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1

Filament-induced laser machining (FILM)  

NASA Astrophysics Data System (ADS)

Laser filamentation provides high intensity plasma strings of micrometric diameters and lengths of tens of centimeters. We demonstrate that these filaments can be used for remotely drilling and cutting metals and biological materials such as flesh and bones. Since no tight focusing is needed, complex 3D shapes can be machined without any adjustment of the laser while processing.

Kiselev, D.; Woeste, L.; Wolf, J.-P.

2010-09-01

2

Filament-induced laser machining (FILM)  

Microsoft Academic Search

Laser filamentation provides high intensity plasma strings of micrometric diameters and lengths of tens of centimeters. We\\u000a demonstrate that these filaments can be used for remotely drilling and cutting metals and biological materials such as flesh\\u000a and bones. Since no tight focusing is needed, complex 3D shapes can be machined without any adjustment of the laser while\\u000a processing.

D. Kiselev; L. Woeste; J.-P. Wolf

2010-01-01

3

Filament-Winding Technique for Concave Parts  

NASA Technical Reports Server (NTRS)

Dummy mold and vacuum bagging yield accurate part girth. Proposed method of filament winding facilitates accurate fabrication of fiber/matrix composite parts having closed sections with concave surfaces. Parts laid up by hand now wound with filaments; reducing time and cost of fabrication and improving quality of parts.

Carter, Donald; Schmaling, David

1987-01-01

4

Screening of epoxy systems for high performance filament winding applications  

NASA Technical Reports Server (NTRS)

Several promising epoxy systems for high performance filament winding applications are described. Viscosities, gel times, and cast resin tensile behavior are given, as well as heat deflection under load and water absorption measurements.

Chiao, T. T.; Jessop, E. S.; Penn, L.

1975-01-01

5

Optimum windings for linear induction machines.  

NASA Technical Reports Server (NTRS)

The matrix method of calculating linear induction machine performance as a function of winding current distribution was extended to determine the winding current distribution for maximum efficiency. Application of the method to typical magnetohydrodynamic generator geometries showed that electrical efficiencies of 0.5 to 0.6 are possible with fractional wavelength windings and without insulating vanes in the flow.

Elliott, D. G.

1973-01-01

6

Composite Pressure Vessel Variability in Geometry and Filament Winding Model  

NASA Technical Reports Server (NTRS)

Composite pressure vessels (CPVs) are used in a variety of applications ranging from carbon dioxide canisters for paintball guns to life support and pressurant storage on the International Space Station. With widespread use, it is important to be able to evaluate the effect of variability on structural performance. Data analysis was completed on CPVs to determine the amount of variation that occurs among the same type of CPV, and a filament winding routine was developed to facilitate study of the effect of manufacturing variation on structural response.

Green, Steven J.; Greene, Nathanael J.

2012-01-01

7

STARBURST-DRIVEN GALACTIC WINDS: FILAMENT FORMATION AND EMISSION PROCESSES  

SciTech Connect

We have performed a series of three-dimensional simulations of the interaction of a supersonic wind with a nonspherical radiative cloud. These simulations are motivated by our recent three-dimensional model of a starburst-driven galactic wind interacting with an inhomogeneous disk, which shows that an optically emitting filament can be formed by the breakup and acceleration of a cloud into a supersonic wind. In this study, we consider the evolution of a cloud with two different geometries (fractal and spherical) and investigate the importance of radiative cooling on the cloud's survival. We have also undertaken a comprehensive resolution study in order to ascertain the effect of the assumed numerical resolution on the results. We find that the ability of the cloud to radiate heat is crucial for its survival, with a radiative cloud experiencing a lower degree of acceleration and having a higher relative Mach number to the flow than in the adiabatic case. This diminishes the destructive effect of the Kelvin-Helmholtz instability on the cloud. While an adiabatic cloud is destroyed over a short period of time, a radiative cloud is broken up via the Kelvin-Helmholtz instability into numerous small, dense cloudlets, which are drawn into the flow to form a filamentary structure. The degree of fragmentation is highly dependent on the resolution of the simulation, with the number of cloudlets formed increasing as the Kelvin-Helmholtz instability is better resolved. Nevertheless, there is a clear qualitative trend, with the filamentary structure still persistent at high resolution. The geometry of the cloud affects the speed at which the cloud fragments; a wind more rapidly breaks up the cloud in regions of least density. A cloud with a more inhomogeneous density distribution fragments faster than a cloud with a more uniform structure (e.g., a sphere). We confirm the mechanism behind the formation of the Halpha emitting filaments found in our global simulations of a starburst-driven wind. Based on our resolution study, we conclude that bow shocks around accelerated gas clouds, and their interaction, are the main source of the soft X-ray emission observed in these galactic-scale winds.

Cooper, Jackie L.; Bicknell, Geoffrey V.; Sutherland, Ralph S. [Research School of Astronomy and Astrophysics, Australian National University, Canberra ACT 0200 (Australia); Bland-Hawthorn, Joss, E-mail: jcooper@mso.anu.edu.a [Institute of Astronomy, School of Physics, University of Sydney, NSW 2006 (Australia)

2009-09-20

8

Multi-winding homopolar electric machine  

DOEpatents

A multi-winding homopolar electric machine and method for converting between mechanical energy and electrical energy. The electric machine includes a shaft defining an axis of rotation, first and second magnets, a shielding portion, and a conductor. First and second magnets are coaxial with the shaft and include a charged pole surface and an oppositely charged pole surface, the charged pole surfaces facing one another to form a repulsive field therebetween. The shield portion extends between the magnets to confine at least a portion of the repulsive field to between the first and second magnets. The conductor extends between first and second end contacts and is toroidally coiled about the first and second magnets and the shield portion to develop a voltage across the first and second end contacts in response to rotation of the electric machine about the axis of rotation.

Van Neste, Charles W

2012-10-16

9

Analysis of filament wound composite structures considering the change of winding angles through the thickness direction  

Microsoft Academic Search

In this study, filament winding patterns were calculated using a semi-geodesic fiber path equation for an arbitrary surface. Because the fiber path depends on the surface where fibers are wound, the winding angle varies in the longitudinal and thickness directions of a wound structure. The fiber angle difference through the thickness was calculated for several design parameters, such as helical

Jae-Sung Park; Chang-Sun Hong; Chun-Gon Kim; Cheol-Ung Kim

2002-01-01

10

Electrical machine having controlled characteristics and its application to a wind-driven machine  

SciTech Connect

The invention provides an electrical machine having an inductor and an armature, one of which has at least two independent winding assemblies. The switching into and out of circuit of each winding assembly is controlled by a processor which receives monitoring parameters of the machine and desired value parameters, thereby controlling in real time the operating characteristics of the machine. The machine may be a winddriven generator.

Berna, M.; Kant, M.; Seger, R.; Vilain, J.P.

1983-07-26

11

Analytical calculation model for stator winding faults in synchronous machines  

Microsoft Academic Search

The calculation of currents and torques after inner faults in the stator of synchronous machines requires accurate models considering the inner asymmetry of the winding. The paper introduces a mathematical network model of a synchronous machine with arbitrary short circuited windings, which is generally open for the consideration of nonlinear iron. The system of equations is derived using an example

Jens Rosendahl; Hendrik Steins

2010-01-01

12

Numerical field calculation of stator winding faults in synchronous machines  

Microsoft Academic Search

Purpose – The purpose of this paper is to describe a systematic investigation of the currents, torques and other electromagnetic quantities in a machine after different short circuits by the means of coupled numerical field and network calculation. The behaviour of a synchronous machine after a stator-winding fault still is a little known issue. Nevertheless, the occurrence of winding faults

Jens Rosendahl; Stefan Kulig

2009-01-01

13

Fields of Opportunity: Wind Machines Return to the Plains  

ERIC Educational Resources Information Center

The last two decades have seen a rebirth of wind machines on the rural landscape. In ironic fashion the wind's kinetic energy has grown in significance through its ability to generate commercial amounts of electricity, the commodity that a few generations earlier hastened the demise of the old Great Plains windmill. Yet the reemergence of wind

Sowers, Jacob

2006-01-01

14

Modeling induction machine winding faults for diagnosis In Electrical Machines Diagnosis  

E-print Network

Chapter 2 Modeling induction machine winding faults for diagnosis In Electrical Machines Diagnosis the fault appears, its diagnosis (detection, location, characterization of fault severity) and the decision of a winding fault situation, then the time available to the experimenter may vary from a few minutes to a few

Paris-Sud XI, Université de

15

High pressure gas storage capacities. Example of a solution using filament windings  

NASA Technical Reports Server (NTRS)

The use of epoxy resin fiber glass and economic factors affecting the choice of materials for gas storage are discussed. The physical nature of the filament windings are described together with the results obtained. It is demonstrated that a substantial reduction in mass and an enhanced level of safety can be assured at a competitive cost by storing gases in this way.

Phan, A.; Lamalle, J.

1981-01-01

16

Simulation of a computational winding filament model with an exponential spring to represent titin.  

PubMed

The goal of developing high fidelity simulation of muscle force is of considerable interest for the biomedical community. Traditionally Hill models have been incorporated. However, feasible scope of the Hill model is inherently limited, especially in light of the growing relevance of muscle history dependence. History dependence is considered to be significant for motor control and stability. Attempts have been made to augment the Hill model to emulate history dependence. The titin winding filament model best elucidates history dependence of muscle force including force enhancement. The recent version of the titin winding filament model accounts for the functionality of titin through a pulley linked with the contractile element and a linear spring to represent the elastic properties of titin. A new and more realistic amendment to the winding filament model is incorporation of an exponential spring to characterize the elastic properties of titin. A sensitivity study as a function of the titin exponential spring constant is presented. Overall the amalgamation of the titin exponential spring to the winding filament model improves the respective force enhancement characteristics with a relatively more optimal exponential spring constant that provides a maximal averaged coefficient of determination. PMID:25570089

LeMoyne, Robert; Petak, Jeremy; Tester, John; Nishikawa, Kiisa

2014-08-01

17

DEVELOPMENT of CEMENT BASED CROSS-PLY LAMINATES by FILAMENT WINDING TECHNIQUE  

E-print Network

strain increase considerably [2]. Work of Stang and Krenchel [3] showed that by using a high volume. Mobasher2 ABSTRACT A filament winding system was developed for manufacturing cross ply composites using continuous fibers. The computer controlled system is used for manufacturing composite laminates, pipes

Mobasher, Barzin

18

Filament winding technique produces strong lightweight oxygen tanks  

NASA Technical Reports Server (NTRS)

Fiberglass is wound in three winding and cure sequences with first two followed by grit blasting of surface before final step. Result is uniformly stressed metal liner assembly with excellent structural characteristics.

Shuessler, J. F.; Dannenmueller, R. J.

1973-01-01

19

Liquid oxygen-compatible filament-winding matrix resin  

NASA Technical Reports Server (NTRS)

Polyurethanes derived from hydroxy terminated polyperfluoro propylene oxide prepolymers were evaluated as matrix resins for filament wound composites which would be exposed to liquid (and 100% gaseous) oxygen environments. A number of structural modifications were brought about by variations in prepolymer molecular weight, and alternative curing agents which allowed retention of the oxygen compatibility. Although satisfactory performance was achieved at sub-ambient temperatures, the derived composites suffered considerable property loss at ambient or slightly elevated temperatures. To attain overall effectiveness of the composite system, upgrading of the polymer thermomechanical properties must first be achieved.

Harrison, E. S.

1973-01-01

20

Permanent magnet machine with windings having strand transposition  

DOEpatents

This document discusses, among other things, a stator with transposition between the windings or coils. The coils are free from transposition to increase the fill factor of the stator slots. The transposition at the end connections between an inner coil and an outer coil provide transposition to reduce circulating current loss. The increased fill factor reduces further current losses. Such a stator is used in a dual rotor, permanent magnet machine, for example, in a compressor pump, wind turbine gearbox, wind turbine rotor.

Qu, Ronghai (Clifton Park, NY); Jansen, Patrick Lee (Scotia, NY)

2009-04-21

21

Filament Winding of Co-Extruded Polypropylene Tapes for Fully Recyclable All-Polypropylene Composite Products  

Microsoft Academic Search

The creation of high-strength co-extruded polypropylene (PP) tapes allows the production of recyclable “all-polypropylene”\\u000a (all-PP) composite products, with a large temperature processing window and a high fibre volume fraction. Available technologies\\u000a for all-PP composites are mostly based on manufacturing processes such as thermoforming of pre-consolidated sheets. The objective\\u000a of this research is to assess the potential of filament winding as

N. O. Cabrera; B. Alcock; E. T. J. Klompen; T. Peijs

2008-01-01

22

Inrush Current Simulation of Two Windings Power Transformer using Machine Parameters Estimated by Design Procedure of Winding Structure  

NASA Astrophysics Data System (ADS)

This paper presents estimation techniques of machine parameters for two windings power transformer using design procedure of winding structure. Especially, it is very difficult to obtain machine parameters for transformers in customers' facilities. Using estimation techniques, machine parameters could be calculated from the only nameplate data of these transformers. Subsequently, EMTP-ATP simulation of the inrush current was carried out using machine parameters estimated by design procedure of winding structure and simulation results were reproduced measured waveforms.

Tokunaga, Yoshitaka; Kubota, Kunihiro

23

WindTech TV: Bonus Materials- Machine Control Circuits  

NSDL National Science Digital Library

This section of the Wind Technician TV website provides bonus materials pertaining to machine control circuits. Users can review content on topics like electrical theory, magnetics, ladder diagrams and start-stop interlock example. Clicking on a subtopic will launch a pop up window demonstrating the concept.

2013-07-01

24

Finite element calculation of harmonic losses in AC machine windings  

Microsoft Academic Search

The finite-element method (FEM) with circuit constraints is used to study the problem of harmonic losses in stranded conductors typically found in AC machines. A discussion of the method is given along with examples using actual motor windings. The results of the finite element calculations are compared to a closed-form solution which ignores the effects of eddy currents on the

S. J. Salon; L. Ovacik; J. F. Balley

1993-01-01

25

Terrain and Ambient Wind Effects on the Warming Footprint of a Wind Machine  

SciTech Connect

An experiment in a vineyard in south-central Washington is described in which a vineyard wind machine used for frost protection was turned on and off while monitoring the air temperature in the vineyard. The wind machine fan, with a hub height of 12 m, rotated around a quasi-horizontal axis that was tilted downward into the vineyard at an angle of 6 degrees. The fan also rotated around a vertical axis once every 4 minutes to protect a roughly circular area surrounding the wind machine tower. A temperature inversion of about 3.5 C occurred above the vineyard between the 3-m and hub-height levels during the experiments. The 300-m diameter warming footprint of the fan was displaced down the south-facing 1-2{sup o} slope of the vineyard when the ambient wind speed was low, showing the effect of the weak and shallow nighttime drainage flow that often occurred in the vineyard. When the ambient wind speed increased, the footprint was displaced downwind and downslope of the tower. The mean warming footprint magnitude when the fan was switched on was about 1-2 C, and the temperature excess in the footprint relative to the surroundings dissipated quickly when the fan was switched off.

Mcmeeking, Gavin R.; Whiteman, Charles D.; Powell, Stuart G.; Clements, Craig B.

2002-05-20

26

Measurement of large AC electrical machine stator windings parameters at high frequency  

Microsoft Academic Search

To analyze the propagation of high frequency signals, such as partial discharge, dv\\/dt, di\\/dt of PWM inverters in electric machines, it is necessary to determine the stator windings parameters at high frequency. This paper describes an experimental method for measuring the stator windings parameters of AC large electrical machine at high frequency. The method is based on the theory of

Z. L. Xian; J. G. Jiang; L. H. He; D. H. Liu; H. X. Cao

2003-01-01

27

Winding Inductances of Fractional Slot Surface-Mounted Permanent Magnet Brushless Machines  

Microsoft Academic Search

Permanent magnet (PM) brushless machines equipped with fractional-slot concentrated-windings (FSCW) have been receiving considerable attention over the past few years, due to the fact that they have short end-windings, a high slot fill factor, a high efficiency and power density, and good flux- weakening and fault-tolerance capabilities. A key design parameter for such machines is the phase winding inductance since

Ayman M. EL-Refaie; Z. Q. Zhu; T. M. Jahns; D. Howe

2008-01-01

28

Pole-phase modulated toroidal winding for an induction machine  

DOEpatents

A stator (10) for an induction machine for a vehicle has a cylindrical core (12) with inner and outer slots (26, 28) extending longitudinally along the inner and outer peripheries between the end faces (22, 24). Each outer slot is associated with several adjacent inner slots. A plurality of toroidal coils (14) are wound about the core and laid in the inner and outer slots. Each coil occupies a single inner slot and is laid in the associated outer slot thereby minimizing the distance the coil extends from the end faces and minimizing the length of the induction machine. The toroidal coils are configured for an arbitrary pole phase modulation wherein the coils are configured with variable numbers of phases and poles for providing maximum torque for cranking and switchable to a another phase and pole configuration for alternator operation. An adaptor ring (36) circumferentially positioned about the stator improves mechanical strength, and provides a coolant channel manifold (34) for removing heat produced in stator windings during operation.

Miller, John Michael (Saline, MI); Ostovic, Vlado (Weinheim, DE)

1999-11-02

29

Mars vertical axis wind machines: The design of a tornado vortex machine for use on Mars  

NASA Astrophysics Data System (ADS)

Ever since Viking 1 and 2 landed on the surface of Mars in the summer of 1976, man has yearned to go back. But before man steps foot upon the surface of Mars, unmanned missions such as the Martian Soft Lander and Martian Subsurface Penetrator will precede him. Alternative renewable power sources must be developed to supply the next generation of surface exploratory spacecraft, since RTG's, solar cells, and long-life batteries all have their significant drawbacks. One such alternative is to take advantage of the unique Martian atmospheric conditions by designing a small scale, Martian wind power generator, capable of surviving impact and fulfilling the long term (2-5 years), low-level power requirements (1-2 Watts) of an unmanned surface probe. After investigation of several wind machines, a tornado vortex generator was chosen based upon its capability of theoretically augmenting and increasing the available power that may be extracted from average Martian wind speeds of approximately 7.5 m/s. The Martian Tornado Vortex Wind Generator stands 1 meter high and has a diameter of 0.5 m. Martian winds enter the base and shroud of the Tornado Vortex Generator at 7.5 m/s and are increased to an exit velocity of 13.657 m/s due to the vortex that is created. This results in a rapid pressure drop of 4.56 kg/s(exp 2) m across the vortex core which aids in producing a net power output of 1.1765 Watts. The report contains the necessary analysis and requirements needed to feasibly operate a low-level powered, unmanned, Martian surface probe.

Carlin, Daun; Dyhr, Amy; Kelly, Jon; Schmirler, J. Eric; Carlin, Mike; Hong, Won E.; Mahoney, Kamin; Ralston, Michael

1994-06-01

30

Mars vertical axis wind machines: The design of a tornado vortex machine for use on Mars  

NASA Technical Reports Server (NTRS)

Ever since Viking 1 and 2 landed on the surface of Mars in the summer of 1976, man has yearned to go back. But before man steps foot upon the surface of Mars, unmanned missions such as the Martian Soft Lander and Martian Subsurface Penetrator will precede him. Alternative renewable power sources must be developed to supply the next generation of surface exploratory spacecraft, since RTG's, solar cells, and long-life batteries all have their significant drawbacks. One such alternative is to take advantage of the unique Martian atmospheric conditions by designing a small scale, Martian wind power generator, capable of surviving impact and fulfilling the long term (2-5 years), low-level power requirements (1-2 Watts) of an unmanned surface probe. After investigation of several wind machines, a tornado vortex generator was chosen based upon its capability of theoretically augmenting and increasing the available power that may be extracted from average Martian wind speeds of approximately 7.5 m/s. The Martian Tornado Vortex Wind Generator stands 1 meter high and has a diameter of 0.5 m. Martian winds enter the base and shroud of the Tornado Vortex Generator at 7.5 m/s and are increased to an exit velocity of 13.657 m/s due to the vortex that is created. This results in a rapid pressure drop of 4.56 kg/s(exp 2) m across the vortex core which aids in producing a net power output of 1.1765 Watts. The report contains the necessary analysis and requirements needed to feasibly operate a low-level powered, unmanned, Martian surface probe.

Carlin, Daun; Dyhr, Amy; Kelly, Jon; Schmirler, J. Eric; Carlin, Mike; Hong, Won E.; Mahoney, Kamin

1994-01-01

31

Broken Bar Detection in Synchronous Machines Based Wind Energy Conversion System  

E-print Network

BROKEN BAR DETECTION IN SYNCHRONOUS MACHINES BASED WIND ENERGY CONVERSION SYSTEM A Dissertation by MINA MASHHADI RAHIMIAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment... of the requirements for the degree of DOCTOR OF PHILOSOPHY August 2011 Major Subject: Electrical Engineering BROKEN BAR DETECTION IN SYNCHRONOUS MACHINES BASED WIND ENERGY CONVERSION SYSTEM A Dissertation by MINA MASHHADI RAHIMIAN...

Rahimian, Mina Mashhadi

2012-10-19

32

Coil connections and winding factors in flux-switching PM brushless AC machines  

Microsoft Academic Search

Purpose – The purpose of this paper is to analyze the phase coil connections and winding factors of flux-switching permanent magnet (FSPM) brushless AC machines with all poles and alternate poles wound, and different combinations of stator and rotor pole numbers. Design\\/methodology\\/approach – The coil-emf vectors, which are widely used for analyzing the conventional fractional-slot PM machines with non-overlapping windings,

Jin-Tao Chen; Zi-Qiang Zhu

2011-01-01

33

Doubly-fed induction machine models for stability assessment of wind farms  

Microsoft Academic Search

The increasing size of wind farms requires power system stability analysis including dynamic models of the wind power generation. Nowadays, the most widely used generator type for units above 1 MW is the doubly-fed induction machine. Doubly-fed induction machines allow active and reactive power control through a rotor-side converter, while the stator is directly connected to the grid. Detailed models

Markus A. Poller

2003-01-01

34

Analysis of a concentrated winding induction machine for adjustable speed drive applications. I. Motor analysis  

Microsoft Academic Search

The performance of multiphase machines designed for operation with static power converters is investigated. The winding distributions are intentionally rectangular to better accommodate the rectangular waveforms of solid-state inverters. Equations which define the transient as well as steady-state behavior, including the computation of all machine inductances, are derived. In deriving these equations the space harmonics are specifically included. Equations for

Hamid A. Toliyat; T.A. Lipo; J. C. White

1991-01-01

35

Analytical Prediction of Eddy-Current Loss in Armature Windings of Permanent Magnet Brushless AC Machines  

Microsoft Academic Search

This paper presents an analytical model for prediction of eddy current loss in armature windings of permanent magnet brushless AC machines. The developed model can either be used in the case of internal or external rotor radial-field machines topologies. First, a 2-D exact analytical solution of magnetic field distribution in an actual geometry of slotted surface mounted PM radial flux

Yacine Amara; Pascal Reghem; Georges Barakat

2010-01-01

36

On the design of dual-stator windings for safe VSI fed AC machine drives  

Microsoft Academic Search

The major drawback of usual dual-stator AC machines supplied by a voltage source inverter (VSI) is the occurrence of large circulating harmonic currents, causing extra losses. This paper deals with the design of dual-stator winding AC machines for safe operation with VSI. A new reference frame model of a dual-stator induction machine (DSIM), including mutual leakage coupling, is proposed. The

D. Hadiouche; H. Razik; A. Rezzoug

2001-01-01

37

Lumped parameter magnetic circuit model for fractional-slot concentrated-winding interior permanent magnet machines  

Microsoft Academic Search

This paper presents a simplified lumped-parameter magnetic circuit model (MCM) of a fractional-slot concentrated-winding (FSCW) interior permanent magnet (IPM) machine that provides rapid estimates of machine performance for use in machine design optimization software. This model incorporates several key nonlinear phenomena including (i) magnetic saturation; (ii) cross-saturation effects between the d- and q-axes affecting both flux linkages and inductances; (iii)

Jagadeesh K. Tangudu; Thomas M. Jahns; Ayman EL-Refaie; Z. Q. Zhu

2009-01-01

38

Algorithmic method of design and analysis of fractional-slot windings of AC machines  

Microsoft Academic Search

Contents The paper presents a new algorithmic method of designing fractional-slot windings for AC machines of the double and single layer type. The method allows to design windings with a small number of slots per pole and phase, and then to analyse their MMF harmonic spectra in a simple systematic way and to optimise the construction. The presented method comprises

Piotr Wach

1998-01-01

39

The use of time domain spectroscopy as a diagnostic tool for rotating machine windings  

Microsoft Academic Search

In order to assess stator winding insulation condition, a field instrument measuring the charge and the discharge current flowing through rotating machine stator winding groundwall insulation was developed at Hydro-Quebec. This instrument applies a constant DC-voltage of 1 kV during a certain time, usually 2000 s. Immediately following the charging, the stator winding is short-circuited during another period of time.

Eric David; Laurent Lamarre; Duc Ngoc Nguyen

2002-01-01

40

Development of Special Winding Machine for HT-7U Superconducting Tokamak  

NASA Astrophysics Data System (ADS)

A special winding machine with high accuracy has just been developed and applied to the construction of HT-7U Tokamak. It is one of the critical facilities for R & D of HT-7U construction. The machine mainly consists of five parts, including a CICC pay-off spool, a four-roller correcting assembly, a four-roller forming/bending assembly, a continuous winding structure and a CNC control system with three-axis AC servo motors. The facility is used for Cable in Conduit Conductor (CICC) magnet fabrication of HT-7U. The main requirements of the winding machine are: continuous winding to reduce joints inside the coils; pre-forming CICC conductor to avoid winding with tension; suitable for all TF & PF coils of various coil shapes and within the dimension limit; improving the configuration tolerance and the special flatness of the CICC conductor. This paper emphasizes on the design and fabrication of the special winding machine for HT-7U. Some analyses and techniques in winding process for trial D-shape coil are also presented.

Gao, Da-ming; Yu, Jie; Zhu, Wen-hua; Wen, Jun; Pan, Yin-nian; Chen, Le-ping; Tao, Yu-ming; Wang, Hai-jing; He, Wei

2000-02-01

41

Technological and economical analysis of salient pole and permanent magnet synchronous machines designed for wind turbines  

NASA Astrophysics Data System (ADS)

Chinese export restrictions already reduced the planning reliability for investments in permanent magnet wind turbines. Today the production of permanent magnets consumes the largest proportion of rare earth elements, with 40% of the rare earth-based magnets used for generators and other electrical machines. The cost and availability of NdFeB magnets will likely determine the production rate of permanent magnet generators. The high volatility of rare earth metals makes it very difficult to quote a price. Prices may also vary from supplier to supplier to an extent of up to 50% for the same size, shape and quantity with a minor difference in quality. The paper presents the analysis and the comparison of salient pole with field winding and of peripheral winding synchronous electrical machines, presenting important advantages. A neodymium alloy magnet rotor structure has been considered and compared to the salient rotor case. The Salient Pole Synchronous Machine and the Permanent Magnet Synchronous Machine were designed so that the plate values remain constant. The Eddy current effect on the windings is taken into account during the design, and the efficiency, output power and the air-gap flux density obtained after the simulation were compared. The analysis results clearly indicate that Salient Pole Synchronous Machine designs would be attractive to wind power companies. Furthermore, the importance of the design of electrical machines and the determination of criteria are emphasized. This paper will be a helpful resource in terms of examination and comparison of the basic structure and magnetic features of the Salient Pole Synchronous Machine and Permanent Magnet Synchronous Machine. Furthermore, an economic analysis of the designed machines was conducted.

Gündo?du, Tayfun; Kömürgöz, Güven

2012-08-01

42

Regulation of small wind machines: a local perspective  

SciTech Connect

The most common wind turbine issues that communities are concerned about and therefore might address in an ordnance are identified. These issues include noise, safety, communications interference, aesthetics, wind access, and height restrictions. How communities have addressed these issues as well as their approaches for dealing with small wind turbines in general are examined. In particular, the Riverside County, California, an ordinance recently prepared is explained in detail.

Perkins-Smith, D. (Black Hawk Associates, Denver, CO); Odland, R.

1982-01-01

43

Development status of rotating machines employing superconducting field windings  

Microsoft Academic Search

Superconducting rotating machines have looked promising since multifilamentary niobium-titanium (NbTi) superconductors became available in the mid-1960s. Both dc homopolar and ac synchronous machines were successfully tested from the 1970s to the 1990s. Three different 70-MW generators were recently demonstrated by the SuperGM project in Japan. However, economic considerations with respect to competitive cost combined with the requirement for liquid helium

SWARN S. KALSI; KONRAD WEEBER; H. Takesue; CLIVE LEWIS; HEINZ-WERNER NEUMUELLER; RICHARD D. BLAUGHER

2004-01-01

44

Using machine learning to predict wind turbine power output  

NASA Astrophysics Data System (ADS)

Wind turbine power output is known to be a strong function of wind speed, but is also affected by turbulence and shear. In this work, new aerostructural simulations of a generic 1.5 MW turbine are used to rank atmospheric influences on power output. Most significant is the hub height wind speed, followed by hub height turbulence intensity and then wind speed shear across the rotor disk. These simulation data are used to train regression trees that predict the turbine response for any combination of wind speed, turbulence intensity, and wind shear that might be expected at a turbine site. For a randomly selected atmospheric condition, the accuracy of the regression tree power predictions is three times higher than that from the traditional power curve methodology. The regression tree method can also be applied to turbine test data and used to predict turbine performance at a new site. No new data are required in comparison to the data that are usually collected for a wind resource assessment. Implementing the method requires turbine manufacturers to create a turbine regression tree model from test site data. Such an approach could significantly reduce bias in power predictions that arise because of the different turbulence and shear at the new site, compared to the test site.

Clifton, A.; Kilcher, L.; Lundquist, J. K.; Fleming, P.

2013-06-01

45

Research on Potential of Advanced Technology for Housing. A Building System Based on Filament Winding and New Developments in Water and Waste Management.  

ERIC Educational Resources Information Center

The University of Michigan and Aerojet Corporation report their development of a new building system which will offer the consumer a higher quality product at lower cost. To achieve this goal, the University-Aerojet proposal suggested filament winding (a process derived from the aerospace program for the manufacture of reinforced plastic…

Michigan Univ., Ann Arbor.

46

Numerically Controlled Machining Of Wind-Tunnel Models  

NASA Technical Reports Server (NTRS)

New procedure for dynamic models and parts for wind-tunnel tests or radio-controlled flight tests constructed. Involves use of single-phase numerical control (NC) technique to produce highly-accurate, symmetrical models in less time.

Kovtun, John B.

1990-01-01

47

Dynamic modelling and analysis of multi-machine power systems including wind farms  

NASA Astrophysics Data System (ADS)

This thesis introduces a small-signal dynamic model, based on a frequency response approach, for the analysis of a multi-machine power system with special focus on an induction machine based wind farm. The proposed approach is an alternative method to the conventional eigenvalue analysis method which is widely employed for small-signal dynamic analyses of power systems. The proposed modelling approach is successfully applied and evaluated for a power system that (i) includes multiple synchronous generators, and (ii) a wind farm based on either fixed-speed, variable-speed, or doubly-fed induction machine based wind energy conversion units. The salient features of the proposed method, as compared with the conventional eigenvalue analysis method, are: (i) computational efficiency since the proposed method utilizes the open-loop transfer-function matrix of the system, (ii) performance indices that are obtainable based on frequency response data and quantitatively describe the dynamic behavior of the system, and (iii) capability to formulate various wind energy conversion unit, within a wind farm, in a modular form. The developed small-signal dynamic model is applied to a set of multi-machine study systems and the results are validated based on comparison (i) with digital time-domain simulation results obtained from PSCAD/EMTDC software tool, and (ii) where applicable with eigenvalue analysis results.

Tabesh, Ahmadreza

2005-11-01

48

Filamentation Instability of Interacting Current Sheets in Striped Relativistic Winds: The Origin of Low Sigma?  

E-print Network

I outline a mechanism, akin to Weibel instabilities of interpenetrating beams, in which the neighboring current sheets in a striped wind from an oblique rotator interact through a two stream-like mechanism (a Weibel instability in flatland), to create an anomalous resistivity that heats the sheets and causes the magnetic field to diffusively annihilate in the wind upstream of the termination shock. The heating has consequences for observable unpulsed emission from pulsars.

Jonathan Arons

2007-10-28

49

Short Circuit Analysis of Induction Machines Wind Power Application  

SciTech Connect

he short circuit behavior of Type I (fixed speed) wind turbine-generators is analyzed in this paper to aid in the protection coordination of wind plants of this type. A simple network consisting of one wind turbine-generator is analyzed for two network faults: a three phase short circuit and a phase A to ground fault. Electromagnetic transient simulations and sequence network calculations are compared for the two fault scenarios. It is found that traditional sequence network calculations give accurate results for the short circuit currents in the balanced fault case, but are inaccurate for the un-faulted phases in the unbalanced fault case. The time-current behavior of the fundamental frequency component of the short circuit currents for both fault cases are described, and found to differ significantly in the unbalanced and balanced fault cases

Starke, Michael R [ORNL; Smith, Travis M [ORNL; Howard, Dustin [Georgia Institute of Technology; Harley, Ronald [Georgia Institute of Technology

2012-01-01

50

A Mars 1 Watt vortex wind energy machine  

NASA Astrophysics Data System (ADS)

A Martian wind power generator capable of surviving impact and fulfilling the long-term (2-5 yr) low-level power requirements (1-2 W) of an unmanned surface probe is presented. Attention is given to a tornado vortex generator that was chosen on the basis of its capability to theoretically augment the available power that may be extracted for average Martian wind speeds of about 7.5 m/s. The generator offers comparable mass-to-power ratios with solar power sources.

Ralston, Michael; Crowley, Christopher; Thomson, Ronald; Gwynne, Owen

51

A Mars 1 Watt vortex wind energy machine  

NASA Technical Reports Server (NTRS)

A Martian wind power generator capable of surviving impact and fulfilling the long-term (2-5 yr) low-level power requirements (1-2 W) of an unmanned surface probe is presented. Attention is given to a tornado vortex generator that was chosen on the basis of its capability to theoretically augment the available power that may be extracted for average Martian wind speeds of about 7.5 m/s. The generator offers comparable mass-to-power ratios with solar power sources.

Ralston, Michael; Crowley, Christopher; Thomson, Ronald; Gwynne, Owen

1992-01-01

52

Armature reaction effects on a high temperature superconducting field winding of an synchronous machine: experimental results  

NASA Astrophysics Data System (ADS)

This paper presents experimental results from the Superwind laboratory setup. Particular focus in the paper has been placed on describing and quantifying the influence of armature reaction on performance of the HTS filed winding. Presented experimental results have confirmed the HTS field winding sensitivity to both armature reaction intensity and angular position with respect to the HTS coils. Furthermore, the characterization of the HTS field winding has been correlated to the electromagnetic torque of the machine where the maximal Ic reduction of 21% has been observed for the maximum torque.

Mijatovic, Nenad; Jensen, Bogi Bech

2014-05-01

53

A Basic Study of Wind Generator Stabilization with Doubly-Fed Asynchronous Machine  

NASA Astrophysics Data System (ADS)

This paper investigates the function of DASM (Doubly-fed ASynchronous Machine) with emphasis placed on its ability to the stabilization of the power system including wind generators. P (active power) and Q (reactive power) compensation from DASM can be regulated independently through secondary-excitation controlling. Simulation results by PSCAD show that DASM can restore the wind-generator system to a normal operating condition rapidly even following severe transmission-line failures. Comparison studies have also been performed between wind turbine pitch control and proposed method.

Wu, Li; Takahashi, Rion; Nakagawa, Masaki; Murata, Toshiaki; Tamura, Junji

54

Analysis of concentrated winding induction machines for adjustable speed drive applications-experimental results  

Microsoft Academic Search

An approach to an analysis of multiphase concentrated winding induction machines specifically designed for operation with static power converters has been presented and simulated by means of a digital computer simulation in previous papers. In order to substantiate the theoretical conclusions regarding the performance of multiphase induction motors, an experimental five phase induction motor and its corresponding power converter and

Hamid A. Toliyat; T.A. Lipo

1994-01-01

55

System for maintaining the alignment of mandrels in filament winding operations  

DOEpatents

The present invention is directed to a system for sensing and correcting the alignment of a mandrel being wound with filamentary material with respect to the filamentary material winding mechanism. A positioned reference pin attached to the mandrel is positioned in a beam of collimated light emanating from a laser so as to bisect the light beam and create a shadow therebetween. A pair of photocells are positioned to receive the bisected light beam with the shadow uniformly located between the photocells when the pin is in a selected position. The mandrel is supported in the selected position for the winding of a filamentary material by a position adjustable roller mechanism which is coupled by a screw drive to a reversible motor. Changes in the pin position such as caused by winding growth are sensed by the photocells to provide the displacement of the roller mechanism in the direction necessary to return the mandrel to the selected position.

Robinson, Samuel C. (Clinton, TN); Dodge, William G. (Oak Ridge, TN); Pollard, Roy E. (Powell, TN)

1984-01-01

56

Wind machines for the California Aqueduct. Volume I. Executive summary  

Microsoft Academic Search

The California Aqueduct is a 684-mile long water system including natural waterways and a 444-mile length of canal and tunnel, that delivers water from the mountains of Northern California to arid Southern California for agricultural, industrial and residential use. The objective of the study was to examine the applicability of wind energy conversion systems to meet a part of the

Lindley

1977-01-01

57

Field study of the aesthetics of small wind machines: a preliminary report  

SciTech Connect

A field study was conducted at the Rocky Flats Small Wind Systems Test Center to determine if aesthetic preferences exist for particular designs of small wind machines, and to gather data on the importance of aesthetics relative to other wind system issues. Participants on public tours of the Test Center were asked to answer several general questions and to rate the visual appearance of various working parts (rotor and nacelle), towers, and complete machines. Working parts included vertical- and horizontal-axis designs (both upwind and downwind), while towers included wood, concrete and steel columns, and various truss designs. In spite of a relatively small sample size (N = 139), the results indicate definite preferences for particular designs, with downwind horizontal-axis working parts and columnar towers receiving the highest ratings.

Strojan, C. L.; Lawrence, K.; O'Donnell, D.

1980-03-01

58

Multi-star multi-phase winding for a high power naval propulsion machine with low ripple torques  

E-print Network

1 Multi-star multi-phase winding for a high power naval propulsion machine with low ripple torques with a fractional-slot concentrated winding made up of four 3-phase windings each one being star-connected, each star being magnetically shifted by an angle of 15 degrees. This 4-star 3-phase configuration allows

Boyer, Edmond

59

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

60

Flexible filaments in a flowing soap film as a model for one-dimensional flags in a two-dimensional wind  

NASA Astrophysics Data System (ADS)

The dynamics of swimming fish and flapping flags involves a complicated interaction of their deformable shapes with the surrounding fluid flow. Even in the passive case of a flag, the flag exerts forces on the fluid through its own inertia and elastic responses, and is likewise acted on by hydrodynamic pressure and drag. But such couplings are not well understood. Here we study these interactions experimentally, using an analogous system of flexible filaments in flowing soap films. We find that, for a single filament (or `flag') held at its upstream end and otherwise unconstrained, there are two distinct, stable dynamical states. The first is a stretched-straight state: the filament is immobile and aligned in the flow direction. The existence of this state seems to refute the common belief that a flag is always unstable and will flap. The second is a flapping state: the filament executes a sinuous motion in a manner akin to the flapping of a flag in the wind. We study further the hydrodynamically coupled interaction between two such filaments, and demonstrate the existence of four different dynamical states.

Zhang, Jun; Childress, Stephen; Libchaber, Albert; Shelley, Michael

2000-12-01

61

Surface Wind Speed Prediction in the Canadian Arctic using Non-Linear Machine Learning Methods  

Microsoft Academic Search

Two non-linear, machine-learning\\/statistical methods, i.e., Bayesian neural network (BNN) and support vector regression (SVR), plus multiple linear regression (MLR), were used to forecast surface wind speeds at lead times of 12, 24, 48 and 72 h. Three different schemes, a statistical downscaling model (Scheme 1) using daily reforecast data from the National Centers for Environmental Prediction (NCEP) Global Forecasting System (GFS),

Zhen Zeng; William W. Hsieh; William R. Burrows; Andrew Giles; Amir Shabbar

2011-01-01

62

Fault diagnosis of direct-drive wind turbine based on support vector machine  

NASA Astrophysics Data System (ADS)

A fault diagnosis method of direct-drive wind turbine based on support vector machine (SVM) and feature selection is presented. The time-domain feature parameters of main shaft vibration signal in the horizontal and vertical directions are considered in the method. Firstly, in laboratory scale five experiments of direct-drive wind turbine with normal condition, wind wheel mass imbalance fault, wind wheel aerodynamic imbalance fault, yaw fault and blade airfoil change fault are carried out. The features of five experiments are analyzed. Secondly, the sensitive time-domain feature parameters in the horizontal and vertical directions of vibration signal in the five conditions are selected and used as feature samples. By training, the mapping relation between feature parameters and fault types are established in SVM model. Finally, the performance of the proposed method is verified through experimental data. The results show that the proposed method is effective in identifying the fault of wind turbine. It has good classification ability and robustness to diagnose the fault of direct-drive wind turbine.

An, X. L.; Jiang, D. X.; Li, S. H.; Chen, J.

2011-07-01

63

Current-based sensorless detection of stator winding turn faults in induction machines  

NASA Astrophysics Data System (ADS)

To improve the reliability of motor-driven processes, condition monitoring of electric machines has received considerable attention from industry. For small- and medium-sized machines, the focus is on low-cost sensorless schemes that use only measured voltages and currents for fault diagnostics. Turn faults arising from stator winding insulation deterioration account for a large percentage of motor failures. The objective of a turn-fault detection scheme is to provide a warning before the fault propagates further and results in ground current, causing irreversible damage to the magnetic material. In this work, a neural-network-based robust scheme for early detection of turn faults in induction machines is developed. The negative-sequence component of line currents is used as the fault signature, and a neural network is trained to compensate for the effects of unbalanced supply voltages and nonidealities in the machine or instrumentation. Novel training algorithms for self-commissioning and on-line training of the neural network have also been developed. Experimental results, obtained on a specially-rewound machine, are provided to demonstrate that the method is capable of early fault detection. Data memory and computational requirements are also minimal, making the scheme viable for commercial implementation. The method is also extended to turn-fault detection in open-loop inverter-fed induction machines. Data obtained from a thermally accelerated insulation failure experiment is also used to test the performance and sensitivity of the method, and to show that a turn fault can be detected before failure of insulation to ground.

Tallam, Rangarajan M.

64

A novel design of DC-AC electrical machine rotary converter for hybrid solar and wind energy applications  

NASA Astrophysics Data System (ADS)

This paper proposes the design of a new bi-directional DC-AC rotary converter machine to convert a d.c. voltage to three-phase voltage and vice-versa using a two-stage energy conversion machine. The rotary converter consists of two main stages which are combined into single frame. These two stages are constructed from three main electromagnetic components. The first inner electromagnetic component represents the input stage that enables the DC power generated by solar energy from photo-voltaic cells to be transformed by the second and third components electro-magnetically to produce multi-phase voltages at the output stage. At the same time, extra kinetic energy from wind, which is sufficiently available, can be added to existing torque on the second electromagnetic component. Both of these input energies will add up to the final energy generated at the output terminals. Therefore, the machine will be able to convert solar and wind energies to the output terminals simultaneously. If the solar energy is low, the available wind energy will be able to provide energy to the output terminals and at the same time charges the batteries which are connected as backup system. At this moment, the machine behaves as wind turbine. The energy output from the machine benefits from two energy sources which are solar and wind. At night when the solar energy is not available and also the load is low, the wind energy is able to charge the batteries and at the same time provides output electrical power to the remaining the load. Therefore, the proposed system will have high usage of available renewable energy as compared to separated wind or solar systems. MATLAB codes are used to calculate the required dimensions, the magnetic and electrical circuits parameters to design of the new bi-directional rotary converter machine.

Mohammed, K. G.; Ramli, A. Q.; Amirulddin, U. A. U.

2013-06-01

65

Fluid-structure interaction modeling of wind turbines: simulating the full machine  

NASA Astrophysics Data System (ADS)

In this paper we present our aerodynamics and fluid-structure interaction (FSI) computational techniques that enable dynamic, fully coupled, 3D FSI simulation of wind turbines at full scale, and in the presence of the nacelle and tower (i.e., simulation of the "full machine"). For the interaction of wind and flexible blades we employ a nonmatching interface discretization approach, where the aerodynamics is computed using a low-order finite-element-based ALE-VMS technique, while the rotor blades are modeled as thin composite shells discretized using NURBS-based isogeometric analysis (IGA). We find that coupling FEM and IGA in this manner gives a good combination of efficiency, accuracy, and flexibility of the computational procedures for wind turbine FSI. The interaction between the rotor and tower is handled using a non-overlapping sliding-interface approach, where both moving- and stationary-domain formulations of aerodynamics are employed. At the fluid-structure and sliding interfaces, the kinematic and traction continuity is enforced weakly, which is a key ingredient of the proposed numerical methodology. We present several simulations of a three-blade 5~MW wind turbine, with and without the tower. We find that, in the case of no tower, the presence of the sliding interface has no effect on the prediction of aerodynamic loads on the rotor. From this we conclude that weak enforcement of the kinematics gives just as accurate results as the strong enforcement, and thus enables the simulation of rotor-tower interaction (as well as other applications involving mechanical components in relative motion). We also find that the blade passing the tower produces a 10-12 % drop (per blade) in the aerodynamic torque. We feel this finding may be important when it comes to the fatigue-life analysis and prediction for wind turbine blades.

Hsu, Ming-Chen; Bazilevs, Yuri

2012-12-01

66

Modeling and analysis of proximity losses in high-speed surface permanent magnet machines with concentrated windings  

Microsoft Academic Search

Surface permanent magnet (SPM) machines can be designed with fractional slot-concentrated windings (FSCW) to achieve extended speed ranges. High-speed operation can lead to significant levels of proximity losses in the stator windings due to substantial spatial harmonic magnetic fields in the air-gap as well as the high-frequency currents themselves. An integrated analysis tool is presented in this paper to calculate

Patel B. Reddy; T. M. Jahns; T. P. Bohn

2010-01-01

67

Induction machine  

DOEpatents

A polyphase rotary induction machine for use as a motor or generator utilizing a single rotor assembly having two series connected sets of rotor windings, a first stator winding disposed around the first rotor winding and means for controlling the current induced in one set of the rotor windings compared to the current induced in the other set of the rotor windings. The rotor windings may be wound rotor windings or squirrel cage windings.

Owen, Whitney H. (Ogden, UT)

1980-01-01

68

Analysis of a concentrated winding induction machine for adjustable speed drive applications. II. Motor design and performance  

Microsoft Academic Search

For pt.I. see ibid, vol.6, no.4, p.679-83 (1991). The performance of multiphase machines designed for operation with static power converters is described. The winding distributions are intentionally rectangular to better accommodate the rectangular waveforms of solid-state inverters. Fourier analysis is used for investigation of the effects of different air-gap-field spatial distributions and time harmonics in the supply. The approach to

Hamid A. Toliyat; T.A. Lipo; J. C. White

1991-01-01

69

Effects of Aerospace Contaminants on EPIKOTE(TM) 862 / EPIKURE(TM)-W Filament Winding Resin System: An Experimental Study  

NASA Astrophysics Data System (ADS)

This thesis presents the findings of extensive experiments to determine the effects of various common aerospace chemicals on EPIKOTE(TM) 862 (resin) and EPIKURE(TM) W (curing agent), a resin system utilized in filament wound carbon fiber reinforced polymer (CRP) structures. Test specimens of the neat resin system were fabricated and exposed for up to 6 months at room temperature to 11 fluids representing typical aerospace chemicals found on the flight line, and to 74°C tap water. Post exposure the samples were tested in torsion using a rheometer, which performed strain sweeps and frequency sweeps on all the samples. In addition, a subset of the samples received a temperatures sweep. The rheology test parameters represented the nominal stress levels CRP structures would expect to see in operation. In addition to the rheological tests, dimensional and mass measurements were made of the samples both pre and post exposure to study the physical changes due to the chemical interactions. Based on the results, a common detergent, MEK on structures manufactured with the 862W resin system should be prevented or severely limited. It had a significant impact on the performance of the resin system within 3 months, with no visible indications of the degradation. The resins system had good chemical resistance to all the other chemicals used in this study including hot water.

Moffet, Mitchell Lee

70

Filament disappearances  

NASA Technical Reports Server (NTRS)

The phenomenon of the sudden filament disappearance (Disparition Brusque) is a familiar one to observers at H alpha telescopes. Nevertherless, the importance in Disparition Brusques (DB) continues to grow for several reasons which are cited in the discussion. It is reported that there seems to be more interest on building and maintain filaments than in destroying them. As a consequence, this sub-group is smaller than most of the others. All the same, progress in this area of filament disapperences seems steady and assured. The importance and interest in DBs is discussed and future directions are indicated.

Wagner, William J.

1986-01-01

71

Helical filaments  

NASA Astrophysics Data System (ADS)

The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

Barbieri, Nicholas; Hosseinimakarem, Zahra; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Johnson, Eric; Richardson, Martin

2014-06-01

72

Helical filaments  

SciTech Connect

The shaping of laser-induced filamenting plasma channels into helical structures by guiding the process with a non-diffracting beam is demonstrated. This was achieved using a Bessel beam superposition to control the phase of an ultrafast laser beam possessing intensities sufficient to induce Kerr effect driven non-linear self-focusing. Several experimental methods were used to characterize the resulting beams and confirm the observed structures are laser air filaments.

Barbieri, Nicholas; Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin [Townes Laser Institute, CREOL—The College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States); Hosseinimakarem, Zahra; Johnson, Eric [Micro-Photonics Laboratory – Center for Optical Material Science, Clemson, Anderson, South Carolina 29634 (United States)

2014-06-30

73

Magnetically driven filament probe.  

PubMed

A radially movable probe has been developed for studies of filamentary transport in ASDEX Upgrade during edge localized modes (ELMs) by means of Langmuir tips and magnetic pickup coils. The probe is permanently installed at the low field side in the ASDEX Upgrade vacuum vessel and is not subject to limitations in probe size, as, for example, probes on a shared manipulator are. The probe is moved by a magnetic drive, which allows for easy installation in the vessel, and has moderate machine requirements, as it will only require an electric feedthrough and an external power supply. The drive gives a linear motion with a radial range of 5 cm within 50 ms, where range and velocity can be largely scaled according to experimental requirements. The probe has been installed in the outer midplane of the ASDEX Upgrade vessel, where ELM filaments are expected to have their maximum amplitude. Filaments are coherent substructures within an ELM, carrying a fraction of the ELM released energy towards the wall. The new probe allows to measure the structure of these filaments, in particular, parameters such as filament rotation (by time delay measurements) and size (by peak width analysis). Activating the drive moves the probe from a safe position behind the limiter to a position in front of the limiters, i.e., exposes the Langmuir pins to the scrape-off layer plasma. PMID:17552815

Schmid, A; Herrmann, A; Rohde, V; Maraschek, M; Müller, H W

2007-05-01

74

SBC: Filamentality  

NSDL National Science Digital Library

Filamentality is a tool offered by SBC (that's right, the phone company) as part of its education program and the Knowledge Network Explorer (KNE) website. The tool is meant to help educators (classroom teachers, trainers, students, or librarians) create Web-based activities. Basically, Filamentality is "a fill-in-the-blank tool that guides you through picking a topic, searching the Web, gathering good Internet links, and turning them into learning activities." The idea is to "combine the 'filament' of the Web with a learner's 'mentality.'" Setting up your own website is free and the process is explained so that you can get started with little or no knowledge of HTML or how the Web works. The Search Filamentality section lets visitors find some websites already created using Filamentality (i.e.: a search for "mathematics" brought up 1396 different websites), as well as related resources offered through the Knowledge Network Explorer. The Activity Formats section provides some suggestions and examples for ways to organize your educational website.

75

Understanding Power Electronics and Electrical Machines in Multidisciplinary Wind Energy Conversion System Courses  

ERIC Educational Resources Information Center

Wind energy conversion systems (WECS) nowadays offer an extremely wide range of topologies, including various different types of electrical generators and power converters. Wind energy is also an application of great interest to students and with a huge potential for engineering employment. Making WECS the main center of interest when teaching…

Duran, M. J.; Barrero, F.; Pozo-Ruz, A.; Guzman, F.; Fernandez, J.; Guzman, H.

2013-01-01

76

Impact of Winding Layer Number and Slot\\/Pole Combination on AC Armature Losses of Synchronous Surface PM Machines Designed for Wide Constant-Power Speed Range Operation  

Microsoft Academic Search

This paper examines the impact of the winding layer number (single- and double-layer), and magnet type (sintered and bonded), as well as slot\\/pole combinations on AC stator losses in surface permanent magnet (SPM) synchronous machines equipped with fractional-slot concentrated windings that are designed for wide speed ranges of constant-power operation. It is shown that the use of bonded magnets instead

Patel B. Reddy; T. M. Jahns; Ayman M. El-Refaie

2008-01-01

77

Control strategies for enhanced power smoothing in wind energy systems using a flywheel driven by a vector-controlled induction machine  

Microsoft Academic Search

This paper presents a novel control strategy for power smoothing in wind energy applications, especially those feeding a stand-alone load. The system is based on a vector-controlled induction machine driving a flywheel and addresses the problem of regulating the DC-link system voltage against both input power surges\\/sags from a wind turbine or sudden changes in load demand. The control is

Roberto Cárdenas; Rubén Peña; Greg Asher; Jon Clare

2001-01-01

78

Partial discharge characteristics of enameled wire of electric machine winding under exploitation stresses  

Microsoft Academic Search

In applications where power electronic converters are used, the voltage stress has a form of fast switching pulses composing of repetitive sequences. Such conditions have influence on inception and development of partial discharges in insulating systems of electrical machines subjected to non-sinusoidal waveform. The paper presents the dependence of partial discharge parameters and partial discharge patterns upon kinds of magnet

B. Florkowska; J. Roehrich; P. Zydron; M. Florkowski

2010-01-01

79

Modes of operation of the slip ring induction machine in wind energy conversion systems  

Microsoft Academic Search

Two modes of operation of the slip ring induction machine are investigated: the double-output induction generator (DOIG) and the double-excited induction generator. The output power, power factor, efficiency, system displacement angle, and firing angle of the two are compared. An optimal scheme of operation combining both modes is proposed. It is shown that the power generated by the DEIG is

M. T. El Hagry; A. A. Mohamed; M. N. Iskander

1989-01-01

80

Analysis of strong nocturnal shears for wind machine design. Final report  

SciTech Connect

Wind shear data at wind turbine heights from several sites is reviewed and new data is documented in terms of total and component shear. A variety of atmospheric scenarios may combine to give large persistent shear. Among these, strong boundary layer stability is foremost. It occurs with strong nocturnal surface cooling, in low level frontal and subsidence inversions, and in thunderstorm outflows. Strong shears resulting from surface radiation inversions are particularly evident over the High Plains where dry air and high altitude combine to result in strong radiational cooling. Terrain is also an important influence on shear but it is not well understood and is very site specific.

Mahrt, L.; Heald, R.C.

1980-11-01

81

Final Report on Control Algorithm to Improve the Partial-Load Efficiency of Surface PM Machines with Fractional-Slot Concentrated Windings  

SciTech Connect

Surface permanent magnet (SPM) synchronous machines using fractional-slot concentrated windings are being investigated as candidates for high-performance traction machines for automotive electric propulsion systems. It has been shown analytically and experimentally that such designs can achieve very wide constant-power speed ratios (CPSR) [1,2]. This work has shown that machines of this type are capable of achieving very low cogging torque amplitudes as well as significantly increasing the machine power density [3-5] compared to SPM machines using conventional distributed windings. High efficiency can be achieved in this class of SPM machine by making special efforts to suppress the eddy-current losses in the magnets [6-8], accompanied by efforts to minimize the iron losses in the rotor and stator cores. Considerable attention has traditionally been devoted to maximizing the full-load efficiency of traction machines at their rated operating points and along their maximum-power vs. speed envelopes for higher speeds [9,10]. For example, on-line control approaches have been presented for maximizing the full-load efficiency of PM synchronous machines, including the use of negative d-axis stator current to reduce the core losses [11,12]. However, another important performance specification for electric traction applications is the machine's efficiency at partial loads. Partial-load efficiency is particularly important if the target traction application requires long periods of cruising operation at light loads that are significantly lower than the maximum drive capabilities. While the design of the machine itself is clearly important, investigation has shown that this is a case where the choice of the control algorithm plays a critical role in determining the maximum partial-load efficiency that the machine actually achieves in the traction drive system. There is no evidence that this important topic has been addressed for this type of SPM machine by any other authors. This topic takes on even greater significance for fractional-slot concentrated-winding SPM machine designs. In particular, maximizing the torque/power density of this class of SPM machines typically leads to machine designs with high numbers of poles. The resulting high electrical frequencies can easily result in high stator core losses unless special care is taken during the machine design process. The purpose of this report is to discuss a modified vector control algorithm for a fractional-slot concentrated winding SPM machine that has been developed to maximize the machine's partial-load efficiency over a wide range of operating conditions. For purposes of this discussion, a 55 kW (peak) SPM machine designed to meet requirements established in the US FreedomCar program [13] is used as the basis for demonstrating the proposed technique. A combination of closed-form analysis [14] and finite element analysis (FEA) is used during this investigation.

McKeever, John W [ORNL; Reddy, Patel [University of Wisconsin; Jahns, Thomas M [ORNL

2007-05-01

82

FINAL REPORT ON CONTROL ALGORITHM TO IMPROVE THE PARTIAL-LOAD EFFICIENCY OFSURFACE PM MACHINES WITH FRACTIONAL-SLOT CONCENTRATED WINDINGS  

SciTech Connect

Surface permanent magnet (SPM) synchronous machines using fractional-slot concentrated windings are being investigated as candidates for high-performance traction machines for automotive electric propulsion systems. It has been shown analytically and experimentally that such designs can achieve very wide constant-power speed ratios (CPSR) [1,2]. This work has shown that machines of this type are capable of achieving very low cogging torque amplitudes as well as significantly increasing the machine power density [3-5] compared to SPM machines using conventional distributed windings. High efficiency can be achieved in this class of SPM machine by making special efforts to suppress the eddy-current losses in the magnets [6-8], accompanied by efforts to minimize the iron losses in the rotor and stator cores. Considerable attention has traditionally been devoted to maximizing the full-load efficiency of traction machines at their rated operating points and along their maximum-power vs. speed envelopes for higher speeds [9,10]. For example, on-line control approaches have been presented for maximizing the full-load efficiency of PM synchronous machines, including the use of negative d-axis stator current to reduce the core losses [11,12]. However, another important performance specification for electric traction applications is the machine's efficiency at partial loads. Partial-load efficiency is particularly important if the target traction application requires long periods of cruising operation at light loads that are significantly lower than the maximum drive capabilities. While the design of the machine itself is clearly important, investigation has shown that this is a case where the choice of the control algorithm plays a critical role in determining the maximum partial-load efficiency that the machine actually achieves in the traction drive system. There is no evidence that this important topic has been addressed for this type of SPM machine by any other authors. This topic takes on even greater significance for fractional-slot concentrated-winding SPM machine designs. In particular, maximizing the torque/power density of this class of SPM machines typically leads to machine designs with high numbers of poles. The resulting high electrical frequencies can easily result in high stator core losses unless special care is taken during the machine design process. The purpose of this report is to discuss a modified vector control algorithm for a fractional-slot concentrated winding SPM machine that has been developed to maximize the machine's partial-load efficiency over a wide range of operating conditions. For purposes of this discussion, a 55 kW (peak) SPM machine designed to meet requirements established in the US FreedomCar program [13] is used as the basis for demonstrating the proposed technique. A combination of closed-form analysis [14] and finite element analysis (FEA) is used during this investigation.

Reddy, P.B.; Jahns, T.M.

2007-04-30

83

Fuzzy logic based intelligent control of a variable speed cage machine wind generation system  

Microsoft Academic Search

The paper describes a variable speed wind generation system where fuzzy logic principles are used for efficiency optimization and performance enhancement control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which pumps power to a utility grid or can supply to an autonomous system. The generation system has fuzzy logic control with

M. G. Simoes; B. K. Bose; R. J. Spiegel

1997-01-01

84

FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM  

EPA Science Inventory

The report gives results of a demonstration of the successful application of fuzzy logic to enhance the performance and control of a variable-speed wind generation system. A squirrel cage induction generator feeds the power to either a double-sided pulse-width modulation converte...

85

Power strategies for maximum control structure of a wind energy conversion system with a synchronous machine  

Microsoft Academic Search

The control of a wind energy conversion system can be decomposed into two parts: a local control depending on the power structure and a global control (strategy) deduced from global considerations. The local part ensures an efficient energy management of each component of the system. The local control structure can be deduced from the Energetic Macroscopic Representation, which is a

A. Bouscayrol; Ph. Delarue; X. Guillaud

2005-01-01

86

Vector controlled induction machines for stand-alone wind energy applications  

Microsoft Academic Search

This paper describes the system and control structures for vector controlled induction generators used for variable speed, wind energy conversion (WEC) systems. The paper focuses on WEC systems feeding an isolated load or weak grid since for such systems the generated voltage and power flow must be regulated by the WEC system itself and the control structures are not trivial.

R. S. Pena; R. J. Cardenas; G. M. Asher; J. C. Clare

2000-01-01

87

Design of Transverse Flux Permanent Magnet Machines for Large Direct-Drive Wind Turbines  

Microsoft Academic Search

In order to maximize the energy harnessed, to minimize the cost, to improve the power quality and to ensure safety together with the growth of the size, various wind turbine concepts have been developed during last three decades. Different generator systems such as geared and direct-drive generator systems have been developed. Based on energy yield, reliability and maintenance problems, direct-drive

D. Bang

2010-01-01

88

FUZZY LOGIC BASED INTELLIGENT CONTROL OF A VARIABLE SPEED CAGE MACHINE WIND GENERATION SYSTEM  

EPA Science Inventory

The paper describes a variable-speed wind generation system where fuzzy logic principles are used to optimize efficiency and enhance performance control. A squirrel cage induction generator feeds the power to a double-sided pulse width modulated converter system which either pump...

89

Graphite filament wound pressure vessels  

NASA Technical Reports Server (NTRS)

Filament wound NOL rings, 4-inch and 8-inch diameter closed-end vessels involving three epoxy resin systems and three graphite fibers were tested to develop property data and fabrication technology for filament wound graphite/epoxy pressure vessels. Vessels were subjected to single-cycle burst tests at room temperature. Manufacturing parameters were established for tooling, winding, and curing that resulted in the development of a pressure/vessel performance factor (pressure x volume/weight) or more than 900,000 in. for an oblate spheroid specimen.

Feldman, A.; Damico, J. J.

1972-01-01

90

Wind  

NSDL National Science Digital Library

What part does the wind play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to wind as an energy source. Here students read about the history, uses, and efficiency of wind power. Information is also provided about benefits, limitations, and geographical considerations of wind power in the United States. Thought-provoking questions afford students chances to reflect on what they've read about the uses of wind power. Supplemental articles and information are available from a sidebar. Three energy-related web links are also provided. Copyright 2005 Eisenhower National Clearinghouse

Iowa Public Television. Explore More Project

2004-01-01

91

Analysis and design of a coreless permanent-magnet machine considering the winding shape by using a lumped equivalent magnetic circuit model  

NASA Astrophysics Data System (ADS)

A simple and rapid analysis and design method is proposed for a coreless permanent magnet machine (CPMM) using a hexagonal winding (HW). The HW, which combines a rectangular winding (RTW) and rhombic winding (RBW), can compensate for the disadvantages and maximize the advantages of the RTW and RBW. The CPMM is typically analyzed using complex differential equations or a timeconsuming finite element analysis (FEA). To address this problem, a relatively simpler and less timeconsuming analysis method is proposed by using a lumped equivalent magnetic circuit (LEMC) model. Furthermore, an effect of winding angle on a motor performance is analyzed via precise inspection of the relationship between the variables of the HW and the characteristics of motor. The validity and usefulness of the proposed method are verified via FEA and experiment.

Seo, Jung-Moo; Jung, In-Soung; Jung, Hyun-Kyo; Ro, Jong-Suk

2014-05-01

92

Application of the AC Commutator Machine in Wind Energy Conversion Systems  

E-print Network

V rq B I = -jI The first and third equations in (38) then became: V = RI +juuLI +ju?I (R +jX)I + jXI (39a) + z L (-jIB) j(uu - mgMI + R I + j(u) - z )L IB jsuZZ + R IB + jsmL IB = j&I. + (R, + j'X, )S (39b) where we have defined: (m - uug s 6... in that equivalent circuit. R s j(X ? X ) R/s jg ? X) I I m VB S Figure 14. Equivalent circuit of induction machine with rotor injected voltage. 45 It ''s wortlmhile at this point to consider the effect of the variation of the injected sec~ voltage...

El-Jamous, Sami Georges

1981-01-01

93

Mars vertical axis wind machines. The design of a Darreus and a Giromill for use on Mars  

NASA Technical Reports Server (NTRS)

This report contains the design of both a Darrieus and a Giromill for use on Mars. The report has been organized so that the interested reader may read only about one machine without having to read the entire report. Where components for the two machines differ greatly, separate sections have been allotted for each machine. Each section is complete; therefore, no relevant information is missed by reading only the section for the machine of interest. Also, when components for both machines are similar, both machines have been combined into one section. This is done so that the reader interested in both machines need not read the same information twice.

Brach, David; Dube, John; Kelly, Jon; Peterson, Joanna; Bollig, John; Gohr, Lisa; Mahoney, Kamin; Polidori, Dave

1992-01-01

94

Mars vertical axis wind machines. The design of a Darreus and a Giromill for use on Mars  

NASA Astrophysics Data System (ADS)

This report contains the design of both a Darrieus and a Giromill for use on Mars. The report has been organized so that the interested reader may read only about one machine without having to read the entire report. Where components for the two machines differ greatly, separate sections have been allotted for each machine. Each section is complete; therefore, no relevant information is missed by reading only the section for the machine of interest. Also, when components for both machines are similar, both machines have been combined into one section. This is done so that the reader interested in both machines need not read the same information twice.

Brach, David; Dube, John; Kelly, Jon; Peterson, Joanna; Bollig, John; Gohr, Lisa; Mahoney, Kamin; Polidori, Dave

1992-05-01

95

Inrush Current Simulation of Power Transformer using Machine Parameters Estimated by Design Procedure of Winding Structure and Genetic Algorithm  

NASA Astrophysics Data System (ADS)

This paper presents estimation techniques of machine parameters for power transformer using design procedure of transformer and genetic algorithm with real coding. Especially, it is very difficult to obtain machine parameters for transformers in customers' facilities. Using estimation techniques, machine parameters could be calculated from the only nameplate data of these transformers. Subsequently, EMTP-ATP simulation of the inrush current was carried out using machine parameters estimated by techniques developed in this study and simulation results were reproduced measured waveforms.

Tokunaga, Yoshitaka

96

Winds  

NSDL National Science Digital Library

In this problem-based learning (PBL) scenario, students prepare a presentation for investors showing how their fishing company has a significant advantage because it locates upwelling zones and fishing areas using TRMM (Tropical Rainfall Measuring Mission) and other satellite data. Prior to launching the PBL, students learn about wind: the topics of air pressure, coriolis effect, upwelling and the role of differential heating on the atmosphere are explored in classroom demonstrations. Materials required include a beaker, coffee grounds, drinking straw, balloon, flashlight, and turntable. The resource includes teacher background information, glossary, assessment rubric, and an appendix introducing problem-based learning.

97

Millikelvin Lab Machine Shop  

E-print Network

Millikelvin Lab OP105­112 Machine Shop OP132 Resistive Magnet Shop CICC Winding Area Transformers This building is home to the Millikelvin lab, the control room, the resistive magnet and machine shops, the CICC@magnet.fsu.edu (850) 644-4378 (850) 644-0534 2 MACHINE SHOP OP132 Vaughan Williams (A114*) williams

McQuade, D. Tyler

98

Different Virtual Stator Winding Configurations of Open-End Winding Five-Phase PM Machines for Wide Speed Range without Flux Weakening Operation  

E-print Network

. Besides, in order to insure electrical security and to reduce constraints on the Battery Management constant power speed range for a family-car is from 30-40km/h up to 120-150km/h. Electrical machines whose Because of large impact of road transportation on carbon emission, researches on Hybrid Electric Vehicles

Paris-Sud XI, Université de

99

Externally refuelled optical filaments  

NASA Astrophysics Data System (ADS)

Plasma channels produced in air through femtosecond laser filamentation hold great promise for a number of applications, including remote sensing, attosecond physics and spectroscopy, channelling microwaves and lightning protection. In such settings, extended filaments are desirable, yet their longitudinal span is limited by dissipative processes. Although various techniques aiming to prolong this process have been explored, the substantial extension of optical filaments remains a challenge. Here, we experimentally demonstrate that the natural range of a plasma column can be enhanced by at least an order of magnitude when the filament is prudently accompanied by an auxiliary beam. In this arrangement, the secondary low-intensity `dressing' beam propagates linearly and acts as a distributed energy reservoir, continuously refuelling the optical filament. Our approach offers an efficient and viable route towards the generation of extended light strings in air without inducing premature wave collapse or an undesirable beam break-up into multiple filaments.

Scheller, Maik; Mills, Matthew S.; Miri, Mohammad-Ali; Cheng, Weibo; Moloney, Jerome V.; Kolesik, Miroslav; Polynkin, Pavel; Christodoulides, Demetrios N.

2014-04-01

100

A Control of the MMF Space Harmonic Parasitic Torques in the concentrated winding AC Machine Using Skew angle Optimization  

Microsoft Academic Search

In this study, the authors proposed a method of controlling harmonic parasitic torque in concentrated winding induction motor and validated its theory's practicality through the experiment. To control harmonic, the rotor was skewed at an angle and to determine optimum skew angle, three dimensional electromagnetic analysis was performed. The result of analysis demonstrated larger than 20 degree skew angle, which

Hyun Rok Cha; Cheol Ho Yun; Tae Uk Jung; Hyung Mo Kim; Jeong Cheol Kim; Seung Hun Baek; Kwang Heon Kim

2006-01-01

101

Preliminary study on the applicability of semi-geodesic winding in the design and manufacturing of composite towers  

NASA Astrophysics Data System (ADS)

During last twenty years, wind turbine manufacturers took the path of building larger machines to generate more electricity. However, the bigger the size became, the more material was required to support the loads, leading to great weight increases. Larger turbines and higher hub heights also resulted in larger tower base diameters which are limited considering their logistics. In many countries, the limit for transports with special permits maximizes the diameter to 4.5 metres. Considering this fact, the wind turbine market dominated by welded steel shell towers is looking for new structural solutions for their future turbines. Although, composite materials are not used as the structural material in the towers of today's turbines, the demand for larger wind turbines forces engineers to seek for alternative material systems with high specific strength and stiffness ratios to be used in towers. Inspired by the applicability of filament winding in tower production, in the present article we investigated the effect of semi-geodesic winding on the winding angle, thickness, stiffness coefficients and vibration characteristics of filament wound composite conical shells of revolution which simulate wind turbine towers at the structural level. Present study showed that the preset friction applied during semi-geodesic winding is an important design parameter which can be controlled to obtain gradually increasing thickness from tower top to the base of the tower, and favourably alter the dynamic characteristics of the composite towers.

Kayran, A.; ?brahimo?lu, C. S.

2014-12-01

102

Structural design criteria for filament-wound composite shells  

NASA Technical Reports Server (NTRS)

Advanced composite cylinders, manufactured by filament winding, provide a cost effective solution to many present structural applications; however, the compressive performance of filament-wound cylinders is lower than comparable shells fabricated from unidirectional tape. The objective of this study was to determine the cause of this reduction in thin filament-wound cylinders by relating the manufacturing procedures to the quality of the cylinder and to its compressive performance. The experiments on cylinder buckling were complemented by eigenvalue buckling analysis using a detailed geometric model in a finite element analysis. The applicability of classical buckling analyses was also investigated as a design tool.

Hahn, H. T.; Jensen, D. W.; Claus, S. J.; Pai, S. P.; Hipp, P. A.

1994-01-01

103

Filamentation nonlinear optics  

NASA Astrophysics Data System (ADS)

A filamenting femtosecond laser pulse self-stabilizes the intensity fluctuation inside the filament core due to intensity clamping and generates an excellent spatial beam quality inside the core due to self-spatial filtering. The high quality of the core can be sampled by nonlinear processes. A few experimental examples are shown: self-phase modulation, four-wave mixing, third-harmonic generation and waveguide writing in glass.

Chin, S. L.; Théberge, F.; Liu, W.

2007-02-01

104

Wind at Work.  

ERIC Educational Resources Information Center

Describes a project in which students create wind machines to harness the wind's power and do mechanical work. Demonstrates kinetic and potential energy conversions and makes work and power calculations meaningful. Students conduct hands-on investigations with their machines. (DDR)

Adams, Stephen

1998-01-01

105

The Cooling of Electric Machines  

Microsoft Academic Search

The elevation in temperature of the windings of any electric machine due to the internal heat losses is usually the dominating factor in limiting the rating of the machine. This limitation found in the heating, is primarily due to the effects of high temperatures on the various types of insulation used in such machines. The American Institute of Electrical Engineers

George E. Luke

1923-01-01

106

Lightning Protection for Rotating Machines  

Microsoft Academic Search

The high monetary value and low insulation levels of rotating machines make it necessary to employ special protection. A rotating machine can be conceived as a transmission line with distributed constants, the essential difference being that the machine winding is wound back on itself in the form of turns, which may permit high voltage across the turn-to-turn insulation. The installation

G. D. McCann; E. Beck; L. A. Finzi

1944-01-01

107

Evolution of filament barbs.  

NASA Astrophysics Data System (ADS)

We present a selected few cases in which the sense of chirality of filament barbs changed within periods as short as hours. We investigate in detail a quiescent filament on 2003 September 10 and 11. Of its four barbs displaying such changes, only one overlays a small polarity inversion line inside the EUV filament channel (EFC). No magnetic elements with magnitude above the noise level were detected at the endpoints of all barbs. In particular, a pair of barbs first approached toward, and then departed from, each other in Halpha , with the barb endpoints migrating as far as ˜ 10 arcsec. We conclude that the evolution of the barbs was driven by flux emergence and cancellation of small bipolar units at the EFC border.

Liu, R.; Xu, Y.; Wang, H.

108

Aerogel-supported filament  

DOEpatents

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces.

Wuest, Craig R. (Danville, CA); Tillotson, Thomas M. (Tracy, CA); Johnson, III, Coleman V. (Dallas, TX)

1995-01-01

109

Aerogel-supported filament  

DOEpatents

The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces. 6 Figs.

Wuest, C.R.; Tillotson, T.M.; Johnson, C.V. III

1995-05-16

110

Breakup of Liquid Filaments  

E-print Network

and Basaran [11]. Theoretical models for the collapse of a thin filament of a Newtonian liquid (i.e. in which viscosity is independent of shear rate) of finite length, as shown in Fig. 1, have been proposed by Schulkes [10] and Notz and Basaran [11... and Notz and Basaran used combined Lagrangian-Eulerian methods (Galerkin finite element model, G/FEM) to solve the dynamics of in- compressible Newtonian liquid filaments surrounded by an inert ambient fluid, [10] and [11]. Due to computa- tional...

Castrejon-Pita, Alfonso A.; Castrejon-Pita, J.R.; Hutchings, I.M.

2012-01-01

111

Development of a new generation of filament wound composite pressure cylinders  

Microsoft Academic Search

A new generation of composite pressure vessels for large scale market applications has been studied in this work. The vessels consist on a thermoplastic liner wrapped with a filament winding glass fibre reinforced polymer matrix structure. A high density polyethylene (HDPE) was selected as liner and a thermosetting resin used as matrix in the glass reinforced filament wound laminate.The Abaqus

J. C. Velosa; J. P. Nunes; P. J. Antunes; J. F. Silva; A. T. Marques

2009-01-01

112

Interaction of two flapping filaments in a flowing soap film Luoding Zhua)  

E-print Network

the two-dimensional analog of a flag flapping in the wind has much to teach us about biological swimming2Interaction of two flapping filaments in a flowing soap film Luoding Zhua) and Charles S. Peskin of sustained oscillation of the two filaments: parallel flapping and mirror-image clapping, depending

Peskin, Charles S.

113

Periodic Filamentation and Supercontinuum Interference  

NASA Astrophysics Data System (ADS)

In this chapter, supercontinuum (SC) generation and filamentation in BK7 glass were controlled by Fresnel diffraction from a circular aperture or a straight edge. We demonstrated the salient coherent property of multiple SC sources by the periodic filamentation.

Ni, Xiaohui; Alfano, R. R.

114

Power from the Wind  

ERIC Educational Resources Information Center

Wind energy is the fastest-growing renewable energy source in the world. Over the last 20 years, the wind industry has done a very good job of engineering machines, improving materials, and economies of production, and making this energy source a reality. Like all renewable energy forms, wind energy's successful application is site specific. Also,…

Roman, Harry T.

2004-01-01

115

Wind Power Now!  

ERIC Educational Resources Information Center

The government promotes and heavily subsidizes research in nuclear power plants. Federal development of wind power is slow in comparison even though much research with large wind-electric machines has already been conducted. Unless wind power programs are accelerated it will not become a major energy alternative to nuclear power. (MR)

Inglis, David Rittenhouse

1975-01-01

116

ORIGIN OF THE DENSE CORE MASS FUNCTION IN CONTRACTING FILAMENTS  

SciTech Connect

Mass functions of starless dense cores (CMFs) may arise from contraction and dispersal of core-forming filaments. In an illustrative model, a filament contracts radially by self-gravity, increasing the mass of its cores. During this contraction, FUV photoevaporation and ablation by shocks and winds disperse filament gas and limit core growth. The stopping times of core growth are described by a waiting-time distribution. The initial filament column density profile and the resulting CMF each match recent Herschel observations in detail. Then low-mass cores have short growth ages and arise from the innermost filament gas, while massive cores have long growth ages and draw from more extended filament gas. The model fits the initial density profile and CMF best for mean core density 2 Multiplication-Sign 10{sup 4} cm{sup -3} and filament dispersal timescale 0.5 Myr. Then the typical core mass, radius, mean column density, and contraction speed are respectively 0.8 solar masses, 0.06 pc, 6 Multiplication-Sign 10{sup 21} cm{sup -2}, and 0.07 km s{sup -1}, also in accord with observed values.

Myers, Philip C., E-mail: pmyers@cfa.harvard.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2013-02-20

117

Evolving Photospheric Flux Concentrations and Filament Dynamic Changes  

NASA Astrophysics Data System (ADS)

We analyze the role of weak photospheric flux concentrations that evolve in a filament channel, in the triggering of dynamic changes in the shape of a filament. The high polarimetric sensitivity of THEMIS allowed us to detect weak flux concentrations (few Gauss) associated with the filament development. The synoptic instruments (MDI, SOLIS) even if their sensitivity is much less than THEMIS were useful to follow any subsequent strengthening of these flux concentrations after their identification in the THEMIS magnetograms. We found that (1) the northern part of the filament develops an H? barb at the same time that weak minority polarity elements develop near a plage; (2) a section in the southern part of the H? filament gradually disappears and later reforms at the same time that several mixed-polarity magnetic elements appear, then subsequently cancel or spread away from each other. These changes correspond to increases in EUV emission, as observed by TRACE, EIT, and CDS. This suggests that the plasma is temporarily heated along the filament spine. An idealized sequence of force-free models of this filament channel, based on plasma-supporting magnetic dips occurring in the windings of a very weakly twisted flux tube, naturally explains the evolution of its southern part as being due to changes in the topology of the coronal magnetic field as the photospheric flux concentrations evolve.

Schmieder, B.; Aulanier, G.; Mein, P.; López Ariste, A.

2006-11-01

118

Modular Permanent Magnet Machine with Fault Tolerant Capability  

Microsoft Academic Search

Modular permanent magnet machines are gaining popularity due to their simple stator construction and machine winding fabrication. In this paper, a multiphase modular permanent magnet machine is proposed to obtain a robust drive system with the feature of fault tolerant capability. By making use of concentric winding on each module, the stator winding structure is simplified with benefit of less

Wen Ouyang; T.A. Lipo

2009-01-01

119

Wind energy utilization: A bibliography  

NASA Technical Reports Server (NTRS)

Bibliography cites documents published to and including 1974 with abstracts and references, and is indexed by topic, author, organization, title, and keywords. Topics include: Wind Energy Potential and Economic Feasibility, Utilization, Wind Power Plants and Generators, Wind Machines, Wind Data and Properties, Energy Storage, and related topics.

1975-01-01

120

Wind power potential in Oman  

Microsoft Academic Search

Solar energy and wind are likely to play an important role in the future energy generation in Oman. This article assesses wind power cost per kWh of energy produced using four types of wind machines at 27 locations within Oman. These sites cover all regions in Oman. Hourly values of wind speed recorded between 2000 and 2009, in most cases,

A. H. Al-Badi

2011-01-01

121

Interplanetary shocks preceded by solar filament eruptions  

NASA Technical Reports Server (NTRS)

The solar and interplanetary characteristics of six interplanetary shock and energetic particle events associated with the eruptions of solar filaments lying outside active regions are discussed. The events are characterized by the familiar double-ribbon H-alpha brightenings observed with large flares, but only very weak soft X-ray and microwave bursts. Both impulsive phases and metric type II bursts are absent in all six events. The energetic particles observed near the earth appear to be accelerated predominantly in the interplanetary shocks. The interplanetary shock speeds are lower and the longitudinal extents considerably less than those of flare-associated shocks. Three of the events were associated with unusual enhancements of singly-ionized helium in the solar wind following the shocks. These enhancements appear to be direct detections of the cool filament material expelled from the corona. It is suggested that these events are part of a spectrum of solar eruptive events which include both weaker events and the large flares. Despite their unimpressive and unreported solar signatures, the quiescent filament eruptions can result in substantial space and geophysical disturbances.

Cane, H. V.; Kahler, S. W.; Sheeley, N. R., Jr.

1986-01-01

122

Protein machines and self assembly in muscle organization  

NASA Technical Reports Server (NTRS)

The remarkable order of striated muscle is the result of a complex series of protein interactions at different levels of organization. Within muscle, the thick filament and its major protein myosin are classical examples of functioning protein machines. Our understanding of the structure and assembly of thick filaments and their organization into the regular arrays of the A-band has recently been enhanced by the application of biochemical, genetic, and structural approaches. Detailed studies of the thick filament backbone have shown that the myosins are organized into a tubular structure. Additional protein machines and specific myosin rod sequences have been identified that play significant roles in thick filament structure, assembly, and organization. These include intrinsic filament components, cross-linking molecules of the M-band and constituents of the membrane-cytoskeleton system. Muscle organization is directed by the multistep actions of protein machines that take advantage of well-established self-assembly relationships. Copyright 1999 John Wiley & Sons, Inc.

Barral, J. M.; Epstein, H. F.

1999-01-01

123

Mean Machines.  

ERIC Educational Resources Information Center

Suggests scales as alternative representations of numerical concepts and operations that can be used as arithmetic-mean machines, adding machines, multiplication machines, and geometric-mean machines. (ASK)

Flores, Alfinio

1998-01-01

124

Chaperonin filaments: The archael cytoskeleton  

SciTech Connect

Chaperonins are multi-subunit double-ring complexed composed of 60-kDa proteins that are believed to mediate protein folding in vivo. The chaperonins in the hyperthermophilic archaeon Sulfolobus shibatae are composed of the organism`s two most abundant proteins, which represent 4% of its total protein and have an intracellular concentration of {ge} 3.0 mg/ml. At concentrations of 1.0 mg/ml, purified chaperonin proteins aggregate to form ordered filaments. Filament formation, which requires Mg{sup ++} and nucleotide binding (not hydrolysis), occurs at physiological temperatures under conditions suggesting filaments may exist in vivo. If the estimated 4,600 chaperonins per cell, formed filaments in vivo, they could create a matrix of filaments that would span the diameter of an average S. shibatae cell 100 times. Direct observations of unfixed, minimally treated cells by intermediate voltage electron microscopy (300 kV) revealed an intracellular network of filaments that resembles chaperonin filaments produced in vitro. The hypothesis that the intracellular network contains chaperonins is supported by immunogold analyses. The authors propose that chaperonin activity may be regulated in vivo by filament formation and that chaperonin filaments may serve a cytoskeleton-like function in archaea and perhaps in other prokaryotes.

Trent, J.D.; Kagawa, H.K.; Yaoi, Takuro; Olle, E.; Zaluzec, N.J.

1997-08-01

125

Magnetic vortex filament flows  

SciTech Connect

We exhibit a variational approach to study the magnetic flow associated with a Killing magnetic field in dimension 3. In this context, the solutions of the Lorentz force equation are viewed as Kirchhoff elastic rods and conversely. This provides an amazing connection between two apparently unrelated physical models and, in particular, it ties the classical elastic theory with the Hall effect. Then, these magnetic flows can be regarded as vortex filament flows within the localized induction approximation. The Hasimoto transformation can be used to see the magnetic trajectories as solutions of the cubic nonlinear Schroedinger equation showing the solitonic nature of those.

Barros, Manuel; Cabrerizo, Jose L.; Fernandez, Manuel; Romero, Alfonso [Departamento de Geometria y Topologia, Facultad de Ciencias, Universidad de Granada, 18071-Granada (Spain); Departamento de Geometria y Topologia, Facultad de Matematicas, Universidad de Sevilla, 41012-Sevilla (Spain); Departamento de Geometria y Topologia, Facultad de Ciencias, Universidad de Granada, 18071-Granada (Spain)

2007-08-15

126

Analytical expressions for maximum wind turbine average power in a Rayleigh wind regime  

SciTech Connect

Average or expectation values for annual power of a wind turbine in a Rayleigh wind regime are calculated and plotted as a function of cut-out wind speed. This wind speed is expressed in multiples of the annual average wind speed at the turbine installation site. To provide a common basis for comparison of all real and imagined turbines, the Rayleigh-Betz wind machine is postulated. This machine is an ideal wind machine operating with the ideal Betz power coefficient of 0.593 in a Rayleigh probability wind regime. All other average annual powers are expressed in fractions of that power. Cases considered include: (1) an ideal machine with finite power and finite cutout speed, (2) real machines operating in variable speed mode at their maximum power coefficient, and (3) real machines operating at constant speed.

Carlin, P.W.

1996-12-01

127

Wind energy : energy from moving air  

NSDL National Science Digital Library

This resource focuses on the renewable resource of wind energy. This brief overview of wind energy explores how moving air is managed when it is formed. This resource will address such topics as (1) What is Wind?, (2) The History of Wind, (3) Windmill Mechanics, (4) Wind Machines Today, (5) Types of Windmills, (6) Wind Power Plants, (7) Wind Resources, (8) Wind Production, (9) Wind Energy Economics, (10) Wind and the Environment, and (11) the Future of Wind. Copyright 2005 International Technology Education Association

US Department of Energy (DOE). Energy Information Administration (EIA)

2003-01-01

128

Quantification of Processing Effects on Filament Wound Pressure Vessels  

NASA Technical Reports Server (NTRS)

A computational simulation procedure is described which is designed specifically for the modeling and analysis of filament wound pressure vessels. Cylindrical vessels with spherical or elliptical end caps can be generated automatically. End caps other than spherical or elliptical may be modeled by varying circular sections along the x-axis according to the C C! end cap shape. The finite element model generated is composed of plate type quadrilateral shell elements on the entire vessel surface. This computational procedure can also be sued to generate grid, connectivity and material cards (bulk data) for component parts of a larger model. These bulk data are assigned to a user designated file for finite element structural/stress analysis of composite pressure vessels. The procedure accommodates filament would pressure vessels of all types of shells-of-revolution. It has provisions to readily evaluate initial stresses due to pretension in the winding filaments and residual stresses due to cure temperature.

Aiello, Robert A.; Chamis, Christos C.

1999-01-01

129

Quantification of Processing Effects on Filament Wound Pressure Vessels. Revision  

NASA Technical Reports Server (NTRS)

A computational simulation procedure is described which is designed specifically for the modeling and analysis of filament wound pressure vessels. Cylindrical vessels with spherical or elliptical end caps can be generated automatically. End caps other than spherical or elliptical may be modeled by varying circular sections along the x-axis according to the end cap shape. The finite element model generated is composed of plate type quadrilateral shell elements on the entire vessel surface. This computational procedure can also be used to generate grid, connectivity and material cards (bulk data) for component parts of a larger model. These bulk data are assigned to a user designated file for finite element structural/stress analysis of composite pressure vessels. The procedure accommodates filament wound pressure vessels of all types of shells-of -revolution. It has provisions to readily evaluate initial stresses due to pretension in the winding filaments and residual stresses due to cure temperature.

Aiello, Robert A.; Chamis, Christos C.

2002-01-01

130

Dynamics of contracting viscoelastic filaments  

NASA Astrophysics Data System (ADS)

Satellite drops are detrimental to many industrial applications involving the formation of viscoelastic drops including inkjet printing, DNA microarraying, and printing of flexible solar cells. The precursor to these satellite drops is a slender liquid filament that connects an about-to-form drop to the rest of the liquid in the nozzle. Once a filament is formed, it contracts due to surface tension. A filament may undergo further breakup during recoil. Whereas the contraction of Newtonian filaments in a passive ambient fluid is well understood (Schulkes 1996 and Notz and Basaran 2004), the contraction dynamics of viscoelastic filaments remains largely unexplored and is addressed in this presentation. Here the filament shape is idealized as an axisymmetric fluid cylinder terminated by hemispherical end-caps, and the conformation tensor formalism (Pasquali & Scriven 2002) is used to model the viscoelasticity. The dynamics of contracting filaments are then analyzed by means of both a well-benchmarked two-dimensional finite element algorithm (Notz et al. 2001, Chen et al. 2002) and a one-dimensional slender-jet algorithm (Padgett et al. 1996). Regions of the parameter space are identified where recoiling filaments give rise to either a single satellite drop or multiple satellites.

Harris, Michael; Appathurai, Santosh; Bhat, Pradeep; Basaran, Osman

2009-11-01

131

Experimental superconducting unipolar machine  

Microsoft Academic Search

Basic design and preliminary test results of an experimental superconducting unipolar machine are presented. The inductor is a superconducting axisymmetric coil placed in a helium tank. The inductor winding consists of twisted multifiber Nb-Ti superconductors with copper matrix, and consists of series-connected sections having different diameters of the superconducting cable. Modeling considerations for extrapolating results to larger systems are discussed.

B. L. Alievskii; A. M. Oktiabrskii; V. L. Orlov

1979-01-01

132

The bearingless electrical machine  

NASA Astrophysics Data System (ADS)

Electromagnetic bearings allow the suspension of solids. For rotary applications, the most important physical effect is the force of a magnetic circuit to a high permeable armature, called the MAXWELL force. Contrary to the commonly used MAXWELL bearings, the bearingless electrical machine will take advantage of the reaction force of a conductor carrying a current in a magnetic field. This kind of force, called Lorentz force, generates the torque in direct current, asynchronous and synchronous machines. The magnetic field, which already exists in electrical machines and helps to build up the torque, can also be used for the suspension of the rotor. Besides the normal winding of the stator, a special winding was added, which generates forces for levitation. So a radial bearing, which is integrated directly in the active part of the machine, and the motor use the laminated core simultaneously. The winding was constructed for the levitating forces in a special way so that commercially available standard ac inverters for drives can be used. Besides wholly magnetic suspended machines, there is a wide range of applications for normal drives with ball bearings. Resonances of the rotor, especially critical speeds, can be damped actively.

Bichsel, J.

1992-05-01

133

The Bearingless Electrical Machine  

NASA Technical Reports Server (NTRS)

Electromagnetic bearings allow the suspension of solids. For rotary applications, the most important physical effect is the force of a magnetic circuit to a high permeable armature, called the MAXWELL force. Contrary to the commonly used MAXWELL bearings, the bearingless electrical machine will take advantage of the reaction force of a conductor carrying a current in a magnetic field. This kind of force, called Lorentz force, generates the torque in direct current, asynchronous and synchronous machines. The magnetic field, which already exists in electrical machines and helps to build up the torque, can also be used for the suspension of the rotor. Besides the normal winding of the stator, a special winding was added, which generates forces for levitation. So a radial bearing, which is integrated directly in the active part of the machine, and the motor use the laminated core simultaneously. The winding was constructed for the levitating forces in a special way so that commercially available standard ac inverters for drives can be used. Besides wholly magnetic suspended machines, there is a wide range of applications for normal drives with ball bearings. Resonances of the rotor, especially critical speeds, can be damped actively.

Bichsel, J.

1992-01-01

134

Wind Energy Systems.  

ERIC Educational Resources Information Center

During the 1920s and 1930s, millions of wind energy systems were used on farms and other locations far from utility lines. However, with passage of the Rural Electrification Act in 1939, cheap electricity was brought to rural areas. After that, the use of wind machines dramatically declined. Recently, the rapid rise in fuel prices has led to a…

Conservation and Renewable Energy Inquiry and Referral Service (DOE), Silver Spring, MD.

135

Purification of native myosin filaments from muscle.  

PubMed Central

Analysis of the structure and function of native thick (myosin-containing) filaments of muscle has been hampered in the past by the difficulty of obtaining a pure preparation. We have developed a simple method for purifying native myosin filaments from muscle filament suspensions. The method involves severing thin (actin-containing) filaments into short segments using a Ca(2+)-insensitive fragment of gelsolin, followed by differential centrifugation to purify the thick filaments. By gel electrophoresis, the purified thick filaments show myosin heavy and light chains together with nonmyosin thick filament components. Contamination with actin is below 3.5%. Electron microscopy demonstrates intact thick filaments, with helical cross-bridge order preserved, and essentially complete removal of thin filaments. The method has been developed for striated muscles but can also be used in a modified form to remove contaminating thin filaments from native smooth muscle myofibrils. Such preparations should be useful for thick filament structural and biochemical studies. PMID:11606293

Hidalgo, C; Padrón, R; Horowitz, R; Zhao, F Q; Craig, R

2001-01-01

136

Intermediate filaments: a historical perspective.  

PubMed

Intracellular protein filaments intermediate in size between actin microfilaments and microtubules are composed of a surprising variety of tissue specific proteins commonly interconnected with other filamentous systems for mechanical stability and decorated by a variety of proteins that provide specialized functions. The sequence conservation of the coiled-coil, alpha-helical structure responsible for polymerization into individual 10 nm filaments defines the classification of intermediate filament proteins into a large gene family. Individual filaments further assemble into bundles and branched cytoskeletons visible in the light microscope. However, it is the diversity of the variable terminal domains that likely contributes most to different functions. The search for the functions of intermediate filament proteins has led to discoveries of roles in diseases of the skin, heart, muscle, liver, brain, adipose tissues and even premature aging. The diversity of uses of intermediate filaments as structural elements and scaffolds for organizing the distribution of decorating molecules contrasts with other cytoskeletal elements. This review is an attempt to provide some recollection of how such a diverse field emerged and changed over about 30 years. PMID:17493611

Oshima, Robert G

2007-06-10

137

Wet Winding Improves Coil Encapsulation  

NASA Technical Reports Server (NTRS)

Wet-winding process encapsulates electrical coils more uniformily than conventional processes. Process requires no vacuum pump and adapts easily to existing winding machines. Encapsulant applied to each layer of wire as soon as added to coil. Wet-winding process eliminates voids, giving more uniformly encapsulated coil.

Hill, A. J.

1987-01-01

138

Leonid meteoroids from different filaments  

NASA Astrophysics Data System (ADS)

The perihelion passage of Comet 55P/Tempel-Tuttle in 1998 was followed by several strong storms and other periods of enhanced activity between 1998 and 2009. Double-station video data were collected in 1999, 2000, 2001, 2006, and 2009. This sample of several hundreds of meteors is covering filaments of different age. We investigated the atmospheric trajectories, especially the beginning heights of the meteors. The beginning height depends on the meteor photometric mass. It was found that the slope of this dependence is different for each filament. Higher slope means more fragile particles. It seems that there is a correlation between the age of the filament and the slope of the above-mentioned dependence: the older filaments show a higher slope than the younger ones.

Koten, P.

2012-01-01

139

Plasticity of Intermediate Filament Subunits  

E-print Network

Intermediate filaments (IFs) assembled in vitro from recombinantly expressed proteins have a diameter of 8–12 nm and can reach several micrometers in length. IFs assemble from a soluble pool of subunits, tetramers in the ...

Kirmse, Robert

140

Secondary ELM Filaments in NSTX  

SciTech Connect

Filamentary structures are observed in the scrape-off layer of the National Spherical Torus Experime05nt during ELMs. While the primary filaments correspond to a direct result of the ELM event, the 'secondary' filaments which occur generally later but still within 1 ms of the ELM onset are observed to have the same characteristics as inter-ELM filaments (or blobs): poloidal auto-correlation lengths of similar to 4 cm, broadband frequency and poloidal wave number spectra and radial velocities of 1-2 km/s. At the same time, no MHD modes are observed during the phase in which secondary filaments are present. (C) 2009 Elsevier B.V. All rights reserved.

Maqueda, R. J. [Nova Photonics, Princeton, NJ; Maingi, Rajesh [ORNL; Ahn, J W [University of California, San Diego; NSTX Team, [Multiple Institutions

2009-01-01

141

Collisions of Vortex Filament Pairs  

NASA Astrophysics Data System (ADS)

We consider the problem of collisions of vortex filaments for a model introduced by Klein et al. (J Fluid Mech 288:201-248, 1995) and Zakharov (Sov Phys Usp 31(7):672-674, 1988, Lect. Notes Phys 536:369-385, 1999) to describe the interaction of almost parallel vortex filaments in three-dimensional fluids. Since the results of Crow (AIAA J 8:2172-2179, 1970) examples of collisions are searched as perturbations of antiparallel translating pairs of filaments, with initial perturbations related to the unstable mode of the linearized problem; most results are numerical calculations. In this article, we first consider a related model for the evolution of pairs of filaments, and we display another type of initial perturbation leading to collision in finite time. Moreover, we give numerical evidence that it also leads to collision through the initial model. We finally study the self-similar solutions of the model.

Banica, Valeria; Faou, Erwan; Miot, Evelyne

2014-12-01

142

Centromeres of filamentous fungi  

PubMed Central

How centromeres are assembled and maintained remains one of the fundamental questions in cell biology. Over the past 20 years the idea of centromeres as precise genetic loci has been replaced by the realization that it is predominantly the protein complement that defines centromere localization and function. Thus, placement and maintenance of centromeres are excellent examples of epigenetic phenomena in the strict sense. In contrast, the highly derived “point centromeres” of the budding yeast Saccharomyces cerevisiae and its close relatives are counterexamples for this general principle of centromere maintenance. While we have learned much in the past decade, it remains unclear if mechanisms for epigenetic centromere placement and maintenance are shared amongst various groups of organisms. For that reason it seems prudent to examine species from many different phylogenetic groups with the aim to extract comparative information that will yield a more complete picture of cell division in all eukaryotes. This review addresses what has been learned by studying the centromeres of filamentous fungi, a large, heterogeneous group of organisms that includes important plant, animal and human pathogens, saprobes and symbionts that fulfill essential roles in the biosphere, as well as a growing number of taxa that have become indispensable for industrial use. PMID:22752455

Smith, Kristina M.; Galazka, Jonathan M.; Phatale, Pallavi A.; Connolly, Lanelle R.; Freitag, Michael

2012-01-01

143

Electron emitting filaments for electron discharge devices  

DOEpatents

Electrons are copiously emitted by a device comprising a loop-shaped filament made of lanthanum hexaboride. The filament is directly heated by an electrical current produced along the filament by a power supply connected to the terminal legs of the filament. To produce a filament, a diamond saw or the like is used to cut a slice from a bar made of lanthanum hexaboride. The diamond saw is then used to cut the slice into the shape of a loop which may be generally rectangular, U-shaped, hairpin-shaped, zigzag-shaped, or generally circular. The filaments provide high electron emission at a relatively low operating temperature, such as 1600/sup 0/C. To achieve uniform heating, the filament is formed with a cross section which is tapered between the opposite ends of the filament to compensate for nonuniform current distribution along the filament due to the emission of electrons from the filament.

Leung, K.N.; Pincosy, P.A.; Ehlers, K.W.

1983-06-10

144

Electron emitting filaments for electron discharge devices  

DOEpatents

Electrons are copiously emitted by a device comprising a loop-shaped filament made of lanthanum hexaboride. The filament is directly heated by an electrical current produced along the filament by a power supply connected to the terminal legs of the filament. To produce a filament, a diamond saw or the like is used to cut a slice from a bar made of lanthanum hexaboride. The diamond saw is then used to cut the slice into the shape of a loop which may be generally rectangular, U-shaped, hairpin-shaped, zigzag-shaped, or generally circular. The filaments provide high electron emission at a relatively low operating temperature, such as 1600.degree. C. To achieve uniform heating, the filament is formed with a cross section which is tapered between the opposite ends of the filament to compensate for non-uniform current distribution along the filament due to the emission of electrons from the filament.

Leung, Ka-Ngo (Hercules, CA); Pincosy, Philip A. (Oakland, CA); Ehlers, Kenneth W. (Alamo, CA)

1988-01-01

145

Machine Shop Grinding Machines.  

ERIC Educational Resources Information Center

This curriculum manual is one in a series of machine shop curriculum manuals intended for use in full-time secondary and postsecondary classes, as well as part-time adult classes. The curriculum can also be adapted to open-entry, open-exit programs. Its purpose is to equip students with basic knowledge and skills that will enable them to enter the…

Dunn, James

146

Analysis and Steady-State Behavior of an Optimized AC Converter Machine  

Microsoft Academic Search

AC machines presently designed to operate from a solid state power converter retain a sinusoidal winding distribution even though such machines were originally intended only for operation with sinusoidal rather than rectangular power supplies. This paper describes a unique type of concentrated winding machine in which the winding distribution is intentionally rectangular to better accomodate the rectangular waveforms of conventional

F. X. Wang; T.A. Lipo

1983-01-01

147

Wind energy conversion system  

DOEpatents

The wind energy conversion system includes a wind machine having a propeller connected to a generator of electric power, the propeller rotating the generator in response to force of an incident wind. The generator converts the power of the wind to electric power for use by an electric load. Circuitry for varying the duty factor of the generator output power is connected between the generator and the load to thereby alter a loading of the generator and the propeller by the electric load. Wind speed is sensed electro-optically to provide data of wind speed upwind of the propeller, to thereby permit tip speed ratio circuitry to operate the power control circuitry and thereby optimize the tip speed ratio by varying the loading of the propeller. Accordingly, the efficiency of the wind energy conversion system is maximized.

Longrigg, Paul (Golden, CO)

1987-01-01

148

Kinematics of Filaments in Perseus and Serpens: Testing Filament Formation  

NASA Astrophysics Data System (ADS)

The CARMA Large Area Star formation Survey (CLASSy) used the N2H+molecule to trace the kinematics cool, dense filaments in Perseus and Serpens. A number of these filaments showed velocity gradients perpendicular to the long axis of filaments which were interpreted as gravity induced inflow of material from a dense post-shock layer in a turbulent cloud based on simulations (Chen and Ostriker 2014; Mundy et al 2014). These gradients were not as visible in HCN and HCO+, which were also mapped by CLASSy, due to the higher optical depth in these J=1-0 transitions. In this poster, we present the initial observations of the H13CO+ and HNC transitions toward a number of target filaments from the CLASSy. The goals of the observations are to confirm the kinematics seen in N2H+, hence confirming that the observed gradients are not due to a chemical effect in N2H+, and to see if these molecular lines can provide additional information about the kinematics of the filaments.

Mundy, Lee G.; Storm, Shaye; Rizzo, Maxime; Looney, Leslie; Chen, Che-Yu; Ostriker, Eve C.; Lee, Katherine I.; Classy Team

2015-01-01

149

Kinematics of Filaments in Perseus and Serpens: Testing Filament Formation  

NASA Astrophysics Data System (ADS)

The CARMA Large Area Star formation Survey (CLASSy) used the N2H+ molecule to trace the kinematics cool, dense filaments in Perseus and Serpens. A number of these filaments showed velocity gradients perpendicular to the long axis of filaments which were interpreted as gravity induced inflow of material from a dense post-shock layer in a turbulent cloud based on simulations (Chen and Ostriker 2014; Mundy et al 2014). These gradients were not as visible in HCN and HCO+, which were also mapped by CLASSy, due to the higher optical depth in these J=1-0 transitions. In this poster, we present the initial observations of the H13CO+ and HNC transitions toward a number of target filaments from the CLASSy. The goals of the observations are to confirm the kinematics seen in N2H+, hence confirming that the observed gradients are not due to a chemical effect in N2H+, and to see if these molecular lines can provide additional information about the kinematics of the filaments.

CLASSy Team

2015-01-01

150

The circulation dynamics associated with a northern Benguela upwelling filament during October 2010  

NASA Astrophysics Data System (ADS)

Upwelling filaments, a common feature in all the major upwelling systems, are also regularly observed in the Benguela upwelling system and are thought to provide an effective mechanism for the exchange of matter between the shelf and the open ocean. The mesoscale dynamics of a northern Benguela upwelling filament located at approximately 18.5°S were examined and the associated transport was quantified. The development of the filament was tracked using optimal interpolated SST satellite data and two transects were consequently sampled across the feature using a towed undulating CTD (ScanFish). Additional hydrographic, nutrient and biological parameters were investigated at several stations along each transect. Following 7 days of strong upwelling favorable winds, sampling coincided with a period of relative wind relaxation and the filament was presumably in a decaying state. The basic mesoscale structure of the investigated filament corresponded well to what had previously been described for filaments from other eastern boundary current systems. The cross-shore transport associated with the filament was found to be significantly greater than the integrated Ekman transport in the region. With the combination of the high resolution dataset and a MOM-4 ecosystem model the complex mesoscale flow field associated with the feature could be observed and the counterbalancing onshore transport, associated with subsurface dipole eddies, was revealed within the filament. The results further suggest that an interaction between the offshore bending of flow at the Angola-Benguela Front (ABF), the detachment of the strong poleward flow from the coast as the thermal front meanders and the observed dipole eddies may be driving filament occurrence in the region off Cape Frio.

Muller, Annethea A.; Mohrholz, Volker; Schmidt, Martin

2013-07-01

151

Droplets engulfing on a filament  

NASA Astrophysics Data System (ADS)

Two immiscible droplets wetting on a filament may assume engulfing, partial-engulfing, or non-engulfing morphology that depends on the wetting behavior and geometries of the resulting droplet-on-filament system. This paper studies the wetting behavior of two immiscible droplets contacting and sitting symmetrically on a straight filament. A set of ordinary differential equations (ODEs) is formulated for determining the wetting morphology of the droplet-on-filament system. In the limiting case of engulfing or non-engulfing, the morphology of the droplet-on-filament system is determined in explicit form. In the case of partial-engulfing, surface finite element method is further employed for determining the wetting morphology, surface energy, and internal pressures of droplets of the system. Numerical scaling study is performed to explore their dependencies upon the wetting properties and geometries of the system. The study can be applicable for analysis and design of textiles with tailorable wetting properties and development of novel multifunctional fibrous materials for environmental protection such as oil-spill sorption, etc.

Wu, Xiang-Fa; Yu, Meng; Zhou, Zhengping; Bedarkar, Amol; Zhao, Youhao

2014-03-01

152

Quantification of biopolymer filament structure.  

PubMed

The quantitative analysis of a polymer network is important for understanding its role in biological function. We developed a Matlab program to recognize and segment filaments in a 2-D image, and measure and describe the structure. Our algorithm improved the speed of the Lichtenstein Fiberscore segmentation algorithm by using matrix convolutions, compared filament length by the algorithms of Kulpa, Lichtenstein, and Kimura, and measured the number of branchpoints and Euler number. A user interface was added to easily manipulate algorithm parameters, select images, and visualize results. We used the program to compare the DNA biopolymer network of cystic fibrosis (CF) sputum with mucus from patients without respiratory problems. We also examined an image of fibrin. The images were taken with a laser scanning confocal microscope after staining the specimens with Yo-Yo-1. Computation using matrix convolutions reduced the execution time (Pentium III) of a 512 x 512 TIF image from 18 min to 15s. The Kimura length estimation appeared best at describing filament length because it varied least with filament orientation. The image of CF sputum showed increased filament length, more branchpoints, and more negative Euler number compared to the normal sample. These quantitative descriptions of the network can be correlated to material, mechanical, diffusion, or flow properties, physiological processes, or therapy. PMID:15961231

Shah, Samir A; Santago, Pete; Rubin, Bruce K

2005-10-01

153

Effect of Number of Phases on Losses in Conducting Sleeves of Surface PM Machine Rotors Equipped With Fractional-Slot Concentrated Windings  

Microsoft Academic Search

High-speed machines with a solid rotor or a high- strength retaining sleeve could offer design and performance advantages. For a specific application, if the use of a high-strength nonmagnetic metallic retaining sleeve is more advantageous than a nonmetallic (e.g., carbon fiber) one, one needs to evaluate the eddy-current losses due to armature reaction space and time harmonics and\\/or tooth ripple,

Ayman M. EL-Refaie; Manoj R. Shah; Ronghai Qu; John M. Kern

2008-01-01

154

Security assessment of power systems including energy storage and with the integration of wind energy. Progress report, October 1, 1979-December 31, 1979  

SciTech Connect

Progress in wind energy studies is reported. During this quarter two areas were pursued: wind turbulence models and their effect on unsteady shaft torque of horizontal machines; and reduced order aerodynamic models of wind machines. (LCL)

Carroll, D P; Krause, P C

1980-01-01

155

Coiling of a viscous filament  

NASA Astrophysics Data System (ADS)

A classic demonstration of fluid buckling is a daily occurence at the breakfast table, where a continuous stream of viscous fluid (honey) is often poured onto a flat surface (toast) from a sufficient height. The thin fluid filament quickly settles into a steady state; near the surface it bends into a helical shape while simultaneously rotating about the vertical and is laid out in a regular coil. This behavior is reminiscent of the coiling of a falling flexible rope. We derive a simple scaling law that predicts the coiling frequency in terms of the filament radius and the flow rate. We also verify this scaling law with the results of experiments.

Samuel, A. D. T.; Ryu, W. S.; Mahadevan, L.

1997-11-01

156

Kid Machine  

NSDL National Science Digital Library

This activity is on page 3 (continued on page 2) of the pdf, part of the Simple Machines Discovery Box. In this fun activity, learners "create" a complex machine by simulating the parts in action. Learners move their bodies and make sounds as if they are individual parts of a moving machine. Then learners discover what happens when part of a machine is broken and problem solve ways to fix it.

2012-06-26

157

Simple Machines  

NSDL National Science Digital Library

This is an online activity about simple machines. Learners will try their hand at putting these amazing devices to work. They will use several simple machines to help "build" a tree house. This is an excellent activity to demonstrate how science - in particular, simple machines - are at work in our everyday lives.

Cosi

2000-01-01

158

Electrostatic Machines  

NSDL National Science Digital Library

This website from Antonio Carlos M. De Queiroz, an associate professor at the Federal University of Rio de Janeiro, illustrates a number of different electrostatic machines. The site includes details and images of machines built by the professor as well as many other historical machines of this type. Some information is also available in Portugese.

De Queiroz, Antonio C.

2011-07-13

159

Simple Machines  

NSDL National Science Digital Library

This is a lesson about simple machines and how they relate to robots. Learners will gain an understanding of simple machines and how they may be used in our everyday lives. Students will also have an opportunity to design a Rube Goldberg Machine of their own. This is lesson 10 of 16 in the MarsBots learning module.

160

Predictive control of wind energy conversion system  

Microsoft Academic Search

Grid connected wind energy conversion systems (WECS) present interesting control demands, due to the intrinsic nonlinear characteristics of windmills and electric generators. In this paper a predictive control strategy for doubly fed induction machine is proposed. The doubly fed induction machine is used in generating mode for large-scale grid-connected variable speed wind turbines. In order to control the active and

M. Bayat; H. Kazemi Karegar

2009-01-01

161

Studies on the dynamics of limited filaments  

E-print Network

A study on the dynamics of filaments in the presence of a diagnostic, conductive limiter is presented. Plasma filaments are coherent structures present in many fusion devices and transport a significant amount of particles ...

Bonde, Jeffrey David

2010-01-01

162

Numerical simulation of vortex breakdown by the vortex-filament method  

NASA Technical Reports Server (NTRS)

The vortex filament method was applied to the simulation of vortex breakdown. The principal vortex region was represented by multiple filaments, and an axial velocity component was induced by a spiral winding of the filaments. First, an accuracy check was performed for a cylindrical swirling flow with simple analytical expressions for the axial and theta velocities. The result suggests that the flow field is simulated to any accuracy by increasing the number of filaments. Second, an axisymmetric type vortex breakdown was simulated, with experimental data serving as upstream conditions. The calculated axial and theta velocity contours show the breakdown of the vortex, including a rapid change in the vortex core, followed axially by a recovery zone and then a second breakdown. When three dimensional initial data are used the second breakdown appears to be of the spiral type in correspondence with experimental observations. The present method is easily used to simulate other types of vortex breakdown or other vortex flows with axial velocity.

Nakamura, Y.; Leonard, A.; Spalart, P. R.

1983-01-01

163

Theory of Crosslinked Bundles of Helical Filaments: Intrinsic Torques in Self-Limiting Biopolymer Assemblies  

E-print Network

Inspired by the complex influence of the globular crosslinking proteins on the formation of biofilament bundles in living organisms, we study and analyze a theoretical model for the structure and thermodynamics of bundles of helical filaments assembled in the presence of crosslinking molecules. The helical structure of filaments, a universal feature of biopolymers such as filamentous actin, is shown to generically frustrate the geometry of crosslinking between the "grooves" of two neighboring filaments. We develop a coarse-grained model to investigate the interplay between the geometry of binding and mechanics of both linker and filament distortion, and we show that crosslinking in parallel bundles of helical filaments generates {\\it intrinsic torques}, of the type that tend to wind bundle superhelically about its central axis. Crosslinking mediates a non-linear competition between the preference for bundle twist and the size-dependent mechanical cost of filament bending, which in turn gives rise to feedback between the global twist of self-assembled bundles and their lateral size. Finally, we demonstrate that above a critical density of bound crosslinkers, twisted bundles form with a thermodynamically preferred radius that, in turn, increases with a further increase in crosslinking bonds. We identify the {\\it stiffness} of crosslinking bonds as a key parameter governing the sensitivity of bundle structure and assembly to the availability and affinity of crosslinkers.

Claus Heussinger; Gregory M. Grason

2011-04-27

164

Wind Energy Conversion Using a Self-Excited Induction Generator  

Microsoft Academic Search

A wind energy conversion scheme using an induction machine driven by a variable speed wind turbine is described. Excitation control has been obtained by employing a single value capacitor and thyristor controlled inductor. Wind speed cube law is proposed to be followed in loading the induction machine for maximising energy conversion. Performance characteristics of the generation scheme have been evaluated

G. Raina; O. P. Malik

1983-01-01

165

The Fluid Foil: The Seventh Simple Machine  

ERIC Educational Resources Information Center

A simple machine does one of two things: create a mechanical advantage (lever) or change the direction of an applied force (pulley). Fluid foils are unique among simple machines because they not only change the direction of an applied force (wheel and axle); they convert fluid energy into mechanical energy (wind and Kaplan turbines) or vice versa,…

Mitts, Charles R.

2012-01-01

166

: Helmholtz machine estimation .  

E-print Network

: Helmholtz machine density estimation . . : . . . (supervised learning) , (active learning) (query learning) [1, 3]. . (unsupervised learning), . , [5]. . Helmholtz machine , . Helmholtz machine : Helmholtz machine [2] . Helmholtz machine (generative network) (recognition network) . , , . Helmholtz machine (self

167

Kicking Machine  

NSDL National Science Digital Library

In this design challenge activity, learners build a machine that kicks a Ping-Pong ball into a cup lying on its side 12 inches away. Learners use a pendulum, a rubber band, or a combination of the two to do this and test the accuracy of their machines by shooting a Ping-Pong ball into a cup. Educators can use this activity to demonstrate simple machines and kinetic/potential energy. This activity can be followed up with "Extreme Kicking Machine" which adds an even greater challenge into the mix.

2012-08-20

168

Design, fabrication, and test of a composite material wind turbine rotor blade  

NASA Technical Reports Server (NTRS)

The aerodynamic design, structural design, fabrication, and structural testing is described for a 60 foot long filament wound, fiberglass/epoxy resin matrix wind turbine rotor blade for a 125 foot diameter, 100 kW wind energy conversion system. One blade was fabricated which met all aerodynamic shape requirements and was structurally capable of operating under all specified design conditions. The feasibility of filament winding large rotor blades was demonstrated.

Griffee, D. G., Jr.; Gustafson, R. E.; More, E. R.

1977-01-01

169

Lighting the universe with filaments.  

PubMed

The first stars in the universe form when chemically pristine gas heats as it falls into dark-matter potential wells, cools radiatively because of the formation of molecular hydrogen, and becomes self-gravitating. Using supercomputer simulations, we demonstrated that the stars' properties depend critically on the currently unknown nature of the dark matter. If the dark-matter particles have intrinsic velocities that wipe out small-scale structure, then the first stars form in filaments with lengths on the order of the free-streaming scale, which can be approximately 10(20) meters (approximately 3 kiloparsecs, corresponding to a baryonic mass of approximately 10(7) solar masses) for realistic "warm dark matter" candidates. Fragmentation of the filaments forms stars with a range of masses, which may explain the observed peculiar element abundance pattern of extremely metal-poor stars, whereas coalescence of fragments and stars during the filament's ultimate collapse may seed the supermassive black holes that lurk in the centers of most massive galaxies. PMID:17872439

Gao, Liang; Theuns, Tom

2007-09-14

170

Rotating electric machine with fluid supported parts  

DOEpatents

A rotating electric machine in which the armature winding thereof and other parts are supported by a liquid to withstand the mechanical stresses applied during transient overloads and the like. In particular, a narrow gap is provided between the armature winding and the stator which supports it and this gap is filled with an externally pressurized viscous liquid. The liquid is externally pressurized sufficiently to balance the static loads on the armature winding. Transient mechanical loads which deform the armature winding alter the gap dimensions and thereby additionally pressurize the viscous liquid to oppose the armature winding deformation and more nearly uniformly to distribute the resulting mechanical stresses.

Smith, Jr., Joseph L. (Concord, MA); Kirtley, Jr., James L. (Brookline, MA)

1981-01-01

171

Generalization of Filament Braiding Model for Amyloid Fibril Assembly  

NASA Astrophysics Data System (ADS)

Research into the formation of amyloid fibrils is motivated by their association with several prominent diseases, among these Alzheimer's Disease, Parkinson's Disease and amyloidosis. Previous work in monitering the aggregation of immunoglobulin light chains to form amyloid fibrils suggests a braided structure where filaments and protofibrils wind together to form Type I and Type II fibrils. Non-contact atomic force microscopy is used to image and explore the kinetics of several other amyloid fibril forming proteins in an effort to generalize the filament braiding model. Included in this study are insulin and the B1 domain of G. Both of these have been shown to form fibrils in vitro. Alpha-synuclein is also included in this study. It is involved in the formation of Lewy bodies in Parkinson's Disease. The fourth protein used in this comparitive study is human amylin that is the cause of a systemic amyloidosis. Results from these four proteins and their associated fibrils are compared to the Ig light chain fibril structure in an effort to show the universality of the filament braiding model.

Pope, Maighdlin; Ionescu-Zanetti, Cristian; Khurana, Ritu; Carter, Sue

2001-03-01

172

A penny-shaped crack in a filament reinforced matrix. 1: The filament model  

NASA Technical Reports Server (NTRS)

The electrostatic problem of a penny-shaped crack in an elastic matrix which reinforced by filaments or fibers perpendicular to the plane of the crack was studied. The elastic filament model was developed for application to evaluation studies of the stress intensity factor along the periphery of the crack, the stresses in the filaments or fibers, and the interface shear between the matrix and the filaments or fibers. The requirements expected of the model are a sufficiently accurate representation of the filament and applicability to the interaction problems involving a cracked elastic continuum with multi-filament reinforcements. The technique for developing the model and numerical examples of it are shown.

Erdogan, F.; Pacella, A. H.

1973-01-01

173

RIS0-M-2432 SIMPLIFIED LAWS OF SIMIALRITY FOR WIND TURBINE ROTORS  

E-print Network

turbine, in order to improve the machine, optimize or adapt it to another wind climate than originally operation. The optimization of a stall-regulated wind turbine to different wind climates by variation-SPEED OPERATION OF A WIND TURBINE 16 6. OPTIMIZATION OF A STALL-REGULATED WIND TURBINE TO DIFFERENT WIND CLIMATES

174

Simple Machines  

NSDL National Science Digital Library

Through a five-lesson series with five activities, students are introduced to six simple machines—inclined plane, wedge, screw, lever, pulley, wheel-and-axle—as well as compound machines, which are combinations of two or more simple machines. Once students understand about work (work = force x distance), they become familiar with the machines' mechanical advantages, and see how they make work easier. Through an introduction to compound machines, students begin to think critically about machine inventions and their pervasive roles in our lives. After learning about Rube Goldberg contraptions—absurd inventions that complete simple tasks in complicated ways—they evaluate the importance and usefulness of the many machines around them. Through the hands-on activities, students draw designs for contraptions that could move a circus elephant into a rail car, create a construction site ramp design by measuring different inclined planes and calculating the ideal vs. actual mechanical advantage of each, compare the theoretical and actual mechanical advantages of different pulley systems conceived to save a whale, build and test grape catapults made with popsicle sticks and rubber bands, and follow the steps of the engineering design process to design and build Rube Goldberg machines.

Integrated Teaching and Learning Program,

175

Electric machine  

SciTech Connect

An interior permanent magnet electric machine is disclosed. The interior permanent magnet electric machine comprises a rotor comprising a plurality of radially placed magnets each having a proximal end and a distal end, wherein each magnet comprises a plurality of magnetic segments and at least one magnetic segment towards the distal end comprises a high resistivity magnetic material.

El-Refaie, Ayman Mohamed Fawzi (Niskayuna, NY); Reddy, Patel Bhageerath (Madison, WI)

2012-07-17

176

Simple Machines  

NSDL National Science Digital Library

How do you get a glove and a ball up to your tree house? One answer is to use a pulley. A pulley is a simple machine. In this original KET interactive, children learn about the basic workings of three simple machines.

2010-11-03

177

Nonplanar machines  

SciTech Connect

This talk examines methods available to minimize, but never entirely eliminate, degradation of machine performance caused by terrain following. Breaking of planar machine symmetry for engineering convenience and/or monetary savings must be balanced against small performance degradation, and can only be decided on a case-by-case basis. 5 refs.

Ritson, D. (Stanford Linear Accelerator Center, Menlo Park, CA (USA))

1989-05-01

178

Design and Performance of a Converter Optimized AC Machine  

Microsoft Academic Search

The design and performance of a unique concentrated winding machine specifically designed for operation with a static power converter is described. When operating in tonjunction with a converter supply, the machine is theoretically capable of 15 percent more power output for the same active copper and iron than a conventionally designed synchronous machine of the same rating. The performance of

Thomas A. Lipo; Feng X. Wang

1984-01-01

179

Filament formation and evolution in buoyant coastal waters: Observation and modelling  

NASA Astrophysics Data System (ADS)

This paper presents a detailed analysis of the formation and subsequent evolution of filament-like structures observed in a relatively small area of the mid-Tyrrhenian Sea (Mediterranean Sea). The filament dynamics and potential impact on the cross-shelf exchange budget are investigated based on a combined use of remote sensing imagery, in situ data and numerical modelling. The complexity of these phenomena is shown by focusing on four distinct events that led to cross-shelf transport, each representative of a different dynamic process and a distinct expected impact on the coastal area. A systematic analysis of available observations for the years 1998-2006 underlines the role of the interplay of atmospheric freshwater fluxes, river loads and wind stress variations, which may create favourable conditions for the convergence of shelf waters (particularly at coastal capes) and the subsequent formation of short-lived filaments along the coast. The response of the buoyant coastal waters to periods of wind reversal and fluctuating freshwater discharge rates is examined through idealised Regional Ocean Modeling System (ROMS) simulations. The filaments observed in remote sensing imagery were well reproduced by the numerical exercise, where the filaments appear as organised submesoscale structures that possess high relative vorticity and develop at the river mouths or adjacent capes. In both scenarios, the filaments appear largely determined by (i) the presence of a buoyancy anomaly, (ii) the angle between the wind pulse direction and the coast and (iii) irregularities in the coastal profile. The ensemble of results suggests that the occurrence of such transient, intense structures may contribute considerably to the biological variability and cross-shelf exchange in coastal areas with similar traits.

Iermano, Ilaria; Liguori, Giovanni; Iudicone, Daniele; Buongiorno Nardelli, Bruno; Colella, Simone; Zingone, Adriana; Saggiomo, Vincenzo; Ribera d'Alcalà, Maurizio

2012-11-01

180

Simple Machines  

NSDL National Science Digital Library

In this physical science mini-unit designed for grade 8 students, six groups of students each specialize in one of the six simple machines. As outlined here, the unit covers three to four class periods and deals with forces and motion, work and machines, and mechanical advantage. The teacher introduces students to these topics using the included PowerPoint presentation. Student groups do library or Internet research on their particular simple machine and then experiment with it in class. In culminating oral presentations, each group explains the function(s) of their machine, its mechanical advantage, and some of its everyday uses. The unit plan contains a worksheet for each simple machine group, a notes sheet, teacher pointers, and an assessment rubric.

Spaulding, Anna

2004-01-01

181

The Geography of Wind Energy: Problem Solving Activities.  

ERIC Educational Resources Information Center

Today there are many attempts to use wind machines to confront the increasing costs of electricity. Described are activities to help secondary students understand wind energy, its distribution, applications, and limitations. (RM)

Lahart, David E.; Allen, Rodney F.

1985-01-01

182

Response of a flexible filament in a flowing soap film subject to a forced vibration  

NASA Astrophysics Data System (ADS)

The interactions between flexible plates and fluids are important physical phenomena. A flag in wind is one of the most simplified and classical models for studying the problem. In this paper, we investigated the response of a flag in flow with an externally forced vibration by using flexible filaments and soap film. Experiments show that for a filament that is either in oscillation or stationary, the external forced vibration leads to its oscillation. A synchronization phenomenon occurs in the experiments. A small perturbation leads to a large response of flapping amplitude in response. The insight provided here is helpful to the applications in the flow control, energy harvesting, and bionic propulsion areas.

Jia, Laibing; Xiao, Qing; Wu, Haijun; Wu, Yanfeng; Yin, Xiezhen

2015-01-01

183

Development of the WTS-4 wind turbine design  

NASA Astrophysics Data System (ADS)

Design features, developmental aspects, and financial projections for the WTS-4 4 MW wind turbine are presented. The WTS-4 is a horizontal axis, downwind, two-bladed, variable pitch machine. Start-up is at 7 m/s, rated power is reached at 15 m/s, and shut-down is set at 27 m/s, with all controls operating in a stand-alone mode by means of microprocessors. Each blade is 125 ft long, constructed of filament wound fiberglass reinforced epoxy, and attached at the root to a teetered steel alloy hub, which compensates for the shear caused by the tower shadow. Pitch is controlled by an electrohydraulic mechanism, and can be effected at a rate of 5 deg/s. Details of the nacelle components and costruction are provided, together with features of the system controller and design trade-offs. Cost comparisons with utility scale coal and oil baseload generation plants indicate that wind turbines will become cost competitive by 1985 and are favored thereafter.

Hasbrouck, T. M.; Divalentin, E.

184

The nonlinear evolution of magnetized solar filaments  

NASA Technical Reports Server (NTRS)

Thermal instability driven by optically thin radiation is believed to initiate the formation of plasma filaments in the solar corona. The fact that filaments are observed generally to separate regions of opposite, line-of-sight, magnetic polarity in the underlying photosphere suggests that filament formation requires the presence of a highly sheared, local magnetic field. Two-dimensional, nonlinear, magnetohydrodynamic simulations of the local genesis and growth of solar filaments in a force-free, sheared, magnetic field were performed, and the evolution of generic perturbations possessing broad spatial profiles was traced. It was found that simulations of the evolution of initial random-noise perturbations produce filamentary plasma structures that exhibit densities and temperatures characteristic of observed solar filaments. Furthermore, in each of these simulations, the filament axis lies at a finite angle with respect to the local magnetic field, consistent with solar observations.

Sparks, L.; Van Hoven, G.; Schnack, D. D.

1990-01-01

185

Evolution of Barb Angle and Filament Eruption  

NASA Astrophysics Data System (ADS)

H? observations of a quiescent U-shaped filament were obtained at Big Bear Solar Observatory and at Hida Observatory with the Flare Monitoring Telescope. The filament was located in the southern hemisphere on 1998 November 4. We study the evolution of the angle of a barb with respect to the axis of the filament and find the evolution can be divided into two phases: a rise from the acute phase to the obtuse phase and a fall. Thus, this indicates that the chirality of this barb changes with time. Moreover, in the process of evolution, we find that interconnection of the part of the filament bearing the barb with the whole filament became either weakened or strengthened. We impute the final eruption of the filament to the chirality evolution of the barb.

Su, J. T.; Liu, Y.; Zhang, H. Q.; Kurokawa, H.; Yurchyshyn, V.; Shibata, K.; Bao, X. M.; Wang, G. P.; Li, C.

2005-09-01

186

Motion, decay and merging of vortex filaments  

NASA Technical Reports Server (NTRS)

The asymptotic solutions of Navier-Stokes equations for vortex filaments of finite strength with small effective vortical cores are summarized. Emphases are placed on the physical meaning and the practical limit to the applicability of the asymptotic solution. Finite-difference solutions of Navier-Stokes equations for the merging of the filament(s) are described. It is focused on the development of the approximate boundary conditions for the computational domain.

Liu, C. H.; Ting, L.

1988-01-01

187

Plasticity of Intermediate Filament Subunits  

PubMed Central

Intermediate filaments (IFs) assembled in vitro from recombinantly expressed proteins have a diameter of 8–12 nm and can reach several micrometers in length. IFs assemble from a soluble pool of subunits, tetramers in the case of vimentin. Upon salt addition, the subunits form first unit length filaments (ULFs) within seconds and then assembly proceeds further by end-to-end fusion of ULFs and short filaments. So far, IF subunits have mainly been observed by electron microscopy of glycerol sprayed and rotary metal shadowed specimens. Due to the shear forces during spraying the IF subunits appear generally as straight thin rods. In this study, we used atomic force microscopy (AFM), cryo-electron microscopy (cryo-EM) combined with molecular modeling to investigate the conformation of the subunits of vimentin, desmin and keratin K5/K14 IFs in various conditions. Due to their anisotropic shape the subunits are difficult to image at high resolution by cryo-EM. In order to enhance contrast we used a cryo-negative staining approach. The subunits were clearly identified as thin, slightly curved rods. However the staining agent also forced the subunits to aggregate into two-dimensional networks of dot-like structures. To test this conformational change further, we imaged dried unfixed subunits on mica by AFM revealing a mixture of extended and dot-like conformations. The use of divalent ions such as calcium and magnesium, as well as glutaraldehyde exposure favored compact conformations over elongated ones. These experimental results as well as coarse-grained molecular dynamics simulations of a vimentin tetramer highlight the plasticity of IF subunits. PMID:20814582

Hoenger, Andrea; Buehler, Markus J.; Kreplak, Laurent

2010-01-01

188

Midterm periods of solar filaments  

NASA Astrophysics Data System (ADS)

On the basis of the Carte Synoptique catalogue of solar filaments from March 1919 to December 1989, we measure power spectra of detrended full-disk (FSFNs, latitudinal bands: 0?-90?), low-latitude (LSFNs, latitudinal bands: <50?), and high-latitude (HSFNs, latitudinal bands: ?50?) solar filament numbers by Maximum Entropy Method (MEM) and Continuous wavelet transform to detect midterm periods. It is found as the following: (1) FSFNs and LSFNs have the same midterm periodicity, while HSFNs show a different midrange periodicity. Some periods frequently mentioned in other solar indices are also detected from the solar filament numbers, such as 2-3 year period (quasi-biennial oscillation—QBO), ˜1.7 year, ˜1.3 year, ˜1 year, 150-157 day period (Rieger period), and 6.0-6.4 months (Rieger-type period). These periods are intermittent during considered time span. Some of them are missing in some solar cycles. (2) QBO is detected from total data and most solar cycles of FSFNs, LSFNs, and HSFNs. It may be related to oscillation of magnetic field of solar surface. (3) Approximately 1.3 year period occasionally appears, but ˜1.7 year period is hardly seen. These two periods probably are seasonal effects. (4) Approximately 1 year period is detected from both total data and every solar cycle of FSFNs and LSFNs but hardly detected from HSFNs. It is perhaps connected with sunspot activity. (5) Rieger period of 5.0-5.2 months is detected in total data and even solar cycles of HSFNs. Rieger-type period of 6.0-6.4 months is found in total data and most solar cycles, except cycle 18 of LSFNs and FSFNs. These periods seem to be subharmonics of ˜11 year period.

Zou, Peng; Li, Qixiu

2014-12-01

189

A review of the SERI wind energy innovative systems program  

Microsoft Academic Search

Features of innovative wind energy conversion systems evaluated and\\/or tested at the Solar Energy Research Institute are reviewed. Cost, performance, and engineering data were acquired for the machines, along with proof-of-concept demonstrations. Machines which were examined included a straight-bladed vertical axis wind turbine with circulation controlled airfoils, the Grumman tornado wind energy tower with louvers, a wind-powered charged aerosol generator

I. E. Vas; P. South

1980-01-01

190

Deep coronal hole associated with quiescent filament  

NASA Astrophysics Data System (ADS)

We present a study of the morphology of quiescent filament observed by H-alpha Solar Telescope at Bosscha Observatory in association with coronal hole observed by Atmospheric Imaging Assembly (AIA) instrument in 193 Å from Solar Dynamics Observatory. H-alpha images were processed by imaging softwares, namely Iris 5.59 and ImageJ, to enhance the signal to noise ratio and to identify the filament features associated with coronal hole. For images observed on October 12, 2011, November 14, 2011 and January 2, 2012, we identified distinct features of coronal holes above the quiescent filaments. This associated coronal holes have filament-like morphology with a thick long thread as it's `spine', defined as Deep Coronal Hole. Because of strong magnetic field of sunspot, these filaments and coronal holes emerged far from active region and lasted for several days. It is interesting as for segmented filament, deep coronal holes above the filaments lasted for a quite long period of time and merged. This association between filament and deep coronal hole can be explained by filament magnetic loop.

Kesumaningrum, Rasdewita; Herdiwidjaya, Dhani

2014-03-01

191

On the equilibrium of rotating filaments  

NASA Astrophysics Data System (ADS)

The physical properties of the so-called Ostriker isothermal, non-rotating filament have been classically used as benchmark to interpret the stability of the filaments observed in nearby clouds. However, such static picture seems to contrast with the more dynamical state observed in different filaments. In order to explore the physical conditions of filaments under realistic conditions, in this work we theoretically investigate how the equilibrium structure of a filament changes in a rotating configuration. To do so, we solve the hydrostatic equilibrium equation assuming both uniform and differential rotations independently. We obtain a new set of equilibrium solutions for rotating and pressure truncated filaments. These new equilibrium solutions are found to present both radial and projected column density profiles shallower than their Ostriker-like counterparts. Moreover, and for rotational periods similar to those found in the observations, the centrifugal forces present in these filaments are also able to sustain large amounts of mass (larger than the mass attained by the Ostriker filament) without being necessary unstable. Our results indicate that further analysis on the physical state of star-forming filaments should take into account rotational effects as stabilizing agents against gravity.

Recchi, S.; Hacar, A.; Palestini, A.

2014-10-01

192

Observations of an active region filament  

NASA Astrophysics Data System (ADS)

An active region filament was well observed on September 4, 2002 with THEMIS at the Teide observatory and SOHO/MDI. The full Stokes parameters of the filament were obtained in H? and FeI 6302 Å lines. Using the data, we have studied the fine structure of the filament and obtained the parameters at the barb endpoints, including intensity, velocity and longitudinal magnetic field. Our results indicate: (a) the Doppler velocities are quiet different at barb endpoints; (b) the longitudinal magnetic fields at the barb endpoints are very weak; (c) there is a strong magnetic field structure under the filament spine.

Zong, W. G.; Tang, Y. H.; Fang, C.; Xu, A. A.

193

Scribbling Machines  

NSDL National Science Digital Library

In this activity, learners explore electronics and motion by making a Scribbling Machine, a motorized contraption that moves in unusual ways and leaves a mark to trace its path. Itâs made from simple materials and is based on the idea of motion created by an offset motor. Try using harvested motors and switches from discarded toys and electronics to make your Scribbling Machine - this not only keeps costs down, but is a playful and inventive way to explore how everyday objects work. To take the activity further, you can also incorporate PicoCrickets to make your Scribbling Machine more intelligent and to explore computers.

Exploratorium

2013-01-30

194

IMPLEMENTATION OF WIND TURBINE CONTROLLERS W.E.Leithead  

E-print Network

. The standard commercial design of wind turbine is a horizontal-axis grid-connected up-wind machine of wind turbines, which are presently being developed, will include large-scale designs with a ratingIMPLEMENTATION OF WIND TURBINE CONTROLLERS D.J.Leith W.E.Leithead Department of Electronic

Duffy, Ken

195

Force-Induced Dynamical Properties of Multiple Cytoskeletal Filaments Are Distinct from that of Single Filaments  

PubMed Central

How cytoskeletal filaments collectively undergo growth and shrinkage is an intriguing question. Collective properties of multiple bio-filaments (actin or microtubules) undergoing hydrolysis have not been studied extensively earlier within simple theoretical frameworks. In this paper, we study the collective dynamical properties of multiple filaments under force, and demonstrate the distinct properties of a multi-filament system in comparison to a single filament. Comparing stochastic simulation results with recent experimental data, we show that multi-filament collective catastrophes are slower than catastrophes of single filaments. Our study also shows further distinctions as follows: (i) force-dependence of the cap-size distribution of multiple filaments are quantitatively different from that of single filaments, (ii) the diffusion constant associated with the system length fluctuations is distinct for multiple filaments, and (iii) switching dynamics of multiple filaments between capped and uncapped states and the fluctuations therein are also distinct. We build a unified picture by establishing interconnections among all these collective phenomena. Additionally, we show that the collapse times during catastrophes can be sharp indicators of collective stall forces exceeding the additive contributions of single filaments. PMID:25531397

Das, Dipjyoti; Das, Dibyendu; Padinhateeri, Ranjith

2014-01-01

196

Harnessing Wind  

NSDL National Science Digital Library

Students are introduced to the ways that engineers study and harness the wind. They learn about the different kinds of winds and how to measure wind direction. In addition, they learn how air pressure creates winds and how engineers design and test wind turbines to harness renewable wind energy.

Integrated Teaching And Learning Program

197

Math Machines  

NSDL National Science Digital Library

The mission of the Math Machines organization is to "improve the quality of mathematical education, enhance the transfer of mathematical thinking into other classes, and increase students' ability to apply rigorous mathematics outside the classroom." Their website supports a National Science Foundation ATE grant-supported project designed to improve teaching in the areas of Mathematics, Science, and Technology at the high school and college levels. This improved learning results from using math, science, and technology principles to build and control various machines such as pointers and robots or "math machines", which are simple devices that provide an immediate, physical, dynamic expression to abstract mathematical equations. The website provides information links on Educational Theory, Classroom Activities, Project Workshops, Calculators & Programs, and Machine Construction Instructions for Building: Closed Circuits, Servo Motors, Controllers, Robot Boards and more. There is also contact information, an FAQ section, as well as upcoming events.

2010-05-18

198

Microcyle Conidiation in Filamentous Fungi  

PubMed Central

The typical life cycle of filamentous fungi commonly involves asexual sporulation after vegetative growth in response to environmental factors. The production of asexual spores is critical in the life cycle of most filamentous fungi. Normally, conidia are produced from vegetative hyphae (termed mycelia). However, fungal species subjected to stress conditions exhibit an extremely simplified asexual life cycle, in which the conidia that germinate directly generate further conidia, without forming mycelia. This phenomenon has been termed as microcycle conidiation, and to date has been reported in more than 100 fungal species. In this review, first, we present the morphological properties of fungi during microcycle conidiation, and divide microcycle conidiation into four simple categories, even though fungal species exhibit a wide variety of morphological differences during microcycle conidiogenesis. Second, we describe the factors that influence microcycle conidiation in various fungal species, and present recent genetic studies that have identified the genes responsible for this process. Finally, we discuss the biological meaning and application of microcycle conidiation. PMID:24808726

Jung, Boknam; Kim, Soyeon

2014-01-01

199

Wind Turbine Acoustics  

NASA Technical Reports Server (NTRS)

Wind turbine generators, ranging in size from a few kilowatts to several megawatts, are producing electricity both singly and in wind power stations that encompass hundreds of machines. Many installations are in uninhabited areas far from established residences, and therefore there are no apparent environmental impacts in terms of noise. There is, however, the potential for situations in which the radiated noise can be heard by residents of adjacent neighborhoods, particularly those neighborhoods with low ambient noise levels. A widely publicized incident of this nature occurred with the operation of the experimental Mod-1 2-MW wind turbine, which is described in detail elsewhere. Pioneering studies which were conducted at the Mod-1 site on the causes and remedies of noise from wind turbines form the foundation of much of the technology described in this chapter.

Hubbard, Harvey H.; Shepherd, Kevin P.

2009-01-01

200

Machine Vision  

NSDL National Science Digital Library

An overview of a generic image-based machine vision system is provided on this Web site (1). The tutorial describes the main components of such a system, how its accuracy is measured, and what scientific and industrial applications benefit from machine vision. A more technical perspective of machine vision technology is given in an online publication of the Automated Imaging Association (2). Monthly feature articles discuss breaking issues related to machine vision, and several technical papers can be downloaded, which are sorted into categories such as three dimensional imaging and nanotechnology. Researchers from the MIT's Artificial Intelligence Laboratory (3) are investigating how to enable a computer to interpret visual and audio signals from its human user. By using machine perception systems to track the user's gaze, for example, the computer could ascertain the focus of the user's attention, thereby facilitating interaction between the human and the computer. The project's homepage includes numerous research papers, as well as video demonstrations of some of its systems. Machine vision is also finding its way into vehicles. A March 2003 news article (4) highlights a field test in Michigan of a collision avoidance system that uses, among other things, machine vision to warn drivers that they are approaching a slower or stopped object too quickly. The 3D Computer Vision Group at Carnegie Mellon University (5) is involved in several projects, including three dimensional object recognition and humanoid robot vision. Many of the group's recent publications are available for download. NASA's Mars Exploration Rovers, the second of which was launched in July 2003, have vision systems that will let them safely navigate rough terrain. These systems are described in this conference paper (6), including specifics of the stereo vision algorithm and insights into future missions. A new implementation of machine vision comes from a former researcher from Cambridge University. His shape recognition system, which is detailed in this news article (7), is reportedly much more related to human visual processes than existing techniques. For additional developments related to this evolving technology, Machine Vision News (8) has information about worldwide research and new applications of machine vision systems.

Leske, Cavin.

201

Lamp automatically switches to new filament on burnout  

NASA Technical Reports Server (NTRS)

Lamp with primary and secondary filaments has a means for automatic switching to the secondary filament at primary filament burnout. Lamp failures and resultant expenses during oscillograph printing are appreciably reduced.

Ingle, W. B.

1966-01-01

202

Actin filament mechanics in the laser trap  

Microsoft Academic Search

Summary Numerous biological processes, including muscular contraction, depend upon the mechanical properties of actin filaments. One such property is resistance to bending (flexural rigidity, EI). To estimate EI, we attached the ends of fluorescently labelled actin filaments to two microsphere 'handles' captured in independent laser traps. The positions of the traps were manipulated to apply a range of tensions (0-8

D. E. D UPUIS; D. M. W ARSHAW

1997-01-01

203

A First Approach to Filament Dynamics  

ERIC Educational Resources Information Center

Modelling elastic filament dynamics is a topic of high interest due to the wide range of applications. However, it has reached a high level of complexity in the literature, making it unaccessible to a beginner. In this paper we explain the main steps involved in the computational modelling of the dynamics of an elastic filament. We first derive…

Silva, P. E. S.; de Abreu, F. Vistulo; Simoes, R.; Dias, R. G.

2010-01-01

204

Organic Acid Production by Filamentous Fungi  

E-print Network

12 Organic Acid Production by Filamentous Fungi Jon K. Magnuson and Linda L. Lasure 1. Introduction of this extraordinary capacity of filamentous fungi to produce organic acids in high concentrations will allow greater fungi, and this review is limited to that group. Although yeasts including Saccharomyces cerevisiae

205

Analysis of electromechanical interactions in a flywheel system with a doubly fed induction machine  

E-print Network

This paper analyzes the electromechanical inter-action in a flywheel system with a doubly fed induction machine, used for wind farm power smoothing or grid frequency response control. The grid-connected electrical machine ...

Ran, Li

206

Underwater Laser Filamentation and Electrical Discharge Guiding  

NASA Astrophysics Data System (ADS)

Techniques to trigger and guide underwater electrical discharges using a laser are currently being developed at NRL. This work may be useful for a variety of applications, including advanced micromachining. As part of this development we are studying underwater optical filaments. Optical filamentation is the extended propagation of a small diameter high-power laser beam, thought to result from a balance between Kerr self-focusing and ionization-induced defocusing, and typically includes a coincident plasma column. Laser heating and hydrodynamic expansion can also result in subsequent vapor channel formation. Both the plasma column and vapor channel can be useful structures for guiding electrical discharges. Our group has for the first time demonstrated and characterized ns underwater filaments. Using a 60 mJ, 5 ns, 532 nm laser, we measured filament diameters of ˜100 ?m and propagation > 30 Rayleigh lengths. Underwater optical filament measurements, as well as results from ongoing laser-guided underwater discharge experiments, will be presented.

Jones, T. G.; Helle, M. H.; Kaganovich, D.; Gordon, D.; Ting, A.

2011-11-01

207

Enigmatic reticulated filaments in subsurface granite.  

PubMed

In the last few years, geomicrobiologists have focused their researches on the nature and origin of enigmatic reticulated filaments reported in modern and fossil samples from limestone caves and basalt lava tubes. Researchers have posed questions on these filaments concerning their nature, origin, chemistry, morphology, mode of formation and growth. A tentative microbial origin has been elusive since these filaments are found as hollow tubular sheaths and could not be affiliated to any known microorganism. We describe the presence of similar structures in a 16th century granite tunnel in Porto, Northwest Portugal. The reticulated filaments we identify exhibit fine geometry surface ornamentation formed by cross-linked Mn-rich nanofibres, surrounded by a large amount of extracellular polymeric substances. Within these Mn-rich filaments we report for the first time the occurrence of microbial cells. PMID:23760930

Miller, A Z; Hernández-Mariné, M; Jurado, V; Dionísio, A; Barquinha, P; Fortunato, E; Afonso, M J; Chaminé, H I; Saiz-Jimenez, C

2012-12-01

208

Extensible Wind Towers  

NASA Astrophysics Data System (ADS)

The diffusion of wind energy generators is restricted by their strong landscape impact. The PERIMA project is about the development of an extensible wind tower able to support a wind machine for several hundred kW at its optimal working height, up to more than 50 m. The wind tower has a telescopic structure, made by several tubes located inside each other with their axis in vertical direction. The lifting force is given by a jack-up system confined inside a shaft, drilled below the ground level. In the retracted tower configuration, at rest, tower tubes are hidden in the foundation of the telescopic structure, located below the ground surface, and the wind machine is the only emerging part of the system. The lifting system is based on a couple of oleodynamic cylinders that jack-up a central tube connected to the top of the tower by a spring, with a diameter smaller than the minimum tower diameter and with a length a bit greater than the length of the extended telescopic structure. The central tube works as plunger and lifts all telescopic elements. The constraint between the telescopic elements is ensured by special parts, which are kept in traction by the force of the spring and provide the resisting moment. The most evident benefit of the proposed system is attained with the use of a two-blade propeller, which can be kept horizontal in the retracted tower configuration.

Sinagra, Marco; Tucciarelli, Tullio

209

Unwinding Motion of a Twisted Active Region Filament  

NASA Astrophysics Data System (ADS)

To better understand the structures of active region filaments and the eruption process, we study an active region filament eruption in active region NOAA 11082 in detail on 2010 June 22. Before the filament eruption, the opposite unidirectional material flows appeared in succession along the spine of the filament. The rising of the filament triggered two B-class flares at the upper part of the filament. As the bright material was injected into the filament from the sites of the flares, the filament exhibited a rapid uplift accompanying the counterclockwise rotation of the filament body. From the expansion of the filament, we can see that the filament consisted of twisted magnetic field lines. The total twist of the filament is at least 5? obtained by using a time slice method. According to the morphology change during the filament eruption, it is found that the active region filament was a twisted flux rope and its unwinding motion was like a solar tornado. We also find that there was a continuous magnetic helicity injection before and during the filament eruption. It is confirmed that magnetic helicity can be transferred from the photosphere to the filament. Using the extrapolated potential fields, the average decay index of the background magnetic fields over the filament is 0.91. Consequently, these findings imply that the mechanism of solar filament eruption could be due to the kink instability and magnetic helicity accumulation.

Yan, X. L.; Xue, Z. K.; Liu, J. H.; Kong, D. F.; Xu, C. L.

2014-12-01

210

INTERMEDIATE FILAMENTS IN SMOOTH MUSCLE  

PubMed Central

The intermediate filament (IF) network is one of the three cytoskeletal systems in smooth muscle. The type III IF proteins vimentin and desmin are major constituents of the network in smooth muscle cells and tissues. Lack of vimentin or desmin impairs contractile ability of various smooth muscle preparations, implying their important role for smooth muscle force development. The IF framework has long been viewed as a fixed cytostructure that solely provides mechanical integrity for the cell. However, recent studies suggest that the IF cytoskeleton is dynamic in mammalian cells in response to various external stimulation. In this review, the structure and biological properties of IF proteins in smooth muscle are summarized. The role of IF proteins in the modulation of smooth muscle force development and redistribution/translocation of signaling partners (such as p130 Crk-associated substrate, CAS) is depicted. This review also summarizes our latest understanding on how the IF network may be regulated in smooth muscle. PMID:18256275

Tang, Dale D.

2008-01-01

211

Possibilities and limitations of wind energy utilisation  

NASA Astrophysics Data System (ADS)

The existing wind resource, the most favorable locations, applications, and designs of windpowered generators are reviewed, along with descriptions of current and historic wind turbines and lines of research. Coastal regions, plains, hill summits, and mountains with funneling regions are noted to have the highest annual wind averages, with energy densities exceeding the annual solar insolation at average wind speeds of 5-7.9 m/sec. Applications for utility-grade power production, for irrigation, for mechanical heat production, and for pumped storage in water towers or reservoirs are mentioned, as well as electrical power production in remote areas and for hydrogen production by electrolysis. Power coefficients are discussed, with attention given to the German Growian 3 MW machine. It is shown that the least economically sound wind turbines, the machines with outputs below 100 kW, can vie with diesel plant economics in a good wind regime if the wind turbine operates for 15 yr.

Feustel, J.

1981-10-01

212

On the Fatigue Analysis of Wind Turbines  

SciTech Connect

Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. Operational experiences with these large rotating machines indicated that their components (primarily blades and blade joints) were failing at unexpectedly high rates, which led the wind turbine community to develop fatigue analysis capabilities for wind turbines. Our ability to analyze the fatigue behavior of wind turbine components has matured to the point that the prediction of service lifetime is becoming an essential part of the design process. In this review paper, I summarize the technology and describe the ''best practices'' for the fatigue analysis of a wind turbine component. The paper focuses on U.S. technology, but cites European references that provide important insights into the fatigue analysis of wind turbines.

Sutherland, Herbert J.

1999-06-01

213

Drum cutter mining machine  

Microsoft Academic Search

A drum cutter mining machine includes a machine frame with a winch having a drive wheel to engage a rack or chain which extends along the path of travel by the mining machine to propel the machine along a mine face. The mining machine is made up of discrete units which include a machine body and machine housings joined to

K. Oberste-beulmann; H. Schupphaus

1980-01-01

214

Automatic Detect and Trace of Solar Filaments  

NASA Astrophysics Data System (ADS)

We developed a series of methods to automatically detect and trace solar filaments in solar H? images. The programs are able to not only recognize filaments and determine their properties, such as the position, the area and other relevant parameters, but also to trace the daily evolution of the filaments. For solar full disk H? images, the method consists of three parts: first, preprocessing is applied to correct the original images; second, the Canny edge-detection method is used to detect the filaments; third, filament properties are recognized through the morphological operators. For each H? filament and its barb features, we introduced the unweighted undirected graph concept and adopted Dijkstra shortest-path algorithm to recognize the filament spine; then, using polarity inversion line shift method for measuring the polarities in both sides of the filament to determine the filament axis chirality; finally, employing connected components labeling method to identify the barbs and calculating the angle between each barb and spine to indicate the barb chirality. Our algorithms are applied to the observations from varied observatories, including the Optical & Near Infrared Solar Eruption Tracer (ONSET) in Nanjing University, Mauna Loa Solar Observatory (MLSO) and Big Bear Solar Observatory (BBSO). The programs are demonstrated to be effective and efficient. We used our method to automatically process and analyze 3470 images obtained by MLSO from January 1998 to December 2009, and a butterfly diagram of filaments is obtained. It shows that the latitudinal migration of solar filaments has three trends in the Solar Cycle 23: The drift velocity was fast from 1998 to the solar maximum; after the solar maximum, it became relatively slow and after 2006, the migration became divergent, signifying the solar minimum. About 60% filaments with the latitudes larger than 50 degree migrate towards the Polar Regions with relatively high velocities, and the latitudinal migrating speeds in the northern and the southern hemispheres do not differ significantly in the Solar Cycle 23. We also processed a number of relatively high-resolution H? images obtained by BBSO. It is found that in some cases, the filament axis has single chirality and the associated magnetic field also has single helicity, while its barbs in different parts of it have opposite barb chirality.

Fang, Cheng; Chen, P. F.; Tang, Yu-hua; Hao, Qi; Guo, Yang

215

Simulating Turing Machines on Maurer Machines  

E-print Network

Simulating Turing Machines on Maurer Machines J.A. Bergstra1,2 and C.A. Middelburg3 1 Programming MB Eindhoven, the Netherlands keesm@win.tue.nl Abstract. Maurer machines are much closer to real computers than Turing machines. Computer instructions play a prominent part in Mau- rer machines. We show

van der Zwaag, Mark

216

Culture Machine  

NSDL National Science Digital Library

Culture Machine is a new, refereed, electronic journal encompassing cultural studies and cultural theory. The international editorial board of the interactive journal aims to "generat[e] research in culture and theory" by promoting and publishing "the most provocative of new work." The theme of the inaugural issue is Taking Risks with the Future. Content includes articles such as Life After Death of the Text by Johan Fornas, Cultural Studies in the Clouds: Mourning for Detail by Tadeusz Slawek, and The Future States of Politics by Kenneth Surin. Culture Machine is hosted by the University of Teesside, England.

217

WIND ENERGY RESEARCH AT UNIVERSITY AND FEDERAL LEVELS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Modern wind energy research began not long after the 1973 oil embargo. The Federal government established programs for large machines, small machines, wind resources, and applications in rural and remote areas. The research for the applications in rural and remote areas was conducted by the USDA-Ag...

218

DOE/NASA Lewis large wind turbine program  

NASA Technical Reports Server (NTRS)

An overview of the large wind turbine activities managed by NASA is given. These activities include resuls from the first and second generation field machines (Mod-0A, -1, and -2), the status of the Department of Interior WTS-4 machine for which NASA is responsible for technical management, and the design phase of the third generation wind turbines (Mod-5).

Thomas, R. L.

1982-01-01

219

Force-induced dynamical properties of multiple cytoskeletal filaments are distinct from that of single filaments  

E-print Network

How cytoskeletal filaments collectively undergo growth and shrinkage is an intriguing question. Collective properties of multiple bio-filaments (actin or microtubules) undergoing hydrolysis, have not been studied extensively earlier, within simple theoretical frameworks. In this paper, we show that collective properties of multiple filaments under force are very distinct from the properties of a single filament under similar conditions -- these distinctions manifest as follows: (i) the collapse time during collective catastrophe for a multifilament system is much larger than that of a single filament with the same average length, (ii) force-dependence of the cap-size distribution of multiple filaments are quantitatively different from that of single filament, (iii) the diffusion constant associated with the system length fluctuations is distinct for multiple filaments, (iv) switching dynamics of multiple filaments between capped and uncapped states and the fluctuations therein are also distinct. We build a unified picture by establishing interconnections among all these collective phenomena. Additionally, we show that the collapse times during catastrophes can be sharp indicators of collective stall forces exceeding the additive contributions of single filaments.

Dipjyoti Das; Dibyendu Das; Ranjith Padinhateeri

2014-03-30

220

Polymeric filament thinning and breakup in microchannels  

E-print Network

The effects of elasticity on filament thinning and breakup are investigated in microchannel cross flow. When a viscous solution is stretched by an external immiscible fluid, a low 100 ppm polymer concentration strongly affects the breakup process, compared to the Newtonian case. Qualitatively, polymeric filaments show much slower evolution, and their morphology features multiple connected drops. Measurements of filament thickness show two main temporal regimes: flow- and capillary-driven. At early times both polymeric and Newtonian fluids are flow-driven, and filament thinning is exponential. At later times, Newtonian filament thinning crosses over to a capillary-driven regime, in which the decay is algebraic. By contrast, the polymeric fluid first crosses over to a second type of flow-driven behavior, in which viscoelastic stresses inside the filament become important and the decay is again exponential. Finally, the polymeric filament becomes capillary-driven at late times with algebraic decay. We show that the exponential flow thinning behavior allows a novel measurement of the extensional viscosities of both Newtonian and polymeric fluids.

P. E. Arratia; J. P. Gollub; D. J. Durian

2007-03-15

221

Contraction of Asymmetric Newtonian Liquid Filaments  

NASA Astrophysics Data System (ADS)

Understanding the dynamics of satellite drops is important in several industrial applications involving drop formation including inkjet printing, electrospraying and atomization. The precursor to these satellite drops is a slender liquid filament that connects an about-to-form drop to the rest of the liquid in the nozzle. Once a filament is formed, it either contracts into a single satellite or breaks into multiple satellites, due to surface tension. Our understanding of the contraction of Newtonian filaments in a passive ambient fluid has improved greatly over the past two decades thanks to the numerical analyses of Schulkes (1996) and Notz and Basaran (2004) who modeled the filaments as cylinders that are terminated by two identical spherical caps. However, in many situations, the filament shapes at the onset of formation may not be symmetric as in the aforementioned studies. To improve our understanding of the fluid mechanics of contraction of such asymmetric filaments, we study here the recoil of filaments whose initial shapes are sections of tapered axisymmetric cones that are terminated by two unequal spherical caps. The dynamics are studied by both a 2-D analysis and a 1-D slender-jet analysis, and the results are summarized by constructing phase diagrams involving the dimensionless groups governing the dynamics.

McGough, Patrick; Sambath, Krishnaraj; Appathurai, Santosh; Bhat, Pradeep; Harris, Michael; Basaran, Osman

2009-11-01

222

Optical Filaments and Gas Dynamics in Air  

NASA Astrophysics Data System (ADS)

Until now, the propagation dynamics of intense ultrashort laser pulses leading to optical filamentation in air has only been investigated in the frame of a dynamic balance between linear diffraction, Kerr self-focusing and plasma defocusing. This has led to the development of different theories surrounding the generation and persistence of optical filaments propagating over many Rayleigh lengths in air. These theories include wave-guiding model, moving focus model, dynamic spatial replenishment model and conical wave model. However, these models fail to capture the gas dynamics that arise from optical filaments interacting with air. In this work, we demonstrate that initial conditions are critical to the formation of optical filaments through the use of an aerodynamic window. Filament characteristics in air, such as spectral broadening, electrical conductivity and fluorescence, are measured and presented. Using these as diagnostic tools, we also show that the optical filamentation of ultrashort laser pulses can be enhanced at high repetition rates because of the thermal response of air, resulting from the interaction of each laser pulse with the modified atmospheric density distribution left behind by the preceding pulse. This is explained by the sudden deposition of energy by a filament in the air which generates a cylindrical shock wave, leaving behind a column of rarefied air. This low-density region persists for an extended period and can materially affect the propagation dynamics of an ensuing pulse that follows before the low-density region has relaxed sufficiently to ambient conditions. By further increasing the repetition rate, the onset of ionization is shifted downstream and the spectral continuum displays a stronger broadening on both sides of the original pulse spectrum. This gas dynamic interaction regime of filamentation can be utilized to enhance the length and spectral width of filaments for remote sensing and long range laser-induced high voltage discharges.

Yeak, Jeremy

223

Function Machine  

NSDL National Science Digital Library

This Java applet allows learners to explore simple linear functions. Students determine the algebraic form of a linear equation by entering inputs into the machine and by looking for patterns in the outputs. The function rules available are: integers from -10 to 10 are either added to, subtracted from, or multiplied by the input x to yield the output y.

2011-01-01

224

Decoding Machine  

NSDL National Science Digital Library

In this math lesson, learners explore variables and their uses. Learners pretend to be FBI agents and make a TOP SECRET tool that enables them to decode and find the values of hidden messages and words. Learners make their simple "decoding machines" out of paper and tape.

Lessonplans, Utah

2012-10-22

225

Leonardo's Machines  

NSDL National Science Digital Library

This Science NetLinks lesson will highlight some of Leonardo da Vinci's futuristic inventions, introducing the elements of machines. Through the use of student interactives, this lesson provides an interesting context in which students can begin to develop their ideas about the uniqueness of humans in the natural world.

Science Netlinks;

2003-03-05

226

Hot filament cvd of boron nitride films  

SciTech Connect

This patent describes a method for coating a substrate with a boron nitride film. It comprises: providing a substrate and a hot filament in a gas chamber; and introducing a borazine gas into the gas chamber so as to heat the borazine gas with the hot filament and deposit the boron nitride film on the substrate, wherein the hot filament is heated to a temperature of from about 1000[degrees] to 1800[degrees] C and the substrate is maintained at a temperature of from 100[degrees]C to 400[degrees]C.

Rye, R.R.

1992-01-07

227

WIND ENERGY Wind Energ. (2014)  

E-print Network

the turbulent atmosphere and the wind turbine wake in order to optimize the design of the wind turbine as well.com). DOI: 10.1002/we.1792 RESEARCH ARTICLE Self-similarity and turbulence characteristics of wind turbine by a single wind turbine are studied in this paper with a new large eddy simulation (LES) code, the wind

228

Large, low cost composite wind turbine blades  

NASA Technical Reports Server (NTRS)

A woven roving E-glass tape, having all of its structural fibers oriented across the tape width was used in the manufacture of the spar for a wind turbine blade. Tests of a 150 ft composite blade show that the transverse filament tape is capable of meeting structural design requirements for wind turbine blades. Composite blades can be designed for interchangeability with steel blades in the MOD-1 wind generator system. The design, analysis, fabrication, and testing of the 150 ft blade are discussed.

Gewehr, H. W.

1979-01-01

229

Apparatus for cooling an electric machine  

DOEpatents

Provided is an apparatus, for example, for use with a rotating electric machine, that includes a housing. The housing can include a housing main portion and a housing end portion. The housing main portion can be configured to be disposed proximal to a body portion of a stator section of an electric machine. The housing main portion can define a main fluid channel that is configured to conduct fluid therethrough. The housing end portion can receive fluid from said main fluid channel and direct fluid into contact with a winding end portion of a conductive winding of the stator section.

Palafox, Pepe; Gerstler, William Dwight; Shen, Xiaochun; El-Refaie, Ayman Mohamed Fawzi; Lokhandwalla, Murtuza; Salasoo, Lembit

2013-07-16

230

How Salmonella Typhimurium measure the length of their Flagellar Filaments  

E-print Network

, it is divided into three parts: the basal body, the hook, and the filament. The filament and hook are external-filament junction Basal Body MS Ring Distal Rod Proximal Rod Figure 1: Schematic diagram of flagellar motor to the cell, while the basal body is anchored in the inner and outer membranes. The filament is the largest

Keener, James P.

231

Snake Filament Eruption - Duration: 0:05.  

NASA Video Gallery

A very long solar filament that had been snaking around the Sun erupted on Dec. 6, 2010 with a flourish. NASA's Solar Dynamics Observatory (SDO) caught the action in dramatic detail in extreme ultr...

232

Prediction of the far field noise from wind energy farms  

NASA Technical Reports Server (NTRS)

The basic physical factors involved in making predictions of wind turbine noise and an approach which allows for differences in the machines, the wind energy farm configurations and propagation conditions are reviewed. Example calculations to illustrate the sensitivity of the radiated noise to such variables as machine size, spacing and numbers, and such atmosphere variables as absorption and wind direction are presented. It is found that calculated far field distances to particular sound level contours are greater for lower values of atmospheric absorption, for a larger total number of machines, for additional rows of machines and for more powerful machines. At short and intermediate distances, higher sound pressure levels are calculated for closer machine spacings, for more powerful machines, for longer row lengths and for closer row spacings.

Shepherd, K. P.; Hubbard, H. H.

1986-01-01

233

Machine Learning  

NASA Astrophysics Data System (ADS)

The purpose of this chapter is to present fundamental ideas and techniques of machine learning suitable for the field of this book, i.e., for automated scientific discovery. The chapter focuses on those symbolic machine learning methods, which produce results that are suitable to be interpreted and understood by humans. This is particularly important in the context of automated scientific discovery as the scientific theories to be produced by machines are usually meant to be interpreted by humans. This chapter contains some of the most influential ideas and concepts in machine learning research to give the reader a basic insight into the field. After the introduction in Sect. 1, general ideas of how learning problems can be framed are given in Sect. 2. The section provides useful perspectives to better understand what learning algorithms actually do. Section 3 presents the Version space model which is an early learning algorithm as well as a conceptual framework, that provides important insight into the general mechanisms behind most learning algorithms. In section 4, a family of learning algorithms, the AQ family for learning classification rules is presented. The AQ family belongs to the early approaches in machine learning. The next, Sect. 5 presents the basic principles of decision tree learners. Decision tree learners belong to the most influential class of inductive learning algorithms today. Finally, a more recent group of learning systems are presented in Sect. 6, which learn relational concepts within the framework of logic programming. This is a particularly interesting group of learning systems since the framework allows also to incorporate background knowledge which may assist in generalisation. Section 7 discusses Association Rules - a technique that comes from the related field of Data mining. Section 8 presents the basic idea of the Naive Bayesian Classifier. While this is a very popular learning technique, the learning result is not well suited for human comprehension as it is essentially a large collection of probability values. In Sect. 9, we present a generic method for improving accuracy of a given learner by generatingmultiple classifiers using variations of the training data. While this works well in most cases, the resulting classifiers have significantly increased complexity and, hence, tend to destroy the human readability of the learning result that a single learner may produce. Section 10 contains a summary, mentions briefly other techniques not discussed in this chapter and presents outlook on the potential of machine learning in the future.

Hoffmann, Achim; Mahidadia, Ashesh

234

Filament overwrapped motor case technology  

NASA Astrophysics Data System (ADS)

Atlantic Research Corporation (ARC) joined with the French Societe Europeenne de Propulsion (SEP) to develop and deliver to the U.S. Navy a small quantity of composite filament wound rocket motors to demonstrate a manufacturing technique that was being applied at the two companies. It was perceived that the manufacturing technique could produce motors that would be light in weight, inexpensive to produce, and that had a good chance of meeting insensitive munitions (IM) requirements that were being formulated by the Navy in the early 1980s. Under subcontract to ARC, SEP designed, tested, and delivered 2.75-inch rocket motors to the U.S. Navy for IM tests that were conducted in 1989 at China Lake, California. The program was one of the first to be founded by Nunn Amendment money. The Government-to-Government program was sponsored by the Naval Air Systems Command and was monitored by the Naval Surface Warfare Center, Indian Head (NSWC-IH), Maryland. The motor propellant that was employed was a new, extruded composite formulation that was under development at the Naval Surface Warfare Center. The following paper describes the highlights of the program and gives the results of structural and ballistic static tests and insensitive munitions tests that were conducted on demonstration motors.

Compton, Joel P.

1993-11-01

235

Do filaments cross core "boundaries"?  

NASA Astrophysics Data System (ADS)

Thanks to extensive observations of the Perseus star-forming region, and the Barnard 5 (B5) star-forming core within it, we can study filamentary structure at scales from tens of pc down to to hundredths of pc using a wide variety of gas and dust tracers. Recently, in compositing Herschel dust emission maps of Perseus with GBT and JVLA maps of ammonia in B5, we noticed that the large scale (>1 pc) filaments that lead to the B5 core appear to continue across the "coherent core" boundary, right down into the sub 0.1 pc scales traced by ammonia. We find this result very surprising, since it suggests that the "core" is not as distinct from its filamentary surroundings as we--and current conventional wisdom--would have predicted. Numerical simulations on 1-10 pc scales typically create "sink" particles on scales small enough to correspond to our JVLA measurements. The new B5 results presented here should inspire new simulations which offer enough dynamic range to trace the morphology of self-gravitating, non-isothermal turbulence continuously from 10 to 0.01 pc scales, in order to see how, why, and how long filamentary structure is maintained across these scales.

Goodman, Alyssa A.; Chen, Hope; Pineda, Jaime E.; Offner, Stella

2015-01-01

236

Filamentation of terawatts lasers pulses on 100m atmospheric path  

NASA Astrophysics Data System (ADS)

The experimental results of the filamentation terawatt femtosecond Ti:Sapphire-laser along an atmospheric path of 100- m length atmospheric path using different spatial focusing and pulse power. The high efficiency of controlling the position and length of the filamentation zone using various spatial focusing are presented. The dependences of the length and position of the filamentation of the initial degree of focus and pulse power, number of filaments along the filamentation zone is determined. The data are compared to the length of the field and the number of filaments filamentation with the results of our earlier experiments.

Apeksimov, D. V.; Burnashov, A. V.; Zemlyanov, A. A.; Iglakova, A. N.; Kabanov, A. M.; Kuchinskaya, O. I.; Matvienko, G. G.; Oshlakov, V. K.; Petrov, A. V.

2014-11-01

237

Atomic model of the actin filament  

Microsoft Academic Search

The F-actin filament has been constructed from the atomic structure of the actin monomer to fit the observed X-ray fibre diagram from oriented gels of F-actin. A unique orientation of the monomer with respect to the actin helix has been found. The main interactions are along the two-start helix with a contribution from a loop extending across the filament axis

Kenneth C. Holmes; David Popp; Werner Gebhard; Wolfgang Kabsch

1990-01-01

238

Actin filament mechanics in the laser trap  

Microsoft Academic Search

Numerous biological processes, including muscular contraction, depend upon the mechanical properties of actin filaments. One\\u000a such property is resistance to bending (flexural rigidity, EI). To estimate EI, we attached the ends of fluorescently labelled\\u000a actin filaments to two microsphere‘handles’ captured in independent laser traps. The positions of the traps were manipulated\\u000a to apply a range of tensions (0--8 pN)to the

D. E. DUPUIS; W. H. GUILFORD; J. WU; D. M. WARSHAW

1997-01-01

239

Filament-wound, fiberglass cryogenic tank supports  

NASA Technical Reports Server (NTRS)

The design, fabrication, and testing of filament-wound, fiberglass cryogenic tank supports for a LH2 tank, a LF2/FLOX tank and a CH4 tank. These supports consist of filament-wound fiberglass tubes with titanium end fittings. These units were satisfactorily tested at cryogenic temperatures, thereby offering a design that can be reliably and economically produced in large or small quantities. The basic design concept is applicable to any situation where strong, lightweight axial load members are desired.

Carter, J. S.; Timberlake, T. E.

1971-01-01

240

State-Machine Replication  

E-print Network

State-Machine Replication #12;The Problem Clients Server #12;The Problem Clients Server #12;The (state machine) #12;The Solution 1. Make server deterministic (state machine) State machine #12;The Solution 1. Make server deterministic (state machine) 2. Replicate server State machines #12;The Solution 1

Venkataramani, Arun

241

Parametric evaluation of wind turbine noise  

SciTech Connect

In lieu of large single wind turbine installations, US Windpower, Burlington, Massachusetts is promoting the wind farm concept for wind power generation. A wind farm is an array of several small machines which are used to produce the equipment power of a single, large wind turbine. The smaller 50 KW machines manufactured by US Windpower, when used in an array to produce a large quantity of power, minimize the incidence of annoying infrasonic pulsing, nevertheless, the production of low frequency sound by wind farms still occurs. Measurements and theory clearly demonstrate that blade passage through the tower wake produces a sound pressure level frequency spectra consisting of harmonics of the blade passage frequency. The chief purpose of this work is to identify the importance of various tower and blade parameters that control blade passage noise generation.

Tocci, G.C.; Marcus, E.N.

1982-01-01

242

Simple Machines  

NSDL National Science Digital Library

Can you identify the six types of simple machines? 1. What do you know about Inclined Planes? Draw an example on your graphic organizer and state one fact.Inclined Plane 2. What do you know about levers? Draw an example on your graphic organizer and state one fact.Lever. 3. What do you know about pulleys? Draw an example on your graphic organizer and ...

Stewart, Miss

2010-03-24

243

Experimental study of filamentation in laser-plasma interactions  

SciTech Connect

The filamentation instability can lead to regions of increased laser intensity when a spatially nonuniform laser beam interacts with a plasma. An experimental technique will be described which identifies the density perturbation produced by filaments. The growth of filaments has been investigated and, when the laser intensity is large enough, the transverse density profile of the filament can be measured. Evidence of filament growth influenced by plasma flow and density gradients is presented. 19 refs., 4 figs.

Young, P.E.

1991-01-07

244

Solar filament impact on 21 January 2005: Geospace consequences  

NASA Astrophysics Data System (ADS)

21 January 2005, a moderate magnetic storm produced a number of anomalous features, some seen more typically during superstorms. The aim of this study is to establish the differences in the space environment from what we expect (and normally observe) for a storm of this intensity, which make it behave in some ways like a superstorm. The storm was driven by one of the fastest interplanetary coronal mass ejections in solar cycle 23, containing a piece of the dense erupting solar filament material. The momentum of the massive solar filament caused it to push its way through the flux rope as the interplanetary coronal mass ejection decelerated moving toward 1 AU creating the appearance of an eroded flux rope (see companion paper by Manchester et al. (2014)) and, in this case, limiting the intensity of the resulting geomagnetic storm. On impact, the solar filament further disrupted the partial ring current shielding in existence at the time, creating a brief superfountain in the equatorial ionosphere—an unusual occurrence for a moderate storm. Within 1 h after impact, a cold dense plasma sheet (CDPS) formed out of the filament material. As the interplanetary magnetic field (IMF) rotated from obliquely to more purely northward, the magnetotail transformed from an open to a closed configuration and the CDPS evolved from warmer to cooler temperatures. Plasma sheet densities reached tens per cubic centimeter along the flanks—high enough to inflate the magnetotail in the simulation under northward IMF conditions despite the cool temperatures. Observational evidence for this stretching was provided by a corresponding expansion and intensification of both the auroral oval and ring current precipitation zones linked to magnetotail stretching by field line curvature scattering. Strong Joule heating in the cusps, a by-product of the CDPS formation process, contributed to an equatorward neutral wind surge that reached low latitudes within 1-2 h and intensified the equatorial ionization anomaly. Understanding the geospace consequences of extremes in density and pressure is important because some of the largest and most damaging space weather events ever observed contained similar intervals of dense solar material.

Kozyra, J. U.; Liemohn, M. W.; Cattell, C.; De Zeeuw, D.; Escoubet, C. P.; Evans, D. S.; Fang, X.; Fok, M.-C.; Frey, H. U.; Gonzalez, W. D.; Hairston, M.; Heelis, R.; Lu, G.; Manchester, W. B.; Mende, S.; Paxton, L. J.; Rastaetter, L.; Ridley, A.; Sandanger, M.; Soraas, F.; Sotirelis, T.; Thomsen, M. W.; Tsurutani, B. T.; Verkhoglyadova, O.

2014-07-01

245

Wild Wind  

NSDL National Science Digital Library

Students learn the difference between global, prevailing and local winds. They make wind vanes out of paper, straws and soda bottles and use them to measure wind direction over time. They analyze their data to draw conclusions about the local prevailing winds.

Integrated Teaching And Learning Program

246

Fiberglass composite blades for the 4 MW - WTS-4 wind turbine  

NASA Astrophysics Data System (ADS)

The design and fabrication of composite blades for the WTS-4, a four-megawatt horizontal-axis wind turbine, is discussed. The blade consists of a two-cell, monolithic structure of filament-wound, fiberglass/epoxy composite. Filament winding is a low-cost process which can produce a blade with an aerodynamically efficient airfoil and planform with nonlinear twist to achieve high performance in terms of energy capture. Its retention provides a redundant attachment for long, durable life and safety. Advanced tooling concepts and as sophisticated computer control is used to achieve the unique filament-wound shape.

Bussolari, R. J.

247

[Phagoresistance of filamentous cyanobacteria clones].  

PubMed

The paper deals with formation regularities of phagoresistant clones of cyanobacteria in two productive virus-cell systems: heterocyst cyanobacterium Nostoc linckia--cyanophage N-2, and mutant in heterocysts strain of Anabaena variabilis--cyanophage A-1. Frequency of spontaneous formation of phagoresistant clones of cyanobacterium N. linckia varies within 1.0-8.0 x 10(-6) per a cell, A. variabilis--5.0 x 10(-6)-7.0 x 10(-7) per cell. All the studied phagoresistant clones of N. linckia have identical morpho-cultural properties and do not differ from those of the initial culture. Phagoresistant clones of A. variabilis are presented by two groups. One of them, as to its properties, does not practically differ from the wild type culture. The second group differs considerably from the initial culture A. variabilis as to a number of characteristics--time of colonies appearance, their amount, length of trichomas, specific rate of growth and biomass accumulation. Spontaneous transfer of cyanophages to the culture liquid of clones resistant forms of cyanobacteria has not been revealed. Lysis of cells of the studied clones also was not induced under the effect of mytomycin C, thermal treatment and UV-irradiation. Cyanophage N-2 is not adsorbed by the cells of resistant cloned forms of cyanobacteria N. linckia. Only nonspecific adsorption takes place on the cells of phage-resistant clones of A. variabilis of both groups: about 20% of virions introduced in the adsorption mixture. Basing on the data obtained, it is supposed that phage-resistance of stable clones of filamentous cyanobacteria under the conditions of the given experiment is determined by the structure modification of cells receptors. PMID:15104055

Mendzhul, M I; Lysenko, T G; Busakhina, I V; Shainskaia, O A

2004-01-01

248

National wind energy construction program: its energy and economic impact  

Microsoft Academic Search

Wind energy may be the most economical solar-electric technology. With an aggressive development program, electricity could be produced at costs below that of oil-fired electric plants. Key facts which support this optimism are: the wind reservoir is very large; the technology is proven; and megawatt-scale wind machines are available.

1980-01-01

249

Hot-filament-activated chemical-vapor deposition of carbon: Film growth and filament reactions  

SciTech Connect

Pure glassy carbon films [no x-ray photoelectron spectroscopy (XPS) detectable impurities above the 0.5% level] as thick as 25 000 A have been grown on nearby silicon substrates ([ital T][gt]100 [degree]C) as a result of reactions between a hot tungsten filament and cyclopentane. Above [similar to]2500 [degree]C, cyclopentane-tungsten reactions yield a liquid W/C eutectic which limits filament operation. Below [similar to]2500 [degree]C, resistance changes of the filament and XPS spectra show such reactions form carbides and graphite. It is shown that the temperature dependence of the carbon deposition rate is similar to the sublimation rate of carbon from graphite and tungsten carbide. Moreover, it is also shown that C[sub 1], C[sub 2], and C[sub 3] (carbon monomers, dimers, and trimers) are evaporated from carbarized tungsten and also from graphite. These results suggest that carbon film growth is a consequence of evaporation of carbon from the carbarized tungsten filament, with steady-state film deposition occurring as a result of a quasisteady state in the formation and decomposition of the carbarized tungsten. Carbarization of the tungsten filament is expected for a wide variety of hydrocarbon gases, but evaporation of C species from this carbarized filament should be independent of the way it is produced. These same processes should occur at the tungsten filament during diamond film deposition using the hot-filament chemical-vapor deposition method.

Rye, R.R. (Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States))

1994-07-15

250

Design and performance of the field regulated reluctance machine  

Microsoft Academic Search

A topological configuration for rotating electromagnetic machines that can produce significantly higher force density than an induction machine is investigated. The stator is constructed using full pitch concentrated windings embedded in conventional slots. Rotor saliency is produced using poles constructed of axially oriented laminations. Operation is such that all of the conductors are actively taking part in torque production all

Joseph D. Law; Allen Chertok; T.A. Lipo

1992-01-01

251

Design and performance of field regulated reluctance machine  

Microsoft Academic Search

A unique topological configuration for rotating electromagnetic machines that can produce significantly higher force density than an induction machine is investigated. The stator is constructed using full pitch concentrated windings embedded in conventional slots. Rotor saliency is produced using poles constructed of axially oriented laminations. Operation is such that all of the conductors are actively taking part in torque production

J. D. Law; A. Chertok; T.A. Lipo

1994-01-01

252

Rotor loss in permanent magnet brushless AC machines  

Microsoft Academic Search

The eddy current loss in the permanent magnets of brushless AC machines is usually neglected, since the fundamental airgap field rotates in synchronism with the rotor and time harmonics in the current waveform and space harmonics in the winding distribution are generally small. However, machine designs are emerging for which the fundamental component of the stator MMF has fewer poles

K. Atallah; D. Howe; P. H. Mellor; D. A. Stone

1999-01-01

253

Rotor loss in permanent-magnet brushless AC machines  

Microsoft Academic Search

The eddy-current loss in the permanent magnets of brushless AC machines is usually neglected, since the fundamental air-gap field usually rotates in synchronism with the rotor, and time harmonics in the current waveform and space harmonics in the winding distribution are generally small. However, an important category of brushless AC machine design is emerging in which the fundamental component of

Kais Atallah; David Howe; Philip H. Mellor; David A. Stone

2000-01-01

254

Control of variable speed wind energy conversion system using a wind speed sensorless optimum speed MPPT control method  

Microsoft Academic Search

This paper presents a wind speed sensorless maximum power point tracking (MPPT) controller for variable speed wind energy conversion systems (WECS). The proposed controller generates at its output the optimum speed (OS) command for the speed control loop of the vector controlled machine side converter control system without requiring the knowledge of wind speed. The MPPT control of the WECS

J. S. Thongam; P. Bouchard; R. Beguenane; A. F. Okou; A. Merabet

2011-01-01

255

Overview of Stator-Permanent Magnet Brushless Machines  

Microsoft Academic Search

Permanent magnet (PM) brushless machines having magnets and windings in stator (the so-called stator-PM machines) have attracted more and more attention in the past decade due to its definite advantages of robust structure, high power density, high efficiency, etc. In this paper, an overview of the stator-PM ma- chine is presented, with particular emphasis on concepts, opera- tion principles, machine

Ming Cheng; Wei Hua; Jianzhong Zhang; Wenxiang Zhao

2011-01-01

256

Machine Design  

NSDL National Science Digital Library

This website, the homepage of Machine Design.com, contains resources on a variety of information for engineers and technicians related to devices, components, design applications, products, and systems in the manufacturing technology sector. The site also features a CAD library, eBooks, audiovisual aids, webinars, whitepapers and a reference center. Some of the resources require a free login. The page offers an RSS feed to keep users up to date on new resources. A free login may be required to access some of these items.

257

On the nature of star-forming filaments - I. Filament morphologies  

NASA Astrophysics Data System (ADS)

We use a suite of high-resolution molecular cloud simulations carried out with the moving mesh code AREPO to explore the nature of star-forming filaments. The simulated filaments are identified and categorized from column density maps in the same manner as for recent Herschel observations. When fitted with a Plummer-like profile, the filaments are in excellent agreement with observations, and have shallow power-law profiles of p ˜ 2.2 without the need for magnetic support. When data within 1 pc of the filament centre are fitted with a Gaussian function, the average full width at half-maximum (FWHM) is ˜0.3 pc, in agreement with predictions for accreting filaments. However, if the fit is constructed using only the inner regions, as in Herschel observations, the resulting FWHM is only ˜0.2 pc. This value is larger than that measured in IC 5146 and Taurus, but is similar to that found in the Planck Galactic cold cores and in Cygnus X. The simulated filaments have a range of widths rather than a constant value. When the column density maps are compared to the 3D gas densities, the filaments seen in column density do not belong to a single structure. Instead, they are made up of a network of short ribbon-like sub-filaments reminiscent of those seen in Taurus. The sub-filaments are pre-existing within the simulated clouds, have radii similar to their Jeans radius, and are not primarily formed through fragmentation of the larger filament seen in column density. Instead, small filamentary clumps are swept together into a single column density structure by the large-scale collapse of the cloud.

Smith, Rowan J.; Glover, Simon C. O.; Klessen, Ralf. S.

2014-12-01

258

Superconductors in large synchronous machines. Final report  

Microsoft Academic Search

Research progress from the continuing program to apply superconductors in the field windings of large synchronous machines is reported for the eleven month contract period. The background of the project since 1969 is briefly reviewed. The general conclusion is that large superconducting turbogenerators are feasible and that the projected advantages should be realizable. Contractual details and a list of contributors

J. L. Jr

1976-01-01

259

Tubular actin filaments in tobacco guard cells.  

PubMed

The dynamic remodeling of actin filaments in guard cells functions in stomatal movement regulation. In our previous study, we found that the stochastic dynamics of guard cell actin filaments play a role in chloroplast movement during stomatal movement. In our present study, we further find that tubular actin filaments are present in tobacco guard cells that express GFP-mouse talin; approximately 2.3 tubular structures per cell with a diameter and height in the range of 1-3 µm and 3-5 µm, respectively. Most of the tubular structures were found to be localized in the cytoplasm near the inner walls of the guard cells. Moreover, the tubular actin filaments altered their localization slowly in the guard cells of static stoma, but showed obvious remodeling, such as breakdown and re-formation, in moving guard cells. Tubular actin filaments were further found to be colocalized with the chloroplasts in guard cells, but their roles in stomatal movement regulation requires further investigation.  PMID:21921692

Chu, Cui-Ping; Liu, Zhao-Hua; Hu, Zi-Ying; Wang, Xiu-Ling

2011-10-01

260

Kinetics of Filament Bundling with Attractive Interactions  

PubMed Central

We study the kinetics of filament bundling by variable time-step Brownian-dynamics simulations employing a simplified attractive potential based on earlier atomic-level calculations for actin filaments. Our results show that collisions often cluster in time, due to memory in the random walk. The clustering increases the bundling opportunities. Small-angle collisions and collisions with short center-to-center distance are more likely to lead to bundling. Increasing the monomer-monomer attraction decreases the bundling time to a diffusional limit, which is determined by the capture cross-section and diffusion coefficients. The simulations clearly show that the bundling process consists of two sequential phases: rotation, by which two filaments align parallel to each other; and sliding, by which they maximize their contact length. Whether two filaments bundle or not is determined by the competition between rotation to a parallel state and escape. Increasing the rotational diffusion coefficient and attraction enhances rotation; decreasing attraction and increasing the translational diffusion coefficients enhance escape. Because of several competing effects, the filament length only affects the bundling time weakly. PMID:15377526

Yu, Xueping; Carlsson, A. E.

2004-01-01

261

Eruption of a Bifurcated Solar Filament  

NASA Astrophysics Data System (ADS)

We study the partial eruption of a solar filament observed by the Solar Dynamics Observatory (SDO) and the Solar TErrestrial RElations Observatory-Ahead (STEREO-A) spacecraft on 9 May 2012. This filament was located in Active Region NOAA 11475 and consisted of two distinct branches, separated in height above the active region's primary polarity-inversion line. For two days prior to the filament eruption, several threads of filament material were observed to connect the lower branch to the upper branch with evidence of a transfer of mass along them. The eruption commenced as a slow rise of the upper branch that began at 9 May 2012 23:40 UT, with the main eruption occurring half an hour later, producing a coronal mass ejection (CME). During the eruption, the upper branch was observed to rotate approximately 120 degrees in a counter-clockwise direction. We suggest that the mass transfer events also comprised a transfer of magnetic flux that led the upper branch of the filament to lose equilibrium as a result of a helical kink instability or torus instability.

Zhu, Chunming; Alexander, David

2014-01-01

262

Eruption of a Bifurcated Solar Filament  

NASA Astrophysics Data System (ADS)

We study the partial eruption of a solar filament observed by the SDO and the STEREO-A spacecraft on 9 May 2012. This filament was located in active region NOAA 11475, and consisted of two distinct branches, separated in height above the active region's primary polarity-inversion line. For two days prior to the filament eruption, several threads of filament material were observed to connect the lower branch to the upper branch with evidence of a transfer of mass along them. The eruption commenced as a slow rise of the upper branch that began at 9 May 2012 23:40 UT, with the main eruption occurring half an hour later, producing a coronal mass ejection (CME). During the eruption, the upper branch was observed to rotate approximately 120 degrees in a counter-clockwise direction. We suggest that the mass transfer events also comprised a transfer of magnetic flux that led the upper branch of the filament to lose equilibrium as a result of a helical kink instability or torus instability.

Zhu, Chunming; Alexander, D.

2013-07-01

263

SYMPATHETIC FILAMENT ERUPTIONS CONNECTED BY CORONAL DIMMINGS  

SciTech Connect

We present for the first time detailed observations of three successive, interdependent filament eruptions that occurred one by one within 5 hr from different locations beyond the range of a single active region. The first eruption was observed from an active region and was associated with a coronal mass ejection (CME), during which diffuse and complex coronal dimmings formed, largely extending to the two other filaments located in quiet-Sun regions. Then, both quiescent filaments consecutively underwent the second and third eruptions, while the nearby dimmings were persistent. Comparing the result of a derived coronal magnetic configuration, the magnetic connectivity between the dimmings suggested that they were caused by the joint effect of simple expansion of overlying loop systems forced by the first eruption, as well as by its erupting field interacting or reconnecting with the surrounding magnetic structures. Note that the dimming process in the first eruption indicated a weakening and partial removal of an overlying magnetic field constraint on the two other filaments, and thus one can physically connect these eruptions as sympathetic. It appears that the peculiar magnetic field configuration in our event was largely favorable to the occurrence of sympathetic filament eruptions. Because coronal dimmings are frequent and common phenomena in solar eruptions, especially in CME events, it is very likely that they represent a universal agent that can link consecutive eruptions nearby with sympathetic eruptions.

Jiang Yunchun; Yang Jiayan; Hong Junchao; Bi Yi; Zheng Ruisheng, E-mail: jyc@ynao.ac.cn [National Astronomical Observatories/Yunnan Astronomical Observatory, Chinese Academy of Sciences, P.O. Box 110, Kunming 650011 (China)

2011-09-10

264

?-Helical architecture of cytoskeletal bactofilin filaments revealed by solid-state NMR.  

PubMed

Bactofilins are a widespread class of bacterial filament-forming proteins, which serve as cytoskeletal scaffolds in various cellular pathways. They are characterized by a conserved architecture, featuring a central conserved domain (DUF583) that is flanked by variable terminal regions. Here, we present a detailed investigation of bactofilin filaments from Caulobacter crescentus by high-resolution solid-state NMR spectroscopy. De novo sequential resonance assignments were obtained for residues Ala39 to Phe137, spanning the conserved DUF583 domain. Analysis of the secondary chemical shifts shows that this core region adopts predominantly ?-sheet secondary structure. Mutational studies of conserved hydrophobic residues located in the identified ?-strand segments suggest that bactofilin folding and polymerization is mediated by an extensive and redundant network of hydrophobic interactions, consistent with the high intrinsic stability of bactofilin polymers. Transmission electron microscopy revealed a propensity of bactofilin to form filament bundles as well as sheet-like, 2D crystalline assemblies, which may represent the supramolecular arrangement of bactofilin in the native context. Based on the diffraction pattern of these 2D crystalline assemblies, scanning transmission electron microscopy measurements of the mass per length of BacA filaments, and the distribution of ?-strand segments identified by solid-state NMR, we propose that the DUF583 domain adopts a ?-helical architecture, in which 18 ?-strand segments are arranged in six consecutive windings of a ?-helix. PMID:25550503

Vasa, Suresh; Lin, Lin; Shi, Chaowei; Habenstein, Birgit; Riedel, Dietmar; Kühn, Juliane; Thanbichler, Martin; Lange, Adam

2015-01-13

265

Tunneling machine  

SciTech Connect

A diametrically compact tunneling machine for boring tunnels is disclosed. The machine includes a tubular support frame having a hollow piston mounted therein which is movable from a retracted position in the support frame to an extended position. A drive shaft is rotatably mounted in the hollow piston and carries a cutter head at one end. The hollow piston is restrained against rotational movement relative to the support frame and the drive shaft is constrained against longitudinal movement relative to the hollow piston. A plurality of radially extendible feet project from the support frame to the tunnel wall to grip the tunnel wall during a tunneling operation wherein the hollow piston is driven forwardly so that the cutter head works on the tunnel face. When the hollow piston is fully extended, a plurality of extendible support feet, which are fixed to the rearward and forward ends of the hollow piston, are extended, the radially extendible feet are retracted and the support frame is shifted forwardly by the piston so that a further tunneling operation may be initiated.

Snyder, L.L.

1980-02-19

266

Propagation of terahertz wave inside femtosecond laser filament in air  

NASA Astrophysics Data System (ADS)

Terahertz (THz) generation in femtosecond laser filament has recently been found to greatly expand THz applications in atmospheric remote sensing. In this article, by investigating the THz waveform emitted from different length of filaments, the refractive index of the THz wave has been found to be smaller than the unity within the filament region. It indicates that the THz pulse may propagate inside the filament though the diameter of the filament is much smaller than the wavelength of the THz wave. The hypothesis is supported by further numerical simulation, which considers the radially non-uniform plasma density distribution of the filament.

Zhao, Jiayu; Zhang, Yizhu; Wang, Zhi; Chu, Wei; Zeng, Bin; Liu, Weiwei; Cheng, Ya; Xu, Zhizhan

2014-09-01

267

Course info Machine Learning  

E-print Network

Course info Machine Learning Real life problems Lecture 1: Machine Learning Problem Qinfeng (Javen) Shi 28 July 2014 Intro. to Stats. Machine Learning COMP SCI 4401/7401 Qinfeng (Javen) Shi Lecture 1: Machine Learning Problem #12;Course info Machine Learning Real life problems Table of Contents I 1 Course

Shi, Qinfeng "Javen"

268

Enertech 2-kW high-reliability wind system. Phase II. Fabrication and testing  

SciTech Connect

A high-reliability wind machine rated for 2 kW in a 9 m/s wind has been developed. Activities are summarized that are centered on the fabrication and testing of prototypes of the wind machine. The test results verified that the wind machine met the power output specification and that the variable-pitch rotor effectively controlled the rotor speed for wind speeds up to 50 mph. Three prototypes of the wind machine were shipped to the Rocky Flats test center in September through November of 1979. Work was also performed to reduce the start-up wind speed. The start-up wind speed to the Enertech facility has been reduced to 4.5 m/s.

Cordes, J A; Johnson, B A

1981-06-01

269

Design, evaluation, and fabrication of low-cost composite blades for intermediate-size wind turbines  

SciTech Connect

The low-cost composite blade program is described, involving design, evaluation and fabrication of a pair of low-cost composite rotor blades (LCCB) for the MOD-0A wind turbine. The objectives of the program were to identify low cost approaches to the design and fabrication of blades for a two-bladed 200 kW wind turbine and to assess the applicability of the techniques to larger and smaller blades. In Phase I of the program, several blade designs were developed to the point where reasonably accurate estimates could be made of the structural properties and costs of tooling and fabrication. The most cost-effective design was selected for detailed design in Phase II. Structural analysis of the selected design was performed, with assistance from NASA in some of the more specialized techniques (e.g. flutter analysis). Subelement and subscale specimens were fabricated in Phase I for testing. Blade tooling was designed and fabricated. Major items included a 60 ft D-spar mandrel and its supports, a 60 ft cure oven with a 200 kW heater, and a transverse filament tape (TFT) pre-impregnation station. Two complete blades and a partial blade for tool tryout were built. A 100 ft long ring-winder machine was designed and built.

Weingart, O.

1981-09-01

270

Filament Twist in F-Actin Bundles  

NASA Astrophysics Data System (ADS)

The twist state of F-actin can modify specific binding sites and influence the hierarchy of interactions in cytoskeletal regulation. F-actin in the cytoskeleton is often organized into bundles, using a wide variety of cationic molecules and actin-linking proteins. The native helical symmetry of uncondensed f-actin filaments is not necessarily the preferred symmetry of bundled filaments, which will depend on the particular bundling mechanism and the kind of condensing agent used. In order to explore the role of filament distortion in the process of bundle formation, we have carried out a series of synchrotron x-ray measurements on systems of bundled f-actin, using multivalent cations, cationic globular proteins, and actin binding proteins. Preliminary results will be presented. This work was supported by NSF DMR-0071761, DOE, DEFG02-91ER45439, the Beckman Young Investigator Program, and the Cystic Fibrosis Foundation.

Angelini, Tommy; Sanders, Lori; Wong, Gerard

2003-03-01

271

Electrical Characterization of Femtosecond Laser Filaments  

NASA Astrophysics Data System (ADS)

The propagation of intense femtosecond laser pulses in air has been the subject of considerable interest during the last few years. Intense laser filaments tend to form due to the dynamical balance between nonlinear (Kerr) focusing and ionization-driven plasma defocusing. Laser filaments with diameters of 200 ?m will propagate over many meters with intensities of 10^13 W/cm^2. These filaments can provide the conducting path to initiate laser-guided electrical discharges [1]. The present experiment uses a mini-Marx generator to provide a 120-kV pulse as the laser (50 fsec, 40 mJ) forms a preferred conducting path to ground. The set-up is used to characterize the resistivity of the conducting channel. [1] D. Gordon et al., Phys. of Plasmas, vol. 10, no. 11, p. 4530, Nov. 2003.

Fischer, R. P.; Ting, A.; Gordon, D.; Briscoe, E.; Sprangle, P.; Baronavski, A. P.; Ladouceur, H. D.; Girardi, P. G.

2004-11-01

272

Activated carbon filaments with mainly mesopores  

SciTech Connect

Activated carbon filaments of diameter {approximately} 0.1 {micro}m, mean pore size (BJH) 65 {angstrom}, specific surface area 1,540 m{sup 2}/g and burn-off 64% (yield 36%) were obtained by activating carbon filaments of diameter {approximately} 0.1 {micro}m in CO{sub 2} + N{sub 2} (1:1) at 970 C for100 min. Prior to this activation, the filaments were surface oxidized by exposure to ozone (0.3 vol.% in air) at 150 C for 3 min. Other than being used as adsorbents for purification and chemical processing, activated carbon materials are used as catalytic materials, battery electrode materials and biomedical engineering materials.

Lu, W.; Chung, D.D.L. [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.

1996-12-31

273

SOLAR MAGNETIZED 'TORNADOES': RELATION TO FILAMENTS  

SciTech Connect

Solar magnetized 'tornadoes', a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but are rooted in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized plasma and therefore differ distinctly from terrestrial tornadoes. Here we report the first analysis of solar 'tornadoes' (two papers which focused on different aspects of solar tornadoes were published in the Astrophysical Journal Letters and Nature, respectively, during the revision of this Letter). A detailed case study of two events indicates that they are rotating vertical magnetic structures probably driven by underlying vortex flows in the photosphere. They usually exist as a group and are related to filaments/prominences, another important solar phenomenon whose formation and eruption are still mysteries. Solar tornadoes may play a distinct role in the supply of mass and twists to filaments. These findings could lead to a new explanation of filament formation and eruption.

Su Yang; Veronig, Astrid; Temmer, Manuela [IGAM-Kanzelhoehe Observatory, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Wang Tongjiang [Department of Physics, Catholic University of America, Washington, DC 20064 (United States); Gan Weiqun, E-mail: yang.su@uni-graz.at [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

2012-09-10

274

Wind speed sensorless maximum power point tracking control of variable speed wind energy conversion systems  

Microsoft Academic Search

A maximum power point tracking (MPPT) controller for variable speed wind energy conversion system (WECS) is proposed. The proposed method, without requiring the knowledge of wind speed, air density or turbine parameters, generates at its output the optimum speed command for speed control loop of rotor flux oriented vector controlled machine side converter control system using only the instantaneous active

J. S. Thongam; P. Bouchard; H. Ezzaidi; M. Ouhrouche

2009-01-01

275

Comparative performance of open and totally enclosed machines  

SciTech Connect

Continuous improvements in insulating materials, manufacturing consistencies in sealed windings, and extensive laboratory testing of various systems show that synchronous machines with NEMA II construction can replace totally enclosed machines. Tests on windings in corrosive atmosphere show that sealed insulation systems are impervious to the environment. Standard maintenance ensures that incendive arcing will not be generated in potentially hazardous environments. When compared to totally enclosed machines, the NEMA II type construction is lighter, more efficient, has lower short circuit current and associated torques, and is easier to maintain.

Mesrobian, A.; Hudson, J.A. [Reliance Electric, Mankato, MN (United States). Kato Engineering Div.

1995-12-31

276

Filamentary structures in dense plasma focus: Current filaments or vortex filaments?  

SciTech Connect

Recent observations of an azimuthally distributed array of sub-millimeter size sources of fusion protons and correlation between extreme ultraviolet (XUV) images of filaments with neutron yield in PF-1000 plasma focus have re-kindled interest in their significance. These filaments have been described variously in literature as current filaments and vortex filaments, with very little experimental evidence in support of either nomenclature. This paper provides, for the first time, experimental observations of filaments on a table-top plasma focus device using three techniques: framing photography of visible self-luminosity from the plasma, schlieren photography, and interferometry. Quantitative evaluation of density profile of filaments from interferometry reveals that their radius closely agrees with the collision-less ion skin depth. This is a signature of relaxed state of a Hall fluid, which has significant mass flow with equipartition between kinetic and magnetic energy, supporting the “vortex filament” description. This interpretation is consistent with empirical evidence of an efficient energy concentration mechanism inferred from nuclear reaction yields.

Soto, Leopoldo, E-mail: lsoto@cchen.cl; Pavez, Cristian; Moreno, José [Comisión Chilena de Energía Nuclear, CCHEN, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4, Departamento de Ciencias Físicas, Facultad de Ciencias Exactas, Universidad Andrés Bello, República 220, Santiago (Chile); Castillo, Fermin [Universidad Nacional Autónoma de México, Cuernavaca, México (Mexico); Veloso, Felipe [Instituto de Física, Pontificia Universidad Católica de Chile, 7820436 Santiago (Chile); Auluck, S. K. H. [Bhabha Atomic Research Center, Mumbai 400 085 (India)

2014-07-15

277

Hybrid-secondary uncluttered induction machine  

DOEpatents

An uncluttered secondary induction machine (100) includes an uncluttered rotating transformer (66) which is mounted on the same shaft as the rotor (73) of the induction machine. Current in the rotor (73) is electrically connected to current in the rotor winding (67) of the transformer, which is not electrically connected to, but is magnetically coupled to, a stator secondary winding (40). The stator secondary winding (40) is alternately connected to an effective resistance (41), an AC source inverter (42) or a magnetic switch (43) to provide a cost effective slip-energy-controlled, adjustable speed, induction motor that operates over a wide speed range from below synchronous speed to above synchronous speed based on the AC line frequency fed to the stator.

Hsu, John S. (Oak Ridge, TN)

2001-01-01

278

Modular Permanent Magnet Machine Based on Soft Magnetic *** Burgess-Norton Mfg.Co.  

E-print Network

2005-30 Modular Permanent Magnet Machine Based on Soft Magnetic Composite *** Burgess-Norton Mfg magnetic composite (SMC) material, electric machine design is no longer limited to the traditional iron system based on a novel multi phase modular permanent magnet machine is proposed. The concentric winding

Lipo, Thomas

279

Structure of Flexible Filamentous Plant Viruses  

SciTech Connect

Flexible filamentous viruses make up a large fraction of the known plant viruses, but in comparison with those of other viruses, very little is known about their structures. We have used fiber diffraction, cryo-electron microscopy, and scanning transmission electron microscopy to determine the symmetry of a potyvirus, soybean mosaic virus; to confirm the symmetry of a potexvirus, potato virus X; and to determine the low-resolution structures of both viruses. We conclude that these viruses and, by implication, most or all flexible filamentous plant viruses share a common coat protein fold and helical symmetry, with slightly less than 9 subunits per helical turn.

Kendall, Amy; McDonald, Michele; Bian, Wen; Bowles, Timothy; Baumgarten, Sarah C.; Shi, Jian; Stewart, Phoebe L.; Bullitt, Esther; Gore, David; Irving, Thomas C.; Havens, Wendy M.; Ghabrial, Said A.; Wall, Joseph S.; Stubbs, Gerald (IIT); (BU-M); (Vanderbilt); (Kentucky); (BNL)

2008-10-23

280

Current Filamentation Instability in Laser Wakefield Accelerators  

SciTech Connect

Experiments using an electron beam produced by laser-wakefield acceleration have shown that varying the overall beam-plasma interaction length results in current filamentation at lengths that exceed the laser depletion length in the plasma. Three-dimensional simulations show this to be a combination of hosing, beam erosion, and filamentation of the decelerated beam. This work suggests the ability to perform scaled experiments of astrophysical instabilities. Additionally, understanding the processes involved with electron beam propagation is essential to the development of wakefield accelerator applications.

Huntington, C. M.; Drake, R. P. [Atmospheric, Oceanic and Space Science, University of Michigan, Ann Arbor, Michigan, 48103 (United States); Thomas, A. G. R.; McGuffey, C.; Matsuoka, T.; Chvykov, V.; Kalintchenko, G.; Yanovsky, V.; Maksimchuk, A.; Krushelnick, K. [Center for Ultrafast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Kneip, S.; Najmudin, Z.; Palmer, C. [Blackett Laboratory, Imperial College London, London, SW7 2BZ (United Kingdom); Katsouleas, T. [Platt School of Engineering, Duke University, Durham, North Carolina, 27708 (United States)

2011-03-11

281

Cores, Filaments, and Bundles: Hierarchical core formation in the B213 filament in Taurus  

NASA Astrophysics Data System (ADS)

Characterizing the dense core formation in filaments is a critical step for our understanding of the star formation process within molecular clouds. Using different molecular tracers to study the gas kinematics at different scales and density regimes, we have investigated the dense core formation in the B213/L1495 filament in Taurus, one of the most prominent structures identified in nearby clouds (see Hacar et al 2013, A&A, 554, A55). Our analysis of its internal kinematics demonstrates that this filament is actually a bundle of 35 velocity-coherent filaments, typically with lengths of ˜ 0.5 pc and oscillatory-like and sonic velocity field, each of them exhibiting linear masses close to the expected mass for a filament in hydrostatic equilibrium. Among them, only a small fraction of these filaments (˜1/4) are "fertile" and efficiently fragment forming all the cores identified within this region, while most of them (˜3/4) do not form cores and remain "sterile". Our observations then suggest that core formation in Taurus occurs in two steps. First, 0.5 pc-long velocity-coherent filaments condense out of the cloud gas, probably as a result of the turbulent cascade. After that, the dense cores condense quasi-statically in only those "fertile" filaments that have accumulated enough mass to became gravitational unstable, inheriting their kinematic properties. The formation of these velocity-coherent filaments appears therefore as a critical step on the star formation process being the first subsonic structures formed out of the turbulent regime that dominates the cloud dynamics at large scales.

Hacar, Alvaro; Tafalla, Mario; Kauffmann, Jens; Kovacs, Attila

2013-07-01

282

Myosin binding protein-C activates thin filaments and inhibits thick filaments in heart muscle cells  

PubMed Central

Myosin binding protein-C (MyBP-C) is a key regulatory protein in heart muscle, and mutations in the MYBPC3 gene are frequently associated with cardiomyopathy. However, the mechanism of action of MyBP-C remains poorly understood, and both activating and inhibitory effects of MyBP-C on contractility have been reported. To clarify the function of the regulatory N-terminal domains of MyBP-C, we determined their effects on the structure of thick (myosin-containing) and thin (actin-containing) filaments in intact sarcomeres of heart muscle. We used fluorescent probes on troponin C in the thin filaments and on myosin regulatory light chain in the thick filaments to monitor structural changes associated with activation of demembranated trabeculae from rat ventricle by the C1mC2 region of rat MyBP-C. C1mC2 induced larger structural changes in thin filaments than calcium activation, and these were still present when active force was blocked with blebbistatin, showing that C1mC2 directly activates the thin filaments. In contrast, structural changes in thick filaments induced by C1mC2 were smaller than those associated with calcium activation and were abolished or reversed by blebbistatin. Low concentrations of C1mC2 did not affect resting force but increased calcium sensitivity and reduced cooperativity of force and structural changes in both thin and thick filaments. These results show that the N-terminal region of MyBP-C stabilizes the ON state of thin filaments and the OFF state of thick filaments and lead to a novel hypothesis for the physiological role of MyBP-C in the regulation of cardiac contractility. PMID:25512492

Kampourakis, Thomas; Yan, Ziqian; Gautel, Mathias; Sun, Yin-Biao; Irving, Malcolm

2014-01-01

283

Socially guided machine learning  

E-print Network

Social interaction will be key to enabling robots and machines in general to learn new tasks from ordinary people (not experts in robotics or machine learning). Everyday people who need to teach their machines new things ...

Thomaz, Andrea Lockerd

2006-01-01

284

Toasty Wind  

NSDL National Science Digital Library

In this quick activity, learners use a toaster to investigate the source for the Earth's wind. Learners hold a pinwheel above a toaster to discover that rising heat causes wind. Use this activity to introduce learners to the process of convection as a source for wind. This resource also explains how convection causes thunderstorms and lists important thunderstorm safety tips.

Service, National W.

2012-07-24

285

Ultrasonic evaluation of mechanical properties of thick, multilayered, filament wound composites  

NASA Technical Reports Server (NTRS)

A preliminary investigation is conducted to define capabilities and limitations of ultrasonic and acousto-ultrasonic measurements related to mechanical properties of filament wound graphite/epoxy composite structures. The structures studied are segments of filament wound cylinders formed of multiple layers of hoop and helical windings. The segments consist of 24 to 35 layers and range from 3.02 to 3.34 cm in wall thickness. The resultant structures are anisotropic, heterogeneous, porous, and highly attenuating to ultrasonic frequencies greater than 1 MHz. The segments represent structures to be used for space shuttle booster cases. Ultrasonic velocity and acousto-ultrasonic stress wave factor measurement approaches are discussed. Correlations among velocity, density, and porosity, and between the acousto-ultrasonic stress wave factor and interlaminar shear strength are presented.

Kautz, H. E.

1985-01-01

286

Residual stress analysis in forming process of filament wound thick-walled CFRP pipes  

SciTech Connect

Residual stress analysis for the cracking phenomenon of filament would thick-walled CFRP pipes, which frequently occurs in the forming process of curing and thermal cycling through the course of the wet filament winding, was made from both the experimental and theoretical points of view. A simple analytical model to study the cracking in the CFRP pipes was proposed. The pipes are multilayered and reinforced in the axial and circumferential directions alternatively by carbon fibers. Taking account of the anisotropy of mechanical and thermal properties including the shrinkage strain, which depend considerably on the temperature, the residual stresses in the CFRP pipes were elucidated in the forming process, particularly, in cooling of the cure process.

Kondo, Toshimi [Nagaoka College of Technology (Japan). Dept. of Mechanical Engineering; Sekine, Hideki [Tohoku Univ., Sendai (Japan). Dept. of Aeronautics and Space Engineering; Nakano, Kunio [Japan Space Utilization Center, Tokyo (Japan)

1995-11-01

287

Dynamics of filament formation in a Kerr medium  

SciTech Connect

We have studied the large-scale beam breakup and filamentation of femtosecond pulses in a Kerr medium. We have experimentally monitored the formation of stable light filaments, conical emission, and interactions between filaments. Three major stages lead to the formation of stable light filaments: First the beam breaks up into a pattern of connected lines (constellation), then filaments form on the constellations, and finally the filaments release a fraction of their energy through conical emission. We observed a phase transition to a faster filamentation rate at the onset of conical emission. We attribute this to the interaction of conical emissions with the constellation which creates additional filaments. Numerical simulations show good agreement with the experimental results.

Centurion, Martin [Physics Department, California Institute of Technology, Pasadena, California 91125 (United States); Pu Ye; Tsang, Mankei; Psaltis, Demetri [Department of Electrical Engineering, California Institute of Technology, Pasadena, California 91125 (United States)

2005-06-15

288

One Half Million Mile Solar Filament - Duration: 0:19.  

NASA Video Gallery

NASAâ??s Solar Dynamics Observatory (SDO) captures a very long, whip-like solar filament extending over half a million miles in a long arc above the sunâ??s surface. Filaments are cooler clouds of ...

289

Turing Machines A Turing machine M is  

E-print Network

to perform computations. A function f is Turing-computable iff there exists some TM M such that f(x) = y iff1 Turing Machines A Turing machine M is: Q, a set of internal states. , the input alphabet. , tape of Turing machine M on input w Initial state q0, tape w, blanks around w, read-write head at first symbol

Bylander, Tom

290

SMART Observation of Magnetic Helicity in Solar Filaments  

NASA Astrophysics Data System (ADS)

We examined the magnetic helicity of solar filaments from their structure in the chromosphere and corona. The H-alpha telescope of the Solar Magnetic Activity Research Telescope (SMART) observed 239 intermediate filaments from 2005 July 1 to 2006 May 15. The intermediate filament usually locates between two active regions. Using these images, we identified the filament spine and its barbs, and determined the chromospheric filament helicity from the mean angle between each barbs and a spine. We found that 71% (78 of 110) of intermediate filaments in the northern hemisphere are negative helicity and 67% (87 of 129) of filaments in the southern hemisphere are positive, which agreed with the well-known hemispheric tendency of the magnetic helicity. Additionally, we studied the coronal helicity of intermediate filaments. The coronal filament helicity is defined as the crossing angle of threads formed a filament. The helicity pattern of coronal filaments obtained with EIT/SOHO 171A also shows the helicity hemispheric tendency. Namely, 65% (71 of 110) of coronal filaments in the northern hemisphere exhibit negative helicity and the 65% (84 of 129) of filaments in the southern hemisphere show negative helicity. These data were observed in the same day with the SMART H-alpha data. Moreover, we found 12 filament eruptions in our data. The 7 of 12 filaments show the clear opposite sign of the hemispheric tendency of the magnetic helicity. The helicity seems to be change during temporal evolution. This results suggest that filament instability may be driven by the opposite sign helicity injection from the foot point of the barb.

Hagino, M.; Kitai, R.; Shibata, K.

2006-08-01

291

Magnetic field strength of active region filaments  

NASA Astrophysics Data System (ADS)

Aims: We study the vector magnetic field of a filament observed over a compact active region neutral line. Methods: Spectropolarimetric data acquired with TIP-II (VTT, Tenerife, Spain) of the 10 830 Å spectral region provide full Stokes vectors that were analyzed using three different methods: magnetograph analysis, Milne-Eddington inversions, and PCA-based atomic polarization inversions. Results: The inferred magnetic field strengths in the filament are around 600-700 G by all these three methods. Longitudinal fields are found in the range of 100-200 G whereas the transverse components become dominant, with fields as high as 500-600 G. We find strong transverse fields near the neutral line also at photospheric levels. Conclusions: Our analysis indicates that strong (higher than 500 G, but below kG) transverse magnetic fields are present in active region filaments. This corresponds to the highest field strengths reliably measured in these structures. The profiles of the helium 10 830 Å lines observed in this active region filament are dominated by the Zeeman effect.

Kuckein, C.; Centeno, R.; Martínez Pillet, V.; Casini, R.; Manso Sainz, R.; Shimizu, T.

2009-07-01

292

Radial interchange motions of plasma filaments  

SciTech Connect

Radial convection of isolated filamentary structures due to interchange motions in magnetized plasmas is investigated. Following a basic discussion of vorticity generation, ballooning, and the role of sheaths, a two-field interchange model is studied by means of numerical simulations on a biperiodic domain perpendicular to the magnetic field. It is demonstrated that a blob-like plasma structure develops dipolar vorticity and electrostatic potential fields, resulting in rapid radial acceleration and formation of a steep front and a trailing wake. While the dynamical evolution strongly depends on the amount of collisional diffusion and viscosity, the structure travels a radial distance many times its initial size in all parameter regimes in the absence of sheath dissipation. In the ideal limit, there is an inertial scaling for the maximum radial velocity of isolated filaments. This velocity scales as the acoustic speed times the square root of the structure size relative to the length scale of the magnetic field. The plasma filament eventually decelerates due to mixing and collisional dissipation. Finally, the role of sheath dissipation is investigated. When included in the simulations, it significantly reduces the radial velocity of isolated filaments. The results are discussed in the context of convective transport in scrape-off layer plasmas, comprising both blob-like structures in low confinement modes and edge localized mode filaments in unstable high confinement regimes.

Garcia, O. E.; Bian, N. H.; Fundamenski, W. [Association EURATOM-Risoe National Laboratory, P.O. Box 49, OPL-128 Risoe, DK-4000 Roskilde (Denmark); School of Physics and Astronomy, University of Manchester, Manchester M60 1QD (United Kingdom); EURATOM/UKAEA Fusion Association, Culham Science Centre, Abingdon OX14 3DB (United Kingdom)

2006-08-15

293

Drebrin-induced Stabilization of Actin Filaments*  

PubMed Central

Drebrin is a mammalian neuronal protein that binds to and organizes filamentous actin (F-actin) in dendritic spines, the receptive regions of most excitatory synapses that play a crucial role in higher brain functions. Here, the structural effects of drebrin on F-actin were examined in solution. Depolymerization and differential scanning calorimetry assays show that F-actin is stabilized by the binding of drebrin. Drebrin inhibits depolymerization mainly at the barbed end of F-actin. Full-length drebrin and its C-terminal truncated constructs were used to clarify the domain requirements for these effects. The actin binding domain of drebrin decreases the intrastrand disulfide cross-linking of Cys-41 (in the DNase I binding loop) to Cys-374 (C-terminal) but increases the interstrand disulfide cross-linking of Cys-265 (hydrophobic loop) to Cys-374 in the yeast mutants Q41C and S265C, respectively. We also demonstrate, using solution biochemistry methods and EM, the rescue of filament formation by drebrin in different cases of longitudinal interprotomer contact perturbation: the T203C/C374S yeast actin mutant and grimelysin-cleaved skeletal actin (between Gly-42 and Val-43). Additionally, we show that drebrin rescues the polymerization of V266G/L267G, a hydrophobic loop yeast actin mutant with an impaired lateral interface formation between the two filament strands. Overall, our data suggest that drebrin stabilizes actin filaments through its effect on their interstrand and intrastrand contacts. PMID:23696644

Mikati, Mouna A.; Grintsevich, Elena E.; Reisler, Emil

2013-01-01

294

Multiple breathers on a vortex filament  

NASA Astrophysics Data System (ADS)

In this paper we investigate the correspondence between the Da Rios-Betchov equation, which appears in the three-dimensional motion of a vortex filament, and the nonlinear Schrödinger equation. Using this correspondence we map a set of solutions corresponding to breathers in the nonlinear Schrödinger equation to waves propagating along a vortex filament. The work presented generalizes the recently derived family of vortex configurations associated with these breather solutions to a wider class of configurations that are associated with combination homoclinic/heteroclinic orbits of the 1D self-focussing nonlinear Schrödinger equation. We show that by considering these solutions of the governing nonlinear Schrödinger equation, highly nontrivial vortex filament configurations can be obtained that are associated with a pair of breather excitations. These configurations can lead to loop-like excitations emerging from an otherwise weakly perturbed helical vortex. The results presented further demonstrate the rich class of solutions that are supported by the Da Rios-Betchov equation that is recovered within the local induction approximation for the motion of a vortex filament.

Salman, H.

2014-10-01

295

Giant molecular filaments in the Milky Way  

NASA Astrophysics Data System (ADS)

Throughout the Milky Way, molecular clouds typically appear filamentary, and mounting evidence indicates that this morphology plays an important role in star formation. What is not known is to what extent the dense filaments most closely associated with star formation are connected to the surrounding diffuse clouds up to arbitrarily large scales. How are these cradles of star formation linked to the Milky Way's spiral structure? Using archival Galactic plane survey data, we have used multiple datasets in search of large-scale, velocity-coherent filaments in the Galactic plane. In this paper, we present our methods employed to identify coherent filamentary structures first in extinction and confirmed using Galactic Ring Survey data. We present a sample of seven giant molecular filaments (GMFs) that have lengths on the order of ~100 pc, total masses of 104-105 M?, and exhibit velocity coherence over their full length. The GMFs we study appear to be inter-arm clouds and may be the Milky Way analogs to spurs observed in nearby spiral galaxies. We find that between 2 and 12% of the total mass (above ~1020 cm-2) is "dense" (above 1022 cm-2), where filaments near spiral arms in the Galactic midplane tend to have higher dense gas mass fractions than those further from the arms. Appendix A is available in electronic form at http://www.aanda.org

Ragan, S. E.; Henning, Th.; Tackenberg, J.; Beuther, H.; Johnston, K. G.; Kainulainen, J.; Linz, H.

2014-08-01

296

Filamentation instability in a quantum magnetized plasma  

Microsoft Academic Search

The filamentation instability occurring when a nonrelativistic electron beam passes through a quantum magnetized plasma is investigated by means of a cold quantum magnetohydrodynamic model. It is proved that the instability can be completely suppressed by quantum effects if and only if a finite magnetic field is present. A dimensionless parameter is identified that measures the strength of quantum effects.

A. Bret

2008-01-01

297

Filamentation instability in a quantum plasma  

Microsoft Academic Search

The growth rate of the filamentation instability triggered when a diluted cold electron beam passes through a cold plasma is evaluated using the quantum hydrodynamic equations. Compared with a cold fluid model, quantum effects reduce both the unstable wave vector domain and the maximum growth rate. Stabilization of large wave vector modes is always achieved, but significant reduction of the

A. Bret

2007-01-01

298

Blade technology program for large wind turbines, phase 1  

NASA Astrophysics Data System (ADS)

A research program for the development and construction of rotor blades is presented. The project includes investigation and design of blade concepts, compilation of materials properties of fiber reinforced plastics, and manufacturing and testing of critical blade sections. The following parts are produced and tested to check the manufacturing technology: element for load introduction, shell section in sandwich-spar technology, filament-wound D-spar in carbon fiber reinforced epoxy, and filament-wound D-spar with rear profile box in tube-winding technology. It is shown that the carbon and glass fiber reinforced plastics blade with wound D-spar is optimum. This blade has the lowest mass that can be economically manufactured by automatic filament winding.

Muser, D.

1984-10-01

299

Exact solution for the extensional flow of a viscoelastic filament  

Microsoft Academic Search

We solve the free boundary problem for the dynamics of a cylindrical, axisymmetric vis- coelastic filament stretching in a gravity-driven extensional flow for the Upper Convected Maxwell and Oldroyd-B constitutive models. Assuming the axial stress in the filament has a spatial dependence provides the simplest coupling of viscoelastic effects to the motion of the filament, and yields a closed system

LINDA B. S MOLKA; ANDREW BELMONTE; DIANE M. H ENDERSON; THOMAS P. WITELSKI

2004-01-01

300

Unusual paired helical filaments in progressive supranuclear palsy  

Microsoft Academic Search

Unusual paired helical filaments (PHF) coexisting with single filaments were observed in neurofibrillary degeneration (NFD) in the globus pallidus, subthalamic nucleus, substantia nigra, and pontine tegmentum of a typical case of progressive supranuclear palsy (PSP). Each filament had a diameter of 10–12 nm and showed central low density and a smooth contour. The thickest portion of a pair was 22–24

S. Takauchi; T. Mizuhara; K. Miyoshi

1983-01-01

301

Solar Filament Material Oscillations and Drainage before Eruption  

NASA Astrophysics Data System (ADS)

Both large-amplitude longitudinal (LAL) oscillations and material drainage in a solar filament are associated with the flow of material along the filament axis, often followed by an eruption. However, the relationship between these two motions and a subsequent eruption event is poorly understood. We analyze a filament eruption using EUV imaging data captured by the Atmospheric Imaging Array on board the Solar Dynamics Observatory and the H? images from the Global Oscillation Network Group. Hours before the eruption, the filament was activated, with one of its legs undergoing a slow rising motion. The asymmetric activation inclined the filament relative to the solar surface. After the active phase, LAL oscillations were observed in the inclined filament. The oscillation period increased slightly over time, which may suggest that the magnetic fields supporting the filament evolve to be flatter during the slow rising phase. After the oscillations, a significant amount of filament material was drained toward one filament endpoint, followed immediately by the violent eruption of the filament. The material drainage may further support the change in magnetic topology prior to the eruption. Moreover, we suggest that the filament material drainage could play a role in the transition from a slow to a fast rise of the erupting filament.

Bi, Yi; Jiang, Yunchun; Yang, Jiayan; Hong, Junchao; Li, Haidong; Yang, Dan; Yang, Bo

2014-08-01

302

Calibration and Temperature Profile of a Tungsten Filament Lamp  

ERIC Educational Resources Information Center

The goal of this work proposed for undergraduate students and teachers is the calibration of a tungsten filament lamp from electric measurements that are both simple and precise, allowing to determine the temperature of tungsten filament as a function of the current intensity. This calibration procedure was first applied to a conventional filament

de Izarra, Charles; Gitton, Jean-Michel

2010-01-01

303

Smoke Sheets and Vortex Filaments with Flexible Reconnection  

E-print Network

). Fluid motion is simulated using vortex filaments (center) and the smoke surface is tracked usingSmoke Sheets and Vortex Filaments with Flexible Reconnection Alfred Barnat CMU-CS-11-123 July 2011, Smoke, Vorticity, Vortex Filaments #12;Abstract Smoke is one of the core phenomena which fluid

304

Shape analysis of filamentous Precambrian microfossils and modern cyanobacteria  

E-print Network

Shape analysis of filamentous Precambrian microfossils and modern cyanobacteria David Boal and Ray strains of modern filamentous cyanobacteria, all with diameters of a few microns. Among 1.9­2-Ga than the filament diameters, these values lie in the same range as the cyanobacteria Geitlerinema

Boal, David

305

The effective resistance between twisted superconducting filaments in tapes  

Microsoft Academic Search

We consider two mechanisms, which influence the effective resistance between crossing strands on flat cables or filaments in twisted tapes. The one-layer classical Rutherford-type cable and the tapes with twisted BSCCO filaments in silver matrix are taken as analogous cases. The amount of the matrix between strands or filaments increases the effective conductance compared with the direct current paths (determined

S. Takács; M. Iwakuma; K. Funaki

2001-01-01

306

Capillary torque in a liquid bridge between two angled filaments  

NASA Astrophysics Data System (ADS)

Capillary torque is induced when a liquid bridge forms between two angle-positioned filaments. This paper aims to study the dependency of such capillary torque upon the filament orientation angle, filament spacing, contact angle, and liquid volume through detailed numerical simulation using a surface finite element scheme. Numerical results show that for hydrophilic liquid with contact angle below 90° and at given liquid volume as well as filament spacing, the surface energy of the system grows nonlinearly with increasing filament orientation angle from 0° (parallel filaments) to 90° (cross-positioned filaments). Accordingly, the capillary torque induced by the distorted liquid bridge increases from a torque-free state at 0° to the peak value and then decreases to the second torque-free state at 90°. At fixed filament orientation angle, the capillary torque grows with the liquid volume while decreases rapidly with increasing either contact angle or filament spacing. The peak value of capillary torque depends upon both the geometries and wetting property of the liquid bridge-filament system. A family of characteristic curves in terms of capillary torque with the filament orientation angle is determined at varying volume of liquid bridge, filament spacing ratio, and contact angle. The results and concepts developed in work are applicable for the study of wetting and spreading of liquids in fiber networks, microfluidics-based microstructural assembly, biological cell operation, etc.

Bedarkar, Amol; Wu, Xiang-Fa

2009-12-01

307

Periodic Motion Along Solar Filaments , Jeongwoo Lee1  

E-print Network

Periodic Motion Along Solar Filaments Ju Jing1,2 , Jeongwoo Lee1 , Thomas J. Spirock1,2 , Haimin restoring force and damping mechanism. Subject headings: Sun: corona -- Sun: filaments -- Sun: prominences --Sun: oscillations 1. Introduction Oscillatory mass motions in and around filaments (prominences

308

A penny-shaped crack in a filament-reinforced matrix. I - The filament model. II - The crack problem  

NASA Technical Reports Server (NTRS)

The study deals with the elastostatic problem of a penny-shaped crack in an elastic matrix which is reinforced by filaments or fibers perpendicular to the plane of the crack. An elastic filament model is first developed, followed by consideration of the application of the model to the penny-shaped crack problem in which the filaments of finite length are asymmetrically distributed around the crack. Since the primary interest is in the application of the results to studies relating to the fracture of fiber or filament-reinforced composites and reinforced concrete, the main emphasis of the study is on the evaluation of the stress intensity factor along the periphery of the crack, the stresses in the filaments or fibers, and the interface shear between the matrix and the filaments or fibers. Using the filament model developed, the elastostatic interaction problem between a penny-shaped crack and a slender inclusion or filament in an elastic matrix is formulated.

Erdogan, F.; Pacella, A. H.

1974-01-01

309

Wind turbine generator rotor blade concepts with low cost potential  

NASA Technical Reports Server (NTRS)

Four processed for producing blades are examined. Two use filament winding techniques and two involve filling a mold or form to produce all or part of a blade. The processes are described and a comparison is made of cost, material properties, design and free vibration characteristics. Conclusions are made regarding the feasibility of each process to produce low cost, structurally adequate blades.

Sullivan, T. L.; Cahill, T. P.; Griffee, D. G., Jr.; Gewehr, H. W.

1977-01-01

310

DC Machine  

NSDL National Science Digital Library

The effect of the commutator is to produce a fixed spatial distribution of current directions in the armature conductors (shown as blue & green circles) independent of shaft rotation. The field created by these currents (armature reaction) is vertically directed along the quadrature axis. The field established by the excitation of the stator poles is directed along the horizontal direct axis. This package presents computer models of electric machines based on the space vector formulation leading to the assessment of the dynamic performance of open- and closed-loopac and dc drive systems. The Simulink/Matlab implementation is adopted because of its inherent integration of vectorized system representations in block diagram form, of numerical analysis methods, of graphical portrayal of time evolutions of signals combined with the simple realization of the functionality of controllers and power electronic excitations. The development of Simulink models of drive assemblies is a relatively simple task consisting of combining input-output block representation of the various components making up the system; these blocks can readily be reused (utilizing standard copy-and-paste techniques) to modify the system components or the configuration of the system. This approach provides a powerful design tool because of the ease of observing the effects of parameters modifications and of differing system configurations and control strategies.

Riaz, Mahmoud

2012-08-29

311

Galactic Winds in the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

We have performed hydrodynamical simulations to investigate the effects of galactic winds on the high-redshift (z=3) universe. Strong winds suppress the formation of low-mass galaxies significantly, and the metals carried by them produce C IV absorption lines with properties in reasonable agreement with observations. The winds have little effect on the statistics of the H I absorption lines, because the hot gas bubbles blown by the winds fill only a small fraction of the volume and because they tend to escape into the voids, thereby leaving the filaments that produce these lines intact. Based on observations made at the W. M. Keck Observatory, which is operated as a scientific partnership between the California Institute of Technology and the University of California; it was made possible by the generous support of the W. M. Keck Foundation.

Theuns, Tom; Viel, Matteo; Kay, Scott; Schaye, Joop; Carswell, Robert F.; Tzanavaris, Panayiotis

2002-10-01

312

A new wind energy conversion system  

NASA Technical Reports Server (NTRS)

It is presupposed that vertical axis wind energy machines will be superior to horizontal axis machines on a power output/cost basis and the design of a new wind energy machine is presented. The design employs conical cones with sharp lips and smooth surfaces to promote maximum drag and minimize skin friction. The cones are mounted on a vertical axis in such a way as to assist torque development. Storing wind energy as compressed air is thought to be optimal and reasons are: (1) the efficiency of compression is fairly high compared to the conversion of mechanical energy to electrical energy in storage batteries; (2) the release of stored energy through an air motor has high efficiency; and (3) design, construction, and maintenance of an all-mechanical system is usually simpler than for a mechanical to electrical conversion system.

Smetana, F. O.

1975-01-01

313

The structures, mass motions and footpoints of solar filaments  

NASA Astrophysics Data System (ADS)

This thesis focuses on identifying the mechanism by which solar filaments acquire mass. Some of the speculations for how a filament gets its mass are 1) injection of mass from the chromosphere into the filament structure, and 2) condensation of mass from the corona into the region of the filament channel. Mass motion at the footpoints of the filaments is studied to detect mass entering and leaving the filament body. The magnetic properties of the footpoints of the filaments are also studied. Recommendations are drawn by comparing observational properties obtained in this study with the features used in some of the previously developed models. The datasets used for this study are high-resolution image sets of centerline and Doppler wings of Halpha, obtained using the Dutch Open Telescope (DOT). The data were obtained on Oct 30, 2010. The data set contains three filaments in an active region in the northern hemisphere of the Sun. The images in each wavelength are aligned and made into movies to find the footpoints of the filaments through which the mass goes into and comes out of the filaments from and to the chromosphere, respectively. The magnetic properties of the footpoints are studied by overlaying the magnetogram images with the DOT images by using full-disk Halpha images for matching the features in the two. Of the three filaments, one of the filaments is observed to be stable throughout the duration of the observations; another filament erupts after about two hours of the beginning of observations; and the third filament is in its early stages of formation. The ends of the stable filament are clearly observed whereas the ends of the erupting filament and the forming filament are observed clearly intermittently during the duration of the observations. The animations of the region near the ends of filament 1 reveal definite injection and draining of mass via the footpoints into and out of the filament. The mass motion into and out of the filaments are observed to be comparable with that occurring in chromospheric fibrils. Of the total number of footpoints observed, a majority of them appear to be rooted on or on the borders of the majority polarities of the active region.

Venkataramanasastry, Aparna

314

51. FIRST FLOOR INTERIOR VIEW TO SOUTHEAST: Winding machinery to ...  

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

51. FIRST FLOOR INTERIOR VIEW TO SOUTHEAST: Winding machinery to right, and belt-driven machine tools to left. Museum mezzanine in upper portion of photo. - San Francisco Cable Railway, Washington & Mason Streets, San Francisco, San Francisco County, CA

315

Superconducting generators for large off shore wind turbines   

E-print Network

This thesis describes four novel superconducting machine concepts, in the pursuit of finding a suitable design for large offshore wind turbines. The designs should be reliable, modular and light-weight. The main novelty ...

Keysan, Ozan

2014-06-30

316

Transition from linear- to nonlinear-focusing regime in filamentation  

PubMed Central

Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser filaments and, consequently, a transition between a collimated and a strongly focused filament is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition, and show that it corresponds to an actual shift in the balance of physical mechanisms governing filamentation. In high-NA conditions, filamentation is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters, and our analysis agrees well with a wide range of parameters found in published literature. PMID:25434678

Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin

2014-01-01

317

Transition from linear- to nonlinear-focusing regime in filamentation  

NASA Astrophysics Data System (ADS)

Laser filamentation in gases is often carried out in the laboratory with focusing optics to better stabilize the filament, whereas real-world applications of filaments frequently involve collimated or near-collimated beams. It is well documented that geometrical focusing can alter the properties of laser filaments and, consequently, a transition between a collimated and a strongly focused filament is expected. Nevertheless, this transition point has not been identified. Here, we propose an analytical method to determine the transition, and show that it corresponds to an actual shift in the balance of physical mechanisms governing filamentation. In high-NA conditions, filamentation is primarily governed by geometrical focusing and plasma effects, while the Kerr nonlinearity plays a more significant role as NA decreases. We find the transition between the two regimes to be relatively insensitive to the intrinsic laser parameters, and our analysis agrees well with a wide range of parameters found in published literature.

Lim, Khan; Durand, Magali; Baudelet, Matthieu; Richardson, Martin

2014-12-01

318

Wind Generator  

NSDL National Science Digital Library

Windmills have been used for hundreds of years to collect energy from the wind in order to pump water, grind grain, and more recently generate electricity. There are many possible designs for the blades of a wind generator and engineers are always trying new ones. Design and test your own wind generator, then try to improve it by running a small electric motor connected to a voltage sensor.

Consortium, The C.

2012-05-21

319

Origin and Evolution of Filament-Prominence Systems  

NASA Astrophysics Data System (ADS)

We present a ``head-to-tail'' linkage model for the formation, evolution, and eruption of solar filaments. The magnetic field structure of our model is based on the observation that filaments form exclusively in filament channels with no apparent magnetic connections above the polarity inversion line. The formation of a filament in this configuration is driven by flux convergence and cancellation, which produces looplike filament segments with a half-turn. Filament segments of like chirality may connect and form long quiescent filaments. Such filaments are stabilized through footpoint anchoring until further cancellation at the footpoints causes their eruption. The eruption restores the original filament channel so that filament formation may resume immediately. We then demonstrate that the combined workings of Hale's polarity law, Joy's law, and differential rotation introduce a strong hemispheric preference in the chirality of filaments formed poleward of the sunspot belt, which is in agreement with observations. We analyze the magnetic fine structure of filaments formed through our model and find consistency with the observed hemispheric preference for barb orientation and a simple explanation for barb formation. Finally, we consider the flux tubes retracted below the surface in the process of filament formation. We show that every cancellation event that generates a filament obeying the hemispheric chirality preference injects a flux tube below the surface with a poloidal field opposite that of the ongoing cycle. We suggest that this pattern of submergence of flux represents the specific mechanism for the reversal of the poloidal flux in a Babcock-Leighton-Durney-type model for the solar dynamo.

Martens, Petrus C.; Zwaan, Cornelis

2001-09-01

320

Can Machines BeCan Machines Be Polite?Polite?  

E-print Network

Can Machines BeCan Machines Be Polite?Polite? Michael A. CovingtonMichael A. Covington Artificial Intelligence CenterArtificial Intelligence Center #12;Can machines be polite?Can machines be polite? Machines have beenMachines have been annoying peopleannoying people ever since humanever since human--machine

Covington, Michael A.

321

Synthesis of high performance PM motors with concentrated windings  

Microsoft Academic Search

The windings concentrated around the teeth offer obvious advantages for the electrical machines with radial air-gap, because the volume of copper used in the end-windings can be reduced. The Joule losses are decreased, and the efficiency is improved. These machines are still limited to applications of sub-fractional power and they generally present a reduced number of phases. In the three-phase

Jéröme Cros; Philippe Viarouge

2002-01-01

322

DOE large horizontal axis wind turbine development at NASA Lewis Research Center  

NASA Technical Reports Server (NTRS)

Large wind turbine activities managed by NASA Lewis are reviewed. These activities include results from the first and second generation field machines (Mod-OA, -1, and -2), the status of the Department of Interior WTS-4 machine for which NASA is responsible for technical management, and the design phase of the third generation wind turbines (Mod-5).

Linscott, B. S.

1982-01-01

323

Influence of multiple ionization in laser filamentation  

NASA Astrophysics Data System (ADS)

Laser filaments in gases result from the nonlinear balance between optical Kerr self-focusing and plasma generation in the single ionization limit, i.e., the pulse intensity is supposed to remain moderate enough (? {{10}14} W cm?2) to apply photo-ionization theories valid for an averaged ion charge less than unity. However, no theory has attempted so far to consider how an ionization model allowing a priori multiple-charged states could impact the standard filamentation scenario. Here, we discuss a multiple photo-ionization scheme that relies on probabilities assuming successive single-electron ionizations. We numerically show that a multiple ionization scheme can increase the clamping intensity, the peak electron density and supercontinuum generation in gases with high binding energy, e.g., helium.

González de Alaiza Martínez, P.; Bergé, L.

2014-10-01

324

Online Catalog for Filament-Sigmoid Correlation  

NASA Astrophysics Data System (ADS)

A new online catalog correlating H-alpha filaments with SXT sigmoids gives researchers, teachers and pre-college students the ability to access digital H-alpha images online that were previously available only at the physical location of the NSO at Sunspot, NM. This web-based catalog correlates SOHO's SXT sigmoids from 1993-1998 as described in a non-online catalog created by Zach Blehm under the direction of Richard Canfield, MSU-Bozeman, with H-alpha filament activity as described by Ivy Merriot under the direction of Alexei Pevtsov, NSO, and Petrus Martens, MSU-Bozeman. The H-alpha images were digitized from film archives of the Flare Patrol Telescope at Sunspot, NM. Use of the online catalog will be demonstrated at the poster site with critical comments encouraged.

Merriot, Ivy; Pevtsov, A.; Martens, P.

2007-05-01

325

Solar Magnetized "Tornadoes": Relation to Filaments  

E-print Network

Solar magnetized "tornadoes", a phenomenon discovered in the solar atmosphere, appear as tornado-like structures in the corona but root in the photosphere. Like other solar phenomena, solar tornadoes are a feature of magnetized plasma and therefore differ distinctly from terrestrial tornadoes. Here we report the first analysis of solar "tornadoes" {Two papers which focused on different aspect of solar tornadoes were published in the Astrophysical Journal Letters (Li et al. 2012) and Nature (Wedemeyer-B\\"ohm et al. 2012), respectively, during the revision of this Letter.}. A detailed case study of two events indicates that they are rotating vertical magnetic structures probably driven by underlying vortex flows in the photosphere. They usually exist as a group and relate to filaments/prominences, another important solar phenomenon whose formation and eruption are still mysteries. Solar tornadoes may play a distinct role in the supply of mass and twists to filaments. These findings could lead to a new explanati...

Su, Yang; Veronig, Astrid; Temmer, Manuela; Gan, Weiqun

2012-01-01

326

Morphogenesis of filaments growing in flexible confinements  

NASA Astrophysics Data System (ADS)

Space-saving design is a requirement that is encountered in biological systems and the development of modern technological devices alike. Many living organisms dynamically pack their polymer chains, filaments or membranes inside deformable vesicles or soft tissue-like cell walls, chorions and buds. Surprisingly little is known about morphogenesis due to growth in flexible confinements—perhaps owing to the daunting complexity lying in the nonlinear feedback between packed material and expandable cavity. Here we show by experiments and simulations how geometric and material properties lead to a plethora of morphologies when elastic filaments are growing far beyond the equilibrium size of a flexible thin sheet they are confined in. Depending on friction, sheet flexibility and thickness, we identify four distinct morphological phases emerging from bifurcation and present the corresponding phase diagram. Four order parameters quantifying the transitions between these phases are proposed.

Vetter, R.; Wittel, F. K.; Herrmann, H. J.

2014-07-01

327

Morphogenesis of filaments growing in flexible confinements  

E-print Network

Space-saving design is a requirement that is encountered in biological systems and the development of modern technological devices alike. Many living organisms dynamically pack their polymer chains, filaments or membranes inside of deformable vesicles or soft tissue like cell walls, chorions, and buds. Surprisingly little is known about morphogenesis due to growth in flexible confinements - perhaps owing to the daunting complexity lying in the nonlinear feedback between packed material and expandable cavity. Here we show by experiments and simulations how geometric and material properties lead to a plethora of morphologies when elastic filaments are growing far beyond the equilibrium size of a flexible thin sheet they are confined in. Depending on friction, sheet flexibility and thickness, we identify four distinct morphological phases emerging from bifurcation and present the corresponding phase diagram. Four order parameters quantifying the transitions between these phases are proposed.

Roman Vetter; Falk K. Wittel; Hans J. Herrmann

2014-07-17

328

Stator for Rotating Electrical Machine Having Multiple Controlwindings  

SciTech Connect

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 biasfield.

Shah, Manoj R.; Lewandowski, Chad R.

1999-05-05

329

Acceleration and vortex filaments in turbulence  

E-print Network

We report recent results from a high resolution numerical study of fluid particles transported by a fully developed turbulent flow. Single particle trajectories were followed for a time range spanning more than three decades, from less than a tenth of the Kolmogorov time-scale up to one large-eddy turnover time. We present some results concerning acceleration statistics and the statistics of trapping by vortex filaments.

F. Toschi; L. Biferale; G. Boffetta; A. Celani; B. J. Devenish; A. Lanotte

2005-01-23

330

Molecular Phylogeny of Metazoan Intermediate Filament Proteins  

Microsoft Academic Search

.   We have cloned cytoplasmic intermediate filament (IF) proteins from a large number of invertebrate phyla using cDNA probes,\\u000a the monoclonal antibody IFA, peptide sequence information, and various RT-PCR procedures. Novel IF protein sequences reported\\u000a here include the urochordata and nine protostomic phyla, i.e., Annelida, Brachiopoda, Chaetognatha, Echiura, Nematomorpha,\\u000a Nemertea, Platyhelminthes, Phoronida, and Sipuncula. Taken together with the wealth of

Andreas Erber; Dieter Riemer; Marc Bovenschulte; Klaus Weber

1998-01-01

331

Impact damage in filament wound composite bottles  

NASA Technical Reports Server (NTRS)

Increasingly, composite materials are being used in advanced structural applications because of the significant weight savings they offer when compared to more traditional engineering materials. The higher cost of composites must be offset by the increased performance that results from reduced structural weight if these new materials are to be used effectively. At present, there is considerable interest in fabricating solid rocket motor cases out of composite materials, and capitalizing on the reduced structural weight to increase rocket performance. However, one of the difficulties that arises when composite materials are used is that composites can develop significant amounts of internal damage during low velocity impacts. Such low velocity impacts may be encountered in routine handling of a structural component like a rocket motor case. The ability to assess the reduction in structural integrity of composite motor cases that experience accidental impacts is essential if composite rocket motor cases are to be certified for manned flight. While experimental studies of the post-impact performance of filament wound composite motor cases haven been proven performed (2,3), scaling impact data from small specimens to full scale structures has proven difficult. If such a scaling methodology is to be achieved, an increased understanding of the damage processes which influence residual strength is required. The study described herein was part of an ongoing investigation of damage development and reduction of tensile strength in filament wound composites subjected to low velocity impacts. The present study, which focused on documenting the damage that develops in filament wound composites as a result of such impacts, included two distinct tasks. The first task was to experimentally assess impact damage in small, filament wound pressure bottles using x-ray radiography. The second task was to study the feasibility of using digital image processing techniques to assist in determining the 3-D distribution of damage from stereo x-ray pairs.

Highsmith, Alton L.

1993-01-01

332

Dynamics of the neuronal intermediate filaments  

PubMed Central

We have analyzed the dynamics of neuronal intermediate filaments in living neurons by using the method of photobleaching of fluorescently- labeled neurofilament L protein and immunoelectron microscopy of incorporation sites of biotinylated neurofilament L protein. Low-light- level imaging and photobleaching of growing axons of mouse sensory neurons did not affect the rate of either axonal growth or the addition of intermediate filament structures at the axon terminal, suggesting that any perturbations caused by these optical methods would be minimal. After laser photobleaching, recovery of fluorescence did occur slowly with a recovery half-time of 40 min. Furthermore, we observed a more rapid fluorescence recovery in growing axons than in quiescent ones, indicating a growth-dependent regulation of the turnover rate. Incorporation sites of biotin-labeled neurofilament L protein were localized as numerous discrete sites along the axon, and they slowly elongated to become continuous arrays 24 h after injection. Collectively, these results indicate that neuronal intermediate filaments in growing axons turn over within the small area of the axoplasm possibly by the mechanism of lateral and segmental incorporation of new subunits. PMID:8468352

1993-01-01

333

A first approach to filament dynamics  

NASA Astrophysics Data System (ADS)

Modelling elastic filament dynamics is a topic of high interest due to the wide range of applications. However, it has reached a high level of complexity in the literature, making it unaccessible to a beginner. In this paper we explain the main steps involved in the computational modelling of the dynamics of an elastic filament. We first derive equations governing the dynamics of an elastic lament suitable for a computer simulation implementation. The derivation starts from the relation between forces and potential energy in conservative systems in order to derive the equation of motion of any bead in the filament. Only two-dimensional movements are considered, but extensions to three dimensions can follow similar lines. Suggestions for computer implementations are provided in Matlab as well as an example of application related to the generation of musical sounds. This example allows a critical analysis of the numerical results obtained using a cross-disciplinary perspective. Since derivations start from basic physics equations, use simple calculus and computational implementations are straightforward, this paper proposes a different approach to introduce simple molecular dynamics simulations or animations of real systems in undergraduate elasticity or computer modelling courses.

Silva, P. E. S.; Vistulo de Abreu, F.; Simões, R.; Dias, R. G.

2010-11-01

334

Force Generation by Actin Filament Growth*  

NASA Astrophysics Data System (ADS)

Nearly all types of living cells are capable of crawling motion in the presence of chemical attractants. The force driving this motion is believed to result from the growth of polymeric actin filaments which push against the cell membrane. The maximum force available from such filament growth is given by simple thermodynamic considerations, but the rate of growth is not well understood. The talk will present simulations of the growth of actin fibers against mobile obstacles based on Langevin dynamics, with actin monomers treated as the ``atoms" of the simulation. The actin-actin interactions are treated by a simple angular force field which stabilizes the one-dimensional filament structure. The force-velocity curves obtained by these simulations decay more rapidly with force than is predicted by existing analytic theories [C. S. Peskin, G. M. Odell, and G. F. Oster, Biophys. J. 65, 316-324 (1993)]. These discrepancies are explained via the inhibition of diffusion near the fiber tip by the impinging membrane *Supported by NIH Grant GM38542-12.

Carlsson, A. E.

2000-03-01

335

Reconnection of vortex filaments and Kolmogorov spectrum  

E-print Network

The energy spectrum of the 3D velocity field, induced by collapsing vortex filaments is studied. One of the aims of this work is to clarify the appearance of the Kolmogorov type energy spectrum $E(k)\\varpropto k^{-5/3}$, observed in many numerical works on discrete vortex tubes (quantized vortex filaments in quantum fluids). Usually, explaining classical turbulent properties of quantum turbulence, the model of vortex bundles, is used. This model is necessary to mimic the vortex stretching, which is responsible for the energy transfer in classical turbulence. In our consideration we do not appeal to the possible "bundle arrangement" but explore alternative idea that the turbulent spectra appear from singular solution, which describe the collapsing line at moments of reconnection. One more aim is related to an important and intensively discussed topic - a role of hydrodynamic collapse in the formation of turbulent spectra. We demonstrated that the specific vortex filament configuration generated the spectrum $E(k)$ close to the Kolmogorov dependence and discussed the reason for this as well as the reason for deviation. We also discuss the obtained results from point of view of the both classical and quantum turbulence.

Sergey K. Nemirovskii

2014-04-19

336

Elasticity of a filamentous kagome lattice  

NASA Astrophysics Data System (ADS)

The diluted kagome lattice, in which bonds are randomly removed with probability 1-p, consists of straight lines that intersect at points with a maximum coordination number of 4. If lines are treated as semiflexible polymers and crossing points are treated as cross-links, this lattice provides a simple model for two-dimensional filamentous networks. Lattice-based effective-medium theories and numerical simulations for filaments modeled as elastic rods, with stretching modulus ? and bending modulus ?, are used to study the elasticity of this lattice as functions of p and ?. At p=1, elastic response is purely affine, and the macroscopic elastic modulus G is independent of ?. When ?=0, the lattice undergoes a first-order rigidity-percolation transition at p=1. When ?>0, G decreases continuously as p decreases below one, reaching zero at a continuous rigidity-percolation transition at p=pb?0.605 that is the same for all nonzero values of ?. The effective-medium theories predict scaling forms for G, which exhibit crossover from bending-dominated response at small ?/? to stretching-dominated response at large ?/? near both p=1 and pb, that match simulations with no adjustable parameters near p=1. The affine response as p?1 is identified with the approach to a state with sample-crossing straight filaments treated as elastic rods.

Mao, Xiaoming; Stenull, Olaf; Lubensky, T. C.

2013-04-01

337

Hot filament CVD of boron nitride films  

DOEpatents

Using a hot filament (.apprxeq.1400.degree. C.) to activate borazine (B.sub.3 N.sub.3 H.sub.6) molecules for subsequent reaction with a direct line-of-sight substrate, transparent boron ntiride films as thick as 25,000 angstroms are grown for a substrate temperature as low as 100.degree. C. The minimum temperature is determined by radiative heating from the adjacent hot filament. The low temperature BN films show no indication of crystallinity with X-ray diffraction (XRD). X-ray photoelectron spectra (XPS) show the films to have a B:N ratio of 0.97:1 with no other XPS detectable impurities above the 0.5% level. Both Raman and infrared (IR) spectroscopy are characteristic of h-BN with small amounts of hydrogen detected as N-H and B-H bands in the IR spectrum. An important feature of this method is the separation and localization of the thermal activation step at the hot filament from the surface reaction and film growth steps at the substrate surface. This allows both higher temperature thermal activation and lower temperature film growth.

Rye, Robert R. (Albuquerque, NM)

1992-01-01

338

Hybrid Quantum Cloning Machine  

E-print Network

In this work, we introduce a special kind of quantum cloning machine called Hybrid quantum cloning machine. The introduced Hybrid quantum cloning machine or transformation is nothing but a combination of pre-existing quantum cloning transformations. In this sense it creates its own identity in the field of quantum cloners. Hybrid quantum cloning machine can be of two types: (i) State dependent and (ii) State independent or Universal. We study here the above two types of Hybrid quantum cloning machines. Later we will show that the state dependent hybrid quantum-cloning machine can be applied on only four input states. We will also find in this paper another asymmetric universal quantum cloning machine constructed from the combination of optimal universal B-H quantum cloning machine and universal anti-cloning machine. The fidelities of the two outputs are different and their values lie in the neighborhood of ${5/6} $

Satyabrata Adhikari; A. K. Pati; Indranil Chakrabarty; B. S. Choudhury

2007-06-14

339

Superconducting generators for wind turbines: Design considerations  

NASA Astrophysics Data System (ADS)

The harmonic content of high temperature superconductors (HTS) field winding in air-core high temperature superconducting synchronous machine (HTS SM) has been addressed in order to investigate tendency of HTS SM towards mechanical oscillation and additional loss caused by higher flux harmonic. Both analytical expressions for flux distribution and current sheet distribution have been derived and analyzed. The two main contributors to the AC loss of HTS rotor winding are also identified and their influence addressed on general level.

Mijatovic, N.; Abrahamsen, A. B.; Træholt, C.; Seiler, E.; Henriksen, M.; Rodriguez-Zermeno, V. M.; Pedersen, N. F.

2010-06-01

340

Meteorology (Wind)  

Atmospheric Science Data Center

... is in each range (0-2, 3-6, 7-10, 11-14, 15-18, 19-25 m/s).   Wind Speed at 50 m at 3-hourly intervals (m/s)   ... be adjusted to heights from 10 to 300 meters using the Gipe power law. Wind speeds may be adjusted for different terrain by selecting from ...

2014-09-25

341

Wind energy  

Microsoft Academic Search

General resources of wind energy are evaluated, and its main applications are considered, such as conversion into electricity and heat, hydrogen production, and irrigation, along with the associated problem of long-term energy storage. The basic principles of windmill system design and favorable location selection are outlined. The environmental impact of the windmill systems is discussed. It is noted that wind

B. Sorensen

1976-01-01

342

Impact damage detection in filament wound tubes utilizing embedded optical fibers  

NASA Astrophysics Data System (ADS)

Filament wound tubes are currently being used extensively in service because of their superior specific properties and the relatively simple manufacturing technique involved in their properties. However, the reinforcing fibers can suffer from low velocity impact damage (approximately 10 ms-1) during service. Such damage can result in poor post- impact properties which in certain applications can reduce the burst strength below safe working levels. This paper discusses the use of optical fiber sensors, embedded during the filament winding process, to provide information on specified levels of impact damage incurred by the tube during service. The sensors being developed use silica based optical fibers in composites made from E-glass reinforcing fibers and high temperature cure epoxy resins. Various methods of damage detection are being evaluated to select the optimum sensor arrangement. These systems detect changes in the transmission characteristics of the optical fiber. The objective being to produce a working damage detection system which provides sensitive, cheap, accurate and reliable information about the levels of impact damage sustained by the tube. This paper presents initial results from the impact damage detection systems being evaluated for use in filament wound tubes. Issues relating to chemical compatibility between optical fiber sensors and the epoxy resin system were also investigated as part of this study. These results aid selection of the correct optical fiber properties to achieve reliable and sensitive systems. The advantages of using a new profile sensor compared to an optical fiber are also discussed.

Martin, Anthony R.; Hayes, Simon A.; Fernando, Gerard F.; Hale, Ken F.

1995-04-01

343

Microwave processing of ceramic oxide filaments. Annual report, FY1997  

SciTech Connect

The objective of the microwave filament processing project is to develop microwave techniques to manufacture continuous ceramic oxide filaments. Microwave processing uses the volumetric absorption of microwave power in oxide filament tows to drive off process solvents, to burn out organic binders, and to sinter the dried fibers to produce flexible, high-strength ceramic filaments. The technical goal is to advance filament processing technology by microwave heating more rapidly with less energy and at a lower cost than conventional processing, but with the same quality as conventional processing. The manufacturing goal is to collaborate with the 3M Company, a US manufacturer of ceramic oxide filaments, to evaluate the technology using a prototype filament system and to transfer the microwave technology to the 3M Company. Continuous ceramic filaments are a principal component in many advanced high temperature materials like continuous fiber ceramic composites (CFCC) and woven ceramic textiles. The use of continuous ceramic filaments in CFCC radiant burners, gas turbines, waste incineration, and hot gas filters in U.S. industry and power generation is estimated to save at least 2.16 quad/yr by year 2010 with energy cost savings of at least $8.1 billion. By year 2010, continuous ceramic filaments and CFCC`s have the potential to abate pollution emissions by 917,000 tons annually of nitrous oxide and 118 million tons annually of carbon dioxide (DOE Report OR-2002, February, 1994).

Vogt, G.J.

1998-12-31

344

Geometry of flexible filament cohesion: better contact through twist?  

PubMed

Cohesive interactions between filamentous molecules have broad implications for a range of biological and synthetic materials. While long-standing theoretical approaches have addressed the problem of inter-filament forces from the limit of infinitely rigid rods, the ability of flexible filaments to deform intra-filament shape in response to changes in inter-filament geometry has a profound affect on the nature of cohesive interactions. In this paper, we study two theoretical models of inter-filament cohesion in the opposite limit, in which filaments are sufficiently flexible to maintain cohesive contact along their contours, and address, in particular, the role played by helical-interfilament geometry in defining interactions. Specifically, we study models of featureless, tubular filaments interacting via: (1) pair-wise Lennard-Jones (LJ) interactions between surface elements and (2) depletion-induced filament binding stabilized by electrostatic surface repulsion. Analysis of these models reveals a universal preference for cohesive filament interactions for non-zero helical skew, and further, that in the asymptotic limit of vanishing interaction range relative to filament diameter, the skew-dependence of cohesion approaches a geometrically defined limit described purely by the close-packing geometry of twisted tubular filaments. We further analyze non-universal features of the skew-dependence of cohesion at small-twist for both potentials, and argue that in the LJ model the pair-wise surface attraction generically destabilizes parallel filaments, while in the second model, pair-wise electrostatic repulsion in combination with non-pairwise additivity of depletion leads to a meta-stable parallel state. PMID:25381544

Cajamarca, Luis; Grason, Gregory M

2014-11-01

345

Geometry of flexible filament cohesion: Better contact through twist?  

NASA Astrophysics Data System (ADS)

Cohesive interactions between filamentous molecules have broad implications for a range of biological and synthetic materials. While long-standing theoretical approaches have addressed the problem of inter-filament forces from the limit of infinitely rigid rods, the ability of flexible filaments to deform intra-filament shape in response to changes in inter-filament geometry has a profound affect on the nature of cohesive interactions. In this paper, we study two theoretical models of inter-filament cohesion in the opposite limit, in which filaments are sufficiently flexible to maintain cohesive contact along their contours, and address, in particular, the role played by helical-interfilament geometry in defining interactions. Specifically, we study models of featureless, tubular filaments interacting via: (1) pair-wise Lennard-Jones (LJ) interactions between surface elements and (2) depletion-induced filament binding stabilized by electrostatic surface repulsion. Analysis of these models reveals a universal preference for cohesive filament interactions for non-zero helical skew, and further, that in the asymptotic limit of vanishing interaction range relative to filament diameter, the skew-dependence of cohesion approaches a geometrically defined limit described purely by the close-packing geometry of twisted tubular filaments. We further analyze non-universal features of the skew-dependence of cohesion at small-twist for both potentials, and argue that in the LJ model the pair-wise surface attraction generically destabilizes parallel filaments, while in the second model, pair-wise electrostatic repulsion in combination with non-pairwise additivity of depletion leads to a meta-stable parallel state.

Cajamarca, Luis; Grason, Gregory M.

2014-11-01

346

Extreme Kicking Machine  

NSDL National Science Digital Library

In this design challenge activity follow up to "Kicking Machine", learners add a hands-free feature to their Kicking Machine. Learners modify their kicking machine to have it either release the pendulum or rubber band while standing three feet away or have it automatically feed balls into the kicking machine, one after another. They must figure out how to integrate the new feature into the existing structure and use the design process to make sure the modified kicking machine works properly. Educators can use this activity to demonstrate simple machines and kinetic/potential energy.

2012-08-20

347

Low cost composite materials for wind energy conversion systems  

NASA Technical Reports Server (NTRS)

A winding process utilizing a low-cost E-glass fabric called transverse-filament tape for low-cost production of wind turbine generators (WTG) is described. The process can be carried out continuously at high speed to produce large one-piece parts with tapered wall thicknesses on a tapered mandrel. It is being used to manufacture blades for the NASA/DOE 200-ft-diameter MOD-1 WTG and Rockwell/DOE 40-kW small wind energy conversion system (SWECS).

Weingart, O.

1980-01-01

348

15 CFR 700.31 - Metalworking machines.  

Code of Federal Regulations, 2013 CFR

...section include: Bending and forming machines Boring machines Broaching machines Drilling and tapping machines Electrical discharge, ultrasonic and chemical erosion machines Forging machinery and hammers Gear cutting and...

2013-01-01

349

Finite-element analysis and design of a radial-field brushless PM machine utilizing soft magnetic composites  

Microsoft Academic Search

Soft magnetic composites (SMC) are emerging in electrical machine design offering the potential for innovative machine geometries and lower cost manufacturing. This paper examines the design and analysis of a SMC-based radial-field fractional-slot concentrated-winding permanent magnet machine using 2D finite-element analysis. Its performance is compared with an existing conventionally-laminated, distributed-winding baseline design for two cases, firstly with the same active

G. S. Liew; C. Tang; W. L. Soong; N. Ertugrul; D. B. Gehlert

2011-01-01

350

REAL-TIME ROTOR BAR CURRENT MEASUREMENTS USING BLUETOOTH TECHNOLOGY FOR A BRUSHLESS DOUBLY-FED MACHINE (BDFM)  

E-print Network

mover speed is variable, such as in wind turbines. For variable speed operation one of the machine. Details of the theory and operation of the machine are given in [1,2] and references therein. Although-FED MACHINE (BDFM) P. C. Roberts, E. Abdi Jalebi, R. A. McMahon and T. J. Flack Engineering Department

Cambridge, University of

351

Dynamics of solar filaments. IV - Structure and mass flow of an active region filament  

NASA Technical Reports Server (NTRS)

An active region filament near the center of the solar disk was observed on September 29-30, 1980, with the Multichannel Subtractive Double Pass Spectrograph of the Meudon solar tower and the UV Spectrograph and Polarimeter aboard the SMM satellite. H-alpha and C IV measurements are presently used to study brightness and material velocity in the 10,000 and 100,000 K temperature ranges, and photospheric magnetograms are used to investigate the underlying magnetic field. Attention is given to the constraints imposed on possible filament structures by observations, as well as the expected MHD relationships.

Schmieder, B.; Malherbe, J. M.; Simon, G.; Poland, A. I.

1985-01-01

352

Assembly of type IV neuronal intermediate filaments in nonneuronal cells in the absence of preexisting cytoplasmic intermediate filaments  

PubMed Central

We report here on the in vivo assembly of alpha-internexin, a type IV neuronal intermediate filament protein, in transfected cultured cells, comparing its assembly properties with those of the neurofilament triplet proteins (NF-L, NF-M, and NF-H). Like the neurofilament triplet proteins, alpha-internexin coassembles with vimentin into filaments. To study the assembly characteristics of these proteins in the absence of a preexisting filament network, transient transfection experiments were performed with a non-neuronal cell line lacking cytoplasmic intermediate filaments. The results showed that only alpha-internexin was able to self-assemble into extensive filamentous networks. In contrast, the neurofilament triplet proteins were incapable of homopolymeric assembly into filamentous arrays in vivo. NF-L coassembled with either NF-M or NF-H into filamentous structures in the transfected cells, but NF-M could not form filaments with NF-H. alpha- internexin could coassemble with each of the neurofilament triplet proteins in the transfected cells to form filaments. When all but 2 and 10 amino acid residues were removed from the tail domains of NF-L and NF-M, respectively, the resulting NF-L and NF-M deletion mutants retained the ability to coassemble with alpha-internexin into filamentous networks. These mutants were also capable of forming filaments with other wild-type neurofilament triplet protein subunits. These results suggest that the tail domains of NF-L and NF-M are dispensable for normal coassembly of each of these proteins with other type IV intermediate filament proteins to form filaments. PMID:8376465

1993-01-01

353

20% Wind Energy 20% Wind Energy  

E-print Network

(government, industry, utilities, NGOs) Analyzes wind's potential contributions to energy security, economic · Transmission a challenge #12;Wind Power Class Resource Potential Wind Power Density at 50 m W/m 2 Wind Speed20% Wind Energy by 2030 20% Wind Energy by 2030 #12;Presentation and Objectives Overview Background

Powell, Warren B.

354

A filament supported by different magnetic field configurations  

NASA Astrophysics Data System (ADS)

A nonlinear force-free magnetic field extrapolation of vector magnetogram data obtained by THEMIS/MTR on 2005 May 27 suggests the simultaneous existence of different magnetic configurations within one active region filament: one part of the filament is supported by field line dips within a flux rope, while the other part is located in dips within an arcade structure. Although the axial field chirality (dextral) and the magnetic helicity (negative) are the same along the whole filament, the chiralities of the filament barbs at different sections are opposite, i.e., right-bearing in the flux rope part and left-bearing in the arcade part. This argues against past suggestions that different barb chiralities imply different signs of helicity of the underlying magnetic field. This new finding about the chirality of filaments will be useful to associate eruptive filaments and magnetic cloud using the helicity parameter in the Space Weather Science.

Guo, Y.; Schmieder, B.; Démoulin, P.; Wiegelmann, T.; Aulanier, G.; Török, T.; Bommier, V.

2011-08-01

355

[Characteristics of filamentous fungal biofilms and their roles in ophthalmology].  

PubMed

A filamentous fungal biofilm is a collection of hyphae and spores encased in a matrix, which has distinct developmental phases governed by complex molecular events. Resistance to antifungal drugs and components of the innate immune system remain the greatest threats to patients with filamentous fungal biofilms. There is increasing evidence that filamentous fungal biofilms play a role in a variety of ocular infections. Filamentous fungal biofilms may participate in ocular infections by allowing filamentous fungi to persist on abiotic surfaces that come in contact with the eye, and by direct biofilm formation on biotic surfaces of the eye. This review discusses the current understanding of the basic biology and clinical implications associated with filamentous fungal biofilms in ophthalmology. PMID:25533563

Zhang, Xiaoyan; Sun, Xuguang

2014-09-01

356

Dynamics and mechanics of motor-filament systems  

NASA Astrophysics Data System (ADS)

Motivated by the cytoskeleton of eukaryotic cells, we develop a general framework for describing the large-scale dynamics of an active filament network. In the cytoskeleton, active cross-links are formed by motor proteins that are able to induce relative motion between filaments. Starting from pair-wise interactions of filaments via such active processes, our framework is based on momentum conservation and an analysis of the momentum flux. This allows us to calculate the stresses in the filament network generated by the action of motor proteins. We derive effective theories for the filament dynamics which can be related to continuum theories of active polar gels. As an example, we discuss the stability of homogenous isotropic filament distributions in two spatial dimensions.

Kruse, K.; Jülicher, F.

2006-08-01

357

A FILAMENT ERUPTION ON 2010 OCTOBER 21 FROM THREE VIEWPOINTS  

SciTech Connect

A filament eruption on 2010 October 21 observed from three different viewpoints by the Solar Terrestrial Relations Observatory and the Solar Dynamic Observatory is analyzed by also invoking data from the Solar and Heliospheric Observatory and the Kanzelhoehe Solar Observatory. The position of the filament just before the eruption at the central meridian not far from the center of the solar disk was favorable for photospheric magnetic field measurements in the area below the filament. Because of this, we were able to calculate with high precision the distribution of the coronal potential magnetic field near the filament. We found that the filament began to erupt when it approached the height in the corona where the magnetic field decay index was greater than 1. We also determined that during the initial stage of the eruption the filament moved along the magnetic neutral surface.

Filippov, Boris, E-mail: bfilip@izmiran.ru [Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation of the Russian Academy of Sciences (IZMIRAN), Troitsk, Moscow 142190 (Russian Federation)

2013-08-10

358

Effect of initial shape on contraction dynamics of Newtonian filaments  

NASA Astrophysics Data System (ADS)

Slender liquid filaments arise in a number of applications involving drop formation, atomization, and cloud physics. Under the action of surface tension, a filament either contracts into a single drop or breaks into multiple drops as it recoils. Our understanding of the contraction of Newtonian filaments in a passive ambient fluid has improved greatly over the past two decades thanks to the numerical analyses of Schulkes (1996) and Notz and Basaran (2004) who modeled the filaments as cylinders that are terminated by two identical hemispherical caps. However, in many situations, the initial shape of a filament may resemble more that of two unequal globular or spherical drops that are connected by a slender cylinder. The dynamics of contraction of such filaments are studied here by both a two-dimensional analysis and a one-dimensional slender-jet analysis, and the results are summarized by constructing phase diagrams involving the dimensionless groups governing the dynamics.

Sambath, Krishnaraj; McGough, Patrick; Appathurai, Santosh; Bhat, Pradeep; Harris, Michael; Basaran, Osman

2009-11-01

359

Microwave guiding in air along single femtosecond laser filament  

SciTech Connect

Microwave guiding along single plasma filament generated through the propagation of femtosecond (fs) laser pulses in air has been demonstrated over a distance of about 6.5 cm, corresponding to a microwave signal intensity enhancement of more than 3-fold over free space propagation. The current propagation distance along the fs laser filament is in agreement with the calculations and limited by the relatively high resistance of the single plasma filament. Using a single fs laser filament to channel microwave radiation considerably alleviate requirements to the power of fs laser pulses compared to the case of the circular filaments waveguide. In addition, it can be used as a simple and non-intrusive method to obtain the basic parameters of laser-generated plasma filament.

Ren Yu; Alshershby, Mostafa; Qin Jiang; Hao Zuoqiang; Lin Jingquan [School of Science, Changchun University of Science and Technology, Changchun 130022 (China)

2013-03-07

360

Wind Energy Leasing Handbook  

E-print Network

Wind Energy Leasing Handbook Wind Energy Leasing Handbook E-1033 Oklahoma Cooperative Extension?..................................................................................................................... 31 What do wind developers consider in locating wind energy projects?............................................................................................ 37 How do companies and individuals invest in wind energy projects?....................................................................

Balasundaram, Balabhaskar "Baski"

361

Interactive Gumball Machine  

NSDL National Science Digital Library

In this activity, learners review the history of gumball machines and explore potential and kinetic energy, while working in teams to build a gumball slide. Teams then design and build their own interactive gumball machine.

2013-08-30

362

Infinite Time Turing Machines  

Microsoft Academic Search

Infinite time Turing machines extend the operation of ordinary Turing machines into transfinite ordinal time. By doing so, they provide a natural model of infinitary computability, a theoretical setting for the analysis of the power and limitations of supertask algorithms.

Joel David Hamkins

2002-01-01

363

LISP Machine Progress Report  

E-print Network

This informal paper introduces the LISP Machine, describes the goals and current status of the project, and explicates some of the key ideas. It covers the LISP machine implementation, LISP as a system language, ...

Bawden, Alan

1977-08-01

364

Stirling machine operating experience  

NASA Technical Reports Server (NTRS)

Numerous Stirling machines have been built and operated, but the operating experience of these machines is not well known. It is important to examine this operating experience in detail, because it largely substantiates the claim that Stirling machines are capable of reliable and lengthy lives. The amount of data that exists is impressive, considering that many of the machines that have been built are developmental machines intended to show proof of concept, and were not expected to operate for any lengthy period of time. Some Stirling machines (typically free-piston machines) achieve long life through non-contact bearings, while other Stirling machines (typically kinematic) have achieved long operating lives through regular seal and bearing replacements. In addition to engine and system testing, life testing of critical components is also considered.

Ross, Brad; Dudenhoefer, James E.

1991-01-01

365

Stirling machine operating experience  

NASA Astrophysics Data System (ADS)

Numerous Stirling machines have been built and operated, but the operating experience of these machines is not well known. It is important to examine this operating experience in detail, because it largely substantiates the claim that Stirling machines are capable of reliable and lengthy lives. The amount of data that exists is impressive, considering that many of the machines that have been built are developmental machines intended to show proof of concept, and were not expected to operate for any lengthy period of time. Some Stirling machines (typically free-piston machines) achieve long life through non-contact bearings, while other Stirling machines (typically kinematic) have achieved long operating lives through regular seal and bearing replacements. In addition to engine and system testing, life testing of critical components is also considered.

Ross, Brad A.; Dudenhoefer, James E.

366

Modeling of wind farms in the load flow analysis  

Microsoft Academic Search

Two methods are proposed, for the simulation of wind farms with asynchronous generators in the load flow analysis. Both methods are based on the steady-state model of the induction machine. The first involves improving the conventional PQ bus, and the second involves modeling the generators in steady-state in the bus where the wind farm is located. The two sets of

A. E. Feijoo; J. Cidras

2000-01-01

367

Wind Energy Conversion Systems. A Unit of Instruction.  

ERIC Educational Resources Information Center

The number of secondary schools, colleges, and universities offering courses in wind energy machine construction, repair, and installation, continues to increase. It is the purpose of this unit to include the study of wind energy conversion systems (WECS) as an integral part of related vocational and technical curriculum materials. The unit's…

Greenwald, Martin

368

Stellar Winds  

NASA Astrophysics Data System (ADS)

A "stellar wind" is the continuous, supersonic outflow of matter from the surface layers of a star. Our sun has a solar wind, driven by the gas-pressure expansion of the hot (T > 106 K) solar corona. It can be studied through direct in situ measurement by interplanetary spacecraft; but analogous coronal winds in more distant solar-type stars are so tenuous and transparent that that they are difficult to detect directly. Many more luminous stars have winds that are dense enough to be opaque at certain wavelengths of the star's radiation, making it possible to study their wind outflows remotely through careful interpretation of the observed stellar spectra. Red giant stars show slow, dense winds that may be driven by the pressure from magnetohydrodyanmic waves. As stars with initial mass up to 8 M ? evolve toward the Asymptotic Giant Branch (AGB), a combination of stellar pulsations and radiative scattering off dust can culminate in "superwinds" that strip away the entire stellar envelope, leaving behind a hot white dwarf stellar core with less than the Chandrasekhar mass of ˜ ?? 1. 4M ?. The winds of hot, luminous, massive stars are driven by line-scattering of stellar radiation, but such massive stars can also exhibit superwind episodes, either as Red Supergiants or Luminous Blue Variable stars. The combined wind and superwind mass loss can strip the star's hydrogen envelope, leaving behind a Wolf-Rayet star composed of the products of earlier nuclear burning via the CNO cycle. In addition to such direct effects on a star's own evolution, stellar winds can be a substantial source of mass, momentum, and energy to the interstellar medium, blowing open large cavities or "bubbles" in this ISM, seeding it with nuclear processed material, and even helping trigger the formation of new stars, and influencing their eventual fate as white dwarves or core-collapse supernovae. This chapter reviews the properties of such stellar winds, with an emphasis on the various dynamical driving processes and what they imply for key wind parameters like the wind flow speed and mass loss rate.

Owocki, Stan

369

Global Winds  

NSDL National Science Digital Library

On this worksheet, students examine a diagram of global winds and learn the position of the prevailing westerlies, the polar easterlies, the trade winds, the horse latitudes and the doldrums, and that together, the uneven heating of the planet by the Sun and the Coriolis Effect are responsible for the global wind belts. The resource is part of the teacher's guide accompanying the video, NASA Why Files: The Case of the Mysterious Red Light. Lesson objectives supported by the video, additional resources, teaching tips and an answer sheet are included in the teacher's guide.

2012-08-03

370

Wind Tunnel  

NSDL National Science Digital Library

Scientists use enormous wind tunnels to test the design of planes, helicopters, even the Space Shuttle. In this simulation activity, learners create a miniature wind tunnel test by blowing air with a fan or blow dryer through a large tube, then flying paper airplanes, helicopters and other folded paper models in the "wind." Unless the source of the air is a fan that stands on its own, for example, more than one person will be needed to do the activity.This activity can be combined with the Helicopter Twirl, Parachute Drop and Boomerang activities, also found on the Lawrence Hall of Science Kids Site.

Science, Lawrence H.

2009-01-01

371

Quadraphonic Wind  

NSDL National Science Digital Library

In this activity, learners discover how the extent of various wind speeds changes in each of the four quadrants around a hurricane. Learners use data from the 'present' location of Hurricane Bill (2009) to plot the distance of various wind speeds that extend from the center of the storm. This resource includes brief background information about hurricanes and forecasting as well as an explanation of the Hurricane Bill data used in this activity and how small increases in wind speed can cause increased potential for damage.

Service, National W.

2012-12-18

372

Tailoring femtosecond laser pulse filamentation using plasma photonic lattices  

SciTech Connect

We demonstrate experimentally that by using transient plasma photonic lattices, the attributes of intense femtosecond laser filaments, such as peak intensity and length, can be dynamically controlled. The extended plasma lattice structure is generated using two co-propagating non-diffracting intense Bessel beams in water. The use of such transient lattice structures to control the competition between linear and nonlinear effects involved in filamentation opens the way for extensive control of the filamentation process.

Suntsov, Sergiy; Abdollahpour, Daryoush; Panagiotopoulos, Paris [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, P.O. Box 1527, 71110 Heraklion (Greece); Papazoglou, Dimitrios G.; Tzortzakis, Stelios [Institute of Electronic Structure and Laser, Foundation for Research and Technology Hellas, P.O. Box 1527, 71110 Heraklion (Greece); Materials Science and Technology Department, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Couairon, Arnaud [Centre de Physique Theorique, CNRS, Ecole Polytechnique, F-91128 Palaiseau (France)

2013-07-08

373

Developments in hot-filament metal oxide deposition (HFMOD)  

Microsoft Academic Search

Hot-filament metal oxide deposition (HFMOD) is a variant of conventional hot-filament chemical vapor deposition (HFCVD) recently developed in our laboratory and successfully used to obtain high-quality, uniform films of MOx, WOx and VOx. The method employs the controlled oxidation of a filament of a transition metal heated to 1000 °C or more in a rarefied oxygen atmosphere (typically, of about 1 Pa).

Steven F. Durrant; Benedito C. Trasferetti; Jair Scarmínio; Celso U. Davanzo; Francisco P. M. Rouxinol; Rogério V. Gelamo; Mario A. Bica de Moraes

2008-01-01

374

A Conceptual Model of the Formation of Filament Barbs  

NASA Astrophysics Data System (ADS)

Barbs are the structures along the sides of a filament that connect its horizontal axis to chromosphere. The barbs, previously called 'legs' can be considered as magnetic field conduits along which mass is continuously guided and transported to and from the chromosphere. In the model presented, the barbs represent a secondary stage in filament formation which follows an intial stage in which a nearly horizontal axial magnetic field is first formed along a filament channel. Barb formation is most effectively and readily illustrated where the filament channel is broad and well-developed such as exists among the decaying network remnants of active regions. In these circumstances, the filament channel is a region of relatively low magnetic flux density compared to adjacent areas further from the polarity inversion. H-alpha filtergrams show that the axial parts of the filament are low and nearly contiguous with the chromosphere. The low height of the axial field, and the relative absence of concentrations of network magnetic field, are favorable conditions for magnetic reconnection between the axial field of the filament and new ephemeral regions and intranetwork magnetic fields beneath the filament. These reconnections lead to the formation of the barbs joining parts of the newly emerged fields to the axial field of the filament. Barb formation and motions seen in H-alpha filtergrams provide the evidence for this initial part of the conceptual model. The remaining part of the model is a demonstration of why only right-bearing barbs are seen on dextral filaments and left-bearing barbs on sinistral filaments; this is due to the sinistral or dextral magnetic configuration of the filament channel which does not permit the survival of barbs of the non-observed chirality as will be illustrated.

Martin, S. F.

1997-05-01

375

Low cost flux-switching brushless AC machines  

Microsoft Academic Search

A low cost 3-phase DC winding excited flux-switching (FS) brushless AC machine is developed from the FS permanent magnet (FSPM) machine. The influence of stator and rotor pole number combination on its electromagnetic performance, including flux-linkage and back-emf waveforms, electromagnetic static torque, and torque-current density characteristics, are predicted by 2-D finite element analyses and validated by experiment. In addition, the

J. T. Chen; Z. Q. Zhu; S. Iwasaki; R. Deodhar

2010-01-01

376

The Advantage of Machines  

NSDL National Science Digital Library

In this lesson, students learn about work as defined by physical science and see that work is made easier through the use of simple machines. Already encountering simple machines everyday, students will be learn about their widespread uses in improving everyday life. This lesson serves as the starting point for the Simple Machines Unit.

Integrated Teaching And Learning Program

377

Talking Vending Machines  

E-print Network

're in the central Tokyo Station and you're thirsty so you go to the, you know, vending machine to buy a drink. Only this is not your average vending machine. Uh uh. This vending machine has opinions on what beverage you want. Sensors built into large touch panels...

Hacker, Randi

2011-02-02

378

Cable-Twisting Machine  

NASA Technical Reports Server (NTRS)

New cable-twisting machine is smaller and faster than many production units. Is useful mainly in production of short-run special cables. Already-twisted cable can be fed along axis of machine. Faster operation than typical industrial cable-twisting machines possible by using smaller spools of wire.

Kurnett, S.

1982-01-01

379

Automatic Inspection During Machining  

NASA Technical Reports Server (NTRS)

In experimental manufacturing process, numerically-controlled machine tool temporarily converts into inspection machine by installing electronic touch probes and specially-developed numerical-control software. Software drives probes in paths to and on newly machined parts and collects data on dimensions of parts.

Ransom, Clyde L.

1988-01-01

380

Find the Simple Machines  

NSDL National Science Digital Library

This is a web activity about simple machines. Learners will explore a lawn mower and identify six different simple machines which work together to help make our lives easier. This is an excellent activity for exploring how simple machines, and science in general, apply to learners' everyday lives.

Cosi

2000-01-01

381

Your Sewing Machine.  

ERIC Educational Resources Information Center

The programed instruction manual is designed to aid the student in learning the parts, uses, and operation of the sewing machine. Drawings of sewing machine parts are presented, and space is provided for the student's written responses. Following an introductory section identifying sewing machine parts, the manual deals with each part and its…

Peacock, Marion E.

382

What is Machine Learning? About the Course Example Machine Learning  

E-print Network

What is Machine Learning? About the Course Example Machine Learning DD2431 ¨Orjan Ekeberg Oct­Dec, 2007 What is Machine Learning? About the Course Example 1 What is Machine Learning? Definition A Hypothetical Project What is Machine Learning? About the Course Example 1 What is Machine Learning? Definition

Kjellström, Hedvig

383

What is Machine Learning? About the Course Example Machine Learning  

E-print Network

What is Machine Learning? About the Course Example Machine Learning DD2431 ¨Orjan Ekeberg Oct­Dec, 2007 #12;What is Machine Learning? About the Course Example 1 What is Machine Learning? Definition A Hypothetical Project #12;What is Machine Learning? About the Course Example 1 What is Machine Learning

Kjellström, Hedvig

384

What is Machine Learning? About the Course Example Machine Learning  

E-print Network

What is Machine Learning? About the Course Example Machine Learning DD2431 ¨Orjan Ekeberg Oct­Dec, 2008 #12;What is Machine Learning? About the Course Example 1 What is Machine Learning? Definition A Hypothetical Project #12;What is Machine Learning? About the Course Example 1 What is Machine Learning

Kjellström, Hedvig

385

What is Machine Learning? About the Course Example Machine Learning  

E-print Network

What is Machine Learning? About the Course Example Machine Learning DD2431 ¨Orjan Ekeberg Oct­Dec, 2008 What is Machine Learning? About the Course Example 1 What is Machine Learning? Definition A Hypothetical Project What is Machine Learning? About the Course Example 1 What is Machine Learning? Definition

Kjellström, Hedvig

386

Why Machine Learning and Games? Machine Learning in Video Games  

E-print Network

#12;Why Machine Learning and Games? Machine Learning in Video Games DrivatarsTM Reinforcement entertainment valueWhat is the best AI? #12;Why Machine Learning and Games? Machine Learning in Video Games;#12;Why Machine Learning and Games? Machine Learning in Video Games DrivatarsTM Reinforcement Learning

Hunt, Galen

387

Circular tests for HSM machine tools: Bore machining application  

E-print Network

operations lies in understanding the impact of machine tool behaviour on machining time and part qualityCircular tests for HSM machine tools: Bore machining application Abstract: Today's High-Speed Machining (HSM) machine tool combines productivity and part quality. The difficulty inherent in HSM

Paris-Sud XI, Université de

388

Mechanism of Actin Filament Bundling by Fascin  

SciTech Connect

Fascin is the main actin filament bundling protein in filopodia. Because of the important role filopodia play in cell migration, fascin is emerging as a major target for cancer drug discovery. However, an understanding of the mechanism of bundle formation by fascin is critically lacking. Fascin consists of four {beta}-trefoil domains. Here, we show that fascin contains two major actin-binding sites, coinciding with regions of high sequence conservation in {beta}-trefoil domains 1 and 3. The site in {beta}-trefoil-1 is located near the binding site of the fascin inhibitor macroketone and comprises residue Ser-39, whose phosphorylation by protein kinase C down-regulates actin bundling and formation of filopodia. The site in {beta}-trefoil-3 is related by pseudo-2-fold symmetry to that in {beta}-trefoil-1. The two sites are {approx}5 nm apart, resulting in a distance between actin filaments in the bundle of {approx}8.1 nm. Residue mutations in both sites disrupt bundle formation in vitro as assessed by co-sedimentation with actin and electron microscopy and severely impair formation of filopodia in cells as determined by rescue experiments in fascin-depleted cells. Mutations of other areas of the fascin surface also affect actin bundling and formation of filopodia albeit to a lesser extent, suggesting that, in addition to the two major actin-binding sites, fascin makes secondary contacts with other filaments in the bundle. In a high resolution crystal structure of fascin, molecules of glycerol and polyethylene glycol are bound in pockets located within the two major actin-binding sites. These molecules could guide the rational design of new anticancer fascin inhibitors.

Jansen, Silvia; Collins, Agnieszka; Yang, Changsong; Rebowski, Grzegorz; Svitkina, Tatyana; Dominguez, Roberto (UPENN); (UPENN-MED)

2013-03-07

389

Primary Masters in Machine Learning  

E-print Network

Primary Masters in Machine Learning Student Handbook #12;#12;Page 1 Masters in Machine Learning:.......................................................................................8 Machine Learning Journal Club ..................................................................12 #12;Page 3 Introduction The field of machine learning is concerned with the question of how

390

Improving the electrochemical performance of carbon filaments by solvent cleansing  

SciTech Connect

Found inherent in the submicron-diameter vapor-grown carbon filament fabrication process was a tarry residue, which comprised polyaromatic hydrocarbons. Cyclic voltammetry conducted using carbon working electrodes and an iron cyanide electrolyte showed that the residue harmed the electrochemical performance. Removal of the residue from the filaments using a solvent resulted in increases in the electron transfer rate (to values as high as 0.2 cm/s) and reversibility of the iron cyanide redox species, increase in the packing density and decrease in the filament-filament contact electrical resistivity.

Shui, X.; Chung, D.D.L. [State Univ. of New York, Buffalo, NY (United States). Composite Materials Research Lab.; Frysz, C.A. [Wilson Greatbatch, Ltd., Clarence, NY (United States)

1995-12-31

391

Structural Polymorphism in Tau Filaments: An Implication for Neurodegenerative Diseases.  

E-print Network

??Tau filaments are the pathological hallmark of >20 neurodegenerative diseases including Alzheimer's disease, Pick's disease, and progressive supranuclear palsy. In the adult human brain, six… (more)

Siddiqua, Ayisha

392

Direct Characterization of Femtosecond Laser Filaments in Air  

NASA Astrophysics Data System (ADS)

Some of the excitement about the utility of high power femtosecond lasers originated largely from the observation that such lasers can create extremely intense laser filaments that can be self-guided as they propagate in the atmosphere. These filaments are generated as a consequence of the nonlinear self-focusing of the air and plasma formation by multiphoton ionization at the intense power levels available in the femtosecond lasers. The intensity inside such a filament can easily reach 10^13 W/cm^2 and above. Such intensities are sufficient to cause breakdown on almost all solid surfaces. Thus, a non-destructive diagnosis of these filaments have always been a problem since most conventional detection methods can quickly end with a collection of burnt optics. Characteristics of the filaments have traditionally been inferred from indirect measurement techniques. We will discuss a new diagnostic technique that allows direct observation of the filaments. Measurements of the filament size along with the fluence in the interior of the filaments will be presented. Measurements of white light and harmonic generation in the filaments will also be presented.

Ting, A.; Gordon, D.; Alexeev, I.; Briscoe, E.; Penano, J.; Sprangle, P.

2003-10-01

393

History and phylogeny of intermediate filaments: now in insects.  

PubMed

Intermediate filaments include the nuclear lamins, which are universal in metazoans, and the cytoplasmic intermediate filaments, which are much more varied and form cell type-specific networks in animal cells. Until now, it has been thought that insects harbor lamins only. This view is fundamentally challenged by the discovery, reported in BMC Biology, of an intermediate filament-like cytoplasmic protein, isomin, in the hexapod Isotomurus maculatus. Here we briefly review the history of research on intermediate filaments, and discuss the implications of this latest finding in the context of what is known of their structure and functions. PMID:21356127

Herrmann, Harald; Strelkov, Sergei V

2011-01-01

394

Evolution of cytomotive filaments: the cytoskeleton from prokaryotes to eukaryotes.  

PubMed

The basic features of the active filaments that use nucleotide hydrolysis to organise the cytoplasm are remarkably similar in the majority of all cells and are either actin-like or tubulin-like. Nearly all prokaryotic cells contain at least one form of FtsZ, the prokaryotic homologue of tubulin and some bacterial plasmids use tubulin-like TubZ for segregation. The other main family of active filaments, assembled from actin-like proteins, occurs in a wide range of bacterial species as well as in all eukaryotes. Some bacterial plasmids also use ParM, another actin-like protein. Higher-order filament structures vary from simple to complex depending on the cellular application. Equally, filament-associated proteins vary greatly between species and it is not possible currently to trace their evolution from prokaryotes to eukaryotes. This lack of similarity except in the three-dimensional structures and longitudinal interactions between the filament subunits hints that the most basic cellular function of the filaments is to act as linear motors driven by assembly dynamics and/or bending and hence we term these filament systems 'cytomotive'. The principle of cytomotive filaments seems to have been invented independently for actin- and tubulin-like proteins. Prokaryotes appear to have a third class of cytomotive filaments, typically associated with surfaces such as membranes or DNA: Walker A cytoskeletal ATPases (WACA). A possible evolutionary relationship of WACAs with eukaryotic septins is discussed. PMID:18768164

Löwe, Jan; Amos, Linda A

2009-02-01

395

Spontaneous symmetry breaking of a hinged flapping filament generates lift.  

PubMed

Elastic filamentous structures found on swimming and flying organisms are versatile in function, rendering their precise contribution to locomotion difficult to assess. We show in this Letter that a single passive filament hinged on the rear of a bluff body placed in a stream can generate a net lift force without increasing the mean drag force on the body. This is a consequence of spontaneous symmetry breaking in the filament's flapping dynamics. The phenomenon is related to a resonance between the frequency associated with the von Kármán vortex street developing behind the bluff body and the natural frequency of the free bending vibrations of the filament. PMID:23102315

Bagheri, Shervin; Mazzino, Andrea; Bottaro, Alessandro

2012-10-12

396

Modeling Vertical Plasma Flows in Solar Filament Barbs  

NASA Astrophysics Data System (ADS)

Speeds of observed flows in quiescent solar filaments are typically much less than the local Alfvén speed. This is why the flows in filament barbs can be modeled by perturbing a local magnetostatic solution describing the balance between the Lorentz force, gravity, and gas pressure in a barb. Similarly, large-scale filament flows can be treated as adiabatically slow deformations of a force-free magnetic equilibrium that describes the global structure of a filament. This approach reconciles current theoretical models with the puzzling observational result that some of the flows appear to be neither aligned with the magnetic field nor controlled by gravity.

Litvinenko, Y.

2003-12-01

397

Hollow cylindrical plasma filament waveguide with discontinuous finite thickness cladding  

SciTech Connect

We have explored here a hollow cylindrical laser plasma multifilament waveguide with discontinuous finite thickness cladding, in which the separation between individual filaments is in the range of several millimeters and the waveguide cladding thickness is in the order of the microwave penetration depth. Such parameters give a closer representation of a realistic laser filament waveguide sustained by a long stable propagation of femtosecond (fs) laser pulses. We report how the waveguide losses depend on structural parameters like normalized plasma filament spacing, filament to filament distance or pitch, normal spatial frequency, and radius of the plasma filament. We found that for typical plasma parameters, the proposed waveguide can support guided modes of microwaves in extremely high frequency even with a cladding consisting of only one ring of plasma filaments. The loss of the microwave radiation is mainly caused by tunneling through the discontinuous finite cladding, i.e., confinement loss, and is weakly dependent on the plasma absorption. In addition, the analysis indicates that the propagation loss is fairly large compared with the loss of a plasma waveguide with a continuous infinite thickness cladding, while they are comparable when using a cladding contains more than one ring. Compared to free space propagation, this waveguide still presents a superior microwave transmission to some distance in the order of the filamentation length; thus, the laser plasma filaments waveguide may be a potential channel for transporting pulsed-modulated microwaves if ensuring a long and stable propagation of fs laser pulses.

Alshershby, Mostafa; Hao Zuoqiang; Lin Jingquan [School of Science, Changchun University of Science and Technology, Changchun 130022 (China)

2013-01-15

398

A 34-meter VAWT (Vertical Axis Wind Turbine) point design  

NASA Astrophysics Data System (ADS)

The Wind Energy Division at Sandia National Laboratories recently completed a point design based on the 34-m Vertical Axis Wind Turbine (VAWT) Test Bed. The 34-m Test Bed research machine incorporates several innovations that improve Darrieus technology, including increased energy production, over previous machines. The point design differs minimally from the Test Bed; but by removing research-related items, its estimated cost is substantially reduced. The point design is a first step towards a Test-Bed-based commercial machine that would be competitive with conventional sources of power in the mid-1990s.

Ashwill, T. D.; Berg, D. E.; Dodd, H. M.; Rumsey, M. A.; Sutherland, H. J.; Veers, P. S.

399

Wind Surge  

NSDL National Science Digital Library

This site features an interactive applet from the University of Delaware. The applet illustrates the way water can pile up against the downwind side (of a basin) due to stresses exerted on the surface by strong wind.

Robert A. Dalrymple

400

Wind Landforms  

NSDL National Science Digital Library

In this assignment, students evaluate depositional and erosional landforms created by wind processes. This exercise looks at sand dune and yardang features using satellite images and topographic maps in an online GIS.

Tranel, Lisa

401

Wind Story  

NSDL National Science Digital Library

This animation presents the characteristics of wind power as a source of clean energy. The force of moving air generates electricity, by rotating blades around a rotor. The motion of the rotor turns a driveshaft that drives an electric generator.

WPSU (Penn State University broadcast station); Domain, Teachers'

402

Folding of viscous sheets and filaments  

NASA Astrophysics Data System (ADS)

We consider the nonlinear folding behavior of a viscous filament or a sheet under the influence of an external force such as gravity. Everyday examples of this phenomenon are provided by the periodic folding of a sheet of honey as it impinges on toast, or the folding of a stream of shampoo as it falls on one's hand. To understand the evolution of a fold, we formulate and solve a free-boundary problem for the phenomenon, give scaling laws for the size of the folds and the frequency with which they are laid out, and verify these experimentally.

Skorobogatiy, M.; Mahadevan, L.

2000-12-01

403

Quantum kinetic theory of the filamentation instability  

SciTech Connect

The quantum electromagnetic dielectric tensor for a multi-species plasma is re-derived from the gauge-invariant Wigner-Maxwell system and presented under a form very similar to the classical one. The resulting expression is then applied to a quantum kinetic theory of the electromagnetic filamentation instability. Comparison is made with the quantum fluid theory including a Bohm pressure term and with the cold classical plasma result. A number of analytical expressions are derived for the cutoff wave vector, the largest growth rate, and the most unstable wave vector.

Bret, A. [ETSI Industriales, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain and Instituto de Investigaciones Energeticas y Aplicaciones Industriales, 13071 Ciudad Real (Spain); Haas, F. [Departamento de Fisica, Universidade Federal do Parana, 81531-990, Curitiba, Parana (Brazil)

2011-07-15

404

Vortex filament equation for a regular polygon  

NASA Astrophysics Data System (ADS)

In this paper, we study the evolution of the vortex filament equation, with X(s, 0) being a regular planar polygon. Using algebraic techniques, supported by full numerical simulations, we give strong evidence that X(s, t) is also a polygon at any rational time; moreover, it can be fully characterized, up to a rigid movement, by a generalized quadratic Gauß sum. We also study the fractal behaviour of X(0, t), relating it with the so-called Riemann's non-differentiable function, that was proved by Jaffard to be a multifractal.

de la Hoz, Francisco; Vega, Luis

2014-12-01

405

The bacterial cytoskeleton: more than twisted filaments  

PubMed Central

Far from being simple “bags” of enzymes, bacteria are richly endowed with ultrastructures that challenge and expand standard definitions of the cytoskeleton. Here we review rods, rings, twisted pairs, tubes, sheets, spirals, moving patches, meshes and composites, and suggest defining the term “bacterial cytoskeleton” as all cytoplasmic protein filaments and their superstructures that move or scaffold (stabilize/position/recruit) other cellular materials. The evolution of each superstructure has been driven by specific functional requirements. As a result, while homologous proteins with different functions have evolved to form surprisingly divergent superstructures, those of unrelated proteins with similar functions have converged. PMID:23183140

Pilhofer, Martin; Jensen, Grant J.

2012-01-01

406

Dynamic fluctuations of dipolar semiflexible filaments  

NASA Astrophysics Data System (ADS)

On the basis of the model of a flexible magnetic filament, the characteristics of their thermal fluctuations are considered. The crossover of the time dependence of the mean quadratic displacement from t3/4 to t1/2 at the magnetic field increase is found. Two characteristic mechanisms of the magnetization relaxation time distribution—straightening of the thermal undulations and excitation of the bending modes of the free ends under the action of an ac magnetic field—are described. In both cases, the characteristic scaling law ?-3/4 of the magnetic susceptibility in a high-frequency range is found.

Belovs, M.; C?bers, A.

2006-02-01

407

Quantum kinetic theory of the filamentation instability  

E-print Network

The quantum electromagnetic dielectric tensor for a multi species plasma is re-derived from the gauge invariant Wigner-Maxwell system and presented under a form very similar to the classical one. The resulting expression is then applied to a quantum kinetic theory of the electromagnetic filamentation instability. Comparison is made with the quantum fluid theory including a Bohm pressure term, and with the cold classical plasma result. A number of analytical expressions are derived for the cutoff wave vector, the largest growth rate and the most unstable wave vector.

A. Bret; F. Haas

2011-05-10

408

Filamentation instability in a quantum plasma  

E-print Network

The growth rate of the filamentation instability triggered when a diluted cold electron beam passes through a cold plasma is evaluated using the quantum hydrodynamic equations. Compared with a cold fluid model, quantum effects reduce both the unstable wave vector domain and the maximum growth rate. Stabilization of large wave vector modes is always achieved, but significant reduction of the maximum growth rate depends on a dimensionless parameter that is provided. Although calculations are extended to the relativistic regime, they are mostly relevant to the non-relativistic one.

A. Bret

2007-06-29

409

Biomechanical properties of intermediate filaments: from tissues to single filaments and back.  

PubMed

The animal cell cytoskeleton consists of three interconnected filament systems: actin-containing microfilaments (MFs), microtubules (MTs), and the lesser known intermediate filaments (IFs). All IF proteins share a common tripartite domain structure and the ability to assemble into 8-12 nm wide filaments. Electron microscopy data suggest that IFs are built according to a completely different plan from that of MFs and MTs. IFs are known to impart mechanical stability to cells and tissues but, until recently, the biomechanical properties of single IFs were unknown. However, with the discovery of naturally occurring micrometer-wide IF bundles and the development of new methodologies to mechanically probe single filaments, it is now possible to propose a more unified view of IF biomechanics. Unlike MFs and MTs, single IFs can now be described as flexible, extensible and tough, which has important implications for our understanding of cell and tissue mechanics. Furthermore, the molecular mechanisms at play when IFs are deformed point toward a pivotal role for them in mechanotransduction. PMID:17187357

Kreplak, Laurent; Fudge, Douglas

2007-01-01

410

Electronically commutated serial-parallel switching for motor windings  

DOEpatents

A method and a circuit for controlling an ac machine comprises controlling a full bridge network of commutation switches which are connected between a multiphase voltage source and the phase windings to switch the phase windings between a parallel connection and a series connection while providing commutation discharge paths for electrical current resulting from inductance in the phase windings. This provides extra torque for starting a vehicle from lower battery current.

Hsu, John S. (Oak Ridge, TN)

2012-03-27

411

Wind power plants in the weather conditions of Northern Finland  

NASA Astrophysics Data System (ADS)

Lappland's fells and highlands feature a notable wind power potential due to special meteorological circumstances. The wind power plants for these sites must be equipped with special means against icing and low temperatures. Icing events monitored on a small test machine are described and compared with general load assumptions. Different means of ice detection and ice removal from rotor blades are presented. Low temperature and anti-icing requirements for wind power plant components and operation control are discussed.

Bohmeke, Georg

412

National wind energy construction program: its energy and economic impact  

Microsoft Academic Search

Developing the 1.7 quad wind energy portion of the 18.5 quad (20 percent) National Renewable Energy Coal translates into 500,000 million kWh\\/year of electrical power generation. If, for example, wind dynamos that produced 10 million kWh\\/year were used, 50,000 large wind machines would be required. A Near-Term Goal of 5000 MW by 1989 is needed to develop the manufacturing industry

1980-01-01

413

Submicron nickel filaments made by electroplating carbon filaments as a new filler material for electromagnetic interference shielding  

Microsoft Academic Search

Short nickel filaments of diam 0.4 ?m and containing 94 vol% Ni and 6 vol% C were fabricated by electroplating with nickel\\u000a 0.1 ?m diam catalytically grown carbon filaments. The use of these filaments in polyether sulfone in amounts of 3, 7,13, and\\u000a 19 vol% gave composites with electromagnetic interference shielding effectiveness at 1–2 GHz of 42,87,84, and 92 dB,

Xiaoping Shui; D. D. L. Chung

1995-01-01

414

Wind power where you want it  

SciTech Connect

This article describes some of the research being done at the Alternative Energy Institute and the design and efficiency of the new wind power machines. New turbine designs are generating electricity for multiple farm uses, and the economic conditions now favor alternative power since new electric transmission installations and maintence are costly.

Comis, D.

1994-06-01

415

Superconductivity for Large Scale Wind Turbines  

SciTech Connect

A conceptual design has been completed for a 10MW superconducting direct drive wind turbine generator employing low temperature superconductors for the field winding. Key technology building blocks from the GE Wind and GE Healthcare businesses have been transferred across to the design of this concept machine. Wherever possible, conventional technology and production techniques have been used in order to support the case for commercialization of such a machine. Appendices A and B provide further details of the layout of the machine and the complete specification table for the concept design. Phase 1 of the program has allowed us to understand the trade-offs between the various sub-systems of such a generator and its integration with a wind turbine. A Failure Modes and Effects Analysis (FMEA) and a Technology Readiness Level (TRL) analysis have been completed resulting in the identification of high risk components within the design. The design has been analyzed from a commercial and economic point of view and Cost of Energy (COE) calculations have been carried out with the potential to reduce COE by up to 18% when compared with a permanent magnet direct drive 5MW baseline machine, resulting in a potential COE of 0.075 $/kWh. Finally, a top-level commercialization plan has been proposed to enable this technology to be transitioned to full volume production. The main body of this report will present the design processes employed and the main findings and conclusions.

R. Fair; W. Stautner; M. Douglass; R. Rajput-Ghoshal; M. Moscinski; P. Riley; D. Wagner; J. Kim; S. Hou; F. Lopez; K. Haran; J. Bray; T. Laskaris; J. Rochford; R. Duckworth

2012-10-12

416

Superconducting generators for wind turbines: Design considerations  

Microsoft Academic Search

The harmonic content of high temperature superconductors (HTS) field winding in air-core high temperature superconducting synchronous machine (HTS SM) has been addressed in order to investigate tendency of HTS SM towards mechanical oscillation and additional loss caused by higher flux harmonic. Both analytical expressions for flux distribution and current sheet distribution have been derived and analyzed. The two main contributors

N. Mijatovic; A. B. Abrahamsen; C. Træholt; E. Seiler; M. Henriksen; V. M. Rodriguez-Zermeno; N. F. Pedersen

2010-01-01

417

Harmonic control of multiple-stator induction machines for voltage regulation  

E-print Network

Small, one to a few horsepower, three-phase induction machines with three sets of electrically-isolated, magnetically-coupled stator winding circuits are described. A voltage inverter is developed and used to drive one set ...

Holloway, Jack Wade, 1980-

2004-01-01

418

The 100 kW experimental wind turbine generator project  

NASA Technical Reports Server (NTRS)

The Energy Research and Development Administration and the NASA Lewis Research Center engaged jointly in a Wind Energy Program which included the design and erection of a 100 kW wind turbine generator. This test machine consists of a rotor turbine, transmission, shaft, alternator, and tower. The rotor, measuring 125 feet in diameter and consisting of two variable pitch blades, operates at 40 rpm and generates 100 kW of electrical power at a wind velocity of 18 mph. The entire assembly is placed on top of a tower 100 feet above ground level. The machine was scheduled to be ready for operation in August, 1975.

Puthoff, R. L.; Sirocky, P.

1975-01-01

419

Finite element analyses of continuous filament ties for masonry applications:final report for the Arquin Corporation.  

SciTech Connect

Finite-element analyses were performed to simulate the response of a hypothetical masonry shear wall with and without continuous filament ties to various lateral loads. The loads represented three different scenarios: (1) 100 mph wind, (2) explosive attack, and (3) an earthquake. In addition, a static loading analysis and cost comparison were performed to evaluate optimal materials and designs for the spacers affixed to the filaments. Results showed that polypropylene, ABS, and polyethylene (high density) were suitable materials for the spacers based on performance and cost, and the short T-spacer design was optimal based on its performance and functionality. Results of the shear-wall loading simulations revealed that simulated walls with the continuous filament ties yielded factors of safety that were at least ten times greater than those without the ties. In the explosive attack simulation (100 psi), the simulated wall without the ties failed (minimum factor of safety was less than one), but the simulated wall with the ties yielded a minimum factor of safety greater than one. Simulations of the walls subject to lateral loads caused by 100 mph winds (0.2 psi) and seismic events with a peak ground acceleration of 1 ''g'' (0.66 psi) yielded no failures with or without the ties. Simulations of wall displacement during the seismic scenarios showed that the wall with the ties resulted in a maximum displacement that was 20% less than the wall without the ties.

Quinones, Armando (Arquin Corporation, La Luz, NM); Bibeau, Tiffany A.; Ho, Clifford Kuofei

2006-06-01

420

A MODULAR SHM-SCHEME FOR ENGINEERING STRUCTURES UNDER CHANGING CONDITIONS: APPLICATION TO AN OFFSHORE WIND  

E-print Network

TO AN OFFSHORE WIND TURBINE Moritz W. H¨ackell1, Raimund Rolfes1 1 Institute of Structural Analysis, Leibniz in common. A shift from fossil to renewable energy source is the logical con- sequence. (Offshore) wind : Offshore Wind Turbine, Machine Learning, Condition Parameter, Control Charts, Affinity Propagation

Paris-Sud XI, Université de

421

An examination of loads and responses of a wind turbine undergoing variable-speed operation  

Microsoft Academic Search

The National Renewable Energy Laboratory has recently developed the ability to predict turbine loads and responses for machines undergoing variable-speed operation. The wind industry has debated the potential benefits of operating wind turbine sat variable speeds for some time. Turbine system dynamic responses (structural response, resonance, and component interactions) are an important consideration for variable-speed operation of wind turbines. The

A. D. Wright; M. L. Jr. Buhl; G. S. Bir

1996-01-01

422

Pyruvate decarboxylase filaments are associated with the cortical cytoskeleton of asci and spores over the sexual cycle of filamentous ascomycetes.  

PubMed

We show that pyruvate decarboxylase (PDC) 8- to 10-nm-diameter filaments, first described in vegetative cells of Neurospora crassa, are ubiquitously present in filamentous fungi. The cellular arrangement of these structures was examined over the entire sexual cycle of the ascomycetes N. crassa, N. tetraesperma, Podospora anserina, and Sordaria macrospora. PDC-filaments were found associated with the cortical microtubule array of asci and ascospores and absent from the vicinity of spindles and spindle pole bodies. Nocodazole-induced depolymerization of the cortical microtubules results in the loss of PDC-filaments. Moreover, a S. macrospora mutant defective in cortical MT distribution shows abnormal PDC organization. Neurospora asci generated on various metabolic conditions, which modify the presence and relative abundance of PDC-filaments in vegetative cells, have identical patterns of subcellular distribution of these structures. A N. crassa mutant (snowflake) that accumulates giant bundles of PDC-filaments during vegetative growth, shows normal distribution of the filaments during ascogenesis. Thus, the regulation conditioning the presence and supramolecular assembly of PDC-filaments in Neurospora differs between vegetative and sexual cells. Taken together, these results suggest that PDC in filamentous fungi may perform two functions, intervening as an enzyme in vegetative metabolism and as a structural protein associated with the cytoskeleton during sexual development. PMID:10072321

Thompson-Coffe, C; Borioli, G; Zickler, D; Rosa, A L

1999-02-01

423

Proper horizontal photospheric flows in a filament channel  

NASA Astrophysics Data System (ADS)

Context. An extended filament in the central part of the active region NOAA 11106 crossed the central meridian on Sept. 17, 2010 in the southern hemisphere. It has been observed in H? with the THEMIS telescope in the Canary Islands and in 304 Å with the EUV imager (AIA) onboard the Solar Dynamic Observatory (SDO). Counterstreaming along the H? threads and bright moving blobs (jets) along the 304 Å filament channel were observed during 10 h before the filament erupted at 17:03 UT. Aims: The aim of the paper is to understand the coupling between magnetic field and convection in filament channels and relate the horizontal photospheric motions to the activity of the filament. Methods: An analysis of the proper photospheric motions using SDO/HMI continuum images with the new version of the coherent structure tracking (CST) algorithm developed to track granules, as well as the large scale photospheric flows, was performed for three hours. Using corks, we derived the passive scalar points and produced a map of the cork distribution in the filament channel. Averaging the velocity vectors in the southern hemisphere in each latitude in steps of 3.5 arcsec, we defined a profile of the differential rotation. Results: Supergranules are clearly identified in the filament channel. Diverging flows inside the supergranules are similar in and out of the filament channel. Converging flows corresponding to the accumulation of corks are identified well around the H? filament feet and at the edges of the EUV filament channel. At these convergence points, the horizontal photospheric velocity may reach 1 km s-1, but with a mean velocity of 0.35 km s-1. In some locations, horizontal flows crossing the channel are detected, indicating eventually large scale vorticity. Conclusions: The coupling between convection and magnetic field in the photosphere is relatively strong. The filament experienced the convection motions through its anchorage points with the photosphere, which are magnetized areas (ends, feet, lateral extensions of the EUV filament channel). From a large scale point-of-view, the differential rotation induced a shear of 0.1 km s-1 in the filament. From a small scale point-of-view, any convective motions favored the interaction of the parasitic polarities responsible for the anchorages of the filament to the photosphere with the surrounding network and may explain the activity of the filament. Two movies are available in electronic form at http://www.aanda.org

Schmieder, B.; Roudier, T.; Mein, N.; Mein, P.; Malherbe, J. M.; Chandra, R.

2014-04-01

424

Arrangements of actin filaments in the cytoskeleton of human platelets.  

PubMed Central

Assembly of actin molecules into filaments is closely associated with platelet shape change and exercise of contractile function. Since assembled actin filaments serve both as a framework for distortion of discoid shape and for generation of contractile force, it is important to determine the organizations of actin filaments capable of serving the two opposed functions of distortion and contraction. The present study has used negative staining alone and after combined glutaraldehyde fixation and detergent extraction to examine the arrangements of actin filaments in the cytoskeletons of surface activated platelets. Actin filament assembly developed as one of the earliest manifestations of platelet activation. Small protuberances containing random networks of actin filaments extending beyond the circumferential microtubules appeared to be an initial step in the response to stimulation. Transformation into dendritic forms was associated with development of parallel bundles of actin filaments organized into paracrystalline lattices with a periodicity of 5.5 nm at an angle of 60 degrees with the long axis of the pseudopod. Parallel bundles of actin filaments formed the concave borders of late dendritic forms and expanded to become the convex margin of most spread cells, suggesting a possible role in the spreading process. Other bundles of actin filaments resembled stress fibers radiating through the cytoplasm into pseudopods or organized in a variety of other apparently stable configurations. More loosely associated masses of actin filaments formed concentric layers around constricted rings of microtubules or a random network in the peripheral cytoplasm of spread cells. The arrangements of newly assembled actin filaments suggest their involvement in cell deformation, as well as contractile events. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 and 14 Figure 15 and 16 Figure 17 Figure 18 Figure 19 and 20 Figure 21 and 22 Figure 23 and 24 PMID:6149688

White, J. G.

1984-01-01

425

Mechanical Properties of Doubly Stabilized Microtubule Filaments  

PubMed Central

Microtubules are cytoskeletal filaments responsible for cell morphology and intracellular organization. Their dynamical and mechanical properties are regulated through the nucleotide state of the tubulin dimers and the binding of drugs and/or microtubule-associated proteins. Interestingly, microtubule-stabilizing factors have differential effects on microtubule mechanics, but whether stabilizers have cumulative effects on mechanics or whether one effect dominates another is not clear. This is especially important for the chemotherapeutic drug Taxol, an important anticancer agent and the only known stabilizer that reduces the rigidity of microtubules. First, we ask whether Taxol will combine additively with another stabilizer or whether one stabilizer will dominate another. We call microtubules in the presence of Taxol and another stabilizer, doubly stabilized. Second, since Taxol is often added to a number of cell types for therapeutic purposes, it is important from a biomedical perspective to understand how Taxol added to these systems affects the mechanical properties in treated cells. To address these questions, we use the method of freely fluctuating filaments with our recently developed analysis technique of bootstrapping to determine the distribution of persistence lengths of a large population of microtubules treated with different stabilizers, including Taxol, guanosine-5? [(?, ?)-methyleno] triphosphate, guanosine-5?-O-(3-thiotriphosphate), tau, and MAP4. We find that combinations of these stabilizers have novel effects on the mechanical properties of microtubules. PMID:23561528

Hawkins, Taviare L.; Sept, David; Mogessie, Binyam; Straube, Anne; Ross, Jennifer L.

2013-01-01

426

The filamentous fungal gene expression database (FFGED).  

PubMed

Filamentous fungal gene expression assays provide essential information for understanding systemic cellular regulation. To aid research on fungal gene expression, we constructed a novel, comprehensive, free database, the filamentous fungal gene expression database (FFGED), available at http://bioinfo.townsend.yale.edu. FFGED features user-friendly management of gene expression data, which are assorted into experimental metadata, experimental design, raw data, normalized details, and analysis results. Data may be submitted in the process of an experiment, and any user can submit multiple experiments, thus classifying the FFGED as an "active experiment" database. Most importantly, FFGED functions as a collective and collaborative platform, by connecting each experiment with similar related experiments made public by other users, maximizing data sharing among different users, and correlating diverse gene expression levels under multiple experimental designs within different experiments. A clear and efficient web interface is provided with enhancement by AJAX (Asynchronous JavaScript and XML) and through a collection of tools to effectively facilitate data submission, sharing, retrieval and visualization. PMID:20025988

Zhang, Zhang; Townsend, Jeffrey P

2010-03-01

427

Optimisation of machining parameters of glass-fibre-reinforced plastic (GFRP) pipes by desirability function analysis using Taguchi technique  

Microsoft Academic Search

This paper presents a new approach for optimizing the machining parameters on turning glass-fibre-reinforced plastic (GFRP)\\u000a pipes. Optimisation of machining parameters was done by an analysis called desirability function analysis, which is a useful\\u000a tool for optimizing multi-response problems. In this work, based on Taguchi’s L18 orthogonal array, turning experiments were conducted for filament wound and hand layup GFRP pipes

A. Naveen Sait; S. Aravindan; A. Noorul Haq

2009-01-01

428

Cutting forces and wear analysis of Si 3N 4 diamond coated tools in high speed machining  

Microsoft Academic Search

Si3N4 tools were coated with a thin diamond film using a Hot-Filament Chemical Vapour Deposition (HFCVD) reactor, in order to machining a grey cast iron. Wear behaviour of these tools in high speed machining was the main subject of this work. Turning tests were performed with a combination of cutting speeds of 500, 700 and 900mmin?1, and feed rates of

R. P. Martinho; F. J. G. Silva; A. P. M. Baptista

2008-01-01

429

Wire electric-discharge machining and other fabrication techniques  

NASA Technical Reports Server (NTRS)

Wire electric discharge machining and extrude honing were used to fabricate a two dimensional wing for cryogenic wind tunnel testing. Electric-discharge cutting is done with a moving wire electrode. The cut track is controlled by means of a punched-tape program and the cutting feed is regulated according to the progress of the work. Electric-discharge machining involves no contact with the work piece, and no mechanical force is exerted. Extrude hone is a process for honing finish-machined surfaces by the extrusion of an abrasive material (silly putty), which is forced through a restrictive fixture. The fabrication steps are described and production times are given.

Morgan, W. H.

1983-01-01

430

Phytoplankton pigment patterns and wind forcing off central California  

NASA Technical Reports Server (NTRS)

Mesoscale variability in phytoplankton pigment distributions of central California during the spring-summer upwelling season are studied via a 4-yr time series of high-resolution coastal zone color scanner imagery. Empirical orthogonal functions are used to decompose the time series of spatial images into its dominant modes of variability. The coupling between wind forcing of the upper ocean and phytoplankton distribution on mesoscales is investigated. Wind forcing, in particular the curl of the wind stress, was found to play an important role in the distribution of phytoplankton pigment in the California Current. The spring transition varies in timing and intensity from year to year but appears to be a recurrent feature associated with the rapid onset of the upwelling-favorable winds. Although the underlying dynamics may be dominated by processes other than forcing by wind stress curl, it appears that curl may force the variability of the filaments and hence the pigment patterns.

Abbott, Mark R.; Barksdale, Brett

1991-01-01

431

Wind energy utilization: A bibliography with abstracts - Cumulative volume 1944/1974  

NASA Technical Reports Server (NTRS)

Bibliography, up to 1974 inclusive, of articles and books on utilization of wind power in energy generation. Worldwide literature is surveyed, and short abstracts are provided in many cases. The citations are grouped by subject: (1) general; (2) utilization; (3) wind power plants; (4) wind power generators (rural, synchronous, remote station); (5) wind machines (motors, pumps, turbines, windmills, home-built); (6) wind data and properties; (7) energy storage; and (8) related topics (control and regulation devices, wind measuring devices, blade design and rotors, wind tunnel simulation, aerodynamics). Gross-referencing is aided by indexes of authors, corporate sources, titles, and keywords.

1975-01-01

432

The NASA Lewis large wind turbine program  

NASA Technical Reports Server (NTRS)

The program is directed toward development of the technology for safe, reliable, environmentally acceptable large wind turbines that have the potential to generate a significant amount of electricity at costs competitive with conventional electric generation systems. In addition, these large wind turbines must be fully compatible with electric utility operations and interface requirements. Advances are made by gaining a better understanding of the system design drivers, improvements in the analytical design tools, verification of design methods with operating field data, and the incorporation of new technology and innovative designs. An overview of the program activities is presented and includes results from the first and second generation field machines (Mod-OA, -1, and -2), the design phase of the third generation wind turbine (Mod-5) and the advanced technology projects. Also included is the status of the Department of Interior WTS-4 machine.

Thomas, R. L.; Baldwin, D. H.

1981-01-01

433

The Mod-2 wind turbine development project  

NASA Technical Reports Server (NTRS)

A major phase of the Federal Wind Energy Program, the Mod-2 wind turbine, a second-generation machine developed by the Boeing Engineering and Construction Co. for the U.S. Department of Energy and the Lewis Research Center of the National Aeronautics and Space Administration, is described. The Mod-2 is a large (2.5-MW power rating) horizontal-axis wind turbine designed for the generation of electrical power on utility networks. Three machines were built and are located in a cluster at Goodnoe Hills, Washington. All technical aspects of the project are described: design approach, significant innovation features, the mechanical system, the electrical power system, the control system, and the safety system.

Linscott, B. S.; Dennett, J. T.; Gordon, L. H.

1981-01-01

434

Stability and evolution of kinetic current-vortex filaments Hugo J. de Blank  

E-print Network

Stability and evolution of kinetic current-vortex filaments Hugo J. de Blank FOM-Instituut voor interactions between filaments. The linear stability of a large class of current- vortex filament solutions

435

Method for simultaneously coating a plurality of filaments  

DOEpatents

Methods and apparatuses for coating materials, and the products and compositions produced thereby. Substances, such as diamond or diamond-like carbon, are deposited onto materials, such as a filament or a plurality of filaments simultaneously, using one or more cylindrical, inductively coupled, resonator plasma reactors.

Miller, Paul A. (1004 Matia Ct. NE., Albuquerque, NM 87123); Pochan, Paul D. (3308 Morris St. NE., #11, Albuquerque, NM 87111); Siegal, Michael P. (9900 Spain NE., Apt. W-2123, Albuquerque, NM 87111); Dominguez, Frank (11341 Academy Ridge Rd. NE., Albuquerque, NM 87111)

1995-01-01

436

Probing the cosmic web: intercluster filament detection using gravitational lensing  

Microsoft Academic Search

The problem of detecting dark matter filaments in the cosmic web is considered. Weak lensing is an ideal probe of dark matter, and therefore forms the basis of particularly promising detection methods. We consider and develop a number of weak lensing techniques that could be used to detect filaments in individual or stacked cluster fields, and apply them to synthetic

James M. G. Mead; Lindsay J. King; Ian G. McCarthy

2010-01-01

437

Galaxy Spin Alignment in Filaments and Sheets: Observational Evidence  

NASA Astrophysics Data System (ADS)

The properties of galaxies are known to be affected by their environment. One important question is how their angular momentum reflects the surrounding cosmic web. We use the Sloan Digital Sky Survey to investigate the spin axes of spiral and elliptical galaxies relative to their surrounding filament/sheet orientations. To detect filaments, a marked point process with interactions (the "Bisous model") is used. Sheets are found by detecting "flattened" filaments. The minor axes of ellipticals are found to be preferentially perpendicular to hosting filaments. A weak correlation is found with sheets. These findings are consistent with the notion that elliptical galaxies formed via mergers, which predominantly occurred along the filaments. The spin axis of spiral galaxies is found to align with the host filament, with no correlation between spiral spin and sheet normal. When examined as a function of distance from the filament axis, a much stronger correlation is found in the outer parts, suggesting that the alignment is driven by the laminar infall of gas from sheets to filaments. When compared with numerical simulations, our results suggest that the connection between dark matter halo and galaxy spin is not straightforward. Our results provide an important input to the understanding of how galaxies acquire their angular momentum.

Tempel, Elmo; Libeskind, Noam I.

2013-10-01

438

GALAXY SPIN ALIGNMENT IN FILAMENTS AND SHEETS: OBSERVATIONAL EVIDENCE  

SciTech Connect

The properties of galaxies are known to be affected by their environment. One important question is how their angular momentum reflects the surrounding cosmic web. We use the Sloan Digital Sky Survey to investigate the spin axes of spiral and elliptical galaxies relative to their surrounding filament/sheet orientations. To detect filaments, a marked point process with interactions (the {sup B}isous model{sup )} is used. Sheets are found by detecting 'flattened' filaments. The minor axes of ellipticals are found to be preferentially perpendicular to hosting filaments. A weak correlation is found with sheets. These findings are consistent with the notion that elliptical galaxies formed via mergers, which predominantly occurred along the filaments. The spin axis of spiral galaxies is found to align with the host filament, with no correlation between spiral spin and sheet normal. When examined as a function of distance from the filament axis, a much stronger correlation is found in the outer parts, suggesting that the alignment is driven by the laminar infall of gas from sheets to filaments. When compared with numerical simulations, our results suggest that the connection between dark matter halo and galaxy spin is not straightforward. Our results provide an important input to the understanding of how galaxies acquire their angular momentum.

Tempel, Elmo [Tartu Observatory, Observatooriumi 1, 61602 Tõravere (Estonia)] [Tartu Observatory, Observatooriumi 1, 61602 Tõravere (Estonia); Libeskind, Noam I., E-mail: elmo@to.ee, E-mail: nlibeskind@aip.de [Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam (Germany)

2013-10-01

439

Dynamics of filamentous viral RNPs prior to egress  

Microsoft Academic Search

The final step in the maturation of paramyxoviruses, orthomyxoviruses and viruses of several other families, entails the budding of the viral nucleo- capsid through the plasma membrane of the host cell. Many medically important viruses, such as influenza, parainfluenza, respiratory syncytial virus (RSV) and Ebola, can form filamentous particles when budding. Although filamentous virions have been previously studied, details of

Philip J. Santangelo; Gang Bao

2007-01-01

440

Process for the production of superconductor containing filaments  

DOEpatents

Superconductor containing filaments having embedments of superconducting material surrounded by a rayon matrix are formed by preparing a liquid suspension which contains at least 10 weight percent superconducting material; forming a multicomponent filament having a core of the suspension and a viscose sheath which contains cellulose xanthate; and thereafter, regenerating cellulose from the cellulose xanthate to form a rayon matrix.

Tuominen, Olli P. (Candler, NC); Hoyt, Matthew B. (Arden, NC); Mitchell, David F. (Asheville, NC); Morgan, Carol W. (Asheville, NC); Roberts, Clyde Gordon (Asheville, NC); Tyler, Robert A. (Canton, NC)

2002-01-01

441

The effect of delays on filament oscillations and stability  

NASA Astrophysics Data System (ADS)

We discuss the linear response of a filament to perturbations, taking the finite communication time between the filament and the photosphere into account. The finite communication time introduces delays in the system. Recently Schutgens (1997ab) investigated the solutions of the delay equation for vertical perturbations. In this paper we expand his analysis by considering also horizontal and coupled oscillations. The latter occur in asymmetric coronal fields. We also discuss the effect of Alfven wave emission on filament oscillations and show that wave emission is important for stabilizing filaments. We introduce a fairly straightforward method to study the solutions of delay equations as a function of the filament-photosphere communication time. A solution can be described by a linear combination of damped harmonic oscillations each characterized by a frequency, a damping/growth time and, accordingly, a quality factor. As a secondary result of our analysis we show that, within the context of line current models, Kippenhahn/Schlüter-type filament equilibria can never be stable in the horizontal and the vertical direction at the same time but we also demonstrate that Kuperus/Raadu-type equilibria can account for both an inverse or a normal polarity signature. The diagnostic value of our analysis for determining, e.g., the filament current from observations of oscillating filaments is discussed.

van den Oord, G. H. J.; Schutgens, N. A. J.; Kuperus, M.

1998-11-01

442

ATP Hydrolysis Stimulates Large Length Fluctuations in Single Actin Filaments  

E-print Network

ATP Hydrolysis Stimulates Large Length Fluctuations in Single Actin Filaments Evgeny B. Stukalin is investigated theoretically using a stochastic model that takes into account the hydrolysis of ATP filaments. It is found that the ATP hydrolysis has a strong effect on dynamic properties of single actin

443

Fine filament NbTi conductors for the SSC  

Microsoft Academic Search

In support of the SSC magnet development program, IGC-Advanced Superconductors, Inc. has produced over 4500 lbs of fine filament wire. Since the SSC would require a large volume production at the most economical price, billets measuring 12'' dia have been used for this prototype wire production. Both inner and outer grades of wire have been processed with NbTi filament diameters

H. C. Kanithi; C. G. King; B. A. Zeitlin; R. M. Scanlan

1989-01-01

444

Coupling Losses in Superconductors With Twisted Filaments, Stripes, or Striations  

Microsoft Academic Search

All contributions to coupling losses in superconducting flat structures with twisted filaments, stripes or striations with different normal conducting central parts are summarized. It is shown that in some structures the contribution, caused by the induced currents between filaments, stripes or striations on the same side of a flat tape or cable, can be decisive for the total coupling losses.

S. Takacs

2007-01-01

445

Acoustic Emission from Single and Multiple Kevlar 49 Filament Breaks  

Microsoft Academic Search

Acoustic Emission (AE) was monitored during single filament tension tests of Kevlar 49 fiber. AE was also monitored during dry and lubricated bundle tests of the same material. These later tests were carried out in such a way that the individual filament breaks could be independently verified. Statistical studies were made of the AE event characterization parameters for the source

Marvin A. Hamstad; Richard L. Moore

1986-01-01

446

Statistical properties of filaments in weak gravitational lensing  

NASA Astrophysics Data System (ADS)

We study the weak lensing properties of filaments that connect clusters of galaxies through large cosmological N-body simulations. We select 4639 halo pairs with masses higher than 1014 h-1 M? from the simulations and investigate dark matter distributions between two haloes with ray-tracing simulations. In order to classify filament candidates, we estimate convergence profiles and perform profile fitting. We find that matter distributions between haloes can be classified in a plane of fitting parameters, which allows us to select straight filaments from the ray-tracing simulations. We also investigate the statistical properties of these filaments, finding them to be consistent with previous studies. We find that 35 per cent of halo pairs possess straight filaments, 4 per cent of which can be detected directly at signal-to-noise ratio S/N ? 2 with weak lensing. Furthermore, we study the statistical properties of haloes at the edges of filaments. We find that haloes are preferentially elongated along filamentary structures and are less massive with increasing filament mass. However, the dependence of these halo properties on the masses of straight filaments is very weak.

Higuchi, Yuichi; Oguri, Masamune; Shirasaki, Masato

2014-06-01

447

Biophysics of filament length regulation by molecular motors  

NASA Astrophysics Data System (ADS)

Regulating physical size is an essential problem that biological organisms must solve from the subcellular to the organismal scales, but it is not well understood what physical principles and mechanisms organisms use to sense and regulate their size. Any biophysical size-regulation scheme operates in a noisy environment and must be robust to other cellular dynamics and fluctuations. This work develops theory of filament length regulation inspired by recent experiments on kinesin-8 motor proteins, which move with directional bias on microtubule filaments and alter microtubule dynamics. Purified kinesin-8 motors can depolymerize chemically-stabilized microtubules. In the length-dependent depolymerization model, the rate of depolymerization tends to increase with filament length, because long filaments accumulate more motors at their tips and therefore shorten more quickly. When balanced with a constant filament growth rate, this mechanism can lead to a fixed polymer length. However, the mechanism by which kinesin-8 motors affect the length of dynamic microtubules in cells is less clear. We study the more biologically realistic problem of microtubule dynamic instability modulated by a motor-dependent increase in the filament catastrophe frequency. This leads to a significant decrease in the mean filament length and a narrowing of the filament length distribution. The results improve our understanding of the biophysics of length regulation in cells.

Kuan, Hui-Shun; Betterton, M. D.

2013-06-01

448

Biophysics of filament length regulation by molecular motors  

E-print Network

Regulating physical size is an essential problem that biological organisms must solve from the subcellular to the organismal scales, but it is not well understood what physical principles and mechanisms organisms use to sense and regulate their size. Any biophysical size-regulation scheme operates in a noisy environment and must be robust to other cellular dynamics and fluctuations. This work develops theory of filament length regulation inspired by recent experiments on kinesin-8 motor proteins, which move with directional bias on microtubule filaments and alter microtubule dynamics. Purified kinesin-8 motors can depolymerize chemically-stabilized microtubules. In the length-dependent depolymerization model, the rate of depolymerization tends to increase with filament length, because long filaments accumulate more motors at their tips and therefore shorten more quickly. When balanced with a constant filament growth rate, this mechanism can lead to a fixed polymer length. However, the mechanism by which kinesin-8 motors affect the length of dynamic microtubules in cells is less clear. We study the more biologically realistic problem of microtubule dynamic instability modulated by a motor-dependent increase in the filament catastrophe frequency. This leads to a significant decrease in the mean filament length and a narrowing of the filament length distribution. The results improve our understanding of the biophysics of length regulation in cells.

Hui-Shun Kuan; M. D. Betterton

2013-02-13

449

Helical order in tarantula thick filaments requires the \\  

Microsoft Academic Search

Myosin heads are helically ordered on the thick filament surface in relaxed muscle. In mammalian and avian filaments this helical arrangement is dependent on temperature and it has been suggested that helical order is related to ATP hydrolysis by the heads. To test this hypothesis, we have used electron microscopy and image analysis to study the ability and temperature dependence

M. E. Zoghbi; J. L. Woodhead; R. Craig; R. Padron

2004-01-01

450

Dissection of Filamentous Growth by Transposon Mutagenesis in Saccharomyces Cerevisiae  

PubMed Central

Diploid Saccharomyces cerevisiae strains starved for nitrogen undergo a developmental transition from growth as single yeast form (YF) cells to a multicellular form consisting of filaments of pseudohyphal (PH) cells. Filamentous growth is regulated by an evolutionarily conserved signaling pathway that includes the small GTP-binding proteins Ras2p and Cdc42p, the protein kinases Ste20p, Ste11p and Ste7p, and the transcription factor Ste12p. Here, we designed a genetic screen for mutant strains defective for filamentous growth (dfg) to identify novel targets of the filamentation signaling pathway, and we thereby identified 16 different genes, CDC39, STE12, TEC1, WHI3, NAB1, DBR1, CDC55, SRV2, TPM1, SPA2, BNI1, DFG5, DFG9, DFG10, BUD8 and DFG16, mutations that block filamentous growth. Phenotypic analysis of dfg mutant strains genetically dissects filamentous growth into the cellular processes of signal transduction, bud site selection, cell morphogenesis and invasive growth. Epistasis tests between dfg mutant alleles and dominant activated alleles of the RAS2 and STE11 genes, RAS2(Val19) and STE11-4, respectively, identify putative targets for the filamentation signaling pathway. Several of the genes described here have homologues in filamentous fungi, where they also regulate fungal development. PMID:9055077

Mosch, H. U.; Fink, G. R.

1997-01-01

451

Galactic Winds  

NASA Astrophysics Data System (ADS)

Galactic winds have become arguably one of the hottest topics in extragalactic astronomy. This enthusiasm for galactic winds is due in part to the detection of winds in many, if not most, high-redshift galaxies. Galactic winds have also been invoked by theorists to (1) suppress the number of visible dwarf galaxies and avoid the "cooling catastrophe" at high redshift that results in the overproduction of massive luminous galaxies, (2) remove material with low specific angular momentum early on and help enlarge gas disks in CDM + baryons simulations, (3) reduce the dark mass concentrations in galaxies, (4) explain the mass-metallicity relation of galaxies from selective loss of metal-enriched gas from smaller galaxies, (5) enrich and "preheat" the ICM, (6) enrich the IGM without disturbing the Ly?forest significantly, and (7) inhibit cooling flows in galaxy clusters with active cD galaxies. The present paper highlights a few key aspects of galactic winds taken from a recent ARAA review by Veilleux, Cecil, &Bland-Hawthorn (2005; herafter VCBH). Readers interested in a more detailed discussion of this topic are encouraged to refer to the original ARAA article.

Veilleux, Sylvain

452

Composite rotor blades for wind turbine generators  

NASA Astrophysics Data System (ADS)

The materials, techniques, and methods used to construct a 150 ft test blade, two 31 ft blades for a 40 kW WECS, and rotor blades for the Mod-1 wind turbine are described. Considerations of strength, stiffness, and mass distributions, as well as cost, led to the choice of filament wound fiberglass/epoxy material using transverse filament tape which has structural fibers running across the width of the tape. A number of 90 deg windings were added to the rotor after tape winding to provide compaction and hoop strength. Curing comprised five hours at 180 F. The Mod-1 blades were required to match the steel blades in weight, stiffness, deflection, and frequencies. The finished product weighed 20,000 lb and featured a metal tip cap and braided wire trailing edge strap for lightning protection. The 40 kW was a NACA 23018 in the center and 23012 at the tip, while the Mod-1 blade was a NACA 23025 in the center and 23015 at the tip.

Weigel, W. D.

453

Wind tower augmentation of wind turbines  

Microsoft Academic Search

The operating principle of the 'Baud-Geers' wind towers traditionally used in Iran for ventilation and passive cooling of architectural structures is presently adapted to house a vertical axis wind turbine. Unlike annular diffuser-augmented, horizontal axis wind turbines, the 'wind tower' does not have to be trained into the wind and generates less noise. It may also be either free standing

M. N. Bahadori

1984-01-01

454

Perspex machine: VII. The universal perspex machine  

NASA Astrophysics Data System (ADS)

The perspex machine arose from the unification of projective geometry with the Turing machine. It uses a total arithmetic, called transreal arithmetic, that contains real arithmetic and allows division by zero. Transreal arithmetic is redefined here. The new arithmetic has both a positive and a negative infinity which lie at the extremes of the number line, and a number nullity that lies off the number line. We prove that nullity, 0/0, is a number. Hence a number may have one of four signs: negative, zero, positive, or nullity. It is, therefore, impossible to encode the sign of a number in one bit, as floating-point arithmetic attempts to do, resulting in the difficulty of having both positive and negative zeros and NaNs. Transrational arithmetic is consistent with Cantor arithmetic. In an extension to real arithmetic, the product of zero, an infinity, or nullity with its reciprocal is nullity, not unity. This avoids the usual contradictions that follow from allowing division by zero. Transreal arithmetic has a fixed algebraic structure and does not admit options as IEEE, floating-point arithmetic does. Most significantly, nullity has a simple semantics that is related to zero. Zero means "no value" and nullity means "no information." We argue that nullity is as useful to a manufactured computer as zero is to a human computer. The perspex machine is intended to offer one solution to the mind-body problem by showing how the computable aspects of mind and, perhaps, the whole of mind relates to the geometrical aspects of body and, perhaps, the whole of body. We review some of Turing's writings and show that he held the view that his machine has spatial properties. In particular, that it has the property of being a 7D lattice of compact spaces. Thus, we read Turing as believing that his machine relates computation to geometrical bodies. We simplify the perspex machine by substituting an augmented Euclidean geometry for projective geometry. This leads to a general-linear perspex-machine which is very much easier to program than the original perspex-machine. We then show how to map the whole of perspex space into a unit cube. This allows us to construct a fractal of perspex machines with the cardinality of a real-numbered line or space. This fractal is the universal perspex machine. It can solve, in unit time, the halting problem for itself and for all perspex machines instantiated in real-numbered space, including all Turing machines. We cite an experiment that has been proposed to test the physical reality of the perspex machine's model of time, but we make no claim that the physical universe works this way or that it has the cardinality of the perspex machine. We leave it that the perspex machine provides an upper bound on the computational properties of physical things, including manufactured computers and biological organisms, that have a cardinality no greater than the real-number line.

Anderson, James A. D. W.

2006-01-01

455

Ultrasonic analysis of Kevlar-epoxy filament wound structures  

NASA Astrophysics Data System (ADS)

Composite structures are often desirable for their strength and weight characteristics. Since composites are not as well characterized mechanically as metallic or ceramic structures, much work has been performed at the Oak Ridge Y-12 Plant to obtain that characterization and to develop methods of determining the mechanical properties of a composite nondestructively. Most of the work to date has been performed on nonenclosed structures. One notable exception has been the holographic evaluation of spherical Kevlar-epoxy composite pressure vessels. Several promising nondestructive evaluation techniques have been used to locate flaws and predict the integrity of the composite. Several of these include thermography, Moire interferometry, ultrasonic stress wave factor, ultrasonic C-scan image enhancement, radiography, and nuclear magnetic resonance. As a first step in this transfer and development of NDE techniques, known defects were placed within spherical Kevlar-epoxy, filament-wound test specimens to determine the extent to which they could be detected. These defects included Teflon shim-simulated delaminations, macrosphere-simulated voids, dry-band sets, variable tension, Kevlar 29 fiber instead of the higher strength Kevlar 40 fiber, and an alternate high-void-content winding pattern. Ultrasonic waveform analysis was performed in both the time and frequency domains to determine the detectability and locatability of structural flaws within the composite. Preparation has been made at Virginia Polytechnic Institute and State University and at the University of Delaware, to examine the specimens using various NDE techniques. This work is a compilation of interim project reports in partial fulfillment of the contracts between Virginia Polytechnic Institute and State University, the University of Delaware, and Y-12 Plant.

Brosey, W. D.

1985-07-01

456

Condensation of actin filaments pushing against a barrier  

E-print Network

We develop a model to describe the force generated by the polymerization of an array of parallel biofilaments. The filaments are assumed to be coupled only through mechanical contact with a movable barrier. We calculate the filament density distribution and the force-velocity relation with a mean-field approach combined with simulations. We identify two regimes: a non-condensed regime at low force in which filaments are spread out spatially, and a condensed regime at high force in which filaments accumulate near the barrier. We confirm a result previously known from other related studies, namely that the stall force is equal to N times the stall force of a single filament. In the model studied here, the approach to stalling is very slow, and the velocity is practically zero at forces significantly lower than the stall force.

K. Tsekouras; D. Lacoste; K. Mallick; J. -F. Joanny

2011-01-06

457

Impact of motor molecules on the dynamics of treadmilling filaments  

NASA Astrophysics Data System (ADS)

We study a driven lattice gas model for the length dynamics of treadmilling filaments in the presence of molecular motors. A treadmilling filament grows by subunit addition at one end and shrinks by subunit removal at the other. Molecular motors can attach to the filament, move towards the shrinking end, and detach from the filament. We consider motors that are also capable of inducing subunit removal at the shrinking filament end. Stochastic simulations reveal a phase of unimodal length distribution and a phase of unbounded growth. Exploiting a condition on the motor flux, we explore the system's phase diagram. In certain limits we can define random walks that allow us to estimate the full length distribution. The width of steady state distributions decreases with increasing motor activity. Our analysis indicates possible ways that cells can use to regulate the size of cytoskeletal structures such as mitotic spindles by controlling various motor properties.

Erlenkämper, Christoph; Johann, Denis; Kruse, Karsten

2012-11-01

458

The extreme nonlinear optics of gases and femtosecond optical filamentation  

SciTech Connect

Under certain conditions, powerful ultrashort laser pulses can form greatly extended, propagating filaments of concentrated high intensity in gases, leaving behind a very long trail of plasma. Such filaments can be much longer than the longitudinal scale over which a laser beam typically diverges by diffraction, with possible applications ranging from laser-guided electrical discharges to high power laser propagation in the atmosphere. Understanding in detail the microscopic processes leading to filamentation requires ultrafast measurements of the strong field nonlinear response of gas phase atoms and molecules, including absolute measurements of nonlinear laser-induced polarization and high field ionization. Such measurements enable the assessment of filamentation models and make possible the design of experiments pursuing applications. In this paper, we review filamentation in gases and some applications, and discuss results from diagnostics developed at Maryland for ultrafast measurements of laser-gas interactions.

Milchberg, H. M.; Chen, Y.-H.; Cheng, Y.-H.; Jhajj, N.; Palastro, J. P.; Rosenthal, E. W.; Varma, S.; Wahlstrand, J. K.; Zahedpour, S. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States)

2014-10-15

459

Critical current density and dissipation in sintered YBCO filaments  

SciTech Connect

Critical current density and dissipation of four sintered YBCO filaments were measured using a continuous DC power supply. Each sample exhibited somewhat different characteristics from the others even though 3 of the 4 samples are from the same batch. The data suggest that it is possible for the YBCO filament to be in a state of stable equilibrium when part of the filament is in the flux-flow state and part of the filament is in the normal state (local hot spots). This behavior may be advantageous for resistive fault current limiters because the intermediate state (partly flux-flow and partly normal) has an overall resistance much higher than that of the flux-flow state but it does not lead to thermal runaway (burnout) or excessive heating compared to a YBCO filament driven into normal state over its entire length. Two of the samples were broken as a result of local burnout.

Cha, Y.S.; Hull, J.R. [Argonne National Lab., IL (United States); Seol, S.Y. [Chonnam National Univ., Kwangju (Korea, Republic of)

1997-09-01

460

Femtosecond filamentation induced fluorescence technique for atmospheric sensing  

NASA Astrophysics Data System (ADS)

Recent progress in filament-induced atmospheric sensing is reviewed. Self-guided propagation of ultrashort laser pulses in air induces laser filamentation. All molecules in the path of a filament can be dissociated into highly excited fragments, resulting in emission of characteristic fluorescence spectra. The fluorescence spectra provide information about the various molecules in the filaments. By using a filament-induced “fingerprinting” fluorescence technique, molecules in the atmosphere can be identified. Project supported by the National Basic Research Program of China (Grant No. 2011CB808105), the International Science and Technology Collaboration Program, China (Grant Nos. 2010DFA04410 and 11530700900), the National Key Scientific Instrument Project (Grant No. 2012YQ150092), and the Canada Research Chair, Natural Sciences and Engineering Research Council of Canada, Canada Foundation for Innovation, Canadian Institute for Photonics Innovation and le FQRNT.

Yuan, Shuai; Chin, See Leang; Zeng, He-Ping

2015-01-01

461

Wind turbine  

DOEpatents

A wind turbine of the type having an airfoil blade (15) mounted on a flexible beam (20) and a pitch governor (55) which selectively, torsionally twists the flexible beam in response to wind turbine speed thereby setting blade pitch, is provided with a limiter (85) which restricts unwanted pitch change at operating speeds due to torsional creep of the flexible beam. The limiter allows twisting of the beam by the governor under excessive wind velocity conditions to orient the blades in stall pitch positions, thereby preventing overspeed operation of the turbine. In the preferred embodiment, the pitch governor comprises a pendulum (65,70) which responds to changing rotor speed by pivotal movement, the limiter comprising a resilient member (90) which engages an end of the pendulum to restrict further movement thereof, and in turn restrict beam creep and unwanted blade pitch misadjustment.

Cheney, Jr., Marvin C. (Glastonbury, CT)

1982-01-01

462

Analytical Model of Magnet Eddy-Current Volume Losses in Multi-phase PM Machines  

E-print Network

Analytical Model of Magnet Eddy-Current Volume Losses in Multi-phase PM Machines with Concentrated, 94000 Créteil France Abstract--this paper studies magnet eddy-current losses in permanent magnet (PM calculations. Keywords--Traction, Concentrated Winding, Eddy- Current, Volume Magnet Losses, Multiphase Machine

Paris-Sud XI, Université de

463

Filament formation in Saccharomyces cerevisiae--a review.  

PubMed

Many yeasts can produce filamentous elongated cells identifiable as hyphae, pseudohyphae or invasive filaments. Filament formation has been understood as a foraging response that occurs in nutrient-poor conditions. However, fusel alcohols were observed to induce filament formation in rich nutrient conditions in every yeast species examined. Fusel alcohols, e.g., 3-methyl-1-butanol (3Me-BuOH; 'isoamyl alcohol'), 2-methyl-1-propanol (isobutyl alcohol), (-)-2-methyl-1-butanol ('active amyl alcohol'), 2-phenylethanol and 3-(2-hydroxyethyl)indole (tryptophol) (the end products of leucine, valine, isoleucine, phenylalanine and tryptophan catabolism, respectively) are the end products of amino acid catabolism that accumulate when nutrients become limiting. Thus, yeast responds to its own metabolic by-products. Considerable effort was made to define the cell biological and biochemical changes that take place during 3Me-BuOH-induced filamentation. In Saccharomyces cerevisiae filaments contain significantly greater mitochondrial mass and increased chitin content in comparison with yeast-form cells. The global transcriptional response of S. cerevisiae during the early stages of 3Me-BuOH-induced filament formation has been described. Four ORFs displayed very significant (more than 10-fold) increases in their RNA species, and 12 ORFs displayed increases in transcription of more than 5-fold. The transcription of five genes (all of which encode transporters) decreased by similar amounts. Where examined, the activity of the proteins encoded reflected the transcriptional pattern of their respective mRNAs. To understand this regulation, studies were performed to see whether deletion or overexpression of key genes affects the ability to filament and invade solid YEPD medium. This has led to identification of those proteins that are essential for filament formation, repressors and those which are simply not required. It also leads to the conclusion that 3Me-BuOH-induced filament formation is not a foraging response but a response to reduced growth rate. PMID:18481212

Dickinson, J R

2008-01-01

464

TRACE and SVST Observations of an Active-Region Filament  

NASA Astrophysics Data System (ADS)

In June 1998 the Transition Region and Coronal Explorer (TRACE) observed filaments and prominences in coordination with various ground-based solar observatories, including the Swedish Vacuum Solar Telescope (SVST) on La Palma. Here we present results for an active-region filament observed on June 21-22. This horse-shoe shaped filament had a "barb" that reached down from the filament spine to the chomosphere below. We use high-resolution images obtained at the SVST on June 21 from 18:03 to 19:04 UT to study the fine structure and dynamics of plasmas in the barb and other parts of the filament. The data consist of narrowband H? images taken with the Lockheed Tunable Filtergraph operating at a cadence of 20 s. We present Doppler maps derived from these images. The filament erupted six hours after the SVST observations. The eruption was observed with TRACE, which obtained images in Fe IX/X 171, Fe XII 195, Fe XV 284 and H I Lyalpha . At the start of the event, a thin bright loop appears high above the filament at the location of the barb. We interpret this feature as the outline of a magnetic "bubble" which forms as a result of kink instability in the magnetic field that supports the filament. The bright loop appears to be due to particle acceleration and impulsive heating along certain field lines on the periphery of this magnetic structure. A few minutes later, the dark filament threads turn into emission and move outward, exhibiting a helical structure. We discuss the magnetic structure of the barb and its possible role in the filament eruption.

van Ballegooijen, A. A.; Deluca, E. E.

1999-05-01

465

Apparatus For Laminating Segmented Core For Electric Machine  

DOEpatents

A segmented core for an electric machine includes segments stamped from coated electric steel. The segments each have a first end, a second end, and winding openings. A predetermined number of segments are placed end-to-end to form layers. The layers are stacked such that each of the layers is staggered from adjacent layers by a predetermined rotation angle. The winding openings of each of the layers are in vertical alignment with the winding openings of the adjacent layers. The stack of layers is secured to form the segmented core.

Lawrence, Robert Anthony (Kokomo, IN); Stabel, Gerald R (Swartz Creek, MI)

2003-06-17

466

Wind Tubes  

NSDL National Science Digital Library

In this activity, learners create and experiment with wind tubes. These tubes are a playful and inventive way to explore the effect that moving air has on objects. Construction uses everyday materials such as a fan and embroidery hoops. Itâs fun to make things fly out of or float in the tubes, and to adjust the tubes to change the way the objects fly. The activity requires a significant amount of time and resources to build and may require adult help in construction. Experimentation with the wind tubes is engaging for a wide age range of learners.

Exploratorium

2012-12-14

467

Machine tool locator  

DOEpatents

Machine tools can be accurately measured and positioned on manufacturing machines within very small tolerances by use of an autocollimator on a 3-axis mount on a manufacturing machine and positioned so as to focus on a reference tooling ball or a machine tool, a digital camera connected to the viewing end of the autocollimator, and a marker and measure generator for receiving digital images from the camera, then displaying or measuring distances between the projection reticle and the reference reticle on the monitoring screen, and relating the distances to the actual position of the autocollimator relative to the reference tooling ball. The images and measurements are used to set the position of the machine tool and to measure the size and shape of the machine tool tip, and examine cutting edge wear. patent

Hanlon, John A. (Los Alamos, NM); Gill, Timothy J. (Stanley, NM)

2001-01-01

468

Fault Tolerant State Machines  

NASA Technical Reports Server (NTRS)

State machines are commonly used to control sequential logic in FPGAs and ASKS. An errant state machine can cause considerable damage to the device it is controlling. For example in space applications, the FPGA might be controlling Pyros, which when fired at the wrong time will cause a mission failure. Even a well designed state machine can be subject to random errors us a result of SEUs from the radiation environment in space. There are various ways to encode the states of a state machine, and the type of encoding makes a large difference in the susceptibility of the state machine to radiation. In this paper we compare 4 methods of state machine encoding and find which method gives the best fault tolerance, as well as determining the resources needed for each method.

Burke, Gary R.; Taft, Stephanie

2004-01-01

469

The National Wind Technology Center  

NASA Astrophysics Data System (ADS)

Wind energy research began at the Rocky Flats test site in 1976 when Rockwell International subcontracted with the Energy Research and Development Administration (ERDA). The Rocky Flats Plant was competitively selected from a number of ERDA facilities primarily because it experienced high instantaneous winds and provided a large, clear land area. By 1977, several small wind turbines were in place. During the facility's peak of operation, in 1979-1980, researchers were testing as many as 23 small wind turbines of various configurations, including commercially available machines and prototype turbines developed under subcontract to Rocky Flats. Facilities also included 8-kW, 40-kW, and 225-kW dynamometers; a variable-speed test bed; a wind/hybrid test facility; a controlled velocity test facility (in Pueblo, Colorado); a modal test facility, and a multimegawatt switchgear facility. The main laboratory building was dedicated in July 1981 and was operated by the Rocky Flats Plant until 1984, when the Solar Energy Research Institute (SERI) and Rocky Flats wind energy programs were merged and transferred to SERI. SERI and now the National Renewable Energy Laboratory (NREL) continued to conduct wind turbine system component tests after 1987, when most program personnel were moved to the Denver West Office Park in Golden and site ownership was transferred back to Rocky Flats. The Combined Experiment test bed was installed and began operation in 1988, and the NREL structural test facility began operation in 1990. In 1993, the site's operation was officially transferred to the DOE Golden Field Office that oversees NREL. This move was in anticipation of NREL's renovation and reoccupation of the facility in 1994.

Thresher, R. W.; Hock, S. M.; Loose, R. R.; Cadogon, J. B.

1994-07-01

470

Development and Validation of a Comprehensive Synchronous Machine Model for a Real-Time Environment  

Microsoft Academic Search

A comprehensive model of a salient-pole synchronous machine is developed for a real-time environment. By obtaining the effective specific permeance of the machine from simple experimental measurements and the exact geometry of the rotor pole arc, a model is developed that includes the exact distribution of windings and operating-point-dependent saturation. This model offers a superior simulated response of the machine

A. B. Dehkordi; Prabhakar Neti; A. M. Gole; T. L. Maguire

2010-01-01

471

Geometric Control of Vimentin Intermediate Filaments  

PubMed Central

Significant efforts have addressed the role of vimentin intermediate filaments (VIF) in cell motility, shape, adhesion and their connections to microfilaments (MF) and microtubules (MT). The present work uses micropatterned substrates to control the shapes of mouse fibroblasts and demonstrates that the cytoskeletal elements are dependent on each other and that unlike MF, VIF are globally controlled. For example, both square and circle-shaped cells have a similar VIF distribution while MF distributions in these two shapes are quite different and depend on the curvature of the shape. Furthermore, in asymmetric and polarized shaped cells VIF avoid the sharp edges where MF are highly localized. Experiments with vimentin-null mouse embryonic fibroblasts (MEFs) adherent to polarized (teardrop) and un-polarized (dumbbell) patterns show that the absence of VIF alters microtubule organization and perturbs cell polarity. The results of this study also demonstrate the utility of patterned substrates for quantitative studies of cytoskeleton organization in adherent cells. PMID:24268665

Goldman, Robert D.; Mrksich, Milan

2013-01-01

472

Filament wound data base development, revision 1  

NASA Technical Reports Server (NTRS)

The objective was to update the present Space Shuttle Solid Rocket Booster (SRB) baseline reentry aerodynamic data base and to develop a new reentry data base for the filament wound case SRB along with individual protuberance increments. Lockheed's procedures for performing these tasks are discussed. Free fall of the SRBs after separation from the Space Shuttle Launch Vehicle is completely uncontrolled. However, the SRBs must decelerate to a velocity and attitude that is suitable for parachute deployment. To determine the SRB reentry trajectory parameters, including the rate of deceleration and attitude history during free-fall, engineers at Marshall Space Flight Center are using a six-degree-of-freedom computer program to predict dynamic behavior. Static stability aerodynamic coefficients are part of the information required for input into this computer program. Lockheed analyzed the existing reentry aerodynamic data tape (Data Tape 5) for the current steel case SRB. This analysis resulted in the development of Data Tape 7.

Sharp, R. Scott; Braddock, William F.

1985-01-01

473

Introducing intermediate filaments: from discovery to disease  

PubMed Central

It took more than 100 years before it was established that the proteins that form intermediate filaments (IFs) comprise a unified protein family, the members of which are ubiquitous in virtually all differentiated cells and present both in the cytoplasm and in the nucleus. However, during the past 2 decades, knowledge regarding the functions of these structures has been expanding rapidly. Many disease-related roles of IFs have been revealed. In some cases, the molecular mechanisms underlying these diseases reflect disturbances in the functions traditionally assigned to IFs, i.e., maintenance of structural and mechanical integrity of cells and tissues. However, many disease conditions seem to link to the nonmechanical functions of IFs, many of which have been defined only in the past few years. PMID:19587451

Eriksson, John E.; Dechat, Thomas; Grin, Boris; Helfand, Brian; Mendez, Melissa; Pallari, Hanna-Mari; Goldman, Robert D.

2009-01-01

474

Cryogenic glass-filament-wound tank evaluation  

NASA Technical Reports Server (NTRS)

High-pressure glass-filament-wound fluid storage vessels with thin aluminum liners were designed, fabricated, and tested at ambient and cryogenic temperatures which demonstrated the feasibility of producing such vessels as well as high performance and light weight. Significant developments and advancements were made in solving problems associated with the thin metal liners in the tanks, including liner bonding to the overwrap and high strain magnification at the vessel polar bosses. The vessels had very high burst strengths, and failed in cyclic fatigue tests by local liner fracture and leakage without structural failure of the composite tank wall. The weight of the tanks was only 40 to 55% of comparable 2219-T87 aluminum and Inconel 718 tanks.

Morris, E. E.; Landes, R. E.

1971-01-01

475

What Can Turing Machines Do? How powerful are Turing machines?  

E-print Network

1 What Can Turing Machines Do? How powerful are Turing machines? Turing machines can accept any regular or context- free language. Turing machines can perform basic arithmetic computations. Sequencing can be implemented on Turing ma- chines. Subroutine calls can be implemented on Turing machines

Bylander, Tom

476

Quantum Learning Machine  

E-print Network

We propose a novel notion of a quantum learning machine for automatically controlling quantum coherence and for developing quantum algorithms. A quantum learning machine can be trained to learn a certain task with no a priori knowledge on its algorithm. As an example, it is demonstrated that the quantum learning machine learns Deutsch's task and finds itself a quantum algorithm, that is different from but equivalent to the original one.

Jeongho Bang; James Lim; M. S. Kim; Jinhyoung Lee

2008-03-31

477

Machining: An Introduction  

NSDL National Science Digital Library

Basic machining processes are introduced on this site that is devoted to engineering fundamentals. Descriptions and illustrations of drilling, turning, grinding, and other common processes are provided for people with little to no prior machining knowledge. A waterjet is a non-traditional machining technology that uses high pressure streams of water with abrasive additives rather than solid cutting instruments to slice through metal and other materials.

2008-04-23

478

Edheads: Simple Machines  

NSDL National Science Digital Library

This interactive Flash activity invites kids to learn about simple and compound machines by investigating common household objects found in the kitchen and tool shed. The animated activities help them understand how the machines work and how to differentiate the various types of simple machine. Additionally the site provides a glossary of important terms, lesson plans and a teacher's guide. This page is part of a larger collection of game-like animations developed to teach children about science.

2007-08-16

479

RADIATION SPECTRAL SYNTHESIS OF RELATIVISTIC FILAMENTATION  

SciTech Connect

Radiation from many astrophysical sources, e.g., gamma-ray bursts and active galactic nuclei, is believed to arise from relativistically shocked collisionless plasmas. Such sources often exhibit highly transient spectra evolving rapidly compared with source lifetimes. Radiation emitted from these sources is typically associated with nonlinear plasma physics, complex field topologies, and non-thermal particle distributions. In such circumstances, a standard synchrotron paradigm may fail to produce accurate conclusions regarding the underlying physics. Simulating spectral emission and spectral evolution numerically in various relativistic shock scenarios is then the only viable method to determine the detailed physical origin of the emitted spectra. In this Letter, we present synthetic radiation spectra representing the early stage development of the filamentation (streaming) instability of an initially unmagnetized plasma, which is relevant for both collisionless shock formation and reconnection dynamics in relativistic astrophysical outflows as well as for laboratory astrophysics experiments. Results were obtained using a highly efficient in situ diagnostics method, based on detailed particle-in-cell modeling of collisionless plasmas. The synthetic spectra obtained here are compared with those predicted by a semi-analytical model for jitter radiation from the filamentation instability, the latter including self-consistent generated field topologies and particle distributions obtained from the simulations reported upon here. Spectra exhibit dependence on the presence-or the absence-of an inert plasma constituent, when comparing baryonic plasmas (i.e., containing protons) with pair plasmas. The results also illustrate that considerable care should be taken when using lower-dimensional models to obtain information about the astrophysical phenomena generating observed spectra.

Frederiksen, Jacob Trier; Haugboelle, Troels; Medvedev, Mikhail V.; Nordlund, Ake, E-mail: trier@nbi.d [Niels Bohr International Academy, Blegdamsvej 17, DK-2199 Koebenhavn (Denmark)

2010-10-10

480

Development of a process for producing ribbon shaped filaments. [production of silicon carbide filaments  

NASA Technical Reports Server (NTRS)

Silicon carbide (SiC) ribbon filaments were produced on a carbon ribbon substrate, about 1500 microns (60 mils) wide and 100 microns (4 mils) thick in lengths up to 2 meters (6 ft), and with tensile strengths up to 142 KN/cm sq (206 Ksi). During the course of the study, ribbon filaments of boron were also produced on the carbon ribbon substrate; the boron ribbon produced was extremely fragile. The tensile strength of the SiC ribbon was limited by large growths or flaws caused by anomalies at the substrate surface; these anomalies were either foreign dirt or substrate imperfections or both. Related work carried out on round 100 micron (4 mils) diameter SiC filaments on a 33 micron (1.3 mil) diameter, very smooth carbon monofilament substrate has shown that tensile strengths as high as 551 KN/cm sq (800 Ksi) are obtainable with the SiC-carbon round substrate combination, and indicates that if the ribbon substrate surface and ribbon deposition process can be improved similar strengths can be realizable. Cost analysis shows that 100 micron x 5-10 micron SiC ribbon can be very low cost reinforcement material.

Debolt, H. E.; Krukonis, V. J.

1973-01-01