Note: This page contains sample records for the topic stators diagnostico del from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Segmented stator assembly  

DOEpatents

An electric machine and stator assembly are provided that include a continuous stator portion having stator teeth, and a tooth tip portion including tooth tips corresponding to the stator teeth of the continuous stator portion, respectively. The tooth tip portion is mounted onto the continuous stator portion.

Lokhandwalla, Murtuza; Alexander, James Pellegrino; El-Refaie, Ayman Mohamed Fawzi; Shah, Manoj Ramprasad; Quirion, Owen Scott

2013-04-02

2

Electrical stator  

DOEpatents

An electrical stator of an electromagnetic pump includes first and second spaced apart coils each having input and output terminals for carrying electrical current. An elongate electrical connector extends between the first and second coils and has first and second opposite ends. The connector ends include respective slots receiving therein respective ones of the coil terminals to define respective first and second joints. Each of the joints includes a braze filler fixedly joining the connector ends to the respective coil terminals for carrying electrical current therethrough.

Fanning, Alan W. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1994-01-01

3

Stator and method of assembly  

DOEpatents

The present application provides a stator. The stator may include a number of poles and a stator tip and cooling assembly. The stator tip and cooling assembly may include a number of stator tips with a number of cooling tubes adjacent thereto such that the stator tips align with the poles and the cooling tubes cool the poles.

Alexander, James Pellegrino; El-Refaie, Ayman Mohamed Fawzi; Shen, Xiaochun

2013-06-18

4

Composite fan stator assembly  

SciTech Connect

A composite fan stator assembly is described for a gas turbine engine having at least two fan rotor stages, the composite stator assembly comprising: an annular composite fan case assembly including an access port, the fan case assembly circumferentially disposed around first and second fan rotor stage locations, a composite fan stator stage supported by and extending radially inward of the fan case assembly and axially disposed between the two fan rotor stage locations, the fan stator stage includes at least one removable vane segment accessible for removal through the access port for assembly and reassembly, the composite fan case assembly including a separable composite forward fan case assembly and a separable composite aft fan case assembly spaced axially aft of the forward fan case assembly, the forward fan case assembly being bolted to the aft fan case assembly, wherein the composite fan stator stage is axially and radially trapped and supported by the forward and aft fan case assemblies. A composite stator vane assembly comprising: a composite inner shroud, a composite outer shroud disposed radially outward of the inner shroud, a plurality of vanes disposed between the shrouds, the vanes including a suction side and a pressure side and radially inner and outer roots, the roots extending through platforms of corresponding ones of the inner and outer shrouds, four box-type attachment elements corresponding to curved suction and pressure sides of the inner and outer roots, the box-type attachment elements having two connected legs angled with respect to each other, a first one of the legs extending along, conforming to the curve of, and bonded to a corresponding one of the airfoil root sides, and a second one of the legs extending along and bonded to a composite shroud surface.

Donges, G.L.

1993-07-13

5

Stator winding monitoring  

Microsoft Academic Search

Partial discharge tests can determine which motor and generator stator windings are experiencing insulation problems. A deteriorated winding has a PD activity which can be 30 times or more higher than a winding in good condition. This great difference in PD activity enables even nonspecialized maintenance personnel to identify the few motors or generators in a company which need further

G. Stone; J. Kapler

1998-01-01

6

Electromagnetic pump stator core  

DOEpatents

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter.

Fanning, Alan W. (San Jose, CA); Olich, Eugene E. (Aptos, CA); Dahl, Leslie R. (Livermore, CA)

1995-01-01

7

Banded electromagnetic stator core  

DOEpatents

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1994-01-01

8

Banded electromagnetic stator core  

DOEpatents

A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

Fanning, Alan W. (San Jose, CA); Gonzales, Aaron A. (San Jose, CA); Patel, Mahadeo R. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1996-01-01

9

Electromagnetic pump stator core  

DOEpatents

A stator core for supporting an electrical coil includes a plurality of groups of circumferentially abutting flat laminations which collectively form a bore and perimeter. A plurality of wedges are interposed between the groups, with each wedge having an inner edge and a thicker outer edge. The wedge outer edges abut adjacent ones of the groups to provide a continuous path around the perimeter. 21 figures.

Fanning, A.W.; Olich, E.E.; Dahl, L.R.

1995-01-17

10

Stator rotor tools  

NASA Technical Reports Server (NTRS)

An apparatus and method for removing and reinserting base member segments in an arcuate slot in an engine part are described. Each base member separately includes blades or stators, holding the engine part in place while manipulating fingers or an arm onto an interfitting abutting relationship with most of the blades. A torque force is applied to the base of the blades to move a base member relative to such an arcuate slot.

Diamond, D. D. (inventor)

1978-01-01

11

Electromagnetic pump stator coil  

DOEpatents

An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom.

Fanning, Alan W. (San Jose, CA); Dahl, Leslie R. (Livermore, CA)

1996-01-01

12

Electromagnetic pump stator coil  

DOEpatents

An electrical stator coil for an electromagnetic pump includes a continuous conductor strip having first and second terminals at opposite ends thereof and an intermediate section disposed therebetween. The strip is configured in first and second coil halves, with the first coil half including a plurality of windings extending from the first terminal to the intermediate section, and the second coil half including a plurality of windings extending from the second terminal to the intermediate section. The first and second coil halves are disposed coaxially, and the first and second terminals are disposed radially inwardly therefrom with the intermediate section being disposed radially outwardly therefrom. 9 figs.

Fanning, A.W.; Dahl, L.R.

1996-06-25

13

Stator-rotor piston internal combustion engine  

Microsoft Academic Search

This patent describes a stator-rotor piston internal combustion engine, comprising: a pair of mirror-image stator halves having an inner section in abutment and operatively connected to one another; cylinders disposed in an outer section of the stator halves, the stator halves having an equal number of cylinders with one another, each cylinder having, a piston disposed therein, a single connecting

B. Ivanov; R. Ivanova

1986-01-01

14

Stator having selectively applied thermal conductivity coating  

SciTech Connect

This patent describes a gas turbine engine stator for surrounding a rotor including a plurality of circumferentially spaced blades, each having a tip. It comprises a stator flowpath surface adjacent and around the rotor blade tips to define a radial clearance therebetween; and means for controlling non-axisymmetric radial clearance which occurs between the stator flowpath surface and the blade tips.

Plemmons, L.W.; Oakes, W.C.; Kirkpatrick, R.A.

1992-07-07

15

Noise generated by rotor-stator interactions  

Microsoft Academic Search

Noise generation by rotor-stator interaction in an incompressible pipe flow has been experimentally investigated. The approach is to correlate the acoustic field to the interaction flow field around the rotor- stator stage. The flow field is investigated by both the surface-pressure and velocity measurements around the stator, while the noise signature (acoustic field) is measured by a microphone at a

Chung-Hsing Hu

1997-01-01

16

Laminated electromagnetic pump stator core  

DOEpatents

A stator core for an electromagnetic pump includes a plurality of circumferentially abutting tapered laminations extending radially outwardly from a centerline axis to collectively define a radially inner bore and a radially outer circumference. Each of the laminations includes radially inner and outer edges and has a thickness increasing from the inner edge toward the outer edge to provide a substantially continuous path adjacent the circumference. This pump is used in nuclear fission reactors. 19 figs.

Fanning, A.W.

1995-08-08

17

Rubbing Between Rotors And Stators  

NASA Technical Reports Server (NTRS)

Report describes experimental and numerical-simulation studies of dynamical effects of rubbing between rotors and stators in turbomachinery. Purpose of study to gain improved understanding of such rubbing phenomena, with view toward: contributing to techniques for diagnosis of rubbing (e.g., via analysis of vibrations); predicting more accurately limiting operating conditions; and improving design criteria to prevent rubbing damage in high-performance rotating machinery.

Muszynska, Agnes; Bently, Donald E.; Franklin, Wesley D.; Hayashida, Robert D.; Kingsley, Lori M.; Curry, Arthur E.

1990-01-01

18

Stators with improved conductor assembly and method of making same  

DOEpatents

A stator includes a stator core, a plurality of slots, and a conductor. The plurality of slots are formed within the stator core. The conductor is disposed continuously within at least two of the plurality of openings.

Dang, Dang Dinh; Blissenbach, Rolf; Schauer, David; Wattleworth, John; Milani, Michael; Hatch, Erik

2013-07-30

19

Study of controlled diffusion stator blading  

NASA Technical Reports Server (NTRS)

Tests were conducted on a high tip speed, highly loaded front compressor stage having low aspect ratio rotor and stator airfoils. The stator airfoils were designed by the controlled diffusion procedure recently developed by P&WA for designing transonic cascade airfoils. The rotor blades consisted of multiple-circular-arc airfoil sections. The stage had a tip speed of 442 m/sec (1450 ft/sec), a hub/tip ratio of 0.597, a rotor aspect ratio of 1.3, and a stator aspect ratio of 1.45. At design speed the rotor-stator stage achieved an adiabatic efficiency of 89.1% at design flow and pressure ratio. Surge margin was 14%. The stage efficiency exceeded the design goal by 0.6 percentage points. The rotor efficiency was 92.4%, exceeding design by 0.3 percentage points. The controlled diffusion stator demonstrated a lower minimum loss over the multiple-circular-arc stator from the root to 70 percent span. A surge diffusion factor of 0.72 was reached at both the rotor tip and the stator root. The NAS3-22008 program demonstrated its intent: high efficiency and loading levels with low aspect ratio blades and the controlled diffusion stator in the unfavorable front stage environment.

Behlke, R. F.; Brooky, J. D.; Canal, E.

1983-01-01

20

Stator well flows in axial compressors  

Microsoft Academic Search

This paper reports a study of the flow conditions in spaces often found beneath the stationary blades of modern compressors – stator wells. The design of the stator wells in a modern high-pressure turbofan can be a limiting factor. This study shows good comparison with existing experimental data upon the pressures and velocities in related geometries. The deleterious effects upon

H. K. Öztürk; A. B. Turner; P. R. N. Childs; F. J. Bayley

2000-01-01

21

Design and performance of controlled-diffusion stator compared with original double-circular-arc stator  

NASA Technical Reports Server (NTRS)

The capabilities of two stators, one with controlled-diffusion (CD) blade sections and one with double-circular-arc (DCA) blade sections, were compared. A CD stator was designed and tested that had the same chord length but half the blades of the DCA stator. The same fan rotor (tip speed, 429 m/sec; pressure ratio, 1.65) was used with each stator row. The design and analysis system is briefly described. The overall stage and rotor performances with each stator are compared, as are selected blade element data. The minimum overall efficiency decrement across the stator was approximately 1 percentage point greater with the CD balde sections than with the DCA blade sections.

Gelder, Thomas F.; Schmidt, James F.; Suder, Kenneth L.; Hathaway, Michael D.

1987-01-01

22

Design and performance of controlled-diffusion stator compared with original double-circular-arc stator  

NASA Technical Reports Server (NTRS)

The capabilities of two stators, one with controlled-diffusion (CD) blade sections and one with double-circular-arc (DCA) blade sections, were compared. A CD stator was designed and tested that had the same chord length but half the blades of the DCA stator. The same fan rotor (tip speed, 429 m/sec; pressure ratio, 1.65) was used with each stator row. The design and analysis system is briefly described. The overall stage and rotor performances with each stator are compared, as are selected blade element data. The minimum overall efficiency decrement across the stator was approximately 1 percentage point greater with the CD blade sections than with the DCA blade sections.

Gelder, Thomas F.; Schmidt, James F.; Suder, Kenneth L.; Hathaway, Michael D.

1987-01-01

23

Evaluation of ceramics for stator applications: Gas turbine engines interim report. Stator fabrication and evaluation  

NASA Technical Reports Server (NTRS)

The objective was to assess current ceramic materials, fabrication processes, reliability prediction, and stator durability when subjected to simulated automotive gas turbine engine operating conditions. Ceramic one-piece stators were fabricated of two materials, silicon nitride and silicon carbide, using two near-net-shape processes, slip casting and injection molding. Non-destructive evaluation tests were conducted on all stators identifying irregularities which could contribute to failures under durability testing. Development of the test rig and automatic control system for repeatably controlling air flow rate and temperature over a highly transient durability duty cycle is discussed. Durability results are presented for repeated thermal cycle testing of the ceramic one-piece stators. Two duty cycles were used, encompassing the temperature ranges of 704 to 1204 C (1300 to 2200 F) and 871 to 1371 C (1600 to 2500 F). Tests were conducted on 28 stators, accumulating 135,551 cycles in 2441 hours of hot testing. Cyclic durability for the ceramic one-piece stator was demonstrated to be in excess of 500 hours, accumulating over 28,850 thermal cycles. Ceramic interface forces were found to be the significant factor in limiting stator life rather than the scatter in material strength properties or the variation in component defects encountered.

Arnon, N.; Trela, W.

1983-01-01

24

Shorted stator induction generator for low wind speed power application  

Microsoft Academic Search

Shorted stator induction generator (IG) is presented for low wind speed power application. An analytical model is derived for predicting electrical performance of the generator while operating in regions 1 and 2 of turbine power versus wind speed curve. This paper determines an explicit optimal stator electrical speed of operation since the stator is disconnected from synchronism with the grid.

Adeola Balogun; Olorunfemi Ojo; Frank Okafor

2010-01-01

25

Control rod drive mechanism stator loss of coolant test  

Microsoft Academic Search

This report documents the stator loss of coolant test conducted at HEDL on the lead unit Control Rod Drive Mechanism (CRDM) in February, 1977. The purpose of the test was to demonstrate scram capability of the CRDM with an uncooled stator and to obtain a time versus temperature curve of an uncooled stator under power. Brief descriptions of the test,

L. Besel; R. Ibatuan

1977-01-01

26

Development of a generator stator insulation system  

NASA Astrophysics Data System (ADS)

The insulation of stator windings in generators is an old technology, dating to the turn of the century with kraft paper insulated, oil filled cables. Recently, two new classes of machines requiring much more advanced techniques of insulation have emerged. These generators are designed for relatively short duty in situations where light weight and small size are crucial to the overall mission, and mobility is a must. One class of machines uses superconducting windings to achieve small size. The other class consists of conventional generators designed to have extremely high power densities and specific powers. These machines represent a considerable engineering achievement, being significantly smaller than any previous generator. In one of these generators, manufactured by Bendix, substantial problems have been encountered in the stator winding insulation, because of the high fields dictated by the extremely high power density. This report presents the Hughes Aircraft Company approach and solution to these problems.

Buritz, R. S.

1983-04-01

27

All stator windings are not created equal  

Microsoft Academic Search

It is noted that modern high-voltage stator windings in very large hydro generators are subject to attack from many sources-thermal aging, high-intensity slot discharge, low-intensity partial discharge (corona), mechanical vibration, oil, and high electrical bar forces. Any of these can be detrimental to the total insulation system, and together can sometimes cause insulation failure. Each failure mechanism has its own

R. H. Rehder; V. R. Mulhall; V. A. Moore; D. G. McLaren

1988-01-01

28

Small axial turbine stator technology program  

NASA Technical Reports Server (NTRS)

An experimental investigation was conducted to determine the effects of surface finish, fillet radius, inlet boundary layer thickness, and free-stream inlet turbulence level on the aerodynamic performance of a small axial flow turbine stator. The principal objective of this program was to help understand why large turbine efficiency is not maintained when a large turbine is scaled to a smaller size. The stator used in this program as a one-sixth scale of a 762 mm (30 in.) diameter stator design with 50 vanes having a vane height of 17 mm (0.666 in.) and an aspect ratio of 1.77. A comprehensive overall test matrix was used to provide a complete engineering understanding of the effects of each variable over the full range of all the other variables. The range of each variable investigated was as follows: surface finish 0.1 micro (4 micro in.) to 2.4 micro (95 micro in.); boundary layer thickness 2 to 25 percent of channel height at each wall; fillet radius 0 mm (0 in.) to 1.0 mm (.040 in.) and turbulence 2 to 12 percent.

Brockett, W.; Kozak, A.

1982-01-01

29

A Survey of Methods for Detection of Stator-Related Faults in Induction Machines  

Microsoft Academic Search

As evidenced by industrial surveys, stator-related failures account for a large percentage of faults in induction machines. The objective of this paper is to provide a survey of existing techniques for detection of stator-related faults, which include stator winding turn faults, stator core faults, temperature monitoring and thermal protection, and stator winding insulation testing. The root causes of fault inception,

Rangarajan M. Tallam; Sang Bin Lee; Greg C. Stone; Gerald B. Kliman; Jiyoon Yoo; Thomas G. Habetler; Ronald G. Harley

2007-01-01

30

Effect of toothless stator design and core and stator conductors eddy current losses in permanent magnet generators  

Microsoft Academic Search

Some advantages of toothless stator design in high-speed permanent magnet generators are presented. A computer-aided method was implemented to study the effect of stator teeth on the eddy current loss in the stator conductors as well as the core loss in the laminations of high-speed permanent magnet generators. The computer-aided method was applied to a 75 kVA, 208 V, 400

A. A. Arkadan; R. Vyas; J. G. Vaidya; M. J. Shah

1992-01-01

31

Generator stator core vent duct spacer posts  

DOEpatents

Generator stator cores are constructed by stacking many layers of magnetic laminations. Ventilation ducts may be inserted between these layers by inserting spacers into the core stack. The ventilation ducts allow for the passage of cooling gas through the core during operation. The spacers or spacer posts are positioned between groups of the magnetic laminations to define the ventilation ducts. The spacer posts are secured with longitudinal axes thereof substantially parallel to the core axis. With this structure, core tightness can be assured while maximizing ventilation duct cross section for gas flow and minimizing magnetic loss in the spacers.

Griffith, John Wesley (Schenectady, NY); Tong, Wei (Clifton Park, NY)

2003-06-24

32

Stator Blade Row Geometry Modification Influence on Two-Stage, Axial-Flow Compressor Aerodynamic Performance.  

National Technical Information Service (NTIS)

The influence of stator row geometry modification on the aerodynamic performance of a two-stage, low-speed, axial-flow research compressor was assessed in the experiments described in this project. Stator geometry modifications tested included stator lead...

D. L. Tweedt T. H. Okiishi

1983-01-01

33

Structural stator spacers-the key to silent electrical machines  

Microsoft Academic Search

This paper presents a powerful new design aspect to reduce acoustic noise and vibration of electro-magnetic origin for electrical machines, by introducing improved slot wedges referred to as “structural stator spacers”. These spacers, by using a very stiff dielectric and nonmagnetic material, a modified shape and small modifications to the stator laminations not only secure the windings and reduce windage

P. O. Rasmussen; J. Andreasen; J. M. Pijanowski

2001-01-01

34

9 MJ range gun compulsator stator design and fabrication  

Microsoft Academic Search

The stator of a 9 MJ range gun compulsator consists of a multiturn compensating winding with a laminated stainless steel support structure, an aluminum excitation field coil and support structure, a stainless steel stator casing and main end plates, hydrostatic bearings, seals, support pedestal, and current collection mechanisms for the field excitation and main armature circuits. The two-pole compensating winding

J. D. Herbst; K. G. Cook; R. A. Kuenast; S. B. Pratap; R. C. Thompson; H. D. Yun

1993-01-01

35

Single-Stage Axial Compressor Stator Redesign Investigation.  

National Technical Information Service (NTIS)

The report describes the results of a program to redesign the exit stators of a 2.8:1 pressure ratio supersonic axial compressor, and to fabricate and test the redesigned stators to evaluate the effect of the redesign on the overall stage performance. Thi...

C. Muller

1970-01-01

36

Effects of toothless stator design on dynamic model parameters of permanent magnet generators  

Microsoft Academic Search

The effects of toothless stator design on the dynamic model parameters of permanent magnet (PM) generators are presented. These parameters, which include inductances and induced back EMFs, are determined for a 75 kVA, 208 V, 400 Hz, two-pole, permanent magnet generator. Two particular stator designs, a toothless stator, and a conventional type stator (with iron teeth), are considered. The method

A. A. Arkadan; R. Vyas

1993-01-01

37

On-line stator and rotor resistance estimation for induction motors  

Microsoft Academic Search

A ninth-order estimation algorithm is designed which provides online exponentially convergent estimates of both rotor and stator resistance for induction motors, when persistency of excitation conditions are satisfied and the stator current integrals are bounded, on the basis of rotor speed, stator voltages, and stator current measurements. Rotor flux is also asymptotically recovered. Experimental tests are reported which show that:

Riccardo Marino; Sergei Peresada; Patrizio Tomei

2000-01-01

38

A two-stator MEMS power generator for cardiac pacemakers  

Microsoft Academic Search

The design of a bio-mechanically driven double stator axial flux MEMS power generator for use in cardiac pacemakers has been presented. In the system, an asymmetrical circular rotor embedded with alternate polarity microfabricated NdFeB permanent magnets oscillates around a central shaft due to the motion of the thorax during breathing to induce a voltage across the stator coils. The generator

Jose Martinez-quijada; Sazzadur Chowdhury

2008-01-01

39

Ceramic-to-metal stator vane assembly with braze  

DOEpatents

A stator vane assembly for a gas turbine engine that includes a plurality of circumferentially spaced ceramic vanes, each of which has an inner and outer ceramic shroud, and a ceramic post extending from one of the shrouds, and a metallic platform having a plurality of circumferentially spaced recesses. The posts are inserted into a metallic sleeve and then brazed. The brazed sleeves are then mounted in the recesses. A method for assembling these components to form the stator assembly is also described.

Chase, Donna J. (Scottsdale, AZ); Fang, Ho T. (Scottsdale, AZ); Irwin, Craig W. (Tempe, AZ); Schienle, James L. (Phoenix, AZ)

1995-01-01

40

In-service winding failure of newly installed replacement stator  

Microsoft Academic Search

Installing a new or replacement generator requires careful consideration during installation, offline acceptance testing and increased diligence during initial start-up and operation. After replacing the first of four 132 MVA, 15 kV, 85.7 RPM Allis-Chalmers hydrogenerator stators, Chelan County PUD personnel were confronted with an unexpected distribution of generator stator RTD temperatures during the initial unit start-up. A correlation was

A. Showalter; J. S. Edmonds

1999-01-01

41

The vortex interaction in a propeller/stator flow field  

NASA Technical Reports Server (NTRS)

The vortex interaction encounered in the flow field of a propeller and a stator has been investigated using smoke flow visualization. A stator at angle of attack was used to generate a line vortex which interacted with the helical vortex filaments generated by a propeller. Changes in the relative vortex strengths and vortex rotational directions yielded several distinct vortex structures. Axial flow in the vortex cores is determined to influence the development of the vortex interaction.

Johnston, R. T.; Sullivan, J. P.

1991-01-01

42

Rotor wake/stator interaction noise-predictions versus data  

NASA Astrophysics Data System (ADS)

A rotor wake/stator interaction noise prediction method is presented and evaluated with fan rig and full-scale engine data. The noise prediction method uses a two-dimensional (2D) semi-empirical wake model and an analytical stator response function and noise calculation. The stator response function is a 2D strip theory which is linked to a noise calculation formulated in a constant area annular duct with mean axial flow. Comparisons are made with data from an Advanced Ducted Propeller (ADP) fan rig which is a next-generation turbofan engine design. A calibration of the prediction model is attempted using this rig data. The calibrated model is subsequently utilized to calculate and compare with noise test data from a 4.1-inch diameter fan rig and from a full-scale turbofan engine configuration. The results indicate the method has promise, but that further improvement is desirable.

Topol, D. A.

1990-10-01

43

A planar variable reluctance magnetic micromotor with fully integrated stator and coils  

Microsoft Academic Search

A fully functional electrically excited planar variable reluctance magnetic micromotor has been demonstrated on a silicon wafer. The motor uses a micromachined nickel-iron rotor and a fully integrated stator, in which a toroidal-meander type integrated inductive component is used for flux generations. To reduce the magnetic reluctance in the stator, a modified stator geometry was adopted which removes the yoke

Chong H. Ahn; Yong J. Kim; Mark G. Allen

1993-01-01

44

A direct torque controlled interior permanent magnet synchronous machine drive with a new stator resistance estimator  

Microsoft Academic Search

The stator resistance variation will deteriorate the performance of a direct torque controlled (DTC) drive, and therefore is a significant issue for DTC. In order to solve this issue, a novel stator resistance estimator for an interior permanent magnet synchronous machine (IPMSM) based on stator current has been proposed and evaluated. The advantage of this scheme is that it needs

Lixin Tang; Muhammed F. Rahman

2003-01-01

45

Low-Cost Stator Material M734 Alternators.  

National Technical Information Service (NTIS)

The M734 multioption mortar fuze employs an air-driven alternator to power the fuze electronics and to furnish a mechanical arming signature. The stator of the alternator is fabricated from an expensive high-nickel-content steel, Permalloy, costing $6.00 ...

J. E. Fine

1983-01-01

46

Advancements in partial discharge analysis to diagnose stator winding problems  

Microsoft Academic Search

On-line partial discharge (PD) testing has been used for over 50 years to assess the condition of motor and generator stator winding insulation systems. In the past decade, advanced hardware and software have enabled superior methods of converting the PD data into practical information about the relative condition of the insulation, as well as determining the root causes of any

V. Warren; G. C. Stone; M. Fenger

2000-01-01

47

Aeropropulsion Technology (APT). Task 23 - Stator Seal Cavity Flow Investigation  

NASA Technical Reports Server (NTRS)

The focus of NASA Contract NAS3-25950 Task 23 was to numerically investigate the flow through an axial compressor inner-banded stator seal cavity. The Allison/NASA developed ADPAC code was used to obtain all flow predictions. Flow through a labyrinth stator seal cavity of a high-speed compressor was modeled by coupling the cavity flow path and the main flow path of the compressor. A grid resolution study was performed to guarantee adequate grid spacing was used. Both unsteady rotor-stator-rotor interactions and steady-state isolated blade calculations were performed with and without the seal cavity present. A parameterized seal cavity study of the high-speed stator seal cavity collected a series of solutions for geometric variations. The parameter list included seal tooth gap, cavity depth, wheel speed, radial mismatch of hub flowpath, axial trench gap, hub corner treatments, and land edge treatments. Solution data presented includes radial and pitchwise distributions of flow variables and particle traces describing the flow character.

Heidegger, N. J.; Hall, E. J.; Delaney, R. A.

1996-01-01

48

SQUID measurements for thermal aging of stator windings  

Microsoft Academic Search

Conventional non-destructive diagnostic tests for aging of dielectric insulation on high voltage cables and stator windings are limited to measurements of lumped electrical parameters. Commonly used step voltage tests may lead to breakdown of the insulation and damage to the system. A map of spatial distribution of the electrical properties of the cable may provide the information about the age-related

Yu Pei Ma; John P. Wikswo; Gerald Fitzpatrick

2001-01-01

49

Electromagnetic pump stator frame having power crossover struts  

DOEpatents

A stator frame for an electromagnetic pump includes a casing joined to a hub by a plurality of circumferentially spaced apart struts. At least one electrically insulated power crossover lead extends through the hub, through a crossover one of the struts, and through the casing for carrying electrical current therethrough.

Fanning, Alan W. (San Jose, CA); Olich, Eugene E. (Aptos, CA)

1995-01-01

50

Impact Loading of Compressor Stator Vanes by Hailstone Ingestion.  

National Technical Information Service (NTIS)

Impacts of 1 inch diameter ice bullets onto stator vanes of the first stage of an axial compressor were investigated at an impact velocity of v = 257 m/s. The analytical and experimental simulations of typical hailstone ingestions were performed with spec...

J. Frischbier

1994-01-01

51

Magnetic field in the stator yoke of homopolar inductor alternators  

Microsoft Academic Search

An algorithm is developed for the numerical calculation of the magnetic field in the stator yoke of homopolar inductor alternators with periodic boundary conditions set in terms of the normal flux density vector component on inside and outside surfaces of the yoke. The proposed algorithm is based on the line relaxation algorithm and, unlike other algorithms, features an additional condition

V. V. Apsit; Iu. I. Dikin; D. Ia. Macha

1979-01-01

52

Rotor and stator assembly configured as an aspirating face seal  

NASA Technical Reports Server (NTRS)

A rotor and stator assembly having a rotor and a stator with opposing surfaces defining an air bearing and an air dam of an aspirating face seal. In a first embodiment, the air bearing and the air dam are axially offset. In a second embodiment, the rotor has an axially extending protuberance located radially between the air bearing and the air dam. The axial offset and the protuberance each act to divert the air flow (e.g., compressed gas or combustion gases in a gas turbine or steam in a steam turbine) in a direction transverse to the air flow direction through the air bearing and the air dam, thus isolating the air flows from the air bearing and the air dam which improves seal performance.

Turnquist, Norman Arnold (Inventor); Bagepalli, Bharat Sampathkumaran (Inventor); Reluzco, George (Inventor); Tseng, Wu-Yang (Inventor)

1999-01-01

53

Stator Loading Measurements Behind a Fan With Trailing Edge Blowing  

NASA Technical Reports Server (NTRS)

The problem of aircraft noise pollution around airports has become increasingly important as those areas have become more densely populated. Currently, the removal of older noisier aircraft from operation is reducing noise levels around airports; however, with air traffic projected to increase by about 5% over the next decade the number of commercial aircraft operating in the world is expected to be about 17,700 by the year 2007. To keep noise levels around airports from increasing as a result of traffic increases, it is important to investigate new methods of noise reduction. The objective of this work is to provide a better understanding of the effects that trailing edge blowing has on stator unsteady loading. This is done by presenting flowfield and stator loading data from experiments conducted with and without trailing edge blowing.

Waitz, Ian A.

2000-01-01

54

Aging of stator bars exposed to end arm discharges  

Microsoft Academic Search

Three of the most common types of end arm discharges occurring during normal operation of air-cooled hydro-generators have been simulated in the laboratory. Sections of stator bars have been modified to induce either surface tracking, corona discharges at the semi-conductive paint\\/corona suppressor junction, or bar-to-bar discharges. Two setups of each type of defect were subjected to an aging voltage of

C. Hudon; M. Belec

1996-01-01

55

Analyzing Flow Fields in Axial-Compressor Rotors and Stators  

NASA Technical Reports Server (NTRS)

Computer program, BLADE3D, developed for analysis of inviscid threedimensional flow fields in single blade passage of axial-compressor rotor or stator. Applicable to arbitrary axial-compressor hub, tip, and blade geometries, including blades with part-span dampers. Also used for axial turbines but with lowered resolution of flows about blunt leading and trailing edges. Analysis method valid for subsonic, transonic and supersonic flows, including choked flows.

Thompkins, W. J., Jr.

1984-01-01

56

Development of the stator for a 20-MVA superconducting generator  

SciTech Connect

A detailed component development program is followed in which the critical components necessary to achieve superconducting generators for central power plant applications are discussed. The stator concept is described and illustrated. Its development is described and the armature bar and assembly are illustrated. Future (1981) tests are projected. The overall design of the 20-MVA superconducting generator is summarized in two tables, one of principal dimensions and the other of computed parameters.

Laskaris, T.E.; Keim, T.A.; Rios, P.A.; Schoch, K.F.

1982-01-01

57

Influence of vane sweep on rotor-stator interaction noise  

NASA Technical Reports Server (NTRS)

The influence of vane sweep in rotor-stator interaction noise is investigated. In an analytical approach, the interaction of a convected gust representing the rotor viscous wake, with a cascade of cascade of finite span swept airfoils, representing the stator, is analyzed. The analysis is based on the solution of the exact linearized equations of motion. High frequency convected gusts for which noise generation is concentrated near the leading edge of airfoils is considered. In a preliminary study, the problem of an isolated finite span swept airfoil interacting with a convected gust is analyzed. Results indicate that sweep can substantially reduce the farfield noise levels for a single airfoil. Using the single airfoil model, an approximate solution to the problem of noise radiation from a cascade of finite span swept airfoils interacting with a convected gust is derived. A parametric study of noise generated by gust cascade interaction is carried out to assess the effectiveness of vane sweep in reducing rotor-stator interaction noise. The results show that sweep is beneficial in reducing noise levels. Rotor wake twist or circumferential lean substantially influences the effectiveness of vane sweep. The orientation of vane sweep must be chosen to enhance the natural phase lag caused by wake lean, in which case rather small sweep angles substantially reduce the noise levels.

Envia, Edmane; Kerschen, Edward J.

1990-01-01

58

Reduction of Wake-Stator Interaction Noise Using Passive Porosity  

NASA Technical Reports Server (NTRS)

The present study was conducted to assess the potential of Passive Porosity Technology as a mechanism to reduce interaction noise in turbomachinery by reducing the fluctuating forces acting on the vane surfaces. To do so, a typical fan stator airfoil was subjected to the effects of a transversely moving wake; time histories of the primitive aerodynamic variables, obtained from Computational Fluid Dynamics (CFD) solutions, were then input into an acoustic prediction code. This procedure was performed on the solid airfoil to obtain a baseline, and on a series of porous configurations in order to isolate those that yield maximum noise reductions without compromising the aerodynamic performance of the stator. It was found that communication between regions of high pressure differential - made possible by the use of passive porosity - is necessary to significantly alter the noise radiation pattern of the stator airfoil. In general, noise reductions were obtained for those configurations incorporating passive porosity in the region between x/c is approximately 0.15 on the suction side of the airfoil and x/c is approximately 0.20 on the pressure side. Reductions in overall radiated noise of approximately 1.0 dB were obtained. The noise benefit increased to about 2.5 dB when the effects of loading noise alone were considered.

Tinetti, Ana F.; Kelly, Jeffrey J.; Thomas, Russell H.; Bauer, Steven X. S.

2002-01-01

59

DIAGNOSTICO DEL SISTEMA DE GESTIÓN DE LA CALIDAD SEGÚN LA NC ISO 9001:2008  

Microsoft Academic Search

El presente trabajo se realizó en una entidad dedicada a la prestación de servicios logísticos, el cual posee Certificado el Sistema de Gestión de la Calidad en lo adelante (SGC) según la NC ISO 9001\\/2008. Se trazó como objetivo diagnosticar el Sistema de Gestión de la Calidad, Tomando como guía la NC ISO 9001\\/2008. Para el desarrollo de esta investigación

Arles Segura Maturell

2011-01-01

60

A block-based algorithm for the solution of compressible flows in rotor-stator combinations  

NASA Technical Reports Server (NTRS)

A block-based solution algorithm is developed for the solution of compressible flows in rotor-stator combinations. The method allows concurrent solution of multiple solution blocks in parallel machines. It also allows a time averaged interaction at the stator-rotor interfaces. Numerical results are presented to illustrate the performance of the algorithm. The effect of the interaction between the stator and rotor is evaluated.

Akay, H. U.; Ecer, A.; Beskok, A.

1990-01-01

61

Study of controlled diffusion stator blading. 1. Aerodynamic and mechanical design report  

NASA Technical Reports Server (NTRS)

Pratt & Whitney Aircraft is conducting a test program for NASA in order to demonstrate that a controlled-diffusion stator provides low losses at high loadings and Mach numbers. The technology has shown great promise in wind tunnel tests. Details of the design of the controlled diffusion stator vanes and the multiple-circular-arc rotor blades are presented. The stage, including stator and rotor, was designed to be suitable for the first-stage of an advanced multistage, high-pressure compressor.

Canal, E.; Chisholm, B. C.; Lee, D.; Spear, D. A.

1981-01-01

62

Evidence for two flagellar stators and their role in the motility of Pseudomonas aeruginosa.  

PubMed

Pseudomonas aeruginosa is a ubiquitous bacterium capable of twitching, swimming, and swarming motility. In this study, we present evidence that P. aeruginosa has two flagellar stators, conserved in all pseudomonads as well as some other gram-negative bacteria. Either stator is sufficient for swimming, but both are necessary for swarming motility under most of the conditions tested, suggesting that these two stators may have different roles in these two types of motility. PMID:15629949

Toutain, Christine M; Zegans, Michael E; O'Toole, George A

2005-01-01

63

Upstream-radiated rotor-stator interaction noise in mean swirling flow  

Microsoft Academic Search

A major component of the noise in modern aeroengines is rotor-stator interaction noise generated when the wake from the rotating fan impinges on a stator row downstream. An analytically based model for the prediction of upstream-radiated rotor-stator interaction noise is described, and includes the important effect of mean swirling flow on both the rotor wake evolution and the acoustic response.

A. J. Cooper; N. Peake

2005-01-01

64

Industrial stator vane with sequential impingement cooling inserts  

DOEpatents

A turbine stator vane for an industrial engine, the vane having two impingement cooling inserts that produce a series of impingement cooling from the pressure side to the suction side of the vane walls. Each insert includes a spar with a row of alternating impingement cooling channels and return air channels extending in a radial direction. Impingement cooling plates cover the two sides of the insert and having rows of impingement cooling holes aligned with the impingement cooling channels and return air openings aligned with the return air channel.

Jones, Russell B; Fedock, John A; Goebel, Gloria E; Krueger, Judson J; Rawlings, Christopher K; Memmen, Robert L

2013-08-06

65

Rotor-stator interaction in a diffuser pump  

NASA Technical Reports Server (NTRS)

Steady and unsteady pressure measurements were obtained on the diffuser vanes and the shroud wall of vaned and vaneless diffuser pumps in order to investigate the rotor-stator interaction. It is shown that the magnitude of the fluctuating lift is greater than the steady lift, and that the pressure fluctuations are larger on the suction side than on the pressure side. Pressure fluctuations near the shroud were much smaller than those near the hub across the span of the vane. Pressure fluctuations on the shroud wall itself were found to be larger for the vaned diffuser than for the vaneless diffuser.

Acosta, A. J.; Brennen, C. E.; Caughey, T. K.; Arndt, N.

1988-01-01

66

Modelling and Analysis of Dual-Stator Induction Motors  

NASA Astrophysics Data System (ADS)

In this paper, the analysis and the modelling of a Dual-Stator Induction Motor (DSIM) are presented. In particular, the effects of the shift angle between its three-phase windings are studied. A complex steady state model is first established in order to analyse its harmonic behavior when it is supplied by a non-sinusoidal voltage source. Then, a new transformation matrix is proposed to develop a suitable dynamic model. In both cases, the study is made using an arbitrary shift angle. Simulation results of its PWM control are also presented and compared in order to confirm our theoretical observations.

Razik, Hubert; Rezzoug, Abderrezak; Hadiouche, Djafar

67

Stator fault analysis based on wavelet technique for wind turbines equipped with DFIG  

Microsoft Academic Search

The paper introduces a monitoring and diagnostic technique for the detection of incipient stator electrical faults in doubly fed induction generators (DFIGs) for wind power systems. Depending on wind speed, the induction machine operates continuously in non stationary conditions. In this context, traditional Fourier Analysis fails to discriminate between healthy and abnormal stator operating conditions. To overcome this limitation a

Y. Gritli; A. Stefani; F. Filippetti; A. Chatti

2009-01-01

68

Use of ramp test to expedite return to service of damaged stator winding  

Microsoft Academic Search

The fracture of a clamping finger resulted in major damage to the stator core and winding of a 13.8 kV 120 MVA hydro generator. Immediately following the fault the fire suppression water deluge system operated for a period of time. The polyester bonded mica insulation system of this stator winding is known to be vulnerable to tape separations in the

W. McDermid; R. Gamblin

2007-01-01

69

Simulation of a High Temperature Superconducting Synchronous Machine with Stator Core Saturation  

Microsoft Academic Search

Saturation effects in salient pole synchronous machines are generally modelled by assuming that the saturation effect is primarily limited to the field pole. However, a superconducting machine does not possess field pole saturation since it is free of iron. The stator, however, remains surrounded by an iron shell so that saturation of the stator core is possible. This paper addresses

T. A. Lipo

70

Voltage stresses on stator windings of induction motors driven by IGBT PWM inverters  

Microsoft Academic Search

In the IGBT PWM inverter, insulation breakdown and irregular voltage distribution on stator winding due to high rate of voltage rise (dv\\/dt) caused by high-frequency switching and impedance mismatches between inverter and motor have been treated as the main consideration. This paper describes the distribution characteristics of switching the surge voltage in the stator windings of an induction motor driven

Don-Ha Hwang; Ki-Chang Lee; Yong-Joo Kim; Sung-Woo Bae; Dong-Hee Kim; Chae-Gyun Ro

2003-01-01

71

Application of partial discharge testing to motor and generator stator winding maintenance  

Microsoft Academic Search

Deterioration of stator winding insulation continues to be one of the predominant causes of large motor and generator failures. Over the past several years, practical methods have been developed for measuring the partial discharge activity in the high voltage insulation of stator windings, since partial discharges are a symptom of most of the insulation failure mechanisms in motors and generators

Greg C. Stone; Howard G. Sedding; Michael J. Costello

1996-01-01

72

Superconducting electromechanical rotating device having a liquid-cooled, potted, one layer stator winding  

DOEpatents

A superconducting electromechanical rotating (SER) device, such as a synchronous AC motor, includes a superconducting field winding and a one-layer stator winding that may be water-cooled. The stator winding is potted to a support such as the inner radial surface of a support structure and, accordingly, lacks hangers or other mechanical fasteners that otherwise would complicate stator assembly and require the provision of an unnecessarily large gap between adjacent stator coil sections. The one-layer winding topology, resulting in the number of coils being equal to half the number of slots or other mounting locations on the support structure, allows one to minimize or eliminate the gap between the inner radial ends of adjacent straight sections of the stator coilswhile maintaining the gap between the coil knuckles equal to at least the coil width, providing sufficient room for electrical and cooling element configurations and connections. The stator winding may be potted to the support structure or other support, for example, by a one-step VPI process relying on saturation of an absorbent material to fill large gaps in the stator winding or by a two-step process in which small gaps are first filled via a VPI or similar operation and larger gaps are then filled via an operation that utilizes the stator as a portion of an on-site mold.

Dombrovski, Viatcheslav V. (Willoughby Hills, OH); Driscoll, David I. (South Euclid, OH); Shovkhet, Boris A. (Beachwood, OH)

2001-01-01

73

Variations in the capacitance of delaminated HV stator insulation due to electrostatically generated forces  

Microsoft Academic Search

Expressions that describe the variations in the capacitance and tan delta in delaminated stator winding insulation due to electrostatic forces have been obtained. Experimental results obtained on a stator whose insulation was seen to have delaminated dielectric support the suggested theory. Measurements performed at a relatively low voltage could be used to determine the extent of delamination and possibly the

C. Pinto

1991-01-01

74

Sensorless operation of permanent magnet AC (PMAC) motors with modified stator windings  

Microsoft Academic Search

A sensorless field oriented control scheme for permanent magnet AC (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however, is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for

Khwaja M. Rahman; Hamid A. Toliyat

1996-01-01

75

Tuning the stator resistance of induction motors using artificial neural network  

SciTech Connect

Tuning the stator resistance of induction motors is very important, especially when it is used to implement direct torque control (DTC) in which the stator resistance is a main parameter. In this paper, an artificial network (ANN) is used to accomplish tuning of the stator resistance of an induction motor. The parallel recursive prediction error and backpropagation training algorithms were used in training the neural network for the simulation and experimental results, respectively. The neural network used to tune the stator resistance was trained on-line, making the DTC strategy more robust and accurate. Simulation results are presented for three different neural-network configurations showing the efficiency of the tuning process. Experimental results were obtained for the one of the three neural-network configuration. Both simulation and experimental results showed that the ANN have tuned the stator resistance in the controller to track actual resistance of the machine.

Cabrera, L.A.; Elbuluk, M.E.; Husain, I. [Univ. of Akron, OH (United States). Dept. of Electrical Engineering] [Univ. of Akron, OH (United States). Dept. of Electrical Engineering

1997-09-01

76

Incompressible lifting-surface aerodynamics for a rotor-stator combination  

NASA Technical Reports Server (NTRS)

Current literature on the three dimensional flow through compressor cascades deals with a row of rotor blades in isolation. Since the distance between the rotor and stator is usually 10 to 20 percent of the blade chord, the aerodynamic interference between them has to be considered for a proper evaluation of the aerothermodynamic performance of the stage. A unified approach to the aerodynamics of the incompressible flow through a stage is presented that uses the lifting surface theory for a compressor cascade of arbitrary camber and thickness distribution. The effects of rotor stator interference are represented as a linear function of the rotor and stator flows separately. The loading distribution on the rotor and stator flows separately. The loading distribution on the rotor and stator blades and the interference factor are determined concurrently through a matrix iteration process.

Ramachandra, S. M.

1984-01-01

77

Experimental investigation of rotor wake/stator interaction noise generation by acoustic mode measurements  

NASA Astrophysics Data System (ADS)

The rotor wake/stator interaction noise generation was investigated using acoustic measurements in a low-speed wind tunnel, downstream of a rotor/stator combination; some acoustic measurements were also carried out in the intake duct of the wind tunnel model and outside the model. The blade passing frequency harmonics were found to be dominated by the regular rotor/stator interaction modes. In addition, cut-off rotor/stator interaction modes were observed; the origin of these is considered to be in the highly nonuniform flow downstream of the rotor/stator. An additinal noise source occurred due to the lock-in of rotor vortex shedding and acoustic spinning modes.

Zandbergen, T.

1989-04-01

78

Finite-element analysis of the rotor\\/stator contact in a ring-type ultrasonic motor  

Microsoft Academic Search

A way to understand mechanical characteristics of an ultrasonic motor is presented. First, the vibration mode of a stator is calculated using a finite-element method (FEM) code. The path of the elliptic motion of the stator's teeth is obtained. The computed vibration mode at the surface of the stator is compared with that measured by an electrooptical displacement transducer. Next,

Takashi Maeno; Takayuki Tsukimoto; Akira Miyake

1992-01-01

79

The control of stator flux and torque in the surface permanent magnet synchronous motor direct torque control system  

Microsoft Academic Search

This paper discusses the control of stator flux and torque in the surface permanent magnet synchronous motor (SPMSM) direct torque control (DTC) system. The study shows the angle between stator flux vector and the applying voltage vector determines the dynamic behavior of stator flux and the angle between rotor flux vector and the applying voltage vector determines the dynamic behavior

Yaohua Li; Weiguo Liu; Zhaoyang Fu; Dieter Gerling

2009-01-01

80

Turbine stator vane segment having internal cooling circuits  

DOEpatents

A turbine stator vane includes outer and inner walls each having outer and inner chambers and a vane extending between the outer and inner walls. The vane includes first, second, third, fourth and fifth cavities for flowing a cooling medium. The cooling medium enters the outer chamber of the outer wall, flows through an impingement plate for impingement cooling of the outer band wall defining in part the hot gas path and through openings in the first, second and fourth cavities for flow radially inwardly, cooling the vane. The spent cooling medium flows into the inner wall and inner chamber for flow through an impingement plate radially outwardly to cool the inner wall. The spent cooling medium flows through the third cavity for egress from the turbine vane segment from the outer wall. The first, second or third cavities contain inserts having impingement openings for impingement cooling of the vane walls. The fifth cavity provides air cooling for the trailing edge.

Jones, Raymond Joseph (Oxford, MA); Burns, James Lee (Schenectady, NY); Bojappa, Parvangada Ganapathy (Simpsonville, SC); Jones, Schotsch Margaret (Greer, SC)

2003-01-01

81

Acoustic Benefits of Stator Sweep and Lean for a High Tip Speed Fan  

NASA Technical Reports Server (NTRS)

A model high-speed fan stage was acoustically tested in the NASA Glenn 9- by 15-Foot Low Speed Wind Tunnel at takeoff/approach flight conditions. The fan was designed for a corrected rotor tip speed of 442 m/s (1450 ft/s), and had a powered core, or booster stage, giving the model a nominal bypass ratio of 5. The model also had a simulated engine pylon and nozzle bifurcation contained within the bypass duct. The fan was tested with three stator sets to evaluate acoustic benefits associated with a swept and leaned stator and with a swept integral vane/frame stator which incorporated some of the swept and leaned features as well as eliminated some of the downstream support structure. The baseline fan with the wide chord rotor and baseline stator approximated a current GEAE CF6 engine. A flyover effective perceived noise level (EPNL) code was used to generate relative EPNL values for the various configurations. Flyover effective perceived noise levels (EPNL) were computed from the model data to help project noise benefits. A tone removal study was also performed. The swept and leaned stator showed a 3 EPNdB reduction at lower fan speeds relative to the baseline stator; while the swept integral vane/frame stator showed lowest noise levels at intermediate fan speeds. Removal of the bypass blade passage frequency rotor tone (BPF) showed a 4 EPNdB reduction for the baseline and swept and leaned stators, and a 6 EPNdB reduction for the swept integral vane/ frame stator. Therefore, selective tone removal techniques such as active noise control and/or tuned liner could be particularly effective in reducing noise levels for certain fan speeds.

Woodward, Richard P.; Gazzaniga, John A.; Bartos, Linda J.; Hughes, Christopher E.

2002-01-01

82

The influence of shrouded stator cavity flows on multistage compressor performance  

SciTech Connect

Experiments were performed on a low-speed multistage axial-flow compressor to assess the effects of shrouded stator cavity flows on aerodynamic performance. Five configurations, which involved systematic changes in seal-tooth leakage rates and/or elimination of the shrouded stator cavities, were tested. Rig data indicate increasing seal-tooth leakage substantially degraded compressor performance. For every 1 percent increase in seal-tooth clearance-to-span ratio, the decrease in pressure rise was 3 percent and the reduction in efficiency was 1 point. These observed performance penalties are comparable to those commonly reported for rotor and cantilevered stator tip clearance variations. The performance degradation observed with increased leakage was brought about in two distinct ways. First, increasing seal-tooth leakage directly spoiled the near-hub performance of the stator row in which leakage occurred. Second, the altered stator exit flow conditions, caused by increased leakage, impaired the performance of the next downstream stage by decreasing the work input of the rotor and increasing total pressure loss of the stator. These trends caused the performance of downstream stages to deteriorate progressively. Numerical simulations of the test rig stator flow field were also conducted to help resolve important fluid mechanic details associated with the interaction between the primary and cavity flows. Simulation results show that fluid originating in the upstream cavity collected on the stator suction surface when the cavity tangential momentum was low and on the pressure side when it was high. The convection of cavity fluid to the suction surface was a mechanism that reduced stator performance when leakage increased.

Wellborn, S.R. [Rolls-Royce Allison, Indianapolis, IN (United States); Okiishi, T.H. [Iowa State Univ., Ames, IA (United States)

1999-07-01

83

Performance evaluations of 50 MVA airgap winding stator for superconducting generator  

SciTech Connect

This paper describes structural features of a trial-manufactured airgap winding stator for a 50 MVA superconducting generator and results of various characteristic tests. The stator has an improved winding section, strengthened against electromagnetic force and smaller sized, due to use of a four-layer water cooled helical airgap armature winding. Peculiarities as to the flux distribution and airgap winding electromagnetic force of the generator during operation were clarified, based on a three-dimensional magnetic field analysis. The structure of this airgap winding stator is sufficiently durable for use in the 50 MVA superconducting generator.

Takahashi, M.; Watanabe, M.; Takahashi, N.; Kitamura, M.; Maki, N.; Ooi, M.

1989-06-01

84

Specific features relating to the motion of a rotor with rubbing against the stator  

NASA Astrophysics Data System (ADS)

Specific features relating to the motion of a rotor with rubbing against the stator and the rolling of a rotor over the stator are considered. Conditions under which rolling of the rotor over the stator occurs and the kinematic and force characteristics of this phenomenon are investigated. Simple analytical solutions are obtained for a model assuming that an absolutely rigid rotor and an absolutely rigid stator come in absolutely inelastic contact with each other, which allow one to get a clear idea about the roll-over phenomenon. An attempt is made on the basis of the proposed model to understand some striking features of the accident that occurred in the 300 MW power unit at the Kashira district power station in 2002.

Kostyuk, A. G.; Shatokhin, V. F.; Volokhovskaya, O. A.

2013-09-01

85

Ac hysteresis loop measurement of stator-tooth in induction motor  

SciTech Connect

The properties of ac hysteresis loop of a stator tooth in a 5 hp induction motor was measured and analyzed. The load increase on the motor decreased magnetic induction, however increase the minor hysteresis loops in the high induction region. This effect caused increase in the core loss. Depending on condition of the motor, the core loss of the stator tooth can be 50% greater than the core loss under sinusoidal magnetic induction waveform.

Son, D.

1999-09-01

86

Numerical Simulation of Flow in Hub-Gap of Axial Stator Blades  

NASA Astrophysics Data System (ADS)

In this paper there is described the numerical simulation of flow in the axial stator blade cascade with the radial gap between the hub and the stator blades. Influence of the gap size on distributions of the pressure, the Mach number, the kinetic energy losses, and the flow angle along the span is presented. There is also studied the possibility of modifying the shape of the hub to restrict the flow rate through the radial gap.

Straka, Petr

2014-03-01

87

A novel stand-alone dual stator-winding induction generator with static excitation regulation  

Microsoft Academic Search

On the basis of the new idea of electric power integration, a novel stand-alone dual stator-winding induction generator (DWIG) system is built. In this generator, there are two sets of windings to be embedded in the stator slots. One, referred to as the 12-phase power winding, supplies power to the dc load via a 12-phase bridge rectifier, and the other,

Dong Wang; Weiming Ma; Fei Xiao; Botao Zhang; Dezhi Liu; An Hu

2005-01-01

88

PWM-VSI inverter-assisted stand-alone dual stator winding induction generator  

Microsoft Academic Search

This paper presents a novel usage of a dual stator winding three-phase induction machine as a stand-alone generator with both controlled output load voltage magnitude and frequency. This generator, with both three-phase power and control windings housed in the stator structure, has the load connected to the power winding and a three-phase pulsewidth modulation (PWM) voltage-source inverter sourcing the control

Olorunfemi Ojo; I. E. Davidson

2000-01-01

89

PWM-VSI inverter assisted stand-alone dual stator winding induction generator  

Microsoft Academic Search

This paper presents a novel usage of a dual stator winding, three-phase induction machine as a stand-alone generator with both controlled output load voltage magnitude and frequency. This generator, with both three-phase power and control windings housed in the stator structure, has the load connected to the power winding and a three-phase PWM voltage source inverter sourcing the control winding.

Olorunfemi Ojo; Innocent E. Davidson

1999-01-01

90

Mathematical model of the two orthogonal three-phase windings stator generator  

Microsoft Academic Search

This paper considers the induction generator having two similar separate three-phase stator windings, wound for the same number of poles and a standard squirrel rotor (IG2). Here is given the mathematical model of such induction machine, which is based on our previous results, namely, the two separate stator windings must be space-displaced at 90 electrical degrees, one from the other

Radu Boraci; Marius Babescu; Nicolae Budisan; A. R. Boraci

2009-01-01

91

Design Selection and Analysis of a Swept and Leaned Stator Concept  

NASA Technical Reports Server (NTRS)

This report describes a theoretical design and analysis study of the benefits of vane sweep and lean for reducing rotor- stator interaction tone noise. It is shown that the kinematic relationship between the rotor wakes and stator vanes is the principal factor in determining the achievable noise reductions. Vane sweep and lean control rotor wake skewing as seen by the stator vanes and hence influence the number of wake intersections per vane. An increase in the number of intersections reduces noise levels. Hence, to reduce rotor-stator noise, van sweep and lean must be chosen in such a way as to increase wake intersections per vane. A simple design rule is thus proposed which requires a sweep configuration that puts the vane tip downstream of its root and a vane lean that is in the direction of the rotor rotation. A detailed comparison of the predicted and measured noise reductions for a swept and leaned stator is then carried out. Overall, these comparisons show that the predicted benefits of a swept and leaned stator are in good agreement, qualitative as well as quantitative, with the measured reductions for the fan speeds relevant to noise certification procedure. Furthermore, the results also demonstrate the validity of design criterion and the theoretical tools used in this study.

Envia, Edmane; Nallasamy, M.

1998-01-01

92

Rotor-stator molecular crystals of fullerenes with cubane  

NASA Astrophysics Data System (ADS)

Cubane(C8H8) and fullerene(C60) are famous cage molecules with shapes of platonic or archimedean solids. Their remarkable chemical and solid-state properties have induced great scientific interest. Both materials form polymorphic crystals of molecules with variable orientational ordering. The idea of intercalating fullerene with cubane was raised several years ago but no attempts at preparation have been reported. Here we show that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane. Static cubane occupies the octahedral voids of the face-centred-cubic structures and acts as a bearing between the rotating fullerene molecules. The smooth contact of the rotor and stator molecules decreases significantly the temperature of orientational ordering. These materials have great topochemical importance: at elevated temperatures they transform to high-stability covalent derivatives although preserving their crystalline appearance. The size-dependent molecular recognition promises selective formation of related structures with higher fullerenes and/or substituted cubanes.

Pekker, Sándor; Kováts, Éva; Oszlányi, Gábor; Bényei, Gyula; Klupp, Gyöngyi; Bortel, Gábor; Jalsovszky, István; Jakab, Emma; Borondics, Ferenc; Kamarás, Katalin; Bokor, Mónika; Kriza, György; Tompa, Kálmán; Faigel, Gyula

2005-10-01

93

Rotor-stator molecular crystals of fullerenes with cubane.  

PubMed

Cubane (C8H8) and fullerene (C60) are famous cage molecules with shapes of platonic or archimedean solids. Their remarkable chemical and solid-state properties have induced great scientific interest. Both materials form polymorphic crystals of molecules with variable orientational ordering. The idea of intercalating fullerene with cubane was raised several years ago but no attempts at preparation have been reported. Here we show that C60 and similarly C70 form high-symmetry molecular crystals with cubane owing to topological molecular recognition between the convex surface of fullerenes and the concave cubane. Static cubane occupies the octahedral voids of the face-centred-cubic structures and acts as a bearing between the rotating fullerene molecules. The smooth contact of the rotor and stator molecules decreases significantly the temperature of orientational ordering. These materials have great topochemical importance: at elevated temperatures they transform to high-stability covalent derivatives although preserving their crystalline appearance. The size-dependent molecular recognition promises selective formation of related structures with higher fullerenes and/or substituted cubanes. PMID:16142242

Pekker, Sándor; Kováts, Eva; Oszlányi, Gábor; Bényei, Gyula; Klupp, Gyöngyi; Bortel, Gábor; Jalsovszky, István; Jakab, Emma; Borondics, Ferenc; Kamarás, Katalin; Bokor, Mónika; Kriza, György; Tompa, Kálmán; Faigel, Gyula

2005-10-01

94

Analytical Derivation of a Coupled-Circuit Model of a Claw-Pole Alternator with Concentrated Stator Winding  

Microsoft Academic Search

A lumped-parameter coupled-circuit model of a claw-pole altemator is derived. To derive the model, analytical techniques are used to define a three-dimensional Fourier-series representation of the airgap flux density. Included in the series expansion are the harmonics introduced by rotor saliency, concentrated stator windings, and stator slots. From the alrgap flux density waveform, relatively simple closed-form expressions for the stator

H. Bai; S. Pekarek; J. Techenor; W. Eversman; D. Buening; G. Holbrook; M. Hull; R. Krefta; S. Shields

2001-01-01

95

A new stator-flux orientation strategy for flux-switching permanent magnet motor based on current-hysteresis control  

Microsoft Academic Search

A stator-flux orientation strategy based on current hysteresis for the flux-switching permanent magnet (FSPM) motor is proposed, in which the stator-PM FSPM motor is considered as a conventional rotor-PM surface-mounted motor and an equivalent rotor-orientated dq-axes synchronous reference frame is built although there are actually no rotary magnetic motive force produced by the stator magnets in the FSPM motor. Based

Wei Hua; Ming Cheng; Wei Lu; Hongyun Jia

2009-01-01

96

Rotor Wake/Stator Interaction Noise Prediction Code Technical Documentation and User's Manual  

NASA Technical Reports Server (NTRS)

This report documents the improvements and enhancements made by Pratt & Whitney to two NASA programs which together will calculate noise from a rotor wake/stator interaction. The code is a combination of subroutines from two NASA programs with many new features added by Pratt & Whitney. To do a calculation V072 first uses a semi-empirical wake prediction to calculate the rotor wake characteristics at the stator leading edge. Results from the wake model are then automatically input into a rotor wake/stator interaction analytical noise prediction routine which calculates inlet aft sound power levels for the blade-passage-frequency tones and their harmonics, along with the complex radial mode amplitudes. The code allows for a noise calculation to be performed for a compressor rotor wake/stator interaction, a fan wake/FEGV interaction, or a fan wake/core stator interaction. This report is split into two parts, the first part discusses the technical documentation of the program as improved by Pratt & Whitney. The second part is a user's manual which describes how input files are created and how the code is run.

Topol, David A.; Mathews, Douglas C.

2010-01-01

97

Effect of endwall cooling on secondary flows in turbine stator vanes  

NASA Technical Reports Server (NTRS)

The effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a core turbine stator vane was determined. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects were obtained. Two endwall cooling configurations were tested. In the first configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In the second configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented towards the vane pressure stator. In both cases the stator vanes were solid and uncooled so that the effect of endwall cooling was obtained directly. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows at the design, mean-radius, critical velocity ratio of 0.778. Changes in the total-pressure contours downstream of the vanes were used to obtain the effect of endwall cooling on the secondary flows in the stator.

Goldman, L. J.; Mclallin, K. L.

1977-01-01

98

Study of Thrust Ripple Suppression Using Interpoles of Intermittent Stator Permanent Magnet Linear Synchronous Motor  

NASA Astrophysics Data System (ADS)

For short and intermediate distance conveyance using intermittent stator permanent magnet linear synchronous motor (ISPM-LSM), a linear synchronous motor with a short stator (armature) is desirable for increasing the stroke length. A PM-LSM with four poles and three teeth has previously been proposed. However, in the case of few teeth, the generated thrust at the outlet edge decreases and a ripple is produced for the generated thrust. In addition, the generated thrust is affected by the cogging force. This paper discusses the use of an interpole at the stator outlet edge and a method to decrease the thrust ripple. Moreover, a method to decrease the cogging force is also presented.

Suzuki, Kenji; Ishikawa, Atsushi; Dohmeki, Hideo

99

Modal decomposition for the analysis of the rotor-stator interactions in multistage compressors  

NASA Astrophysics Data System (ADS)

A modal analysis method of the rotor-stator interactions in multistage compressors has been developed by LMFA. This method, based on a double modal decomposition of the flow over space and time, has been applied to numerical and experimental results of the high-speed 3½-stage compressor CREATE based at LMFA, Lyon-France. It reveals the presence of a very strong rotor-stator interaction which completely drives the flow at casing behind all the rotors. This modal analysis method applied to an unsteady RANS simulation permits to calculate the energy of the rotor-stator interactions and to plot energetic meridian maps to explain experimental results and to analyze the interaction in the whole machine.

Courtiade, N.; Ottavy, X.; Gourdain, N.

2012-06-01

100

An experimental and computational investigation on the effects of stator leakage flow on compressor performance  

NASA Astrophysics Data System (ADS)

Engineers are relying more on computational predictions to aid in the design of multistage compressors. As compressor designs advance to more sophisticated geometries with higher loadings, the predictive tools must be able to capture the effects on secondary flows, those flows not associated with the main compressor through flow. In the rear stages of a compressor where aspect ratios are low, secondary flows associated with endwall boundary layers and shrouded stator leakage flow must be understood. The objective of this research was to investigate the effects of stator leakage flow on compressor performance. All experimental research was conducted at the Purdue 3-Stage Axial Compressor Research Facility. The axial compressor is a scaled-up representation of the rear stages of a high pressure compressor with engine representative Mach numbers and Reynolds numbers. Computational research was conducted using a steady RANS CFD code with multiple meshes to investigate the sensitivity of computational modeling to stator leakage cavities. Facility specific boundary conditions were acquired experimentally and applied to the computational models. Detailed total pressure and total temperature measurements indicate that the inlet of the compressor is circumferentially uniform allowing for an axisymmetric boundary condition to be applied to both experimental and computational research. The shrouded stator cavity in the third stage of the compressor is open to ambient conditions. Mass flow rate through this cavity is measured using an orifice flow meter, and the cavity can be plugged to prevent any leakage flow. Static pressure measurements were acquired at the exit of the stator 3 cavity so that the leakage flow could be simulated and compared with experimental data. Radial total pressure profiles predicted by the different numerical models are compared with experimental profiles with the cavity open and plugged. The predicted compressor performance at high flow conditions was strongly dependent upon the particular leakage flow model employed. Physically meshing the stator cavities yielded the best comparison of overall performance predictions and radial profiles to experimental data near design loading. Since plugging the stator 3 cavity yielded only small changes in the radial total pressure profile, experimental and computational data suggest the leakage flow through the stator 3 cavity on the Purdue 3-Stage Axial Compressor has a relatively negligible impact on overall compressor and stage-by-stage performance.

Ball, Patrick Ryan

101

3D analysis and calculation of stator temperature field of hydrogenerator in the case of sudden short circuit  

Microsoft Academic Search

Sudden short circuit is a serious transient process though it is short in time. In this paper, 3D transient equations of heat conduction as well as its equivalent functional equation are presented. Short circuit current of stator is performed. Sudden short current and heat of the stator are analyzed and calculated. Base on the construction symmetry of ventilating system in

Fan Yadong; Wen Xishan; Xu Shaohua; Deng Wei

2006-01-01

102

Stator winding fault diagnosis in three-phase synchronous and asynchronous motors, by the extended Park's vector approach  

Microsoft Academic Search

This paper describes the use of the extended Park's vector approach (EPVA) for diagnosing the occurrence of stator winding faults in operating three-phase synchronous and asynchronous motors. The major theoretical principles related with the EPVA are presented and it is shown how stator winding faults can be effectively diagnosed by the use of this noninvasive approach. Experimental results, obtained in

S. M. A. Cruz; A. J. Marques Cardoso

2000-01-01

103

Detection of stator short circuit faults in three-phase induction motors using motor current zero crossing instants  

Microsoft Academic Search

Stator faults typically have a significant share amongst the common type of faults in industrial three-phase induction (asynchronous) motors. This paper presents a motor current signature analysis (MCSA)-based diagnostics of the stator winding short circuit fault. This type of fault happens due to the destruction of the turn insulation, and can be very detrimental causing motor shutdown. Instead of traditional

Abhisek Ukil; Shuo Chen; Andrea Andenna

2011-01-01

104

Effect of toothless stator design on the dynamic performance characteristics of high speed permanent magnet generator-load systems  

Microsoft Academic Search

The results of a study on the effect of toothless stator design on the dynamic performance characteristics of high speed permanent magnet generator-load systems are presented. This study is based on the use of magnetic field solutions and state space models which account for saturation due to magnetic material nonlinearities and space harmonics due to machine geometry. Two particular stator

R. Vyas; A. A. Arkadan

1994-01-01

105

Cause and analysis of stator and rotor failures in three-phase squirrel-cage induction motors  

Microsoft Academic Search

The squirrel cage induction motor has limitations, which, if exceeded, will result in premature failure of the stator or rotor. The authors identify the various causes of stator and rotor failures. A specific methodology is proposed to facilitate an accurate analysis of these failures. Failures of the bearings and lubrication systems are excluded

Austin H. Bonnett; George C. Soukup

1992-01-01

106

Identification of rotor position and speed of standard induction motors at low speed including zero stator frequency  

Microsoft Academic Search

The total leakage inductance as seen from the stator windings of standard induction motors varies with the rotor position angle. The effect is exploited to extract the rotor position, and speed, from measured stator voltages. The extraction algorithm is incorporated based on a modification of the pulsewidth modulator. Experimental results demonstrate accurate position measurement at high resolution and high bandwidth

Joachim Holtz; Jinsheng Jiang; Hangwen Pan

1997-01-01

107

A Reconfigurable Motor for Experimental Emulation of Stator Winding Interturn and Broken Bar Faults in Polyphase Induction Machines  

Microsoft Academic Search

The benefits and drawbacks of a 5-hp reconfigurable induction motor, which was designed for experimental emulation of stator winding interturn and broken rotor bar faults, are presented in this paper. It was perceived that this motor had the potential of quick and easy reconfiguration to produce the desired stator and rotor faults in a variety of different fault combinations. Hence,

Chia-Chou Yeh; Gennadi Y. Sizov; Ahmed Sayed-Ahmed; Nabeel A. O. Demerdash; Richard J. Povinelli; Edwin E. Yaz; Dan M. Ionel

2008-01-01

108

System and method for monitoring and controlling stator winding temperature in a de-energized AC motor  

DOEpatents

A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

Lu, Bin (Kenosha, WI); Luebke, Charles John (Sussex, WI); Habetler, Thomas G. (Snellville, GA); Zhang, Pinjia (Atlanta, GA); Becker, Scott K. (Oak Creek, WI)

2011-12-27

109

Effects of blade-vane ratio and rotor-stator spacing of fan noise with forward velocity  

NASA Technical Reports Server (NTRS)

A research fan stage was acoustically tested in an anechoic wind tunnel with a 41 m/sec tunnel flow. Two stator vane numbers giving cut-on and cut-off conditions were tested at three rotor-stator spacings ranging from about 0.5 to 2.0 rotor chords. These two stators were designed for similar aerodynamic performance. Hot film anemometer turbulence measurements were made at the leading edge of the stator for each spacing. The cut-off criterion strongly controlled the fundamental tone level at all spacings. The trends with spacing of the wake defect upwash component at the stator tip showed good agreement with the corresponding cut-on acoustic tone levels.

Woodward, R. P.; Glaser, F. W.

1981-01-01

110

A new stator-flux orientation strategy for flux-switching permanent magnet motor based on current-hysteresis control  

NASA Astrophysics Data System (ADS)

A stator-flux orientation strategy based on current hysteresis for the flux-switching permanent magnet (FSPM) motor is proposed, in which the stator-PM FSPM motor is considered as a conventional rotor-PM surface-mounted motor and an equivalent rotor-orientated dq-axes synchronous reference frame is built although there are actually no rotary magnetic motive force produced by the stator magnets in the FSPM motor. Based on the proposed model, a vector-control strategy with current hysteresis for the FSPM motor drive is investigated and implemented on a dSPACE-based platform, and both the simulated and experimental results validate the effectiveness. It should be emphasized that the proposed stator-flux orientation strategy can be applied to other stator-PM machines (including doubly salient and flux-reversal PM machines) and other control methods (including space-vector pulsed-width-modification and direct torque control).

Hua, Wei; Cheng, Ming; Lu, Wei; Jia, Hongyun

2009-04-01

111

Cold-air investigation of a turbine for high temperature-engine application. 5: Two-stage turbine performance as affected by variable stator area  

NASA Technical Reports Server (NTRS)

The stator areas of the design two-stage turbine were both decreased and increased by nominally 30 percent, and the performances of the two turbines are compared with that of the design stator area turbine. Turbine efficiency decreased with stator area changes. Closing the stator area resulted in the more severe efficiency loss. The decrease in efficiency for both turbines is attributable to rotor incidence, off-design blade-surface velocities, and adverse reaction changes across the blade rows.

Behning, F. P.; Schum, H. J.; Szanca, E. M.

1974-01-01

112

Nonlinear torque and stator flux controller for induction motor drive based on adaptive input–output feedback linearization and sliding mode control  

Microsoft Academic Search

This paper describes a nonlinear torque and stator flux controller for three phase induction motor (IM) drives on the basis of a space vector modulation (SVM) scheme. Using the IM fifth order model in a fixed “ab” axis reference frame with stator currents (isa ,isb) and stator fluxes (?sa,?sb) as state variables, a sliding mode (SM) torque and flux controller

R. Yazdanpanah; J. Soltani; G. R. Arab Markadeh

2008-01-01

113

High gain observer based on-line rotor and stator resistances estimation for IMs  

Microsoft Academic Search

One of the main challenging issues in induction motor drives is the lack of knowledge about the actual values of some critical parameters, such as rotor and stator resistances which are subject to large variations during operation. Such problem is difficult to resolve due to the strong interconnection between states and parameters in the nonlinear motor model, besides the unavailability

S. Hadj Saïd; M. F. Mimouni; F. M’Sahli; M. Farza

2011-01-01

114

High gain observer based on-line rotor and stator resistances estimation for IMs  

Microsoft Academic Search

One of the main challenging issues in induction motor drives is the lack of knowledge about the actual values of some critical parameters, such as rotor and stator resistances which are subject to large variations during operation. Such problem is difficult to resolve due to the strong interconnection between states and parameters in the nonlinear motor model, besides the unavailability

S. H. Sai?d; F. Mimouni; F. M'Sahli; M. Farza

2010-01-01

115

Direct torque control of induction machines with constant switching frequency and improved stator flux estimation  

Microsoft Academic Search

Direct torque control (DTC) of induction machines is known to have a simple control structure yet has comparable performance to that of the field oriented control (FOC). To maintain this simple control structure while at the same time improving the performance of the DTC drive in terms of switching frequency and stator flux estimation, two simple techniques are proposed. The

Nik Rumzi Nik Idris; A. H. M. Yatim; Naziha Ahmad Azli

2001-01-01

116

Reluctant network-based investigation of a claw pole alternator with DC excitation in the stator  

Microsoft Academic Search

Purpose – The purpose of this paper is to propose improvement of the generation capability of a claw pole alternator with DC excitation in the stator (CPAES) using analytical investigation based on a dedicated reluctant model. Design\\/methodology\\/approach – The paper analyzes the effects of geometry and material transformations of the magnetic circuit on the generation capability of the CPAES as

Helmi Aloui; Amina Ibala; Ahmed Masmoudi; Mohamed Gabsi; Michel Lécrivain

2008-01-01

117

Stator short circuits detection in PMSM by means of Hilbert-Huang transform and energy calculation  

Microsoft Academic Search

This paper presents and analyzed short circuit failures for permanent magnet synchronous motor (PMSM). The study includes stated state and dynamic condition for experimental test. The stator current is analyzed by means of Hilbert-Huang transform (HHT) and energy spectrum.

J. Urresty; J. Riba; L. Romeral; J. Rosero; J. Serna

2009-01-01

118

Highly Loaded Multi-Stage Fan Drive Turbine Leaned Stator Configuration Design.  

National Technical Information Service (NTIS)

The results of the high lift blade configuration design study are reported. The three-stage constant-inside-diameter turbine utilizes a ten degree tangentially leaned stator in stage three. All other bladerows use plain blades. Analysis of the leaned stat...

D. C. Evans G. W. Wolfmeyer

1972-01-01

119

Ultra-high speed permanent magnet axial gap alternator with multiple stators  

SciTech Connect

An ultra-high speed, axial gap alternator that can provide an output to a plurality of loads, the alternator providing magnetic isolation such that operating conditions in one load will not affect operating conditions of another load. This improved alternator uses a rotor member disposed between a pair of stator members, with magnets disposed in each of the rotor member surfaces facing the stator members. The magnets in one surface of the rotor member, which alternate in polarity, are isolated from the magnets in the other surface of the rotor member by a disk of magnetic material disposed between the two sets of magnets. In the preferred embodiment, this disk of magnetic material is laminated between two layers of non-magnetic material that support the magnets, and the magnetic material has a peripheral rim that extends to both surfaces of the rotor member to enhance the structural integrity. The stator members are substantially conventional in construction in that equally-spaced and radially-oriented slots are provided, and winding members are laid in these slots. A unit with multiple rotor members and stator members is also described. 6 figs.

Hawsey, R.A.; Bailey, J.M.

1990-03-28

120

Performance and magnetic analysis of the novel stator structure compared with a standard induction machine  

Microsoft Academic Search

In the companion papers, the reduction in the space harmonic effects resulting from constructional changes and new design concepts were explained. In this paper, an induction motor with a novel winding and stator structure and a standard squirrel cage motor are compared, both magnetically and in terms of their operational and constructional data. Calculations for the design of both motors

D. A. Kocabas; A. F. Mergen

2008-01-01

121

Effect of endwall cooling on secondary flows in turbine stator vanes  

NASA Technical Reports Server (NTRS)

An experimental investigation was performed to determine the effect of endwall cooling on the secondary flow behavior and the aerodynamic performance of a coreturbine stator vane. The investigation was conducted in a cold-air, full-annular cascade, where three-dimensional effects could be obtained. Two endwall cooling configurations were tested. In the first configuration, the cooling holes were oriented so that the coolant was injected in line with the inviscid streamline direction. In the second configuration, the coolant was injected at an angle of 15 deg to the inviscid streamline direction and oriented toward the vane pressure surface. In both cases the stator vanes were solid and uncooled so that the effect of endwall cooling could be obtained directly. Total-pressure surveys were taken downstream of the stator vanes over a range of cooling flows at the design, mean-radius, critical velocity ratio of 0.778. Changes in the total-pressure contours downstream of the vanes were used to obtain the effect of endwall cooling on the secondary flows in the stator. Comparisons were made between the two cooled-endwall configurations and with the results obtained previously for solid endwalls.

Goldman, L. J.; Mclallin, K. L.

1977-01-01

122

Equivalent Circuit of the Primitive Rotating Machine With Asymmetrical Stator and Rotor  

Microsoft Academic Search

The equations and equivalent circuits of all standard types of rotating electric machinery operating under arbitrary conditions may be derived as special cases of a single generalized rotating machine, the so-called primitive machine. This paper derives the steady-state equivalent circuit of the primitive machine having unbalanced rotor as well as stator. That is, the load or transmission line connected to

Gabriel Kron

1947-01-01

123

Novel modeling technique for the stator of traveling wave ultrasonic motors.  

PubMed

Traveling wave ultrasonic motors (TWUM) are a promising type of piezoelectric transducers, which are based on the friction transmission of mechanical propagating waves. These waves are excited on the stator by using high Q piezoelectric ceramics. This article presents a modeling strategy, which allows for a quick and precise modal and forced analysis of the stator of TWUM. First-order shear deformation laminated plate theory is applied to annular subdomains (super-elements) of the stator. In addition to shear deformations, the model takes into account the effect of rotary inertia, the stiffness contribution of the teeth, and the linear varying thickness of the stator. Moreover, the formulation considers a more realistic function for the electric field inside the piezoelectric ceramic, i.e., a linear function, instead of the generally assumed constant electric field. The Ritz method is used to find an approximated solution for the dynamic equations. Finally, the modal response is obtained and compared against the results from classical simplified models and the finite element method. Thus, the high accuracy and short computation times of the novel strategy were demonstrated. PMID:14682626

Pons, José L; Rodríguez, Humberto; Ceres, Ramón; Calderón, Leopoldo

2003-11-01

124

A Non-Standard Robust Adaptive Stator Current Control Strategy for Induction Motor Drives  

Microsoft Academic Search

This paper presents a new robust adaptive current control strategy for induction motor drive systems. This control scheme is based on an adaptive pole placement control strategy (APPC) integrated to a sliding mode control scheme (SMC). The proposed APPC employs the internal model principle for achieving a zero steady state tracking error of machine stator currents. Moreover, this current controller

R. L. A. Ribeiro; C. B. Jacobina; A. D. Araiijo; M. B. Santos; A. C. Oliveira

2007-01-01

125

Terminal voltage control of a wind turbine driven isolated induction generator using stator oriented field control  

Microsoft Academic Search

This paper presents the voltage build up process and terminal voltage control in an isolated wind powered induction generator driven by a variable speed wind turbine using stator flux oriented vector control. Here three-phase induction generator is excited using a PWM inverter\\/rectifier connected to a single capacitor on the DC side. Wind powered isolated induction generators have an input, wind,

D. Seyoum; M. F. Rahman; C. Grantham

2003-01-01

126

A Parametric Study of Unsteady Rotor-Stator Interaction in a Simplified Francis Turbine  

NASA Astrophysics Data System (ADS)

CFD analysis is becoming a critical stage in the design of hydroturbines. However, its capability to represent unsteady flow interactions between the rotor and stator (which requires a 360-degree, mesh-refined model of the turbine passage) is hindered. For CFD to become a more effective tool in predicting the performance of a hydroturbine, the key interactions between the rotor and stator need to be understood using current numerical methods. As a first step towards evaluating this unsteady behavior without the burden of a computationally expensive domain, the stator and Francis-type rotor blades are reduced to flat plates. Local and global variables are compared using periodic, semi-periodic, and 360-degree geometric models and various turbulence models (k-omega, k-epsilon, and Spalart-Allmaras). The computations take place within the OpenFOAM^ environment and utilize a general grid interface (GGI) between the rotor and stator computational domains. The rotor computational domain is capable of dynamic rotation. The results demonstrate some of the strengths and limitations of utilizing CFD for hydroturbine analysis. These case studies will also serve as tutorials to help others learn how to use CFD for turbomachinery.

Wouden, Alex; Cimbala, John; Lewis, Bryan

2011-11-01

127

On the use of surface porosity to reduce wake-stator interaction noise  

Microsoft Academic Search

An innovative application of existing technology is proposed for attenuating the effects of transient phenomena, such as rotor-stator and rotor-strut interactions, linked to noise and fatigue failure in turbomachinery environments. A computational study was designed to assess the potential of Passive Porosity Technology as a mechanism for alleviating interaction effects and radiated noise by reducing the fluctuating forces acting on

Ana Fiorella Tinetti

2001-01-01

128

Stator Conductor and Bore Seal Study for the Advanced High-Power Generator Program.  

National Technical Information Service (NTIS)

This report describes the results of a preliminary study to simplify the 36-strand, liquid-cooled stator conductor for the advanced 5-Mw, high-power generator. A specially configured four-strand conductor significantly simplifies the fabrication process w...

A. Druzsba

1986-01-01

129

Development and analysis of a longitudinal and torsional type ultrasonic motor with two stators.  

PubMed

In this paper, a new longitudinal and torsional type ultrasonic motor with two stators is presented and investigated. Normally, such a motor consists of one rotor and one stator, and two types of transducers that are longitudinal PZT and torsional PZT are used to generate the desired elliptical locus on the stator surface. The operating frequency is at the resonance frequency of torsional transducer. In order to enhance the efficiency of the motor, however, the resonance frequencies of both transducers should be closed to each other. For the purpose of matching the resonance frequencies, a symmetrical structure is adopted in design of the motor. Furthermore, two rings are added to the stators in order to adjust the resonance frequencies of these two transducers. A finite element model is developed and ANSYS software is used to analyze the resonance frequencies of longitudinal vibration and torsional vibration as well as optimize the motor geometry. According to the FE results, an experimental prototype is fabricated and the experimental results agree well with the theoretical predictions. PMID:15878188

Yi, Youping; Seemann, Wolfgang; Gausmann, Rainer; Zhong, Jue

2005-08-01

130

Implementation of direct stator flux orientation control on a versatile DSP based system  

Microsoft Academic Search

The implementation of direct stator flux orientation (DSFO) control for induction machines on a versatile Motorola 56000 digital signal processor (DSP) based system is described. Some practical aspects of implementing DSFO control, such as parameter identification, flux estimation, and rotor angular velocity estimation, are discussed. Experimental results are presented to show the performance of a DSFO-controlled induction machine drive. Comparison

Xingyi Xu; Donald W. Novotny

1991-01-01

131

In-service evaluation of motor and generator stator windings using partial discharge tests  

Microsoft Academic Search

Partial discharges (corona) are a symptom of most types of deterioration of motor and generator stator windings rated 4 kV and above. Experience indicates that partial discharges occur years before failure. This leaves sufficient time to plan corrective maintenance to avoid the in-service failure of the motor or generator. This paper describes a new type of partial discharge test which

Greg C. Stone; Howard G. Sedding

1995-01-01

132

Comparison of Computational Aeroacoustics Prediction of Acoustic Transmission Through a 3D Stator With Experiment  

NASA Technical Reports Server (NTRS)

In this paper, numerical predictions of acoustic transmission through a 3D stator obtained using the NASA BASS code are compared with experimentally measured data. The influence of vane count and stagger as well as frequency and mode order on the transmission loss is investigated. The data-theory comparisons indicate that BASS can predict all the important trends observed in the experimental data.

Hixon, Ray; Envia, Edmane; Dahl, Milo; Sutliff, Daniel L.

2014-01-01

133

Voltage grading model for high voltage electric generator stator coil end turn regions  

Microsoft Academic Search

Semiconductive tapes are applied to the end turn region of high voltage stator coils to reduce corona discharge at the slot exit region. The nonlinear, stress grading tapes are used to even out the voltage stress resulting in a more even distribution which also reduces the maximum stress level. To be able to optimize the stress grading capabilities of the

F. T. Emery; D. C. Johnson

1998-01-01

134

Evaluation of epoxy V.P.I. insulation for high voltage stator windings  

Microsoft Academic Search

Epoxy bonded high voltage mica based stator insulation systems have been produced for many years. One such system employing an epoxide\\/anhydride impregnating resin, Neccobond “E” was introduced by National Electric Coil to satisfy customer requests for an epoxy bonded insulation system. The original base materials had been successfully applied in Europe since the 1960's. However before this product was accepted

James E. Timperley; Beant S. Nindra

2000-01-01

135

Traveling-wave piezoelectric linear motor Part I: the stator design.  

PubMed

A new type of piezoelectric linear motor incorporating a traveling wave has been developed. The linear motor is comprised of a stator and a carriage. The stator design, which consists of a meander-line structure and gear teeth mounted on the meander-line structure, is the focus of this article. The meander-line structure is constructed with bimorph actuators arranged in a line. These actuators are driven by two phased sets of alternating current (ac) in order to generate a traveling wave. The traveling wave is transferred to the gear teeth, by which the carriage is driven. Modeling of the stator is derived by use of a strain energy method. The performance of various materials is evaluated by analytical and experimental methods. The analytical and the experimental results are quite approximate. Modal analysis is investigated using ANSYS. Appropriate modes associated with ultrasonic levels of resonant frequency are selected to obtain desired motion and to enhance the output performance. Surface speed for various applied input voltage are studied and indicate a nearly linear relationship. The stator in combination with the carriage makes up the linear motor. PMID:17441594

Ting, Yung; Chen, Liang-Chiang; Li, Chun-Chung; Huang, Jeng-Lin

2007-04-01

136

Deterioration of slot stress control materials on generator stator conductors by non-mechanical mechanisms  

Microsoft Academic Search

Long-term aging experiments conducted to examine mechanisms which could degrade a stator conductor slot stress control system are described. Models consisting of two conductor bars in a short length of core, single conductor bars, and other arrangements were used to investigate the development of slot discharge and compare the performances of various materials. Damage was found to start in the

J. W. Wood; R. T. Hindmarch

1990-01-01

137

Stator Diffusion Enhancement Using a Re-Circulating Co-Flowing Steady Jet (Postprint).  

National Technical Information Service (NTIS)

This paper outlines a steady flow control technique that augments the diffusion process within a stator passage via a continuous co-flowing secondary flow stream along the suction surface. The technique is similar to that used for flow vectoring in nozzle...

D. Carr G. Zha J. Estevadeordal N. J. Kuprowicz W. Copenhaver

2004-01-01

138

Research on location and speed detection for high speed maglev train based on long stator  

Microsoft Academic Search

Location and speed detection (LSD) is one of the key technologies of high speed maglev train. The traction system needs precise location and speed information to carry out the traction task of the train normally and reliably. Firstly, several conventional location and speed detection methods are introduced. And then, the method based on the tooth and slots of long stator

Xue Song; Dai Chunhui; Long Zhiqiang

2010-01-01

139

Novel error sensing microphone arrays for active control of turbofan rotor\\/stator tones  

Microsoft Academic Search

Active control of turbofan rotor\\/stator interaction tones is complicated by the simultaneous presence of multiple duct propagation modes. In-duct error sensing microphone arrays that can adequately resolve these modes typically require duct lengths that are incompatible with modern compact engine design. Two alternative approaches have been investigated. For inlet noise, an external linear array of microphones was positioned in the

Bruce E. Walker; Alan S. Hersh; Edward J. Rice; Daniel L. Sutliff

2003-01-01

140

Improved groundwall insulation for VPI'ed high voltage stator coils  

Microsoft Academic Search

Improved dielectric performance of VPI'ed high voltage stator coils has been developed through a mica paper tape improvement program. The objectives of the program were to develop a glass-backed mica tape with higher dielectric properties than commercially available mica tapes. Tapes with improved dielectric properties allow a reduction in coil groundwall thickness which improves the thermal performance which in turn

F. T. Emery; J. D. B. Smith

1997-01-01

141

Synthesis of cogging-torque waveform from analysis of a single stator slot  

Microsoft Academic Search

A simple analytical technique is proposed to synthesize the cogging-torque waveform of a permanent-magnet brushless machine from the cogging torque, which is associated with a single stator slot. An analytical expression is derived, which reveals the relationship between the two. It is then applied to two motors, which have a fractional number of slots per pole. It is shown that

Z. Q. Zhu; S. Ruangsinchaiwanich; David Howe

2006-01-01

142

Hilbert versus Concordia transform for three-phase machine stator current time-frequency monitoring  

NASA Astrophysics Data System (ADS)

This paper deals with mechanical fault diagnosis in three-phase induction machines from stator current measurements. According to machine models, mechanical faults lead to amplitude and/or phase modulations of the measured stator current with possibly time varying carrier frequency. The modulation diagnosis requires a univocal definition of the instantaneous phase and amplitude. This is performed by associating a complex signal to the real measured one. For a convenient separate modulation diagnosis, the complex signal instantaneous phase and amplitude are expected to carry, respectively, information about the phase and amplitude modulations. The complex signal is classically obtained through the Hilbert transform. Under Bedrosian conditions, the so-called analytic signal allows a separate modulation diagnosis. However, mechanical faults may also produce fast modulations violating the Bedrosian conditions. This study proposes an alternative complex signal representation which takes advantage of the three stator current measurements available in a three-phase machine. From two stator current measurements, the Concordia transform builds a complex vector, the so-called space vector, which unconditionally allows separate modulation diagnosis. This paper applies and compares the Hilbert and Concordia transforms, theoretically and in case of simulated and experimental signals with various modulation frequency ranges.

Trajin, Baptiste; Chabert, Marie; Regnier, Jérémi; Faucher, Jean

2009-11-01

143

Stability Analysis of Speed and Stator Resistance Estimators for Sensorless Induction Motor Drives  

Microsoft Academic Search

This paper presents an analysis by which the stability of a multiple-input-multiple-output system of simultaneous speed and stator resistance estimators for sensorless induction motor drives can be successfully predicted. The instability problem of an adaptive flux observer (AFO) is deeply investigated. In order to achieve stability over a wide range of operation, a design of the observer feedback gain is

Mohamed S. Zaky

2012-01-01

144

Proposal of 3D-stator structure using soft magnetic composite for PM motor  

Microsoft Academic Search

This paper presents 3-dimentional motor core structure using soft magnetic composite. This motor aims to provide high motor efficiency compared with lamination core motor. Soft magnetic composite is applied to the stator to decrease iron loss. Using the magnetic field analysis by 3-dimentional finite element method, we confirmed the usefulness of proposal structure. Furthermore, we studied in the actual motor,

Yoshiki Okada; Hideo Dohmeki; Shinji Konushi

2010-01-01

145

Predictive torque control of interior permanent magnets synchronous motors in stator co-ordinates  

Microsoft Academic Search

This paper proposes a possible approach to control the synchronous machines with interior (buried) permanent magnets (IPM SM). If properly controlled, this construction allows for an increase in torque through a reluctance component that adds to the main torque caused by the permanent magnets. Since the overall torque depends on the load angle and stator current magnitude, the optimal relationship

Vanja Ambrozic; Klemen Drobnic; Mitja Nemec

2011-01-01

146

Performance of a high-work, low-aspect-ratio turbine stator tested with a realistic inlet radial temperature gradient  

NASA Technical Reports Server (NTRS)

A 0.767-scale model of a turbine stator designed for the core of a high-bypass-ratio aircraft engine was tested with uniform inlet conditions and with an inlet radial temperature profile simulating engine conditions. The principal measurements were radial and circumferential surveys of stator-exit total temperature, total pressure, and flow angle. The stator-exit flow field was also computed by using a three-dimensional Navier-Stokes solver. Other than temperature, there were no apparent differences in performance due to the inlet conditions. The computed results compared quite well with the experimental results.

Stabe, Roy G.; Schwab, John R.

1991-01-01

147

Epoxy Adhesives for Stator Magnet Assembly in Stirling Radioisotope Generators (SRG)  

NASA Technical Reports Server (NTRS)

As NASA seeks to fulfill its goals of exploration and understanding through missions planned to visit the moons of Saturn and beyond, a number of challenges arise from the idea of deep space flight. One of the first problems associated with deep space travel is electrical power production for systems on the spacecraft. Conventional methods such as solar power are not practical because efficiency decreases substantially as the craft moves away from the Sun. The criterion for power generation during deep space missions are very specific, the main points requiring high reliability, low mass, minimal vibration and a long lifespan. A Stirling generator, although fairly old in concept, is considered to be a potential solution for electrical power generation for deep space flight. A Stirling generator works on the same electromagnetic principles of a standard generator, using the linear motion of the alternator through the stationary stator which produces electric induction. The motion of the alternator, however, is produced by the heating and cooling dynamics of pressurized gases. Essentially heating one end and cooling another of a contained gas will cause a periodic expansion and compression of the gas from one side to the other, which a displacer translates into linear mechanical motion. NASA needs to confirm that the materials used in the generator will be able to withstand the rigors of space and the life expectancy of the mission. I am working on the verification of the epoxy adhesives used to bond magnets to the steel lamination stack to complete the stator; in terms of in-service performance and durability under various space environments. Understanding the proper curing conditions, high temperature properties, and degassing problems as well as production difficulties are crucial to the long term success of the generator. system and steel substrate used in the stator. To optimize the curing conditions of the epoxies, modulated differential scanning calorimetry analysis was done as a function of cure time and temperatures. Adhesion bond strength was tested at various temperatures with lap shear samples using Hiperco 50 substrate to ensure that the proper adhesive is being used. To try and solve the problem of bondline thickness, micro glass beads of 0.0017" in diameter were investigated to see if any other physical properties of the epoxy were affected. Efforts will be made to develop a standard, optimized, fabrication process/procedure of sub-scale magnet-stator assemblies for various adhesive performance evaluation studies under simulated generator conditions. Also, accelerated aging testing will be done in a pressurized canister with stator assembly samples for three years to verify if any degassing or thermal degradation of the epoxy occurs. The necessity of verifying the correct epoxy adhesive system for the stator magnet in the SRG is crucial because failure of the stator assembly would jeopardize the electrical system, and thereby the entire mission itself. My work involves specimen fabrications, testing, and data analyses of the epoxy adhesive system for the stator magnet in the SRG is crucial because failure of the stator assembly would jeopardize the electrical system, and thereby the entire mission itself.

Cater, George M.

2004-01-01

148

Simulation of unsteady flows through stator and rotor blades of a gas turbine using the Chimera method  

NASA Technical Reports Server (NTRS)

A two-dimensional model to solve compressible Navier-Stokes equations for the flow through stator and rotor blades of a turbine is developed. The flow domains for the stator and rotor blades are coupled by the Chimera method that makes grid generation easy and enhances accuracy because the area of the grid that have high turning of grid lines or high skewness can be eliminated from the computational domain after the grids are generated. The results of flow computations show various important features of unsteady flows including the acoustic waves interacting with boundary layers, Karman vortex shedding from the trailing edge of the stator blades, pulsating incoming flow to a rotor blade from passing stator blades, and flow separation from both suction and pressure sides of the rotor blades.

Nakamura, S.; Scott, J. N.

1993-01-01

149

Study on the Ring Type Stator Design Technique for a Traveling Wave Rotary Type Ultrasonic Motor  

NASA Astrophysics Data System (ADS)

In this paper, the technique of design for the stator of traveling wave rotary type ultrasonic motor was proposed. To establish the design technique, the distribution of internal stresses of the stator was analyzed by applying the cylindrical bodies contact model of Hertz theory and the concept of ``horn effect'' was used to consider the influence of the projection structure. To verify the proposed technique, the prototype motor was fabricated on the authority of the projection shape dimension and the design specification. And its performance was evaluated. According to the estimate production of the experiment results using the extrapolation, we confirmed that the values obtained through the verification experiment were similar to those deduced by the proposed method properly.

Oh, Jin-Heon; Yuk, Hyung-Sang; Lim, Kee-Joe

2012-09-01

150

Ultra-high speed permanent magnet axial gap alternator with multiple stators  

SciTech Connect

This patent describes an ultra-high speed, axial gap alternator that can provide an output to loads, the alternator providing magnetic isolation such that operating conditions in one load will not affect operating conditions of another load. This improved alternator uses a rotor member disposed between a pair of stator members, with magnets disposed in each of the rotor member surfaces facing the stator members. The magnets in one surface of the rotor member, which alternate in polarity, are isolated from the magnets in the other surface of the rotor member by a disk of magnetic material disposed between the two sets of magnets. In the preferred embodiment, this disk of magnetic material is laminated between two layers of non-magnetic material that support the magnets, and the magnetic material has a peripheral rim that extends to both surfaces of the rotor member to enhance the structural integrity.

Hawsey, R.A.; Bailery, J.M.

1991-02-26

151

System and method for determining stator winding resistance in an AC motor  

DOEpatents

A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

Lu, Bin (Kenosha, WI) [Kenosha, WI; Habetler, Thomas G. (Snellville, GA) [Snellville, GA; Zhang, Pinjia (Atlanta, GA) [Atlanta, GA; Theisen, Peter J. (West Bend, WI) [West Bend, WI

2011-05-31

152

Novel error sensing microphone arrays for active control of turbofan rotor/stator tones  

NASA Astrophysics Data System (ADS)

Active control of turbofan rotor/stator interaction tones is complicated by the simultaneous presence of multiple duct propagation modes. In-duct error sensing microphone arrays that can adequately resolve these modes typically require duct lengths that are incompatible with modern compact engine design. Two alternative approaches have been investigated. For inlet noise, an external linear array of microphones was positioned in the near/far radiation field transition region and weighted to provide error signals resolved either by duct mode or by radiation angle. For the exhaust, radially spaced microphones have been placed on duct bifurcation panels to provide supplemental radial-mode resolution. The concepts were tested in combination with an adaptive segmented liner in a static duct and as part of an active stator-vane system in the ANCF research facility at NASA/Glenn Research Center. [Work sponsored by NASA/Langley Research Center.

Walker, Bruce E.; Hersh, Alan S.; Rice, Edward J.; Sutliff, Daniel L.

2003-10-01

153

System and method for determining stator winding resistance in an AC motor using motor drives  

SciTech Connect

A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

Lu, Bin; Habetler, Thomas G; Zhang, Pinjia

2013-02-26

154

A new stator-flux orientation strategy for flux-switching permanent motor drive based on voltage space-vector  

Microsoft Academic Search

In this paper, a new control strategy of stator-flux orientation for flux-switching permanent magnet (FSPM) motor based on voltage space-vector is proposed. The fundamental relationship and equalization between the two magnetic fields where the magnets are in the stator and rotor, respectively, are analyzed. The space-vector pulse-width modulation technique is applied to the FSPM motor drive in which the fixed

Hongyun Jia; Ming Cheng; Wei Hua; Wenxiang Zhao; Wei Lu

2008-01-01

155

Stator and Rotor Pole Combinations for Multi-Tooth Flux-Switching Permanent-Magnet Brushless AC Machines  

Microsoft Academic Search

A simple analytical method is developed for determining the optimal combination of stator pole and rotor pole numbers for a multi-tooth flux-switching permanent magnet (FSPM) machine, and the optimal design of the stator teeth for maximum torque. In addition, the rotor pole width and the split ratio are optimized by finite element analysis. The optimized multi-tooth FSPM machine exhibits a

J. T. Chen; Z. Q. Zhu; D. Howe

2008-01-01

156

Comparison of all and alternate poles wound flux-switching PM machines having different stator and rotor pole numbers  

Microsoft Academic Search

The influence of stator and rotor pole numbers, viz. 6\\/5, 6\\/7, 12\\/10, 12\\/11, 12\\/13, and 12\\/14 stator\\/rotor poles, etc., on the electromagnetic performance of 3-phase flux-switching PM (FSPM) machines with all and alternate poles wound is investigated in this paper. It shows that the back-emf waveform, winding inductance, unbalanced magnetic force (UMF) and torque density in a FSPM machine are

J. T. Chen; Z. Q. Zhu

2009-01-01

157

Comparison of All and Alternate-Poles-Wound Flux-Switching PM Machines Having Different Stator and Rotor Pole Numbers  

Microsoft Academic Search

The influence of stator and rotor pole numbers, viz. 6\\/5, 6\\/7, 12\\/10, 12\\/11, 12\\/13, and 12\\/14 stator\\/rotor poles, etc., on the electromagnetic performance of three-phase flux-switching permanent-magnet (FSPM) machines with all and alternate poles wound is investigated in this paper. It shows that the back-EMF waveform, winding inductance, unbalanced magnetic force, and torque density in an FSPM machine are all

J. T. Chen; Z. Q. Zhu

2010-01-01

158

Analytical derivation of a coupled-circuit model of a claw-pole alternator with concentrated stator windings  

Microsoft Academic Search

A lumped-parameter coupled-circuit model of a claw-pole alternator is derived. To derive the model, analytical techniques are used to define a three-dimensional (3-D) Fourier-series representation of the airgap flux density. Included in the series expansion are the harmonics introduced by rotor saliency, concentrated stator windings, and stator slots. From the airgap flux density waveform, relatively simple closed-form expressions for the

Hua Bai; Steven D. Pekarek; Jerry Tichenor; Walter Eversman; Duane J. Buening; Gregory R. Holbrook; Michael L. Hull; Ronald J. Krefta; Steven J. Shields

2002-01-01

159

Analytical derivation of a coupled-circuit model of a claw-pole alternator with concentrated stator winding  

Microsoft Academic Search

Summary form only given as follows. A lumped-parameter coupled-circuit model of a clawpole alternator is derived. To derive the model, analytical techniques are used to define a three-dimensional Fourier-series representation of the airgap flux density. Included in the series expansion are the harmonics introduced by rotor saliency, concentrated stator windings, and stator slots. From the airgap flux density waveform, relatively

H. Bai; S. Pekarek; J. Tichenor; W. Eversman; D. Buening; G. Holbrook; M. Hull; R. Krefta; S. Shields

2002-01-01

160

The effects of turbulence and stator\\/rotor interactions on turbine heat transfer. I - Design operating conditions  

Microsoft Academic Search

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence, stator-rotor axial spacing, and relative circumferential spacing of first and second stators on turbine airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approximately 5X engine), ambient temperature, stage-and-a-half rotating turbine model. The data indicate that while turbine inlet turbulence

M. F. Blair; R. P. Dring; H. D. Joslyn

1988-01-01

161

Analysis of high-voltage generator stator windings sudden three-phase short-circuit and loss of excitation fault  

Microsoft Academic Search

Base on a prototype of the 130 kw\\/5 kv high voltage generator, the system simulation model is set up for the generator stator windings suddenly three-phase short-circuit failure and loss of excitation failures. The dynamic simulation compared with experiment on DJ18-1 synchronous generator, it reaches conclusion that the system simulation model is correct. The current of the high-voltage generator stator

Lv Yan-ling; Ge Bao-jun; Li Cui-cui; Tao Da-jun; Zhang Zhi-qiang

2009-01-01

162

An online identification method for both stator resistance and back-EMF coefficient of PMSMs without rotational transducers  

Microsoft Academic Search

This letter describes an effective online method for identifying both the stator resistance and the back-electromotive-force (EMF) coefficient of a permanent-magnet synchronous motor (PMSM) without rotational transducers. Using only the information of stator currents and voltages, it can provide fairly good identification accuracy under various load conditions and can be easily incorporated into most sensorless speed control schemes proposed in

Kyu-Wang Lee; Doo-Hee Jung; In-Joong Ha

2004-01-01

163

Optimal combination of stator and rotor pole numbers in flux-switching PM brushless AC machines  

Microsoft Academic Search

A simple analytical method is developed to compare the combinations of stator and rotor pole numbers in flux-switching PM machines in terms of back-EMF and electromagnetic torque. The winding connections for machines having all poles and alternate poles wound are determined, based on the coil-EMF vectors. The conditions are established for balanced symmetrical back-EMF waveform. It shows that the optimized

J. T. Chen; Z. Q. Zhu; A. S. Thomas; D. Howe

2008-01-01

164

Stator-flux-based vector control of induction machines in magnetic saturation  

Microsoft Academic Search

In many variable-torque applications of induction machines, it is desirable to operate the machine at high flux levels, thus allowing the machine to produce higher torques. This can lead to saturation of the main flux path, introducing cross-coupling effects which can severely disrupt the performance of controllers dependent on knowledge of the machine's magnetic parameters. Stator flux-oriented torque-control schemes need

Heath Hofmann; Seth R. Sanders; Charles R. Sullivan

1997-01-01

165

A nickel base alloy, NASA WAZ-16, with potential for gas turbine stator vane application  

NASA Technical Reports Server (NTRS)

A nickel-base superalloy based on the nickel-aluminum-tungsten system designated WAZ-16 was developed for high strength in the 1095 C (2000 F) to 1205 C (2200 F) range. Its tensile strength at the latter temperature is approximately 186 MN/m2 (27,000 psi). The combination of properties of the alloy suggest that it has potential as a stator vane material in advanced gas turbine engines.

Waters, W. J.; Freche, J. C.

1974-01-01

166

Unsteady flow investigation in rotor-stator interface of a radial diffuser pump  

Microsoft Academic Search

The flow in a vaned diffuser radial pump is fully turbulent and strongly unsteady, caused by the rotor-stator interaction.\\u000a In this paper, two-dimensional laser Doppler velocimetry (LDV) measurement results have been utilized to investigate the unsteady\\u000a flow in a low specific speed radial diffuser pump with leaning impeller trailing edges. CFD simulations have been also conducted\\u000a to provide more extensive

Jianjun Feng; F. K. Benra; H. J. Dohmen

2010-01-01

167

Diagnostics of an induction-motor rotor by the spectral analysis of stator currents  

NASA Astrophysics Data System (ADS)

A method for achieving more efficient revealing and more unambiguous evaluation of various kinds of defects in the induction-motor (IM) rotor, which is based on changes occurring in the characteristic signs of the spectrum of the stator current, is presented. The results and analysis of measurements performed for artificially specified cases of faults in the rotor of a small-capacity IM are presented.

Weinreb, K.

2013-12-01

168

Laser Doppler, velocimeter system for turbine stator cascade studies and analysis of statistical biasing errors  

NASA Technical Reports Server (NTRS)

A laser Doppler velocimeter (LDV) built for use in the Lewis Research Center's turbine stator cascade facilities is described. The signal processing and self contained data processing are based on a computing counter. A procedure is given for mode matching the laser to the probe volume. An analysis is presented of biasing errors that were observed in turbulent flow when the mean flow was not normal to the fringes.

Seasholtz, R. G.

1977-01-01

169

What stator current processing-based technique to use for induction motor rotor faults diagnosis?  

Microsoft Academic Search

In recent years, marked improvement has been achieved in the design and manufacture of stator winding. However, motors driven by solid-state inverters undergo severe voltage stresses due to rapid switch-on and switch-off of semiconductor switches. Also, induction motors are required to operate in highly corrosive and dusty environments. Requirements such as these have spurred the development of vastly improved insulation

Mohamed El Hachemi Benbouzid; Gerald B. Kliman

2003-01-01

170

Locating of leaks in water-cooled generator stator bars using perfluorocarbon tracers  

SciTech Connect

Water cooled stator bars in power plant generators often fail during the maintenance cycle due to water leakage. After the hydrogen pressure in the generator shell has been released water can leak through cracks in the copper and through the insulation. Leaking bars, but not the leaks themselves, are detected with so-called ``hi-pot`` (high potential) tests where direct electrical current is applied to the stator bar windings. A study initiated by ConEd and Brookhaven`s Tracer Technology Center to explore the cause of these leakage problems to determine if the failures originate in the manufacturing process or are created in service by phase related torque stresses. To this purpose bars that had failed the hi-pot test were investigated first with the insulation in place and then stripped to the bare copper. The bars were pressurized with gases containing perfluorocarbon tracers and the magnitude and location of the leaks was detected by using tracers technology principles and instruments such as the ``double source`` method and the Dual Trap Analyzer. In the second part of the project the windings within a generator were tested in-situ for leaks during an outage using tracer principles. Recommendations are given suggesting the shut down of stator bar cooling water before hydrogen bleeding during outages and a revision of the current vent flow rate. The new standard should establish a reasonable leak rate for the stator bar windings proper and exclude leakage of pump seals and connections. Testing during the maintenance cycle in generators should include routine tracer leak detection following the hi-pot test.

Loss, W.M.; Dietz, R.N.

1991-09-01

171

Locating of leaks in water-cooled generator stator bars using perfluorocarbon tracers  

SciTech Connect

Water cooled stator bars in power plant generators often fail during the maintenance cycle due to water leakage. After the hydrogen pressure in the generator shell has been released water can leak through cracks in the copper and through the insulation. Leaking bars, but not the leaks themselves, are detected with so-called hi-pot'' (high potential) tests where direct electrical current is applied to the stator bar windings. A study initiated by ConEd and Brookhaven's Tracer Technology Center to explore the cause of these leakage problems to determine if the failures originate in the manufacturing process or are created in service by phase related torque stresses. To this purpose bars that had failed the hi-pot test were investigated first with the insulation in place and then stripped to the bare copper. The bars were pressurized with gases containing perfluorocarbon tracers and the magnitude and location of the leaks was detected by using tracers technology principles and instruments such as the double source'' method and the Dual Trap Analyzer. In the second part of the project the windings within a generator were tested in-situ for leaks during an outage using tracer principles. Recommendations are given suggesting the shut down of stator bar cooling water before hydrogen bleeding during outages and a revision of the current vent flow rate. The new standard should establish a reasonable leak rate for the stator bar windings proper and exclude leakage of pump seals and connections. Testing during the maintenance cycle in generators should include routine tracer leak detection following the hi-pot test.

Loss, W.M.; Dietz, R.N.

1991-09-01

172

A novel 20Hz power injection protection scheme for stator ground fault of pumped storage generator  

Microsoft Academic Search

Based on the analysis of the start-up of pumped storage generator under motor circumstance, it is found out that the conventional 20 Hz injection component is influenced by the low frequency component when ground faults take place in the stator windings for static frequency converter (SFC) start-up generator. The conventional relay is just simply blocked in case mal-operation during 20

Zheng Zhu; Yuping Lu

2008-01-01

173

Online capacitance and dissipation factor monitoring of AC motor stator insulation  

Microsoft Academic Search

A new on-line technique for monitoring the insulation condition of AC motor stator winding is proposed. The approach uses a newly developed, High-Sensitivity Current Transformer (HSCT) to precisely and non-invasively measure the differential current (e.g., the insulation leakage current) of each phase winding from the motor junction box. Conventional differential current transformers (CT) used for fault protection can be replaced

Karim Younsi; Prabhakar Neti; Manoj Shah; Joe Yingneng Zhou; John Krahn; Konrad Weeber; David Whitefield

2010-01-01

174

ANFIS-based diagnosis and location of stator interturn faults in PM brushless DC motors  

Microsoft Academic Search

An automatic scheme for fault diagnosis and location of stator-winding interturns in permanent-magnet brushless dc motors is presented. System performances under healthy and faulty operation are obtained via a discrete-time model. Waveform of the electromagnetic torque is monitored and processed using discrete Fourier transform and short-time Fourier transform to derive proper diagnostic indices. Two adaptive neuro-fuzzy inference systems (ANFIS) are

M. A. Awadallah; M. M. Morcos

2004-01-01

175

Evaluation of eddy current losses in axial flux permanent magnet (AFPM) machine with an ironless stator  

Microsoft Academic Search

This paper presents a hybrid method for the calculation of eddy current losses in axial flux permanent magnet (AFPM) machines with an ironless stator. The method combines two-dimensional (2-D) finite element (FE) field solutions with the closed-form formula for eddy current loss calculation. The computational limitations of using 2-D FE modeling are discussed and a multi-slice and multi-layer FE model

R. Wang; A. J. Kamper

2002-01-01

176

Numerical analysis of acoustic effect of rotor wakes in rotor-stator interaction  

Microsoft Academic Search

A critical noise source in turbomachinery due to rotor-stator interaction is studied by the numerical solutions of Navier-Stokes equations. The two-dimensional unsteady flow equations are solved using an implicit upwind finite difference algorithm. A patched grid technique is applied in the multi-grid system. Non-reflecting boundary conditions are applied at inflow and outflow boundaries. It is found that the wake generated

Wei Tang

1992-01-01

177

Acoustic Scattering by Three-Dimensional Stators and Rotors Using the SOURCE3D Code. Volume 1; Analysis and Results  

NASA Technical Reports Server (NTRS)

This report provides a study of rotor and stator scattering using the SOURCE3D Rotor Wake/Stator Interaction Code. SOURCE3D is a quasi-three-dimensional computer program that uses three-dimensional acoustics and two-dimensional cascade load response theory to calculate rotor and stator modal reflection and transmission (scattering) coefficients. SOURCE3D is at the core of the TFaNS (Theoretical Fan Noise Design/Prediction System), developed for NASA, which provides complete fully coupled (inlet, rotor, stator, exit) noise solutions for turbofan engines. The reason for studying scattering is that we must first understand the behavior of the individual scattering coefficients provided by SOURCE3D, before eventually understanding the more complicated predictions from TFaNS. To study scattering, we have derived a large number of scattering curves for vane and blade rows. The curves are plots of output wave power divided by input wave power (in dB units) versus vane/blade ratio. Some of these plots are shown in this report. All of the plots are provided in a separate volume. To assist in understanding the plots, formulas have been derived for special vane/blade ratios for which wavefronts are either parallel or normal to rotor or stator chords. From the plots, we have found that, for the most part, there was strong transmission and weak reflection over most of the vane/blade ratio range for the stator. For the rotor, there was little transmission loss.

Meyer, Harold D.

1999-01-01

178

Acoustic Reflection and Transmission of 2-Dimensional Rotors and Stators, Including Mode and Frequency Scattering Effects  

NASA Technical Reports Server (NTRS)

A reduced order modeling scheme has been developed for the unsteady acoustic and vortical coupling between blade rows of a turbomachine. The essential behavior of the system is governed by modal scattering coefficients (i.e., reflection and transmission coefficients) of the rotor, stator, inlet and nozzle, which are calculated as if they were connected to non-reflecting ducts. The objective of this report is to identify fundamental behavior of these scattering coefficients for a better understanding of the role of blade row reflection and transmission in noise generation. A 2D flat plate unsteady cascade model is used for the analysis with the expectation that the general behavior presented herein will carry over to models that include more realistic flow and geometry. It is shown that stators scatter input waves into many modes at the same frequency whereas rotors scatter on frequency, or harmonic order. Important cases are shown here the rotor reflection coefficient is greater than unity; a mode at blade passing frequency (BPF) traveling from the stator with unit sound power is reflected by the rotor with more than unit power at 2xBPF and 3xBPE Analysis is presented to explain this unexpected phenomenon. Scattering curves are presented in a format chosen for design use and for physical interpretation. To aid in interpretation of the curves, formulas are derived for special condition where waveforms are parallel to perpendicular to the rotor.

Hanson, Donald B.

1999-01-01

179

Periodic transition on an axial compressor stator: Incidence and clocking effects. Part 1: Experimental data  

SciTech Connect

Periodic wake-induced transition on the outlet stator of a 1.5-stage axial compressor is examined using hot-film arrays on both the suction and pressure surfaces. The time-mean surface pressure distribution is varied by changing the blade incidence, while the free-stream disturbance field is altered by clocking of the stator relative to an inlet guide vane row. Ensemble-averaged plots of turbulent intermittency and relaxation factor (extent of calmed flow following the passage of a turbulent spot) are presented. These show the strength of periodic wake-induced transition phenomena to be significantly influenced by both incidence and clocking effects. The nature and extent of transition by other modes (natural, bypass, and separated flow transition) are altered accordingly. Leading edge and midchord separation bubbles are affected in a characteristically different manner by changing free-stream periodicity. There are noticeable differences between suction and pressure surface transition behavior, particularly as regards the strength and extent of calming. In Part 2 of this paper, the transition onset observations from the compressor stator are used to evaluate the quasi-steady application of conventional transition correlations to predict unsteady transition onset on the blading of an embedded axial compressor stage.

Walker, G.J.; Hughes, J.D. [Univ. of Tasmania, Hobart (Australia). School of Engineering; Solomon, W.J. [Ohio Aerospace Institute/General Electric Aircraft Engines, Cincinnati, OH (United States)

1999-07-01

180

Aerodynamic performances of three fan stator designs operating with rotor having tip speed of 337 meters per second and pressure ratio of 1.54. 1: Experimental performance  

NASA Technical Reports Server (NTRS)

The aerodynamic performances of four stator-blade rows are presented and evaluated. The aerodynamic designs of two of these stators were compromised to reduce noise, a third design was not. On a calculated operating line passing through the design point pressure ratio, the best stator had overall pressure-ratio and efficiency decrements of 0.031 and 0.044, respectively, providing a stage pressure ratio of 1.483 and efficiency of 0.865. The other stators showed some correctable deficiencies due partly to the design compromises for noise. In the end-wall regions blade-element losses were significantly less for the shortest chord studied.

Gelder, T. F.

1980-01-01

181

Effects of blade-vane ratio and rotor-stator spacing on fan noise with forward velocity  

NASA Technical Reports Server (NTRS)

A research fan stage is acoustically tested in an anechoic wind tunnel with a 41 m/sec tunnel flow. Two stator vane numbers giving cut-on and cut-off conditions are tested at three rotor stator spacings ranging from 0.5 to 2.0 rotor chords. Hot-film anemometer turbulence measurements are made at the leading edge of the stator for each spacing, and a crossed film anemometer is radially transversed to define streamwise and upwash characteristics of the rotor blade wakes. Trends in the acoustic results are observed in the front and aft quadrants at 80% design fan speed. Aft quadrant results demonstrate a fundamental tone 9 dB lower for the 25 vane stator than for the 11 vane stator, while overtone levels are 3 dB higher. The cut-off criterion strongly controls fundamental tone level at all spacings, and spacing trends of the wake-defect upwash component show good agreement with corresponding cut-on acoustic tone levels.

Woodward, R. P.; Glaser, F. W.

1981-01-01

182

Low-temperature optical studies of C60-cubane rotor-stator compound  

NASA Astrophysics Data System (ADS)

We present here low-temperature Raman and photoluminescence spectra of the C60-cubane rotor-stator compound. We show the continuous evolution of Raman spectra between 77 K and room temperature, with no sharp transition visible at 140 K, the orientational ordering temperature. Low-temperature luminescence spectra of C60 in C60-cubane compound are found to be shifted and better resolved then spectra for pristine C60 at the corresponding temperatures, showing relatively weaker intermolecular interactions. In fact, the solid-state luminescence of C60-cubane is similar to free-molecule C60 luminescence spectra.

Iwasiewicz-Wabnig, A.; Kováts, É.; Pekker, S.; Sundqvist, B.

2008-03-01

183

Detection of stator winding faults in induction machines using flux and vibration analysis  

NASA Astrophysics Data System (ADS)

This work aims at presenting the detection and diagnosis of electrical faults in the stator winding of three-phase induction motors using magnetic flux and vibration analysis techniques. A relationship was established between the main electrical faults (inter-turn short circuits and unbalanced voltage supplies) and the signals of magnetic flux and vibration, in order to identify the characteristic frequencies of those faults. The experimental results showed the efficiency of the conjugation of these techniques for detection, diagnosis and monitoring tasks. The results were undoubtedly impressive and can be adapted and used in real predictive maintenance programs in industries.

Lamim Filho, P. C. M.; Pederiva, R.; Brito, J. N.

2014-01-01

184

Rim seal experiments and analysis of a rotor-stator system with nonaxisymmetric main flow  

NASA Astrophysics Data System (ADS)

To examine the simplified model to predict the ingress flow rate which was formerly proposed by the authors, the sealing characteristics of a shrouded rotor-stator system with a nonaxisymmetric main flow is studied using gas concentration measurements in the wheel-space. The predicted value for the sealing effectiveness as well as the minimum cooling air flow ratio necessary to prevent ingress is shown to be relatively in good agreement with the test results. It is also found that for the precise prediction of the sealing effectiveness, the circumferential static pressure distribution in the annulus is needed.

Hamabe, K.; Ishida, K.

1992-06-01

185

Predicting the Rotor-Stator Interaction Acoustics of a Ducted Fan Engine  

NASA Technical Reports Server (NTRS)

A Navier-Stokes computation is performed for a ducted-fan configuration with the goal of predicting rotor-stator noise generation without having to re- to heuristic modeling. The calculated pressure field in the inlet region is decomposed into classical infinite-duct, modes, which are then used in either a hybrid finite-element /Kirchhoff surface method or boundary integral equation method to calculate the far field noise. Comparisons with experimental data are presented, including rotor wake surveys and far field sound pressure levels for 2 blade passage frequency (BPF) tones.

Biedron, Robert T.; Rumsey, Christopher L.; Podboy, Gary G.; Dunn, M. H.

2001-01-01

186

Experimental investigation of rotor-stator interaction in a centrifugal pump with several vaned diffusers  

NASA Technical Reports Server (NTRS)

Steady and unsteady diffuser vane pressure measurements have been conducted with a two-dimensional test impeller, in an experimental investigation of rotor-stator interaction within a centrifugal pump having several vaned diffusers, under conditions of different flow coefficients and different radial gaps between the impeller blade trailing edge and the diffuser vane leading edge. The largest pressure fluctuations on the diffuser vanes and the impeller blades were found to be of the same order of magnitude as the total pressure rise across the pump. Increasing the number of diffuser vanes was found to result in a significant decrease of impeller blade pressure fluctuations.

Arndt, N.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

1990-01-01

187

Low Speed, 2-D Rotor/Stator Active Noise Control at the Source Demonstration  

NASA Technical Reports Server (NTRS)

Wake/blade-row interaction noise produced by the Annular Cascade Facility at Purdue University has been modeled using the LINFLO analysis. Actuator displacements needed for complete cancellation of the propagating acoustic response modes have been determined, along with the associated actuator power requirements. As an alternative, weighted least squares minimization of the total far-field sound power using individual actuators has also been examined. Attempts were made to translate the two-dimensional aerodynamic results into three-dimensional actuator requirements. The results lie near the limit of present actuator technology. In order to investigate the concept of noise control at the source for active rotor/stator noise control at the source, various techniques for embedding miniature actuators into vanes were examined. Numerous miniature speaker arrangements were tested and analyzed to determine their suitability as actuators for a demonstration test in the Annular Cascade Facility at Purdue. The best candidates demonstrated marginal performance. An alternative concept to using vane mounted speakers as control actuators was developed and tested. The concept uses compression drivers which are mounted externally to the stator vanes. Each compression driver is connected via a tube to an air cavity in the stator vane, from which the driver signal radiates into the working section of the experimental rig. The actual locations and dimensions of the actuators were used as input parameters for a LINFLO computational analysis of the actuator displacements required for complete cancellation of tones in the Purdue experimental rig. The actuators were designed and an arrangement determined which is compatible with the Purdue experimental rig and instrumentation. Experimental tests indicate that the actuators are capable of producing equivalent displacements greater than the requirements predicted by the LINFLO analysis. The acoustic output of the actuators was also found to be unaffected by the presence of air flow representative of the Purdue experimental rig. A test of the active noise control at the source concept for rotor/stator active noise control was demonstrated. This 2-D test demonstrated conclusively the simultaneous reduction of two acoustic modes. Reductions of over 10 dB were obtained over a wide operating range.

Simonich, John C.; Kousen, Ken A.; Zander, Anthony C.; Bak, Michael; Topol, David A.

1997-01-01

188

Compact piezoelectric micromotor with a single bulk lead zirconate titanate stator  

NASA Astrophysics Data System (ADS)

The advance of micro/nanotechnology promotes the development of micromotors in recent years. In this article, a compact piezoelectric ultrasonic micromotor with a single bulk lead zirconate titanate stator is proposed. A traveling wave is generated by superposition of bending modes with 90° phase difference excited by d15 inverse piezoelectric effects. The operating principle simplifies the system structure significantly, and provides a miniaturization solution. A research prototype with the size of 0.75× 0.75×1.55 mm is developed. It can produce start-up torque of 0.27?Nmand maximum speed of 2760 r/min at 14RMS.

Yan, Liang; Lan, Hua; Jiao, Zongxia; Chen, Chin-Yin; Chen, I.-Ming

2013-04-01

189

Predicting the Rotor-Stator Interaction Acoustics of a Ducted Fan Engine  

NASA Technical Reports Server (NTRS)

A Navier-Stokes computation is performed for a ducted-fan configuration with the goal of predicting rotor-stator noise generation without having to resort to heuristic modeling. The calculated pressure field in the inlet region is decomposed into classical infinite-duct modes, which are then used in either a hybrid finite-element/Kirchhoff surface method or boundary integral equation method to calculate the far field noise. Comparisons with experimental data are presented, including rotor wake surveys and far field sound pressure levels for two blade passage frequency (BPF) tones.

Biedron, Robert T.; Rumsey, Christopher L.; Podboy, Gary G.; Dunn, M. H.

2001-01-01

190

Comparison of calculated and experimental cascade performance for controlled-diffusion compressor stator blading  

NASA Technical Reports Server (NTRS)

The mid-span section of a previously reported controlled-diffusion compressor stator has been experimentally evaluated in cascade. Measurements are taken over a range of incidence angles for blade chord Reynolds numbers from 470,000 to 690,000. Blade chord length is 12.7 cm, aspect ratio is 2.0, and solidity is 1.67. Measurements include conventional cascade performance parameters as well as blade surface pressures. Computations are made for the inviscid flow field, surface boundary layers, and loss for several of the blade inlet angle conditions, are compared against corresponding data.

Sanger, N. L.; Shreeve, R. P.

1986-01-01

191

Comparison of steady and unsteady secondary flows in a turbine stator cascade  

NASA Technical Reports Server (NTRS)

The effect of periodic rotor wakes on the secondary flow structure in a turbine stator cascade was investigated. A mechanism simulated the wakes shed from rotor blades by passing cylindrical rods across the inlet to a linear cascade installed in a recirculating water flow loop. Velocity measurements showed a passage vortex, similar to that seen in steady flow, during the time associated with undisturbed fluid. However, as the rotor wake passed through the blade row, a large crossflow toward the suction surface was observed in the midspan region. This caused the development of two large areas of circulation between the midspan and endwall regions, significantly distorting and weakening the passage vortices.

Hebert, Gregory J.; Tiederman, William G.

1989-01-01

192

Method for the determination of the three-dimensional aerodynamic field of a rotor-stator combination to compressible flow  

NASA Technical Reports Server (NTRS)

Using the lifting surface theory and the acceleration potential method for the flow field of an axial turbocompressor stage, a recursive and a direct method are presented that make use of the eigenfunction solutions of the isolated rotor and stator to solve for the rotor-stator interaction problem. The net pressure distribution on the rotor and stator blades is represented by modified Birnbaum series, whose coefficients are determined using a matrix procedure and satisfying the boundary conditions on the surface of the blades. The relation between the matrix operators of the recursive and the direct methods is also shown. Expressions have been given for the blade circulation, the axial and tangential forces on the blade, the rotor power required, and the induced upwash velocity of the stage.

Ramachandra, Sridhar M.; Bober, Lawrence J.; Khandelwal, Suresh

1987-01-01

193

Numerical investigation of base-setting of stator's stagger angles for a 15-stage axial-flow compressor  

NASA Astrophysics Data System (ADS)

A 15-stage axial-flow compressor utilized in steel industry was studied in this paper. All the stator's stagger angles of the compressor are variable to ensure the multistage compressor operate effectively within a wide range of flow rate and meanwhile satisfy the demand for sufficient pressure ratio, adiabatic efficiency and stall margin. Three in all different base-settings of stator's stagger angles were presented and commercial CFD software was applied to obtain the overall performance characteristics. The results showed that both of the optimized base-settings improved the performances both in summer and winter conditions, although the adiabatic efficiency was somewhat decreased. Taking incidence angle and stage loading into consideration, differences among the three cases were analyzed in detail. On the basis of numerical computations, the performance could be effectively improved through adjusting the base-setting of stator's stagger angles.

Chang, Hao; Zhao, Weiguang; Jin, Donghai; Peng, Zeyan; Gui, Xingmin

2014-02-01

194

Flexibility within the rotor and stators of the vacuolar H+-ATPase.  

PubMed

The V-ATPase is a membrane-bound protein complex which pumps protons across the membrane to generate a large proton motive force through the coupling of an ATP-driven 3-stroke rotary motor (V1) to a multistroke proton pump (Vo). This is done with near 100% efficiency, which is achieved in part by flexibility within the central rotor axle and stator connections, allowing the system to flex to minimise the free energy loss of conformational changes during catalysis. We have used electron microscopy to reveal distinctive bending along the V-ATPase complex, leading to angular displacement of the V1 domain relative to the Vo domain to a maximum of ~30°. This has been complemented by elastic network normal mode analysis that shows both flexing and twisting with the compliance being located in the rotor axle, stator filaments, or both. This study provides direct evidence of flexibility within the V-ATPase and by implication in related rotary ATPases, a feature predicted to be important for regulation and their high energetic efficiencies. PMID:24312643

Song, Chun Feng; Papachristos, Kostas; Rawson, Shaun; Huss, Markus; Wieczorek, Helmut; Paci, Emanuele; Trinick, John; Harrison, Michael A; Muench, Stephen P

2013-01-01

195

Heat production in the windings of the stators of electric machines under stationary condition  

NASA Astrophysics Data System (ADS)

In electric machines due to high currents and resistive losses (joule heating) heat is produced. To avoid damages by overheating the design of effective cooling systems is required. Therefore the knowledge of heat sources and heat transfer processes is necessary. The purpose of this paper is to illustrate a good and effective calculation method for the temperature analysis based on homogenization techniques. These methods have been applied for the stator windings in a slot of an electric machine consisting of copper wires and resin. The key quantity here is an effective thermal conductivity, which characterizes the heterogeneous wire resin-arrangement inside the stator slot. To illustrate the applicability of the method, the analysis of a simplified, homogenized model is compared with the detailed analysis of temperature behavior inside a slot of an electric machine according to the heat generation. We considered here only the stationary situation. The achieved numerical results are accurate and show that the applied homogenization technique works in practice. Finally the results of simulations for the two cases, the original model of the slot and the homogenized model chosen for the slot (unit cell), are compared to experimental results.

Alebouyeh Samami, Behzad; Pieper, Martin; Breitbach, Gerd; Hodapp, Josef

2014-05-01

196

The use of cowl camber and taper to reduce rotor/stator interaction noise  

NASA Technical Reports Server (NTRS)

The project had two specific technical objectives: (1) to develop a realistic three-dimensional model of tonal noise due to rotor/stator interaction, as the input field for predictions of diffraction and dissipation by a lined cowl; and (2) to determine whether the generator curve of that cowl, or duct, could be 'steered' to yield substantially lower values of propulsor noise along the engine's fore and aft open sectors. The more general and important aim of their research is to provide the commercial aircraft industry with a useful predictive tool to help it meet its noise-reduction goals. The work has produced a tractable and yet realistic model of rotor/stator interaction noise. The blades in the fan stage are radially divergent, twisted, and of realistically wide chords to match the high frequencies and speeds of the sound-production process. The resulting three-dimensional acoustic nearfield insonifies the interior wall of the diffracting cowl, whose shape, incidentally, does not affect fore or aft noise significantly (but other factors do).

Martinez, R.

1995-01-01

197

Advanced single permanent magnet axipolar ironless stator ac motor for electric passenger vehicles  

NASA Technical Reports Server (NTRS)

A program was conducted to design and develop an advanced-concept motor specifically created for propulsion of electric vehicles with increased range, reduced energy consumption, and reduced life-cycle costs in comparison with conventional systems. The motor developed is a brushless, dc, rare-earth cobalt, permanent magnet, axial air gap inductor machine that uses an ironless stator. Air cooling is inherent provided by the centrifugal-fan action of the rotor poles. An extensive design phase was conducted, which included analysis of the system performance versus the SAE J227a(D) driving cycle. A proof-of-principle model was developed and tested, and a functional model was developed and tested. Full generator-level testing was conducted on the functional model, recording electromagnetic, thermal, aerodynamic, and acoustic noise data. The machine demonstrated 20.3 kW output at 1466 rad/s and 160 dc. The novel ironless stator demonstated the capability to continuously operate at peak current. The projected system performance based on the use of a transistor inverter is 23.6 kW output power at 1466 rad/s and 83.3 percent efficiency. Design areas of concern regarding electric vehicle applications include the inherently high windage loss and rotor inertia.

Beauchamp, E. D.; Hadfield, J. R.; Wuertz, K. L.

1983-01-01

198

Hydroacoustic simulation of rotor-stator interaction in resonance conditions in Francis pump-turbine  

NASA Astrophysics Data System (ADS)

Combined effect of rotating pressure field related to runner blade and wakes of wicket gates leads to rotor stator interactions, RSI, in Francis pump-turbines. These interactions induce pressures waves propagating in the entire hydraulic machine. Superposition of those pressure waves may result in standing wave in the spiral casing and rotating diametrical mode in the guide vanes and can cause strong pressure fluctuations and vibrations. This paper presents the modeling, simulation and analysis of Rotor-Stator Interaction of a scale model of a Francis pump-turbine and related test rig using a one-dimensional approach. The hydroacoustic modeling of the Francis pump-turbine takes into account the spiral casing, the 20 guide vanes, the 9 rotating runner vanes. The connection between stationary and rotating parts is ensured by a valve network driven according to the unsteady flow distribution between guide vanes and runner vanes. Time domain simulations are performed for 2 different runner rotational speeds in turbine mode. The simulation results are analyzed in frequency domain and highlights hydroacoustic resonance between RSI excitations and the spiral case. Rotating diametrical mode in the vaneless gap and standing wave in the spiral case are identified. The influence of the resonance on phase and amplitude of pressure fluctuations obtained for both the spiral case and the vaneless gap is analyzed. The mode shape and frequencies are confirmed using eigenvalues analysis.

Nicolet, C.; Ruchonnet, N.; Alligné, S.; Koutnik, J.; Avellan, F.

2010-08-01

199

PSP Measurement of Stator Vane Surface Pressures in a High Speed Fan  

NASA Technical Reports Server (NTRS)

This paper presents measurements of static pressures on the stator vane suction side of a high-speed single stage fan using the technique of pressure sensitive paint (PSP). The paper illustrates development in application of the relatively new experimental technique to the complex environment of internal flows in turbomachines. First, there is a short explanation of the physics of the PSP technique and a discussion of calibration methods for pressure sensitive paint in the turbomachinery environment. A description of the image conversion process follows. The recorded image of the stator vane pressure field is skewed due to the limited optical access and must be converted to the meridional plane projection for comparison with analytical predictions. The experimental results for seven operating conditions along an off-design rotational speed line are shown in a concise form, including performance map points, mindspan static tap pressure distributions, and vane suction side pressure fields. Then, a comparison between static tap and pressure sensitive paint data is discussed. Finally, the paper lists shortcomings of the pressure sensitive paint technology and lessons learned in this high-speed fan application.

Lepicovsky, Jan

1998-01-01

200

Investigation of the fluid flow in an isolated rotor-stator system with a peripheral opening  

NASA Astrophysics Data System (ADS)

This paper deals with an experimental, theoretical and numerical study of a turbulent flow with separated boundary layers between a rotor and a stator. The system is not subjected to any superimposed radial flow. The periphery of the cavity is opened to the atmosphere so that the solid body rotation for infinite discs is not always observed. Emphasis was placed on development of an asymptotic approach and a step-by-step method to compute the radial distribution of the core swirl ratio and the static pressure on the stator side. The theory also includes the radial and axial velocities in the core region. The numerical simulation has been conducted with the commercial CFD code Fluent 6.1. The k- ?SST turbulence model is used, with the assumption of 2D-axisymmetric and steady flow. CFD validations have been performed by comparison of the numerical results with the corresponding theoretical results. Numerical and experimental results are in good agreement with analytical solutions.

Debuchy, Roger; Abdel Nour, Fadi; Naji, Hassane; Bois, Gérard

2013-04-01

201

Coupling of Low Speed Fan Stator Vane Unsteady Pressures to Duct Modes: Measured versus Predicted  

NASA Technical Reports Server (NTRS)

Uniform-flow annular-duct Green's functions are the essential elements of the classical acoustic analogy approach to the problem of computing the noise generated by rotor-stator interaction inside the fan duct. This paper investigates the accuracy of this class of Green's functions for predicting the duct noise levels when measured stator vane unsteady surface pressures are used as input to the theoretical formulation. The accuracy of the method is evaluated by comparing the predicted and measured acoustic power levels for the NASA 48 inch low speed Active Noise Control Fan. The unsteady surface pressures are measured,by an array of microphones imbedded in the suction and pressure sides of a single vane, while the duct mode levels are measured using a rotating rake system installed in the inlet and exhaust sections of the fan duct. The predicted levels are computed using properly weighted integrals of measured surface pressure distribution. The data-theory comparisons are generally quite good particularly when the mode cut-off criterion is carefully interpreted. This suggests that, at least for low speed fans, the uniform-flow annular-duct Green's function theory can be reliably used for prediction of duct mode levels if the cascade surface pressure distribution is accurately known.

Sutliff, Daniel L.; Heidelberg, Laurence J.; Envia, Edmane

1999-01-01

202

Measurement of the temperature of a stator winding with fiber-optic sensors in bench tests of a turbogenerator  

SciTech Connect

The temperature of the elementary conductors of the stator winding of a 225 MW turbogenerator has been measured using miniature fiber-optic sensors, built in to the winding during manufacture. This is the first time that practical bench tests have been made in Russian electrical machine construction practice. The results of the experiment are used as the initial data for determining important parameters of the construction of turbogenerators with air cooling, namely, the thermal conductivity of the body insulation in the slot, and the heat-transfer coefficient in the front parts of the stator winding.

Gurevich, E. I., E-mail: gur_v@rambler.ru [St. Petersburg State Polytechnic University (Russian Federation); Lyamin, A. A. ['Electrosila' branch of JSC 'Power Machines' (Russian Federation); Shelemba, I. S. [Company 'Inversiya-Sensor' (Russian Federation)

2010-09-15

203

The new diagnosis method of rotor winding inter-turn short circuit fault and imbalance fault based on stator and rotor vibration characteristics  

Microsoft Academic Search

Stator and rotor vibration characteristics of generator are analyzed when the rotor winding inter-turn short circuit fault and the imbalance fault occur. The rotor vibration of fundamental frequency increases and the stator vibration of second frequency decreases when the rotor winding inter-turn short circuit fault occurs. But when the imbalance fault occurs, the rotor vibration of fundamental frequency increases and

Wan Shuting; Li Yonggang; Li Heming; Tang Guiji

2005-01-01

204

Cold-Air Performance of Free Power Turbine Designed for 112-Kilowatt Automotive Gas-Turbine Engine. III. Effect of Stator-Vane End Clearances on Performance.  

National Technical Information Service (NTIS)

An experimental investigation of a free power turbine designed for a 112-kW, automotive, gas-turbine engine was made to determine the penalty in performance due to the stator-vane end clearances. Tests were made over a range of mean section stator-vane an...

M. G. Kofskey, K. L. McLallin

1978-01-01

205

Cold-Air Performance of Free Power Turbine Designed for 112-Kilowatt Automotive Gas-Turbine Engine 3: Effect of Stator Vane End Clearances on Performance.  

National Technical Information Service (NTIS)

An experimental investigation of a free power turbine designed for a 112-kW, automotive, gas turbine engine was made to determine the penalty in performance due to the stator vane end clearances. Tests were made over a range of mean section stator vane an...

M. G. Kofskey, K. L. Mclallin

1978-01-01

206

Winding Configurations and Optimal Stator and Rotor Pole Combination of Flux-Switching PM Brushless AC Machines  

Microsoft Academic Search

A simple analytical method is developed to compare the combinations of stator and rotor pole numbers in flux-switching permanent magnet (PM) machines in terms of back electromotive force (EMF) and electromagnetic torque. The winding connections and winding factors of machines having all poles and alternate poles wound, and different numbers of phases, from two to six, are determined by the

J. T. Chen; Z. Q. Zhu

2010-01-01

207

3D FEA based feature investigation of a claw pole alternator with DC excitation in the stator  

Microsoft Academic Search

This paper deals with finite element analysis (FEA) modeling and features investigation of a claw pole alternator with its DC-excitation winding is located in the stator rather than in the rotor in conventional machines. The proposed model takes into account for the saturation of the magnetic circuit. A special attention is paid to the distribution of the air gap flux

Amina Ibala; Ahmed Masmoudi

2010-01-01

208

Detection of birdcaging in steel wire rope of a hoisting winch system by analysis of load torque and stator current  

Microsoft Academic Search

The aim of this paper is to analyze theoretically and experimentally the stator current of a three phase induction machine and load torque signals in a hoisting winch system, in order to show how they are influenced by the wire rope faulty condition. When the wire rope is subjected to axial and torsional loads, the outer strands can separate from

H. Henao; S. M. J. Rastegar Fatemi; S. Sieg-Zieba; G. A. Capolino

2009-01-01

209

A threaded wobble motor with a 6-pole stator-a micro motor generating large linear displacement  

Microsoft Academic Search

This paper deals with the driving principle and the experimental demonstration of a micro motor which can convert rotation into linear motion and generate large displacement. The motor is a wobble type one; its rotor and stators have screw threads. When the rotor turns, it moves linearly in the axial direction like a screw. The range of linear motion is

Tetsuhiko Iizuka; Hiroyuki Fujita

1996-01-01

210

Acoustic Scattering by Three-Dimensional Stators and Rotors Using the SOURCE3D Code. Volume 2; Scattering Plots  

NASA Technical Reports Server (NTRS)

This second volume of Acoustic Scattering by Three-Dimensional Stators and Rotors Using the SOURCE3D Code provides the scattering plots referenced by Volume 1. There are 648 plots. Half are for the 8750 rpm "high speed" operating condition and the other half are for the 7031 rpm "mid speed" operating condition.

Meyer, Harold D.

1999-01-01

211

An evaluation of alternative stator lamination materials for a high-speed, 1.5 MW, permanent magnet generator  

Microsoft Academic Search

The influence of the choice of stator lamination material on the iron loss in a high speed, high power permanent magnet generator, which is interfaced to a DC link via a simple bridge rectifier, is investigated. The rating of the generator is representative of machines which would be employed in 'more-electric' ships and for embedded power generation. It is shown

Johannes J. H. Paulides; Geraint W. Jewell; David Howe

2004-01-01

212

Core compressor exit stage study. Volume 5: Design and performance report for the Rotor C/Stator B configuration  

NASA Technical Reports Server (NTRS)

Rear stage blading designs that have lower losses in their endwall boundary layer regions were developed. The design of rotor-C and the performance results for rotor-C running with stator B are described. A low speed research compressor is utilized as the principal investigative tool. Four identical stages of blading are used to obtained data in a true multistage environment.

Wisler, D. C.

1981-01-01

213

The design and manufacture of high voltage stator windings for hydro-generators for onerous pumped storage service  

Microsoft Academic Search

The present paper is intended to highlight the approach taken by one major UK OEM in developing, designing and manufacturing high voltage hydrogenerator stator windings for use under the most arduous pumped storage operating conditions. The original concepts were developed in the early 1970s to meet a specific market requirement for some 16 kV hydrogenerators. During the next 10 years

H. S. McNaughton

1995-01-01

214

Investigation on Stator Circulating Current Characteristics of Turbogenerators under Air Gap Eccentricity and Rotor Short-circuit Composite Faults  

Microsoft Academic Search

This article investigates the characteristics of the stator winding parallel branches circulating the current of turbogenerators under air gap eccentricity and rotor inter-turn short-circuit composite faults. The presented current characteristics are achieved from the theoretical derivation of the electromotive force difference between two parallel branches and are verified by the experimental results. Three types of the composite faults are studied.

Shuting Wan; Yuling He; Guiji Tang; Yonggang Li

2010-01-01

215

Analysis of the performance of permanent magnetic stepping motor with trapezoid stator tooth  

NASA Astrophysics Data System (ADS)

With the rapid development of automation techniques, the claw-poled stepping motors are widely used, especially in optical scanners. Most research on stepping motors has concentrated on electrical properties, but a few papers have reported on the performance in relation to the magnetic-field distribution. The purpose of this study is to analyze the effect of the shape of the stator tooth and to search for the optimal parameters using a magnetic-circuit simulation technique. Through numerical calculations, the optimal performance conditions can be obtained by varying the ratio between the two bases of the trapezoid teeth between 1/5 and 1/3, and varying the ratio between the heights of individual teeth in relation to the separation between the two yokes from 11/15 to 13/15.

Liu, C. P.; Li, Y. C.; Liu, K. H.; Wu, K. T.; Yao, Y. D.

2006-04-01

216

Pressure-temperature phase diagram of the rotor-stator compound C 60-cubane  

NASA Astrophysics Data System (ADS)

When the rotor-stator compound C 60?C 8H 8 is treated at temperatures above about 450 K under high-pressure conditions, fullerene-based copolymers are formed. Earlier results have shown the existence of two types of polymers, a "low-pressure" pseudo-cubic copolymer similar to that formed at atmospheric pressure, and a "high-pressure" phase tentatively identified as a pseudo-orthorhombic copolymer structurally based on the known low-temperature phase. In this communication we show that the reaction boundary between the polymers occurs at pressures near 1 GPa. From this result it follows that the slope of the cubic-orthorhombic phase line in the pristine material is 305 K GPa -1, significantly larger than the slope observed for the corresponding rotational transition in pure C 60.

Iwasiewicz-Wabnig, A.; Röding, R.; Sundqvist, B.; Kováts, É.; Jalsovszky, I.; Pekker, S.

2007-07-01

217

Performance of radial clearance rim seals in upstream and downstream rotor-stator wheelspaces  

NASA Astrophysics Data System (ADS)

A new experimental facility for the investigation of rim sealing is described, and measurements are presented for two representative radial clearance seals with a nominally axisymmetric external flow. One radial seal has an upward rotor lip and is upstream of the rotor while the other has an upward stator lip and is downstream of the rotor. Measurements include surface pressures, tangential velocities in the core region of the disk cavity flow, and traverses of gas concentration in the cavity showing the distribution of mainstream ingestion. Tests were conducted at rotational Reynolds numbers up to 3 x 10 exp 6 with nominal seal clearance to radius ratios in the range 0.002 to 0.01. For the radial seals, a differential pressure criterion is found to overestimate the minimum sealing flow. Tangential velocity measurements in the wheelspace are in excellent agreement with other measurements and theoretical predictions.

Dadkhan, S.; Turner, A. B.; Chew, J. W.

1991-06-01

218

Flagella stator homologs function as motors for myxobacterial gliding motility by moving in helical trajectories  

PubMed Central

Many bacterial species use gliding motility in natural habitats because external flagella function poorly on hard surfaces. However, the mechanism(s) of gliding remain elusive because surface motility structures are not apparent. Here, we characterized the dynamics of the Myxococcus xanthus gliding motor protein AglR, a homolog of the Escherichia coli flagella stator protein MotA. We observed that AglR decorated a helical structure, and the AglR helices rotated when cells were suspended in liquid or when cells moved on agar surfaces. With photoactivatable localization microscopy, we found that single molecules of AglR, unlike MotA/MotB, can move laterally within the membrane in helical trajectories. AglR slowed down transiently at gliding surfaces, accumulating in clusters. Our work shows that the untethered gliding motors of M. xanthus, by moving within the membrane, can transform helical motion into linear driving forces that push against the surface.

Nan, Beiyan; Bandaria, Jigar N.; Moghtaderi, Amirpasha; Sun, Im-Hong; Yildiz, Ahmet; Zusman, David R.

2013-01-01

219

An explicit Runge-Kutta method for unsteady rotor/stator interaction  

NASA Technical Reports Server (NTRS)

A quasi-three-dimensional rotor/stator analysis has been developed for blade-to-blade flows in turbomachinery. The analysis solves the unsteady Euler or thin-layer Navier-Stokes equations in a body-fitted coordinate system. It accounts for the effects of rotation, radius change, and stream-surface thickness. The Baldwin-Lomax eddy-viscosity model is used for turbulent flows. The equations are integrated in time using a four-stage Runge-Kutta scheme with a constant timestep. Results are shown for the first stage of the Space Shuttle Main Engine high pressure fuel turbopump. Euler and Navier-Stokes results are compared on the scaled single- and multi-passage machine. The method is relatively fast and the quasi-three-dimensional formulation is applicable to a wide range of turbomachinery geometries.

Jorgenson, Philip C. E.; Chima, Rodrick V.

1988-01-01

220

EEMD-based wind turbine bearing failure detection using the generator stator current homopolar component  

NASA Astrophysics Data System (ADS)

Failure detection has always been a demanding task in the electrical machines community; it has become more challenging in wind energy conversion systems because sustainability and viability of wind farms are highly dependent on the reduction of the operational and maintenance costs. Indeed the most efficient way of reducing these costs would be to continuously monitor the condition of these systems. This allows for early detection of the generator health degeneration, facilitating a proactive response, minimizing downtime, and maximizing productivity. This paper provides then an assessment of a failure detection techniques based on the homopolar component of the generator stator current and attempts to highlight the use of the ensemble empirical mode decomposition as a tool for failure detection in wind turbine generators for stationary and non-stationary cases.

Amirat, Yassine; Choqueuse, Vincent; Benbouzid, Mohamed

2013-12-01

221

Loss measurement and analysis for the prototype generator with HTS stator and permanent magnet rotor  

NASA Astrophysics Data System (ADS)

A prototype HTS synchronous generator with a permanent magnet rotor and HTS armature windings was developed. The rated armature frequency is 10 Hz. The cryogenic Dewar is tightly surrounded outside the iron core. Both HTS coils and the iron core were cooled by using conduction cooling method. During the process of no-load running, the no-load loss power data were obtained through the torque measurement. The temperature evolution characteristics of the stator was measured by PT-100 temperature sensors. These results show that the no-load loss power at around 77 K are much larger than that at room temperature. The possible reason for the no-load loss increment is discussed. The ac loss power of one individual HTS coil used in this generator was also tested. Compared with the iron loss power, the ac loss power is rather small and could be neglected.

Song, Peng; Qu, Timing; Yu, Xiaoyu; Li, Longnian; Gu, Chen; Li, Xiaohang; Wang, Dewen; Hu, Boping; Chen, Duxing; Han, Zhenghe

2013-11-01

222

Study of stator-vane fluctuating pressures in a turbofan engine for static and flight tests  

NASA Technical Reports Server (NTRS)

As part of a program to study the fan noise generated from turbofan engines, fluctuating surface pressures induced by fan-rotor wakes were measured on core- and bypass-stator outlet guide vanes of a modified JT15D-1 engine. Tests were conducted with the engine operating on an outdoor test stand and in flight. The amplitudes of pressures measured at fan-rotor blade-passage fundamental frequencies were generally higher and appeared less stable for the static tests than for the flight tests. Fluctuating pressures measured at the blade-passage frequency of the high-speed core compressor were interpreted to be acoustic; however, disturbance trace velocities for either the convected rotor wakes or acoustic pressures were difficult to interpret because of the complex environment.

Mueller, A. W.

1984-01-01

223

Modeling and Simulating of Single Side Short Stator Linear Induction Motor with the End Effect  

NASA Astrophysics Data System (ADS)

Linear induction motors are under development for a variety of demanding applications including high speed ground transportation and specific industrial applications. These applications require machines that can produce large forces, operate at high speeds, and can be controlled precisely to meet performance requirements. The design and implementation of these systems require fast and accurate techniques for performing system simulation and control system design. In this paper, a mathematical model for a single side short stator linear induction motor with a consideration of the end effects is presented; and to study the dynamic performance of this linear motor, MATLAB/SIMULINK based simulations are carried out, and finally, the experimental results are compared to simulation results.

Hamzehbahmani, Hamed

2011-09-01

224

BRIEF COMMUNICATION: Piezoelectric ultrasonic resonant motor with stator diameter less than 250 µm: the Proteus motor  

NASA Astrophysics Data System (ADS)

Minimally invasive and in vivo surgery is limited by the ability to provide controllable and powerful motion at scales appropriate for navigation within the human body. A motor for in vivo microbot propulsion is presented with a stator diameter of phi250 µm, demonstrating the potential to directly drive a flagellum for swimming at up to 1295 rpm with a torque of 13 nN m. The motor uses coupled axial-torsional vibration at 652-682 kHz in a helically cut structure excited by a thickness-polarized piezoelectric element. The output power is 4.25 µW, on the order of what is necessary to navigate small human arteries.

Watson, B.; Friend, J.; Yeo, L.

2009-02-01

225

Heat transfer measurements in an opened rotor-stator system air-gap  

SciTech Connect

This article presents an experimental study of the heat transfers in a discoidal rotor-stator system air-gap. Measurements are performed over the rotor, using an experimental technique based on infrared thermography, in order to determine the surface temperatures. Using a thermal balance, the local convective heat transfer coefficient is identified. The influences of the rotational Reynolds number Re and the dimensionless spacing between the two disks G are carried out and compared with literature data when available. Local convective heat transfer coefficients are obtained for Re ranging from 1.29x10{sup 5} to 6.45x10{sup 5} and for G between 0.01 and 0.16. Four heat transfer regimes are identified then correlated. Comparisons with our previous results concerning flow and heat transfers over a single rotating disk in still air are also carried out. (author)

Pelle, Julien; Harmand, Souad [Laboratoire de Mecanique et Energetique, Universite de Valenciennes et du Hainaut-Cambresis, Le Mont Houy, 59313 Valenciennes Cedex 9 (France)

2007-01-15

226

Thermal stress analysis and design of the stator of a 300 MVA superconducting generator  

SciTech Connect

This paper presents the results for an axisymmetric finite element analysis of the stator armature and flux shield of a 300 MVA superconducting generator subject to manufacturing and operational thermal events. These machines typically will have large air gap armatures, departing from conventional generator experience. The mechanical design of such an armature to withstand operational loads is a new area. Key stresses are determined in the structure, especially interlaminar tensile stresses in the insulating skins and conductors, and compressive and tensile stresses along the axes of the armature conductors. Recommendations are made for further investigations. This work was performed as part of a joint effort with the Electric Power Research Institute to design a 300 MVA superconducting generator.

Nathenson, R.D.; Cherepko, J.; Patel, M.R.

1986-09-01

227

A kinematical/numerical analysis of rotor-stator interaction noise  

NASA Technical Reports Server (NTRS)

In this study, the unsteady, thin-layer Navier-Stokes equations are solved using a system of patched grids for a rotor-stator configuration of an axial turbine. The study examines the plurality of spinning modes that are present in such an interaction. The propagation of these modes is analyzed and appropriate grid spacing chosen in the far upstream and downstream regions to attenuate reflections from the computational boundaries. In addition, radiating boundary conditions are implemented based on the farfield acoustical behavior of the flow field. Results in the form of pressure amplitudes and the spectra of turbine tones are presented. Numerical results and experimental data are compared wherever possible. The numerical results are also shown to conform with the predictions of a kinematical analysis of the flowfield.

Rangwalla, Akil A.; Rai, Man Mohan

1990-01-01

228

A numerical analysis of tonal acoustics in rotor-stator interactions  

NASA Technical Reports Server (NTRS)

In this study, the unsteady, thin-layer, Navier-Stokes equations are solved using a system of patched grids for a rotor-stator configuration of an axial turbine. The study focuses on the plurality of spinning modes that are present in such an interaction. The propagation of these modes in the upstream and downstream regions is analyzed and compared with numerical results. It was found that the numerically calculated tonal acoustics could be affected by the type of numerical boundary conditions employed at the inlet and exit of the computational boundaries and the grid spacing in the upstream and downstream regions. Results in the form of surface pressure amplitudes and the spectra of turbine tones and their far field behavior are presented. Numerical results and experimental data are compared wherever possible. The 'mode-content' for different harmonics of blade-passage frequency is shown to conform with that predicted by a kinematical analysis.

Rangwalla, A. A.; Rai, M. M.

1993-01-01

229

Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines  

NASA Technical Reports Server (NTRS)

A new, deadbeat type of direct torque control is proposed, analyzed and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

Kenny, Barbara H.; Lorenz, Robert D.

2003-01-01

230

Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines. Revision 1  

NASA Technical Reports Server (NTRS)

A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

Kenny, Barbara H.; Lorenz, Robert D.

2002-01-01

231

Stator and Rotor Flux Based Deadbeat Direct Torque Control of Induction Machines  

NASA Technical Reports Server (NTRS)

A new, deadbeat type of direct torque control is proposed, analyzed, and experimentally verified in this paper. The control is based on stator and rotor flux as state variables. This choice of state variables allows a graphical representation which is transparent and insightful. The graphical solution shows the effects of realistic considerations such as voltage and current limits. A position and speed sensorless implementation of the control, based on the self-sensing signal injection technique, is also demonstrated experimentally for low speed operation. The paper first develops the new, deadbeat DTC methodology and graphical representation of the new algorithm. It then evaluates feasibility via simulation and experimentally demonstrates performance of the new method with a laboratory prototype including the sensorless methods.

Kenny, Barbara H.; Lorenz, Robert D.

2001-01-01

232

Fault diagnosis of motor drives using stator current signal analysis based on dynamic time warping  

NASA Astrophysics Data System (ADS)

Electrical motor stator current signals have been widely used to monitor the condition of induction machines and their downstream mechanical equipment. The key technique used for current signal analysis is based on Fourier transform (FT) to extract weak fault sideband components from signals predominated with supply frequency component and its higher order harmonics. However, the FT based method has limitations such as spectral leakage and aliasing, leading to significant errors in estimating the sideband components. Therefore, this paper presents the use of dynamic time warping (DTW) to process the motor current signals for detecting and quantifying common faults in a downstream two-stage reciprocating compressor. DTW is a time domain based method and its algorithm is simple and easy to be embedded into real-time devices. In this study DTW is used to suppress the supply frequency component and highlight the sideband components based on the introduction of a reference signal which has the same frequency component as that of the supply power. Moreover, a sliding window is designed to process the raw signal using DTW frame by frame for effective calculation. Based on the proposed method, the stator current signals measured from the compressor induced with different common faults and under different loads are analysed for fault diagnosis. Results show that DTW based on residual signal analysis through the introduction of a reference signal allows the supply components to be suppressed well so that the fault related sideband components are highlighted for obtaining accurate fault detection and diagnosis results. In particular, the root mean square (RMS) values of the residual signal can indicate the differences between the healthy case and different faults under varying discharge pressures. It provides an effective and easy approach to the analysis of motor current signals for better fault diagnosis of the downstream mechanical equipment of motor drives in the time domain in comparison with conventional FT based methods.

Zhen, D.; Wang, T.; Gu, F.; Ball, A. D.

2013-01-01

233

Protection from ground faults in the stator winding of generators at power plants in the Siberian networks  

SciTech Connect

The experience of many years of experience in developing and utilization of ground fault protection in the stator winding of generators in the Siberian networks is generalized. The main method of protection is to apply a direct current or an alternating current with a frequency of 25 Hz to the primary circuits of the stator. A direct current is applied to turbo generators operating in a unit with a transformer without a resistive coupling to the external grid or to other generators. Applying a 25 Hz control current is appropriate for power generation systems with compensation of a capacitive short circuit current to ground. This method forms the basis for protection of generators operating on busbars, hydroelectric generators with a neutral grounded through an arc-suppression reactor, including in consolidated units with generators operating in parallel on a single low-voltage transformer winding.

Vainshtein, R. A., E-mail: vra@tpu.ru [Tomsk Polytechnical University (Russian Federation); Lapin, V. I. [ODU Sibiri (Integrated Dispatcher Control for Siberia), branch of JSC 'SO EES' (Russian Federation); Naumov, A. M.; Doronin, A. V. [JSC NPP 'EKRA' (Russian Federation); Yudin, S. M. [Tomsk Polytechnical University (Russian Federation)

2010-05-15

234

Effects of stator wakes and spanwise nonuniform inlet conditions on the rotor flow of an axial turbine stage  

SciTech Connect

Detailed measurements have been performed in a subsonic, axial-flow turbine stage to investigate the structure of the secondary flow field and the loss generation. The data include the static pressure distribution on the rotor blade passage surfaces and radial-circumferential measurements of the rotor exit flow field using three-dimensional hot-wire and pneumatic probes. The flow field at the rotor outlet is derived from unsteady hot-wire measurements with high temporal and spatial resolution. The paper presents the formation of the tip clearance vortex and the passage vortices, which are strongly influenced by the spanwise nonuniform stator outlet flow. Taking the experimental values for the unsteady flow velocities and turbulence properties, the effect of the periodic stator wakes on the rotor flow is discussed.

Zeschky, J.; Gallus, H.E. (Institute fuer Strahlantriebe und Turboarbeitsmaschinen, Aachen (Germany))

1993-01-01

235

A wound-field three-phase flux-switching synchronous motor with all excitation sources on the stator  

Microsoft Academic Search

A three-phase, segmental-rotor, flux-switching synchronous motor is presented for the first time, with both field and armature windings placed on the stator. Mutual coupling of the circuits is through segments whose motion causes switching of flux in the armature circuit. The magnetic geometry is substantially different to that of other flux-switching machines, and may offer advantages in terms of torque

Ackim Zulu; Barrie Mecrow; Matthew Armstrong

2009-01-01

236

A Wound-Field Three-Phase Flux-Switching Synchronous Motor With All Excitation Sources on the Stator  

Microsoft Academic Search

A three-phase, segmental-rotor, flux-switching synchronous motor is presented for the first time, with both field and armature windings placed on the stator. Mutual coupling of the circuits is through segments whose motion causes switching of flux in the armature circuit. The magnetic geometry is substantially different to that of other flux-switching machines (FSMs), and may offer advantages in terms of

Ackim Zulu; Barrie C. Mecrow; Matthew Armstrong

2010-01-01

237

Study of epoxy\\/mica insulation deterioration in generator stator using ultra-wide band partial discharge testing technique  

Microsoft Academic Search

The epoxy\\/mica insulation in a generator stator deteriorates under the conditions of thermal, electrical, vibrational and thermo-mechanical stresses when the generator is running. To assess the insulation aging status and to understand the deterioration process, an ultra-wide band partial discharge testing method was adopted in this study. A multi-stress accelerated aging equipment was established to imitate the actual service conditions.

Xiaolin Chen; Yonghong Cheng; Bo Yue; Hengkun Xie

2006-01-01

238

Design and Analyses of a Coreless-Stator-Type Bearingless Motor\\/Generator for Clean Energy Generation and Storage Systems  

Microsoft Academic Search

This paper presents a design for a new bearingless motor\\/generator suitable for use in clean energy generation and storage systems. The machine is an outer-rotor type with a coreless stator. By using this type of bearingless drive in an energy generation or storage system, it is possible to obtain high efficiency, maintenance-free operation, and a long life cycle. In this

M. Ooshima; S. Kitazawa; A. Chiba; T. Fukao; D. G. Dorrell

2006-01-01

239

Unsteady three-dimensional flow in a single-stage transonic fan: Part 2: Unsteady stator exit flow field  

Microsoft Academic Search

Detailed unsteady aerodynamic measurements have been taken in a single-stage transonic fan with a very high stage-hub loading. Two-dimensional dynamic yawmeter probes, capable of measuring mean levels and fluctuations in stagnation pressure, static pressure, and yaw angle have been traversed at rotor exit and downstream of the stator, along with several types of pneumatic three-dimensional probe. Part 1 describes measurements

M. A. Cherrett; J. D. Bryce; R. B. Ginder

1995-01-01

240

Electromagnetic Radial Forces in a Hybrid Eight-Stator-Pole, Six-Rotor-Pole Bearingless Switched-Reluctance Motor  

NASA Technical Reports Server (NTRS)

Analysis and experimental measurement of the electromagnet force loads on the hybrid rotor in a novel bearingless switched-reluctance motor (BSRM) have been performed. A BSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The BSRM has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of stator poles. A second set of stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Analysis was done for nonrotating rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental results and the theoretical predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

2007-01-01

241

Feasibility of Using PZT Actuators to Study the Dynamic Behavior of a Rotating Disk due to Rotor-Stator Interaction.  

PubMed

In this paper, PZT actuators are used to study the dynamic behavior of a rotating disk structure due to rotor-stator interaction excitation. The disk is studied with two different surrounding fluids-air and water. The study has been performed analytically and validated experimentally. For the theoretical analysis, the natural frequencies and the associated mode shapes of the rotating disk in air and water are obtained with the Kirchhoff-Love thin plate theory coupled with the interaction with the surrounding fluid. A model for the Rotor Stator Interaction that occurs in many rotating disk-like parts of turbomachinery such as compressors, hydraulic runners or alternators is presented. The dynamic behavior of the rotating disk due to this excitation is deduced. For the experimental analysis a test rig has been developed. It consists of a stainless steel disk (r = 198 mm and h = 8 mm) connected to a variable speed motor. Excitation and response are measured from the rotating system. For the rotating excitation four piezoelectric patches have been used. Calibrating the piezoelectric patches in amplitude and phase, different rotating excitation patterns are applied on the rotating disk in air and in water. Results show the feasibility of using PZT to control the response of the disk due to a rotor-stator interaction. PMID:25004151

Presas, Alexandre; Egusquiza, Eduard; Valero, Carme; Valentin, David; Seidel, Ulrich

2014-01-01

242

Direct Torque Control with Full Order Stator Flux Observer for Dual-Three Phase Induction Motor Drives  

NASA Astrophysics Data System (ADS)

A Direct Torque Control (DTC) strategy for dual-three phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. To improve the flux estimation, an Adaptive Stator Flux Observer (ASFO) has been used. Doing so, besides a better flux estimation in contrast to open-loop flux estimators, it is possible to use the observed currents to compensate the inverter non-linear behavior (such as dead-time effects), improving the drive performance at low speed. This is particularly important for low voltage/high current applications, as the drive considered in this paper. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Experimental results are presented for a 10kW dual three-phase induction motor drive prototype.

Farina, Francesco; Bojoi, Radu; Tenconi, Alberto; Profumo, Francesco

243

Polymerization of the rotor-stator compound C60 -cubane under pressure  

NASA Astrophysics Data System (ADS)

Cubane, C8H8 , can be inserted into the octahedral voids of fullerene lattices to create a family of rotor-stator compounds. We have investigated the structural phase behavior of C60•C8H8 by annealing a number of samples for up to 3h at selected temperatures in the range 380-870K under pressures up to 2GPa . The high-pressure treated materials were then investigated under ambient conditions using Raman spectroscopy and x-ray diffraction. C60•C8H8 is found to have at least five different structural phases depending on treatment conditions. In addition to the known cubic and orthorhombic structures observed at atmospheric pressure, we find two polymeric states with pseudocubic and pseudoorthorhombic structures, respectively, based on the two original lattices and created by heating in different pressure ranges. These materials are believed to be copolymers of C60 and decomposition products of cubane. In contrast to the polymeric states of C60 the present polymer structures are determined by the topology of the original lattices rather than by the molecular structure. Above 700K we find a carbon-rich amorphous state created when the cubane finally decomposes, releasing its hydrogen content in the form of hydrocarbons.

Iwasiewicz-Wabnig, A.; Sundqvist, B.; Kováts, É.; Jalsovszky, I.; Pekker, S.

2007-01-01

244

Ecological and evolutionary diversification of the seed beetle genus Stator (Coleoptera: Chrysomelidae: Bruchinae).  

PubMed

Ehrlich and Raven's (1964) hypothesis on coevolution has stimulated numerous phylogenetic studies that focus on the effects of plant defensive chemistry as the main ecological axis of phytophagous insect diversification. However, other ecological features affect host use and diet breadth and they may have very different consequences for insect evolution. In this paper, we present a phylogenetic study based on DNA sequences from mitochondrial and protein-coding genes of species in the seed beetle genus Stator, which collectively show considerable interspecific variation in host affiliation, diet breadth, and the dispersal stage of the seeds that they attack. We used comparative analyses to examine transitions in these three axes of resource use. We argue that these analyses show that diet breadth evolution is dependent upon colonizing novel hosts that are closely or distantly related to the ancestral host, and that oviposition substrate affects the evolution of host-plant affiliation, the evolution of dietary specialization, and the degree to which host plants are shared between species. The results of this study show that diversification is structured by interactions between different selective pressures and along multiple ecological axes. PMID:16050108

Morse, Geoffrey E; Farrell, Brian D

2005-06-01

245

Compressible simulation of rotor-stator interaction in pump-turbines  

NASA Astrophysics Data System (ADS)

This work investigates the influence of water compressibility on pressure pulsations induced by rotor-stator interaction (RSI) in hydraulic machinery, using the commercial CFD solver ANSYS-CFX. A pipe flow example with harmonic velocity excitation at the inlet plane is simulated using different grid densities and time step sizes. Results are compared with a validated code for hydraulic networks (SIMSEN). Subsequently, the solution procedure is applied to a simplified 2.5-dimensional pump-turbine configuration in model scale with an adapted speed of sound. Pressure fluctuations are compared with numerical and experimental data based on prototype scale. The good agreement indicates that the scaling of acoustic effects with an adapted speed of sound works well. Finally, the procedure is applied to a 3-dimensional pump configuration in model scale. Pressure fluctuations are compared with results from prototype measurements. Compared to incompressible computations, compressible simulations provide similar pressure fluctuations in vaneless space, but pressure fluctuations in spiral case and penstock may be much higher. With respect to pressure fluctuation amplitudes along the centerline of runner channels, incompressible solutions exhibit a linear decrease while compressible solutions exhibit sinusoidal distributions with maximum values at half the channel length, coinciding with analytical solutions of one-dimensional acoustics.

Yan, J.; Koutnik, J.; Seidel, U.; Hübner, B.

2010-08-01

246

Periodic transition on an axial compressor stator: Incidence and clocking effects. Part 2: Transition onset predictions  

SciTech Connect

Transition onset observations from a 1.5-stage axial compressor outlet stator presented in Part 1 of this paper are compared with the predictions of conventional transition correlations applied in a quasi-steady manner. The viscous/inviscid interaction code MISES is used to predict the blade surface pressure distributions, and boundary layer development. The temporal variation in transition onset is then predicted using ensemble-averaged free-stream turbulence data from the compressor measurements. This simple procedure captures most significant features of the complex transition process on the compressor, and is clearly superior to fixed transition models based on long-term average free-stream turbulence levels. Parallel computations for both natural and bypass transition modes indicate that the natural transition mode tends to dominate on the compressor. This is at variance with turbine airfoil experience, where bypass transition is clearly more important. Comparison of prediction and experiment highlights the significance of leading edge potential flow interactions in promoting periodic wake-induced transition. Viscous/inviscid interactions in the neighborhood of transition can also have an important influence on boundary layer stability and separation phenomena.

Solomon, W.J. [General Electric Aircraft Engines, Cincinnati, OH (United States); Walker, G.J.; Hughes, J.D. [Univ. of Tasmania, Hobart (Australia). School of Engineering

1999-07-01

247

Rotor-stator contact dynamics using a non-ideal drive—Theoretical and experimental aspects  

NASA Astrophysics Data System (ADS)

The possible contact between rotor and stator is considered a serious malfunction that may lead to catastrophic failure. Rotor rub is seen as a secondary phenomenon caused by a primary source, i.e. sudden mass unbalance, instabilities generated by aerodynamic and hydrodynamic forces in seals and bearings among others. The contact event gives rise to normal and friction forces exerted on the rotor at impact events. The friction force plays a significant role by transferring some rotational energy of the rotor to lateral motion. A mathematical model has been developed to capture this for a conventional backup annular guide setup. It is reasonable to superpose an impact condition to the rub, where the rotor spin energy can be fully transformed into rotor lateral movements. Using a nonideal drive, i.e. an electric motor without any kind of velocity feedback control, it is even possible to stop the rotor spin under rubbing conditions. All the rotational energy will be transformed in a kind of "self-excited" rotor lateral vibration with repeated impacts against the housing. This paper studies the impact motion of a rotor impacting a conventional backup annular guide for the case of dry and lubricated inner surface of the guide. For the dry surface case, the experimental and numerical analysis shows that the rotational energy is fully transformed into lateral motion and the rotor spin is stopped. Based on this study this paper proposes a new unconventional backup bearing design in order to reduce the rub related severity in friction and center the rotor at impact events. The analysis shows that the rotor at impacts is forced to the center of the backup bearing and the lateral motion is mitigated. As a result of this, the rotor spin is kept constant.

Lahriri, Said; Weber, Hans I.; Santos, Ilmar F.; Hartmann, Henning

2012-09-01

248

Properties of Motility in Bacillus subtilis Powered by the H+- Coupled MotAB Flagellar Stator, Na+-Coupled MotPS or Hybrid Stators MotAS or MotPB  

PubMed Central

Bacillus subtilis has a single set of flagellar rotor proteins that interact with two distinct stator-force generators, the H+-coupled MotAB complex and the Na+-coupled MotPS complex, that energize rotation. Here, motility on soft agar plates and in liquid was assayed in wild-type B. subtilis and strains expressing only one stator, either MotAB, MotPS or hybrid MotAS or MotPB. The strains expressing MotAB or MotAS had an average of 11 flagella/cell while those expressing MotPS or MotPB had an average of 7 flagella/cell, while a Mot-less double mutant had 3-4 flagella/cell. MotAB had a more dominant role in motility than MotPS under most conditions, but MotPS supported comparable motility to MotAB on malate-containing soft agar plating media at elevated pH and Na+. MotAB supported much faster swimming speeds in liquid than MotPS, MotAS or MotPB under all conditions, but a contribution of MotPS to wild-type swimming was discernible from differences in swimming speeds of wild-type and MotAB at elevated viscosity, pH and Na+. Swimming supported by MotPS and MotAS was stimulated by Na+ and elevated pH whereas the converse was true of MotAB and MotPB. This suggests that MotAS is Na+-coupled and MotPB is H+-coupled and that MotB and MotS are major determinants of ion-coupling. However, the swimming speed supported by MotPB, as well as MotPS and MotAS, was inhibited severely at Na+ concentrations above 300 mM whereas MotAB-dependent swimming was not. The presence of either the MotP or MotS component in the stator also conferred sensitivity to inhibition by an amiloride analogue. These observations suggest that MotP contributes to Na+-coupling and inhibition by Na+ channel inhibitors. Similarly, a role for MotA in H+-dependent stator properties is indicated by the larger effects of pH on the Na+-response of MotAS vs MotPS. Finally, optimal function at elevated viscosity was found only in MotPS and MotPB and is therefore conferred by MotP.

Ito, Masahiro; Terahara, Naoya; Fujinami, Shun; Krulwich, Terry Ann

2008-01-01

249

Properties of motility in Bacillus subtilis powered by the H+-coupled MotAB flagellar stator, Na+-coupled MotPS or hybrid stators MotAS or MotPB.  

PubMed

Bacillus subtilis has a single set of flagellar rotor proteins that interact with two distinct stator-force generators, the H+-coupled MotAB complex and the Na+-coupled MotPS complex, that energize rotation. Here, motility on soft agar plates and in liquid was assayed in wild-type B.subtilis and strains expressing only one stator, either MotAB, MotPS or hybrid MotAS or MotPB. The strains expressing MotAB or MotAS had an average of 11 flagella/cell while those expressing MotPS or MotPB had an average of seven flagella/cell, and a Mot-less double mutant had three to four flagella/cell. MotAB had a more dominant role in motility than MotPS under most conditions, but MotPS supported comparable motility to MotAB on malate-containing soft agar plating media at elevated pH and Na+. MotAB supported much faster swimming speeds in liquid than MotPS, MotAS or MotPB under all conditions, but a contribution of MotPS to wild-type swimming was discernible from differences in swimming speeds of wild-type and MotAB at elevated viscosity, pH and Na+. Swimming supported by MotPS and MotAS was stimulated by Na+ and elevated pH whereas the converse was true of MotAB and MotPB. This suggests that MotAS is Na+-coupled and MotPB is H+-coupled and that MotB and MotS are major determinants of ion-coupling. However, the swimming speed supported by MotPB, as well as MotPS and MotAS, was inhibited severely at Na+ concentrations above 300 mM whereas MotAB-dependent swimming was not. The presence of either the MotP or MotS component in the stator also conferred sensitivity to inhibition by an amiloride analogue. These observations suggest that MotP contributes to Na+-coupling and inhibition by Na+ channel inhibitors. Similarly, a role for MotA in H+-dependent stator properties is indicated by the larger effects of pH on the Na+-response of MotAS versus MotPS. Finally, optimal function at elevated viscosity was found only in MotPS and MotPB and is therefore conferred by MotP. PMID:16095621

Ito, Masahiro; Terahara, Naoya; Fujinami, Shun; Krulwich, Terry Ann

2005-09-16

250

Measurements of the unsteady flow field within the stator row of a transonic axial-flow fan. Part 2: Results and discussion  

NASA Technical Reports Server (NTRS)

Unsteady velocity field measurements made within the stator row of a transonic axial-flow fan are presented. Measurements were obtained at midspan for two different stator blade rows using a laser anemometer. The first stator row consists of double circular-arc airfoils with a solidity of 1.68. The second features controlled-diffusion airfoils with a solidity of 0.85. Both were tested at design-speed peak efficiency conditions. In addition, the controlled-diffusion stator was also tested at near stall conditions. The procedures developed here are used to identify the rotor wake generated and unresolved unsteadiness from the velocity measurements (rotor wake generated unsteadiness refers to the unsteadiness generated by the rotor wake velocity deficit and unresolved unsteadiness refers to all remaining unsteadiness which contributes to the spread in the distribution of velocities such as vortex shedding, turbulence, etc.). Auto and cross correlations of these unsteady velocity fluctuations are presented to show their relative magnitude and spatial distributions. Amplification and attenuation of both rotor wake generated and unresolved unsteadiness are shown to occur within the stator blade passage.

Hathaway, M. D.; Suder, K. L.; Okiishi, T. H.; Strazisar, A. J.; Adamczyk, J. J.

1987-01-01

251

Comparison of Off-line and On-line Measurement of Partial Discharges for Hydrogenerator Stator Windings using Acoustic Emission Sensors  

NASA Astrophysics Data System (ADS)

The establishment of Condition Based Maintenance for hydrogenerators is very important for monitoring the conditions of stator windings insulation. On-line partial discharge (PD) testing has been used to provide useful information for monitoring the integrity and diagnosing problems in hydrogenerator stator winding insulation. The on-line insulation diagnosis technology can assess thermal, electric, ambient, and mechanical stresses received by the hydrogenerator stator windings. We have already indicated in a previous study that on-line PD measurements using acoustic emission sensor (AE) techniques can be useful for assessing the conditions of stator winding insulation. In this paper, the relationship between AE signals and maximum discharge magnitude was investigated in a non-destructive test for hydrogenerators using off-line measurements. AE signals were investigated by the use of multiple AE sensors, which are produced from an internal discharge for two hydrogenerator stator windings in 11kV and 13.2kV classes, in addition to the load and temperature, and humidity measurements taken on-line in twenty-month and three-month long studies respectively.

Kaneko, Tadamitsu; Ueda, Takashi; Takenouchi, Osamu; Otsubo, Masahisa; Honda, Chikahisa; Tsuruta, Yoshio; Iwamoto, Hideki; Tokumitsu, Akihiro

252

Detection of combined faults in induction machines with stator parallel branches through the DWT of the startup current  

NASA Astrophysics Data System (ADS)

The main objective of this paper is to diagnose the presence of combined faults in induction machines. For this purpose, a methodology based on the application of the Discrete Wavelet Transform (DWT) to the stator startup current is used. This approach was applied in previous works with success to the diagnosis of rotor asymmetries and mixed eccentricities in motors with different sizes and conditions. However, as most of the diagnosis methods hitherto developed, the application of the proposed approach was circumscribed to situations in which a single fault was present in the machine. In addition, the influence of other phenomena such as load torque oscillations or voltage fluctuations was studied, but without considering the combination of these phenomena and the fault in the machine. This work is intended, first, to apply the proposed transient-based methodology to several cases in which different faults (rotor asymmetries, mixed eccentricities and inter-turn and inter-coil stator short-circuits) are simultaneously present in the machine and, second, to apply it to cases regarding faults combined with other phenomena making difficult the diagnosis, such as load torque oscillations. Interesting considerations regarding the preponderance of the effects of some of the faults are also done in the paper. The application of the methodology is focused on induction machines with stator parallel branches; in this sense, the suitability of the use either of the phase current or of the branch current for the diagnosis of each particular fault is analysed. The results look promising with regard to the validity of the methodology for the reliable discrimination of simultaneous electromechanical faults and the diagnosis of faults combined with other phenomena.

Antonino-Daviu, J.; Jover Rodriguez, P.; Riera-Guasp, M.; Pineda-Sánchez, M.; Arkkio, A.

2009-10-01

253

Parameters required to maximize a thermoset hydro-generator stator winding life; Part 1: Design, manufacture, installation  

SciTech Connect

This paper and companion paper, Part 2 describe the parameters required for a thermoset hydro-generator stator winding to achieve a service life of 50 years. Such parameters covering design, manufacture, installation, on-line monitoring and maintenance functions have been found to be relevant based on 36 years of design and operation experience. The database includes North American, European and Far Eastern hydro generators up to 20.5 kV-500 MVA. Parameters covered can be simply stated as Design, Manufacture and Installation: the DIM rule. A companion paper, Part 2 covers Monitoring and Maintenance: which leads to the DIM rule.

Lyles, J.F.; Goodeve, T.E.; Sedding, H.

1994-09-01

254

Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine  

NASA Astrophysics Data System (ADS)

This paper focuses on the experimental investigation of the time-averaged and time-accurate aero-thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the first and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the upstream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of clocking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.

Billiard, N.; Paniagua, Guillermo; Dénos, R.

2008-06-01

255

Broadband Noise of Fans - With Unsteady Coupling Theory to Account for Rotor and Stator Reflection/Transmission Effects  

NASA Technical Reports Server (NTRS)

This report examines the effects on broadband noise generation of unsteady coupling between a rotor and stator in the fan stage of a turbofan engine. Whereas previous acoustic analyses treated the blade rows as isolated cascades, the present work accounts for reflection and transmission effects at both blade rows by tracking the mode and frequency scattering of pressure and vortical waves. The fan stage is modeled in rectilinear geometry to take advantage of a previously existing unsteady cascade theory for 3D perturbation waves and thereby use a realistic 3D turbulence spectrum. In the analysis, it was found that the set of participating modes divides itself naturally into "independent mode subsets" that couple only among themselves and not to the other such subsets. This principle is the basis for the analysis and considerably reduces computational effort. It also provides a simple, accurate scheme for modal averaging for further efficiency. Computed results for a coupled fan stage are compared with calculations for isolated blade rows. It is found that coupling increases downstream noise by 2 to 4 dB. Upstream noise is lower for isolated cascades and is further reduced by including coupling effects. In comparison with test data, the increase in the upstream/downstream differential indicates that broadband noise from turbulent inflow at the stator dominates downstream noise but is not a significant contributor to upstream noise.

Hanson, Donald B.

2001-01-01

256

Prototype and estimation an ultrasonic motor using a transmission rod with a stator vibrator and a rotor at the both ends  

NASA Astrophysics Data System (ADS)

A new structure of ultrasonic motor composed of a stator vibrator, a rotor and an ultrasonic transmission rod is proposed. Two vibrations of a stator vibrator mounted at a rod end excite two orthogonal bending vibrations in the rod and elliptic motions of displacement are formed at another end of the rod. The elliptic motions produce a rotating force to a rotor pressed at the end. The simple structure of mounting and preloading a rotor is designed by FEM. It is checked experimentally that two orthogonal bending vibrations are excited in the rod and the motor operation of the new construction is confirmed.

Takano, Takehiro; Tamura, Hideki; Sato, Daisuke; Aoyagi, Manabu

2012-05-01

257

Cold-air performance of free power turbine designed for 112-kilowatt automotive gas-turbine engine. 2: Effects of variable stator-vane-chord setting angle on turbine performance  

NASA Technical Reports Server (NTRS)

The cold-air performance of an axial-flow power turbine with a variable stator designed for a 112-kW automotive gas-turbine engine was determined at speeds from 30 to 110 percent of design and at pressure ratios from 1.11 to 2.67. Performance is presented in terms of equivalent mass flow, torque, power, and efficiency for stator-vane-chord setting angles of 26 degs, 30 degs, 35 degs (design), 40 degs, 45 degs, and 50 degs. Turbine braking performance at a nominal stator setting angle of 107 degs is also presented. Turbine efficiency increased with increasing stator setting angle. A 10-point efficiency increase was obtained by opening the stator from the design setting angle of 35 degs to a setting angle of 45 degs.

Mclallin, K. L.; Kofskey, M. G.

1979-01-01

258

Reliability and Confidence Interval Analysis of a CMC Turbine Stator Vane  

NASA Technical Reports Server (NTRS)

High temperature ceramic matrix composites (CMC) are being explored as viable candidate materials for hot section gas turbine components. These advanced composites can potentially lead to reduced weight, enable higher operating temperatures requiring less cooling and thus leading to increased engine efficiencies. However, these materials are brittle and show degradation with time at high operating temperatures due to creep as well as cyclic mechanical and thermal loads. In addition, these materials are heterogeneous in their make-up and various factors affect their properties in a specific design environment. Most of these advanced composites involve two- and three-dimensional fiber architectures and require a complex multi-step high temperature processing. Since there are uncertainties associated with each of these in addition to the variability in the constituent material properties, the observed behavior of composite materials exhibits scatter. Traditional material failure analyses employing a deterministic approach, where failure is assumed to occur when some allowable stress level or equivalent stress is exceeded, are not adequate for brittle material component design. Such phenomenological failure theories are reasonably successful when applied to ductile materials such as metals. Analysis of failure in structural components is governed by the observed scatter in strength, stiffness and loading conditions. In such situations, statistical design approaches must be used. Accounting for these phenomena requires a change in philosophy on the design engineer s part that leads to a reduced focus on the use of safety factors in favor of reliability analyses. The reliability approach demands that the design engineer must tolerate a finite risk of unacceptable performance. This risk of unacceptable performance is identified as a component's probability of failure (or alternatively, component reliability). The primary concern of the engineer is minimizing this risk in an economical manner. The methods to accurately determine the service life of an engine component with associated variability have become increasingly difficult. This results, in part, from the complex missions which are now routinely considered during the design process. These missions include large variations of multi-axial stresses and temperatures experienced by critical engine parts. There is a need for a convenient design tool that can accommodate various loading conditions induced by engine operating environments, and material data with their associated uncertainties to estimate the minimum predicted life of a structural component. A probabilistic composite micromechanics technique in combination with woven composite micromechanics, structural analysis and Fast Probability Integration (FPI) techniques has been used to evaluate the maximum stress and its probabilistic distribution in a CMC turbine stator vane. Furthermore, input variables causing scatter are identified and ranked based upon their sensitivity magnitude. Since the measured data for the ceramic matrix composite properties is very limited, obtaining a probabilistic distribution with their corresponding parameters is difficult. In case of limited data, confidence bounds are essential to quantify the uncertainty associated with the distribution. Usually 90 and 95% confidence intervals are computed for material properties. Failure properties are then computed with the confidence bounds. Best estimates and the confidence bounds on the best estimate of the cumulative probability function for R-S (strength - stress) are plotted. The methodologies and the results from these analyses will be discussed in the presentation.

Murthy, Pappu L. N.; Gyekenyesi, John P.; Mital, Subodh K.

2008-01-01

259

Design and testing of swept and leaned outlet guide vanes to reduce stator-strut-splitter aerodynamic flow interactions  

SciTech Connect

Large circumferentially varying pressure levels produced by aerodynamic flow interactions between downstream stators and struts present a potential noise and stability margin liability in a compression component. These interactions are presently controlled by tailoring the camber and/or stagger angles of vanes neighboring the fan frame struts. This paper reports on the design and testing of a unique set of swept and leaned fan outlet guide vanes (OGVs) that do not require this local tailoring even though the OGVs are closely coupled with the fan frame struts and splitter to reduce engine length. The swept and leaned OGVs not only reduce core-duct diffusion, but they also reduce the potential flow interaction between the stator and the strut relative to that produced by conventional radial OGVs. First, the design of the outlet guide vanes using a single blade row three-dimensional viscous flow analysis is outlined. Next, a two-dimensional potential flow analysis was used for the coupled OGV-frame system to obtain a circumferentially nonuniform stator stagger angle distribution to reduce the upstream static pressure disturbance further. Recognizing the limitations of the two-dimensional potential flow analysis for this highly three-dimensional set of leaned OGVs, as a final evaluation of the OGV-strut system design, a full three-dimensional viscous analysis of a periodic circumferential sector of the OGVs, including the fan frame struts and splitter, was performed. The computer model was derived from a NASA-developed code used in simulating the flow field for external aerodynamic applications with complex geometries. The tree-dimensional coupled OGV-frame analysis included the uniformly staggered OGV configuration and the variably staggered OGV configuration determined by the two-dimensional potential flow analysis. Contrary to the two-dimensional calculations, the tree-dimensional analysis revealed significant flow problems with the variable staggered OGV configuration and showed less upstream flow nonuniformity with the uniformly staggered OGV configuration. The flow redistribution in both the radial and tangential directions, captured fully only in the three-dimensional analysis, was identified as the prime contributor to the lower flow nonuniformity with the uniformly staggered OGV configuration. The coupled three-dimensional analysis was also used to validate the design at off-design conditions. Engine test performance and stability measurements with both uniformly and variably staggered OGV configurations with and without the presence of inlet distortion confirmed the conclusions from the three-dimensional analysis.

Wadia, A.R.; Szucs, P.N. [GE Aircraft Engines, Cincinnati, OH (United States); Gundy-Burlet, K.L. [NASA Ames Research Center, Moffet Field, CA (United States)

1999-07-01

260

Unsteady Flows in a Single-Stage Transonic Axial-Flow Fan Stator Row. Ph.D. Thesis - Iowa State Univ.  

NASA Technical Reports Server (NTRS)

Measurements of the unsteady velocity field within the stator row of a transonic axial-flow fan were acquired using a laser anemometer. Measurements were obtained on axisymmetric surfaces located at 10 and 50 percent span from the shroud, with the fan operating at maximum efficiency at design speed. The ensemble-average and variance of the measured velocities are used to identify rotor-wake-generated (deterministic) unsteadiness and turbulence, respectively. Correlations of both deterministic and turbulent velocity fluctuations provide information on the characteristics of unsteady interactions within the stator row. These correlations are derived from the Navier-Stokes equation in a manner similar to deriving the Reynolds stress terms, whereby various averaging operators are used to average the aperiodic, deterministic, and turbulent velocity fluctuations which are known to be present in multistage turbomachines. The correlations of deterministic and turbulent velocity fluctuations throughout the axial fan stator row are presented. In particular, amplification and attenuation of both types of unsteadiness are shown to occur within the stator blade passage.

Hathaway, Michael D.

1986-01-01

261

STUDY OF THE ANGLE OF DEPHASING BETWEEN THE VECTORS OF ROTOR AND STATOR MAGNETIC FLOW IN A SYSTEM OF CONTROL THROUGH ORIENTATION OF A MAGNETIC FIELD  

Microsoft Academic Search

This article presents results received from the study of a system of control of three-phase asynchronous motor through an orientation of a magnetic field. The controller does stabilization of the vector of rotor magnetic flow. The purpose of this study is to find how the angle of dephasing between the vectors of magnetic flows in the rotor and stator changes.

Pencho Georgiev; Dinko Gospodinov

262

Design and analysis of a five-phase interior permanent magnet generator with a non-integer number of stator slots per phase  

Microsoft Academic Search

Traditional electric machine design requiring the balancing of the phases both in phase voltage magnitudes and the angles between adjacent phases informs that the number of stator slots per phase must be an integer. There are situations however, where it is cheaper to use existing laminations for designs with non-integer number of slots per phase to build generators for specialized

Olorunfemi Ojo; Zhiqiao Wu; Sosthenes Karugaba; Adeola Balogun; Emeka Obe

2009-01-01

263

Analysis of a novel stator winding structure minimizing harmonic current and torque ripple for dual six-step converter-fed high power AC machines  

Microsoft Academic Search

The authors study the causes of degraded converter current when dual six-step power converters feed a dual winding induction machine drive. They proposed an end winding structure and corresponding control strategy to solve the converter current problem while retaining the advantages of the dual winding induction machine drive. Principles associated with the stator winding are discussed, and a practical implementation

Lurong Ye; Longya Xu

1993-01-01

264

Roles of Charged Residues in the C-Terminal Region of PomA, a Stator Component of the Na+Driven Flagellar Motor  

Microsoft Academic Search

Bacterial flagellar motors use specific ion gradients to drive their rotation. It has been suggested that the electrostatic interactions between charged residues of the stator and rotor proteins are important for rotation in Escherichia coli. Mutational studies have indicated that the Na-driven motor of Vibrio alginolyticus may incorporate interactions similar to those of the E. coli motor, but the other

Madoka Obara; Toshiharu Yakushi; Seiji Kojima; Michio Homma

2008-01-01

265

Lattice dynamics of a rotor-stator molecular crystal: Fullerene-cubane C60?C8H8  

NASA Astrophysics Data System (ADS)

The dynamics of fullerene-cubane (C60?C8H8) cocrystal is studied combining experimental [x-ray diffuse scattering, quasielastic and inelastic neutron scattering (INS)] and simulation (molecular dynamics) investigations. Neutron scattering gives direct evidence of the free rotation of fullerenes and of the libration of cubanes in the high-temperature phase, validating the “rotor-stator” description of this molecular system. X-ray diffuse scattering shows that orientational disorder survives the order/disorder transition in the low-temperature phase, although the loss of fullerene isotropic rotational diffusion is featured by the appearance of a 2.2 meV mode in the INS spectra. The coupling between INS and simulations allows identifying a degeneracy lift of the cubane librations in the low temperature phase, which is used as a tool for probing the environment of cubane in this phase and for getting further insights into the phase transition mechanism.

Bousige, Colin; Rols, Stéphane; Cambedouzou, Julien; Verberck, Bart; Pekker, Sándor; Kováts, Éva; Durkó, Gábor; Jalsovsky, István; Pellegrini, Éric; Launois, Pascale

2010-11-01

266

Low-Noise Potential of Advanced Fan Stage Stator Vane Designs Verified in NASA Lewis Wind Tunnel Test  

NASA Technical Reports Server (NTRS)

With the advent of new, more stringent noise regulations in the next century, aircraft engine manufacturers are investigating new technologies to make the current generation of aircraft engines as well as the next generation of advanced engines quieter without sacrificing operating performance. A current NASA initiative called the Advanced Subsonic Technology (AST) Program has set as a goal a 6-EPNdB (effective perceived noise) reduction in aircraft engine noise relative to 1992 technology levels by the year 2000. As part of this noise program, and in cooperation with the Allison Engine Company, an advanced, low-noise, high-bypass-ratio fan stage design and several advanced technology stator vane designs were recently tested in NASA Lewis Research Center's 9- by 15-Foot Low-Speed Wind Tunnel (an anechoic facility). The project was called the NASA/Allison Low Noise Fan.

Hughes, Christopher E.

1999-01-01

267

Dual rotor single- stator axial air gap PMSM motor/generator drive for high torque vehicles applications  

NASA Astrophysics Data System (ADS)

The actual e – continuously variable transmission (e-CVT) solution for the parallel Hybrid Electric Vehicle (HEV) requires two electric machines, two inverters, and a planetary gear. A distinct electric generator and a propulsion electric motor, both with full power converters, are typical for a series HEV. In an effort to simplify the planetary-geared e-CVT for the parallel HEV or the series HEV we hereby propose to replace the basically two electric machines and their two power converters by a single, axial-air-gap, electric machine central stator, fed from a single PWM converter with dual frequency voltage output and two independent PM rotors, destined for hybrid electric vehicles (HEV) and military vehicles applications. The proposed topologies and the magneto-motive force analysis are the core of the paper.

Tutelea, L. N.; Deaconu, S. I.; Boldea, I.; Popa, G. N.

2014-03-01

268

Theory for broadband Noise of Rotor and Stator Cascades with Inhomogeneous Inflow Turbulence Including Effects of Lean and Sweep  

NASA Technical Reports Server (NTRS)

The problem of broadband noise generated by turbulence impinging on a downstream blade row is examined from a theoretical viewpoint. Equations are derived for sound power spectra in terms of 3 dimensional wavenumber spectra of the turbulence. Particular attention is given to issues of turbulence inhomogeneity associated with the near field of the rotor and variations through boundary layers. Lean and sweep of the rotor or stator cascade are also handled rigorously with a full derivation of the relevant geometry and definitions of lean and sweep angles. Use of the general theory is illustrated by 2 simple theoretical spectra for homogeneous turbulence. Limited comparisons are made with data from model fans designed by Pratt & Whitney, Allison, and Boeing. Parametric studies for stator noise are presented showing trends with Mach number, vane count, turbulence scale and intensity, lean, and sweep. Two conventions are presented to define lean and sweep. In the "cascade system" lean is a rotation out of its plane and sweep is a rotation of the airfoil in its plane. In the "duct system" lean is the leading edge angle viewing the fan from the front (along the fan axis) and sweep is the angle viewing the fan from the side (,perpendicular to the axis). It is shown that the governing parameter is sweep in the plane of the airfoil (which reduces the chordwise component of Mach number). Lean (out of the plane of the airfoil) has little effect. Rotor noise predictions are compared with duct turbulence/rotor interaction noise data from Boeing and variations, including blade tip sweep and turbulence axial and transverse scales are explored.

Hanson, Donald B.

2001-01-01

269

Aerodynamic performances of three fan stator designs operating with rotor having tip speed of 337 meters per second and pressure ratio of 1.54. Relation of analytical code calculations to experimental performance  

NASA Technical Reports Server (NTRS)

A hub-to-shroud and a blade-to-blade internal-flow analysis code, both inviscid and basically subsonic, were used to calculate the flow parameters within four stator-blade rows. The produced ratios of maximum suction-surface velocity to trailing-edge velocity correlated well in the midspan region, with the measured total-parameters over the minimum-loss to near stall operating range for all stators and speeds studied. The potential benefits of a blade designed with the aid of these flow analysis codes are illustrated by a proposed redesign of one of the four stators studied. An overall efficiency improvement of 1.6 points above the peak measured for that stator is predicted for the redesign.

Gelder, T. F.; Schmidt, J. F.; Esgar, G. M.

1980-01-01

270

The effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model, volume 1  

NASA Technical Reports Server (NTRS)

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence on airfoil heat transfer. Heat transfer measurements were obtained using low conductivity airfoils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient (incidence), first-stator/rotor axial spacing, Reynolds number, and relative circumferential position of the first and second stators. Aerodynamic measurements include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Analytical results include airfoil heat transfer predictions and a examination of solutions of the unstead boundary layer equipment.

Dring, R. P.; Blair, M. F.; Joslyn, H. D.; Power, G. D.; Verdon, J. M.

1987-01-01

271

The torque ripple reduction of a concentrated winding synchronous reluctance motor according to stator and rotor structure variations using response surface methodology  

NASA Astrophysics Data System (ADS)

This paper deals with optimum design criteria to minimize the torque ripple of a concentrated winding synchronous reluctance motor (SynRM) using response surface methodology (RSM). The feasibility of using RSM with the finite element method in practical engineering problem is investigated with computational examples and comparison between the fitted response and the results obtained from an analytical solution according to the design variables of stator and rotor in concentrated winding SynRM (6slot).

Choi, Yun-Chul; Lee, Jung-Ho; Hong, Jung Pyo

2008-04-01

272

Influence of stator winding structure on the relation between PD value and maximum discharge quantity in deterioration diagnosis of hydro-generators  

Microsoft Academic Search

In this study, the authors investigated on-line deterioration diagnosis of hydro-generators. Simultaneous measurement was done under off-line condition by using an on-line PD monitor and an off-line PD measuring system. When a stator had wave-winding structure, a good correlation between the maximum electric discharges of the offline PD measuring system and PD values of the online PD monitor was seen.

Osamu Hattori; Takahiko Yamashita

2010-01-01

273

Eddy-Current Loss and Temperature Rise in the Form-Wound Stator Winding of an Inverter-Fed Cage Induction Motor  

Microsoft Academic Search

Temperature rise of the form-wound multi-conductor stator winding of a 1250-kW cage induction motor was analyzed. Eddy currents in the winding significantly affect the temperature rise. The eddy current was modeled using time-discretized finite-element analysis (FEA). The resistive losses in each of the bars obtained from the FEA are used as input for thermal modeling. The distance from the air

M. J. Islam; H. V. Khang; A.-K. Repo; A. Arkkio

2010-01-01

274

Cold-air performance of free power turbine designed for 112-kilowatt automotive gas-turbine engine 3: Effect of stator vane end clearances on performance  

NASA Technical Reports Server (NTRS)

An experimental investigation of a free power turbine designed for a 112-kW, automotive, gas turbine engine was made to determine the penalty in performance due to the stator vane end clearances. Tests were made over a range of mean section stator vane angles from 26 deg to 50 deg (as measured from the plane of rotation) with the vane end clearances filled. These results were compared with test results of the same turbine with vane end clearances open. At design equivalent values of rotative speed and pressure ratio and at a vane angle of 35 deg, the mass flow with the vane and clearances filled was about 8 percent lower than mass flow with vane end clearances open. The decrease in mass flow was mitigated by increasing the vane angle. With the vane end clearances filled, there was about a 66 percent reduction in mass flow when the vane angle was decreased from 40 deg to 26 deg. For the same decrease in vane angle the stator throat area decreased by about 50 percent. This result indicates that the rotor losses were increasing with decreasing vane angle.

Kofskey, M. G.; Mclallin, K. L.

1978-01-01

275

Torque Generation in F1-ATPase Devoid of the Entire Amino-Terminal Helix of the Rotor That Fills Half of the Stator Orifice  

PubMed Central

F1-ATPase is an ATP-driven rotary molecular motor in which the central ?-subunit rotates inside a cylinder made of ?3?3 subunits. The amino and carboxyl termini of the ? rotor form a coiled coil of ?-helices that penetrates the stator cylinder to serve as an axle. Crystal structures indicate that the axle is supported by the stator at two positions, at the orifice and by the hydrophobic sleeve surrounding the axle tip. The sleeve contacts are almost exclusively to the longer carboxyl-terminal helix, whereas nearly half the orifice contacts are to the amino-terminal helix. Here, we truncated the amino-terminal helix stepwise up to 50 residues, removing one half of the axle all the way up and far beyond the orifice. The half-sliced axle still rotated with an unloaded speed a quarter of the wild-type speed, with torque nearly half the wild-type torque. The truncations were made in a construct where the rotor tip was connected to a ?-subunit via a short peptide linker. Linking alone did not change the rotational characteristics significantly. These and previous results show that nearly half the normal torque is generated if rotor-stator interactions either at the orifice or at the sleeve are preserved, suggesting that the make of the motor is quite robust.

Kohori, Ayako; Chiwata, Ryohei; Hossain, Mohammad Delawar; Furuike, Shou; Shiroguchi, Katsuyuki; Adachi, Kengo; Yoshida, Masasuke; Kinosita, Kazuhiko

2011-01-01

276

Exploring the possibilities to control the molecular switching properties and dynamics: A field-switchable rotor-stator molecular system  

NASA Astrophysics Data System (ADS)

A bistable, dipolar stator-rotor molecular system-candidate for molecular electronics is investigated. We demonstrate that it is possible to control the intramolecular torsional states and dynamics in this system by applying an appropriate additional electric field (instead of biasing one), achieving fine tuning and modulation of the relevant properties. The electric field effects on the quantities responsible for torsional dynamics (potential energy surface, potential barrier height, quantum and classical transition probabilities, correlation time, HOMO-LUMO gap) are studied from first principles. Our results indicate that it is possible to artificially stabilize the metastable conformational state of the studied molecule. The importance of this is evident, as the current-voltage characteristics of the metastable state are clearly distinguishable from the current-voltage characteristics of the two stable states. We report for the first time exact calculations related to the possibilities to control the thermally induced stochastic switching, and reduce the noise in a practical application. Thus, we believe that the molecule studied in this paper could operate as a field-switchable molecular device under real conditions.

Petreska, Irina; Pejov, Ljup?o; Kocarev, Ljup?o

2011-01-01

277

The Torque of Rotary F-ATPase Can Unfold Subunit Gamma If Rotor and Stator Are Cross-Linked  

PubMed Central

During ATP hydrolysis by F1-ATPase subunit ? rotates in a hydrophobic bearing, formed by the N-terminal ends of the stator subunits (??)3. If the penultimate residue at the ?-helical C-terminal end of subunit ? is artificially cross-linked (via an engineered disulfide bridge) with the bearing, the rotary function of F1 persists. This observation has been tentatively interpreted by the unfolding of the ?-helix and swiveling rotation in some dihedral angles between lower residues. Here, we screened the domain between rotor and bearing where an artificial disulfide bridge did not impair the rotary ATPase activity. We newly engineered three mutants with double cysteines farther away from the C-terminus of subunit ?, while the results of three further mutants were published before. We found ATPase and rotary activity for mutants with cross-links in the single ?-helical, C-terminal portion of subunit ? (from ?285 to ?276 in E. coli), and virtually no activity when the cross-link was placed farther down, where the C-terminal ?-helix meets its N-terminal counterpart to form a supposedly stable coiled coil. In conclusion, only the C-terminal singular ?-helix is prone to unwinding and can form a swivel joint, whereas the coiled coil portion seems to resist the enzyme's torque.

Hilbers, Florian; Junge, Wolfgang; Sielaff, Hendrik

2013-01-01

278

Prédiction des vibrations du stator d'une machine à réluctance variable en fonction du courant absorbé  

NASA Astrophysics Data System (ADS)

In order to predict the radial vibration of the stator core of a Doubly Salient Switched Reluctance Motor (D.S.S.R.M.), different causes of vibrations are considered. In this kind of machine, electromagnetic stress is found to be the most significant cause of vibrations. The local magnetic stress distribution, depending on magnetic field and finally on the phase current, is calculated in the case of an unsatured operation. This magnetic stress acts in two ways: a tangential force (torque) and a radial attractive force. This radial force excites the vibration modes of the stator, this vibration behaviour is measured in the aligned position and is identified as a transfert function. Finally several experiments show the good accuracy of this simple model. This model will be later used to study the effect of phase current and of static converter on vibration and acoustic noise emitted by the D.S.S.R.M. L'étude du bruit et des vibrations dans le matériel électrique fait intervenir plusieurs systèmes physiques couplés. Le modèle complet est complexe et ne permet pas d'études paramétriques simples de la structure de la machine, de son alimentation et cela pour différents points de fonctionnement. Dans cet article est présenté un modèle simple permettant de prédire l'accélération radiale d'un Moteur à Réluctance Variable à Double Saillance (M.R.V.D.S.) en fonction du courant d'alimentation. Ce modèle permettra d'étudier ultérieurement l'influence de l'alimentation sur le comportement vibratoire de la machine. En premier lieu, les différentes sources de vibrations d'une machine tournante sont évoquées, pour finalement ne s'intéresser qu'aux efforts d'origine magnétique qui sont prépondérants dans les M.R.V.D.S. Le calcul de ces efforts en fonction du courant est présenté dans le cas d'une machine fonctionnant en régime linéaire (sans saturation magnétique). Ces efforts sont décomposés en une force tangentielle créant le couple de rotation et une force radiale ne créant aucun couple. Les formulations sont appliquées à une M.R.V.D.S. de type 6/4 d'une puissance de 30 W. Une identification expérimentale du comportement vibratoire de la machine à rotor bloqué et en monophasé permet de connaître la réponse de la structure à ces efforts magnétiques. Cette réponse mécanique est identifiée à une fonction de transfert. Le modèle complet prend en compte l'alimentation de la machine, la relation entre le courant d'ajimentation et les efforts ainsi que la réponse vibratoire de la machine à ces efforts. Enfin des résultats expérimentaux originaux permettent de valider le modèle dans le cadre des hypothèses définies.

Camus, F.; Gabsi, M.; Multon, B.

1997-02-01

279

Statistic-based spectral indicator for bearing fault detection in permanent-magnet synchronous machines using the stator current  

NASA Astrophysics Data System (ADS)

In this paper, an original method for bearing fault detection in high speed synchronous machines is presented. This method is based on the statistical process of Welch's periodogram of the stator currents in order to obtain stable and normalized fault indicators. The principle of the method is to statistically compare the current spectrum to a healthy reference so as to quantify the changes over the time. A statistic-based indicator is then constructed by monitoring specific harmonic family. The proposed method was tested on two experimental test campaigns for four different speeds and compared to a vibration indicator. The method was evaluated using a rigorous performance evaluation metric. A threshold evaluation was performed and shows that the proposed method is very tolerant to the machine speed. Thus, the use of a unique fault threshold whatever the speed can be considered. Results showed excellent agreement as compared with the vibration indicator, with an overall correlation of r=0.74 and only 4% of false alarms. Performance demonstrated by this novel method was superior to those of a classical energy-based indicator in terms of correlation with the vibration indicator and detection stability. Moreover, results also showed a better robustness of the proposed method since good performance can be obtained with the same detection threshold whatever the speed or the measure campaign whereas it needs to be redefined for each case with the classical indicator. This work shows the advantages of a statistic-based approach in order to increase the robustness of bearing fault detection in permanent-magnet synchronous machines.

Picot, A.; Obeid, Z.; Régnier, J.; Poignant, S.; Darnis, O.; Maussion, P.

2014-06-01

280

Tribenzotriquinacene receptors for c60 ?fullerene rotors: towards c3 symmetrical chiral stators for unidirectionally operating nanoratchets.  

PubMed

The synthesis of a stereochemically pure concave tribenzotriquinacene receptor (7) for C60 fullerene, possessing C3 point group symmetry, by threefold condensation of C2 -symmetric 1,2-diketone synthons (5) and a hexaaminotribenzotriquinacene core (6) is described. The chiral diketone was synthesized in a five-step reaction sequence starting from C2h -symmetric 2,6-di-tert-butylanthracene. The highly diastereo-discriminating Diels-Alder reaction of 2,6-di-tert-butylanthracene with fumaric acid di(-)menthyl ester, catalyzed by aluminium chloride, is the relevant stereochemistry introducing step. The structure of the fullerene receptor was verified by (1) H and (13) C?NMR spectroscopy, mass spectrometry and single crystal X-ray diffraction. VCD and ECD spectra were recorded, which were corroborated by ab initio DFT calculations, establishing the chiral nature of 7 with about 99.7?% ee, based on the ee (99.9?%) of the chiral synthon (1). The absolute configuration of 7 could thus be established as all-S [(2S,7S,16S,21S,30S,35S)-(7)]. Spectroscopic titration experiments reveal that the host forms 1:1 complexes with either pure fullerene (C60 ) or fullerene derivatives, such as rotor 1'-(4-nitrophenyl)-3'-(4-N,N-dimethylaminophenyl)-pyrazolino[4',5':1,2][60]fullerene (R). The complex stability constants of the complexes dissolved in CHCl3 /CS2 (1:1 vol.?%) are K([C60 ?7])=319(±156)?M(-1) and K([R?7])=110(±50)?M(-1) . With molecular dynamics simulations using a first-principles parameterized force field the asymmetry of the rotational potential for [R?7] was shown, demonstrating the potential suitability of receptor 7 to act as a stator in a unidirectionally operating nanoratchet. PMID:24965605

Bredenkötter, Björn; Grzywa, Maciej; Alaghemandi, Mohammad; Schmid, Rochus; Herrebout, Wouter; Bultinck, Patrick; Volkmer, Dirk

2014-07-14

281

Moteurs piézo-électriques à onde progressive : I. Modélisation de la conversion d'énergie mécanique à l'interface stator/rotor  

NASA Astrophysics Data System (ADS)

The modeling of traveling wave type piezoelectric motors involves a large variety of mechanical and physical phenomena and therefore leads to numerous approaches and models. The latter, mainly based on phenomenological and numerical (based on Finite Element Method) analyses, are not suitable for current objectives oriented toward the development of efficient C.A.D. tools. As a result, an attempt is done to investigate analytical approaches, in order to theoretically model the mechanical energy conversion at the stator/rotor interface. This paper is the first in a serie of three articles devoted to the modeling of such rotative motors. After a short description of the operating principles specific to the piezomotors, the mechanical and tribological assumptions made for the driving mechanism of the rotor are briefly described. Then it is shown that the kinematic and dynamic modeling of the stator, combined with the static representation of the stator/rotor interface, gives an efficient way in order to perform the calculation of the loading characteristics of the driving shaft. Finally, the specifications of a new software named C.A.S.I.M.M.I.R.E., which has been recently developed on the basis of our earlier mechanical modeling, are described. In the last of these three papers, the theoretical simulations performed on SHINSEI Japanese motors will show to be close to the experimental data and that the results reported in this paper will lead to the structural optimization of future traveling wave ultrasonic motors. La modélisation des moteurs piézo-électriques à onde progressive implique une grande variété de phénomènes physiques et mécaniques. Cette variété conduit à des approches et modèles tout aussi nombreux et variés, qui reposent principalement sur des analyses phénoménologiques et numériques (Méthode Élements Finis), et ne permettent pas de répondre aux éxigences actuelles concernant le développement d'outils C.A.O. performants. Cette nécessité nous a conduits à développer une modélisation théorique analytique de la conversion d'énergie à l'interface stator/rotor. Ce papier est le premier d'une série de trois articles consacrés à la modélisation des moteurs piézo-électriques rotatifs. Après une rapide description des principes de fonctionnement de ces piézomoteurs, les hypothèses mécaniques et tribologiques concernant le mécanisme d'entraînement du rotor sont énoncées succinctement. On démontre ensuite que la modélisation cinématique et dynamique du stator, combinée à une représentation statique du comportement à l'interface stator/rotor, autorise l'évaluation des caractéristiques en charge des moteurs à onde progressive. Enfin, le logiciel baptisé C.A.S.I.M.M.I.R.E., récemment développé sur la base de la modélisation mécanique précédente, est présenté puis testé. Dans le dernier article de cette série, nous confirmerons la validité des simulations théoriques issues de ce logiciel, à partir de la caractérisation expérimentale de moteurs japonais de la firme SHINSEI. Ce nouveau logiciel constitue d'ores et déjà un outil performant en vue de l'optimisation des futurs moteurs à onde progressive, et a déjà fait l'objet d'une première exploitation en milieu industriel.

Minotti, P.; Le Moal, P.; Buchaillot, L.; Ferreira, A.

1996-10-01

282

Commande vectorielle de la machine a reluctance variable à stator lisse. Prise en compte de la saturation et de l'amortissement  

NASA Astrophysics Data System (ADS)

This paper deals with the field-oriented control of a smooth stator, non excited salient rotor synchronous machine. First, a nonlinear modelling of the machine, taking into account both damping and saturation effects, is developed in PARK's rotor-bound frame. Then, a vector control strategy, which maintains a constant saturation level in the machine, is set-up. This strategy, wich consists in keeping the stator direct current at a high constant value, allows to linearize the model of the machine and to control it in the same way as a DC machine. A numerical simulation of a VRM, fed by a PWM-VSI and controlled thanks to this control strategy, is built up and the computed results are given and commented. Cet article est consacré à la commande vectorielle d'une machine à réluctance variable à stator lisse et rotor massif. D'abord, une modélisation non linéaire de la machine a été effectuée dans le repère de Park. Cette dernière permet de prendre en compte l'effet d'amortissement dû au rotor massif, ainsi que celui de la saturation inhérent à ce genre de machine. Ensuite, une stratégie de contrôle vectoriel, qui maintient un niveau de saturation constant dans la machine, a été élaborée. Cette stratégie, qui consiste à maintenir le courant direct statorique à une valeur élevée, permet de linéariser le modèle de la machine et ainsi de pouvoir la contrôler comme une machine à courant continu. Une simulation numérique de la machine à réluctance variable, alimentée par un onduleur de tension à MLI et commandée par la stratégie mise au point, a été effectuée. Les résultats de cette simulation sont donnés et commentés à la fin de l'article.

Tounzi, A.; Meibody-Tabar, F.; Sargos, F. M.

1997-04-01

283

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 2: Data and performance for stage A  

NASA Technical Reports Server (NTRS)

Stage A, comprised of a conventional rotor and stator, was designed and tested to establish a performance baseline for comparison with the results of subsequent tests planned for two tandem-blade stages. The rotor had an inlet hub/tip ratio of 0.8 and a design tip velocity of 757 ft/sec. At design equivalent rotor speed, rotor A achieved a maximum adiabatic efficiency of 85.1 percent at a pressure ratio of 1.29. The stage maximum adiabatic efficiency was 78.6 percent at a pressure ratio of 1.27.

Brent, J. A.

1972-01-01

284

Single-stage experimental evaluation of tandem-airfoil rotor and stator blading for compressors. Part 5: Analysis and design of stages D and E  

NASA Technical Reports Server (NTRS)

A conventional and a tandem bladed stage were designed for a comparative experimental evaluation in a 0.8 hub/tip ratio single-stage compressor. Based on a preliminary design study, a radially constant work input distribution was selected for the rotor designs. Velocity diagrams and blade leading and trailing edge angles selected for the conventional rotor and stator were used in the design of the tandem blading. The effects of axial velocity ratio and secondary flow on turning were included in the selection of blade leading and trailing edge angles. Design values of rotor tip velocity and stage pressure ratio were 757 ft/sec and 1.26, respectively.

Brent, J. A.; Cheatham, J. G.; Clemmons, D. R.

1972-01-01

285

Single-stage evaluation of highly-loaded high-Mach-number compressor stages 5. Data and performance of baseline, corner-blow wall suction and combined corner blow wall suction stator  

NASA Technical Reports Server (NTRS)

A single-stage compressor with a rotor tip speed of 1600 ft/sec and a 0.5 hub tip ratio was used to investigate the effects of several stator endwall treatment methods on stage range and performance. These endwall treatment methods consisted of stator corner-blow, annular wall suction upstream of stator leading edge, and combined corner-blow and annular wall suction. The overall stage performance with corner blow was essentially the same as the baseline performance. The performance for the annular wall suction and the combined corner-blow and wall suction showed a reduction in peak efficiency of 2.5 percentage points compared to the baseline data.

Nikkanen, J. P.; Brooky, J. P.

1972-01-01

286

Análisis descriptivo del tamaño relativo del gasto del gobierno chileno  

Microsoft Academic Search

En este trabajo se examina el tamaño relativo del Gobierno chileno a través de una comparación internacional con valores equivalentes de otros países. Adicionalmente hay un análisis similar para dos componentes importantes del gasto público: educación y salud. El gasto del Gobierno de Chile, valor en torno del 20% (PIB), está junto al tercio inferior de países que poseen un

Eduardo Engel; Patricio Meller; Claudio Bravo

1998-01-01

287

Variable stator radial turbine  

NASA Technical Reports Server (NTRS)

A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

Rogo, C.; Hajek, T.; Chen, A. G.

1984-01-01

288

Cold air study of the effect on turbine stator blade aerodynamic performance of coolant ejection from various trailing edge slot geometries. 2: Comparison of experimental and analytical results  

NASA Technical Reports Server (NTRS)

Experimentally determined efficiencies of turbine stator blades having trailing-edge coolant ejection are compared with efficiencies predicted from two previously published approximate analytical methods. The experimental results were obtained from two-dimensional data with the temperature of the primary and coolant flows both being nearly ambient. Data from five stator blade configurations having different slotted trailing-edge geometries were included in the comparison. The two analytical methods gave results which agreed reasonably well with experimental results. An average of the absolute values of differences between experimental and predicted efficiencies for all five blade configurations showed that one method gave average efficiency differences which were about 1.3 percent different than experimental efficiencies, while the other method gave average efficiency differences that were about 0.7 percent different than experimental. However, in some instances, maximum differences of as much as 4 percent occurred. A comparison between experimental and analytical results indicated that the ratio of trailing-edge slot width to trailing-edge thickness influences the measured efficiencies to a greater extent than is accounted for by either analytical model.

Prust, H. W., Jr.

1975-01-01

289

Mode-splitting and quasi-degeneracies in circular plate vibration problems: The example of free vibrations of the stator of a traveling wave ultrasonic motor  

NASA Astrophysics Data System (ADS)

In systems with rotational symmetry, bending modes occur in doubly-degenerate pairs with two independent vibration modes for each repeated natural frequency. In circular plates, the standing waves of two such degenerate bending modes can be superposed with a 1/4 period separation in time to yield a traveling wave response. This is the principle of a traveling wave ultrasonic motor (TWUM), in which a traveling bending wave in a stator drives the rotor through a friction contact. The stator contains teeth to increase the speed at the contact region, and these affect the rotational symmetry of the plate. When systems with rotational symmetry are modified either in their geometry, or by spatially varying their properties or boundary conditions, some mode-pairs split into singlet modes having distinct frequencies. In addition, coupling between some pairs of distinct unperturbed modes also causes quasi-degeneracies in the perturbed modes, which leads their frequency curves to approach and veer away in some regions of the parameter space. This paper discusses the effects of tooth geometry on the behavior of plate modes under free vibration. It investigates mode splitting and quasi-degeneracies and derives analytic expressions to predict these phenomena, using variational methods and a degenerate perturbation scheme for the solution to the plate's discrete eigenvalue problem; these expressions are confirmed by solving the discrete eigenvalue problem of the plate with teeth.

Kumar, Ashwin; Krousgrill, Charles M.

2012-12-01

290

Contribution of many charged residues at the stator-rotor interface of the Na+-driven flagellar motor to torque generation in Vibrio alginolyticus.  

PubMed

In torque generation by the bacterial flagellar motor, it has been suggested that electrostatic interactions between charged residues of MotA and FliG at the rotor-stator interface are important. However, the actual role(s) of those charged residues has not yet been clarified. In this study, we systematically made mutants of Vibrio alginolyticus whose charged residues of PomA (MotA homologue) and FliG were replaced by uncharged or charge-reversed residues and characterized the motilities of those mutants. We found that the members of a group of charged residues, 7 in PomA and 6 in FliG, collectively participate in torque generation of the Na(+)-driven flagellar motor in Vibrio. An additional specific interaction between PomA-E97 and FliG-K284 is critical for proper performance of the Vibrio motor. Our results also reveal that more charged residues are involved in the PomA-FliG interactions in the Vibrio Na(+)-driven motor than in the MotA-FliG interactions in the H(+)-driven one. This suggests that a larger number of conserved charged residues at the PomA-FliG interface contributes to the robustness of the Vibrio motor against mutations. The interaction surfaces of the stator and rotor of the Na(+)-driven motor seem to be more complex than those previously proposed in the H(+)-driven motor. PMID:24464458

Takekawa, Norihiro; Kojima, Seiji; Homma, Michio

2014-04-01

291

Effects of inlet turbulence and rotor/stator interactions on the aerodynamics and heat transfer of a large-scale rotating turbine model. Part 4: Aerodynamic data tabulation  

SciTech Connect

A combined experimental and analytical program was conducted to examine the effects of inlet turbulence and airfoil heat transfer. The experimental portion of the study was conducted in a large-scale (approx. 5X engine), ambient temperature, rotating turbine model configured in both single-stage and stage-and-a-half arrangements. Heat transfer measurements were obtained using low-conductivity air foils with miniature thermocouples welded to a thin, electrically heated surface skin. Heat transfer data were acquired for various combinations of low or high inlet turbulence intensity, flow coefficient, first stator-rotor axial spacing, Reynolds number and relative circumferential position of the first and second stators. Aerodynamic measurements obtained include distributions of the mean and fluctuating velocities at the turbine inlet and, for each airfoil row, midspan airfoil surface pressures and circumferential distributions of the downstream steady state pressures and fluctuating velocities. Results include airfoil heat transfer predictions produced using existing 2-D boundary layer computation schemes and an examination of solutions of the unsteady boundary layer equations.

Dring, R.P.; Joslyn, H.D.; Blair, M.F.

1987-11-01

292

A cylindrical micro-ultrasonic motor (stator transducer size: 1.4 mm in diameter and 5.0 mm long)  

PubMed

Ultrasonic motors are suitable for a micro-actuator because of a direct drive, no brake and their simple construction. In order to fabricate micro-ultrasonic motors, a piezoelectric thin film is essential. In this study, a hydrothermal method was adopted to deposit a PZT thin film. The dimensions of the stator transducer were: outer diameter, 1.4 mm; inner diameter, 1.2 mm; and length, 5.0 mm. The resonance frequency of the stator transducer was 227 kHz, and the vibration amplitude was 58 nmp-p at an input voltage of 4.0 Vp-p. The maximum revolution speed was 680 rpm, and the maximum starting torque was 0.67 microNm. The experimental conditions were 20 Vp-p and 5.3 mN pre-load. The motor property versus scale was investigated using an equivalent circuit. The calculated results indicated that the output torque of the 100 microns diameter motor was 27 nNm. PMID:10829623

Morita; Kurosawa; Higuchi

2000-03-01

293

New solutions in the maintenance of the asynchronous motors with integrated gear and single demountable bearing shield: Devices to extract and insert the ferromagnetic cores of the stator (case study)  

Microsoft Academic Search

Generally, asynchronous motors used in actuator systems (whether they are three-phase or single-phase motors) have two demountable bearing shields. This design allows easy access to the winding, on both sides of the stator, making the maintenance a relatively simple process. Another type of motor, with a special design, also exists. It has a single removable bearing shield, the other being

Daniel Necula; Nicolae Vasile; Mihail-Florin Stan

2011-01-01

294

Atlas del Genoma del Cáncer  

Cancer.gov

Es posible que haya más de 200 tipos diferentes de cáncer y muchos subtipos más, cada uno de estos causado por errores en el ADN que desencadenan el crecimiento descontrolado de las células. La identificación de los cambios en el conjunto completo de ADN de cada tipo de cáncer, su genoma, y el entendimiento de cómo interactúan dichos cambios para impulsar el proceso de la enfermedad sentarán las bases de una era individualizada de tratamiento del cáncer.

295

Como Lo Hago Yo: Tratamiento Quirurgico Del Mielomeningocele  

PubMed Central

En Argentina hay plan de fortificación con ácido fólico. Diagnostico prenatal no siempre es correcto. Cierre según técnica. Cerramos músculo. No favorecemos corpectomía temprana en casos de cifosis. Suturamos la plaqueta. Cerramos el plano muscular. Hidrocefalia: Válvula de derivación, generalmente dentro de los dos primeros meses. Ventriculostomía no está indicada. Chiari II. Laminectomia cervical alta. Siringomielia: Derivación desde la cavidad al peritoneo.

Portillo, Santiago

2014-01-01

296

Two dimensional cold air cascade study of a film cooled turbine stator blade. 2: Experimental results of full film cooling tests  

NASA Technical Reports Server (NTRS)

The effect of full film cooling on the performance of a turbine stator blade was studied in a two-dimensional cascade. The blade contained 12 rows of coolant holes, 6 rows on the suction surface and 6 on the pressure surface. Separate tests were first made with coolant ejection from each of the 12 rows. Then successive tests were made with various combinations of coolant rows open, including full film cooling. The principal results are presented in terms of primary-air efficiency as a function of coolant fraction. In addition, the efficiency results of the multirow tests are compared with the multi-row efficiency predicted by adding the single-row results.

Prust, H. W., Jr.

1975-01-01

297

Blade row dynamic digital compression program. Volume 2: J85 circumferential distortion redistribution model, effect of Stator characteristics, and stage characteristics sensitivity study  

NASA Technical Reports Server (NTRS)

The results of dynamic digital blade row compressor model studies of a J85-13 engine are reported. The initial portion of the study was concerned with the calculation of the circumferential redistribution effects in the blade-free volumes forward and aft of the compression component. Although blade-free redistribution effects were estimated, no significant improvement over the parallel-compressor type solution in the prediction of total-pressure inlet distortion stability limit was obtained for the J85-13 engine. Further analysis was directed to identifying the rotor dynamic response to spatial circumferential distortions. Inclusion of the rotor dynamic response led to a considerable gain in the ability of the model to match the test data. The impact of variable stator loss on the prediction of the stability limit was evaluated. An assessment of measurement error on the derivation of the stage characteristics and predicted stability limit of the compressor was also performed.

Tesch, W. A.; Steenken, W. G.

1978-01-01

298

Cold-air study of the effect on turbine stator blade aerodynamic performance of coolant ejection from various trailing-edge slot geometries. 1: Experimental results  

NASA Technical Reports Server (NTRS)

Trailing-edge slot configurations were investigated in a two-dimensional cascade of turbine stator blades. The trailing-edge slots were incorporated into blades with round trailing edges. The five blade configurations investigated included blades with two different trailing-edge thicknesses and four different slot widths. The results of the investigation showed that there was, in general, a significant increase in primary-air efficiency due to the coolant flow, the increase varying with slot configuration. For the five configurations tested, the average percent change in primary-air efficiency per percent coolant flow varied almost linearly from zero to about 1.4 percent over a range of coolant- to primary-air exit-velocity ratios between 0 and 1.2. However, for different configurations there was considerable deviation from the average values in the lower range of exit velocity ratios.

Prust, H. W., Jr.; Bartlett, W. M.

1974-01-01

299

MotPS is the stator-force generator for motility of alkaliphilic Bacillus, and its homologue is a second functional Mot in Bacillus subtilis.  

PubMed

The stator-force generator that drives Na+-dependent motility in alkaliphilic Bacillus pseudofirmus OF4 is identified here as MotPS, MotAB-like proteins with genes that are downstream of the ccpA gene, which encodes a major regulator of carbon metabolism. B. pseudofirmus OF4 was only motile at pH values above 8. Disruption of motPS resulted in a non-motile phenotype, and motility was restored by transformation with a multicopy plasmid containing the motPS genes. Purified and reconstituted MotPS from B. pseudofirmus OF4 catalysed amiloride analogue-sensitive Na+ translocation. In contrast to B. pseudofirmus, Bacillus subtilis contains both MotAB and MotPS systems. The role of the motPS genes from B. subtilis in several motility-based behaviours was tested in isogenic strains with intact motAB and motPS loci, only one of the two mot systems or neither mot system. B. subtilis MotPS (BsMotPS) supported Na+-stimulated motility, chemotaxis on soft agar surfaces and biofilm formation, especially after selection of an up-motile variant. BsMotPS also supported motility in agar soft plugs immersed in liquid; motility was completely inhibited by an amiloride analogue. BsMotPS did not support surfactin-dependent swarming on higher concentration agar surfaces. These results indicate that BsMotPS contributes to biofilm formation and motility on soft agar, but not to swarming, in laboratory strains of B. subtilis in which MotAB is the dominant stator-force generator. BsMotPS could potentially be dominant for motility in B. subtilis variants that arise in particular niches. PMID:15306009

Ito, Masahiro; Hicks, David B; Henkin, Tina M; Guffanti, Arthur A; Powers, Benjamin D; Zvi, Lior; Uematsu, Katsuyuki; Krulwich, Terry A

2004-08-01

300

Windage Power Loss in Gas Foil Bearings and the Rotor-Stator Clearance of High Speed Generators Operating in High Pressure Environments  

NASA Technical Reports Server (NTRS)

Closed Brayton Cycle (CBC) and Closed Supercritical Cycle (CSC) engines are prime candidates to convert heat from a reactor into electric power for robotic space exploration and habitation. These engine concepts incorporate a permanent magnet starter/generator mounted on the engine shaft along with the requisite turbomachinery. Successful completion of the long-duration missions currently anticipated for these engines will require designs that adequately address all losses within the machine. The preliminary thermal management concept for these engine types is to use the cycle working fluid to provide the required cooling. In addition to providing cooling, the working fluid will also serve as the bearing lubricant. Additional requirements, due to the unique application of these microturbines, are zero contamination of the working fluid and entirely maintenance-free operation for many years. Losses in the gas foil bearings and within the rotor-stator gap of the generator become increasingly important as both rotational speed and mean operating pressure are increased. This paper presents the results of an experimental study, which obtained direct torque measurements on gas foil bearings and generator rotor-stator gaps. Test conditions for these measurements included rotational speeds up to 42,000 revolutions per minute, pressures up to 45 atmospheres, and test gases of nitrogen, helium, and carbon dioxide. These conditions provided a maximum test Taylor number of nearly one million. The results show an exponential rise in power loss as mean operating density is increased for both the gas foil bearing and generator windage. These typical "secondary" losses can become larger than the total system output power if conventional design paradigms are followed. A nondimensional analysis is presented to extend the experimental results into the CSC range for the generator windage.

Bruckner, Robert J.

2009-01-01

301

Instantánea del cáncer infantil  

Cancer.gov

Información sobre la incidencia y mortalidad del cáncer en los niños, tendencias en el financiamiento del NCI para la investigación del cáncer infantil; así como ejemplos de actividades y adelantos en la investigación relevantes para esta población.

302

Políticas del sitio web  

Cancer.gov

En el sitio web del NCI se proporcionan enlaces a otros sitios web con fines informativos y para conveniencia del público. Si el usuario selecciona un sitio web externo, saldrá del sitio web del NCI y estará sujeto a las políticas de privacidad y seguridad de dicho sitio.

303

Cold-air performance of a 15.41-cm-tip-diameter axial-flow power turbine with variable-area stator designed for a 75-kW automotive gas turbine engine  

NASA Technical Reports Server (NTRS)

An experimental evaluation of the aerodynamic performance of the axial flow, variable area stator power turbine stage for the Department of Energy upgraded automotive gas turbine engine was conducted in cold air. The interstage transition duct, the variable area stator, the rotor, and the exit diffuser were included in the evaluation of the turbine stage. The measured total blading efficiency was 0.096 less than the design value of 0.85. Large radial gradients in flow conditions were found at the exit of the interstage duct that adversely affected power turbine performance. Although power turbine efficiency was less than design, the turbine operating line corresponding to the steady state road load power curve was within 0.02 of the maximum available stage efficiency at any given speed.

Mclallin, K. L.; Kofskey, M. G.; Wong, R. Y.

1982-01-01

304

Cold-air performance of free-power turbine designed for 112-kilowatt automotive gas-turbine engine. 1: Design Stator-vane-chord setting angle of 35 deg  

NASA Technical Reports Server (NTRS)

A cold air experimental investigation of a free power turbine designed for a 112-kW automotive gas-turbine was made over a range of speeds from 0 to 130 percent of design equivalent speeds and over a range of pressure ratio from 1.11 to 2.45. Results are presented in terms of equivalent power, torque, mass flow, and efficiency for the design power point setting of the variable stator.

Kofskey, M. G.; Nusbaum, W. J.

1978-01-01

305

Design and Characteristics of Mode-Coupling LiNbO3 Ultrasonic Motor Depended on Width-to-Length Ratio of the Stator Vibrator  

NASA Astrophysics Data System (ADS)

A miniature ultrasonic motor fabricated from a LiNbO3 rectangular plate was studied to improve its rotation characteristics. In this motor, the coupling modes of in-plane longitudinal and flexural modes caused by crystal anisotropy are used to realize a single-phase drive motor. The mode coupling vibrator is designed to have crystal cut angles and the width-to-length ratio W/L of the vibrator shape. In this study, we noted the new coupling condition of W/L? 0.84 compared with the conventional ratio of W/L=0.255. We considered the mechanism of the mode coupling and the design of the stator vibrator by finite element method analysis and experiments. From the results, we fabricated and investigated prototype motors of the vibrator with dimensions of 10× 2.55× 0.5 and 4.10× 3.48× 0.5 mm3. The newly designed motor with the vibrator of W/L=0.849 improved the motor characteristics for the equalization of rotation in both directions.

Hideki Tamura,; Takanori Morooka,; Yasuhiro Yamayoshi,; Manabu Aoyagi,; Takehiro Takano,; Seiji Hirose,

2010-07-01

306

Construction of functional fragments of the cytoplasmic loop with the C-terminal region of PomA, a stator component of the Vibrio Na+ driven flagellar motor.  

PubMed

The membrane motor proteins, PomA (polar flagellar motility protein A) and PomB (polar flagellar motility protein B), of Vibrio alginolyticus form a stator complex that converts energy from the ion flow to mechanical work in bacterial flagellar motors. The cytoplasmic domain of PomA is believed to interact with the rotor protein FliG to make a torque. In this study, to investigate the function of the cytoplasmic domain of PomA, we constructed a series of fragments that flank the cytoplasmic loop of PomA between the second and third transmembrane (TM) domains (A-loop) and the C-terminal region, and expressed them in Escherichia coli together with PomA and PotB (a chimeric protein of PomB and MotB). We observed a dominant-negative effect of one PomA fragment on motility. We confirmed that these PomA fragments localized both in the membrane fraction and in the cytoplasmic fraction, and induced bacterial growth delay. Effect of additional point and deletion mutations into this fragment implies that the C-terminal region and TM domains used as a linker play a significant part in these observations. From these results, we conclude that the PomA fragments retain the structure important for functions. We expect that further constructions will provide a variety of experimental approaches to characterize the interaction between PomA and FliG. PMID:24398784

Onoue, Yasuhiro; Abe-Yoshizumi, Rei; Gohara, Mizuki; Kobayashi, Shiori; Nishioka, Noriko; Kojima, Seiji; Homma, Michio

2014-03-01

307

Rotor power losses in planar radial magnetic bearings -- Effects of number of stator poles, air gas thickness, and magnetic flux density  

SciTech Connect

Rotor power losses in magnetic bearings cannot be accurately calculated at this time because of the complexity of the magnetic field distribution and several other effects. The losses are due to eddy currents, hysteresis, and windage. This paper presents measured results in radial magnetic bearing configurations with eight pole and 16 pole stators and two laminated rotors. Two different air gaps were tested. The rotor power losses were determined by measuring the rundown speed of the rotor after the rotor was spun up to speeds of approximately 30,000 rpm, DN + 2,670,000 mm-rpm, in atmospheric air. The kinetic energy of the rotor is converted to heat by magnetic and air drag power loss mechanisms during the run down. Given past publications and the opinions of researchers in the field, the results were quite unexpected. The measured power losses were found to be nearly independent of the number of poles in the bearing. Also, the overall measured rotor power loss increased significantly as the magnetic flux density increased and also increased significantly as the air gap thickness decreased. A method of separating the hysteresis, eddy current and windage losses is presented. Eddy current effect were found to be the most important loss mechanism in the data analysis, for large clearance bearings. Hysteresis and windage effects did not change much from one configuration to the other.

Allaire, P.E.; Kasarda, M.E.F.; Fujita, L.K.

1999-10-01

308

Instantánea del cáncer colorrectal  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer colorrectal; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

309

Crystallographic and Molecular Dynamics Analysis of Loop Motions Unmasking the Peptidoglycan-Binding Site in Stator Protein MotB of Flagellar Motor  

PubMed Central

Background The C-terminal domain of MotB (MotB-C) shows high sequence similarity to outer membrane protein A and related peptidoglycan (PG)-binding proteins. It is believed to anchor the power-generating MotA/MotB stator unit of the bacterial flagellar motor to the peptidoglycan layer of the cell wall. We previously reported the first crystal structure of this domain and made a puzzling observation that all conserved residues that are thought to be essential for PG recognition are buried and inaccessible in the crystal structure. In this study, we tested a hypothesis that peptidoglycan binding is preceded by, or accompanied by, some structural reorganization that exposes the key conserved residues. Methodology/Principal Findings We determined the structure of a new crystalline form (Form B) of Helicobacter pylori MotB-C. Comparisons with the existing Form A revealed conformational variations in the petal-like loops around the carbohydrate binding site near one end of the ?-sheet. These variations are thought to reflect natural flexibility at this site required for insertion into the peptidoglycan mesh. In order to understand the nature of this flexibility we have performed molecular dynamics simulations of the MotB-C dimer. The results are consistent with the crystallographic data and provide evidence that the three loops move in a concerted fashion, exposing conserved MotB residues that have previously been implicated in binding of the peptide moiety of peptidoglycan. Conclusion/Significance Our structural analysis provides a new insight into the mechanism by which MotB inserts into the peptidoglycan mesh, thus anchoring the power-generating complex to the cell wall.

Nahar, Musammat F.; Buckle, Ashley M.; Roujeinikova, Anna

2011-01-01

310

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame using Ultra-Bright Cr-Doped GdAlO3 Thermographic Phosphor  

NASA Technical Reports Server (NTRS)

Luminescence-based surface temperature measurements from an ultra-bright Cr-doped GdAlO3 perovskite (GAP:Cr) coating were successfully conducted on an air-film-cooled stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing at UTSI was to demonstrate that reliable thermal barrier coating (TBC) surface temperatures based on luminescence decay of a thermographic phosphor could be obtained from the surface of an actual engine component in an aggressive afterburner flame environment and to address the challenges of a highly radiant background and high velocity gases. A high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine was coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick GAP:Cr thermographic phosphor layer was deposited by EB-PVD. The ultra-bright broadband luminescence from the GAP:Cr thermographic phosphor is shown to offer the advantage of over an order-of-magnitude greater emission intensity compared to rare-earth-doped phosphors in the engine test environment. This higher emission intensity was shown to be very desirable for overcoming the necessarily restricted probe light collection solid angle and for achieving high signal-to-background levels. Luminescence-decay-based surface temperature measurements varied from 500 to over 1000C depending on engine operating conditions and level of air film cooling.

Eldridge, Jeffrey I.; Jenkins, Thomas P.; Allison, Stephen W.; Wolfe, Douglas E.; Howard, Robert P.

2013-01-01

311

Boletín del Instituto Nacional del Cáncer - 16 de enero 2013  

Cancer.gov

El Boletín del Instituto Nacional del Cáncer ha suspendido su publicación a partir del 16 de enero de 2013. El archivo del Boletín, que cuenta con todas las ediciones publicadas desde 2009 a 2013, permanecerá a disposición de los lectores en el sitio web del NCI.

312

La teoria del pendolo  

Microsoft Academic Search

Il silenzio era tale che, ascoltando attentamente, si sarebbe potuto udire la voce dell'anima. Era proprio questo il motivo per cui Galileo si alzava ogni mattina di buon ora per dire le sue orazioni innanzi al maestoso altare del duomo. Guardava a lungo le volte intorno a lui cercando con lo sguardo la perfezione del creato e poi, con l'ambiguità

Di Claudio Chillemi

313

Evaluación del desempeño integral del sector transporte  

Microsoft Academic Search

Las organizaciones hoy por hoy buscan aplicar un sistema de indicadores que evalúe la gestión y el desempeño del sector transporte en materia económica, social, ambiental e integral, con el fin de garantizar a las partes interesadas una información confiable sobre los resultados de desempeño frente al desarrollo sostenible, que facilite el ingreso a mercados nacionales e internacionales a partir

Clara Inés Pardo Martínez

2007-01-01

314

Boletín del Instituto Nacional del Cáncer - 07-20-2010  

Cancer.gov

El doctor Harold Varmus, acompañado de su esposa Constance Casey (centro), presta juramento como director del NCI ante la Secretaria del Departamento de Salud y Servicios Humanos, Kathleen Sebelius, el lunes 12 de julio. (Foto cortesía de Chris Smith) El 12 de julio, el doctor Harold Varmus prestó juramento ante la Secretaria del Departamento de Salud y Servicios Humanos de los Estados Unidos, Kathleen Sebelios, como el decimocuarto director del Instituto Nacional del Cáncer.

315

Hojas informativas del NCI  

Cancer.gov

La colección de hojas informativas del NCI trata de una variedad de temas relacionados con el cáncer. Las hojas informativas se revisan y ponen al día de acuerdo a las investigaciones más recientes sobre el cáncer.

316

Il problema del litio.  

NASA Astrophysics Data System (ADS)

Contents: 1. Introduzione. 2. La nucleosintesi del Big Bang. 3. Il litio nelle stelle di popolazione II. 4. I modelli stellari standard. 5. Il litio negli ammassi aperti. 6. Meccanismi di distruzione "non standard". 7. I modelli non-standard applicati alla popolazione II. 8. L'evoluzione Galattica del litio. 9. Quali stelle producono litio? 10. Il litio come elemento chiave per dare un nome agli oggetti stellari più minuscoli. 11. Conclusioni.

D'Antona, F.

1995-03-01

317

Amenazas comerciales del Acuerdo Can-Mercosur para los sectores productivos del Valle del Cauca  

Microsoft Academic Search

El Acuerdo de Complementación Económica, suscrito entre la Comunidad Andina (CAN) y el Mercado Común del Sur (MERCOSUR), marca un avance hacia una integración económica y política más profunda en América Latina. Por tal razón, el objetivo del presente artículo es identificar los sectores del Valle del Cauca que revelan desventajas competitivas relativas, por lo que se pueden ver potencialmente

Lya Paola Sierra Suárez; José Tomás Peláez Soto

2008-01-01

318

EL DESARROLLO DEL PENSAMIENTO CRÍTICO DEL ESTUDIANTE. UNA FINALIDAD EDUCATIVA PENDIENTE DEL ÁREA CURRICULAR ESTUDIOS SOCIALES  

Microsoft Academic Search

Esta investigación tuvo como objetivo determinar las características del proceso instruccional en la tercera etapa del nivel de Educación Básica que contribuyen al desarrollo del pensamiento crítico del estudiante para satisfacer el imperativo legal vigente desde julio de 1980, particularmente para el área curricular Estudios Sociales. Durante cuatro años escolares en dos instituciones educativas que ofrecen el precitado nivel se

Haydée Páez

319

Espectroscopia del Cometa Halley  

NASA Astrophysics Data System (ADS)

Se reportan observaciones espectroscópicas del cometa Halley. Los espectros fueron tomados usando el espectrógrafo del telescopio reflector de 1 metro del Observatorio Nacional de Venezuela. Se utilizó óptica azul, con una red de difracción de 600 lineas/min, obteniéndose una dispersión de 74.2 A/mm y una resolución de 2.5 A, en el rango espectral de 3500 a 6500 A. Seis placas fueron tomadas con emulsión IIa-O y dos con IIa-D. Los tiempos de exposición fueron entre 10 y 150 minutos. El cometa se encontraba entre 0.70 y 1.04 UA del Sol, y entre 1.28 y 0.73 UA de la Tierra. Las emisiones más prominentes en el espectro, son las del CN, C2, y C3. Otras emisiones detectadas corresponden a CH, NH2 y Na. Los espectros muestran un fuerte continuo, indicando un contenido significativo de polvo. Se detectó mayor intensidad del contínuo, en la dirección anti solar, lo cual es evidencia de la cola de polvo.

Naranjo, O.; Fuenmayor, F.; Ferrin, L.; Bulka, P.; Mendoza, C.

1987-05-01

320

Multi-cycle recovery of lactoferrin and lactoperoxidase from crude whey using fimbriated high-capacity magnetic cation exchangers and a novel "rotor-stator" high-gradient magnetic separator.  

PubMed

Cerium (IV) initiated "graft-from" polymerization reactions were employed to convert M-PVA magnetic particles into polyacrylic acid-fimbriated magnetic cation exchange supports displaying ultra-high binding capacity for basic target proteins. The modifications, which were performed at 25?mg and 2.5?g scales, delivered maximum binding capacities (Qmax ) for hen egg white lysozyme in excess of 320?mg?g(-1) , combined with sub-micromolar dissociation constants (0.45-0.69?µm) and "tightness of binding" values greater than 49?L?g(-1) . Two batches of polyacrylic acid-fimbriated magnetic cation exchangers were combined to form a 5?g pooled batch exhibiting Qmax values for lysozyme, lactoferrin, and lactoperoxidase of 404, 585, and 685?mg?g(-1) , respectively. These magnetic cation exchangers were subsequently employed together with a newly designed "rotor-stator" type HGMF rig, in five sequential cycles of recovery of lactoferrin and lactoperoxidase from 2?L batches of a crude sweet bovine whey feedstock. Lactoferrin purification performance was observed to remain relatively constant from one HGMF cycle to the next over the five operating cycles, with yields between 40% and 49% combined with purification and concentration factors of 37- to 46-fold and 1.3- to 1.6-fold, respectively. The far superior multi-cycle HGMF performance seen here compared to that observed in our earlier studies can be directly attributed to the combined use of improved high capacity adsorbents and superior particle resuspension afforded by the new "rotor-stator" HGMS design. PMID:23335282

Brown, Geoffrey N; Müller, Christine; Theodosiou, Eirini; Franzreb, Matthias; Thomas, Owen R T

2013-06-01

321

Boletín del Instituto Nacional del Cáncer  

Cancer.gov

No se puede negar que vivimos en una comunidad global, en la que los eventos de una ciudad o país pueden tener graves consecuencias para los residentes de otra ciudad o país a miles de kilómetros de distancia. Ya sea la pandemia del virus H1N1, los recientes disturbios en Irán o la recesión económica mundial, es evidente que esta interconectividad trae consigo retos importantes. Pero también puede crear oportunidades sin precedentes, en particular aquellas que podrían mejorar sustancialmente la salud pública.

322

Pruebas de Papanicolaou y del virus del papiloma humano (VPH)  

Cancer.gov

Hoja informativa que describe los exámenes selectivos de detección del cáncer de cérvix, los cuales incluyen la prueba de Papanicolaou y la prueba de los virus del papiloma humano. La hoja informativa incluye también información acerca de las pautas de exámenes de detección del cáncer de cérvix.

323

Instantánea del cáncer de esófago  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de esófago; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

324

Instantánea del cáncer de próstata  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de próstata; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

325

Instantánea del cáncer de estómago  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de estómago; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

326

Instantánea del sarcoma de Kaposi  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el sarcoma de Kaposi; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

327

Instantánea del cáncer de tiroides  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de tiroides; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

328

Instantánea del cáncer de ovario  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de ovario; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

329

Instantánea del cáncer de endometrio  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de endometrio; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

330

Instantánea del cáncer de vejiga  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de vejiga; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

331

Instantánea del cáncer de riñón  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de riñón; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

332

Instantánea del cáncer de páncreas  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de páncreas; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

333

Instantánea del cáncer de pulmón  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de pulmón; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

334

Documenting Endangered Languages (DEL)  

NSF Publications Database

Full Proposal Preparation Instructions: This solicitation contains information that supplements the standard Grant Proposal Guide (GPG) proposal preparation guidelines. All DEL proposals for project grants and fellowships will receive specialist (ad hoc) and panel review within the NSF review process. More comprehensive information on NSF Award Conditions is contained in the NSF Grant Policy Manual (GPM) Chapter II, available electronically on the NSF Website at http://www.nsf.gov/...

335

Nevado del Huila, Columbia  

NASA Technical Reports Server (NTRS)

Nevado del Huila Volcano in Colombia is actually a volcanic chain running north to south, capped by a glacier. With peaks ranging in height from 2,600 to 5,780 meters (8,530 to 18,960 feet), Nevado del Huila is a stratovolcano composed of alternating layers of hardened lava, solidified ash, and volcanic rocks. Its first recorded eruption occurred in the mid-sixteenth century. The long-dormant volcano erupted again in mid-April 2007. A few months before the eruption, the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) on NASA's Terra satellite captured this image of Nevado del Huila, on February 23, 2007. In this image, the bright white area just east of the central summit is ice. Immediately west of the summit are bare rocks, appearing as blue-gray. West of those rocks, white reappears, but this patch of white results from clouds hovering in the nearby valley. In the east, the colors turn to brown (indicating bare rock) and bright green (indicating vegetation). ASTER photographed Nevado del Huila near the end of a long phase of quietude. On April 17, 2007, local authorities recorded seismic activity associated with rock fracturing on the volcano's central summit, according to the ReliefWeb Website. Activity intensified the following day with an eruption and mudflows, forcing thousands of nearby residents to evacuate. As the Associated Press reported, the eruption caused avalanches and floods that wiped away both houses and bridges. It marked the volcano's first recorded eruption since the Spanish colonized the area five centuries earlier. NASA image created by Jesse Allen, using data provided courtesy of the NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.

2007-01-01

336

Boletín del Instituto Nacional del Cáncer - 02-02-2010  

Cancer.gov

En un estudio clínico en fase inicial que probó una vacuna terapéutica en pacientes con leucemia mieloide crónica (LMC) que tomaban el fármaco imatinib (Gleevec), no se pudieron detectar células cancerosas en 7 de los 19 participantes por un tiempo promedio de 22 meses. Los resultados del estudio fueron publicados en el número del 1º de enero de la revista Clinical Cancer Research.

337

Vacunas contra los virus del papiloma humano  

Cancer.gov

Hoja informativa acerca de las vacunas contra los virus del papiloma humano (VPH) para prevenir infecciones con ciertos tipos de VPH, los cuales son la causa principal del cáncer de cuello del útero o cérvix.

338

Siga adelante: la vida después del tratamiento del cáncer  

Cancer.gov

Consejos para supervivientes de cáncer con información sobre temas relacionados con la vida después del tratamiento, entre ellos, la atención médica de seguimiento, los cambios físicos y emocionales y los cambios en el estilo de vida.

339

Siga adelante: la vida después del tratamiento del cáncer  

Cancer.gov

E-book con consejos para supervivientes de cáncer e información sobre temas relacionados con la vida después del tratamiento, entre ellos, la atención médica de seguimiento, los cambios físicos y emocionales y los cambios en el estilo de vida.

340

Boletín del Instituto Nacional del Cáncer - 05-25-2010  

Cancer.gov

Aproximadamente 41.000 participantes en un estudio en el Reino Unido se sometieron una sola vez a una examen de detección en la parte inferior del colon mediante el uso de un sigmoidoscopio, un instrumento delgado en forma de tubo que se inserta a través del recto para buscar lesiones precancerosas o cancerosas. Este dispositivo también tiene una herramienta para extraer pólipos potencialmente precancerosos.

341

Se da a conocer el plan del Instituto Nacional del Cáncer para acelerar la investigación del cáncer  

Cancer.gov

En la 100va Reunión Anual de la Asociación Estadounidense de Investigación del Cáncer realizada en Denver, el director del Instituto Nacional del Cáncer, doctor John E. Niederhuber, dio a conocer detalles importantes, tales como financiamiento de más subvenciones, creación de una plataforma para atención personalizada del cáncer y un programa acelerado de genética del cáncer que hará avanzar la investigación oncológica en este nuevo ambiente económico.

342

MODELADO Y SIMULACION DEL SISTEMA CARDIOVASCULAR FETAL  

Microsoft Academic Search

Resumen: En el modelado fisiológico, el propósito es comprender las funciones del cuerpo humano. Con este propósito, se abordan problemas del embarazo y el parto para minimizar las cesáreas innecesarias en mujeres propensas a cursar con Sufrimiento Fetal Agudo (SFA). En el presente estudio se realizó: el Modelado Matemático del Sistema Cardiovascular Fetal (SCVF), la Simulación y Validación del SCVF.

Rubén Moreno

343

Two-dimensional cold-air cascade study of a film-cooled turbine stator blade. 4: Comparison of experimental and analytical aerodynamic results for blade with 12 rows of 0.076-centimeter-(0.030-inch-) diameter holes having streamwise ejection angles  

NASA Technical Reports Server (NTRS)

Previously published experimental aerodynamic efficiency results for a film cooled turbine stator blade are compared with analytical results computed from two published analytical methods. One method was used as published; the other was modified for certain cases of coolant discharge from the blade suction surface. For coolant ejection from blade surface regions where the surface static pressures are higher than the blade exit pressure, both methods predict the experimental results quite well. However, for ejection from regions with surface static pressures lower than the blade exit pressure, both methods predict too small a change in efficiency. The modified method gives the better prediction.

Prust, H. W., Jr.

1978-01-01

344

Antioxidantes y prevención del cáncer  

Cancer.gov

Hoja informativa acerca de los antioxidantes, sustancias que pueden proteger las células del daño causado por moléculas inestables conocidas como radicales libres. El daño de los radicales libres puede resultar en cáncer.

345

Case Study: del Amo Bioventing  

EPA Science Inventory

The attached presentation discusses the fundamentals of bioventing in the vadose zone. The basics of bioventing are presented. The experience to date with the del Amo Superfund Site is presented as a case study....

346

Alberto del Pozo  

NSDL National Science Digital Library

The Cuban Heritage Collection of the University of Miami Libraries was a recipient of 17 original illustrations by Alberto del Pozo in 1998 from the Campilli family. "The Oricha Collection" is their gift, and it contains illustrations in pen, crayon, and ink and the collection "pays homage to the primary gods and goddesses that comprise the Afro-Cuban religion of Santer'a." The "Introduction" near the top of the page, is a good place for visitors to start learning about Pozo, who was a Parson's School of Design-trained, Cuban artist who died at the age of 47. The "Biographical Sketch" is worth looking at as well. Examples of his colorful, heavily patterned and symbolism-intensive drawings of Santeria gods and goddesses can be found in the link "Gallery". The description of each drawing is given in English and Spanish. Finally, visitors interested in more information on the Santeria, can look at the "Further Readings" link for authoritative books on the subject.

347

Boletín del Instituto Nacional del Cáncer - 28 de febrero de 2012  

Cancer.gov

Los artículos originales en inglés están disponibles en las páginas del NCI Cancer Bulletin. El Boletín es una publicación del Instituto Nacional del Cáncer (NCI), una entidad gubernamental de los Estados Unidos creada en 1937.

348

Experimental determination of stator endwall heat transfer  

NASA Technical Reports Server (NTRS)

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane possage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Resutls were obtained for Reynolds numbers based on inlet velocity and axial chord between 75,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

Boyle, Robert J.; Russell, Louis M.

1989-01-01

349

Ceramic turbine stator vane and shroud support  

DOEpatents

A support system for supporting the stationary ceramic vanes and ceramic outer shrouds which define the motive fluid gas path in a gas turbine engine is shown. Each individual segment of the ceramic component whether a vane or shroud segment has an integral radially outwardly projecting stem portion. The stem is enclosed in a split collet member of a high-temperature alloy material having a cavity configured to interlock with the stem portion. The generally cylindrical external surface of the collet engages a mating internal cylindrical surface of an aperture through a supporting arcuate ring segment with mating camming surfaces on the two facing cylindrical surfaces such that radially outward movement of the collet relative to the ring causes the internal cavity of the collet to be reduced in diameter to tightly engage the ceramic stem disposed therein. A portion of the collet extends outwardly through the ring segment opposite the ceramic piece and is threaded for receiving a nut and a compression washer for retaining the collet in the ring segment under a continuous biasing force urging the collet radially outwardly.

Glenn, Robert G. (Lower Moreland Township, Montgomery County, PA)

1981-01-01

350

Experimental determination of stator endwall heat transfer  

NASA Technical Reports Server (NTRS)

Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade.

Boyle, Robert J.; Russell, Louis M.

1989-01-01

351

Simulating Nonlinear Stator Noise for Active Control  

NASA Technical Reports Server (NTRS)

This paper outlines an idea to achieve this type of active control with on-blade actuators. First, a simple analytical example demonstrates how a simple actuator could be used to nonlinearly control sound. Second, results from a realistic geometry demonstrate high amplitude vortical gusts that produce nonlinear harmonics which can destructively interfere with otherwise unattenuating (propagating) acoustical modes. We focus on the 2BPF acoustic response here to simplify the presentation and to show that nonlinear cancellation is effective on realistic blade rows, but similar simulations for higher frequencies have also been successfully completed.

Dyson. R. W.; Hixon, R.; Nallasamy, R. M.; Sawyer, S.

2003-01-01

352

Boletín del Instituto Nacional del Cáncer - 01-05-2010  

Cancer.gov

Al caminar por los pasillos del nuevo centro oncológico integral en la sede de Ciencias Médicas de la Universidad de Puerto Rico (UPR) en San Juan, uno debe mantener los ojos abiertos. La mujer que pasa caminando vigorosamente podría ser la doctora Marcia Roxana Cruz-Correa, y no debe uno perderse la oportunidad de conocerla.

353

Boletín del Instituto Nacional del Cáncer - 04-27-2010  

Cancer.gov

Cada vez es más evidente que los esfuerzos mundiales de salud de mayor éxito dependen no solo del aporte de las mentes más brillantes, sino de la colaboración entre ellas para marcar la diferencia en el escenario global. Este enfoque es el motor impulsor detrás de una asociación excepcional con el NCI, financiada en parte por Susan G.

354

La Investigación del Cáncer en América Latina  

Cancer.gov

Este programa busca fomentar los esfuerzos locales y mundiales de prevención, diagnóstico y tratamiento del cáncer facilitando la creación de una infraestructura integral para la investigación del cáncer en América Latina.

355

Instantánea del cáncer de cuello uterino  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de cuello uterino; así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

356

Instantánea del cáncer de seno (mama)  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre el cáncer de seno (mama); así como ejemplos de actividades del NCI y adelantos en la investigación de este tipo de cáncer.

357

Geología y registros magnéticos entre arroyo La Tapera y Santa Clara del Mar, Mar del Plata  

Microsoft Academic Search

Geology and magnetic records between Arroyo La Tapera and Santa Clara del Mar, Mar del Plata. Paleomagnetic studies were carried out in Pleistocene-Holocene sedimentary sequences exposed between Arroyo La Tapera and Santa Clara del Mar in Mar del Plata. The sediments exposed in the lower part of the La Tapera and Camet sections, which apparently belong to the Ensenada Formation,

Juan Carlos BIDEGAIN; Margarita L. OSTERRIETH; Adrianus J. VAN VELZEN; Yamile RICO

358

Variabilità interannuale del fi toplancton del Lago di Tovel (Trentino, Italia)  

Microsoft Academic Search

RIASSUNTO - Variabilità interannuale del fi toplancton del Lago di Tovel (Trentino, Italia) - Lo studio del fi toplancton del Lago di Tovel nel periodo 2002-2004 ha avuto come principali obiettivi l'analisi della variabilità interannuale delle dinamiche stagionali nel Bacino Principale e nella Baia Rossa, il confronto tra le associazioni fi toplanctoniche attuali e passate (prima e dopo la scomparsa

Monica TOLOTTI; Dámaso CALLIARI; Flavio CORRADINI

359

Características del desplazamiento forzado en Colombia  

Microsoft Academic Search

RESUMEN El presente estudio es una contribución a la explicación y comprensión de la problemática del desplazamiento forzado interno en Colombia, fenómeno considerado como violación masiva y múltiple de los derechos humanos, circunstancia de lesa humanidad además de ser infracción grave del Derecho Internacional Humanitario. Se identificaron los antecedentes históricos, la dinámica regional del fenómeno, la existencia de factores estructurales

Henry Fernández Pinto; JIMMY SÁNCHEZ REYEZ

2011-01-01

360

Del Mar College GIS Program  

NSDL National Science Digital Library

Del Mar College offers a comprehensive geospatial program with certificates and Associates degrees in GIS. This site includes description of the program and courses, along with further contact information. By clicking on the link for "Geographic Information Systems" you may download a PDF with information about the program.

2010-10-28

361

Los cuatro entornos del procomún  

Microsoft Academic Search

Bastan unos minutos para entender la inmensa complejidad que tiene la noción de procomún. Disponemos de muchas definiciones aceptables, aunque las más frecuentes bordean de una u otra manera el problema de la propiedad y la teoría del valor. Cuando decimos que pertenece al procomún todo cuanto es de todos y de nadie a mismo tiempo estamos pensando en un

Antonio Lafuente

362

Trasformazioni e patologie del paesaggio  

Microsoft Academic Search

\\u000a Anche il paesaggio, come vedremo, si evolve. Ma parlare oggi di evoluzione è assai problematico e quindi non si può fare a\\u000a meno di un inquadramento più generale del fenomeno. Quando oggi si parla di evoluzione si presenta sovente un quadro che,\\u000a purtroppo, non ha sempre i caratteri della scienza e un dibattito che, di conseguenza, trascina polemiche anche fra

Vittorio Ingegnoli

363

Ayuda para usar el sitio web en español del Instituto Nacional del Cáncer  

Cancer.gov

Página de guía que le permite al lector entender la forma en que está organizado el sitio web del Instituto Nacional del Cáncer (NCI), las categorías de información disponibles y las políticas que rigen este sitio web.

364

Aplicación del cálculo de las diferencias al problema del efecto de embalse  

Microsoft Academic Search

Resumen Presentamos una solución numérica del problema del efecto de embalse con ayuda de una ecuación lineal inhomogénea en diferencias finitas de primer orden, suponiendo una ley lineal del desagüe. Este método numérico es de maneje cómodo para un cálculo aproximado.

Hans Ertel

1962-01-01

365

Control del dolor: Apoyo para las personas con cáncer  

Cancer.gov

Libro sobre el control del dolor en pacientes con cáncer. Cubre los métodos y medicinas, así como los efectos físicos y emocionales del dolor. Es una adaptación cultural para el público de habla hispana del libro en inglés Pain Control.

366

Fractional Indices of Log del Pezzo Surfaces  

NASA Astrophysics Data System (ADS)

The fractional index of a (possibly singular) Q-Gorenstein del Pezzo surface X is the greatest rational number r such that -K_X\\equiv rH, where H is a primitive Cartier divisor. This paper describes the set of values taken by fractional indices of del Pezzo surfaces with log terminal singularities. Bibliography: 7 titles.

Alekseev, V. A.

1989-06-01

367

Fisiología del embarazo: Interacción materno-infantil  

Microsoft Academic Search

ResumenEn los últimos años los datos han demostrado de qué manera el bienestar vitalicio depende considerablemente del crecimiento y el desarrollo intrauterinos durante la vida dentro del útero. El crecimiento fetal puede alcanzar únicamente su potencial íntegro mediante una interacción adecuada y armonizada entre la madre, la placenta y el feto. Este delicado equilibrio puede ser alterado por varios factores

Irene Cetin; Manuela Cardellicchio

2010-01-01

368

La gestione perioperatoria del paziente diabetico  

Microsoft Academic Search

\\u000a Il continuo aumento dei pazienti diabetici che giungono all’osservazione degli anestesisti rende sempre più importante la\\u000a conoscenza delle patologie comunemente associate al diabete e delle strategie da attuare per mantenere un equilibrio glicemico\\u000a ottimale nel periodo perioperatorio.\\u000a \\u000a \\u000a Per questa ragione, dopo aver sinteticamente descritto il metabolismo del glucosio, verrà trattato in questo capitolo il problema\\u000a del corretto trattamento insulinico del

Biagio Allaria

369

Centro para la Salud Mundial del NCI  

Cancer.gov

El Centro para la Salud Mundial del NCI coordina actividades de investigación y trabaja con socios nacionales e internacionales para entender y enfrentar la carga que representa el cáncer a nivel mundial.

370

Exploración del Nuevo Laboratorio Científico de Marte  

NASA Video Gallery

Únase a Fernando Abilleira, un analista de trayectoria de la NASA para la Oficina de Exploración de Marte, y conozca las nuevas tecnologías que el nuevo robot Curiosity del Laboratorio Científico d...

371

Dust formation in Nova Del 2013  

NASA Astrophysics Data System (ADS)

We present the result of the IR photometry of Nova Del 2013 obtained at the Crimean Station (Nauchny, Ukraine) of the Sternberg Astronomical Institute. JHKLM photometry was carried out with 125-cm telescope using a InSb-photometer on:

Shenavrin, V. I.; Taranova, O. G.; Tatarnikov, A. M.

2013-09-01

372

ANÁLISIS DEL ÍNDICE DE DESARROLLO DEL GOBIERNO ELECTRÓNICO EN CUBA Y SU COMPARACIÓN CON DISTINTAS REGIONES Y PAÍSES  

Microsoft Academic Search

Se realiza un estudio comparado del grado de desarrollo del gobierno electrónico en distintas regiones y países del mundo, dedicándole una atención particular al caso Cuba. Para ello se utiliza el Índice de desarrollo de gobierno electrónico (IDGE) establecido por las Naciones Unidas. A partir de los componentes del IDGE que son, el índice de servicios en línea (ISL), el

Alejandro de Armas Suárez; Roberto de Armas Urquiza

2011-01-01

373

Manual del McVCO 1999  

USGS Publications Warehouse

El McVCO es un generador de frecuencias basado en un microcontrolador que reemplaza al oscilador controlado por voltaje (VCO) utilizado en telemetría analógica de datos sísmicas. Acepta señales de baja potencia desde un sismómetro y produce una señal subportadora modulada en frecuencia adecuada para enlaces telefónicos o vía radio a un lugar remoto de recolección de datos. La frecuencia de la subportadora y la ganancia pueden ser seleccionadas mediante un interruptor. Tiene la opción de poder operar con dos canales para la observación con ganancia alta y baja. El McVCO fue diseñado con el propósito de mejorar la telemetría analógica de las señales dentro de la Pacific Northwest Seismograph Network (PNSN) (Red Sismográfica del Noroeste del Pacífico). Su desarrollo recibió el respaldo del Programa de Geofísica de la Universidad de Washington y del "Volcano Hazards and Earthquake Hazards programs of the United States Geological Survey (USGS) (Programa de Investigaciones de Riesgos Volcánicos y Programa de Investigaciones de Riesgos Sísmicos de los EEUU). Cientos de instrumentos se han construido e instalado. Además de utilizarlo el PNSN, el McVCO es usado por el Observatorio Vulcanológico de Alaska para monitorear los volcanes aleutianos y por el USGS Volcano Disaster Assistance Program (Programa de Ayuda en las Catástrofes Volcánicas del USGS) para responder a crisis volcánicas en otros países. Este manual cubre el funcionamiento del McVCO, es una referencia técnica para aquellos que necesitan saber con más detalle cómo funciona el McVCO, y cubre una serie de temas que requieren un trato explícito o que derivan del despliegue del instrumento.

McChesney, P.J.

1999-01-01

374

La capacidad redistributiva y estabilizadora del presupuesto del gobierno central español  

Microsoft Academic Search

El objetivo de este trabajo es estimar los efectos redistributivo y estabilizador\\/asegurador del presupuesto de la Administración Pública Central española en el período 1991-1996 a nivel regional. Este análisis se lleva a cabo para el conjunto del presupuesto a través de los saldos fiscales regionales y, separadamente, para el conjunto de ingresos y gastos y sus principales categorías. La metodología

NURIA BOSCH; MARTA ESPASA; PILAR SORRIBAS

2002-01-01

375

Rapporto del Sottocomitato Ricerca del Workshop Internazionale dell'Occhio Secco (2007)  

Microsoft Academic Search

I membri del Sottocomitato Ricerca del DEWS hanno esaminato i dati in letteratura relativi meccanismi ba- se della malattia dell'occhio secco. Sono state valutate le evidenze scientifiche riguardanti il film lacrimale, la ghian- dola lacrimale primaria e le ghiandole lacrimali accessorie, gli epiteli della superficie oculare (incluse cornea e con- giuntiva), le ghiandole di Meibomio, il sistema dei dotti lacri-

Membri del Sottocomitato Ricerca; Ilene K. Gipson; Pablo Argüeso; Roger Beuerman; Stefano Bonini; Igor Butovich; Reza Dana; Darlene Dartt; Dan Gamache; Bryan Ham; Marcia Jumblatt; Donald Korb; Friederich Kruse; Yoko Ogawa; Friedrich Paulsen; Michael Stern; Deborah F. Sweeney; John Tiffany; John Ubels; Mark Willcox

376

Valoración económica del ruido: una aplicación a través del método de transferencia de beneficios  

Microsoft Academic Search

Este artículo tiene como objetivo realizar una aproximación a la valoración económica de los beneficios de la reducción del ruido generado por infraestructuras de telecomunicaciones en cuatro zonas urbanas del área metropolitana de la ciudad de Medellín (Colombia). Así, mediante el método de transferencia de beneficios, en un horizonte a perpetuidad, se obtuvo un valor económico de $79,40 millones para

Francisco Javier Correa Restrepo; Juan David Osorio Múnera; Bernardo Andrés Patiño Valencia

2011-01-01

377

Efectos del color en la aceptabilidad, artificialidad, dulzor e intensidad del sabor de bebidas lácteas  

Microsoft Academic Search

El objetivo del presente estudio es analizar el efecto de la concentración de colorantes en bebidas lác- teas (batidos de vainilla) y de los parámetros de color, pureza o c ro m a, cl a ridad y tono, sobre las ex- p e c t at ivas del grado de acep t abilidad global de dichas bebidas así como sobre

T. Coello García; C. Díaz Berciano; N. Gómez Pestaña

2000-01-01

378

Intertextual Sexual Politics: Illness and Desire in Enrique Gomez Carrillo's "Del amor", "del dolor y del vicio" and Aurora Caceres's "La rosa muerta"  

ERIC Educational Resources Information Center

This study explores the intertextuality between Aurora Caceres's "La rosa muerta" (1914) and the novel "Del amor, del dolor y del vicio" (1898) by her ex-husband, Enrique Gomez Carrillo. Caceres strategically mentions Gomez Carrillo's novel in "La rosa muerta" to invite a reading of her work in dialogue with his. Both narratives follow the sexual…

LaGreca, Nancy

2012-01-01

379

Comportamento del rame OFHC in acqua di elevata purezza. (Behaviour of OFHC copper in highly pure water).  

National Technical Information Service (NTIS)

In order to gain a wider knowledge of corrosion phenomena in OFHC (oxygen free high conductivity) copper pipes of the stator cooling circuit of a power plant turboalternator, a research program was laid out which is based on the use of an experimental loo...

G. Perboni G. Rocchini G. Brunoro G. Trabanelli

1991-01-01

380

Extensión del Formalismo de Orbitales de Defecto Cuántico al tratamiento del efecto Stark (SQDO).  

NASA Astrophysics Data System (ADS)

El estudio experimental de las interacciones de átomos Rydberg altamente excitados con campos eléctricos ha experimentado un creciente interés durante las dos últimas décadas debido, en gran medida, al desarrollo de nuevas técnicas para crear y estudiar átomos Rydberg en el laboratorio. Acompañando a estas nuevas técnicas experimentales, es necesario el desarrollo de modelos teóricos que nos permitan contrastar sus medidas y conocer mejor los fundamentos de los mismos. Desde el punto de vista teórico el conocimiento del desdoblamiento de los niveles energéticos de un átomo en función de la magnitud del campo eléctrico aplicado (lo que se conoce como mapa Stark) es el mejor punto de partida para la descripción del sistema y un prerrequisito fundamental para el cálculo de distintas propiedades atómicas en presencia del campo eléctrico tales como intensidades de transición, umbrales de ionización de campo eléctrico, tiempos de vida, posición y anchura de cruces evitados, etc. En este trabajo presentamos la adaptación del método de orbitales de defecto cuántico [1,2,3] al tratamiento del efecto Stark (SQDO) [4] y su aplicación al cálculo de los desdoblamientos energéticos y fuerzas de oscilador de estados Rydberg en los átomos de Li, Na y K. El propósito de este estudio es, por un lado, desarrollar métodos fiables para la determinación de propiedades atómicas en presencia de campos eléctricos y, por otro, mostrar la fiabilidad de las funciones de onda QDO en la descripción del efecto Stark en sistemas atómicos.

Menéndez, J. M.; Martín, I.; Velasco, A. M.

381

El Servicio de Información sobre el Cáncer del Instituto Nacional del Cáncer  

Cancer.gov

El Servicio de Información del Cáncer (CIS) del Instituto Nacional del Cáncer facilita la información más actualizada y precisa sobre el cáncer a pacientes, a sus familias, al público en general y a profesionales médicos. El CIS brinda respuestas personalizadas a preguntas específicas sobre el cáncer y asistencia a los fumadores que quieren abandonar el hábito. Comuníquese con el CIS al 1-800-422-6237 (1-800-4-CANCER) o al 1-877-448-7848 (1-877-44U-QUIT).

382

La reconstrucción del seno después de una mastectomía  

Cancer.gov

Hoja informativa que describe la reconstrucción del seno (mama) después de una mastectomía. Contiene información sobre las opciones quirúrgicas, los cuidados de seguimiento y los exámenes de detección del cáncer de seno después de la reconstrucción.

383

Transformación de los programas de estudios clínicos del NCI  

Cancer.gov

Información sobre los programas e iniciativas del NCI que patrocinan, realizan, crean o apoyan estudios clínicos, entre los que se incluyen la Red Nacional de Estudios Clínicos (NCTN) y el Programa de Investigación Oncológica Comunitaria (NCORP) del NCI.

384

Exportaciones del Sector Maderas y Papeles No Tradicional  

Microsoft Academic Search

fueron México (23.0% % de participación), Estados Unidos (15.4%), China (15.1%), Venezuela (8.2%) y Ecuador (8.1%). En conjunto estos cinco países concentraron el 66.8.0% del total de exportaciones del sector. Las ventas hacia los mercados de México, China, Ecuador y Venezuela, fueron superiores a las registradas en el mismo periodo del 2007, creciendo durante los primeros seis meses del año

Millones FOB

385

33 CFR 80.1118 - Marina Del Rey, CA.  

Code of Federal Regulations, 2013 CFR

...1 2013-07-01 2013-07-01 false Marina Del Rey, CA. 80.1118 Section 80.1118 Navigation and Navigable Waters...DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South...

2013-07-01

386

Boletín del Instituto Nacional del Cáncer - 8 de noviembre de 2011  

Cancer.gov

Le invitamos a que comparta esta publicación con sus amigos, familiares y colegas y nos ayude a continuar nuestra misión de difundir las investigaciones más recientes sobre la prevención, el tratamiento y la información del cáncer.

387

Impacto del conflicto colombiano en los periodistas  

Microsoft Academic Search

Introducción: Este artículo esboza las dificultades que presentan los periodistas colombianos en su trabajo y caracteriza el impacto del conflicto armado colombiano en su relación con este ejercicio profesional. Método: Los autores realizaron 70 entrevistas a algunos periodistas colombianos que cubren el conflicto. Para el análisis de las entrevistas se intentó entender la lógica de su conducta y cómo representan

Ismael Roldán; Diana Sofía Giraldo; Miguel Ángel Flórez

2008-01-01

388

Exámenes selectivos de detección del cáncer colorrectal  

Cancer.gov

Un ejemplo excelente del poder de la investigación de prevención es el progreso sustancial que hemos logrado en la reducción de la incidencia y muerte por cáncer colorrectal, con nuevos conocimientos que iluminan el camino a incluso mayores reducciones en un futuro cercano.

389

Vigilando la Calidad del Agua de los Grandes Rios de la Nacion: El Programa NASQAN del Rio Grande (Rio Bravo del Norte)  

USGS Publications Warehouse

La Oficina del Estudio Geologico de los Estados Unidos (U.S. Geological Survey, 0 USGS) ha monitoreado la calidad del agua de la cuenca del Rio Grande (Rio Bravo del Norte) desde 1995 como parte de la rediseiiada Red Nacional para Contabilizar la Calidad del Agua de los Rios (National Stream Quality Accounting Network, o NASOAN) (Hooper and others, 1997). EI programa NASOAN fue diseiiado para caracterizar las concentraciones y el transporte de sedimento y constituyentes quimicos seleccionados, encontrados en los grandes rios de los Estados Unidos - incluyendo el Misisipi, el Colorado y el Columbia, ademas del Rio Grande. En estas cuatro cuencas, el USGS opera actualmente (1998) una red de 40 puntos de muestreo pertenecientes a NASOAN, con un enfasis en cuantificar el flujo en masa (la cantidad de material que pasa por la estacion, expresado en toneladas por dial para cada constituyente. Aplicacando un enfoque consistente, basado en la cuantificacion de flujos en la cuenca del Rio Grande, el programa NASOAN esta generando la informacion necesaria para identificar fuentes regionales de diversos contaminantes, incluyendo sustancias qui micas agricolas y trazas elementos en la cuenca. EI efecto de las grandes reservas en el Rio Grande se puede observar segun los flujos de constituyentes discurren a 10 largo del rio. EI analisis de los flujos de constituyentes a escala de la cuenca proveera los medios para evaluar la influencia de la actividad humana sobre las condiciones de calidad del agua del Rio Grande.

Lurry, Dee L.; Reutter, David C.; Wells, Frank C.; translated by Rivera, M.C.; Munoz, A.

1998-01-01

390

Boletín del Instituto Nacional del Cáncer - 31 de enero de 2012  

Cancer.gov

Dr. Nils Daulaire Salud mundial a través de la colaboración y el liderazgo Para conmemorar el Día Mundial del Cáncer que tuvo lugar el 4 febrero, el doctor Nils Daulaire, director de la Oficina de Asuntos Internacionales del Departamento de Salud y Servicios Humanos de los Estados Unidos habla sobre las razones por las cuales los Estados Unidos deben participar en iniciativas para mejorar la salud mundial.

391

Comportamiento del Helio en estrellas químicamente peculiares  

NASA Astrophysics Data System (ADS)

Las estrellas químicamente peculiares (CP) se caracterizan por tener deficiencias y sobreabundancias de algunos elementos químicos de hasta 106 veces la abundancia solar. Además presentan variaciones en las líneas espectrales. Se piensa que ello se debe a que los campos magnéticos presentes en este tipo de estrellas son principalmente dipolares, con un eje de simetría diferente del eje de rotación. La distribución de los elementos sobreabundantes y deficientes no es homogénea sobre la superficie estelar y las variaciones observadas serían una consecuencia directa de la rotación estelar. Entre los elementos con abundancia anómala se encuentra el Helio, cuyas líneas tienen intensidades que no son consistentes con una abundancia normal, que no puede ser determinada del modo usual, o sea, considerando una atmósfera con composición solar. Con el fin de determinar la abundancia de este elemento, se inició un estudio de estrellas anómalas de Helio, Hew y He strong. Además se determinarán las abundancias de otros elementos anómalos como ser el Si, Cr, Mg, Mn y Fe. Las mismas se determinan del modo tradicional, o sea: a) medida de los anchos equivalentes de las líneas de los distintos elementos analizados; b) adopción de la temperatura efectiva, gravedad y abundancia del Helio; c) cálculo del modelo de atmósfera d) comparación con las observaciones y reinicio de un proceso iterativo hasta lograr un acuerdo entre todos los parámetros analizados. Las observaciones se llevaron a cabo en el Complejo Astronómico El Leoncito. Se observaron setenta y ocho estrellas anómalas de Helio. En este momento se está procediendo a calcular las abundancias correspondientes a los distintos elementos químicos. Para ello se hace uso de los modelos de Kurucz, ATLAS9. Los cálculos NLTE de las líneas de Helio se llevan a cabo con el programa MULTI y se compararán con los realizados con el programa WIDTH9 de Kurucz (LTE), con el objeto de resaltar la importancia de los efectos NLTE.

Malaroda, S. M.; López García, Z.; Leone, F.; Catalano, F.

392

[Orientamento religioso e disturbi del comportamento alimentare].  

PubMed

riassunto. Introduzione. L'obiettivo principale del presente studio caso-controllo è stato quello di valutare le relazioni intercorrenti tra la psicopatologia dei disturbi del comportamento alimentare (DCA) con il differente orientamento religioso: intrinseco ed estrinseco. Metodi. Sono stati confrontati un gruppo di pazienti affetti da DCA (23 con anoressia nervosa, 10 con bulimia nervosa e 39 con disturbo d'alimentazione incontrollata) con un gruppo di controllo di soggetti sani, utilizzando la Religious Orientation Scale (ROS). Risultati. I pazienti affetti da DCA hanno mostrato punteggi più alti nella sottoscala della religiosità estrinseca e minori punteggi nella sottoscala riguardante la religiosità intrinseca rispetto ai controlli sani. Nessuna differenza significativa è stata osservata tra i gruppi di DCA in termini di punteggi ROS. Conclusioni. Punteggi più elevati riscontrati in pazienti con orientamento religioso estrinseco sembrano essere associati con la presenza di DCA, mentre un orientamento religioso di tipo intrinseco sembra rappresentare un fattore protettivo. PMID:25000890

Castellini, Giovanni; Zagaglioni, Alice; Godini, Lucia; Monami, Francesca; Dini, Carla; Faravelli, Carlo; Ricca, Valdo

2014-01-01

393

Del Norte means north to recycling  

SciTech Connect

Del Norte Regional Recycling and Transfer Station is owned by the city of Oxnard, California and operated by BLT Enterprises, Inc. The Del Norte facility--located in southwestern Ventura County about an hour northwest of Los Angeles--processes polyethylene terephthalate (PET) and high-density polyethylene (HDPE) plastic containers, aluminum, steel, glass, old corrugated containers (OCC), newspapers, computer printout paper, white and colored ledger paper, coated book, supermix paper, telephone books, and old magazines. According to the company, there has been virtually no community opposition to the site. The facility has few neighbors, and those are agricultural. To keep the community relationship strong, the facility`s design and location all but eliminated odor and noise complaints. The building was designed against the prevailing wind pattern, and BLT processes odorous material fast. A misting system installed for dust suppression also can be used with a solution for odor control should the need arise.

Aquino, J.T.

1998-06-01

394

Turbine rotor-stator leaf seal and related method  

DOEpatents

A seal assembly for installation between rotating and stationary components of a machine includes a first plurality of leaf spring segments secured to the stationary component in a circumferential array surrounding the rotating component, the leaf spring segments each having a radial mounting portion and a substantially axial sealing portion, the plurality of leaf spring segments shingled in a circumferential direction.

Herron, William Lee (Cincinnati, OH); Butkiewicz, Jeffrey John (Simpsonville, SC)

2003-01-01

395

Flow Coupling Between a Rotor and a Stator in Turbomachinery.  

National Technical Information Service (NTIS)

Successful turbomachine design requires detailed information about flow characteristics in order to predict the performance of a candidate geometry. The design needs information about the complex interaction between the blade rows when multistage blade ro...

I. C. Jiang T. W. Bein Y. T. Lee

1990-01-01

396

Advanced 3-D viscous SSME turbine rotor stator CFD algorithms  

NASA Technical Reports Server (NTRS)

Current Space Shuttle Main Engine (SSME) high pressure fuel turbopump problems have generated a desire to analyze the flow field of rotating machinery. The status of Computational Fluid Dynamics (CFD) has reached the point that soon the capability to solve unsteady three-dimensional viscous flow fields will be at hand. The work presented involves upgrading the computational efficiency of an operational three-dimensional algorithm. The modifications include algorithm development, algorithm approximation and acceleration, and special coding optimizations. The overall result of these modifications has reduced processing time by nearly 80%.

Janus, J. Mark; Whitfield, David L.

1986-01-01

397

Voltage endurance test facility for electric generator stator coils  

Microsoft Academic Search

The development of new coil designs with the use of updated materials and\\/or processes requires voltage endurance testing as one of the tests to verify the new coil design. From established voltage endurance curves, a new insulation system can be evaluated against accepted coil designs. An expanded voltage endurance test lab has been developed which has the capabilities for testing

F. T. Emery; R. F. Weddleton

1993-01-01

398

Stator for a rotating electrical machine having multiple control windings  

DOEpatents

A rotating electric machine is provided which includes multiple independent control windings for compensating for rotor imbalances and for levitating/centering the rotor. The multiple independent control windings are placed at different axial locations along the rotor to oppose forces created by imbalances at different axial locations along the rotor. The multiple control windings can also be used to levitate/center the rotor with a relatively small magnetic field per unit area since the rotor and/or the main power winding provides the bias field.

Shah, Manoj R. (Latham, NY); Lewandowski, Chad R. (Amsterdam, NY)

2001-07-17

399

Multifactor aging of HV generator stator insulation including mechanical vibrations  

Microsoft Academic Search

The long-term behavior of solid electrical insulation is influenced by the nature and the magnitude of applied stresses. Much work has been done over the years to model and understand insulation degradation under single and combined electric and thermal stresses. However, efforts aimed at including mechanical stress as an additional interactive aging term in the existing models appear to be

M. B. Srinivas; T. S. Ramu

1992-01-01

400

Motor bearing damage detection using stator current monitoring  

Microsoft Academic Search

This paper addresses the application of motor current spectral analysis for the detection of rolling-element bearing damage in induction machines. Vibration monitoring of mechanical bearing frequencies is currently used to detect the presence of a fault condition. Since these mechanical vibrations are associated with variations in the physical air gap of the machine, the air gap flux density is modulated

Randy R. Schoen; Thomas G. Habetler; Farrukh Kamran; R. G. Bartfield

1995-01-01

401

Enfoques de programación matemática fuzzy multiobjetivo para la planificación operativa del transporte en una cadena de suministro del sector del automóvil = Fuzzy Multiobjective Mathematical Programming Approaches for Operational Transport Planning in an Automobile Supply Chain  

Microsoft Academic Search

En este trabajo se presenta un modelo de programación matemática fuzzy multiobjetivo para la planificación del transporte a nivel operativo en una cadena de suministro. Los objetivos del modelo propuesto son la minimización del número de camiones utilizados y del inventario total, considerando como parámetro borroso las capacidades de los vehículos empleados. Se propone una metodología de resolución para transformar

Manuel Díaz-Madroñero; David Peidro; Josefa Mula; Francisco J. Ferriols

2010-01-01

402

SISTEMA PARA GESTIONAR LA ACTIVIDAD CIENTÍFICA DEL DEPARTAMENTO DE INFORMÁTICA DE LA UNIVERSIDAD DE GUANTÁNAMO  

Microsoft Academic Search

El sistema para gestionar la actividad científica del Departamento de Informática de la Universidad de Guantánamo surge debido a la necesidad de gestionar de manera más rápida, segura y eficaz los procesos que se desarrollan actualmente en dicho centro. Fue desarrollado utilizando los lenguajes PHP del lado del servidor con CodeIgniter como framework y JavaScript del lado del cliente. Se

Denis Boizan Romero

2012-01-01

403

Laser doppler velocimetry measurements in a one and a half stage transonic test turbine with different angular stator stator positions  

Microsoft Academic Search

Metal insulator metal (M I M) structures involving transition-metal oxides and, more recently, also perovskite oxides with resistive switching effects have attracted substantial interest in research aimed at nonvolatile memories of nanometer dimensions. Although some models are presently under discussion, it is still not clear whether the fundamental switching mechanism is an interface or a bulk property, or a combination

Oliver Schennach; Jakob Woisetschläger; Andreas Marn; Emil Göttlich

2007-01-01

404

Epidemiologia della malattia dell'Occhio Secco: Rapporto del Sottocomitato Epidemiologia del Workshop Internazionale dell'Occhio Secco (2007) Epidemiologia  

Microsoft Academic Search

Il rapporto del Sottocomitato Epidemiologia del Workshop dell'Occhio Secco del 2007 riassume le cono- scenze attuali dell'epidemiologia della malattia dell'occhio secco, fornendo i dati di prevalenza e incidenza derivanti da varie popolazioni. Mette in risalto la necessità di allargare gli studi epidemiologici a ulteriori aree geografiche, di incorpo- rare varie razze ed etnie negli studi futuri e di determinare un

Sottocomitato Epidemiologia; Janine A. Smith; Julie Albeitz; Carolyn Begley; Barbara Caffery; Kelly Nichols; Debra Schaumberg; Oliver Schein

405

Descripción del funcionamiento del mercado secundario de bonos soberanos locales en Chile  

Microsoft Academic Search

En este trabajo se describe el funcionamiento del mercado secundario de los bonos de largo plazo soberanos locales. Más específicamente, se describen en profundidad los agentes involucrados, los instrumentos transados y los tipos de plataformas existentes. A partir de este trabajo es posible obtener las siguientes conclusiones. Primero, existe un alto grado de segmentación en el mercado secundario de renta

Sergio D’Acuña; Sergio Godoy; Nicolás Malandre

2009-01-01

406

Eficiencia y determinantes del funcionamiento del mercado paralelo de divisas en Colombia  

Microsoft Academic Search

El presente trabajo analiza la relación entre el tipo de cambio negro y el oficial, al igual que la eficiencia del mercado paralelo de divisas en Colombia. Con base en datos mensuales para el período 1970-1989, se encontró que la tasa de cambio oficial y paralela estaban cointegradas, lo cual implica que el dólar oficial y el negro mantuvieron una

Santiago Herrera

1990-01-01

407

Ajuste estructural y mercado del trabajo: Nigeria después de la crisis del petróleo  

Microsoft Academic Search

En este artículo examinamos la experiencia de Nigeria durante la crisis petrolera de los años 1980 y el comienzo de la aplicación de un paquete de ajuste estructural. Nuestro análisis se concentra en el rol jugado por el mercado del trabajo, particularmente en relación a la situación de empleo y desempleo, como también a los flujos migratorios despertados por la

Paul Collier; Luis Riveros

408

Mujeres en ascenso: dinámica del sistema educativo y del mercado laboral en Colombia, 1900-2000  

Microsoft Academic Search

El objetivo principal de la presente investigación es describir y analizar los cambios en la transmisión de conocimiento en los establecimientos educativos femeninos de Bogotá y la participación de la mujer dentro del mercado laboral bogotano. Con base en los resultados que arrojó la Encuesta de empleo de 1963-1970 para Bogotá y la Encuesta Integrada de hogares 2006, se elaboró

María del Pilar López-Uribe; Diana Quintero Castellanos; Loly Aylú Gaitán Guerrero

2011-01-01

409

La quimera del mezzo termine. La contribución franco-británica a la caída del liberalismo peninsular  

Microsoft Academic Search

En 1823, en un contexto marcado por el temor a despertar del fantasma de la revolución en Europa, pasó a un primer plano la posibilidad de ensayar en la Península fórmulas moderadas de organización política, un mezzo termine que conjugara la renuncia a los principios más revolucionarios con el reconocimientos de ciertos derechos y garantías individuales. El debate creado en

Gonzalo Butrón Prida

2001-01-01

410

Boletín del Instituto Nacional del Cáncer - 11 de septiembre de 2012  

Cancer.gov

Con la ayuda de herramientas genéticas, investigadores han identificado subconjuntos de células que parecen impulsar el crecimiento de tumores en ratones. Estos resultados ofrecen factores adicionales que sustentan la hipótesis de la existencia de células madre del cáncer, es decir, la idea de que algunos tumores contienen células que se autorenuevan y dan origen a todo tipo de células tumorales.

411

Diseño del saneamiento de Urdaibai (País Vasco) bajo una perspectiva de preservación ambiental del litoral  

Microsoft Academic Search

Los sistemas de saneamiento unitarios, del mismo modo que cualquier obra de infraestructura dispuesta a soportar fenómenos naturales, pre- sentan, inevitablemente, una determinada probabilidad de fallo, igual, a la de que los efectos producidos por estos superen a los considerados en su diseño. Por tanto, el comportamiento general de los mismos sólo puede evaluarse en términos probabilísticos. Siendo la lluvia

ANDRÉS GARCÍA; KALIN N. KOEV; JOSÉ A. REVILLA; JOSÉ A. JUANES

412

Alcune osservazioni sulle cause di tenuta del settore del franchising nelle fasi recessive  

Microsoft Academic Search

La ricerca esamina le imprese che operano in franchising attraverso microdati raccolti da Assofranchising, la principale associazione italiana nel campo del franchising. Mediante tecniche esplorative e multivariate si dimostra che, ceteris paribus, un aumento della scala delle reti, basata sulla crescita delle risorse umane e materiali, ha un effetto positivo sull’efficienza aziendale attraverso il miglioramento di indicatori strategici di produttività.

Antonio Bernardi

2011-01-01

413

Tratamiento adyuvante del carcinoma de recto  

Microsoft Academic Search

Resumen\\u000a Objectivo  Neustro objetivo es analizar los resultados del tratamiento adyuvante en pacientes operados por un carcinoma rectal localmente\\u000a avanzado, tratados con radioquimioterapia concomitante o secuencial.\\u000a \\u000a \\u000a \\u000a Material y métodos  Entre enero de 1994 y septiembre de 1997, 122 pacientes fueron tratados postquirúrgicamente por un adenocarcinoma rectal en\\u000a estadio B2-C. Setenta y siete pacientes fueron tratados siguiendo un esquema alternante de quimiorradioterapia y

Javier Valencia Julve; Ricardo Escó Barón; Javier Sanz Lacalle; Miguel Burillo Cordero; Pedro Mateo de las Heras; Carmen Lainez Baquero

2003-01-01

414

UBVJHKLM photometry of Nova Del 2013  

NASA Astrophysics Data System (ADS)

We present the results of the optical and IR photometry of Nova Del 2013 obtained at the Crimean Station (Nauchny, Ukraine) of the Sternberg Astronomical Institute. UBV photometry was carried out with 60-cm Zeiss telescope using a photoelectric photometer on August 15.94 UT: U=4.54+/-0.02, B=5.07+/-0.01, V=5.05+/-0.01; on August 16.80 UT: U=4.54+/-0.01, B=4.85+/-0.02, V=4.68+/-0.01; on August 16.86 UT: U=4.66+/-0.01, B=4.92+/-0.01, V=4.73+/-0.01.

Burlak, A. M.; Shenavrin, I. V.; Tatarnikov, M. A.; Tatarnikova, A. A.

2013-08-01

415

TEMA V TENDENCIAS RECIENTES EN EL MERCADO DE TRABAJO (I): LA CONSTRUCCIÓN SOCIOHISTÓRICA DEL MERCADO DE TRABAJO CONTEMPORÁNEO: DEL FORDISMO AL POSFORDISMO  

Microsoft Academic Search

Este tema presenta un conjunto de cuestiones relacionadas con las transformaciones históricas más recientes del trabajo y del empleo. Intentaremos aquí seguir su trayectoria en la segunda mitad del siglo XX para poder analizar las tendencias más recientes del mercado de trabajo que se proyectan hacia el siglo XXI y que sirven de contexto y de marco de explicación al

Antonio Santos Ortega

416

MÚSICA Y AGRUPACIONES DE CARNAVAL A FINALES DEL SIGLO XX EN ANDALUCÍA OCCIDENTAL. LA REVITALIZACIÓN FESTIVA Y EL RENACIMIENTO DEL CARNAVAL  

Microsoft Academic Search

Con este trabajo pretendemos acercarnos al Carnaval de Andalucía occidental a partir de su recuperación durante la Transición y los gobiernos socialistas en la década de los años ochenta del pasado siglo XX. Este proceso tuvo lugar en un marco de participación ciudadana, modernización económica, estado del bienestar, constitución de las comunidades autónomas, sociedad del espectáculo y del entretenimiento, y

Francisco José García Gallardo

2005-01-01

417

Instantánea de los cánceres de cerebro y del sistema nervioso central  

Cancer.gov

Información sobre las tendencias de incidencia, mortalidad y financiamiento del NCI sobre los cánceres de cerebro y del sistema nervioso central; así como ejemplos de actividades del NCI y adelantos en la investigación de estos tipos de cáncer.

418

Decoding F508del Misfolding in Cystic Fibrosis  

PubMed Central

The functional deficiency of the cystic fibrosis transmembrane conductance regulator (CFTR), a plasma membrane chloride channel, leads to the development of cystic fibrosis. The deletion of a phenylalanine at residue 508 (F508del) is the most common cause of CFTR misfolding leading to the disease. The F508del misfolding originates in the first nucleotide-binding domain (NBD1), which induces a global conformational change in CFTR through NBD1’s interactions with other domains. Such global misfolding produces a mutant chloride channel that is impaired in exocytic trafficking, peripheral stability, and channel gating. The nature and atomic details of F508del misfolding have been subject to extensive research during the past decade. Current data support a central role for NBD1 in F508del misfolding and rescue. Many cis-acting NBD1 second-site mutations rescue F508del misfolding in the context of full-length CFTR. While some of these mutations appear to specifically counteract the F508del-induced misfolding, others release certain inherent conformational constraints of the human wild-type CFTR. Several small-molecule correctors were recently found to act on key interdomain interfaces of F508del CFTR. Potential rational approaches have been proposed in an attempt to develop highly effective small molecule modulators that improve the cell surface functional expression of F508del CFTR.

Wang, Xiaodong Robert; Li, Chenglong

2014-01-01

419

Conceptos fundamentales del desarrollo de proveedores (Caso de negocios 13)  

Microsoft Academic Search

El desarrollo de proveedores es una actividad que enriquece la gestión de la cadena de suministro, dotándola de mayor valor a través del aporte mutuo entre empresas clientes y subcontratistas. Este aporte incluye nuevas tecnologías, know-how, herramientas de la calidad y organización del trabajo, además de negociaciones sobre la política de precios, entre otros temas. En este trabajo presentamos sus

Enrique Yacuzzi

2012-01-01

420

Fomento de la investigación del cáncer en América Latina  

Cancer.gov

La Oficina para el Desarrollo de Programas de Cáncer en América Latina (OLACPD), fruto de una alianza innovadora entre el Instituto Nacional del Cáncer (NCI) y el Centro Internacional Fogarty (FIC), fue creada en reconocimiento de la oportunidad de apoyar y mejorar la investigación y el tratamiento del cáncer en América Latina.

421

El presidente Obama anuncia nombramiento del doctor Harold Varmus  

Cancer.gov

En los últimos cinco años como director del NCI, y en otras funciones ejercidas durante muchos años, he disfrutado ampliamente cada oportunidad que he tenido de visitar los laboratorios y las oficinas, desde Bethesda hasta Frederick, para conocer en persona a los miembros del personal y compartir mis opiniones sobre temas importantes en torno a la ciencia y al manejo de este gran Instituto.

422

El sistema muscular es el impulsor del desarrollo esquelético  

Microsoft Academic Search

ExtractoEn esta revisión se abordan los conceptos metodológicos de evaluación de la función de la musculatura esquelética y adaptación ósea. Actualmente se considera que la propiedad crítica del hueso no es tanto su peso como su resistencia, y que el control de la resistencia ósea se ejerce principalmente a través del efecto de las cargas mecánicas que inciden sobre el

Eckhard Schoenau

2006-01-01

423

The hydrothermal system of Nevado del Ruiz volcano, Colombia  

Microsoft Academic Search

Hot springs and steam vents on the slopes of Nevado del Ruiz volcano provide evidence regarding the nature of hydrothermal activity within the summit and flanks of the volcano. At elevations below 3000 m, alkali-chloride water is discharged from two groups of boiling springs and several isolated warm springs on the western slope of Nevado del Ruiz. Chemical and isotopic

Neil C. Sturchio; Stanley N. Williams; Nestor P. Garcia; Adela C. Londono

1988-01-01

424

Gestión ambiental de la vitivinicultura: aplicación del cuadro de mando  

Microsoft Academic Search

Resumen La vitivinicultura es una de las principales industrias de San Juan, Argentina. En esta provincia existen más de 266 bodegas. Actualmente, existe mayor conciencia, por parte del consumidor, del proceso de elaboración de un producto, desde el punto de vista medioambiental, sobre todo en países como Estados Unidos y el Reino Unido, los cuales son los principales países importadores

Rosa Ana Rodríguez; Gustavo R. Traconis

2012-01-01

425

An Accretion Disc Model For Eclipsing Binary System: AV Del  

Microsoft Academic Search

We investigate the light and radial-veloci -ty curves of the eclipsing binary AV Del. Using the most new version of Wilson & Van Hamme (2003) code, the absolute elements, fundamental orbital and physical parameters of the system are determined. Then, using the new SHELLSPEC code, we study and present an accretion disc model for the system. We found AV Del

Sayyed Mohammad Reza Ghoreyshi; Jamshid Ghanbari; Fatemeh Salehi

426

Molecular basis of DEL phenotype in the Chinese population  

PubMed Central

Background Rh blood group system is the most complex and immunogenetic blood group system. Prevalent RHD alleles vary in different populations. We conducted the present study to examine the genotype of DEL individuals and to elucidate whether novel alleles exist in the Chinese population. Methods DEL phenotype was identified by a serologic adsorption-elution method. The nucleotide sequences of ten RHD exons and exon-intron boundary regions were evaluated by RHD gene-specific PCR-SSP and sequencing. Results Of 42306 samples from individual donors and patients, 165 samples were typed as D-negative. Among these D-negative samples, 41 DEL individuals were observed. Thirty-seven DELs were confirmed to have the RHD1227A allele. Two DELs seemed to have RHD-CE-D hybrid alleles, including one RHD-CE (4–7)-D and one RHD-CE (2–5)-D. Two novel RHD alleles were found among the rest of the DEL samples, including one RHD93T?>?A and one RHD838G?>?A. Conclusion In this study, about 24.85% (41/165) of the apparent D-negative Chinese individuals were DEL. RHD1227G?>?A is the most frequent allele in Chinese DEL phenotypes, accounting for 90.24% (37/41). The RHD-CE-D hybrid allele might be the second most frequent DEL allele in the Chinese population. Our study would contribute to the understanding of the molecular mechanism underlying D antigen expression of DEL individuals and provide useful information for designing suitable genotyping strategies in RhD-negative individuals in Asia.

2014-01-01

427

El Instituto Nacional del Cáncer de EE. UU. y la República del Perú firman una Declaración de Intención  

Cancer.gov

El Instituto Nacional del Cáncer y la República del Perú firmaron una declaración de intención para compartir el interés en fomentar la investigación biomédica de oncología, basándose en la colaboración mutua de ambas entidades, así como el objetivo común de educar y capacitar la futura generación de científicos y clínicos en investigación oncológica.

428

La dimensione del tumore è predittiva della sopravvivenza nel tumore del polmone non a piccole cellule in stadio IA  

Microsoft Academic Search

Oggetto dello studio: La premessa base dello screening mediante TC è che la dimensione sia una determinante importante della sopravvivenza per il cancro del polmone. Noi abbiamo cer- cato di esaminare questa ipotesi per il tumore del polmone non a piccole cellule (NSCLC) in stadio IA. Metodi: È stata condotta una analisi retrospettiva di tutti i pazienti con NSCLC istologicamente

Jeffrey L. Port; Michael S. Kent; Robert J. Korst; Daniel Libby; Mark Pasmantier; Nasser K. Altorki

2004-01-01

429

[Strengths and future of the Revista Médica del Instituto Mexicano del Seguro Social].  

PubMed

The journals of medicine arose as a communication tool more than 200 years ago. At the beginning, their nature was local; later, their aim was to spread medical information along the nation; and, finally, they sought to reach the world distribution. The Revista Médica del Instituto Mexicano del Seguro Social was published for the first time 52 years ago, and it has walked its way from local to international distribution. This journal has 23 000 subscribers, it is included in Medline and it reached a 0.112 SCImago Journal Rank in 2012. Its website receives around 200 000 visits monthly and 45 % are foreign visits. In the future, the peer review system is going to be strengthened, and the journal is going to offer audio, video, and applications to reinforce interactive participation between authors, readers in order to reach modernity and draw young new attention. PMID:24758842

Fajardo-Dolci, Germán

2014-01-01

430

O Diagnostico do Curso de Farmacia da UNIMEP (Diagnosis of the Pharmacy Course of UNIMEP).  

ERIC Educational Resources Information Center

Reports on the experience of the pharmacy course at UNIMEP (Methodist University of Piracicaba (Brazil)) in diagnosing itself. Offers models for the elaboration of an innovative curriculum which is the desire of those who make up the course. (BT)

Fontes, Olney Leite; do Carmo, Thais Adriana; Polacow, Maria Luiza O.; Meneghetti, Rosa Gitana K.; Dedalo, Maria de Fatima Nepomuceno; Alves, Maria Izalina F.; da Silva, Jadson Oliveira; Carvalho, Maria Eliza C.

2000-01-01

431

El metabolismo social del País Vasco desde el análisis de flujos materiales  

Microsoft Academic Search

La desvinculación de la mejora del bienestar respecto del uso de los recursos y de la contaminación es esencial para lograr un desarrollo sostenible. Para avanzar en esta dirección es preciso partir del conocimiento del metabolismo de la sociedad. Es decir, debemos analizar en qué medida nuestras sociedades “ingieren” materias primas, que son “metabolizadas” para producir bienes y servicios, y

Iñaki Arto

2009-01-01

432

La teoría de juegos conductual, el dilema del viajero alternativo y la maximización de pagos  

Microsoft Academic Search

Dentro del área de teoría de juegos conductual nos enfocamos en un contexto específico, el del juego que denominamos Dilema del viajero alternativo. En este contexto hemos observado que los participantes tienden a elegir estrategias estrictamente dominadas. Para explicar tendencias similares en otros juegos, los investigadores del área han apelado a sesgos cognitivos o bien a factores motivacionales. Proponemos un

Rodrigo Moro; Esteban Freidin; Fernando Tohmé; Marcelo Auday

433

Doctor Harold Varmus, director del NCI: Bienvenidos a Cancer.gov en español  

Cancer.gov

El director del NCI, doctor Harold Varmus, da la bienvenida a los visitantes al sitio web del NCI y habla sobre la complejidad del cáncer, así como de los avances alcanzados gracias a las nuevas herramientas y tecnologías para la investigación del cáncer.

434

Antenatal Rh prophylaxis is unnecessary for “Asia type” DEL women  

Microsoft Academic Search

BackgroundGenerally Rh-negative patients need to be transfused with Rh-negative red blood cells. For pregnant women carrying Rh-positive fetus, the antenatal anti-D detection and Rh immunoglobulin prophylaxis are required worldwide. In East Asia, a RhD variant, termed “Asia type” DEL, was found in approximately 30% of apparent Rh-negative individuals. The antigenic and molecular properties of the DEL were previously defined. Few

Chao-Peng Shao; Hua Xu; Qun Xu; Guo-Dong Sun; Jian-Ping Li; Bo-Wei Zhang; Xiao-Hua Liang; Zhong Liu; Ying Zhou; Dan Li; Nai-Bao Zhuang

2010-01-01

435

Modelo semi-empírico de protuberancia solar a partir del diagnóstico de densidades  

NASA Astrophysics Data System (ADS)

A partir de la observación del espectro del quintuplete de C III alrededor de 1175 Å, se ha realizado el diagnóstico de la densidad y presión electrónica, basado en el cálculo del cociente de las intensidades observadas. Una vez establecida la densidad electrónica, y con el cálculo de las velocidades Doppler, hemos investigado el flujo de masa en la protuberancia en función de la temperatura. Estableciendo como hipótesis la conservación del número de partículas que ingresan y salen del cuerpo de la protuberancia, se investiga la variación del área de un tubo de flujo semi-empírico en función de la temperatura. A partir de dicho diagnóstico, se examina el comportamiento del radio del tubo magnético en función de la temperatura, los que dan cuenta de la abertura de las líneas de campo magnético que confinan el plasma y de la divergencia del campo magnético en diferentes alturas de la atmósfera solar.

Cirigliano, D.; Vial, J. C.; Rovira, M.

436

Peat soil flows in Bahía del Buen Suceso, Tierra del Fuego (Argentina)  

NASA Astrophysics Data System (ADS)

On the southeastern edge of Tierra del Fuego, a mountainous area with a cold humid oceanic climate, peat soils cover not only flat areas but also steep hillslopes under an evergreen Nothofagus betuloides forest. Peat flows in the form of chutes are very frequent on these hillslopes. Some data were gathered on the field for 11 of these movements and from aerial photographs for 21 of them. The results suggest that peat soils become unstable when thickness exceeds a critical value which depends on the slope. This critical slope depends on the altitude and aspect regardless of soil thickness. A temporal analysis carried out by tree-ring counting demonstrated that the occurrence of these movements is not random though there are some periods of higher hazard, the probable triggering mechanisms being heavy snowfalls or earthquakes.

Gallart, Francesc; Clotet-Perarnau, Núria; Bianciotto, Oscar; Puigdefàbregas, Joan

1994-05-01

437

Análisis del espectro infrarrojo del polvo interestelar asociado con cúmulos globulares y de su evolución temporal  

NASA Astrophysics Data System (ADS)

El trabajo que se presenta investiga la dinámica de las partículas de polvo interestelar eyectadas por estrellas gigantes rojas en un cúmulo globular utilizando simulaciones numéricas de su interacción con el campo gravitatorio y con la radiación electromagnética de las estrellas. Se pretende con ello determinar la distribución espacial de ese material como una función del tiempo en un sistema similar a NGC 104 (47 Tuc). A partir de la distribución espacial resultante se obtuvo el espectro infrarrojo integrado el cual sugiere que el máximo contraste con la radiación estelar ocurre en longitudes de onda cercanas a 300 ?m y que decrece rápidamente hacia longitudes de onda menores, en las que suelen realizarse las observaciones.

Pellizza, L. J.; Forte, J. C.; Carpintero, D.

438

El diseño final del espectrógrafo de banco (EBASIM) para CASLEO  

NASA Astrophysics Data System (ADS)

Utilizando el código de óptica ACCOS V se ha finalizado el diseño del espectrógrafo de banco para CASLEO. En una comunicación anterior habíamos indicado que utilizaríamos un colimador de 150 mm de diámetro con un radio de curvatura de 1540 mm. Para el espejo cámara, que tiene un diámetro de 200 mm, el radio de curvatura es de 1200 mm, ambos radios con una tolerancia no mayor a los 3 mm. En la presente, se informa sobre los detalles finales del cálculo del espectrógrafo que incluye el cómputo para 5 longitudes de onda diferentes y alrededor de 100 rayos. En todos los casos el 75 % de energía está dentro de un diámetro de 13 micrones. El diseño ha sido probado entre 3500 Å hasta 9000 Å con resultados satisfactorios.

Simmons, J.; Levato, H.

439

EFECTO GENOTÓxICO DEL DICROMATO DE POTASIO EN ERITROCITOS DE SANGRE PERIFéRICA DE Oreochromis niloticus (TILAPIA)  

Microsoft Academic Search

RESUMEN Existen múltiples reportes del efecto genotóxico y cancerígeno del cromo VI, los seres humanos tenemos una permanente exposición a este elemento. Objetivos. Evidencias la genotoxicidad del dicromato de potasio utilizando como sistema biológico a Oreochromis niloticus \\

Zulita Prieto; Julio León-Incio; Carlos Quijano-Jara; Radigud Fernández; Edgardo Polo-Benites; Roger Vallejo-Rodríguez; Luis Villegas-Sanchez

440

Field measurements of del13C in ecosystem respiration  

NASA Astrophysics Data System (ADS)

Stable carbon isotope del13C-measurements are extensively used to study ecological and biogeochemical processes in ecosystems. Above terrestrial ecosystems, atmospheric del13C can vary largely due to photosynthetic fractionation. Photosynthetic processes prefer the uptake of the lighter isotope 12C (in CO2), thereby enriching the atmosphere in 13C and depleting the ecosystem carbon. At night, when ecosystem respiratory fluxes are dominant, 13C-depleted CO2 is respired and thereby depletes the atmospheric del13C-content. Different ecosystems and different parts of one ecosystem (type of plant, leaves, and roots) fractionate and respire with a different del13C-ratio signature. By determining the del13C-signature of ecosystem respiration in temporal and spatial scale, an analysis can be made of the composition of respiratory sources of the ecosystem. A field study at a dry cropland after harvest (province of Viterbo, Lazio, Italy) was performed in the summer of 2013. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure CO2-, CH4-, N2O-, CO- and del13C-concentrations. The FTIR was connected to 2 different flux measurements systems: a Flux Gradient system (sampling every half hour at 1.3m and 4.2m) and 2 flux chambers (measured every hour), providing a continuous data set of the biosphere-atmosphere gas fluxes and of the gas concentrations at different heights. Keeling plot intercept values of respiratory CO2, measured by the Flux Gradient system at night, were determined to be between -25‰ and -20‰. Keeling plot intercept values of respiratory CO2, measured by the flux chamber system, varied between -24‰ and -29‰, and showed a clear diurnal pattern, suggesting different (dominant) respiratory processes between day and night.

van Asperen, Hella; Sabbatini, Simone; Nicolini, Giacomo; Warneke, Thorsten; Papale, Dario; Notholt, Justus

2014-05-01

441

El doctor Varmus dirigirá una institución "inigualable", afirma el director del NCI, doctor John Niederhuber  

Cancer.gov

En un mensaje dirigido al personal del Instituto Nacional del Cáncer (NCI) y a quienes se interesan por la oncología, el doctor John Niederhuber, director del NCI, aplaude el nombramiento de Harold Varmus y afirma que esta designación le "dará al NCI un liderazgo fuerte no solo en la institución sino mas allá de ella, así como una voz muy respetada en el Congreso, que abogue por los recursos que son tan necesarios para sostener la misión del Instituto.

442

Net'aa chonaarãweda nepiripata p’edaa = Tradición oral del pueblo épera  

Microsoft Academic Search

La presencia épera en el Ecuador se remonta a principios de los años sesenta del siglo pasado, cuando pequeñas olas migratorias de indígenas colombianos del Saija llegaron a Ecuador y se asentaron en la región noroccidental de la provincia de Esmeraldas en la costa del Pacífico. Algunas razones para la migración fueron el comercio y la similitud entre su medio

J. Gómez Rendón; W. Poirama; L. Quiroz; B. Chiripua; Y. Capena

2008-01-01

443

Política monetaria y cambios de régimen en los tipos de interés del mercado interbancario español  

Microsoft Academic Search

En este trabajo analizamos el comportamiento dinámico del tipo de interés a un mes del mercado interbancario español entre 1987 y 2001. Se utiliza un proceso de difusión tipo raíz cuadrada que permite que el tipo cambie dependiendo del estado de la economía. El cambio entre regímenes es dirigido por un proceso de Markov de primer orden con probabilidades de

José Luis Fernández-Serrano; M. Dolores Robles Fernández

2004-01-01

444

Política Monetaria y Cambios de Régimen en los tipos de Interés del Mercado Interbancario  

Microsoft Academic Search

En este trabajo analizamos el comportamiento dinámico del tipo de interés a un mes del mercado interbancario español entre 1987 y 2001. Se utiliza un proceso de difusión tipo raíz cuadrada que permite que el tipo cambie dependiendo del estado en el que se encuentre la economía. El cambio entre regímenes es dirigido por un proceso de Markov de primer

José Luis Fernández Serrano; Dolores Robles Fernández

2002-01-01

445

Estudio Hidrológico del río Arlanzón a su paso por el Término Municipal de Burgos  

Microsoft Academic Search

Para la ordenación del territorio en el Término Municipal de Burgos se necesita conocer el riesgo de inundación por las aguas de los ríos Arlanzón, Vena, Cardeñadijo y Ubierna. Por ello, se ha realizado un estudio hidrológico de la cuenca del Arlanzón partiendo de los datos de precipitaciones, cartografía referente a usos del suelo, edafología, geología y topografía, fotografías aéreas

Iñigo OLEAGORDIA MONTAÑA; Rebeca RODRÍGUEZ GARCÍA; Joaquín NAVARRO HEVIA; CASTILLO NOVO

446

ESTUDIO MESOMECÁNICO DE LA FRACTURA DEL HORMIGÓN PARA DIFERENTES VELOCIDADES DE CARGA  

Microsoft Academic Search

Resumen. En este artículo se analiza el comportamiento del hormigón a un nivel mesomecánico de observación bajo cargas de tracción uniaxial dependientes del tiempo. Como punto de partida se ha empleado un modelo mesoestructural en 2D para materiales heterogéneos basado en elementos junta de espesor nulo, desarrollado dentro del grupo de investigación de la ETSECCPB-UPC. En este modelo, la estructura

Ricardo Lorefice; Guillermo Etse; Carlos M. López; Ignacio Carol

447

Interdisciplinary Unit: La Isla del Encanto (The Enchanted Island).  

ERIC Educational Resources Information Center

This document presents a series of 14 lesson plans in an interdisciplinary Spanish unit on "La isla del encanto/The Enchanted Island." The materials were prepared for students in grades 5 or 6 who have had basic Spanish instruction in previous grades. The students should also be familiar with basic concepts in English such as math computation, map…

Ford-Guerrera, Rebecca

448

Regulaciones del mercado laboral: un estudio comparativo entre países  

Microsoft Academic Search

En este trabajo se analizan tres tipos de instituciones prevalecientes en los mercados laborales de muchos países, normas sobre salario mínimo, introducción de costos no salariales (prestaciones complementarias) y las políticas de salario y empleo del gobierno. Se sostiene que estos tres son los aspectos estratégicos a analizar en el caso de los países en desarrollo con respecto a las

Peter R. Fallon; Luis Riveros

449

Estimación endógena del repudio en mercados soberanos de crédito  

Microsoft Academic Search

En vista de la falta de fundamentos teóricos en la bibliografía relacionada con el repudio en los mercados soberanos de crédito, se construye un modelo que considera todas las peculiaridades de los mercados internacionales de crédito. En particular, se incluye la idea de sanciones en el caso de repudio. Del modelo se extraen diversas conclusiones que contrastan con lo existente.

Fausto Hernández Trillo

1994-01-01

450

Del Mod: A State-Wide System for School Improvement.  

ERIC Educational Resources Information Center

This is a retrospective account of the Del Mod System, a statewide project to improve science and mathematics education in the elementary and secondary schools of Delaware. The project functioned from 1970-76 under the auspices of a committee including the presidents of institutions of higher education, the state superintendent of public…

Neale, Daniel C.

451

Advances in optical technologies at Pontificia Universidad Católica del Perú  

NASA Astrophysics Data System (ADS)

In this work, it is shown a panoramically view of advances and works on fundamental optical technology developed and Physics Section at Pontificia Universidad Católica del Perú PUCP in Lima Peru. This includes works in, precision optics manufacturing, optical testing, and optical design and simulation and also in optical thin film evaporation and its design techniques

Baldwin, Guillermo; Asmad, Miguel; Romero, Sandra; Gonzales, Franco; Gálvez, Gonzalo; Sánchez, Rubén; Córdova, Darwin

2011-05-01

452

Tratamiento del paludismo pediátrico: Papel de las intervenciones nutricionales  

Microsoft Academic Search

ResumenEl paludismo es una causa primordial de morbilidad y mortalidad en niños, particularmente en África subsahariana. Aunque se ha logrado un progreso considerable en el tratamiento del paludismo pediátrico con el tratamiento de combinación basado en la artemisinina, siguen existiendo numerosos obstáculos que se oponen a la puesta en práctica efectiva de estas nuevas opciones terapéuticas sumamente eficaces. Análogamente, si

Akoto Kwame Osei; Davidson H. Hamer

2008-01-01

453

Medical Ethnobotany of the Teribes of Bocas del Toro, Panama  

Microsoft Academic Search

Ethnomedical uses of 108 medicinal plant species, belonging to 52 families, 89 genera, used by the Teribe Amerindians of Bocas del Toro Province in Panama, along with their socio-cultural practices are reported here. The methods of administration of the herbal remedies, the plant parts used, their families and local names are also documented. The recorded medicinal plants were used mainly

M. P. Gupta; P. N. Solís; A. I. Calderón; F. Guinneau-Sinclair; M. Correa; C. Galdames; C. Guerra; A. Espinosa; G. I. Alvenda; G. Robles; R. Ocampo

2005-01-01

454

Aspetti evolutivi del sistema agro-alimentare in Algeria  

Microsoft Academic Search

Aspetti evolutivi del sistema agro-alimentare in Algeria (di Antonio Guariglia) - ABSTRACT: Even if it’s estimated that Algeria has potentially around 39 millions hectares of cultivable grounds, at present, the SAU is estimated equal to only 8 millions hectares (3% of territorial surface) situated in the almost totality along the fruitful and narrow coastal plan, while around 31 thousand hectares

Antonio Guariglia

2000-01-01

455

Regional geoid determination in Tierra del Fuego including GPS levelling  

Microsoft Academic Search

A regional geoid model for the Argentine part of the Isla Grande de Tierra del Fuego, established in previous works on the basis of GPS levelling, suffers a lack of observation data in the remote south-western investigation area. In order to improve the data distribution in this region, the mean lake level of Lago Fagnano has been regarded as a

Daniel del Cogliano; Reinhard Dietrich; Andreas Richter; Raúl Perdomo; José Luis Hormaechea; Gunter Liebsch; Mathias Fritsche

2007-01-01

456

Geological and Geophysical Investigations at Sierra del Medio Massif - Argentine.  

National Technical Information Service (NTIS)

Geological investigations were performed at Sierra del Medio (Chubut Province), a mountainous massif of about 25 km by 8 km of migmatic origin, which emerges from a depressed tectonic trench or graben called Pampa de Gastre. The most ancient rocks belong ...

J. C. Perucca E. Llambias H. H. Puigdomenech E. Cebrelli C. E. Castro

1987-01-01

457

The mercury clock of the Libros del Saber  

Microsoft Academic Search

The Libros del Saber de Astronomia is a compilation of various Arabic astronomical works translated into Castilian in the second half of the thirteenth century, under the direction of King Alfonso X of Spain. A section describing a mercury clock has been suggested to be of particular significance in view of the likely invention of the mechanical clock around this

A. A. Mills

1988-01-01

458

Políticas Española e Italiana según la Directiva Marco del Agua  

Microsoft Academic Search

RESUMEN Se ha elaborado un análisis de la evolución de la política internacional y europea, en relación a la gestión de los recursos hídricos, para identificar y comparar principios, objetivos y métodos de actuación en dos países mediterráneos miembros de la Unión Europea: Italia y España. La comparativa obtenida se hace tomando como referencia esencial la Directiva Marco del Agua,

Luis Miguel Valenzuela Montes; Anna Rigossi

2009-01-01

459

MATEMÁTICAS Y ORDENADORES EN EL CONOCIMIENTO DEL MUNDO  

Microsoft Academic Search

espacios abstractos, llamados hoy espacios de Hilbert, sería la base ,matemática de la ,Mecánica Cuántica. Esta situación contrasta con la del siglo XVII, en que Newton se vió obligado a desarrollar por sí mismo el cálculo diferencial para hacer convincentes las conclu- siones de los Principia, en tanto que a Hilbert le parecía que esfuerzos de este ,tipo ya no

M ANUEL L ÓPEZ; P ELLICER

460

L' IMPOLLINAZIONE DEL MIRTILLO GIGANTE AMERICANO (VACCINIUM CORYMBOSUM L.)  

Microsoft Academic Search

Nella fascia montana della nostra Regione la coltivazione delle specie frutticole minori è stata introdotta negli anni '80 come atti- vità agricola alternativa per diversificare le produzioni e come possibile integrazione al reddito per le aree marginali. Tra le diverse specie coltivate si annovera anche il mirtillo gigante (Vaccinium corymbosum L.). I fiori del mirtillo, di forma urceola- ta, sono

D. Prodorutti; F. Frilli; P. A. Belletti

461

Faculty Activity Analysis in the Universidad Tecnica Del Estado Campuses.  

ERIC Educational Resources Information Center

An analysis of academic activities of college faculty at the eight campuses of Chile's Universidad Tecnica del Estado was conducted. Activities were grouped into seven categories: direct teaching, indirect teaching, research, community services, faculty development, academic administration, and other activities. Following the narrative…

Karadima, Oscar

462

Se lanza Red Nacional de Estudios Clínicos del NCI  

Cancer.gov

El Instituto Nacional del Cáncer (NCI) puso en marcha una nueva red de investigación de estudios clínicos con el objetivo de mejorar el tratamiento de más de 1,6 millones de estadounidenses que reciben un diagnóstico de cáncer cada año.

463

Cosmogenic Radionuclides in the Campo Del Cielo Iron Meteorite  

NASA Technical Reports Server (NTRS)

Cosmogenic Be-10, Al-26, Cl-36, Ca-41, and Ni-59 were measured in the Campo del Cielo iron meteorite. Our results led us to conclude that the pre-atmospheric radius might have been approximately 2 m. Comparisons with other big bodies are also presented. Additional information is contained in the original extended abstract.

Liberman, R. G.; FernandezNiello, J. O.; Reedy, R. C.; Fifield, L. K.; diTada, M. L.

2001-01-01

464

Efecto del Programa de Entrenamiento "Manejo del Dolor" en la Documentaci?n de Enfermer?a en el Expediente Electr?nico  

PubMed Central

Resumen En el presente trabajo se muestra la importancia de entrenar al personal de enfermería para mejorar la documentación en el expediente electrónico. Se eligió el manejo del dolor por ser un área prioritaria; una alta proporción de pacientes en período post operatorio cursa con dolor, por lo tanto, la documentación debe ser útil para la toma de decisiones clínicas. Se implementó un programa de entrenamiento denominado “Manejo del Dolor” dirigido al personal de enfermería. Se utilizó la tecnología de la información como herramienta para fortalecer el conocimiento con base en la revisión sistemática de la literatura; el personal de enfermería participante seleccionó la mejor evidencia; posteriormente se trabajó en la transferencia de este conocimiento a la práctica a través del diseño de un protocolo para el manejo del dolor. Se concluye que el conocimiento del manejo del dolor es fundamental para que enfermería documente con mayor precisión sus intervenciones.

Monsivais, Maria Guadalupe Moreno; Guzman, Ma. Guadalupe Interial; Flores, Paz Francisco Sauceda; Arreola, Leticia Vazquez

2012-01-01

465

Molecular and cytogenetic characterization of del(9p) syndrome  

SciTech Connect

The del(9p) syndrome is characterized by mental retardation, trigonocephaly, midface hypoplasia, upward slanting palpebral fissures, a long philtrum, and is typically associated with a breakpoint at 9p22. Seventeen unrelated patients with del(9p) and their parents were analyzed by high resolution chromosome studies, molecular analysis using a series of highly polymorphic dinucleotide repeat markers for 9p, and fluorescence in situ hybridization (FISH) to characterize precisely the extent of chromosome loss. Eleven patients were found to have an interstitial deletion with breakpoints assigned to 9p22.1 and 9p24.3 in most cases. Two patients had familial unbalanced translocations of maternal origin and four had de novo complex rearrangements identified by high resolution analysis and FISH utilizing chromosome libraries. PCR analysis of eleven families with eight minisatellite markers determined paternal origin of the deletion in six cases and maternal origin in five. This suggests that the molecular event resulting in the deletion is equally prevalent in both male and female gametogenesis and that genomic imprinting does not play a role in the pathogenesis of del(9p) syndrome. Increased precision in mapping these minisatellite markers was also possible through this work. This study demonstrates the existence of molecular heterogeneity as six patients with a cytological breakpoint at 9p22.1 revealed three different molecular breakpoints. These findings suggest that genotype-phenotype correlations in deletion syndromes such as this should be based on high-resolution molecular analysis of the deleted chromosome segment. Work is in progress to map a series of cosmid probes by FISH relative to chromosomal breakpoints in these patients. These combined studies should provide a better understanding of the mechanisms involved in the pathogenesis of del(9p) syndrome and may identify loci where genes responsible for one or more aspects of the del(9p) phenotype may reside.

Micale, M.A.; Haren, J.M.; Schwartz, S. [Case Western Reserve Univ. School of Medicine, Cleveland, OH (United States)] [and others

1994-09-01

466

Moléculas orgánicas obtenidas en simulaciones experimentales del medio interestelar.  

NASA Astrophysics Data System (ADS)

Las nubes moleculares son regiones de formación de estrellas, con temperaturas cinéticas entre 10-50 K y densidades de 103-106 átomos cm-3. Su materia está formada por gas y polvo interestelar. Estas partículas de polvo están cubiertas por una fina capa de hielo, de unos 0.01 ?m, que contiene H2O y a menudo CO, CO2, CH3OH y NH3. El hielo es presumiblemente irradiado por fotones ultravioleta y rayos cósmicos en las zonas poco profundas de las nubes moleculares y las regiones circunestelares. En un sistema de vacío, P ˜ 10-7 mbar, simulamos la deposición de hielo a partir de 10 K y la irradiación ultravioleta por medio de una lámpara de descarga de hidrógeno activada con microondas. La evolución del hielo se observa por medio de un espectrómetro infrarrojo. De este modo es posible determinar la composición del hielo observado en el medio interestelar y predecir la presencia de moléculas aún no detectadas en el espacio, que han sido producto del procesamiento del hielo en nuestros experimentos. También es posible calentar el sistema hasta temperatura ambiente para sublimar el hielo depositado. Cuando el hielo ha sido previamente irradiado, se observa un residuo compuesto por moléculas orgánicas complejas, algunas prebióticas, como varios ácidos carboxílicos, aminas, amidas, ésteres y en menor proporción moléculas heterocíclicas y aminoácidos. Algunas de estas moléculas podrían detectarse en estado gaseoso por medio de observaciones milimétricas y de radio. También podrían estar presentes en el polvo cometario, cuyo análisis químico está planeado por las misiones Stardust y Rosetta. Mientras tanto, nuestro grupo está llevando a cabo el análisis de partículas de polvo interplanetario (IDPs), algunas de las cuales pueden ser de origen cometario. Al igual que ocurre con los productos obtenidos por irradiación del hielo en nuestros experimentos, algunas IDPs son ricas en material orgánico que contiene oxígeno.

Muñoz-Caro, Guillermo Manuel

467

LA CONSOLIDACIÓN DEL HAMBRE Y DEL DERECHO A LA ALIMENTACIÓN EN LAS AGENDAS POLÍTICAS DE AMÉRICA LATINA  

Microsoft Academic Search

América Latina y el Caribe es la única región en desarrollo que puede acabar con el hambre en nuestra generación. Tiene 52,4 millones de personas subnutridas (10% de población) y 9 millones de niños con desnutrición crónica, pero también es la principal productora mundial de alimentos y tiene recursos financieros, naturales, humanos e institucionales para hacer del hambre un recuerdo

Jose Luis Viveros; Niemeyer Almeida Filho

2008-01-01

468

La democracia constitucional en América Latina y las evoluciones recientes del presidencialismo. Memorias Encuentro del Instituto Iberoamericano de Derecho Constitucional  

Microsoft Academic Search

Siempre será oportuno reflexionar sobre la democracia, su contenido, sus desafíos, su presente y su futuro, las transformaciones y percepciones que de ella se tienen. No son pocas las preocupaciones o inquietudes que la democracia suscita en esta parte del mundo, y muestra de ello son los más variados estudios e informes sobre el estado actual de la democracia y

Pedro Pablo Vanegas

469

Prognostic Impact of del(17p) and del(22q) as Assessed by Interphase FISH in Sporadic Colorectal Carcinomas  

PubMed Central

Background Most sporadic colorectal cancer (sCRC) deaths are caused by metastatic dissemination of the primary tumor. New advances in genetic profiling of sCRC suggest that the primary tumor may contain a cell population with metastatic potential. Here we compare the cytogenetic profile of primary tumors from liver metastatic versus non-metastatic sCRC. Methodology/Principal Findings We prospectively analyzed the frequency of numerical/structural abnormalities of chromosomes 1, 7, 8, 13, 14, 17, 18, 20, and 22 by iFISH in 58 sCRC patients: thirty-one non-metastatic (54%) vs. 27 metastatic (46%) disease. From a total of 18 probes, significant differences emerged only for the 17p11.2 and 22q11.2 chromosomal regions. Patients with liver metastatic sCRC showed an increased frequency of del(17p11.2) (10% vs. 67%;p<.001) and del(22q11.2) (0% vs. 22%;p?=?.02) versusnon-metastatic cases. Multivariate analysis of prognostic factors for overall survival (OS) showed that the only clinical and cytogenetic parameters that had an independent adverse impact on patient outcome were the presence of del(17p) with a 17p11.2 breakpoint and del(22q11.2). Based on these two cytogenetic variables, patients were classified into three groups: low- (no adverse features), intermediate- (one adverse feature) and high-risk (two adverse features)- with significantly different OS rates at 5-years (p<.001): 92%, 53% and 0%, respectively. Conclusions/Significance Our results unravel the potential implication of del(17p11.2) in sCRC patients with liver metastasis as this cytogenetic alteration appears to be intrinsically related to an increased metastatic potential and a poor outcome, providing additional prognostic information to that associated with other cytogenetic alterations such as del(22q11.2). Additional prospective studies in larger series of patients would be required to confirm the clinical utility of the new prognostic markers identified.

Gonzalez-Gonzalez, Maria; Munoz-Bellvis, Luis; Mackintosh, Carlos; Fontanillo, Celia; Gutierrez, M. Laura; Abad, M. Mar; Bengoechea, Oscar; Teodosio, Cristina; Fonseca, Emilio; Fuentes, Manuel; De Las Rivas, Javier

2012-01-01

470

Fair trade, premio di prezzo e fallimenti del mercato  

Microsoft Academic Search

Il premio di prezzo è solo una componente, non marginale, sicuramente la più caratteristica e facilmente comunicabile, ma certamente non decisiva nel modello Fair Trade. L’avere incentrato l’attenzione su questo specifico aspetto del meccanismo complessivo ha nascosto altri aspetti più rilevanti dello schema operativo. Nel presente lavoro si cerca di mostrare come l’impatto maggiore delle strategie di Fair Trade riguarda

A. Arrighetti

2007-01-01

471

The Borexino detector at the Laboratori Nazionali del Gran Sasso  

Microsoft Academic Search

Borexino, a large volume detector for low energy neutrino spectroscopy, is currently running underground at the Laboratori Nazionali del Gran Sasso, Italy. The main goal of the experiment is the real-time measurement of sub-MeV solar neutrinos, and particularly of the monoenergetic (862keV) 7Be electron capture neutrinos, via neutrino–electron scattering in an ultra-pure liquid scintillator. This paper is mostly devoted to

G. Alimonti; C. Arpesella; H. Back; M. Balata; D. Bartolomei; A. de Bellefon; G. Bellini; J. Benziger; A. Bevilacqua; D. Bondi; S. Bonetti; A. Brigatti; B. Caccianiga; L. Cadonati; F. Calaprice; C. Carraro; G. Cecchet; R. Cereseto; A. Chavarria; M. Chen; A. Chepurnov; W. Czech; D. D’Angelo; F. Dalnoki-Veress; A. De Bari; E. De Haas; A. Derbin; M. Deutsch; A. Di Credico; A. Di Ludovico; G. Di Pietro; R. Eisenstein; F. Elisei; A. Etenko; F. von Feilitzsch; R. Fernholz; K. Fomenko; R. Ford; D. Franco; B. Freudiger; N. Gaertner; C. Galbiati; F. Gatti; S. Gazzana; V. Gehman; M. Giammarchi; D. Giugni; M. Goeger-Neff; T. Goldbrunner; A. Golubchikov; C. Grieb; C. Hagner; T. Hagner; W. Hampel; E. Harding; S. Hardy; F. X. Hartmann; R. von Hentig; T. Hertrich; G. Heusser; M. Hult; A. Ianni; An. Ianni; L. Ioannucci; K. Jaenner; M. Joyce; H. de Kerret; S. Kidner; J. Kiko; T. Kirsten; V. Kobychev; G. Korga; G. Korschinek; Yu. Kozlov; D. Kryn; P. La Marche; V. Lagomarsino; M. Laubenstein; C. Lendvai; M. Leung; T. Lewke; E. Litvinovich; B. Loer; F. Loeser; P. Lombardi; L. Ludhova; I. Machulin; S. Malvezzi; A. Manco; J. Maneira; W. Maneschg; I. Manno; D. Manuzio; G. Manuzio; M. Marchelli; A. Martemianov; F. Masetti; U. Mazzucato; K. McCarty; D. McKinsey; Q. Meindl; E. Meroni; L. Miramonti; M. Misiaszek; D. Montanari; M. E. Monzani; V. Muratova; P. Musico; H. Neder; A. Nelson; L. Niedermeier; S. Nisi; L. Oberauer; M. Obolensky; M. Obolensky; F. Ortica; M. Pallavicini; L. Papp; R. Parcells; S. Parmeggiano; M. Parodi; N. Pelliccia; L. Perasso; A. Pocar; R. Raghavan; G. Ranucci; W. Rau; A. Razeto; E. Resconi; P. Risso; A. Romani; D. Rountree; A. Sabelnikov; P. Saggese; R. Saldhana; C. Salvo; R. Scardaoni; D. Schimizzi; S. Schönert; K. H. Schubeck; T. Shutt; F. Siccardi; H. Simgen; M. Skorokhvatov; O. Smirnov; A. Sonnenschein; F. Soricelli; A. Sotnikov; S. Sukhotin; C. Sule; Y. Suvorov; V. Tarasenkov; R. Tartaglia; G. Testera; D. Vignaud; S. Vitale; R. B. Vogelaar; V. Vyrodov; B. Williams; M. Wojcik; R. Wordel; M. Wurm; O. Zaimidoroga; S. Zavatarelli; G. Zuzel

2009-01-01

472

Paradigmas de verbos en el zapoteco del istmo  

Microsoft Academic Search

Varios an?lisis se han hecho o pueden hacerse de las conjugaciones de los verbos en el zapoteco, una familia de lenguas de Oaxaca, M?xico. Marlett y Pickett 1987, siguiendo el an?lisis de Speck 1984, proponen uno para el zapoteco del istmo que hace referencia a un an?lisis de la estructura sil?bica de la lengua. Pickett 1967 presenta otro. Un desaf?o

Isthmus Zapotec; Verb Paradigms

473

3. 1939 DROP STRUCTURE IN DEL MAR PARK SURMOUNTED BY ...  

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

3. 1939 DROP STRUCTURE IN DEL MAR PARK SURMOUNTED BY RECENT PEDESTRIAN BRIDGE. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

474

2. COURSE OF THE LATERAL THROUGH DEL NORTHWEST MAR PARK. ...  

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

2. COURSE OF THE LATERAL THROUGH DEL NORTHWEST MAR PARK. - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

475

Solar adaptive optics at the Observatorio del Teide, Tenerife  

NASA Astrophysics Data System (ADS)

Observing the Sun with high angular resolution is difficult because the turbulence in the atmosphere is strongest during day time. In this paper we describe the principles of solar adaptive optics exemplified by the two German solar telescopes VTT and GREGOR at the Observatorio del Teide. With theses systems we obtain near diffraction limited images of the Sun. Ways to overcome the limits of conventional AO by applying multiconjugate adaptive optics (MCAO) are shown.

Soltau, Dirk; Berkefeld, Thomas; Schmidt, Dirk; von der Lühe, Oskar

2013-10-01

476

Nuevo sitio web en español del Instituto Nacional del Cáncer, (NCI, por sus siglas en inglés) Cancer.gov en español - Silvia Inéz Salazar - transcript  

Cancer.gov

Transmisiones de radio para promover Cancer.gov en espa%XF1ol | Nuevo sitio web en espa%XF1ol del Instituto Nacional del C%XE1ncer, (NCI, por sus siglas en ingl%XE9s) Cancer.gov en espa%XF1ol | Transcripci%XF3n Transmisiones de radio para promover

477

Un gobierno alternativo en una región olvidada de Colombia: entrevista al taita Floro Alberto Tunubalái Paja, gobernador del departamento del Cauca  

Microsoft Academic Search

El Departamento del Cauca está situado al Sur de Colombia. En los últimos años ha ocupado el penúltimo lugar en su aporte económico al país. Lós índices de pobreza son grandes, la oferta de trabajo es baja y la desatención y disminución del Estado se acentúa, haciendo cada vez más dificil la solución de las desigualdades sociales que vive la

Diego Jaramillo Salgado

2001-01-01

478

Correction: First high resolution ultraviolet (HST/STIS) and supporting optical spectroscopy of V339 Del = Nova Del 2013  

NASA Astrophysics Data System (ADS)

Due to an error in transcription, the distance is given incorrectly in the text of ATel#5409. Along with the typo "Space Telescope Imaging Spectrograph", the text should read: Comparing these STIS UV spectra with high resolution IUE spectra of the CO nova OS And 1986 obtained between 12 days (LWP) and 22 days (SWP) after optical discovery (1986 Dec. 17, 27 respectively) shows a very close agreement such that when independently dereddened, the ratio of V339 Del to OS And between 1200 and 1900A is ~1.5 in flux (similar in the 2000-3000A range but more uncertain because of the earlier date of the long wavelength IUE observation), indicating that the distance to V339 Del is about 4.2 kpc (distance to OS And ~ 5.1 kpc with E(B-V)=0.25+/-0.05, see Schwarz et al.

Shore, S. N.

2013-09-01

479

The 2012 Reactivation of Nevado del Ruiz Volcano, Colombia  

NASA Astrophysics Data System (ADS)

Nevado Del Ruiz volcano is most known for its tragic November 13, 1985 explosive event, when a small eruption produced an enormous lahar that buried and destroyed the town of Armero in Tolima, causing an estimated 25,000 deaths. Similar but less deadly incidents occurred in 1595 and 1845, again where a small explosive eruption was followed by a large lahar. Other minor explosive events occurred in 1805, 1828-9, and 1989. The Armero tragedy was a major factor in the establishment of a volcano monitoring program in Colombia. The network monitoring Nevado del Ruiz volcano has dramatically improved since the 1985 eruption and now includes geodetic, geophysical, geochemical and visual monitoring. The activity of Nevado Del Ruiz between 1985 and 1991 saw significant increases in seismicity and significant gas emissions with the main eruptive events of November 13, 1985 and September 1st, 1989. The volcano became seismically active again in 1995 and 2002, whit an increase in seismicity, without any gas emission or eruption. In October 2010 the volcano entered in a new phase of unrest with increased seismicity (HB events), deformation and gas emissions, likely associated with a new magma intrusion. In February, 2012 the volcano had a new and significant increase in seismicity (VT-LP), followed in May and June 2012 by small phreatic and phreato-magmatic eruption. This eruptive activity is still ongoing. Deformation measurements at Nevado Del Ruiz volcano have been carried out since just after the tragic eruption of the 13th of November 1985. In 2007 seven new electronic tilt meters were set up to monitor the deformation. Significant uplift was measured from August 2007 to October 2010, for a total cumulative value of more than 500 microradians. From the end of 2011 to July 2012, moderate changes of uplift were detected for a total of 70 microradians. The analysis of these deformation data shows a pattern of surface displacement associated with an intrusion of new magma coming from a reservoir located approximately at a depth of approximately 8 km and accumulating in shallow reservoir less than 2 km beneath the main crater. We fit the data with both a spherical and a vertical spheroid source. The spherical source indicates the existence of an intrusion at a depth of 1823±1056 m with a volume change of (7±17)×106 m3 . The vertical spheroidal source suggests a source 1855 m deep with a volume change of 6×106 m3 . These results imply that while we have strong bounds on the depth of the intrusion, the actual volume of the source is less certain. Gas emission from Nevado del Ruiz volcano in April 7, 2012.

Ordoñez, M.; Lopez, C.; Cortes, G. P.; Londoño, J.; Battaglia, M.

2012-12-01

480

Mutations in TP53 are exclusively associated with del(17p) in multiple myeloma  

PubMed Central

Deletion of the 17p13 chromosomal region [del(17p)] is associated with a poor outcome in multiple myeloma. Most of the studies have targeted the TP53 gene for deletion analyses, although no study showed that this gene is the deletion target. In order to address this issue, we sequenced the TP53 gene in 92 patients with multiple myeloma at diagnosis, 54 with a del(17p) and 38 lacking del(17p). At least one mutation was found in 20 patients, all of them presenting a del(17p). The analysis of the mutation location showed that virtually all of them occurred in highly conserved domains involved in the DNA-protein interactions. In conclusion, we showed that 37% of the myeloma patients with del(17p) present a TP53 mutation versus 0% in patients lacking the del(17p). The prognostic significance of these mutations remains to be evaluated.

Lode, Laurence; Eveillard, Marion; Trichet, Valerie; Soussi, Thierry; Wuilleme, Soraya; Richebourg, Steven; Magrangeas, Florence; Ifrah, Norbert; Campion, Loic; Traulle, Catherine; Guilhot, Francois; Caillot, Denis; Marit, Gerald; Mathiot, Claire; Facon, Thierry; Attal, Michel; Harousseau, Jean-Luc; Moreau, Philippe; Minvielle, Stephane; Avet-Loiseau, Herve

2010-01-01

481

VEGF: A modifier of the del22q11 (DiGeorge) syndrome?  

Microsoft Academic Search

Hemizygous deletion of chromosome 22q11 (del22q11) causes thymic, parathyroid, craniofacial and life-threatening cardiovascular birth defects in 1 in 4,000 infants. The del22q11 syndrome is likely caused by haploinsufficiency of TBX1, but its variable expressivity indicates the involvement of additional modifiers. Here, we report that absence of the Vegf164 isoform caused birth defects in mice, reminiscent of those found in del22q11

Ingeborg Stalmans; Diether Lambrechts; Frederik De smet; Sandra Jansen; Jian Wang; Sunit Maity; Paige Kneer; Maren von der Ohe; Ann Swillen; Christa Maes; Marc Gewillig; Daniel G. M. Molin; Peter Hellings; Thurid Boetel; Maartin Haardt; Veerle Compernolle; Mieke Dewerchin; Stephane Plaisance; Robert Vlietinck; Beverly Emanuel; Adriana C. Gittenberger-de Groot; Peter Scambler; Bernice Morrow; Deborah A. Driscol; Lieve Moons; Camila V. Esguerra; Geert Carmeliet; Annett Behn-Krappa; Koen Devriendt; Désiré Collen; Simon J. Conway; Peter Carmeliet

2003-01-01

482

Efectos derivados de la puesta en pr ctica del marketing de relaciones en los servicios profesionales  

Microsoft Academic Search

El objetivo del presente trabajo es identificar la influencia sobre el consumidor y sobre el resultado empresarial de dos dimensiones b sicas de los servicios profesionales: la dimensi¢n formal o calidad del servicio prestado y la dimensi¢n informal o interacci¢n personal con el cliente. Sobre la base te¢rica del marketing de relaciones, se analiza c¢mo influyen los aspectos formales e

Paolo Freire de Carvalho Filho; Carmen Camarero Izquierdo

2003-01-01

483

Use of Real Time PCR for Rapid Detection of Del Phenotype in Taiwan  

Microsoft Academic Search

During routine serologic procedures, Rh Del blood is often not identified and subsequently labeled as RhD-negative. Recently, several reports have shown the ability of Del blood to induce anti-D in RhD-negative recipients. Among Korean, Japanese, and Chinese, almost all individuals with Del blood have a nucleotide change in the RHD gene of 1227G>A (RHDK407K). Thus, nucleotide 1227A at RHD exon

Chien-Feng Sun; Jui-Ping Liu; Ding-Ping Chen; Wei-Ting Wang; Tyng-Tyng Yang

484

Els Fragments del Sacramentari de Sant Boi de Lluçanès (Vic. Bib. Espisc., Frag I\\/6)  

Microsoft Academic Search

Els disset folis del manuscrit Vic, Bib. Episc., frag. I\\/6 són les restes d'un sacramentari de tipus gregorià mixt, procedents de la parròquia de Sant Boi de Lluçanès. Foren escrites en l'últim quart del segle X, però, al segon quart del segle XII s'hi feren esmenes adaptant el seu cànon als models d'aquest segle. En això rau la seva singularitat.

Miquel dels Sants Gros i Pujol

2005-01-01

485

Stator Bar Vibration Sensors and Fiber-Optic Accelerometers New Tools Used to Measure Stator Winding Vibration in Large Turbine Generators  

Microsoft Academic Search

Vibration analysis has been conducted on large rotating machines for many decades. Proximity probes and accelerometers are traditionally used to measure bearing and shaft vibration in an effort to keep mechanical condition in check. Simple measurement of amplitude, to the more complex analysis such as Fast Fourier Transforms, are made by maintenance personnel in an effort to identify the source,

Mike Hoffer; Andrew Tesla

486

Distribución del continuo ultravioleta e infrarrojo en estrellas Be  

NASA Astrophysics Data System (ADS)

Estamos interesados en interpretar los excesos de flujo infrarrojo y/o ultravioleta observados en estrellas Be con respecto al de estrellas B normales, así como su posible correlación. Una envoltura rodeando la estrella distingue una estrella Be de una B normal; para explicar las observaciones es necesario entonces tener en cuenta todos los posibles procesos físicos que en ella tienen lugar. Adoptando un modelo atmosférico específico, hemos estudiado el proceso de recombinación dielectrónica de metales como MgII y FeII, teniendo en cuenta la posible influencia de la opacidad del medio en el flujo emitido.

Cruzado, A.; Ringuelet, A.; di Rocco, H.

487

Tireoidite auto-imune bociogenica. Aspectos do diagnostico clinico e laboratorial. (Autoimmune thyroiditis goitrogenic. Aspects of clinical and laboratorial diagnosis).  

National Technical Information Service (NTIS)

To asses the accuracy achieved by the A.C.A.T. and other clinical and laboratorial criterion in the diagnoses of T.A.I.B. we investigated twenty patients with goiter and antimicrossomal antibodies titres of 1/1.600 or more. Analysing the parameters useful...

H. F. Z. Costa

1986-01-01

488

Iter diagnostico nelle patologie asbesto correlate, considerazioni a margine di un caso clinico di sospetta neoplasia professionale  

Microsoft Academic Search

In our country the rate of asbestos - related neoplasia, in particular pleural mesothelioma and lung cancer, is increasing; the data provided by INAIL concerning the complaints for occupational diseases filed in 2006 ex table D.P.R. 336\\/1994 (neoplastic diseases caused by asbestos: pleural, pericardial and peritoneal mesothelioma; lung cancer) are significant. The total number of such complaints in our country

F. Spigno; R. Gentile; T. Valente; G. Capannelli

2008-01-01

489

Recoleccion de Muestras para Diagnostico de Enfermedades de los Animales (Collection and Delivery of Samples for Diagnosis of Animal Diseases).  

National Technical Information Service (NTIS)

The manual provides instructions for collecting and handling samples for diagnosis of 65 animal diseases. Livestock reviewed included sheep, beef cattle, horses, swine, dogs, poultry, alpacas. Also reviews analysis for parasites.

C. L. Ortecho M. Vasquez C. Marchinares

1967-01-01

490

Variabilidad del metabolismo oxidativo de fármacos en la población uruguaya Polimorfismo genético del citocromo P-450 2D6  

Microsoft Academic Search

Resumen El estudio ele losj¿7ctores gméticos que determirmr7 la respuesta a los 7~2edictr7i2erzfo.s se demmirm ,fi77.7rlacogerrética. EH la década del 70 se describió el polirnorfïsmo perr&ico dc Iri Llchri.coqLrina-hidroxiiasa. u77 hallazgo de gran r-elevatrcia dado que rnlrclîo.r.f¿í~\\/llcrc,o.c utili:ados cu terapéutica se oxidar? por la misma \\\\jía metahólic~a. Esto e.xpliccr ,grrrrr parte LIP iir var-iahilitiud iudividual que se obset-va en las

Francisco E. Estévez; Marcos Giusti; Susana Parrillo; Miguel Pr-ando

1997-01-01

491

Aparición del cometa Hale - BOPP C / 1995-01  

NASA Astrophysics Data System (ADS)

El Cometa Hale - Bopp fue observado a partir de la 10ma. magnitud con el telescopio de 300mm de abertura a f/6.5. En esas primeras observaciones desde luego no hubo mucho detalle. A su vez las posiciones del cometa para nuestro hemisferio no fueron favorables, solamente asomó por el horizonte N.O. para nuestra latitud cuando se alejaba de la Tierra. Se registró la observación visualmente con binoculares 10 x 50, y fotográficamente con un Telezoom de 210mm a f/4,5 con película 400 ASA color. Todas las imágenes fueron procesadas y digitalizadas a fin de obtener las diferentes escalas de brillo. El aspecto que presentó para nuestra posición geográfica fue discreta ya que tuvo su máximo brillo cuando era visible desde el hemisferio norte. Presentó la clásica cola de polvo curva, y con su aspecto casi estelar, destacándose entre la luminosidad del crepúsculo. Instrumentos Utilizados: Telezoom de 210mm a f/4.5, Telescopio refractor de 80mm a f/15, Binocular 10 x 50

Arquiola, A.

492

Deadly Lahars from Nevado del Ruiz, Colombia: November 13, 1985  

NSDL National Science Digital Library

This web site describes a series of Lahars that occurred from the Nevado del Ruiz volcano in the Andes mountains, the northernmost and highest volcano in Colombia. Beginning in November 1984, the volcano began showing clear signs of unrest. An explosive eruption from Ruiz's summit crater on November 13, 1985, at 9:08 p.m. generated an eruption column and sent a series of pyroclastic flows and surges across the volcano's summit. Within minutes, pumice and ash began to fall to the northeast along with heavy rain that had started earlier in the day. Within four hours, lahars had traveled 100 km and left behind a wake of destruction: more than 23,000 people killed, about 5,000 injured, and more than 5,000 homes destroyed along the Chinchina, Guali, and Lagunillas rivers and destroying the town of Armero, Columbia. This deadly eruption of Nevado del Ruiz offers lessons on the generation of lahars for scientists, emergency-response professionals, and communities located downstream of such ice- and snow-covered volcanoes. The narrative is illustrated with 9 photographs.

Banks, N.; Marso, J.; Pierson, T.; Janda, R.

493

Descubrimiento del primer yacimiento cuaternario (Riss-Wiirm) de vertebrados con restos humanos en la provincia de Madrid (Pinilla del Valle)  

Microsoft Academic Search

We give notice of a new fossiliferous loeality with vertebrate rests of Pleistocene age, placed in Pinilla del Valle (Madrid). It is made up by quaternary sediments filling a ca)careous fallen shelter.

E. ALFÉREZ; G. MOLERO; E. MALDONADO; P. BREA; A. IV

494

Targeting F508del-CFTR to develop rational new therapies for cystic fibrosis  

Microsoft Academic Search

The mutation F508del is the commonest cause of the genetic disease cystic fibrosis (CF). CF disrupts the function of many organs in the body, most notably the lungs, by perturbing salt and water transport across epithelial surfaces. F508del causes harm in two principal ways. First, the mutation prevents delivery of the cystic fibrosis transmembrane conductance regulator (CFTR) to its correct

Zhi-wei Cai; Jia Liu; Hong-yu Li; David N Sheppard

2011-01-01

495

Violación del Principio de Equivalencia en Teorías con Dilatón de Cuerdas  

Microsoft Academic Search

Se estudian las violaciones al Principio de Equivalencia en Teorías con Dilatón de Cuerdas. En estos modelos, algunas de las constantes fundamentales dependen del espacio y del tiempo. Se muestra que los experimentos de caída libre no tienen aún precisión como para poner límites a los parámetros de la teoría.

S. J. Landau; P. D. Sisterna; H. Vucetich

2003-01-01

496