults in the northern (southern) hemispheres. The attached figure shows the slant TEC changes observed by Chilean GPS stations over 2.5-hours period encompassing the 2010 Maule earthquake. Clear onsets of the TEC anomalies can be seen about 40 minutes prior to the mainshock. TEC increases may occur irrespective of earthquakes. We studied geomagnetic activities before and after these mega-thrust events; the 2010 Maule and the 2007 Bengkulu earthquakes occurred during geomagnetic quiescence and the others occurred during more or less disturbed periods. We analyzed the TEC time series of the same satellite and station pairs over 120 days before and after the 2011 Tohoku-oki and 2007 Bengkulu earthquakes. Relatively large TEC changes with similar spatial and temporal scales to the preseismic anomalies occur from time to time, many of which are due to large-scale traveling ionospheric disturbances from the auroral oval. In short, they are not rare but not so often, i.e. we can rule out with confidence the possibility that the TEC anomalies before all these six earthquakes are fortuitous. We also review observables other than GPS-TEC showing similar preseismic changes, and suggest that f0Es at Kokubunji and geomagnetic field in NE Japan showed interesting behaviors immediately before the 2011 Tohoku-oki earthquake.

Heki, K.; Cahyadi, M. N.

2012-12-01

269

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

International Nuclear Information System (INIS)

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)

1980-01-01

270

VPS Process for Copper Components in Thrust Chamber Assemblies  

Science.gov (United States)

For several years, NASA's Marshall Space Flight Center (MSFC) has been working with Plasma Processes, Inc., (PPI) to fabricate thrust chamber liners with GRCop-84. Using the vacuum plasma spray (VPS) process, chamber liners of a variety of shapes and sizes have been created. Each has been formed as a functional gradient material (FGM) that creates a unique protective layer of NiCrAlY on the GRCop-84 liner s hot wall surface. Hot-fire testing was successfully conducted on a subscale unit to demonstrate the liner's durability and performance. Similar VPS technology has also been applied to create functional gradient coatings (FGC) on copper injector faceplates. Protective layers of NiCrAlY and zirconia were applied to both coaxial and impinging faceplate designs. Hot-fire testing is planned for these coated injectors in April 2005. The resulting material systems for both copper alloy components allows them to operate at higher temperatures with improved durability and operating margins.

Elam, Sandra; Holmes, Richard; Hickman, Robert; McKechnie, Tim; Thom, George

2005-01-01

271

Radiation effects in low-thrust orbit transfers  

International Nuclear Information System (INIS)

A low-thrust orbit transfer vehicle (OTV) and its payload must be designed to survive in the near-Earth radiation environment for a much longer duration than a conventional upper stage. This paper examines the effects of natural radiation on OTV's using data that have become available since 1991 from the CRRES and APEX satellites. Dose rates for microelectronics in LEO-to-GEO missions are calculated for spiral orbit raising and for multi-impulse transfers. Semiconductor devices that are shielded by less than 2.5 mm of aluminum (0.69 g/cm2) are inappropriate for spiral transfers, because they require hardness levels >100 krad (Si). Shield thicknesses of 6-12 mm reduce this requirement to about 10 krad (Si), which is still an order of magnitude higher than the radiation dose in a 10-year mission at GEO with similar shielding. The dose for a multi-impulse LEO-to-GEO transfer is about 10 times smaller than for a spiral transfer. Estimates of single event upset rates and photovoltaic array degradation are also provided

1998-01-15

272

SOURCE TERM TARGETED THRUST FY 2005 NEW START PROJECTS  

Energy Technology Data Exchange (ETDEWEB)

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.

NA

2005-10-05

273

Variable Flavor Number Scheme for Final State Jets in Thrust  

CERN Document Server

We present results for mass effects coming from secondary radiation of heavy quark pairs related to gluon splitting in the thrust distribution for e+e- collisions. The results are given in the dijet limit where the hard interaction scale and the scales related to collinear and soft radiation are widely separated. We account for the corresponding fixed-order corrections at O(alpha_s^2) and the summation of all logarithmic terms related to the hard, collinear and soft scales as well as the quark mass at N3LL order. We also remove the O(Lambda_QCD) renormalon in the partonic soft function leading to an infrared evolution equation with a matching condition related to the massive quark threshold. The quark mass can be arbitrary, ranging from the infinitely heavy case, where decoupling takes place, down to the massless limit where the results smoothly merge into the well known predictions for massless quarks. Our results are formulated in the framework of factorization theorems for e+e- dijet production and provide...

Pietrulewicz, Piotr; Hoang, Andre H; Jemos, Ilaria; Mateu, Vicent

2014-01-01

274

SOURCE TERM TARGETED THRUST FY 2005 NEW START PROJECTS  

International Nuclear Information System (INIS)

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

2005-01-01

275

Static Thrust and Vectoring Performance of a Spherical Convergent Flap Nozzle with a Nonrectangular Divergent Duct  

Science.gov (United States)

The static internal performance of a multiaxis-thrust-vectoring, spherical convergent flap (SCF) nozzle with a non-rectangular divergent duct was obtained in the model preparation area of the Langley 16-Foot Transonic Tunnel. Duct cross sections of hexagonal and bowtie shapes were tested. Additional geometric parameters included throat area (power setting), pitch flap deflection angle, and yaw gimbal angle. Nozzle pressure ratio was varied from 2 to 12 for dry power configurations and from 2 to 6 for afterburning power configurations. Approximately a 1-percent loss in thrust efficiency from SCF nozzles with a rectangular divergent duct was incurred as a result of internal oblique shocks in the flow field. The internal oblique shocks were the result of cross flow generated by the vee-shaped geometric throat. The hexagonal and bowtie nozzles had mirror-imaged flow fields and therefore similar thrust performance. Thrust vectoring was not hampered by the three-dimensional internal geometry of the nozzles. Flow visualization indicates pitch thrust-vector angles larger than 10' may be achievable with minimal adverse effect on or a possible gain in resultant thrust efficiency as compared with the performance at a pitch thrust-vector angle of 10 deg.

Wing, David J.

1998-01-01

276

Fuzzy control of magnetic bearings  

Science.gov (United States)

The use of an adaptive fuzzy control algorithm implemented on a VLSI chip for the control of a magnetic bearing was considered. The architecture of the adaptive fuzzy controller is similar to that of a neural network. The performance of the fuzzy controller is compared to that of a conventional controller by computer simulation.

Feeley, J. J.; Niederauer, G. M.; Ahlstrom, D. J.

1991-01-01

277

Effects of vibration and shock on the performance of gas-bearing space-power Brayton cycle turbomachinery. 2: Sinusoidal and random vibration  

Science.gov (United States)

The vibration response of a gas-bearing rotor-support system was analyzed experimentally documented for sinusoidal and random vibration environments. The NASA Brayton Rotating Unit (BRU), 36,000 rpm; 10 KWe turbogenerator; was subjected in the laboratory to sinusoidal and random vibrations to evaluate the capability of the BRU to (1) survive the vibration levels expected to be encountered during periods of nonoperation and (2) operate satisfactorily (that is, without detrimental bearing surface contacts) at the vibration levels expected during normal BRU operation. Response power spectral density was calculated for specified input random excitation, with particular emphasis upon the dynamic motions of the thrust bearing runner and stator. A three-mass model with nonlinear representation of the engine isolator mounts was used to calculate axial rotor-bearing shock response.

Tessarzik, J. M.; Chiang, T.; Badgley, R. H.

1973-01-01

278

Performance of 40-millimeter-bore ball bearings with lead- and lead-alloy-plated retainers in liquid hydrogen at 1.2 million DN  

Science.gov (United States)

Forty-millimeter-bore ball bearings with lead- and lead-alloy-coated retainers were operated in liquid hydrogen at 30,000 rpm under a thrust load of 1780 N (400 lb.) Four different substrate materials were used for the retainer. Longer bearing run times were achieved with a lead-tin-copper alloy coating plated onto a leaded-bronze material (22.5 hr) and an aluminum-bronze alloy (19.3 hr). One bearing with a pure lead coating achieved the desired objective of 10 hr. This bearing had an aluminum - bronze substrate retainer and ran successfully for 12.4 hr. Additions of antimony to the lead provided an alloy coating with better wear resistance than pure lead; however, this coating was abrasive to the outer-race lands.

Brewe, D. E.; Wisander, D. W.; Scribbe, H. W.

1972-01-01

279

Climate Change, Polar Bears and their management  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This is a literature study of polar bears in the context of climate change: what kind of creatures are polar bears, what are the main interpretations of current climate change, how might the polar bear adapt to these changes (feeding strategies) and how are the bears being managed (hunting)? These are relevant questions , since climate change is on the agenda, and polar bears being the apex predators of the Arctic are a key representation of the wildlife there. The third element of polar bear...

Derenchenko, Liza

2010-01-01

280

Tribo-characteristics of self-lubricating ball bearings for the LE-7 liquid hydrogen rocket-turbopump  

Energy Technology Data Exchange (ETDEWEB)

The tribo characteristics of self-lubricating 40-mm-bore ball bearings with a retainer of glass cloth-polytetrafluoroethylene (PTFE) laminate, which has elliptical pockets with a large pocket clearance, were tested under thrust loads at speeds up to 50,000 rpm, 2 million DN, in liquid hydrogen (LH2) and in liquid nitrogen (LN2). During testing, the bearing torque, outer-race temperature, and electric resistance between the inner and outer races were monitored to verify the formation and rupture of a PTFE transfer film. Testing showed that the bearings having the elliptical retainer pockets were superior to the conventional bearings with circular pockets. It was determined that, at the maximum inner race spinning velocity of about 5 m/s, a PTFE transfer film could sustain the maximum Hertz stress, up to about 2000 N/sq mm, in LH2, without severe film rupture resulting in bearing seizure. In LN2, the critical load capacity of PTFE transfer film with bearing seizure was about 2700 N/sq mm. 10 refs.

Nosaka, Masataka; Oike, Mamoru; Kikuchi, Masataka; Kamijo, Kenjiro; Tajiri, Masanori (NASDA, Kakuda Propulsion Center (Japan) National Aerospace Lab., Kakuda (Japan) NTN Corp., Aerospace Bearing Engineering Dept., Kuwana (Japan))

1993-07-01

 
 
 
 
281

Episodic glacially derived thrusts: a case study from the central North Sea Basin  

Science.gov (United States)

An extensive survey of 2D seismic in the central North Sea has revealed a series of thrusts within glacial sediments on the western flank of the Dogger Bank. The tectonic movement is evidenced by both imbricated thrust faults and 'pop-up' structures suggesting lateral compression of the sediment sequence. The closely spaced (100m) sparker profiles provide an opportunity to examine a glacial process whose geometry is normally difficult to assess from surface exposures. Initial studies suggest the thrusts extending to near seabed indicate eastward movement from one of two decollement surfaces located up to 200m below seabed. The structures affect sediments deposited since the Last Glacial Maximum (e.g. Bolders Bank Formation). However, the lower decollement surface is located with pre-glacial deltaic deposits and it is considered that hydrogeological controls have determined the surfaces upon which the movement occurs. The thrust structures are mapped over 100km2 with thrust planes 200-500m apart. Individual thrust planes have a width of up to 6km and may extend 2km upwards from the decollement surface to the seabed. They can be mapped in groups with slightly different alignments suggesting that the process causing these features to form was repeated several times, possibly at an oscillating ice-margin. The direction of movement is from the west, with ice belonging to the British and Irish Ice Sheet. The thrusting may have been caused by sub-glacial, ice marginal or pro-glacial processes, or a combination of these at a fluctuating ice-margin. Although the thrusts extend upwards to near seabed there is no apparent seabed morphological expression, suggesting that the expected topography of broad ridges aligned along the thrust surfaces has been eroded by later glacial or periglacial erosion or the subsequent Holocene marine transgression.

Cotterill, C.; Ruiter, A.; Dove, D.; Long, D.; James, L.; Forsberg, C.

2013-12-01

282

A METHOD OF COMPUTER CALCULATION OF AXIAL THRUST AND INTERNAL LEAKAGE IN CENTRIFUGAL PUMPS  

Directory of Open Access Journals (Sweden)

Full Text Available A simple method of calculation of radial pressure distribution on a disc rotating in a casing and then the axial thrust in centrifugal pumps is presented. The method is based on integral relations and allows to estimate rapidly the axial thrust value with accuracy sufficient for technical applications (the error less than 15%. The method allows to compute simultaneously Internal leakage losses in centrifugal pumps. The presented method may also be useful for the calculation of the pressure distribution and the axial thrust in other rotating machines, such as compressors, gas turbines, water turbines, hydraulic torque convertors and paper-pulp mills.

Waldemar J?dral

1991-01-01

283

Technical assessment of Engineering`s Manufacturing Technology Thrust Area at Lawrence Livermore National Laboratory  

Energy Technology Data Exchange (ETDEWEB)

This document investigates the connection between the Manufacturing Technology Thrust Area and its market and concludes that the connection should include the programs internal to LLNL and customers outside of LLNL. The thrust area`s existing mission is reviewed and while it remains relevant to the future, it is too broad for the assigned resources. The scope of the thrust area`s mission is therefore narrowed to more specifically address precision in manufacturing. The course to pursue the new focus is plotted, and the projects for FY95 are briefly discussed.

Blaedel, K.L.

1995-07-27

284

Low eddy loss axial hybrid magnetic bearing with gimballing control ability for momentum flywheel  

International Nuclear Information System (INIS)

For a magnetically suspended momentum flywheel (MSMF), the spinning rotor can be tilted by a pair of the presented axial hybrid magnetic bearing (AHMB) with eight poles and rotates around the radial axes to generate a large torque to maneuver the spacecraft. To improve the control performance and gimballing control ability of the AHMB, characteristics such as magnetic suspension force, angular stiffness and tilting momentum are researched. These segmented stator poles cause the magnetic density in the thrust rotor plate to be uneven unavoidably and the rotational loss is large at high speed, but we optimized the stator poles configuration and caused the thrust rotor plate formed by bulk DT4C and laminated material to make the magnetic density in the thrust rotor plate change less and be smoother. Laminated material such as 1J50 film with a thickness of 0.1 mm can make the variation of the magnetic density in DT4C become very small and the eddy loss of it be negligible, but the stress produced in the “O” shape stacks by reeling has a bad effect on its power loss. Nanocrystalline can reduce eddy losses and is not affected by the reeling process. Based on the AHBM consisting of the stator with eight improved poles and the presented thrust rotor plate with DT4 and nanocrystalline, the rotational loss of 5-DOF magnetically suspended momentum flywheel with angular momentum of 15 N m s at 5000 rpm has reduced from 23.4 W to 3.2 W, which proved that this AHMB has low eddy loss for the gimballing control ability. - Highlights: ? Control methods of rotor driven by AHMBs and their characteristics are researched. ? Optimized stator and rotor of AHMB reduce its eddy losses greatly. ? Presented the factors affecting the eddy losses of AHMBs. ? The good performances of AHMB with low eddy loss are proved by experiments.

2013-03-01

285

Low eddy loss axial hybrid magnetic bearing with gimballing control ability for momentum flywheel  

Science.gov (United States)

For a magnetically suspended momentum flywheel (MSMF), the spinning rotor can be tilted by a pair of the presented axial hybrid magnetic bearing (AHMB) with eight poles and rotates around the radial axes to generate a large torque to maneuver the spacecraft. To improve the control performance and gimballing control ability of the AHMB, characteristics such as magnetic suspension force, angular stiffness and tilting momentum are researched. These segmented stator poles cause the magnetic density in the thrust rotor plate to be uneven unavoidably and the rotational loss is large at high speed, but we optimized the stator poles configuration and caused the thrust rotor plate formed by bulk DT4C and laminated material to make the magnetic density in the thrust rotor plate change less and be smoother. Laminated material such as 1J50 film with a thickness of 0.1 mm can make the variation of the magnetic density in DT4C become very small and the eddy loss of it be negligible, but the stress produced in the "O" shape stacks by reeling has a bad effect on its power loss. Nanocrystalline can reduce eddy losses and is not affected by the reeling process. Based on the AHBM consisting of the stator with eight improved poles and the presented thrust rotor plate with DT4 and nanocrystalline, the rotational loss of 5-DOF magnetically suspended momentum flywheel with angular momentum of 15 N m s at 5000 rpm has reduced from 23.4 W to 3.2 W, which proved that this AHMB has low eddy loss for the gimballing control ability.

Tang, Jiqiang; Sun, Jinji; Fang, Jiancheng; Shuzhi Sam, Ge

2013-03-01

286

Journal and Wave Bearing Impedance Calculation Software  

Science.gov (United States)

The wave bearing software suite is a MALTA application that computes bearing properties for user-specified wave bearing conditions, as well as plain journal bearings. Wave bearings are fluid film journal bearings with multi-lobed wave patterns around the circumference of the bearing surface. In this software suite, the dynamic coefficients are outputted in a way for easy implementation in a finite element model used in rotor dynamics analysis. The software has a graphical user interface (GUI) for inputting bearing geometry parameters, and uses MATLAB s structure interface for ease of interpreting data. This innovation was developed to provide the stiffness and damping components of wave bearing impedances. The computational method for computing bearing coefficients was originally designed for plain journal bearings and tilting pad bearings. Modifications to include a wave bearing profile consisted of changing the film thickness profile given by an equation, and writing an algorithm to locate the integration limits for each fluid region. Careful consideration was needed to implement the correct integration limits while computing the dynamic coefficients, depending on the form of the input/output variables specified in the algorithm.

Hanford, Amanda; Campbell, Robert

2012-01-01

287

Development of sputtered techniques for thrust chambers, task 1. [evaluation of filler materials for regeneratively cooled thrust chambers  

Science.gov (United States)

Filler materials proposed for use in the sputter fabrication regeneratively cooled thrust chambers were evaluated. Low melting castable alloys, CERROBEND. CERROCAST, and CERROTRU, slurry applied SERMETEL 481 and flame-sprayed aluminum were investigated as filler materials. Sputter deposition from a cylindrical cathode inverted magnestron was used to apply an OFHC copper closeout layer to filled OFHC copper ribbed-wall cylindrical substrates. The sputtered closeout layer structure was evaluated with respect to filler material contamination, predeposition machining and finishing operations, and deposition parameters. The application of aluminum by flame-spraying resulted in excessiver filler porosity. Though the outgassing from this porosity was found to be detrimental to the closeout layer structure, bond strengths in excess of 10,500 psi were achieved. Removal of the aluminum from the grooves was readily accomplished by leaching in a 7.0 molar solution of sodium hydroxide at 353 K. Of the other filler materials evaluated, CERROTRU was found to be the most suitable material with respect to completely filling the ribbed-wall cylinders and vacuum system compatibility. However, bond contamination resulted in low closeout layer bond strength with the CERROTRU filler. CERROBEND, CERROCAST, and SERMETEL 481 were found to be unacceptable as filler materials.

Mullaly, J. R.; Schmid, T. E.; Hecht, R. J.

1974-01-01

288

Effects of bearing deadbands on bearing loads and rotor stability  

Science.gov (United States)

A generic model of a turbopump, simplified to bring out these effects is examined. This model demonstrates that bearing deadbands which are of the same order of magnitude or larger than the center-of-mass offset of a rotor due to mass imbalances cause significantly different dynamic behavior than would be expected of a linear, dynamical system. This fundamentally nonlinear behavior yields altered stability characteristics and altered bearing loading tendencies. It is shown that side forces can enhance system stability in the small, i.e., as long as the mass imbalance does not exceed some thresholds value or as long as no large, impulsive disturbances cause the motion to depart significantly from the region of stability. Limit cycles are investigated in this report and techniques for determining these limit cycles are developed. These limit cycles are the major source of bearing loading and appear in both synchronous and nonsynchronous forms. The synchronous limit cycles are driven by rotor imbalances. The nonsynchronous limit cycles (also called subsynchronous whirls) are self-excited and are the sources of instability.

1984-01-01

289

Hunting for 'bears' in the backyard  

Science.gov (United States)

This Micscape Magazine article offers practical hints about how to collect and study tardigrades, or water bears, from mosses in your backyard. It features a general introduction of water bears, a video, and a section of references for further reading.

Walker, Dave; Magazine, Micscape

290

A Preliminary Foil Gas Bearing Performance Map  

Science.gov (United States)

Recent breakthrough improvements in foil gas bearing load capacity, high temperature tribological coatings and computer based modeling have enabled the development of increasingly larger and more advanced Oil-Free Turbomachinery systems. Successful integration of foil gas bearings into turbomachinery requires a step wise approach that includes conceptual design and feasibility studies, bearing testing, and rotor testing prior to full scale system level demonstrations. Unfortunately, the current level of understanding of foil gas bearings and especially their tribological behavior is often insufficient to avoid developmental problems thereby hampering commercialization of new applications. In this paper, a new approach loosely based upon accepted hydrodynamic theory, is developed which results in a "Foil Gas Bearing Performance Map" to guide the integration process. This performance map, which resembles a Stribeck curve for bearing friction, is useful in describing bearing operating regimes, performance safety margins, the effects of load on performance and limiting factors for foil gas bearings.

DellaCorte, Christopher; Radil, Kevin C.; Bruckner, Robert J.; Howard, S. Adam

2006-01-01

291

Use of Interstate Passageways by Black Bears.  

Science.gov (United States)

Vehicle collisions account for up to forty black bear (Ursus americanus) deaths per year in Tennessee. Historically, a relatively high number of bear deaths have occurred on Interstate Highway 40 between mile marker 440 and the North Carolina state line. ...

F. T. Manen A. B. Coley M. R. Pelton

1995-01-01

292

Alex the Bear Goes to Child Care  

Medline Plus

Full Text Available ... Alex the Bear Meet Alex the Bear, a new friend of Child Care Aware® Going to child care for the first time or entering a new child care setting can be a daunting experience ...

293

Rolling Element Bearing Stiffness Matrix Determination (Presentation)  

Energy Technology Data Exchange (ETDEWEB)

Current theoretical bearing models differ in their stiffness estimates because of different model assumptions. In this study, a finite element/contact mechanics model is developed for rolling element bearings with the focus of obtaining accurate bearing stiffness for a wide range of bearing types and parameters. A combined surface integral and finite element method is used to solve for the contact mechanics between the rolling elements and races. This model captures the time-dependent characteristics of the bearing contact due to the orbital motion of the rolling elements. A numerical method is developed to determine the full bearing stiffness matrix corresponding to two radial, one axial, and two angular coordinates; the rotation about the shaft axis is free by design. This proposed stiffness determination method is validated against experiments in the literature and compared to existing analytical models and widely used advanced computational methods. The fully-populated stiffness matrix demonstrates the coupling between bearing radial, axial, and tilting bearing deflections.

Guo, Y.; Parker, R.

2014-01-01

294

Cathodoluminescence, fluid inclusion and stable C-O isotope study of tectonic breccias from thrusting plane of a thin-skinned calcareous nappe  

Science.gov (United States)

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

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

2012-03-01

295

Technology development for indigenous water lubricated bearings  

International Nuclear Information System (INIS)

Water Lubricated Bearings (WLB) are used in various mechanisms of fuel handling systems of PHWRs and AHWR. Availability and random failures of these bearings was a major factor in refuelling operations. Indigenous development of these bearings was taken up and 7 types of antifriction bearings in various sizes (totaling 37 variants) for PHWR, AHWR and Dhruva applications were successfully developed. This paper deals with various aspects of WLB development. (author)

2010-01-01

296

Theory of the Ultimate Bearing Capacity Calculation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The traditional formula and calculation method for calculating the ultimate bearing capacity is not scientific. According to the research, the ultimate bearing capacity is equal to the real degree of the material and detection force product. Ultimate bearing capacity is not for the change of detecting the force. On the basis of this understanding, a new theory of the study bearing capacity of rock-soil and new methods is generated.

Chang Yi Wang; Ben Jun Wang; Shu Zun Jiang

2012-01-01

297

Theory of the Ultimate Bearing Capacity Calculation  

Directory of Open Access Journals (Sweden)

Full Text Available The traditional formula and calculation method for calculating the ultimate bearing capacity is not scientific. According to the research, the ultimate bearing capacity is equal to the real degree of the material and detection force product. Ultimate bearing capacity is not for the change of detecting the force. On the basis of this understanding, a new theory of the study bearing capacity of rock-soil and new methods is generated.

Chang Yi Wang

2012-01-01

298

Mercury in polar bears from Alaska  

Energy Technology Data Exchange (ETDEWEB)

Alaskan polar bear (Ursus maritimus) muscle and liver samples collected in 1972 were analyzed for total mercury. Bears north of Alaska had more mercury than bears west of Alaska. The only difference between young and adult animals was in the northern area where adults had more mercury in liver tissue than young animals. Levels were probably not high enough to be a serious threat to bears.

Lentfer, J.W.; Galster, W.A.

1987-04-01

299

Oil film pressure in hydrodynamic journal bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Hydrodynamic journal bearings are critical power transmission components that are carrying increasingly high loads because of the increasing power density in various machines. Therefore, knowing the true operating conditions of hydrodynamic journal bearings is essential to machine design. Oil film pressure is one of the key operating parameters describing the operating conditions in hydrodynamic journal bearings. Measuring the oil film pressure in bearings has been a demanding task and theref...

Valkonen, Antti

2009-01-01

300

Efficient invariant-manifold, low-thrust planar trajectories to the Moon  

Science.gov (United States)

Ballistic two-impulse trajectories to the Moon. Invariant-manifold and low-thrust trajectories to the Moon. Ballistic capture defined through attainable sets. Moon-perturbed Sun-Earth restricted three body problem statement.

Mingotti, G.; Topputo, F.; Bernelli-Zazzera, F.

2012-02-01

 
 
 
 
301

Physics of Thrust Prediction of the Solar Wind Electric Sail Propulsion System  

Science.gov (United States)

The electric solar wind sail is a newly invented way for using the solar wind dynamic pressure for providing thrust for a spacecraft. An electric sail spacecraft deploys long, thin, conducting tethers which are centrifugally stretched and kept in a high positive potential by an onboard electron gun. Scientifically, the essential problem is to predict the thrust force per unit length that the plasma stream exerts on the tether when the tether is kept in a 15-40 kV voltage. Recently, theoretical arguments were put forward which suggest that trapped electrons are almost completely absent from the electric sail. In view of these arguments, we make here the assumption that trapped electrons are absent and proceed to derive a simplified analytical thrust formula. This formula predicts about five times higher electric sail thrust than the original estimates which included trapped electrons.

Janhunen, P.

2010-09-01

302

Calculation of the thrust of a wave-powered marine propelling device  

International Nuclear Information System (INIS)

A scheme for calculating the thrust of a wave propelling device with limiters is proposed. The scheme can be extended to similar propelling devices with a more complex wing suspension or a more complex wing system

1995-11-01

303

Bearing-Mounting Concept Accommodates Thermal Expansion  

Science.gov (United States)

Pins or splines allow radial expansion without slippage. Design concept for mounting rotary bearing accommodates differential thermal expansion between bearing and any structure(s) to which bearing connected. Prevents buildup of thermal stresses by allowing thermal expansion to occur freely but accommodating expansion in such way not to introduce looseness. Pin-in-slot configuration also maintains concentricity.

Nespodzany, Robert; Davis, Toren S.

1995-01-01

304

Cool Polar Bears: Dabbing on the Texture  

Science.gov (United States)

In this article, the author describes how her second-graders created their cool polar bears. The students used the elements of shape and texture to create the bears. They used Monet's technique of dabbing paint so as to give the bear some texture on his fur.

O'Connell, Jean

2011-01-01

305

Tectonic History and Present-Day Deformation in the Zagros Fold-Thrust Belt  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis uses various approaches such as observation of satellite images, field investigations, analogue modeling and GPS measurements to constrain deformation of the basement and sedimentary cover of the Zagros fold-thrust belt in time and space. Focal mechanism solutions of most earthquakes indicate that deformation in the Zagros basement is due to shortening and thickening through numerous thrust faults. However, observations of strike-slip faulting recognized on satellite images imply ...

Hessami, Khaled

2002-01-01

306

Spillage Drag Estimation and Drag-Thrust Accounting for a Missile with Air Breathing Propulsion  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Air intake related aerodynamic aspects of an air breathing cruise missile are analyzed. A method for thrust and drag accounting is established, and, based on that, a partial simulation model for the thrust and intake spillage drag force of the missile is developed. The model combines wind tunnel data with analytical data. The intake spillage force has two components, pre entry force and cowl force. The pre entry force can be computed relatively easily, while the cowl force depends strongly up...

Olsen, Jon

2012-01-01

307

A particle bed reactor based NTP in the 112,500 N thrust class  

Energy Technology Data Exchange (ETDEWEB)

This paper discusses the application of a Particle bed Reactor (PBR) to a 112,500 N thrust Nuclear Thermal Propulsion (NTP) Engine. The method of analysis is described, followed by a presentation of the results. It is concluded that the PBR would result in a very competitive NTP engine. In addition, due to the high power densities possible with a PBR, high thrust/weight ratios are possible. This conclusion can be used to satisfy a variety of mission goals.

Ludewig, H.; Powell, J.R.; Lazareth, O.W. Jr.; Todosow, M.

1993-04-01

308

Low-Thrust-Enabled Highly-Non-Keplerian Orbits in Support of Future Mars Exploration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The technology of high-specific-impulse propulsion systems with low thrust is improving, opening up numerous possibilities for future missions applying continuous thrust to force a spacecraft out of a natural Keplerian orbit into a displaced non-Keplerian orbit. A systematic analysis is presented as to the applicability of highly-non-Keplerian orbits throughout the solar system. Thereafter, two applications of such orbits in support of future high-value-asset exploration of Mars are detailed:...

Macdonald, Malcolm; Mckay, Robert J.; Vasile, Massimiliano; Frescheville, Francois Bosquillon; Biggs, James; Mcinnes, Colin

2011-01-01

309

Design and development of a Micropound Extended Range Thrust Stand (MERTS)  

Science.gov (United States)

The development and operation of a micropound extended range thrust stand are considered. A cesium ion engine was tested in order to determine the measurement accuracy of the apparatus and to verify the calibration techniques used. The ion engine was tracked to within 5 percent. A check of the thrust stand calibration factor against that of the ion engine calibration factor showed a 4.3 percent difference.

Stark, K. W.

1972-01-01

310

Flow Field and Heat Transfer Analysis of Oxygen/Methane Liquid Rocket Engine Thrust Chambers  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study is devoted to the characterization and analysis of the ?ow ?eld and heat transfer in oxygen/methane liquid rocket engines. Attention is focused on the hot gas side of the thrust chamber, where highly energetic ?ows have to be managed en- suring the safe operation of the thrust chamber and of the entire engine. Di?erent technological solutions to handle such ?ows are here investigated by means of CFD numerical simulations. As a compromise between details and computation...

Betti, Barbara

2012-01-01

311

Ruthenium Catalysts Bearing Carboxylate Ligand  

Science.gov (United States)

Novel class of ruthenium complex bearing carboxylate function is described in this highlight. Chemical activation of 14 providing highly active metathesis catalysts is discussed. New catalytic system due to high affinity to silica gel allow to efficient catalyst removal to obtain colorless products with low ruthenium contamination. Unique structural motif allows to introduce new carboxylate and sulfonate derived ligands without use of silver or thallium salts. Latest results of metathesis with derivative of 14 in ionic liquids and aqueous emulsions are presented

Gawin, Rafa?; Grela, Karol

312

Fault Tolerant Homopolar Magnetic Bearings  

Science.gov (United States)

Magnetic suspensions (MS) satisfy the long life and low loss conditions demanded by satellite and ISS based flywheels used for Energy Storage and Attitude Control (ACESE) service. This paper summarizes the development of a novel MS that improves reliability via fault tolerant operation. Specifically, flux coupling between poles of a homopolar magnetic bearing is shown to deliver desired forces even after termination of coil currents to a subset of failed poles . Linear, coordinate decoupled force-voltage relations are also maintained before and after failure by bias linearization. Current distribution matrices (CDM) which adjust the currents and fluxes following a pole set failure are determined for many faulted pole combinations. The CDM s and the system responses are obtained utilizing 1D magnetic circuit models with fringe and leakage factors derived from detailed, 3D, finite element field models. Reliability results are presented vs. detection/correction delay time and individual power amplifier reliability for 4, 6, and 7 pole configurations. Reliability is shown for two success criteria, i.e. (a) no catcher bearing contact following pole failures and (b) re-levitation off of the catcher bearings following pole failures. An advantage of the method presented over other redundant operation approaches is a significantly reduced requirement for backup hardware such as additional actuators or power amplifiers.

Li, Ming-Hsiu; Palazzolo, Alan; Kenny, Andrew; Provenza, Andrew; Beach, Raymond; Kascak, Albert

2003-01-01

313

Aerospike thrust chamber program. [cumulative damage and maintenance of structural members in hydrogen oxygen engines  

Science.gov (United States)

An existing, but damaged, 25,000-pound thrust, flightweight, oxygen/hydrogen aerospike rocket thrust chamber was disassembled and partially repaired. A description is presented of the aerospike chamber configuration and of the damage it had suffered. Techniques for aerospike thrust chamber repair were developed, and are described, covering repair procedures for lightweight tubular nozzles, titanium thrust structures, and copper channel combustors. Effort was terminated prior to completion of the repairs and conduct of a planned hot fire test program when it was found that the copper alloy walls of many of the thrust chamber's 24 combustors had been degraded in strength and ductility during the initial fabrication of the thrust chamber. The degradation is discussed and traced to a reaction between oxygen and/or oxides diffused into the copper alloy during fabrication processes and the hydrogen utilized as a brazing furnace atmosphere during the initial assembly operation on many of the combustors. The effects of the H2/O2 reaction within the copper alloy are described.

Campbell, J., Jr.; Cobb, S. M.

1976-01-01

314

The Relationship Between Thrust Faults and Structural Fractures in the Tarim Basin, China  

Directory of Open Access Journals (Sweden)

Full Text Available It is a problem that how thrust faults control the distribution of structural fractures in the exploration and development of fracture oil-reservoirs. One section of fracture outcrops in Ordovician carbonites is measured in the north margin of Tarim Basin, and two sections cross the Fault I in the central Tarim Basin are measured and processed in the paper. The development rule of structural fractures can be depicted by the fracture density, and the fractures near fault can be divided into two regions: the fracture zone controlled by fault and the fracture zone controlled by regional stress field. The ratio of fault-controlled fracture zone width to the throw of thrust fault is a very important parameter to depict the development of fractures influenced by thrust fault. The ratio is related to the mechanism, scale and throw of the thrust fault. The width of fault-controlled fracture zone can be predicted based on the mechanism and throw of the thrust fault. It is very helpful to the exploration and development of fault-controlled fracture reservoirs.
Key words: Structural fractures; Fault-controlled fracture zone; Thrust fault; Fracture density

Jianfa Han

2011-12-01

315

Valve assembly having remotely replaceable bearings  

Energy Technology Data Exchange (ETDEWEB)

A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

Johnson, E.R.; Tanner, D.E.

1980-05-27

316

Valve assembly having remotely replaceable bearings  

Energy Technology Data Exchange (ETDEWEB)

A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings. 5 figs.

Johnson, E.R.; Tanner, D.E.

1980-05-27

317

Valve assembly having remotely replaceable bearings  

Energy Technology Data Exchange (ETDEWEB)

A valve assembly having remotely replaceable bearings is disclosed wherein a valve disc is supported within a flow duct for rotation about a pair of axially aligned bearings, one of which is carried by a spindle received within a diametral bore in the valve disc, and the other of which is carried by a bearing support block releasably mounted on the duct circumferentially of an annular collar on the valve disc coaxial with its diametrical bore. The spindle and bearing support block are adapted for remote removal to facilitate servicing or replacement of the valve disc support bearings.

Johnson, Evan R. (San Diego, CA); Tanner, David E. (Poway, CA)

1980-01-01

318

Polar Bears International : Wrangel Island, Russia  

Science.gov (United States)

This site describes the ongoing research of the polar bears in the Russian High Arctic. Wrangel Island with neighboring small island, Herald Island, are the key reproductive areas for the Chukchi-Alaskan polar bear population. Marine areas and Wrangel and Herald islands provide optimum foraging habitats for polar bears, and polar bear densities in these marine habitats are high all year round. Approximately 350-500 pregnant female polar bears construct their maternity dens on Wrangel and Herald islands every fall, emerging with their cubs in spring. The research is described in terms of goals and objectives, structure, methods, equipment, staff, and implementations.

2007-12-12

319

A motor with superconducting magnetic bearings  

International Nuclear Information System (INIS)

Superconducting bearings may be one of the most promising near term applications of HTSC. For use at liquid nitrogen temperature and below, they offer the advantage of lower energy consumption and higher reliability. Different bearing configurations have been proposed. But in order to substitute for conventional bearings a further increase in the critical current density of the superconductor and improved bearing concepts are necessary. For this it is necessary to take into account the peculiarities of the interaction between permanent magnets and bulk superconductors. As a contribution to this programme we present the model of a motor with superconducting magnetic bearings. (orig.)

1993-01-01

320

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pl...

Hailer, F.; Kutschera, V. E.; Hallstro?m, B. M.; Klassert, D.; Fain, S. R.; Leonard, Jennifer A.; Arnason, U.; Janke, A.

2012-01-01

 
 
 
 
321

Lubrication for high load duplex bearings  

Energy Technology Data Exchange (ETDEWEB)

Three ES and H-compatible lubricants (Environment, Safety and Health) for high load duplex bearing applications were evaluated and compared against trichlorotrifluoroethane (Freon) deposition of low molecular weight polytetrafluoroethylene (PTFE) bearing lubricant extracted from Vydax{trademark}. Vydax is a product manufactured by DuPont consisting of various molecular weights of PTFE suspended in trichlorotrifluoroethane (Freon) which is an ozone-depleting solvent. Bearings with Supercritical CO{sub 2} deposition of PTFE extracted from Vydax AR/IPA, bearings with titanium carbide coated balls, and bearings with diamond-like carbon races and retainers were evaluated. Bearings with Supercritical CO{sub 2} deposition of PTFE from Vydax AR/IPA performed as well as bearings with Freon deposition of PTFE from Freon-based Vydax.

Steinhoff, R.G.

1997-08-01

322

The Nucleation and Propagation of Thrust Ramps: Insights from Quantitative Analysis of Frictional Analog (Sandbox) Models  

Science.gov (United States)

Particle Imaging Velocimetry (PIV) provides a unique opportunity to analyze deformation in sandbox analog models at a scale that allows documentation of movement within and around individual shear structures. We employed PIV analysis to quantify deformation in sandbox experiments designed to simulate the initiation of thrust ramps developed during crustal shortening (i.e., contractional deformation). Our intent was to answer a long-standing question: Do ramps initiate at the tip of a detachment, or do they initiate in the interior of a deforming layer and propagate up-dip and down-dip until they link to the detachment at a location to the hinterland of the detachment's tip line? Most geometric studies of ramp-flat geometries in fold-thrust belts assume that ramps propagate up-dip from the tip of the detachment, and grow only in one direction. Field studies, in contrast, reveal that layer-parallel shortening structures develop to the foreland of the last ramp to form, suggesting that ramps initiate in a thrust sheet that has already undergone displacement above a detachment. Published sandbox models, using color-sand marker layers, support this idea. To test this idea further, we set up a model using a 3 m-long by 0.31-m wide glass-walled sandbox with a rigid backstop. The sand layer was sifted onto a sheet of mylar that could be pulled beneath the rigid backstop. Sand used in our experiments consisted of program called 'PIV LAB' that utilizes an image cross-correlation subroutine to determine displacement fields of the sand particles. Our results demonstrate that: (1) thrust ramps initiate within the deforming stratigraphic layer, not at the detachment tip; (2) the height of the thrust-ramp nucleation point is variable; (3) thrust ramps nucleate to the hinterland of the tip line of the detachment faults; (4) once nucleated, the thrust ramp rapidly propagates up- and down-dip; (5) the linear strain parallel to the ramp decreases exponentially to the ramp tip; (6) once the ramp intersects the detachment, displacement on the detachment to the foreland of the thrust ramp slows as the displacement gets partitioned between the ramp and the detachment; and (7) during progressive deformation, there is cyclic reactivation of out-of-the sequence back-thrusts and fore-thrusts. We conclude that the process of ramp initiation within a layer is similar to the formation of shear fractures by linking of Griffith cracks.

Sen, P.; Haq, S. S.; Marshak, S.

2012-12-01

323

Subduction, platform subsidence, and foreland thrust loading: The late Tertiary development of Taranaki Basin, New Zealand  

Science.gov (United States)

Borehole, seismic, and gravity data are used to investigate deformation of continental lithosphere at a Miocene collisional zone. Deformation is manifested in the three following principal forms: a long wavelength (>500 km) platform subsidence ascribed to mantle convection; flexural deformation on a scale of 100-200 km due to crustal thrusting at the eastern boundary of the Taranaki Basin; and a ductile thickening, evident on the deep seismic section of Taranaki Basin, that occurs on a scale of ˜10 km. Evidence for flexural deformation principally comes from the deep seismic section that shows a 150-km wavelength bending of the Moho down toward the major zone of thrusting within the Taranaki Fault Zone. Paleowater depths, however, provide evidence for an initial early Miocene regional subsidence that is too long in wavelength to be explained by flexure induced from thrust sheet loading. Instead, we propose that this broad "platform subsidence" was driven by loading from a deep source, probably subduction-induced flow in the mantle. By ˜22-19 Ma, 1-2 km of water existed over most of the area now occupied by South Taranaki Basin. By ˜19-17 Ma the water depth in the zone east of the Taranaki Basin, the Taranaki Fault Zone, had been replaced by rock due to submarine thrusting and crustal thickening. This build up of submarine topography in the Taranaki Fault Zone constitutes part of the load (25±8 MPa) that created and maintains South Taranaki Basin. Gravity data place further constraints on loading at the thrust front and point to an additional intracrustal loading, equivalent to 15±7 MPa over a 50-km-wide zone. This intracrustal load is explained as being due to thick-skinned thrusting bringing denser, lower-crustal rocks nearer to the surface in the thrust zone. The complete load on the Taranaki foreland is therefore in three parts; the submarine-topographic load, the intracrustal load, and the loading of infilling sediments.

Holt, W. E.; Stern, T. A.

1994-10-01

324

Detailed Structure of the Large Thrust Slice Zone in the Nankai Trough off Muroto  

Science.gov (United States)

A 3D seismic reflection data set were collected in the Nankai trough off cape Muroto in 1999. Pre-stack time migration has been perfomed on the 3D data. We will present on the detailed structure of the large thrust slice zone revealed from the 3D seismic reflection volume. The Large Thrust Slize Zone (LTSZ) with ˜25km length is located ˜40km landward from the deformation front, where the water depth shallows to 3000m from 4000m. The LTSZ is characterized by the imbricate structure which is also recognized in the frontal thrust zone, and thrust faults developed in the accretionary prism, which suggests that old accretionary prism in the LTSZ has been uplifted by the underplating and thrust faulting. Several faults can be traced in the LTSZ. These faults cut the well stratified imbricate thrust packages. Imbricate package beneath the upper slope area is thicker than that beneath the lower slope area. Strong flat reflectors were imaged beneath the base of the slope. These reflectors are terminated by a low angle fault landward. This setting of flat reflectors and a low angle fault is similar with that at the deformation front off Kumano area. The low angle fault might be a remnant decollement. The flat reflectors are clearly imaged in the southwest half of the 3D box, but not clear in the northeastern part. Low angle landward dipping reflectors (LA-LDRs) are imaged at the depth of 6.5-6.7s beneath the upper slope of whole 3D box. The LA-LDRs accompany with sigmoidal reflection events, which may represent a duplex structure. Some of the thrust faults take off from the landward end of LA-LDRs.

Nakamura, Y.; Bangs, N. L.; Gulick, S. P.; Moore, G. F.; Kuramoto, S.; Shipley, T. H.; Taira, A.

2003-12-01

325

Undulating fins produce off-axis thrust and flow structures.  

Science.gov (United States)

While wake structures of many forms of swimming and flying are well characterized, the wake generated by a freely swimming undulating fin has not yet been analyzed. These elongated fins allow fish to achieve enhanced agility exemplified by the forward, backward and vertical swimming capabilities of knifefish, and also have potential applications in the design of more maneuverable underwater vehicles. We present the flow structure of an undulating robotic fin model using particle image velocimetry to measure fluid velocity fields in the wake. We supplement the experimental robotic work with high-fidelity computational fluid dynamics, simulating the hydrodynamics of both a virtual fish, whose fin kinematics and fin plus body morphology are measured from a freely swimming knifefish, and a virtual rendering of our robot. Our results indicate that a series of linked vortex tubes is shed off the long edge of the fin as the undulatory wave travels lengthwise along the fin. A jet at an oblique angle to the fin is associated with the successive vortex tubes, propelling the fish forward. The vortex structure bears similarity to the linked vortex ring structure trailing the oscillating caudal fin of a carangiform swimmer, though the vortex rings are distorted because of the undulatory kinematics of the elongated fin. PMID:24072799

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

2014-01-15

326

Hunting Bears with a Microscope  

Science.gov (United States)

In this online activity, students use lichens and tardigrades (water bears) to investigate their use as bioindicators of key air pollutants. When lichens are exposed to some kinds of air pollutants, especially to sulfur dioxide, the lichens are injured and die. The lichen coverage in a specified area should be a good indicator of the level of air quality. The diversity of the tardigrade species on the lichens will be used to develop another level for bioindication of air quality. Sections of this activity include: introduction, sulfur dioxide and lichens, sampling procedure for lichen coverage, tardigrade sampling, sampling procedure for tardigrades, calculating diversity using the Simpson Diversity Index, interpretation of results, and references.

Case, Steve

2010-02-10

327

The seismic cycle at subduction thrusts: a parameter study  

Science.gov (United States)

In this study, we model long-term seismic cycles at subduction thrusts. The understanding of this process in nature is restricted due to three interrelated problems: (i) the limited spatiotemporal availability of direct observations of the (ii) mechanically and geometrically variable subduction zones, which (iii) are each at different stages of the seismic cycle, without completing one while direct observations took place. Numerical modeling has the potential to overcome these problems and, hence, contribute to improve long-term hazard assessment in subduction zones. We use the 2D continuum visco-elasto-plastic, seismo-mechanical numerical model of a laboratory-scaled subduction zone, consisting of a gelatin wedge underthrusted by a rigid plate. In a frictional boundary layer above the rigid plate, which is governed by strongly rate-dependent friction, the velocity-weakening seismogenic zone (SeZ) is surrounded at its up- and downdip limits by velocity-strengthening areas. This numerical modeling approach to model seismic cycles was validated (van Dinther et. al., 2013) against an innovated laboratory model (Corbi et. al., 2013). This follow-up parameter study investigates the role of subduction velocity and geometrical properties of the SeZ on the recurrence behavior and source properties of spontaneously evolving events with complex rupture patterns. Results are compared to natural observations and to laboratory models performed under comparable experimental conditions. In the numerical models, events nucleate predominantly near the limits of the SeZ. In a wider and shallower SeZ, a preference exists for nucleation near the downdip limit. The recurrence interval between the characteristic large events of each model setup decreases non-linearly with subduction velocity. Both the maximum source properties and the recurrence interval between the characteristic large events increases with the SeZ width. In contrast, the subduction velocity has only a minor impact on the maximum source properties. Especially in a SeZ close to the trench, we observe accelerations in the velocity-strengthening material for ruptures reaching the trench, leading to large peak slip velocities and coseismic slip. Detailed studies of specific models provide additional insights into the existing rupture styles. Sub-critical ruptures, and decaying, growing as well as back-propagating pulses of different sizes change the stress distribution inside the SeZ during a seismic cycle. Thereby, these smaller events influence the nucleation location and propagation of subsequent ruptures. When the stress in the SeZ reaches a critical state, the characteristic large events develop as crack-like ruptures or ruptures in the transitional regime between pulses and cracks. These kind of events lead to a significant stress drop across the entire SeZ and, hence, are followed by a period of relative quiescence and again smaller events. The wider the SeZ, the larger are the number and range of smaller events, which occur between the recurring characteristic large events.

Herrendoerfer, R.; van Dinther, Y.; Gerya, T.; Dalguer, L. A.; Corbi, F.; Funiciello, F.

2013-12-01

328

??????–????????????????—????????? Evolution and Later Reformation of Early-Middle Jurassic Coal-Bearing Basins in Western Mongolia—A Case Study from the Shinejinst Basin  

Directory of Open Access Journals (Sweden)

Full Text Available ?????????????????????????????–??????????????????????????????????????????????????????–?????????????????????????–???????????????–??????????????????????????????????(??????????????????????????????????????????????????????????????????????–???????????????????????????????????????????????–?????????????????????????????????????????????????????????????Owing to variation of the basement structures, syn-orogenic stress fields and regional tectonic evolution, the Early-Middle Jurassic coal-bearing basins in western Mongoliashow different geometric and kinematic features from the simultaneous molasse basins in easternMongolia. The west segment of the Mongolia-Okhotsk suture is a NW- striking transfer zone, which constraints two transpressional fracture belts developing in western Mongolia. The tran- spressional fracture consists of the oblique thrust with NWW- to nearly E-W-striking, and the NW-orientated oblique thrust-strike slipping fault. The front fault of the oblique thrust controls a coal-forming basin in its lower plate. The ba- sin-controlling fault thrusts north(eastwards, with the basin dynamics resulting from a northward push-compression caused by closure of Tethyan ocean in the end of Early Jurassic in western China and followed continent-continent col- lision. The evolution of the Shinejinst Basin can be divided into three stages, which experiences four episodes of refor- mation after its reversion. The coal-search direction for the Lower-Middle Jurassic large coal fields in western Mongo- lia should be a kind of the South Sub-Basin of Shinejinst Basin, which could be indicated by three characters: 1 the basin-controlling faults being NWW- to nearly E-W-striking oblique thrust as well as NE-striking sinistral shearing fault, 2 to be situated at upper side of normal fault in Early Cretaceous extension, and 3 to be located along the piedmont belt of thrust or foothill of range in the Cenozoic uplifting.

???

2013-08-01

329

Engineering Research and Development and Technology thrust area report FY92  

Energy Technology Data Exchange (ETDEWEB)

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.

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

1993-03-01

330

High-speed engine/component performance assessment using exergy and thrust-based methods  

Science.gov (United States)

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

Riggins, D. W.

1996-01-01

331

Hollow Cathode and Low-Thrust Extraction Grid Analysis for a Miniature Ion Thruster  

International Nuclear Information System (INIS)

Miniature ion thrusters are well suited for future space missions that require high efficiency, precision thrust, and low contamination in the mN to sub-mN range. JPL's miniature xenon Ion (MiXI) thruster has demonstrated an efficient discharge and ion extraction grid assembly using filament cathodes and the internal conduction (IC) cathode. JPL is currently preparing to incorporate a miniature hollow cathode for the MiXI discharge. Computational analyses anticipate that an axially upstream hollow cathode location provides the most favorable performance and beam profile; however, the hot surfaces of the hollow cathode must be sufficiently downstream to avoid demagnetization of the cathode magnet at the back of the chamber, which can significantly reduce discharge performance. MiXI's ion extraction grids are designed to provide >3 mN of thrust; however, previous to this effort, the low-thrust characteristics had not been investigated. Experimental results obtained with the MiXI-II thruster (a near replica or the original MiXI thruster) show that sparse average discharge plasma densities of 5 x 1015 5x1016 m-3 allow the use of very low beamlet focusing extraction voltages of only 250 500 V, thus providing thrust levels as low as 0.03 mN for focused beamlet conditions. Consequently, the thrust range thus far demonstrated by MiXI in this and other tests is 0.03 1.54 mN.

2009-01-01

332

Structure of the Chamba nappe and position of the Main Central Thrust in Kashmir Himalaya  

Science.gov (United States)

The Chamba nappe, composed of an approximately 8 km thick sequence of Late Precambrian to Jurassic age rocks is located between the Higher Himalaya Crystallines (HHC) and the Lesser Himalayan (LH) formations of Panjal Imbricate Zone (PIZ) in the Kashmir Himalaya. To the south, the Panjal Thrust, demarcating the base, brings the Chamba nappe rocks over the Panjal Imbricate Zone. To the north, the Chamba nappe rocks lie over the metamorphic HHC along the south dipping Chenab Normal Fault (CNB). A pervasive stretching lineation defined by a mineral lineation, stretched pebbles and felspar phenocrysts plunges NE-NNE and occurs on the foliation/cleavage surface. This lineation is related to southward displacement of the Chamba nappe. The Chamba nappe is folded by regional scale fold, viz. the Chamba, Tandi and Bharmor synclines and the Tisa anticline. These NW-SE trending folds structures were developed synchronously with southward thrusting of the Chamba nappe. The Chamba nappe results from southwestward sliding of cover rocks from their basement (HHC) due to topographic uplift. The Main Central Thrust (MCT) in Kashmir Himalaya is different from that of the Kumaun and Nepal Himalaya. The MCT (Vaikrita Thrust) does not extend west of the Beas river, but it is exposed in the Rampur Window and the Kishtwar Window separating the HHC from the underlying LH rocks. Southward propagation of the MCT from the window zone, up-cutting the overlying HHC, is transferred to the Panjal Thrust which transports the Chamba nappe to the south over the Lesser Himalayan formations.

Thakur, V. C.

1998-04-01

333

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 pro...

Lupi, M.; Miller, S. A.

2013-01-01

334

Model Of Bearing With Hydrostatic Damper  

Science.gov (United States)

Improved mathematical model of rotational and vibrational dynamics of bearing package in turbopump incorporates effects of hydrostatic damper. Part of larger finite-element model representing rotational and vibrational dynamics of rotor and housing of pump. Includes representations of deadband and nonlinear stiffness and damping of ball bearings, nonlinear stiffness and damping of hydrostatic film, and stiffness of bearing support. Enables incorporation of effects of hydrostatic damper into overall rotor-dynamic mathematical model without addition of mathematical submodel of major substructure.

Goggin, David G.

1991-01-01

335

Evaluation of Journal Bearings in Manual Transmissions  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis work is an evaluation of journal bearings in manual transmissions in automobiles. Today both journal- and needle bearings can be positioned into the gearboxes and in order to reduce the power loss developed by friction when a relative angular velocity arises, the right type of bearing must be chosen. In order to succeed, this work is aimed to develop a Matlab simulation model, which should be used as a tool in the design process of manual transmissions. The program development is ...

Vidar, Joachim; Mellstedt, Jonas

2009-01-01

336

Nonlinear Dynamic Response of Compliant Journal Bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper investigates the dynamic response of the compliant tilting pad journal bearings subjected to synchronous excitation. Bearing compliance is affected by the properties of pad liner and pad support geometry. Different unbalance eccentricities are considered. It is shown that bearing dynamic response is non-linear. Journal orbit complexity increases with pad compliance though the orbit amplitudes are marginally affected at low loads. At high loads, the journal is forced to operate outs...

Cha M.; Glavatskih S.

2012-01-01

337

Electromechanical properties of radial active magnetic bearings  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Nonideal properties of the electromagnetic actuators in radial active magnetic bearings are studied. The two dimensional nonlinear stationary finite element method is used to determine the linearised parameters of a radial active magnetic bearing. The method is verified on two test machines. The accuracy is 10-15 % in the magnetic saturation region. The effect of magnetic saturation on the bearing dynamics is studied based on the root locus diagrams of the closed loop system. These diagrams s...

Antila, Matti

1998-01-01

338

Single axis controlled attraction type magnetic bearing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents a new type of magnetic bearing with active control only in axial direction. The bearing uses two pairs of permanent magnets working in attraction mode to restrict the radial motion and a control system composed of two electromagnets, a gap sensor and a controller to keep the axis in a fixed axial position. The principle, the dynamic model for axial motion and the control system for this bearing are presented. Finally, by experiments conducted in a prototype, the effectiven...

Horikawa, O.; Da Silva, I.

2002-01-01

339

Magnetic bearing as switched reluctance motor  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The goal of this work was to research the similarities between active magnetic bearings and switched reluctance motor and particularly research the chances for converting magnetic bearing into switched reluctance motor. In addition, ways to cope with the widely reported problems the motor type has were studied. The test environment consisted of test rig, previously used for testing control methods for magnetic bearing. In addition to this, MATLAB Simulink simulation models were built to he...

Halmeaho, Teemu

2012-01-01

340

Technical Development Path for Foil Gas Bearings  

Science.gov (United States)

Foil gas bearings are in widespread commercial use in air cycle machines, turbocompressors and microturbine generators and are emerging in more challenging applications such as turbochargers, auxiliary power units and propulsion gas turbines. Though not well known, foil bearing technology is well over fifty years old. Recent technological developments indicate that their full potential has yet to be realized. This paper investigates the key technological developments that have characterized foil bearing advances. It is expected that a better understanding of foil gas bearing development path will aid in future development and progress towards more advanced applications.

DellaCorte, Christopher

2008-01-01

 
 
 
 
341

Permanent Magnetic Bearing for Spacecraft Applications  

Science.gov (United States)

A permanent, totally passive magnetic bearing rig was designed, constructed, and tested. The suspension of the rotor was provided by two sets of radial permanent magnetic bearings operating in the repulsive mode. The axial support was provided by jewel bearings on both ends of the rotor. The rig was successfully operated to speeds of 5500 rpm using an air impeller. Radial and axial stiffnesses of the permanent magnetic bearings were experimentally measured and then compared to finite element results. The natural damping of the rotor was measured and a damping coefficient was calculated.

Morales, Winfredo; Fusaro, Robert; Kascak, Albert

2008-01-01

342

The Effect of High Concentration Guanidinium Azo-Tetrazolate on Thrust and Specific Impulse of a Hybrid Rocket  

Science.gov (United States)

A thrust and impulse study of the hybrid rocket fuel additive, Guanidinium Azo-Tetrazolate (GAT), was conducted at the University of Arkansas at Little Rock (UALR) Hybrid Rocket Facility. GAT is an organic salt with a high percentage of nitrogen. GAT was mixed with the standard hybrid rocket fuel, Hydroxyl-Terminated Polybutadiene (HTPB), in concentrations of 15% and 25%, by mass. The fuel grains with the GAT additive were fired for 4 second runs with oxygen flows of 0.04, 0.06, 0.08, and 0.10 lbm/sec. For each run, average thrust, standard deviation of thrust, total impulse, and specific impulse were measured. Average thrust, standard deviation of thrust, specific impulse and total impulse vs. oxygen flow were plotted. Similar data was collected for plain HTPB/PAPI fuels for comparison. GAT is found to increase the thrust output when added to the standard hybrid rocket fuel, HTPB. 25% GAT fuel produced approximately the same thrust as the 15% GAT fuel. Specific impulse was slightly lower with both 15% and 25% GAT fuels. Standard Deviation of thrust was used as a crude measure of amplitude of oscillations during combustion. GAT-added fuels showed a limited decrease in thrust oscillation amplitude.

Tilahun, Dagim; Wright, A.; Foley, P.; Reason, M.

2001-04-01

343

On the problem of optimal control of the thrust value of the electric propulsion rocket with solar energy source  

Science.gov (United States)

Under consideration is the optimal control problem on a spacecraft motion in Newtonian central gravity field. With the use of the mathematical model of electrojet propulsion device (EPD) with solar energy source, proposed earlier in paper [1], the dependence of the EPD working substance choice on both the duration of the given dynamic maneuver and the propellant expenditures for its fulfillment is investigated. The efficiency evaluation is carrying out of optimal control of variable valued thrust as well as that for relay mode thrust and relay mode thrust with optimal fixed thrust value.

Kiforenko, Boris N.; Vasil'ev, Igor Yu.; Tkachenko, Yaroslav V.

2013-08-01

344

OFFICE OF SCIENCE AND TECHNOLOGY AND INTERNATIONAL, NATURAL BARRIERS THRUST OVERVIEW  

Energy Technology Data Exchange (ETDEWEB)

The Natural Barriers Thrust supports scientific studies of the natural system at the proposed repository site of Yucca Mountain. It stresses the realistic representation of the natural system with respect to processes and parameters, by means of laboratory, field, and modeling studies. It has the objectives to demonstrate that the natural barriers can make large contributions to repository performance, supporting the multiple-barrier concept for geological disposal of high-level radioactive waste; and to reduce the overall cost of repository development by elimination of unnecessary engineered components, given the demonstrated natural barriers performance. In this overview we enumerate the research projects within the Natural Barriers Thrust grouped under five elements: (1) Drift Seepage, (2) In-drift Environment, (3) Drift Shadow, (4) Unsaturated Zone Flow and Transport, and (5) Saturated Zone Flow and Transport. The long-term strategic plan of the Natural Barriers Thrust and some key results are also briefly described.

B. Bodvarsson; Y. Tsang

2006-02-21

345

Thrust Vectoring of a Continuous Rotating Detonation Engine by Changing the Local Injection Pressure  

Science.gov (United States)

The thrust vectoring ability of a continuous rotating detonation engine is numerically investigated, which is realized via increasing local injection stagnation pressure of half of the simulation domain compared to the other half. Under the homogeneous injection condition, both the flow-field structure and the detonation wave propagation process are analyzed. Due to the same injection condition along the inlet boundary, the outlines of fresh gas zones at different moments are similar to each other. The main flow-field features under thrust vectoring cases are similar to that under the baseline condition. However, due to the heterogeneous injection system, both the height of the fresh gas zone and the pressure value of the fresh gas in the high injection pressure zone are larger than that in the low injection pressure zone. Thus the average pressure in half of the engine is larger than that in the other half and the thrust vectoring adjustment is realized.

Liu, Shi-Jie; Lin, Zhi-Yong; Sun, Ming-Bo; Liu, Wei-Dong

2011-09-01

346

A computer program for wing subsonic aerodynamic performance estimates including attainable thrust and vortex lift effects  

Science.gov (United States)

Numerical methods incorporated into a computer program to provide estimates of the subsonic aerodynamic performance of twisted and cambered wings of arbitrary planform with attainable thrust and vortex lift considerations are described. The computational system is based on a linearized theory lifting surface solution which provides a spanwise distribution of theoretical leading edge thrust in addition to the surface distribution of perturbation velocities. The approach used relies on a solution by iteration. The method also features a superposition of independent solutions for a cambered and twisted wing and a flat wing of the same planform to provide, at little additional expense, results for a large number of angles of attack or lift coefficients. A previously developed method is employed to assess the portion of the theoretical thrust actually attainable and the portion that is felt as a vortex normal force.

Carlson, H. W.; Walkley, K. B.

1982-01-01

347

R+D works for the further development of high temperature reactors. (1) Captive bearing experiments for active magnetic bearings. (2) Captive bearing test for HTR blowers  

International Nuclear Information System (INIS)

When using active magnetic bearings as blower shaft bearings, blower motors and bearings must be protected against mechanical damage in case of faults (example: total electrical supply failure due to the supply cables breaking). So-called captive bearings are provided, in order to be able to shut the blowers down safely in such faults. These captive bearings are roller bearings which are additionally fitted in the area of the blower shaft bearings, to prevent mechanical contact between the blower rotor and stator. As there was little experience available for the given boundary conditions, such as - speed, - acceleration, - bearing load, - bearing dimensions, - ambient conditions, appropriate development and tests had to be carried out. It was important to determine suitable captive bearings and the necessary ambient conditions, which will make it possible to support the failures of the magnetic bearings to be expected in 40 years' operation of the reactor without damage and to meet the requirements of the captive bearings. (orig./GL)

1991-01-01

348

Nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage.  

Science.gov (United States)

Recent studies have shown that the polar bear matriline (mitochondrial DNA) evolved from a brown bear lineage since the late Pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. Here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. Bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle Pleistocene, about 600 (338 to 934) thousand years ago. This provides more time for polar bear evolution and confirms previous suggestions that polar bears carry introgressed brown bear mitochondrial DNA due to past hybridization. Our results highlight that multilocus genomic analyses are crucial for an accurate understanding of evolutionary history. PMID:22517859

Hailer, Frank; Kutschera, Verena E; Hallström, Björn M; Klassert, Denise; Fain, Steven R; Leonard, Jennifer A; Arnason, Ulfur; Janke, Axel

2012-04-20

349

Constant-thrust glideslope guidance algorithm for time-fixed rendezvous in real halo orbit  

Science.gov (United States)

This paper presents a fixed-time glideslope guidance algorithm that is capable of guiding the spacecraft approaching a target vehicle on a quasi-periodic halo orbit in real Earth-Moon system. To guarantee the flight time is fixed, a novel strategy for designing the parameters of the algorithm is given. Based on the numerical solution of the linearized relative dynamics of the Restricted Three-Body Problem (expressed in inertial coordinates with a time-variant nature), the proposed algorithm breaks down the whole rendezvous trajectory into several arcs. For each arc, a two-impulse transfer is employed to obtain the velocity increment (delta-v) at the joint between arcs. Here we respect the fact that instantaneous delta-v cannot be implemented by any real engine, since the thrust magnitude is always finite. To diminish its effect on the control, a thrust duration as well as a thrust direction are translated from the delta-v in the context of a constant thrust engine (the most robust type in real applications). Furthermore, the ignition and cutoff delays of the thruster are considered as well. With this high-fidelity thrust model, the relative state is then propagated to the next arc by numerical integration using a complete Solar System model. In the end, final corrective control is applied to insure the rendezvous velocity accuracy. To fully validate the proposed guidance algorithm, Monte Carlo simulation is done by incorporating the navigational error and the thrust direction error. Results show that our algorithm can effectively maintain control over the time-fixed rendezvous transfer, with satisfactory final position and velocity accuracies for the near-range guided phase.

Lian, Yijun; Meng, Yunhe; Tang, Guojian; Liu, Luhua

2012-10-01

350

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

Science.gov (United States)

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.

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

1985-02-01

351

Tectonic development of Laramide thrusts and basins in southern US Rocky Mountains  

Energy Technology Data Exchange (ETDEWEB)

To elucidate the tectonic nature of the Laramide faults and basins and their role in controlling the development of late Cenozoic extensional structures, the authors compiled a tectonic map and constructed a series of E-W cross-sections between latitude 41[degree]N and latitude 32[degree]N along the Rockies. The tectonic map and balanced cross-sections show that the northern part of the southern Rockies is characterized by a W-directed thrust system and the southern part by an E-directed thrust system. The W- and E-directed systems overlap between 39[degree]N and 38[degree]N. On the surface, the transfer of shortening from the W-directed to the E-directed thrust system was accomplished by variation of displacements along strike of the two thrust systems. The authors hypothesize that the slip transfer at depth was accommodated along a commonly shared sub-horizontal detachment in the plastically deformed mid-crust, a situation similar to the recently documented basement-involved thrust systems in the South American Andes on the basis of focal-mechanism studies. The balanced cross-sections show that no systematic increase in shortening southward along strike of the southern Rockies can be detected within the resolution of the available surface and subsurface data. Dickinson and others (1988) classified three types of Laramide basins in the central Rockies on the basis of their structural settings: perimeter, ponded, and axial. Much debate has been centered on the origin of the axial basins that are characteristic of the southern Rockies. It is not clear whether they are the result of compressional tectonics, transpressional tectonics, or the superposition of the two in both time and space. An evolutionary model systematically accounts for the development of thrusts and basins during the Laramide orogeny and their influence on the development of younger normal faults and extensional basins during the late Cenozoic.

Yin, A.; Ingersoll, R.V. (Univ. of California, Los Angeles, CA (United States). Dept. of Earth and Space Sciences)

1993-04-01

352

Structure of the Coalinga area and thrust origin of the earthquake  

Energy Technology Data Exchange (ETDEWEB)

The 1983 Coalinga main shock occurred at the eastern margin of the Coast Ranges beneath Coalinga anticline, which forms the northwest segment in a 100-km-long zone of young anticlines about 35 km northeast of the San Andreas fault. Northeast-directed thrusts (here named the Coalinga thrust zone) terminated beneath the anticline at a depth of about 10 km in a series of upward-splaying reverse faults, above which the anticline has grown in the past 2 Ma. A distinct flattening near the center of the northeastern limb of the fold separates it into upper and lower tiers, which are related to separate reverse-fault splays below. The main shock appears to have occurred at the base of a reverse-fault splay beneath the upper tier of the fold and produced a focal mechanism with a gently southwest-dipping focal plane that strikes parallel to the fold axis. Rupture propagated bilaterally back down the thrust and up the reverse fault. Thrusting of the type responsible for the growth of Coalinga anticline probably extends the length of the Coalinga-Kettleman Hills-Lost Hills anticlinal trend, with tear faults at the echelon steps in the trend. The earthquake occurred east of the north-trending Pleasant Valley cross-structure. The structural setting for this recent thrusting east of the San Andreas fault was established in the Mesozoic under a different tectonic regime. The basement shallows northeastward from its 15-km depth beneath the Diablo Range, first at 15{degree}-20{degree} beneath the west side of the San Joaquin Valley and then more gently. This shallowing of basement probably limited northeastward penetration of the Franciscan wedge and seems to be limiting the more recent thrusting as well.

Zoback, M.D. (Stanford Univ., CA (USA)); Wentworth, C.M.

1990-01-01

353

Modeling and simulation of porous journal bearings in multibody systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A specific cost-efficient type of plain journal bearing is the porous journal bearing, which possesses a pervious bush that serves as a lubricant reservoir. The current work is concerned with modeling porous journal bearings in multibody systems, for which dynamical models are needed to investigate the bearing’s behavior. Such porous journal bearing models as well as models of elementary rotor-bearing systems including these, were developed and investigated during the course for this work.

Buuren, Sietze

2013-01-01

354

BEAR electrostatic analyzer: Flight results  

Energy Technology Data Exchange (ETDEWEB)

The Electrostatic Analyzer (ESA) measured the intensity of charged particles returning to the BEAR payload during flight on 13 July 1989. These particles form part or all of the current that returns to the payload to neutralize the charge ejected with the beam. By measuring the return flux with high time resolution, we can study the physics of charging processes. When the neutralizer was off, the payload emitted 10 mA negative and charged to several hundred volts with a maximum of{approximately}800V. With the neutralizer on (normal configuration) the payload emitted {approximately} 1mA negative and received electrons with energies up to a few hundred volts in some attitudes. This suggests charging to a few hundred volts. The charging rate of the payload is consistent with the rocket body capacitance with respect to a vacuum. 1 ref., 14 figs.

Anerson, H.R.; Potter, D.W.; Morse, D.L.; Olson, J.R.; Johnson, J.L. (Science Applications International Corp., Bellevue, WA (USA)); Pongratz, M. (Los Alamos National Lab., NM (USA))

1990-01-03

355

Gearbox Reliability Collaborative Bearing Calibration  

Energy Technology Data Exchange (ETDEWEB)

NREL has initiated the Gearbox Reliability Collaborative (GRC) to investigate the root cause of the low wind turbine gearbox reliability. The GRC follows a multi-pronged approach based on a collaborative of manufacturers, owners, researchers and consultants. The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database. At the core of the project are two 750kW gearboxes that have been redesigned and rebuilt so that they are representative of the multi-megawatt gearbox topology currently used in the industry. These gearboxes are heavily instrumented and are tested in the field and on the dynamometer. This report discusses the bearing calibrations of the gearboxes.

van Dam, J.

2011-10-01

356

Bifurcation Onset Delay in Magnetic Bearing Systems with Auxiliary Bearing and Time Varying Stiffness  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Auxiliary bearings are used in magnetic bearing systemsto protect bearings from damage. These bearings are in contact with rotor temporarily. This contact associated with intermittent contact forces which change the system dynamic behavior. These include vibration instability and thermal stresses. The system is simulated to clarify the role of two different control methods in synchronous and asynchronous responses.This is carried out using linear PD controller and time varying stiffn...

Ghazavi, M. R.; Sun, Q.

2012-01-01

357

Axial-thrust responses due to a gas turbine's rotor blade distortions  

Science.gov (United States)

The axial thrust imposed on the shaft of a gas turbine depends upon its rotor blade inlet inclination to the turbine's axial direction: this inclination can change due to the distortions resulting from fouling, aging, tip rubbing, erosion, thermal-fatigue cracks, and corrosion. Relevant influential parameters for an operational gas turbine were measured. Theoretical predictions for the behavior of the same turbine were obtained from computer simulations. The results of both measurements and theoretical predictions were compared and showed qualitative correspondence. The rotor blade profile distortions result in significant increases in the axial thrust on the compressor, which adversely affects the gas turbine's thermodynamic performance, reliability, and operational life.

Lebele-Alawa, B. T.

2010-11-01

358

Thrust and Flow Prediction in Gas Turbine Engine Indoor Sea-Level Test Cell Facilities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The principal aim of this research was to provide a detailed understanding of the performance of gas turbine engines inside indoor sea-level test beds. In particular the evaluation of both thrust correction factors and the estimation of the mass flow entering the test cell were at the core of the research. The project has been fully sponsored by Rolls-Royce pIc. Initially, their principal objective was to assess the relevance and accuracy of CFD when applied to thrust measur...

Gullia, Alessandro

2006-01-01

359

Dimension-optimizing design method for annular-type cooling channel of thrust chamber  

Science.gov (United States)

The new-generation liquid oxygen/hydrocarbon propellant liquid fuel rocket engine will use a high-pressure combustion chamber arrangement. In this case, cooling the thrust chamber becomes a key technical problem. The article presents a design scheme for the geometric-dimension optimization of annular-type regenerative cooling channels. The aim of the optimization is minimum pressure losses as coolant passes through the cooling channel. As shown in typical computations and experiments, application of this optimizing design method can reduce 50 percent of pressure losses. In other words, the optimization design is advantageous in solving the cooling problem in high-pressure thrust chambers.

Chen, Jie

1995-05-01

360

Orbital Maneuvers Using Low Thrust to Place a Satellite in a Constellation  

Directory of Open Access Journals (Sweden)

Full Text Available This paper considers the problem of low thrust suboptimal maneuvers to insert a satellite in a constellation. It is assumed that a satellite constellation is given with all the Keplerian elements of the satellite members having known values. Then, it is necessary to maneuver a new satellite from a parking orbit to its position in the constellation. The control available to perform this maneuver is the application of a low thrust to the satellite and the objective is to perform this maneuver with minimum fuel consumption.

Helio Koiti Kuga

2007-01-01

 
 
 
 
361

3-D acquisition realities and processing strategies in mountainous thrust areas  

Energy Technology Data Exchange (ETDEWEB)

The inherent structural complexity of thrust plays makes them ideal candidates for 3-D seismic imaging. However, there are many practical constraints placed on the acquisition of 3-D data in the mountainous terrains typically associated with thrust regimes. Financial considerations ca result in tradeoffs between a desired acquisition geometry and that which is practical. Topographic relief can also impose irregular geometries and shortened receiver arrays. Such factors create challenges to the formation of a valid 3-D seismic image. Therefore, the realities of acquiring data in mountainous areas must be coupled to the appropriate processing strategies to yield an optimal result. (author). 7 refs., 5 figs

MacKay, Scott; Wright, Stuart; Gaiser, James; Jackson, Alex [Western Geophysical, Englewood, CO (United States); Beasley, Craig; Wisecup, R. Daniel [Western Geophysical, TX (United States)

1995-12-31

362

Single thrust period missions to Uranus for unmanned nuclear-electric propulsion systems  

Science.gov (United States)

The effects of trip time, propulsion time, and specific powerplant mass are studied for optimized unmanned probe spacecraft on missions to Uranus with nuclear-electric propulsion systems. Electric propulsion is confined to a single thrust period at the beginning of each mission. Mission profiles include both high-thrust and electric-propulsion Earth-departure modes for planet flyby and orbital capture. Effects of propulsion time and propulsion system parameters are evaluated, and typical design features of the nuclear-electric spacecraft are outlined. Payload capability comparisons are made with systems employing ballistic transfer and solar-electric propulsion.

Zola, C. L.

1973-01-01

363

Direct measurement of the impulse in a magnetic thrust chamber system for laser fusion rocket  

International Nuclear Information System (INIS)

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

2011-08-15

364

Direct measurement of the impulse in a magnetic thrust chamber system for laser fusion rocket  

Energy Technology Data Exchange (ETDEWEB)

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

Maeno, Akihiro; Yamamoto, Naoji; Nakashima, Hideki [Interdisciplinary Graduate School of Engineering Science, Kyushu University, 6-1 Kasuga-kouen, Kasuga, Fukuoka 816-8580 (Japan); Fujioka, Shinsuke; Johzaki, Tomoyuki [Institute of Laser Engineering, Osaka University, Suita, Osaka 565-087 (Japan); Mori, Yoshitaka [Graduate School for the Creation of New Photonics Industries, Hamamatsu, Shizuoka 431-1202 (Japan); Sunahara, Atsushi [Institute for Laser Technology, Suita, Osaka 565-087 (Japan)

2011-08-15

365

A reevaluation of the age of the Vincent-Chocolate Mountains thrust system, southern California  

Energy Technology Data Exchange (ETDEWEB)

The Vincent-Chocolate Mountains (VCM) thrust superposes Mesozoic arc plutons and associated Precambrian country rock above subduction-related Pelona-Orocopia schist. The thrust is disrupted in many areas by postmetamorphic deformation, but appears to be intact in the San Gabriel Mountains. Two Rb-Sr mineral-isochron ages from Pelona Schist and mylonite in the San Gabriel Mountains led Ehlig (1981) to conclude that the original thrusting event occurred at c. 60 Ma. However, biotite K-Ar ages determined by Miller and Morton (1980) for upper plate in the same area caused Dillon (1986) to reach a different conclusion. The biotite ages range mainly from 74--60 Ma and increase structurally upward from the VCM thrust. Dillon (1986) inferred that the age gradient was due to uplift and cooling of the upper plate during underthrusting of Pelona Schist. This would indicate that the VCM thrust was at least 74 Ma in age. An alternative to the interpretation of Dillon (1986) is that the biotite age gradient largely predates the VCM thrust. Upward heat flow, leading to older ages at higher structural levels, could have resulted from either static cooling of Cretaceous plutons or uplift and erosion induced by crustal thickening during possible west-directed intra-arc thrusting at c. 88--78 Ma (May and Walker, 1989). Subsequent underthrusting of Pelona Schist would establish a cold lower boundary to the crust and cause the closure of isotopic systems in the base of the upper plate. A 60 Ma time of thrusting is also suggested by two amphibole [sup 40]Ar/[sup 39]Ar ages from the Pelona Schist of the San Gabriel Mountains. Peak metamorphic temperature in this area was below 480 C and amphibole ages should thus indicate time of crystallization rather than subsequent cooling. Four phengite [sup 40]Ar/[sup 39]Ar ages of 55--61 Ma from Pelona Schist and mylonite indicate rapid cooling from peak metamorphic temperatures, consistent with subduction refrigeration.

Jacobsen, C.E. (Iowa State Univ., Ames, IA (United States). Dept. of Geological and Atmospheric Sciences); Barth, A.P. (Indiana Univ.--Purdue Univ., Indianapolis, IN (United States). Dept. of Geology)

1993-04-01

366

Characterisation of Materials Used in Flex Bearings of Large Solid Rocket Motors  

Directory of Open Access Journals (Sweden)

Full Text Available Solid rocket motors are propulsion devices for both satellite launchers and missiles, which require guidance and steering to fly along a programmed trajectory and to compensate for flight disturbances. A typical solid rocket motor consists of motor case, solid propellant grain, motor insulation, igniter and nozzle. In most solid rocket motors, thrust vector control (TVC is required. One of the most efficient methods of TVC is by flex nozzle system. The flex nozzle consists of a flexible bearing made of an elastomeric material alternating with reinforcement rings of metallic or composite material. The material characterisation of AFNOR 15CDV6 steel and the natural rubber-based elastomer developed for use in flex nozzle are discussed. This includes testing, modelling of the material, selection of a material model suitable for analysis, and the validation of material model.

CH.V. Ram Mohan

2011-05-01

367

The Dauki Thrust Fault and the Shillong Anticline: An incipient plate boundary in NE India?  

Science.gov (United States)

The Shillong Massif is a regional contractional structure developing across the Assam sliver of the Indian plate near the Eastern Syntaxis between the Himalaya and Burma arcs. Faulting associated with the Shillong Massif is a major source of earthquake hazard. The massif is a composite basement-cored asymmetric anticline and is 100km wide, >350km long and 1.8km high. The high relief southern limb preserves a Cretaceous-Paleocene passive margin sequence despite extreme rainfall while the gentler northern limb is devoid of sedimentary cover. This asymmetry suggests southward growth of the structure. The Dauki fault along the south limb builds this relief. From the south-verging structure, we infer a regional deeply-rooted north-dipping blind thrust fault. It strikes E-W and obliquely intersects the NE-SW margin of India, thus displaying three segments: Western, within continental India; Central, along the former passive margin; and Eastern, overridden by the west-verging Burma accretion system. We present findings from recent geologic fieldwork on the western and central segments. The broadly warped erosional surface of the massif defines a single anticline in the central segment, east of the intersection with the hinge zone of the continental margin buried by the Ganges-Brahmaputra Delta. The south limb of the anticline forms a steep topographic front, but is even steeper structurally as defined by the Cretaceous-Eocene cover. Below it, Sylhet Trap Basalts intrude and cover Precambrian basement. Dikes, presumably parallel to the rifted margin, are also parallel to the front, suggesting thrust reactivation of rift-related faults. Less competent Neogene clastics are preserved only near the base of the mountain front. Drag folds in these rocks suggest north-vergence and a roof thrust above a blind thrust wedge floored by the Dauki thrust fault. West of the hinge zone, the contractional structure penetrates the Indian continent and bifurcates. After branching into the Dapsi Fault, the Dauki Fault continues westward as the erosion-deposition boundary combined with a belt of N-S shortening. The Dapsi thrust fault strikes WNW across the Shillong massif and dips NNE. It is mostly blind below a topographically expressed fold involving basement and passive-margin cover. Recent fieldwork has shown that the fault is better exposed in the west, where eventually Archean basement juxtaposes folded and steeply dipping fluvial sediment. Both Dauki and Dapsi faults probably continue beyond the Brahmaputra River, where extreme fluvial processes mask them. The area between the two faults is a gentle southward monocline with little or no shortening. Thus uplift of this area stems from slip on the Dauki thrust fault, not from pervasive shortening. The Burma foldbelt overrides the Shillong Plateau and is warped but continuous across the eastern segment of the Dauki fault. The Haflong-Naga thrust front north of the Dauki merges with the fold-thrust belt in the Sylhet basin to the south, despite >150km of differential advance due to much greater advance of the accretionary prism in the basin. Where the Dauki and Haflong-Naga thrusts cross, the thrust fronts are nearly parallel and opposite vergence. We trace a Dauki-related topographic front eastward across the Burma Range. This and other evidence suggest that the Dauki Fault continues below the foldbelt.

Ferguson, E. K.; Seeber, L.; Steckler, M. S.; Akhter, S. H.; Mondal, D.; Lenhart, A.

2012-12-01

368

Self-adjusting magnetic bearing systems  

Energy Technology Data Exchange (ETDEWEB)

A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described.

Post, Richard F. (Walnut Creek, CA)

1998-01-01

369

A flexible cruciform journal bearing mount  

Science.gov (United States)

Flexible mount achieves low roll, pitch and yaw stiffnesses while maintaining high radial stiffness by holding bearing pad in fixed relationship to deep web cruciform member and holding this member in fixed relationship to bearing support. This mount has particular application in small, high performance gas turbines.

Frost, A. E.; Geiger, W. A.

1973-01-01

370

Space-filling bearings in three dimensions  

CERN Multimedia

We present the first space-filling bearing in three dimensions. It is shown that a packing which contains only loops with even number of spheres can be constructed in a self-similar way and that it can act as a three dimensional bearing in which spheres can rotate without slip and with negligible torsion friction.

Baram, R M; Rivier, N

2003-01-01

371

Precision instrumentation for rolling element bearing characterization.  

Science.gov (United States)

This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings. PMID:17411223

Marsh, Eric R; Vigliano, Vincent C; Weiss, Jeffrey R; Moerlein, Alex W; Vallance, R Ryan

2007-03-01

372

Precision instrumentation for rolling element bearing characterization  

International Nuclear Information System (INIS)

This article describes an instrument to measure the error motion of rolling element bearings. This challenge is met by simultaneously satisfying four requirements. First, an axial preload must be applied to seat the rolling elements in the bearing races. Second, one of the races must spin under the influence of an applied torque. Third, rotation of the remaining race must be prevented in a way that leaves the radial, axial/face, and tilt displacements free to move. Finally, the bearing must be fixtured and measured without introducing off-axis loading or other distorting influences. In the design presented here, an air bearing reference spindle with error motion of less than 10 nm rotates the inner race of the bearing under test. Noninfluencing couplings are used to prevent rotation of the bearing outer race and apply an axial preload without distorting the bearing or influencing the measurement. Capacitive displacement sensors with 2 nm resolution target the nonrotating outer race. The error motion measurement repeatability is shown to be less than 25 nm. The article closes with a discussion of how the instrument may be used to gather data with sufficient resolution to accurately estimate the contact angle of deep groove ball bearings

2007-03-01

373

Self-adjusting magnetic bearing systems  

Energy Technology Data Exchange (ETDEWEB)

A self-adjusting magnetic bearing automatically adjusts the parameters of an axially unstable magnetic bearing such that its force balance is maintained near the point of metastable equilibrium. Complete stabilization can be obtained with the application of weak restoring forces either from a mechanical bearing (running at near-zero load, thus with reduced wear) or from the action of residual eddy currents in a snubber bearing. In one embodiment, a torque is generated by the approach of a slotted pole to a conducting plate. The torque actuates an assembly which varies the position of a magnetic shunt to change the force exerted by the bearing. Another embodiment achieves axial stabilization by sensing vertical displacements in a suspended bearing element, and using this information in an electrical servo system. In a third embodiment, as a rotating eddy current exciter approaches a stationary bearing, it heats a thermostat which actuates an assembly to weaken the attractive force between the two bearing elements. An improved version of an electromechanical battery utilizing the designs of the various embodiments is described. 7 figs.

Post, R.F.

1998-07-21

374

Can polar bear hairs absorb environmental energy?  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A polar bear (Ursus maritimus) has superior ability to survive in harsh Arctic regions, why does the animal have such an excellent thermal protection? The present paper finds that the unique labyrinth cavity structure of the polar bear hair plays an important role. The hair can not only prevent body temperature loss but can also absorb energy from the environment.

He Ji-Huan; Wang Qing-Li; Sun Jie

2011-01-01

375

Axially and Radially Controllable Magnetic Bearing.  

Science.gov (United States)

To overcome the problems of bearing friction in relatively large spinning structures, a pair of magnetic bearings were used to suspend or levitate the ends of the axis of a spinning rotor relative to a stator by magnetic forces or flux concentrated in rel...

L. J. Veillette

1974-01-01

376

Friction coefficients of PTFE bearing liner  

Science.gov (United States)

Data discusses frictional characteristics of PTFE (polytetrafluoroethylene) under temperature extremes and in vacuum environment. Tests were also run on reduced scale hardware to determine effects of vacuum. Data is used as reference by designers of aircraft-control system rod-end bearings and for bearings used in polar regions.

Daniels, C. M.

1979-01-01

377

Development of gadolinia bearing fuel for PWR  

International Nuclear Information System (INIS)

In the PWR power plants in Japan, the long-period operation cycle was extended legally to a maximum of 13 months from the conventional about 9 months in fiscal 1980. With this move, as a new type of fuel with burnable-poison-rod function, the development was started of gadolinia-bearing (gadolinium oxide) fuel, gadolinia being contained in the fuel pellets. The basic technology studies were completed in fiscal 1984. Actual irradiation of the fuel in Unit 2 of the Oi Power Station was then started in July 1984, demonstrating validity of the design. Meanwhile, the rapid power-up fest and the fuel center temperature measurement are conducted in an overseas reactor from fiscal 1983. The following are described: functions of the burnable absorber, the need for gadolinia-bearing fuel, experiences with gadolinia-bearing fuel, problems in the design and production of gadolinia-bearing fuel, the development of gadolinia-bearing fuel. (Mori, K.)

378

Cracks in a roller-bearing  

Directory of Open Access Journals (Sweden)

Full Text Available Bearings are among the most important components of electromotors, pumps, compressors and other processing equipment. After 30 years of work some non-destructive and metallographic examinations were carried out on a single-row cylindrical roller-bearing. A non-destructive liquid-penetrant testing revealed crack indications on an inner ring groove. When a sample of the roller-bearing outer ring was cut out for metallographic examination, new cracks were discovered that were not detected by the non-destructive testing. However, with the examination of the non-failed bearing it is possible to obtain useful information that can help us to decide how much of the remaining population of bearings with the same geometry and loading should be examined.

Celin, R.

2008-01-01

379

Marine bearing for a downhole drilling apparatus  

Energy Technology Data Exchange (ETDEWEB)

A bearing supports a rotatable shaft in a fluid environment. The bearing can be utilized to support a drive shaft connected to a drill bit in a downhole drilling apparatus. The drive shaft extends through a housing in which drilling fluid is flowing. Preferably, the bearing includes an inner elastomeric sleeve and an outer rigid sleeve attached to the interior side wall of the housing. The drive shaft has a wear sleeve attached for rotation therewith. The wear sleeve is rotatably received in the bearing inner sleeve. The inner sleeve is relatively short as compared with the drive shaft and absorbs radial loads imposed on the drive shaft. The bearing is lubricated by a portion of the drilling fluid in the housing which flows between the exterior side wall of the wear sleeve and the interior side wall of the inner sleeve.

Beimgraben, H.W.

1984-07-31

380

Rotating anode X-ray tube with axial magnetic bearing and radial sliding bearing  

International Nuclear Information System (INIS)

This patent describes a bearing system for a rotating anode X-ray tube that consists of an axial magnetic bearing and at least one radial sliding bearing. The bearing surfaces are coated with a molecular lubricating layer of either liquid gallium or a liquid gallium alloy, which does not substantially impair the mutually cooperating metallic bearing surfaces. This gives minimal wear and noise generation and ensures cheap production. The X-ray tube construction described is particularly suitable for applications as a radiation source in medical X-ray diagnostics. (T.P.)

1979-01-01

 
 
 
 
381

Multiaxis Thrust Vectoring Using Axisymmetric Nozzles and Postexit Vanes on an F/A-18 Configuration Vehicle.  

Science.gov (United States)

A ground-based investigation was conducted on an operational system of multiaxis thrust vectoring using postexit vanes around an axisymmetric nozzle. This thrust vectoring system will be tested on the NASA F/A-18 High Alpha Research Vehicle (HARV) aircraf...

A. H. Bowers G. K. Noffz S. B. Grafton M. L. Mason L. R. Peron

1991-01-01

382

Influence of ancient thrust faults on the hydrogeology of the Blue Ridge Province.  

Science.gov (United States)

The Blue Ridge Province contains ubiquitous northeast-southwest-trending thrust faults or smaller thrust "slivers" that greatly impact the nature and character of ground water flow in this region. Detailed investigations at a field site in Floyd County, Virginia, indicate that high-permeability zones occur in the brittle crystalline rocks above these thrust faults. Surface and borehole geophysics, aquifer tests, and chlorofluorocarbon and geochemical data reveal that the shallow saprolite aquifer is separated from the deeper fault-zone aquifer by a low-fracture permeability bedrock confining unit, the hydraulic conductivity of which has been estimated to be six orders of magnitude less than the conductivity of the fault zones at the test site. Within the Blue Ridge Province, these fault zones can occur at depths of 300 m or more, can contain a significant amount of storage, and yield significant quantities of water to wells. Furthermore, it is expected that these faults may compartmentalize the deep aquifer system. Recharge to and discharge from the deep aquifer occurs by slow leakage through the confining unit or through localized breach zones that occur where quartz accumulated in high concentrations during metamorphism and later became extensively fractured during episodes of deformation. The results of this investigation stress the importance of thrust faults in this region and suggest that hydrogeologic models for the Blue Ridge Province include these ancient structural features. Faults in crystalline-rock environments may not only influence the hydrology, they may dominate the flow characteristics of a region. PMID:15882322

Seaton, William J; Burbey, Thomas J

2005-01-01

383

Deepwater North West Borneo: hydrocarbon accumulation in an active fold and thrust belt  

Energy Technology Data Exchange (ETDEWEB)

In the deepwater acreage of North West Borneo an active offshore fold and thrust belt hosts a number of proven hydrocarbon accumulations and promises to deliver considerable additional hydrocarbon volumes as a result of ongoing exploration campaigns. Typical trapping geometries observed in this Neogene large-scale linked fold and thrust belt are hanging-wall anticlines, foreland folds and ridges and sub-thrust footwall cut-offs. Commercial drilling targets lie within the deformed Miocene and Pliocene sediment pile and these have been charged with oil and gas from a petroleum system that is still active at the present day. A major challenge here is to avoid drilling traps that have expelled their hydrocarbons during periods of active deformation and uplift in recent geological time. Studies of tectonic deformation phases are beginning to illuminate some key controls on trap formation and hydrocarbon retention history. This paper focuses on providing an overview of the North West Borneo deepwater fold and thrust belt and introduces some key issues and challenges for future hydrocarbon exploration in the region. (author)

Ingram, G.M.; Chisholm, T.J.; Grant, C.J. [Shell Malaysia Exploration and Production, Sarawak (Malaysia). Deepwater Exploration; Hedlund, C.A. [Shell International Exploration and Production, Houston, TX (United States). Deepwater Services; Stuart-Smith, P.; Teasdale, J. [SRK Consulting Ltd., Canberra (Australia)

2004-08-01

384

Wall pressure and thrust of a dual bell nozzle in a cold gas facility  

Science.gov (United States)

A dual-bell nozzle has been tested in the ONERA-R2Ch wind tunnel within the CNES PERSEUS program. The wall pressure distributions and the thrust for the two flow regimes have been characterized in the nozzle pressure ratio (NPR) range from 51 up to 597. A hysteresis on the transition NPR between the two flow regimes has been observed according to the evolution of NPR. The duration for the switch between the two flow regimes is less than 10 ms. The hysteresis of about 20% on the NPR has also a direct effect on the thrust. The total thrust of the dual-bell nozzle becomes higher than the thrust of the isolated base nozzle without extension for NPR > 1500. The hysteresis phenomenon has been modeled with the use of supersonic separation criteria and by making the assumption that incipient separation occurs immediately after the transition for increasing NPRs, while effective separation occurs just before the transition for decreasing NPRs.

Reijasse, P.; Coponet, D.; Luyssen, J.-M.; Bar, V.; Palerm, S.; Oswald, J.; Amouroux, F.; Robinet, J.-C.; Kuszla, P.

2011-10-01

385

Thrust Estimates of a Partially Filled Multi-Cycle Pulse Detonation Rocket Engine  

Science.gov (United States)

Partially filled multi-cycle operation usually happens in pulse detonation rocket engines (PDREs). Thrust estimates of PDREs under such operating conditions will provide significant reference for relevant studies. An analytical model for thrust estimates is proposed in the present study. This model is based on Wintenberger' model for impulse calculation and empirical formula for specific impulse prediction of partially filled tubes; moreover, it takes into account performance penalty created by obstacles preliminarily, which are introduced to accelerate deflagration to detonation transition. Four specific analytical models are developed according to three previously proposed empirical formulas and a fitting one proposed for partial filling effect. Comparisons between model predictions and experimental measurements are carried out to validate the reliability of the models. It is found that the models make reasonable estimates and one of the models performs very well over a wide range of conditions. Discussion and analysis on the proposed model and partial filling effect are also performed in this study. Although there are many other factors that should be considered in evaluating thrust of partially filled multi-cycle PDREs, the present study supplies a rapid and effective means for thrust estimation and provides some modeling ideas meanwhile.

Wang, Ke; Fan, Wei

2013-09-01

386

Study on development of ejector of Bubble Jet Engine (BJE) - measurement of thrust -  

Energy Technology Data Exchange (ETDEWEB)

The AUV (Autonomous Under-water Vehicle), which is used for the present seabed investigations, has obtained the thrust with the screw driven by the battery. However, it has a disadvantage because of its size and cost. Therefore, this research is carried out to propose the Bubble Jet Engine (BJE) as an alternative propulsion device. It can directly transform combustion energy into kinetic energy, so it is expected that BJE can also rise the level of propulsion efficiency. This research aims at measuring exhaled mass flow rate and thrust to design ejectors, which become the core of BJE, and exploring practical possibility of BJE. Vertical type gas-water ejector experimental apparatus for measuring water entrainment was employed in order to understand the characteristics of operation conditions, such as inlet distance, air pressure of nozzle, diameter of nozzle, and so on. In addition, experiments for measuring the thrust in the condition of ejector were executed with horizontal type apparatus in water. However, the influence of the ejector to improve thrust can't have been recognized with high-pressure air at room temperature yet.

Ono, B; Nakashima, K; Shigematsu, T; Morishita, K, E-mail: ono@post.cc.sasebo.ac.j [Sasebo National College of Technology1-1, Okishin-cho, Sasebo City, Nagasaki Pref., 857-1193 (Japan)

2009-02-01

387

Rapid design and optimization of low-thrust rendezvous/interception trajectory for asteroid deflection missions  

Science.gov (United States)

Asteroid deflection techniques are essential in order to protect the Earth from catastrophic impacts by hazardous asteroids. Rapid design and optimization of low-thrust rendezvous/interception trajectories is considered as one of the key technologies to successfully deflect potentially hazardous asteroids. In this paper, we address a general framework for the rapid design and optimization of low-thrust rendezvous/interception trajectories for future asteroid deflection missions. The design and optimization process includes three closely associated steps. Firstly, shape-based approaches and genetic algorithm (GA) are adopted to perform preliminary design, which provides a reasonable initial guess for subsequent accurate optimization. Secondly, Radau pseudospectral method is utilized to transcribe the low-thrust trajectory optimization problem into a discrete nonlinear programming (NLP) problem. Finally, sequential quadratic programming (SQP) is used to efficiently solve the nonlinear programming problem and obtain the optimal low-thrust rendezvous/interception trajectories. The rapid design and optimization algorithms developed in this paper are validated by three simulation cases with different performance indexes and boundary constraints.

Li, Shuang; Zhu, Yongsheng; Wang, Yukai

2014-02-01

388

Reynolds Number Effects on Thrust Coefficients and PIV for Flapping Wing Micro Air Vehicles.  

Science.gov (United States)

For the last several years the Air Force Institute of Technology (AFIT) has conducted research in aerodynamics for flapping wing micro air vehicles (MAVs). The focus of this research was to augment this effort by measuring thrust, velocity, and torque in ...

J. P. Tekell

2012-01-01

389

Tectonic evolution of a crustal-scale oblique ramp, Hellenides thrust belt, Greece  

Science.gov (United States)

This study investigates the tectonic evolution of the Omalos transverse zone, which served as a crustal-scale oblique ramp in the External Hellenides thrust belt on Crete island. The Omalos oblique ramp developed above an inherited Mesozoic fault zone that strikes NE-SW, oblique to the regional SSW-directed tectonic transport. During the Early Miocene-Pleistocene evolution of the thrust belt, the oblique ramp was repeatedly reactivated localizing deformation above the inherited structure. Geological and structural mapping combined with kinematic analysis of ductile and brittle structures suggest that the Omalos oblique ramp generated a local kinematic field, which deviated significantly from the regional kinematic pattern in the thrust belt. The most conspicuous feature in the tectonic evolution of the oblique ramp is a change from a ductile wrench-dominated to a brittle, primarily reverse faulting regime across the brittle-ductile transition, followed by brittle wrench deformation after the final exhumation of high-pressure (HP) rocks. Deflections of transport and compression orientations from the regional pattern are attributed to buttressing against basement-cover offsets produced by the pre-existing fault zone, to oblique ramping, and to transfer faulting, respectively. Our findings are potentially applicable to other examples of crustal-scale oblique thrust ramps in various tectonic settings.

Chatzaras, V.; Xypolias, P.; Kokkalas, S.; Koukouvelas, I.

2013-12-01

390

Static performance of nonaxisymmetric nozzles with yaw thrust-vectoring vanes  

Science.gov (United States)

A static test was conducted in the static test facility of the Langley 16 ft Transonic Tunnel to evaluate the effects of post exit vane vectoring on nonaxisymmetric nozzles. Three baseline nozzles were tested: an unvectored two dimensional convergent nozzle, an unvectored two dimensional convergent-divergent nozzle, and a pitch vectored two dimensional convergent-divergent nozzle. Each nozzle geometry was tested with 3 exit aspect ratios (exit width divided by exit height) of 1.5, 2.5 and 4.0. Two post exit yaw vanes were externally mounted on the nozzle sidewalls at the nozzle exit to generate yaw thrust vectoring. Vane deflection angle (0, -20 and -30 deg), vane planform and vane curvature were varied during the test. Results indicate that the post exit vane concept produced resultant yaw vector angles which were always smaller than the geometric yaw vector angle. Losses in resultant thrust ratio increased with the magnitude of resultant yaw vector angle. The widest post exit vane produced the largest degree of flow turning, but vane curvature had little effect on thrust vectoring. Pitch vectoring was independent of yaw vectoring, indicating that multiaxis thrust vectoring is feasible for the nozzle concepts tested.

Mason, Mary L.; Berrier, Bobby L.

1988-01-01

391

On the thrust distribution in e/sup +/e/sup -/ annihilation  

CERN Multimedia

The thrust distribution calculated in perturbative QCD through to O( alpha /sub s//sup 2/) is presented. The results, which come from an elaboration of previously published formulae, show that the O( alpha /sub s//sup 2/) correction at present energies is large and positive in agreement with the previously obtained results of many groups. (13 refs).

Ellis, Richard Keith

1981-01-01

392

The Application of Gridded Ion Thrusters to High Thrust, High Specific Impulse Nuclear-Electric Missions  

Science.gov (United States)

Gridded ion thrusters are usually regarded as very efficient devices which can operate at high values of specific impulse (SI), of the order of 2800 to 5000 s, but with an inherently low thrust and thrust density. However, this latter limitation is due to the restricted power available from present spacecraft. It is shown in this paper that a very much enhanced thrust density can be provided if a nuclear fission power source is utilised, with an electrical output in the 100 kW to multi-MW range, and if higher values of SI can be employed. In that case, use can be made of a 4-grid ion extraction and acceleration system, permitting present thrust densities in the range 0.1 to 0.9 mN/cm2 to be increased to as much as 28 mN/cm2. Corresponding values of SI depend critically upon the propellant used and vary from about 8000 s to as high as 150,000 s. As an example of a possible application of this technology, a manned mission to Mars is considered, which employs existing space vehicles and launchers to the maximum possible extent in order to minimise cost. It is shown that such a mission is viable if a nuclear reactor system with an electrical output of about 1 MW is available, with a mass-to-power ratio of less than 20 kg/kW.

Fearn, D. G.

393

Study on development of ejector of Bubble Jet Engine (BJE) - measurement of thrust -  

International Nuclear Information System (INIS)

The AUV (Autonomous Under-water Vehicle), which is used for the present seabed investigations, has obtained the thrust with the screw driven by the battery. However, it has a disadvantage because of its size and cost. Therefore, this research is carried out to propose the Bubble Jet Engine (BJE) as an alternative propulsion device. It can directly transform combustion energy into kinetic energy, so it is expected that BJE can also rise the level of propulsion efficiency. This research aims at measuring exhaled mass flow rate and thrust to design ejectors, which become the core of BJE, and exploring practical possibility of BJE. Vertical type gas-water ejector experimental apparatus for measuring water entrainment was employed in order to understand the characteristics of operation conditions, such as inlet distance, air pressure of nozzle, diameter of nozzle, and so on. In addition, experiments for measuring the thrust in the condition of ejector were executed with horizontal type apparatus in water. However, the influence of the ejector to improve thrust can't have been recognized with high-pressure air at room temperature yet.

2009-02-01

394

Deformation characterization of a regional thrust zone in the northern Rif (Chefchaouen, Morocco)  

Science.gov (United States)

This paper provides the structural analysis of the Chefchaouen area in the northern Rif. Here the Dorsale Calcaire superposes, by means of an excellently exposed thrust fault, onto the Predorsalian succession in turn tectonically covering the Massylian Unit. Hanging wall carbonates of the Dorsale Calcaire Unit form a WSW-verging regional fold with several parasitic structures, deformed by late reverse faults in places indicating an ENE vergence. A 200 m thick shear zone characterizes the upper part of the Predorsalian succession, located at footwall of the Dorsale Calcaire Unit. Here the dominantly pelitic levels are highly deformed by (i) C? type shear bands indicating a mean WSW tectonic transport and (ii) conjugate extensional shear planes marking an extension both orthogonal and parallel to the shear direction. The Massylian Unit is characterized by a strain gradient increasing toward the tectonic contact with the overlying Predorsalian succession, where the dominantly pelitic levels are so highly deformed so as appearing as a broken formation. Such as the previous succession, conjugate extensional shear bands and normal faults indicate a horizontal extension parallel to the thrust front synchronous with the mainly WSW-directed overthrusting. The whole thrust sheet pile recorded a further shortening, characterized by a NW-SE direction, expressed by several reverse and thrust faults and related folds. Finally strike-slip and normal faults were the last deformation structures recorded in the analyzed rocks. A possible tectonic evolution for these successions is provided. In the late Burdigalian, the Dorsale Calcaire Unit tectonically covered the Predorsalian succession and together the Massylian Unit. The latter two successions were completely detached from their basement and accreted in the orogenic wedge within a general NE-SW shortening for the analyzed sector of the northern Rif. At lithosphere scale the thrust front migration was driven by roll back and slab tear mechanisms producing a synchronous arching and related counterclockwise rotation of the tectonic prism along the African margin. Radial displacement involved extension parallel to the thrust front well-recorded in the analyzed rocks. The NE-SW shortening, probably acting in the Tortonian-Pliocene interval, was related to the final compression of the Rif Chain resulting in out-of-sequence thrusts affecting the whole orogenic belt.

Vitale, Stefano; Zaghloul, Mohamed Najib; Tramparulo, Francesco D.'Assisi; El Ouaragli, Bilal

2014-07-01

395

Predicting stress distributions in fold-and-thrust belts and accretionary wedges by optimization  

Science.gov (United States)

The objective is to demonstrate that the equilibrium element method (EEM) provides the stress distribution in geometrical models of folds, relevant to fold-and-thrust belts as well as accretionary wedges. The core of the method, inherited from limit analysis, is the search for an optimum stress field that (1) is in equilibrium, (2) remains everywhere below or equal to the maximum strength of the rock, and (3) balances the largest possible applied tectonic force. This force and the associated stress field are interpreted as those at the onset of rupture. The method makes no appeal to the rock rheology nor to its elasticity, except for its maximum strength described here with the Coulomb criterion. The stress fields are discretized by elements covering the whole domain and allowing for discontinuities. The example chosen to illustrate the potential of the EEM and to validate our implementation is the thrusting of a rectangular sheet over a flat and weak décollement. The EEM reproduces the solution proposed by Hafner (1951) on the basis of linear elasticity, as long as the strength limit is not reached in the bulk of the domain. The EEM shows in addition that failure in the bulk prevents the activation of the décollement. The EEM is then applied to two fault-bend folds, with known ramp and flat décollement, with and without relief buildup. It is shown that the transition from the flat to the ramp hanging walls occurs through a narrow fan defining the back thrust. The predicted dip of this back thrust decreases with increase in the ramp friction angle, the relief buildup, as well as the ramp curvature. A sharp increase and then a sharp decrease in the magnitudes of the equivalent shear stress and of the mean stress are observed as one moves from the lower flat, through the back thrust up the ramp. If the ramp friction angle is too large, or the relief too important, the EEM predicts the initiation of a new thrust rooting at the back wall, instead of activating the proposed ramp. The application to detect the incipient thrust system within the toe of Nankai's accretionary wedge, southeast coast of Japan, is proposed in the auxiliary material.

Souloumiac, P.; Leroy, Y. M.; Maillot, B.; KrabbenhøFt, K.

2009-09-01

396

Morphotectonics of the central Muertos thrust belt and Muertos Trough (northeastern Caribbean)  

Science.gov (United States)

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

Granja, Bruna, J. L.; ten, Brink, U. S.; Carbo-Gorosabel, A.; Munoz-Martin, A.; Gomez, Ballesteros, M.

2009-01-01

397

Sedimentation controls on thin-skinned fold-and-thrust belts and application to the Southern Pyrenees  

Science.gov (United States)

The interactions between tectonics and surface processes in mountainous area are well known now for being of first-order importance on the development of an orogenic belt. Among these, the feedback between thin-skinned deformation in external zones and wedge-top sedimentation can be very important when the décollement level is efficient and the amount of sediments important enough. Therefore, we use an Arbitrary Lagrangian Eulerian finite-element model (Sopale) to model a thin-skinned fold-and-thrust belt at upper crustal scales (7 km depth and 200 km length) and its response to several patterns of wedge-top sedimentation. Sopale takes into account the main features and processes that influence the development of a fold-and-thrust belt including detachment horizons, strain-softening, flexural isostasy, and erosion and sedimentation processes. Initial, more conceptual modeling focuses on wedge development coupled with syn-orogenic sedimentation. Wedge-top sedimentation directly affects the taper angle and clearly modifies the behavior of the wedge; a clear relationship between average thrust-sheet length and the thickness of syn-tectonic sediments is highlighted. Subsequently, a sediment cover that progrades towards the foreland with time is added to reproduce the late syn-orogenic burial of the southern Pyrenean fold-and-thrust belt by conglomerates. As a matter of fact, both syn- and post- orogenic deposits may have influenced the range evolution in the Southern Central Pyrenees. During middle to late Eocene, thrust deformation in the Pyrenean fold-and-thrust belt migrated to the south with in-sequence piggy-back thrust development with long thrust sheets and important sedimentation. From Oligocene to Miocene, combined thermochronometric, modeling and field studies showed that conglomerates sourced from the axial zone buried the fold-and-thrust belt until the Ebro foreland basin. At the same time thrust activity migrated from the front to the internal parts of the orogen reactivating major proximal thrusts in the foreland fold and thrust belt and in the south of the Axial Zone, but the reason for the out of sequence activity is still a matter a debate. We will investigate the causes for out-of-sequence thrust activity and the possible relationship with conglomeratic wedge top sedimentation, as well as the effects of different modes of deposition (prograding or aggrading) on the fold-and-thrust belt.

Fillon, Charlotte; Huismans, Ritske; van der Beek, Peter

2014-05-01

398

Linear Test Bed. Volume 2: Test Bed No. 2. [linear aerospike test bed for thrust vector control  

Science.gov (United States)

Test bed No. 2 consists of 10 combustors welded in banks of 5 to 2 symmetrical tubular nozzle assemblies, an upper stationary thrust frame, a lower thrust frame which can be hinged, a power package, a triaxial combustion wave ignition system, a pneumatic control system, pneumatically actuated propellant valves, a purge and drain system, and an electrical control system. The power package consists of the Mark 29-F fuel turbopump, the Mark 29-0 oxidizer turbopump, a gas generator assembly, and propellant ducting. The system, designated as a linear aerospike system, was designed to demonstrate the feasibility of the concept and to explore technology related to thrust vector control, thrust vector optimization, improved sequencing and control, and advanced ignition systems. The propellants are liquid oxygen/liquid hydrogen. The system was designed to operate at 1200-psia chamber pressure at an engine mixture ratio of 5.5. With 10 combustors, the sea level thrust is 95,000 pounds.

1974-01-01

399

Structural geology of the Sunset Lake slice, Taconic fold thrust belt, western Vermont  

Energy Technology Data Exchange (ETDEWEB)

The Sunset Lake slice is purported to be the lowest thrust sheet in the Taconics. Only a small area is underlain by this thrust sheet and the region has remained unmapped since the regional compilation by Zen. Apparently most (if not all) of the early mapping of this area was done by John Rodgers who comments on it in his comment to Rowley and Kidd. Since the time of that early mapping, significant new aspects of Taconic stratigraphy have come to light which alter the structures mapped. The authors have remapped the greater portion of the Sunset Lake slice with several questions in mind: Is the stratigraphy in this slice the same as in the Giddings Brook slice immediately above Are there differences in the structural history of the two slices The Sunset lake slice contains the same stratigraphy defined in the Fairhaven, Vt. area by Rowley, Kidd and Delano from the Bomoseen Fm. up to the Hatch Hill Fm. The upper part of the stratigraphy, however, is not present. The structures displayed by the new mapping indicate that the rocks experienced two episodes of folding prior to their final thrust emplacement. The early folds are isoclinal, with N-S striking axial planes and shallowly plunging axes. These folds are responsible for repetition of the stratigraphy. The later folds are more open and have an axial plane crenulation cleavage. Thus, the structural history of the Sunset Lake slice is identical to the Giddings Brook slice and, if it truly is a separate thrust slice, it probably is not much less further traveled than the larger slice above it. The surrounding middle Ordovician flysch is both cleaved and uncleaved. On the eastern side of the thrust sheet cleaved flysch lies structurally above the taconic rocks in fault contact. Thus, the margins of the sheet, at least in part, are flysch-on-flysch and, thus, difficult to map with accuracy.

Carpenter, D.; Day, K. (Colgate Univ., Hamilton, NY (United States))

1993-03-01

400

Genetic control of biennial bearing in apple.  

Science.gov (United States)

Although flowering in mature fruit trees is recurrent, floral induction can be strongly inhibited by concurrent fruiting, leading to a pattern of irregular fruiting across consecutive years referred to as biennial bearing. The genetic determinants of biennial bearing in apple were investigated using the 114 flowering individuals from an F(1) population of 122 genotypes, from a 'Starkrimson' (strong biennial bearer)×'Granny Smith' (regular bearer) cross. The number of inflorescences, and the number and the mass of harvested fruit were recorded over 6 years and used to calculate 26 variables and indices quantifying yield, precocity of production, and biennial bearing. Inflorescence traits exhibited the highest genotypic effect, and three quantitative trait loci (QTLs) on linkage group (LG) 4, LG8, and LG10 explained 50% of the phenotypic variability for biennial bearing. Apple orthologues of flowering and hormone-related genes were retrieved from the whole-genome assembly of 'Golden Delicious' and their position was compared with QTLs. Four main genomic regions that contain floral integrator genes, meristem identity genes, and gibberellin oxidase genes co-located with QTLs. The results indicated that flowering genes are less likely to be responsible for biennial bearing than hormone-related genes. New hypotheses for the control of biennial bearing emerged from QTL and candidate gene co-locations and suggest the involvement of different physiological processes such as the regulation of flowering genes by hormones. The correlation between tree architecture and biennial bearing is also discussed. PMID:21963613

Guitton, Baptiste; Kelner, Jean-Jacques; Velasco, Riccardo; Gardiner, Susan E; Chagné, David; Costes, Evelyne

2012-01-01

 
 
 
 
401

19 CFR 133.21 - Articles bearing counterfeit trademarks.  

Science.gov (United States)

...2009-04-01 2009-04-01 false Articles bearing counterfeit trademarks. 133.21 ...NAMES, AND COPYRIGHTS Importations Bearing Registered and/or Recorded Trademarks...Recorded Trade Names § 133.21 Articles bearing counterfeit trademarks. (a)...

2009-04-01

402

How Mother Bear Taught the Children about Lead  

Science.gov (United States)

... Share How Mother Bear Taught the Children about Lead Download the Mother Bear Books and Teacher's Guide ... Whiskers? How Mother Bear Taught the Children about Lead You and Your Genes The Lead Busters Club ...

403

49 CFR 230.102 - Tender plain bearing journal boxes.  

Science.gov (United States)

... 2010-10-01 false Tender plain bearing journal boxes. 230.102 Section 230.102 Transportation...Running Gear § 230.102 Tender plain bearing journal boxes. Plain bearing journal boxes with the following defects shall be...

2010-10-01